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 blkif->persistent_gnts.rb_node = NULL; 121 122 return blkif; 123 } 124 125 static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page, 126 unsigned int evtchn) 127 { 128 int err; 129 130 /* Already connected through? */ 131 if (blkif->irq) 132 return 0; 133 134 err = xenbus_map_ring_valloc(blkif->be->dev, shared_page, &blkif->blk_ring); 135 if (err < 0) 136 return err; 137 138 switch (blkif->blk_protocol) { 139 case BLKIF_PROTOCOL_NATIVE: 140 { 141 struct blkif_sring *sring; 142 sring = (struct blkif_sring *)blkif->blk_ring; 143 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE); 144 break; 145 } 146 case BLKIF_PROTOCOL_X86_32: 147 { 148 struct blkif_x86_32_sring *sring_x86_32; 149 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring; 150 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE); 151 break; 152 } 153 case BLKIF_PROTOCOL_X86_64: 154 { 155 struct blkif_x86_64_sring *sring_x86_64; 156 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring; 157 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE); 158 break; 159 } 160 default: 161 BUG(); 162 } 163 164 err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn, 165 xen_blkif_be_int, 0, 166 "blkif-backend", blkif); 167 if (err < 0) { 168 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); 169 blkif->blk_rings.common.sring = NULL; 170 return err; 171 } 172 blkif->irq = err; 173 174 return 0; 175 } 176 177 static void xen_blkif_disconnect(struct xen_blkif *blkif) 178 { 179 if (blkif->xenblkd) { 180 kthread_stop(blkif->xenblkd); 181 blkif->xenblkd = NULL; 182 } 183 184 atomic_dec(&blkif->refcnt); 185 wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0); 186 atomic_inc(&blkif->refcnt); 187 188 if (blkif->irq) { 189 unbind_from_irqhandler(blkif->irq, blkif); 190 blkif->irq = 0; 191 } 192 193 if (blkif->blk_rings.common.sring) { 194 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); 195 blkif->blk_rings.common.sring = NULL; 196 } 197 } 198 199 static void xen_blkif_free(struct xen_blkif *blkif) 200 { 201 if (!atomic_dec_and_test(&blkif->refcnt)) 202 BUG(); 203 kmem_cache_free(xen_blkif_cachep, blkif); 204 } 205 206 int __init xen_blkif_interface_init(void) 207 { 208 xen_blkif_cachep = kmem_cache_create("blkif_cache", 209 sizeof(struct xen_blkif), 210 0, 0, NULL); 211 if (!xen_blkif_cachep) 212 return -ENOMEM; 213 214 return 0; 215 } 216 217 /* 218 * sysfs interface for VBD I/O requests 219 */ 220 221 #define VBD_SHOW(name, format, args...) \ 222 static ssize_t show_##name(struct device *_dev, \ 223 struct device_attribute *attr, \ 224 char *buf) \ 225 { \ 226 struct xenbus_device *dev = to_xenbus_device(_dev); \ 227 struct backend_info *be = dev_get_drvdata(&dev->dev); \ 228 \ 229 return sprintf(buf, format, ##args); \ 230 } \ 231 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) 232 233 VBD_SHOW(oo_req, "%d\n", be->blkif->st_oo_req); 234 VBD_SHOW(rd_req, "%d\n", be->blkif->st_rd_req); 235 VBD_SHOW(wr_req, "%d\n", be->blkif->st_wr_req); 236 VBD_SHOW(f_req, "%d\n", be->blkif->st_f_req); 237 VBD_SHOW(ds_req, "%d\n", be->blkif->st_ds_req); 238 VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect); 239 VBD_SHOW(wr_sect, "%d\n", be->blkif->st_wr_sect); 240 241 static struct attribute *xen_vbdstat_attrs[] = { 242 &dev_attr_oo_req.attr, 243 &dev_attr_rd_req.attr, 244 &dev_attr_wr_req.attr, 245 &dev_attr_f_req.attr, 246 &dev_attr_ds_req.attr, 247 &dev_attr_rd_sect.attr, 248 &dev_attr_wr_sect.attr, 249 NULL 250 }; 251 252 static struct attribute_group xen_vbdstat_group = { 253 .name = "statistics", 254 .attrs = xen_vbdstat_attrs, 255 }; 256 257 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor); 258 VBD_SHOW(mode, "%s\n", be->mode); 259 260 static int xenvbd_sysfs_addif(struct xenbus_device *dev) 261 { 262 int error; 263 264 error = device_create_file(&dev->dev, &dev_attr_physical_device); 265 if (error) 266 goto fail1; 267 268 error = device_create_file(&dev->dev, &dev_attr_mode); 269 if (error) 270 goto fail2; 271 272 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group); 273 if (error) 274 goto fail3; 275 276 return 0; 277 278 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 279 fail2: device_remove_file(&dev->dev, &dev_attr_mode); 280 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device); 281 return error; 282 } 283 284 static void xenvbd_sysfs_delif(struct xenbus_device *dev) 285 { 286 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 287 device_remove_file(&dev->dev, &dev_attr_mode); 288 device_remove_file(&dev->dev, &dev_attr_physical_device); 289 } 290 291 292 static void xen_vbd_free(struct xen_vbd *vbd) 293 { 294 if (vbd->bdev) 295 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE); 296 vbd->bdev = NULL; 297 } 298 299 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, 300 unsigned major, unsigned minor, int readonly, 301 int cdrom) 302 { 303 struct xen_vbd *vbd; 304 struct block_device *bdev; 305 struct request_queue *q; 306 307 vbd = &blkif->vbd; 308 vbd->handle = handle; 309 vbd->readonly = readonly; 310 vbd->type = 0; 311 312 vbd->pdevice = MKDEV(major, minor); 313 314 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ? 315 FMODE_READ : FMODE_WRITE, NULL); 316 317 if (IS_ERR(bdev)) { 318 DPRINTK("xen_vbd_create: device %08x could not be opened.\n", 319 vbd->pdevice); 320 return -ENOENT; 321 } 322 323 vbd->bdev = bdev; 324 if (vbd->bdev->bd_disk == NULL) { 325 DPRINTK("xen_vbd_create: device %08x doesn't exist.\n", 326 vbd->pdevice); 327 xen_vbd_free(vbd); 328 return -ENOENT; 329 } 330 vbd->size = vbd_sz(vbd); 331 332 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom) 333 vbd->type |= VDISK_CDROM; 334 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE) 335 vbd->type |= VDISK_REMOVABLE; 336 337 q = bdev_get_queue(bdev); 338 if (q && q->flush_flags) 339 vbd->flush_support = true; 340 341 if (q && blk_queue_secdiscard(q)) 342 vbd->discard_secure = true; 343 344 DPRINTK("Successful creation of handle=%04x (dom=%u)\n", 345 handle, blkif->domid); 346 return 0; 347 } 348 static int xen_blkbk_remove(struct xenbus_device *dev) 349 { 350 struct backend_info *be = dev_get_drvdata(&dev->dev); 351 352 DPRINTK(""); 353 354 if (be->major || be->minor) 355 xenvbd_sysfs_delif(dev); 356 357 if (be->backend_watch.node) { 358 unregister_xenbus_watch(&be->backend_watch); 359 kfree(be->backend_watch.node); 360 be->backend_watch.node = NULL; 361 } 362 363 if (be->blkif) { 364 xen_blkif_disconnect(be->blkif); 365 xen_vbd_free(&be->blkif->vbd); 366 xen_blkif_free(be->blkif); 367 be->blkif = NULL; 368 } 369 370 kfree(be); 371 dev_set_drvdata(&dev->dev, NULL); 372 return 0; 373 } 374 375 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt, 376 struct backend_info *be, int state) 377 { 378 struct xenbus_device *dev = be->dev; 379 int err; 380 381 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache", 382 "%d", state); 383 if (err) 384 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err); 385 386 return err; 387 } 388 389 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be) 390 { 391 struct xenbus_device *dev = be->dev; 392 struct xen_blkif *blkif = be->blkif; 393 int err; 394 int state = 0; 395 struct block_device *bdev = be->blkif->vbd.bdev; 396 struct request_queue *q = bdev_get_queue(bdev); 397 398 if (blk_queue_discard(q)) { 399 err = xenbus_printf(xbt, dev->nodename, 400 "discard-granularity", "%u", 401 q->limits.discard_granularity); 402 if (err) { 403 dev_warn(&dev->dev, "writing discard-granularity (%d)", err); 404 return; 405 } 406 err = xenbus_printf(xbt, dev->nodename, 407 "discard-alignment", "%u", 408 q->limits.discard_alignment); 409 if (err) { 410 dev_warn(&dev->dev, "writing discard-alignment (%d)", err); 411 return; 412 } 413 state = 1; 414 /* Optional. */ 415 err = xenbus_printf(xbt, dev->nodename, 416 "discard-secure", "%d", 417 blkif->vbd.discard_secure); 418 if (err) { 419 dev_warn(&dev->dev, "writing discard-secure (%d)", err); 420 return; 421 } 422 } 423 err = xenbus_printf(xbt, dev->nodename, "feature-discard", 424 "%d", state); 425 if (err) 426 dev_warn(&dev->dev, "writing feature-discard (%d)", err); 427 } 428 int xen_blkbk_barrier(struct xenbus_transaction xbt, 429 struct backend_info *be, int state) 430 { 431 struct xenbus_device *dev = be->dev; 432 int err; 433 434 err = xenbus_printf(xbt, dev->nodename, "feature-barrier", 435 "%d", state); 436 if (err) 437 dev_warn(&dev->dev, "writing feature-barrier (%d)", err); 438 439 return err; 440 } 441 442 /* 443 * Entry point to this code when a new device is created. Allocate the basic 444 * structures, and watch the store waiting for the hotplug scripts to tell us 445 * the device's physical major and minor numbers. Switch to InitWait. 446 */ 447 static int xen_blkbk_probe(struct xenbus_device *dev, 448 const struct xenbus_device_id *id) 449 { 450 int err; 451 struct backend_info *be = kzalloc(sizeof(struct backend_info), 452 GFP_KERNEL); 453 if (!be) { 454 xenbus_dev_fatal(dev, -ENOMEM, 455 "allocating backend structure"); 456 return -ENOMEM; 457 } 458 be->dev = dev; 459 dev_set_drvdata(&dev->dev, be); 460 461 be->blkif = xen_blkif_alloc(dev->otherend_id); 462 if (IS_ERR(be->blkif)) { 463 err = PTR_ERR(be->blkif); 464 be->blkif = NULL; 465 xenbus_dev_fatal(dev, err, "creating block interface"); 466 goto fail; 467 } 468 469 /* setup back pointer */ 470 be->blkif->be = be; 471 472 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed, 473 "%s/%s", dev->nodename, "physical-device"); 474 if (err) 475 goto fail; 476 477 err = xenbus_switch_state(dev, XenbusStateInitWait); 478 if (err) 479 goto fail; 480 481 return 0; 482 483 fail: 484 DPRINTK("failed"); 485 xen_blkbk_remove(dev); 486 return err; 487 } 488 489 490 /* 491 * Callback received when the hotplug scripts have placed the physical-device 492 * node. Read it and the mode node, and create a vbd. If the frontend is 493 * ready, connect. 494 */ 495 static void backend_changed(struct xenbus_watch *watch, 496 const char **vec, unsigned int len) 497 { 498 int err; 499 unsigned major; 500 unsigned minor; 501 struct backend_info *be 502 = container_of(watch, struct backend_info, backend_watch); 503 struct xenbus_device *dev = be->dev; 504 int cdrom = 0; 505 char *device_type; 506 507 DPRINTK(""); 508 509 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x", 510 &major, &minor); 511 if (XENBUS_EXIST_ERR(err)) { 512 /* 513 * Since this watch will fire once immediately after it is 514 * registered, we expect this. Ignore it, and wait for the 515 * hotplug scripts. 516 */ 517 return; 518 } 519 if (err != 2) { 520 xenbus_dev_fatal(dev, err, "reading physical-device"); 521 return; 522 } 523 524 if ((be->major || be->minor) && 525 ((be->major != major) || (be->minor != minor))) { 526 pr_warn(DRV_PFX "changing physical device (from %x:%x to %x:%x) not supported.\n", 527 be->major, be->minor, major, minor); 528 return; 529 } 530 531 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL); 532 if (IS_ERR(be->mode)) { 533 err = PTR_ERR(be->mode); 534 be->mode = NULL; 535 xenbus_dev_fatal(dev, err, "reading mode"); 536 return; 537 } 538 539 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL); 540 if (!IS_ERR(device_type)) { 541 cdrom = strcmp(device_type, "cdrom") == 0; 542 kfree(device_type); 543 } 544 545 if (be->major == 0 && be->minor == 0) { 546 /* Front end dir is a number, which is used as the handle. */ 547 548 char *p = strrchr(dev->otherend, '/') + 1; 549 long handle; 550 err = strict_strtoul(p, 0, &handle); 551 if (err) 552 return; 553 554 be->major = major; 555 be->minor = minor; 556 557 err = xen_vbd_create(be->blkif, handle, major, minor, 558 (NULL == strchr(be->mode, 'w')), cdrom); 559 if (err) { 560 be->major = 0; 561 be->minor = 0; 562 xenbus_dev_fatal(dev, err, "creating vbd structure"); 563 return; 564 } 565 566 err = xenvbd_sysfs_addif(dev); 567 if (err) { 568 xen_vbd_free(&be->blkif->vbd); 569 be->major = 0; 570 be->minor = 0; 571 xenbus_dev_fatal(dev, err, "creating sysfs entries"); 572 return; 573 } 574 575 /* We're potentially connected now */ 576 xen_update_blkif_status(be->blkif); 577 } 578 } 579 580 581 /* 582 * Callback received when the frontend's state changes. 583 */ 584 static void frontend_changed(struct xenbus_device *dev, 585 enum xenbus_state frontend_state) 586 { 587 struct backend_info *be = dev_get_drvdata(&dev->dev); 588 int err; 589 590 DPRINTK("%s", xenbus_strstate(frontend_state)); 591 592 switch (frontend_state) { 593 case XenbusStateInitialising: 594 if (dev->state == XenbusStateClosed) { 595 pr_info(DRV_PFX "%s: prepare for reconnect\n", 596 dev->nodename); 597 xenbus_switch_state(dev, XenbusStateInitWait); 598 } 599 break; 600 601 case XenbusStateInitialised: 602 case XenbusStateConnected: 603 /* 604 * Ensure we connect even when two watches fire in 605 * close succession and we miss the intermediate value 606 * of frontend_state. 607 */ 608 if (dev->state == XenbusStateConnected) 609 break; 610 611 /* 612 * Enforce precondition before potential leak point. 613 * xen_blkif_disconnect() is idempotent. 614 */ 615 xen_blkif_disconnect(be->blkif); 616 617 err = connect_ring(be); 618 if (err) 619 break; 620 xen_update_blkif_status(be->blkif); 621 break; 622 623 case XenbusStateClosing: 624 xenbus_switch_state(dev, XenbusStateClosing); 625 break; 626 627 case XenbusStateClosed: 628 xen_blkif_disconnect(be->blkif); 629 xenbus_switch_state(dev, XenbusStateClosed); 630 if (xenbus_dev_is_online(dev)) 631 break; 632 /* fall through if not online */ 633 case XenbusStateUnknown: 634 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */ 635 device_unregister(&dev->dev); 636 break; 637 638 default: 639 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", 640 frontend_state); 641 break; 642 } 643 } 644 645 646 /* ** Connection ** */ 647 648 649 /* 650 * Write the physical details regarding the block device to the store, and 651 * switch to Connected state. 652 */ 653 static void connect(struct backend_info *be) 654 { 655 struct xenbus_transaction xbt; 656 int err; 657 struct xenbus_device *dev = be->dev; 658 659 DPRINTK("%s", dev->otherend); 660 661 /* Supply the information about the device the frontend needs */ 662 again: 663 err = xenbus_transaction_start(&xbt); 664 if (err) { 665 xenbus_dev_fatal(dev, err, "starting transaction"); 666 return; 667 } 668 669 /* If we can't advertise it is OK. */ 670 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support); 671 672 xen_blkbk_discard(xbt, be); 673 674 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); 675 676 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1); 677 if (err) { 678 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", 679 dev->nodename); 680 goto abort; 681 } 682 683 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 684 (unsigned long long)vbd_sz(&be->blkif->vbd)); 685 if (err) { 686 xenbus_dev_fatal(dev, err, "writing %s/sectors", 687 dev->nodename); 688 goto abort; 689 } 690 691 /* FIXME: use a typename instead */ 692 err = xenbus_printf(xbt, dev->nodename, "info", "%u", 693 be->blkif->vbd.type | 694 (be->blkif->vbd.readonly ? VDISK_READONLY : 0)); 695 if (err) { 696 xenbus_dev_fatal(dev, err, "writing %s/info", 697 dev->nodename); 698 goto abort; 699 } 700 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu", 701 (unsigned long) 702 bdev_logical_block_size(be->blkif->vbd.bdev)); 703 if (err) { 704 xenbus_dev_fatal(dev, err, "writing %s/sector-size", 705 dev->nodename); 706 goto abort; 707 } 708 709 err = xenbus_transaction_end(xbt, 0); 710 if (err == -EAGAIN) 711 goto again; 712 if (err) 713 xenbus_dev_fatal(dev, err, "ending transaction"); 714 715 err = xenbus_switch_state(dev, XenbusStateConnected); 716 if (err) 717 xenbus_dev_fatal(dev, err, "%s: switching to Connected state", 718 dev->nodename); 719 720 return; 721 abort: 722 xenbus_transaction_end(xbt, 1); 723 } 724 725 726 static int connect_ring(struct backend_info *be) 727 { 728 struct xenbus_device *dev = be->dev; 729 unsigned long ring_ref; 730 unsigned int evtchn; 731 unsigned int pers_grants; 732 char protocol[64] = ""; 733 int err; 734 735 DPRINTK("%s", dev->otherend); 736 737 err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu", 738 &ring_ref, "event-channel", "%u", &evtchn, NULL); 739 if (err) { 740 xenbus_dev_fatal(dev, err, 741 "reading %s/ring-ref and event-channel", 742 dev->otherend); 743 return err; 744 } 745 746 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; 747 err = xenbus_gather(XBT_NIL, dev->otherend, "protocol", 748 "%63s", protocol, NULL); 749 if (err) 750 strcpy(protocol, "unspecified, assuming native"); 751 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) 752 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; 753 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32)) 754 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32; 755 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64)) 756 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64; 757 else { 758 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); 759 return -1; 760 } 761 err = xenbus_gather(XBT_NIL, dev->otherend, 762 "feature-persistent", "%u", 763 &pers_grants, NULL); 764 if (err) 765 pers_grants = 0; 766 767 be->blkif->vbd.feature_gnt_persistent = pers_grants; 768 be->blkif->vbd.overflow_max_grants = 0; 769 770 pr_info(DRV_PFX "ring-ref %ld, event-channel %d, protocol %d (%s) %s\n", 771 ring_ref, evtchn, be->blkif->blk_protocol, protocol, 772 pers_grants ? "persistent grants" : ""); 773 774 /* Map the shared frame, irq etc. */ 775 err = xen_blkif_map(be->blkif, ring_ref, evtchn); 776 if (err) { 777 xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u", 778 ring_ref, evtchn); 779 return err; 780 } 781 782 return 0; 783 } 784 785 786 /* ** Driver Registration ** */ 787 788 789 static const struct xenbus_device_id xen_blkbk_ids[] = { 790 { "vbd" }, 791 { "" } 792 }; 793 794 795 static DEFINE_XENBUS_DRIVER(xen_blkbk, , 796 .probe = xen_blkbk_probe, 797 .remove = xen_blkbk_remove, 798 .otherend_changed = frontend_changed 799 ); 800 801 802 int xen_blkif_xenbus_init(void) 803 { 804 return xenbus_register_backend(&xen_blkbk_driver); 805 } 806