From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lennart Poettering Date: Fri, 03 Apr 2020 15:12:23 +0000 Subject: Re: Upcoming: Notifications, FS notifications and fsinfo() Message-Id: <20200403151223.GB34800@gardel-login> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <2418286.1585691572@warthog.procyon.org.uk> <20200401144109.GA29945@gardel-login> <2590640.1585757211@warthog.procyon.org.uk> <36e45eae8ad78f7b8889d9d03b8846e78d735d28.camel@themaw.net> <27994c53034c8f769ea063a54169317c3ee62c04.camel@themaw.net> <20200403111144.GB34663@gardel-login> In-Reply-To: To: Miklos Szeredi Cc: Ian Kent , David Howells , Christian Brauner , Linus Torvalds , Al Viro , dray@redhat.com, Karel Zak , Miklos Szeredi , Steven Whitehouse , Jeff Layton , andres@anarazel.de, keyrings@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Aleksa Sarai On Fr, 03.04.20 13:38, Miklos Szeredi (miklos@szeredi.hu) wrote: > On Fri, Apr 3, 2020 at 1:11 PM Lennart Poettering wrote: > > > > On Fr, 03.04.20 09:44, Ian Kent (raven@themaw.net) wrote: > > > > > > Currently the only way to find the mount id from a path is by parsing > > > > /proc/self/fdinfo/$fd. It is trivial, however, to extend statx(2) to > > > > return it directly from a path. Also the mount notification queue > > > > that David implemented contains the mount ID of the changed mount. > > > > I would love to have the mount ID exposed via statx(). > > Here's a patch. Oh, this is excellent. I love it, thanks! BTW, while we are at it: one more thing I'd love to see exposed by statx() is a simple flag whether the inode is a mount point. There's plenty code that implements a test like this all over the place, and it usually isn't very safe. There's one implementation in util-linux for example (in the /usr/bin/mountpoint binary), and another one in systemd. Would be awesome to just have a statx() return flag for that, that would make things *so* much easier and more robust. because in fact most code isn't very good that implements this, as much of it just compares st_dev of the specified file and its parent. Better code compares the mount ID, but as mentioned that's not as pretty as it could be so far... Lennart -- Lennart Poettering, Berlin