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From: Ian Kent <raven@themaw.net>
To: Al Viro <viro@zeniv.linux.org.uk>
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>,
	Rick Lindsley <ricklind@linux.vnet.ibm.com>,
	David Howells <dhowells@redhat.com>,
	Miklos Szeredi <miklos@szeredi.hu>,
	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 3/7] kernfs: use VFS negative dentry caching
Date: Sun, 13 Jun 2021 09:57:10 +0800	[thread overview]
Message-ID: <8304e49310b16b865868982802bd2344d076c974.camel@themaw.net> (raw)
In-Reply-To: <YMQTMnfmOfdv2DpA@zeniv-ca.linux.org.uk>

On Sat, 2021-06-12 at 01:51 +0000, Al Viro wrote:
> On Sat, Jun 12, 2021 at 09:08:05AM +0800, Ian Kent wrote:
> 
> > But if I change to take the read lock to ensure there's no
> > operation
> > in progress for the revision check I would need the dget_parent(),
> > yes?
> 
> WTF for?  ->d_parent can change *ONLY* when ->d_lock is held on all
> dentries involved (including old and new parents).

Understood, thanks.

> 
> And it very definitely does *not* change for negative dentries.  I
> mean,
> look at the very beginning of __d_move().


  reply	other threads:[~2021-06-13  1:57 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
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 [this message]
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

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