/*        $NetBSD: dm_pdev.c,v 1.23 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_pdev.c,v 1.23 2021/08/21 22:23:33 andvar Exp $");

#include <sys/types.h>
#include <sys/param.h>
#include <sys/disk.h>
#include <sys/fcntl.h>
#include <sys/kmem.h>
#include <sys/namei.h>

#include <dev/dkvar.h>

#include "dm.h"

static SLIST_HEAD(dm_pdevs, dm_pdev) dm_pdev_list;

static kmutex_t dm_pdev_mutex;

static dm_pdev_t *dm_pdev_alloc(const char *);
static int dm_pdev_rem(dm_pdev_t *);
static dm_pdev_t *dm_pdev_lookup_name(const char *);

/*
* Find used pdev with name == dm_pdev_name.
*/
dm_pdev_t *
dm_pdev_lookup_name(const char *dm_pdev_name)
{
       dm_pdev_t *dm_pdev;
       size_t dlen;
       size_t slen;

       KASSERT(dm_pdev_name != NULL);

       slen = strlen(dm_pdev_name);

       SLIST_FOREACH(dm_pdev, &dm_pdev_list, next_pdev) {
               dlen = strlen(dm_pdev->name);

               if (slen != dlen)
                       continue;

               if (strncmp(dm_pdev_name, dm_pdev->name, slen) == 0)
                       return dm_pdev;
       }

       return NULL;
}

/*
* Create entry for device with name dev_name and open vnode for it.
* If entry already exists in global SLIST I will only increment
* reference counter.
*/
dm_pdev_t *
dm_pdev_insert(const char *dev_name)
{
       struct pathbuf *dev_pb;
       dm_pdev_t *dmp;
       int error;

       KASSERT(dev_name != NULL);

       mutex_enter(&dm_pdev_mutex);
       dmp = dm_pdev_lookup_name(dev_name);

       if (dmp != NULL) {
               dmp->ref_cnt++;
               aprint_debug("%s: pdev %s already in tree\n",
                   __func__, dev_name);
               mutex_exit(&dm_pdev_mutex);
               return dmp;
       }

       if ((dmp = dm_pdev_alloc(dev_name)) == NULL) {
               mutex_exit(&dm_pdev_mutex);
               return NULL;
       }

       dev_pb = pathbuf_create(dev_name);
       if (dev_pb == NULL) {
               aprint_debug("%s: pathbuf_create on device: %s failed!\n",
                   __func__, dev_name);
               mutex_exit(&dm_pdev_mutex);
               kmem_free(dmp, sizeof(dm_pdev_t));
               return NULL;
       }
       error = vn_bdev_openpath(dev_pb, &dmp->pdev_vnode, curlwp);
       pathbuf_destroy(dev_pb);
       if (error) {
               aprint_debug("%s: lookup on device: %s (error %d)\n",
                   __func__, dev_name, error);
               mutex_exit(&dm_pdev_mutex);
               kmem_free(dmp, sizeof(dm_pdev_t));
               return NULL;
       }
       getdisksize(dmp->pdev_vnode, &dmp->pdev_numsec, &dmp->pdev_secsize);
       dmp->ref_cnt = 1;

       snprintf(dmp->udev_name, sizeof(dmp->udev_name), "%d:%d",
           major(dmp->pdev_vnode->v_rdev), minor(dmp->pdev_vnode->v_rdev));
       aprint_debug("%s: %s %s\n", __func__, dev_name, dmp->udev_name);

       SLIST_INSERT_HEAD(&dm_pdev_list, dmp, next_pdev);
       mutex_exit(&dm_pdev_mutex);

       return dmp;
}

/*
* Initialize pdev subsystem.
*/
int
dm_pdev_init(void)
{

       SLIST_INIT(&dm_pdev_list);      /* initialize global pdev list */
       mutex_init(&dm_pdev_mutex, MUTEX_DEFAULT, IPL_NONE);

       return 0;
}

/*
* Allocat new pdev structure if is not already present and
* set name.
*/
static dm_pdev_t *
dm_pdev_alloc(const char *name)
{
       dm_pdev_t *dmp;

       dmp = kmem_zalloc(sizeof(*dmp), KM_SLEEP);
       strlcpy(dmp->name, name, sizeof(dmp->name));
       dmp->ref_cnt = 0;
       dmp->pdev_vnode = NULL;

       return dmp;
}

/*
* Destroy allocated dm_pdev.
*/
static int
dm_pdev_rem(dm_pdev_t *dmp)
{

       KASSERT(dmp != NULL);

       if (dmp->pdev_vnode != NULL) {
               int error = vn_close(dmp->pdev_vnode, FREAD | FWRITE, FSCRED);
               if (error != 0) {
                       kmem_free(dmp, sizeof(*dmp));
                       return error;
               }
       }
       kmem_free(dmp, sizeof(*dmp));

       return 0;
}

/*
* Destroy all existing pdev's in device-mapper.
*/
int
dm_pdev_destroy(void)
{
       dm_pdev_t *dmp;

       mutex_enter(&dm_pdev_mutex);

       while ((dmp = SLIST_FIRST(&dm_pdev_list)) != NULL) {
               SLIST_REMOVE(&dm_pdev_list, dmp, dm_pdev, next_pdev);
               dm_pdev_rem(dmp);
       }
       KASSERT(SLIST_EMPTY(&dm_pdev_list));

       mutex_exit(&dm_pdev_mutex);

       mutex_destroy(&dm_pdev_mutex);
       return 0;
}

/*
* This function is called from dm_dev_remove_ioctl.
* When I'm removing device from list, I have to decrement
* reference counter. If reference counter is 0 I will remove
* dmp from global list and from device list to. And I will CLOSE
* dmp vnode too.
*/

/*
* Decrement pdev reference counter if 0 remove it.
*/
int
dm_pdev_decr(dm_pdev_t *dmp)
{

       KASSERT(dmp != NULL);
       /*
        * If this was last reference remove dmp from
        * global list also.
        */
       mutex_enter(&dm_pdev_mutex);

       if (--dmp->ref_cnt == 0) {
               SLIST_REMOVE(&dm_pdev_list, dmp, dm_pdev, next_pdev);
               mutex_exit(&dm_pdev_mutex);
               dm_pdev_rem(dmp);
               return 0;
       }

       mutex_exit(&dm_pdev_mutex);
       return 0;
}

#if 0
static int
dm_pdev_dump_list(void)
{
       dm_pdev_t *dmp;

       aprint_verbose("Dumping dm_pdev_list\n");

       SLIST_FOREACH(dmp, &dm_pdev_list, next_pdev) {
               aprint_verbose("dm_pdev_name %s ref_cnt %d list_rf_cnt %d\n",
               dmp->name, dmp->ref_cnt, dmp->list_ref_cnt);
       }

       return 0;
}
#endif

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