2 * cpfile.c - NILFS checkpoint file.
4 * Copyright (C) 2006-2008 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 Koji Sato <koji@osrg.net>.
23 #include <linux/kernel.h>
25 #include <linux/string.h>
26 #include <linux/buffer_head.h>
27 #include <linux/errno.h>
28 #include <linux/nilfs2_fs.h>
33 static inline unsigned long
34 nilfs_cpfile_checkpoints_per_block(const struct inode *cpfile)
36 return NILFS_MDT(cpfile)->mi_entries_per_block;
39 /* block number from the beginning of the file */
41 nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
43 __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
44 do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
45 return (unsigned long)tcno;
50 nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
52 __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
53 return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
57 nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
62 nilfs_cpfile_checkpoints_per_block(cpfile) -
63 nilfs_cpfile_get_offset(cpfile, curr),
67 static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
70 return nilfs_cpfile_get_blkoff(cpfile, cno) == 0;
74 nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
75 struct buffer_head *bh,
79 struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
82 count = le32_to_cpu(cp->cp_checkpoints_count) + n;
83 cp->cp_checkpoints_count = cpu_to_le32(count);
88 nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
89 struct buffer_head *bh,
93 struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
96 WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
97 count = le32_to_cpu(cp->cp_checkpoints_count) - n;
98 cp->cp_checkpoints_count = cpu_to_le32(count);
102 static inline struct nilfs_cpfile_header *
103 nilfs_cpfile_block_get_header(const struct inode *cpfile,
104 struct buffer_head *bh,
107 return kaddr + bh_offset(bh);
110 static struct nilfs_checkpoint *
111 nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
112 struct buffer_head *bh,
115 return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
116 NILFS_MDT(cpfile)->mi_entry_size;
119 static void nilfs_cpfile_block_init(struct inode *cpfile,
120 struct buffer_head *bh,
123 struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
124 size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
125 int n = nilfs_cpfile_checkpoints_per_block(cpfile);
128 nilfs_checkpoint_set_invalid(cp);
129 cp = (void *)cp + cpsz;
133 static inline int nilfs_cpfile_get_header_block(struct inode *cpfile,
134 struct buffer_head **bhp)
136 return nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
139 static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
142 struct buffer_head **bhp)
144 return nilfs_mdt_get_block(cpfile,
145 nilfs_cpfile_get_blkoff(cpfile, cno),
146 create, nilfs_cpfile_block_init, bhp);
149 static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
152 return nilfs_mdt_delete_block(cpfile,
153 nilfs_cpfile_get_blkoff(cpfile, cno));
157 * nilfs_cpfile_get_checkpoint - get a checkpoint
158 * @cpfile: inode of checkpoint file
159 * @cno: checkpoint number
160 * @create: create flag
161 * @cpp: pointer to a checkpoint
162 * @bhp: pointer to a buffer head
164 * Description: nilfs_cpfile_get_checkpoint() acquires the checkpoint
165 * specified by @cno. A new checkpoint will be created if @cno is the current
166 * checkpoint number and @create is nonzero.
168 * Return Value: On success, 0 is returned, and the checkpoint and the
169 * buffer head of the buffer on which the checkpoint is located are stored in
170 * the place pointed by @cpp and @bhp, respectively. On error, one of the
171 * following negative error codes is returned.
175 * %-ENOMEM - Insufficient amount of memory available.
177 * %-ENOENT - No such checkpoint.
179 * %-EINVAL - invalid checkpoint.
181 int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
184 struct nilfs_checkpoint **cpp,
185 struct buffer_head **bhp)
187 struct buffer_head *header_bh, *cp_bh;
188 struct nilfs_cpfile_header *header;
189 struct nilfs_checkpoint *cp;
193 if (unlikely(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
194 (cno < nilfs_mdt_cno(cpfile) && create)))
197 down_write(&NILFS_MDT(cpfile)->mi_sem);
199 ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
202 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, create, &cp_bh);
205 kaddr = kmap(cp_bh->b_page);
206 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
207 if (nilfs_checkpoint_invalid(cp)) {
209 kunmap(cp_bh->b_page);
214 /* a newly-created checkpoint */
215 nilfs_checkpoint_clear_invalid(cp);
216 if (!nilfs_cpfile_is_in_first(cpfile, cno))
217 nilfs_cpfile_block_add_valid_checkpoints(cpfile, cp_bh,
219 mark_buffer_dirty(cp_bh);
221 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
222 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
224 le64_add_cpu(&header->ch_ncheckpoints, 1);
225 kunmap_atomic(kaddr, KM_USER0);
226 mark_buffer_dirty(header_bh);
227 nilfs_mdt_mark_dirty(cpfile);
238 up_write(&NILFS_MDT(cpfile)->mi_sem);
243 * nilfs_cpfile_put_checkpoint - put a checkpoint
244 * @cpfile: inode of checkpoint file
245 * @cno: checkpoint number
248 * Description: nilfs_cpfile_put_checkpoint() releases the checkpoint
249 * specified by @cno. @bh must be the buffer head which has been returned by
250 * a previous call to nilfs_cpfile_get_checkpoint() with @cno.
252 void nilfs_cpfile_put_checkpoint(struct inode *cpfile, __u64 cno,
253 struct buffer_head *bh)
260 * nilfs_cpfile_delete_checkpoints - delete checkpoints
261 * @cpfile: inode of checkpoint file
262 * @start: start checkpoint number
263 * @end: end checkpoint numer
265 * Description: nilfs_cpfile_delete_checkpoints() deletes the checkpoints in
266 * the period from @start to @end, excluding @end itself. The checkpoints
267 * which have been already deleted are ignored.
269 * Return Value: On success, 0 is returned. On error, one of the following
270 * negative error codes is returned.
274 * %-ENOMEM - Insufficient amount of memory available.
276 * %-EINVAL - invalid checkpoints.
278 int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
282 struct buffer_head *header_bh, *cp_bh;
283 struct nilfs_cpfile_header *header;
284 struct nilfs_checkpoint *cp;
285 size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
288 unsigned long tnicps;
289 int ret, ncps, nicps, count, i;
291 if (unlikely(start == 0 || start > end)) {
292 printk(KERN_ERR "%s: invalid range of checkpoint numbers: "
293 "[%llu, %llu)\n", __func__,
294 (unsigned long long)start, (unsigned long long)end);
298 down_write(&NILFS_MDT(cpfile)->mi_sem);
300 ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
305 for (cno = start; cno < end; cno += ncps) {
306 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
307 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
316 kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
317 cp = nilfs_cpfile_block_get_checkpoint(
318 cpfile, cno, cp_bh, kaddr);
320 for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
321 WARN_ON(nilfs_checkpoint_snapshot(cp));
322 if (!nilfs_checkpoint_invalid(cp)) {
323 nilfs_checkpoint_set_invalid(cp);
329 mark_buffer_dirty(cp_bh);
330 nilfs_mdt_mark_dirty(cpfile);
331 if (!nilfs_cpfile_is_in_first(cpfile, cno)) {
333 nilfs_cpfile_block_sub_valid_checkpoints(
334 cpfile, cp_bh, kaddr, nicps);
337 kunmap_atomic(kaddr, KM_USER0);
340 nilfs_cpfile_delete_checkpoint_block(
345 "%s: cannot delete block\n",
352 kunmap_atomic(kaddr, KM_USER0);
357 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
358 header = nilfs_cpfile_block_get_header(cpfile, header_bh,
360 le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
361 mark_buffer_dirty(header_bh);
362 nilfs_mdt_mark_dirty(cpfile);
363 kunmap_atomic(kaddr, KM_USER0);
369 up_write(&NILFS_MDT(cpfile)->mi_sem);
373 static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
374 struct nilfs_checkpoint *cp,
375 struct nilfs_cpinfo *ci)
377 ci->ci_flags = le32_to_cpu(cp->cp_flags);
378 ci->ci_cno = le64_to_cpu(cp->cp_cno);
379 ci->ci_create = le64_to_cpu(cp->cp_create);
380 ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
381 ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
382 ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
383 ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
386 static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
387 void *buf, unsigned cisz, size_t nci)
389 struct nilfs_checkpoint *cp;
390 struct nilfs_cpinfo *ci = buf;
391 struct buffer_head *bh;
392 size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
393 __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
399 return -ENOENT; /* checkpoint number 0 is invalid */
400 down_read(&NILFS_MDT(cpfile)->mi_sem);
402 for (n = 0; cno < cur_cno && n < nci; cno += ncps) {
403 ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
404 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
408 continue; /* skip hole */
411 kaddr = kmap_atomic(bh->b_page, KM_USER0);
412 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
413 for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
414 if (!nilfs_checkpoint_invalid(cp)) {
415 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
417 ci = (void *)ci + cisz;
421 kunmap_atomic(kaddr, KM_USER0);
427 ci = (void *)ci - cisz;
428 *cnop = ci->ci_cno + 1;
432 up_read(&NILFS_MDT(cpfile)->mi_sem);
436 static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
437 void *buf, unsigned cisz, size_t nci)
439 struct buffer_head *bh;
440 struct nilfs_cpfile_header *header;
441 struct nilfs_checkpoint *cp;
442 struct nilfs_cpinfo *ci = buf;
443 __u64 curr = *cnop, next;
444 unsigned long curr_blkoff, next_blkoff;
448 down_read(&NILFS_MDT(cpfile)->mi_sem);
451 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
454 kaddr = kmap_atomic(bh->b_page, KM_USER0);
455 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
456 curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
457 kunmap_atomic(kaddr, KM_USER0);
463 } else if (unlikely(curr == ~(__u64)0)) {
468 curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
469 ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
470 if (unlikely(ret < 0)) {
472 ret = 0; /* No snapshots (started from a hole block) */
475 kaddr = kmap_atomic(bh->b_page, KM_USER0);
477 cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
478 curr = ~(__u64)0; /* Terminator */
479 if (unlikely(nilfs_checkpoint_invalid(cp) ||
480 !nilfs_checkpoint_snapshot(cp)))
482 nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
483 ci = (void *)ci + cisz;
485 next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
487 break; /* reach end of the snapshot list */
489 next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
490 if (curr_blkoff != next_blkoff) {
491 kunmap_atomic(kaddr, KM_USER0);
493 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
495 if (unlikely(ret < 0)) {
496 WARN_ON(ret == -ENOENT);
499 kaddr = kmap_atomic(bh->b_page, KM_USER0);
502 curr_blkoff = next_blkoff;
504 kunmap_atomic(kaddr, KM_USER0);
510 up_read(&NILFS_MDT(cpfile)->mi_sem);
515 * nilfs_cpfile_get_cpinfo -
522 ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
523 void *buf, unsigned cisz, size_t nci)
526 case NILFS_CHECKPOINT:
527 return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
529 return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
536 * nilfs_cpfile_delete_checkpoint -
540 int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
542 struct nilfs_cpinfo ci;
546 nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
549 else if (nci == 0 || ci.ci_cno != cno)
551 else if (nilfs_cpinfo_snapshot(&ci))
554 return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
557 static struct nilfs_snapshot_list *
558 nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
560 struct buffer_head *bh,
563 struct nilfs_cpfile_header *header;
564 struct nilfs_checkpoint *cp;
565 struct nilfs_snapshot_list *list;
568 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
569 list = &cp->cp_snapshot_list;
571 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
572 list = &header->ch_snapshot_list;
577 static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
579 struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
580 struct nilfs_cpfile_header *header;
581 struct nilfs_checkpoint *cp;
582 struct nilfs_snapshot_list *list;
584 unsigned long curr_blkoff, prev_blkoff;
589 return -ENOENT; /* checkpoint number 0 is invalid */
590 down_write(&NILFS_MDT(cpfile)->mi_sem);
592 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
595 kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
596 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
597 if (nilfs_checkpoint_invalid(cp)) {
599 kunmap_atomic(kaddr, KM_USER0);
602 if (nilfs_checkpoint_snapshot(cp)) {
604 kunmap_atomic(kaddr, KM_USER0);
607 kunmap_atomic(kaddr, KM_USER0);
609 ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
612 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
613 header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
614 list = &header->ch_snapshot_list;
619 prev = le64_to_cpu(list->ssl_prev);
621 prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
623 if (curr_blkoff != prev_blkoff) {
624 kunmap_atomic(kaddr, KM_USER0);
626 ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
630 kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
632 curr_blkoff = prev_blkoff;
633 cp = nilfs_cpfile_block_get_checkpoint(
634 cpfile, curr, curr_bh, kaddr);
635 list = &cp->cp_snapshot_list;
636 prev = le64_to_cpu(list->ssl_prev);
638 kunmap_atomic(kaddr, KM_USER0);
641 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
650 kaddr = kmap_atomic(curr_bh->b_page, KM_USER0);
651 list = nilfs_cpfile_block_get_snapshot_list(
652 cpfile, curr, curr_bh, kaddr);
653 list->ssl_prev = cpu_to_le64(cno);
654 kunmap_atomic(kaddr, KM_USER0);
656 kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
657 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
658 cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
659 cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
660 nilfs_checkpoint_set_snapshot(cp);
661 kunmap_atomic(kaddr, KM_USER0);
663 kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
664 list = nilfs_cpfile_block_get_snapshot_list(
665 cpfile, prev, prev_bh, kaddr);
666 list->ssl_next = cpu_to_le64(cno);
667 kunmap_atomic(kaddr, KM_USER0);
669 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
670 header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
671 le64_add_cpu(&header->ch_nsnapshots, 1);
672 kunmap_atomic(kaddr, KM_USER0);
674 mark_buffer_dirty(prev_bh);
675 mark_buffer_dirty(curr_bh);
676 mark_buffer_dirty(cp_bh);
677 mark_buffer_dirty(header_bh);
678 nilfs_mdt_mark_dirty(cpfile);
692 up_write(&NILFS_MDT(cpfile)->mi_sem);
696 static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
698 struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
699 struct nilfs_cpfile_header *header;
700 struct nilfs_checkpoint *cp;
701 struct nilfs_snapshot_list *list;
707 return -ENOENT; /* checkpoint number 0 is invalid */
708 down_write(&NILFS_MDT(cpfile)->mi_sem);
710 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
713 kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
714 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
715 if (nilfs_checkpoint_invalid(cp)) {
717 kunmap_atomic(kaddr, KM_USER0);
720 if (!nilfs_checkpoint_snapshot(cp)) {
722 kunmap_atomic(kaddr, KM_USER0);
726 list = &cp->cp_snapshot_list;
727 next = le64_to_cpu(list->ssl_next);
728 prev = le64_to_cpu(list->ssl_prev);
729 kunmap_atomic(kaddr, KM_USER0);
731 ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
735 ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
744 ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
753 kaddr = kmap_atomic(next_bh->b_page, KM_USER0);
754 list = nilfs_cpfile_block_get_snapshot_list(
755 cpfile, next, next_bh, kaddr);
756 list->ssl_prev = cpu_to_le64(prev);
757 kunmap_atomic(kaddr, KM_USER0);
759 kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
760 list = nilfs_cpfile_block_get_snapshot_list(
761 cpfile, prev, prev_bh, kaddr);
762 list->ssl_next = cpu_to_le64(next);
763 kunmap_atomic(kaddr, KM_USER0);
765 kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
766 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
767 cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
768 cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
769 nilfs_checkpoint_clear_snapshot(cp);
770 kunmap_atomic(kaddr, KM_USER0);
772 kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
773 header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
774 le64_add_cpu(&header->ch_nsnapshots, -1);
775 kunmap_atomic(kaddr, KM_USER0);
777 mark_buffer_dirty(next_bh);
778 mark_buffer_dirty(prev_bh);
779 mark_buffer_dirty(cp_bh);
780 mark_buffer_dirty(header_bh);
781 nilfs_mdt_mark_dirty(cpfile);
795 up_write(&NILFS_MDT(cpfile)->mi_sem);
800 * nilfs_cpfile_is_snapshot -
801 * @cpfile: inode of checkpoint file
802 * @cno: checkpoint number
806 * Return Value: On success, 1 is returned if the checkpoint specified by
807 * @cno is a snapshot, or 0 if not. On error, one of the following negative
808 * error codes is returned.
812 * %-ENOMEM - Insufficient amount of memory available.
814 * %-ENOENT - No such checkpoint.
816 int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
818 struct buffer_head *bh;
819 struct nilfs_checkpoint *cp;
823 /* CP number is invalid if it's zero or larger than the
825 if (cno == 0 || cno >= nilfs_mdt_cno(cpfile))
827 down_read(&NILFS_MDT(cpfile)->mi_sem);
829 ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
832 kaddr = kmap_atomic(bh->b_page, KM_USER0);
833 cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
834 if (nilfs_checkpoint_invalid(cp))
837 ret = nilfs_checkpoint_snapshot(cp);
838 kunmap_atomic(kaddr, KM_USER0);
842 up_read(&NILFS_MDT(cpfile)->mi_sem);
847 * nilfs_cpfile_change_cpmode - change checkpoint mode
848 * @cpfile: inode of checkpoint file
849 * @cno: checkpoint number
850 * @status: mode of checkpoint
852 * Description: nilfs_change_cpmode() changes the mode of the checkpoint
853 * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
855 * Return Value: On success, 0 is returned. On error, one of the following
856 * negative error codes is returned.
860 * %-ENOMEM - Insufficient amount of memory available.
862 * %-ENOENT - No such checkpoint.
864 int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
869 case NILFS_CHECKPOINT:
870 if (nilfs_checkpoint_is_mounted(cpfile->i_sb, cno))
872 * Current implementation does not have to protect
873 * plain read-only mounts since they are exclusive
874 * with a read/write mount and are protected from the
879 ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
882 return nilfs_cpfile_set_snapshot(cpfile, cno);
889 * nilfs_cpfile_get_stat - get checkpoint statistics
890 * @cpfile: inode of checkpoint file
891 * @stat: pointer to a structure of checkpoint statistics
893 * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
895 * Return Value: On success, 0 is returned, and checkpoints information is
896 * stored in the place pointed by @stat. On error, one of the following
897 * negative error codes is returned.
901 * %-ENOMEM - Insufficient amount of memory available.
903 int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
905 struct buffer_head *bh;
906 struct nilfs_cpfile_header *header;
910 down_read(&NILFS_MDT(cpfile)->mi_sem);
912 ret = nilfs_cpfile_get_header_block(cpfile, &bh);
915 kaddr = kmap_atomic(bh->b_page, KM_USER0);
916 header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
917 cpstat->cs_cno = nilfs_mdt_cno(cpfile);
918 cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
919 cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
920 kunmap_atomic(kaddr, KM_USER0);
924 up_read(&NILFS_MDT(cpfile)->mi_sem);
929 * nilfs_cpfile_read - read or get cpfile inode
930 * @sb: super block instance
931 * @cpsize: size of a checkpoint entry
932 * @raw_inode: on-disk cpfile inode
933 * @inodep: buffer to store the inode
935 int nilfs_cpfile_read(struct super_block *sb, size_t cpsize,
936 struct nilfs_inode *raw_inode, struct inode **inodep)
938 struct inode *cpfile;
941 cpfile = nilfs_iget_locked(sb, NULL, NILFS_CPFILE_INO);
942 if (unlikely(!cpfile))
944 if (!(cpfile->i_state & I_NEW))
947 err = nilfs_mdt_init(cpfile, NILFS_MDT_GFP, 0);
951 nilfs_mdt_set_entry_size(cpfile, cpsize,
952 sizeof(struct nilfs_cpfile_header));
954 err = nilfs_read_inode_common(cpfile, raw_inode);
958 unlock_new_inode(cpfile);