From: Amir Goldstein <amir73il@gmail.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
Konstantin Khlebnikov <koct9i@gmail.com>,
linux-unionfs@vger.kernel.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [RFC][PATH 4/4] ovl: relax lock_rename when moving files between work and upper dir
Date: Fri, 11 Nov 2016 01:11:16 +0200 [thread overview]
Message-ID: <CAOQ4uxiW=FjRoAaumkjA=5b83rr3Cfu=Yk5nqsDx-qCenHGu3A@mail.gmail.com> (raw)
In-Reply-To: <20161110230557.GM19539@ZenIV.linux.org.uk>
On Fri, Nov 11, 2016 at 1:05 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Thu, Nov 10, 2016 at 11:02:21PM +0000, Al Viro wrote:
>> On Fri, Nov 11, 2016 at 12:44:43AM +0200, Amir Goldstein wrote:
>> > If work dir and upper dir have a common parent, then it
>> > is safe to move files between them without taking the super block
>> > s_vfs_rename_mutex.
>> >
>> > Since both upper dir and work dir (as well as $workdir/work)
>> > are delete locked on overlay mount, they cannot be moved.
>>
>> Do explain. What do you mean, "delete locked" and why exactly can't they
>> be moved?
>
That is explained in commit message of the first 2 patches, but
foremost I would like to say that the name "delete locked" is just the
best of all the bad choices for names I came up with, so I am expecting
better name suggestions.
The concept is to pin the entry so that it cannot be moved, so can have
certain guaranties about the stability of the directories topology.
> More specifically, what makes you think that may_delete() is called before
> any change of parent?
Because it is checked at the beginning of vfs_rename()
and in order to change a parent, an entry needs to be renamed. no?
What am I missing?
next prev parent reply other threads:[~2016-11-10 23:11 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-10 22:44 [RFC][PATH 0/4] Reduce excessive use of lock_rename() in overlayfs Amir Goldstein
2016-11-10 22:44 ` [RFC][PATH 1/4] vfs: reinterpret sillyrename flag as delete lock Amir Goldstein
2016-11-10 22:44 ` [RFC][PATH 2/4] vfs: introduce delete trylock/unlock Amir Goldstein
2016-11-10 22:44 ` [RFC][PATH 3/4] ovl: delete lock upper dir and work dir Amir Goldstein
2016-11-10 22:44 ` [RFC][PATH 4/4] ovl: relax lock_rename when moving files between work and upper dir Amir Goldstein
2016-11-10 23:02 ` Al Viro
2016-11-10 23:05 ` Al Viro
2016-11-10 23:11 ` Amir Goldstein [this message]
2016-11-10 23:17 ` Al Viro
2016-11-10 23:33 ` Amir Goldstein
2016-11-10 23:54 ` Al Viro
2016-11-11 0:11 ` Amir Goldstein
2016-11-11 0:27 ` Al Viro
2016-11-11 14:43 ` Amir Goldstein
2016-11-11 15:40 ` Al Viro
2016-11-11 16:17 ` Amir Goldstein
2016-11-11 17:27 ` Al Viro
2016-11-11 17:44 ` Miklos Szeredi
2017-01-12 5:42 ` Amir Goldstein
2017-01-12 10:00 ` Miklos Szeredi
2017-01-12 18:18 ` Amir Goldstein
2016-11-11 18:07 ` Amir Goldstein
2016-11-12 19:45 ` Amir Goldstein
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