fs/block_dev.c: return the right error in thaw_bdev()

When triggering thaw-filesystems via magic sysrq, the system enters a
loop in do_thaw_one(), as thaw_bdev() still returns success if
bd_fsfreeze_count == 0. To fix this, let thaw_bdev() always return
error (and simplify the code a bit at the same time).

Reviewed-by: Eric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 2 insertions, 5 deletions

diff --git a/fs/block_dev.c b/fs/block_dev.c
index a516568f63b6..376e4e426324 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -299,14 +299,11 @@ int thaw_bdev(struct block_device *bdev, struct super_block *sb)
                 error = sb->s_op->thaw_super(sb);
         else
                 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);