+++ /dev/null
-From 3d75ca0adef4280650c6690a0c4702a74a6f3c95 Mon Sep 17 00:00:00 2001
-From: Ming Lei <ming.lei@redhat.com>
-Date: Fri, 15 Feb 2019 19:13:10 +0800
-Subject: block: introduce multi-page bvec helpers
-
-From: Ming Lei <ming.lei@redhat.com>
-
-commit 3d75ca0adef4280650c6690a0c4702a74a6f3c95 upstream.
-
-This patch introduces helpers of 'mp_bvec_iter_*' for multi-page bvec
-support.
-
-The introduced helpers treate one bvec as real multi-page segment,
-which may include more than one pages.
-
-The existed helpers of bvec_iter_* are interfaces for supporting current
-bvec iterator which is thought as single-page by drivers, fs, dm and
-etc. These introduced helpers will build single-page bvec in flight, so
-this way won't break current bio/bvec users, which needn't any change.
-
-Follows some multi-page bvec background:
-
-- bvecs stored in bio->bi_io_vec is always multi-page style
-
-- bvec(struct bio_vec) represents one physically contiguous I/O
- buffer, now the buffer may include more than one page after
- multi-page bvec is supported, and all these pages represented
- by one bvec is physically contiguous. Before multi-page bvec
- support, at most one page is included in one bvec, we call it
- single-page bvec.
-
-- .bv_page of the bvec points to the 1st page in the multi-page bvec
-
-- .bv_offset of the bvec is the offset of the buffer in the bvec
-
-The effect on the current drivers/filesystem/dm/bcache/...:
-
-- almost everyone supposes that one bvec only includes one single
- page, so we keep the sp interface not changed, for example,
- bio_for_each_segment() still returns single-page bvec
-
-- bio_for_each_segment_all() will return single-page bvec too
-
-- during iterating, iterator variable(struct bvec_iter) is always
- updated in multi-page bvec style, and bvec_iter_advance() is kept
- not changed
-
-- returned(copied) single-page bvec is built in flight by bvec
- helpers from the stored multi-page bvec
-
-Reviewed-by: Christoph Hellwig <hch@lst.de>
-Reviewed-by: Omar Sandoval <osandov@fb.com>
-Signed-off-by: Ming Lei <ming.lei@redhat.com>
-Signed-off-by: Jens Axboe <axboe@kernel.dk>
-Cc: Zubin Mithra <zsm@chromium.org>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
----
- include/linux/bvec.h | 30 +++++++++++++++++++++++++++---
- 1 file changed, 27 insertions(+), 3 deletions(-)
-
---- a/include/linux/bvec.h
-+++ b/include/linux/bvec.h
-@@ -23,6 +23,7 @@
- #include <linux/kernel.h>
- #include <linux/bug.h>
- #include <linux/errno.h>
-+#include <linux/mm.h>
-
- /*
- * was unsigned short, but we might as well be ready for > 64kB I/O pages
-@@ -52,16 +53,39 @@ struct bvec_iter {
- */
- #define __bvec_iter_bvec(bvec, iter) (&(bvec)[(iter).bi_idx])
-
--#define bvec_iter_page(bvec, iter) \
-+/* multi-page (mp_bvec) helpers */
-+#define mp_bvec_iter_page(bvec, iter) \
- (__bvec_iter_bvec((bvec), (iter))->bv_page)
-
--#define bvec_iter_len(bvec, iter) \
-+#define mp_bvec_iter_len(bvec, iter) \
- min((iter).bi_size, \
- __bvec_iter_bvec((bvec), (iter))->bv_len - (iter).bi_bvec_done)
-
--#define bvec_iter_offset(bvec, iter) \
-+#define mp_bvec_iter_offset(bvec, iter) \
- (__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
-
-+#define mp_bvec_iter_page_idx(bvec, iter) \
-+ (mp_bvec_iter_offset((bvec), (iter)) / PAGE_SIZE)
-+
-+#define mp_bvec_iter_bvec(bvec, iter) \
-+((struct bio_vec) { \
-+ .bv_page = mp_bvec_iter_page((bvec), (iter)), \
-+ .bv_len = mp_bvec_iter_len((bvec), (iter)), \
-+ .bv_offset = mp_bvec_iter_offset((bvec), (iter)), \
-+})
-+
-+/* For building single-page bvec in flight */
-+ #define bvec_iter_offset(bvec, iter) \
-+ (mp_bvec_iter_offset((bvec), (iter)) % PAGE_SIZE)
-+
-+#define 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) \
-+ nth_page(mp_bvec_iter_page((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)), \