NFSv4: Do not accept delegated opens when a delegation recall is in effect

...and report the servers that try to return a delegation when the client
is using the CLAIM_DELEG_CUR open mode. That behaviour is explicitly
forbidden in RFC3530.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 16 insertions, 8 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index be2bbac13817..d9f4d78c3413 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -39,6 +39,8 @@
 #include <linux/delay.h>
 #include <linux/errno.h>
 #include <linux/string.h>
+#include <linux/ratelimit.h>
+#include <linux/printk.h>
 #include <linux/slab.h>
 #include <linux/sunrpc/clnt.h>
 #include <linux/sunrpc/gss_api.h>
@@ -894,6 +896,8 @@ out:
 
 static int can_open_delegated(struct nfs_delegation *delegation, fmode_t fmode)
 {
+        if (delegation == NULL)
+                return 0;
         if ((delegation->type & fmode) != fmode)
                 return 0;
         if (test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags))
@@ -1036,8 +1040,7 @@ static struct nfs4_state *nfs4_try_open_cached(struct nfs4_opendata *opendata)
                 }
                 rcu_read_lock();
                 delegation = rcu_dereference(nfsi->delegation);
-                if (delegation == NULL ||
-                    !can_open_delegated(delegation, fmode)) {
+                if (!can_open_delegated(delegation, fmode)) {
                         rcu_read_unlock();
                         break;
                 }
@@ -1091,7 +1094,12 @@ static struct nfs4_state *nfs4_opendata_to_nfs4_state(struct nfs4_opendata *data
                 if (delegation)
                         delegation_flags = delegation->flags;
                 rcu_read_unlock();
-                if ((delegation_flags & 1UL<<NFS_DELEGATION_NEED_RECLAIM) == 0)
+                if (data->o_arg.claim == NFS4_OPEN_CLAIM_DELEGATE_CUR) {
+                        pr_err_ratelimited("NFS: Broken NFSv4 server %s is "
+                                        "returning a delegation for "
+                                        "OPEN(CLAIM_DELEGATE_CUR)\n",
+                                        NFS_CLIENT(inode)->cl_server);
+                } else if ((delegation_flags & 1UL<<NFS_DELEGATION_NEED_RECLAIM) == 0)
                         nfs_inode_set_delegation(state->inode,
                                         data->owner->so_cred,
                                         &data->o_res);
@@ -1423,11 +1431,9 @@ static void nfs4_open_prepare(struct rpc_task *task, void *calldata)
                         goto out_no_action;
                 rcu_read_lock();
                 delegation = rcu_dereference(NFS_I(data->state->inode)->delegation);
-                if (delegation != NULL &&
-                    test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags) == 0) {
-                        rcu_read_unlock();
-                        goto out_no_action;
-                }
+                if (data->o_arg.claim != NFS4_OPEN_CLAIM_DELEGATE_CUR &&
+                    can_open_delegated(delegation, data->o_arg.fmode))
+                        goto unlock_no_action;
                 rcu_read_unlock();
         }
         /* Update sequence id. */
@@ -1444,6 +1450,8 @@ static void nfs4_open_prepare(struct rpc_task *task, void *calldata)
                 return;
         rpc_call_start(task);
         return;
+unlock_no_action:
+        rcu_read_unlock();
 out_no_action:
         task->tk_action = NULL;