NFSv4.1: Fix client id trunking on Linux

Currently, our trunking code will check for session trunking, but will
fail to detect client id trunking. This is a problem, because it means
that the client will fail to recognise that the two connections represent
shared state, even if they do not permit a shared session.
By removing the check for the server minor id, and only checking the
major id, we will end up doing the right thing in both cases: we close
down the new nfs_client and fall back to using the existing one.

Fixes: 05f4c350ee02e ("NFS: Discover NFSv4 server trunking when mounting")
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: stable@vger.kernel.org # 3.7.x
Tested-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 8 insertions, 9 deletions

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 03311259b0c4..d949d0f378ec 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -566,20 +566,14 @@ static bool nfs4_match_clientids(struct nfs_client *a, struct nfs_client *b)
 }
 
 /*
- * Returns true if the server owners match
+ * Returns true if the server major ids match
  */
 static bool
-nfs4_match_serverowners(struct nfs_client *a, struct nfs_client *b)
+nfs4_check_clientid_trunking(struct nfs_client *a, struct nfs_client *b)
 {
         struct nfs41_server_owner *o1 = a->cl_serverowner;
         struct nfs41_server_owner *o2 = b->cl_serverowner;
 
-        if (o1->minor_id != o2->minor_id) {
-                dprintk("NFS: --> %s server owner minor IDs do not match\n",
-                        __func__);
-                return false;
-        }
-
         if (o1->major_id_sz != o2->major_id_sz)
                 goto out_major_mismatch;
         if (memcmp(o1->major_id, o2->major_id, o1->major_id_sz) != 0)
@@ -654,7 +648,12 @@ int nfs41_walk_client_list(struct nfs_client *new,
                 if (!nfs4_match_clientids(pos, new))
                         continue;
 
-                if (!nfs4_match_serverowners(pos, new))
+                /*
+                 * Note that session trunking is just a special subcase of
+                 * client id trunking. In either case, we want to fall back
+                 * to using the existing nfs_client.
+                 */
+                if (!nfs4_check_clientid_trunking(pos, new))
                         continue;
 
                 atomic_inc(&pos->cl_count);