exofs: use bio_clone_fast in _write_mirror

The mirroring code never changes the bio data or biovecs.  This means
we can reuse the biovec allocation easily instead of duplicating it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by Boaz Harrosh <ooo@electrozaur.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/exofs/ore.c

@@ -873,8 +873,8 @@ static int _write_mirror(struct ore_io_state *ios, int cur_comp)
 			struct bio *bio;
 
 			if (per_dev != master_dev) {
-				bio = bio_clone_kmalloc(master_dev->bio,
-							GFP_KERNEL);
+				bio = bio_clone_fast(master_dev->bio,
+						     GFP_KERNEL, NULL);
 				if (unlikely(!bio)) {
 					ORE_DBGMSG(
 					      "Failed to allocate BIO size=%u\n",