NFSv4.1: Ensure that the client tracks the server target_highest_slotid

Dynamic slot allocation in NFSv4.1 depends on the client being able to
track the server's target value for the highest slotid in the
slot table.  See the reference in Section 2.10.6.1 of RFC5661.

To avoid ordering problems in the case where 2 SEQUENCE replies contain
conflicting updates to this target value, we also introduce a generation
counter, to track whether or not an RPC containing a SEQUENCE operation
was launched before or after the last update.

Also rename the nfs4_slot_table target_max_slots field to
'target_highest_slotid' to avoid confusion with a slot
table size or number of slots.

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

2 files changed, 5 insertions, 2 deletions

diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index b0412873d29c..57d406997def 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -217,8 +217,9 @@ struct nfs4_slot_table {
         u32             max_slots;              /* # slots in table */
         u32             highest_used_slotid;    /* sent to server on each SEQ.
                                                  * op for dynamic resizing */
-        u32             target_max_slots;       /* Set by CB_RECALL_SLOT as
-                                                 * the new max_slots */
+        u32             target_highest_slotid;  /* Server max_slot target */
+        unsigned long   generation;             /* Generation counter for
+                                                   target_highest_slotid */
         struct completion complete;
 };
 
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index deb31bbbb857..08c47db7417f 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -188,6 +188,7 @@ struct nfs4_channel_attrs {
 /* nfs41 sessions slot seqid */
 struct nfs4_slot {
         struct nfs4_slot_table  *table;
+        unsigned long           generation;
         unsigned long           renewal_time;
         u32                     slot_nr;
         u32                     seq_nr;
@@ -202,6 +203,7 @@ struct nfs4_sequence_res {
         struct nfs4_slot        *sr_slot;       /* slot used to send request */
         int                     sr_status;      /* sequence operation status */
         u32                     sr_status_flags;
+        u32                     sr_target_highest_slotid;
 };
 
 struct nfs4_get_lease_time_args {