Revert "ceph: SetPageError() for writeback pages if writepages fails"

This reverts commit b109eec6f4.

If I'm filling up a filesystem with this sort of command:

    $ dd if=/dev/urandom of=/mnt/cephfs/fillfile bs=2M oflag=sync

...then I'll eventually get back EIO on a write. Further calls
will give us ENOSPC.

I'm not sure what prompted this change, but I don't think it's what we
want to do. If writepages failed, we will have already set the mapping
error appropriately, and that's what gets reported by fsync() or
close().

__filemap_fdatawait_range however, does this:

	wait_on_page_writeback(page);
	if (TestClearPageError(page))
		ret = -EIO;

...and that -EIO ends up trumping the mapping's error if one exists.

When writepages fails, we only want to set the error in the mapping,
and not flag the individual pages.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: "Yan, Zheng” <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/addr.c

@@ -703,9 +703,6 @@ static void writepages_finish(struct ceph_osd_request *req)
 				clear_bdi_congested(&fsc->backing_dev_info,
 						    BLK_RW_ASYNC);
 
-			if (rc < 0)
-				SetPageError(page);
-
 			ceph_put_snap_context(page_snap_context(page));
 			page->private = 0;
 			ClearPagePrivate(page);