Re: [PATCH 2/2, RFC] mkfs.xfs: don't call blkid_get_topology on regular files

[Christoph Hellwig <hch@xxxxxxxxxxxxx>]

On Tue, May 27, 2014 at 07:15:20PM -0500, Eric Sandeen wrote:
> If we encounter a target that's really a regular file,
> even without "-d file..." on the cmdline, call
> platform_findsizes() instead of blkid_get_topology to
> try to discover the "sector size" via the fsgeom() call.
> 
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index 37c05a9..74180c9 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -454,12 +454,26 @@ static void get_topology(
>       struct fs_topology      *ft,
>       int                     force_overwrite)
>  {
> -     if (!xi->disfile) {
> -             const char *dfile = xi->volname ? xi->volname : xi->dname;
> +     int is_a_file = 0;
> +     struct stat statbuf;
> +     char *dfile = xi->volname ? xi->volname : xi->dname;
>  
> +     if (!stat(dfile, &statbuf) && S_ISREG(statbuf.st_mode))
> +             is_a_file = 1;
> +
> +     if (!xi->disfile && !is_a_file) {

Why do need both xi->disfile and a local flag/  Why do we do the
that even if xi->disfile is set?