btrfs: pass the root owner and level around for readahead

The readahead infrastructure does raw reads of extent buffers, but we're
going to need to know their owner and level in order to set the lockdep
key properly, so plumb in the infrastructure that we'll need to have
this information when we start allocating extent buffers.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/reada.c

@@ -52,6 +52,7 @@ struct reada_extctl {
 
 struct reada_extent {
 	u64			logical;
+	u64			owner_root;
 	struct btrfs_key	top;
 	struct list_head	extctl;
 	int 			refcnt;
@@ -59,6 +60,7 @@ struct reada_extent {
 	struct reada_zone	*zones[BTRFS_MAX_MIRRORS];
 	int			nzones;
 	int			scheduled;
+	int			level;
 };
 
 struct reada_zone {
@@ -87,7 +89,8 @@ static void reada_start_machine(struct btrfs_fs_info *fs_info);
 static void __reada_start_machine(struct btrfs_fs_info *fs_info);
 
 static int reada_add_block(struct reada_control *rc, u64 logical,
-			   struct btrfs_key *top, u64 generation);
+			   struct btrfs_key *top, u64 owner_root,
+			   u64 generation, int level);
 
 /* recurses */
 /* in case of err, eb might be NULL */
@@ -165,7 +168,9 @@ static void __readahead_hook(struct btrfs_fs_info *fs_info,
 			if (rec->generation == generation &&
 			    btrfs_comp_cpu_keys(&key, &rc->key_end) < 0 &&
 			    btrfs_comp_cpu_keys(&next_key, &rc->key_start) > 0)
-				reada_add_block(rc, bytenr, &next_key, n_gen);
+				reada_add_block(rc, bytenr, &next_key,
+						btrfs_header_owner(eb), n_gen,
+						btrfs_header_level(eb) - 1);
 		}
 	}
 
@@ -298,7 +303,8 @@ static struct reada_zone *reada_find_zone(struct btrfs_device *dev, u64 logical,
 
 static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 					      u64 logical,
-					      struct btrfs_key *top)
+					      struct btrfs_key *top,
+					      u64 owner_root, int level)
 {
 	int ret;
 	struct reada_extent *re = NULL;
@@ -331,6 +337,8 @@ static struct reada_extent *reada_find_extent(struct btrfs_fs_info *fs_info,
 	INIT_LIST_HEAD(&re->extctl);
 	spin_lock_init(&re->lock);
 	re->refcnt = 1;
+	re->owner_root = owner_root;
+	re->level = level;
 
 	/*
 	 * map block
@@ -548,14 +556,15 @@ static void reada_control_release(struct kref *kref)
 }
 
 static int reada_add_block(struct reada_control *rc, u64 logical,
-			   struct btrfs_key *top, u64 generation)
+			   struct btrfs_key *top, u64 owner_root,
+			   u64 generation, int level)
 {
 	struct btrfs_fs_info *fs_info = rc->fs_info;
 	struct reada_extent *re;
 	struct reada_extctl *rec;
 
 	/* takes one ref */
-	re = reada_find_extent(fs_info, logical, top);
+	re = reada_find_extent(fs_info, logical, top, owner_root, level);
 	if (!re)
 		return -1;
 
@@ -947,6 +956,7 @@ struct reada_control *btrfs_reada_add(struct btrfs_root *root,
 	u64 start;
 	u64 generation;
 	int ret;
+	int level;
 	struct extent_buffer *node;
 	static struct btrfs_key max_key = {
 		.objectid = (u64)-1,
@@ -969,9 +979,11 @@ struct reada_control *btrfs_reada_add(struct btrfs_root *root,
 	node = btrfs_root_node(root);
 	start = node->start;
 	generation = btrfs_header_generation(node);
+	level = btrfs_header_level(node);
 	free_extent_buffer(node);
 
-	ret = reada_add_block(rc, start, &max_key, generation);
+	ret = reada_add_block(rc, start, &max_key, root->root_key.objectid,
+			      generation, level);
 	if (ret) {
 		kfree(rc);
 		return ERR_PTR(ret);