Re: inconsistent mount attributes (ro/rw), RHEL5 / Netapp

["Gregory Baker" <gregory.baker@amd.com>]

Gregory Baker wrote:

> So the deal is, the mount flags (and NFS options) are set only the first 
> time that a given combination of server and filesystem are mounted. If 
> you ever mount the same filesystem from the same server on another 
> mountpoint, you'll get the flags and options that were passed on to the 
> first mount. There's no working around that.
> *****

Should these mount flags (and NFS options) expire/be removed from some 
table somewhere when you unmount/remount the filesystem?  The mount 
flags (and NFS options) persist between complete unmounting / remounting 
of said filesystem.

[greg@apathy 115656]$ cat typescript

* Look at me.  Don't have anything mounted via NFS yet the mount
* gets stuck as ro when mounted...

[root@adcgar04 tmp]# umount -a -t nfs
[root@adcgar04 tmp]# mount -v | grep pandora
[root@adcgar04 tmp]# cat /proc/mounts | grep pandora
[root@adcgar04 tmp]# mount eng:/vol/vol4/pandora/pandora-k26_g25_64-2 /mnt2
[root@adcgar04 tmp]# mount -v | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 on /mnt2 type nfs 
(rw,addr=163.181.34.137)
[root@adcgar04 tmp]# cat /proc/mounts | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 /mnt2 nfs 
ro,vers=3,rsize=65536,wsize=65536,hard,intr,proto=tcp,timeo=600,retrans=2,sec=sys,addr=eng 
0 0
[root@adcgar04 tmp]# touch /mnt2/asdf
touch: cannot touch `/mnt2/asdf': Read-only file system

* OK, let's try this fancy mount command..

[root@adcgar04 tmp]# mount -o remount,rw /mnt2
[root@adcgar04 tmp]#  mount -v | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 on /mnt2 type nfs 
(rw,remount,addr=163.181.34.137)
[root@adcgar04 tmp]#  cat /proc/mounts | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 /mnt2 nfs 
rw,vers=3,rsize=65536,wsize=65536,hard,intr,proto=tcp,timeo=600,retrans=2,sec=sys,addr=eng 
0 0

* Everybody is happy!

[root@adcgar04 tmp]#  touch /mnt2/asdf

* Let's get rid of NFS mount and see what happens now

[root@adcgar04 tmp]# umount /mnt2
[root@adcgar04 tmp]#  mount -v | grep pandora
[root@adcgar04 tmp]#  cat /proc/mounts | grep pandora
[root@adcgar04 tmp]#  mount eng:/vol/vol4/pandora/pandora-k26_g25_64-2 /mnt2
[root@adcgar04 tmp]# mount -v | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 on /mnt2 type nfs 
(rw,addr=163.181.34.137)
[root@adcgar04 tmp]# cat /proc/mounts | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 /mnt2 nfs 
rw,vers=3,rsize=65536,wsize=65536,hard,intr,proto=tcp,timeo=600,retrans=2,sec=sys,addr=eng 
0 0

* Everybody is happy!

[root@adcgar04 tmp]# touch /mnt2/asdf

* Let's give "something" the notion that this is a ro mount...

[root@adcgar04 tmp]# mount -o remount,ro /mnt2
[root@adcgar04 tmp]#  mount -v | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 on /mnt2 type nfs 
(ro,remount,addr=163.181.34.137)
[root@adcgar04 tmp]#  cat /proc/mounts | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 /mnt2 nfs 
ro,vers=3,rsize=65536,wsize=65536,hard,intr,proto=tcp,timeo=600,retrans=2,sec=sys,addr=eng 
0 0

* RO (expected)

[root@adcgar04 tmp]# touch /mnt2/asdf
touch: cannot touch `/mnt2/asdf': Read-only file system

* OK, unmount NFS mount, try again

[root@adcgar04 tmp]#  umount /mnt2
[root@adcgar04 tmp]#  mount -v | grep pandora
[root@adcgar04 tmp]#  cat /proc/mounts | grep pandora
[root@adcgar04 tmp]#  mount eng:/vol/vol4/pandora/pandora-k26_g25_64-2 /mnt2
[root@adcgar04 tmp]#  mount -v | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 on /mnt2 type nfs 
(rw,addr=163.181.34.137)
[root@adcgar04 tmp]#  cat /proc/mounts | grep pandora
eng:/vol/vol4/pandora/pandora-k26_g25_64-2 /mnt2 nfs 
ro,vers=3,rsize=65536,wsize=65536,hard,intr,proto=tcp,timeo=600,retrans=2,sec=sys,addr=eng 
0 0

* Boo-RO/RW (unexpected)

[root@adcgar04 tmp]#  touch /mnt2/asdf
touch: cannot touch `/mnt2/asdf': Read-only file system
[root@adcgar04 tmp]# exit

* So it seems that something remembers the last mount permissions, even
* though mount -v and /proc/mount do not show a filesystem mounted.
* The permissions persist to be associated with the exported filesystem.
* What causes this?  Note: it's not the automounter process; this was
* stopped during testing.


-- 
----------------------------------------------------------------------
Greg Baker                                         512-602-3287 (work)
gregory.baker@amd.com                              512-602-6970 (fax)
5204 E. Ben White Blvd MS 625                      512-555-1212 (info)
Austin, TX 78741




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