btrfs: simplify root lookup by id

The main function to lookup a root by its id btrfs_get_fs_root takes the
whole key, while only using the objectid. The value of offset is preset
to (u64)-1 but not actually used until btrfs_find_root that does the
actual search.

Switch btrfs_get_fs_root to use only objectid and remove all local
variables that existed just for the lookup. The actual key for search is
set up in btrfs_get_fs_root, reusing another key variable.
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/backref.c

@@ -538,18 +538,13 @@ static int resolve_indirect_ref(struct btrfs_fs_info *fs_info,
 				const u64 *extent_item_pos, bool ignore_offset)
 {
 	struct btrfs_root *root;
-	struct btrfs_key root_key;
 	struct extent_buffer *eb;
 	int ret = 0;
 	int root_level;
 	int level = ref->level;
 	struct btrfs_key search_key = ref->key_for_search;
 
-	root_key.objectid = ref->root_id;
-	root_key.type = BTRFS_ROOT_ITEM_KEY;
-	root_key.offset = (u64)-1;
-
-	root = btrfs_get_fs_root(fs_info, &root_key, false);
+	root = btrfs_get_fs_root(fs_info, ref->root_id, false);
 	if (IS_ERR(root)) {
 		ret = PTR_ERR(root);
 		goto out_free;
@@ -2690,16 +2685,12 @@ static int handle_indirect_tree_backref(struct btrfs_backref_cache *cache,
 	struct btrfs_backref_edge *edge;
 	struct extent_buffer *eb;
 	struct btrfs_root *root;
-	struct btrfs_key root_key;
 	struct rb_node *rb_node;
 	int level;
 	bool need_check = true;
 	int ret;
 
-	root_key.objectid = ref_key->offset;
-	root_key.type = BTRFS_ROOT_ITEM_KEY;
-	root_key.offset = (u64)-1;
-	root = btrfs_get_fs_root(fs_info, &root_key, false);
+	root = btrfs_get_fs_root(fs_info, ref_key->offset, false);
 	if (IS_ERR(root))
 		return PTR_ERR(root);
 	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))

fs/btrfs/disk-io.c

@@ -1534,35 +1534,34 @@ void btrfs_free_fs_info(struct btrfs_fs_info *fs_info)
 
 
 struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info,
-				     struct btrfs_key *location,
-				     bool check_ref)
+				     u64 objectid, bool check_ref)
 {
 	struct btrfs_root *root;
 	struct btrfs_path *path;
 	struct btrfs_key key;
 	int ret;
 
-	if (location->objectid == BTRFS_ROOT_TREE_OBJECTID)
+	if (objectid == BTRFS_ROOT_TREE_OBJECTID)
 		return btrfs_grab_root(fs_info->tree_root);
-	if (location->objectid == BTRFS_EXTENT_TREE_OBJECTID)
+	if (objectid == BTRFS_EXTENT_TREE_OBJECTID)
 		return btrfs_grab_root(fs_info->extent_root);
-	if (location->objectid == BTRFS_CHUNK_TREE_OBJECTID)
+	if (objectid == BTRFS_CHUNK_TREE_OBJECTID)
 		return btrfs_grab_root(fs_info->chunk_root);
-	if (location->objectid == BTRFS_DEV_TREE_OBJECTID)
+	if (objectid == BTRFS_DEV_TREE_OBJECTID)
 		return btrfs_grab_root(fs_info->dev_root);
-	if (location->objectid == BTRFS_CSUM_TREE_OBJECTID)
+	if (objectid == BTRFS_CSUM_TREE_OBJECTID)
 		return btrfs_grab_root(fs_info->csum_root);
-	if (location->objectid == BTRFS_QUOTA_TREE_OBJECTID)
+	if (objectid == BTRFS_QUOTA_TREE_OBJECTID)
 		return btrfs_grab_root(fs_info->quota_root) ?
 			fs_info->quota_root : ERR_PTR(-ENOENT);
-	if (location->objectid == BTRFS_UUID_TREE_OBJECTID)
+	if (objectid == BTRFS_UUID_TREE_OBJECTID)
 		return btrfs_grab_root(fs_info->uuid_root) ?
 			fs_info->uuid_root : ERR_PTR(-ENOENT);
-	if (location->objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
+	if (objectid == BTRFS_FREE_SPACE_TREE_OBJECTID)
 		return btrfs_grab_root(fs_info->free_space_root) ?
 			fs_info->free_space_root : ERR_PTR(-ENOENT);
 again:
-	root = btrfs_lookup_fs_root(fs_info, location->objectid);
+	root = btrfs_lookup_fs_root(fs_info, objectid);
 	if (root) {
 		if (check_ref && btrfs_root_refs(&root->root_item) == 0) {
 			btrfs_put_root(root);
@@ -1571,7 +1570,10 @@ struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info,
 		return root;
 	}
 
-	root = btrfs_read_tree_root(fs_info->tree_root, location);
+	key.objectid = objectid;
+	key.type = BTRFS_ROOT_ITEM_KEY;
+	key.offset = (u64)-1;
+	root = btrfs_read_tree_root(fs_info->tree_root, &key);
 	if (IS_ERR(root))
 		return root;
 
@@ -1591,7 +1593,7 @@ struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info,
 	}
 	key.objectid = BTRFS_ORPHAN_OBJECTID;
 	key.type = BTRFS_ORPHAN_ITEM_KEY;
-	key.offset = location->objectid;
+	key.offset = objectid;
 
 	ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
 	btrfs_free_path(path);
@@ -2293,8 +2295,8 @@ static int btrfs_read_roots(struct btrfs_fs_info *fs_info)
 	 * This tree can share blocks with some other fs tree during relocation
 	 * and we need a proper setup by btrfs_get_fs_root
 	 */
-	location.objectid = BTRFS_DATA_RELOC_TREE_OBJECTID;
-	root = btrfs_get_fs_root(tree_root->fs_info, &location, true);
+	root = btrfs_get_fs_root(tree_root->fs_info,
+				 BTRFS_DATA_RELOC_TREE_OBJECTID, true);
 	if (IS_ERR(root)) {
 		ret = PTR_ERR(root);
 		goto out;
@@ -2839,7 +2841,6 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 	u64 generation;
 	u64 features;
 	u16 csum_type;
-	struct btrfs_key location;
 	struct btrfs_super_block *disk_super;
 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
 	struct btrfs_root *tree_root;
@@ -3253,11 +3254,7 @@ int __cold open_ctree(struct super_block *sb, struct btrfs_fs_devices *fs_device
 		}
 	}
 
-	location.objectid = BTRFS_FS_TREE_OBJECTID;
-	location.type = BTRFS_ROOT_ITEM_KEY;
-	location.offset = 0;
-
-	fs_info->fs_root = btrfs_get_fs_root(fs_info, &location, true);
+	fs_info->fs_root = btrfs_get_fs_root(fs_info, BTRFS_FS_TREE_OBJECTID, true);
 	if (IS_ERR(fs_info->fs_root)) {
 		err = PTR_ERR(fs_info->fs_root);
 		btrfs_warn(fs_info, "failed to read fs tree: %d", err);

fs/btrfs/disk-io.h

@@ -66,8 +66,7 @@ int btrfs_insert_fs_root(struct btrfs_fs_info *fs_info,
 void btrfs_free_fs_roots(struct btrfs_fs_info *fs_info);
 
 struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info,
-				     struct btrfs_key *key,
-				     bool check_ref);
+				     u64 objectid, bool check_ref);
 
 void btrfs_free_fs_info(struct btrfs_fs_info *fs_info);
 int btrfs_cleanup_fs_roots(struct btrfs_fs_info *fs_info);

fs/btrfs/export.c

@@ -69,11 +69,7 @@ struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
 	if (objectid < BTRFS_FIRST_FREE_OBJECTID)
 		return ERR_PTR(-ESTALE);
 
-	key.objectid = root_objectid;
-	key.type = BTRFS_ROOT_ITEM_KEY;
-	key.offset = (u64)-1;
-
-	root = btrfs_get_fs_root(fs_info, &key, true);
+	root = btrfs_get_fs_root(fs_info, root_objectid, true);
 	if (IS_ERR(root))
 		return ERR_CAST(root);
 

fs/btrfs/file.c

@@ -281,11 +281,7 @@ static int __btrfs_run_defrag_inode(struct btrfs_fs_info *fs_info,
 	int ret;
 
 	/* get the inode */
-	key.objectid = defrag->root;
-	key.type = BTRFS_ROOT_ITEM_KEY;
-	key.offset = (u64)-1;
-
-	inode_root = btrfs_get_fs_root(fs_info, &key, true);
+	inode_root = btrfs_get_fs_root(fs_info, defrag->root, true);
 	if (IS_ERR(inode_root)) {
 		ret = PTR_ERR(inode_root);
 		goto cleanup;

fs/btrfs/inode.c

@@ -5145,7 +5145,7 @@ static int fixup_tree_root_location(struct btrfs_fs_info *fs_info,
 
 	btrfs_release_path(path);
 
-	new_root = btrfs_get_fs_root(fs_info, location, true);
+	new_root = btrfs_get_fs_root(fs_info, location->objectid, true);
 	if (IS_ERR(new_root)) {
 		err = PTR_ERR(new_root);
 		goto out;

fs/btrfs/ioctl.c

@@ -660,7 +660,7 @@ static noinline int create_subvol(struct inode *dir,
 		goto fail;
 
 	key.offset = (u64)-1;
-	new_root = btrfs_get_fs_root(fs_info, &key, true);
+	new_root = btrfs_get_fs_root(fs_info, objectid, true);
 	if (IS_ERR(new_root)) {
 		ret = PTR_ERR(new_root);
 		btrfs_abort_transaction(trans, ret);
@@ -2139,10 +2139,7 @@ static noinline int search_ioctl(struct inode *inode,
 		/* search the root of the inode that was passed */
 		root = btrfs_grab_root(BTRFS_I(inode)->root);
 	} else {
-		key.objectid = sk->tree_id;
-		key.type = BTRFS_ROOT_ITEM_KEY;
-		key.offset = (u64)-1;
-		root = btrfs_get_fs_root(info, &key, true);
+		root = btrfs_get_fs_root(info, sk->tree_id, true);
 		if (IS_ERR(root)) {
 			btrfs_free_path(path);
 			return PTR_ERR(root);
@@ -2275,10 +2272,7 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info,
 
 	ptr = &name[BTRFS_INO_LOOKUP_PATH_MAX - 1];
 
-	key.objectid = tree_id;
-	key.type = BTRFS_ROOT_ITEM_KEY;
-	key.offset = (u64)-1;
-	root = btrfs_get_fs_root(info, &key, true);
+	root = btrfs_get_fs_root(info, tree_id, true);
 	if (IS_ERR(root)) {
 		ret = PTR_ERR(root);
 		root = NULL;
@@ -2371,10 +2365,7 @@ static int btrfs_search_path_in_tree_user(struct inode *inode,
 	if (dirid != upper_limit.objectid) {
 		ptr = &args->path[BTRFS_INO_LOOKUP_USER_PATH_MAX - 1];
 
-		key.objectid = treeid;
-		key.type = BTRFS_ROOT_ITEM_KEY;
-		key.offset = (u64)-1;
-		root = btrfs_get_fs_root(fs_info, &key, true);
+		root = btrfs_get_fs_root(fs_info, treeid, true);
 		if (IS_ERR(root)) {
 			ret = PTR_ERR(root);
 			goto out;
@@ -2620,9 +2611,7 @@ static int btrfs_ioctl_get_subvol_info(struct file *file, void __user *argp)
 
 	/* Get root_item of inode's subvolume */
 	key.objectid = BTRFS_I(inode)->root->root_key.objectid;
-	key.type = BTRFS_ROOT_ITEM_KEY;
-	key.offset = (u64)-1;
-	root = btrfs_get_fs_root(fs_info, &key, true);
+	root = btrfs_get_fs_root(fs_info, key.objectid, true);
 	if (IS_ERR(root)) {
 		ret = PTR_ERR(root);
 		goto out_free;
@@ -3290,7 +3279,6 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
 	struct btrfs_dir_item *di;
 	struct btrfs_trans_handle *trans;
 	struct btrfs_path *path = NULL;
-	struct btrfs_key location;
 	struct btrfs_disk_key disk_key;
 	u64 objectid = 0;
 	u64 dir_id;
@@ -3311,11 +3299,7 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp)
 	if (!objectid)
 		objectid = BTRFS_FS_TREE_OBJECTID;
 
-	location.objectid = objectid;
-	location.type = BTRFS_ROOT_ITEM_KEY;
-	location.offset = (u64)-1;
-
-	new_root = btrfs_get_fs_root(fs_info, &location, true);
+	new_root = btrfs_get_fs_root(fs_info, objectid, true);
 	if (IS_ERR(new_root)) {
 		ret = PTR_ERR(new_root);
 		goto out;

fs/btrfs/relocation.c

@@ -368,13 +368,7 @@ struct btrfs_root *find_reloc_root(struct btrfs_fs_info *fs_info, u64 bytenr)
 static struct btrfs_root *read_fs_root(struct btrfs_fs_info *fs_info,
 					u64 root_objectid)
 {
-	struct btrfs_key key;
-
-	key.objectid = root_objectid;
-	key.type = BTRFS_ROOT_ITEM_KEY;
-	key.offset = (u64)-1;
-
-	return btrfs_get_fs_root(fs_info, &key, false);
+	return btrfs_get_fs_root(fs_info, root_objectid, false);
 }
 
 /*

fs/btrfs/root-tree.c

@@ -210,7 +210,6 @@ int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
 	struct extent_buffer *leaf;
 	struct btrfs_path *path;
 	struct btrfs_key key;
-	struct btrfs_key root_key;
 	struct btrfs_root *root;
 	int err = 0;
 	int ret;
@@ -223,10 +222,9 @@ int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
 	key.type = BTRFS_ORPHAN_ITEM_KEY;
 	key.offset = 0;
 
-	root_key.type = BTRFS_ROOT_ITEM_KEY;
-	root_key.offset = (u64)-1;
-
 	while (1) {
+		u64 root_objectid;
+
 		ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 		if (ret < 0) {
 			err = ret;
@@ -250,10 +248,10 @@ int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
 		    key.type != BTRFS_ORPHAN_ITEM_KEY)
 			break;
 
-		root_key.objectid = key.offset;
+		root_objectid = key.offset;
 		key.offset++;
 
-		root = btrfs_get_fs_root(fs_info, &root_key, false);
+		root = btrfs_get_fs_root(fs_info, root_objectid, false);
 		err = PTR_ERR_OR_ZERO(root);
 		if (err && err != -ENOENT) {
 			break;
@@ -270,7 +268,7 @@ int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
 				break;
 			}
 			err = btrfs_del_orphan_item(trans, tree_root,
-						    root_key.objectid);
+						    root_objectid);
 			btrfs_end_transaction(trans);
 			if (err) {
 				btrfs_handle_fs_error(fs_info, err,

fs/btrfs/scrub.c

@@ -647,13 +647,9 @@ static int scrub_print_warning_inode(u64 inum, u64 offset, u64 root,
 	struct btrfs_fs_info *fs_info = swarn->dev->fs_info;
 	struct inode_fs_paths *ipath = NULL;
 	struct btrfs_root *local_root;
-	struct btrfs_key root_key;
 	struct btrfs_key key;
 
-	root_key.objectid = root;
-	root_key.type = BTRFS_ROOT_ITEM_KEY;
-	root_key.offset = (u64)-1;
-	local_root = btrfs_get_fs_root(fs_info, &root_key, true);
+	local_root = btrfs_get_fs_root(fs_info, root, true);
 	if (IS_ERR(local_root)) {
 		ret = PTR_ERR(local_root);
 		goto err;

fs/btrfs/send.c

@@ -7088,7 +7088,6 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
 	struct btrfs_root *send_root = BTRFS_I(file_inode(mnt_file))->root;
 	struct btrfs_fs_info *fs_info = send_root->fs_info;
 	struct btrfs_root *clone_root;
-	struct btrfs_key key;
 	struct send_ctx *sctx = NULL;
 	u32 i;
 	u64 *clone_sources_tmp = NULL;
@@ -7217,11 +7216,8 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
 		}
 
 		for (i = 0; i < arg->clone_sources_count; i++) {
-			key.objectid = clone_sources_tmp[i];
-			key.type = BTRFS_ROOT_ITEM_KEY;
-			key.offset = (u64)-1;
-
-			clone_root = btrfs_get_fs_root(fs_info, &key, true);
+			clone_root = btrfs_get_fs_root(fs_info,
+						clone_sources_tmp[i], true);
 			if (IS_ERR(clone_root)) {
 				ret = PTR_ERR(clone_root);
 				goto out;
@@ -7252,11 +7248,8 @@ long btrfs_ioctl_send(struct file *mnt_file, struct btrfs_ioctl_send_args *arg)
 	}
 
 	if (arg->parent_root) {
-		key.objectid = arg->parent_root;
-		key.type = BTRFS_ROOT_ITEM_KEY;
-		key.offset = (u64)-1;
-
-		sctx->parent_root = btrfs_get_fs_root(fs_info, &key, true);
+		sctx->parent_root = btrfs_get_fs_root(fs_info, arg->parent_root,
+						      true);
 		if (IS_ERR(sctx->parent_root)) {
 			ret = PTR_ERR(sctx->parent_root);
 			goto out;

fs/btrfs/super.c

@@ -1102,10 +1102,7 @@ char *btrfs_get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
 		dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
 		btrfs_release_path(path);
 
-		key.objectid = subvol_objectid;
-		key.type = BTRFS_ROOT_ITEM_KEY;
-		key.offset = (u64)-1;
-		fs_root = btrfs_get_fs_root(fs_info, &key, true);
+		fs_root = btrfs_get_fs_root(fs_info, subvol_objectid, true);
 		if (IS_ERR(fs_root)) {
 			ret = PTR_ERR(fs_root);
 			fs_root = NULL;

fs/btrfs/transaction.c

@@ -1630,7 +1630,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 	}
 
 	key.offset = (u64)-1;
-	pending->snap = btrfs_get_fs_root(fs_info, &key, true);
+	pending->snap = btrfs_get_fs_root(fs_info, objectid, true);
 	if (IS_ERR(pending->snap)) {
 		ret = PTR_ERR(pending->snap);
 		btrfs_abort_transaction(trans, ret);

fs/btrfs/tree-log.c

@@ -6112,7 +6112,6 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 	struct btrfs_trans_handle *trans;
 	struct btrfs_key key;
 	struct btrfs_key found_key;
-	struct btrfs_key tmp_key;
 	struct btrfs_root *log;
 	struct btrfs_fs_info *fs_info = log_root_tree->fs_info;
 	struct walk_control wc = {
@@ -6174,11 +6173,8 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 			goto error;
 		}
 
-		tmp_key.objectid = found_key.offset;
-		tmp_key.type = BTRFS_ROOT_ITEM_KEY;
-		tmp_key.offset = (u64)-1;
-
-		wc.replay_dest = btrfs_get_fs_root(fs_info, &tmp_key, true);
+		wc.replay_dest = btrfs_get_fs_root(fs_info, found_key.offset,
+						   true);
 		if (IS_ERR(wc.replay_dest)) {
 			ret = PTR_ERR(wc.replay_dest);
 

fs/btrfs/uuid-tree.c

@@ -257,7 +257,6 @@ static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
 static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
 				       u8 *uuid, u8 type, u64 subvolid)
 {
-	struct btrfs_key key;
 	int ret = 0;
 	struct btrfs_root *subvol_root;
 
@@ -265,10 +264,7 @@ static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
 	    type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
 		goto out;
 
-	key.objectid = subvolid;
-	key.type = BTRFS_ROOT_ITEM_KEY;
-	key.offset = (u64)-1;
-	subvol_root = btrfs_get_fs_root(fs_info, &key, true);
+	subvol_root = btrfs_get_fs_root(fs_info, subvolid, true);
 	if (IS_ERR(subvol_root)) {
 		ret = PTR_ERR(subvol_root);
 		if (ret == -ENOENT)