1 /* 2 * blkfront.c 3 * 4 * XenLinux virtual block device driver. 5 * 6 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand 7 * Modifications by Mark A. Williamson are (c) Intel Research Cambridge 8 * Copyright (c) 2004, Christian Limpach 9 * Copyright (c) 2004, Andrew Warfield 10 * Copyright (c) 2005, Christopher Clark 11 * Copyright (c) 2005, XenSource Ltd 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License version 2 15 * as published by the Free Software Foundation; or, when distributed 16 * separately from the Linux kernel or incorporated into other 17 * software packages, subject to the following license: 18 * 19 * Permission is hereby granted, free of charge, to any person obtaining a copy 20 * of this source file (the "Software"), to deal in the Software without 21 * restriction, including without limitation the rights to use, copy, modify, 22 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 23 * and to permit persons to whom the Software is furnished to do so, subject to 24 * the following conditions: 25 * 26 * The above copyright notice and this permission notice shall be included in 27 * all copies or substantial portions of the Software. 28 * 29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 30 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 32 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 33 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 34 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 35 * IN THE SOFTWARE. 36 */ 37 38 #include <linux/interrupt.h> 39 #include <linux/blkdev.h> 40 #include <linux/hdreg.h> 41 #include <linux/cdrom.h> 42 #include <linux/module.h> 43 #include <linux/slab.h> 44 #include <linux/mutex.h> 45 #include <linux/scatterlist.h> 46 47 #include <xen/xen.h> 48 #include <xen/xenbus.h> 49 #include <xen/grant_table.h> 50 #include <xen/events.h> 51 #include <xen/page.h> 52 #include <xen/platform_pci.h> 53 54 #include <xen/interface/grant_table.h> 55 #include <xen/interface/io/blkif.h> 56 #include <xen/interface/io/protocols.h> 57 58 #include <asm/xen/hypervisor.h> 59 60 enum blkif_state { 61 BLKIF_STATE_DISCONNECTED, 62 BLKIF_STATE_CONNECTED, 63 BLKIF_STATE_SUSPENDED, 64 }; 65 66 struct blk_shadow { 67 struct blkif_request req; 68 struct request *request; 69 unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 70 }; 71 72 static DEFINE_MUTEX(blkfront_mutex); 73 static const struct block_device_operations xlvbd_block_fops; 74 75 #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) 76 77 /* 78 * We have one of these per vbd, whether ide, scsi or 'other'. They 79 * hang in private_data off the gendisk structure. We may end up 80 * putting all kinds of interesting stuff here :-) 81 */ 82 struct blkfront_info 83 { 84 struct mutex mutex; 85 struct xenbus_device *xbdev; 86 struct gendisk *gd; 87 int vdevice; 88 blkif_vdev_t handle; 89 enum blkif_state connected; 90 int ring_ref; 91 struct blkif_front_ring ring; 92 struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 93 unsigned int evtchn, irq; 94 struct request_queue *rq; 95 struct work_struct work; 96 struct gnttab_free_callback callback; 97 struct blk_shadow shadow[BLK_RING_SIZE]; 98 unsigned long shadow_free; 99 unsigned int feature_flush; 100 unsigned int flush_op; 101 int is_ready; 102 }; 103 104 static DEFINE_SPINLOCK(blkif_io_lock); 105 106 static unsigned int nr_minors; 107 static unsigned long *minors; 108 static DEFINE_SPINLOCK(minor_lock); 109 110 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \ 111 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE) 112 #define GRANT_INVALID_REF 0 113 114 #define PARTS_PER_DISK 16 115 #define PARTS_PER_EXT_DISK 256 116 117 #define BLKIF_MAJOR(dev) ((dev)>>8) 118 #define BLKIF_MINOR(dev) ((dev) & 0xff) 119 120 #define EXT_SHIFT 28 121 #define EXTENDED (1<<EXT_SHIFT) 122 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 123 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 124 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 125 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 126 #define EMULATED_SD_DISK_MINOR_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET + (4 * 16)) 127 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_HD_DISK_NAME_OFFSET + 4) 128 129 #define DEV_NAME "xvd" /* name in /dev */ 130 131 static int get_id_from_freelist(struct blkfront_info *info) 132 { 133 unsigned long free = info->shadow_free; 134 BUG_ON(free >= BLK_RING_SIZE); 135 info->shadow_free = info->shadow[free].req.id; 136 info->shadow[free].req.id = 0x0fffffee; /* debug */ 137 return free; 138 } 139 140 static void add_id_to_freelist(struct blkfront_info *info, 141 unsigned long id) 142 { 143 info->shadow[id].req.id = info->shadow_free; 144 info->shadow[id].request = NULL; 145 info->shadow_free = id; 146 } 147 148 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 149 { 150 unsigned int end = minor + nr; 151 int rc; 152 153 if (end > nr_minors) { 154 unsigned long *bitmap, *old; 155 156 bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap), 157 GFP_KERNEL); 158 if (bitmap == NULL) 159 return -ENOMEM; 160 161 spin_lock(&minor_lock); 162 if (end > nr_minors) { 163 old = minors; 164 memcpy(bitmap, minors, 165 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 166 minors = bitmap; 167 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 168 } else 169 old = bitmap; 170 spin_unlock(&minor_lock); 171 kfree(old); 172 } 173 174 spin_lock(&minor_lock); 175 if (find_next_bit(minors, end, minor) >= end) { 176 for (; minor < end; ++minor) 177 __set_bit(minor, minors); 178 rc = 0; 179 } else 180 rc = -EBUSY; 181 spin_unlock(&minor_lock); 182 183 return rc; 184 } 185 186 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 187 { 188 unsigned int end = minor + nr; 189 190 BUG_ON(end > nr_minors); 191 spin_lock(&minor_lock); 192 for (; minor < end; ++minor) 193 __clear_bit(minor, minors); 194 spin_unlock(&minor_lock); 195 } 196 197 static void blkif_restart_queue_callback(void *arg) 198 { 199 struct blkfront_info *info = (struct blkfront_info *)arg; 200 schedule_work(&info->work); 201 } 202 203 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 204 { 205 /* We don't have real geometry info, but let's at least return 206 values consistent with the size of the device */ 207 sector_t nsect = get_capacity(bd->bd_disk); 208 sector_t cylinders = nsect; 209 210 hg->heads = 0xff; 211 hg->sectors = 0x3f; 212 sector_div(cylinders, hg->heads * hg->sectors); 213 hg->cylinders = cylinders; 214 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 215 hg->cylinders = 0xffff; 216 return 0; 217 } 218 219 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 220 unsigned command, unsigned long argument) 221 { 222 struct blkfront_info *info = bdev->bd_disk->private_data; 223 int i; 224 225 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 226 command, (long)argument); 227 228 switch (command) { 229 case CDROMMULTISESSION: 230 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 231 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 232 if (put_user(0, (char __user *)(argument + i))) 233 return -EFAULT; 234 return 0; 235 236 case CDROM_GET_CAPABILITY: { 237 struct gendisk *gd = info->gd; 238 if (gd->flags & GENHD_FL_CD) 239 return 0; 240 return -EINVAL; 241 } 242 243 default: 244 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 245 command);*/ 246 return -EINVAL; /* same return as native Linux */ 247 } 248 249 return 0; 250 } 251 252 /* 253 * Generate a Xen blkfront IO request from a blk layer request. Reads 254 * and writes are handled as expected. 255 * 256 * @req: a request struct 257 */ 258 static int blkif_queue_request(struct request *req) 259 { 260 struct blkfront_info *info = req->rq_disk->private_data; 261 unsigned long buffer_mfn; 262 struct blkif_request *ring_req; 263 unsigned long id; 264 unsigned int fsect, lsect; 265 int i, ref; 266 grant_ref_t gref_head; 267 struct scatterlist *sg; 268 269 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 270 return 1; 271 272 if (gnttab_alloc_grant_references( 273 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) { 274 gnttab_request_free_callback( 275 &info->callback, 276 blkif_restart_queue_callback, 277 info, 278 BLKIF_MAX_SEGMENTS_PER_REQUEST); 279 return 1; 280 } 281 282 /* Fill out a communications ring structure. */ 283 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); 284 id = get_id_from_freelist(info); 285 info->shadow[id].request = req; 286 287 ring_req->id = id; 288 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 289 ring_req->handle = info->handle; 290 291 ring_req->operation = rq_data_dir(req) ? 292 BLKIF_OP_WRITE : BLKIF_OP_READ; 293 294 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { 295 /* 296 * Ideally we can do an unordered flush-to-disk. In case the 297 * backend onlysupports barriers, use that. A barrier request 298 * a superset of FUA, so we can implement it the same 299 * way. (It's also a FLUSH+FUA, since it is 300 * guaranteed ordered WRT previous writes.) 301 */ 302 ring_req->operation = info->flush_op; 303 } 304 305 ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg); 306 BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST); 307 308 for_each_sg(info->sg, sg, ring_req->nr_segments, i) { 309 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg))); 310 fsect = sg->offset >> 9; 311 lsect = fsect + (sg->length >> 9) - 1; 312 /* install a grant reference. */ 313 ref = gnttab_claim_grant_reference(&gref_head); 314 BUG_ON(ref == -ENOSPC); 315 316 gnttab_grant_foreign_access_ref( 317 ref, 318 info->xbdev->otherend_id, 319 buffer_mfn, 320 rq_data_dir(req) ); 321 322 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn); 323 ring_req->u.rw.seg[i] = 324 (struct blkif_request_segment) { 325 .gref = ref, 326 .first_sect = fsect, 327 .last_sect = lsect }; 328 } 329 330 info->ring.req_prod_pvt++; 331 332 /* Keep a private copy so we can reissue requests when recovering. */ 333 info->shadow[id].req = *ring_req; 334 335 gnttab_free_grant_references(gref_head); 336 337 return 0; 338 } 339 340 341 static inline void flush_requests(struct blkfront_info *info) 342 { 343 int notify; 344 345 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); 346 347 if (notify) 348 notify_remote_via_irq(info->irq); 349 } 350 351 /* 352 * do_blkif_request 353 * read a block; request is in a request queue 354 */ 355 static void do_blkif_request(struct request_queue *rq) 356 { 357 struct blkfront_info *info = NULL; 358 struct request *req; 359 int queued; 360 361 pr_debug("Entered do_blkif_request\n"); 362 363 queued = 0; 364 365 while ((req = blk_peek_request(rq)) != NULL) { 366 info = req->rq_disk->private_data; 367 368 if (RING_FULL(&info->ring)) 369 goto wait; 370 371 blk_start_request(req); 372 373 if (req->cmd_type != REQ_TYPE_FS) { 374 __blk_end_request_all(req, -EIO); 375 continue; 376 } 377 378 pr_debug("do_blk_req %p: cmd %p, sec %lx, " 379 "(%u/%u) buffer:%p [%s]\n", 380 req, req->cmd, (unsigned long)blk_rq_pos(req), 381 blk_rq_cur_sectors(req), blk_rq_sectors(req), 382 req->buffer, rq_data_dir(req) ? "write" : "read"); 383 384 if (blkif_queue_request(req)) { 385 blk_requeue_request(rq, req); 386 wait: 387 /* Avoid pointless unplugs. */ 388 blk_stop_queue(rq); 389 break; 390 } 391 392 queued++; 393 } 394 395 if (queued != 0) 396 flush_requests(info); 397 } 398 399 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size) 400 { 401 struct request_queue *rq; 402 403 rq = blk_init_queue(do_blkif_request, &blkif_io_lock); 404 if (rq == NULL) 405 return -1; 406 407 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 408 409 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 410 blk_queue_logical_block_size(rq, sector_size); 411 blk_queue_max_hw_sectors(rq, 512); 412 413 /* Each segment in a request is up to an aligned page in size. */ 414 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 415 blk_queue_max_segment_size(rq, PAGE_SIZE); 416 417 /* Ensure a merged request will fit in a single I/O ring slot. */ 418 blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); 419 420 /* Make sure buffer addresses are sector-aligned. */ 421 blk_queue_dma_alignment(rq, 511); 422 423 /* Make sure we don't use bounce buffers. */ 424 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); 425 426 gd->queue = rq; 427 428 return 0; 429 } 430 431 432 static void xlvbd_flush(struct blkfront_info *info) 433 { 434 blk_queue_flush(info->rq, info->feature_flush); 435 printk(KERN_INFO "blkfront: %s: %s: %s\n", 436 info->gd->disk_name, 437 info->flush_op == BLKIF_OP_WRITE_BARRIER ? 438 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ? 439 "flush diskcache" : "barrier or flush"), 440 info->feature_flush ? "enabled" : "disabled"); 441 } 442 443 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 444 { 445 int major; 446 major = BLKIF_MAJOR(vdevice); 447 *minor = BLKIF_MINOR(vdevice); 448 switch (major) { 449 case XEN_IDE0_MAJOR: 450 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 451 *minor = ((*minor / 64) * PARTS_PER_DISK) + 452 EMULATED_HD_DISK_MINOR_OFFSET; 453 break; 454 case XEN_IDE1_MAJOR: 455 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 456 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 457 EMULATED_HD_DISK_MINOR_OFFSET; 458 break; 459 case XEN_SCSI_DISK0_MAJOR: 460 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 461 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 462 break; 463 case XEN_SCSI_DISK1_MAJOR: 464 case XEN_SCSI_DISK2_MAJOR: 465 case XEN_SCSI_DISK3_MAJOR: 466 case XEN_SCSI_DISK4_MAJOR: 467 case XEN_SCSI_DISK5_MAJOR: 468 case XEN_SCSI_DISK6_MAJOR: 469 case XEN_SCSI_DISK7_MAJOR: 470 *offset = (*minor / PARTS_PER_DISK) + 471 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 472 EMULATED_SD_DISK_NAME_OFFSET; 473 *minor = *minor + 474 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 475 EMULATED_SD_DISK_MINOR_OFFSET; 476 break; 477 case XEN_SCSI_DISK8_MAJOR: 478 case XEN_SCSI_DISK9_MAJOR: 479 case XEN_SCSI_DISK10_MAJOR: 480 case XEN_SCSI_DISK11_MAJOR: 481 case XEN_SCSI_DISK12_MAJOR: 482 case XEN_SCSI_DISK13_MAJOR: 483 case XEN_SCSI_DISK14_MAJOR: 484 case XEN_SCSI_DISK15_MAJOR: 485 *offset = (*minor / PARTS_PER_DISK) + 486 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 487 EMULATED_SD_DISK_NAME_OFFSET; 488 *minor = *minor + 489 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 490 EMULATED_SD_DISK_MINOR_OFFSET; 491 break; 492 case XENVBD_MAJOR: 493 *offset = *minor / PARTS_PER_DISK; 494 break; 495 default: 496 printk(KERN_WARNING "blkfront: your disk configuration is " 497 "incorrect, please use an xvd device instead\n"); 498 return -ENODEV; 499 } 500 return 0; 501 } 502 503 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 504 struct blkfront_info *info, 505 u16 vdisk_info, u16 sector_size) 506 { 507 struct gendisk *gd; 508 int nr_minors = 1; 509 int err; 510 unsigned int offset; 511 int minor; 512 int nr_parts; 513 514 BUG_ON(info->gd != NULL); 515 BUG_ON(info->rq != NULL); 516 517 if ((info->vdevice>>EXT_SHIFT) > 1) { 518 /* this is above the extended range; something is wrong */ 519 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 520 return -ENODEV; 521 } 522 523 if (!VDEV_IS_EXTENDED(info->vdevice)) { 524 err = xen_translate_vdev(info->vdevice, &minor, &offset); 525 if (err) 526 return err; 527 nr_parts = PARTS_PER_DISK; 528 } else { 529 minor = BLKIF_MINOR_EXT(info->vdevice); 530 nr_parts = PARTS_PER_EXT_DISK; 531 offset = minor / nr_parts; 532 if (xen_hvm_domain() && offset <= EMULATED_HD_DISK_NAME_OFFSET + 4) 533 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 534 "emulated IDE disks,\n\t choose an xvd device name" 535 "from xvde on\n", info->vdevice); 536 } 537 err = -ENODEV; 538 539 if ((minor % nr_parts) == 0) 540 nr_minors = nr_parts; 541 542 err = xlbd_reserve_minors(minor, nr_minors); 543 if (err) 544 goto out; 545 err = -ENODEV; 546 547 gd = alloc_disk(nr_minors); 548 if (gd == NULL) 549 goto release; 550 551 if (nr_minors > 1) { 552 if (offset < 26) 553 sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset); 554 else 555 sprintf(gd->disk_name, "%s%c%c", DEV_NAME, 556 'a' + ((offset / 26)-1), 'a' + (offset % 26)); 557 } else { 558 if (offset < 26) 559 sprintf(gd->disk_name, "%s%c%d", DEV_NAME, 560 'a' + offset, 561 minor & (nr_parts - 1)); 562 else 563 sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME, 564 'a' + ((offset / 26) - 1), 565 'a' + (offset % 26), 566 minor & (nr_parts - 1)); 567 } 568 569 gd->major = XENVBD_MAJOR; 570 gd->first_minor = minor; 571 gd->fops = &xlvbd_block_fops; 572 gd->private_data = info; 573 gd->driverfs_dev = &(info->xbdev->dev); 574 set_capacity(gd, capacity); 575 576 if (xlvbd_init_blk_queue(gd, sector_size)) { 577 del_gendisk(gd); 578 goto release; 579 } 580 581 info->rq = gd->queue; 582 info->gd = gd; 583 584 xlvbd_flush(info); 585 586 if (vdisk_info & VDISK_READONLY) 587 set_disk_ro(gd, 1); 588 589 if (vdisk_info & VDISK_REMOVABLE) 590 gd->flags |= GENHD_FL_REMOVABLE; 591 592 if (vdisk_info & VDISK_CDROM) 593 gd->flags |= GENHD_FL_CD; 594 595 return 0; 596 597 release: 598 xlbd_release_minors(minor, nr_minors); 599 out: 600 return err; 601 } 602 603 static void xlvbd_release_gendisk(struct blkfront_info *info) 604 { 605 unsigned int minor, nr_minors; 606 unsigned long flags; 607 608 if (info->rq == NULL) 609 return; 610 611 spin_lock_irqsave(&blkif_io_lock, flags); 612 613 /* No more blkif_request(). */ 614 blk_stop_queue(info->rq); 615 616 /* No more gnttab callback work. */ 617 gnttab_cancel_free_callback(&info->callback); 618 spin_unlock_irqrestore(&blkif_io_lock, flags); 619 620 /* Flush gnttab callback work. Must be done with no locks held. */ 621 flush_work_sync(&info->work); 622 623 del_gendisk(info->gd); 624 625 minor = info->gd->first_minor; 626 nr_minors = info->gd->minors; 627 xlbd_release_minors(minor, nr_minors); 628 629 blk_cleanup_queue(info->rq); 630 info->rq = NULL; 631 632 put_disk(info->gd); 633 info->gd = NULL; 634 } 635 636 static void kick_pending_request_queues(struct blkfront_info *info) 637 { 638 if (!RING_FULL(&info->ring)) { 639 /* Re-enable calldowns. */ 640 blk_start_queue(info->rq); 641 /* Kick things off immediately. */ 642 do_blkif_request(info->rq); 643 } 644 } 645 646 static void blkif_restart_queue(struct work_struct *work) 647 { 648 struct blkfront_info *info = container_of(work, struct blkfront_info, work); 649 650 spin_lock_irq(&blkif_io_lock); 651 if (info->connected == BLKIF_STATE_CONNECTED) 652 kick_pending_request_queues(info); 653 spin_unlock_irq(&blkif_io_lock); 654 } 655 656 static void blkif_free(struct blkfront_info *info, int suspend) 657 { 658 /* Prevent new requests being issued until we fix things up. */ 659 spin_lock_irq(&blkif_io_lock); 660 info->connected = suspend ? 661 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 662 /* No more blkif_request(). */ 663 if (info->rq) 664 blk_stop_queue(info->rq); 665 /* No more gnttab callback work. */ 666 gnttab_cancel_free_callback(&info->callback); 667 spin_unlock_irq(&blkif_io_lock); 668 669 /* Flush gnttab callback work. Must be done with no locks held. */ 670 flush_work_sync(&info->work); 671 672 /* Free resources associated with old device channel. */ 673 if (info->ring_ref != GRANT_INVALID_REF) { 674 gnttab_end_foreign_access(info->ring_ref, 0, 675 (unsigned long)info->ring.sring); 676 info->ring_ref = GRANT_INVALID_REF; 677 info->ring.sring = NULL; 678 } 679 if (info->irq) 680 unbind_from_irqhandler(info->irq, info); 681 info->evtchn = info->irq = 0; 682 683 } 684 685 static void blkif_completion(struct blk_shadow *s) 686 { 687 int i; 688 for (i = 0; i < s->req.nr_segments; i++) 689 gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL); 690 } 691 692 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 693 { 694 struct request *req; 695 struct blkif_response *bret; 696 RING_IDX i, rp; 697 unsigned long flags; 698 struct blkfront_info *info = (struct blkfront_info *)dev_id; 699 int error; 700 701 spin_lock_irqsave(&blkif_io_lock, flags); 702 703 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { 704 spin_unlock_irqrestore(&blkif_io_lock, flags); 705 return IRQ_HANDLED; 706 } 707 708 again: 709 rp = info->ring.sring->rsp_prod; 710 rmb(); /* Ensure we see queued responses up to 'rp'. */ 711 712 for (i = info->ring.rsp_cons; i != rp; i++) { 713 unsigned long id; 714 715 bret = RING_GET_RESPONSE(&info->ring, i); 716 id = bret->id; 717 req = info->shadow[id].request; 718 719 blkif_completion(&info->shadow[id]); 720 721 add_id_to_freelist(info, id); 722 723 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; 724 switch (bret->operation) { 725 case BLKIF_OP_FLUSH_DISKCACHE: 726 case BLKIF_OP_WRITE_BARRIER: 727 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 728 printk(KERN_WARNING "blkfront: %s: write %s op failed\n", 729 info->flush_op == BLKIF_OP_WRITE_BARRIER ? 730 "barrier" : "flush disk cache", 731 info->gd->disk_name); 732 error = -EOPNOTSUPP; 733 } 734 if (unlikely(bret->status == BLKIF_RSP_ERROR && 735 info->shadow[id].req.nr_segments == 0)) { 736 printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n", 737 info->flush_op == BLKIF_OP_WRITE_BARRIER ? 738 "barrier" : "flush disk cache", 739 info->gd->disk_name); 740 error = -EOPNOTSUPP; 741 } 742 if (unlikely(error)) { 743 if (error == -EOPNOTSUPP) 744 error = 0; 745 info->feature_flush = 0; 746 info->flush_op = 0; 747 xlvbd_flush(info); 748 } 749 /* fall through */ 750 case BLKIF_OP_READ: 751 case BLKIF_OP_WRITE: 752 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 753 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 754 "request: %x\n", bret->status); 755 756 __blk_end_request_all(req, error); 757 break; 758 default: 759 BUG(); 760 } 761 } 762 763 info->ring.rsp_cons = i; 764 765 if (i != info->ring.req_prod_pvt) { 766 int more_to_do; 767 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 768 if (more_to_do) 769 goto again; 770 } else 771 info->ring.sring->rsp_event = i + 1; 772 773 kick_pending_request_queues(info); 774 775 spin_unlock_irqrestore(&blkif_io_lock, flags); 776 777 return IRQ_HANDLED; 778 } 779 780 781 static int setup_blkring(struct xenbus_device *dev, 782 struct blkfront_info *info) 783 { 784 struct blkif_sring *sring; 785 int err; 786 787 info->ring_ref = GRANT_INVALID_REF; 788 789 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH); 790 if (!sring) { 791 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 792 return -ENOMEM; 793 } 794 SHARED_RING_INIT(sring); 795 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 796 797 sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST); 798 799 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); 800 if (err < 0) { 801 free_page((unsigned long)sring); 802 info->ring.sring = NULL; 803 goto fail; 804 } 805 info->ring_ref = err; 806 807 err = xenbus_alloc_evtchn(dev, &info->evtchn); 808 if (err) 809 goto fail; 810 811 err = bind_evtchn_to_irqhandler(info->evtchn, 812 blkif_interrupt, 813 IRQF_SAMPLE_RANDOM, "blkif", info); 814 if (err <= 0) { 815 xenbus_dev_fatal(dev, err, 816 "bind_evtchn_to_irqhandler failed"); 817 goto fail; 818 } 819 info->irq = err; 820 821 return 0; 822 fail: 823 blkif_free(info, 0); 824 return err; 825 } 826 827 828 /* Common code used when first setting up, and when resuming. */ 829 static int talk_to_blkback(struct xenbus_device *dev, 830 struct blkfront_info *info) 831 { 832 const char *message = NULL; 833 struct xenbus_transaction xbt; 834 int err; 835 836 /* Create shared ring, alloc event channel. */ 837 err = setup_blkring(dev, info); 838 if (err) 839 goto out; 840 841 again: 842 err = xenbus_transaction_start(&xbt); 843 if (err) { 844 xenbus_dev_fatal(dev, err, "starting transaction"); 845 goto destroy_blkring; 846 } 847 848 err = xenbus_printf(xbt, dev->nodename, 849 "ring-ref", "%u", info->ring_ref); 850 if (err) { 851 message = "writing ring-ref"; 852 goto abort_transaction; 853 } 854 err = xenbus_printf(xbt, dev->nodename, 855 "event-channel", "%u", info->evtchn); 856 if (err) { 857 message = "writing event-channel"; 858 goto abort_transaction; 859 } 860 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 861 XEN_IO_PROTO_ABI_NATIVE); 862 if (err) { 863 message = "writing protocol"; 864 goto abort_transaction; 865 } 866 867 err = xenbus_transaction_end(xbt, 0); 868 if (err) { 869 if (err == -EAGAIN) 870 goto again; 871 xenbus_dev_fatal(dev, err, "completing transaction"); 872 goto destroy_blkring; 873 } 874 875 xenbus_switch_state(dev, XenbusStateInitialised); 876 877 return 0; 878 879 abort_transaction: 880 xenbus_transaction_end(xbt, 1); 881 if (message) 882 xenbus_dev_fatal(dev, err, "%s", message); 883 destroy_blkring: 884 blkif_free(info, 0); 885 out: 886 return err; 887 } 888 889 /** 890 * Entry point to this code when a new device is created. Allocate the basic 891 * structures and the ring buffer for communication with the backend, and 892 * inform the backend of the appropriate details for those. Switch to 893 * Initialised state. 894 */ 895 static int blkfront_probe(struct xenbus_device *dev, 896 const struct xenbus_device_id *id) 897 { 898 int err, vdevice, i; 899 struct blkfront_info *info; 900 901 /* FIXME: Use dynamic device id if this is not set. */ 902 err = xenbus_scanf(XBT_NIL, dev->nodename, 903 "virtual-device", "%i", &vdevice); 904 if (err != 1) { 905 /* go looking in the extended area instead */ 906 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 907 "%i", &vdevice); 908 if (err != 1) { 909 xenbus_dev_fatal(dev, err, "reading virtual-device"); 910 return err; 911 } 912 } 913 914 if (xen_hvm_domain()) { 915 char *type; 916 int len; 917 /* no unplug has been done: do not hook devices != xen vbds */ 918 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) { 919 int major; 920 921 if (!VDEV_IS_EXTENDED(vdevice)) 922 major = BLKIF_MAJOR(vdevice); 923 else 924 major = XENVBD_MAJOR; 925 926 if (major != XENVBD_MAJOR) { 927 printk(KERN_INFO 928 "%s: HVM does not support vbd %d as xen block device\n", 929 __FUNCTION__, vdevice); 930 return -ENODEV; 931 } 932 } 933 /* do not create a PV cdrom device if we are an HVM guest */ 934 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 935 if (IS_ERR(type)) 936 return -ENODEV; 937 if (strncmp(type, "cdrom", 5) == 0) { 938 kfree(type); 939 return -ENODEV; 940 } 941 kfree(type); 942 } 943 info = kzalloc(sizeof(*info), GFP_KERNEL); 944 if (!info) { 945 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 946 return -ENOMEM; 947 } 948 949 mutex_init(&info->mutex); 950 info->xbdev = dev; 951 info->vdevice = vdevice; 952 info->connected = BLKIF_STATE_DISCONNECTED; 953 INIT_WORK(&info->work, blkif_restart_queue); 954 955 for (i = 0; i < BLK_RING_SIZE; i++) 956 info->shadow[i].req.id = i+1; 957 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff; 958 959 /* Front end dir is a number, which is used as the id. */ 960 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 961 dev_set_drvdata(&dev->dev, info); 962 963 err = talk_to_blkback(dev, info); 964 if (err) { 965 kfree(info); 966 dev_set_drvdata(&dev->dev, NULL); 967 return err; 968 } 969 970 return 0; 971 } 972 973 974 static int blkif_recover(struct blkfront_info *info) 975 { 976 int i; 977 struct blkif_request *req; 978 struct blk_shadow *copy; 979 int j; 980 981 /* Stage 1: Make a safe copy of the shadow state. */ 982 copy = kmalloc(sizeof(info->shadow), 983 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); 984 if (!copy) 985 return -ENOMEM; 986 memcpy(copy, info->shadow, sizeof(info->shadow)); 987 988 /* Stage 2: Set up free list. */ 989 memset(&info->shadow, 0, sizeof(info->shadow)); 990 for (i = 0; i < BLK_RING_SIZE; i++) 991 info->shadow[i].req.id = i+1; 992 info->shadow_free = info->ring.req_prod_pvt; 993 info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff; 994 995 /* Stage 3: Find pending requests and requeue them. */ 996 for (i = 0; i < BLK_RING_SIZE; i++) { 997 /* Not in use? */ 998 if (!copy[i].request) 999 continue; 1000 1001 /* Grab a request slot and copy shadow state into it. */ 1002 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); 1003 *req = copy[i].req; 1004 1005 /* We get a new request id, and must reset the shadow state. */ 1006 req->id = get_id_from_freelist(info); 1007 memcpy(&info->shadow[req->id], ©[i], sizeof(copy[i])); 1008 1009 /* Rewrite any grant references invalidated by susp/resume. */ 1010 for (j = 0; j < req->nr_segments; j++) 1011 gnttab_grant_foreign_access_ref( 1012 req->u.rw.seg[j].gref, 1013 info->xbdev->otherend_id, 1014 pfn_to_mfn(info->shadow[req->id].frame[j]), 1015 rq_data_dir(info->shadow[req->id].request)); 1016 info->shadow[req->id].req = *req; 1017 1018 info->ring.req_prod_pvt++; 1019 } 1020 1021 kfree(copy); 1022 1023 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1024 1025 spin_lock_irq(&blkif_io_lock); 1026 1027 /* Now safe for us to use the shared ring */ 1028 info->connected = BLKIF_STATE_CONNECTED; 1029 1030 /* Send off requeued requests */ 1031 flush_requests(info); 1032 1033 /* Kick any other new requests queued since we resumed */ 1034 kick_pending_request_queues(info); 1035 1036 spin_unlock_irq(&blkif_io_lock); 1037 1038 return 0; 1039 } 1040 1041 /** 1042 * We are reconnecting to the backend, due to a suspend/resume, or a backend 1043 * driver restart. We tear down our blkif structure and recreate it, but 1044 * leave the device-layer structures intact so that this is transparent to the 1045 * rest of the kernel. 1046 */ 1047 static int blkfront_resume(struct xenbus_device *dev) 1048 { 1049 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1050 int err; 1051 1052 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 1053 1054 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 1055 1056 err = talk_to_blkback(dev, info); 1057 if (info->connected == BLKIF_STATE_SUSPENDED && !err) 1058 err = blkif_recover(info); 1059 1060 return err; 1061 } 1062 1063 static void 1064 blkfront_closing(struct blkfront_info *info) 1065 { 1066 struct xenbus_device *xbdev = info->xbdev; 1067 struct block_device *bdev = NULL; 1068 1069 mutex_lock(&info->mutex); 1070 1071 if (xbdev->state == XenbusStateClosing) { 1072 mutex_unlock(&info->mutex); 1073 return; 1074 } 1075 1076 if (info->gd) 1077 bdev = bdget_disk(info->gd, 0); 1078 1079 mutex_unlock(&info->mutex); 1080 1081 if (!bdev) { 1082 xenbus_frontend_closed(xbdev); 1083 return; 1084 } 1085 1086 mutex_lock(&bdev->bd_mutex); 1087 1088 if (bdev->bd_openers) { 1089 xenbus_dev_error(xbdev, -EBUSY, 1090 "Device in use; refusing to close"); 1091 xenbus_switch_state(xbdev, XenbusStateClosing); 1092 } else { 1093 xlvbd_release_gendisk(info); 1094 xenbus_frontend_closed(xbdev); 1095 } 1096 1097 mutex_unlock(&bdev->bd_mutex); 1098 bdput(bdev); 1099 } 1100 1101 /* 1102 * Invoked when the backend is finally 'ready' (and has told produced 1103 * the details about the physical device - #sectors, size, etc). 1104 */ 1105 static void blkfront_connect(struct blkfront_info *info) 1106 { 1107 unsigned long long sectors; 1108 unsigned long sector_size; 1109 unsigned int binfo; 1110 int err; 1111 int barrier, flush; 1112 1113 switch (info->connected) { 1114 case BLKIF_STATE_CONNECTED: 1115 /* 1116 * Potentially, the back-end may be signalling 1117 * a capacity change; update the capacity. 1118 */ 1119 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1120 "sectors", "%Lu", §ors); 1121 if (XENBUS_EXIST_ERR(err)) 1122 return; 1123 printk(KERN_INFO "Setting capacity to %Lu\n", 1124 sectors); 1125 set_capacity(info->gd, sectors); 1126 revalidate_disk(info->gd); 1127 1128 /* fall through */ 1129 case BLKIF_STATE_SUSPENDED: 1130 return; 1131 1132 default: 1133 break; 1134 } 1135 1136 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 1137 __func__, info->xbdev->otherend); 1138 1139 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1140 "sectors", "%llu", §ors, 1141 "info", "%u", &binfo, 1142 "sector-size", "%lu", §or_size, 1143 NULL); 1144 if (err) { 1145 xenbus_dev_fatal(info->xbdev, err, 1146 "reading backend fields at %s", 1147 info->xbdev->otherend); 1148 return; 1149 } 1150 1151 info->feature_flush = 0; 1152 info->flush_op = 0; 1153 1154 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1155 "feature-barrier", "%d", &barrier, 1156 NULL); 1157 1158 /* 1159 * If there's no "feature-barrier" defined, then it means 1160 * we're dealing with a very old backend which writes 1161 * synchronously; nothing to do. 1162 * 1163 * If there are barriers, then we use flush. 1164 */ 1165 if (!err && barrier) { 1166 info->feature_flush = REQ_FLUSH | REQ_FUA; 1167 info->flush_op = BLKIF_OP_WRITE_BARRIER; 1168 } 1169 /* 1170 * And if there is "feature-flush-cache" use that above 1171 * barriers. 1172 */ 1173 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1174 "feature-flush-cache", "%d", &flush, 1175 NULL); 1176 1177 if (!err && flush) { 1178 info->feature_flush = REQ_FLUSH; 1179 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE; 1180 } 1181 1182 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size); 1183 if (err) { 1184 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 1185 info->xbdev->otherend); 1186 return; 1187 } 1188 1189 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1190 1191 /* Kick pending requests. */ 1192 spin_lock_irq(&blkif_io_lock); 1193 info->connected = BLKIF_STATE_CONNECTED; 1194 kick_pending_request_queues(info); 1195 spin_unlock_irq(&blkif_io_lock); 1196 1197 add_disk(info->gd); 1198 1199 info->is_ready = 1; 1200 } 1201 1202 /** 1203 * Callback received when the backend's state changes. 1204 */ 1205 static void blkback_changed(struct xenbus_device *dev, 1206 enum xenbus_state backend_state) 1207 { 1208 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1209 1210 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 1211 1212 switch (backend_state) { 1213 case XenbusStateInitialising: 1214 case XenbusStateInitWait: 1215 case XenbusStateInitialised: 1216 case XenbusStateReconfiguring: 1217 case XenbusStateReconfigured: 1218 case XenbusStateUnknown: 1219 case XenbusStateClosed: 1220 break; 1221 1222 case XenbusStateConnected: 1223 blkfront_connect(info); 1224 break; 1225 1226 case XenbusStateClosing: 1227 blkfront_closing(info); 1228 break; 1229 } 1230 } 1231 1232 static int blkfront_remove(struct xenbus_device *xbdev) 1233 { 1234 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 1235 struct block_device *bdev = NULL; 1236 struct gendisk *disk; 1237 1238 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 1239 1240 blkif_free(info, 0); 1241 1242 mutex_lock(&info->mutex); 1243 1244 disk = info->gd; 1245 if (disk) 1246 bdev = bdget_disk(disk, 0); 1247 1248 info->xbdev = NULL; 1249 mutex_unlock(&info->mutex); 1250 1251 if (!bdev) { 1252 kfree(info); 1253 return 0; 1254 } 1255 1256 /* 1257 * The xbdev was removed before we reached the Closed 1258 * state. See if it's safe to remove the disk. If the bdev 1259 * isn't closed yet, we let release take care of it. 1260 */ 1261 1262 mutex_lock(&bdev->bd_mutex); 1263 info = disk->private_data; 1264 1265 dev_warn(disk_to_dev(disk), 1266 "%s was hot-unplugged, %d stale handles\n", 1267 xbdev->nodename, bdev->bd_openers); 1268 1269 if (info && !bdev->bd_openers) { 1270 xlvbd_release_gendisk(info); 1271 disk->private_data = NULL; 1272 kfree(info); 1273 } 1274 1275 mutex_unlock(&bdev->bd_mutex); 1276 bdput(bdev); 1277 1278 return 0; 1279 } 1280 1281 static int blkfront_is_ready(struct xenbus_device *dev) 1282 { 1283 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1284 1285 return info->is_ready && info->xbdev; 1286 } 1287 1288 static int blkif_open(struct block_device *bdev, fmode_t mode) 1289 { 1290 struct gendisk *disk = bdev->bd_disk; 1291 struct blkfront_info *info; 1292 int err = 0; 1293 1294 mutex_lock(&blkfront_mutex); 1295 1296 info = disk->private_data; 1297 if (!info) { 1298 /* xbdev gone */ 1299 err = -ERESTARTSYS; 1300 goto out; 1301 } 1302 1303 mutex_lock(&info->mutex); 1304 1305 if (!info->gd) 1306 /* xbdev is closed */ 1307 err = -ERESTARTSYS; 1308 1309 mutex_unlock(&info->mutex); 1310 1311 out: 1312 mutex_unlock(&blkfront_mutex); 1313 return err; 1314 } 1315 1316 static int blkif_release(struct gendisk *disk, fmode_t mode) 1317 { 1318 struct blkfront_info *info = disk->private_data; 1319 struct block_device *bdev; 1320 struct xenbus_device *xbdev; 1321 1322 mutex_lock(&blkfront_mutex); 1323 1324 bdev = bdget_disk(disk, 0); 1325 bdput(bdev); 1326 1327 if (bdev->bd_openers) 1328 goto out; 1329 1330 /* 1331 * Check if we have been instructed to close. We will have 1332 * deferred this request, because the bdev was still open. 1333 */ 1334 1335 mutex_lock(&info->mutex); 1336 xbdev = info->xbdev; 1337 1338 if (xbdev && xbdev->state == XenbusStateClosing) { 1339 /* pending switch to state closed */ 1340 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 1341 xlvbd_release_gendisk(info); 1342 xenbus_frontend_closed(info->xbdev); 1343 } 1344 1345 mutex_unlock(&info->mutex); 1346 1347 if (!xbdev) { 1348 /* sudden device removal */ 1349 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 1350 xlvbd_release_gendisk(info); 1351 disk->private_data = NULL; 1352 kfree(info); 1353 } 1354 1355 out: 1356 mutex_unlock(&blkfront_mutex); 1357 return 0; 1358 } 1359 1360 static const struct block_device_operations xlvbd_block_fops = 1361 { 1362 .owner = THIS_MODULE, 1363 .open = blkif_open, 1364 .release = blkif_release, 1365 .getgeo = blkif_getgeo, 1366 .ioctl = blkif_ioctl, 1367 }; 1368 1369 1370 static const struct xenbus_device_id blkfront_ids[] = { 1371 { "vbd" }, 1372 { "" } 1373 }; 1374 1375 static struct xenbus_driver blkfront = { 1376 .name = "vbd", 1377 .owner = THIS_MODULE, 1378 .ids = blkfront_ids, 1379 .probe = blkfront_probe, 1380 .remove = blkfront_remove, 1381 .resume = blkfront_resume, 1382 .otherend_changed = blkback_changed, 1383 .is_ready = blkfront_is_ready, 1384 }; 1385 1386 static int __init xlblk_init(void) 1387 { 1388 if (!xen_domain()) 1389 return -ENODEV; 1390 1391 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 1392 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 1393 XENVBD_MAJOR, DEV_NAME); 1394 return -ENODEV; 1395 } 1396 1397 return xenbus_register_frontend(&blkfront); 1398 } 1399 module_init(xlblk_init); 1400 1401 1402 static void __exit xlblk_exit(void) 1403 { 1404 return xenbus_unregister_driver(&blkfront); 1405 } 1406 module_exit(xlblk_exit); 1407 1408 MODULE_DESCRIPTION("Xen virtual block device frontend"); 1409 MODULE_LICENSE("GPL"); 1410 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 1411 MODULE_ALIAS("xen:vbd"); 1412 MODULE_ALIAS("xenblk"); 1413