linux-kernel - [PATCH 32/60] block: implement sp version of bvec iterator helpers

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Message-Id: <1477728600-12938-33-git-send-email-tom.leiming@gmail.com>
Date:   Sat, 29 Oct 2016 16:08:31 +0800
From:   Ming Lei <tom.leiming@...il.com>
To:     Jens Axboe <axboe@...com>, linux-kernel@...r.kernel.org
Cc:     linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Christoph Hellwig <hch@...radead.org>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ming Lei <tom.leiming@...il.com>,
        Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH 32/60] block: implement sp version of bvec iterator helpers

This patch implements singlepage version of the following
3 helpers:
	- bvec_iter_offset_sp()
	- bvec_iter_len_sp()
	- bvec_iter_page_sp()

So that one multipage bvec can be splited to singlepage
bvec, and make users of current bvec iterator happy.

Signed-off-by: Ming Lei <tom.leiming@...il.com>
---
 include/linux/bvec.h | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index da984fa171bc..12c53a0eee52 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -22,6 +22,7 @@
 
 #include <linux/kernel.h>
 #include <linux/bug.h>
+#include <linux/mm.h>
 
 /*
  * What is multipage bvecs(segment)?
@@ -95,15 +96,25 @@ struct bvec_iter {
 #define bvec_iter_offset_mp(bvec, iter)				\
 	(__bvec_iter_bvec((bvec), (iter))->bv_offset + (iter).bi_bvec_done)
 
+#define bvec_iter_page_idx_mp(bvec, iter)			\
+	(bvec_iter_offset_mp((bvec), (iter)) / PAGE_SIZE)
+
 /*
  * <page, offset,length> of sp segment.
  *
  * This helpers will be implemented for building sp bvec in flight.
  *
  */
-#define bvec_iter_offset_sp(bvec, iter)	bvec_iter_offset_mp((bvec), (iter))
-#define bvec_iter_len_sp(bvec, iter)	bvec_iter_len_mp((bvec), (iter))
-#define bvec_iter_page_sp(bvec, iter)	bvec_iter_page_mp((bvec), (iter))
+#define bvec_iter_offset_sp(bvec, iter)					\
+	(bvec_iter_offset_mp((bvec), (iter)) % PAGE_SIZE)
+
+#define bvec_iter_len_sp(bvec, iter)					\
+	min_t(unsigned, bvec_iter_len_mp((bvec), (iter)),		\
+	    (PAGE_SIZE - (bvec_iter_offset_sp((bvec), (iter)))))
+
+#define bvec_iter_page_sp(bvec, iter)					\
+	nth_page(bvec_iter_page_mp((bvec), (iter)),			\
+		 bvec_iter_page_idx_mp((bvec), (iter)))
 
 /* current interfaces support sp style at default */
 #define bvec_iter_page(bvec, iter)	bvec_iter_page_sp((bvec), (iter))
-- 
2.7.4