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Subject[DLM] fix resend rcom lock [2/54]
From
Date
>From 3f75e071fc3e5479800614656492230a1ce50182 Mon Sep 17 00:00:00 2001
From: David Teigland <teigland@redhat.com>
Date: Wed, 13 Dec 2006 10:36:37 -0600
Subject: [PATCH] [DLM] fix resend rcom lock

There's a chance the new master of resource hasn't learned it's the new
master before another node sends it a lock during recovery. The node
sending the lock needs to resend if this happens.

- A sends a master lookup for resource R to C
- B sends a master lookup for resource R to C
- C receives A's lookup, assigns A to be master of R and
sends a reply back to A
- C receives B's lookup and sends a reply back to B saying
that A is the master
- B receives lookup reply from C and sends its lock for R to A
- A receives lock from B, doesn't think it's the master of R
and sends an error back to B
- A receives lookup reply from C and becomes master of R
- B gets error back from A and resends its lock back to A
(this resending is what this patch does)
- A receives lock from B, it now sees it's the master of R
and takes the lock

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

diff --git a/fs/dlm/lock.c b/fs/dlm/lock.c
index 30878de..69ada58 100644
--- a/fs/dlm/lock.c
+++ b/fs/dlm/lock.c
@@ -3571,6 +3571,14 @@ int dlm_recover_process_copy(struct dlm_ls *ls, struct dlm_rcom *rc)
lock_rsb(r);

switch (error) {
+ case -EBADR:
+ /* There's a chance the new master received our lock before
+ dlm_recover_master_reply(), this wouldn't happen if we did
+ a barrier between recover_masters and recover_locks. */
+ log_debug(ls, "master copy not ready %x r %lx %s", lkb->lkb_id,
+ (unsigned long)r, r->res_name);
+ dlm_send_rcom_lock(r, lkb);
+ goto out;
case -EEXIST:
log_debug(ls, "master copy exists %x", lkb->lkb_id);
/* fall through */
@@ -3585,7 +3593,7 @@ int dlm_recover_process_copy(struct dlm_ls *ls, struct dlm_rcom *rc)
/* an ack for dlm_recover_locks() which waits for replies from
all the locks it sends to new masters */
dlm_recovered_lock(r);
-
+ out:
unlock_rsb(r);
put_rsb(r);
dlm_put_lkb(lkb);
--
1.4.4.2


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