lkml.org 
[lkml]   [2016]   [Apr]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 3.2 057/115] ocfs2/dlm: fix race between convert and recovery
3.2.80-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Joseph Qi <joseph.qi@huawei.com>

commit ac7cf246dfdbec3d8fed296c7bf30e16f5099dac upstream.

There is a race window between dlmconvert_remote and
dlm_move_lockres_to_recovery_list, which will cause a lock with
OCFS2_LOCK_BUSY in grant list, thus system hangs.

dlmconvert_remote
{
spin_lock(&res->spinlock);
list_move_tail(&lock->list, &res->converting);
lock->convert_pending = 1;
spin_unlock(&res->spinlock);

status = dlm_send_remote_convert_request();
>>>>>> race window, master has queued ast and return DLM_NORMAL,
and then down before sending ast.
this node detects master down and calls
dlm_move_lockres_to_recovery_list, which will revert the
lock to grant list.
Then OCFS2_LOCK_BUSY won't be cleared as new master won't
send ast any more because it thinks already be authorized.

spin_lock(&res->spinlock);
lock->convert_pending = 0;
if (status != DLM_NORMAL)
dlm_revert_pending_convert(res, lock);
spin_unlock(&res->spinlock);
}

In this case, check if res->state has DLM_LOCK_RES_RECOVERING bit set
(res is still in recovering) or res master changed (new master has
finished recovery), reset the status to DLM_RECOVERING, then it will
retry convert.

Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Reported-by: Yiwen Jiang <jiangyiwen@huawei.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Tariq Saeed <tariq.x.saeed@oracle.com>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/ocfs2/dlm/dlmconvert.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

--- a/fs/ocfs2/dlm/dlmconvert.c
+++ b/fs/ocfs2/dlm/dlmconvert.c
@@ -265,6 +265,7 @@ enum dlm_status dlmconvert_remote(struct
struct dlm_lock *lock, int flags, int type)
{
enum dlm_status status;
+ u8 old_owner = res->owner;

mlog(0, "type=%d, convert_type=%d, busy=%d\n", lock->ml.type,
lock->ml.convert_type, res->state & DLM_LOCK_RES_IN_PROGRESS);
@@ -319,11 +320,19 @@ enum dlm_status dlmconvert_remote(struct
spin_lock(&res->spinlock);
res->state &= ~DLM_LOCK_RES_IN_PROGRESS;
lock->convert_pending = 0;
- /* if it failed, move it back to granted queue */
+ /* if it failed, move it back to granted queue.
+ * if master returns DLM_NORMAL and then down before sending ast,
+ * it may have already been moved to granted queue, reset to
+ * DLM_RECOVERING and retry convert */
if (status != DLM_NORMAL) {
if (status != DLM_NOTQUEUED)
dlm_error(status);
dlm_revert_pending_convert(res, lock);
+ } else if ((res->state & DLM_LOCK_RES_RECOVERING) ||
+ (old_owner != res->owner)) {
+ mlog(0, "res %.*s is in recovering or has been recovered.\n",
+ res->lockname.len, res->lockname.name);
+ status = DLM_RECOVERING;
}
bail:
spin_unlock(&res->spinlock);
\
 
 \ /
  Last update: 2016-04-27 02:01    [W:0.318 / U:2.824 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site