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