Commit bba1cb17 authored Aug 06, 2014 by Tariq Saeed Committed by Linus Torvalds Aug 06, 2014

ocfs2: race between umount and unfinished remastering during recovery



Orabug: 19074140

When umount is issued during recovery on the new master that has not
finished remastering locks, it triggers BUG() in
dlm_send_mig_lockres_msg().  Here is the situation:

 1) node A has a lock on resource X mastered by node B.

 2) node B dies ->  node A sets recovering flag for res X

 3) Node C becomes the new master for resources owned by the
    dead node and is remastering locks of the dead node but
    has not finished the remastering process yet.

 4) umount is issued on node C.

 5) During processing of umount, ignoring unfished recovery,
    node C attempts to migrate resource X to node A.

 6) node A finds res X in DLM_LOCK_RES_RECOVERING state, considers
    it a logic error and sends back -EFAULT.

 7) node C asserts BUG() upon seeing EFAULT resp from node B.

Fix is to delay migrating res X till remastering is finished at which
point recovering flag will be cleared on both A and C.

Signed-off-by: Tariq Saeed <tariq.x.saeed@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 7567c148

fs/ocfs2/dlm/dlmmaster.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -2405,6 +2405,10 @@ static int dlm_is_lockres_migrateable(struct dlm_ctxt *dlm,
		if (res->state & DLM_LOCK_RES_MIGRATING)
		return 0;

		/* delay migration when the lockres is in RECOCERING state */
		if (res->state & DLM_LOCK_RES_RECOVERING)
		return 0;

		if (res->owner != dlm->node_num)
		return 0;

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