[pnfs] sequence xdr fix

[dean hildebrand]

Here is a quick patch which removes duplicate sequence xdr allocations
from all operations using sessions.  With this patch, our read
performance increases 10x since the data doesn't need to be copied on
the client after it is received.

This is something we can talk about at the bakeathon, but for now I
removed the global variable nr_sequence_quads and just set the buffer
sizes statically. We need to develop an approach that will support
NFSv4.0 and NFSv4.1.



Description:
    Eliminate duplicate response xdr headers for NFSv4.1 operations
    with regards to sequence id space.  For now, I just made every
    static and used the xdr constants from the top of nfs4xdr.c.
    Eliminated global variable nr_sequence_quads to allow a more
    flexible approach in the future that will support NFSv4.0 and
    NFSv4.1.  We still need to separate out xdr header sizes between
    NFSv4.0 and NFSv4.1.


diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 6e620ea..9dcd97b 100644
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -60,7 +60,6 @@ #define NFSDBG_FACILITY               NFSDBG_XDR

 /* Mapping from NFS error code to "errno" error code. */
 #define errno_NFSERR_IO                EIO
-static int nr_sequence_quads = 0;

 static int nfs_stat_to_errno(int);

@@ -198,7 +197,7 @@ #define NFS4_enc_readlink_sz        (compound_e
 #define NFS4_dec_readlink_sz   (compound_decode_hdr_maxsz + \
                                decode_sequence_maxsz + \
                                decode_putfh_maxsz + \
-                               op_decode_hdr_maxsz)
+                               op_decode_hdr_maxsz + 1)
 #define NFS4_enc_readdir_sz    (compound_encode_hdr_maxsz + \
                                encode_sequence_maxsz +\
                                encode_putfh_maxsz + \
@@ -1300,10 +1299,9 @@ static int encode_readdir(struct xdr_str
        /* set up reply kvec
         *    toplevel_status + taglen + rescount + OP_PUTFH + status
         *      + OP_READDIR + status + verifer(2)  = 9
-        *      Add to this the size for the sequence op; 0 if no sessions,
-        *      11 otherwise
+        * TODO: Session sequence space is statically added.
         */
-       replen = (RPC_REPHDRSIZE + auth->au_rslack + 9 +
nr_sequence_quads) << 2;
+       replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS4_dec_readdir_sz) << 2;
        xdr_inline_pages(&req->rq_rcv_buf, replen, readdir->pages,
                         readdir->pgbase, readdir->count);
        dprintk("%s: inlined page args = (%u, %p, %u, %u)\n",
@@ -1325,9 +1323,9 @@ static int encode_readlink(struct xdr_st
        /* set up reply kvec
         *    toplevel_status + taglen + rescount + OP_PUTFH + status
         *      + OP_READLINK + status + string length = 8
-        *      Similar to readdir, add space for the sequence op
+        * TODO: Session sequence space is statically added.
         */
-       replen = (RPC_REPHDRSIZE + auth->au_rslack + 8 +
nr_sequence_quads) << 2;
+       replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS4_dec_readlink_sz) << 2;
        xdr_inline_pages(&req->rq_rcv_buf, replen, readlink->pages,
                        readlink->pgbase, readlink->pglen);

@@ -2626,9 +2624,9 @@ static int nfs4_xdr_enc_read(struct rpc_
        /* set up reply kvec
         *    toplevel status + taglen=0 + rescount + OP_PUTFH + status
         *       + OP_READ + status + eof + datalen = 9
-        *       Add space for sequence op too.
+        * TODO: Session sequence space is statically added.
         */
-       replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS4_dec_read_sz +
nr_sequence_quads) << 2;
+       replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS4_dec_read_sz) << 2;
        xdr_inline_pages(&req->rq_rcv_buf, replen,
                         args->pages, args->pgbase, args->count);
 out:
@@ -2729,8 +2727,10 @@ nfs4_xdr_enc_getacl(struct rpc_rqst *req
        if (status)
                goto out;
        status = encode_getattr_two(xdr, FATTR4_WORD0_ACL, 0);
-       /* set up reply buffer: */
-       replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS4_dec_getacl_sz +
nr_sequence_quads) << 2;
+       /* set up reply buffer:
+        * TODO: Session sequence space is statically added.
+        */
+       replen = (RPC_REPHDRSIZE + auth->au_rslack + NFS4_dec_getacl_sz) << 2;
        xdr_inline_pages(&req->rq_rcv_buf, replen,
                args->acl_pages, args->acl_pgbase, args->acl_len);
 out:
@@ -3246,8 +3246,9 @@ static int nfs4_xdr_enc_fs_locations(str
        /* set up reply
         *   toplevel_status + OP_PUTFH + status
         *   + OP_LOOKUP + status + OP_GETATTR + status = 7
+        * TODO: Session sequence space is statically added.
         */
-       replen = (RPC_REPHDRSIZE + auth->au_rslack + 7 +
nr_sequence_quads) << 2;
+       replen = (RPC_REPHDRSIZE + auth->au_rslack +
NFS4_dec_fs_locations_sz) << 2;
        xdr_inline_pages(&req->rq_rcv_buf, replen, &args->page,
                        0, PAGE_SIZE);
 out:
@@ -6761,10 +6762,6 @@ static int nfs41_xdr_dec_create_session(

        status = decode_create_session(&xdr, res);

-       if (!status) {
-               /* Decode session succeeded; set nr_sequence_quads */
-               nr_sequence_quads = decode_sequence_maxsz;
-       }
        return status;
 }