Btrfs: add leaf data casting helper

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0968899fb7f9..05c7707263f5 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -401,6 +401,10 @@ static inline void btrfs_set_super_blocksize(struct btrfs_super_block *s,
         s->blocksize = cpu_to_le16(val);
 }
 
+/* helper function to cast into the data area of the leaf. */
+#define btrfs_item_ptr(leaf, slot, type) \
+        ((type *)((leaf)->data + btrfs_item_offset((leaf)->items + (slot))))
+
 struct btrfs_buffer *btrfs_alloc_free_block(struct btrfs_root *root);
 int btrfs_inc_ref(struct btrfs_root *root, struct btrfs_buffer *buf);
 int btrfs_free_extent(struct btrfs_root *root, u64 blocknr, u64 num_blocks);