sys/dev/disk/dm/device-mapper.c

   1 /*        $NetBSD: device-mapper.c,v 1.22 2010/03/26 15:46:04 jakllsch Exp $ */
   2
   3 /*
   4  * Copyright (c) 2010 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Adam Hamsik.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 /*
  33  * I want to say thank you to all people who helped me with this project.
  34  */
  35
  36 #include <sys/types.h>
  37 #include <sys/param.h>
  38
  39 #include <sys/buf.h>
  40 #include <sys/conf.h>
  41 #include <sys/device.h>
  42 #include <sys/devfs.h>
  43 #include <sys/disk.h>
  44 #include <sys/disklabel.h>
  45 #include <sys/dtype.h>
  46 #include <sys/ioccom.h>
  47 #include <sys/malloc.h>
  48 #include <sys/module.h>
  49 #include <sys/sysctl.h>
  50
  51 #include "netbsd-dm.h"
  52 #include "dm.h"
  53
  54 static  d_ioctl_t       dmioctl;
  55 static  d_open_t        dmopen;
  56 static  d_close_t       dmclose;
  57 static  d_psize_t       dmsize;
  58 static  d_strategy_t    dmstrategy;
  59 static  d_dump_t        dmdump;
  60
  61 /* attach and detach routines */
  62 void dmattach(int);
  63 static int dm_modcmd(module_t mod, int cmd, void *unused);
  64 static int dmdestroy(void);
  65
  66 static void dm_doinit(void);
  67
  68 static int dm_cmd_to_fun(prop_dictionary_t);
  69 static int disk_ioctl_switch(cdev_t, u_long, void *);
  70 static int dm_ioctl_switch(u_long);
  71 #if 0
  72 static void dmminphys(struct buf *);
  73 #endif
  74
  75 struct devfs_bitmap dm_minor_bitmap;
  76
  77 /* ***Variable-definitions*** */
  78 struct dev_ops dm_ops = {
  79         { "dm", 0, D_DISK | D_MPSAFE },
  80         .d_open         = dmopen,
  81         .d_close        = dmclose,
  82         .d_read         = physread,
  83         .d_write        = physwrite,
  84         .d_ioctl        = dmioctl,
  85         .d_strategy     = dmstrategy,
  86         .d_psize        = dmsize,
  87         .d_dump         = dmdump,
  88 /* D_DISK */
  89 };
  90
  91 MALLOC_DEFINE(M_DM, "dm", "Device Mapper allocations");
  92
  93 int dm_debug_level = 0;
  94
  95 extern uint64_t dm_dev_counter;
  96
  97 static cdev_t dmcdev;
  98
  99 static moduledata_t dm_mod = {
 100     "dm",
 101     dm_modcmd,
 102     NULL
 103 };
 104 DECLARE_MODULE(dm, dm_mod, SI_SUB_RAID, SI_ORDER_ANY);
 105
 106 /*
 107  * This array is used to translate cmd to function pointer.
 108  *
 109  * Interface between libdevmapper and lvm2tools uses different
 110  * names for one IOCTL call because libdevmapper do another thing
 111  * then. When I run "info" or "mknodes" libdevmapper will send same
 112  * ioctl to kernel but will do another things in userspace.
 113  *
 114  */
 115 static struct cmd_function cmd_fn[] = {
 116                 { .cmd = "version", .fn = dm_get_version_ioctl},
 117                 { .cmd = "targets", .fn = dm_list_versions_ioctl},
 118                 { .cmd = "create",  .fn = dm_dev_create_ioctl},
 119                 { .cmd = "info",    .fn = dm_dev_status_ioctl},
 120                 { .cmd = "mknodes", .fn = dm_dev_status_ioctl},
 121                 { .cmd = "names",   .fn = dm_dev_list_ioctl},
 122                 { .cmd = "suspend", .fn = dm_dev_suspend_ioctl},
 123                 { .cmd = "remove",  .fn = dm_dev_remove_ioctl},
 124                 { .cmd = "rename",  .fn = dm_dev_rename_ioctl},
 125                 { .cmd = "resume",  .fn = dm_dev_resume_ioctl},
 126                 { .cmd = "clear",   .fn = dm_table_clear_ioctl},
 127                 { .cmd = "deps",    .fn = dm_table_deps_ioctl},
 128                 { .cmd = "reload",  .fn = dm_table_load_ioctl},
 129                 { .cmd = "status",  .fn = dm_table_status_ioctl},
 130                 { .cmd = "table",   .fn = dm_table_status_ioctl},
 131                 {NULL, NULL}
 132 };
 133
 134 /* New module handle routine */
 135 static int
 136 dm_modcmd(module_t mod, int cmd, void *unused)
 137 {
 138         int error, bmajor, cmajor;
 139
 140         error = 0;
 141         bmajor = -1;
 142         cmajor = -1;
 143
 144         switch (cmd) {
 145         case MOD_LOAD:
 146                 devfs_clone_bitmap_init(&dm_minor_bitmap);
 147                 dm_doinit();
 148                 kprintf("Device Mapper version %d.%d.%d loaded\n",
 149                     DM_VERSION_MAJOR, DM_VERSION_MINOR, DM_VERSION_PATCHLEVEL);
 150                 break;
 151
 152         case MOD_UNLOAD:
 153                 /*
 154                  * Disable unloading of dm module if there are any devices
 155                  * defined in driver. This is probably too strong we need
 156                  * to disable auto-unload only if there is mounted dm device
 157                  * present.
 158                  */
 159                 if (dm_dev_counter > 0)
 160                         return EBUSY;
 161
 162                 error = dmdestroy();
 163                 if (error)
 164                         break;
 165                 kprintf("Device Mapper unloaded\n");
 166                 break;
 167
 168         default:
 169                 break;
 170         }
 171
 172         return error;
 173 }
 174
 175 /*
 176  * dm_detach:
 177  *
 178  *      Autoconfiguration detach function for pseudo-device glue.
 179  * This routine is called by dm_ioctl::dm_dev_remove_ioctl and by autoconf to
 180  * remove devices created in device-mapper.
 181  */
 182 int
 183 dm_detach(dm_dev_t *dmv)
 184 {
 185         int minor;
 186
 187         /* Remove device from list and wait for refcnt to drop to zero */
 188         dm_dev_rem(dmv, NULL, NULL, -1);
 189
 190         /* Destroy active table first.  */
 191         dm_table_destroy(&dmv->table_head, DM_TABLE_ACTIVE);
 192
 193         /* Destroy inactive table if exits, too. */
 194         dm_table_destroy(&dmv->table_head, DM_TABLE_INACTIVE);
 195
 196         dm_table_head_destroy(&dmv->table_head);
 197
 198         minor = dkunit(dmv->devt);
 199         disk_destroy(dmv->diskp);
 200         devstat_remove_entry(&dmv->stats);
 201
 202         release_dev(dmv->devt);
 203         devfs_clone_bitmap_put(&dm_minor_bitmap, minor);
 204
 205         /* Destroy device */
 206         (void)dm_dev_free(dmv);
 207
 208         /* Decrement device counter After removing device */
 209         --dm_dev_counter; /* XXX: was atomic 64 */
 210
 211         return 0;
 212 }
 213
 214 static void
 215 dm_doinit(void)
 216 {
 217         dm_target_init();
 218         dm_dev_init();
 219         dm_pdev_init();
 220         dmcdev = make_dev(&dm_ops, 0, UID_ROOT, GID_OPERATOR, 0640, "mapper/control");
 221 }
 222
 223 /* Destroy routine */
 224 static int
 225 dmdestroy(void)
 226 {
 227         destroy_dev(dmcdev);
 228
 229         dm_dev_destroy();
 230         dm_pdev_destroy();
 231         dm_target_destroy();
 232
 233         return 0;
 234 }
 235
 236 static int
 237 dmopen(struct dev_open_args *ap)
 238 {
 239         cdev_t dev = ap->a_head.a_dev;
 240         dm_dev_t *dmv;
 241
 242         /* Shortcut for the control device */
 243         if (minor(dev) == 0)
 244                 return 0;
 245
 246         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL)
 247                 return ENXIO;
 248
 249         dmv->is_open = 1;
 250         dm_dev_unbusy(dmv);
 251
 252         aprint_debug("dm open routine called %" PRIu32 "\n",
 253             minor(ap->a_head.a_dev));
 254         return 0;
 255 }
 256
 257 static int
 258 dmclose(struct dev_close_args *ap)
 259 {
 260         cdev_t dev = ap->a_head.a_dev;
 261         dm_dev_t *dmv;
 262
 263         /* Shortcut for the control device */
 264         if (minor(dev) == 0)
 265                 return 0;
 266
 267         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL)
 268                 return ENXIO;
 269
 270         dmv->is_open = 0;
 271         dm_dev_unbusy(dmv);
 272
 273         aprint_debug("dm close routine called %" PRIu32 "\n",
 274             minor(ap->a_head.a_dev));
 275         return 0;
 276 }
 277
 278
 279 static int
 280 dmioctl(struct dev_ioctl_args *ap)
 281 {
 282         cdev_t dev = ap->a_head.a_dev;
 283         u_long cmd = ap->a_cmd;
 284         void *data = ap->a_data;
 285
 286         int r, err;
 287         prop_dictionary_t dm_dict_in;
 288
 289         err = r = 0;
 290
 291         aprint_debug("dmioctl called\n");
 292
 293         KKASSERT(data != NULL);
 294
 295         if (( r = disk_ioctl_switch(dev, cmd, data)) == ENOTTY) {
 296                 struct plistref *pref = (struct plistref *) data;
 297
 298                 /* Check if we were called with NETBSD_DM_IOCTL ioctl
 299                    otherwise quit. */
 300                 if ((r = dm_ioctl_switch(cmd)) != 0)
 301                         return r;
 302
 303                 if((r = prop_dictionary_copyin_ioctl(pref, cmd, &dm_dict_in)) != 0)
 304                         return r;
 305
 306                 if ((r = dm_check_version(dm_dict_in)) != 0)
 307                         goto cleanup_exit;
 308
 309                 /* run ioctl routine */
 310                 if ((err = dm_cmd_to_fun(dm_dict_in)) != 0)
 311                         goto cleanup_exit;
 312
 313 cleanup_exit:
 314                 r = prop_dictionary_copyout_ioctl(pref, cmd, dm_dict_in);
 315                 prop_object_release(dm_dict_in);
 316         }
 317
 318         /*
 319          * Return the error of the actual command if one one has
 320          * happened. Otherwise return 'r' which indicates errors
 321          * that occurred during helper operations.
 322          */
 323         return (err != 0)?err:r;
 324 }
 325
 326 /*
 327  * Translate command sent from libdevmapper to func.
 328  */
 329 static int
 330 dm_cmd_to_fun(prop_dictionary_t dm_dict){
 331         int i, r;
 332         prop_string_t command;
 333
 334         r = 0;
 335
 336         if ((command = prop_dictionary_get(dm_dict, DM_IOCTL_COMMAND)) == NULL)
 337                 return EINVAL;
 338
 339         for(i = 0; cmd_fn[i].cmd != NULL; i++)
 340                 if (prop_string_equals_cstring(command, cmd_fn[i].cmd))
 341                         break;
 342
 343         if (cmd_fn[i].cmd == NULL)
 344                 return EINVAL;
 345
 346         aprint_debug("ioctl %s called\n", cmd_fn[i].cmd);
 347         r = cmd_fn[i].fn(dm_dict);
 348
 349         return r;
 350 }
 351
 352 /* Call apropriate ioctl handler function. */
 353 static int
 354 dm_ioctl_switch(u_long cmd)
 355 {
 356
 357         switch(cmd) {
 358
 359         case NETBSD_DM_IOCTL:
 360                 aprint_debug("dm NetBSD_DM_IOCTL called\n");
 361                 break;
 362         default:
 363                  aprint_debug("dm unknown ioctl called\n");
 364                  return ENOTTY;
 365                  break; /* NOT REACHED */
 366         }
 367
 368          return 0;
 369 }
 370
 371  /*
 372   * Check for disk specific ioctls.
 373   */
 374
 375 static int
 376 disk_ioctl_switch(cdev_t dev, u_long cmd, void *data)
 377 {
 378         dm_dev_t *dmv;
 379
 380         /* disk ioctls make sense only on block devices */
 381         if (minor(dev) == 0)
 382                 return ENOTTY;
 383
 384         switch(cmd) {
 385         case DIOCGPART:
 386         {
 387                 struct partinfo *dpart;
 388                 u_int64_t size;
 389                 dpart = (void *)data;
 390                 bzero(dpart, sizeof(*dpart));
 391
 392                 if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL)
 393                         return ENODEV;
 394                 if (dmv->diskp->d_info.d_media_blksize == 0) {
 395                         dm_dev_unbusy(dmv);
 396                         return ENOTSUP;
 397                 } else {
 398                         size = dm_table_size(&dmv->table_head);
 399                         dpart->media_offset  = 0;
 400                         dpart->media_size    = size * DEV_BSIZE;
 401                         dpart->media_blocks  = size;
 402                         dpart->media_blksize = DEV_BSIZE;
 403                         dpart->fstype = FS_BSDFFS;
 404                 }
 405                 dm_dev_unbusy(dmv);
 406                 break;
 407         }
 408
 409         default:
 410                 aprint_debug("unknown disk_ioctl called\n");
 411                 return ENOTTY;
 412                 break; /* NOT REACHED */
 413         }
 414
 415         return 0;
 416 }
 417
 418 /*
 419  * Do all IO operations on dm logical devices.
 420  */
 421 static int
 422 dmstrategy(struct dev_strategy_args *ap)
 423 {
 424         cdev_t dev = ap->a_head.a_dev;
 425         struct bio *bio = ap->a_bio;
 426         struct buf *bp = bio->bio_buf;
 427         int bypass;
 428
 429         dm_dev_t *dmv;
 430         dm_table_t  *tbl;
 431         dm_table_entry_t *table_en;
 432         struct buf *nestbuf;
 433
 434         uint32_t dev_type;
 435
 436         uint64_t buf_start, buf_len, issued_len;
 437         uint64_t table_start, table_end;
 438         uint64_t start, end;
 439
 440         buf_start = bio->bio_offset;
 441         buf_len = bp->b_bcount;
 442
 443         tbl = NULL;
 444
 445         table_end = 0;
 446         dev_type = 0;
 447         issued_len = 0;
 448
 449         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL) {
 450                 bp->b_error = EIO;
 451                 bp->b_resid = bp->b_bcount;
 452                 biodone(bio);
 453                 return 0;
 454         }
 455
 456         switch(bp->b_cmd) {
 457         case BUF_CMD_READ:
 458         case BUF_CMD_WRITE:
 459         case BUF_CMD_FREEBLKS:
 460                 bypass = 0;
 461                 break;
 462         case BUF_CMD_FLUSH:
 463                 bypass = 1;
 464                 KKASSERT(buf_len == 0);
 465                 break;
 466         default:
 467                 dm_dev_unbusy(dmv);
 468                 bp->b_error = EIO;
 469                 bp->b_resid = bp->b_bcount;
 470                 biodone(bio);
 471                 return 0;
 472         }
 473
 474         if (bypass == 0 &&
 475             bounds_check_with_mediasize(bio, DEV_BSIZE,
 476                                         dm_table_size(&dmv->table_head)) <= 0) {
 477                 dm_dev_unbusy(dmv);
 478                 bp->b_resid = bp->b_bcount;
 479                 biodone(bio);
 480                 return 0;
 481         }
 482
 483         /* Select active table */
 484         tbl = dm_table_get_entry(&dmv->table_head, DM_TABLE_ACTIVE);
 485
 486         nestiobuf_init(bio);
 487         devstat_start_transaction(&dmv->stats);
 488
 489         /*
 490          * Find out what tables I want to select.
 491          */
 492         SLIST_FOREACH(table_en, tbl, next) {
 493                 /*
 494                  * I need need number of bytes not blocks.
 495                  */
 496                 table_start = table_en->start * DEV_BSIZE;
 497                 table_end = table_start + (table_en->length) * DEV_BSIZE;
 498
 499                 /*
 500                  * Calculate the start and end
 501                  */
 502                 start = MAX(table_start, buf_start);
 503                 end = MIN(table_end, buf_start + buf_len);
 504
 505                 aprint_debug("----------------------------------------\n");
 506                 aprint_debug("table_start %010" PRIu64", table_end %010"
 507                     PRIu64 "\n", table_start, table_end);
 508                 aprint_debug("buf_start %010" PRIu64", buf_len %010"
 509                     PRIu64"\n", buf_start, buf_len);
 510                 aprint_debug("start-buf_start %010"PRIu64", end %010"
 511                     PRIu64"\n", start - buf_start, end);
 512                 aprint_debug("start %010" PRIu64" , end %010"
 513                     PRIu64"\n", start, end);
 514                 aprint_debug("\n----------------------------------------\n");
 515
 516                 if (bypass) {
 517                         nestbuf = getpbuf(NULL);
 518                         nestbuf->b_flags |= bio->bio_buf->b_flags & B_HASBOGUS;
 519
 520                         nestiobuf_add(bio, nestbuf, 0, 0, &dmv->stats);
 521                         nestbuf->b_bio1.bio_offset = 0;
 522                         table_en->target->strategy(table_en, nestbuf);
 523                 } else if (start < end) {
 524                         nestbuf = getpbuf(NULL);
 525                         nestbuf->b_flags |= bio->bio_buf->b_flags & B_HASBOGUS;
 526
 527                         nestiobuf_add(bio, nestbuf,
 528                                       start - buf_start, (end - start),
 529                                       &dmv->stats);
 530                         issued_len += end - start;
 531
 532                         nestbuf->b_bio1.bio_offset = (start - table_start);
 533                         table_en->target->strategy(table_en, nestbuf);
 534                 }
 535         }
 536
 537         if (issued_len < buf_len)
 538                 nestiobuf_error(bio, EINVAL);
 539         nestiobuf_start(bio);
 540         dm_table_release(&dmv->table_head, DM_TABLE_ACTIVE);
 541         dm_dev_unbusy(dmv);
 542
 543         return 0;
 544 }
 545
 546 static int
 547 dmdump(struct dev_dump_args *ap)
 548 {
 549         cdev_t dev = ap->a_head.a_dev;
 550         dm_dev_t *dmv;
 551         dm_table_t  *tbl;
 552         dm_table_entry_t *table_en;
 553         uint32_t dev_type;
 554         uint64_t buf_start, buf_len, issued_len;
 555         uint64_t table_start, table_end;
 556         uint64_t start, end, data_offset;
 557         off_t offset;
 558         size_t length;
 559         int error = 0;
 560
 561         buf_start = ap->a_offset;
 562         buf_len = ap->a_length;
 563
 564         tbl = NULL;
 565
 566         table_end = 0;
 567         dev_type = 0;
 568         issued_len = 0;
 569
 570         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL) {
 571                 return EIO;
 572         }
 573
 574         /* Select active table */
 575         tbl = dm_table_get_entry(&dmv->table_head, DM_TABLE_ACTIVE);
 576
 577
 578         /*
 579          * Find out what tables I want to select.
 580          */
 581         SLIST_FOREACH(table_en, tbl, next) {
 582                 /*
 583                  * I need need number of bytes not blocks.
 584                  */
 585                 table_start = table_en->start * DEV_BSIZE;
 586                 table_end = table_start + (table_en->length) * DEV_BSIZE;
 587
 588                 /*
 589                  * Calculate the start and end
 590                  */
 591                 start = MAX(table_start, buf_start);
 592                 end = MIN(table_end, buf_start + buf_len);
 593
 594                 if (ap->a_length == 0) {
 595                         if (table_en->target->dump == NULL) {
 596                                 error = ENXIO;
 597                                 goto out;
 598                         }
 599
 600                         table_en->target->dump(table_en, NULL, 0, 0);
 601                 } else if (start < end) {
 602                         data_offset = start - buf_start;
 603                         offset = start - table_start;
 604                         length = end - start;
 605
 606                         if (table_en->target->dump == NULL) {
 607                                 error = ENXIO;
 608                                 goto out;
 609                         }
 610
 611                         table_en->target->dump(table_en,
 612                             (char *)ap->a_virtual + data_offset,
 613                             length, offset);
 614
 615                         issued_len += end - start;
 616                 }
 617         }
 618
 619         if (issued_len < buf_len)
 620                 error = EINVAL;
 621
 622 out:
 623         dm_table_release(&dmv->table_head, DM_TABLE_ACTIVE);
 624         dm_dev_unbusy(dmv);
 625
 626         return error;
 627 }
 628
 629 static int
 630 dmsize(struct dev_psize_args *ap)
 631 {
 632         cdev_t dev = ap->a_head.a_dev;
 633         dm_dev_t *dmv;
 634         uint64_t size;
 635
 636         size = 0;
 637
 638         if ((dmv = dm_dev_lookup(NULL, NULL, minor(dev))) == NULL)
 639                         return ENOENT;
 640
 641         size = dm_table_size(&dmv->table_head);
 642         dm_dev_unbusy(dmv);
 643
 644         ap->a_result = (int64_t)size;
 645
 646         return 0;
 647 }
 648
 649 #if 0
 650 static void
 651 dmminphys(struct buf *bp)
 652 {
 653
 654         bp->b_bcount = MIN(bp->b_bcount, MAXPHYS);
 655 }
 656 #endif
 657
 658 void
 659 dmsetdiskinfo(struct disk *disk, dm_table_head_t *head)
 660 {
 661         struct disk_info info;
 662         uint64_t dmp_size;
 663
 664         dmp_size = dm_table_size(head);
 665
 666         bzero(&info, sizeof(struct disk_info));
 667         info.d_media_blksize = DEV_BSIZE;
 668         info.d_media_blocks = dmp_size;
 669 #if 0
 670         /* this is set by disk_setdiskinfo */
 671         info.d_media_size = dmp_size * DEV_BSIZE;
 672 #endif
 673         info.d_dsflags = DSO_MBRQUIET | DSO_DEVICEMAPPER;
 674
 675         info.d_secpertrack = 32;
 676         info.d_nheads = 64;
 677         info.d_secpercyl = info.d_secpertrack * info.d_nheads;
 678         info.d_ncylinders = dmp_size / info.d_secpercyl;
 679
 680         disk_setdiskinfo(disk, &info);
 681 }
 682
 683 TUNABLE_INT("debug.dm_debug", &dm_debug_level);
 684 SYSCTL_INT(_debug, OID_AUTO, dm_debug, CTLFLAG_RW, &dm_debug_level,
 685                0, "Eanble device mapper debugging");
 686