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 <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 8100701..4fc7f98 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -786,6 +786,7 @@
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 @@
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)) {