Re: [OSR-devel] /etc/mtab

[Marc G. <gr...@at...>]

----- "Gordan Bobic" <go...@bo...> wrote:

> Is there a particular functional reason why /etc/mtab should be 
> symlinked to /proc/mounts instead of /cdsl.local/etc/mtab?
Yes there is.
> 
> The reason I ask two-fold:
> 
> 1) I'm not sure if having it symlinked to /proc/mounts confuses the 
> process of unmounting the file systems in the shared root during 
> shutdown. /proc/mounts shows all mounted file systems, including paths
> 
> that aren't mounted in the OSR root (e.g. /mnt/tmproot for the glfs 
> backing fs is mounted only in the initroot, but still shows up in 
> /proc/mounts).
> 
> 2) It seems to interfere with the checks to see whether a bind-mount
> is 
> already mounted. Under OSR, I'm seeing all bind-mounts in fstab
> getting 
> mounted twice, once when mounting local file systems, and once when 
> mounting "other" file systems.
This can be changed. Just add an options _netdev as option to the fstab an the bindmounts should only be mounted once.
> 
> Is anything likely to break if /etc/mtab is symlinked to 
> /cdsl.local/etc/mtab?
Yes.
First see:
https://partner-bugzilla.redhat.com/show_bug.cgi?id=214891
Then when mount <path> is executed with RHEL5 the following is done (if I recall it right).
All changes are done to a tmpfile /etc/mtab.tmp and this version gets newly created in /etc and afterwards copied back to /etc/mtab. The symlink to /cdsl.local does not survive. But if /etc/mtab is a symlink to /proc/mounts all of the above is ignored.

That's how I recall the background of this topic.

As this is in phase of being change it might be that there are changes already in RHEL5 latest U but not very likely.

It is easily to be tested:
rm /etc/mtab; touch /cdsl.local/etc/mtab; ln -s /cdsl.local/etc/mtab /etc/mtab; mount <somepath>; ls -l /etc/mtab.

Hope this helps
Marc
> 
> Gordan
> 
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