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