btrfs: rename del_ptr to btrfs_del_ptr and export it

This exists internal to ctree.c, however btrfs check needs to use it for
some of its operations.  I'd rather not duplicate that code inside of
btrfs check as this is low level and I want to keep this code in one
place, so rename the function to btrfs_del_ptr and export it so that it
can be used inside of btrfs-progs safely.  Add a comment to make sure
this doesn't get removed by a future cleanup.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/ctree.c

@@ -37,8 +37,6 @@ static int push_node_left(struct btrfs_trans_handle *trans,
 static int balance_node_right(struct btrfs_trans_handle *trans,
 			      struct extent_buffer *dst_buf,
 			      struct extent_buffer *src_buf);
-static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
-		    int level, int slot);
 
 static const struct btrfs_csums {
 	u16		size;
@@ -1122,7 +1120,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
 		if (btrfs_header_nritems(right) == 0) {
 			btrfs_clear_buffer_dirty(trans, right);
 			btrfs_tree_unlock(right);
-			del_ptr(root, path, level + 1, pslot + 1);
+			btrfs_del_ptr(root, path, level + 1, pslot + 1);
 			root_sub_used(root, right->len);
 			btrfs_free_tree_block(trans, btrfs_root_id(root), right,
 					      0, 1);
@@ -1168,7 +1166,7 @@ static noinline int balance_level(struct btrfs_trans_handle *trans,
 	if (btrfs_header_nritems(mid) == 0) {
 		btrfs_clear_buffer_dirty(trans, mid);
 		btrfs_tree_unlock(mid);
-		del_ptr(root, path, level + 1, pslot);
+		btrfs_del_ptr(root, path, level + 1, pslot);
 		root_sub_used(root, mid->len);
 		btrfs_free_tree_block(trans, btrfs_root_id(root), mid, 0, 1);
 		free_extent_buffer_stale(mid);
@@ -4357,9 +4355,11 @@ int btrfs_duplicate_item(struct btrfs_trans_handle *trans,
  *
  * the tree should have been previously balanced so the deletion does not
  * empty a node.
+ *
+ * This is exported for use inside btrfs-progs, don't un-export it.
  */
-static void del_ptr(struct btrfs_root *root, struct btrfs_path *path,
-		    int level, int slot)
+void btrfs_del_ptr(struct btrfs_root *root, struct btrfs_path *path, int level,
+		   int slot)
 {
 	struct extent_buffer *parent = path->nodes[level];
 	u32 nritems;
@@ -4414,7 +4414,7 @@ static noinline void btrfs_del_leaf(struct btrfs_trans_handle *trans,
 				    struct extent_buffer *leaf)
 {
 	WARN_ON(btrfs_header_generation(leaf) != trans->transid);
-	del_ptr(root, path, 1, path->slots[1]);
+	btrfs_del_ptr(root, path, 1, path->slots[1]);
 
 	/*
 	 * btrfs_free_extent is expensive, we want to make sure we
@@ -4500,7 +4500,7 @@ int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 
 			/* push_leaf_left fixes the path.
 			 * make sure the path still points to our leaf
-			 * for possible call to del_ptr below
+			 * for possible call to btrfs_del_ptr below
 			 */
 			slot = path->slots[1];
 			atomic_inc(&leaf->refs);

fs/btrfs/ctree.h

@@ -541,6 +541,8 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
 		      struct extent_buffer **cow_ret, u64 new_root_objectid);
 int btrfs_block_can_be_shared(struct btrfs_root *root,
 			      struct extent_buffer *buf);
+void btrfs_del_ptr(struct btrfs_root *root, struct btrfs_path *path, int level,
+		   int slot);
 void btrfs_extend_item(struct btrfs_path *path, u32 data_size);
 void btrfs_truncate_item(struct btrfs_path *path, u32 new_size, int from_end);
 int btrfs_split_item(struct btrfs_trans_handle *trans,