/* $NetBSD: udf_strat_sequential.c,v 1.20 2023/06/27 09:58:50 reinoud Exp $ */

/*
* Copyright (c) 2006, 2008 Reinoud Zandijk
* All rights reserved.
*
* 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 AUTHOR ``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 AUTHOR 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>
#ifndef lint
__KERNEL_RCSID(0, "$NetBSD: udf_strat_sequential.c,v 1.20 2023/06/27 09:58:50 reinoud Exp $");
#endif /* not lint */


#if defined(_KERNEL_OPT)
#include "opt_compat_netbsd.h"
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <miscfs/genfs/genfs_node.h>
#include <sys/mount.h>
#include <sys/buf.h>
#include <sys/file.h>
#include <sys/device.h>
#include <sys/disklabel.h>
#include <sys/ioctl.h>
#include <sys/malloc.h>
#include <sys/dirent.h>
#include <sys/stat.h>
#include <sys/conf.h>
#include <sys/kauth.h>
#include <sys/kthread.h>
#include <dev/clock_subr.h>

#include <fs/udf/ecma167-udf.h>
#include <fs/udf/udf_mount.h>

#include "udf.h"
#include "udf_subr.h"
#include "udf_bswap.h"


#define VTOI(vnode) ((struct udf_node *) vnode->v_data)
#define PRIV(ump) ((struct strat_private *) ump->strategy_private)

/* --------------------------------------------------------------------- */

/* BUFQ's */
#define UDF_SHED_MAX 3

#define UDF_SHED_READING        0
#define UDF_SHED_WRITING        1
#define UDF_SHED_SEQWRITING     2

struct strat_private {
       struct pool              desc_pool;             /* node descriptors */

       lwp_t                   *queue_lwp;
       kcondvar_t               discstrat_cv;          /* to wait on       */
       kmutex_t                 discstrat_mutex;       /* disc strategy    */

       int                      thread_running;        /* thread control */
       int                      run_thread;            /* thread control */
       int                      thread_finished;       /* thread control */

       int                      sync_req;              /* thread control */
       int                      cur_queue;

       struct disk_strategy     old_strategy_setting;
       struct bufq_state       *queues[UDF_SHED_MAX];
       struct timespec          last_queued[UDF_SHED_MAX];
};


/* --------------------------------------------------------------------- */

static void
udf_wr_nodedscr_callback(struct buf *buf)
{
       struct udf_node *udf_node;

       KASSERT(buf);
       KASSERT(buf->b_data);

       /* called when write action is done */
       DPRINTF(WRITE, ("udf_wr_nodedscr_callback(): node written out\n"));

       udf_node = VTOI(buf->b_vp);
       if (udf_node == NULL) {
               putiobuf(buf);
               printf("udf_wr_node_callback: NULL node?\n");
               return;
       }

       /* XXX right flags to mark dirty again on error? */
       if (buf->b_error) {
               udf_node->i_flags |= IN_MODIFIED | IN_ACCESSED;
               /* XXX TODO reschedule on error */
       }

       /* decrement outstanding_nodedscr */
       KASSERT(udf_node->outstanding_nodedscr >= 1);
       udf_node->outstanding_nodedscr--;
       if (udf_node->outstanding_nodedscr == 0) {
               /* first unlock the node */
               UDF_UNLOCK_NODE(udf_node, 0);
               cv_broadcast(&udf_node->node_lock);
       }

       putiobuf(buf);
}

/* --------------------------------------------------------------------- */

static int
udf_create_logvol_dscr_seq(struct udf_strat_args *args)
{
       union dscrptr   **dscrptr = &args->dscr;
       struct udf_mount *ump = args->ump;
       struct strat_private *priv = PRIV(ump);
       uint32_t lb_size;

       lb_size = udf_rw32(ump->logical_vol->lb_size);
       *dscrptr = pool_get(&priv->desc_pool, PR_WAITOK);
       memset(*dscrptr, 0, lb_size);

       return 0;
}


static void
udf_free_logvol_dscr_seq(struct udf_strat_args *args)
{
       union dscrptr    *dscr = args->dscr;
       struct udf_mount *ump  = args->ump;
       struct strat_private *priv = PRIV(ump);

       pool_put(&priv->desc_pool, dscr);
}


static int
udf_read_logvol_dscr_seq(struct udf_strat_args *args)
{
       union dscrptr   **dscrptr = &args->dscr;
       union dscrptr    *tmpdscr;
       struct udf_mount *ump = args->ump;
       struct long_ad   *icb = args->icb;
       struct strat_private *priv = PRIV(ump);
       uint32_t lb_size;
       uint32_t sector, dummy;
       int error;

       lb_size = udf_rw32(ump->logical_vol->lb_size);

       error = udf_translate_vtop(ump, icb, &sector, &dummy);
       if (error)
               return error;

       /* try to read in fe/efe */
       error = udf_read_phys_dscr(ump, sector, M_UDFTEMP, &tmpdscr);
       if (error)
               return error;

       *dscrptr = pool_get(&priv->desc_pool, PR_WAITOK);
       memcpy(*dscrptr, tmpdscr, lb_size);
       free(tmpdscr, M_UDFTEMP);

       return 0;
}


static int
udf_write_logvol_dscr_seq(struct udf_strat_args *args)
{
       union dscrptr    *dscr     = args->dscr;
       struct udf_mount *ump      = args->ump;
       struct udf_node  *udf_node = args->udf_node;
       struct long_ad   *icb      = args->icb;
       int               waitfor  = args->waitfor;
       uint32_t logsectornr, sectornr, dummy;
       int error, vpart;

       /*
        * we have to decide if we write it out sequential or at its fixed
        * position by examining the partition its (to be) written on.
        */
       vpart       = udf_rw16(udf_node->loc.loc.part_num);
       logsectornr = udf_rw32(icb->loc.lb_num);
       sectornr    = 0;
       if (ump->vtop_tp[vpart] != UDF_VTOP_TYPE_VIRT) {
               error = udf_translate_vtop(ump, icb, &sectornr, &dummy);
               if (error)
                       goto out;
       }

       if (waitfor) {
               DPRINTF(WRITE, ("udf_write_logvol_dscr: sync write\n"));

               error = udf_write_phys_dscr_sync(ump, udf_node, UDF_C_NODE,
                       dscr, sectornr, logsectornr);
       } else {
               DPRINTF(WRITE, ("udf_write_logvol_dscr: no wait, async write\n"));

               error = udf_write_phys_dscr_async(ump, udf_node, UDF_C_NODE,
                       dscr, sectornr, logsectornr, udf_wr_nodedscr_callback);
               /* will be UNLOCKED in call back */
               return error;
       }
out:
       udf_node->outstanding_nodedscr--;
       if (udf_node->outstanding_nodedscr == 0) {
               UDF_UNLOCK_NODE(udf_node, 0);
               cv_broadcast(&udf_node->node_lock);
       }

       return error;
}

/* --------------------------------------------------------------------- */

/*
* Main file-system specific scheduler. Due to the nature of optical media
* scheduling can't be performed in the traditional way. Most OS
* implementations i've seen thus read or write a file atomically giving all
* kinds of side effects.
*
* This implementation uses a kernel thread to schedule the queued requests in
* such a way that is semi-optimal for optical media; this means approximately
* (R*|(Wr*|Ws*))* since switching between reading and writing is expensive in
* time.
*/

static void
udf_queuebuf_seq(struct udf_strat_args *args)
{
       struct udf_mount *ump = args->ump;
       struct buf *nestbuf = args->nestbuf;
       struct strat_private *priv = PRIV(ump);
       int queue;
       int what;

       KASSERT(ump);
       KASSERT(nestbuf);
       KASSERT(nestbuf->b_iodone == nestiobuf_iodone);

       what = nestbuf->b_udf_c_type;
       queue = UDF_SHED_READING;
       if ((nestbuf->b_flags & B_READ) == 0) {
               /* writing */
               queue = UDF_SHED_SEQWRITING;
               if (what == UDF_C_ABSOLUTE)
                       queue = UDF_SHED_WRITING;
       }

       /* use our own scheduler lists for more complex scheduling */
       mutex_enter(&priv->discstrat_mutex);
               bufq_put(priv->queues[queue], nestbuf);
               vfs_timestamp(&priv->last_queued[queue]);
       mutex_exit(&priv->discstrat_mutex);

       /* signal our thread that there might be something to do */
       cv_signal(&priv->discstrat_cv);
}

/* --------------------------------------------------------------------- */

static void
udf_sync_caches_seq(struct udf_strat_args *args)
{
       struct udf_mount *ump = args->ump;
       struct strat_private *priv = PRIV(ump);

       /* we might be called during unmount inadvertedly, be on safe side */
       if (!priv)
               return;

       /* signal our thread that there might be something to do */
       priv->sync_req = 1;
       cv_signal(&priv->discstrat_cv);

       mutex_enter(&priv->discstrat_mutex);
               while (priv->sync_req) {
                       cv_timedwait(&priv->discstrat_cv,
                               &priv->discstrat_mutex, hz/8);
               }
       mutex_exit(&priv->discstrat_mutex);
}

/* --------------------------------------------------------------------- */

/* TODO convert to lb_size */
static void
udf_VAT_mapping_update(struct udf_mount *ump, struct buf *buf, uint32_t lb_map)
{
       union dscrptr    *fdscr = (union dscrptr *) buf->b_data;
       struct vnode     *vp = buf->b_vp;
       struct udf_node  *udf_node = VTOI(vp);
       uint32_t lb_num;
       uint32_t udf_rw32_lbmap;
       int c_type = buf->b_udf_c_type;
       int error;

       /* only interested when we're using a VAT */
       KASSERT(ump->vat_node);
       KASSERT(ump->vtop_alloc[ump->node_part] == UDF_ALLOC_VAT);

       /* only nodes are recorded in the VAT */
       /* NOTE: and the fileset descriptor (FIXME ?) */
       if (c_type != UDF_C_NODE)
               return;

       udf_rw32_lbmap = udf_rw32(lb_map);

       /* if we're the VAT itself, only update our assigned sector number */
       if (udf_node == ump->vat_node) {
               fdscr->tag.tag_loc = udf_rw32_lbmap;
               udf_validate_tag_sum(fdscr);
               DPRINTF(TRANSLATE, ("VAT assigned to sector %u\n",
                       udf_rw32(udf_rw32_lbmap)));
               /* no use mapping the VAT node in the VAT */
               return;
       }

       /* record new position in VAT file */
       lb_num = udf_rw32(fdscr->tag.tag_loc);

       /* lb_num = udf_rw32(udf_node->write_loc.loc.lb_num); */

       DPRINTF(TRANSLATE, ("VAT entry change (log %u -> phys %u)\n",
                       lb_num, lb_map));

       /* VAT should be the longer than this write, can't go wrong */
       KASSERT(lb_num <= ump->vat_entries);

       mutex_enter(&ump->allocate_mutex);
       error = udf_vat_write(ump->vat_node,
                       (uint8_t *) &udf_rw32_lbmap, 4,
                       ump->vat_offset + lb_num * 4);
       mutex_exit(&ump->allocate_mutex);

       if (error)
               panic( "udf_VAT_mapping_update: HELP! i couldn't "
                       "write in the VAT file ?\n");
}


static void
udf_issue_buf(struct udf_mount *ump, int queue, struct buf *buf)
{
       union dscrptr *dscr;
       struct long_ad *node_ad_cpy;
       struct part_desc *pdesc;
       uint64_t *lmapping, *lmappos;
       uint32_t sectornr, bpos;
       uint32_t ptov;
       uint16_t vpart_num;
       uint8_t *fidblk;
       int sector_size = ump->discinfo.sector_size;
       int blks = sector_size / DEV_BSIZE;
       int len, buf_len;

       /* if reading, just pass to the device's STRATEGY */
       if (queue == UDF_SHED_READING) {
               DPRINTF(SHEDULE, ("\nudf_issue_buf READ %p : sector %d type %d,"
                       "b_resid %d, b_bcount %d, b_bufsize %d\n",
                       buf, (uint32_t) buf->b_blkno / blks, buf->b_udf_c_type,
                       buf->b_resid, buf->b_bcount, buf->b_bufsize));
               VOP_STRATEGY(ump->devvp, buf);
               return;
       }

       if (queue == UDF_SHED_WRITING) {
               DPRINTF(SHEDULE, ("\nudf_issue_buf WRITE %p : sector %d "
                       "type %d, b_resid %d, b_bcount %d, b_bufsize %d\n",
                       buf, (uint32_t) buf->b_blkno / blks, buf->b_udf_c_type,
                       buf->b_resid, buf->b_bcount, buf->b_bufsize));
               KASSERT(buf->b_udf_c_type == UDF_C_ABSOLUTE);

               // udf_fixup_node_internals(ump, buf->b_data, buf->b_udf_c_type);
               VOP_STRATEGY(ump->devvp, buf);
               return;
       }

       KASSERT(queue == UDF_SHED_SEQWRITING);
       DPRINTF(SHEDULE, ("\nudf_issue_buf SEQWRITE %p : sector XXXX "
               "type %d, b_resid %d, b_bcount %d, b_bufsize %d\n",
               buf, buf->b_udf_c_type, buf->b_resid, buf->b_bcount,
               buf->b_bufsize));

       /*
        * Buffers should not have been allocated to disc addresses yet on
        * this queue. Note that a buffer can get multiple extents allocated.
        *
        * lmapping contains lb_num relative to base partition.
        */
       lmapping    = ump->la_lmapping;
       node_ad_cpy = ump->la_node_ad_cpy;

       /* logically allocate buf and map it in the file */
       udf_late_allocate_buf(ump, buf, lmapping, node_ad_cpy, &vpart_num);

       /*
        * NOTE We are using the knowledge here that sequential media will
        * always be mapped linearly. Thus no use to explicitly translate the
        * lmapping list.
        */

       /* calculate offset from physical base partition */
       pdesc = ump->partitions[ump->vtop[vpart_num]];
       ptov  = udf_rw32(pdesc->start_loc);

       /* set buffers blkno to the physical block number */
       buf->b_blkno = (*lmapping + ptov) * blks;

       /* fixate floating descriptors */
       if (buf->b_udf_c_type == UDF_C_FLOAT_DSCR) {
               /* set our tag location to the absolute position */
               dscr = (union dscrptr *) buf->b_data;
               dscr->tag.tag_loc = udf_rw32(*lmapping + ptov);
               udf_validate_tag_and_crc_sums(dscr);
       }

       /* update mapping in the VAT */
       if (buf->b_udf_c_type == UDF_C_NODE) {
               udf_VAT_mapping_update(ump, buf, *lmapping);
               udf_fixup_node_internals(ump, buf->b_data, buf->b_udf_c_type);
       }

       /* if we have FIDs, fixup using the new allocation table */
       if (buf->b_udf_c_type == UDF_C_FIDS) {
               buf_len = buf->b_bcount;
               bpos = 0;
               lmappos = lmapping;
               while (buf_len) {
                       sectornr = *lmappos++;
                       len = MIN(buf_len, sector_size);
                       fidblk = (uint8_t *) buf->b_data + bpos;
                       udf_fixup_fid_block(fidblk, sector_size,
                               0, len, sectornr);
                       bpos += len;
                       buf_len -= len;
               }
       }

       VOP_STRATEGY(ump->devvp, buf);
}


static void
udf_doshedule(struct udf_mount *ump)
{
       struct buf *buf;
       struct timespec now, *last;
       struct strat_private *priv = PRIV(ump);
       void (*b_callback)(struct buf *);
       int new_queue;
       int error;

       buf = bufq_get(priv->queues[priv->cur_queue]);
       if (buf) {
               /* transfer from the current queue to the device queue */
               mutex_exit(&priv->discstrat_mutex);

               /* transform buffer to synchronous; XXX needed? */
               b_callback = buf->b_iodone;
               buf->b_iodone = NULL;
               CLR(buf->b_flags, B_ASYNC);

               /* issue and wait on completion */
               udf_issue_buf(ump, priv->cur_queue, buf);
               biowait(buf);

               mutex_enter(&priv->discstrat_mutex);

               /* if there is an error, repair this error, otherwise propagate */
               if (buf->b_error && ((buf->b_flags & B_READ) == 0)) {
                       /* check what we need to do */
                       panic("UDF write error, can't handle yet!\n");
               }

               /* propagate result to higher layers */
               if (b_callback) {
                       buf->b_iodone = b_callback;
                       (*buf->b_iodone)(buf);
               }

               return;
       }

       /* Check if we're idling in this state */
       vfs_timestamp(&now);
       last = &priv->last_queued[priv->cur_queue];
       if (ump->discinfo.mmc_class == MMC_CLASS_CD) {
               /* dont switch too fast for CD media; its expensive in time */
               if (now.tv_sec - last->tv_sec < 3)
                       return;
       }

       /* check if we can/should switch */
       new_queue = priv->cur_queue;

       if (bufq_peek(priv->queues[UDF_SHED_READING]))
               new_queue = UDF_SHED_READING;
       if (bufq_peek(priv->queues[UDF_SHED_WRITING]))          /* only for unmount */
               new_queue = UDF_SHED_WRITING;
       if (bufq_peek(priv->queues[UDF_SHED_SEQWRITING]))
               new_queue = UDF_SHED_SEQWRITING;
       if (priv->cur_queue == UDF_SHED_READING) {
               if (new_queue == UDF_SHED_SEQWRITING) {
                       /* TODO use flag to signal if this is needed */
                       mutex_exit(&priv->discstrat_mutex);

                       /* update trackinfo for data and metadata */
                       error = udf_update_trackinfo(ump,
                                       &ump->data_track);
                       assert(error == 0);
                       error = udf_update_trackinfo(ump,
                                       &ump->metadata_track);
                       assert(error == 0);
                       mutex_enter(&priv->discstrat_mutex);
                       __USE(error);
               }
       }

       if (new_queue != priv->cur_queue) {
               DPRINTF(SHEDULE, ("switching from %d to %d\n",
                       priv->cur_queue, new_queue));
               if (new_queue == UDF_SHED_READING)
                       udf_mmc_synchronise_caches(ump);
       }

       priv->cur_queue = new_queue;
}


static void
udf_discstrat_thread(void *arg)
{
       struct udf_mount *ump = (struct udf_mount *) arg;
       struct strat_private *priv = PRIV(ump);
       int empty;

       empty = 1;

       priv->thread_running = 1;
       cv_broadcast(&priv->discstrat_cv);

       mutex_enter(&priv->discstrat_mutex);
       while (priv->run_thread || !empty || priv->sync_req) {
               /* process the current selected queue */
               udf_doshedule(ump);
               empty  = (bufq_peek(priv->queues[UDF_SHED_READING]) == NULL);
               empty &= (bufq_peek(priv->queues[UDF_SHED_WRITING]) == NULL);
               empty &= (bufq_peek(priv->queues[UDF_SHED_SEQWRITING]) == NULL);

               /* wait for more if needed */
               if (empty) {
                       if (priv->sync_req) {
                               /* on sync, we need to simulate a read->write transition */
                               udf_mmc_synchronise_caches(ump);
                               priv->cur_queue = UDF_SHED_READING;
                               priv->sync_req = 0;
                       }
                       cv_timedwait(&priv->discstrat_cv,
                               &priv->discstrat_mutex, hz/8);
               }
       }
       mutex_exit(&priv->discstrat_mutex);

       priv->thread_running  = 0;
       priv->thread_finished = 1;
       cv_broadcast(&priv->discstrat_cv);

       kthread_exit(0);
       /* not reached */
}

/* --------------------------------------------------------------------- */

static void
udf_discstrat_init_seq(struct udf_strat_args *args)
{
       struct udf_mount *ump = args->ump;
       struct strat_private *priv = PRIV(ump);
       struct disk_strategy dkstrat;
       uint32_t lb_size;

       KASSERT(ump);
       KASSERT(ump->logical_vol);
       KASSERT(priv == NULL);

       lb_size = udf_rw32(ump->logical_vol->lb_size);
       KASSERT(lb_size > 0);

       /* initialise our memory space */
       ump->strategy_private = malloc(sizeof(struct strat_private),
               M_UDFTEMP, M_WAITOK);
       priv = ump->strategy_private;
       memset(priv, 0 , sizeof(struct strat_private));

       /* initialise locks */
       cv_init(&priv->discstrat_cv, "udfstrat");
       mutex_init(&priv->discstrat_mutex, MUTEX_DEFAULT, IPL_NONE);

       /*
        * Initialise pool for descriptors associated with nodes. This is done
        * in lb_size units though currently lb_size is dictated to be
        * sector_size.
        */
       pool_init(&priv->desc_pool, lb_size, 0, 0, 0, "udf_desc_pool", NULL,
           IPL_NONE);

       /*
        * remember old device strategy method and explicit set method
        * `discsort' since we have our own more complex strategy that is not
        * implementable on the CD device and other strategies will get in the
        * way.
        */
       memset(&priv->old_strategy_setting, 0,
               sizeof(struct disk_strategy));
       VOP_IOCTL(ump->devvp, DIOCGSTRATEGY, &priv->old_strategy_setting,
               FREAD | FKIOCTL, NOCRED);
       memset(&dkstrat, 0, sizeof(struct disk_strategy));
       strcpy(dkstrat.dks_name, "discsort");
       VOP_IOCTL(ump->devvp, DIOCSSTRATEGY, &dkstrat, FWRITE | FKIOCTL,
               NOCRED);

       /* initialise our internal scheduler */
       priv->cur_queue = UDF_SHED_READING;
       bufq_alloc(&priv->queues[UDF_SHED_READING], "disksort",
               BUFQ_SORT_RAWBLOCK);
       bufq_alloc(&priv->queues[UDF_SHED_WRITING], "disksort",
               BUFQ_SORT_RAWBLOCK);
       bufq_alloc(&priv->queues[UDF_SHED_SEQWRITING], "fcfs", 0);
       vfs_timestamp(&priv->last_queued[UDF_SHED_READING]);
       vfs_timestamp(&priv->last_queued[UDF_SHED_WRITING]);
       vfs_timestamp(&priv->last_queued[UDF_SHED_SEQWRITING]);

       /* create our disk strategy thread */
       priv->thread_finished = 0;
       priv->thread_running  = 0;
       priv->run_thread      = 1;
       priv->sync_req        = 0;
       if (kthread_create(PRI_NONE, 0 /* KTHREAD_MPSAFE*/, NULL /* cpu_info*/,
               udf_discstrat_thread, ump, &priv->queue_lwp,
               "%s", "udf_rw")) {
               panic("fork udf_rw");
       }

       /* wait for thread to spin up */
       mutex_enter(&priv->discstrat_mutex);
       while (!priv->thread_running) {
               cv_timedwait(&priv->discstrat_cv, &priv->discstrat_mutex, hz);
       }
       mutex_exit(&priv->discstrat_mutex);
}


static void
udf_discstrat_finish_seq(struct udf_strat_args *args)
{
       struct udf_mount *ump = args->ump;
       struct strat_private *priv = PRIV(ump);

       if (ump == NULL)
               return;

       /* stop our scheduling thread */
       KASSERT(priv->run_thread == 1);
       priv->run_thread = 0;

       mutex_enter(&priv->discstrat_mutex);
       while (!priv->thread_finished) {
               cv_broadcast(&priv->discstrat_cv);
               cv_timedwait(&priv->discstrat_cv, &priv->discstrat_mutex, hz);
       }
       mutex_exit(&priv->discstrat_mutex);

       /* kthread should be finished now */

       /* set back old device strategy method */
       VOP_IOCTL(ump->devvp, DIOCSSTRATEGY, &priv->old_strategy_setting,
                       FWRITE, NOCRED);

       /* destroy our pool */
       pool_destroy(&priv->desc_pool);

       mutex_destroy(&priv->discstrat_mutex);
       cv_destroy(&priv->discstrat_cv);

       /* free our private space */
       free(ump->strategy_private, M_UDFTEMP);
       ump->strategy_private = NULL;
}

/* --------------------------------------------------------------------- */

struct udf_strategy udf_strat_sequential =
{
       udf_create_logvol_dscr_seq,
       udf_free_logvol_dscr_seq,
       udf_read_logvol_dscr_seq,
       udf_write_logvol_dscr_seq,
       udf_queuebuf_seq,
       udf_sync_caches_seq,
       udf_discstrat_init_seq,
       udf_discstrat_finish_seq
};