gfs2: Switch to rhashtable_lookup_get_insert_fast

Switch from rhashtable_lookup_insert_fast + rhashtable_lookup_fast to
rhashtable_lookup_get_insert_fast, which is cleaner and avoids an extra
rhashtable lookup.

At the same time, turn the retry loop in gfs2_glock_get into an infinite
loop.  The lookup or insert will eventually succeed, usually very fast,
but there is no reason to give up trying at a fixed number of
iterations.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

1 files changed, 21 insertions, 24 deletions

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 35f3b0a1d81b..9e81219692c4 100644
--- a/fs/gfs2/glock.c
+++ b/fs/gfs2/glock.c
@@ -655,10 +655,10 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
         struct lm_lockname name = { .ln_number = number,
                                     .ln_type = glops->go_type,
                                     .ln_sbd = sdp };
-        struct gfs2_glock *gl, *tmp = NULL;
+        struct gfs2_glock *gl, *tmp;
         struct address_space *mapping;
         struct kmem_cache *cachep;
-        int ret, tries = 0;
+        int ret = 0;
 
         rcu_read_lock();
         gl = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
@@ -723,35 +723,32 @@ int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
         }
 
 again:
-        ret = rhashtable_lookup_insert_fast(&gl_hash_table, &gl->gl_node,
-                                            ht_parms);
-        if (ret == 0) {
+        rcu_read_lock();
+        tmp = rhashtable_lookup_get_insert_fast(&gl_hash_table, &gl->gl_node,
+                                                ht_parms);
+        if (!tmp) {
                 *glp = gl;
-                return 0;
+                goto out;
         }
-
-        if (ret == -EEXIST) {
-                ret = 0;
-                rcu_read_lock();
-                tmp = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
-                if (tmp == NULL || !lockref_get_not_dead(&tmp->gl_lockref)) {
-                        if (++tries < 100) {
-                                rcu_read_unlock();
-                                cond_resched();
-                                goto again;
-                        }
-                        tmp = NULL;
-                        ret = -ENOMEM;
-                }
-                rcu_read_unlock();
-        } else {
-                WARN_ON_ONCE(ret);
+        if (IS_ERR(tmp)) {
+                ret = PTR_ERR(tmp);
+                goto out_free;
+        }
+        if (lockref_get_not_dead(&tmp->gl_lockref)) {
+                *glp = tmp;
+                goto out_free;
         }
+        rcu_read_unlock();
+        cond_resched();
+        goto again;
+
+out_free:
         kfree(gl->gl_lksb.sb_lvbptr);
         kmem_cache_free(cachep, gl);
         atomic_dec(&sdp->sd_glock_disposal);
-        *glp = tmp;
 
+out:
+        rcu_read_unlock();
         return ret;
 }