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 int err; 1249 1250 info->ring_ref = GRANT_INVALID_REF; 1251 1252 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH); 1253 if (!sring) { 1254 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1255 return -ENOMEM; 1256 } 1257 SHARED_RING_INIT(sring); 1258 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 1259 1260 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); 1261 if (err < 0) { 1262 free_page((unsigned long)sring); 1263 info->ring.sring = NULL; 1264 goto fail; 1265 } 1266 info->ring_ref = err; 1267 1268 err = xenbus_alloc_evtchn(dev, &info->evtchn); 1269 if (err) 1270 goto fail; 1271 1272 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0, 1273 "blkif", info); 1274 if (err <= 0) { 1275 xenbus_dev_fatal(dev, err, 1276 "bind_evtchn_to_irqhandler failed"); 1277 goto fail; 1278 } 1279 info->irq = err; 1280 1281 return 0; 1282 fail: 1283 blkif_free(info, 0); 1284 return err; 1285 } 1286 1287 1288 /* Common code used when first setting up, and when resuming. */ 1289 static int talk_to_blkback(struct xenbus_device *dev, 1290 struct blkfront_info *info) 1291 { 1292 const char *message = NULL; 1293 struct xenbus_transaction xbt; 1294 int err; 1295 1296 /* Create shared ring, alloc event channel. */ 1297 err = setup_blkring(dev, info); 1298 if (err) 1299 goto out; 1300 1301 again: 1302 err = xenbus_transaction_start(&xbt); 1303 if (err) { 1304 xenbus_dev_fatal(dev, err, "starting transaction"); 1305 goto destroy_blkring; 1306 } 1307 1308 err = xenbus_printf(xbt, dev->nodename, 1309 "ring-ref", "%u", info->ring_ref); 1310 if (err) { 1311 message = "writing ring-ref"; 1312 goto abort_transaction; 1313 } 1314 err = xenbus_printf(xbt, dev->nodename, 1315 "event-channel", "%u", info->evtchn); 1316 if (err) { 1317 message = "writing event-channel"; 1318 goto abort_transaction; 1319 } 1320 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1321 XEN_IO_PROTO_ABI_NATIVE); 1322 if (err) { 1323 message = "writing protocol"; 1324 goto abort_transaction; 1325 } 1326 err = xenbus_printf(xbt, dev->nodename, 1327 "feature-persistent", "%u", 1); 1328 if (err) 1329 dev_warn(&dev->dev, 1330 "writing persistent grants feature to xenbus"); 1331 1332 err = xenbus_transaction_end(xbt, 0); 1333 if (err) { 1334 if (err == -EAGAIN) 1335 goto again; 1336 xenbus_dev_fatal(dev, err, "completing transaction"); 1337 goto destroy_blkring; 1338 } 1339 1340 xenbus_switch_state(dev, XenbusStateInitialised); 1341 1342 return 0; 1343 1344 abort_transaction: 1345 xenbus_transaction_end(xbt, 1); 1346 if (message) 1347 xenbus_dev_fatal(dev, err, "%s", message); 1348 destroy_blkring: 1349 blkif_free(info, 0); 1350 out: 1351 return err; 1352 } 1353 1354 /** 1355 * Entry point to this code when a new device is created. Allocate the basic 1356 * structures and the ring buffer for communication with the backend, and 1357 * inform the backend of the appropriate details for those. Switch to 1358 * Initialised state. 1359 */ 1360 static int blkfront_probe(struct xenbus_device *dev, 1361 const struct xenbus_device_id *id) 1362 { 1363 int err, vdevice, i; 1364 struct blkfront_info *info; 1365 1366 /* FIXME: Use dynamic device id if this is not set. */ 1367 err = xenbus_scanf(XBT_NIL, dev->nodename, 1368 "virtual-device", "%i", &vdevice); 1369 if (err != 1) { 1370 /* go looking in the extended area instead */ 1371 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1372 "%i", &vdevice); 1373 if (err != 1) { 1374 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1375 return err; 1376 } 1377 } 1378 1379 if (xen_hvm_domain()) { 1380 char *type; 1381 int len; 1382 /* no unplug has been done: do not hook devices != xen vbds */ 1383 if (xen_has_pv_and_legacy_disk_devices()) { 1384 int major; 1385 1386 if (!VDEV_IS_EXTENDED(vdevice)) 1387 major = BLKIF_MAJOR(vdevice); 1388 else 1389 major = XENVBD_MAJOR; 1390 1391 if (major != XENVBD_MAJOR) { 1392 printk(KERN_INFO 1393 "%s: HVM does not support vbd %d as xen block device\n", 1394 __FUNCTION__, vdevice); 1395 return -ENODEV; 1396 } 1397 } 1398 /* do not create a PV cdrom device if we are an HVM guest */ 1399 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1400 if (IS_ERR(type)) 1401 return -ENODEV; 1402 if (strncmp(type, "cdrom", 5) == 0) { 1403 kfree(type); 1404 return -ENODEV; 1405 } 1406 kfree(type); 1407 } 1408 info = kzalloc(sizeof(*info), GFP_KERNEL); 1409 if (!info) { 1410 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1411 return -ENOMEM; 1412 } 1413 1414 mutex_init(&info->mutex); 1415 spin_lock_init(&info->io_lock); 1416 info->xbdev = dev; 1417 info->vdevice = vdevice; 1418 INIT_LIST_HEAD(&info->grants); 1419 INIT_LIST_HEAD(&info->indirect_pages); 1420 info->persistent_gnts_c = 0; 1421 info->connected = BLKIF_STATE_DISCONNECTED; 1422 INIT_WORK(&info->work, blkif_restart_queue); 1423 1424 for (i = 0; i < BLK_RING_SIZE; i++) 1425 info->shadow[i].req.u.rw.id = i+1; 1426 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1427 1428 /* Front end dir is a number, which is used as the id. */ 1429 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1430 dev_set_drvdata(&dev->dev, info); 1431 1432 err = talk_to_blkback(dev, info); 1433 if (err) { 1434 kfree(info); 1435 dev_set_drvdata(&dev->dev, NULL); 1436 return err; 1437 } 1438 1439 return 0; 1440 } 1441 1442 static void split_bio_end(struct bio *bio, int error) 1443 { 1444 struct split_bio *split_bio = bio->bi_private; 1445 1446 if (error) 1447 split_bio->err = error; 1448 1449 if (atomic_dec_and_test(&split_bio->pending)) { 1450 split_bio->bio->bi_phys_segments = 0; 1451 bio_endio(split_bio->bio, split_bio->err); 1452 kfree(split_bio); 1453 } 1454 bio_put(bio); 1455 } 1456 1457 static int blkif_recover(struct blkfront_info *info) 1458 { 1459 int i; 1460 struct request *req, *n; 1461 struct blk_shadow *copy; 1462 int rc; 1463 struct bio *bio, *cloned_bio; 1464 struct bio_list bio_list, merge_bio; 1465 unsigned int segs, offset; 1466 int pending, size; 1467 struct split_bio *split_bio; 1468 struct list_head requests; 1469 1470 /* Stage 1: Make a safe copy of the shadow state. */ 1471 copy = kmemdup(info->shadow, sizeof(info->shadow), 1472 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); 1473 if (!copy) 1474 return -ENOMEM; 1475 1476 /* Stage 2: Set up free list. */ 1477 memset(&info->shadow, 0, sizeof(info->shadow)); 1478 for (i = 0; i < BLK_RING_SIZE; i++) 1479 info->shadow[i].req.u.rw.id = i+1; 1480 info->shadow_free = info->ring.req_prod_pvt; 1481 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1482 1483 rc = blkfront_setup_indirect(info); 1484 if (rc) { 1485 kfree(copy); 1486 return rc; 1487 } 1488 1489 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 1490 blk_queue_max_segments(info->rq, segs); 1491 bio_list_init(&bio_list); 1492 INIT_LIST_HEAD(&requests); 1493 for (i = 0; i < BLK_RING_SIZE; i++) { 1494 /* Not in use? */ 1495 if (!copy[i].request) 1496 continue; 1497 1498 /* 1499 * Get the bios in the request so we can re-queue them. 1500 */ 1501 if (copy[i].request->cmd_flags & 1502 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1503 /* 1504 * Flush operations don't contain bios, so 1505 * we need to requeue the whole request 1506 */ 1507 list_add(©[i].request->queuelist, &requests); 1508 continue; 1509 } 1510 merge_bio.head = copy[i].request->bio; 1511 merge_bio.tail = copy[i].request->biotail; 1512 bio_list_merge(&bio_list, &merge_bio); 1513 copy[i].request->bio = NULL; 1514 blk_put_request(copy[i].request); 1515 } 1516 1517 kfree(copy); 1518 1519 /* 1520 * Empty the queue, this is important because we might have 1521 * requests in the queue with more segments than what we 1522 * can handle now. 1523 */ 1524 spin_lock_irq(&info->io_lock); 1525 while ((req = blk_fetch_request(info->rq)) != NULL) { 1526 if (req->cmd_flags & 1527 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1528 list_add(&req->queuelist, &requests); 1529 continue; 1530 } 1531 merge_bio.head = req->bio; 1532 merge_bio.tail = req->biotail; 1533 bio_list_merge(&bio_list, &merge_bio); 1534 req->bio = NULL; 1535 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) 1536 pr_alert("diskcache flush request found!\n"); 1537 __blk_put_request(info->rq, req); 1538 } 1539 spin_unlock_irq(&info->io_lock); 1540 1541 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1542 1543 spin_lock_irq(&info->io_lock); 1544 1545 /* Now safe for us to use the shared ring */ 1546 info->connected = BLKIF_STATE_CONNECTED; 1547 1548 /* Kick any other new requests queued since we resumed */ 1549 kick_pending_request_queues(info); 1550 1551 list_for_each_entry_safe(req, n, &requests, queuelist) { 1552 /* Requeue pending requests (flush or discard) */ 1553 list_del_init(&req->queuelist); 1554 BUG_ON(req->nr_phys_segments > segs); 1555 blk_requeue_request(info->rq, req); 1556 } 1557 spin_unlock_irq(&info->io_lock); 1558 1559 while ((bio = bio_list_pop(&bio_list)) != NULL) { 1560 /* Traverse the list of pending bios and re-queue them */ 1561 if (bio_segments(bio) > segs) { 1562 /* 1563 * This bio has more segments than what we can 1564 * handle, we have to split it. 1565 */ 1566 pending = (bio_segments(bio) + segs - 1) / segs; 1567 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO); 1568 BUG_ON(split_bio == NULL); 1569 atomic_set(&split_bio->pending, pending); 1570 split_bio->bio = bio; 1571 for (i = 0; i < pending; i++) { 1572 offset = (i * segs * PAGE_SIZE) >> 9; 1573 size = min((unsigned int)(segs * PAGE_SIZE) >> 9, 1574 (unsigned int)bio_sectors(bio) - offset); 1575 cloned_bio = bio_clone(bio, GFP_NOIO); 1576 BUG_ON(cloned_bio == NULL); 1577 bio_trim(cloned_bio, offset, size); 1578 cloned_bio->bi_private = split_bio; 1579 cloned_bio->bi_end_io = split_bio_end; 1580 submit_bio(cloned_bio->bi_rw, cloned_bio); 1581 } 1582 /* 1583 * Now we have to wait for all those smaller bios to 1584 * end, so we can also end the "parent" bio. 1585 */ 1586 continue; 1587 } 1588 /* We don't need to split this bio */ 1589 submit_bio(bio->bi_rw, bio); 1590 } 1591 1592 return 0; 1593 } 1594 1595 /** 1596 * We are reconnecting to the backend, due to a suspend/resume, or a backend 1597 * driver restart. We tear down our blkif structure and recreate it, but 1598 * leave the device-layer structures intact so that this is transparent to the 1599 * rest of the kernel. 1600 */ 1601 static int blkfront_resume(struct xenbus_device *dev) 1602 { 1603 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1604 int err; 1605 1606 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 1607 1608 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 1609 1610 err = talk_to_blkback(dev, info); 1611 1612 /* 1613 * We have to wait for the backend to switch to 1614 * connected state, since we want to read which 1615 * features it supports. 1616 */ 1617 1618 return err; 1619 } 1620 1621 static void 1622 blkfront_closing(struct blkfront_info *info) 1623 { 1624 struct xenbus_device *xbdev = info->xbdev; 1625 struct block_device *bdev = NULL; 1626 1627 mutex_lock(&info->mutex); 1628 1629 if (xbdev->state == XenbusStateClosing) { 1630 mutex_unlock(&info->mutex); 1631 return; 1632 } 1633 1634 if (info->gd) 1635 bdev = bdget_disk(info->gd, 0); 1636 1637 mutex_unlock(&info->mutex); 1638 1639 if (!bdev) { 1640 xenbus_frontend_closed(xbdev); 1641 return; 1642 } 1643 1644 mutex_lock(&bdev->bd_mutex); 1645 1646 if (bdev->bd_openers) { 1647 xenbus_dev_error(xbdev, -EBUSY, 1648 "Device in use; refusing to close"); 1649 xenbus_switch_state(xbdev, XenbusStateClosing); 1650 } else { 1651 xlvbd_release_gendisk(info); 1652 xenbus_frontend_closed(xbdev); 1653 } 1654 1655 mutex_unlock(&bdev->bd_mutex); 1656 bdput(bdev); 1657 } 1658 1659 static void blkfront_setup_discard(struct blkfront_info *info) 1660 { 1661 int err; 1662 unsigned int discard_granularity; 1663 unsigned int discard_alignment; 1664 unsigned int discard_secure; 1665 1666 info->feature_discard = 1; 1667 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1668 "discard-granularity", "%u", &discard_granularity, 1669 "discard-alignment", "%u", &discard_alignment, 1670 NULL); 1671 if (!err) { 1672 info->discard_granularity = discard_granularity; 1673 info->discard_alignment = discard_alignment; 1674 } 1675 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1676 "discard-secure", "%d", &discard_secure, 1677 NULL); 1678 if (!err) 1679 info->feature_secdiscard = !!discard_secure; 1680 } 1681 1682 static int blkfront_setup_indirect(struct blkfront_info *info) 1683 { 1684 unsigned int indirect_segments, segs; 1685 int err, i; 1686 1687 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1688 "feature-max-indirect-segments", "%u", &indirect_segments, 1689 NULL); 1690 if (err) { 1691 info->max_indirect_segments = 0; 1692 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST; 1693 } else { 1694 info->max_indirect_segments = min(indirect_segments, 1695 xen_blkif_max_segments); 1696 segs = info->max_indirect_segments; 1697 } 1698 1699 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE); 1700 if (err) 1701 goto out_of_memory; 1702 1703 if (!info->feature_persistent && info->max_indirect_segments) { 1704 /* 1705 * We are using indirect descriptors but not persistent 1706 * grants, we need to allocate a set of pages that can be 1707 * used for mapping indirect grefs 1708 */ 1709 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE; 1710 1711 BUG_ON(!list_empty(&info->indirect_pages)); 1712 for (i = 0; i < num; i++) { 1713 struct page *indirect_page = alloc_page(GFP_NOIO); 1714 if (!indirect_page) 1715 goto out_of_memory; 1716 list_add(&indirect_page->lru, &info->indirect_pages); 1717 } 1718 } 1719 1720 for (i = 0; i < BLK_RING_SIZE; i++) { 1721 info->shadow[i].grants_used = kzalloc( 1722 sizeof(info->shadow[i].grants_used[0]) * segs, 1723 GFP_NOIO); 1724 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO); 1725 if (info->max_indirect_segments) 1726 info->shadow[i].indirect_grants = kzalloc( 1727 sizeof(info->shadow[i].indirect_grants[0]) * 1728 INDIRECT_GREFS(segs), 1729 GFP_NOIO); 1730 if ((info->shadow[i].grants_used == NULL) || 1731 (info->shadow[i].sg == NULL) || 1732 (info->max_indirect_segments && 1733 (info->shadow[i].indirect_grants == NULL))) 1734 goto out_of_memory; 1735 sg_init_table(info->shadow[i].sg, segs); 1736 } 1737 1738 1739 return 0; 1740 1741 out_of_memory: 1742 for (i = 0; i < BLK_RING_SIZE; i++) { 1743 kfree(info->shadow[i].grants_used); 1744 info->shadow[i].grants_used = NULL; 1745 kfree(info->shadow[i].sg); 1746 info->shadow[i].sg = NULL; 1747 kfree(info->shadow[i].indirect_grants); 1748 info->shadow[i].indirect_grants = NULL; 1749 } 1750 if (!list_empty(&info->indirect_pages)) { 1751 struct page *indirect_page, *n; 1752 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 1753 list_del(&indirect_page->lru); 1754 __free_page(indirect_page); 1755 } 1756 } 1757 return -ENOMEM; 1758 } 1759 1760 /* 1761 * Invoked when the backend is finally 'ready' (and has told produced 1762 * the details about the physical device - #sectors, size, etc). 1763 */ 1764 static void blkfront_connect(struct blkfront_info *info) 1765 { 1766 unsigned long long sectors; 1767 unsigned long sector_size; 1768 unsigned int physical_sector_size; 1769 unsigned int binfo; 1770 int err; 1771 int barrier, flush, discard, persistent; 1772 1773 switch (info->connected) { 1774 case BLKIF_STATE_CONNECTED: 1775 /* 1776 * Potentially, the back-end may be signalling 1777 * a capacity change; update the capacity. 1778 */ 1779 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1780 "sectors", "%Lu", §ors); 1781 if (XENBUS_EXIST_ERR(err)) 1782 return; 1783 printk(KERN_INFO "Setting capacity to %Lu\n", 1784 sectors); 1785 set_capacity(info->gd, sectors); 1786 revalidate_disk(info->gd); 1787 1788 return; 1789 case BLKIF_STATE_SUSPENDED: 1790 /* 1791 * If we are recovering from suspension, we need to wait 1792 * for the backend to announce it's features before 1793 * reconnecting, at least we need to know if the backend 1794 * supports indirect descriptors, and how many. 1795 */ 1796 blkif_recover(info); 1797 return; 1798 1799 default: 1800 break; 1801 } 1802 1803 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 1804 __func__, info->xbdev->otherend); 1805 1806 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1807 "sectors", "%llu", §ors, 1808 "info", "%u", &binfo, 1809 "sector-size", "%lu", §or_size, 1810 NULL); 1811 if (err) { 1812 xenbus_dev_fatal(info->xbdev, err, 1813 "reading backend fields at %s", 1814 info->xbdev->otherend); 1815 return; 1816 } 1817 1818 /* 1819 * physcial-sector-size is a newer field, so old backends may not 1820 * provide this. Assume physical sector size to be the same as 1821 * sector_size in that case. 1822 */ 1823 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1824 "physical-sector-size", "%u", &physical_sector_size); 1825 if (err != 1) 1826 physical_sector_size = sector_size; 1827 1828 info->feature_flush = 0; 1829 1830 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1831 "feature-barrier", "%d", &barrier, 1832 NULL); 1833 1834 /* 1835 * If there's no "feature-barrier" defined, then it means 1836 * we're dealing with a very old backend which writes 1837 * synchronously; nothing to do. 1838 * 1839 * If there are barriers, then we use flush. 1840 */ 1841 if (!err && barrier) 1842 info->feature_flush = REQ_FLUSH | REQ_FUA; 1843 /* 1844 * And if there is "feature-flush-cache" use that above 1845 * barriers. 1846 */ 1847 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1848 "feature-flush-cache", "%d", &flush, 1849 NULL); 1850 1851 if (!err && flush) 1852 info->feature_flush = REQ_FLUSH; 1853 1854 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1855 "feature-discard", "%d", &discard, 1856 NULL); 1857 1858 if (!err && discard) 1859 blkfront_setup_discard(info); 1860 1861 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1862 "feature-persistent", "%u", &persistent, 1863 NULL); 1864 if (err) 1865 info->feature_persistent = 0; 1866 else 1867 info->feature_persistent = persistent; 1868 1869 err = blkfront_setup_indirect(info); 1870 if (err) { 1871 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 1872 info->xbdev->otherend); 1873 return; 1874 } 1875 1876 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 1877 physical_sector_size); 1878 if (err) { 1879 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 1880 info->xbdev->otherend); 1881 return; 1882 } 1883 1884 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1885 1886 /* Kick pending requests. */ 1887 spin_lock_irq(&info->io_lock); 1888 info->connected = BLKIF_STATE_CONNECTED; 1889 kick_pending_request_queues(info); 1890 spin_unlock_irq(&info->io_lock); 1891 1892 add_disk(info->gd); 1893 1894 info->is_ready = 1; 1895 } 1896 1897 /** 1898 * Callback received when the backend's state changes. 1899 */ 1900 static void blkback_changed(struct xenbus_device *dev, 1901 enum xenbus_state backend_state) 1902 { 1903 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1904 1905 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 1906 1907 switch (backend_state) { 1908 case XenbusStateInitialising: 1909 case XenbusStateInitWait: 1910 case XenbusStateInitialised: 1911 case XenbusStateReconfiguring: 1912 case XenbusStateReconfigured: 1913 case XenbusStateUnknown: 1914 break; 1915 1916 case XenbusStateConnected: 1917 blkfront_connect(info); 1918 break; 1919 1920 case XenbusStateClosed: 1921 if (dev->state == XenbusStateClosed) 1922 break; 1923 /* Missed the backend's Closing state -- fallthrough */ 1924 case XenbusStateClosing: 1925 blkfront_closing(info); 1926 break; 1927 } 1928 } 1929 1930 static int blkfront_remove(struct xenbus_device *xbdev) 1931 { 1932 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 1933 struct block_device *bdev = NULL; 1934 struct gendisk *disk; 1935 1936 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 1937 1938 blkif_free(info, 0); 1939 1940 mutex_lock(&info->mutex); 1941 1942 disk = info->gd; 1943 if (disk) 1944 bdev = bdget_disk(disk, 0); 1945 1946 info->xbdev = NULL; 1947 mutex_unlock(&info->mutex); 1948 1949 if (!bdev) { 1950 kfree(info); 1951 return 0; 1952 } 1953 1954 /* 1955 * The xbdev was removed before we reached the Closed 1956 * state. See if it's safe to remove the disk. If the bdev 1957 * isn't closed yet, we let release take care of it. 1958 */ 1959 1960 mutex_lock(&bdev->bd_mutex); 1961 info = disk->private_data; 1962 1963 dev_warn(disk_to_dev(disk), 1964 "%s was hot-unplugged, %d stale handles\n", 1965 xbdev->nodename, bdev->bd_openers); 1966 1967 if (info && !bdev->bd_openers) { 1968 xlvbd_release_gendisk(info); 1969 disk->private_data = NULL; 1970 kfree(info); 1971 } 1972 1973 mutex_unlock(&bdev->bd_mutex); 1974 bdput(bdev); 1975 1976 return 0; 1977 } 1978 1979 static int blkfront_is_ready(struct xenbus_device *dev) 1980 { 1981 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1982 1983 return info->is_ready && info->xbdev; 1984 } 1985 1986 static int blkif_open(struct block_device *bdev, fmode_t mode) 1987 { 1988 struct gendisk *disk = bdev->bd_disk; 1989 struct blkfront_info *info; 1990 int err = 0; 1991 1992 mutex_lock(&blkfront_mutex); 1993 1994 info = disk->private_data; 1995 if (!info) { 1996 /* xbdev gone */ 1997 err = -ERESTARTSYS; 1998 goto out; 1999 } 2000 2001 mutex_lock(&info->mutex); 2002 2003 if (!info->gd) 2004 /* xbdev is closed */ 2005 err = -ERESTARTSYS; 2006 2007 mutex_unlock(&info->mutex); 2008 2009 out: 2010 mutex_unlock(&blkfront_mutex); 2011 return err; 2012 } 2013 2014 static void blkif_release(struct gendisk *disk, fmode_t mode) 2015 { 2016 struct blkfront_info *info = disk->private_data; 2017 struct block_device *bdev; 2018 struct xenbus_device *xbdev; 2019 2020 mutex_lock(&blkfront_mutex); 2021 2022 bdev = bdget_disk(disk, 0); 2023 2024 if (!bdev) { 2025 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2026 goto out_mutex; 2027 } 2028 if (bdev->bd_openers) 2029 goto out; 2030 2031 /* 2032 * Check if we have been instructed to close. We will have 2033 * deferred this request, because the bdev was still open. 2034 */ 2035 2036 mutex_lock(&info->mutex); 2037 xbdev = info->xbdev; 2038 2039 if (xbdev && xbdev->state == XenbusStateClosing) { 2040 /* pending switch to state closed */ 2041 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2042 xlvbd_release_gendisk(info); 2043 xenbus_frontend_closed(info->xbdev); 2044 } 2045 2046 mutex_unlock(&info->mutex); 2047 2048 if (!xbdev) { 2049 /* sudden device removal */ 2050 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2051 xlvbd_release_gendisk(info); 2052 disk->private_data = NULL; 2053 kfree(info); 2054 } 2055 2056 out: 2057 bdput(bdev); 2058 out_mutex: 2059 mutex_unlock(&blkfront_mutex); 2060 } 2061 2062 static const struct block_device_operations xlvbd_block_fops = 2063 { 2064 .owner = THIS_MODULE, 2065 .open = blkif_open, 2066 .release = blkif_release, 2067 .getgeo = blkif_getgeo, 2068 .ioctl = blkif_ioctl, 2069 }; 2070 2071 2072 static const struct xenbus_device_id blkfront_ids[] = { 2073 { "vbd" }, 2074 { "" } 2075 }; 2076 2077 static struct xenbus_driver blkfront_driver = { 2078 .ids = blkfront_ids, 2079 .probe = blkfront_probe, 2080 .remove = blkfront_remove, 2081 .resume = blkfront_resume, 2082 .otherend_changed = blkback_changed, 2083 .is_ready = blkfront_is_ready, 2084 }; 2085 2086 static int __init xlblk_init(void) 2087 { 2088 int ret; 2089 2090 if (!xen_domain()) 2091 return -ENODEV; 2092 2093 if (!xen_has_pv_disk_devices()) 2094 return -ENODEV; 2095 2096 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2097 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2098 XENVBD_MAJOR, DEV_NAME); 2099 return -ENODEV; 2100 } 2101 2102 ret = xenbus_register_frontend(&blkfront_driver); 2103 if (ret) { 2104 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2105 return ret; 2106 } 2107 2108 return 0; 2109 } 2110 module_init(xlblk_init); 2111 2112 2113 static void __exit xlblk_exit(void) 2114 { 2115 xenbus_unregister_driver(&blkfront_driver); 2116 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2117 kfree(minors); 2118 } 2119 module_exit(xlblk_exit); 2120 2121 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2122 MODULE_LICENSE("GPL"); 2123 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2124 MODULE_ALIAS("xen:vbd"); 2125 MODULE_ALIAS("xenblk"); 2126