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>

3 files changed, 14 insertions, 5 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);
diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c
index 842cb8c2f65d..1b7fa73c9436 100644
--- a/fs/nfs/nfs4state.c
+++ b/fs/nfs/nfs4state.c
@@ -254,15 +254,14 @@ static void nfs4_end_drain_session(struct nfs_client *clp)
 {
         struct nfs4_session *ses = clp->cl_session;
         struct nfs4_slot_table *tbl;
-        int max_slots;
+        unsigned int i;
 
         if (ses == NULL)
                 return;
         tbl = &ses->fc_slot_table;
         if (test_and_clear_bit(NFS4_SESSION_DRAINING, &ses->session_state)) {
                 spin_lock(&tbl->slot_tbl_lock);
-                max_slots = tbl->max_slots;
-                while (max_slots--) {
+                for (i = 0; i <= tbl->max_slotid; i++) {
                         if (rpc_wake_up_first(&tbl->slot_tbl_waitq,
                                                 nfs4_set_task_privileged,
                                                 NULL) == NULL)
@@ -2043,6 +2042,7 @@ static int nfs4_recall_slot(struct nfs_client *clp)
         old = fc_tbl->slots;
         fc_tbl->slots = new;
         fc_tbl->max_slots = fc_tbl->target_highest_slotid + 1;
+        fc_tbl->max_slotid = fc_tbl->target_highest_slotid;
         clp->cl_session->fc_attrs.max_reqs = fc_tbl->max_slots;
         spin_unlock(&fc_tbl->slot_tbl_lock);
 
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 646e64bbff4c..30715508fade 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -215,6 +215,7 @@ struct nfs4_slot_table {
         spinlock_t      slot_tbl_lock;
         struct rpc_wait_queue   slot_tbl_waitq; /* allocators may wait here */
         u32             max_slots;              /* # slots in table */
+        u32             max_slotid;             /* Max allowed slotid value */
         u32             highest_used_slotid;    /* sent to server on each SEQ.
                                                  * op for dynamic resizing */
         u32             target_highest_slotid;  /* Server max_slot target */