freeze_bdev() with read-only mounted device(*) does not change sb->s_frozen
from SB_UNFROZEN to SB_FREEZE_TRANS.
Because of this behavior, xfs_freeze can break read-only filesystem.
Because xfs_thaw does nothing for the filesystem whose sb->s_frozen is
SB_UNFROZEN. So frozen read-only XFS filesystem will never be unfrozen.
Thus we cannot do any unmount/remount operations for that filesystem.
This patch updates sb->s_frozen when freeze_bdev() is called for read-only
mounted device, too.
(*) freezing read-only filesystem is not so pointless. Because it can
prevent from someone trying to remount read/write while freezing.
Cc: David Chinner <[email protected]>
Cc: Tim Shimmin <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Akinobu Mita <[email protected]>
---
fs/buffer.c | 25 ++++++++++++++++---------
1 file changed, 16 insertions(+), 9 deletions(-)
Index: 2.6-git/fs/buffer.c
===================================================================
--- 2.6-git.orig/fs/buffer.c
+++ 2.6-git/fs/buffer.c
@@ -190,21 +190,28 @@ struct super_block *freeze_bdev(struct b
down(&bdev->bd_mount_sem);
sb = get_super(bdev);
- if (sb && !(sb->s_flags & MS_RDONLY)) {
- sb->s_frozen = SB_FREEZE_WRITE;
- smp_wmb();
-
- __fsync_super(sb);
+ if (!sb)
+ goto out;
+ if (sb->s_flags & MS_RDONLY) {
sb->s_frozen = SB_FREEZE_TRANS;
smp_wmb();
+ goto out;
+ }
- sync_blockdev(sb->s_bdev);
+ sb->s_frozen = SB_FREEZE_WRITE;
+ smp_wmb();
- if (sb->s_op->write_super_lockfs)
- sb->s_op->write_super_lockfs(sb);
- }
+ __fsync_super(sb);
+
+ sb->s_frozen = SB_FREEZE_TRANS;
+ smp_wmb();
+ sync_blockdev(sb->s_bdev);
+
+ if (sb->s_op->write_super_lockfs)
+ sb->s_op->write_super_lockfs(sb);
+out:
sync_blockdev(bdev);
return sb; /* thaw_bdev releases s->s_umount and bd_mount_sem */
}
-
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