Merge tag 'block-2023-01-06' of git://git.kernel.dk/linux

Pull block fixes from Jens Axboe:
 "The big change here is obviously the revert of the pktcdvd driver
  removal. Outside of that, just minor tweaks. In detail:

   - Re-instate the pktcdvd driver, which necessitates adding back
     bio_copy_data_iter() and the fops->devnode() hook for now (me)

   - Fix for splitting of a bio marked as NOWAIT, causing either nowait
     reads or writes to error with EAGAIN even if parts of the IO
     completed (me)

   - Fix for ublk, punting management commands to io-wq as they can all
     easily block for extended periods of time (Ming)

   - Removal of SRCU dependency for the block layer (Paul)"

* tag 'block-2023-01-06' of git://git.kernel.dk/linux:
  block: Remove "select SRCU"
  Revert "pktcdvd: remove driver."
  Revert "block: remove devnode callback from struct block_device_operations"
  Revert "block: bio_copy_data_iter"
  ublk: honor IO_URING_F_NONBLOCK for handling control command
  block: don't allow splitting of a REQ_NOWAIT bio
  block: handle bio_split_to_limits() NULL return

1 files changed, 13 insertions, 1 deletions

diff --git a/block/blk-merge.c b/block/blk-merge.c
index 35a8f75cc45d..b7c193d67185 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -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;
 
 	/*
@@ -358,11 +368,13 @@ 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);