xref: /linux/fs/ext4/inode.c (revision 55223394d56bab42ebac71ba52e0fd8bfdc6fc07)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  linux/fs/ext4/inode.c
4  *
5  * Copyright (C) 1992, 1993, 1994, 1995
6  * Remy Card (card@masi.ibp.fr)
7  * Laboratoire MASI - Institut Blaise Pascal
8  * Universite Pierre et Marie Curie (Paris VI)
9  *
10  *  from
11  *
12  *  linux/fs/minix/inode.c
13  *
14  *  Copyright (C) 1991, 1992  Linus Torvalds
15  *
16  *  64-bit file support on 64-bit platforms by Jakub Jelinek
17  *	(jj@sunsite.ms.mff.cuni.cz)
18  *
19  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
20  */
21 
22 #include <linux/fs.h>
23 #include <linux/time.h>
24 #include <linux/highuid.h>
25 #include <linux/pagemap.h>
26 #include <linux/dax.h>
27 #include <linux/quotaops.h>
28 #include <linux/string.h>
29 #include <linux/buffer_head.h>
30 #include <linux/writeback.h>
31 #include <linux/pagevec.h>
32 #include <linux/mpage.h>
33 #include <linux/namei.h>
34 #include <linux/uio.h>
35 #include <linux/bio.h>
36 #include <linux/workqueue.h>
37 #include <linux/kernel.h>
38 #include <linux/printk.h>
39 #include <linux/slab.h>
40 #include <linux/bitops.h>
41 #include <linux/iomap.h>
42 #include <linux/iversion.h>
43 
44 #include "ext4_jbd2.h"
45 #include "xattr.h"
46 #include "acl.h"
47 #include "truncate.h"
48 
49 #include <trace/events/ext4.h>
50 
51 #define MPAGE_DA_EXTENT_TAIL 0x01
52 
53 static __u32 ext4_inode_csum(struct inode *inode, struct ext4_inode *raw,
54 			      struct ext4_inode_info *ei)
55 {
56 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
57 	__u32 csum;
58 	__u16 dummy_csum = 0;
59 	int offset = offsetof(struct ext4_inode, i_checksum_lo);
60 	unsigned int csum_size = sizeof(dummy_csum);
61 
62 	csum = ext4_chksum(sbi, ei->i_csum_seed, (__u8 *)raw, offset);
63 	csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum, csum_size);
64 	offset += csum_size;
65 	csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
66 			   EXT4_GOOD_OLD_INODE_SIZE - offset);
67 
68 	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
69 		offset = offsetof(struct ext4_inode, i_checksum_hi);
70 		csum = ext4_chksum(sbi, csum, (__u8 *)raw +
71 				   EXT4_GOOD_OLD_INODE_SIZE,
72 				   offset - EXT4_GOOD_OLD_INODE_SIZE);
73 		if (EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi)) {
74 			csum = ext4_chksum(sbi, csum, (__u8 *)&dummy_csum,
75 					   csum_size);
76 			offset += csum_size;
77 		}
78 		csum = ext4_chksum(sbi, csum, (__u8 *)raw + offset,
79 				   EXT4_INODE_SIZE(inode->i_sb) - offset);
80 	}
81 
82 	return csum;
83 }
84 
85 static int ext4_inode_csum_verify(struct inode *inode, struct ext4_inode *raw,
86 				  struct ext4_inode_info *ei)
87 {
88 	__u32 provided, calculated;
89 
90 	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
91 	    cpu_to_le32(EXT4_OS_LINUX) ||
92 	    !ext4_has_metadata_csum(inode->i_sb))
93 		return 1;
94 
95 	provided = le16_to_cpu(raw->i_checksum_lo);
96 	calculated = ext4_inode_csum(inode, raw, ei);
97 	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
98 	    EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
99 		provided |= ((__u32)le16_to_cpu(raw->i_checksum_hi)) << 16;
100 	else
101 		calculated &= 0xFFFF;
102 
103 	return provided == calculated;
104 }
105 
106 static void ext4_inode_csum_set(struct inode *inode, struct ext4_inode *raw,
107 				struct ext4_inode_info *ei)
108 {
109 	__u32 csum;
110 
111 	if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
112 	    cpu_to_le32(EXT4_OS_LINUX) ||
113 	    !ext4_has_metadata_csum(inode->i_sb))
114 		return;
115 
116 	csum = ext4_inode_csum(inode, raw, ei);
117 	raw->i_checksum_lo = cpu_to_le16(csum & 0xFFFF);
118 	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
119 	    EXT4_FITS_IN_INODE(raw, ei, i_checksum_hi))
120 		raw->i_checksum_hi = cpu_to_le16(csum >> 16);
121 }
122 
123 static inline int ext4_begin_ordered_truncate(struct inode *inode,
124 					      loff_t new_size)
125 {
126 	trace_ext4_begin_ordered_truncate(inode, new_size);
127 	/*
128 	 * If jinode is zero, then we never opened the file for
129 	 * writing, so there's no need to call
130 	 * jbd2_journal_begin_ordered_truncate() since there's no
131 	 * outstanding writes we need to flush.
132 	 */
133 	if (!EXT4_I(inode)->jinode)
134 		return 0;
135 	return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
136 						   EXT4_I(inode)->jinode,
137 						   new_size);
138 }
139 
140 static void ext4_invalidatepage(struct page *page, unsigned int offset,
141 				unsigned int length);
142 static int __ext4_journalled_writepage(struct page *page, unsigned int len);
143 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh);
144 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
145 				  int pextents);
146 
147 /*
148  * Test whether an inode is a fast symlink.
149  * A fast symlink has its symlink data stored in ext4_inode_info->i_data.
150  */
151 int ext4_inode_is_fast_symlink(struct inode *inode)
152 {
153 	if (!(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL)) {
154 		int ea_blocks = EXT4_I(inode)->i_file_acl ?
155 				EXT4_CLUSTER_SIZE(inode->i_sb) >> 9 : 0;
156 
157 		if (ext4_has_inline_data(inode))
158 			return 0;
159 
160 		return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
161 	}
162 	return S_ISLNK(inode->i_mode) && inode->i_size &&
163 	       (inode->i_size < EXT4_N_BLOCKS * 4);
164 }
165 
166 /*
167  * Restart the transaction associated with *handle.  This does a commit,
168  * so before we call here everything must be consistently dirtied against
169  * this transaction.
170  */
171 int ext4_truncate_restart_trans(handle_t *handle, struct inode *inode,
172 				 int nblocks)
173 {
174 	int ret;
175 
176 	/*
177 	 * Drop i_data_sem to avoid deadlock with ext4_map_blocks.  At this
178 	 * moment, get_block can be called only for blocks inside i_size since
179 	 * page cache has been already dropped and writes are blocked by
180 	 * i_mutex. So we can safely drop the i_data_sem here.
181 	 */
182 	BUG_ON(EXT4_JOURNAL(inode) == NULL);
183 	jbd_debug(2, "restarting handle %p\n", handle);
184 	up_write(&EXT4_I(inode)->i_data_sem);
185 	ret = ext4_journal_restart(handle, nblocks);
186 	down_write(&EXT4_I(inode)->i_data_sem);
187 	ext4_discard_preallocations(inode);
188 
189 	return ret;
190 }
191 
192 /*
193  * Called at the last iput() if i_nlink is zero.
194  */
195 void ext4_evict_inode(struct inode *inode)
196 {
197 	handle_t *handle;
198 	int err;
199 	int extra_credits = 3;
200 	struct ext4_xattr_inode_array *ea_inode_array = NULL;
201 
202 	trace_ext4_evict_inode(inode);
203 
204 	if (inode->i_nlink) {
205 		/*
206 		 * When journalling data dirty buffers are tracked only in the
207 		 * journal. So although mm thinks everything is clean and
208 		 * ready for reaping the inode might still have some pages to
209 		 * write in the running transaction or waiting to be
210 		 * checkpointed. Thus calling jbd2_journal_invalidatepage()
211 		 * (via truncate_inode_pages()) to discard these buffers can
212 		 * cause data loss. Also even if we did not discard these
213 		 * buffers, we would have no way to find them after the inode
214 		 * is reaped and thus user could see stale data if he tries to
215 		 * read them before the transaction is checkpointed. So be
216 		 * careful and force everything to disk here... We use
217 		 * ei->i_datasync_tid to store the newest transaction
218 		 * containing inode's data.
219 		 *
220 		 * Note that directories do not have this problem because they
221 		 * don't use page cache.
222 		 */
223 		if (inode->i_ino != EXT4_JOURNAL_INO &&
224 		    ext4_should_journal_data(inode) &&
225 		    (S_ISLNK(inode->i_mode) || S_ISREG(inode->i_mode)) &&
226 		    inode->i_data.nrpages) {
227 			journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
228 			tid_t commit_tid = EXT4_I(inode)->i_datasync_tid;
229 
230 			jbd2_complete_transaction(journal, commit_tid);
231 			filemap_write_and_wait(&inode->i_data);
232 		}
233 		truncate_inode_pages_final(&inode->i_data);
234 
235 		goto no_delete;
236 	}
237 
238 	if (is_bad_inode(inode))
239 		goto no_delete;
240 	dquot_initialize(inode);
241 
242 	if (ext4_should_order_data(inode))
243 		ext4_begin_ordered_truncate(inode, 0);
244 	truncate_inode_pages_final(&inode->i_data);
245 
246 	/*
247 	 * Protect us against freezing - iput() caller didn't have to have any
248 	 * protection against it
249 	 */
250 	sb_start_intwrite(inode->i_sb);
251 
252 	if (!IS_NOQUOTA(inode))
253 		extra_credits += EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb);
254 
255 	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE,
256 				 ext4_blocks_for_truncate(inode)+extra_credits);
257 	if (IS_ERR(handle)) {
258 		ext4_std_error(inode->i_sb, PTR_ERR(handle));
259 		/*
260 		 * If we're going to skip the normal cleanup, we still need to
261 		 * make sure that the in-core orphan linked list is properly
262 		 * cleaned up.
263 		 */
264 		ext4_orphan_del(NULL, inode);
265 		sb_end_intwrite(inode->i_sb);
266 		goto no_delete;
267 	}
268 
269 	if (IS_SYNC(inode))
270 		ext4_handle_sync(handle);
271 
272 	/*
273 	 * Set inode->i_size to 0 before calling ext4_truncate(). We need
274 	 * special handling of symlinks here because i_size is used to
275 	 * determine whether ext4_inode_info->i_data contains symlink data or
276 	 * block mappings. Setting i_size to 0 will remove its fast symlink
277 	 * status. Erase i_data so that it becomes a valid empty block map.
278 	 */
279 	if (ext4_inode_is_fast_symlink(inode))
280 		memset(EXT4_I(inode)->i_data, 0, sizeof(EXT4_I(inode)->i_data));
281 	inode->i_size = 0;
282 	err = ext4_mark_inode_dirty(handle, inode);
283 	if (err) {
284 		ext4_warning(inode->i_sb,
285 			     "couldn't mark inode dirty (err %d)", err);
286 		goto stop_handle;
287 	}
288 	if (inode->i_blocks) {
289 		err = ext4_truncate(inode);
290 		if (err) {
291 			ext4_error(inode->i_sb,
292 				   "couldn't truncate inode %lu (err %d)",
293 				   inode->i_ino, err);
294 			goto stop_handle;
295 		}
296 	}
297 
298 	/* Remove xattr references. */
299 	err = ext4_xattr_delete_inode(handle, inode, &ea_inode_array,
300 				      extra_credits);
301 	if (err) {
302 		ext4_warning(inode->i_sb, "xattr delete (err %d)", err);
303 stop_handle:
304 		ext4_journal_stop(handle);
305 		ext4_orphan_del(NULL, inode);
306 		sb_end_intwrite(inode->i_sb);
307 		ext4_xattr_inode_array_free(ea_inode_array);
308 		goto no_delete;
309 	}
310 
311 	/*
312 	 * Kill off the orphan record which ext4_truncate created.
313 	 * AKPM: I think this can be inside the above `if'.
314 	 * Note that ext4_orphan_del() has to be able to cope with the
315 	 * deletion of a non-existent orphan - this is because we don't
316 	 * know if ext4_truncate() actually created an orphan record.
317 	 * (Well, we could do this if we need to, but heck - it works)
318 	 */
319 	ext4_orphan_del(handle, inode);
320 	EXT4_I(inode)->i_dtime	= (__u32)ktime_get_real_seconds();
321 
322 	/*
323 	 * One subtle ordering requirement: if anything has gone wrong
324 	 * (transaction abort, IO errors, whatever), then we can still
325 	 * do these next steps (the fs will already have been marked as
326 	 * having errors), but we can't free the inode if the mark_dirty
327 	 * fails.
328 	 */
329 	if (ext4_mark_inode_dirty(handle, inode))
330 		/* If that failed, just do the required in-core inode clear. */
331 		ext4_clear_inode(inode);
332 	else
333 		ext4_free_inode(handle, inode);
334 	ext4_journal_stop(handle);
335 	sb_end_intwrite(inode->i_sb);
336 	ext4_xattr_inode_array_free(ea_inode_array);
337 	return;
338 no_delete:
339 	ext4_clear_inode(inode);	/* We must guarantee clearing of inode... */
340 }
341 
342 #ifdef CONFIG_QUOTA
343 qsize_t *ext4_get_reserved_space(struct inode *inode)
344 {
345 	return &EXT4_I(inode)->i_reserved_quota;
346 }
347 #endif
348 
349 /*
350  * Called with i_data_sem down, which is important since we can call
351  * ext4_discard_preallocations() from here.
352  */
353 void ext4_da_update_reserve_space(struct inode *inode,
354 					int used, int quota_claim)
355 {
356 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
357 	struct ext4_inode_info *ei = EXT4_I(inode);
358 
359 	spin_lock(&ei->i_block_reservation_lock);
360 	trace_ext4_da_update_reserve_space(inode, used, quota_claim);
361 	if (unlikely(used > ei->i_reserved_data_blocks)) {
362 		ext4_warning(inode->i_sb, "%s: ino %lu, used %d "
363 			 "with only %d reserved data blocks",
364 			 __func__, inode->i_ino, used,
365 			 ei->i_reserved_data_blocks);
366 		WARN_ON(1);
367 		used = ei->i_reserved_data_blocks;
368 	}
369 
370 	/* Update per-inode reservations */
371 	ei->i_reserved_data_blocks -= used;
372 	percpu_counter_sub(&sbi->s_dirtyclusters_counter, used);
373 
374 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
375 
376 	/* Update quota subsystem for data blocks */
377 	if (quota_claim)
378 		dquot_claim_block(inode, EXT4_C2B(sbi, used));
379 	else {
380 		/*
381 		 * We did fallocate with an offset that is already delayed
382 		 * allocated. So on delayed allocated writeback we should
383 		 * not re-claim the quota for fallocated blocks.
384 		 */
385 		dquot_release_reservation_block(inode, EXT4_C2B(sbi, used));
386 	}
387 
388 	/*
389 	 * If we have done all the pending block allocations and if
390 	 * there aren't any writers on the inode, we can discard the
391 	 * inode's preallocations.
392 	 */
393 	if ((ei->i_reserved_data_blocks == 0) &&
394 	    !inode_is_open_for_write(inode))
395 		ext4_discard_preallocations(inode);
396 }
397 
398 static int __check_block_validity(struct inode *inode, const char *func,
399 				unsigned int line,
400 				struct ext4_map_blocks *map)
401 {
402 	if (!ext4_data_block_valid(EXT4_SB(inode->i_sb), map->m_pblk,
403 				   map->m_len)) {
404 		ext4_error_inode(inode, func, line, map->m_pblk,
405 				 "lblock %lu mapped to illegal pblock %llu "
406 				 "(length %d)", (unsigned long) map->m_lblk,
407 				 map->m_pblk, map->m_len);
408 		return -EFSCORRUPTED;
409 	}
410 	return 0;
411 }
412 
413 int ext4_issue_zeroout(struct inode *inode, ext4_lblk_t lblk, ext4_fsblk_t pblk,
414 		       ext4_lblk_t len)
415 {
416 	int ret;
417 
418 	if (IS_ENCRYPTED(inode))
419 		return fscrypt_zeroout_range(inode, lblk, pblk, len);
420 
421 	ret = sb_issue_zeroout(inode->i_sb, pblk, len, GFP_NOFS);
422 	if (ret > 0)
423 		ret = 0;
424 
425 	return ret;
426 }
427 
428 #define check_block_validity(inode, map)	\
429 	__check_block_validity((inode), __func__, __LINE__, (map))
430 
431 #ifdef ES_AGGRESSIVE_TEST
432 static void ext4_map_blocks_es_recheck(handle_t *handle,
433 				       struct inode *inode,
434 				       struct ext4_map_blocks *es_map,
435 				       struct ext4_map_blocks *map,
436 				       int flags)
437 {
438 	int retval;
439 
440 	map->m_flags = 0;
441 	/*
442 	 * There is a race window that the result is not the same.
443 	 * e.g. xfstests #223 when dioread_nolock enables.  The reason
444 	 * is that we lookup a block mapping in extent status tree with
445 	 * out taking i_data_sem.  So at the time the unwritten extent
446 	 * could be converted.
447 	 */
448 	down_read(&EXT4_I(inode)->i_data_sem);
449 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
450 		retval = ext4_ext_map_blocks(handle, inode, map, flags &
451 					     EXT4_GET_BLOCKS_KEEP_SIZE);
452 	} else {
453 		retval = ext4_ind_map_blocks(handle, inode, map, flags &
454 					     EXT4_GET_BLOCKS_KEEP_SIZE);
455 	}
456 	up_read((&EXT4_I(inode)->i_data_sem));
457 
458 	/*
459 	 * We don't check m_len because extent will be collpased in status
460 	 * tree.  So the m_len might not equal.
461 	 */
462 	if (es_map->m_lblk != map->m_lblk ||
463 	    es_map->m_flags != map->m_flags ||
464 	    es_map->m_pblk != map->m_pblk) {
465 		printk("ES cache assertion failed for inode: %lu "
466 		       "es_cached ex [%d/%d/%llu/%x] != "
467 		       "found ex [%d/%d/%llu/%x] retval %d flags %x\n",
468 		       inode->i_ino, es_map->m_lblk, es_map->m_len,
469 		       es_map->m_pblk, es_map->m_flags, map->m_lblk,
470 		       map->m_len, map->m_pblk, map->m_flags,
471 		       retval, flags);
472 	}
473 }
474 #endif /* ES_AGGRESSIVE_TEST */
475 
476 /*
477  * The ext4_map_blocks() function tries to look up the requested blocks,
478  * and returns if the blocks are already mapped.
479  *
480  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
481  * and store the allocated blocks in the result buffer head and mark it
482  * mapped.
483  *
484  * If file type is extents based, it will call ext4_ext_map_blocks(),
485  * Otherwise, call with ext4_ind_map_blocks() to handle indirect mapping
486  * based files
487  *
488  * On success, it returns the number of blocks being mapped or allocated.  if
489  * create==0 and the blocks are pre-allocated and unwritten, the resulting @map
490  * is marked as unwritten. If the create == 1, it will mark @map as mapped.
491  *
492  * It returns 0 if plain look up failed (blocks have not been allocated), in
493  * that case, @map is returned as unmapped but we still do fill map->m_len to
494  * indicate the length of a hole starting at map->m_lblk.
495  *
496  * It returns the error in case of allocation failure.
497  */
498 int ext4_map_blocks(handle_t *handle, struct inode *inode,
499 		    struct ext4_map_blocks *map, int flags)
500 {
501 	struct extent_status es;
502 	int retval;
503 	int ret = 0;
504 #ifdef ES_AGGRESSIVE_TEST
505 	struct ext4_map_blocks orig_map;
506 
507 	memcpy(&orig_map, map, sizeof(*map));
508 #endif
509 
510 	map->m_flags = 0;
511 	ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
512 		  "logical block %lu\n", inode->i_ino, flags, map->m_len,
513 		  (unsigned long) map->m_lblk);
514 
515 	/*
516 	 * ext4_map_blocks returns an int, and m_len is an unsigned int
517 	 */
518 	if (unlikely(map->m_len > INT_MAX))
519 		map->m_len = INT_MAX;
520 
521 	/* We can handle the block number less than EXT_MAX_BLOCKS */
522 	if (unlikely(map->m_lblk >= EXT_MAX_BLOCKS))
523 		return -EFSCORRUPTED;
524 
525 	/* Lookup extent status tree firstly */
526 	if (ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
527 		if (ext4_es_is_written(&es) || ext4_es_is_unwritten(&es)) {
528 			map->m_pblk = ext4_es_pblock(&es) +
529 					map->m_lblk - es.es_lblk;
530 			map->m_flags |= ext4_es_is_written(&es) ?
531 					EXT4_MAP_MAPPED : EXT4_MAP_UNWRITTEN;
532 			retval = es.es_len - (map->m_lblk - es.es_lblk);
533 			if (retval > map->m_len)
534 				retval = map->m_len;
535 			map->m_len = retval;
536 		} else if (ext4_es_is_delayed(&es) || ext4_es_is_hole(&es)) {
537 			map->m_pblk = 0;
538 			retval = es.es_len - (map->m_lblk - es.es_lblk);
539 			if (retval > map->m_len)
540 				retval = map->m_len;
541 			map->m_len = retval;
542 			retval = 0;
543 		} else {
544 			BUG_ON(1);
545 		}
546 #ifdef ES_AGGRESSIVE_TEST
547 		ext4_map_blocks_es_recheck(handle, inode, map,
548 					   &orig_map, flags);
549 #endif
550 		goto found;
551 	}
552 
553 	/*
554 	 * Try to see if we can get the block without requesting a new
555 	 * file system block.
556 	 */
557 	down_read(&EXT4_I(inode)->i_data_sem);
558 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
559 		retval = ext4_ext_map_blocks(handle, inode, map, flags &
560 					     EXT4_GET_BLOCKS_KEEP_SIZE);
561 	} else {
562 		retval = ext4_ind_map_blocks(handle, inode, map, flags &
563 					     EXT4_GET_BLOCKS_KEEP_SIZE);
564 	}
565 	if (retval > 0) {
566 		unsigned int status;
567 
568 		if (unlikely(retval != map->m_len)) {
569 			ext4_warning(inode->i_sb,
570 				     "ES len assertion failed for inode "
571 				     "%lu: retval %d != map->m_len %d",
572 				     inode->i_ino, retval, map->m_len);
573 			WARN_ON(1);
574 		}
575 
576 		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
577 				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
578 		if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
579 		    !(status & EXTENT_STATUS_WRITTEN) &&
580 		    ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
581 				       map->m_lblk + map->m_len - 1))
582 			status |= EXTENT_STATUS_DELAYED;
583 		ret = ext4_es_insert_extent(inode, map->m_lblk,
584 					    map->m_len, map->m_pblk, status);
585 		if (ret < 0)
586 			retval = ret;
587 	}
588 	up_read((&EXT4_I(inode)->i_data_sem));
589 
590 found:
591 	if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
592 		ret = check_block_validity(inode, map);
593 		if (ret != 0)
594 			return ret;
595 	}
596 
597 	/* If it is only a block(s) look up */
598 	if ((flags & EXT4_GET_BLOCKS_CREATE) == 0)
599 		return retval;
600 
601 	/*
602 	 * Returns if the blocks have already allocated
603 	 *
604 	 * Note that if blocks have been preallocated
605 	 * ext4_ext_get_block() returns the create = 0
606 	 * with buffer head unmapped.
607 	 */
608 	if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED)
609 		/*
610 		 * If we need to convert extent to unwritten
611 		 * we continue and do the actual work in
612 		 * ext4_ext_map_blocks()
613 		 */
614 		if (!(flags & EXT4_GET_BLOCKS_CONVERT_UNWRITTEN))
615 			return retval;
616 
617 	/*
618 	 * Here we clear m_flags because after allocating an new extent,
619 	 * it will be set again.
620 	 */
621 	map->m_flags &= ~EXT4_MAP_FLAGS;
622 
623 	/*
624 	 * New blocks allocate and/or writing to unwritten extent
625 	 * will possibly result in updating i_data, so we take
626 	 * the write lock of i_data_sem, and call get_block()
627 	 * with create == 1 flag.
628 	 */
629 	down_write(&EXT4_I(inode)->i_data_sem);
630 
631 	/*
632 	 * We need to check for EXT4 here because migrate
633 	 * could have changed the inode type in between
634 	 */
635 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
636 		retval = ext4_ext_map_blocks(handle, inode, map, flags);
637 	} else {
638 		retval = ext4_ind_map_blocks(handle, inode, map, flags);
639 
640 		if (retval > 0 && map->m_flags & EXT4_MAP_NEW) {
641 			/*
642 			 * We allocated new blocks which will result in
643 			 * i_data's format changing.  Force the migrate
644 			 * to fail by clearing migrate flags
645 			 */
646 			ext4_clear_inode_state(inode, EXT4_STATE_EXT_MIGRATE);
647 		}
648 
649 		/*
650 		 * Update reserved blocks/metadata blocks after successful
651 		 * block allocation which had been deferred till now. We don't
652 		 * support fallocate for non extent files. So we can update
653 		 * reserve space here.
654 		 */
655 		if ((retval > 0) &&
656 			(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE))
657 			ext4_da_update_reserve_space(inode, retval, 1);
658 	}
659 
660 	if (retval > 0) {
661 		unsigned int status;
662 
663 		if (unlikely(retval != map->m_len)) {
664 			ext4_warning(inode->i_sb,
665 				     "ES len assertion failed for inode "
666 				     "%lu: retval %d != map->m_len %d",
667 				     inode->i_ino, retval, map->m_len);
668 			WARN_ON(1);
669 		}
670 
671 		/*
672 		 * We have to zeroout blocks before inserting them into extent
673 		 * status tree. Otherwise someone could look them up there and
674 		 * use them before they are really zeroed. We also have to
675 		 * unmap metadata before zeroing as otherwise writeback can
676 		 * overwrite zeros with stale data from block device.
677 		 */
678 		if (flags & EXT4_GET_BLOCKS_ZERO &&
679 		    map->m_flags & EXT4_MAP_MAPPED &&
680 		    map->m_flags & EXT4_MAP_NEW) {
681 			ret = ext4_issue_zeroout(inode, map->m_lblk,
682 						 map->m_pblk, map->m_len);
683 			if (ret) {
684 				retval = ret;
685 				goto out_sem;
686 			}
687 		}
688 
689 		/*
690 		 * If the extent has been zeroed out, we don't need to update
691 		 * extent status tree.
692 		 */
693 		if ((flags & EXT4_GET_BLOCKS_PRE_IO) &&
694 		    ext4_es_lookup_extent(inode, map->m_lblk, &es)) {
695 			if (ext4_es_is_written(&es))
696 				goto out_sem;
697 		}
698 		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
699 				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
700 		if (!(flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE) &&
701 		    !(status & EXTENT_STATUS_WRITTEN) &&
702 		    ext4_es_scan_range(inode, &ext4_es_is_delayed, map->m_lblk,
703 				       map->m_lblk + map->m_len - 1))
704 			status |= EXTENT_STATUS_DELAYED;
705 		ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
706 					    map->m_pblk, status);
707 		if (ret < 0) {
708 			retval = ret;
709 			goto out_sem;
710 		}
711 	}
712 
713 out_sem:
714 	up_write((&EXT4_I(inode)->i_data_sem));
715 	if (retval > 0 && map->m_flags & EXT4_MAP_MAPPED) {
716 		ret = check_block_validity(inode, map);
717 		if (ret != 0)
718 			return ret;
719 
720 		/*
721 		 * Inodes with freshly allocated blocks where contents will be
722 		 * visible after transaction commit must be on transaction's
723 		 * ordered data list.
724 		 */
725 		if (map->m_flags & EXT4_MAP_NEW &&
726 		    !(map->m_flags & EXT4_MAP_UNWRITTEN) &&
727 		    !(flags & EXT4_GET_BLOCKS_ZERO) &&
728 		    !ext4_is_quota_file(inode) &&
729 		    ext4_should_order_data(inode)) {
730 			if (flags & EXT4_GET_BLOCKS_IO_SUBMIT)
731 				ret = ext4_jbd2_inode_add_wait(handle, inode);
732 			else
733 				ret = ext4_jbd2_inode_add_write(handle, inode);
734 			if (ret)
735 				return ret;
736 		}
737 	}
738 	return retval;
739 }
740 
741 /*
742  * Update EXT4_MAP_FLAGS in bh->b_state. For buffer heads attached to pages
743  * we have to be careful as someone else may be manipulating b_state as well.
744  */
745 static void ext4_update_bh_state(struct buffer_head *bh, unsigned long flags)
746 {
747 	unsigned long old_state;
748 	unsigned long new_state;
749 
750 	flags &= EXT4_MAP_FLAGS;
751 
752 	/* Dummy buffer_head? Set non-atomically. */
753 	if (!bh->b_page) {
754 		bh->b_state = (bh->b_state & ~EXT4_MAP_FLAGS) | flags;
755 		return;
756 	}
757 	/*
758 	 * Someone else may be modifying b_state. Be careful! This is ugly but
759 	 * once we get rid of using bh as a container for mapping information
760 	 * to pass to / from get_block functions, this can go away.
761 	 */
762 	do {
763 		old_state = READ_ONCE(bh->b_state);
764 		new_state = (old_state & ~EXT4_MAP_FLAGS) | flags;
765 	} while (unlikely(
766 		 cmpxchg(&bh->b_state, old_state, new_state) != old_state));
767 }
768 
769 static int _ext4_get_block(struct inode *inode, sector_t iblock,
770 			   struct buffer_head *bh, int flags)
771 {
772 	struct ext4_map_blocks map;
773 	int ret = 0;
774 
775 	if (ext4_has_inline_data(inode))
776 		return -ERANGE;
777 
778 	map.m_lblk = iblock;
779 	map.m_len = bh->b_size >> inode->i_blkbits;
780 
781 	ret = ext4_map_blocks(ext4_journal_current_handle(), inode, &map,
782 			      flags);
783 	if (ret > 0) {
784 		map_bh(bh, inode->i_sb, map.m_pblk);
785 		ext4_update_bh_state(bh, map.m_flags);
786 		bh->b_size = inode->i_sb->s_blocksize * map.m_len;
787 		ret = 0;
788 	} else if (ret == 0) {
789 		/* hole case, need to fill in bh->b_size */
790 		bh->b_size = inode->i_sb->s_blocksize * map.m_len;
791 	}
792 	return ret;
793 }
794 
795 int ext4_get_block(struct inode *inode, sector_t iblock,
796 		   struct buffer_head *bh, int create)
797 {
798 	return _ext4_get_block(inode, iblock, bh,
799 			       create ? EXT4_GET_BLOCKS_CREATE : 0);
800 }
801 
802 /*
803  * Get block function used when preparing for buffered write if we require
804  * creating an unwritten extent if blocks haven't been allocated.  The extent
805  * will be converted to written after the IO is complete.
806  */
807 int ext4_get_block_unwritten(struct inode *inode, sector_t iblock,
808 			     struct buffer_head *bh_result, int create)
809 {
810 	ext4_debug("ext4_get_block_unwritten: inode %lu, create flag %d\n",
811 		   inode->i_ino, create);
812 	return _ext4_get_block(inode, iblock, bh_result,
813 			       EXT4_GET_BLOCKS_IO_CREATE_EXT);
814 }
815 
816 /* Maximum number of blocks we map for direct IO at once. */
817 #define DIO_MAX_BLOCKS 4096
818 
819 /*
820  * Get blocks function for the cases that need to start a transaction -
821  * generally difference cases of direct IO and DAX IO. It also handles retries
822  * in case of ENOSPC.
823  */
824 static int ext4_get_block_trans(struct inode *inode, sector_t iblock,
825 				struct buffer_head *bh_result, int flags)
826 {
827 	int dio_credits;
828 	handle_t *handle;
829 	int retries = 0;
830 	int ret;
831 
832 	/* Trim mapping request to maximum we can map at once for DIO */
833 	if (bh_result->b_size >> inode->i_blkbits > DIO_MAX_BLOCKS)
834 		bh_result->b_size = DIO_MAX_BLOCKS << inode->i_blkbits;
835 	dio_credits = ext4_chunk_trans_blocks(inode,
836 				      bh_result->b_size >> inode->i_blkbits);
837 retry:
838 	handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS, dio_credits);
839 	if (IS_ERR(handle))
840 		return PTR_ERR(handle);
841 
842 	ret = _ext4_get_block(inode, iblock, bh_result, flags);
843 	ext4_journal_stop(handle);
844 
845 	if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
846 		goto retry;
847 	return ret;
848 }
849 
850 /* Get block function for DIO reads and writes to inodes without extents */
851 int ext4_dio_get_block(struct inode *inode, sector_t iblock,
852 		       struct buffer_head *bh, int create)
853 {
854 	/* We don't expect handle for direct IO */
855 	WARN_ON_ONCE(ext4_journal_current_handle());
856 
857 	if (!create)
858 		return _ext4_get_block(inode, iblock, bh, 0);
859 	return ext4_get_block_trans(inode, iblock, bh, EXT4_GET_BLOCKS_CREATE);
860 }
861 
862 /*
863  * Get block function for AIO DIO writes when we create unwritten extent if
864  * blocks are not allocated yet. The extent will be converted to written
865  * after IO is complete.
866  */
867 static int ext4_dio_get_block_unwritten_async(struct inode *inode,
868 		sector_t iblock, struct buffer_head *bh_result,	int create)
869 {
870 	int ret;
871 
872 	/* We don't expect handle for direct IO */
873 	WARN_ON_ONCE(ext4_journal_current_handle());
874 
875 	ret = ext4_get_block_trans(inode, iblock, bh_result,
876 				   EXT4_GET_BLOCKS_IO_CREATE_EXT);
877 
878 	/*
879 	 * When doing DIO using unwritten extents, we need io_end to convert
880 	 * unwritten extents to written on IO completion. We allocate io_end
881 	 * once we spot unwritten extent and store it in b_private. Generic
882 	 * DIO code keeps b_private set and furthermore passes the value to
883 	 * our completion callback in 'private' argument.
884 	 */
885 	if (!ret && buffer_unwritten(bh_result)) {
886 		if (!bh_result->b_private) {
887 			ext4_io_end_t *io_end;
888 
889 			io_end = ext4_init_io_end(inode, GFP_KERNEL);
890 			if (!io_end)
891 				return -ENOMEM;
892 			bh_result->b_private = io_end;
893 			ext4_set_io_unwritten_flag(inode, io_end);
894 		}
895 		set_buffer_defer_completion(bh_result);
896 	}
897 
898 	return ret;
899 }
900 
901 /*
902  * Get block function for non-AIO DIO writes when we create unwritten extent if
903  * blocks are not allocated yet. The extent will be converted to written
904  * after IO is complete by ext4_direct_IO_write().
905  */
906 static int ext4_dio_get_block_unwritten_sync(struct inode *inode,
907 		sector_t iblock, struct buffer_head *bh_result,	int create)
908 {
909 	int ret;
910 
911 	/* We don't expect handle for direct IO */
912 	WARN_ON_ONCE(ext4_journal_current_handle());
913 
914 	ret = ext4_get_block_trans(inode, iblock, bh_result,
915 				   EXT4_GET_BLOCKS_IO_CREATE_EXT);
916 
917 	/*
918 	 * Mark inode as having pending DIO writes to unwritten extents.
919 	 * ext4_direct_IO_write() checks this flag and converts extents to
920 	 * written.
921 	 */
922 	if (!ret && buffer_unwritten(bh_result))
923 		ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
924 
925 	return ret;
926 }
927 
928 static int ext4_dio_get_block_overwrite(struct inode *inode, sector_t iblock,
929 		   struct buffer_head *bh_result, int create)
930 {
931 	int ret;
932 
933 	ext4_debug("ext4_dio_get_block_overwrite: inode %lu, create flag %d\n",
934 		   inode->i_ino, create);
935 	/* We don't expect handle for direct IO */
936 	WARN_ON_ONCE(ext4_journal_current_handle());
937 
938 	ret = _ext4_get_block(inode, iblock, bh_result, 0);
939 	/*
940 	 * Blocks should have been preallocated! ext4_file_write_iter() checks
941 	 * that.
942 	 */
943 	WARN_ON_ONCE(!buffer_mapped(bh_result) || buffer_unwritten(bh_result));
944 
945 	return ret;
946 }
947 
948 
949 /*
950  * `handle' can be NULL if create is zero
951  */
952 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
953 				ext4_lblk_t block, int map_flags)
954 {
955 	struct ext4_map_blocks map;
956 	struct buffer_head *bh;
957 	int create = map_flags & EXT4_GET_BLOCKS_CREATE;
958 	int err;
959 
960 	J_ASSERT(handle != NULL || create == 0);
961 
962 	map.m_lblk = block;
963 	map.m_len = 1;
964 	err = ext4_map_blocks(handle, inode, &map, map_flags);
965 
966 	if (err == 0)
967 		return create ? ERR_PTR(-ENOSPC) : NULL;
968 	if (err < 0)
969 		return ERR_PTR(err);
970 
971 	bh = sb_getblk(inode->i_sb, map.m_pblk);
972 	if (unlikely(!bh))
973 		return ERR_PTR(-ENOMEM);
974 	if (map.m_flags & EXT4_MAP_NEW) {
975 		J_ASSERT(create != 0);
976 		J_ASSERT(handle != NULL);
977 
978 		/*
979 		 * Now that we do not always journal data, we should
980 		 * keep in mind whether this should always journal the
981 		 * new buffer as metadata.  For now, regular file
982 		 * writes use ext4_get_block instead, so it's not a
983 		 * problem.
984 		 */
985 		lock_buffer(bh);
986 		BUFFER_TRACE(bh, "call get_create_access");
987 		err = ext4_journal_get_create_access(handle, bh);
988 		if (unlikely(err)) {
989 			unlock_buffer(bh);
990 			goto errout;
991 		}
992 		if (!buffer_uptodate(bh)) {
993 			memset(bh->b_data, 0, inode->i_sb->s_blocksize);
994 			set_buffer_uptodate(bh);
995 		}
996 		unlock_buffer(bh);
997 		BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
998 		err = ext4_handle_dirty_metadata(handle, inode, bh);
999 		if (unlikely(err))
1000 			goto errout;
1001 	} else
1002 		BUFFER_TRACE(bh, "not a new buffer");
1003 	return bh;
1004 errout:
1005 	brelse(bh);
1006 	return ERR_PTR(err);
1007 }
1008 
1009 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1010 			       ext4_lblk_t block, int map_flags)
1011 {
1012 	struct buffer_head *bh;
1013 
1014 	bh = ext4_getblk(handle, inode, block, map_flags);
1015 	if (IS_ERR(bh))
1016 		return bh;
1017 	if (!bh || buffer_uptodate(bh))
1018 		return bh;
1019 	ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1, &bh);
1020 	wait_on_buffer(bh);
1021 	if (buffer_uptodate(bh))
1022 		return bh;
1023 	put_bh(bh);
1024 	return ERR_PTR(-EIO);
1025 }
1026 
1027 /* Read a contiguous batch of blocks. */
1028 int ext4_bread_batch(struct inode *inode, ext4_lblk_t block, int bh_count,
1029 		     bool wait, struct buffer_head **bhs)
1030 {
1031 	int i, err;
1032 
1033 	for (i = 0; i < bh_count; i++) {
1034 		bhs[i] = ext4_getblk(NULL, inode, block + i, 0 /* map_flags */);
1035 		if (IS_ERR(bhs[i])) {
1036 			err = PTR_ERR(bhs[i]);
1037 			bh_count = i;
1038 			goto out_brelse;
1039 		}
1040 	}
1041 
1042 	for (i = 0; i < bh_count; i++)
1043 		/* Note that NULL bhs[i] is valid because of holes. */
1044 		if (bhs[i] && !buffer_uptodate(bhs[i]))
1045 			ll_rw_block(REQ_OP_READ, REQ_META | REQ_PRIO, 1,
1046 				    &bhs[i]);
1047 
1048 	if (!wait)
1049 		return 0;
1050 
1051 	for (i = 0; i < bh_count; i++)
1052 		if (bhs[i])
1053 			wait_on_buffer(bhs[i]);
1054 
1055 	for (i = 0; i < bh_count; i++) {
1056 		if (bhs[i] && !buffer_uptodate(bhs[i])) {
1057 			err = -EIO;
1058 			goto out_brelse;
1059 		}
1060 	}
1061 	return 0;
1062 
1063 out_brelse:
1064 	for (i = 0; i < bh_count; i++) {
1065 		brelse(bhs[i]);
1066 		bhs[i] = NULL;
1067 	}
1068 	return err;
1069 }
1070 
1071 int ext4_walk_page_buffers(handle_t *handle,
1072 			   struct buffer_head *head,
1073 			   unsigned from,
1074 			   unsigned to,
1075 			   int *partial,
1076 			   int (*fn)(handle_t *handle,
1077 				     struct buffer_head *bh))
1078 {
1079 	struct buffer_head *bh;
1080 	unsigned block_start, block_end;
1081 	unsigned blocksize = head->b_size;
1082 	int err, ret = 0;
1083 	struct buffer_head *next;
1084 
1085 	for (bh = head, block_start = 0;
1086 	     ret == 0 && (bh != head || !block_start);
1087 	     block_start = block_end, bh = next) {
1088 		next = bh->b_this_page;
1089 		block_end = block_start + blocksize;
1090 		if (block_end <= from || block_start >= to) {
1091 			if (partial && !buffer_uptodate(bh))
1092 				*partial = 1;
1093 			continue;
1094 		}
1095 		err = (*fn)(handle, bh);
1096 		if (!ret)
1097 			ret = err;
1098 	}
1099 	return ret;
1100 }
1101 
1102 /*
1103  * To preserve ordering, it is essential that the hole instantiation and
1104  * the data write be encapsulated in a single transaction.  We cannot
1105  * close off a transaction and start a new one between the ext4_get_block()
1106  * and the commit_write().  So doing the jbd2_journal_start at the start of
1107  * prepare_write() is the right place.
1108  *
1109  * Also, this function can nest inside ext4_writepage().  In that case, we
1110  * *know* that ext4_writepage() has generated enough buffer credits to do the
1111  * whole page.  So we won't block on the journal in that case, which is good,
1112  * because the caller may be PF_MEMALLOC.
1113  *
1114  * By accident, ext4 can be reentered when a transaction is open via
1115  * quota file writes.  If we were to commit the transaction while thus
1116  * reentered, there can be a deadlock - we would be holding a quota
1117  * lock, and the commit would never complete if another thread had a
1118  * transaction open and was blocking on the quota lock - a ranking
1119  * violation.
1120  *
1121  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1122  * will _not_ run commit under these circumstances because handle->h_ref
1123  * is elevated.  We'll still have enough credits for the tiny quotafile
1124  * write.
1125  */
1126 int do_journal_get_write_access(handle_t *handle,
1127 				struct buffer_head *bh)
1128 {
1129 	int dirty = buffer_dirty(bh);
1130 	int ret;
1131 
1132 	if (!buffer_mapped(bh) || buffer_freed(bh))
1133 		return 0;
1134 	/*
1135 	 * __block_write_begin() could have dirtied some buffers. Clean
1136 	 * the dirty bit as jbd2_journal_get_write_access() could complain
1137 	 * otherwise about fs integrity issues. Setting of the dirty bit
1138 	 * by __block_write_begin() isn't a real problem here as we clear
1139 	 * the bit before releasing a page lock and thus writeback cannot
1140 	 * ever write the buffer.
1141 	 */
1142 	if (dirty)
1143 		clear_buffer_dirty(bh);
1144 	BUFFER_TRACE(bh, "get write access");
1145 	ret = ext4_journal_get_write_access(handle, bh);
1146 	if (!ret && dirty)
1147 		ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1148 	return ret;
1149 }
1150 
1151 #ifdef CONFIG_FS_ENCRYPTION
1152 static int ext4_block_write_begin(struct page *page, loff_t pos, unsigned len,
1153 				  get_block_t *get_block)
1154 {
1155 	unsigned from = pos & (PAGE_SIZE - 1);
1156 	unsigned to = from + len;
1157 	struct inode *inode = page->mapping->host;
1158 	unsigned block_start, block_end;
1159 	sector_t block;
1160 	int err = 0;
1161 	unsigned blocksize = inode->i_sb->s_blocksize;
1162 	unsigned bbits;
1163 	struct buffer_head *bh, *head, *wait[2], **wait_bh = wait;
1164 	bool decrypt = false;
1165 
1166 	BUG_ON(!PageLocked(page));
1167 	BUG_ON(from > PAGE_SIZE);
1168 	BUG_ON(to > PAGE_SIZE);
1169 	BUG_ON(from > to);
1170 
1171 	if (!page_has_buffers(page))
1172 		create_empty_buffers(page, blocksize, 0);
1173 	head = page_buffers(page);
1174 	bbits = ilog2(blocksize);
1175 	block = (sector_t)page->index << (PAGE_SHIFT - bbits);
1176 
1177 	for (bh = head, block_start = 0; bh != head || !block_start;
1178 	    block++, block_start = block_end, bh = bh->b_this_page) {
1179 		block_end = block_start + blocksize;
1180 		if (block_end <= from || block_start >= to) {
1181 			if (PageUptodate(page)) {
1182 				if (!buffer_uptodate(bh))
1183 					set_buffer_uptodate(bh);
1184 			}
1185 			continue;
1186 		}
1187 		if (buffer_new(bh))
1188 			clear_buffer_new(bh);
1189 		if (!buffer_mapped(bh)) {
1190 			WARN_ON(bh->b_size != blocksize);
1191 			err = get_block(inode, block, bh, 1);
1192 			if (err)
1193 				break;
1194 			if (buffer_new(bh)) {
1195 				if (PageUptodate(page)) {
1196 					clear_buffer_new(bh);
1197 					set_buffer_uptodate(bh);
1198 					mark_buffer_dirty(bh);
1199 					continue;
1200 				}
1201 				if (block_end > to || block_start < from)
1202 					zero_user_segments(page, to, block_end,
1203 							   block_start, from);
1204 				continue;
1205 			}
1206 		}
1207 		if (PageUptodate(page)) {
1208 			if (!buffer_uptodate(bh))
1209 				set_buffer_uptodate(bh);
1210 			continue;
1211 		}
1212 		if (!buffer_uptodate(bh) && !buffer_delay(bh) &&
1213 		    !buffer_unwritten(bh) &&
1214 		    (block_start < from || block_end > to)) {
1215 			ll_rw_block(REQ_OP_READ, 0, 1, &bh);
1216 			*wait_bh++ = bh;
1217 			decrypt = IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
1218 		}
1219 	}
1220 	/*
1221 	 * If we issued read requests, let them complete.
1222 	 */
1223 	while (wait_bh > wait) {
1224 		wait_on_buffer(*--wait_bh);
1225 		if (!buffer_uptodate(*wait_bh))
1226 			err = -EIO;
1227 	}
1228 	if (unlikely(err))
1229 		page_zero_new_buffers(page, from, to);
1230 	else if (decrypt)
1231 		err = fscrypt_decrypt_page(page->mapping->host, page,
1232 				PAGE_SIZE, 0, page->index);
1233 	return err;
1234 }
1235 #endif
1236 
1237 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1238 			    loff_t pos, unsigned len, unsigned flags,
1239 			    struct page **pagep, void **fsdata)
1240 {
1241 	struct inode *inode = mapping->host;
1242 	int ret, needed_blocks;
1243 	handle_t *handle;
1244 	int retries = 0;
1245 	struct page *page;
1246 	pgoff_t index;
1247 	unsigned from, to;
1248 
1249 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
1250 		return -EIO;
1251 
1252 	trace_ext4_write_begin(inode, pos, len, flags);
1253 	/*
1254 	 * Reserve one block more for addition to orphan list in case
1255 	 * we allocate blocks but write fails for some reason
1256 	 */
1257 	needed_blocks = ext4_writepage_trans_blocks(inode) + 1;
1258 	index = pos >> PAGE_SHIFT;
1259 	from = pos & (PAGE_SIZE - 1);
1260 	to = from + len;
1261 
1262 	if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
1263 		ret = ext4_try_to_write_inline_data(mapping, inode, pos, len,
1264 						    flags, pagep);
1265 		if (ret < 0)
1266 			return ret;
1267 		if (ret == 1)
1268 			return 0;
1269 	}
1270 
1271 	/*
1272 	 * grab_cache_page_write_begin() can take a long time if the
1273 	 * system is thrashing due to memory pressure, or if the page
1274 	 * is being written back.  So grab it first before we start
1275 	 * the transaction handle.  This also allows us to allocate
1276 	 * the page (if needed) without using GFP_NOFS.
1277 	 */
1278 retry_grab:
1279 	page = grab_cache_page_write_begin(mapping, index, flags);
1280 	if (!page)
1281 		return -ENOMEM;
1282 	unlock_page(page);
1283 
1284 retry_journal:
1285 	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
1286 	if (IS_ERR(handle)) {
1287 		put_page(page);
1288 		return PTR_ERR(handle);
1289 	}
1290 
1291 	lock_page(page);
1292 	if (page->mapping != mapping) {
1293 		/* The page got truncated from under us */
1294 		unlock_page(page);
1295 		put_page(page);
1296 		ext4_journal_stop(handle);
1297 		goto retry_grab;
1298 	}
1299 	/* In case writeback began while the page was unlocked */
1300 	wait_for_stable_page(page);
1301 
1302 #ifdef CONFIG_FS_ENCRYPTION
1303 	if (ext4_should_dioread_nolock(inode))
1304 		ret = ext4_block_write_begin(page, pos, len,
1305 					     ext4_get_block_unwritten);
1306 	else
1307 		ret = ext4_block_write_begin(page, pos, len,
1308 					     ext4_get_block);
1309 #else
1310 	if (ext4_should_dioread_nolock(inode))
1311 		ret = __block_write_begin(page, pos, len,
1312 					  ext4_get_block_unwritten);
1313 	else
1314 		ret = __block_write_begin(page, pos, len, ext4_get_block);
1315 #endif
1316 	if (!ret && ext4_should_journal_data(inode)) {
1317 		ret = ext4_walk_page_buffers(handle, page_buffers(page),
1318 					     from, to, NULL,
1319 					     do_journal_get_write_access);
1320 	}
1321 
1322 	if (ret) {
1323 		unlock_page(page);
1324 		/*
1325 		 * __block_write_begin may have instantiated a few blocks
1326 		 * outside i_size.  Trim these off again. Don't need
1327 		 * i_size_read because we hold i_mutex.
1328 		 *
1329 		 * Add inode to orphan list in case we crash before
1330 		 * truncate finishes
1331 		 */
1332 		if (pos + len > inode->i_size && ext4_can_truncate(inode))
1333 			ext4_orphan_add(handle, inode);
1334 
1335 		ext4_journal_stop(handle);
1336 		if (pos + len > inode->i_size) {
1337 			ext4_truncate_failed_write(inode);
1338 			/*
1339 			 * If truncate failed early the inode might
1340 			 * still be on the orphan list; we need to
1341 			 * make sure the inode is removed from the
1342 			 * orphan list in that case.
1343 			 */
1344 			if (inode->i_nlink)
1345 				ext4_orphan_del(NULL, inode);
1346 		}
1347 
1348 		if (ret == -ENOSPC &&
1349 		    ext4_should_retry_alloc(inode->i_sb, &retries))
1350 			goto retry_journal;
1351 		put_page(page);
1352 		return ret;
1353 	}
1354 	*pagep = page;
1355 	return ret;
1356 }
1357 
1358 /* For write_end() in data=journal mode */
1359 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1360 {
1361 	int ret;
1362 	if (!buffer_mapped(bh) || buffer_freed(bh))
1363 		return 0;
1364 	set_buffer_uptodate(bh);
1365 	ret = ext4_handle_dirty_metadata(handle, NULL, bh);
1366 	clear_buffer_meta(bh);
1367 	clear_buffer_prio(bh);
1368 	return ret;
1369 }
1370 
1371 /*
1372  * We need to pick up the new inode size which generic_commit_write gave us
1373  * `file' can be NULL - eg, when called from page_symlink().
1374  *
1375  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1376  * buffers are managed internally.
1377  */
1378 static int ext4_write_end(struct file *file,
1379 			  struct address_space *mapping,
1380 			  loff_t pos, unsigned len, unsigned copied,
1381 			  struct page *page, void *fsdata)
1382 {
1383 	handle_t *handle = ext4_journal_current_handle();
1384 	struct inode *inode = mapping->host;
1385 	loff_t old_size = inode->i_size;
1386 	int ret = 0, ret2;
1387 	int i_size_changed = 0;
1388 	int inline_data = ext4_has_inline_data(inode);
1389 
1390 	trace_ext4_write_end(inode, pos, len, copied);
1391 	if (inline_data) {
1392 		ret = ext4_write_inline_data_end(inode, pos, len,
1393 						 copied, page);
1394 		if (ret < 0) {
1395 			unlock_page(page);
1396 			put_page(page);
1397 			goto errout;
1398 		}
1399 		copied = ret;
1400 	} else
1401 		copied = block_write_end(file, mapping, pos,
1402 					 len, copied, page, fsdata);
1403 	/*
1404 	 * it's important to update i_size while still holding page lock:
1405 	 * page writeout could otherwise come in and zero beyond i_size.
1406 	 */
1407 	i_size_changed = ext4_update_inode_size(inode, pos + copied);
1408 	unlock_page(page);
1409 	put_page(page);
1410 
1411 	if (old_size < pos)
1412 		pagecache_isize_extended(inode, old_size, pos);
1413 	/*
1414 	 * Don't mark the inode dirty under page lock. First, it unnecessarily
1415 	 * makes the holding time of page lock longer. Second, it forces lock
1416 	 * ordering of page lock and transaction start for journaling
1417 	 * filesystems.
1418 	 */
1419 	if (i_size_changed || inline_data)
1420 		ext4_mark_inode_dirty(handle, inode);
1421 
1422 	if (pos + len > inode->i_size && ext4_can_truncate(inode))
1423 		/* if we have allocated more blocks and copied
1424 		 * less. We will have blocks allocated outside
1425 		 * inode->i_size. So truncate them
1426 		 */
1427 		ext4_orphan_add(handle, inode);
1428 errout:
1429 	ret2 = ext4_journal_stop(handle);
1430 	if (!ret)
1431 		ret = ret2;
1432 
1433 	if (pos + len > inode->i_size) {
1434 		ext4_truncate_failed_write(inode);
1435 		/*
1436 		 * If truncate failed early the inode might still be
1437 		 * on the orphan list; we need to make sure the inode
1438 		 * is removed from the orphan list in that case.
1439 		 */
1440 		if (inode->i_nlink)
1441 			ext4_orphan_del(NULL, inode);
1442 	}
1443 
1444 	return ret ? ret : copied;
1445 }
1446 
1447 /*
1448  * This is a private version of page_zero_new_buffers() which doesn't
1449  * set the buffer to be dirty, since in data=journalled mode we need
1450  * to call ext4_handle_dirty_metadata() instead.
1451  */
1452 static void ext4_journalled_zero_new_buffers(handle_t *handle,
1453 					    struct page *page,
1454 					    unsigned from, unsigned to)
1455 {
1456 	unsigned int block_start = 0, block_end;
1457 	struct buffer_head *head, *bh;
1458 
1459 	bh = head = page_buffers(page);
1460 	do {
1461 		block_end = block_start + bh->b_size;
1462 		if (buffer_new(bh)) {
1463 			if (block_end > from && block_start < to) {
1464 				if (!PageUptodate(page)) {
1465 					unsigned start, size;
1466 
1467 					start = max(from, block_start);
1468 					size = min(to, block_end) - start;
1469 
1470 					zero_user(page, start, size);
1471 					write_end_fn(handle, bh);
1472 				}
1473 				clear_buffer_new(bh);
1474 			}
1475 		}
1476 		block_start = block_end;
1477 		bh = bh->b_this_page;
1478 	} while (bh != head);
1479 }
1480 
1481 static int ext4_journalled_write_end(struct file *file,
1482 				     struct address_space *mapping,
1483 				     loff_t pos, unsigned len, unsigned copied,
1484 				     struct page *page, void *fsdata)
1485 {
1486 	handle_t *handle = ext4_journal_current_handle();
1487 	struct inode *inode = mapping->host;
1488 	loff_t old_size = inode->i_size;
1489 	int ret = 0, ret2;
1490 	int partial = 0;
1491 	unsigned from, to;
1492 	int size_changed = 0;
1493 	int inline_data = ext4_has_inline_data(inode);
1494 
1495 	trace_ext4_journalled_write_end(inode, pos, len, copied);
1496 	from = pos & (PAGE_SIZE - 1);
1497 	to = from + len;
1498 
1499 	BUG_ON(!ext4_handle_valid(handle));
1500 
1501 	if (inline_data) {
1502 		ret = ext4_write_inline_data_end(inode, pos, len,
1503 						 copied, page);
1504 		if (ret < 0) {
1505 			unlock_page(page);
1506 			put_page(page);
1507 			goto errout;
1508 		}
1509 		copied = ret;
1510 	} else if (unlikely(copied < len) && !PageUptodate(page)) {
1511 		copied = 0;
1512 		ext4_journalled_zero_new_buffers(handle, page, from, to);
1513 	} else {
1514 		if (unlikely(copied < len))
1515 			ext4_journalled_zero_new_buffers(handle, page,
1516 							 from + copied, to);
1517 		ret = ext4_walk_page_buffers(handle, page_buffers(page), from,
1518 					     from + copied, &partial,
1519 					     write_end_fn);
1520 		if (!partial)
1521 			SetPageUptodate(page);
1522 	}
1523 	size_changed = ext4_update_inode_size(inode, pos + copied);
1524 	ext4_set_inode_state(inode, EXT4_STATE_JDATA);
1525 	EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
1526 	unlock_page(page);
1527 	put_page(page);
1528 
1529 	if (old_size < pos)
1530 		pagecache_isize_extended(inode, old_size, pos);
1531 
1532 	if (size_changed || inline_data) {
1533 		ret2 = ext4_mark_inode_dirty(handle, inode);
1534 		if (!ret)
1535 			ret = ret2;
1536 	}
1537 
1538 	if (pos + len > inode->i_size && ext4_can_truncate(inode))
1539 		/* if we have allocated more blocks and copied
1540 		 * less. We will have blocks allocated outside
1541 		 * inode->i_size. So truncate them
1542 		 */
1543 		ext4_orphan_add(handle, inode);
1544 
1545 errout:
1546 	ret2 = ext4_journal_stop(handle);
1547 	if (!ret)
1548 		ret = ret2;
1549 	if (pos + len > inode->i_size) {
1550 		ext4_truncate_failed_write(inode);
1551 		/*
1552 		 * If truncate failed early the inode might still be
1553 		 * on the orphan list; we need to make sure the inode
1554 		 * is removed from the orphan list in that case.
1555 		 */
1556 		if (inode->i_nlink)
1557 			ext4_orphan_del(NULL, inode);
1558 	}
1559 
1560 	return ret ? ret : copied;
1561 }
1562 
1563 /*
1564  * Reserve space for a single cluster
1565  */
1566 static int ext4_da_reserve_space(struct inode *inode)
1567 {
1568 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1569 	struct ext4_inode_info *ei = EXT4_I(inode);
1570 	int ret;
1571 
1572 	/*
1573 	 * We will charge metadata quota at writeout time; this saves
1574 	 * us from metadata over-estimation, though we may go over by
1575 	 * a small amount in the end.  Here we just reserve for data.
1576 	 */
1577 	ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
1578 	if (ret)
1579 		return ret;
1580 
1581 	spin_lock(&ei->i_block_reservation_lock);
1582 	if (ext4_claim_free_clusters(sbi, 1, 0)) {
1583 		spin_unlock(&ei->i_block_reservation_lock);
1584 		dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
1585 		return -ENOSPC;
1586 	}
1587 	ei->i_reserved_data_blocks++;
1588 	trace_ext4_da_reserve_space(inode);
1589 	spin_unlock(&ei->i_block_reservation_lock);
1590 
1591 	return 0;       /* success */
1592 }
1593 
1594 void ext4_da_release_space(struct inode *inode, int to_free)
1595 {
1596 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1597 	struct ext4_inode_info *ei = EXT4_I(inode);
1598 
1599 	if (!to_free)
1600 		return;		/* Nothing to release, exit */
1601 
1602 	spin_lock(&EXT4_I(inode)->i_block_reservation_lock);
1603 
1604 	trace_ext4_da_release_space(inode, to_free);
1605 	if (unlikely(to_free > ei->i_reserved_data_blocks)) {
1606 		/*
1607 		 * if there aren't enough reserved blocks, then the
1608 		 * counter is messed up somewhere.  Since this
1609 		 * function is called from invalidate page, it's
1610 		 * harmless to return without any action.
1611 		 */
1612 		ext4_warning(inode->i_sb, "ext4_da_release_space: "
1613 			 "ino %lu, to_free %d with only %d reserved "
1614 			 "data blocks", inode->i_ino, to_free,
1615 			 ei->i_reserved_data_blocks);
1616 		WARN_ON(1);
1617 		to_free = ei->i_reserved_data_blocks;
1618 	}
1619 	ei->i_reserved_data_blocks -= to_free;
1620 
1621 	/* update fs dirty data blocks counter */
1622 	percpu_counter_sub(&sbi->s_dirtyclusters_counter, to_free);
1623 
1624 	spin_unlock(&EXT4_I(inode)->i_block_reservation_lock);
1625 
1626 	dquot_release_reservation_block(inode, EXT4_C2B(sbi, to_free));
1627 }
1628 
1629 static void ext4_da_page_release_reservation(struct page *page,
1630 					     unsigned int offset,
1631 					     unsigned int length)
1632 {
1633 	int contiguous_blks = 0;
1634 	struct buffer_head *head, *bh;
1635 	unsigned int curr_off = 0;
1636 	struct inode *inode = page->mapping->host;
1637 	unsigned int stop = offset + length;
1638 	ext4_fsblk_t lblk;
1639 
1640 	BUG_ON(stop > PAGE_SIZE || stop < length);
1641 
1642 	head = page_buffers(page);
1643 	bh = head;
1644 	do {
1645 		unsigned int next_off = curr_off + bh->b_size;
1646 
1647 		if (next_off > stop)
1648 			break;
1649 
1650 		if ((offset <= curr_off) && (buffer_delay(bh))) {
1651 			contiguous_blks++;
1652 			clear_buffer_delay(bh);
1653 		} else if (contiguous_blks) {
1654 			lblk = page->index <<
1655 			       (PAGE_SHIFT - inode->i_blkbits);
1656 			lblk += (curr_off >> inode->i_blkbits) -
1657 				contiguous_blks;
1658 			ext4_es_remove_blks(inode, lblk, contiguous_blks);
1659 			contiguous_blks = 0;
1660 		}
1661 		curr_off = next_off;
1662 	} while ((bh = bh->b_this_page) != head);
1663 
1664 	if (contiguous_blks) {
1665 		lblk = page->index << (PAGE_SHIFT - inode->i_blkbits);
1666 		lblk += (curr_off >> inode->i_blkbits) - contiguous_blks;
1667 		ext4_es_remove_blks(inode, lblk, contiguous_blks);
1668 	}
1669 
1670 }
1671 
1672 /*
1673  * Delayed allocation stuff
1674  */
1675 
1676 struct mpage_da_data {
1677 	struct inode *inode;
1678 	struct writeback_control *wbc;
1679 
1680 	pgoff_t first_page;	/* The first page to write */
1681 	pgoff_t next_page;	/* Current page to examine */
1682 	pgoff_t last_page;	/* Last page to examine */
1683 	/*
1684 	 * Extent to map - this can be after first_page because that can be
1685 	 * fully mapped. We somewhat abuse m_flags to store whether the extent
1686 	 * is delalloc or unwritten.
1687 	 */
1688 	struct ext4_map_blocks map;
1689 	struct ext4_io_submit io_submit;	/* IO submission data */
1690 	unsigned int do_map:1;
1691 };
1692 
1693 static void mpage_release_unused_pages(struct mpage_da_data *mpd,
1694 				       bool invalidate)
1695 {
1696 	int nr_pages, i;
1697 	pgoff_t index, end;
1698 	struct pagevec pvec;
1699 	struct inode *inode = mpd->inode;
1700 	struct address_space *mapping = inode->i_mapping;
1701 
1702 	/* This is necessary when next_page == 0. */
1703 	if (mpd->first_page >= mpd->next_page)
1704 		return;
1705 
1706 	index = mpd->first_page;
1707 	end   = mpd->next_page - 1;
1708 	if (invalidate) {
1709 		ext4_lblk_t start, last;
1710 		start = index << (PAGE_SHIFT - inode->i_blkbits);
1711 		last = end << (PAGE_SHIFT - inode->i_blkbits);
1712 		ext4_es_remove_extent(inode, start, last - start + 1);
1713 	}
1714 
1715 	pagevec_init(&pvec);
1716 	while (index <= end) {
1717 		nr_pages = pagevec_lookup_range(&pvec, mapping, &index, end);
1718 		if (nr_pages == 0)
1719 			break;
1720 		for (i = 0; i < nr_pages; i++) {
1721 			struct page *page = pvec.pages[i];
1722 
1723 			BUG_ON(!PageLocked(page));
1724 			BUG_ON(PageWriteback(page));
1725 			if (invalidate) {
1726 				if (page_mapped(page))
1727 					clear_page_dirty_for_io(page);
1728 				block_invalidatepage(page, 0, PAGE_SIZE);
1729 				ClearPageUptodate(page);
1730 			}
1731 			unlock_page(page);
1732 		}
1733 		pagevec_release(&pvec);
1734 	}
1735 }
1736 
1737 static void ext4_print_free_blocks(struct inode *inode)
1738 {
1739 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1740 	struct super_block *sb = inode->i_sb;
1741 	struct ext4_inode_info *ei = EXT4_I(inode);
1742 
1743 	ext4_msg(sb, KERN_CRIT, "Total free blocks count %lld",
1744 	       EXT4_C2B(EXT4_SB(inode->i_sb),
1745 			ext4_count_free_clusters(sb)));
1746 	ext4_msg(sb, KERN_CRIT, "Free/Dirty block details");
1747 	ext4_msg(sb, KERN_CRIT, "free_blocks=%lld",
1748 	       (long long) EXT4_C2B(EXT4_SB(sb),
1749 		percpu_counter_sum(&sbi->s_freeclusters_counter)));
1750 	ext4_msg(sb, KERN_CRIT, "dirty_blocks=%lld",
1751 	       (long long) EXT4_C2B(EXT4_SB(sb),
1752 		percpu_counter_sum(&sbi->s_dirtyclusters_counter)));
1753 	ext4_msg(sb, KERN_CRIT, "Block reservation details");
1754 	ext4_msg(sb, KERN_CRIT, "i_reserved_data_blocks=%u",
1755 		 ei->i_reserved_data_blocks);
1756 	return;
1757 }
1758 
1759 static int ext4_bh_delay_or_unwritten(handle_t *handle, struct buffer_head *bh)
1760 {
1761 	return (buffer_delay(bh) || buffer_unwritten(bh)) && buffer_dirty(bh);
1762 }
1763 
1764 /*
1765  * ext4_insert_delayed_block - adds a delayed block to the extents status
1766  *                             tree, incrementing the reserved cluster/block
1767  *                             count or making a pending reservation
1768  *                             where needed
1769  *
1770  * @inode - file containing the newly added block
1771  * @lblk - logical block to be added
1772  *
1773  * Returns 0 on success, negative error code on failure.
1774  */
1775 static int ext4_insert_delayed_block(struct inode *inode, ext4_lblk_t lblk)
1776 {
1777 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
1778 	int ret;
1779 	bool allocated = false;
1780 
1781 	/*
1782 	 * If the cluster containing lblk is shared with a delayed,
1783 	 * written, or unwritten extent in a bigalloc file system, it's
1784 	 * already been accounted for and does not need to be reserved.
1785 	 * A pending reservation must be made for the cluster if it's
1786 	 * shared with a written or unwritten extent and doesn't already
1787 	 * have one.  Written and unwritten extents can be purged from the
1788 	 * extents status tree if the system is under memory pressure, so
1789 	 * it's necessary to examine the extent tree if a search of the
1790 	 * extents status tree doesn't get a match.
1791 	 */
1792 	if (sbi->s_cluster_ratio == 1) {
1793 		ret = ext4_da_reserve_space(inode);
1794 		if (ret != 0)   /* ENOSPC */
1795 			goto errout;
1796 	} else {   /* bigalloc */
1797 		if (!ext4_es_scan_clu(inode, &ext4_es_is_delonly, lblk)) {
1798 			if (!ext4_es_scan_clu(inode,
1799 					      &ext4_es_is_mapped, lblk)) {
1800 				ret = ext4_clu_mapped(inode,
1801 						      EXT4_B2C(sbi, lblk));
1802 				if (ret < 0)
1803 					goto errout;
1804 				if (ret == 0) {
1805 					ret = ext4_da_reserve_space(inode);
1806 					if (ret != 0)   /* ENOSPC */
1807 						goto errout;
1808 				} else {
1809 					allocated = true;
1810 				}
1811 			} else {
1812 				allocated = true;
1813 			}
1814 		}
1815 	}
1816 
1817 	ret = ext4_es_insert_delayed_block(inode, lblk, allocated);
1818 
1819 errout:
1820 	return ret;
1821 }
1822 
1823 /*
1824  * This function is grabs code from the very beginning of
1825  * ext4_map_blocks, but assumes that the caller is from delayed write
1826  * time. This function looks up the requested blocks and sets the
1827  * buffer delay bit under the protection of i_data_sem.
1828  */
1829 static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
1830 			      struct ext4_map_blocks *map,
1831 			      struct buffer_head *bh)
1832 {
1833 	struct extent_status es;
1834 	int retval;
1835 	sector_t invalid_block = ~((sector_t) 0xffff);
1836 #ifdef ES_AGGRESSIVE_TEST
1837 	struct ext4_map_blocks orig_map;
1838 
1839 	memcpy(&orig_map, map, sizeof(*map));
1840 #endif
1841 
1842 	if (invalid_block < ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es))
1843 		invalid_block = ~0;
1844 
1845 	map->m_flags = 0;
1846 	ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
1847 		  "logical block %lu\n", inode->i_ino, map->m_len,
1848 		  (unsigned long) map->m_lblk);
1849 
1850 	/* Lookup extent status tree firstly */
1851 	if (ext4_es_lookup_extent(inode, iblock, &es)) {
1852 		if (ext4_es_is_hole(&es)) {
1853 			retval = 0;
1854 			down_read(&EXT4_I(inode)->i_data_sem);
1855 			goto add_delayed;
1856 		}
1857 
1858 		/*
1859 		 * Delayed extent could be allocated by fallocate.
1860 		 * So we need to check it.
1861 		 */
1862 		if (ext4_es_is_delayed(&es) && !ext4_es_is_unwritten(&es)) {
1863 			map_bh(bh, inode->i_sb, invalid_block);
1864 			set_buffer_new(bh);
1865 			set_buffer_delay(bh);
1866 			return 0;
1867 		}
1868 
1869 		map->m_pblk = ext4_es_pblock(&es) + iblock - es.es_lblk;
1870 		retval = es.es_len - (iblock - es.es_lblk);
1871 		if (retval > map->m_len)
1872 			retval = map->m_len;
1873 		map->m_len = retval;
1874 		if (ext4_es_is_written(&es))
1875 			map->m_flags |= EXT4_MAP_MAPPED;
1876 		else if (ext4_es_is_unwritten(&es))
1877 			map->m_flags |= EXT4_MAP_UNWRITTEN;
1878 		else
1879 			BUG_ON(1);
1880 
1881 #ifdef ES_AGGRESSIVE_TEST
1882 		ext4_map_blocks_es_recheck(NULL, inode, map, &orig_map, 0);
1883 #endif
1884 		return retval;
1885 	}
1886 
1887 	/*
1888 	 * Try to see if we can get the block without requesting a new
1889 	 * file system block.
1890 	 */
1891 	down_read(&EXT4_I(inode)->i_data_sem);
1892 	if (ext4_has_inline_data(inode))
1893 		retval = 0;
1894 	else if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
1895 		retval = ext4_ext_map_blocks(NULL, inode, map, 0);
1896 	else
1897 		retval = ext4_ind_map_blocks(NULL, inode, map, 0);
1898 
1899 add_delayed:
1900 	if (retval == 0) {
1901 		int ret;
1902 
1903 		/*
1904 		 * XXX: __block_prepare_write() unmaps passed block,
1905 		 * is it OK?
1906 		 */
1907 
1908 		ret = ext4_insert_delayed_block(inode, map->m_lblk);
1909 		if (ret != 0) {
1910 			retval = ret;
1911 			goto out_unlock;
1912 		}
1913 
1914 		map_bh(bh, inode->i_sb, invalid_block);
1915 		set_buffer_new(bh);
1916 		set_buffer_delay(bh);
1917 	} else if (retval > 0) {
1918 		int ret;
1919 		unsigned int status;
1920 
1921 		if (unlikely(retval != map->m_len)) {
1922 			ext4_warning(inode->i_sb,
1923 				     "ES len assertion failed for inode "
1924 				     "%lu: retval %d != map->m_len %d",
1925 				     inode->i_ino, retval, map->m_len);
1926 			WARN_ON(1);
1927 		}
1928 
1929 		status = map->m_flags & EXT4_MAP_UNWRITTEN ?
1930 				EXTENT_STATUS_UNWRITTEN : EXTENT_STATUS_WRITTEN;
1931 		ret = ext4_es_insert_extent(inode, map->m_lblk, map->m_len,
1932 					    map->m_pblk, status);
1933 		if (ret != 0)
1934 			retval = ret;
1935 	}
1936 
1937 out_unlock:
1938 	up_read((&EXT4_I(inode)->i_data_sem));
1939 
1940 	return retval;
1941 }
1942 
1943 /*
1944  * This is a special get_block_t callback which is used by
1945  * ext4_da_write_begin().  It will either return mapped block or
1946  * reserve space for a single block.
1947  *
1948  * For delayed buffer_head we have BH_Mapped, BH_New, BH_Delay set.
1949  * We also have b_blocknr = -1 and b_bdev initialized properly
1950  *
1951  * For unwritten buffer_head we have BH_Mapped, BH_New, BH_Unwritten set.
1952  * We also have b_blocknr = physicalblock mapping unwritten extent and b_bdev
1953  * initialized properly.
1954  */
1955 int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
1956 			   struct buffer_head *bh, int create)
1957 {
1958 	struct ext4_map_blocks map;
1959 	int ret = 0;
1960 
1961 	BUG_ON(create == 0);
1962 	BUG_ON(bh->b_size != inode->i_sb->s_blocksize);
1963 
1964 	map.m_lblk = iblock;
1965 	map.m_len = 1;
1966 
1967 	/*
1968 	 * first, we need to know whether the block is allocated already
1969 	 * preallocated blocks are unmapped but should treated
1970 	 * the same as allocated blocks.
1971 	 */
1972 	ret = ext4_da_map_blocks(inode, iblock, &map, bh);
1973 	if (ret <= 0)
1974 		return ret;
1975 
1976 	map_bh(bh, inode->i_sb, map.m_pblk);
1977 	ext4_update_bh_state(bh, map.m_flags);
1978 
1979 	if (buffer_unwritten(bh)) {
1980 		/* A delayed write to unwritten bh should be marked
1981 		 * new and mapped.  Mapped ensures that we don't do
1982 		 * get_block multiple times when we write to the same
1983 		 * offset and new ensures that we do proper zero out
1984 		 * for partial write.
1985 		 */
1986 		set_buffer_new(bh);
1987 		set_buffer_mapped(bh);
1988 	}
1989 	return 0;
1990 }
1991 
1992 static int bget_one(handle_t *handle, struct buffer_head *bh)
1993 {
1994 	get_bh(bh);
1995 	return 0;
1996 }
1997 
1998 static int bput_one(handle_t *handle, struct buffer_head *bh)
1999 {
2000 	put_bh(bh);
2001 	return 0;
2002 }
2003 
2004 static int __ext4_journalled_writepage(struct page *page,
2005 				       unsigned int len)
2006 {
2007 	struct address_space *mapping = page->mapping;
2008 	struct inode *inode = mapping->host;
2009 	struct buffer_head *page_bufs = NULL;
2010 	handle_t *handle = NULL;
2011 	int ret = 0, err = 0;
2012 	int inline_data = ext4_has_inline_data(inode);
2013 	struct buffer_head *inode_bh = NULL;
2014 
2015 	ClearPageChecked(page);
2016 
2017 	if (inline_data) {
2018 		BUG_ON(page->index != 0);
2019 		BUG_ON(len > ext4_get_max_inline_size(inode));
2020 		inode_bh = ext4_journalled_write_inline_data(inode, len, page);
2021 		if (inode_bh == NULL)
2022 			goto out;
2023 	} else {
2024 		page_bufs = page_buffers(page);
2025 		if (!page_bufs) {
2026 			BUG();
2027 			goto out;
2028 		}
2029 		ext4_walk_page_buffers(handle, page_bufs, 0, len,
2030 				       NULL, bget_one);
2031 	}
2032 	/*
2033 	 * We need to release the page lock before we start the
2034 	 * journal, so grab a reference so the page won't disappear
2035 	 * out from under us.
2036 	 */
2037 	get_page(page);
2038 	unlock_page(page);
2039 
2040 	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
2041 				    ext4_writepage_trans_blocks(inode));
2042 	if (IS_ERR(handle)) {
2043 		ret = PTR_ERR(handle);
2044 		put_page(page);
2045 		goto out_no_pagelock;
2046 	}
2047 	BUG_ON(!ext4_handle_valid(handle));
2048 
2049 	lock_page(page);
2050 	put_page(page);
2051 	if (page->mapping != mapping) {
2052 		/* The page got truncated from under us */
2053 		ext4_journal_stop(handle);
2054 		ret = 0;
2055 		goto out;
2056 	}
2057 
2058 	if (inline_data) {
2059 		ret = ext4_mark_inode_dirty(handle, inode);
2060 	} else {
2061 		ret = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
2062 					     do_journal_get_write_access);
2063 
2064 		err = ext4_walk_page_buffers(handle, page_bufs, 0, len, NULL,
2065 					     write_end_fn);
2066 	}
2067 	if (ret == 0)
2068 		ret = err;
2069 	EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
2070 	err = ext4_journal_stop(handle);
2071 	if (!ret)
2072 		ret = err;
2073 
2074 	if (!ext4_has_inline_data(inode))
2075 		ext4_walk_page_buffers(NULL, page_bufs, 0, len,
2076 				       NULL, bput_one);
2077 	ext4_set_inode_state(inode, EXT4_STATE_JDATA);
2078 out:
2079 	unlock_page(page);
2080 out_no_pagelock:
2081 	brelse(inode_bh);
2082 	return ret;
2083 }
2084 
2085 /*
2086  * Note that we don't need to start a transaction unless we're journaling data
2087  * because we should have holes filled from ext4_page_mkwrite(). We even don't
2088  * need to file the inode to the transaction's list in ordered mode because if
2089  * we are writing back data added by write(), the inode is already there and if
2090  * we are writing back data modified via mmap(), no one guarantees in which
2091  * transaction the data will hit the disk. In case we are journaling data, we
2092  * cannot start transaction directly because transaction start ranks above page
2093  * lock so we have to do some magic.
2094  *
2095  * This function can get called via...
2096  *   - ext4_writepages after taking page lock (have journal handle)
2097  *   - journal_submit_inode_data_buffers (no journal handle)
2098  *   - shrink_page_list via the kswapd/direct reclaim (no journal handle)
2099  *   - grab_page_cache when doing write_begin (have journal handle)
2100  *
2101  * We don't do any block allocation in this function. If we have page with
2102  * multiple blocks we need to write those buffer_heads that are mapped. This
2103  * is important for mmaped based write. So if we do with blocksize 1K
2104  * truncate(f, 1024);
2105  * a = mmap(f, 0, 4096);
2106  * a[0] = 'a';
2107  * truncate(f, 4096);
2108  * we have in the page first buffer_head mapped via page_mkwrite call back
2109  * but other buffer_heads would be unmapped but dirty (dirty done via the
2110  * do_wp_page). So writepage should write the first block. If we modify
2111  * the mmap area beyond 1024 we will again get a page_fault and the
2112  * page_mkwrite callback will do the block allocation and mark the
2113  * buffer_heads mapped.
2114  *
2115  * We redirty the page if we have any buffer_heads that is either delay or
2116  * unwritten in the page.
2117  *
2118  * We can get recursively called as show below.
2119  *
2120  *	ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
2121  *		ext4_writepage()
2122  *
2123  * But since we don't do any block allocation we should not deadlock.
2124  * Page also have the dirty flag cleared so we don't get recurive page_lock.
2125  */
2126 static int ext4_writepage(struct page *page,
2127 			  struct writeback_control *wbc)
2128 {
2129 	int ret = 0;
2130 	loff_t size;
2131 	unsigned int len;
2132 	struct buffer_head *page_bufs = NULL;
2133 	struct inode *inode = page->mapping->host;
2134 	struct ext4_io_submit io_submit;
2135 	bool keep_towrite = false;
2136 
2137 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) {
2138 		ext4_invalidatepage(page, 0, PAGE_SIZE);
2139 		unlock_page(page);
2140 		return -EIO;
2141 	}
2142 
2143 	trace_ext4_writepage(page);
2144 	size = i_size_read(inode);
2145 	if (page->index == size >> PAGE_SHIFT)
2146 		len = size & ~PAGE_MASK;
2147 	else
2148 		len = PAGE_SIZE;
2149 
2150 	page_bufs = page_buffers(page);
2151 	/*
2152 	 * We cannot do block allocation or other extent handling in this
2153 	 * function. If there are buffers needing that, we have to redirty
2154 	 * the page. But we may reach here when we do a journal commit via
2155 	 * journal_submit_inode_data_buffers() and in that case we must write
2156 	 * allocated buffers to achieve data=ordered mode guarantees.
2157 	 *
2158 	 * Also, if there is only one buffer per page (the fs block
2159 	 * size == the page size), if one buffer needs block
2160 	 * allocation or needs to modify the extent tree to clear the
2161 	 * unwritten flag, we know that the page can't be written at
2162 	 * all, so we might as well refuse the write immediately.
2163 	 * Unfortunately if the block size != page size, we can't as
2164 	 * easily detect this case using ext4_walk_page_buffers(), but
2165 	 * for the extremely common case, this is an optimization that
2166 	 * skips a useless round trip through ext4_bio_write_page().
2167 	 */
2168 	if (ext4_walk_page_buffers(NULL, page_bufs, 0, len, NULL,
2169 				   ext4_bh_delay_or_unwritten)) {
2170 		redirty_page_for_writepage(wbc, page);
2171 		if ((current->flags & PF_MEMALLOC) ||
2172 		    (inode->i_sb->s_blocksize == PAGE_SIZE)) {
2173 			/*
2174 			 * For memory cleaning there's no point in writing only
2175 			 * some buffers. So just bail out. Warn if we came here
2176 			 * from direct reclaim.
2177 			 */
2178 			WARN_ON_ONCE((current->flags & (PF_MEMALLOC|PF_KSWAPD))
2179 							== PF_MEMALLOC);
2180 			unlock_page(page);
2181 			return 0;
2182 		}
2183 		keep_towrite = true;
2184 	}
2185 
2186 	if (PageChecked(page) && ext4_should_journal_data(inode))
2187 		/*
2188 		 * It's mmapped pagecache.  Add buffers and journal it.  There
2189 		 * doesn't seem much point in redirtying the page here.
2190 		 */
2191 		return __ext4_journalled_writepage(page, len);
2192 
2193 	ext4_io_submit_init(&io_submit, wbc);
2194 	io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
2195 	if (!io_submit.io_end) {
2196 		redirty_page_for_writepage(wbc, page);
2197 		unlock_page(page);
2198 		return -ENOMEM;
2199 	}
2200 	ret = ext4_bio_write_page(&io_submit, page, len, wbc, keep_towrite);
2201 	ext4_io_submit(&io_submit);
2202 	/* Drop io_end reference we got from init */
2203 	ext4_put_io_end_defer(io_submit.io_end);
2204 	return ret;
2205 }
2206 
2207 static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
2208 {
2209 	int len;
2210 	loff_t size;
2211 	int err;
2212 
2213 	BUG_ON(page->index != mpd->first_page);
2214 	clear_page_dirty_for_io(page);
2215 	/*
2216 	 * We have to be very careful here!  Nothing protects writeback path
2217 	 * against i_size changes and the page can be writeably mapped into
2218 	 * page tables. So an application can be growing i_size and writing
2219 	 * data through mmap while writeback runs. clear_page_dirty_for_io()
2220 	 * write-protects our page in page tables and the page cannot get
2221 	 * written to again until we release page lock. So only after
2222 	 * clear_page_dirty_for_io() we are safe to sample i_size for
2223 	 * ext4_bio_write_page() to zero-out tail of the written page. We rely
2224 	 * on the barrier provided by TestClearPageDirty in
2225 	 * clear_page_dirty_for_io() to make sure i_size is really sampled only
2226 	 * after page tables are updated.
2227 	 */
2228 	size = i_size_read(mpd->inode);
2229 	if (page->index == size >> PAGE_SHIFT)
2230 		len = size & ~PAGE_MASK;
2231 	else
2232 		len = PAGE_SIZE;
2233 	err = ext4_bio_write_page(&mpd->io_submit, page, len, mpd->wbc, false);
2234 	if (!err)
2235 		mpd->wbc->nr_to_write--;
2236 	mpd->first_page++;
2237 
2238 	return err;
2239 }
2240 
2241 #define BH_FLAGS ((1 << BH_Unwritten) | (1 << BH_Delay))
2242 
2243 /*
2244  * mballoc gives us at most this number of blocks...
2245  * XXX: That seems to be only a limitation of ext4_mb_normalize_request().
2246  * The rest of mballoc seems to handle chunks up to full group size.
2247  */
2248 #define MAX_WRITEPAGES_EXTENT_LEN 2048
2249 
2250 /*
2251  * mpage_add_bh_to_extent - try to add bh to extent of blocks to map
2252  *
2253  * @mpd - extent of blocks
2254  * @lblk - logical number of the block in the file
2255  * @bh - buffer head we want to add to the extent
2256  *
2257  * The function is used to collect contig. blocks in the same state. If the
2258  * buffer doesn't require mapping for writeback and we haven't started the
2259  * extent of buffers to map yet, the function returns 'true' immediately - the
2260  * caller can write the buffer right away. Otherwise the function returns true
2261  * if the block has been added to the extent, false if the block couldn't be
2262  * added.
2263  */
2264 static bool mpage_add_bh_to_extent(struct mpage_da_data *mpd, ext4_lblk_t lblk,
2265 				   struct buffer_head *bh)
2266 {
2267 	struct ext4_map_blocks *map = &mpd->map;
2268 
2269 	/* Buffer that doesn't need mapping for writeback? */
2270 	if (!buffer_dirty(bh) || !buffer_mapped(bh) ||
2271 	    (!buffer_delay(bh) && !buffer_unwritten(bh))) {
2272 		/* So far no extent to map => we write the buffer right away */
2273 		if (map->m_len == 0)
2274 			return true;
2275 		return false;
2276 	}
2277 
2278 	/* First block in the extent? */
2279 	if (map->m_len == 0) {
2280 		/* We cannot map unless handle is started... */
2281 		if (!mpd->do_map)
2282 			return false;
2283 		map->m_lblk = lblk;
2284 		map->m_len = 1;
2285 		map->m_flags = bh->b_state & BH_FLAGS;
2286 		return true;
2287 	}
2288 
2289 	/* Don't go larger than mballoc is willing to allocate */
2290 	if (map->m_len >= MAX_WRITEPAGES_EXTENT_LEN)
2291 		return false;
2292 
2293 	/* Can we merge the block to our big extent? */
2294 	if (lblk == map->m_lblk + map->m_len &&
2295 	    (bh->b_state & BH_FLAGS) == map->m_flags) {
2296 		map->m_len++;
2297 		return true;
2298 	}
2299 	return false;
2300 }
2301 
2302 /*
2303  * mpage_process_page_bufs - submit page buffers for IO or add them to extent
2304  *
2305  * @mpd - extent of blocks for mapping
2306  * @head - the first buffer in the page
2307  * @bh - buffer we should start processing from
2308  * @lblk - logical number of the block in the file corresponding to @bh
2309  *
2310  * Walk through page buffers from @bh upto @head (exclusive) and either submit
2311  * the page for IO if all buffers in this page were mapped and there's no
2312  * accumulated extent of buffers to map or add buffers in the page to the
2313  * extent of buffers to map. The function returns 1 if the caller can continue
2314  * by processing the next page, 0 if it should stop adding buffers to the
2315  * extent to map because we cannot extend it anymore. It can also return value
2316  * < 0 in case of error during IO submission.
2317  */
2318 static int mpage_process_page_bufs(struct mpage_da_data *mpd,
2319 				   struct buffer_head *head,
2320 				   struct buffer_head *bh,
2321 				   ext4_lblk_t lblk)
2322 {
2323 	struct inode *inode = mpd->inode;
2324 	int err;
2325 	ext4_lblk_t blocks = (i_size_read(inode) + i_blocksize(inode) - 1)
2326 							>> inode->i_blkbits;
2327 
2328 	do {
2329 		BUG_ON(buffer_locked(bh));
2330 
2331 		if (lblk >= blocks || !mpage_add_bh_to_extent(mpd, lblk, bh)) {
2332 			/* Found extent to map? */
2333 			if (mpd->map.m_len)
2334 				return 0;
2335 			/* Buffer needs mapping and handle is not started? */
2336 			if (!mpd->do_map)
2337 				return 0;
2338 			/* Everything mapped so far and we hit EOF */
2339 			break;
2340 		}
2341 	} while (lblk++, (bh = bh->b_this_page) != head);
2342 	/* So far everything mapped? Submit the page for IO. */
2343 	if (mpd->map.m_len == 0) {
2344 		err = mpage_submit_page(mpd, head->b_page);
2345 		if (err < 0)
2346 			return err;
2347 	}
2348 	return lblk < blocks;
2349 }
2350 
2351 /*
2352  * mpage_map_buffers - update buffers corresponding to changed extent and
2353  *		       submit fully mapped pages for IO
2354  *
2355  * @mpd - description of extent to map, on return next extent to map
2356  *
2357  * Scan buffers corresponding to changed extent (we expect corresponding pages
2358  * to be already locked) and update buffer state according to new extent state.
2359  * We map delalloc buffers to their physical location, clear unwritten bits,
2360  * and mark buffers as uninit when we perform writes to unwritten extents
2361  * and do extent conversion after IO is finished. If the last page is not fully
2362  * mapped, we update @map to the next extent in the last page that needs
2363  * mapping. Otherwise we submit the page for IO.
2364  */
2365 static int mpage_map_and_submit_buffers(struct mpage_da_data *mpd)
2366 {
2367 	struct pagevec pvec;
2368 	int nr_pages, i;
2369 	struct inode *inode = mpd->inode;
2370 	struct buffer_head *head, *bh;
2371 	int bpp_bits = PAGE_SHIFT - inode->i_blkbits;
2372 	pgoff_t start, end;
2373 	ext4_lblk_t lblk;
2374 	sector_t pblock;
2375 	int err;
2376 
2377 	start = mpd->map.m_lblk >> bpp_bits;
2378 	end = (mpd->map.m_lblk + mpd->map.m_len - 1) >> bpp_bits;
2379 	lblk = start << bpp_bits;
2380 	pblock = mpd->map.m_pblk;
2381 
2382 	pagevec_init(&pvec);
2383 	while (start <= end) {
2384 		nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping,
2385 						&start, end);
2386 		if (nr_pages == 0)
2387 			break;
2388 		for (i = 0; i < nr_pages; i++) {
2389 			struct page *page = pvec.pages[i];
2390 
2391 			bh = head = page_buffers(page);
2392 			do {
2393 				if (lblk < mpd->map.m_lblk)
2394 					continue;
2395 				if (lblk >= mpd->map.m_lblk + mpd->map.m_len) {
2396 					/*
2397 					 * Buffer after end of mapped extent.
2398 					 * Find next buffer in the page to map.
2399 					 */
2400 					mpd->map.m_len = 0;
2401 					mpd->map.m_flags = 0;
2402 					/*
2403 					 * FIXME: If dioread_nolock supports
2404 					 * blocksize < pagesize, we need to make
2405 					 * sure we add size mapped so far to
2406 					 * io_end->size as the following call
2407 					 * can submit the page for IO.
2408 					 */
2409 					err = mpage_process_page_bufs(mpd, head,
2410 								      bh, lblk);
2411 					pagevec_release(&pvec);
2412 					if (err > 0)
2413 						err = 0;
2414 					return err;
2415 				}
2416 				if (buffer_delay(bh)) {
2417 					clear_buffer_delay(bh);
2418 					bh->b_blocknr = pblock++;
2419 				}
2420 				clear_buffer_unwritten(bh);
2421 			} while (lblk++, (bh = bh->b_this_page) != head);
2422 
2423 			/*
2424 			 * FIXME: This is going to break if dioread_nolock
2425 			 * supports blocksize < pagesize as we will try to
2426 			 * convert potentially unmapped parts of inode.
2427 			 */
2428 			mpd->io_submit.io_end->size += PAGE_SIZE;
2429 			/* Page fully mapped - let IO run! */
2430 			err = mpage_submit_page(mpd, page);
2431 			if (err < 0) {
2432 				pagevec_release(&pvec);
2433 				return err;
2434 			}
2435 		}
2436 		pagevec_release(&pvec);
2437 	}
2438 	/* Extent fully mapped and matches with page boundary. We are done. */
2439 	mpd->map.m_len = 0;
2440 	mpd->map.m_flags = 0;
2441 	return 0;
2442 }
2443 
2444 static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
2445 {
2446 	struct inode *inode = mpd->inode;
2447 	struct ext4_map_blocks *map = &mpd->map;
2448 	int get_blocks_flags;
2449 	int err, dioread_nolock;
2450 
2451 	trace_ext4_da_write_pages_extent(inode, map);
2452 	/*
2453 	 * Call ext4_map_blocks() to allocate any delayed allocation blocks, or
2454 	 * to convert an unwritten extent to be initialized (in the case
2455 	 * where we have written into one or more preallocated blocks).  It is
2456 	 * possible that we're going to need more metadata blocks than
2457 	 * previously reserved. However we must not fail because we're in
2458 	 * writeback and there is nothing we can do about it so it might result
2459 	 * in data loss.  So use reserved blocks to allocate metadata if
2460 	 * possible.
2461 	 *
2462 	 * We pass in the magic EXT4_GET_BLOCKS_DELALLOC_RESERVE if
2463 	 * the blocks in question are delalloc blocks.  This indicates
2464 	 * that the blocks and quotas has already been checked when
2465 	 * the data was copied into the page cache.
2466 	 */
2467 	get_blocks_flags = EXT4_GET_BLOCKS_CREATE |
2468 			   EXT4_GET_BLOCKS_METADATA_NOFAIL |
2469 			   EXT4_GET_BLOCKS_IO_SUBMIT;
2470 	dioread_nolock = ext4_should_dioread_nolock(inode);
2471 	if (dioread_nolock)
2472 		get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
2473 	if (map->m_flags & (1 << BH_Delay))
2474 		get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
2475 
2476 	err = ext4_map_blocks(handle, inode, map, get_blocks_flags);
2477 	if (err < 0)
2478 		return err;
2479 	if (dioread_nolock && (map->m_flags & EXT4_MAP_UNWRITTEN)) {
2480 		if (!mpd->io_submit.io_end->handle &&
2481 		    ext4_handle_valid(handle)) {
2482 			mpd->io_submit.io_end->handle = handle->h_rsv_handle;
2483 			handle->h_rsv_handle = NULL;
2484 		}
2485 		ext4_set_io_unwritten_flag(inode, mpd->io_submit.io_end);
2486 	}
2487 
2488 	BUG_ON(map->m_len == 0);
2489 	return 0;
2490 }
2491 
2492 /*
2493  * mpage_map_and_submit_extent - map extent starting at mpd->lblk of length
2494  *				 mpd->len and submit pages underlying it for IO
2495  *
2496  * @handle - handle for journal operations
2497  * @mpd - extent to map
2498  * @give_up_on_write - we set this to true iff there is a fatal error and there
2499  *                     is no hope of writing the data. The caller should discard
2500  *                     dirty pages to avoid infinite loops.
2501  *
2502  * The function maps extent starting at mpd->lblk of length mpd->len. If it is
2503  * delayed, blocks are allocated, if it is unwritten, we may need to convert
2504  * them to initialized or split the described range from larger unwritten
2505  * extent. Note that we need not map all the described range since allocation
2506  * can return less blocks or the range is covered by more unwritten extents. We
2507  * cannot map more because we are limited by reserved transaction credits. On
2508  * the other hand we always make sure that the last touched page is fully
2509  * mapped so that it can be written out (and thus forward progress is
2510  * guaranteed). After mapping we submit all mapped pages for IO.
2511  */
2512 static int mpage_map_and_submit_extent(handle_t *handle,
2513 				       struct mpage_da_data *mpd,
2514 				       bool *give_up_on_write)
2515 {
2516 	struct inode *inode = mpd->inode;
2517 	struct ext4_map_blocks *map = &mpd->map;
2518 	int err;
2519 	loff_t disksize;
2520 	int progress = 0;
2521 
2522 	mpd->io_submit.io_end->offset =
2523 				((loff_t)map->m_lblk) << inode->i_blkbits;
2524 	do {
2525 		err = mpage_map_one_extent(handle, mpd);
2526 		if (err < 0) {
2527 			struct super_block *sb = inode->i_sb;
2528 
2529 			if (ext4_forced_shutdown(EXT4_SB(sb)) ||
2530 			    EXT4_SB(sb)->s_mount_flags & EXT4_MF_FS_ABORTED)
2531 				goto invalidate_dirty_pages;
2532 			/*
2533 			 * Let the uper layers retry transient errors.
2534 			 * In the case of ENOSPC, if ext4_count_free_blocks()
2535 			 * is non-zero, a commit should free up blocks.
2536 			 */
2537 			if ((err == -ENOMEM) ||
2538 			    (err == -ENOSPC && ext4_count_free_clusters(sb))) {
2539 				if (progress)
2540 					goto update_disksize;
2541 				return err;
2542 			}
2543 			ext4_msg(sb, KERN_CRIT,
2544 				 "Delayed block allocation failed for "
2545 				 "inode %lu at logical offset %llu with"
2546 				 " max blocks %u with error %d",
2547 				 inode->i_ino,
2548 				 (unsigned long long)map->m_lblk,
2549 				 (unsigned)map->m_len, -err);
2550 			ext4_msg(sb, KERN_CRIT,
2551 				 "This should not happen!! Data will "
2552 				 "be lost\n");
2553 			if (err == -ENOSPC)
2554 				ext4_print_free_blocks(inode);
2555 		invalidate_dirty_pages:
2556 			*give_up_on_write = true;
2557 			return err;
2558 		}
2559 		progress = 1;
2560 		/*
2561 		 * Update buffer state, submit mapped pages, and get us new
2562 		 * extent to map
2563 		 */
2564 		err = mpage_map_and_submit_buffers(mpd);
2565 		if (err < 0)
2566 			goto update_disksize;
2567 	} while (map->m_len);
2568 
2569 update_disksize:
2570 	/*
2571 	 * Update on-disk size after IO is submitted.  Races with
2572 	 * truncate are avoided by checking i_size under i_data_sem.
2573 	 */
2574 	disksize = ((loff_t)mpd->first_page) << PAGE_SHIFT;
2575 	if (disksize > EXT4_I(inode)->i_disksize) {
2576 		int err2;
2577 		loff_t i_size;
2578 
2579 		down_write(&EXT4_I(inode)->i_data_sem);
2580 		i_size = i_size_read(inode);
2581 		if (disksize > i_size)
2582 			disksize = i_size;
2583 		if (disksize > EXT4_I(inode)->i_disksize)
2584 			EXT4_I(inode)->i_disksize = disksize;
2585 		up_write(&EXT4_I(inode)->i_data_sem);
2586 		err2 = ext4_mark_inode_dirty(handle, inode);
2587 		if (err2)
2588 			ext4_error(inode->i_sb,
2589 				   "Failed to mark inode %lu dirty",
2590 				   inode->i_ino);
2591 		if (!err)
2592 			err = err2;
2593 	}
2594 	return err;
2595 }
2596 
2597 /*
2598  * Calculate the total number of credits to reserve for one writepages
2599  * iteration. This is called from ext4_writepages(). We map an extent of
2600  * up to MAX_WRITEPAGES_EXTENT_LEN blocks and then we go on and finish mapping
2601  * the last partial page. So in total we can map MAX_WRITEPAGES_EXTENT_LEN +
2602  * bpp - 1 blocks in bpp different extents.
2603  */
2604 static int ext4_da_writepages_trans_blocks(struct inode *inode)
2605 {
2606 	int bpp = ext4_journal_blocks_per_page(inode);
2607 
2608 	return ext4_meta_trans_blocks(inode,
2609 				MAX_WRITEPAGES_EXTENT_LEN + bpp - 1, bpp);
2610 }
2611 
2612 /*
2613  * mpage_prepare_extent_to_map - find & lock contiguous range of dirty pages
2614  * 				 and underlying extent to map
2615  *
2616  * @mpd - where to look for pages
2617  *
2618  * Walk dirty pages in the mapping. If they are fully mapped, submit them for
2619  * IO immediately. When we find a page which isn't mapped we start accumulating
2620  * extent of buffers underlying these pages that needs mapping (formed by
2621  * either delayed or unwritten buffers). We also lock the pages containing
2622  * these buffers. The extent found is returned in @mpd structure (starting at
2623  * mpd->lblk with length mpd->len blocks).
2624  *
2625  * Note that this function can attach bios to one io_end structure which are
2626  * neither logically nor physically contiguous. Although it may seem as an
2627  * unnecessary complication, it is actually inevitable in blocksize < pagesize
2628  * case as we need to track IO to all buffers underlying a page in one io_end.
2629  */
2630 static int mpage_prepare_extent_to_map(struct mpage_da_data *mpd)
2631 {
2632 	struct address_space *mapping = mpd->inode->i_mapping;
2633 	struct pagevec pvec;
2634 	unsigned int nr_pages;
2635 	long left = mpd->wbc->nr_to_write;
2636 	pgoff_t index = mpd->first_page;
2637 	pgoff_t end = mpd->last_page;
2638 	xa_mark_t tag;
2639 	int i, err = 0;
2640 	int blkbits = mpd->inode->i_blkbits;
2641 	ext4_lblk_t lblk;
2642 	struct buffer_head *head;
2643 
2644 	if (mpd->wbc->sync_mode == WB_SYNC_ALL || mpd->wbc->tagged_writepages)
2645 		tag = PAGECACHE_TAG_TOWRITE;
2646 	else
2647 		tag = PAGECACHE_TAG_DIRTY;
2648 
2649 	pagevec_init(&pvec);
2650 	mpd->map.m_len = 0;
2651 	mpd->next_page = index;
2652 	while (index <= end) {
2653 		nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index, end,
2654 				tag);
2655 		if (nr_pages == 0)
2656 			goto out;
2657 
2658 		for (i = 0; i < nr_pages; i++) {
2659 			struct page *page = pvec.pages[i];
2660 
2661 			/*
2662 			 * Accumulated enough dirty pages? This doesn't apply
2663 			 * to WB_SYNC_ALL mode. For integrity sync we have to
2664 			 * keep going because someone may be concurrently
2665 			 * dirtying pages, and we might have synced a lot of
2666 			 * newly appeared dirty pages, but have not synced all
2667 			 * of the old dirty pages.
2668 			 */
2669 			if (mpd->wbc->sync_mode == WB_SYNC_NONE && left <= 0)
2670 				goto out;
2671 
2672 			/* If we can't merge this page, we are done. */
2673 			if (mpd->map.m_len > 0 && mpd->next_page != page->index)
2674 				goto out;
2675 
2676 			lock_page(page);
2677 			/*
2678 			 * If the page is no longer dirty, or its mapping no
2679 			 * longer corresponds to inode we are writing (which
2680 			 * means it has been truncated or invalidated), or the
2681 			 * page is already under writeback and we are not doing
2682 			 * a data integrity writeback, skip the page
2683 			 */
2684 			if (!PageDirty(page) ||
2685 			    (PageWriteback(page) &&
2686 			     (mpd->wbc->sync_mode == WB_SYNC_NONE)) ||
2687 			    unlikely(page->mapping != mapping)) {
2688 				unlock_page(page);
2689 				continue;
2690 			}
2691 
2692 			wait_on_page_writeback(page);
2693 			BUG_ON(PageWriteback(page));
2694 
2695 			if (mpd->map.m_len == 0)
2696 				mpd->first_page = page->index;
2697 			mpd->next_page = page->index + 1;
2698 			/* Add all dirty buffers to mpd */
2699 			lblk = ((ext4_lblk_t)page->index) <<
2700 				(PAGE_SHIFT - blkbits);
2701 			head = page_buffers(page);
2702 			err = mpage_process_page_bufs(mpd, head, head, lblk);
2703 			if (err <= 0)
2704 				goto out;
2705 			err = 0;
2706 			left--;
2707 		}
2708 		pagevec_release(&pvec);
2709 		cond_resched();
2710 	}
2711 	return 0;
2712 out:
2713 	pagevec_release(&pvec);
2714 	return err;
2715 }
2716 
2717 static int ext4_writepages(struct address_space *mapping,
2718 			   struct writeback_control *wbc)
2719 {
2720 	pgoff_t	writeback_index = 0;
2721 	long nr_to_write = wbc->nr_to_write;
2722 	int range_whole = 0;
2723 	int cycled = 1;
2724 	handle_t *handle = NULL;
2725 	struct mpage_da_data mpd;
2726 	struct inode *inode = mapping->host;
2727 	int needed_blocks, rsv_blocks = 0, ret = 0;
2728 	struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2729 	bool done;
2730 	struct blk_plug plug;
2731 	bool give_up_on_write = false;
2732 
2733 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
2734 		return -EIO;
2735 
2736 	percpu_down_read(&sbi->s_journal_flag_rwsem);
2737 	trace_ext4_writepages(inode, wbc);
2738 
2739 	/*
2740 	 * No pages to write? This is mainly a kludge to avoid starting
2741 	 * a transaction for special inodes like journal inode on last iput()
2742 	 * because that could violate lock ordering on umount
2743 	 */
2744 	if (!mapping->nrpages || !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
2745 		goto out_writepages;
2746 
2747 	if (ext4_should_journal_data(inode)) {
2748 		ret = generic_writepages(mapping, wbc);
2749 		goto out_writepages;
2750 	}
2751 
2752 	/*
2753 	 * If the filesystem has aborted, it is read-only, so return
2754 	 * right away instead of dumping stack traces later on that
2755 	 * will obscure the real source of the problem.  We test
2756 	 * EXT4_MF_FS_ABORTED instead of sb->s_flag's SB_RDONLY because
2757 	 * the latter could be true if the filesystem is mounted
2758 	 * read-only, and in that case, ext4_writepages should
2759 	 * *never* be called, so if that ever happens, we would want
2760 	 * the stack trace.
2761 	 */
2762 	if (unlikely(ext4_forced_shutdown(EXT4_SB(mapping->host->i_sb)) ||
2763 		     sbi->s_mount_flags & EXT4_MF_FS_ABORTED)) {
2764 		ret = -EROFS;
2765 		goto out_writepages;
2766 	}
2767 
2768 	if (ext4_should_dioread_nolock(inode)) {
2769 		/*
2770 		 * We may need to convert up to one extent per block in
2771 		 * the page and we may dirty the inode.
2772 		 */
2773 		rsv_blocks = 1 + ext4_chunk_trans_blocks(inode,
2774 						PAGE_SIZE >> inode->i_blkbits);
2775 	}
2776 
2777 	/*
2778 	 * If we have inline data and arrive here, it means that
2779 	 * we will soon create the block for the 1st page, so
2780 	 * we'd better clear the inline data here.
2781 	 */
2782 	if (ext4_has_inline_data(inode)) {
2783 		/* Just inode will be modified... */
2784 		handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
2785 		if (IS_ERR(handle)) {
2786 			ret = PTR_ERR(handle);
2787 			goto out_writepages;
2788 		}
2789 		BUG_ON(ext4_test_inode_state(inode,
2790 				EXT4_STATE_MAY_INLINE_DATA));
2791 		ext4_destroy_inline_data(handle, inode);
2792 		ext4_journal_stop(handle);
2793 	}
2794 
2795 	if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
2796 		range_whole = 1;
2797 
2798 	if (wbc->range_cyclic) {
2799 		writeback_index = mapping->writeback_index;
2800 		if (writeback_index)
2801 			cycled = 0;
2802 		mpd.first_page = writeback_index;
2803 		mpd.last_page = -1;
2804 	} else {
2805 		mpd.first_page = wbc->range_start >> PAGE_SHIFT;
2806 		mpd.last_page = wbc->range_end >> PAGE_SHIFT;
2807 	}
2808 
2809 	mpd.inode = inode;
2810 	mpd.wbc = wbc;
2811 	ext4_io_submit_init(&mpd.io_submit, wbc);
2812 retry:
2813 	if (wbc->sync_mode == WB_SYNC_ALL || wbc->tagged_writepages)
2814 		tag_pages_for_writeback(mapping, mpd.first_page, mpd.last_page);
2815 	done = false;
2816 	blk_start_plug(&plug);
2817 
2818 	/*
2819 	 * First writeback pages that don't need mapping - we can avoid
2820 	 * starting a transaction unnecessarily and also avoid being blocked
2821 	 * in the block layer on device congestion while having transaction
2822 	 * started.
2823 	 */
2824 	mpd.do_map = 0;
2825 	mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
2826 	if (!mpd.io_submit.io_end) {
2827 		ret = -ENOMEM;
2828 		goto unplug;
2829 	}
2830 	ret = mpage_prepare_extent_to_map(&mpd);
2831 	/* Unlock pages we didn't use */
2832 	mpage_release_unused_pages(&mpd, false);
2833 	/* Submit prepared bio */
2834 	ext4_io_submit(&mpd.io_submit);
2835 	ext4_put_io_end_defer(mpd.io_submit.io_end);
2836 	mpd.io_submit.io_end = NULL;
2837 	if (ret < 0)
2838 		goto unplug;
2839 
2840 	while (!done && mpd.first_page <= mpd.last_page) {
2841 		/* For each extent of pages we use new io_end */
2842 		mpd.io_submit.io_end = ext4_init_io_end(inode, GFP_KERNEL);
2843 		if (!mpd.io_submit.io_end) {
2844 			ret = -ENOMEM;
2845 			break;
2846 		}
2847 
2848 		/*
2849 		 * We have two constraints: We find one extent to map and we
2850 		 * must always write out whole page (makes a difference when
2851 		 * blocksize < pagesize) so that we don't block on IO when we
2852 		 * try to write out the rest of the page. Journalled mode is
2853 		 * not supported by delalloc.
2854 		 */
2855 		BUG_ON(ext4_should_journal_data(inode));
2856 		needed_blocks = ext4_da_writepages_trans_blocks(inode);
2857 
2858 		/* start a new transaction */
2859 		handle = ext4_journal_start_with_reserve(inode,
2860 				EXT4_HT_WRITE_PAGE, needed_blocks, rsv_blocks);
2861 		if (IS_ERR(handle)) {
2862 			ret = PTR_ERR(handle);
2863 			ext4_msg(inode->i_sb, KERN_CRIT, "%s: jbd2_start: "
2864 			       "%ld pages, ino %lu; err %d", __func__,
2865 				wbc->nr_to_write, inode->i_ino, ret);
2866 			/* Release allocated io_end */
2867 			ext4_put_io_end(mpd.io_submit.io_end);
2868 			mpd.io_submit.io_end = NULL;
2869 			break;
2870 		}
2871 		mpd.do_map = 1;
2872 
2873 		trace_ext4_da_write_pages(inode, mpd.first_page, mpd.wbc);
2874 		ret = mpage_prepare_extent_to_map(&mpd);
2875 		if (!ret) {
2876 			if (mpd.map.m_len)
2877 				ret = mpage_map_and_submit_extent(handle, &mpd,
2878 					&give_up_on_write);
2879 			else {
2880 				/*
2881 				 * We scanned the whole range (or exhausted
2882 				 * nr_to_write), submitted what was mapped and
2883 				 * didn't find anything needing mapping. We are
2884 				 * done.
2885 				 */
2886 				done = true;
2887 			}
2888 		}
2889 		/*
2890 		 * Caution: If the handle is synchronous,
2891 		 * ext4_journal_stop() can wait for transaction commit
2892 		 * to finish which may depend on writeback of pages to
2893 		 * complete or on page lock to be released.  In that
2894 		 * case, we have to wait until after after we have
2895 		 * submitted all the IO, released page locks we hold,
2896 		 * and dropped io_end reference (for extent conversion
2897 		 * to be able to complete) before stopping the handle.
2898 		 */
2899 		if (!ext4_handle_valid(handle) || handle->h_sync == 0) {
2900 			ext4_journal_stop(handle);
2901 			handle = NULL;
2902 			mpd.do_map = 0;
2903 		}
2904 		/* Unlock pages we didn't use */
2905 		mpage_release_unused_pages(&mpd, give_up_on_write);
2906 		/* Submit prepared bio */
2907 		ext4_io_submit(&mpd.io_submit);
2908 
2909 		/*
2910 		 * Drop our io_end reference we got from init. We have
2911 		 * to be careful and use deferred io_end finishing if
2912 		 * we are still holding the transaction as we can
2913 		 * release the last reference to io_end which may end
2914 		 * up doing unwritten extent conversion.
2915 		 */
2916 		if (handle) {
2917 			ext4_put_io_end_defer(mpd.io_submit.io_end);
2918 			ext4_journal_stop(handle);
2919 		} else
2920 			ext4_put_io_end(mpd.io_submit.io_end);
2921 		mpd.io_submit.io_end = NULL;
2922 
2923 		if (ret == -ENOSPC && sbi->s_journal) {
2924 			/*
2925 			 * Commit the transaction which would
2926 			 * free blocks released in the transaction
2927 			 * and try again
2928 			 */
2929 			jbd2_journal_force_commit_nested(sbi->s_journal);
2930 			ret = 0;
2931 			continue;
2932 		}
2933 		/* Fatal error - ENOMEM, EIO... */
2934 		if (ret)
2935 			break;
2936 	}
2937 unplug:
2938 	blk_finish_plug(&plug);
2939 	if (!ret && !cycled && wbc->nr_to_write > 0) {
2940 		cycled = 1;
2941 		mpd.last_page = writeback_index - 1;
2942 		mpd.first_page = 0;
2943 		goto retry;
2944 	}
2945 
2946 	/* Update index */
2947 	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
2948 		/*
2949 		 * Set the writeback_index so that range_cyclic
2950 		 * mode will write it back later
2951 		 */
2952 		mapping->writeback_index = mpd.first_page;
2953 
2954 out_writepages:
2955 	trace_ext4_writepages_result(inode, wbc, ret,
2956 				     nr_to_write - wbc->nr_to_write);
2957 	percpu_up_read(&sbi->s_journal_flag_rwsem);
2958 	return ret;
2959 }
2960 
2961 static int ext4_dax_writepages(struct address_space *mapping,
2962 			       struct writeback_control *wbc)
2963 {
2964 	int ret;
2965 	long nr_to_write = wbc->nr_to_write;
2966 	struct inode *inode = mapping->host;
2967 	struct ext4_sb_info *sbi = EXT4_SB(mapping->host->i_sb);
2968 
2969 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
2970 		return -EIO;
2971 
2972 	percpu_down_read(&sbi->s_journal_flag_rwsem);
2973 	trace_ext4_writepages(inode, wbc);
2974 
2975 	ret = dax_writeback_mapping_range(mapping, inode->i_sb->s_bdev, wbc);
2976 	trace_ext4_writepages_result(inode, wbc, ret,
2977 				     nr_to_write - wbc->nr_to_write);
2978 	percpu_up_read(&sbi->s_journal_flag_rwsem);
2979 	return ret;
2980 }
2981 
2982 static int ext4_nonda_switch(struct super_block *sb)
2983 {
2984 	s64 free_clusters, dirty_clusters;
2985 	struct ext4_sb_info *sbi = EXT4_SB(sb);
2986 
2987 	/*
2988 	 * switch to non delalloc mode if we are running low
2989 	 * on free block. The free block accounting via percpu
2990 	 * counters can get slightly wrong with percpu_counter_batch getting
2991 	 * accumulated on each CPU without updating global counters
2992 	 * Delalloc need an accurate free block accounting. So switch
2993 	 * to non delalloc when we are near to error range.
2994 	 */
2995 	free_clusters =
2996 		percpu_counter_read_positive(&sbi->s_freeclusters_counter);
2997 	dirty_clusters =
2998 		percpu_counter_read_positive(&sbi->s_dirtyclusters_counter);
2999 	/*
3000 	 * Start pushing delalloc when 1/2 of free blocks are dirty.
3001 	 */
3002 	if (dirty_clusters && (free_clusters < 2 * dirty_clusters))
3003 		try_to_writeback_inodes_sb(sb, WB_REASON_FS_FREE_SPACE);
3004 
3005 	if (2 * free_clusters < 3 * dirty_clusters ||
3006 	    free_clusters < (dirty_clusters + EXT4_FREECLUSTERS_WATERMARK)) {
3007 		/*
3008 		 * free block count is less than 150% of dirty blocks
3009 		 * or free blocks is less than watermark
3010 		 */
3011 		return 1;
3012 	}
3013 	return 0;
3014 }
3015 
3016 /* We always reserve for an inode update; the superblock could be there too */
3017 static int ext4_da_write_credits(struct inode *inode, loff_t pos, unsigned len)
3018 {
3019 	if (likely(ext4_has_feature_large_file(inode->i_sb)))
3020 		return 1;
3021 
3022 	if (pos + len <= 0x7fffffffULL)
3023 		return 1;
3024 
3025 	/* We might need to update the superblock to set LARGE_FILE */
3026 	return 2;
3027 }
3028 
3029 static int ext4_da_write_begin(struct file *file, struct address_space *mapping,
3030 			       loff_t pos, unsigned len, unsigned flags,
3031 			       struct page **pagep, void **fsdata)
3032 {
3033 	int ret, retries = 0;
3034 	struct page *page;
3035 	pgoff_t index;
3036 	struct inode *inode = mapping->host;
3037 	handle_t *handle;
3038 
3039 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
3040 		return -EIO;
3041 
3042 	index = pos >> PAGE_SHIFT;
3043 
3044 	if (ext4_nonda_switch(inode->i_sb) ||
3045 	    S_ISLNK(inode->i_mode)) {
3046 		*fsdata = (void *)FALL_BACK_TO_NONDELALLOC;
3047 		return ext4_write_begin(file, mapping, pos,
3048 					len, flags, pagep, fsdata);
3049 	}
3050 	*fsdata = (void *)0;
3051 	trace_ext4_da_write_begin(inode, pos, len, flags);
3052 
3053 	if (ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA)) {
3054 		ret = ext4_da_write_inline_data_begin(mapping, inode,
3055 						      pos, len, flags,
3056 						      pagep, fsdata);
3057 		if (ret < 0)
3058 			return ret;
3059 		if (ret == 1)
3060 			return 0;
3061 	}
3062 
3063 	/*
3064 	 * grab_cache_page_write_begin() can take a long time if the
3065 	 * system is thrashing due to memory pressure, or if the page
3066 	 * is being written back.  So grab it first before we start
3067 	 * the transaction handle.  This also allows us to allocate
3068 	 * the page (if needed) without using GFP_NOFS.
3069 	 */
3070 retry_grab:
3071 	page = grab_cache_page_write_begin(mapping, index, flags);
3072 	if (!page)
3073 		return -ENOMEM;
3074 	unlock_page(page);
3075 
3076 	/*
3077 	 * With delayed allocation, we don't log the i_disksize update
3078 	 * if there is delayed block allocation. But we still need
3079 	 * to journalling the i_disksize update if writes to the end
3080 	 * of file which has an already mapped buffer.
3081 	 */
3082 retry_journal:
3083 	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
3084 				ext4_da_write_credits(inode, pos, len));
3085 	if (IS_ERR(handle)) {
3086 		put_page(page);
3087 		return PTR_ERR(handle);
3088 	}
3089 
3090 	lock_page(page);
3091 	if (page->mapping != mapping) {
3092 		/* The page got truncated from under us */
3093 		unlock_page(page);
3094 		put_page(page);
3095 		ext4_journal_stop(handle);
3096 		goto retry_grab;
3097 	}
3098 	/* In case writeback began while the page was unlocked */
3099 	wait_for_stable_page(page);
3100 
3101 #ifdef CONFIG_FS_ENCRYPTION
3102 	ret = ext4_block_write_begin(page, pos, len,
3103 				     ext4_da_get_block_prep);
3104 #else
3105 	ret = __block_write_begin(page, pos, len, ext4_da_get_block_prep);
3106 #endif
3107 	if (ret < 0) {
3108 		unlock_page(page);
3109 		ext4_journal_stop(handle);
3110 		/*
3111 		 * block_write_begin may have instantiated a few blocks
3112 		 * outside i_size.  Trim these off again. Don't need
3113 		 * i_size_read because we hold i_mutex.
3114 		 */
3115 		if (pos + len > inode->i_size)
3116 			ext4_truncate_failed_write(inode);
3117 
3118 		if (ret == -ENOSPC &&
3119 		    ext4_should_retry_alloc(inode->i_sb, &retries))
3120 			goto retry_journal;
3121 
3122 		put_page(page);
3123 		return ret;
3124 	}
3125 
3126 	*pagep = page;
3127 	return ret;
3128 }
3129 
3130 /*
3131  * Check if we should update i_disksize
3132  * when write to the end of file but not require block allocation
3133  */
3134 static int ext4_da_should_update_i_disksize(struct page *page,
3135 					    unsigned long offset)
3136 {
3137 	struct buffer_head *bh;
3138 	struct inode *inode = page->mapping->host;
3139 	unsigned int idx;
3140 	int i;
3141 
3142 	bh = page_buffers(page);
3143 	idx = offset >> inode->i_blkbits;
3144 
3145 	for (i = 0; i < idx; i++)
3146 		bh = bh->b_this_page;
3147 
3148 	if (!buffer_mapped(bh) || (buffer_delay(bh)) || buffer_unwritten(bh))
3149 		return 0;
3150 	return 1;
3151 }
3152 
3153 static int ext4_da_write_end(struct file *file,
3154 			     struct address_space *mapping,
3155 			     loff_t pos, unsigned len, unsigned copied,
3156 			     struct page *page, void *fsdata)
3157 {
3158 	struct inode *inode = mapping->host;
3159 	int ret = 0, ret2;
3160 	handle_t *handle = ext4_journal_current_handle();
3161 	loff_t new_i_size;
3162 	unsigned long start, end;
3163 	int write_mode = (int)(unsigned long)fsdata;
3164 
3165 	if (write_mode == FALL_BACK_TO_NONDELALLOC)
3166 		return ext4_write_end(file, mapping, pos,
3167 				      len, copied, page, fsdata);
3168 
3169 	trace_ext4_da_write_end(inode, pos, len, copied);
3170 	start = pos & (PAGE_SIZE - 1);
3171 	end = start + copied - 1;
3172 
3173 	/*
3174 	 * generic_write_end() will run mark_inode_dirty() if i_size
3175 	 * changes.  So let's piggyback the i_disksize mark_inode_dirty
3176 	 * into that.
3177 	 */
3178 	new_i_size = pos + copied;
3179 	if (copied && new_i_size > EXT4_I(inode)->i_disksize) {
3180 		if (ext4_has_inline_data(inode) ||
3181 		    ext4_da_should_update_i_disksize(page, end)) {
3182 			ext4_update_i_disksize(inode, new_i_size);
3183 			/* We need to mark inode dirty even if
3184 			 * new_i_size is less that inode->i_size
3185 			 * bu greater than i_disksize.(hint delalloc)
3186 			 */
3187 			ext4_mark_inode_dirty(handle, inode);
3188 		}
3189 	}
3190 
3191 	if (write_mode != CONVERT_INLINE_DATA &&
3192 	    ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) &&
3193 	    ext4_has_inline_data(inode))
3194 		ret2 = ext4_da_write_inline_data_end(inode, pos, len, copied,
3195 						     page);
3196 	else
3197 		ret2 = generic_write_end(file, mapping, pos, len, copied,
3198 							page, fsdata);
3199 
3200 	copied = ret2;
3201 	if (ret2 < 0)
3202 		ret = ret2;
3203 	ret2 = ext4_journal_stop(handle);
3204 	if (!ret)
3205 		ret = ret2;
3206 
3207 	return ret ? ret : copied;
3208 }
3209 
3210 static void ext4_da_invalidatepage(struct page *page, unsigned int offset,
3211 				   unsigned int length)
3212 {
3213 	/*
3214 	 * Drop reserved blocks
3215 	 */
3216 	BUG_ON(!PageLocked(page));
3217 	if (!page_has_buffers(page))
3218 		goto out;
3219 
3220 	ext4_da_page_release_reservation(page, offset, length);
3221 
3222 out:
3223 	ext4_invalidatepage(page, offset, length);
3224 
3225 	return;
3226 }
3227 
3228 /*
3229  * Force all delayed allocation blocks to be allocated for a given inode.
3230  */
3231 int ext4_alloc_da_blocks(struct inode *inode)
3232 {
3233 	trace_ext4_alloc_da_blocks(inode);
3234 
3235 	if (!EXT4_I(inode)->i_reserved_data_blocks)
3236 		return 0;
3237 
3238 	/*
3239 	 * We do something simple for now.  The filemap_flush() will
3240 	 * also start triggering a write of the data blocks, which is
3241 	 * not strictly speaking necessary (and for users of
3242 	 * laptop_mode, not even desirable).  However, to do otherwise
3243 	 * would require replicating code paths in:
3244 	 *
3245 	 * ext4_writepages() ->
3246 	 *    write_cache_pages() ---> (via passed in callback function)
3247 	 *        __mpage_da_writepage() -->
3248 	 *           mpage_add_bh_to_extent()
3249 	 *           mpage_da_map_blocks()
3250 	 *
3251 	 * The problem is that write_cache_pages(), located in
3252 	 * mm/page-writeback.c, marks pages clean in preparation for
3253 	 * doing I/O, which is not desirable if we're not planning on
3254 	 * doing I/O at all.
3255 	 *
3256 	 * We could call write_cache_pages(), and then redirty all of
3257 	 * the pages by calling redirty_page_for_writepage() but that
3258 	 * would be ugly in the extreme.  So instead we would need to
3259 	 * replicate parts of the code in the above functions,
3260 	 * simplifying them because we wouldn't actually intend to
3261 	 * write out the pages, but rather only collect contiguous
3262 	 * logical block extents, call the multi-block allocator, and
3263 	 * then update the buffer heads with the block allocations.
3264 	 *
3265 	 * For now, though, we'll cheat by calling filemap_flush(),
3266 	 * which will map the blocks, and start the I/O, but not
3267 	 * actually wait for the I/O to complete.
3268 	 */
3269 	return filemap_flush(inode->i_mapping);
3270 }
3271 
3272 /*
3273  * bmap() is special.  It gets used by applications such as lilo and by
3274  * the swapper to find the on-disk block of a specific piece of data.
3275  *
3276  * Naturally, this is dangerous if the block concerned is still in the
3277  * journal.  If somebody makes a swapfile on an ext4 data-journaling
3278  * filesystem and enables swap, then they may get a nasty shock when the
3279  * data getting swapped to that swapfile suddenly gets overwritten by
3280  * the original zero's written out previously to the journal and
3281  * awaiting writeback in the kernel's buffer cache.
3282  *
3283  * So, if we see any bmap calls here on a modified, data-journaled file,
3284  * take extra steps to flush any blocks which might be in the cache.
3285  */
3286 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
3287 {
3288 	struct inode *inode = mapping->host;
3289 	journal_t *journal;
3290 	int err;
3291 
3292 	/*
3293 	 * We can get here for an inline file via the FIBMAP ioctl
3294 	 */
3295 	if (ext4_has_inline_data(inode))
3296 		return 0;
3297 
3298 	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY) &&
3299 			test_opt(inode->i_sb, DELALLOC)) {
3300 		/*
3301 		 * With delalloc we want to sync the file
3302 		 * so that we can make sure we allocate
3303 		 * blocks for file
3304 		 */
3305 		filemap_write_and_wait(mapping);
3306 	}
3307 
3308 	if (EXT4_JOURNAL(inode) &&
3309 	    ext4_test_inode_state(inode, EXT4_STATE_JDATA)) {
3310 		/*
3311 		 * This is a REALLY heavyweight approach, but the use of
3312 		 * bmap on dirty files is expected to be extremely rare:
3313 		 * only if we run lilo or swapon on a freshly made file
3314 		 * do we expect this to happen.
3315 		 *
3316 		 * (bmap requires CAP_SYS_RAWIO so this does not
3317 		 * represent an unprivileged user DOS attack --- we'd be
3318 		 * in trouble if mortal users could trigger this path at
3319 		 * will.)
3320 		 *
3321 		 * NB. EXT4_STATE_JDATA is not set on files other than
3322 		 * regular files.  If somebody wants to bmap a directory
3323 		 * or symlink and gets confused because the buffer
3324 		 * hasn't yet been flushed to disk, they deserve
3325 		 * everything they get.
3326 		 */
3327 
3328 		ext4_clear_inode_state(inode, EXT4_STATE_JDATA);
3329 		journal = EXT4_JOURNAL(inode);
3330 		jbd2_journal_lock_updates(journal);
3331 		err = jbd2_journal_flush(journal);
3332 		jbd2_journal_unlock_updates(journal);
3333 
3334 		if (err)
3335 			return 0;
3336 	}
3337 
3338 	return generic_block_bmap(mapping, block, ext4_get_block);
3339 }
3340 
3341 static int ext4_readpage(struct file *file, struct page *page)
3342 {
3343 	int ret = -EAGAIN;
3344 	struct inode *inode = page->mapping->host;
3345 
3346 	trace_ext4_readpage(page);
3347 
3348 	if (ext4_has_inline_data(inode))
3349 		ret = ext4_readpage_inline(inode, page);
3350 
3351 	if (ret == -EAGAIN)
3352 		return ext4_mpage_readpages(page->mapping, NULL, page, 1,
3353 						false);
3354 
3355 	return ret;
3356 }
3357 
3358 static int
3359 ext4_readpages(struct file *file, struct address_space *mapping,
3360 		struct list_head *pages, unsigned nr_pages)
3361 {
3362 	struct inode *inode = mapping->host;
3363 
3364 	/* If the file has inline data, no need to do readpages. */
3365 	if (ext4_has_inline_data(inode))
3366 		return 0;
3367 
3368 	return ext4_mpage_readpages(mapping, pages, NULL, nr_pages, true);
3369 }
3370 
3371 static void ext4_invalidatepage(struct page *page, unsigned int offset,
3372 				unsigned int length)
3373 {
3374 	trace_ext4_invalidatepage(page, offset, length);
3375 
3376 	/* No journalling happens on data buffers when this function is used */
3377 	WARN_ON(page_has_buffers(page) && buffer_jbd(page_buffers(page)));
3378 
3379 	block_invalidatepage(page, offset, length);
3380 }
3381 
3382 static int __ext4_journalled_invalidatepage(struct page *page,
3383 					    unsigned int offset,
3384 					    unsigned int length)
3385 {
3386 	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3387 
3388 	trace_ext4_journalled_invalidatepage(page, offset, length);
3389 
3390 	/*
3391 	 * If it's a full truncate we just forget about the pending dirtying
3392 	 */
3393 	if (offset == 0 && length == PAGE_SIZE)
3394 		ClearPageChecked(page);
3395 
3396 	return jbd2_journal_invalidatepage(journal, page, offset, length);
3397 }
3398 
3399 /* Wrapper for aops... */
3400 static void ext4_journalled_invalidatepage(struct page *page,
3401 					   unsigned int offset,
3402 					   unsigned int length)
3403 {
3404 	WARN_ON(__ext4_journalled_invalidatepage(page, offset, length) < 0);
3405 }
3406 
3407 static int ext4_releasepage(struct page *page, gfp_t wait)
3408 {
3409 	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
3410 
3411 	trace_ext4_releasepage(page);
3412 
3413 	/* Page has dirty journalled data -> cannot release */
3414 	if (PageChecked(page))
3415 		return 0;
3416 	if (journal)
3417 		return jbd2_journal_try_to_free_buffers(journal, page, wait);
3418 	else
3419 		return try_to_free_buffers(page);
3420 }
3421 
3422 static bool ext4_inode_datasync_dirty(struct inode *inode)
3423 {
3424 	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
3425 
3426 	if (journal)
3427 		return !jbd2_transaction_committed(journal,
3428 					EXT4_I(inode)->i_datasync_tid);
3429 	/* Any metadata buffers to write? */
3430 	if (!list_empty(&inode->i_mapping->private_list))
3431 		return true;
3432 	return inode->i_state & I_DIRTY_DATASYNC;
3433 }
3434 
3435 static int ext4_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
3436 			    unsigned flags, struct iomap *iomap)
3437 {
3438 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3439 	unsigned int blkbits = inode->i_blkbits;
3440 	unsigned long first_block, last_block;
3441 	struct ext4_map_blocks map;
3442 	bool delalloc = false;
3443 	int ret;
3444 
3445 	if ((offset >> blkbits) > EXT4_MAX_LOGICAL_BLOCK)
3446 		return -EINVAL;
3447 	first_block = offset >> blkbits;
3448 	last_block = min_t(loff_t, (offset + length - 1) >> blkbits,
3449 			   EXT4_MAX_LOGICAL_BLOCK);
3450 
3451 	if (flags & IOMAP_REPORT) {
3452 		if (ext4_has_inline_data(inode)) {
3453 			ret = ext4_inline_data_iomap(inode, iomap);
3454 			if (ret != -EAGAIN) {
3455 				if (ret == 0 && offset >= iomap->length)
3456 					ret = -ENOENT;
3457 				return ret;
3458 			}
3459 		}
3460 	} else {
3461 		if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
3462 			return -ERANGE;
3463 	}
3464 
3465 	map.m_lblk = first_block;
3466 	map.m_len = last_block - first_block + 1;
3467 
3468 	if (flags & IOMAP_REPORT) {
3469 		ret = ext4_map_blocks(NULL, inode, &map, 0);
3470 		if (ret < 0)
3471 			return ret;
3472 
3473 		if (ret == 0) {
3474 			ext4_lblk_t end = map.m_lblk + map.m_len - 1;
3475 			struct extent_status es;
3476 
3477 			ext4_es_find_extent_range(inode, &ext4_es_is_delayed,
3478 						  map.m_lblk, end, &es);
3479 
3480 			if (!es.es_len || es.es_lblk > end) {
3481 				/* entire range is a hole */
3482 			} else if (es.es_lblk > map.m_lblk) {
3483 				/* range starts with a hole */
3484 				map.m_len = es.es_lblk - map.m_lblk;
3485 			} else {
3486 				ext4_lblk_t offs = 0;
3487 
3488 				if (es.es_lblk < map.m_lblk)
3489 					offs = map.m_lblk - es.es_lblk;
3490 				map.m_lblk = es.es_lblk + offs;
3491 				map.m_len = es.es_len - offs;
3492 				delalloc = true;
3493 			}
3494 		}
3495 	} else if (flags & IOMAP_WRITE) {
3496 		int dio_credits;
3497 		handle_t *handle;
3498 		int retries = 0;
3499 
3500 		/* Trim mapping request to maximum we can map at once for DIO */
3501 		if (map.m_len > DIO_MAX_BLOCKS)
3502 			map.m_len = DIO_MAX_BLOCKS;
3503 		dio_credits = ext4_chunk_trans_blocks(inode, map.m_len);
3504 retry:
3505 		/*
3506 		 * Either we allocate blocks and then we don't get unwritten
3507 		 * extent so we have reserved enough credits, or the blocks
3508 		 * are already allocated and unwritten and in that case
3509 		 * extent conversion fits in the credits as well.
3510 		 */
3511 		handle = ext4_journal_start(inode, EXT4_HT_MAP_BLOCKS,
3512 					    dio_credits);
3513 		if (IS_ERR(handle))
3514 			return PTR_ERR(handle);
3515 
3516 		ret = ext4_map_blocks(handle, inode, &map,
3517 				      EXT4_GET_BLOCKS_CREATE_ZERO);
3518 		if (ret < 0) {
3519 			ext4_journal_stop(handle);
3520 			if (ret == -ENOSPC &&
3521 			    ext4_should_retry_alloc(inode->i_sb, &retries))
3522 				goto retry;
3523 			return ret;
3524 		}
3525 
3526 		/*
3527 		 * If we added blocks beyond i_size, we need to make sure they
3528 		 * will get truncated if we crash before updating i_size in
3529 		 * ext4_iomap_end(). For faults we don't need to do that (and
3530 		 * even cannot because for orphan list operations inode_lock is
3531 		 * required) - if we happen to instantiate block beyond i_size,
3532 		 * it is because we race with truncate which has already added
3533 		 * the inode to the orphan list.
3534 		 */
3535 		if (!(flags & IOMAP_FAULT) && first_block + map.m_len >
3536 		    (i_size_read(inode) + (1 << blkbits) - 1) >> blkbits) {
3537 			int err;
3538 
3539 			err = ext4_orphan_add(handle, inode);
3540 			if (err < 0) {
3541 				ext4_journal_stop(handle);
3542 				return err;
3543 			}
3544 		}
3545 		ext4_journal_stop(handle);
3546 	} else {
3547 		ret = ext4_map_blocks(NULL, inode, &map, 0);
3548 		if (ret < 0)
3549 			return ret;
3550 	}
3551 
3552 	iomap->flags = 0;
3553 	if (ext4_inode_datasync_dirty(inode))
3554 		iomap->flags |= IOMAP_F_DIRTY;
3555 	iomap->bdev = inode->i_sb->s_bdev;
3556 	iomap->dax_dev = sbi->s_daxdev;
3557 	iomap->offset = (u64)first_block << blkbits;
3558 	iomap->length = (u64)map.m_len << blkbits;
3559 
3560 	if (ret == 0) {
3561 		iomap->type = delalloc ? IOMAP_DELALLOC : IOMAP_HOLE;
3562 		iomap->addr = IOMAP_NULL_ADDR;
3563 	} else {
3564 		if (map.m_flags & EXT4_MAP_MAPPED) {
3565 			iomap->type = IOMAP_MAPPED;
3566 		} else if (map.m_flags & EXT4_MAP_UNWRITTEN) {
3567 			iomap->type = IOMAP_UNWRITTEN;
3568 		} else {
3569 			WARN_ON_ONCE(1);
3570 			return -EIO;
3571 		}
3572 		iomap->addr = (u64)map.m_pblk << blkbits;
3573 	}
3574 
3575 	if (map.m_flags & EXT4_MAP_NEW)
3576 		iomap->flags |= IOMAP_F_NEW;
3577 
3578 	return 0;
3579 }
3580 
3581 static int ext4_iomap_end(struct inode *inode, loff_t offset, loff_t length,
3582 			  ssize_t written, unsigned flags, struct iomap *iomap)
3583 {
3584 	int ret = 0;
3585 	handle_t *handle;
3586 	int blkbits = inode->i_blkbits;
3587 	bool truncate = false;
3588 
3589 	if (!(flags & IOMAP_WRITE) || (flags & IOMAP_FAULT))
3590 		return 0;
3591 
3592 	handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
3593 	if (IS_ERR(handle)) {
3594 		ret = PTR_ERR(handle);
3595 		goto orphan_del;
3596 	}
3597 	if (ext4_update_inode_size(inode, offset + written))
3598 		ext4_mark_inode_dirty(handle, inode);
3599 	/*
3600 	 * We may need to truncate allocated but not written blocks beyond EOF.
3601 	 */
3602 	if (iomap->offset + iomap->length >
3603 	    ALIGN(inode->i_size, 1 << blkbits)) {
3604 		ext4_lblk_t written_blk, end_blk;
3605 
3606 		written_blk = (offset + written) >> blkbits;
3607 		end_blk = (offset + length) >> blkbits;
3608 		if (written_blk < end_blk && ext4_can_truncate(inode))
3609 			truncate = true;
3610 	}
3611 	/*
3612 	 * Remove inode from orphan list if we were extending a inode and
3613 	 * everything went fine.
3614 	 */
3615 	if (!truncate && inode->i_nlink &&
3616 	    !list_empty(&EXT4_I(inode)->i_orphan))
3617 		ext4_orphan_del(handle, inode);
3618 	ext4_journal_stop(handle);
3619 	if (truncate) {
3620 		ext4_truncate_failed_write(inode);
3621 orphan_del:
3622 		/*
3623 		 * If truncate failed early the inode might still be on the
3624 		 * orphan list; we need to make sure the inode is removed from
3625 		 * the orphan list in that case.
3626 		 */
3627 		if (inode->i_nlink)
3628 			ext4_orphan_del(NULL, inode);
3629 	}
3630 	return ret;
3631 }
3632 
3633 const struct iomap_ops ext4_iomap_ops = {
3634 	.iomap_begin		= ext4_iomap_begin,
3635 	.iomap_end		= ext4_iomap_end,
3636 };
3637 
3638 static int ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
3639 			    ssize_t size, void *private)
3640 {
3641         ext4_io_end_t *io_end = private;
3642 
3643 	/* if not async direct IO just return */
3644 	if (!io_end)
3645 		return 0;
3646 
3647 	ext_debug("ext4_end_io_dio(): io_end 0x%p "
3648 		  "for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
3649 		  io_end, io_end->inode->i_ino, iocb, offset, size);
3650 
3651 	/*
3652 	 * Error during AIO DIO. We cannot convert unwritten extents as the
3653 	 * data was not written. Just clear the unwritten flag and drop io_end.
3654 	 */
3655 	if (size <= 0) {
3656 		ext4_clear_io_unwritten_flag(io_end);
3657 		size = 0;
3658 	}
3659 	io_end->offset = offset;
3660 	io_end->size = size;
3661 	ext4_put_io_end(io_end);
3662 
3663 	return 0;
3664 }
3665 
3666 /*
3667  * Handling of direct IO writes.
3668  *
3669  * For ext4 extent files, ext4 will do direct-io write even to holes,
3670  * preallocated extents, and those write extend the file, no need to
3671  * fall back to buffered IO.
3672  *
3673  * For holes, we fallocate those blocks, mark them as unwritten
3674  * If those blocks were preallocated, we mark sure they are split, but
3675  * still keep the range to write as unwritten.
3676  *
3677  * The unwritten extents will be converted to written when DIO is completed.
3678  * For async direct IO, since the IO may still pending when return, we
3679  * set up an end_io call back function, which will do the conversion
3680  * when async direct IO completed.
3681  *
3682  * If the O_DIRECT write will extend the file then add this inode to the
3683  * orphan list.  So recovery will truncate it back to the original size
3684  * if the machine crashes during the write.
3685  *
3686  */
3687 static ssize_t ext4_direct_IO_write(struct kiocb *iocb, struct iov_iter *iter)
3688 {
3689 	struct file *file = iocb->ki_filp;
3690 	struct inode *inode = file->f_mapping->host;
3691 	struct ext4_inode_info *ei = EXT4_I(inode);
3692 	ssize_t ret;
3693 	loff_t offset = iocb->ki_pos;
3694 	size_t count = iov_iter_count(iter);
3695 	int overwrite = 0;
3696 	get_block_t *get_block_func = NULL;
3697 	int dio_flags = 0;
3698 	loff_t final_size = offset + count;
3699 	int orphan = 0;
3700 	handle_t *handle;
3701 
3702 	if (final_size > inode->i_size || final_size > ei->i_disksize) {
3703 		/* Credits for sb + inode write */
3704 		handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
3705 		if (IS_ERR(handle)) {
3706 			ret = PTR_ERR(handle);
3707 			goto out;
3708 		}
3709 		ret = ext4_orphan_add(handle, inode);
3710 		if (ret) {
3711 			ext4_journal_stop(handle);
3712 			goto out;
3713 		}
3714 		orphan = 1;
3715 		ext4_update_i_disksize(inode, inode->i_size);
3716 		ext4_journal_stop(handle);
3717 	}
3718 
3719 	BUG_ON(iocb->private == NULL);
3720 
3721 	/*
3722 	 * Make all waiters for direct IO properly wait also for extent
3723 	 * conversion. This also disallows race between truncate() and
3724 	 * overwrite DIO as i_dio_count needs to be incremented under i_mutex.
3725 	 */
3726 	inode_dio_begin(inode);
3727 
3728 	/* If we do a overwrite dio, i_mutex locking can be released */
3729 	overwrite = *((int *)iocb->private);
3730 
3731 	if (overwrite)
3732 		inode_unlock(inode);
3733 
3734 	/*
3735 	 * For extent mapped files we could direct write to holes and fallocate.
3736 	 *
3737 	 * Allocated blocks to fill the hole are marked as unwritten to prevent
3738 	 * parallel buffered read to expose the stale data before DIO complete
3739 	 * the data IO.
3740 	 *
3741 	 * As to previously fallocated extents, ext4 get_block will just simply
3742 	 * mark the buffer mapped but still keep the extents unwritten.
3743 	 *
3744 	 * For non AIO case, we will convert those unwritten extents to written
3745 	 * after return back from blockdev_direct_IO. That way we save us from
3746 	 * allocating io_end structure and also the overhead of offloading
3747 	 * the extent convertion to a workqueue.
3748 	 *
3749 	 * For async DIO, the conversion needs to be deferred when the
3750 	 * IO is completed. The ext4 end_io callback function will be
3751 	 * called to take care of the conversion work.  Here for async
3752 	 * case, we allocate an io_end structure to hook to the iocb.
3753 	 */
3754 	iocb->private = NULL;
3755 	if (overwrite)
3756 		get_block_func = ext4_dio_get_block_overwrite;
3757 	else if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS) ||
3758 		   round_down(offset, i_blocksize(inode)) >= inode->i_size) {
3759 		get_block_func = ext4_dio_get_block;
3760 		dio_flags = DIO_LOCKING | DIO_SKIP_HOLES;
3761 	} else if (is_sync_kiocb(iocb)) {
3762 		get_block_func = ext4_dio_get_block_unwritten_sync;
3763 		dio_flags = DIO_LOCKING;
3764 	} else {
3765 		get_block_func = ext4_dio_get_block_unwritten_async;
3766 		dio_flags = DIO_LOCKING;
3767 	}
3768 	ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
3769 				   get_block_func, ext4_end_io_dio, NULL,
3770 				   dio_flags);
3771 
3772 	if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
3773 						EXT4_STATE_DIO_UNWRITTEN)) {
3774 		int err;
3775 		/*
3776 		 * for non AIO case, since the IO is already
3777 		 * completed, we could do the conversion right here
3778 		 */
3779 		err = ext4_convert_unwritten_extents(NULL, inode,
3780 						     offset, ret);
3781 		if (err < 0)
3782 			ret = err;
3783 		ext4_clear_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
3784 	}
3785 
3786 	inode_dio_end(inode);
3787 	/* take i_mutex locking again if we do a ovewrite dio */
3788 	if (overwrite)
3789 		inode_lock(inode);
3790 
3791 	if (ret < 0 && final_size > inode->i_size)
3792 		ext4_truncate_failed_write(inode);
3793 
3794 	/* Handle extending of i_size after direct IO write */
3795 	if (orphan) {
3796 		int err;
3797 
3798 		/* Credits for sb + inode write */
3799 		handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
3800 		if (IS_ERR(handle)) {
3801 			/*
3802 			 * We wrote the data but cannot extend
3803 			 * i_size. Bail out. In async io case, we do
3804 			 * not return error here because we have
3805 			 * already submmitted the corresponding
3806 			 * bio. Returning error here makes the caller
3807 			 * think that this IO is done and failed
3808 			 * resulting in race with bio's completion
3809 			 * handler.
3810 			 */
3811 			if (!ret)
3812 				ret = PTR_ERR(handle);
3813 			if (inode->i_nlink)
3814 				ext4_orphan_del(NULL, inode);
3815 
3816 			goto out;
3817 		}
3818 		if (inode->i_nlink)
3819 			ext4_orphan_del(handle, inode);
3820 		if (ret > 0) {
3821 			loff_t end = offset + ret;
3822 			if (end > inode->i_size || end > ei->i_disksize) {
3823 				ext4_update_i_disksize(inode, end);
3824 				if (end > inode->i_size)
3825 					i_size_write(inode, end);
3826 				/*
3827 				 * We're going to return a positive `ret'
3828 				 * here due to non-zero-length I/O, so there's
3829 				 * no way of reporting error returns from
3830 				 * ext4_mark_inode_dirty() to userspace.  So
3831 				 * ignore it.
3832 				 */
3833 				ext4_mark_inode_dirty(handle, inode);
3834 			}
3835 		}
3836 		err = ext4_journal_stop(handle);
3837 		if (ret == 0)
3838 			ret = err;
3839 	}
3840 out:
3841 	return ret;
3842 }
3843 
3844 static ssize_t ext4_direct_IO_read(struct kiocb *iocb, struct iov_iter *iter)
3845 {
3846 	struct address_space *mapping = iocb->ki_filp->f_mapping;
3847 	struct inode *inode = mapping->host;
3848 	size_t count = iov_iter_count(iter);
3849 	ssize_t ret;
3850 
3851 	/*
3852 	 * Shared inode_lock is enough for us - it protects against concurrent
3853 	 * writes & truncates and since we take care of writing back page cache,
3854 	 * we are protected against page writeback as well.
3855 	 */
3856 	inode_lock_shared(inode);
3857 	ret = filemap_write_and_wait_range(mapping, iocb->ki_pos,
3858 					   iocb->ki_pos + count - 1);
3859 	if (ret)
3860 		goto out_unlock;
3861 	ret = __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev,
3862 				   iter, ext4_dio_get_block, NULL, NULL, 0);
3863 out_unlock:
3864 	inode_unlock_shared(inode);
3865 	return ret;
3866 }
3867 
3868 static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
3869 {
3870 	struct file *file = iocb->ki_filp;
3871 	struct inode *inode = file->f_mapping->host;
3872 	size_t count = iov_iter_count(iter);
3873 	loff_t offset = iocb->ki_pos;
3874 	ssize_t ret;
3875 
3876 #ifdef CONFIG_FS_ENCRYPTION
3877 	if (IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode))
3878 		return 0;
3879 #endif
3880 
3881 	/*
3882 	 * If we are doing data journalling we don't support O_DIRECT
3883 	 */
3884 	if (ext4_should_journal_data(inode))
3885 		return 0;
3886 
3887 	/* Let buffer I/O handle the inline data case. */
3888 	if (ext4_has_inline_data(inode))
3889 		return 0;
3890 
3891 	trace_ext4_direct_IO_enter(inode, offset, count, iov_iter_rw(iter));
3892 	if (iov_iter_rw(iter) == READ)
3893 		ret = ext4_direct_IO_read(iocb, iter);
3894 	else
3895 		ret = ext4_direct_IO_write(iocb, iter);
3896 	trace_ext4_direct_IO_exit(inode, offset, count, iov_iter_rw(iter), ret);
3897 	return ret;
3898 }
3899 
3900 /*
3901  * Pages can be marked dirty completely asynchronously from ext4's journalling
3902  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
3903  * much here because ->set_page_dirty is called under VFS locks.  The page is
3904  * not necessarily locked.
3905  *
3906  * We cannot just dirty the page and leave attached buffers clean, because the
3907  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
3908  * or jbddirty because all the journalling code will explode.
3909  *
3910  * So what we do is to mark the page "pending dirty" and next time writepage
3911  * is called, propagate that into the buffers appropriately.
3912  */
3913 static int ext4_journalled_set_page_dirty(struct page *page)
3914 {
3915 	SetPageChecked(page);
3916 	return __set_page_dirty_nobuffers(page);
3917 }
3918 
3919 static int ext4_set_page_dirty(struct page *page)
3920 {
3921 	WARN_ON_ONCE(!PageLocked(page) && !PageDirty(page));
3922 	WARN_ON_ONCE(!page_has_buffers(page));
3923 	return __set_page_dirty_buffers(page);
3924 }
3925 
3926 static const struct address_space_operations ext4_aops = {
3927 	.readpage		= ext4_readpage,
3928 	.readpages		= ext4_readpages,
3929 	.writepage		= ext4_writepage,
3930 	.writepages		= ext4_writepages,
3931 	.write_begin		= ext4_write_begin,
3932 	.write_end		= ext4_write_end,
3933 	.set_page_dirty		= ext4_set_page_dirty,
3934 	.bmap			= ext4_bmap,
3935 	.invalidatepage		= ext4_invalidatepage,
3936 	.releasepage		= ext4_releasepage,
3937 	.direct_IO		= ext4_direct_IO,
3938 	.migratepage		= buffer_migrate_page,
3939 	.is_partially_uptodate  = block_is_partially_uptodate,
3940 	.error_remove_page	= generic_error_remove_page,
3941 };
3942 
3943 static const struct address_space_operations ext4_journalled_aops = {
3944 	.readpage		= ext4_readpage,
3945 	.readpages		= ext4_readpages,
3946 	.writepage		= ext4_writepage,
3947 	.writepages		= ext4_writepages,
3948 	.write_begin		= ext4_write_begin,
3949 	.write_end		= ext4_journalled_write_end,
3950 	.set_page_dirty		= ext4_journalled_set_page_dirty,
3951 	.bmap			= ext4_bmap,
3952 	.invalidatepage		= ext4_journalled_invalidatepage,
3953 	.releasepage		= ext4_releasepage,
3954 	.direct_IO		= ext4_direct_IO,
3955 	.is_partially_uptodate  = block_is_partially_uptodate,
3956 	.error_remove_page	= generic_error_remove_page,
3957 };
3958 
3959 static const struct address_space_operations ext4_da_aops = {
3960 	.readpage		= ext4_readpage,
3961 	.readpages		= ext4_readpages,
3962 	.writepage		= ext4_writepage,
3963 	.writepages		= ext4_writepages,
3964 	.write_begin		= ext4_da_write_begin,
3965 	.write_end		= ext4_da_write_end,
3966 	.set_page_dirty		= ext4_set_page_dirty,
3967 	.bmap			= ext4_bmap,
3968 	.invalidatepage		= ext4_da_invalidatepage,
3969 	.releasepage		= ext4_releasepage,
3970 	.direct_IO		= ext4_direct_IO,
3971 	.migratepage		= buffer_migrate_page,
3972 	.is_partially_uptodate  = block_is_partially_uptodate,
3973 	.error_remove_page	= generic_error_remove_page,
3974 };
3975 
3976 static const struct address_space_operations ext4_dax_aops = {
3977 	.writepages		= ext4_dax_writepages,
3978 	.direct_IO		= noop_direct_IO,
3979 	.set_page_dirty		= noop_set_page_dirty,
3980 	.bmap			= ext4_bmap,
3981 	.invalidatepage		= noop_invalidatepage,
3982 };
3983 
3984 void ext4_set_aops(struct inode *inode)
3985 {
3986 	switch (ext4_inode_journal_mode(inode)) {
3987 	case EXT4_INODE_ORDERED_DATA_MODE:
3988 	case EXT4_INODE_WRITEBACK_DATA_MODE:
3989 		break;
3990 	case EXT4_INODE_JOURNAL_DATA_MODE:
3991 		inode->i_mapping->a_ops = &ext4_journalled_aops;
3992 		return;
3993 	default:
3994 		BUG();
3995 	}
3996 	if (IS_DAX(inode))
3997 		inode->i_mapping->a_ops = &ext4_dax_aops;
3998 	else if (test_opt(inode->i_sb, DELALLOC))
3999 		inode->i_mapping->a_ops = &ext4_da_aops;
4000 	else
4001 		inode->i_mapping->a_ops = &ext4_aops;
4002 }
4003 
4004 static int __ext4_block_zero_page_range(handle_t *handle,
4005 		struct address_space *mapping, loff_t from, loff_t length)
4006 {
4007 	ext4_fsblk_t index = from >> PAGE_SHIFT;
4008 	unsigned offset = from & (PAGE_SIZE-1);
4009 	unsigned blocksize, pos;
4010 	ext4_lblk_t iblock;
4011 	struct inode *inode = mapping->host;
4012 	struct buffer_head *bh;
4013 	struct page *page;
4014 	int err = 0;
4015 
4016 	page = find_or_create_page(mapping, from >> PAGE_SHIFT,
4017 				   mapping_gfp_constraint(mapping, ~__GFP_FS));
4018 	if (!page)
4019 		return -ENOMEM;
4020 
4021 	blocksize = inode->i_sb->s_blocksize;
4022 
4023 	iblock = index << (PAGE_SHIFT - inode->i_sb->s_blocksize_bits);
4024 
4025 	if (!page_has_buffers(page))
4026 		create_empty_buffers(page, blocksize, 0);
4027 
4028 	/* Find the buffer that contains "offset" */
4029 	bh = page_buffers(page);
4030 	pos = blocksize;
4031 	while (offset >= pos) {
4032 		bh = bh->b_this_page;
4033 		iblock++;
4034 		pos += blocksize;
4035 	}
4036 	if (buffer_freed(bh)) {
4037 		BUFFER_TRACE(bh, "freed: skip");
4038 		goto unlock;
4039 	}
4040 	if (!buffer_mapped(bh)) {
4041 		BUFFER_TRACE(bh, "unmapped");
4042 		ext4_get_block(inode, iblock, bh, 0);
4043 		/* unmapped? It's a hole - nothing to do */
4044 		if (!buffer_mapped(bh)) {
4045 			BUFFER_TRACE(bh, "still unmapped");
4046 			goto unlock;
4047 		}
4048 	}
4049 
4050 	/* Ok, it's mapped. Make sure it's up-to-date */
4051 	if (PageUptodate(page))
4052 		set_buffer_uptodate(bh);
4053 
4054 	if (!buffer_uptodate(bh)) {
4055 		err = -EIO;
4056 		ll_rw_block(REQ_OP_READ, 0, 1, &bh);
4057 		wait_on_buffer(bh);
4058 		/* Uhhuh. Read error. Complain and punt. */
4059 		if (!buffer_uptodate(bh))
4060 			goto unlock;
4061 		if (S_ISREG(inode->i_mode) && IS_ENCRYPTED(inode)) {
4062 			/* We expect the key to be set. */
4063 			BUG_ON(!fscrypt_has_encryption_key(inode));
4064 			BUG_ON(blocksize != PAGE_SIZE);
4065 			WARN_ON_ONCE(fscrypt_decrypt_page(page->mapping->host,
4066 						page, PAGE_SIZE, 0, page->index));
4067 		}
4068 	}
4069 	if (ext4_should_journal_data(inode)) {
4070 		BUFFER_TRACE(bh, "get write access");
4071 		err = ext4_journal_get_write_access(handle, bh);
4072 		if (err)
4073 			goto unlock;
4074 	}
4075 	zero_user(page, offset, length);
4076 	BUFFER_TRACE(bh, "zeroed end of block");
4077 
4078 	if (ext4_should_journal_data(inode)) {
4079 		err = ext4_handle_dirty_metadata(handle, inode, bh);
4080 	} else {
4081 		err = 0;
4082 		mark_buffer_dirty(bh);
4083 		if (ext4_should_order_data(inode))
4084 			err = ext4_jbd2_inode_add_write(handle, inode);
4085 	}
4086 
4087 unlock:
4088 	unlock_page(page);
4089 	put_page(page);
4090 	return err;
4091 }
4092 
4093 /*
4094  * ext4_block_zero_page_range() zeros out a mapping of length 'length'
4095  * starting from file offset 'from'.  The range to be zero'd must
4096  * be contained with in one block.  If the specified range exceeds
4097  * the end of the block it will be shortened to end of the block
4098  * that cooresponds to 'from'
4099  */
4100 static int ext4_block_zero_page_range(handle_t *handle,
4101 		struct address_space *mapping, loff_t from, loff_t length)
4102 {
4103 	struct inode *inode = mapping->host;
4104 	unsigned offset = from & (PAGE_SIZE-1);
4105 	unsigned blocksize = inode->i_sb->s_blocksize;
4106 	unsigned max = blocksize - (offset & (blocksize - 1));
4107 
4108 	/*
4109 	 * correct length if it does not fall between
4110 	 * 'from' and the end of the block
4111 	 */
4112 	if (length > max || length < 0)
4113 		length = max;
4114 
4115 	if (IS_DAX(inode)) {
4116 		return iomap_zero_range(inode, from, length, NULL,
4117 					&ext4_iomap_ops);
4118 	}
4119 	return __ext4_block_zero_page_range(handle, mapping, from, length);
4120 }
4121 
4122 /*
4123  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
4124  * up to the end of the block which corresponds to `from'.
4125  * This required during truncate. We need to physically zero the tail end
4126  * of that block so it doesn't yield old data if the file is later grown.
4127  */
4128 static int ext4_block_truncate_page(handle_t *handle,
4129 		struct address_space *mapping, loff_t from)
4130 {
4131 	unsigned offset = from & (PAGE_SIZE-1);
4132 	unsigned length;
4133 	unsigned blocksize;
4134 	struct inode *inode = mapping->host;
4135 
4136 	/* If we are processing an encrypted inode during orphan list handling */
4137 	if (IS_ENCRYPTED(inode) && !fscrypt_has_encryption_key(inode))
4138 		return 0;
4139 
4140 	blocksize = inode->i_sb->s_blocksize;
4141 	length = blocksize - (offset & (blocksize - 1));
4142 
4143 	return ext4_block_zero_page_range(handle, mapping, from, length);
4144 }
4145 
4146 int ext4_zero_partial_blocks(handle_t *handle, struct inode *inode,
4147 			     loff_t lstart, loff_t length)
4148 {
4149 	struct super_block *sb = inode->i_sb;
4150 	struct address_space *mapping = inode->i_mapping;
4151 	unsigned partial_start, partial_end;
4152 	ext4_fsblk_t start, end;
4153 	loff_t byte_end = (lstart + length - 1);
4154 	int err = 0;
4155 
4156 	partial_start = lstart & (sb->s_blocksize - 1);
4157 	partial_end = byte_end & (sb->s_blocksize - 1);
4158 
4159 	start = lstart >> sb->s_blocksize_bits;
4160 	end = byte_end >> sb->s_blocksize_bits;
4161 
4162 	/* Handle partial zero within the single block */
4163 	if (start == end &&
4164 	    (partial_start || (partial_end != sb->s_blocksize - 1))) {
4165 		err = ext4_block_zero_page_range(handle, mapping,
4166 						 lstart, length);
4167 		return err;
4168 	}
4169 	/* Handle partial zero out on the start of the range */
4170 	if (partial_start) {
4171 		err = ext4_block_zero_page_range(handle, mapping,
4172 						 lstart, sb->s_blocksize);
4173 		if (err)
4174 			return err;
4175 	}
4176 	/* Handle partial zero out on the end of the range */
4177 	if (partial_end != sb->s_blocksize - 1)
4178 		err = ext4_block_zero_page_range(handle, mapping,
4179 						 byte_end - partial_end,
4180 						 partial_end + 1);
4181 	return err;
4182 }
4183 
4184 int ext4_can_truncate(struct inode *inode)
4185 {
4186 	if (S_ISREG(inode->i_mode))
4187 		return 1;
4188 	if (S_ISDIR(inode->i_mode))
4189 		return 1;
4190 	if (S_ISLNK(inode->i_mode))
4191 		return !ext4_inode_is_fast_symlink(inode);
4192 	return 0;
4193 }
4194 
4195 /*
4196  * We have to make sure i_disksize gets properly updated before we truncate
4197  * page cache due to hole punching or zero range. Otherwise i_disksize update
4198  * can get lost as it may have been postponed to submission of writeback but
4199  * that will never happen after we truncate page cache.
4200  */
4201 int ext4_update_disksize_before_punch(struct inode *inode, loff_t offset,
4202 				      loff_t len)
4203 {
4204 	handle_t *handle;
4205 	loff_t size = i_size_read(inode);
4206 
4207 	WARN_ON(!inode_is_locked(inode));
4208 	if (offset > size || offset + len < size)
4209 		return 0;
4210 
4211 	if (EXT4_I(inode)->i_disksize >= size)
4212 		return 0;
4213 
4214 	handle = ext4_journal_start(inode, EXT4_HT_MISC, 1);
4215 	if (IS_ERR(handle))
4216 		return PTR_ERR(handle);
4217 	ext4_update_i_disksize(inode, size);
4218 	ext4_mark_inode_dirty(handle, inode);
4219 	ext4_journal_stop(handle);
4220 
4221 	return 0;
4222 }
4223 
4224 static void ext4_wait_dax_page(struct ext4_inode_info *ei)
4225 {
4226 	up_write(&ei->i_mmap_sem);
4227 	schedule();
4228 	down_write(&ei->i_mmap_sem);
4229 }
4230 
4231 int ext4_break_layouts(struct inode *inode)
4232 {
4233 	struct ext4_inode_info *ei = EXT4_I(inode);
4234 	struct page *page;
4235 	int error;
4236 
4237 	if (WARN_ON_ONCE(!rwsem_is_locked(&ei->i_mmap_sem)))
4238 		return -EINVAL;
4239 
4240 	do {
4241 		page = dax_layout_busy_page(inode->i_mapping);
4242 		if (!page)
4243 			return 0;
4244 
4245 		error = ___wait_var_event(&page->_refcount,
4246 				atomic_read(&page->_refcount) == 1,
4247 				TASK_INTERRUPTIBLE, 0, 0,
4248 				ext4_wait_dax_page(ei));
4249 	} while (error == 0);
4250 
4251 	return error;
4252 }
4253 
4254 /*
4255  * ext4_punch_hole: punches a hole in a file by releasing the blocks
4256  * associated with the given offset and length
4257  *
4258  * @inode:  File inode
4259  * @offset: The offset where the hole will begin
4260  * @len:    The length of the hole
4261  *
4262  * Returns: 0 on success or negative on failure
4263  */
4264 
4265 int ext4_punch_hole(struct inode *inode, loff_t offset, loff_t length)
4266 {
4267 	struct super_block *sb = inode->i_sb;
4268 	ext4_lblk_t first_block, stop_block;
4269 	struct address_space *mapping = inode->i_mapping;
4270 	loff_t first_block_offset, last_block_offset;
4271 	handle_t *handle;
4272 	unsigned int credits;
4273 	int ret = 0;
4274 
4275 	if (!S_ISREG(inode->i_mode))
4276 		return -EOPNOTSUPP;
4277 
4278 	trace_ext4_punch_hole(inode, offset, length, 0);
4279 
4280 	/*
4281 	 * Write out all dirty pages to avoid race conditions
4282 	 * Then release them.
4283 	 */
4284 	if (mapping_tagged(mapping, PAGECACHE_TAG_DIRTY)) {
4285 		ret = filemap_write_and_wait_range(mapping, offset,
4286 						   offset + length - 1);
4287 		if (ret)
4288 			return ret;
4289 	}
4290 
4291 	inode_lock(inode);
4292 
4293 	/* No need to punch hole beyond i_size */
4294 	if (offset >= inode->i_size)
4295 		goto out_mutex;
4296 
4297 	/*
4298 	 * If the hole extends beyond i_size, set the hole
4299 	 * to end after the page that contains i_size
4300 	 */
4301 	if (offset + length > inode->i_size) {
4302 		length = inode->i_size +
4303 		   PAGE_SIZE - (inode->i_size & (PAGE_SIZE - 1)) -
4304 		   offset;
4305 	}
4306 
4307 	if (offset & (sb->s_blocksize - 1) ||
4308 	    (offset + length) & (sb->s_blocksize - 1)) {
4309 		/*
4310 		 * Attach jinode to inode for jbd2 if we do any zeroing of
4311 		 * partial block
4312 		 */
4313 		ret = ext4_inode_attach_jinode(inode);
4314 		if (ret < 0)
4315 			goto out_mutex;
4316 
4317 	}
4318 
4319 	/* Wait all existing dio workers, newcomers will block on i_mutex */
4320 	inode_dio_wait(inode);
4321 
4322 	/*
4323 	 * Prevent page faults from reinstantiating pages we have released from
4324 	 * page cache.
4325 	 */
4326 	down_write(&EXT4_I(inode)->i_mmap_sem);
4327 
4328 	ret = ext4_break_layouts(inode);
4329 	if (ret)
4330 		goto out_dio;
4331 
4332 	first_block_offset = round_up(offset, sb->s_blocksize);
4333 	last_block_offset = round_down((offset + length), sb->s_blocksize) - 1;
4334 
4335 	/* Now release the pages and zero block aligned part of pages*/
4336 	if (last_block_offset > first_block_offset) {
4337 		ret = ext4_update_disksize_before_punch(inode, offset, length);
4338 		if (ret)
4339 			goto out_dio;
4340 		truncate_pagecache_range(inode, first_block_offset,
4341 					 last_block_offset);
4342 	}
4343 
4344 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4345 		credits = ext4_writepage_trans_blocks(inode);
4346 	else
4347 		credits = ext4_blocks_for_truncate(inode);
4348 	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
4349 	if (IS_ERR(handle)) {
4350 		ret = PTR_ERR(handle);
4351 		ext4_std_error(sb, ret);
4352 		goto out_dio;
4353 	}
4354 
4355 	ret = ext4_zero_partial_blocks(handle, inode, offset,
4356 				       length);
4357 	if (ret)
4358 		goto out_stop;
4359 
4360 	first_block = (offset + sb->s_blocksize - 1) >>
4361 		EXT4_BLOCK_SIZE_BITS(sb);
4362 	stop_block = (offset + length) >> EXT4_BLOCK_SIZE_BITS(sb);
4363 
4364 	/* If there are blocks to remove, do it */
4365 	if (stop_block > first_block) {
4366 
4367 		down_write(&EXT4_I(inode)->i_data_sem);
4368 		ext4_discard_preallocations(inode);
4369 
4370 		ret = ext4_es_remove_extent(inode, first_block,
4371 					    stop_block - first_block);
4372 		if (ret) {
4373 			up_write(&EXT4_I(inode)->i_data_sem);
4374 			goto out_stop;
4375 		}
4376 
4377 		if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4378 			ret = ext4_ext_remove_space(inode, first_block,
4379 						    stop_block - 1);
4380 		else
4381 			ret = ext4_ind_remove_space(handle, inode, first_block,
4382 						    stop_block);
4383 
4384 		up_write(&EXT4_I(inode)->i_data_sem);
4385 	}
4386 	if (IS_SYNC(inode))
4387 		ext4_handle_sync(handle);
4388 
4389 	inode->i_mtime = inode->i_ctime = current_time(inode);
4390 	ext4_mark_inode_dirty(handle, inode);
4391 	if (ret >= 0)
4392 		ext4_update_inode_fsync_trans(handle, inode, 1);
4393 out_stop:
4394 	ext4_journal_stop(handle);
4395 out_dio:
4396 	up_write(&EXT4_I(inode)->i_mmap_sem);
4397 out_mutex:
4398 	inode_unlock(inode);
4399 	return ret;
4400 }
4401 
4402 int ext4_inode_attach_jinode(struct inode *inode)
4403 {
4404 	struct ext4_inode_info *ei = EXT4_I(inode);
4405 	struct jbd2_inode *jinode;
4406 
4407 	if (ei->jinode || !EXT4_SB(inode->i_sb)->s_journal)
4408 		return 0;
4409 
4410 	jinode = jbd2_alloc_inode(GFP_KERNEL);
4411 	spin_lock(&inode->i_lock);
4412 	if (!ei->jinode) {
4413 		if (!jinode) {
4414 			spin_unlock(&inode->i_lock);
4415 			return -ENOMEM;
4416 		}
4417 		ei->jinode = jinode;
4418 		jbd2_journal_init_jbd_inode(ei->jinode, inode);
4419 		jinode = NULL;
4420 	}
4421 	spin_unlock(&inode->i_lock);
4422 	if (unlikely(jinode != NULL))
4423 		jbd2_free_inode(jinode);
4424 	return 0;
4425 }
4426 
4427 /*
4428  * ext4_truncate()
4429  *
4430  * We block out ext4_get_block() block instantiations across the entire
4431  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
4432  * simultaneously on behalf of the same inode.
4433  *
4434  * As we work through the truncate and commit bits of it to the journal there
4435  * is one core, guiding principle: the file's tree must always be consistent on
4436  * disk.  We must be able to restart the truncate after a crash.
4437  *
4438  * The file's tree may be transiently inconsistent in memory (although it
4439  * probably isn't), but whenever we close off and commit a journal transaction,
4440  * the contents of (the filesystem + the journal) must be consistent and
4441  * restartable.  It's pretty simple, really: bottom up, right to left (although
4442  * left-to-right works OK too).
4443  *
4444  * Note that at recovery time, journal replay occurs *before* the restart of
4445  * truncate against the orphan inode list.
4446  *
4447  * The committed inode has the new, desired i_size (which is the same as
4448  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
4449  * that this inode's truncate did not complete and it will again call
4450  * ext4_truncate() to have another go.  So there will be instantiated blocks
4451  * to the right of the truncation point in a crashed ext4 filesystem.  But
4452  * that's fine - as long as they are linked from the inode, the post-crash
4453  * ext4_truncate() run will find them and release them.
4454  */
4455 int ext4_truncate(struct inode *inode)
4456 {
4457 	struct ext4_inode_info *ei = EXT4_I(inode);
4458 	unsigned int credits;
4459 	int err = 0;
4460 	handle_t *handle;
4461 	struct address_space *mapping = inode->i_mapping;
4462 
4463 	/*
4464 	 * There is a possibility that we're either freeing the inode
4465 	 * or it's a completely new inode. In those cases we might not
4466 	 * have i_mutex locked because it's not necessary.
4467 	 */
4468 	if (!(inode->i_state & (I_NEW|I_FREEING)))
4469 		WARN_ON(!inode_is_locked(inode));
4470 	trace_ext4_truncate_enter(inode);
4471 
4472 	if (!ext4_can_truncate(inode))
4473 		return 0;
4474 
4475 	ext4_clear_inode_flag(inode, EXT4_INODE_EOFBLOCKS);
4476 
4477 	if (inode->i_size == 0 && !test_opt(inode->i_sb, NO_AUTO_DA_ALLOC))
4478 		ext4_set_inode_state(inode, EXT4_STATE_DA_ALLOC_CLOSE);
4479 
4480 	if (ext4_has_inline_data(inode)) {
4481 		int has_inline = 1;
4482 
4483 		err = ext4_inline_data_truncate(inode, &has_inline);
4484 		if (err)
4485 			return err;
4486 		if (has_inline)
4487 			return 0;
4488 	}
4489 
4490 	/* If we zero-out tail of the page, we have to create jinode for jbd2 */
4491 	if (inode->i_size & (inode->i_sb->s_blocksize - 1)) {
4492 		if (ext4_inode_attach_jinode(inode) < 0)
4493 			return 0;
4494 	}
4495 
4496 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4497 		credits = ext4_writepage_trans_blocks(inode);
4498 	else
4499 		credits = ext4_blocks_for_truncate(inode);
4500 
4501 	handle = ext4_journal_start(inode, EXT4_HT_TRUNCATE, credits);
4502 	if (IS_ERR(handle))
4503 		return PTR_ERR(handle);
4504 
4505 	if (inode->i_size & (inode->i_sb->s_blocksize - 1))
4506 		ext4_block_truncate_page(handle, mapping, inode->i_size);
4507 
4508 	/*
4509 	 * We add the inode to the orphan list, so that if this
4510 	 * truncate spans multiple transactions, and we crash, we will
4511 	 * resume the truncate when the filesystem recovers.  It also
4512 	 * marks the inode dirty, to catch the new size.
4513 	 *
4514 	 * Implication: the file must always be in a sane, consistent
4515 	 * truncatable state while each transaction commits.
4516 	 */
4517 	err = ext4_orphan_add(handle, inode);
4518 	if (err)
4519 		goto out_stop;
4520 
4521 	down_write(&EXT4_I(inode)->i_data_sem);
4522 
4523 	ext4_discard_preallocations(inode);
4524 
4525 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
4526 		err = ext4_ext_truncate(handle, inode);
4527 	else
4528 		ext4_ind_truncate(handle, inode);
4529 
4530 	up_write(&ei->i_data_sem);
4531 	if (err)
4532 		goto out_stop;
4533 
4534 	if (IS_SYNC(inode))
4535 		ext4_handle_sync(handle);
4536 
4537 out_stop:
4538 	/*
4539 	 * If this was a simple ftruncate() and the file will remain alive,
4540 	 * then we need to clear up the orphan record which we created above.
4541 	 * However, if this was a real unlink then we were called by
4542 	 * ext4_evict_inode(), and we allow that function to clean up the
4543 	 * orphan info for us.
4544 	 */
4545 	if (inode->i_nlink)
4546 		ext4_orphan_del(handle, inode);
4547 
4548 	inode->i_mtime = inode->i_ctime = current_time(inode);
4549 	ext4_mark_inode_dirty(handle, inode);
4550 	ext4_journal_stop(handle);
4551 
4552 	trace_ext4_truncate_exit(inode);
4553 	return err;
4554 }
4555 
4556 /*
4557  * ext4_get_inode_loc returns with an extra refcount against the inode's
4558  * underlying buffer_head on success. If 'in_mem' is true, we have all
4559  * data in memory that is needed to recreate the on-disk version of this
4560  * inode.
4561  */
4562 static int __ext4_get_inode_loc(struct inode *inode,
4563 				struct ext4_iloc *iloc, int in_mem)
4564 {
4565 	struct ext4_group_desc	*gdp;
4566 	struct buffer_head	*bh;
4567 	struct super_block	*sb = inode->i_sb;
4568 	ext4_fsblk_t		block;
4569 	int			inodes_per_block, inode_offset;
4570 
4571 	iloc->bh = NULL;
4572 	if (inode->i_ino < EXT4_ROOT_INO ||
4573 	    inode->i_ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))
4574 		return -EFSCORRUPTED;
4575 
4576 	iloc->block_group = (inode->i_ino - 1) / EXT4_INODES_PER_GROUP(sb);
4577 	gdp = ext4_get_group_desc(sb, iloc->block_group, NULL);
4578 	if (!gdp)
4579 		return -EIO;
4580 
4581 	/*
4582 	 * Figure out the offset within the block group inode table
4583 	 */
4584 	inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
4585 	inode_offset = ((inode->i_ino - 1) %
4586 			EXT4_INODES_PER_GROUP(sb));
4587 	block = ext4_inode_table(sb, gdp) + (inode_offset / inodes_per_block);
4588 	iloc->offset = (inode_offset % inodes_per_block) * EXT4_INODE_SIZE(sb);
4589 
4590 	bh = sb_getblk(sb, block);
4591 	if (unlikely(!bh))
4592 		return -ENOMEM;
4593 	if (!buffer_uptodate(bh)) {
4594 		lock_buffer(bh);
4595 
4596 		/*
4597 		 * If the buffer has the write error flag, we have failed
4598 		 * to write out another inode in the same block.  In this
4599 		 * case, we don't have to read the block because we may
4600 		 * read the old inode data successfully.
4601 		 */
4602 		if (buffer_write_io_error(bh) && !buffer_uptodate(bh))
4603 			set_buffer_uptodate(bh);
4604 
4605 		if (buffer_uptodate(bh)) {
4606 			/* someone brought it uptodate while we waited */
4607 			unlock_buffer(bh);
4608 			goto has_buffer;
4609 		}
4610 
4611 		/*
4612 		 * If we have all information of the inode in memory and this
4613 		 * is the only valid inode in the block, we need not read the
4614 		 * block.
4615 		 */
4616 		if (in_mem) {
4617 			struct buffer_head *bitmap_bh;
4618 			int i, start;
4619 
4620 			start = inode_offset & ~(inodes_per_block - 1);
4621 
4622 			/* Is the inode bitmap in cache? */
4623 			bitmap_bh = sb_getblk(sb, ext4_inode_bitmap(sb, gdp));
4624 			if (unlikely(!bitmap_bh))
4625 				goto make_io;
4626 
4627 			/*
4628 			 * If the inode bitmap isn't in cache then the
4629 			 * optimisation may end up performing two reads instead
4630 			 * of one, so skip it.
4631 			 */
4632 			if (!buffer_uptodate(bitmap_bh)) {
4633 				brelse(bitmap_bh);
4634 				goto make_io;
4635 			}
4636 			for (i = start; i < start + inodes_per_block; i++) {
4637 				if (i == inode_offset)
4638 					continue;
4639 				if (ext4_test_bit(i, bitmap_bh->b_data))
4640 					break;
4641 			}
4642 			brelse(bitmap_bh);
4643 			if (i == start + inodes_per_block) {
4644 				/* all other inodes are free, so skip I/O */
4645 				memset(bh->b_data, 0, bh->b_size);
4646 				set_buffer_uptodate(bh);
4647 				unlock_buffer(bh);
4648 				goto has_buffer;
4649 			}
4650 		}
4651 
4652 make_io:
4653 		/*
4654 		 * If we need to do any I/O, try to pre-readahead extra
4655 		 * blocks from the inode table.
4656 		 */
4657 		if (EXT4_SB(sb)->s_inode_readahead_blks) {
4658 			ext4_fsblk_t b, end, table;
4659 			unsigned num;
4660 			__u32 ra_blks = EXT4_SB(sb)->s_inode_readahead_blks;
4661 
4662 			table = ext4_inode_table(sb, gdp);
4663 			/* s_inode_readahead_blks is always a power of 2 */
4664 			b = block & ~((ext4_fsblk_t) ra_blks - 1);
4665 			if (table > b)
4666 				b = table;
4667 			end = b + ra_blks;
4668 			num = EXT4_INODES_PER_GROUP(sb);
4669 			if (ext4_has_group_desc_csum(sb))
4670 				num -= ext4_itable_unused_count(sb, gdp);
4671 			table += num / inodes_per_block;
4672 			if (end > table)
4673 				end = table;
4674 			while (b <= end)
4675 				sb_breadahead(sb, b++);
4676 		}
4677 
4678 		/*
4679 		 * There are other valid inodes in the buffer, this inode
4680 		 * has in-inode xattrs, or we don't have this inode in memory.
4681 		 * Read the block from disk.
4682 		 */
4683 		trace_ext4_load_inode(inode);
4684 		get_bh(bh);
4685 		bh->b_end_io = end_buffer_read_sync;
4686 		submit_bh(REQ_OP_READ, REQ_META | REQ_PRIO, bh);
4687 		wait_on_buffer(bh);
4688 		if (!buffer_uptodate(bh)) {
4689 			EXT4_ERROR_INODE_BLOCK(inode, block,
4690 					       "unable to read itable block");
4691 			brelse(bh);
4692 			return -EIO;
4693 		}
4694 	}
4695 has_buffer:
4696 	iloc->bh = bh;
4697 	return 0;
4698 }
4699 
4700 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
4701 {
4702 	/* We have all inode data except xattrs in memory here. */
4703 	return __ext4_get_inode_loc(inode, iloc,
4704 		!ext4_test_inode_state(inode, EXT4_STATE_XATTR));
4705 }
4706 
4707 static bool ext4_should_use_dax(struct inode *inode)
4708 {
4709 	if (!test_opt(inode->i_sb, DAX))
4710 		return false;
4711 	if (!S_ISREG(inode->i_mode))
4712 		return false;
4713 	if (ext4_should_journal_data(inode))
4714 		return false;
4715 	if (ext4_has_inline_data(inode))
4716 		return false;
4717 	if (ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT))
4718 		return false;
4719 	return true;
4720 }
4721 
4722 void ext4_set_inode_flags(struct inode *inode)
4723 {
4724 	unsigned int flags = EXT4_I(inode)->i_flags;
4725 	unsigned int new_fl = 0;
4726 
4727 	if (flags & EXT4_SYNC_FL)
4728 		new_fl |= S_SYNC;
4729 	if (flags & EXT4_APPEND_FL)
4730 		new_fl |= S_APPEND;
4731 	if (flags & EXT4_IMMUTABLE_FL)
4732 		new_fl |= S_IMMUTABLE;
4733 	if (flags & EXT4_NOATIME_FL)
4734 		new_fl |= S_NOATIME;
4735 	if (flags & EXT4_DIRSYNC_FL)
4736 		new_fl |= S_DIRSYNC;
4737 	if (ext4_should_use_dax(inode))
4738 		new_fl |= S_DAX;
4739 	if (flags & EXT4_ENCRYPT_FL)
4740 		new_fl |= S_ENCRYPTED;
4741 	inode_set_flags(inode, new_fl,
4742 			S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC|S_DAX|
4743 			S_ENCRYPTED);
4744 }
4745 
4746 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
4747 				  struct ext4_inode_info *ei)
4748 {
4749 	blkcnt_t i_blocks ;
4750 	struct inode *inode = &(ei->vfs_inode);
4751 	struct super_block *sb = inode->i_sb;
4752 
4753 	if (ext4_has_feature_huge_file(sb)) {
4754 		/* we are using combined 48 bit field */
4755 		i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
4756 					le32_to_cpu(raw_inode->i_blocks_lo);
4757 		if (ext4_test_inode_flag(inode, EXT4_INODE_HUGE_FILE)) {
4758 			/* i_blocks represent file system block size */
4759 			return i_blocks  << (inode->i_blkbits - 9);
4760 		} else {
4761 			return i_blocks;
4762 		}
4763 	} else {
4764 		return le32_to_cpu(raw_inode->i_blocks_lo);
4765 	}
4766 }
4767 
4768 static inline int ext4_iget_extra_inode(struct inode *inode,
4769 					 struct ext4_inode *raw_inode,
4770 					 struct ext4_inode_info *ei)
4771 {
4772 	__le32 *magic = (void *)raw_inode +
4773 			EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;
4774 
4775 	if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize + sizeof(__le32) <=
4776 	    EXT4_INODE_SIZE(inode->i_sb) &&
4777 	    *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {
4778 		ext4_set_inode_state(inode, EXT4_STATE_XATTR);
4779 		return ext4_find_inline_data_nolock(inode);
4780 	} else
4781 		EXT4_I(inode)->i_inline_off = 0;
4782 	return 0;
4783 }
4784 
4785 int ext4_get_projid(struct inode *inode, kprojid_t *projid)
4786 {
4787 	if (!ext4_has_feature_project(inode->i_sb))
4788 		return -EOPNOTSUPP;
4789 	*projid = EXT4_I(inode)->i_projid;
4790 	return 0;
4791 }
4792 
4793 /*
4794  * ext4 has self-managed i_version for ea inodes, it stores the lower 32bit of
4795  * refcount in i_version, so use raw values if inode has EXT4_EA_INODE_FL flag
4796  * set.
4797  */
4798 static inline void ext4_inode_set_iversion_queried(struct inode *inode, u64 val)
4799 {
4800 	if (unlikely(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
4801 		inode_set_iversion_raw(inode, val);
4802 	else
4803 		inode_set_iversion_queried(inode, val);
4804 }
4805 static inline u64 ext4_inode_peek_iversion(const struct inode *inode)
4806 {
4807 	if (unlikely(EXT4_I(inode)->i_flags & EXT4_EA_INODE_FL))
4808 		return inode_peek_iversion_raw(inode);
4809 	else
4810 		return inode_peek_iversion(inode);
4811 }
4812 
4813 struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
4814 			  ext4_iget_flags flags, const char *function,
4815 			  unsigned int line)
4816 {
4817 	struct ext4_iloc iloc;
4818 	struct ext4_inode *raw_inode;
4819 	struct ext4_inode_info *ei;
4820 	struct inode *inode;
4821 	journal_t *journal = EXT4_SB(sb)->s_journal;
4822 	long ret;
4823 	loff_t size;
4824 	int block;
4825 	uid_t i_uid;
4826 	gid_t i_gid;
4827 	projid_t i_projid;
4828 
4829 	if ((!(flags & EXT4_IGET_SPECIAL) &&
4830 	     (ino < EXT4_FIRST_INO(sb) && ino != EXT4_ROOT_INO)) ||
4831 	    (ino < EXT4_ROOT_INO) ||
4832 	    (ino > le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count))) {
4833 		if (flags & EXT4_IGET_HANDLE)
4834 			return ERR_PTR(-ESTALE);
4835 		__ext4_error(sb, function, line,
4836 			     "inode #%lu: comm %s: iget: illegal inode #",
4837 			     ino, current->comm);
4838 		return ERR_PTR(-EFSCORRUPTED);
4839 	}
4840 
4841 	inode = iget_locked(sb, ino);
4842 	if (!inode)
4843 		return ERR_PTR(-ENOMEM);
4844 	if (!(inode->i_state & I_NEW))
4845 		return inode;
4846 
4847 	ei = EXT4_I(inode);
4848 	iloc.bh = NULL;
4849 
4850 	ret = __ext4_get_inode_loc(inode, &iloc, 0);
4851 	if (ret < 0)
4852 		goto bad_inode;
4853 	raw_inode = ext4_raw_inode(&iloc);
4854 
4855 	if ((ino == EXT4_ROOT_INO) && (raw_inode->i_links_count == 0)) {
4856 		ext4_error_inode(inode, function, line, 0,
4857 				 "iget: root inode unallocated");
4858 		ret = -EFSCORRUPTED;
4859 		goto bad_inode;
4860 	}
4861 
4862 	if ((flags & EXT4_IGET_HANDLE) &&
4863 	    (raw_inode->i_links_count == 0) && (raw_inode->i_mode == 0)) {
4864 		ret = -ESTALE;
4865 		goto bad_inode;
4866 	}
4867 
4868 	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
4869 		ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
4870 		if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
4871 			EXT4_INODE_SIZE(inode->i_sb) ||
4872 		    (ei->i_extra_isize & 3)) {
4873 			ext4_error_inode(inode, function, line, 0,
4874 					 "iget: bad extra_isize %u "
4875 					 "(inode size %u)",
4876 					 ei->i_extra_isize,
4877 					 EXT4_INODE_SIZE(inode->i_sb));
4878 			ret = -EFSCORRUPTED;
4879 			goto bad_inode;
4880 		}
4881 	} else
4882 		ei->i_extra_isize = 0;
4883 
4884 	/* Precompute checksum seed for inode metadata */
4885 	if (ext4_has_metadata_csum(sb)) {
4886 		struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
4887 		__u32 csum;
4888 		__le32 inum = cpu_to_le32(inode->i_ino);
4889 		__le32 gen = raw_inode->i_generation;
4890 		csum = ext4_chksum(sbi, sbi->s_csum_seed, (__u8 *)&inum,
4891 				   sizeof(inum));
4892 		ei->i_csum_seed = ext4_chksum(sbi, csum, (__u8 *)&gen,
4893 					      sizeof(gen));
4894 	}
4895 
4896 	if (!ext4_inode_csum_verify(inode, raw_inode, ei)) {
4897 		ext4_error_inode(inode, function, line, 0,
4898 				 "iget: checksum invalid");
4899 		ret = -EFSBADCRC;
4900 		goto bad_inode;
4901 	}
4902 
4903 	inode->i_mode = le16_to_cpu(raw_inode->i_mode);
4904 	i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
4905 	i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
4906 	if (ext4_has_feature_project(sb) &&
4907 	    EXT4_INODE_SIZE(sb) > EXT4_GOOD_OLD_INODE_SIZE &&
4908 	    EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
4909 		i_projid = (projid_t)le32_to_cpu(raw_inode->i_projid);
4910 	else
4911 		i_projid = EXT4_DEF_PROJID;
4912 
4913 	if (!(test_opt(inode->i_sb, NO_UID32))) {
4914 		i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
4915 		i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
4916 	}
4917 	i_uid_write(inode, i_uid);
4918 	i_gid_write(inode, i_gid);
4919 	ei->i_projid = make_kprojid(&init_user_ns, i_projid);
4920 	set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
4921 
4922 	ext4_clear_state_flags(ei);	/* Only relevant on 32-bit archs */
4923 	ei->i_inline_off = 0;
4924 	ei->i_dir_start_lookup = 0;
4925 	ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
4926 	/* We now have enough fields to check if the inode was active or not.
4927 	 * This is needed because nfsd might try to access dead inodes
4928 	 * the test is that same one that e2fsck uses
4929 	 * NeilBrown 1999oct15
4930 	 */
4931 	if (inode->i_nlink == 0) {
4932 		if ((inode->i_mode == 0 ||
4933 		     !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) &&
4934 		    ino != EXT4_BOOT_LOADER_INO) {
4935 			/* this inode is deleted */
4936 			ret = -ESTALE;
4937 			goto bad_inode;
4938 		}
4939 		/* The only unlinked inodes we let through here have
4940 		 * valid i_mode and are being read by the orphan
4941 		 * recovery code: that's fine, we're about to complete
4942 		 * the process of deleting those.
4943 		 * OR it is the EXT4_BOOT_LOADER_INO which is
4944 		 * not initialized on a new filesystem. */
4945 	}
4946 	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
4947 	ext4_set_inode_flags(inode);
4948 	inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
4949 	ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
4950 	if (ext4_has_feature_64bit(sb))
4951 		ei->i_file_acl |=
4952 			((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
4953 	inode->i_size = ext4_isize(sb, raw_inode);
4954 	if ((size = i_size_read(inode)) < 0) {
4955 		ext4_error_inode(inode, function, line, 0,
4956 				 "iget: bad i_size value: %lld", size);
4957 		ret = -EFSCORRUPTED;
4958 		goto bad_inode;
4959 	}
4960 	ei->i_disksize = inode->i_size;
4961 #ifdef CONFIG_QUOTA
4962 	ei->i_reserved_quota = 0;
4963 #endif
4964 	inode->i_generation = le32_to_cpu(raw_inode->i_generation);
4965 	ei->i_block_group = iloc.block_group;
4966 	ei->i_last_alloc_group = ~0;
4967 	/*
4968 	 * NOTE! The in-memory inode i_data array is in little-endian order
4969 	 * even on big-endian machines: we do NOT byteswap the block numbers!
4970 	 */
4971 	for (block = 0; block < EXT4_N_BLOCKS; block++)
4972 		ei->i_data[block] = raw_inode->i_block[block];
4973 	INIT_LIST_HEAD(&ei->i_orphan);
4974 
4975 	/*
4976 	 * Set transaction id's of transactions that have to be committed
4977 	 * to finish f[data]sync. We set them to currently running transaction
4978 	 * as we cannot be sure that the inode or some of its metadata isn't
4979 	 * part of the transaction - the inode could have been reclaimed and
4980 	 * now it is reread from disk.
4981 	 */
4982 	if (journal) {
4983 		transaction_t *transaction;
4984 		tid_t tid;
4985 
4986 		read_lock(&journal->j_state_lock);
4987 		if (journal->j_running_transaction)
4988 			transaction = journal->j_running_transaction;
4989 		else
4990 			transaction = journal->j_committing_transaction;
4991 		if (transaction)
4992 			tid = transaction->t_tid;
4993 		else
4994 			tid = journal->j_commit_sequence;
4995 		read_unlock(&journal->j_state_lock);
4996 		ei->i_sync_tid = tid;
4997 		ei->i_datasync_tid = tid;
4998 	}
4999 
5000 	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
5001 		if (ei->i_extra_isize == 0) {
5002 			/* The extra space is currently unused. Use it. */
5003 			BUILD_BUG_ON(sizeof(struct ext4_inode) & 3);
5004 			ei->i_extra_isize = sizeof(struct ext4_inode) -
5005 					    EXT4_GOOD_OLD_INODE_SIZE;
5006 		} else {
5007 			ret = ext4_iget_extra_inode(inode, raw_inode, ei);
5008 			if (ret)
5009 				goto bad_inode;
5010 		}
5011 	}
5012 
5013 	EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
5014 	EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
5015 	EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
5016 	EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
5017 
5018 	if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
5019 		u64 ivers = le32_to_cpu(raw_inode->i_disk_version);
5020 
5021 		if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
5022 			if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
5023 				ivers |=
5024 		    (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
5025 		}
5026 		ext4_inode_set_iversion_queried(inode, ivers);
5027 	}
5028 
5029 	ret = 0;
5030 	if (ei->i_file_acl &&
5031 	    !ext4_data_block_valid(EXT4_SB(sb), ei->i_file_acl, 1)) {
5032 		ext4_error_inode(inode, function, line, 0,
5033 				 "iget: bad extended attribute block %llu",
5034 				 ei->i_file_acl);
5035 		ret = -EFSCORRUPTED;
5036 		goto bad_inode;
5037 	} else if (!ext4_has_inline_data(inode)) {
5038 		/* validate the block references in the inode */
5039 		if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
5040 		   (S_ISLNK(inode->i_mode) &&
5041 		    !ext4_inode_is_fast_symlink(inode))) {
5042 			if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
5043 				ret = ext4_ext_check_inode(inode);
5044 			else
5045 				ret = ext4_ind_check_inode(inode);
5046 		}
5047 	}
5048 	if (ret)
5049 		goto bad_inode;
5050 
5051 	if (S_ISREG(inode->i_mode)) {
5052 		inode->i_op = &ext4_file_inode_operations;
5053 		inode->i_fop = &ext4_file_operations;
5054 		ext4_set_aops(inode);
5055 	} else if (S_ISDIR(inode->i_mode)) {
5056 		inode->i_op = &ext4_dir_inode_operations;
5057 		inode->i_fop = &ext4_dir_operations;
5058 	} else if (S_ISLNK(inode->i_mode)) {
5059 		/* VFS does not allow setting these so must be corruption */
5060 		if (IS_APPEND(inode) || IS_IMMUTABLE(inode)) {
5061 			ext4_error_inode(inode, function, line, 0,
5062 					 "iget: immutable or append flags "
5063 					 "not allowed on symlinks");
5064 			ret = -EFSCORRUPTED;
5065 			goto bad_inode;
5066 		}
5067 		if (IS_ENCRYPTED(inode)) {
5068 			inode->i_op = &ext4_encrypted_symlink_inode_operations;
5069 			ext4_set_aops(inode);
5070 		} else if (ext4_inode_is_fast_symlink(inode)) {
5071 			inode->i_link = (char *)ei->i_data;
5072 			inode->i_op = &ext4_fast_symlink_inode_operations;
5073 			nd_terminate_link(ei->i_data, inode->i_size,
5074 				sizeof(ei->i_data) - 1);
5075 		} else {
5076 			inode->i_op = &ext4_symlink_inode_operations;
5077 			ext4_set_aops(inode);
5078 		}
5079 		inode_nohighmem(inode);
5080 	} else if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode) ||
5081 	      S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
5082 		inode->i_op = &ext4_special_inode_operations;
5083 		if (raw_inode->i_block[0])
5084 			init_special_inode(inode, inode->i_mode,
5085 			   old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
5086 		else
5087 			init_special_inode(inode, inode->i_mode,
5088 			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
5089 	} else if (ino == EXT4_BOOT_LOADER_INO) {
5090 		make_bad_inode(inode);
5091 	} else {
5092 		ret = -EFSCORRUPTED;
5093 		ext4_error_inode(inode, function, line, 0,
5094 				 "iget: bogus i_mode (%o)", inode->i_mode);
5095 		goto bad_inode;
5096 	}
5097 	brelse(iloc.bh);
5098 
5099 	unlock_new_inode(inode);
5100 	return inode;
5101 
5102 bad_inode:
5103 	brelse(iloc.bh);
5104 	iget_failed(inode);
5105 	return ERR_PTR(ret);
5106 }
5107 
5108 static int ext4_inode_blocks_set(handle_t *handle,
5109 				struct ext4_inode *raw_inode,
5110 				struct ext4_inode_info *ei)
5111 {
5112 	struct inode *inode = &(ei->vfs_inode);
5113 	u64 i_blocks = inode->i_blocks;
5114 	struct super_block *sb = inode->i_sb;
5115 
5116 	if (i_blocks <= ~0U) {
5117 		/*
5118 		 * i_blocks can be represented in a 32 bit variable
5119 		 * as multiple of 512 bytes
5120 		 */
5121 		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
5122 		raw_inode->i_blocks_high = 0;
5123 		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
5124 		return 0;
5125 	}
5126 	if (!ext4_has_feature_huge_file(sb))
5127 		return -EFBIG;
5128 
5129 	if (i_blocks <= 0xffffffffffffULL) {
5130 		/*
5131 		 * i_blocks can be represented in a 48 bit variable
5132 		 * as multiple of 512 bytes
5133 		 */
5134 		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
5135 		raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
5136 		ext4_clear_inode_flag(inode, EXT4_INODE_HUGE_FILE);
5137 	} else {
5138 		ext4_set_inode_flag(inode, EXT4_INODE_HUGE_FILE);
5139 		/* i_block is stored in file system block size */
5140 		i_blocks = i_blocks >> (inode->i_blkbits - 9);
5141 		raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
5142 		raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
5143 	}
5144 	return 0;
5145 }
5146 
5147 struct other_inode {
5148 	unsigned long		orig_ino;
5149 	struct ext4_inode	*raw_inode;
5150 };
5151 
5152 static int other_inode_match(struct inode * inode, unsigned long ino,
5153 			     void *data)
5154 {
5155 	struct other_inode *oi = (struct other_inode *) data;
5156 
5157 	if ((inode->i_ino != ino) ||
5158 	    (inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
5159 			       I_DIRTY_INODE)) ||
5160 	    ((inode->i_state & I_DIRTY_TIME) == 0))
5161 		return 0;
5162 	spin_lock(&inode->i_lock);
5163 	if (((inode->i_state & (I_FREEING | I_WILL_FREE | I_NEW |
5164 				I_DIRTY_INODE)) == 0) &&
5165 	    (inode->i_state & I_DIRTY_TIME)) {
5166 		struct ext4_inode_info	*ei = EXT4_I(inode);
5167 
5168 		inode->i_state &= ~(I_DIRTY_TIME | I_DIRTY_TIME_EXPIRED);
5169 		spin_unlock(&inode->i_lock);
5170 
5171 		spin_lock(&ei->i_raw_lock);
5172 		EXT4_INODE_SET_XTIME(i_ctime, inode, oi->raw_inode);
5173 		EXT4_INODE_SET_XTIME(i_mtime, inode, oi->raw_inode);
5174 		EXT4_INODE_SET_XTIME(i_atime, inode, oi->raw_inode);
5175 		ext4_inode_csum_set(inode, oi->raw_inode, ei);
5176 		spin_unlock(&ei->i_raw_lock);
5177 		trace_ext4_other_inode_update_time(inode, oi->orig_ino);
5178 		return -1;
5179 	}
5180 	spin_unlock(&inode->i_lock);
5181 	return -1;
5182 }
5183 
5184 /*
5185  * Opportunistically update the other time fields for other inodes in
5186  * the same inode table block.
5187  */
5188 static void ext4_update_other_inodes_time(struct super_block *sb,
5189 					  unsigned long orig_ino, char *buf)
5190 {
5191 	struct other_inode oi;
5192 	unsigned long ino;
5193 	int i, inodes_per_block = EXT4_SB(sb)->s_inodes_per_block;
5194 	int inode_size = EXT4_INODE_SIZE(sb);
5195 
5196 	oi.orig_ino = orig_ino;
5197 	/*
5198 	 * Calculate the first inode in the inode table block.  Inode
5199 	 * numbers are one-based.  That is, the first inode in a block
5200 	 * (assuming 4k blocks and 256 byte inodes) is (n*16 + 1).
5201 	 */
5202 	ino = ((orig_ino - 1) & ~(inodes_per_block - 1)) + 1;
5203 	for (i = 0; i < inodes_per_block; i++, ino++, buf += inode_size) {
5204 		if (ino == orig_ino)
5205 			continue;
5206 		oi.raw_inode = (struct ext4_inode *) buf;
5207 		(void) find_inode_nowait(sb, ino, other_inode_match, &oi);
5208 	}
5209 }
5210 
5211 /*
5212  * Post the struct inode info into an on-disk inode location in the
5213  * buffer-cache.  This gobbles the caller's reference to the
5214  * buffer_head in the inode location struct.
5215  *
5216  * The caller must have write access to iloc->bh.
5217  */
5218 static int ext4_do_update_inode(handle_t *handle,
5219 				struct inode *inode,
5220 				struct ext4_iloc *iloc)
5221 {
5222 	struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
5223 	struct ext4_inode_info *ei = EXT4_I(inode);
5224 	struct buffer_head *bh = iloc->bh;
5225 	struct super_block *sb = inode->i_sb;
5226 	int err = 0, rc, block;
5227 	int need_datasync = 0, set_large_file = 0;
5228 	uid_t i_uid;
5229 	gid_t i_gid;
5230 	projid_t i_projid;
5231 
5232 	spin_lock(&ei->i_raw_lock);
5233 
5234 	/* For fields not tracked in the in-memory inode,
5235 	 * initialise them to zero for new inodes. */
5236 	if (ext4_test_inode_state(inode, EXT4_STATE_NEW))
5237 		memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
5238 
5239 	raw_inode->i_mode = cpu_to_le16(inode->i_mode);
5240 	i_uid = i_uid_read(inode);
5241 	i_gid = i_gid_read(inode);
5242 	i_projid = from_kprojid(&init_user_ns, ei->i_projid);
5243 	if (!(test_opt(inode->i_sb, NO_UID32))) {
5244 		raw_inode->i_uid_low = cpu_to_le16(low_16_bits(i_uid));
5245 		raw_inode->i_gid_low = cpu_to_le16(low_16_bits(i_gid));
5246 /*
5247  * Fix up interoperability with old kernels. Otherwise, old inodes get
5248  * re-used with the upper 16 bits of the uid/gid intact
5249  */
5250 		if (ei->i_dtime && list_empty(&ei->i_orphan)) {
5251 			raw_inode->i_uid_high = 0;
5252 			raw_inode->i_gid_high = 0;
5253 		} else {
5254 			raw_inode->i_uid_high =
5255 				cpu_to_le16(high_16_bits(i_uid));
5256 			raw_inode->i_gid_high =
5257 				cpu_to_le16(high_16_bits(i_gid));
5258 		}
5259 	} else {
5260 		raw_inode->i_uid_low = cpu_to_le16(fs_high2lowuid(i_uid));
5261 		raw_inode->i_gid_low = cpu_to_le16(fs_high2lowgid(i_gid));
5262 		raw_inode->i_uid_high = 0;
5263 		raw_inode->i_gid_high = 0;
5264 	}
5265 	raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
5266 
5267 	EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
5268 	EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
5269 	EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
5270 	EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
5271 
5272 	err = ext4_inode_blocks_set(handle, raw_inode, ei);
5273 	if (err) {
5274 		spin_unlock(&ei->i_raw_lock);
5275 		goto out_brelse;
5276 	}
5277 	raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
5278 	raw_inode->i_flags = cpu_to_le32(ei->i_flags & 0xFFFFFFFF);
5279 	if (likely(!test_opt2(inode->i_sb, HURD_COMPAT)))
5280 		raw_inode->i_file_acl_high =
5281 			cpu_to_le16(ei->i_file_acl >> 32);
5282 	raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
5283 	if (ei->i_disksize != ext4_isize(inode->i_sb, raw_inode)) {
5284 		ext4_isize_set(raw_inode, ei->i_disksize);
5285 		need_datasync = 1;
5286 	}
5287 	if (ei->i_disksize > 0x7fffffffULL) {
5288 		if (!ext4_has_feature_large_file(sb) ||
5289 				EXT4_SB(sb)->s_es->s_rev_level ==
5290 		    cpu_to_le32(EXT4_GOOD_OLD_REV))
5291 			set_large_file = 1;
5292 	}
5293 	raw_inode->i_generation = cpu_to_le32(inode->i_generation);
5294 	if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
5295 		if (old_valid_dev(inode->i_rdev)) {
5296 			raw_inode->i_block[0] =
5297 				cpu_to_le32(old_encode_dev(inode->i_rdev));
5298 			raw_inode->i_block[1] = 0;
5299 		} else {
5300 			raw_inode->i_block[0] = 0;
5301 			raw_inode->i_block[1] =
5302 				cpu_to_le32(new_encode_dev(inode->i_rdev));
5303 			raw_inode->i_block[2] = 0;
5304 		}
5305 	} else if (!ext4_has_inline_data(inode)) {
5306 		for (block = 0; block < EXT4_N_BLOCKS; block++)
5307 			raw_inode->i_block[block] = ei->i_data[block];
5308 	}
5309 
5310 	if (likely(!test_opt2(inode->i_sb, HURD_COMPAT))) {
5311 		u64 ivers = ext4_inode_peek_iversion(inode);
5312 
5313 		raw_inode->i_disk_version = cpu_to_le32(ivers);
5314 		if (ei->i_extra_isize) {
5315 			if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
5316 				raw_inode->i_version_hi =
5317 					cpu_to_le32(ivers >> 32);
5318 			raw_inode->i_extra_isize =
5319 				cpu_to_le16(ei->i_extra_isize);
5320 		}
5321 	}
5322 
5323 	BUG_ON(!ext4_has_feature_project(inode->i_sb) &&
5324 	       i_projid != EXT4_DEF_PROJID);
5325 
5326 	if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE &&
5327 	    EXT4_FITS_IN_INODE(raw_inode, ei, i_projid))
5328 		raw_inode->i_projid = cpu_to_le32(i_projid);
5329 
5330 	ext4_inode_csum_set(inode, raw_inode, ei);
5331 	spin_unlock(&ei->i_raw_lock);
5332 	if (inode->i_sb->s_flags & SB_LAZYTIME)
5333 		ext4_update_other_inodes_time(inode->i_sb, inode->i_ino,
5334 					      bh->b_data);
5335 
5336 	BUFFER_TRACE(bh, "call ext4_handle_dirty_metadata");
5337 	rc = ext4_handle_dirty_metadata(handle, NULL, bh);
5338 	if (!err)
5339 		err = rc;
5340 	ext4_clear_inode_state(inode, EXT4_STATE_NEW);
5341 	if (set_large_file) {
5342 		BUFFER_TRACE(EXT4_SB(sb)->s_sbh, "get write access");
5343 		err = ext4_journal_get_write_access(handle, EXT4_SB(sb)->s_sbh);
5344 		if (err)
5345 			goto out_brelse;
5346 		ext4_set_feature_large_file(sb);
5347 		ext4_handle_sync(handle);
5348 		err = ext4_handle_dirty_super(handle, sb);
5349 	}
5350 	ext4_update_inode_fsync_trans(handle, inode, need_datasync);
5351 out_brelse:
5352 	brelse(bh);
5353 	ext4_std_error(inode->i_sb, err);
5354 	return err;
5355 }
5356 
5357 /*
5358  * ext4_write_inode()
5359  *
5360  * We are called from a few places:
5361  *
5362  * - Within generic_file_aio_write() -> generic_write_sync() for O_SYNC files.
5363  *   Here, there will be no transaction running. We wait for any running
5364  *   transaction to commit.
5365  *
5366  * - Within flush work (sys_sync(), kupdate and such).
5367  *   We wait on commit, if told to.
5368  *
5369  * - Within iput_final() -> write_inode_now()
5370  *   We wait on commit, if told to.
5371  *
5372  * In all cases it is actually safe for us to return without doing anything,
5373  * because the inode has been copied into a raw inode buffer in
5374  * ext4_mark_inode_dirty().  This is a correctness thing for WB_SYNC_ALL
5375  * writeback.
5376  *
5377  * Note that we are absolutely dependent upon all inode dirtiers doing the
5378  * right thing: they *must* call mark_inode_dirty() after dirtying info in
5379  * which we are interested.
5380  *
5381  * It would be a bug for them to not do this.  The code:
5382  *
5383  *	mark_inode_dirty(inode)
5384  *	stuff();
5385  *	inode->i_size = expr;
5386  *
5387  * is in error because write_inode() could occur while `stuff()' is running,
5388  * and the new i_size will be lost.  Plus the inode will no longer be on the
5389  * superblock's dirty inode list.
5390  */
5391 int ext4_write_inode(struct inode *inode, struct writeback_control *wbc)
5392 {
5393 	int err;
5394 
5395 	if (WARN_ON_ONCE(current->flags & PF_MEMALLOC) ||
5396 	    sb_rdonly(inode->i_sb))
5397 		return 0;
5398 
5399 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
5400 		return -EIO;
5401 
5402 	if (EXT4_SB(inode->i_sb)->s_journal) {
5403 		if (ext4_journal_current_handle()) {
5404 			jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
5405 			dump_stack();
5406 			return -EIO;
5407 		}
5408 
5409 		/*
5410 		 * No need to force transaction in WB_SYNC_NONE mode. Also
5411 		 * ext4_sync_fs() will force the commit after everything is
5412 		 * written.
5413 		 */
5414 		if (wbc->sync_mode != WB_SYNC_ALL || wbc->for_sync)
5415 			return 0;
5416 
5417 		err = jbd2_complete_transaction(EXT4_SB(inode->i_sb)->s_journal,
5418 						EXT4_I(inode)->i_sync_tid);
5419 	} else {
5420 		struct ext4_iloc iloc;
5421 
5422 		err = __ext4_get_inode_loc(inode, &iloc, 0);
5423 		if (err)
5424 			return err;
5425 		/*
5426 		 * sync(2) will flush the whole buffer cache. No need to do
5427 		 * it here separately for each inode.
5428 		 */
5429 		if (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync)
5430 			sync_dirty_buffer(iloc.bh);
5431 		if (buffer_req(iloc.bh) && !buffer_uptodate(iloc.bh)) {
5432 			EXT4_ERROR_INODE_BLOCK(inode, iloc.bh->b_blocknr,
5433 					 "IO error syncing inode");
5434 			err = -EIO;
5435 		}
5436 		brelse(iloc.bh);
5437 	}
5438 	return err;
5439 }
5440 
5441 /*
5442  * In data=journal mode ext4_journalled_invalidatepage() may fail to invalidate
5443  * buffers that are attached to a page stradding i_size and are undergoing
5444  * commit. In that case we have to wait for commit to finish and try again.
5445  */
5446 static void ext4_wait_for_tail_page_commit(struct inode *inode)
5447 {
5448 	struct page *page;
5449 	unsigned offset;
5450 	journal_t *journal = EXT4_SB(inode->i_sb)->s_journal;
5451 	tid_t commit_tid = 0;
5452 	int ret;
5453 
5454 	offset = inode->i_size & (PAGE_SIZE - 1);
5455 	/*
5456 	 * All buffers in the last page remain valid? Then there's nothing to
5457 	 * do. We do the check mainly to optimize the common PAGE_SIZE ==
5458 	 * blocksize case
5459 	 */
5460 	if (offset > PAGE_SIZE - i_blocksize(inode))
5461 		return;
5462 	while (1) {
5463 		page = find_lock_page(inode->i_mapping,
5464 				      inode->i_size >> PAGE_SHIFT);
5465 		if (!page)
5466 			return;
5467 		ret = __ext4_journalled_invalidatepage(page, offset,
5468 						PAGE_SIZE - offset);
5469 		unlock_page(page);
5470 		put_page(page);
5471 		if (ret != -EBUSY)
5472 			return;
5473 		commit_tid = 0;
5474 		read_lock(&journal->j_state_lock);
5475 		if (journal->j_committing_transaction)
5476 			commit_tid = journal->j_committing_transaction->t_tid;
5477 		read_unlock(&journal->j_state_lock);
5478 		if (commit_tid)
5479 			jbd2_log_wait_commit(journal, commit_tid);
5480 	}
5481 }
5482 
5483 /*
5484  * ext4_setattr()
5485  *
5486  * Called from notify_change.
5487  *
5488  * We want to trap VFS attempts to truncate the file as soon as
5489  * possible.  In particular, we want to make sure that when the VFS
5490  * shrinks i_size, we put the inode on the orphan list and modify
5491  * i_disksize immediately, so that during the subsequent flushing of
5492  * dirty pages and freeing of disk blocks, we can guarantee that any
5493  * commit will leave the blocks being flushed in an unused state on
5494  * disk.  (On recovery, the inode will get truncated and the blocks will
5495  * be freed, so we have a strong guarantee that no future commit will
5496  * leave these blocks visible to the user.)
5497  *
5498  * Another thing we have to assure is that if we are in ordered mode
5499  * and inode is still attached to the committing transaction, we must
5500  * we start writeout of all the dirty pages which are being truncated.
5501  * This way we are sure that all the data written in the previous
5502  * transaction are already on disk (truncate waits for pages under
5503  * writeback).
5504  *
5505  * Called with inode->i_mutex down.
5506  */
5507 int ext4_setattr(struct dentry *dentry, struct iattr *attr)
5508 {
5509 	struct inode *inode = d_inode(dentry);
5510 	int error, rc = 0;
5511 	int orphan = 0;
5512 	const unsigned int ia_valid = attr->ia_valid;
5513 
5514 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
5515 		return -EIO;
5516 
5517 	error = setattr_prepare(dentry, attr);
5518 	if (error)
5519 		return error;
5520 
5521 	error = fscrypt_prepare_setattr(dentry, attr);
5522 	if (error)
5523 		return error;
5524 
5525 	if (is_quota_modification(inode, attr)) {
5526 		error = dquot_initialize(inode);
5527 		if (error)
5528 			return error;
5529 	}
5530 	if ((ia_valid & ATTR_UID && !uid_eq(attr->ia_uid, inode->i_uid)) ||
5531 	    (ia_valid & ATTR_GID && !gid_eq(attr->ia_gid, inode->i_gid))) {
5532 		handle_t *handle;
5533 
5534 		/* (user+group)*(old+new) structure, inode write (sb,
5535 		 * inode block, ? - but truncate inode update has it) */
5536 		handle = ext4_journal_start(inode, EXT4_HT_QUOTA,
5537 			(EXT4_MAXQUOTAS_INIT_BLOCKS(inode->i_sb) +
5538 			 EXT4_MAXQUOTAS_DEL_BLOCKS(inode->i_sb)) + 3);
5539 		if (IS_ERR(handle)) {
5540 			error = PTR_ERR(handle);
5541 			goto err_out;
5542 		}
5543 
5544 		/* dquot_transfer() calls back ext4_get_inode_usage() which
5545 		 * counts xattr inode references.
5546 		 */
5547 		down_read(&EXT4_I(inode)->xattr_sem);
5548 		error = dquot_transfer(inode, attr);
5549 		up_read(&EXT4_I(inode)->xattr_sem);
5550 
5551 		if (error) {
5552 			ext4_journal_stop(handle);
5553 			return error;
5554 		}
5555 		/* Update corresponding info in inode so that everything is in
5556 		 * one transaction */
5557 		if (attr->ia_valid & ATTR_UID)
5558 			inode->i_uid = attr->ia_uid;
5559 		if (attr->ia_valid & ATTR_GID)
5560 			inode->i_gid = attr->ia_gid;
5561 		error = ext4_mark_inode_dirty(handle, inode);
5562 		ext4_journal_stop(handle);
5563 	}
5564 
5565 	if (attr->ia_valid & ATTR_SIZE) {
5566 		handle_t *handle;
5567 		loff_t oldsize = inode->i_size;
5568 		int shrink = (attr->ia_size <= inode->i_size);
5569 
5570 		if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
5571 			struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
5572 
5573 			if (attr->ia_size > sbi->s_bitmap_maxbytes)
5574 				return -EFBIG;
5575 		}
5576 		if (!S_ISREG(inode->i_mode))
5577 			return -EINVAL;
5578 
5579 		if (IS_I_VERSION(inode) && attr->ia_size != inode->i_size)
5580 			inode_inc_iversion(inode);
5581 
5582 		if (ext4_should_order_data(inode) &&
5583 		    (attr->ia_size < inode->i_size)) {
5584 			error = ext4_begin_ordered_truncate(inode,
5585 							    attr->ia_size);
5586 			if (error)
5587 				goto err_out;
5588 		}
5589 		if (attr->ia_size != inode->i_size) {
5590 			handle = ext4_journal_start(inode, EXT4_HT_INODE, 3);
5591 			if (IS_ERR(handle)) {
5592 				error = PTR_ERR(handle);
5593 				goto err_out;
5594 			}
5595 			if (ext4_handle_valid(handle) && shrink) {
5596 				error = ext4_orphan_add(handle, inode);
5597 				orphan = 1;
5598 			}
5599 			/*
5600 			 * Update c/mtime on truncate up, ext4_truncate() will
5601 			 * update c/mtime in shrink case below
5602 			 */
5603 			if (!shrink) {
5604 				inode->i_mtime = current_time(inode);
5605 				inode->i_ctime = inode->i_mtime;
5606 			}
5607 			down_write(&EXT4_I(inode)->i_data_sem);
5608 			EXT4_I(inode)->i_disksize = attr->ia_size;
5609 			rc = ext4_mark_inode_dirty(handle, inode);
5610 			if (!error)
5611 				error = rc;
5612 			/*
5613 			 * We have to update i_size under i_data_sem together
5614 			 * with i_disksize to avoid races with writeback code
5615 			 * running ext4_wb_update_i_disksize().
5616 			 */
5617 			if (!error)
5618 				i_size_write(inode, attr->ia_size);
5619 			up_write(&EXT4_I(inode)->i_data_sem);
5620 			ext4_journal_stop(handle);
5621 			if (error) {
5622 				if (orphan)
5623 					ext4_orphan_del(NULL, inode);
5624 				goto err_out;
5625 			}
5626 		}
5627 		if (!shrink)
5628 			pagecache_isize_extended(inode, oldsize, inode->i_size);
5629 
5630 		/*
5631 		 * Blocks are going to be removed from the inode. Wait
5632 		 * for dio in flight.  Temporarily disable
5633 		 * dioread_nolock to prevent livelock.
5634 		 */
5635 		if (orphan) {
5636 			if (!ext4_should_journal_data(inode)) {
5637 				inode_dio_wait(inode);
5638 			} else
5639 				ext4_wait_for_tail_page_commit(inode);
5640 		}
5641 		down_write(&EXT4_I(inode)->i_mmap_sem);
5642 
5643 		rc = ext4_break_layouts(inode);
5644 		if (rc) {
5645 			up_write(&EXT4_I(inode)->i_mmap_sem);
5646 			error = rc;
5647 			goto err_out;
5648 		}
5649 
5650 		/*
5651 		 * Truncate pagecache after we've waited for commit
5652 		 * in data=journal mode to make pages freeable.
5653 		 */
5654 		truncate_pagecache(inode, inode->i_size);
5655 		if (shrink) {
5656 			rc = ext4_truncate(inode);
5657 			if (rc)
5658 				error = rc;
5659 		}
5660 		up_write(&EXT4_I(inode)->i_mmap_sem);
5661 	}
5662 
5663 	if (!error) {
5664 		setattr_copy(inode, attr);
5665 		mark_inode_dirty(inode);
5666 	}
5667 
5668 	/*
5669 	 * If the call to ext4_truncate failed to get a transaction handle at
5670 	 * all, we need to clean up the in-core orphan list manually.
5671 	 */
5672 	if (orphan && inode->i_nlink)
5673 		ext4_orphan_del(NULL, inode);
5674 
5675 	if (!error && (ia_valid & ATTR_MODE))
5676 		rc = posix_acl_chmod(inode, inode->i_mode);
5677 
5678 err_out:
5679 	ext4_std_error(inode->i_sb, error);
5680 	if (!error)
5681 		error = rc;
5682 	return error;
5683 }
5684 
5685 int ext4_getattr(const struct path *path, struct kstat *stat,
5686 		 u32 request_mask, unsigned int query_flags)
5687 {
5688 	struct inode *inode = d_inode(path->dentry);
5689 	struct ext4_inode *raw_inode;
5690 	struct ext4_inode_info *ei = EXT4_I(inode);
5691 	unsigned int flags;
5692 
5693 	if (EXT4_FITS_IN_INODE(raw_inode, ei, i_crtime)) {
5694 		stat->result_mask |= STATX_BTIME;
5695 		stat->btime.tv_sec = ei->i_crtime.tv_sec;
5696 		stat->btime.tv_nsec = ei->i_crtime.tv_nsec;
5697 	}
5698 
5699 	flags = ei->i_flags & EXT4_FL_USER_VISIBLE;
5700 	if (flags & EXT4_APPEND_FL)
5701 		stat->attributes |= STATX_ATTR_APPEND;
5702 	if (flags & EXT4_COMPR_FL)
5703 		stat->attributes |= STATX_ATTR_COMPRESSED;
5704 	if (flags & EXT4_ENCRYPT_FL)
5705 		stat->attributes |= STATX_ATTR_ENCRYPTED;
5706 	if (flags & EXT4_IMMUTABLE_FL)
5707 		stat->attributes |= STATX_ATTR_IMMUTABLE;
5708 	if (flags & EXT4_NODUMP_FL)
5709 		stat->attributes |= STATX_ATTR_NODUMP;
5710 
5711 	stat->attributes_mask |= (STATX_ATTR_APPEND |
5712 				  STATX_ATTR_COMPRESSED |
5713 				  STATX_ATTR_ENCRYPTED |
5714 				  STATX_ATTR_IMMUTABLE |
5715 				  STATX_ATTR_NODUMP);
5716 
5717 	generic_fillattr(inode, stat);
5718 	return 0;
5719 }
5720 
5721 int ext4_file_getattr(const struct path *path, struct kstat *stat,
5722 		      u32 request_mask, unsigned int query_flags)
5723 {
5724 	struct inode *inode = d_inode(path->dentry);
5725 	u64 delalloc_blocks;
5726 
5727 	ext4_getattr(path, stat, request_mask, query_flags);
5728 
5729 	/*
5730 	 * If there is inline data in the inode, the inode will normally not
5731 	 * have data blocks allocated (it may have an external xattr block).
5732 	 * Report at least one sector for such files, so tools like tar, rsync,
5733 	 * others don't incorrectly think the file is completely sparse.
5734 	 */
5735 	if (unlikely(ext4_has_inline_data(inode)))
5736 		stat->blocks += (stat->size + 511) >> 9;
5737 
5738 	/*
5739 	 * We can't update i_blocks if the block allocation is delayed
5740 	 * otherwise in the case of system crash before the real block
5741 	 * allocation is done, we will have i_blocks inconsistent with
5742 	 * on-disk file blocks.
5743 	 * We always keep i_blocks updated together with real
5744 	 * allocation. But to not confuse with user, stat
5745 	 * will return the blocks that include the delayed allocation
5746 	 * blocks for this file.
5747 	 */
5748 	delalloc_blocks = EXT4_C2B(EXT4_SB(inode->i_sb),
5749 				   EXT4_I(inode)->i_reserved_data_blocks);
5750 	stat->blocks += delalloc_blocks << (inode->i_sb->s_blocksize_bits - 9);
5751 	return 0;
5752 }
5753 
5754 static int ext4_index_trans_blocks(struct inode *inode, int lblocks,
5755 				   int pextents)
5756 {
5757 	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
5758 		return ext4_ind_trans_blocks(inode, lblocks);
5759 	return ext4_ext_index_trans_blocks(inode, pextents);
5760 }
5761 
5762 /*
5763  * Account for index blocks, block groups bitmaps and block group
5764  * descriptor blocks if modify datablocks and index blocks
5765  * worse case, the indexs blocks spread over different block groups
5766  *
5767  * If datablocks are discontiguous, they are possible to spread over
5768  * different block groups too. If they are contiguous, with flexbg,
5769  * they could still across block group boundary.
5770  *
5771  * Also account for superblock, inode, quota and xattr blocks
5772  */
5773 static int ext4_meta_trans_blocks(struct inode *inode, int lblocks,
5774 				  int pextents)
5775 {
5776 	ext4_group_t groups, ngroups = ext4_get_groups_count(inode->i_sb);
5777 	int gdpblocks;
5778 	int idxblocks;
5779 	int ret = 0;
5780 
5781 	/*
5782 	 * How many index blocks need to touch to map @lblocks logical blocks
5783 	 * to @pextents physical extents?
5784 	 */
5785 	idxblocks = ext4_index_trans_blocks(inode, lblocks, pextents);
5786 
5787 	ret = idxblocks;
5788 
5789 	/*
5790 	 * Now let's see how many group bitmaps and group descriptors need
5791 	 * to account
5792 	 */
5793 	groups = idxblocks + pextents;
5794 	gdpblocks = groups;
5795 	if (groups > ngroups)
5796 		groups = ngroups;
5797 	if (groups > EXT4_SB(inode->i_sb)->s_gdb_count)
5798 		gdpblocks = EXT4_SB(inode->i_sb)->s_gdb_count;
5799 
5800 	/* bitmaps and block group descriptor blocks */
5801 	ret += groups + gdpblocks;
5802 
5803 	/* Blocks for super block, inode, quota and xattr blocks */
5804 	ret += EXT4_META_TRANS_BLOCKS(inode->i_sb);
5805 
5806 	return ret;
5807 }
5808 
5809 /*
5810  * Calculate the total number of credits to reserve to fit
5811  * the modification of a single pages into a single transaction,
5812  * which may include multiple chunks of block allocations.
5813  *
5814  * This could be called via ext4_write_begin()
5815  *
5816  * We need to consider the worse case, when
5817  * one new block per extent.
5818  */
5819 int ext4_writepage_trans_blocks(struct inode *inode)
5820 {
5821 	int bpp = ext4_journal_blocks_per_page(inode);
5822 	int ret;
5823 
5824 	ret = ext4_meta_trans_blocks(inode, bpp, bpp);
5825 
5826 	/* Account for data blocks for journalled mode */
5827 	if (ext4_should_journal_data(inode))
5828 		ret += bpp;
5829 	return ret;
5830 }
5831 
5832 /*
5833  * Calculate the journal credits for a chunk of data modification.
5834  *
5835  * This is called from DIO, fallocate or whoever calling
5836  * ext4_map_blocks() to map/allocate a chunk of contiguous disk blocks.
5837  *
5838  * journal buffers for data blocks are not included here, as DIO
5839  * and fallocate do no need to journal data buffers.
5840  */
5841 int ext4_chunk_trans_blocks(struct inode *inode, int nrblocks)
5842 {
5843 	return ext4_meta_trans_blocks(inode, nrblocks, 1);
5844 }
5845 
5846 /*
5847  * The caller must have previously called ext4_reserve_inode_write().
5848  * Give this, we know that the caller already has write access to iloc->bh.
5849  */
5850 int ext4_mark_iloc_dirty(handle_t *handle,
5851 			 struct inode *inode, struct ext4_iloc *iloc)
5852 {
5853 	int err = 0;
5854 
5855 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb)))) {
5856 		put_bh(iloc->bh);
5857 		return -EIO;
5858 	}
5859 	if (IS_I_VERSION(inode))
5860 		inode_inc_iversion(inode);
5861 
5862 	/* the do_update_inode consumes one bh->b_count */
5863 	get_bh(iloc->bh);
5864 
5865 	/* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
5866 	err = ext4_do_update_inode(handle, inode, iloc);
5867 	put_bh(iloc->bh);
5868 	return err;
5869 }
5870 
5871 /*
5872  * On success, We end up with an outstanding reference count against
5873  * iloc->bh.  This _must_ be cleaned up later.
5874  */
5875 
5876 int
5877 ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
5878 			 struct ext4_iloc *iloc)
5879 {
5880 	int err;
5881 
5882 	if (unlikely(ext4_forced_shutdown(EXT4_SB(inode->i_sb))))
5883 		return -EIO;
5884 
5885 	err = ext4_get_inode_loc(inode, iloc);
5886 	if (!err) {
5887 		BUFFER_TRACE(iloc->bh, "get_write_access");
5888 		err = ext4_journal_get_write_access(handle, iloc->bh);
5889 		if (err) {
5890 			brelse(iloc->bh);
5891 			iloc->bh = NULL;
5892 		}
5893 	}
5894 	ext4_std_error(inode->i_sb, err);
5895 	return err;
5896 }
5897 
5898 static int __ext4_expand_extra_isize(struct inode *inode,
5899 				     unsigned int new_extra_isize,
5900 				     struct ext4_iloc *iloc,
5901 				     handle_t *handle, int *no_expand)
5902 {
5903 	struct ext4_inode *raw_inode;
5904 	struct ext4_xattr_ibody_header *header;
5905 	int error;
5906 
5907 	raw_inode = ext4_raw_inode(iloc);
5908 
5909 	header = IHDR(inode, raw_inode);
5910 
5911 	/* No extended attributes present */
5912 	if (!ext4_test_inode_state(inode, EXT4_STATE_XATTR) ||
5913 	    header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
5914 		memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE +
5915 		       EXT4_I(inode)->i_extra_isize, 0,
5916 		       new_extra_isize - EXT4_I(inode)->i_extra_isize);
5917 		EXT4_I(inode)->i_extra_isize = new_extra_isize;
5918 		return 0;
5919 	}
5920 
5921 	/* try to expand with EAs present */
5922 	error = ext4_expand_extra_isize_ea(inode, new_extra_isize,
5923 					   raw_inode, handle);
5924 	if (error) {
5925 		/*
5926 		 * Inode size expansion failed; don't try again
5927 		 */
5928 		*no_expand = 1;
5929 	}
5930 
5931 	return error;
5932 }
5933 
5934 /*
5935  * Expand an inode by new_extra_isize bytes.
5936  * Returns 0 on success or negative error number on failure.
5937  */
5938 static int ext4_try_to_expand_extra_isize(struct inode *inode,
5939 					  unsigned int new_extra_isize,
5940 					  struct ext4_iloc iloc,
5941 					  handle_t *handle)
5942 {
5943 	int no_expand;
5944 	int error;
5945 
5946 	if (ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND))
5947 		return -EOVERFLOW;
5948 
5949 	/*
5950 	 * In nojournal mode, we can immediately attempt to expand
5951 	 * the inode.  When journaled, we first need to obtain extra
5952 	 * buffer credits since we may write into the EA block
5953 	 * with this same handle. If journal_extend fails, then it will
5954 	 * only result in a minor loss of functionality for that inode.
5955 	 * If this is felt to be critical, then e2fsck should be run to
5956 	 * force a large enough s_min_extra_isize.
5957 	 */
5958 	if (ext4_handle_valid(handle) &&
5959 	    jbd2_journal_extend(handle,
5960 				EXT4_DATA_TRANS_BLOCKS(inode->i_sb)) != 0)
5961 		return -ENOSPC;
5962 
5963 	if (ext4_write_trylock_xattr(inode, &no_expand) == 0)
5964 		return -EBUSY;
5965 
5966 	error = __ext4_expand_extra_isize(inode, new_extra_isize, &iloc,
5967 					  handle, &no_expand);
5968 	ext4_write_unlock_xattr(inode, &no_expand);
5969 
5970 	return error;
5971 }
5972 
5973 int ext4_expand_extra_isize(struct inode *inode,
5974 			    unsigned int new_extra_isize,
5975 			    struct ext4_iloc *iloc)
5976 {
5977 	handle_t *handle;
5978 	int no_expand;
5979 	int error, rc;
5980 
5981 	if (ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
5982 		brelse(iloc->bh);
5983 		return -EOVERFLOW;
5984 	}
5985 
5986 	handle = ext4_journal_start(inode, EXT4_HT_INODE,
5987 				    EXT4_DATA_TRANS_BLOCKS(inode->i_sb));
5988 	if (IS_ERR(handle)) {
5989 		error = PTR_ERR(handle);
5990 		brelse(iloc->bh);
5991 		return error;
5992 	}
5993 
5994 	ext4_write_lock_xattr(inode, &no_expand);
5995 
5996 	BUFFER_TRACE(iloc->bh, "get_write_access");
5997 	error = ext4_journal_get_write_access(handle, iloc->bh);
5998 	if (error) {
5999 		brelse(iloc->bh);
6000 		goto out_stop;
6001 	}
6002 
6003 	error = __ext4_expand_extra_isize(inode, new_extra_isize, iloc,
6004 					  handle, &no_expand);
6005 
6006 	rc = ext4_mark_iloc_dirty(handle, inode, iloc);
6007 	if (!error)
6008 		error = rc;
6009 
6010 	ext4_write_unlock_xattr(inode, &no_expand);
6011 out_stop:
6012 	ext4_journal_stop(handle);
6013 	return error;
6014 }
6015 
6016 /*
6017  * What we do here is to mark the in-core inode as clean with respect to inode
6018  * dirtiness (it may still be data-dirty).
6019  * This means that the in-core inode may be reaped by prune_icache
6020  * without having to perform any I/O.  This is a very good thing,
6021  * because *any* task may call prune_icache - even ones which
6022  * have a transaction open against a different journal.
6023  *
6024  * Is this cheating?  Not really.  Sure, we haven't written the
6025  * inode out, but prune_icache isn't a user-visible syncing function.
6026  * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
6027  * we start and wait on commits.
6028  */
6029 int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
6030 {
6031 	struct ext4_iloc iloc;
6032 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
6033 	int err;
6034 
6035 	might_sleep();
6036 	trace_ext4_mark_inode_dirty(inode, _RET_IP_);
6037 	err = ext4_reserve_inode_write(handle, inode, &iloc);
6038 	if (err)
6039 		return err;
6040 
6041 	if (EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize)
6042 		ext4_try_to_expand_extra_isize(inode, sbi->s_want_extra_isize,
6043 					       iloc, handle);
6044 
6045 	return ext4_mark_iloc_dirty(handle, inode, &iloc);
6046 }
6047 
6048 /*
6049  * ext4_dirty_inode() is called from __mark_inode_dirty()
6050  *
6051  * We're really interested in the case where a file is being extended.
6052  * i_size has been changed by generic_commit_write() and we thus need
6053  * to include the updated inode in the current transaction.
6054  *
6055  * Also, dquot_alloc_block() will always dirty the inode when blocks
6056  * are allocated to the file.
6057  *
6058  * If the inode is marked synchronous, we don't honour that here - doing
6059  * so would cause a commit on atime updates, which we don't bother doing.
6060  * We handle synchronous inodes at the highest possible level.
6061  *
6062  * If only the I_DIRTY_TIME flag is set, we can skip everything.  If
6063  * I_DIRTY_TIME and I_DIRTY_SYNC is set, the only inode fields we need
6064  * to copy into the on-disk inode structure are the timestamp files.
6065  */
6066 void ext4_dirty_inode(struct inode *inode, int flags)
6067 {
6068 	handle_t *handle;
6069 
6070 	if (flags == I_DIRTY_TIME)
6071 		return;
6072 	handle = ext4_journal_start(inode, EXT4_HT_INODE, 2);
6073 	if (IS_ERR(handle))
6074 		goto out;
6075 
6076 	ext4_mark_inode_dirty(handle, inode);
6077 
6078 	ext4_journal_stop(handle);
6079 out:
6080 	return;
6081 }
6082 
6083 int ext4_change_inode_journal_flag(struct inode *inode, int val)
6084 {
6085 	journal_t *journal;
6086 	handle_t *handle;
6087 	int err;
6088 	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
6089 
6090 	/*
6091 	 * We have to be very careful here: changing a data block's
6092 	 * journaling status dynamically is dangerous.  If we write a
6093 	 * data block to the journal, change the status and then delete
6094 	 * that block, we risk forgetting to revoke the old log record
6095 	 * from the journal and so a subsequent replay can corrupt data.
6096 	 * So, first we make sure that the journal is empty and that
6097 	 * nobody is changing anything.
6098 	 */
6099 
6100 	journal = EXT4_JOURNAL(inode);
6101 	if (!journal)
6102 		return 0;
6103 	if (is_journal_aborted(journal))
6104 		return -EROFS;
6105 
6106 	/* Wait for all existing dio workers */
6107 	inode_dio_wait(inode);
6108 
6109 	/*
6110 	 * Before flushing the journal and switching inode's aops, we have
6111 	 * to flush all dirty data the inode has. There can be outstanding
6112 	 * delayed allocations, there can be unwritten extents created by
6113 	 * fallocate or buffered writes in dioread_nolock mode covered by
6114 	 * dirty data which can be converted only after flushing the dirty
6115 	 * data (and journalled aops don't know how to handle these cases).
6116 	 */
6117 	if (val) {
6118 		down_write(&EXT4_I(inode)->i_mmap_sem);
6119 		err = filemap_write_and_wait(inode->i_mapping);
6120 		if (err < 0) {
6121 			up_write(&EXT4_I(inode)->i_mmap_sem);
6122 			return err;
6123 		}
6124 	}
6125 
6126 	percpu_down_write(&sbi->s_journal_flag_rwsem);
6127 	jbd2_journal_lock_updates(journal);
6128 
6129 	/*
6130 	 * OK, there are no updates running now, and all cached data is
6131 	 * synced to disk.  We are now in a completely consistent state
6132 	 * which doesn't have anything in the journal, and we know that
6133 	 * no filesystem updates are running, so it is safe to modify
6134 	 * the inode's in-core data-journaling state flag now.
6135 	 */
6136 
6137 	if (val)
6138 		ext4_set_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
6139 	else {
6140 		err = jbd2_journal_flush(journal);
6141 		if (err < 0) {
6142 			jbd2_journal_unlock_updates(journal);
6143 			percpu_up_write(&sbi->s_journal_flag_rwsem);
6144 			return err;
6145 		}
6146 		ext4_clear_inode_flag(inode, EXT4_INODE_JOURNAL_DATA);
6147 	}
6148 	ext4_set_aops(inode);
6149 
6150 	jbd2_journal_unlock_updates(journal);
6151 	percpu_up_write(&sbi->s_journal_flag_rwsem);
6152 
6153 	if (val)
6154 		up_write(&EXT4_I(inode)->i_mmap_sem);
6155 
6156 	/* Finally we can mark the inode as dirty. */
6157 
6158 	handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
6159 	if (IS_ERR(handle))
6160 		return PTR_ERR(handle);
6161 
6162 	err = ext4_mark_inode_dirty(handle, inode);
6163 	ext4_handle_sync(handle);
6164 	ext4_journal_stop(handle);
6165 	ext4_std_error(inode->i_sb, err);
6166 
6167 	return err;
6168 }
6169 
6170 static int ext4_bh_unmapped(handle_t *handle, struct buffer_head *bh)
6171 {
6172 	return !buffer_mapped(bh);
6173 }
6174 
6175 vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
6176 {
6177 	struct vm_area_struct *vma = vmf->vma;
6178 	struct page *page = vmf->page;
6179 	loff_t size;
6180 	unsigned long len;
6181 	int err;
6182 	vm_fault_t ret;
6183 	struct file *file = vma->vm_file;
6184 	struct inode *inode = file_inode(file);
6185 	struct address_space *mapping = inode->i_mapping;
6186 	handle_t *handle;
6187 	get_block_t *get_block;
6188 	int retries = 0;
6189 
6190 	sb_start_pagefault(inode->i_sb);
6191 	file_update_time(vma->vm_file);
6192 
6193 	down_read(&EXT4_I(inode)->i_mmap_sem);
6194 
6195 	err = ext4_convert_inline_data(inode);
6196 	if (err)
6197 		goto out_ret;
6198 
6199 	/* Delalloc case is easy... */
6200 	if (test_opt(inode->i_sb, DELALLOC) &&
6201 	    !ext4_should_journal_data(inode) &&
6202 	    !ext4_nonda_switch(inode->i_sb)) {
6203 		do {
6204 			err = block_page_mkwrite(vma, vmf,
6205 						   ext4_da_get_block_prep);
6206 		} while (err == -ENOSPC &&
6207 		       ext4_should_retry_alloc(inode->i_sb, &retries));
6208 		goto out_ret;
6209 	}
6210 
6211 	lock_page(page);
6212 	size = i_size_read(inode);
6213 	/* Page got truncated from under us? */
6214 	if (page->mapping != mapping || page_offset(page) > size) {
6215 		unlock_page(page);
6216 		ret = VM_FAULT_NOPAGE;
6217 		goto out;
6218 	}
6219 
6220 	if (page->index == size >> PAGE_SHIFT)
6221 		len = size & ~PAGE_MASK;
6222 	else
6223 		len = PAGE_SIZE;
6224 	/*
6225 	 * Return if we have all the buffers mapped. This avoids the need to do
6226 	 * journal_start/journal_stop which can block and take a long time
6227 	 */
6228 	if (page_has_buffers(page)) {
6229 		if (!ext4_walk_page_buffers(NULL, page_buffers(page),
6230 					    0, len, NULL,
6231 					    ext4_bh_unmapped)) {
6232 			/* Wait so that we don't change page under IO */
6233 			wait_for_stable_page(page);
6234 			ret = VM_FAULT_LOCKED;
6235 			goto out;
6236 		}
6237 	}
6238 	unlock_page(page);
6239 	/* OK, we need to fill the hole... */
6240 	if (ext4_should_dioread_nolock(inode))
6241 		get_block = ext4_get_block_unwritten;
6242 	else
6243 		get_block = ext4_get_block;
6244 retry_alloc:
6245 	handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE,
6246 				    ext4_writepage_trans_blocks(inode));
6247 	if (IS_ERR(handle)) {
6248 		ret = VM_FAULT_SIGBUS;
6249 		goto out;
6250 	}
6251 	err = block_page_mkwrite(vma, vmf, get_block);
6252 	if (!err && ext4_should_journal_data(inode)) {
6253 		if (ext4_walk_page_buffers(handle, page_buffers(page), 0,
6254 			  PAGE_SIZE, NULL, do_journal_get_write_access)) {
6255 			unlock_page(page);
6256 			ret = VM_FAULT_SIGBUS;
6257 			ext4_journal_stop(handle);
6258 			goto out;
6259 		}
6260 		ext4_set_inode_state(inode, EXT4_STATE_JDATA);
6261 	}
6262 	ext4_journal_stop(handle);
6263 	if (err == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
6264 		goto retry_alloc;
6265 out_ret:
6266 	ret = block_page_mkwrite_return(err);
6267 out:
6268 	up_read(&EXT4_I(inode)->i_mmap_sem);
6269 	sb_end_pagefault(inode->i_sb);
6270 	return ret;
6271 }
6272 
6273 vm_fault_t ext4_filemap_fault(struct vm_fault *vmf)
6274 {
6275 	struct inode *inode = file_inode(vmf->vma->vm_file);
6276 	vm_fault_t ret;
6277 
6278 	down_read(&EXT4_I(inode)->i_mmap_sem);
6279 	ret = filemap_fault(vmf);
6280 	up_read(&EXT4_I(inode)->i_mmap_sem);
6281 
6282 	return ret;
6283 }
6284