Re: RESVSP problems

[Eric Sandeen <sandeen@sandeen.net>]

David Chinner wrote:

>>> yeah... ISTR that the arguments are funky.  I can't remember if it's a
>>> bug or not.  :)  FWIW, allocsp just writes zeros to the file, so you
>>> could do it just as well from userspace w/ no fancy ioctls...  ALLOCSP
>>> is a bit pointless if you ask me... though maybe someone knows why it's
>>> there :)
>> Let me say that I have noticed that using ALLOCSP seems to create less extents 
>> than posix_fallocate/manual zeroing.
> 
> Yes, that's likely ;)
> 
> There's work currently active to make posix_fallocate() do the same thing
> as ALLOCSP (i.e. call into the filesystem and let it do smart stuff), but
> that's a ways off yet...

Dave, doesn't ALLOCSP actually create actual zeroed space though? 
Pretty much as posix_fallocate from userspace does today, maybe with 
better allocation... And "smart stuff" would be *not* needing to write 
zeros.... i.e. what RESVSP does.

-Eric