xref: /linux/fs/nilfs2/super.c (revision 34dc1baba215b826e454b8d19e4f24adbeb7d00d)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * NILFS module and super block management.
4  *
5  * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
6  *
7  * Written by Ryusuke Konishi.
8  */
9 /*
10  *  linux/fs/ext2/super.c
11  *
12  * Copyright (C) 1992, 1993, 1994, 1995
13  * Remy Card (card@masi.ibp.fr)
14  * Laboratoire MASI - Institut Blaise Pascal
15  * Universite Pierre et Marie Curie (Paris VI)
16  *
17  *  from
18  *
19  *  linux/fs/minix/inode.c
20  *
21  *  Copyright (C) 1991, 1992  Linus Torvalds
22  *
23  *  Big-endian to little-endian byte-swapping/bitmaps by
24  *        David S. Miller (davem@caip.rutgers.edu), 1995
25  */
26 
27 #include <linux/module.h>
28 #include <linux/string.h>
29 #include <linux/slab.h>
30 #include <linux/init.h>
31 #include <linux/blkdev.h>
32 #include <linux/parser.h>
33 #include <linux/crc32.h>
34 #include <linux/vfs.h>
35 #include <linux/writeback.h>
36 #include <linux/seq_file.h>
37 #include <linux/mount.h>
38 #include <linux/fs_context.h>
39 #include "nilfs.h"
40 #include "export.h"
41 #include "mdt.h"
42 #include "alloc.h"
43 #include "btree.h"
44 #include "btnode.h"
45 #include "page.h"
46 #include "cpfile.h"
47 #include "sufile.h" /* nilfs_sufile_resize(), nilfs_sufile_set_alloc_range() */
48 #include "ifile.h"
49 #include "dat.h"
50 #include "segment.h"
51 #include "segbuf.h"
52 
53 MODULE_AUTHOR("NTT Corp.");
54 MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
55 		   "(NILFS)");
56 MODULE_LICENSE("GPL");
57 
58 static struct kmem_cache *nilfs_inode_cachep;
59 struct kmem_cache *nilfs_transaction_cachep;
60 struct kmem_cache *nilfs_segbuf_cachep;
61 struct kmem_cache *nilfs_btree_path_cache;
62 
63 static int nilfs_setup_super(struct super_block *sb, int is_mount);
64 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
65 
66 void __nilfs_msg(struct super_block *sb, const char *fmt, ...)
67 {
68 	struct va_format vaf;
69 	va_list args;
70 	int level;
71 
72 	va_start(args, fmt);
73 
74 	level = printk_get_level(fmt);
75 	vaf.fmt = printk_skip_level(fmt);
76 	vaf.va = &args;
77 
78 	if (sb)
79 		printk("%c%cNILFS (%s): %pV\n",
80 		       KERN_SOH_ASCII, level, sb->s_id, &vaf);
81 	else
82 		printk("%c%cNILFS: %pV\n",
83 		       KERN_SOH_ASCII, level, &vaf);
84 
85 	va_end(args);
86 }
87 
88 static void nilfs_set_error(struct super_block *sb)
89 {
90 	struct the_nilfs *nilfs = sb->s_fs_info;
91 	struct nilfs_super_block **sbp;
92 
93 	down_write(&nilfs->ns_sem);
94 	if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
95 		nilfs->ns_mount_state |= NILFS_ERROR_FS;
96 		sbp = nilfs_prepare_super(sb, 0);
97 		if (likely(sbp)) {
98 			sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
99 			if (sbp[1])
100 				sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
101 			nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
102 		}
103 	}
104 	up_write(&nilfs->ns_sem);
105 }
106 
107 /**
108  * __nilfs_error() - report failure condition on a filesystem
109  *
110  * __nilfs_error() sets an ERROR_FS flag on the superblock as well as
111  * reporting an error message.  This function should be called when
112  * NILFS detects incoherences or defects of meta data on disk.
113  *
114  * This implements the body of nilfs_error() macro.  Normally,
115  * nilfs_error() should be used.  As for sustainable errors such as a
116  * single-shot I/O error, nilfs_err() should be used instead.
117  *
118  * Callers should not add a trailing newline since this will do it.
119  */
120 void __nilfs_error(struct super_block *sb, const char *function,
121 		   const char *fmt, ...)
122 {
123 	struct the_nilfs *nilfs = sb->s_fs_info;
124 	struct va_format vaf;
125 	va_list args;
126 
127 	va_start(args, fmt);
128 
129 	vaf.fmt = fmt;
130 	vaf.va = &args;
131 
132 	printk(KERN_CRIT "NILFS error (device %s): %s: %pV\n",
133 	       sb->s_id, function, &vaf);
134 
135 	va_end(args);
136 
137 	if (!sb_rdonly(sb)) {
138 		nilfs_set_error(sb);
139 
140 		if (nilfs_test_opt(nilfs, ERRORS_RO)) {
141 			printk(KERN_CRIT "Remounting filesystem read-only\n");
142 			sb->s_flags |= SB_RDONLY;
143 		}
144 	}
145 
146 	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
147 		panic("NILFS (device %s): panic forced after error\n",
148 		      sb->s_id);
149 }
150 
151 struct inode *nilfs_alloc_inode(struct super_block *sb)
152 {
153 	struct nilfs_inode_info *ii;
154 
155 	ii = alloc_inode_sb(sb, nilfs_inode_cachep, GFP_NOFS);
156 	if (!ii)
157 		return NULL;
158 	ii->i_bh = NULL;
159 	ii->i_state = 0;
160 	ii->i_cno = 0;
161 	ii->i_assoc_inode = NULL;
162 	ii->i_bmap = &ii->i_bmap_data;
163 	return &ii->vfs_inode;
164 }
165 
166 static void nilfs_free_inode(struct inode *inode)
167 {
168 	if (nilfs_is_metadata_file_inode(inode))
169 		nilfs_mdt_destroy(inode);
170 
171 	kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
172 }
173 
174 static int nilfs_sync_super(struct super_block *sb, int flag)
175 {
176 	struct the_nilfs *nilfs = sb->s_fs_info;
177 	int err;
178 
179  retry:
180 	set_buffer_dirty(nilfs->ns_sbh[0]);
181 	if (nilfs_test_opt(nilfs, BARRIER)) {
182 		err = __sync_dirty_buffer(nilfs->ns_sbh[0],
183 					  REQ_SYNC | REQ_PREFLUSH | REQ_FUA);
184 	} else {
185 		err = sync_dirty_buffer(nilfs->ns_sbh[0]);
186 	}
187 
188 	if (unlikely(err)) {
189 		nilfs_err(sb, "unable to write superblock: err=%d", err);
190 		if (err == -EIO && nilfs->ns_sbh[1]) {
191 			/*
192 			 * sbp[0] points to newer log than sbp[1],
193 			 * so copy sbp[0] to sbp[1] to take over sbp[0].
194 			 */
195 			memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
196 			       nilfs->ns_sbsize);
197 			nilfs_fall_back_super_block(nilfs);
198 			goto retry;
199 		}
200 	} else {
201 		struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
202 
203 		nilfs->ns_sbwcount++;
204 
205 		/*
206 		 * The latest segment becomes trailable from the position
207 		 * written in superblock.
208 		 */
209 		clear_nilfs_discontinued(nilfs);
210 
211 		/* update GC protection for recent segments */
212 		if (nilfs->ns_sbh[1]) {
213 			if (flag == NILFS_SB_COMMIT_ALL) {
214 				set_buffer_dirty(nilfs->ns_sbh[1]);
215 				if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
216 					goto out;
217 			}
218 			if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
219 			    le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
220 				sbp = nilfs->ns_sbp[1];
221 		}
222 
223 		spin_lock(&nilfs->ns_last_segment_lock);
224 		nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
225 		spin_unlock(&nilfs->ns_last_segment_lock);
226 	}
227  out:
228 	return err;
229 }
230 
231 void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
232 			  struct the_nilfs *nilfs)
233 {
234 	sector_t nfreeblocks;
235 
236 	/* nilfs->ns_sem must be locked by the caller. */
237 	nilfs_count_free_blocks(nilfs, &nfreeblocks);
238 	sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
239 
240 	spin_lock(&nilfs->ns_last_segment_lock);
241 	sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
242 	sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
243 	sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
244 	spin_unlock(&nilfs->ns_last_segment_lock);
245 }
246 
247 struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
248 					       int flip)
249 {
250 	struct the_nilfs *nilfs = sb->s_fs_info;
251 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
252 
253 	/* nilfs->ns_sem must be locked by the caller. */
254 	if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
255 		if (sbp[1] &&
256 		    sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
257 			memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
258 		} else {
259 			nilfs_crit(sb, "superblock broke");
260 			return NULL;
261 		}
262 	} else if (sbp[1] &&
263 		   sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
264 		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
265 	}
266 
267 	if (flip && sbp[1])
268 		nilfs_swap_super_block(nilfs);
269 
270 	return sbp;
271 }
272 
273 int nilfs_commit_super(struct super_block *sb, int flag)
274 {
275 	struct the_nilfs *nilfs = sb->s_fs_info;
276 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
277 	time64_t t;
278 
279 	/* nilfs->ns_sem must be locked by the caller. */
280 	t = ktime_get_real_seconds();
281 	nilfs->ns_sbwtime = t;
282 	sbp[0]->s_wtime = cpu_to_le64(t);
283 	sbp[0]->s_sum = 0;
284 	sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
285 					     (unsigned char *)sbp[0],
286 					     nilfs->ns_sbsize));
287 	if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
288 		sbp[1]->s_wtime = sbp[0]->s_wtime;
289 		sbp[1]->s_sum = 0;
290 		sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
291 					    (unsigned char *)sbp[1],
292 					    nilfs->ns_sbsize));
293 	}
294 	clear_nilfs_sb_dirty(nilfs);
295 	nilfs->ns_flushed_device = 1;
296 	/* make sure store to ns_flushed_device cannot be reordered */
297 	smp_wmb();
298 	return nilfs_sync_super(sb, flag);
299 }
300 
301 /**
302  * nilfs_cleanup_super() - write filesystem state for cleanup
303  * @sb: super block instance to be unmounted or degraded to read-only
304  *
305  * This function restores state flags in the on-disk super block.
306  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
307  * filesystem was not clean previously.
308  */
309 int nilfs_cleanup_super(struct super_block *sb)
310 {
311 	struct the_nilfs *nilfs = sb->s_fs_info;
312 	struct nilfs_super_block **sbp;
313 	int flag = NILFS_SB_COMMIT;
314 	int ret = -EIO;
315 
316 	sbp = nilfs_prepare_super(sb, 0);
317 	if (sbp) {
318 		sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
319 		nilfs_set_log_cursor(sbp[0], nilfs);
320 		if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
321 			/*
322 			 * make the "clean" flag also to the opposite
323 			 * super block if both super blocks point to
324 			 * the same checkpoint.
325 			 */
326 			sbp[1]->s_state = sbp[0]->s_state;
327 			flag = NILFS_SB_COMMIT_ALL;
328 		}
329 		ret = nilfs_commit_super(sb, flag);
330 	}
331 	return ret;
332 }
333 
334 /**
335  * nilfs_move_2nd_super - relocate secondary super block
336  * @sb: super block instance
337  * @sb2off: new offset of the secondary super block (in bytes)
338  */
339 static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
340 {
341 	struct the_nilfs *nilfs = sb->s_fs_info;
342 	struct buffer_head *nsbh;
343 	struct nilfs_super_block *nsbp;
344 	sector_t blocknr, newblocknr;
345 	unsigned long offset;
346 	int sb2i;  /* array index of the secondary superblock */
347 	int ret = 0;
348 
349 	/* nilfs->ns_sem must be locked by the caller. */
350 	if (nilfs->ns_sbh[1] &&
351 	    nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
352 		sb2i = 1;
353 		blocknr = nilfs->ns_sbh[1]->b_blocknr;
354 	} else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
355 		sb2i = 0;
356 		blocknr = nilfs->ns_sbh[0]->b_blocknr;
357 	} else {
358 		sb2i = -1;
359 		blocknr = 0;
360 	}
361 	if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
362 		goto out;  /* super block location is unchanged */
363 
364 	/* Get new super block buffer */
365 	newblocknr = sb2off >> nilfs->ns_blocksize_bits;
366 	offset = sb2off & (nilfs->ns_blocksize - 1);
367 	nsbh = sb_getblk(sb, newblocknr);
368 	if (!nsbh) {
369 		nilfs_warn(sb,
370 			   "unable to move secondary superblock to block %llu",
371 			   (unsigned long long)newblocknr);
372 		ret = -EIO;
373 		goto out;
374 	}
375 	nsbp = (void *)nsbh->b_data + offset;
376 
377 	lock_buffer(nsbh);
378 	if (sb2i >= 0) {
379 		/*
380 		 * The position of the second superblock only changes by 4KiB,
381 		 * which is larger than the maximum superblock data size
382 		 * (= 1KiB), so there is no need to use memmove() to allow
383 		 * overlap between source and destination.
384 		 */
385 		memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
386 
387 		/*
388 		 * Zero fill after copy to avoid overwriting in case of move
389 		 * within the same block.
390 		 */
391 		memset(nsbh->b_data, 0, offset);
392 		memset((void *)nsbp + nilfs->ns_sbsize, 0,
393 		       nsbh->b_size - offset - nilfs->ns_sbsize);
394 	} else {
395 		memset(nsbh->b_data, 0, nsbh->b_size);
396 	}
397 	set_buffer_uptodate(nsbh);
398 	unlock_buffer(nsbh);
399 
400 	if (sb2i >= 0) {
401 		brelse(nilfs->ns_sbh[sb2i]);
402 		nilfs->ns_sbh[sb2i] = nsbh;
403 		nilfs->ns_sbp[sb2i] = nsbp;
404 	} else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
405 		/* secondary super block will be restored to index 1 */
406 		nilfs->ns_sbh[1] = nsbh;
407 		nilfs->ns_sbp[1] = nsbp;
408 	} else {
409 		brelse(nsbh);
410 	}
411 out:
412 	return ret;
413 }
414 
415 /**
416  * nilfs_resize_fs - resize the filesystem
417  * @sb: super block instance
418  * @newsize: new size of the filesystem (in bytes)
419  */
420 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
421 {
422 	struct the_nilfs *nilfs = sb->s_fs_info;
423 	struct nilfs_super_block **sbp;
424 	__u64 devsize, newnsegs;
425 	loff_t sb2off;
426 	int ret;
427 
428 	ret = -ERANGE;
429 	devsize = bdev_nr_bytes(sb->s_bdev);
430 	if (newsize > devsize)
431 		goto out;
432 
433 	/*
434 	 * Prevent underflow in second superblock position calculation.
435 	 * The exact minimum size check is done in nilfs_sufile_resize().
436 	 */
437 	if (newsize < 4096) {
438 		ret = -ENOSPC;
439 		goto out;
440 	}
441 
442 	/*
443 	 * Write lock is required to protect some functions depending
444 	 * on the number of segments, the number of reserved segments,
445 	 * and so forth.
446 	 */
447 	down_write(&nilfs->ns_segctor_sem);
448 
449 	sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
450 	newnsegs = sb2off >> nilfs->ns_blocksize_bits;
451 	do_div(newnsegs, nilfs->ns_blocks_per_segment);
452 
453 	ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
454 	up_write(&nilfs->ns_segctor_sem);
455 	if (ret < 0)
456 		goto out;
457 
458 	ret = nilfs_construct_segment(sb);
459 	if (ret < 0)
460 		goto out;
461 
462 	down_write(&nilfs->ns_sem);
463 	nilfs_move_2nd_super(sb, sb2off);
464 	ret = -EIO;
465 	sbp = nilfs_prepare_super(sb, 0);
466 	if (likely(sbp)) {
467 		nilfs_set_log_cursor(sbp[0], nilfs);
468 		/*
469 		 * Drop NILFS_RESIZE_FS flag for compatibility with
470 		 * mount-time resize which may be implemented in a
471 		 * future release.
472 		 */
473 		sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
474 					      ~NILFS_RESIZE_FS);
475 		sbp[0]->s_dev_size = cpu_to_le64(newsize);
476 		sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
477 		if (sbp[1])
478 			memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
479 		ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
480 	}
481 	up_write(&nilfs->ns_sem);
482 
483 	/*
484 	 * Reset the range of allocatable segments last.  This order
485 	 * is important in the case of expansion because the secondary
486 	 * superblock must be protected from log write until migration
487 	 * completes.
488 	 */
489 	if (!ret)
490 		nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
491 out:
492 	return ret;
493 }
494 
495 static void nilfs_put_super(struct super_block *sb)
496 {
497 	struct the_nilfs *nilfs = sb->s_fs_info;
498 
499 	nilfs_detach_log_writer(sb);
500 
501 	if (!sb_rdonly(sb)) {
502 		down_write(&nilfs->ns_sem);
503 		nilfs_cleanup_super(sb);
504 		up_write(&nilfs->ns_sem);
505 	}
506 
507 	nilfs_sysfs_delete_device_group(nilfs);
508 	iput(nilfs->ns_sufile);
509 	iput(nilfs->ns_cpfile);
510 	iput(nilfs->ns_dat);
511 
512 	destroy_nilfs(nilfs);
513 	sb->s_fs_info = NULL;
514 }
515 
516 static int nilfs_sync_fs(struct super_block *sb, int wait)
517 {
518 	struct the_nilfs *nilfs = sb->s_fs_info;
519 	struct nilfs_super_block **sbp;
520 	int err = 0;
521 
522 	/* This function is called when super block should be written back */
523 	if (wait)
524 		err = nilfs_construct_segment(sb);
525 
526 	down_write(&nilfs->ns_sem);
527 	if (nilfs_sb_dirty(nilfs)) {
528 		sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
529 		if (likely(sbp)) {
530 			nilfs_set_log_cursor(sbp[0], nilfs);
531 			nilfs_commit_super(sb, NILFS_SB_COMMIT);
532 		}
533 	}
534 	up_write(&nilfs->ns_sem);
535 
536 	if (!err)
537 		err = nilfs_flush_device(nilfs);
538 
539 	return err;
540 }
541 
542 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
543 			    struct nilfs_root **rootp)
544 {
545 	struct the_nilfs *nilfs = sb->s_fs_info;
546 	struct nilfs_root *root;
547 	struct nilfs_checkpoint *raw_cp;
548 	struct buffer_head *bh_cp;
549 	int err = -ENOMEM;
550 
551 	root = nilfs_find_or_create_root(
552 		nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
553 	if (!root)
554 		return err;
555 
556 	if (root->ifile)
557 		goto reuse; /* already attached checkpoint */
558 
559 	down_read(&nilfs->ns_segctor_sem);
560 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
561 					  &bh_cp);
562 	up_read(&nilfs->ns_segctor_sem);
563 	if (unlikely(err)) {
564 		if (err == -ENOENT || err == -EINVAL) {
565 			nilfs_err(sb,
566 				  "Invalid checkpoint (checkpoint number=%llu)",
567 				  (unsigned long long)cno);
568 			err = -EINVAL;
569 		}
570 		goto failed;
571 	}
572 
573 	err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
574 			       &raw_cp->cp_ifile_inode, &root->ifile);
575 	if (err)
576 		goto failed_bh;
577 
578 	atomic64_set(&root->inodes_count,
579 			le64_to_cpu(raw_cp->cp_inodes_count));
580 	atomic64_set(&root->blocks_count,
581 			le64_to_cpu(raw_cp->cp_blocks_count));
582 
583 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
584 
585  reuse:
586 	*rootp = root;
587 	return 0;
588 
589  failed_bh:
590 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
591  failed:
592 	nilfs_put_root(root);
593 
594 	return err;
595 }
596 
597 static int nilfs_freeze(struct super_block *sb)
598 {
599 	struct the_nilfs *nilfs = sb->s_fs_info;
600 	int err;
601 
602 	if (sb_rdonly(sb))
603 		return 0;
604 
605 	/* Mark super block clean */
606 	down_write(&nilfs->ns_sem);
607 	err = nilfs_cleanup_super(sb);
608 	up_write(&nilfs->ns_sem);
609 	return err;
610 }
611 
612 static int nilfs_unfreeze(struct super_block *sb)
613 {
614 	struct the_nilfs *nilfs = sb->s_fs_info;
615 
616 	if (sb_rdonly(sb))
617 		return 0;
618 
619 	down_write(&nilfs->ns_sem);
620 	nilfs_setup_super(sb, false);
621 	up_write(&nilfs->ns_sem);
622 	return 0;
623 }
624 
625 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
626 {
627 	struct super_block *sb = dentry->d_sb;
628 	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
629 	struct the_nilfs *nilfs = root->nilfs;
630 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
631 	unsigned long long blocks;
632 	unsigned long overhead;
633 	unsigned long nrsvblocks;
634 	sector_t nfreeblocks;
635 	u64 nmaxinodes, nfreeinodes;
636 	int err;
637 
638 	/*
639 	 * Compute all of the segment blocks
640 	 *
641 	 * The blocks before first segment and after last segment
642 	 * are excluded.
643 	 */
644 	blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
645 		- nilfs->ns_first_data_block;
646 	nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
647 
648 	/*
649 	 * Compute the overhead
650 	 *
651 	 * When distributing meta data blocks outside segment structure,
652 	 * We must count them as the overhead.
653 	 */
654 	overhead = 0;
655 
656 	err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
657 	if (unlikely(err))
658 		return err;
659 
660 	err = nilfs_ifile_count_free_inodes(root->ifile,
661 					    &nmaxinodes, &nfreeinodes);
662 	if (unlikely(err)) {
663 		nilfs_warn(sb, "failed to count free inodes: err=%d", err);
664 		if (err == -ERANGE) {
665 			/*
666 			 * If nilfs_palloc_count_max_entries() returns
667 			 * -ERANGE error code then we simply treat
668 			 * curent inodes count as maximum possible and
669 			 * zero as free inodes value.
670 			 */
671 			nmaxinodes = atomic64_read(&root->inodes_count);
672 			nfreeinodes = 0;
673 			err = 0;
674 		} else
675 			return err;
676 	}
677 
678 	buf->f_type = NILFS_SUPER_MAGIC;
679 	buf->f_bsize = sb->s_blocksize;
680 	buf->f_blocks = blocks - overhead;
681 	buf->f_bfree = nfreeblocks;
682 	buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
683 		(buf->f_bfree - nrsvblocks) : 0;
684 	buf->f_files = nmaxinodes;
685 	buf->f_ffree = nfreeinodes;
686 	buf->f_namelen = NILFS_NAME_LEN;
687 	buf->f_fsid = u64_to_fsid(id);
688 
689 	return 0;
690 }
691 
692 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
693 {
694 	struct super_block *sb = dentry->d_sb;
695 	struct the_nilfs *nilfs = sb->s_fs_info;
696 	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
697 
698 	if (!nilfs_test_opt(nilfs, BARRIER))
699 		seq_puts(seq, ",nobarrier");
700 	if (root->cno != NILFS_CPTREE_CURRENT_CNO)
701 		seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
702 	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
703 		seq_puts(seq, ",errors=panic");
704 	if (nilfs_test_opt(nilfs, ERRORS_CONT))
705 		seq_puts(seq, ",errors=continue");
706 	if (nilfs_test_opt(nilfs, STRICT_ORDER))
707 		seq_puts(seq, ",order=strict");
708 	if (nilfs_test_opt(nilfs, NORECOVERY))
709 		seq_puts(seq, ",norecovery");
710 	if (nilfs_test_opt(nilfs, DISCARD))
711 		seq_puts(seq, ",discard");
712 
713 	return 0;
714 }
715 
716 static const struct super_operations nilfs_sops = {
717 	.alloc_inode    = nilfs_alloc_inode,
718 	.free_inode     = nilfs_free_inode,
719 	.dirty_inode    = nilfs_dirty_inode,
720 	.evict_inode    = nilfs_evict_inode,
721 	.put_super      = nilfs_put_super,
722 	.sync_fs        = nilfs_sync_fs,
723 	.freeze_fs	= nilfs_freeze,
724 	.unfreeze_fs	= nilfs_unfreeze,
725 	.statfs         = nilfs_statfs,
726 	.remount_fs     = nilfs_remount,
727 	.show_options = nilfs_show_options
728 };
729 
730 enum {
731 	Opt_err_cont, Opt_err_panic, Opt_err_ro,
732 	Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
733 	Opt_discard, Opt_nodiscard, Opt_err,
734 };
735 
736 static match_table_t tokens = {
737 	{Opt_err_cont, "errors=continue"},
738 	{Opt_err_panic, "errors=panic"},
739 	{Opt_err_ro, "errors=remount-ro"},
740 	{Opt_barrier, "barrier"},
741 	{Opt_nobarrier, "nobarrier"},
742 	{Opt_snapshot, "cp=%u"},
743 	{Opt_order, "order=%s"},
744 	{Opt_norecovery, "norecovery"},
745 	{Opt_discard, "discard"},
746 	{Opt_nodiscard, "nodiscard"},
747 	{Opt_err, NULL}
748 };
749 
750 static int parse_options(char *options, struct super_block *sb, int is_remount)
751 {
752 	struct the_nilfs *nilfs = sb->s_fs_info;
753 	char *p;
754 	substring_t args[MAX_OPT_ARGS];
755 
756 	if (!options)
757 		return 1;
758 
759 	while ((p = strsep(&options, ",")) != NULL) {
760 		int token;
761 
762 		if (!*p)
763 			continue;
764 
765 		token = match_token(p, tokens, args);
766 		switch (token) {
767 		case Opt_barrier:
768 			nilfs_set_opt(nilfs, BARRIER);
769 			break;
770 		case Opt_nobarrier:
771 			nilfs_clear_opt(nilfs, BARRIER);
772 			break;
773 		case Opt_order:
774 			if (strcmp(args[0].from, "relaxed") == 0)
775 				/* Ordered data semantics */
776 				nilfs_clear_opt(nilfs, STRICT_ORDER);
777 			else if (strcmp(args[0].from, "strict") == 0)
778 				/* Strict in-order semantics */
779 				nilfs_set_opt(nilfs, STRICT_ORDER);
780 			else
781 				return 0;
782 			break;
783 		case Opt_err_panic:
784 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
785 			break;
786 		case Opt_err_ro:
787 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
788 			break;
789 		case Opt_err_cont:
790 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
791 			break;
792 		case Opt_snapshot:
793 			if (is_remount) {
794 				nilfs_err(sb,
795 					  "\"%s\" option is invalid for remount",
796 					  p);
797 				return 0;
798 			}
799 			break;
800 		case Opt_norecovery:
801 			nilfs_set_opt(nilfs, NORECOVERY);
802 			break;
803 		case Opt_discard:
804 			nilfs_set_opt(nilfs, DISCARD);
805 			break;
806 		case Opt_nodiscard:
807 			nilfs_clear_opt(nilfs, DISCARD);
808 			break;
809 		default:
810 			nilfs_err(sb, "unrecognized mount option \"%s\"", p);
811 			return 0;
812 		}
813 	}
814 	return 1;
815 }
816 
817 static inline void
818 nilfs_set_default_options(struct super_block *sb,
819 			  struct nilfs_super_block *sbp)
820 {
821 	struct the_nilfs *nilfs = sb->s_fs_info;
822 
823 	nilfs->ns_mount_opt =
824 		NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
825 }
826 
827 static int nilfs_setup_super(struct super_block *sb, int is_mount)
828 {
829 	struct the_nilfs *nilfs = sb->s_fs_info;
830 	struct nilfs_super_block **sbp;
831 	int max_mnt_count;
832 	int mnt_count;
833 
834 	/* nilfs->ns_sem must be locked by the caller. */
835 	sbp = nilfs_prepare_super(sb, 0);
836 	if (!sbp)
837 		return -EIO;
838 
839 	if (!is_mount)
840 		goto skip_mount_setup;
841 
842 	max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
843 	mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
844 
845 	if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
846 		nilfs_warn(sb, "mounting fs with errors");
847 #if 0
848 	} else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
849 		nilfs_warn(sb, "maximal mount count reached");
850 #endif
851 	}
852 	if (!max_mnt_count)
853 		sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
854 
855 	sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
856 	sbp[0]->s_mtime = cpu_to_le64(ktime_get_real_seconds());
857 
858 skip_mount_setup:
859 	sbp[0]->s_state =
860 		cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
861 	/* synchronize sbp[1] with sbp[0] */
862 	if (sbp[1])
863 		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
864 	return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
865 }
866 
867 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
868 						 u64 pos, int blocksize,
869 						 struct buffer_head **pbh)
870 {
871 	unsigned long long sb_index = pos;
872 	unsigned long offset;
873 
874 	offset = do_div(sb_index, blocksize);
875 	*pbh = sb_bread(sb, sb_index);
876 	if (!*pbh)
877 		return NULL;
878 	return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
879 }
880 
881 int nilfs_store_magic_and_option(struct super_block *sb,
882 				 struct nilfs_super_block *sbp,
883 				 char *data)
884 {
885 	struct the_nilfs *nilfs = sb->s_fs_info;
886 
887 	sb->s_magic = le16_to_cpu(sbp->s_magic);
888 
889 	/* FS independent flags */
890 #ifdef NILFS_ATIME_DISABLE
891 	sb->s_flags |= SB_NOATIME;
892 #endif
893 
894 	nilfs_set_default_options(sb, sbp);
895 
896 	nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
897 	nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
898 	nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
899 	nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
900 
901 	return !parse_options(data, sb, 0) ? -EINVAL : 0;
902 }
903 
904 int nilfs_check_feature_compatibility(struct super_block *sb,
905 				      struct nilfs_super_block *sbp)
906 {
907 	__u64 features;
908 
909 	features = le64_to_cpu(sbp->s_feature_incompat) &
910 		~NILFS_FEATURE_INCOMPAT_SUPP;
911 	if (features) {
912 		nilfs_err(sb,
913 			  "couldn't mount because of unsupported optional features (%llx)",
914 			  (unsigned long long)features);
915 		return -EINVAL;
916 	}
917 	features = le64_to_cpu(sbp->s_feature_compat_ro) &
918 		~NILFS_FEATURE_COMPAT_RO_SUPP;
919 	if (!sb_rdonly(sb) && features) {
920 		nilfs_err(sb,
921 			  "couldn't mount RDWR because of unsupported optional features (%llx)",
922 			  (unsigned long long)features);
923 		return -EINVAL;
924 	}
925 	return 0;
926 }
927 
928 static int nilfs_get_root_dentry(struct super_block *sb,
929 				 struct nilfs_root *root,
930 				 struct dentry **root_dentry)
931 {
932 	struct inode *inode;
933 	struct dentry *dentry;
934 	int ret = 0;
935 
936 	inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
937 	if (IS_ERR(inode)) {
938 		ret = PTR_ERR(inode);
939 		nilfs_err(sb, "error %d getting root inode", ret);
940 		goto out;
941 	}
942 	if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
943 		iput(inode);
944 		nilfs_err(sb, "corrupt root inode");
945 		ret = -EINVAL;
946 		goto out;
947 	}
948 
949 	if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
950 		dentry = d_find_alias(inode);
951 		if (!dentry) {
952 			dentry = d_make_root(inode);
953 			if (!dentry) {
954 				ret = -ENOMEM;
955 				goto failed_dentry;
956 			}
957 		} else {
958 			iput(inode);
959 		}
960 	} else {
961 		dentry = d_obtain_root(inode);
962 		if (IS_ERR(dentry)) {
963 			ret = PTR_ERR(dentry);
964 			goto failed_dentry;
965 		}
966 	}
967 	*root_dentry = dentry;
968  out:
969 	return ret;
970 
971  failed_dentry:
972 	nilfs_err(sb, "error %d getting root dentry", ret);
973 	goto out;
974 }
975 
976 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
977 				 struct dentry **root_dentry)
978 {
979 	struct the_nilfs *nilfs = s->s_fs_info;
980 	struct nilfs_root *root;
981 	int ret;
982 
983 	mutex_lock(&nilfs->ns_snapshot_mount_mutex);
984 
985 	down_read(&nilfs->ns_segctor_sem);
986 	ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
987 	up_read(&nilfs->ns_segctor_sem);
988 	if (ret < 0) {
989 		ret = (ret == -ENOENT) ? -EINVAL : ret;
990 		goto out;
991 	} else if (!ret) {
992 		nilfs_err(s,
993 			  "The specified checkpoint is not a snapshot (checkpoint number=%llu)",
994 			  (unsigned long long)cno);
995 		ret = -EINVAL;
996 		goto out;
997 	}
998 
999 	ret = nilfs_attach_checkpoint(s, cno, false, &root);
1000 	if (ret) {
1001 		nilfs_err(s,
1002 			  "error %d while loading snapshot (checkpoint number=%llu)",
1003 			  ret, (unsigned long long)cno);
1004 		goto out;
1005 	}
1006 	ret = nilfs_get_root_dentry(s, root, root_dentry);
1007 	nilfs_put_root(root);
1008  out:
1009 	mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
1010 	return ret;
1011 }
1012 
1013 /**
1014  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
1015  * @root_dentry: root dentry of the tree to be shrunk
1016  *
1017  * This function returns true if the tree was in-use.
1018  */
1019 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
1020 {
1021 	shrink_dcache_parent(root_dentry);
1022 	return d_count(root_dentry) > 1;
1023 }
1024 
1025 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1026 {
1027 	struct the_nilfs *nilfs = sb->s_fs_info;
1028 	struct nilfs_root *root;
1029 	struct inode *inode;
1030 	struct dentry *dentry;
1031 	int ret;
1032 
1033 	if (cno > nilfs->ns_cno)
1034 		return false;
1035 
1036 	if (cno >= nilfs_last_cno(nilfs))
1037 		return true;	/* protect recent checkpoints */
1038 
1039 	ret = false;
1040 	root = nilfs_lookup_root(nilfs, cno);
1041 	if (root) {
1042 		inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1043 		if (inode) {
1044 			dentry = d_find_alias(inode);
1045 			if (dentry) {
1046 				ret = nilfs_tree_is_busy(dentry);
1047 				dput(dentry);
1048 			}
1049 			iput(inode);
1050 		}
1051 		nilfs_put_root(root);
1052 	}
1053 	return ret;
1054 }
1055 
1056 /**
1057  * nilfs_fill_super() - initialize a super block instance
1058  * @sb: super_block
1059  * @data: mount options
1060  * @silent: silent mode flag
1061  *
1062  * This function is called exclusively by nilfs->ns_mount_mutex.
1063  * So, the recovery process is protected from other simultaneous mounts.
1064  */
1065 static int
1066 nilfs_fill_super(struct super_block *sb, void *data, int silent)
1067 {
1068 	struct the_nilfs *nilfs;
1069 	struct nilfs_root *fsroot;
1070 	__u64 cno;
1071 	int err;
1072 
1073 	nilfs = alloc_nilfs(sb);
1074 	if (!nilfs)
1075 		return -ENOMEM;
1076 
1077 	sb->s_fs_info = nilfs;
1078 
1079 	err = init_nilfs(nilfs, sb, (char *)data);
1080 	if (err)
1081 		goto failed_nilfs;
1082 
1083 	sb->s_op = &nilfs_sops;
1084 	sb->s_export_op = &nilfs_export_ops;
1085 	sb->s_root = NULL;
1086 	sb->s_time_gran = 1;
1087 	sb->s_max_links = NILFS_LINK_MAX;
1088 
1089 	sb->s_bdi = bdi_get(sb->s_bdev->bd_disk->bdi);
1090 
1091 	err = load_nilfs(nilfs, sb);
1092 	if (err)
1093 		goto failed_nilfs;
1094 
1095 	cno = nilfs_last_cno(nilfs);
1096 	err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1097 	if (err) {
1098 		nilfs_err(sb,
1099 			  "error %d while loading last checkpoint (checkpoint number=%llu)",
1100 			  err, (unsigned long long)cno);
1101 		goto failed_unload;
1102 	}
1103 
1104 	if (!sb_rdonly(sb)) {
1105 		err = nilfs_attach_log_writer(sb, fsroot);
1106 		if (err)
1107 			goto failed_checkpoint;
1108 	}
1109 
1110 	err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1111 	if (err)
1112 		goto failed_segctor;
1113 
1114 	nilfs_put_root(fsroot);
1115 
1116 	if (!sb_rdonly(sb)) {
1117 		down_write(&nilfs->ns_sem);
1118 		nilfs_setup_super(sb, true);
1119 		up_write(&nilfs->ns_sem);
1120 	}
1121 
1122 	return 0;
1123 
1124  failed_segctor:
1125 	nilfs_detach_log_writer(sb);
1126 
1127  failed_checkpoint:
1128 	nilfs_put_root(fsroot);
1129 
1130  failed_unload:
1131 	nilfs_sysfs_delete_device_group(nilfs);
1132 	iput(nilfs->ns_sufile);
1133 	iput(nilfs->ns_cpfile);
1134 	iput(nilfs->ns_dat);
1135 
1136  failed_nilfs:
1137 	destroy_nilfs(nilfs);
1138 	return err;
1139 }
1140 
1141 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1142 {
1143 	struct the_nilfs *nilfs = sb->s_fs_info;
1144 	unsigned long old_sb_flags;
1145 	unsigned long old_mount_opt;
1146 	int err;
1147 
1148 	sync_filesystem(sb);
1149 	old_sb_flags = sb->s_flags;
1150 	old_mount_opt = nilfs->ns_mount_opt;
1151 
1152 	if (!parse_options(data, sb, 1)) {
1153 		err = -EINVAL;
1154 		goto restore_opts;
1155 	}
1156 	sb->s_flags = (sb->s_flags & ~SB_POSIXACL);
1157 
1158 	err = -EINVAL;
1159 
1160 	if (!nilfs_valid_fs(nilfs)) {
1161 		nilfs_warn(sb,
1162 			   "couldn't remount because the filesystem is in an incomplete recovery state");
1163 		goto restore_opts;
1164 	}
1165 
1166 	if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
1167 		goto out;
1168 	if (*flags & SB_RDONLY) {
1169 		sb->s_flags |= SB_RDONLY;
1170 
1171 		/*
1172 		 * Remounting a valid RW partition RDONLY, so set
1173 		 * the RDONLY flag and then mark the partition as valid again.
1174 		 */
1175 		down_write(&nilfs->ns_sem);
1176 		nilfs_cleanup_super(sb);
1177 		up_write(&nilfs->ns_sem);
1178 	} else {
1179 		__u64 features;
1180 		struct nilfs_root *root;
1181 
1182 		/*
1183 		 * Mounting a RDONLY partition read-write, so reread and
1184 		 * store the current valid flag.  (It may have been changed
1185 		 * by fsck since we originally mounted the partition.)
1186 		 */
1187 		down_read(&nilfs->ns_sem);
1188 		features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1189 			~NILFS_FEATURE_COMPAT_RO_SUPP;
1190 		up_read(&nilfs->ns_sem);
1191 		if (features) {
1192 			nilfs_warn(sb,
1193 				   "couldn't remount RDWR because of unsupported optional features (%llx)",
1194 				   (unsigned long long)features);
1195 			err = -EROFS;
1196 			goto restore_opts;
1197 		}
1198 
1199 		sb->s_flags &= ~SB_RDONLY;
1200 
1201 		root = NILFS_I(d_inode(sb->s_root))->i_root;
1202 		err = nilfs_attach_log_writer(sb, root);
1203 		if (err)
1204 			goto restore_opts;
1205 
1206 		down_write(&nilfs->ns_sem);
1207 		nilfs_setup_super(sb, true);
1208 		up_write(&nilfs->ns_sem);
1209 	}
1210  out:
1211 	return 0;
1212 
1213  restore_opts:
1214 	sb->s_flags = old_sb_flags;
1215 	nilfs->ns_mount_opt = old_mount_opt;
1216 	return err;
1217 }
1218 
1219 struct nilfs_super_data {
1220 	__u64 cno;
1221 	int flags;
1222 };
1223 
1224 static int nilfs_parse_snapshot_option(const char *option,
1225 				       const substring_t *arg,
1226 				       struct nilfs_super_data *sd)
1227 {
1228 	unsigned long long val;
1229 	const char *msg = NULL;
1230 	int err;
1231 
1232 	if (!(sd->flags & SB_RDONLY)) {
1233 		msg = "read-only option is not specified";
1234 		goto parse_error;
1235 	}
1236 
1237 	err = kstrtoull(arg->from, 0, &val);
1238 	if (err) {
1239 		if (err == -ERANGE)
1240 			msg = "too large checkpoint number";
1241 		else
1242 			msg = "malformed argument";
1243 		goto parse_error;
1244 	} else if (val == 0) {
1245 		msg = "invalid checkpoint number 0";
1246 		goto parse_error;
1247 	}
1248 	sd->cno = val;
1249 	return 0;
1250 
1251 parse_error:
1252 	nilfs_err(NULL, "invalid option \"%s\": %s", option, msg);
1253 	return 1;
1254 }
1255 
1256 /**
1257  * nilfs_identify - pre-read mount options needed to identify mount instance
1258  * @data: mount options
1259  * @sd: nilfs_super_data
1260  */
1261 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1262 {
1263 	char *p, *options = data;
1264 	substring_t args[MAX_OPT_ARGS];
1265 	int token;
1266 	int ret = 0;
1267 
1268 	do {
1269 		p = strsep(&options, ",");
1270 		if (p != NULL && *p) {
1271 			token = match_token(p, tokens, args);
1272 			if (token == Opt_snapshot)
1273 				ret = nilfs_parse_snapshot_option(p, &args[0],
1274 								  sd);
1275 		}
1276 		if (!options)
1277 			break;
1278 		BUG_ON(options == data);
1279 		*(options - 1) = ',';
1280 	} while (!ret);
1281 	return ret;
1282 }
1283 
1284 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1285 {
1286 	s->s_dev = *(dev_t *)data;
1287 	return 0;
1288 }
1289 
1290 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1291 {
1292 	return !(s->s_iflags & SB_I_RETIRED) && s->s_dev == *(dev_t *)data;
1293 }
1294 
1295 static struct dentry *
1296 nilfs_mount(struct file_system_type *fs_type, int flags,
1297 	     const char *dev_name, void *data)
1298 {
1299 	struct nilfs_super_data sd = { .flags = flags };
1300 	struct super_block *s;
1301 	dev_t dev;
1302 	int err;
1303 
1304 	if (nilfs_identify(data, &sd))
1305 		return ERR_PTR(-EINVAL);
1306 
1307 	err = lookup_bdev(dev_name, &dev);
1308 	if (err)
1309 		return ERR_PTR(err);
1310 
1311 	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
1312 		 &dev);
1313 	if (IS_ERR(s))
1314 		return ERR_CAST(s);
1315 
1316 	if (!s->s_root) {
1317 		/*
1318 		 * We drop s_umount here because we need to open the bdev and
1319 		 * bdev->open_mutex ranks above s_umount (blkdev_put() ->
1320 		 * __invalidate_device()). It is safe because we have active sb
1321 		 * reference and SB_BORN is not set yet.
1322 		 */
1323 		up_write(&s->s_umount);
1324 		err = setup_bdev_super(s, flags, NULL);
1325 		down_write(&s->s_umount);
1326 		if (!err)
1327 			err = nilfs_fill_super(s, data,
1328 					       flags & SB_SILENT ? 1 : 0);
1329 		if (err)
1330 			goto failed_super;
1331 
1332 		s->s_flags |= SB_ACTIVE;
1333 	} else if (!sd.cno) {
1334 		if (nilfs_tree_is_busy(s->s_root)) {
1335 			if ((flags ^ s->s_flags) & SB_RDONLY) {
1336 				nilfs_err(s,
1337 					  "the device already has a %s mount.",
1338 					  sb_rdonly(s) ? "read-only" : "read/write");
1339 				err = -EBUSY;
1340 				goto failed_super;
1341 			}
1342 		} else {
1343 			/*
1344 			 * Try remount to setup mount states if the current
1345 			 * tree is not mounted and only snapshots use this sb.
1346 			 */
1347 			err = nilfs_remount(s, &flags, data);
1348 			if (err)
1349 				goto failed_super;
1350 		}
1351 	}
1352 
1353 	if (sd.cno) {
1354 		struct dentry *root_dentry;
1355 
1356 		err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1357 		if (err)
1358 			goto failed_super;
1359 		return root_dentry;
1360 	}
1361 
1362 	return dget(s->s_root);
1363 
1364  failed_super:
1365 	deactivate_locked_super(s);
1366 	return ERR_PTR(err);
1367 }
1368 
1369 struct file_system_type nilfs_fs_type = {
1370 	.owner    = THIS_MODULE,
1371 	.name     = "nilfs2",
1372 	.mount    = nilfs_mount,
1373 	.kill_sb  = kill_block_super,
1374 	.fs_flags = FS_REQUIRES_DEV,
1375 };
1376 MODULE_ALIAS_FS("nilfs2");
1377 
1378 static void nilfs_inode_init_once(void *obj)
1379 {
1380 	struct nilfs_inode_info *ii = obj;
1381 
1382 	INIT_LIST_HEAD(&ii->i_dirty);
1383 #ifdef CONFIG_NILFS_XATTR
1384 	init_rwsem(&ii->xattr_sem);
1385 #endif
1386 	inode_init_once(&ii->vfs_inode);
1387 }
1388 
1389 static void nilfs_segbuf_init_once(void *obj)
1390 {
1391 	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1392 }
1393 
1394 static void nilfs_destroy_cachep(void)
1395 {
1396 	/*
1397 	 * Make sure all delayed rcu free inodes are flushed before we
1398 	 * destroy cache.
1399 	 */
1400 	rcu_barrier();
1401 
1402 	kmem_cache_destroy(nilfs_inode_cachep);
1403 	kmem_cache_destroy(nilfs_transaction_cachep);
1404 	kmem_cache_destroy(nilfs_segbuf_cachep);
1405 	kmem_cache_destroy(nilfs_btree_path_cache);
1406 }
1407 
1408 static int __init nilfs_init_cachep(void)
1409 {
1410 	nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1411 			sizeof(struct nilfs_inode_info), 0,
1412 			SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
1413 			nilfs_inode_init_once);
1414 	if (!nilfs_inode_cachep)
1415 		goto fail;
1416 
1417 	nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1418 			sizeof(struct nilfs_transaction_info), 0,
1419 			SLAB_RECLAIM_ACCOUNT, NULL);
1420 	if (!nilfs_transaction_cachep)
1421 		goto fail;
1422 
1423 	nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1424 			sizeof(struct nilfs_segment_buffer), 0,
1425 			SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1426 	if (!nilfs_segbuf_cachep)
1427 		goto fail;
1428 
1429 	nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1430 			sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1431 			0, 0, NULL);
1432 	if (!nilfs_btree_path_cache)
1433 		goto fail;
1434 
1435 	return 0;
1436 
1437 fail:
1438 	nilfs_destroy_cachep();
1439 	return -ENOMEM;
1440 }
1441 
1442 static int __init init_nilfs_fs(void)
1443 {
1444 	int err;
1445 
1446 	err = nilfs_init_cachep();
1447 	if (err)
1448 		goto fail;
1449 
1450 	err = nilfs_sysfs_init();
1451 	if (err)
1452 		goto free_cachep;
1453 
1454 	err = register_filesystem(&nilfs_fs_type);
1455 	if (err)
1456 		goto deinit_sysfs_entry;
1457 
1458 	printk(KERN_INFO "NILFS version 2 loaded\n");
1459 	return 0;
1460 
1461 deinit_sysfs_entry:
1462 	nilfs_sysfs_exit();
1463 free_cachep:
1464 	nilfs_destroy_cachep();
1465 fail:
1466 	return err;
1467 }
1468 
1469 static void __exit exit_nilfs_fs(void)
1470 {
1471 	nilfs_destroy_cachep();
1472 	nilfs_sysfs_exit();
1473 	unregister_filesystem(&nilfs_fs_type);
1474 }
1475 
1476 module_init(init_nilfs_fs)
1477 module_exit(exit_nilfs_fs)
1478