[PATCH] add AOP_TRUNCATED_PAGE, prepend AOP_ to WRITEPAGE_ACTIVATE

readpage(), prepare_write(), and commit_write() callers are updated to
understand the special return code AOP_TRUNCATED_PAGE in the style of
writepage() and WRITEPAGE_ACTIVATE.  AOP_TRUNCATED_PAGE tells the caller that
the callee has unlocked the page and that the operation should be tried again
with a new page.  OCFS2 uses this to detect and work around a lock inversion in
its aop methods.  There should be no change in behaviour for methods that don't
return AOP_TRUNCATED_PAGE.

WRITEPAGE_ACTIVATE is also prepended with AOP_ for consistency and they are
made enums so that kerneldoc can be used to document their semantics.

Signed-off-by: Zach Brown <zach.brown@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index b0cd81c32de6..795a050fe471 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -367,7 +367,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping)
                 res = mapping->a_ops->writepage(page, &wbc);
                 if (res < 0)
                         handle_write_error(mapping, page, res);
-                if (res == WRITEPAGE_ACTIVATE) {
+                if (res == AOP_WRITEPAGE_ACTIVATE) {
                         ClearPageReclaim(page);
                         return PAGE_ACTIVATE;
                 }