Commit 0ff40a91 authored by Marcos Paulo de Souza's avatar Marcos Paulo de Souza Committed by David Sterba
Browse files

btrfs: introduce btrfs_search_backwards function 



It's a common practice to start a search using offset (u64)-1, which is
the u64 maximum value, meaning that we want the search_slot function to
be set in the last item with the same objectid and type.

Once we are in this position, it's a matter to start a search backwards
by calling btrfs_previous_item, which will check if we'll need to go to
a previous leaf and other necessary checks, only to be sure that we are
in last offset of the same object and type.

The new btrfs_search_backwards function does the all these steps when
necessary, and can be used to avoid code duplication.

Signed-off-by: default avatarMarcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ea3dc7d2

fs/btrfs/ctree.c

+21 −0
Original line number Diff line number Diff line
@@ -2101,6 +2101,27 @@ int btrfs_search_slot_for_read(struct btrfs_root *root, 
	return 0;

}



/*

 * Execute search and call btrfs_previous_item to traverse backwards if the item

 * was not found.

 *

 * Return 0 if found, 1 if not found and < 0 if error.

 */

int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,

			   struct btrfs_path *path)

{

	int ret;



	ret = btrfs_search_slot(NULL, root, key, path, 0, 0);

	if (ret > 0)

		ret = btrfs_previous_item(root, path, key->objectid, key->type);



	if (ret == 0)

		btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]);



	return ret;

}



/*

 * adjust the pointers going up the tree, starting at level

 * making sure the right key of each node is points to 'key'.

fs/btrfs/ctree.h

+4 −0
Original line number Diff line number Diff line
@@ -2908,6 +2908,10 @@ static inline int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, 
int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path);

int btrfs_next_old_leaf(struct btrfs_root *root, struct btrfs_path *path,

			u64 time_seq);



int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key,

			   struct btrfs_path *path);



static inline int btrfs_next_old_item(struct btrfs_root *root,

				      struct btrfs_path *p, u64 time_seq)

{

fs/btrfs/ioctl.c

+8 −22
Original line number Diff line number Diff line
@@ -2389,23 +2389,16 @@ static noinline int btrfs_search_path_in_tree(struct btrfs_fs_info *info, 
	key.offset = (u64)-1;



	while (1) {

		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);

		if (ret < 0)

			goto out;

		else if (ret > 0) {

			ret = btrfs_previous_item(root, path, dirid,

						  BTRFS_INODE_REF_KEY);

		ret = btrfs_search_backwards(root, &key, path);

		if (ret < 0)

			goto out;

		else if (ret > 0) {

			ret = -ENOENT;

			goto out;

		}

		}



		l = path->nodes[0];

		slot = path->slots[0];

		btrfs_item_key_to_cpu(l, &key, slot);



		iref = btrfs_item_ptr(l, slot, struct btrfs_inode_ref);

		len = btrfs_inode_ref_name_len(l, iref);
@@ -2480,23 +2473,16 @@ static int btrfs_search_path_in_tree_user(struct inode *inode, 
		key.type = BTRFS_INODE_REF_KEY;

		key.offset = (u64)-1;

		while (1) {

			ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);

			if (ret < 0) {

				goto out_put;

			} else if (ret > 0) {

				ret = btrfs_previous_item(root, path, dirid,

							  BTRFS_INODE_REF_KEY);

				if (ret < 0) {

			ret = btrfs_search_backwards(root, &key, path);

			if (ret < 0)

				goto out_put;

				} else if (ret > 0) {

			else if (ret > 0) {

				ret = -ENOENT;

				goto out_put;

			}

			}



			leaf = path->nodes[0];

			slot = path->slots[0];

			btrfs_item_key_to_cpu(leaf, &key, slot);



			iref = btrfs_item_ptr(leaf, slot, struct btrfs_inode_ref);

			len = btrfs_inode_ref_name_len(leaf, iref);

fs/btrfs/super.c

+6 −20
Original line number Diff line number Diff line
@@ -1201,21 +1201,14 @@ char *btrfs_get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, 
		key.type = BTRFS_ROOT_BACKREF_KEY;

		key.offset = (u64)-1;



		ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);

		if (ret < 0) {

			goto err;

		} else if (ret > 0) {

			ret = btrfs_previous_item(root, path, subvol_objectid,

						  BTRFS_ROOT_BACKREF_KEY);

		ret = btrfs_search_backwards(root, &key, path);

		if (ret < 0) {

			goto err;

		} else if (ret > 0) {

			ret = -ENOENT;

			goto err;

		}

		}



		btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);

		subvol_objectid = key.offset;



		root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
@@ -1248,21 +1241,14 @@ char *btrfs_get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info, 
			key.type = BTRFS_INODE_REF_KEY;

			key.offset = (u64)-1;



			ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);

			if (ret < 0) {

				goto err;

			} else if (ret > 0) {

				ret = btrfs_previous_item(fs_root, path, dirid,

							  BTRFS_INODE_REF_KEY);

			ret = btrfs_search_backwards(fs_root, &key, path);

			if (ret < 0) {

				goto err;

			} else if (ret > 0) {

				ret = -ENOENT;

				goto err;

			}

			}



			btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);

			dirid = key.offset;



			inode_ref = btrfs_item_ptr(path->nodes[0],

fs/btrfs/volumes.c

+1 −6
Original line number Diff line number Diff line
@@ -1586,14 +1586,9 @@ static int find_free_dev_extent_start(struct btrfs_device *device, 
	key.offset = search_start;

	key.type = BTRFS_DEV_EXTENT_KEY;



	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);

	ret = btrfs_search_backwards(root, &key, path);

	if (ret < 0)

		goto out;

	if (ret > 0) {

		ret = btrfs_previous_item(root, path, key.objectid, key.type);

		if (ret < 0)

			goto out;

	}



	while (1) {

		l = path->nodes[0];