NFS refactor nfs_find_client and reference client across callback processing

Fixes a bug where the nfs_client could be freed during callback processing.
Refactor nfs_find_client to use minorversion specific means to locate the
correct nfs_client structure.

In the NFS layer, V4.0 clients are found using the callback_ident field in the
CB_COMPOUND header.  V4.1 clients are found using the sessionID in the
CB_SEQUENCE operation which is also compared against the sessionID associated
with the back channel thread after a successful CREATE_SESSION.

Each of these methods finds the one an only nfs_client associated
with the incoming callback request - so nfs_find_client_next is not needed.

In the RPC layer, the pg_authenticate call needs to find the nfs_client. For
the v4.0 callback service, the callback identifier has not been decoded so a
search by address, version, and minorversion is used.  The sessionid for the
sessions based callback service has (usually) not been set for the
pg_authenticate on a CB_NULL call which can be sent prior to the return
of a CREATE_SESSION call, so the sessionid associated with the back channel
thread is not used to find the client in pg_authenticate for CB_NULL calls.

Pass the referenced nfs_client to each CB_COMPOUND operation being proceesed
via the new cb_process_state structure. The reference is held across
cb_compound processing.

Use the new cb_process_state struct to move the NFS4ERR_RETRY_UNCACHED_REP
processing from process_op into nfs4_callback_sequence where it belongs.

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

1 files changed, 24 insertions, 15 deletions

diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index 05af212f0edf..dbd0d649805c 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -10,8 +10,10 @@
 #include <linux/nfs4.h>
 #include <linux/nfs_fs.h>
 #include <linux/slab.h>
+#include <linux/sunrpc/bc_xprt.h>
 #include "nfs4_fs.h"
 #include "callback.h"
+#include "internal.h"
 
 #define CB_OP_TAGLEN_MAXSZ      (512)
 #define CB_OP_HDR_RES_MAXSZ     (2 + CB_OP_TAGLEN_MAXSZ)
@@ -33,7 +35,8 @@
 /* Internal error code */
 #define NFS4ERR_RESOURCE_HDR    11050
 
-typedef __be32 (*callback_process_op_t)(void *, void *);
+typedef __be32 (*callback_process_op_t)(void *, void *,
+                                        struct cb_process_state *);
 typedef __be32 (*callback_decode_arg_t)(struct svc_rqst *, struct xdr_stream *, void *);
 typedef __be32 (*callback_encode_res_t)(struct svc_rqst *, struct xdr_stream *, void *);
 
@@ -160,7 +163,7 @@ static __be32 decode_compound_hdr_arg(struct xdr_stream *xdr, struct cb_compound
         hdr->minorversion = ntohl(*p++);
         /* Check minor version is zero or one. */
         if (hdr->minorversion <= 1) {
-                p++;    /* skip callback_ident */
+                hdr->cb_ident = ntohl(*p++); /* ignored by v4.1 */
         } else {
                 printk(KERN_WARNING "%s: NFSv4 server callback with "
                         "illegal minor version %u!\n",
@@ -621,7 +624,8 @@ preprocess_nfs4_op(unsigned int op_nr, struct callback_op **op)
 static __be32 process_op(uint32_t minorversion, int nop,
                 struct svc_rqst *rqstp,
                 struct xdr_stream *xdr_in, void *argp,
-                struct xdr_stream *xdr_out, void *resp, int* drc_status)
+                struct xdr_stream *xdr_out, void *resp,
+                struct cb_process_state *cps)
 {
         struct callback_op *op = &callback_ops[0];
         unsigned int op_nr;
@@ -644,8 +648,8 @@ static __be32 process_op(uint32_t minorversion, int nop,
         if (status)
                 goto encode_hdr;
 
-        if (*drc_status) {
-                status = *drc_status;
+        if (cps->drc_status) {
+                status = cps->drc_status;
                 goto encode_hdr;
         }
 
@@ -653,16 +657,10 @@ static __be32 process_op(uint32_t minorversion, int nop,
         if (maxlen > 0 && maxlen < PAGE_SIZE) {
                 status = op->decode_args(rqstp, xdr_in, argp);
                 if (likely(status == 0))
-                        status = op->process_op(argp, resp);
+                        status = op->process_op(argp, resp, cps);
         } else
                 status = htonl(NFS4ERR_RESOURCE);
 
-        /* Only set by OP_CB_SEQUENCE processing */
-        if (status == htonl(NFS4ERR_RETRY_UNCACHED_REP)) {
-                *drc_status = status;
-                status = 0;
-        }
-
 encode_hdr:
         res = encode_op_hdr(xdr_out, op_nr, status);
         if (unlikely(res))
@@ -681,8 +679,11 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
         struct cb_compound_hdr_arg hdr_arg = { 0 };
         struct cb_compound_hdr_res hdr_res = { NULL };
         struct xdr_stream xdr_in, xdr_out;
-        __be32 *p;
-        __be32 status, drc_status = 0;
+        __be32 *p, status;
+        struct cb_process_state cps = {
+                .drc_status = 0,
+                .clp = NULL,
+        };
         unsigned int nops = 0;
 
         dprintk("%s: start\n", __func__);
@@ -696,6 +697,13 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
         if (status == __constant_htonl(NFS4ERR_RESOURCE))
                 return rpc_garbage_args;
 
+        if (hdr_arg.minorversion == 0) {
+                cps.clp = nfs4_find_client_ident(hdr_arg.cb_ident);
+                if (!cps.clp)
+                        return rpc_drop_reply;
+        } else
+                cps.svc_sid = bc_xprt_sid(rqstp);
+
         hdr_res.taglen = hdr_arg.taglen;
         hdr_res.tag = hdr_arg.tag;
         if (encode_compound_hdr_res(&xdr_out, &hdr_res) != 0)
@@ -703,7 +711,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
 
         while (status == 0 && nops != hdr_arg.nops) {
                 status = process_op(hdr_arg.minorversion, nops, rqstp,
-                                    &xdr_in, argp, &xdr_out, resp, &drc_status);
+                                    &xdr_in, argp, &xdr_out, resp, &cps);
                 nops++;
         }
 
@@ -716,6 +724,7 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
 
         *hdr_res.status = status;
         *hdr_res.nops = htonl(nops);
+        nfs_put_client(cps.clp);
         dprintk("%s: done, status = %u\n", __func__, ntohl(status));
         return rpc_success;
 }