| Message ID | 20200817195206.15172-1-willy@infradead.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | block: Fix page_is_mergeable() for compound pages | expand |
On Mon, Aug 17, 2020 at 08:52:06PM +0100, Matthew Wilcox (Oracle) wrote: > 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. > > Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> > Fixes: 52d52d1c98a9 ("block: only allow contiguous page structs in a bio_vec") > > --- > block/bio.c | 10 +++++----- > 1 file changed, 5 insertions(+), 5 deletions(-) > > diff --git a/block/bio.c b/block/bio.c > index c63ba04bd629..a9931f23d933 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -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; > - return true; > + if (*same_page) > + return true; > + return (bv->bv_page + bv_end / PAGE_SIZE) == (page + off / PAGE_SIZE); Looks this way is more straightforward, meantime can cover compound pages: Reviewed-by: Ming Lei <ming.lei@redhat.com> Thanks, Ming
On 8/17/20 12:52 PM, Matthew Wilcox (Oracle) wrote: > 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. Applied, thanks.
diff --git a/block/bio.c b/block/bio.c index c63ba04bd629..a9931f23d933 100644 --- a/block/bio.c +++ b/block/bio.c @@ -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; - return true; + if (*same_page) + return true; + return (bv->bv_page + bv_end / PAGE_SIZE) == (page + off / PAGE_SIZE); } /*
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. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Fixes: 52d52d1c98a9 ("block: only allow contiguous page structs in a bio_vec") --- block/bio.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)