From patchwork Mon Oct 3 00:46:38 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ian Kent X-Patchwork-Id: 9359885 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 2DF4D60459 for ; Mon, 3 Oct 2016 00:50:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3B3712898A for ; Mon, 3 Oct 2016 00:50:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2ACC0289DF; Mon, 3 Oct 2016 00:50:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A921B2898A for ; Mon, 3 Oct 2016 00:50:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752470AbcJCAs3 (ORCPT ); Sun, 2 Oct 2016 20:48:29 -0400 Received: from out4-smtp.messagingengine.com ([66.111.4.28]:50778 "EHLO out4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752268AbcJCAqm (ORCPT ); Sun, 2 Oct 2016 20:46:42 -0400 Received: from compute7.internal (compute7.nyi.internal [10.202.2.47]) by mailout.nyi.internal (Postfix) with ESMTP id 92A342068D; Sun, 2 Oct 2016 20:46:41 -0400 (EDT) Received: from frontend1 ([10.202.2.160]) by compute7.internal (MEProxy); Sun, 02 Oct 2016 20:46:41 -0400 DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=themaw.net; h=cc :content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to:x-sasl-enc :x-sasl-enc; s=mesmtp; bh=U5Sm4sM1RAiKd+/Yb8u0SkJ3izo=; b=IynNV8 835e6BR/v6hNQ2G9N7+qv3MCZZNPAL2NQpnOegNIM4cGPW59L8CwkYiVycGwQ4qe H0O1eLYw5JV1zTrFOrDCDRaqYtPCOG47rGob8ijZMrsRZEgO5C9ViNXLriJ+ntsC /TstK2A2qwm9IHAt1EbyQ029/05Aec2ref1/o= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:in-reply-to:message-id:mime-version:references :subject:to:x-sasl-enc:x-sasl-enc; s=smtpout; bh=U5Sm4sM1RAiKd+/ Yb8u0SkJ3izo=; b=Wy23KRfpGaUBkw+KJSgBN4AON4fTHXx57RODm04G02QsBPg 55/NxWXdXtfRQ9OAGuNbdnyCaBbCa1L9JGzrK1jRsnWzOTJjndIbUBwJuwisoMaW ox9Y9Ee0HdNmoi2nFl3iIZ6s27ZbGidyJSzPNY0joetlgFfCHpIvoR97Z/nY= X-Sasl-enc: eP8EAcMeLom0oxhaqmzq62d0RXeiX6aVlgLlTxXSn6WN 1475455601 Received: from pluto.themaw.net (58-6-77-201.dyn.iinet.net.au [58.6.77.201]) by mail.messagingengine.com (Postfix) with ESMTPA id 0A6A4F2988; Sun, 2 Oct 2016 20:46:41 -0400 (EDT) Received: from pluto.themaw.net (localhost [127.0.0.1]) by pluto.themaw.net (Postfix) with ESMTP id BAE32A008E; Mon, 3 Oct 2016 08:46:38 +0800 (AWST) Subject: [RFC PATCH 3/8] vfs - add path_has_submounts() From: Ian Kent To: Kernel Mailing List Cc: autofs mailing list , Al Viro , linux-fsdevel , Omar Sandoval , Andrew Morton , "Eric W. Biederman" Date: Mon, 03 Oct 2016 08:46:38 +0800 Message-ID: <20161003004638.4865.71341.stgit@pluto.themaw.net> In-Reply-To: <20161003003646.4865.42500.stgit@pluto.themaw.net> References: <20161003003646.4865.42500.stgit@pluto.themaw.net> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Ian Kent d_mountpoint() can only be used reliably to establish if a dentry is not mounted in any namespace. It isn't aware of the possibility there may be multiple mounts using the given dentry, possibly in a different namespace. Add function, path_has_submounts(), that checks is a struct path contains mounts (or is a mountpoint itself) to handle this case. Signed-off-by: Ian Kent Cc: Al Viro Cc: Eric W. Biederman Cc: Omar Sandoval --- fs/dcache.c | 35 +++++++++++++++++++++++++++++++++++ include/linux/dcache.h | 1 + 2 files changed, 36 insertions(+) -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html diff --git a/fs/dcache.c b/fs/dcache.c index 5c7cc95..872f04e 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1306,6 +1306,41 @@ int have_submounts(struct dentry *parent) } EXPORT_SYMBOL(have_submounts); +struct check_mount { + struct vfsmount *mnt; + unsigned int mounted; +}; + +static enum d_walk_ret path_check_mount(void *data, struct dentry *dentry) +{ + struct check_mount *info = data; + struct path path = { .mnt = info->mnt, .dentry = dentry }; + + if (path_is_mountpoint(&path)) { + info->mounted = 1; + return D_WALK_QUIT; + } + return D_WALK_CONTINUE; +} + +/** + * path_has_submounts - check for mounts over a dentry in the + * current namespace. + * @parent: path to check. + * + * Return true if the parent or its subdirectories contain + * a mount point in the current namespace. + */ +int path_has_submounts(struct path *parent) +{ + struct check_mount data = { .mnt = parent->mnt, .mounted = 0 }; + + d_walk(parent->dentry, &data, path_check_mount, NULL); + + return data.mounted; +} +EXPORT_SYMBOL(path_has_submounts); + /* * Called by mount code to set a mountpoint and check if the mountpoint is * reachable (e.g. NFS can unhash a directory dentry and then the complete diff --git a/include/linux/dcache.h b/include/linux/dcache.h index ad2df92..5c5d197 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -255,6 +255,7 @@ extern void d_prune_aliases(struct inode *); /* test whether we have any submounts in a subdir tree */ extern int have_submounts(struct dentry *); +extern int path_has_submounts(struct path *); /* * This adds the entry to the hash queues.