Re: The argument for fs assistance in handling archives

[Hans Reiser]

David Masover wrote:

> Spam wrote:
> [...]
> |>   I thought reiser4 had its journaling and atomic commits. Am I
> |>   mistaken? I run reiser4 as primary fs on my test systems and it seem
> |>   to work as expected.
>
> consider this:
>
> save_file () {
>     write()    /* what if the write flushes halfway through
>          * then crashes?

reiser4 does protect from this.  reiserfs v3 does not.

>          */
>
>     blah()    /* what if "blah" crashes? */
>     write()
> }
>
> Some apps need consistency across multiple files, but we don't even have
> it on a single file.  You need a new interface to do that.  As you can
> see, reiser4 has absolutely no way of knowing, anywhere in the above
> code, when you're done writing -- and when the file is consistent.
>
> AFAIK, all that has to be done now for this to work is for them to
> finish the userland interface to the journalling and atomic commits that
> already exist for kernel space.  But so far, all that is truly atomic is
> metadata operations -- chmod, mv, mkdir, touch, and rm/rmdir are all
> atomic, so long as you only use them on a single file/dir.  But this has
> been true in reiserfs3, xfs, ext3, and others.

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