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Message-Id: <20190411210834.4105-7-jglisse@redhat.com> Date: Thu, 11 Apr 2019 17:08:25 -0400 From: jglisse@...hat.com To: linux-kernel@...r.kernel.org Cc: Jérôme Glisse <jglisse@...hat.com>, linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org, linux-mm@...ck.org, John Hubbard <jhubbard@...dia.com>, Jan Kara <jack@...e.cz>, Dan Williams <dan.j.williams@...el.com>, Alexander Viro <viro@...iv.linux.org.uk>, Johannes Thumshirn <jthumshirn@...e.de>, Christoph Hellwig <hch@....de>, Jens Axboe <axboe@...nel.dk>, Ming Lei <ming.lei@...hat.com>, Dave Chinner <david@...morbit.com>, Jason Gunthorpe <jgg@...pe.ca>, Matthew Wilcox <willy@...radead.org> Subject: [PATCH v1 06/15] block: convert bio_vec.bv_page to bv_pfn to store pfn and not page From: Jérôme Glisse <jglisse@...hat.com> To be able to store flags with each bio_vec store the pfn value and not the page this leave us with couple uppers bits we can latter use for flags. Signed-off-by: Jérôme Glisse <jglisse@...hat.com> Cc: linux-fsdevel@...r.kernel.org Cc: linux-block@...r.kernel.org Cc: linux-mm@...ck.org Cc: John Hubbard <jhubbard@...dia.com> Cc: Jan Kara <jack@...e.cz> Cc: Dan Williams <dan.j.williams@...el.com> Cc: Alexander Viro <viro@...iv.linux.org.uk> Cc: Johannes Thumshirn <jthumshirn@...e.de> Cc: Christoph Hellwig <hch@....de> Cc: Jens Axboe <axboe@...nel.dk> Cc: Ming Lei <ming.lei@...hat.com> Cc: Dave Chinner <david@...morbit.com> Cc: Jason Gunthorpe <jgg@...pe.ca> Cc: Matthew Wilcox <willy@...radead.org> --- Documentation/block/biodoc.txt | 7 +++++-- include/linux/bvec.h | 29 +++++++++++++++++++++-------- 2 files changed, 26 insertions(+), 10 deletions(-) diff --git a/Documentation/block/biodoc.txt b/Documentation/block/biodoc.txt index ac18b488cb5e..c673d4285781 100644 --- a/Documentation/block/biodoc.txt +++ b/Documentation/block/biodoc.txt @@ -410,7 +410,7 @@ mapped to bio structures. 2.2 The bio struct The bio structure uses a vector representation pointing to an array of tuples -of <page, offset, len> to describe the i/o buffer, and has various other +of <pfn, offset, len> to describe the i/o buffer, and has various other fields describing i/o parameters and state that needs to be maintained for performing the i/o. @@ -418,11 +418,14 @@ Notice that this representation means that a bio has no virtual address mapping at all (unlike buffer heads). struct bio_vec { - struct page *bv_page; + unsigned long *bv_pfn; unsigned short bv_len; unsigned short bv_offset; }; +You should not access the bv_pfn fields directly but use helpers to get the +corresponding struct page as bv_pfn can encode more than page pfn value. + /* * main unit of I/O for the block layer and lower layers (ie drivers) */ diff --git a/include/linux/bvec.h b/include/linux/bvec.h index d701cd968f13..ac84ac66a333 100644 --- a/include/linux/bvec.h +++ b/include/linux/bvec.h @@ -29,7 +29,7 @@ * was unsigned short, but we might as well be ready for > 64kB I/O pages */ struct bio_vec { - struct page *bv_page; + unsigned long bv_pfn; unsigned int bv_len; unsigned int bv_offset; }; @@ -51,14 +51,19 @@ struct bvec_iter_all { unsigned done; }; +static inline unsigned long page_to_bvec_pfn(struct page *page) +{ + return page ? page_to_pfn(page) : -1UL; +} + static inline struct page *bvec_page(const struct bio_vec *bvec) { - return bvec->bv_page; + return bvec->bv_pfn == -1UL ? NULL : pfn_to_page(bvec->bv_pfn); } static inline void bvec_set_page(struct bio_vec *bvec, struct page *page) { - bvec->bv_page = page; + bvec->bv_pfn = page_to_bvec_pfn(page); } static inline struct page *bvec_nth_page(struct page *page, int idx) @@ -70,11 +75,15 @@ static inline struct page *bvec_nth_page(struct page *page, int idx) * various member access, note that bio_data should of course not be used * on highmem page vectors */ -#define BIO_VEC_INIT(p, l, o) {.bv_page = (p), .bv_len = (l), .bv_offset = (o)} +#define BIO_VEC_INIT(p, l, o) {.bv_pfn = page_to_bvec_pfn(p), \ + .bv_len = (l), .bv_offset = (o)} #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx]) /* multi-page (mp_bvec) helpers */ +#define mp_bvec_iter_pfn(bvec, iter) \ + ((__bvec_iter_bvec((bvec), (iter)))->bv_pfn) + #define mp_bvec_iter_page(bvec, iter) \ (bvec_page(__bvec_iter_bvec((bvec), (iter)))) @@ -90,7 +99,7 @@ static inline struct page *bvec_nth_page(struct page *page, int idx) #define mp_bvec_iter_bvec(bvec, iter) \ ((struct bio_vec) { \ - .bv_page = mp_bvec_iter_page((bvec), (iter)), \ + .bv_pfn = mp_bvec_iter_pfn((bvec), (iter)), \ .bv_len = mp_bvec_iter_len((bvec), (iter)), \ .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \ }) @@ -100,16 +109,20 @@ static inline struct page *bvec_nth_page(struct page *page, int idx) (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE) #define bvec_iter_len(bvec, iter) \ - min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \ + min_t(unsigned, mp_bvec_iter_len((bvec), (iter)), \ PAGE_SIZE - bvec_iter_offset((bvec), (iter))) #define bvec_iter_page(bvec, iter) \ - bvec_nth_page(mp_bvec_iter_page((bvec), (iter)), \ + bvec_nth_page(mp_bvec_iter_page((bvec), (iter)), \ mp_bvec_iter_page_idx((bvec), (iter))) +#define bvec_iter_pfn(bvec, iter) \ + (mp_bvec_iter_pfn((bvec), (iter)) + \ + mp_bvec_iter_page_idx((bvec), (iter))) + #define bvec_iter_bvec(bvec, iter) \ ((struct bio_vec) { \ - .bv_page = bvec_iter_page((bvec), (iter)), \ + .bv_pfn = bvec_iter_pfn((bvec), (iter)), \ .bv_len = bvec_iter_len((bvec), (iter)), \ .bv_offset = bvec_iter_offset((bvec), (iter)), \ }) -- 2.20.1
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