[PATCH 4/4] parse options in the vfs level

Glauber Costa glommer at parallels.com
Tue Aug 2 07:43:37 PDT 2011


On 08/02/2011 11:18 AM, Al Viro wrote:
> On Tue, Aug 02, 2011 at 10:04:06AM -0300, Glauber Costa wrote:
>
>> I am not sure either, but I still believe my proposal is superior to
>> write-to-a-file specifically. Writing to a file, be it in proc, sys,
>> or wherever, leaves a window of opportunity open between mounting a
>> filesystem and limiting its caches. Doing it on mount is atomic.
>>
>> Effectively, I see this limit as a property of a particular instance
>> of a mounted filesystem. Since all properties of a filesystem are
>> specified during mount, this becomes a natural extension.
>
> The trouble is, dentry tree is fundamentally a property of superblock.
> It's shared between *all* instances of that fs in all mount trees...

And how is it different from any fs-specific options, like the ones extX 
have, for instance ? Many of them seem to operate on a superblock.

If you mount a superblock somewhere, you can tweak specifics about its 
operation. If you mount it somewhere else, the assumption is you know 
what you're doing.




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