staging: lustre: ldlm: improve ldlm_lock_create() return value

ldlm_lock_create() and ldlm_resource_get() always return NULL as
error reporting and "NULL" is interpretted as ENOMEM incorrectly
sometimes. This patch fixes this problem by using ERR_PTR() rather
than NULL.

Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4524
Reviewed-on: http://review.whamcloud.com/9004
Reviewed-by: Bobi Jam <bobijam@gmail.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 7 insertions, 18 deletions

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c b/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
index 5866b00..c37a7b0 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_resource.c
@@ -1088,7 +1088,7 @@ ldlm_resource_get(struct ldlm_namespace *ns, struct ldlm_resource *parent,
 		  int create)
 {
 	struct hlist_node     *hnode;
-	struct ldlm_resource *res;
+	struct ldlm_resource *res = NULL;
 	struct cfs_hash_bd	 bd;
 	__u64		 version;
 	int		      ns_refcount = 0;
@@ -1101,31 +1101,20 @@ ldlm_resource_get(struct ldlm_namespace *ns, struct ldlm_resource *parent,
 	hnode = cfs_hash_bd_lookup_locked(ns->ns_rs_hash, &bd, (void *)name);
 	if (hnode) {
 		cfs_hash_bd_unlock(ns->ns_rs_hash, &bd, 0);
-		res = hlist_entry(hnode, struct ldlm_resource, lr_hash);
-		/* Synchronize with regard to resource creation. */
-		if (ns->ns_lvbo && ns->ns_lvbo->lvbo_init) {
-			mutex_lock(&res->lr_lvb_mutex);
-			mutex_unlock(&res->lr_lvb_mutex);
-		}
-
-		if (unlikely(res->lr_lvb_len < 0)) {
-			ldlm_resource_putref(res);
-			res = NULL;
-		}
-		return res;
+		goto lvbo_init;
 	}
 
 	version = cfs_hash_bd_version_get(&bd);
 	cfs_hash_bd_unlock(ns->ns_rs_hash, &bd, 0);
 
 	if (create == 0)
-		return NULL;
+		return ERR_PTR(-ENOENT);
 
 	LASSERTF(type >= LDLM_MIN_TYPE && type < LDLM_MAX_TYPE,
 		 "type: %d\n", type);
 	res = ldlm_resource_new();
 	if (!res)
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 
 	res->lr_ns_bucket  = cfs_hash_bd_extra_get(ns->ns_rs_hash, &bd);
 	res->lr_name       = *name;
@@ -1143,7 +1132,7 @@ ldlm_resource_get(struct ldlm_namespace *ns, struct ldlm_resource *parent,
 		/* We have taken lr_lvb_mutex. Drop it. */
 		mutex_unlock(&res->lr_lvb_mutex);
 		kmem_cache_free(ldlm_resource_slab, res);
-
+lvbo_init:
 		res = hlist_entry(hnode, struct ldlm_resource, lr_hash);
 		/* Synchronize with regard to resource creation. */
 		if (ns->ns_lvbo && ns->ns_lvbo->lvbo_init) {
@@ -1153,7 +1142,7 @@ ldlm_resource_get(struct ldlm_namespace *ns, struct ldlm_resource *parent,
 
 		if (unlikely(res->lr_lvb_len < 0)) {
 			ldlm_resource_putref(res);
-			res = NULL;
+			res = ERR_PTR(res->lr_lvb_len);
 		}
 		return res;
 	}
@@ -1175,7 +1164,7 @@ ldlm_resource_get(struct ldlm_namespace *ns, struct ldlm_resource *parent,
 			res->lr_lvb_len = rc;
 			mutex_unlock(&res->lr_lvb_mutex);
 			ldlm_resource_putref(res);
-			return NULL;
+			return ERR_PTR(rc);
 		}
 	}