1 /* Xenbus code for blkif backend 2 Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au> 3 Copyright (C) 2005 XenSource Ltd 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 2 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 */ 16 17 #define pr_fmt(fmt) "xen-blkback: " fmt 18 19 #include <stdarg.h> 20 #include <linux/module.h> 21 #include <linux/kthread.h> 22 #include <xen/events.h> 23 #include <xen/grant_table.h> 24 #include "common.h" 25 26 /* Enlarge the array size in order to fully show blkback name. */ 27 #define BLKBACK_NAME_LEN (20) 28 #define RINGREF_NAME_LEN (20) 29 30 struct backend_info { 31 struct xenbus_device *dev; 32 struct xen_blkif *blkif; 33 struct xenbus_watch backend_watch; 34 unsigned major; 35 unsigned minor; 36 char *mode; 37 }; 38 39 static struct kmem_cache *xen_blkif_cachep; 40 static void connect(struct backend_info *); 41 static int connect_ring(struct backend_info *); 42 static void backend_changed(struct xenbus_watch *, const char **, 43 unsigned int); 44 static void xen_blkif_free(struct xen_blkif *blkif); 45 static void xen_vbd_free(struct xen_vbd *vbd); 46 47 struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be) 48 { 49 return be->dev; 50 } 51 52 /* 53 * The last request could free the device from softirq context and 54 * xen_blkif_free() can sleep. 55 */ 56 static void xen_blkif_deferred_free(struct work_struct *work) 57 { 58 struct xen_blkif *blkif; 59 60 blkif = container_of(work, struct xen_blkif, free_work); 61 xen_blkif_free(blkif); 62 } 63 64 static int blkback_name(struct xen_blkif *blkif, char *buf) 65 { 66 char *devpath, *devname; 67 struct xenbus_device *dev = blkif->be->dev; 68 69 devpath = xenbus_read(XBT_NIL, dev->nodename, "dev", NULL); 70 if (IS_ERR(devpath)) 71 return PTR_ERR(devpath); 72 73 devname = strstr(devpath, "/dev/"); 74 if (devname != NULL) 75 devname += strlen("/dev/"); 76 else 77 devname = devpath; 78 79 snprintf(buf, BLKBACK_NAME_LEN, "blkback.%d.%s", blkif->domid, devname); 80 kfree(devpath); 81 82 return 0; 83 } 84 85 static void xen_update_blkif_status(struct xen_blkif *blkif) 86 { 87 int err; 88 char name[BLKBACK_NAME_LEN]; 89 90 /* Not ready to connect? */ 91 if (!blkif->irq || !blkif->vbd.bdev) 92 return; 93 94 /* Already connected? */ 95 if (blkif->be->dev->state == XenbusStateConnected) 96 return; 97 98 /* Attempt to connect: exit if we fail to. */ 99 connect(blkif->be); 100 if (blkif->be->dev->state != XenbusStateConnected) 101 return; 102 103 err = blkback_name(blkif, name); 104 if (err) { 105 xenbus_dev_error(blkif->be->dev, err, "get blkback dev name"); 106 return; 107 } 108 109 err = filemap_write_and_wait(blkif->vbd.bdev->bd_inode->i_mapping); 110 if (err) { 111 xenbus_dev_error(blkif->be->dev, err, "block flush"); 112 return; 113 } 114 invalidate_inode_pages2(blkif->vbd.bdev->bd_inode->i_mapping); 115 116 blkif->xenblkd = kthread_run(xen_blkif_schedule, blkif, "%s", name); 117 if (IS_ERR(blkif->xenblkd)) { 118 err = PTR_ERR(blkif->xenblkd); 119 blkif->xenblkd = NULL; 120 xenbus_dev_error(blkif->be->dev, err, "start xenblkd"); 121 return; 122 } 123 } 124 125 static struct xen_blkif *xen_blkif_alloc(domid_t domid) 126 { 127 struct xen_blkif *blkif; 128 129 BUILD_BUG_ON(MAX_INDIRECT_PAGES > BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST); 130 131 blkif = kmem_cache_zalloc(xen_blkif_cachep, GFP_KERNEL); 132 if (!blkif) 133 return ERR_PTR(-ENOMEM); 134 135 blkif->domid = domid; 136 spin_lock_init(&blkif->blk_ring_lock); 137 atomic_set(&blkif->refcnt, 1); 138 init_waitqueue_head(&blkif->wq); 139 init_completion(&blkif->drain_complete); 140 atomic_set(&blkif->drain, 0); 141 blkif->st_print = jiffies; 142 blkif->persistent_gnts.rb_node = NULL; 143 spin_lock_init(&blkif->free_pages_lock); 144 INIT_LIST_HEAD(&blkif->free_pages); 145 INIT_LIST_HEAD(&blkif->persistent_purge_list); 146 blkif->free_pages_num = 0; 147 atomic_set(&blkif->persistent_gnt_in_use, 0); 148 atomic_set(&blkif->inflight, 0); 149 INIT_WORK(&blkif->persistent_purge_work, xen_blkbk_unmap_purged_grants); 150 151 INIT_LIST_HEAD(&blkif->pending_free); 152 INIT_WORK(&blkif->free_work, xen_blkif_deferred_free); 153 spin_lock_init(&blkif->pending_free_lock); 154 init_waitqueue_head(&blkif->pending_free_wq); 155 init_waitqueue_head(&blkif->shutdown_wq); 156 157 return blkif; 158 } 159 160 static int xen_blkif_map(struct xen_blkif *blkif, grant_ref_t *gref, 161 unsigned int nr_grefs, unsigned int evtchn) 162 { 163 int err; 164 165 /* Already connected through? */ 166 if (blkif->irq) 167 return 0; 168 169 err = xenbus_map_ring_valloc(blkif->be->dev, gref, nr_grefs, 170 &blkif->blk_ring); 171 if (err < 0) 172 return err; 173 174 switch (blkif->blk_protocol) { 175 case BLKIF_PROTOCOL_NATIVE: 176 { 177 struct blkif_sring *sring; 178 sring = (struct blkif_sring *)blkif->blk_ring; 179 BACK_RING_INIT(&blkif->blk_rings.native, sring, PAGE_SIZE * nr_grefs); 180 break; 181 } 182 case BLKIF_PROTOCOL_X86_32: 183 { 184 struct blkif_x86_32_sring *sring_x86_32; 185 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring; 186 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, PAGE_SIZE * nr_grefs); 187 break; 188 } 189 case BLKIF_PROTOCOL_X86_64: 190 { 191 struct blkif_x86_64_sring *sring_x86_64; 192 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring; 193 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, PAGE_SIZE * nr_grefs); 194 break; 195 } 196 default: 197 BUG(); 198 } 199 200 err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn, 201 xen_blkif_be_int, 0, 202 "blkif-backend", blkif); 203 if (err < 0) { 204 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); 205 blkif->blk_rings.common.sring = NULL; 206 return err; 207 } 208 blkif->irq = err; 209 210 return 0; 211 } 212 213 static int xen_blkif_disconnect(struct xen_blkif *blkif) 214 { 215 struct pending_req *req, *n; 216 int i = 0, j; 217 218 if (blkif->xenblkd) { 219 kthread_stop(blkif->xenblkd); 220 wake_up(&blkif->shutdown_wq); 221 blkif->xenblkd = NULL; 222 } 223 224 /* The above kthread_stop() guarantees that at this point we 225 * don't have any discard_io or other_io requests. So, checking 226 * for inflight IO is enough. 227 */ 228 if (atomic_read(&blkif->inflight) > 0) 229 return -EBUSY; 230 231 if (blkif->irq) { 232 unbind_from_irqhandler(blkif->irq, blkif); 233 blkif->irq = 0; 234 } 235 236 if (blkif->blk_rings.common.sring) { 237 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); 238 blkif->blk_rings.common.sring = NULL; 239 } 240 241 /* Remove all persistent grants and the cache of ballooned pages. */ 242 xen_blkbk_free_caches(blkif); 243 244 /* Check that there is no request in use */ 245 list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) { 246 list_del(&req->free_list); 247 248 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) 249 kfree(req->segments[j]); 250 251 for (j = 0; j < MAX_INDIRECT_PAGES; j++) 252 kfree(req->indirect_pages[j]); 253 254 kfree(req); 255 i++; 256 } 257 258 WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages)); 259 blkif->nr_ring_pages = 0; 260 261 return 0; 262 } 263 264 static void xen_blkif_free(struct xen_blkif *blkif) 265 { 266 267 xen_blkif_disconnect(blkif); 268 xen_vbd_free(&blkif->vbd); 269 270 /* Make sure everything is drained before shutting down */ 271 BUG_ON(blkif->persistent_gnt_c != 0); 272 BUG_ON(atomic_read(&blkif->persistent_gnt_in_use) != 0); 273 BUG_ON(blkif->free_pages_num != 0); 274 BUG_ON(!list_empty(&blkif->persistent_purge_list)); 275 BUG_ON(!list_empty(&blkif->free_pages)); 276 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts)); 277 278 kmem_cache_free(xen_blkif_cachep, blkif); 279 } 280 281 int __init xen_blkif_interface_init(void) 282 { 283 xen_blkif_cachep = kmem_cache_create("blkif_cache", 284 sizeof(struct xen_blkif), 285 0, 0, NULL); 286 if (!xen_blkif_cachep) 287 return -ENOMEM; 288 289 return 0; 290 } 291 292 /* 293 * sysfs interface for VBD I/O requests 294 */ 295 296 #define VBD_SHOW(name, format, args...) \ 297 static ssize_t show_##name(struct device *_dev, \ 298 struct device_attribute *attr, \ 299 char *buf) \ 300 { \ 301 struct xenbus_device *dev = to_xenbus_device(_dev); \ 302 struct backend_info *be = dev_get_drvdata(&dev->dev); \ 303 \ 304 return sprintf(buf, format, ##args); \ 305 } \ 306 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) 307 308 VBD_SHOW(oo_req, "%llu\n", be->blkif->st_oo_req); 309 VBD_SHOW(rd_req, "%llu\n", be->blkif->st_rd_req); 310 VBD_SHOW(wr_req, "%llu\n", be->blkif->st_wr_req); 311 VBD_SHOW(f_req, "%llu\n", be->blkif->st_f_req); 312 VBD_SHOW(ds_req, "%llu\n", be->blkif->st_ds_req); 313 VBD_SHOW(rd_sect, "%llu\n", be->blkif->st_rd_sect); 314 VBD_SHOW(wr_sect, "%llu\n", be->blkif->st_wr_sect); 315 316 static struct attribute *xen_vbdstat_attrs[] = { 317 &dev_attr_oo_req.attr, 318 &dev_attr_rd_req.attr, 319 &dev_attr_wr_req.attr, 320 &dev_attr_f_req.attr, 321 &dev_attr_ds_req.attr, 322 &dev_attr_rd_sect.attr, 323 &dev_attr_wr_sect.attr, 324 NULL 325 }; 326 327 static struct attribute_group xen_vbdstat_group = { 328 .name = "statistics", 329 .attrs = xen_vbdstat_attrs, 330 }; 331 332 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor); 333 VBD_SHOW(mode, "%s\n", be->mode); 334 335 static int xenvbd_sysfs_addif(struct xenbus_device *dev) 336 { 337 int error; 338 339 error = device_create_file(&dev->dev, &dev_attr_physical_device); 340 if (error) 341 goto fail1; 342 343 error = device_create_file(&dev->dev, &dev_attr_mode); 344 if (error) 345 goto fail2; 346 347 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group); 348 if (error) 349 goto fail3; 350 351 return 0; 352 353 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 354 fail2: device_remove_file(&dev->dev, &dev_attr_mode); 355 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device); 356 return error; 357 } 358 359 static void xenvbd_sysfs_delif(struct xenbus_device *dev) 360 { 361 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 362 device_remove_file(&dev->dev, &dev_attr_mode); 363 device_remove_file(&dev->dev, &dev_attr_physical_device); 364 } 365 366 367 static void xen_vbd_free(struct xen_vbd *vbd) 368 { 369 if (vbd->bdev) 370 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE); 371 vbd->bdev = NULL; 372 } 373 374 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, 375 unsigned major, unsigned minor, int readonly, 376 int cdrom) 377 { 378 struct xen_vbd *vbd; 379 struct block_device *bdev; 380 struct request_queue *q; 381 382 vbd = &blkif->vbd; 383 vbd->handle = handle; 384 vbd->readonly = readonly; 385 vbd->type = 0; 386 387 vbd->pdevice = MKDEV(major, minor); 388 389 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ? 390 FMODE_READ : FMODE_WRITE, NULL); 391 392 if (IS_ERR(bdev)) { 393 pr_warn("xen_vbd_create: device %08x could not be opened\n", 394 vbd->pdevice); 395 return -ENOENT; 396 } 397 398 vbd->bdev = bdev; 399 if (vbd->bdev->bd_disk == NULL) { 400 pr_warn("xen_vbd_create: device %08x doesn't exist\n", 401 vbd->pdevice); 402 xen_vbd_free(vbd); 403 return -ENOENT; 404 } 405 vbd->size = vbd_sz(vbd); 406 407 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom) 408 vbd->type |= VDISK_CDROM; 409 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE) 410 vbd->type |= VDISK_REMOVABLE; 411 412 q = bdev_get_queue(bdev); 413 if (q && q->flush_flags) 414 vbd->flush_support = true; 415 416 if (q && blk_queue_secdiscard(q)) 417 vbd->discard_secure = true; 418 419 pr_debug("Successful creation of handle=%04x (dom=%u)\n", 420 handle, blkif->domid); 421 return 0; 422 } 423 static int xen_blkbk_remove(struct xenbus_device *dev) 424 { 425 struct backend_info *be = dev_get_drvdata(&dev->dev); 426 427 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 428 429 if (be->major || be->minor) 430 xenvbd_sysfs_delif(dev); 431 432 if (be->backend_watch.node) { 433 unregister_xenbus_watch(&be->backend_watch); 434 kfree(be->backend_watch.node); 435 be->backend_watch.node = NULL; 436 } 437 438 dev_set_drvdata(&dev->dev, NULL); 439 440 if (be->blkif) { 441 xen_blkif_disconnect(be->blkif); 442 xen_blkif_put(be->blkif); 443 } 444 445 kfree(be->mode); 446 kfree(be); 447 return 0; 448 } 449 450 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt, 451 struct backend_info *be, int state) 452 { 453 struct xenbus_device *dev = be->dev; 454 int err; 455 456 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache", 457 "%d", state); 458 if (err) 459 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err); 460 461 return err; 462 } 463 464 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be) 465 { 466 struct xenbus_device *dev = be->dev; 467 struct xen_blkif *blkif = be->blkif; 468 int err; 469 int state = 0, discard_enable; 470 struct block_device *bdev = be->blkif->vbd.bdev; 471 struct request_queue *q = bdev_get_queue(bdev); 472 473 err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d", 474 &discard_enable); 475 if (err == 1 && !discard_enable) 476 return; 477 478 if (blk_queue_discard(q)) { 479 err = xenbus_printf(xbt, dev->nodename, 480 "discard-granularity", "%u", 481 q->limits.discard_granularity); 482 if (err) { 483 dev_warn(&dev->dev, "writing discard-granularity (%d)", err); 484 return; 485 } 486 err = xenbus_printf(xbt, dev->nodename, 487 "discard-alignment", "%u", 488 q->limits.discard_alignment); 489 if (err) { 490 dev_warn(&dev->dev, "writing discard-alignment (%d)", err); 491 return; 492 } 493 state = 1; 494 /* Optional. */ 495 err = xenbus_printf(xbt, dev->nodename, 496 "discard-secure", "%d", 497 blkif->vbd.discard_secure); 498 if (err) { 499 dev_warn(&dev->dev, "writing discard-secure (%d)", err); 500 return; 501 } 502 } 503 err = xenbus_printf(xbt, dev->nodename, "feature-discard", 504 "%d", state); 505 if (err) 506 dev_warn(&dev->dev, "writing feature-discard (%d)", err); 507 } 508 int xen_blkbk_barrier(struct xenbus_transaction xbt, 509 struct backend_info *be, int state) 510 { 511 struct xenbus_device *dev = be->dev; 512 int err; 513 514 err = xenbus_printf(xbt, dev->nodename, "feature-barrier", 515 "%d", state); 516 if (err) 517 dev_warn(&dev->dev, "writing feature-barrier (%d)", err); 518 519 return err; 520 } 521 522 /* 523 * Entry point to this code when a new device is created. Allocate the basic 524 * structures, and watch the store waiting for the hotplug scripts to tell us 525 * the device's physical major and minor numbers. Switch to InitWait. 526 */ 527 static int xen_blkbk_probe(struct xenbus_device *dev, 528 const struct xenbus_device_id *id) 529 { 530 int err; 531 struct backend_info *be = kzalloc(sizeof(struct backend_info), 532 GFP_KERNEL); 533 534 /* match the pr_debug in xen_blkbk_remove */ 535 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 536 537 if (!be) { 538 xenbus_dev_fatal(dev, -ENOMEM, 539 "allocating backend structure"); 540 return -ENOMEM; 541 } 542 be->dev = dev; 543 dev_set_drvdata(&dev->dev, be); 544 545 be->blkif = xen_blkif_alloc(dev->otherend_id); 546 if (IS_ERR(be->blkif)) { 547 err = PTR_ERR(be->blkif); 548 be->blkif = NULL; 549 xenbus_dev_fatal(dev, err, "creating block interface"); 550 goto fail; 551 } 552 553 /* setup back pointer */ 554 be->blkif->be = be; 555 556 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed, 557 "%s/%s", dev->nodename, "physical-device"); 558 if (err) 559 goto fail; 560 561 err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u", 562 xen_blkif_max_ring_order); 563 if (err) 564 pr_warn("%s write out 'max-ring-page-order' failed\n", __func__); 565 566 err = xenbus_switch_state(dev, XenbusStateInitWait); 567 if (err) 568 goto fail; 569 570 return 0; 571 572 fail: 573 pr_warn("%s failed\n", __func__); 574 xen_blkbk_remove(dev); 575 return err; 576 } 577 578 579 /* 580 * Callback received when the hotplug scripts have placed the physical-device 581 * node. Read it and the mode node, and create a vbd. If the frontend is 582 * ready, connect. 583 */ 584 static void backend_changed(struct xenbus_watch *watch, 585 const char **vec, unsigned int len) 586 { 587 int err; 588 unsigned major; 589 unsigned minor; 590 struct backend_info *be 591 = container_of(watch, struct backend_info, backend_watch); 592 struct xenbus_device *dev = be->dev; 593 int cdrom = 0; 594 unsigned long handle; 595 char *device_type; 596 597 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 598 599 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x", 600 &major, &minor); 601 if (XENBUS_EXIST_ERR(err)) { 602 /* 603 * Since this watch will fire once immediately after it is 604 * registered, we expect this. Ignore it, and wait for the 605 * hotplug scripts. 606 */ 607 return; 608 } 609 if (err != 2) { 610 xenbus_dev_fatal(dev, err, "reading physical-device"); 611 return; 612 } 613 614 if (be->major | be->minor) { 615 if (be->major != major || be->minor != minor) 616 pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n", 617 be->major, be->minor, major, minor); 618 return; 619 } 620 621 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL); 622 if (IS_ERR(be->mode)) { 623 err = PTR_ERR(be->mode); 624 be->mode = NULL; 625 xenbus_dev_fatal(dev, err, "reading mode"); 626 return; 627 } 628 629 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL); 630 if (!IS_ERR(device_type)) { 631 cdrom = strcmp(device_type, "cdrom") == 0; 632 kfree(device_type); 633 } 634 635 /* Front end dir is a number, which is used as the handle. */ 636 err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle); 637 if (err) 638 return; 639 640 be->major = major; 641 be->minor = minor; 642 643 err = xen_vbd_create(be->blkif, handle, major, minor, 644 !strchr(be->mode, 'w'), cdrom); 645 646 if (err) 647 xenbus_dev_fatal(dev, err, "creating vbd structure"); 648 else { 649 err = xenvbd_sysfs_addif(dev); 650 if (err) { 651 xen_vbd_free(&be->blkif->vbd); 652 xenbus_dev_fatal(dev, err, "creating sysfs entries"); 653 } 654 } 655 656 if (err) { 657 kfree(be->mode); 658 be->mode = NULL; 659 be->major = 0; 660 be->minor = 0; 661 } else { 662 /* We're potentially connected now */ 663 xen_update_blkif_status(be->blkif); 664 } 665 } 666 667 668 /* 669 * Callback received when the frontend's state changes. 670 */ 671 static void frontend_changed(struct xenbus_device *dev, 672 enum xenbus_state frontend_state) 673 { 674 struct backend_info *be = dev_get_drvdata(&dev->dev); 675 int err; 676 677 pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state)); 678 679 switch (frontend_state) { 680 case XenbusStateInitialising: 681 if (dev->state == XenbusStateClosed) { 682 pr_info("%s: prepare for reconnect\n", dev->nodename); 683 xenbus_switch_state(dev, XenbusStateInitWait); 684 } 685 break; 686 687 case XenbusStateInitialised: 688 case XenbusStateConnected: 689 /* 690 * Ensure we connect even when two watches fire in 691 * close succession and we miss the intermediate value 692 * of frontend_state. 693 */ 694 if (dev->state == XenbusStateConnected) 695 break; 696 697 /* 698 * Enforce precondition before potential leak point. 699 * xen_blkif_disconnect() is idempotent. 700 */ 701 err = xen_blkif_disconnect(be->blkif); 702 if (err) { 703 xenbus_dev_fatal(dev, err, "pending I/O"); 704 break; 705 } 706 707 err = connect_ring(be); 708 if (err) 709 break; 710 xen_update_blkif_status(be->blkif); 711 break; 712 713 case XenbusStateClosing: 714 xenbus_switch_state(dev, XenbusStateClosing); 715 break; 716 717 case XenbusStateClosed: 718 xen_blkif_disconnect(be->blkif); 719 xenbus_switch_state(dev, XenbusStateClosed); 720 if (xenbus_dev_is_online(dev)) 721 break; 722 /* fall through if not online */ 723 case XenbusStateUnknown: 724 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */ 725 device_unregister(&dev->dev); 726 break; 727 728 default: 729 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", 730 frontend_state); 731 break; 732 } 733 } 734 735 736 /* ** Connection ** */ 737 738 739 /* 740 * Write the physical details regarding the block device to the store, and 741 * switch to Connected state. 742 */ 743 static void connect(struct backend_info *be) 744 { 745 struct xenbus_transaction xbt; 746 int err; 747 struct xenbus_device *dev = be->dev; 748 749 pr_debug("%s %s\n", __func__, dev->otherend); 750 751 /* Supply the information about the device the frontend needs */ 752 again: 753 err = xenbus_transaction_start(&xbt); 754 if (err) { 755 xenbus_dev_fatal(dev, err, "starting transaction"); 756 return; 757 } 758 759 /* If we can't advertise it is OK. */ 760 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support); 761 762 xen_blkbk_discard(xbt, be); 763 764 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); 765 766 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1); 767 if (err) { 768 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", 769 dev->nodename); 770 goto abort; 771 } 772 err = xenbus_printf(xbt, dev->nodename, "feature-max-indirect-segments", "%u", 773 MAX_INDIRECT_SEGMENTS); 774 if (err) 775 dev_warn(&dev->dev, "writing %s/feature-max-indirect-segments (%d)", 776 dev->nodename, err); 777 778 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 779 (unsigned long long)vbd_sz(&be->blkif->vbd)); 780 if (err) { 781 xenbus_dev_fatal(dev, err, "writing %s/sectors", 782 dev->nodename); 783 goto abort; 784 } 785 786 /* FIXME: use a typename instead */ 787 err = xenbus_printf(xbt, dev->nodename, "info", "%u", 788 be->blkif->vbd.type | 789 (be->blkif->vbd.readonly ? VDISK_READONLY : 0)); 790 if (err) { 791 xenbus_dev_fatal(dev, err, "writing %s/info", 792 dev->nodename); 793 goto abort; 794 } 795 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu", 796 (unsigned long) 797 bdev_logical_block_size(be->blkif->vbd.bdev)); 798 if (err) { 799 xenbus_dev_fatal(dev, err, "writing %s/sector-size", 800 dev->nodename); 801 goto abort; 802 } 803 err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u", 804 bdev_physical_block_size(be->blkif->vbd.bdev)); 805 if (err) 806 xenbus_dev_error(dev, err, "writing %s/physical-sector-size", 807 dev->nodename); 808 809 err = xenbus_transaction_end(xbt, 0); 810 if (err == -EAGAIN) 811 goto again; 812 if (err) 813 xenbus_dev_fatal(dev, err, "ending transaction"); 814 815 err = xenbus_switch_state(dev, XenbusStateConnected); 816 if (err) 817 xenbus_dev_fatal(dev, err, "%s: switching to Connected state", 818 dev->nodename); 819 820 return; 821 abort: 822 xenbus_transaction_end(xbt, 1); 823 } 824 825 826 static int connect_ring(struct backend_info *be) 827 { 828 struct xenbus_device *dev = be->dev; 829 unsigned int ring_ref[XENBUS_MAX_RING_PAGES]; 830 unsigned int evtchn, nr_grefs, ring_page_order; 831 unsigned int pers_grants; 832 char protocol[64] = ""; 833 struct pending_req *req, *n; 834 int err, i, j; 835 836 pr_debug("%s %s\n", __func__, dev->otherend); 837 838 err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel", "%u", 839 &evtchn); 840 if (err != 1) { 841 err = -EINVAL; 842 xenbus_dev_fatal(dev, err, "reading %s/event-channel", 843 dev->otherend); 844 return err; 845 } 846 pr_info("event-channel %u\n", evtchn); 847 848 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u", 849 &ring_page_order); 850 if (err != 1) { 851 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", 852 "%u", &ring_ref[0]); 853 if (err != 1) { 854 err = -EINVAL; 855 xenbus_dev_fatal(dev, err, "reading %s/ring-ref", 856 dev->otherend); 857 return err; 858 } 859 nr_grefs = 1; 860 pr_info("%s:using single page: ring-ref %d\n", dev->otherend, 861 ring_ref[0]); 862 } else { 863 unsigned int i; 864 865 if (ring_page_order > xen_blkif_max_ring_order) { 866 err = -EINVAL; 867 xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d", 868 dev->otherend, ring_page_order, 869 xen_blkif_max_ring_order); 870 return err; 871 } 872 873 nr_grefs = 1 << ring_page_order; 874 for (i = 0; i < nr_grefs; i++) { 875 char ring_ref_name[RINGREF_NAME_LEN]; 876 877 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 878 err = xenbus_scanf(XBT_NIL, dev->otherend, ring_ref_name, 879 "%u", &ring_ref[i]); 880 if (err != 1) { 881 err = -EINVAL; 882 xenbus_dev_fatal(dev, err, "reading %s/%s", 883 dev->otherend, ring_ref_name); 884 return err; 885 } 886 pr_info("ring-ref%u: %u\n", i, ring_ref[i]); 887 } 888 } 889 890 be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT; 891 err = xenbus_gather(XBT_NIL, dev->otherend, "protocol", 892 "%63s", protocol, NULL); 893 if (err) 894 strcpy(protocol, "unspecified, assuming default"); 895 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) 896 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; 897 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32)) 898 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32; 899 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64)) 900 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64; 901 else { 902 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); 903 return -1; 904 } 905 err = xenbus_gather(XBT_NIL, dev->otherend, 906 "feature-persistent", "%u", 907 &pers_grants, NULL); 908 if (err) 909 pers_grants = 0; 910 911 be->blkif->vbd.feature_gnt_persistent = pers_grants; 912 be->blkif->vbd.overflow_max_grants = 0; 913 be->blkif->nr_ring_pages = nr_grefs; 914 915 pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n", 916 nr_grefs, evtchn, be->blkif->blk_protocol, protocol, 917 pers_grants ? "persistent grants" : ""); 918 919 for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) { 920 req = kzalloc(sizeof(*req), GFP_KERNEL); 921 if (!req) 922 goto fail; 923 list_add_tail(&req->free_list, &be->blkif->pending_free); 924 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) { 925 req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL); 926 if (!req->segments[j]) 927 goto fail; 928 } 929 for (j = 0; j < MAX_INDIRECT_PAGES; j++) { 930 req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]), 931 GFP_KERNEL); 932 if (!req->indirect_pages[j]) 933 goto fail; 934 } 935 } 936 937 /* Map the shared frame, irq etc. */ 938 err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn); 939 if (err) { 940 xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn); 941 return err; 942 } 943 944 return 0; 945 946 fail: 947 list_for_each_entry_safe(req, n, &be->blkif->pending_free, free_list) { 948 list_del(&req->free_list); 949 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) { 950 if (!req->segments[j]) 951 break; 952 kfree(req->segments[j]); 953 } 954 for (j = 0; j < MAX_INDIRECT_PAGES; j++) { 955 if (!req->indirect_pages[j]) 956 break; 957 kfree(req->indirect_pages[j]); 958 } 959 kfree(req); 960 } 961 return -ENOMEM; 962 } 963 964 static const struct xenbus_device_id xen_blkbk_ids[] = { 965 { "vbd" }, 966 { "" } 967 }; 968 969 static struct xenbus_driver xen_blkbk_driver = { 970 .ids = xen_blkbk_ids, 971 .probe = xen_blkbk_probe, 972 .remove = xen_blkbk_remove, 973 .otherend_changed = frontend_changed 974 }; 975 976 int xen_blkif_xenbus_init(void) 977 { 978 return xenbus_register_backend(&xen_blkbk_driver); 979 } 980