Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1381 insertions, 0 deletions

diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
new file mode 100644
index 000000000..f5b7ad084
--- /dev/null
+++ b/fs/nfsd/nfs4callback.c
@@ -0,0 +1,1381 @@
+/*
+ *  Copyright (c) 2001 The Regents of the University of Michigan.
+ *  All rights reserved.
+ *
+ *  Kendrick Smith <kmsmith@umich.edu>
+ *  Andy Adamson <andros@umich.edu>
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions
+ *  are met:
+ *
+ *  1. Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *  2. Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *  3. Neither the name of the University nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ *  DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ *  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ *  LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ *  NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/xprt.h>
+#include <linux/sunrpc/svc_xprt.h>
+#include <linux/slab.h>
+#include "nfsd.h"
+#include "state.h"
+#include "netns.h"
+#include "trace.h"
+#include "xdr4cb.h"
+#include "xdr4.h"
+
+#define NFSDDBG_FACILITY                NFSDDBG_PROC
+
+static void nfsd4_mark_cb_fault(struct nfs4_client *, int reason);
+
+#define NFSPROC4_CB_NULL 0
+#define NFSPROC4_CB_COMPOUND 1
+
+/* Index of predefined Linux callback client operations */
+
+struct nfs4_cb_compound_hdr {
+	/* args */
+	u32		ident;	/* minorversion 0 only */
+	u32		nops;
+	__be32		*nops_p;
+	u32		minorversion;
+	/* res */
+	int		status;
+};
+
+static __be32 *xdr_encode_empty_array(__be32 *p)
+{
+	*p++ = xdr_zero;
+	return p;
+}
+
+/*
+ * Encode/decode NFSv4 CB basic data types
+ *
+ * Basic NFSv4 callback data types are defined in section 15 of RFC
+ * 3530: "Network File System (NFS) version 4 Protocol" and section
+ * 20 of RFC 5661: "Network File System (NFS) Version 4 Minor Version
+ * 1 Protocol"
+ */
+
+/*
+ *	nfs_cb_opnum4
+ *
+ *	enum nfs_cb_opnum4 {
+ *		OP_CB_GETATTR		= 3,
+ *		  ...
+ *	};
+ */
+enum nfs_cb_opnum4 {
+	OP_CB_GETATTR			= 3,
+	OP_CB_RECALL			= 4,
+	OP_CB_LAYOUTRECALL		= 5,
+	OP_CB_NOTIFY			= 6,
+	OP_CB_PUSH_DELEG		= 7,
+	OP_CB_RECALL_ANY		= 8,
+	OP_CB_RECALLABLE_OBJ_AVAIL	= 9,
+	OP_CB_RECALL_SLOT		= 10,
+	OP_CB_SEQUENCE			= 11,
+	OP_CB_WANTS_CANCELLED		= 12,
+	OP_CB_NOTIFY_LOCK		= 13,
+	OP_CB_NOTIFY_DEVICEID		= 14,
+	OP_CB_OFFLOAD			= 15,
+	OP_CB_ILLEGAL			= 10044
+};
+
+static void encode_nfs_cb_opnum4(struct xdr_stream *xdr, enum nfs_cb_opnum4 op)
+{
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, 4);
+	*p = cpu_to_be32(op);
+}
+
+/*
+ * nfs_fh4
+ *
+ *	typedef opaque nfs_fh4<NFS4_FHSIZE>;
+ */
+static void encode_nfs_fh4(struct xdr_stream *xdr, const struct knfsd_fh *fh)
+{
+	u32 length = fh->fh_size;
+	__be32 *p;
+
+	BUG_ON(length > NFS4_FHSIZE);
+	p = xdr_reserve_space(xdr, 4 + length);
+	xdr_encode_opaque(p, &fh->fh_base, length);
+}
+
+/*
+ * stateid4
+ *
+ *	struct stateid4 {
+ *		uint32_t	seqid;
+ *		opaque		other[12];
+ *	};
+ */
+static void encode_stateid4(struct xdr_stream *xdr, const stateid_t *sid)
+{
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, NFS4_STATEID_SIZE);
+	*p++ = cpu_to_be32(sid->si_generation);
+	xdr_encode_opaque_fixed(p, &sid->si_opaque, NFS4_STATEID_OTHER_SIZE);
+}
+
+/*
+ * sessionid4
+ *
+ *	typedef opaque sessionid4[NFS4_SESSIONID_SIZE];
+ */
+static void encode_sessionid4(struct xdr_stream *xdr,
+			      const struct nfsd4_session *session)
+{
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, NFS4_MAX_SESSIONID_LEN);
+	xdr_encode_opaque_fixed(p, session->se_sessionid.data,
+					NFS4_MAX_SESSIONID_LEN);
+}
+
+/*
+ * nfsstat4
+ */
+static const struct {
+	int stat;
+	int errno;
+} nfs_cb_errtbl[] = {
+	{ NFS4_OK,		0		},
+	{ NFS4ERR_PERM,		-EPERM		},
+	{ NFS4ERR_NOENT,	-ENOENT		},
+	{ NFS4ERR_IO,		-EIO		},
+	{ NFS4ERR_NXIO,		-ENXIO		},
+	{ NFS4ERR_ACCESS,	-EACCES		},
+	{ NFS4ERR_EXIST,	-EEXIST		},
+	{ NFS4ERR_XDEV,		-EXDEV		},
+	{ NFS4ERR_NOTDIR,	-ENOTDIR	},
+	{ NFS4ERR_ISDIR,	-EISDIR		},
+	{ NFS4ERR_INVAL,	-EINVAL		},
+	{ NFS4ERR_FBIG,		-EFBIG		},
+	{ NFS4ERR_NOSPC,	-ENOSPC		},
+	{ NFS4ERR_ROFS,		-EROFS		},
+	{ NFS4ERR_MLINK,	-EMLINK		},
+	{ NFS4ERR_NAMETOOLONG,	-ENAMETOOLONG	},
+	{ NFS4ERR_NOTEMPTY,	-ENOTEMPTY	},
+	{ NFS4ERR_DQUOT,	-EDQUOT		},
+	{ NFS4ERR_STALE,	-ESTALE		},
+	{ NFS4ERR_BADHANDLE,	-EBADHANDLE	},
+	{ NFS4ERR_BAD_COOKIE,	-EBADCOOKIE	},
+	{ NFS4ERR_NOTSUPP,	-ENOTSUPP	},
+	{ NFS4ERR_TOOSMALL,	-ETOOSMALL	},
+	{ NFS4ERR_SERVERFAULT,	-ESERVERFAULT	},
+	{ NFS4ERR_BADTYPE,	-EBADTYPE	},
+	{ NFS4ERR_LOCKED,	-EAGAIN		},
+	{ NFS4ERR_RESOURCE,	-EREMOTEIO	},
+	{ NFS4ERR_SYMLINK,	-ELOOP		},
+	{ NFS4ERR_OP_ILLEGAL,	-EOPNOTSUPP	},
+	{ NFS4ERR_DEADLOCK,	-EDEADLK	},
+	{ -1,			-EIO		}
+};
+
+/*
+ * If we cannot translate the error, the recovery routines should
+ * handle it.
+ *
+ * Note: remaining NFSv4 error codes have values > 10000, so should
+ * not conflict with native Linux error codes.
+ */
+static int nfs_cb_stat_to_errno(int status)
+{
+	int i;
+
+	for (i = 0; nfs_cb_errtbl[i].stat != -1; i++) {
+		if (nfs_cb_errtbl[i].stat == status)
+			return nfs_cb_errtbl[i].errno;
+	}
+
+	dprintk("NFSD: Unrecognized NFS CB status value: %u\n", status);
+	return -status;
+}
+
+static int decode_cb_op_status(struct xdr_stream *xdr,
+			       enum nfs_cb_opnum4 expected, int *status)
+{
+	__be32 *p;
+	u32 op;
+
+	p = xdr_inline_decode(xdr, 4 + 4);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+	op = be32_to_cpup(p++);
+	if (unlikely(op != expected))
+		goto out_unexpected;
+	*status = nfs_cb_stat_to_errno(be32_to_cpup(p));
+	return 0;
+out_overflow:
+	return -EIO;
+out_unexpected:
+	dprintk("NFSD: Callback server returned operation %d but "
+		"we issued a request for %d\n", op, expected);
+	return -EIO;
+}
+
+/*
+ * CB_COMPOUND4args
+ *
+ *	struct CB_COMPOUND4args {
+ *		utf8str_cs	tag;
+ *		uint32_t	minorversion;
+ *		uint32_t	callback_ident;
+ *		nfs_cb_argop4	argarray<>;
+ *	};
+*/
+static void encode_cb_compound4args(struct xdr_stream *xdr,
+				    struct nfs4_cb_compound_hdr *hdr)
+{
+	__be32 * p;
+
+	p = xdr_reserve_space(xdr, 4 + 4 + 4 + 4);
+	p = xdr_encode_empty_array(p);		/* empty tag */
+	*p++ = cpu_to_be32(hdr->minorversion);
+	*p++ = cpu_to_be32(hdr->ident);
+
+	hdr->nops_p = p;
+	*p = cpu_to_be32(hdr->nops);		/* argarray element count */
+}
+
+/*
+ * Update argarray element count
+ */
+static void encode_cb_nops(struct nfs4_cb_compound_hdr *hdr)
+{
+	BUG_ON(hdr->nops > NFS4_MAX_BACK_CHANNEL_OPS);
+	*hdr->nops_p = cpu_to_be32(hdr->nops);
+}
+
+/*
+ * CB_COMPOUND4res
+ *
+ *	struct CB_COMPOUND4res {
+ *		nfsstat4	status;
+ *		utf8str_cs	tag;
+ *		nfs_cb_resop4	resarray<>;
+ *	};
+ */
+static int decode_cb_compound4res(struct xdr_stream *xdr,
+				  struct nfs4_cb_compound_hdr *hdr)
+{
+	u32 length;
+	__be32 *p;
+
+	p = xdr_inline_decode(xdr, 4 + 4);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+	hdr->status = be32_to_cpup(p++);
+	/* Ignore the tag */
+	length = be32_to_cpup(p++);
+	p = xdr_inline_decode(xdr, length + 4);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+	p += XDR_QUADLEN(length);
+	hdr->nops = be32_to_cpup(p);
+	return 0;
+out_overflow:
+	return -EIO;
+}
+
+/*
+ * CB_RECALL4args
+ *
+ *	struct CB_RECALL4args {
+ *		stateid4	stateid;
+ *		bool		truncate;
+ *		nfs_fh4		fh;
+ *	};
+ */
+static void encode_cb_recall4args(struct xdr_stream *xdr,
+				  const struct nfs4_delegation *dp,
+				  struct nfs4_cb_compound_hdr *hdr)
+{
+	__be32 *p;
+
+	encode_nfs_cb_opnum4(xdr, OP_CB_RECALL);
+	encode_stateid4(xdr, &dp->dl_stid.sc_stateid);
+
+	p = xdr_reserve_space(xdr, 4);
+	*p++ = xdr_zero;			/* truncate */
+
+	encode_nfs_fh4(xdr, &dp->dl_stid.sc_file->fi_fhandle);
+
+	hdr->nops++;
+}
+
+/*
+ * CB_SEQUENCE4args
+ *
+ *	struct CB_SEQUENCE4args {
+ *		sessionid4		csa_sessionid;
+ *		sequenceid4		csa_sequenceid;
+ *		slotid4			csa_slotid;
+ *		slotid4			csa_highest_slotid;
+ *		bool			csa_cachethis;
+ *		referring_call_list4	csa_referring_call_lists<>;
+ *	};
+ */
+static void encode_cb_sequence4args(struct xdr_stream *xdr,
+				    const struct nfsd4_callback *cb,
+				    struct nfs4_cb_compound_hdr *hdr)
+{
+	struct nfsd4_session *session = cb->cb_clp->cl_cb_session;
+	__be32 *p;
+
+	if (hdr->minorversion == 0)
+		return;
+
+	encode_nfs_cb_opnum4(xdr, OP_CB_SEQUENCE);
+	encode_sessionid4(xdr, session);
+
+	p = xdr_reserve_space(xdr, 4 + 4 + 4 + 4 + 4);
+	*p++ = cpu_to_be32(session->se_cb_seq_nr);	/* csa_sequenceid */
+	*p++ = xdr_zero;			/* csa_slotid */
+	*p++ = xdr_zero;			/* csa_highest_slotid */
+	*p++ = xdr_zero;			/* csa_cachethis */
+	xdr_encode_empty_array(p);		/* csa_referring_call_lists */
+
+	hdr->nops++;
+}
+
+/*
+ * CB_SEQUENCE4resok
+ *
+ *	struct CB_SEQUENCE4resok {
+ *		sessionid4	csr_sessionid;
+ *		sequenceid4	csr_sequenceid;
+ *		slotid4		csr_slotid;
+ *		slotid4		csr_highest_slotid;
+ *		slotid4		csr_target_highest_slotid;
+ *	};
+ *
+ *	union CB_SEQUENCE4res switch (nfsstat4 csr_status) {
+ *	case NFS4_OK:
+ *		CB_SEQUENCE4resok	csr_resok4;
+ *	default:
+ *		void;
+ *	};
+ *
+ * Our current back channel implmentation supports a single backchannel
+ * with a single slot.
+ */
+static int decode_cb_sequence4resok(struct xdr_stream *xdr,
+				    struct nfsd4_callback *cb)
+{
+	struct nfsd4_session *session = cb->cb_clp->cl_cb_session;
+	int status = -ESERVERFAULT;
+	__be32 *p;
+	u32 dummy;
+
+	/*
+	 * If the server returns different values for sessionID, slotID or
+	 * sequence number, the server is looney tunes.
+	 */
+	p = xdr_inline_decode(xdr, NFS4_MAX_SESSIONID_LEN + 4 + 4 + 4 + 4);
+	if (unlikely(p == NULL))
+		goto out_overflow;
+
+	if (memcmp(p, session->se_sessionid.data, NFS4_MAX_SESSIONID_LEN)) {
+		dprintk("NFS: %s Invalid session id\n", __func__);
+		goto out;
+	}
+	p += XDR_QUADLEN(NFS4_MAX_SESSIONID_LEN);
+
+	dummy = be32_to_cpup(p++);
+	if (dummy != session->se_cb_seq_nr) {
+		dprintk("NFS: %s Invalid sequence number\n", __func__);
+		goto out;
+	}
+
+	dummy = be32_to_cpup(p++);
+	if (dummy != 0) {
+		dprintk("NFS: %s Invalid slotid\n", __func__);
+		goto out;
+	}
+
+	/*
+	 * FIXME: process highest slotid and target highest slotid
+	 */
+	status = 0;
+out:
+	cb->cb_seq_status = status;
+	return status;
+out_overflow:
+	status = -EIO;
+	goto out;
+}
+
+static int decode_cb_sequence4res(struct xdr_stream *xdr,
+				  struct nfsd4_callback *cb)
+{
+	int status;
+
+	if (cb->cb_clp->cl_minorversion == 0)
+		return 0;
+
+	status = decode_cb_op_status(xdr, OP_CB_SEQUENCE, &cb->cb_seq_status);
+	if (unlikely(status || cb->cb_seq_status))
+		return status;
+
+	return decode_cb_sequence4resok(xdr, cb);
+}
+
+/*
+ * NFSv4.0 and NFSv4.1 XDR encode functions
+ *
+ * NFSv4.0 callback argument types are defined in section 15 of RFC
+ * 3530: "Network File System (NFS) version 4 Protocol" and section 20
+ * of RFC 5661:  "Network File System (NFS) Version 4 Minor Version 1
+ * Protocol".
+ */
+
+/*
+ * NB: Without this zero space reservation, callbacks over krb5p fail
+ */
+static void nfs4_xdr_enc_cb_null(struct rpc_rqst *req, struct xdr_stream *xdr,
+				 const void *__unused)
+{
+	xdr_reserve_space(xdr, 0);
+}
+
+/*
+ * 20.2. Operation 4: CB_RECALL - Recall a Delegation
+ */
+static void nfs4_xdr_enc_cb_recall(struct rpc_rqst *req, struct xdr_stream *xdr,
+				   const void *data)
+{
+	const struct nfsd4_callback *cb = data;
+	const struct nfs4_delegation *dp = cb_to_delegation(cb);
+	struct nfs4_cb_compound_hdr hdr = {
+		.ident = cb->cb_clp->cl_cb_ident,
+		.minorversion = cb->cb_clp->cl_minorversion,
+	};
+
+	encode_cb_compound4args(xdr, &hdr);
+	encode_cb_sequence4args(xdr, cb, &hdr);
+	encode_cb_recall4args(xdr, dp, &hdr);
+	encode_cb_nops(&hdr);
+}
+
+
+/*
+ * NFSv4.0 and NFSv4.1 XDR decode functions
+ *
+ * NFSv4.0 callback result types are defined in section 15 of RFC
+ * 3530: "Network File System (NFS) version 4 Protocol" and section 20
+ * of RFC 5661:  "Network File System (NFS) Version 4 Minor Version 1
+ * Protocol".
+ */
+
+static int nfs4_xdr_dec_cb_null(struct rpc_rqst *req, struct xdr_stream *xdr,
+				void *__unused)
+{
+	return 0;
+}
+
+/*
+ * 20.2. Operation 4: CB_RECALL - Recall a Delegation
+ */
+static int nfs4_xdr_dec_cb_recall(struct rpc_rqst *rqstp,
+				  struct xdr_stream *xdr,
+				  void *data)
+{
+	struct nfsd4_callback *cb = data;
+	struct nfs4_cb_compound_hdr hdr;
+	int status;
+
+	status = decode_cb_compound4res(xdr, &hdr);
+	if (unlikely(status))
+		return status;
+
+	status = decode_cb_sequence4res(xdr, cb);
+	if (unlikely(status || cb->cb_seq_status))
+		return status;
+
+	return decode_cb_op_status(xdr, OP_CB_RECALL, &cb->cb_status);
+}
+
+#ifdef CONFIG_NFSD_PNFS
+/*
+ * CB_LAYOUTRECALL4args
+ *
+ *	struct layoutrecall_file4 {
+ *		nfs_fh4         lor_fh;
+ *		offset4         lor_offset;
+ *		length4         lor_length;
+ *		stateid4        lor_stateid;
+ *	};
+ *
+ *	union layoutrecall4 switch(layoutrecall_type4 lor_recalltype) {
+ *	case LAYOUTRECALL4_FILE:
+ *		layoutrecall_file4 lor_layout;
+ *	case LAYOUTRECALL4_FSID:
+ *		fsid4              lor_fsid;
+ *	case LAYOUTRECALL4_ALL:
+ *		void;
+ *	};
+ *
+ *	struct CB_LAYOUTRECALL4args {
+ *		layouttype4             clora_type;
+ *		layoutiomode4           clora_iomode;
+ *		bool                    clora_changed;
+ *		layoutrecall4           clora_recall;
+ *	};
+ */
+static void encode_cb_layout4args(struct xdr_stream *xdr,
+				  const struct nfs4_layout_stateid *ls,
+				  struct nfs4_cb_compound_hdr *hdr)
+{
+	__be32 *p;
+
+	BUG_ON(hdr->minorversion == 0);
+
+	p = xdr_reserve_space(xdr, 5 * 4);
+	*p++ = cpu_to_be32(OP_CB_LAYOUTRECALL);
+	*p++ = cpu_to_be32(ls->ls_layout_type);
+	*p++ = cpu_to_be32(IOMODE_ANY);
+	*p++ = cpu_to_be32(1);
+	*p = cpu_to_be32(RETURN_FILE);
+
+	encode_nfs_fh4(xdr, &ls->ls_stid.sc_file->fi_fhandle);
+
+	p = xdr_reserve_space(xdr, 2 * 8);
+	p = xdr_encode_hyper(p, 0);
+	xdr_encode_hyper(p, NFS4_MAX_UINT64);
+
+	encode_stateid4(xdr, &ls->ls_recall_sid);
+
+	hdr->nops++;
+}
+
+static void nfs4_xdr_enc_cb_layout(struct rpc_rqst *req,
+				   struct xdr_stream *xdr,
+				   const void *data)
+{
+	const struct nfsd4_callback *cb = data;
+	const struct nfs4_layout_stateid *ls =
+		container_of(cb, struct nfs4_layout_stateid, ls_recall);
+	struct nfs4_cb_compound_hdr hdr = {
+		.ident = 0,
+		.minorversion = cb->cb_clp->cl_minorversion,
+	};
+
+	encode_cb_compound4args(xdr, &hdr);
+	encode_cb_sequence4args(xdr, cb, &hdr);
+	encode_cb_layout4args(xdr, ls, &hdr);
+	encode_cb_nops(&hdr);
+}
+
+static int nfs4_xdr_dec_cb_layout(struct rpc_rqst *rqstp,
+				  struct xdr_stream *xdr,
+				  void *data)
+{
+	struct nfsd4_callback *cb = data;
+	struct nfs4_cb_compound_hdr hdr;
+	int status;
+
+	status = decode_cb_compound4res(xdr, &hdr);
+	if (unlikely(status))
+		return status;
+
+	status = decode_cb_sequence4res(xdr, cb);
+	if (unlikely(status || cb->cb_seq_status))
+		return status;
+
+	return decode_cb_op_status(xdr, OP_CB_LAYOUTRECALL, &cb->cb_status);
+}
+#endif /* CONFIG_NFSD_PNFS */
+
+static void encode_stateowner(struct xdr_stream *xdr, struct nfs4_stateowner *so)
+{
+	__be32	*p;
+
+	p = xdr_reserve_space(xdr, 8 + 4 + so->so_owner.len);
+	p = xdr_encode_opaque_fixed(p, &so->so_client->cl_clientid, 8);
+	xdr_encode_opaque(p, so->so_owner.data, so->so_owner.len);
+}
+
+static void nfs4_xdr_enc_cb_notify_lock(struct rpc_rqst *req,
+					struct xdr_stream *xdr,
+					const void *data)
+{
+	const struct nfsd4_callback *cb = data;
+	const struct nfsd4_blocked_lock *nbl =
+		container_of(cb, struct nfsd4_blocked_lock, nbl_cb);
+	struct nfs4_lockowner *lo = (struct nfs4_lockowner *)nbl->nbl_lock.fl_owner;
+	struct nfs4_cb_compound_hdr hdr = {
+		.ident = 0,
+		.minorversion = cb->cb_clp->cl_minorversion,
+	};
+
+	__be32 *p;
+
+	BUG_ON(hdr.minorversion == 0);
+
+	encode_cb_compound4args(xdr, &hdr);
+	encode_cb_sequence4args(xdr, cb, &hdr);
+
+	p = xdr_reserve_space(xdr, 4);
+	*p = cpu_to_be32(OP_CB_NOTIFY_LOCK);
+	encode_nfs_fh4(xdr, &nbl->nbl_fh);
+	encode_stateowner(xdr, &lo->lo_owner);
+	hdr.nops++;
+
+	encode_cb_nops(&hdr);
+}
+
+static int nfs4_xdr_dec_cb_notify_lock(struct rpc_rqst *rqstp,
+					struct xdr_stream *xdr,
+					void *data)
+{
+	struct nfsd4_callback *cb = data;
+	struct nfs4_cb_compound_hdr hdr;
+	int status;
+
+	status = decode_cb_compound4res(xdr, &hdr);
+	if (unlikely(status))
+		return status;
+
+	status = decode_cb_sequence4res(xdr, cb);
+	if (unlikely(status || cb->cb_seq_status))
+		return status;
+
+	return decode_cb_op_status(xdr, OP_CB_NOTIFY_LOCK, &cb->cb_status);
+}
+
+/*
+ * struct write_response4 {
+ *	stateid4	wr_callback_id<1>;
+ *	length4		wr_count;
+ *	stable_how4	wr_committed;
+ *	verifier4	wr_writeverf;
+ * };
+ * union offload_info4 switch (nfsstat4 coa_status) {
+ *	case NFS4_OK:
+ *		write_response4	coa_resok4;
+ *	default:
+ *	length4		coa_bytes_copied;
+ * };
+ * struct CB_OFFLOAD4args {
+ *	nfs_fh4		coa_fh;
+ *	stateid4	coa_stateid;
+ *	offload_info4	coa_offload_info;
+ * };
+ */
+static void encode_offload_info4(struct xdr_stream *xdr,
+				 __be32 nfserr,
+				 const struct nfsd4_copy *cp)
+{
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, 4);
+	*p++ = nfserr;
+	if (!nfserr) {
+		p = xdr_reserve_space(xdr, 4 + 8 + 4 + NFS4_VERIFIER_SIZE);
+		p = xdr_encode_empty_array(p);
+		p = xdr_encode_hyper(p, cp->cp_res.wr_bytes_written);
+		*p++ = cpu_to_be32(cp->cp_res.wr_stable_how);
+		p = xdr_encode_opaque_fixed(p, cp->cp_res.wr_verifier.data,
+					    NFS4_VERIFIER_SIZE);
+	} else {
+		p = xdr_reserve_space(xdr, 8);
+		/* We always return success if bytes were written */
+		p = xdr_encode_hyper(p, 0);
+	}
+}
+
+static void encode_cb_offload4args(struct xdr_stream *xdr,
+				   __be32 nfserr,
+				   const struct knfsd_fh *fh,
+				   const struct nfsd4_copy *cp,
+				   struct nfs4_cb_compound_hdr *hdr)
+{
+	__be32 *p;
+
+	p = xdr_reserve_space(xdr, 4);
+	*p++ = cpu_to_be32(OP_CB_OFFLOAD);
+	encode_nfs_fh4(xdr, fh);
+	encode_stateid4(xdr, &cp->cp_res.cb_stateid);
+	encode_offload_info4(xdr, nfserr, cp);
+
+	hdr->nops++;
+}
+
+static void nfs4_xdr_enc_cb_offload(struct rpc_rqst *req,
+				    struct xdr_stream *xdr,
+				    const void *data)
+{
+	const struct nfsd4_callback *cb = data;
+	const struct nfsd4_copy *cp =
+		container_of(cb, struct nfsd4_copy, cp_cb);
+	struct nfs4_cb_compound_hdr hdr = {
+		.ident = 0,
+		.minorversion = cb->cb_clp->cl_minorversion,
+	};
+
+	encode_cb_compound4args(xdr, &hdr);
+	encode_cb_sequence4args(xdr, cb, &hdr);
+	encode_cb_offload4args(xdr, cp->nfserr, &cp->fh, cp, &hdr);
+	encode_cb_nops(&hdr);
+}
+
+static int nfs4_xdr_dec_cb_offload(struct rpc_rqst *rqstp,
+				   struct xdr_stream *xdr,
+				   void *data)
+{
+	struct nfsd4_callback *cb = data;
+	struct nfs4_cb_compound_hdr hdr;
+	int status;
+
+	status = decode_cb_compound4res(xdr, &hdr);
+	if (unlikely(status))
+		return status;
+
+	status = decode_cb_sequence4res(xdr, cb);
+	if (unlikely(status || cb->cb_seq_status))
+		return status;
+
+	return decode_cb_op_status(xdr, OP_CB_OFFLOAD, &cb->cb_status);
+}
+/*
+ * RPC procedure tables
+ */
+#define PROC(proc, call, argtype, restype)				\
+[NFSPROC4_CLNT_##proc] = {						\
+	.p_proc    = NFSPROC4_CB_##call,				\
+	.p_encode  = nfs4_xdr_enc_##argtype,		\
+	.p_decode  = nfs4_xdr_dec_##restype,				\
+	.p_arglen  = NFS4_enc_##argtype##_sz,				\
+	.p_replen  = NFS4_dec_##restype##_sz,				\
+	.p_statidx = NFSPROC4_CB_##call,				\
+	.p_name    = #proc,						\
+}
+
+static const struct rpc_procinfo nfs4_cb_procedures[] = {
+	PROC(CB_NULL,	NULL,		cb_null,	cb_null),
+	PROC(CB_RECALL,	COMPOUND,	cb_recall,	cb_recall),
+#ifdef CONFIG_NFSD_PNFS
+	PROC(CB_LAYOUT,	COMPOUND,	cb_layout,	cb_layout),
+#endif
+	PROC(CB_NOTIFY_LOCK,	COMPOUND,	cb_notify_lock,	cb_notify_lock),
+	PROC(CB_OFFLOAD,	COMPOUND,	cb_offload,	cb_offload),
+};
+
+static unsigned int nfs4_cb_counts[ARRAY_SIZE(nfs4_cb_procedures)];
+static const struct rpc_version nfs_cb_version4 = {
+/*
+ * Note on the callback rpc program version number: despite language in rfc
+ * 5661 section 18.36.3 requiring servers to use 4 in this field, the
+ * official xdr descriptions for both 4.0 and 4.1 specify version 1, and
+ * in practice that appears to be what implementations use.  The section
+ * 18.36.3 language is expected to be fixed in an erratum.
+ */
+	.number			= 1,
+	.nrprocs		= ARRAY_SIZE(nfs4_cb_procedures),
+	.procs			= nfs4_cb_procedures,
+	.counts			= nfs4_cb_counts,
+};
+
+static const struct rpc_version *nfs_cb_version[2] = {
+	[1] = &nfs_cb_version4,
+};
+
+static const struct rpc_program cb_program;
+
+static struct rpc_stat cb_stats = {
+	.program		= &cb_program
+};
+
+#define NFS4_CALLBACK 0x40000000
+static const struct rpc_program cb_program = {
+	.name			= "nfs4_cb",
+	.number			= NFS4_CALLBACK,
+	.nrvers			= ARRAY_SIZE(nfs_cb_version),
+	.version		= nfs_cb_version,
+	.stats			= &cb_stats,
+	.pipe_dir_name		= "nfsd4_cb",
+};
+
+static int max_cb_time(struct net *net)
+{
+	struct nfsd_net *nn = net_generic(net, nfsd_net_id);
+
+	/*
+	 * nfsd4_lease is set to at most one hour in __nfsd4_write_time,
+	 * so we can use 32-bit math on it. Warn if that assumption
+	 * ever stops being true.
+	 */
+	if (WARN_ON_ONCE(nn->nfsd4_lease > 3600))
+		return 360 * HZ;
+
+	return max(((u32)nn->nfsd4_lease)/10, 1u) * HZ;
+}
+
+static struct workqueue_struct *callback_wq;
+
+static bool nfsd4_queue_cb(struct nfsd4_callback *cb)
+{
+	return queue_work(callback_wq, &cb->cb_work);
+}
+
+static void nfsd41_cb_inflight_begin(struct nfs4_client *clp)
+{
+	atomic_inc(&clp->cl_cb_inflight);
+}
+
+static void nfsd41_cb_inflight_end(struct nfs4_client *clp)
+{
+
+	if (atomic_dec_and_test(&clp->cl_cb_inflight))
+		wake_up_var(&clp->cl_cb_inflight);
+}
+
+static void nfsd41_cb_inflight_wait_complete(struct nfs4_client *clp)
+{
+	wait_var_event(&clp->cl_cb_inflight,
+			!atomic_read(&clp->cl_cb_inflight));
+}
+
+static const struct cred *get_backchannel_cred(struct nfs4_client *clp, struct rpc_clnt *client, struct nfsd4_session *ses)
+{
+	if (clp->cl_minorversion == 0) {
+		client->cl_principal = clp->cl_cred.cr_targ_princ ?
+			clp->cl_cred.cr_targ_princ : "nfs";
+
+		return get_cred(rpc_machine_cred());
+	} else {
+		struct cred *kcred;
+
+		kcred = prepare_kernel_cred(NULL);
+		if (!kcred)
+			return NULL;
+
+		kcred->fsuid = ses->se_cb_sec.uid;
+		kcred->fsgid = ses->se_cb_sec.gid;
+		return kcred;
+	}
+}
+
+static int setup_callback_client(struct nfs4_client *clp, struct nfs4_cb_conn *conn, struct nfsd4_session *ses)
+{
+	int maxtime = max_cb_time(clp->net);
+	struct rpc_timeout	timeparms = {
+		.to_initval	= maxtime,
+		.to_retries	= 0,
+		.to_maxval	= maxtime,
+	};
+	struct rpc_create_args args = {
+		.net		= clp->net,
+		.address	= (struct sockaddr *) &conn->cb_addr,
+		.addrsize	= conn->cb_addrlen,
+		.saddress	= (struct sockaddr *) &conn->cb_saddr,
+		.timeout	= &timeparms,
+		.program	= &cb_program,
+		.version	= 1,
+		.flags		= (RPC_CLNT_CREATE_NOPING | RPC_CLNT_CREATE_QUIET),
+		.cred		= current_cred(),
+	};
+	struct rpc_clnt *client;
+	const struct cred *cred;
+
+	if (clp->cl_minorversion == 0) {
+		if (!clp->cl_cred.cr_principal &&
+		    (clp->cl_cred.cr_flavor >= RPC_AUTH_GSS_KRB5)) {
+			trace_nfsd_cb_setup_err(clp, -EINVAL);
+			return -EINVAL;
+		}
+		args.client_name = clp->cl_cred.cr_principal;
+		args.prognumber	= conn->cb_prog;
+		args.protocol = XPRT_TRANSPORT_TCP;
+		args.authflavor = clp->cl_cred.cr_flavor;
+		clp->cl_cb_ident = conn->cb_ident;
+	} else {
+		if (!conn->cb_xprt)
+			return -EINVAL;
+		clp->cl_cb_session = ses;
+		args.bc_xprt = conn->cb_xprt;
+		args.prognumber = clp->cl_cb_session->se_cb_prog;
+		args.protocol = conn->cb_xprt->xpt_class->xcl_ident |
+				XPRT_TRANSPORT_BC;
+		args.authflavor = ses->se_cb_sec.flavor;
+	}
+	/* Create RPC client */
+	client = rpc_create(&args);
+	if (IS_ERR(client)) {
+		trace_nfsd_cb_setup_err(clp, PTR_ERR(client));
+		return PTR_ERR(client);
+	}
+	cred = get_backchannel_cred(clp, client, ses);
+	if (!cred) {
+		trace_nfsd_cb_setup_err(clp, -ENOMEM);
+		rpc_shutdown_client(client);
+		return -ENOMEM;
+	}
+
+	if (clp->cl_minorversion != 0)
+		clp->cl_cb_conn.cb_xprt = conn->cb_xprt;
+	clp->cl_cb_client = client;
+	clp->cl_cb_cred = cred;
+	trace_nfsd_cb_setup(clp);
+	return 0;
+}
+
+static void nfsd4_mark_cb_down(struct nfs4_client *clp, int reason)
+{
+	if (test_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags))
+		return;
+	clp->cl_cb_state = NFSD4_CB_DOWN;
+	trace_nfsd_cb_state(clp);
+}
+
+static void nfsd4_mark_cb_fault(struct nfs4_client *clp, int reason)
+{
+	if (test_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags))
+		return;
+	clp->cl_cb_state = NFSD4_CB_FAULT;
+	trace_nfsd_cb_state(clp);
+}
+
+static void nfsd4_cb_probe_done(struct rpc_task *task, void *calldata)
+{
+	struct nfs4_client *clp = container_of(calldata, struct nfs4_client, cl_cb_null);
+
+	trace_nfsd_cb_done(clp, task->tk_status);
+	if (task->tk_status)
+		nfsd4_mark_cb_down(clp, task->tk_status);
+	else {
+		clp->cl_cb_state = NFSD4_CB_UP;
+		trace_nfsd_cb_state(clp);
+	}
+}
+
+static void nfsd4_cb_probe_release(void *calldata)
+{
+	struct nfs4_client *clp = container_of(calldata, struct nfs4_client, cl_cb_null);
+
+	nfsd41_cb_inflight_end(clp);
+
+}
+
+static const struct rpc_call_ops nfsd4_cb_probe_ops = {
+	/* XXX: release method to ensure we set the cb channel down if
+	 * necessary on early failure? */
+	.rpc_call_done = nfsd4_cb_probe_done,
+	.rpc_release = nfsd4_cb_probe_release,
+};
+
+/*
+ * Poke the callback thread to process any updates to the callback
+ * parameters, and send a null probe.
+ */
+void nfsd4_probe_callback(struct nfs4_client *clp)
+{
+	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
+	trace_nfsd_cb_state(clp);
+	set_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags);
+	nfsd4_run_cb(&clp->cl_cb_null);
+}
+
+void nfsd4_probe_callback_sync(struct nfs4_client *clp)
+{
+	nfsd4_probe_callback(clp);
+	flush_workqueue(callback_wq);
+}
+
+void nfsd4_change_callback(struct nfs4_client *clp, struct nfs4_cb_conn *conn)
+{
+	clp->cl_cb_state = NFSD4_CB_UNKNOWN;
+	spin_lock(&clp->cl_lock);
+	memcpy(&clp->cl_cb_conn, conn, sizeof(struct nfs4_cb_conn));
+	spin_unlock(&clp->cl_lock);
+	trace_nfsd_cb_state(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 bool nfsd41_cb_get_slot(struct nfsd4_callback *cb, struct rpc_task *task)
+{
+	struct nfs4_client *clp = cb->cb_clp;
+
+	if (!cb->cb_holds_slot &&
+	    test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
+		rpc_sleep_on(&clp->cl_cb_waitq, task, NULL);
+		/* Race breaker */
+		if (test_and_set_bit(0, &clp->cl_cb_slot_busy) != 0) {
+			dprintk("%s slot is busy\n", __func__);
+			return false;
+		}
+		rpc_wake_up_queued_task(&clp->cl_cb_waitq, task);
+	}
+	cb->cb_holds_slot = true;
+	return true;
+}
+
+static void nfsd41_cb_release_slot(struct nfsd4_callback *cb)
+{
+	struct nfs4_client *clp = cb->cb_clp;
+
+	if (cb->cb_holds_slot) {
+		cb->cb_holds_slot = false;
+		clear_bit(0, &clp->cl_cb_slot_busy);
+		rpc_wake_up_next(&clp->cl_cb_waitq);
+	}
+}
+
+static void nfsd41_destroy_cb(struct nfsd4_callback *cb)
+{
+	struct nfs4_client *clp = cb->cb_clp;
+
+	nfsd41_cb_release_slot(cb);
+	if (cb->cb_ops && cb->cb_ops->release)
+		cb->cb_ops->release(cb);
+	nfsd41_cb_inflight_end(clp);
+}
+
+/*
+ * 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 nfsd4_callback *cb = calldata;
+	struct nfs4_client *clp = cb->cb_clp;
+	u32 minorversion = clp->cl_minorversion;
+
+	/*
+	 * cb_seq_status is only set in decode_cb_sequence4res,
+	 * and so will remain 1 if an rpc level failure occurs.
+	 */
+	cb->cb_seq_status = 1;
+	cb->cb_status = 0;
+	if (minorversion && !nfsd41_cb_get_slot(cb, task))
+		return;
+	rpc_call_start(task);
+}
+
+static bool nfsd4_cb_sequence_done(struct rpc_task *task, struct nfsd4_callback *cb)
+{
+	struct nfs4_client *clp = cb->cb_clp;
+	struct nfsd4_session *session = clp->cl_cb_session;
+	bool ret = true;
+
+	if (!clp->cl_minorversion) {
+		/*
+		 * If the backchannel connection was shut down while this
+		 * task was queued, we need to resubmit it after setting up
+		 * a new backchannel connection.
+		 *
+		 * Note that if we lost our callback connection permanently
+		 * the submission code will error out, so we don't need to
+		 * handle that case here.
+		 */
+		if (RPC_SIGNALLED(task))
+			goto need_restart;
+
+		return true;
+	}
+
+	if (!cb->cb_holds_slot)
+		goto need_restart;
+
+	switch (cb->cb_seq_status) {
+	case 0:
+		/*
+		 * No need for lock, access serialized in nfsd4_cb_prepare
+		 *
+		 * RFC5661 20.9.3
+		 * If CB_SEQUENCE returns an error, then the state of the slot
+		 * (sequence ID, cached reply) MUST NOT change.
+		 */
+		++session->se_cb_seq_nr;
+		break;
+	case -ESERVERFAULT:
+		++session->se_cb_seq_nr;
+		fallthrough;
+	case 1:
+	case -NFS4ERR_BADSESSION:
+		nfsd4_mark_cb_fault(cb->cb_clp, cb->cb_seq_status);
+		ret = false;
+		break;
+	case -NFS4ERR_DELAY:
+		if (!rpc_restart_call(task))
+			goto out;
+
+		rpc_delay(task, 2 * HZ);
+		return false;
+	case -NFS4ERR_BADSLOT:
+		goto retry_nowait;
+	case -NFS4ERR_SEQ_MISORDERED:
+		if (session->se_cb_seq_nr != 1) {
+			session->se_cb_seq_nr = 1;
+			goto retry_nowait;
+		}
+		break;
+	default:
+		nfsd4_mark_cb_fault(cb->cb_clp, cb->cb_seq_status);
+		dprintk("%s: unprocessed error %d\n", __func__,
+			cb->cb_seq_status);
+	}
+
+	nfsd41_cb_release_slot(cb);
+	dprintk("%s: freed slot, new seqid=%d\n", __func__,
+		clp->cl_cb_session->se_cb_seq_nr);
+
+	if (RPC_SIGNALLED(task))
+		goto need_restart;
+out:
+	return ret;
+retry_nowait:
+	if (rpc_restart_call_prepare(task))
+		ret = false;
+	goto out;
+need_restart:
+	if (!test_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags)) {
+		task->tk_status = 0;
+		cb->cb_need_restart = true;
+	}
+	return false;
+}
+
+static void nfsd4_cb_done(struct rpc_task *task, void *calldata)
+{
+	struct nfsd4_callback *cb = calldata;
+	struct nfs4_client *clp = cb->cb_clp;
+
+	trace_nfsd_cb_done(clp, task->tk_status);
+
+	if (!nfsd4_cb_sequence_done(task, cb))
+		return;
+
+	if (cb->cb_status) {
+		WARN_ON_ONCE(task->tk_status);
+		task->tk_status = cb->cb_status;
+	}
+
+	switch (cb->cb_ops->done(cb, task)) {
+	case 0:
+		task->tk_status = 0;
+		rpc_restart_call_prepare(task);
+		return;
+	case 1:
+		switch (task->tk_status) {
+		case -EIO:
+		case -ETIMEDOUT:
+		case -EACCES:
+			nfsd4_mark_cb_down(clp, task->tk_status);
+		}
+		break;
+	default:
+		BUG();
+	}
+}
+
+static void nfsd4_cb_release(void *calldata)
+{
+	struct nfsd4_callback *cb = calldata;
+
+	if (cb->cb_need_restart)
+		nfsd4_queue_cb(cb);
+	else
+		nfsd41_destroy_cb(cb);
+
+}
+
+static const struct rpc_call_ops nfsd4_cb_ops = {
+	.rpc_call_prepare = nfsd4_cb_prepare,
+	.rpc_call_done = nfsd4_cb_done,
+	.rpc_release = nfsd4_cb_release,
+};
+
+int nfsd4_create_callback_queue(void)
+{
+	callback_wq = alloc_ordered_workqueue("nfsd4_callbacks", 0);
+	if (!callback_wq)
+		return -ENOMEM;
+	return 0;
+}
+
+void nfsd4_destroy_callback_queue(void)
+{
+	destroy_workqueue(callback_wq);
+}
+
+/* must be called under the state lock */
+void nfsd4_shutdown_callback(struct nfs4_client *clp)
+{
+	set_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags);
+	/*
+	 * Note this won't actually result in a null callback;
+	 * instead, nfsd4_run_cb_null() will detect the killed
+	 * client, destroy the rpc client, and stop:
+	 */
+	nfsd4_run_cb(&clp->cl_cb_null);
+	flush_workqueue(callback_wq);
+	nfsd41_cb_inflight_wait_complete(clp);
+}
+
+/* requires cl_lock: */
+static struct nfsd4_conn * __nfsd4_find_backchannel(struct nfs4_client *clp)
+{
+	struct nfsd4_session *s;
+	struct nfsd4_conn *c;
+
+	list_for_each_entry(s, &clp->cl_sessions, se_perclnt) {
+		list_for_each_entry(c, &s->se_conns, cn_persession) {
+			if (c->cn_flags & NFS4_CDFC4_BACK)
+				return c;
+		}
+	}
+	return NULL;
+}
+
+/*
+ * Note there isn't a lot of locking in this code; instead we depend on
+ * the fact that it is run from the callback_wq, which won't run two
+ * work items at once.  So, for example, callback_wq handles all access
+ * of cl_cb_client and all calls to rpc_create or rpc_shutdown_client.
+ */
+static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
+{
+	struct nfs4_cb_conn conn;
+	struct nfs4_client *clp = cb->cb_clp;
+	struct nfsd4_session *ses = NULL;
+	struct nfsd4_conn *c;
+	int err;
+
+	/*
+	 * This is either an update, or the client dying; in either case,
+	 * kill the old client:
+	 */
+	if (clp->cl_cb_client) {
+		trace_nfsd_cb_shutdown(clp);
+		rpc_shutdown_client(clp->cl_cb_client);
+		clp->cl_cb_client = NULL;
+		put_cred(clp->cl_cb_cred);
+		clp->cl_cb_cred = NULL;
+	}
+	if (clp->cl_cb_conn.cb_xprt) {
+		svc_xprt_put(clp->cl_cb_conn.cb_xprt);
+		clp->cl_cb_conn.cb_xprt = NULL;
+	}
+	if (test_bit(NFSD4_CLIENT_CB_KILL, &clp->cl_flags))
+		return;
+	spin_lock(&clp->cl_lock);
+	/*
+	 * Only serialized callback code is allowed to clear these
+	 * flags; main nfsd code can only set them:
+	 */
+	BUG_ON(!(clp->cl_flags & NFSD4_CLIENT_CB_FLAG_MASK));
+	clear_bit(NFSD4_CLIENT_CB_UPDATE, &clp->cl_flags);
+	memcpy(&conn, &cb->cb_clp->cl_cb_conn, sizeof(struct nfs4_cb_conn));
+	c = __nfsd4_find_backchannel(clp);
+	if (c) {
+		svc_xprt_get(c->cn_xprt);
+		conn.cb_xprt = c->cn_xprt;
+		ses = c->cn_session;
+	}
+	spin_unlock(&clp->cl_lock);
+
+	err = setup_callback_client(clp, &conn, ses);
+	if (err) {
+		nfsd4_mark_cb_down(clp, err);
+		if (c)
+			svc_xprt_put(c->cn_xprt);
+		return;
+	}
+}
+
+static void
+nfsd4_run_cb_work(struct work_struct *work)
+{
+	struct nfsd4_callback *cb =
+		container_of(work, struct nfsd4_callback, cb_work);
+	struct nfs4_client *clp = cb->cb_clp;
+	struct rpc_clnt *clnt;
+	int flags;
+
+	trace_nfsd_cb_work(clp, cb->cb_msg.rpc_proc->p_name);
+
+	if (cb->cb_need_restart) {
+		cb->cb_need_restart = false;
+	} else {
+		if (cb->cb_ops && cb->cb_ops->prepare)
+			cb->cb_ops->prepare(cb);
+	}
+
+	if (clp->cl_flags & NFSD4_CLIENT_CB_FLAG_MASK)
+		nfsd4_process_cb_update(cb);
+
+	clnt = clp->cl_cb_client;
+	if (!clnt) {
+		/* Callback channel broken, or client killed; give up: */
+		nfsd41_destroy_cb(cb);
+		return;
+	}
+
+	/*
+	 * Don't send probe messages for 4.1 or later.
+	 */
+	if (!cb->cb_ops && clp->cl_minorversion) {
+		clp->cl_cb_state = NFSD4_CB_UP;
+		nfsd41_destroy_cb(cb);
+		return;
+	}
+
+	cb->cb_msg.rpc_cred = clp->cl_cb_cred;
+	flags = clp->cl_minorversion ? RPC_TASK_NOCONNECT : RPC_TASK_SOFTCONN;
+	rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT | flags,
+			cb->cb_ops ? &nfsd4_cb_ops : &nfsd4_cb_probe_ops, cb);
+}
+
+void nfsd4_init_cb(struct nfsd4_callback *cb, struct nfs4_client *clp,
+		const struct nfsd4_callback_ops *ops, enum nfsd4_cb_op op)
+{
+	cb->cb_clp = clp;
+	cb->cb_msg.rpc_proc = &nfs4_cb_procedures[op];
+	cb->cb_msg.rpc_argp = cb;
+	cb->cb_msg.rpc_resp = cb;
+	cb->cb_ops = ops;
+	INIT_WORK(&cb->cb_work, nfsd4_run_cb_work);
+	cb->cb_seq_status = 1;
+	cb->cb_status = 0;
+	cb->cb_need_restart = false;
+	cb->cb_holds_slot = false;
+}
+
+void nfsd4_run_cb(struct nfsd4_callback *cb)
+{
+	struct nfs4_client *clp = cb->cb_clp;
+
+	nfsd41_cb_inflight_begin(clp);
+	if (!nfsd4_queue_cb(cb))
+		nfsd41_cb_inflight_end(clp);
+}