btrfs: do not increment dirty_metadata_bytes in set_btree_ioerr

We only add if we set the extent buffer dirty, and we subtract when we
clear the extent buffer dirty.  If we end up in set_btree_ioerr we have
already cleared the buffer dirty, and we aren't resetting dirty on the
extent buffer, so this is simply wrong.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent_io.c

@@ -1911,13 +1911,6 @@ static void set_btree_ioerr(struct page *page, struct extent_buffer *eb)
 	 */
 	mapping_set_error(page->mapping, -EIO);
 
-	/*
-	 * If we error out, we should add back the dirty_metadata_bytes
-	 * to make it consistent.
-	 */
-	percpu_counter_add_batch(&fs_info->dirty_metadata_bytes,
-				 eb->len, fs_info->dirty_metadata_batch);
-
 	/*
 	 * If writeback for a btree extent that doesn't belong to a log tree
 	 * failed, increment the counter transaction->eb_write_errors.