ext4: cleanup GFP flags inside resize path

We must use GFP_NOFS instead GFP_KERNEL inside ext4_mb_add_groupinfo
and ext4_calculate_overhead() because they are called from inside a
journal transaction. Call trace:

ioctl
 ->ext4_group_add
   ->journal_start
   ->ext4_setup_new_descs
     ->ext4_mb_add_groupinfo -> GFP_KERNEL
   ->ext4_flex_group_add
     ->ext4_update_super
       ->ext4_calculate_overhead  -> GFP_KERNEL
   ->journal_stop

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 4831849..b643009 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -3300,7 +3300,7 @@
 	struct ext4_super_block *es = sbi->s_es;
 	ext4_group_t i, ngroups = ext4_get_groups_count(sb);
 	ext4_fsblk_t overhead = 0;
-	char *buf = (char *) get_zeroed_page(GFP_KERNEL);
+	char *buf = (char *) get_zeroed_page(GFP_NOFS);
 
 	if (!buf)
 		return -ENOMEM;