Commit dc200a88 authored Dec 13, 2006 by David Teigland Committed by Steven Whitehouse Feb 05, 2007

[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>

parent c3780511

fs/dlm/lock.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -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);