md/raid1: remove unnecessary null checking

If %__GFP_DIRECT_RECLAIM is set then bio_alloc_bioset will always
be able to allocate a bio. See comment of bio_alloc_bioset.

Signed-off-by: Gou Hao <gouhao@uniontech.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20231214151458.28970-1-gouhao@uniontech.com

drivers/md/raid1.c

@@ -1124,8 +1124,6 @@ static void alloc_behind_master_bio(struct r1bio *r1_bio,
 
 	behind_bio = bio_alloc_bioset(NULL, vcnt, 0, GFP_NOIO,
 				      &r1_bio->mddev->bio_set);
-	if (!behind_bio)
-		return;
 
 	/* discard op, we don't support writezero/writesame yet */
 	if (!bio_has_data(bio)) {