[LU-4012] GSS upcall routine fails due to removed generic cache routines in Linux kernels >= 3.4.X

• Status: Resolved
• Project: Lustre
• Affects Version/s: Lustre 2.5.0
• Fix Version/s: Lustre 2.6.0
• Type: Bug
• Priority: Minor
• Reporter: Thomas Stibor
• Assignee: Nathaniel Clark
• Resolution: Fixed
• Labels: gssapi, kerberos, patch

Environment

Debian Wheezy with Lustre Patched Kernel 3.6.11

• Severity: 3

Description

With Linux kernel version >= 3.4.X the generic cache registering
routines cache_register(), cache_unregister() are removed.
This effects the GSS upcall routines for the Kerberos
support in Lustre. Before (Linux kernel <= 3.2.X) the
generic routines were coded as:

int cache_register(struct cache_detail *cd)
{
        return cache_register_net(cd, &init_net);
}
void cache_unregister(struct cache_detail *cd)
{
        cache_unregister_net(cd, &init_net);
}

To keep compatibility with former kernel versions,
cache_register_net() and cache_unregister_net() can
be applied instead, rather than the old and
removed cache_register() and cache_unregister().

I provide a patch to fix it.

Comments

[Peter Jones]

http://review.whamcloud.com/#/c/7770/

[Peter Jones]

Landed for 2.6

[James A Simmons]

Going through the GSS compile issue I get I noticed problems related to this patch. For RHEL6.4 kernels cache_register_net is not exported which causes this error:

WARNING: "cache_register_net" [/data/buildsystem/jsimmons-head/rpmbuild/BUILD/lustre-2.5.52/lustre/ptlrpc/gss/ptlrpc_gss.ko] undefined!
WARNING: "cache_unregister_net" [/data/buildsystem/jsimmons-head/rpmbuild/BUILD/lustre-2.5.52/lustre/ptlrpc/gss/ptlrpc_gss.ko] undefined!

[Thomas Stibor]

cache_register_net/cache_unregister_net was introducted in 2.6.37 and it not available in prior Kernel versions.

thomas@[SSH]denbp068:[1]~/linux/linux-stable/net/sunrpc>git checkout linux-2.6.36.y
Checking out files: 100% (41297/41297), done.
Switched to branch 'linux-2.6.36.y'
thomas@[SSH]denbp068:~/linux/linux-stable/net/sunrpc>grep -r "cache_register_net"
thomas@[SSH]denbp068:[1]~/linux/linux-stable/net/sunrpc>git checkout linux-2.6.37.y
Checking out files: 100% (11077/11077), done.
Switched to branch 'linux-2.6.37.y'
thomas@[SSH]denbp068:~/linux/linux-stable/net/sunrpc>grep -r "cache_register_net"
cache.c:int cache_register_net(struct cache_detail *cd, struct net *net)
cache.c:        return cache_register_net(cd, &init_net);
svcauth_unix.c: err = cache_register_net(cd, net);

Which Kernel version will be used in 2.6?
If RHEL6.4 (2.6.36-....) then we have provide compatibility.

Cheers
Thomas

[Peter Jones]

Thomas

atm 2.6 is currently targeted for RHEL6.5 (2.6.32-431.el6). Is cache_register_net/cache_unregister_net something that we could reasonably ask RH to include in an upcoming kernel update?

Peter

[Thomas Stibor]

Hello Peter,

I think for providing compatibility to RHEL6.5 (2.6.32-431.el6) it is most straightforward by using #ifdef check, e.g.
as follows

#
# cache_register/cache_unregister are removed since 3.4
#
AC_DEFUN([LC_HAVE_CACHE_REGISTER_NET],
[AC_MSG_CHECKING([if have cache_register_net])
LB_LINUX_TRY_COMPILE([
	#include <linux/sunrpc/cache.h>
],[
	cache_register_net(NULL, NULL);
],[
	AC_DEFINE(HAVE_CACHE_REGISTER_NET, 1,
		  [have cache_register_net])
	AC_MSG_RESULT([yes])
],[
	AC_MSG_RESULT([no])
])
])

I will provide a patch to fix this problem.

Cheers
Thomas