xref: /linux/fs/nilfs2/super.c (revision fdd51b3e73e906aac056f2c337710185607d43d1)
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 	newnsegs = div64_ul(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 	int err = -ENOMEM;
548 
549 	root = nilfs_find_or_create_root(
550 		nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
551 	if (!root)
552 		return err;
553 
554 	if (root->ifile)
555 		goto reuse; /* already attached checkpoint */
556 
557 	down_read(&nilfs->ns_segctor_sem);
558 	err = nilfs_ifile_read(sb, root, cno, nilfs->ns_inode_size);
559 	up_read(&nilfs->ns_segctor_sem);
560 	if (unlikely(err))
561 		goto failed;
562 
563  reuse:
564 	*rootp = root;
565 	return 0;
566 
567  failed:
568 	if (err == -EINVAL)
569 		nilfs_err(sb, "Invalid checkpoint (checkpoint number=%llu)",
570 			  (unsigned long long)cno);
571 	nilfs_put_root(root);
572 
573 	return err;
574 }
575 
576 static int nilfs_freeze(struct super_block *sb)
577 {
578 	struct the_nilfs *nilfs = sb->s_fs_info;
579 	int err;
580 
581 	if (sb_rdonly(sb))
582 		return 0;
583 
584 	/* Mark super block clean */
585 	down_write(&nilfs->ns_sem);
586 	err = nilfs_cleanup_super(sb);
587 	up_write(&nilfs->ns_sem);
588 	return err;
589 }
590 
591 static int nilfs_unfreeze(struct super_block *sb)
592 {
593 	struct the_nilfs *nilfs = sb->s_fs_info;
594 
595 	if (sb_rdonly(sb))
596 		return 0;
597 
598 	down_write(&nilfs->ns_sem);
599 	nilfs_setup_super(sb, false);
600 	up_write(&nilfs->ns_sem);
601 	return 0;
602 }
603 
604 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
605 {
606 	struct super_block *sb = dentry->d_sb;
607 	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
608 	struct the_nilfs *nilfs = root->nilfs;
609 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
610 	unsigned long long blocks;
611 	unsigned long overhead;
612 	unsigned long nrsvblocks;
613 	sector_t nfreeblocks;
614 	u64 nmaxinodes, nfreeinodes;
615 	int err;
616 
617 	/*
618 	 * Compute all of the segment blocks
619 	 *
620 	 * The blocks before first segment and after last segment
621 	 * are excluded.
622 	 */
623 	blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
624 		- nilfs->ns_first_data_block;
625 	nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
626 
627 	/*
628 	 * Compute the overhead
629 	 *
630 	 * When distributing meta data blocks outside segment structure,
631 	 * We must count them as the overhead.
632 	 */
633 	overhead = 0;
634 
635 	err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
636 	if (unlikely(err))
637 		return err;
638 
639 	err = nilfs_ifile_count_free_inodes(root->ifile,
640 					    &nmaxinodes, &nfreeinodes);
641 	if (unlikely(err)) {
642 		nilfs_warn(sb, "failed to count free inodes: err=%d", err);
643 		if (err == -ERANGE) {
644 			/*
645 			 * If nilfs_palloc_count_max_entries() returns
646 			 * -ERANGE error code then we simply treat
647 			 * curent inodes count as maximum possible and
648 			 * zero as free inodes value.
649 			 */
650 			nmaxinodes = atomic64_read(&root->inodes_count);
651 			nfreeinodes = 0;
652 			err = 0;
653 		} else
654 			return err;
655 	}
656 
657 	buf->f_type = NILFS_SUPER_MAGIC;
658 	buf->f_bsize = sb->s_blocksize;
659 	buf->f_blocks = blocks - overhead;
660 	buf->f_bfree = nfreeblocks;
661 	buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
662 		(buf->f_bfree - nrsvblocks) : 0;
663 	buf->f_files = nmaxinodes;
664 	buf->f_ffree = nfreeinodes;
665 	buf->f_namelen = NILFS_NAME_LEN;
666 	buf->f_fsid = u64_to_fsid(id);
667 
668 	return 0;
669 }
670 
671 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
672 {
673 	struct super_block *sb = dentry->d_sb;
674 	struct the_nilfs *nilfs = sb->s_fs_info;
675 	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
676 
677 	if (!nilfs_test_opt(nilfs, BARRIER))
678 		seq_puts(seq, ",nobarrier");
679 	if (root->cno != NILFS_CPTREE_CURRENT_CNO)
680 		seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
681 	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
682 		seq_puts(seq, ",errors=panic");
683 	if (nilfs_test_opt(nilfs, ERRORS_CONT))
684 		seq_puts(seq, ",errors=continue");
685 	if (nilfs_test_opt(nilfs, STRICT_ORDER))
686 		seq_puts(seq, ",order=strict");
687 	if (nilfs_test_opt(nilfs, NORECOVERY))
688 		seq_puts(seq, ",norecovery");
689 	if (nilfs_test_opt(nilfs, DISCARD))
690 		seq_puts(seq, ",discard");
691 
692 	return 0;
693 }
694 
695 static const struct super_operations nilfs_sops = {
696 	.alloc_inode    = nilfs_alloc_inode,
697 	.free_inode     = nilfs_free_inode,
698 	.dirty_inode    = nilfs_dirty_inode,
699 	.evict_inode    = nilfs_evict_inode,
700 	.put_super      = nilfs_put_super,
701 	.sync_fs        = nilfs_sync_fs,
702 	.freeze_fs	= nilfs_freeze,
703 	.unfreeze_fs	= nilfs_unfreeze,
704 	.statfs         = nilfs_statfs,
705 	.remount_fs     = nilfs_remount,
706 	.show_options = nilfs_show_options
707 };
708 
709 enum {
710 	Opt_err_cont, Opt_err_panic, Opt_err_ro,
711 	Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
712 	Opt_discard, Opt_nodiscard, Opt_err,
713 };
714 
715 static match_table_t tokens = {
716 	{Opt_err_cont, "errors=continue"},
717 	{Opt_err_panic, "errors=panic"},
718 	{Opt_err_ro, "errors=remount-ro"},
719 	{Opt_barrier, "barrier"},
720 	{Opt_nobarrier, "nobarrier"},
721 	{Opt_snapshot, "cp=%u"},
722 	{Opt_order, "order=%s"},
723 	{Opt_norecovery, "norecovery"},
724 	{Opt_discard, "discard"},
725 	{Opt_nodiscard, "nodiscard"},
726 	{Opt_err, NULL}
727 };
728 
729 static int parse_options(char *options, struct super_block *sb, int is_remount)
730 {
731 	struct the_nilfs *nilfs = sb->s_fs_info;
732 	char *p;
733 	substring_t args[MAX_OPT_ARGS];
734 
735 	if (!options)
736 		return 1;
737 
738 	while ((p = strsep(&options, ",")) != NULL) {
739 		int token;
740 
741 		if (!*p)
742 			continue;
743 
744 		token = match_token(p, tokens, args);
745 		switch (token) {
746 		case Opt_barrier:
747 			nilfs_set_opt(nilfs, BARRIER);
748 			break;
749 		case Opt_nobarrier:
750 			nilfs_clear_opt(nilfs, BARRIER);
751 			break;
752 		case Opt_order:
753 			if (strcmp(args[0].from, "relaxed") == 0)
754 				/* Ordered data semantics */
755 				nilfs_clear_opt(nilfs, STRICT_ORDER);
756 			else if (strcmp(args[0].from, "strict") == 0)
757 				/* Strict in-order semantics */
758 				nilfs_set_opt(nilfs, STRICT_ORDER);
759 			else
760 				return 0;
761 			break;
762 		case Opt_err_panic:
763 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
764 			break;
765 		case Opt_err_ro:
766 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
767 			break;
768 		case Opt_err_cont:
769 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
770 			break;
771 		case Opt_snapshot:
772 			if (is_remount) {
773 				nilfs_err(sb,
774 					  "\"%s\" option is invalid for remount",
775 					  p);
776 				return 0;
777 			}
778 			break;
779 		case Opt_norecovery:
780 			nilfs_set_opt(nilfs, NORECOVERY);
781 			break;
782 		case Opt_discard:
783 			nilfs_set_opt(nilfs, DISCARD);
784 			break;
785 		case Opt_nodiscard:
786 			nilfs_clear_opt(nilfs, DISCARD);
787 			break;
788 		default:
789 			nilfs_err(sb, "unrecognized mount option \"%s\"", p);
790 			return 0;
791 		}
792 	}
793 	return 1;
794 }
795 
796 static inline void
797 nilfs_set_default_options(struct super_block *sb,
798 			  struct nilfs_super_block *sbp)
799 {
800 	struct the_nilfs *nilfs = sb->s_fs_info;
801 
802 	nilfs->ns_mount_opt =
803 		NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
804 }
805 
806 static int nilfs_setup_super(struct super_block *sb, int is_mount)
807 {
808 	struct the_nilfs *nilfs = sb->s_fs_info;
809 	struct nilfs_super_block **sbp;
810 	int max_mnt_count;
811 	int mnt_count;
812 
813 	/* nilfs->ns_sem must be locked by the caller. */
814 	sbp = nilfs_prepare_super(sb, 0);
815 	if (!sbp)
816 		return -EIO;
817 
818 	if (!is_mount)
819 		goto skip_mount_setup;
820 
821 	max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
822 	mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
823 
824 	if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
825 		nilfs_warn(sb, "mounting fs with errors");
826 #if 0
827 	} else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
828 		nilfs_warn(sb, "maximal mount count reached");
829 #endif
830 	}
831 	if (!max_mnt_count)
832 		sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
833 
834 	sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
835 	sbp[0]->s_mtime = cpu_to_le64(ktime_get_real_seconds());
836 
837 skip_mount_setup:
838 	sbp[0]->s_state =
839 		cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
840 	/* synchronize sbp[1] with sbp[0] */
841 	if (sbp[1])
842 		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
843 	return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
844 }
845 
846 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
847 						 u64 pos, int blocksize,
848 						 struct buffer_head **pbh)
849 {
850 	unsigned long long sb_index = pos;
851 	unsigned long offset;
852 
853 	offset = do_div(sb_index, blocksize);
854 	*pbh = sb_bread(sb, sb_index);
855 	if (!*pbh)
856 		return NULL;
857 	return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
858 }
859 
860 int nilfs_store_magic_and_option(struct super_block *sb,
861 				 struct nilfs_super_block *sbp,
862 				 char *data)
863 {
864 	struct the_nilfs *nilfs = sb->s_fs_info;
865 
866 	sb->s_magic = le16_to_cpu(sbp->s_magic);
867 
868 	/* FS independent flags */
869 #ifdef NILFS_ATIME_DISABLE
870 	sb->s_flags |= SB_NOATIME;
871 #endif
872 
873 	nilfs_set_default_options(sb, sbp);
874 
875 	nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
876 	nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
877 	nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
878 	nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
879 
880 	return !parse_options(data, sb, 0) ? -EINVAL : 0;
881 }
882 
883 int nilfs_check_feature_compatibility(struct super_block *sb,
884 				      struct nilfs_super_block *sbp)
885 {
886 	__u64 features;
887 
888 	features = le64_to_cpu(sbp->s_feature_incompat) &
889 		~NILFS_FEATURE_INCOMPAT_SUPP;
890 	if (features) {
891 		nilfs_err(sb,
892 			  "couldn't mount because of unsupported optional features (%llx)",
893 			  (unsigned long long)features);
894 		return -EINVAL;
895 	}
896 	features = le64_to_cpu(sbp->s_feature_compat_ro) &
897 		~NILFS_FEATURE_COMPAT_RO_SUPP;
898 	if (!sb_rdonly(sb) && features) {
899 		nilfs_err(sb,
900 			  "couldn't mount RDWR because of unsupported optional features (%llx)",
901 			  (unsigned long long)features);
902 		return -EINVAL;
903 	}
904 	return 0;
905 }
906 
907 static int nilfs_get_root_dentry(struct super_block *sb,
908 				 struct nilfs_root *root,
909 				 struct dentry **root_dentry)
910 {
911 	struct inode *inode;
912 	struct dentry *dentry;
913 	int ret = 0;
914 
915 	inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
916 	if (IS_ERR(inode)) {
917 		ret = PTR_ERR(inode);
918 		nilfs_err(sb, "error %d getting root inode", ret);
919 		goto out;
920 	}
921 	if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
922 		iput(inode);
923 		nilfs_err(sb, "corrupt root inode");
924 		ret = -EINVAL;
925 		goto out;
926 	}
927 
928 	if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
929 		dentry = d_find_alias(inode);
930 		if (!dentry) {
931 			dentry = d_make_root(inode);
932 			if (!dentry) {
933 				ret = -ENOMEM;
934 				goto failed_dentry;
935 			}
936 		} else {
937 			iput(inode);
938 		}
939 	} else {
940 		dentry = d_obtain_root(inode);
941 		if (IS_ERR(dentry)) {
942 			ret = PTR_ERR(dentry);
943 			goto failed_dentry;
944 		}
945 	}
946 	*root_dentry = dentry;
947  out:
948 	return ret;
949 
950  failed_dentry:
951 	nilfs_err(sb, "error %d getting root dentry", ret);
952 	goto out;
953 }
954 
955 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
956 				 struct dentry **root_dentry)
957 {
958 	struct the_nilfs *nilfs = s->s_fs_info;
959 	struct nilfs_root *root;
960 	int ret;
961 
962 	mutex_lock(&nilfs->ns_snapshot_mount_mutex);
963 
964 	down_read(&nilfs->ns_segctor_sem);
965 	ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
966 	up_read(&nilfs->ns_segctor_sem);
967 	if (ret < 0) {
968 		ret = (ret == -ENOENT) ? -EINVAL : ret;
969 		goto out;
970 	} else if (!ret) {
971 		nilfs_err(s,
972 			  "The specified checkpoint is not a snapshot (checkpoint number=%llu)",
973 			  (unsigned long long)cno);
974 		ret = -EINVAL;
975 		goto out;
976 	}
977 
978 	ret = nilfs_attach_checkpoint(s, cno, false, &root);
979 	if (ret) {
980 		nilfs_err(s,
981 			  "error %d while loading snapshot (checkpoint number=%llu)",
982 			  ret, (unsigned long long)cno);
983 		goto out;
984 	}
985 	ret = nilfs_get_root_dentry(s, root, root_dentry);
986 	nilfs_put_root(root);
987  out:
988 	mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
989 	return ret;
990 }
991 
992 /**
993  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
994  * @root_dentry: root dentry of the tree to be shrunk
995  *
996  * This function returns true if the tree was in-use.
997  */
998 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
999 {
1000 	shrink_dcache_parent(root_dentry);
1001 	return d_count(root_dentry) > 1;
1002 }
1003 
1004 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1005 {
1006 	struct the_nilfs *nilfs = sb->s_fs_info;
1007 	struct nilfs_root *root;
1008 	struct inode *inode;
1009 	struct dentry *dentry;
1010 	int ret;
1011 
1012 	if (cno > nilfs->ns_cno)
1013 		return false;
1014 
1015 	if (cno >= nilfs_last_cno(nilfs))
1016 		return true;	/* protect recent checkpoints */
1017 
1018 	ret = false;
1019 	root = nilfs_lookup_root(nilfs, cno);
1020 	if (root) {
1021 		inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1022 		if (inode) {
1023 			dentry = d_find_alias(inode);
1024 			if (dentry) {
1025 				ret = nilfs_tree_is_busy(dentry);
1026 				dput(dentry);
1027 			}
1028 			iput(inode);
1029 		}
1030 		nilfs_put_root(root);
1031 	}
1032 	return ret;
1033 }
1034 
1035 /**
1036  * nilfs_fill_super() - initialize a super block instance
1037  * @sb: super_block
1038  * @data: mount options
1039  * @silent: silent mode flag
1040  *
1041  * This function is called exclusively by nilfs->ns_mount_mutex.
1042  * So, the recovery process is protected from other simultaneous mounts.
1043  */
1044 static int
1045 nilfs_fill_super(struct super_block *sb, void *data, int silent)
1046 {
1047 	struct the_nilfs *nilfs;
1048 	struct nilfs_root *fsroot;
1049 	__u64 cno;
1050 	int err;
1051 
1052 	nilfs = alloc_nilfs(sb);
1053 	if (!nilfs)
1054 		return -ENOMEM;
1055 
1056 	sb->s_fs_info = nilfs;
1057 
1058 	err = init_nilfs(nilfs, sb, (char *)data);
1059 	if (err)
1060 		goto failed_nilfs;
1061 
1062 	sb->s_op = &nilfs_sops;
1063 	sb->s_export_op = &nilfs_export_ops;
1064 	sb->s_root = NULL;
1065 	sb->s_time_gran = 1;
1066 	sb->s_max_links = NILFS_LINK_MAX;
1067 
1068 	sb->s_bdi = bdi_get(sb->s_bdev->bd_disk->bdi);
1069 
1070 	err = load_nilfs(nilfs, sb);
1071 	if (err)
1072 		goto failed_nilfs;
1073 
1074 	cno = nilfs_last_cno(nilfs);
1075 	err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1076 	if (err) {
1077 		nilfs_err(sb,
1078 			  "error %d while loading last checkpoint (checkpoint number=%llu)",
1079 			  err, (unsigned long long)cno);
1080 		goto failed_unload;
1081 	}
1082 
1083 	if (!sb_rdonly(sb)) {
1084 		err = nilfs_attach_log_writer(sb, fsroot);
1085 		if (err)
1086 			goto failed_checkpoint;
1087 	}
1088 
1089 	err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1090 	if (err)
1091 		goto failed_segctor;
1092 
1093 	nilfs_put_root(fsroot);
1094 
1095 	if (!sb_rdonly(sb)) {
1096 		down_write(&nilfs->ns_sem);
1097 		nilfs_setup_super(sb, true);
1098 		up_write(&nilfs->ns_sem);
1099 	}
1100 
1101 	return 0;
1102 
1103  failed_segctor:
1104 	nilfs_detach_log_writer(sb);
1105 
1106  failed_checkpoint:
1107 	nilfs_put_root(fsroot);
1108 
1109  failed_unload:
1110 	nilfs_sysfs_delete_device_group(nilfs);
1111 	iput(nilfs->ns_sufile);
1112 	iput(nilfs->ns_cpfile);
1113 	iput(nilfs->ns_dat);
1114 
1115  failed_nilfs:
1116 	destroy_nilfs(nilfs);
1117 	return err;
1118 }
1119 
1120 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1121 {
1122 	struct the_nilfs *nilfs = sb->s_fs_info;
1123 	unsigned long old_sb_flags;
1124 	unsigned long old_mount_opt;
1125 	int err;
1126 
1127 	sync_filesystem(sb);
1128 	old_sb_flags = sb->s_flags;
1129 	old_mount_opt = nilfs->ns_mount_opt;
1130 
1131 	if (!parse_options(data, sb, 1)) {
1132 		err = -EINVAL;
1133 		goto restore_opts;
1134 	}
1135 	sb->s_flags = (sb->s_flags & ~SB_POSIXACL);
1136 
1137 	err = -EINVAL;
1138 
1139 	if (!nilfs_valid_fs(nilfs)) {
1140 		nilfs_warn(sb,
1141 			   "couldn't remount because the filesystem is in an incomplete recovery state");
1142 		goto restore_opts;
1143 	}
1144 
1145 	if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
1146 		goto out;
1147 	if (*flags & SB_RDONLY) {
1148 		sb->s_flags |= SB_RDONLY;
1149 
1150 		/*
1151 		 * Remounting a valid RW partition RDONLY, so set
1152 		 * the RDONLY flag and then mark the partition as valid again.
1153 		 */
1154 		down_write(&nilfs->ns_sem);
1155 		nilfs_cleanup_super(sb);
1156 		up_write(&nilfs->ns_sem);
1157 	} else {
1158 		__u64 features;
1159 		struct nilfs_root *root;
1160 
1161 		/*
1162 		 * Mounting a RDONLY partition read-write, so reread and
1163 		 * store the current valid flag.  (It may have been changed
1164 		 * by fsck since we originally mounted the partition.)
1165 		 */
1166 		down_read(&nilfs->ns_sem);
1167 		features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1168 			~NILFS_FEATURE_COMPAT_RO_SUPP;
1169 		up_read(&nilfs->ns_sem);
1170 		if (features) {
1171 			nilfs_warn(sb,
1172 				   "couldn't remount RDWR because of unsupported optional features (%llx)",
1173 				   (unsigned long long)features);
1174 			err = -EROFS;
1175 			goto restore_opts;
1176 		}
1177 
1178 		sb->s_flags &= ~SB_RDONLY;
1179 
1180 		root = NILFS_I(d_inode(sb->s_root))->i_root;
1181 		err = nilfs_attach_log_writer(sb, root);
1182 		if (err)
1183 			goto restore_opts;
1184 
1185 		down_write(&nilfs->ns_sem);
1186 		nilfs_setup_super(sb, true);
1187 		up_write(&nilfs->ns_sem);
1188 	}
1189  out:
1190 	return 0;
1191 
1192  restore_opts:
1193 	sb->s_flags = old_sb_flags;
1194 	nilfs->ns_mount_opt = old_mount_opt;
1195 	return err;
1196 }
1197 
1198 struct nilfs_super_data {
1199 	__u64 cno;
1200 	int flags;
1201 };
1202 
1203 static int nilfs_parse_snapshot_option(const char *option,
1204 				       const substring_t *arg,
1205 				       struct nilfs_super_data *sd)
1206 {
1207 	unsigned long long val;
1208 	const char *msg = NULL;
1209 	int err;
1210 
1211 	if (!(sd->flags & SB_RDONLY)) {
1212 		msg = "read-only option is not specified";
1213 		goto parse_error;
1214 	}
1215 
1216 	err = kstrtoull(arg->from, 0, &val);
1217 	if (err) {
1218 		if (err == -ERANGE)
1219 			msg = "too large checkpoint number";
1220 		else
1221 			msg = "malformed argument";
1222 		goto parse_error;
1223 	} else if (val == 0) {
1224 		msg = "invalid checkpoint number 0";
1225 		goto parse_error;
1226 	}
1227 	sd->cno = val;
1228 	return 0;
1229 
1230 parse_error:
1231 	nilfs_err(NULL, "invalid option \"%s\": %s", option, msg);
1232 	return 1;
1233 }
1234 
1235 /**
1236  * nilfs_identify - pre-read mount options needed to identify mount instance
1237  * @data: mount options
1238  * @sd: nilfs_super_data
1239  */
1240 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1241 {
1242 	char *p, *options = data;
1243 	substring_t args[MAX_OPT_ARGS];
1244 	int token;
1245 	int ret = 0;
1246 
1247 	do {
1248 		p = strsep(&options, ",");
1249 		if (p != NULL && *p) {
1250 			token = match_token(p, tokens, args);
1251 			if (token == Opt_snapshot)
1252 				ret = nilfs_parse_snapshot_option(p, &args[0],
1253 								  sd);
1254 		}
1255 		if (!options)
1256 			break;
1257 		BUG_ON(options == data);
1258 		*(options - 1) = ',';
1259 	} while (!ret);
1260 	return ret;
1261 }
1262 
1263 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1264 {
1265 	s->s_dev = *(dev_t *)data;
1266 	return 0;
1267 }
1268 
1269 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1270 {
1271 	return !(s->s_iflags & SB_I_RETIRED) && s->s_dev == *(dev_t *)data;
1272 }
1273 
1274 static struct dentry *
1275 nilfs_mount(struct file_system_type *fs_type, int flags,
1276 	     const char *dev_name, void *data)
1277 {
1278 	struct nilfs_super_data sd = { .flags = flags };
1279 	struct super_block *s;
1280 	dev_t dev;
1281 	int err;
1282 
1283 	if (nilfs_identify(data, &sd))
1284 		return ERR_PTR(-EINVAL);
1285 
1286 	err = lookup_bdev(dev_name, &dev);
1287 	if (err)
1288 		return ERR_PTR(err);
1289 
1290 	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
1291 		 &dev);
1292 	if (IS_ERR(s))
1293 		return ERR_CAST(s);
1294 
1295 	if (!s->s_root) {
1296 		err = setup_bdev_super(s, flags, NULL);
1297 		if (!err)
1298 			err = nilfs_fill_super(s, data,
1299 					       flags & SB_SILENT ? 1 : 0);
1300 		if (err)
1301 			goto failed_super;
1302 
1303 		s->s_flags |= SB_ACTIVE;
1304 	} else if (!sd.cno) {
1305 		if (nilfs_tree_is_busy(s->s_root)) {
1306 			if ((flags ^ s->s_flags) & SB_RDONLY) {
1307 				nilfs_err(s,
1308 					  "the device already has a %s mount.",
1309 					  sb_rdonly(s) ? "read-only" : "read/write");
1310 				err = -EBUSY;
1311 				goto failed_super;
1312 			}
1313 		} else {
1314 			/*
1315 			 * Try remount to setup mount states if the current
1316 			 * tree is not mounted and only snapshots use this sb.
1317 			 */
1318 			err = nilfs_remount(s, &flags, data);
1319 			if (err)
1320 				goto failed_super;
1321 		}
1322 	}
1323 
1324 	if (sd.cno) {
1325 		struct dentry *root_dentry;
1326 
1327 		err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1328 		if (err)
1329 			goto failed_super;
1330 		return root_dentry;
1331 	}
1332 
1333 	return dget(s->s_root);
1334 
1335  failed_super:
1336 	deactivate_locked_super(s);
1337 	return ERR_PTR(err);
1338 }
1339 
1340 struct file_system_type nilfs_fs_type = {
1341 	.owner    = THIS_MODULE,
1342 	.name     = "nilfs2",
1343 	.mount    = nilfs_mount,
1344 	.kill_sb  = kill_block_super,
1345 	.fs_flags = FS_REQUIRES_DEV,
1346 };
1347 MODULE_ALIAS_FS("nilfs2");
1348 
1349 static void nilfs_inode_init_once(void *obj)
1350 {
1351 	struct nilfs_inode_info *ii = obj;
1352 
1353 	INIT_LIST_HEAD(&ii->i_dirty);
1354 #ifdef CONFIG_NILFS_XATTR
1355 	init_rwsem(&ii->xattr_sem);
1356 #endif
1357 	inode_init_once(&ii->vfs_inode);
1358 }
1359 
1360 static void nilfs_segbuf_init_once(void *obj)
1361 {
1362 	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1363 }
1364 
1365 static void nilfs_destroy_cachep(void)
1366 {
1367 	/*
1368 	 * Make sure all delayed rcu free inodes are flushed before we
1369 	 * destroy cache.
1370 	 */
1371 	rcu_barrier();
1372 
1373 	kmem_cache_destroy(nilfs_inode_cachep);
1374 	kmem_cache_destroy(nilfs_transaction_cachep);
1375 	kmem_cache_destroy(nilfs_segbuf_cachep);
1376 	kmem_cache_destroy(nilfs_btree_path_cache);
1377 }
1378 
1379 static int __init nilfs_init_cachep(void)
1380 {
1381 	nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1382 			sizeof(struct nilfs_inode_info), 0,
1383 			SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
1384 			nilfs_inode_init_once);
1385 	if (!nilfs_inode_cachep)
1386 		goto fail;
1387 
1388 	nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1389 			sizeof(struct nilfs_transaction_info), 0,
1390 			SLAB_RECLAIM_ACCOUNT, NULL);
1391 	if (!nilfs_transaction_cachep)
1392 		goto fail;
1393 
1394 	nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1395 			sizeof(struct nilfs_segment_buffer), 0,
1396 			SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1397 	if (!nilfs_segbuf_cachep)
1398 		goto fail;
1399 
1400 	nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1401 			sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1402 			0, 0, NULL);
1403 	if (!nilfs_btree_path_cache)
1404 		goto fail;
1405 
1406 	return 0;
1407 
1408 fail:
1409 	nilfs_destroy_cachep();
1410 	return -ENOMEM;
1411 }
1412 
1413 static int __init init_nilfs_fs(void)
1414 {
1415 	int err;
1416 
1417 	err = nilfs_init_cachep();
1418 	if (err)
1419 		goto fail;
1420 
1421 	err = nilfs_sysfs_init();
1422 	if (err)
1423 		goto free_cachep;
1424 
1425 	err = register_filesystem(&nilfs_fs_type);
1426 	if (err)
1427 		goto deinit_sysfs_entry;
1428 
1429 	printk(KERN_INFO "NILFS version 2 loaded\n");
1430 	return 0;
1431 
1432 deinit_sysfs_entry:
1433 	nilfs_sysfs_exit();
1434 free_cachep:
1435 	nilfs_destroy_cachep();
1436 fail:
1437 	return err;
1438 }
1439 
1440 static void __exit exit_nilfs_fs(void)
1441 {
1442 	nilfs_destroy_cachep();
1443 	nilfs_sysfs_exit();
1444 	unregister_filesystem(&nilfs_fs_type);
1445 }
1446 
1447 module_init(init_nilfs_fs)
1448 module_exit(exit_nilfs_fs)
1449