ext4: fix quota charging for shared xattr blocks

ext4_xattr_block_set() calls dquot_alloc_block() to charge for an xattr
block when new references are made. However if dquot_initialize() hasn't
been called on an inode, request for charging is effectively ignored
because ext4_inode_info->i_dquot is not initialized yet.

Add dquot_initialize() to call paths that lead to ext4_xattr_block_set().

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>

fs/quota/dquot.c

@@ -1512,6 +1512,22 @@ int dquot_initialize(struct inode *inode)
 }
 EXPORT_SYMBOL(dquot_initialize);
 
+bool dquot_initialize_needed(struct inode *inode)
+{
+	struct dquot **dquots;
+	int i;
+
+	if (!dquot_active(inode))
+		return false;
+
+	dquots = i_dquot(inode);
+	for (i = 0; i < MAXQUOTAS; i++)
+		if (!dquots[i] && sb_has_quota_active(inode->i_sb, i))
+			return true;
+	return false;
+}
+EXPORT_SYMBOL(dquot_initialize_needed);
+
 /*
  * Release all quotas referenced by inode.
  *