Re: [PATCH] mkfs.xfs: Assign proper defaults to rmapbt and reflink flags

[Dave Chinner <david@fromorbit.com>]

On Wed, Apr 26, 2017 at 08:10:59AM -0700, Darrick J. Wong wrote:
> On Wed, Apr 26, 2017 at 09:02:44AM -0500, Eric Sandeen wrote:
> > The "defaultval" field in the options structure was a bit confusing,
> > so when the rmapbt & reflink options got added, the desire was
> > to keep them off by default, and "defaultval = 0" got set.
> > 
> > However, the purpose of this field is to define the default value
> > when the flag is specified with no associated value, i.e.
> > 
> > -m rmapbt vs. -m rmapbt=0 or -m rmapbt=1
> > 
> > Today, the resulting behavior is unexpected, and different from any
> > other mkfs flags; specifying "-m rmapbt,reflink" results in a
> > filesystem /without/ those features.
> > 
> > Fix these to be consistent with every other boolean flag in the
> > mkfs options, so that specifying the flag with no value will
> > enable the feature.
> > 
> > Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> 
> Someone should document that 'defaultval' is not the way to say
> 'disabled by default' in whatever the mkfs option processing code
> turns into.

....
 *   defaultval MANDATORY
 *     The value used if user specifies the subopt, but no value.
 *     If the subopt accepts some values (-d file=[1|0]), then this
 *     sets what is used with simple specifying the subopt (-d file).
 *     A special SUBOPT_NEEDS_VAL can be used to require a user-given
 *     value in any case.
 */
....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com