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Subject[PATCH 1/13] fs: convert core functions to zero_user_page
It's very common for file systems to need to zero part or all of a page, the
simplist way is just to use kmap_atomic() and memset(). There's actually a
library function in include/linux/highmem.h that does exactly that, but it's
confusingly named memclear_highpage_flush(), which is descriptive of *how*
it does the work rather than what the *purpose* is. So this patchset
renames the function to zero_user_page(), and calls it from the various
places that currently open code it.

This first patch introduces the new function call, and converts all the core
kernel callsites, both the open-coded ones and the old
memclear_highpage_flush() ones. Following this patch is a series of
conversions for each file system individually, per AKPM, and finally a patch
deprecating the old call. The diffstat below shows the entire patchset.

Compile tested in x86_64.

signed-off-by: Nate Diller <nate.diller@gmail.com>

---

drivers/block/loop.c | 6 ---
fs/affs/file.c | 6 ---
fs/buffer.c | 53 +++++--------------------------
fs/direct-io.c | 8 +---
fs/ecryptfs/mmap.c | 14 +-------
fs/ext3/inode.c | 12 +------
fs/ext4/inode.c | 12 +------
fs/ext4/writeback.c | 12 +------
fs/gfs2/bmap.c | 6 ---
fs/mpage.c | 11 +-----
fs/nfs/read.c | 10 ++---
fs/nfs/write.c | 2 -
fs/ntfs/aops.c | 26 ++-------------
fs/ntfs/file.c | 47 +++++----------------------
fs/ocfs2/aops.c | 5 --
fs/reiser4/plugin/file/cryptcompress.c | 19 +----------
fs/reiser4/plugin/file/file.c | 6 ---
fs/reiser4/plugin/item/ctail.c | 6 ---
fs/reiser4/plugin/item/extent_file_ops.c | 19 +++--------
fs/reiser4/plugin/item/tail.c | 8 +---
fs/reiserfs/file.c | 39 ++++++----------------
fs/reiserfs/inode.c | 13 +------
fs/xfs/linux-2.6/xfs_lrw.c | 2 -
include/linux/highmem.h | 7 +++-
mm/filemap_xip.c | 7 ----
mm/truncate.c | 2 -
26 files changed, 82 insertions(+), 276 deletions(-)

---

diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/drivers/block/loop.c linux-2.6.21-rc6-mm1-test/drivers/block/loop.c
--- linux-2.6.21-rc6-mm1/drivers/block/loop.c 2007-04-10 18:27:04.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/drivers/block/loop.c 2007-04-10 18:18:16.000000000 -0700
@@ -244,17 +244,13 @@ static int do_lo_send_aops(struct loop_d
transfer_result = lo_do_transfer(lo, WRITE, page, offset,
bvec->bv_page, bv_offs, size, IV);
if (unlikely(transfer_result)) {
- char *kaddr;
-
/*
* The transfer failed, but we still write the data to
* keep prepare/commit calls balanced.
*/
printk(KERN_ERR "loop: transfer error block %llu\n",
(unsigned long long)index);
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, size);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, offset, size);
}
flush_dcache_page(page);
ret = aops->commit_write(file, page, offset,
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/buffer.c linux-2.6.21-rc6-mm1-test/fs/buffer.c
--- linux-2.6.21-rc6-mm1/fs/buffer.c 2007-04-10 18:27:04.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/buffer.c 2007-04-10 18:18:16.000000000 -0700
@@ -1862,13 +1862,8 @@ static int __block_prepare_write(struct
if (block_start >= to)
break;
if (buffer_new(bh)) {
- void *kaddr;
-
clear_buffer_new(bh);
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr+block_start, 0, bh->b_size);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, block_start, bh->b_size);
set_buffer_uptodate(bh);
mark_buffer_dirty(bh);
}
@@ -1956,10 +1951,7 @@ int block_read_full_page(struct page *pa
SetPageError(page);
}
if (!buffer_mapped(bh)) {
- void *kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + i * blocksize, 0, blocksize);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, i * blocksize, blocksize);
if (!err)
set_buffer_uptodate(bh);
continue;
@@ -2102,7 +2094,6 @@ int cont_prepare_write(struct page *page
long status;
unsigned zerofrom;
unsigned blocksize = 1 << inode->i_blkbits;
- void *kaddr;

while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
status = -ENOMEM;
@@ -2124,10 +2115,7 @@ int cont_prepare_write(struct page *page
PAGE_CACHE_SIZE, get_block);
if (status)
goto out_unmap;
- kaddr = kmap_atomic(new_page, KM_USER0);
- memset(kaddr+zerofrom, 0, PAGE_CACHE_SIZE-zerofrom);
- flush_dcache_page(new_page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, zerofrom, PAGE_CACHE_SIZE-zerofrom);
generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
unlock_page(new_page);
page_cache_release(new_page);
@@ -2154,10 +2142,7 @@ int cont_prepare_write(struct page *page
if (status)
goto out1;
if (zerofrom < offset) {
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr+zerofrom, 0, offset-zerofrom);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, zerofrom, offset-zerofrom);
__block_commit_write(inode, page, zerofrom, offset);
}
return 0;
@@ -2356,10 +2341,7 @@ failed:
* Error recovery is pretty slack. Clear the page and mark it dirty
* so we'll later zero out any blocks which _were_ allocated.
*/
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr, 0, PAGE_CACHE_SIZE);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, 0, PAGE_CACHE_SIZE);
SetPageUptodate(page);
set_page_dirty(page);
return ret;
@@ -2398,7 +2380,6 @@ int nobh_writepage(struct page *page, ge
loff_t i_size = i_size_read(inode);
const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
- void *kaddr;
int ret;

/* Is the page fully inside i_size? */
@@ -2429,10 +2410,7 @@ int nobh_writepage(struct page *page, ge
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, offset, PAGE_CACHE_SIZE - offset);
out:
ret = mpage_writepage(page, get_block, wbc);
if (ret == -EAGAIN)
@@ -2453,7 +2431,6 @@ int nobh_truncate_page(struct address_sp
unsigned to;
struct page *page;
const struct address_space_operations *a_ops = mapping->a_ops;
- char *kaddr;
int ret = 0;

if ((offset & (blocksize - 1)) == 0)
@@ -2467,10 +2444,7 @@ int nobh_truncate_page(struct address_sp
to = (offset + blocksize) & ~(blocksize - 1);
ret = a_ops->prepare_write(NULL, page, offset, to);
if (ret == 0) {
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, offset, PAGE_CACHE_SIZE - offset);
/*
* It would be more correct to call aops->commit_write()
* here, but this is more efficient.
@@ -2496,7 +2470,6 @@ int block_truncate_page(struct address_s
struct inode *inode = mapping->host;
struct page *page;
struct buffer_head *bh;
- void *kaddr;
int err;

blocksize = 1 << inode->i_blkbits;
@@ -2550,11 +2523,7 @@ int block_truncate_page(struct address_s
goto unlock;
}

- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, length);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
-
+ zero_user_page(page, offset, length);
mark_buffer_dirty(bh);
err = 0;

@@ -2575,7 +2544,6 @@ int block_write_full_page(struct page *p
loff_t i_size = i_size_read(inode);
const pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
unsigned offset;
- void *kaddr;

/* Is the page fully inside i_size? */
if (page->index < end_index)
@@ -2601,10 +2569,7 @@ int block_write_full_page(struct page *p
* the page size, the remaining memory is zeroed when mapped, and
* writes to that region are not written out to the file."
*/
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, offset, PAGE_CACHE_SIZE - offset);
return __block_write_full_page(inode, page, get_block, wbc);
}

diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/direct-io.c linux-2.6.21-rc6-mm1-test/fs/direct-io.c
--- linux-2.6.21-rc6-mm1/fs/direct-io.c 2007-04-10 18:27:04.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/direct-io.c 2007-04-10 18:18:16.000000000 -0700
@@ -867,7 +867,6 @@ static int do_direct_IO(struct dio *dio)
do_holes:
/* Handle holes */
if (!buffer_mapped(map_bh)) {
- char *kaddr;
loff_t i_size_aligned;

/* AKPM: eargh, -ENOTBLK is a hack */
@@ -888,11 +887,8 @@ do_holes:
page_cache_release(page);
goto out;
}
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + (block_in_page << blkbits),
- 0, 1 << blkbits);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, block_in_page << blkbits,
+ 1 << blkbits);
dio->block_in_file++;
block_in_page++;
goto next_block;
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/mpage.c linux-2.6.21-rc6-mm1-test/fs/mpage.c
--- linux-2.6.21-rc6-mm1/fs/mpage.c 2007-04-10 18:27:04.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/mpage.c 2007-04-10 18:18:16.000000000 -0700
@@ -284,11 +284,8 @@ do_mpage_readpage(struct bio *bio, struc
}

if (first_hole != blocks_per_page) {
- char *kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + (first_hole << blkbits), 0,
+ zero_user_page(page, first_hole << blkbits,
PAGE_CACHE_SIZE - (first_hole << blkbits));
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
if (first_hole == 0) {
SetPageUptodate(page);
unlock_page(page);
@@ -586,14 +583,10 @@ page_is_mapped:
* written out to the file."
*/
unsigned offset = i_size & (PAGE_CACHE_SIZE - 1);
- char *kaddr;

if (page->index > end_index || !offset)
goto confused;
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, PAGE_CACHE_SIZE - offset);
- flush_dcache_page(page);
- kunmap_atomic(kaddr, KM_USER0);
+ zero_user_page(page, offset, PAGE_CACHE_SIZE - offset);
}

/*
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/include/linux/highmem.h linux-2.6.21-rc6-mm1-test/include/linux/highmem.h
--- linux-2.6.21-rc6-mm1/include/linux/highmem.h 2007-04-10 17:15:04.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/include/linux/highmem.h 2007-04-10 18:20:11.000000000 -0700
@@ -137,7 +137,7 @@ static inline void clear_highpage(struct
/*
* Same but also flushes aliased cache contents to RAM.
*/
-static inline void memclear_highpage_flush(struct page *page, unsigned int offset, unsigned int size)
+static inline void zero_user_page(struct page *page, unsigned int offset, unsigned int size)
{
void *kaddr;

@@ -149,6 +149,11 @@ static inline void memclear_highpage_flu
kunmap_atomic(kaddr, KM_USER0);
}

+static inline void memclear_highpage_flush(struct page *page, unsigned int offset, unsigned int size)
+{
+ return zero_user_page(page, offset, size);
+}
+
#ifndef __HAVE_ARCH_COPY_USER_HIGHPAGE

static inline void copy_user_highpage(struct page *to, struct page *from,
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/mm/filemap_xip.c linux-2.6.21-rc6-mm1-test/mm/filemap_xip.c
--- linux-2.6.21-rc6-mm1/mm/filemap_xip.c 2007-04-10 18:27:04.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/mm/filemap_xip.c 2007-04-10 18:18:16.000000000 -0700
@@ -440,7 +440,6 @@ xip_truncate_page(struct address_space *
unsigned blocksize;
unsigned length;
struct page *page;
- void *kaddr;

BUG_ON(!mapping->a_ops->get_xip_page);

@@ -464,11 +463,7 @@ xip_truncate_page(struct address_space *
else
return PTR_ERR(page);
}
- kaddr = kmap_atomic(page, KM_USER0);
- memset(kaddr + offset, 0, length);
- kunmap_atomic(kaddr, KM_USER0);
-
- flush_dcache_page(page);
+ zero_user_page(page, offset, length);
return 0;
}
EXPORT_SYMBOL_GPL(xip_truncate_page);
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/mm/truncate.c linux-2.6.21-rc6-mm1-test/mm/truncate.c
--- linux-2.6.21-rc6-mm1/mm/truncate.c 2007-04-10 18:27:04.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/mm/truncate.c 2007-04-10 18:18:16.000000000 -0700
@@ -46,7 +46,7 @@ void do_invalidatepage(struct page *page

static inline void truncate_partial_page(struct page *page, unsigned partial)
{
- memclear_highpage_flush(page, partial, PAGE_CACHE_SIZE-partial);
+ zero_user_page(page, partial, PAGE_CACHE_SIZE-partial);
if (PagePrivate(page))
do_invalidatepage(page, partial);
}
-
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