Re: [PATCH] duperemove: test presence of dedupe ioctl

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

On Wed, Dec 14, 2016 at 11:26:07AM -0800, Christoph Hellwig wrote:
> On Wed, Dec 14, 2016 at 10:38:45AM -0800, Darrick J. Wong wrote:
> > > > +struct fake_btrfs_ioctl_same_args {
> > > > +	struct btrfs_ioctl_same_args args;
> > > > +	struct btrfs_ioctl_same_extent_info info;
> > > > +};
> > > 
> > > Why does this need a fake structure here?
> > 
> > In order to test the ioctl we have to fill out at least one
> > btrfs_ioctl_same_extent_info so that we get far enough into the fs-specific
> > dedupe_range handler that we've verified that the fs is capable of dedupe and
> > that the fs is willing to try to satisfy the request.
> 
> Oh, got it, it's just the fake that tripped me up.
> 
> > We could just malloc sizeof(_same_args) + sizeof(_same_extent_info)...
> 
> Either that, or more simply just don't give the structure a name
> by just declaring it locally on the stack:
> 
> 	struct {
> 		struct btrfs_ioctl_same_args args;
> 		struct btrfs_ioctl_same_extent_info info;
> 	} sa = { 0 };

Fair enough, no need to pollute the namespace.

--D

> 
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