dlm: improve rsb searches

By pre-allocating rsb structs before searching the hash
table, they can be inserted immediately.  This avoids
always having to repeat the search when adding the struct
to hash list.

This also adds space to the rsb struct for a max resource
name, so an rsb allocation can be used by any request.
The constant size also allows us to finally use a slab
for the rsb structs.

Signed-off-by: David Teigland <teigland@redhat.com>
diff --git a/fs/dlm/memory.c b/fs/dlm/memory.c
index 8e0d00d..da64df7 100644
--- a/fs/dlm/memory.c
+++ b/fs/dlm/memory.c
@@ -16,6 +16,7 @@
 #include "memory.h"
 
 static struct kmem_cache *lkb_cache;
+static struct kmem_cache *rsb_cache;
 
 
 int __init dlm_memory_init(void)
@@ -26,6 +27,14 @@
 				__alignof__(struct dlm_lkb), 0, NULL);
 	if (!lkb_cache)
 		ret = -ENOMEM;
+
+	rsb_cache = kmem_cache_create("dlm_rsb", sizeof(struct dlm_rsb),
+				__alignof__(struct dlm_rsb), 0, NULL);
+	if (!rsb_cache) {
+		kmem_cache_destroy(lkb_cache);
+		ret = -ENOMEM;
+	}
+
 	return ret;
 }
 
@@ -33,6 +42,8 @@
 {
 	if (lkb_cache)
 		kmem_cache_destroy(lkb_cache);
+	if (rsb_cache)
+		kmem_cache_destroy(rsb_cache);
 }
 
 char *dlm_allocate_lvb(struct dlm_ls *ls)
@@ -48,16 +59,11 @@
 	kfree(p);
 }
 
-/* FIXME: have some minimal space built-in to rsb for the name and
-   kmalloc a separate name if needed, like dentries are done */
-
-struct dlm_rsb *dlm_allocate_rsb(struct dlm_ls *ls, int namelen)
+struct dlm_rsb *dlm_allocate_rsb(struct dlm_ls *ls)
 {
 	struct dlm_rsb *r;
 
-	DLM_ASSERT(namelen <= DLM_RESNAME_MAXLEN,);
-
-	r = kzalloc(sizeof(*r) + namelen, GFP_NOFS);
+	r = kmem_cache_zalloc(rsb_cache, GFP_NOFS);
 	return r;
 }
 
@@ -65,7 +71,7 @@
 {
 	if (r->res_lvbptr)
 		dlm_free_lvb(r->res_lvbptr);
-	kfree(r);
+	kmem_cache_free(rsb_cache, r);
 }
 
 struct dlm_lkb *dlm_allocate_lkb(struct dlm_ls *ls)