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block/merge: count bytes instead of sectors

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Individual bv_len's may not be a sector size.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20220610195830.3574005-7-kbusch@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Keith Busch 2022-06-10 12:58:25 -07:00 • committed by Jens Axboe
parent 37fee2e42e
commit 67927d2201
1 changed files with 24 additions and 17 deletions
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41
block/blk-merge.c
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@ -201,11 +201,11 @@ static inline unsigned get_max_segment_size(const struct request_queue *q,
* @nsegs: [in,out] Number of segments in the bio being built. Incremented * @nsegs: [in,out] Number of segments in the bio being built. Incremented
* by the number of segments from @bv that may be appended to that * by the number of segments from @bv that may be appended to that
* bio without exceeding @max_segs * bio without exceeding @max_segs
* @sectors: [in,out] Number of sectors in the bio being built. Incremented * @bytes: [in,out] Number of bytes in the bio being built. Incremented
* by the number of sectors from @bv that may be appended to that * by the number of bytes from @bv that may be appended to that
* bio without exceeding @max_sectors * bio without exceeding @max_bytes
* @max_segs: [in] upper bound for *@nsegs * @max_segs: [in] upper bound for *@nsegs
* @max_sectors: [in] upper bound for *@sectors * @max_bytes: [in] upper bound for *@bytes
* *
* When splitting a bio, it can happen that a bvec is encountered that is too * When splitting a bio, it can happen that a bvec is encountered that is too
* big to fit in a single segment and hence that it has to be split in the * big to fit in a single segment and hence that it has to be split in the
@ -216,10 +216,10 @@ static inline unsigned get_max_segment_size(const struct request_queue *q,
*/ */
static bool bvec_split_segs(const struct request_queue *q, static bool bvec_split_segs(const struct request_queue *q,
const struct bio_vec *bv, unsigned *nsegs, const struct bio_vec *bv, unsigned *nsegs,
unsigned *sectors, unsigned max_segs, unsigned *bytes, unsigned max_segs,
unsigned max_sectors) unsigned max_bytes)
{ {
unsigned max_len = (min(max_sectors, UINT_MAX >> 9) - *sectors) << 9; unsigned max_len = min(max_bytes, UINT_MAX) - *bytes;
unsigned len = min(bv->bv_len, max_len); unsigned len = min(bv->bv_len, max_len);
unsigned total_len = 0; unsigned total_len = 0;
unsigned seg_size = 0; unsigned seg_size = 0;
@ -237,7 +237,7 @@ static bool bvec_split_segs(const struct request_queue *q,
break; break;
} }
*sectors += total_len >> 9; *bytes += total_len;
/* tell the caller to split the bvec if it is too big to fit */ /* tell the caller to split the bvec if it is too big to fit */
return len > 0 || bv->bv_len > max_len; return len > 0 || bv->bv_len > max_len;
@ -269,8 +269,8 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
{ {
struct bio_vec bv, bvprv, *bvprvp = NULL; struct bio_vec bv, bvprv, *bvprvp = NULL;
struct bvec_iter iter; struct bvec_iter iter;
unsigned nsegs = 0, sectors = 0; unsigned nsegs = 0, bytes = 0;
const unsigned max_sectors = get_max_io_size(q, bio); const unsigned max_bytes = get_max_io_size(q, bio) << 9;
const unsigned max_segs = queue_max_segments(q); const unsigned max_segs = queue_max_segments(q);
bio_for_each_bvec(bv, bio, iter) { bio_for_each_bvec(bv, bio, iter) {
@ -282,12 +282,12 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
goto split; goto split;
if (nsegs < max_segs && if (nsegs < max_segs &&
sectors + (bv.bv_len >> 9) <= max_sectors && bytes + bv.bv_len <= max_bytes &&
bv.bv_offset + bv.bv_len <= PAGE_SIZE) { bv.bv_offset + bv.bv_len <= PAGE_SIZE) {
nsegs++; nsegs++;
sectors += bv.bv_len >> 9; bytes += bv.bv_len;
} else if (bvec_split_segs(q, &bv, &nsegs, &sectors, max_segs, } else if (bvec_split_segs(q, &bv, &nsegs, &bytes, max_segs,
max_sectors)) { max_bytes)) {
goto split; goto split;
} }
@ -300,13 +300,20 @@ static struct bio *blk_bio_segment_split(struct request_queue *q,
split: split:
*segs = nsegs; *segs = nsegs;
/*
* Individual bvecs might not be logical block aligned. Round down the
* split size so that each bio is properly block size aligned, even if
* we do not use the full hardware limits.
*/
bytes = ALIGN_DOWN(bytes, queue_logical_block_size(q));
/* /*
* Bio splitting may cause subtle trouble such as hang when doing sync * Bio splitting may cause subtle trouble such as hang when doing sync
* iopoll in direct IO routine. Given performance gain of iopoll for * iopoll in direct IO routine. Given performance gain of iopoll for
* big IO can be trival, disable iopoll when split needed. * big IO can be trival, disable iopoll when split needed.
*/ */
bio_clear_polled(bio); bio_clear_polled(bio);
return bio_split(bio, sectors, GFP_NOIO, bs); return bio_split(bio, bytes >> SECTOR_SHIFT, GFP_NOIO, bs);
} }
/** /**
@ -375,7 +382,7 @@ EXPORT_SYMBOL(blk_queue_split);
unsigned int blk_recalc_rq_segments(struct request *rq) unsigned int blk_recalc_rq_segments(struct request *rq)
{ {
unsigned int nr_phys_segs = 0; unsigned int nr_phys_segs = 0;
unsigned int nr_sectors = 0; unsigned int bytes = 0;
struct req_iterator iter; struct req_iterator iter;
struct bio_vec bv; struct bio_vec bv;
@ -398,7 +405,7 @@ unsigned int blk_recalc_rq_segments(struct request *rq)
} }
rq_for_each_bvec(bv, rq, iter) rq_for_each_bvec(bv, rq, iter)
bvec_split_segs(rq->q, &bv, &nr_phys_segs, &nr_sectors, bvec_split_segs(rq->q, &bv, &nr_phys_segs, &bytes,
UINT_MAX, UINT_MAX); UINT_MAX, UINT_MAX);
return nr_phys_segs; return nr_phys_segs;
} }