fs/dlm/rcom.c - kernel/msm-4.9 - Gitiles

 /******************************************************************************
 *******************************************************************************
 **
 **  Copyright (C) Sistina Software, Inc.  1997-2003  All rights reserved.
 **  Copyright (C) 2005-2008 Red Hat, Inc.  All rights reserved.
 **
 **  This copyrighted material is made available to anyone wishing to use,
 **  modify, copy, or redistribute it subject to the terms and conditions
 **  of the GNU General Public License v.2.
 **
 *******************************************************************************
 ******************************************************************************/

 #include "dlm_internal.h"
 #include "lockspace.h"
 #include "member.h"
 #include "lowcomms.h"
 #include "midcomms.h"
 #include "rcom.h"
 #include "recover.h"
 #include "dir.h"
 #include "config.h"
 #include "memory.h"
 #include "lock.h"
 #include "util.h"

 static int rcom_response(struct dlm_ls *ls)
 {
 	return test_bit(LSFL_RCOM_READY, &ls->ls_flags);
 }

 static int create_rcom(struct dlm_ls *ls, int to_nodeid, int type, int len,
 		       struct dlm_rcom **rc_ret, struct dlm_mhandle **mh_ret)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	char *mb;
 	int mb_len = sizeof(struct dlm_rcom) + len;

 	mh = dlm_lowcomms_get_buffer(to_nodeid, mb_len, GFP_NOFS, &mb);
 	if (!mh) {
 		log_print("create_rcom to %d type %d len %d ENOBUFS",
 			  to_nodeid, type, len);
 		return -ENOBUFS;
 	}
 	memset(mb, 0, mb_len);

 	rc = (struct dlm_rcom *) mb;

 	rc->rc_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
 	rc->rc_header.h_lockspace = ls->ls_global_id;
 	rc->rc_header.h_nodeid = dlm_our_nodeid();
 	rc->rc_header.h_length = mb_len;
 	rc->rc_header.h_cmd = DLM_RCOM;

 	rc->rc_type = type;

 	spin_lock(&ls->ls_recover_lock);
 	rc->rc_seq = ls->ls_recover_seq;
 	spin_unlock(&ls->ls_recover_lock);

 	*mh_ret = mh;
 	*rc_ret = rc;
 	return 0;
 }

 static void send_rcom(struct dlm_ls *ls, struct dlm_mhandle *mh,
 		      struct dlm_rcom *rc)
 {
 	dlm_rcom_out(rc);
 	dlm_lowcomms_commit_buffer(mh);
 }

 static void set_rcom_status(struct dlm_ls *ls, struct rcom_status *rs,
 			    uint32_t flags)
 {
 	rs->rs_flags = cpu_to_le32(flags);
 }

 /* When replying to a status request, a node also sends back its
    configuration values.  The requesting node then checks that the remote
    node is configured the same way as itself. */

 static void set_rcom_config(struct dlm_ls *ls, struct rcom_config *rf,
 			    uint32_t num_slots)
 {
 	rf->rf_lvblen = cpu_to_le32(ls->ls_lvblen);
 	rf->rf_lsflags = cpu_to_le32(ls->ls_exflags);

 	rf->rf_our_slot = cpu_to_le16(ls->ls_slot);
 	rf->rf_num_slots = cpu_to_le16(num_slots);
 	rf->rf_generation =  cpu_to_le32(ls->ls_generation);
 }

 static int check_rcom_config(struct dlm_ls *ls, struct dlm_rcom *rc, int nodeid)
 {
 	struct rcom_config *rf = (struct rcom_config *) rc->rc_buf;

 	if ((rc->rc_header.h_version & 0xFFFF0000) != DLM_HEADER_MAJOR) {
 		log_error(ls, "version mismatch: %x nodeid %d: %x",
 			  DLM_HEADER_MAJOR | DLM_HEADER_MINOR, nodeid,
 			  rc->rc_header.h_version);
 		return -EPROTO;
 	}

 	if (le32_to_cpu(rf->rf_lvblen) != ls->ls_lvblen ||
 	    le32_to_cpu(rf->rf_lsflags) != ls->ls_exflags) {
 		log_error(ls, "config mismatch: %d,%x nodeid %d: %d,%x",
 			  ls->ls_lvblen, ls->ls_exflags, nodeid,
 			  le32_to_cpu(rf->rf_lvblen),
 			  le32_to_cpu(rf->rf_lsflags));
 		return -EPROTO;
 	}
 	return 0;
 }

 static void allow_sync_reply(struct dlm_ls *ls, uint64_t *new_seq)
 {
 	spin_lock(&ls->ls_rcom_spin);
 	*new_seq = ++ls->ls_rcom_seq;
 	set_bit(LSFL_RCOM_WAIT, &ls->ls_flags);
 	spin_unlock(&ls->ls_rcom_spin);
 }

 static void disallow_sync_reply(struct dlm_ls *ls)
 {
 	spin_lock(&ls->ls_rcom_spin);
 	clear_bit(LSFL_RCOM_WAIT, &ls->ls_flags);
 	clear_bit(LSFL_RCOM_READY, &ls->ls_flags);
 	spin_unlock(&ls->ls_rcom_spin);
 }

 /*
  * low nodeid gathers one slot value at a time from each node.
  * it sets need_slots=0, and saves rf_our_slot returned from each
  * rcom_config.
  *
  * other nodes gather all slot values at once from the low nodeid.
  * they set need_slots=1, and ignore the rf_our_slot returned from each
  * rcom_config.  they use the rf_num_slots returned from the low
  * node's rcom_config.
  */

 int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	int error = 0;

 	ls->ls_recover_nodeid = nodeid;

 	if (nodeid == dlm_our_nodeid()) {
 		rc = ls->ls_recover_buf;
 		rc->rc_result = dlm_recover_status(ls);
 		goto out;
 	}

 	error = create_rcom(ls, nodeid, DLM_RCOM_STATUS,
 			    sizeof(struct rcom_status), &rc, &mh);
 	if (error)
 		goto out;

 	set_rcom_status(ls, (struct rcom_status *)rc->rc_buf, status_flags);

 	allow_sync_reply(ls, &rc->rc_id);
 	memset(ls->ls_recover_buf, 0, dlm_config.ci_buffer_size);

 	send_rcom(ls, mh, rc);

 	error = dlm_wait_function(ls, &rcom_response);
 	disallow_sync_reply(ls);
 	if (error)
 		goto out;

 	rc = ls->ls_recover_buf;

 	if (rc->rc_result == -ESRCH) {
 		/* we pretend the remote lockspace exists with 0 status */
 		log_debug(ls, "remote node %d not ready", nodeid);
 		rc->rc_result = 0;
 		error = 0;
 	} else {
 		error = check_rcom_config(ls, rc, nodeid);
 	}

 	/* the caller looks at rc_result for the remote recovery status */
  out:
 	return error;
 }

 static void receive_rcom_status(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	struct rcom_status *rs;
 	uint32_t status;
 	int nodeid = rc_in->rc_header.h_nodeid;
 	int len = sizeof(struct rcom_config);
 	int num_slots = 0;
 	int error;

 	if (!dlm_slots_version(&rc_in->rc_header)) {
 		status = dlm_recover_status(ls);
 		goto do_create;
 	}

 	rs = (struct rcom_status *)rc_in->rc_buf;

 	if (!(rs->rs_flags & DLM_RSF_NEED_SLOTS)) {
 		status = dlm_recover_status(ls);
 		goto do_create;
 	}

 	spin_lock(&ls->ls_recover_lock);
 	status = ls->ls_recover_status;
 	num_slots = ls->ls_num_slots;
 	spin_unlock(&ls->ls_recover_lock);
 	len += num_slots * sizeof(struct rcom_slot);

  do_create:
 	error = create_rcom(ls, nodeid, DLM_RCOM_STATUS_REPLY,
 			    len, &rc, &mh);
 	if (error)
 		return;

 	rc->rc_id = rc_in->rc_id;
 	rc->rc_seq_reply = rc_in->rc_seq;
 	rc->rc_result = status;

 	set_rcom_config(ls, (struct rcom_config *)rc->rc_buf, num_slots);

 	if (!num_slots)
 		goto do_send;

 	spin_lock(&ls->ls_recover_lock);
 	if (ls->ls_num_slots != num_slots) {
 		spin_unlock(&ls->ls_recover_lock);
 		log_debug(ls, "receive_rcom_status num_slots %d to %d",
 			  num_slots, ls->ls_num_slots);
 		rc->rc_result = 0;
 		set_rcom_config(ls, (struct rcom_config *)rc->rc_buf, 0);
 		goto do_send;
 	}

 	dlm_slots_copy_out(ls, rc);
 	spin_unlock(&ls->ls_recover_lock);

  do_send:
 	send_rcom(ls, mh, rc);
 }

 static void receive_sync_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
 	spin_lock(&ls->ls_rcom_spin);
 	if (!test_bit(LSFL_RCOM_WAIT, &ls->ls_flags) ||
 	    rc_in->rc_id != ls->ls_rcom_seq) {
 		log_debug(ls, "reject reply %d from %d seq %llx expect %llx",
 			  rc_in->rc_type, rc_in->rc_header.h_nodeid,
 			  (unsigned long long)rc_in->rc_id,
 			  (unsigned long long)ls->ls_rcom_seq);
 		goto out;
 	}
 	memcpy(ls->ls_recover_buf, rc_in, rc_in->rc_header.h_length);
 	set_bit(LSFL_RCOM_READY, &ls->ls_flags);
 	clear_bit(LSFL_RCOM_WAIT, &ls->ls_flags);
 	wake_up(&ls->ls_wait_general);
  out:
 	spin_unlock(&ls->ls_rcom_spin);
 }

 int dlm_rcom_names(struct dlm_ls *ls, int nodeid, char *last_name, int last_len)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	int error = 0;

 	ls->ls_recover_nodeid = nodeid;

 	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES, last_len, &rc, &mh);
 	if (error)
 		goto out;
 	memcpy(rc->rc_buf, last_name, last_len);

 	allow_sync_reply(ls, &rc->rc_id);
 	memset(ls->ls_recover_buf, 0, dlm_config.ci_buffer_size);

 	send_rcom(ls, mh, rc);

 	error = dlm_wait_function(ls, &rcom_response);
 	disallow_sync_reply(ls);
  out:
 	return error;
 }

 static void receive_rcom_names(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	int error, inlen, outlen, nodeid;

 	nodeid = rc_in->rc_header.h_nodeid;
 	inlen = rc_in->rc_header.h_length - sizeof(struct dlm_rcom);
 	outlen = dlm_config.ci_buffer_size - sizeof(struct dlm_rcom);

 	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES_REPLY, outlen, &rc, &mh);
 	if (error)
 		return;
 	rc->rc_id = rc_in->rc_id;
 	rc->rc_seq_reply = rc_in->rc_seq;

 	dlm_copy_master_names(ls, rc_in->rc_buf, inlen, rc->rc_buf, outlen,
 			      nodeid);
 	send_rcom(ls, mh, rc);
 }

 int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	struct dlm_ls *ls = r->res_ls;
 	int error;

 	error = create_rcom(ls, dir_nodeid, DLM_RCOM_LOOKUP, r->res_length,
 			    &rc, &mh);
 	if (error)
 		goto out;
 	memcpy(rc->rc_buf, r->res_name, r->res_length);
 	rc->rc_id = (unsigned long) r->res_id;

 	send_rcom(ls, mh, rc);
  out:
 	return error;
 }

 int dlm_send_rcom_lookup_dump(struct dlm_rsb *r, int to_nodeid)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	struct dlm_ls *ls = r->res_ls;
 	int error;

 	error = create_rcom(ls, to_nodeid, DLM_RCOM_LOOKUP, r->res_length,
 			    &rc, &mh);
 	if (error)
 		goto out;
 	memcpy(rc->rc_buf, r->res_name, r->res_length);
 	rc->rc_id = 0xFFFFFFFF;

 	send_rcom(ls, mh, rc);
  out:
 	return error;
 }

 static void receive_rcom_lookup(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	int error, ret_nodeid, nodeid = rc_in->rc_header.h_nodeid;
 	int len = rc_in->rc_header.h_length - sizeof(struct dlm_rcom);

 	error = create_rcom(ls, nodeid, DLM_RCOM_LOOKUP_REPLY, 0, &rc, &mh);
 	if (error)
 		return;

 	if (rc_in->rc_id == 0xFFFFFFFF) {
 		log_error(ls, "receive_rcom_lookup dump from %d", nodeid);
 		dlm_dump_rsb_name(ls, rc_in->rc_buf, len);
 		return;
 	}

 	error = dlm_master_lookup(ls, nodeid, rc_in->rc_buf, len,
 				  DLM_LU_RECOVER_MASTER, &ret_nodeid, NULL);
 	if (error)
 		ret_nodeid = error;
 	rc->rc_result = ret_nodeid;
 	rc->rc_id = rc_in->rc_id;
 	rc->rc_seq_reply = rc_in->rc_seq;

 	send_rcom(ls, mh, rc);
 }

 static void receive_rcom_lookup_reply(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
 	dlm_recover_master_reply(ls, rc_in);
 }

 static void pack_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb,
 			   struct rcom_lock *rl)
 {
 	memset(rl, 0, sizeof(*rl));

 	rl->rl_ownpid = cpu_to_le32(lkb->lkb_ownpid);
 	rl->rl_lkid = cpu_to_le32(lkb->lkb_id);
 	rl->rl_exflags = cpu_to_le32(lkb->lkb_exflags);
 	rl->rl_flags = cpu_to_le32(lkb->lkb_flags);
 	rl->rl_lvbseq = cpu_to_le32(lkb->lkb_lvbseq);
 	rl->rl_rqmode = lkb->lkb_rqmode;
 	rl->rl_grmode = lkb->lkb_grmode;
 	rl->rl_status = lkb->lkb_status;
 	rl->rl_wait_type = cpu_to_le16(lkb->lkb_wait_type);

 	if (lkb->lkb_bastfn)
 		rl->rl_asts |= DLM_CB_BAST;
 	if (lkb->lkb_astfn)
 		rl->rl_asts |= DLM_CB_CAST;

 	rl->rl_namelen = cpu_to_le16(r->res_length);
 	memcpy(rl->rl_name, r->res_name, r->res_length);

 	/* FIXME: might we have an lvb without DLM_LKF_VALBLK set ?
 	   If so, receive_rcom_lock_args() won't take this copy. */

 	if (lkb->lkb_lvbptr)
 		memcpy(rl->rl_lvb, lkb->lkb_lvbptr, r->res_ls->ls_lvblen);
 }

 int dlm_send_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 {
 	struct dlm_ls *ls = r->res_ls;
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	struct rcom_lock *rl;
 	int error, len = sizeof(struct rcom_lock);

 	if (lkb->lkb_lvbptr)
 		len += ls->ls_lvblen;

 	error = create_rcom(ls, r->res_nodeid, DLM_RCOM_LOCK, len, &rc, &mh);
 	if (error)
 		goto out;

 	rl = (struct rcom_lock *) rc->rc_buf;
 	pack_rcom_lock(r, lkb, rl);
 	rc->rc_id = (unsigned long) r;

 	send_rcom(ls, mh, rc);
  out:
 	return error;
 }

 /* needs at least dlm_rcom + rcom_lock */
 static void receive_rcom_lock(struct dlm_ls *ls, struct dlm_rcom *rc_in)
 {
 	struct dlm_rcom *rc;
 	struct dlm_mhandle *mh;
 	int error, nodeid = rc_in->rc_header.h_nodeid;

 	dlm_recover_master_copy(ls, rc_in);

 	error = create_rcom(ls, nodeid, DLM_RCOM_LOCK_REPLY,
 			    sizeof(struct rcom_lock), &rc, &mh);
 	if (error)
 		return;

 	/* We send back the same rcom_lock struct we received, but
 	   dlm_recover_master_copy() has filled in rl_remid and rl_result */

 	memcpy(rc->rc_buf, rc_in->rc_buf, sizeof(struct rcom_lock));
 	rc->rc_id = rc_in->rc_id;
 	rc->rc_seq_reply = rc_in->rc_seq;

 	send_rcom(ls, mh, rc);
 }

 /* If the lockspace doesn't exist then still send a status message
    back; it's possible that it just doesn't have its global_id yet. */

 int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
 {
 	struct dlm_rcom *rc;
 	struct rcom_config *rf;
 	struct dlm_mhandle *mh;
 	char *mb;
 	int mb_len = sizeof(struct dlm_rcom) + sizeof(struct rcom_config);

 	mh = dlm_lowcomms_get_buffer(nodeid, mb_len, GFP_NOFS, &mb);
 	if (!mh)
 		return -ENOBUFS;
 	memset(mb, 0, mb_len);

 	rc = (struct dlm_rcom *) mb;

 	rc->rc_header.h_version = (DLM_HEADER_MAJOR | DLM_HEADER_MINOR);
 	rc->rc_header.h_lockspace = rc_in->rc_header.h_lockspace;
 	rc->rc_header.h_nodeid = dlm_our_nodeid();
 	rc->rc_header.h_length = mb_len;
 	rc->rc_header.h_cmd = DLM_RCOM;

 	rc->rc_type = DLM_RCOM_STATUS_REPLY;
 	rc->rc_id = rc_in->rc_id;
 	rc->rc_seq_reply = rc_in->rc_seq;
 	rc->rc_result = -ESRCH;

 	rf = (struct rcom_config *) rc->rc_buf;
 	rf->rf_lvblen = cpu_to_le32(~0U);

 	dlm_rcom_out(rc);
 	dlm_lowcomms_commit_buffer(mh);

 	return 0;
 }

 /*
  * Ignore messages for stage Y before we set
  * recover_status bit for stage X:
  *
  * recover_status = 0
  *
  * dlm_recover_members()
  * - send nothing
  * - recv nothing
  * - ignore NAMES, NAMES_REPLY
  * - ignore LOOKUP, LOOKUP_REPLY
  * - ignore LOCK, LOCK_REPLY
  *
  * recover_status |= NODES
  *
  * dlm_recover_members_wait()
  *
  * dlm_recover_directory()
  * - send NAMES
  * - recv NAMES_REPLY
  * - ignore LOOKUP, LOOKUP_REPLY
  * - ignore LOCK, LOCK_REPLY
  *
  * recover_status |= DIR
  *
  * dlm_recover_directory_wait()
  *
  * dlm_recover_masters()
  * - send LOOKUP
  * - recv LOOKUP_REPLY
  *
  * dlm_recover_locks()
  * - send LOCKS
  * - recv LOCKS_REPLY
  *
  * recover_status |= LOCKS
  *
  * dlm_recover_locks_wait()
  *
  * recover_status |= DONE
  */

 /* Called by dlm_recv; corresponds to dlm_receive_message() but special
    recovery-only comms are sent through here. */

 void dlm_receive_rcom(struct dlm_ls *ls, struct dlm_rcom *rc, int nodeid)
 {
 	int lock_size = sizeof(struct dlm_rcom) + sizeof(struct rcom_lock);
 	int stop, reply = 0, names = 0, lookup = 0, lock = 0;
 	uint32_t status;
 	uint64_t seq;

 	switch (rc->rc_type) {
 	case DLM_RCOM_STATUS_REPLY:
 		reply = 1;
 		break;
 	case DLM_RCOM_NAMES:
 		names = 1;
 		break;
 	case DLM_RCOM_NAMES_REPLY:
 		names = 1;
 		reply = 1;
 		break;
 	case DLM_RCOM_LOOKUP:
 		lookup = 1;
 		break;
 	case DLM_RCOM_LOOKUP_REPLY:
 		lookup = 1;
 		reply = 1;
 		break;
 	case DLM_RCOM_LOCK:
 		lock = 1;
 		break;
 	case DLM_RCOM_LOCK_REPLY:
 		lock = 1;
 		reply = 1;
 		break;
 	};

 	spin_lock(&ls->ls_recover_lock);
 	status = ls->ls_recover_status;
 	stop = test_bit(LSFL_RECOVER_STOP, &ls->ls_flags);
 	seq = ls->ls_recover_seq;
 	spin_unlock(&ls->ls_recover_lock);

 	if (stop && (rc->rc_type != DLM_RCOM_STATUS))
 		goto ignore;

 	if (reply && (rc->rc_seq_reply != seq))
 		goto ignore;

 	if (!(status & DLM_RS_NODES) && (names || lookup || lock))
 		goto ignore;

 	if (!(status & DLM_RS_DIR) && (lookup || lock))
 		goto ignore;

 	switch (rc->rc_type) {
 	case DLM_RCOM_STATUS:
 		receive_rcom_status(ls, rc);
 		break;

 	case DLM_RCOM_NAMES:
 		receive_rcom_names(ls, rc);
 		break;

 	case DLM_RCOM_LOOKUP:
 		receive_rcom_lookup(ls, rc);
 		break;

 	case DLM_RCOM_LOCK:
 		if (rc->rc_header.h_length < lock_size)
 			goto Eshort;
 		receive_rcom_lock(ls, rc);
 		break;

 	case DLM_RCOM_STATUS_REPLY:
 		receive_sync_reply(ls, rc);
 		break;

 	case DLM_RCOM_NAMES_REPLY:
 		receive_sync_reply(ls, rc);
 		break;

 	case DLM_RCOM_LOOKUP_REPLY:
 		receive_rcom_lookup_reply(ls, rc);
 		break;

 	case DLM_RCOM_LOCK_REPLY:
 		if (rc->rc_header.h_length < lock_size)
 			goto Eshort;
 		dlm_recover_process_copy(ls, rc);
 		break;

 	default:
 		log_error(ls, "receive_rcom bad type %d", rc->rc_type);
 	}
 	return;

 ignore:
 	log_limit(ls, "dlm_receive_rcom ignore msg %d "
 		  "from %d %llu %llu recover seq %llu sts %x gen %u",
 		   rc->rc_type,
 		   nodeid,
 		   (unsigned long long)rc->rc_seq,
 		   (unsigned long long)rc->rc_seq_reply,
 		   (unsigned long long)seq,
 		   status, ls->ls_generation);
 	return;
 Eshort:
 	log_error(ls, "recovery message %d from %d is too short",
 		  rc->rc_type, nodeid);
 }
	/******************************************************************************
	*******************************************************************************
	**
	** Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
	** Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
	**
	** This copyrighted material is made available to anyone wishing to use,
	** modify, copy, or redistribute it subject to the terms and conditions
	** of the GNU General Public License v.2.
	**
	*******************************************************************************
	******************************************************************************/

	#include "dlm_internal.h"
	#include "lockspace.h"
	#include "member.h"
	#include "lowcomms.h"
	#include "midcomms.h"
	#include "rcom.h"
	#include "recover.h"
	#include "dir.h"
	#include "config.h"
	#include "memory.h"
	#include "lock.h"
	#include "util.h"

	static int rcom_response(struct dlm_ls *ls)
	{
	return test_bit(LSFL_RCOM_READY, &ls->ls_flags);
	}

	static int create_rcom(struct dlm_ls *ls, int to_nodeid, int type, int len,
	struct dlm_rcom rc_ret, struct dlm_mhandle mh_ret)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	char *mb;
	int mb_len = sizeof(struct dlm_rcom) + len;

	mh = dlm_lowcomms_get_buffer(to_nodeid, mb_len, GFP_NOFS, &mb);
	if (!mh) {
	log_print("create_rcom to %d type %d len %d ENOBUFS",
	to_nodeid, type, len);
	return -ENOBUFS;
	}
	memset(mb, 0, mb_len);

	rc = (struct dlm_rcom *) mb;

	rc->rc_header.h_version = (DLM_HEADER_MAJOR \| DLM_HEADER_MINOR);
	rc->rc_header.h_lockspace = ls->ls_global_id;
	rc->rc_header.h_nodeid = dlm_our_nodeid();
	rc->rc_header.h_length = mb_len;
	rc->rc_header.h_cmd = DLM_RCOM;

	rc->rc_type = type;

	spin_lock(&ls->ls_recover_lock);
	rc->rc_seq = ls->ls_recover_seq;
	spin_unlock(&ls->ls_recover_lock);

	*mh_ret = mh;
	*rc_ret = rc;
	return 0;
	}

	static void send_rcom(struct dlm_ls ls, struct dlm_mhandle mh,
	struct dlm_rcom *rc)
	{
	dlm_rcom_out(rc);
	dlm_lowcomms_commit_buffer(mh);
	}

	static void set_rcom_status(struct dlm_ls ls, struct rcom_status rs,
	uint32_t flags)
	{
	rs->rs_flags = cpu_to_le32(flags);
	}

	/* When replying to a status request, a node also sends back its
	configuration values. The requesting node then checks that the remote
	node is configured the same way as itself. */

	static void set_rcom_config(struct dlm_ls ls, struct rcom_config rf,
	uint32_t num_slots)
	{
	rf->rf_lvblen = cpu_to_le32(ls->ls_lvblen);
	rf->rf_lsflags = cpu_to_le32(ls->ls_exflags);

	rf->rf_our_slot = cpu_to_le16(ls->ls_slot);
	rf->rf_num_slots = cpu_to_le16(num_slots);
	rf->rf_generation = cpu_to_le32(ls->ls_generation);
	}

	static int check_rcom_config(struct dlm_ls ls, struct dlm_rcom rc, int nodeid)
	{
	struct rcom_config rf = (struct rcom_config ) rc->rc_buf;

	if ((rc->rc_header.h_version & 0xFFFF0000) != DLM_HEADER_MAJOR) {
	log_error(ls, "version mismatch: %x nodeid %d: %x",
	DLM_HEADER_MAJOR \| DLM_HEADER_MINOR, nodeid,
	rc->rc_header.h_version);
	return -EPROTO;
	}

	if (le32_to_cpu(rf->rf_lvblen) != ls->ls_lvblen \|\|
	le32_to_cpu(rf->rf_lsflags) != ls->ls_exflags) {
	log_error(ls, "config mismatch: %d,%x nodeid %d: %d,%x",
	ls->ls_lvblen, ls->ls_exflags, nodeid,
	le32_to_cpu(rf->rf_lvblen),
	le32_to_cpu(rf->rf_lsflags));
	return -EPROTO;
	}
	return 0;
	}

	static void allow_sync_reply(struct dlm_ls ls, uint64_t new_seq)
	{
	spin_lock(&ls->ls_rcom_spin);
	*new_seq = ++ls->ls_rcom_seq;
	set_bit(LSFL_RCOM_WAIT, &ls->ls_flags);
	spin_unlock(&ls->ls_rcom_spin);
	}

	static void disallow_sync_reply(struct dlm_ls *ls)
	{
	spin_lock(&ls->ls_rcom_spin);
	clear_bit(LSFL_RCOM_WAIT, &ls->ls_flags);
	clear_bit(LSFL_RCOM_READY, &ls->ls_flags);
	spin_unlock(&ls->ls_rcom_spin);
	}

	/*
	* low nodeid gathers one slot value at a time from each node.
	* it sets need_slots=0, and saves rf_our_slot returned from each
	* rcom_config.
	*
	* other nodes gather all slot values at once from the low nodeid.
	* they set need_slots=1, and ignore the rf_our_slot returned from each
	* rcom_config. they use the rf_num_slots returned from the low
	* node's rcom_config.
	*/

	int dlm_rcom_status(struct dlm_ls *ls, int nodeid, uint32_t status_flags)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	int error = 0;

	ls->ls_recover_nodeid = nodeid;

	if (nodeid == dlm_our_nodeid()) {
	rc = ls->ls_recover_buf;
	rc->rc_result = dlm_recover_status(ls);
	goto out;
	}

	error = create_rcom(ls, nodeid, DLM_RCOM_STATUS,
	sizeof(struct rcom_status), &rc, &mh);
	if (error)
	goto out;

	set_rcom_status(ls, (struct rcom_status *)rc->rc_buf, status_flags);

	allow_sync_reply(ls, &rc->rc_id);
	memset(ls->ls_recover_buf, 0, dlm_config.ci_buffer_size);

	send_rcom(ls, mh, rc);

	error = dlm_wait_function(ls, &rcom_response);
	disallow_sync_reply(ls);
	if (error)
	goto out;

	rc = ls->ls_recover_buf;

	if (rc->rc_result == -ESRCH) {
	/* we pretend the remote lockspace exists with 0 status */
	log_debug(ls, "remote node %d not ready", nodeid);
	rc->rc_result = 0;
	error = 0;
	} else {
	error = check_rcom_config(ls, rc, nodeid);
	}

	/* the caller looks at rc_result for the remote recovery status */
	out:
	return error;
	}

	static void receive_rcom_status(struct dlm_ls ls, struct dlm_rcom rc_in)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	struct rcom_status *rs;
	uint32_t status;
	int nodeid = rc_in->rc_header.h_nodeid;
	int len = sizeof(struct rcom_config);
	int num_slots = 0;
	int error;

	if (!dlm_slots_version(&rc_in->rc_header)) {
	status = dlm_recover_status(ls);
	goto do_create;
	}

	rs = (struct rcom_status *)rc_in->rc_buf;

	if (!(rs->rs_flags & DLM_RSF_NEED_SLOTS)) {
	status = dlm_recover_status(ls);
	goto do_create;
	}

	spin_lock(&ls->ls_recover_lock);
	status = ls->ls_recover_status;
	num_slots = ls->ls_num_slots;
	spin_unlock(&ls->ls_recover_lock);
	len += num_slots * sizeof(struct rcom_slot);

	do_create:
	error = create_rcom(ls, nodeid, DLM_RCOM_STATUS_REPLY,
	len, &rc, &mh);
	if (error)
	return;

	rc->rc_id = rc_in->rc_id;
	rc->rc_seq_reply = rc_in->rc_seq;
	rc->rc_result = status;

	set_rcom_config(ls, (struct rcom_config *)rc->rc_buf, num_slots);

	if (!num_slots)
	goto do_send;

	spin_lock(&ls->ls_recover_lock);
	if (ls->ls_num_slots != num_slots) {
	spin_unlock(&ls->ls_recover_lock);
	log_debug(ls, "receive_rcom_status num_slots %d to %d",
	num_slots, ls->ls_num_slots);
	rc->rc_result = 0;
	set_rcom_config(ls, (struct rcom_config *)rc->rc_buf, 0);
	goto do_send;
	}

	dlm_slots_copy_out(ls, rc);
	spin_unlock(&ls->ls_recover_lock);

	do_send:
	send_rcom(ls, mh, rc);
	}

	static void receive_sync_reply(struct dlm_ls ls, struct dlm_rcom rc_in)
	{
	spin_lock(&ls->ls_rcom_spin);
	if (!test_bit(LSFL_RCOM_WAIT, &ls->ls_flags) \|\|
	rc_in->rc_id != ls->ls_rcom_seq) {
	log_debug(ls, "reject reply %d from %d seq %llx expect %llx",
	rc_in->rc_type, rc_in->rc_header.h_nodeid,
	(unsigned long long)rc_in->rc_id,
	(unsigned long long)ls->ls_rcom_seq);
	goto out;
	}
	memcpy(ls->ls_recover_buf, rc_in, rc_in->rc_header.h_length);
	set_bit(LSFL_RCOM_READY, &ls->ls_flags);
	clear_bit(LSFL_RCOM_WAIT, &ls->ls_flags);
	wake_up(&ls->ls_wait_general);
	out:
	spin_unlock(&ls->ls_rcom_spin);
	}

	int dlm_rcom_names(struct dlm_ls ls, int nodeid, char last_name, int last_len)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	int error = 0;

	ls->ls_recover_nodeid = nodeid;

	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES, last_len, &rc, &mh);
	if (error)
	goto out;
	memcpy(rc->rc_buf, last_name, last_len);

	allow_sync_reply(ls, &rc->rc_id);
	memset(ls->ls_recover_buf, 0, dlm_config.ci_buffer_size);

	send_rcom(ls, mh, rc);

	error = dlm_wait_function(ls, &rcom_response);
	disallow_sync_reply(ls);
	out:
	return error;
	}

	static void receive_rcom_names(struct dlm_ls ls, struct dlm_rcom rc_in)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	int error, inlen, outlen, nodeid;

	nodeid = rc_in->rc_header.h_nodeid;
	inlen = rc_in->rc_header.h_length - sizeof(struct dlm_rcom);
	outlen = dlm_config.ci_buffer_size - sizeof(struct dlm_rcom);

	error = create_rcom(ls, nodeid, DLM_RCOM_NAMES_REPLY, outlen, &rc, &mh);
	if (error)
	return;
	rc->rc_id = rc_in->rc_id;
	rc->rc_seq_reply = rc_in->rc_seq;

	dlm_copy_master_names(ls, rc_in->rc_buf, inlen, rc->rc_buf, outlen,
	nodeid);
	send_rcom(ls, mh, rc);
	}

	int dlm_send_rcom_lookup(struct dlm_rsb *r, int dir_nodeid)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	struct dlm_ls *ls = r->res_ls;
	int error;

	error = create_rcom(ls, dir_nodeid, DLM_RCOM_LOOKUP, r->res_length,
	&rc, &mh);
	if (error)
	goto out;
	memcpy(rc->rc_buf, r->res_name, r->res_length);
	rc->rc_id = (unsigned long) r->res_id;

	send_rcom(ls, mh, rc);
	out:
	return error;
	}

	int dlm_send_rcom_lookup_dump(struct dlm_rsb *r, int to_nodeid)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	struct dlm_ls *ls = r->res_ls;
	int error;

	error = create_rcom(ls, to_nodeid, DLM_RCOM_LOOKUP, r->res_length,
	&rc, &mh);
	if (error)
	goto out;
	memcpy(rc->rc_buf, r->res_name, r->res_length);
	rc->rc_id = 0xFFFFFFFF;

	send_rcom(ls, mh, rc);
	out:
	return error;
	}

	static void receive_rcom_lookup(struct dlm_ls ls, struct dlm_rcom rc_in)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	int error, ret_nodeid, nodeid = rc_in->rc_header.h_nodeid;
	int len = rc_in->rc_header.h_length - sizeof(struct dlm_rcom);

	error = create_rcom(ls, nodeid, DLM_RCOM_LOOKUP_REPLY, 0, &rc, &mh);
	if (error)
	return;

	if (rc_in->rc_id == 0xFFFFFFFF) {
	log_error(ls, "receive_rcom_lookup dump from %d", nodeid);
	dlm_dump_rsb_name(ls, rc_in->rc_buf, len);
	return;
	}

	error = dlm_master_lookup(ls, nodeid, rc_in->rc_buf, len,
	DLM_LU_RECOVER_MASTER, &ret_nodeid, NULL);
	if (error)
	ret_nodeid = error;
	rc->rc_result = ret_nodeid;
	rc->rc_id = rc_in->rc_id;
	rc->rc_seq_reply = rc_in->rc_seq;

	send_rcom(ls, mh, rc);
	}

	static void receive_rcom_lookup_reply(struct dlm_ls ls, struct dlm_rcom rc_in)
	{
	dlm_recover_master_reply(ls, rc_in);
	}

	static void pack_rcom_lock(struct dlm_rsb r, struct dlm_lkb lkb,
	struct rcom_lock *rl)
	{
	memset(rl, 0, sizeof(*rl));

	rl->rl_ownpid = cpu_to_le32(lkb->lkb_ownpid);
	rl->rl_lkid = cpu_to_le32(lkb->lkb_id);
	rl->rl_exflags = cpu_to_le32(lkb->lkb_exflags);
	rl->rl_flags = cpu_to_le32(lkb->lkb_flags);
	rl->rl_lvbseq = cpu_to_le32(lkb->lkb_lvbseq);
	rl->rl_rqmode = lkb->lkb_rqmode;
	rl->rl_grmode = lkb->lkb_grmode;
	rl->rl_status = lkb->lkb_status;
	rl->rl_wait_type = cpu_to_le16(lkb->lkb_wait_type);

	if (lkb->lkb_bastfn)
	rl->rl_asts \|= DLM_CB_BAST;
	if (lkb->lkb_astfn)
	rl->rl_asts \|= DLM_CB_CAST;

	rl->rl_namelen = cpu_to_le16(r->res_length);
	memcpy(rl->rl_name, r->res_name, r->res_length);

	/* FIXME: might we have an lvb without DLM_LKF_VALBLK set ?
	If so, receive_rcom_lock_args() won't take this copy. */

	if (lkb->lkb_lvbptr)
	memcpy(rl->rl_lvb, lkb->lkb_lvbptr, r->res_ls->ls_lvblen);
	}

	int dlm_send_rcom_lock(struct dlm_rsb r, struct dlm_lkb lkb)
	{
	struct dlm_ls *ls = r->res_ls;
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	struct rcom_lock *rl;
	int error, len = sizeof(struct rcom_lock);

	if (lkb->lkb_lvbptr)
	len += ls->ls_lvblen;

	error = create_rcom(ls, r->res_nodeid, DLM_RCOM_LOCK, len, &rc, &mh);
	if (error)
	goto out;

	rl = (struct rcom_lock *) rc->rc_buf;
	pack_rcom_lock(r, lkb, rl);
	rc->rc_id = (unsigned long) r;

	send_rcom(ls, mh, rc);
	out:
	return error;
	}

	/* needs at least dlm_rcom + rcom_lock */
	static void receive_rcom_lock(struct dlm_ls ls, struct dlm_rcom rc_in)
	{
	struct dlm_rcom *rc;
	struct dlm_mhandle *mh;
	int error, nodeid = rc_in->rc_header.h_nodeid;

	dlm_recover_master_copy(ls, rc_in);

	error = create_rcom(ls, nodeid, DLM_RCOM_LOCK_REPLY,
	sizeof(struct rcom_lock), &rc, &mh);
	if (error)
	return;

	/* We send back the same rcom_lock struct we received, but
	dlm_recover_master_copy() has filled in rl_remid and rl_result */

	memcpy(rc->rc_buf, rc_in->rc_buf, sizeof(struct rcom_lock));
	rc->rc_id = rc_in->rc_id;
	rc->rc_seq_reply = rc_in->rc_seq;

	send_rcom(ls, mh, rc);
	}

	/* If the lockspace doesn't exist then still send a status message
	back; it's possible that it just doesn't have its global_id yet. */

	int dlm_send_ls_not_ready(int nodeid, struct dlm_rcom *rc_in)
	{
	struct dlm_rcom *rc;
	struct rcom_config *rf;
	struct dlm_mhandle *mh;
	char *mb;
	int mb_len = sizeof(struct dlm_rcom) + sizeof(struct rcom_config);

	mh = dlm_lowcomms_get_buffer(nodeid, mb_len, GFP_NOFS, &mb);
	if (!mh)
	return -ENOBUFS;
	memset(mb, 0, mb_len);

	rc = (struct dlm_rcom *) mb;

	rc->rc_header.h_version = (DLM_HEADER_MAJOR \| DLM_HEADER_MINOR);
	rc->rc_header.h_lockspace = rc_in->rc_header.h_lockspace;
	rc->rc_header.h_nodeid = dlm_our_nodeid();
	rc->rc_header.h_length = mb_len;
	rc->rc_header.h_cmd = DLM_RCOM;

	rc->rc_type = DLM_RCOM_STATUS_REPLY;
	rc->rc_id = rc_in->rc_id;
	rc->rc_seq_reply = rc_in->rc_seq;
	rc->rc_result = -ESRCH;

	rf = (struct rcom_config *) rc->rc_buf;
	rf->rf_lvblen = cpu_to_le32(~0U);

	dlm_rcom_out(rc);
	dlm_lowcomms_commit_buffer(mh);

	return 0;
	}

	/*
	* Ignore messages for stage Y before we set
	* recover_status bit for stage X:
	*
	* recover_status = 0
	*
	* dlm_recover_members()
	* - send nothing
	* - recv nothing
	* - ignore NAMES, NAMES_REPLY
	* - ignore LOOKUP, LOOKUP_REPLY
	* - ignore LOCK, LOCK_REPLY
	*
	* recover_status \|= NODES
	*
	* dlm_recover_members_wait()
	*
	* dlm_recover_directory()
	* - send NAMES
	* - recv NAMES_REPLY
	* - ignore LOOKUP, LOOKUP_REPLY
	* - ignore LOCK, LOCK_REPLY
	*
	* recover_status \|= DIR
	*
	* dlm_recover_directory_wait()
	*
	* dlm_recover_masters()
	* - send LOOKUP
	* - recv LOOKUP_REPLY
	*
	* dlm_recover_locks()
	* - send LOCKS
	* - recv LOCKS_REPLY
	*
	* recover_status \|= LOCKS
	*
	* dlm_recover_locks_wait()
	*
	* recover_status \|= DONE
	*/

	/* Called by dlm_recv; corresponds to dlm_receive_message() but special
	recovery-only comms are sent through here. */

	void dlm_receive_rcom(struct dlm_ls ls, struct dlm_rcom rc, int nodeid)
	{
	int lock_size = sizeof(struct dlm_rcom) + sizeof(struct rcom_lock);
	int stop, reply = 0, names = 0, lookup = 0, lock = 0;
	uint32_t status;
	uint64_t seq;

	switch (rc->rc_type) {
	case DLM_RCOM_STATUS_REPLY:
	reply = 1;
	break;
	case DLM_RCOM_NAMES:
	names = 1;
	break;
	case DLM_RCOM_NAMES_REPLY:
	names = 1;
	reply = 1;
	break;
	case DLM_RCOM_LOOKUP:
	lookup = 1;
	break;
	case DLM_RCOM_LOOKUP_REPLY:
	lookup = 1;
	reply = 1;
	break;
	case DLM_RCOM_LOCK:
	lock = 1;
	break;
	case DLM_RCOM_LOCK_REPLY:
	lock = 1;
	reply = 1;
	break;
	};

	spin_lock(&ls->ls_recover_lock);
	status = ls->ls_recover_status;
	stop = test_bit(LSFL_RECOVER_STOP, &ls->ls_flags);
	seq = ls->ls_recover_seq;
	spin_unlock(&ls->ls_recover_lock);

	if (stop && (rc->rc_type != DLM_RCOM_STATUS))
	goto ignore;

	if (reply && (rc->rc_seq_reply != seq))
	goto ignore;

	if (!(status & DLM_RS_NODES) && (names \|\| lookup \|\| lock))
	goto ignore;

	if (!(status & DLM_RS_DIR) && (lookup \|\| lock))
	goto ignore;

	switch (rc->rc_type) {
	case DLM_RCOM_STATUS:
	receive_rcom_status(ls, rc);
	break;

	case DLM_RCOM_NAMES:
	receive_rcom_names(ls, rc);
	break;

	case DLM_RCOM_LOOKUP:
	receive_rcom_lookup(ls, rc);
	break;

	case DLM_RCOM_LOCK:
	if (rc->rc_header.h_length < lock_size)
	goto Eshort;
	receive_rcom_lock(ls, rc);
	break;

	case DLM_RCOM_STATUS_REPLY:
	receive_sync_reply(ls, rc);
	break;

	case DLM_RCOM_NAMES_REPLY:
	receive_sync_reply(ls, rc);
	break;

	case DLM_RCOM_LOOKUP_REPLY:
	receive_rcom_lookup_reply(ls, rc);
	break;

	case DLM_RCOM_LOCK_REPLY:
	if (rc->rc_header.h_length < lock_size)
	goto Eshort;
	dlm_recover_process_copy(ls, rc);
	break;

	default:
	log_error(ls, "receive_rcom bad type %d", rc->rc_type);
	}
	return;

	ignore:
	log_limit(ls, "dlm_receive_rcom ignore msg %d "
	"from %d %llu %llu recover seq %llu sts %x gen %u",
	rc->rc_type,
	nodeid,
	(unsigned long long)rc->rc_seq,
	(unsigned long long)rc->rc_seq_reply,
	(unsigned long long)seq,
	status, ls->ls_generation);
	return;
	Eshort:
	log_error(ls, "recovery message %d from %d is too short",
	rc->rc_type, nodeid);
	}