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nilfs2: disallow remount of snapshot from/to a regular mount 

Snapshots and regular ro/rw mounts are essentially-different within
the meaning whether the checkpoint is static or not and is marked with
a snapshot flag or not.

The current implemenation, however, allows to remount a snapshot to a
regular rw-mount if the checkpoint number equals the latest one.

This transition is actually impossible since changing a checkpoint to
a snapshot makes another checkpoint, thus the condition is never
satisfied.

This fixes the weird state of affairs, and specifically separates
snapshots and regular rw/ro-mounts.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
hifive-unleashed-5.1
Ryusuke Konishi 2010-05-09 21:51:53 +09:00
parent cdce214e39
commit d240e06713
1 changed files with 23 additions and 34 deletions
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57
fs/nilfs2/super.c
View File

@ -754,9 +754,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
goto failed_sbi;
}
cno = sbi->s_snapshot_cno;
} else
/* Read-only mount */
sbi->s_snapshot_cno = cno;
}
}
err = nilfs_attach_checkpoint(sbi, cno);
@ -825,7 +823,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
struct the_nilfs *nilfs = sbi->s_nilfs;
unsigned long old_sb_flags;
struct nilfs_mount_options old_opts;
int err;
int was_snapshot, err;
lock_kernel();
@ -833,6 +831,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
old_sb_flags = sb->s_flags;
old_opts.mount_opt = sbi->s_mount_opt;
old_opts.snapshot_cno = sbi->s_snapshot_cno;
was_snapshot = nilfs_test_opt(sbi, SNAPSHOT);
if (!parse_options(data, sb)) {
err = -EINVAL;
@ -840,20 +839,32 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
}
sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
if ((*flags & MS_RDONLY) &&
sbi->s_snapshot_cno != old_opts.snapshot_cno) {
printk(KERN_WARNING "NILFS (device %s): couldn't "
"remount to a different snapshot.\n",
sb->s_id);
err = -EINVAL;
goto restore_opts;
err = -EINVAL;
if (was_snapshot) {
if (!(*flags & MS_RDONLY)) {
printk(KERN_ERR "NILFS (device %s): cannot remount "
"snapshot read/write.\n",
sb->s_id);
goto restore_opts;
} else if (sbi->s_snapshot_cno != old_opts.snapshot_cno) {
printk(KERN_ERR "NILFS (device %s): cannot "
"remount to a different snapshot.\n",
sb->s_id);
goto restore_opts;
}
} else {
if (nilfs_test_opt(sbi, SNAPSHOT)) {
printk(KERN_ERR "NILFS (device %s): cannot change "
"a regular mount to a snapshot.\n",
sb->s_id);
goto restore_opts;
}
}
if (!nilfs_valid_fs(nilfs)) {
printk(KERN_WARNING "NILFS (device %s): couldn't "
"remount because the filesystem is in an "
"incomplete recovery state.\n", sb->s_id);
err = -EINVAL;
goto restore_opts;
}
@ -864,9 +875,6 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
nilfs_detach_segment_constructor(sbi);
sb->s_flags |= MS_RDONLY;
sbi->s_snapshot_cno = nilfs_last_cno(nilfs);
/* nilfs_set_opt(sbi, SNAPSHOT); */
/*
* Remounting a valid RW partition RDONLY, so set
* the RDONLY flag and then mark the partition as valid again.
@ -885,24 +893,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
* store the current valid flag. (It may have been changed
* by fsck since we originally mounted the partition.)
*/
if (nilfs->ns_current && nilfs->ns_current != sbi) {
printk(KERN_WARNING "NILFS (device %s): couldn't "
"remount because an RW-mount exists.\n",
sb->s_id);
err = -EBUSY;
goto restore_opts;
}
if (sbi->s_snapshot_cno != nilfs_last_cno(nilfs)) {
printk(KERN_WARNING "NILFS (device %s): couldn't "
"remount because the current RO-mount is not "
"the latest one.\n",
sb->s_id);
err = -EINVAL;
goto restore_opts;
}
sb->s_flags &= ~MS_RDONLY;
nilfs_clear_opt(sbi, SNAPSHOT);
sbi->s_snapshot_cno = 0;
err = nilfs_attach_segment_constructor(sbi);
if (err)
@ -911,8 +902,6 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
down_write(&nilfs->ns_sem);
nilfs_setup_super(sbi);
up_write(&nilfs->ns_sem);
nilfs->ns_current = sbi;
}
out:
up_write(&nilfs->ns_super_sem);