block: Fix page_is_mergeable() for compound pages (d8166519) · Commits · 戴 / test

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: ("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>

block/bio.c

+5 −5

Original line number	Diff line number	Diff line
		@@ -740,8 +740,8 @@ 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)
		@@ -750,9 +750,9 @@ 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;
		if (*same_page)
		return true;
		return (bv->bv_page + bv_end / PAGE_SIZE) == (page + off / PAGE_SIZE);
		}

		/*

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