NFSv4: Fix a state manager thread deadlock regression

Commit 4dc73c679114 reintroduces the deadlock that was fixed by commit
aeabb3c96186 ("NFSv4: Fix a NFSv4 state manager deadlock") because it
prevents the setup of new threads to handle reboot recovery, while the
older recovery thread is stuck returning delegations.

Fixes: 4dc73c679114 ("NFSv4: keep state manager thread active if swap is enabled")
Cc: stable@vger.kernel.org
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 3508d82..7016eaa 100644 (file)
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -10622,7 +10622,9 @@ static void nfs4_disable_swap(struct inode *inode)
         */
        struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 
-       nfs4_schedule_state_manager(clp);
+       set_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state);
+       clear_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state);
+       wake_up_var(&clp->cl_state);
 }
 
 static const struct inode_operations nfs4_dir_inode_operations = {

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 0bc160f..9a5d911 100644 (file)
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -1209,16 +1209,26 @@ void nfs4_schedule_state_manager(struct nfs_client *clp)
 {
        struct task_struct *task;
        char buf[INET6_ADDRSTRLEN + sizeof("-manager") + 1];
+       struct rpc_clnt *clnt = clp->cl_rpcclient;
+       bool swapon = false;
 
-       if (clp->cl_rpcclient->cl_shutdown)
+       if (clnt->cl_shutdown)
                return;
 
        set_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state);
-       if (test_and_set_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state) != 0) {
-               wake_up_var(&clp->cl_state);
-               return;
+
+       if (atomic_read(&clnt->cl_swapper)) {
+               swapon = !test_and_set_bit(NFS4CLNT_MANAGER_AVAILABLE,
+                                          &clp->cl_state);
+               if (!swapon) {
+                       wake_up_var(&clp->cl_state);
+                       return;
+               }
        }
-       set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state);
+
+       if (test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state) != 0)
+               return;
+
        __module_get(THIS_MODULE);
        refcount_inc(&clp->cl_count);
 
@@ -1235,8 +1245,9 @@ void nfs4_schedule_state_manager(struct nfs_client *clp)
                        __func__, PTR_ERR(task));
                if (!nfs_client_init_is_complete(clp))
                        nfs_mark_client_ready(clp, PTR_ERR(task));
+               if (swapon)
+                       clear_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state);
                nfs4_clear_state_manager_bit(clp);
-               clear_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state);
                nfs_put_client(clp);
                module_put(THIS_MODULE);
        }
@@ -2748,22 +2759,25 @@ static int nfs4_run_state_manager(void *ptr)
 
        allow_signal(SIGKILL);
 again:
-       set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state);
        nfs4_state_manager(clp);
-       if (atomic_read(&cl->cl_swapper)) {
+
+       if (test_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state) &&
+           !test_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state)) {
                wait_var_event_interruptible(&clp->cl_state,
                                             test_bit(NFS4CLNT_RUN_MANAGER,
                                                      &clp->cl_state));
-               if (atomic_read(&cl->cl_swapper) &&
-                   test_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state))
+               if (!atomic_read(&cl->cl_swapper))
+                       clear_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state);
+               if (refcount_read(&clp->cl_count) > 1 && !signalled() &&
+                   !test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state))
                        goto again;
                /* Either no longer a swapper, or were signalled */
+               clear_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state);
        }
-       clear_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state);
 
        if (refcount_read(&clp->cl_count) > 1 && !signalled() &&
            test_bit(NFS4CLNT_RUN_MANAGER, &clp->cl_state) &&
-           !test_and_set_bit(NFS4CLNT_MANAGER_AVAILABLE, &clp->cl_state))
+           !test_and_set_bit(NFS4CLNT_MANAGER_RUNNING, &clp->cl_state))
                goto again;
 
        nfs_put_client(clp);