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 62 enum blkif_state { 63 BLKIF_STATE_DISCONNECTED, 64 BLKIF_STATE_CONNECTED, 65 BLKIF_STATE_SUSPENDED, 66 }; 67 68 struct grant { 69 grant_ref_t gref; 70 unsigned long pfn; 71 struct list_head node; 72 }; 73 74 struct 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 82 struct split_bio { 83 struct bio *bio; 84 atomic_t pending; 85 int err; 86 }; 87 88 static DEFINE_MUTEX(blkfront_mutex); 89 static 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 97 static unsigned int xen_blkif_max_segments = 32; 98 module_param_named(max, xen_blkif_max_segments, int, S_IRUGO); 99 MODULE_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 */ 108 struct 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 feature_discard:1; 130 unsigned int feature_secdiscard:1; 131 unsigned int discard_granularity; 132 unsigned int discard_alignment; 133 unsigned int feature_persistent:1; 134 unsigned int max_indirect_segments; 135 int is_ready; 136 }; 137 138 static unsigned int nr_minors; 139 static unsigned long *minors; 140 static DEFINE_SPINLOCK(minor_lock); 141 142 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \ 143 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE) 144 #define GRANT_INVALID_REF 0 145 146 #define PARTS_PER_DISK 16 147 #define PARTS_PER_EXT_DISK 256 148 149 #define BLKIF_MAJOR(dev) ((dev)>>8) 150 #define BLKIF_MINOR(dev) ((dev) & 0xff) 151 152 #define EXT_SHIFT 28 153 #define EXTENDED (1<<EXT_SHIFT) 154 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 155 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 156 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 157 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 158 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 159 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 160 161 #define DEV_NAME "xvd" /* name in /dev */ 162 163 #define SEGS_PER_INDIRECT_FRAME \ 164 (PAGE_SIZE/sizeof(struct blkif_request_segment)) 165 #define INDIRECT_GREFS(_segs) \ 166 ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME) 167 168 static int blkfront_setup_indirect(struct blkfront_info *info); 169 170 static int get_id_from_freelist(struct blkfront_info *info) 171 { 172 unsigned long free = info->shadow_free; 173 BUG_ON(free >= BLK_RING_SIZE); 174 info->shadow_free = info->shadow[free].req.u.rw.id; 175 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 176 return free; 177 } 178 179 static int add_id_to_freelist(struct blkfront_info *info, 180 unsigned long id) 181 { 182 if (info->shadow[id].req.u.rw.id != id) 183 return -EINVAL; 184 if (info->shadow[id].request == NULL) 185 return -EINVAL; 186 info->shadow[id].req.u.rw.id = info->shadow_free; 187 info->shadow[id].request = NULL; 188 info->shadow_free = id; 189 return 0; 190 } 191 192 static int fill_grant_buffer(struct blkfront_info *info, int num) 193 { 194 struct page *granted_page; 195 struct grant *gnt_list_entry, *n; 196 int i = 0; 197 198 while(i < num) { 199 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 200 if (!gnt_list_entry) 201 goto out_of_memory; 202 203 if (info->feature_persistent) { 204 granted_page = alloc_page(GFP_NOIO); 205 if (!granted_page) { 206 kfree(gnt_list_entry); 207 goto out_of_memory; 208 } 209 gnt_list_entry->pfn = page_to_pfn(granted_page); 210 } 211 212 gnt_list_entry->gref = GRANT_INVALID_REF; 213 list_add(&gnt_list_entry->node, &info->grants); 214 i++; 215 } 216 217 return 0; 218 219 out_of_memory: 220 list_for_each_entry_safe(gnt_list_entry, n, 221 &info->grants, node) { 222 list_del(&gnt_list_entry->node); 223 if (info->feature_persistent) 224 __free_page(pfn_to_page(gnt_list_entry->pfn)); 225 kfree(gnt_list_entry); 226 i--; 227 } 228 BUG_ON(i != 0); 229 return -ENOMEM; 230 } 231 232 static struct grant *get_grant(grant_ref_t *gref_head, 233 unsigned long pfn, 234 struct blkfront_info *info) 235 { 236 struct grant *gnt_list_entry; 237 unsigned long buffer_mfn; 238 239 BUG_ON(list_empty(&info->grants)); 240 gnt_list_entry = list_first_entry(&info->grants, struct grant, 241 node); 242 list_del(&gnt_list_entry->node); 243 244 if (gnt_list_entry->gref != GRANT_INVALID_REF) { 245 info->persistent_gnts_c--; 246 return gnt_list_entry; 247 } 248 249 /* Assign a gref to this page */ 250 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 251 BUG_ON(gnt_list_entry->gref == -ENOSPC); 252 if (!info->feature_persistent) { 253 BUG_ON(!pfn); 254 gnt_list_entry->pfn = pfn; 255 } 256 buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); 257 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 258 info->xbdev->otherend_id, 259 buffer_mfn, 0); 260 return gnt_list_entry; 261 } 262 263 static const char *op_name(int op) 264 { 265 static const char *const names[] = { 266 [BLKIF_OP_READ] = "read", 267 [BLKIF_OP_WRITE] = "write", 268 [BLKIF_OP_WRITE_BARRIER] = "barrier", 269 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 270 [BLKIF_OP_DISCARD] = "discard" }; 271 272 if (op < 0 || op >= ARRAY_SIZE(names)) 273 return "unknown"; 274 275 if (!names[op]) 276 return "reserved"; 277 278 return names[op]; 279 } 280 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 281 { 282 unsigned int end = minor + nr; 283 int rc; 284 285 if (end > nr_minors) { 286 unsigned long *bitmap, *old; 287 288 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 289 GFP_KERNEL); 290 if (bitmap == NULL) 291 return -ENOMEM; 292 293 spin_lock(&minor_lock); 294 if (end > nr_minors) { 295 old = minors; 296 memcpy(bitmap, minors, 297 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 298 minors = bitmap; 299 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 300 } else 301 old = bitmap; 302 spin_unlock(&minor_lock); 303 kfree(old); 304 } 305 306 spin_lock(&minor_lock); 307 if (find_next_bit(minors, end, minor) >= end) { 308 bitmap_set(minors, minor, nr); 309 rc = 0; 310 } else 311 rc = -EBUSY; 312 spin_unlock(&minor_lock); 313 314 return rc; 315 } 316 317 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 318 { 319 unsigned int end = minor + nr; 320 321 BUG_ON(end > nr_minors); 322 spin_lock(&minor_lock); 323 bitmap_clear(minors, minor, nr); 324 spin_unlock(&minor_lock); 325 } 326 327 static void blkif_restart_queue_callback(void *arg) 328 { 329 struct blkfront_info *info = (struct blkfront_info *)arg; 330 schedule_work(&info->work); 331 } 332 333 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 334 { 335 /* We don't have real geometry info, but let's at least return 336 values consistent with the size of the device */ 337 sector_t nsect = get_capacity(bd->bd_disk); 338 sector_t cylinders = nsect; 339 340 hg->heads = 0xff; 341 hg->sectors = 0x3f; 342 sector_div(cylinders, hg->heads * hg->sectors); 343 hg->cylinders = cylinders; 344 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 345 hg->cylinders = 0xffff; 346 return 0; 347 } 348 349 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 350 unsigned command, unsigned long argument) 351 { 352 struct blkfront_info *info = bdev->bd_disk->private_data; 353 int i; 354 355 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 356 command, (long)argument); 357 358 switch (command) { 359 case CDROMMULTISESSION: 360 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 361 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 362 if (put_user(0, (char __user *)(argument + i))) 363 return -EFAULT; 364 return 0; 365 366 case CDROM_GET_CAPABILITY: { 367 struct gendisk *gd = info->gd; 368 if (gd->flags & GENHD_FL_CD) 369 return 0; 370 return -EINVAL; 371 } 372 373 default: 374 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 375 command);*/ 376 return -EINVAL; /* same return as native Linux */ 377 } 378 379 return 0; 380 } 381 382 /* 383 * Generate a Xen blkfront IO request from a blk layer request. Reads 384 * and writes are handled as expected. 385 * 386 * @req: a request struct 387 */ 388 static int blkif_queue_request(struct request *req) 389 { 390 struct blkfront_info *info = req->rq_disk->private_data; 391 struct blkif_request *ring_req; 392 unsigned long id; 393 unsigned int fsect, lsect; 394 int i, ref, n; 395 struct blkif_request_segment *segments = NULL; 396 397 /* 398 * Used to store if we are able to queue the request by just using 399 * existing persistent grants, or if we have to get new grants, 400 * as there are not sufficiently many free. 401 */ 402 bool new_persistent_gnts; 403 grant_ref_t gref_head; 404 struct grant *gnt_list_entry = NULL; 405 struct scatterlist *sg; 406 int nseg, max_grefs; 407 408 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 409 return 1; 410 411 max_grefs = req->nr_phys_segments; 412 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 413 /* 414 * If we are using indirect segments we need to account 415 * for the indirect grefs used in the request. 416 */ 417 max_grefs += INDIRECT_GREFS(req->nr_phys_segments); 418 419 /* Check if we have enough grants to allocate a requests */ 420 if (info->persistent_gnts_c < max_grefs) { 421 new_persistent_gnts = 1; 422 if (gnttab_alloc_grant_references( 423 max_grefs - info->persistent_gnts_c, 424 &gref_head) < 0) { 425 gnttab_request_free_callback( 426 &info->callback, 427 blkif_restart_queue_callback, 428 info, 429 max_grefs); 430 return 1; 431 } 432 } else 433 new_persistent_gnts = 0; 434 435 /* Fill out a communications ring structure. */ 436 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); 437 id = get_id_from_freelist(info); 438 info->shadow[id].request = req; 439 440 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) { 441 ring_req->operation = BLKIF_OP_DISCARD; 442 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 443 ring_req->u.discard.id = id; 444 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 445 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) 446 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 447 else 448 ring_req->u.discard.flag = 0; 449 } else { 450 BUG_ON(info->max_indirect_segments == 0 && 451 req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST); 452 BUG_ON(info->max_indirect_segments && 453 req->nr_phys_segments > info->max_indirect_segments); 454 nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg); 455 ring_req->u.rw.id = id; 456 if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) { 457 /* 458 * The indirect operation can only be a BLKIF_OP_READ or 459 * BLKIF_OP_WRITE 460 */ 461 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA)); 462 ring_req->operation = BLKIF_OP_INDIRECT; 463 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 464 BLKIF_OP_WRITE : BLKIF_OP_READ; 465 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 466 ring_req->u.indirect.handle = info->handle; 467 ring_req->u.indirect.nr_segments = nseg; 468 } else { 469 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 470 ring_req->u.rw.handle = info->handle; 471 ring_req->operation = rq_data_dir(req) ? 472 BLKIF_OP_WRITE : BLKIF_OP_READ; 473 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { 474 /* 475 * Ideally we can do an unordered flush-to-disk. In case the 476 * backend onlysupports barriers, use that. A barrier request 477 * a superset of FUA, so we can implement it the same 478 * way. (It's also a FLUSH+FUA, since it is 479 * guaranteed ordered WRT previous writes.) 480 */ 481 switch (info->feature_flush & 482 ((REQ_FLUSH|REQ_FUA))) { 483 case REQ_FLUSH|REQ_FUA: 484 ring_req->operation = 485 BLKIF_OP_WRITE_BARRIER; 486 break; 487 case REQ_FLUSH: 488 ring_req->operation = 489 BLKIF_OP_FLUSH_DISKCACHE; 490 break; 491 default: 492 ring_req->operation = 0; 493 } 494 } 495 ring_req->u.rw.nr_segments = nseg; 496 } 497 for_each_sg(info->shadow[id].sg, sg, nseg, i) { 498 fsect = sg->offset >> 9; 499 lsect = fsect + (sg->length >> 9) - 1; 500 501 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 502 (i % SEGS_PER_INDIRECT_FRAME == 0)) { 503 unsigned long uninitialized_var(pfn); 504 505 if (segments) 506 kunmap_atomic(segments); 507 508 n = i / SEGS_PER_INDIRECT_FRAME; 509 if (!info->feature_persistent) { 510 struct page *indirect_page; 511 512 /* Fetch a pre-allocated page to use for indirect grefs */ 513 BUG_ON(list_empty(&info->indirect_pages)); 514 indirect_page = list_first_entry(&info->indirect_pages, 515 struct page, lru); 516 list_del(&indirect_page->lru); 517 pfn = page_to_pfn(indirect_page); 518 } 519 gnt_list_entry = get_grant(&gref_head, pfn, info); 520 info->shadow[id].indirect_grants[n] = gnt_list_entry; 521 segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); 522 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 523 } 524 525 gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info); 526 ref = gnt_list_entry->gref; 527 528 info->shadow[id].grants_used[i] = gnt_list_entry; 529 530 if (rq_data_dir(req) && info->feature_persistent) { 531 char *bvec_data; 532 void *shared_data; 533 534 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 535 536 shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); 537 bvec_data = kmap_atomic(sg_page(sg)); 538 539 /* 540 * this does not wipe data stored outside the 541 * range sg->offset..sg->offset+sg->length. 542 * Therefore, blkback *could* see data from 543 * previous requests. This is OK as long as 544 * persistent grants are shared with just one 545 * domain. It may need refactoring if this 546 * changes 547 */ 548 memcpy(shared_data + sg->offset, 549 bvec_data + sg->offset, 550 sg->length); 551 552 kunmap_atomic(bvec_data); 553 kunmap_atomic(shared_data); 554 } 555 if (ring_req->operation != BLKIF_OP_INDIRECT) { 556 ring_req->u.rw.seg[i] = 557 (struct blkif_request_segment) { 558 .gref = ref, 559 .first_sect = fsect, 560 .last_sect = lsect }; 561 } else { 562 n = i % SEGS_PER_INDIRECT_FRAME; 563 segments[n] = 564 (struct blkif_request_segment) { 565 .gref = ref, 566 .first_sect = fsect, 567 .last_sect = lsect }; 568 } 569 } 570 if (segments) 571 kunmap_atomic(segments); 572 } 573 574 info->ring.req_prod_pvt++; 575 576 /* Keep a private copy so we can reissue requests when recovering. */ 577 info->shadow[id].req = *ring_req; 578 579 if (new_persistent_gnts) 580 gnttab_free_grant_references(gref_head); 581 582 return 0; 583 } 584 585 586 static inline void flush_requests(struct blkfront_info *info) 587 { 588 int notify; 589 590 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); 591 592 if (notify) 593 notify_remote_via_irq(info->irq); 594 } 595 596 static inline bool blkif_request_flush_invalid(struct request *req, 597 struct blkfront_info *info) 598 { 599 return ((req->cmd_type != REQ_TYPE_FS) || 600 ((req->cmd_flags & REQ_FLUSH) && 601 !(info->feature_flush & REQ_FLUSH)) || 602 ((req->cmd_flags & REQ_FUA) && 603 !(info->feature_flush & REQ_FUA))); 604 } 605 606 /* 607 * do_blkif_request 608 * read a block; request is in a request queue 609 */ 610 static void do_blkif_request(struct request_queue *rq) 611 { 612 struct blkfront_info *info = NULL; 613 struct request *req; 614 int queued; 615 616 pr_debug("Entered do_blkif_request\n"); 617 618 queued = 0; 619 620 while ((req = blk_peek_request(rq)) != NULL) { 621 info = req->rq_disk->private_data; 622 623 if (RING_FULL(&info->ring)) 624 goto wait; 625 626 blk_start_request(req); 627 628 if (blkif_request_flush_invalid(req, info)) { 629 __blk_end_request_all(req, -EOPNOTSUPP); 630 continue; 631 } 632 633 pr_debug("do_blk_req %p: cmd %p, sec %lx, " 634 "(%u/%u) [%s]\n", 635 req, req->cmd, (unsigned long)blk_rq_pos(req), 636 blk_rq_cur_sectors(req), blk_rq_sectors(req), 637 rq_data_dir(req) ? "write" : "read"); 638 639 if (blkif_queue_request(req)) { 640 blk_requeue_request(rq, req); 641 wait: 642 /* Avoid pointless unplugs. */ 643 blk_stop_queue(rq); 644 break; 645 } 646 647 queued++; 648 } 649 650 if (queued != 0) 651 flush_requests(info); 652 } 653 654 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, 655 unsigned int physical_sector_size, 656 unsigned int segments) 657 { 658 struct request_queue *rq; 659 struct blkfront_info *info = gd->private_data; 660 661 rq = blk_init_queue(do_blkif_request, &info->io_lock); 662 if (rq == NULL) 663 return -1; 664 665 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 666 667 if (info->feature_discard) { 668 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); 669 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 670 rq->limits.discard_granularity = info->discard_granularity; 671 rq->limits.discard_alignment = info->discard_alignment; 672 if (info->feature_secdiscard) 673 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq); 674 } 675 676 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 677 blk_queue_logical_block_size(rq, sector_size); 678 blk_queue_physical_block_size(rq, physical_sector_size); 679 blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512); 680 681 /* Each segment in a request is up to an aligned page in size. */ 682 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 683 blk_queue_max_segment_size(rq, PAGE_SIZE); 684 685 /* Ensure a merged request will fit in a single I/O ring slot. */ 686 blk_queue_max_segments(rq, segments); 687 688 /* Make sure buffer addresses are sector-aligned. */ 689 blk_queue_dma_alignment(rq, 511); 690 691 /* Make sure we don't use bounce buffers. */ 692 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); 693 694 gd->queue = rq; 695 696 return 0; 697 } 698 699 static const char *flush_info(unsigned int feature_flush) 700 { 701 switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) { 702 case REQ_FLUSH|REQ_FUA: 703 return "barrier: enabled;"; 704 case REQ_FLUSH: 705 return "flush diskcache: enabled;"; 706 default: 707 return "barrier or flush: disabled;"; 708 } 709 } 710 711 static void xlvbd_flush(struct blkfront_info *info) 712 { 713 blk_queue_flush(info->rq, info->feature_flush); 714 pr_info("blkfront: %s: %s %s %s %s %s\n", 715 info->gd->disk_name, flush_info(info->feature_flush), 716 "persistent grants:", info->feature_persistent ? 717 "enabled;" : "disabled;", "indirect descriptors:", 718 info->max_indirect_segments ? "enabled;" : "disabled;"); 719 } 720 721 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 722 { 723 int major; 724 major = BLKIF_MAJOR(vdevice); 725 *minor = BLKIF_MINOR(vdevice); 726 switch (major) { 727 case XEN_IDE0_MAJOR: 728 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 729 *minor = ((*minor / 64) * PARTS_PER_DISK) + 730 EMULATED_HD_DISK_MINOR_OFFSET; 731 break; 732 case XEN_IDE1_MAJOR: 733 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 734 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 735 EMULATED_HD_DISK_MINOR_OFFSET; 736 break; 737 case XEN_SCSI_DISK0_MAJOR: 738 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 739 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 740 break; 741 case XEN_SCSI_DISK1_MAJOR: 742 case XEN_SCSI_DISK2_MAJOR: 743 case XEN_SCSI_DISK3_MAJOR: 744 case XEN_SCSI_DISK4_MAJOR: 745 case XEN_SCSI_DISK5_MAJOR: 746 case XEN_SCSI_DISK6_MAJOR: 747 case XEN_SCSI_DISK7_MAJOR: 748 *offset = (*minor / PARTS_PER_DISK) + 749 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 750 EMULATED_SD_DISK_NAME_OFFSET; 751 *minor = *minor + 752 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 753 EMULATED_SD_DISK_MINOR_OFFSET; 754 break; 755 case XEN_SCSI_DISK8_MAJOR: 756 case XEN_SCSI_DISK9_MAJOR: 757 case XEN_SCSI_DISK10_MAJOR: 758 case XEN_SCSI_DISK11_MAJOR: 759 case XEN_SCSI_DISK12_MAJOR: 760 case XEN_SCSI_DISK13_MAJOR: 761 case XEN_SCSI_DISK14_MAJOR: 762 case XEN_SCSI_DISK15_MAJOR: 763 *offset = (*minor / PARTS_PER_DISK) + 764 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 765 EMULATED_SD_DISK_NAME_OFFSET; 766 *minor = *minor + 767 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 768 EMULATED_SD_DISK_MINOR_OFFSET; 769 break; 770 case XENVBD_MAJOR: 771 *offset = *minor / PARTS_PER_DISK; 772 break; 773 default: 774 printk(KERN_WARNING "blkfront: your disk configuration is " 775 "incorrect, please use an xvd device instead\n"); 776 return -ENODEV; 777 } 778 return 0; 779 } 780 781 static char *encode_disk_name(char *ptr, unsigned int n) 782 { 783 if (n >= 26) 784 ptr = encode_disk_name(ptr, n / 26 - 1); 785 *ptr = 'a' + n % 26; 786 return ptr + 1; 787 } 788 789 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 790 struct blkfront_info *info, 791 u16 vdisk_info, u16 sector_size, 792 unsigned int physical_sector_size) 793 { 794 struct gendisk *gd; 795 int nr_minors = 1; 796 int err; 797 unsigned int offset; 798 int minor; 799 int nr_parts; 800 char *ptr; 801 802 BUG_ON(info->gd != NULL); 803 BUG_ON(info->rq != NULL); 804 805 if ((info->vdevice>>EXT_SHIFT) > 1) { 806 /* this is above the extended range; something is wrong */ 807 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 808 return -ENODEV; 809 } 810 811 if (!VDEV_IS_EXTENDED(info->vdevice)) { 812 err = xen_translate_vdev(info->vdevice, &minor, &offset); 813 if (err) 814 return err; 815 nr_parts = PARTS_PER_DISK; 816 } else { 817 minor = BLKIF_MINOR_EXT(info->vdevice); 818 nr_parts = PARTS_PER_EXT_DISK; 819 offset = minor / nr_parts; 820 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 821 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 822 "emulated IDE disks,\n\t choose an xvd device name" 823 "from xvde on\n", info->vdevice); 824 } 825 if (minor >> MINORBITS) { 826 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 827 info->vdevice, minor); 828 return -ENODEV; 829 } 830 831 if ((minor % nr_parts) == 0) 832 nr_minors = nr_parts; 833 834 err = xlbd_reserve_minors(minor, nr_minors); 835 if (err) 836 goto out; 837 err = -ENODEV; 838 839 gd = alloc_disk(nr_minors); 840 if (gd == NULL) 841 goto release; 842 843 strcpy(gd->disk_name, DEV_NAME); 844 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 845 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 846 if (nr_minors > 1) 847 *ptr = 0; 848 else 849 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 850 "%d", minor & (nr_parts - 1)); 851 852 gd->major = XENVBD_MAJOR; 853 gd->first_minor = minor; 854 gd->fops = &xlvbd_block_fops; 855 gd->private_data = info; 856 gd->driverfs_dev = &(info->xbdev->dev); 857 set_capacity(gd, capacity); 858 859 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size, 860 info->max_indirect_segments ? : 861 BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 862 del_gendisk(gd); 863 goto release; 864 } 865 866 info->rq = gd->queue; 867 info->gd = gd; 868 869 xlvbd_flush(info); 870 871 if (vdisk_info & VDISK_READONLY) 872 set_disk_ro(gd, 1); 873 874 if (vdisk_info & VDISK_REMOVABLE) 875 gd->flags |= GENHD_FL_REMOVABLE; 876 877 if (vdisk_info & VDISK_CDROM) 878 gd->flags |= GENHD_FL_CD; 879 880 return 0; 881 882 release: 883 xlbd_release_minors(minor, nr_minors); 884 out: 885 return err; 886 } 887 888 static void xlvbd_release_gendisk(struct blkfront_info *info) 889 { 890 unsigned int minor, nr_minors; 891 unsigned long flags; 892 893 if (info->rq == NULL) 894 return; 895 896 spin_lock_irqsave(&info->io_lock, flags); 897 898 /* No more blkif_request(). */ 899 blk_stop_queue(info->rq); 900 901 /* No more gnttab callback work. */ 902 gnttab_cancel_free_callback(&info->callback); 903 spin_unlock_irqrestore(&info->io_lock, flags); 904 905 /* Flush gnttab callback work. Must be done with no locks held. */ 906 flush_work(&info->work); 907 908 del_gendisk(info->gd); 909 910 minor = info->gd->first_minor; 911 nr_minors = info->gd->minors; 912 xlbd_release_minors(minor, nr_minors); 913 914 blk_cleanup_queue(info->rq); 915 info->rq = NULL; 916 917 put_disk(info->gd); 918 info->gd = NULL; 919 } 920 921 static void kick_pending_request_queues(struct blkfront_info *info) 922 { 923 if (!RING_FULL(&info->ring)) { 924 /* Re-enable calldowns. */ 925 blk_start_queue(info->rq); 926 /* Kick things off immediately. */ 927 do_blkif_request(info->rq); 928 } 929 } 930 931 static void blkif_restart_queue(struct work_struct *work) 932 { 933 struct blkfront_info *info = container_of(work, struct blkfront_info, work); 934 935 spin_lock_irq(&info->io_lock); 936 if (info->connected == BLKIF_STATE_CONNECTED) 937 kick_pending_request_queues(info); 938 spin_unlock_irq(&info->io_lock); 939 } 940 941 static void blkif_free(struct blkfront_info *info, int suspend) 942 { 943 struct grant *persistent_gnt; 944 struct grant *n; 945 int i, j, segs; 946 947 /* Prevent new requests being issued until we fix things up. */ 948 spin_lock_irq(&info->io_lock); 949 info->connected = suspend ? 950 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 951 /* No more blkif_request(). */ 952 if (info->rq) 953 blk_stop_queue(info->rq); 954 955 /* Remove all persistent grants */ 956 if (!list_empty(&info->grants)) { 957 list_for_each_entry_safe(persistent_gnt, n, 958 &info->grants, node) { 959 list_del(&persistent_gnt->node); 960 if (persistent_gnt->gref != GRANT_INVALID_REF) { 961 gnttab_end_foreign_access(persistent_gnt->gref, 962 0, 0UL); 963 info->persistent_gnts_c--; 964 } 965 if (info->feature_persistent) 966 __free_page(pfn_to_page(persistent_gnt->pfn)); 967 kfree(persistent_gnt); 968 } 969 } 970 BUG_ON(info->persistent_gnts_c != 0); 971 972 /* 973 * Remove indirect pages, this only happens when using indirect 974 * descriptors but not persistent grants 975 */ 976 if (!list_empty(&info->indirect_pages)) { 977 struct page *indirect_page, *n; 978 979 BUG_ON(info->feature_persistent); 980 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 981 list_del(&indirect_page->lru); 982 __free_page(indirect_page); 983 } 984 } 985 986 for (i = 0; i < BLK_RING_SIZE; i++) { 987 /* 988 * Clear persistent grants present in requests already 989 * on the shared ring 990 */ 991 if (!info->shadow[i].request) 992 goto free_shadow; 993 994 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 995 info->shadow[i].req.u.indirect.nr_segments : 996 info->shadow[i].req.u.rw.nr_segments; 997 for (j = 0; j < segs; j++) { 998 persistent_gnt = info->shadow[i].grants_used[j]; 999 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1000 if (info->feature_persistent) 1001 __free_page(pfn_to_page(persistent_gnt->pfn)); 1002 kfree(persistent_gnt); 1003 } 1004 1005 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT) 1006 /* 1007 * If this is not an indirect operation don't try to 1008 * free indirect segments 1009 */ 1010 goto free_shadow; 1011 1012 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 1013 persistent_gnt = info->shadow[i].indirect_grants[j]; 1014 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1015 __free_page(pfn_to_page(persistent_gnt->pfn)); 1016 kfree(persistent_gnt); 1017 } 1018 1019 free_shadow: 1020 kfree(info->shadow[i].grants_used); 1021 info->shadow[i].grants_used = NULL; 1022 kfree(info->shadow[i].indirect_grants); 1023 info->shadow[i].indirect_grants = NULL; 1024 kfree(info->shadow[i].sg); 1025 info->shadow[i].sg = NULL; 1026 } 1027 1028 /* No more gnttab callback work. */ 1029 gnttab_cancel_free_callback(&info->callback); 1030 spin_unlock_irq(&info->io_lock); 1031 1032 /* Flush gnttab callback work. Must be done with no locks held. */ 1033 flush_work(&info->work); 1034 1035 /* Free resources associated with old device channel. */ 1036 if (info->ring_ref != GRANT_INVALID_REF) { 1037 gnttab_end_foreign_access(info->ring_ref, 0, 1038 (unsigned long)info->ring.sring); 1039 info->ring_ref = GRANT_INVALID_REF; 1040 info->ring.sring = NULL; 1041 } 1042 if (info->irq) 1043 unbind_from_irqhandler(info->irq, info); 1044 info->evtchn = info->irq = 0; 1045 1046 } 1047 1048 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, 1049 struct blkif_response *bret) 1050 { 1051 int i = 0; 1052 struct scatterlist *sg; 1053 char *bvec_data; 1054 void *shared_data; 1055 int nseg; 1056 1057 nseg = s->req.operation == BLKIF_OP_INDIRECT ? 1058 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1059 1060 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { 1061 /* 1062 * Copy the data received from the backend into the bvec. 1063 * Since bv_offset can be different than 0, and bv_len different 1064 * than PAGE_SIZE, we have to keep track of the current offset, 1065 * to be sure we are copying the data from the right shared page. 1066 */ 1067 for_each_sg(s->sg, sg, nseg, i) { 1068 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1069 shared_data = kmap_atomic( 1070 pfn_to_page(s->grants_used[i]->pfn)); 1071 bvec_data = kmap_atomic(sg_page(sg)); 1072 memcpy(bvec_data + sg->offset, 1073 shared_data + sg->offset, 1074 sg->length); 1075 kunmap_atomic(bvec_data); 1076 kunmap_atomic(shared_data); 1077 } 1078 } 1079 /* Add the persistent grant into the list of free grants */ 1080 for (i = 0; i < nseg; i++) { 1081 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) { 1082 /* 1083 * If the grant is still mapped by the backend (the 1084 * backend has chosen to make this grant persistent) 1085 * we add it at the head of the list, so it will be 1086 * reused first. 1087 */ 1088 if (!info->feature_persistent) 1089 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1090 s->grants_used[i]->gref); 1091 list_add(&s->grants_used[i]->node, &info->grants); 1092 info->persistent_gnts_c++; 1093 } else { 1094 /* 1095 * If the grant is not mapped by the backend we end the 1096 * foreign access and add it to the tail of the list, 1097 * so it will not be picked again unless we run out of 1098 * persistent grants. 1099 */ 1100 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); 1101 s->grants_used[i]->gref = GRANT_INVALID_REF; 1102 list_add_tail(&s->grants_used[i]->node, &info->grants); 1103 } 1104 } 1105 if (s->req.operation == BLKIF_OP_INDIRECT) { 1106 for (i = 0; i < INDIRECT_GREFS(nseg); i++) { 1107 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { 1108 if (!info->feature_persistent) 1109 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1110 s->indirect_grants[i]->gref); 1111 list_add(&s->indirect_grants[i]->node, &info->grants); 1112 info->persistent_gnts_c++; 1113 } else { 1114 struct page *indirect_page; 1115 1116 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); 1117 /* 1118 * Add the used indirect page back to the list of 1119 * available pages for indirect grefs. 1120 */ 1121 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn); 1122 list_add(&indirect_page->lru, &info->indirect_pages); 1123 s->indirect_grants[i]->gref = GRANT_INVALID_REF; 1124 list_add_tail(&s->indirect_grants[i]->node, &info->grants); 1125 } 1126 } 1127 } 1128 } 1129 1130 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1131 { 1132 struct request *req; 1133 struct blkif_response *bret; 1134 RING_IDX i, rp; 1135 unsigned long flags; 1136 struct blkfront_info *info = (struct blkfront_info *)dev_id; 1137 int error; 1138 1139 spin_lock_irqsave(&info->io_lock, flags); 1140 1141 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { 1142 spin_unlock_irqrestore(&info->io_lock, flags); 1143 return IRQ_HANDLED; 1144 } 1145 1146 again: 1147 rp = info->ring.sring->rsp_prod; 1148 rmb(); /* Ensure we see queued responses up to 'rp'. */ 1149 1150 for (i = info->ring.rsp_cons; i != rp; i++) { 1151 unsigned long id; 1152 1153 bret = RING_GET_RESPONSE(&info->ring, i); 1154 id = bret->id; 1155 /* 1156 * The backend has messed up and given us an id that we would 1157 * never have given to it (we stamp it up to BLK_RING_SIZE - 1158 * look in get_id_from_freelist. 1159 */ 1160 if (id >= BLK_RING_SIZE) { 1161 WARN(1, "%s: response to %s has incorrect id (%ld)\n", 1162 info->gd->disk_name, op_name(bret->operation), id); 1163 /* We can't safely get the 'struct request' as 1164 * the id is busted. */ 1165 continue; 1166 } 1167 req = info->shadow[id].request; 1168 1169 if (bret->operation != BLKIF_OP_DISCARD) 1170 blkif_completion(&info->shadow[id], info, bret); 1171 1172 if (add_id_to_freelist(info, id)) { 1173 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1174 info->gd->disk_name, op_name(bret->operation), id); 1175 continue; 1176 } 1177 1178 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; 1179 switch (bret->operation) { 1180 case BLKIF_OP_DISCARD: 1181 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1182 struct request_queue *rq = info->rq; 1183 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1184 info->gd->disk_name, op_name(bret->operation)); 1185 error = -EOPNOTSUPP; 1186 info->feature_discard = 0; 1187 info->feature_secdiscard = 0; 1188 queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 1189 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq); 1190 } 1191 __blk_end_request_all(req, error); 1192 break; 1193 case BLKIF_OP_FLUSH_DISKCACHE: 1194 case BLKIF_OP_WRITE_BARRIER: 1195 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1196 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1197 info->gd->disk_name, op_name(bret->operation)); 1198 error = -EOPNOTSUPP; 1199 } 1200 if (unlikely(bret->status == BLKIF_RSP_ERROR && 1201 info->shadow[id].req.u.rw.nr_segments == 0)) { 1202 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", 1203 info->gd->disk_name, op_name(bret->operation)); 1204 error = -EOPNOTSUPP; 1205 } 1206 if (unlikely(error)) { 1207 if (error == -EOPNOTSUPP) 1208 error = 0; 1209 info->feature_flush = 0; 1210 xlvbd_flush(info); 1211 } 1212 /* fall through */ 1213 case BLKIF_OP_READ: 1214 case BLKIF_OP_WRITE: 1215 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 1216 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 1217 "request: %x\n", bret->status); 1218 1219 __blk_end_request_all(req, error); 1220 break; 1221 default: 1222 BUG(); 1223 } 1224 } 1225 1226 info->ring.rsp_cons = i; 1227 1228 if (i != info->ring.req_prod_pvt) { 1229 int more_to_do; 1230 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 1231 if (more_to_do) 1232 goto again; 1233 } else 1234 info->ring.sring->rsp_event = i + 1; 1235 1236 kick_pending_request_queues(info); 1237 1238 spin_unlock_irqrestore(&info->io_lock, flags); 1239 1240 return IRQ_HANDLED; 1241 } 1242 1243 1244 static int setup_blkring(struct xenbus_device *dev, 1245 struct blkfront_info *info) 1246 { 1247 struct blkif_sring *sring; 1248 grant_ref_t gref; 1249 int err; 1250 1251 info->ring_ref = GRANT_INVALID_REF; 1252 1253 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH); 1254 if (!sring) { 1255 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1256 return -ENOMEM; 1257 } 1258 SHARED_RING_INIT(sring); 1259 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 1260 1261 err = xenbus_grant_ring(dev, info->ring.sring, 1, &gref); 1262 if (err < 0) { 1263 free_page((unsigned long)sring); 1264 info->ring.sring = NULL; 1265 goto fail; 1266 } 1267 info->ring_ref = gref; 1268 1269 err = xenbus_alloc_evtchn(dev, &info->evtchn); 1270 if (err) 1271 goto fail; 1272 1273 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0, 1274 "blkif", info); 1275 if (err <= 0) { 1276 xenbus_dev_fatal(dev, err, 1277 "bind_evtchn_to_irqhandler failed"); 1278 goto fail; 1279 } 1280 info->irq = err; 1281 1282 return 0; 1283 fail: 1284 blkif_free(info, 0); 1285 return err; 1286 } 1287 1288 1289 /* Common code used when first setting up, and when resuming. */ 1290 static int talk_to_blkback(struct xenbus_device *dev, 1291 struct blkfront_info *info) 1292 { 1293 const char *message = NULL; 1294 struct xenbus_transaction xbt; 1295 int err; 1296 1297 /* Create shared ring, alloc event channel. */ 1298 err = setup_blkring(dev, info); 1299 if (err) 1300 goto out; 1301 1302 again: 1303 err = xenbus_transaction_start(&xbt); 1304 if (err) { 1305 xenbus_dev_fatal(dev, err, "starting transaction"); 1306 goto destroy_blkring; 1307 } 1308 1309 err = xenbus_printf(xbt, dev->nodename, 1310 "ring-ref", "%u", info->ring_ref); 1311 if (err) { 1312 message = "writing ring-ref"; 1313 goto abort_transaction; 1314 } 1315 err = xenbus_printf(xbt, dev->nodename, 1316 "event-channel", "%u", info->evtchn); 1317 if (err) { 1318 message = "writing event-channel"; 1319 goto abort_transaction; 1320 } 1321 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1322 XEN_IO_PROTO_ABI_NATIVE); 1323 if (err) { 1324 message = "writing protocol"; 1325 goto abort_transaction; 1326 } 1327 err = xenbus_printf(xbt, dev->nodename, 1328 "feature-persistent", "%u", 1); 1329 if (err) 1330 dev_warn(&dev->dev, 1331 "writing persistent grants feature to xenbus"); 1332 1333 err = xenbus_transaction_end(xbt, 0); 1334 if (err) { 1335 if (err == -EAGAIN) 1336 goto again; 1337 xenbus_dev_fatal(dev, err, "completing transaction"); 1338 goto destroy_blkring; 1339 } 1340 1341 xenbus_switch_state(dev, XenbusStateInitialised); 1342 1343 return 0; 1344 1345 abort_transaction: 1346 xenbus_transaction_end(xbt, 1); 1347 if (message) 1348 xenbus_dev_fatal(dev, err, "%s", message); 1349 destroy_blkring: 1350 blkif_free(info, 0); 1351 out: 1352 return err; 1353 } 1354 1355 /** 1356 * Entry point to this code when a new device is created. Allocate the basic 1357 * structures and the ring buffer for communication with the backend, and 1358 * inform the backend of the appropriate details for those. Switch to 1359 * Initialised state. 1360 */ 1361 static int blkfront_probe(struct xenbus_device *dev, 1362 const struct xenbus_device_id *id) 1363 { 1364 int err, vdevice, i; 1365 struct blkfront_info *info; 1366 1367 /* FIXME: Use dynamic device id if this is not set. */ 1368 err = xenbus_scanf(XBT_NIL, dev->nodename, 1369 "virtual-device", "%i", &vdevice); 1370 if (err != 1) { 1371 /* go looking in the extended area instead */ 1372 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1373 "%i", &vdevice); 1374 if (err != 1) { 1375 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1376 return err; 1377 } 1378 } 1379 1380 if (xen_hvm_domain()) { 1381 char *type; 1382 int len; 1383 /* no unplug has been done: do not hook devices != xen vbds */ 1384 if (xen_has_pv_and_legacy_disk_devices()) { 1385 int major; 1386 1387 if (!VDEV_IS_EXTENDED(vdevice)) 1388 major = BLKIF_MAJOR(vdevice); 1389 else 1390 major = XENVBD_MAJOR; 1391 1392 if (major != XENVBD_MAJOR) { 1393 printk(KERN_INFO 1394 "%s: HVM does not support vbd %d as xen block device\n", 1395 __func__, vdevice); 1396 return -ENODEV; 1397 } 1398 } 1399 /* do not create a PV cdrom device if we are an HVM guest */ 1400 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1401 if (IS_ERR(type)) 1402 return -ENODEV; 1403 if (strncmp(type, "cdrom", 5) == 0) { 1404 kfree(type); 1405 return -ENODEV; 1406 } 1407 kfree(type); 1408 } 1409 info = kzalloc(sizeof(*info), GFP_KERNEL); 1410 if (!info) { 1411 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1412 return -ENOMEM; 1413 } 1414 1415 mutex_init(&info->mutex); 1416 spin_lock_init(&info->io_lock); 1417 info->xbdev = dev; 1418 info->vdevice = vdevice; 1419 INIT_LIST_HEAD(&info->grants); 1420 INIT_LIST_HEAD(&info->indirect_pages); 1421 info->persistent_gnts_c = 0; 1422 info->connected = BLKIF_STATE_DISCONNECTED; 1423 INIT_WORK(&info->work, blkif_restart_queue); 1424 1425 for (i = 0; i < BLK_RING_SIZE; i++) 1426 info->shadow[i].req.u.rw.id = i+1; 1427 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1428 1429 /* Front end dir is a number, which is used as the id. */ 1430 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1431 dev_set_drvdata(&dev->dev, info); 1432 1433 err = talk_to_blkback(dev, info); 1434 if (err) { 1435 kfree(info); 1436 dev_set_drvdata(&dev->dev, NULL); 1437 return err; 1438 } 1439 1440 return 0; 1441 } 1442 1443 static void split_bio_end(struct bio *bio, int error) 1444 { 1445 struct split_bio *split_bio = bio->bi_private; 1446 1447 if (error) 1448 split_bio->err = error; 1449 1450 if (atomic_dec_and_test(&split_bio->pending)) { 1451 split_bio->bio->bi_phys_segments = 0; 1452 bio_endio(split_bio->bio, split_bio->err); 1453 kfree(split_bio); 1454 } 1455 bio_put(bio); 1456 } 1457 1458 static int blkif_recover(struct blkfront_info *info) 1459 { 1460 int i; 1461 struct request *req, *n; 1462 struct blk_shadow *copy; 1463 int rc; 1464 struct bio *bio, *cloned_bio; 1465 struct bio_list bio_list, merge_bio; 1466 unsigned int segs, offset; 1467 int pending, size; 1468 struct split_bio *split_bio; 1469 struct list_head requests; 1470 1471 /* Stage 1: Make a safe copy of the shadow state. */ 1472 copy = kmemdup(info->shadow, sizeof(info->shadow), 1473 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); 1474 if (!copy) 1475 return -ENOMEM; 1476 1477 /* Stage 2: Set up free list. */ 1478 memset(&info->shadow, 0, sizeof(info->shadow)); 1479 for (i = 0; i < BLK_RING_SIZE; i++) 1480 info->shadow[i].req.u.rw.id = i+1; 1481 info->shadow_free = info->ring.req_prod_pvt; 1482 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1483 1484 rc = blkfront_setup_indirect(info); 1485 if (rc) { 1486 kfree(copy); 1487 return rc; 1488 } 1489 1490 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 1491 blk_queue_max_segments(info->rq, segs); 1492 bio_list_init(&bio_list); 1493 INIT_LIST_HEAD(&requests); 1494 for (i = 0; i < BLK_RING_SIZE; i++) { 1495 /* Not in use? */ 1496 if (!copy[i].request) 1497 continue; 1498 1499 /* 1500 * Get the bios in the request so we can re-queue them. 1501 */ 1502 if (copy[i].request->cmd_flags & 1503 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1504 /* 1505 * Flush operations don't contain bios, so 1506 * we need to requeue the whole request 1507 */ 1508 list_add(©[i].request->queuelist, &requests); 1509 continue; 1510 } 1511 merge_bio.head = copy[i].request->bio; 1512 merge_bio.tail = copy[i].request->biotail; 1513 bio_list_merge(&bio_list, &merge_bio); 1514 copy[i].request->bio = NULL; 1515 blk_end_request_all(copy[i].request, 0); 1516 } 1517 1518 kfree(copy); 1519 1520 /* 1521 * Empty the queue, this is important because we might have 1522 * requests in the queue with more segments than what we 1523 * can handle now. 1524 */ 1525 spin_lock_irq(&info->io_lock); 1526 while ((req = blk_fetch_request(info->rq)) != NULL) { 1527 if (req->cmd_flags & 1528 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1529 list_add(&req->queuelist, &requests); 1530 continue; 1531 } 1532 merge_bio.head = req->bio; 1533 merge_bio.tail = req->biotail; 1534 bio_list_merge(&bio_list, &merge_bio); 1535 req->bio = NULL; 1536 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) 1537 pr_alert("diskcache flush request found!\n"); 1538 __blk_end_request_all(req, 0); 1539 } 1540 spin_unlock_irq(&info->io_lock); 1541 1542 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1543 1544 spin_lock_irq(&info->io_lock); 1545 1546 /* Now safe for us to use the shared ring */ 1547 info->connected = BLKIF_STATE_CONNECTED; 1548 1549 /* Kick any other new requests queued since we resumed */ 1550 kick_pending_request_queues(info); 1551 1552 list_for_each_entry_safe(req, n, &requests, queuelist) { 1553 /* Requeue pending requests (flush or discard) */ 1554 list_del_init(&req->queuelist); 1555 BUG_ON(req->nr_phys_segments > segs); 1556 blk_requeue_request(info->rq, req); 1557 } 1558 spin_unlock_irq(&info->io_lock); 1559 1560 while ((bio = bio_list_pop(&bio_list)) != NULL) { 1561 /* Traverse the list of pending bios and re-queue them */ 1562 if (bio_segments(bio) > segs) { 1563 /* 1564 * This bio has more segments than what we can 1565 * handle, we have to split it. 1566 */ 1567 pending = (bio_segments(bio) + segs - 1) / segs; 1568 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO); 1569 BUG_ON(split_bio == NULL); 1570 atomic_set(&split_bio->pending, pending); 1571 split_bio->bio = bio; 1572 for (i = 0; i < pending; i++) { 1573 offset = (i * segs * PAGE_SIZE) >> 9; 1574 size = min((unsigned int)(segs * PAGE_SIZE) >> 9, 1575 (unsigned int)bio_sectors(bio) - offset); 1576 cloned_bio = bio_clone(bio, GFP_NOIO); 1577 BUG_ON(cloned_bio == NULL); 1578 bio_trim(cloned_bio, offset, size); 1579 cloned_bio->bi_private = split_bio; 1580 cloned_bio->bi_end_io = split_bio_end; 1581 submit_bio(cloned_bio->bi_rw, cloned_bio); 1582 } 1583 /* 1584 * Now we have to wait for all those smaller bios to 1585 * end, so we can also end the "parent" bio. 1586 */ 1587 continue; 1588 } 1589 /* We don't need to split this bio */ 1590 submit_bio(bio->bi_rw, bio); 1591 } 1592 1593 return 0; 1594 } 1595 1596 /** 1597 * We are reconnecting to the backend, due to a suspend/resume, or a backend 1598 * driver restart. We tear down our blkif structure and recreate it, but 1599 * leave the device-layer structures intact so that this is transparent to the 1600 * rest of the kernel. 1601 */ 1602 static int blkfront_resume(struct xenbus_device *dev) 1603 { 1604 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1605 int err; 1606 1607 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 1608 1609 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 1610 1611 err = talk_to_blkback(dev, info); 1612 1613 /* 1614 * We have to wait for the backend to switch to 1615 * connected state, since we want to read which 1616 * features it supports. 1617 */ 1618 1619 return err; 1620 } 1621 1622 static void 1623 blkfront_closing(struct blkfront_info *info) 1624 { 1625 struct xenbus_device *xbdev = info->xbdev; 1626 struct block_device *bdev = NULL; 1627 1628 mutex_lock(&info->mutex); 1629 1630 if (xbdev->state == XenbusStateClosing) { 1631 mutex_unlock(&info->mutex); 1632 return; 1633 } 1634 1635 if (info->gd) 1636 bdev = bdget_disk(info->gd, 0); 1637 1638 mutex_unlock(&info->mutex); 1639 1640 if (!bdev) { 1641 xenbus_frontend_closed(xbdev); 1642 return; 1643 } 1644 1645 mutex_lock(&bdev->bd_mutex); 1646 1647 if (bdev->bd_openers) { 1648 xenbus_dev_error(xbdev, -EBUSY, 1649 "Device in use; refusing to close"); 1650 xenbus_switch_state(xbdev, XenbusStateClosing); 1651 } else { 1652 xlvbd_release_gendisk(info); 1653 xenbus_frontend_closed(xbdev); 1654 } 1655 1656 mutex_unlock(&bdev->bd_mutex); 1657 bdput(bdev); 1658 } 1659 1660 static void blkfront_setup_discard(struct blkfront_info *info) 1661 { 1662 int err; 1663 unsigned int discard_granularity; 1664 unsigned int discard_alignment; 1665 unsigned int discard_secure; 1666 1667 info->feature_discard = 1; 1668 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1669 "discard-granularity", "%u", &discard_granularity, 1670 "discard-alignment", "%u", &discard_alignment, 1671 NULL); 1672 if (!err) { 1673 info->discard_granularity = discard_granularity; 1674 info->discard_alignment = discard_alignment; 1675 } 1676 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1677 "discard-secure", "%d", &discard_secure, 1678 NULL); 1679 if (!err) 1680 info->feature_secdiscard = !!discard_secure; 1681 } 1682 1683 static int blkfront_setup_indirect(struct blkfront_info *info) 1684 { 1685 unsigned int indirect_segments, segs; 1686 int err, i; 1687 1688 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1689 "feature-max-indirect-segments", "%u", &indirect_segments, 1690 NULL); 1691 if (err) { 1692 info->max_indirect_segments = 0; 1693 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST; 1694 } else { 1695 info->max_indirect_segments = min(indirect_segments, 1696 xen_blkif_max_segments); 1697 segs = info->max_indirect_segments; 1698 } 1699 1700 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE); 1701 if (err) 1702 goto out_of_memory; 1703 1704 if (!info->feature_persistent && info->max_indirect_segments) { 1705 /* 1706 * We are using indirect descriptors but not persistent 1707 * grants, we need to allocate a set of pages that can be 1708 * used for mapping indirect grefs 1709 */ 1710 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE; 1711 1712 BUG_ON(!list_empty(&info->indirect_pages)); 1713 for (i = 0; i < num; i++) { 1714 struct page *indirect_page = alloc_page(GFP_NOIO); 1715 if (!indirect_page) 1716 goto out_of_memory; 1717 list_add(&indirect_page->lru, &info->indirect_pages); 1718 } 1719 } 1720 1721 for (i = 0; i < BLK_RING_SIZE; i++) { 1722 info->shadow[i].grants_used = kzalloc( 1723 sizeof(info->shadow[i].grants_used[0]) * segs, 1724 GFP_NOIO); 1725 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO); 1726 if (info->max_indirect_segments) 1727 info->shadow[i].indirect_grants = kzalloc( 1728 sizeof(info->shadow[i].indirect_grants[0]) * 1729 INDIRECT_GREFS(segs), 1730 GFP_NOIO); 1731 if ((info->shadow[i].grants_used == NULL) || 1732 (info->shadow[i].sg == NULL) || 1733 (info->max_indirect_segments && 1734 (info->shadow[i].indirect_grants == NULL))) 1735 goto out_of_memory; 1736 sg_init_table(info->shadow[i].sg, segs); 1737 } 1738 1739 1740 return 0; 1741 1742 out_of_memory: 1743 for (i = 0; i < BLK_RING_SIZE; i++) { 1744 kfree(info->shadow[i].grants_used); 1745 info->shadow[i].grants_used = NULL; 1746 kfree(info->shadow[i].sg); 1747 info->shadow[i].sg = NULL; 1748 kfree(info->shadow[i].indirect_grants); 1749 info->shadow[i].indirect_grants = NULL; 1750 } 1751 if (!list_empty(&info->indirect_pages)) { 1752 struct page *indirect_page, *n; 1753 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 1754 list_del(&indirect_page->lru); 1755 __free_page(indirect_page); 1756 } 1757 } 1758 return -ENOMEM; 1759 } 1760 1761 /* 1762 * Invoked when the backend is finally 'ready' (and has told produced 1763 * the details about the physical device - #sectors, size, etc). 1764 */ 1765 static void blkfront_connect(struct blkfront_info *info) 1766 { 1767 unsigned long long sectors; 1768 unsigned long sector_size; 1769 unsigned int physical_sector_size; 1770 unsigned int binfo; 1771 int err; 1772 int barrier, flush, discard, persistent; 1773 1774 switch (info->connected) { 1775 case BLKIF_STATE_CONNECTED: 1776 /* 1777 * Potentially, the back-end may be signalling 1778 * a capacity change; update the capacity. 1779 */ 1780 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1781 "sectors", "%Lu", §ors); 1782 if (XENBUS_EXIST_ERR(err)) 1783 return; 1784 printk(KERN_INFO "Setting capacity to %Lu\n", 1785 sectors); 1786 set_capacity(info->gd, sectors); 1787 revalidate_disk(info->gd); 1788 1789 return; 1790 case BLKIF_STATE_SUSPENDED: 1791 /* 1792 * If we are recovering from suspension, we need to wait 1793 * for the backend to announce it's features before 1794 * reconnecting, at least we need to know if the backend 1795 * supports indirect descriptors, and how many. 1796 */ 1797 blkif_recover(info); 1798 return; 1799 1800 default: 1801 break; 1802 } 1803 1804 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 1805 __func__, info->xbdev->otherend); 1806 1807 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1808 "sectors", "%llu", §ors, 1809 "info", "%u", &binfo, 1810 "sector-size", "%lu", §or_size, 1811 NULL); 1812 if (err) { 1813 xenbus_dev_fatal(info->xbdev, err, 1814 "reading backend fields at %s", 1815 info->xbdev->otherend); 1816 return; 1817 } 1818 1819 /* 1820 * physcial-sector-size is a newer field, so old backends may not 1821 * provide this. Assume physical sector size to be the same as 1822 * sector_size in that case. 1823 */ 1824 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1825 "physical-sector-size", "%u", &physical_sector_size); 1826 if (err != 1) 1827 physical_sector_size = sector_size; 1828 1829 info->feature_flush = 0; 1830 1831 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1832 "feature-barrier", "%d", &barrier, 1833 NULL); 1834 1835 /* 1836 * If there's no "feature-barrier" defined, then it means 1837 * we're dealing with a very old backend which writes 1838 * synchronously; nothing to do. 1839 * 1840 * If there are barriers, then we use flush. 1841 */ 1842 if (!err && barrier) 1843 info->feature_flush = REQ_FLUSH | REQ_FUA; 1844 /* 1845 * And if there is "feature-flush-cache" use that above 1846 * barriers. 1847 */ 1848 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1849 "feature-flush-cache", "%d", &flush, 1850 NULL); 1851 1852 if (!err && flush) 1853 info->feature_flush = REQ_FLUSH; 1854 1855 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1856 "feature-discard", "%d", &discard, 1857 NULL); 1858 1859 if (!err && discard) 1860 blkfront_setup_discard(info); 1861 1862 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1863 "feature-persistent", "%u", &persistent, 1864 NULL); 1865 if (err) 1866 info->feature_persistent = 0; 1867 else 1868 info->feature_persistent = persistent; 1869 1870 err = blkfront_setup_indirect(info); 1871 if (err) { 1872 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 1873 info->xbdev->otherend); 1874 return; 1875 } 1876 1877 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 1878 physical_sector_size); 1879 if (err) { 1880 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 1881 info->xbdev->otherend); 1882 return; 1883 } 1884 1885 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1886 1887 /* Kick pending requests. */ 1888 spin_lock_irq(&info->io_lock); 1889 info->connected = BLKIF_STATE_CONNECTED; 1890 kick_pending_request_queues(info); 1891 spin_unlock_irq(&info->io_lock); 1892 1893 add_disk(info->gd); 1894 1895 info->is_ready = 1; 1896 } 1897 1898 /** 1899 * Callback received when the backend's state changes. 1900 */ 1901 static void blkback_changed(struct xenbus_device *dev, 1902 enum xenbus_state backend_state) 1903 { 1904 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1905 1906 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 1907 1908 switch (backend_state) { 1909 case XenbusStateInitialising: 1910 case XenbusStateInitWait: 1911 case XenbusStateInitialised: 1912 case XenbusStateReconfiguring: 1913 case XenbusStateReconfigured: 1914 case XenbusStateUnknown: 1915 break; 1916 1917 case XenbusStateConnected: 1918 blkfront_connect(info); 1919 break; 1920 1921 case XenbusStateClosed: 1922 if (dev->state == XenbusStateClosed) 1923 break; 1924 /* Missed the backend's Closing state -- fallthrough */ 1925 case XenbusStateClosing: 1926 blkfront_closing(info); 1927 break; 1928 } 1929 } 1930 1931 static int blkfront_remove(struct xenbus_device *xbdev) 1932 { 1933 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 1934 struct block_device *bdev = NULL; 1935 struct gendisk *disk; 1936 1937 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 1938 1939 blkif_free(info, 0); 1940 1941 mutex_lock(&info->mutex); 1942 1943 disk = info->gd; 1944 if (disk) 1945 bdev = bdget_disk(disk, 0); 1946 1947 info->xbdev = NULL; 1948 mutex_unlock(&info->mutex); 1949 1950 if (!bdev) { 1951 kfree(info); 1952 return 0; 1953 } 1954 1955 /* 1956 * The xbdev was removed before we reached the Closed 1957 * state. See if it's safe to remove the disk. If the bdev 1958 * isn't closed yet, we let release take care of it. 1959 */ 1960 1961 mutex_lock(&bdev->bd_mutex); 1962 info = disk->private_data; 1963 1964 dev_warn(disk_to_dev(disk), 1965 "%s was hot-unplugged, %d stale handles\n", 1966 xbdev->nodename, bdev->bd_openers); 1967 1968 if (info && !bdev->bd_openers) { 1969 xlvbd_release_gendisk(info); 1970 disk->private_data = NULL; 1971 kfree(info); 1972 } 1973 1974 mutex_unlock(&bdev->bd_mutex); 1975 bdput(bdev); 1976 1977 return 0; 1978 } 1979 1980 static int blkfront_is_ready(struct xenbus_device *dev) 1981 { 1982 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1983 1984 return info->is_ready && info->xbdev; 1985 } 1986 1987 static int blkif_open(struct block_device *bdev, fmode_t mode) 1988 { 1989 struct gendisk *disk = bdev->bd_disk; 1990 struct blkfront_info *info; 1991 int err = 0; 1992 1993 mutex_lock(&blkfront_mutex); 1994 1995 info = disk->private_data; 1996 if (!info) { 1997 /* xbdev gone */ 1998 err = -ERESTARTSYS; 1999 goto out; 2000 } 2001 2002 mutex_lock(&info->mutex); 2003 2004 if (!info->gd) 2005 /* xbdev is closed */ 2006 err = -ERESTARTSYS; 2007 2008 mutex_unlock(&info->mutex); 2009 2010 out: 2011 mutex_unlock(&blkfront_mutex); 2012 return err; 2013 } 2014 2015 static void blkif_release(struct gendisk *disk, fmode_t mode) 2016 { 2017 struct blkfront_info *info = disk->private_data; 2018 struct block_device *bdev; 2019 struct xenbus_device *xbdev; 2020 2021 mutex_lock(&blkfront_mutex); 2022 2023 bdev = bdget_disk(disk, 0); 2024 2025 if (!bdev) { 2026 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2027 goto out_mutex; 2028 } 2029 if (bdev->bd_openers) 2030 goto out; 2031 2032 /* 2033 * Check if we have been instructed to close. We will have 2034 * deferred this request, because the bdev was still open. 2035 */ 2036 2037 mutex_lock(&info->mutex); 2038 xbdev = info->xbdev; 2039 2040 if (xbdev && xbdev->state == XenbusStateClosing) { 2041 /* pending switch to state closed */ 2042 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2043 xlvbd_release_gendisk(info); 2044 xenbus_frontend_closed(info->xbdev); 2045 } 2046 2047 mutex_unlock(&info->mutex); 2048 2049 if (!xbdev) { 2050 /* sudden device removal */ 2051 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2052 xlvbd_release_gendisk(info); 2053 disk->private_data = NULL; 2054 kfree(info); 2055 } 2056 2057 out: 2058 bdput(bdev); 2059 out_mutex: 2060 mutex_unlock(&blkfront_mutex); 2061 } 2062 2063 static const struct block_device_operations xlvbd_block_fops = 2064 { 2065 .owner = THIS_MODULE, 2066 .open = blkif_open, 2067 .release = blkif_release, 2068 .getgeo = blkif_getgeo, 2069 .ioctl = blkif_ioctl, 2070 }; 2071 2072 2073 static const struct xenbus_device_id blkfront_ids[] = { 2074 { "vbd" }, 2075 { "" } 2076 }; 2077 2078 static struct xenbus_driver blkfront_driver = { 2079 .ids = blkfront_ids, 2080 .probe = blkfront_probe, 2081 .remove = blkfront_remove, 2082 .resume = blkfront_resume, 2083 .otherend_changed = blkback_changed, 2084 .is_ready = blkfront_is_ready, 2085 }; 2086 2087 static int __init xlblk_init(void) 2088 { 2089 int ret; 2090 2091 if (!xen_domain()) 2092 return -ENODEV; 2093 2094 if (!xen_has_pv_disk_devices()) 2095 return -ENODEV; 2096 2097 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2098 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2099 XENVBD_MAJOR, DEV_NAME); 2100 return -ENODEV; 2101 } 2102 2103 ret = xenbus_register_frontend(&blkfront_driver); 2104 if (ret) { 2105 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2106 return ret; 2107 } 2108 2109 return 0; 2110 } 2111 module_init(xlblk_init); 2112 2113 2114 static void __exit xlblk_exit(void) 2115 { 2116 xenbus_unregister_driver(&blkfront_driver); 2117 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2118 kfree(minors); 2119 } 2120 module_exit(xlblk_exit); 2121 2122 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2123 MODULE_LICENSE("GPL"); 2124 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2125 MODULE_ALIAS("xen:vbd"); 2126 MODULE_ALIAS("xenblk"); 2127