btrfs: remove mapping tree structures indirection

fs_info::mapping_tree is the physical<->logical mapping tree and uses
the same underlying structure as extents, but is embedded to another
structure. There are no other members and this indirection is useless.
No functional change.

Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 10f7de0..a3fa741 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1818,7 +1818,7 @@ static u64 find_next_chunk(struct btrfs_fs_info *fs_info)
 	struct rb_node *n;
 	u64 ret = 0;
 
-	em_tree = &fs_info->mapping_tree.map_tree;
+	em_tree = &fs_info->mapping_tree;
 	read_lock(&em_tree->lock);
 	n = rb_last(&em_tree->map.rb_root);
 	if (n) {
@@ -2941,7 +2941,7 @@ struct extent_map *btrfs_get_chunk_map(struct btrfs_fs_info *fs_info,
 	struct extent_map_tree *em_tree;
 	struct extent_map *em;
 
-	em_tree = &fs_info->mapping_tree.map_tree;
+	em_tree = &fs_info->mapping_tree;
 	read_lock(&em_tree->lock);
 	em = lookup_extent_mapping(em_tree, logical, length);
 	read_unlock(&em_tree->lock);
@@ -5144,7 +5144,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
 	em->block_len = em->len;
 	em->orig_block_len = stripe_size;
 
-	em_tree = &info->mapping_tree.map_tree;
+	em_tree = &info->mapping_tree;
 	write_lock(&em_tree->lock);
 	ret = add_extent_mapping(em_tree, em, 0);
 	if (ret) {
@@ -5378,21 +5378,16 @@ int btrfs_chunk_readonly(struct btrfs_fs_info *fs_info, u64 chunk_offset)
 	return readonly;
 }
 
-void btrfs_mapping_init(struct btrfs_mapping_tree *tree)
-{
-	extent_map_tree_init(&tree->map_tree);
-}
-
-void btrfs_mapping_tree_free(struct btrfs_mapping_tree *tree)
+void btrfs_mapping_tree_free(struct extent_map_tree *tree)
 {
 	struct extent_map *em;
 
 	while (1) {
-		write_lock(&tree->map_tree.lock);
-		em = lookup_extent_mapping(&tree->map_tree, 0, (u64)-1);
+		write_lock(&tree->lock);
+		em = lookup_extent_mapping(tree, 0, (u64)-1);
 		if (em)
-			remove_extent_mapping(&tree->map_tree, em);
-		write_unlock(&tree->map_tree.lock);
+			remove_extent_mapping(tree, em);
+		write_unlock(&tree->lock);
 		if (!em)
 			break;
 		/* once for us */
@@ -6687,7 +6682,7 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
 			  struct btrfs_chunk *chunk)
 {
 	struct btrfs_fs_info *fs_info = leaf->fs_info;
-	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
+	struct extent_map_tree *map_tree = &fs_info->mapping_tree;
 	struct map_lookup *map;
 	struct extent_map *em;
 	u64 logical;
@@ -6712,9 +6707,9 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
 			return ret;
 	}
 
-	read_lock(&map_tree->map_tree.lock);
-	em = lookup_extent_mapping(&map_tree->map_tree, logical, 1);
-	read_unlock(&map_tree->map_tree.lock);
+	read_lock(&map_tree->lock);
+	em = lookup_extent_mapping(map_tree, logical, 1);
+	read_unlock(&map_tree->lock);
 
 	/* already mapped? */
 	if (em && em->start <= logical && em->start + em->len > logical) {
@@ -6783,9 +6778,9 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
 
 	}
 
-	write_lock(&map_tree->map_tree.lock);
-	ret = add_extent_mapping(&map_tree->map_tree, em, 0);
-	write_unlock(&map_tree->map_tree.lock);
+	write_lock(&map_tree->lock);
+	ret = add_extent_mapping(map_tree, em, 0);
+	write_unlock(&map_tree->lock);
 	if (ret < 0) {
 		btrfs_err(fs_info,
 			  "failed to add chunk map, start=%llu len=%llu: %d",
@@ -7103,14 +7098,14 @@ int btrfs_read_sys_array(struct btrfs_fs_info *fs_info)
 bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info,
 					struct btrfs_device *failing_dev)
 {
-	struct btrfs_mapping_tree *map_tree = &fs_info->mapping_tree;
+	struct extent_map_tree *map_tree = &fs_info->mapping_tree;
 	struct extent_map *em;
 	u64 next_start = 0;
 	bool ret = true;
 
-	read_lock(&map_tree->map_tree.lock);
-	em = lookup_extent_mapping(&map_tree->map_tree, 0, (u64)-1);
-	read_unlock(&map_tree->map_tree.lock);
+	read_lock(&map_tree->lock);
+	em = lookup_extent_mapping(map_tree, 0, (u64)-1);
+	read_unlock(&map_tree->lock);
 	/* No chunk at all? Return false anyway */
 	if (!em) {
 		ret = false;
@@ -7148,10 +7143,10 @@ bool btrfs_check_rw_degradable(struct btrfs_fs_info *fs_info,
 		next_start = extent_map_end(em);
 		free_extent_map(em);
 
-		read_lock(&map_tree->map_tree.lock);
-		em = lookup_extent_mapping(&map_tree->map_tree, next_start,
+		read_lock(&map_tree->lock);
+		em = lookup_extent_mapping(map_tree, next_start,
 					   (u64)(-1) - next_start);
-		read_unlock(&map_tree->map_tree.lock);
+		read_unlock(&map_tree->lock);
 	}
 out:
 	return ret;
@@ -7612,7 +7607,7 @@ static int verify_one_dev_extent(struct btrfs_fs_info *fs_info,
 				 u64 chunk_offset, u64 devid,
 				 u64 physical_offset, u64 physical_len)
 {
-	struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
+	struct extent_map_tree *em_tree = &fs_info->mapping_tree;
 	struct extent_map *em;
 	struct map_lookup *map;
 	struct btrfs_device *dev;
@@ -7701,7 +7696,7 @@ static int verify_one_dev_extent(struct btrfs_fs_info *fs_info,
 
 static int verify_chunk_dev_extent_mapping(struct btrfs_fs_info *fs_info)
 {
-	struct extent_map_tree *em_tree = &fs_info->mapping_tree.map_tree;
+	struct extent_map_tree *em_tree = &fs_info->mapping_tree;
 	struct extent_map *em;
 	struct rb_node *node;
 	int ret = 0;