Re: [PATCH 2/2] mkfs: Show progress during block discard

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

On Thu, Nov 21, 2019 at 10:44:45PM +0100, Pavel Reichl wrote:
> Signed-off-by: Pavel Reichl <preichl@redhat.com>
> ---
>  mkfs/xfs_mkfs.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
> index a02d6f66..07b8bd78 100644
> --- a/mkfs/xfs_mkfs.c
> +++ b/mkfs/xfs_mkfs.c
> @@ -1248,6 +1248,7 @@ discard_blocks(dev_t dev, uint64_t nsectors)
>  	const uint64_t	step		= (uint64_t)2<<30;
>  	/* Sector size is 512 bytes */
>  	const uint64_t	count		= nsectors << 9;
> +	uint64_t	prev_done	= (uint64_t) ~0;
>  
>  	fd = libxfs_device_to_fd(dev);
>  	if (fd <= 0)
> @@ -1255,6 +1256,7 @@ discard_blocks(dev_t dev, uint64_t nsectors)
>  
>  	while (offset < count) {
>  		uint64_t	tmp_step = step;
> +		uint64_t	done = offset * 100 / count;
>  
>  		if ((offset + step) > count)
>  			tmp_step = count - offset;
> @@ -1268,7 +1270,13 @@ discard_blocks(dev_t dev, uint64_t nsectors)
>  			return;
>  
>  		offset += tmp_step;
> +
> +		if (prev_done != done) {

Hmm... so this prints the status message every increase percentage
point, right?

> +			prev_done = done;
> +			fprintf(stderr, _("Discarding: %2lu%% done\n"), done);

This isn't an error, so why output to stderr?

FWIW if it's a tty you might consider ending that string with \r so the
status messages don't scroll off the screen.  Or possibly only reporting
status if stdout is a tty?

--D

> +		}
>  	}
> +	fprintf(stderr, _("Discarding is done.\n"));
>  }
>  
>  static __attribute__((noreturn)) void
> -- 
> 2.23.0
>