btrfs-progs: map-logical: introduce map_one_extent function

Introduce the function to get accurate extent length based on extent
tree search.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

diff --git a/btrfs-map-logical.c b/btrfs-map-logical.c
index e5e2da5..8442779 100644 (file)
--- a/btrfs-map-logical.c
+++ b/btrfs-map-logical.c
@@ -35,6 +35,64 @@
  * */
 static FILE *info_file;
 
+static int map_one_extent(struct btrfs_fs_info *fs_info,
+                         u64 *logical_ret, u64 *len_ret, int search_foward)
+{
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       u64 logical;
+       u64 len = 0;
+       int ret = 0;
+
+       BUG_ON(!logical_ret);
+       logical = *logical_ret;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = logical;
+       key.type = 0;
+       key.offset = 0;
+
+       ret = btrfs_search_slot(NULL, fs_info->extent_root, &key, path,
+                               0, 0);
+       if (ret < 0)
+               goto out;
+       BUG_ON(ret == 0);
+       ret = 0;
+
+again:
+       btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+       if ((search_foward && key.objectid < logical) ||
+           (!search_foward && key.objectid > logical) ||
+           (key.type != BTRFS_EXTENT_ITEM_KEY &&
+            key.type != BTRFS_METADATA_ITEM_KEY)) {
+               if (!search_foward)
+                       ret = btrfs_previous_extent_item(fs_info->extent_root,
+                                                        path, 0);
+               else
+                       ret = btrfs_next_item(fs_info->extent_root, path);
+               if (ret)
+                       goto out;
+               goto again;
+       }
+       logical = key.objectid;
+       if (key.type == BTRFS_METADATA_ITEM_KEY)
+               len = fs_info->tree_root->leafsize;
+       else
+               len = key.offset;
+
+out:
+       btrfs_free_path(path);
+       if (!ret) {
+               *logical_ret = logical;
+               if (len_ret)
+                       *len_ret = len;
+       }
+       return ret;
+}
+
 static struct extent_buffer * debug_read_block(struct btrfs_root *root,
                u64 bytenr, u32 blocksize, u64 copy)
 {