NFSv4: Allow the state manager to mark an open_owner as being recovered

This patch adds a seqcount_t lock for use by the state manager to
signal that an open owner has been recovered. This mechanism will be
used by the delegation, open and byte range lock code in order to
figure out if they need to replay requests due to collisions with
lock recovery.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index e61f68d5ef21..fff97228cdec 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -518,6 +518,7 @@ nfs4_alloc_state_owner(struct nfs_server *server,
 	nfs4_init_seqid_counter(&sp->so_seqid);
 	atomic_set(&sp->so_count, 1);
 	INIT_LIST_HEAD(&sp->so_lru);
+	seqcount_init(&sp->so_reclaim_seqcount);
 	return sp;
 }
 
@@ -1390,8 +1391,9 @@ static int nfs4_reclaim_open_state(struct nfs4_state_owner *sp, const struct nfs
 	 * recovering after a network partition or a reboot from a
 	 * server that doesn't support a grace period.
 	 */
-restart:
 	spin_lock(&sp->so_lock);
+	write_seqcount_begin(&sp->so_reclaim_seqcount);
+restart:
 	list_for_each_entry(state, &sp->so_states, open_states) {
 		if (!test_and_clear_bit(ops->state_flag_bit, &state->flags))
 			continue;
@@ -1412,6 +1414,7 @@ restart:
 				}
 				spin_unlock(&state->state_lock);
 				nfs4_put_open_state(state);
+				spin_lock(&sp->so_lock);
 				goto restart;
 			}
 		}
@@ -1449,12 +1452,17 @@ restart:
 				goto out_err;
 		}
 		nfs4_put_open_state(state);
+		spin_lock(&sp->so_lock);
 		goto restart;
 	}
+	write_seqcount_end(&sp->so_reclaim_seqcount);
 	spin_unlock(&sp->so_lock);
 	return 0;
 out_err:
 	nfs4_put_open_state(state);
+	spin_lock(&sp->so_lock);
+	write_seqcount_end(&sp->so_reclaim_seqcount);
+	spin_unlock(&sp->so_lock);
 	return status;
 }