[PATCH 2/2 V2] mkfs.xfs: don't call blkid_get_topology on regular files

[Brian Foster]

On Thu, Jun 05, 2014 at 02:15:03PM -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 at redhat.com>
> ---
> 
> V2: Lose local "isa_file" flag, just switch based on 
> (xi->disfile) or (stat works & S_ISREG)
> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index 188b6b3..3b8bf67 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -456,9 +456,25 @@ static void get_topology(
>  	struct fs_topology	*ft,
>  	int			force_overwrite)
>  {
> -	if (!xi->disfile) {
> -		const char *dfile = xi->volname ? xi->volname : xi->dname;
> +	struct stat statbuf;
> +	char *dfile = xi->volname ? xi->volname : xi->dname;
>  
> +	/*
> +	 * Don't call blkid for topology if this is a "-d file" target, or
> +	 * if we've simply been pointed at a regular file.  platform_findsizes
> +	 * will attempt to find the underlying sector size of the host fs.
> +	 */
> +	if (xi->disfile ||
> +	    (!stat(dfile, &statbuf) && S_ISREG(statbuf.st_mode))) {
> +		int fd;
> +		long long dummy;
> +
> +		fd = open(dfile, O_RDONLY);
> +		if (fd >= 0) {
> +			platform_findsizes(dfile, fd, &dummy, &ft->lsectorsize);
> +			close(fd);
> +		}

The patch looks fine:

Reviewed-by: Brian Foster <bfoster at redhat.com>

It does look like we'd still be susceptible to error in a situation
where the file hasn't been created yet (which would occur in
libxfs_init()).

Brian

> +	} else {
>  		blkid_get_topology(dfile, &ft->dsunit, &ft->dswidth,
>  				   &ft->lsectorsize, &ft->psectorsize,
>  				   force_overwrite);
> 
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