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Subject: Re: [RFC][PATCH] linux/uuid.h: hoist uuid_is_null() helper from
 libnvdimm
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Amir Goldstein <amir73il@gmail.com>, Christoph Hellwig <hch@lst.de>
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Date: Wed, 03 May 2017 19:35:52 +0300
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On Wed, 2017-05-03 at 15:42 +0300, Amir Goldstein wrote:
> On Wed, May 3, 2017 at 2:00 PM, Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> > On Wed, 2017-05-03 at 13:05 +0300, Amir Goldstein wrote:
> > > On Wed, May 3, 2017 at 12:13 PM, Andy Shevchenko

> I can hear the voices of
> > > those saying that there should be a 'natural' helper
> > > uuid_is_null(u8
> > > *) for the
> > > users that represent uuid as u8[16] (i.e. filesystems and sb-
> > > >s_uuid).
> > 
> > u8 * doesn't represent UUID as a type.
> > Perhaps we need to reflect this in the name of the function somehow.
> > 
> 
> OK, since you have no time nor the intention to convert filesystem
> code
> to use uuid_le 

uuid_be I suppose. I noticed core developers doesn't support endianess
feature of UUID: https://lkml.org/lkml/2016/5/25/724

That's also why I don't want to touch filesystem stuff.

> (not should you), I see 2 options for filesystems/VFS:
> 
> 1. Use the simple u8* libnvdimm helper proposed by this patch
> 2. Hoist uuid_t + helpers from fs/xfs/uuid.* to linux/uuid.h
> lib/uuid.c
> 
> If option #2 is preferred, I think we should conform to libuuid's
> helper
> name uuid_is_null() (instead of freebsd's uuid_is_nil()) 

I think option #2 is preferred and we need actually to submit some
generic uuid_{be|le}_cmp() helpers.

For now it's blocked by Gcc bug.

We may remove const from the prototypes for now and add them later when
the bug will be fixed.

> and maybe
> convert libnvdimm and bluetooth to use the xfs helpers as well.
> 
> Christoph,
> 
> Since you got me started on this helper, do you have a preference?

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy