Re: [PATCH] libblkid: implement zone-aware probing for HMZONED btrfs

From: Karel Zak <kzak@redhat.com>
To: Naohiro Aota <naohiro.aota@wdc.com>
Cc: linux-btrfs@vger.kernel.org, David Sterba <dsterba@suse.com>,
	Chris Mason <clm@fb.com>, Josef Bacik <josef@toxicpanda.com>,
	Nikolay Borisov <nborisov@suse.com>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	Johannes Thumshirn <jthumshirn@suse.de>,
	Hannes Reinecke <hare@suse.com>,
	Anand Jain <anand.jain@oracle.com>,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] libblkid: implement zone-aware probing for HMZONED btrfs
Date: Thu, 5 Dec 2019 15:51:02 +0100	[thread overview]
Message-ID: <20191205145102.omyoq6nn5qnximxr@10.255.255.10> (raw)
In-Reply-To: <20191204083023.861495-1-naohiro.aota@wdc.com>

On Wed, Dec 04, 2019 at 05:30:23PM +0900, Naohiro Aota wrote:
>  	while(mag && mag->magic) {
>  		unsigned char *buf;
> -
> -		off = (mag->kboff + (mag->sboff >> 10)) << 10;
> +		uint64_t kboff;
> +
> +		if (!mag->is_zone)
> +			kboff = mag->kboff;
> +		else {
> +			uint32_t zone_size_sector;
> +			int ret;
> +
> +			ret = ioctl(pr->fd, BLKGETZONESZ, &zone_size_sector);

I guess this ioctl returns always the same number, right? 

If yes, than you don't want to call it always when libmount compares
any magic string. It would be better call it only once from
blkid_probe_set_device() and save zone_size_sector to struct
blkid_probe.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com