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 v6 2/7] kernfs: add a revision to identify directory node changes
Date: Fri, 11 Jun 2021 14:49:43 +0200 [thread overview]
Message-ID: <CAJfpeguzPEy+UAcyT4tcpvYxeTwB+64yxRw8Sh7UBROBuafYdw@mail.gmail.com> (raw)
In-Reply-To: <162322859985.361452.14110524195807923374.stgit@web.messagingengine.com>
On Wed, 9 Jun 2021 at 10:50, 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>
> ---
> fs/kernfs/dir.c | 2 ++
> fs/kernfs/kernfs-internal.h | 23 +++++++++++++++++++++++
> include/linux/kernfs.h | 5 +++++
> 3 files changed, 30 insertions(+)
>
> diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
> index 33166ec90a112..b3d1bc0f317d0 100644
> --- a/fs/kernfs/dir.c
> +++ b/fs/kernfs/dir.c
> @@ -372,6 +372,7 @@ static int kernfs_link_sibling(struct kernfs_node *kn)
> /* successfully added, account subdir number */
> if (kernfs_type(kn) == KERNFS_DIR)
> kn->parent->dir.subdirs++;
> + kernfs_inc_rev(kn->parent);
>
> return 0;
> }
> @@ -394,6 +395,7 @@ static bool kernfs_unlink_sibling(struct kernfs_node *kn)
>
> if (kernfs_type(kn) == KERNFS_DIR)
> kn->parent->dir.subdirs--;
> + kernfs_inc_rev(kn->parent);
>
> rb_erase(&kn->rb, &kn->parent->dir.children);
> RB_CLEAR_NODE(&kn->rb);
> diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
> index ccc3b44f6306f..b4e7579e04799 100644
> --- a/fs/kernfs/kernfs-internal.h
> +++ b/fs/kernfs/kernfs-internal.h
> @@ -81,6 +81,29 @@ static inline struct kernfs_node *kernfs_dentry_node(struct dentry *dentry)
> return d_inode(dentry)->i_private;
> }
>
> +static inline void kernfs_set_rev(struct kernfs_node *kn,
> + struct dentry *dentry)
> +{
> + if (kernfs_type(kn) == KERNFS_DIR)
> + dentry->d_time = kn->dir.rev;
> +}
> +
> +static inline void kernfs_inc_rev(struct kernfs_node *kn)
> +{
> + if (kernfs_type(kn) == KERNFS_DIR)
> + kn->dir.rev++;
> +}
> +
> +static inline bool kernfs_dir_changed(struct kernfs_node *kn,
> + struct dentry *dentry)
> +{
> + if (kernfs_type(kn) == KERNFS_DIR) {
Aren't these always be called on a KERNFS_DIR node?
You could just reduce that to a WARN_ON, or remove the conditions
altogether then.
Thanks,
Miklos
next prev parent reply other threads:[~2021-06-11 12:51 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-09 8:49 [PATCH v6 0/7] kernfs: proposed locking and concurrency improvement Ian Kent
2021-06-09 8:49 ` [PATCH v6 1/7] kernfs: move revalidate to be near lookup Ian Kent
2021-06-11 12:45 ` Miklos Szeredi
2021-06-09 8:49 ` [PATCH v6 2/7] kernfs: add a revision to identify directory node changes Ian Kent
2021-06-11 12:49 ` Miklos Szeredi [this message]
2021-06-11 12:56 ` Ian Kent
2021-06-11 13:11 ` Greg Kroah-Hartman
2021-06-11 13:31 ` Ian Kent
2021-06-11 14:05 ` Greg Kroah-Hartman
2021-06-11 14:16 ` Ian Kent
2021-06-09 8:50 ` [PATCH v6 3/7] kernfs: use VFS negative dentry caching Ian Kent
2021-06-11 13:07 ` Miklos Szeredi
2021-06-12 0:47 ` Ian Kent
2021-06-12 1:48 ` Al Viro
2021-06-13 1:16 ` Ian Kent
2021-06-12 0:07 ` Al Viro
2021-06-12 0:43 ` Ian Kent
2021-06-12 1:08 ` Ian Kent
2021-06-12 1:51 ` Al Viro
2021-06-13 1:57 ` Ian Kent
2021-06-09 8:50 ` [PATCH v6 4/7] kernfs: switch kernfs to use an rwsem Ian Kent
2021-06-11 13:10 ` Miklos Szeredi
2021-06-12 1:24 ` Al Viro
2021-06-09 8:51 ` [PATCH v6 5/7] kernfs: use i_lock to protect concurrent inode updates Ian Kent
2021-06-11 13:11 ` Miklos Szeredi
2021-06-12 1:45 ` Al Viro
2021-06-13 1:31 ` Ian Kent
2021-06-14 1:32 ` Ian Kent
2021-06-14 6:52 ` Ian Kent
2021-06-14 7:16 ` Ian Kent
2021-06-09 8:52 ` [PATCH v6 6/7] kernfs: add kernfs_need_inode_refresh() Ian Kent
2021-06-11 13:13 ` Miklos Szeredi
2021-06-09 8:52 ` [PATCH v6 7/7] kernfs: dont call d_splice_alias() under kernfs node lock Ian Kent
2021-06-11 13:14 ` Miklos Szeredi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAJfpeguzPEy+UAcyT4tcpvYxeTwB+64yxRw8Sh7UBROBuafYdw@mail.gmail.com \
--to=miklos@szeredi.hu \
--cc=brice.goglin@gmail.com \
--cc=cmaiolino@redhat.com \
--cc=dhowells@redhat.com \
--cc=ebiederm@xmission.com \
--cc=foxhlchen@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mtosatti@redhat.com \
--cc=raven@themaw.net \
--cc=ricklind@linux.vnet.ibm.com \
--cc=sandeen@sandeen.net \
--cc=tj@kernel.org \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).