raid5-cache: refactor bio allocation

Split out a helper to allocate a bio for log writes.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NShaohua Li <shli@fb.com>
Signed-off-by: NNeilBrown <neilb@suse.com>

drivers/md/raid5-cache.c

@@ -276,11 +276,25 @@ static void r5l_submit_current_io(struct r5l_log *log)
 	}
 }
 
+static struct bio *r5l_bio_alloc(struct r5l_log *log, struct r5l_io_unit *io)
+{
+	struct bio *bio = bio_kmalloc(GFP_NOIO | __GFP_NOFAIL, BIO_MAX_PAGES);
+
+	bio->bi_rw = WRITE;
+	bio->bi_bdev = log->rdev->bdev;
+	bio->bi_iter.bi_sector = log->log_start;
+	bio->bi_end_io = r5l_log_endio;
+	bio->bi_private = io;
+
+	bio_list_add(&io->bios, bio);
+	atomic_inc(&io->pending_io);
+	return bio;
+}
+
 static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
 {
 	struct r5l_io_unit *io;
 	struct r5l_meta_block *block;
-	struct bio *bio;
 
 	io = r5l_alloc_io_unit(log);
 
@@ -294,17 +308,8 @@ static struct r5l_io_unit *r5l_new_meta(struct r5l_log *log)
 	io->meta_offset = sizeof(struct r5l_meta_block);
 	io->seq = log->seq;
 
-	bio = bio_kmalloc(GFP_NOIO | __GFP_NOFAIL, BIO_MAX_PAGES);
-	io->current_bio = bio;
-	bio->bi_rw = WRITE;
-	bio->bi_bdev = log->rdev->bdev;
-	bio->bi_iter.bi_sector = log->log_start;
-	bio_add_page(bio, io->meta_page, PAGE_SIZE, 0);
-	bio->bi_end_io = r5l_log_endio;
-	bio->bi_private = io;
-
-	bio_list_add(&io->bios, bio);
-	atomic_inc(&io->pending_io);
+	io->current_bio = r5l_bio_alloc(log, io);
+	bio_add_page(io->current_bio, io->meta_page, PAGE_SIZE, 0);
 
 	log->seq++;
 	log->log_start = r5l_ring_add(log, log->log_start, BLOCK_SECTORS);
@@ -358,19 +363,9 @@ static void r5l_append_payload_page(struct r5l_log *log, struct page *page)
 	struct r5l_io_unit *io = log->current_io;
 
 alloc_bio:
-	if (!io->current_bio) {
-		struct bio *bio;
-
-		bio = bio_kmalloc(GFP_NOIO | __GFP_NOFAIL, BIO_MAX_PAGES);
-		bio->bi_rw = WRITE;
-		bio->bi_bdev = log->rdev->bdev;
-		bio->bi_iter.bi_sector = log->log_start;
-		bio->bi_end_io = r5l_log_endio;
-		bio->bi_private = io;
-		bio_list_add(&io->bios, bio);
-		atomic_inc(&io->pending_io);
-		io->current_bio = bio;
-	}
+	if (!io->current_bio)
+		io->current_bio = r5l_bio_alloc(log, io);
+
 	if (!bio_add_page(io->current_bio, page, PAGE_SIZE, 0)) {
 		io->current_bio = NULL;
 		goto alloc_bio;