block: Error an attempt to split an atomic write in bio_split()

This is disallowed.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20241111112150.3756529-3-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: johnpgarry

block/bio.c

@@ -1674,6 +1674,10 @@ struct bio *bio_split(struct bio *bio, int sectors,
 	if (WARN_ON_ONCE(bio_op(bio) == REQ_OP_ZONE_APPEND))
 		return ERR_PTR(-EINVAL);
 
+	/* atomic writes cannot be split */
+	if (bio->bi_opf & REQ_ATOMIC)
+		return ERR_PTR(-EINVAL);
+
 	split = bio_alloc_clone(bio->bi_bdev, bio, gfp, bs);
 	if (!split)
 		return ERR_PTR(-ENOMEM);