xfs: Fix WARN_ON(delalloc) in xfs_vm_releasepage()

When a dirty page is truncated from a file but reclaim gets to it before
truncate_inode_pages(), we hit WARN_ON(delalloc) in
xfs_vm_releasepage(). This is because reclaim tries to write the page,
xfs_vm_writepage() just bails out (leaving page clean) and thus reclaim
thinks it can continue and calls xfs_vm_releasepage() on page with dirty
buffers.

Fix the issue by redirtying the page in xfs_vm_writepage(). This makes
reclaim stop reclaiming the page and also logically it keeps page in a
more consistent state where page with dirty buffers has PageDirty set.

Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 5f707e537171..3244c988d379 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -953,13 +953,13 @@ xfs_vm_writepage(
                 unsigned offset_into_page = offset & (PAGE_CACHE_SIZE - 1);
 
                 /*
-                 * Just skip the page if it is fully outside i_size, e.g. due
-                 * to a truncate operation that is in progress.
+                 * Skip the page if it is fully outside i_size, e.g. due to a
+                 * truncate operation that is in progress. We must redirty the
+                 * page so that reclaim stops reclaiming it. Otherwise
+                 * xfs_vm_releasepage() is called on it and gets confused.
                  */
-                if (page->index >= end_index + 1 || offset_into_page == 0) {
-                        unlock_page(page);
-                        return 0;
-                }
+                if (page->index >= end_index + 1 || offset_into_page == 0)
+                        goto redirty;
 
                 /*
                  * The page straddles i_size.  It must be zeroed out on each