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_zalloc(xen_blkif_cachep, GFP_KERNEL);
 109         if (!blkif)
 110                 return ERR_PTR(-ENOMEM);
 111
 112         blkif->domid = domid;
 113         spin_lock_init(&blkif->blk_ring_lock);
 114         atomic_set(&blkif->refcnt, 1);
 115         init_waitqueue_head(&blkif->wq);
 116         init_completion(&blkif->drain_complete);
 117         atomic_set(&blkif->drain, 0);
 118         blkif->st_print = jiffies;
 119         init_waitqueue_head(&blkif->waiting_to_free);
 120
 121         return blkif;
 122 }
 123
 124 static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page,
 125                          unsigned int evtchn)
 126 {
 127         int err;
 128
 129         /* Already connected through? */
 130         if (blkif->irq)
 131                 return 0;
 132
 133         err = xenbus_map_ring_valloc(blkif->be->dev, shared_page, &blkif->blk_ring);
 134         if (err < 0)
 135                 return err;
 136
 137         switch (blkif->blk_protocol) {
 138         case BLKIF_PROTOCOL_NATIVE:
 139         {
 140                 struct blkif_sring *sring;
 141                 sring = (struct blkif_sring *)blkif->blk_ring;
 142                 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE);
 143                 break;
 144         }
 145         case BLKIF_PROTOCOL_X86_32:
 146         {
 147                 struct blkif_x86_32_sring *sring_x86_32;
 148                 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring;
 149                 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE);
 150                 break;
 151         }
 152         case BLKIF_PROTOCOL_X86_64:
 153         {
 154                 struct blkif_x86_64_sring *sring_x86_64;
 155                 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring;
 156                 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE);
 157                 break;
 158         }
 159         default:
 160                 BUG();
 161         }
 162
 163         err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn,
 164                                                     xen_blkif_be_int, 0,
 165                                                     "blkif-backend", blkif);
 166         if (err < 0) {
 167                 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
 168                 blkif->blk_rings.common.sring = NULL;
 169                 return err;
 170         }
 171         blkif->irq = err;
 172
 173         return 0;
 174 }
 175
 176 static void xen_blkif_disconnect(struct xen_blkif *blkif)
 177 {
 178         if (blkif->xenblkd) {
 179                 kthread_stop(blkif->xenblkd);
 180                 blkif->xenblkd = NULL;
 181         }
 182
 183         atomic_dec(&blkif->refcnt);
 184         wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0);
 185         atomic_inc(&blkif->refcnt);
 186
 187         if (blkif->irq) {
 188                 unbind_from_irqhandler(blkif->irq, blkif);
 189                 blkif->irq = 0;
 190         }
 191
 192         if (blkif->blk_rings.common.sring) {
 193                 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
 194                 blkif->blk_rings.common.sring = NULL;
 195         }
 196 }
 197
 198 static void xen_blkif_free(struct xen_blkif *blkif)
 199 {
 200         if (!atomic_dec_and_test(&blkif->refcnt))
 201                 BUG();
 202         kmem_cache_free(xen_blkif_cachep, blkif);
 203 }
 204
 205 int __init xen_blkif_interface_init(void)
 206 {
 207         xen_blkif_cachep = kmem_cache_create("blkif_cache",
 208                                              sizeof(struct xen_blkif),
 209                                              0, 0, NULL);
 210         if (!xen_blkif_cachep)
 211                 return -ENOMEM;
 212
 213         return 0;
 214 }
 215
 216 /*
 217  *  sysfs interface for VBD I/O requests
 218  */
 219
 220 #define VBD_SHOW(name, format, args...)                                 \
 221         static ssize_t show_##name(struct device *_dev,                 \
 222                                    struct device_attribute *attr,       \
 223                                    char *buf)                           \
 224         {                                                               \
 225                 struct xenbus_device *dev = to_xenbus_device(_dev);     \
 226                 struct backend_info *be = dev_get_drvdata(&dev->dev);   \
 227                                                                         \
 228                 return sprintf(buf, format, ##args);                    \
 229         }                                                               \
 230         static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
 231
 232 VBD_SHOW(oo_req,  "%d\n", be->blkif->st_oo_req);
 233 VBD_SHOW(rd_req,  "%d\n", be->blkif->st_rd_req);
 234 VBD_SHOW(wr_req,  "%d\n", be->blkif->st_wr_req);
 235 VBD_SHOW(f_req,  "%d\n", be->blkif->st_f_req);
 236 VBD_SHOW(ds_req,  "%d\n", be->blkif->st_ds_req);
 237 VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect);
 238 VBD_SHOW(wr_sect, "%d\n", be->blkif->st_wr_sect);
 239
 240 static struct attribute *xen_vbdstat_attrs[] = {
 241         &dev_attr_oo_req.attr,
 242         &dev_attr_rd_req.attr,
 243         &dev_attr_wr_req.attr,
 244         &dev_attr_f_req.attr,
 245         &dev_attr_ds_req.attr,
 246         &dev_attr_rd_sect.attr,
 247         &dev_attr_wr_sect.attr,
 248         NULL
 249 };
 250
 251 static struct attribute_group xen_vbdstat_group = {
 252         .name = "statistics",
 253         .attrs = xen_vbdstat_attrs,
 254 };
 255
 256 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
 257 VBD_SHOW(mode, "%s\n", be->mode);
 258
 259 static int xenvbd_sysfs_addif(struct xenbus_device *dev)
 260 {
 261         int error;
 262
 263         error = device_create_file(&dev->dev, &dev_attr_physical_device);
 264         if (error)
 265                 goto fail1;
 266
 267         error = device_create_file(&dev->dev, &dev_attr_mode);
 268         if (error)
 269                 goto fail2;
 270
 271         error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
 272         if (error)
 273                 goto fail3;
 274
 275         return 0;
 276
 277 fail3:  sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
 278 fail2:  device_remove_file(&dev->dev, &dev_attr_mode);
 279 fail1:  device_remove_file(&dev->dev, &dev_attr_physical_device);
 280         return error;
 281 }
 282
 283 static void xenvbd_sysfs_delif(struct xenbus_device *dev)
 284 {
 285         sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
 286         device_remove_file(&dev->dev, &dev_attr_mode);
 287         device_remove_file(&dev->dev, &dev_attr_physical_device);
 288 }
 289
 290
 291 static void xen_vbd_free(struct xen_vbd *vbd)
 292 {
 293         if (vbd->bdev)
 294                 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
 295         vbd->bdev = NULL;
 296 }
 297
 298 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
 299                           unsigned major, unsigned minor, int readonly,
 300                           int cdrom)
 301 {
 302         struct xen_vbd *vbd;
 303         struct block_device *bdev;
 304         struct request_queue *q;
 305
 306         vbd = &blkif->vbd;
 307         vbd->handle   = handle;
 308         vbd->readonly = readonly;
 309         vbd->type     = 0;
 310
 311         vbd->pdevice  = MKDEV(major, minor);
 312
 313         bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
 314                                  FMODE_READ : FMODE_WRITE, NULL);
 315
 316         if (IS_ERR(bdev)) {
 317                 DPRINTK("xen_vbd_create: device %08x could not be opened.\n",
 318                         vbd->pdevice);
 319                 return -ENOENT;
 320         }
 321
 322         vbd->bdev = bdev;
 323         if (vbd->bdev->bd_disk == NULL) {
 324                 DPRINTK("xen_vbd_create: device %08x doesn't exist.\n",
 325                         vbd->pdevice);
 326                 xen_vbd_free(vbd);
 327                 return -ENOENT;
 328         }
 329         vbd->size = vbd_sz(vbd);
 330
 331         if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
 332                 vbd->type |= VDISK_CDROM;
 333         if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
 334                 vbd->type |= VDISK_REMOVABLE;
 335
 336         q = bdev_get_queue(bdev);
 337         if (q && q->flush_flags)
 338                 vbd->flush_support = true;
 339
 340         if (q && blk_queue_secdiscard(q))
 341                 vbd->discard_secure = true;
 342
 343         DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
 344                 handle, blkif->domid);
 345         return 0;
 346 }
 347 static int xen_blkbk_remove(struct xenbus_device *dev)
 348 {
 349         struct backend_info *be = dev_get_drvdata(&dev->dev);
 350
 351         DPRINTK("");
 352
 353         if (be->major || be->minor)
 354                 xenvbd_sysfs_delif(dev);
 355
 356         if (be->backend_watch.node) {
 357                 unregister_xenbus_watch(&be->backend_watch);
 358                 kfree(be->backend_watch.node);
 359                 be->backend_watch.node = NULL;
 360         }
 361
 362         if (be->blkif) {
 363                 xen_blkif_disconnect(be->blkif);
 364                 xen_vbd_free(&be->blkif->vbd);
 365                 xen_blkif_free(be->blkif);
 366                 be->blkif = NULL;
 367         }
 368
 369         kfree(be);
 370         dev_set_drvdata(&dev->dev, NULL);
 371         return 0;
 372 }
 373
 374 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 375                               struct backend_info *be, int state)
 376 {
 377         struct xenbus_device *dev = be->dev;
 378         int err;
 379
 380         err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
 381                             "%d", state);
 382         if (err)
 383                 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err);
 384
 385         return err;
 386 }
 387
 388 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
 389 {
 390         struct xenbus_device *dev = be->dev;
 391         struct xen_blkif *blkif = be->blkif;
 392         int err;
 393         int state = 0;
 394         struct block_device *bdev = be->blkif->vbd.bdev;
 395         struct request_queue *q = bdev_get_queue(bdev);
 396
 397         if (blk_queue_discard(q)) {
 398                 err = xenbus_printf(xbt, dev->nodename,
 399                         "discard-granularity", "%u",
 400                         q->limits.discard_granularity);
 401                 if (err) {
 402                         dev_warn(&dev->dev, "writing discard-granularity (%d)", err);
 403                         return;
 404                 }
 405                 err = xenbus_printf(xbt, dev->nodename,
 406                         "discard-alignment", "%u",
 407                         q->limits.discard_alignment);
 408                 if (err) {
 409                         dev_warn(&dev->dev, "writing discard-alignment (%d)", err);
 410                         return;
 411                 }
 412                 state = 1;
 413                 /* Optional. */
 414                 err = xenbus_printf(xbt, dev->nodename,
 415                                     "discard-secure", "%d",
 416                                     blkif->vbd.discard_secure);
 417                 if (err) {
 418                         dev_warn(&dev->dev, "writing discard-secure (%d)", err);
 419                         return;
 420                 }
 421         }
 422         err = xenbus_printf(xbt, dev->nodename, "feature-discard",
 423                             "%d", state);
 424         if (err)
 425                 dev_warn(&dev->dev, "writing feature-discard (%d)", err);
 426 }
 427 int xen_blkbk_barrier(struct xenbus_transaction xbt,
 428                       struct backend_info *be, int state)
 429 {
 430         struct xenbus_device *dev = be->dev;
 431         int err;
 432
 433         err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
 434                             "%d", state);
 435         if (err)
 436                 dev_warn(&dev->dev, "writing feature-barrier (%d)", err);
 437
 438         return err;
 439 }
 440
 441 /*
 442  * Entry point to this code when a new device is created.  Allocate the basic
 443  * structures, and watch the store waiting for the hotplug scripts to tell us
 444  * the device's physical major and minor numbers.  Switch to InitWait.
 445  */
 446 static int xen_blkbk_probe(struct xenbus_device *dev,
 447                            const struct xenbus_device_id *id)
 448 {
 449         int err;
 450         struct backend_info *be = kzalloc(sizeof(struct backend_info),
 451                                           GFP_KERNEL);
 452         if (!be) {
 453                 xenbus_dev_fatal(dev, -ENOMEM,
 454                                  "allocating backend structure");
 455                 return -ENOMEM;
 456         }
 457         be->dev = dev;
 458         dev_set_drvdata(&dev->dev, be);
 459
 460         be->blkif = xen_blkif_alloc(dev->otherend_id);
 461         if (IS_ERR(be->blkif)) {
 462                 err = PTR_ERR(be->blkif);
 463                 be->blkif = NULL;
 464                 xenbus_dev_fatal(dev, err, "creating block interface");
 465                 goto fail;
 466         }
 467
 468         /* setup back pointer */
 469         be->blkif->be = be;
 470
 471         err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
 472                                    "%s/%s", dev->nodename, "physical-device");
 473         if (err)
 474                 goto fail;
 475
 476         err = xenbus_switch_state(dev, XenbusStateInitWait);
 477         if (err)
 478                 goto fail;
 479
 480         return 0;
 481
 482 fail:
 483         DPRINTK("failed");
 484         xen_blkbk_remove(dev);
 485         return err;
 486 }
 487
 488
 489 /*
 490  * Callback received when the hotplug scripts have placed the physical-device
 491  * node.  Read it and the mode node, and create a vbd.  If the frontend is
 492  * ready, connect.
 493  */
 494 static void backend_changed(struct xenbus_watch *watch,
 495                             const char **vec, unsigned int len)
 496 {
 497         int err;
 498         unsigned major;
 499         unsigned minor;
 500         struct backend_info *be
 501                 = container_of(watch, struct backend_info, backend_watch);
 502         struct xenbus_device *dev = be->dev;
 503         int cdrom = 0;
 504         char *device_type;
 505
 506         DPRINTK("");
 507
 508         err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
 509                            &major, &minor);
 510         if (XENBUS_EXIST_ERR(err)) {
 511                 /*
 512                  * Since this watch will fire once immediately after it is
 513                  * registered, we expect this.  Ignore it, and wait for the
 514                  * hotplug scripts.
 515                  */
 516                 return;
 517         }
 518         if (err != 2) {
 519                 xenbus_dev_fatal(dev, err, "reading physical-device");
 520                 return;
 521         }
 522
 523         if ((be->major || be->minor) &&
 524             ((be->major != major) || (be->minor != minor))) {
 525                 pr_warn(DRV_PFX "changing physical device (from %x:%x to %x:%x) not supported.\n",
 526                         be->major, be->minor, major, minor);
 527                 return;
 528         }
 529
 530         be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
 531         if (IS_ERR(be->mode)) {
 532                 err = PTR_ERR(be->mode);
 533                 be->mode = NULL;
 534                 xenbus_dev_fatal(dev, err, "reading mode");
 535                 return;
 536         }
 537
 538         device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
 539         if (!IS_ERR(device_type)) {
 540                 cdrom = strcmp(device_type, "cdrom") == 0;
 541                 kfree(device_type);
 542         }
 543
 544         if (be->major == 0 && be->minor == 0) {
 545                 /* Front end dir is a number, which is used as the handle. */
 546
 547                 char *p = strrchr(dev->otherend, '/') + 1;
 548                 long handle;
 549                 err = strict_strtoul(p, 0, &handle);
 550                 if (err)
 551                         return;
 552
 553                 be->major = major;
 554                 be->minor = minor;
 555
 556                 err = xen_vbd_create(be->blkif, handle, major, minor,
 557                                  (NULL == strchr(be->mode, 'w')), cdrom);
 558                 if (err) {
 559                         be->major = 0;
 560                         be->minor = 0;
 561                         xenbus_dev_fatal(dev, err, "creating vbd structure");
 562                         return;
 563                 }
 564
 565                 err = xenvbd_sysfs_addif(dev);
 566                 if (err) {
 567                         xen_vbd_free(&be->blkif->vbd);
 568                         be->major = 0;
 569                         be->minor = 0;
 570                         xenbus_dev_fatal(dev, err, "creating sysfs entries");
 571                         return;
 572                 }
 573
 574                 /* We're potentially connected now */
 575                 xen_update_blkif_status(be->blkif);
 576         }
 577 }
 578
 579
 580 /*
 581  * Callback received when the frontend's state changes.
 582  */
 583 static void frontend_changed(struct xenbus_device *dev,
 584                              enum xenbus_state frontend_state)
 585 {
 586         struct backend_info *be = dev_get_drvdata(&dev->dev);
 587         int err;
 588
 589         DPRINTK("%s", xenbus_strstate(frontend_state));
 590
 591         switch (frontend_state) {
 592         case XenbusStateInitialising:
 593                 if (dev->state == XenbusStateClosed) {
 594                         pr_info(DRV_PFX "%s: prepare for reconnect\n",
 595                                 dev->nodename);
 596                         xenbus_switch_state(dev, XenbusStateInitWait);
 597                 }
 598                 break;
 599
 600         case XenbusStateInitialised:
 601         case XenbusStateConnected:
 602                 /*
 603                  * Ensure we connect even when two watches fire in
 604                  * close succession and we miss the intermediate value
 605                  * of frontend_state.
 606                  */
 607                 if (dev->state == XenbusStateConnected)
 608                         break;
 609
 610                 /*
 611                  * Enforce precondition before potential leak point.
 612                  * xen_blkif_disconnect() is idempotent.
 613                  */
 614                 xen_blkif_disconnect(be->blkif);
 615
 616                 err = connect_ring(be);
 617                 if (err)
 618                         break;
 619                 xen_update_blkif_status(be->blkif);
 620                 break;
 621
 622         case XenbusStateClosing:
 623                 xenbus_switch_state(dev, XenbusStateClosing);
 624                 break;
 625
 626         case XenbusStateClosed:
 627                 xen_blkif_disconnect(be->blkif);
 628                 xenbus_switch_state(dev, XenbusStateClosed);
 629                 if (xenbus_dev_is_online(dev))
 630                         break;
 631                 /* fall through if not online */
 632         case XenbusStateUnknown:
 633                 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
 634                 device_unregister(&dev->dev);
 635                 break;
 636
 637         default:
 638                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 639                                  frontend_state);
 640                 break;
 641         }
 642 }
 643
 644
 645 /* ** Connection ** */
 646
 647
 648 /*
 649  * Write the physical details regarding the block device to the store, and
 650  * switch to Connected state.
 651  */
 652 static void connect(struct backend_info *be)
 653 {
 654         struct xenbus_transaction xbt;
 655         int err;
 656         struct xenbus_device *dev = be->dev;
 657
 658         DPRINTK("%s", dev->otherend);
 659
 660         /* Supply the information about the device the frontend needs */
 661 again:
 662         err = xenbus_transaction_start(&xbt);
 663         if (err) {
 664                 xenbus_dev_fatal(dev, err, "starting transaction");
 665                 return;
 666         }
 667
 668         /* If we can't advertise it is OK. */
 669         xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
 670
 671         xen_blkbk_discard(xbt, be);
 672
 673         xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
 674
 675         err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
 676                             (unsigned long long)vbd_sz(&be->blkif->vbd));
 677         if (err) {
 678                 xenbus_dev_fatal(dev, err, "writing %s/sectors",
 679                                  dev->nodename);
 680                 goto abort;
 681         }
 682
 683         /* FIXME: use a typename instead */
 684         err = xenbus_printf(xbt, dev->nodename, "info", "%u",
 685                             be->blkif->vbd.type |
 686                             (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
 687         if (err) {
 688                 xenbus_dev_fatal(dev, err, "writing %s/info",
 689                                  dev->nodename);
 690                 goto abort;
 691         }
 692         err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
 693                             (unsigned long)
 694                             bdev_logical_block_size(be->blkif->vbd.bdev));
 695         if (err) {
 696                 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
 697                                  dev->nodename);
 698                 goto abort;
 699         }
 700
 701         err = xenbus_transaction_end(xbt, 0);
 702         if (err == -EAGAIN)
 703                 goto again;
 704         if (err)
 705                 xenbus_dev_fatal(dev, err, "ending transaction");
 706
 707         err = xenbus_switch_state(dev, XenbusStateConnected);
 708         if (err)
 709                 xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
 710                                  dev->nodename);
 711
 712         return;
 713  abort:
 714         xenbus_transaction_end(xbt, 1);
 715 }
 716
 717
 718 static int connect_ring(struct backend_info *be)
 719 {
 720         struct xenbus_device *dev = be->dev;
 721         unsigned long ring_ref;
 722         unsigned int evtchn;
 723         char protocol[64] = "";
 724         int err;
 725
 726         DPRINTK("%s", dev->otherend);
 727
 728         err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu",
 729                             &ring_ref, "event-channel", "%u", &evtchn, NULL);
 730         if (err) {
 731                 xenbus_dev_fatal(dev, err,
 732                                  "reading %s/ring-ref and event-channel",
 733                                  dev->otherend);
 734                 return err;
 735         }
 736
 737         be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
 738         err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
 739                             "%63s", protocol, NULL);
 740         if (err)
 741                 strcpy(protocol, "unspecified, assuming native");
 742         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
 743                 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
 744         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
 745                 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
 746         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
 747                 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
 748         else {
 749                 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
 750                 return -1;
 751         }
 752         pr_info(DRV_PFX "ring-ref %ld, event-channel %d, protocol %d (%s)\n",
 753                 ring_ref, evtchn, be->blkif->blk_protocol, protocol);
 754
 755         /* Map the shared frame, irq etc. */
 756         err = xen_blkif_map(be->blkif, ring_ref, evtchn);
 757         if (err) {
 758                 xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u",
 759                                  ring_ref, evtchn);
 760                 return err;
 761         }
 762
 763         return 0;
 764 }
 765
 766
 767 /* ** Driver Registration ** */
 768
 769
 770 static const struct xenbus_device_id xen_blkbk_ids[] = {
 771         { "vbd" },
 772         { "" }
 773 };
 774
 775
 776 static DEFINE_XENBUS_DRIVER(xen_blkbk, ,
 777         .probe = xen_blkbk_probe,
 778         .remove = xen_blkbk_remove,
 779         .otherend_changed = frontend_changed
 780 );
 781
 782
 783 int xen_blkif_xenbus_init(void)
 784 {
 785         return xenbus_register_backend(&xen_blkbk_driver);
 786 }