1 /* Xenbus code for blkif backend 2 Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au> 3 Copyright (C) 2005 XenSource Ltd 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 2 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 */ 16 17 #include <stdarg.h> 18 #include <linux/module.h> 19 #include <linux/kthread.h> 20 #include <xen/events.h> 21 #include <xen/grant_table.h> 22 #include "common.h" 23 24 struct backend_info { 25 struct xenbus_device *dev; 26 struct xen_blkif *blkif; 27 struct xenbus_watch backend_watch; 28 unsigned major; 29 unsigned minor; 30 char *mode; 31 }; 32 33 static struct kmem_cache *xen_blkif_cachep; 34 static void connect(struct backend_info *); 35 static int connect_ring(struct backend_info *); 36 static void backend_changed(struct xenbus_watch *, const char **, 37 unsigned int); 38 39 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be) 40 { 41 return be->dev; 42 } 43 44 static int blkback_name(struct xen_blkif *blkif, char *buf) 45 { 46 char *devpath, *devname; 47 struct xenbus_device *dev = blkif->be->dev; 48 49 devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL); 50 if (IS_ERR(devpath)) 51 return PTR_ERR(devpath); 52 53 devname = strstr(devpath, "/dev/"); 54 if (devname != NULL) 55 devname += strlen("/dev/"); 56 else 57 devname = devpath; 58 59 snprintf(buf, TASK_COMM_LEN, "blkback.%d.%s", blkif->domid, devname); 60 kfree(devpath); 61 62 return 0; 63 } 64 65 static void xen_update_blkif_status(struct xen_blkif *blkif) 66 { 67 int err; 68 char name[TASK_COMM_LEN]; 69 70 /* Not ready to connect? */ 71 if (!blkif->irq || !blkif->vbd.bdev) 72 return; 73 74 /* Already connected? */ 75 if (blkif->be->dev->state == XenbusStateConnected) 76 return; 77 78 /* Attempt to connect: exit if we fail to. */ 79 connect(blkif->be); 80 if (blkif->be->dev->state != XenbusStateConnected) 81 return; 82 83 err = blkback_name(blkif, name); 84 if (err) { 85 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name"); 86 return; 87 } 88 89 err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping); 90 if (err) { 91 xenbus_dev_error(blkif->be->dev, err, "block flush"); 92 return; 93 } 94 invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping); 95 96 blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, name); 97 if (IS_ERR(blkif->xenblkd)) { 98 err = PTR_ERR(blkif->xenblkd); 99 blkif->xenblkd = NULL; 100 xenbus_dev_error(blkif->be->dev, err, "start xenblkd"); 101 } 102 } 103 104 static struct xen_blkif *xen_blkif_alloc(domid_t domid) 105 { 106 struct xen_blkif *blkif; 107 108 blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL); 109 if (!blkif) 110 return ERR_PTR(-ENOMEM); 111 112 blkif->domid = domid; 113 spin_lock_init(&blkif->blk_ring_lock); 114 atomic_set(&blkif->refcnt, 1); 115 init_waitqueue_head(&blkif->wq); 116 init_completion(&blkif->drain_complete); 117 atomic_set(&blkif->drain, 0); 118 blkif->st_print = jiffies; 119 init_waitqueue_head(&blkif->waiting_to_free); 120 121 return blkif; 122 } 123 124 static int xen_blkif_map(struct xen_blkif *blkif, unsigned long shared_page, 125 unsigned int evtchn) 126 { 127 int err; 128 129 /* Already connected through? */ 130 if (blkif->irq) 131 return 0; 132 133 err = xenbus_map_ring_valloc(blkif->be->dev, shared_page, &blkif->blk_ring); 134 if (err < 0) 135 return err; 136 137 switch (blkif->blk_protocol) { 138 case BLKIF_PROTOCOL_NATIVE: 139 { 140 struct blkif_sring *sring; 141 sring = (struct blkif_sring *)blkif->blk_ring; 142 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE); 143 break; 144 } 145 case BLKIF_PROTOCOL_X86_32: 146 { 147 struct blkif_x86_32_sring *sring_x86_32; 148 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring; 149 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE); 150 break; 151 } 152 case BLKIF_PROTOCOL_X86_64: 153 { 154 struct blkif_x86_64_sring *sring_x86_64; 155 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring; 156 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE); 157 break; 158 } 159 default: 160 BUG(); 161 } 162 163 err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn, 164 xen_blkif_be_int, 0, 165 "blkif-backend", blkif); 166 if (err < 0) { 167 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); 168 blkif->blk_rings.common.sring = NULL; 169 return err; 170 } 171 blkif->irq = err; 172 173 return 0; 174 } 175 176 static void xen_blkif_disconnect(struct xen_blkif *blkif) 177 { 178 if (blkif->xenblkd) { 179 kthread_stop(blkif->xenblkd); 180 blkif->xenblkd = NULL; 181 } 182 183 atomic_dec(&blkif->refcnt); 184 wait_event(blkif->waiting_to_free, atomic_read(&blkif->refcnt) == 0); 185 atomic_inc(&blkif->refcnt); 186 187 if (blkif->irq) { 188 unbind_from_irqhandler(blkif->irq, blkif); 189 blkif->irq = 0; 190 } 191 192 if (blkif->blk_rings.common.sring) { 193 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); 194 blkif->blk_rings.common.sring = NULL; 195 } 196 } 197 198 static void xen_blkif_free(struct xen_blkif *blkif) 199 { 200 if (!atomic_dec_and_test(&blkif->refcnt)) 201 BUG(); 202 kmem_cache_free(xen_blkif_cachep, blkif); 203 } 204 205 int __init xen_blkif_interface_init(void) 206 { 207 xen_blkif_cachep = kmem_cache_create("blkif_cache", 208 sizeof(struct xen_blkif), 209 0, 0, NULL); 210 if (!xen_blkif_cachep) 211 return -ENOMEM; 212 213 return 0; 214 } 215 216 /* 217 * sysfs interface for VBD I/O requests 218 */ 219 220 #define VBD_SHOW(name, format, args...) \ 221 static ssize_t show_##name(struct device *_dev, \ 222 struct device_attribute *attr, \ 223 char *buf) \ 224 { \ 225 struct xenbus_device *dev = to_xenbus_device(_dev); \ 226 struct backend_info *be = dev_get_drvdata(&dev->dev); \ 227 \ 228 return sprintf(buf, format, ##args); \ 229 } \ 230 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) 231 232 VBD_SHOW(oo_req, "%d\n", be->blkif->st_oo_req); 233 VBD_SHOW(rd_req, "%d\n", be->blkif->st_rd_req); 234 VBD_SHOW(wr_req, "%d\n", be->blkif->st_wr_req); 235 VBD_SHOW(f_req, "%d\n", be->blkif->st_f_req); 236 VBD_SHOW(ds_req, "%d\n", be->blkif->st_ds_req); 237 VBD_SHOW(rd_sect, "%d\n", be->blkif->st_rd_sect); 238 VBD_SHOW(wr_sect, "%d\n", be->blkif->st_wr_sect); 239 240 static struct attribute *xen_vbdstat_attrs[] = { 241 &dev_attr_oo_req.attr, 242 &dev_attr_rd_req.attr, 243 &dev_attr_wr_req.attr, 244 &dev_attr_f_req.attr, 245 &dev_attr_ds_req.attr, 246 &dev_attr_rd_sect.attr, 247 &dev_attr_wr_sect.attr, 248 NULL 249 }; 250 251 static struct attribute_group xen_vbdstat_group = { 252 .name = "statistics", 253 .attrs = xen_vbdstat_attrs, 254 }; 255 256 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor); 257 VBD_SHOW(mode, "%s\n", be->mode); 258 259 static int xenvbd_sysfs_addif(struct xenbus_device *dev) 260 { 261 int error; 262 263 error = device_create_file(&dev->dev, &dev_attr_physical_device); 264 if (error) 265 goto fail1; 266 267 error = device_create_file(&dev->dev, &dev_attr_mode); 268 if (error) 269 goto fail2; 270 271 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group); 272 if (error) 273 goto fail3; 274 275 return 0; 276 277 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 278 fail2: device_remove_file(&dev->dev, &dev_attr_mode); 279 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device); 280 return error; 281 } 282 283 static void xenvbd_sysfs_delif(struct xenbus_device *dev) 284 { 285 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 286 device_remove_file(&dev->dev, &dev_attr_mode); 287 device_remove_file(&dev->dev, &dev_attr_physical_device); 288 } 289 290 291 static void xen_vbd_free(struct xen_vbd *vbd) 292 { 293 if (vbd->bdev) 294 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE); 295 vbd->bdev = NULL; 296 } 297 298 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, 299 unsigned major, unsigned minor, int readonly, 300 int cdrom) 301 { 302 struct xen_vbd *vbd; 303 struct block_device *bdev; 304 struct request_queue *q; 305 306 vbd = &blkif->vbd; 307 vbd->handle = handle; 308 vbd->readonly = readonly; 309 vbd->type = 0; 310 311 vbd->pdevice = MKDEV(major, minor); 312 313 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ? 314 FMODE_READ : FMODE_WRITE, NULL); 315 316 if (IS_ERR(bdev)) { 317 DPRINTK("xen_vbd_create: device %08x could not be opened.\n", 318 vbd->pdevice); 319 return -ENOENT; 320 } 321 322 vbd->bdev = bdev; 323 if (vbd->bdev->bd_disk == NULL) { 324 DPRINTK("xen_vbd_create: device %08x doesn't exist.\n", 325 vbd->pdevice); 326 xen_vbd_free(vbd); 327 return -ENOENT; 328 } 329 vbd->size = vbd_sz(vbd); 330 331 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom) 332 vbd->type |= VDISK_CDROM; 333 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE) 334 vbd->type |= VDISK_REMOVABLE; 335 336 q = bdev_get_queue(bdev); 337 if (q && q->flush_flags) 338 vbd->flush_support = true; 339 340 if (q && blk_queue_secdiscard(q)) 341 vbd->discard_secure = true; 342 343 DPRINTK("Successful creation of handle=%04x (dom=%u)\n", 344 handle, blkif->domid); 345 return 0; 346 } 347 static int xen_blkbk_remove(struct xenbus_device *dev) 348 { 349 struct backend_info *be = dev_get_drvdata(&dev->dev); 350 351 DPRINTK(""); 352 353 if (be->major || be->minor) 354 xenvbd_sysfs_delif(dev); 355 356 if (be->backend_watch.node) { 357 unregister_xenbus_watch(&be->backend_watch); 358 kfree(be->backend_watch.node); 359 be->backend_watch.node = NULL; 360 } 361 362 if (be->blkif) { 363 xen_blkif_disconnect(be->blkif); 364 xen_vbd_free(&be->blkif->vbd); 365 xen_blkif_free(be->blkif); 366 be->blkif = NULL; 367 } 368 369 kfree(be); 370 dev_set_drvdata(&dev->dev, NULL); 371 return 0; 372 } 373 374 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt, 375 struct backend_info *be, int state) 376 { 377 struct xenbus_device *dev = be->dev; 378 int err; 379 380 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache", 381 "%d", state); 382 if (err) 383 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err); 384 385 return err; 386 } 387 388 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be) 389 { 390 struct xenbus_device *dev = be->dev; 391 struct xen_blkif *blkif = be->blkif; 392 int err; 393 int state = 0; 394 struct block_device *bdev = be->blkif->vbd.bdev; 395 struct request_queue *q = bdev_get_queue(bdev); 396 397 if (blk_queue_discard(q)) { 398 err = xenbus_printf(xbt, dev->nodename, 399 "discard-granularity", "%u", 400 q->limits.discard_granularity); 401 if (err) { 402 dev_warn(&dev->dev, "writing discard-granularity (%d)", err); 403 return; 404 } 405 err = xenbus_printf(xbt, dev->nodename, 406 "discard-alignment", "%u", 407 q->limits.discard_alignment); 408 if (err) { 409 dev_warn(&dev->dev, "writing discard-alignment (%d)", err); 410 return; 411 } 412 state = 1; 413 /* Optional. */ 414 err = xenbus_printf(xbt, dev->nodename, 415 "discard-secure", "%d", 416 blkif->vbd.discard_secure); 417 if (err) { 418 dev_warn(&dev->dev, "writing discard-secure (%d)", err); 419 return; 420 } 421 } 422 err = xenbus_printf(xbt, dev->nodename, "feature-discard", 423 "%d", state); 424 if (err) 425 dev_warn(&dev->dev, "writing feature-discard (%d)", err); 426 } 427 int xen_blkbk_barrier(struct xenbus_transaction xbt, 428 struct backend_info *be, int state) 429 { 430 struct xenbus_device *dev = be->dev; 431 int err; 432 433 err = xenbus_printf(xbt, dev->nodename, "feature-barrier", 434 "%d", state); 435 if (err) 436 dev_warn(&dev->dev, "writing feature-barrier (%d)", err); 437 438 return err; 439 } 440 441 /* 442 * Entry point to this code when a new device is created. Allocate the basic 443 * structures, and watch the store waiting for the hotplug scripts to tell us 444 * the device's physical major and minor numbers. Switch to InitWait. 445 */ 446 static int xen_blkbk_probe(struct xenbus_device *dev, 447 const struct xenbus_device_id *id) 448 { 449 int err; 450 struct backend_info *be = kzalloc(sizeof(struct backend_info), 451 GFP_KERNEL); 452 if (!be) { 453 xenbus_dev_fatal(dev, -ENOMEM, 454 "allocating backend structure"); 455 return -ENOMEM; 456 } 457 be->dev = dev; 458 dev_set_drvdata(&dev->dev, be); 459 460 be->blkif = xen_blkif_alloc(dev->otherend_id); 461 if (IS_ERR(be->blkif)) { 462 err = PTR_ERR(be->blkif); 463 be->blkif = NULL; 464 xenbus_dev_fatal(dev, err, "creating block interface"); 465 goto fail; 466 } 467 468 /* setup back pointer */ 469 be->blkif->be = be; 470 471 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed, 472 "%s/%s", dev->nodename, "physical-device"); 473 if (err) 474 goto fail; 475 476 err = xenbus_switch_state(dev, XenbusStateInitWait); 477 if (err) 478 goto fail; 479 480 return 0; 481 482 fail: 483 DPRINTK("failed"); 484 xen_blkbk_remove(dev); 485 return err; 486 } 487 488 489 /* 490 * Callback received when the hotplug scripts have placed the physical-device 491 * node. Read it and the mode node, and create a vbd. If the frontend is 492 * ready, connect. 493 */ 494 static void backend_changed(struct xenbus_watch *watch, 495 const char **vec, unsigned int len) 496 { 497 int err; 498 unsigned major; 499 unsigned minor; 500 struct backend_info *be 501 = container_of(watch, struct backend_info, backend_watch); 502 struct xenbus_device *dev = be->dev; 503 int cdrom = 0; 504 char *device_type; 505 506 DPRINTK(""); 507 508 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x", 509 &major, &minor); 510 if (XENBUS_EXIST_ERR(err)) { 511 /* 512 * Since this watch will fire once immediately after it is 513 * registered, we expect this. Ignore it, and wait for the 514 * hotplug scripts. 515 */ 516 return; 517 } 518 if (err != 2) { 519 xenbus_dev_fatal(dev, err, "reading physical-device"); 520 return; 521 } 522 523 if ((be->major || be->minor) && 524 ((be->major != major) || (be->minor != minor))) { 525 pr_warn(DRV_PFX "changing physical device (from %x:%x to %x:%x) not supported.\n", 526 be->major, be->minor, major, minor); 527 return; 528 } 529 530 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL); 531 if (IS_ERR(be->mode)) { 532 err = PTR_ERR(be->mode); 533 be->mode = NULL; 534 xenbus_dev_fatal(dev, err, "reading mode"); 535 return; 536 } 537 538 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL); 539 if (!IS_ERR(device_type)) { 540 cdrom = strcmp(device_type, "cdrom") == 0; 541 kfree(device_type); 542 } 543 544 if (be->major == 0 && be->minor == 0) { 545 /* Front end dir is a number, which is used as the handle. */ 546 547 char *p = strrchr(dev->otherend, '/') + 1; 548 long handle; 549 err = strict_strtoul(p, 0, &handle); 550 if (err) 551 return; 552 553 be->major = major; 554 be->minor = minor; 555 556 err = xen_vbd_create(be->blkif, handle, major, minor, 557 (NULL == strchr(be->mode, 'w')), cdrom); 558 if (err) { 559 be->major = 0; 560 be->minor = 0; 561 xenbus_dev_fatal(dev, err, "creating vbd structure"); 562 return; 563 } 564 565 err = xenvbd_sysfs_addif(dev); 566 if (err) { 567 xen_vbd_free(&be->blkif->vbd); 568 be->major = 0; 569 be->minor = 0; 570 xenbus_dev_fatal(dev, err, "creating sysfs entries"); 571 return; 572 } 573 574 /* We're potentially connected now */ 575 xen_update_blkif_status(be->blkif); 576 } 577 } 578 579 580 /* 581 * Callback received when the frontend's state changes. 582 */ 583 static void frontend_changed(struct xenbus_device *dev, 584 enum xenbus_state frontend_state) 585 { 586 struct backend_info *be = dev_get_drvdata(&dev->dev); 587 int err; 588 589 DPRINTK("%s", xenbus_strstate(frontend_state)); 590 591 switch (frontend_state) { 592 case XenbusStateInitialising: 593 if (dev->state == XenbusStateClosed) { 594 pr_info(DRV_PFX "%s: prepare for reconnect\n", 595 dev->nodename); 596 xenbus_switch_state(dev, XenbusStateInitWait); 597 } 598 break; 599 600 case XenbusStateInitialised: 601 case XenbusStateConnected: 602 /* 603 * Ensure we connect even when two watches fire in 604 * close succession and we miss the intermediate value 605 * of frontend_state. 606 */ 607 if (dev->state == XenbusStateConnected) 608 break; 609 610 /* 611 * Enforce precondition before potential leak point. 612 * xen_blkif_disconnect() is idempotent. 613 */ 614 xen_blkif_disconnect(be->blkif); 615 616 err = connect_ring(be); 617 if (err) 618 break; 619 xen_update_blkif_status(be->blkif); 620 break; 621 622 case XenbusStateClosing: 623 xenbus_switch_state(dev, XenbusStateClosing); 624 break; 625 626 case XenbusStateClosed: 627 xen_blkif_disconnect(be->blkif); 628 xenbus_switch_state(dev, XenbusStateClosed); 629 if (xenbus_dev_is_online(dev)) 630 break; 631 /* fall through if not online */ 632 case XenbusStateUnknown: 633 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */ 634 device_unregister(&dev->dev); 635 break; 636 637 default: 638 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", 639 frontend_state); 640 break; 641 } 642 } 643 644 645 /* ** Connection ** */ 646 647 648 /* 649 * Write the physical details regarding the block device to the store, and 650 * switch to Connected state. 651 */ 652 static void connect(struct backend_info *be) 653 { 654 struct xenbus_transaction xbt; 655 int err; 656 struct xenbus_device *dev = be->dev; 657 658 DPRINTK("%s", dev->otherend); 659 660 /* Supply the information about the device the frontend needs */ 661 again: 662 err = xenbus_transaction_start(&xbt); 663 if (err) { 664 xenbus_dev_fatal(dev, err, "starting transaction"); 665 return; 666 } 667 668 /* If we can't advertise it is OK. */ 669 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support); 670 671 xen_blkbk_discard(xbt, be); 672 673 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); 674 675 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 676 (unsigned long long)vbd_sz(&be->blkif->vbd)); 677 if (err) { 678 xenbus_dev_fatal(dev, err, "writing %s/sectors", 679 dev->nodename); 680 goto abort; 681 } 682 683 /* FIXME: use a typename instead */ 684 err = xenbus_printf(xbt, dev->nodename, "info", "%u", 685 be->blkif->vbd.type | 686 (be->blkif->vbd.readonly ? VDISK_READONLY : 0)); 687 if (err) { 688 xenbus_dev_fatal(dev, err, "writing %s/info", 689 dev->nodename); 690 goto abort; 691 } 692 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu", 693 (unsigned long) 694 bdev_logical_block_size(be->blkif->vbd.bdev)); 695 if (err) { 696 xenbus_dev_fatal(dev, err, "writing %s/sector-size", 697 dev->nodename); 698 goto abort; 699 } 700 701 err = xenbus_transaction_end(xbt, 0); 702 if (err == -EAGAIN) 703 goto again; 704 if (err) 705 xenbus_dev_fatal(dev, err, "ending transaction"); 706 707 err = xenbus_switch_state(dev, XenbusStateConnected); 708 if (err) 709 xenbus_dev_fatal(dev, err, "%s: switching to Connected state", 710 dev->nodename); 711 712 return; 713 abort: 714 xenbus_transaction_end(xbt, 1); 715 } 716 717 718 static int connect_ring(struct backend_info *be) 719 { 720 struct xenbus_device *dev = be->dev; 721 unsigned long ring_ref; 722 unsigned int evtchn; 723 char protocol[64] = ""; 724 int err; 725 726 DPRINTK("%s", dev->otherend); 727 728 err = xenbus_gather(XBT_NIL, dev->otherend, "ring-ref", "%lu", 729 &ring_ref, "event-channel", "%u", &evtchn, NULL); 730 if (err) { 731 xenbus_dev_fatal(dev, err, 732 "reading %s/ring-ref and event-channel", 733 dev->otherend); 734 return err; 735 } 736 737 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; 738 err = xenbus_gather(XBT_NIL, dev->otherend, "protocol", 739 "%63s", protocol, NULL); 740 if (err) 741 strcpy(protocol, "unspecified, assuming native"); 742 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) 743 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; 744 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32)) 745 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32; 746 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64)) 747 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64; 748 else { 749 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); 750 return -1; 751 } 752 pr_info(DRV_PFX "ring-ref %ld, event-channel %d, protocol %d (%s)\n", 753 ring_ref, evtchn, be->blkif->blk_protocol, protocol); 754 755 /* Map the shared frame, irq etc. */ 756 err = xen_blkif_map(be->blkif, ring_ref, evtchn); 757 if (err) { 758 xenbus_dev_fatal(dev, err, "mapping ring-ref %lu port %u", 759 ring_ref, evtchn); 760 return err; 761 } 762 763 return 0; 764 } 765 766 767 /* ** Driver Registration ** */ 768 769 770 static const struct xenbus_device_id xen_blkbk_ids[] = { 771 { "vbd" }, 772 { "" } 773 }; 774 775 776 static DEFINE_XENBUS_DRIVER(xen_blkbk, , 777 .probe = xen_blkbk_probe, 778 .remove = xen_blkbk_remove, 779 .otherend_changed = frontend_changed 780 ); 781 782 783 int xen_blkif_xenbus_init(void) 784 { 785 return xenbus_register_backend(&xen_blkbk_driver); 786 } 787