[PATCH] nfsd4: slabify nfs4_files

The structures the server uses to keep track of various pieces of nfsv4 state
(open files, outstanding delegations, etc.) are likely to be allocated and
deallocated frequently and seem reasonable candidates for slab caches.

While we're at it, the slab code keeps statistics that help catch leaks and
such, so we may as well take this chance to eliminate some debugging counters
that we've been keeping ourselves.

Start with the struct nfs4_file.
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@cse.unsw.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/nfsd/nfs4state.c

@@ -70,8 +70,6 @@ u32 list_add_perfile = 0;
 u32 list_del_perfile = 0;
 u32 add_perclient = 0;
 u32 del_perclient = 0;
-u32 alloc_file = 0;
-u32 free_file = 0;
 u32 vfsopen = 0;
 u32 vfsclose = 0;
 u32 alloc_delegation= 0;
@@ -90,6 +88,9 @@ static void release_stateid_lockowners(struct nfs4_stateid *open_stp);
  */
 static DECLARE_MUTEX(client_sema);
 
+kmem_cache_t *stateowner_slab = NULL;
+kmem_cache_t *file_slab = NULL;
+
 void
 nfs4_lock_state(void)
 {
@@ -961,14 +962,14 @@ alloc_init_file(struct inode *ino)
 	struct nfs4_file *fp;
 	unsigned int hashval = file_hashval(ino);
 
-	if ((fp = kmalloc(sizeof(struct nfs4_file),GFP_KERNEL))) {
+	fp = kmem_cache_alloc(file_slab, GFP_KERNEL);
+	if (fp) {
 		INIT_LIST_HEAD(&fp->fi_hash);
 		INIT_LIST_HEAD(&fp->fi_perfile);
 		INIT_LIST_HEAD(&fp->fi_del_perfile);
 		list_add(&fp->fi_hash, &file_hashtbl[hashval]);
 		fp->fi_inode = igrab(ino);
 		fp->fi_id = current_fileid++;
-		alloc_file++;
 		return fp;
 	}
 	return NULL;
@@ -992,29 +993,41 @@ release_all_files(void)
 	}
 }
 
-kmem_cache_t *stateowner_slab = NULL;
-
-static int
-nfsd4_init_slabs(void)
+static void
+nfsd4_free_slab(kmem_cache_t **slab)
 {
-	stateowner_slab = kmem_cache_create("nfsd4_stateowners",
-			sizeof(struct nfs4_stateowner), 0, 0, NULL, NULL);
-	if (stateowner_slab == NULL) {
-		dprintk("nfsd4: out of memory while initializing nfsv4\n");
-		return -ENOMEM;
-	}
-	return 0;
+	int status;
+
+	if (*slab == NULL)
+		return;
+	status = kmem_cache_destroy(*slab);
+	*slab = NULL;
+	WARN_ON(status);
 }
 
 static void
 nfsd4_free_slabs(void)
 {
-	int status = 0;
+	nfsd4_free_slab(&stateowner_slab);
+	nfsd4_free_slab(&file_slab);
+}
 
-	if (stateowner_slab)
-		status = kmem_cache_destroy(stateowner_slab);
-	stateowner_slab = NULL;
-	BUG_ON(status);
+static int
+nfsd4_init_slabs(void)
+{
+	stateowner_slab = kmem_cache_create("nfsd4_stateowners",
+			sizeof(struct nfs4_stateowner), 0, 0, NULL, NULL);
+	if (stateowner_slab == NULL)
+		goto out_nomem;
+	file_slab = kmem_cache_create("nfsd4_files",
+			sizeof(struct nfs4_file), 0, 0, NULL, NULL);
+	if (file_slab == NULL)
+		goto out_nomem;
+	return 0;
+out_nomem:
+	nfsd4_free_slabs();
+	dprintk("nfsd4: out of memory while initializing nfsv4\n");
+	return -ENOMEM;
 }
 
 void
@@ -1167,10 +1180,9 @@ release_stateid(struct nfs4_stateid *stp, int flags)
 static void
 release_file(struct nfs4_file *fp)
 {
-	free_file++;
 	list_del(&fp->fi_hash);
 	iput(fp->fi_inode);
-	kfree(fp);
+	kmem_cache_free(file_slab, fp);
 }	
 
 void
@@ -3286,8 +3298,6 @@ __nfs4_state_shutdown(void)
 			list_add_perfile, list_del_perfile);
 	dprintk("NFSD: add_perclient %d del_perclient %d\n",
 			add_perclient, del_perclient);
-	dprintk("NFSD: alloc_file %d free_file %d\n",
-			alloc_file, free_file);
 	dprintk("NFSD: vfsopen %d vfsclose %d\n",
 			vfsopen, vfsclose);
 	dprintk("NFSD: alloc_delegation %d free_delegation %d\n",