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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /fs/nilfs2/cpfile.c
Initial import
Diffstat (limited to 'fs/nilfs2/cpfile.c')
-rw-r--r--fs/nilfs2/cpfile.c1027
1 files changed, 1027 insertions, 0 deletions
diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
new file mode 100644
index 000000000..b6596cab9
--- /dev/null
+++ b/fs/nilfs2/cpfile.c
@@ -0,0 +1,1027 @@
+/*
+ * cpfile.c - NILFS checkpoint file.
+ *
+ * Copyright (C) 2006-2008 Nippon Telegraph and Telephone Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ *
+ * Written by Koji Sato <koji@osrg.net>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/string.h>
+#include <linux/buffer_head.h>
+#include <linux/errno.h>
+#include <linux/nilfs2_fs.h>
+#include "mdt.h"
+#include "cpfile.h"
+
+
+static inline unsigned long
+nilfs_cpfile_checkpoints_per_block(const struct inode *cpfile)
+{
+ return NILFS_MDT(cpfile)->mi_entries_per_block;
+}
+
+/* block number from the beginning of the file */
+static unsigned long
+nilfs_cpfile_get_blkoff(const struct inode *cpfile, __u64 cno)
+{
+ __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
+ do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
+ return (unsigned long)tcno;
+}
+
+/* offset in block */
+static unsigned long
+nilfs_cpfile_get_offset(const struct inode *cpfile, __u64 cno)
+{
+ __u64 tcno = cno + NILFS_MDT(cpfile)->mi_first_entry_offset - 1;
+ return do_div(tcno, nilfs_cpfile_checkpoints_per_block(cpfile));
+}
+
+static __u64 nilfs_cpfile_first_checkpoint_in_block(const struct inode *cpfile,
+ unsigned long blkoff)
+{
+ return (__u64)nilfs_cpfile_checkpoints_per_block(cpfile) * blkoff
+ + 1 - NILFS_MDT(cpfile)->mi_first_entry_offset;
+}
+
+static unsigned long
+nilfs_cpfile_checkpoints_in_block(const struct inode *cpfile,
+ __u64 curr,
+ __u64 max)
+{
+ return min_t(__u64,
+ nilfs_cpfile_checkpoints_per_block(cpfile) -
+ nilfs_cpfile_get_offset(cpfile, curr),
+ max - curr);
+}
+
+static inline int nilfs_cpfile_is_in_first(const struct inode *cpfile,
+ __u64 cno)
+{
+ return nilfs_cpfile_get_blkoff(cpfile, cno) == 0;
+}
+
+static unsigned int
+nilfs_cpfile_block_add_valid_checkpoints(const struct inode *cpfile,
+ struct buffer_head *bh,
+ void *kaddr,
+ unsigned int n)
+{
+ struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+ unsigned int count;
+
+ count = le32_to_cpu(cp->cp_checkpoints_count) + n;
+ cp->cp_checkpoints_count = cpu_to_le32(count);
+ return count;
+}
+
+static unsigned int
+nilfs_cpfile_block_sub_valid_checkpoints(const struct inode *cpfile,
+ struct buffer_head *bh,
+ void *kaddr,
+ unsigned int n)
+{
+ struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+ unsigned int count;
+
+ WARN_ON(le32_to_cpu(cp->cp_checkpoints_count) < n);
+ count = le32_to_cpu(cp->cp_checkpoints_count) - n;
+ cp->cp_checkpoints_count = cpu_to_le32(count);
+ return count;
+}
+
+static inline struct nilfs_cpfile_header *
+nilfs_cpfile_block_get_header(const struct inode *cpfile,
+ struct buffer_head *bh,
+ void *kaddr)
+{
+ return kaddr + bh_offset(bh);
+}
+
+static struct nilfs_checkpoint *
+nilfs_cpfile_block_get_checkpoint(const struct inode *cpfile, __u64 cno,
+ struct buffer_head *bh,
+ void *kaddr)
+{
+ return kaddr + bh_offset(bh) + nilfs_cpfile_get_offset(cpfile, cno) *
+ NILFS_MDT(cpfile)->mi_entry_size;
+}
+
+static void nilfs_cpfile_block_init(struct inode *cpfile,
+ struct buffer_head *bh,
+ void *kaddr)
+{
+ struct nilfs_checkpoint *cp = kaddr + bh_offset(bh);
+ size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
+ int n = nilfs_cpfile_checkpoints_per_block(cpfile);
+
+ while (n-- > 0) {
+ nilfs_checkpoint_set_invalid(cp);
+ cp = (void *)cp + cpsz;
+ }
+}
+
+static inline int nilfs_cpfile_get_header_block(struct inode *cpfile,
+ struct buffer_head **bhp)
+{
+ return nilfs_mdt_get_block(cpfile, 0, 0, NULL, bhp);
+}
+
+static inline int nilfs_cpfile_get_checkpoint_block(struct inode *cpfile,
+ __u64 cno,
+ int create,
+ struct buffer_head **bhp)
+{
+ return nilfs_mdt_get_block(cpfile,
+ nilfs_cpfile_get_blkoff(cpfile, cno),
+ create, nilfs_cpfile_block_init, bhp);
+}
+
+/**
+ * nilfs_cpfile_find_checkpoint_block - find and get a buffer on cpfile
+ * @cpfile: inode of cpfile
+ * @start_cno: start checkpoint number (inclusive)
+ * @end_cno: end checkpoint number (inclusive)
+ * @cnop: place to store the next checkpoint number
+ * @bhp: place to store a pointer to buffer_head struct
+ *
+ * Return Value: On success, it returns 0. On error, the following negative
+ * error code is returned.
+ *
+ * %-ENOMEM - Insufficient memory available.
+ *
+ * %-EIO - I/O error
+ *
+ * %-ENOENT - no block exists in the range.
+ */
+static int nilfs_cpfile_find_checkpoint_block(struct inode *cpfile,
+ __u64 start_cno, __u64 end_cno,
+ __u64 *cnop,
+ struct buffer_head **bhp)
+{
+ unsigned long start, end, blkoff;
+ int ret;
+
+ if (unlikely(start_cno > end_cno))
+ return -ENOENT;
+
+ start = nilfs_cpfile_get_blkoff(cpfile, start_cno);
+ end = nilfs_cpfile_get_blkoff(cpfile, end_cno);
+
+ ret = nilfs_mdt_find_block(cpfile, start, end, &blkoff, bhp);
+ if (!ret)
+ *cnop = (blkoff == start) ? start_cno :
+ nilfs_cpfile_first_checkpoint_in_block(cpfile, blkoff);
+ return ret;
+}
+
+static inline int nilfs_cpfile_delete_checkpoint_block(struct inode *cpfile,
+ __u64 cno)
+{
+ return nilfs_mdt_delete_block(cpfile,
+ nilfs_cpfile_get_blkoff(cpfile, cno));
+}
+
+/**
+ * nilfs_cpfile_get_checkpoint - get a checkpoint
+ * @cpfile: inode of checkpoint file
+ * @cno: checkpoint number
+ * @create: create flag
+ * @cpp: pointer to a checkpoint
+ * @bhp: pointer to a buffer head
+ *
+ * Description: nilfs_cpfile_get_checkpoint() acquires the checkpoint
+ * specified by @cno. A new checkpoint will be created if @cno is the current
+ * checkpoint number and @create is nonzero.
+ *
+ * Return Value: On success, 0 is returned, and the checkpoint and the
+ * buffer head of the buffer on which the checkpoint is located are stored in
+ * the place pointed by @cpp and @bhp, respectively. On error, one of the
+ * following negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - No such checkpoint.
+ *
+ * %-EINVAL - invalid checkpoint.
+ */
+int nilfs_cpfile_get_checkpoint(struct inode *cpfile,
+ __u64 cno,
+ int create,
+ struct nilfs_checkpoint **cpp,
+ struct buffer_head **bhp)
+{
+ struct buffer_head *header_bh, *cp_bh;
+ struct nilfs_cpfile_header *header;
+ struct nilfs_checkpoint *cp;
+ void *kaddr;
+ int ret;
+
+ if (unlikely(cno < 1 || cno > nilfs_mdt_cno(cpfile) ||
+ (cno < nilfs_mdt_cno(cpfile) && create)))
+ return -EINVAL;
+
+ down_write(&NILFS_MDT(cpfile)->mi_sem);
+
+ ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+ if (ret < 0)
+ goto out_sem;
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, create, &cp_bh);
+ if (ret < 0)
+ goto out_header;
+ kaddr = kmap(cp_bh->b_page);
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+ if (nilfs_checkpoint_invalid(cp)) {
+ if (!create) {
+ kunmap(cp_bh->b_page);
+ brelse(cp_bh);
+ ret = -ENOENT;
+ goto out_header;
+ }
+ /* a newly-created checkpoint */
+ nilfs_checkpoint_clear_invalid(cp);
+ if (!nilfs_cpfile_is_in_first(cpfile, cno))
+ nilfs_cpfile_block_add_valid_checkpoints(cpfile, cp_bh,
+ kaddr, 1);
+ mark_buffer_dirty(cp_bh);
+
+ kaddr = kmap_atomic(header_bh->b_page);
+ header = nilfs_cpfile_block_get_header(cpfile, header_bh,
+ kaddr);
+ le64_add_cpu(&header->ch_ncheckpoints, 1);
+ kunmap_atomic(kaddr);
+ mark_buffer_dirty(header_bh);
+ nilfs_mdt_mark_dirty(cpfile);
+ }
+
+ if (cpp != NULL)
+ *cpp = cp;
+ *bhp = cp_bh;
+
+ out_header:
+ brelse(header_bh);
+
+ out_sem:
+ up_write(&NILFS_MDT(cpfile)->mi_sem);
+ return ret;
+}
+
+/**
+ * nilfs_cpfile_put_checkpoint - put a checkpoint
+ * @cpfile: inode of checkpoint file
+ * @cno: checkpoint number
+ * @bh: buffer head
+ *
+ * Description: nilfs_cpfile_put_checkpoint() releases the checkpoint
+ * specified by @cno. @bh must be the buffer head which has been returned by
+ * a previous call to nilfs_cpfile_get_checkpoint() with @cno.
+ */
+void nilfs_cpfile_put_checkpoint(struct inode *cpfile, __u64 cno,
+ struct buffer_head *bh)
+{
+ kunmap(bh->b_page);
+ brelse(bh);
+}
+
+/**
+ * nilfs_cpfile_delete_checkpoints - delete checkpoints
+ * @cpfile: inode of checkpoint file
+ * @start: start checkpoint number
+ * @end: end checkpoint numer
+ *
+ * Description: nilfs_cpfile_delete_checkpoints() deletes the checkpoints in
+ * the period from @start to @end, excluding @end itself. The checkpoints
+ * which have been already deleted are ignored.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-EINVAL - invalid checkpoints.
+ */
+int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
+ __u64 start,
+ __u64 end)
+{
+ struct buffer_head *header_bh, *cp_bh;
+ struct nilfs_cpfile_header *header;
+ struct nilfs_checkpoint *cp;
+ size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
+ __u64 cno;
+ void *kaddr;
+ unsigned long tnicps;
+ int ret, ncps, nicps, nss, count, i;
+
+ if (unlikely(start == 0 || start > end)) {
+ printk(KERN_ERR "%s: invalid range of checkpoint numbers: "
+ "[%llu, %llu)\n", __func__,
+ (unsigned long long)start, (unsigned long long)end);
+ return -EINVAL;
+ }
+
+ down_write(&NILFS_MDT(cpfile)->mi_sem);
+
+ ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+ if (ret < 0)
+ goto out_sem;
+ tnicps = 0;
+ nss = 0;
+
+ for (cno = start; cno < end; cno += ncps) {
+ ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
+ if (ret < 0) {
+ if (ret != -ENOENT)
+ break;
+ /* skip hole */
+ ret = 0;
+ continue;
+ }
+
+ kaddr = kmap_atomic(cp_bh->b_page);
+ cp = nilfs_cpfile_block_get_checkpoint(
+ cpfile, cno, cp_bh, kaddr);
+ nicps = 0;
+ for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
+ if (nilfs_checkpoint_snapshot(cp)) {
+ nss++;
+ } else if (!nilfs_checkpoint_invalid(cp)) {
+ nilfs_checkpoint_set_invalid(cp);
+ nicps++;
+ }
+ }
+ if (nicps > 0) {
+ tnicps += nicps;
+ mark_buffer_dirty(cp_bh);
+ nilfs_mdt_mark_dirty(cpfile);
+ if (!nilfs_cpfile_is_in_first(cpfile, cno)) {
+ count =
+ nilfs_cpfile_block_sub_valid_checkpoints(
+ cpfile, cp_bh, kaddr, nicps);
+ if (count == 0) {
+ /* make hole */
+ kunmap_atomic(kaddr);
+ brelse(cp_bh);
+ ret =
+ nilfs_cpfile_delete_checkpoint_block(
+ cpfile, cno);
+ if (ret == 0)
+ continue;
+ printk(KERN_ERR
+ "%s: cannot delete block\n",
+ __func__);
+ break;
+ }
+ }
+ }
+
+ kunmap_atomic(kaddr);
+ brelse(cp_bh);
+ }
+
+ if (tnicps > 0) {
+ kaddr = kmap_atomic(header_bh->b_page);
+ header = nilfs_cpfile_block_get_header(cpfile, header_bh,
+ kaddr);
+ le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
+ mark_buffer_dirty(header_bh);
+ nilfs_mdt_mark_dirty(cpfile);
+ kunmap_atomic(kaddr);
+ }
+
+ brelse(header_bh);
+ if (nss > 0)
+ ret = -EBUSY;
+
+ out_sem:
+ up_write(&NILFS_MDT(cpfile)->mi_sem);
+ return ret;
+}
+
+static void nilfs_cpfile_checkpoint_to_cpinfo(struct inode *cpfile,
+ struct nilfs_checkpoint *cp,
+ struct nilfs_cpinfo *ci)
+{
+ ci->ci_flags = le32_to_cpu(cp->cp_flags);
+ ci->ci_cno = le64_to_cpu(cp->cp_cno);
+ ci->ci_create = le64_to_cpu(cp->cp_create);
+ ci->ci_nblk_inc = le64_to_cpu(cp->cp_nblk_inc);
+ ci->ci_inodes_count = le64_to_cpu(cp->cp_inodes_count);
+ ci->ci_blocks_count = le64_to_cpu(cp->cp_blocks_count);
+ ci->ci_next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
+}
+
+static ssize_t nilfs_cpfile_do_get_cpinfo(struct inode *cpfile, __u64 *cnop,
+ void *buf, unsigned cisz, size_t nci)
+{
+ struct nilfs_checkpoint *cp;
+ struct nilfs_cpinfo *ci = buf;
+ struct buffer_head *bh;
+ size_t cpsz = NILFS_MDT(cpfile)->mi_entry_size;
+ __u64 cur_cno = nilfs_mdt_cno(cpfile), cno = *cnop;
+ void *kaddr;
+ int n, ret;
+ int ncps, i;
+
+ if (cno == 0)
+ return -ENOENT; /* checkpoint number 0 is invalid */
+ down_read(&NILFS_MDT(cpfile)->mi_sem);
+
+ for (n = 0; n < nci; cno += ncps) {
+ ret = nilfs_cpfile_find_checkpoint_block(
+ cpfile, cno, cur_cno - 1, &cno, &bh);
+ if (ret < 0) {
+ if (likely(ret == -ENOENT))
+ break;
+ goto out;
+ }
+ ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
+
+ kaddr = kmap_atomic(bh->b_page);
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
+ for (i = 0; i < ncps && n < nci; i++, cp = (void *)cp + cpsz) {
+ if (!nilfs_checkpoint_invalid(cp)) {
+ nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp,
+ ci);
+ ci = (void *)ci + cisz;
+ n++;
+ }
+ }
+ kunmap_atomic(kaddr);
+ brelse(bh);
+ }
+
+ ret = n;
+ if (n > 0) {
+ ci = (void *)ci - cisz;
+ *cnop = ci->ci_cno + 1;
+ }
+
+ out:
+ up_read(&NILFS_MDT(cpfile)->mi_sem);
+ return ret;
+}
+
+static ssize_t nilfs_cpfile_do_get_ssinfo(struct inode *cpfile, __u64 *cnop,
+ void *buf, unsigned cisz, size_t nci)
+{
+ struct buffer_head *bh;
+ struct nilfs_cpfile_header *header;
+ struct nilfs_checkpoint *cp;
+ struct nilfs_cpinfo *ci = buf;
+ __u64 curr = *cnop, next;
+ unsigned long curr_blkoff, next_blkoff;
+ void *kaddr;
+ int n = 0, ret;
+
+ down_read(&NILFS_MDT(cpfile)->mi_sem);
+
+ if (curr == 0) {
+ ret = nilfs_cpfile_get_header_block(cpfile, &bh);
+ if (ret < 0)
+ goto out;
+ kaddr = kmap_atomic(bh->b_page);
+ header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
+ curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
+ kunmap_atomic(kaddr);
+ brelse(bh);
+ if (curr == 0) {
+ ret = 0;
+ goto out;
+ }
+ } else if (unlikely(curr == ~(__u64)0)) {
+ ret = 0;
+ goto out;
+ }
+
+ curr_blkoff = nilfs_cpfile_get_blkoff(cpfile, curr);
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr, 0, &bh);
+ if (unlikely(ret < 0)) {
+ if (ret == -ENOENT)
+ ret = 0; /* No snapshots (started from a hole block) */
+ goto out;
+ }
+ kaddr = kmap_atomic(bh->b_page);
+ while (n < nci) {
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, curr, bh, kaddr);
+ curr = ~(__u64)0; /* Terminator */
+ if (unlikely(nilfs_checkpoint_invalid(cp) ||
+ !nilfs_checkpoint_snapshot(cp)))
+ break;
+ nilfs_cpfile_checkpoint_to_cpinfo(cpfile, cp, ci);
+ ci = (void *)ci + cisz;
+ n++;
+ next = le64_to_cpu(cp->cp_snapshot_list.ssl_next);
+ if (next == 0)
+ break; /* reach end of the snapshot list */
+
+ next_blkoff = nilfs_cpfile_get_blkoff(cpfile, next);
+ if (curr_blkoff != next_blkoff) {
+ kunmap_atomic(kaddr);
+ brelse(bh);
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, next,
+ 0, &bh);
+ if (unlikely(ret < 0)) {
+ WARN_ON(ret == -ENOENT);
+ goto out;
+ }
+ kaddr = kmap_atomic(bh->b_page);
+ }
+ curr = next;
+ curr_blkoff = next_blkoff;
+ }
+ kunmap_atomic(kaddr);
+ brelse(bh);
+ *cnop = curr;
+ ret = n;
+
+ out:
+ up_read(&NILFS_MDT(cpfile)->mi_sem);
+ return ret;
+}
+
+/**
+ * nilfs_cpfile_get_cpinfo -
+ * @cpfile:
+ * @cno:
+ * @ci:
+ * @nci:
+ */
+
+ssize_t nilfs_cpfile_get_cpinfo(struct inode *cpfile, __u64 *cnop, int mode,
+ void *buf, unsigned cisz, size_t nci)
+{
+ switch (mode) {
+ case NILFS_CHECKPOINT:
+ return nilfs_cpfile_do_get_cpinfo(cpfile, cnop, buf, cisz, nci);
+ case NILFS_SNAPSHOT:
+ return nilfs_cpfile_do_get_ssinfo(cpfile, cnop, buf, cisz, nci);
+ default:
+ return -EINVAL;
+ }
+}
+
+/**
+ * nilfs_cpfile_delete_checkpoint -
+ * @cpfile:
+ * @cno:
+ */
+int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
+{
+ struct nilfs_cpinfo ci;
+ __u64 tcno = cno;
+ ssize_t nci;
+
+ nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
+ if (nci < 0)
+ return nci;
+ else if (nci == 0 || ci.ci_cno != cno)
+ return -ENOENT;
+ else if (nilfs_cpinfo_snapshot(&ci))
+ return -EBUSY;
+
+ return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
+}
+
+static struct nilfs_snapshot_list *
+nilfs_cpfile_block_get_snapshot_list(const struct inode *cpfile,
+ __u64 cno,
+ struct buffer_head *bh,
+ void *kaddr)
+{
+ struct nilfs_cpfile_header *header;
+ struct nilfs_checkpoint *cp;
+ struct nilfs_snapshot_list *list;
+
+ if (cno != 0) {
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
+ list = &cp->cp_snapshot_list;
+ } else {
+ header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
+ list = &header->ch_snapshot_list;
+ }
+ return list;
+}
+
+static int nilfs_cpfile_set_snapshot(struct inode *cpfile, __u64 cno)
+{
+ struct buffer_head *header_bh, *curr_bh, *prev_bh, *cp_bh;
+ struct nilfs_cpfile_header *header;
+ struct nilfs_checkpoint *cp;
+ struct nilfs_snapshot_list *list;
+ __u64 curr, prev;
+ unsigned long curr_blkoff, prev_blkoff;
+ void *kaddr;
+ int ret;
+
+ if (cno == 0)
+ return -ENOENT; /* checkpoint number 0 is invalid */
+ down_write(&NILFS_MDT(cpfile)->mi_sem);
+
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
+ if (ret < 0)
+ goto out_sem;
+ kaddr = kmap_atomic(cp_bh->b_page);
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+ if (nilfs_checkpoint_invalid(cp)) {
+ ret = -ENOENT;
+ kunmap_atomic(kaddr);
+ goto out_cp;
+ }
+ if (nilfs_checkpoint_snapshot(cp)) {
+ ret = 0;
+ kunmap_atomic(kaddr);
+ goto out_cp;
+ }
+ kunmap_atomic(kaddr);
+
+ ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+ if (ret < 0)
+ goto out_cp;
+ kaddr = kmap_atomic(header_bh->b_page);
+ header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
+ list = &header->ch_snapshot_list;
+ curr_bh = header_bh;
+ get_bh(curr_bh);
+ curr = 0;
+ curr_blkoff = 0;
+ prev = le64_to_cpu(list->ssl_prev);
+ while (prev > cno) {
+ prev_blkoff = nilfs_cpfile_get_blkoff(cpfile, prev);
+ curr = prev;
+ if (curr_blkoff != prev_blkoff) {
+ kunmap_atomic(kaddr);
+ brelse(curr_bh);
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, curr,
+ 0, &curr_bh);
+ if (ret < 0)
+ goto out_header;
+ kaddr = kmap_atomic(curr_bh->b_page);
+ }
+ curr_blkoff = prev_blkoff;
+ cp = nilfs_cpfile_block_get_checkpoint(
+ cpfile, curr, curr_bh, kaddr);
+ list = &cp->cp_snapshot_list;
+ prev = le64_to_cpu(list->ssl_prev);
+ }
+ kunmap_atomic(kaddr);
+
+ if (prev != 0) {
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
+ &prev_bh);
+ if (ret < 0)
+ goto out_curr;
+ } else {
+ prev_bh = header_bh;
+ get_bh(prev_bh);
+ }
+
+ kaddr = kmap_atomic(curr_bh->b_page);
+ list = nilfs_cpfile_block_get_snapshot_list(
+ cpfile, curr, curr_bh, kaddr);
+ list->ssl_prev = cpu_to_le64(cno);
+ kunmap_atomic(kaddr);
+
+ kaddr = kmap_atomic(cp_bh->b_page);
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+ cp->cp_snapshot_list.ssl_next = cpu_to_le64(curr);
+ cp->cp_snapshot_list.ssl_prev = cpu_to_le64(prev);
+ nilfs_checkpoint_set_snapshot(cp);
+ kunmap_atomic(kaddr);
+
+ kaddr = kmap_atomic(prev_bh->b_page);
+ list = nilfs_cpfile_block_get_snapshot_list(
+ cpfile, prev, prev_bh, kaddr);
+ list->ssl_next = cpu_to_le64(cno);
+ kunmap_atomic(kaddr);
+
+ kaddr = kmap_atomic(header_bh->b_page);
+ header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
+ le64_add_cpu(&header->ch_nsnapshots, 1);
+ kunmap_atomic(kaddr);
+
+ mark_buffer_dirty(prev_bh);
+ mark_buffer_dirty(curr_bh);
+ mark_buffer_dirty(cp_bh);
+ mark_buffer_dirty(header_bh);
+ nilfs_mdt_mark_dirty(cpfile);
+
+ brelse(prev_bh);
+
+ out_curr:
+ brelse(curr_bh);
+
+ out_header:
+ brelse(header_bh);
+
+ out_cp:
+ brelse(cp_bh);
+
+ out_sem:
+ up_write(&NILFS_MDT(cpfile)->mi_sem);
+ return ret;
+}
+
+static int nilfs_cpfile_clear_snapshot(struct inode *cpfile, __u64 cno)
+{
+ struct buffer_head *header_bh, *next_bh, *prev_bh, *cp_bh;
+ struct nilfs_cpfile_header *header;
+ struct nilfs_checkpoint *cp;
+ struct nilfs_snapshot_list *list;
+ __u64 next, prev;
+ void *kaddr;
+ int ret;
+
+ if (cno == 0)
+ return -ENOENT; /* checkpoint number 0 is invalid */
+ down_write(&NILFS_MDT(cpfile)->mi_sem);
+
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &cp_bh);
+ if (ret < 0)
+ goto out_sem;
+ kaddr = kmap_atomic(cp_bh->b_page);
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+ if (nilfs_checkpoint_invalid(cp)) {
+ ret = -ENOENT;
+ kunmap_atomic(kaddr);
+ goto out_cp;
+ }
+ if (!nilfs_checkpoint_snapshot(cp)) {
+ ret = 0;
+ kunmap_atomic(kaddr);
+ goto out_cp;
+ }
+
+ list = &cp->cp_snapshot_list;
+ next = le64_to_cpu(list->ssl_next);
+ prev = le64_to_cpu(list->ssl_prev);
+ kunmap_atomic(kaddr);
+
+ ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
+ if (ret < 0)
+ goto out_cp;
+ if (next != 0) {
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, next, 0,
+ &next_bh);
+ if (ret < 0)
+ goto out_header;
+ } else {
+ next_bh = header_bh;
+ get_bh(next_bh);
+ }
+ if (prev != 0) {
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, prev, 0,
+ &prev_bh);
+ if (ret < 0)
+ goto out_next;
+ } else {
+ prev_bh = header_bh;
+ get_bh(prev_bh);
+ }
+
+ kaddr = kmap_atomic(next_bh->b_page);
+ list = nilfs_cpfile_block_get_snapshot_list(
+ cpfile, next, next_bh, kaddr);
+ list->ssl_prev = cpu_to_le64(prev);
+ kunmap_atomic(kaddr);
+
+ kaddr = kmap_atomic(prev_bh->b_page);
+ list = nilfs_cpfile_block_get_snapshot_list(
+ cpfile, prev, prev_bh, kaddr);
+ list->ssl_next = cpu_to_le64(next);
+ kunmap_atomic(kaddr);
+
+ kaddr = kmap_atomic(cp_bh->b_page);
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
+ cp->cp_snapshot_list.ssl_next = cpu_to_le64(0);
+ cp->cp_snapshot_list.ssl_prev = cpu_to_le64(0);
+ nilfs_checkpoint_clear_snapshot(cp);
+ kunmap_atomic(kaddr);
+
+ kaddr = kmap_atomic(header_bh->b_page);
+ header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
+ le64_add_cpu(&header->ch_nsnapshots, -1);
+ kunmap_atomic(kaddr);
+
+ mark_buffer_dirty(next_bh);
+ mark_buffer_dirty(prev_bh);
+ mark_buffer_dirty(cp_bh);
+ mark_buffer_dirty(header_bh);
+ nilfs_mdt_mark_dirty(cpfile);
+
+ brelse(prev_bh);
+
+ out_next:
+ brelse(next_bh);
+
+ out_header:
+ brelse(header_bh);
+
+ out_cp:
+ brelse(cp_bh);
+
+ out_sem:
+ up_write(&NILFS_MDT(cpfile)->mi_sem);
+ return ret;
+}
+
+/**
+ * nilfs_cpfile_is_snapshot -
+ * @cpfile: inode of checkpoint file
+ * @cno: checkpoint number
+ *
+ * Description:
+ *
+ * Return Value: On success, 1 is returned if the checkpoint specified by
+ * @cno is a snapshot, or 0 if not. On error, one of the following negative
+ * error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - No such checkpoint.
+ */
+int nilfs_cpfile_is_snapshot(struct inode *cpfile, __u64 cno)
+{
+ struct buffer_head *bh;
+ struct nilfs_checkpoint *cp;
+ void *kaddr;
+ int ret;
+
+ /* CP number is invalid if it's zero or larger than the
+ largest exist one.*/
+ if (cno == 0 || cno >= nilfs_mdt_cno(cpfile))
+ return -ENOENT;
+ down_read(&NILFS_MDT(cpfile)->mi_sem);
+
+ ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
+ if (ret < 0)
+ goto out;
+ kaddr = kmap_atomic(bh->b_page);
+ cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
+ if (nilfs_checkpoint_invalid(cp))
+ ret = -ENOENT;
+ else
+ ret = nilfs_checkpoint_snapshot(cp);
+ kunmap_atomic(kaddr);
+ brelse(bh);
+
+ out:
+ up_read(&NILFS_MDT(cpfile)->mi_sem);
+ return ret;
+}
+
+/**
+ * nilfs_cpfile_change_cpmode - change checkpoint mode
+ * @cpfile: inode of checkpoint file
+ * @cno: checkpoint number
+ * @status: mode of checkpoint
+ *
+ * Description: nilfs_change_cpmode() changes the mode of the checkpoint
+ * specified by @cno. The mode @mode is NILFS_CHECKPOINT or NILFS_SNAPSHOT.
+ *
+ * Return Value: On success, 0 is returned. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ *
+ * %-ENOENT - No such checkpoint.
+ */
+int nilfs_cpfile_change_cpmode(struct inode *cpfile, __u64 cno, int mode)
+{
+ int ret;
+
+ switch (mode) {
+ case NILFS_CHECKPOINT:
+ if (nilfs_checkpoint_is_mounted(cpfile->i_sb, cno))
+ /*
+ * Current implementation does not have to protect
+ * plain read-only mounts since they are exclusive
+ * with a read/write mount and are protected from the
+ * cleaner.
+ */
+ ret = -EBUSY;
+ else
+ ret = nilfs_cpfile_clear_snapshot(cpfile, cno);
+ return ret;
+ case NILFS_SNAPSHOT:
+ return nilfs_cpfile_set_snapshot(cpfile, cno);
+ default:
+ return -EINVAL;
+ }
+}
+
+/**
+ * nilfs_cpfile_get_stat - get checkpoint statistics
+ * @cpfile: inode of checkpoint file
+ * @stat: pointer to a structure of checkpoint statistics
+ *
+ * Description: nilfs_cpfile_get_stat() returns information about checkpoints.
+ *
+ * Return Value: On success, 0 is returned, and checkpoints information is
+ * stored in the place pointed by @stat. On error, one of the following
+ * negative error codes is returned.
+ *
+ * %-EIO - I/O error.
+ *
+ * %-ENOMEM - Insufficient amount of memory available.
+ */
+int nilfs_cpfile_get_stat(struct inode *cpfile, struct nilfs_cpstat *cpstat)
+{
+ struct buffer_head *bh;
+ struct nilfs_cpfile_header *header;
+ void *kaddr;
+ int ret;
+
+ down_read(&NILFS_MDT(cpfile)->mi_sem);
+
+ ret = nilfs_cpfile_get_header_block(cpfile, &bh);
+ if (ret < 0)
+ goto out_sem;
+ kaddr = kmap_atomic(bh->b_page);
+ header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
+ cpstat->cs_cno = nilfs_mdt_cno(cpfile);
+ cpstat->cs_ncps = le64_to_cpu(header->ch_ncheckpoints);
+ cpstat->cs_nsss = le64_to_cpu(header->ch_nsnapshots);
+ kunmap_atomic(kaddr);
+ brelse(bh);
+
+ out_sem:
+ up_read(&NILFS_MDT(cpfile)->mi_sem);
+ return ret;
+}
+
+/**
+ * nilfs_cpfile_read - read or get cpfile inode
+ * @sb: super block instance
+ * @cpsize: size of a checkpoint entry
+ * @raw_inode: on-disk cpfile inode
+ * @inodep: buffer to store the inode
+ */
+int nilfs_cpfile_read(struct super_block *sb, size_t cpsize,
+ struct nilfs_inode *raw_inode, struct inode **inodep)
+{
+ struct inode *cpfile;
+ int err;
+
+ if (cpsize > sb->s_blocksize) {
+ printk(KERN_ERR
+ "NILFS: too large checkpoint size: %zu bytes.\n",
+ cpsize);
+ return -EINVAL;
+ } else if (cpsize < NILFS_MIN_CHECKPOINT_SIZE) {
+ printk(KERN_ERR
+ "NILFS: too small checkpoint size: %zu bytes.\n",
+ cpsize);
+ return -EINVAL;
+ }
+
+ cpfile = nilfs_iget_locked(sb, NULL, NILFS_CPFILE_INO);
+ if (unlikely(!cpfile))
+ return -ENOMEM;
+ if (!(cpfile->i_state & I_NEW))
+ goto out;
+
+ err = nilfs_mdt_init(cpfile, NILFS_MDT_GFP, 0);
+ if (err)
+ goto failed;
+
+ nilfs_mdt_set_entry_size(cpfile, cpsize,
+ sizeof(struct nilfs_cpfile_header));
+
+ err = nilfs_read_inode_common(cpfile, raw_inode);
+ if (err)
+ goto failed;
+
+ unlock_new_inode(cpfile);
+ out:
+ *inodep = cpfile;
+ return 0;
+ failed:
+ iget_failed(cpfile);
+ return err;
+}