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, 180 XEN_PAGE_SIZE * nr_grefs); 181 break; 182 } 183 case BLKIF_PROTOCOL_X86_32: 184 { 185 struct blkif_x86_32_sring *sring_x86_32; 186 sring_x86_32 = (struct blkif_x86_32_sring *)blkif->blk_ring; 187 BACK_RING_INIT(&blkif->blk_rings.x86_32, sring_x86_32, 188 XEN_PAGE_SIZE * nr_grefs); 189 break; 190 } 191 case BLKIF_PROTOCOL_X86_64: 192 { 193 struct blkif_x86_64_sring *sring_x86_64; 194 sring_x86_64 = (struct blkif_x86_64_sring *)blkif->blk_ring; 195 BACK_RING_INIT(&blkif->blk_rings.x86_64, sring_x86_64, 196 XEN_PAGE_SIZE * nr_grefs); 197 break; 198 } 199 default: 200 BUG(); 201 } 202 203 err = bind_interdomain_evtchn_to_irqhandler(blkif->domid, evtchn, 204 xen_blkif_be_int, 0, 205 "blkif-backend", blkif); 206 if (err < 0) { 207 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); 208 blkif->blk_rings.common.sring = NULL; 209 return err; 210 } 211 blkif->irq = err; 212 213 return 0; 214 } 215 216 static int xen_blkif_disconnect(struct xen_blkif *blkif) 217 { 218 struct pending_req *req, *n; 219 int i = 0, j; 220 221 if (blkif->xenblkd) { 222 kthread_stop(blkif->xenblkd); 223 wake_up(&blkif->shutdown_wq); 224 blkif->xenblkd = NULL; 225 } 226 227 /* The above kthread_stop() guarantees that at this point we 228 * don't have any discard_io or other_io requests. So, checking 229 * for inflight IO is enough. 230 */ 231 if (atomic_read(&blkif->inflight) > 0) 232 return -EBUSY; 233 234 if (blkif->irq) { 235 unbind_from_irqhandler(blkif->irq, blkif); 236 blkif->irq = 0; 237 } 238 239 if (blkif->blk_rings.common.sring) { 240 xenbus_unmap_ring_vfree(blkif->be->dev, blkif->blk_ring); 241 blkif->blk_rings.common.sring = NULL; 242 } 243 244 /* Remove all persistent grants and the cache of ballooned pages. */ 245 xen_blkbk_free_caches(blkif); 246 247 /* Check that there is no request in use */ 248 list_for_each_entry_safe(req, n, &blkif->pending_free, free_list) { 249 list_del(&req->free_list); 250 251 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) 252 kfree(req->segments[j]); 253 254 for (j = 0; j < MAX_INDIRECT_PAGES; j++) 255 kfree(req->indirect_pages[j]); 256 257 kfree(req); 258 i++; 259 } 260 261 WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages)); 262 blkif->nr_ring_pages = 0; 263 264 return 0; 265 } 266 267 static void xen_blkif_free(struct xen_blkif *blkif) 268 { 269 270 xen_blkif_disconnect(blkif); 271 xen_vbd_free(&blkif->vbd); 272 273 /* Make sure everything is drained before shutting down */ 274 BUG_ON(blkif->persistent_gnt_c != 0); 275 BUG_ON(atomic_read(&blkif->persistent_gnt_in_use) != 0); 276 BUG_ON(blkif->free_pages_num != 0); 277 BUG_ON(!list_empty(&blkif->persistent_purge_list)); 278 BUG_ON(!list_empty(&blkif->free_pages)); 279 BUG_ON(!RB_EMPTY_ROOT(&blkif->persistent_gnts)); 280 281 kmem_cache_free(xen_blkif_cachep, blkif); 282 } 283 284 int __init xen_blkif_interface_init(void) 285 { 286 xen_blkif_cachep = kmem_cache_create("blkif_cache", 287 sizeof(struct xen_blkif), 288 0, 0, NULL); 289 if (!xen_blkif_cachep) 290 return -ENOMEM; 291 292 return 0; 293 } 294 295 /* 296 * sysfs interface for VBD I/O requests 297 */ 298 299 #define VBD_SHOW(name, format, args...) \ 300 static ssize_t show_##name(struct device *_dev, \ 301 struct device_attribute *attr, \ 302 char *buf) \ 303 { \ 304 struct xenbus_device *dev = to_xenbus_device(_dev); \ 305 struct backend_info *be = dev_get_drvdata(&dev->dev); \ 306 \ 307 return sprintf(buf, format, ##args); \ 308 } \ 309 static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL) 310 311 VBD_SHOW(oo_req, "%llu\n", be->blkif->st_oo_req); 312 VBD_SHOW(rd_req, "%llu\n", be->blkif->st_rd_req); 313 VBD_SHOW(wr_req, "%llu\n", be->blkif->st_wr_req); 314 VBD_SHOW(f_req, "%llu\n", be->blkif->st_f_req); 315 VBD_SHOW(ds_req, "%llu\n", be->blkif->st_ds_req); 316 VBD_SHOW(rd_sect, "%llu\n", be->blkif->st_rd_sect); 317 VBD_SHOW(wr_sect, "%llu\n", be->blkif->st_wr_sect); 318 319 static struct attribute *xen_vbdstat_attrs[] = { 320 &dev_attr_oo_req.attr, 321 &dev_attr_rd_req.attr, 322 &dev_attr_wr_req.attr, 323 &dev_attr_f_req.attr, 324 &dev_attr_ds_req.attr, 325 &dev_attr_rd_sect.attr, 326 &dev_attr_wr_sect.attr, 327 NULL 328 }; 329 330 static struct attribute_group xen_vbdstat_group = { 331 .name = "statistics", 332 .attrs = xen_vbdstat_attrs, 333 }; 334 335 VBD_SHOW(physical_device, "%x:%x\n", be->major, be->minor); 336 VBD_SHOW(mode, "%s\n", be->mode); 337 338 static int xenvbd_sysfs_addif(struct xenbus_device *dev) 339 { 340 int error; 341 342 error = device_create_file(&dev->dev, &dev_attr_physical_device); 343 if (error) 344 goto fail1; 345 346 error = device_create_file(&dev->dev, &dev_attr_mode); 347 if (error) 348 goto fail2; 349 350 error = sysfs_create_group(&dev->dev.kobj, &xen_vbdstat_group); 351 if (error) 352 goto fail3; 353 354 return 0; 355 356 fail3: sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 357 fail2: device_remove_file(&dev->dev, &dev_attr_mode); 358 fail1: device_remove_file(&dev->dev, &dev_attr_physical_device); 359 return error; 360 } 361 362 static void xenvbd_sysfs_delif(struct xenbus_device *dev) 363 { 364 sysfs_remove_group(&dev->dev.kobj, &xen_vbdstat_group); 365 device_remove_file(&dev->dev, &dev_attr_mode); 366 device_remove_file(&dev->dev, &dev_attr_physical_device); 367 } 368 369 370 static void xen_vbd_free(struct xen_vbd *vbd) 371 { 372 if (vbd->bdev) 373 blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE); 374 vbd->bdev = NULL; 375 } 376 377 static int xen_vbd_create(struct xen_blkif *blkif, blkif_vdev_t handle, 378 unsigned major, unsigned minor, int readonly, 379 int cdrom) 380 { 381 struct xen_vbd *vbd; 382 struct block_device *bdev; 383 struct request_queue *q; 384 385 vbd = &blkif->vbd; 386 vbd->handle = handle; 387 vbd->readonly = readonly; 388 vbd->type = 0; 389 390 vbd->pdevice = MKDEV(major, minor); 391 392 bdev = blkdev_get_by_dev(vbd->pdevice, vbd->readonly ? 393 FMODE_READ : FMODE_WRITE, NULL); 394 395 if (IS_ERR(bdev)) { 396 pr_warn("xen_vbd_create: device %08x could not be opened\n", 397 vbd->pdevice); 398 return -ENOENT; 399 } 400 401 vbd->bdev = bdev; 402 if (vbd->bdev->bd_disk == NULL) { 403 pr_warn("xen_vbd_create: device %08x doesn't exist\n", 404 vbd->pdevice); 405 xen_vbd_free(vbd); 406 return -ENOENT; 407 } 408 vbd->size = vbd_sz(vbd); 409 410 if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom) 411 vbd->type |= VDISK_CDROM; 412 if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE) 413 vbd->type |= VDISK_REMOVABLE; 414 415 q = bdev_get_queue(bdev); 416 if (q && q->flush_flags) 417 vbd->flush_support = true; 418 419 if (q && blk_queue_secdiscard(q)) 420 vbd->discard_secure = true; 421 422 pr_debug("Successful creation of handle=%04x (dom=%u)\n", 423 handle, blkif->domid); 424 return 0; 425 } 426 static int xen_blkbk_remove(struct xenbus_device *dev) 427 { 428 struct backend_info *be = dev_get_drvdata(&dev->dev); 429 430 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 431 432 if (be->major || be->minor) 433 xenvbd_sysfs_delif(dev); 434 435 if (be->backend_watch.node) { 436 unregister_xenbus_watch(&be->backend_watch); 437 kfree(be->backend_watch.node); 438 be->backend_watch.node = NULL; 439 } 440 441 dev_set_drvdata(&dev->dev, NULL); 442 443 if (be->blkif) { 444 xen_blkif_disconnect(be->blkif); 445 xen_blkif_put(be->blkif); 446 } 447 448 kfree(be->mode); 449 kfree(be); 450 return 0; 451 } 452 453 int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt, 454 struct backend_info *be, int state) 455 { 456 struct xenbus_device *dev = be->dev; 457 int err; 458 459 err = xenbus_printf(xbt, dev->nodename, "feature-flush-cache", 460 "%d", state); 461 if (err) 462 dev_warn(&dev->dev, "writing feature-flush-cache (%d)", err); 463 464 return err; 465 } 466 467 static void xen_blkbk_discard(struct xenbus_transaction xbt, struct backend_info *be) 468 { 469 struct xenbus_device *dev = be->dev; 470 struct xen_blkif *blkif = be->blkif; 471 int err; 472 int state = 0, discard_enable; 473 struct block_device *bdev = be->blkif->vbd.bdev; 474 struct request_queue *q = bdev_get_queue(bdev); 475 476 err = xenbus_scanf(XBT_NIL, dev->nodename, "discard-enable", "%d", 477 &discard_enable); 478 if (err == 1 && !discard_enable) 479 return; 480 481 if (blk_queue_discard(q)) { 482 err = xenbus_printf(xbt, dev->nodename, 483 "discard-granularity", "%u", 484 q->limits.discard_granularity); 485 if (err) { 486 dev_warn(&dev->dev, "writing discard-granularity (%d)", err); 487 return; 488 } 489 err = xenbus_printf(xbt, dev->nodename, 490 "discard-alignment", "%u", 491 q->limits.discard_alignment); 492 if (err) { 493 dev_warn(&dev->dev, "writing discard-alignment (%d)", err); 494 return; 495 } 496 state = 1; 497 /* Optional. */ 498 err = xenbus_printf(xbt, dev->nodename, 499 "discard-secure", "%d", 500 blkif->vbd.discard_secure); 501 if (err) { 502 dev_warn(&dev->dev, "writing discard-secure (%d)", err); 503 return; 504 } 505 } 506 err = xenbus_printf(xbt, dev->nodename, "feature-discard", 507 "%d", state); 508 if (err) 509 dev_warn(&dev->dev, "writing feature-discard (%d)", err); 510 } 511 int xen_blkbk_barrier(struct xenbus_transaction xbt, 512 struct backend_info *be, int state) 513 { 514 struct xenbus_device *dev = be->dev; 515 int err; 516 517 err = xenbus_printf(xbt, dev->nodename, "feature-barrier", 518 "%d", state); 519 if (err) 520 dev_warn(&dev->dev, "writing feature-barrier (%d)", err); 521 522 return err; 523 } 524 525 /* 526 * Entry point to this code when a new device is created. Allocate the basic 527 * structures, and watch the store waiting for the hotplug scripts to tell us 528 * the device's physical major and minor numbers. Switch to InitWait. 529 */ 530 static int xen_blkbk_probe(struct xenbus_device *dev, 531 const struct xenbus_device_id *id) 532 { 533 int err; 534 struct backend_info *be = kzalloc(sizeof(struct backend_info), 535 GFP_KERNEL); 536 537 /* match the pr_debug in xen_blkbk_remove */ 538 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 539 540 if (!be) { 541 xenbus_dev_fatal(dev, -ENOMEM, 542 "allocating backend structure"); 543 return -ENOMEM; 544 } 545 be->dev = dev; 546 dev_set_drvdata(&dev->dev, be); 547 548 be->blkif = xen_blkif_alloc(dev->otherend_id); 549 if (IS_ERR(be->blkif)) { 550 err = PTR_ERR(be->blkif); 551 be->blkif = NULL; 552 xenbus_dev_fatal(dev, err, "creating block interface"); 553 goto fail; 554 } 555 556 /* setup back pointer */ 557 be->blkif->be = be; 558 559 err = xenbus_watch_pathfmt(dev, &be->backend_watch, backend_changed, 560 "%s/%s", dev->nodename, "physical-device"); 561 if (err) 562 goto fail; 563 564 err = xenbus_printf(XBT_NIL, dev->nodename, "max-ring-page-order", "%u", 565 xen_blkif_max_ring_order); 566 if (err) 567 pr_warn("%s write out 'max-ring-page-order' failed\n", __func__); 568 569 err = xenbus_switch_state(dev, XenbusStateInitWait); 570 if (err) 571 goto fail; 572 573 return 0; 574 575 fail: 576 pr_warn("%s failed\n", __func__); 577 xen_blkbk_remove(dev); 578 return err; 579 } 580 581 582 /* 583 * Callback received when the hotplug scripts have placed the physical-device 584 * node. Read it and the mode node, and create a vbd. If the frontend is 585 * ready, connect. 586 */ 587 static void backend_changed(struct xenbus_watch *watch, 588 const char **vec, unsigned int len) 589 { 590 int err; 591 unsigned major; 592 unsigned minor; 593 struct backend_info *be 594 = container_of(watch, struct backend_info, backend_watch); 595 struct xenbus_device *dev = be->dev; 596 int cdrom = 0; 597 unsigned long handle; 598 char *device_type; 599 600 pr_debug("%s %p %d\n", __func__, dev, dev->otherend_id); 601 602 err = xenbus_scanf(XBT_NIL, dev->nodename, "physical-device", "%x:%x", 603 &major, &minor); 604 if (XENBUS_EXIST_ERR(err)) { 605 /* 606 * Since this watch will fire once immediately after it is 607 * registered, we expect this. Ignore it, and wait for the 608 * hotplug scripts. 609 */ 610 return; 611 } 612 if (err != 2) { 613 xenbus_dev_fatal(dev, err, "reading physical-device"); 614 return; 615 } 616 617 if (be->major | be->minor) { 618 if (be->major != major || be->minor != minor) 619 pr_warn("changing physical device (from %x:%x to %x:%x) not supported.\n", 620 be->major, be->minor, major, minor); 621 return; 622 } 623 624 be->mode = xenbus_read(XBT_NIL, dev->nodename, "mode", NULL); 625 if (IS_ERR(be->mode)) { 626 err = PTR_ERR(be->mode); 627 be->mode = NULL; 628 xenbus_dev_fatal(dev, err, "reading mode"); 629 return; 630 } 631 632 device_type = xenbus_read(XBT_NIL, dev->otherend, "device-type", NULL); 633 if (!IS_ERR(device_type)) { 634 cdrom = strcmp(device_type, "cdrom") == 0; 635 kfree(device_type); 636 } 637 638 /* Front end dir is a number, which is used as the handle. */ 639 err = kstrtoul(strrchr(dev->otherend, '/') + 1, 0, &handle); 640 if (err) 641 return; 642 643 be->major = major; 644 be->minor = minor; 645 646 err = xen_vbd_create(be->blkif, handle, major, minor, 647 !strchr(be->mode, 'w'), cdrom); 648 649 if (err) 650 xenbus_dev_fatal(dev, err, "creating vbd structure"); 651 else { 652 err = xenvbd_sysfs_addif(dev); 653 if (err) { 654 xen_vbd_free(&be->blkif->vbd); 655 xenbus_dev_fatal(dev, err, "creating sysfs entries"); 656 } 657 } 658 659 if (err) { 660 kfree(be->mode); 661 be->mode = NULL; 662 be->major = 0; 663 be->minor = 0; 664 } else { 665 /* We're potentially connected now */ 666 xen_update_blkif_status(be->blkif); 667 } 668 } 669 670 671 /* 672 * Callback received when the frontend's state changes. 673 */ 674 static void frontend_changed(struct xenbus_device *dev, 675 enum xenbus_state frontend_state) 676 { 677 struct backend_info *be = dev_get_drvdata(&dev->dev); 678 int err; 679 680 pr_debug("%s %p %s\n", __func__, dev, xenbus_strstate(frontend_state)); 681 682 switch (frontend_state) { 683 case XenbusStateInitialising: 684 if (dev->state == XenbusStateClosed) { 685 pr_info("%s: prepare for reconnect\n", dev->nodename); 686 xenbus_switch_state(dev, XenbusStateInitWait); 687 } 688 break; 689 690 case XenbusStateInitialised: 691 case XenbusStateConnected: 692 /* 693 * Ensure we connect even when two watches fire in 694 * close succession and we miss the intermediate value 695 * of frontend_state. 696 */ 697 if (dev->state == XenbusStateConnected) 698 break; 699 700 /* 701 * Enforce precondition before potential leak point. 702 * xen_blkif_disconnect() is idempotent. 703 */ 704 err = xen_blkif_disconnect(be->blkif); 705 if (err) { 706 xenbus_dev_fatal(dev, err, "pending I/O"); 707 break; 708 } 709 710 err = connect_ring(be); 711 if (err) 712 break; 713 xen_update_blkif_status(be->blkif); 714 break; 715 716 case XenbusStateClosing: 717 xenbus_switch_state(dev, XenbusStateClosing); 718 break; 719 720 case XenbusStateClosed: 721 xen_blkif_disconnect(be->blkif); 722 xenbus_switch_state(dev, XenbusStateClosed); 723 if (xenbus_dev_is_online(dev)) 724 break; 725 /* fall through if not online */ 726 case XenbusStateUnknown: 727 /* implies xen_blkif_disconnect() via xen_blkbk_remove() */ 728 device_unregister(&dev->dev); 729 break; 730 731 default: 732 xenbus_dev_fatal(dev, -EINVAL, "saw state %d at frontend", 733 frontend_state); 734 break; 735 } 736 } 737 738 739 /* ** Connection ** */ 740 741 742 /* 743 * Write the physical details regarding the block device to the store, and 744 * switch to Connected state. 745 */ 746 static void connect(struct backend_info *be) 747 { 748 struct xenbus_transaction xbt; 749 int err; 750 struct xenbus_device *dev = be->dev; 751 752 pr_debug("%s %s\n", __func__, dev->otherend); 753 754 /* Supply the information about the device the frontend needs */ 755 again: 756 err = xenbus_transaction_start(&xbt); 757 if (err) { 758 xenbus_dev_fatal(dev, err, "starting transaction"); 759 return; 760 } 761 762 /* If we can't advertise it is OK. */ 763 xen_blkbk_flush_diskcache(xbt, be, be->blkif->vbd.flush_support); 764 765 xen_blkbk_discard(xbt, be); 766 767 xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support); 768 769 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1); 770 if (err) { 771 xenbus_dev_fatal(dev, err, "writing %s/feature-persistent", 772 dev->nodename); 773 goto abort; 774 } 775 err = xenbus_printf(xbt, dev->nodename, "feature-max-indirect-segments", "%u", 776 MAX_INDIRECT_SEGMENTS); 777 if (err) 778 dev_warn(&dev->dev, "writing %s/feature-max-indirect-segments (%d)", 779 dev->nodename, err); 780 781 err = xenbus_printf(xbt, dev->nodename, "sectors", "%llu", 782 (unsigned long long)vbd_sz(&be->blkif->vbd)); 783 if (err) { 784 xenbus_dev_fatal(dev, err, "writing %s/sectors", 785 dev->nodename); 786 goto abort; 787 } 788 789 /* FIXME: use a typename instead */ 790 err = xenbus_printf(xbt, dev->nodename, "info", "%u", 791 be->blkif->vbd.type | 792 (be->blkif->vbd.readonly ? VDISK_READONLY : 0)); 793 if (err) { 794 xenbus_dev_fatal(dev, err, "writing %s/info", 795 dev->nodename); 796 goto abort; 797 } 798 err = xenbus_printf(xbt, dev->nodename, "sector-size", "%lu", 799 (unsigned long) 800 bdev_logical_block_size(be->blkif->vbd.bdev)); 801 if (err) { 802 xenbus_dev_fatal(dev, err, "writing %s/sector-size", 803 dev->nodename); 804 goto abort; 805 } 806 err = xenbus_printf(xbt, dev->nodename, "physical-sector-size", "%u", 807 bdev_physical_block_size(be->blkif->vbd.bdev)); 808 if (err) 809 xenbus_dev_error(dev, err, "writing %s/physical-sector-size", 810 dev->nodename); 811 812 err = xenbus_transaction_end(xbt, 0); 813 if (err == -EAGAIN) 814 goto again; 815 if (err) 816 xenbus_dev_fatal(dev, err, "ending transaction"); 817 818 err = xenbus_switch_state(dev, XenbusStateConnected); 819 if (err) 820 xenbus_dev_fatal(dev, err, "%s: switching to Connected state", 821 dev->nodename); 822 823 return; 824 abort: 825 xenbus_transaction_end(xbt, 1); 826 } 827 828 829 static int connect_ring(struct backend_info *be) 830 { 831 struct xenbus_device *dev = be->dev; 832 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS]; 833 unsigned int evtchn, nr_grefs, ring_page_order; 834 unsigned int pers_grants; 835 char protocol[64] = ""; 836 struct pending_req *req, *n; 837 int err, i, j; 838 839 pr_debug("%s %s\n", __func__, dev->otherend); 840 841 err = xenbus_scanf(XBT_NIL, dev->otherend, "event-channel", "%u", 842 &evtchn); 843 if (err != 1) { 844 err = -EINVAL; 845 xenbus_dev_fatal(dev, err, "reading %s/event-channel", 846 dev->otherend); 847 return err; 848 } 849 pr_info("event-channel %u\n", evtchn); 850 851 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u", 852 &ring_page_order); 853 if (err != 1) { 854 err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-ref", 855 "%u", &ring_ref[0]); 856 if (err != 1) { 857 err = -EINVAL; 858 xenbus_dev_fatal(dev, err, "reading %s/ring-ref", 859 dev->otherend); 860 return err; 861 } 862 nr_grefs = 1; 863 pr_info("%s:using single page: ring-ref %d\n", dev->otherend, 864 ring_ref[0]); 865 } else { 866 unsigned int i; 867 868 if (ring_page_order > xen_blkif_max_ring_order) { 869 err = -EINVAL; 870 xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d", 871 dev->otherend, ring_page_order, 872 xen_blkif_max_ring_order); 873 return err; 874 } 875 876 nr_grefs = 1 << ring_page_order; 877 for (i = 0; i < nr_grefs; i++) { 878 char ring_ref_name[RINGREF_NAME_LEN]; 879 880 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 881 err = xenbus_scanf(XBT_NIL, dev->otherend, ring_ref_name, 882 "%u", &ring_ref[i]); 883 if (err != 1) { 884 err = -EINVAL; 885 xenbus_dev_fatal(dev, err, "reading %s/%s", 886 dev->otherend, ring_ref_name); 887 return err; 888 } 889 pr_info("ring-ref%u: %u\n", i, ring_ref[i]); 890 } 891 } 892 893 be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT; 894 err = xenbus_gather(XBT_NIL, dev->otherend, "protocol", 895 "%63s", protocol, NULL); 896 if (err) 897 strcpy(protocol, "unspecified, assuming default"); 898 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE)) 899 be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE; 900 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32)) 901 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32; 902 else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64)) 903 be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64; 904 else { 905 xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol); 906 return -1; 907 } 908 err = xenbus_gather(XBT_NIL, dev->otherend, 909 "feature-persistent", "%u", 910 &pers_grants, NULL); 911 if (err) 912 pers_grants = 0; 913 914 be->blkif->vbd.feature_gnt_persistent = pers_grants; 915 be->blkif->vbd.overflow_max_grants = 0; 916 be->blkif->nr_ring_pages = nr_grefs; 917 918 pr_info("ring-pages:%d, event-channel %d, protocol %d (%s) %s\n", 919 nr_grefs, evtchn, be->blkif->blk_protocol, protocol, 920 pers_grants ? "persistent grants" : ""); 921 922 for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) { 923 req = kzalloc(sizeof(*req), GFP_KERNEL); 924 if (!req) 925 goto fail; 926 list_add_tail(&req->free_list, &be->blkif->pending_free); 927 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) { 928 req->segments[j] = kzalloc(sizeof(*req->segments[0]), GFP_KERNEL); 929 if (!req->segments[j]) 930 goto fail; 931 } 932 for (j = 0; j < MAX_INDIRECT_PAGES; j++) { 933 req->indirect_pages[j] = kzalloc(sizeof(*req->indirect_pages[0]), 934 GFP_KERNEL); 935 if (!req->indirect_pages[j]) 936 goto fail; 937 } 938 } 939 940 /* Map the shared frame, irq etc. */ 941 err = xen_blkif_map(be->blkif, ring_ref, nr_grefs, evtchn); 942 if (err) { 943 xenbus_dev_fatal(dev, err, "mapping ring-ref port %u", evtchn); 944 return err; 945 } 946 947 return 0; 948 949 fail: 950 list_for_each_entry_safe(req, n, &be->blkif->pending_free, free_list) { 951 list_del(&req->free_list); 952 for (j = 0; j < MAX_INDIRECT_SEGMENTS; j++) { 953 if (!req->segments[j]) 954 break; 955 kfree(req->segments[j]); 956 } 957 for (j = 0; j < MAX_INDIRECT_PAGES; j++) { 958 if (!req->indirect_pages[j]) 959 break; 960 kfree(req->indirect_pages[j]); 961 } 962 kfree(req); 963 } 964 return -ENOMEM; 965 } 966 967 static const struct xenbus_device_id xen_blkbk_ids[] = { 968 { "vbd" }, 969 { "" } 970 }; 971 972 static struct xenbus_driver xen_blkbk_driver = { 973 .ids = xen_blkbk_ids, 974 .probe = xen_blkbk_probe, 975 .remove = xen_blkbk_remove, 976 .otherend_changed = frontend_changed 977 }; 978 979 int xen_blkif_xenbus_init(void) 980 { 981 return xenbus_register_backend(&xen_blkbk_driver); 982 } 983