dm-io: Warn on creating multiple atomic write bios for a region

A region should just be for a single atomic write, so warn when we are
creating many. This should not occur if request queue limits are properly
configured.

Signed-off-by: John Garry <[e-mail]>
Reviewed-by: Mike Snitzer <[e-mail]>
Signed-off-by: Mikulas Patocka <[e-mail]>

drivers/md/dm-io.c

···
 
 		atomic_inc(&io->count);
 		submit_bio(bio);
+		WARN_ON_ONCE(opf & REQ_ATOMIC && remaining);
 	} while (remaining);
 }