Messages in this thread | | | Date | Wed, 3 Dec 2003 18:08:53 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: partially encrypted filesystem |
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On Wed, 3 Dec 2003, Jeff Garzik wrote: > Linus Torvalds wrote: > > > > 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...
Note how zisofs only has to handle the read-only case. cramfs does the same.
Reading is trivially done by having a few extra buffers (either through the buffer cache or explicit buffering).
Writing is the more interesting case. I don't know how well NTFS does in low-memory circumstances.
(Which is by no means to say that it is somehow impossible to get right: you just have to be careful).
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