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 #define pr_fmt(fmt) "xen-blkback: " fmt
  18
  19 #include <stdarg.h>
  20 #include <linux/module.h>
  21 #include <linux/kthread.h>
  22 #include <xen/events.h>
  23 #include <xen/grant_table.h>
  24 #include "common.h"
  25
  26 /* Enlarge the array size in order to fully show blkback name. */
  27 #define BLKBACK_NAME_LEN (20)
  28 #define RINGREF_NAME_LEN (20)
  29
  30 struct backend_info {
  31         struct xenbus_device    *dev;
  32         struct xen_blkif        *blkif;
  33         struct xenbus_watch     backend_watch;
  34         unsigned                major;
  35         unsigned                minor;
  36         char                    *mode;
  37 };
  38
  39 static struct kmem_cache *xen_blkif_cachep;
  40 static void connect(struct backend_info *);
  41 static int connect_ring(struct backend_info *);
  42 static void backend_changed(struct xenbus_watch *, const char **,
  43                             unsigned int);
  44 static void xen_blkif_free(struct xen_blkif *blkif);
  45 static void xen_vbd_free(struct xen_vbd *vbd);
  46
  47 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be)
  48 {
  49         return be->dev;
  50 }
  51
  52 /*
  53  * The last request could free the device from softirq context and
  54  * xen_blkif_free() can sleep.
  55  */
  56 static void xen_blkif_deferred_free(struct work_struct *work)
  57 {
  58         struct xen_blkif *blkif;
  59
  60         blkif = container_of(work, struct xen_blkif, free_work);
  61         xen_blkif_free(blkif);
  62 }
  63
  64 static int blkback_name(struct xen_blkif *blkif, char *buf)
  65 {
  66         char *devpath, *devname;
  67         struct xenbus_device *dev = blkif->be->dev;
  68
  69         devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL);
  70         if (IS_ERR(devpath))
  71                 return PTR_ERR(devpath);
  72
  73         devname = strstr(devpath, "/dev/");
  74         if (devname != NULL)
  75                 devname += strlen("/dev/");
  76         else
  77                 devname  = devpath;
  78
  79         snprintf(buf, BLKBACK_NAME_LEN, "blkback.%d.%s", blkif->domid, devname);
  80         kfree(devpath);
  81
  82         return 0;
  83 }
  84
  85 static void xen_update_blkif_status(struct xen_blkif *blkif)
  86 {
  87         int err;
  88         char name[BLKBACK_NAME_LEN];
  89
  90         /* Not ready to connect? */
  91         if (!blkif->irq || !blkif->vbd.bdev)
  92                 return;
  93
  94         /* Already connected? */
  95         if (blkif->be->dev->state == XenbusStateConnected)
  96                 return;
  97
  98         /* Attempt to connect: exit if we fail to. */
  99         connect(blkif->be);
 100         if (blkif->be->dev->state != XenbusStateConnected)
 101                 return;
 102
 103         err = blkback_name(blkif, name);
 104         if (err) {
 105                 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name");
 106                 return;
 107         }
 108
 109         err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping);
 110         if (err) {
 111                 xenbus_dev_error(blkif->be->dev, err, "block flush");
 112                 return;
 113         }
 114         invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping);
 115
 116         blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, "%s", name);
 117         if (IS_ERR(blkif->xenblkd)) {
 118                 err = PTR_ERR(blkif->xenblkd);
 119                 blkif->xenblkd = NULL;
 120                 xenbus_dev_error(blkif->be->dev, err, "start xenblkd");
 121                 return;
 122         }
 123 }
 124
 125 static struct xen_blkif *xen_blkif_alloc(domid_t domid)
 126 {
 127         struct xen_blkif *blkif;
 128
 129         BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST);
 130
 131         blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL);
 132         if (!blkif)
 133                 return ERR_PTR(-ENOMEM);
 134
 135         blkif->domid = domid;
 136         spin_lock_init(&blkif->blk_ring_lock);
 137         atomic_set(&blkif->refcnt, 1);
 138         init_waitqueue_head(&blkif->wq);
 139         init_completion(&blkif->drain_complete);
 140         atomic_set(&blkif->drain, 0);
 141         blkif->st_print = jiffies;
 142         blkif->persistent_gnts.rb_node = NULL;
 143         spin_lock_init(&blkif->free_pages_lock);
 144         INIT_LIST_HEAD(&blkif->free_pages);
 145         INIT_LIST_HEAD(&blkif->persistent_purge_list);
 146         blkif->free_pages_num = 0;
 147         atomic_set(&blkif->persistent_gnt_in_use, 0);
 148         atomic_set(&blkif->inflight, 0);
 149         INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants);
 150
 151         INIT_LIST_HEAD(&blkif->pending_free);
 152         INIT_WORK(&blkif->free_work, xen_blkif_deferred_free);
 153         spin_lock_init(&blkif->pending_free_lock);
 154         init_waitqueue_head(&blkif->pending_free_wq);
 155         init_waitqueue_head(&blkif->shutdown_wq);
 156
 157         return blkif;
 158 }
 159
 160 static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref,
 161                          unsigned int nr_grefs, unsigned int evtchn)
 162 {
 163         int err;
 164
 165         /* Already connected through? */
 166         if (blkif->irq)
 167                 return 0;
 168
 169         err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs,
 170                                      &blkif->blk_ring);
 171         if (err < 0)
 172                 return err;
 173
 174         switch (blkif->blk_protocol) {
 175         case BLKIF_PROTOCOL_NATIVE:
 176         {
 177                 struct blkif_sring *sring;
 178                 sring = (struct blkif_sring *)blkif->blk_ring;
 179                 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE * nr_grefs);
 180                 break;
 181         }
 182         case BLKIF_PROTOCOL_X86_32:
 183         {
 184                 struct blkif_x86_32_sring *sring_x86_32;
 185                 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring;
 186                 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE * nr_grefs);
 187                 break;
 188         }
 189         case BLKIF_PROTOCOL_X86_64:
 190         {
 191                 struct blkif_x86_64_sring *sring_x86_64;
 192                 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring;
 193                 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE * nr_grefs);
 194                 break;
 195         }
 196         default:
 197                 BUG();
 198         }
 199
 200         err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn,
 201                                                     xen_blkif_be_int, 0,
 202                                                     "blkif-backend", blkif);
 203         if (err < 0) {
 204                 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
 205                 blkif->blk_rings.common.sring = NULL;
 206                 return err;
 207         }
 208         blkif->irq = err;
 209
 210         return 0;
 211 }
 212
 213 static int xen_blkif_disconnect(struct xen_blkif *blkif)
 214 {
 215         struct pending_req *req, *n;
 216         int i = 0, j;
 217
 218         if (blkif->xenblkd) {
 219                 kthread_stop(blkif->xenblkd);
 220                 wake_up(&blkif->shutdown_wq);
 221                 blkif->xenblkd = NULL;
 222         }
 223
 224         /* The above kthread_stop() guarantees that at this point we
 225          * don't have any discard_io or other_io requests. So, checking
 226          * for inflight IO is enough.
 227          */
 228         if (atomic_read(&blkif->inflight) > 0)
 229                 return -EBUSY;
 230
 231         if (blkif->irq) {
 232                 unbind_from_irqhandler(blkif->irq, blkif);
 233                 blkif->irq = 0;
 234         }
 235
 236         if (blkif->blk_rings.common.sring) {
 237                 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring);
 238                 blkif->blk_rings.common.sring = NULL;
 239         }
 240
 241         /* Remove all persistent grants and the cache of ballooned pages. */
 242         xen_blkbk_free_caches(blkif);
 243
 244         /* Check that there is no request in use */
 245         list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) {
 246                 list_del(&req->free_list);
 247
 248                 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++)
 249                         kfree(req->segments[j]);
 250
 251                 for (j = 0; j < MAX_INDIRECT_PAGES; j++)
 252                         kfree(req->indirect_pages[j]);
 253
 254                 kfree(req);
 255                 i++;
 256         }
 257
 258         WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
 259         blkif->nr_ring_pages = 0;
 260
 261         return 0;
 262 }
 263
 264 static void xen_blkif_free(struct xen_blkif *blkif)
 265 {
 266
 267         xen_blkif_disconnect(blkif);
 268         xen_vbd_free(&blkif->vbd);
 269
 270         /* Make sure everything is drained before shutting down */
 271         BUG_ON(blkif->persistent_gnt_c != 0);
 272         BUG_ON(atomic_read(&blkif->persistent_gnt_in_use) != 0);
 273         BUG_ON(blkif->free_pages_num != 0);
 274         BUG_ON(!list_empty(&blkif->persistent_purge_list));
 275         BUG_ON(!list_empty(&blkif->free_pages));
 276         BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts));
 277
 278         kmem_cache_free(xen_blkif_cachep, blkif);
 279 }
 280
 281 int __init xen_blkif_interface_init(void)
 282 {
 283         xen_blkif_cachep = kmem_cache_create("blkif_cache",
 284                                              sizeof(struct xen_blkif),
 285                                              0, 0, NULL);
 286         if (!xen_blkif_cachep)
 287                 return -ENOMEM;
 288
 289         return 0;
 290 }
 291
 292 /*
 293  *  sysfs interface for VBD I/O requests
 294  */
 295
 296 #define VBD_SHOW(name, format, args...)                                 \
 297         static ssize_t show_##name(struct device *_dev,                 \
 298                                    struct device_attribute *attr,       \
 299                                    char *buf)                           \
 300         {                                                               \
 301                 struct xenbus_device *dev = to_xenbus_device(_dev);     \
 302                 struct backend_info *be = dev_get_drvdata(&dev->dev);   \
 303                                                                         \
 304                 return sprintf(buf, format, ##args);                    \
 305         }                                                               \
 306         static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
 307
 308 VBD_SHOW(oo_req,  "%llu\n", be->blkif->st_oo_req);
 309 VBD_SHOW(rd_req,  "%llu\n", be->blkif->st_rd_req);
 310 VBD_SHOW(wr_req,  "%llu\n", be->blkif->st_wr_req);
 311 VBD_SHOW(f_req,  "%llu\n", be->blkif->st_f_req);
 312 VBD_SHOW(ds_req,  "%llu\n", be->blkif->st_ds_req);
 313 VBD_SHOW(rd_sect, "%llu\n", be->blkif->st_rd_sect);
 314 VBD_SHOW(wr_sect, "%llu\n", be->blkif->st_wr_sect);
 315
 316 static struct attribute *xen_vbdstat_attrs[] = {
 317         &dev_attr_oo_req.attr,
 318         &dev_attr_rd_req.attr,
 319         &dev_attr_wr_req.attr,
 320         &dev_attr_f_req.attr,
 321         &dev_attr_ds_req.attr,
 322         &dev_attr_rd_sect.attr,
 323         &dev_attr_wr_sect.attr,
 324         NULL
 325 };
 326
 327 static struct attribute_group xen_vbdstat_group = {
 328         .name = "statistics",
 329         .attrs = xen_vbdstat_attrs,
 330 };
 331
 332 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor);
 333 VBD_SHOW(mode, "%s\n", be->mode);
 334
 335 static int xenvbd_sysfs_addif(struct xenbus_device *dev)
 336 {
 337         int error;
 338
 339         error = device_create_file(&dev->dev, &dev_attr_physical_device);
 340         if (error)
 341                 goto fail1;
 342
 343         error = device_create_file(&dev->dev, &dev_attr_mode);
 344         if (error)
 345                 goto fail2;
 346
 347         error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group);
 348         if (error)
 349                 goto fail3;
 350
 351         return 0;
 352
 353 fail3:  sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
 354 fail2:  device_remove_file(&dev->dev, &dev_attr_mode);
 355 fail1:  device_remove_file(&dev->dev, &dev_attr_physical_device);
 356         return error;
 357 }
 358
 359 static void xenvbd_sysfs_delif(struct xenbus_device *dev)
 360 {
 361         sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group);
 362         device_remove_file(&dev->dev, &dev_attr_mode);
 363         device_remove_file(&dev->dev, &dev_attr_physical_device);
 364 }
 365
 366
 367 static void xen_vbd_free(struct xen_vbd *vbd)
 368 {
 369         if (vbd->bdev)
 370                 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
 371         vbd->bdev = NULL;
 372 }
 373
 374 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle,
 375                           unsigned major, unsigned minor, int readonly,
 376                           int cdrom)
 377 {
 378         struct xen_vbd *vbd;
 379         struct block_device *bdev;
 380         struct request_queue *q;
 381
 382         vbd = &blkif->vbd;
 383         vbd->handle   = handle;
 384         vbd->readonly = readonly;
 385         vbd->type     = 0;
 386
 387         vbd->pdevice  = MKDEV(major, minor);
 388
 389         bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ?
 390                                  FMODE_READ : FMODE_WRITE, NULL);
 391
 392         if (IS_ERR(bdev)) {
 393                 pr_warn("xen_vbd_create: device %08x could not be opened\n",
 394                         vbd->pdevice);
 395                 return -ENOENT;
 396         }
 397
 398         vbd->bdev = bdev;
 399         if (vbd->bdev->bd_disk == NULL) {
 400                 pr_warn("xen_vbd_create: device %08x doesn't exist\n",
 401                         vbd->pdevice);
 402                 xen_vbd_free(vbd);
 403                 return -ENOENT;
 404         }
 405         vbd->size = vbd_sz(vbd);
 406
 407         if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
 408                 vbd->type |= VDISK_CDROM;
 409         if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
 410                 vbd->type |= VDISK_REMOVABLE;
 411
 412         q = bdev_get_queue(bdev);
 413         if (q && q->flush_flags)
 414                 vbd->flush_support = true;
 415
 416         if (q && blk_queue_secdiscard(q))
 417                 vbd->discard_secure = true;
 418
 419         pr_debug("Successful creation of handle=%04x (dom=%u)\n",
 420                 handle, blkif->domid);
 421         return 0;
 422 }
 423 static int xen_blkbk_remove(struct xenbus_device *dev)
 424 {
 425         struct backend_info *be = dev_get_drvdata(&dev->dev);
 426
 427         pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
 428
 429         if (be->major || be->minor)
 430                 xenvbd_sysfs_delif(dev);
 431
 432         if (be->backend_watch.node) {
 433                 unregister_xenbus_watch(&be->backend_watch);
 434                 kfree(be->backend_watch.node);
 435                 be->backend_watch.node = NULL;
 436         }
 437
 438         dev_set_drvdata(&dev->dev, NULL);
 439
 440         if (be->blkif) {
 441                 xen_blkif_disconnect(be->blkif);
 442                 xen_blkif_put(be->blkif);
 443         }
 444
 445         kfree(be->mode);
 446         kfree(be);
 447         return 0;
 448 }
 449
 450 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
 451                               struct backend_info *be, int state)
 452 {
 453         struct xenbus_device *dev = be->dev;
 454         int err;
 455
 456         err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache",
 457                             "%d", state);
 458         if (err)
 459                 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err);
 460
 461         return err;
 462 }
 463
 464 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be)
 465 {
 466         struct xenbus_device *dev = be->dev;
 467         struct xen_blkif *blkif = be->blkif;
 468         int err;
 469         int state = 0, discard_enable;
 470         struct block_device *bdev = be->blkif->vbd.bdev;
 471         struct request_queue *q = bdev_get_queue(bdev);
 472
 473         err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d",
 474                            &discard_enable);
 475         if (err == 1 && !discard_enable)
 476                 return;
 477
 478         if (blk_queue_discard(q)) {
 479                 err = xenbus_printf(xbt, dev->nodename,
 480                         "discard-granularity", "%u",
 481                         q->limits.discard_granularity);
 482                 if (err) {
 483                         dev_warn(&dev->dev, "writing discard-granularity (%d)", err);
 484                         return;
 485                 }
 486                 err = xenbus_printf(xbt, dev->nodename,
 487                         "discard-alignment", "%u",
 488                         q->limits.discard_alignment);
 489                 if (err) {
 490                         dev_warn(&dev->dev, "writing discard-alignment (%d)", err);
 491                         return;
 492                 }
 493                 state = 1;
 494                 /* Optional. */
 495                 err = xenbus_printf(xbt, dev->nodename,
 496                                     "discard-secure", "%d",
 497                                     blkif->vbd.discard_secure);
 498                 if (err) {
 499                         dev_warn(&dev->dev, "writing discard-secure (%d)", err);
 500                         return;
 501                 }
 502         }
 503         err = xenbus_printf(xbt, dev->nodename, "feature-discard",
 504                             "%d", state);
 505         if (err)
 506                 dev_warn(&dev->dev, "writing feature-discard (%d)", err);
 507 }
 508 int xen_blkbk_barrier(struct xenbus_transaction xbt,
 509                       struct backend_info *be, int state)
 510 {
 511         struct xenbus_device *dev = be->dev;
 512         int err;
 513
 514         err = xenbus_printf(xbt, dev->nodename, "feature-barrier",
 515                             "%d", state);
 516         if (err)
 517                 dev_warn(&dev->dev, "writing feature-barrier (%d)", err);
 518
 519         return err;
 520 }
 521
 522 /*
 523  * Entry point to this code when a new device is created.  Allocate the basic
 524  * structures, and watch the store waiting for the hotplug scripts to tell us
 525  * the device's physical major and minor numbers.  Switch to InitWait.
 526  */
 527 static int xen_blkbk_probe(struct xenbus_device *dev,
 528                            const struct xenbus_device_id *id)
 529 {
 530         int err;
 531         struct backend_info *be = kzalloc(sizeof(struct backend_info),
 532                                           GFP_KERNEL);
 533
 534         /* match the pr_debug in xen_blkbk_remove */
 535         pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
 536
 537         if (!be) {
 538                 xenbus_dev_fatal(dev, -ENOMEM,
 539                                  "allocating backend structure");
 540                 return -ENOMEM;
 541         }
 542         be->dev = dev;
 543         dev_set_drvdata(&dev->dev, be);
 544
 545         be->blkif = xen_blkif_alloc(dev->otherend_id);
 546         if (IS_ERR(be->blkif)) {
 547                 err = PTR_ERR(be->blkif);
 548                 be->blkif = NULL;
 549                 xenbus_dev_fatal(dev, err, "creating block interface");
 550                 goto fail;
 551         }
 552
 553         /* setup back pointer */
 554         be->blkif->be = be;
 555
 556         err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed,
 557                                    "%s/%s", dev->nodename, "physical-device");
 558         if (err)
 559                 goto fail;
 560
 561         err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u",
 562                             xen_blkif_max_ring_order);
 563         if (err)
 564                 pr_warn("%s write out 'max-ring-page-order' failed\n", __func__);
 565
 566         err = xenbus_switch_state(dev, XenbusStateInitWait);
 567         if (err)
 568                 goto fail;
 569
 570         return 0;
 571
 572 fail:
 573         pr_warn("%s failed\n", __func__);
 574         xen_blkbk_remove(dev);
 575         return err;
 576 }
 577
 578
 579 /*
 580  * Callback received when the hotplug scripts have placed the physical-device
 581  * node.  Read it and the mode node, and create a vbd.  If the frontend is
 582  * ready, connect.
 583  */
 584 static void backend_changed(struct xenbus_watch *watch,
 585                             const char **vec, unsigned int len)
 586 {
 587         int err;
 588         unsigned major;
 589         unsigned minor;
 590         struct backend_info *be
 591                 = container_of(watch, struct backend_info, backend_watch);
 592         struct xenbus_device *dev = be->dev;
 593         int cdrom = 0;
 594         unsigned long handle;
 595         char *device_type;
 596
 597         pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id);
 598
 599         err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x",
 600                            &major, &minor);
 601         if (XENBUS_EXIST_ERR(err)) {
 602                 /*
 603                  * Since this watch will fire once immediately after it is
 604                  * registered, we expect this.  Ignore it, and wait for the
 605                  * hotplug scripts.
 606                  */
 607                 return;
 608         }
 609         if (err != 2) {
 610                 xenbus_dev_fatal(dev, err, "reading physical-device");
 611                 return;
 612         }
 613
 614         if (be->major | be->minor) {
 615                 if (be->major != major || be->minor != minor)
 616                         pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n",
 617                                 be->major, be->minor, major, minor);
 618                 return;
 619         }
 620
 621         be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL);
 622         if (IS_ERR(be->mode)) {
 623                 err = PTR_ERR(be->mode);
 624                 be->mode = NULL;
 625                 xenbus_dev_fatal(dev, err, "reading mode");
 626                 return;
 627         }
 628
 629         device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL);
 630         if (!IS_ERR(device_type)) {
 631                 cdrom = strcmp(device_type, "cdrom") == 0;
 632                 kfree(device_type);
 633         }
 634
 635         /* Front end dir is a number, which is used as the handle. */
 636         err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle);
 637         if (err)
 638                 return;
 639
 640         be->major = major;
 641         be->minor = minor;
 642
 643         err = xen_vbd_create(be->blkif, handle, major, minor,
 644                              !strchr(be->mode, 'w'), cdrom);
 645
 646         if (err)
 647                 xenbus_dev_fatal(dev, err, "creating vbd structure");
 648         else {
 649                 err = xenvbd_sysfs_addif(dev);
 650                 if (err) {
 651                         xen_vbd_free(&be->blkif->vbd);
 652                         xenbus_dev_fatal(dev, err, "creating sysfs entries");
 653                 }
 654         }
 655
 656         if (err) {
 657                 kfree(be->mode);
 658                 be->mode = NULL;
 659                 be->major = 0;
 660                 be->minor = 0;
 661         } else {
 662                 /* We're potentially connected now */
 663                 xen_update_blkif_status(be->blkif);
 664         }
 665 }
 666
 667
 668 /*
 669  * Callback received when the frontend's state changes.
 670  */
 671 static void frontend_changed(struct xenbus_device *dev,
 672                              enum xenbus_state frontend_state)
 673 {
 674         struct backend_info *be = dev_get_drvdata(&dev->dev);
 675         int err;
 676
 677         pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state));
 678
 679         switch (frontend_state) {
 680         case XenbusStateInitialising:
 681                 if (dev->state == XenbusStateClosed) {
 682                         pr_info("%s: prepare for reconnect\n", dev->nodename);
 683                         xenbus_switch_state(dev, XenbusStateInitWait);
 684                 }
 685                 break;
 686
 687         case XenbusStateInitialised:
 688         case XenbusStateConnected:
 689                 /*
 690                  * Ensure we connect even when two watches fire in
 691                  * close succession and we miss the intermediate value
 692                  * of frontend_state.
 693                  */
 694                 if (dev->state == XenbusStateConnected)
 695                         break;
 696
 697                 /*
 698                  * Enforce precondition before potential leak point.
 699                  * xen_blkif_disconnect() is idempotent.
 700                  */
 701                 err = xen_blkif_disconnect(be->blkif);
 702                 if (err) {
 703                         xenbus_dev_fatal(dev, err, "pending I/O");
 704                         break;
 705                 }
 706
 707                 err = connect_ring(be);
 708                 if (err)
 709                         break;
 710                 xen_update_blkif_status(be->blkif);
 711                 break;
 712
 713         case XenbusStateClosing:
 714                 xenbus_switch_state(dev, XenbusStateClosing);
 715                 break;
 716
 717         case XenbusStateClosed:
 718                 xen_blkif_disconnect(be->blkif);
 719                 xenbus_switch_state(dev, XenbusStateClosed);
 720                 if (xenbus_dev_is_online(dev))
 721                         break;
 722                 /* fall through if not online */
 723         case XenbusStateUnknown:
 724                 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */
 725                 device_unregister(&dev->dev);
 726                 break;
 727
 728         default:
 729                 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend",
 730                                  frontend_state);
 731                 break;
 732         }
 733 }
 734
 735
 736 /* ** Connection ** */
 737
 738
 739 /*
 740  * Write the physical details regarding the block device to the store, and
 741  * switch to Connected state.
 742  */
 743 static void connect(struct backend_info *be)
 744 {
 745         struct xenbus_transaction xbt;
 746         int err;
 747         struct xenbus_device *dev = be->dev;
 748
 749         pr_debug("%s %s\n", __func__, dev->otherend);
 750
 751         /* Supply the information about the device the frontend needs */
 752 again:
 753         err = xenbus_transaction_start(&xbt);
 754         if (err) {
 755                 xenbus_dev_fatal(dev, err, "starting transaction");
 756                 return;
 757         }
 758
 759         /* If we can't advertise it is OK. */
 760         xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support);
 761
 762         xen_blkbk_discard(xbt, be);
 763
 764         xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
 765
 766         err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1);
 767         if (err) {
 768                 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent",
 769                                  dev->nodename);
 770                 goto abort;
 771         }
 772         err = xenbus_printf(xbt, dev->nodename, "feature-max-indirect-segments", "%u",
 773                             MAX_INDIRECT_SEGMENTS);
 774         if (err)
 775                 dev_warn(&dev->dev, "writing %s/feature-max-indirect-segments (%d)",
 776                          dev->nodename, err);
 777
 778         err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu",
 779                             (unsigned long long)vbd_sz(&be->blkif->vbd));
 780         if (err) {
 781                 xenbus_dev_fatal(dev, err, "writing %s/sectors",
 782                                  dev->nodename);
 783                 goto abort;
 784         }
 785
 786         /* FIXME: use a typename instead */
 787         err = xenbus_printf(xbt, dev->nodename, "info", "%u",
 788                             be->blkif->vbd.type |
 789                             (be->blkif->vbd.readonly ? VDISK_READONLY : 0));
 790         if (err) {
 791                 xenbus_dev_fatal(dev, err, "writing %s/info",
 792                                  dev->nodename);
 793                 goto abort;
 794         }
 795         err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu",
 796                             (unsigned long)
 797                             bdev_logical_block_size(be->blkif->vbd.bdev));
 798         if (err) {
 799                 xenbus_dev_fatal(dev, err, "writing %s/sector-size",
 800                                  dev->nodename);
 801                 goto abort;
 802         }
 803         err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u",
 804                             bdev_physical_block_size(be->blkif->vbd.bdev));
 805         if (err)
 806                 xenbus_dev_error(dev, err, "writing %s/physical-sector-size",
 807                                  dev->nodename);
 808
 809         err = xenbus_transaction_end(xbt, 0);
 810         if (err == -EAGAIN)
 811                 goto again;
 812         if (err)
 813                 xenbus_dev_fatal(dev, err, "ending transaction");
 814
 815         err = xenbus_switch_state(dev, XenbusStateConnected);
 816         if (err)
 817                 xenbus_dev_fatal(dev, err, "%s: switching to Connected state",
 818                                  dev->nodename);
 819
 820         return;
 821  abort:
 822         xenbus_transaction_end(xbt, 1);
 823 }
 824
 825
 826 static int connect_ring(struct backend_info *be)
 827 {
 828         struct xenbus_device *dev = be->dev;
 829         unsigned int ring_ref[XENBUS_MAX_RING_PAGES];
 830         unsigned int evtchn, nr_grefs, ring_page_order;
 831         unsigned int pers_grants;
 832         char protocol[64] = "";
 833         struct pending_req *req, *n;
 834         int err, i, j;
 835
 836         pr_debug("%s %s\n", __func__, dev->otherend);
 837
 838         err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel", "%u",
 839                           &evtchn);
 840         if (err != 1) {
 841                 err = -EINVAL;
 842                 xenbus_dev_fatal(dev, err, "reading %s/event-channel",
 843                                  dev->otherend);
 844                 return err;
 845         }
 846         pr_info("event-channel %u\n", evtchn);
 847
 848         err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
 849                           &ring_page_order);
 850         if (err != 1) {
 851                 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref",
 852                                   "%u", &ring_ref[0]);
 853                 if (err != 1) {
 854                         err = -EINVAL;
 855                         xenbus_dev_fatal(dev, err, "reading %s/ring-ref",
 856                                          dev->otherend);
 857                         return err;
 858                 }
 859                 nr_grefs = 1;
 860                 pr_info("%s:using single page: ring-ref %d\n", dev->otherend,
 861                         ring_ref[0]);
 862         } else {
 863                 unsigned int i;
 864
 865                 if (ring_page_order > xen_blkif_max_ring_order) {
 866                         err = -EINVAL;
 867                         xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d",
 868                                          dev->otherend, ring_page_order,
 869                                          xen_blkif_max_ring_order);
 870                         return err;
 871                 }
 872
 873                 nr_grefs = 1 << ring_page_order;
 874                 for (i = 0; i < nr_grefs; i++) {
 875                         char ring_ref_name[RINGREF_NAME_LEN];
 876
 877                         snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
 878                         err = xenbus_scanf(XBT_NIL, dev->otherend, ring_ref_name,
 879                                            "%u", &ring_ref[i]);
 880                         if (err != 1) {
 881                                 err = -EINVAL;
 882                                 xenbus_dev_fatal(dev, err, "reading %s/%s",
 883                                                  dev->otherend, ring_ref_name);
 884                                 return err;
 885                         }
 886                         pr_info("ring-ref%u: %u\n", i, ring_ref[i]);
 887                 }
 888         }
 889
 890         be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
 891         err = xenbus_gather(XBT_NIL, dev->otherend, "protocol",
 892                             "%63s", protocol, NULL);
 893         if (err)
 894                 strcpy(protocol, "unspecified, assuming default");
 895         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
 896                 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
 897         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
 898                 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
 899         else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
 900                 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
 901         else {
 902                 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
 903                 return -1;
 904         }
 905         err = xenbus_gather(XBT_NIL, dev->otherend,
 906                             "feature-persistent", "%u",
 907                             &pers_grants, NULL);
 908         if (err)
 909                 pers_grants = 0;
 910
 911         be->blkif->vbd.feature_gnt_persistent = pers_grants;
 912         be->blkif->vbd.overflow_max_grants = 0;
 913         be->blkif->nr_ring_pages = nr_grefs;
 914
 915         pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n",
 916                 nr_grefs, evtchn, be->blkif->blk_protocol, protocol,
 917                 pers_grants ? "persistent grants" : "");
 918
 919         for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
 920                 req = kzalloc(sizeof(*req), GFP_KERNEL);
 921                 if (!req)
 922                         goto fail;
 923                 list_add_tail(&req->free_list, &be->blkif->pending_free);
 924                 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
 925                         req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL);
 926                         if (!req->segments[j])
 927                                 goto fail;
 928                 }
 929                 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
 930                         req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]),
 931                                                          GFP_KERNEL);
 932                         if (!req->indirect_pages[j])
 933                                 goto fail;
 934                 }
 935         }
 936
 937         /* Map the shared frame, irq etc. */
 938         err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn);
 939         if (err) {
 940                 xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn);
 941                 return err;
 942         }
 943
 944         return 0;
 945
 946 fail:
 947         list_for_each_entry_safe(req, n, &be->blkif->pending_free, free_list) {
 948                 list_del(&req->free_list);
 949                 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) {
 950                         if (!req->segments[j])
 951                                 break;
 952                         kfree(req->segments[j]);
 953                 }
 954                 for (j = 0; j < MAX_INDIRECT_PAGES; j++) {
 955                         if (!req->indirect_pages[j])
 956                                 break;
 957                         kfree(req->indirect_pages[j]);
 958                 }
 959                 kfree(req);
 960         }
 961         return -ENOMEM;
 962 }
 963
 964 static const struct xenbus_device_id xen_blkbk_ids[] = {
 965         { "vbd" },
 966         { "" }
 967 };
 968
 969 static struct xenbus_driver xen_blkbk_driver = {
 970         .ids  = xen_blkbk_ids,
 971         .probe = xen_blkbk_probe,
 972         .remove = xen_blkbk_remove,
 973         .otherend_changed = frontend_changed
 974 };
 975
 976 int xen_blkif_xenbus_init(void)
 977 {
 978         return xenbus_register_backend(&xen_blkbk_driver);
 979 }