[PATCH v3 1/4] brd: use a switch statement in brd_submit_bio

[Mikulas Patocka <mpatocka@redhat.com>]

Use a switch statement in brd_submit_bio, so that the code will look
better when we add support for more bio operations.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 drivers/block/brd.c |   43 ++++++++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 17 deletions(-)

Index: linux-2.6/drivers/block/brd.c
===================================================================
--- linux-2.6.orig/drivers/block/brd.c
+++ linux-2.6/drivers/block/brd.c
@@ -243,29 +243,38 @@ out:
 static void brd_submit_bio(struct bio *bio)
 {
 	struct brd_device *brd = bio->bi_bdev->bd_disk->private_data;
-	sector_t sector = bio->bi_iter.bi_sector;
+	sector_t sector;
 	struct bio_vec bvec;
 	struct bvec_iter iter;
 
-	bio_for_each_segment(bvec, bio, iter) {
-		unsigned int len = bvec.bv_len;
-		int err;
+	switch (bio_op(bio)) {
+		case REQ_OP_READ:
+		case REQ_OP_WRITE:
+			sector = bio->bi_iter.bi_sector;
+			bio_for_each_segment(bvec, bio, iter) {
+				unsigned int len = bvec.bv_len;
+				int err;
 
-		/* Don't support un-aligned buffer */
-		WARN_ON_ONCE((bvec.bv_offset & (SECTOR_SIZE - 1)) ||
-				(len & (SECTOR_SIZE - 1)));
+				/* Don't support un-aligned buffer */
+				WARN_ON_ONCE((bvec.bv_offset & (SECTOR_SIZE - 1)) ||
+						(len & (SECTOR_SIZE - 1)));
 
-		err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset,
-				  bio->bi_opf, sector);
-		if (err) {
-			if (err == -ENOMEM && bio->bi_opf & REQ_NOWAIT) {
-				bio_wouldblock_error(bio);
-				return;
+				err = brd_do_bvec(brd, bvec.bv_page, len, bvec.bv_offset,
+						  bio->bi_opf, sector);
+				if (err) {
+					if (err == -ENOMEM && bio->bi_opf & REQ_NOWAIT) {
+						bio_wouldblock_error(bio);
+						return;
+					}
+					bio_io_error(bio);
+					return;
+				}
+				sector += len >> SECTOR_SHIFT;
 			}
-			bio_io_error(bio);
-			return;
-		}
-		sector += len >> SECTOR_SHIFT;
+			break;
+		default:
+			bio->bi_status = BLK_STS_NOTSUPP;
+			break;
 	}
 
 	bio_endio(bio);