From: Matthew Wilcox (Oracle) willy@infradead.org
[ Upstream commit d81665198b83e55a28339d1f3e4890ed8a434556 ]
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: 52d52d1c98a9 ("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 --- block/bio.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/block/bio.c b/block/bio.c index 94d697217887a..87505a93bcff6 100644 --- a/block/bio.c +++ b/block/bio.c @@ -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,