Re: posix_fallocate

[David Holland <dholland-tech%netbsd.org@localhost>]

On Sun, Nov 17, 2013 at 10:24:04AM +0100, Emmanuel Dreyfus wrote:
 > > I think the chief question at this level is whether to support the
 > > "keep the length" flag for fallocate, fdiscard, both, or neither. The
 > > linux fallocate uses this to allow allocating blocks past EOF, which
 > > strikes me as nuts; 
 > 
 > Why is it bad?

What Mouse said, pretty much. Not only is it semantic nonsense, it
requires reworking fsck.

 > I am interested to port software, and of course it uses
 > FALLOC_FL_KEEP_SIZE and FALLOC_FL_PUNCH_HOLE...

FALLOC_FL_PUNCH_HOLE is fdiscard(). I don't believe in deleting things
by making an allocate call, or perpetrating other people's bad design
to avoid patching a couple packages.

The question is whether FALLOC_FL_KEEP_SIZE makes sense; it does for
fdiscard, but I remain unconvinced in the case of fallocate.

-- 
David A. Holland
dholland%netbsd.org@localhost