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block: Fix page_is_mergeable() for compound pages 

[ Upstream commit d81665198b ]

If we pass in an offset which is larger than PAGE_SIZE, then
page_is_mergeable() thinks it's not mergeable with the previous bio_vec,
leading to a large number of bio_vecs being used.  Use a slightly more
obvious test that the two pages are compatible with each other.

Fixes: 52d52d1c98 ("block: only allow contiguous page structs in a bio_vec")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Matthew Wilcox (Oracle) 2020-08-17 20:52:06 +01:00 committed by Greg Kroah-Hartman
parent 3e9eb1e893
commit 2295664518
1 changed files with 5 additions and 5 deletions
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10
block/bio.c
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@ -683,8 +683,8 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
struct page *page, unsigned int len, unsigned int off,
bool *same_page)
{
phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) +
bv->bv_offset + bv->bv_len - 1;
size_t bv_end = bv->bv_offset + bv->bv_len;
phys_addr_t vec_end_addr = page_to_phys(bv->bv_page) + bv_end - 1;
phys_addr_t page_addr = page_to_phys(page);
if (vec_end_addr + 1 != page_addr + off)
@ -693,9 +693,9 @@ static inline bool page_is_mergeable(const struct bio_vec *bv,
return false;
*same_page = ((vec_end_addr & PAGE_MASK) == page_addr);
if (!*same_page && pfn_to_page(PFN_DOWN(vec_end_addr)) + 1 != page)
return false;
return true;
if (*same_page)
return true;
return (bv->bv_page + bv_end / PAGE_SIZE) == (page + off / PAGE_SIZE);
}
static bool bio_try_merge_pc_page(struct request_queue *q, struct bio *bio,