block: use an on-stack bio in blkdev_issue_flush

There is no point in allocating memory for a synchronous flush.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Acked-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
index 807119a..b9e3db3 100644
--- a/fs/hfsplus/super.c
+++ b/fs/hfsplus/super.c
@@ -239,7 +239,7 @@ static int hfsplus_sync_fs(struct super_block *sb, int wait)
 	mutex_unlock(&sbi->vh_mutex);
 
 	if (!test_bit(HFSPLUS_SB_NOBARRIER, &sbi->flags))
-		blkdev_issue_flush(sb->s_bdev, GFP_KERNEL);
+		blkdev_issue_flush(sb->s_bdev);
 
 	return error;
 }