[GFS2] fix GFP_KERNEL misuses

There are several places where GFP_KERNEL allocations happen under a glock,
which will result in hangs if we're under memory pressure and go to re-enter the
fs in order to flush stuff out.  This patch changes the culprits to GFS_NOFS to
keep this problem from happening.  Thank you,

Signed-off-by: Josef Bacik <jbacik@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/inode.c

@@ -1231,7 +1231,7 @@ int gfs2_readlinki(struct gfs2_inode *ip, char **buf, unsigned int *len)
 
 	x = ip->i_di.di_size + 1;
 	if (x > *len) {
-		*buf = kmalloc(x, GFP_KERNEL);
+		*buf = kmalloc(x, GFP_NOFS);
 		if (!*buf) {
 			error = -ENOMEM;
 			goto out_brelse;