/*
 * 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.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2007, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2013, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/fld/fld_request.c
 *
 * FLD (Fids Location Database)
 *
 * Author: Yury Umanets <umka@clusterfs.com>
 */

#define DEBUG_SUBSYSTEM S_FLD

#include <libcfs/libcfs.h>
#include <linux/module.h>
#include <linux/math64.h>

#include <obd.h>
#include <obd_class.h>
#include <obd_support.h>
#include <lprocfs_status.h>
#include <lustre_req_layout.h>
#include <lustre_fld.h>
#include <lustre_mdc.h>
#include "fld_internal.h"

static int fld_rrb_hash(struct lu_client_fld *fld, u64 seq)
{
	LASSERT(fld->lcf_count > 0);
	return do_div(seq, fld->lcf_count);
}

static struct lu_fld_target *
fld_rrb_scan(struct lu_client_fld *fld, u64 seq)
{
        struct lu_fld_target *target;
        int hash;
        ENTRY;

	/* Because almost all of special sequence located in MDT0,
	 * it should go to index 0 directly, instead of calculating
	 * hash again, and also if other MDTs is not being connected,
	 * the fld lookup requests(for seq on MDT0) should not be
	 * blocked because of other MDTs */
	if (fid_seq_is_norm(seq))
		hash = fld_rrb_hash(fld, seq);
	else
		hash = 0;

again:
	list_for_each_entry(target, &fld->lcf_targets, ft_chain) {
                if (target->ft_idx == hash)
                        RETURN(target);
        }

	if (hash != 0) {
		/* It is possible the remote target(MDT) are not connected to
		 * with client yet, so we will refer this to MDT0, which should
		 * be connected during mount */
		hash = 0;
		goto again;
	}

        CERROR("%s: Can't find target by hash %d (seq "LPX64"). "
               "Targets (%d):\n", fld->lcf_name, hash, seq,
               fld->lcf_count);

	list_for_each_entry(target, &fld->lcf_targets, ft_chain) {
                const char *srv_name = target->ft_srv != NULL  ?
                        target->ft_srv->lsf_name : "<null>";
                const char *exp_name = target->ft_exp != NULL ?
                        (char *)target->ft_exp->exp_obd->obd_uuid.uuid :
                        "<null>";

                CERROR("  exp: 0x%p (%s), srv: 0x%p (%s), idx: "LPU64"\n",
                       target->ft_exp, exp_name, target->ft_srv,
                       srv_name, target->ft_idx);
        }

        /*
         * If target is not found, there is logical error anyway, so here is
         * LBUG() to catch this situation.
         */
        LBUG();
        RETURN(NULL);
}

struct lu_fld_hash fld_hash[] = {
        {
                .fh_name = "RRB",
                .fh_hash_func = fld_rrb_hash,
                .fh_scan_func = fld_rrb_scan
        },
        {
                0,
        }
};

static struct lu_fld_target *
fld_client_get_target(struct lu_client_fld *fld, u64 seq)
{
	struct lu_fld_target *target;
	ENTRY;

	LASSERT(fld->lcf_hash != NULL);

	spin_lock(&fld->lcf_lock);
	target = fld->lcf_hash->fh_scan_func(fld, seq);
	spin_unlock(&fld->lcf_lock);

        if (target != NULL) {
                CDEBUG(D_INFO, "%s: Found target (idx "LPU64
                       ") by seq "LPX64"\n", fld->lcf_name,
                       target->ft_idx, seq);
        }

        RETURN(target);
}

/*
 * Add export to FLD. This is usually done by CMM and LMV as they are main users
 * of FLD module.
 */
int fld_client_add_target(struct lu_client_fld *fld,
                          struct lu_fld_target *tar)
{
	const char *name;
        struct lu_fld_target *target, *tmp;
        ENTRY;

        LASSERT(tar != NULL);
	name = fld_target_name(tar);
        LASSERT(name != NULL);
        LASSERT(tar->ft_srv != NULL || tar->ft_exp != NULL);

        if (fld->lcf_flags != LUSTRE_FLD_INIT) {
                CERROR("%s: Attempt to add target %s (idx "LPU64") "
                       "on fly - skip it\n", fld->lcf_name, name,
                       tar->ft_idx);
                RETURN(0);
        } else {
                CDEBUG(D_INFO, "%s: Adding target %s (idx "
                       LPU64")\n", fld->lcf_name, name, tar->ft_idx);
        }

        OBD_ALLOC_PTR(target);
        if (target == NULL)
                RETURN(-ENOMEM);

	spin_lock(&fld->lcf_lock);
	list_for_each_entry(tmp, &fld->lcf_targets, ft_chain) {
		if (tmp->ft_idx == tar->ft_idx) {
			spin_unlock(&fld->lcf_lock);
                        OBD_FREE_PTR(target);
                        CERROR("Target %s exists in FLD and known as %s:#"LPU64"\n",
                               name, fld_target_name(tmp), tmp->ft_idx);
                        RETURN(-EEXIST);
                }
        }

        target->ft_exp = tar->ft_exp;
        if (target->ft_exp != NULL)
                class_export_get(target->ft_exp);
        target->ft_srv = tar->ft_srv;
        target->ft_idx = tar->ft_idx;

	list_add_tail(&target->ft_chain, &fld->lcf_targets);

        fld->lcf_count++;
	spin_unlock(&fld->lcf_lock);

	RETURN(0);
}
EXPORT_SYMBOL(fld_client_add_target);

/* Remove export from FLD */
int fld_client_del_target(struct lu_client_fld *fld, __u64 idx)
{
	struct lu_fld_target *target, *tmp;
	ENTRY;

	spin_lock(&fld->lcf_lock);
	list_for_each_entry_safe(target, tmp, &fld->lcf_targets, ft_chain) {
		if (target->ft_idx == idx) {
			fld->lcf_count--;
			list_del(&target->ft_chain);
			spin_unlock(&fld->lcf_lock);

                        if (target->ft_exp != NULL)
                                class_export_put(target->ft_exp);

                        OBD_FREE_PTR(target);
                        RETURN(0);
                }
        }
	spin_unlock(&fld->lcf_lock);
	RETURN(-ENOENT);
}
EXPORT_SYMBOL(fld_client_del_target);

#ifdef LPROCFS
static int fld_client_proc_init(struct lu_client_fld *fld)
{
	int rc;
	ENTRY;

	fld->lcf_proc_dir = lprocfs_seq_register(fld->lcf_name,
						 fld_type_proc_dir,
						 NULL, NULL);
	if (IS_ERR(fld->lcf_proc_dir)) {
		CERROR("%s: LProcFS failed in fld-init\n",
		       fld->lcf_name);
		rc = PTR_ERR(fld->lcf_proc_dir);
		RETURN(rc);
	}

	rc = lprocfs_seq_add_vars(fld->lcf_proc_dir,
				  fld_client_proc_list, fld);
	if (rc) {
		CERROR("%s: Can't init FLD proc, rc %d\n",
		       fld->lcf_name, rc);
		GOTO(out_cleanup, rc);
	}

	RETURN(0);

out_cleanup:
	fld_client_proc_fini(fld);
	return rc;
}

void fld_client_proc_fini(struct lu_client_fld *fld)
{
        ENTRY;
        if (fld->lcf_proc_dir) {
                if (!IS_ERR(fld->lcf_proc_dir))
                        lprocfs_remove(&fld->lcf_proc_dir);
                fld->lcf_proc_dir = NULL;
        }
        EXIT;
}
#else /* LPROCFS */
static int fld_client_proc_init(struct lu_client_fld *fld)
{
        return 0;
}

void fld_client_proc_fini(struct lu_client_fld *fld)
{
        return;
}
#endif /* !LPROCFS */

EXPORT_SYMBOL(fld_client_proc_fini);

static inline int hash_is_sane(int hash)
{
        return (hash >= 0 && hash < ARRAY_SIZE(fld_hash));
}

int fld_client_init(struct lu_client_fld *fld,
                    const char *prefix, int hash)
{
        int cache_size, cache_threshold;
        int rc;
        ENTRY;

        LASSERT(fld != NULL);

        snprintf(fld->lcf_name, sizeof(fld->lcf_name),
                 "cli-%s", prefix);

        if (!hash_is_sane(hash)) {
                CERROR("%s: Wrong hash function %#x\n",
                       fld->lcf_name, hash);
                RETURN(-EINVAL);
        }

        fld->lcf_count = 0;
	spin_lock_init(&fld->lcf_lock);
        fld->lcf_hash = &fld_hash[hash];
        fld->lcf_flags = LUSTRE_FLD_INIT;
	INIT_LIST_HEAD(&fld->lcf_targets);

        cache_size = FLD_CLIENT_CACHE_SIZE /
                sizeof(struct fld_cache_entry);

        cache_threshold = cache_size *
                FLD_CLIENT_CACHE_THRESHOLD / 100;

        fld->lcf_cache = fld_cache_init(fld->lcf_name,
                                        cache_size, cache_threshold);
        if (IS_ERR(fld->lcf_cache)) {
                rc = PTR_ERR(fld->lcf_cache);
                fld->lcf_cache = NULL;
                GOTO(out, rc);
        }

        rc = fld_client_proc_init(fld);
        if (rc)
                GOTO(out, rc);
        EXIT;
out:
        if (rc)
                fld_client_fini(fld);
        else
                CDEBUG(D_INFO, "%s: Using \"%s\" hash\n",
                       fld->lcf_name, fld->lcf_hash->fh_name);
        return rc;
}
EXPORT_SYMBOL(fld_client_init);

void fld_client_fini(struct lu_client_fld *fld)
{
	struct lu_fld_target *target, *tmp;
	ENTRY;

	spin_lock(&fld->lcf_lock);
	list_for_each_entry_safe(target, tmp, &fld->lcf_targets, ft_chain) {
                fld->lcf_count--;
		list_del(&target->ft_chain);
                if (target->ft_exp != NULL)
                        class_export_put(target->ft_exp);
                OBD_FREE_PTR(target);
        }
	spin_unlock(&fld->lcf_lock);

        if (fld->lcf_cache != NULL) {
                if (!IS_ERR(fld->lcf_cache))
                        fld_cache_fini(fld->lcf_cache);
                fld->lcf_cache = NULL;
        }

        EXIT;
}
EXPORT_SYMBOL(fld_client_fini);

int fld_client_rpc(struct obd_export *exp,
		   struct lu_seq_range *range, __u32 fld_op,
		   struct ptlrpc_request **reqp)
{
	struct ptlrpc_request *req = NULL;
	struct lu_seq_range   *prange;
	__u32                 *op;
	int                    rc = 0;
	struct obd_import     *imp;
	ENTRY;

	LASSERT(exp != NULL);

again:
	imp = class_exp2cliimp(exp);
	switch (fld_op) {
	case FLD_QUERY:
		req = ptlrpc_request_alloc_pack(imp, &RQF_FLD_QUERY,
						LUSTRE_MDS_VERSION, FLD_QUERY);
		if (req == NULL)
			RETURN(-ENOMEM);

		/* XXX: only needed when talking to old server(< 2.6), it should
		 * be removed when < 2.6 server is not supported */
		op = req_capsule_client_get(&req->rq_pill, &RMF_FLD_OPC);
		*op = FLD_LOOKUP;

		/* For MDS_MDS seq lookup, it will always use LWP connection,
		 * but LWP will be evicted after restart, so cause the error.
		 * so we will set no_delay for seq lookup request, once the
		 * request fails because of the eviction. always retry here */
		if (imp->imp_connect_flags_orig & OBD_CONNECT_MDS_MDS) {
			req->rq_allow_replay = 1;
			req->rq_no_delay = 1;
		}
		break;
	case FLD_READ:
		req = ptlrpc_request_alloc_pack(imp, &RQF_FLD_READ,
						LUSTRE_MDS_VERSION, FLD_READ);
		if (req == NULL)
			RETURN(-ENOMEM);

		req_capsule_set_size(&req->rq_pill, &RMF_GENERIC_DATA,
				     RCL_SERVER, PAGE_CACHE_SIZE);
		break;
	default:
		rc = -EINVAL;
		break;
	}

	if (rc != 0)
		RETURN(rc);

	prange = req_capsule_client_get(&req->rq_pill, &RMF_FLD_MDFLD);
	*prange = *range;
	ptlrpc_request_set_replen(req);
        req->rq_request_portal = FLD_REQUEST_PORTAL;
	req->rq_reply_portal = MDC_REPLY_PORTAL;
        ptlrpc_at_set_req_timeout(req);

	obd_get_request_slot(&exp->exp_obd->u.cli);
	rc = ptlrpc_queue_wait(req);
	obd_put_request_slot(&exp->exp_obd->u.cli);
	if (rc != 0) {
		if (imp->imp_state != LUSTRE_IMP_CLOSED) {
			/* Since LWP is not replayable, so it will keep
			 * trying unless umount happens, otherwise it would
			 * cause unecessary failure of the application. */
			ptlrpc_req_finished(req);
			rc = 0;
			goto again;
		}
		GOTO(out_req, rc);
	}

	if (fld_op == FLD_QUERY) {
		prange = req_capsule_server_get(&req->rq_pill,
						&RMF_FLD_MDFLD);
		if (prange == NULL)
			GOTO(out_req, rc = -EFAULT);
		*range = *prange;
	}

	EXIT;
out_req:
	if (rc != 0 || reqp == NULL) {
		ptlrpc_req_finished(req);
		req = NULL;
	}

	if (reqp != NULL)
		*reqp = req;

	return rc;
}

int fld_client_lookup(struct lu_client_fld *fld, u64 seq, u32 *mds,
		      __u32 flags, const struct lu_env *env)
{
	struct lu_seq_range res = { 0 };
	struct lu_fld_target *target;
	int rc;
	ENTRY;

        fld->lcf_flags |= LUSTRE_FLD_RUN;

        rc = fld_cache_lookup(fld->lcf_cache, seq, &res);
        if (rc == 0) {
                *mds = res.lsr_index;
                RETURN(0);
        }

        /* Can not find it in the cache */
        target = fld_client_get_target(fld, seq);
        LASSERT(target != NULL);

        CDEBUG(D_INFO, "%s: Lookup fld entry (seq: "LPX64") on "
               "target %s (idx "LPU64")\n", fld->lcf_name, seq,
               fld_target_name(target), target->ft_idx);

	res.lsr_start = seq;
	fld_range_set_type(&res, flags);

#ifdef HAVE_SERVER_SUPPORT
	if (target->ft_srv != NULL) {
		LASSERT(env != NULL);
		rc = fld_server_lookup(env, target->ft_srv, seq, &res);
	} else
#endif /* HAVE_SERVER_SUPPORT */
	{
		rc = fld_client_rpc(target->ft_exp, &res, FLD_QUERY, NULL);
	}

	if (rc == 0) {
		*mds = res.lsr_index;
		fld_cache_insert(fld->lcf_cache, &res);
	}

	RETURN(rc);
}
EXPORT_SYMBOL(fld_client_lookup);

void fld_client_flush(struct lu_client_fld *fld)
{
        fld_cache_flush(fld->lcf_cache);
}
EXPORT_SYMBOL(fld_client_flush);


struct proc_dir_entry *fld_type_proc_dir;

static int __init fld_mod_init(void)
{
	fld_type_proc_dir = lprocfs_seq_register(LUSTRE_FLD_NAME,
						 proc_lustre_root,
						 NULL, NULL);
	if (IS_ERR(fld_type_proc_dir))
		return PTR_ERR(fld_type_proc_dir);

#ifdef HAVE_SERVER_SUPPORT
	fld_server_mod_init();
#endif /* HAVE_SERVER_SUPPORT */

	return 0;
}

static void __exit fld_mod_exit(void)
{
#ifdef HAVE_SERVER_SUPPORT
	fld_server_mod_exit();
#endif /* HAVE_SERVER_SUPPORT */

	if (fld_type_proc_dir != NULL && !IS_ERR(fld_type_proc_dir)) {
		lprocfs_remove(&fld_type_proc_dir);
		fld_type_proc_dir = NULL;
	}
}

MODULE_AUTHOR("Sun Microsystems, Inc. <http://www.lustre.org/>");
MODULE_DESCRIPTION("Lustre FLD");
MODULE_LICENSE("GPL");

cfs_module(mdd, LUSTRE_VERSION_STRING, fld_mod_init, fld_mod_exit);