From: Miklos Szeredi <miklos@szeredi.hu>
To: Ian Kent <raven@themaw.net>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tejun Heo <tj@kernel.org>, Eric Sandeen <sandeen@sandeen.net>,
Fox Chen <foxhlchen@gmail.com>,
Brice Goglin <brice.goglin@gmail.com>,
Al Viro <viro@zeniv.linux.org.uk>,
Rick Lindsley <ricklind@linux.vnet.ibm.com>,
David Howells <dhowells@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Carlos Maiolino <cmaiolino@redhat.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v7 2/6] kernfs: add a revision to identify directory node changes
Date: Wed, 16 Jun 2021 11:11:25 +0200 [thread overview]
Message-ID: <CAJfpegtgXvW+vyKQEvQauSXskYiO+GAjViDYo_84sa23eWCjdw@mail.gmail.com> (raw)
In-Reply-To: <162375276735.232295.14056277248741694521.stgit@web.messagingengine.com>
On Tue, 15 Jun 2021 at 12:26, Ian Kent <raven@themaw.net> wrote:
>
> Add a revision counter to kernfs directory nodes so it can be used
> to detect if a directory node has changed during negative dentry
> revalidation.
>
> There's an assumption that sizeof(unsigned long) <= sizeof(pointer)
> on all architectures and as far as I know that assumption holds.
>
> So adding a revision counter to the struct kernfs_elem_dir variant of
> the kernfs_node type union won't increase the size of the kernfs_node
> struct. This is because struct kernfs_elem_dir is at least
> sizeof(pointer) smaller than the largest union variant. It's tempting
> to make the revision counter a u64 but that would increase the size of
> kernfs_node on archs where sizeof(pointer) is smaller than the revision
> counter.
>
> Signed-off-by: Ian Kent <raven@themaw.net>
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
next prev parent reply other threads:[~2021-06-16 9:11 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-15 10:25 [PATCH v7 0/6] kernfs: proposed locking and concurrency improvement Ian Kent
2021-06-15 10:25 ` [PATCH v7 1/6] kernfs: move revalidate to be near lookup Ian Kent
2021-06-15 15:06 ` Greg Kroah-Hartman
2021-06-15 10:26 ` [PATCH v7 2/6] kernfs: add a revision to identify directory node changes Ian Kent
2021-06-16 9:11 ` Miklos Szeredi [this message]
2021-06-15 10:26 ` [PATCH v7 3/6] kernfs: use VFS negative dentry caching Ian Kent
2021-06-16 9:12 ` Miklos Szeredi
2021-06-15 10:26 ` [PATCH v7 4/6] kernfs: switch kernfs to use an rwsem Ian Kent
2021-06-15 10:26 ` [PATCH v7 5/6] kernfs: use i_lock to protect concurrent inode updates Ian Kent
2021-06-15 10:27 ` [PATCH v7 6/6] kernfs: dont call d_splice_alias() under kernfs node lock Ian Kent
2021-06-15 10:39 ` [PATCH v7 0/6] kernfs: proposed locking and concurrency improvement Ian Kent
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