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