Re: [PATCH 1/2] Removed redundant if/else statement

[David Sterba <dsterba@suse.cz>]

On Fri, Feb 07, 2025 at 04:33:01AM +0200, Racz Zoltan wrote:
> Removed unnecesary if/else statement in the print_scrub_summary
> function. If unit_mode == UNITS_RAW, bytes_per_sec and limit get converted to
> UNITS_RAW, otherwise to unit_mode, but in both cases the exact same message is 
> written to the output
> 
>  cmds/scrub.c | 28 +++++++++-------------------
>  1 file changed, 9 insertions(+), 19 deletions(-)
> 
> diff --git a/cmds/scrub.c b/cmds/scrub.c
> index b2cdc924..3507c9d8 100644
> --- a/cmds/scrub.c
> +++ b/cmds/scrub.c
> @@ -207,25 +207,15 @@ static void print_scrub_summary(struct btrfs_scrub_progress *p, struct scrub_sta
>  	 * Rate and size units are disproportionate so they are affected only
>  	 * by --raw, otherwise it's human readable
>  	 */
> -	if (unit_mode == UNITS_RAW) {
> -		pr_verbose(LOG_DEFAULT, "Rate:             %s/s",
> -			pretty_size_mode(bytes_per_sec, UNITS_RAW));
> -		if (limit > 1)
> -			pr_verbose(LOG_DEFAULT, " (limit %s/s)",
> -				   pretty_size_mode(limit, UNITS_RAW));
> -		else if (limit == 1)
> -			pr_verbose(LOG_DEFAULT, " (some device limits set)");
> -		pr_verbose(LOG_DEFAULT, "\n");
> -	} else {
> -		pr_verbose(LOG_DEFAULT, "Rate:             %s/s",
> -			pretty_size_mode(bytes_per_sec, unit_mode));
> -		if (limit > 1)
> -			pr_verbose(LOG_DEFAULT, " (limit %s/s)",
> -				   pretty_size_mode(limit, unit_mode));
> -		else if (limit == 1)
> -			pr_verbose(LOG_DEFAULT, " (some device limits set)");
> -		pr_verbose(LOG_DEFAULT, "\n");
> -	}
> +	
> +	pr_verbose(LOG_DEFAULT, "Rate:             %s/s",
> +		pretty_size_mode(bytes_per_sec, unit_mode));
> +	if (limit > 1)
> +		pr_verbose(LOG_DEFAULT, " (limit %s/s)",
> +			pretty_size_mode(limit, unit_mode));
> +	else if (limit == 1)
> +		pr_verbose(LOG_DEFAULT, " (some device limits set)");
> +	pr_verbose(LOG_DEFAULT, "\n");

It's true that the branch is redundant and it's been like since the
first commit d60d48fce5d32a ("btrfs-progs: scrub status: add unit mode
options") where I added. The idea is to separate the other size options
from the rate, e.g. a 20TB sized device may not give more than 200MB/s
of rate and selecting --tbytes as size option will print number like
0.000MB/s

How it works now:

$ sudo btrfs scrub status /data
...
Total to scrub:   5.14TiB
Bytes scrubbed:   7.08GiB  (0.13%)
Rate:             207.07MiB/s
...


$ sudo btrfs scrub status --tbytes /data
...
Total to scrub:   5.14TiB
Bytes scrubbed:   0.00TiB  (0.09%)
Rate:             0.00TiB/s
...

but scrub is still running so the Rate is really not 0. The point is to
print sensible numbers for Rate regardless of the other options but with
the exception of --raw that will always print the raw numbers.

Digging in the log it seems it got broken in ec3c8428590e90
("btrfs-progs: scrub status: with --si, show rate in metric units"), the
fix should have been to add the SI modifier to the units, not forcing
the unit_mode from the command line.