From 27bf6305cf85cb474295c300c99cc3d10d68f50a Mon Sep 17 00:00:00 2001 From: Tariq Saeed Date: Mon, 23 Jun 2014 13:22:08 -0700 Subject: [PATCH] ocfs2: fix deadlock when two nodes are converting same lock from PR to EX and idletimeout closes conn Orabug: 18639535 Two node cluster and both nodes hold a lock at PR level and both want to convert to EX at the same time. Master node 1 has sent BAST and then closes the connection due to idletime out. Node 0 receives BAST, sends unlock req with cancel flag but gets error -ENOTCONN. The problem is this error is ignored in dlm_send_remote_unlock_request() on the **incorrect** assumption that the master is dead. See NOTE in comment why it returns DLM_NORMAL. Upon getting DLM_NORMAL, node 0 proceeds to sends convert (without cancel flg) which fails with -ENOTCONN. waits 5 sec and resends. This time gets DLM_IVLOCKID from the master since lock not found in grant, it had been moved to converting queue in response to conv PR->EX req. No way out. Node 1 (master) Node 0 ============== ====== lock mode PR PR convert PR -> EX mv grant -> convert and que BAST ... <-------- convert PR -> EX convert que looks like this: ((node 1, PR -> EX) (node 0, PR -> EX)) ... BAST (want PR -> NL) ------------------> ... idle timout, conn closed ... In response to BAST, sends unlock with cancel convert flag gets -ENOTCONN. Ignores and sends remote convert request gets -ENOTCONN, waits 5 Sec, retries ... reconnects <----------------- convert req goes through on next try does not find lock on grant que status DLM_IVLOCKID ------------------> ... No way out. Fix is to keep retrying unlock with cancel flag until it succeeds or the master dies. Signed-off-by: Tariq Saeed Reviewed-by: Mark Fasheh Cc: Joel Becker Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/ocfs2/dlm/dlmunlock.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) diff --git a/fs/ocfs2/dlm/dlmunlock.c b/fs/ocfs2/dlm/dlmunlock.c index 5698b52..2e3c9db 100644 --- a/fs/ocfs2/dlm/dlmunlock.c +++ b/fs/ocfs2/dlm/dlmunlock.c @@ -191,7 +191,9 @@ static enum dlm_status dlmunlock_common(struct dlm_ctxt *dlm, DLM_UNLOCK_CLEAR_CONVERT_TYPE); } else if (status == DLM_RECOVERING || status == DLM_MIGRATING || - status == DLM_FORWARD) { + status == DLM_FORWARD || + status == DLM_NOLOCKMGR + ) { /* must clear the actions because this unlock * is about to be retried. cannot free or do * any list manipulation. */ @@ -200,7 +202,8 @@ static enum dlm_status dlmunlock_common(struct dlm_ctxt *dlm, res->lockname.name, status==DLM_RECOVERING?"recovering": (status==DLM_MIGRATING?"migrating": - "forward")); + (status == DLM_FORWARD ? "forward" : + "nolockmanager"))); actions = 0; } if (flags & LKM_CANCEL) @@ -364,7 +367,10 @@ static enum dlm_status dlm_send_remote_unlock_request(struct dlm_ctxt *dlm, * updated state to the recovery master. this thread * just needs to finish out the operation and call * the unlockast. */ - ret = DLM_NORMAL; + if (dlm_is_node_dead(dlm, owner)) + ret = DLM_NORMAL; + else + ret = DLM_NOLOCKMGR; } else { /* something bad. this will BUG in ocfs2 */ ret = dlm_err_to_dlm_status(tmpret); @@ -638,7 +644,9 @@ retry: if (status == DLM_RECOVERING || status == DLM_MIGRATING || - status == DLM_FORWARD) { + status == DLM_FORWARD || + status == DLM_NOLOCKMGR) { + /* We want to go away for a tiny bit to allow recovery * / migration to complete on this resource. I don't * know of any wait queue we could sleep on as this @@ -650,7 +658,7 @@ retry: msleep(50); mlog(0, "retrying unlock due to pending recovery/" - "migration/in-progress\n"); + "migration/in-progress/reconnect\n"); goto retry; } -- 2.7.4