Btrfs: add leaf data casting helper

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

3 files changed, 8 insertions, 9 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);
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 7f156d9b7089..3767744f659e 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -41,9 +41,7 @@ static int inc_block_ref(struct btrfs_root *root, u64 blocknr)
                 BUG();
         BUG_ON(ret != 0);
         l = &path.nodes[0]->leaf;
-        item = (struct btrfs_extent_item *)(l->data +
-                                            btrfs_item_offset(l->items +
-                                                              path.slots[0]));
+        item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
         refs = btrfs_extent_refs(item);
         btrfs_set_extent_refs(item, refs + 1);
 
@@ -69,9 +67,7 @@ static int lookup_block_ref(struct btrfs_root *root, u64 blocknr, u32 *refs)
         if (ret != 0)
                 BUG();
         l = &path.nodes[0]->leaf;
-        item = (struct btrfs_extent_item *)(l->data +
-                                      btrfs_item_offset(l->items +
-                                                        path.slots[0]));
+        item = btrfs_item_ptr(l, path.slots[0], struct btrfs_extent_item);
         *refs = btrfs_extent_refs(item);
         btrfs_release_path(root->extent_root, &path);
         return 0;
diff --git a/fs/btrfs/print-tree.c b/fs/btrfs/print-tree.c
index 64829b6b90f9..e769f36cf051 100644
--- a/fs/btrfs/print-tree.c
+++ b/fs/btrfs/print-tree.c
@@ -26,11 +26,10 @@ void btrfs_print_leaf(struct btrfs_leaf *l)
                         btrfs_item_size(item));
                 printf("\t\titem data %.*s\n", btrfs_item_size(item),
                         l->data + btrfs_item_offset(item));
-                ei = (struct btrfs_extent_item *)(l->data +
-                                                  btrfs_item_offset(item));
+                ei = btrfs_item_ptr(l, i, struct btrfs_extent_item);
                 printf("\t\textent data refs %u owner %Lu\n",
                         btrfs_extent_refs(ei), btrfs_extent_owner(ei));
-                ri = (struct btrfs_root_item *)ei;
+                ri = btrfs_item_ptr(l, i, struct btrfs_root_item);
                 printf("\t\troot data blocknr %Lu refs %u\n",
                         btrfs_root_blocknr(ri), btrfs_root_refs(ri));
                 fflush(stdout);