LU-2948 osc: keep trying to shrink more LRU slots

It used to try once. It can enter into a livelock state as we can
see it in this ticket.

Signed-off-by: Jinshan Xiong <jinshan.xiong@intel.com>
Change-Id: If603686d1d9fa7cf6513143fcc6ef962cfea9863
Reviewed-on: http://review.whamcloud.com/5760
Tested-by: Hudson
Reviewed-by: Prakash Surya <surya1@llnl.gov>
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Faccini Bruno <bruno.faccini@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/osc/osc_page.c b/lustre/osc/osc_page.c
index 5c6102a..cafcaac 100644 (file)
--- a/lustre/osc/osc_page.c
+++ b/lustre/osc/osc_page.c
@@ -717,6 +717,7 @@ int osc_lru_shrink(struct client_obd *cli, int target)
 
                        clobj = tmp;
                        io->ci_obj = clobj;
+                       io->ci_ignore_layout = 1;
                        rc = cl_io_init(env, io, CIT_MISC, clobj);
 
                        client_obd_list_lock(&cli->cl_lru_list_lock);
@@ -778,8 +779,10 @@ static void osc_lru_add(struct client_obd *cli, struct osc_page *opg)
        }
        client_obd_list_unlock(&cli->cl_lru_list_lock);
 
-       if (wakeup)
+       if (wakeup) {
+               osc_lru_shrink(cli, osc_cache_too_much(cli));
                cfs_waitq_broadcast(&osc_lru_waitq);
+       }
 }
 
 /* delete page from LRUlist. The page can be deleted from LRUlist for two
@@ -815,18 +818,22 @@ static void osc_lru_del(struct client_obd *cli, struct osc_page *opg, bool del)
        }
 }
 
+static inline int max_to_shrink(struct client_obd *cli)
+{
+       return min(cfs_atomic_read(&cli->cl_lru_in_list) >> 1, lru_shrink_max);
+}
+
 static int osc_lru_reclaim(struct client_obd *cli)
 {
        struct cl_client_cache *cache = cli->cl_cache;
-       struct client_obd *victim;
-       struct client_obd *tmp;
+       int max_scans;
        int rc;
 
        LASSERT(cache != NULL);
        LASSERT(!cfs_list_empty(&cache->ccc_lru));
 
        rc = osc_lru_shrink(cli, lru_shrink_min);
-       if (rc > 0) {
+       if (rc != 0) {
                CDEBUG(D_CACHE, "%s: Free %d pages from own LRU: %p.\n",
                        cli->cl_import->imp_obd->obd_name, rc, cli);
                return rc;
@@ -842,33 +849,31 @@ static int osc_lru_reclaim(struct client_obd *cli)
        spin_lock(&cache->ccc_lru_lock);
        cache->ccc_lru_shrinkers++;
        cfs_list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
-       cfs_list_for_each_entry_safe(victim, tmp, &cache->ccc_lru, cl_lru_osc) {
-               if (victim == cli)
-                       break;
+
+       max_scans = cfs_atomic_read(&cache->ccc_users);
+       while (--max_scans > 0 && !cfs_list_empty(&cache->ccc_lru)) {
+               cli = cfs_list_entry(cache->ccc_lru.next, struct client_obd,
+                                       cl_lru_osc);
 
                CDEBUG(D_CACHE, "%s: cli %p LRU pages: %d, busy: %d.\n",
-                       victim->cl_import->imp_obd->obd_name, victim,
-                       cfs_atomic_read(&victim->cl_lru_in_list),
-                       cfs_atomic_read(&victim->cl_lru_busy));
+                       cli->cl_import->imp_obd->obd_name, cli,
+                       cfs_atomic_read(&cli->cl_lru_in_list),
+                       cfs_atomic_read(&cli->cl_lru_busy));
 
-               cfs_list_move_tail(&victim->cl_lru_osc, &cache->ccc_lru);
-               if (cfs_atomic_read(&victim->cl_lru_in_list) > 0)
-                       break;
+               cfs_list_move_tail(&cli->cl_lru_osc, &cache->ccc_lru);
+               if (cfs_atomic_read(&cli->cl_lru_in_list) > 0) {
+                       spin_unlock(&cache->ccc_lru_lock);
+
+                       rc = osc_lru_shrink(cli, max_to_shrink(cli));
+                       spin_lock(&cache->ccc_lru_lock);
+                       if (rc != 0)
+                               break;
+               }
        }
        spin_unlock(&cache->ccc_lru_lock);
-       if (victim == cli) {
-               CDEBUG(D_CACHE, "%s: can't get any free LRU slots.\n",
-                       cli->cl_import->imp_obd->obd_name);
-               return 0;
-       }
-
-       rc = osc_lru_shrink(victim,
-                           min(cfs_atomic_read(&victim->cl_lru_in_list) >> 1,
-                               lru_shrink_max));
-
-       CDEBUG(D_CACHE, "%s: Free %d pages from other cli: %p.\n",
-               cli->cl_import->imp_obd->obd_name, rc, victim);
 
+       CDEBUG(D_CACHE, "%s: cli %p freed %d pages.\n",
+               cli->cl_import->imp_obd->obd_name, cli, rc);
        return rc;
 }