/*
 * 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://http://www.gnu.org/licenses/gpl-2.0.html
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * lustre/lov/lov_pool.c
 *
 * OST pool methods
 *
 * Author: Jacques-Charles LAFOUCRIERE <jc.lafoucriere@cea.fr>
 * Author: Alex Lyashkov <Alexey.Lyashkov@Sun.COM>
 * Author: Nathaniel Rutman <Nathan.Rutman@Sun.COM>
 */

#define DEBUG_SUBSYSTEM S_LOV

#include <linux/libcfs/libcfs.h>

#include <obd.h>
#include "lov_internal.h"

#define pool_tgt(_p, _i) \
                _p->pool_lobd->u.lov.lov_tgts[_p->pool_obds.op_array[_i]]

static void lov_pool_getref(struct pool_desc *pool)
{
        CDEBUG(D_INFO, "pool %p\n", pool);
        atomic_inc(&pool->pool_refcount);
}

void lov_pool_putref(struct pool_desc *pool)
{
        CDEBUG(D_INFO, "pool %p\n", pool);
        if (atomic_dec_and_test(&pool->pool_refcount)) {
                LASSERT(hlist_unhashed(&pool->pool_hash));
                LASSERT(list_empty(&pool->pool_list));
                LASSERT(!pool->pool_debugfs_entry);
                lov_ost_pool_free(&pool->pool_obds);
                kfree(pool);
        }
}

static void lov_pool_putref_locked(struct pool_desc *pool)
{
        CDEBUG(D_INFO, "pool %p\n", pool);
        LASSERT(atomic_read(&pool->pool_refcount) > 1);

        atomic_dec(&pool->pool_refcount);
}

/*
 * hash function using a Rotating Hash algorithm
 * Knuth, D. The Art of Computer Programming,
 * Volume 3: Sorting and Searching,
 * Chapter 6.4.
 * Addison Wesley, 1973
 */
static __u32 pool_hashfn(struct cfs_hash *hash_body, const void *key,
                         unsigned int mask)
{
        int i;
        __u32 result;
        char *poolname;

        result = 0;
        poolname = (char *)key;
        for (i = 0; i < LOV_MAXPOOLNAME; i++) {
                if (poolname[i] == '\0')
                        break;
                result = (result << 4) ^ (result >> 28) ^  poolname[i];
        }
        return (result % mask);
}

static void *pool_key(struct hlist_node *hnode)
{
        struct pool_desc *pool;

        pool = hlist_entry(hnode, struct pool_desc, pool_hash);
        return pool->pool_name;
}

static int pool_hashkey_keycmp(const void *key, struct hlist_node *compared_hnode)
{
        char *pool_name;
        struct pool_desc *pool;

        pool_name = (char *)key;
        pool = hlist_entry(compared_hnode, struct pool_desc, pool_hash);
        return !strncmp(pool_name, pool->pool_name, LOV_MAXPOOLNAME);
}

static void *pool_hashobject(struct hlist_node *hnode)
{
        return hlist_entry(hnode, struct pool_desc, pool_hash);
}

static void pool_hashrefcount_get(struct cfs_hash *hs, struct hlist_node *hnode)
{
        struct pool_desc *pool;

        pool = hlist_entry(hnode, struct pool_desc, pool_hash);
        lov_pool_getref(pool);
}

static void pool_hashrefcount_put_locked(struct cfs_hash *hs,
                                         struct hlist_node *hnode)
{
        struct pool_desc *pool;

        pool = hlist_entry(hnode, struct pool_desc, pool_hash);
        lov_pool_putref_locked(pool);
}

struct cfs_hash_ops pool_hash_operations = {
        .hs_hash        = pool_hashfn,
        .hs_key         = pool_key,
        .hs_keycmp      = pool_hashkey_keycmp,
        .hs_object      = pool_hashobject,
        .hs_get         = pool_hashrefcount_get,
        .hs_put_locked  = pool_hashrefcount_put_locked,

};

/*
 * pool debugfs seq_file methods
 */
/*
 * iterator is used to go through the target pool entries
 * index is the current entry index in the lp_array[] array
 * index >= pos returned to the seq_file interface
 * pos is from 0 to (pool->pool_obds.op_count - 1)
 */
#define POOL_IT_MAGIC 0xB001CEA0
struct pool_iterator {
        int magic;
        struct pool_desc *pool;
        int idx;        /* from 0 to pool_tgt_size - 1 */
};

static void *pool_proc_next(struct seq_file *s, void *v, loff_t *pos)
{
        struct pool_iterator *iter = (struct pool_iterator *)s->private;
        int prev_idx;

        LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X\n", iter->magic);

        /* test if end of file */
        if (*pos >= pool_tgt_count(iter->pool))
                return NULL;

        /* iterate to find a non empty entry */
        prev_idx = iter->idx;
        down_read(&pool_tgt_rw_sem(iter->pool));
        iter->idx++;
        if (iter->idx == pool_tgt_count(iter->pool)) {
                iter->idx = prev_idx; /* we stay on the last entry */
                up_read(&pool_tgt_rw_sem(iter->pool));
                return NULL;
        }
        up_read(&pool_tgt_rw_sem(iter->pool));
        (*pos)++;
        /* return != NULL to continue */
        return iter;
}

static void *pool_proc_start(struct seq_file *s, loff_t *pos)
{
        struct pool_desc *pool = (struct pool_desc *)s->private;
        struct pool_iterator *iter;

        lov_pool_getref(pool);
        if ((pool_tgt_count(pool) == 0) ||
            (*pos >= pool_tgt_count(pool))) {
                /* iter is not created, so stop() has no way to
                 * find pool to dec ref
                 */
                lov_pool_putref(pool);
                return NULL;
        }

        iter = kzalloc(sizeof(*iter), GFP_NOFS);
        if (!iter)
                return ERR_PTR(-ENOMEM);
        iter->magic = POOL_IT_MAGIC;
        iter->pool = pool;
        iter->idx = 0;

        /* we use seq_file private field to memorized iterator so
         * we can free it at stop()
         */
        /* /!\ do not forget to restore it to pool before freeing it */
        s->private = iter;
        if (*pos > 0) {
                loff_t i;
                void *ptr;

                i = 0;
                do {
                        ptr = pool_proc_next(s, &iter, &i);
                } while ((i < *pos) && ptr);
                return ptr;
        }
        return iter;
}

static void pool_proc_stop(struct seq_file *s, void *v)
{
        struct pool_iterator *iter = (struct pool_iterator *)s->private;

        /* in some cases stop() method is called 2 times, without
         * calling start() method (see seq_read() from fs/seq_file.c)
         * we have to free only if s->private is an iterator
         */
        if ((iter) && (iter->magic == POOL_IT_MAGIC)) {
                /* we restore s->private so next call to pool_proc_start()
                 * will work
                 */
                s->private = iter->pool;
                lov_pool_putref(iter->pool);
                kfree(iter);
        }
}

static int pool_proc_show(struct seq_file *s, void *v)
{
        struct pool_iterator *iter = (struct pool_iterator *)v;
        struct lov_tgt_desc *tgt;

        LASSERTF(iter->magic == POOL_IT_MAGIC, "%08X\n", iter->magic);
        LASSERT(iter->pool);
        LASSERT(iter->idx <= pool_tgt_count(iter->pool));

        down_read(&pool_tgt_rw_sem(iter->pool));
        tgt = pool_tgt(iter->pool, iter->idx);
        up_read(&pool_tgt_rw_sem(iter->pool));
        if (tgt)
                seq_printf(s, "%s\n", obd_uuid2str(&tgt->ltd_uuid));

        return 0;
}

static const struct seq_operations pool_proc_ops = {
        .start    = pool_proc_start,
        .next      = pool_proc_next,
        .stop      = pool_proc_stop,
        .show      = pool_proc_show,
};

static int pool_proc_open(struct inode *inode, struct file *file)
{
        int rc;

        rc = seq_open(file, &pool_proc_ops);
        if (!rc) {
                struct seq_file *s = file->private_data;

                s->private = inode->i_private;
        }
        return rc;
}

static const struct file_operations pool_proc_operations = {
        .open      = pool_proc_open,
        .read      = seq_read,
        .llseek  = seq_lseek,
        .release        = seq_release,
};

#define LOV_POOL_INIT_COUNT 2
int lov_ost_pool_init(struct ost_pool *op, unsigned int count)
{
        if (count == 0)
                count = LOV_POOL_INIT_COUNT;
        op->op_array = NULL;
        op->op_count = 0;
        init_rwsem(&op->op_rw_sem);
        op->op_size = count;
        op->op_array = kcalloc(op->op_size, sizeof(op->op_array[0]), GFP_NOFS);
        if (!op->op_array) {
                op->op_size = 0;
                return -ENOMEM;
        }
        return 0;
}

/* Caller must hold write op_rwlock */
int lov_ost_pool_extend(struct ost_pool *op, unsigned int min_count)
{
        __u32 *new;
        int new_size;

        LASSERT(min_count != 0);

        if (op->op_count < op->op_size)
                return 0;

        new_size = max(min_count, 2 * op->op_size);
        new = kcalloc(new_size, sizeof(op->op_array[0]), GFP_NOFS);
        if (!new)
                return -ENOMEM;

        /* copy old array to new one */
        memcpy(new, op->op_array, op->op_size * sizeof(op->op_array[0]));
        kfree(op->op_array);
        op->op_array = new;
        op->op_size = new_size;
        return 0;
}

int lov_ost_pool_add(struct ost_pool *op, __u32 idx, unsigned int min_count)
{
        int rc = 0, i;

        down_write(&op->op_rw_sem);

        rc = lov_ost_pool_extend(op, min_count);
        if (rc)
                goto out;

        /* search ost in pool array */
        for (i = 0; i < op->op_count; i++) {
                if (op->op_array[i] == idx) {
                        rc = -EEXIST;
                        goto out;
                }
        }
        /* ost not found we add it */
        op->op_array[op->op_count] = idx;
        op->op_count++;
out:
        up_write(&op->op_rw_sem);
        return rc;
}

int lov_ost_pool_remove(struct ost_pool *op, __u32 idx)
{
        int i;

        down_write(&op->op_rw_sem);

        for (i = 0; i < op->op_count; i++) {
                if (op->op_array[i] == idx) {
                        memmove(&op->op_array[i], &op->op_array[i + 1],
                                (op->op_count - i - 1) * sizeof(op->op_array[0]));
                        op->op_count--;
                        up_write(&op->op_rw_sem);
                        return 0;
                }
        }

        up_write(&op->op_rw_sem);
        return -EINVAL;
}

int lov_ost_pool_free(struct ost_pool *op)
{
        if (op->op_size == 0)
                return 0;

        down_write(&op->op_rw_sem);

        kfree(op->op_array);
        op->op_array = NULL;
        op->op_count = 0;
        op->op_size = 0;

        up_write(&op->op_rw_sem);
        return 0;
}

int lov_pool_new(struct obd_device *obd, char *poolname)
{
        struct lov_obd *lov;
        struct pool_desc *new_pool;
        int rc;

        lov = &obd->u.lov;

        if (strlen(poolname) > LOV_MAXPOOLNAME)
                return -ENAMETOOLONG;

        new_pool = kzalloc(sizeof(*new_pool), GFP_NOFS);
        if (!new_pool)
                return -ENOMEM;

        strlcpy(new_pool->pool_name, poolname, sizeof(new_pool->pool_name));
        new_pool->pool_lobd = obd;
        /* ref count init to 1 because when created a pool is always used
         * up to deletion
         */
        atomic_set(&new_pool->pool_refcount, 1);
        rc = lov_ost_pool_init(&new_pool->pool_obds, 0);
        if (rc)
                goto out_err;

        INIT_HLIST_NODE(&new_pool->pool_hash);

        /* get ref for debugfs file */
        lov_pool_getref(new_pool);
        new_pool->pool_debugfs_entry = ldebugfs_add_simple(
                                                lov->lov_pool_debugfs_entry,
                                                poolname, new_pool,
                                                &pool_proc_operations);
        if (IS_ERR_OR_NULL(new_pool->pool_debugfs_entry)) {
                CWARN("Cannot add debugfs pool entry " LOV_POOLNAMEF "\n",
                      poolname);
                new_pool->pool_debugfs_entry = NULL;
                lov_pool_putref(new_pool);
        }
        CDEBUG(D_INFO, "pool %p - proc %p\n",
               new_pool, new_pool->pool_debugfs_entry);

        spin_lock(&obd->obd_dev_lock);
        list_add_tail(&new_pool->pool_list, &lov->lov_pool_list);
        lov->lov_pool_count++;
        spin_unlock(&obd->obd_dev_lock);

        /* add to find only when it fully ready  */
        rc = cfs_hash_add_unique(lov->lov_pools_hash_body, poolname,
                                 &new_pool->pool_hash);
        if (rc) {
                rc = -EEXIST;
                goto out_err;
        }

        CDEBUG(D_CONFIG, LOV_POOLNAMEF " is pool #%d\n",
               poolname, lov->lov_pool_count);

        return 0;

out_err:
        spin_lock(&obd->obd_dev_lock);
        list_del_init(&new_pool->pool_list);
        lov->lov_pool_count--;
        spin_unlock(&obd->obd_dev_lock);
        ldebugfs_remove(&new_pool->pool_debugfs_entry);
        lov_ost_pool_free(&new_pool->pool_obds);
        kfree(new_pool);

        return rc;
}

int lov_pool_del(struct obd_device *obd, char *poolname)
{
        struct lov_obd *lov;
        struct pool_desc *pool;

        lov = &obd->u.lov;

        /* lookup and kill hash reference */
        pool = cfs_hash_del_key(lov->lov_pools_hash_body, poolname);
        if (!pool)
                return -ENOENT;

        if (!IS_ERR_OR_NULL(pool->pool_debugfs_entry)) {
                CDEBUG(D_INFO, "proc entry %p\n", pool->pool_debugfs_entry);
                ldebugfs_remove(&pool->pool_debugfs_entry);
                lov_pool_putref(pool);
        }

        spin_lock(&obd->obd_dev_lock);
        list_del_init(&pool->pool_list);
        lov->lov_pool_count--;
        spin_unlock(&obd->obd_dev_lock);

        /* release last reference */
        lov_pool_putref(pool);

        return 0;
}

int lov_pool_add(struct obd_device *obd, char *poolname, char *ostname)
{
        struct obd_uuid ost_uuid;
        struct lov_obd *lov;
        struct pool_desc *pool;
        unsigned int lov_idx;
        int rc;

        lov = &obd->u.lov;

        pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
        if (!pool)
                return -ENOENT;

        obd_str2uuid(&ost_uuid, ostname);

        /* search ost in lov array */
        obd_getref(obd);
        for (lov_idx = 0; lov_idx < lov->desc.ld_tgt_count; lov_idx++) {
                if (!lov->lov_tgts[lov_idx])
                        continue;
                if (obd_uuid_equals(&ost_uuid,
                                    &lov->lov_tgts[lov_idx]->ltd_uuid))
                        break;
        }
        /* test if ost found in lov */
        if (lov_idx == lov->desc.ld_tgt_count) {
                rc = -EINVAL;
                goto out;
        }

        rc = lov_ost_pool_add(&pool->pool_obds, lov_idx, lov->lov_tgt_size);
        if (rc)
                goto out;

        CDEBUG(D_CONFIG, "Added %s to " LOV_POOLNAMEF " as member %d\n",
               ostname, poolname,  pool_tgt_count(pool));

out:
        obd_putref(obd);
        lov_pool_putref(pool);
        return rc;
}

int lov_pool_remove(struct obd_device *obd, char *poolname, char *ostname)
{
        struct obd_uuid ost_uuid;
        struct lov_obd *lov;
        struct pool_desc *pool;
        unsigned int lov_idx;
        int rc = 0;

        lov = &obd->u.lov;

        pool = cfs_hash_lookup(lov->lov_pools_hash_body, poolname);
        if (!pool)
                return -ENOENT;

        obd_str2uuid(&ost_uuid, ostname);

        obd_getref(obd);
        /* search ost in lov array, to get index */
        for (lov_idx = 0; lov_idx < lov->desc.ld_tgt_count; lov_idx++) {
                if (!lov->lov_tgts[lov_idx])
                        continue;

                if (obd_uuid_equals(&ost_uuid,
                                    &lov->lov_tgts[lov_idx]->ltd_uuid))
                        break;
        }

        /* test if ost found in lov */
        if (lov_idx == lov->desc.ld_tgt_count) {
                rc = -EINVAL;
                goto out;
        }

        lov_ost_pool_remove(&pool->pool_obds, lov_idx);

        CDEBUG(D_CONFIG, "%s removed from " LOV_POOLNAMEF "\n", ostname,
               poolname);

out:
        obd_putref(obd);
        lov_pool_putref(pool);
        return rc;
}