Date: Sun, 20 Feb 2011 14:16:41 +0200
     From: [1]pagee...@freemail.hu
     On 19 Feb 2011 at 15:39, Dean Takemori wrote:

     But it's not clear to me what the "most correct" or most futureproof way
     to merge

     three moving targets (kernel, grsec and aufs2.1) together.

     Suggestions or comments anyone?

     PaX constifies the fields of struct address_space_operations to prevent
     exactly what
     aufs/etc want to do. obviously you can't have it both ways, something has
     to give ;).
     if you want aufs, revert this chunk in PaX.

   From: [2]sf...@users.sourceforge.net

   Date: February 20, 2011 3:24:36 AM HST

     Dean Takemori:

     Sources:

     linux-2.6.32.28

     grsecurity-2.2.1-2.6.32.28-201102121148.patch

     aufs2.1-32 (2011/02/14 standalone git snapshot)

     linux-2.6.32.28/fs/aufs/dynop.c: In function 'dy_aop':

     linux-2.6.32.28/fs/aufs/dynop.c:179:2: error: assignment of read-only
     member 'writepage'

     :::
     This looks similar to
     [3]http://www.mail-archive.com/aufs-users@lists.sourceforge.net/msg02644.h
     tml
     And there is a patch for it.
     [4]http://www.mail-archive.com/aufs-users@lists.sourceforge.net/msg02649.h
     tml
     While their versions are different from yours, I think this is what you
     should try first.

   Aha.  I think I understand the issue now.

   Loosely speaking, the PaX patch uses the compiler to prevent changes to

   filesystem structures that "ought not" to be changed.  On the other hand

   aufs is by design not an ordinary filesystem and performes some "magic"

   behind the scenes to make it appear ordinary to users.

   So the two projects are at odds in this area, and a code conflict is

   the result.

   The cleanest general solution I can see is if the PaX team would

   accept some sort of CONFIG_PAX_CONSTIFY_FS_H kernel config option with some

   appropriate ugliness

   #ifdef CONFIG_PAX_CONSTIFY_FS_H

   # define PAX_FS_H_CONST const

   #else

   # define PAX_FS_H_CONST

   #endif

   ...

   struct address_space_operations {

     int (* PAX_FS_H_CONST writepage)...

     ...

   But there may be plenty of reasons unobvious to me why such a thing

   would not be acceptable.

   Many thanks,

   -dean takemori

References

   1. mailto:pagee...@freemail.hu
   2. mailto:sf...@users.sourceforge.net
   3. http://www.mail-archive.com/aufs-users@lists.sourceforge.net/msg02644.html
   4. http://www.mail-archive.com/aufs-users@lists.sourceforge.net/msg02649.html
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