Hello Aneesh, On Sun, Mar 16, 2014 at 4:08 PM, Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote: > Michael Kerrisk <mtk.manpages@xxxxxxxxx> writes: > >> Hello Aneesh, >> >> I'm currently working on a man page for name_to_handle_at() and >> open_by_handle_at(), and I have a question relating to a point that >> probably needs to be covered in the man page. >> >> Back in July 2010, in this thread: >> http://thread.gmane.org/gmane.linux.file-systems/41782/focus=43131 >> you said: >> >> [[ >> mount id should not be looked at as a persistent identifier. It should >> be used to derive a persistent identifier from /proc/self/mountinfo. The >> persistent identifier could be the combination of device properties, >> file system properties or the uuid which is going to be an optional >> tag in /proc/self/mountinfo. >> ]] >> >> In the man page, I'd like to briefly describe how one derives such a >> persistent ID from mountinfo. AFAICS, the optional UUID tag in >> /proc/self/mountinfo has not come to pass. So, what then is the >> recommended practice for deriving the persistent ID? >> > > Anything that work for the application. mount_id will indicate which > mount it is ie. from /proc/self/mountinfo > > 30 20 8:1 / /boot rw,relatime - ext4 /dev/sda1 rw,data=ordered > > The value 30 helps us to figure out that we are looking at device > /dev/sda1. With that we can derive the uuid using libblkid. I am not sure we > concluded anything really about how to identify an nfs mount. May be we > can do that based on server and mount point details ?.But from the > syscall point, what we return is mount_id, which gives a hint regarding > which mount point we are talking about in /proc/self/mountinfo. From > that information applications can use any method that work for them > to derivce an unique identifier. > > I know that NFS ganesha use these syscall. May we can check with them > what worked for them ? (Added to CC:) Thanks, that helped, as as I hope is evident from the page I just sent. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
