Re: Interface for the new fallocate() system call

From: Jakub Jelinek
Date: Fri Mar 30 2007 - 03:17:00 EST


On Thu, Mar 29, 2007 at 10:10:10AM -0700, Andrew Morton wrote:
> > Platform: s390
> > --------------
> > s390 prefers following layout:
> >
> > int fallocate(int fd, loff_t offset, loff_t len, int mode)
> >
> > For details on why and how "int, int, loff_t, loff_t" is a problem on
> > s390, please see Heiko's mail on 16th March. Here is the link:
> > http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg133595.html
> >
> > Platform: ppc, arm
> > ------------------
> > ppc (32 bit) has a problem with "int, loff_t, loff_t, int" layout,
> > since this will result in a pad between fd and offset, making seven
> > arguments total - which is not supported by ppc32. It supports only
> > 6 arguments. Thus the desired layout by ppc32 is:
> >
> > int fallocate(int fd, int mode, loff_t offset, loff_t len)
> >
> > Even ARM prefers above kind of layout. For details please see the
> > definition of sys_arm_sync_file_range().
>
> This is a clean-looking option. Can s390 be changed to support seven-arg
> syscalls?

Wouldn't
int fallocate(loff_t offset, loff_t len, int fd, int mode)
work on both s390 and ppc/arm? glibc will certainly wrap it and
reorder the arguments as needed, so there is no need to keep fd first.

Jakub
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