drivers/block/xen-blkback/xenbus.c

   1 /*  Xenbus code for blkif backend
   2     Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
   3     Copyright (C) 2005 XenSource Ltd
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15 */
  16
  17 #include <stdarg.h>
  18 #include <linux/module.h>
  19 #include <linux/kthread.h>
  20 #include <xen/events.h>
  21 #include <xen/grant_table.h>
  22 #include "common.h"
  23
  24 struct backend_info {
  25         struct xenbus_device    *dev;
  26         struct xen_blkif        *blkif;
  27         struct xenbus_watch     backend_watch;
  28         unsigned                major;
  29         unsigned                minor;
  30         char                    *mode;
  31 };
  32
  33 static struct kmem_cache *xen_blkif_cachep;
  34 static void connect(struct backend_info *);
  35 static int connect_ring(struct backend_info *);
  36 static void backend_changed(struct xenbus_watch *, const char **,
  37                             unsigned int);
  38
  39 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
  40 {
  41         return be->dev;
  42 }
  43
  44 static int blkback_name(struct xen_blkif *blkif, char *buf)
  45 {
  46         char *devpath, *devname;
  47         struct xenbus_device *dev = blkif->be->dev;
  48
  49         devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
  50         if (IS_ERR(devpath))
  51                 return PTR_ERR(devpath);
  52
  53         devname = strstr(devpath, "/dev/");
  54         if (devname != NULL)
  55                 devname += strlen("/dev/");
  56         else
  57                 devname  = devpath;
  58
  59         snprintf(buf, TASK_COMM_LEN, "blkback.%d.%s", blkif->domid, devname);
  60         kfree(devpath);
  61
  62         return 0;
  63 }
  64
  65 static void xen_update_blkif_status(struct xen_blkif *blkif)
  66 {
  67         int err;
  68         char name[TASK_COMM_LEN];
  69
  70         /* Not ready to connect? */
  71         if (!blkif->irq || !blkif->vbd.bdev)
  72                 return;
  73
  74         /* Already connected? */
  75         if (blkif->be->dev->state == XenbusStateConnected)
  76                 return;
  77
  78         /* Attempt to connect: exit if we fail to. */
  79         connect(blkif->be);
  80         if (blkif->be->dev->state != XenbusStateConnected)
  81                 return;
  82
  83         err = blkback_name(blkif, name);
  84         if (err) {
  85                 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
  86                 return;
  87         }
  88
  89         err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
  90         if (err) {
  91                 xenbus_dev_error(blkif->be->dev, err, "block flush");
  92                 return;
  93         }
  94         invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
  95
  96         blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, name);
  97         if (IS_ERR(blkif->xenblkd)) {
  98                 err = PTR_ERR(blkif->xenblkd);
  99                 blkif->xenblkd = NULL;
 100                 xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
 101         }
 102 }
 103
 104 static struct xen_blkif *xen_blkif_alloc(domid_t domid)
 105 {
 106         struct xen_blkif *blkif;
 107
 108         blkif = kmem_cache_alloc(xen_blkif_cachep, GFP_KERNEL);
 109         if (!blkif)
 110                 return ERR_PTR(-ENOMEM);
 111
 112         memset(blkif, 0, sizeof(*blkif));
 113         blkif->domid = domid;
 114         spin_lock_init(&blkif->blk_ring_lock);
 115         atomic_set(&blkif->refcnt, 1);
 116         init_waitqueue_head(&blkif->wq);
 117         blkif->st_print = jiffies;
 118         init_waitqueue_head(&blkif->waiting_to_free);
 119
 120         return blkif;
 121 }
 122
 123 static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
 124                          unsigned int evtchn)
 125 {
 126         int err;
 127
 128         /* Already connected through? */
 129         if (blkif->irq)
 130                 return 0;
 131
 132         err = xenbus_map_ring_valloc(blkif->be->dev, shared_page, &blkif->blk_ring);
 133         if (err < 0)
 134                 return err;
 135
 136         switch (blkif->blk_protocol) {
 137         case BLKIF_PROTOCOL_NATIVE:
 138         {
 139                 struct blkif_sring *sring;
 140                 sring = (struct blkif_sring *)blkif->blk_ring;
 141                 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
 142                 break;
 143         }
 144         case BLKIF_PROTOCOL_X86_32:
 145         {
 146                 struct blkif_x86_32_sring *sring_x86_32;
 147                 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring;
 148                 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
 149                 break;
 150         }
 151         case BLKIF_PROTOCOL_X86_64:
 152         {
 153                 struct blkif_x86_64_sring *sring_x86_64;
 154                 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring;
 155                 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
 156                 break;
 157         }
 158         default:
 159                 BUG();
 160         }
 161
 162         err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn,
 163                                                     xen_blkif_be_int, 0,
 164                                                     "blkif-backend", blkif);
 165         if (err < 0) {
 166                 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
 167                 blkif->blk_rings.common.sring = NULL;
 168                 return err;
 169         }
 170         blkif->irq = err;
 171
 172         return 0;
 173 }
 174
 175 static void xen_blkif_disconnect(struct xen_blkif *blkif)
 176 {
 177         if (blkif->xenblkd) {
 178                 kthread_stop(blkif->xenblkd);
 179                 blkif->xenblkd = NULL;
 180         }
 181
 182         atomic_dec(&blkif->refcnt);
 183         wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
 184         atomic_inc(&blkif->refcnt);
 185
 186         if (blkif->irq) {
 187                 unbind_from_irqhandler(blkif->irq, blkif);
 188                 blkif->irq = 0;
 189         }
 190
 191         if (blkif->blk_rings.common.sring) {
 192                 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
 193                 blkif->blk_rings.common.sring = NULL;
 194         }
 195 }
 196
 197 void xen_blkif_free(struct xen_blkif *blkif)
 198 {
 199         if (!atomic_dec_and_test(&blkif->refcnt))
 200                 BUG();
 201         kmem_cache_free(xen_blkif_cachep, blkif);
 202 }
 203
 204 int __init xen_blkif_interface_init(void)
 205 {
 206         xen_blkif_cachep = kmem_cache_create("blkif_cache",
 207                                              sizeof(struct xen_blkif),
 208                                              0, 0, NULL);
 209         if (!xen_blkif_cachep)
 210                 return -ENOMEM;
 211
 212         return 0;
 213 }
 214
 215 /*
 216  *  sysfs interface for VBD I/O requests
 217  */
 218
 219 #define VBD_SHOW(name, format, args...)                                 \
 220         static ssize_t show_##name(struct device *_dev,                 \
 221                                    struct device_attribute *attr,       \
 222                                    char *buf)                           \
 223         {                                                               \
 224                 struct xenbus_device *dev = to_xenbus_device(_dev);     \
 225                 struct backend_info *be = dev_get_drvdata(&dev->dev);   \
 226                                                                         \
 227                 return sprintf(buf, format, ##args);                    \
 228         }                                                               \
 229         static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
 230
 231 VBD_SHOW(oo_req,  "%d\n", be->blkif->st_oo_req);
 232 VBD_SHOW(rd_req,  "%d\n", be->blkif->st_rd_req);
 233 VBD_SHOW(wr_req,  "%d\n", be->blkif->st_wr_req);
 234 VBD_SHOW(f_req,  "%d\n", be->blkif->st_f_req);
 235 VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect);
 236 VBD_SHOW(wr_sect, "%d\n", be->blkif->st_wr_sect);
 237
 238 static struct attribute *xen_vbdstat_attrs[] = {
 239         &dev_attr_oo_req.attr,
 240         &dev_attr_rd_req.attr,
 241         &dev_attr_wr_req.attr,
 242         &dev_attr_f_req.attr,
 243         &dev_attr_rd_sect.attr,
 244         &dev_attr_wr_sect.attr,
 245         NULL
 246 };
 247
 248 static struct attribute_group xen_vbdstat_group = {
 249         .name = "statistics",
 250         .attrs = xen_vbdstat_attrs,
 251 };
 252
 253 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
 254 VBD_SHOW(mode, "%s\n", be->mode);
 255
 256 int xenvbd_sysfs_addif(struct xenbus_device *dev)
 257 {
 258         int error;
 259
 260         error = device_create_file(&dev->dev, &dev_attr_physical_device);
 261         if (error)
 262                 goto fail1;
 263
 264         error = device_create_file(&dev->dev, &dev_attr_mode);
 265         if (error)
 266                 goto fail2;
 267
 268         error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
 269         if (error)
 270                 goto fail3;
 271
 272         return 0;
 273
 274 fail3:  sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
 275 fail2:  device_remove_file(&dev->dev, &dev_attr_mode);
 276 fail1:  device_remove_file(&dev->dev, &dev_attr_physical_device);
 277         return error;
 278 }
 279
 280 void xenvbd_sysfs_delif(struct xenbus_device *dev)
 281 {
 282         sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
 283         device_remove_file(&dev->dev, &dev_attr_mode);
 284         device_remove_file(&dev->dev, &dev_attr_physical_device);
 285 }
 286
 287
 288 static void xen_vbd_free(struct xen_vbd *vbd)
 289 {
 290         if (vbd->bdev)
 291                 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
 292         vbd->bdev = NULL;
 293 }
 294
 295 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
 296                           unsigned major, unsigned minor, int readonly,
 297                           int cdrom)
 298 {
 299         struct xen_vbd *vbd;
 300         struct block_device *bdev;
 301         struct request_queue *q;
 302
 303         vbd = &blkif->vbd;
 304         vbd->handle   = handle;
 305         vbd->readonly = readonly;
 306         vbd->type     = 0;
 307
 308         vbd->pdevice  = MKDEV(major, minor);
 309
 310         bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
 311                                  FMODE_READ : FMODE_WRITE, NULL);
 312
 313         if (IS_ERR(bdev)) {
 314                 DPRINTK("xen_vbd_create: device %08x could not be opened.\n",
 315                         vbd->pdevice);
 316                 return -ENOENT;
 317         }
 318
 319         vbd->bdev = bdev;
 320         if (vbd->bdev->bd_disk == NULL) {
 321                 DPRINTK("xen_vbd_create: device %08x doesn't exist.\n",
 322                         vbd->pdevice);
 323                 xen_vbd_free(vbd);
 324                 return -ENOENT;
 325         }
 326         vbd->size = vbd_sz(vbd);
 327
 328         if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
 329                 vbd->type |= VDISK_CDROM;
 330         if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
 331                 vbd->type |= VDISK_REMOVABLE;
 332
 333         q = bdev_get_queue(bdev);
 334         if (q && q->flush_flags)
 335                 vbd->flush_support = true;
 336
 337         DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
 338                 handle, blkif->domid);
 339         return 0;
 340 }
 341 static int xen_blkbk_remove(struct xenbus_device *dev)
 342 {
 343         struct backend_info *be = dev_get_drvdata(&dev->dev);
 344
 345         DPRINTK("");
 346
 347         if (be->major || be->minor)
 348                 xenvbd_sysfs_delif(dev);
 349
 350         if (be->backend_watch.node) {
 351                 unregister_xenbus_watch(&be->backend_watch);
 352                 kfree(be->backend_watch.node);
 353                 be->backend_watch.node = NULL;
 354         }
 355
 356         if (be->blkif) {
 357                 xen_blkif_disconnect(be->blkif);
 358                 xen_vbd_free(&be->blkif->vbd);
 359                 xen_blkif_free(be->blkif);
 360                 be->blkif = NULL;
 361         }
 362
 363         kfree(be);
 364         dev_set_drvdata(&dev->dev, NULL);
 365         return 0;
 366 }
 367
 368 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 369                               struct backend_info *be, int state)
 370 {
 371         struct xenbus_device *dev = be->dev;
 372         int err;
 373
 374         err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
 375                             "%d", state);
 376         if (err)
 377                 xenbus_dev_fatal(dev, err, "writing feature-flush-cache");
 378
 379         return err;
 380 }
 381
 382 /*
 383  * Entry point to this code when a new device is created.  Allocate the basic
 384  * structures, and watch the store waiting for the hotplug scripts to tell us
 385  * the device's physical major and minor numbers.  Switch to InitWait.
 386  */
 387 static int xen_blkbk_probe(struct xenbus_device *dev,
 388                            const struct xenbus_device_id *id)
 389 {
 390         int err;
 391         struct backend_info *be = kzalloc(sizeof(struct backend_info),
 392                                           GFP_KERNEL);
 393         if (!be) {
 394                 xenbus_dev_fatal(dev, -ENOMEM,
 395                                  "allocating backend structure");
 396                 return -ENOMEM;
 397         }
 398         be->dev = dev;
 399         dev_set_drvdata(&dev->dev, be);
 400
 401         be->blkif = xen_blkif_alloc(dev->otherend_id);
 402         if (IS_ERR(be->blkif)) {
 403                 err = PTR_ERR(be->blkif);
 404                 be->blkif = NULL;
 405                 xenbus_dev_fatal(dev, err, "creating block interface");
 406                 goto fail;
 407         }
 408
 409         /* setup back pointer */
 410         be->blkif->be = be;
 411
 412         err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
 413                                    "%s/%s", dev->nodename, "physical-device");
 414         if (err)
 415                 goto fail;
 416
 417         err = xenbus_switch_state(dev, XenbusStateInitWait);
 418         if (err)
 419                 goto fail;
 420
 421         return 0;
 422
 423 fail:
 424         DPRINTK("failed");
 425         xen_blkbk_remove(dev);
 426         return err;
 427 }
 428
 429
 430 /*
 431  * Callback received when the hotplug scripts have placed the physical-device
 432  * node.  Read it and the mode node, and create a vbd.  If the frontend is
 433  * ready, connect.
 434  */
 435 static void backend_changed(struct xenbus_watch *watch,
 436                             const char **vec, unsigned int len)
 437 {
 438         int err;
 439         unsigned major;
 440         unsigned minor;
 441         struct backend_info *be
 442                 = container_of(watch, struct backend_info, backend_watch);
 443         struct xenbus_device *dev = be->dev;
 444         int cdrom = 0;
 445         char *device_type;
 446
 447         DPRINTK("");
 448
 449         err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
 450                            &major, &minor);
 451         if (XENBUS_EXIST_ERR(err)) {
 452                 /*
 453                  * Since this watch will fire once immediately after it is
 454                  * registered, we expect this.  Ignore it, and wait for the
 455                  * hotplug scripts.
 456                  */
 457                 return;
 458         }
 459         if (err != 2) {
 460                 xenbus_dev_fatal(dev, err, "reading physical-device");
 461                 return;
 462         }
 463
 464         if ((be->major || be->minor) &&
 465             ((be->major != major) || (be->minor != minor))) {
 466                 pr_warn(DRV_PFX "changing physical device (from %x:%x to %x:%x) not supported.\n",
 467                         be->major, be->minor, major, minor);
 468                 return;
 469         }
 470
 471         be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
 472         if (IS_ERR(be->mode)) {
 473                 err = PTR_ERR(be->mode);
 474                 be->mode = NULL;
 475                 xenbus_dev_fatal(dev, err, "reading mode");
 476                 return;
 477         }
 478
 479         device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
 480         if (!IS_ERR(device_type)) {
 481                 cdrom = strcmp(device_type, "cdrom") == 0;
 482                 kfree(device_type);
 483         }
 484
 485         if (be->major == 0 && be->minor == 0) {
 486                 /* Front end dir is a number, which is used as the handle. */
 487
 488                 char *p = strrchr(dev->otherend, '/') + 1;
 489                 long handle;
 490                 err = strict_strtoul(p, 0, &handle);
 491                 if (err)
 492                         return;
 493
 494                 be->major = major;
 495                 be->minor = minor;
 496
 497                 err = xen_vbd_create(be->blkif, handle, major, minor,
 498                                  (NULL == strchr(be->mode, 'w')), cdrom);
 499                 if (err) {
 500                         be->major = 0;
 501                         be->minor = 0;
 502                         xenbus_dev_fatal(dev, err, "creating vbd structure");
 503                         return;
 504                 }
 505
 506                 err = xenvbd_sysfs_addif(dev);
 507                 if (err) {
 508                         xen_vbd_free(&be->blkif->vbd);
 509                         be->major = 0;
 510                         be->minor = 0;
 511                         xenbus_dev_fatal(dev, err, "creating sysfs entries");
 512                         return;
 513                 }
 514
 515                 /* We're potentially connected now */
 516                 xen_update_blkif_status(be->blkif);
 517         }
 518 }
 519
 520
 521 /*
 522  * Callback received when the frontend's state changes.
 523  */
 524 static void frontend_changed(struct xenbus_device *dev,
 525                              enum xenbus_state frontend_state)
 526 {
 527         struct backend_info *be = dev_get_drvdata(&dev->dev);
 528         int err;
 529
 530         DPRINTK("%s", xenbus_strstate(frontend_state));
 531
 532         switch (frontend_state) {
 533         case XenbusStateInitialising:
 534                 if (dev->state == XenbusStateClosed) {
 535                         pr_info(DRV_PFX "%s: prepare for reconnect\n",
 536                                 dev->nodename);
 537                         xenbus_switch_state(dev, XenbusStateInitWait);
 538                 }
 539                 break;
 540
 541         case XenbusStateInitialised:
 542         case XenbusStateConnected:
 543                 /*
 544                  * Ensure we connect even when two watches fire in
 545                  * close successsion and we miss the intermediate value
 546                  * of frontend_state.
 547                  */
 548                 if (dev->state == XenbusStateConnected)
 549                         break;
 550
 551                 /*
 552                  * Enforce precondition before potential leak point.
 553                  * xen_blkif_disconnect() is idempotent.
 554                  */
 555                 xen_blkif_disconnect(be->blkif);
 556
 557                 err = connect_ring(be);
 558                 if (err)
 559                         break;
 560                 xen_update_blkif_status(be->blkif);
 561                 break;
 562
 563         case XenbusStateClosing:
 564                 xenbus_switch_state(dev, XenbusStateClosing);
 565                 break;
 566
 567         case XenbusStateClosed:
 568                 xen_blkif_disconnect(be->blkif);
 569                 xenbus_switch_state(dev, XenbusStateClosed);
 570                 if (xenbus_dev_is_online(dev))
 571                         break;
 572                 /* fall through if not online */
 573         case XenbusStateUnknown:
 574                 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
 575                 device_unregister(&dev->dev);
 576                 break;
 577
 578         default:
 579                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 580                                  frontend_state);
 581                 break;
 582         }
 583 }
 584
 585
 586 /* ** Connection ** */
 587
 588
 589 /*
 590  * Write the physical details regarding the block device to the store, and
 591  * switch to Connected state.
 592  */
 593 static void connect(struct backend_info *be)
 594 {
 595         struct xenbus_transaction xbt;
 596         int err;
 597         struct xenbus_device *dev = be->dev;
 598
 599         DPRINTK("%s", dev->otherend);
 600
 601         /* Supply the information about the device the frontend needs */
 602 again:
 603         err = xenbus_transaction_start(&xbt);
 604         if (err) {
 605                 xenbus_dev_fatal(dev, err, "starting transaction");
 606                 return;
 607         }
 608
 609         err = xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
 610         if (err)
 611                 goto abort;
 612
 613         err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
 614                             (unsigned long long)vbd_sz(&be->blkif->vbd));
 615         if (err) {
 616                 xenbus_dev_fatal(dev, err, "writing %s/sectors",
 617                                  dev->nodename);
 618                 goto abort;
 619         }
 620
 621         /* FIXME: use a typename instead */
 622         err = xenbus_printf(xbt, dev->nodename, "info", "%u",
 623                             be->blkif->vbd.type |
 624                             (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
 625         if (err) {
 626                 xenbus_dev_fatal(dev, err, "writing %s/info",
 627                                  dev->nodename);
 628                 goto abort;
 629         }
 630         err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
 631                             (unsigned long)
 632                             bdev_logical_block_size(be->blkif->vbd.bdev));
 633         if (err) {
 634                 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
 635                                  dev->nodename);
 636                 goto abort;
 637         }
 638
 639         err = xenbus_transaction_end(xbt, 0);
 640         if (err == -EAGAIN)
 641                 goto again;
 642         if (err)
 643                 xenbus_dev_fatal(dev, err, "ending transaction");
 644
 645         err = xenbus_switch_state(dev, XenbusStateConnected);
 646         if (err)
 647                 xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
 648                                  dev->nodename);
 649
 650         return;
 651  abort:
 652         xenbus_transaction_end(xbt, 1);
 653 }
 654
 655
 656 static int connect_ring(struct backend_info *be)
 657 {
 658         struct xenbus_device *dev = be->dev;
 659         unsigned long ring_ref;
 660         unsigned int evtchn;
 661         char protocol[64] = "";
 662         int err;
 663
 664         DPRINTK("%s", dev->otherend);
 665
 666         err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu",
 667                             &ring_ref, "event-channel", "%u", &evtchn, NULL);
 668         if (err) {
 669                 xenbus_dev_fatal(dev, err,
 670                                  "reading %s/ring-ref and event-channel",
 671                                  dev->otherend);
 672                 return err;
 673         }
 674
 675         be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
 676         err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
 677                             "%63s", protocol, NULL);
 678         if (err)
 679                 strcpy(protocol, "unspecified, assuming native");
 680         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
 681                 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
 682         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
 683                 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
 684         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
 685                 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
 686         else {
 687                 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
 688                 return -1;
 689         }
 690         pr_info(DRV_PFX "ring-ref %ld, event-channel %d, protocol %d (%s)\n",
 691                 ring_ref, evtchn, be->blkif->blk_protocol, protocol);
 692
 693         /* Map the shared frame, irq etc. */
 694         err = xen_blkif_map(be->blkif, ring_ref, evtchn);
 695         if (err) {
 696                 xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u",
 697                                  ring_ref, evtchn);
 698                 return err;
 699         }
 700
 701         return 0;
 702 }
 703
 704
 705 /* ** Driver Registration ** */
 706
 707
 708 static const struct xenbus_device_id xen_blkbk_ids[] = {
 709         { "vbd" },
 710         { "" }
 711 };
 712
 713
 714 static struct xenbus_driver xen_blkbk = {
 715         .name = "vbd",
 716         .owner = THIS_MODULE,
 717         .ids = xen_blkbk_ids,
 718         .probe = xen_blkbk_probe,
 719         .remove = xen_blkbk_remove,
 720         .otherend_changed = frontend_changed
 721 };
 722
 723
 724 int xen_blkif_xenbus_init(void)
 725 {
 726         return xenbus_register_backend(&xen_blkbk);
 727 }