linux-ext4 - Re: [PATCH] ext4: introduce per-inode DAX flag

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 linux-hardening linux-cve-announce 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]

Message-ID: <20170825162837.urica6l4eamu356w@thunk.org>
Date:   Fri, 25 Aug 2017 12:28:37 -0400
From:   Theodore Ts'o <tytso@....edu>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     linux-ext4@...r.kernel.org, Lukas Czerner <lczerner@...hat.com>,
        linux-xfs@...r.kernel.org
Subject: Re: [PATCH] ext4: introduce per-inode DAX flag

On Fri, Aug 25, 2017 at 08:40:32AM -0700, Christoph Hellwig wrote:
> On Fri, Aug 25, 2017 at 11:14:45AM -0400, Theodore Ts'o wrote:
> > > I don't know of anyone that actually uses the flag.  If someone did
> > > that would probably run into problems like changing that changing it
> > > on a file that's currently mmaped would crash an burn badly.
> > 
> > Crash and burn meaning the *kernel* will crash and burn?  Or will data
> > be damaged?
> > 
> > Given that, maybe XFS should withdraw support for the DAX and hope no
> > one is actually using it?
> 
> Nah, -o dax works very well.  It's just the flag instead of the -o dax
> option or rather switching it on a mapped file will probably be very dangerous.

Sorry, I was suggested XFS withdrawing support for the pre-file dax
flag.  I thought part of the argument for why ext4 should accept this
patch is that XFS already has the per-file DAX flag?

      	      	  	      	  	   - Ted