dlm: avoid unnecessary posix unlock

When the kernel clears flocks/plocks during close, it calls posix unlock when there are flocks but no posix locks. Without this patch, that unnecessary posix unlock is passed to userland (dlm_controld), across the cluster, and back to the kernel. This can create a lot of plock activity, even when no posix locks had been used. This patch copies the nfs approach, and skips the full posix unlock if there is no plock found during the vfs unlock phase. Signed-off-by: David Teigland <teigland@redhat.com>

dlm: avoid unnecessary posix unlock
When the kernel clears flocks/plocks during close, it calls posix unlock when there are flocks but no posix locks. Without this patch, that unnecessary posix unlock is passed to userland (dlm_controld), across the cluster, and back to the kernel. This can create a lot of plock activity, even when no posix locks had been used. This patch copies the nfs approach, and skips the full posix unlock if there is no plock found during the vfs unlock phase. Signed-off-by: David Teigland <teigland@redhat.com>
David Teigland
1 parent 31880c37c1
Showing 1 changed file with 15 additions and 3 deletions Side-by-side Diff
fs/dlm/plock.c
@@ -247,6 +247,7 @@
 	struct dlm_ls *ls;
 	struct plock_op *op;
 	int rv;
+	unsigned char fl_flags = fl->fl_flags;
  
 	ls = dlm_find_lockspace_local(lockspace);
 	if (!ls)
  
@@ -258,10 +259,19 @@
 		goto out;
 	}
  
-	if (posix_lock_file_wait(file, fl) < 0)
-		log_error(ls, "dlm_posix_unlock: vfs unlock error %llx",
-			  (unsigned long long)number);
+	/* cause the vfs unlock to return ENOENT if lock is not found */
+	fl->fl_flags |= FL_EXISTS;
  
+	rv = posix_lock_file_wait(file, fl);
+	if (rv == -ENOENT) {
+		rv = 0;
+		goto out_free;
+	}
+	if (rv < 0) {
+		log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx",
+			  rv, (unsigned long long)number);
+	}
+
 	op->info.optype		= DLM_PLOCK_OP_UNLOCK;
 	op->info.pid		= fl->fl_pid;
 	op->info.fsid		= ls->ls_global_id;
  
@@ -296,9 +306,11 @@
 	if (rv == -ENOENT)
 		rv = 0;
  
+out_free:
 	kfree(op);
 out:
 	dlm_put_lockspace(ls);
+	fl->fl_flags = fl_flags;
 	return rv;
 }
 EXPORT_SYMBOL_GPL(dlm_posix_unlock);
...	...	@@ -247,6 +247,7 @@
247	247	struct dlm_ls *ls;
248	248	struct plock_op *op;
249	249	int rv;
	250	+ unsigned char fl_flags = fl->fl_flags;
250	251
251	252	ls = dlm_find_lockspace_local(lockspace);
252	253	if (!ls)
253	254
...	...	@@ -258,10 +259,19 @@
258	259	goto out;
259	260	}
260	261
261		- if (posix_lock_file_wait(file, fl) < 0)
262		- log_error(ls, "dlm_posix_unlock: vfs unlock error %llx",
263		- (unsigned long long)number);
	262	+ /* cause the vfs unlock to return ENOENT if lock is not found */
	263	+ fl->fl_flags \|= FL_EXISTS;
264	264
	265	+ rv = posix_lock_file_wait(file, fl);
	266	+ if (rv == -ENOENT) {
	267	+ rv = 0;
	268	+ goto out_free;
	269	+ }
	270	+ if (rv < 0) {
	271	+ log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx",
	272	+ rv, (unsigned long long)number);
	273	+ }
	274	+
265	275	op->info.optype = DLM_PLOCK_OP_UNLOCK;
266	276	op->info.pid = fl->fl_pid;
267	277	op->info.fsid = ls->ls_global_id;
268	278
...	...	@@ -296,9 +306,11 @@
296	306	if (rv == -ENOENT)
297	307	rv = 0;
298	308
	309	+out_free:
299	310	kfree(op);
300	311	out:
301	312	dlm_put_lockspace(ls);
	313	+ fl->fl_flags = fl_flags;
302	314	return rv;
303	315	}
304	316	EXPORT_SYMBOL_GPL(dlm_posix_unlock);