linux/fs/nilfs2/cpfile.c
Jiro SEKIBA d9a0a345ab nilfs2: fix disorder in cp count on error during deleting checkpoints
This fixes a bug that checkpoint count gets wrong on errors when
deleting a series of checkpoints.

The count error is persistent since the checkpoint count is stored on
disk.  Some userland programs refer to the count via ioctl, and this
bugfix is needed to prevent malfunction of such programs.

Signed-off-by: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: stable@kernel.org
2009-07-05 10:44:20 +09:00

926 lines
24 KiB
C

/*
* 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 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);
}
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);
nilfs_mdt_mark_buffer_dirty(cp_bh);
kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
header = nilfs_cpfile_block_get_header(cpfile, header_bh,
kaddr);
le64_add_cpu(&header->ch_ncheckpoints, 1);
kunmap_atomic(kaddr, KM_USER0);
nilfs_mdt_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, 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;
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, KM_USER0);
cp = nilfs_cpfile_block_get_checkpoint(
cpfile, cno, cp_bh, kaddr);
nicps = 0;
for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
WARN_ON(nilfs_checkpoint_snapshot(cp));
if (!nilfs_checkpoint_invalid(cp)) {
nilfs_checkpoint_set_invalid(cp);
nicps++;
}
}
if (nicps > 0) {
tnicps += nicps;
nilfs_mdt_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)) == 0) {
/* make hole */
kunmap_atomic(kaddr, KM_USER0);
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, KM_USER0);
brelse(cp_bh);
}
if (tnicps > 0) {
kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
header = nilfs_cpfile_block_get_header(cpfile, header_bh,
kaddr);
le64_add_cpu(&header->ch_ncheckpoints, -(u64)tnicps);
nilfs_mdt_mark_buffer_dirty(header_bh);
nilfs_mdt_mark_dirty(cpfile);
kunmap_atomic(kaddr, KM_USER0);
}
brelse(header_bh);
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; cno < cur_cno && n < nci; cno += ncps) {
ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, cur_cno);
ret = nilfs_cpfile_get_checkpoint_block(cpfile, cno, 0, &bh);
if (ret < 0) {
if (ret != -ENOENT)
goto out;
continue; /* skip hole */
}
kaddr = kmap_atomic(bh->b_page, KM_USER0);
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, KM_USER0);
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, KM_USER0);
header = nilfs_cpfile_block_get_header(cpfile, bh, kaddr);
curr = le64_to_cpu(header->ch_snapshot_list.ssl_next);
kunmap_atomic(kaddr, KM_USER0);
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, KM_USER0);
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, KM_USER0);
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, KM_USER0);
}
curr = next;
curr_blkoff = next_blkoff;
}
kunmap_atomic(kaddr, KM_USER0);
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, KM_USER0);
cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
if (nilfs_checkpoint_invalid(cp)) {
ret = -ENOENT;
kunmap_atomic(kaddr, KM_USER0);
goto out_cp;
}
if (nilfs_checkpoint_snapshot(cp)) {
ret = 0;
kunmap_atomic(kaddr, KM_USER0);
goto out_cp;
}
kunmap_atomic(kaddr, KM_USER0);
ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
if (ret < 0)
goto out_cp;
kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
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, KM_USER0);
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, KM_USER0);
}
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, KM_USER0);
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, KM_USER0);
list = nilfs_cpfile_block_get_snapshot_list(
cpfile, curr, curr_bh, kaddr);
list->ssl_prev = cpu_to_le64(cno);
kunmap_atomic(kaddr, KM_USER0);
kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
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, KM_USER0);
kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
list = nilfs_cpfile_block_get_snapshot_list(
cpfile, prev, prev_bh, kaddr);
list->ssl_next = cpu_to_le64(cno);
kunmap_atomic(kaddr, KM_USER0);
kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
le64_add_cpu(&header->ch_nsnapshots, 1);
kunmap_atomic(kaddr, KM_USER0);
nilfs_mdt_mark_buffer_dirty(prev_bh);
nilfs_mdt_mark_buffer_dirty(curr_bh);
nilfs_mdt_mark_buffer_dirty(cp_bh);
nilfs_mdt_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, KM_USER0);
cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, cp_bh, kaddr);
if (nilfs_checkpoint_invalid(cp)) {
ret = -ENOENT;
kunmap_atomic(kaddr, KM_USER0);
goto out_cp;
}
if (!nilfs_checkpoint_snapshot(cp)) {
ret = 0;
kunmap_atomic(kaddr, KM_USER0);
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, KM_USER0);
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, KM_USER0);
list = nilfs_cpfile_block_get_snapshot_list(
cpfile, next, next_bh, kaddr);
list->ssl_prev = cpu_to_le64(prev);
kunmap_atomic(kaddr, KM_USER0);
kaddr = kmap_atomic(prev_bh->b_page, KM_USER0);
list = nilfs_cpfile_block_get_snapshot_list(
cpfile, prev, prev_bh, kaddr);
list->ssl_next = cpu_to_le64(next);
kunmap_atomic(kaddr, KM_USER0);
kaddr = kmap_atomic(cp_bh->b_page, KM_USER0);
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, KM_USER0);
kaddr = kmap_atomic(header_bh->b_page, KM_USER0);
header = nilfs_cpfile_block_get_header(cpfile, header_bh, kaddr);
le64_add_cpu(&header->ch_nsnapshots, -1);
kunmap_atomic(kaddr, KM_USER0);
nilfs_mdt_mark_buffer_dirty(next_bh);
nilfs_mdt_mark_buffer_dirty(prev_bh);
nilfs_mdt_mark_buffer_dirty(cp_bh);
nilfs_mdt_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;
if (cno == 0)
return -ENOENT; /* checkpoint number 0 is invalid */
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, KM_USER0);
cp = nilfs_cpfile_block_get_checkpoint(cpfile, cno, bh, kaddr);
ret = nilfs_checkpoint_snapshot(cp);
kunmap_atomic(kaddr, KM_USER0);
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)
{
struct the_nilfs *nilfs;
int ret;
nilfs = NILFS_MDT(cpfile)->mi_nilfs;
switch (mode) {
case NILFS_CHECKPOINT:
/*
* Check for protecting existing snapshot mounts:
* ns_mount_mutex is used to make this operation atomic and
* exclusive with a new mount job. Though it doesn't cover
* umount, it's enough for the purpose.
*/
mutex_lock(&nilfs->ns_mount_mutex);
if (nilfs_checkpoint_is_mounted(nilfs, cno, 1)) {
/* 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);
mutex_unlock(&nilfs->ns_mount_mutex);
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, KM_USER0);
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, KM_USER0);
brelse(bh);
out_sem:
up_read(&NILFS_MDT(cpfile)->mi_sem);
return ret;
}