tsh at mrc-lmb.cam.ac.uk
Tue Dec 19 16:51:59 UTC 2006
>T. Horsnell wrote:
>> This is just the job. I dont even have to use udev to get
>> persistent device names if I use LABEL= in fstab. One question
>> In the absence of an fsid= option, how does Linux compute a
>> filesystem handle? Unless I know this, or unless I provide
>> an fsid= option for *all* my exported filesystems, I risk
>> choosing an id which may collide with the Linux-generated one.
>Trond (nfs maintainer) indicated to someone
>else on the kernel list:
> stat --printf "%D\n" /filesystem
Roger, thanks for this pointer. My 'stat' (FC6 updated as of today)
seems to have some oddities. To get filesystem-id as opposed to
device-id I have to:
stat --printf "%i\n" -f /filesystem
and when I do this all my filesystem-id's are zero.
stat --printf "%D\n" /filesystem
gets me a device-id which seems to be 256*majorno+minorno
Maybe I should try and contact Trond.
>Will print out the fsid for that filesystem on the
>nfs server, the stat command does seem to have some
>different arguements rather than --printf so if it yells
>read the man page and change the arguement.
>In situations where the major/minor could change, I add
>fsid to all filesystems.
>Also note that if you export the same filesystem twice
>then it has the same fsid and only one set of permissions
>ie both mounts are either rw or ro (probably whichever
>is last), and if you use separate fsid's for each, the
>permissions for each can now be different.
Do you mean that an /etc/exports which contains:
/fs1 client1(rw,fsid=1) client2(ro,fsid=1)
will be readonly by client1 and client2, whereas
/fs1 client1(rw,fsid=1) client2(ro,fsid=2)
will be rw by client1 and ro by client2 ?
I wonder what happens with:
/fs1 client1(rw,fsid=1) client2(ro)
/fs1 client1(rw) client2(ro,fsid=1)
maybe I'll do the experiment, but I wish there was a spec for
this. Undocumented properties have a habit of changing at the
drop of a kernel version.
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