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/ext4/ialloc.c b/fs/ext4/ialloc.c
index b215c56..20f2fcb 100644
--- a/fs/ext4/ialloc.c
+++ b/fs/ext4/ialloc.c
@@ -1583,7 +1583,7 @@ int ext4_init_inode_table(struct super_block *sb, ext4_group_t group,
 	if (ret < 0)
 		goto err_out;
 	if (barrier)
-		blkdev_issue_flush(sb->s_bdev, GFP_NOFS);
+		blkdev_issue_flush(sb->s_bdev);
 
 skip_zeroout:
 	ext4_lock_group(sb, group);