the modifications on mm/filemap.c
Signed-Off-By: Dirk Gerdes <[email protected]>
---
--- linux-2.6-block_clean/mm/filemap.c 2005-11-30 16:13:25.000000000
+0100
+++ linux-2.6-block-pagecache-clean/mm/filemap.c 2005-11-30 17:15:50.000000000 +0100
@@ -702,6 +702,55 @@ grab_cache_page_nowait(struct address_sp
EXPORT_SYMBOL(grab_cache_page_nowait);
+
+
+
+void make_page_not_uptodate(struct page *page)
+{
+ struct buffer_head *bh, *first;
+ //printk("make_page_not_uptodate_called\n");
+ lock_page(page);
+ if(!PageDirty(page)){
+ ClearPageUptodate(page);
+ if (page_has_buffers(page)){
+ bh = page_buffers(page);
+ first = bh;
+ do{
+ lock_buffer(bh);
+ if(!buffer_dirty(bh)){
+ clear_buffer_uptodate(bh);
+ }
+ unlock_buffer(bh);
+
+ bh=bh->b_this_page;
+
+ }while(bh != first);
+ }
+ }
+ unlock_page(page);
+ release_pages(&page, 1, 0);
+}
+
+int pagecache = 1; // bool pagecache on / off
+ // 1 : on
+ // 2 : off
+EXPORT_SYMBOL(pagecache);
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
/*
* This is a generic file read routine, and uses the
* mapping->a_ops->readpage() function for the actual low-level
@@ -729,6 +778,7 @@ void do_generic_mapping_read(struct addr
unsigned long prev_index;
loff_t isize;
struct page *cached_page;
+ struct page *foundpage = NULL;
int error;
struct file_ra_state ra = *_ra;
@@ -744,6 +794,17 @@ void do_generic_mapping_read(struct addr
goto out;
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
+
+/**
+if the needed page is in Page Cache its PageUptodate-Bit is cleared, so it have to be read again
+*/
+ if (pagecache == 0){
+ foundpage = find_get_page(mapping,index);
+ if (foundpage != NULL){
+ make_page_not_uptodate(foundpage);
+ }
+ }
+
for (;;) {
struct page *page;
unsigned long nr, ret;
@@ -761,9 +822,12 @@ void do_generic_mapping_read(struct addr
nr = nr - offset;
cond_resched();
- if (index == next_index)
- next_index = page_cache_readahead(mapping, &ra, filp,
- index, last_index - index);
+
+/**page_cache_readahead should only be used, if pagecache is activated */
+ if (pagecache){
+ if (index == next_index)
+ next_index = page_cache_readahead(mapping, &ra, filp,index, last_index - index);
+ }
find_page:
page = find_get_page(mapping, index);
@@ -806,8 +870,15 @@ page_ok:
offset &= ~PAGE_CACHE_MASK;
page_cache_release(page);
- if (ret == nr && desc->count)
+ if (ret == nr && desc->count){
+ if (pagecache == 0){
+ foundpage = find_get_page(mapping,index);
+ if (foundpage != NULL){
+ make_page_not_uptodate(foundpage);
+ }
+ }
continue;
+ }
goto out;
page_not_up_to_date: