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Commit 5760a97c authored by Joseph Qi's avatar Joseph Qi Committed by Linus Torvalds
Browse files

ocfs2/dlm: do not get resource spinlock if lockres is new 

There is a deadlock case which reported by Guozhonghua:
  https://oss.oracle.com/pipermail/ocfs2-devel/2014-September/010079.html



This case is caused by &res->spinlock and &dlm->master_lock
misordering in different threads.

It was introduced by commit 8d400b81 ("ocfs2/dlm: Clean up refmap
helpers").  Since lockres is new, it doesn't not require the
&res->spinlock.  So remove it.

Fixes: 8d400b81 ("ocfs2/dlm: Clean up refmap helpers")
Signed-off-by: default avatarJoseph Qi <joseph.qi@huawei.com>
Reviewed-by: default avatarjoyce.xue <xuejiufei@huawei.com>
Reported-by: default avatarGuozhonghua <guozhonghua@h3c.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 56d7acc7

fs/ocfs2/dlm/dlmmaster.c

+10 −8
Original line number Diff line number Diff line
@@ -655,12 +655,9 @@ void dlm_lockres_clear_refmap_bit(struct dlm_ctxt *dlm, 
	clear_bit(bit, res->refmap);

}





void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,

static void __dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,

				   struct dlm_lock_resource *res)

{

	assert_spin_locked(&res->spinlock);



	res->inflight_locks++;



	mlog(0, "%s: res %.*s, inflight++: now %u, %ps()\n", dlm->name,
@@ -668,6 +665,13 @@ void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm, 
	     __builtin_return_address(0));

}



void dlm_lockres_grab_inflight_ref(struct dlm_ctxt *dlm,

				   struct dlm_lock_resource *res)

{

	assert_spin_locked(&res->spinlock);

	__dlm_lockres_grab_inflight_ref(dlm, res);

}



void dlm_lockres_drop_inflight_ref(struct dlm_ctxt *dlm,

				   struct dlm_lock_resource *res)

{
@@ -894,10 +898,8 @@ struct dlm_lock_resource * dlm_get_lock_resource(struct dlm_ctxt *dlm, 
	/* finally add the lockres to its hash bucket */

	__dlm_insert_lockres(dlm, res);



	/* Grab inflight ref to pin the resource */

	spin_lock(&res->spinlock);

	dlm_lockres_grab_inflight_ref(dlm, res);

	spin_unlock(&res->spinlock);

	/* since this lockres is new it doesn't not require the spinlock */

	__dlm_lockres_grab_inflight_ref(dlm, res);



	/* get an extra ref on the mle in case this is a BLOCK

	 * if so, the creator of the BLOCK may try to put the last