btrfs: use slab for end_io_wq structures

The structure is frequently reused.  Rename it according to the slab
name.
Signed-off-by: David Sterba <dsterba@suse.cz>

fs/btrfs/disk-io.c

@@ -72,11 +72,11 @@ static int btrfs_cleanup_transaction(struct btrfs_root *root);
 static void btrfs_error_commit_super(struct btrfs_root *root);
 
 /*
- * end_io_wq structs are used to do processing in task context when an IO is
- * complete.  This is used during reads to verify checksums, and it is used
+ * btrfs_end_io_wq structs are used to do processing in task context when an IO
+ * is complete.  This is used during reads to verify checksums, and it is used
  * by writes to insert metadata for new file extents after IO is complete.
  */
-struct end_io_wq {
+struct btrfs_end_io_wq {
 	struct bio *bio;
 	bio_end_io_t *end_io;
 	void *private;
@@ -87,6 +87,26 @@ struct end_io_wq {
 	struct btrfs_work work;
 };
 
+static struct kmem_cache *btrfs_end_io_wq_cache;
+
+int __init btrfs_end_io_wq_init(void)
+{
+	btrfs_end_io_wq_cache = kmem_cache_create("btrfs_end_io_wq",
+					sizeof(struct btrfs_end_io_wq),
+					0,
+					SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD,
+					NULL);
+	if (!btrfs_end_io_wq_cache)
+		return -ENOMEM;
+	return 0;
+}
+
+void btrfs_end_io_wq_exit(void)
+{
+	if (btrfs_end_io_wq_cache)
+		kmem_cache_destroy(btrfs_end_io_wq_cache);
+}
+
 /*
  * async submit bios are used to offload expensive checksumming
  * onto the worker threads.  They checksum file and metadata bios
@@ -690,7 +710,7 @@ static int btree_io_failed_hook(struct page *page, int failed_mirror)
 
 static void end_workqueue_bio(struct bio *bio, int err)
 {
-	struct end_io_wq *end_io_wq = bio->bi_private;
+	struct btrfs_end_io_wq *end_io_wq = bio->bi_private;
 	struct btrfs_fs_info *fs_info;
 	struct btrfs_workqueue *wq;
 	btrfs_work_func_t func;
@@ -736,9 +756,9 @@ static void end_workqueue_bio(struct bio *bio, int err)
 int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
 			enum btrfs_wq_endio_type metadata)
 {
-	struct end_io_wq *end_io_wq;
+	struct btrfs_end_io_wq *end_io_wq;
 
-	end_io_wq = kmalloc(sizeof(*end_io_wq), GFP_NOFS);
+	end_io_wq = kmem_cache_alloc(btrfs_end_io_wq_cache, GFP_NOFS);
 	if (!end_io_wq)
 		return -ENOMEM;
 
@@ -1723,16 +1743,16 @@ static int setup_bdi(struct btrfs_fs_info *info, struct backing_dev_info *bdi)
 static void end_workqueue_fn(struct btrfs_work *work)
 {
 	struct bio *bio;
-	struct end_io_wq *end_io_wq;
+	struct btrfs_end_io_wq *end_io_wq;
 	int error;
 
-	end_io_wq = container_of(work, struct end_io_wq, work);
+	end_io_wq = container_of(work, struct btrfs_end_io_wq, work);
 	bio = end_io_wq->bio;
 
 	error = end_io_wq->error;
 	bio->bi_private = end_io_wq->private;
 	bio->bi_end_io = end_io_wq->end_io;
-	kfree(end_io_wq);
+	kmem_cache_free(btrfs_end_io_wq_cache, end_io_wq);
 	bio_endio_nodec(bio, error);
 }
 

fs/btrfs/disk-io.h

@@ -142,6 +142,8 @@ int btree_lock_page_hook(struct page *page, void *data,
 				void (*flush_fn)(void *));
 int btrfs_calc_num_tolerated_disk_barrier_failures(
 	struct btrfs_fs_info *fs_info);
+int __init btrfs_end_io_wq_init(void);
+void btrfs_end_io_wq_exit(void);
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 void btrfs_init_lockdep(void);

fs/btrfs/super.c

@@ -2001,10 +2001,14 @@ static int __init init_btrfs_fs(void)
 	if (err)
 		goto free_delayed_ref;
 
-	err = btrfs_interface_init();
+	err = btrfs_end_io_wq_init();
 	if (err)
 		goto free_prelim_ref;
 
+	err = btrfs_interface_init();
+	if (err)
+		goto free_end_io_wq;
+
 	btrfs_init_lockdep();
 
 	btrfs_print_info();
@@ -2021,6 +2025,8 @@ static int __init init_btrfs_fs(void)
 
 unregister_ioctl:
 	btrfs_interface_exit();
+free_end_io_wq:
+	btrfs_end_io_wq_exit();
 free_prelim_ref:
 	btrfs_prelim_ref_exit();
 free_delayed_ref: