Merge branch 'for-2.6.32' of git://linux-nfs.org/~bfields/linux

* 'for-2.6.32' of git://linux-nfs.org/~bfields/linux: (68 commits)
  nfsd4: nfsv4 clients should cross mountpoints
  nfsd: revise 4.1 status documentation
  sunrpc/cache: avoid variable over-loading in cache_defer_req
  sunrpc/cache: use list_del_init for the list_head entries in cache_deferred_req
  nfsd: return success for non-NFS4 nfs4_state_start
  nfsd41: Refactor create_client()
  nfsd41: modify nfsd4.1 backchannel to use new xprt class
  nfsd41: Backchannel: Implement cb_recall over NFSv4.1
  nfsd41: Backchannel: cb_sequence callback
  nfsd41: Backchannel: Setup sequence information
  nfsd41: Backchannel: Server backchannel RPC wait queue
  nfsd41: Backchannel: Add sequence arguments to callback RPC arguments
  nfsd41: Backchannel: callback infrastructure
  nfsd4: use common rpc_cred for all callbacks
  nfsd4: allow nfs4 state startup to fail
  SUNRPC: Defer the auth_gss upcall when the RPC call is asynchronous
  nfsd4: fix null dereference creating nfsv4 callback client
  nfsd4: fix whitespace in NFSPROC4_CLNT_CB_NULL definition
  nfsd41: sunrpc: add new xprt class for nfsv4.1 backchannel
  sunrpc/cache: simplify cache_fresh_locked and cache_fresh_unlocked.
  ...

42 files changed, 1640 insertions, 897 deletions

diff --git a/Documentation/filesystems/nfs41-server.txt b/Documentation/filesystems/nfs41-server.txt
index 05d81cbcb2e1..5920fe26e6ff 100644
--- a/Documentation/filesystems/nfs41-server.txt
+++ b/Documentation/filesystems/nfs41-server.txt
@@ -11,6 +11,11 @@ the /proc/fs/nfsd/versions control file.  Note that to write this
 control file, the nfsd service must be taken down.  Use your user-mode
 nfs-utils to set this up; see rpc.nfsd(8)
 
+(Warning: older servers will interpret "+4.1" and "-4.1" as "+4" and
+"-4", respectively.  Therefore, code meant to work on both new and old
+kernels must turn 4.1 on or off *before* turning support for version 4
+on or off; rpc.nfsd does this correctly.)
+
 The NFSv4 minorversion 1 (NFSv4.1) implementation in nfsd is based
 on the latest NFSv4.1 Internet Draft:
 http://tools.ietf.org/html/draft-ietf-nfsv4-minorversion1-29
@@ -25,6 +30,49 @@ are still under development out of tree.
 See http://wiki.linux-nfs.org/wiki/index.php/PNFS_prototype_design
 for more information.
 
+The current implementation is intended for developers only: while it
+does support ordinary file operations on clients we have tested against
+(including the linux client), it is incomplete in ways which may limit
+features unexpectedly, cause known bugs in rare cases, or cause
+interoperability problems with future clients.  Known issues:
+
+	- gss support is questionable: currently mounts with kerberos
+	  from a linux client are possible, but we aren't really
+	  conformant with the spec (for example, we don't use kerberos
+	  on the backchannel correctly).
+	- no trunking support: no clients currently take advantage of
+	  trunking, but this is a mandatory failure, and its use is
+	  recommended to clients in a number of places.  (E.g. to ensure
+	  timely renewal in case an existing connection's retry timeouts
+	  have gotten too long; see section 8.3 of the draft.)
+	  Therefore, lack of this feature may cause future clients to
+	  fail.
+	- Incomplete backchannel support: incomplete backchannel gss
+	  support and no support for BACKCHANNEL_CTL mean that
+	  callbacks (hence delegations and layouts) may not be
+	  available and clients confused by the incomplete
+	  implementation may fail.
+	- Server reboot recovery is unsupported; if the server reboots,
+	  clients may fail.
+	- We do not support SSV, which provides security for shared
+	  client-server state (thus preventing unauthorized tampering
+	  with locks and opens, for example).  It is mandatory for
+	  servers to support this, though no clients use it yet.
+	- Mandatory operations which we do not support, such as
+	  DESTROY_CLIENTID, FREE_STATEID, SECINFO_NO_NAME, and
+	  TEST_STATEID, are not currently used by clients, but will be
+	  (and the spec recommends their uses in common cases), and
+	  clients should not be expected to know how to recover from the
+	  case where they are not supported.  This will eventually cause
+	  interoperability failures.
+
+In addition, some limitations are inherited from the current NFSv4
+implementation:
+
+	- Incomplete delegation enforcement: if a file is renamed or
+	  unlinked, a client holding a delegation may continue to
+	  indefinitely allow opens of the file under the old name.
+
 The table below, taken from the NFSv4.1 document, lists
 the operations that are mandatory to implement (REQ), optional
 (OPT), and NFSv4.0 operations that are required not to implement (MNI)
@@ -142,6 +190,12 @@ NS*| CB_WANTS_CANCELLED      | OPT       | FDELG,      | Section 20.10 |
 
 Implementation notes:
 
+DELEGPURGE:
+* mandatory only for servers that support CLAIM_DELEGATE_PREV and/or
+  CLAIM_DELEG_PREV_FH (which allows clients to keep delegations that
+  persist across client reboots).  Thus we need not implement this for
+  now.
+
 EXCHANGE_ID:
 * only SP4_NONE state protection supported
 * implementation ids are ignored
diff --git a/fs/lockd/clntlock.c b/fs/lockd/clntlock.c
index 1f3b0fc0d351..fc9032dc8862 100644
--- a/fs/lockd/clntlock.c
+++ b/fs/lockd/clntlock.c
@@ -166,7 +166,7 @@ __be32 nlmclnt_grant(const struct sockaddr *addr, const struct nlm_lock *lock)
 		 */
 		if (fl_blocked->fl_u.nfs_fl.owner->pid != lock->svid)
 			continue;
-		if (!nlm_cmp_addr(nlm_addr(block->b_host), addr))
+		if (!rpc_cmp_addr(nlm_addr(block->b_host), addr))
 			continue;
 		if (nfs_compare_fh(NFS_FH(fl_blocked->fl_file->f_path.dentry->d_inode) ,fh) != 0)
 			continue;
diff --git a/fs/lockd/host.c b/fs/lockd/host.c
index 7cb076ac6b45..4600c2037b8b 100644
--- a/fs/lockd/host.c
+++ b/fs/lockd/host.c
@@ -111,7 +111,7 @@ static struct nlm_host *nlm_lookup_host(struct nlm_lookup_host_info *ni)
 	 */
 	chain = &nlm_hosts[nlm_hash_address(ni->sap)];
 	hlist_for_each_entry(host, pos, chain, h_hash) {
-		if (!nlm_cmp_addr(nlm_addr(host), ni->sap))
+		if (!rpc_cmp_addr(nlm_addr(host), ni->sap))
 			continue;
 
 		/* See if we have an NSM handle for this client */
@@ -125,7 +125,7 @@ static struct nlm_host *nlm_lookup_host(struct nlm_lookup_host_info *ni)
 		if (host->h_server != ni->server)
 			continue;
 		if (ni->server &&
-		    !nlm_cmp_addr(nlm_srcaddr(host), ni->src_sap))
+		    !rpc_cmp_addr(nlm_srcaddr(host), ni->src_sap))
 			continue;
 
 		/* Move to head of hash chain. */
diff --git a/fs/lockd/mon.c b/fs/lockd/mon.c
index 30c933188dd7..f956651d0f65 100644
--- a/fs/lockd/mon.c
+++ b/fs/lockd/mon.c
@@ -209,7 +209,7 @@ static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
 	struct nsm_handle *nsm;
 
 	list_for_each_entry(nsm, &nsm_handles, sm_link)
-		if (nlm_cmp_addr(nsm_addr(nsm), sap))
+		if (rpc_cmp_addr(nsm_addr(nsm), sap))
 			return nsm;
 	return NULL;
 }
diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
index 9e4d6aab611b..ad478da7ca63 100644
--- a/fs/lockd/svcsubs.c
+++ b/fs/lockd/svcsubs.c
@@ -417,7 +417,7 @@ EXPORT_SYMBOL_GPL(nlmsvc_unlock_all_by_sb);
 static int
 nlmsvc_match_ip(void *datap, struct nlm_host *host)
 {
-	return nlm_cmp_addr(nlm_srcaddr(host), datap);
+	return rpc_cmp_addr(nlm_srcaddr(host), datap);
 }
 
 /**
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index d9462643155c..984a5ebcc1d6 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -1341,6 +1341,8 @@ exp_pseudoroot(struct svc_rqst *rqstp, struct svc_fh *fhp)
 	if (rv)
 		goto out;
 	rv = check_nfsd_access(exp, rqstp);
+	if (rv)
+		fh_put(fhp);
 out:
 	exp_put(exp);
 	return rv;
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 01d4ec1c88e0..edf926e1062f 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -814,17 +814,6 @@ encode_entry_baggage(struct nfsd3_readdirres *cd, __be32 *p, const char *name,
 	return p;
 }
 
-static __be32 *
-encode_entryplus_baggage(struct nfsd3_readdirres *cd, __be32 *p,
-		struct svc_fh *fhp)
-{
-	p = encode_post_op_attr(cd->rqstp, p, fhp);
-	*p++ = xdr_one;			/* yes, a file handle follows */
-	p = encode_fh(p, fhp);
-	fh_put(fhp);
-	return p;
-}
-
 static int
 compose_entry_fh(struct nfsd3_readdirres *cd, struct svc_fh *fhp,
 		const char *name, int namlen)
@@ -836,29 +825,54 @@ compose_entry_fh(struct nfsd3_readdirres *cd, struct svc_fh *fhp,
 	dparent = cd->fh.fh_dentry;
 	exp  = cd->fh.fh_export;
 
-	fh_init(fhp, NFS3_FHSIZE);
 	if (isdotent(name, namlen)) {
 		if (namlen == 2) {
 			dchild = dget_parent(dparent);
 			if (dchild == dparent) {
 				/* filesystem root - cannot return filehandle for ".." */
 				dput(dchild);
-				return 1;
+				return -ENOENT;
 			}
 		} else
 			dchild = dget(dparent);
 	} else
 		dchild = lookup_one_len(name, dparent, namlen);
 	if (IS_ERR(dchild))
-		return 1;
-	if (d_mountpoint(dchild) ||
-	    fh_compose(fhp, exp, dchild, &cd->fh) != 0 ||
-	    !dchild->d_inode)
-		rv = 1;
+		return -ENOENT;
+	rv = -ENOENT;
+	if (d_mountpoint(dchild))
+		goto out;
+	rv = fh_compose(fhp, exp, dchild, &cd->fh);
+	if (rv)
+		goto out;
+	if (!dchild->d_inode)
+		goto out;
+	rv = 0;
+out:
 	dput(dchild);
 	return rv;
 }
 
+__be32 *encode_entryplus_baggage(struct nfsd3_readdirres *cd, __be32 *p, const char *name, int namlen)
+{
+	struct svc_fh	fh;
+	int err;
+
+	fh_init(&fh, NFS3_FHSIZE);
+	err = compose_entry_fh(cd, &fh, name, namlen);
+	if (err) {
+		*p++ = 0;
+		*p++ = 0;
+		goto out;
+	}
+	p = encode_post_op_attr(cd->rqstp, p, &fh);
+	*p++ = xdr_one;			/* yes, a file handle follows */
+	p = encode_fh(p, &fh);
+out:
+	fh_put(&fh);
+	return p;
+}
+
 /*
  * Encode a directory entry. This one works for both normal readdir
  * and readdirplus.
@@ -929,16 +943,8 @@ encode_entry(struct readdir_cd *ccd, const char *name, int namlen,
 
 		p = encode_entry_baggage(cd, p, name, namlen, ino);
 
-		/* throw in readdirplus baggage */
-		if (plus) {
-			struct svc_fh	fh;
-
-			if (compose_entry_fh(cd, &fh, name, namlen) > 0) {
-				*p++ = 0;
-				*p++ = 0;
-			} else
-				p = encode_entryplus_baggage(cd, p, &fh);
-		}
+		if (plus)
+			p = encode_entryplus_baggage(cd, p, name, namlen);
 		num_entry_words = p - cd->buffer;
 	} else if (cd->rqstp->rq_respages[pn+1] != NULL) {
 		/* temporarily encode entry into next page, then move back to
@@ -951,17 +957,8 @@ encode_entry(struct readdir_cd *ccd, const char *name, int namlen,
 
 		p1 = encode_entry_baggage(cd, p1, name, namlen, ino);
 
-		/* throw in readdirplus baggage */
-		if (plus) {
-			struct svc_fh	fh;
-
-			if (compose_entry_fh(cd, &fh, name, namlen) > 0) {
-				/* zero out the filehandle */
-				*p1++ = 0;
-				*p1++ = 0;
-			} else
-				p1 = encode_entryplus_baggage(cd, p1, &fh);
-		}
+		if (plus)
+			p = encode_entryplus_baggage(cd, p1, name, namlen);
 
 		/* determine entry word length and lengths to go in pages */
 		num_entry_words = p1 - tmp;
diff --git a/fs/nfsd/nfs4acl.c b/fs/nfsd/nfs4acl.c
index 54b8b4140c8f..725d02f210e2 100644
--- a/fs/nfsd/nfs4acl.c
+++ b/fs/nfsd/nfs4acl.c
@@ -321,7 +321,7 @@ _posix_to_nfsv4_one(struct posix_acl *pacl, struct nfs4_acl *acl,
 	deny = ~pas.group & pas.other;
 	if (deny) {
 		ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
-		ace->flag = eflag | NFS4_ACE_IDENTIFIER_GROUP;
+		ace->flag = eflag;
 		ace->access_mask = deny_mask_from_posix(deny, flags);
 		ace->whotype = NFS4_ACL_WHO_GROUP;
 		ace++;
@@ -335,7 +335,7 @@ _posix_to_nfsv4_one(struct posix_acl *pacl, struct nfs4_acl *acl,
 		if (deny) {
 			ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
 			ace->flag = eflag | NFS4_ACE_IDENTIFIER_GROUP;
-			ace->access_mask = mask_from_posix(deny, flags);
+			ace->access_mask = deny_mask_from_posix(deny, flags);
 			ace->whotype = NFS4_ACL_WHO_NAMED;
 			ace->who = pa->e_id;
 			ace++;
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 3fd23f7aceca..24e8d78f8dde 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -43,25 +43,30 @@
 #include <linux/sunrpc/xdr.h>
 #include <linux/sunrpc/svc.h>
 #include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/svcsock.h>
 #include <linux/nfsd/nfsd.h>
 #include <linux/nfsd/state.h>
 #include <linux/sunrpc/sched.h>
 #include <linux/nfs4.h>
+#include <linux/sunrpc/xprtsock.h>
 
 #define NFSDDBG_FACILITY                NFSDDBG_PROC
 
 #define NFSPROC4_CB_NULL 0
 #define NFSPROC4_CB_COMPOUND 1
+#define NFS4_STATEID_SIZE 16
 
 /* Index of predefined Linux callback client operations */
 
 enum {
-        NFSPROC4_CLNT_CB_NULL = 0,
+	NFSPROC4_CLNT_CB_NULL = 0,
 	NFSPROC4_CLNT_CB_RECALL,
+	NFSPROC4_CLNT_CB_SEQUENCE,
 };
 
 enum nfs_cb_opnum4 {
 	OP_CB_RECALL            = 4,
+	OP_CB_SEQUENCE          = 11,
 };
 
 #define NFS4_MAXTAGLEN		20
@@ -70,17 +75,29 @@ enum nfs_cb_opnum4 {
 #define NFS4_dec_cb_null_sz		0
 #define cb_compound_enc_hdr_sz		4
 #define cb_compound_dec_hdr_sz		(3 + (NFS4_MAXTAGLEN >> 2))
+#define sessionid_sz			(NFS4_MAX_SESSIONID_LEN >> 2)
+#define cb_sequence_enc_sz		(sessionid_sz + 4 +             \
+					1 /* no referring calls list yet */)
+#define cb_sequence_dec_sz		(op_dec_sz + sessionid_sz + 4)
+
 #define op_enc_sz			1
 #define op_dec_sz			2
 #define enc_nfs4_fh_sz			(1 + (NFS4_FHSIZE >> 2))
 #define enc_stateid_sz			(NFS4_STATEID_SIZE >> 2)
 #define NFS4_enc_cb_recall_sz		(cb_compound_enc_hdr_sz +       \
+					cb_sequence_enc_sz +            \
 					1 + enc_stateid_sz +            \
 					enc_nfs4_fh_sz)
 
 #define NFS4_dec_cb_recall_sz		(cb_compound_dec_hdr_sz  +      \
+					cb_sequence_dec_sz +            \
 					op_dec_sz)
 
+struct nfs4_rpc_args {
+	void				*args_op;
+	struct nfsd4_cb_sequence	args_seq;
+};
+
 /*
 * Generic encode routines from fs/nfs/nfs4xdr.c
 */
@@ -137,11 +154,13 @@ xdr_error:                                      \
 } while (0)
 
 struct nfs4_cb_compound_hdr {
-	int		status;
-	u32		ident;
+	/* args */
+	u32		ident;	/* minorversion 0 only */
 	u32		nops;
 	__be32		*nops_p;
 	u32		minorversion;
+	/* res */
+	int		status;
 	u32		taglen;
 	char		*tag;
 };
@@ -238,6 +257,27 @@ encode_cb_recall(struct xdr_stream *xdr, struct nfs4_delegation *dp,
 	hdr->nops++;
 }
 
+static void
+encode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *args,
+		   struct nfs4_cb_compound_hdr *hdr)
+{
+	__be32 *p;
+
+	if (hdr->minorversion == 0)
+		return;
+
+	RESERVE_SPACE(1 + NFS4_MAX_SESSIONID_LEN + 20);
+
+	WRITE32(OP_CB_SEQUENCE);
+	WRITEMEM(args->cbs_clp->cl_sessionid.data, NFS4_MAX_SESSIONID_LEN);
+	WRITE32(args->cbs_clp->cl_cb_seq_nr);
+	WRITE32(0);		/* slotid, always 0 */
+	WRITE32(0);		/* highest slotid always 0 */
+	WRITE32(0);		/* cachethis always 0 */
+	WRITE32(0); /* FIXME: support referring_call_lists */
+	hdr->nops++;
+}
+
 static int
 nfs4_xdr_enc_cb_null(struct rpc_rqst *req, __be32 *p)
 {
@@ -249,15 +289,19 @@ nfs4_xdr_enc_cb_null(struct rpc_rqst *req, __be32 *p)
 }
 
 static int
-nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p, struct nfs4_delegation *args)
+nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, __be32 *p,
+		struct nfs4_rpc_args *rpc_args)
 {
 	struct xdr_stream xdr;
+	struct nfs4_delegation *args = rpc_args->args_op;
 	struct nfs4_cb_compound_hdr hdr = {
 		.ident = args->dl_ident,
+		.minorversion = rpc_args->args_seq.cbs_minorversion,
 	};
 
 	xdr_init_encode(&xdr, &req->rq_snd_buf, p);
 	encode_cb_compound_hdr(&xdr, &hdr);
+	encode_cb_sequence(&xdr, &rpc_args->args_seq, &hdr);
 	encode_cb_recall(&xdr, args, &hdr);
 	encode_cb_nops(&hdr);
 	return 0;
@@ -299,6 +343,57 @@ decode_cb_op_hdr(struct xdr_stream *xdr, enum nfs_opnum4 expected)
 	return 0;
 }
 
+/*
+ * Our current back channel implmentation supports a single backchannel
+ * with a single slot.
+ */
+static int
+decode_cb_sequence(struct xdr_stream *xdr, struct nfsd4_cb_sequence *res,
+		   struct rpc_rqst *rqstp)
+{
+	struct nfs4_sessionid id;
+	int status;
+	u32 dummy;
+	__be32 *p;
+
+	if (res->cbs_minorversion == 0)
+		return 0;
+
+	status = decode_cb_op_hdr(xdr, OP_CB_SEQUENCE);
+	if (status)
+		return status;
+
+	/*
+	 * If the server returns different values for sessionID, slotID or
+	 * sequence number, the server is looney tunes.
+	 */
+	status = -ESERVERFAULT;
+
+	READ_BUF(NFS4_MAX_SESSIONID_LEN + 16);
+	memcpy(id.data, p, NFS4_MAX_SESSIONID_LEN);
+	p += XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN);
+	if (memcmp(id.data, res->cbs_clp->cl_sessionid.data,
+		   NFS4_MAX_SESSIONID_LEN)) {
+		dprintk("%s Invalid session id\n", __func__);
+		goto out;
+	}
+	READ32(dummy);
+	if (dummy != res->cbs_clp->cl_cb_seq_nr) {
+		dprintk("%s Invalid sequence number\n", __func__);
+		goto out;
+	}
+	READ32(dummy); 	/* slotid must be 0 */
+	if (dummy != 0) {
+		dprintk("%s Invalid slotid\n", __func__);
+		goto out;
+	}
+	/* FIXME: process highest slotid and target highest slotid */
+	status = 0;
+out:
+	return status;
+}
+
+
 static int
 nfs4_xdr_dec_cb_null(struct rpc_rqst *req, __be32 *p)
 {
@@ -306,7 +401,8 @@ nfs4_xdr_dec_cb_null(struct rpc_rqst *req, __be32 *p)
 }
 
 static int
-nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p)
+nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p,
+		struct nfsd4_cb_sequence *seq)
 {
 	struct xdr_stream xdr;
 	struct nfs4_cb_compound_hdr hdr;
@@ -316,6 +412,11 @@ nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp, __be32 *p)
 	status = decode_cb_compound_hdr(&xdr, &hdr);
 	if (status)
 		goto out;
+	if (seq) {
+		status = decode_cb_sequence(&xdr, seq, rqstp);
+		if (status)
+			goto out;
+	}
 	status = decode_cb_op_hdr(&xdr, OP_CB_RECALL);
 out:
 	return status;
@@ -377,16 +478,15 @@ static int max_cb_time(void)
 
 int setup_callback_client(struct nfs4_client *clp)
 {
-	struct sockaddr_in	addr;
 	struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
 	struct rpc_timeout	timeparms = {
 		.to_initval	= max_cb_time(),
 		.to_retries	= 0,
 	};
 	struct rpc_create_args args = {
-		.protocol	= IPPROTO_TCP,
-		.address	= (struct sockaddr *)&addr,
-		.addrsize	= sizeof(addr),
+		.protocol	= XPRT_TRANSPORT_TCP,
+		.address	= (struct sockaddr *) &cb->cb_addr,
+		.addrsize	= cb->cb_addrlen,
 		.timeout	= &timeparms,
 		.program	= &cb_program,
 		.prognumber	= cb->cb_prog,
@@ -399,13 +499,10 @@ int setup_callback_client(struct nfs4_client *clp)
 
 	if (!clp->cl_principal && (clp->cl_flavor >= RPC_AUTH_GSS_KRB5))
 		return -EINVAL;
-
-	/* Initialize address */
-	memset(&addr, 0, sizeof(addr));
-	addr.sin_family = AF_INET;
-	addr.sin_port = htons(cb->cb_port);
-	addr.sin_addr.s_addr = htonl(cb->cb_addr);
-
+	if (cb->cb_minorversion) {
+		args.bc_xprt = clp->cl_cb_xprt;
+		args.protocol = XPRT_TRANSPORT_BC_TCP;
+	}
 	/* Create RPC client */
 	client = rpc_create(&args);
 	if (IS_ERR(client)) {
@@ -439,42 +536,29 @@ static const struct rpc_call_ops nfsd4_cb_probe_ops = {
 	.rpc_call_done = nfsd4_cb_probe_done,
 };
 
-static struct rpc_cred *lookup_cb_cred(struct nfs4_cb_conn *cb)
-{
-	struct auth_cred acred = {
-		.machine_cred = 1
-	};
+static struct rpc_cred *callback_cred;
 
-	/*
-	 * Note in the gss case this doesn't actually have to wait for a
-	 * gss upcall (or any calls to the client); this just creates a
-	 * non-uptodate cred which the rpc state machine will fill in with
-	 * a refresh_upcall later.
-	 */
-	return rpcauth_lookup_credcache(cb->cb_client->cl_auth, &acred,
-							RPCAUTH_LOOKUP_NEW);
+int set_callback_cred(void)
+{
+	callback_cred = rpc_lookup_machine_cred();
+	if (!callback_cred)
+		return -ENOMEM;
+	return 0;
 }
 
+
 void do_probe_callback(struct nfs4_client *clp)
 {
 	struct nfs4_cb_conn *cb = &clp->cl_cb_conn;
 	struct rpc_message msg = {
 		.rpc_proc       = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_NULL],
 		.rpc_argp       = clp,
+		.rpc_cred	= callback_cred
 	};
-	struct rpc_cred *cred;
 	int status;
 
-	cred = lookup_cb_cred(cb);
-	if (IS_ERR(cred)) {
-		status = PTR_ERR(cred);
-		goto out;
-	}
-	cb->cb_cred = cred;
-	msg.rpc_cred = cb->cb_cred;
 	status = rpc_call_async(cb->cb_client, &msg, RPC_TASK_SOFT,
 				&nfsd4_cb_probe_ops, (void *)clp);
-out:
 	if (status) {
 		warn_no_callback_path(clp, status);
 		put_nfs4_client(clp);
@@ -503,11 +587,95 @@ nfsd4_probe_callback(struct nfs4_client *clp)
 	do_probe_callback(clp);
 }
 
+/*
+ * There's currently a single callback channel slot.
+ * If the slot is available, then mark it busy.  Otherwise, set the
+ * thread for sleeping on the callback RPC wait queue.
+ */
+static int nfsd41_cb_setup_sequence(struct nfs4_client *clp,
+		struct rpc_task *task)
+{
+	struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
+	u32 *ptr = (u32 *)clp->cl_sessionid.data;
+	int status = 0;
+
+	dprintk("%s: %u:%u:%u:%u\n", __func__,
+		ptr[0], ptr[1], ptr[2], ptr[3]);
+
+	if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
+		rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
+		dprintk("%s slot is busy\n", __func__);
+		status = -EAGAIN;
+		goto out;
+	}
+
+	/*
+	 * We'll need the clp during XDR encoding and decoding,
+	 * and the sequence during decoding to verify the reply
+	 */
+	args->args_seq.cbs_clp = clp;
+	task->tk_msg.rpc_resp = &args->args_seq;
+
+out:
+	dprintk("%s status=%d\n", __func__, status);
+	return status;
+}
+
+/*
+ * TODO: cb_sequence should support referring call lists, cachethis, multiple
+ * slots, and mark callback channel down on communication errors.
+ */
+static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
+{
+	struct nfs4_delegation *dp = calldata;
+	struct nfs4_client *clp = dp->dl_client;
+	struct nfs4_rpc_args *args = task->tk_msg.rpc_argp;
+	u32 minorversion = clp->cl_cb_conn.cb_minorversion;
+	int status = 0;
+
+	args->args_seq.cbs_minorversion = minorversion;
+	if (minorversion) {
+		status = nfsd41_cb_setup_sequence(clp, task);
+		if (status) {
+			if (status != -EAGAIN) {
+				/* terminate rpc task */
+				task->tk_status = status;
+				task->tk_action = NULL;
+			}
+			return;
+		}
+	}
+	rpc_call_start(task);
+}
+
+static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
+{
+	struct nfs4_delegation *dp = calldata;
+	struct nfs4_client *clp = dp->dl_client;
+
+	dprintk("%s: minorversion=%d\n", __func__,
+		clp->cl_cb_conn.cb_minorversion);
+
+	if (clp->cl_cb_conn.cb_minorversion) {
+		/* No need for lock, access serialized in nfsd4_cb_prepare */
+		++clp->cl_cb_seq_nr;
+		clear_bit(0, &clp->cl_cb_slot_busy);
+		rpc_wake_up_next(&clp->cl_cb_waitq);
+		dprintk("%s: freed slot, new seqid=%d\n", __func__,
+			clp->cl_cb_seq_nr);
+
+		/* We're done looking into the sequence information */
+		task->tk_msg.rpc_resp = NULL;
+	}
+}
+
 static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
 {
 	struct nfs4_delegation *dp = calldata;
 	struct nfs4_client *clp = dp->dl_client;
 
+	nfsd4_cb_done(task, calldata);
+
 	switch (task->tk_status) {
 	case -EIO:
 		/* Network partition? */
@@ -520,16 +688,19 @@ static void nfsd4_cb_recall_done(struct rpc_task *task, void *calldata)
 		break;
 	default:
 		/* success, or error we can't handle */
-		return;
+		goto done;
 	}
 	if (dp->dl_retries--) {
 		rpc_delay(task, 2*HZ);
 		task->tk_status = 0;
 		rpc_restart_call(task);
+		return;
 	} else {
 		atomic_set(&clp->cl_cb_conn.cb_set, 0);
 		warn_no_callback_path(clp, task->tk_status);
 	}
+done:
+	kfree(task->tk_msg.rpc_argp);
 }
 
 static void nfsd4_cb_recall_release(void *calldata)
@@ -542,6 +713,7 @@ static void nfsd4_cb_recall_release(void *calldata)
 }
 
 static const struct rpc_call_ops nfsd4_cb_recall_ops = {
+	.rpc_call_prepare = nfsd4_cb_prepare,
 	.rpc_call_done = nfsd4_cb_recall_done,
 	.rpc_release = nfsd4_cb_recall_release,
 };
@@ -554,17 +726,24 @@ nfsd4_cb_recall(struct nfs4_delegation *dp)
 {
 	struct nfs4_client *clp = dp->dl_client;
 	struct rpc_clnt *clnt = clp->cl_cb_conn.cb_client;
+	struct nfs4_rpc_args *args;
 	struct rpc_message msg = {
 		.rpc_proc = &nfs4_cb_procedures[NFSPROC4_CLNT_CB_RECALL],
-		.rpc_argp = dp,
-		.rpc_cred = clp->cl_cb_conn.cb_cred
+		.rpc_cred = callback_cred
 	};
-	int status;
+	int status = -ENOMEM;
 
+	args = kzalloc(sizeof(*args), GFP_KERNEL);
+	if (!args)
+		goto out;
+	args->args_op = dp;
+	msg.rpc_argp = args;
 	dp->dl_retries = 1;
 	status = rpc_call_async(clnt, &msg, RPC_TASK_SOFT,
 				&nfsd4_cb_recall_ops, dp);
+out:
 	if (status) {
+		kfree(args);
 		put_nfs4_client(clp);
 		nfs4_put_delegation(dp);
 	}
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 7c8801769a3c..bebc0c2e1b0a 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -68,7 +68,6 @@ check_attr_support(struct svc_rqst *rqstp, struct n