ramfs-nommu: use generic lru cache

Instead of open-coding the lru-list-add pagevec batching when expanding a
file mapping from zero, defer to the appropriate page cache function that
also takes care of adding the page to the lru list.

This is cleaner, saves code and reduces the stack footprint by 16 words
worth of pagevec.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.com>
Cc: MinChan Kim <minchan.kim@gmail.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/ramfs/file-nommu.c

@@ -59,7 +59,6 @@ const struct inode_operations ramfs_file_inode_operations = {
  */
 int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
 {
-	struct pagevec lru_pvec;
 	unsigned long npages, xpages, loop, limit;
 	struct page *pages;
 	unsigned order;
@@ -102,24 +101,20 @@ int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
 	memset(data, 0, newsize);
 
 	/* attach all the pages to the inode's address space */
-	pagevec_init(&lru_pvec, 0);
 	for (loop = 0; loop < npages; loop++) {
 		struct page *page = pages + loop;
 
-		ret = add_to_page_cache(page, inode->i_mapping, loop, GFP_KERNEL);
+		ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
+					GFP_KERNEL);
 		if (ret < 0)
 			goto add_error;
 
-		if (!pagevec_add(&lru_pvec, page))
-			__pagevec_lru_add_file(&lru_pvec);
-
 		/* prevent the page from being discarded on memory pressure */
 		SetPageDirty(page);
 
 		unlock_page(page);
 	}
 
-	pagevec_lru_add_file(&lru_pvec);
 	return 0;
 
  fsize_exceeded:
@@ -128,10 +123,8 @@ 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);
+	while (loop < npages)
+		__free_page(pages + loop++);
 	return ret;
 }