NFSv4.1: Support dynamic resizing of the session slot table

Allow the server to control the size of the session slot table
by adjusting the value of sr_target_max_slots in the reply to the
SEQUENCE operation.

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

1 files changed, 10 insertions, 2 deletions

diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index 62212231ce62..1792ece8b53c 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -492,10 +492,17 @@ static void nfs41_sequence_free_slot(struct nfs4_sequence_res *res)
 static void nfs41_set_target_slotid_locked(struct nfs4_slot_table *tbl,
                 u32 target_highest_slotid)
 {
+        unsigned int max_slotid, i;
+
         if (tbl->target_highest_slotid == target_highest_slotid)
                 return;
         tbl->target_highest_slotid = target_highest_slotid;
         tbl->generation++;
+
+        max_slotid = min(tbl->max_slots - 1, tbl->target_highest_slotid);
+        for (i = tbl->max_slotid + 1; i <= max_slotid; i++)
+                rpc_wake_up_next(&tbl->slot_tbl_waitq);
+        tbl->max_slotid = max_slotid;
 }
 
 void nfs41_set_target_slotid(struct nfs4_slot_table *tbl,
@@ -622,8 +629,8 @@ static struct nfs4_slot *nfs4_alloc_slot(struct nfs4_slot_table *tbl)
         dprintk("--> %s used_slots=%04lx highest_used=%u max_slots=%u\n",
                 __func__, tbl->used_slots[0], tbl->highest_used_slotid,
                 tbl->max_slots);
-        slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slots);
-        if (slotid >= tbl->max_slots)
+        slotid = find_first_zero_bit(tbl->used_slots, tbl->max_slotid + 1);
+        if (slotid > tbl->max_slotid)
                 goto out;
         __set_bit(slotid, tbl->used_slots);
         if (slotid > tbl->highest_used_slotid ||
@@ -5744,6 +5751,7 @@ static void nfs4_add_and_init_slots(struct nfs4_slot_table *tbl,
         tbl->highest_used_slotid = NFS4_NO_SLOT;
         tbl->target_highest_slotid = max_slots - 1;
         tbl->server_highest_slotid = max_slots - 1;
+        tbl->max_slotid = max_slots - 1;
         for (i = 0; i < tbl->max_slots; i++)
                 tbl->slots[i].seq_nr = ivalue;
         spin_unlock(&tbl->slot_tbl_lock);