Re: [RFC][PATCH 3/4] sunrpc: Improve UTS namespace workaround
From: Chuck Lever
Date: Tue Jan 06 2009 - 11:03:22 EST
Matt-
Thanks for pursuing a permanent fix for this.
On Jan 5, 2009, at Jan 5, 2009, 8:13 PM, Matt Helsley wrote:
We can improve upon a workaround applied in commit
63ffc23d307c9534c732edd87895e37b223004a3 ( http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=63ffc23d307c9534c732edd87895e37b223004a3
)
The original problem was:
"On a system with nfs mounts, if a task unshares its mount namespace,
a oops can occur when the system is rebooted if the task is the last
to unreference the nfs mount. It will try to create a rpc request
using utsname() which has been invalidated by free_nsproxy()."
Cedric worked around this by always using the initial uts namespace
for RPC.
Critically this workaround meant that RPC clients in uts namespaces
can never
report the changed nodename when utilizing RPC.
Fix that by storing the nodename in the NFS server structure (part
of the NFS
super block) and, when an RPC client is operating on behalf of NFS,
reporting
that nodename. This solves the problem for NFS clients but leaves
any other
RPC users out in the cold.
Rather than caching the nodename in the client structure RPC should
obtain the
nodename from RPC callers. It would then be up to those services
making RPC
calls to cache the nodename for as long as necessary -- somewhat
like this patch
does with NFS.
Instead of having the RPC client call the consumer back, why can't you
pass the nodename as an argument to each RPC call; say, via the
rpc_message structure?
NOTE: Part of Cedric's workaround -- use of the initial uts
namespace -- is
still necessary because non-NFS RPC callers still rely on the
nodename cached
with the RPC client struct.
In the long run I think it would be more useful to spell out where
each consumer gets its nodename value, rather than having a convenient
default value. A default would encourage exposing nodenames
inappropriately due to sloppy coding and incorrect assumptions (on the
developer's part) about a complex API.
Where would NFSv4 callbacks get a nodename, for example? And what
about rpcbind requests?
Thoughts?
More comments below.
Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx>
Cc: Cedric Le Goater <clg@xxxxxxxxxx>
Cc: Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>
Cc: linux-nfs@xxxxxxxxxxxxxxx
Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxx>
Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
Cc: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Linux Containers <containers@xxxxxxxxxxxxxx>
---
fs/lockd/clntproc.c | 16 +++++++++++++---
fs/nfs/client.c | 6 ++++++
fs/nfs/super.c | 6 ++++++
include/linux/nfs_fs.h | 2 ++
include/linux/nfs_fs_sb.h | 3 +++
include/linux/sunrpc/clnt.h | 2 ++
net/sunrpc/auth_unix.c | 13 ++++++++++++-
7 files changed, 44 insertions(+), 4 deletions(-)
Index: linux-2.6.28/include/linux/sunrpc/clnt.h
===================================================================
--- linux-2.6.28.orig/include/linux/sunrpc/clnt.h
+++ linux-2.6.28/include/linux/sunrpc/clnt.h
@@ -19,6 +19,7 @@
#include <asm/signal.h>
struct rpc_inode;
+struct nfs_server;
/*
* The high-level client handle
@@ -50,6 +51,7 @@ struct rpc_clnt {
int cl_nodelen; /* nodename length */
char cl_nodename[UNX_MAXNODENAME];
+ struct nfs_server *cl_nfs_server;
This is a layering violation... I would rather avoid introducing new
strong data structure dependencies on one of RPC's consumers.
char cl_pathname[30];/* Path in rpc_pipe_fs */
struct vfsmount * cl_vfsmnt;
struct dentry * cl_dentry; /* inode */
Index: linux-2.6.28/net/sunrpc/auth_unix.c
===================================================================
--- linux-2.6.28.orig/net/sunrpc/auth_unix.c
+++ linux-2.6.28/net/sunrpc/auth_unix.c
@@ -12,6 +12,13 @@
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/auth.h>
+#include <linux/nfs.h>
+#include <linux/nfs2.h>
+#include <linux/nfs3.h>
+#include <linux/nfs4.h>
+#include <linux/nfs_xdr.h>
+#include <linux/nfs_fs_sb.h>
+
#define NFS_NGROUPS 16
struct unx_cred {
@@ -151,7 +158,11 @@ unx_marshal(struct rpc_task *task, __be3
/*
* Copy the UTS nodename captured when the client was created.
*/
- p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
+ if (clnt->cl_nfs_server)
+ p = xdr_encode_array(p, clnt->cl_nfs_server->nodename,
+ clnt->cl_nfs_server->nodelen);
+ else
+ p = xdr_encode_array(p, clnt->cl_nodename, clnt->cl_nodelen);
*p++ = htonl((u32) cred->uc_uid);
*p++ = htonl((u32) cred->uc_gid);
Index: linux-2.6.28/include/linux/nfs_fs_sb.h
===================================================================
--- linux-2.6.28.orig/include/linux/nfs_fs_sb.h
+++ linux-2.6.28/include/linux/nfs_fs_sb.h
@@ -126,6 +126,9 @@ struct nfs_server {
u32 mountd_version;
unsigned short mountd_port;
unsigned short mountd_protocol;
+
+ int nodelen; /* nodename length */
+ char nodename[UNX_MAXNODENAME];
};
/* Server capabilities */
Index: linux-2.6.28/fs/nfs/super.c
===================================================================
--- linux-2.6.28.orig/fs/nfs/super.c
+++ linux-2.6.28/fs/nfs/super.c
@@ -51,6 +51,7 @@
#include <linux/nfs_xdr.h>
#include <linux/magic.h>
#include <linux/parser.h>
+#include <linux/utsname.h>
#include <asm/system.h>
#include <asm/uaccess.h>
@@ -1830,6 +1831,11 @@ static void nfs_fill_super(struct super_
sb->s_time_gran = 1;
}
+ server->nodelen = strlen(utsname()->nodename);
+ if (server->nodelen > UNX_MAXNODENAME)
+ server->nodelen = UNX_MAXNODENAME;
+ memcpy(server->nodename, utsname()->nodename, server->nodelen);
+
sb->s_op = &nfs_sops;
nfs_initialise_sb(sb);
}
Index: linux-2.6.28/fs/nfs/client.c
===================================================================
--- linux-2.6.28.orig/fs/nfs/client.c
+++ linux-2.6.28/fs/nfs/client.c
@@ -25,10 +25,12 @@
#include <linux/sunrpc/metrics.h>
#include <linux/sunrpc/xprtsock.h>
#include <linux/sunrpc/xprtrdma.h>
+#include <linux/sunrpc/svc.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_mount.h>
#include <linux/nfs4_mount.h>
#include <linux/lockd/bind.h>
+#include <linux/lockd/lockd.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/nfs_idmap.h>
@@ -47,6 +49,7 @@
#include "internal.h"
#define NFSDBG_FACILITY NFSDBG_CLIENT
+#define NLMDBG_FACILITY NLMDBG_CLIENT
static DEFINE_SPINLOCK(nfs_client_lock);
static LIST_HEAD(nfs_client_list);
@@ -555,6 +558,7 @@ static void nfs_init_server_aclclient(st
/* No errors! Assume that Sun nfsacls are supported */
server->caps |= NFS_CAP_ACLS;
+ server->client_acl->cl_nfs_server = server;
return;
out_noacl:
@@ -673,6 +677,7 @@ static int nfs_init_server(struct nfs_se
goto error;
server->nfs_client = clp;
+ clp->cl_rpcclient->cl_nfs_server = server;
/* Initialise the client representation from the mount data */
server->flags = data->flags;
@@ -1035,6 +1040,7 @@ static int nfs4_set_client(struct nfs_se
goto error_put;
server->nfs_client = clp;
+ clp->cl_rpcclient->cl_nfs_server = server;
dprintk("<-- nfs4_set_client() = 0 [new %p]\n", clp);
return 0;
Index: linux-2.6.28/fs/lockd/clntproc.c
===================================================================
--- linux-2.6.28.orig/fs/lockd/clntproc.c
+++ linux-2.6.28/fs/lockd/clntproc.c
@@ -10,8 +10,8 @@
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
+#include <linux/mount.h>
#include <linux/nfs_fs.h>
-#include <linux/utsname.h>
#include <linux/freezer.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
@@ -118,6 +118,11 @@ static struct nlm_lockowner *nlm_find_lo
return res;
}
+struct nfs_server *fl_nfs_server(struct file_lock *fl)
+{
+ return NFS_SB(fl->fl_file->f_path.mnt->mnt_sb);
+}
+
/*
* Initialize arguments for TEST/LOCK/UNLOCK/CANCEL calls
*/
@@ -125,15 +130,18 @@ static void nlmclnt_setlockargs(struct n
{
struct nlm_args *argp = &req->a_args;
struct nlm_lock *lock = &argp->lock;
+ char *nodename;
nlmclnt_next_cookie(&argp->cookie);
argp->state = nsm_local_state;
memcpy(&lock->fh, NFS_FH(fl->fl_file->f_path.dentry->d_inode),
sizeof(struct nfs_fh));
- lock->caller = utsname()->nodename;
+
+ nodename = fl_nfs_server(fl)->nodename;
+ lock->caller = nodename;
lock->oh.data = req->a_owner;
lock->oh.len = snprintf(req->a_owner, sizeof(req->a_owner), "%u@%s",
(unsigned int)fl->fl_u.nfs_fl.owner->pid,
- utsname()->nodename);
+ nodename);
lock->svid = fl->fl_u.nfs_fl.owner->pid;
lock->fl.fl_start = fl->fl_start;
lock->fl.fl_end = fl->fl_end;
@@ -272,6 +280,7 @@ nlmclnt_call(struct rpc_cred *cred, stru
/* If we have no RPC client yet, create one. */
if ((clnt = nlm_bind_host(host)) == NULL)
return -ENOLCK;
+ clnt->cl_nfs_server = fl_nfs_server(&argp->lock.fl);
msg.rpc_proc = &clnt->cl_procinfo[proc];
/* Perform the RPC call. If an error occurs, try again */
@@ -344,6 +353,7 @@ static struct rpc_task *__nlm_async_call
clnt = nlm_bind_host(host);
if (clnt == NULL)
goto out_err;
+ clnt->cl_nfs_server = fl_nfs_server(&req->a_args.lock.fl);
This change takes care of fixing NFS client locking requests, but the
NFS server also makes lockd callbacks to the client. You won't have
an nfs_server handle on the NFS server side.
Generally, you ought to pass just the nodename where needed, not a
pointer to the nfs_server.
msg->rpc_proc = &clnt->cl_procinfo[proc];
task_setup_data.rpc_client = clnt;
Index: linux-2.6.28/include/linux/nfs_fs.h
===================================================================
--- linux-2.6.28.orig/include/linux/nfs_fs.h
+++ linux-2.6.28/include/linux/nfs_fs.h
@@ -262,6 +262,8 @@ static inline __u64 NFS_FILEID(const str
return NFS_I(inode)->fileid;
}
+struct nfs_server *fl_nfs_server(struct file_lock *fl);
+
static inline void set_nfs_fileid(struct inode *inode, __u64 fileid)
{
NFS_I(inode)->fileid = fileid;
--
--
Chuck Lever
chuck[dot]lever[at]oracle[dot]com
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