From: Jann Horn Subject: Re: [PATCH] ioctl_getfsmap.2: document the GETFSMAP ioctl Date: Mon, 8 May 2017 00:17:53 +0200 Message-ID: References: <20170507155855.GD5970@birch.djwong.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Michael Kerrisk-manpages , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, Linux API , linux-man@vger.kernel.org To: "Darrick J. Wong" Return-path: In-Reply-To: <20170507155855.GD5970@birch.djwong.org> Sender: linux-fsdevel-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Sun, May 7, 2017 at 5:58 PM, Darrick J. Wong wrote: > Document the new GETFSMAP ioctl that returns the physical layout of a > (disk-based) filesystem. [...] > +.B EPERM > +This query is not allowed. Please document the circumstances under which a query is allowed. Also: From a quick glance at the XFS implementation, I don't see any privilege checks. Am I missing something, or does this API permit an unprivileged user to determine the number of physical blocks allocated for any inode, even for inodes the user can't ordinarily see in any way?