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

[Sidong Yang <realwakka@gmail.com>]

On Sun, Oct 31, 2021 at 07:28:17PM +0800, Qu Wenruo wrote:
> 
> 
> 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>

Hi, Qu.

Thanks for review!

> 
> 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.

Yes. I've checked do_balance() that it doesn't check START_NOWARN.
> 
> So can we handle it better for the warning in do_balance() other than
> cmd_balance_full() or cmd_balance_start()?

Totally agree. It would be better that it prints warning message in do_balance().
Also it's a way to simplify the logic.

> 
> And fully utilize the START_NOWARN flags?

I'll send you v2 soon.

Thanks,
Sidong
> 
> 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);
> >   	}
> >