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#include <linux/bitmap.h> 47#include <linux/list.h> 48 49#include <xen/xen.h> 50#include <xen/xenbus.h> 51#include <xen/grant_table.h> 52#include <xen/events.h> 53#include <xen/page.h> 54#include <xen/platform_pci.h> 55 56#include <xen/interface/grant_table.h> 57#include <xen/interface/io/blkif.h> 58#include <xen/interface/io/protocols.h> 59 60#include <asm/xen/hypervisor.h> 61 62enum blkif_state { 63 BLKIF_STATE_DISCONNECTED, 64 BLKIF_STATE_CONNECTED, 65 BLKIF_STATE_SUSPENDED, 66}; 67 68struct grant { 69 grant_ref_t gref; 70 unsigned long pfn; 71 struct list_head node; 72}; 73 74struct blk_shadow { 75 struct blkif_request req; 76 struct request *request; 77 struct grant **grants_used; 78 struct grant **indirect_grants; 79 struct scatterlist *sg; 80}; 81 82struct split_bio { 83 struct bio *bio; 84 atomic_t pending; 85 int err; 86}; 87 88static DEFINE_MUTEX(blkfront_mutex); 89static const struct block_device_operations xlvbd_block_fops; 90 91/* 92 * Maximum number of segments in indirect requests, the actual value used by 93 * the frontend driver is the minimum of this value and the value provided 94 * by the backend driver. 95 */ 96 97static unsigned int xen_blkif_max_segments = 32; 98module_param_named(max, xen_blkif_max_segments, int, S_IRUGO); 99MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)"); 100 101#define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) 102 103/* 104 * We have one of these per vbd, whether ide, scsi or 'other'. They 105 * hang in private_data off the gendisk structure. We may end up 106 * putting all kinds of interesting stuff here :-) 107 */ 108struct blkfront_info 109{ 110 spinlock_t io_lock; 111 struct mutex mutex; 112 struct xenbus_device *xbdev; 113 struct gendisk *gd; 114 int vdevice; 115 blkif_vdev_t handle; 116 enum blkif_state connected; 117 int ring_ref; 118 struct blkif_front_ring ring; 119 unsigned int evtchn, irq; 120 struct request_queue *rq; 121 struct work_struct work; 122 struct gnttab_free_callback callback; 123 struct blk_shadow shadow[BLK_RING_SIZE]; 124 struct list_head grants; 125 struct list_head indirect_pages; 126 unsigned int persistent_gnts_c; 127 unsigned long shadow_free; 128 unsigned int feature_flush; 129 unsigned int flush_op; 130 unsigned int feature_discard:1; 131 unsigned int feature_secdiscard:1; 132 unsigned int discard_granularity; 133 unsigned int discard_alignment; 134 unsigned int feature_persistent:1; 135 unsigned int max_indirect_segments; 136 int is_ready; 137}; 138 139static unsigned int nr_minors; 140static unsigned long *minors; 141static DEFINE_SPINLOCK(minor_lock); 142 143#define MAXIMUM_OUTSTANDING_BLOCK_REQS \ 144 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE) 145#define GRANT_INVALID_REF 0 146 147#define PARTS_PER_DISK 16 148#define PARTS_PER_EXT_DISK 256 149 150#define BLKIF_MAJOR(dev) ((dev)>>8) 151#define BLKIF_MINOR(dev) ((dev) & 0xff) 152 153#define EXT_SHIFT 28 154#define EXTENDED (1<<EXT_SHIFT) 155#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 156#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 157#define EMULATED_HD_DISK_MINOR_OFFSET (0) 158#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 159#define EMULATED_SD_DISK_MINOR_OFFSET (0) 160#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 161 162#define DEV_NAME "xvd" /* name in /dev */ 163 164#define SEGS_PER_INDIRECT_FRAME \ 165 (PAGE_SIZE/sizeof(struct blkif_request_segment)) 166#define INDIRECT_GREFS(_segs) \ 167 ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME) 168 169static int blkfront_setup_indirect(struct blkfront_info *info); 170 171static int get_id_from_freelist(struct blkfront_info *info) 172{ 173 unsigned long free = info->shadow_free; 174 BUG_ON(free >= BLK_RING_SIZE); 175 info->shadow_free = info->shadow[free].req.u.rw.id; 176 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 177 return free; 178} 179 180static int add_id_to_freelist(struct blkfront_info *info, 181 unsigned long id) 182{ 183 if (info->shadow[id].req.u.rw.id != id) 184 return -EINVAL; 185 if (info->shadow[id].request == NULL) 186 return -EINVAL; 187 info->shadow[id].req.u.rw.id = info->shadow_free; 188 info->shadow[id].request = NULL; 189 info->shadow_free = id; 190 return 0; 191} 192 193static int fill_grant_buffer(struct blkfront_info *info, int num) 194{ 195 struct page *granted_page; 196 struct grant *gnt_list_entry, *n; 197 int i = 0; 198 199 while(i < num) { 200 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 201 if (!gnt_list_entry) 202 goto out_of_memory; 203 204 if (info->feature_persistent) { 205 granted_page = alloc_page(GFP_NOIO); 206 if (!granted_page) { 207 kfree(gnt_list_entry); 208 goto out_of_memory; 209 } 210 gnt_list_entry->pfn = page_to_pfn(granted_page); 211 } 212 213 gnt_list_entry->gref = GRANT_INVALID_REF; 214 list_add(&gnt_list_entry->node, &info->grants); 215 i++; 216 } 217 218 return 0; 219 220out_of_memory: 221 list_for_each_entry_safe(gnt_list_entry, n, 222 &info->grants, node) { 223 list_del(&gnt_list_entry->node); 224 if (info->feature_persistent) 225 __free_page(pfn_to_page(gnt_list_entry->pfn)); 226 kfree(gnt_list_entry); 227 i--; 228 } 229 BUG_ON(i != 0); 230 return -ENOMEM; 231} 232 233static struct grant *get_grant(grant_ref_t *gref_head, 234 unsigned long pfn, 235 struct blkfront_info *info) 236{ 237 struct grant *gnt_list_entry; 238 unsigned long buffer_mfn; 239 240 BUG_ON(list_empty(&info->grants)); 241 gnt_list_entry = list_first_entry(&info->grants, struct grant, 242 node); 243 list_del(&gnt_list_entry->node); 244 245 if (gnt_list_entry->gref != GRANT_INVALID_REF) { 246 info->persistent_gnts_c--; 247 return gnt_list_entry; 248 } 249 250 /* Assign a gref to this page */ 251 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 252 BUG_ON(gnt_list_entry->gref == -ENOSPC); 253 if (!info->feature_persistent) { 254 BUG_ON(!pfn); 255 gnt_list_entry->pfn = pfn; 256 } 257 buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); 258 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 259 info->xbdev->otherend_id, 260 buffer_mfn, 0); 261 return gnt_list_entry; 262} 263 264static const char *op_name(int op) 265{ 266 static const char *const names[] = { 267 [BLKIF_OP_READ] = "read", 268 [BLKIF_OP_WRITE] = "write", 269 [BLKIF_OP_WRITE_BARRIER] = "barrier", 270 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 271 [BLKIF_OP_DISCARD] = "discard" }; 272 273 if (op < 0 || op >= ARRAY_SIZE(names)) 274 return "unknown"; 275 276 if (!names[op]) 277 return "reserved"; 278 279 return names[op]; 280} 281static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 282{ 283 unsigned int end = minor + nr; 284 int rc; 285 286 if (end > nr_minors) { 287 unsigned long *bitmap, *old; 288 289 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 290 GFP_KERNEL); 291 if (bitmap == NULL) 292 return -ENOMEM; 293 294 spin_lock(&minor_lock); 295 if (end > nr_minors) { 296 old = minors; 297 memcpy(bitmap, minors, 298 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 299 minors = bitmap; 300 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 301 } else 302 old = bitmap; 303 spin_unlock(&minor_lock); 304 kfree(old); 305 } 306 307 spin_lock(&minor_lock); 308 if (find_next_bit(minors, end, minor) >= end) { 309 bitmap_set(minors, minor, nr); 310 rc = 0; 311 } else 312 rc = -EBUSY; 313 spin_unlock(&minor_lock); 314 315 return rc; 316} 317 318static void xlbd_release_minors(unsigned int minor, unsigned int nr) 319{ 320 unsigned int end = minor + nr; 321 322 BUG_ON(end > nr_minors); 323 spin_lock(&minor_lock); 324 bitmap_clear(minors, minor, nr); 325 spin_unlock(&minor_lock); 326} 327 328static void blkif_restart_queue_callback(void *arg) 329{ 330 struct blkfront_info *info = (struct blkfront_info *)arg; 331 schedule_work(&info->work); 332} 333 334static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 335{ 336 /* We don't have real geometry info, but let's at least return 337 values consistent with the size of the device */ 338 sector_t nsect = get_capacity(bd->bd_disk); 339 sector_t cylinders = nsect; 340 341 hg->heads = 0xff; 342 hg->sectors = 0x3f; 343 sector_div(cylinders, hg->heads * hg->sectors); 344 hg->cylinders = cylinders; 345 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 346 hg->cylinders = 0xffff; 347 return 0; 348} 349 350static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 351 unsigned command, unsigned long argument) 352{ 353 struct blkfront_info *info = bdev->bd_disk->private_data; 354 int i; 355 356 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 357 command, (long)argument); 358 359 switch (command) { 360 case CDROMMULTISESSION: 361 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 362 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 363 if (put_user(0, (char __user *)(argument + i))) 364 return -EFAULT; 365 return 0; 366 367 case CDROM_GET_CAPABILITY: { 368 struct gendisk *gd = info->gd; 369 if (gd->flags & GENHD_FL_CD) 370 return 0; 371 return -EINVAL; 372 } 373 374 default: 375 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 376 command);*/ 377 return -EINVAL; /* same return as native Linux */ 378 } 379 380 return 0; 381} 382 383/* 384 * Generate a Xen blkfront IO request from a blk layer request. Reads 385 * and writes are handled as expected. 386 * 387 * @req: a request struct 388 */ 389static int blkif_queue_request(struct request *req) 390{ 391 struct blkfront_info *info = req->rq_disk->private_data; 392 struct blkif_request *ring_req; 393 unsigned long id; 394 unsigned int fsect, lsect; 395 int i, ref, n; 396 struct blkif_request_segment *segments = NULL; 397 398 /* 399 * Used to store if we are able to queue the request by just using 400 * existing persistent grants, or if we have to get new grants, 401 * as there are not sufficiently many free. 402 */ 403 bool new_persistent_gnts; 404 grant_ref_t gref_head; 405 struct grant *gnt_list_entry = NULL; 406 struct scatterlist *sg; 407 int nseg, max_grefs; 408 409 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 410 return 1; 411 412 max_grefs = req->nr_phys_segments; 413 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 414 /* 415 * If we are using indirect segments we need to account 416 * for the indirect grefs used in the request. 417 */ 418 max_grefs += INDIRECT_GREFS(req->nr_phys_segments); 419 420 /* Check if we have enough grants to allocate a requests */ 421 if (info->persistent_gnts_c < max_grefs) { 422 new_persistent_gnts = 1; 423 if (gnttab_alloc_grant_references( 424 max_grefs - info->persistent_gnts_c, 425 &gref_head) < 0) { 426 gnttab_request_free_callback( 427 &info->callback, 428 blkif_restart_queue_callback, 429 info, 430 max_grefs); 431 return 1; 432 } 433 } else 434 new_persistent_gnts = 0; 435 436 /* Fill out a communications ring structure. */ 437 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); 438 id = get_id_from_freelist(info); 439 info->shadow[id].request = req; 440 441 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) { 442 ring_req->operation = BLKIF_OP_DISCARD; 443 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 444 ring_req->u.discard.id = id; 445 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 446 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) 447 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 448 else 449 ring_req->u.discard.flag = 0; 450 } else { 451 BUG_ON(info->max_indirect_segments == 0 && 452 req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST); 453 BUG_ON(info->max_indirect_segments && 454 req->nr_phys_segments > info->max_indirect_segments); 455 nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg); 456 ring_req->u.rw.id = id; 457 if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) { 458 /* 459 * The indirect operation can only be a BLKIF_OP_READ or 460 * BLKIF_OP_WRITE 461 */ 462 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA)); 463 ring_req->operation = BLKIF_OP_INDIRECT; 464 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 465 BLKIF_OP_WRITE : BLKIF_OP_READ; 466 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 467 ring_req->u.indirect.handle = info->handle; 468 ring_req->u.indirect.nr_segments = nseg; 469 } else { 470 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 471 ring_req->u.rw.handle = info->handle; 472 ring_req->operation = rq_data_dir(req) ? 473 BLKIF_OP_WRITE : BLKIF_OP_READ; 474 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { 475 /* 476 * Ideally we can do an unordered flush-to-disk. In case the 477 * backend onlysupports barriers, use that. A barrier request 478 * a superset of FUA, so we can implement it the same 479 * way. (It's also a FLUSH+FUA, since it is 480 * guaranteed ordered WRT previous writes.) 481 */ 482 ring_req->operation = info->flush_op; 483 } 484 ring_req->u.rw.nr_segments = nseg; 485 } 486 for_each_sg(info->shadow[id].sg, sg, nseg, i) { 487 fsect = sg->offset >> 9; 488 lsect = fsect + (sg->length >> 9) - 1; 489 490 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 491 (i % SEGS_PER_INDIRECT_FRAME == 0)) { 492 unsigned long uninitialized_var(pfn); 493 494 if (segments) 495 kunmap_atomic(segments); 496 497 n = i / SEGS_PER_INDIRECT_FRAME; 498 if (!info->feature_persistent) { 499 struct page *indirect_page; 500 501 /* Fetch a pre-allocated page to use for indirect grefs */ 502 BUG_ON(list_empty(&info->indirect_pages)); 503 indirect_page = list_first_entry(&info->indirect_pages, 504 struct page, lru); 505 list_del(&indirect_page->lru); 506 pfn = page_to_pfn(indirect_page); 507 } 508 gnt_list_entry = get_grant(&gref_head, pfn, info); 509 info->shadow[id].indirect_grants[n] = gnt_list_entry; 510 segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); 511 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 512 } 513 514 gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info); 515 ref = gnt_list_entry->gref; 516 517 info->shadow[id].grants_used[i] = gnt_list_entry; 518 519 if (rq_data_dir(req) && info->feature_persistent) { 520 char *bvec_data; 521 void *shared_data; 522 523 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 524 525 shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); 526 bvec_data = kmap_atomic(sg_page(sg)); 527 528 /* 529 * this does not wipe data stored outside the 530 * range sg->offset..sg->offset+sg->length. 531 * Therefore, blkback *could* see data from 532 * previous requests. This is OK as long as 533 * persistent grants are shared with just one 534 * domain. It may need refactoring if this 535 * changes 536 */ 537 memcpy(shared_data + sg->offset, 538 bvec_data + sg->offset, 539 sg->length); 540 541 kunmap_atomic(bvec_data); 542 kunmap_atomic(shared_data); 543 } 544 if (ring_req->operation != BLKIF_OP_INDIRECT) { 545 ring_req->u.rw.seg[i] = 546 (struct blkif_request_segment) { 547 .gref = ref, 548 .first_sect = fsect, 549 .last_sect = lsect }; 550 } else { 551 n = i % SEGS_PER_INDIRECT_FRAME; 552 segments[n] = 553 (struct blkif_request_segment) { 554 .gref = ref, 555 .first_sect = fsect, 556 .last_sect = lsect }; 557 } 558 } 559 if (segments) 560 kunmap_atomic(segments); 561 } 562 563 info->ring.req_prod_pvt++; 564 565 /* Keep a private copy so we can reissue requests when recovering. */ 566 info->shadow[id].req = *ring_req; 567 568 if (new_persistent_gnts) 569 gnttab_free_grant_references(gref_head); 570 571 return 0; 572} 573 574 575static inline void flush_requests(struct blkfront_info *info) 576{ 577 int notify; 578 579 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); 580 581 if (notify) 582 notify_remote_via_irq(info->irq); 583} 584 585static inline bool blkif_request_flush_valid(struct request *req, 586 struct blkfront_info *info) 587{ 588 return ((req->cmd_type != REQ_TYPE_FS) || 589 ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) && 590 !info->flush_op)); 591} 592 593/* 594 * do_blkif_request 595 * read a block; request is in a request queue 596 */ 597static void do_blkif_request(struct request_queue *rq) 598{ 599 struct blkfront_info *info = NULL; 600 struct request *req; 601 int queued; 602 603 pr_debug("Entered do_blkif_request\n"); 604 605 queued = 0; 606 607 while ((req = blk_peek_request(rq)) != NULL) { 608 info = req->rq_disk->private_data; 609 610 if (RING_FULL(&info->ring)) 611 goto wait; 612 613 blk_start_request(req); 614 615 if (blkif_request_flush_valid(req, info)) { 616 __blk_end_request_all(req, -EIO); 617 continue; 618 } 619 620 pr_debug("do_blk_req %p: cmd %p, sec %lx, " 621 "(%u/%u) [%s]\n", 622 req, req->cmd, (unsigned long)blk_rq_pos(req), 623 blk_rq_cur_sectors(req), blk_rq_sectors(req), 624 rq_data_dir(req) ? "write" : "read"); 625 626 if (blkif_queue_request(req)) { 627 blk_requeue_request(rq, req); 628wait: 629 /* Avoid pointless unplugs. */ 630 blk_stop_queue(rq); 631 break; 632 } 633 634 queued++; 635 } 636 637 if (queued != 0) 638 flush_requests(info); 639} 640 641static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, 642 unsigned int physical_sector_size, 643 unsigned int segments) 644{ 645 struct request_queue *rq; 646 struct blkfront_info *info = gd->private_data; 647 648 rq = blk_init_queue(do_blkif_request, &info->io_lock); 649 if (rq == NULL) 650 return -1; 651 652 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 653 654 if (info->feature_discard) { 655 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); 656 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 657 rq->limits.discard_granularity = info->discard_granularity; 658 rq->limits.discard_alignment = info->discard_alignment; 659 if (info->feature_secdiscard) 660 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq); 661 } 662 663 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 664 blk_queue_logical_block_size(rq, sector_size); 665 blk_queue_physical_block_size(rq, physical_sector_size); 666 blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512); 667 668 /* Each segment in a request is up to an aligned page in size. */ 669 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 670 blk_queue_max_segment_size(rq, PAGE_SIZE); 671 672 /* Ensure a merged request will fit in a single I/O ring slot. */ 673 blk_queue_max_segments(rq, segments); 674 675 /* Make sure buffer addresses are sector-aligned. */ 676 blk_queue_dma_alignment(rq, 511); 677 678 /* Make sure we don't use bounce buffers. */ 679 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); 680 681 gd->queue = rq; 682 683 return 0; 684} 685 686 687static void xlvbd_flush(struct blkfront_info *info) 688{ 689 blk_queue_flush(info->rq, info->feature_flush); 690 printk(KERN_INFO "blkfront: %s: %s: %s %s %s %s %s\n", 691 info->gd->disk_name, 692 info->flush_op == BLKIF_OP_WRITE_BARRIER ? 693 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ? 694 "flush diskcache" : "barrier or flush"), 695 info->feature_flush ? "enabled;" : "disabled;", 696 "persistent grants:", 697 info->feature_persistent ? "enabled;" : "disabled;", 698 "indirect descriptors:", 699 info->max_indirect_segments ? "enabled;" : "disabled;"); 700} 701 702static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 703{ 704 int major; 705 major = BLKIF_MAJOR(vdevice); 706 *minor = BLKIF_MINOR(vdevice); 707 switch (major) { 708 case XEN_IDE0_MAJOR: 709 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 710 *minor = ((*minor / 64) * PARTS_PER_DISK) + 711 EMULATED_HD_DISK_MINOR_OFFSET; 712 break; 713 case XEN_IDE1_MAJOR: 714 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 715 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 716 EMULATED_HD_DISK_MINOR_OFFSET; 717 break; 718 case XEN_SCSI_DISK0_MAJOR: 719 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 720 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 721 break; 722 case XEN_SCSI_DISK1_MAJOR: 723 case XEN_SCSI_DISK2_MAJOR: 724 case XEN_SCSI_DISK3_MAJOR: 725 case XEN_SCSI_DISK4_MAJOR: 726 case XEN_SCSI_DISK5_MAJOR: 727 case XEN_SCSI_DISK6_MAJOR: 728 case XEN_SCSI_DISK7_MAJOR: 729 *offset = (*minor / PARTS_PER_DISK) + 730 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 731 EMULATED_SD_DISK_NAME_OFFSET; 732 *minor = *minor + 733 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 734 EMULATED_SD_DISK_MINOR_OFFSET; 735 break; 736 case XEN_SCSI_DISK8_MAJOR: 737 case XEN_SCSI_DISK9_MAJOR: 738 case XEN_SCSI_DISK10_MAJOR: 739 case XEN_SCSI_DISK11_MAJOR: 740 case XEN_SCSI_DISK12_MAJOR: 741 case XEN_SCSI_DISK13_MAJOR: 742 case XEN_SCSI_DISK14_MAJOR: 743 case XEN_SCSI_DISK15_MAJOR: 744 *offset = (*minor / PARTS_PER_DISK) + 745 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 746 EMULATED_SD_DISK_NAME_OFFSET; 747 *minor = *minor + 748 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 749 EMULATED_SD_DISK_MINOR_OFFSET; 750 break; 751 case XENVBD_MAJOR: 752 *offset = *minor / PARTS_PER_DISK; 753 break; 754 default: 755 printk(KERN_WARNING "blkfront: your disk configuration is " 756 "incorrect, please use an xvd device instead\n"); 757 return -ENODEV; 758 } 759 return 0; 760} 761 762static char *encode_disk_name(char *ptr, unsigned int n) 763{ 764 if (n >= 26) 765 ptr = encode_disk_name(ptr, n / 26 - 1); 766 *ptr = 'a' + n % 26; 767 return ptr + 1; 768} 769 770static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 771 struct blkfront_info *info, 772 u16 vdisk_info, u16 sector_size, 773 unsigned int physical_sector_size) 774{ 775 struct gendisk *gd; 776 int nr_minors = 1; 777 int err; 778 unsigned int offset; 779 int minor; 780 int nr_parts; 781 char *ptr; 782 783 BUG_ON(info->gd != NULL); 784 BUG_ON(info->rq != NULL); 785 786 if ((info->vdevice>>EXT_SHIFT) > 1) { 787 /* this is above the extended range; something is wrong */ 788 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 789 return -ENODEV; 790 } 791 792 if (!VDEV_IS_EXTENDED(info->vdevice)) { 793 err = xen_translate_vdev(info->vdevice, &minor, &offset); 794 if (err) 795 return err; 796 nr_parts = PARTS_PER_DISK; 797 } else { 798 minor = BLKIF_MINOR_EXT(info->vdevice); 799 nr_parts = PARTS_PER_EXT_DISK; 800 offset = minor / nr_parts; 801 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 802 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 803 "emulated IDE disks,\n\t choose an xvd device name" 804 "from xvde on\n", info->vdevice); 805 } 806 if (minor >> MINORBITS) { 807 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 808 info->vdevice, minor); 809 return -ENODEV; 810 } 811 812 if ((minor % nr_parts) == 0) 813 nr_minors = nr_parts; 814 815 err = xlbd_reserve_minors(minor, nr_minors); 816 if (err) 817 goto out; 818 err = -ENODEV; 819 820 gd = alloc_disk(nr_minors); 821 if (gd == NULL) 822 goto release; 823 824 strcpy(gd->disk_name, DEV_NAME); 825 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 826 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 827 if (nr_minors > 1) 828 *ptr = 0; 829 else 830 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 831 "%d", minor & (nr_parts - 1)); 832 833 gd->major = XENVBD_MAJOR; 834 gd->first_minor = minor; 835 gd->fops = &xlvbd_block_fops; 836 gd->private_data = info; 837 gd->driverfs_dev = &(info->xbdev->dev); 838 set_capacity(gd, capacity); 839 840 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size, 841 info->max_indirect_segments ? : 842 BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 843 del_gendisk(gd); 844 goto release; 845 } 846 847 info->rq = gd->queue; 848 info->gd = gd; 849 850 xlvbd_flush(info); 851 852 if (vdisk_info & VDISK_READONLY) 853 set_disk_ro(gd, 1); 854 855 if (vdisk_info & VDISK_REMOVABLE) 856 gd->flags |= GENHD_FL_REMOVABLE; 857 858 if (vdisk_info & VDISK_CDROM) 859 gd->flags |= GENHD_FL_CD; 860 861 return 0; 862 863 release: 864 xlbd_release_minors(minor, nr_minors); 865 out: 866 return err; 867} 868 869static void xlvbd_release_gendisk(struct blkfront_info *info) 870{ 871 unsigned int minor, nr_minors; 872 unsigned long flags; 873 874 if (info->rq == NULL) 875 return; 876 877 spin_lock_irqsave(&info->io_lock, flags); 878 879 /* No more blkif_request(). */ 880 blk_stop_queue(info->rq); 881 882 /* No more gnttab callback work. */ 883 gnttab_cancel_free_callback(&info->callback); 884 spin_unlock_irqrestore(&info->io_lock, flags); 885 886 /* Flush gnttab callback work. Must be done with no locks held. */ 887 flush_work(&info->work); 888 889 del_gendisk(info->gd); 890 891 minor = info->gd->first_minor; 892 nr_minors = info->gd->minors; 893 xlbd_release_minors(minor, nr_minors); 894 895 blk_cleanup_queue(info->rq); 896 info->rq = NULL; 897 898 put_disk(info->gd); 899 info->gd = NULL; 900} 901 902static void kick_pending_request_queues(struct blkfront_info *info) 903{ 904 if (!RING_FULL(&info->ring)) { 905 /* Re-enable calldowns. */ 906 blk_start_queue(info->rq); 907 /* Kick things off immediately. */ 908 do_blkif_request(info->rq); 909 } 910} 911 912static void blkif_restart_queue(struct work_struct *work) 913{ 914 struct blkfront_info *info = container_of(work, struct blkfront_info, work); 915 916 spin_lock_irq(&info->io_lock); 917 if (info->connected == BLKIF_STATE_CONNECTED) 918 kick_pending_request_queues(info); 919 spin_unlock_irq(&info->io_lock); 920} 921 922static void blkif_free(struct blkfront_info *info, int suspend) 923{ 924 struct grant *persistent_gnt; 925 struct grant *n; 926 int i, j, segs; 927 928 /* Prevent new requests being issued until we fix things up. */ 929 spin_lock_irq(&info->io_lock); 930 info->connected = suspend ? 931 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 932 /* No more blkif_request(). */ 933 if (info->rq) 934 blk_stop_queue(info->rq); 935 936 /* Remove all persistent grants */ 937 if (!list_empty(&info->grants)) { 938 list_for_each_entry_safe(persistent_gnt, n, 939 &info->grants, node) { 940 list_del(&persistent_gnt->node); 941 if (persistent_gnt->gref != GRANT_INVALID_REF) { 942 gnttab_end_foreign_access(persistent_gnt->gref, 943 0, 0UL); 944 info->persistent_gnts_c--; 945 } 946 if (info->feature_persistent) 947 __free_page(pfn_to_page(persistent_gnt->pfn)); 948 kfree(persistent_gnt); 949 } 950 } 951 BUG_ON(info->persistent_gnts_c != 0); 952 953 /* 954 * Remove indirect pages, this only happens when using indirect 955 * descriptors but not persistent grants 956 */ 957 if (!list_empty(&info->indirect_pages)) { 958 struct page *indirect_page, *n; 959 960 BUG_ON(info->feature_persistent); 961 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 962 list_del(&indirect_page->lru); 963 __free_page(indirect_page); 964 } 965 } 966 967 for (i = 0; i < BLK_RING_SIZE; i++) { 968 /* 969 * Clear persistent grants present in requests already 970 * on the shared ring 971 */ 972 if (!info->shadow[i].request) 973 goto free_shadow; 974 975 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 976 info->shadow[i].req.u.indirect.nr_segments : 977 info->shadow[i].req.u.rw.nr_segments; 978 for (j = 0; j < segs; j++) { 979 persistent_gnt = info->shadow[i].grants_used[j]; 980 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 981 if (info->feature_persistent) 982 __free_page(pfn_to_page(persistent_gnt->pfn)); 983 kfree(persistent_gnt); 984 } 985 986 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT) 987 /* 988 * If this is not an indirect operation don't try to 989 * free indirect segments 990 */ 991 goto free_shadow; 992 993 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 994 persistent_gnt = info->shadow[i].indirect_grants[j]; 995 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 996 __free_page(pfn_to_page(persistent_gnt->pfn)); 997 kfree(persistent_gnt); 998 } 999 1000free_shadow: 1001 kfree(info->shadow[i].grants_used); 1002 info->shadow[i].grants_used = NULL; 1003 kfree(info->shadow[i].indirect_grants); 1004 info->shadow[i].indirect_grants = NULL; 1005 kfree(info->shadow[i].sg); 1006 info->shadow[i].sg = NULL; 1007 } 1008 1009 /* No more gnttab callback work. */ 1010 gnttab_cancel_free_callback(&info->callback); 1011 spin_unlock_irq(&info->io_lock); 1012 1013 /* Flush gnttab callback work. Must be done with no locks held. */ 1014 flush_work(&info->work); 1015 1016 /* Free resources associated with old device channel. */ 1017 if (info->ring_ref != GRANT_INVALID_REF) { 1018 gnttab_end_foreign_access(info->ring_ref, 0, 1019 (unsigned long)info->ring.sring); 1020 info->ring_ref = GRANT_INVALID_REF; 1021 info->ring.sring = NULL; 1022 } 1023 if (info->irq) 1024 unbind_from_irqhandler(info->irq, info); 1025 info->evtchn = info->irq = 0; 1026 1027} 1028 1029static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, 1030 struct blkif_response *bret) 1031{ 1032 int i = 0; 1033 struct scatterlist *sg; 1034 char *bvec_data; 1035 void *shared_data; 1036 int nseg; 1037 1038 nseg = s->req.operation == BLKIF_OP_INDIRECT ? 1039 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1040 1041 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { 1042 /* 1043 * Copy the data received from the backend into the bvec. 1044 * Since bv_offset can be different than 0, and bv_len different 1045 * than PAGE_SIZE, we have to keep track of the current offset, 1046 * to be sure we are copying the data from the right shared page. 1047 */ 1048 for_each_sg(s->sg, sg, nseg, i) { 1049 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1050 shared_data = kmap_atomic( 1051 pfn_to_page(s->grants_used[i]->pfn)); 1052 bvec_data = kmap_atomic(sg_page(sg)); 1053 memcpy(bvec_data + sg->offset, 1054 shared_data + sg->offset, 1055 sg->length); 1056 kunmap_atomic(bvec_data); 1057 kunmap_atomic(shared_data); 1058 } 1059 } 1060 /* Add the persistent grant into the list of free grants */ 1061 for (i = 0; i < nseg; i++) { 1062 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) { 1063 /* 1064 * If the grant is still mapped by the backend (the 1065 * backend has chosen to make this grant persistent) 1066 * we add it at the head of the list, so it will be 1067 * reused first. 1068 */ 1069 if (!info->feature_persistent) 1070 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1071 s->grants_used[i]->gref); 1072 list_add(&s->grants_used[i]->node, &info->grants); 1073 info->persistent_gnts_c++; 1074 } else { 1075 /* 1076 * If the grant is not mapped by the backend we end the 1077 * foreign access and add it to the tail of the list, 1078 * so it will not be picked again unless we run out of 1079 * persistent grants. 1080 */ 1081 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); 1082 s->grants_used[i]->gref = GRANT_INVALID_REF; 1083 list_add_tail(&s->grants_used[i]->node, &info->grants); 1084 } 1085 } 1086 if (s->req.operation == BLKIF_OP_INDIRECT) { 1087 for (i = 0; i < INDIRECT_GREFS(nseg); i++) { 1088 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { 1089 if (!info->feature_persistent) 1090 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1091 s->indirect_grants[i]->gref); 1092 list_add(&s->indirect_grants[i]->node, &info->grants); 1093 info->persistent_gnts_c++; 1094 } else { 1095 struct page *indirect_page; 1096 1097 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); 1098 /* 1099 * Add the used indirect page back to the list of 1100 * available pages for indirect grefs. 1101 */ 1102 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn); 1103 list_add(&indirect_page->lru, &info->indirect_pages); 1104 s->indirect_grants[i]->gref = GRANT_INVALID_REF; 1105 list_add_tail(&s->indirect_grants[i]->node, &info->grants); 1106 } 1107 } 1108 } 1109} 1110 1111static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1112{ 1113 struct request *req; 1114 struct blkif_response *bret; 1115 RING_IDX i, rp; 1116 unsigned long flags; 1117 struct blkfront_info *info = (struct blkfront_info *)dev_id; 1118 int error; 1119 1120 spin_lock_irqsave(&info->io_lock, flags); 1121 1122 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { 1123 spin_unlock_irqrestore(&info->io_lock, flags); 1124 return IRQ_HANDLED; 1125 } 1126 1127 again: 1128 rp = info->ring.sring->rsp_prod; 1129 rmb(); /* Ensure we see queued responses up to 'rp'. */ 1130 1131 for (i = info->ring.rsp_cons; i != rp; i++) { 1132 unsigned long id; 1133 1134 bret = RING_GET_RESPONSE(&info->ring, i); 1135 id = bret->id; 1136 /* 1137 * The backend has messed up and given us an id that we would 1138 * never have given to it (we stamp it up to BLK_RING_SIZE - 1139 * look in get_id_from_freelist. 1140 */ 1141 if (id >= BLK_RING_SIZE) { 1142 WARN(1, "%s: response to %s has incorrect id (%ld)\n", 1143 info->gd->disk_name, op_name(bret->operation), id); 1144 /* We can't safely get the 'struct request' as 1145 * the id is busted. */ 1146 continue; 1147 } 1148 req = info->shadow[id].request; 1149 1150 if (bret->operation != BLKIF_OP_DISCARD) 1151 blkif_completion(&info->shadow[id], info, bret); 1152 1153 if (add_id_to_freelist(info, id)) { 1154 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1155 info->gd->disk_name, op_name(bret->operation), id); 1156 continue; 1157 } 1158 1159 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; 1160 switch (bret->operation) { 1161 case BLKIF_OP_DISCARD: 1162 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1163 struct request_queue *rq = info->rq; 1164 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1165 info->gd->disk_name, op_name(bret->operation)); 1166 error = -EOPNOTSUPP; 1167 info->feature_discard = 0; 1168 info->feature_secdiscard = 0; 1169 queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 1170 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq); 1171 } 1172 __blk_end_request_all(req, error); 1173 break; 1174 case BLKIF_OP_FLUSH_DISKCACHE: 1175 case BLKIF_OP_WRITE_BARRIER: 1176 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1177 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1178 info->gd->disk_name, op_name(bret->operation)); 1179 error = -EOPNOTSUPP; 1180 } 1181 if (unlikely(bret->status == BLKIF_RSP_ERROR && 1182 info->shadow[id].req.u.rw.nr_segments == 0)) { 1183 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", 1184 info->gd->disk_name, op_name(bret->operation)); 1185 error = -EOPNOTSUPP; 1186 } 1187 if (unlikely(error)) { 1188 if (error == -EOPNOTSUPP) 1189 error = 0; 1190 info->feature_flush = 0; 1191 info->flush_op = 0; 1192 xlvbd_flush(info); 1193 } 1194 /* fall through */ 1195 case BLKIF_OP_READ: 1196 case BLKIF_OP_WRITE: 1197 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 1198 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 1199 "request: %x\n", bret->status); 1200 1201 __blk_end_request_all(req, error); 1202 break; 1203 default: 1204 BUG(); 1205 } 1206 } 1207 1208 info->ring.rsp_cons = i; 1209 1210 if (i != info->ring.req_prod_pvt) { 1211 int more_to_do; 1212 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 1213 if (more_to_do) 1214 goto again; 1215 } else 1216 info->ring.sring->rsp_event = i + 1; 1217 1218 kick_pending_request_queues(info); 1219 1220 spin_unlock_irqrestore(&info->io_lock, flags); 1221 1222 return IRQ_HANDLED; 1223} 1224 1225 1226static int setup_blkring(struct xenbus_device *dev, 1227 struct blkfront_info *info) 1228{ 1229 struct blkif_sring *sring; 1230 int err; 1231 1232 info->ring_ref = GRANT_INVALID_REF; 1233 1234 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH); 1235 if (!sring) { 1236 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1237 return -ENOMEM; 1238 } 1239 SHARED_RING_INIT(sring); 1240 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 1241 1242 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); 1243 if (err < 0) { 1244 free_page((unsigned long)sring); 1245 info->ring.sring = NULL; 1246 goto fail; 1247 } 1248 info->ring_ref = err; 1249 1250 err = xenbus_alloc_evtchn(dev, &info->evtchn); 1251 if (err) 1252 goto fail; 1253 1254 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0, 1255 "blkif", info); 1256 if (err <= 0) { 1257 xenbus_dev_fatal(dev, err, 1258 "bind_evtchn_to_irqhandler failed"); 1259 goto fail; 1260 } 1261 info->irq = err; 1262 1263 return 0; 1264fail: 1265 blkif_free(info, 0); 1266 return err; 1267} 1268 1269 1270/* Common code used when first setting up, and when resuming. */ 1271static int talk_to_blkback(struct xenbus_device *dev, 1272 struct blkfront_info *info) 1273{ 1274 const char *message = NULL; 1275 struct xenbus_transaction xbt; 1276 int err; 1277 1278 /* Create shared ring, alloc event channel. */ 1279 err = setup_blkring(dev, info); 1280 if (err) 1281 goto out; 1282 1283again: 1284 err = xenbus_transaction_start(&xbt); 1285 if (err) { 1286 xenbus_dev_fatal(dev, err, "starting transaction"); 1287 goto destroy_blkring; 1288 } 1289 1290 err = xenbus_printf(xbt, dev->nodename, 1291 "ring-ref", "%u", info->ring_ref); 1292 if (err) { 1293 message = "writing ring-ref"; 1294 goto abort_transaction; 1295 } 1296 err = xenbus_printf(xbt, dev->nodename, 1297 "event-channel", "%u", info->evtchn); 1298 if (err) { 1299 message = "writing event-channel"; 1300 goto abort_transaction; 1301 } 1302 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1303 XEN_IO_PROTO_ABI_NATIVE); 1304 if (err) { 1305 message = "writing protocol"; 1306 goto abort_transaction; 1307 } 1308 err = xenbus_printf(xbt, dev->nodename, 1309 "feature-persistent", "%u", 1); 1310 if (err) 1311 dev_warn(&dev->dev, 1312 "writing persistent grants feature to xenbus"); 1313 1314 err = xenbus_transaction_end(xbt, 0); 1315 if (err) { 1316 if (err == -EAGAIN) 1317 goto again; 1318 xenbus_dev_fatal(dev, err, "completing transaction"); 1319 goto destroy_blkring; 1320 } 1321 1322 xenbus_switch_state(dev, XenbusStateInitialised); 1323 1324 return 0; 1325 1326 abort_transaction: 1327 xenbus_transaction_end(xbt, 1); 1328 if (message) 1329 xenbus_dev_fatal(dev, err, "%s", message); 1330 destroy_blkring: 1331 blkif_free(info, 0); 1332 out: 1333 return err; 1334} 1335 1336/** 1337 * Entry point to this code when a new device is created. Allocate the basic 1338 * structures and the ring buffer for communication with the backend, and 1339 * inform the backend of the appropriate details for those. Switch to 1340 * Initialised state. 1341 */ 1342static int blkfront_probe(struct xenbus_device *dev, 1343 const struct xenbus_device_id *id) 1344{ 1345 int err, vdevice, i; 1346 struct blkfront_info *info; 1347 1348 /* FIXME: Use dynamic device id if this is not set. */ 1349 err = xenbus_scanf(XBT_NIL, dev->nodename, 1350 "virtual-device", "%i", &vdevice); 1351 if (err != 1) { 1352 /* go looking in the extended area instead */ 1353 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1354 "%i", &vdevice); 1355 if (err != 1) { 1356 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1357 return err; 1358 } 1359 } 1360 1361 if (xen_hvm_domain()) { 1362 char *type; 1363 int len; 1364 /* no unplug has been done: do not hook devices != xen vbds */ 1365 if (xen_has_pv_and_legacy_disk_devices()) { 1366 int major; 1367 1368 if (!VDEV_IS_EXTENDED(vdevice)) 1369 major = BLKIF_MAJOR(vdevice); 1370 else 1371 major = XENVBD_MAJOR; 1372 1373 if (major != XENVBD_MAJOR) { 1374 printk(KERN_INFO 1375 "%s: HVM does not support vbd %d as xen block device\n", 1376 __FUNCTION__, vdevice); 1377 return -ENODEV; 1378 } 1379 } 1380 /* do not create a PV cdrom device if we are an HVM guest */ 1381 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1382 if (IS_ERR(type)) 1383 return -ENODEV; 1384 if (strncmp(type, "cdrom", 5) == 0) { 1385 kfree(type); 1386 return -ENODEV; 1387 } 1388 kfree(type); 1389 } 1390 info = kzalloc(sizeof(*info), GFP_KERNEL); 1391 if (!info) { 1392 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1393 return -ENOMEM; 1394 } 1395 1396 mutex_init(&info->mutex); 1397 spin_lock_init(&info->io_lock); 1398 info->xbdev = dev; 1399 info->vdevice = vdevice; 1400 INIT_LIST_HEAD(&info->grants); 1401 INIT_LIST_HEAD(&info->indirect_pages); 1402 info->persistent_gnts_c = 0; 1403 info->connected = BLKIF_STATE_DISCONNECTED; 1404 INIT_WORK(&info->work, blkif_restart_queue); 1405 1406 for (i = 0; i < BLK_RING_SIZE; i++) 1407 info->shadow[i].req.u.rw.id = i+1; 1408 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1409 1410 /* Front end dir is a number, which is used as the id. */ 1411 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1412 dev_set_drvdata(&dev->dev, info); 1413 1414 err = talk_to_blkback(dev, info); 1415 if (err) { 1416 kfree(info); 1417 dev_set_drvdata(&dev->dev, NULL); 1418 return err; 1419 } 1420 1421 return 0; 1422} 1423 1424static void split_bio_end(struct bio *bio, int error) 1425{ 1426 struct split_bio *split_bio = bio->bi_private; 1427 1428 if (error) 1429 split_bio->err = error; 1430 1431 if (atomic_dec_and_test(&split_bio->pending)) { 1432 split_bio->bio->bi_phys_segments = 0; 1433 bio_endio(split_bio->bio, split_bio->err); 1434 kfree(split_bio); 1435 } 1436 bio_put(bio); 1437} 1438 1439static int blkif_recover(struct blkfront_info *info) 1440{ 1441 int i; 1442 struct request *req, *n; 1443 struct blk_shadow *copy; 1444 int rc; 1445 struct bio *bio, *cloned_bio; 1446 struct bio_list bio_list, merge_bio; 1447 unsigned int segs, offset; 1448 int pending, size; 1449 struct split_bio *split_bio; 1450 struct list_head requests; 1451 1452 /* Stage 1: Make a safe copy of the shadow state. */ 1453 copy = kmemdup(info->shadow, sizeof(info->shadow), 1454 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); 1455 if (!copy) 1456 return -ENOMEM; 1457 1458 /* Stage 2: Set up free list. */ 1459 memset(&info->shadow, 0, sizeof(info->shadow)); 1460 for (i = 0; i < BLK_RING_SIZE; i++) 1461 info->shadow[i].req.u.rw.id = i+1; 1462 info->shadow_free = info->ring.req_prod_pvt; 1463 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1464 1465 rc = blkfront_setup_indirect(info); 1466 if (rc) { 1467 kfree(copy); 1468 return rc; 1469 } 1470 1471 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 1472 blk_queue_max_segments(info->rq, segs); 1473 bio_list_init(&bio_list); 1474 INIT_LIST_HEAD(&requests); 1475 for (i = 0; i < BLK_RING_SIZE; i++) { 1476 /* Not in use? */ 1477 if (!copy[i].request) 1478 continue; 1479 1480 /* 1481 * Get the bios in the request so we can re-queue them. 1482 */ 1483 if (copy[i].request->cmd_flags & 1484 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1485 /* 1486 * Flush operations don't contain bios, so 1487 * we need to requeue the whole request 1488 */ 1489 list_add(©[i].request->queuelist, &requests); 1490 continue; 1491 } 1492 merge_bio.head = copy[i].request->bio; 1493 merge_bio.tail = copy[i].request->biotail; 1494 bio_list_merge(&bio_list, &merge_bio); 1495 copy[i].request->bio = NULL; 1496 blk_put_request(copy[i].request); 1497 } 1498 1499 kfree(copy); 1500 1501 /* 1502 * Empty the queue, this is important because we might have 1503 * requests in the queue with more segments than what we 1504 * can handle now. 1505 */ 1506 spin_lock_irq(&info->io_lock); 1507 while ((req = blk_fetch_request(info->rq)) != NULL) { 1508 if (req->cmd_flags & 1509 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1510 list_add(&req->queuelist, &requests); 1511 continue; 1512 } 1513 merge_bio.head = req->bio; 1514 merge_bio.tail = req->biotail; 1515 bio_list_merge(&bio_list, &merge_bio); 1516 req->bio = NULL; 1517 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) 1518 pr_alert("diskcache flush request found!\n"); 1519 __blk_put_request(info->rq, req); 1520 } 1521 spin_unlock_irq(&info->io_lock); 1522 1523 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1524 1525 spin_lock_irq(&info->io_lock); 1526 1527 /* Now safe for us to use the shared ring */ 1528 info->connected = BLKIF_STATE_CONNECTED; 1529 1530 /* Kick any other new requests queued since we resumed */ 1531 kick_pending_request_queues(info); 1532 1533 list_for_each_entry_safe(req, n, &requests, queuelist) { 1534 /* Requeue pending requests (flush or discard) */ 1535 list_del_init(&req->queuelist); 1536 BUG_ON(req->nr_phys_segments > segs); 1537 blk_requeue_request(info->rq, req); 1538 } 1539 spin_unlock_irq(&info->io_lock); 1540 1541 while ((bio = bio_list_pop(&bio_list)) != NULL) { 1542 /* Traverse the list of pending bios and re-queue them */ 1543 if (bio_segments(bio) > segs) { 1544 /* 1545 * This bio has more segments than what we can 1546 * handle, we have to split it. 1547 */ 1548 pending = (bio_segments(bio) + segs - 1) / segs; 1549 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO); 1550 BUG_ON(split_bio == NULL); 1551 atomic_set(&split_bio->pending, pending); 1552 split_bio->bio = bio; 1553 for (i = 0; i < pending; i++) { 1554 offset = (i * segs * PAGE_SIZE) >> 9; 1555 size = min((unsigned int)(segs * PAGE_SIZE) >> 9, 1556 (unsigned int)bio_sectors(bio) - offset); 1557 cloned_bio = bio_clone(bio, GFP_NOIO); 1558 BUG_ON(cloned_bio == NULL); 1559 bio_trim(cloned_bio, offset, size); 1560 cloned_bio->bi_private = split_bio; 1561 cloned_bio->bi_end_io = split_bio_end; 1562 submit_bio(cloned_bio->bi_rw, cloned_bio); 1563 } 1564 /* 1565 * Now we have to wait for all those smaller bios to 1566 * end, so we can also end the "parent" bio. 1567 */ 1568 continue; 1569 } 1570 /* We don't need to split this bio */ 1571 submit_bio(bio->bi_rw, bio); 1572 } 1573 1574 return 0; 1575} 1576 1577/** 1578 * We are reconnecting to the backend, due to a suspend/resume, or a backend 1579 * driver restart. We tear down our blkif structure and recreate it, but 1580 * leave the device-layer structures intact so that this is transparent to the 1581 * rest of the kernel. 1582 */ 1583static int blkfront_resume(struct xenbus_device *dev) 1584{ 1585 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1586 int err; 1587 1588 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 1589 1590 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 1591 1592 err = talk_to_blkback(dev, info); 1593 1594 /* 1595 * We have to wait for the backend to switch to 1596 * connected state, since we want to read which 1597 * features it supports. 1598 */ 1599 1600 return err; 1601} 1602 1603static void 1604blkfront_closing(struct blkfront_info *info) 1605{ 1606 struct xenbus_device *xbdev = info->xbdev; 1607 struct block_device *bdev = NULL; 1608 1609 mutex_lock(&info->mutex); 1610 1611 if (xbdev->state == XenbusStateClosing) { 1612 mutex_unlock(&info->mutex); 1613 return; 1614 } 1615 1616 if (info->gd) 1617 bdev = bdget_disk(info->gd, 0); 1618 1619 mutex_unlock(&info->mutex); 1620 1621 if (!bdev) { 1622 xenbus_frontend_closed(xbdev); 1623 return; 1624 } 1625 1626 mutex_lock(&bdev->bd_mutex); 1627 1628 if (bdev->bd_openers) { 1629 xenbus_dev_error(xbdev, -EBUSY, 1630 "Device in use; refusing to close"); 1631 xenbus_switch_state(xbdev, XenbusStateClosing); 1632 } else { 1633 xlvbd_release_gendisk(info); 1634 xenbus_frontend_closed(xbdev); 1635 } 1636 1637 mutex_unlock(&bdev->bd_mutex); 1638 bdput(bdev); 1639} 1640 1641static void blkfront_setup_discard(struct blkfront_info *info) 1642{ 1643 int err; 1644 unsigned int discard_granularity; 1645 unsigned int discard_alignment; 1646 unsigned int discard_secure; 1647 1648 info->feature_discard = 1; 1649 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1650 "discard-granularity", "%u", &discard_granularity, 1651 "discard-alignment", "%u", &discard_alignment, 1652 NULL); 1653 if (!err) { 1654 info->discard_granularity = discard_granularity; 1655 info->discard_alignment = discard_alignment; 1656 } 1657 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1658 "discard-secure", "%d", &discard_secure, 1659 NULL); 1660 if (!err) 1661 info->feature_secdiscard = !!discard_secure; 1662} 1663 1664static int blkfront_setup_indirect(struct blkfront_info *info) 1665{ 1666 unsigned int indirect_segments, segs; 1667 int err, i; 1668 1669 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1670 "feature-max-indirect-segments", "%u", &indirect_segments, 1671 NULL); 1672 if (err) { 1673 info->max_indirect_segments = 0; 1674 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST; 1675 } else { 1676 info->max_indirect_segments = min(indirect_segments, 1677 xen_blkif_max_segments); 1678 segs = info->max_indirect_segments; 1679 } 1680 1681 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE); 1682 if (err) 1683 goto out_of_memory; 1684 1685 if (!info->feature_persistent && info->max_indirect_segments) { 1686 /* 1687 * We are using indirect descriptors but not persistent 1688 * grants, we need to allocate a set of pages that can be 1689 * used for mapping indirect grefs 1690 */ 1691 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE; 1692 1693 BUG_ON(!list_empty(&info->indirect_pages)); 1694 for (i = 0; i < num; i++) { 1695 struct page *indirect_page = alloc_page(GFP_NOIO); 1696 if (!indirect_page) 1697 goto out_of_memory; 1698 list_add(&indirect_page->lru, &info->indirect_pages); 1699 } 1700 } 1701 1702 for (i = 0; i < BLK_RING_SIZE; i++) { 1703 info->shadow[i].grants_used = kzalloc( 1704 sizeof(info->shadow[i].grants_used[0]) * segs, 1705 GFP_NOIO); 1706 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO); 1707 if (info->max_indirect_segments) 1708 info->shadow[i].indirect_grants = kzalloc( 1709 sizeof(info->shadow[i].indirect_grants[0]) * 1710 INDIRECT_GREFS(segs), 1711 GFP_NOIO); 1712 if ((info->shadow[i].grants_used == NULL) || 1713 (info->shadow[i].sg == NULL) || 1714 (info->max_indirect_segments && 1715 (info->shadow[i].indirect_grants == NULL))) 1716 goto out_of_memory; 1717 sg_init_table(info->shadow[i].sg, segs); 1718 } 1719 1720 1721 return 0; 1722 1723out_of_memory: 1724 for (i = 0; i < BLK_RING_SIZE; i++) { 1725 kfree(info->shadow[i].grants_used); 1726 info->shadow[i].grants_used = NULL; 1727 kfree(info->shadow[i].sg); 1728 info->shadow[i].sg = NULL; 1729 kfree(info->shadow[i].indirect_grants); 1730 info->shadow[i].indirect_grants = NULL; 1731 } 1732 if (!list_empty(&info->indirect_pages)) { 1733 struct page *indirect_page, *n; 1734 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 1735 list_del(&indirect_page->lru); 1736 __free_page(indirect_page); 1737 } 1738 } 1739 return -ENOMEM; 1740} 1741 1742/* 1743 * Invoked when the backend is finally 'ready' (and has told produced 1744 * the details about the physical device - #sectors, size, etc). 1745 */ 1746static void blkfront_connect(struct blkfront_info *info) 1747{ 1748 unsigned long long sectors; 1749 unsigned long sector_size; 1750 unsigned int physical_sector_size; 1751 unsigned int binfo; 1752 int err; 1753 int barrier, flush, discard, persistent; 1754 1755 switch (info->connected) { 1756 case BLKIF_STATE_CONNECTED: 1757 /* 1758 * Potentially, the back-end may be signalling 1759 * a capacity change; update the capacity. 1760 */ 1761 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1762 "sectors", "%Lu", §ors); 1763 if (XENBUS_EXIST_ERR(err)) 1764 return; 1765 printk(KERN_INFO "Setting capacity to %Lu\n", 1766 sectors); 1767 set_capacity(info->gd, sectors); 1768 revalidate_disk(info->gd); 1769 1770 return; 1771 case BLKIF_STATE_SUSPENDED: 1772 /* 1773 * If we are recovering from suspension, we need to wait 1774 * for the backend to announce it's features before 1775 * reconnecting, at least we need to know if the backend 1776 * supports indirect descriptors, and how many. 1777 */ 1778 blkif_recover(info); 1779 return; 1780 1781 default: 1782 break; 1783 } 1784 1785 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 1786 __func__, info->xbdev->otherend); 1787 1788 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1789 "sectors", "%llu", §ors, 1790 "info", "%u", &binfo, 1791 "sector-size", "%lu", §or_size, 1792 NULL); 1793 if (err) { 1794 xenbus_dev_fatal(info->xbdev, err, 1795 "reading backend fields at %s", 1796 info->xbdev->otherend); 1797 return; 1798 } 1799 1800 /* 1801 * physcial-sector-size is a newer field, so old backends may not 1802 * provide this. Assume physical sector size to be the same as 1803 * sector_size in that case. 1804 */ 1805 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1806 "physical-sector-size", "%u", &physical_sector_size); 1807 if (err != 1) 1808 physical_sector_size = sector_size; 1809 1810 info->feature_flush = 0; 1811 info->flush_op = 0; 1812 1813 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1814 "feature-barrier", "%d", &barrier, 1815 NULL); 1816 1817 /* 1818 * If there's no "feature-barrier" defined, then it means 1819 * we're dealing with a very old backend which writes 1820 * synchronously; nothing to do. 1821 * 1822 * If there are barriers, then we use flush. 1823 */ 1824 if (!err && barrier) { 1825 info->feature_flush = REQ_FLUSH | REQ_FUA; 1826 info->flush_op = BLKIF_OP_WRITE_BARRIER; 1827 } 1828 /* 1829 * And if there is "feature-flush-cache" use that above 1830 * barriers. 1831 */ 1832 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1833 "feature-flush-cache", "%d", &flush, 1834 NULL); 1835 1836 if (!err && flush) { 1837 info->feature_flush = REQ_FLUSH; 1838 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE; 1839 } 1840 1841 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1842 "feature-discard", "%d", &discard, 1843 NULL); 1844 1845 if (!err && discard) 1846 blkfront_setup_discard(info); 1847 1848 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1849 "feature-persistent", "%u", &persistent, 1850 NULL); 1851 if (err) 1852 info->feature_persistent = 0; 1853 else 1854 info->feature_persistent = persistent; 1855 1856 err = blkfront_setup_indirect(info); 1857 if (err) { 1858 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 1859 info->xbdev->otherend); 1860 return; 1861 } 1862 1863 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 1864 physical_sector_size); 1865 if (err) { 1866 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 1867 info->xbdev->otherend); 1868 return; 1869 } 1870 1871 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1872 1873 /* Kick pending requests. */ 1874 spin_lock_irq(&info->io_lock); 1875 info->connected = BLKIF_STATE_CONNECTED; 1876 kick_pending_request_queues(info); 1877 spin_unlock_irq(&info->io_lock); 1878 1879 add_disk(info->gd); 1880 1881 info->is_ready = 1; 1882} 1883 1884/** 1885 * Callback received when the backend's state changes. 1886 */ 1887static void blkback_changed(struct xenbus_device *dev, 1888 enum xenbus_state backend_state) 1889{ 1890 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1891 1892 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 1893 1894 switch (backend_state) { 1895 case XenbusStateInitialising: 1896 case XenbusStateInitWait: 1897 case XenbusStateInitialised: 1898 case XenbusStateReconfiguring: 1899 case XenbusStateReconfigured: 1900 case XenbusStateUnknown: 1901 break; 1902 1903 case XenbusStateConnected: 1904 blkfront_connect(info); 1905 break; 1906 1907 case XenbusStateClosed: 1908 if (dev->state == XenbusStateClosed) 1909 break; 1910 /* Missed the backend's Closing state -- fallthrough */ 1911 case XenbusStateClosing: 1912 blkfront_closing(info); 1913 break; 1914 } 1915} 1916 1917static int blkfront_remove(struct xenbus_device *xbdev) 1918{ 1919 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 1920 struct block_device *bdev = NULL; 1921 struct gendisk *disk; 1922 1923 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 1924 1925 blkif_free(info, 0); 1926 1927 mutex_lock(&info->mutex); 1928 1929 disk = info->gd; 1930 if (disk) 1931 bdev = bdget_disk(disk, 0); 1932 1933 info->xbdev = NULL; 1934 mutex_unlock(&info->mutex); 1935 1936 if (!bdev) { 1937 kfree(info); 1938 return 0; 1939 } 1940 1941 /* 1942 * The xbdev was removed before we reached the Closed 1943 * state. See if it's safe to remove the disk. If the bdev 1944 * isn't closed yet, we let release take care of it. 1945 */ 1946 1947 mutex_lock(&bdev->bd_mutex); 1948 info = disk->private_data; 1949 1950 dev_warn(disk_to_dev(disk), 1951 "%s was hot-unplugged, %d stale handles\n", 1952 xbdev->nodename, bdev->bd_openers); 1953 1954 if (info && !bdev->bd_openers) { 1955 xlvbd_release_gendisk(info); 1956 disk->private_data = NULL; 1957 kfree(info); 1958 } 1959 1960 mutex_unlock(&bdev->bd_mutex); 1961 bdput(bdev); 1962 1963 return 0; 1964} 1965 1966static int blkfront_is_ready(struct xenbus_device *dev) 1967{ 1968 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1969 1970 return info->is_ready && info->xbdev; 1971} 1972 1973static int blkif_open(struct block_device *bdev, fmode_t mode) 1974{ 1975 struct gendisk *disk = bdev->bd_disk; 1976 struct blkfront_info *info; 1977 int err = 0; 1978 1979 mutex_lock(&blkfront_mutex); 1980 1981 info = disk->private_data; 1982 if (!info) { 1983 /* xbdev gone */ 1984 err = -ERESTARTSYS; 1985 goto out; 1986 } 1987 1988 mutex_lock(&info->mutex); 1989 1990 if (!info->gd) 1991 /* xbdev is closed */ 1992 err = -ERESTARTSYS; 1993 1994 mutex_unlock(&info->mutex); 1995 1996out: 1997 mutex_unlock(&blkfront_mutex); 1998 return err; 1999} 2000 2001static void blkif_release(struct gendisk *disk, fmode_t mode) 2002{ 2003 struct blkfront_info *info = disk->private_data; 2004 struct block_device *bdev; 2005 struct xenbus_device *xbdev; 2006 2007 mutex_lock(&blkfront_mutex); 2008 2009 bdev = bdget_disk(disk, 0); 2010 2011 if (!bdev) { 2012 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2013 goto out_mutex; 2014 } 2015 if (bdev->bd_openers) 2016 goto out; 2017 2018 /* 2019 * Check if we have been instructed to close. We will have 2020 * deferred this request, because the bdev was still open. 2021 */ 2022 2023 mutex_lock(&info->mutex); 2024 xbdev = info->xbdev; 2025 2026 if (xbdev && xbdev->state == XenbusStateClosing) { 2027 /* pending switch to state closed */ 2028 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2029 xlvbd_release_gendisk(info); 2030 xenbus_frontend_closed(info->xbdev); 2031 } 2032 2033 mutex_unlock(&info->mutex); 2034 2035 if (!xbdev) { 2036 /* sudden device removal */ 2037 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2038 xlvbd_release_gendisk(info); 2039 disk->private_data = NULL; 2040 kfree(info); 2041 } 2042 2043out: 2044 bdput(bdev); 2045out_mutex: 2046 mutex_unlock(&blkfront_mutex); 2047} 2048 2049static const struct block_device_operations xlvbd_block_fops = 2050{ 2051 .owner = THIS_MODULE, 2052 .open = blkif_open, 2053 .release = blkif_release, 2054 .getgeo = blkif_getgeo, 2055 .ioctl = blkif_ioctl, 2056}; 2057 2058 2059static const struct xenbus_device_id blkfront_ids[] = { 2060 { "vbd" }, 2061 { "" } 2062}; 2063 2064static struct xenbus_driver blkfront_driver = { 2065 .ids = blkfront_ids, 2066 .probe = blkfront_probe, 2067 .remove = blkfront_remove, 2068 .resume = blkfront_resume, 2069 .otherend_changed = blkback_changed, 2070 .is_ready = blkfront_is_ready, 2071}; 2072 2073static int __init xlblk_init(void) 2074{ 2075 int ret; 2076 2077 if (!xen_domain()) 2078 return -ENODEV; 2079 2080 if (!xen_has_pv_disk_devices()) 2081 return -ENODEV; 2082 2083 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2084 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2085 XENVBD_MAJOR, DEV_NAME); 2086 return -ENODEV; 2087 } 2088 2089 ret = xenbus_register_frontend(&blkfront_driver); 2090 if (ret) { 2091 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2092 return ret; 2093 } 2094 2095 return 0; 2096} 2097module_init(xlblk_init); 2098 2099 2100static void __exit xlblk_exit(void) 2101{ 2102 xenbus_unregister_driver(&blkfront_driver); 2103 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2104 kfree(minors); 2105} 2106module_exit(xlblk_exit); 2107 2108MODULE_DESCRIPTION("Xen virtual block device frontend"); 2109MODULE_LICENSE("GPL"); 2110MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2111MODULE_ALIAS("xen:vbd"); 2112MODULE_ALIAS("xenblk"); 2113