1 files changed, 48 insertions, 4 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 35a8f75cc45d..1ac782fdc55c 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -276,7 +276,7 @@ static bool bvec_split_segs(const struct queue_limits *lim,
  * responsible for ensuring that @bs is only destroyed after processing of the
  * split bio has finished.
  */
-static struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
+struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
 		unsigned *segs, struct bio_set *bs, unsigned max_bytes)
 {
 	struct bio_vec bv, bvprv, *bvprvp = NULL;
@@ -309,6 +309,16 @@ static struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
 	*segs = nsegs;
 	return NULL;
 split:
+	/*
+	 * We can't sanely support splitting for a REQ_NOWAIT bio. End it
+	 * with EAGAIN if splitting is required and return an error pointer.
+	 */
+	if (bio->bi_opf & REQ_NOWAIT) {
+		bio->bi_status = BLK_STS_AGAIN;
+		bio_endio(bio);
+		return ERR_PTR(-EAGAIN);
+	}
+
 	*segs = nsegs;
 
 	/*
@@ -326,6 +336,7 @@ split:
 	bio_clear_polled(bio);
 	return bio_split(bio, bytes >> SECTOR_SHIFT, GFP_NOIO, bs);
 }
+EXPORT_SYMBOL_GPL(bio_split_rw);
 
 /**
  * __bio_split_to_limits - split a bio to fit the queue limits
@@ -358,11 +369,13 @@ struct bio *__bio_split_to_limits(struct bio *bio,
 	default:
 		split = bio_split_rw(bio, lim, nr_segs, bs,
 				get_max_io_size(bio, lim) << SECTOR_SHIFT);
+		if (IS_ERR(split))
+			return NULL;
 		break;
 	}
 
 	if (split) {
-		/* there isn't chance to merge the splitted bio */
+		/* there isn't chance to merge the split bio */
 		split->bi_opf |= REQ_NOMERGE;
 
 		blkcg_bio_issue_init(split);
@@ -745,6 +758,33 @@ void blk_rq_set_mixed_merge(struct request *rq)
 	rq->rq_flags |= RQF_MIXED_MERGE;
 }
 
+static inline blk_opf_t bio_failfast(const struct bio *bio)
+{
+	if (bio->bi_opf & REQ_RAHEAD)
+		return REQ_FAILFAST_MASK;
+
+	return bio->bi_opf & REQ_FAILFAST_MASK;
+}
+
+/*
+ * After we are marked as MIXED_MERGE, any new RA bio has to be updated
+ * as failfast, and request's failfast has to be updated in case of
+ * front merge.
+ */
+static inline void blk_update_mixed_merge(struct request *req,
+		struct bio *bio, bool front_merge)
+{
+	if (req->rq_flags & RQF_MIXED_MERGE) {
+		if (bio->bi_opf & REQ_RAHEAD)
+			bio->bi_opf |= REQ_FAILFAST_MASK;
+
+		if (front_merge) {
+			req->cmd_flags &= ~REQ_FAILFAST_MASK;
+			req->cmd_flags |= bio->bi_opf & REQ_FAILFAST_MASK;
+		}
+	}
+}
+
 static void blk_account_io_merge_request(struct request *req)
 {
 	if (blk_do_io_stat(req)) {
@@ -942,7 +982,7 @@ enum bio_merge_status {
 static enum bio_merge_status bio_attempt_back_merge(struct request *req,
 		struct bio *bio, unsigned int nr_segs)
 {
-	const blk_opf_t ff = bio->bi_opf & REQ_FAILFAST_MASK;
+	const blk_opf_t ff = bio_failfast(bio);
 
 	if (!ll_back_merge_fn(req, bio, nr_segs))
 		return BIO_MERGE_FAILED;
@@ -953,6 +993,8 @@ static enum bio_merge_status bio_attempt_back_merge(struct request *req,
 	if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
 		blk_rq_set_mixed_merge(req);
 
+	blk_update_mixed_merge(req, bio, false);
+
 	req->biotail->bi_next = bio;
 	req->biotail = bio;
 	req->__data_len += bio->bi_iter.bi_size;
@@ -966,7 +1008,7 @@ static enum bio_merge_status bio_attempt_back_merge(struct request *req,
 static enum bio_merge_status bio_attempt_front_merge(struct request *req,
 		struct bio *bio, unsigned int nr_segs)
 {
-	const blk_opf_t ff = bio->bi_opf & REQ_FAILFAST_MASK;
+	const blk_opf_t ff = bio_failfast(bio);
 
 	if (!ll_front_merge_fn(req, bio, nr_segs))
 		return BIO_MERGE_FAILED;
@@ -977,6 +1019,8 @@ static enum bio_merge_status bio_attempt_front_merge(struct request *req,
 	if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
 		blk_rq_set_mixed_merge(req);
 
+	blk_update_mixed_merge(req, bio, true);
+
 	bio->bi_next = req->bio;
 	req->bio = bio;