Re: [PATCH 2/2] fsx: add missing fallocate flag ifdefs

[Brian Foster <bfoster@redhat.com>]

On Thu, Sep 26, 2024 at 07:50:28AM -0700, Darrick J. Wong wrote:
> On Thu, Sep 26, 2024 at 10:41:47AM -0400, Brian Foster wrote:
> > The various fallocate flags are mostly ifdef'd for backward
> > compatibility with the exception of the associated test_fallocate()
> > calls to verify functionality at runtime. I suspect the reason for
> > this was to avoid ifdef ugliness around having to clear the runtime
> > flag for each operation, but unfortunately this defeats the purpose
> > of the ifdef protection everywhere else.
> > 
> > Factor out the fallocate related test calls into a new helper and
> > add the appropriate ifdefs.
> > 
> > Signed-off-by: Brian Foster <bfoster@redhat.com>
> > ---
> >  ltp/fsx.c | 59 ++++++++++++++++++++++++++++++++++++++++++-------------
> >  1 file changed, 45 insertions(+), 14 deletions(-)
> > 
> > diff --git a/ltp/fsx.c b/ltp/fsx.c
> > index 677f8c9f..417743c5 100644
> > --- a/ltp/fsx.c
> > +++ b/ltp/fsx.c
> > @@ -2833,6 +2833,50 @@ __test_fallocate(int mode, const char *mode_str)
> >  #endif
> >  }
> >  
> > +void
> > +test_fallocate_calls(void)
> > +{
> > +	if (fallocate_calls)
> > +		fallocate_calls = test_fallocate(0);
> > +	if (keep_size_calls)
> > +		keep_size_calls = test_fallocate(FALLOC_FL_KEEP_SIZE);
> > +
> > +#ifdef FALLOC_FL_UNSHARE_RANGE
> > +	if (unshare_range_calls)
> > +		unshare_range_calls = test_fallocate(FALLOC_FL_UNSHARE_RANGE);
> > +#else
> > +	unshare_range_calls = 0;
> > +#endif
> > +
> > +#ifdef FALLOC_FL_PUNCH_HOLE
> > +	if (punch_hole_calls)
> > +		punch_hole_calls = test_fallocate(FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE);
> > +#else
> > +	punch_hole_calls = 0;
> > +#endif
> > +
> > +#ifdef FALLOC_FL_ZERO_RANGE
> > +	if (zero_range_calls)
> > +		zero_range_calls = test_fallocate(FALLOC_FL_ZERO_RANGE);
> > +#else
> > +	zero_range_calls = 0;
> > +#endif
> > +
> > +#ifdef FALLOC_FL_COLLAPSE_RANGE
> > +	if (collapse_range_calls)
> > +		collapse_range_calls = test_fallocate(FALLOC_FL_COLLAPSE_RANGE);
> > +#else
> > +	collapse_range_calls = 0;
> > +#endif
> 
> The concept looks fine, but collapse and zero range have been in the
> kernel for a decade now, do we really need to have ifdef tests for them?
> 

Probably not.. but why even bother worrying about individual flags? The
insert and unshare flags have been around for 9 and 8 years
respectively, none of these were fully ifdef'd from the beginning, and
I'm not aware of anyone that has actually complained.

I'm not convinced that this patch matters for anybody in practice. I
included it just because it was simple enough to include the minimum
mechanical fix and I was slightly curious if somebody could come up with
a more elegant solution. In the spirit of being practical, maybe the
better approach here is to just remove the (at least the falloc flag
related) ifdefs entirely? We can always add them back if somebody
complains...

Brian

> --D
> 
> > +
> > +#ifdef FALLOC_FL_INSERT_RANGE
> > +	if (insert_range_calls)
> > +		insert_range_calls = test_fallocate(FALLOC_FL_INSERT_RANGE);
> > +#else
> > +	insert_range_calls = 0;
> > +#endif
> > +}
> > +
> >  bool
> >  keep_running(void)
> >  {
> > @@ -3271,20 +3315,7 @@ main(int argc, char **argv)
> >  		check_trunc_hack();
> >  	}
> >  
> > -	if (fallocate_calls)
> > -		fallocate_calls = test_fallocate(0);
> > -	if (keep_size_calls)
> > -		keep_size_calls = test_fallocate(FALLOC_FL_KEEP_SIZE);
> > -	if (unshare_range_calls)
> > -		unshare_range_calls = test_fallocate(FALLOC_FL_UNSHARE_RANGE);
> > -	if (punch_hole_calls)
> > -		punch_hole_calls = test_fallocate(FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE);
> > -	if (zero_range_calls)
> > -		zero_range_calls = test_fallocate(FALLOC_FL_ZERO_RANGE);
> > -	if (collapse_range_calls)
> > -		collapse_range_calls = test_fallocate(FALLOC_FL_COLLAPSE_RANGE);
> > -	if (insert_range_calls)
> > -		insert_range_calls = test_fallocate(FALLOC_FL_INSERT_RANGE);
> > +	test_fallocate_calls();
> >  	if (clone_range_calls)
> >  		clone_range_calls = test_clone_range();
> >  	if (dedupe_range_calls)
> > -- 
> > 2.46.1
> > 
> > 
>