[PATCH] Use __GFP_HIGH in mpage_writepages()

In mpage_writepage(), use __GFP_HIGH when allocating the BIO: writeback
is a memory reclaim function and is entitle to dip into the page
reserves to get its IO underway.

fs/mpage.c

@@ -431,7 +431,7 @@ mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
 		unsigned nr_bvecs = MPAGE_BIO_MAX_SIZE / PAGE_CACHE_SIZE;
 
 		bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
-					nr_bvecs, GFP_NOFS);
+					nr_bvecs, GFP_NOFS|__GFP_HIGH);
 		if (bio == NULL)
 			goto confused;
 	}