Messages in this thread | | | Date | Thu, 11 Dec 2003 20:48:15 +0100 | From | Jörn Engel <> | Subject | Re: Is there a "make hole" (truncate in middle) syscall? |
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On Thu, 11 December 2003 11:15:28 -0800, Hua Zhong wrote: > > > The abstract interface for make_hole() is simple, but it turns into a > > pretty expensive filesystem operation, I think. After many cycles of > > free/allocate, your file would be badly fragmented across the > > filesystem. > > Understood. Two filesystems we are using: tmpfs and ext3. For the > former, fragmentation doesn't matter. > > Hey, I think when I get some cycles I can try to implement this for > tmpfs (since it's simpler) myself, and post a patch. :-) But before > that, I want to make sure it's doable.
If you really do it, please don't add a syscall for it. Simply check each written page if it is completely filled with zero. (This will be a very quick check for most pages, as they will contain something nonzero in the first couple of words)
Jörn
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