btrfs: Remove extent_io_ops::clear_bit_hook callback

This is the counterpart to ex-set_bit_hook (now btrfs_set_delalloc_extent),
similar to what was done before remove clear_bit_hook and rename the
function. No functional changes.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 1678ada..b9aadbf 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -404,13 +404,6 @@ static void merge_state(struct extent_io_tree *tree,
 	}
 }
 
-static void clear_state_cb(struct extent_io_tree *tree,
-			   struct extent_state *state, unsigned *bits)
-{
-	if (tree->ops && tree->ops->clear_bit_hook)
-		tree->ops->clear_bit_hook(tree->private_data, state, bits);
-}
-
 static void set_state_bits(struct extent_io_tree *tree,
 			   struct extent_state *state, unsigned *bits,
 			   struct extent_changeset *changeset);
@@ -525,7 +518,10 @@ static struct extent_state *clear_state_bit(struct extent_io_tree *tree,
 		WARN_ON(range > tree->dirty_bytes);
 		tree->dirty_bytes -= range;
 	}
-	clear_state_cb(tree, state, bits);
+
+	if (tree->private_data && is_data_inode(tree->private_data))
+		btrfs_clear_delalloc_extent(tree->private_data, state, bits);
+
 	ret = add_extent_changeset(state, bits_to_clear, changeset, 0);
 	BUG_ON(ret < 0);
 	state->state &= ~bits_to_clear;