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 /* On the XenBus the max length of 'ring-ref%u'. */ 27 #define RINGREF_NAME_LEN (20) 28 29 struct backend_info { 30 struct xenbus_device *dev; 31 struct xen_blkif *blkif; 32 struct xenbus_watch backend_watch; 33 unsigned major; 34 unsigned minor; 35 char *mode; 36 }; 37 38 static struct kmem_cache *xen_blkif_cachep; 39 static void connect(struct backend_info *); 40 static int connect_ring(struct backend_info *); 41 static void backend_changed(struct xenbus_watch *, const char *, 42 const char *); 43 static void xen_blkif_free(struct xen_blkif *blkif); 44 static void xen_vbd_free(struct xen_vbd *vbd); 45 46 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be) 47 { 48 return be->dev; 49 } 50 51 /* 52 * The last request could free the device from softirq context and 53 * xen_blkif_free() can sleep. 54 */ 55 static void xen_blkif_deferred_free(struct work_struct *work) 56 { 57 struct xen_blkif *blkif; 58 59 blkif = container_of(work, struct xen_blkif, free_work); 60 xen_blkif_free(blkif); 61 } 62 63 static int blkback_name(struct xen_blkif *blkif, char *buf) 64 { 65 char *devpath, *devname; 66 struct xenbus_device *dev = blkif->be->dev; 67 68 devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL); 69 if (IS_ERR(devpath)) 70 return PTR_ERR(devpath); 71 72 devname = strstr(devpath, "/dev/"); 73 if (devname != NULL) 74 devname += strlen("/dev/"); 75 else 76 devname = devpath; 77 78 snprintf(buf, TASK_COMM_LEN, "%d.%s", blkif->domid, devname); 79 kfree(devpath); 80 81 return 0; 82 } 83 84 static void xen_update_blkif_status(struct xen_blkif *blkif) 85 { 86 int err; 87 char name[TASK_COMM_LEN]; 88 struct xen_blkif_ring *ring; 89 int i; 90 91 /* Not ready to connect? */ 92 if (!blkif->rings || !blkif->rings[0].irq || !blkif->vbd.bdev) 93 return; 94 95 /* Already connected? */ 96 if (blkif->be->dev->state == XenbusStateConnected) 97 return; 98 99 /* Attempt to connect: exit if we fail to. */ 100 connect(blkif->be); 101 if (blkif->be->dev->state != XenbusStateConnected) 102 return; 103 104 err = blkback_name(blkif, name); 105 if (err) { 106 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name"); 107 return; 108 } 109 110 err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping); 111 if (err) { 112 xenbus_dev_error(blkif->be->dev, err, "block flush"); 113 return; 114 } 115 invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping); 116 117 for (i = 0; i < blkif->nr_rings; i++) { 118 ring = &blkif->rings[i]; 119 ring->xenblkd = kthread_run(xen_blkif_schedule, ring, "%s-%d", name, i); 120 if (IS_ERR(ring->xenblkd)) { 121 err = PTR_ERR(ring->xenblkd); 122 ring->xenblkd = NULL; 123 xenbus_dev_fatal(blkif->be->dev, err, 124 "start %s-%d xenblkd", name, i); 125 goto out; 126 } 127 } 128 return; 129 130 out: 131 while (--i >= 0) { 132 ring = &blkif->rings[i]; 133 kthread_stop(ring->xenblkd); 134 } 135 return; 136 } 137 138 static int xen_blkif_alloc_rings(struct xen_blkif *blkif) 139 { 140 unsigned int r; 141 142 blkif->rings = kzalloc(blkif->nr_rings * sizeof(struct xen_blkif_ring), GFP_KERNEL); 143 if (!blkif->rings) 144 return -ENOMEM; 145 146 for (r = 0; r < blkif->nr_rings; r++) { 147 struct xen_blkif_ring *ring = &blkif->rings[r]; 148 149 spin_lock_init(&ring->blk_ring_lock); 150 init_waitqueue_head(&ring->wq); 151 INIT_LIST_HEAD(&ring->pending_free); 152 INIT_LIST_HEAD(&ring->persistent_purge_list); 153 INIT_WORK(&ring->persistent_purge_work, xen_blkbk_unmap_purged_grants); 154 spin_lock_init(&ring->free_pages_lock); 155 INIT_LIST_HEAD(&ring->free_pages); 156 157 spin_lock_init(&ring->pending_free_lock); 158 init_waitqueue_head(&ring->pending_free_wq); 159 init_waitqueue_head(&ring->shutdown_wq); 160 ring->blkif = blkif; 161 ring->st_print = jiffies; 162 ring->active = true; 163 } 164 165 return 0; 166 } 167 168 static struct xen_blkif *xen_blkif_alloc(domid_t domid) 169 { 170 struct xen_blkif *blkif; 171 172 BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST); 173 174 blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL); 175 if (!blkif) 176 return ERR_PTR(-ENOMEM); 177 178 blkif->domid = domid; 179 atomic_set(&blkif->refcnt, 1); 180 init_completion(&blkif->drain_complete); 181 INIT_WORK(&blkif->free_work, xen_blkif_deferred_free); 182 183 return blkif; 184 } 185 186 static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref, 187 unsigned int nr_grefs, unsigned int evtchn) 188 { 189 int err; 190 struct xen_blkif *blkif = ring->blkif; 191 192 /* Already connected through? */ 193 if (ring->irq) 194 return 0; 195 196 err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs, 197 &ring->blk_ring); 198 if (err < 0) 199 return err; 200 201 switch (blkif->blk_protocol) { 202 case BLKIF_PROTOCOL_NATIVE: 203 { 204 struct blkif_sring *sring; 205 sring = (struct blkif_sring *)ring->blk_ring; 206 BACK_RING_INIT(&ring->blk_rings.native, sring, 207 XEN_PAGE_SIZE * nr_grefs); 208 break; 209 } 210 case BLKIF_PROTOCOL_X86_32: 211 { 212 struct blkif_x86_32_sring *sring_x86_32; 213 sring_x86_32 = (struct blkif_x86_32_sring *)ring->blk_ring; 214 BACK_RING_INIT(&ring->blk_rings.x86_32, sring_x86_32, 215 XEN_PAGE_SIZE * nr_grefs); 216 break; 217 } 218 case BLKIF_PROTOCOL_X86_64: 219 { 220 struct blkif_x86_64_sring *sring_x86_64; 221 sring_x86_64 = (struct blkif_x86_64_sring *)ring->blk_ring; 222 BACK_RING_INIT(&ring->blk_rings.x86_64, sring_x86_64, 223 XEN_PAGE_SIZE * nr_grefs); 224 break; 225 } 226 default: 227 BUG(); 228 } 229 230 err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn, 231 xen_blkif_be_int, 0, 232 "blkif-backend", ring); 233 if (err < 0) { 234 xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring); 235 ring->blk_rings.common.sring = NULL; 236 return err; 237 } 238 ring->irq = err; 239 240 return 0; 241 } 242 243 static int xen_blkif_disconnect(struct xen_blkif *blkif) 244 { 245 struct pending_req *req, *n; 246 unsigned int j, r; 247 bool busy = false; 248 249 for (r = 0; r < blkif->nr_rings; r++) { 250 struct xen_blkif_ring *ring = &blkif->rings[r]; 251 unsigned int i = 0; 252 253 if (!ring->active) 254 continue; 255 256 if (ring->xenblkd) { 257 kthread_stop(ring->xenblkd); 258 wake_up(&ring->shutdown_wq); 259 } 260 261 /* The above kthread_stop() guarantees that at this point we 262 * don't have any discard_io or other_io requests. So, checking 263 * for inflight IO is enough. 264 */ 265 if (atomic_read(&ring->inflight) > 0) { 266 busy = true; 267 continue; 268 } 269 270 if (ring->irq) { 271 unbind_from_irqhandler(ring->irq, ring); 272 ring->irq = 0; 273 } 274 275 if (ring->blk_rings.common.sring) { 276 xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring); 277 ring->blk_rings.common.sring = NULL; 278 } 279 280 /* Remove all persistent grants and the cache of ballooned pages. */ 281 xen_blkbk_free_caches(ring); 282 283 /* Check that there is no request in use */ 284 list_for_each_entry_safe(req, n, &ring->pending_free, free_list) { 285 list_del(&req->free_list); 286 287 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) 288 kfree(req->segments[j]); 289 290 for (j = 0; j < MAX_INDIRECT_PAGES; j++) 291 kfree(req->indirect_pages[j]); 292 293 kfree(req); 294 i++; 295 } 296 297 BUG_ON(atomic_read(&ring->persistent_gnt_in_use) != 0); 298 BUG_ON(!list_empty(&ring->persistent_purge_list)); 299 BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts)); 300 BUG_ON(!list_empty(&ring->free_pages)); 301 BUG_ON(ring->free_pages_num != 0); 302 BUG_ON(ring->persistent_gnt_c != 0); 303 WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages)); 304 ring->active = false; 305 } 306 if (busy) 307 return -EBUSY; 308 309 blkif->nr_ring_pages = 0; 310 /* 311 * blkif->rings was allocated in connect_ring, so we should free it in 312 * here. 313 */ 314 kfree(blkif->rings); 315 blkif->rings = NULL; 316 blkif->nr_rings = 0; 317 318 return 0; 319 } 320 321 static void xen_blkif_free(struct xen_blkif *blkif) 322 { 323 WARN_ON(xen_blkif_disconnect(blkif)); 324 xen_vbd_free(&blkif->vbd); 325 kfree(blkif->be->mode); 326 kfree(blkif->be); 327 328 /* Make sure everything is drained before shutting down */ 329 kmem_cache_free(xen_blkif_cachep, blkif); 330 } 331 332 int __init xen_blkif_interface_init(void) 333 { 334 xen_blkif_cachep = kmem_cache_create("blkif_cache", 335 sizeof(struct xen_blkif), 336 0, 0, NULL); 337 if (!xen_blkif_cachep) 338 return -ENOMEM; 339 340 return 0; 341 } 342 343 /* 344 * sysfs interface for VBD I/O requests 345 */ 346 347 #define VBD_SHOW_ALLRING(name, format) \ 348 static ssize_t show_##name(struct device *_dev, \ 349 struct device_attribute *attr, \ 350 char *buf) \ 351 { \ 352 struct xenbus_device *dev = to_xenbus_device(_dev); \ 353 struct backend_info *be = dev_get_drvdata(&dev->dev); \ 354 struct xen_blkif *blkif = be->blkif; \ 355 unsigned int i; \ 356 unsigned long long result = 0; \ 357 \ 358 if (!blkif->rings) \ 359 goto out; \ 360 \ 361 for (i = 0; i < blkif->nr_rings; i++) { \ 362 struct xen_blkif_ring *ring = &blkif->rings[i]; \ 363 \ 364 result += ring->st_##name; \ 365 } \ 366 \ 367 out: \ 368 return sprintf(buf, format, result); \ 369 } \ 370 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) 371 372 VBD_SHOW_ALLRING(oo_req, "%llu\n"); 373 VBD_SHOW_ALLRING(rd_req, "%llu\n"); 374 VBD_SHOW_ALLRING(wr_req, "%llu\n"); 375 VBD_SHOW_ALLRING(f_req, "%llu\n"); 376 VBD_SHOW_ALLRING(ds_req, "%llu\n"); 377 VBD_SHOW_ALLRING(rd_sect, "%llu\n"); 378 VBD_SHOW_ALLRING(wr_sect, "%llu\n"); 379 380 static struct attribute *xen_vbdstat_attrs[] = { 381 &dev_attr_oo_req.attr, 382 &dev_attr_rd_req.attr, 383 &dev_attr_wr_req.attr, 384 &dev_attr_f_req.attr, 385 &dev_attr_ds_req.attr, 386 &dev_attr_rd_sect.attr, 387 &dev_attr_wr_sect.attr, 388 NULL 389 }; 390 391 static const struct attribute_group xen_vbdstat_group = { 392 .name = "statistics", 393 .attrs = xen_vbdstat_attrs, 394 }; 395 396 #define VBD_SHOW(name, format, args...) \ 397 static ssize_t show_##name(struct device *_dev, \ 398 struct device_attribute *attr, \ 399 char *buf) \ 400 { \ 401 struct xenbus_device *dev = to_xenbus_device(_dev); \ 402 struct backend_info *be = dev_get_drvdata(&dev->dev); \ 403 \ 404 return sprintf(buf, format, ##args); \ 405 } \ 406 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) 407 408 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor); 409 VBD_SHOW(mode, "%s\n", be->mode); 410 411 static int xenvbd_sysfs_addif(struct xenbus_device *dev) 412 { 413 int error; 414 415 error = device_create_file(&dev->dev, &dev_attr_physical_device); 416 if (error) 417 goto fail1; 418 419 error = device_create_file(&dev->dev, &dev_attr_mode); 420 if (error) 421 goto fail2; 422 423 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group); 424 if (error) 425 goto fail3; 426 427 return 0; 428 429 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 430 fail2: device_remove_file(&dev->dev, &dev_attr_mode); 431 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device); 432 return error; 433 } 434 435 static void xenvbd_sysfs_delif(struct xenbus_device *dev) 436 { 437 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 438 device_remove_file(&dev->dev, &dev_attr_mode); 439 device_remove_file(&dev->dev, &dev_attr_physical_device); 440 } 441 442 443 static void xen_vbd_free(struct xen_vbd *vbd) 444 { 445 if (vbd->bdev) 446 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE); 447 vbd->bdev = NULL; 448 } 449 450 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, 451 unsigned major, unsigned minor, int readonly, 452 int cdrom) 453 { 454 struct xen_vbd *vbd; 455 struct block_device *bdev; 456 struct request_queue *q; 457 458 vbd = &blkif->vbd; 459 vbd->handle = handle; 460 vbd->readonly = readonly; 461 vbd->type = 0; 462 463 vbd->pdevice = MKDEV(major, minor); 464 465 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ? 466 FMODE_READ : FMODE_WRITE, NULL); 467 468 if (IS_ERR(bdev)) { 469 pr_warn("xen_vbd_create: device %08x could not be opened\n", 470 vbd->pdevice); 471 return -ENOENT; 472 } 473 474 vbd->bdev = bdev; 475 if (vbd->bdev->bd_disk == NULL) { 476 pr_warn("xen_vbd_create: device %08x doesn't exist\n", 477 vbd->pdevice); 478 xen_vbd_free(vbd); 479 return -ENOENT; 480 } 481 vbd->size = vbd_sz(vbd); 482 483 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom) 484 vbd->type |= VDISK_CDROM; 485 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE) 486 vbd->type |= VDISK_REMOVABLE; 487 488 q = bdev_get_queue(bdev); 489 if (q && test_bit(QUEUE_FLAG_WC, &q->queue_flags)) 490 vbd->flush_support = true; 491 492 if (q && blk_queue_secure_erase(q)) 493 vbd->discard_secure = true; 494 495 pr_debug("Successful creation of handle=%04x (dom=%u)\n", 496 handle, blkif->domid); 497 return 0; 498 } 499 static int xen_blkbk_remove(struct xenbus_device *dev) 500 { 501 struct backend_info *be = dev_get_drvdata(&dev->dev); 502 503 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 504 505 if (be->major || be->minor) 506 xenvbd_sysfs_delif(dev); 507 508 if (be->backend_watch.node) { 509 unregister_xenbus_watch(&be->backend_watch); 510 kfree(be->backend_watch.node); 511 be->backend_watch.node = NULL; 512 } 513 514 dev_set_drvdata(&dev->dev, NULL); 515 516 if (be->blkif) { 517 xen_blkif_disconnect(be->blkif); 518 519 /* Put the reference we set in xen_blkif_alloc(). */ 520 xen_blkif_put(be->blkif); 521 } 522 523 return 0; 524 } 525 526 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt, 527 struct backend_info *be, int state) 528 { 529 struct xenbus_device *dev = be->dev; 530 int err; 531 532 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache", 533 "%d", state); 534 if (err) 535 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err); 536 537 return err; 538 } 539 540 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be) 541 { 542 struct xenbus_device *dev = be->dev; 543 struct xen_blkif *blkif = be->blkif; 544 int err; 545 int state = 0; 546 struct block_device *bdev = be->blkif->vbd.bdev; 547 struct request_queue *q = bdev_get_queue(bdev); 548 549 if (!xenbus_read_unsigned(dev->nodename, "discard-enable", 1)) 550 return; 551 552 if (blk_queue_discard(q)) { 553 err = xenbus_printf(xbt, dev->nodename, 554 "discard-granularity", "%u", 555 q->limits.discard_granularity); 556 if (err) { 557 dev_warn(&dev->dev, "writing discard-granularity (%d)", err); 558 return; 559 } 560 err = xenbus_printf(xbt, dev->nodename, 561 "discard-alignment", "%u", 562 q->limits.discard_alignment); 563 if (err) { 564 dev_warn(&dev->dev, "writing discard-alignment (%d)", err); 565 return; 566 } 567 state = 1; 568 /* Optional. */ 569 err = xenbus_printf(xbt, dev->nodename, 570 "discard-secure", "%d", 571 blkif->vbd.discard_secure); 572 if (err) { 573 dev_warn(&dev->dev, "writing discard-secure (%d)", err); 574 return; 575 } 576 } 577 err = xenbus_printf(xbt, dev->nodename, "feature-discard", 578 "%d", state); 579 if (err) 580 dev_warn(&dev->dev, "writing feature-discard (%d)", err); 581 } 582 int xen_blkbk_barrier(struct xenbus_transaction xbt, 583 struct backend_info *be, int state) 584 { 585 struct xenbus_device *dev = be->dev; 586 int err; 587 588 err = xenbus_printf(xbt, dev->nodename, "feature-barrier", 589 "%d", state); 590 if (err) 591 dev_warn(&dev->dev, "writing feature-barrier (%d)", err); 592 593 return err; 594 } 595 596 /* 597 * Entry point to this code when a new device is created. Allocate the basic 598 * structures, and watch the store waiting for the hotplug scripts to tell us 599 * the device's physical major and minor numbers. Switch to InitWait. 600 */ 601 static int xen_blkbk_probe(struct xenbus_device *dev, 602 const struct xenbus_device_id *id) 603 { 604 int err; 605 struct backend_info *be = kzalloc(sizeof(struct backend_info), 606 GFP_KERNEL); 607 608 /* match the pr_debug in xen_blkbk_remove */ 609 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 610 611 if (!be) { 612 xenbus_dev_fatal(dev, -ENOMEM, 613 "allocating backend structure"); 614 return -ENOMEM; 615 } 616 be->dev = dev; 617 dev_set_drvdata(&dev->dev, be); 618 619 be->blkif = xen_blkif_alloc(dev->otherend_id); 620 if (IS_ERR(be->blkif)) { 621 err = PTR_ERR(be->blkif); 622 be->blkif = NULL; 623 xenbus_dev_fatal(dev, err, "creating block interface"); 624 goto fail; 625 } 626 627 err = xenbus_printf(XBT_NIL, dev->nodename, 628 "feature-max-indirect-segments", "%u", 629 MAX_INDIRECT_SEGMENTS); 630 if (err) 631 dev_warn(&dev->dev, 632 "writing %s/feature-max-indirect-segments (%d)", 633 dev->nodename, err); 634 635 /* Multi-queue: advertise how many queues are supported by us.*/ 636 err = xenbus_printf(XBT_NIL, dev->nodename, 637 "multi-queue-max-queues", "%u", xenblk_max_queues); 638 if (err) 639 pr_warn("Error writing multi-queue-max-queues\n"); 640 641 /* setup back pointer */ 642 be->blkif->be = be; 643 644 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed, 645 "%s/%s", dev->nodename, "physical-device"); 646 if (err) 647 goto fail; 648 649 err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u", 650 xen_blkif_max_ring_order); 651 if (err) 652 pr_warn("%s write out 'max-ring-page-order' failed\n", __func__); 653 654 err = xenbus_switch_state(dev, XenbusStateInitWait); 655 if (err) 656 goto fail; 657 658 return 0; 659 660 fail: 661 pr_warn("%s failed\n", __func__); 662 xen_blkbk_remove(dev); 663 return err; 664 } 665 666 667 /* 668 * Callback received when the hotplug scripts have placed the physical-device 669 * node. Read it and the mode node, and create a vbd. If the frontend is 670 * ready, connect. 671 */ 672 static void backend_changed(struct xenbus_watch *watch, 673 const char *path, const char *token) 674 { 675 int err; 676 unsigned major; 677 unsigned minor; 678 struct backend_info *be 679 = container_of(watch, struct backend_info, backend_watch); 680 struct xenbus_device *dev = be->dev; 681 int cdrom = 0; 682 unsigned long handle; 683 char *device_type; 684 685 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 686 687 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x", 688 &major, &minor); 689 if (XENBUS_EXIST_ERR(err)) { 690 /* 691 * Since this watch will fire once immediately after it is 692 * registered, we expect this. Ignore it, and wait for the 693 * hotplug scripts. 694 */ 695 return; 696 } 697 if (err != 2) { 698 xenbus_dev_fatal(dev, err, "reading physical-device"); 699 return; 700 } 701 702 if (be->major | be->minor) { 703 if (be->major != major || be->minor != minor) 704 pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n", 705 be->major, be->minor, major, minor); 706 return; 707 } 708 709 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL); 710 if (IS_ERR(be->mode)) { 711 err = PTR_ERR(be->mode); 712 be->mode = NULL; 713 xenbus_dev_fatal(dev, err, "reading mode"); 714 return; 715 } 716 717 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL); 718 if (!IS_ERR(device_type)) { 719 cdrom = strcmp(device_type, "cdrom") == 0; 720 kfree(device_type); 721 } 722 723 /* Front end dir is a number, which is used as the handle. */ 724 err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle); 725 if (err) { 726 kfree(be->mode); 727 be->mode = NULL; 728 return; 729 } 730 731 be->major = major; 732 be->minor = minor; 733 734 err = xen_vbd_create(be->blkif, handle, major, minor, 735 !strchr(be->mode, 'w'), cdrom); 736 737 if (err) 738 xenbus_dev_fatal(dev, err, "creating vbd structure"); 739 else { 740 err = xenvbd_sysfs_addif(dev); 741 if (err) { 742 xen_vbd_free(&be->blkif->vbd); 743 xenbus_dev_fatal(dev, err, "creating sysfs entries"); 744 } 745 } 746 747 if (err) { 748 kfree(be->mode); 749 be->mode = NULL; 750 be->major = 0; 751 be->minor = 0; 752 } else { 753 /* We're potentially connected now */ 754 xen_update_blkif_status(be->blkif); 755 } 756 } 757 758 759 /* 760 * Callback received when the frontend's state changes. 761 */ 762 static void frontend_changed(struct xenbus_device *dev, 763 enum xenbus_state frontend_state) 764 { 765 struct backend_info *be = dev_get_drvdata(&dev->dev); 766 int err; 767 768 pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state)); 769 770 switch (frontend_state) { 771 case XenbusStateInitialising: 772 if (dev->state == XenbusStateClosed) { 773 pr_info("%s: prepare for reconnect\n", dev->nodename); 774 xenbus_switch_state(dev, XenbusStateInitWait); 775 } 776 break; 777 778 case XenbusStateInitialised: 779 case XenbusStateConnected: 780 /* 781 * Ensure we connect even when two watches fire in 782 * close succession and we miss the intermediate value 783 * of frontend_state. 784 */ 785 if (dev->state == XenbusStateConnected) 786 break; 787 788 /* 789 * Enforce precondition before potential leak point. 790 * xen_blkif_disconnect() is idempotent. 791 */ 792 err = xen_blkif_disconnect(be->blkif); 793 if (err) { 794 xenbus_dev_fatal(dev, err, "pending I/O"); 795 break; 796 } 797 798 err = connect_ring(be); 799 if (err) { 800 /* 801 * Clean up so that memory resources can be used by 802 * other devices. connect_ring reported already error. 803 */ 804 xen_blkif_disconnect(be->blkif); 805 break; 806 } 807 xen_update_blkif_status(be->blkif); 808 break; 809 810 case XenbusStateClosing: 811 xenbus_switch_state(dev, XenbusStateClosing); 812 break; 813 814 case XenbusStateClosed: 815 xen_blkif_disconnect(be->blkif); 816 xenbus_switch_state(dev, XenbusStateClosed); 817 if (xenbus_dev_is_online(dev)) 818 break; 819 /* fall through */ 820 /* if not online */ 821 case XenbusStateUnknown: 822 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */ 823 device_unregister(&dev->dev); 824 break; 825 826 default: 827 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", 828 frontend_state); 829 break; 830 } 831 } 832 833 834 /* ** Connection ** */ 835 836 837 /* 838 * Write the physical details regarding the block device to the store, and 839 * switch to Connected state. 840 */ 841 static void connect(struct backend_info *be) 842 { 843 struct xenbus_transaction xbt; 844 int err; 845 struct xenbus_device *dev = be->dev; 846 847 pr_debug("%s %s\n", __func__, dev->otherend); 848 849 /* Supply the information about the device the frontend needs */ 850 again: 851 err = xenbus_transaction_start(&xbt); 852 if (err) { 853 xenbus_dev_fatal(dev, err, "starting transaction"); 854 return; 855 } 856 857 /* If we can't advertise it is OK. */ 858 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support); 859 860 xen_blkbk_discard(xbt, be); 861 862 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); 863 864 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1); 865 if (err) { 866 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", 867 dev->nodename); 868 goto abort; 869 } 870 871 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 872 (unsigned long long)vbd_sz(&be->blkif->vbd)); 873 if (err) { 874 xenbus_dev_fatal(dev, err, "writing %s/sectors", 875 dev->nodename); 876 goto abort; 877 } 878 879 /* FIXME: use a typename instead */ 880 err = xenbus_printf(xbt, dev->nodename, "info", "%u", 881 be->blkif->vbd.type | 882 (be->blkif->vbd.readonly ? VDISK_READONLY : 0)); 883 if (err) { 884 xenbus_dev_fatal(dev, err, "writing %s/info", 885 dev->nodename); 886 goto abort; 887 } 888 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu", 889 (unsigned long) 890 bdev_logical_block_size(be->blkif->vbd.bdev)); 891 if (err) { 892 xenbus_dev_fatal(dev, err, "writing %s/sector-size", 893 dev->nodename); 894 goto abort; 895 } 896 err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u", 897 bdev_physical_block_size(be->blkif->vbd.bdev)); 898 if (err) 899 xenbus_dev_error(dev, err, "writing %s/physical-sector-size", 900 dev->nodename); 901 902 err = xenbus_transaction_end(xbt, 0); 903 if (err == -EAGAIN) 904 goto again; 905 if (err) 906 xenbus_dev_fatal(dev, err, "ending transaction"); 907 908 err = xenbus_switch_state(dev, XenbusStateConnected); 909 if (err) 910 xenbus_dev_fatal(dev, err, "%s: switching to Connected state", 911 dev->nodename); 912 913 return; 914 abort: 915 xenbus_transaction_end(xbt, 1); 916 } 917 918 /* 919 * Each ring may have multi pages, depends on "ring-page-order". 920 */ 921 static int read_per_ring_refs(struct xen_blkif_ring *ring, const char *dir) 922 { 923 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS]; 924 struct pending_req *req, *n; 925 int err, i, j; 926 struct xen_blkif *blkif = ring->blkif; 927 struct xenbus_device *dev = blkif->be->dev; 928 unsigned int ring_page_order, nr_grefs, evtchn; 929 930 err = xenbus_scanf(XBT_NIL, dir, "event-channel", "%u", 931 &evtchn); 932 if (err != 1) { 933 err = -EINVAL; 934 xenbus_dev_fatal(dev, err, "reading %s/event-channel", dir); 935 return err; 936 } 937 938 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u", 939 &ring_page_order); 940 if (err != 1) { 941 err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u", &ring_ref[0]); 942 if (err != 1) { 943 err = -EINVAL; 944 xenbus_dev_fatal(dev, err, "reading %s/ring-ref", dir); 945 return err; 946 } 947 nr_grefs = 1; 948 } else { 949 unsigned int i; 950 951 if (ring_page_order > xen_blkif_max_ring_order) { 952 err = -EINVAL; 953 xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d", 954 dir, ring_page_order, 955 xen_blkif_max_ring_order); 956 return err; 957 } 958 959 nr_grefs = 1 << ring_page_order; 960 for (i = 0; i < nr_grefs; i++) { 961 char ring_ref_name[RINGREF_NAME_LEN]; 962 963 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 964 err = xenbus_scanf(XBT_NIL, dir, ring_ref_name, 965 "%u", &ring_ref[i]); 966 if (err != 1) { 967 err = -EINVAL; 968 xenbus_dev_fatal(dev, err, "reading %s/%s", 969 dir, ring_ref_name); 970 return err; 971 } 972 } 973 } 974 blkif->nr_ring_pages = nr_grefs; 975 976 for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) { 977 req = kzalloc(sizeof(*req), GFP_KERNEL); 978 if (!req) 979 goto fail; 980 list_add_tail(&req->free_list, &ring->pending_free); 981 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) { 982 req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL); 983 if (!req->segments[j]) 984 goto fail; 985 } 986 for (j = 0; j < MAX_INDIRECT_PAGES; j++) { 987 req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]), 988 GFP_KERNEL); 989 if (!req->indirect_pages[j]) 990 goto fail; 991 } 992 } 993 994 /* Map the shared frame, irq etc. */ 995 err = xen_blkif_map(ring, ring_ref, nr_grefs, evtchn); 996 if (err) { 997 xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn); 998 return err; 999 } 1000 1001 return 0; 1002 1003 fail: 1004 list_for_each_entry_safe(req, n, &ring->pending_free, free_list) { 1005 list_del(&req->free_list); 1006 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) { 1007 if (!req->segments[j]) 1008 break; 1009 kfree(req->segments[j]); 1010 } 1011 for (j = 0; j < MAX_INDIRECT_PAGES; j++) { 1012 if (!req->indirect_pages[j]) 1013 break; 1014 kfree(req->indirect_pages[j]); 1015 } 1016 kfree(req); 1017 } 1018 return -ENOMEM; 1019 1020 } 1021 1022 static int connect_ring(struct backend_info *be) 1023 { 1024 struct xenbus_device *dev = be->dev; 1025 unsigned int pers_grants; 1026 char protocol[64] = ""; 1027 int err, i; 1028 char *xspath; 1029 size_t xspathsize; 1030 const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */ 1031 unsigned int requested_num_queues = 0; 1032 1033 pr_debug("%s %s\n", __func__, dev->otherend); 1034 1035 be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT; 1036 err = xenbus_scanf(XBT_NIL, dev->otherend, "protocol", 1037 "%63s", protocol); 1038 if (err <= 0) 1039 strcpy(protocol, "unspecified, assuming default"); 1040 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) 1041 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; 1042 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32)) 1043 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32; 1044 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64)) 1045 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64; 1046 else { 1047 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); 1048 return -ENOSYS; 1049 } 1050 pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent", 1051 0); 1052 be->blkif->vbd.feature_gnt_persistent = pers_grants; 1053 be->blkif->vbd.overflow_max_grants = 0; 1054 1055 /* 1056 * Read the number of hardware queues from frontend. 1057 */ 1058 requested_num_queues = xenbus_read_unsigned(dev->otherend, 1059 "multi-queue-num-queues", 1060 1); 1061 if (requested_num_queues > xenblk_max_queues 1062 || requested_num_queues == 0) { 1063 /* Buggy or malicious guest. */ 1064 xenbus_dev_fatal(dev, err, 1065 "guest requested %u queues, exceeding the maximum of %u.", 1066 requested_num_queues, xenblk_max_queues); 1067 return -ENOSYS; 1068 } 1069 be->blkif->nr_rings = requested_num_queues; 1070 if (xen_blkif_alloc_rings(be->blkif)) 1071 return -ENOMEM; 1072 1073 pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename, 1074 be->blkif->nr_rings, be->blkif->blk_protocol, protocol, 1075 pers_grants ? "persistent grants" : ""); 1076 1077 if (be->blkif->nr_rings == 1) 1078 return read_per_ring_refs(&be->blkif->rings[0], dev->otherend); 1079 else { 1080 xspathsize = strlen(dev->otherend) + xenstore_path_ext_size; 1081 xspath = kmalloc(xspathsize, GFP_KERNEL); 1082 if (!xspath) { 1083 xenbus_dev_fatal(dev, -ENOMEM, "reading ring references"); 1084 return -ENOMEM; 1085 } 1086 1087 for (i = 0; i < be->blkif->nr_rings; i++) { 1088 memset(xspath, 0, xspathsize); 1089 snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend, i); 1090 err = read_per_ring_refs(&be->blkif->rings[i], xspath); 1091 if (err) { 1092 kfree(xspath); 1093 return err; 1094 } 1095 } 1096 kfree(xspath); 1097 } 1098 return 0; 1099 } 1100 1101 static const struct xenbus_device_id xen_blkbk_ids[] = { 1102 { "vbd" }, 1103 { "" } 1104 }; 1105 1106 static struct xenbus_driver xen_blkbk_driver = { 1107 .ids = xen_blkbk_ids, 1108 .probe = xen_blkbk_probe, 1109 .remove = xen_blkbk_remove, 1110 .otherend_changed = frontend_changed 1111 }; 1112 1113 int xen_blkif_xenbus_init(void) 1114 { 1115 return xenbus_register_backend(&xen_blkbk_driver); 1116 } 1117