staging/lustre/llite: do not clear uptodate bit in page delete

Otherwise, if the race between page fault and truncate occurs, it
will cause the page fault routine to return an EIO error.

In filemap_fault() {
    page_not_uptodate:
    ...
        ClearPageError(page);
        error = mapping->a_ops->readpage(file, page);
        if (!error) {
                wait_on_page_locked(page);
                if (!PageUptodate(page))
                        error = -EIO;
    }
    ...
}

However, I tend to think this is a defect in kernel implementation,
because it assumes PageUptodate shouldn't be cleared but file read
routine doesn't make the same assumption.
Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Reviewed-on: http://review.whamcloud.com/22827
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8633Reviewed-by: Li Dongyang <dongyang.li@anu.edu.au>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/vvp_page.c

@@ -166,7 +166,6 @@ static void vvp_page_delete(const struct lu_env *env,
 	refc = atomic_dec_return(&page->cp_ref);
 	LASSERTF(refc >= 1, "page = %p, refc = %d\n", page, refc);
 
-	ClearPageUptodate(vmpage);
 	ClearPagePrivate(vmpage);
 	vmpage->private = 0;
 	/*