[PATCH 7/9] btrfs: add a btrfs_first_item helper
From: Josef Bacik <josef@toxicpanda.com>
Date: 2021-12-15 20:44:00
Subsystem:
btrfs file system, filesystems (vfs and infrastructure), the rest · Maintainers:
Chris Mason, David Sterba, Alexander Viro, Christian Brauner, Linus Torvalds
The GC tree stuff is going to use this helper and it'll make the code a bit cleaner to abstract this into a helper. Signed-off-by: Josef Bacik <josef@toxicpanda.com> --- fs/btrfs/ctree.c | 23 +++++++++++++++++++++++ fs/btrfs/ctree.h | 1 + 2 files changed, 24 insertions(+)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 781537692a4a..efb413a6db0c 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c@@ -4775,3 +4775,26 @@ int btrfs_previous_extent_item(struct btrfs_root *root, } return 1; } + +/** + * btrfs_first_item - search the given root for the first item. + * @root: the root to search. + * @path: the path to use for the search. + * @return: 0 if it found something, 1 if nothing was found and < on error. + * + * Search down and find the first item in a tree. If the root is empty return + * 1, otherwise we'll return 0 or < 0 if there was an error. + */ +int btrfs_first_item(struct btrfs_root *root, struct btrfs_path *path) +{ + struct btrfs_key key = {}; + int ret; + + ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); + if (ret > 0) { + if (btrfs_header_nritems(path->nodes[0]) == 0) + return 1; + ret = 0; + } + return ret; +}
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 2a5ed393eb21..6bcf112f9872 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h@@ -2892,6 +2892,7 @@ void btrfs_wait_for_snapshot_creation(struct btrfs_root *root); int btrfs_bin_search(struct extent_buffer *eb, const struct btrfs_key *key, int *slot); int __pure btrfs_comp_cpu_keys(const struct btrfs_key *k1, const struct btrfs_key *k2); +int btrfs_first_item(struct btrfs_root *root, struct btrfs_path *path); int btrfs_previous_item(struct btrfs_root *root, struct btrfs_path *path, u64 min_objectid, int type);
--
2.26.3