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authorJun'ichi Nomura <j-nomura@ce.jp.nec.com>2010-01-29 09:56:22 +0900
committerAl Viro <viro@zeniv.linux.org.uk>2010-02-07 03:06:21 -0500
commit4b06e5b9ad8abb20105b2b25e42c509ebe9b2d76 (patch)
treea151e21fef671e9d046a6c456d2f048eea56fb99 /fs/block_dev.c
parent8dd5ca532c2d2c2b85f16bc038ebfff05b8853e1 (diff)
freeze_bdev: don't deactivate successfully frozen MS_RDONLY sb
Thanks Thomas and Christoph for testing and review. I removed 'smp_wmb()' before up_write from the previous patch, since up_write() should have necessary ordering constraints. (I.e. the change of s_frozen is visible to others after up_write) I'm quite sure the change is harmless but if you are uncomfortable with Tested-by/Reviewed-by on the modified patch, please remove them. If MS_RDONLY, freeze_bdev should just up_write(s_umount) instead of deactivate_locked_super(). Also, keep sb->s_frozen consistent so that remount can check the frozen state. Otherwise a crash reported here can happen: http://lkml.org/lkml/2010/1/16/37 http://lkml.org/lkml/2010/1/28/53 This patch should be applied for 2.6.32 stable series, too. Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Thomas Backlund <tmb@mandriva.org> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: stable@kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/block_dev.c')
-rw-r--r--fs/block_dev.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 73d6a735b8f..d11d0289f3d 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -246,7 +246,8 @@ struct super_block *freeze_bdev(struct block_device *bdev)
if (!sb)
goto out;
if (sb->s_flags & MS_RDONLY) {
- deactivate_locked_super(sb);
+ sb->s_frozen = SB_FREEZE_TRANS;
+ up_write(&sb->s_umount);
mutex_unlock(&bdev->bd_fsfreeze_mutex);
return sb;
}
@@ -307,7 +308,7 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
BUG_ON(sb->s_bdev != bdev);
down_write(&sb->s_umount);
if (sb->s_flags & MS_RDONLY)
- goto out_deactivate;
+ goto out_unfrozen;
if (sb->s_op->unfreeze_fs) {
error = sb->s_op->unfreeze_fs(sb);
@@ -321,11 +322,11 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
}
}
+out_unfrozen:
sb->s_frozen = SB_UNFROZEN;
smp_wmb();
wake_up(&sb->s_wait_unfrozen);
-out_deactivate:
if (sb)
deactivate_locked_super(sb);
out_unlock: