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>

diff --git a/fs/gfs2/glock.c b/fs/gfs2/glock.c
index 35f3b0a1d81b30585a3d2da3759eab7fb2f0fdb6..9e81219692c494a39b65cc7ff5f3a32af88d23a4 100644 (file)
--- 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;
 }