xref: /linux/fs/nilfs2/super.c (revision cf21f328fcafacf4f96e7a30ef9dceede1076378)
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 "nilfs.h"
39 #include "export.h"
40 #include "mdt.h"
41 #include "alloc.h"
42 #include "btree.h"
43 #include "btnode.h"
44 #include "page.h"
45 #include "cpfile.h"
46 #include "sufile.h" /* nilfs_sufile_resize(), nilfs_sufile_set_alloc_range() */
47 #include "ifile.h"
48 #include "dat.h"
49 #include "segment.h"
50 #include "segbuf.h"
51 
52 MODULE_AUTHOR("NTT Corp.");
53 MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
54 		   "(NILFS)");
55 MODULE_LICENSE("GPL");
56 
57 static struct kmem_cache *nilfs_inode_cachep;
58 struct kmem_cache *nilfs_transaction_cachep;
59 struct kmem_cache *nilfs_segbuf_cachep;
60 struct kmem_cache *nilfs_btree_path_cache;
61 
62 static int nilfs_setup_super(struct super_block *sb, int is_mount);
63 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
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  *
109  * __nilfs_error() sets an ERROR_FS flag on the superblock as well as
110  * reporting an error message.  This function should be called when
111  * NILFS detects incoherences or defects of meta data on disk.
112  *
113  * This implements the body of nilfs_error() macro.  Normally,
114  * nilfs_error() should be used.  As for sustainable errors such as a
115  * single-shot I/O error, nilfs_err() should be used instead.
116  *
117  * Callers should not add a trailing newline since this will do it.
118  */
119 void __nilfs_error(struct super_block *sb, const char *function,
120 		   const char *fmt, ...)
121 {
122 	struct the_nilfs *nilfs = sb->s_fs_info;
123 	struct va_format vaf;
124 	va_list args;
125 
126 	va_start(args, fmt);
127 
128 	vaf.fmt = fmt;
129 	vaf.va = &args;
130 
131 	printk(KERN_CRIT "NILFS error (device %s): %s: %pV\n",
132 	       sb->s_id, function, &vaf);
133 
134 	va_end(args);
135 
136 	if (!sb_rdonly(sb)) {
137 		nilfs_set_error(sb);
138 
139 		if (nilfs_test_opt(nilfs, ERRORS_RO)) {
140 			printk(KERN_CRIT "Remounting filesystem read-only\n");
141 			sb->s_flags |= SB_RDONLY;
142 		}
143 	}
144 
145 	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
146 		panic("NILFS (device %s): panic forced after error\n",
147 		      sb->s_id);
148 }
149 
150 struct inode *nilfs_alloc_inode(struct super_block *sb)
151 {
152 	struct nilfs_inode_info *ii;
153 
154 	ii = alloc_inode_sb(sb, nilfs_inode_cachep, GFP_NOFS);
155 	if (!ii)
156 		return NULL;
157 	ii->i_bh = NULL;
158 	ii->i_state = 0;
159 	ii->i_cno = 0;
160 	ii->i_assoc_inode = NULL;
161 	ii->i_bmap = &ii->i_bmap_data;
162 	return &ii->vfs_inode;
163 }
164 
165 static void nilfs_free_inode(struct inode *inode)
166 {
167 	if (nilfs_is_metadata_file_inode(inode))
168 		nilfs_mdt_destroy(inode);
169 
170 	kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
171 }
172 
173 static int nilfs_sync_super(struct super_block *sb, int flag)
174 {
175 	struct the_nilfs *nilfs = sb->s_fs_info;
176 	int err;
177 
178  retry:
179 	set_buffer_dirty(nilfs->ns_sbh[0]);
180 	if (nilfs_test_opt(nilfs, BARRIER)) {
181 		err = __sync_dirty_buffer(nilfs->ns_sbh[0],
182 					  REQ_SYNC | REQ_PREFLUSH | REQ_FUA);
183 	} else {
184 		err = sync_dirty_buffer(nilfs->ns_sbh[0]);
185 	}
186 
187 	if (unlikely(err)) {
188 		nilfs_err(sb, "unable to write superblock: err=%d", err);
189 		if (err == -EIO && nilfs->ns_sbh[1]) {
190 			/*
191 			 * sbp[0] points to newer log than sbp[1],
192 			 * so copy sbp[0] to sbp[1] to take over sbp[0].
193 			 */
194 			memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
195 			       nilfs->ns_sbsize);
196 			nilfs_fall_back_super_block(nilfs);
197 			goto retry;
198 		}
199 	} else {
200 		struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
201 
202 		nilfs->ns_sbwcount++;
203 
204 		/*
205 		 * The latest segment becomes trailable from the position
206 		 * written in superblock.
207 		 */
208 		clear_nilfs_discontinued(nilfs);
209 
210 		/* update GC protection for recent segments */
211 		if (nilfs->ns_sbh[1]) {
212 			if (flag == NILFS_SB_COMMIT_ALL) {
213 				set_buffer_dirty(nilfs->ns_sbh[1]);
214 				if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
215 					goto out;
216 			}
217 			if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
218 			    le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
219 				sbp = nilfs->ns_sbp[1];
220 		}
221 
222 		spin_lock(&nilfs->ns_last_segment_lock);
223 		nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
224 		spin_unlock(&nilfs->ns_last_segment_lock);
225 	}
226  out:
227 	return err;
228 }
229 
230 void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
231 			  struct the_nilfs *nilfs)
232 {
233 	sector_t nfreeblocks;
234 
235 	/* nilfs->ns_sem must be locked by the caller. */
236 	nilfs_count_free_blocks(nilfs, &nfreeblocks);
237 	sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
238 
239 	spin_lock(&nilfs->ns_last_segment_lock);
240 	sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
241 	sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
242 	sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
243 	spin_unlock(&nilfs->ns_last_segment_lock);
244 }
245 
246 struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
247 					       int flip)
248 {
249 	struct the_nilfs *nilfs = sb->s_fs_info;
250 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
251 
252 	/* nilfs->ns_sem must be locked by the caller. */
253 	if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
254 		if (sbp[1] &&
255 		    sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
256 			memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
257 		} else {
258 			nilfs_crit(sb, "superblock broke");
259 			return NULL;
260 		}
261 	} else if (sbp[1] &&
262 		   sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
263 		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
264 	}
265 
266 	if (flip && sbp[1])
267 		nilfs_swap_super_block(nilfs);
268 
269 	return sbp;
270 }
271 
272 int nilfs_commit_super(struct super_block *sb, int flag)
273 {
274 	struct the_nilfs *nilfs = sb->s_fs_info;
275 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
276 	time64_t t;
277 
278 	/* nilfs->ns_sem must be locked by the caller. */
279 	t = ktime_get_real_seconds();
280 	nilfs->ns_sbwtime = t;
281 	sbp[0]->s_wtime = cpu_to_le64(t);
282 	sbp[0]->s_sum = 0;
283 	sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
284 					     (unsigned char *)sbp[0],
285 					     nilfs->ns_sbsize));
286 	if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
287 		sbp[1]->s_wtime = sbp[0]->s_wtime;
288 		sbp[1]->s_sum = 0;
289 		sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
290 					    (unsigned char *)sbp[1],
291 					    nilfs->ns_sbsize));
292 	}
293 	clear_nilfs_sb_dirty(nilfs);
294 	nilfs->ns_flushed_device = 1;
295 	/* make sure store to ns_flushed_device cannot be reordered */
296 	smp_wmb();
297 	return nilfs_sync_super(sb, flag);
298 }
299 
300 /**
301  * nilfs_cleanup_super() - write filesystem state for cleanup
302  * @sb: super block instance to be unmounted or degraded to read-only
303  *
304  * This function restores state flags in the on-disk super block.
305  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
306  * filesystem was not clean previously.
307  */
308 int nilfs_cleanup_super(struct super_block *sb)
309 {
310 	struct the_nilfs *nilfs = sb->s_fs_info;
311 	struct nilfs_super_block **sbp;
312 	int flag = NILFS_SB_COMMIT;
313 	int ret = -EIO;
314 
315 	sbp = nilfs_prepare_super(sb, 0);
316 	if (sbp) {
317 		sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
318 		nilfs_set_log_cursor(sbp[0], nilfs);
319 		if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
320 			/*
321 			 * make the "clean" flag also to the opposite
322 			 * super block if both super blocks point to
323 			 * the same checkpoint.
324 			 */
325 			sbp[1]->s_state = sbp[0]->s_state;
326 			flag = NILFS_SB_COMMIT_ALL;
327 		}
328 		ret = nilfs_commit_super(sb, flag);
329 	}
330 	return ret;
331 }
332 
333 /**
334  * nilfs_move_2nd_super - relocate secondary super block
335  * @sb: super block instance
336  * @sb2off: new offset of the secondary super block (in bytes)
337  */
338 static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
339 {
340 	struct the_nilfs *nilfs = sb->s_fs_info;
341 	struct buffer_head *nsbh;
342 	struct nilfs_super_block *nsbp;
343 	sector_t blocknr, newblocknr;
344 	unsigned long offset;
345 	int sb2i;  /* array index of the secondary superblock */
346 	int ret = 0;
347 
348 	/* nilfs->ns_sem must be locked by the caller. */
349 	if (nilfs->ns_sbh[1] &&
350 	    nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
351 		sb2i = 1;
352 		blocknr = nilfs->ns_sbh[1]->b_blocknr;
353 	} else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
354 		sb2i = 0;
355 		blocknr = nilfs->ns_sbh[0]->b_blocknr;
356 	} else {
357 		sb2i = -1;
358 		blocknr = 0;
359 	}
360 	if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
361 		goto out;  /* super block location is unchanged */
362 
363 	/* Get new super block buffer */
364 	newblocknr = sb2off >> nilfs->ns_blocksize_bits;
365 	offset = sb2off & (nilfs->ns_blocksize - 1);
366 	nsbh = sb_getblk(sb, newblocknr);
367 	if (!nsbh) {
368 		nilfs_warn(sb,
369 			   "unable to move secondary superblock to block %llu",
370 			   (unsigned long long)newblocknr);
371 		ret = -EIO;
372 		goto out;
373 	}
374 	nsbp = (void *)nsbh->b_data + offset;
375 	memset(nsbp, 0, nilfs->ns_blocksize);
376 
377 	if (sb2i >= 0) {
378 		memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
379 		brelse(nilfs->ns_sbh[sb2i]);
380 		nilfs->ns_sbh[sb2i] = nsbh;
381 		nilfs->ns_sbp[sb2i] = nsbp;
382 	} else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
383 		/* secondary super block will be restored to index 1 */
384 		nilfs->ns_sbh[1] = nsbh;
385 		nilfs->ns_sbp[1] = nsbp;
386 	} else {
387 		brelse(nsbh);
388 	}
389 out:
390 	return ret;
391 }
392 
393 /**
394  * nilfs_resize_fs - resize the filesystem
395  * @sb: super block instance
396  * @newsize: new size of the filesystem (in bytes)
397  */
398 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
399 {
400 	struct the_nilfs *nilfs = sb->s_fs_info;
401 	struct nilfs_super_block **sbp;
402 	__u64 devsize, newnsegs;
403 	loff_t sb2off;
404 	int ret;
405 
406 	ret = -ERANGE;
407 	devsize = bdev_nr_bytes(sb->s_bdev);
408 	if (newsize > devsize)
409 		goto out;
410 
411 	/*
412 	 * Prevent underflow in second superblock position calculation.
413 	 * The exact minimum size check is done in nilfs_sufile_resize().
414 	 */
415 	if (newsize < 4096) {
416 		ret = -ENOSPC;
417 		goto out;
418 	}
419 
420 	/*
421 	 * Write lock is required to protect some functions depending
422 	 * on the number of segments, the number of reserved segments,
423 	 * and so forth.
424 	 */
425 	down_write(&nilfs->ns_segctor_sem);
426 
427 	sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
428 	newnsegs = sb2off >> nilfs->ns_blocksize_bits;
429 	do_div(newnsegs, nilfs->ns_blocks_per_segment);
430 
431 	ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
432 	up_write(&nilfs->ns_segctor_sem);
433 	if (ret < 0)
434 		goto out;
435 
436 	ret = nilfs_construct_segment(sb);
437 	if (ret < 0)
438 		goto out;
439 
440 	down_write(&nilfs->ns_sem);
441 	nilfs_move_2nd_super(sb, sb2off);
442 	ret = -EIO;
443 	sbp = nilfs_prepare_super(sb, 0);
444 	if (likely(sbp)) {
445 		nilfs_set_log_cursor(sbp[0], nilfs);
446 		/*
447 		 * Drop NILFS_RESIZE_FS flag for compatibility with
448 		 * mount-time resize which may be implemented in a
449 		 * future release.
450 		 */
451 		sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
452 					      ~NILFS_RESIZE_FS);
453 		sbp[0]->s_dev_size = cpu_to_le64(newsize);
454 		sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
455 		if (sbp[1])
456 			memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
457 		ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
458 	}
459 	up_write(&nilfs->ns_sem);
460 
461 	/*
462 	 * Reset the range of allocatable segments last.  This order
463 	 * is important in the case of expansion because the secondary
464 	 * superblock must be protected from log write until migration
465 	 * completes.
466 	 */
467 	if (!ret)
468 		nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
469 out:
470 	return ret;
471 }
472 
473 static void nilfs_put_super(struct super_block *sb)
474 {
475 	struct the_nilfs *nilfs = sb->s_fs_info;
476 
477 	nilfs_detach_log_writer(sb);
478 
479 	if (!sb_rdonly(sb)) {
480 		down_write(&nilfs->ns_sem);
481 		nilfs_cleanup_super(sb);
482 		up_write(&nilfs->ns_sem);
483 	}
484 
485 	iput(nilfs->ns_sufile);
486 	iput(nilfs->ns_cpfile);
487 	iput(nilfs->ns_dat);
488 
489 	destroy_nilfs(nilfs);
490 	sb->s_fs_info = NULL;
491 }
492 
493 static int nilfs_sync_fs(struct super_block *sb, int wait)
494 {
495 	struct the_nilfs *nilfs = sb->s_fs_info;
496 	struct nilfs_super_block **sbp;
497 	int err = 0;
498 
499 	/* This function is called when super block should be written back */
500 	if (wait)
501 		err = nilfs_construct_segment(sb);
502 
503 	down_write(&nilfs->ns_sem);
504 	if (nilfs_sb_dirty(nilfs)) {
505 		sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
506 		if (likely(sbp)) {
507 			nilfs_set_log_cursor(sbp[0], nilfs);
508 			nilfs_commit_super(sb, NILFS_SB_COMMIT);
509 		}
510 	}
511 	up_write(&nilfs->ns_sem);
512 
513 	if (!err)
514 		err = nilfs_flush_device(nilfs);
515 
516 	return err;
517 }
518 
519 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
520 			    struct nilfs_root **rootp)
521 {
522 	struct the_nilfs *nilfs = sb->s_fs_info;
523 	struct nilfs_root *root;
524 	struct nilfs_checkpoint *raw_cp;
525 	struct buffer_head *bh_cp;
526 	int err = -ENOMEM;
527 
528 	root = nilfs_find_or_create_root(
529 		nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
530 	if (!root)
531 		return err;
532 
533 	if (root->ifile)
534 		goto reuse; /* already attached checkpoint */
535 
536 	down_read(&nilfs->ns_segctor_sem);
537 	err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
538 					  &bh_cp);
539 	up_read(&nilfs->ns_segctor_sem);
540 	if (unlikely(err)) {
541 		if (err == -ENOENT || err == -EINVAL) {
542 			nilfs_err(sb,
543 				  "Invalid checkpoint (checkpoint number=%llu)",
544 				  (unsigned long long)cno);
545 			err = -EINVAL;
546 		}
547 		goto failed;
548 	}
549 
550 	err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
551 			       &raw_cp->cp_ifile_inode, &root->ifile);
552 	if (err)
553 		goto failed_bh;
554 
555 	atomic64_set(&root->inodes_count,
556 			le64_to_cpu(raw_cp->cp_inodes_count));
557 	atomic64_set(&root->blocks_count,
558 			le64_to_cpu(raw_cp->cp_blocks_count));
559 
560 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
561 
562  reuse:
563 	*rootp = root;
564 	return 0;
565 
566  failed_bh:
567 	nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
568  failed:
569 	nilfs_put_root(root);
570 
571 	return err;
572 }
573 
574 static int nilfs_freeze(struct super_block *sb)
575 {
576 	struct the_nilfs *nilfs = sb->s_fs_info;
577 	int err;
578 
579 	if (sb_rdonly(sb))
580 		return 0;
581 
582 	/* Mark super block clean */
583 	down_write(&nilfs->ns_sem);
584 	err = nilfs_cleanup_super(sb);
585 	up_write(&nilfs->ns_sem);
586 	return err;
587 }
588 
589 static int nilfs_unfreeze(struct super_block *sb)
590 {
591 	struct the_nilfs *nilfs = sb->s_fs_info;
592 
593 	if (sb_rdonly(sb))
594 		return 0;
595 
596 	down_write(&nilfs->ns_sem);
597 	nilfs_setup_super(sb, false);
598 	up_write(&nilfs->ns_sem);
599 	return 0;
600 }
601 
602 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
603 {
604 	struct super_block *sb = dentry->d_sb;
605 	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
606 	struct the_nilfs *nilfs = root->nilfs;
607 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
608 	unsigned long long blocks;
609 	unsigned long overhead;
610 	unsigned long nrsvblocks;
611 	sector_t nfreeblocks;
612 	u64 nmaxinodes, nfreeinodes;
613 	int err;
614 
615 	/*
616 	 * Compute all of the segment blocks
617 	 *
618 	 * The blocks before first segment and after last segment
619 	 * are excluded.
620 	 */
621 	blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
622 		- nilfs->ns_first_data_block;
623 	nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
624 
625 	/*
626 	 * Compute the overhead
627 	 *
628 	 * When distributing meta data blocks outside segment structure,
629 	 * We must count them as the overhead.
630 	 */
631 	overhead = 0;
632 
633 	err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
634 	if (unlikely(err))
635 		return err;
636 
637 	err = nilfs_ifile_count_free_inodes(root->ifile,
638 					    &nmaxinodes, &nfreeinodes);
639 	if (unlikely(err)) {
640 		nilfs_warn(sb, "failed to count free inodes: err=%d", err);
641 		if (err == -ERANGE) {
642 			/*
643 			 * If nilfs_palloc_count_max_entries() returns
644 			 * -ERANGE error code then we simply treat
645 			 * curent inodes count as maximum possible and
646 			 * zero as free inodes value.
647 			 */
648 			nmaxinodes = atomic64_read(&root->inodes_count);
649 			nfreeinodes = 0;
650 			err = 0;
651 		} else
652 			return err;
653 	}
654 
655 	buf->f_type = NILFS_SUPER_MAGIC;
656 	buf->f_bsize = sb->s_blocksize;
657 	buf->f_blocks = blocks - overhead;
658 	buf->f_bfree = nfreeblocks;
659 	buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
660 		(buf->f_bfree - nrsvblocks) : 0;
661 	buf->f_files = nmaxinodes;
662 	buf->f_ffree = nfreeinodes;
663 	buf->f_namelen = NILFS_NAME_LEN;
664 	buf->f_fsid = u64_to_fsid(id);
665 
666 	return 0;
667 }
668 
669 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
670 {
671 	struct super_block *sb = dentry->d_sb;
672 	struct the_nilfs *nilfs = sb->s_fs_info;
673 	struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
674 
675 	if (!nilfs_test_opt(nilfs, BARRIER))
676 		seq_puts(seq, ",nobarrier");
677 	if (root->cno != NILFS_CPTREE_CURRENT_CNO)
678 		seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
679 	if (nilfs_test_opt(nilfs, ERRORS_PANIC))
680 		seq_puts(seq, ",errors=panic");
681 	if (nilfs_test_opt(nilfs, ERRORS_CONT))
682 		seq_puts(seq, ",errors=continue");
683 	if (nilfs_test_opt(nilfs, STRICT_ORDER))
684 		seq_puts(seq, ",order=strict");
685 	if (nilfs_test_opt(nilfs, NORECOVERY))
686 		seq_puts(seq, ",norecovery");
687 	if (nilfs_test_opt(nilfs, DISCARD))
688 		seq_puts(seq, ",discard");
689 
690 	return 0;
691 }
692 
693 static const struct super_operations nilfs_sops = {
694 	.alloc_inode    = nilfs_alloc_inode,
695 	.free_inode     = nilfs_free_inode,
696 	.dirty_inode    = nilfs_dirty_inode,
697 	.evict_inode    = nilfs_evict_inode,
698 	.put_super      = nilfs_put_super,
699 	.sync_fs        = nilfs_sync_fs,
700 	.freeze_fs	= nilfs_freeze,
701 	.unfreeze_fs	= nilfs_unfreeze,
702 	.statfs         = nilfs_statfs,
703 	.remount_fs     = nilfs_remount,
704 	.show_options = nilfs_show_options
705 };
706 
707 enum {
708 	Opt_err_cont, Opt_err_panic, Opt_err_ro,
709 	Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
710 	Opt_discard, Opt_nodiscard, Opt_err,
711 };
712 
713 static match_table_t tokens = {
714 	{Opt_err_cont, "errors=continue"},
715 	{Opt_err_panic, "errors=panic"},
716 	{Opt_err_ro, "errors=remount-ro"},
717 	{Opt_barrier, "barrier"},
718 	{Opt_nobarrier, "nobarrier"},
719 	{Opt_snapshot, "cp=%u"},
720 	{Opt_order, "order=%s"},
721 	{Opt_norecovery, "norecovery"},
722 	{Opt_discard, "discard"},
723 	{Opt_nodiscard, "nodiscard"},
724 	{Opt_err, NULL}
725 };
726 
727 static int parse_options(char *options, struct super_block *sb, int is_remount)
728 {
729 	struct the_nilfs *nilfs = sb->s_fs_info;
730 	char *p;
731 	substring_t args[MAX_OPT_ARGS];
732 
733 	if (!options)
734 		return 1;
735 
736 	while ((p = strsep(&options, ",")) != NULL) {
737 		int token;
738 
739 		if (!*p)
740 			continue;
741 
742 		token = match_token(p, tokens, args);
743 		switch (token) {
744 		case Opt_barrier:
745 			nilfs_set_opt(nilfs, BARRIER);
746 			break;
747 		case Opt_nobarrier:
748 			nilfs_clear_opt(nilfs, BARRIER);
749 			break;
750 		case Opt_order:
751 			if (strcmp(args[0].from, "relaxed") == 0)
752 				/* Ordered data semantics */
753 				nilfs_clear_opt(nilfs, STRICT_ORDER);
754 			else if (strcmp(args[0].from, "strict") == 0)
755 				/* Strict in-order semantics */
756 				nilfs_set_opt(nilfs, STRICT_ORDER);
757 			else
758 				return 0;
759 			break;
760 		case Opt_err_panic:
761 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
762 			break;
763 		case Opt_err_ro:
764 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
765 			break;
766 		case Opt_err_cont:
767 			nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
768 			break;
769 		case Opt_snapshot:
770 			if (is_remount) {
771 				nilfs_err(sb,
772 					  "\"%s\" option is invalid for remount",
773 					  p);
774 				return 0;
775 			}
776 			break;
777 		case Opt_norecovery:
778 			nilfs_set_opt(nilfs, NORECOVERY);
779 			break;
780 		case Opt_discard:
781 			nilfs_set_opt(nilfs, DISCARD);
782 			break;
783 		case Opt_nodiscard:
784 			nilfs_clear_opt(nilfs, DISCARD);
785 			break;
786 		default:
787 			nilfs_err(sb, "unrecognized mount option \"%s\"", p);
788 			return 0;
789 		}
790 	}
791 	return 1;
792 }
793 
794 static inline void
795 nilfs_set_default_options(struct super_block *sb,
796 			  struct nilfs_super_block *sbp)
797 {
798 	struct the_nilfs *nilfs = sb->s_fs_info;
799 
800 	nilfs->ns_mount_opt =
801 		NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
802 }
803 
804 static int nilfs_setup_super(struct super_block *sb, int is_mount)
805 {
806 	struct the_nilfs *nilfs = sb->s_fs_info;
807 	struct nilfs_super_block **sbp;
808 	int max_mnt_count;
809 	int mnt_count;
810 
811 	/* nilfs->ns_sem must be locked by the caller. */
812 	sbp = nilfs_prepare_super(sb, 0);
813 	if (!sbp)
814 		return -EIO;
815 
816 	if (!is_mount)
817 		goto skip_mount_setup;
818 
819 	max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
820 	mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
821 
822 	if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
823 		nilfs_warn(sb, "mounting fs with errors");
824 #if 0
825 	} else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
826 		nilfs_warn(sb, "maximal mount count reached");
827 #endif
828 	}
829 	if (!max_mnt_count)
830 		sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
831 
832 	sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
833 	sbp[0]->s_mtime = cpu_to_le64(ktime_get_real_seconds());
834 
835 skip_mount_setup:
836 	sbp[0]->s_state =
837 		cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
838 	/* synchronize sbp[1] with sbp[0] */
839 	if (sbp[1])
840 		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
841 	return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
842 }
843 
844 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
845 						 u64 pos, int blocksize,
846 						 struct buffer_head **pbh)
847 {
848 	unsigned long long sb_index = pos;
849 	unsigned long offset;
850 
851 	offset = do_div(sb_index, blocksize);
852 	*pbh = sb_bread(sb, sb_index);
853 	if (!*pbh)
854 		return NULL;
855 	return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
856 }
857 
858 int nilfs_store_magic_and_option(struct super_block *sb,
859 				 struct nilfs_super_block *sbp,
860 				 char *data)
861 {
862 	struct the_nilfs *nilfs = sb->s_fs_info;
863 
864 	sb->s_magic = le16_to_cpu(sbp->s_magic);
865 
866 	/* FS independent flags */
867 #ifdef NILFS_ATIME_DISABLE
868 	sb->s_flags |= SB_NOATIME;
869 #endif
870 
871 	nilfs_set_default_options(sb, sbp);
872 
873 	nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
874 	nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
875 	nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
876 	nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
877 
878 	return !parse_options(data, sb, 0) ? -EINVAL : 0;
879 }
880 
881 int nilfs_check_feature_compatibility(struct super_block *sb,
882 				      struct nilfs_super_block *sbp)
883 {
884 	__u64 features;
885 
886 	features = le64_to_cpu(sbp->s_feature_incompat) &
887 		~NILFS_FEATURE_INCOMPAT_SUPP;
888 	if (features) {
889 		nilfs_err(sb,
890 			  "couldn't mount because of unsupported optional features (%llx)",
891 			  (unsigned long long)features);
892 		return -EINVAL;
893 	}
894 	features = le64_to_cpu(sbp->s_feature_compat_ro) &
895 		~NILFS_FEATURE_COMPAT_RO_SUPP;
896 	if (!sb_rdonly(sb) && features) {
897 		nilfs_err(sb,
898 			  "couldn't mount RDWR because of unsupported optional features (%llx)",
899 			  (unsigned long long)features);
900 		return -EINVAL;
901 	}
902 	return 0;
903 }
904 
905 static int nilfs_get_root_dentry(struct super_block *sb,
906 				 struct nilfs_root *root,
907 				 struct dentry **root_dentry)
908 {
909 	struct inode *inode;
910 	struct dentry *dentry;
911 	int ret = 0;
912 
913 	inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
914 	if (IS_ERR(inode)) {
915 		ret = PTR_ERR(inode);
916 		nilfs_err(sb, "error %d getting root inode", ret);
917 		goto out;
918 	}
919 	if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
920 		iput(inode);
921 		nilfs_err(sb, "corrupt root inode");
922 		ret = -EINVAL;
923 		goto out;
924 	}
925 
926 	if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
927 		dentry = d_find_alias(inode);
928 		if (!dentry) {
929 			dentry = d_make_root(inode);
930 			if (!dentry) {
931 				ret = -ENOMEM;
932 				goto failed_dentry;
933 			}
934 		} else {
935 			iput(inode);
936 		}
937 	} else {
938 		dentry = d_obtain_root(inode);
939 		if (IS_ERR(dentry)) {
940 			ret = PTR_ERR(dentry);
941 			goto failed_dentry;
942 		}
943 	}
944 	*root_dentry = dentry;
945  out:
946 	return ret;
947 
948  failed_dentry:
949 	nilfs_err(sb, "error %d getting root dentry", ret);
950 	goto out;
951 }
952 
953 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
954 				 struct dentry **root_dentry)
955 {
956 	struct the_nilfs *nilfs = s->s_fs_info;
957 	struct nilfs_root *root;
958 	int ret;
959 
960 	mutex_lock(&nilfs->ns_snapshot_mount_mutex);
961 
962 	down_read(&nilfs->ns_segctor_sem);
963 	ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
964 	up_read(&nilfs->ns_segctor_sem);
965 	if (ret < 0) {
966 		ret = (ret == -ENOENT) ? -EINVAL : ret;
967 		goto out;
968 	} else if (!ret) {
969 		nilfs_err(s,
970 			  "The specified checkpoint is not a snapshot (checkpoint number=%llu)",
971 			  (unsigned long long)cno);
972 		ret = -EINVAL;
973 		goto out;
974 	}
975 
976 	ret = nilfs_attach_checkpoint(s, cno, false, &root);
977 	if (ret) {
978 		nilfs_err(s,
979 			  "error %d while loading snapshot (checkpoint number=%llu)",
980 			  ret, (unsigned long long)cno);
981 		goto out;
982 	}
983 	ret = nilfs_get_root_dentry(s, root, root_dentry);
984 	nilfs_put_root(root);
985  out:
986 	mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
987 	return ret;
988 }
989 
990 /**
991  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
992  * @root_dentry: root dentry of the tree to be shrunk
993  *
994  * This function returns true if the tree was in-use.
995  */
996 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
997 {
998 	shrink_dcache_parent(root_dentry);
999 	return d_count(root_dentry) > 1;
1000 }
1001 
1002 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1003 {
1004 	struct the_nilfs *nilfs = sb->s_fs_info;
1005 	struct nilfs_root *root;
1006 	struct inode *inode;
1007 	struct dentry *dentry;
1008 	int ret;
1009 
1010 	if (cno > nilfs->ns_cno)
1011 		return false;
1012 
1013 	if (cno >= nilfs_last_cno(nilfs))
1014 		return true;	/* protect recent checkpoints */
1015 
1016 	ret = false;
1017 	root = nilfs_lookup_root(nilfs, cno);
1018 	if (root) {
1019 		inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1020 		if (inode) {
1021 			dentry = d_find_alias(inode);
1022 			if (dentry) {
1023 				ret = nilfs_tree_is_busy(dentry);
1024 				dput(dentry);
1025 			}
1026 			iput(inode);
1027 		}
1028 		nilfs_put_root(root);
1029 	}
1030 	return ret;
1031 }
1032 
1033 /**
1034  * nilfs_fill_super() - initialize a super block instance
1035  * @sb: super_block
1036  * @data: mount options
1037  * @silent: silent mode flag
1038  *
1039  * This function is called exclusively by nilfs->ns_mount_mutex.
1040  * So, the recovery process is protected from other simultaneous mounts.
1041  */
1042 static int
1043 nilfs_fill_super(struct super_block *sb, void *data, int silent)
1044 {
1045 	struct the_nilfs *nilfs;
1046 	struct nilfs_root *fsroot;
1047 	__u64 cno;
1048 	int err;
1049 
1050 	nilfs = alloc_nilfs(sb);
1051 	if (!nilfs)
1052 		return -ENOMEM;
1053 
1054 	sb->s_fs_info = nilfs;
1055 
1056 	err = init_nilfs(nilfs, sb, (char *)data);
1057 	if (err)
1058 		goto failed_nilfs;
1059 
1060 	sb->s_op = &nilfs_sops;
1061 	sb->s_export_op = &nilfs_export_ops;
1062 	sb->s_root = NULL;
1063 	sb->s_time_gran = 1;
1064 	sb->s_max_links = NILFS_LINK_MAX;
1065 
1066 	sb->s_bdi = bdi_get(sb->s_bdev->bd_disk->bdi);
1067 
1068 	err = load_nilfs(nilfs, sb);
1069 	if (err)
1070 		goto failed_nilfs;
1071 
1072 	cno = nilfs_last_cno(nilfs);
1073 	err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1074 	if (err) {
1075 		nilfs_err(sb,
1076 			  "error %d while loading last checkpoint (checkpoint number=%llu)",
1077 			  err, (unsigned long long)cno);
1078 		goto failed_unload;
1079 	}
1080 
1081 	if (!sb_rdonly(sb)) {
1082 		err = nilfs_attach_log_writer(sb, fsroot);
1083 		if (err)
1084 			goto failed_checkpoint;
1085 	}
1086 
1087 	err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1088 	if (err)
1089 		goto failed_segctor;
1090 
1091 	nilfs_put_root(fsroot);
1092 
1093 	if (!sb_rdonly(sb)) {
1094 		down_write(&nilfs->ns_sem);
1095 		nilfs_setup_super(sb, true);
1096 		up_write(&nilfs->ns_sem);
1097 	}
1098 
1099 	return 0;
1100 
1101  failed_segctor:
1102 	nilfs_detach_log_writer(sb);
1103 
1104  failed_checkpoint:
1105 	nilfs_put_root(fsroot);
1106 
1107  failed_unload:
1108 	iput(nilfs->ns_sufile);
1109 	iput(nilfs->ns_cpfile);
1110 	iput(nilfs->ns_dat);
1111 
1112  failed_nilfs:
1113 	destroy_nilfs(nilfs);
1114 	return err;
1115 }
1116 
1117 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1118 {
1119 	struct the_nilfs *nilfs = sb->s_fs_info;
1120 	unsigned long old_sb_flags;
1121 	unsigned long old_mount_opt;
1122 	int err;
1123 
1124 	sync_filesystem(sb);
1125 	old_sb_flags = sb->s_flags;
1126 	old_mount_opt = nilfs->ns_mount_opt;
1127 
1128 	if (!parse_options(data, sb, 1)) {
1129 		err = -EINVAL;
1130 		goto restore_opts;
1131 	}
1132 	sb->s_flags = (sb->s_flags & ~SB_POSIXACL);
1133 
1134 	err = -EINVAL;
1135 
1136 	if (!nilfs_valid_fs(nilfs)) {
1137 		nilfs_warn(sb,
1138 			   "couldn't remount because the filesystem is in an incomplete recovery state");
1139 		goto restore_opts;
1140 	}
1141 
1142 	if ((bool)(*flags & SB_RDONLY) == sb_rdonly(sb))
1143 		goto out;
1144 	if (*flags & SB_RDONLY) {
1145 		sb->s_flags |= SB_RDONLY;
1146 
1147 		/*
1148 		 * Remounting a valid RW partition RDONLY, so set
1149 		 * the RDONLY flag and then mark the partition as valid again.
1150 		 */
1151 		down_write(&nilfs->ns_sem);
1152 		nilfs_cleanup_super(sb);
1153 		up_write(&nilfs->ns_sem);
1154 	} else {
1155 		__u64 features;
1156 		struct nilfs_root *root;
1157 
1158 		/*
1159 		 * Mounting a RDONLY partition read-write, so reread and
1160 		 * store the current valid flag.  (It may have been changed
1161 		 * by fsck since we originally mounted the partition.)
1162 		 */
1163 		down_read(&nilfs->ns_sem);
1164 		features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1165 			~NILFS_FEATURE_COMPAT_RO_SUPP;
1166 		up_read(&nilfs->ns_sem);
1167 		if (features) {
1168 			nilfs_warn(sb,
1169 				   "couldn't remount RDWR because of unsupported optional features (%llx)",
1170 				   (unsigned long long)features);
1171 			err = -EROFS;
1172 			goto restore_opts;
1173 		}
1174 
1175 		sb->s_flags &= ~SB_RDONLY;
1176 
1177 		root = NILFS_I(d_inode(sb->s_root))->i_root;
1178 		err = nilfs_attach_log_writer(sb, root);
1179 		if (err)
1180 			goto restore_opts;
1181 
1182 		down_write(&nilfs->ns_sem);
1183 		nilfs_setup_super(sb, true);
1184 		up_write(&nilfs->ns_sem);
1185 	}
1186  out:
1187 	return 0;
1188 
1189  restore_opts:
1190 	sb->s_flags = old_sb_flags;
1191 	nilfs->ns_mount_opt = old_mount_opt;
1192 	return err;
1193 }
1194 
1195 struct nilfs_super_data {
1196 	struct block_device *bdev;
1197 	__u64 cno;
1198 	int flags;
1199 };
1200 
1201 static int nilfs_parse_snapshot_option(const char *option,
1202 				       const substring_t *arg,
1203 				       struct nilfs_super_data *sd)
1204 {
1205 	unsigned long long val;
1206 	const char *msg = NULL;
1207 	int err;
1208 
1209 	if (!(sd->flags & SB_RDONLY)) {
1210 		msg = "read-only option is not specified";
1211 		goto parse_error;
1212 	}
1213 
1214 	err = kstrtoull(arg->from, 0, &val);
1215 	if (err) {
1216 		if (err == -ERANGE)
1217 			msg = "too large checkpoint number";
1218 		else
1219 			msg = "malformed argument";
1220 		goto parse_error;
1221 	} else if (val == 0) {
1222 		msg = "invalid checkpoint number 0";
1223 		goto parse_error;
1224 	}
1225 	sd->cno = val;
1226 	return 0;
1227 
1228 parse_error:
1229 	nilfs_err(NULL, "invalid option \"%s\": %s", option, msg);
1230 	return 1;
1231 }
1232 
1233 /**
1234  * nilfs_identify - pre-read mount options needed to identify mount instance
1235  * @data: mount options
1236  * @sd: nilfs_super_data
1237  */
1238 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1239 {
1240 	char *p, *options = data;
1241 	substring_t args[MAX_OPT_ARGS];
1242 	int token;
1243 	int ret = 0;
1244 
1245 	do {
1246 		p = strsep(&options, ",");
1247 		if (p != NULL && *p) {
1248 			token = match_token(p, tokens, args);
1249 			if (token == Opt_snapshot)
1250 				ret = nilfs_parse_snapshot_option(p, &args[0],
1251 								  sd);
1252 		}
1253 		if (!options)
1254 			break;
1255 		BUG_ON(options == data);
1256 		*(options - 1) = ',';
1257 	} while (!ret);
1258 	return ret;
1259 }
1260 
1261 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1262 {
1263 	s->s_bdev = data;
1264 	s->s_dev = s->s_bdev->bd_dev;
1265 	return 0;
1266 }
1267 
1268 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1269 {
1270 	return (void *)s->s_bdev == data;
1271 }
1272 
1273 static struct dentry *
1274 nilfs_mount(struct file_system_type *fs_type, int flags,
1275 	     const char *dev_name, void *data)
1276 {
1277 	struct nilfs_super_data sd;
1278 	struct super_block *s;
1279 	fmode_t mode = FMODE_READ | FMODE_EXCL;
1280 	struct dentry *root_dentry;
1281 	int err, s_new = false;
1282 
1283 	if (!(flags & SB_RDONLY))
1284 		mode |= FMODE_WRITE;
1285 
1286 	sd.bdev = blkdev_get_by_path(dev_name, mode, fs_type);
1287 	if (IS_ERR(sd.bdev))
1288 		return ERR_CAST(sd.bdev);
1289 
1290 	sd.cno = 0;
1291 	sd.flags = flags;
1292 	if (nilfs_identify((char *)data, &sd)) {
1293 		err = -EINVAL;
1294 		goto failed;
1295 	}
1296 
1297 	/*
1298 	 * once the super is inserted into the list by sget, s_umount
1299 	 * will protect the lockfs code from trying to start a snapshot
1300 	 * while we are mounting
1301 	 */
1302 	mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
1303 	if (sd.bdev->bd_fsfreeze_count > 0) {
1304 		mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1305 		err = -EBUSY;
1306 		goto failed;
1307 	}
1308 	s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
1309 		 sd.bdev);
1310 	mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1311 	if (IS_ERR(s)) {
1312 		err = PTR_ERR(s);
1313 		goto failed;
1314 	}
1315 
1316 	if (!s->s_root) {
1317 		s_new = true;
1318 
1319 		/* New superblock instance created */
1320 		s->s_mode = mode;
1321 		snprintf(s->s_id, sizeof(s->s_id), "%pg", sd.bdev);
1322 		sb_set_blocksize(s, block_size(sd.bdev));
1323 
1324 		err = nilfs_fill_super(s, data, flags & SB_SILENT ? 1 : 0);
1325 		if (err)
1326 			goto failed_super;
1327 
1328 		s->s_flags |= SB_ACTIVE;
1329 	} else if (!sd.cno) {
1330 		if (nilfs_tree_is_busy(s->s_root)) {
1331 			if ((flags ^ s->s_flags) & SB_RDONLY) {
1332 				nilfs_err(s,
1333 					  "the device already has a %s mount.",
1334 					  sb_rdonly(s) ? "read-only" : "read/write");
1335 				err = -EBUSY;
1336 				goto failed_super;
1337 			}
1338 		} else {
1339 			/*
1340 			 * Try remount to setup mount states if the current
1341 			 * tree is not mounted and only snapshots use this sb.
1342 			 */
1343 			err = nilfs_remount(s, &flags, data);
1344 			if (err)
1345 				goto failed_super;
1346 		}
1347 	}
1348 
1349 	if (sd.cno) {
1350 		err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1351 		if (err)
1352 			goto failed_super;
1353 	} else {
1354 		root_dentry = dget(s->s_root);
1355 	}
1356 
1357 	if (!s_new)
1358 		blkdev_put(sd.bdev, mode);
1359 
1360 	return root_dentry;
1361 
1362  failed_super:
1363 	deactivate_locked_super(s);
1364 
1365  failed:
1366 	if (!s_new)
1367 		blkdev_put(sd.bdev, mode);
1368 	return ERR_PTR(err);
1369 }
1370 
1371 struct file_system_type nilfs_fs_type = {
1372 	.owner    = THIS_MODULE,
1373 	.name     = "nilfs2",
1374 	.mount    = nilfs_mount,
1375 	.kill_sb  = kill_block_super,
1376 	.fs_flags = FS_REQUIRES_DEV,
1377 };
1378 MODULE_ALIAS_FS("nilfs2");
1379 
1380 static void nilfs_inode_init_once(void *obj)
1381 {
1382 	struct nilfs_inode_info *ii = obj;
1383 
1384 	INIT_LIST_HEAD(&ii->i_dirty);
1385 #ifdef CONFIG_NILFS_XATTR
1386 	init_rwsem(&ii->xattr_sem);
1387 #endif
1388 	inode_init_once(&ii->vfs_inode);
1389 }
1390 
1391 static void nilfs_segbuf_init_once(void *obj)
1392 {
1393 	memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1394 }
1395 
1396 static void nilfs_destroy_cachep(void)
1397 {
1398 	/*
1399 	 * Make sure all delayed rcu free inodes are flushed before we
1400 	 * destroy cache.
1401 	 */
1402 	rcu_barrier();
1403 
1404 	kmem_cache_destroy(nilfs_inode_cachep);
1405 	kmem_cache_destroy(nilfs_transaction_cachep);
1406 	kmem_cache_destroy(nilfs_segbuf_cachep);
1407 	kmem_cache_destroy(nilfs_btree_path_cache);
1408 }
1409 
1410 static int __init nilfs_init_cachep(void)
1411 {
1412 	nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1413 			sizeof(struct nilfs_inode_info), 0,
1414 			SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
1415 			nilfs_inode_init_once);
1416 	if (!nilfs_inode_cachep)
1417 		goto fail;
1418 
1419 	nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1420 			sizeof(struct nilfs_transaction_info), 0,
1421 			SLAB_RECLAIM_ACCOUNT, NULL);
1422 	if (!nilfs_transaction_cachep)
1423 		goto fail;
1424 
1425 	nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1426 			sizeof(struct nilfs_segment_buffer), 0,
1427 			SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1428 	if (!nilfs_segbuf_cachep)
1429 		goto fail;
1430 
1431 	nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1432 			sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1433 			0, 0, NULL);
1434 	if (!nilfs_btree_path_cache)
1435 		goto fail;
1436 
1437 	return 0;
1438 
1439 fail:
1440 	nilfs_destroy_cachep();
1441 	return -ENOMEM;
1442 }
1443 
1444 static int __init init_nilfs_fs(void)
1445 {
1446 	int err;
1447 
1448 	err = nilfs_init_cachep();
1449 	if (err)
1450 		goto fail;
1451 
1452 	err = nilfs_sysfs_init();
1453 	if (err)
1454 		goto free_cachep;
1455 
1456 	err = register_filesystem(&nilfs_fs_type);
1457 	if (err)
1458 		goto deinit_sysfs_entry;
1459 
1460 	printk(KERN_INFO "NILFS version 2 loaded\n");
1461 	return 0;
1462 
1463 deinit_sysfs_entry:
1464 	nilfs_sysfs_exit();
1465 free_cachep:
1466 	nilfs_destroy_cachep();
1467 fail:
1468 	return err;
1469 }
1470 
1471 static void __exit exit_nilfs_fs(void)
1472 {
1473 	nilfs_destroy_cachep();
1474 	nilfs_sysfs_exit();
1475 	unregister_filesystem(&nilfs_fs_type);
1476 }
1477 
1478 module_init(init_nilfs_fs)
1479 module_exit(exit_nilfs_fs)
1480