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Date: Tue, 8 Aug 2017 16:45:18 +0800
From: Ming Lei <ming.lei@...hat.com>
To: Jens Axboe <axboe@...com>, Christoph Hellwig <hch@...radead.org>,
Huang Ying <ying.huang@...el.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Alexander Viro <viro@...iv.linux.org.uk>
Cc: linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
Ming Lei <ming.lei@...hat.com>
Subject: [PATCH v3 19/49] 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 <ming.lei@...hat.com>
---
include/linux/bvec.h | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index 1eaf7ca5cab3..d5f999a493de 100644
--- 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>
/*
* What is multipage bvecs(segment)?
@@ -98,14 +99,25 @@ 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 singlepage(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))
--
2.9.4
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