staging/lustre/ldlm: convert to shrinkers to count/scan API

convert ldlm shrinker to new count/scan API.

Signed-off-by: Peng Tao <tao.peng@emc.com>
Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 79 insertions, 69 deletions

diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
index 454027d68d54..0025ee6356da 100644
--- a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
+++ b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
@@ -521,7 +521,7 @@ static int ldlm_cli_pool_shrink(struct ldlm_pool *pl,
                                 int nr, unsigned int gfp_mask)
 {
         struct ldlm_namespace *ns;
-        int canceled = 0, unused;
+        int unused;
 
         ns = ldlm_pl2ns(pl);
 
@@ -540,14 +540,10 @@ static int ldlm_cli_pool_shrink(struct ldlm_pool *pl,
         unused = ns->ns_nr_unused;
         spin_unlock(&ns->ns_lock);
 
-        if (nr) {
-                canceled = ldlm_cancel_lru(ns, nr, LCF_ASYNC,
-                                           LDLM_CANCEL_SHRINK);
-        }
-        /*
-         * Return the number of potentially reclaimable locks.
-         */
-        return ((unused - canceled) / 100) * sysctl_vfs_cache_pressure;
+        if (nr == 0)
+                return (unused / 100) * sysctl_vfs_cache_pressure;
+        else
+                return ldlm_cancel_lru(ns, nr, LCF_ASYNC, LDLM_CANCEL_SHRINK);
 }
 
 struct ldlm_pool_ops ldlm_srv_pool_ops = {
@@ -601,9 +597,10 @@ int ldlm_pool_recalc(struct ldlm_pool *pl)
         return recalc_interval_sec;
 }
 
-/**
+/*
  * Pool shrink wrapper. Will call either client or server pool recalc callback
- * depending what pool \a pl is used.
+ * depending what pool pl is used. When nr == 0, just return the number of
+ * freeable locks. Otherwise, return the number of canceled locks.
  */
 int ldlm_pool_shrink(struct ldlm_pool *pl, int nr,
                      unsigned int gfp_mask)
@@ -1017,29 +1014,24 @@ static int ldlm_pool_granted(struct ldlm_pool *pl)
 }
 
 static struct ptlrpc_thread *ldlm_pools_thread;
-static struct shrinker *ldlm_pools_srv_shrinker;
-static struct shrinker *ldlm_pools_cli_shrinker;
 static struct completion ldlm_pools_comp;
 
 /*
- * Cancel \a nr locks from all namespaces (if possible). Returns number of
- * cached locks after shrink is finished. All namespaces are asked to
- * cancel approximately equal amount of locks to keep balancing.
+ * count locks from all namespaces (if possible). Returns number of
+ * cached locks.
  */
-static int ldlm_pools_shrink(ldlm_side_t client, int nr,
-                             unsigned int gfp_mask)
+static unsigned long ldlm_pools_count(ldlm_side_t client, unsigned int gfp_mask)
 {
-        int total = 0, cached = 0, nr_ns;
+        int total = 0, nr_ns;
         struct ldlm_namespace *ns;
         struct ldlm_namespace *ns_old = NULL; /* loop detection */
         void *cookie;
 
-        if (client == LDLM_NAMESPACE_CLIENT && nr != 0 &&
-            !(gfp_mask & __GFP_FS))
-                return -1;
+        if (client == LDLM_NAMESPACE_CLIENT && !(gfp_mask & __GFP_FS))
+                return 0;
 
-        CDEBUG(D_DLMTRACE, "Request to shrink %d %s locks from all pools\n",
-               nr, client == LDLM_NAMESPACE_CLIENT ? "client" : "server");
+        CDEBUG(D_DLMTRACE, "Request to count %s locks from all pools\n",
+               client == LDLM_NAMESPACE_CLIENT ? "client" : "server");
 
         cookie = cl_env_reenter();
 
@@ -1047,8 +1039,7 @@ static int ldlm_pools_shrink(ldlm_side_t client, int nr,
          * Find out how many resources we may release.
          */
         for (nr_ns = ldlm_namespace_nr_read(client);
-             nr_ns > 0; nr_ns--)
-        {
+             nr_ns > 0; nr_ns--) {
                 mutex_lock(ldlm_namespace_lock(client));
                 if (list_empty(ldlm_namespace_list(client))) {
                         mutex_unlock(ldlm_namespace_lock(client));
@@ -1078,17 +1069,27 @@ static int ldlm_pools_shrink(ldlm_side_t client, int nr,
                 ldlm_namespace_put(ns);
         }
 
-        if (nr == 0 || total == 0) {
-                cl_env_reexit(cookie);
-                return total;
-        }
+        cl_env_reexit(cookie);
+        return total;
+}
+
+static unsigned long ldlm_pools_scan(ldlm_side_t client, int nr, unsigned int gfp_mask)
+{
+        unsigned long freed = 0;
+        int tmp, nr_ns;
+        struct ldlm_namespace *ns;
+        void *cookie;
+
+        if (client == LDLM_NAMESPACE_CLIENT && !(gfp_mask & __GFP_FS))
+                return -1;
+
+        cookie = cl_env_reenter();
 
         /*
-         * Shrink at least ldlm_namespace_nr(client) namespaces.
+         * Shrink at least ldlm_namespace_nr_read(client) namespaces.
          */
-        for (nr_ns = ldlm_namespace_nr_read(client) - nr_ns;
-             nr_ns > 0; nr_ns--)
-        {
+        for (tmp = nr_ns = ldlm_namespace_nr_read(client);
+             tmp > 0; tmp--) {
                 int cancel, nr_locks;
 
                 /*
@@ -1097,12 +1098,6 @@ static int ldlm_pools_shrink(ldlm_side_t client, int nr,
                 mutex_lock(ldlm_namespace_lock(client));
                 if (list_empty(ldlm_namespace_list(client))) {
                         mutex_unlock(ldlm_namespace_lock(client));
-                        /*
-                         * If list is empty, we can't return any @cached > 0,
-                         * that probably would cause needless shrinker
-                         * call.
-                         */
-                        cached = 0;
                         break;
                 }
                 ns = ldlm_namespace_first_locked(client);
@@ -1111,29 +1106,42 @@ static int ldlm_pools_shrink(ldlm_side_t client, int nr,
                 mutex_unlock(ldlm_namespace_lock(client));
 
                 nr_locks = ldlm_pool_granted(&ns->ns_pool);
-                cancel = 1 + nr_locks * nr / total;
-                ldlm_pool_shrink(&ns->ns_pool, cancel, gfp_mask);
-                cached += ldlm_pool_granted(&ns->ns_pool);
+                /*
+                 * We use to shrink propotionally but with new shrinker API,
+                 * we lost the total number of freeable locks.
+                 */
+                cancel = 1 + min_t(int, nr_locks, nr / nr_ns);
+                freed += ldlm_pool_shrink(&ns->ns_pool, cancel, gfp_mask);
                 ldlm_namespace_put(ns);
         }
         cl_env_reexit(cookie);
-        /* we only decrease the SLV in server pools shrinker, return -1 to
-         * kernel to avoid needless loop. LU-1128 */
-        return (client == LDLM_NAMESPACE_SERVER) ? -1 : cached;
+        /*
+         * we only decrease the SLV in server pools shrinker, return
+         * SHRINK_STOP to kernel to avoid needless loop. LU-1128
+         */
+        return (client == LDLM_NAMESPACE_SERVER) ? SHRINK_STOP : freed;
+}
+
+static unsigned long ldlm_pools_srv_count(struct shrinker *s, struct shrink_control *sc)
+{
+        return ldlm_pools_count(LDLM_NAMESPACE_SERVER, sc->gfp_mask);
 }
 
-static int ldlm_pools_srv_shrink(SHRINKER_ARGS(sc, nr_to_scan, gfp_mask))
+static unsigned long ldlm_pools_srv_scan(struct shrinker *s, struct shrink_control *sc)
 {
-        return ldlm_pools_shrink(LDLM_NAMESPACE_SERVER,
-                                 shrink_param(sc, nr_to_scan),
-                                 shrink_param(sc, gfp_mask));
+        return ldlm_pools_scan(LDLM_NAMESPACE_SERVER, sc->nr_to_scan,
+                               sc->gfp_mask);
 }
 
-static int ldlm_pools_cli_shrink(SHRINKER_ARGS(sc, nr_to_scan, gfp_mask))
+static unsigned long ldlm_pools_cli_count(struct shrinker *s, struct shrink_control *sc)
 {
-        return ldlm_pools_shrink(LDLM_NAMESPACE_CLIENT,
-                                 shrink_param(sc, nr_to_scan),
-                                 shrink_param(sc, gfp_mask));
+        return ldlm_pools_count(LDLM_NAMESPACE_CLIENT, sc->gfp_mask);
+}
+
+static unsigned long ldlm_pools_cli_scan(struct shrinker *s, struct shrink_control *sc)
+{
+        return ldlm_pools_scan(LDLM_NAMESPACE_CLIENT, sc->nr_to_scan,
+                               sc->gfp_mask);
 }
 
 int ldlm_pools_recalc(ldlm_side_t client)
@@ -1216,7 +1224,7 @@ int ldlm_pools_recalc(ldlm_side_t client)
         }
 
         /*
-         * Recalc at least ldlm_namespace_nr(client) namespaces.
+         * Recalc at least ldlm_namespace_nr_read(client) namespaces.
          */
         for (nr = ldlm_namespace_nr_read(client); nr > 0; nr--) {
                 int     skip;
@@ -1383,18 +1391,26 @@ static void ldlm_pools_thread_stop(void)
         ldlm_pools_thread = NULL;
 }
 
+static struct shrinker ldlm_pools_srv_shrinker = {
+        .count_objects  = ldlm_pools_srv_count,
+        .scan_objects   = ldlm_pools_srv_scan,
+        .seeks          = DEFAULT_SEEKS,
+};
+
+static struct shrinker ldlm_pools_cli_shrinker = {
+        .count_objects  = ldlm_pools_cli_count,
+        .scan_objects   = ldlm_pools_cli_scan,
+        .seeks          = DEFAULT_SEEKS,
+};
+
 int ldlm_pools_init(void)
 {
         int rc;
 
         rc = ldlm_pools_thread_start();
         if (rc == 0) {
-                ldlm_pools_srv_shrinker =
-                        set_shrinker(DEFAULT_SEEKS,
-                                         ldlm_pools_srv_shrink);
-                ldlm_pools_cli_shrinker =
-                        set_shrinker(DEFAULT_SEEKS,
-                                         ldlm_pools_cli_shrink);
+                register_shrinker(&ldlm_pools_srv_shrinker);
+                register_shrinker(&ldlm_pools_cli_shrinker);
         }
         return rc;
 }
@@ -1402,14 +1418,8 @@ EXPORT_SYMBOL(ldlm_pools_init);
 
 void ldlm_pools_fini(void)
 {
-        if (ldlm_pools_srv_shrinker != NULL) {
-                remove_shrinker(ldlm_pools_srv_shrinker);
-                ldlm_pools_srv_shrinker = NULL;
-        }
-        if (ldlm_pools_cli_shrinker != NULL) {
-                remove_shrinker(ldlm_pools_cli_shrinker);
-                ldlm_pools_cli_shrinker = NULL;
-        }
+        unregister_shrinker(&ldlm_pools_srv_shrinker);
+        unregister_shrinker(&ldlm_pools_cli_shrinker);
         ldlm_pools_thread_stop();
 }
 EXPORT_SYMBOL(ldlm_pools_fini);