NFSv4.1: Add a module parameter to set the number of session slots

Add the module parameter 'max_session_slots' to set the initial number
of slots that the NFSv4.1 client will attempt to negotiate with the
server.

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

3 files changed, 18 insertions, 3 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 033d4e69b43b..1d369c6286e1 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1657,6 +1657,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         of returning the full 64-bit number.
                         The default is to return 64-bit inode numbers.
 
+        nfs.max_session_slots=
+                        [NFSv4.1] Sets the maximum number of session slots
+                        the client will attempt to negotiate with the server.
+                        This limits the number of simultaneous RPC requests
+                        that the client can send to the NFSv4.1 server.
+                        Note that there is little point in setting this
+                        value higher than the max_tcp_slot_table_limit.
+
         nfs.nfs4_disable_idmapping=
                         [NFSv4] When set to the default of '1', this option
                         ensures that both the RPC level authentication
diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c
index f3f56f4a3b72..0b3316541734 100644
--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -72,6 +72,8 @@
 
 #define NFS4_MAX_LOOP_ON_RECOVER (10)
 
+static unsigned short max_session_slots = NFS4_DEF_SLOT_TABLE_SIZE;
+
 struct nfs4_opendata;
 static int _nfs4_proc_open(struct nfs4_opendata *data);
 static int _nfs4_recover_proc_open(struct nfs4_opendata *data);
@@ -5245,7 +5247,7 @@ static void nfs4_init_channel_attrs(struct nfs41_create_session_args *args)
         args->fc_attrs.max_rqst_sz = mxrqst_sz;
         args->fc_attrs.max_resp_sz = mxresp_sz;
         args->fc_attrs.max_ops = NFS4_MAX_OPS;
-        args->fc_attrs.max_reqs = session->clp->cl_rpcclient->cl_xprt->max_reqs;
+        args->fc_attrs.max_reqs = max_session_slots;
 
         dprintk("%s: Fore Channel : max_rqst_sz=%u max_resp_sz=%u "
                 "max_ops=%u max_reqs=%u\n",
@@ -6390,6 +6392,10 @@ const struct xattr_handler *nfs4_xattr_handlers[] = {
         NULL
 };
 
+module_param(max_session_slots, ushort, 0644);
+MODULE_PARM_DESC(max_session_slots, "Maximum number of outstanding NFSv4.1 "
+                "requests the client will negotiate");
+
 /*
  * Local variables:
  *  c-basic-offset: 8
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index 2ae57f2f645b..3bf47666646e 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -190,13 +190,14 @@ struct nfs_server {
 
 
 /* maximum number of slots to use */
-#define NFS4_MAX_SLOT_TABLE (128U)
+#define NFS4_DEF_SLOT_TABLE_SIZE (16U)
+#define NFS4_MAX_SLOT_TABLE (256U)
 #define NFS4_NO_SLOT ((u32)-1)
 
 #if defined(CONFIG_NFS_V4)
 
 /* Sessions */
-#define SLOT_TABLE_SZ (NFS4_MAX_SLOT_TABLE/(8*sizeof(long)))
+#define SLOT_TABLE_SZ DIV_ROUND_UP(NFS4_MAX_SLOT_TABLE, 8*sizeof(long))
 struct nfs4_slot_table {
         struct nfs4_slot *slots;                /* seqid per slot */
         unsigned long   used_slots[SLOT_TABLE_SZ]; /* used/unused bitmap */