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