On Tue, Sep 25, 2012 at 10:02:35AM +0800, chenditang wrote:
> I have 1 question which need confirm.
>
> in the RHEL7.0alpha version
> nfs-utils-1.2.5-3.el7.x86_64 --> use mount_libmount.c
> util-linux-2.20.1-2.el7.x86_64
> when umount a NFS directory, the mnt_table_parse_mtab() function will merge user options(/run/mount/utab)
> into mountinfo(/proc/self/mountinfo)from kernel. if the mount number is large, leading to umount a directory
> time-consuming. the complexity of the algorithm is O(n(n+1)/2).
Yes, maybe we can somehow improve the file format and the algorithm,
suggestions?
> but in the old version(RHEL6.3GA/nfs-utils-1.2.3-26.el6.x86_64(use mount.c)), only according to the parameters of umount command,
> find the corresponding record in the /etc/mtab file
But we don't have mtab file in RHEL7 anymore, so we have to store the
userspace specific mount options somewhere... (/run/mount/utab). The
solution is to minimize number of information we have to maintain in
userspace.
Unfortunately it seems that for example on my system we duplicate the
information:
utab: retrans=20,addr=192.168.111.1
mountinfo: rw,vers=3,rsize=131072,wsize=131072,namlen=255,hard,proto=tcp,timeo=600,
retrans=20,sec=sys,mountaddr=192.168.111.1,mountvers=3,mountport=39755,
mountproto=udp,local_lock=none,addr=192.168.111.1
(see retrans= and addr=)
Maybe we can detect this situation and don't store duplicate options
in userspace. The question is what happen with retrans= and addr=
after remount. If I good remember there was any reason to maintain
these stuff in userspace. Chuck?
> Question)*:* merg the tow file are necessary for umount a dir?
I guess nfs umount needs the addr= info.
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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