From: Nick Piggin <nickpiggin@yahoo.com.au>
Move the invocation of ->writepage for to-be-reclaimed pages into
its own function "pageout".
From: Nikita Danilov <nikita@namesys.com>
with small changes from Nick Piggin
Signed-off-by: Nick Piggin <nickpiggin@cyberone.com.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/mm/vmscan.c | 127 +++++++++++++++++++++++++++++++++-------------------
1 files changed, 81 insertions(+), 46 deletions(-)
diff -puN mm/vmscan.c~vmscanc-move-writepage-invocation-into-its-own-function mm/vmscan.c
--- 25/mm/vmscan.c~vmscanc-move-writepage-invocation-into-its-own-function 2004-05-31 16:40:25.107368456 -0700
+++ 25-akpm/mm/vmscan.c 2004-05-31 16:40:25.112367696 -0700
@@ -239,6 +239,77 @@ static void handle_write_error(struct ad
unlock_page(page);
}
+/* 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 */
+ PAGE_SUCCESS,
+ /* page is clean and locked */
+ PAGE_CLEAN,
+} pageout_t;
+
+/*
+ * pageout is called by shrink_list() for each dirty page. Calls ->writepage().
+ */
+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)
+ 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 = {
+ .sync_mode = WB_SYNC_NONE,
+ .nr_to_write = SWAP_CLUSTER_MAX,
+ .nonblocking = 1,
+ .for_reclaim = 1,
+ };
+
+ SetPageReclaim(page);
+ res = mapping->a_ops->writepage(page, &wbc);
+ if (res < 0)
+ handle_write_error(mapping, page, res);
+ if (res == WRITEPAGE_ACTIVATE) {
+ ClearPageReclaim(page);
+ return PAGE_ACTIVATE;
+ }
+ if (!PageWriteback(page)) {
+ /* synchronous write or broken a_ops? */
+ ClearPageReclaim(page);
+ }
+
+ return PAGE_SUCCESS;
+ }
+
+ return PAGE_CLEAN;
+}
+
/*
* shrink_list returns the number of reclaimed pages
*/
@@ -320,59 +391,21 @@ shrink_list(struct list_head *page_list,
}
page_map_unlock(page);
- /*
- * 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 (PageDirty(page)) {
if (referenced)
goto keep_locked;
- if (!is_page_cache_freeable(page))
- goto keep_locked;
- if (!mapping)
- goto keep_locked;
- if (mapping->a_ops->writepage == NULL)
- goto activate_locked;
if (!may_enter_fs)
goto keep_locked;
- if (!may_write_to_queue(mapping->backing_dev_info))
- goto keep_locked;
if (laptop_mode && !do_writepage)
goto keep_locked;
- if (clear_page_dirty_for_io(page)) {
- int res;
- struct writeback_control wbc = {
- .sync_mode = WB_SYNC_NONE,
- .nr_to_write = SWAP_CLUSTER_MAX,
- .nonblocking = 1,
- .for_reclaim = 1,
- };
-
- SetPageReclaim(page);
- res = mapping->a_ops->writepage(page, &wbc);
- if (res < 0)
- handle_write_error(mapping, page, res);
- if (res == WRITEPAGE_ACTIVATE) {
- ClearPageReclaim(page);
- goto activate_locked;
- }
- if (!PageWriteback(page)) {
- /* synchronous write or broken a_ops? */
- ClearPageReclaim(page);
- }
+
+ /* 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;
/*
@@ -384,6 +417,8 @@ shrink_list(struct list_head *page_list,
if (PageDirty(page) || PageWriteback(page))
goto keep_locked;
mapping = page_mapping(page);
+ case PAGE_CLEAN:
+ ; /* try to free the page below */
}
}
_