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Date:   Thu, 13 Jun 2019 10:12:34 -0400
From:   Josef Bacik <josef@toxicpanda.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>,
        Qu Wenruo <wqu@suse.com>, Nikolay Borisov <nborisov@suse.com>,
        linux-kernel@vger.kernel.org, Hannes Reinecke <hare@suse.com>,
        linux-fsdevel@vger.kernel.org,
        Damien Le Moal <damien.lemoal@wdc.com>,
        Matias =?utf-8?B?QmrDuHJsaW5n?= <mb@lightnvm.io>,
        Johannes Thumshirn <jthumshirn@suse.de>,
        Bart Van Assche <bvanassche@acm.org>
Subject: Re: [PATCH 09/19] btrfs: limit super block locations in HMZONED mode
Message-ID: <20190613141232.nud7gqz622ewcyzp@MacBook-Pro-91.local>
References: <20190607131025.31996-1-naohiro.aota@wdc.com>
 <20190607131025.31996-10-naohiro.aota@wdc.com>
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On Fri, Jun 07, 2019 at 10:10:15PM +0900, Naohiro Aota wrote:
> When in HMZONED mode, make sure that device super blocks are located in
> randomly writable zones of zoned block devices. That is, do not write super
> blocks in sequential write required zones of host-managed zoned block
> devices as update would not be possible.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
> Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
> ---
>  fs/btrfs/disk-io.c     | 11 +++++++++++
>  fs/btrfs/disk-io.h     |  1 +
>  fs/btrfs/extent-tree.c |  4 ++++
>  fs/btrfs/scrub.c       |  2 ++
>  4 files changed, 18 insertions(+)
> 
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 7c1404c76768..ddbb02906042 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3466,6 +3466,13 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
>  	return latest;
>  }
>  
> +int btrfs_check_super_location(struct btrfs_device *device, u64 pos)
> +{
> +	/* any address is good on a regular (zone_size == 0) device */
> +	/* non-SEQUENTIAL WRITE REQUIRED zones are capable on a zoned device */

This is not how you do multi-line comments in the kernel.  Thanks,

Josef