[Tux3] Deferred Namespace Operations

Daniel Phillips phillips at phunq.net
Tue Nov 11 01:13:32 PST 2008


On Monday 10 November 2008 23:50, Maciej Żenczykowski wrote:
> I understood that one of the benefits of deferred creation, was that a
> later deletion could possibly end up with no disk i/o.  I was just
> pointing out, that this is still not quite the case, since we need to
> have enough data to later release the files data blocks... although I
> guess a deleted files data-blocks could be allocated while only
> marking their 'use' in in-memory-state (never writing it to disk).
> However, this seems highly error-prone and not worth it.  As such the
> above optimization can only really be done if we're deleting a file to
> which there are no more open references...

The data blocks will only be in the page cache (block cache in
userspace) and not even be assigned physical addresses before the
temporary file is deleted.  So they will just be removed from cache
by the VFS.  It would be pretty useless if only empty files could hit
this optimization.

Regards,

Daniel

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