Re: partially encrypted filesystem

[Jeff Garzik]

Linus Torvalds wrote:
> With an encrypted filesystem, you can't do that. Or rather: you can do it
> if the filesystem is read-only, but you definitely CANNOT do it on
> writing. For writing you have to marshall the output buffer somewhere
> else (and quite frankly, it tends to become a lot easier if you can do
> that for reading too).
>
> And that in turn causes problems. You get all kinds of interesting
> deadlock schenarios when write-out requires more memory in order to
> succeed. So you need to get careful. Reading ends up being the much easier
> case (doesn't have the same deadlock issues _and_ you could do it in-place
> anyway).


FWIW zisofs and ntfs have to do this too, since X on-disk compressed 
pages must be expanded to X+Y in-memory pages...

	Jeff



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