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  PHC 
Open Source and information security mailing list archives
Hash Suite for Android: free password hash cracker in your pocket
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Thu, 27 Sep 2018 10:27:38 -0400
From:   "Theodore Y. Ts'o" <>
To:     Jeff Layton <>
Cc:     Alan Cox <>,
        焦晓冬 <>,,,
        Rogier Wolff <>,
        Matthew Wilcox <>
Subject: Re: POSIX violation by writeback error

On Thu, Sep 27, 2018 at 08:43:10AM -0400, Jeff Layton wrote:
> Basically, the problem (as I see it) is that we can end up evicting
> uncleanable data from the cache before you have a chance to call fsync,
> and that means that the results of a read after a write are not
> completely reliable.

Part of the problem is that people don't agree on what the problem is.  :-)

The original posting was from someone who claimed it was a "POSIX
violation" if a subsequent read returns *successfully*, but then the
writeback succeeds.

Other people are worried about this problem; yet others are worried
about the system wedging and OOM-killing itself, etc.

The problem is that in the face of I/O errors, it's impossible to keep
everyone happy.  (You could make the local storage device completely
reliable, with a multi-million dollar storage array with remote
replication, but then the CFO won't be happy; and other people were
talking about making things work with cheap USB thumb drives and
laptops.  This is the very definition of an over-constained problem.)

       	      	   	      	    		    - Ted

Powered by blists - more mailing lists