Re: [PATCH] address_space_operations unification

From: Trond Myklebust (
Date: Mon May 08 2000 - 11:12:31 EST

>>>>> " " == Jamie Lokier <> writes:

> Trond Myklebust wrote:
>> If the change of 'symlink' causes cache invalidation then it
>> should work if you turn off caching.

> Can you turn off cacheing for the contents? man nfs(5)
> explains "noac" but that only forces attribute verification on
> every operation. It doesn't disable cacheing of the data, does
> it?

Sorry I was unneccessarily unclear. I meant if you use 'noac'. That
was why I said it was broken: you're relying on attribute checking to
invalidate the cache for you. If the attributes don't change, you're
essentially screwed.

>> Of course we can fix this for the special case of symlinks if
>> so desired.

> I don't think there's a need for an "no cache symlink" option,
> provided you can turn data cacheing off in general.

> For those cases where you have per-user symlinks and also files
> you'd like cached, you can simppy mount two NFS filesystems --
> one cached and one not.

No you cannot turn off caching. For symlinks (and possibly readdir)
you could do it by the simple expedient of invalidating the page cache
once the VFS is done with reading it. For files this isn't practical.


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