/*
 * 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) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2015, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 */

#define DEBUG_SUBSYSTEM S_LOV

#include <libcfs/libcfs.h>

#include <obd_class.h>
#include <lustre/lustre_idl.h>

#include "lov_internal.h"

static void lov_init_set(struct lov_request_set *set)
{
	set->set_count = 0;
	atomic_set(&set->set_completes, 0);
	atomic_set(&set->set_success, 0);
	INIT_LIST_HEAD(&set->set_list);
}

static void lov_finish_set(struct lov_request_set *set)
{
	struct list_head *pos, *n;
	struct lov_request *req;
	ENTRY;

	LASSERT(set != NULL);
	list_for_each_safe(pos, n, &set->set_list) {
		req = list_entry(pos, struct lov_request, rq_link);
		list_del_init(&req->rq_link);

		if (req->rq_oi.oi_osfs != NULL)
			OBD_FREE_PTR(req->rq_oi.oi_osfs);

		OBD_FREE_PTR(req);
	}

	OBD_FREE_PTR(set);
	EXIT;
}

static void
lov_update_set(struct lov_request_set *set, struct lov_request *req, int rc)
{
	atomic_inc(&set->set_completes);
	if (rc == 0)
		atomic_inc(&set->set_success);
}

static void
lov_set_add_req(struct lov_request *req, struct lov_request_set *set)
{
	list_add_tail(&req->rq_link, &set->set_list);
        set->set_count++;
        req->rq_rqset = set;
}

static int lov_check_set(struct lov_obd *lov, int idx)
{
	int rc = 0;
	mutex_lock(&lov->lov_lock);

	if (lov->lov_tgts[idx] == NULL ||
	    lov->lov_tgts[idx]->ltd_active ||
	    (lov->lov_tgts[idx]->ltd_exp != NULL &&
	     class_exp2cliimp(lov->lov_tgts[idx]->ltd_exp)->imp_connect_tried))
		rc = 1;

	mutex_unlock(&lov->lov_lock);
	return rc;
}

/* Check if the OSC connection exists and is active.
 * If the OSC has not yet had a chance to connect to the OST the first time,
 * wait once for it to connect instead of returning an error.
 */
static int lov_check_and_wait_active(struct lov_obd *lov, int ost_idx)
{
	wait_queue_head_t waitq;
	struct l_wait_info lwi;
	struct lov_tgt_desc *tgt;
	int rc = 0;

	mutex_lock(&lov->lov_lock);

	tgt = lov->lov_tgts[ost_idx];

	if (unlikely(tgt == NULL))
		GOTO(out, rc = 0);

	if (likely(tgt->ltd_active))
		GOTO(out, rc = 1);

	if (tgt->ltd_exp && class_exp2cliimp(tgt->ltd_exp)->imp_connect_tried)
		GOTO(out, rc = 0);

	mutex_unlock(&lov->lov_lock);

	init_waitqueue_head(&waitq);
	lwi = LWI_TIMEOUT_INTERVAL(cfs_time_seconds(obd_timeout),
				   cfs_time_seconds(1), NULL, NULL);

	rc = l_wait_event(waitq, lov_check_set(lov, ost_idx), &lwi);
	if (tgt->ltd_active)
		return 1;

	return 0;

out:
	mutex_unlock(&lov->lov_lock);
	return rc;
}

#define LOV_U64_MAX ((__u64)~0ULL)
#define LOV_SUM_MAX(tot, add)                                           \
        do {                                                            \
                if ((tot) + (add) < (tot))                              \
                        (tot) = LOV_U64_MAX;                            \
                else                                                    \
                        (tot) += (add);                                 \
        } while(0)

static int
lov_fini_statfs(struct obd_device *obd, struct obd_statfs *osfs, int success)
{
        ENTRY;

        if (success) {
                __u32 expected_stripes = lov_get_stripecnt(&obd->u.lov,
                                                           LOV_MAGIC, 0);
		if (osfs->os_files != LOV_U64_MAX)
			lov_do_div64(osfs->os_files, expected_stripes);
		if (osfs->os_ffree != LOV_U64_MAX)
			lov_do_div64(osfs->os_ffree, expected_stripes);

		spin_lock(&obd->obd_osfs_lock);
		memcpy(&obd->obd_osfs, osfs, sizeof(*osfs));
		obd->obd_osfs_age = cfs_time_current_64();
		spin_unlock(&obd->obd_osfs_lock);
		RETURN(0);
	}

	RETURN(-EIO);
}

int lov_fini_statfs_set(struct lov_request_set *set)
{
	int rc = 0;
	ENTRY;

	if (set == NULL)
		RETURN(0);

	if (atomic_read(&set->set_completes)) {
		rc = lov_fini_statfs(set->set_obd, set->set_oi->oi_osfs,
				     atomic_read(&set->set_success));
	}

	lov_finish_set(set);

	RETURN(rc);
}

static void
lov_update_statfs(struct obd_statfs *osfs, struct obd_statfs *lov_sfs,
		  int success)
{
        int shift = 0, quit = 0;
        __u64 tmp;

        if (success == 0) {
                memcpy(osfs, lov_sfs, sizeof(*lov_sfs));
        } else {
                if (osfs->os_bsize != lov_sfs->os_bsize) {
                        /* assume all block sizes are always powers of 2 */
                        /* get the bits difference */
                        tmp = osfs->os_bsize | lov_sfs->os_bsize;
                        for (shift = 0; shift <= 64; ++shift) {
                                if (tmp & 1) {
                                        if (quit)
                                                break;
                                        else
                                                quit = 1;
                                        shift = 0;
                                }
                                tmp >>= 1;
                        }
                }

                if (osfs->os_bsize < lov_sfs->os_bsize) {
                        osfs->os_bsize = lov_sfs->os_bsize;

                        osfs->os_bfree  >>= shift;
                        osfs->os_bavail >>= shift;
                        osfs->os_blocks >>= shift;
                } else if (shift != 0) {
                        lov_sfs->os_bfree  >>= shift;
                        lov_sfs->os_bavail >>= shift;
                        lov_sfs->os_blocks >>= shift;
                }
#ifdef MIN_DF
                /* Sandia requested that df (and so, statfs) only
                   returned minimal available space on
                   a single OST, so people would be able to
                   write this much data guaranteed. */
                if (osfs->os_bavail > lov_sfs->os_bavail) {
                        /* Presumably if new bavail is smaller,
                           new bfree is bigger as well */
                        osfs->os_bfree = lov_sfs->os_bfree;
                        osfs->os_bavail = lov_sfs->os_bavail;
                }
#else
                osfs->os_bfree += lov_sfs->os_bfree;
                osfs->os_bavail += lov_sfs->os_bavail;
#endif
                osfs->os_blocks += lov_sfs->os_blocks;
                /* XXX not sure about this one - depends on policy.
                 *   - could be minimum if we always stripe on all OBDs
                 *     (but that would be wrong for any other policy,
                 *     if one of the OBDs has no more objects left)
                 *   - could be sum if we stripe whole objects
                 *   - could be average, just to give a nice number
                 *
                 * To give a "reasonable" (if not wholly accurate)
                 * number, we divide the total number of free objects
                 * by expected stripe count (watch out for overflow).
                 */
                LOV_SUM_MAX(osfs->os_files, lov_sfs->os_files);
                LOV_SUM_MAX(osfs->os_ffree, lov_sfs->os_ffree);
        }
}

/* The callback for osc_statfs_async that finilizes a request info when a
 * response is received. */
static int cb_statfs_update(void *cookie, int rc)
{
        struct obd_info *oinfo = cookie;
        struct lov_request *lovreq;
        struct lov_request_set *set;
        struct obd_statfs *osfs, *lov_sfs;
        struct lov_obd *lov;
        struct lov_tgt_desc *tgt;
        struct obd_device *lovobd, *tgtobd;
        int success;
        ENTRY;

	lovreq = container_of(oinfo, struct lov_request, rq_oi);
	set = lovreq->rq_rqset;
	lovobd = set->set_obd;
	lov = &lovobd->u.lov;
	osfs = set->set_oi->oi_osfs;
	lov_sfs = oinfo->oi_osfs;
	success = atomic_read(&set->set_success);
	/* XXX: the same is done in lov_update_common_set, however
	   lovset->set_exp is not initialized. */
	lov_update_set(set, lovreq, rc);
	if (rc)
		GOTO(out, rc);

        obd_getref(lovobd);
        tgt = lov->lov_tgts[lovreq->rq_idx];
        if (!tgt || !tgt->ltd_active)
                GOTO(out_update, rc);

        tgtobd = class_exp2obd(tgt->ltd_exp);
	spin_lock(&tgtobd->obd_osfs_lock);
	memcpy(&tgtobd->obd_osfs, lov_sfs, sizeof(*lov_sfs));
	if ((oinfo->oi_flags & OBD_STATFS_FROM_CACHE) == 0)
		tgtobd->obd_osfs_age = cfs_time_current_64();
	spin_unlock(&tgtobd->obd_osfs_lock);

out_update:
        lov_update_statfs(osfs, lov_sfs, success);
        obd_putref(lovobd);

out:
	RETURN(0);
}

int lov_prep_statfs_set(struct obd_device *obd, struct obd_info *oinfo,
                        struct lov_request_set **reqset)
{
        struct lov_request_set *set;
        struct lov_obd *lov = &obd->u.lov;
        int rc = 0, i;
        ENTRY;

        OBD_ALLOC(set, sizeof(*set));
        if (set == NULL)
                RETURN(-ENOMEM);
        lov_init_set(set);

        set->set_obd = obd;
        set->set_oi = oinfo;

        /* We only get block data from the OBD */
        for (i = 0; i < lov->desc.ld_tgt_count; i++) {
		struct lov_request *req;

		if (lov->lov_tgts[i] == NULL ||
		    (oinfo->oi_flags & OBD_STATFS_NODELAY &&
		     !lov->lov_tgts[i]->ltd_active)) {
			CDEBUG(D_HA, "lov idx %d inactive\n", i);
			continue;
		}

		/* skip targets that have been explicitely disabled by the
		 * administrator */
		if (!lov->lov_tgts[i]->ltd_exp) {
			CDEBUG(D_HA, "lov idx %d administratively disabled\n",
			       i);
			continue;
		}

		if (!lov->lov_tgts[i]->ltd_active)
			lov_check_and_wait_active(lov, i);

		OBD_ALLOC(req, sizeof(*req));
		if (req == NULL)
			GOTO(out_set, rc = -ENOMEM);

                OBD_ALLOC(req->rq_oi.oi_osfs, sizeof(*req->rq_oi.oi_osfs));
                if (req->rq_oi.oi_osfs == NULL) {
                        OBD_FREE(req, sizeof(*req));
                        GOTO(out_set, rc = -ENOMEM);
                }

                req->rq_idx = i;
                req->rq_oi.oi_cb_up = cb_statfs_update;
                req->rq_oi.oi_flags = oinfo->oi_flags;

                lov_set_add_req(req, set);
        }
        if (!set->set_count)
                GOTO(out_set, rc = -EIO);
        *reqset = set;
        RETURN(rc);
out_set:
        lov_fini_statfs_set(set);
        RETURN(rc);
}