[Libguestfs] [PATCH v2 4/4] file: Zero for block devices on old kernels

[Nir Soffer]

On Mon, Aug 13, 2018 at 9:00 PM Eric Blake <eblake at redhat.com> wrote:

> On 08/03/2018 02:28 PM, Nir Soffer wrote:
> > fallocate(FALLOC_FL_ZERO_RANGE) is supportd for block devices with
>
> s/supportd/supported/
>
> > modern kernel, but when it is not, we fall back to manual zeroing.
> >
> > For block device, try also to use ioctl(BLKZEROOUT) if offset and count
> > are aligned to block device sector size.
> >
> > Here is an example run without this change on RHEL 7.5:
> >
>
> > +++ b/plugins/file/file.c
> > @@ -41,14 +41,21 @@
> >   #include <unistd.h>
> >   #include <sys/types.h>
> >   #include <sys/stat.h>
> > +#include <sys/ioctl.h>
>
> Linux-specific header; will it cause grief on BSD compilation?
>

I did not know that, will wrap it with #ifdef __linux__


>
> (POSIX declares ioctl() in <stropts.h>, but for the obsolete STREAMS
> extension that no one but Solaris ever implemented, and which no one
> uses today - and thus which has little bearing on the Linux use of ioctl).
>
> Otherwise looks okay.
>
> --
> Eric Blake, Principal Software Engineer
> Red Hat, Inc.           +1-919-301-3266 <(919)%20301-3266>
> Virtualization:  qemu.org | libvirt.org
>
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