[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/fs/mpage.c b/fs/mpage.c
index c5adcdddf3cc..f1d2d02bd4c8 100644
--- a/fs/mpage.c
+++ b/fs/mpage.c
@@ -721,7 +721,7 @@ retry:
                                                 &last_block_in_bio, &ret, wbc,
                                                 page->mapping->a_ops->writepage);
                         }
-                        if (unlikely(ret == WRITEPAGE_ACTIVATE))
+                        if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
                                 unlock_page(page);
                         if (ret || (--(wbc->nr_to_write) <= 0))
                                 done = 1;