linux-kernel - [PATCH 4.2.y-ckt 57/93] dm cache metadata: fix cmd_read

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Message-Id: <1461694653-29506-58-git-send-email-kamal@canonical.com>
Date:	Tue, 26 Apr 2016 11:16:57 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Ahmed Samy <f.fallen45@...il.com>,
	Mike Snitzer <snitzer@...hat.com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 57/93] dm cache metadata: fix cmd_read_lock() acquiring write lock

4.2.8-ckt9 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Ahmed Samy <f.fallen45@...il.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.fallen45@...il.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/md/dm-cache-metadata.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-cache-metadata.c b/drivers/md/dm-cache-metadata.c
index 141b9bc..d00d5bb 100644
--- a/drivers/md/dm-cache-metadata.c
+++ b/drivers/md/dm-cache-metadata.c
@@ -890,9 +890,9 @@ 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;
-- 
2.7.4