From: Christoph Hellwig <hch@lst.de>
Date: Wed, 2 Feb 2022 17:01:04 +0100
Subject: [PATCH] dm: simplify the single bio fast path in
__send_duplicate_bios
Git-commit: 891fced644a7529bfd4b1436b2341527ce8f68ad
Patch-mainline: v5.18-rc1
References: jsc#PED-1183
Most targets just need a single flush bio. Open code that case in
__send_duplicate_bios without the need to add the bio to a list.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <snitzer@redhat.com>
Link: https://lore.kernel.org/r/20220202160109.108149-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/md/dm.c | 26 ++++++++++++++------------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index c05b6ff1bb95..78df75f57288 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1241,15 +1241,6 @@ static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
struct bio *bio;
int try;
- if (!num_bios)
- return;
-
- if (num_bios == 1) {
- bio = alloc_tio(ci, ti, 0, len, GFP_NOIO);
- bio_list_add(blist, bio);
- return;
- }
-
for (try = 0; try < 2; try++) {
int bio_nr;
@@ -1279,12 +1270,23 @@ static void __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
struct bio_list blist = BIO_EMPTY_LIST;
struct bio *clone;
- alloc_multiple_bios(&blist, ci, ti, num_bios, len);
-
- while ((clone = bio_list_pop(&blist))) {
+ switch (num_bios) {
+ case 0:
+ break;
+ case 1:
+ clone = alloc_tio(ci, ti, 0, len, GFP_NOIO);
if (len)
bio_setup_sector(clone, ci->sector, *len);
__map_bio(clone);
+ break;
+ default:
+ alloc_multiple_bios(&blist, ci, ti, num_bios, len);
+ while ((clone = bio_list_pop(&blist))) {
+ if (len)
+ bio_setup_sector(clone, ci->sector, *len);
+ __map_bio(clone);
+ }
+ break;
}
}
--
2.35.3