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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: I056659cf86c04fb095aa01cd3d274d29417782ac
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
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 879eff2954
commit 8a2f432fcb
3 changed files with 13 additions and 8 deletions
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8
block/blk-merge.c
View File

@ -285,7 +285,8 @@ static struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
if (nsegs < lim->max_segments &&
bytes + bv.bv_len <= max_bytes &&
bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
nsegs++;
/* single-page bvec optimization */
nsegs += blk_segments(lim, bv.bv_len);
bytes += bv.bv_len;
} else {
if (bvec_split_segs(lim, &bv, &nsegs, &bytes,
@ -533,7 +534,10 @@ 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);

2
block/blk-mq.c
View File

@ -2951,6 +2951,8 @@ void blk_mq_submit_bio(struct bio *bio)
bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);
if (!bio)
return;
} else if (bio->bi_vcnt == 1) {
nr_segs = blk_segments(&q->limits, bio->bi_io_vec[0].bv_len);
}
if (!bio_integrity_prep(bio))

11
block/blk.h
View File

@ -337,13 +337,12 @@ static inline bool bio_may_exceed_limits(struct bio *bio,
}
/*
* 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 (blk_queue_sub_page_limits(lim) && bio->bi_io_vec &&
bio->bi_io_vec->bv_len > lim->max_segment_size)
return true;
return lim->chunk_sectors || bio->bi_vcnt != 1 ||
bio->bi_io_vec->bv_len + bio->bi_io_vec->bv_offset > PAGE_SIZE;
}