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Date:   Thu, 31 Aug 2023 07:31:08 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Christoph Hellwig <hch@lst.de>
Cc:     Christian Brauner <brauner@kernel.org>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Paul Moore <paul@paul-moore.com>,
        Stephen Smalley <stephen.smalley.work@gmail.com>,
        Eric Paris <eparis@parisplace.org>, linux-s390@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, selinux@vger.kernel.org
Subject: Re: [PATCH 2/4] devpts: free sb->s_fs_info after shutting down the
 super block
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 <20230831053157.256319-3-hch@lst.de>
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On Thu, Aug 31, 2023 at 07:31:55AM +0200, Christoph Hellwig wrote:
> sb->s_fs_info can only be safely freed after generic_shutdown_super was
> called and all access to the super_block has stopped.

Similar to ramfs case; nothing in dentry/inode eviction codepaths is
using anything in ->s_fs_info.  And references in tty are holding
an active ref to superblock in question, preventing ->kill_sb(), so
nothing from the outside is going to play with e.g. devpts_{new,kill}_index()
under us.