From: Philipp Reisner Date: Mon, 16 Jan 2012 11:14:01 +0000 (+0100) Subject: drbd: Fix a potential race that could case data inconsistency X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=fc28845bc005995b41ae8c83c7922d088f0ad228;p=linux-beck.git drbd: Fix a potential race that could case data inconsistency When we have a write request and a state change C_WF_BITMAP_S -> C_SYNC_SOURCE at the same time, and it happens that the line remote = remote && drbd_should_do_remote(s); stills sees C_WF_BITMAP_S, and send_oos = rw == WRITE && drbd_should_send_oos(s); already sees C_SYNC_SOURCE both are 0. This causes the write to not be mirrored, but marked as out-of-sync on the Sync_Source node. Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c index 810070146862..4fc7f98d9856 100644 --- a/drivers/block/drbd/drbd_req.c +++ b/drivers/block/drbd/drbd_req.c @@ -786,6 +786,7 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio, uns int local, remote, send_oos = 0; int err = -EIO; int ret = 0; + union drbd_state s; /* allocate outside of all locks; */ req = drbd_req_new(mdev, bio); @@ -847,8 +848,9 @@ static int drbd_make_request_common(struct drbd_conf *mdev, struct bio *bio, uns drbd_al_begin_io(mdev, sector); } - remote = remote && drbd_should_do_remote(mdev->state); - send_oos = rw == WRITE && drbd_should_send_oos(mdev->state); + s = mdev->state; + remote = remote && drbd_should_do_remote(s); + send_oos = rw == WRITE && drbd_should_send_oos(s); D_ASSERT(!(remote && send_oos)); if (!(local || remote) && !is_susp(mdev->state)) {