nommu: ramfs: don't leak pages when adding to page cache fails

When a ramfs nommu mapping is expanded, contiguous pages are allocated
and added to the pagecache.  The caller's reference is then passed on
by moving whole pagevecs to the file lru list.

If the page cache adding fails, make sure that the error path also
moves the pagevec contents which might still contain up to PAGEVEC_SIZE
successfully added pages, of which we would leak references otherwise.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Enrik Berkhan <Enrik.Berkhan@ge.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ramfs/file-nommu.c

@@ -129,6 +129,7 @@ int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
 	return -EFBIG;
 
  add_error:
+	pagevec_lru_add_file(&lru_pvec);
 	page_cache_release(pages + loop);
 	for (loop++; loop < npages; loop++)
 		__free_page(pages + loop);