mounting /usr readonly

[John Summerfield]

Robert P. J. Day wrote:
> On Sun, 30 Dec 2007, John Summerfield wrote:
> 
>> Robert P. J. Day wrote:
> 
> ... snip ...
> 
>>>   can i assume that, as long as nothing is open for write, the
>>> read-only remount should work?  is there any other reason that i
>>> would be told that the device is busy.  put another way, if i run
>>> the above command and don't see an "F", should the remount always
>>> work?
> 
>> Add ro to the mount options in /etc/fstab and see what complains.
                                                   ^^^^^^^^^^^^^^^^^
> 
> but that wasn't the question.  again, if i try to, in one operation,
> remount a filesystem readonly with "mount -o remount,ro", is the only
> possible reason that remount could fail is if something on that
> filesystem is open for writing, which would show up in the output of
> "fuser -muv"?

I've previously found it beyond my ability to find (using lsof) 
everything that's open on a filesystem (I seem to recall problems with 
an nfs mount). In my case I suspected a kernel module.

> 
> or is it possible that that remount could fail because of "device
> busy" and i run that fuser command and i don't see anything marked
> with "F", which means there's another reason for the remount failure,
> and what might that be?

About the only thing I'm sure about "device busy" messages is that it 
does not mean the device is busy.





-- 

Cheers
John

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