Re: Plugin for corruption resistance?

[David Masover <ninja@slaphack.com>]

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Christian Iversen wrote:
| On Thursday 17 February 2005 05:10, David Masover wrote:
|
|>Adam wrote:
|>| Hans Reiser <reiser <at> namesys.com> writes:
|>|>Its on the legitimate wish list, if someone wants to code it, let me
|>|> know.
|>|
|>| Hans, does this mean that you think that this type of functionality
|>
|>should be
|>
|>| implemented as a Reiser4 plugin and therefore in kernelspace?  Why
|>
|>wouldn't this
|>
|>| be better implemented in userspace via a daemon that is notified of file
|>| modification via dnotify/inotify?
|>
|>Because dnotify/inotify don't scale.  I don't think they lock on event,
|>either, whereas a plugin could guarentee that the hash was up-to-date
|>(no race conditions).
|>
|>We've been over this before.  There's a reason reiser4 and its plugins
|>are in kernel space, and not in something like Fuse.
|
|
| And, surely, updating a hash value when 1 byte changes in a gigabyte
file,
| would be much faster from kernel space where you can actually see the
| changeset?

Wouldn't it be sane to just export the changeset to userland?

This way is easier, though.  But I was thinking about accessing the
file.  I don't know of any hashes that can be easily updated from part
of the file, unless you're hashing only pieces of the file in the first
place, but it'd be nice to not bother hashing at all until the hash is
needed, especially if we are hashing the whole file.

Plus, there's the race condition thing.  Definitely a lot of reasons to
put more stuff in the kernel.

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