bcachefs: Initialize bch_write_op->failed in inline data path

Normally this is initialized in __bch2_write(), which is executed in a
loop, but the inline data path skips this.

Reported-by: syzbot+fd3ccb331eb21f05d13b@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/io_write.c

@@ -1513,6 +1513,8 @@ static void bch2_write_data_inline(struct bch_write_op *op, unsigned data_len)
 	unsigned sectors;
 	int ret;
 
+	memset(&op->failed, 0, sizeof(op->failed));
+
 	op->flags |= BCH_WRITE_WROTE_DATA_INLINE;
 	op->flags |= BCH_WRITE_DONE;