[PATCH RFC 3/7] md/raid1: convert to use bio_submit_split()

[Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>]

From: Yu Kuai <yukuai3@xxxxxxxxxx>

On the one hand unify bio split code, prepare to fix disordered split
IO; On the other hand fix missing blkcg_bio_issue_init() and
trace_block_split() for split IO.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
---
 drivers/md/raid1.c | 35 ++++++++++++++---------------------
 1 file changed, 14 insertions(+), 21 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 408c26398321..95196c8749f9 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1317,7 +1317,7 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
 	struct raid1_info *mirror;
 	struct bio *read_bio;
 	int max_sectors;
-	int rdisk, error;
+	int rdisk;
 	bool r1bio_existed = !!r1_bio;
 
 	/*
@@ -1376,16 +1376,13 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
 	}
 
 	if (max_sectors < bio_sectors(bio)) {
-		struct bio *split = bio_split(bio, max_sectors,
-					      gfp, &conf->bio_split);
-
-		if (IS_ERR(split)) {
-			error = PTR_ERR(split);
+		bio = bio_submit_split(bio, max_sectors,&conf->bio_split);
+		if (!bio) {
+			set_bit(R1BIO_Returned, &r1_bio->state);
 			goto err_handle;
 		}
-		bio_chain(split, bio);
-		submit_bio_noacct(bio);
-		bio = split;
+
+		bio->bi_opf &= ~REQ_NOMERGE;
 		r1_bio->master_bio = bio;
 		r1_bio->sectors = max_sectors;
 	}
@@ -1413,7 +1410,6 @@ static void raid1_read_request(struct mddev *mddev, struct bio *bio,
 
 err_handle:
 	atomic_dec(&mirror->rdev->nr_pending);
-	bio->bi_status = errno_to_blk_status(error);
 	set_bit(R1BIO_Uptodate, &r1_bio->state);
 	raid_end_bio_io(r1_bio);
 }
@@ -1457,7 +1453,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 {
 	struct r1conf *conf = mddev->private;
 	struct r1bio *r1_bio;
-	int i, disks, k, error;
+	int i, disks, k;
 	unsigned long flags;
 	int first_clone;
 	int max_sectors;
@@ -1562,7 +1558,8 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 				 * the benefit.
 				 */
 				if (bio->bi_opf & REQ_ATOMIC) {
-					error = -EIO;
+					bio->bi_status =
+						errno_to_blk_status(-EIO);
 					goto err_handle;
 				}
 
@@ -1584,16 +1581,13 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 		max_sectors = min_t(int, max_sectors,
 				    BIO_MAX_VECS * (PAGE_SIZE >> 9));
 	if (max_sectors < bio_sectors(bio)) {
-		struct bio *split = bio_split(bio, max_sectors,
-					      GFP_NOIO, &conf->bio_split);
-
-		if (IS_ERR(split)) {
-			error = PTR_ERR(split);
+		bio = bio_submit_split(bio, max_sectors, &conf->bio_split);
+		if (!bio) {
+			set_bit(R1BIO_Returned, &r1_bio->state);
 			goto err_handle;
 		}
-		bio_chain(split, bio);
-		submit_bio_noacct(bio);
-		bio = split;
+
+		bio->bi_opf &= ~REQ_NOMERGE;
 		r1_bio->master_bio = bio;
 		r1_bio->sectors = max_sectors;
 	}
@@ -1683,7 +1677,6 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 		}
 	}
 
-	bio->bi_status = errno_to_blk_status(error);
 	set_bit(R1BIO_Uptodate, &r1_bio->state);
 	raid_end_bio_io(r1_bio);
 }
-- 
2.39.2