Commit ac7cf246 authored by Joseph Qi's avatar Joseph Qi Committed by Linus Torvalds
Browse files

ocfs2/dlm: fix race between convert and recovery

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.

        list_move_tail(&lock->list, &res->converting);
        lock->convert_pending = 1;

        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.

        lock->convert_pending = 0;
        if (status != DLM_NORMAL)
                dlm_revert_pending_convert(res, lock);

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: default avatarJoseph Qi <>
Reported-by: default avatarYiwen Jiang <>
Reviewed-by: default avatarJunxiao Bi <>
Cc: Mark Fasheh <>
Cc: Joel Becker <>
Cc: Tariq Saeed <>
Cc: Junxiao Bi <>
Cc: <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 28888681
......@@ -262,6 +262,7 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm,
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);
......@@ -316,11 +317,19 @@ enum dlm_status dlmconvert_remote(struct dlm_ctxt *dlm,
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_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->;
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