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Commit 81f44862 authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Philipp Reisner
Browse files

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: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
parent 38a05c16

drivers/block/drbd/drbd_req.c

+4 −2
Original line number Diff line number Diff line
@@ -822,6 +822,7 @@ int __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long s 
	int local, remote, send_oos = 0;

	int err;

	int ret = 0;

	union drbd_dev_state s;



	/* allocate outside of all locks; */

	req = drbd_req_new(mdev, bio);
@@ -884,8 +885,9 @@ int __drbd_make_request(struct drbd_conf *mdev, struct bio *bio, unsigned long s 
		drbd_al_begin_io(mdev, &req->i);

	}



	remote = remote && drbd_should_do_remote(mdev->state);

	send_oos = rw == WRITE && drbd_should_send_out_of_sync(mdev->state);

	s = mdev->state;

	remote = remote && drbd_should_do_remote(s);

	send_oos = rw == WRITE && drbd_should_send_out_of_sync(s);

	D_ASSERT(!(remote && send_oos));



	if (!(local || remote) && !drbd_suspended(mdev)) {