diff --git a/fs/nfs/callback_proc.c b/fs/nfs/callback_proc.c
new file mode 100644
index 0000000..fc775b0
--- /dev/null
+++ b/fs/nfs/callback_proc.c
@@ -0,0 +1,737 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/nfs/callback_proc.c
+ *
+ * Copyright (C) 2004 Trond Myklebust
+ *
+ * NFSv4 callback procedures
+ */
+#include <linux/nfs4.h>
+#include <linux/nfs_fs.h>
+#include <linux/slab.h>
+#include <linux/rcupdate.h>
+#include "nfs4_fs.h"
+#include "callback.h"
+#include "delegation.h"
+#include "internal.h"
+#include "pnfs.h"
+#include "nfs4session.h"
+#include "nfs4trace.h"
+
+#define NFSDBG_FACILITY NFSDBG_CALLBACK
+
+__be32 nfs4_callback_getattr(void *argp, void *resp,
+			     struct cb_process_state *cps)
+{
+	struct cb_getattrargs *args = argp;
+	struct cb_getattrres *res = resp;
+	struct nfs_delegation *delegation;
+	struct nfs_inode *nfsi;
+	struct inode *inode;
+
+	res->status = htonl(NFS4ERR_OP_NOT_IN_SESSION);
+	if (!cps->clp) /* Always set for v4.0. Set in cb_sequence for v4.1 */
+		goto out;
+
+	res->bitmap[0] = res->bitmap[1] = 0;
+	res->status = htonl(NFS4ERR_BADHANDLE);
+
+	dprintk_rcu("NFS: GETATTR callback request from %s\n",
+		rpc_peeraddr2str(cps->clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+
+	inode = nfs_delegation_find_inode(cps->clp, &args->fh);
+	if (IS_ERR(inode)) {
+		if (inode == ERR_PTR(-EAGAIN))
+			res->status = htonl(NFS4ERR_DELAY);
+		trace_nfs4_cb_getattr(cps->clp, &args->fh, NULL,
+				-ntohl(res->status));
+		goto out;
+	}
+	nfsi = NFS_I(inode);
+	rcu_read_lock();
+	delegation = rcu_dereference(nfsi->delegation);
+	if (delegation == NULL || (delegation->type & FMODE_WRITE) == 0)
+		goto out_iput;
+	res->size = i_size_read(inode);
+	res->change_attr = delegation->change_attr;
+	if (nfs_have_writebacks(inode))
+		res->change_attr++;
+	res->ctime = timespec64_to_timespec(inode->i_ctime);
+	res->mtime = timespec64_to_timespec(inode->i_mtime);
+	res->bitmap[0] = (FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE) &
+		args->bitmap[0];
+	res->bitmap[1] = (FATTR4_WORD1_TIME_METADATA|FATTR4_WORD1_TIME_MODIFY) &
+		args->bitmap[1];
+	res->status = 0;
+out_iput:
+	rcu_read_unlock();
+	trace_nfs4_cb_getattr(cps->clp, &args->fh, inode, -ntohl(res->status));
+	nfs_iput_and_deactive(inode);
+out:
+	dprintk("%s: exit with status = %d\n", __func__, ntohl(res->status));
+	return res->status;
+}
+
+__be32 nfs4_callback_recall(void *argp, void *resp,
+			    struct cb_process_state *cps)
+{
+	struct cb_recallargs *args = argp;
+	struct inode *inode;
+	__be32 res;
+	
+	res = htonl(NFS4ERR_OP_NOT_IN_SESSION);
+	if (!cps->clp) /* Always set for v4.0. Set in cb_sequence for v4.1 */
+		goto out;
+
+	dprintk_rcu("NFS: RECALL callback request from %s\n",
+		rpc_peeraddr2str(cps->clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+
+	res = htonl(NFS4ERR_BADHANDLE);
+	inode = nfs_delegation_find_inode(cps->clp, &args->fh);
+	if (IS_ERR(inode)) {
+		if (inode == ERR_PTR(-EAGAIN))
+			res = htonl(NFS4ERR_DELAY);
+		trace_nfs4_cb_recall(cps->clp, &args->fh, NULL,
+				&args->stateid, -ntohl(res));
+		goto out;
+	}
+	/* Set up a helper thread to actually return the delegation */
+	switch (nfs_async_inode_return_delegation(inode, &args->stateid)) {
+	case 0:
+		res = 0;
+		break;
+	case -ENOENT:
+		res = htonl(NFS4ERR_BAD_STATEID);
+		break;
+	default:
+		res = htonl(NFS4ERR_RESOURCE);
+	}
+	trace_nfs4_cb_recall(cps->clp, &args->fh, inode,
+			&args->stateid, -ntohl(res));
+	nfs_iput_and_deactive(inode);
+out:
+	dprintk("%s: exit with status = %d\n", __func__, ntohl(res));
+	return res;
+}
+
+#if defined(CONFIG_NFS_V4_1)
+
+/*
+ * Lookup a layout inode by stateid
+ *
+ * Note: returns a refcount on the inode and superblock
+ */
+static struct inode *nfs_layout_find_inode_by_stateid(struct nfs_client *clp,
+		const nfs4_stateid *stateid)
+{
+	struct nfs_server *server;
+	struct inode *inode;
+	struct pnfs_layout_hdr *lo;
+
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+		list_for_each_entry(lo, &server->layouts, plh_layouts) {
+			if (!pnfs_layout_is_valid(lo))
+				continue;
+			if (stateid != NULL &&
+			    !nfs4_stateid_match_other(stateid, &lo->plh_stateid))
+				continue;
+			inode = igrab(lo->plh_inode);
+			if (!inode)
+				return ERR_PTR(-EAGAIN);
+			if (!nfs_sb_active(inode->i_sb)) {
+				rcu_read_unlock();
+				spin_unlock(&clp->cl_lock);
+				iput(inode);
+				spin_lock(&clp->cl_lock);
+				rcu_read_lock();
+				return ERR_PTR(-EAGAIN);
+			}
+			return inode;
+		}
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+/*
+ * Lookup a layout inode by filehandle.
+ *
+ * Note: returns a refcount on the inode and superblock
+ *
+ */
+static struct inode *nfs_layout_find_inode_by_fh(struct nfs_client *clp,
+		const struct nfs_fh *fh)
+{
+	struct nfs_server *server;
+	struct nfs_inode *nfsi;
+	struct inode *inode;
+	struct pnfs_layout_hdr *lo;
+
+	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
+		list_for_each_entry(lo, &server->layouts, plh_layouts) {
+			nfsi = NFS_I(lo->plh_inode);
+			if (nfs_compare_fh(fh, &nfsi->fh))
+				continue;
+			if (nfsi->layout != lo)
+				continue;
+			inode = igrab(lo->plh_inode);
+			if (!inode)
+				return ERR_PTR(-EAGAIN);
+			if (!nfs_sb_active(inode->i_sb)) {
+				rcu_read_unlock();
+				spin_unlock(&clp->cl_lock);
+				iput(inode);
+				spin_lock(&clp->cl_lock);
+				rcu_read_lock();
+				return ERR_PTR(-EAGAIN);
+			}
+			return inode;
+		}
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+static struct inode *nfs_layout_find_inode(struct nfs_client *clp,
+		const struct nfs_fh *fh,
+		const nfs4_stateid *stateid)
+{
+	struct inode *inode;
+
+	spin_lock(&clp->cl_lock);
+	rcu_read_lock();
+	inode = nfs_layout_find_inode_by_stateid(clp, stateid);
+	if (inode == ERR_PTR(-ENOENT))
+		inode = nfs_layout_find_inode_by_fh(clp, fh);
+	rcu_read_unlock();
+	spin_unlock(&clp->cl_lock);
+
+	return inode;
+}
+
+/*
+ * Enforce RFC5661 section 12.5.5.2.1. (Layout Recall and Return Sequencing)
+ */
+static u32 pnfs_check_callback_stateid(struct pnfs_layout_hdr *lo,
+					const nfs4_stateid *new)
+{
+	u32 oldseq, newseq;
+
+	/* Is the stateid not initialised? */
+	if (!pnfs_layout_is_valid(lo))
+		return NFS4ERR_NOMATCHING_LAYOUT;
+
+	/* Mismatched stateid? */
+	if (!nfs4_stateid_match_other(&lo->plh_stateid, new))
+		return NFS4ERR_BAD_STATEID;
+
+	newseq = be32_to_cpu(new->seqid);
+	/* Are we already in a layout recall situation? */
+	if (test_bit(NFS_LAYOUT_RETURN_REQUESTED, &lo->plh_flags) &&
+	    lo->plh_return_seq != 0) {
+		if (newseq < lo->plh_return_seq)
+			return NFS4ERR_OLD_STATEID;
+		if (newseq > lo->plh_return_seq)
+			return NFS4ERR_DELAY;
+		goto out;
+	}
+
+	/* Check that the stateid matches what we think it should be. */
+	oldseq = be32_to_cpu(lo->plh_stateid.seqid);
+	if (newseq > oldseq + 1)
+		return NFS4ERR_DELAY;
+	/* Crazy server! */
+	if (newseq <= oldseq)
+		return NFS4ERR_OLD_STATEID;
+out:
+	return NFS_OK;
+}
+
+static u32 initiate_file_draining(struct nfs_client *clp,
+				  struct cb_layoutrecallargs *args)
+{
+	struct inode *ino;
+	struct pnfs_layout_hdr *lo;
+	u32 rv = NFS4ERR_NOMATCHING_LAYOUT;
+	LIST_HEAD(free_me_list);
+
+	ino = nfs_layout_find_inode(clp, &args->cbl_fh, &args->cbl_stateid);
+	if (IS_ERR(ino)) {
+		if (ino == ERR_PTR(-EAGAIN))
+			rv = NFS4ERR_DELAY;
+		goto out_noput;
+	}
+
+	pnfs_layoutcommit_inode(ino, false);
+
+
+	spin_lock(&ino->i_lock);
+	lo = NFS_I(ino)->layout;
+	if (!lo) {
+		spin_unlock(&ino->i_lock);
+		goto out;
+	}
+	pnfs_get_layout_hdr(lo);
+	rv = pnfs_check_callback_stateid(lo, &args->cbl_stateid);
+	if (rv != NFS_OK)
+		goto unlock;
+
+	/*
+	 * Enforce RFC5661 Section 12.5.5.2.1.5 (Bulk Recall and Return)
+	 */
+	if (test_bit(NFS_LAYOUT_BULK_RECALL, &lo->plh_flags)) {
+		rv = NFS4ERR_DELAY;
+		goto unlock;
+	}
+
+	pnfs_set_layout_stateid(lo, &args->cbl_stateid, true);
+	switch (pnfs_mark_matching_lsegs_return(lo, &free_me_list,
+				&args->cbl_range,
+				be32_to_cpu(args->cbl_stateid.seqid))) {
+	case 0:
+	case -EBUSY:
+		/* There are layout segments that need to be returned */
+		rv = NFS4_OK;
+		break;
+	case -ENOENT:
+		/* Embrace your forgetfulness! */
+		rv = NFS4ERR_NOMATCHING_LAYOUT;
+
+		if (NFS_SERVER(ino)->pnfs_curr_ld->return_range) {
+			NFS_SERVER(ino)->pnfs_curr_ld->return_range(lo,
+				&args->cbl_range);
+		}
+	}
+unlock:
+	spin_unlock(&ino->i_lock);
+	pnfs_free_lseg_list(&free_me_list);
+	/* Free all lsegs that are attached to commit buckets */
+	nfs_commit_inode(ino, 0);
+	pnfs_put_layout_hdr(lo);
+out:
+	nfs_iput_and_deactive(ino);
+out_noput:
+	trace_nfs4_cb_layoutrecall_file(clp, &args->cbl_fh, ino,
+			&args->cbl_stateid, -rv);
+	return rv;
+}
+
+static u32 initiate_bulk_draining(struct nfs_client *clp,
+				  struct cb_layoutrecallargs *args)
+{
+	int stat;
+
+	if (args->cbl_recall_type == RETURN_FSID)
+		stat = pnfs_destroy_layouts_byfsid(clp, &args->cbl_fsid, true);
+	else
+		stat = pnfs_destroy_layouts_byclid(clp, true);
+	if (stat != 0)
+		return NFS4ERR_DELAY;
+	return NFS4ERR_NOMATCHING_LAYOUT;
+}
+
+static u32 do_callback_layoutrecall(struct nfs_client *clp,
+				    struct cb_layoutrecallargs *args)
+{
+	if (args->cbl_recall_type == RETURN_FILE)
+		return initiate_file_draining(clp, args);
+	return initiate_bulk_draining(clp, args);
+}
+
+__be32 nfs4_callback_layoutrecall(void *argp, void *resp,
+				  struct cb_process_state *cps)
+{
+	struct cb_layoutrecallargs *args = argp;
+	u32 res = NFS4ERR_OP_NOT_IN_SESSION;
+
+	if (cps->clp)
+		res = do_callback_layoutrecall(cps->clp, args);
+	return cpu_to_be32(res);
+}
+
+static void pnfs_recall_all_layouts(struct nfs_client *clp)
+{
+	struct cb_layoutrecallargs args;
+
+	/* Pretend we got a CB_LAYOUTRECALL(ALL) */
+	memset(&args, 0, sizeof(args));
+	args.cbl_recall_type = RETURN_ALL;
+	/* FIXME we ignore errors, what should we do? */
+	do_callback_layoutrecall(clp, &args);
+}
+
+__be32 nfs4_callback_devicenotify(void *argp, void *resp,
+				  struct cb_process_state *cps)
+{
+	struct cb_devicenotifyargs *args = argp;
+	int i;
+	__be32 res = 0;
+	struct nfs_client *clp = cps->clp;
+	struct nfs_server *server = NULL;
+
+	if (!clp) {
+		res = cpu_to_be32(NFS4ERR_OP_NOT_IN_SESSION);
+		goto out;
+	}
+
+	for (i = 0; i < args->ndevs; i++) {
+		struct cb_devicenotifyitem *dev = &args->devs[i];
+
+		if (!server ||
+		    server->pnfs_curr_ld->id != dev->cbd_layout_type) {
+			rcu_read_lock();
+			list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
+				if (server->pnfs_curr_ld &&
+				    server->pnfs_curr_ld->id == dev->cbd_layout_type) {
+					rcu_read_unlock();
+					goto found;
+				}
+			rcu_read_unlock();
+			continue;
+		}
+
+	found:
+		nfs4_delete_deviceid(server->pnfs_curr_ld, clp, &dev->cbd_dev_id);
+	}
+
+out:
+	kfree(args->devs);
+	return res;
+}
+
+/*
+ * Validate the sequenceID sent by the server.
+ * Return success if the sequenceID is one more than what we last saw on
+ * this slot, accounting for wraparound.  Increments the slot's sequence.
+ *
+ * We don't yet implement a duplicate request cache, instead we set the
+ * back channel ca_maxresponsesize_cached to zero. This is OK for now
+ * since we only currently implement idempotent callbacks anyway.
+ *
+ * We have a single slot backchannel at this time, so we don't bother
+ * checking the used_slots bit array on the table.  The lower layer guarantees
+ * a single outstanding callback request at a time.
+ */
+static __be32
+validate_seqid(const struct nfs4_slot_table *tbl, const struct nfs4_slot *slot,
+		const struct cb_sequenceargs * args)
+{
+	__be32 ret;
+
+	ret = cpu_to_be32(NFS4ERR_BADSLOT);
+	if (args->csa_slotid > tbl->server_highest_slotid)
+		goto out_err;
+
+	/* Replay */
+	if (args->csa_sequenceid == slot->seq_nr) {
+		ret = cpu_to_be32(NFS4ERR_DELAY);
+		if (nfs4_test_locked_slot(tbl, slot->slot_nr))
+			goto out_err;
+
+		/* Signal process_op to set this error on next op */
+		ret = cpu_to_be32(NFS4ERR_RETRY_UNCACHED_REP);
+		if (args->csa_cachethis == 0)
+			goto out_err;
+
+		/* Liar! We never allowed you to set csa_cachethis != 0 */
+		ret = cpu_to_be32(NFS4ERR_SEQ_FALSE_RETRY);
+		goto out_err;
+	}
+
+	/* Note: wraparound relies on seq_nr being of type u32 */
+	/* Misordered request */
+	ret = cpu_to_be32(NFS4ERR_SEQ_MISORDERED);
+	if (args->csa_sequenceid != slot->seq_nr + 1)
+		goto out_err;
+
+	return cpu_to_be32(NFS4_OK);
+
+out_err:
+	trace_nfs4_cb_seqid_err(args, ret);
+	return ret;
+}
+
+/*
+ * For each referring call triple, check the session's slot table for
+ * a match.  If the slot is in use and the sequence numbers match, the
+ * client is still waiting for a response to the original request.
+ */
+static int referring_call_exists(struct nfs_client *clp,
+				  uint32_t nrclists,
+				  struct referring_call_list *rclists,
+				  spinlock_t *lock)
+	__releases(lock)
+	__acquires(lock)
+{
+	int status = 0;
+	int i, j;
+	struct nfs4_session *session;
+	struct nfs4_slot_table *tbl;
+	struct referring_call_list *rclist;
+	struct referring_call *ref;
+
+	/*
+	 * XXX When client trunking is implemented, this becomes
+	 * a session lookup from within the loop
+	 */
+	session = clp->cl_session;
+	tbl = &session->fc_slot_table;
+
+	for (i = 0; i < nrclists; i++) {
+		rclist = &rclists[i];
+		if (memcmp(session->sess_id.data,
+			   rclist->rcl_sessionid.data,
+			   NFS4_MAX_SESSIONID_LEN) != 0)
+			continue;
+
+		for (j = 0; j < rclist->rcl_nrefcalls; j++) {
+			ref = &rclist->rcl_refcalls[j];
+			spin_unlock(lock);
+			status = nfs4_slot_wait_on_seqid(tbl, ref->rc_slotid,
+					ref->rc_sequenceid, HZ >> 1) < 0;
+			spin_lock(lock);
+			if (status)
+				goto out;
+		}
+	}
+
+out:
+	return status;
+}
+
+__be32 nfs4_callback_sequence(void *argp, void *resp,
+			      struct cb_process_state *cps)
+{
+	struct cb_sequenceargs *args = argp;
+	struct cb_sequenceres *res = resp;
+	struct nfs4_slot_table *tbl;
+	struct nfs4_slot *slot;
+	struct nfs_client *clp;
+	int i;
+	__be32 status = htonl(NFS4ERR_BADSESSION);
+
+	clp = nfs4_find_client_sessionid(cps->net, args->csa_addr,
+					 &args->csa_sessionid, cps->minorversion);
+	if (clp == NULL)
+		goto out;
+
+	if (!(clp->cl_session->flags & SESSION4_BACK_CHAN))
+		goto out;
+
+	tbl = &clp->cl_session->bc_slot_table;
+
+	/* Set up res before grabbing the spinlock */
+	memcpy(&res->csr_sessionid, &args->csa_sessionid,
+	       sizeof(res->csr_sessionid));
+	res->csr_sequenceid = args->csa_sequenceid;
+	res->csr_slotid = args->csa_slotid;
+
+	spin_lock(&tbl->slot_tbl_lock);
+	/* state manager is resetting the session */
+	if (test_bit(NFS4_SLOT_TBL_DRAINING, &tbl->slot_tbl_state)) {
+		status = htonl(NFS4ERR_DELAY);
+		/* Return NFS4ERR_BADSESSION if we're draining the session
+		 * in order to reset it.
+		 */
+		if (test_bit(NFS4CLNT_SESSION_RESET, &clp->cl_state))
+			status = htonl(NFS4ERR_BADSESSION);
+		goto out_unlock;
+	}
+
+	status = htonl(NFS4ERR_BADSLOT);
+	slot = nfs4_lookup_slot(tbl, args->csa_slotid);
+	if (IS_ERR(slot))
+		goto out_unlock;
+
+	res->csr_highestslotid = tbl->server_highest_slotid;
+	res->csr_target_highestslotid = tbl->target_highest_slotid;
+
+	status = validate_seqid(tbl, slot, args);
+	if (status)
+		goto out_unlock;
+	if (!nfs4_try_to_lock_slot(tbl, slot)) {
+		status = htonl(NFS4ERR_DELAY);
+		goto out_unlock;
+	}
+	cps->slot = slot;
+
+	/* The ca_maxresponsesize_cached is 0 with no DRC */
+	if (args->csa_cachethis != 0) {
+		status = htonl(NFS4ERR_REP_TOO_BIG_TO_CACHE);
+		goto out_unlock;
+	}
+
+	/*
+	 * Check for pending referring calls.  If a match is found, a
+	 * related callback was received before the response to the original
+	 * call.
+	 */
+	if (referring_call_exists(clp, args->csa_nrclists, args->csa_rclists,
+				&tbl->slot_tbl_lock) < 0) {
+		status = htonl(NFS4ERR_DELAY);
+		goto out_unlock;
+	}
+
+	/*
+	 * RFC5661 20.9.3
+	 * If CB_SEQUENCE returns an error, then the state of the slot
+	 * (sequence ID, cached reply) MUST NOT change.
+	 */
+	slot->seq_nr = args->csa_sequenceid;
+out_unlock:
+	spin_unlock(&tbl->slot_tbl_lock);
+
+out:
+	cps->clp = clp; /* put in nfs4_callback_compound */
+	for (i = 0; i < args->csa_nrclists; i++)
+		kfree(args->csa_rclists[i].rcl_refcalls);
+	kfree(args->csa_rclists);
+
+	if (status == htonl(NFS4ERR_RETRY_UNCACHED_REP)) {
+		cps->drc_status = status;
+		status = 0;
+	} else
+		res->csr_status = status;
+
+	trace_nfs4_cb_sequence(args, res, status);
+	return status;
+}
+
+static bool
+validate_bitmap_values(unsigned int mask)
+{
+	return (mask & ~RCA4_TYPE_MASK_ALL) == 0;
+}
+
+__be32 nfs4_callback_recallany(void *argp, void *resp,
+			       struct cb_process_state *cps)
+{
+	struct cb_recallanyargs *args = argp;
+	__be32 status;
+	fmode_t flags = 0;
+
+	status = cpu_to_be32(NFS4ERR_OP_NOT_IN_SESSION);
+	if (!cps->clp) /* set in cb_sequence */
+		goto out;
+
+	dprintk_rcu("NFS: RECALL_ANY callback request from %s\n",
+		rpc_peeraddr2str(cps->clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+
+	status = cpu_to_be32(NFS4ERR_INVAL);
+	if (!validate_bitmap_values(args->craa_type_mask))
+		goto out;
+
+	status = cpu_to_be32(NFS4_OK);
+	if (args->craa_type_mask & BIT(RCA4_TYPE_MASK_RDATA_DLG))
+		flags = FMODE_READ;
+	if (args->craa_type_mask & BIT(RCA4_TYPE_MASK_WDATA_DLG))
+		flags |= FMODE_WRITE;
+	if (flags)
+		nfs_expire_unused_delegation_types(cps->clp, flags);
+
+	if (args->craa_type_mask & BIT(RCA4_TYPE_MASK_FILE_LAYOUT))
+		pnfs_recall_all_layouts(cps->clp);
+out:
+	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
+	return status;
+}
+
+/* Reduce the fore channel's max_slots to the target value */
+__be32 nfs4_callback_recallslot(void *argp, void *resp,
+				struct cb_process_state *cps)
+{
+	struct cb_recallslotargs *args = argp;
+	struct nfs4_slot_table *fc_tbl;
+	__be32 status;
+
+	status = htonl(NFS4ERR_OP_NOT_IN_SESSION);
+	if (!cps->clp) /* set in cb_sequence */
+		goto out;
+
+	dprintk_rcu("NFS: CB_RECALL_SLOT request from %s target highest slotid %u\n",
+		rpc_peeraddr2str(cps->clp->cl_rpcclient, RPC_DISPLAY_ADDR),
+		args->crsa_target_highest_slotid);
+
+	fc_tbl = &cps->clp->cl_session->fc_slot_table;
+
+	status = htonl(NFS4_OK);
+
+	nfs41_set_target_slotid(fc_tbl, args->crsa_target_highest_slotid);
+	nfs41_notify_server(cps->clp);
+out:
+	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
+	return status;
+}
+
+__be32 nfs4_callback_notify_lock(void *argp, void *resp,
+				 struct cb_process_state *cps)
+{
+	struct cb_notify_lock_args *args = argp;
+
+	if (!cps->clp) /* set in cb_sequence */
+		return htonl(NFS4ERR_OP_NOT_IN_SESSION);
+
+	dprintk_rcu("NFS: CB_NOTIFY_LOCK request from %s\n",
+		rpc_peeraddr2str(cps->clp->cl_rpcclient, RPC_DISPLAY_ADDR));
+
+	/* Don't wake anybody if the string looked bogus */
+	if (args->cbnl_valid)
+		__wake_up(&cps->clp->cl_lock_waitq, TASK_NORMAL, 0, args);
+
+	return htonl(NFS4_OK);
+}
+#endif /* CONFIG_NFS_V4_1 */
+#ifdef CONFIG_NFS_V4_2
+static void nfs4_copy_cb_args(struct nfs4_copy_state *cp_state,
+				struct cb_offloadargs *args)
+{
+	cp_state->count = args->wr_count;
+	cp_state->error = args->error;
+	if (!args->error) {
+		cp_state->verf.committed = args->wr_writeverf.committed;
+		memcpy(&cp_state->verf.verifier.data[0],
+			&args->wr_writeverf.verifier.data[0],
+			NFS4_VERIFIER_SIZE);
+	}
+}
+
+__be32 nfs4_callback_offload(void *data, void *dummy,
+			     struct cb_process_state *cps)
+{
+	struct cb_offloadargs *args = data;
+	struct nfs_server *server;
+	struct nfs4_copy_state *copy, *tmp_copy;
+	bool found = false;
+
+	copy = kzalloc(sizeof(struct nfs4_copy_state), GFP_NOFS);
+	if (!copy)
+		return htonl(NFS4ERR_SERVERFAULT);
+
+	spin_lock(&cps->clp->cl_lock);
+	rcu_read_lock();
+	list_for_each_entry_rcu(server, &cps->clp->cl_superblocks,
+				client_link) {
+		list_for_each_entry(tmp_copy, &server->ss_copies, copies) {
+			if (memcmp(args->coa_stateid.other,
+					tmp_copy->stateid.other,
+					sizeof(args->coa_stateid.other)))
+				continue;
+			nfs4_copy_cb_args(tmp_copy, args);
+			complete(&tmp_copy->completion);
+			found = true;
+			goto out;
+		}
+	}
+out:
+	rcu_read_unlock();
+	if (!found) {
+		memcpy(&copy->stateid, &args->coa_stateid, NFS4_STATEID_SIZE);
+		nfs4_copy_cb_args(copy, args);
+		list_add_tail(&copy->copies, &cps->clp->pending_cb_stateids);
+	} else
+		kfree(copy);
+	spin_unlock(&cps->clp->cl_lock);
+
+	return 0;
+}
+#endif /* CONFIG_NFS_V4_2 */