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:   Wed, 4 Sep 2019 16:12:35 -0700
From:   John Hubbard <>
To:     <>, Andrew Morton <>
CC:     Jason Gunthorpe <>,
        Dan Williams <>,
        Matthew Wilcox <>, Jan Kara <>,
        Theodore Ts'o <>, Michal Hocko <>,
        Dave Chinner <>,
        <>, <>,
        <>, <>,
        <>, <>,
Subject: Re: [RFC PATCH v2 02/19] fs/locks: Add Exclusive flag to user Layout

On 8/9/19 3:58 PM, wrote:
> From: Ira Weiny <>
> Add an exclusive lease flag which indicates that the layout mechanism
> can not be broken.

After studying the rest of these discussions extensively, I think in all
cases FL_EXCLUSIVE is better named "unbreakable", rather than exclusive.

If you read your sentence above, it basically reinforces that idea: "add an
exclusive flag to mean it is unbreakable" is a bit of a disconnect. It 
would be better to say,

Add an "unbreakable" lease flag which indicates that the layout lease
cannot be broken.

Furthermore, while this may or may not be a way forward on the "we cannot
have more than one process take a layout lease on a file/range", it at
least stops making it impossible. In other words, no one is going to
write a patch that allows sharing an exclusive layout lease--but someone
might well update some of these patches here to make it possible to
have multiple processes take unbreakable leases on the same file/range.

I haven't worked through everything there yet, but again:

* FL_UNBREAKABLE is the name you're looking for here, and

* I think we want to allow multiple processes to take FL_UNBREAKABLE
leases on the same file/range, so that we can make RDMA setups
reasonable. By "reasonable" I mean, "no need to have a lead process
that owns all the leases".

John Hubbard

Powered by blists - more mailing lists