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block: create a bio_try_merge_pc_page helper 

Passsthrough bio handling should be the same as normal bio handling,
except that we need to take hardware limitations into account.  Thus
use the common try_merge implementation after checking the hardware
limits.  This changes behavior in that we now also check segment
and dma boundary settings for same page merges, which is a little
more work but has no effect as those need to be larger than the
page size.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2019-08-12 17:39:57 +02:00 committed by Jens Axboe
parent 320ea869a1
commit 384209cd5b
1 changed files with 10 additions and 24 deletions
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34
block/bio.c
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@ -646,25 +646,20 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
return true;
}
/*
* Check if the @page can be added to the current segment(@bv), and make
* sure to call it only if page_is_mergeable(@bv, @page) is true
*/
static bool can_add_page_to_seg(struct request_queue *q,
struct bio_vec *bv, struct page *page, unsigned len,
unsigned offset)
static bool bio_try_merge_pc_page(struct request_queue *q, struct bio *bio,
struct page *page, unsigned len, unsigned offset,
bool *same_page)
{
struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1];
unsigned long mask = queue_segment_boundary(q);
phys_addr_t addr1 = page_to_phys(bv->bv_page) + bv->bv_offset;
phys_addr_t addr2 = page_to_phys(page) + offset + len - 1;
if ((addr1 | mask) != (addr2 | mask))
return false;
if (bv->bv_len + len > queue_max_segment_size(q))
return false;
return true;
return __bio_try_merge_page(bio, page, len, offset, same_page);
}
/**
@ -700,26 +695,18 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
return 0;
if (bio->bi_vcnt > 0) {
bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (page == bvec->bv_page &&
offset == bvec->bv_offset + bvec->bv_len) {
if (put_same_page)
if (bio_try_merge_pc_page(q, bio, page, len, offset,
&same_page)) {
if (put_same_page && same_page)
put_page(page);
bvec->bv_len += len;
goto done;
}
if (page_is_mergeable(bvec, page, len, offset, &same_page) &&
can_add_page_to_seg(q, bvec, page, len, offset)) {
bvec->bv_len += len;
goto done;
return len;
}
/*
* If the queue doesn't support SG gaps and adding this segment
* would create a gap, disallow it.
*/
bvec = &bio->bi_io_vec[bio->bi_vcnt - 1];
if (bvec_gap_to_prev(q, bvec, offset))
return 0;
}
@ -735,7 +722,6 @@ static int __bio_add_pc_page(struct request_queue *q, struct bio *bio,
bvec->bv_len = len;
bvec->bv_offset = offset;
bio->bi_vcnt++;
done:
bio->bi_iter.bi_size += len;
return len;
}