[SRU][K:master-next][PATCH 1/1] block: handle bio_split_to_limits() NULL return

[Alexander Mikhalitsyn]

From: Jens Axboe <axboe at kernel.dk>

BugLink: https://bugs.launchpad.net/bugs/2020901

commit 613b14884b8595e20b9fac4126bf627313827fbe upstream.

This can't happen right now, but in preparation for allowing
bio_split_to_limits() returning NULL if it ended the bio, check for it
in all the callers.

Signed-off-by: Jens Axboe <axboe at kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(backported from commit 613b14884b8595e20b9fac4126bf627313827fbe)
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn at canonical.com>
---
 block/blk-merge.c             | 4 +++-
 block/blk-mq.c                | 3 +++
 drivers/block/drbd/drbd_req.c | 2 ++
 drivers/block/pktcdvd.c       | 2 ++
 drivers/block/ps3vram.c       | 2 ++
 drivers/md/dm.c               | 2 ++
 drivers/md/md.c               | 2 ++
 drivers/nvme/host/multipath.c | 2 ++
 drivers/s390/block/dcssblk.c  | 2 ++
 9 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 88e39b955bd6..1af8043900f4 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -348,11 +348,13 @@ void __blk_queue_split(struct request_queue *q, struct bio **bio,
 		break;
 	default:
 		split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs);
+		if (IS_ERR(split))
+			*bio = split = 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);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 7c7e632871e7..8b22429cf94e 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2818,6 +2818,9 @@ void blk_mq_submit_bio(struct bio *bio)
 	if (blk_may_split(q, bio))
 		__blk_queue_split(q, &bio, &nr_segs);
 
+	if (!bio)
+		return;
+
 	if (!bio_integrity_prep(bio))
 		return;
 
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index e60d3c6314c6..f323a4714f6a 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1609,6 +1609,8 @@ void drbd_submit_bio(struct bio *bio)
 	struct drbd_device *device = bio->bi_bdev->bd_disk->private_data;
 
 	blk_queue_split(&bio);
+	if (!bio)
+		return;
 
 	/*
 	 * what we "blindly" assume:
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 789093375344..1988bb05c0c7 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -2400,6 +2400,8 @@ static void pkt_submit_bio(struct bio *bio)
 	struct bio *split;
 
 	blk_queue_split(&bio);
+	if (!bio)
+		return;
 
 	pkt_dbg(2, pd, "start = %6llx stop = %6llx\n",
 		(unsigned long long)bio->bi_iter.bi_sector,
diff --git a/drivers/block/ps3vram.c b/drivers/block/ps3vram.c
index 4f90819e245e..2a431178dc7e 100644
--- a/drivers/block/ps3vram.c
+++ b/drivers/block/ps3vram.c
@@ -587,6 +587,8 @@ static void ps3vram_submit_bio(struct bio *bio)
 	dev_dbg(&dev->core, "%s\n", __func__);
 
 	blk_queue_split(&bio);
+	if (!bio)
+		return;
 
 	spin_lock_irq(&priv->lock);
 	busy = !bio_list_empty(&priv->list);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 5acee96b5a7b..bf904c153d41 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1674,6 +1674,8 @@ static void dm_split_and_process_bio(struct mapped_device *md,
 		 * otherwise associated queue_limits won't be imposed.
 		 */
 		blk_queue_split(&bio);
+		if (!bio)
+			return;
 	}
 
 	init_clone_info(&ci, md, map, bio, is_abnormal);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 946434ced070..772a89843226 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -465,6 +465,8 @@ static void md_submit_bio(struct bio *bio)
 	}
 
 	blk_queue_split(&bio);
+	if (!bio)
+		return;
 
 	if (mddev->ro == 1 && unlikely(rw == WRITE)) {
 		if (bio_sectors(bio) != 0)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index d62c4a0f89ab..571c4791faa8 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -351,6 +351,8 @@ static void nvme_ns_head_submit_bio(struct bio *bio)
 	 * pool from the original queue to allocate the bvecs from.
 	 */
 	blk_queue_split(&bio);
+	if (!bio)
+		return;
 
 	srcu_idx = srcu_read_lock(&head->srcu);
 	ns = nvme_find_path(head);
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index f4401b2d30e0..18506cc222ba 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -865,6 +865,8 @@ dcssblk_submit_bio(struct bio *bio)
 	unsigned long bytes_done;
 
 	blk_queue_split(&bio);
+	if (!bio)
+		return;
 
 	bytes_done = 0;
 	dev_info = bio->bi_bdev->bd_disk->private_data;
-- 
2.34.1