lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:	Mon, 16 Jan 2012 10:46:29 -0700
From:	Allison Henderson <achender@...ux.vnet.ibm.com>
To:	Dave Chinner <david@...morbit.com>
CC:	Lukas Czerner <lczerner@...hat.com>,
	Ext4 Developers List <linux-ext4@...r.kernel.org>,
	xfs@....sgi.com
Subject: Re: working on extent locks for i_mutex

On 01/15/2012 04:57 PM, Dave Chinner wrote:
> On Fri, Jan 13, 2012 at 01:50:52PM -0700, Allison Henderson wrote:
>> On 01/12/2012 09:34 PM, Dave Chinner wrote:
>>> On Thu, Jan 12, 2012 at 08:01:43PM -0700, Allison Henderson wrote:
>>>> Hi All,
>>>>
>>>> I know this is an old topic, but I am poking it again because I've
>>>> had some work items wrap up, and Im planning on picking up on this
>>>> one again.  I am thinking about implementing extent locks to replace
>>>> i_mutex.  So I just wanted to touch base with folks and see what
>>>> people are working on because I know there were some folks out there
>>>> that were thing about doing similar solutions.
>>>
>>> What locking API are you looking at? If you are looking at an
>>> something like:
>>>
>>> read_range_{try}lock(lock, off, len)
>>> read_range_unlock(lock, off, len)
>>> write_range_{try}lock(lock, off, len)
>>> write_range_unlock(lock, off, len)
>>>
>>> and implementing with an rbtree or a btree for tracking, then I
>>> definitely have a use for it in XFS - replacing the current rwsem
>>> that is used for the iolock. Range locks like this are the only
>>> thing we need to allow concurrent buffered writes to the same file
>>> to maintain the per-write exclusion that posix requires.
>>
>> Yes that is generally the idea I was thinking about doing, but at
>> the time, I was not thinking outside the scope of ext4.  You are
>> thinking maybe it should be in vfs layer so that it's something that
>> all the filesystems will use?  That seems to be the impression I'm
>> getting from folks.  Thx!
>
> Yes, that's what I'm suggesting. Not so much a vfs layer function,
> but a library (range locks could be useful outside filesystems) so
> locating it in lib/ was what I was thinking....
>
> Cheers,
>
> Dave.

Alrighty, that sounds good to me.  I will aim to keep it as general 
purpose as I can.  I am going to start some proto typing and will post 
back when I get something working.  Thx for the feedback all!  :)

Allison

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists