Re: [PATCH] btrfs-progs: balance: print warn mesg in old command

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

On 2021/10/31 10:21, Sidong Yang wrote:
> This patch makes old balance command to print warn mesg same as in start
> command. It makes a function that print warn mesg and commands use that
> function.
>
> Issue: #411
>
> Signed-off-by: Sidong Yang <realwakka@gmail.com>

The patch is indeed solving a problem, so good job.

But I found something weird which may worth some refactor before the fix.

> ---
>   cmds/balance.c | 37 ++++++++++++++++++++++---------------
>   1 file changed, 22 insertions(+), 15 deletions(-)
>
> diff --git a/cmds/balance.c b/cmds/balance.c
> index 7abc69d9..8d8db8a2 100644
> --- a/cmds/balance.c
> +++ b/cmds/balance.c
> @@ -303,6 +303,25 @@ enum {
>   	BALANCE_START_NOWARN  = 1 << 1

We have such flag for do_balance(), but it only checks START_FILTERS, no
check for START_NOWARN.

So can we handle it better for the warning in do_balance() other than
cmd_balance_full() or cmd_balance_start()?

And fully utilize the START_NOWARN flags?

Thanks,
Qu

>   };
>
> +static void print_start_warn_mesg()
> +{
> +	int delay = 10;
> +
> +	printf("WARNING:\n\n");
> +	printf("\tFull balance without filters requested. This operation is very\n");
> +	printf("\tintense and takes potentially very long. It is recommended to\n");
> +	printf("\tuse the balance filters to narrow down the scope of balance.\n");
> +	printf("\tUse 'btrfs balance start --full-balance' option to skip this\n");
> +	printf("\twarning. The operation will start in %d seconds.\n", delay);
> +	printf("\tUse Ctrl-C to stop it.\n");
> +	while (delay) {
> +		printf("%2d", delay--);
> +		fflush(stdout);
> +		sleep(1);
> +	}
> +	printf("\nStarting balance without any filters.\n");
> +}
> +
>   static int do_balance(const char *path, struct btrfs_ioctl_balance_args *args,
>   		      unsigned flags, bool enqueue)
>   {
> @@ -548,21 +567,7 @@ static int cmd_balance_start(const struct cmd_struct *cmd,
>   	}
>
>   	if (!(start_flags & BALANCE_START_FILTERS) && !(start_flags & BALANCE_START_NOWARN)) {
> -		int delay = 10;
> -
> -		printf("WARNING:\n\n");
> -		printf("\tFull balance without filters requested. This operation is very\n");
> -		printf("\tintense and takes potentially very long. It is recommended to\n");
> -		printf("\tuse the balance filters to narrow down the scope of balance.\n");
> -		printf("\tUse 'btrfs balance start --full-balance' option to skip this\n");
> -		printf("\twarning. The operation will start in %d seconds.\n", delay);
> -		printf("\tUse Ctrl-C to stop it.\n");
> -		while (delay) {
> -			printf("%2d", delay--);
> -			fflush(stdout);
> -			sleep(1);
> -		}
> -		printf("\nStarting balance without any filters.\n");
> +		print_start_warn_mesg();
>   	}
>
>   	if (force)
> @@ -886,6 +891,8 @@ static int cmd_balance(const struct cmd_struct *cmd, int argc, char **argv)
>   		memset(&args, 0, sizeof(args));
>   		args.flags |= BTRFS_BALANCE_TYPE_MASK;
>
> +		print_start_warn_mesg();
> +
>   		/* No enqueueing supported for the obsolete syntax */
>   		return do_balance(argv[1], &args, 0, false);
>   	}
>