Re: ext4 features

Jeffrey V. Merkey
2006-07-05T05:40:33Z

H. Peter Anvin wrote:

> Bill Davidsen wrote:
>
>>>
>>> DC> Easily doable in userspace, why bother with kernel programming
>>>
>>> In userspace you can't automatically delete the files when the space
>>> becomes needed. The LD_PRELOAD/glibc methods also have the
>>> disadvantage of having to figure out where a file goes when it's
>>> deleted, depending on which device it happens to reside on. Demanding
>>> read access to /proc/mounts just to do rm could cause problems.
>>>
>>> Userspace has had 10 years to invent a good solution. If it was so
>>> easy, it would probably have been done.
>>>
>> Actually, if it were so important it WOULD have been done. I suspect
>> that the issue is not lack of a good solution, but lack of a good
>> problem. The behavior you propose requires a lot of kernel
>> cleverness, including make the inodes seem to go away, so the count
>> is "right" for what the user sees.
>>
>
> The real solution for it is snapshots.

Peter,

Explain what you are thinking here. What I proposed, I have already
implemented in NetWare, it's very easy to do. Snapshotting is not
complex for FS's but does require a lot of space for meta-data to manage
it. EXT is not architecteced for something this complex. A simple
hidden mv is much easier to do.

Jeff

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