We may now have to zero and flush higher order pages. Implement
clear_mapping_page and flush_mapping_page to do that job. Replace
the flushing and clearing at some key locations for the pagecache.

Signed-off-by: Christoph Lameter <[EMAIL PROTECTED]>
---
 fs/libfs.c              |    4 ++--
 include/linux/highmem.h |   31 +++++++++++++++++++++++++++++--
 mm/filemap.c            |    4 ++--
 mm/filemap_xip.c        |    4 ++--
 4 files changed, 35 insertions(+), 8 deletions(-)

Index: linux-2.6/fs/libfs.c
===================================================================
--- linux-2.6.orig/fs/libfs.c   2007-08-27 20:51:55.000000000 -0700
+++ linux-2.6/fs/libfs.c        2007-08-27 21:08:04.000000000 -0700
@@ -330,8 +330,8 @@ int simple_rename(struct inode *old_dir,
 
 int simple_readpage(struct file *file, struct page *page)
 {
-       clear_highpage(page);
-       flush_dcache_page(page);
+       clear_mapping_page(page);
+       flush_mapping_page(page);
        SetPageUptodate(page);
        unlock_page(page);
        return 0;
Index: linux-2.6/include/linux/highmem.h
===================================================================
--- linux-2.6.orig/include/linux/highmem.h      2007-08-27 19:22:17.000000000 
-0700
+++ linux-2.6/include/linux/highmem.h   2007-08-27 21:08:04.000000000 -0700
@@ -124,14 +124,41 @@ static inline void clear_highpage(struct
        kunmap_atomic(kaddr, KM_USER0);
 }
 
+/*
+ * Clear a higher order page
+ */
+static inline void clear_mapping_page(struct page *page)
+{
+       int nr_pages = compound_pages(page);
+       int i;
+
+       for (i = 0; i < nr_pages; i++)
+               clear_highpage(page + i);
+}
+
+/*
+ * Primitive support for flushing higher order pages.
+ *
+ * A bit stupid: On many platforms flushing the first page
+ * will flush any TLB starting there
+ */
+static inline void flush_mapping_page(struct page *page)
+{
+       int nr_pages = compound_pages(page);
+       int i;
+
+       for (i = 0; i < nr_pages; i++)
+               flush_dcache_page(page + i);
+}
+
 static inline void zero_user_segments(struct page *page,
        unsigned start1, unsigned end1,
        unsigned start2, unsigned end2)
 {
        void *kaddr = kmap_atomic(page, KM_USER0);
 
-       BUG_ON(end1 > PAGE_SIZE ||
-               end2 > PAGE_SIZE);
+       BUG_ON(end1 > compound_size(page) ||
+               end2 > compound_size(page));
 
        if (end1 > start1)
                memset(kaddr + start1, 0, end1 - start1);
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c 2007-08-27 19:31:13.000000000 -0700
+++ linux-2.6/mm/filemap.c      2007-08-27 21:08:04.000000000 -0700
@@ -941,7 +941,7 @@ page_ok:
                 * before reading the page on the kernel side.
                 */
                if (mapping_writably_mapped(mapping))
-                       flush_dcache_page(page);
+                       flush_mapping_page(page);
 
                /*
                 * When a sequential read accesses a page several times,
@@ -1932,7 +1932,7 @@ generic_file_buffered_write(struct kiocb
                else
                        copied = filemap_copy_from_user_iovec(page, offset,
                                                cur_iov, iov_base, bytes);
-               flush_dcache_page(page);
+               flush_mapping_page(page);
                status = a_ops->commit_write(file, page, offset, offset+bytes);
                if (status == AOP_TRUNCATED_PAGE) {
                        page_cache_release(page);
Index: linux-2.6/mm/filemap_xip.c
===================================================================
--- linux-2.6.orig/mm/filemap_xip.c     2007-08-27 20:51:40.000000000 -0700
+++ linux-2.6/mm/filemap_xip.c  2007-08-27 21:08:04.000000000 -0700
@@ -104,7 +104,7 @@ do_xip_mapping_read(struct address_space
                 * before reading the page on the kernel side.
                 */
                if (mapping_writably_mapped(mapping))
-                       flush_dcache_page(page);
+                       flush_mapping_page(page);
 
                /*
                 * Ok, we have the page, so now we can copy it to user space...
@@ -320,7 +320,7 @@ __xip_file_write(struct file *filp, cons
                }
 
                copied = filemap_copy_from_user(page, offset, buf, bytes);
-               flush_dcache_page(page);
+               flush_mapping_page(page);
                if (likely(copied > 0)) {
                        status = copied;
 

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