nfsd: optimize destroy_lockowner cl_lock thrashing

Reduce the cl_lock trashing in destroy_lockowner. Unhash all of the
lockstateids on the lockowner's list. Put the reference under the lock
and see if it was the last one. If so, then add it to a private list
to be destroyed after we drop the lock.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 9b342e1..9358cbe 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -983,14 +983,23 @@ static void nfs4_free_lock_stateid(struct nfs4_stid *stid)
        nfs4_free_ol_stateid(stid);
 }
 
-static void release_lock_stateid(struct nfs4_ol_stateid *stp)
+static void unhash_lock_stateid(struct nfs4_ol_stateid *stp)
 {
        struct nfs4_openowner *oo = openowner(stp->st_openstp->st_stateowner);
 
-       spin_lock(&oo->oo_owner.so_client->cl_lock);
-       list_del(&stp->st_locks);
+       lockdep_assert_held(&oo->oo_owner.so_client->cl_lock);
+
+       list_del_init(&stp->st_locks);
        unhash_generic_stateid(stp);
        unhash_stid(&stp->st_stid);
+}
+
+static void release_lock_stateid(struct nfs4_ol_stateid *stp)
+{
+       struct nfs4_openowner *oo = openowner(stp->st_openstp->st_stateowner);
+
+       spin_lock(&oo->oo_owner.so_client->cl_lock);
+       unhash_lock_stateid(stp);
        spin_unlock(&oo->oo_owner.so_client->cl_lock);
        nfs4_put_stid(&stp->st_stid);
 }
@@ -1004,30 +1013,38 @@ static void unhash_lockowner_locked(struct nfs4_lockowner *lo)
        list_del_init(&lo->lo_owner.so_strhash);
 }
 
-static void release_lockowner_stateids(struct nfs4_lockowner *lo)
+static void release_lockowner(struct nfs4_lockowner *lo)
 {
        struct nfs4_client *clp = lo->lo_owner.so_client;
        struct nfs4_ol_stateid *stp;
+       struct list_head reaplist;
 
-       lockdep_assert_held(&clp->cl_lock);
+       INIT_LIST_HEAD(&reaplist);
 
+       spin_lock(&clp->cl_lock);
+       unhash_lockowner_locked(lo);
        while (!list_empty(&lo->lo_owner.so_stateids)) {
                stp = list_first_entry(&lo->lo_owner.so_stateids,
                                struct nfs4_ol_stateid, st_perstateowner);
-               spin_unlock(&clp->cl_lock);
-               release_lock_stateid(stp);
-               spin_lock(&clp->cl_lock);
+               unhash_lock_stateid(stp);
+               /*
+                * We now know that no new references can be added to the
+                * stateid. If ours is the last one, finish the unhashing
+                * and put it on the list to be reaped.
+                */
+               if (atomic_dec_and_test(&stp->st_stid.sc_count)) {
+                       idr_remove(&clp->cl_stateids,
+                               stp->st_stid.sc_stateid.si_opaque.so_id);
+                       list_add(&stp->st_locks, &reaplist);
+               }
        }
-}
-
-static void release_lockowner(struct nfs4_lockowner *lo)
-{
-       struct nfs4_client *clp = lo->lo_owner.so_client;
-
-       spin_lock(&clp->cl_lock);
-       unhash_lockowner_locked(lo);
-       release_lockowner_stateids(lo);
        spin_unlock(&clp->cl_lock);
+       while (!list_empty(&reaplist)) {
+               stp = list_first_entry(&reaplist, struct nfs4_ol_stateid,
+                                       st_locks);
+               list_del(&stp->st_locks);
+               stp->st_stid.sc_free(&stp->st_stid);
+       }
        nfs4_put_stateowner(&lo->lo_owner);
 }