[PATCH 4.5 024/200] dm cache metadata: fix cmd_read_lock() acquiring write lock

[Greg Kroah-Hartman]

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ahmed Samy <f.falle...@gmail.com>

commit 6545b60baaf880b0cd29a5e89dbe745a06027e89 upstream.

Commit 9567366fefdd ("dm cache metadata: fix READ_LOCK macros and
cleanup WRITE_LOCK macros") uses down_write() instead of down_read() in
cmd_read_lock(), yet up_read() is used to release the lock in
READ_UNLOCK().  Fix it.

Fixes: 9567366fefdd ("dm cache metadata: fix READ_LOCK macros and cleanup 
WRITE_LOCK macros")
Signed-off-by: Ahmed Samy <f.falle...@gmail.com>
Signed-off-by: Mike Snitzer <snit...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/md/dm-cache-metadata.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -894,9 +894,9 @@ static bool cmd_write_lock(struct dm_cac
 
 static bool cmd_read_lock(struct dm_cache_metadata *cmd)
 {
-       down_write(&cmd->root_lock);
+       down_read(&cmd->root_lock);
        if (cmd->fail_io) {
-               up_write(&cmd->root_lock);
+               up_read(&cmd->root_lock);
                return false;
        }
        return true;