Re: [PATCH v6 0/3] fallocate for block devices to provide zero-out

[Linus Torvalds]

On Fri, Mar 4, 2016 at 4:55 PM, Darrick J. Wong <darrick.wong@xxxxxxxxxx> wrote:
>
> This is a redesign of the patch series that fixes various interface
> problems with the existing "zero out this part of a block device"
> code.  BLKZEROOUT2 is gone.

I replied to two of the patches with small nits, but on the whole I
like it. The only nit that I think is serious is that you shouldn't be
requiring people to have to use FALLOC_FL_KEEP_SIZE.

If anything, you might just change that logic to say: If
FALLOC_FL_KEEP_SIZE is set, then we truncate the hole punching/zeroing
to the size of the device. So people could do something like

  fallocate(fd,
        FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE,
        0, ~0);

to trim the whole device (and if FALLOC_FL_KEEP_SIZE isn't set, then
the above would be an error simply because the requested hole was
bigger than the device)

            Linus