2 * the_nilfs.c - the_nilfs shared structure.
4 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * Written by Ryusuke Konishi <ryusuke@osrg.net>
24 #include <linux/buffer_head.h>
25 #include <linux/slab.h>
26 #include <linux/blkdev.h>
27 #include <linux/backing-dev.h>
28 #include <linux/crc32.h>
39 static LIST_HEAD(nilfs_objects
);
40 static DEFINE_SPINLOCK(nilfs_lock
);
42 void nilfs_set_last_segment(struct the_nilfs
*nilfs
,
43 sector_t start_blocknr
, u64 seq
, __u64 cno
)
45 spin_lock(&nilfs
->ns_last_segment_lock
);
46 nilfs
->ns_last_pseg
= start_blocknr
;
47 nilfs
->ns_last_seq
= seq
;
48 nilfs
->ns_last_cno
= cno
;
49 spin_unlock(&nilfs
->ns_last_segment_lock
);
53 * alloc_nilfs - allocate the_nilfs structure
54 * @bdev: block device to which the_nilfs is related
56 * alloc_nilfs() allocates memory for the_nilfs and
57 * initializes its reference count and locks.
59 * Return Value: On success, pointer to the_nilfs is returned.
60 * On error, NULL is returned.
62 static struct the_nilfs
*alloc_nilfs(struct block_device
*bdev
)
64 struct the_nilfs
*nilfs
;
66 nilfs
= kzalloc(sizeof(*nilfs
), GFP_KERNEL
);
70 nilfs
->ns_bdev
= bdev
;
71 atomic_set(&nilfs
->ns_count
, 1);
72 atomic_set(&nilfs
->ns_writer_refcount
, -1);
73 atomic_set(&nilfs
->ns_ndirtyblks
, 0);
74 init_rwsem(&nilfs
->ns_sem
);
75 mutex_init(&nilfs
->ns_writer_mutex
);
76 INIT_LIST_HEAD(&nilfs
->ns_list
);
77 INIT_LIST_HEAD(&nilfs
->ns_supers
);
78 spin_lock_init(&nilfs
->ns_last_segment_lock
);
79 nilfs
->ns_gc_inodes_h
= NULL
;
80 init_rwsem(&nilfs
->ns_segctor_sem
);
86 * find_or_create_nilfs - find or create nilfs object
87 * @bdev: block device to which the_nilfs is related
89 * find_nilfs() looks up an existent nilfs object created on the
90 * device and gets the reference count of the object. If no nilfs object
91 * is found on the device, a new nilfs object is allocated.
93 * Return Value: On success, pointer to the nilfs object is returned.
94 * On error, NULL is returned.
96 struct the_nilfs
*find_or_create_nilfs(struct block_device
*bdev
)
98 struct the_nilfs
*nilfs
, *new = NULL
;
101 spin_lock(&nilfs_lock
);
102 list_for_each_entry(nilfs
, &nilfs_objects
, ns_list
) {
103 if (nilfs
->ns_bdev
== bdev
) {
105 spin_unlock(&nilfs_lock
);
108 return nilfs
; /* existing object */
112 list_add_tail(&new->ns_list
, &nilfs_objects
);
113 spin_unlock(&nilfs_lock
);
114 return new; /* new object */
116 spin_unlock(&nilfs_lock
);
118 new = alloc_nilfs(bdev
);
121 return NULL
; /* insufficient memory */
125 * put_nilfs - release a reference to the_nilfs
126 * @nilfs: the_nilfs structure to be released
128 * put_nilfs() decrements a reference counter of the_nilfs.
129 * If the reference count reaches zero, the_nilfs is freed.
131 void put_nilfs(struct the_nilfs
*nilfs
)
133 spin_lock(&nilfs_lock
);
134 if (!atomic_dec_and_test(&nilfs
->ns_count
)) {
135 spin_unlock(&nilfs_lock
);
138 list_del_init(&nilfs
->ns_list
);
139 spin_unlock(&nilfs_lock
);
142 * Increment of ns_count never occurs below because the caller
143 * of get_nilfs() holds at least one reference to the_nilfs.
144 * Thus its exclusion control is not required here.
148 if (nilfs_loaded(nilfs
)) {
149 nilfs_mdt_clear(nilfs
->ns_sufile
);
150 nilfs_mdt_destroy(nilfs
->ns_sufile
);
151 nilfs_mdt_clear(nilfs
->ns_cpfile
);
152 nilfs_mdt_destroy(nilfs
->ns_cpfile
);
153 nilfs_mdt_clear(nilfs
->ns_dat
);
154 nilfs_mdt_destroy(nilfs
->ns_dat
);
155 /* XXX: how and when to clear nilfs->ns_gc_dat? */
156 nilfs_mdt_destroy(nilfs
->ns_gc_dat
);
158 if (nilfs_init(nilfs
)) {
159 nilfs_destroy_gccache(nilfs
);
160 brelse(nilfs
->ns_sbh
[0]);
161 brelse(nilfs
->ns_sbh
[1]);
166 static int nilfs_load_super_root(struct the_nilfs
*nilfs
,
167 struct nilfs_sb_info
*sbi
, sector_t sr_block
)
169 static struct lock_class_key dat_lock_key
;
170 struct buffer_head
*bh_sr
;
171 struct nilfs_super_root
*raw_sr
;
172 struct nilfs_super_block
**sbp
= nilfs
->ns_sbp
;
173 unsigned dat_entry_size
, segment_usage_size
, checkpoint_size
;
177 err
= nilfs_read_super_root_block(sbi
->s_super
, sr_block
, &bh_sr
, 1);
181 down_read(&nilfs
->ns_sem
);
182 dat_entry_size
= le16_to_cpu(sbp
[0]->s_dat_entry_size
);
183 checkpoint_size
= le16_to_cpu(sbp
[0]->s_checkpoint_size
);
184 segment_usage_size
= le16_to_cpu(sbp
[0]->s_segment_usage_size
);
185 up_read(&nilfs
->ns_sem
);
187 inode_size
= nilfs
->ns_inode_size
;
190 nilfs
->ns_dat
= nilfs_mdt_new(
191 nilfs
, NULL
, NILFS_DAT_INO
, NILFS_DAT_GFP
);
192 if (unlikely(!nilfs
->ns_dat
))
195 nilfs
->ns_gc_dat
= nilfs_mdt_new(
196 nilfs
, NULL
, NILFS_DAT_INO
, NILFS_DAT_GFP
);
197 if (unlikely(!nilfs
->ns_gc_dat
))
200 nilfs
->ns_cpfile
= nilfs_mdt_new(
201 nilfs
, NULL
, NILFS_CPFILE_INO
, NILFS_CPFILE_GFP
);
202 if (unlikely(!nilfs
->ns_cpfile
))
205 nilfs
->ns_sufile
= nilfs_mdt_new(
206 nilfs
, NULL
, NILFS_SUFILE_INO
, NILFS_SUFILE_GFP
);
207 if (unlikely(!nilfs
->ns_sufile
))
210 err
= nilfs_palloc_init_blockgroup(nilfs
->ns_dat
, dat_entry_size
);
214 err
= nilfs_palloc_init_blockgroup(nilfs
->ns_gc_dat
, dat_entry_size
);
218 lockdep_set_class(&NILFS_MDT(nilfs
->ns_dat
)->mi_sem
, &dat_lock_key
);
219 lockdep_set_class(&NILFS_MDT(nilfs
->ns_gc_dat
)->mi_sem
, &dat_lock_key
);
221 nilfs_mdt_set_shadow(nilfs
->ns_dat
, nilfs
->ns_gc_dat
);
222 nilfs_mdt_set_entry_size(nilfs
->ns_cpfile
, checkpoint_size
,
223 sizeof(struct nilfs_cpfile_header
));
224 nilfs_mdt_set_entry_size(nilfs
->ns_sufile
, segment_usage_size
,
225 sizeof(struct nilfs_sufile_header
));
227 err
= nilfs_mdt_read_inode_direct(
228 nilfs
->ns_dat
, bh_sr
, NILFS_SR_DAT_OFFSET(inode_size
));
232 err
= nilfs_mdt_read_inode_direct(
233 nilfs
->ns_cpfile
, bh_sr
, NILFS_SR_CPFILE_OFFSET(inode_size
));
237 err
= nilfs_mdt_read_inode_direct(
238 nilfs
->ns_sufile
, bh_sr
, NILFS_SR_SUFILE_OFFSET(inode_size
));
242 raw_sr
= (struct nilfs_super_root
*)bh_sr
->b_data
;
243 nilfs
->ns_nongc_ctime
= le64_to_cpu(raw_sr
->sr_nongc_ctime
);
250 nilfs_mdt_destroy(nilfs
->ns_sufile
);
253 nilfs_mdt_destroy(nilfs
->ns_cpfile
);
256 nilfs_mdt_destroy(nilfs
->ns_gc_dat
);
259 nilfs_mdt_destroy(nilfs
->ns_dat
);
263 static void nilfs_init_recovery_info(struct nilfs_recovery_info
*ri
)
265 memset(ri
, 0, sizeof(*ri
));
266 INIT_LIST_HEAD(&ri
->ri_used_segments
);
269 static void nilfs_clear_recovery_info(struct nilfs_recovery_info
*ri
)
271 nilfs_dispose_segment_list(&ri
->ri_used_segments
);
275 * load_nilfs - load and recover the nilfs
276 * @nilfs: the_nilfs structure to be released
277 * @sbi: nilfs_sb_info used to recover past segment
279 * load_nilfs() searches and load the latest super root,
280 * attaches the last segment, and does recovery if needed.
281 * The caller must call this exclusively for simultaneous mounts.
283 int load_nilfs(struct the_nilfs
*nilfs
, struct nilfs_sb_info
*sbi
)
285 struct nilfs_recovery_info ri
;
286 unsigned int s_flags
= sbi
->s_super
->s_flags
;
287 int really_read_only
= bdev_read_only(nilfs
->ns_bdev
);
291 nilfs_init_recovery_info(&ri
);
293 down_write(&nilfs
->ns_sem
);
294 valid_fs
= (nilfs
->ns_mount_state
& NILFS_VALID_FS
);
295 up_write(&nilfs
->ns_sem
);
297 if (!valid_fs
&& (s_flags
& MS_RDONLY
)) {
298 printk(KERN_INFO
"NILFS: INFO: recovery "
299 "required for readonly filesystem.\n");
300 if (really_read_only
) {
301 printk(KERN_ERR
"NILFS: write access "
302 "unavailable, cannot proceed.\n");
306 printk(KERN_INFO
"NILFS: write access will "
307 "be enabled during recovery.\n");
308 sbi
->s_super
->s_flags
&= ~MS_RDONLY
;
311 err
= nilfs_search_super_root(nilfs
, sbi
, &ri
);
313 printk(KERN_ERR
"NILFS: error searching super root.\n");
317 err
= nilfs_load_super_root(nilfs
, sbi
, ri
.ri_super_root
);
319 printk(KERN_ERR
"NILFS: error loading super root.\n");
324 err
= nilfs_recover_logical_segments(nilfs
, sbi
, &ri
);
326 nilfs_mdt_destroy(nilfs
->ns_cpfile
);
327 nilfs_mdt_destroy(nilfs
->ns_sufile
);
328 nilfs_mdt_destroy(nilfs
->ns_dat
);
331 if (ri
.ri_need_recovery
== NILFS_RECOVERY_SR_UPDATED
)
332 sbi
->s_super
->s_dirt
= 1;
335 set_nilfs_loaded(nilfs
);
338 nilfs_clear_recovery_info(&ri
);
339 sbi
->s_super
->s_flags
= s_flags
;
343 static unsigned long long nilfs_max_size(unsigned int blkbits
)
345 unsigned int max_bits
;
346 unsigned long long res
= MAX_LFS_FILESIZE
; /* page cache limit */
348 max_bits
= blkbits
+ NILFS_BMAP_KEY_BIT
; /* bmap size limit */
350 res
= min_t(unsigned long long, res
, (1ULL << max_bits
) - 1);
354 static int nilfs_store_disk_layout(struct the_nilfs
*nilfs
,
355 struct nilfs_super_block
*sbp
)
357 if (le32_to_cpu(sbp
->s_rev_level
) != NILFS_CURRENT_REV
) {
358 printk(KERN_ERR
"NILFS: revision mismatch "
359 "(superblock rev.=%d.%d, current rev.=%d.%d). "
360 "Please check the version of mkfs.nilfs.\n",
361 le32_to_cpu(sbp
->s_rev_level
),
362 le16_to_cpu(sbp
->s_minor_rev_level
),
363 NILFS_CURRENT_REV
, NILFS_MINOR_REV
);
366 nilfs
->ns_sbsize
= le16_to_cpu(sbp
->s_bytes
);
367 if (nilfs
->ns_sbsize
> BLOCK_SIZE
)
370 nilfs
->ns_inode_size
= le16_to_cpu(sbp
->s_inode_size
);
371 nilfs
->ns_first_ino
= le32_to_cpu(sbp
->s_first_ino
);
373 nilfs
->ns_blocks_per_segment
= le32_to_cpu(sbp
->s_blocks_per_segment
);
374 if (nilfs
->ns_blocks_per_segment
< NILFS_SEG_MIN_BLOCKS
) {
375 printk(KERN_ERR
"NILFS: too short segment. \n");
379 nilfs
->ns_first_data_block
= le64_to_cpu(sbp
->s_first_data_block
);
380 nilfs
->ns_nsegments
= le64_to_cpu(sbp
->s_nsegments
);
381 nilfs
->ns_r_segments_percentage
=
382 le32_to_cpu(sbp
->s_r_segments_percentage
);
384 max_t(unsigned long, NILFS_MIN_NRSVSEGS
,
385 DIV_ROUND_UP(nilfs
->ns_nsegments
*
386 nilfs
->ns_r_segments_percentage
, 100));
387 nilfs
->ns_crc_seed
= le32_to_cpu(sbp
->s_crc_seed
);
391 static int nilfs_valid_sb(struct nilfs_super_block
*sbp
)
393 static unsigned char sum
[4];
394 const int sumoff
= offsetof(struct nilfs_super_block
, s_sum
);
398 if (!sbp
|| le16_to_cpu(sbp
->s_magic
) != NILFS_SUPER_MAGIC
)
400 bytes
= le16_to_cpu(sbp
->s_bytes
);
401 if (bytes
> BLOCK_SIZE
)
403 crc
= crc32_le(le32_to_cpu(sbp
->s_crc_seed
), (unsigned char *)sbp
,
405 crc
= crc32_le(crc
, sum
, 4);
406 crc
= crc32_le(crc
, (unsigned char *)sbp
+ sumoff
+ 4,
408 return crc
== le32_to_cpu(sbp
->s_sum
);
411 static int nilfs_sb2_bad_offset(struct nilfs_super_block
*sbp
, u64 offset
)
413 return offset
< ((le64_to_cpu(sbp
->s_nsegments
) *
414 le32_to_cpu(sbp
->s_blocks_per_segment
)) <<
415 (le32_to_cpu(sbp
->s_log_block_size
) + 10));
418 static void nilfs_release_super_block(struct the_nilfs
*nilfs
)
422 for (i
= 0; i
< 2; i
++) {
423 if (nilfs
->ns_sbp
[i
]) {
424 brelse(nilfs
->ns_sbh
[i
]);
425 nilfs
->ns_sbh
[i
] = NULL
;
426 nilfs
->ns_sbp
[i
] = NULL
;
431 void nilfs_fall_back_super_block(struct the_nilfs
*nilfs
)
433 brelse(nilfs
->ns_sbh
[0]);
434 nilfs
->ns_sbh
[0] = nilfs
->ns_sbh
[1];
435 nilfs
->ns_sbp
[0] = nilfs
->ns_sbp
[1];
436 nilfs
->ns_sbh
[1] = NULL
;
437 nilfs
->ns_sbp
[1] = NULL
;
440 void nilfs_swap_super_block(struct the_nilfs
*nilfs
)
442 struct buffer_head
*tsbh
= nilfs
->ns_sbh
[0];
443 struct nilfs_super_block
*tsbp
= nilfs
->ns_sbp
[0];
445 nilfs
->ns_sbh
[0] = nilfs
->ns_sbh
[1];
446 nilfs
->ns_sbp
[0] = nilfs
->ns_sbp
[1];
447 nilfs
->ns_sbh
[1] = tsbh
;
448 nilfs
->ns_sbp
[1] = tsbp
;
451 static int nilfs_load_super_block(struct the_nilfs
*nilfs
,
452 struct super_block
*sb
, int blocksize
,
453 struct nilfs_super_block
**sbpp
)
455 struct nilfs_super_block
**sbp
= nilfs
->ns_sbp
;
456 struct buffer_head
**sbh
= nilfs
->ns_sbh
;
457 u64 sb2off
= NILFS_SB2_OFFSET_BYTES(nilfs
->ns_bdev
->bd_inode
->i_size
);
458 int valid
[2], swp
= 0;
460 sbp
[0] = nilfs_read_super_block(sb
, NILFS_SB_OFFSET_BYTES
, blocksize
,
462 sbp
[1] = nilfs_read_super_block(sb
, sb2off
, blocksize
, &sbh
[1]);
466 printk(KERN_ERR
"NILFS: unable to read superblock\n");
470 "NILFS warning: unable to read primary superblock\n");
473 "NILFS warning: unable to read secondary superblock\n");
475 valid
[0] = nilfs_valid_sb(sbp
[0]);
476 valid
[1] = nilfs_valid_sb(sbp
[1]);
479 le64_to_cpu(sbp
[1]->s_wtime
) > le64_to_cpu(sbp
[0]->s_wtime
));
481 if (valid
[swp
] && nilfs_sb2_bad_offset(sbp
[swp
], sb2off
)) {
488 nilfs_release_super_block(nilfs
);
489 printk(KERN_ERR
"NILFS: Can't find nilfs on dev %s.\n",
495 printk(KERN_WARNING
"NILFS warning: broken superblock. "
496 "using spare superblock.\n");
497 nilfs_swap_super_block(nilfs
);
500 nilfs
->ns_sbwtime
[0] = le64_to_cpu(sbp
[0]->s_wtime
);
501 nilfs
->ns_sbwtime
[1] = valid
[!swp
] ? le64_to_cpu(sbp
[1]->s_wtime
) : 0;
502 nilfs
->ns_prot_seq
= le64_to_cpu(sbp
[valid
[1] & !swp
]->s_last_seq
);
508 * init_nilfs - initialize a NILFS instance.
509 * @nilfs: the_nilfs structure
510 * @sbi: nilfs_sb_info
512 * @data: mount options
514 * init_nilfs() performs common initialization per block device (e.g.
515 * reading the super block, getting disk layout information, initializing
516 * shared fields in the_nilfs). It takes on some portion of the jobs
517 * typically done by a fill_super() routine. This division arises from
518 * the nature that multiple NILFS instances may be simultaneously
519 * mounted on a device.
520 * For multiple mounts on the same device, only the first mount
521 * invokes these tasks.
523 * Return Value: On success, 0 is returned. On error, a negative error
526 int init_nilfs(struct the_nilfs
*nilfs
, struct nilfs_sb_info
*sbi
, char *data
)
528 struct super_block
*sb
= sbi
->s_super
;
529 struct nilfs_super_block
*sbp
;
530 struct backing_dev_info
*bdi
;
534 down_write(&nilfs
->ns_sem
);
535 if (nilfs_init(nilfs
)) {
536 /* Load values from existing the_nilfs */
537 sbp
= nilfs
->ns_sbp
[0];
538 err
= nilfs_store_magic_and_option(sb
, sbp
, data
);
542 blocksize
= BLOCK_SIZE
<< le32_to_cpu(sbp
->s_log_block_size
);
543 if (sb
->s_blocksize
!= blocksize
&&
544 !sb_set_blocksize(sb
, blocksize
)) {
545 printk(KERN_ERR
"NILFS: blocksize %d unfit to device\n",
549 sb
->s_maxbytes
= nilfs_max_size(sb
->s_blocksize_bits
);
553 blocksize
= sb_min_blocksize(sb
, BLOCK_SIZE
);
555 printk(KERN_ERR
"NILFS: unable to set blocksize\n");
559 err
= nilfs_load_super_block(nilfs
, sb
, blocksize
, &sbp
);
563 err
= nilfs_store_magic_and_option(sb
, sbp
, data
);
567 blocksize
= BLOCK_SIZE
<< le32_to_cpu(sbp
->s_log_block_size
);
568 if (sb
->s_blocksize
!= blocksize
) {
569 int hw_blocksize
= bdev_logical_block_size(sb
->s_bdev
);
571 if (blocksize
< hw_blocksize
) {
573 "NILFS: blocksize %d too small for device "
574 "(sector-size = %d).\n",
575 blocksize
, hw_blocksize
);
579 nilfs_release_super_block(nilfs
);
580 sb_set_blocksize(sb
, blocksize
);
582 err
= nilfs_load_super_block(nilfs
, sb
, blocksize
, &sbp
);
585 /* not failed_sbh; sbh is released automatically
586 when reloading fails. */
588 nilfs
->ns_blocksize_bits
= sb
->s_blocksize_bits
;
590 err
= nilfs_store_disk_layout(nilfs
, sbp
);
594 sb
->s_maxbytes
= nilfs_max_size(sb
->s_blocksize_bits
);
596 nilfs
->ns_mount_state
= le16_to_cpu(sbp
->s_state
);
598 bdi
= nilfs
->ns_bdev
->bd_inode_backing_dev_info
;
600 bdi
= nilfs
->ns_bdev
->bd_inode
->i_mapping
->backing_dev_info
;
601 nilfs
->ns_bdi
= bdi
? : &default_backing_dev_info
;
603 /* Finding last segment */
604 nilfs
->ns_last_pseg
= le64_to_cpu(sbp
->s_last_pseg
);
605 nilfs
->ns_last_cno
= le64_to_cpu(sbp
->s_last_cno
);
606 nilfs
->ns_last_seq
= le64_to_cpu(sbp
->s_last_seq
);
608 nilfs
->ns_seg_seq
= nilfs
->ns_last_seq
;
610 nilfs_get_segnum_of_block(nilfs
, nilfs
->ns_last_pseg
);
611 nilfs
->ns_cno
= nilfs
->ns_last_cno
+ 1;
612 if (nilfs
->ns_segnum
>= nilfs
->ns_nsegments
) {
613 printk(KERN_ERR
"NILFS invalid last segment number.\n");
618 nilfs
->ns_free_segments_count
=
619 nilfs
->ns_nsegments
- (nilfs
->ns_segnum
+ 1);
621 /* Initialize gcinode cache */
622 err
= nilfs_init_gccache(nilfs
);
626 set_nilfs_init(nilfs
);
629 up_write(&nilfs
->ns_sem
);
633 nilfs_release_super_block(nilfs
);
637 int nilfs_count_free_blocks(struct the_nilfs
*nilfs
, sector_t
*nblocks
)
639 struct inode
*dat
= nilfs_dat_inode(nilfs
);
640 unsigned long ncleansegs
;
643 down_read(&NILFS_MDT(dat
)->mi_sem
); /* XXX */
644 err
= nilfs_sufile_get_ncleansegs(nilfs
->ns_sufile
, &ncleansegs
);
645 up_read(&NILFS_MDT(dat
)->mi_sem
); /* XXX */
647 *nblocks
= (sector_t
)ncleansegs
* nilfs
->ns_blocks_per_segment
;
651 int nilfs_near_disk_full(struct the_nilfs
*nilfs
)
653 struct inode
*sufile
= nilfs
->ns_sufile
;
654 unsigned long ncleansegs
, nincsegs
;
657 ret
= nilfs_sufile_get_ncleansegs(sufile
, &ncleansegs
);
659 nincsegs
= atomic_read(&nilfs
->ns_ndirtyblks
) /
660 nilfs
->ns_blocks_per_segment
+ 1;
661 if (ncleansegs
<= nilfs
->ns_nrsvsegs
+ nincsegs
)
668 * nilfs_find_sbinfo - find existing nilfs_sb_info structure
669 * @nilfs: nilfs object
670 * @rw_mount: mount type (non-zero value for read/write mount)
671 * @cno: checkpoint number (zero for read-only mount)
673 * nilfs_find_sbinfo() returns the nilfs_sb_info structure which
674 * @rw_mount and @cno (in case of snapshots) matched. If no instance
675 * was found, NULL is returned. Although the super block instance can
676 * be unmounted after this function returns, the nilfs_sb_info struct
677 * is kept on memory until nilfs_put_sbinfo() is called.
679 struct nilfs_sb_info
*nilfs_find_sbinfo(struct the_nilfs
*nilfs
,
680 int rw_mount
, __u64 cno
)
682 struct nilfs_sb_info
*sbi
;
684 down_read(&nilfs
->ns_sem
);
686 * The SNAPSHOT flag and sb->s_flags are supposed to be
687 * protected with nilfs->ns_sem.
689 sbi
= nilfs
->ns_current
;
691 if (sbi
&& !(sbi
->s_super
->s_flags
& MS_RDONLY
))
692 goto found
; /* read/write mount */
695 } else if (cno
== 0) {
696 if (sbi
&& (sbi
->s_super
->s_flags
& MS_RDONLY
))
697 goto found
; /* read-only mount */
702 list_for_each_entry(sbi
, &nilfs
->ns_supers
, s_list
) {
703 if (nilfs_test_opt(sbi
, SNAPSHOT
) &&
704 sbi
->s_snapshot_cno
== cno
)
705 goto found
; /* snapshot mount */
708 up_read(&nilfs
->ns_sem
);
712 atomic_inc(&sbi
->s_count
);
713 up_read(&nilfs
->ns_sem
);
717 int nilfs_checkpoint_is_mounted(struct the_nilfs
*nilfs
, __u64 cno
,
720 struct nilfs_sb_info
*sbi
;
723 down_read(&nilfs
->ns_sem
);
724 if (cno
== 0 || cno
> nilfs
->ns_cno
)
727 list_for_each_entry(sbi
, &nilfs
->ns_supers
, s_list
) {
728 if (sbi
->s_snapshot_cno
== cno
&&
729 (!snapshot_mount
|| nilfs_test_opt(sbi
, SNAPSHOT
))) {
730 /* exclude read-only mounts */
735 /* for protecting recent checkpoints */
736 if (cno
>= nilfs_last_cno(nilfs
))
740 up_read(&nilfs
->ns_sem
);