[PATCH] knfsd: lockd: introduce nsm_handle

This patch introduces the nsm_handle, which is shared by all nlm_host objects
referring to the same client.

With this patch applied, all nlm_hosts from the same address will share the
same nsm_handle.  A future patch will add sharing by name.

Note: this patch changes h_name so that it is no longer guaranteed to be an IP
address of the host.  When the host represents an NFS server, h_name will be
the name passed in the mount call.  When the host represents a client, h_name
will be the name presented in the lock request received from the client.  A
h_name is only used for printing informational messages, this change should
not be significant.

Signed-off-by: Olaf Kirch <okir@suse.de>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 136 insertions, 19 deletions

diff --git a/fs/lockd/clntlock.c b/fs/lockd/clntlock.c
index 87e1d03e8267..54e63ddef043 100644
--- a/fs/lockd/clntlock.c
+++ b/fs/lockd/clntlock.c
@@ -150,7 +150,8 @@ u32 nlmclnt_grant(const struct sockaddr_in *addr, const struct nlm_lock *lock)
 static void nlmclnt_prepare_reclaim(struct nlm_host *host)
 {
         down_write(&host->h_rwsem);
-        host->h_monitored = 0;
+        if (host->h_nsmhandle)
+                host->h_nsmhandle->sm_monitored = 0;
         host->h_state++;
         host->h_nextrebind = 0;
         nlm_rebind_host(host);
diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 481ce7ee1002..0bf4afb71d25 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -34,6 +34,8 @@ static DEFINE_MUTEX(nlm_host_mutex);
 
 
 static void                     nlm_gc_hosts(void);
+static struct nsm_handle *      __nsm_find(const struct sockaddr_in *,
+                                        const char *, int, int);
 
 /*
  * Find an NLM server handle in the cache. If there is none, create it.
@@ -68,7 +70,7 @@ nlm_lookup_host(int server, const struct sockaddr_in *sin,
                                         int hostname_len)
 {
         struct nlm_host *host, **hp;
-        u32             addr;
+        struct nsm_handle *nsm = NULL;
         int             hash;
 
         dprintk("lockd: nlm_lookup_host(%u.%u.%u.%u, p=%d, v=%d, my role=%s, name=%.*s)\n",
@@ -86,7 +88,21 @@ nlm_lookup_host(int server, const struct sockaddr_in *sin,
         if (time_after_eq(jiffies, next_gc))
                 nlm_gc_hosts();
 
+        /* We may keep several nlm_host objects for a peer, because each
+         * nlm_host is identified by
+         * (address, protocol, version, server/client)
+         * We could probably simplify this a little by putting all those
+         * different NLM rpc_clients into one single nlm_host object.
+         * This would allow us to have one nlm_host per address.
+         */
         for (hp = &nlm_hosts[hash]; (host = *hp) != 0; hp = &host->h_next) {
+                if (!nlm_cmp_addr(&host->h_addr, sin))
+                        continue;
+
+                /* See if we have an NSM handle for this client */
+                if (!nsm && (nsm = host->h_nsmhandle) != 0)
+                        atomic_inc(&nsm->sm_count);
+
                 if (host->h_proto != proto)
                         continue;
                 if (host->h_version != version)
@@ -94,7 +110,7 @@ nlm_lookup_host(int server, const struct sockaddr_in *sin,
                 if (host->h_server != server)
                         continue;
 
-                if (nlm_cmp_addr(&host->h_addr, sin)) {
+                {
                         if (hp != nlm_hosts + hash) {
                                 *hp = host->h_next;
                                 host->h_next = nlm_hosts[hash];
@@ -106,16 +122,18 @@ nlm_lookup_host(int server, const struct sockaddr_in *sin,
                 }
         }
 
-        /* Ooops, no host found, create it */
-        dprintk("lockd: creating host entry\n");
+        /* Sadly, the host isn't in our hash table yet. See if
+         * we have an NSM handle for it. If not, create one.
+         */
+        if (!nsm && !(nsm = nsm_find(sin, hostname, hostname_len)))
+                goto out;
 
         host = kzalloc(sizeof(*host), GFP_KERNEL);
-        if (!host)
-                goto nohost;
-
-        addr = sin->sin_addr.s_addr;
-        sprintf(host->h_name, "%u.%u.%u.%u", NIPQUAD(addr));
-
+        if (!host) {
+                nsm_release(nsm);
+                goto out;
+        }
+        host->h_name       = nsm->sm_name;
         host->h_addr       = *sin;
         host->h_addr.sin_port = 0;      /* ouch! */
         host->h_version    = version;
@@ -129,6 +147,7 @@ nlm_lookup_host(int server, const struct sockaddr_in *sin,
         init_rwsem(&host->h_rwsem);
         host->h_state      = 0;                 /* pseudo NSM state */
         host->h_nsmstate   = 0;                 /* real NSM state */
+        host->h_nsmhandle  = nsm;
         host->h_server     = server;
         host->h_next       = nlm_hosts[hash];
         nlm_hosts[hash]    = host;
@@ -140,7 +159,7 @@ nlm_lookup_host(int server, const struct sockaddr_in *sin,
         if (++nrhosts > NLM_HOST_MAX)
                 next_gc = 0;
 
-nohost:
+out:
         mutex_unlock(&nlm_host_mutex);
         return host;
 }
@@ -393,3 +412,83 @@ nlm_gc_hosts(void)
         next_gc = jiffies + NLM_HOST_COLLECT;
 }
 
+
+/*
+ * Manage NSM handles
+ */
+static LIST_HEAD(nsm_handles);
+static DECLARE_MUTEX(nsm_sema);
+
+static struct nsm_handle *
+__nsm_find(const struct sockaddr_in *sin,
+                const char *hostname, int hostname_len,
+                int create)
+{
+        struct nsm_handle *nsm = NULL;
+        struct list_head *pos;
+
+        if (!sin)
+                return NULL;
+
+        if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
+                if (printk_ratelimit()) {
+                        printk(KERN_WARNING "Invalid hostname \"%.*s\" "
+                                            "in NFS lock request\n",
+                                hostname_len, hostname);
+                }
+                return NULL;
+        }
+
+        down(&nsm_sema);
+        list_for_each(pos, &nsm_handles) {
+                nsm = list_entry(pos, struct nsm_handle, sm_link);
+
+                if (!nlm_cmp_addr(&nsm->sm_addr, sin))
+                        continue;
+                atomic_inc(&nsm->sm_count);
+                goto out;
+        }
+
+        if (!create) {
+                nsm = NULL;
+                goto out;
+        }
+
+        nsm = kzalloc(sizeof(*nsm) + hostname_len + 1, GFP_KERNEL);
+        if (nsm != NULL) {
+                nsm->sm_addr = *sin;
+                nsm->sm_name = (char *) (nsm + 1);
+                memcpy(nsm->sm_name, hostname, hostname_len);
+                nsm->sm_name[hostname_len] = '\0';
+                atomic_set(&nsm->sm_count, 1);
+
+                list_add(&nsm->sm_link, &nsm_handles);
+        }
+
+out:    up(&nsm_sema);
+        return nsm;
+}
+
+struct nsm_handle *
+nsm_find(const struct sockaddr_in *sin, const char *hostname, int hostname_len)
+{
+        return __nsm_find(sin, hostname, hostname_len, 1);
+}
+
+/*
+ * Release an NSM handle
+ */
+void
+nsm_release(struct nsm_handle *nsm)
+{
+        if (!nsm)
+                return;
+        if (atomic_dec_and_test(&nsm->sm_count)) {
+                down(&nsm_sema);
+                if (atomic_read(&nsm->sm_count) == 0) {
+                        list_del(&nsm->sm_link);
+                        kfree(nsm);
+                }
+                up(&nsm_sema);
+        }
+}
diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index e02a1a4dfced..e27981403fbe 100644
--- a/fs/lockd/mon.c
+++ b/fs/lockd/mon.c
@@ -70,11 +70,14 @@ nsm_mon_unmon(struct nlm_host *host, u32 proc, struct nsm_res *res)
 int
 nsm_monitor(struct nlm_host *host)
 {
+        struct nsm_handle *nsm = host->h_nsmhandle;
         struct nsm_res  res;
         int             status;
 
         dprintk("lockd: nsm_monitor(%s)\n", host->h_name);
-        if (host->h_monitored)
+        BUG_ON(nsm == NULL);
+
+        if (nsm->sm_monitored)
                 return 0;
 
         status = nsm_mon_unmon(host, SM_MON, &res);
@@ -82,7 +85,7 @@ nsm_monitor(struct nlm_host *host)
         if (status < 0 || res.status != 0)
                 printk(KERN_NOTICE "lockd: cannot monitor %s\n", host->h_name);
         else
-                host->h_monitored = 1;
+                nsm->sm_monitored = 1;
         return status;
 }
 
@@ -92,19 +95,22 @@ nsm_monitor(struct nlm_host *host)
 int
 nsm_unmonitor(struct nlm_host *host)
 {
+        struct nsm_handle *nsm = host->h_nsmhandle;
         struct nsm_res  res;
         int             status = 0;
 
         dprintk("lockd: nsm_unmonitor(%s)\n", host->h_name);
-        if (!host->h_monitored)
+        if (nsm == NULL)
                 return 0;
-        host->h_monitored = 0;
+        host->h_nsmhandle = NULL;
 
         if (!host->h_killed) {
                 status = nsm_mon_unmon(host, SM_UNMON, &res);
                 if (status < 0)
                         printk(KERN_NOTICE "lockd: cannot unmonitor %s\n", host->h_name);
+                nsm->sm_monitored = 0;
         }
+        nsm_release(nsm);
         return status;
 }
 
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index 0f9b236bca7f..ab2ffc8a0b44 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -40,14 +40,13 @@ struct nlm_host {
         struct nlm_host *       h_next;         /* linked list (hash table) */
         struct sockaddr_in      h_addr;         /* peer address */
         struct rpc_clnt *       h_rpcclnt;      /* RPC client to talk to peer */
-        char                    h_name[20];     /* remote hostname */
+        char *                  h_name;         /* remote hostname */
         u32                     h_version;      /* interface version */
         unsigned short          h_proto;        /* transport proto */
         unsigned short          h_reclaiming : 1,
                                 h_server     : 1, /* server side, not client side */
                                 h_inuse      : 1,
-                                h_killed     : 1,
-                                h_monitored  : 1;
+                                h_killed     : 1;
         wait_queue_head_t       h_gracewait;    /* wait while reclaiming */
         struct rw_semaphore     h_rwsem;        /* Reboot recovery lock */
         u32                     h_state;        /* pseudo-state counter */
@@ -61,6 +60,16 @@ struct nlm_host {
         spinlock_t              h_lock;
         struct list_head        h_granted;      /* Locks in GRANTED state */
         struct list_head        h_reclaim;      /* Locks in RECLAIM state */
+        struct nsm_handle *     h_nsmhandle;    /* NSM status handle */
+};
+
+struct nsm_handle {
+        struct list_head        sm_link;
+        atomic_t                sm_count;
+        char *                  sm_name;
+        struct sockaddr_in      sm_addr;
+        unsigned int            sm_monitored : 1,
+                                sm_sticky : 1;  /* don't unmonitor */
 };
 
 /*
@@ -171,6 +180,8 @@ void		  nlm_release_host(struct nlm_host *);
 void              nlm_shutdown_hosts(void);
 extern struct nlm_host *nlm_find_client(void);
 extern void       nlm_host_rebooted(const struct sockaddr_in *, const struct nlm_reboot *);
+struct nsm_handle *nsm_find(const struct sockaddr_in *, const char *, int);
+void              nsm_release(struct nsm_handle *);
 
 
 /*