[PATCHv4 7/9] block/bounce: count bytes instead of sectors

Keith Busch
2022-05-26T01:08:46Z

From: Keith Busch <kbusch@kernel.org>

Individual bv_len's may not be a sector size.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
v3->v4:

Use sector shift

Add comment explaing the ALIGN_DOWN

Use unsigned int type for counting bytes

block/bounce.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/block/bounce.c b/block/bounce.c
index 8f7b6fe3b4db..f6ae21ec2a70 100644
--- a/block/bounce.c
+++ b/block/bounce.c
@@ -205,19 +205,25 @@ void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
int rw = bio_data_dir(*bio_orig);
struct bio_vec *to, from;
struct bvec_iter iter;
- unsigned i = 0;
+ unsigned i = 0, bytes = 0;
bool bounce = false;
- int sectors = 0;
+ int sectors;

bio_for_each_segment(from, *bio_orig, iter) {
if (i++ < BIO_MAX_VECS)
- sectors += from.bv_len >> 9;
+ bytes += from.bv_len;
if (PageHighMem(from.bv_page))
bounce = true;
}
if (!bounce)
return;

+ /*
+ * If the original has more than BIO_MAX_VECS biovecs, the total bytes
+ * may not be block size aligned. Align down to ensure both sides of
+ * the split bio are appropriately sized.
+ */
+ sectors = ALIGN_DOWN(bytes, queue_logical_block_size(q)) >> SECTOR_SHIFT;
if (sectors < bio_sectors(*bio_orig)) {
bio = bio_split(*bio_orig, sectors, GFP_NOIO, &bounce_bio_split);
bio_chain(bio, *bio_orig);
--
2.30.2