linux-kernel - Re: [PATCH 09/12] btrfs: change set_level() to bound the level passed in

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Message-ID: <20190205193254.GB24701@dennisz-mbp.dhcp.thefacebook.com>
Date:   Tue, 5 Feb 2019 14:32:54 -0500
From:   Dennis Zhou <dennis@...nel.org>
To:     David Sterba <dsterba@...e.cz>
Cc:     David Sterba <dsterba@...e.com>,
        Josef Bacik <josef@...icpanda.com>, Chris Mason <clm@...com>,
        Omar Sandoval <osandov@...ndov.com>,
        Nick Terrell <terrelln@...com>,
        Nikolay Borisov <nborisov@...e.com>, kernel-team@...com,
        linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 09/12] btrfs: change set_level() to bound the level
 passed in

On Tue, Feb 05, 2019 at 08:06:37PM +0100, David Sterba wrote:
> On Mon, Feb 04, 2019 at 03:20:05PM -0500, Dennis Zhou wrote:
> > -unsigned int btrfs_compress_str2level(const char *str)
> > +unsigned int btrfs_compress_str2level(unsigned int type, const char *str)
> >  {
> > -	if (strncmp(str, "zlib", 4) != 0)
> > +	unsigned int level;
> > +	int ret;
> > +
> > +	if (!type)
> >  		return 0;
> >  
> > -	/* Accepted form: zlib:1 up to zlib:9 and nothing left after the number */
> > -	if (str[4] == ':' && '1' <= str[5] && str[5] <= '9' && str[6] == 0)
> > -		return str[5] - '0';
> > +	if (str[0] == ':') {
> > +		ret = kstrtouint(str + 1, 10, &level);
> 
> The docs kstrtouint of say that initial + is also accepted, I'd rather
> keep the level specification strict, ie. no "zlib:+3" and no garbage
> after the number.
> 
> The validation is currently missing but I think we should catch levels
> out of range during mount/remount. The fallback to default is a safety
> but wrong specification should be communicated to the user early.

Ok. To make sure I understand properly for improper level (ie "30",
"+3", "+3d") set the level to default (already done) and pr_warn saying
invalid level?

Thanks,
Dennis