/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/ptlrpc/llog_client.c
 *
 * remote api for llog - client side
 *
 * Author: Andreas Dilger <adilger@clusterfs.com>
 */

#define DEBUG_SUBSYSTEM S_LOG

#include <linux/libcfs/libcfs.h>

#include <obd_class.h>
#include <lustre_log.h>
#include <lustre_net.h>
#include <linux/list.h>

#define LLOG_CLIENT_ENTRY(ctxt, imp) do {				\
	mutex_lock(&ctxt->loc_mutex);					\
	if (ctxt->loc_imp) {						\
		imp = class_import_get(ctxt->loc_imp);			\
	} else {							\
		CERROR("ctxt->loc_imp == NULL for context idx %d."	\
		       "Unable to complete MDS/OSS recovery,"		\
		       "but I'll try again next time.  Not fatal.\n",	\
		       ctxt->loc_idx);					\
		imp = NULL;						\
		mutex_unlock(&ctxt->loc_mutex);				\
		return (-EINVAL);					\
	}								\
	mutex_unlock(&ctxt->loc_mutex);					\
} while (0)

#define LLOG_CLIENT_EXIT(ctxt, imp) do {				\
	mutex_lock(&ctxt->loc_mutex);					\
	if (ctxt->loc_imp != imp)					\
		CWARN("loc_imp has changed from %p to %p\n",		\
		       ctxt->loc_imp, imp);				\
	class_import_put(imp);						\
	mutex_unlock(&ctxt->loc_mutex);					\
} while (0)

/* This is a callback from the llog_* functions.
 * Assumes caller has already pushed us into the kernel context.
 */
static int llog_client_open(const struct lu_env *env,
			    struct llog_handle *lgh, struct llog_logid *logid,
			    char *name, enum llog_open_param open_param)
{
	struct obd_import *imp;
	struct llogd_body *body;
	struct llog_ctxt *ctxt = lgh->lgh_ctxt;
	struct ptlrpc_request *req = NULL;
	int rc;

	LLOG_CLIENT_ENTRY(ctxt, imp);

	/* client cannot create llog */
	LASSERTF(open_param != LLOG_OPEN_NEW, "%#x\n", open_param);
	LASSERT(lgh);

	req = ptlrpc_request_alloc(imp, &RQF_LLOG_ORIGIN_HANDLE_CREATE);
	if (!req) {
		rc = -ENOMEM;
		goto out;
	}

	if (name)
		req_capsule_set_size(&req->rq_pill, &RMF_NAME, RCL_CLIENT,
				     strlen(name) + 1);

	rc = ptlrpc_request_pack(req, LUSTRE_LOG_VERSION,
				 LLOG_ORIGIN_HANDLE_CREATE);
	if (rc) {
		ptlrpc_request_free(req);
		req = NULL;
		goto out;
	}
	ptlrpc_request_set_replen(req);

	body = req_capsule_client_get(&req->rq_pill, &RMF_LLOGD_BODY);
	if (logid)
		body->lgd_logid = *logid;
	body->lgd_ctxt_idx = ctxt->loc_idx - 1;

	if (name) {
		char *tmp;

		tmp = req_capsule_client_sized_get(&req->rq_pill, &RMF_NAME,
						   strlen(name) + 1);
		LASSERT(tmp);
		strcpy(tmp, name);
	}

	rc = ptlrpc_queue_wait(req);
	if (rc)
		goto out;

	body = req_capsule_server_get(&req->rq_pill, &RMF_LLOGD_BODY);
	if (!body) {
		rc = -EFAULT;
		goto out;
	}

	lgh->lgh_id = body->lgd_logid;
	lgh->lgh_ctxt = ctxt;
out:
	LLOG_CLIENT_EXIT(ctxt, imp);
	ptlrpc_req_finished(req);
	return rc;
}

static int llog_client_next_block(const struct lu_env *env,
				  struct llog_handle *loghandle,
				  int *cur_idx, int next_idx,
				  __u64 *cur_offset, void *buf, int len)
{
	struct obd_import *imp;
	struct ptlrpc_request *req = NULL;
	struct llogd_body *body;
	void *ptr;
	int rc;

	LLOG_CLIENT_ENTRY(loghandle->lgh_ctxt, imp);
	req = ptlrpc_request_alloc_pack(imp, &RQF_LLOG_ORIGIN_HANDLE_NEXT_BLOCK,
					LUSTRE_LOG_VERSION,
					LLOG_ORIGIN_HANDLE_NEXT_BLOCK);
	if (!req) {
		rc = -ENOMEM;
		goto err_exit;
	}

	body = req_capsule_client_get(&req->rq_pill, &RMF_LLOGD_BODY);
	body->lgd_logid = loghandle->lgh_id;
	body->lgd_ctxt_idx = loghandle->lgh_ctxt->loc_idx - 1;
	body->lgd_llh_flags = loghandle->lgh_hdr->llh_flags;
	body->lgd_index = next_idx;
	body->lgd_saved_index = *cur_idx;
	body->lgd_len = len;
	body->lgd_cur_offset = *cur_offset;

	req_capsule_set_size(&req->rq_pill, &RMF_EADATA, RCL_SERVER, len);
	ptlrpc_request_set_replen(req);
	rc = ptlrpc_queue_wait(req);
	if (rc)
		goto out;

	body = req_capsule_server_get(&req->rq_pill, &RMF_LLOGD_BODY);
	if (!body) {
		rc = -EFAULT;
		goto out;
	}

	/* The log records are swabbed as they are processed */
	ptr = req_capsule_server_get(&req->rq_pill, &RMF_EADATA);
	if (!ptr) {
		rc = -EFAULT;
		goto out;
	}

	*cur_idx = body->lgd_saved_index;
	*cur_offset = body->lgd_cur_offset;

	memcpy(buf, ptr, len);
out:
	ptlrpc_req_finished(req);
err_exit:
	LLOG_CLIENT_EXIT(loghandle->lgh_ctxt, imp);
	return rc;
}

static int llog_client_prev_block(const struct lu_env *env,
				  struct llog_handle *loghandle,
				  int prev_idx, void *buf, int len)
{
	struct obd_import *imp;
	struct ptlrpc_request *req = NULL;
	struct llogd_body *body;
	void *ptr;
	int rc;

	LLOG_CLIENT_ENTRY(loghandle->lgh_ctxt, imp);
	req = ptlrpc_request_alloc_pack(imp, &RQF_LLOG_ORIGIN_HANDLE_PREV_BLOCK,
					LUSTRE_LOG_VERSION,
					LLOG_ORIGIN_HANDLE_PREV_BLOCK);
	if (!req) {
		rc = -ENOMEM;
		goto err_exit;
	}

	body = req_capsule_client_get(&req->rq_pill, &RMF_LLOGD_BODY);
	body->lgd_logid = loghandle->lgh_id;
	body->lgd_ctxt_idx = loghandle->lgh_ctxt->loc_idx - 1;
	body->lgd_llh_flags = loghandle->lgh_hdr->llh_flags;
	body->lgd_index = prev_idx;
	body->lgd_len = len;

	req_capsule_set_size(&req->rq_pill, &RMF_EADATA, RCL_SERVER, len);
	ptlrpc_request_set_replen(req);

	rc = ptlrpc_queue_wait(req);
	if (rc)
		goto out;

	body = req_capsule_server_get(&req->rq_pill, &RMF_LLOGD_BODY);
	if (!body) {
		rc = -EFAULT;
		goto out;
	}

	ptr = req_capsule_server_get(&req->rq_pill, &RMF_EADATA);
	if (!ptr) {
		rc = -EFAULT;
		goto out;
	}

	memcpy(buf, ptr, len);
out:
	ptlrpc_req_finished(req);
err_exit:
	LLOG_CLIENT_EXIT(loghandle->lgh_ctxt, imp);
	return rc;
}

static int llog_client_read_header(const struct lu_env *env,
				   struct llog_handle *handle)
{
	struct obd_import *imp;
	struct ptlrpc_request *req = NULL;
	struct llogd_body *body;
	struct llog_log_hdr *hdr;
	struct llog_rec_hdr *llh_hdr;
	int rc;

	LLOG_CLIENT_ENTRY(handle->lgh_ctxt, imp);
	req = ptlrpc_request_alloc_pack(imp, &RQF_LLOG_ORIGIN_HANDLE_READ_HEADER,
					LUSTRE_LOG_VERSION,
					LLOG_ORIGIN_HANDLE_READ_HEADER);
	if (!req) {
		rc = -ENOMEM;
		goto err_exit;
	}

	body = req_capsule_client_get(&req->rq_pill, &RMF_LLOGD_BODY);
	body->lgd_logid = handle->lgh_id;
	body->lgd_ctxt_idx = handle->lgh_ctxt->loc_idx - 1;
	body->lgd_llh_flags = handle->lgh_hdr->llh_flags;

	ptlrpc_request_set_replen(req);
	rc = ptlrpc_queue_wait(req);
	if (rc)
		goto out;

	hdr = req_capsule_server_get(&req->rq_pill, &RMF_LLOG_LOG_HDR);
	if (!hdr) {
		rc = -EFAULT;
		goto out;
	}

	if (handle->lgh_hdr_size < hdr->llh_hdr.lrh_len) {
		rc = -EFAULT;
		goto out;
	}

	memcpy(handle->lgh_hdr, hdr, hdr->llh_hdr.lrh_len);
	handle->lgh_last_idx = LLOG_HDR_TAIL(handle->lgh_hdr)->lrt_index;

	/* sanity checks */
	llh_hdr = &handle->lgh_hdr->llh_hdr;
	if (llh_hdr->lrh_type != LLOG_HDR_MAGIC) {
		CERROR("bad log header magic: %#x (expecting %#x)\n",
		       llh_hdr->lrh_type, LLOG_HDR_MAGIC);
		rc = -EIO;
	} else if (llh_hdr->lrh_len !=
		   LLOG_HDR_TAIL(handle->lgh_hdr)->lrt_len ||
		   (llh_hdr->lrh_len & (llh_hdr->lrh_len - 1)) ||
		   llh_hdr->lrh_len < LLOG_MIN_CHUNK_SIZE ||
		   llh_hdr->lrh_len > handle->lgh_hdr_size) {
		CERROR("incorrectly sized log header: %#x (expecting %#x) (power of two > 8192)\n",
		       llh_hdr->lrh_len,
		       LLOG_HDR_TAIL(handle->lgh_hdr)->lrt_len);
		CERROR("you may need to re-run lconf --write_conf.\n");
		rc = -EIO;
	}
out:
	ptlrpc_req_finished(req);
err_exit:
	LLOG_CLIENT_EXIT(handle->lgh_ctxt, imp);
	return rc;
}

static int llog_client_close(const struct lu_env *env,
			     struct llog_handle *handle)
{
	/* this doesn't call LLOG_ORIGIN_HANDLE_CLOSE because
	 *  the servers all close the file at the end of every
	 * other LLOG_ RPC.
	 */
	return 0;
}

struct llog_operations llog_client_ops = {
	.lop_next_block		= llog_client_next_block,
	.lop_prev_block		= llog_client_prev_block,
	.lop_read_header	= llog_client_read_header,
	.lop_open		= llog_client_open,
	.lop_close		= llog_client_close,
};
EXPORT_SYMBOL(llog_client_ops);