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From:   "NeilBrown" <neilb@suse.de>
To:     "Wang Yugui" <wangyugui@e16-tech.com>
Cc:     "Christoph Hellwig" <hch@infradead.org>,
        "Josef Bacik" <josef@toxicpanda.com>,
        "J. Bruce Fields" <bfields@fieldses.org>,
        "Chuck Lever" <chuck.lever@oracle.com>, "Chris Mason" <clm@fb.com>,
        "David Sterba" <dsterba@suse.com>,
        "Alexander Viro" <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
        linux-btrfs@vger.kernel.org
Subject: Re: [PATCH/RFC 00/11] expose btrfs subvols in mount table correctly
In-reply-to: <20210728140431.D704.409509F4@e16-tech.com>
References: <162742539595.32498.13687924366155737575.stgit@noble.brown>,
 <20210728125819.6E52.409509F4@e16-tech.com>,
 <20210728140431.D704.409509F4@e16-tech.com>
Date:   Wed, 28 Jul 2021 17:01:10 +1000
Message-id: <162745567084.21659.16797059962461187633@noble.neil.brown.name>
Precedence: bulk

On Wed, 28 Jul 2021, Wang Yugui wrote:
> Hi,
> 
> This patchset works well in 5.14-rc3.

Thanks for testing.

> 
> 1, fixed dummy inode(255, BTRFS_FIRST_FREE_OBJECTID - 1 )  is changed to
> dynamic dummy inode(18446744073709551358, or 18446744073709551359, ...)

The BTRFS_FIRST_FREE_OBJECTID-1 was a just a hack, I never wanted it to
be permanent.
The new number is ULONG_MAX - subvol_id (where subvol_id starts at 257 I
think).
This is a bit less of a hack.  It is an easily available number that is
fairly unique.

> 
> 2, btrfs subvol mount info is shown in /proc/mounts, even if nfsd/nfs is
> not used.
> /dev/sdc                btrfs   94G  3.5M   93G   1% /mnt/test
> /dev/sdc                btrfs   94G  3.5M   93G   1% /mnt/test/sub1
> /dev/sdc                btrfs   94G  3.5M   93G   1% /mnt/test/sub2
> 
> This is a visiual feature change for btrfs user.

Hopefully it is an improvement.  But it is certainly a change that needs
to be carefully considered.

Thanks,
NeilBrown