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Date: Mon, 09 Apr 2007 21:31:37 -0700
From: Nate Diller <nate.diller@...il.com>
To: Andrew Morton <akpm@...l.org>,
Alexander Viro <viro@...iv.linux.org.uk>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: [PATCH 2/2] fs: use simple_prepare_write to zero page data
It's common for file systems to need to zero data on either side of a write,
if a page is not Uptodate during prepare_write. It just so happens that
simple_prepare_write() in libfs.c does exactly that, so we can avoid
duplication and just call that function to zero page data.
Compile tested on x86_64.
signed-off-by: Nate Diller <nate.diller@...il.com>
---
cifs/file.c | 9 +--------
ext4/writeback.c | 17 +----------------
reiser4/plugin/item/extent_file_ops.c | 13 +++----------
3 files changed, 5 insertions(+), 34 deletions(-)
---
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/cifs/file.c linux-2.6.21-rc6-mm1-test/fs/cifs/file.c
--- linux-2.6.21-rc6-mm1/fs/cifs/file.c 2007-04-09 18:25:37.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/cifs/file.c 2007-04-09 18:23:16.000000000 -0700
@@ -1955,14 +1955,7 @@ static int cifs_prepare_write(struct fil
* We don't need to read data beyond the end of the file.
* zero it, and set the page uptodate
*/
- void *kaddr = kmap_atomic(page, KM_USER0);
-
- if (from)
- memset(kaddr, 0, from);
- if (to < PAGE_CACHE_SIZE)
- memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ simple_prepare_write(file, page, from, to);
SetPageUptodate(page);
} else if ((file->f_flags & O_ACCMODE) != O_WRONLY) {
/* might as well read a page, it is fast enough */
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/ext4/writeback.c linux-2.6.21-rc6-mm1-test/fs/ext4/writeback.c
--- linux-2.6.21-rc6-mm1/fs/ext4/writeback.c 2007-04-09 18:32:52.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/ext4/writeback.c 2007-04-09 18:23:16.000000000 -0700
@@ -819,21 +819,6 @@ int ext4_wb_writepages(struct address_sp
return 0;
}
-static void ext4_wb_clear_page(struct page *page, int from, int to)
-{
- void *kaddr;
-
- if (to < PAGE_CACHE_SIZE || from > 0) {
- kaddr = kmap_atomic(page, KM_USER0);
- if (PAGE_CACHE_SIZE > to)
- memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
- if (0 < from)
- memset(kaddr, 0, from);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- }
-}
-
int ext4_wb_prepare_write(struct file *file, struct page *page,
unsigned from, unsigned to)
{
@@ -863,7 +848,7 @@ int ext4_wb_prepare_write(struct file *f
/* this block isn't allocated yet, reserve space */
wb_debug("reserve space for new block\n");
page->private = 1;
- ext4_wb_clear_page(page, from, to);
+ simple_prepare_write(file, page, from, to);
ClearPageMappedToDisk(page);
} else {
/* block is already mapped, so no need to reserve */
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/reiser4/plugin/item/extent_file_ops.c linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/item/extent_file_ops.c
--- linux-2.6.21-rc6-mm1/fs/reiser4/plugin/item/extent_file_ops.c 2007-04-09 18:32:52.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/item/extent_file_ops.c 2007-04-09 18:31:34.000000000 -0700
@@ -1040,16 +1040,9 @@ ssize_t reiser4_write_extent(struct file
BUG_ON(get_current_context()->trans->atom != NULL);
lock_page(page);
- if (!PageUptodate(page) && to_page != PAGE_CACHE_SIZE) {
- void *kaddr;
-
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr, 0, page_off);
- memset(kaddr + page_off + to_page, 0,
- PAGE_CACHE_SIZE - (page_off + to_page));
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
- }
+ if (!PageUptodate(page) && to_page != PAGE_CACHE_SIZE)
+ simple_prepare_write(file, page, page_off,
+ page_off + to_page);
written = filemap_copy_from_user(page, page_off, buf, to_page);
flush_dcache_page(page);
-
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