Re: [PATCH] fuse: Add ioctl flag for compat ioctl with 64-bit time_t

[Ian Abbott]

On 24/04/2019 11:52, Miklos Szeredi wrote:
> On Tue, Apr 23, 2019 at 5:14 PM Ian Abbott <abbotti@xxxxxxxxx> wrote:
> > On 23/04/2019 13:55, Miklos Szeredi wrote:
> > > On Fri, Mar 1, 2019 at 6:08 PM Ian Abbott <abbotti@xxxxxxxxx> wrote:
> > > > Currently, a CUSE server running on a 64-bit kernel can tell when an
> > > > ioctl request comes from a process running a 32-bit ABI, but cannot tell
> > > > whether the requesting process is using legacy IA32 emulation or x32
> > > > ABI, for example.  In particular, the server does not know the size of
> > > > the client process's `time_t` type.
> > > >
> > > > For 64-bit kernels, the `FUSE_IOCTL_COMPAT` and `FUSE_IOCTL_32BIT` flags
> > > > are currently set in the ioctl input request (`struct fuse_ioctl_in`
> > > > member `flags`) for a 32-bit requesting process.  This patch defines a
> > > > new flag `FUSE_IOCTL_COMPAT_64TIME` and sets it if the 32-bit requesting
> > > > process (running on a 64-bit kernel) uses a 64-bit `time_t` type.
> > >
> > > Hi,
> > >
> > > Thanks for the patch.
> > >
> > > I think it should rather use in_x32_syscall() helper and follow that
> > > naming because there's apparently at least one example in xfs of a
> > > non-time_t related ioctl that varies between the x32 vs ia32.
> >
> > Hi Miklos,
> >
> > It is conceivable that COMPAT_USE_64BIT_TIME could be true for some
> > other arch/ABI (although currently it is only ever set for x86/x32).
> > Should it have separate flags for "compat 64-bit time" and "compat x32"
> > (even though that is currently redundant)?
>
> No, it should just be a single flag, something like
> FUSE_IOCTL_COMPAT_X32 and the documentation should say that it implies
> 64bit time values.

Okay, since the subject line, description and code will change, I'll 
submit the new patch as a new patch, rather than a "v2".  (I'll mention 
its history below the scissors line.)  Please drop this patch.

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