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Date: Sun, 29 Apr 2007 23:14:40 -0700 (PDT)
From: Christoph Lameter <clameter@....com>
To: akpm@...ux-foundation.org
cc: Nate Diller <nate.diller@...il.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] zero_user_page uses in fs/buffer.c and fs/libfs.c
There are a couple of places where kmap_atomic is surrounding two
memory operations. Usually only one of them is performed. So it is
possible to also use zero_user_page there.
Cc: Nate Diller <nate.diller@...il.com>
Signed-off-by: Christoph Lameter <clameter@....com>
---
fs/buffer.c | 29 ++++++++++-------------------
fs/libfs.c | 12 ++++++------
2 files changed, 16 insertions(+), 25 deletions(-)
Index: linux-2.6.21-rc7-mm1/fs/buffer.c
===================================================================
--- linux-2.6.21-rc7-mm1.orig/fs/buffer.c 2007-04-25 00:20:35.000000000 -0700
+++ linux-2.6.21-rc7-mm1/fs/buffer.c 2007-04-25 00:24:05.000000000 -0700
@@ -1796,19 +1796,12 @@ static int __block_prepare_write(struct
set_buffer_uptodate(bh);
continue;
}
- if (block_end > to || block_start < from) {
- void *kaddr;
-
- kaddr = kmap_atomic(page, KM_USER0);
- if (block_end > to)
- memset(kaddr+to, 0,
- block_end-to);
- if (block_start < from)
- memset(kaddr+block_start,
- 0, from-block_start);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- }
+ if (block_end > to)
+ zero_user_page(page, to,
+ block_end - to, KM_USER0);
+ if (block_start < from)
+ zero_user_page(page, block_start,
+ from - block_start, KM_USER0);
continue;
}
}
@@ -2224,7 +2217,6 @@ int nobh_prepare_write(struct page *page
unsigned block_in_page;
unsigned block_start;
sector_t block_in_file;
- char *kaddr;
int nr_reads = 0;
int i;
int ret = 0;
@@ -2264,13 +2256,12 @@ int nobh_prepare_write(struct page *page
if (PageUptodate(page))
continue;
if (buffer_new(&map_bh) || !buffer_mapped(&map_bh)) {
- kaddr = kmap_atomic(page, KM_USER0);
if (block_start < from)
- memset(kaddr+block_start, 0, from-block_start);
+ zero_user_page(page, block_start,
+ from - block_start, KM_USER0);
if (block_end > to)
- memset(kaddr + to, 0, block_end - to);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, to,
+ block_end - to, KM_USER0);
continue;
}
if (buffer_uptodate(&map_bh))
Index: linux-2.6.21-rc7-mm1/fs/libfs.c
===================================================================
--- linux-2.6.21-rc7-mm1.orig/fs/libfs.c 2007-04-25 00:24:10.000000000 -0700
+++ linux-2.6.21-rc7-mm1/fs/libfs.c 2007-04-25 00:25:56.000000000 -0700
@@ -337,12 +337,12 @@ int simple_prepare_write(struct file *fi
unsigned from, unsigned to)
{
if (!PageUptodate(page)) {
- if (to - from != PAGE_CACHE_SIZE) {
- void *kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr, 0, from);
- memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ if (to - from != PAGE_CACHE_SIZE)
+ if (from)
+ zero_user_page(page, 0, from, KM_USER0);
+ if (to < PAGE_CACHE_SIZE)
+ zero_user_page(page, to,
+ PAGE_CACHE_SIZE - to, KM_USER0);
}
}
return 0;
-
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