quota: Move down dqptr_sem read after initializing default warn[] type at __dquot_alloc_space().

sb->s_dqopt->dqptr_sem is used to serialize ops using pointers from inode to
dquots.  But for __dquot_alloc_space(), it could be safely moved down after the
default warn[] array got initialized.
Signed-off-by: Jie Liu <jeff.liu@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/dquot.c

@@ -1589,10 +1589,10 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
 		goto out;
 	}
 
-	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++)
 		warn[cnt].w_type = QUOTA_NL_NOWARN;
 
+	down_read(&sb_dqopt(inode->i_sb)->dqptr_sem);
 	spin_lock(&dq_data_lock);
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 		if (!dquots[cnt])