/*        $NetBSD: dm_dev.c,v 1.8 2010/01/04 00:19:08 haad Exp $      */

/*
 * Copyright (c) 2010-2011 Alex Hornung <alex@alexhornung.com>
 * Copyright (c) 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Adam Hamsik.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/disk.h>
#include <sys/disklabel.h>
#include <sys/devicestat.h>
#include <sys/device.h>
#include <sys/udev.h>
#include <sys/devfs.h>
#include <sys/malloc.h>
#include <machine/thread.h>
#include <dev/disk/dm/dm.h>
#include <dev/disk/dm/netbsd-dm.h>

extern struct dev_ops dm_ops;

static struct devfs_bitmap dm_minor_bitmap;
uint64_t dm_dev_counter;

static dm_dev_t *dm_dev_lookup_name(const char *);
static dm_dev_t *dm_dev_lookup_uuid(const char *);
static dm_dev_t *dm_dev_lookup_minor(int);
static int dm_dev_destroy(dm_dev_t *);
static dm_dev_t *dm_dev_alloc(const char *, const char *);
static int dm_dev_free(dm_dev_t *);

static TAILQ_HEAD(dm_dev_head, dm_dev) dm_dev_list;

static struct lock dm_dev_mutex;

static char dummy_uuid[DM_UUID_LEN];

/*
 * dm_dev_mutex must be held by caller before using disable_dev.
 */
static void
disable_dev(dm_dev_t *dmv)
{
        KKASSERT(lockstatus(&dm_dev_mutex, curthread) == LK_EXCLUSIVE);

        TAILQ_REMOVE(&dm_dev_list, dmv, next_devlist);
        dm_dev_counter--;

        lockmgr(&dmv->dev_mtx, LK_EXCLUSIVE);
        while (dmv->ref_cnt != 0)
                cv_wait(&dmv->dev_cv, &dmv->dev_mtx);
        lockmgr(&dmv->dev_mtx, LK_RELEASE);
}

static dm_dev_t *
_dm_dev_lookup(const char *name, const char *uuid, int minor)
{
        dm_dev_t *dmv;

        if (minor > 0) {
                if ((dmv = dm_dev_lookup_minor(minor)))
                        return dmv;
        }
        if (name != NULL) {
                if ((dmv = dm_dev_lookup_name(name)))
                        return dmv;
        }
        if (uuid != NULL) {
                if ((dmv = dm_dev_lookup_uuid(uuid)))
                        return dmv;
        }

        return NULL;
}

/*
 * Generic function used to lookup dm_dev_t. Calling with name NULL
 * and uuid NULL is allowed.
 */
dm_dev_t *
dm_dev_lookup(const char *name, const char *uuid, int minor)
{
        dm_dev_t *dmv;

        lockmgr(&dm_dev_mutex, LK_EXCLUSIVE);

        dmv = _dm_dev_lookup(name, uuid, minor);
        if (dmv)
                dm_dev_busy(dmv);

        lockmgr(&dm_dev_mutex, LK_RELEASE);

        return dmv;
}


/*
 * Lookup device with its minor number.
 */
static dm_dev_t *
dm_dev_lookup_minor(int dm_dev_minor)
{
        dm_dev_t *dmv;

        TAILQ_FOREACH(dmv, &dm_dev_list, next_devlist) {
                if (dm_dev_minor == dmv->minor)
                        return dmv;
        }

        return NULL;
}

/*
 * Lookup device with it's device name.
 */
static dm_dev_t *
dm_dev_lookup_name(const char *dm_dev_name)
{
        dm_dev_t *dmv;

        TAILQ_FOREACH(dmv, &dm_dev_list, next_devlist) {
                if (strcmp(dm_dev_name, dmv->name) == 0)
                        return dmv;
        }

        return NULL;
}

/*
 * Lookup device with it's device uuid. Used mostly by LVM2tools.
 */
static dm_dev_t *
dm_dev_lookup_uuid(const char *dm_dev_uuid)
{
        dm_dev_t *dmv;

        TAILQ_FOREACH(dmv, &dm_dev_list, next_devlist) {
                if (strcmp(dm_dev_uuid, dmv->uuid) == 0)
                        return dmv;
        }

        return NULL;
}

/*
 * Insert new device to the global list of devices.
 */
int
dm_dev_insert(dm_dev_t *dev)
{
        dm_dev_t *dmv;
        int r;

        dmv = NULL;
        r = 0;

        KKASSERT(dev != NULL);
        lockmgr(&dm_dev_mutex, LK_EXCLUSIVE);

        /*
         * Ignore uuid lookup if dev->uuid is zero-filled.
         */
        if (memcmp(dev->uuid, dummy_uuid, DM_UUID_LEN))
                dmv = dm_dev_lookup_uuid(dev->uuid);

        if ((dmv == NULL) &&
            (_dm_dev_lookup(dev->name, NULL, dev->minor) == NULL)) {
                TAILQ_INSERT_TAIL(&dm_dev_list, dev, next_devlist);
                dm_dev_counter++;
        } else {
                KKASSERT(dmv != NULL);
                r = EEXIST;
        }

        lockmgr(&dm_dev_mutex, LK_RELEASE);
        return r;
}

#if 0
/*
 * Remove device selected with dm_dev from global list of devices.
 */
dm_dev_t *
dm_dev_lookup_evict(const char *name, const char *uuid, int minor)
{
        dm_dev_t *dmv;

        lockmgr(&dm_dev_mutex, LK_EXCLUSIVE);

        dmv = _dm_dev_lookup(name, uuid, minor);
        if (dmv)
                disable_dev(dmv);

        lockmgr(&dm_dev_mutex, LK_RELEASE);

        return dmv;
}
#endif

int
dm_dev_create(dm_dev_t **dmvp, const char *name, const char *uuid, int flags)
{
        dm_dev_t *dmv;
        char name_buf[MAXPATHLEN];
        int r, dm_minor;

        if ((dmv = dm_dev_alloc(name, uuid)) == NULL)
                return ENOMEM;

        dm_minor = devfs_clone_bitmap_get(&dm_minor_bitmap, 0);

        dm_table_head_init(&dmv->table_head);

        lockinit(&dmv->dev_mtx, "dmdev", 0, LK_CANRECURSE);
        cv_init(&dmv->dev_cv, "dm_dev");

        if (flags & DM_READONLY_FLAG)
                dmv->flags |= DM_READONLY_FLAG;

        dmdebug("Creating device dm/%s\n", name);
        ksnprintf(name_buf, sizeof(name_buf), "mapper/%s", dmv->name);

        devstat_add_entry(&dmv->stats, name, 0, DEV_BSIZE,
            DEVSTAT_NO_ORDERED_TAGS,
            DEVSTAT_TYPE_DIRECT | DEVSTAT_TYPE_IF_OTHER,
            DEVSTAT_PRIORITY_DISK);

        dmv->devt = disk_create_named(name_buf, dm_minor, dmv->diskp, &dm_ops);
        reference_dev(dmv->devt);

        /* Make sure the device are immediately available */
        sync_devs();

        dmv->devt->si_drv1 = dmv;
        dmv->devt->si_drv2 = dmv->diskp;

        dmv->minor = minor(dmv->devt);
        udev_dict_set_cstr(dmv->devt, "subsystem", "disk");

        if ((r = dm_dev_insert(dmv)) != 0)
                dm_dev_destroy(dmv);

        *dmvp = dmv;

        return r;
}

static int
dm_dev_destroy(dm_dev_t *dmv)
{
        int minor;

        /* Destroy active table first.  */
        dm_table_destroy(&dmv->table_head, DM_TABLE_ACTIVE);

        /* Destroy inactive table if exits, too. */
        dm_table_destroy(&dmv->table_head, DM_TABLE_INACTIVE);

        dm_table_head_destroy(&dmv->table_head);

        minor = dkunit(dmv->devt);
        disk_destroy(dmv->diskp);
        devstat_remove_entry(&dmv->stats);

        release_dev(dmv->devt);
        devfs_clone_bitmap_put(&dm_minor_bitmap, minor);

        lockuninit(&dmv->dev_mtx);
        cv_destroy(&dmv->dev_cv);

        /* Destroy device */
        dm_dev_free(dmv);

        return 0;
}

/*
 * dm_dev_remove is called to completely destroy & remove a dm disk device.
 */
int
dm_dev_remove(dm_dev_t *dmv)
{
        /* Remove device from list and wait for refcnt to drop to zero */
        lockmgr(&dm_dev_mutex, LK_EXCLUSIVE);
        disable_dev(dmv);
        lockmgr(&dm_dev_mutex, LK_RELEASE);

        /* Destroy and free the device */
        dm_dev_destroy(dmv);

        return 0;
}

int
dm_dev_remove_all(int gentle)
{
        dm_dev_t *dmv, *dmv2;
        int r;

        r = 0;

        lockmgr(&dm_dev_mutex, LK_EXCLUSIVE);

        /*
         * Process in reverse order so that it can deal with inter-depentent
         * devices.
         */
        TAILQ_FOREACH_REVERSE_MUTABLE(dmv, &dm_dev_list, dm_dev_head,
            next_devlist, dmv2) {
                if (gentle && dmv->is_open) {
                        r = EBUSY;
                        continue;
                }

                disable_dev(dmv);
                dm_dev_destroy(dmv);
        }
        lockmgr(&dm_dev_mutex, LK_RELEASE);

        return r;
}

/*
 * Allocate new device entry.
 */
static dm_dev_t *
dm_dev_alloc(const char *name, const char*uuid)
{
        dm_dev_t *dmv;

        dmv = kmalloc(sizeof(*dmv), M_DM, M_WAITOK | M_ZERO);
        if (dmv == NULL)
                return NULL;

        dmv->diskp = kmalloc(sizeof(*dmv->diskp), M_DM, M_WAITOK | M_ZERO);
        if (dmv->diskp == NULL) {
                kfree(dmv, M_DM);
                return NULL;
        }

        if (name)
                strlcpy(dmv->name, name, sizeof(dmv->name));
        if (uuid)
                strncpy(dmv->uuid, uuid, sizeof(dmv->uuid));

        return dmv;
}

/*
 * Freed device entry.
 */
static int
dm_dev_free(dm_dev_t *dmv)
{
        KKASSERT(dmv != NULL);

        if (dmv->diskp != NULL)
                kfree(dmv->diskp, M_DM);

        kfree(dmv, M_DM);

        return 0;
}

void
dm_dev_busy(dm_dev_t *dmv)
{
        lockmgr(&dmv->dev_mtx, LK_EXCLUSIVE);
        dmv->ref_cnt++;
        lockmgr(&dmv->dev_mtx, LK_RELEASE);
}

void
dm_dev_unbusy(dm_dev_t *dmv)
{
        KKASSERT(dmv->ref_cnt != 0);

        lockmgr(&dmv->dev_mtx, LK_EXCLUSIVE);
        if (--dmv->ref_cnt == 0)
                cv_broadcast(&dmv->dev_cv);
        lockmgr(&dmv->dev_mtx, LK_RELEASE);
}

/*
 * Return prop_array of dm_targer_list dictionaries.
 */
prop_array_t
dm_dev_prop_list(void)
{
        dm_dev_t *dmv;
        prop_array_t dev_array;
        prop_dictionary_t dev_dict;

        dev_array = prop_array_create();

        lockmgr(&dm_dev_mutex, LK_EXCLUSIVE);

        TAILQ_FOREACH(dmv, &dm_dev_list, next_devlist) {
                dev_dict = prop_dictionary_create();

                prop_dictionary_set_cstring(dev_dict, DM_DEV_NAME, dmv->name);
                prop_dictionary_set_uint32(dev_dict, DM_DEV_DEV, dmv->minor);

                prop_array_add(dev_array, dev_dict);
                prop_object_release(dev_dict);
        }

        lockmgr(&dm_dev_mutex, LK_RELEASE);
        return dev_array;
}

/*
 * Initialize global device mutex.
 */
int
dm_dev_init(void)
{
        TAILQ_INIT(&dm_dev_list);       /* initialize global dev list */
        lockinit(&dm_dev_mutex, "dmdevlist", 0, LK_CANRECURSE);
        devfs_clone_bitmap_init(&dm_minor_bitmap);

        memset(dummy_uuid, 0, sizeof(dummy_uuid));
        return 0;
}

/*
 * Destroy all devices created in device-mapper. Remove all tables
 * free all allocated memmory.
 */
int
dm_dev_uninit(void)
{
        /* Force removal of all devices */
        dm_dev_remove_all(0);

        lockuninit(&dm_dev_mutex);
        return 0;
}