sys/dev/xen/blkfront/blkfront.c

   1 /*
   2  * XenBSD block device driver
   3  *
   4  * Copyright (c) 2009 Scott Long, Yahoo!
   5  * Copyright (c) 2009 Frank Suchomel, Citrix
   6  * Copyright (c) 2009 Doug F. Rabson, Citrix
   7  * Copyright (c) 2005 Kip Macy
   8  * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
   9  * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
  10  *
  11  *
  12  * Permission is hereby granted, free of charge, to any person obtaining a copy
  13  * of this software and associated documentation files (the "Software"), to
  14  * deal in the Software without restriction, including without limitation the
  15  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  16  * sell copies of the Software, and to permit persons to whom the Software is
  17  * furnished to do so, subject to the following conditions:
  18  *
  19  * The above copyright notice and this permission notice shall be included in
  20  * all copies or substantial portions of the Software.
  21  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  22  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  23  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  24  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  25  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  26  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  27  * DEALINGS IN THE SOFTWARE.
  28  */
  29
  30 #include <sys/cdefs.h>
  31 __FBSDID("$FreeBSD$");
  32
  33 #include <sys/param.h>
  34 #include <sys/systm.h>
  35 #include <sys/malloc.h>
  36 #include <sys/kernel.h>
  37 #include <vm/vm.h>
  38 #include <vm/pmap.h>
  39
  40 #include <sys/bio.h>
  41 #include <sys/bus.h>
  42 #include <sys/conf.h>
  43 #include <sys/module.h>
  44
  45 #include <machine/bus.h>
  46 #include <sys/rman.h>
  47 #include <machine/resource.h>
  48 #include <machine/intr_machdep.h>
  49 #include <machine/vmparam.h>
  50 #include <sys/bus_dma.h>
  51
  52 #include <machine/_inttypes.h>
  53 #include <machine/xen/xen-os.h>
  54 #include <machine/xen/xenfunc.h>
  55
  56 #include <xen/hypervisor.h>
  57 #include <xen/xen_intr.h>
  58 #include <xen/evtchn.h>
  59 #include <xen/gnttab.h>
  60 #include <xen/interface/grant_table.h>
  61 #include <xen/interface/io/protocols.h>
  62 #include <xen/xenbus/xenbusvar.h>
  63
  64 #include <geom/geom_disk.h>
  65
  66 #include <dev/xen/blkfront/block.h>
  67
  68 #include "xenbus_if.h"
  69
  70 /* prototypes */
  71 static void xb_free_command(struct xb_command *cm);
  72 static void xb_startio(struct xb_softc *sc);
  73 static void blkfront_connect(struct xb_softc *);
  74 static void blkfront_closing(device_t);
  75 static int blkfront_detach(device_t);
  76 static int setup_blkring(struct xb_softc *);
  77 static void blkif_int(void *);
  78 static void blkfront_initialize(struct xb_softc *);
  79 #if 0
  80 static void blkif_recover(struct xb_softc *);
  81 #endif
  82 static int blkif_completion(struct xb_command *);
  83 static void blkif_free(struct xb_softc *, int);
  84 static void blkif_queue_cb(void *, bus_dma_segment_t *, int, int);
  85
  86 MALLOC_DEFINE(M_XENBLOCKFRONT, "xbd", "Xen Block Front driver data");
  87
  88 #define GRANT_INVALID_REF 0
  89
  90 /* Control whether runtime update of vbds is enabled. */
  91 #define ENABLE_VBD_UPDATE 0
  92
  93 #if ENABLE_VBD_UPDATE
  94 static void vbd_update(void);
  95 #endif
  96
  97 #define BLKIF_STATE_DISCONNECTED 0
  98 #define BLKIF_STATE_CONNECTED    1
  99 #define BLKIF_STATE_SUSPENDED    2
 100
 101 #ifdef notyet
 102 static char *blkif_state_name[] = {
 103         [BLKIF_STATE_DISCONNECTED] = "disconnected",
 104         [BLKIF_STATE_CONNECTED]    = "connected",
 105         [BLKIF_STATE_SUSPENDED]    = "closed",
 106 };
 107
 108 static char * blkif_status_name[] = {
 109         [BLKIF_INTERFACE_STATUS_CLOSED]       = "closed",
 110         [BLKIF_INTERFACE_STATUS_DISCONNECTED] = "disconnected",
 111         [BLKIF_INTERFACE_STATUS_CONNECTED]    = "connected",
 112         [BLKIF_INTERFACE_STATUS_CHANGED]      = "changed",
 113 };
 114 #endif
 115
 116 #if 0
 117 #define DPRINTK(fmt, args...) printf("[XEN] %s:%d: " fmt ".\n", __func__, __LINE__, ##args)
 118 #else
 119 #define DPRINTK(fmt, args...)
 120 #endif
 121
 122 static int blkif_open(struct disk *dp);
 123 static int blkif_close(struct disk *dp);
 124 static int blkif_ioctl(struct disk *dp, u_long cmd, void *addr, int flag, struct thread *td);
 125 static int blkif_queue_request(struct xb_softc *sc, struct xb_command *cm);
 126 static void xb_strategy(struct bio *bp);
 127
 128 // In order to quiesce the device during kernel dumps, outstanding requests to
 129 // DOM0 for disk reads/writes need to be accounted for.
 130 static  int     xb_dump(void *, void *, vm_offset_t, off_t, size_t);
 131
 132 /* XXX move to xb_vbd.c when VBD update support is added */
 133 #define MAX_VBDS 64
 134
 135 #define XBD_SECTOR_SIZE         512     /* XXX: assume for now */
 136 #define XBD_SECTOR_SHFT         9
 137
 138 /*
 139  * Translate Linux major/minor to an appropriate name and unit
 140  * number. For HVM guests, this allows us to use the same drive names
 141  * with blkfront as the emulated drives, easing transition slightly.
 142  */
 143 static void
 144 blkfront_vdevice_to_unit(int vdevice, int *unit, const char **name)
 145 {
 146         static struct vdev_info {
 147                 int major;
 148                 int shift;
 149                 int base;
 150                 const char *name;
 151         } info[] = {
 152                 {3,     6,      0,      "ad"},  /* ide0 */
 153                 {22,    6,      2,      "ad"},  /* ide1 */
 154                 {33,    6,      4,      "ad"},  /* ide2 */
 155                 {34,    6,      6,      "ad"},  /* ide3 */
 156                 {56,    6,      8,      "ad"},  /* ide4 */
 157                 {57,    6,      10,     "ad"},  /* ide5 */
 158                 {88,    6,      12,     "ad"},  /* ide6 */
 159                 {89,    6,      14,     "ad"},  /* ide7 */
 160                 {90,    6,      16,     "ad"},  /* ide8 */
 161                 {91,    6,      18,     "ad"},  /* ide9 */
 162
 163                 {8,     4,      0,      "da"},  /* scsi disk0 */
 164                 {65,    4,      16,     "da"},  /* scsi disk1 */
 165                 {66,    4,      32,     "da"},  /* scsi disk2 */
 166                 {67,    4,      48,     "da"},  /* scsi disk3 */
 167                 {68,    4,      64,     "da"},  /* scsi disk4 */
 168                 {69,    4,      80,     "da"},  /* scsi disk5 */
 169                 {70,    4,      96,     "da"},  /* scsi disk6 */
 170                 {71,    4,      112,    "da"},  /* scsi disk7 */
 171                 {128,   4,      128,    "da"},  /* scsi disk8 */
 172                 {129,   4,      144,    "da"},  /* scsi disk9 */
 173                 {130,   4,      160,    "da"},  /* scsi disk10 */
 174                 {131,   4,      176,    "da"},  /* scsi disk11 */
 175                 {132,   4,      192,    "da"},  /* scsi disk12 */
 176                 {133,   4,      208,    "da"},  /* scsi disk13 */
 177                 {134,   4,      224,    "da"},  /* scsi disk14 */
 178                 {135,   4,      240,    "da"},  /* scsi disk15 */
 179
 180                 {202,   4,      0,      "xbd"}, /* xbd */
 181
 182                 {0,     0,      0,      NULL},
 183         };
 184         int major = vdevice >> 8;
 185         int minor = vdevice & 0xff;
 186         int i;
 187
 188         if (vdevice & (1 << 28)) {
 189                 *unit = (vdevice & ((1 << 28) - 1)) >> 8;
 190                 *name = "xbd";
 191         }
 192
 193         for (i = 0; info[i].major; i++) {
 194                 if (info[i].major == major) {
 195                         *unit = info[i].base + (minor >> info[i].shift);
 196                         *name = info[i].name;
 197                         return;
 198                 }
 199         }
 200
 201         *unit = minor >> 4;
 202         *name = "xbd";
 203 }
 204
 205 int
 206 xlvbd_add(struct xb_softc *sc, blkif_sector_t sectors,
 207     int vdevice, uint16_t vdisk_info, unsigned long sector_size)
 208 {
 209         int     unit, error = 0;
 210         const char *name;
 211
 212         blkfront_vdevice_to_unit(vdevice, &unit, &name);
 213
 214         sc->xb_unit = unit;
 215
 216         if (strcmp(name, "xbd"))
 217                 device_printf(sc->xb_dev, "attaching as %s%d\n", name, unit);
 218
 219         sc->xb_disk = disk_alloc();
 220         sc->xb_disk->d_unit = sc->xb_unit;
 221         sc->xb_disk->d_open = blkif_open;
 222         sc->xb_disk->d_close = blkif_close;
 223         sc->xb_disk->d_ioctl = blkif_ioctl;
 224         sc->xb_disk->d_strategy = xb_strategy;
 225         sc->xb_disk->d_dump = xb_dump;
 226         sc->xb_disk->d_name = name;
 227         sc->xb_disk->d_drv1 = sc;
 228         sc->xb_disk->d_sectorsize = sector_size;
 229
 230         sc->xb_disk->d_mediasize = sectors * sector_size;
 231         sc->xb_disk->d_maxsize = sc->max_request_size;
 232         sc->xb_disk->d_flags = 0;
 233         disk_create(sc->xb_disk, DISK_VERSION_00);
 234
 235         return error;
 236 }
 237
 238 /************************ end VBD support *****************/
 239
 240 /*
 241  * Read/write routine for a buffer.  Finds the proper unit, place it on
 242  * the sortq and kick the controller.
 243  */
 244 static void
 245 xb_strategy(struct bio *bp)
 246 {
 247         struct xb_softc *sc = (struct xb_softc *)bp->bio_disk->d_drv1;
 248
 249         /* bogus disk? */
 250         if (sc == NULL) {
 251                 bp->bio_error = EINVAL;
 252                 bp->bio_flags |= BIO_ERROR;
 253                 bp->bio_resid = bp->bio_bcount;
 254                 biodone(bp);
 255                 return;
 256         }
 257
 258         /*
 259          * Place it in the queue of disk activities for this disk
 260          */
 261         mtx_lock(&sc->xb_io_lock);
 262
 263         xb_enqueue_bio(sc, bp);
 264         xb_startio(sc);
 265
 266         mtx_unlock(&sc->xb_io_lock);
 267         return;
 268 }
 269
 270 static void
 271 xb_bio_complete(struct xb_softc *sc, struct xb_command *cm)
 272 {
 273         struct bio *bp;
 274
 275         bp = cm->bp;
 276
 277         if ( unlikely(cm->status != BLKIF_RSP_OKAY) ) {
 278                 disk_err(bp, "disk error" , -1, 0);
 279                 printf(" status: %x\n", cm->status);
 280                 bp->bio_flags |= BIO_ERROR;
 281         }
 282
 283         if (bp->bio_flags & BIO_ERROR)
 284                 bp->bio_error = EIO;
 285         else
 286                 bp->bio_resid = 0;
 287
 288         xb_free_command(cm);
 289         biodone(bp);
 290 }
 291
 292 // Quiesce the disk writes for a dump file before allowing the next buffer.
 293 static void
 294 xb_quiesce(struct xb_softc *sc)
 295 {
 296         int             mtd;
 297
 298         // While there are outstanding requests
 299         while (!TAILQ_EMPTY(&sc->cm_busy)) {
 300                 RING_FINAL_CHECK_FOR_RESPONSES(&sc->ring, mtd);
 301                 if (mtd) {
 302                         /* Recieved request completions, update queue. */
 303                         blkif_int(sc);
 304                 }
 305                 if (!TAILQ_EMPTY(&sc->cm_busy)) {
 306                         /*
 307                          * Still pending requests, wait for the disk i/o
 308                          * to complete.
 309                          */
 310                         HYPERVISOR_yield();
 311                 }
 312         }
 313 }
 314
 315 /* Kernel dump function for a paravirtualized disk device */
 316 static void
 317 xb_dump_complete(struct xb_command *cm)
 318 {
 319
 320         xb_enqueue_complete(cm);
 321 }
 322
 323 static int
 324 xb_dump(void *arg, void *virtual, vm_offset_t physical, off_t offset,
 325         size_t length)
 326 {
 327         struct  disk    *dp = arg;
 328         struct xb_softc *sc = (struct xb_softc *) dp->d_drv1;
 329         struct xb_command *cm;
 330         size_t          chunk;
 331         int             sbp;
 332         int             rc = 0;
 333
 334         if (length <= 0)
 335                 return (rc);
 336
 337         xb_quiesce(sc); /* All quiet on the western front. */
 338
 339         /*
 340          * If this lock is held, then this module is failing, and a
 341          * successful kernel dump is highly unlikely anyway.
 342          */
 343         mtx_lock(&sc->xb_io_lock);
 344
 345         /* Split the 64KB block as needed */
 346         for (sbp=0; length > 0; sbp++) {
 347                 cm = xb_dequeue_free(sc);
 348                 if (cm == NULL) {
 349                         mtx_unlock(&sc->xb_io_lock);
 350                         device_printf(sc->xb_dev, "dump: no more commands?\n");
 351                         return (EBUSY);
 352                 }
 353
 354                 if (gnttab_alloc_grant_references(sc->max_request_segments,
 355                                                   &cm->gref_head) != 0) {
 356                         xb_free_command(cm);
 357                         mtx_unlock(&sc->xb_io_lock);
 358                         device_printf(sc->xb_dev, "no more grant allocs?\n");
 359                         return (EBUSY);
 360                 }
 361
 362                 chunk = length > sc->max_request_size
 363                       ? sc->max_request_size : length;
 364                 cm->data = virtual;
 365                 cm->datalen = chunk;
 366                 cm->operation = BLKIF_OP_WRITE;
 367                 cm->sector_number = offset / dp->d_sectorsize;
 368                 cm->cm_complete = xb_dump_complete;
 369
 370                 xb_enqueue_ready(cm);
 371
 372                 length -= chunk;
 373                 offset += chunk;
 374                 virtual = (char *) virtual + chunk;
 375         }
 376
 377         /* Tell DOM0 to do the I/O */
 378         xb_startio(sc);
 379         mtx_unlock(&sc->xb_io_lock);
 380
 381         /* Poll for the completion. */
 382         xb_quiesce(sc); /* All quite on the eastern front */
 383
 384         /* If there were any errors, bail out... */
 385         while ((cm = xb_dequeue_complete(sc)) != NULL) {
 386                 if (cm->status != BLKIF_RSP_OKAY) {
 387                         device_printf(sc->xb_dev,
 388                             "Dump I/O failed at sector %jd\n",
 389                             cm->sector_number);
 390                         rc = EIO;
 391                 }
 392                 xb_free_command(cm);
 393         }
 394
 395         return (rc);
 396 }
 397
 398
 399 static int
 400 blkfront_probe(device_t dev)
 401 {
 402
 403         if (!strcmp(xenbus_get_type(dev), "vbd")) {
 404                 device_set_desc(dev, "Virtual Block Device");
 405                 device_quiet(dev);
 406                 return (0);
 407         }
 408
 409         return (ENXIO);
 410 }
 411
 412 /*
 413  * Setup supplies the backend dir, virtual device.  We place an event
 414  * channel and shared frame entries.  We watch backend to wait if it's
 415  * ok.
 416  */
 417 static int
 418 blkfront_attach(device_t dev)
 419 {
 420         struct xb_softc *sc;
 421         const char *name;
 422         int error;
 423         int vdevice;
 424         int i;
 425         int unit;
 426
 427         /* FIXME: Use dynamic device id if this is not set. */
 428         error = xs_scanf(XST_NIL, xenbus_get_node(dev),
 429             "virtual-device", NULL, "%i", &vdevice);
 430         if (error) {
 431                 xenbus_dev_fatal(dev, error, "reading virtual-device");
 432                 device_printf(dev, "Couldn't determine virtual device.\n");
 433                 return (error);
 434         }
 435
 436         blkfront_vdevice_to_unit(vdevice, &unit, &name);
 437         if (!strcmp(name, "xbd"))
 438                 device_set_unit(dev, unit);
 439
 440         sc = device_get_softc(dev);
 441         mtx_init(&sc->xb_io_lock, "blkfront i/o lock", NULL, MTX_DEF);
 442         xb_initq_free(sc);
 443         xb_initq_busy(sc);
 444         xb_initq_ready(sc);
 445         xb_initq_complete(sc);
 446         xb_initq_bio(sc);
 447         for (i = 0; i < XBF_MAX_RING_PAGES; i++)
 448                 sc->ring_ref[i] = GRANT_INVALID_REF;
 449
 450         sc->xb_dev = dev;
 451         sc->vdevice = vdevice;
 452         sc->connected = BLKIF_STATE_DISCONNECTED;
 453
 454         /* Front end dir is a number, which is used as the id. */
 455         sc->handle = strtoul(strrchr(xenbus_get_node(dev),'/')+1, NULL, 0);
 456
 457         /* Wait for backend device to publish its protocol capabilities. */
 458         xenbus_set_state(dev, XenbusStateInitialising);
 459
 460         return (0);
 461 }
 462
 463 static int
 464 blkfront_suspend(device_t dev)
 465 {
 466         struct xb_softc *sc = device_get_softc(dev);
 467
 468         /* Prevent new requests being issued until we fix things up. */
 469         mtx_lock(&sc->xb_io_lock);
 470         sc->connected = BLKIF_STATE_SUSPENDED;
 471         mtx_unlock(&sc->xb_io_lock);
 472
 473         return (0);
 474 }
 475
 476 static int
 477 blkfront_resume(device_t dev)
 478 {
 479 #if 0
 480         struct xb_softc *sc = device_get_softc(dev);
 481
 482         DPRINTK("blkfront_resume: %s\n", xenbus_get_node(dev));
 483
 484 /* XXX This can't work!!! */
 485         blkif_free(sc, 1);
 486         blkfront_initialize(sc);
 487         if (sc->connected == BLKIF_STATE_SUSPENDED)
 488                 blkif_recover(sc);
 489 #endif
 490         return (0);
 491 }
 492
 493 static void
 494 blkfront_initialize(struct xb_softc *sc)
 495 {
 496         const char *otherend_path;
 497         const char *node_path;
 498         int error;
 499         int i;
 500
 501         if (xenbus_get_state(sc->xb_dev) != XenbusStateInitialising)
 502                 return;
 503
 504         /*
 505          * Protocol defaults valid even if negotiation for a
 506          * setting fails.
 507          */
 508         sc->ring_pages = 1;
 509         sc->max_requests = BLKIF_MAX_RING_REQUESTS(PAGE_SIZE);
 510         sc->max_request_segments = BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK;
 511         sc->max_request_size = (sc->max_request_segments - 1) * PAGE_SIZE;
 512         sc->max_request_blocks = BLKIF_SEGS_TO_BLOCKS(sc->max_request_segments);
 513
 514         /*
 515          * Protocol negotiation.
 516          *
 517          * \note xs_gather() returns on the first encountered error, so
 518          *       we must use independant calls in order to guarantee
 519          *       we don't miss information in a sparsly populated back-end
 520          *       tree.
 521          */
 522         otherend_path = xenbus_get_otherend_path(sc->xb_dev);
 523         node_path = xenbus_get_node(sc->xb_dev);
 524         (void)xs_scanf(XST_NIL, otherend_path,
 525                        "max-ring-pages", NULL, "%" PRIu32,
 526                        &sc->ring_pages);
 527
 528         (void)xs_scanf(XST_NIL, otherend_path,
 529                        "max-requests", NULL, "%" PRIu32,
 530                        &sc->max_requests);
 531
 532         (void)xs_scanf(XST_NIL, otherend_path,
 533                        "max-request-segments", NULL, "%" PRIu32,
 534                        &sc->max_request_segments);
 535
 536         (void)xs_scanf(XST_NIL, otherend_path,
 537                        "max-request-size", NULL, "%" PRIu32,
 538                        &sc->max_request_size);
 539
 540         if (sc->ring_pages > XBF_MAX_RING_PAGES) {
 541                 device_printf(sc->xb_dev, "Back-end specified ring-pages of "
 542                               "%u limited to front-end limit of %zu.\n",
 543                               sc->ring_pages, XBF_MAX_RING_PAGES);
 544                 sc->ring_pages = XBF_MAX_RING_PAGES;
 545         }
 546
 547         if (sc->max_requests > XBF_MAX_REQUESTS) {
 548                 device_printf(sc->xb_dev, "Back-end specified max_requests of "
 549                               "%u limited to front-end limit of %u.\n",
 550                               sc->max_requests, XBF_MAX_REQUESTS);
 551                 sc->max_requests = XBF_MAX_REQUESTS;
 552         }
 553
 554         if (sc->max_request_segments > XBF_MAX_SEGMENTS_PER_REQUEST) {
 555                 device_printf(sc->xb_dev, "Back-end specificed "
 556                               "max_requests_segments of %u limited to "
 557                               "front-end limit of %u.\n",
 558                               sc->max_request_segments,
 559                               XBF_MAX_SEGMENTS_PER_REQUEST);
 560                 sc->max_request_segments = XBF_MAX_SEGMENTS_PER_REQUEST;
 561         }
 562
 563         if (sc->max_request_size > XBF_MAX_REQUEST_SIZE) {
 564                 device_printf(sc->xb_dev, "Back-end specificed "
 565                               "max_request_size of %u limited to front-end "
 566                               "limit of %u.\n", sc->max_request_size,
 567                               XBF_MAX_REQUEST_SIZE);
 568                 sc->max_request_size = XBF_MAX_REQUEST_SIZE;
 569         }
 570         sc->max_request_blocks = BLKIF_SEGS_TO_BLOCKS(sc->max_request_segments);
 571
 572         /* Allocate datastructures based on negotiated values. */
 573         error = bus_dma_tag_create(NULL,                /* parent */
 574                                    512, PAGE_SIZE,      /* algnmnt, boundary */
 575                                    BUS_SPACE_MAXADDR,   /* lowaddr */
 576                                    BUS_SPACE_MAXADDR,   /* highaddr */
 577                                    NULL, NULL,          /* filter, filterarg */
 578                                    sc->max_request_size,
 579                                    sc->max_request_segments,
 580                                    PAGE_SIZE,           /* maxsegsize */
 581                                    BUS_DMA_ALLOCNOW,    /* flags */
 582                                    busdma_lock_mutex,   /* lockfunc */
 583                                    &sc->xb_io_lock,     /* lockarg */
 584                                    &sc->xb_io_dmat);
 585         if (error != 0) {
 586                 xenbus_dev_fatal(sc->xb_dev, error,
 587                                  "Cannot allocate parent DMA tag\n");
 588                 return;
 589         }
 590
 591         /* Per-transaction data allocation. */
 592         sc->shadow = malloc(sizeof(*sc->shadow) * sc->max_requests,
 593                             M_XENBLOCKFRONT, M_NOWAIT|M_ZERO);
 594         if (sc->shadow == NULL) {
 595                 xenbus_dev_fatal(sc->xb_dev, error,
 596                                  "Cannot allocate request structures\n");
 597         }
 598
 599         for (i = 0; i < sc->max_requests; i++) {
 600                 struct xb_command *cm;
 601
 602                 cm = &sc->shadow[i];
 603                 cm->sg_refs = malloc(sizeof(grant_ref_t)
 604                                    * sc->max_request_segments,
 605                                      M_XENBLOCKFRONT, M_NOWAIT);
 606                 if (cm->sg_refs == NULL)
 607                         break;
 608                 cm->id = i;
 609                 cm->cm_sc = sc;
 610                 if (bus_dmamap_create(sc->xb_io_dmat, 0, &cm->map) != 0)
 611                         break;
 612                 xb_free_command(cm);
 613         }
 614
 615         if (setup_blkring(sc) != 0)
 616                 return;
 617
 618         error = xs_printf(XST_NIL, node_path,
 619                          "ring-pages","%u", sc->ring_pages);
 620         if (error) {
 621                 xenbus_dev_fatal(sc->xb_dev, error,
 622                                  "writing %s/ring-pages",
 623                                  node_path);
 624                 return;
 625         }
 626
 627         error = xs_printf(XST_NIL, node_path,
 628                          "max-requests","%u", sc->max_requests);
 629         if (error) {
 630                 xenbus_dev_fatal(sc->xb_dev, error,
 631                                  "writing %s/max-requests",
 632                                  node_path);
 633                 return;
 634         }
 635
 636         error = xs_printf(XST_NIL, node_path,
 637                          "max-request-segments","%u", sc->max_request_segments);
 638         if (error) {
 639                 xenbus_dev_fatal(sc->xb_dev, error,
 640                                  "writing %s/max-request-segments",
 641                                  node_path);
 642                 return;
 643         }
 644
 645         error = xs_printf(XST_NIL, node_path,
 646                          "max-request-size","%u", sc->max_request_size);
 647         if (error) {
 648                 xenbus_dev_fatal(sc->xb_dev, error,
 649                                  "writing %s/max-request-size",
 650                                  node_path);
 651                 return;
 652         }
 653
 654         error = xs_printf(XST_NIL, node_path, "event-channel",
 655                           "%u", irq_to_evtchn_port(sc->irq));
 656         if (error) {
 657                 xenbus_dev_fatal(sc->xb_dev, error,
 658                                  "writing %s/event-channel",
 659                                  node_path);
 660                 return;
 661         }
 662
 663         error = xs_printf(XST_NIL, node_path,
 664                           "protocol", "%s", XEN_IO_PROTO_ABI_NATIVE);
 665         if (error) {
 666                 xenbus_dev_fatal(sc->xb_dev, error,
 667                                  "writing %s/protocol",
 668                                  node_path);
 669                 return;
 670         }
 671
 672         xenbus_set_state(sc->xb_dev, XenbusStateInitialised);
 673 }
 674
 675 static int
 676 setup_blkring(struct xb_softc *sc)
 677 {
 678         blkif_sring_t *sring;
 679         uintptr_t sring_page_addr;
 680         int error;
 681         int i;
 682
 683         sring = malloc(sc->ring_pages * PAGE_SIZE, M_XENBLOCKFRONT,
 684                        M_NOWAIT|M_ZERO);
 685         if (sring == NULL) {
 686                 xenbus_dev_fatal(sc->xb_dev, ENOMEM, "allocating shared ring");
 687                 return (ENOMEM);
 688         }
 689         SHARED_RING_INIT(sring);
 690         FRONT_RING_INIT(&sc->ring, sring, sc->ring_pages * PAGE_SIZE);
 691
 692         for (i = 0, sring_page_addr = (uintptr_t)sring;
 693              i < sc->ring_pages;
 694              i++, sring_page_addr += PAGE_SIZE) {
 695
 696                 error = xenbus_grant_ring(sc->xb_dev,
 697                     (vtomach(sring_page_addr) >> PAGE_SHIFT), &sc->ring_ref[i]);
 698                 if (error) {
 699                         xenbus_dev_fatal(sc->xb_dev, error,
 700                                          "granting ring_ref(%d)", i);
 701                         return (error);
 702                 }
 703         }
 704         error = xs_printf(XST_NIL, xenbus_get_node(sc->xb_dev),
 705                           "ring-ref","%u", sc->ring_ref[0]);
 706         if (error) {
 707                 xenbus_dev_fatal(sc->xb_dev, error, "writing %s/ring-ref",
 708                                  xenbus_get_node(sc->xb_dev));
 709                 return (error);
 710         }
 711         for (i = 1; i < sc->ring_pages; i++) {
 712                 char ring_ref_name[]= "ring_refXX";
 713
 714                 snprintf(ring_ref_name, sizeof(ring_ref_name), "ring-ref%u", i);
 715                 error = xs_printf(XST_NIL, xenbus_get_node(sc->xb_dev),
 716                                  ring_ref_name, "%u", sc->ring_ref[i]);
 717                 if (error) {
 718                         xenbus_dev_fatal(sc->xb_dev, error, "writing %s/%s",
 719                                          xenbus_get_node(sc->xb_dev),
 720                                          ring_ref_name);
 721                         return (error);
 722                 }
 723         }
 724
 725         error = bind_listening_port_to_irqhandler(
 726             xenbus_get_otherend_id(sc->xb_dev),
 727             "xbd", (driver_intr_t *)blkif_int, sc,
 728             INTR_TYPE_BIO | INTR_MPSAFE, &sc->irq);
 729         if (error) {
 730                 xenbus_dev_fatal(sc->xb_dev, error,
 731                     "bind_evtchn_to_irqhandler failed");
 732                 return (error);
 733         }
 734
 735         return (0);
 736 }
 737
 738 /**
 739  * Callback received when the backend's state changes.
 740  */
 741 static int
 742 blkfront_backend_changed(device_t dev, XenbusState backend_state)
 743 {
 744         struct xb_softc *sc = device_get_softc(dev);
 745
 746         DPRINTK("backend_state=%d\n", backend_state);
 747
 748         switch (backend_state) {
 749         case XenbusStateUnknown:
 750         case XenbusStateInitialising:
 751         case XenbusStateReconfigured:
 752         case XenbusStateReconfiguring:
 753         case XenbusStateClosed:
 754                 break;
 755
 756         case XenbusStateInitWait:
 757                 blkfront_initialize(sc);
 758                 break;
 759
 760         case XenbusStateInitialised:
 761         case XenbusStateConnected:
 762                 blkfront_initialize(sc);
 763                 blkfront_connect(sc);
 764                 break;
 765
 766         case XenbusStateClosing:
 767                 if (sc->users > 0)
 768                         xenbus_dev_error(dev, -EBUSY,
 769                                          "Device in use; refusing to close");
 770                 else
 771                         blkfront_closing(dev);
 772                 break;
 773         }
 774
 775         return (0);
 776 }
 777
 778 /*
 779 ** Invoked when the backend is finally 'ready' (and has told produced
 780 ** the details about the physical device - #sectors, size, etc).
 781 */
 782 static void
 783 blkfront_connect(struct xb_softc *sc)
 784 {
 785         device_t dev = sc->xb_dev;
 786         unsigned long sectors, sector_size;
 787         unsigned int binfo;
 788         int err, feature_barrier;
 789
 790         if( (sc->connected == BLKIF_STATE_CONNECTED) ||
 791             (sc->connected == BLKIF_STATE_SUSPENDED) )
 792                 return;
 793
 794         DPRINTK("blkfront.c:connect:%s.\n", xenbus_get_otherend_path(dev));
 795
 796         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
 797                         "sectors", "%lu", &sectors,
 798                         "info", "%u", &binfo,
 799                         "sector-size", "%lu", &sector_size,
 800                         NULL);
 801         if (err) {
 802                 xenbus_dev_fatal(dev, err,
 803                     "reading backend fields at %s",
 804                     xenbus_get_otherend_path(dev));
 805                 return;
 806         }
 807         err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
 808                         "feature-barrier", "%lu", &feature_barrier,
 809                         NULL);
 810         if (!err || feature_barrier)
 811                 sc->xb_flags |= XB_BARRIER;
 812
 813         device_printf(dev, "%juMB <%s> at %s",
 814             (uintmax_t) sectors / (1048576 / sector_size),
 815             device_get_desc(dev),
 816             xenbus_get_node(dev));
 817         bus_print_child_footer(device_get_parent(dev), dev);
 818
 819         xlvbd_add(sc, sectors, sc->vdevice, binfo, sector_size);
 820
 821         (void)xenbus_set_state(dev, XenbusStateConnected);
 822
 823         /* Kick pending requests. */
 824         mtx_lock(&sc->xb_io_lock);
 825         sc->connected = BLKIF_STATE_CONNECTED;
 826         xb_startio(sc);
 827         sc->xb_flags |= XB_READY;
 828         mtx_unlock(&sc->xb_io_lock);
 829
 830 }
 831
 832 /**
 833  * Handle the change of state of the backend to Closing.  We must delete our
 834  * device-layer structures now, to ensure that writes are flushed through to
 835  * the backend.  Once this is done, we can switch to Closed in
 836  * acknowledgement.
 837  */
 838 static void
 839 blkfront_closing(device_t dev)
 840 {
 841         struct xb_softc *sc = device_get_softc(dev);
 842
 843         xenbus_set_state(dev, XenbusStateClosing);
 844
 845         DPRINTK("blkfront_closing: %s removed\n", xenbus_get_node(dev));
 846
 847         if (sc->xb_disk != NULL) {
 848                 disk_destroy(sc->xb_disk);
 849                 sc->xb_disk = NULL;
 850         }
 851
 852         xenbus_set_state(dev, XenbusStateClosed);
 853 }
 854
 855
 856 static int
 857 blkfront_detach(device_t dev)
 858 {
 859         struct xb_softc *sc = device_get_softc(dev);
 860
 861         DPRINTK("blkfront_remove: %s removed\n", xenbus_get_node(dev));
 862
 863         blkif_free(sc, 0);
 864         mtx_destroy(&sc->xb_io_lock);
 865
 866         return 0;
 867 }
 868
 869
 870 static inline void
 871 flush_requests(struct xb_softc *sc)
 872 {
 873         int notify;
 874
 875         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&sc->ring, notify);
 876
 877         if (notify)
 878                 notify_remote_via_irq(sc->irq);
 879 }
 880
 881 static void
 882 blkif_restart_queue_callback(void *arg)
 883 {
 884         struct xb_softc *sc = arg;
 885
 886         mtx_lock(&sc->xb_io_lock);
 887
 888         xb_startio(sc);
 889
 890         mtx_unlock(&sc->xb_io_lock);
 891 }
 892
 893 static int
 894 blkif_open(struct disk *dp)
 895 {
 896         struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
 897
 898         if (sc == NULL) {
 899                 printf("xb%d: not found", sc->xb_unit);
 900                 return (ENXIO);
 901         }
 902
 903         sc->xb_flags |= XB_OPEN;
 904         sc->users++;
 905         return (0);
 906 }
 907
 908 static int
 909 blkif_close(struct disk *dp)
 910 {
 911         struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
 912
 913         if (sc == NULL)
 914                 return (ENXIO);
 915         sc->xb_flags &= ~XB_OPEN;
 916         if (--(sc->users) == 0) {
 917                 /* Check whether we have been instructed to close.  We will
 918                    have ignored this request initially, as the device was
 919                    still mounted. */
 920                 device_t dev = sc->xb_dev;
 921                 XenbusState state =
 922                         xenbus_read_driver_state(xenbus_get_otherend_path(dev));
 923
 924                 if (state == XenbusStateClosing)
 925                         blkfront_closing(dev);
 926         }
 927         return (0);
 928 }
 929
 930 static int
 931 blkif_ioctl(struct disk *dp, u_long cmd, void *addr, int flag, struct thread *td)
 932 {
 933         struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
 934
 935         if (sc == NULL)
 936                 return (ENXIO);
 937
 938         return (ENOTTY);
 939 }
 940
 941 static void
 942 xb_free_command(struct xb_command *cm)
 943 {
 944
 945         KASSERT((cm->cm_flags & XB_ON_XBQ_MASK) == 0,
 946             ("Freeing command that is still on a queue\n"));
 947
 948         cm->cm_flags = 0;
 949         cm->bp = NULL;
 950         cm->cm_complete = NULL;
 951         xb_enqueue_free(cm);
 952 }
 953
 954 /*
 955  * blkif_queue_request
 956  *
 957  * request block io
 958  *
 959  * id: for guest use only.
 960  * operation: BLKIF_OP_{READ,WRITE,PROBE}
 961  * buffer: buffer to read/write into. this should be a
 962  *   virtual address in the guest os.
 963  */
 964 static struct xb_command *
 965 xb_bio_command(struct xb_softc *sc)
 966 {
 967         struct xb_command *cm;
 968         struct bio *bp;
 969
 970         if (unlikely(sc->connected != BLKIF_STATE_CONNECTED))
 971                 return (NULL);
 972
 973         bp = xb_dequeue_bio(sc);
 974         if (bp == NULL)
 975                 return (NULL);
 976
 977         if ((cm = xb_dequeue_free(sc)) == NULL) {
 978                 xb_requeue_bio(sc, bp);
 979                 return (NULL);
 980         }
 981
 982         if (gnttab_alloc_grant_references(sc->max_request_segments,
 983             &cm->gref_head) != 0) {
 984                 gnttab_request_free_callback(&sc->callback,
 985                         blkif_restart_queue_callback, sc,
 986                         sc->max_request_segments);
 987                 xb_requeue_bio(sc, bp);
 988                 xb_enqueue_free(cm);
 989                 sc->xb_flags |= XB_FROZEN;
 990                 return (NULL);
 991         }
 992
 993         cm->bp = bp;
 994         cm->data = bp->bio_data;
 995         cm->datalen = bp->bio_bcount;
 996         cm->operation = (bp->bio_cmd == BIO_READ) ? BLKIF_OP_READ :
 997             BLKIF_OP_WRITE;
 998         cm->sector_number = (blkif_sector_t)bp->bio_pblkno;
 999
1000         return (cm);
1001 }
1002
1003 static int
1004 blkif_queue_request(struct xb_softc *sc, struct xb_command *cm)
1005 {
1006         int     error;
1007
1008         error = bus_dmamap_load(sc->xb_io_dmat, cm->map, cm->data, cm->datalen,
1009             blkif_queue_cb, cm, 0);
1010         if (error == EINPROGRESS) {
1011                 printf("EINPROGRESS\n");
1012                 sc->xb_flags |= XB_FROZEN;
1013                 cm->cm_flags |= XB_CMD_FROZEN;
1014                 return (0);
1015         }
1016
1017         return (error);
1018 }
1019
1020 static void
1021 blkif_queue_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
1022 {
1023         struct xb_softc *sc;
1024         struct xb_command *cm;
1025         blkif_request_t *ring_req;
1026         struct blkif_request_segment *sg;
1027         struct blkif_request_segment *last_block_sg;
1028         grant_ref_t *sg_ref;
1029         vm_paddr_t buffer_ma;
1030         uint64_t fsect, lsect;
1031         int ref;
1032         int op;
1033         int block_segs;
1034
1035         cm = arg;
1036         sc = cm->cm_sc;
1037
1038 //printf("%s: Start\n", __func__);
1039         if (error) {
1040                 printf("error %d in blkif_queue_cb\n", error);
1041                 cm->bp->bio_error = EIO;
1042                 biodone(cm->bp);
1043                 xb_free_command(cm);
1044                 return;
1045         }
1046
1047         /* Fill out a communications ring structure. */
1048         ring_req = RING_GET_REQUEST(&sc->ring, sc->ring.req_prod_pvt);
1049         sc->ring.req_prod_pvt++;
1050         ring_req->id = cm->id;
1051         ring_req->operation = cm->operation;
1052         ring_req->sector_number = cm->sector_number;
1053         ring_req->handle = (blkif_vdev_t)(uintptr_t)sc->xb_disk;
1054         ring_req->nr_segments = nsegs;
1055         cm->nseg = nsegs;
1056
1057         block_segs    = MIN(nsegs, BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK);
1058         sg            = ring_req->seg;
1059         last_block_sg = sg + block_segs;
1060         sg_ref        = cm->sg_refs;
1061
1062         while (1) {
1063
1064                 while (sg < last_block_sg) {
1065                         buffer_ma = segs->ds_addr;
1066                         fsect = (buffer_ma & PAGE_MASK) >> XBD_SECTOR_SHFT;
1067                         lsect = fsect + (segs->ds_len  >> XBD_SECTOR_SHFT) - 1;
1068
1069                         KASSERT(lsect <= 7, ("XEN disk driver data cannot "
1070                                 "cross a page boundary"));
1071
1072                         /* install a grant reference. */
1073                         ref = gnttab_claim_grant_reference(&cm->gref_head);
1074
1075                         /*
1076                          * GNTTAB_LIST_END == 0xffffffff, but it is private
1077                          * to gnttab.c.
1078                          */
1079                         KASSERT(ref != ~0, ("grant_reference failed"));
1080
1081                         gnttab_grant_foreign_access_ref(
1082                                 ref,
1083                                 xenbus_get_otherend_id(sc->xb_dev),
1084                                 buffer_ma >> PAGE_SHIFT,
1085                                 ring_req->operation == BLKIF_OP_WRITE);
1086
1087                         *sg_ref = ref;
1088                         *sg = (struct blkif_request_segment) {
1089                                 .gref       = ref,
1090                                 .first_sect = fsect,
1091                                 .last_sect  = lsect };
1092                         sg++;
1093                         sg_ref++;
1094                         segs++;
1095                         nsegs--;
1096                 }
1097                 block_segs = MIN(nsegs, BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK);
1098                 if (block_segs == 0)
1099                         break;
1100
1101                 sg = BLKRING_GET_SG_REQUEST(&sc->ring, sc->ring.req_prod_pvt);
1102                 sc->ring.req_prod_pvt++;
1103                 last_block_sg = sg + block_segs;
1104         }
1105
1106         if (cm->operation == BLKIF_OP_READ)
1107                 op = BUS_DMASYNC_PREREAD;
1108         else if (cm->operation == BLKIF_OP_WRITE)
1109                 op = BUS_DMASYNC_PREWRITE;
1110         else
1111                 op = 0;
1112         bus_dmamap_sync(sc->xb_io_dmat, cm->map, op);
1113
1114         gnttab_free_grant_references(cm->gref_head);
1115
1116         xb_enqueue_busy(cm);
1117
1118         /*
1119          * This flag means that we're probably executing in the busdma swi
1120          * instead of in the startio context, so an explicit flush is needed.
1121          */
1122         if (cm->cm_flags & XB_CMD_FROZEN)
1123                 flush_requests(sc);
1124
1125 //printf("%s: Done\n", __func__);
1126         return;
1127 }
1128
1129 /*
1130  * Dequeue buffers and place them in the shared communication ring.
1131  * Return when no more requests can be accepted or all buffers have
1132  * been queued.
1133  *
1134  * Signal XEN once the ring has been filled out.
1135  */
1136 static void
1137 xb_startio(struct xb_softc *sc)
1138 {
1139         struct xb_command *cm;
1140         int error, queued = 0;
1141
1142         mtx_assert(&sc->xb_io_lock, MA_OWNED);
1143
1144         while (RING_FREE_REQUESTS(&sc->ring) >= sc->max_request_blocks) {
1145                 if (sc->xb_flags & XB_FROZEN)
1146                         break;
1147
1148                 cm = xb_dequeue_ready(sc);
1149
1150                 if (cm == NULL)
1151                     cm = xb_bio_command(sc);
1152
1153                 if (cm == NULL)
1154                         break;
1155
1156                 if ((error = blkif_queue_request(sc, cm)) != 0) {
1157                         printf("blkif_queue_request returned %d\n", error);
1158                         break;
1159                 }
1160                 queued++;
1161         }
1162
1163         if (queued != 0)
1164                 flush_requests(sc);
1165 }
1166
1167 static void
1168 blkif_int(void *xsc)
1169 {
1170         struct xb_softc *sc = xsc;
1171         struct xb_command *cm;
1172         blkif_response_t *bret;
1173         RING_IDX i, rp;
1174         int op;
1175
1176         mtx_lock(&sc->xb_io_lock);
1177
1178         if (unlikely(sc->connected != BLKIF_STATE_CONNECTED)) {
1179                 mtx_unlock(&sc->xb_io_lock);
1180                 return;
1181         }
1182
1183  again:
1184         rp = sc->ring.sring->rsp_prod;
1185         rmb(); /* Ensure we see queued responses up to 'rp'. */
1186
1187         for (i = sc->ring.rsp_cons; i != rp;) {
1188                 bret = RING_GET_RESPONSE(&sc->ring, i);
1189                 cm   = &sc->shadow[bret->id];
1190
1191                 xb_remove_busy(cm);
1192                 i += blkif_completion(cm);
1193
1194                 if (cm->operation == BLKIF_OP_READ)
1195                         op = BUS_DMASYNC_POSTREAD;
1196                 else if (cm->operation == BLKIF_OP_WRITE)
1197                         op = BUS_DMASYNC_POSTWRITE;
1198                 else
1199                         op = 0;
1200                 bus_dmamap_sync(sc->xb_io_dmat, cm->map, op);
1201                 bus_dmamap_unload(sc->xb_io_dmat, cm->map);
1202
1203                 /*
1204                  * If commands are completing then resources are probably
1205                  * being freed as well.  It's a cheap assumption even when
1206                  * wrong.
1207                  */
1208                 sc->xb_flags &= ~XB_FROZEN;
1209
1210                 /*
1211                  * Directly call the i/o complete routine to save an
1212                  * an indirection in the common case.
1213                  */
1214                 cm->status = bret->status;
1215                 if (cm->bp)
1216                         xb_bio_complete(sc, cm);
1217                 else if (cm->cm_complete)
1218                         (cm->cm_complete)(cm);
1219                 else
1220                         xb_free_command(cm);
1221         }
1222
1223         sc->ring.rsp_cons = i;
1224
1225         if (i != sc->ring.req_prod_pvt) {
1226                 int more_to_do;
1227                 RING_FINAL_CHECK_FOR_RESPONSES(&sc->ring, more_to_do);
1228                 if (more_to_do)
1229                         goto again;
1230         } else {
1231                 sc->ring.sring->rsp_event = i + 1;
1232         }
1233
1234         xb_startio(sc);
1235
1236         mtx_unlock(&sc->xb_io_lock);
1237 }
1238
1239 static void
1240 blkif_free(struct xb_softc *sc, int suspend)
1241 {
1242         uint8_t *sring_page_ptr;
1243         int i;
1244
1245         /* Prevent new requests being issued until we fix things up. */
1246         mtx_lock(&sc->xb_io_lock);
1247         sc->connected = suspend ?
1248                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1249         mtx_unlock(&sc->xb_io_lock);
1250
1251         /* Free resources associated with old device channel. */
1252         if (sc->ring.sring != NULL) {
1253                 sring_page_ptr = (uint8_t *)sc->ring.sring;
1254                 for (i = 0; i < sc->ring_pages; i++) {
1255                         if (sc->ring_ref[i] != GRANT_INVALID_REF) {
1256                                 gnttab_end_foreign_access_ref(sc->ring_ref[i]);
1257                                 sc->ring_ref[i] = GRANT_INVALID_REF;
1258                         }
1259                         sring_page_ptr += PAGE_SIZE;
1260                 }
1261                 free(sc->ring.sring, M_XENBLOCKFRONT);
1262                 sc->ring.sring = NULL;
1263         }
1264
1265         if (sc->shadow) {
1266
1267                 for (i = 0; i < sc->max_requests; i++) {
1268                         struct xb_command *cm;
1269
1270                         cm = &sc->shadow[i];
1271                         if (cm->sg_refs != NULL) {
1272                                 free(cm->sg_refs, M_XENBLOCKFRONT);
1273                                 cm->sg_refs = NULL;
1274                         }
1275
1276                         bus_dmamap_destroy(sc->xb_io_dmat, cm->map);
1277                 }
1278                 free(sc->shadow, M_XENBLOCKFRONT);
1279                 sc->shadow = NULL;
1280         }
1281
1282         if (sc->irq) {
1283                 unbind_from_irqhandler(sc->irq);
1284                 sc->irq = 0;
1285         }
1286 }
1287
1288 static int
1289 blkif_completion(struct xb_command *s)
1290 {
1291 //printf("%s: Req %p(%d)\n", __func__, s, s->nseg);
1292         gnttab_end_foreign_access_references(s->nseg, s->sg_refs);
1293         return (BLKIF_SEGS_TO_BLOCKS(s->nseg));
1294 }
1295
1296 #if 0
1297 static void
1298 blkif_recover(struct xb_softc *sc)
1299 {
1300         /*
1301          * XXX The whole concept of not quiescing and completing all i/o
1302          * during suspend, and then hoping to recover and replay the
1303          * resulting abandoned I/O during resume, is laughable.  At best,
1304          * it invalidates the i/o ordering rules required by just about
1305          * every filesystem, and at worst it'll corrupt data.  The code
1306          * has been removed until further notice.
1307          */
1308 }
1309 #endif
1310
1311 /* ** Driver registration ** */
1312 static device_method_t blkfront_methods[] = {
1313         /* Device interface */
1314         DEVMETHOD(device_probe,         blkfront_probe),
1315         DEVMETHOD(device_attach,        blkfront_attach),
1316         DEVMETHOD(device_detach,        blkfront_detach),
1317         DEVMETHOD(device_shutdown,      bus_generic_shutdown),
1318         DEVMETHOD(device_suspend,       blkfront_suspend),
1319         DEVMETHOD(device_resume,        blkfront_resume),
1320
1321         /* Xenbus interface */
1322         DEVMETHOD(xenbus_otherend_changed, blkfront_backend_changed),
1323
1324         { 0, 0 }
1325 };
1326
1327 static driver_t blkfront_driver = {
1328         "xbd",
1329         blkfront_methods,
1330         sizeof(struct xb_softc),
1331 };
1332 devclass_t blkfront_devclass;
1333
1334 DRIVER_MODULE(xbd, xenbusb_front, blkfront_driver, blkfront_devclass, 0, 0);