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 blk_status_t 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, 0444); 133 MODULE_PARM_DESC(max_indirect_segments, 134 "Maximum amount of segments in indirect requests (default is 32)"); 135 136 static unsigned int xen_blkif_max_queues = 4; 137 module_param_named(max_queues, xen_blkif_max_queues, uint, 0444); 138 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk"); 139 140 /* 141 * Maximum order of pages to be used for the shared ring between front and 142 * backend, 4KB page granularity is used. 143 */ 144 static unsigned int xen_blkif_max_ring_order; 145 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444); 146 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 147 148 #define BLK_RING_SIZE(info) \ 149 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages) 150 151 #define BLK_MAX_RING_SIZE \ 152 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS) 153 154 /* 155 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 156 * characters are enough. Define to 20 to keep consistent with backend. 157 */ 158 #define RINGREF_NAME_LEN (20) 159 /* 160 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters. 161 */ 162 #define QUEUE_NAME_LEN (17) 163 164 /* 165 * Per-ring info. 166 * Every blkfront device can associate with one or more blkfront_ring_info, 167 * depending on how many hardware queues/rings to be used. 168 */ 169 struct blkfront_ring_info { 170 /* Lock to protect data in every ring buffer. */ 171 spinlock_t ring_lock; 172 struct blkif_front_ring ring; 173 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS]; 174 unsigned int evtchn, irq; 175 struct work_struct work; 176 struct gnttab_free_callback callback; 177 struct blk_shadow shadow[BLK_MAX_RING_SIZE]; 178 struct list_head indirect_pages; 179 struct list_head grants; 180 unsigned int persistent_gnts_c; 181 unsigned long shadow_free; 182 struct blkfront_info *dev_info; 183 }; 184 185 /* 186 * We have one of these per vbd, whether ide, scsi or 'other'. They 187 * hang in private_data off the gendisk structure. We may end up 188 * putting all kinds of interesting stuff here :-) 189 */ 190 struct blkfront_info 191 { 192 struct mutex mutex; 193 struct xenbus_device *xbdev; 194 struct gendisk *gd; 195 u16 sector_size; 196 unsigned int physical_sector_size; 197 int vdevice; 198 blkif_vdev_t handle; 199 enum blkif_state connected; 200 /* Number of pages per ring buffer. */ 201 unsigned int nr_ring_pages; 202 struct request_queue *rq; 203 unsigned int feature_flush:1; 204 unsigned int feature_fua:1; 205 unsigned int feature_discard:1; 206 unsigned int feature_secdiscard:1; 207 unsigned int feature_persistent:1; 208 unsigned int discard_granularity; 209 unsigned int discard_alignment; 210 /* Number of 4KB segments handled */ 211 unsigned int max_indirect_segments; 212 int is_ready; 213 struct blk_mq_tag_set tag_set; 214 struct blkfront_ring_info *rinfo; 215 unsigned int nr_rings; 216 /* Save uncomplete reqs and bios for migration. */ 217 struct list_head requests; 218 struct bio_list bio_list; 219 }; 220 221 static unsigned int nr_minors; 222 static unsigned long *minors; 223 static DEFINE_SPINLOCK(minor_lock); 224 225 #define GRANT_INVALID_REF 0 226 227 #define PARTS_PER_DISK 16 228 #define PARTS_PER_EXT_DISK 256 229 230 #define BLKIF_MAJOR(dev) ((dev)>>8) 231 #define BLKIF_MINOR(dev) ((dev) & 0xff) 232 233 #define EXT_SHIFT 28 234 #define EXTENDED (1<<EXT_SHIFT) 235 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 236 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 237 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 238 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 239 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 240 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 241 242 #define DEV_NAME "xvd" /* name in /dev */ 243 244 /* 245 * Grants are always the same size as a Xen page (i.e 4KB). 246 * A physical segment is always the same size as a Linux page. 247 * Number of grants per physical segment 248 */ 249 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE) 250 251 #define GRANTS_PER_INDIRECT_FRAME \ 252 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment)) 253 254 #define INDIRECT_GREFS(_grants) \ 255 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME) 256 257 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo); 258 static void blkfront_gather_backend_features(struct blkfront_info *info); 259 static int negotiate_mq(struct blkfront_info *info); 260 261 static int get_id_from_freelist(struct blkfront_ring_info *rinfo) 262 { 263 unsigned long free = rinfo->shadow_free; 264 265 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info)); 266 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id; 267 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 268 return free; 269 } 270 271 static int add_id_to_freelist(struct blkfront_ring_info *rinfo, 272 unsigned long id) 273 { 274 if (rinfo->shadow[id].req.u.rw.id != id) 275 return -EINVAL; 276 if (rinfo->shadow[id].request == NULL) 277 return -EINVAL; 278 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free; 279 rinfo->shadow[id].request = NULL; 280 rinfo->shadow_free = id; 281 return 0; 282 } 283 284 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 285 { 286 struct blkfront_info *info = rinfo->dev_info; 287 struct page *granted_page; 288 struct grant *gnt_list_entry, *n; 289 int i = 0; 290 291 while (i < num) { 292 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 293 if (!gnt_list_entry) 294 goto out_of_memory; 295 296 if (info->feature_persistent) { 297 granted_page = alloc_page(GFP_NOIO); 298 if (!granted_page) { 299 kfree(gnt_list_entry); 300 goto out_of_memory; 301 } 302 gnt_list_entry->page = granted_page; 303 } 304 305 gnt_list_entry->gref = GRANT_INVALID_REF; 306 list_add(&gnt_list_entry->node, &rinfo->grants); 307 i++; 308 } 309 310 return 0; 311 312 out_of_memory: 313 list_for_each_entry_safe(gnt_list_entry, n, 314 &rinfo->grants, node) { 315 list_del(&gnt_list_entry->node); 316 if (info->feature_persistent) 317 __free_page(gnt_list_entry->page); 318 kfree(gnt_list_entry); 319 i--; 320 } 321 BUG_ON(i != 0); 322 return -ENOMEM; 323 } 324 325 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo) 326 { 327 struct grant *gnt_list_entry; 328 329 BUG_ON(list_empty(&rinfo->grants)); 330 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant, 331 node); 332 list_del(&gnt_list_entry->node); 333 334 if (gnt_list_entry->gref != GRANT_INVALID_REF) 335 rinfo->persistent_gnts_c--; 336 337 return gnt_list_entry; 338 } 339 340 static inline void grant_foreign_access(const struct grant *gnt_list_entry, 341 const struct blkfront_info *info) 342 { 343 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref, 344 info->xbdev->otherend_id, 345 gnt_list_entry->page, 346 0); 347 } 348 349 static struct grant *get_grant(grant_ref_t *gref_head, 350 unsigned long gfn, 351 struct blkfront_ring_info *rinfo) 352 { 353 struct grant *gnt_list_entry = get_free_grant(rinfo); 354 struct blkfront_info *info = rinfo->dev_info; 355 356 if (gnt_list_entry->gref != GRANT_INVALID_REF) 357 return gnt_list_entry; 358 359 /* Assign a gref to this page */ 360 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 361 BUG_ON(gnt_list_entry->gref == -ENOSPC); 362 if (info->feature_persistent) 363 grant_foreign_access(gnt_list_entry, info); 364 else { 365 /* Grant access to the GFN passed by the caller */ 366 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 367 info->xbdev->otherend_id, 368 gfn, 0); 369 } 370 371 return gnt_list_entry; 372 } 373 374 static struct grant *get_indirect_grant(grant_ref_t *gref_head, 375 struct blkfront_ring_info *rinfo) 376 { 377 struct grant *gnt_list_entry = get_free_grant(rinfo); 378 struct blkfront_info *info = rinfo->dev_info; 379 380 if (gnt_list_entry->gref != GRANT_INVALID_REF) 381 return gnt_list_entry; 382 383 /* Assign a gref to this page */ 384 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 385 BUG_ON(gnt_list_entry->gref == -ENOSPC); 386 if (!info->feature_persistent) { 387 struct page *indirect_page; 388 389 /* Fetch a pre-allocated page to use for indirect grefs */ 390 BUG_ON(list_empty(&rinfo->indirect_pages)); 391 indirect_page = list_first_entry(&rinfo->indirect_pages, 392 struct page, lru); 393 list_del(&indirect_page->lru); 394 gnt_list_entry->page = indirect_page; 395 } 396 grant_foreign_access(gnt_list_entry, info); 397 398 return gnt_list_entry; 399 } 400 401 static const char *op_name(int op) 402 { 403 static const char *const names[] = { 404 [BLKIF_OP_READ] = "read", 405 [BLKIF_OP_WRITE] = "write", 406 [BLKIF_OP_WRITE_BARRIER] = "barrier", 407 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 408 [BLKIF_OP_DISCARD] = "discard" }; 409 410 if (op < 0 || op >= ARRAY_SIZE(names)) 411 return "unknown"; 412 413 if (!names[op]) 414 return "reserved"; 415 416 return names[op]; 417 } 418 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 419 { 420 unsigned int end = minor + nr; 421 int rc; 422 423 if (end > nr_minors) { 424 unsigned long *bitmap, *old; 425 426 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 427 GFP_KERNEL); 428 if (bitmap == NULL) 429 return -ENOMEM; 430 431 spin_lock(&minor_lock); 432 if (end > nr_minors) { 433 old = minors; 434 memcpy(bitmap, minors, 435 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 436 minors = bitmap; 437 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 438 } else 439 old = bitmap; 440 spin_unlock(&minor_lock); 441 kfree(old); 442 } 443 444 spin_lock(&minor_lock); 445 if (find_next_bit(minors, end, minor) >= end) { 446 bitmap_set(minors, minor, nr); 447 rc = 0; 448 } else 449 rc = -EBUSY; 450 spin_unlock(&minor_lock); 451 452 return rc; 453 } 454 455 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 456 { 457 unsigned int end = minor + nr; 458 459 BUG_ON(end > nr_minors); 460 spin_lock(&minor_lock); 461 bitmap_clear(minors, minor, nr); 462 spin_unlock(&minor_lock); 463 } 464 465 static void blkif_restart_queue_callback(void *arg) 466 { 467 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg; 468 schedule_work(&rinfo->work); 469 } 470 471 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 472 { 473 /* We don't have real geometry info, but let's at least return 474 values consistent with the size of the device */ 475 sector_t nsect = get_capacity(bd->bd_disk); 476 sector_t cylinders = nsect; 477 478 hg->heads = 0xff; 479 hg->sectors = 0x3f; 480 sector_div(cylinders, hg->heads * hg->sectors); 481 hg->cylinders = cylinders; 482 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 483 hg->cylinders = 0xffff; 484 return 0; 485 } 486 487 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 488 unsigned command, unsigned long argument) 489 { 490 struct blkfront_info *info = bdev->bd_disk->private_data; 491 int i; 492 493 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 494 command, (long)argument); 495 496 switch (command) { 497 case CDROMMULTISESSION: 498 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 499 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 500 if (put_user(0, (char __user *)(argument + i))) 501 return -EFAULT; 502 return 0; 503 504 case CDROM_GET_CAPABILITY: { 505 struct gendisk *gd = info->gd; 506 if (gd->flags & GENHD_FL_CD) 507 return 0; 508 return -EINVAL; 509 } 510 511 default: 512 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 513 command);*/ 514 return -EINVAL; /* same return as native Linux */ 515 } 516 517 return 0; 518 } 519 520 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, 521 struct request *req, 522 struct blkif_request **ring_req) 523 { 524 unsigned long id; 525 526 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt); 527 rinfo->ring.req_prod_pvt++; 528 529 id = get_id_from_freelist(rinfo); 530 rinfo->shadow[id].request = req; 531 rinfo->shadow[id].status = REQ_WAITING; 532 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID; 533 534 (*ring_req)->u.rw.id = id; 535 536 return id; 537 } 538 539 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo) 540 { 541 struct blkfront_info *info = rinfo->dev_info; 542 struct blkif_request *ring_req; 543 unsigned long id; 544 545 /* Fill out a communications ring structure. */ 546 id = blkif_ring_get_request(rinfo, req, &ring_req); 547 548 ring_req->operation = BLKIF_OP_DISCARD; 549 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 550 ring_req->u.discard.id = id; 551 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 552 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard) 553 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 554 else 555 ring_req->u.discard.flag = 0; 556 557 /* Keep a private copy so we can reissue requests when recovering. */ 558 rinfo->shadow[id].req = *ring_req; 559 560 return 0; 561 } 562 563 struct setup_rw_req { 564 unsigned int grant_idx; 565 struct blkif_request_segment *segments; 566 struct blkfront_ring_info *rinfo; 567 struct blkif_request *ring_req; 568 grant_ref_t gref_head; 569 unsigned int id; 570 /* Only used when persistent grant is used and it's a read request */ 571 bool need_copy; 572 unsigned int bvec_off; 573 char *bvec_data; 574 575 bool require_extra_req; 576 struct blkif_request *extra_ring_req; 577 }; 578 579 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset, 580 unsigned int len, void *data) 581 { 582 struct setup_rw_req *setup = data; 583 int n, ref; 584 struct grant *gnt_list_entry; 585 unsigned int fsect, lsect; 586 /* Convenient aliases */ 587 unsigned int grant_idx = setup->grant_idx; 588 struct blkif_request *ring_req = setup->ring_req; 589 struct blkfront_ring_info *rinfo = setup->rinfo; 590 /* 591 * We always use the shadow of the first request to store the list 592 * of grant associated to the block I/O request. This made the 593 * completion more easy to handle even if the block I/O request is 594 * split. 595 */ 596 struct blk_shadow *shadow = &rinfo->shadow[setup->id]; 597 598 if (unlikely(setup->require_extra_req && 599 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 600 /* 601 * We are using the second request, setup grant_idx 602 * to be the index of the segment array. 603 */ 604 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST; 605 ring_req = setup->extra_ring_req; 606 } 607 608 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 609 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) { 610 if (setup->segments) 611 kunmap_atomic(setup->segments); 612 613 n = grant_idx / GRANTS_PER_INDIRECT_FRAME; 614 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo); 615 shadow->indirect_grants[n] = gnt_list_entry; 616 setup->segments = kmap_atomic(gnt_list_entry->page); 617 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 618 } 619 620 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo); 621 ref = gnt_list_entry->gref; 622 /* 623 * All the grants are stored in the shadow of the first 624 * request. Therefore we have to use the global index. 625 */ 626 shadow->grants_used[setup->grant_idx] = gnt_list_entry; 627 628 if (setup->need_copy) { 629 void *shared_data; 630 631 shared_data = kmap_atomic(gnt_list_entry->page); 632 /* 633 * this does not wipe data stored outside the 634 * range sg->offset..sg->offset+sg->length. 635 * Therefore, blkback *could* see data from 636 * previous requests. This is OK as long as 637 * persistent grants are shared with just one 638 * domain. It may need refactoring if this 639 * changes 640 */ 641 memcpy(shared_data + offset, 642 setup->bvec_data + setup->bvec_off, 643 len); 644 645 kunmap_atomic(shared_data); 646 setup->bvec_off += len; 647 } 648 649 fsect = offset >> 9; 650 lsect = fsect + (len >> 9) - 1; 651 if (ring_req->operation != BLKIF_OP_INDIRECT) { 652 ring_req->u.rw.seg[grant_idx] = 653 (struct blkif_request_segment) { 654 .gref = ref, 655 .first_sect = fsect, 656 .last_sect = lsect }; 657 } else { 658 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] = 659 (struct blkif_request_segment) { 660 .gref = ref, 661 .first_sect = fsect, 662 .last_sect = lsect }; 663 } 664 665 (setup->grant_idx)++; 666 } 667 668 static void blkif_setup_extra_req(struct blkif_request *first, 669 struct blkif_request *second) 670 { 671 uint16_t nr_segments = first->u.rw.nr_segments; 672 673 /* 674 * The second request is only present when the first request uses 675 * all its segments. It's always the continuity of the first one. 676 */ 677 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 678 679 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST; 680 second->u.rw.sector_number = first->u.rw.sector_number + 681 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512; 682 683 second->u.rw.handle = first->u.rw.handle; 684 second->operation = first->operation; 685 } 686 687 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo) 688 { 689 struct blkfront_info *info = rinfo->dev_info; 690 struct blkif_request *ring_req, *extra_ring_req = NULL; 691 unsigned long id, extra_id = NO_ASSOCIATED_ID; 692 bool require_extra_req = false; 693 int i; 694 struct setup_rw_req setup = { 695 .grant_idx = 0, 696 .segments = NULL, 697 .rinfo = rinfo, 698 .need_copy = rq_data_dir(req) && info->feature_persistent, 699 }; 700 701 /* 702 * Used to store if we are able to queue the request by just using 703 * existing persistent grants, or if we have to get new grants, 704 * as there are not sufficiently many free. 705 */ 706 bool new_persistent_gnts = false; 707 struct scatterlist *sg; 708 int num_sg, max_grefs, num_grant; 709 710 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG; 711 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 712 /* 713 * If we are using indirect segments we need to account 714 * for the indirect grefs used in the request. 715 */ 716 max_grefs += INDIRECT_GREFS(max_grefs); 717 718 /* Check if we have enough persistent grants to allocate a requests */ 719 if (rinfo->persistent_gnts_c < max_grefs) { 720 new_persistent_gnts = true; 721 722 if (gnttab_alloc_grant_references( 723 max_grefs - rinfo->persistent_gnts_c, 724 &setup.gref_head) < 0) { 725 gnttab_request_free_callback( 726 &rinfo->callback, 727 blkif_restart_queue_callback, 728 rinfo, 729 max_grefs - rinfo->persistent_gnts_c); 730 return 1; 731 } 732 } 733 734 /* Fill out a communications ring structure. */ 735 id = blkif_ring_get_request(rinfo, req, &ring_req); 736 737 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg); 738 num_grant = 0; 739 /* Calculate the number of grant used */ 740 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) 741 num_grant += gnttab_count_grant(sg->offset, sg->length); 742 743 require_extra_req = info->max_indirect_segments == 0 && 744 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST; 745 BUG_ON(!HAS_EXTRA_REQ && require_extra_req); 746 747 rinfo->shadow[id].num_sg = num_sg; 748 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST && 749 likely(!require_extra_req)) { 750 /* 751 * The indirect operation can only be a BLKIF_OP_READ or 752 * BLKIF_OP_WRITE 753 */ 754 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA); 755 ring_req->operation = BLKIF_OP_INDIRECT; 756 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 757 BLKIF_OP_WRITE : BLKIF_OP_READ; 758 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 759 ring_req->u.indirect.handle = info->handle; 760 ring_req->u.indirect.nr_segments = num_grant; 761 } else { 762 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 763 ring_req->u.rw.handle = info->handle; 764 ring_req->operation = rq_data_dir(req) ? 765 BLKIF_OP_WRITE : BLKIF_OP_READ; 766 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) { 767 /* 768 * Ideally we can do an unordered flush-to-disk. 769 * In case the backend onlysupports barriers, use that. 770 * A barrier request a superset of FUA, so we can 771 * implement it the same way. (It's also a FLUSH+FUA, 772 * since it is guaranteed ordered WRT previous writes.) 773 */ 774 if (info->feature_flush && info->feature_fua) 775 ring_req->operation = 776 BLKIF_OP_WRITE_BARRIER; 777 else if (info->feature_flush) 778 ring_req->operation = 779 BLKIF_OP_FLUSH_DISKCACHE; 780 else 781 ring_req->operation = 0; 782 } 783 ring_req->u.rw.nr_segments = num_grant; 784 if (unlikely(require_extra_req)) { 785 extra_id = blkif_ring_get_request(rinfo, req, 786 &extra_ring_req); 787 /* 788 * Only the first request contains the scatter-gather 789 * list. 790 */ 791 rinfo->shadow[extra_id].num_sg = 0; 792 793 blkif_setup_extra_req(ring_req, extra_ring_req); 794 795 /* Link the 2 requests together */ 796 rinfo->shadow[extra_id].associated_id = id; 797 rinfo->shadow[id].associated_id = extra_id; 798 } 799 } 800 801 setup.ring_req = ring_req; 802 setup.id = id; 803 804 setup.require_extra_req = require_extra_req; 805 if (unlikely(require_extra_req)) 806 setup.extra_ring_req = extra_ring_req; 807 808 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) { 809 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 810 811 if (setup.need_copy) { 812 setup.bvec_off = sg->offset; 813 setup.bvec_data = kmap_atomic(sg_page(sg)); 814 } 815 816 gnttab_foreach_grant_in_range(sg_page(sg), 817 sg->offset, 818 sg->length, 819 blkif_setup_rw_req_grant, 820 &setup); 821 822 if (setup.need_copy) 823 kunmap_atomic(setup.bvec_data); 824 } 825 if (setup.segments) 826 kunmap_atomic(setup.segments); 827 828 /* Keep a private copy so we can reissue requests when recovering. */ 829 rinfo->shadow[id].req = *ring_req; 830 if (unlikely(require_extra_req)) 831 rinfo->shadow[extra_id].req = *extra_ring_req; 832 833 if (new_persistent_gnts) 834 gnttab_free_grant_references(setup.gref_head); 835 836 return 0; 837 } 838 839 /* 840 * Generate a Xen blkfront IO request from a blk layer request. Reads 841 * and writes are handled as expected. 842 * 843 * @req: a request struct 844 */ 845 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo) 846 { 847 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED)) 848 return 1; 849 850 if (unlikely(req_op(req) == REQ_OP_DISCARD || 851 req_op(req) == REQ_OP_SECURE_ERASE)) 852 return blkif_queue_discard_req(req, rinfo); 853 else 854 return blkif_queue_rw_req(req, rinfo); 855 } 856 857 static inline void flush_requests(struct blkfront_ring_info *rinfo) 858 { 859 int notify; 860 861 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify); 862 863 if (notify) 864 notify_remote_via_irq(rinfo->irq); 865 } 866 867 static inline bool blkif_request_flush_invalid(struct request *req, 868 struct blkfront_info *info) 869 { 870 return (blk_rq_is_passthrough(req) || 871 ((req_op(req) == REQ_OP_FLUSH) && 872 !info->feature_flush) || 873 ((req->cmd_flags & REQ_FUA) && 874 !info->feature_fua)); 875 } 876 877 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx, 878 const struct blk_mq_queue_data *qd) 879 { 880 unsigned long flags; 881 int qid = hctx->queue_num; 882 struct blkfront_info *info = hctx->queue->queuedata; 883 struct blkfront_ring_info *rinfo = NULL; 884 885 BUG_ON(info->nr_rings <= qid); 886 rinfo = &info->rinfo[qid]; 887 blk_mq_start_request(qd->rq); 888 spin_lock_irqsave(&rinfo->ring_lock, flags); 889 if (RING_FULL(&rinfo->ring)) 890 goto out_busy; 891 892 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info)) 893 goto out_err; 894 895 if (blkif_queue_request(qd->rq, rinfo)) 896 goto out_busy; 897 898 flush_requests(rinfo); 899 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 900 return BLK_STS_OK; 901 902 out_err: 903 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 904 return BLK_STS_IOERR; 905 906 out_busy: 907 blk_mq_stop_hw_queue(hctx); 908 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 909 return BLK_STS_DEV_RESOURCE; 910 } 911 912 static void blkif_complete_rq(struct request *rq) 913 { 914 blk_mq_end_request(rq, blkif_req(rq)->error); 915 } 916 917 static const struct blk_mq_ops blkfront_mq_ops = { 918 .queue_rq = blkif_queue_rq, 919 .complete = blkif_complete_rq, 920 }; 921 922 static void blkif_set_queue_limits(struct blkfront_info *info) 923 { 924 struct request_queue *rq = info->rq; 925 struct gendisk *gd = info->gd; 926 unsigned int segments = info->max_indirect_segments ? : 927 BLKIF_MAX_SEGMENTS_PER_REQUEST; 928 929 blk_queue_flag_set(QUEUE_FLAG_VIRT, rq); 930 931 if (info->feature_discard) { 932 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq); 933 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 934 rq->limits.discard_granularity = info->discard_granularity; 935 rq->limits.discard_alignment = info->discard_alignment; 936 if (info->feature_secdiscard) 937 blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq); 938 } 939 940 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 941 blk_queue_logical_block_size(rq, info->sector_size); 942 blk_queue_physical_block_size(rq, info->physical_sector_size); 943 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512); 944 945 /* Each segment in a request is up to an aligned page in size. */ 946 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 947 blk_queue_max_segment_size(rq, PAGE_SIZE); 948 949 /* Ensure a merged request will fit in a single I/O ring slot. */ 950 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG); 951 952 /* Make sure buffer addresses are sector-aligned. */ 953 blk_queue_dma_alignment(rq, 511); 954 } 955 956 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, 957 unsigned int physical_sector_size) 958 { 959 struct request_queue *rq; 960 struct blkfront_info *info = gd->private_data; 961 962 memset(&info->tag_set, 0, sizeof(info->tag_set)); 963 info->tag_set.ops = &blkfront_mq_ops; 964 info->tag_set.nr_hw_queues = info->nr_rings; 965 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) { 966 /* 967 * When indirect descriptior is not supported, the I/O request 968 * will be split between multiple request in the ring. 969 * To avoid problems when sending the request, divide by 970 * 2 the depth of the queue. 971 */ 972 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2; 973 } else 974 info->tag_set.queue_depth = BLK_RING_SIZE(info); 975 info->tag_set.numa_node = NUMA_NO_NODE; 976 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; 977 info->tag_set.cmd_size = sizeof(struct blkif_req); 978 info->tag_set.driver_data = info; 979 980 if (blk_mq_alloc_tag_set(&info->tag_set)) 981 return -EINVAL; 982 rq = blk_mq_init_queue(&info->tag_set); 983 if (IS_ERR(rq)) { 984 blk_mq_free_tag_set(&info->tag_set); 985 return PTR_ERR(rq); 986 } 987 988 rq->queuedata = info; 989 info->rq = gd->queue = rq; 990 info->gd = gd; 991 info->sector_size = sector_size; 992 info->physical_sector_size = physical_sector_size; 993 blkif_set_queue_limits(info); 994 995 return 0; 996 } 997 998 static const char *flush_info(struct blkfront_info *info) 999 { 1000 if (info->feature_flush && info->feature_fua) 1001 return "barrier: enabled;"; 1002 else if (info->feature_flush) 1003 return "flush diskcache: enabled;"; 1004 else 1005 return "barrier or flush: disabled;"; 1006 } 1007 1008 static void xlvbd_flush(struct blkfront_info *info) 1009 { 1010 blk_queue_write_cache(info->rq, info->feature_flush ? true : false, 1011 info->feature_fua ? true : false); 1012 pr_info("blkfront: %s: %s %s %s %s %s\n", 1013 info->gd->disk_name, flush_info(info), 1014 "persistent grants:", info->feature_persistent ? 1015 "enabled;" : "disabled;", "indirect descriptors:", 1016 info->max_indirect_segments ? "enabled;" : "disabled;"); 1017 } 1018 1019 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 1020 { 1021 int major; 1022 major = BLKIF_MAJOR(vdevice); 1023 *minor = BLKIF_MINOR(vdevice); 1024 switch (major) { 1025 case XEN_IDE0_MAJOR: 1026 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 1027 *minor = ((*minor / 64) * PARTS_PER_DISK) + 1028 EMULATED_HD_DISK_MINOR_OFFSET; 1029 break; 1030 case XEN_IDE1_MAJOR: 1031 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 1032 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 1033 EMULATED_HD_DISK_MINOR_OFFSET; 1034 break; 1035 case XEN_SCSI_DISK0_MAJOR: 1036 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 1037 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 1038 break; 1039 case XEN_SCSI_DISK1_MAJOR: 1040 case XEN_SCSI_DISK2_MAJOR: 1041 case XEN_SCSI_DISK3_MAJOR: 1042 case XEN_SCSI_DISK4_MAJOR: 1043 case XEN_SCSI_DISK5_MAJOR: 1044 case XEN_SCSI_DISK6_MAJOR: 1045 case XEN_SCSI_DISK7_MAJOR: 1046 *offset = (*minor / PARTS_PER_DISK) + 1047 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 1048 EMULATED_SD_DISK_NAME_OFFSET; 1049 *minor = *minor + 1050 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 1051 EMULATED_SD_DISK_MINOR_OFFSET; 1052 break; 1053 case XEN_SCSI_DISK8_MAJOR: 1054 case XEN_SCSI_DISK9_MAJOR: 1055 case XEN_SCSI_DISK10_MAJOR: 1056 case XEN_SCSI_DISK11_MAJOR: 1057 case XEN_SCSI_DISK12_MAJOR: 1058 case XEN_SCSI_DISK13_MAJOR: 1059 case XEN_SCSI_DISK14_MAJOR: 1060 case XEN_SCSI_DISK15_MAJOR: 1061 *offset = (*minor / PARTS_PER_DISK) + 1062 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 1063 EMULATED_SD_DISK_NAME_OFFSET; 1064 *minor = *minor + 1065 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 1066 EMULATED_SD_DISK_MINOR_OFFSET; 1067 break; 1068 case XENVBD_MAJOR: 1069 *offset = *minor / PARTS_PER_DISK; 1070 break; 1071 default: 1072 printk(KERN_WARNING "blkfront: your disk configuration is " 1073 "incorrect, please use an xvd device instead\n"); 1074 return -ENODEV; 1075 } 1076 return 0; 1077 } 1078 1079 static char *encode_disk_name(char *ptr, unsigned int n) 1080 { 1081 if (n >= 26) 1082 ptr = encode_disk_name(ptr, n / 26 - 1); 1083 *ptr = 'a' + n % 26; 1084 return ptr + 1; 1085 } 1086 1087 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 1088 struct blkfront_info *info, 1089 u16 vdisk_info, u16 sector_size, 1090 unsigned int physical_sector_size) 1091 { 1092 struct gendisk *gd; 1093 int nr_minors = 1; 1094 int err; 1095 unsigned int offset; 1096 int minor; 1097 int nr_parts; 1098 char *ptr; 1099 1100 BUG_ON(info->gd != NULL); 1101 BUG_ON(info->rq != NULL); 1102 1103 if ((info->vdevice>>EXT_SHIFT) > 1) { 1104 /* this is above the extended range; something is wrong */ 1105 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 1106 return -ENODEV; 1107 } 1108 1109 if (!VDEV_IS_EXTENDED(info->vdevice)) { 1110 err = xen_translate_vdev(info->vdevice, &minor, &offset); 1111 if (err) 1112 return err; 1113 nr_parts = PARTS_PER_DISK; 1114 } else { 1115 minor = BLKIF_MINOR_EXT(info->vdevice); 1116 nr_parts = PARTS_PER_EXT_DISK; 1117 offset = minor / nr_parts; 1118 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 1119 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 1120 "emulated IDE disks,\n\t choose an xvd device name" 1121 "from xvde on\n", info->vdevice); 1122 } 1123 if (minor >> MINORBITS) { 1124 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 1125 info->vdevice, minor); 1126 return -ENODEV; 1127 } 1128 1129 if ((minor % nr_parts) == 0) 1130 nr_minors = nr_parts; 1131 1132 err = xlbd_reserve_minors(minor, nr_minors); 1133 if (err) 1134 goto out; 1135 err = -ENODEV; 1136 1137 gd = alloc_disk(nr_minors); 1138 if (gd == NULL) 1139 goto release; 1140 1141 strcpy(gd->disk_name, DEV_NAME); 1142 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 1143 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 1144 if (nr_minors > 1) 1145 *ptr = 0; 1146 else 1147 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 1148 "%d", minor & (nr_parts - 1)); 1149 1150 gd->major = XENVBD_MAJOR; 1151 gd->first_minor = minor; 1152 gd->fops = &xlvbd_block_fops; 1153 gd->private_data = info; 1154 set_capacity(gd, capacity); 1155 1156 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) { 1157 del_gendisk(gd); 1158 goto release; 1159 } 1160 1161 xlvbd_flush(info); 1162 1163 if (vdisk_info & VDISK_READONLY) 1164 set_disk_ro(gd, 1); 1165 1166 if (vdisk_info & VDISK_REMOVABLE) 1167 gd->flags |= GENHD_FL_REMOVABLE; 1168 1169 if (vdisk_info & VDISK_CDROM) 1170 gd->flags |= GENHD_FL_CD; 1171 1172 return 0; 1173 1174 release: 1175 xlbd_release_minors(minor, nr_minors); 1176 out: 1177 return err; 1178 } 1179 1180 static void xlvbd_release_gendisk(struct blkfront_info *info) 1181 { 1182 unsigned int minor, nr_minors, i; 1183 1184 if (info->rq == NULL) 1185 return; 1186 1187 /* No more blkif_request(). */ 1188 blk_mq_stop_hw_queues(info->rq); 1189 1190 for (i = 0; i < info->nr_rings; i++) { 1191 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1192 1193 /* No more gnttab callback work. */ 1194 gnttab_cancel_free_callback(&rinfo->callback); 1195 1196 /* Flush gnttab callback work. Must be done with no locks held. */ 1197 flush_work(&rinfo->work); 1198 } 1199 1200 del_gendisk(info->gd); 1201 1202 minor = info->gd->first_minor; 1203 nr_minors = info->gd->minors; 1204 xlbd_release_minors(minor, nr_minors); 1205 1206 blk_cleanup_queue(info->rq); 1207 blk_mq_free_tag_set(&info->tag_set); 1208 info->rq = NULL; 1209 1210 put_disk(info->gd); 1211 info->gd = NULL; 1212 } 1213 1214 /* Already hold rinfo->ring_lock. */ 1215 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo) 1216 { 1217 if (!RING_FULL(&rinfo->ring)) 1218 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true); 1219 } 1220 1221 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo) 1222 { 1223 unsigned long flags; 1224 1225 spin_lock_irqsave(&rinfo->ring_lock, flags); 1226 kick_pending_request_queues_locked(rinfo); 1227 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1228 } 1229 1230 static void blkif_restart_queue(struct work_struct *work) 1231 { 1232 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work); 1233 1234 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED) 1235 kick_pending_request_queues(rinfo); 1236 } 1237 1238 static void blkif_free_ring(struct blkfront_ring_info *rinfo) 1239 { 1240 struct grant *persistent_gnt, *n; 1241 struct blkfront_info *info = rinfo->dev_info; 1242 int i, j, segs; 1243 1244 /* 1245 * Remove indirect pages, this only happens when using indirect 1246 * descriptors but not persistent grants 1247 */ 1248 if (!list_empty(&rinfo->indirect_pages)) { 1249 struct page *indirect_page, *n; 1250 1251 BUG_ON(info->feature_persistent); 1252 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 1253 list_del(&indirect_page->lru); 1254 __free_page(indirect_page); 1255 } 1256 } 1257 1258 /* Remove all persistent grants. */ 1259 if (!list_empty(&rinfo->grants)) { 1260 list_for_each_entry_safe(persistent_gnt, n, 1261 &rinfo->grants, node) { 1262 list_del(&persistent_gnt->node); 1263 if (persistent_gnt->gref != GRANT_INVALID_REF) { 1264 gnttab_end_foreign_access(persistent_gnt->gref, 1265 0, 0UL); 1266 rinfo->persistent_gnts_c--; 1267 } 1268 if (info->feature_persistent) 1269 __free_page(persistent_gnt->page); 1270 kfree(persistent_gnt); 1271 } 1272 } 1273 BUG_ON(rinfo->persistent_gnts_c != 0); 1274 1275 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1276 /* 1277 * Clear persistent grants present in requests already 1278 * on the shared ring 1279 */ 1280 if (!rinfo->shadow[i].request) 1281 goto free_shadow; 1282 1283 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 1284 rinfo->shadow[i].req.u.indirect.nr_segments : 1285 rinfo->shadow[i].req.u.rw.nr_segments; 1286 for (j = 0; j < segs; j++) { 1287 persistent_gnt = rinfo->shadow[i].grants_used[j]; 1288 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1289 if (info->feature_persistent) 1290 __free_page(persistent_gnt->page); 1291 kfree(persistent_gnt); 1292 } 1293 1294 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT) 1295 /* 1296 * If this is not an indirect operation don't try to 1297 * free indirect segments 1298 */ 1299 goto free_shadow; 1300 1301 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 1302 persistent_gnt = rinfo->shadow[i].indirect_grants[j]; 1303 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1304 __free_page(persistent_gnt->page); 1305 kfree(persistent_gnt); 1306 } 1307 1308 free_shadow: 1309 kfree(rinfo->shadow[i].grants_used); 1310 rinfo->shadow[i].grants_used = NULL; 1311 kfree(rinfo->shadow[i].indirect_grants); 1312 rinfo->shadow[i].indirect_grants = NULL; 1313 kfree(rinfo->shadow[i].sg); 1314 rinfo->shadow[i].sg = NULL; 1315 } 1316 1317 /* No more gnttab callback work. */ 1318 gnttab_cancel_free_callback(&rinfo->callback); 1319 1320 /* Flush gnttab callback work. Must be done with no locks held. */ 1321 flush_work(&rinfo->work); 1322 1323 /* Free resources associated with old device channel. */ 1324 for (i = 0; i < info->nr_ring_pages; i++) { 1325 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) { 1326 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0); 1327 rinfo->ring_ref[i] = GRANT_INVALID_REF; 1328 } 1329 } 1330 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE)); 1331 rinfo->ring.sring = NULL; 1332 1333 if (rinfo->irq) 1334 unbind_from_irqhandler(rinfo->irq, rinfo); 1335 rinfo->evtchn = rinfo->irq = 0; 1336 } 1337 1338 static void blkif_free(struct blkfront_info *info, int suspend) 1339 { 1340 unsigned int i; 1341 1342 /* Prevent new requests being issued until we fix things up. */ 1343 info->connected = suspend ? 1344 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 1345 /* No more blkif_request(). */ 1346 if (info->rq) 1347 blk_mq_stop_hw_queues(info->rq); 1348 1349 for (i = 0; i < info->nr_rings; i++) 1350 blkif_free_ring(&info->rinfo[i]); 1351 1352 kfree(info->rinfo); 1353 info->rinfo = NULL; 1354 info->nr_rings = 0; 1355 } 1356 1357 struct copy_from_grant { 1358 const struct blk_shadow *s; 1359 unsigned int grant_idx; 1360 unsigned int bvec_offset; 1361 char *bvec_data; 1362 }; 1363 1364 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset, 1365 unsigned int len, void *data) 1366 { 1367 struct copy_from_grant *info = data; 1368 char *shared_data; 1369 /* Convenient aliases */ 1370 const struct blk_shadow *s = info->s; 1371 1372 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page); 1373 1374 memcpy(info->bvec_data + info->bvec_offset, 1375 shared_data + offset, len); 1376 1377 info->bvec_offset += len; 1378 info->grant_idx++; 1379 1380 kunmap_atomic(shared_data); 1381 } 1382 1383 static enum blk_req_status blkif_rsp_to_req_status(int rsp) 1384 { 1385 switch (rsp) 1386 { 1387 case BLKIF_RSP_OKAY: 1388 return REQ_DONE; 1389 case BLKIF_RSP_EOPNOTSUPP: 1390 return REQ_EOPNOTSUPP; 1391 case BLKIF_RSP_ERROR: 1392 /* Fallthrough. */ 1393 default: 1394 return REQ_ERROR; 1395 } 1396 } 1397 1398 /* 1399 * Get the final status of the block request based on two ring response 1400 */ 1401 static int blkif_get_final_status(enum blk_req_status s1, 1402 enum blk_req_status s2) 1403 { 1404 BUG_ON(s1 == REQ_WAITING); 1405 BUG_ON(s2 == REQ_WAITING); 1406 1407 if (s1 == REQ_ERROR || s2 == REQ_ERROR) 1408 return BLKIF_RSP_ERROR; 1409 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP) 1410 return BLKIF_RSP_EOPNOTSUPP; 1411 return BLKIF_RSP_OKAY; 1412 } 1413 1414 static bool blkif_completion(unsigned long *id, 1415 struct blkfront_ring_info *rinfo, 1416 struct blkif_response *bret) 1417 { 1418 int i = 0; 1419 struct scatterlist *sg; 1420 int num_sg, num_grant; 1421 struct blkfront_info *info = rinfo->dev_info; 1422 struct blk_shadow *s = &rinfo->shadow[*id]; 1423 struct copy_from_grant data = { 1424 .grant_idx = 0, 1425 }; 1426 1427 num_grant = s->req.operation == BLKIF_OP_INDIRECT ? 1428 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1429 1430 /* The I/O request may be split in two. */ 1431 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) { 1432 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id]; 1433 1434 /* Keep the status of the current response in shadow. */ 1435 s->status = blkif_rsp_to_req_status(bret->status); 1436 1437 /* Wait the second response if not yet here. */ 1438 if (s2->status == REQ_WAITING) 1439 return false; 1440 1441 bret->status = blkif_get_final_status(s->status, 1442 s2->status); 1443 1444 /* 1445 * All the grants is stored in the first shadow in order 1446 * to make the completion code simpler. 1447 */ 1448 num_grant += s2->req.u.rw.nr_segments; 1449 1450 /* 1451 * The two responses may not come in order. Only the 1452 * first request will store the scatter-gather list. 1453 */ 1454 if (s2->num_sg != 0) { 1455 /* Update "id" with the ID of the first response. */ 1456 *id = s->associated_id; 1457 s = s2; 1458 } 1459 1460 /* 1461 * We don't need anymore the second request, so recycling 1462 * it now. 1463 */ 1464 if (add_id_to_freelist(rinfo, s->associated_id)) 1465 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n", 1466 info->gd->disk_name, s->associated_id); 1467 } 1468 1469 data.s = s; 1470 num_sg = s->num_sg; 1471 1472 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { 1473 for_each_sg(s->sg, sg, num_sg, i) { 1474 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1475 1476 data.bvec_offset = sg->offset; 1477 data.bvec_data = kmap_atomic(sg_page(sg)); 1478 1479 gnttab_foreach_grant_in_range(sg_page(sg), 1480 sg->offset, 1481 sg->length, 1482 blkif_copy_from_grant, 1483 &data); 1484 1485 kunmap_atomic(data.bvec_data); 1486 } 1487 } 1488 /* Add the persistent grant into the list of free grants */ 1489 for (i = 0; i < num_grant; i++) { 1490 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) { 1491 /* 1492 * If the grant is still mapped by the backend (the 1493 * backend has chosen to make this grant persistent) 1494 * we add it at the head of the list, so it will be 1495 * reused first. 1496 */ 1497 if (!info->feature_persistent) 1498 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1499 s->grants_used[i]->gref); 1500 list_add(&s->grants_used[i]->node, &rinfo->grants); 1501 rinfo->persistent_gnts_c++; 1502 } else { 1503 /* 1504 * If the grant is not mapped by the backend we end the 1505 * foreign access and add it to the tail of the list, 1506 * so it will not be picked again unless we run out of 1507 * persistent grants. 1508 */ 1509 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); 1510 s->grants_used[i]->gref = GRANT_INVALID_REF; 1511 list_add_tail(&s->grants_used[i]->node, &rinfo->grants); 1512 } 1513 } 1514 if (s->req.operation == BLKIF_OP_INDIRECT) { 1515 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) { 1516 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { 1517 if (!info->feature_persistent) 1518 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1519 s->indirect_grants[i]->gref); 1520 list_add(&s->indirect_grants[i]->node, &rinfo->grants); 1521 rinfo->persistent_gnts_c++; 1522 } else { 1523 struct page *indirect_page; 1524 1525 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); 1526 /* 1527 * Add the used indirect page back to the list of 1528 * available pages for indirect grefs. 1529 */ 1530 if (!info->feature_persistent) { 1531 indirect_page = s->indirect_grants[i]->page; 1532 list_add(&indirect_page->lru, &rinfo->indirect_pages); 1533 } 1534 s->indirect_grants[i]->gref = GRANT_INVALID_REF; 1535 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants); 1536 } 1537 } 1538 } 1539 1540 return true; 1541 } 1542 1543 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1544 { 1545 struct request *req; 1546 struct blkif_response *bret; 1547 RING_IDX i, rp; 1548 unsigned long flags; 1549 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id; 1550 struct blkfront_info *info = rinfo->dev_info; 1551 1552 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 1553 return IRQ_HANDLED; 1554 1555 spin_lock_irqsave(&rinfo->ring_lock, flags); 1556 again: 1557 rp = rinfo->ring.sring->rsp_prod; 1558 rmb(); /* Ensure we see queued responses up to 'rp'. */ 1559 1560 for (i = rinfo->ring.rsp_cons; i != rp; i++) { 1561 unsigned long id; 1562 1563 bret = RING_GET_RESPONSE(&rinfo->ring, i); 1564 id = bret->id; 1565 /* 1566 * The backend has messed up and given us an id that we would 1567 * never have given to it (we stamp it up to BLK_RING_SIZE - 1568 * look in get_id_from_freelist. 1569 */ 1570 if (id >= BLK_RING_SIZE(info)) { 1571 WARN(1, "%s: response to %s has incorrect id (%ld)\n", 1572 info->gd->disk_name, op_name(bret->operation), id); 1573 /* We can't safely get the 'struct request' as 1574 * the id is busted. */ 1575 continue; 1576 } 1577 req = rinfo->shadow[id].request; 1578 1579 if (bret->operation != BLKIF_OP_DISCARD) { 1580 /* 1581 * We may need to wait for an extra response if the 1582 * I/O request is split in 2 1583 */ 1584 if (!blkif_completion(&id, rinfo, bret)) 1585 continue; 1586 } 1587 1588 if (add_id_to_freelist(rinfo, id)) { 1589 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1590 info->gd->disk_name, op_name(bret->operation), id); 1591 continue; 1592 } 1593 1594 if (bret->status == BLKIF_RSP_OKAY) 1595 blkif_req(req)->error = BLK_STS_OK; 1596 else 1597 blkif_req(req)->error = BLK_STS_IOERR; 1598 1599 switch (bret->operation) { 1600 case BLKIF_OP_DISCARD: 1601 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1602 struct request_queue *rq = info->rq; 1603 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1604 info->gd->disk_name, op_name(bret->operation)); 1605 blkif_req(req)->error = BLK_STS_NOTSUPP; 1606 info->feature_discard = 0; 1607 info->feature_secdiscard = 0; 1608 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 1609 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq); 1610 } 1611 break; 1612 case BLKIF_OP_FLUSH_DISKCACHE: 1613 case BLKIF_OP_WRITE_BARRIER: 1614 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1615 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1616 info->gd->disk_name, op_name(bret->operation)); 1617 blkif_req(req)->error = BLK_STS_NOTSUPP; 1618 } 1619 if (unlikely(bret->status == BLKIF_RSP_ERROR && 1620 rinfo->shadow[id].req.u.rw.nr_segments == 0)) { 1621 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", 1622 info->gd->disk_name, op_name(bret->operation)); 1623 blkif_req(req)->error = BLK_STS_NOTSUPP; 1624 } 1625 if (unlikely(blkif_req(req)->error)) { 1626 if (blkif_req(req)->error == BLK_STS_NOTSUPP) 1627 blkif_req(req)->error = BLK_STS_OK; 1628 info->feature_fua = 0; 1629 info->feature_flush = 0; 1630 xlvbd_flush(info); 1631 } 1632 /* fall through */ 1633 case BLKIF_OP_READ: 1634 case BLKIF_OP_WRITE: 1635 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 1636 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 1637 "request: %x\n", bret->status); 1638 1639 break; 1640 default: 1641 BUG(); 1642 } 1643 1644 blk_mq_complete_request(req); 1645 } 1646 1647 rinfo->ring.rsp_cons = i; 1648 1649 if (i != rinfo->ring.req_prod_pvt) { 1650 int more_to_do; 1651 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do); 1652 if (more_to_do) 1653 goto again; 1654 } else 1655 rinfo->ring.sring->rsp_event = i + 1; 1656 1657 kick_pending_request_queues_locked(rinfo); 1658 1659 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1660 1661 return IRQ_HANDLED; 1662 } 1663 1664 1665 static int setup_blkring(struct xenbus_device *dev, 1666 struct blkfront_ring_info *rinfo) 1667 { 1668 struct blkif_sring *sring; 1669 int err, i; 1670 struct blkfront_info *info = rinfo->dev_info; 1671 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE; 1672 grant_ref_t gref[XENBUS_MAX_RING_GRANTS]; 1673 1674 for (i = 0; i < info->nr_ring_pages; i++) 1675 rinfo->ring_ref[i] = GRANT_INVALID_REF; 1676 1677 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH, 1678 get_order(ring_size)); 1679 if (!sring) { 1680 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1681 return -ENOMEM; 1682 } 1683 SHARED_RING_INIT(sring); 1684 FRONT_RING_INIT(&rinfo->ring, sring, ring_size); 1685 1686 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref); 1687 if (err < 0) { 1688 free_pages((unsigned long)sring, get_order(ring_size)); 1689 rinfo->ring.sring = NULL; 1690 goto fail; 1691 } 1692 for (i = 0; i < info->nr_ring_pages; i++) 1693 rinfo->ring_ref[i] = gref[i]; 1694 1695 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn); 1696 if (err) 1697 goto fail; 1698 1699 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0, 1700 "blkif", rinfo); 1701 if (err <= 0) { 1702 xenbus_dev_fatal(dev, err, 1703 "bind_evtchn_to_irqhandler failed"); 1704 goto fail; 1705 } 1706 rinfo->irq = err; 1707 1708 return 0; 1709 fail: 1710 blkif_free(info, 0); 1711 return err; 1712 } 1713 1714 /* 1715 * Write out per-ring/queue nodes including ring-ref and event-channel, and each 1716 * ring buffer may have multi pages depending on ->nr_ring_pages. 1717 */ 1718 static int write_per_ring_nodes(struct xenbus_transaction xbt, 1719 struct blkfront_ring_info *rinfo, const char *dir) 1720 { 1721 int err; 1722 unsigned int i; 1723 const char *message = NULL; 1724 struct blkfront_info *info = rinfo->dev_info; 1725 1726 if (info->nr_ring_pages == 1) { 1727 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]); 1728 if (err) { 1729 message = "writing ring-ref"; 1730 goto abort_transaction; 1731 } 1732 } else { 1733 for (i = 0; i < info->nr_ring_pages; i++) { 1734 char ring_ref_name[RINGREF_NAME_LEN]; 1735 1736 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 1737 err = xenbus_printf(xbt, dir, ring_ref_name, 1738 "%u", rinfo->ring_ref[i]); 1739 if (err) { 1740 message = "writing ring-ref"; 1741 goto abort_transaction; 1742 } 1743 } 1744 } 1745 1746 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn); 1747 if (err) { 1748 message = "writing event-channel"; 1749 goto abort_transaction; 1750 } 1751 1752 return 0; 1753 1754 abort_transaction: 1755 xenbus_transaction_end(xbt, 1); 1756 if (message) 1757 xenbus_dev_fatal(info->xbdev, err, "%s", message); 1758 1759 return err; 1760 } 1761 1762 /* Common code used when first setting up, and when resuming. */ 1763 static int talk_to_blkback(struct xenbus_device *dev, 1764 struct blkfront_info *info) 1765 { 1766 const char *message = NULL; 1767 struct xenbus_transaction xbt; 1768 int err; 1769 unsigned int i, max_page_order; 1770 unsigned int ring_page_order; 1771 1772 if (!info) 1773 return -ENODEV; 1774 1775 max_page_order = xenbus_read_unsigned(info->xbdev->otherend, 1776 "max-ring-page-order", 0); 1777 ring_page_order = min(xen_blkif_max_ring_order, max_page_order); 1778 info->nr_ring_pages = 1 << ring_page_order; 1779 1780 err = negotiate_mq(info); 1781 if (err) 1782 goto destroy_blkring; 1783 1784 for (i = 0; i < info->nr_rings; i++) { 1785 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1786 1787 /* Create shared ring, alloc event channel. */ 1788 err = setup_blkring(dev, rinfo); 1789 if (err) 1790 goto destroy_blkring; 1791 } 1792 1793 again: 1794 err = xenbus_transaction_start(&xbt); 1795 if (err) { 1796 xenbus_dev_fatal(dev, err, "starting transaction"); 1797 goto destroy_blkring; 1798 } 1799 1800 if (info->nr_ring_pages > 1) { 1801 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u", 1802 ring_page_order); 1803 if (err) { 1804 message = "writing ring-page-order"; 1805 goto abort_transaction; 1806 } 1807 } 1808 1809 /* We already got the number of queues/rings in _probe */ 1810 if (info->nr_rings == 1) { 1811 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename); 1812 if (err) 1813 goto destroy_blkring; 1814 } else { 1815 char *path; 1816 size_t pathsize; 1817 1818 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u", 1819 info->nr_rings); 1820 if (err) { 1821 message = "writing multi-queue-num-queues"; 1822 goto abort_transaction; 1823 } 1824 1825 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN; 1826 path = kmalloc(pathsize, GFP_KERNEL); 1827 if (!path) { 1828 err = -ENOMEM; 1829 message = "ENOMEM while writing ring references"; 1830 goto abort_transaction; 1831 } 1832 1833 for (i = 0; i < info->nr_rings; i++) { 1834 memset(path, 0, pathsize); 1835 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i); 1836 err = write_per_ring_nodes(xbt, &info->rinfo[i], path); 1837 if (err) { 1838 kfree(path); 1839 goto destroy_blkring; 1840 } 1841 } 1842 kfree(path); 1843 } 1844 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1845 XEN_IO_PROTO_ABI_NATIVE); 1846 if (err) { 1847 message = "writing protocol"; 1848 goto abort_transaction; 1849 } 1850 err = xenbus_printf(xbt, dev->nodename, 1851 "feature-persistent", "%u", 1); 1852 if (err) 1853 dev_warn(&dev->dev, 1854 "writing persistent grants feature to xenbus"); 1855 1856 err = xenbus_transaction_end(xbt, 0); 1857 if (err) { 1858 if (err == -EAGAIN) 1859 goto again; 1860 xenbus_dev_fatal(dev, err, "completing transaction"); 1861 goto destroy_blkring; 1862 } 1863 1864 for (i = 0; i < info->nr_rings; i++) { 1865 unsigned int j; 1866 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1867 1868 for (j = 0; j < BLK_RING_SIZE(info); j++) 1869 rinfo->shadow[j].req.u.rw.id = j + 1; 1870 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 1871 } 1872 xenbus_switch_state(dev, XenbusStateInitialised); 1873 1874 return 0; 1875 1876 abort_transaction: 1877 xenbus_transaction_end(xbt, 1); 1878 if (message) 1879 xenbus_dev_fatal(dev, err, "%s", message); 1880 destroy_blkring: 1881 blkif_free(info, 0); 1882 1883 kfree(info); 1884 dev_set_drvdata(&dev->dev, NULL); 1885 1886 return err; 1887 } 1888 1889 static int negotiate_mq(struct blkfront_info *info) 1890 { 1891 unsigned int backend_max_queues; 1892 unsigned int i; 1893 1894 BUG_ON(info->nr_rings); 1895 1896 /* Check if backend supports multiple queues. */ 1897 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend, 1898 "multi-queue-max-queues", 1); 1899 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues); 1900 /* We need at least one ring. */ 1901 if (!info->nr_rings) 1902 info->nr_rings = 1; 1903 1904 info->rinfo = kcalloc(info->nr_rings, 1905 sizeof(struct blkfront_ring_info), 1906 GFP_KERNEL); 1907 if (!info->rinfo) { 1908 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure"); 1909 return -ENOMEM; 1910 } 1911 1912 for (i = 0; i < info->nr_rings; i++) { 1913 struct blkfront_ring_info *rinfo; 1914 1915 rinfo = &info->rinfo[i]; 1916 INIT_LIST_HEAD(&rinfo->indirect_pages); 1917 INIT_LIST_HEAD(&rinfo->grants); 1918 rinfo->dev_info = info; 1919 INIT_WORK(&rinfo->work, blkif_restart_queue); 1920 spin_lock_init(&rinfo->ring_lock); 1921 } 1922 return 0; 1923 } 1924 /** 1925 * Entry point to this code when a new device is created. Allocate the basic 1926 * structures and the ring buffer for communication with the backend, and 1927 * inform the backend of the appropriate details for those. Switch to 1928 * Initialised state. 1929 */ 1930 static int blkfront_probe(struct xenbus_device *dev, 1931 const struct xenbus_device_id *id) 1932 { 1933 int err, vdevice; 1934 struct blkfront_info *info; 1935 1936 /* FIXME: Use dynamic device id if this is not set. */ 1937 err = xenbus_scanf(XBT_NIL, dev->nodename, 1938 "virtual-device", "%i", &vdevice); 1939 if (err != 1) { 1940 /* go looking in the extended area instead */ 1941 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1942 "%i", &vdevice); 1943 if (err != 1) { 1944 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1945 return err; 1946 } 1947 } 1948 1949 if (xen_hvm_domain()) { 1950 char *type; 1951 int len; 1952 /* no unplug has been done: do not hook devices != xen vbds */ 1953 if (xen_has_pv_and_legacy_disk_devices()) { 1954 int major; 1955 1956 if (!VDEV_IS_EXTENDED(vdevice)) 1957 major = BLKIF_MAJOR(vdevice); 1958 else 1959 major = XENVBD_MAJOR; 1960 1961 if (major != XENVBD_MAJOR) { 1962 printk(KERN_INFO 1963 "%s: HVM does not support vbd %d as xen block device\n", 1964 __func__, vdevice); 1965 return -ENODEV; 1966 } 1967 } 1968 /* do not create a PV cdrom device if we are an HVM guest */ 1969 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1970 if (IS_ERR(type)) 1971 return -ENODEV; 1972 if (strncmp(type, "cdrom", 5) == 0) { 1973 kfree(type); 1974 return -ENODEV; 1975 } 1976 kfree(type); 1977 } 1978 info = kzalloc(sizeof(*info), GFP_KERNEL); 1979 if (!info) { 1980 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1981 return -ENOMEM; 1982 } 1983 1984 info->xbdev = dev; 1985 1986 mutex_init(&info->mutex); 1987 info->vdevice = vdevice; 1988 info->connected = BLKIF_STATE_DISCONNECTED; 1989 1990 /* Front end dir is a number, which is used as the id. */ 1991 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1992 dev_set_drvdata(&dev->dev, info); 1993 1994 return 0; 1995 } 1996 1997 static int blkif_recover(struct blkfront_info *info) 1998 { 1999 unsigned int r_index; 2000 struct request *req, *n; 2001 int rc; 2002 struct bio *bio; 2003 unsigned int segs; 2004 2005 blkfront_gather_backend_features(info); 2006 /* Reset limits changed by blk_mq_update_nr_hw_queues(). */ 2007 blkif_set_queue_limits(info); 2008 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 2009 blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG); 2010 2011 for (r_index = 0; r_index < info->nr_rings; r_index++) { 2012 struct blkfront_ring_info *rinfo = &info->rinfo[r_index]; 2013 2014 rc = blkfront_setup_indirect(rinfo); 2015 if (rc) 2016 return rc; 2017 } 2018 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2019 2020 /* Now safe for us to use the shared ring */ 2021 info->connected = BLKIF_STATE_CONNECTED; 2022 2023 for (r_index = 0; r_index < info->nr_rings; r_index++) { 2024 struct blkfront_ring_info *rinfo; 2025 2026 rinfo = &info->rinfo[r_index]; 2027 /* Kick any other new requests queued since we resumed */ 2028 kick_pending_request_queues(rinfo); 2029 } 2030 2031 list_for_each_entry_safe(req, n, &info->requests, queuelist) { 2032 /* Requeue pending requests (flush or discard) */ 2033 list_del_init(&req->queuelist); 2034 BUG_ON(req->nr_phys_segments > segs); 2035 blk_mq_requeue_request(req, false); 2036 } 2037 blk_mq_start_stopped_hw_queues(info->rq, true); 2038 blk_mq_kick_requeue_list(info->rq); 2039 2040 while ((bio = bio_list_pop(&info->bio_list)) != NULL) { 2041 /* Traverse the list of pending bios and re-queue them */ 2042 submit_bio(bio); 2043 } 2044 2045 return 0; 2046 } 2047 2048 /** 2049 * We are reconnecting to the backend, due to a suspend/resume, or a backend 2050 * driver restart. We tear down our blkif structure and recreate it, but 2051 * leave the device-layer structures intact so that this is transparent to the 2052 * rest of the kernel. 2053 */ 2054 static int blkfront_resume(struct xenbus_device *dev) 2055 { 2056 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2057 int err = 0; 2058 unsigned int i, j; 2059 2060 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 2061 2062 bio_list_init(&info->bio_list); 2063 INIT_LIST_HEAD(&info->requests); 2064 for (i = 0; i < info->nr_rings; i++) { 2065 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 2066 struct bio_list merge_bio; 2067 struct blk_shadow *shadow = rinfo->shadow; 2068 2069 for (j = 0; j < BLK_RING_SIZE(info); j++) { 2070 /* Not in use? */ 2071 if (!shadow[j].request) 2072 continue; 2073 2074 /* 2075 * Get the bios in the request so we can re-queue them. 2076 */ 2077 if (req_op(shadow[j].request) == REQ_OP_FLUSH || 2078 req_op(shadow[j].request) == REQ_OP_DISCARD || 2079 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE || 2080 shadow[j].request->cmd_flags & REQ_FUA) { 2081 /* 2082 * Flush operations don't contain bios, so 2083 * we need to requeue the whole request 2084 * 2085 * XXX: but this doesn't make any sense for a 2086 * write with the FUA flag set.. 2087 */ 2088 list_add(&shadow[j].request->queuelist, &info->requests); 2089 continue; 2090 } 2091 merge_bio.head = shadow[j].request->bio; 2092 merge_bio.tail = shadow[j].request->biotail; 2093 bio_list_merge(&info->bio_list, &merge_bio); 2094 shadow[j].request->bio = NULL; 2095 blk_mq_end_request(shadow[j].request, BLK_STS_OK); 2096 } 2097 } 2098 2099 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 2100 2101 err = talk_to_blkback(dev, info); 2102 if (!err) 2103 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings); 2104 2105 /* 2106 * We have to wait for the backend to switch to 2107 * connected state, since we want to read which 2108 * features it supports. 2109 */ 2110 2111 return err; 2112 } 2113 2114 static void blkfront_closing(struct blkfront_info *info) 2115 { 2116 struct xenbus_device *xbdev = info->xbdev; 2117 struct block_device *bdev = NULL; 2118 2119 mutex_lock(&info->mutex); 2120 2121 if (xbdev->state == XenbusStateClosing) { 2122 mutex_unlock(&info->mutex); 2123 return; 2124 } 2125 2126 if (info->gd) 2127 bdev = bdget_disk(info->gd, 0); 2128 2129 mutex_unlock(&info->mutex); 2130 2131 if (!bdev) { 2132 xenbus_frontend_closed(xbdev); 2133 return; 2134 } 2135 2136 mutex_lock(&bdev->bd_mutex); 2137 2138 if (bdev->bd_openers) { 2139 xenbus_dev_error(xbdev, -EBUSY, 2140 "Device in use; refusing to close"); 2141 xenbus_switch_state(xbdev, XenbusStateClosing); 2142 } else { 2143 xlvbd_release_gendisk(info); 2144 xenbus_frontend_closed(xbdev); 2145 } 2146 2147 mutex_unlock(&bdev->bd_mutex); 2148 bdput(bdev); 2149 } 2150 2151 static void blkfront_setup_discard(struct blkfront_info *info) 2152 { 2153 int err; 2154 unsigned int discard_granularity; 2155 unsigned int discard_alignment; 2156 2157 info->feature_discard = 1; 2158 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2159 "discard-granularity", "%u", &discard_granularity, 2160 "discard-alignment", "%u", &discard_alignment, 2161 NULL); 2162 if (!err) { 2163 info->discard_granularity = discard_granularity; 2164 info->discard_alignment = discard_alignment; 2165 } 2166 info->feature_secdiscard = 2167 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure", 2168 0); 2169 } 2170 2171 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo) 2172 { 2173 unsigned int psegs, grants; 2174 int err, i; 2175 struct blkfront_info *info = rinfo->dev_info; 2176 2177 if (info->max_indirect_segments == 0) { 2178 if (!HAS_EXTRA_REQ) 2179 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2180 else { 2181 /* 2182 * When an extra req is required, the maximum 2183 * grants supported is related to the size of the 2184 * Linux block segment. 2185 */ 2186 grants = GRANTS_PER_PSEG; 2187 } 2188 } 2189 else 2190 grants = info->max_indirect_segments; 2191 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG); 2192 2193 err = fill_grant_buffer(rinfo, 2194 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info)); 2195 if (err) 2196 goto out_of_memory; 2197 2198 if (!info->feature_persistent && info->max_indirect_segments) { 2199 /* 2200 * We are using indirect descriptors but not persistent 2201 * grants, we need to allocate a set of pages that can be 2202 * used for mapping indirect grefs 2203 */ 2204 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info); 2205 2206 BUG_ON(!list_empty(&rinfo->indirect_pages)); 2207 for (i = 0; i < num; i++) { 2208 struct page *indirect_page = alloc_page(GFP_NOIO); 2209 if (!indirect_page) 2210 goto out_of_memory; 2211 list_add(&indirect_page->lru, &rinfo->indirect_pages); 2212 } 2213 } 2214 2215 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2216 rinfo->shadow[i].grants_used = 2217 kcalloc(grants, 2218 sizeof(rinfo->shadow[i].grants_used[0]), 2219 GFP_NOIO); 2220 rinfo->shadow[i].sg = kcalloc(psegs, 2221 sizeof(rinfo->shadow[i].sg[0]), 2222 GFP_NOIO); 2223 if (info->max_indirect_segments) 2224 rinfo->shadow[i].indirect_grants = 2225 kcalloc(INDIRECT_GREFS(grants), 2226 sizeof(rinfo->shadow[i].indirect_grants[0]), 2227 GFP_NOIO); 2228 if ((rinfo->shadow[i].grants_used == NULL) || 2229 (rinfo->shadow[i].sg == NULL) || 2230 (info->max_indirect_segments && 2231 (rinfo->shadow[i].indirect_grants == NULL))) 2232 goto out_of_memory; 2233 sg_init_table(rinfo->shadow[i].sg, psegs); 2234 } 2235 2236 2237 return 0; 2238 2239 out_of_memory: 2240 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2241 kfree(rinfo->shadow[i].grants_used); 2242 rinfo->shadow[i].grants_used = NULL; 2243 kfree(rinfo->shadow[i].sg); 2244 rinfo->shadow[i].sg = NULL; 2245 kfree(rinfo->shadow[i].indirect_grants); 2246 rinfo->shadow[i].indirect_grants = NULL; 2247 } 2248 if (!list_empty(&rinfo->indirect_pages)) { 2249 struct page *indirect_page, *n; 2250 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 2251 list_del(&indirect_page->lru); 2252 __free_page(indirect_page); 2253 } 2254 } 2255 return -ENOMEM; 2256 } 2257 2258 /* 2259 * Gather all backend feature-* 2260 */ 2261 static void blkfront_gather_backend_features(struct blkfront_info *info) 2262 { 2263 unsigned int indirect_segments; 2264 2265 info->feature_flush = 0; 2266 info->feature_fua = 0; 2267 2268 /* 2269 * If there's no "feature-barrier" defined, then it means 2270 * we're dealing with a very old backend which writes 2271 * synchronously; nothing to do. 2272 * 2273 * If there are barriers, then we use flush. 2274 */ 2275 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) { 2276 info->feature_flush = 1; 2277 info->feature_fua = 1; 2278 } 2279 2280 /* 2281 * And if there is "feature-flush-cache" use that above 2282 * barriers. 2283 */ 2284 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache", 2285 0)) { 2286 info->feature_flush = 1; 2287 info->feature_fua = 0; 2288 } 2289 2290 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) 2291 blkfront_setup_discard(info); 2292 2293 info->feature_persistent = 2294 !!xenbus_read_unsigned(info->xbdev->otherend, 2295 "feature-persistent", 0); 2296 2297 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend, 2298 "feature-max-indirect-segments", 0); 2299 if (indirect_segments > xen_blkif_max_segments) 2300 indirect_segments = xen_blkif_max_segments; 2301 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST) 2302 indirect_segments = 0; 2303 info->max_indirect_segments = indirect_segments; 2304 } 2305 2306 /* 2307 * Invoked when the backend is finally 'ready' (and has told produced 2308 * the details about the physical device - #sectors, size, etc). 2309 */ 2310 static void blkfront_connect(struct blkfront_info *info) 2311 { 2312 unsigned long long sectors; 2313 unsigned long sector_size; 2314 unsigned int physical_sector_size; 2315 unsigned int binfo; 2316 char *envp[] = { "RESIZE=1", NULL }; 2317 int err, i; 2318 2319 switch (info->connected) { 2320 case BLKIF_STATE_CONNECTED: 2321 /* 2322 * Potentially, the back-end may be signalling 2323 * a capacity change; update the capacity. 2324 */ 2325 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2326 "sectors", "%Lu", §ors); 2327 if (XENBUS_EXIST_ERR(err)) 2328 return; 2329 printk(KERN_INFO "Setting capacity to %Lu\n", 2330 sectors); 2331 set_capacity(info->gd, sectors); 2332 revalidate_disk(info->gd); 2333 kobject_uevent_env(&disk_to_dev(info->gd)->kobj, 2334 KOBJ_CHANGE, envp); 2335 2336 return; 2337 case BLKIF_STATE_SUSPENDED: 2338 /* 2339 * If we are recovering from suspension, we need to wait 2340 * for the backend to announce it's features before 2341 * reconnecting, at least we need to know if the backend 2342 * supports indirect descriptors, and how many. 2343 */ 2344 blkif_recover(info); 2345 return; 2346 2347 default: 2348 break; 2349 } 2350 2351 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 2352 __func__, info->xbdev->otherend); 2353 2354 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2355 "sectors", "%llu", §ors, 2356 "info", "%u", &binfo, 2357 "sector-size", "%lu", §or_size, 2358 NULL); 2359 if (err) { 2360 xenbus_dev_fatal(info->xbdev, err, 2361 "reading backend fields at %s", 2362 info->xbdev->otherend); 2363 return; 2364 } 2365 2366 /* 2367 * physcial-sector-size is a newer field, so old backends may not 2368 * provide this. Assume physical sector size to be the same as 2369 * sector_size in that case. 2370 */ 2371 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend, 2372 "physical-sector-size", 2373 sector_size); 2374 blkfront_gather_backend_features(info); 2375 for (i = 0; i < info->nr_rings; i++) { 2376 err = blkfront_setup_indirect(&info->rinfo[i]); 2377 if (err) { 2378 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 2379 info->xbdev->otherend); 2380 blkif_free(info, 0); 2381 break; 2382 } 2383 } 2384 2385 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 2386 physical_sector_size); 2387 if (err) { 2388 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 2389 info->xbdev->otherend); 2390 goto fail; 2391 } 2392 2393 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2394 2395 /* Kick pending requests. */ 2396 info->connected = BLKIF_STATE_CONNECTED; 2397 for (i = 0; i < info->nr_rings; i++) 2398 kick_pending_request_queues(&info->rinfo[i]); 2399 2400 device_add_disk(&info->xbdev->dev, info->gd); 2401 2402 info->is_ready = 1; 2403 return; 2404 2405 fail: 2406 blkif_free(info, 0); 2407 return; 2408 } 2409 2410 /** 2411 * Callback received when the backend's state changes. 2412 */ 2413 static void blkback_changed(struct xenbus_device *dev, 2414 enum xenbus_state backend_state) 2415 { 2416 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2417 2418 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 2419 2420 switch (backend_state) { 2421 case XenbusStateInitWait: 2422 if (dev->state != XenbusStateInitialising) 2423 break; 2424 if (talk_to_blkback(dev, info)) 2425 break; 2426 case XenbusStateInitialising: 2427 case XenbusStateInitialised: 2428 case XenbusStateReconfiguring: 2429 case XenbusStateReconfigured: 2430 case XenbusStateUnknown: 2431 break; 2432 2433 case XenbusStateConnected: 2434 /* 2435 * talk_to_blkback sets state to XenbusStateInitialised 2436 * and blkfront_connect sets it to XenbusStateConnected 2437 * (if connection went OK). 2438 * 2439 * If the backend (or toolstack) decides to poke at backend 2440 * state (and re-trigger the watch by setting the state repeatedly 2441 * to XenbusStateConnected (4)) we need to deal with this. 2442 * This is allowed as this is used to communicate to the guest 2443 * that the size of disk has changed! 2444 */ 2445 if ((dev->state != XenbusStateInitialised) && 2446 (dev->state != XenbusStateConnected)) { 2447 if (talk_to_blkback(dev, info)) 2448 break; 2449 } 2450 2451 blkfront_connect(info); 2452 break; 2453 2454 case XenbusStateClosed: 2455 if (dev->state == XenbusStateClosed) 2456 break; 2457 /* fall through */ 2458 case XenbusStateClosing: 2459 if (info) 2460 blkfront_closing(info); 2461 break; 2462 } 2463 } 2464 2465 static int blkfront_remove(struct xenbus_device *xbdev) 2466 { 2467 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 2468 struct block_device *bdev = NULL; 2469 struct gendisk *disk; 2470 2471 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 2472 2473 blkif_free(info, 0); 2474 2475 mutex_lock(&info->mutex); 2476 2477 disk = info->gd; 2478 if (disk) 2479 bdev = bdget_disk(disk, 0); 2480 2481 info->xbdev = NULL; 2482 mutex_unlock(&info->mutex); 2483 2484 if (!bdev) { 2485 kfree(info); 2486 return 0; 2487 } 2488 2489 /* 2490 * The xbdev was removed before we reached the Closed 2491 * state. See if it's safe to remove the disk. If the bdev 2492 * isn't closed yet, we let release take care of it. 2493 */ 2494 2495 mutex_lock(&bdev->bd_mutex); 2496 info = disk->private_data; 2497 2498 dev_warn(disk_to_dev(disk), 2499 "%s was hot-unplugged, %d stale handles\n", 2500 xbdev->nodename, bdev->bd_openers); 2501 2502 if (info && !bdev->bd_openers) { 2503 xlvbd_release_gendisk(info); 2504 disk->private_data = NULL; 2505 kfree(info); 2506 } 2507 2508 mutex_unlock(&bdev->bd_mutex); 2509 bdput(bdev); 2510 2511 return 0; 2512 } 2513 2514 static int blkfront_is_ready(struct xenbus_device *dev) 2515 { 2516 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2517 2518 return info->is_ready && info->xbdev; 2519 } 2520 2521 static int blkif_open(struct block_device *bdev, fmode_t mode) 2522 { 2523 struct gendisk *disk = bdev->bd_disk; 2524 struct blkfront_info *info; 2525 int err = 0; 2526 2527 mutex_lock(&blkfront_mutex); 2528 2529 info = disk->private_data; 2530 if (!info) { 2531 /* xbdev gone */ 2532 err = -ERESTARTSYS; 2533 goto out; 2534 } 2535 2536 mutex_lock(&info->mutex); 2537 2538 if (!info->gd) 2539 /* xbdev is closed */ 2540 err = -ERESTARTSYS; 2541 2542 mutex_unlock(&info->mutex); 2543 2544 out: 2545 mutex_unlock(&blkfront_mutex); 2546 return err; 2547 } 2548 2549 static void blkif_release(struct gendisk *disk, fmode_t mode) 2550 { 2551 struct blkfront_info *info = disk->private_data; 2552 struct block_device *bdev; 2553 struct xenbus_device *xbdev; 2554 2555 mutex_lock(&blkfront_mutex); 2556 2557 bdev = bdget_disk(disk, 0); 2558 2559 if (!bdev) { 2560 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2561 goto out_mutex; 2562 } 2563 if (bdev->bd_openers) 2564 goto out; 2565 2566 /* 2567 * Check if we have been instructed to close. We will have 2568 * deferred this request, because the bdev was still open. 2569 */ 2570 2571 mutex_lock(&info->mutex); 2572 xbdev = info->xbdev; 2573 2574 if (xbdev && xbdev->state == XenbusStateClosing) { 2575 /* pending switch to state closed */ 2576 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2577 xlvbd_release_gendisk(info); 2578 xenbus_frontend_closed(info->xbdev); 2579 } 2580 2581 mutex_unlock(&info->mutex); 2582 2583 if (!xbdev) { 2584 /* sudden device removal */ 2585 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2586 xlvbd_release_gendisk(info); 2587 disk->private_data = NULL; 2588 kfree(info); 2589 } 2590 2591 out: 2592 bdput(bdev); 2593 out_mutex: 2594 mutex_unlock(&blkfront_mutex); 2595 } 2596 2597 static const struct block_device_operations xlvbd_block_fops = 2598 { 2599 .owner = THIS_MODULE, 2600 .open = blkif_open, 2601 .release = blkif_release, 2602 .getgeo = blkif_getgeo, 2603 .ioctl = blkif_ioctl, 2604 }; 2605 2606 2607 static const struct xenbus_device_id blkfront_ids[] = { 2608 { "vbd" }, 2609 { "" } 2610 }; 2611 2612 static struct xenbus_driver blkfront_driver = { 2613 .ids = blkfront_ids, 2614 .probe = blkfront_probe, 2615 .remove = blkfront_remove, 2616 .resume = blkfront_resume, 2617 .otherend_changed = blkback_changed, 2618 .is_ready = blkfront_is_ready, 2619 }; 2620 2621 static int __init xlblk_init(void) 2622 { 2623 int ret; 2624 int nr_cpus = num_online_cpus(); 2625 2626 if (!xen_domain()) 2627 return -ENODEV; 2628 2629 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST) 2630 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2631 2632 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { 2633 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 2634 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); 2635 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 2636 } 2637 2638 if (xen_blkif_max_queues > nr_cpus) { 2639 pr_info("Invalid max_queues (%d), will use default max: %d.\n", 2640 xen_blkif_max_queues, nr_cpus); 2641 xen_blkif_max_queues = nr_cpus; 2642 } 2643 2644 if (!xen_has_pv_disk_devices()) 2645 return -ENODEV; 2646 2647 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2648 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2649 XENVBD_MAJOR, DEV_NAME); 2650 return -ENODEV; 2651 } 2652 2653 ret = xenbus_register_frontend(&blkfront_driver); 2654 if (ret) { 2655 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2656 return ret; 2657 } 2658 2659 return 0; 2660 } 2661 module_init(xlblk_init); 2662 2663 2664 static void __exit xlblk_exit(void) 2665 { 2666 xenbus_unregister_driver(&blkfront_driver); 2667 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2668 kfree(minors); 2669 } 2670 module_exit(xlblk_exit); 2671 2672 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2673 MODULE_LICENSE("GPL"); 2674 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2675 MODULE_ALIAS("xen:vbd"); 2676 MODULE_ALIAS("xenblk"); 2677