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 /* 64 * The minimal size of segment supported by the block framework is PAGE_SIZE. 65 * When Linux is using a different page size than Xen, it may not be possible 66 * to put all the data in a single segment. 67 * This can happen when the backend doesn't support indirect descriptor and 68 * therefore the maximum amount of data that a request can carry is 69 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB 70 * 71 * Note that we only support one extra request. So the Linux page size 72 * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) = 73 * 88KB. 74 */ 75 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE) 76 77 enum blkif_state { 78 BLKIF_STATE_DISCONNECTED, 79 BLKIF_STATE_CONNECTED, 80 BLKIF_STATE_SUSPENDED, 81 }; 82 83 struct grant { 84 grant_ref_t gref; 85 struct page *page; 86 struct list_head node; 87 }; 88 89 enum blk_req_status { 90 REQ_WAITING, 91 REQ_DONE, 92 REQ_ERROR, 93 REQ_EOPNOTSUPP, 94 }; 95 96 struct blk_shadow { 97 struct blkif_request req; 98 struct request *request; 99 struct grant **grants_used; 100 struct grant **indirect_grants; 101 struct scatterlist *sg; 102 unsigned int num_sg; 103 enum blk_req_status status; 104 105 #define NO_ASSOCIATED_ID ~0UL 106 /* 107 * Id of the sibling if we ever need 2 requests when handling a 108 * block I/O request 109 */ 110 unsigned long associated_id; 111 }; 112 113 struct blkif_req { 114 int error; 115 }; 116 117 static inline struct blkif_req *blkif_req(struct request *rq) 118 { 119 return blk_mq_rq_to_pdu(rq); 120 } 121 122 static DEFINE_MUTEX(blkfront_mutex); 123 static const struct block_device_operations xlvbd_block_fops; 124 125 /* 126 * Maximum number of segments in indirect requests, the actual value used by 127 * the frontend driver is the minimum of this value and the value provided 128 * by the backend driver. 129 */ 130 131 static unsigned int xen_blkif_max_segments = 32; 132 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 133 S_IRUGO); 134 MODULE_PARM_DESC(max_indirect_segments, 135 "Maximum amount of segments in indirect requests (default is 32)"); 136 137 static unsigned int xen_blkif_max_queues = 4; 138 module_param_named(max_queues, xen_blkif_max_queues, uint, S_IRUGO); 139 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk"); 140 141 /* 142 * Maximum order of pages to be used for the shared ring between front and 143 * backend, 4KB page granularity is used. 144 */ 145 static unsigned int xen_blkif_max_ring_order; 146 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO); 147 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 148 149 #define BLK_RING_SIZE(info) \ 150 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages) 151 152 #define BLK_MAX_RING_SIZE \ 153 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS) 154 155 /* 156 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 157 * characters are enough. Define to 20 to keep consistent with backend. 158 */ 159 #define RINGREF_NAME_LEN (20) 160 /* 161 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters. 162 */ 163 #define QUEUE_NAME_LEN (17) 164 165 /* 166 * Per-ring info. 167 * Every blkfront device can associate with one or more blkfront_ring_info, 168 * depending on how many hardware queues/rings to be used. 169 */ 170 struct blkfront_ring_info { 171 /* Lock to protect data in every ring buffer. */ 172 spinlock_t ring_lock; 173 struct blkif_front_ring ring; 174 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS]; 175 unsigned int evtchn, irq; 176 struct work_struct work; 177 struct gnttab_free_callback callback; 178 struct blk_shadow shadow[BLK_MAX_RING_SIZE]; 179 struct list_head indirect_pages; 180 struct list_head grants; 181 unsigned int persistent_gnts_c; 182 unsigned long shadow_free; 183 struct blkfront_info *dev_info; 184 }; 185 186 /* 187 * We have one of these per vbd, whether ide, scsi or 'other'. They 188 * hang in private_data off the gendisk structure. We may end up 189 * putting all kinds of interesting stuff here :-) 190 */ 191 struct blkfront_info 192 { 193 struct mutex mutex; 194 struct xenbus_device *xbdev; 195 struct gendisk *gd; 196 u16 sector_size; 197 unsigned int physical_sector_size; 198 int vdevice; 199 blkif_vdev_t handle; 200 enum blkif_state connected; 201 /* Number of pages per ring buffer. */ 202 unsigned int nr_ring_pages; 203 struct request_queue *rq; 204 unsigned int feature_flush:1; 205 unsigned int feature_fua:1; 206 unsigned int feature_discard:1; 207 unsigned int feature_secdiscard:1; 208 unsigned int feature_persistent:1; 209 unsigned int discard_granularity; 210 unsigned int discard_alignment; 211 /* Number of 4KB segments handled */ 212 unsigned int max_indirect_segments; 213 int is_ready; 214 struct blk_mq_tag_set tag_set; 215 struct blkfront_ring_info *rinfo; 216 unsigned int nr_rings; 217 /* Save uncomplete reqs and bios for migration. */ 218 struct list_head requests; 219 struct bio_list bio_list; 220 }; 221 222 static unsigned int nr_minors; 223 static unsigned long *minors; 224 static DEFINE_SPINLOCK(minor_lock); 225 226 #define GRANT_INVALID_REF 0 227 228 #define PARTS_PER_DISK 16 229 #define PARTS_PER_EXT_DISK 256 230 231 #define BLKIF_MAJOR(dev) ((dev)>>8) 232 #define BLKIF_MINOR(dev) ((dev) & 0xff) 233 234 #define EXT_SHIFT 28 235 #define EXTENDED (1<<EXT_SHIFT) 236 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 237 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 238 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 239 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 240 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 241 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 242 243 #define DEV_NAME "xvd" /* name in /dev */ 244 245 /* 246 * Grants are always the same size as a Xen page (i.e 4KB). 247 * A physical segment is always the same size as a Linux page. 248 * Number of grants per physical segment 249 */ 250 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE) 251 252 #define GRANTS_PER_INDIRECT_FRAME \ 253 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment)) 254 255 #define PSEGS_PER_INDIRECT_FRAME \ 256 (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS) 257 258 #define INDIRECT_GREFS(_grants) \ 259 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME) 260 261 #define GREFS(_psegs) ((_psegs) * GRANTS_PER_PSEG) 262 263 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo); 264 static void blkfront_gather_backend_features(struct blkfront_info *info); 265 266 static int get_id_from_freelist(struct blkfront_ring_info *rinfo) 267 { 268 unsigned long free = rinfo->shadow_free; 269 270 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info)); 271 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id; 272 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 273 return free; 274 } 275 276 static int add_id_to_freelist(struct blkfront_ring_info *rinfo, 277 unsigned long id) 278 { 279 if (rinfo->shadow[id].req.u.rw.id != id) 280 return -EINVAL; 281 if (rinfo->shadow[id].request == NULL) 282 return -EINVAL; 283 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free; 284 rinfo->shadow[id].request = NULL; 285 rinfo->shadow_free = id; 286 return 0; 287 } 288 289 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 290 { 291 struct blkfront_info *info = rinfo->dev_info; 292 struct page *granted_page; 293 struct grant *gnt_list_entry, *n; 294 int i = 0; 295 296 while (i < num) { 297 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 298 if (!gnt_list_entry) 299 goto out_of_memory; 300 301 if (info->feature_persistent) { 302 granted_page = alloc_page(GFP_NOIO); 303 if (!granted_page) { 304 kfree(gnt_list_entry); 305 goto out_of_memory; 306 } 307 gnt_list_entry->page = granted_page; 308 } 309 310 gnt_list_entry->gref = GRANT_INVALID_REF; 311 list_add(&gnt_list_entry->node, &rinfo->grants); 312 i++; 313 } 314 315 return 0; 316 317 out_of_memory: 318 list_for_each_entry_safe(gnt_list_entry, n, 319 &rinfo->grants, node) { 320 list_del(&gnt_list_entry->node); 321 if (info->feature_persistent) 322 __free_page(gnt_list_entry->page); 323 kfree(gnt_list_entry); 324 i--; 325 } 326 BUG_ON(i != 0); 327 return -ENOMEM; 328 } 329 330 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo) 331 { 332 struct grant *gnt_list_entry; 333 334 BUG_ON(list_empty(&rinfo->grants)); 335 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant, 336 node); 337 list_del(&gnt_list_entry->node); 338 339 if (gnt_list_entry->gref != GRANT_INVALID_REF) 340 rinfo->persistent_gnts_c--; 341 342 return gnt_list_entry; 343 } 344 345 static inline void grant_foreign_access(const struct grant *gnt_list_entry, 346 const struct blkfront_info *info) 347 { 348 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref, 349 info->xbdev->otherend_id, 350 gnt_list_entry->page, 351 0); 352 } 353 354 static struct grant *get_grant(grant_ref_t *gref_head, 355 unsigned long gfn, 356 struct blkfront_ring_info *rinfo) 357 { 358 struct grant *gnt_list_entry = get_free_grant(rinfo); 359 struct blkfront_info *info = rinfo->dev_info; 360 361 if (gnt_list_entry->gref != GRANT_INVALID_REF) 362 return gnt_list_entry; 363 364 /* Assign a gref to this page */ 365 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 366 BUG_ON(gnt_list_entry->gref == -ENOSPC); 367 if (info->feature_persistent) 368 grant_foreign_access(gnt_list_entry, info); 369 else { 370 /* Grant access to the GFN passed by the caller */ 371 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 372 info->xbdev->otherend_id, 373 gfn, 0); 374 } 375 376 return gnt_list_entry; 377 } 378 379 static struct grant *get_indirect_grant(grant_ref_t *gref_head, 380 struct blkfront_ring_info *rinfo) 381 { 382 struct grant *gnt_list_entry = get_free_grant(rinfo); 383 struct blkfront_info *info = rinfo->dev_info; 384 385 if (gnt_list_entry->gref != GRANT_INVALID_REF) 386 return gnt_list_entry; 387 388 /* Assign a gref to this page */ 389 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 390 BUG_ON(gnt_list_entry->gref == -ENOSPC); 391 if (!info->feature_persistent) { 392 struct page *indirect_page; 393 394 /* Fetch a pre-allocated page to use for indirect grefs */ 395 BUG_ON(list_empty(&rinfo->indirect_pages)); 396 indirect_page = list_first_entry(&rinfo->indirect_pages, 397 struct page, lru); 398 list_del(&indirect_page->lru); 399 gnt_list_entry->page = indirect_page; 400 } 401 grant_foreign_access(gnt_list_entry, info); 402 403 return gnt_list_entry; 404 } 405 406 static const char *op_name(int op) 407 { 408 static const char *const names[] = { 409 [BLKIF_OP_READ] = "read", 410 [BLKIF_OP_WRITE] = "write", 411 [BLKIF_OP_WRITE_BARRIER] = "barrier", 412 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 413 [BLKIF_OP_DISCARD] = "discard" }; 414 415 if (op < 0 || op >= ARRAY_SIZE(names)) 416 return "unknown"; 417 418 if (!names[op]) 419 return "reserved"; 420 421 return names[op]; 422 } 423 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 424 { 425 unsigned int end = minor + nr; 426 int rc; 427 428 if (end > nr_minors) { 429 unsigned long *bitmap, *old; 430 431 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 432 GFP_KERNEL); 433 if (bitmap == NULL) 434 return -ENOMEM; 435 436 spin_lock(&minor_lock); 437 if (end > nr_minors) { 438 old = minors; 439 memcpy(bitmap, minors, 440 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 441 minors = bitmap; 442 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 443 } else 444 old = bitmap; 445 spin_unlock(&minor_lock); 446 kfree(old); 447 } 448 449 spin_lock(&minor_lock); 450 if (find_next_bit(minors, end, minor) >= end) { 451 bitmap_set(minors, minor, nr); 452 rc = 0; 453 } else 454 rc = -EBUSY; 455 spin_unlock(&minor_lock); 456 457 return rc; 458 } 459 460 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 461 { 462 unsigned int end = minor + nr; 463 464 BUG_ON(end > nr_minors); 465 spin_lock(&minor_lock); 466 bitmap_clear(minors, minor, nr); 467 spin_unlock(&minor_lock); 468 } 469 470 static void blkif_restart_queue_callback(void *arg) 471 { 472 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg; 473 schedule_work(&rinfo->work); 474 } 475 476 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 477 { 478 /* We don't have real geometry info, but let's at least return 479 values consistent with the size of the device */ 480 sector_t nsect = get_capacity(bd->bd_disk); 481 sector_t cylinders = nsect; 482 483 hg->heads = 0xff; 484 hg->sectors = 0x3f; 485 sector_div(cylinders, hg->heads * hg->sectors); 486 hg->cylinders = cylinders; 487 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 488 hg->cylinders = 0xffff; 489 return 0; 490 } 491 492 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 493 unsigned command, unsigned long argument) 494 { 495 struct blkfront_info *info = bdev->bd_disk->private_data; 496 int i; 497 498 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 499 command, (long)argument); 500 501 switch (command) { 502 case CDROMMULTISESSION: 503 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 504 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 505 if (put_user(0, (char __user *)(argument + i))) 506 return -EFAULT; 507 return 0; 508 509 case CDROM_GET_CAPABILITY: { 510 struct gendisk *gd = info->gd; 511 if (gd->flags & GENHD_FL_CD) 512 return 0; 513 return -EINVAL; 514 } 515 516 default: 517 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 518 command);*/ 519 return -EINVAL; /* same return as native Linux */ 520 } 521 522 return 0; 523 } 524 525 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, 526 struct request *req, 527 struct blkif_request **ring_req) 528 { 529 unsigned long id; 530 531 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt); 532 rinfo->ring.req_prod_pvt++; 533 534 id = get_id_from_freelist(rinfo); 535 rinfo->shadow[id].request = req; 536 rinfo->shadow[id].status = REQ_WAITING; 537 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID; 538 539 (*ring_req)->u.rw.id = id; 540 541 return id; 542 } 543 544 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo) 545 { 546 struct blkfront_info *info = rinfo->dev_info; 547 struct blkif_request *ring_req; 548 unsigned long id; 549 550 /* Fill out a communications ring structure. */ 551 id = blkif_ring_get_request(rinfo, req, &ring_req); 552 553 ring_req->operation = BLKIF_OP_DISCARD; 554 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 555 ring_req->u.discard.id = id; 556 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 557 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard) 558 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 559 else 560 ring_req->u.discard.flag = 0; 561 562 /* Keep a private copy so we can reissue requests when recovering. */ 563 rinfo->shadow[id].req = *ring_req; 564 565 return 0; 566 } 567 568 struct setup_rw_req { 569 unsigned int grant_idx; 570 struct blkif_request_segment *segments; 571 struct blkfront_ring_info *rinfo; 572 struct blkif_request *ring_req; 573 grant_ref_t gref_head; 574 unsigned int id; 575 /* Only used when persistent grant is used and it's a read request */ 576 bool need_copy; 577 unsigned int bvec_off; 578 char *bvec_data; 579 580 bool require_extra_req; 581 struct blkif_request *extra_ring_req; 582 }; 583 584 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset, 585 unsigned int len, void *data) 586 { 587 struct setup_rw_req *setup = data; 588 int n, ref; 589 struct grant *gnt_list_entry; 590 unsigned int fsect, lsect; 591 /* Convenient aliases */ 592 unsigned int grant_idx = setup->grant_idx; 593 struct blkif_request *ring_req = setup->ring_req; 594 struct blkfront_ring_info *rinfo = setup->rinfo; 595 /* 596 * We always use the shadow of the first request to store the list 597 * of grant associated to the block I/O request. This made the 598 * completion more easy to handle even if the block I/O request is 599 * split. 600 */ 601 struct blk_shadow *shadow = &rinfo->shadow[setup->id]; 602 603 if (unlikely(setup->require_extra_req && 604 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 605 /* 606 * We are using the second request, setup grant_idx 607 * to be the index of the segment array. 608 */ 609 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST; 610 ring_req = setup->extra_ring_req; 611 } 612 613 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 614 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) { 615 if (setup->segments) 616 kunmap_atomic(setup->segments); 617 618 n = grant_idx / GRANTS_PER_INDIRECT_FRAME; 619 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo); 620 shadow->indirect_grants[n] = gnt_list_entry; 621 setup->segments = kmap_atomic(gnt_list_entry->page); 622 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 623 } 624 625 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo); 626 ref = gnt_list_entry->gref; 627 /* 628 * All the grants are stored in the shadow of the first 629 * request. Therefore we have to use the global index. 630 */ 631 shadow->grants_used[setup->grant_idx] = gnt_list_entry; 632 633 if (setup->need_copy) { 634 void *shared_data; 635 636 shared_data = kmap_atomic(gnt_list_entry->page); 637 /* 638 * this does not wipe data stored outside the 639 * range sg->offset..sg->offset+sg->length. 640 * Therefore, blkback *could* see data from 641 * previous requests. This is OK as long as 642 * persistent grants are shared with just one 643 * domain. It may need refactoring if this 644 * changes 645 */ 646 memcpy(shared_data + offset, 647 setup->bvec_data + setup->bvec_off, 648 len); 649 650 kunmap_atomic(shared_data); 651 setup->bvec_off += len; 652 } 653 654 fsect = offset >> 9; 655 lsect = fsect + (len >> 9) - 1; 656 if (ring_req->operation != BLKIF_OP_INDIRECT) { 657 ring_req->u.rw.seg[grant_idx] = 658 (struct blkif_request_segment) { 659 .gref = ref, 660 .first_sect = fsect, 661 .last_sect = lsect }; 662 } else { 663 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] = 664 (struct blkif_request_segment) { 665 .gref = ref, 666 .first_sect = fsect, 667 .last_sect = lsect }; 668 } 669 670 (setup->grant_idx)++; 671 } 672 673 static void blkif_setup_extra_req(struct blkif_request *first, 674 struct blkif_request *second) 675 { 676 uint16_t nr_segments = first->u.rw.nr_segments; 677 678 /* 679 * The second request is only present when the first request uses 680 * all its segments. It's always the continuity of the first one. 681 */ 682 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 683 684 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST; 685 second->u.rw.sector_number = first->u.rw.sector_number + 686 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512; 687 688 second->u.rw.handle = first->u.rw.handle; 689 second->operation = first->operation; 690 } 691 692 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo) 693 { 694 struct blkfront_info *info = rinfo->dev_info; 695 struct blkif_request *ring_req, *extra_ring_req = NULL; 696 unsigned long id, extra_id = NO_ASSOCIATED_ID; 697 bool require_extra_req = false; 698 int i; 699 struct setup_rw_req setup = { 700 .grant_idx = 0, 701 .segments = NULL, 702 .rinfo = rinfo, 703 .need_copy = rq_data_dir(req) && info->feature_persistent, 704 }; 705 706 /* 707 * Used to store if we are able to queue the request by just using 708 * existing persistent grants, or if we have to get new grants, 709 * as there are not sufficiently many free. 710 */ 711 struct scatterlist *sg; 712 int num_sg, max_grefs, num_grant; 713 714 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG; 715 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 716 /* 717 * If we are using indirect segments we need to account 718 * for the indirect grefs used in the request. 719 */ 720 max_grefs += INDIRECT_GREFS(max_grefs); 721 722 /* 723 * We have to reserve 'max_grefs' grants because persistent 724 * grants are shared by all rings. 725 */ 726 if (max_grefs > 0) 727 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) { 728 gnttab_request_free_callback( 729 &rinfo->callback, 730 blkif_restart_queue_callback, 731 rinfo, 732 max_grefs); 733 return 1; 734 } 735 736 /* Fill out a communications ring structure. */ 737 id = blkif_ring_get_request(rinfo, req, &ring_req); 738 739 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg); 740 num_grant = 0; 741 /* Calculate the number of grant used */ 742 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) 743 num_grant += gnttab_count_grant(sg->offset, sg->length); 744 745 require_extra_req = info->max_indirect_segments == 0 && 746 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST; 747 BUG_ON(!HAS_EXTRA_REQ && require_extra_req); 748 749 rinfo->shadow[id].num_sg = num_sg; 750 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST && 751 likely(!require_extra_req)) { 752 /* 753 * The indirect operation can only be a BLKIF_OP_READ or 754 * BLKIF_OP_WRITE 755 */ 756 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA); 757 ring_req->operation = BLKIF_OP_INDIRECT; 758 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 759 BLKIF_OP_WRITE : BLKIF_OP_READ; 760 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 761 ring_req->u.indirect.handle = info->handle; 762 ring_req->u.indirect.nr_segments = num_grant; 763 } else { 764 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 765 ring_req->u.rw.handle = info->handle; 766 ring_req->operation = rq_data_dir(req) ? 767 BLKIF_OP_WRITE : BLKIF_OP_READ; 768 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) { 769 /* 770 * Ideally we can do an unordered flush-to-disk. 771 * In case the backend onlysupports barriers, use that. 772 * A barrier request a superset of FUA, so we can 773 * implement it the same way. (It's also a FLUSH+FUA, 774 * since it is guaranteed ordered WRT previous writes.) 775 */ 776 if (info->feature_flush && info->feature_fua) 777 ring_req->operation = 778 BLKIF_OP_WRITE_BARRIER; 779 else if (info->feature_flush) 780 ring_req->operation = 781 BLKIF_OP_FLUSH_DISKCACHE; 782 else 783 ring_req->operation = 0; 784 } 785 ring_req->u.rw.nr_segments = num_grant; 786 if (unlikely(require_extra_req)) { 787 extra_id = blkif_ring_get_request(rinfo, req, 788 &extra_ring_req); 789 /* 790 * Only the first request contains the scatter-gather 791 * list. 792 */ 793 rinfo->shadow[extra_id].num_sg = 0; 794 795 blkif_setup_extra_req(ring_req, extra_ring_req); 796 797 /* Link the 2 requests together */ 798 rinfo->shadow[extra_id].associated_id = id; 799 rinfo->shadow[id].associated_id = extra_id; 800 } 801 } 802 803 setup.ring_req = ring_req; 804 setup.id = id; 805 806 setup.require_extra_req = require_extra_req; 807 if (unlikely(require_extra_req)) 808 setup.extra_ring_req = extra_ring_req; 809 810 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) { 811 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 812 813 if (setup.need_copy) { 814 setup.bvec_off = sg->offset; 815 setup.bvec_data = kmap_atomic(sg_page(sg)); 816 } 817 818 gnttab_foreach_grant_in_range(sg_page(sg), 819 sg->offset, 820 sg->length, 821 blkif_setup_rw_req_grant, 822 &setup); 823 824 if (setup.need_copy) 825 kunmap_atomic(setup.bvec_data); 826 } 827 if (setup.segments) 828 kunmap_atomic(setup.segments); 829 830 /* Keep a private copy so we can reissue requests when recovering. */ 831 rinfo->shadow[id].req = *ring_req; 832 if (unlikely(require_extra_req)) 833 rinfo->shadow[extra_id].req = *extra_ring_req; 834 835 if (max_grefs > 0) 836 gnttab_free_grant_references(setup.gref_head); 837 838 return 0; 839 } 840 841 /* 842 * Generate a Xen blkfront IO request from a blk layer request. Reads 843 * and writes are handled as expected. 844 * 845 * @req: a request struct 846 */ 847 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo) 848 { 849 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED)) 850 return 1; 851 852 if (unlikely(req_op(req) == REQ_OP_DISCARD || 853 req_op(req) == REQ_OP_SECURE_ERASE)) 854 return blkif_queue_discard_req(req, rinfo); 855 else 856 return blkif_queue_rw_req(req, rinfo); 857 } 858 859 static inline void flush_requests(struct blkfront_ring_info *rinfo) 860 { 861 int notify; 862 863 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify); 864 865 if (notify) 866 notify_remote_via_irq(rinfo->irq); 867 } 868 869 static inline bool blkif_request_flush_invalid(struct request *req, 870 struct blkfront_info *info) 871 { 872 return (blk_rq_is_passthrough(req) || 873 ((req_op(req) == REQ_OP_FLUSH) && 874 !info->feature_flush) || 875 ((req->cmd_flags & REQ_FUA) && 876 !info->feature_fua)); 877 } 878 879 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx, 880 const struct blk_mq_queue_data *qd) 881 { 882 unsigned long flags; 883 int qid = hctx->queue_num; 884 struct blkfront_info *info = hctx->queue->queuedata; 885 struct blkfront_ring_info *rinfo = NULL; 886 887 BUG_ON(info->nr_rings <= qid); 888 rinfo = &info->rinfo[qid]; 889 blk_mq_start_request(qd->rq); 890 spin_lock_irqsave(&rinfo->ring_lock, flags); 891 if (RING_FULL(&rinfo->ring)) 892 goto out_busy; 893 894 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info)) 895 goto out_err; 896 897 if (blkif_queue_request(qd->rq, rinfo)) 898 goto out_busy; 899 900 flush_requests(rinfo); 901 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 902 return BLK_STS_OK; 903 904 out_err: 905 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 906 return BLK_STS_IOERR; 907 908 out_busy: 909 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 910 blk_mq_stop_hw_queue(hctx); 911 return BLK_STS_RESOURCE; 912 } 913 914 static void blkif_complete_rq(struct request *rq) 915 { 916 blk_mq_end_request(rq, blkif_req(rq)->error); 917 } 918 919 static const struct blk_mq_ops blkfront_mq_ops = { 920 .queue_rq = blkif_queue_rq, 921 .complete = blkif_complete_rq, 922 }; 923 924 static void blkif_set_queue_limits(struct blkfront_info *info) 925 { 926 struct request_queue *rq = info->rq; 927 struct gendisk *gd = info->gd; 928 unsigned int segments = info->max_indirect_segments ? : 929 BLKIF_MAX_SEGMENTS_PER_REQUEST; 930 931 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 932 933 if (info->feature_discard) { 934 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); 935 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 936 rq->limits.discard_granularity = info->discard_granularity; 937 rq->limits.discard_alignment = info->discard_alignment; 938 if (info->feature_secdiscard) 939 queue_flag_set_unlocked(QUEUE_FLAG_SECERASE, rq); 940 } 941 942 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 943 blk_queue_logical_block_size(rq, info->sector_size); 944 blk_queue_physical_block_size(rq, info->physical_sector_size); 945 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512); 946 947 /* Each segment in a request is up to an aligned page in size. */ 948 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 949 blk_queue_max_segment_size(rq, PAGE_SIZE); 950 951 /* Ensure a merged request will fit in a single I/O ring slot. */ 952 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG); 953 954 /* Make sure buffer addresses are sector-aligned. */ 955 blk_queue_dma_alignment(rq, 511); 956 } 957 958 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, 959 unsigned int physical_sector_size) 960 { 961 struct request_queue *rq; 962 struct blkfront_info *info = gd->private_data; 963 964 memset(&info->tag_set, 0, sizeof(info->tag_set)); 965 info->tag_set.ops = &blkfront_mq_ops; 966 info->tag_set.nr_hw_queues = info->nr_rings; 967 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) { 968 /* 969 * When indirect descriptior is not supported, the I/O request 970 * will be split between multiple request in the ring. 971 * To avoid problems when sending the request, divide by 972 * 2 the depth of the queue. 973 */ 974 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2; 975 } else 976 info->tag_set.queue_depth = BLK_RING_SIZE(info); 977 info->tag_set.numa_node = NUMA_NO_NODE; 978 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; 979 info->tag_set.cmd_size = sizeof(struct blkif_req); 980 info->tag_set.driver_data = info; 981 982 if (blk_mq_alloc_tag_set(&info->tag_set)) 983 return -EINVAL; 984 rq = blk_mq_init_queue(&info->tag_set); 985 if (IS_ERR(rq)) { 986 blk_mq_free_tag_set(&info->tag_set); 987 return PTR_ERR(rq); 988 } 989 990 rq->queuedata = info; 991 info->rq = gd->queue = rq; 992 info->gd = gd; 993 info->sector_size = sector_size; 994 info->physical_sector_size = physical_sector_size; 995 blkif_set_queue_limits(info); 996 997 return 0; 998 } 999 1000 static const char *flush_info(struct blkfront_info *info) 1001 { 1002 if (info->feature_flush && info->feature_fua) 1003 return "barrier: enabled;"; 1004 else if (info->feature_flush) 1005 return "flush diskcache: enabled;"; 1006 else 1007 return "barrier or flush: disabled;"; 1008 } 1009 1010 static void xlvbd_flush(struct blkfront_info *info) 1011 { 1012 blk_queue_write_cache(info->rq, info->feature_flush ? true : false, 1013 info->feature_fua ? true : false); 1014 pr_info("blkfront: %s: %s %s %s %s %s\n", 1015 info->gd->disk_name, flush_info(info), 1016 "persistent grants:", info->feature_persistent ? 1017 "enabled;" : "disabled;", "indirect descriptors:", 1018 info->max_indirect_segments ? "enabled;" : "disabled;"); 1019 } 1020 1021 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 1022 { 1023 int major; 1024 major = BLKIF_MAJOR(vdevice); 1025 *minor = BLKIF_MINOR(vdevice); 1026 switch (major) { 1027 case XEN_IDE0_MAJOR: 1028 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 1029 *minor = ((*minor / 64) * PARTS_PER_DISK) + 1030 EMULATED_HD_DISK_MINOR_OFFSET; 1031 break; 1032 case XEN_IDE1_MAJOR: 1033 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 1034 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 1035 EMULATED_HD_DISK_MINOR_OFFSET; 1036 break; 1037 case XEN_SCSI_DISK0_MAJOR: 1038 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 1039 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 1040 break; 1041 case XEN_SCSI_DISK1_MAJOR: 1042 case XEN_SCSI_DISK2_MAJOR: 1043 case XEN_SCSI_DISK3_MAJOR: 1044 case XEN_SCSI_DISK4_MAJOR: 1045 case XEN_SCSI_DISK5_MAJOR: 1046 case XEN_SCSI_DISK6_MAJOR: 1047 case XEN_SCSI_DISK7_MAJOR: 1048 *offset = (*minor / PARTS_PER_DISK) + 1049 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 1050 EMULATED_SD_DISK_NAME_OFFSET; 1051 *minor = *minor + 1052 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 1053 EMULATED_SD_DISK_MINOR_OFFSET; 1054 break; 1055 case XEN_SCSI_DISK8_MAJOR: 1056 case XEN_SCSI_DISK9_MAJOR: 1057 case XEN_SCSI_DISK10_MAJOR: 1058 case XEN_SCSI_DISK11_MAJOR: 1059 case XEN_SCSI_DISK12_MAJOR: 1060 case XEN_SCSI_DISK13_MAJOR: 1061 case XEN_SCSI_DISK14_MAJOR: 1062 case XEN_SCSI_DISK15_MAJOR: 1063 *offset = (*minor / PARTS_PER_DISK) + 1064 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 1065 EMULATED_SD_DISK_NAME_OFFSET; 1066 *minor = *minor + 1067 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 1068 EMULATED_SD_DISK_MINOR_OFFSET; 1069 break; 1070 case XENVBD_MAJOR: 1071 *offset = *minor / PARTS_PER_DISK; 1072 break; 1073 default: 1074 printk(KERN_WARNING "blkfront: your disk configuration is " 1075 "incorrect, please use an xvd device instead\n"); 1076 return -ENODEV; 1077 } 1078 return 0; 1079 } 1080 1081 static char *encode_disk_name(char *ptr, unsigned int n) 1082 { 1083 if (n >= 26) 1084 ptr = encode_disk_name(ptr, n / 26 - 1); 1085 *ptr = 'a' + n % 26; 1086 return ptr + 1; 1087 } 1088 1089 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 1090 struct blkfront_info *info, 1091 u16 vdisk_info, u16 sector_size, 1092 unsigned int physical_sector_size) 1093 { 1094 struct gendisk *gd; 1095 int nr_minors = 1; 1096 int err; 1097 unsigned int offset; 1098 int minor; 1099 int nr_parts; 1100 char *ptr; 1101 1102 BUG_ON(info->gd != NULL); 1103 BUG_ON(info->rq != NULL); 1104 1105 if ((info->vdevice>>EXT_SHIFT) > 1) { 1106 /* this is above the extended range; something is wrong */ 1107 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 1108 return -ENODEV; 1109 } 1110 1111 if (!VDEV_IS_EXTENDED(info->vdevice)) { 1112 err = xen_translate_vdev(info->vdevice, &minor, &offset); 1113 if (err) 1114 return err; 1115 nr_parts = PARTS_PER_DISK; 1116 } else { 1117 minor = BLKIF_MINOR_EXT(info->vdevice); 1118 nr_parts = PARTS_PER_EXT_DISK; 1119 offset = minor / nr_parts; 1120 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 1121 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 1122 "emulated IDE disks,\n\t choose an xvd device name" 1123 "from xvde on\n", info->vdevice); 1124 } 1125 if (minor >> MINORBITS) { 1126 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 1127 info->vdevice, minor); 1128 return -ENODEV; 1129 } 1130 1131 if ((minor % nr_parts) == 0) 1132 nr_minors = nr_parts; 1133 1134 err = xlbd_reserve_minors(minor, nr_minors); 1135 if (err) 1136 goto out; 1137 err = -ENODEV; 1138 1139 gd = alloc_disk(nr_minors); 1140 if (gd == NULL) 1141 goto release; 1142 1143 strcpy(gd->disk_name, DEV_NAME); 1144 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 1145 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 1146 if (nr_minors > 1) 1147 *ptr = 0; 1148 else 1149 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 1150 "%d", minor & (nr_parts - 1)); 1151 1152 gd->major = XENVBD_MAJOR; 1153 gd->first_minor = minor; 1154 gd->fops = &xlvbd_block_fops; 1155 gd->private_data = info; 1156 set_capacity(gd, capacity); 1157 1158 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) { 1159 del_gendisk(gd); 1160 goto release; 1161 } 1162 1163 xlvbd_flush(info); 1164 1165 if (vdisk_info & VDISK_READONLY) 1166 set_disk_ro(gd, 1); 1167 1168 if (vdisk_info & VDISK_REMOVABLE) 1169 gd->flags |= GENHD_FL_REMOVABLE; 1170 1171 if (vdisk_info & VDISK_CDROM) 1172 gd->flags |= GENHD_FL_CD; 1173 1174 return 0; 1175 1176 release: 1177 xlbd_release_minors(minor, nr_minors); 1178 out: 1179 return err; 1180 } 1181 1182 static void xlvbd_release_gendisk(struct blkfront_info *info) 1183 { 1184 unsigned int minor, nr_minors, i; 1185 1186 if (info->rq == NULL) 1187 return; 1188 1189 /* No more blkif_request(). */ 1190 blk_mq_stop_hw_queues(info->rq); 1191 1192 for (i = 0; i < info->nr_rings; i++) { 1193 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1194 1195 /* No more gnttab callback work. */ 1196 gnttab_cancel_free_callback(&rinfo->callback); 1197 1198 /* Flush gnttab callback work. Must be done with no locks held. */ 1199 flush_work(&rinfo->work); 1200 } 1201 1202 del_gendisk(info->gd); 1203 1204 minor = info->gd->first_minor; 1205 nr_minors = info->gd->minors; 1206 xlbd_release_minors(minor, nr_minors); 1207 1208 blk_cleanup_queue(info->rq); 1209 blk_mq_free_tag_set(&info->tag_set); 1210 info->rq = NULL; 1211 1212 put_disk(info->gd); 1213 info->gd = NULL; 1214 } 1215 1216 /* Already hold rinfo->ring_lock. */ 1217 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo) 1218 { 1219 if (!RING_FULL(&rinfo->ring)) 1220 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true); 1221 } 1222 1223 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo) 1224 { 1225 unsigned long flags; 1226 1227 spin_lock_irqsave(&rinfo->ring_lock, flags); 1228 kick_pending_request_queues_locked(rinfo); 1229 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1230 } 1231 1232 static void blkif_restart_queue(struct work_struct *work) 1233 { 1234 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work); 1235 1236 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED) 1237 kick_pending_request_queues(rinfo); 1238 } 1239 1240 static void blkif_free_ring(struct blkfront_ring_info *rinfo) 1241 { 1242 struct grant *persistent_gnt, *n; 1243 struct blkfront_info *info = rinfo->dev_info; 1244 int i, j, segs; 1245 1246 /* 1247 * Remove indirect pages, this only happens when using indirect 1248 * descriptors but not persistent grants 1249 */ 1250 if (!list_empty(&rinfo->indirect_pages)) { 1251 struct page *indirect_page, *n; 1252 1253 BUG_ON(info->feature_persistent); 1254 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 1255 list_del(&indirect_page->lru); 1256 __free_page(indirect_page); 1257 } 1258 } 1259 1260 /* Remove all persistent grants. */ 1261 if (!list_empty(&rinfo->grants)) { 1262 list_for_each_entry_safe(persistent_gnt, n, 1263 &rinfo->grants, node) { 1264 list_del(&persistent_gnt->node); 1265 if (persistent_gnt->gref != GRANT_INVALID_REF) { 1266 gnttab_end_foreign_access(persistent_gnt->gref, 1267 0, 0UL); 1268 rinfo->persistent_gnts_c--; 1269 } 1270 if (info->feature_persistent) 1271 __free_page(persistent_gnt->page); 1272 kfree(persistent_gnt); 1273 } 1274 } 1275 BUG_ON(rinfo->persistent_gnts_c != 0); 1276 1277 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1278 /* 1279 * Clear persistent grants present in requests already 1280 * on the shared ring 1281 */ 1282 if (!rinfo->shadow[i].request) 1283 goto free_shadow; 1284 1285 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 1286 rinfo->shadow[i].req.u.indirect.nr_segments : 1287 rinfo->shadow[i].req.u.rw.nr_segments; 1288 for (j = 0; j < segs; j++) { 1289 persistent_gnt = rinfo->shadow[i].grants_used[j]; 1290 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1291 if (info->feature_persistent) 1292 __free_page(persistent_gnt->page); 1293 kfree(persistent_gnt); 1294 } 1295 1296 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT) 1297 /* 1298 * If this is not an indirect operation don't try to 1299 * free indirect segments 1300 */ 1301 goto free_shadow; 1302 1303 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 1304 persistent_gnt = rinfo->shadow[i].indirect_grants[j]; 1305 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1306 __free_page(persistent_gnt->page); 1307 kfree(persistent_gnt); 1308 } 1309 1310 free_shadow: 1311 kfree(rinfo->shadow[i].grants_used); 1312 rinfo->shadow[i].grants_used = NULL; 1313 kfree(rinfo->shadow[i].indirect_grants); 1314 rinfo->shadow[i].indirect_grants = NULL; 1315 kfree(rinfo->shadow[i].sg); 1316 rinfo->shadow[i].sg = NULL; 1317 } 1318 1319 /* No more gnttab callback work. */ 1320 gnttab_cancel_free_callback(&rinfo->callback); 1321 1322 /* Flush gnttab callback work. Must be done with no locks held. */ 1323 flush_work(&rinfo->work); 1324 1325 /* Free resources associated with old device channel. */ 1326 for (i = 0; i < info->nr_ring_pages; i++) { 1327 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) { 1328 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0); 1329 rinfo->ring_ref[i] = GRANT_INVALID_REF; 1330 } 1331 } 1332 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE)); 1333 rinfo->ring.sring = NULL; 1334 1335 if (rinfo->irq) 1336 unbind_from_irqhandler(rinfo->irq, rinfo); 1337 rinfo->evtchn = rinfo->irq = 0; 1338 } 1339 1340 static void blkif_free(struct blkfront_info *info, int suspend) 1341 { 1342 unsigned int i; 1343 1344 /* Prevent new requests being issued until we fix things up. */ 1345 info->connected = suspend ? 1346 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 1347 /* No more blkif_request(). */ 1348 if (info->rq) 1349 blk_mq_stop_hw_queues(info->rq); 1350 1351 for (i = 0; i < info->nr_rings; i++) 1352 blkif_free_ring(&info->rinfo[i]); 1353 1354 kfree(info->rinfo); 1355 info->rinfo = NULL; 1356 info->nr_rings = 0; 1357 } 1358 1359 struct copy_from_grant { 1360 const struct blk_shadow *s; 1361 unsigned int grant_idx; 1362 unsigned int bvec_offset; 1363 char *bvec_data; 1364 }; 1365 1366 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset, 1367 unsigned int len, void *data) 1368 { 1369 struct copy_from_grant *info = data; 1370 char *shared_data; 1371 /* Convenient aliases */ 1372 const struct blk_shadow *s = info->s; 1373 1374 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page); 1375 1376 memcpy(info->bvec_data + info->bvec_offset, 1377 shared_data + offset, len); 1378 1379 info->bvec_offset += len; 1380 info->grant_idx++; 1381 1382 kunmap_atomic(shared_data); 1383 } 1384 1385 static enum blk_req_status blkif_rsp_to_req_status(int rsp) 1386 { 1387 switch (rsp) 1388 { 1389 case BLKIF_RSP_OKAY: 1390 return REQ_DONE; 1391 case BLKIF_RSP_EOPNOTSUPP: 1392 return REQ_EOPNOTSUPP; 1393 case BLKIF_RSP_ERROR: 1394 /* Fallthrough. */ 1395 default: 1396 return REQ_ERROR; 1397 } 1398 } 1399 1400 /* 1401 * Get the final status of the block request based on two ring response 1402 */ 1403 static int blkif_get_final_status(enum blk_req_status s1, 1404 enum blk_req_status s2) 1405 { 1406 BUG_ON(s1 == REQ_WAITING); 1407 BUG_ON(s2 == REQ_WAITING); 1408 1409 if (s1 == REQ_ERROR || s2 == REQ_ERROR) 1410 return BLKIF_RSP_ERROR; 1411 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP) 1412 return BLKIF_RSP_EOPNOTSUPP; 1413 return BLKIF_RSP_OKAY; 1414 } 1415 1416 static bool blkif_completion(unsigned long *id, 1417 struct blkfront_ring_info *rinfo, 1418 struct blkif_response *bret) 1419 { 1420 int i = 0; 1421 struct scatterlist *sg; 1422 int num_sg, num_grant; 1423 struct blkfront_info *info = rinfo->dev_info; 1424 struct blk_shadow *s = &rinfo->shadow[*id]; 1425 struct copy_from_grant data = { 1426 .grant_idx = 0, 1427 }; 1428 1429 num_grant = s->req.operation == BLKIF_OP_INDIRECT ? 1430 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1431 1432 /* The I/O request may be split in two. */ 1433 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) { 1434 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id]; 1435 1436 /* Keep the status of the current response in shadow. */ 1437 s->status = blkif_rsp_to_req_status(bret->status); 1438 1439 /* Wait the second response if not yet here. */ 1440 if (s2->status == REQ_WAITING) 1441 return 0; 1442 1443 bret->status = blkif_get_final_status(s->status, 1444 s2->status); 1445 1446 /* 1447 * All the grants is stored in the first shadow in order 1448 * to make the completion code simpler. 1449 */ 1450 num_grant += s2->req.u.rw.nr_segments; 1451 1452 /* 1453 * The two responses may not come in order. Only the 1454 * first request will store the scatter-gather list. 1455 */ 1456 if (s2->num_sg != 0) { 1457 /* Update "id" with the ID of the first response. */ 1458 *id = s->associated_id; 1459 s = s2; 1460 } 1461 1462 /* 1463 * We don't need anymore the second request, so recycling 1464 * it now. 1465 */ 1466 if (add_id_to_freelist(rinfo, s->associated_id)) 1467 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n", 1468 info->gd->disk_name, s->associated_id); 1469 } 1470 1471 data.s = s; 1472 num_sg = s->num_sg; 1473 1474 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { 1475 for_each_sg(s->sg, sg, num_sg, i) { 1476 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1477 1478 data.bvec_offset = sg->offset; 1479 data.bvec_data = kmap_atomic(sg_page(sg)); 1480 1481 gnttab_foreach_grant_in_range(sg_page(sg), 1482 sg->offset, 1483 sg->length, 1484 blkif_copy_from_grant, 1485 &data); 1486 1487 kunmap_atomic(data.bvec_data); 1488 } 1489 } 1490 /* Add the persistent grant into the list of free grants */ 1491 for (i = 0; i < num_grant; i++) { 1492 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) { 1493 /* 1494 * If the grant is still mapped by the backend (the 1495 * backend has chosen to make this grant persistent) 1496 * we add it at the head of the list, so it will be 1497 * reused first. 1498 */ 1499 if (!info->feature_persistent) 1500 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1501 s->grants_used[i]->gref); 1502 list_add(&s->grants_used[i]->node, &rinfo->grants); 1503 rinfo->persistent_gnts_c++; 1504 } else { 1505 /* 1506 * If the grant is not mapped by the backend we end the 1507 * foreign access and add it to the tail of the list, 1508 * so it will not be picked again unless we run out of 1509 * persistent grants. 1510 */ 1511 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); 1512 s->grants_used[i]->gref = GRANT_INVALID_REF; 1513 list_add_tail(&s->grants_used[i]->node, &rinfo->grants); 1514 } 1515 } 1516 if (s->req.operation == BLKIF_OP_INDIRECT) { 1517 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) { 1518 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { 1519 if (!info->feature_persistent) 1520 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1521 s->indirect_grants[i]->gref); 1522 list_add(&s->indirect_grants[i]->node, &rinfo->grants); 1523 rinfo->persistent_gnts_c++; 1524 } else { 1525 struct page *indirect_page; 1526 1527 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); 1528 /* 1529 * Add the used indirect page back to the list of 1530 * available pages for indirect grefs. 1531 */ 1532 if (!info->feature_persistent) { 1533 indirect_page = s->indirect_grants[i]->page; 1534 list_add(&indirect_page->lru, &rinfo->indirect_pages); 1535 } 1536 s->indirect_grants[i]->gref = GRANT_INVALID_REF; 1537 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants); 1538 } 1539 } 1540 } 1541 1542 return 1; 1543 } 1544 1545 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1546 { 1547 struct request *req; 1548 struct blkif_response *bret; 1549 RING_IDX i, rp; 1550 unsigned long flags; 1551 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id; 1552 struct blkfront_info *info = rinfo->dev_info; 1553 1554 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 1555 return IRQ_HANDLED; 1556 1557 spin_lock_irqsave(&rinfo->ring_lock, flags); 1558 again: 1559 rp = rinfo->ring.sring->rsp_prod; 1560 rmb(); /* Ensure we see queued responses up to 'rp'. */ 1561 1562 for (i = rinfo->ring.rsp_cons; i != rp; i++) { 1563 unsigned long id; 1564 1565 bret = RING_GET_RESPONSE(&rinfo->ring, i); 1566 id = bret->id; 1567 /* 1568 * The backend has messed up and given us an id that we would 1569 * never have given to it (we stamp it up to BLK_RING_SIZE - 1570 * look in get_id_from_freelist. 1571 */ 1572 if (id >= BLK_RING_SIZE(info)) { 1573 WARN(1, "%s: response to %s has incorrect id (%ld)\n", 1574 info->gd->disk_name, op_name(bret->operation), id); 1575 /* We can't safely get the 'struct request' as 1576 * the id is busted. */ 1577 continue; 1578 } 1579 req = rinfo->shadow[id].request; 1580 1581 if (bret->operation != BLKIF_OP_DISCARD) { 1582 /* 1583 * We may need to wait for an extra response if the 1584 * I/O request is split in 2 1585 */ 1586 if (!blkif_completion(&id, rinfo, bret)) 1587 continue; 1588 } 1589 1590 if (add_id_to_freelist(rinfo, id)) { 1591 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1592 info->gd->disk_name, op_name(bret->operation), id); 1593 continue; 1594 } 1595 1596 if (bret->status == BLKIF_RSP_OKAY) 1597 blkif_req(req)->error = BLK_STS_OK; 1598 else 1599 blkif_req(req)->error = BLK_STS_IOERR; 1600 1601 switch (bret->operation) { 1602 case BLKIF_OP_DISCARD: 1603 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1604 struct request_queue *rq = info->rq; 1605 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1606 info->gd->disk_name, op_name(bret->operation)); 1607 blkif_req(req)->error = BLK_STS_NOTSUPP; 1608 info->feature_discard = 0; 1609 info->feature_secdiscard = 0; 1610 queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 1611 queue_flag_clear(QUEUE_FLAG_SECERASE, rq); 1612 } 1613 break; 1614 case BLKIF_OP_FLUSH_DISKCACHE: 1615 case BLKIF_OP_WRITE_BARRIER: 1616 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1617 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1618 info->gd->disk_name, op_name(bret->operation)); 1619 blkif_req(req)->error = -EOPNOTSUPP; 1620 } 1621 if (unlikely(bret->status == BLKIF_RSP_ERROR && 1622 rinfo->shadow[id].req.u.rw.nr_segments == 0)) { 1623 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", 1624 info->gd->disk_name, op_name(bret->operation)); 1625 blkif_req(req)->error = BLK_STS_NOTSUPP; 1626 } 1627 if (unlikely(blkif_req(req)->error)) { 1628 if (blkif_req(req)->error == BLK_STS_NOTSUPP) 1629 blkif_req(req)->error = BLK_STS_OK; 1630 info->feature_fua = 0; 1631 info->feature_flush = 0; 1632 xlvbd_flush(info); 1633 } 1634 /* fall through */ 1635 case BLKIF_OP_READ: 1636 case BLKIF_OP_WRITE: 1637 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 1638 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 1639 "request: %x\n", bret->status); 1640 1641 break; 1642 default: 1643 BUG(); 1644 } 1645 1646 blk_mq_complete_request(req); 1647 } 1648 1649 rinfo->ring.rsp_cons = i; 1650 1651 if (i != rinfo->ring.req_prod_pvt) { 1652 int more_to_do; 1653 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do); 1654 if (more_to_do) 1655 goto again; 1656 } else 1657 rinfo->ring.sring->rsp_event = i + 1; 1658 1659 kick_pending_request_queues_locked(rinfo); 1660 1661 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1662 1663 return IRQ_HANDLED; 1664 } 1665 1666 1667 static int setup_blkring(struct xenbus_device *dev, 1668 struct blkfront_ring_info *rinfo) 1669 { 1670 struct blkif_sring *sring; 1671 int err, i; 1672 struct blkfront_info *info = rinfo->dev_info; 1673 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE; 1674 grant_ref_t gref[XENBUS_MAX_RING_GRANTS]; 1675 1676 for (i = 0; i < info->nr_ring_pages; i++) 1677 rinfo->ring_ref[i] = GRANT_INVALID_REF; 1678 1679 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH, 1680 get_order(ring_size)); 1681 if (!sring) { 1682 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1683 return -ENOMEM; 1684 } 1685 SHARED_RING_INIT(sring); 1686 FRONT_RING_INIT(&rinfo->ring, sring, ring_size); 1687 1688 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref); 1689 if (err < 0) { 1690 free_pages((unsigned long)sring, get_order(ring_size)); 1691 rinfo->ring.sring = NULL; 1692 goto fail; 1693 } 1694 for (i = 0; i < info->nr_ring_pages; i++) 1695 rinfo->ring_ref[i] = gref[i]; 1696 1697 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn); 1698 if (err) 1699 goto fail; 1700 1701 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0, 1702 "blkif", rinfo); 1703 if (err <= 0) { 1704 xenbus_dev_fatal(dev, err, 1705 "bind_evtchn_to_irqhandler failed"); 1706 goto fail; 1707 } 1708 rinfo->irq = err; 1709 1710 return 0; 1711 fail: 1712 blkif_free(info, 0); 1713 return err; 1714 } 1715 1716 /* 1717 * Write out per-ring/queue nodes including ring-ref and event-channel, and each 1718 * ring buffer may have multi pages depending on ->nr_ring_pages. 1719 */ 1720 static int write_per_ring_nodes(struct xenbus_transaction xbt, 1721 struct blkfront_ring_info *rinfo, const char *dir) 1722 { 1723 int err; 1724 unsigned int i; 1725 const char *message = NULL; 1726 struct blkfront_info *info = rinfo->dev_info; 1727 1728 if (info->nr_ring_pages == 1) { 1729 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]); 1730 if (err) { 1731 message = "writing ring-ref"; 1732 goto abort_transaction; 1733 } 1734 } else { 1735 for (i = 0; i < info->nr_ring_pages; i++) { 1736 char ring_ref_name[RINGREF_NAME_LEN]; 1737 1738 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 1739 err = xenbus_printf(xbt, dir, ring_ref_name, 1740 "%u", rinfo->ring_ref[i]); 1741 if (err) { 1742 message = "writing ring-ref"; 1743 goto abort_transaction; 1744 } 1745 } 1746 } 1747 1748 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn); 1749 if (err) { 1750 message = "writing event-channel"; 1751 goto abort_transaction; 1752 } 1753 1754 return 0; 1755 1756 abort_transaction: 1757 xenbus_transaction_end(xbt, 1); 1758 if (message) 1759 xenbus_dev_fatal(info->xbdev, err, "%s", message); 1760 1761 return err; 1762 } 1763 1764 /* Common code used when first setting up, and when resuming. */ 1765 static int talk_to_blkback(struct xenbus_device *dev, 1766 struct blkfront_info *info) 1767 { 1768 const char *message = NULL; 1769 struct xenbus_transaction xbt; 1770 int err; 1771 unsigned int i, max_page_order; 1772 unsigned int ring_page_order; 1773 1774 max_page_order = xenbus_read_unsigned(info->xbdev->otherend, 1775 "max-ring-page-order", 0); 1776 ring_page_order = min(xen_blkif_max_ring_order, max_page_order); 1777 info->nr_ring_pages = 1 << ring_page_order; 1778 1779 for (i = 0; i < info->nr_rings; i++) { 1780 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1781 1782 /* Create shared ring, alloc event channel. */ 1783 err = setup_blkring(dev, rinfo); 1784 if (err) 1785 goto destroy_blkring; 1786 } 1787 1788 again: 1789 err = xenbus_transaction_start(&xbt); 1790 if (err) { 1791 xenbus_dev_fatal(dev, err, "starting transaction"); 1792 goto destroy_blkring; 1793 } 1794 1795 if (info->nr_ring_pages > 1) { 1796 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u", 1797 ring_page_order); 1798 if (err) { 1799 message = "writing ring-page-order"; 1800 goto abort_transaction; 1801 } 1802 } 1803 1804 /* We already got the number of queues/rings in _probe */ 1805 if (info->nr_rings == 1) { 1806 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename); 1807 if (err) 1808 goto destroy_blkring; 1809 } else { 1810 char *path; 1811 size_t pathsize; 1812 1813 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u", 1814 info->nr_rings); 1815 if (err) { 1816 message = "writing multi-queue-num-queues"; 1817 goto abort_transaction; 1818 } 1819 1820 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN; 1821 path = kmalloc(pathsize, GFP_KERNEL); 1822 if (!path) { 1823 err = -ENOMEM; 1824 message = "ENOMEM while writing ring references"; 1825 goto abort_transaction; 1826 } 1827 1828 for (i = 0; i < info->nr_rings; i++) { 1829 memset(path, 0, pathsize); 1830 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i); 1831 err = write_per_ring_nodes(xbt, &info->rinfo[i], path); 1832 if (err) { 1833 kfree(path); 1834 goto destroy_blkring; 1835 } 1836 } 1837 kfree(path); 1838 } 1839 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1840 XEN_IO_PROTO_ABI_NATIVE); 1841 if (err) { 1842 message = "writing protocol"; 1843 goto abort_transaction; 1844 } 1845 err = xenbus_printf(xbt, dev->nodename, 1846 "feature-persistent", "%u", 1); 1847 if (err) 1848 dev_warn(&dev->dev, 1849 "writing persistent grants feature to xenbus"); 1850 1851 err = xenbus_transaction_end(xbt, 0); 1852 if (err) { 1853 if (err == -EAGAIN) 1854 goto again; 1855 xenbus_dev_fatal(dev, err, "completing transaction"); 1856 goto destroy_blkring; 1857 } 1858 1859 for (i = 0; i < info->nr_rings; i++) { 1860 unsigned int j; 1861 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1862 1863 for (j = 0; j < BLK_RING_SIZE(info); j++) 1864 rinfo->shadow[j].req.u.rw.id = j + 1; 1865 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 1866 } 1867 xenbus_switch_state(dev, XenbusStateInitialised); 1868 1869 return 0; 1870 1871 abort_transaction: 1872 xenbus_transaction_end(xbt, 1); 1873 if (message) 1874 xenbus_dev_fatal(dev, err, "%s", message); 1875 destroy_blkring: 1876 blkif_free(info, 0); 1877 1878 kfree(info); 1879 dev_set_drvdata(&dev->dev, NULL); 1880 1881 return err; 1882 } 1883 1884 static int negotiate_mq(struct blkfront_info *info) 1885 { 1886 unsigned int backend_max_queues; 1887 unsigned int i; 1888 1889 BUG_ON(info->nr_rings); 1890 1891 /* Check if backend supports multiple queues. */ 1892 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend, 1893 "multi-queue-max-queues", 1); 1894 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues); 1895 /* We need at least one ring. */ 1896 if (!info->nr_rings) 1897 info->nr_rings = 1; 1898 1899 info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL); 1900 if (!info->rinfo) { 1901 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure"); 1902 return -ENOMEM; 1903 } 1904 1905 for (i = 0; i < info->nr_rings; i++) { 1906 struct blkfront_ring_info *rinfo; 1907 1908 rinfo = &info->rinfo[i]; 1909 INIT_LIST_HEAD(&rinfo->indirect_pages); 1910 INIT_LIST_HEAD(&rinfo->grants); 1911 rinfo->dev_info = info; 1912 INIT_WORK(&rinfo->work, blkif_restart_queue); 1913 spin_lock_init(&rinfo->ring_lock); 1914 } 1915 return 0; 1916 } 1917 /** 1918 * Entry point to this code when a new device is created. Allocate the basic 1919 * structures and the ring buffer for communication with the backend, and 1920 * inform the backend of the appropriate details for those. Switch to 1921 * Initialised state. 1922 */ 1923 static int blkfront_probe(struct xenbus_device *dev, 1924 const struct xenbus_device_id *id) 1925 { 1926 int err, vdevice; 1927 struct blkfront_info *info; 1928 1929 /* FIXME: Use dynamic device id if this is not set. */ 1930 err = xenbus_scanf(XBT_NIL, dev->nodename, 1931 "virtual-device", "%i", &vdevice); 1932 if (err != 1) { 1933 /* go looking in the extended area instead */ 1934 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1935 "%i", &vdevice); 1936 if (err != 1) { 1937 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1938 return err; 1939 } 1940 } 1941 1942 if (xen_hvm_domain()) { 1943 char *type; 1944 int len; 1945 /* no unplug has been done: do not hook devices != xen vbds */ 1946 if (xen_has_pv_and_legacy_disk_devices()) { 1947 int major; 1948 1949 if (!VDEV_IS_EXTENDED(vdevice)) 1950 major = BLKIF_MAJOR(vdevice); 1951 else 1952 major = XENVBD_MAJOR; 1953 1954 if (major != XENVBD_MAJOR) { 1955 printk(KERN_INFO 1956 "%s: HVM does not support vbd %d as xen block device\n", 1957 __func__, vdevice); 1958 return -ENODEV; 1959 } 1960 } 1961 /* do not create a PV cdrom device if we are an HVM guest */ 1962 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1963 if (IS_ERR(type)) 1964 return -ENODEV; 1965 if (strncmp(type, "cdrom", 5) == 0) { 1966 kfree(type); 1967 return -ENODEV; 1968 } 1969 kfree(type); 1970 } 1971 info = kzalloc(sizeof(*info), GFP_KERNEL); 1972 if (!info) { 1973 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1974 return -ENOMEM; 1975 } 1976 1977 info->xbdev = dev; 1978 err = negotiate_mq(info); 1979 if (err) { 1980 kfree(info); 1981 return err; 1982 } 1983 1984 mutex_init(&info->mutex); 1985 info->vdevice = vdevice; 1986 info->connected = BLKIF_STATE_DISCONNECTED; 1987 1988 /* Front end dir is a number, which is used as the id. */ 1989 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1990 dev_set_drvdata(&dev->dev, info); 1991 1992 return 0; 1993 } 1994 1995 static int blkif_recover(struct blkfront_info *info) 1996 { 1997 unsigned int r_index; 1998 struct request *req, *n; 1999 int rc; 2000 struct bio *bio; 2001 unsigned int segs; 2002 2003 blkfront_gather_backend_features(info); 2004 /* Reset limits changed by blk_mq_update_nr_hw_queues(). */ 2005 blkif_set_queue_limits(info); 2006 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 2007 blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG); 2008 2009 for (r_index = 0; r_index < info->nr_rings; r_index++) { 2010 struct blkfront_ring_info *rinfo = &info->rinfo[r_index]; 2011 2012 rc = blkfront_setup_indirect(rinfo); 2013 if (rc) 2014 return rc; 2015 } 2016 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2017 2018 /* Now safe for us to use the shared ring */ 2019 info->connected = BLKIF_STATE_CONNECTED; 2020 2021 for (r_index = 0; r_index < info->nr_rings; r_index++) { 2022 struct blkfront_ring_info *rinfo; 2023 2024 rinfo = &info->rinfo[r_index]; 2025 /* Kick any other new requests queued since we resumed */ 2026 kick_pending_request_queues(rinfo); 2027 } 2028 2029 list_for_each_entry_safe(req, n, &info->requests, queuelist) { 2030 /* Requeue pending requests (flush or discard) */ 2031 list_del_init(&req->queuelist); 2032 BUG_ON(req->nr_phys_segments > segs); 2033 blk_mq_requeue_request(req, false); 2034 } 2035 blk_mq_start_stopped_hw_queues(info->rq, true); 2036 blk_mq_kick_requeue_list(info->rq); 2037 2038 while ((bio = bio_list_pop(&info->bio_list)) != NULL) { 2039 /* Traverse the list of pending bios and re-queue them */ 2040 submit_bio(bio); 2041 } 2042 2043 return 0; 2044 } 2045 2046 /** 2047 * We are reconnecting to the backend, due to a suspend/resume, or a backend 2048 * driver restart. We tear down our blkif structure and recreate it, but 2049 * leave the device-layer structures intact so that this is transparent to the 2050 * rest of the kernel. 2051 */ 2052 static int blkfront_resume(struct xenbus_device *dev) 2053 { 2054 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2055 int err = 0; 2056 unsigned int i, j; 2057 2058 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 2059 2060 bio_list_init(&info->bio_list); 2061 INIT_LIST_HEAD(&info->requests); 2062 for (i = 0; i < info->nr_rings; i++) { 2063 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 2064 struct bio_list merge_bio; 2065 struct blk_shadow *shadow = rinfo->shadow; 2066 2067 for (j = 0; j < BLK_RING_SIZE(info); j++) { 2068 /* Not in use? */ 2069 if (!shadow[j].request) 2070 continue; 2071 2072 /* 2073 * Get the bios in the request so we can re-queue them. 2074 */ 2075 if (req_op(shadow[i].request) == REQ_OP_FLUSH || 2076 req_op(shadow[i].request) == REQ_OP_DISCARD || 2077 req_op(shadow[i].request) == REQ_OP_SECURE_ERASE || 2078 shadow[j].request->cmd_flags & REQ_FUA) { 2079 /* 2080 * Flush operations don't contain bios, so 2081 * we need to requeue the whole request 2082 * 2083 * XXX: but this doesn't make any sense for a 2084 * write with the FUA flag set.. 2085 */ 2086 list_add(&shadow[j].request->queuelist, &info->requests); 2087 continue; 2088 } 2089 merge_bio.head = shadow[j].request->bio; 2090 merge_bio.tail = shadow[j].request->biotail; 2091 bio_list_merge(&info->bio_list, &merge_bio); 2092 shadow[j].request->bio = NULL; 2093 blk_mq_end_request(shadow[j].request, BLK_STS_OK); 2094 } 2095 } 2096 2097 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 2098 2099 err = negotiate_mq(info); 2100 if (err) 2101 return err; 2102 2103 err = talk_to_blkback(dev, info); 2104 if (!err) 2105 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings); 2106 2107 /* 2108 * We have to wait for the backend to switch to 2109 * connected state, since we want to read which 2110 * features it supports. 2111 */ 2112 2113 return err; 2114 } 2115 2116 static void blkfront_closing(struct blkfront_info *info) 2117 { 2118 struct xenbus_device *xbdev = info->xbdev; 2119 struct block_device *bdev = NULL; 2120 2121 mutex_lock(&info->mutex); 2122 2123 if (xbdev->state == XenbusStateClosing) { 2124 mutex_unlock(&info->mutex); 2125 return; 2126 } 2127 2128 if (info->gd) 2129 bdev = bdget_disk(info->gd, 0); 2130 2131 mutex_unlock(&info->mutex); 2132 2133 if (!bdev) { 2134 xenbus_frontend_closed(xbdev); 2135 return; 2136 } 2137 2138 mutex_lock(&bdev->bd_mutex); 2139 2140 if (bdev->bd_openers) { 2141 xenbus_dev_error(xbdev, -EBUSY, 2142 "Device in use; refusing to close"); 2143 xenbus_switch_state(xbdev, XenbusStateClosing); 2144 } else { 2145 xlvbd_release_gendisk(info); 2146 xenbus_frontend_closed(xbdev); 2147 } 2148 2149 mutex_unlock(&bdev->bd_mutex); 2150 bdput(bdev); 2151 } 2152 2153 static void blkfront_setup_discard(struct blkfront_info *info) 2154 { 2155 int err; 2156 unsigned int discard_granularity; 2157 unsigned int discard_alignment; 2158 2159 info->feature_discard = 1; 2160 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2161 "discard-granularity", "%u", &discard_granularity, 2162 "discard-alignment", "%u", &discard_alignment, 2163 NULL); 2164 if (!err) { 2165 info->discard_granularity = discard_granularity; 2166 info->discard_alignment = discard_alignment; 2167 } 2168 info->feature_secdiscard = 2169 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure", 2170 0); 2171 } 2172 2173 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo) 2174 { 2175 unsigned int psegs, grants; 2176 int err, i; 2177 struct blkfront_info *info = rinfo->dev_info; 2178 2179 if (info->max_indirect_segments == 0) { 2180 if (!HAS_EXTRA_REQ) 2181 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2182 else { 2183 /* 2184 * When an extra req is required, the maximum 2185 * grants supported is related to the size of the 2186 * Linux block segment. 2187 */ 2188 grants = GRANTS_PER_PSEG; 2189 } 2190 } 2191 else 2192 grants = info->max_indirect_segments; 2193 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG); 2194 2195 err = fill_grant_buffer(rinfo, 2196 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info)); 2197 if (err) 2198 goto out_of_memory; 2199 2200 if (!info->feature_persistent && info->max_indirect_segments) { 2201 /* 2202 * We are using indirect descriptors but not persistent 2203 * grants, we need to allocate a set of pages that can be 2204 * used for mapping indirect grefs 2205 */ 2206 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info); 2207 2208 BUG_ON(!list_empty(&rinfo->indirect_pages)); 2209 for (i = 0; i < num; i++) { 2210 struct page *indirect_page = alloc_page(GFP_NOIO); 2211 if (!indirect_page) 2212 goto out_of_memory; 2213 list_add(&indirect_page->lru, &rinfo->indirect_pages); 2214 } 2215 } 2216 2217 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2218 rinfo->shadow[i].grants_used = kzalloc( 2219 sizeof(rinfo->shadow[i].grants_used[0]) * grants, 2220 GFP_NOIO); 2221 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO); 2222 if (info->max_indirect_segments) 2223 rinfo->shadow[i].indirect_grants = kzalloc( 2224 sizeof(rinfo->shadow[i].indirect_grants[0]) * 2225 INDIRECT_GREFS(grants), 2226 GFP_NOIO); 2227 if ((rinfo->shadow[i].grants_used == NULL) || 2228 (rinfo->shadow[i].sg == NULL) || 2229 (info->max_indirect_segments && 2230 (rinfo->shadow[i].indirect_grants == NULL))) 2231 goto out_of_memory; 2232 sg_init_table(rinfo->shadow[i].sg, psegs); 2233 } 2234 2235 2236 return 0; 2237 2238 out_of_memory: 2239 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2240 kfree(rinfo->shadow[i].grants_used); 2241 rinfo->shadow[i].grants_used = NULL; 2242 kfree(rinfo->shadow[i].sg); 2243 rinfo->shadow[i].sg = NULL; 2244 kfree(rinfo->shadow[i].indirect_grants); 2245 rinfo->shadow[i].indirect_grants = NULL; 2246 } 2247 if (!list_empty(&rinfo->indirect_pages)) { 2248 struct page *indirect_page, *n; 2249 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 2250 list_del(&indirect_page->lru); 2251 __free_page(indirect_page); 2252 } 2253 } 2254 return -ENOMEM; 2255 } 2256 2257 /* 2258 * Gather all backend feature-* 2259 */ 2260 static void blkfront_gather_backend_features(struct blkfront_info *info) 2261 { 2262 unsigned int indirect_segments; 2263 2264 info->feature_flush = 0; 2265 info->feature_fua = 0; 2266 2267 /* 2268 * If there's no "feature-barrier" defined, then it means 2269 * we're dealing with a very old backend which writes 2270 * synchronously; nothing to do. 2271 * 2272 * If there are barriers, then we use flush. 2273 */ 2274 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) { 2275 info->feature_flush = 1; 2276 info->feature_fua = 1; 2277 } 2278 2279 /* 2280 * And if there is "feature-flush-cache" use that above 2281 * barriers. 2282 */ 2283 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache", 2284 0)) { 2285 info->feature_flush = 1; 2286 info->feature_fua = 0; 2287 } 2288 2289 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) 2290 blkfront_setup_discard(info); 2291 2292 info->feature_persistent = 2293 !!xenbus_read_unsigned(info->xbdev->otherend, 2294 "feature-persistent", 0); 2295 2296 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend, 2297 "feature-max-indirect-segments", 0); 2298 if (indirect_segments > xen_blkif_max_segments) 2299 indirect_segments = xen_blkif_max_segments; 2300 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST) 2301 indirect_segments = 0; 2302 info->max_indirect_segments = indirect_segments; 2303 } 2304 2305 /* 2306 * Invoked when the backend is finally 'ready' (and has told produced 2307 * the details about the physical device - #sectors, size, etc). 2308 */ 2309 static void blkfront_connect(struct blkfront_info *info) 2310 { 2311 unsigned long long sectors; 2312 unsigned long sector_size; 2313 unsigned int physical_sector_size; 2314 unsigned int binfo; 2315 char *envp[] = { "RESIZE=1", NULL }; 2316 int err, i; 2317 2318 switch (info->connected) { 2319 case BLKIF_STATE_CONNECTED: 2320 /* 2321 * Potentially, the back-end may be signalling 2322 * a capacity change; update the capacity. 2323 */ 2324 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2325 "sectors", "%Lu", §ors); 2326 if (XENBUS_EXIST_ERR(err)) 2327 return; 2328 printk(KERN_INFO "Setting capacity to %Lu\n", 2329 sectors); 2330 set_capacity(info->gd, sectors); 2331 revalidate_disk(info->gd); 2332 kobject_uevent_env(&disk_to_dev(info->gd)->kobj, 2333 KOBJ_CHANGE, envp); 2334 2335 return; 2336 case BLKIF_STATE_SUSPENDED: 2337 /* 2338 * If we are recovering from suspension, we need to wait 2339 * for the backend to announce it's features before 2340 * reconnecting, at least we need to know if the backend 2341 * supports indirect descriptors, and how many. 2342 */ 2343 blkif_recover(info); 2344 return; 2345 2346 default: 2347 break; 2348 } 2349 2350 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 2351 __func__, info->xbdev->otherend); 2352 2353 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2354 "sectors", "%llu", §ors, 2355 "info", "%u", &binfo, 2356 "sector-size", "%lu", §or_size, 2357 NULL); 2358 if (err) { 2359 xenbus_dev_fatal(info->xbdev, err, 2360 "reading backend fields at %s", 2361 info->xbdev->otherend); 2362 return; 2363 } 2364 2365 /* 2366 * physcial-sector-size is a newer field, so old backends may not 2367 * provide this. Assume physical sector size to be the same as 2368 * sector_size in that case. 2369 */ 2370 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend, 2371 "physical-sector-size", 2372 sector_size); 2373 blkfront_gather_backend_features(info); 2374 for (i = 0; i < info->nr_rings; i++) { 2375 err = blkfront_setup_indirect(&info->rinfo[i]); 2376 if (err) { 2377 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 2378 info->xbdev->otherend); 2379 blkif_free(info, 0); 2380 break; 2381 } 2382 } 2383 2384 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 2385 physical_sector_size); 2386 if (err) { 2387 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 2388 info->xbdev->otherend); 2389 goto fail; 2390 } 2391 2392 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2393 2394 /* Kick pending requests. */ 2395 info->connected = BLKIF_STATE_CONNECTED; 2396 for (i = 0; i < info->nr_rings; i++) 2397 kick_pending_request_queues(&info->rinfo[i]); 2398 2399 device_add_disk(&info->xbdev->dev, info->gd); 2400 2401 info->is_ready = 1; 2402 return; 2403 2404 fail: 2405 blkif_free(info, 0); 2406 return; 2407 } 2408 2409 /** 2410 * Callback received when the backend's state changes. 2411 */ 2412 static void blkback_changed(struct xenbus_device *dev, 2413 enum xenbus_state backend_state) 2414 { 2415 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2416 2417 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 2418 2419 switch (backend_state) { 2420 case XenbusStateInitWait: 2421 if (dev->state != XenbusStateInitialising) 2422 break; 2423 if (talk_to_blkback(dev, info)) 2424 break; 2425 case XenbusStateInitialising: 2426 case XenbusStateInitialised: 2427 case XenbusStateReconfiguring: 2428 case XenbusStateReconfigured: 2429 case XenbusStateUnknown: 2430 break; 2431 2432 case XenbusStateConnected: 2433 /* 2434 * talk_to_blkback sets state to XenbusStateInitialised 2435 * and blkfront_connect sets it to XenbusStateConnected 2436 * (if connection went OK). 2437 * 2438 * If the backend (or toolstack) decides to poke at backend 2439 * state (and re-trigger the watch by setting the state repeatedly 2440 * to XenbusStateConnected (4)) we need to deal with this. 2441 * This is allowed as this is used to communicate to the guest 2442 * that the size of disk has changed! 2443 */ 2444 if ((dev->state != XenbusStateInitialised) && 2445 (dev->state != XenbusStateConnected)) { 2446 if (talk_to_blkback(dev, info)) 2447 break; 2448 } 2449 2450 blkfront_connect(info); 2451 break; 2452 2453 case XenbusStateClosed: 2454 if (dev->state == XenbusStateClosed) 2455 break; 2456 /* Missed the backend's Closing state -- fallthrough */ 2457 case XenbusStateClosing: 2458 if (info) 2459 blkfront_closing(info); 2460 break; 2461 } 2462 } 2463 2464 static int blkfront_remove(struct xenbus_device *xbdev) 2465 { 2466 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 2467 struct block_device *bdev = NULL; 2468 struct gendisk *disk; 2469 2470 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 2471 2472 blkif_free(info, 0); 2473 2474 mutex_lock(&info->mutex); 2475 2476 disk = info->gd; 2477 if (disk) 2478 bdev = bdget_disk(disk, 0); 2479 2480 info->xbdev = NULL; 2481 mutex_unlock(&info->mutex); 2482 2483 if (!bdev) { 2484 kfree(info); 2485 return 0; 2486 } 2487 2488 /* 2489 * The xbdev was removed before we reached the Closed 2490 * state. See if it's safe to remove the disk. If the bdev 2491 * isn't closed yet, we let release take care of it. 2492 */ 2493 2494 mutex_lock(&bdev->bd_mutex); 2495 info = disk->private_data; 2496 2497 dev_warn(disk_to_dev(disk), 2498 "%s was hot-unplugged, %d stale handles\n", 2499 xbdev->nodename, bdev->bd_openers); 2500 2501 if (info && !bdev->bd_openers) { 2502 xlvbd_release_gendisk(info); 2503 disk->private_data = NULL; 2504 kfree(info); 2505 } 2506 2507 mutex_unlock(&bdev->bd_mutex); 2508 bdput(bdev); 2509 2510 return 0; 2511 } 2512 2513 static int blkfront_is_ready(struct xenbus_device *dev) 2514 { 2515 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2516 2517 return info->is_ready && info->xbdev; 2518 } 2519 2520 static int blkif_open(struct block_device *bdev, fmode_t mode) 2521 { 2522 struct gendisk *disk = bdev->bd_disk; 2523 struct blkfront_info *info; 2524 int err = 0; 2525 2526 mutex_lock(&blkfront_mutex); 2527 2528 info = disk->private_data; 2529 if (!info) { 2530 /* xbdev gone */ 2531 err = -ERESTARTSYS; 2532 goto out; 2533 } 2534 2535 mutex_lock(&info->mutex); 2536 2537 if (!info->gd) 2538 /* xbdev is closed */ 2539 err = -ERESTARTSYS; 2540 2541 mutex_unlock(&info->mutex); 2542 2543 out: 2544 mutex_unlock(&blkfront_mutex); 2545 return err; 2546 } 2547 2548 static void blkif_release(struct gendisk *disk, fmode_t mode) 2549 { 2550 struct blkfront_info *info = disk->private_data; 2551 struct block_device *bdev; 2552 struct xenbus_device *xbdev; 2553 2554 mutex_lock(&blkfront_mutex); 2555 2556 bdev = bdget_disk(disk, 0); 2557 2558 if (!bdev) { 2559 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2560 goto out_mutex; 2561 } 2562 if (bdev->bd_openers) 2563 goto out; 2564 2565 /* 2566 * Check if we have been instructed to close. We will have 2567 * deferred this request, because the bdev was still open. 2568 */ 2569 2570 mutex_lock(&info->mutex); 2571 xbdev = info->xbdev; 2572 2573 if (xbdev && xbdev->state == XenbusStateClosing) { 2574 /* pending switch to state closed */ 2575 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2576 xlvbd_release_gendisk(info); 2577 xenbus_frontend_closed(info->xbdev); 2578 } 2579 2580 mutex_unlock(&info->mutex); 2581 2582 if (!xbdev) { 2583 /* sudden device removal */ 2584 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2585 xlvbd_release_gendisk(info); 2586 disk->private_data = NULL; 2587 kfree(info); 2588 } 2589 2590 out: 2591 bdput(bdev); 2592 out_mutex: 2593 mutex_unlock(&blkfront_mutex); 2594 } 2595 2596 static const struct block_device_operations xlvbd_block_fops = 2597 { 2598 .owner = THIS_MODULE, 2599 .open = blkif_open, 2600 .release = blkif_release, 2601 .getgeo = blkif_getgeo, 2602 .ioctl = blkif_ioctl, 2603 }; 2604 2605 2606 static const struct xenbus_device_id blkfront_ids[] = { 2607 { "vbd" }, 2608 { "" } 2609 }; 2610 2611 static struct xenbus_driver blkfront_driver = { 2612 .ids = blkfront_ids, 2613 .probe = blkfront_probe, 2614 .remove = blkfront_remove, 2615 .resume = blkfront_resume, 2616 .otherend_changed = blkback_changed, 2617 .is_ready = blkfront_is_ready, 2618 }; 2619 2620 static int __init xlblk_init(void) 2621 { 2622 int ret; 2623 int nr_cpus = num_online_cpus(); 2624 2625 if (!xen_domain()) 2626 return -ENODEV; 2627 2628 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST) 2629 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2630 2631 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { 2632 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 2633 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); 2634 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 2635 } 2636 2637 if (xen_blkif_max_queues > nr_cpus) { 2638 pr_info("Invalid max_queues (%d), will use default max: %d.\n", 2639 xen_blkif_max_queues, nr_cpus); 2640 xen_blkif_max_queues = nr_cpus; 2641 } 2642 2643 if (!xen_has_pv_disk_devices()) 2644 return -ENODEV; 2645 2646 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2647 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2648 XENVBD_MAJOR, DEV_NAME); 2649 return -ENODEV; 2650 } 2651 2652 ret = xenbus_register_frontend(&blkfront_driver); 2653 if (ret) { 2654 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2655 return ret; 2656 } 2657 2658 return 0; 2659 } 2660 module_init(xlblk_init); 2661 2662 2663 static void __exit xlblk_exit(void) 2664 { 2665 xenbus_unregister_driver(&blkfront_driver); 2666 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2667 kfree(minors); 2668 } 2669 module_exit(xlblk_exit); 2670 2671 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2672 MODULE_LICENSE("GPL"); 2673 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2674 MODULE_ALIAS("xen:vbd"); 2675 MODULE_ALIAS("xenblk"); 2676