1 files changed, 76 insertions, 72 deletions

diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 941041f4b136..80292ff5e924 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -21,6 +21,7 @@
 #include <linux/smp_lock.h>
 #include <linux/freezer.h>
 #include <linux/fs_struct.h>
+#include <linux/kthread.h>
 
 #include <linux/sunrpc/types.h>
 #include <linux/sunrpc/stats.h>
@@ -36,28 +37,38 @@
 
 #define NFSDDBG_FACILITY        NFSDDBG_SVC
 
-/* these signals will be delivered to an nfsd thread 
- * when handling a request
- */
-#define ALLOWED_SIGS    (sigmask(SIGKILL))
-/* these signals will be delivered to an nfsd thread
- * when not handling a request. i.e. when waiting
- */
-#define SHUTDOWN_SIGS   (sigmask(SIGKILL) | sigmask(SIGHUP) | sigmask(SIGINT) | sigmask(SIGQUIT))
-/* if the last thread dies with SIGHUP, then the exports table is
- * left unchanged ( like 2.4-{0-9} ).  Any other signal will clear
- * the exports table (like 2.2).
- */
-#define SIG_NOCLEAN     SIGHUP
-
 extern struct svc_program       nfsd_program;
-static void                     nfsd(struct svc_rqst *rqstp);
+static int                      nfsd(void *vrqstp);
 struct timeval                  nfssvc_boot;
-       struct svc_serv          *nfsd_serv;
 static atomic_t                 nfsd_busy;
 static unsigned long            nfsd_last_call;
 static DEFINE_SPINLOCK(nfsd_call_lock);
 
+/*
+ * nfsd_mutex protects nfsd_serv -- both the pointer itself and the members
+ * of the svc_serv struct. In particular, ->sv_nrthreads but also to some
+ * extent ->sv_temp_socks and ->sv_permsocks. It also protects nfsdstats.th_cnt
+ *
+ * If (out side the lock) nfsd_serv is non-NULL, then it must point to a
+ * properly initialised 'struct svc_serv' with ->sv_nrthreads > 0. That number
+ * of nfsd threads must exist and each must listed in ->sp_all_threads in each
+ * entry of ->sv_pools[].
+ *
+ * Transitions of the thread count between zero and non-zero are of particular
+ * interest since the svc_serv needs to be created and initialized at that
+ * point, or freed.
+ *
+ * Finally, the nfsd_mutex also protects some of the global variables that are
+ * accessed when nfsd starts and that are settable via the write_* routines in
+ * nfsctl.c. In particular:
+ *
+ *      user_recovery_dirname
+ *      user_lease_time
+ *      nfsd_versions
+ */
+DEFINE_MUTEX(nfsd_mutex);
+struct svc_serv                 *nfsd_serv;
+
 #if defined(CONFIG_NFSD_V2_ACL) || defined(CONFIG_NFSD_V3_ACL)
 static struct svc_stat  nfsd_acl_svcstats;
 static struct svc_version *     nfsd_acl_version[] = {
@@ -145,13 +156,14 @@ int nfsd_vers(int vers, enum vers_op change)
 
 int nfsd_nrthreads(void)
 {
-        if (nfsd_serv == NULL)
-                return 0;
-        else
-                return nfsd_serv->sv_nrthreads;
+        int rv = 0;
+        mutex_lock(&nfsd_mutex);
+        if (nfsd_serv)
+                rv = nfsd_serv->sv_nrthreads;
+        mutex_unlock(&nfsd_mutex);
+        return rv;
 }
 
-static int killsig;     /* signal that was used to kill last nfsd */
 static void nfsd_last_thread(struct svc_serv *serv)
 {
         /* When last nfsd thread exits we need to do some clean-up */
@@ -162,11 +174,9 @@ static void nfsd_last_thread(struct svc_serv *serv)
         nfsd_racache_shutdown();
         nfs4_state_shutdown();
 
-        printk(KERN_WARNING "nfsd: last server has exited\n");
-        if (killsig != SIG_NOCLEAN) {
-                printk(KERN_WARNING "nfsd: unexporting all filesystems\n");
-                nfsd_export_flush();
-        }
+        printk(KERN_WARNING "nfsd: last server has exited, flushing export "
+                            "cache\n");
+        nfsd_export_flush();
 }
 
 void nfsd_reset_versions(void)
@@ -190,13 +200,14 @@ void nfsd_reset_versions(void)
         }
 }
 
+
 int nfsd_create_serv(void)
 {
         int err = 0;
-        lock_kernel();
+
+        WARN_ON(!mutex_is_locked(&nfsd_mutex));
         if (nfsd_serv) {
                 svc_get(nfsd_serv);
-                unlock_kernel();
                 return 0;
         }
         if (nfsd_max_blksize == 0) {
@@ -217,13 +228,11 @@ int nfsd_create_serv(void)
         }
 
         atomic_set(&nfsd_busy, 0);
-        nfsd_serv = svc_create_pooled(&nfsd_program,
-                                      nfsd_max_blksize,
-                                      nfsd_last_thread,
-                                      nfsd, SIG_NOCLEAN, THIS_MODULE);
+        nfsd_serv = svc_create_pooled(&nfsd_program, nfsd_max_blksize,
+                                      nfsd_last_thread, nfsd, THIS_MODULE);
         if (nfsd_serv == NULL)
                 err = -ENOMEM;
-        unlock_kernel();
+
         do_gettimeofday(&nfssvc_boot);          /* record boot time */
         return err;
 }
@@ -282,6 +291,8 @@ int nfsd_set_nrthreads(int n, int *nthreads)
         int tot = 0;
         int err = 0;
 
+        WARN_ON(!mutex_is_locked(&nfsd_mutex));
+
         if (nfsd_serv == NULL || n <= 0)
                 return 0;
 
@@ -316,7 +327,6 @@ int nfsd_set_nrthreads(int n, int *nthreads)
                 nthreads[0] = 1;
 
         /* apply the new numbers */
-        lock_kernel();
         svc_get(nfsd_serv);
         for (i = 0; i < n; i++) {
                 err = svc_set_num_threads(nfsd_serv, &nfsd_serv->sv_pools[i],
@@ -325,7 +335,6 @@ int nfsd_set_nrthreads(int n, int *nthreads)
                         break;
         }
         svc_destroy(nfsd_serv);
-        unlock_kernel();
 
         return err;
 }
@@ -334,8 +343,8 @@ int
 nfsd_svc(unsigned short port, int nrservs)
 {
         int     error;
-        
-        lock_kernel();
+
+        mutex_lock(&nfsd_mutex);
         dprintk("nfsd: creating service\n");
         error = -EINVAL;
         if (nrservs <= 0)
@@ -363,7 +372,7 @@ nfsd_svc(unsigned short port, int nrservs)
  failure:
         svc_destroy(nfsd_serv);         /* Release server */
  out:
-        unlock_kernel();
+        mutex_unlock(&nfsd_mutex);
         return error;
 }
 
@@ -391,18 +400,17 @@ update_thread_usage(int busy_threads)
 /*
  * This is the NFS server kernel thread
  */
-static void
-nfsd(struct svc_rqst *rqstp)
+static int
+nfsd(void *vrqstp)
 {
+        struct svc_rqst *rqstp = (struct svc_rqst *) vrqstp;
         struct fs_struct *fsp;
-        int             err;
-        sigset_t shutdown_mask, allowed_mask;
+        int err, preverr = 0;
 
         /* Lock module and set up kernel thread */
-        lock_kernel();
-        daemonize("nfsd");
+        mutex_lock(&nfsd_mutex);
 
-        /* After daemonize() this kernel thread shares current->fs
+        /* At this point, the thread shares current->fs
          * with the init process. We need to create files with a
          * umask of 0 instead of init's umask. */
         fsp = copy_fs_struct(current->fs);
@@ -414,14 +422,17 @@ nfsd(struct svc_rqst *rqstp)
         current->fs = fsp;
         current->fs->umask = 0;
 
-        siginitsetinv(&shutdown_mask, SHUTDOWN_SIGS);
-        siginitsetinv(&allowed_mask, ALLOWED_SIGS);
+        /*
+         * thread is spawned with all signals set to SIG_IGN, re-enable
+         * the ones that will bring down the thread
+         */
+        allow_signal(SIGKILL);
+        allow_signal(SIGHUP);
+        allow_signal(SIGINT);
+        allow_signal(SIGQUIT);
 
         nfsdstats.th_cnt++;
-
-        rqstp->rq_task = current;
-
-        unlock_kernel();
+        mutex_unlock(&nfsd_mutex);
 
         /*
          * We want less throttling in balance_dirty_pages() so that nfs to
@@ -435,26 +446,30 @@ nfsd(struct svc_rqst *rqstp)
          * The main request loop
          */
         for (;;) {
-                /* Block all but the shutdown signals */
-                sigprocmask(SIG_SETMASK, &shutdown_mask, NULL);
-
                 /*
                  * Find a socket with data available and call its
                  * recvfrom routine.
                  */
                 while ((err = svc_recv(rqstp, 60*60*HZ)) == -EAGAIN)
                         ;
-                if (err < 0)
+                if (err == -EINTR)
                         break;
+                else if (err < 0) {
+                        if (err != preverr) {
+                                printk(KERN_WARNING "%s: unexpected error "
+                                        "from svc_recv (%d)\n", __func__, -err);
+                                preverr = err;
+                        }
+                        schedule_timeout_uninterruptible(HZ);
+                        continue;
+                }
+
                 update_thread_usage(atomic_read(&nfsd_busy));
                 atomic_inc(&nfsd_busy);
 
                 /* Lock the export hash tables for reading. */
                 exp_readlock();
 
-                /* Process request with signals blocked.  */
-                sigprocmask(SIG_SETMASK, &allowed_mask, NULL);
-
                 svc_process(rqstp);
 
                 /* Unlock export hash tables */
@@ -463,22 +478,10 @@ nfsd(struct svc_rqst *rqstp)
                 atomic_dec(&nfsd_busy);
         }
 
-        if (err != -EINTR) {
-                printk(KERN_WARNING "nfsd: terminating on error %d\n", -err);
-        } else {
-                unsigned int    signo;
-
-                for (signo = 1; signo <= _NSIG; signo++)
-                        if (sigismember(&current->pending.signal, signo) &&
-                            !sigismember(&current->blocked, signo))
-                                break;
-                killsig = signo;
-        }
         /* Clear signals before calling svc_exit_thread() */
         flush_signals(current);
 
-        lock_kernel();
-
+        mutex_lock(&nfsd_mutex);
         nfsdstats.th_cnt --;
 
 out:
@@ -486,8 +489,9 @@ out:
         svc_exit_thread(rqstp);
 
         /* Release module */
-        unlock_kernel();
+        mutex_unlock(&nfsd_mutex);
         module_put_and_exit(0);
+        return 0;
 }
 
 static __be32 map_new_errors(u32 vers, __be32 nfserr)