writeback: don't propagate AOP_WRITEPAGE_ACTIVATE

This is a writeback-internal marker but we're propagating it all the way back
to userspace!.

Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 4073d531cd7..33485213158 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -849,8 +849,10 @@ retry:
 
                         ret = (*writepage)(page, wbc, data);
 
-                        if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
+                        if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
                                 unlock_page(page);
+                                ret = 0;
+                        }
                         if (ret || (--(wbc->nr_to_write) <= 0))
                                 done = 1;
                         if (wbc->nonblocking && bdi_write_congested(bdi)) {