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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 8d400b81cc ("ocfs2/dlm: Clean up refmap
helpers").  Since lockres is new, it doesn't not require the
&res->spinlock.  So remove it.

Fixes: 8d400b81cc ("ocfs2/dlm: Clean up refmap helpers")
Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Reviewed-by: joyce.xue <xuejiufei@huawei.com>
Reported-by: Guozhonghua <guozhonghua@h3c.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Joseph Qi 2014-09-25 16:05:16 -07:00 committed by Linus Torvalds
parent 56d7acc792
commit 5760a97c71
1 changed files with 10 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
fs/ocfs2/dlm/dlmmaster.c
View File

@ -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 @@ lookup:
/* 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