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Subject[PATCH 1/5] fsfreeze: Prevent emergency thaw from looping infinitely
Date
From: Dave Chinner <dchinner@redhat.com>

The thawing of a filesystem through sysrq-j loops infinitely as it
incorrectly detects a thawed filesytsem as frozen and tries to
unfreeze repeatedly. This is a regression caused by
4504230a71566785a05d3e6b53fa1ee071b864eb ("freeze_bdev: grab active
reference to frozen superblocks") in that it no longer returned
-EINVAL for superblocks that were not frozen.

Return -EINVAL when the filesystem is already unfrozen to avoid this
problem.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/block_dev.c | 13 +++++--------
1 files changed, 5 insertions(+), 8 deletions(-)
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 7346c96..366ac38 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -276,22 +276,19 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
if (!bdev->bd_fsfreeze_count)
goto out;

- error = 0;
- if (--bdev->bd_fsfreeze_count > 0)
+ if (!sb)
goto out;

- if (!sb)
+ error = 0;
+ if (--bdev->bd_fsfreeze_count > 0)
goto out;

error = thaw_super(sb);
- if (error) {
+ if (error)
bdev->bd_fsfreeze_count++;
- mutex_unlock(&bdev->bd_fsfreeze_mutex);
- return error;
- }
out:
mutex_unlock(&bdev->bd_fsfreeze_mutex);
- return 0;
+ return error;
}
EXPORT_SYMBOL(thaw_bdev);

--
1.7.1


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