/*        $NetBSD: dm_table.c,v 1.21 2021/08/21 22:23:33 andvar Exp $      */

/*
* 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/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: dm_table.c,v 1.21 2021/08/21 22:23:33 andvar Exp $");

#include <sys/types.h>
#include <sys/param.h>
#include <sys/kmem.h>

#include "dm.h"

/*
* There are two types of users of this interface:
*
* a) Readers such as
*    dmstrategy, dmgetdisklabel, dmsize, dm_dev_status_ioctl,
*    dm_table_deps_ioctl, dm_table_status_ioctl, dm_table_reload_ioctl
*
* b) Writers such as
*    dm_dev_remove_ioctl, dm_dev_resume_ioctl, dm_table_clear_ioctl
*
* Writers can work with table_head only when there are no readers. I
* use reference counting on io_cnt.
*
*/

static int dm_table_busy(dm_table_head_t *, uint8_t);
static void dm_table_unbusy(dm_table_head_t *);
static void dm_table_free_deps(dm_table_entry_t *);


/*
* Function to increment table user reference counter. Return id
* of table_id table.
* DM_TABLE_ACTIVE will return active table id.
* DM_TABLE_INACTIVE will return inactive table id.
*/
static int
dm_table_busy(dm_table_head_t *head, uint8_t table_id)
{
       uint8_t id;

       mutex_enter(&head->table_mtx);

       if (table_id == DM_TABLE_ACTIVE)
               id = head->cur_active_table;
       else
               id = 1 - head->cur_active_table;

       head->io_cnt++;

       mutex_exit(&head->table_mtx);
       return id;
}

/*
* Function release table lock and eventually wakeup all waiters.
*/
static void
dm_table_unbusy(dm_table_head_t *head)
{

       KASSERT(head->io_cnt != 0);

       mutex_enter(&head->table_mtx);

       if (--head->io_cnt == 0)
               cv_broadcast(&head->table_cv);

       mutex_exit(&head->table_mtx);
}

/*
* Return current active table to caller, increment io_cnt reference counter.
*/
dm_table_t *
dm_table_get_entry(dm_table_head_t *head, uint8_t table_id)
{
       uint8_t id;

       id = dm_table_busy(head, table_id);

       return &head->tables[id];
}
/*
* Decrement io reference counter and wake up all callers, with table_head cv.
*/
void
dm_table_release(dm_table_head_t *head, uint8_t table_id)
{

       dm_table_unbusy(head);
}

/*
* Switch table from inactive to active mode. Have to wait until io_cnt is 0.
*/
void
dm_table_switch_tables(dm_table_head_t *head)
{

       mutex_enter(&head->table_mtx);

       while (head->io_cnt != 0)
               cv_wait(&head->table_cv, &head->table_mtx);

       head->cur_active_table = 1 - head->cur_active_table;

       mutex_exit(&head->table_mtx);
}

/*
* Destroy all table data. This function can run when there are no
* readers on table lists.
*
* XXX Is it ok to call kmem_free and potentially VOP_CLOSE with held mutex ?xs
*/
int
dm_table_destroy(dm_table_head_t *head, uint8_t table_id)
{
       dm_table_t *tbl;
       dm_table_entry_t *table_en;
       uint8_t id;

       mutex_enter(&head->table_mtx);

       aprint_debug("dm_Table_destroy called with %d--%d\n", table_id, head->io_cnt);

       while (head->io_cnt != 0)
               cv_wait(&head->table_cv, &head->table_mtx);

       if (table_id == DM_TABLE_ACTIVE)
               id = head->cur_active_table;
       else
               id = 1 - head->cur_active_table;

       tbl = &head->tables[id];

       while ((table_en = SLIST_FIRST(tbl)) != NULL) {
               SLIST_REMOVE(tbl, table_en, dm_table_entry, next);
               if (table_en->target->destroy(table_en) == 0)
                       table_en->target_config = NULL;
               dm_table_free_deps(table_en);
               kmem_free(table_en, sizeof(*table_en));
       }
       KASSERT(SLIST_EMPTY(tbl));

       mutex_exit(&head->table_mtx);

       return 0;
}

/*
* Return length of active table in device.
*/
static uint64_t
dm_table_size_impl(dm_table_head_t *head, int table)
{
       dm_table_t *tbl;
       dm_table_entry_t *table_en;
       uint64_t length;
       uint8_t id;

       length = 0;

       id = dm_table_busy(head, table);

       /* Select active table */
       tbl = &head->tables[id];

       /*
        * Find out what tables I want to select.
        * if length => rawblkno then we should used that table.
        */
       SLIST_FOREACH(table_en, tbl, next)
               length += table_en->length;

       dm_table_unbusy(head);

       return length;
}

/*
* Return length of active table in device.
*/
uint64_t
dm_table_size(dm_table_head_t *head)
{

       return dm_table_size_impl(head, DM_TABLE_ACTIVE);
}

/*
* Return length of active table in device.
*/
uint64_t
dm_inactive_table_size(dm_table_head_t *head)
{

       return dm_table_size_impl(head, DM_TABLE_INACTIVE);
}

/*
* Return combined disk geometry
*/
void
dm_table_disksize(dm_table_head_t *head, uint64_t *numsecp,
   unsigned int *secsizep)
{
       dm_table_t *tbl;
       dm_table_entry_t *table_en;
       uint64_t length;
       unsigned int secsize, tsecsize;
       uint8_t id;

       length = 0;

       id = dm_table_busy(head, DM_TABLE_ACTIVE);

       /* Select active table */
       tbl = &head->tables[id];

       /*
        * Find out what tables I want to select.
        * if length => rawblkno then we should used that table.
        */
       secsize = 0;
       SLIST_FOREACH(table_en, tbl, next) {
               length += table_en->length;
               if (table_en->target->secsize)
                       table_en->target->secsize(table_en, &tsecsize);
               else
                       tsecsize = 0;
               if (secsize < tsecsize)
                       secsize = tsecsize;
       }

       if (numsecp)
               *numsecp = secsize > 0 ? dbtob(length) / secsize : 0;
       if (secsizep)
               *secsizep = secsize;

       dm_table_unbusy(head);
}

/*
* Return > 0 if table is at least one table entry (returns number of entries)
* and return 0 if there is not. Target count returned from this function
* doesn't need to be true when userspace user receives it (after return
* there can be dm_dev_resume_ioctl), therefore this is only informative.
*/
int
dm_table_get_target_count(dm_table_head_t *head, uint8_t table_id)
{
       dm_table_entry_t *table_en;
       dm_table_t *tbl;
       uint32_t target_count;
       uint8_t id;

       target_count = 0;

       id = dm_table_busy(head, table_id);
       tbl = &head->tables[id];

       SLIST_FOREACH(table_en, tbl, next)
               target_count++;

       dm_table_unbusy(head);

       return target_count;
}

/*
* Initialize table_head structures, I'm trying to keep this structure as
* opaque as possible.
*/
void
dm_table_head_init(dm_table_head_t *head)
{

       head->cur_active_table = 0;
       head->io_cnt = 0;

       /* Initialize tables. */
       SLIST_INIT(&head->tables[0]);
       SLIST_INIT(&head->tables[1]);

       mutex_init(&head->table_mtx, MUTEX_DEFAULT, IPL_NONE);
       cv_init(&head->table_cv, "dm_io");
}

/*
* Destroy all variables in table_head
*/
void
dm_table_head_destroy(dm_table_head_t *head)
{

       KASSERT(!mutex_owned(&head->table_mtx));
       KASSERT(!cv_has_waiters(&head->table_cv));
       /* tables don't exist when I call this routine, therefore it
        * doesn't make sense to have io_cnt != 0 */
       KASSERT(head->io_cnt == 0);

       cv_destroy(&head->table_cv);
       mutex_destroy(&head->table_mtx);
}

int
dm_table_add_deps(dm_table_entry_t *table_en, dm_pdev_t *pdev)
{
       dm_table_head_t *head;
       dm_mapping_t *map;

       if (!pdev)
               return -1;

       head = &table_en->dm_dev->table_head;
       mutex_enter(&head->table_mtx);

       TAILQ_FOREACH(map, &table_en->pdev_maps, next) {
               if (map->data.pdev->pdev_vnode->v_rdev ==
                   pdev->pdev_vnode->v_rdev) {
                       mutex_exit(&head->table_mtx);
                       return -1;
               }
       }

       map = kmem_alloc(sizeof(*map), KM_SLEEP);
       map->data.pdev = pdev;
       aprint_debug("%s: %s\n", __func__, pdev->name);
       TAILQ_INSERT_TAIL(&table_en->pdev_maps, map, next);

       mutex_exit(&head->table_mtx);

       return 0;
}

/* caller must hold ->table_mtx */
static void
dm_table_free_deps(dm_table_entry_t *table_en)
{
       dm_mapping_t *map;

       while ((map = TAILQ_FIRST(&table_en->pdev_maps)) != NULL) {
               TAILQ_REMOVE(&table_en->pdev_maps, map, next);
               aprint_debug("%s: %s\n", __func__, map->data.pdev->name);
               kmem_free(map, sizeof(*map));
       }
       KASSERT(TAILQ_EMPTY(&table_en->pdev_maps));
}

You are viewing proxied material from ftp.icm.edu.pl. The copyright of proxied material belongs to its original authors. Any comments or complaints in relation to proxied material should be directed to the original authors of the content concerned. Please see the disclaimer for more details.