[dm-devel] [dm-6.4 PATCH v3 11/20] dm bufio: use multi-page bio vector

Mike Snitzer
2023-03-27T20:13:53Z

From: Mikulas Patocka <mpatocka@redhat.com>

The kernel supports multi page bio vector entries, so we can use them
in dm-bufio as an optimization.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
---
drivers/md/dm-bufio.c | 24 ++++--------------------
1 file changed, 4 insertions(+), 20 deletions(-)

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index cca43ed13fd1..ae552644a0b4 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1312,19 +1312,14 @@ static void use_bio(struct dm_buffer *b, enum req_op op, sector_t sector,
{
struct bio *bio;
char *ptr;
- unsigned int vec_size, len;
+ unsigned int len;

- vec_size = b->c->block_size >> PAGE_SHIFT;
- if (unlikely(b->c->sectors_per_block_bits < PAGE_SHIFT - SECTOR_SHIFT))
- vec_size += 2;
-
- bio = bio_kmalloc(vec_size, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN);
+ bio = bio_kmalloc(1, GFP_NOWAIT | __GFP_NORETRY | __GFP_NOWARN);
if (!bio) {
-dmio:
use_dmio(b, op, sector, n_sectors, offset);
return;
}
- bio_init(bio, b->c->bdev, bio->bi_inline_vecs, vec_size, op);
+ bio_init(bio, b->c->bdev, bio->bi_inline_vecs, 1, op);
bio->bi_iter.bi_sector = sector;
bio->bi_end_io = bio_complete;
bio->bi_private = b;
@@ -1332,18 +1327,7 @@ static void use_bio(struct dm_buffer *b, enum req_op op, sector_t sector,
ptr = (char *)b->data + offset;
len = n_sectors << SECTOR_SHIFT;

- do {
- unsigned int this_step = min((unsigned int)(PAGE_SIZE - offset_in_page(ptr)), len);
-
- if (!bio_add_page(bio, virt_to_page(ptr), this_step,
- offset_in_page(ptr))) {
- bio_put(bio);
- goto dmio;
- }
-
- len -= this_step;
- ptr += this_step;
- } while (len > 0);
+ __bio_add_page(bio, virt_to_page(ptr), len, offset_in_page(ptr));

submit_bio(bio);