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ANDROID: block: Add support for filesystem requests and small segments

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Add support in the bio splitting code and also in the bio submission code
for bios with segments smaller than the page size.

Bug: 308663717
Bug: 319125789
Change-Id: Iea511675ad96b0c8255c2b87811ad33c3a02c8fa
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
[jyescas@google.com: the function bio_may_exceed_limits() does not
                     exists in the 5.15 kernel, so the sub page limit
                     code in block/blk.h was moved to the function
                     __blk_queue_split() in block/blk-merge.c]
Signed-off-by: Juan Yescas <jyescas@google.com>
This commit is contained in:
Bart Van Assche
2023-06-12 13:33:12 -07:00
committed by Juan Yescas
parent e99e7de8a6
commit bed88e7c4f
1 changed files with 12 additions and 9 deletions
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21
block/blk-merge.c
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@@ -265,7 +265,8 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
if (nsegs < max_segs &&
sectors + (bv.bv_len >> 9) <= max_sectors &&
bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
nsegs++;
/* single-page bvec optimization */
nsegs += blk_segments(&q->limits, bv.bv_len);
sectors += bv.bv_len >> 9;
} else if (bvec_split_segs(q, &bv, &nsegs, &sectors, max_segs,
max_sectors)) {
@@ -333,18 +334,17 @@ void __blk_queue_split(struct bio **bio, unsigned int *nr_segs)
break;
default:
/*
* All drivers must accept single-segments bios that are <=
* PAGE_SIZE. This is a quick and dirty check that relies on
* the fact that bi_io_vec[0] is always valid if a bio has data.
* The check might lead to occasional false negatives when bios
* are cloned, but compared to the performance impact of cloned
* bios themselves the loop below doesn't matter anyway.
* Check whether bio splitting should be performed. This check may
* trigger the bio splitting code even if splitting is not necessary.
*/
if (!q->limits.chunk_sectors &&
(*bio)->bi_vcnt == 1 &&
(!blk_queue_sub_page_limits(&q->limits) ||
(*bio)->bi_io_vec->bv_len <= q->limits.max_segment_size) &&
((*bio)->bi_io_vec[0].bv_len +
(*bio)->bi_io_vec[0].bv_offset) <= PAGE_SIZE) {
*nr_segs = 1;
*nr_segs = blk_segments(&q->limits,
(*bio)->bi_io_vec[0].bv_len);
break;
}
split = blk_bio_segment_split(q, *bio, &q->bio_split, nr_segs);
@@ -519,7 +519,10 @@ static int __blk_bios_map_sg(struct request_queue *q, struct bio *bio,
__blk_segment_map_sg_merge(q, &bvec, &bvprv, sg))
goto next_bvec;
if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE)
if (bvec.bv_offset + bvec.bv_len <= PAGE_SIZE &&
(!blk_queue_sub_page_limits(&q->limits) ||
bvec.bv_len <= q->limits.max_segment_size))
/* single-segment bvec optimization */
nsegs += __blk_bvec_map_sg(bvec, sglist, sg);
else
nsegs += blk_bvec_map_sg(q, &bvec, sglist, sg);