[RFC 2/7] Move checks from pageout() to shrink_page_list

From: Christoph Lameter
Date: Mon Aug 20 2007 - 17:54:42 EST


This is necessary because we soon will do other things than calling
pageout() from shrink_page_list().

Signed-off-by: Christoph Lameter <clameter@xxxxxxx>

---
mm/vmscan.c | 90 ++++++++++++++++++++++++++++++------------------------------
1 file changed, 45 insertions(+), 45 deletions(-)

Index: linux-2.6/mm/vmscan.c
===================================================================
--- linux-2.6.orig/mm/vmscan.c 2007-08-19 21:39:55.000000000 -0700
+++ linux-2.6/mm/vmscan.c 2007-08-19 21:47:56.000000000 -0700
@@ -273,8 +273,6 @@ static void handle_write_error(struct ad

/* possible outcome of pageout() */
typedef enum {
- /* failed to write page out, page is locked */
- PAGE_KEEP,
/* move page to the active list, page is locked */
PAGE_ACTIVATE,
/* page has been sent to the disk successfully, page is unlocked */
@@ -289,44 +287,6 @@ typedef enum {
*/
static pageout_t pageout(struct page *page, struct address_space *mapping)
{
- /*
- * If the page is dirty, only perform writeback if that write
- * will be non-blocking. To prevent this allocation from being
- * stalled by pagecache activity. But note that there may be
- * stalls if we need to run get_block(). We could test
- * PagePrivate for that.
- *
- * If this process is currently in generic_file_write() against
- * this page's queue, we can perform writeback even if that
- * will block.
- *
- * If the page is swapcache, write it back even if that would
- * block, for some throttling. This happens by accident, because
- * swap_backing_dev_info is bust: it doesn't reflect the
- * congestion state of the swapdevs. Easy to fix, if needed.
- * See swapfile.c:page_queue_congested().
- */
- if (!is_page_cache_freeable(page))
- return PAGE_KEEP;
- if (!mapping) {
- /*
- * Some data journaling orphaned pages can have
- * page->mapping == NULL while being dirty with clean buffers.
- */
- if (PagePrivate(page)) {
- if (try_to_free_buffers(page)) {
- ClearPageDirty(page);
- printk("%s: orphaned page\n", __FUNCTION__);
- return PAGE_CLEAN;
- }
- }
- return PAGE_KEEP;
- }
- if (mapping->a_ops->writepage == NULL)
- return PAGE_ACTIVATE;
- if (!may_write_to_queue(mapping->backing_dev_info))
- return PAGE_KEEP;
-
if (clear_page_dirty_for_io(page)) {
int res;
struct writeback_control wbc = {
@@ -504,18 +464,58 @@ static unsigned long shrink_page_list(st
if (!sc->may_writepage)
goto keep_locked;

+ /*
+ * If the page is dirty, only perform writeback if
+ * that write will be non-blocking. To prevent this
+ * allocation from being stalled by pagecache
+ * activity. But note that there may be stalls if
+ * we need to run get_block(). We could test
+ * PagePrivate for that.
+ *
+ * If this process is currently in
+ * generic_file_write() against this page's queue,
+ * we can perform writeback even if that will block.
+ *
+ * If the page is swapcache, write it back even if
+ * that would block, for some throttling. This happens
+ * by accident, because swap_backing_dev_info is bust:
+ * it doesn't reflect the congestion state of the
+ * swapdevs. Easy to fix, if needed.
+ * See swapfile.c:page_queue_congested().
+ */
+ if (!is_page_cache_freeable(page))
+ goto keep_locked;
+ if (!mapping) {
+ /*
+ * Some data journaling orphaned pages can
+ * have page->mapping == NULL while being
+ * dirty with clean buffers.
+ */
+ if (PagePrivate(page)) {
+ if (try_to_free_buffers(page)) {
+ ClearPageDirty(page);
+ printk("%s: orphaned page\n",
+ __FUNCTION__);
+ goto release_page;
+ }
+ }
+ goto keep_locked;
+ }
+ if (mapping->a_ops->writepage == NULL)
+ goto activate_locked;
+ if (!may_write_to_queue(mapping->backing_dev_info))
+ goto keep_locked;
+
/* Page is dirty, try to write it out here */
switch(pageout(page, mapping)) {
- case PAGE_KEEP:
- goto keep_locked;
case PAGE_ACTIVATE:
goto activate_locked;
case PAGE_SUCCESS:
if (PageWriteback(page) || PageDirty(page))
goto keep;
/*
- * A synchronous write - probably a ramdisk. Go
- * ahead and try to reclaim the page.
+ * A synchronous write - probably a ramdisk.
+ * Go ahead and try to reclaim the page.
*/
if (TestSetPageLocked(page))
goto keep;
@@ -526,7 +526,7 @@ static unsigned long shrink_page_list(st
; /* try to free the page below */
}
}
-
+release_page:
/*
* If the page has buffers, try to free the buffer mappings
* associated with this page. If we succeed we try to free

--
-
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