Re: [RFC] Heads up on sys_fallocate()

[Andreas Dilger]

On Mar 01, 2007  13:15 -0600, Eric Sandeen wrote:
> One thing I'd like to see is a cmd argument as well, to allow for 
> example allocation vs. reservation (i.e. allocating blocks vs. simply 
> reserving a number), as well as the inverse of those functions 
> (un-reservation, de-allocation)?
> 
> If the allocation interface allows allocation/reservation within 
> arbitrary ranges, if the only way to un-allocate is via a truncate, 
> that's pretty asymmetric.

I'd rather we just get the oft-discussed punch() syscall instead.
This is really what "unallocate" would do for persistent allocations
and it would be useful for files that were not preallocated.

For filesystems that don't implement punch glibc() would do zero-filling
of the punched area I guess (to make it equivalent to reading from a
hole in the file).

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

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