NFSv4.1: Be conservative about the client highest slotid

If the server sends us a target that looks like an outlier, but
is lower than the existing target, then respect it anyway.
However defer actually updating the generation counter until
we get a target that doesn't look like an outlier.

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

diff --git a/fs/nfs/nfs4session.c b/fs/nfs/nfs4session.c
index ed5aa9f..1e6c87c 100644 (file)
--- a/fs/nfs/nfs4session.c
+++ b/fs/nfs/nfs4session.c
@@ -273,20 +273,28 @@ void nfs41_wake_slot_table(struct nfs4_slot_table *tbl)
        }
 }
 
+static void nfs41_set_max_slotid_locked(struct nfs4_slot_table *tbl,
+               u32 target_highest_slotid)
+{
+       u32 max_slotid;
+
+       max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, target_highest_slotid);
+       if (max_slotid > tbl->server_highest_slotid)
+               max_slotid = tbl->server_highest_slotid;
+       if (max_slotid > tbl->target_highest_slotid)
+               max_slotid = tbl->target_highest_slotid;
+       tbl->max_slotid = max_slotid;
+       nfs41_wake_slot_table(tbl);
+}
+
 /* Update the client's idea of target_highest_slotid */
 static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
                u32 target_highest_slotid)
 {
-       unsigned int max_slotid;
-
        if (tbl->target_highest_slotid == target_highest_slotid)
                return;
        tbl->target_highest_slotid = target_highest_slotid;
        tbl->generation++;
-
-       max_slotid = min(NFS4_MAX_SLOT_TABLE - 1, tbl->target_highest_slotid);
-       tbl->max_slotid = max_slotid;
-       nfs41_wake_slot_table(tbl);
 }
 
 void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
@@ -296,6 +304,7 @@ void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
        nfs41_set_target_slotid_locked(tbl, target_highest_slotid);
        tbl->d_target_highest_slotid = 0;
        tbl->d2_target_highest_slotid = 0;
+       nfs41_set_max_slotid_locked(tbl, target_highest_slotid);
        spin_unlock(&tbl->slot_tbl_lock);
 }
 
@@ -370,6 +379,7 @@ void nfs41_update_target_slotid(struct nfs4_slot_table *tbl,
                nfs41_set_target_slotid_locked(tbl, res->sr_target_highest_slotid);
        if (tbl->generation == slot->generation)
                nfs41_set_server_slotid_locked(tbl, res->sr_highest_slotid);
+       nfs41_set_max_slotid_locked(tbl, res->sr_target_highest_slotid);
        spin_unlock(&tbl->slot_tbl_lock);
 }