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