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 patch renames
the function to zero_page_data(), and calls it from the various places that
currently open code it.

Compile tested in x86_64.

signed-off-by: Nate Diller <[EMAIL PROTECTED]>

---

 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                           |   32 +++---------------
 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                  |    2 -
 mm/filemap_xip.c                         |    7 ----
 mm/truncate.c                            |    2 -
 26 files changed, 78 insertions(+), 281 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   2007-04-09 17:24:00.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/drivers/block/loop.c      2007-04-09 
18:18:23.000000000 -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_page_data(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/affs/file.c 
linux-2.6.21-rc6-mm1-test/fs/affs/file.c
--- linux-2.6.21-rc6-mm1/fs/affs/file.c 2007-04-09 17:23:48.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/affs/file.c    2007-04-09 18:18:23.000000000 
-0700
@@ -628,11 +628,7 @@ static int affs_prepare_write_ofs(struct
                        return err;
        }
        if (to < PAGE_CACHE_SIZE) {
-               char *kaddr = kmap_atomic(page, KM_USER0);
-
-               memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
-               flush_dcache_page(page);
-               kunmap_atomic(kaddr, KM_USER0);
+               zero_page_data(page, to, PAGE_CACHE_SIZE - to);
                if (size > offset + to) {
                        if (size < offset + PAGE_CACHE_SIZE)
                                tmp = size & ~PAGE_CACHE_MASK;
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    2007-04-09 17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/buffer.c       2007-04-09 18:18:23.000000000 
-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_page_data(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_page_data(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_page_data(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_page_data(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_page_data(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_page_data(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_page_data(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_page_data(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_page_data(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 2007-04-09 10:41:47.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/direct-io.c    2007-04-09 18:18:23.000000000 
-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_page_data(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/ecryptfs/mmap.c 
linux-2.6.21-rc6-mm1-test/fs/ecryptfs/mmap.c
--- linux-2.6.21-rc6-mm1/fs/ecryptfs/mmap.c     2007-04-09 17:24:03.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/fs/ecryptfs/mmap.c        2007-04-09 
18:19:34.000000000 -0700
@@ -364,18 +364,14 @@ static int fill_zeros_to_end_of_page(str
 {
        struct inode *inode = page->mapping->host;
        int end_byte_in_page;
-       char *page_virt;
 
        if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
                goto out;
        end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
        if (to > end_byte_in_page)
                end_byte_in_page = to;
-       page_virt = kmap_atomic(page, KM_USER0);
-       memset((page_virt + end_byte_in_page), 0,
-              (PAGE_CACHE_SIZE - end_byte_in_page));
-       kunmap_atomic(page_virt, KM_USER0);
-       flush_dcache_page(page);
+       zero_page_data(page, end_byte_in_page,
+               PAGE_CACHE_SIZE - end_byte_in_page);
 out:
        return 0;
 }
@@ -740,7 +736,6 @@ int write_zeros(struct file *file, pgoff
 {
        int rc = 0;
        struct page *tmp_page;
-       char *tmp_page_virt;
 
        tmp_page = ecryptfs_get1page(file, index);
        if (IS_ERR(tmp_page)) {
@@ -757,10 +752,7 @@ int write_zeros(struct file *file, pgoff
                page_cache_release(tmp_page);
                goto out;
        }
-       tmp_page_virt = kmap_atomic(tmp_page, KM_USER0);
-       memset(((char *)tmp_page_virt + start), 0, num_zeros);
-       kunmap_atomic(tmp_page_virt, KM_USER0);
-       flush_dcache_page(tmp_page);
+       zero_page_data(tmp_page, start, num_zeros);
        rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
        if (rc < 0) {
                ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/ext3/inode.c 
linux-2.6.21-rc6-mm1-test/fs/ext3/inode.c
--- linux-2.6.21-rc6-mm1/fs/ext3/inode.c        2007-04-09 17:24:03.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/fs/ext3/inode.c   2007-04-09 18:18:23.000000000 
-0700
@@ -1767,7 +1767,6 @@ static int ext3_block_truncate_page(hand
        struct inode *inode = mapping->host;
        struct buffer_head *bh;
        int err = 0;
-       void *kaddr;
 
        blocksize = inode->i_sb->s_blocksize;
        length = blocksize - (offset & (blocksize - 1));
@@ -1779,10 +1778,7 @@ static int ext3_block_truncate_page(hand
         */
        if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
             ext3_should_writeback_data(inode) && PageUptodate(page)) {
-               kaddr = kmap_atomic(page, KM_USER0);
-               memset(kaddr + offset, 0, length);
-               flush_dcache_page(page);
-               kunmap_atomic(kaddr, KM_USER0);
+               zero_page_data(page, offset, length);
                set_page_dirty(page);
                goto unlock;
        }
@@ -1835,11 +1831,7 @@ static int ext3_block_truncate_page(hand
                        goto unlock;
        }
 
-       kaddr = kmap_atomic(page, KM_USER0);
-       memset(kaddr + offset, 0, length);
-       flush_dcache_page(page);
-       kunmap_atomic(kaddr, KM_USER0);
-
+       zero_page_data(page, offset, length);
        BUFFER_TRACE(bh, "zeroed end of block");
 
        err = 0;
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/ext4/inode.c 
linux-2.6.21-rc6-mm1-test/fs/ext4/inode.c
--- linux-2.6.21-rc6-mm1/fs/ext4/inode.c        2007-04-09 17:24:03.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/fs/ext4/inode.c   2007-04-09 18:18:23.000000000 
-0700
@@ -1791,7 +1791,6 @@ int ext4_block_truncate_page(handle_t *h
        struct inode *inode = mapping->host;
        struct buffer_head *bh;
        int err = 0;
-       void *kaddr;
 
        if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) &&
                        test_opt(inode->i_sb, EXTENTS) &&
@@ -1808,10 +1807,7 @@ int ext4_block_truncate_page(handle_t *h
         */
        if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
             ext4_should_writeback_data(inode) && PageUptodate(page)) {
-               kaddr = kmap_atomic(page, KM_USER0);
-               memset(kaddr + offset, 0, length);
-               flush_dcache_page(page);
-               kunmap_atomic(kaddr, KM_USER0);
+               zero_page_data(page, offset, length);
                set_page_dirty(page);
                goto unlock;
        }
@@ -1864,11 +1860,7 @@ int ext4_block_truncate_page(handle_t *h
                        goto unlock;
        }
 
-       kaddr = kmap_atomic(page, KM_USER0);
-       memset(kaddr + offset, 0, length);
-       flush_dcache_page(page);
-       kunmap_atomic(kaddr, KM_USER0);
-
+       zero_page_data(page, offset, length);
        BUFFER_TRACE(bh, "zeroed end of block");
 
        err = 0;
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 17:24:03.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/fs/ext4/writeback.c       2007-04-09 
18:18:23.000000000 -0700
@@ -976,7 +976,6 @@ int ext4_wb_writepage(struct page *page,
        loff_t i_size = i_size_read(inode);
        pgoff_t end_index = i_size >> PAGE_CACHE_SHIFT;
        unsigned offset;
-       void *kaddr;
 
        wb_debug("writepage %lu from inode %lu\n", page->index, inode->i_ino);
 
@@ -1026,10 +1025,7 @@ int ext4_wb_writepage(struct page *page,
         * 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_page_data(page, offset, PAGE_CACHE_SIZE - offset);
        return ext4_wb_write_single_page(page, wbc);
 }
 
@@ -1080,7 +1076,6 @@ int ext4_wb_block_truncate_page(handle_t
        struct inode *inode = mapping->host;
        struct buffer_head bh, *bhw = &bh;
        unsigned blocksize, length;
-       void *kaddr;
        int err = 0;
 
        wb_debug("partial truncate from %lu on page %lu from inode %lu\n",
@@ -1119,10 +1114,7 @@ int ext4_wb_block_truncate_page(handle_t
                }
        }
 
-       kaddr = kmap_atomic(page, KM_USER0);
-       memset(kaddr + offset, 0, length);
-       flush_dcache_page(page);
-       kunmap_atomic(kaddr, KM_USER0);
+       zero_page_data(page, offset, length);
        SetPageUptodate(page);
        __set_page_dirty_nobuffers(page);
 
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/gfs2/bmap.c 
linux-2.6.21-rc6-mm1-test/fs/gfs2/bmap.c
--- linux-2.6.21-rc6-mm1/fs/gfs2/bmap.c 2007-04-09 17:23:48.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/gfs2/bmap.c    2007-04-09 18:18:23.000000000 
-0700
@@ -885,7 +885,6 @@ static int gfs2_block_truncate_page(stru
        unsigned blocksize, iblock, length, pos;
        struct buffer_head *bh;
        struct page *page;
-       void *kaddr;
        int err;
 
        page = grab_cache_page(mapping, index);
@@ -933,10 +932,7 @@ static int gfs2_block_truncate_page(stru
        if (sdp->sd_args.ar_data == GFS2_DATA_ORDERED || gfs2_is_jdata(ip))
                gfs2_trans_add_bh(ip->i_gl, bh, 0);
 
-       kaddr = kmap_atomic(page, KM_USER0);
-       memset(kaddr + offset, 0, length);
-       flush_dcache_page(page);
-       kunmap_atomic(kaddr, KM_USER0);
+       zero_page_data(page, offset, length);
 
 unlock:
        unlock_page(page);
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     2007-04-09 17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/mpage.c        2007-04-09 18:18:23.000000000 
-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_page_data(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_page_data(page, offset, PAGE_CACHE_SIZE - offset);
        }
 
        /*
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/nfs/read.c 
linux-2.6.21-rc6-mm1-test/fs/nfs/read.c
--- linux-2.6.21-rc6-mm1/fs/nfs/read.c  2007-04-09 17:23:48.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/nfs/read.c     2007-04-09 18:18:23.000000000 
-0700
@@ -79,7 +79,7 @@ void nfs_readdata_release(void *data)
 static
 int nfs_return_empty_page(struct page *page)
 {
-       memclear_highpage_flush(page, 0, PAGE_CACHE_SIZE);
+       zero_page_data(page, 0, PAGE_CACHE_SIZE);
        SetPageUptodate(page);
        unlock_page(page);
        return 0;
@@ -103,10 +103,10 @@ static void nfs_readpage_truncate_uninit
        pglen = PAGE_CACHE_SIZE - base;
        for (;;) {
                if (remainder <= pglen) {
-                       memclear_highpage_flush(*pages, base, remainder);
+                       zero_page_data(*pages, base, remainder);
                        break;
                }
-               memclear_highpage_flush(*pages, base, pglen);
+               zero_page_data(*pages, base, pglen);
                pages++;
                remainder -= pglen;
                pglen = PAGE_CACHE_SIZE;
@@ -130,7 +130,7 @@ static int nfs_readpage_async(struct nfs
                return PTR_ERR(new);
        }
        if (len < PAGE_CACHE_SIZE)
-               memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
+               zero_page_data(page, len, PAGE_CACHE_SIZE - len);
 
        nfs_list_add_request(new, &one_request);
        nfs_pagein_one(&one_request, inode);
@@ -561,7 +561,7 @@ readpage_async_filler(void *data, struct
                        return PTR_ERR(new);
        }
        if (len < PAGE_CACHE_SIZE)
-               memclear_highpage_flush(page, len, PAGE_CACHE_SIZE - len);
+               zero_page_data(page, len, PAGE_CACHE_SIZE - len);
        nfs_list_add_request(new, desc->head);
        return 0;
 }
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/nfs/write.c 
linux-2.6.21-rc6-mm1-test/fs/nfs/write.c
--- linux-2.6.21-rc6-mm1/fs/nfs/write.c 2007-04-09 17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/nfs/write.c    2007-04-09 18:18:23.000000000 
-0700
@@ -169,7 +169,7 @@ static void nfs_mark_uptodate(struct pag
        if (count != nfs_page_length(page))
                return;
        if (count != PAGE_CACHE_SIZE)
-               memclear_highpage_flush(page, count, PAGE_CACHE_SIZE - count);
+               zero_page_data(page, count, PAGE_CACHE_SIZE - count);
        SetPageUptodate(page);
 }
 
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/ntfs/aops.c 
linux-2.6.21-rc6-mm1-test/fs/ntfs/aops.c
--- linux-2.6.21-rc6-mm1/fs/ntfs/aops.c 2007-04-09 10:41:47.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/ntfs/aops.c    2007-04-09 18:18:23.000000000 
-0700
@@ -86,19 +86,15 @@ static void ntfs_end_buffer_async_read(s
                }
                /* Check for the current buffer head overflowing. */
                if (unlikely(file_ofs + bh->b_size > init_size)) {
-                       u8 *kaddr;
                        int ofs;
 
                        ofs = 0;
                        if (file_ofs < init_size)
                                ofs = init_size - file_ofs;
                        local_irq_save(flags);
-                       kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ);
-                       memset(kaddr + bh_offset(bh) + ofs, 0,
+                       zero_page_data(page, bh_offset(bh) + ofs,
                                        bh->b_size - ofs);
-                       kunmap_atomic(kaddr, KM_BIO_SRC_IRQ);
                        local_irq_restore(flags);
-                       flush_dcache_page(page);
                }
        } else {
                clear_buffer_uptodate(bh);
@@ -245,8 +241,7 @@ static int ntfs_read_block(struct page *
        rl = NULL;
        nr = i = 0;
        do {
-               u8 *kaddr;
-               int err;
+               int err = 0;
 
                if (unlikely(buffer_uptodate(bh)))
                        continue;
@@ -254,7 +249,6 @@ static int ntfs_read_block(struct page *
                        arr[nr++] = bh;
                        continue;
                }
-               err = 0;
                bh->b_bdev = vol->sb->s_bdev;
                /* Is the block within the allowed limits? */
                if (iblock < lblock) {
@@ -340,10 +334,7 @@ handle_hole:
                bh->b_blocknr = -1UL;
                clear_buffer_mapped(bh);
 handle_zblock:
-               kaddr = kmap_atomic(page, KM_USER0);
-               memset(kaddr + i * blocksize, 0, blocksize);
-               kunmap_atomic(kaddr, KM_USER0);
-               flush_dcache_page(page);
+               zero_page_data(page, i * blocksize, blocksize);
                if (likely(!err))
                        set_buffer_uptodate(bh);
        } while (i++, iblock++, (bh = bh->b_this_page) != head);
@@ -460,10 +451,7 @@ retry_readpage:
         * ok to ignore the compressed flag here.
         */
        if (unlikely(page->index > 0)) {
-               kaddr = kmap_atomic(page, KM_USER0);
-               memset(kaddr, 0, PAGE_CACHE_SIZE);
-               flush_dcache_page(page);
-               kunmap_atomic(kaddr, KM_USER0);
+               zero_page_data(page, 0, PAGE_CACHE_SIZE);
                goto done;
        }
        if (!NInoAttr(ni))
@@ -790,14 +778,9 @@ lock_retry_remap:
                 * uptodate so it can get discarded by the VM.
                 */
                if (err == -ENOENT || lcn == LCN_ENOENT) {
-                       u8 *kaddr;
-
                        bh->b_blocknr = -1;
                        clear_buffer_dirty(bh);
-                       kaddr = kmap_atomic(page, KM_USER0);
-                       memset(kaddr + bh_offset(bh), 0, blocksize);
-                       kunmap_atomic(kaddr, KM_USER0);
-                       flush_dcache_page(page);
+                       zero_page_data(page, bh_offset(bh), blocksize);
                        set_buffer_uptodate(bh);
                        err = 0;
                        continue;
@@ -1422,10 +1405,7 @@ retry_writepage:
                if (page->index >= (i_size >> PAGE_CACHE_SHIFT)) {
                        /* The page straddles i_size. */
                        unsigned int ofs = i_size & ~PAGE_CACHE_MASK;
-                       kaddr = kmap_atomic(page, KM_USER0);
-                       memset(kaddr + ofs, 0, PAGE_CACHE_SIZE - ofs);
-                       kunmap_atomic(kaddr, KM_USER0);
-                       flush_dcache_page(page);
+                       zero_page_data(page, ofs, PAGE_CACHE_SIZE - ofs);
                }
                /* Handle mst protected attributes. */
                if (NInoMstProtected(ni))
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/ntfs/file.c 
linux-2.6.21-rc6-mm1-test/fs/ntfs/file.c
--- linux-2.6.21-rc6-mm1/fs/ntfs/file.c 2007-04-09 17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/ntfs/file.c    2007-04-09 18:18:23.000000000 
-0700
@@ -606,11 +606,8 @@ do_next_page:
                                        ntfs_submit_bh_for_read(bh);
                                        *wait_bh++ = bh;
                                } else {
-                                       u8 *kaddr = kmap_atomic(page, KM_USER0);
-                                       memset(kaddr + bh_offset(bh), 0,
+                                       zero_page_data(page, bh_offset(bh),
                                                        blocksize);
-                                       kunmap_atomic(kaddr, KM_USER0);
-                                       flush_dcache_page(page);
                                        set_buffer_uptodate(bh);
                                }
                        }
@@ -685,12 +682,8 @@ map_buffer_cached:
                                                ntfs_submit_bh_for_read(bh);
                                                *wait_bh++ = bh;
                                        } else {
-                                               u8 *kaddr = kmap_atomic(page,
-                                                               KM_USER0);
-                                               memset(kaddr + bh_offset(bh),
-                                                               0, blocksize);
-                                               kunmap_atomic(kaddr, KM_USER0);
-                                               flush_dcache_page(page);
+                                               zero_page_data(page, 
bh_offset(bh),
+                                                               blocksize);
                                                set_buffer_uptodate(bh);
                                        }
                                }
@@ -708,11 +701,8 @@ map_buffer_cached:
                         */
                        if (bh_end <= pos || bh_pos >= end) {
                                if (!buffer_uptodate(bh)) {
-                                       u8 *kaddr = kmap_atomic(page, KM_USER0);
-                                       memset(kaddr + bh_offset(bh), 0,
+                                       zero_page_data(page, bh_offset(bh),
                                                        blocksize);
-                                       kunmap_atomic(kaddr, KM_USER0);
-                                       flush_dcache_page(page);
                                        set_buffer_uptodate(bh);
                                }
                                mark_buffer_dirty(bh);
@@ -751,10 +741,7 @@ map_buffer_cached:
                                if (!buffer_uptodate(bh))
                                        set_buffer_uptodate(bh);
                        } else if (!buffer_uptodate(bh)) {
-                               u8 *kaddr = kmap_atomic(page, KM_USER0);
-                               memset(kaddr + bh_offset(bh), 0, blocksize);
-                               kunmap_atomic(kaddr, KM_USER0);
-                               flush_dcache_page(page);
+                               zero_page_data(page, bh_offset(bh), blocksize);
                                set_buffer_uptodate(bh);
                        }
                        continue;
@@ -878,11 +865,8 @@ rl_not_mapped_enoent:
                                        if (!buffer_uptodate(bh))
                                                set_buffer_uptodate(bh);
                                } else if (!buffer_uptodate(bh)) {
-                                       u8 *kaddr = kmap_atomic(page, KM_USER0);
-                                       memset(kaddr + bh_offset(bh), 0,
+                                       zero_page_data(page, bh_offset(bh),
                                                        blocksize);
-                                       kunmap_atomic(kaddr, KM_USER0);
-                                       flush_dcache_page(page);
                                        set_buffer_uptodate(bh);
                                }
                                continue;
@@ -1137,16 +1121,12 @@ rl_not_mapped_enoent:
                         * to zero the overflowing region.
                         */
                        if (unlikely(bh_pos + blocksize > initialized_size)) {
-                               u8 *kaddr;
                                int ofs = 0;
 
                                if (likely(bh_pos < initialized_size))
                                        ofs = initialized_size - bh_pos;
-                               kaddr = kmap_atomic(page, KM_USER0);
-                               memset(kaddr + bh_offset(bh) + ofs, 0,
+                               zero_page_data(page, bh_offset(bh) + ofs,
                                                blocksize - ofs);
-                               kunmap_atomic(kaddr, KM_USER0);
-                               flush_dcache_page(page);
                        }
                } else /* if (unlikely(!buffer_uptodate(bh))) */
                        err = -EIO;
@@ -1286,11 +1266,8 @@ rl_not_mapped_enoent:
                                if (PageUptodate(page))
                                        set_buffer_uptodate(bh);
                                else {
-                                       u8 *kaddr = kmap_atomic(page, KM_USER0);
-                                       memset(kaddr + bh_offset(bh), 0,
+                                       zero_page_data(page, bh_offset(bh),
                                                        blocksize);
-                                       kunmap_atomic(kaddr, KM_USER0);
-                                       flush_dcache_page(page);
                                        set_buffer_uptodate(bh);
                                }
                        }
@@ -1350,9 +1327,7 @@ err_out:
                len = PAGE_CACHE_SIZE;
                if (len > bytes)
                        len = bytes;
-               kaddr = kmap_atomic(*pages, KM_USER0);
-               memset(kaddr, 0, len);
-               kunmap_atomic(kaddr, KM_USER0);
+               zero_page_data(*pages, 0, len);
        }
        goto out;
 }
@@ -1473,9 +1448,7 @@ err_out:
                len = PAGE_CACHE_SIZE;
                if (len > bytes)
                        len = bytes;
-               kaddr = kmap_atomic(*pages, KM_USER0);
-               memset(kaddr, 0, len);
-               kunmap_atomic(kaddr, KM_USER0);
+               zero_page_data(*pages, 0, len);
        }
        goto out;
 }
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/ocfs2/aops.c 
linux-2.6.21-rc6-mm1-test/fs/ocfs2/aops.c
--- linux-2.6.21-rc6-mm1/fs/ocfs2/aops.c        2007-04-09 17:24:03.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/fs/ocfs2/aops.c   2007-04-09 18:18:23.000000000 
-0700
@@ -234,10 +234,7 @@ static int ocfs2_readpage(struct file *f
         * XXX sys_readahead() seems to get that wrong?
         */
        if (start >= i_size_read(inode)) {
-               char *addr = kmap(page);
-               memset(addr, 0, PAGE_SIZE);
-               flush_dcache_page(page);
-               kunmap(page);
+               zero_page_data(page, 0, PAGE_SIZE);
                SetPageUptodate(page);
                ret = 0;
                goto out_alloc;
diff -urpN -X dontdiff 
linux-2.6.21-rc6-mm1/fs/reiser4/plugin/file/cryptcompress.c 
linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/file/cryptcompress.c
--- linux-2.6.21-rc6-mm1/fs/reiser4/plugin/file/cryptcompress.c 2007-04-09 
17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/file/cryptcompress.c    
2007-04-09 18:18:23.000000000 -0700
@@ -1897,7 +1897,6 @@ static int
 write_hole(struct inode *inode, reiser4_cluster_t * clust, loff_t file_off,
           loff_t to_file)
 {
-       char *data;
        int result = 0;
        unsigned cl_off, cl_count = 0;
        unsigned to_pg, pg_off;
@@ -1934,10 +1933,7 @@ write_hole(struct inode *inode, reiser4_
 
                to_pg = min_count(PAGE_CACHE_SIZE - pg_off, cl_count);
                lock_page(page);
-               data = kmap_atomic(page, KM_USER0);
-               memset(data + pg_off, 0, to_pg);
-               flush_dcache_page(page);
-               kunmap_atomic(data, KM_USER0);
+               zero_page_data(page, pg_off, to_pg);
                SetPageUptodate(page);
                unlock_page(page);
 
@@ -2167,7 +2163,6 @@ read_some_cluster_pages(struct inode *in
 
                if (clust->nr_pages) {
                        int off;
-                       char *data;
                        struct page * pg;
                        assert("edward-1419", clust->pages != NULL);
                        pg = clust->pages[clust->nr_pages - 1];
@@ -2175,10 +2170,7 @@ read_some_cluster_pages(struct inode *in
                        off = off_to_pgoff(win->off+win->count+win->delta);
                        if (off) {
                                lock_page(pg);
-                               data = kmap_atomic(pg, KM_USER0);
-                               memset(data + off, 0, PAGE_CACHE_SIZE - off);
-                               flush_dcache_page(pg);
-                               kunmap_atomic(data, KM_USER0);
+                               zero_page_data(pg, off, PAGE_CACHE_SIZE - off);
                                unlock_page(pg);
                        }
                }
@@ -2217,20 +2209,15 @@ read_some_cluster_pages(struct inode *in
                    (count_to_nrpages(inode->i_size) <= pg->index)) {
                        /* .. and appended,
                           so set zeroes to the rest */
-                       char *data;
                        int offset;
                        lock_page(pg);
-                       data = kmap_atomic(pg, KM_USER0);
-
                        assert("edward-1260",
                               count_to_nrpages(win->off + win->count +
                                                win->delta) - 1 == i);
 
                        offset =
                            off_to_pgoff(win->off + win->count + win->delta);
-                       memset(data + offset, 0, PAGE_CACHE_SIZE - offset);
-                       flush_dcache_page(pg);
-                       kunmap_atomic(data, KM_USER0);
+                       zero_page_data(pg, offset, PAGE_CACHE_SIZE - offset);
                        unlock_page(pg);
                        /* still not uptodate */
                        break;
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/reiser4/plugin/file/file.c 
linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/file/file.c
--- linux-2.6.21-rc6-mm1/fs/reiser4/plugin/file/file.c  2007-04-09 
17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/file/file.c     2007-04-09 
18:18:23.000000000 -0700
@@ -433,7 +433,6 @@ static int shorten_file(struct inode *in
        struct page *page;
        int padd_from;
        unsigned long index;
-       char *kaddr;
        unix_file_info_t *uf_info;
 
        /*
@@ -523,10 +522,7 @@ static int shorten_file(struct inode *in
 
        lock_page(page);
        assert("vs-1066", PageLocked(page));
-       kaddr = kmap_atomic(page, KM_USER0);
-       memset(kaddr + padd_from, 0, PAGE_CACHE_SIZE - padd_from);
-       flush_dcache_page(page);
-       kunmap_atomic(kaddr, KM_USER0);
+       zero_page_data(page, padd_from, PAGE_CACHE_SIZE - padd_from);
        unlock_page(page);
        page_cache_release(page);
        /* the below does up(sbinfo->delete_mutex). Do not get confused */
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/reiser4/plugin/item/ctail.c 
linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/item/ctail.c
--- linux-2.6.21-rc6-mm1/fs/reiser4/plugin/item/ctail.c 2007-04-09 
17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/item/ctail.c    2007-04-09 
18:18:23.000000000 -0700
@@ -627,11 +627,7 @@ int do_readpage_ctail(struct inode * ino
 #endif
        case FAKE_DISK_CLUSTER:
                /* fill the page by zeroes */
-               data = kmap_atomic(page, KM_USER0);
-
-               memset(data, 0, PAGE_CACHE_SIZE);
-               flush_dcache_page(page);
-               kunmap_atomic(data, KM_USER0);
+               zero_page_data(page, 0, PAGE_CACHE_SIZE);
                SetPageUptodate(page);
                break;
        case PREP_DISK_CLUSTER:
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 17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/item/extent_file_ops.c  
2007-04-09 18:18:23.000000000 -0700
@@ -1090,17 +1090,6 @@ ssize_t reiser4_write_extent(struct file
        return (count - left) ? (count - left) : -EFAULT;
 }
 
-static inline void zero_page(struct page *page)
-{
-       char *kaddr = kmap_atomic(page, KM_USER0);
-
-       memset(kaddr, 0, PAGE_CACHE_SIZE);
-       flush_dcache_page(page);
-       kunmap_atomic(kaddr, KM_USER0);
-       SetPageUptodate(page);
-       unlock_page(page);
-}
-
 int reiser4_do_readpage_extent(reiser4_extent * ext, reiser4_block_nr pos,
                               struct page *page)
 {
@@ -1122,7 +1111,9 @@ int reiser4_do_readpage_extent(reiser4_e
                 */
                j = jfind(mapping, index);
                if (j == NULL) {
-                       zero_page(page);
+                       zero_page_data(page, 0, PAGE_CACHE_SIZE);
+                       SetPageUptodate(page);
+                       unlock_page(page);
                        return 0;
                }
                spin_lock_jnode(j);
@@ -1135,7 +1126,9 @@ int reiser4_do_readpage_extent(reiser4_e
                block = *jnode_get_io_block(j);
                spin_unlock_jnode(j);
                if (block == 0) {
-                       zero_page(page);
+                       zero_page_data(page, 0, PAGE_CACHE_SIZE);
+                       SetPageUptodate(page);
+                       unlock_page(page);
                        jput(j);
                        return 0;
                }
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/reiser4/plugin/item/tail.c 
linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/item/tail.c
--- linux-2.6.21-rc6-mm1/fs/reiser4/plugin/item/tail.c  2007-04-09 
17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/reiser4/plugin/item/tail.c     2007-04-09 
18:18:23.000000000 -0700
@@ -391,12 +391,8 @@ static int do_readpage_tail(uf_coord_t *
        }
 
  done:
-       if (mapped != PAGE_CACHE_SIZE) {
-               pagedata = kmap_atomic(page, KM_USER0);
-               memset(pagedata + mapped, 0, PAGE_CACHE_SIZE - mapped);
-               flush_dcache_page(page);
-               kunmap_atomic(pagedata, KM_USER0);
-       }
+       if (mapped != PAGE_CACHE_SIZE)
+               zero_page_data(page, mapped, PAGE_CACHE_SIZE - mapped);
        SetPageUptodate(page);
  out_unlock_page:
        unlock_page(page);
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/reiserfs/file.c 
linux-2.6.21-rc6-mm1-test/fs/reiserfs/file.c
--- linux-2.6.21-rc6-mm1/fs/reiserfs/file.c     2007-04-09 17:24:03.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/fs/reiserfs/file.c        2007-04-09 
18:18:23.000000000 -0700
@@ -1059,20 +1059,12 @@ static int reiserfs_prepare_file_region_
           maping blocks, since there is none, so we just zero out remaining
           parts of first and last pages in write area (if needed) */
        if ((pos & ~((loff_t) PAGE_CACHE_SIZE - 1)) > inode->i_size) {
-               if (from != 0) {        /* First page needs to be partially 
zeroed */
-                       char *kaddr = kmap_atomic(prepared_pages[0], KM_USER0);
-                       memset(kaddr, 0, from);
-                       kunmap_atomic(kaddr, KM_USER0);
-                       flush_dcache_page(prepared_pages[0]);
-               }
-               if (to != PAGE_CACHE_SIZE) {    /* Last page needs to be 
partially zeroed */
-                       char *kaddr =
-                           kmap_atomic(prepared_pages[num_pages - 1],
-                                       KM_USER0);
-                       memset(kaddr + to, 0, PAGE_CACHE_SIZE - to);
-                       kunmap_atomic(kaddr, KM_USER0);
-                       flush_dcache_page(prepared_pages[num_pages - 1]);
-               }
+               if (from != 0)          /* First page needs to be partially 
zeroed */
+                       zero_page_data(prepared_pages[0], 0, from);
+
+               if (to != PAGE_CACHE_SIZE)      /* Last page needs to be 
partially zeroed */
+                       zero_page_data(prepared_pages[num_pages-1], to,
+                                       PAGE_CACHE_SIZE - to);
 
                /* Since all blocks are new - use already calculated value */
                return blocks;
@@ -1199,13 +1191,9 @@ static int reiserfs_prepare_file_region_
                                        ll_rw_block(READ, 1, &bh);
                                        *wait_bh++ = bh;
                                } else {        /* Not mapped, zero it */
-                                       char *kaddr =
-                                           kmap_atomic(prepared_pages[0],
-                                                       KM_USER0);
-                                       memset(kaddr + block_start, 0,
-                                              from - block_start);
-                                       kunmap_atomic(kaddr, KM_USER0);
-                                       flush_dcache_page(prepared_pages[0]);
+                                       zero_page_data(prepared_pages[0],
+                                                      block_start,
+                                                      from - block_start);
                                        set_buffer_uptodate(bh);
                                }
                        }
@@ -1237,13 +1225,8 @@ static int reiserfs_prepare_file_region_
                                        ll_rw_block(READ, 1, &bh);
                                        *wait_bh++ = bh;
                                } else {        /* Not mapped, zero it */
-                                       char *kaddr =
-                                           kmap_atomic(prepared_pages
-                                                       [num_pages - 1],
-                                                       KM_USER0);
-                                       memset(kaddr + to, 0, block_end - to);
-                                       kunmap_atomic(kaddr, KM_USER0);
-                                       
flush_dcache_page(prepared_pages[num_pages - 1]);
+                                       
zero_page_data(prepared_pages[num_pages-1],
+                                                       to, block_end - to);
                                        set_buffer_uptodate(bh);
                                }
                        }
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/reiserfs/inode.c 
linux-2.6.21-rc6-mm1-test/fs/reiserfs/inode.c
--- linux-2.6.21-rc6-mm1/fs/reiserfs/inode.c    2007-04-09 10:41:47.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/fs/reiserfs/inode.c       2007-04-09 
18:18:23.000000000 -0700
@@ -2148,13 +2148,8 @@ int reiserfs_truncate_file(struct inode 
                length = offset & (blocksize - 1);
                /* if we are not on a block boundary */
                if (length) {
-                       char *kaddr;
-
                        length = blocksize - length;
-                       kaddr = kmap_atomic(page, KM_USER0);
-                       memset(kaddr + offset, 0, length);
-                       flush_dcache_page(page);
-                       kunmap_atomic(kaddr, KM_USER0);
+                       zero_page_data(page, offset, length);
                        if (buffer_mapped(bh) && bh->b_blocknr != 0) {
                                mark_buffer_dirty(bh);
                        }
@@ -2370,7 +2365,6 @@ static int reiserfs_write_full_page(stru
         ** last byte in the file
         */
        if (page->index >= end_index) {
-               char *kaddr;
                unsigned last_offset;
 
                last_offset = inode->i_size & (PAGE_CACHE_SIZE - 1);
@@ -2379,10 +2373,7 @@ static int reiserfs_write_full_page(stru
                        unlock_page(page);
                        return 0;
                }
-               kaddr = kmap_atomic(page, KM_USER0);
-               memset(kaddr + last_offset, 0, PAGE_CACHE_SIZE - last_offset);
-               flush_dcache_page(page);
-               kunmap_atomic(kaddr, KM_USER0);
+               zero_page_data(page, last_offset, PAGE_CACHE_SIZE - 
last_offset);
        }
        bh = head;
        block = page->index << (PAGE_CACHE_SHIFT - s->s_blocksize_bits);
diff -urpN -X dontdiff linux-2.6.21-rc6-mm1/fs/xfs/linux-2.6/xfs_lrw.c 
linux-2.6.21-rc6-mm1-test/fs/xfs/linux-2.6/xfs_lrw.c
--- linux-2.6.21-rc6-mm1/fs/xfs/linux-2.6/xfs_lrw.c     2007-04-09 
17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/fs/xfs/linux-2.6/xfs_lrw.c        2007-04-09 
18:18:23.000000000 -0700
@@ -159,7 +159,7 @@ xfs_iozero(
                if (status)
                        goto unlock;
 
-               memclear_highpage_flush(page, offset, bytes);
+               zero_page_data(page, offset, bytes);
 
                status = mapping->a_ops->commit_write(NULL, page, offset,
                                                        offset + bytes);
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        2007-04-09 
17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/include/linux/highmem.h   2007-04-09 
18:18:23.000000000 -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_page_data(struct page *page, unsigned int offset, 
unsigned int size)
 {
        void *kaddr;
 
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       2007-04-09 17:24:03.000000000 
-0700
+++ linux-2.6.21-rc6-mm1-test/mm/filemap_xip.c  2007-04-09 18:18:23.000000000 
-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_page_data(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  2007-04-09 17:24:03.000000000 -0700
+++ linux-2.6.21-rc6-mm1-test/mm/truncate.c     2007-04-09 18:18:23.000000000 
-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_page_data(page, partial, PAGE_CACHE_SIZE-partial);
        if (PagePrivate(page))
                do_invalidatepage(page, partial);
 }
-
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