nfsd41: create_session operation

Implement the create_session operation confoming to
http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-26

Look up the client id (generated by the server on exchange_id,
given by the client on create_session).
If neither a confirmed or unconfirmed client is found
then the client id is stale
If a confirmed cilent is found (i.e. we already received
create_session for it) then compare the sequence id
to determine if it's a replay or possibly a mis-ordered rpc.
If the seqid is in order, update the confirmed client seqid
and procedd with updating the session parameters.

If an unconfirmed client_id is found then verify the creds
and seqid.  If both match move the client id to confirmed state
and proceed with processing the create_session.

Currently, we do not support persistent sessions, and RDMA.

alloc_init_session generates a new sessionid and creates
a session structure.

NFSD_PAGES_PER_SLOT is used for the max response cached calculation, and for
the counting of DRC pages using the hard limits set in struct srv_serv.

A note on NFSD_PAGES_PER_SLOT:

Other patches in this series allow for NFSD_PAGES_PER_SLOT + 1 pages to be
cached in a DRC slot when the response size is less than NFSD_PAGES_PER_SLOT *
PAGE_SIZE but xdr_buf pages are used. e.g. a READDIR operation will encode a
small amount of data in the xdr_buf head, and then the READDIR in the xdr_buf
pages.  So, the hard limit calculation use of pages by a session is
underestimated by the number of cached operations using the xdr_buf pages.

Yet another patch caches no pages for the solo sequence operation, or any
compound where cache_this is False.  So the hard limit calculation use of
pages by a session is overestimated by the number of these operations in the
cache.

TODO: improve resource pre-allocation and negotiate session
parameters accordingly.  Respect and possibly adjust
backchannel attributes.

Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Dean Hildebrand <dhildeb@us.ibm.com>
[nfsd41: remove headerpadsz from channel attributes]
Our client and server only support a headerpadsz of 0.
[nfsd41: use DRC limits in fore channel init]
[nfsd41: do not change CREATE_SESSION back channel attrs]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[use sessionid_lock spin lock]
[nfsd41: use bool inuse for slot state]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[nfsd41 remove sl_session from alloc_init_session]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[simplify nfsd4_encode_create_session error handling]
[nfsd41: fix comment style in init_forechannel_attrs]
[nfsd41: allocate struct nfsd4_session and slot table in one piece]
[nfsd41: no need to INIT_LIST_HEAD in alloc_init_session just prior to list_add]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

2 files changed, 26 insertions, 2 deletions

diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
index f1edb1d98523..692edf4c2e7c 100644
--- a/include/linux/nfsd/state.h
+++ b/include/linux/nfsd/state.h
@@ -99,8 +99,12 @@ struct nfs4_callback {
         struct rpc_clnt *       cb_client;
 };
 
+/* Maximum number of slots per session. 128 is useful for long haul TCP */
+#define NFSD_MAX_SLOTS_PER_SESSION      128
 /* Maximum number of pages per slot cache entry */
 #define NFSD_PAGES_PER_SLOT     1
+/* Maximum number of operations per session compound */
+#define NFSD_MAX_OPS_PER_COMPOUND       16
 
 struct nfsd4_cache_entry {
         __be32          ce_status;
@@ -129,7 +133,7 @@ struct nfsd4_session {
         u32                     se_fmaxresp_cached;
         u32                     se_fmaxops;
         u32                     se_fnumslots;
-        struct nfsd4_slot       *se_slots;      /* forward channel slots */
+        struct nfsd4_slot       se_slots[];     /* forward channel slots */
 };
 
 static inline void
@@ -188,6 +192,7 @@ struct nfs4_client {
         struct list_head        cl_sessions;
         u32                     cl_seqid;       /* seqid for create_session */
         u32                     cl_exchange_flags;
+        struct nfs4_sessionid   cl_sessionid;
 };
 
 /* struct nfs4_client_reset
diff --git a/include/linux/nfsd/xdr4.h b/include/linux/nfsd/xdr4.h
index 69cb467cb720..9468829adb70 100644
--- a/include/linux/nfsd/xdr4.h
+++ b/include/linux/nfsd/xdr4.h
@@ -359,8 +359,27 @@ struct nfsd4_exchange_id {
         int             spa_how;
 };
 
+struct nfsd4_channel_attrs {
+        u32             headerpadsz;
+        u32             maxreq_sz;
+        u32             maxresp_sz;
+        u32             maxresp_cached;
+        u32             maxops;
+        u32             maxreqs;
+        u32             nr_rdma_attrs;
+        u32             rdma_attrs;
+};
+
 struct nfsd4_create_session {
-        int     foo;    /* stub */
+        clientid_t              clientid;
+        struct nfs4_sessionid   sessionid;
+        u32                     seqid;
+        u32                     flags;
+        struct nfsd4_channel_attrs fore_channel;
+        struct nfsd4_channel_attrs back_channel;
+        u32                     callback_prog;
+        u32                     uid;
+        u32                     gid;
 };
 
 struct nfsd4_sequence {