From: Ahmed Samy <f.fallen45@gmail.com>
Date: Sun, 17 Apr 2016 05:37:09 +0000 (+0000)
Subject: dm cache metadata: fix cmd_read_lock() acquiring write lock
X-Git-Tag: firefly_0821_release~176^2~4^2~48^2~145
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=be5cbaf31cd318f8aaeeff901f6d27232dfa965f;p=firefly-linux-kernel-4.4.55.git

dm cache metadata: fix cmd_read_lock() acquiring write lock

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.fallen45@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 65ce6985f87a..3970cda10080 100644
--- 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_cache_metadata *cmd)
 
 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;