btrfs: separate out the extent io init function

We are moving extent_io_tree into it's on file, so separate out the
extent_state init stuff from extent_io_tree_init().

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 1a17218..dffa7c6 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -200,19 +200,23 @@ static int __must_check flush_write_bio(struct extent_page_data *epd)
 	return ret;
 }
 
-int __init extent_io_init(void)
+int __init extent_state_cache_init(void)
 {
 	extent_state_cache = kmem_cache_create("btrfs_extent_state",
 			sizeof(struct extent_state), 0,
 			SLAB_MEM_SPREAD, NULL);
 	if (!extent_state_cache)
 		return -ENOMEM;
+	return 0;
+}
 
+int __init extent_io_init(void)
+{
 	extent_buffer_cache = kmem_cache_create("btrfs_extent_buffer",
 			sizeof(struct extent_buffer), 0,
 			SLAB_MEM_SPREAD, NULL);
 	if (!extent_buffer_cache)
-		goto free_state_cache;
+		return -ENOMEM;
 
 	if (bioset_init(&btrfs_bioset, BIO_POOL_SIZE,
 			offsetof(struct btrfs_io_bio, bio),
@@ -230,24 +234,24 @@ int __init extent_io_init(void)
 free_buffer_cache:
 	kmem_cache_destroy(extent_buffer_cache);
 	extent_buffer_cache = NULL;
-
-free_state_cache:
-	kmem_cache_destroy(extent_state_cache);
-	extent_state_cache = NULL;
 	return -ENOMEM;
 }
 
+void __cold extent_state_cache_exit(void)
+{
+	btrfs_extent_state_leak_debug_check();
+	kmem_cache_destroy(extent_state_cache);
+}
+
 void __cold extent_io_exit(void)
 {
 	btrfs_extent_buffer_leak_debug_check();
-	btrfs_extent_state_leak_debug_check();
 
 	/*
 	 * Make sure all delayed rcu free are flushed before we
 	 * destroy caches.
 	 */
 	rcu_barrier();
-	kmem_cache_destroy(extent_state_cache);
 	kmem_cache_destroy(extent_buffer_cache);
 	bioset_exit(&btrfs_bioset);
 }