Attachment 153038 Details for Bug 234086 – patch posted to rhkernel on 04/19

patch posted to rhkernel on 04/19

dlm-fix-alt-modes.patch (text/plain), 4.89 KB, created by David Teigland on 2007-04-19 17:38:02 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: David Teigland

Created: 2007-04-19 17:38:02 UTC

Size: 4.89 KB

patch

obsolete

>[PATCH] dlm: fix mode munging
>
>bz 234086
>
>There are flags to enable two specialized features in the dlm:
>
>1. CONVDEADLK causes the dlm to resolve conversion deadlocks internally by
>   changing the granted mode of locks to NL.
>2. ALTPR/ALTCW cause the dlm to change the requested mode of locks to PR
>   or CW to grant them if the main mode can't be granted.
>
>GFS direct i/o exercises both of these features, especially when mixed
>with buffered i/o.  The dlm has problems with them.
>
>The first problem is on the master node. If it demotes a lock as a part of
>converting it, the actual step of converting the lock isn't being done
>after the demotion, the lock is just left sitting on the granted queue
>with a granted mode of NL.  I think the mistaken assumption was that the call
>to grant_pending_locks() would grant it, but that function naturally doesn't
>look at locks on the granted queue.
>
>The second problem is on the process node.  If the master either demotes
>or gives an altmode, the munging of the gr/rq modes is never done in the
>process copy of the lock, leaving the master/process copies out of sync.
>
>Index: linux-quilt/fs/dlm/lock.c
>===================================================================
>--- linux-quilt.orig/fs/dlm/lock.c	2007-04-19 10:09:59.000000000 -0500
>+++ linux-quilt/fs/dlm/lock.c	2007-04-19 10:12:44.000000000 -0500
>@@ -224,6 +224,16 @@
> 	return (lkb->lkb_sbflags & DLM_SBF_DEMOTED);
> }
> 
>+static inline int is_altmode(struct dlm_lkb *lkb)
>+{
>+	return (lkb->lkb_sbflags & DLM_SBF_ALTMODE);
>+}
>+
>+static inline int is_granted(struct dlm_lkb *lkb)
>+{
>+	return (lkb->lkb_status == DLM_LKSTS_GRANTED);
>+}
>+
> static inline int is_remote(struct dlm_rsb *r)
> {
> 	DLM_ASSERT(r->res_nodeid >= 0, dlm_print_rsb(r););
>@@ -1191,6 +1201,50 @@
> 		queue_cast(r, lkb, 0);
> }
> 
>+/* The special CONVDEADLK, ALTPR and ALTCW flags allow the master to
>+   change the granted/requested modes.  We're munging things accordingly in
>+   the process copy.
>+   CONVDEADLK: our grmode may have been forced down to NL to resolve a
>+   conversion deadlock
>+   ALTPR/ALTCW: our rqmode may have been changed to PR or CW to become
>+   compatible with other granted locks */
>+
>+static void munge_demoted(struct dlm_lkb *lkb, struct dlm_message *ms)
>+{
>+	if (ms->m_type != DLM_MSG_CONVERT_REPLY) {
>+		log_print("munge_demoted %x invalid reply type %d",
>+			  lkb->lkb_id, ms->m_type);
>+		return;
>+	}
>+
>+	if (lkb->lkb_rqmode == DLM_LOCK_IV || lkb->lkb_grmode == DLM_LOCK_IV) {
>+		log_print("munge_demoted %x invalid modes gr %d rq %d",
>+			  lkb->lkb_id, lkb->lkb_grmode, lkb->lkb_rqmode);
>+		return;
>+	}
>+
>+	lkb->lkb_grmode = DLM_LOCK_NL;
>+}
>+
>+static void munge_altmode(struct dlm_lkb *lkb, struct dlm_message *ms)
>+{
>+	if (ms->m_type != DLM_MSG_REQUEST_REPLY &&
>+	    ms->m_type != DLM_MSG_GRANT) {
>+		log_print("munge_altmode %x invalid reply type %d",
>+			  lkb->lkb_id, ms->m_type);
>+		return;
>+	}
>+
>+	if (lkb->lkb_exflags & DLM_LKF_ALTPR)
>+		lkb->lkb_rqmode = DLM_LOCK_PR;
>+	else if (lkb->lkb_exflags & DLM_LKF_ALTCW)
>+		lkb->lkb_rqmode = DLM_LOCK_CW;
>+	else {
>+		log_print("munge_altmode invalid exflags %x", lkb->lkb_exflags);
>+		dlm_print_lkb(lkb);
>+	}
>+}
>+
> static inline int first_in_list(struct dlm_lkb *lkb, struct list_head *head)
> {
> 	struct dlm_lkb *first = list_entry(head->next, struct dlm_lkb,
>@@ -1965,9 +2019,24 @@
> 		goto out;
> 	}
> 
>-	if (can_be_queued(lkb)) {
>-		if (is_demoted(lkb))
>+	/* is_demoted() means the can_be_granted() above set the grmode
>+	   to NL, and left us on the granted queue.  This auto-demotion
>+	   (due to CONVDEADLK) might mean other locks, and/or this lock, are
>+	   now grantable.  We have to try to grant other converting locks
>+	   before we try again to grant this one. */
>+
>+	if (is_demoted(lkb)) {
>+		grant_pending_convert(r, DLM_LOCK_IV);
>+		if (_can_be_granted(r, lkb, 1)) {
>+			grant_lock(r, lkb);
>+			queue_cast(r, lkb, 0);
> 			grant_pending_locks(r);
>+			goto out;
>+		}
>+		/* else fall through and move to convert queue */
>+	}
>+
>+	if (can_be_queued(lkb)) {
> 		error = -EINPROGRESS;
> 		del_lkb(r, lkb);
> 		add_lkb(r, lkb, DLM_LKSTS_CONVERT);
>@@ -2908,6 +2977,8 @@
> 	lock_rsb(r);
> 
> 	receive_flags_reply(lkb, ms);
>+	if (is_altmode(lkb))
>+		munge_altmode(lkb, ms);
> 	grant_lock_pc(r, lkb, ms);
> 	queue_cast(r, lkb, 0);
> 
>@@ -3038,6 +3109,8 @@
> 		/* request was queued or granted on remote master */
> 		receive_flags_reply(lkb, ms);
> 		lkb->lkb_remid = ms->m_lkid;
>+		if (is_altmode(lkb))
>+			munge_altmode(lkb, ms);
> 		if (result)
> 			add_lkb(r, lkb, DLM_LKSTS_WAITING);
> 		else {
>@@ -3101,6 +3174,9 @@
> 
> 	case -EINPROGRESS:
> 		/* convert was queued on remote master */
>+		receive_flags_reply(lkb, ms);
>+		if (is_demoted(lkb))
>+			munge_demoted(lkb, ms);
> 		del_lkb(r, lkb);
> 		add_lkb(r, lkb, DLM_LKSTS_CONVERT);
> 		break;
>@@ -3108,6 +3184,8 @@
> 	case 0:
> 		/* convert was granted on remote master */
> 		receive_flags_reply(lkb, ms);
>+		if (is_demoted(lkb))
>+			munge_demoted(lkb, ms);
> 		grant_lock_pc(r, lkb, ms);
> 		queue_cast(r, lkb, 0);
> 		break;

Actions: View

Attachments on bug 234086: 153038 | 153444