md:Check if call to thaw_bdev fails in unlock_fs

This adds a check to the function unlock_fs to check if the call
to thaw_bdev failed by returning a return code and if so print
on the log level of KERN_CRIT that the thaw has failed on the
passed device structure pointer's name before returnin immediately
to this function's caller.

Signed-off-by: Nicholas Krause <redacted>
---
 drivers/md/dm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index ab37ae1..20ccc36 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c

@@ -3152,7 +3152,11 @@ static void unlock_fs(struct mapped_device *md)
 	if (!test_bit(DMF_FROZEN, &md->flags))
 		return;
 
-	thaw_bdev(md->bdev, md->frozen_sb);
+	if (!thaw_bdev(md->bdev, md->frozen_sb)) {
+		pr_crit("Thaw failed on the file device %s\n", md->name);
+		return;
+	}
+
 	md->frozen_sb = NULL;
 	clear_bit(DMF_FROZEN, &md->flags);
 }

-- 
2.1.4