1 files changed, 16 insertions, 0 deletions

diff --git a/fs/btrfs/struct-funcs.c b/fs/btrfs/struct-funcs.c
index cf68fcf9b552..c5715a60554c 100644
--- a/fs/btrfs/struct-funcs.c
+++ b/fs/btrfs/struct-funcs.c
@@ -95,3 +95,19 @@ void btrfs_set_##name(struct extent_buffer *eb,				\
 
 #include "ctree.h"
 
+void btrfs_node_key(struct extent_buffer *eb,
+                    struct btrfs_disk_key *disk_key, int nr)
+{
+        unsigned long ptr = btrfs_node_key_ptr_offset(nr);
+        if (eb->map_token && ptr >= eb->map_start &&
+            ptr + sizeof(*disk_key) <= eb->map_start + eb->map_len) {
+                memcpy(disk_key, eb->kaddr + ptr - eb->map_start,
+                        sizeof(*disk_key));
+                return;
+        } else if (eb->map_token) {
+                unmap_extent_buffer(eb, eb->map_token, KM_USER1);
+                eb->map_token = NULL;
+        }
+        read_eb_member(eb, (struct btrfs_key_ptr *)ptr,
+                       struct btrfs_key_ptr, key, disk_key);
+}