Re: fs/crypt ioctl and attr

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Feb 08, 2017 at 09:21:27AM -0500, Theodore Ts'o wrote:
> On Tue, Feb 07, 2017 at 08:36:13PM -0800, Darrick J. Wong wrote:
> > As one of 'those people', I think I'm well qualified to say that a fake
> > xattr having side effects that doesn't behave in quite the same ways as
> > regular xattrs is setting up other programs (the ones that listxattr all
> > the attrs and getxattrs them) for all kinds of weird yuckiness.  And by
> > 'weird yuckiness' I mean "this one magic xattr returned EOPNOTSUPP and
> > the whole backup program exploded".
> > 
> > Now granted you can argue that we're just shifting that into an ioctl,
> > but ioctls are already weird and yucky. :)
> 
> If we were going to do anything at all, it would be to move it to a
> syscall.  But given that it took ***years*** for the glibc developers
> to get around to adding getrandom(2) to glibc, we'd be stuck using the
> syscall(3) interface and having to deal with different syscall numbers
> for different architectures (in case we're compiling on a system which
> hadn't update the kernel headers in /usr/include), and so at least in
> the short term it would actually be worse than using ioctl's.
> 
> For similar reasons I don't think there's going to be that much
> interest in adding a syscall to replace XFS_IOC_GOINGDOWN.  We'll
> probably go with FS_IOC_GOINGDOWN, just as we have with
> FS_IOC_SETFLAGS, etc.
> 
> Speaking of XFS_IOC_GOINGDOWN, I'm sure the name was coined many, many
> years agoo, back when concerns such as "avoiding a hostile working
> environment" were much of an issue.  Even so, I note that *someone*
> decided that the name that should be exposed to customer (in the
> xfs_io man page), was "shutdown", and not "goingdown".  So is there
> any objection if we use the name FS_IOC_SHUTDOWN moving forward?

None here.  I think Dave asked for GOINGDOWN -> SHUTDOWN too.

> Some might accuse us of being overly concerned about political
> correctness, but I have to admit I did have a slight twinge when I
> checked in the ext4 shutdown changes into our internal kernel.  I was
> worried that there might be some folks who might have found the name
> at least a tiny bit offensive.  (Not that anyone complained, but I'd
> much rather be conservative in what we send, and liberal in what we
> accept.)

Yes, and I further argue that io control command (ioctl) names should be
imperative.  One doesn't yell 'going down!' to turn off the light
switches. :P

--D

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> 	     	     	      	  - Ted
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