nfsd4: fix v4 state shutdown error paths

If someone tries to shut down the laundry_wq while it isn't up it'll
cause an oops.

This can happen because write_ports can create a nfsd_svc before we
really start the nfs server, and we may fail before the server is ever
started.

Also make sure state is shutdown on error paths in nfsd_svc().

Use a common global nfsd_up flag instead of nfs4_init, and create common
helper functions for nfsd start/shutdown, as there will be other work
that we want done only when we the number of nfsd threads transitions
between zero and nonzero.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

2 files changed, 43 insertions, 20 deletions

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 182448f7112..9cc3b786d56 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -51,7 +51,6 @@ static time_t boot_time;
 static u32 current_ownerid = 1;
 static u32 current_fileid = 1;
 static u32 current_delegid = 1;
-static u32 nfs4_init;
 static stateid_t zerostateid;             /* bits all 0 */
 static stateid_t onestateid;              /* bits all 1 */
 static u64 current_sessionid = 1;
@@ -4071,16 +4070,8 @@ out_free_laundry:
 int
 nfs4_state_start(void)
 {
-        int ret;
-
-        if (nfs4_init)
-                return 0;
         nfsd4_load_reboot_recovery_data();
-        ret = __nfs4_state_start();
-        if (ret)
-                return ret;
-        nfs4_init = 1;
-        return 0;
+        return __nfs4_state_start();
 }
 
 static void
@@ -4115,7 +4106,6 @@ __nfs4_state_shutdown(void)
         }
 
         nfsd4_shutdown_recdir();
-        nfs4_init = 0;
 }
 
 void
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 06b2a26edfe..d7a4d7b3744 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -180,6 +180,31 @@ int nfsd_nrthreads(void)
         return rv;
 }
 
+static bool nfsd_up = false;
+
+static int nfsd_startup(unsigned short port, int nrservs)
+{
+        int ret;
+
+        ret = nfs4_state_start();
+        nfsd_up = true;
+        return ret;
+}
+
+static void nfsd_shutdown(void)
+{
+        /*
+         * write_ports can create the server without actually starting
+         * any threads--if we get shut down before any threads are
+         * started, then nfsd_last_thread will be run before any of this
+         * other initialization has been done.
+         */
+        if (!nfsd_up)
+                return;
+        nfs4_state_shutdown();
+        nfsd_up = false;
+}
+
 static void nfsd_last_thread(struct svc_serv *serv)
 {
         /* When last nfsd thread exits we need to do some clean-up */
@@ -188,7 +213,7 @@ static void nfsd_last_thread(struct svc_serv *serv)
                 lockd_down();
         nfsd_serv = NULL;
         nfsd_racache_shutdown();
-        nfs4_state_shutdown();
+        nfsd_shutdown();
 
         printk(KERN_WARNING "nfsd: last server has exited, flushing export "
                             "cache\n");
@@ -380,6 +405,7 @@ int
 nfsd_svc(unsigned short port, int nrservs)
 {
         int     error;
+        bool    first_thread;
 
         mutex_lock(&nfsd_mutex);
         dprintk("nfsd: creating service\n");
@@ -395,19 +421,23 @@ nfsd_svc(unsigned short port, int nrservs)
         error = nfsd_racache_init(2*nrservs);
         if (error<0)
                 goto out;
-        error = nfs4_state_start();
-        if (error)
-                goto out;
+
+        first_thread = (nfsd_serv->sv_nrthreads == 0) && (nrservs != 0);
+
+        if (first_thread) {
+                error = nfsd_startup(port, nrservs);
+                if (error)
+                        goto out;
+        }
 
         nfsd_reset_versions();
 
         error = nfsd_create_serv();
-
         if (error)
-                goto out;
+                goto out_shutdown;
         error = nfsd_init_socks(port);
         if (error)
-                goto failure;
+                goto out_destroy;
 
         error = svc_set_num_threads(nfsd_serv, NULL, nrservs);
         if (error == 0)
@@ -416,9 +446,12 @@ nfsd_svc(unsigned short port, int nrservs)
                  * so subtract 1
                  */
                 error = nfsd_serv->sv_nrthreads - 1;
- failure:
+out_destroy:
         svc_destroy(nfsd_serv);         /* Release server */
- out:
+out_shutdown:
+        if (error < 0 && first_thread)
+                nfsd_shutdown();
+out:
         mutex_unlock(&nfsd_mutex);
         return error;
 }