linux-kernel - [ 27/33] drbd: fix for deadlock when using automatic split-brain-recovery

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Message-Id: <20130517214919.789039630@linuxfoundation.org>
Date:	Fri, 17 May 2013 14:50:11 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Philipp Reisner <philipp.reisner@...bit.com>,
	Lars Ellenberg <lars.ellenberg@...bit.com>,
	Jens Axboe <axboe@...nel.dk>,
	Jonghwan Choi <jhbird.choi@...sung.com>
Subject: [ 27/33] drbd: fix for deadlock when using automatic split-brain-recovery

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

------------------

From: Philipp Reisner <philipp.reisner@...bit.com>

commit 7c689e63a847316c1b2500f86891b0a574ce7e69 upstream.

With an automatic after split-brain recovery policy of
"after-sb-1pri call-pri-lost-after-sb",
when trying to drbd_set_role() to R_SECONDARY,
we run into a deadlock.

This was first recognized and supposedly fixed by
2009-06-10 "Fixed a deadlock when using automatic split brain recovery when both nodes are"
replacing drbd_set_role() with drbd_change_state() in that code-path,
but the first hunk of that patch forgets to remove the drbd_set_role().

We apparently only ever tested the "two primaries" case.

Signed-off-by: Philipp Reisner <philipp.reisner@...bit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@...bit.com>
Signed-off-by: Jens Axboe <axboe@...nel.dk>
Signed-off-by: Jonghwan Choi <jhbird.choi@...sung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/block/drbd/drbd_receiver.c |    1 -
 1 file changed, 1 deletion(-)

--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -2225,7 +2225,6 @@ static int drbd_asb_recover_1p(struct dr
 		if (hg == -1 && mdev->state.role == R_PRIMARY) {
 			enum drbd_state_rv rv2;
 
-			drbd_set_role(mdev, R_SECONDARY, 0);
 			 /* drbd_change_state() does not sleep while in SS_IN_TRANSIENT_STATE,
 			  * we might be here in C_WF_REPORT_PARAMS which is transient.
 			  * we do not need to wait for the after state change work either. */


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