From 403f24d3d51760a8b9368d595fa5f48c309f1a0f Mon Sep 17 00:00:00 2001 From: Josh Durgin Date: Mon, 5 Dec 2011 10:47:13 -0800 Subject: [PATCH] rbd: protect read of snapshot sequence number This is updated whenever a snapshot is added or deleted, and the snapc pointer is changed with every refresh of the header. Signed-off-by: Josh Durgin Reviewed-by: Alex Elder Reviewed-by: Yehuda Sadeh --- drivers/block/rbd.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index a75fe93a25b..5ab9f55d3e0 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -1684,7 +1684,9 @@ static int rbd_header_add_snap(struct rbd_device *dev, if (ret < 0) return ret; - dev->header.snapc->seq = new_snapid; + down_write(&dev->header_rwsem); + dev->header.snapc->seq = new_snapid; + up_write(&dev->header_rwsem); return 0; bad: -- 2.20.1