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/blk-mq.h> 41 #include <linux/hdreg.h> 42 #include <linux/cdrom.h> 43 #include <linux/module.h> 44 #include <linux/slab.h> 45 #include <linux/mutex.h> 46 #include <linux/scatterlist.h> 47 #include <linux/bitmap.h> 48 #include <linux/list.h> 49 50 #include <xen/xen.h> 51 #include <xen/xenbus.h> 52 #include <xen/grant_table.h> 53 #include <xen/events.h> 54 #include <xen/page.h> 55 #include <xen/platform_pci.h> 56 57 #include <xen/interface/grant_table.h> 58 #include <xen/interface/io/blkif.h> 59 #include <xen/interface/io/protocols.h> 60 61 #include <asm/xen/hypervisor.h> 62 63 enum blkif_state { 64 BLKIF_STATE_DISCONNECTED, 65 BLKIF_STATE_CONNECTED, 66 BLKIF_STATE_SUSPENDED, 67 }; 68 69 struct grant { 70 grant_ref_t gref; 71 unsigned long pfn; 72 struct list_head node; 73 }; 74 75 struct blk_shadow { 76 struct blkif_request req; 77 struct request *request; 78 struct grant **grants_used; 79 struct grant **indirect_grants; 80 struct scatterlist *sg; 81 }; 82 83 struct split_bio { 84 struct bio *bio; 85 atomic_t pending; 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 /* 102 * Maximum order of pages to be used for the shared ring between front and 103 * backend, 4KB page granularity is used. 104 */ 105 static unsigned int xen_blkif_max_ring_order; 106 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO); 107 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 108 109 #define BLK_RING_SIZE(info) __CONST_RING_SIZE(blkif, PAGE_SIZE * (info)->nr_ring_pages) 110 #define BLK_MAX_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE * XENBUS_MAX_RING_PAGES) 111 /* 112 * ring-ref%i i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 113 * characters are enough. Define to 20 to keep consist with backend. 114 */ 115 #define RINGREF_NAME_LEN (20) 116 117 /* 118 * We have one of these per vbd, whether ide, scsi or 'other'. They 119 * hang in private_data off the gendisk structure. We may end up 120 * putting all kinds of interesting stuff here :-) 121 */ 122 struct blkfront_info 123 { 124 spinlock_t io_lock; 125 struct mutex mutex; 126 struct xenbus_device *xbdev; 127 struct gendisk *gd; 128 int vdevice; 129 blkif_vdev_t handle; 130 enum blkif_state connected; 131 int ring_ref[XENBUS_MAX_RING_PAGES]; 132 unsigned int nr_ring_pages; 133 struct blkif_front_ring ring; 134 unsigned int evtchn, irq; 135 struct request_queue *rq; 136 struct work_struct work; 137 struct gnttab_free_callback callback; 138 struct blk_shadow shadow[BLK_MAX_RING_SIZE]; 139 struct list_head grants; 140 struct list_head indirect_pages; 141 unsigned int persistent_gnts_c; 142 unsigned long shadow_free; 143 unsigned int feature_flush; 144 unsigned int feature_discard:1; 145 unsigned int feature_secdiscard:1; 146 unsigned int discard_granularity; 147 unsigned int discard_alignment; 148 unsigned int feature_persistent:1; 149 unsigned int max_indirect_segments; 150 int is_ready; 151 struct blk_mq_tag_set tag_set; 152 }; 153 154 static unsigned int nr_minors; 155 static unsigned long *minors; 156 static DEFINE_SPINLOCK(minor_lock); 157 158 #define GRANT_INVALID_REF 0 159 160 #define PARTS_PER_DISK 16 161 #define PARTS_PER_EXT_DISK 256 162 163 #define BLKIF_MAJOR(dev) ((dev)>>8) 164 #define BLKIF_MINOR(dev) ((dev) & 0xff) 165 166 #define EXT_SHIFT 28 167 #define EXTENDED (1<<EXT_SHIFT) 168 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 169 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 170 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 171 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 172 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 173 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 174 175 #define DEV_NAME "xvd" /* name in /dev */ 176 177 #define SEGS_PER_INDIRECT_FRAME \ 178 (PAGE_SIZE/sizeof(struct blkif_request_segment)) 179 #define INDIRECT_GREFS(_segs) \ 180 ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME) 181 182 static int blkfront_setup_indirect(struct blkfront_info *info); 183 static int blkfront_gather_backend_features(struct blkfront_info *info); 184 185 static int get_id_from_freelist(struct blkfront_info *info) 186 { 187 unsigned long free = info->shadow_free; 188 BUG_ON(free >= BLK_RING_SIZE(info)); 189 info->shadow_free = info->shadow[free].req.u.rw.id; 190 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 191 return free; 192 } 193 194 static int add_id_to_freelist(struct blkfront_info *info, 195 unsigned long id) 196 { 197 if (info->shadow[id].req.u.rw.id != id) 198 return -EINVAL; 199 if (info->shadow[id].request == NULL) 200 return -EINVAL; 201 info->shadow[id].req.u.rw.id = info->shadow_free; 202 info->shadow[id].request = NULL; 203 info->shadow_free = id; 204 return 0; 205 } 206 207 static int fill_grant_buffer(struct blkfront_info *info, int num) 208 { 209 struct page *granted_page; 210 struct grant *gnt_list_entry, *n; 211 int i = 0; 212 213 while(i < num) { 214 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 215 if (!gnt_list_entry) 216 goto out_of_memory; 217 218 if (info->feature_persistent) { 219 granted_page = alloc_page(GFP_NOIO); 220 if (!granted_page) { 221 kfree(gnt_list_entry); 222 goto out_of_memory; 223 } 224 gnt_list_entry->pfn = page_to_pfn(granted_page); 225 } 226 227 gnt_list_entry->gref = GRANT_INVALID_REF; 228 list_add(&gnt_list_entry->node, &info->grants); 229 i++; 230 } 231 232 return 0; 233 234 out_of_memory: 235 list_for_each_entry_safe(gnt_list_entry, n, 236 &info->grants, node) { 237 list_del(&gnt_list_entry->node); 238 if (info->feature_persistent) 239 __free_page(pfn_to_page(gnt_list_entry->pfn)); 240 kfree(gnt_list_entry); 241 i--; 242 } 243 BUG_ON(i != 0); 244 return -ENOMEM; 245 } 246 247 static struct grant *get_grant(grant_ref_t *gref_head, 248 unsigned long pfn, 249 struct blkfront_info *info) 250 { 251 struct grant *gnt_list_entry; 252 unsigned long buffer_gfn; 253 254 BUG_ON(list_empty(&info->grants)); 255 gnt_list_entry = list_first_entry(&info->grants, struct grant, 256 node); 257 list_del(&gnt_list_entry->node); 258 259 if (gnt_list_entry->gref != GRANT_INVALID_REF) { 260 info->persistent_gnts_c--; 261 return gnt_list_entry; 262 } 263 264 /* Assign a gref to this page */ 265 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 266 BUG_ON(gnt_list_entry->gref == -ENOSPC); 267 if (!info->feature_persistent) { 268 BUG_ON(!pfn); 269 gnt_list_entry->pfn = pfn; 270 } 271 buffer_gfn = pfn_to_gfn(gnt_list_entry->pfn); 272 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 273 info->xbdev->otherend_id, 274 buffer_gfn, 0); 275 return gnt_list_entry; 276 } 277 278 static const char *op_name(int op) 279 { 280 static const char *const names[] = { 281 [BLKIF_OP_READ] = "read", 282 [BLKIF_OP_WRITE] = "write", 283 [BLKIF_OP_WRITE_BARRIER] = "barrier", 284 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 285 [BLKIF_OP_DISCARD] = "discard" }; 286 287 if (op < 0 || op >= ARRAY_SIZE(names)) 288 return "unknown"; 289 290 if (!names[op]) 291 return "reserved"; 292 293 return names[op]; 294 } 295 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 296 { 297 unsigned int end = minor + nr; 298 int rc; 299 300 if (end > nr_minors) { 301 unsigned long *bitmap, *old; 302 303 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 304 GFP_KERNEL); 305 if (bitmap == NULL) 306 return -ENOMEM; 307 308 spin_lock(&minor_lock); 309 if (end > nr_minors) { 310 old = minors; 311 memcpy(bitmap, minors, 312 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 313 minors = bitmap; 314 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 315 } else 316 old = bitmap; 317 spin_unlock(&minor_lock); 318 kfree(old); 319 } 320 321 spin_lock(&minor_lock); 322 if (find_next_bit(minors, end, minor) >= end) { 323 bitmap_set(minors, minor, nr); 324 rc = 0; 325 } else 326 rc = -EBUSY; 327 spin_unlock(&minor_lock); 328 329 return rc; 330 } 331 332 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 333 { 334 unsigned int end = minor + nr; 335 336 BUG_ON(end > nr_minors); 337 spin_lock(&minor_lock); 338 bitmap_clear(minors, minor, nr); 339 spin_unlock(&minor_lock); 340 } 341 342 static void blkif_restart_queue_callback(void *arg) 343 { 344 struct blkfront_info *info = (struct blkfront_info *)arg; 345 schedule_work(&info->work); 346 } 347 348 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 349 { 350 /* We don't have real geometry info, but let's at least return 351 values consistent with the size of the device */ 352 sector_t nsect = get_capacity(bd->bd_disk); 353 sector_t cylinders = nsect; 354 355 hg->heads = 0xff; 356 hg->sectors = 0x3f; 357 sector_div(cylinders, hg->heads * hg->sectors); 358 hg->cylinders = cylinders; 359 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 360 hg->cylinders = 0xffff; 361 return 0; 362 } 363 364 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 365 unsigned command, unsigned long argument) 366 { 367 struct blkfront_info *info = bdev->bd_disk->private_data; 368 int i; 369 370 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 371 command, (long)argument); 372 373 switch (command) { 374 case CDROMMULTISESSION: 375 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 376 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 377 if (put_user(0, (char __user *)(argument + i))) 378 return -EFAULT; 379 return 0; 380 381 case CDROM_GET_CAPABILITY: { 382 struct gendisk *gd = info->gd; 383 if (gd->flags & GENHD_FL_CD) 384 return 0; 385 return -EINVAL; 386 } 387 388 default: 389 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 390 command);*/ 391 return -EINVAL; /* same return as native Linux */ 392 } 393 394 return 0; 395 } 396 397 /* 398 * Generate a Xen blkfront IO request from a blk layer request. Reads 399 * and writes are handled as expected. 400 * 401 * @req: a request struct 402 */ 403 static int blkif_queue_request(struct request *req) 404 { 405 struct blkfront_info *info = req->rq_disk->private_data; 406 struct blkif_request *ring_req; 407 unsigned long id; 408 unsigned int fsect, lsect; 409 int i, ref, n; 410 struct blkif_request_segment *segments = NULL; 411 412 /* 413 * Used to store if we are able to queue the request by just using 414 * existing persistent grants, or if we have to get new grants, 415 * as there are not sufficiently many free. 416 */ 417 bool new_persistent_gnts; 418 grant_ref_t gref_head; 419 struct grant *gnt_list_entry = NULL; 420 struct scatterlist *sg; 421 int nseg, max_grefs; 422 423 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 424 return 1; 425 426 max_grefs = req->nr_phys_segments; 427 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 428 /* 429 * If we are using indirect segments we need to account 430 * for the indirect grefs used in the request. 431 */ 432 max_grefs += INDIRECT_GREFS(req->nr_phys_segments); 433 434 /* Check if we have enough grants to allocate a requests */ 435 if (info->persistent_gnts_c < max_grefs) { 436 new_persistent_gnts = 1; 437 if (gnttab_alloc_grant_references( 438 max_grefs - info->persistent_gnts_c, 439 &gref_head) < 0) { 440 gnttab_request_free_callback( 441 &info->callback, 442 blkif_restart_queue_callback, 443 info, 444 max_grefs); 445 return 1; 446 } 447 } else 448 new_persistent_gnts = 0; 449 450 /* Fill out a communications ring structure. */ 451 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); 452 id = get_id_from_freelist(info); 453 info->shadow[id].request = req; 454 455 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) { 456 ring_req->operation = BLKIF_OP_DISCARD; 457 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 458 ring_req->u.discard.id = id; 459 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 460 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) 461 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 462 else 463 ring_req->u.discard.flag = 0; 464 } else { 465 BUG_ON(info->max_indirect_segments == 0 && 466 req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST); 467 BUG_ON(info->max_indirect_segments && 468 req->nr_phys_segments > info->max_indirect_segments); 469 nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg); 470 ring_req->u.rw.id = id; 471 if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) { 472 /* 473 * The indirect operation can only be a BLKIF_OP_READ or 474 * BLKIF_OP_WRITE 475 */ 476 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA)); 477 ring_req->operation = BLKIF_OP_INDIRECT; 478 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 479 BLKIF_OP_WRITE : BLKIF_OP_READ; 480 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 481 ring_req->u.indirect.handle = info->handle; 482 ring_req->u.indirect.nr_segments = nseg; 483 } else { 484 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 485 ring_req->u.rw.handle = info->handle; 486 ring_req->operation = rq_data_dir(req) ? 487 BLKIF_OP_WRITE : BLKIF_OP_READ; 488 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { 489 /* 490 * Ideally we can do an unordered flush-to-disk. In case the 491 * backend onlysupports barriers, use that. A barrier request 492 * a superset of FUA, so we can implement it the same 493 * way. (It's also a FLUSH+FUA, since it is 494 * guaranteed ordered WRT previous writes.) 495 */ 496 switch (info->feature_flush & 497 ((REQ_FLUSH|REQ_FUA))) { 498 case REQ_FLUSH|REQ_FUA: 499 ring_req->operation = 500 BLKIF_OP_WRITE_BARRIER; 501 break; 502 case REQ_FLUSH: 503 ring_req->operation = 504 BLKIF_OP_FLUSH_DISKCACHE; 505 break; 506 default: 507 ring_req->operation = 0; 508 } 509 } 510 ring_req->u.rw.nr_segments = nseg; 511 } 512 for_each_sg(info->shadow[id].sg, sg, nseg, i) { 513 fsect = sg->offset >> 9; 514 lsect = fsect + (sg->length >> 9) - 1; 515 516 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 517 (i % SEGS_PER_INDIRECT_FRAME == 0)) { 518 unsigned long uninitialized_var(pfn); 519 520 if (segments) 521 kunmap_atomic(segments); 522 523 n = i / SEGS_PER_INDIRECT_FRAME; 524 if (!info->feature_persistent) { 525 struct page *indirect_page; 526 527 /* Fetch a pre-allocated page to use for indirect grefs */ 528 BUG_ON(list_empty(&info->indirect_pages)); 529 indirect_page = list_first_entry(&info->indirect_pages, 530 struct page, lru); 531 list_del(&indirect_page->lru); 532 pfn = page_to_pfn(indirect_page); 533 } 534 gnt_list_entry = get_grant(&gref_head, pfn, info); 535 info->shadow[id].indirect_grants[n] = gnt_list_entry; 536 segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); 537 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 538 } 539 540 gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info); 541 ref = gnt_list_entry->gref; 542 543 info->shadow[id].grants_used[i] = gnt_list_entry; 544 545 if (rq_data_dir(req) && info->feature_persistent) { 546 char *bvec_data; 547 void *shared_data; 548 549 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 550 551 shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); 552 bvec_data = kmap_atomic(sg_page(sg)); 553 554 /* 555 * this does not wipe data stored outside the 556 * range sg->offset..sg->offset+sg->length. 557 * Therefore, blkback *could* see data from 558 * previous requests. This is OK as long as 559 * persistent grants are shared with just one 560 * domain. It may need refactoring if this 561 * changes 562 */ 563 memcpy(shared_data + sg->offset, 564 bvec_data + sg->offset, 565 sg->length); 566 567 kunmap_atomic(bvec_data); 568 kunmap_atomic(shared_data); 569 } 570 if (ring_req->operation != BLKIF_OP_INDIRECT) { 571 ring_req->u.rw.seg[i] = 572 (struct blkif_request_segment) { 573 .gref = ref, 574 .first_sect = fsect, 575 .last_sect = lsect }; 576 } else { 577 n = i % SEGS_PER_INDIRECT_FRAME; 578 segments[n] = 579 (struct blkif_request_segment) { 580 .gref = ref, 581 .first_sect = fsect, 582 .last_sect = lsect }; 583 } 584 } 585 if (segments) 586 kunmap_atomic(segments); 587 } 588 589 info->ring.req_prod_pvt++; 590 591 /* Keep a private copy so we can reissue requests when recovering. */ 592 info->shadow[id].req = *ring_req; 593 594 if (new_persistent_gnts) 595 gnttab_free_grant_references(gref_head); 596 597 return 0; 598 } 599 600 601 static inline void flush_requests(struct blkfront_info *info) 602 { 603 int notify; 604 605 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); 606 607 if (notify) 608 notify_remote_via_irq(info->irq); 609 } 610 611 static inline bool blkif_request_flush_invalid(struct request *req, 612 struct blkfront_info *info) 613 { 614 return ((req->cmd_type != REQ_TYPE_FS) || 615 ((req->cmd_flags & REQ_FLUSH) && 616 !(info->feature_flush & REQ_FLUSH)) || 617 ((req->cmd_flags & REQ_FUA) && 618 !(info->feature_flush & REQ_FUA))); 619 } 620 621 static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx, 622 const struct blk_mq_queue_data *qd) 623 { 624 struct blkfront_info *info = qd->rq->rq_disk->private_data; 625 626 blk_mq_start_request(qd->rq); 627 spin_lock_irq(&info->io_lock); 628 if (RING_FULL(&info->ring)) 629 goto out_busy; 630 631 if (blkif_request_flush_invalid(qd->rq, info)) 632 goto out_err; 633 634 if (blkif_queue_request(qd->rq)) 635 goto out_busy; 636 637 flush_requests(info); 638 spin_unlock_irq(&info->io_lock); 639 return BLK_MQ_RQ_QUEUE_OK; 640 641 out_err: 642 spin_unlock_irq(&info->io_lock); 643 return BLK_MQ_RQ_QUEUE_ERROR; 644 645 out_busy: 646 spin_unlock_irq(&info->io_lock); 647 blk_mq_stop_hw_queue(hctx); 648 return BLK_MQ_RQ_QUEUE_BUSY; 649 } 650 651 static struct blk_mq_ops blkfront_mq_ops = { 652 .queue_rq = blkif_queue_rq, 653 .map_queue = blk_mq_map_queue, 654 }; 655 656 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, 657 unsigned int physical_sector_size, 658 unsigned int segments) 659 { 660 struct request_queue *rq; 661 struct blkfront_info *info = gd->private_data; 662 663 memset(&info->tag_set, 0, sizeof(info->tag_set)); 664 info->tag_set.ops = &blkfront_mq_ops; 665 info->tag_set.nr_hw_queues = 1; 666 info->tag_set.queue_depth = BLK_RING_SIZE(info); 667 info->tag_set.numa_node = NUMA_NO_NODE; 668 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; 669 info->tag_set.cmd_size = 0; 670 info->tag_set.driver_data = info; 671 672 if (blk_mq_alloc_tag_set(&info->tag_set)) 673 return -1; 674 rq = blk_mq_init_queue(&info->tag_set); 675 if (IS_ERR(rq)) { 676 blk_mq_free_tag_set(&info->tag_set); 677 return -1; 678 } 679 680 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 681 682 if (info->feature_discard) { 683 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); 684 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 685 rq->limits.discard_granularity = info->discard_granularity; 686 rq->limits.discard_alignment = info->discard_alignment; 687 if (info->feature_secdiscard) 688 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq); 689 } 690 691 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 692 blk_queue_logical_block_size(rq, sector_size); 693 blk_queue_physical_block_size(rq, physical_sector_size); 694 blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512); 695 696 /* Each segment in a request is up to an aligned page in size. */ 697 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 698 blk_queue_max_segment_size(rq, PAGE_SIZE); 699 700 /* Ensure a merged request will fit in a single I/O ring slot. */ 701 blk_queue_max_segments(rq, segments); 702 703 /* Make sure buffer addresses are sector-aligned. */ 704 blk_queue_dma_alignment(rq, 511); 705 706 /* Make sure we don't use bounce buffers. */ 707 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); 708 709 gd->queue = rq; 710 711 return 0; 712 } 713 714 static const char *flush_info(unsigned int feature_flush) 715 { 716 switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) { 717 case REQ_FLUSH|REQ_FUA: 718 return "barrier: enabled;"; 719 case REQ_FLUSH: 720 return "flush diskcache: enabled;"; 721 default: 722 return "barrier or flush: disabled;"; 723 } 724 } 725 726 static void xlvbd_flush(struct blkfront_info *info) 727 { 728 blk_queue_flush(info->rq, info->feature_flush); 729 pr_info("blkfront: %s: %s %s %s %s %s\n", 730 info->gd->disk_name, flush_info(info->feature_flush), 731 "persistent grants:", info->feature_persistent ? 732 "enabled;" : "disabled;", "indirect descriptors:", 733 info->max_indirect_segments ? "enabled;" : "disabled;"); 734 } 735 736 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 737 { 738 int major; 739 major = BLKIF_MAJOR(vdevice); 740 *minor = BLKIF_MINOR(vdevice); 741 switch (major) { 742 case XEN_IDE0_MAJOR: 743 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 744 *minor = ((*minor / 64) * PARTS_PER_DISK) + 745 EMULATED_HD_DISK_MINOR_OFFSET; 746 break; 747 case XEN_IDE1_MAJOR: 748 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 749 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 750 EMULATED_HD_DISK_MINOR_OFFSET; 751 break; 752 case XEN_SCSI_DISK0_MAJOR: 753 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 754 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 755 break; 756 case XEN_SCSI_DISK1_MAJOR: 757 case XEN_SCSI_DISK2_MAJOR: 758 case XEN_SCSI_DISK3_MAJOR: 759 case XEN_SCSI_DISK4_MAJOR: 760 case XEN_SCSI_DISK5_MAJOR: 761 case XEN_SCSI_DISK6_MAJOR: 762 case XEN_SCSI_DISK7_MAJOR: 763 *offset = (*minor / PARTS_PER_DISK) + 764 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 765 EMULATED_SD_DISK_NAME_OFFSET; 766 *minor = *minor + 767 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 768 EMULATED_SD_DISK_MINOR_OFFSET; 769 break; 770 case XEN_SCSI_DISK8_MAJOR: 771 case XEN_SCSI_DISK9_MAJOR: 772 case XEN_SCSI_DISK10_MAJOR: 773 case XEN_SCSI_DISK11_MAJOR: 774 case XEN_SCSI_DISK12_MAJOR: 775 case XEN_SCSI_DISK13_MAJOR: 776 case XEN_SCSI_DISK14_MAJOR: 777 case XEN_SCSI_DISK15_MAJOR: 778 *offset = (*minor / PARTS_PER_DISK) + 779 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 780 EMULATED_SD_DISK_NAME_OFFSET; 781 *minor = *minor + 782 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 783 EMULATED_SD_DISK_MINOR_OFFSET; 784 break; 785 case XENVBD_MAJOR: 786 *offset = *minor / PARTS_PER_DISK; 787 break; 788 default: 789 printk(KERN_WARNING "blkfront: your disk configuration is " 790 "incorrect, please use an xvd device instead\n"); 791 return -ENODEV; 792 } 793 return 0; 794 } 795 796 static char *encode_disk_name(char *ptr, unsigned int n) 797 { 798 if (n >= 26) 799 ptr = encode_disk_name(ptr, n / 26 - 1); 800 *ptr = 'a' + n % 26; 801 return ptr + 1; 802 } 803 804 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 805 struct blkfront_info *info, 806 u16 vdisk_info, u16 sector_size, 807 unsigned int physical_sector_size) 808 { 809 struct gendisk *gd; 810 int nr_minors = 1; 811 int err; 812 unsigned int offset; 813 int minor; 814 int nr_parts; 815 char *ptr; 816 817 BUG_ON(info->gd != NULL); 818 BUG_ON(info->rq != NULL); 819 820 if ((info->vdevice>>EXT_SHIFT) > 1) { 821 /* this is above the extended range; something is wrong */ 822 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 823 return -ENODEV; 824 } 825 826 if (!VDEV_IS_EXTENDED(info->vdevice)) { 827 err = xen_translate_vdev(info->vdevice, &minor, &offset); 828 if (err) 829 return err; 830 nr_parts = PARTS_PER_DISK; 831 } else { 832 minor = BLKIF_MINOR_EXT(info->vdevice); 833 nr_parts = PARTS_PER_EXT_DISK; 834 offset = minor / nr_parts; 835 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 836 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 837 "emulated IDE disks,\n\t choose an xvd device name" 838 "from xvde on\n", info->vdevice); 839 } 840 if (minor >> MINORBITS) { 841 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 842 info->vdevice, minor); 843 return -ENODEV; 844 } 845 846 if ((minor % nr_parts) == 0) 847 nr_minors = nr_parts; 848 849 err = xlbd_reserve_minors(minor, nr_minors); 850 if (err) 851 goto out; 852 err = -ENODEV; 853 854 gd = alloc_disk(nr_minors); 855 if (gd == NULL) 856 goto release; 857 858 strcpy(gd->disk_name, DEV_NAME); 859 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 860 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 861 if (nr_minors > 1) 862 *ptr = 0; 863 else 864 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 865 "%d", minor & (nr_parts - 1)); 866 867 gd->major = XENVBD_MAJOR; 868 gd->first_minor = minor; 869 gd->fops = &xlvbd_block_fops; 870 gd->private_data = info; 871 gd->driverfs_dev = &(info->xbdev->dev); 872 set_capacity(gd, capacity); 873 874 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size, 875 info->max_indirect_segments ? : 876 BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 877 del_gendisk(gd); 878 goto release; 879 } 880 881 info->rq = gd->queue; 882 info->gd = gd; 883 884 xlvbd_flush(info); 885 886 if (vdisk_info & VDISK_READONLY) 887 set_disk_ro(gd, 1); 888 889 if (vdisk_info & VDISK_REMOVABLE) 890 gd->flags |= GENHD_FL_REMOVABLE; 891 892 if (vdisk_info & VDISK_CDROM) 893 gd->flags |= GENHD_FL_CD; 894 895 return 0; 896 897 release: 898 xlbd_release_minors(minor, nr_minors); 899 out: 900 return err; 901 } 902 903 static void xlvbd_release_gendisk(struct blkfront_info *info) 904 { 905 unsigned int minor, nr_minors; 906 907 if (info->rq == NULL) 908 return; 909 910 /* No more blkif_request(). */ 911 blk_mq_stop_hw_queues(info->rq); 912 913 /* No more gnttab callback work. */ 914 gnttab_cancel_free_callback(&info->callback); 915 916 /* Flush gnttab callback work. Must be done with no locks held. */ 917 flush_work(&info->work); 918 919 del_gendisk(info->gd); 920 921 minor = info->gd->first_minor; 922 nr_minors = info->gd->minors; 923 xlbd_release_minors(minor, nr_minors); 924 925 blk_cleanup_queue(info->rq); 926 blk_mq_free_tag_set(&info->tag_set); 927 info->rq = NULL; 928 929 put_disk(info->gd); 930 info->gd = NULL; 931 } 932 933 /* Must be called with io_lock holded */ 934 static void kick_pending_request_queues(struct blkfront_info *info) 935 { 936 if (!RING_FULL(&info->ring)) 937 blk_mq_start_stopped_hw_queues(info->rq, true); 938 } 939 940 static void blkif_restart_queue(struct work_struct *work) 941 { 942 struct blkfront_info *info = container_of(work, struct blkfront_info, work); 943 944 spin_lock_irq(&info->io_lock); 945 if (info->connected == BLKIF_STATE_CONNECTED) 946 kick_pending_request_queues(info); 947 spin_unlock_irq(&info->io_lock); 948 } 949 950 static void blkif_free(struct blkfront_info *info, int suspend) 951 { 952 struct grant *persistent_gnt; 953 struct grant *n; 954 int i, j, segs; 955 956 /* Prevent new requests being issued until we fix things up. */ 957 spin_lock_irq(&info->io_lock); 958 info->connected = suspend ? 959 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 960 /* No more blkif_request(). */ 961 if (info->rq) 962 blk_mq_stop_hw_queues(info->rq); 963 964 /* Remove all persistent grants */ 965 if (!list_empty(&info->grants)) { 966 list_for_each_entry_safe(persistent_gnt, n, 967 &info->grants, node) { 968 list_del(&persistent_gnt->node); 969 if (persistent_gnt->gref != GRANT_INVALID_REF) { 970 gnttab_end_foreign_access(persistent_gnt->gref, 971 0, 0UL); 972 info->persistent_gnts_c--; 973 } 974 if (info->feature_persistent) 975 __free_page(pfn_to_page(persistent_gnt->pfn)); 976 kfree(persistent_gnt); 977 } 978 } 979 BUG_ON(info->persistent_gnts_c != 0); 980 981 /* 982 * Remove indirect pages, this only happens when using indirect 983 * descriptors but not persistent grants 984 */ 985 if (!list_empty(&info->indirect_pages)) { 986 struct page *indirect_page, *n; 987 988 BUG_ON(info->feature_persistent); 989 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 990 list_del(&indirect_page->lru); 991 __free_page(indirect_page); 992 } 993 } 994 995 for (i = 0; i < BLK_RING_SIZE(info); i++) { 996 /* 997 * Clear persistent grants present in requests already 998 * on the shared ring 999 */ 1000 if (!info->shadow[i].request) 1001 goto free_shadow; 1002 1003 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 1004 info->shadow[i].req.u.indirect.nr_segments : 1005 info->shadow[i].req.u.rw.nr_segments; 1006 for (j = 0; j < segs; j++) { 1007 persistent_gnt = info->shadow[i].grants_used[j]; 1008 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1009 if (info->feature_persistent) 1010 __free_page(pfn_to_page(persistent_gnt->pfn)); 1011 kfree(persistent_gnt); 1012 } 1013 1014 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT) 1015 /* 1016 * If this is not an indirect operation don't try to 1017 * free indirect segments 1018 */ 1019 goto free_shadow; 1020 1021 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 1022 persistent_gnt = info->shadow[i].indirect_grants[j]; 1023 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1024 __free_page(pfn_to_page(persistent_gnt->pfn)); 1025 kfree(persistent_gnt); 1026 } 1027 1028 free_shadow: 1029 kfree(info->shadow[i].grants_used); 1030 info->shadow[i].grants_used = NULL; 1031 kfree(info->shadow[i].indirect_grants); 1032 info->shadow[i].indirect_grants = NULL; 1033 kfree(info->shadow[i].sg); 1034 info->shadow[i].sg = NULL; 1035 } 1036 1037 /* No more gnttab callback work. */ 1038 gnttab_cancel_free_callback(&info->callback); 1039 spin_unlock_irq(&info->io_lock); 1040 1041 /* Flush gnttab callback work. Must be done with no locks held. */ 1042 flush_work(&info->work); 1043 1044 /* Free resources associated with old device channel. */ 1045 for (i = 0; i < info->nr_ring_pages; i++) { 1046 if (info->ring_ref[i] != GRANT_INVALID_REF) { 1047 gnttab_end_foreign_access(info->ring_ref[i], 0, 0); 1048 info->ring_ref[i] = GRANT_INVALID_REF; 1049 } 1050 } 1051 free_pages((unsigned long)info->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE)); 1052 info->ring.sring = NULL; 1053 1054 if (info->irq) 1055 unbind_from_irqhandler(info->irq, info); 1056 info->evtchn = info->irq = 0; 1057 1058 } 1059 1060 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, 1061 struct blkif_response *bret) 1062 { 1063 int i = 0; 1064 struct scatterlist *sg; 1065 char *bvec_data; 1066 void *shared_data; 1067 int nseg; 1068 1069 nseg = s->req.operation == BLKIF_OP_INDIRECT ? 1070 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1071 1072 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { 1073 for_each_sg(s->sg, sg, nseg, i) { 1074 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1075 shared_data = kmap_atomic( 1076 pfn_to_page(s->grants_used[i]->pfn)); 1077 bvec_data = kmap_atomic(sg_page(sg)); 1078 memcpy(bvec_data + sg->offset, 1079 shared_data + sg->offset, 1080 sg->length); 1081 kunmap_atomic(bvec_data); 1082 kunmap_atomic(shared_data); 1083 } 1084 } 1085 /* Add the persistent grant into the list of free grants */ 1086 for (i = 0; i < nseg; i++) { 1087 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) { 1088 /* 1089 * If the grant is still mapped by the backend (the 1090 * backend has chosen to make this grant persistent) 1091 * we add it at the head of the list, so it will be 1092 * reused first. 1093 */ 1094 if (!info->feature_persistent) 1095 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1096 s->grants_used[i]->gref); 1097 list_add(&s->grants_used[i]->node, &info->grants); 1098 info->persistent_gnts_c++; 1099 } else { 1100 /* 1101 * If the grant is not mapped by the backend we end the 1102 * foreign access and add it to the tail of the list, 1103 * so it will not be picked again unless we run out of 1104 * persistent grants. 1105 */ 1106 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); 1107 s->grants_used[i]->gref = GRANT_INVALID_REF; 1108 list_add_tail(&s->grants_used[i]->node, &info->grants); 1109 } 1110 } 1111 if (s->req.operation == BLKIF_OP_INDIRECT) { 1112 for (i = 0; i < INDIRECT_GREFS(nseg); i++) { 1113 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { 1114 if (!info->feature_persistent) 1115 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1116 s->indirect_grants[i]->gref); 1117 list_add(&s->indirect_grants[i]->node, &info->grants); 1118 info->persistent_gnts_c++; 1119 } else { 1120 struct page *indirect_page; 1121 1122 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); 1123 /* 1124 * Add the used indirect page back to the list of 1125 * available pages for indirect grefs. 1126 */ 1127 if (!info->feature_persistent) { 1128 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn); 1129 list_add(&indirect_page->lru, &info->indirect_pages); 1130 } 1131 s->indirect_grants[i]->gref = GRANT_INVALID_REF; 1132 list_add_tail(&s->indirect_grants[i]->node, &info->grants); 1133 } 1134 } 1135 } 1136 } 1137 1138 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1139 { 1140 struct request *req; 1141 struct blkif_response *bret; 1142 RING_IDX i, rp; 1143 unsigned long flags; 1144 struct blkfront_info *info = (struct blkfront_info *)dev_id; 1145 int error; 1146 1147 spin_lock_irqsave(&info->io_lock, flags); 1148 1149 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { 1150 spin_unlock_irqrestore(&info->io_lock, flags); 1151 return IRQ_HANDLED; 1152 } 1153 1154 again: 1155 rp = info->ring.sring->rsp_prod; 1156 rmb(); /* Ensure we see queued responses up to 'rp'. */ 1157 1158 for (i = info->ring.rsp_cons; i != rp; i++) { 1159 unsigned long id; 1160 1161 bret = RING_GET_RESPONSE(&info->ring, i); 1162 id = bret->id; 1163 /* 1164 * The backend has messed up and given us an id that we would 1165 * never have given to it (we stamp it up to BLK_RING_SIZE - 1166 * look in get_id_from_freelist. 1167 */ 1168 if (id >= BLK_RING_SIZE(info)) { 1169 WARN(1, "%s: response to %s has incorrect id (%ld)\n", 1170 info->gd->disk_name, op_name(bret->operation), id); 1171 /* We can't safely get the 'struct request' as 1172 * the id is busted. */ 1173 continue; 1174 } 1175 req = info->shadow[id].request; 1176 1177 if (bret->operation != BLKIF_OP_DISCARD) 1178 blkif_completion(&info->shadow[id], info, bret); 1179 1180 if (add_id_to_freelist(info, id)) { 1181 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1182 info->gd->disk_name, op_name(bret->operation), id); 1183 continue; 1184 } 1185 1186 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; 1187 switch (bret->operation) { 1188 case BLKIF_OP_DISCARD: 1189 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1190 struct request_queue *rq = info->rq; 1191 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1192 info->gd->disk_name, op_name(bret->operation)); 1193 error = -EOPNOTSUPP; 1194 info->feature_discard = 0; 1195 info->feature_secdiscard = 0; 1196 queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 1197 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq); 1198 } 1199 blk_mq_complete_request(req, error); 1200 break; 1201 case BLKIF_OP_FLUSH_DISKCACHE: 1202 case BLKIF_OP_WRITE_BARRIER: 1203 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1204 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1205 info->gd->disk_name, op_name(bret->operation)); 1206 error = -EOPNOTSUPP; 1207 } 1208 if (unlikely(bret->status == BLKIF_RSP_ERROR && 1209 info->shadow[id].req.u.rw.nr_segments == 0)) { 1210 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", 1211 info->gd->disk_name, op_name(bret->operation)); 1212 error = -EOPNOTSUPP; 1213 } 1214 if (unlikely(error)) { 1215 if (error == -EOPNOTSUPP) 1216 error = 0; 1217 info->feature_flush = 0; 1218 xlvbd_flush(info); 1219 } 1220 /* fall through */ 1221 case BLKIF_OP_READ: 1222 case BLKIF_OP_WRITE: 1223 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 1224 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 1225 "request: %x\n", bret->status); 1226 1227 blk_mq_complete_request(req, error); 1228 break; 1229 default: 1230 BUG(); 1231 } 1232 } 1233 1234 info->ring.rsp_cons = i; 1235 1236 if (i != info->ring.req_prod_pvt) { 1237 int more_to_do; 1238 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 1239 if (more_to_do) 1240 goto again; 1241 } else 1242 info->ring.sring->rsp_event = i + 1; 1243 1244 kick_pending_request_queues(info); 1245 1246 spin_unlock_irqrestore(&info->io_lock, flags); 1247 1248 return IRQ_HANDLED; 1249 } 1250 1251 1252 static int setup_blkring(struct xenbus_device *dev, 1253 struct blkfront_info *info) 1254 { 1255 struct blkif_sring *sring; 1256 int err, i; 1257 unsigned long ring_size = info->nr_ring_pages * PAGE_SIZE; 1258 grant_ref_t gref[XENBUS_MAX_RING_PAGES]; 1259 1260 for (i = 0; i < info->nr_ring_pages; i++) 1261 info->ring_ref[i] = GRANT_INVALID_REF; 1262 1263 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH, 1264 get_order(ring_size)); 1265 if (!sring) { 1266 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1267 return -ENOMEM; 1268 } 1269 SHARED_RING_INIT(sring); 1270 FRONT_RING_INIT(&info->ring, sring, ring_size); 1271 1272 err = xenbus_grant_ring(dev, info->ring.sring, info->nr_ring_pages, gref); 1273 if (err < 0) { 1274 free_pages((unsigned long)sring, get_order(ring_size)); 1275 info->ring.sring = NULL; 1276 goto fail; 1277 } 1278 for (i = 0; i < info->nr_ring_pages; i++) 1279 info->ring_ref[i] = gref[i]; 1280 1281 err = xenbus_alloc_evtchn(dev, &info->evtchn); 1282 if (err) 1283 goto fail; 1284 1285 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0, 1286 "blkif", info); 1287 if (err <= 0) { 1288 xenbus_dev_fatal(dev, err, 1289 "bind_evtchn_to_irqhandler failed"); 1290 goto fail; 1291 } 1292 info->irq = err; 1293 1294 return 0; 1295 fail: 1296 blkif_free(info, 0); 1297 return err; 1298 } 1299 1300 1301 /* Common code used when first setting up, and when resuming. */ 1302 static int talk_to_blkback(struct xenbus_device *dev, 1303 struct blkfront_info *info) 1304 { 1305 const char *message = NULL; 1306 struct xenbus_transaction xbt; 1307 int err, i; 1308 unsigned int max_page_order = 0; 1309 unsigned int ring_page_order = 0; 1310 1311 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1312 "max-ring-page-order", "%u", &max_page_order); 1313 if (err != 1) 1314 info->nr_ring_pages = 1; 1315 else { 1316 ring_page_order = min(xen_blkif_max_ring_order, max_page_order); 1317 info->nr_ring_pages = 1 << ring_page_order; 1318 } 1319 1320 /* Create shared ring, alloc event channel. */ 1321 err = setup_blkring(dev, info); 1322 if (err) 1323 goto out; 1324 1325 again: 1326 err = xenbus_transaction_start(&xbt); 1327 if (err) { 1328 xenbus_dev_fatal(dev, err, "starting transaction"); 1329 goto destroy_blkring; 1330 } 1331 1332 if (info->nr_ring_pages == 1) { 1333 err = xenbus_printf(xbt, dev->nodename, 1334 "ring-ref", "%u", info->ring_ref[0]); 1335 if (err) { 1336 message = "writing ring-ref"; 1337 goto abort_transaction; 1338 } 1339 } else { 1340 err = xenbus_printf(xbt, dev->nodename, 1341 "ring-page-order", "%u", ring_page_order); 1342 if (err) { 1343 message = "writing ring-page-order"; 1344 goto abort_transaction; 1345 } 1346 1347 for (i = 0; i < info->nr_ring_pages; i++) { 1348 char ring_ref_name[RINGREF_NAME_LEN]; 1349 1350 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 1351 err = xenbus_printf(xbt, dev->nodename, ring_ref_name, 1352 "%u", info->ring_ref[i]); 1353 if (err) { 1354 message = "writing ring-ref"; 1355 goto abort_transaction; 1356 } 1357 } 1358 } 1359 err = xenbus_printf(xbt, dev->nodename, 1360 "event-channel", "%u", info->evtchn); 1361 if (err) { 1362 message = "writing event-channel"; 1363 goto abort_transaction; 1364 } 1365 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1366 XEN_IO_PROTO_ABI_NATIVE); 1367 if (err) { 1368 message = "writing protocol"; 1369 goto abort_transaction; 1370 } 1371 err = xenbus_printf(xbt, dev->nodename, 1372 "feature-persistent", "%u", 1); 1373 if (err) 1374 dev_warn(&dev->dev, 1375 "writing persistent grants feature to xenbus"); 1376 1377 err = xenbus_transaction_end(xbt, 0); 1378 if (err) { 1379 if (err == -EAGAIN) 1380 goto again; 1381 xenbus_dev_fatal(dev, err, "completing transaction"); 1382 goto destroy_blkring; 1383 } 1384 1385 for (i = 0; i < BLK_RING_SIZE(info); i++) 1386 info->shadow[i].req.u.rw.id = i+1; 1387 info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 1388 xenbus_switch_state(dev, XenbusStateInitialised); 1389 1390 return 0; 1391 1392 abort_transaction: 1393 xenbus_transaction_end(xbt, 1); 1394 if (message) 1395 xenbus_dev_fatal(dev, err, "%s", message); 1396 destroy_blkring: 1397 blkif_free(info, 0); 1398 out: 1399 return err; 1400 } 1401 1402 /** 1403 * Entry point to this code when a new device is created. Allocate the basic 1404 * structures and the ring buffer for communication with the backend, and 1405 * inform the backend of the appropriate details for those. Switch to 1406 * Initialised state. 1407 */ 1408 static int blkfront_probe(struct xenbus_device *dev, 1409 const struct xenbus_device_id *id) 1410 { 1411 int err, vdevice; 1412 struct blkfront_info *info; 1413 1414 /* FIXME: Use dynamic device id if this is not set. */ 1415 err = xenbus_scanf(XBT_NIL, dev->nodename, 1416 "virtual-device", "%i", &vdevice); 1417 if (err != 1) { 1418 /* go looking in the extended area instead */ 1419 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1420 "%i", &vdevice); 1421 if (err != 1) { 1422 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1423 return err; 1424 } 1425 } 1426 1427 if (xen_hvm_domain()) { 1428 char *type; 1429 int len; 1430 /* no unplug has been done: do not hook devices != xen vbds */ 1431 if (xen_has_pv_and_legacy_disk_devices()) { 1432 int major; 1433 1434 if (!VDEV_IS_EXTENDED(vdevice)) 1435 major = BLKIF_MAJOR(vdevice); 1436 else 1437 major = XENVBD_MAJOR; 1438 1439 if (major != XENVBD_MAJOR) { 1440 printk(KERN_INFO 1441 "%s: HVM does not support vbd %d as xen block device\n", 1442 __func__, vdevice); 1443 return -ENODEV; 1444 } 1445 } 1446 /* do not create a PV cdrom device if we are an HVM guest */ 1447 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1448 if (IS_ERR(type)) 1449 return -ENODEV; 1450 if (strncmp(type, "cdrom", 5) == 0) { 1451 kfree(type); 1452 return -ENODEV; 1453 } 1454 kfree(type); 1455 } 1456 info = kzalloc(sizeof(*info), GFP_KERNEL); 1457 if (!info) { 1458 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1459 return -ENOMEM; 1460 } 1461 1462 mutex_init(&info->mutex); 1463 spin_lock_init(&info->io_lock); 1464 info->xbdev = dev; 1465 info->vdevice = vdevice; 1466 INIT_LIST_HEAD(&info->grants); 1467 INIT_LIST_HEAD(&info->indirect_pages); 1468 info->persistent_gnts_c = 0; 1469 info->connected = BLKIF_STATE_DISCONNECTED; 1470 INIT_WORK(&info->work, blkif_restart_queue); 1471 1472 /* Front end dir is a number, which is used as the id. */ 1473 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1474 dev_set_drvdata(&dev->dev, info); 1475 1476 return 0; 1477 } 1478 1479 static void split_bio_end(struct bio *bio) 1480 { 1481 struct split_bio *split_bio = bio->bi_private; 1482 1483 if (atomic_dec_and_test(&split_bio->pending)) { 1484 split_bio->bio->bi_phys_segments = 0; 1485 split_bio->bio->bi_error = bio->bi_error; 1486 bio_endio(split_bio->bio); 1487 kfree(split_bio); 1488 } 1489 bio_put(bio); 1490 } 1491 1492 static int blkif_recover(struct blkfront_info *info) 1493 { 1494 int i; 1495 struct request *req, *n; 1496 struct blk_shadow *copy; 1497 int rc; 1498 struct bio *bio, *cloned_bio; 1499 struct bio_list bio_list, merge_bio; 1500 unsigned int segs, offset; 1501 int pending, size; 1502 struct split_bio *split_bio; 1503 struct list_head requests; 1504 1505 /* Stage 1: Make a safe copy of the shadow state. */ 1506 copy = kmemdup(info->shadow, sizeof(info->shadow), 1507 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); 1508 if (!copy) 1509 return -ENOMEM; 1510 1511 /* Stage 2: Set up free list. */ 1512 memset(&info->shadow, 0, sizeof(info->shadow)); 1513 for (i = 0; i < BLK_RING_SIZE(info); i++) 1514 info->shadow[i].req.u.rw.id = i+1; 1515 info->shadow_free = info->ring.req_prod_pvt; 1516 info->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 1517 1518 rc = blkfront_gather_backend_features(info); 1519 if (rc) { 1520 kfree(copy); 1521 return rc; 1522 } 1523 1524 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 1525 blk_queue_max_segments(info->rq, segs); 1526 bio_list_init(&bio_list); 1527 INIT_LIST_HEAD(&requests); 1528 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1529 /* Not in use? */ 1530 if (!copy[i].request) 1531 continue; 1532 1533 /* 1534 * Get the bios in the request so we can re-queue them. 1535 */ 1536 if (copy[i].request->cmd_flags & 1537 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1538 /* 1539 * Flush operations don't contain bios, so 1540 * we need to requeue the whole request 1541 */ 1542 list_add(©[i].request->queuelist, &requests); 1543 continue; 1544 } 1545 merge_bio.head = copy[i].request->bio; 1546 merge_bio.tail = copy[i].request->biotail; 1547 bio_list_merge(&bio_list, &merge_bio); 1548 copy[i].request->bio = NULL; 1549 blk_end_request_all(copy[i].request, 0); 1550 } 1551 1552 kfree(copy); 1553 1554 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1555 1556 spin_lock_irq(&info->io_lock); 1557 1558 /* Now safe for us to use the shared ring */ 1559 info->connected = BLKIF_STATE_CONNECTED; 1560 1561 /* Kick any other new requests queued since we resumed */ 1562 kick_pending_request_queues(info); 1563 1564 list_for_each_entry_safe(req, n, &requests, queuelist) { 1565 /* Requeue pending requests (flush or discard) */ 1566 list_del_init(&req->queuelist); 1567 BUG_ON(req->nr_phys_segments > segs); 1568 blk_mq_requeue_request(req); 1569 } 1570 spin_unlock_irq(&info->io_lock); 1571 blk_mq_kick_requeue_list(info->rq); 1572 1573 while ((bio = bio_list_pop(&bio_list)) != NULL) { 1574 /* Traverse the list of pending bios and re-queue them */ 1575 if (bio_segments(bio) > segs) { 1576 /* 1577 * This bio has more segments than what we can 1578 * handle, we have to split it. 1579 */ 1580 pending = (bio_segments(bio) + segs - 1) / segs; 1581 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO); 1582 BUG_ON(split_bio == NULL); 1583 atomic_set(&split_bio->pending, pending); 1584 split_bio->bio = bio; 1585 for (i = 0; i < pending; i++) { 1586 offset = (i * segs * PAGE_SIZE) >> 9; 1587 size = min((unsigned int)(segs * PAGE_SIZE) >> 9, 1588 (unsigned int)bio_sectors(bio) - offset); 1589 cloned_bio = bio_clone(bio, GFP_NOIO); 1590 BUG_ON(cloned_bio == NULL); 1591 bio_trim(cloned_bio, offset, size); 1592 cloned_bio->bi_private = split_bio; 1593 cloned_bio->bi_end_io = split_bio_end; 1594 submit_bio(cloned_bio->bi_rw, cloned_bio); 1595 } 1596 /* 1597 * Now we have to wait for all those smaller bios to 1598 * end, so we can also end the "parent" bio. 1599 */ 1600 continue; 1601 } 1602 /* We don't need to split this bio */ 1603 submit_bio(bio->bi_rw, bio); 1604 } 1605 1606 return 0; 1607 } 1608 1609 /** 1610 * We are reconnecting to the backend, due to a suspend/resume, or a backend 1611 * driver restart. We tear down our blkif structure and recreate it, but 1612 * leave the device-layer structures intact so that this is transparent to the 1613 * rest of the kernel. 1614 */ 1615 static int blkfront_resume(struct xenbus_device *dev) 1616 { 1617 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1618 int err; 1619 1620 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 1621 1622 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 1623 1624 err = talk_to_blkback(dev, info); 1625 1626 /* 1627 * We have to wait for the backend to switch to 1628 * connected state, since we want to read which 1629 * features it supports. 1630 */ 1631 1632 return err; 1633 } 1634 1635 static void 1636 blkfront_closing(struct blkfront_info *info) 1637 { 1638 struct xenbus_device *xbdev = info->xbdev; 1639 struct block_device *bdev = NULL; 1640 1641 mutex_lock(&info->mutex); 1642 1643 if (xbdev->state == XenbusStateClosing) { 1644 mutex_unlock(&info->mutex); 1645 return; 1646 } 1647 1648 if (info->gd) 1649 bdev = bdget_disk(info->gd, 0); 1650 1651 mutex_unlock(&info->mutex); 1652 1653 if (!bdev) { 1654 xenbus_frontend_closed(xbdev); 1655 return; 1656 } 1657 1658 mutex_lock(&bdev->bd_mutex); 1659 1660 if (bdev->bd_openers) { 1661 xenbus_dev_error(xbdev, -EBUSY, 1662 "Device in use; refusing to close"); 1663 xenbus_switch_state(xbdev, XenbusStateClosing); 1664 } else { 1665 xlvbd_release_gendisk(info); 1666 xenbus_frontend_closed(xbdev); 1667 } 1668 1669 mutex_unlock(&bdev->bd_mutex); 1670 bdput(bdev); 1671 } 1672 1673 static void blkfront_setup_discard(struct blkfront_info *info) 1674 { 1675 int err; 1676 unsigned int discard_granularity; 1677 unsigned int discard_alignment; 1678 unsigned int discard_secure; 1679 1680 info->feature_discard = 1; 1681 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1682 "discard-granularity", "%u", &discard_granularity, 1683 "discard-alignment", "%u", &discard_alignment, 1684 NULL); 1685 if (!err) { 1686 info->discard_granularity = discard_granularity; 1687 info->discard_alignment = discard_alignment; 1688 } 1689 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1690 "discard-secure", "%d", &discard_secure, 1691 NULL); 1692 if (!err) 1693 info->feature_secdiscard = !!discard_secure; 1694 } 1695 1696 static int blkfront_setup_indirect(struct blkfront_info *info) 1697 { 1698 unsigned int segs; 1699 int err, i; 1700 1701 if (info->max_indirect_segments == 0) 1702 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST; 1703 else 1704 segs = info->max_indirect_segments; 1705 1706 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE(info)); 1707 if (err) 1708 goto out_of_memory; 1709 1710 if (!info->feature_persistent && info->max_indirect_segments) { 1711 /* 1712 * We are using indirect descriptors but not persistent 1713 * grants, we need to allocate a set of pages that can be 1714 * used for mapping indirect grefs 1715 */ 1716 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE(info); 1717 1718 BUG_ON(!list_empty(&info->indirect_pages)); 1719 for (i = 0; i < num; i++) { 1720 struct page *indirect_page = alloc_page(GFP_NOIO); 1721 if (!indirect_page) 1722 goto out_of_memory; 1723 list_add(&indirect_page->lru, &info->indirect_pages); 1724 } 1725 } 1726 1727 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1728 info->shadow[i].grants_used = kzalloc( 1729 sizeof(info->shadow[i].grants_used[0]) * segs, 1730 GFP_NOIO); 1731 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO); 1732 if (info->max_indirect_segments) 1733 info->shadow[i].indirect_grants = kzalloc( 1734 sizeof(info->shadow[i].indirect_grants[0]) * 1735 INDIRECT_GREFS(segs), 1736 GFP_NOIO); 1737 if ((info->shadow[i].grants_used == NULL) || 1738 (info->shadow[i].sg == NULL) || 1739 (info->max_indirect_segments && 1740 (info->shadow[i].indirect_grants == NULL))) 1741 goto out_of_memory; 1742 sg_init_table(info->shadow[i].sg, segs); 1743 } 1744 1745 1746 return 0; 1747 1748 out_of_memory: 1749 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1750 kfree(info->shadow[i].grants_used); 1751 info->shadow[i].grants_used = NULL; 1752 kfree(info->shadow[i].sg); 1753 info->shadow[i].sg = NULL; 1754 kfree(info->shadow[i].indirect_grants); 1755 info->shadow[i].indirect_grants = NULL; 1756 } 1757 if (!list_empty(&info->indirect_pages)) { 1758 struct page *indirect_page, *n; 1759 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 1760 list_del(&indirect_page->lru); 1761 __free_page(indirect_page); 1762 } 1763 } 1764 return -ENOMEM; 1765 } 1766 1767 /* 1768 * Gather all backend feature-* 1769 */ 1770 static int blkfront_gather_backend_features(struct blkfront_info *info) 1771 { 1772 int err; 1773 int barrier, flush, discard, persistent; 1774 unsigned int indirect_segments; 1775 1776 info->feature_flush = 0; 1777 1778 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1779 "feature-barrier", "%d", &barrier, 1780 NULL); 1781 1782 /* 1783 * If there's no "feature-barrier" defined, then it means 1784 * we're dealing with a very old backend which writes 1785 * synchronously; nothing to do. 1786 * 1787 * If there are barriers, then we use flush. 1788 */ 1789 if (!err && barrier) 1790 info->feature_flush = REQ_FLUSH | REQ_FUA; 1791 /* 1792 * And if there is "feature-flush-cache" use that above 1793 * barriers. 1794 */ 1795 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1796 "feature-flush-cache", "%d", &flush, 1797 NULL); 1798 1799 if (!err && flush) 1800 info->feature_flush = REQ_FLUSH; 1801 1802 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1803 "feature-discard", "%d", &discard, 1804 NULL); 1805 1806 if (!err && discard) 1807 blkfront_setup_discard(info); 1808 1809 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1810 "feature-persistent", "%u", &persistent, 1811 NULL); 1812 if (err) 1813 info->feature_persistent = 0; 1814 else 1815 info->feature_persistent = persistent; 1816 1817 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1818 "feature-max-indirect-segments", "%u", &indirect_segments, 1819 NULL); 1820 if (err) 1821 info->max_indirect_segments = 0; 1822 else 1823 info->max_indirect_segments = min(indirect_segments, 1824 xen_blkif_max_segments); 1825 1826 return blkfront_setup_indirect(info); 1827 } 1828 1829 /* 1830 * Invoked when the backend is finally 'ready' (and has told produced 1831 * the details about the physical device - #sectors, size, etc). 1832 */ 1833 static void blkfront_connect(struct blkfront_info *info) 1834 { 1835 unsigned long long sectors; 1836 unsigned long sector_size; 1837 unsigned int physical_sector_size; 1838 unsigned int binfo; 1839 int err; 1840 1841 switch (info->connected) { 1842 case BLKIF_STATE_CONNECTED: 1843 /* 1844 * Potentially, the back-end may be signalling 1845 * a capacity change; update the capacity. 1846 */ 1847 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1848 "sectors", "%Lu", §ors); 1849 if (XENBUS_EXIST_ERR(err)) 1850 return; 1851 printk(KERN_INFO "Setting capacity to %Lu\n", 1852 sectors); 1853 set_capacity(info->gd, sectors); 1854 revalidate_disk(info->gd); 1855 1856 return; 1857 case BLKIF_STATE_SUSPENDED: 1858 /* 1859 * If we are recovering from suspension, we need to wait 1860 * for the backend to announce it's features before 1861 * reconnecting, at least we need to know if the backend 1862 * supports indirect descriptors, and how many. 1863 */ 1864 blkif_recover(info); 1865 return; 1866 1867 default: 1868 break; 1869 } 1870 1871 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 1872 __func__, info->xbdev->otherend); 1873 1874 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1875 "sectors", "%llu", §ors, 1876 "info", "%u", &binfo, 1877 "sector-size", "%lu", §or_size, 1878 NULL); 1879 if (err) { 1880 xenbus_dev_fatal(info->xbdev, err, 1881 "reading backend fields at %s", 1882 info->xbdev->otherend); 1883 return; 1884 } 1885 1886 /* 1887 * physcial-sector-size is a newer field, so old backends may not 1888 * provide this. Assume physical sector size to be the same as 1889 * sector_size in that case. 1890 */ 1891 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1892 "physical-sector-size", "%u", &physical_sector_size); 1893 if (err != 1) 1894 physical_sector_size = sector_size; 1895 1896 err = blkfront_gather_backend_features(info); 1897 if (err) { 1898 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 1899 info->xbdev->otherend); 1900 return; 1901 } 1902 1903 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 1904 physical_sector_size); 1905 if (err) { 1906 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 1907 info->xbdev->otherend); 1908 return; 1909 } 1910 1911 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1912 1913 /* Kick pending requests. */ 1914 spin_lock_irq(&info->io_lock); 1915 info->connected = BLKIF_STATE_CONNECTED; 1916 kick_pending_request_queues(info); 1917 spin_unlock_irq(&info->io_lock); 1918 1919 add_disk(info->gd); 1920 1921 info->is_ready = 1; 1922 } 1923 1924 /** 1925 * Callback received when the backend's state changes. 1926 */ 1927 static void blkback_changed(struct xenbus_device *dev, 1928 enum xenbus_state backend_state) 1929 { 1930 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1931 1932 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 1933 1934 switch (backend_state) { 1935 case XenbusStateInitWait: 1936 if (dev->state != XenbusStateInitialising) 1937 break; 1938 if (talk_to_blkback(dev, info)) { 1939 kfree(info); 1940 dev_set_drvdata(&dev->dev, NULL); 1941 break; 1942 } 1943 case XenbusStateInitialising: 1944 case XenbusStateInitialised: 1945 case XenbusStateReconfiguring: 1946 case XenbusStateReconfigured: 1947 case XenbusStateUnknown: 1948 break; 1949 1950 case XenbusStateConnected: 1951 blkfront_connect(info); 1952 break; 1953 1954 case XenbusStateClosed: 1955 if (dev->state == XenbusStateClosed) 1956 break; 1957 /* Missed the backend's Closing state -- fallthrough */ 1958 case XenbusStateClosing: 1959 if (info) 1960 blkfront_closing(info); 1961 break; 1962 } 1963 } 1964 1965 static int blkfront_remove(struct xenbus_device *xbdev) 1966 { 1967 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 1968 struct block_device *bdev = NULL; 1969 struct gendisk *disk; 1970 1971 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 1972 1973 blkif_free(info, 0); 1974 1975 mutex_lock(&info->mutex); 1976 1977 disk = info->gd; 1978 if (disk) 1979 bdev = bdget_disk(disk, 0); 1980 1981 info->xbdev = NULL; 1982 mutex_unlock(&info->mutex); 1983 1984 if (!bdev) { 1985 kfree(info); 1986 return 0; 1987 } 1988 1989 /* 1990 * The xbdev was removed before we reached the Closed 1991 * state. See if it's safe to remove the disk. If the bdev 1992 * isn't closed yet, we let release take care of it. 1993 */ 1994 1995 mutex_lock(&bdev->bd_mutex); 1996 info = disk->private_data; 1997 1998 dev_warn(disk_to_dev(disk), 1999 "%s was hot-unplugged, %d stale handles\n", 2000 xbdev->nodename, bdev->bd_openers); 2001 2002 if (info && !bdev->bd_openers) { 2003 xlvbd_release_gendisk(info); 2004 disk->private_data = NULL; 2005 kfree(info); 2006 } 2007 2008 mutex_unlock(&bdev->bd_mutex); 2009 bdput(bdev); 2010 2011 return 0; 2012 } 2013 2014 static int blkfront_is_ready(struct xenbus_device *dev) 2015 { 2016 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2017 2018 return info->is_ready && info->xbdev; 2019 } 2020 2021 static int blkif_open(struct block_device *bdev, fmode_t mode) 2022 { 2023 struct gendisk *disk = bdev->bd_disk; 2024 struct blkfront_info *info; 2025 int err = 0; 2026 2027 mutex_lock(&blkfront_mutex); 2028 2029 info = disk->private_data; 2030 if (!info) { 2031 /* xbdev gone */ 2032 err = -ERESTARTSYS; 2033 goto out; 2034 } 2035 2036 mutex_lock(&info->mutex); 2037 2038 if (!info->gd) 2039 /* xbdev is closed */ 2040 err = -ERESTARTSYS; 2041 2042 mutex_unlock(&info->mutex); 2043 2044 out: 2045 mutex_unlock(&blkfront_mutex); 2046 return err; 2047 } 2048 2049 static void blkif_release(struct gendisk *disk, fmode_t mode) 2050 { 2051 struct blkfront_info *info = disk->private_data; 2052 struct block_device *bdev; 2053 struct xenbus_device *xbdev; 2054 2055 mutex_lock(&blkfront_mutex); 2056 2057 bdev = bdget_disk(disk, 0); 2058 2059 if (!bdev) { 2060 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2061 goto out_mutex; 2062 } 2063 if (bdev->bd_openers) 2064 goto out; 2065 2066 /* 2067 * Check if we have been instructed to close. We will have 2068 * deferred this request, because the bdev was still open. 2069 */ 2070 2071 mutex_lock(&info->mutex); 2072 xbdev = info->xbdev; 2073 2074 if (xbdev && xbdev->state == XenbusStateClosing) { 2075 /* pending switch to state closed */ 2076 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2077 xlvbd_release_gendisk(info); 2078 xenbus_frontend_closed(info->xbdev); 2079 } 2080 2081 mutex_unlock(&info->mutex); 2082 2083 if (!xbdev) { 2084 /* sudden device removal */ 2085 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2086 xlvbd_release_gendisk(info); 2087 disk->private_data = NULL; 2088 kfree(info); 2089 } 2090 2091 out: 2092 bdput(bdev); 2093 out_mutex: 2094 mutex_unlock(&blkfront_mutex); 2095 } 2096 2097 static const struct block_device_operations xlvbd_block_fops = 2098 { 2099 .owner = THIS_MODULE, 2100 .open = blkif_open, 2101 .release = blkif_release, 2102 .getgeo = blkif_getgeo, 2103 .ioctl = blkif_ioctl, 2104 }; 2105 2106 2107 static const struct xenbus_device_id blkfront_ids[] = { 2108 { "vbd" }, 2109 { "" } 2110 }; 2111 2112 static struct xenbus_driver blkfront_driver = { 2113 .ids = blkfront_ids, 2114 .probe = blkfront_probe, 2115 .remove = blkfront_remove, 2116 .resume = blkfront_resume, 2117 .otherend_changed = blkback_changed, 2118 .is_ready = blkfront_is_ready, 2119 }; 2120 2121 static int __init xlblk_init(void) 2122 { 2123 int ret; 2124 2125 if (!xen_domain()) 2126 return -ENODEV; 2127 2128 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_PAGE_ORDER) { 2129 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 2130 xen_blkif_max_ring_order, XENBUS_MAX_RING_PAGE_ORDER); 2131 xen_blkif_max_ring_order = 0; 2132 } 2133 2134 if (!xen_has_pv_disk_devices()) 2135 return -ENODEV; 2136 2137 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2138 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2139 XENVBD_MAJOR, DEV_NAME); 2140 return -ENODEV; 2141 } 2142 2143 ret = xenbus_register_frontend(&blkfront_driver); 2144 if (ret) { 2145 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2146 return ret; 2147 } 2148 2149 return 0; 2150 } 2151 module_init(xlblk_init); 2152 2153 2154 static void __exit xlblk_exit(void) 2155 { 2156 xenbus_unregister_driver(&blkfront_driver); 2157 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2158 kfree(minors); 2159 } 2160 module_exit(xlblk_exit); 2161 2162 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2163 MODULE_LICENSE("GPL"); 2164 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2165 MODULE_ALIAS("xen:vbd"); 2166 MODULE_ALIAS("xenblk"); 2167