xref: /linux/fs/nilfs2/super.c (revision e7cd4b811c9e019f5acbce85699c622b30194c24)
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/crc32.h>
33 #include <linux/vfs.h>
34 #include <linux/writeback.h>
35 #include <linux/seq_file.h>
36 #include <linux/mount.h>
37 #include <linux/fs_context.h>
38 #include <linux/fs_parser.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 
65 void __nilfs_msg(struct super_block *sb, const char *fmt, ...)
66 {
67 	struct va_format vaf;
68 	va_list args;
69 	int level;
70 
71 	va_start(args, fmt);
72 
73 	level = printk_get_level(fmt);
74 	vaf.fmt = printk_skip_level(fmt);
75 	vaf.va = &args;
76 
77 	if (sb)
78 		printk("%c%cNILFS (%s): %pV\n",
79 		       KERN_SOH_ASCII, level, sb->s_id, &vaf);
80 	else
81 		printk("%c%cNILFS: %pV\n",
82 		       KERN_SOH_ASCII, level, &vaf);
83 
84 	va_end(args);
85 }
86 
87 static void nilfs_set_error(struct super_block *sb)
88 {
89 	struct the_nilfs *nilfs = sb->s_fs_info;
90 	struct nilfs_super_block **sbp;
91 
92 	down_write(&nilfs->ns_sem);
93 	if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
94 		nilfs->ns_mount_state |= NILFS_ERROR_FS;
95 		sbp = nilfs_prepare_super(sb, 0);
96 		if (likely(sbp)) {
97 			sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
98 			if (sbp[1])
99 				sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
100 			nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
101 		}
102 	}
103 	up_write(&nilfs->ns_sem);
104 }
105 
106 /**
107  * __nilfs_error() - report failure condition on a filesystem
108  * @sb:       super block instance
109  * @function: name of calling function
110  * @fmt:      format string for message to be output
111  * @...:      optional arguments to @fmt
112  *
113  * __nilfs_error() sets an ERROR_FS flag on the superblock as well as
114  * reporting an error message.  This function should be called when
115  * NILFS detects incoherences or defects of meta data on disk.
116  *
117  * This implements the body of nilfs_error() macro.  Normally,
118  * nilfs_error() should be used.  As for sustainable errors such as a
119  * single-shot I/O error, nilfs_err() should be used instead.
120  *
121  * Callers should not add a trailing newline since this will do it.
122  */
123 void __nilfs_error(struct super_block *sb, const char *function,
124 		   const char *fmt, ...)
125 {
126 	struct the_nilfs *nilfs = sb->s_fs_info;
127 	struct va_format vaf;
128 	va_list args;
129 
130 	va_start(args, fmt);
131 
132 	vaf.fmt = fmt;
133 	vaf.va = &args;
134 
135 	printk(KERN_CRIT "NILFS error (device %s): %s: %pV\n",
136 	       sb->s_id, function, &vaf);
137 
138 	va_end(args);
139 
140 	if (!sb_rdonly(sb)) {
141 		nilfs_set_error(sb);
142 
143 		if (nilfs_test_opt(nilfs, ERRORS_RO)) {
144 			printk(KERN_CRIT "Remounting filesystem read-only\n");
145 			sb->s_flags |= SB_RDONLY;
146 		}
147 	}
148 
149 	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
150 		panic("NILFS (device %s): panic forced after error\n",
151 		      sb->s_id);
152 }
153 
154 struct inode *nilfs_alloc_inode(struct super_block *sb)
155 {
156 	struct nilfs_inode_info *ii;
157 
158 	ii = alloc_inode_sb(sb, nilfs_inode_cachep, GFP_NOFS);
159 	if (!ii)
160 		return NULL;
161 	ii->i_bh = NULL;
162 	ii->i_state = 0;
163 	ii->i_type = 0;
164 	ii->i_cno = 0;
165 	ii->i_assoc_inode = NULL;
166 	ii->i_bmap = &ii->i_bmap_data;
167 	return &ii->vfs_inode;
168 }
169 
170 static void nilfs_free_inode(struct inode *inode)
171 {
172 	if (nilfs_is_metadata_file_inode(inode))
173 		nilfs_mdt_destroy(inode);
174 
175 	kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
176 }
177 
178 static int nilfs_sync_super(struct super_block *sb, int flag)
179 {
180 	struct the_nilfs *nilfs = sb->s_fs_info;
181 	int err;
182 
183  retry:
184 	set_buffer_dirty(nilfs->ns_sbh[0]);
185 	if (nilfs_test_opt(nilfs, BARRIER)) {
186 		err = __sync_dirty_buffer(nilfs->ns_sbh[0],
187 					  REQ_SYNC | REQ_PREFLUSH | REQ_FUA);
188 	} else {
189 		err = sync_dirty_buffer(nilfs->ns_sbh[0]);
190 	}
191 
192 	if (unlikely(err)) {
193 		nilfs_err(sb, "unable to write superblock: err=%d", err);
194 		if (err == -EIO && nilfs->ns_sbh[1]) {
195 			/*
196 			 * sbp[0] points to newer log than sbp[1],
197 			 * so copy sbp[0] to sbp[1] to take over sbp[0].
198 			 */
199 			memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
200 			       nilfs->ns_sbsize);
201 			nilfs_fall_back_super_block(nilfs);
202 			goto retry;
203 		}
204 	} else {
205 		struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
206 
207 		nilfs->ns_sbwcount++;
208 
209 		/*
210 		 * The latest segment becomes trailable from the position
211 		 * written in superblock.
212 		 */
213 		clear_nilfs_discontinued(nilfs);
214 
215 		/* update GC protection for recent segments */
216 		if (nilfs->ns_sbh[1]) {
217 			if (flag == NILFS_SB_COMMIT_ALL) {
218 				set_buffer_dirty(nilfs->ns_sbh[1]);
219 				if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
220 					goto out;
221 			}
222 			if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
223 			    le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
224 				sbp = nilfs->ns_sbp[1];
225 		}
226 
227 		spin_lock(&nilfs->ns_last_segment_lock);
228 		nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
229 		spin_unlock(&nilfs->ns_last_segment_lock);
230 	}
231  out:
232 	return err;
233 }
234 
235 void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
236 			  struct the_nilfs *nilfs)
237 {
238 	sector_t nfreeblocks;
239 
240 	/* nilfs->ns_sem must be locked by the caller. */
241 	nilfs_count_free_blocks(nilfs, &nfreeblocks);
242 	sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
243 
244 	spin_lock(&nilfs->ns_last_segment_lock);
245 	sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
246 	sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
247 	sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
248 	spin_unlock(&nilfs->ns_last_segment_lock);
249 }
250 
251 struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
252 					       int flip)
253 {
254 	struct the_nilfs *nilfs = sb->s_fs_info;
255 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
256 
257 	/* nilfs->ns_sem must be locked by the caller. */
258 	if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
259 		if (sbp[1] &&
260 		    sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
261 			memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
262 		} else {
263 			nilfs_crit(sb, "superblock broke");
264 			return NULL;
265 		}
266 	} else if (sbp[1] &&
267 		   sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
268 		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
269 	}
270 
271 	if (flip && sbp[1])
272 		nilfs_swap_super_block(nilfs);
273 
274 	return sbp;
275 }
276 
277 int nilfs_commit_super(struct super_block *sb, int flag)
278 {
279 	struct the_nilfs *nilfs = sb->s_fs_info;
280 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
281 	time64_t t;
282 
283 	/* nilfs->ns_sem must be locked by the caller. */
284 	t = ktime_get_real_seconds();
285 	nilfs->ns_sbwtime = t;
286 	sbp[0]->s_wtime = cpu_to_le64(t);
287 	sbp[0]->s_sum = 0;
288 	sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
289 					     (unsigned char *)sbp[0],
290 					     nilfs->ns_sbsize));
291 	if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
292 		sbp[1]->s_wtime = sbp[0]->s_wtime;
293 		sbp[1]->s_sum = 0;
294 		sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
295 					    (unsigned char *)sbp[1],
296 					    nilfs->ns_sbsize));
297 	}
298 	clear_nilfs_sb_dirty(nilfs);
299 	nilfs->ns_flushed_device = 1;
300 	/* make sure store to ns_flushed_device cannot be reordered */
301 	smp_wmb();
302 	return nilfs_sync_super(sb, flag);
303 }
304 
305 /**
306  * nilfs_cleanup_super() - write filesystem state for cleanup
307  * @sb: super block instance to be unmounted or degraded to read-only
308  *
309  * This function restores state flags in the on-disk super block.
310  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
311  * filesystem was not clean previously.
312  */
313 int nilfs_cleanup_super(struct super_block *sb)
314 {
315 	struct the_nilfs *nilfs = sb->s_fs_info;
316 	struct nilfs_super_block **sbp;
317 	int flag = NILFS_SB_COMMIT;
318 	int ret = -EIO;
319 
320 	sbp = nilfs_prepare_super(sb, 0);
321 	if (sbp) {
322 		sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
323 		nilfs_set_log_cursor(sbp[0], nilfs);
324 		if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
325 			/*
326 			 * make the "clean" flag also to the opposite
327 			 * super block if both super blocks point to
328 			 * the same checkpoint.
329 			 */
330 			sbp[1]->s_state = sbp[0]->s_state;
331 			flag = NILFS_SB_COMMIT_ALL;
332 		}
333 		ret = nilfs_commit_super(sb, flag);
334 	}
335 	return ret;
336 }
337 
338 /**
339  * nilfs_move_2nd_super - relocate secondary super block
340  * @sb: super block instance
341  * @sb2off: new offset of the secondary super block (in bytes)
342  */
343 static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
344 {
345 	struct the_nilfs *nilfs = sb->s_fs_info;
346 	struct buffer_head *nsbh;
347 	struct nilfs_super_block *nsbp;
348 	sector_t blocknr, newblocknr;
349 	unsigned long offset;
350 	int sb2i;  /* array index of the secondary superblock */
351 	int ret = 0;
352 
353 	/* nilfs->ns_sem must be locked by the caller. */
354 	if (nilfs->ns_sbh[1] &&
355 	    nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
356 		sb2i = 1;
357 		blocknr = nilfs->ns_sbh[1]->b_blocknr;
358 	} else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
359 		sb2i = 0;
360 		blocknr = nilfs->ns_sbh[0]->b_blocknr;
361 	} else {
362 		sb2i = -1;
363 		blocknr = 0;
364 	}
365 	if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
366 		goto out;  /* super block location is unchanged */
367 
368 	/* Get new super block buffer */
369 	newblocknr = sb2off >> nilfs->ns_blocksize_bits;
370 	offset = sb2off & (nilfs->ns_blocksize - 1);
371 	nsbh = sb_getblk(sb, newblocknr);
372 	if (!nsbh) {
373 		nilfs_warn(sb,
374 			   "unable to move secondary superblock to block %llu",
375 			   (unsigned long long)newblocknr);
376 		ret = -EIO;
377 		goto out;
378 	}
379 	nsbp = (void *)nsbh->b_data + offset;
380 
381 	lock_buffer(nsbh);
382 	if (sb2i >= 0) {
383 		/*
384 		 * The position of the second superblock only changes by 4KiB,
385 		 * which is larger than the maximum superblock data size
386 		 * (= 1KiB), so there is no need to use memmove() to allow
387 		 * overlap between source and destination.
388 		 */
389 		memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
390 
391 		/*
392 		 * Zero fill after copy to avoid overwriting in case of move
393 		 * within the same block.
394 		 */
395 		memset(nsbh->b_data, 0, offset);
396 		memset((void *)nsbp + nilfs->ns_sbsize, 0,
397 		       nsbh->b_size - offset - nilfs->ns_sbsize);
398 	} else {
399 		memset(nsbh->b_data, 0, nsbh->b_size);
400 	}
401 	set_buffer_uptodate(nsbh);
402 	unlock_buffer(nsbh);
403 
404 	if (sb2i >= 0) {
405 		brelse(nilfs->ns_sbh[sb2i]);
406 		nilfs->ns_sbh[sb2i] = nsbh;
407 		nilfs->ns_sbp[sb2i] = nsbp;
408 	} else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
409 		/* secondary super block will be restored to index 1 */
410 		nilfs->ns_sbh[1] = nsbh;
411 		nilfs->ns_sbp[1] = nsbp;
412 	} else {
413 		brelse(nsbh);
414 	}
415 out:
416 	return ret;
417 }
418 
419 /**
420  * nilfs_resize_fs - resize the filesystem
421  * @sb: super block instance
422  * @newsize: new size of the filesystem (in bytes)
423  */
424 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
425 {
426 	struct the_nilfs *nilfs = sb->s_fs_info;
427 	struct nilfs_super_block **sbp;
428 	__u64 devsize, newnsegs;
429 	loff_t sb2off;
430 	int ret;
431 
432 	ret = -ERANGE;
433 	devsize = bdev_nr_bytes(sb->s_bdev);
434 	if (newsize > devsize)
435 		goto out;
436 
437 	/*
438 	 * Prevent underflow in second superblock position calculation.
439 	 * The exact minimum size check is done in nilfs_sufile_resize().
440 	 */
441 	if (newsize < 4096) {
442 		ret = -ENOSPC;
443 		goto out;
444 	}
445 
446 	/*
447 	 * Write lock is required to protect some functions depending
448 	 * on the number of segments, the number of reserved segments,
449 	 * and so forth.
450 	 */
451 	down_write(&nilfs->ns_segctor_sem);
452 
453 	sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
454 	newnsegs = sb2off >> nilfs->ns_blocksize_bits;
455 	newnsegs = div64_ul(newnsegs, nilfs->ns_blocks_per_segment);
456 
457 	ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
458 	up_write(&nilfs->ns_segctor_sem);
459 	if (ret < 0)
460 		goto out;
461 
462 	ret = nilfs_construct_segment(sb);
463 	if (ret < 0)
464 		goto out;
465 
466 	down_write(&nilfs->ns_sem);
467 	nilfs_move_2nd_super(sb, sb2off);
468 	ret = -EIO;
469 	sbp = nilfs_prepare_super(sb, 0);
470 	if (likely(sbp)) {
471 		nilfs_set_log_cursor(sbp[0], nilfs);
472 		/*
473 		 * Drop NILFS_RESIZE_FS flag for compatibility with
474 		 * mount-time resize which may be implemented in a
475 		 * future release.
476 		 */
477 		sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
478 					      ~NILFS_RESIZE_FS);
479 		sbp[0]->s_dev_size = cpu_to_le64(newsize);
480 		sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
481 		if (sbp[1])
482 			memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
483 		ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
484 	}
485 	up_write(&nilfs->ns_sem);
486 
487 	/*
488 	 * Reset the range of allocatable segments last.  This order
489 	 * is important in the case of expansion because the secondary
490 	 * superblock must be protected from log write until migration
491 	 * completes.
492 	 */
493 	if (!ret)
494 		nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
495 out:
496 	return ret;
497 }
498 
499 static void nilfs_put_super(struct super_block *sb)
500 {
501 	struct the_nilfs *nilfs = sb->s_fs_info;
502 
503 	nilfs_detach_log_writer(sb);
504 
505 	if (!sb_rdonly(sb)) {
506 		down_write(&nilfs->ns_sem);
507 		nilfs_cleanup_super(sb);
508 		up_write(&nilfs->ns_sem);
509 	}
510 
511 	nilfs_sysfs_delete_device_group(nilfs);
512 	iput(nilfs->ns_sufile);
513 	iput(nilfs->ns_cpfile);
514 	iput(nilfs->ns_dat);
515 
516 	destroy_nilfs(nilfs);
517 	sb->s_fs_info = NULL;
518 }
519 
520 static int nilfs_sync_fs(struct super_block *sb, int wait)
521 {
522 	struct the_nilfs *nilfs = sb->s_fs_info;
523 	struct nilfs_super_block **sbp;
524 	int err = 0;
525 
526 	/* This function is called when super block should be written back */
527 	if (wait)
528 		err = nilfs_construct_segment(sb);
529 
530 	down_write(&nilfs->ns_sem);
531 	if (nilfs_sb_dirty(nilfs)) {
532 		sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
533 		if (likely(sbp)) {
534 			nilfs_set_log_cursor(sbp[0], nilfs);
535 			nilfs_commit_super(sb, NILFS_SB_COMMIT);
536 		}
537 	}
538 	up_write(&nilfs->ns_sem);
539 
540 	if (!err)
541 		err = nilfs_flush_device(nilfs);
542 
543 	return err;
544 }
545 
546 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
547 			    struct nilfs_root **rootp)
548 {
549 	struct the_nilfs *nilfs = sb->s_fs_info;
550 	struct nilfs_root *root;
551 	int err = -ENOMEM;
552 
553 	root = nilfs_find_or_create_root(
554 		nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
555 	if (!root)
556 		return err;
557 
558 	if (root->ifile)
559 		goto reuse; /* already attached checkpoint */
560 
561 	down_read(&nilfs->ns_segctor_sem);
562 	err = nilfs_ifile_read(sb, root, cno, nilfs->ns_inode_size);
563 	up_read(&nilfs->ns_segctor_sem);
564 	if (unlikely(err))
565 		goto failed;
566 
567  reuse:
568 	*rootp = root;
569 	return 0;
570 
571  failed:
572 	if (err == -EINVAL)
573 		nilfs_err(sb, "Invalid checkpoint (checkpoint number=%llu)",
574 			  (unsigned long long)cno);
575 	nilfs_put_root(root);
576 
577 	return err;
578 }
579 
580 static int nilfs_freeze(struct super_block *sb)
581 {
582 	struct the_nilfs *nilfs = sb->s_fs_info;
583 	int err;
584 
585 	if (sb_rdonly(sb))
586 		return 0;
587 
588 	/* Mark super block clean */
589 	down_write(&nilfs->ns_sem);
590 	err = nilfs_cleanup_super(sb);
591 	up_write(&nilfs->ns_sem);
592 	return err;
593 }
594 
595 static int nilfs_unfreeze(struct super_block *sb)
596 {
597 	struct the_nilfs *nilfs = sb->s_fs_info;
598 
599 	if (sb_rdonly(sb))
600 		return 0;
601 
602 	down_write(&nilfs->ns_sem);
603 	nilfs_setup_super(sb, false);
604 	up_write(&nilfs->ns_sem);
605 	return 0;
606 }
607 
608 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
609 {
610 	struct super_block *sb = dentry->d_sb;
611 	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
612 	struct the_nilfs *nilfs = root->nilfs;
613 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
614 	unsigned long long blocks;
615 	unsigned long overhead;
616 	unsigned long nrsvblocks;
617 	sector_t nfreeblocks;
618 	u64 nmaxinodes, nfreeinodes;
619 	int err;
620 
621 	/*
622 	 * Compute all of the segment blocks
623 	 *
624 	 * The blocks before first segment and after last segment
625 	 * are excluded.
626 	 */
627 	blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
628 		- nilfs->ns_first_data_block;
629 	nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
630 
631 	/*
632 	 * Compute the overhead
633 	 *
634 	 * When distributing meta data blocks outside segment structure,
635 	 * We must count them as the overhead.
636 	 */
637 	overhead = 0;
638 
639 	err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
640 	if (unlikely(err))
641 		return err;
642 
643 	err = nilfs_ifile_count_free_inodes(root->ifile,
644 					    &nmaxinodes, &nfreeinodes);
645 	if (unlikely(err)) {
646 		nilfs_warn(sb, "failed to count free inodes: err=%d", err);
647 		if (err == -ERANGE) {
648 			/*
649 			 * If nilfs_palloc_count_max_entries() returns
650 			 * -ERANGE error code then we simply treat
651 			 * curent inodes count as maximum possible and
652 			 * zero as free inodes value.
653 			 */
654 			nmaxinodes = atomic64_read(&root->inodes_count);
655 			nfreeinodes = 0;
656 			err = 0;
657 		} else
658 			return err;
659 	}
660 
661 	buf->f_type = NILFS_SUPER_MAGIC;
662 	buf->f_bsize = sb->s_blocksize;
663 	buf->f_blocks = blocks - overhead;
664 	buf->f_bfree = nfreeblocks;
665 	buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
666 		(buf->f_bfree - nrsvblocks) : 0;
667 	buf->f_files = nmaxinodes;
668 	buf->f_ffree = nfreeinodes;
669 	buf->f_namelen = NILFS_NAME_LEN;
670 	buf->f_fsid = u64_to_fsid(id);
671 
672 	return 0;
673 }
674 
675 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
676 {
677 	struct super_block *sb = dentry->d_sb;
678 	struct the_nilfs *nilfs = sb->s_fs_info;
679 	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
680 
681 	if (!nilfs_test_opt(nilfs, BARRIER))
682 		seq_puts(seq, ",nobarrier");
683 	if (root->cno != NILFS_CPTREE_CURRENT_CNO)
684 		seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
685 	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
686 		seq_puts(seq, ",errors=panic");
687 	if (nilfs_test_opt(nilfs, ERRORS_CONT))
688 		seq_puts(seq, ",errors=continue");
689 	if (nilfs_test_opt(nilfs, STRICT_ORDER))
690 		seq_puts(seq, ",order=strict");
691 	if (nilfs_test_opt(nilfs, NORECOVERY))
692 		seq_puts(seq, ",norecovery");
693 	if (nilfs_test_opt(nilfs, DISCARD))
694 		seq_puts(seq, ",discard");
695 
696 	return 0;
697 }
698 
699 static const struct super_operations nilfs_sops = {
700 	.alloc_inode    = nilfs_alloc_inode,
701 	.free_inode     = nilfs_free_inode,
702 	.dirty_inode    = nilfs_dirty_inode,
703 	.evict_inode    = nilfs_evict_inode,
704 	.put_super      = nilfs_put_super,
705 	.sync_fs        = nilfs_sync_fs,
706 	.freeze_fs	= nilfs_freeze,
707 	.unfreeze_fs	= nilfs_unfreeze,
708 	.statfs         = nilfs_statfs,
709 	.show_options = nilfs_show_options
710 };
711 
712 enum {
713 	Opt_err, Opt_barrier, Opt_snapshot, Opt_order, Opt_norecovery,
714 	Opt_discard,
715 };
716 
717 static const struct constant_table nilfs_param_err[] = {
718 	{"continue",	NILFS_MOUNT_ERRORS_CONT},
719 	{"panic",	NILFS_MOUNT_ERRORS_PANIC},
720 	{"remount-ro",	NILFS_MOUNT_ERRORS_RO},
721 	{}
722 };
723 
724 static const struct fs_parameter_spec nilfs_param_spec[] = {
725 	fsparam_enum	("errors", Opt_err, nilfs_param_err),
726 	fsparam_flag_no	("barrier", Opt_barrier),
727 	fsparam_u64	("cp", Opt_snapshot),
728 	fsparam_string	("order", Opt_order),
729 	fsparam_flag	("norecovery", Opt_norecovery),
730 	fsparam_flag_no	("discard", Opt_discard),
731 	{}
732 };
733 
734 struct nilfs_fs_context {
735 	unsigned long ns_mount_opt;
736 	__u64 cno;
737 };
738 
739 static int nilfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
740 {
741 	struct nilfs_fs_context *nilfs = fc->fs_private;
742 	int is_remount = fc->purpose == FS_CONTEXT_FOR_RECONFIGURE;
743 	struct fs_parse_result result;
744 	int opt;
745 
746 	opt = fs_parse(fc, nilfs_param_spec, param, &result);
747 	if (opt < 0)
748 		return opt;
749 
750 	switch (opt) {
751 	case Opt_barrier:
752 		if (result.negated)
753 			nilfs_clear_opt(nilfs, BARRIER);
754 		else
755 			nilfs_set_opt(nilfs, BARRIER);
756 		break;
757 	case Opt_order:
758 		if (strcmp(param->string, "relaxed") == 0)
759 			/* Ordered data semantics */
760 			nilfs_clear_opt(nilfs, STRICT_ORDER);
761 		else if (strcmp(param->string, "strict") == 0)
762 			/* Strict in-order semantics */
763 			nilfs_set_opt(nilfs, STRICT_ORDER);
764 		else
765 			return -EINVAL;
766 		break;
767 	case Opt_err:
768 		nilfs->ns_mount_opt &= ~NILFS_MOUNT_ERROR_MODE;
769 		nilfs->ns_mount_opt |= result.uint_32;
770 		break;
771 	case Opt_snapshot:
772 		if (is_remount) {
773 			struct super_block *sb = fc->root->d_sb;
774 
775 			nilfs_err(sb,
776 				  "\"%s\" option is invalid for remount",
777 				  param->key);
778 			return -EINVAL;
779 		}
780 		if (result.uint_64 == 0) {
781 			nilfs_err(NULL,
782 				  "invalid option \"cp=0\": invalid checkpoint number 0");
783 			return -EINVAL;
784 		}
785 		nilfs->cno = result.uint_64;
786 		break;
787 	case Opt_norecovery:
788 		nilfs_set_opt(nilfs, NORECOVERY);
789 		break;
790 	case Opt_discard:
791 		if (result.negated)
792 			nilfs_clear_opt(nilfs, DISCARD);
793 		else
794 			nilfs_set_opt(nilfs, DISCARD);
795 		break;
796 	default:
797 		return -EINVAL;
798 	}
799 
800 	return 0;
801 }
802 
803 static int nilfs_setup_super(struct super_block *sb, int is_mount)
804 {
805 	struct the_nilfs *nilfs = sb->s_fs_info;
806 	struct nilfs_super_block **sbp;
807 	int max_mnt_count;
808 	int mnt_count;
809 
810 	/* nilfs->ns_sem must be locked by the caller. */
811 	sbp = nilfs_prepare_super(sb, 0);
812 	if (!sbp)
813 		return -EIO;
814 
815 	if (!is_mount)
816 		goto skip_mount_setup;
817 
818 	max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
819 	mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
820 
821 	if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
822 		nilfs_warn(sb, "mounting fs with errors");
823 #if 0
824 	} else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
825 		nilfs_warn(sb, "maximal mount count reached");
826 #endif
827 	}
828 	if (!max_mnt_count)
829 		sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
830 
831 	sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
832 	sbp[0]->s_mtime = cpu_to_le64(ktime_get_real_seconds());
833 
834 skip_mount_setup:
835 	sbp[0]->s_state =
836 		cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
837 	/* synchronize sbp[1] with sbp[0] */
838 	if (sbp[1])
839 		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
840 	return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
841 }
842 
843 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
844 						 u64 pos, int blocksize,
845 						 struct buffer_head **pbh)
846 {
847 	unsigned long long sb_index = pos;
848 	unsigned long offset;
849 
850 	offset = do_div(sb_index, blocksize);
851 	*pbh = sb_bread(sb, sb_index);
852 	if (!*pbh)
853 		return NULL;
854 	return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
855 }
856 
857 int nilfs_store_magic(struct super_block *sb,
858 		      struct nilfs_super_block *sbp)
859 {
860 	struct the_nilfs *nilfs = sb->s_fs_info;
861 
862 	sb->s_magic = le16_to_cpu(sbp->s_magic);
863 
864 	/* FS independent flags */
865 #ifdef NILFS_ATIME_DISABLE
866 	sb->s_flags |= SB_NOATIME;
867 #endif
868 
869 	nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
870 	nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
871 	nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
872 	nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
873 
874 	return 0;
875 }
876 
877 int nilfs_check_feature_compatibility(struct super_block *sb,
878 				      struct nilfs_super_block *sbp)
879 {
880 	__u64 features;
881 
882 	features = le64_to_cpu(sbp->s_feature_incompat) &
883 		~NILFS_FEATURE_INCOMPAT_SUPP;
884 	if (features) {
885 		nilfs_err(sb,
886 			  "couldn't mount because of unsupported optional features (%llx)",
887 			  (unsigned long long)features);
888 		return -EINVAL;
889 	}
890 	features = le64_to_cpu(sbp->s_feature_compat_ro) &
891 		~NILFS_FEATURE_COMPAT_RO_SUPP;
892 	if (!sb_rdonly(sb) && features) {
893 		nilfs_err(sb,
894 			  "couldn't mount RDWR because of unsupported optional features (%llx)",
895 			  (unsigned long long)features);
896 		return -EINVAL;
897 	}
898 	return 0;
899 }
900 
901 static int nilfs_get_root_dentry(struct super_block *sb,
902 				 struct nilfs_root *root,
903 				 struct dentry **root_dentry)
904 {
905 	struct inode *inode;
906 	struct dentry *dentry;
907 	int ret = 0;
908 
909 	inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
910 	if (IS_ERR(inode)) {
911 		ret = PTR_ERR(inode);
912 		nilfs_err(sb, "error %d getting root inode", ret);
913 		goto out;
914 	}
915 	if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
916 		iput(inode);
917 		nilfs_err(sb, "corrupt root inode");
918 		ret = -EINVAL;
919 		goto out;
920 	}
921 
922 	if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
923 		dentry = d_find_alias(inode);
924 		if (!dentry) {
925 			dentry = d_make_root(inode);
926 			if (!dentry) {
927 				ret = -ENOMEM;
928 				goto failed_dentry;
929 			}
930 		} else {
931 			iput(inode);
932 		}
933 	} else {
934 		dentry = d_obtain_root(inode);
935 		if (IS_ERR(dentry)) {
936 			ret = PTR_ERR(dentry);
937 			goto failed_dentry;
938 		}
939 	}
940 	*root_dentry = dentry;
941  out:
942 	return ret;
943 
944  failed_dentry:
945 	nilfs_err(sb, "error %d getting root dentry", ret);
946 	goto out;
947 }
948 
949 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
950 				 struct dentry **root_dentry)
951 {
952 	struct the_nilfs *nilfs = s->s_fs_info;
953 	struct nilfs_root *root;
954 	int ret;
955 
956 	mutex_lock(&nilfs->ns_snapshot_mount_mutex);
957 
958 	down_read(&nilfs->ns_segctor_sem);
959 	ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
960 	up_read(&nilfs->ns_segctor_sem);
961 	if (ret < 0) {
962 		ret = (ret == -ENOENT) ? -EINVAL : ret;
963 		goto out;
964 	} else if (!ret) {
965 		nilfs_err(s,
966 			  "The specified checkpoint is not a snapshot (checkpoint number=%llu)",
967 			  (unsigned long long)cno);
968 		ret = -EINVAL;
969 		goto out;
970 	}
971 
972 	ret = nilfs_attach_checkpoint(s, cno, false, &root);
973 	if (ret) {
974 		nilfs_err(s,
975 			  "error %d while loading snapshot (checkpoint number=%llu)",
976 			  ret, (unsigned long long)cno);
977 		goto out;
978 	}
979 	ret = nilfs_get_root_dentry(s, root, root_dentry);
980 	nilfs_put_root(root);
981  out:
982 	mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
983 	return ret;
984 }
985 
986 /**
987  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
988  * @root_dentry: root dentry of the tree to be shrunk
989  *
990  * This function returns true if the tree was in-use.
991  */
992 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
993 {
994 	shrink_dcache_parent(root_dentry);
995 	return d_count(root_dentry) > 1;
996 }
997 
998 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
999 {
1000 	struct the_nilfs *nilfs = sb->s_fs_info;
1001 	struct nilfs_root *root;
1002 	struct inode *inode;
1003 	struct dentry *dentry;
1004 	int ret;
1005 
1006 	if (cno > nilfs->ns_cno)
1007 		return false;
1008 
1009 	if (cno >= nilfs_last_cno(nilfs))
1010 		return true;	/* protect recent checkpoints */
1011 
1012 	ret = false;
1013 	root = nilfs_lookup_root(nilfs, cno);
1014 	if (root) {
1015 		inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1016 		if (inode) {
1017 			dentry = d_find_alias(inode);
1018 			if (dentry) {
1019 				ret = nilfs_tree_is_busy(dentry);
1020 				dput(dentry);
1021 			}
1022 			iput(inode);
1023 		}
1024 		nilfs_put_root(root);
1025 	}
1026 	return ret;
1027 }
1028 
1029 /**
1030  * nilfs_fill_super() - initialize a super block instance
1031  * @sb: super_block
1032  * @fc: filesystem context
1033  *
1034  * This function is called exclusively by nilfs->ns_mount_mutex.
1035  * So, the recovery process is protected from other simultaneous mounts.
1036  */
1037 static int
1038 nilfs_fill_super(struct super_block *sb, struct fs_context *fc)
1039 {
1040 	struct the_nilfs *nilfs;
1041 	struct nilfs_root *fsroot;
1042 	struct nilfs_fs_context *ctx = fc->fs_private;
1043 	__u64 cno;
1044 	int err;
1045 
1046 	nilfs = alloc_nilfs(sb);
1047 	if (!nilfs)
1048 		return -ENOMEM;
1049 
1050 	sb->s_fs_info = nilfs;
1051 
1052 	err = init_nilfs(nilfs, sb);
1053 	if (err)
1054 		goto failed_nilfs;
1055 
1056 	/* Copy in parsed mount options */
1057 	nilfs->ns_mount_opt = ctx->ns_mount_opt;
1058 
1059 	sb->s_op = &nilfs_sops;
1060 	sb->s_export_op = &nilfs_export_ops;
1061 	sb->s_root = NULL;
1062 	sb->s_time_gran = 1;
1063 	sb->s_max_links = NILFS_LINK_MAX;
1064 
1065 	sb->s_bdi = bdi_get(sb->s_bdev->bd_disk->bdi);
1066 
1067 	err = load_nilfs(nilfs, sb);
1068 	if (err)
1069 		goto failed_nilfs;
1070 
1071 	super_set_uuid(sb, nilfs->ns_sbp[0]->s_uuid,
1072 		       sizeof(nilfs->ns_sbp[0]->s_uuid));
1073 	super_set_sysfs_name_bdev(sb);
1074 
1075 	cno = nilfs_last_cno(nilfs);
1076 	err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1077 	if (err) {
1078 		nilfs_err(sb,
1079 			  "error %d while loading last checkpoint (checkpoint number=%llu)",
1080 			  err, (unsigned long long)cno);
1081 		goto failed_unload;
1082 	}
1083 
1084 	if (!sb_rdonly(sb)) {
1085 		err = nilfs_attach_log_writer(sb, fsroot);
1086 		if (err)
1087 			goto failed_checkpoint;
1088 	}
1089 
1090 	err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1091 	if (err)
1092 		goto failed_segctor;
1093 
1094 	nilfs_put_root(fsroot);
1095 
1096 	if (!sb_rdonly(sb)) {
1097 		down_write(&nilfs->ns_sem);
1098 		nilfs_setup_super(sb, true);
1099 		up_write(&nilfs->ns_sem);
1100 	}
1101 
1102 	return 0;
1103 
1104  failed_segctor:
1105 	nilfs_detach_log_writer(sb);
1106 
1107  failed_checkpoint:
1108 	nilfs_put_root(fsroot);
1109 
1110  failed_unload:
1111 	nilfs_sysfs_delete_device_group(nilfs);
1112 	iput(nilfs->ns_sufile);
1113 	iput(nilfs->ns_cpfile);
1114 	iput(nilfs->ns_dat);
1115 
1116  failed_nilfs:
1117 	destroy_nilfs(nilfs);
1118 	return err;
1119 }
1120 
1121 static int nilfs_reconfigure(struct fs_context *fc)
1122 {
1123 	struct nilfs_fs_context *ctx = fc->fs_private;
1124 	struct super_block *sb = fc->root->d_sb;
1125 	struct the_nilfs *nilfs = sb->s_fs_info;
1126 	int err;
1127 
1128 	sync_filesystem(sb);
1129 
1130 	err = -EINVAL;
1131 
1132 	if (!nilfs_valid_fs(nilfs)) {
1133 		nilfs_warn(sb,
1134 			   "couldn't remount because the filesystem is in an incomplete recovery state");
1135 		goto ignore_opts;
1136 	}
1137 	if ((bool)(fc->sb_flags & SB_RDONLY) == sb_rdonly(sb))
1138 		goto out;
1139 	if (fc->sb_flags & SB_RDONLY) {
1140 		sb->s_flags |= SB_RDONLY;
1141 
1142 		/*
1143 		 * Remounting a valid RW partition RDONLY, so set
1144 		 * the RDONLY flag and then mark the partition as valid again.
1145 		 */
1146 		down_write(&nilfs->ns_sem);
1147 		nilfs_cleanup_super(sb);
1148 		up_write(&nilfs->ns_sem);
1149 	} else {
1150 		__u64 features;
1151 		struct nilfs_root *root;
1152 
1153 		/*
1154 		 * Mounting a RDONLY partition read-write, so reread and
1155 		 * store the current valid flag.  (It may have been changed
1156 		 * by fsck since we originally mounted the partition.)
1157 		 */
1158 		down_read(&nilfs->ns_sem);
1159 		features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1160 			~NILFS_FEATURE_COMPAT_RO_SUPP;
1161 		up_read(&nilfs->ns_sem);
1162 		if (features) {
1163 			nilfs_warn(sb,
1164 				   "couldn't remount RDWR because of unsupported optional features (%llx)",
1165 				   (unsigned long long)features);
1166 			err = -EROFS;
1167 			goto ignore_opts;
1168 		}
1169 
1170 		sb->s_flags &= ~SB_RDONLY;
1171 
1172 		root = NILFS_I(d_inode(sb->s_root))->i_root;
1173 		err = nilfs_attach_log_writer(sb, root);
1174 		if (err) {
1175 			sb->s_flags |= SB_RDONLY;
1176 			goto ignore_opts;
1177 		}
1178 
1179 		down_write(&nilfs->ns_sem);
1180 		nilfs_setup_super(sb, true);
1181 		up_write(&nilfs->ns_sem);
1182 	}
1183  out:
1184 	sb->s_flags = (sb->s_flags & ~SB_POSIXACL);
1185 	/* Copy over parsed remount options */
1186 	nilfs->ns_mount_opt = ctx->ns_mount_opt;
1187 
1188 	return 0;
1189 
1190  ignore_opts:
1191 	return err;
1192 }
1193 
1194 static int
1195 nilfs_get_tree(struct fs_context *fc)
1196 {
1197 	struct nilfs_fs_context *ctx = fc->fs_private;
1198 	struct super_block *s;
1199 	dev_t dev;
1200 	int err;
1201 
1202 	if (ctx->cno && !(fc->sb_flags & SB_RDONLY)) {
1203 		nilfs_err(NULL,
1204 			  "invalid option \"cp=%llu\": read-only option is not specified",
1205 			  ctx->cno);
1206 		return -EINVAL;
1207 	}
1208 
1209 	err = lookup_bdev(fc->source, &dev);
1210 	if (err)
1211 		return err;
1212 
1213 	s = sget_dev(fc, dev);
1214 	if (IS_ERR(s))
1215 		return PTR_ERR(s);
1216 
1217 	if (!s->s_root) {
1218 		err = setup_bdev_super(s, fc->sb_flags, fc);
1219 		if (!err)
1220 			err = nilfs_fill_super(s, fc);
1221 		if (err)
1222 			goto failed_super;
1223 
1224 		s->s_flags |= SB_ACTIVE;
1225 	} else if (!ctx->cno) {
1226 		if (nilfs_tree_is_busy(s->s_root)) {
1227 			if ((fc->sb_flags ^ s->s_flags) & SB_RDONLY) {
1228 				nilfs_err(s,
1229 					  "the device already has a %s mount.",
1230 					  sb_rdonly(s) ? "read-only" : "read/write");
1231 				err = -EBUSY;
1232 				goto failed_super;
1233 			}
1234 		} else {
1235 			/*
1236 			 * Try reconfigure to setup mount states if the current
1237 			 * tree is not mounted and only snapshots use this sb.
1238 			 *
1239 			 * Since nilfs_reconfigure() requires fc->root to be
1240 			 * set, set it first and release it on failure.
1241 			 */
1242 			fc->root = dget(s->s_root);
1243 			err = nilfs_reconfigure(fc);
1244 			if (err) {
1245 				dput(fc->root);
1246 				fc->root = NULL;  /* prevent double release */
1247 				goto failed_super;
1248 			}
1249 			return 0;
1250 		}
1251 	}
1252 
1253 	if (ctx->cno) {
1254 		struct dentry *root_dentry;
1255 
1256 		err = nilfs_attach_snapshot(s, ctx->cno, &root_dentry);
1257 		if (err)
1258 			goto failed_super;
1259 		fc->root = root_dentry;
1260 		return 0;
1261 	}
1262 
1263 	fc->root = dget(s->s_root);
1264 	return 0;
1265 
1266  failed_super:
1267 	deactivate_locked_super(s);
1268 	return err;
1269 }
1270 
1271 static void nilfs_free_fc(struct fs_context *fc)
1272 {
1273 	kfree(fc->fs_private);
1274 }
1275 
1276 static const struct fs_context_operations nilfs_context_ops = {
1277 	.parse_param	= nilfs_parse_param,
1278 	.get_tree	= nilfs_get_tree,
1279 	.reconfigure	= nilfs_reconfigure,
1280 	.free		= nilfs_free_fc,
1281 };
1282 
1283 static int nilfs_init_fs_context(struct fs_context *fc)
1284 {
1285 	struct nilfs_fs_context *ctx;
1286 
1287 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
1288 	if (!ctx)
1289 		return -ENOMEM;
1290 
1291 	ctx->ns_mount_opt = NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
1292 	fc->fs_private = ctx;
1293 	fc->ops = &nilfs_context_ops;
1294 
1295 	return 0;
1296 }
1297 
1298 struct file_system_type nilfs_fs_type = {
1299 	.owner    = THIS_MODULE,
1300 	.name     = "nilfs2",
1301 	.kill_sb  = kill_block_super,
1302 	.fs_flags = FS_REQUIRES_DEV,
1303 	.init_fs_context = nilfs_init_fs_context,
1304 	.parameters = nilfs_param_spec,
1305 };
1306 MODULE_ALIAS_FS("nilfs2");
1307 
1308 static void nilfs_inode_init_once(void *obj)
1309 {
1310 	struct nilfs_inode_info *ii = obj;
1311 
1312 	INIT_LIST_HEAD(&ii->i_dirty);
1313 #ifdef CONFIG_NILFS_XATTR
1314 	init_rwsem(&ii->xattr_sem);
1315 #endif
1316 	inode_init_once(&ii->vfs_inode);
1317 }
1318 
1319 static void nilfs_segbuf_init_once(void *obj)
1320 {
1321 	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1322 }
1323 
1324 static void nilfs_destroy_cachep(void)
1325 {
1326 	/*
1327 	 * Make sure all delayed rcu free inodes are flushed before we
1328 	 * destroy cache.
1329 	 */
1330 	rcu_barrier();
1331 
1332 	kmem_cache_destroy(nilfs_inode_cachep);
1333 	kmem_cache_destroy(nilfs_transaction_cachep);
1334 	kmem_cache_destroy(nilfs_segbuf_cachep);
1335 	kmem_cache_destroy(nilfs_btree_path_cache);
1336 }
1337 
1338 static int __init nilfs_init_cachep(void)
1339 {
1340 	nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1341 			sizeof(struct nilfs_inode_info), 0,
1342 			SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
1343 			nilfs_inode_init_once);
1344 	if (!nilfs_inode_cachep)
1345 		goto fail;
1346 
1347 	nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1348 			sizeof(struct nilfs_transaction_info), 0,
1349 			SLAB_RECLAIM_ACCOUNT, NULL);
1350 	if (!nilfs_transaction_cachep)
1351 		goto fail;
1352 
1353 	nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1354 			sizeof(struct nilfs_segment_buffer), 0,
1355 			SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1356 	if (!nilfs_segbuf_cachep)
1357 		goto fail;
1358 
1359 	nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1360 			sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1361 			0, 0, NULL);
1362 	if (!nilfs_btree_path_cache)
1363 		goto fail;
1364 
1365 	return 0;
1366 
1367 fail:
1368 	nilfs_destroy_cachep();
1369 	return -ENOMEM;
1370 }
1371 
1372 static int __init init_nilfs_fs(void)
1373 {
1374 	int err;
1375 
1376 	err = nilfs_init_cachep();
1377 	if (err)
1378 		goto fail;
1379 
1380 	err = nilfs_sysfs_init();
1381 	if (err)
1382 		goto free_cachep;
1383 
1384 	err = register_filesystem(&nilfs_fs_type);
1385 	if (err)
1386 		goto deinit_sysfs_entry;
1387 
1388 	printk(KERN_INFO "NILFS version 2 loaded\n");
1389 	return 0;
1390 
1391 deinit_sysfs_entry:
1392 	nilfs_sysfs_exit();
1393 free_cachep:
1394 	nilfs_destroy_cachep();
1395 fail:
1396 	return err;
1397 }
1398 
1399 static void __exit exit_nilfs_fs(void)
1400 {
1401 	nilfs_destroy_cachep();
1402 	nilfs_sysfs_exit();
1403 	unregister_filesystem(&nilfs_fs_type);
1404 }
1405 
1406 module_init(init_nilfs_fs)
1407 module_exit(exit_nilfs_fs)
1408