[PATCH 05/33] readahead: refactor do_generic_mapping_read()

Wu Fengguang
2006-05-24T11:26:39Z

[-- Attachment #1: readahead-refactor-do_generic_mapping_read.patch --]
[-- Type: text/plain, Size: 2538 bytes --]

In do_generic_mapping_read(), release accessed pages some time later,
so that it can be passed to and used by the adaptive read-ahead code.

Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn>
---

mm/filemap.c | 18 ++++++++++++------
1 files changed, 12 insertions(+), 6 deletions(-)

--- linux-2.6.17-rc4-mm3.orig/mm/filemap.c
+++ linux-2.6.17-rc4-mm3/mm/filemap.c
@@ -813,10 +813,12 @@ void do_generic_mapping_read(struct addr
unsigned long prev_index;
loff_t isize;
struct page *cached_page;
+ struct page *prev_page;
int error;
struct file_ra_state ra = *_ra;

cached_page = NULL;
+ prev_page = NULL;
index = *ppos >> PAGE_CACHE_SHIFT;
next_index = index;
prev_index = ra.prev_page;
@@ -855,6 +857,11 @@ find_page:
handle_ra_miss(mapping, &ra, index);
goto no_cached_page;
}
+
+ if (prev_page)
+ page_cache_release(prev_page);
+ prev_page = page;
+
if (!PageUptodate(page))
goto page_not_up_to_date;
page_ok:
@@ -889,7 +896,6 @@ page_ok:
index += offset >> PAGE_CACHE_SHIFT;
offset &= ~PAGE_CACHE_MASK;

- page_cache_release(page);
if (ret == nr && desc->count)
continue;
goto out;
@@ -901,7 +907,6 @@ page_not_up_to_date:
/* Did it get unhashed before we got the lock? */
if (!page->mapping) {
unlock_page(page);
- page_cache_release(page);
continue;
}

@@ -931,7 +936,6 @@ readpage:
* invalidate_inode_pages got it
*/
unlock_page(page);
- page_cache_release(page);
goto find_page;
}
unlock_page(page);
@@ -952,7 +956,6 @@ readpage:
isize = i_size_read(inode);
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
if (unlikely(!isize || index > end_index)) {
- page_cache_release(page);
goto out;
}

@@ -961,7 +964,6 @@ readpage:
if (index == end_index) {
nr = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
if (nr <= offset) {
- page_cache_release(page);
goto out;
}
}
@@ -971,7 +973,6 @@ readpage:
readpage_error:
/* UHHUH! A synchronous read error occurred. Report it */
desc->error = error;
- page_cache_release(page);
goto out;

no_cached_page:
@@ -996,6 +997,9 @@ no_cached_page:
}
page = cached_page;
cached_page = NULL;
+ if (prev_page)
+ page_cache_release(prev_page);
+ prev_page = page;
goto readpage;
}

@@ -1005,6 +1009,8 @@ out:
*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
if (cached_page)
page_cache_release(cached_page);
+ if (prev_page)
+ page_cache_release(prev_page);
if (filp)
file_accessed(filp);
}

--