Re: partially encrypted filesystem

From: Jeff Garzik
Date: Wed Dec 03 2003 - 20:28:08 EST

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

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


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