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/major.h> 46#include <linux/mutex.h> 47#include <linux/scatterlist.h> 48#include <linux/bitmap.h> 49#include <linux/list.h> 50#include <linux/workqueue.h> 51#include <linux/sched/mm.h> 52 53#include <xen/xen.h> 54#include <xen/xenbus.h> 55#include <xen/grant_table.h> 56#include <xen/events.h> 57#include <xen/page.h> 58#include <xen/platform_pci.h> 59 60#include <xen/interface/grant_table.h> 61#include <xen/interface/io/blkif.h> 62#include <xen/interface/io/protocols.h> 63 64#include <asm/xen/hypervisor.h> 65 66/* 67 * The minimal size of segment supported by the block framework is PAGE_SIZE. 68 * When Linux is using a different page size than Xen, it may not be possible 69 * to put all the data in a single segment. 70 * This can happen when the backend doesn't support indirect descriptor and 71 * therefore the maximum amount of data that a request can carry is 72 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB 73 * 74 * Note that we only support one extra request. So the Linux page size 75 * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) = 76 * 88KB. 77 */ 78#define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE) 79 80enum blkif_state { 81 BLKIF_STATE_DISCONNECTED, 82 BLKIF_STATE_CONNECTED, 83 BLKIF_STATE_SUSPENDED, 84 BLKIF_STATE_ERROR, 85}; 86 87struct grant { 88 grant_ref_t gref; 89 struct page *page; 90 struct list_head node; 91}; 92 93enum blk_req_status { 94 REQ_PROCESSING, 95 REQ_WAITING, 96 REQ_DONE, 97 REQ_ERROR, 98 REQ_EOPNOTSUPP, 99}; 100 101struct blk_shadow { 102 struct blkif_request req; 103 struct request *request; 104 struct grant **grants_used; 105 struct grant **indirect_grants; 106 struct scatterlist *sg; 107 unsigned int num_sg; 108 enum blk_req_status status; 109 110 #define NO_ASSOCIATED_ID ~0UL 111 /* 112 * Id of the sibling if we ever need 2 requests when handling a 113 * block I/O request 114 */ 115 unsigned long associated_id; 116}; 117 118struct blkif_req { 119 blk_status_t error; 120}; 121 122static inline struct blkif_req *blkif_req(struct request *rq) 123{ 124 return blk_mq_rq_to_pdu(rq); 125} 126 127static DEFINE_MUTEX(blkfront_mutex); 128static const struct block_device_operations xlvbd_block_fops; 129static struct delayed_work blkfront_work; 130static LIST_HEAD(info_list); 131 132/* 133 * Maximum number of segments in indirect requests, the actual value used by 134 * the frontend driver is the minimum of this value and the value provided 135 * by the backend driver. 136 */ 137 138static unsigned int xen_blkif_max_segments = 32; 139module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444); 140MODULE_PARM_DESC(max_indirect_segments, 141 "Maximum amount of segments in indirect requests (default is 32)"); 142 143static unsigned int xen_blkif_max_queues = 4; 144module_param_named(max_queues, xen_blkif_max_queues, uint, 0444); 145MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk"); 146 147/* 148 * Maximum order of pages to be used for the shared ring between front and 149 * backend, 4KB page granularity is used. 150 */ 151static unsigned int xen_blkif_max_ring_order; 152module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444); 153MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 154 155static bool __read_mostly xen_blkif_trusted = true; 156module_param_named(trusted, xen_blkif_trusted, bool, 0644); 157MODULE_PARM_DESC(trusted, "Is the backend trusted"); 158 159#define BLK_RING_SIZE(info) \ 160 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages) 161 162/* 163 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 164 * characters are enough. Define to 20 to keep consistent with backend. 165 */ 166#define RINGREF_NAME_LEN (20) 167/* 168 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters. 169 */ 170#define QUEUE_NAME_LEN (17) 171 172/* 173 * Per-ring info. 174 * Every blkfront device can associate with one or more blkfront_ring_info, 175 * depending on how many hardware queues/rings to be used. 176 */ 177struct blkfront_ring_info { 178 /* Lock to protect data in every ring buffer. */ 179 spinlock_t ring_lock; 180 struct blkif_front_ring ring; 181 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS]; 182 unsigned int evtchn, irq; 183 struct work_struct work; 184 struct gnttab_free_callback callback; 185 struct list_head indirect_pages; 186 struct list_head grants; 187 unsigned int persistent_gnts_c; 188 unsigned long shadow_free; 189 struct blkfront_info *dev_info; 190 struct blk_shadow shadow[]; 191}; 192 193/* 194 * We have one of these per vbd, whether ide, scsi or 'other'. They 195 * hang in private_data off the gendisk structure. We may end up 196 * putting all kinds of interesting stuff here :-) 197 */ 198struct blkfront_info 199{ 200 struct mutex mutex; 201 struct xenbus_device *xbdev; 202 struct gendisk *gd; 203 u16 sector_size; 204 unsigned int physical_sector_size; 205 unsigned long vdisk_info; 206 int vdevice; 207 blkif_vdev_t handle; 208 enum blkif_state connected; 209 /* Number of pages per ring buffer. */ 210 unsigned int nr_ring_pages; 211 struct request_queue *rq; 212 unsigned int feature_flush:1; 213 unsigned int feature_fua:1; 214 unsigned int feature_discard:1; 215 unsigned int feature_secdiscard:1; 216 /* Connect-time cached feature_persistent parameter */ 217 unsigned int feature_persistent_parm:1; 218 /* Persistent grants feature negotiation result */ 219 unsigned int feature_persistent:1; 220 unsigned int bounce:1; 221 unsigned int discard_granularity; 222 unsigned int discard_alignment; 223 /* Number of 4KB segments handled */ 224 unsigned int max_indirect_segments; 225 int is_ready; 226 struct blk_mq_tag_set tag_set; 227 struct blkfront_ring_info *rinfo; 228 unsigned int nr_rings; 229 unsigned int rinfo_size; 230 /* Save uncomplete reqs and bios for migration. */ 231 struct list_head requests; 232 struct bio_list bio_list; 233 struct list_head info_list; 234}; 235 236static unsigned int nr_minors; 237static unsigned long *minors; 238static DEFINE_SPINLOCK(minor_lock); 239 240#define PARTS_PER_DISK 16 241#define PARTS_PER_EXT_DISK 256 242 243#define BLKIF_MAJOR(dev) ((dev)>>8) 244#define BLKIF_MINOR(dev) ((dev) & 0xff) 245 246#define EXT_SHIFT 28 247#define EXTENDED (1<<EXT_SHIFT) 248#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 249#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 250#define EMULATED_HD_DISK_MINOR_OFFSET (0) 251#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 252#define EMULATED_SD_DISK_MINOR_OFFSET (0) 253#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 254 255#define DEV_NAME "xvd" /* name in /dev */ 256 257/* 258 * Grants are always the same size as a Xen page (i.e 4KB). 259 * A physical segment is always the same size as a Linux page. 260 * Number of grants per physical segment 261 */ 262#define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE) 263 264#define GRANTS_PER_INDIRECT_FRAME \ 265 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment)) 266 267#define INDIRECT_GREFS(_grants) \ 268 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME) 269 270static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo); 271static void blkfront_gather_backend_features(struct blkfront_info *info); 272static int negotiate_mq(struct blkfront_info *info); 273 274#define for_each_rinfo(info, ptr, idx) \ 275 for ((ptr) = (info)->rinfo, (idx) = 0; \ 276 (idx) < (info)->nr_rings; \ 277 (idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size) 278 279static inline struct blkfront_ring_info * 280get_rinfo(const struct blkfront_info *info, unsigned int i) 281{ 282 BUG_ON(i >= info->nr_rings); 283 return (void *)info->rinfo + i * info->rinfo_size; 284} 285 286static int get_id_from_freelist(struct blkfront_ring_info *rinfo) 287{ 288 unsigned long free = rinfo->shadow_free; 289 290 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info)); 291 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id; 292 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 293 return free; 294} 295 296static int add_id_to_freelist(struct blkfront_ring_info *rinfo, 297 unsigned long id) 298{ 299 if (rinfo->shadow[id].req.u.rw.id != id) 300 return -EINVAL; 301 if (rinfo->shadow[id].request == NULL) 302 return -EINVAL; 303 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free; 304 rinfo->shadow[id].request = NULL; 305 rinfo->shadow_free = id; 306 return 0; 307} 308 309static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 310{ 311 struct blkfront_info *info = rinfo->dev_info; 312 struct page *granted_page; 313 struct grant *gnt_list_entry, *n; 314 int i = 0; 315 316 while (i < num) { 317 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 318 if (!gnt_list_entry) 319 goto out_of_memory; 320 321 if (info->bounce) { 322 granted_page = alloc_page(GFP_NOIO | __GFP_ZERO); 323 if (!granted_page) { 324 kfree(gnt_list_entry); 325 goto out_of_memory; 326 } 327 gnt_list_entry->page = granted_page; 328 } 329 330 gnt_list_entry->gref = INVALID_GRANT_REF; 331 list_add(&gnt_list_entry->node, &rinfo->grants); 332 i++; 333 } 334 335 return 0; 336 337out_of_memory: 338 list_for_each_entry_safe(gnt_list_entry, n, 339 &rinfo->grants, node) { 340 list_del(&gnt_list_entry->node); 341 if (info->bounce) 342 __free_page(gnt_list_entry->page); 343 kfree(gnt_list_entry); 344 i--; 345 } 346 BUG_ON(i != 0); 347 return -ENOMEM; 348} 349 350static struct grant *get_free_grant(struct blkfront_ring_info *rinfo) 351{ 352 struct grant *gnt_list_entry; 353 354 BUG_ON(list_empty(&rinfo->grants)); 355 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant, 356 node); 357 list_del(&gnt_list_entry->node); 358 359 if (gnt_list_entry->gref != INVALID_GRANT_REF) 360 rinfo->persistent_gnts_c--; 361 362 return gnt_list_entry; 363} 364 365static inline void grant_foreign_access(const struct grant *gnt_list_entry, 366 const struct blkfront_info *info) 367{ 368 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref, 369 info->xbdev->otherend_id, 370 gnt_list_entry->page, 371 0); 372} 373 374static struct grant *get_grant(grant_ref_t *gref_head, 375 unsigned long gfn, 376 struct blkfront_ring_info *rinfo) 377{ 378 struct grant *gnt_list_entry = get_free_grant(rinfo); 379 struct blkfront_info *info = rinfo->dev_info; 380 381 if (gnt_list_entry->gref != INVALID_GRANT_REF) 382 return gnt_list_entry; 383 384 /* Assign a gref to this page */ 385 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 386 BUG_ON(gnt_list_entry->gref == -ENOSPC); 387 if (info->bounce) 388 grant_foreign_access(gnt_list_entry, info); 389 else { 390 /* Grant access to the GFN passed by the caller */ 391 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 392 info->xbdev->otherend_id, 393 gfn, 0); 394 } 395 396 return gnt_list_entry; 397} 398 399static struct grant *get_indirect_grant(grant_ref_t *gref_head, 400 struct blkfront_ring_info *rinfo) 401{ 402 struct grant *gnt_list_entry = get_free_grant(rinfo); 403 struct blkfront_info *info = rinfo->dev_info; 404 405 if (gnt_list_entry->gref != INVALID_GRANT_REF) 406 return gnt_list_entry; 407 408 /* Assign a gref to this page */ 409 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 410 BUG_ON(gnt_list_entry->gref == -ENOSPC); 411 if (!info->bounce) { 412 struct page *indirect_page; 413 414 /* Fetch a pre-allocated page to use for indirect grefs */ 415 BUG_ON(list_empty(&rinfo->indirect_pages)); 416 indirect_page = list_first_entry(&rinfo->indirect_pages, 417 struct page, lru); 418 list_del(&indirect_page->lru); 419 gnt_list_entry->page = indirect_page; 420 } 421 grant_foreign_access(gnt_list_entry, info); 422 423 return gnt_list_entry; 424} 425 426static const char *op_name(int op) 427{ 428 static const char *const names[] = { 429 [BLKIF_OP_READ] = "read", 430 [BLKIF_OP_WRITE] = "write", 431 [BLKIF_OP_WRITE_BARRIER] = "barrier", 432 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 433 [BLKIF_OP_DISCARD] = "discard" }; 434 435 if (op < 0 || op >= ARRAY_SIZE(names)) 436 return "unknown"; 437 438 if (!names[op]) 439 return "reserved"; 440 441 return names[op]; 442} 443static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 444{ 445 unsigned int end = minor + nr; 446 int rc; 447 448 if (end > nr_minors) { 449 unsigned long *bitmap, *old; 450 451 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 452 GFP_KERNEL); 453 if (bitmap == NULL) 454 return -ENOMEM; 455 456 spin_lock(&minor_lock); 457 if (end > nr_minors) { 458 old = minors; 459 memcpy(bitmap, minors, 460 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 461 minors = bitmap; 462 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 463 } else 464 old = bitmap; 465 spin_unlock(&minor_lock); 466 kfree(old); 467 } 468 469 spin_lock(&minor_lock); 470 if (find_next_bit(minors, end, minor) >= end) { 471 bitmap_set(minors, minor, nr); 472 rc = 0; 473 } else 474 rc = -EBUSY; 475 spin_unlock(&minor_lock); 476 477 return rc; 478} 479 480static void xlbd_release_minors(unsigned int minor, unsigned int nr) 481{ 482 unsigned int end = minor + nr; 483 484 BUG_ON(end > nr_minors); 485 spin_lock(&minor_lock); 486 bitmap_clear(minors, minor, nr); 487 spin_unlock(&minor_lock); 488} 489 490static void blkif_restart_queue_callback(void *arg) 491{ 492 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg; 493 schedule_work(&rinfo->work); 494} 495 496static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 497{ 498 /* We don't have real geometry info, but let's at least return 499 values consistent with the size of the device */ 500 sector_t nsect = get_capacity(bd->bd_disk); 501 sector_t cylinders = nsect; 502 503 hg->heads = 0xff; 504 hg->sectors = 0x3f; 505 sector_div(cylinders, hg->heads * hg->sectors); 506 hg->cylinders = cylinders; 507 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 508 hg->cylinders = 0xffff; 509 return 0; 510} 511 512static int blkif_ioctl(struct block_device *bdev, blk_mode_t mode, 513 unsigned command, unsigned long argument) 514{ 515 struct blkfront_info *info = bdev->bd_disk->private_data; 516 int i; 517 518 switch (command) { 519 case CDROMMULTISESSION: 520 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 521 if (put_user(0, (char __user *)(argument + i))) 522 return -EFAULT; 523 return 0; 524 case CDROM_GET_CAPABILITY: 525 if (!(info->vdisk_info & VDISK_CDROM)) 526 return -EINVAL; 527 return 0; 528 default: 529 return -EINVAL; 530 } 531} 532 533static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, 534 struct request *req, 535 struct blkif_request **ring_req) 536{ 537 unsigned long id; 538 539 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt); 540 rinfo->ring.req_prod_pvt++; 541 542 id = get_id_from_freelist(rinfo); 543 rinfo->shadow[id].request = req; 544 rinfo->shadow[id].status = REQ_PROCESSING; 545 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID; 546 547 rinfo->shadow[id].req.u.rw.id = id; 548 549 return id; 550} 551 552static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo) 553{ 554 struct blkfront_info *info = rinfo->dev_info; 555 struct blkif_request *ring_req, *final_ring_req; 556 unsigned long id; 557 558 /* Fill out a communications ring structure. */ 559 id = blkif_ring_get_request(rinfo, req, &final_ring_req); 560 ring_req = &rinfo->shadow[id].req; 561 562 ring_req->operation = BLKIF_OP_DISCARD; 563 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 564 ring_req->u.discard.id = id; 565 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 566 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard) 567 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 568 else 569 ring_req->u.discard.flag = 0; 570 571 /* Copy the request to the ring page. */ 572 *final_ring_req = *ring_req; 573 rinfo->shadow[id].status = REQ_WAITING; 574 575 return 0; 576} 577 578struct setup_rw_req { 579 unsigned int grant_idx; 580 struct blkif_request_segment *segments; 581 struct blkfront_ring_info *rinfo; 582 struct blkif_request *ring_req; 583 grant_ref_t gref_head; 584 unsigned int id; 585 /* Only used when persistent grant is used and it's a write request */ 586 bool need_copy; 587 unsigned int bvec_off; 588 char *bvec_data; 589 590 bool require_extra_req; 591 struct blkif_request *extra_ring_req; 592}; 593 594static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset, 595 unsigned int len, void *data) 596{ 597 struct setup_rw_req *setup = data; 598 int n, ref; 599 struct grant *gnt_list_entry; 600 unsigned int fsect, lsect; 601 /* Convenient aliases */ 602 unsigned int grant_idx = setup->grant_idx; 603 struct blkif_request *ring_req = setup->ring_req; 604 struct blkfront_ring_info *rinfo = setup->rinfo; 605 /* 606 * We always use the shadow of the first request to store the list 607 * of grant associated to the block I/O request. This made the 608 * completion more easy to handle even if the block I/O request is 609 * split. 610 */ 611 struct blk_shadow *shadow = &rinfo->shadow[setup->id]; 612 613 if (unlikely(setup->require_extra_req && 614 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 615 /* 616 * We are using the second request, setup grant_idx 617 * to be the index of the segment array. 618 */ 619 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST; 620 ring_req = setup->extra_ring_req; 621 } 622 623 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 624 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) { 625 if (setup->segments) 626 kunmap_atomic(setup->segments); 627 628 n = grant_idx / GRANTS_PER_INDIRECT_FRAME; 629 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo); 630 shadow->indirect_grants[n] = gnt_list_entry; 631 setup->segments = kmap_atomic(gnt_list_entry->page); 632 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 633 } 634 635 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo); 636 ref = gnt_list_entry->gref; 637 /* 638 * All the grants are stored in the shadow of the first 639 * request. Therefore we have to use the global index. 640 */ 641 shadow->grants_used[setup->grant_idx] = gnt_list_entry; 642 643 if (setup->need_copy) { 644 void *shared_data; 645 646 shared_data = kmap_atomic(gnt_list_entry->page); 647 /* 648 * this does not wipe data stored outside the 649 * range sg->offset..sg->offset+sg->length. 650 * Therefore, blkback *could* see data from 651 * previous requests. This is OK as long as 652 * persistent grants are shared with just one 653 * domain. It may need refactoring if this 654 * changes 655 */ 656 memcpy(shared_data + offset, 657 setup->bvec_data + setup->bvec_off, 658 len); 659 660 kunmap_atomic(shared_data); 661 setup->bvec_off += len; 662 } 663 664 fsect = offset >> 9; 665 lsect = fsect + (len >> 9) - 1; 666 if (ring_req->operation != BLKIF_OP_INDIRECT) { 667 ring_req->u.rw.seg[grant_idx] = 668 (struct blkif_request_segment) { 669 .gref = ref, 670 .first_sect = fsect, 671 .last_sect = lsect }; 672 } else { 673 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] = 674 (struct blkif_request_segment) { 675 .gref = ref, 676 .first_sect = fsect, 677 .last_sect = lsect }; 678 } 679 680 (setup->grant_idx)++; 681} 682 683static void blkif_setup_extra_req(struct blkif_request *first, 684 struct blkif_request *second) 685{ 686 uint16_t nr_segments = first->u.rw.nr_segments; 687 688 /* 689 * The second request is only present when the first request uses 690 * all its segments. It's always the continuity of the first one. 691 */ 692 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 693 694 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST; 695 second->u.rw.sector_number = first->u.rw.sector_number + 696 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512; 697 698 second->u.rw.handle = first->u.rw.handle; 699 second->operation = first->operation; 700} 701 702static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo) 703{ 704 struct blkfront_info *info = rinfo->dev_info; 705 struct blkif_request *ring_req, *extra_ring_req = NULL; 706 struct blkif_request *final_ring_req, *final_extra_ring_req = NULL; 707 unsigned long id, extra_id = NO_ASSOCIATED_ID; 708 bool require_extra_req = false; 709 int i; 710 struct setup_rw_req setup = { 711 .grant_idx = 0, 712 .segments = NULL, 713 .rinfo = rinfo, 714 .need_copy = rq_data_dir(req) && info->bounce, 715 }; 716 717 /* 718 * Used to store if we are able to queue the request by just using 719 * existing persistent grants, or if we have to get new grants, 720 * as there are not sufficiently many free. 721 */ 722 bool new_persistent_gnts = false; 723 struct scatterlist *sg; 724 int num_sg, max_grefs, num_grant; 725 726 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG; 727 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 728 /* 729 * If we are using indirect segments we need to account 730 * for the indirect grefs used in the request. 731 */ 732 max_grefs += INDIRECT_GREFS(max_grefs); 733 734 /* Check if we have enough persistent grants to allocate a requests */ 735 if (rinfo->persistent_gnts_c < max_grefs) { 736 new_persistent_gnts = true; 737 738 if (gnttab_alloc_grant_references( 739 max_grefs - rinfo->persistent_gnts_c, 740 &setup.gref_head) < 0) { 741 gnttab_request_free_callback( 742 &rinfo->callback, 743 blkif_restart_queue_callback, 744 rinfo, 745 max_grefs - rinfo->persistent_gnts_c); 746 return 1; 747 } 748 } 749 750 /* Fill out a communications ring structure. */ 751 id = blkif_ring_get_request(rinfo, req, &final_ring_req); 752 ring_req = &rinfo->shadow[id].req; 753 754 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg); 755 num_grant = 0; 756 /* Calculate the number of grant used */ 757 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) 758 num_grant += gnttab_count_grant(sg->offset, sg->length); 759 760 require_extra_req = info->max_indirect_segments == 0 && 761 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST; 762 BUG_ON(!HAS_EXTRA_REQ && require_extra_req); 763 764 rinfo->shadow[id].num_sg = num_sg; 765 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST && 766 likely(!require_extra_req)) { 767 /* 768 * The indirect operation can only be a BLKIF_OP_READ or 769 * BLKIF_OP_WRITE 770 */ 771 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA); 772 ring_req->operation = BLKIF_OP_INDIRECT; 773 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 774 BLKIF_OP_WRITE : BLKIF_OP_READ; 775 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 776 ring_req->u.indirect.handle = info->handle; 777 ring_req->u.indirect.nr_segments = num_grant; 778 } else { 779 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 780 ring_req->u.rw.handle = info->handle; 781 ring_req->operation = rq_data_dir(req) ? 782 BLKIF_OP_WRITE : BLKIF_OP_READ; 783 if (req_op(req) == REQ_OP_FLUSH || 784 (req_op(req) == REQ_OP_WRITE && (req->cmd_flags & REQ_FUA))) { 785 /* 786 * Ideally we can do an unordered flush-to-disk. 787 * In case the backend onlysupports barriers, use that. 788 * A barrier request a superset of FUA, so we can 789 * implement it the same way. (It's also a FLUSH+FUA, 790 * since it is guaranteed ordered WRT previous writes.) 791 */ 792 if (info->feature_flush && info->feature_fua) 793 ring_req->operation = 794 BLKIF_OP_WRITE_BARRIER; 795 else if (info->feature_flush) 796 ring_req->operation = 797 BLKIF_OP_FLUSH_DISKCACHE; 798 else 799 ring_req->operation = 0; 800 } 801 ring_req->u.rw.nr_segments = num_grant; 802 if (unlikely(require_extra_req)) { 803 extra_id = blkif_ring_get_request(rinfo, req, 804 &final_extra_ring_req); 805 extra_ring_req = &rinfo->shadow[extra_id].req; 806 807 /* 808 * Only the first request contains the scatter-gather 809 * list. 810 */ 811 rinfo->shadow[extra_id].num_sg = 0; 812 813 blkif_setup_extra_req(ring_req, extra_ring_req); 814 815 /* Link the 2 requests together */ 816 rinfo->shadow[extra_id].associated_id = id; 817 rinfo->shadow[id].associated_id = extra_id; 818 } 819 } 820 821 setup.ring_req = ring_req; 822 setup.id = id; 823 824 setup.require_extra_req = require_extra_req; 825 if (unlikely(require_extra_req)) 826 setup.extra_ring_req = extra_ring_req; 827 828 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) { 829 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 830 831 if (setup.need_copy) { 832 setup.bvec_off = sg->offset; 833 setup.bvec_data = kmap_atomic(sg_page(sg)); 834 } 835 836 gnttab_foreach_grant_in_range(sg_page(sg), 837 sg->offset, 838 sg->length, 839 blkif_setup_rw_req_grant, 840 &setup); 841 842 if (setup.need_copy) 843 kunmap_atomic(setup.bvec_data); 844 } 845 if (setup.segments) 846 kunmap_atomic(setup.segments); 847 848 /* Copy request(s) to the ring page. */ 849 *final_ring_req = *ring_req; 850 rinfo->shadow[id].status = REQ_WAITING; 851 if (unlikely(require_extra_req)) { 852 *final_extra_ring_req = *extra_ring_req; 853 rinfo->shadow[extra_id].status = REQ_WAITING; 854 } 855 856 if (new_persistent_gnts) 857 gnttab_free_grant_references(setup.gref_head); 858 859 return 0; 860} 861 862/* 863 * Generate a Xen blkfront IO request from a blk layer request. Reads 864 * and writes are handled as expected. 865 * 866 * @req: a request struct 867 */ 868static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo) 869{ 870 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED)) 871 return 1; 872 873 if (unlikely(req_op(req) == REQ_OP_DISCARD || 874 req_op(req) == REQ_OP_SECURE_ERASE)) 875 return blkif_queue_discard_req(req, rinfo); 876 else 877 return blkif_queue_rw_req(req, rinfo); 878} 879 880static inline void flush_requests(struct blkfront_ring_info *rinfo) 881{ 882 int notify; 883 884 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify); 885 886 if (notify) 887 notify_remote_via_irq(rinfo->irq); 888} 889 890static inline bool blkif_request_flush_invalid(struct request *req, 891 struct blkfront_info *info) 892{ 893 return (blk_rq_is_passthrough(req) || 894 ((req_op(req) == REQ_OP_FLUSH) && 895 !info->feature_flush) || 896 ((req->cmd_flags & REQ_FUA) && 897 !info->feature_fua)); 898} 899 900static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx, 901 const struct blk_mq_queue_data *qd) 902{ 903 unsigned long flags; 904 int qid = hctx->queue_num; 905 struct blkfront_info *info = hctx->queue->queuedata; 906 struct blkfront_ring_info *rinfo = NULL; 907 908 rinfo = get_rinfo(info, qid); 909 blk_mq_start_request(qd->rq); 910 spin_lock_irqsave(&rinfo->ring_lock, flags); 911 if (RING_FULL(&rinfo->ring)) 912 goto out_busy; 913 914 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info)) 915 goto out_err; 916 917 if (blkif_queue_request(qd->rq, rinfo)) 918 goto out_busy; 919 920 flush_requests(rinfo); 921 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 922 return BLK_STS_OK; 923 924out_err: 925 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 926 return BLK_STS_IOERR; 927 928out_busy: 929 blk_mq_stop_hw_queue(hctx); 930 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 931 return BLK_STS_DEV_RESOURCE; 932} 933 934static void blkif_complete_rq(struct request *rq) 935{ 936 blk_mq_end_request(rq, blkif_req(rq)->error); 937} 938 939static const struct blk_mq_ops blkfront_mq_ops = { 940 .queue_rq = blkif_queue_rq, 941 .complete = blkif_complete_rq, 942}; 943 944static void blkif_set_queue_limits(const struct blkfront_info *info, 945 struct queue_limits *lim) 946{ 947 unsigned int segments = info->max_indirect_segments ? : 948 BLKIF_MAX_SEGMENTS_PER_REQUEST; 949 950 if (info->feature_discard) { 951 lim->max_hw_discard_sectors = UINT_MAX; 952 if (info->discard_granularity) 953 lim->discard_granularity = info->discard_granularity; 954 lim->discard_alignment = info->discard_alignment; 955 if (info->feature_secdiscard) 956 lim->max_secure_erase_sectors = UINT_MAX; 957 } 958 959 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 960 lim->logical_block_size = info->sector_size; 961 lim->physical_block_size = info->physical_sector_size; 962 lim->max_hw_sectors = (segments * XEN_PAGE_SIZE) / 512; 963 964 /* Each segment in a request is up to an aligned page in size. */ 965 lim->seg_boundary_mask = PAGE_SIZE - 1; 966 lim->max_segment_size = PAGE_SIZE; 967 968 /* Ensure a merged request will fit in a single I/O ring slot. */ 969 lim->max_segments = segments / GRANTS_PER_PSEG; 970 971 /* Make sure buffer addresses are sector-aligned. */ 972 lim->dma_alignment = 511; 973} 974 975static const char *flush_info(struct blkfront_info *info) 976{ 977 if (info->feature_flush && info->feature_fua) 978 return "barrier: enabled;"; 979 else if (info->feature_flush) 980 return "flush diskcache: enabled;"; 981 else 982 return "barrier or flush: disabled;"; 983} 984 985static void xlvbd_flush(struct blkfront_info *info) 986{ 987 blk_queue_write_cache(info->rq, info->feature_flush ? true : false, 988 info->feature_fua ? true : false); 989 pr_info("blkfront: %s: %s %s %s %s %s %s %s\n", 990 info->gd->disk_name, flush_info(info), 991 "persistent grants:", info->feature_persistent ? 992 "enabled;" : "disabled;", "indirect descriptors:", 993 info->max_indirect_segments ? "enabled;" : "disabled;", 994 "bounce buffer:", info->bounce ? "enabled" : "disabled;"); 995} 996 997static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 998{ 999 int major; 1000 major = BLKIF_MAJOR(vdevice); 1001 *minor = BLKIF_MINOR(vdevice); 1002 switch (major) { 1003 case XEN_IDE0_MAJOR: 1004 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 1005 *minor = ((*minor / 64) * PARTS_PER_DISK) + 1006 EMULATED_HD_DISK_MINOR_OFFSET; 1007 break; 1008 case XEN_IDE1_MAJOR: 1009 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 1010 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 1011 EMULATED_HD_DISK_MINOR_OFFSET; 1012 break; 1013 case XEN_SCSI_DISK0_MAJOR: 1014 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 1015 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 1016 break; 1017 case XEN_SCSI_DISK1_MAJOR: 1018 case XEN_SCSI_DISK2_MAJOR: 1019 case XEN_SCSI_DISK3_MAJOR: 1020 case XEN_SCSI_DISK4_MAJOR: 1021 case XEN_SCSI_DISK5_MAJOR: 1022 case XEN_SCSI_DISK6_MAJOR: 1023 case XEN_SCSI_DISK7_MAJOR: 1024 *offset = (*minor / PARTS_PER_DISK) + 1025 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 1026 EMULATED_SD_DISK_NAME_OFFSET; 1027 *minor = *minor + 1028 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 1029 EMULATED_SD_DISK_MINOR_OFFSET; 1030 break; 1031 case XEN_SCSI_DISK8_MAJOR: 1032 case XEN_SCSI_DISK9_MAJOR: 1033 case XEN_SCSI_DISK10_MAJOR: 1034 case XEN_SCSI_DISK11_MAJOR: 1035 case XEN_SCSI_DISK12_MAJOR: 1036 case XEN_SCSI_DISK13_MAJOR: 1037 case XEN_SCSI_DISK14_MAJOR: 1038 case XEN_SCSI_DISK15_MAJOR: 1039 *offset = (*minor / PARTS_PER_DISK) + 1040 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 1041 EMULATED_SD_DISK_NAME_OFFSET; 1042 *minor = *minor + 1043 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 1044 EMULATED_SD_DISK_MINOR_OFFSET; 1045 break; 1046 case XENVBD_MAJOR: 1047 *offset = *minor / PARTS_PER_DISK; 1048 break; 1049 default: 1050 printk(KERN_WARNING "blkfront: your disk configuration is " 1051 "incorrect, please use an xvd device instead\n"); 1052 return -ENODEV; 1053 } 1054 return 0; 1055} 1056 1057static char *encode_disk_name(char *ptr, unsigned int n) 1058{ 1059 if (n >= 26) 1060 ptr = encode_disk_name(ptr, n / 26 - 1); 1061 *ptr = 'a' + n % 26; 1062 return ptr + 1; 1063} 1064 1065static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 1066 struct blkfront_info *info, u16 sector_size, 1067 unsigned int physical_sector_size) 1068{ 1069 struct queue_limits lim = {}; 1070 struct gendisk *gd; 1071 int nr_minors = 1; 1072 int err; 1073 unsigned int offset; 1074 int minor; 1075 int nr_parts; 1076 char *ptr; 1077 1078 BUG_ON(info->gd != NULL); 1079 BUG_ON(info->rq != NULL); 1080 1081 if ((info->vdevice>>EXT_SHIFT) > 1) { 1082 /* this is above the extended range; something is wrong */ 1083 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 1084 return -ENODEV; 1085 } 1086 1087 if (!VDEV_IS_EXTENDED(info->vdevice)) { 1088 err = xen_translate_vdev(info->vdevice, &minor, &offset); 1089 if (err) 1090 return err; 1091 nr_parts = PARTS_PER_DISK; 1092 } else { 1093 minor = BLKIF_MINOR_EXT(info->vdevice); 1094 nr_parts = PARTS_PER_EXT_DISK; 1095 offset = minor / nr_parts; 1096 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 1097 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 1098 "emulated IDE disks,\n\t choose an xvd device name" 1099 "from xvde on\n", info->vdevice); 1100 } 1101 if (minor >> MINORBITS) { 1102 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 1103 info->vdevice, minor); 1104 return -ENODEV; 1105 } 1106 1107 if ((minor % nr_parts) == 0) 1108 nr_minors = nr_parts; 1109 1110 err = xlbd_reserve_minors(minor, nr_minors); 1111 if (err) 1112 return err; 1113 1114 memset(&info->tag_set, 0, sizeof(info->tag_set)); 1115 info->tag_set.ops = &blkfront_mq_ops; 1116 info->tag_set.nr_hw_queues = info->nr_rings; 1117 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) { 1118 /* 1119 * When indirect descriptior is not supported, the I/O request 1120 * will be split between multiple request in the ring. 1121 * To avoid problems when sending the request, divide by 1122 * 2 the depth of the queue. 1123 */ 1124 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2; 1125 } else 1126 info->tag_set.queue_depth = BLK_RING_SIZE(info); 1127 info->tag_set.numa_node = NUMA_NO_NODE; 1128 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; 1129 info->tag_set.cmd_size = sizeof(struct blkif_req); 1130 info->tag_set.driver_data = info; 1131 1132 err = blk_mq_alloc_tag_set(&info->tag_set); 1133 if (err) 1134 goto out_release_minors; 1135 1136 blkif_set_queue_limits(info, &lim); 1137 gd = blk_mq_alloc_disk(&info->tag_set, &lim, info); 1138 if (IS_ERR(gd)) { 1139 err = PTR_ERR(gd); 1140 goto out_free_tag_set; 1141 } 1142 blk_queue_flag_set(QUEUE_FLAG_VIRT, gd->queue); 1143 1144 strcpy(gd->disk_name, DEV_NAME); 1145 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 1146 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 1147 if (nr_minors > 1) 1148 *ptr = 0; 1149 else 1150 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 1151 "%d", minor & (nr_parts - 1)); 1152 1153 gd->major = XENVBD_MAJOR; 1154 gd->first_minor = minor; 1155 gd->minors = nr_minors; 1156 gd->fops = &xlvbd_block_fops; 1157 gd->private_data = info; 1158 set_capacity(gd, capacity); 1159 1160 info->rq = gd->queue; 1161 info->gd = gd; 1162 info->sector_size = sector_size; 1163 info->physical_sector_size = physical_sector_size; 1164 1165 xlvbd_flush(info); 1166 1167 if (info->vdisk_info & VDISK_READONLY) 1168 set_disk_ro(gd, 1); 1169 if (info->vdisk_info & VDISK_REMOVABLE) 1170 gd->flags |= GENHD_FL_REMOVABLE; 1171 1172 return 0; 1173 1174out_free_tag_set: 1175 blk_mq_free_tag_set(&info->tag_set); 1176out_release_minors: 1177 xlbd_release_minors(minor, nr_minors); 1178 return err; 1179} 1180 1181/* Already hold rinfo->ring_lock. */ 1182static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo) 1183{ 1184 if (!RING_FULL(&rinfo->ring)) 1185 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true); 1186} 1187 1188static void kick_pending_request_queues(struct blkfront_ring_info *rinfo) 1189{ 1190 unsigned long flags; 1191 1192 spin_lock_irqsave(&rinfo->ring_lock, flags); 1193 kick_pending_request_queues_locked(rinfo); 1194 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1195} 1196 1197static void blkif_restart_queue(struct work_struct *work) 1198{ 1199 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work); 1200 1201 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED) 1202 kick_pending_request_queues(rinfo); 1203} 1204 1205static void blkif_free_ring(struct blkfront_ring_info *rinfo) 1206{ 1207 struct grant *persistent_gnt, *n; 1208 struct blkfront_info *info = rinfo->dev_info; 1209 int i, j, segs; 1210 1211 /* 1212 * Remove indirect pages, this only happens when using indirect 1213 * descriptors but not persistent grants 1214 */ 1215 if (!list_empty(&rinfo->indirect_pages)) { 1216 struct page *indirect_page, *n; 1217 1218 BUG_ON(info->bounce); 1219 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 1220 list_del(&indirect_page->lru); 1221 __free_page(indirect_page); 1222 } 1223 } 1224 1225 /* Remove all persistent grants. */ 1226 if (!list_empty(&rinfo->grants)) { 1227 list_for_each_entry_safe(persistent_gnt, n, 1228 &rinfo->grants, node) { 1229 list_del(&persistent_gnt->node); 1230 if (persistent_gnt->gref != INVALID_GRANT_REF) { 1231 gnttab_end_foreign_access(persistent_gnt->gref, 1232 NULL); 1233 rinfo->persistent_gnts_c--; 1234 } 1235 if (info->bounce) 1236 __free_page(persistent_gnt->page); 1237 kfree(persistent_gnt); 1238 } 1239 } 1240 BUG_ON(rinfo->persistent_gnts_c != 0); 1241 1242 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1243 /* 1244 * Clear persistent grants present in requests already 1245 * on the shared ring 1246 */ 1247 if (!rinfo->shadow[i].request) 1248 goto free_shadow; 1249 1250 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 1251 rinfo->shadow[i].req.u.indirect.nr_segments : 1252 rinfo->shadow[i].req.u.rw.nr_segments; 1253 for (j = 0; j < segs; j++) { 1254 persistent_gnt = rinfo->shadow[i].grants_used[j]; 1255 gnttab_end_foreign_access(persistent_gnt->gref, NULL); 1256 if (info->bounce) 1257 __free_page(persistent_gnt->page); 1258 kfree(persistent_gnt); 1259 } 1260 1261 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT) 1262 /* 1263 * If this is not an indirect operation don't try to 1264 * free indirect segments 1265 */ 1266 goto free_shadow; 1267 1268 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 1269 persistent_gnt = rinfo->shadow[i].indirect_grants[j]; 1270 gnttab_end_foreign_access(persistent_gnt->gref, NULL); 1271 __free_page(persistent_gnt->page); 1272 kfree(persistent_gnt); 1273 } 1274 1275free_shadow: 1276 kvfree(rinfo->shadow[i].grants_used); 1277 rinfo->shadow[i].grants_used = NULL; 1278 kvfree(rinfo->shadow[i].indirect_grants); 1279 rinfo->shadow[i].indirect_grants = NULL; 1280 kvfree(rinfo->shadow[i].sg); 1281 rinfo->shadow[i].sg = NULL; 1282 } 1283 1284 /* No more gnttab callback work. */ 1285 gnttab_cancel_free_callback(&rinfo->callback); 1286 1287 /* Flush gnttab callback work. Must be done with no locks held. */ 1288 flush_work(&rinfo->work); 1289 1290 /* Free resources associated with old device channel. */ 1291 xenbus_teardown_ring((void **)&rinfo->ring.sring, info->nr_ring_pages, 1292 rinfo->ring_ref); 1293 1294 if (rinfo->irq) 1295 unbind_from_irqhandler(rinfo->irq, rinfo); 1296 rinfo->evtchn = rinfo->irq = 0; 1297} 1298 1299static void blkif_free(struct blkfront_info *info, int suspend) 1300{ 1301 unsigned int i; 1302 struct blkfront_ring_info *rinfo; 1303 1304 /* Prevent new requests being issued until we fix things up. */ 1305 info->connected = suspend ? 1306 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 1307 /* No more blkif_request(). */ 1308 if (info->rq) 1309 blk_mq_stop_hw_queues(info->rq); 1310 1311 for_each_rinfo(info, rinfo, i) 1312 blkif_free_ring(rinfo); 1313 1314 kvfree(info->rinfo); 1315 info->rinfo = NULL; 1316 info->nr_rings = 0; 1317} 1318 1319struct copy_from_grant { 1320 const struct blk_shadow *s; 1321 unsigned int grant_idx; 1322 unsigned int bvec_offset; 1323 char *bvec_data; 1324}; 1325 1326static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset, 1327 unsigned int len, void *data) 1328{ 1329 struct copy_from_grant *info = data; 1330 char *shared_data; 1331 /* Convenient aliases */ 1332 const struct blk_shadow *s = info->s; 1333 1334 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page); 1335 1336 memcpy(info->bvec_data + info->bvec_offset, 1337 shared_data + offset, len); 1338 1339 info->bvec_offset += len; 1340 info->grant_idx++; 1341 1342 kunmap_atomic(shared_data); 1343} 1344 1345static enum blk_req_status blkif_rsp_to_req_status(int rsp) 1346{ 1347 switch (rsp) 1348 { 1349 case BLKIF_RSP_OKAY: 1350 return REQ_DONE; 1351 case BLKIF_RSP_EOPNOTSUPP: 1352 return REQ_EOPNOTSUPP; 1353 case BLKIF_RSP_ERROR: 1354 default: 1355 return REQ_ERROR; 1356 } 1357} 1358 1359/* 1360 * Get the final status of the block request based on two ring response 1361 */ 1362static int blkif_get_final_status(enum blk_req_status s1, 1363 enum blk_req_status s2) 1364{ 1365 BUG_ON(s1 < REQ_DONE); 1366 BUG_ON(s2 < REQ_DONE); 1367 1368 if (s1 == REQ_ERROR || s2 == REQ_ERROR) 1369 return BLKIF_RSP_ERROR; 1370 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP) 1371 return BLKIF_RSP_EOPNOTSUPP; 1372 return BLKIF_RSP_OKAY; 1373} 1374 1375/* 1376 * Return values: 1377 * 1 response processed. 1378 * 0 missing further responses. 1379 * -1 error while processing. 1380 */ 1381static int blkif_completion(unsigned long *id, 1382 struct blkfront_ring_info *rinfo, 1383 struct blkif_response *bret) 1384{ 1385 int i = 0; 1386 struct scatterlist *sg; 1387 int num_sg, num_grant; 1388 struct blkfront_info *info = rinfo->dev_info; 1389 struct blk_shadow *s = &rinfo->shadow[*id]; 1390 struct copy_from_grant data = { 1391 .grant_idx = 0, 1392 }; 1393 1394 num_grant = s->req.operation == BLKIF_OP_INDIRECT ? 1395 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1396 1397 /* The I/O request may be split in two. */ 1398 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) { 1399 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id]; 1400 1401 /* Keep the status of the current response in shadow. */ 1402 s->status = blkif_rsp_to_req_status(bret->status); 1403 1404 /* Wait the second response if not yet here. */ 1405 if (s2->status < REQ_DONE) 1406 return 0; 1407 1408 bret->status = blkif_get_final_status(s->status, 1409 s2->status); 1410 1411 /* 1412 * All the grants is stored in the first shadow in order 1413 * to make the completion code simpler. 1414 */ 1415 num_grant += s2->req.u.rw.nr_segments; 1416 1417 /* 1418 * The two responses may not come in order. Only the 1419 * first request will store the scatter-gather list. 1420 */ 1421 if (s2->num_sg != 0) { 1422 /* Update "id" with the ID of the first response. */ 1423 *id = s->associated_id; 1424 s = s2; 1425 } 1426 1427 /* 1428 * We don't need anymore the second request, so recycling 1429 * it now. 1430 */ 1431 if (add_id_to_freelist(rinfo, s->associated_id)) 1432 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n", 1433 info->gd->disk_name, s->associated_id); 1434 } 1435 1436 data.s = s; 1437 num_sg = s->num_sg; 1438 1439 if (bret->operation == BLKIF_OP_READ && info->bounce) { 1440 for_each_sg(s->sg, sg, num_sg, i) { 1441 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1442 1443 data.bvec_offset = sg->offset; 1444 data.bvec_data = kmap_atomic(sg_page(sg)); 1445 1446 gnttab_foreach_grant_in_range(sg_page(sg), 1447 sg->offset, 1448 sg->length, 1449 blkif_copy_from_grant, 1450 &data); 1451 1452 kunmap_atomic(data.bvec_data); 1453 } 1454 } 1455 /* Add the persistent grant into the list of free grants */ 1456 for (i = 0; i < num_grant; i++) { 1457 if (!gnttab_try_end_foreign_access(s->grants_used[i]->gref)) { 1458 /* 1459 * If the grant is still mapped by the backend (the 1460 * backend has chosen to make this grant persistent) 1461 * we add it at the head of the list, so it will be 1462 * reused first. 1463 */ 1464 if (!info->feature_persistent) { 1465 pr_alert("backed has not unmapped grant: %u\n", 1466 s->grants_used[i]->gref); 1467 return -1; 1468 } 1469 list_add(&s->grants_used[i]->node, &rinfo->grants); 1470 rinfo->persistent_gnts_c++; 1471 } else { 1472 /* 1473 * If the grant is not mapped by the backend we add it 1474 * to the tail of the list, so it will not be picked 1475 * again unless we run out of persistent grants. 1476 */ 1477 s->grants_used[i]->gref = INVALID_GRANT_REF; 1478 list_add_tail(&s->grants_used[i]->node, &rinfo->grants); 1479 } 1480 } 1481 if (s->req.operation == BLKIF_OP_INDIRECT) { 1482 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) { 1483 if (!gnttab_try_end_foreign_access(s->indirect_grants[i]->gref)) { 1484 if (!info->feature_persistent) { 1485 pr_alert("backed has not unmapped grant: %u\n", 1486 s->indirect_grants[i]->gref); 1487 return -1; 1488 } 1489 list_add(&s->indirect_grants[i]->node, &rinfo->grants); 1490 rinfo->persistent_gnts_c++; 1491 } else { 1492 struct page *indirect_page; 1493 1494 /* 1495 * Add the used indirect page back to the list of 1496 * available pages for indirect grefs. 1497 */ 1498 if (!info->bounce) { 1499 indirect_page = s->indirect_grants[i]->page; 1500 list_add(&indirect_page->lru, &rinfo->indirect_pages); 1501 } 1502 s->indirect_grants[i]->gref = INVALID_GRANT_REF; 1503 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants); 1504 } 1505 } 1506 } 1507 1508 return 1; 1509} 1510 1511static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1512{ 1513 struct request *req; 1514 struct blkif_response bret; 1515 RING_IDX i, rp; 1516 unsigned long flags; 1517 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id; 1518 struct blkfront_info *info = rinfo->dev_info; 1519 unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS; 1520 1521 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { 1522 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS); 1523 return IRQ_HANDLED; 1524 } 1525 1526 spin_lock_irqsave(&rinfo->ring_lock, flags); 1527 again: 1528 rp = READ_ONCE(rinfo->ring.sring->rsp_prod); 1529 virt_rmb(); /* Ensure we see queued responses up to 'rp'. */ 1530 if (RING_RESPONSE_PROD_OVERFLOW(&rinfo->ring, rp)) { 1531 pr_alert("%s: illegal number of responses %u\n", 1532 info->gd->disk_name, rp - rinfo->ring.rsp_cons); 1533 goto err; 1534 } 1535 1536 for (i = rinfo->ring.rsp_cons; i != rp; i++) { 1537 unsigned long id; 1538 unsigned int op; 1539 1540 eoiflag = 0; 1541 1542 RING_COPY_RESPONSE(&rinfo->ring, i, &bret); 1543 id = bret.id; 1544 1545 /* 1546 * The backend has messed up and given us an id that we would 1547 * never have given to it (we stamp it up to BLK_RING_SIZE - 1548 * look in get_id_from_freelist. 1549 */ 1550 if (id >= BLK_RING_SIZE(info)) { 1551 pr_alert("%s: response has incorrect id (%ld)\n", 1552 info->gd->disk_name, id); 1553 goto err; 1554 } 1555 if (rinfo->shadow[id].status != REQ_WAITING) { 1556 pr_alert("%s: response references no pending request\n", 1557 info->gd->disk_name); 1558 goto err; 1559 } 1560 1561 rinfo->shadow[id].status = REQ_PROCESSING; 1562 req = rinfo->shadow[id].request; 1563 1564 op = rinfo->shadow[id].req.operation; 1565 if (op == BLKIF_OP_INDIRECT) 1566 op = rinfo->shadow[id].req.u.indirect.indirect_op; 1567 if (bret.operation != op) { 1568 pr_alert("%s: response has wrong operation (%u instead of %u)\n", 1569 info->gd->disk_name, bret.operation, op); 1570 goto err; 1571 } 1572 1573 if (bret.operation != BLKIF_OP_DISCARD) { 1574 int ret; 1575 1576 /* 1577 * We may need to wait for an extra response if the 1578 * I/O request is split in 2 1579 */ 1580 ret = blkif_completion(&id, rinfo, &bret); 1581 if (!ret) 1582 continue; 1583 if (unlikely(ret < 0)) 1584 goto err; 1585 } 1586 1587 if (add_id_to_freelist(rinfo, id)) { 1588 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1589 info->gd->disk_name, op_name(bret.operation), id); 1590 continue; 1591 } 1592 1593 if (bret.status == BLKIF_RSP_OKAY) 1594 blkif_req(req)->error = BLK_STS_OK; 1595 else 1596 blkif_req(req)->error = BLK_STS_IOERR; 1597 1598 switch (bret.operation) { 1599 case BLKIF_OP_DISCARD: 1600 if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) { 1601 struct request_queue *rq = info->rq; 1602 1603 pr_warn_ratelimited("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_max_discard_sectors(rq, 0); 1609 blk_queue_max_secure_erase_sectors(rq, 0); 1610 } 1611 break; 1612 case BLKIF_OP_FLUSH_DISKCACHE: 1613 case BLKIF_OP_WRITE_BARRIER: 1614 if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) { 1615 pr_warn_ratelimited("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 pr_warn_ratelimited("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 fallthrough; 1633 case BLKIF_OP_READ: 1634 case BLKIF_OP_WRITE: 1635 if (unlikely(bret.status != BLKIF_RSP_OKAY)) 1636 dev_dbg_ratelimited(&info->xbdev->dev, 1637 "Bad return from blkdev data request: %#x\n", 1638 bret.status); 1639 1640 break; 1641 default: 1642 BUG(); 1643 } 1644 1645 if (likely(!blk_should_fake_timeout(req->q))) 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 xen_irq_lateeoi(irq, eoiflag); 1664 1665 return IRQ_HANDLED; 1666 1667 err: 1668 info->connected = BLKIF_STATE_ERROR; 1669 1670 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1671 1672 /* No EOI in order to avoid further interrupts. */ 1673 1674 pr_alert("%s disabled for further use\n", info->gd->disk_name); 1675 return IRQ_HANDLED; 1676} 1677 1678 1679static int setup_blkring(struct xenbus_device *dev, 1680 struct blkfront_ring_info *rinfo) 1681{ 1682 struct blkif_sring *sring; 1683 int err; 1684 struct blkfront_info *info = rinfo->dev_info; 1685 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE; 1686 1687 err = xenbus_setup_ring(dev, GFP_NOIO, (void **)&sring, 1688 info->nr_ring_pages, rinfo->ring_ref); 1689 if (err) 1690 goto fail; 1691 1692 XEN_FRONT_RING_INIT(&rinfo->ring, sring, ring_size); 1693 1694 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn); 1695 if (err) 1696 goto fail; 1697 1698 err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt, 1699 0, "blkif", rinfo); 1700 if (err <= 0) { 1701 xenbus_dev_fatal(dev, err, 1702 "bind_evtchn_to_irqhandler failed"); 1703 goto fail; 1704 } 1705 rinfo->irq = err; 1706 1707 return 0; 1708fail: 1709 blkif_free(info, 0); 1710 return err; 1711} 1712 1713/* 1714 * Write out per-ring/queue nodes including ring-ref and event-channel, and each 1715 * ring buffer may have multi pages depending on ->nr_ring_pages. 1716 */ 1717static int write_per_ring_nodes(struct xenbus_transaction xbt, 1718 struct blkfront_ring_info *rinfo, const char *dir) 1719{ 1720 int err; 1721 unsigned int i; 1722 const char *message = NULL; 1723 struct blkfront_info *info = rinfo->dev_info; 1724 1725 if (info->nr_ring_pages == 1) { 1726 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]); 1727 if (err) { 1728 message = "writing ring-ref"; 1729 goto abort_transaction; 1730 } 1731 } else { 1732 for (i = 0; i < info->nr_ring_pages; i++) { 1733 char ring_ref_name[RINGREF_NAME_LEN]; 1734 1735 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 1736 err = xenbus_printf(xbt, dir, ring_ref_name, 1737 "%u", rinfo->ring_ref[i]); 1738 if (err) { 1739 message = "writing ring-ref"; 1740 goto abort_transaction; 1741 } 1742 } 1743 } 1744 1745 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn); 1746 if (err) { 1747 message = "writing event-channel"; 1748 goto abort_transaction; 1749 } 1750 1751 return 0; 1752 1753abort_transaction: 1754 xenbus_transaction_end(xbt, 1); 1755 if (message) 1756 xenbus_dev_fatal(info->xbdev, err, "%s", message); 1757 1758 return err; 1759} 1760 1761/* Enable the persistent grants feature. */ 1762static bool feature_persistent = true; 1763module_param(feature_persistent, bool, 0644); 1764MODULE_PARM_DESC(feature_persistent, 1765 "Enables the persistent grants feature"); 1766 1767/* Common code used when first setting up, and when resuming. */ 1768static int talk_to_blkback(struct xenbus_device *dev, 1769 struct blkfront_info *info) 1770{ 1771 const char *message = NULL; 1772 struct xenbus_transaction xbt; 1773 int err; 1774 unsigned int i, max_page_order; 1775 unsigned int ring_page_order; 1776 struct blkfront_ring_info *rinfo; 1777 1778 if (!info) 1779 return -ENODEV; 1780 1781 /* Check if backend is trusted. */ 1782 info->bounce = !xen_blkif_trusted || 1783 !xenbus_read_unsigned(dev->nodename, "trusted", 1); 1784 1785 max_page_order = xenbus_read_unsigned(info->xbdev->otherend, 1786 "max-ring-page-order", 0); 1787 ring_page_order = min(xen_blkif_max_ring_order, max_page_order); 1788 info->nr_ring_pages = 1 << ring_page_order; 1789 1790 err = negotiate_mq(info); 1791 if (err) 1792 goto destroy_blkring; 1793 1794 for_each_rinfo(info, rinfo, i) { 1795 /* Create shared ring, alloc event channel. */ 1796 err = setup_blkring(dev, rinfo); 1797 if (err) 1798 goto destroy_blkring; 1799 } 1800 1801again: 1802 err = xenbus_transaction_start(&xbt); 1803 if (err) { 1804 xenbus_dev_fatal(dev, err, "starting transaction"); 1805 goto destroy_blkring; 1806 } 1807 1808 if (info->nr_ring_pages > 1) { 1809 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u", 1810 ring_page_order); 1811 if (err) { 1812 message = "writing ring-page-order"; 1813 goto abort_transaction; 1814 } 1815 } 1816 1817 /* We already got the number of queues/rings in _probe */ 1818 if (info->nr_rings == 1) { 1819 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename); 1820 if (err) 1821 goto destroy_blkring; 1822 } else { 1823 char *path; 1824 size_t pathsize; 1825 1826 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u", 1827 info->nr_rings); 1828 if (err) { 1829 message = "writing multi-queue-num-queues"; 1830 goto abort_transaction; 1831 } 1832 1833 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN; 1834 path = kmalloc(pathsize, GFP_KERNEL); 1835 if (!path) { 1836 err = -ENOMEM; 1837 message = "ENOMEM while writing ring references"; 1838 goto abort_transaction; 1839 } 1840 1841 for_each_rinfo(info, rinfo, i) { 1842 memset(path, 0, pathsize); 1843 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i); 1844 err = write_per_ring_nodes(xbt, rinfo, path); 1845 if (err) { 1846 kfree(path); 1847 goto destroy_blkring; 1848 } 1849 } 1850 kfree(path); 1851 } 1852 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1853 XEN_IO_PROTO_ABI_NATIVE); 1854 if (err) { 1855 message = "writing protocol"; 1856 goto abort_transaction; 1857 } 1858 info->feature_persistent_parm = feature_persistent; 1859 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1860 info->feature_persistent_parm); 1861 if (err) 1862 dev_warn(&dev->dev, 1863 "writing persistent grants feature to xenbus"); 1864 1865 err = xenbus_transaction_end(xbt, 0); 1866 if (err) { 1867 if (err == -EAGAIN) 1868 goto again; 1869 xenbus_dev_fatal(dev, err, "completing transaction"); 1870 goto destroy_blkring; 1871 } 1872 1873 for_each_rinfo(info, rinfo, i) { 1874 unsigned int j; 1875 1876 for (j = 0; j < BLK_RING_SIZE(info); j++) 1877 rinfo->shadow[j].req.u.rw.id = j + 1; 1878 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 1879 } 1880 xenbus_switch_state(dev, XenbusStateInitialised); 1881 1882 return 0; 1883 1884 abort_transaction: 1885 xenbus_transaction_end(xbt, 1); 1886 if (message) 1887 xenbus_dev_fatal(dev, err, "%s", message); 1888 destroy_blkring: 1889 blkif_free(info, 0); 1890 return err; 1891} 1892 1893static int negotiate_mq(struct blkfront_info *info) 1894{ 1895 unsigned int backend_max_queues; 1896 unsigned int i; 1897 struct blkfront_ring_info *rinfo; 1898 1899 BUG_ON(info->nr_rings); 1900 1901 /* Check if backend supports multiple queues. */ 1902 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend, 1903 "multi-queue-max-queues", 1); 1904 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues); 1905 /* We need at least one ring. */ 1906 if (!info->nr_rings) 1907 info->nr_rings = 1; 1908 1909 info->rinfo_size = struct_size(info->rinfo, shadow, 1910 BLK_RING_SIZE(info)); 1911 info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL); 1912 if (!info->rinfo) { 1913 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure"); 1914 info->nr_rings = 0; 1915 return -ENOMEM; 1916 } 1917 1918 for_each_rinfo(info, rinfo, i) { 1919 INIT_LIST_HEAD(&rinfo->indirect_pages); 1920 INIT_LIST_HEAD(&rinfo->grants); 1921 rinfo->dev_info = info; 1922 INIT_WORK(&rinfo->work, blkif_restart_queue); 1923 spin_lock_init(&rinfo->ring_lock); 1924 } 1925 return 0; 1926} 1927 1928/* 1929 * Entry point to this code when a new device is created. Allocate the basic 1930 * structures and the ring buffer for communication with the backend, and 1931 * inform the backend of the appropriate details for those. Switch to 1932 * Initialised state. 1933 */ 1934static int blkfront_probe(struct xenbus_device *dev, 1935 const struct xenbus_device_id *id) 1936{ 1937 int err, vdevice; 1938 struct blkfront_info *info; 1939 1940 /* FIXME: Use dynamic device id if this is not set. */ 1941 err = xenbus_scanf(XBT_NIL, dev->nodename, 1942 "virtual-device", "%i", &vdevice); 1943 if (err != 1) { 1944 /* go looking in the extended area instead */ 1945 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1946 "%i", &vdevice); 1947 if (err != 1) { 1948 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1949 return err; 1950 } 1951 } 1952 1953 if (xen_hvm_domain()) { 1954 char *type; 1955 int len; 1956 /* no unplug has been done: do not hook devices != xen vbds */ 1957 if (xen_has_pv_and_legacy_disk_devices()) { 1958 int major; 1959 1960 if (!VDEV_IS_EXTENDED(vdevice)) 1961 major = BLKIF_MAJOR(vdevice); 1962 else 1963 major = XENVBD_MAJOR; 1964 1965 if (major != XENVBD_MAJOR) { 1966 printk(KERN_INFO 1967 "%s: HVM does not support vbd %d as xen block device\n", 1968 __func__, vdevice); 1969 return -ENODEV; 1970 } 1971 } 1972 /* do not create a PV cdrom device if we are an HVM guest */ 1973 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1974 if (IS_ERR(type)) 1975 return -ENODEV; 1976 if (strncmp(type, "cdrom", 5) == 0) { 1977 kfree(type); 1978 return -ENODEV; 1979 } 1980 kfree(type); 1981 } 1982 info = kzalloc(sizeof(*info), GFP_KERNEL); 1983 if (!info) { 1984 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1985 return -ENOMEM; 1986 } 1987 1988 info->xbdev = dev; 1989 1990 mutex_init(&info->mutex); 1991 info->vdevice = vdevice; 1992 info->connected = BLKIF_STATE_DISCONNECTED; 1993 1994 /* Front end dir is a number, which is used as the id. */ 1995 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1996 dev_set_drvdata(&dev->dev, info); 1997 1998 mutex_lock(&blkfront_mutex); 1999 list_add(&info->info_list, &info_list); 2000 mutex_unlock(&blkfront_mutex); 2001 2002 return 0; 2003} 2004 2005static int blkif_recover(struct blkfront_info *info) 2006{ 2007 struct queue_limits lim; 2008 unsigned int r_index; 2009 struct request *req, *n; 2010 int rc; 2011 struct bio *bio; 2012 struct blkfront_ring_info *rinfo; 2013 2014 lim = queue_limits_start_update(info->rq); 2015 blkfront_gather_backend_features(info); 2016 blkif_set_queue_limits(info, &lim); 2017 rc = queue_limits_commit_update(info->rq, &lim); 2018 if (rc) 2019 return rc; 2020 2021 for_each_rinfo(info, rinfo, r_index) { 2022 rc = blkfront_setup_indirect(rinfo); 2023 if (rc) 2024 return rc; 2025 } 2026 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2027 2028 /* Now safe for us to use the shared ring */ 2029 info->connected = BLKIF_STATE_CONNECTED; 2030 2031 for_each_rinfo(info, rinfo, r_index) { 2032 /* Kick any other new requests queued since we resumed */ 2033 kick_pending_request_queues(rinfo); 2034 } 2035 2036 list_for_each_entry_safe(req, n, &info->requests, queuelist) { 2037 /* Requeue pending requests (flush or discard) */ 2038 list_del_init(&req->queuelist); 2039 BUG_ON(req->nr_phys_segments > 2040 (info->max_indirect_segments ? : 2041 BLKIF_MAX_SEGMENTS_PER_REQUEST)); 2042 blk_mq_requeue_request(req, false); 2043 } 2044 blk_mq_start_stopped_hw_queues(info->rq, true); 2045 blk_mq_kick_requeue_list(info->rq); 2046 2047 while ((bio = bio_list_pop(&info->bio_list)) != NULL) { 2048 /* Traverse the list of pending bios and re-queue them */ 2049 submit_bio(bio); 2050 } 2051 2052 return 0; 2053} 2054 2055/* 2056 * We are reconnecting to the backend, due to a suspend/resume, or a backend 2057 * driver restart. We tear down our blkif structure and recreate it, but 2058 * leave the device-layer structures intact so that this is transparent to the 2059 * rest of the kernel. 2060 */ 2061static int blkfront_resume(struct xenbus_device *dev) 2062{ 2063 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2064 int err = 0; 2065 unsigned int i, j; 2066 struct blkfront_ring_info *rinfo; 2067 2068 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 2069 2070 bio_list_init(&info->bio_list); 2071 INIT_LIST_HEAD(&info->requests); 2072 for_each_rinfo(info, rinfo, i) { 2073 struct bio_list merge_bio; 2074 struct blk_shadow *shadow = rinfo->shadow; 2075 2076 for (j = 0; j < BLK_RING_SIZE(info); j++) { 2077 /* Not in use? */ 2078 if (!shadow[j].request) 2079 continue; 2080 2081 /* 2082 * Get the bios in the request so we can re-queue them. 2083 */ 2084 if (req_op(shadow[j].request) == REQ_OP_FLUSH || 2085 req_op(shadow[j].request) == REQ_OP_DISCARD || 2086 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE || 2087 shadow[j].request->cmd_flags & REQ_FUA) { 2088 /* 2089 * Flush operations don't contain bios, so 2090 * we need to requeue the whole request 2091 * 2092 * XXX: but this doesn't make any sense for a 2093 * write with the FUA flag set.. 2094 */ 2095 list_add(&shadow[j].request->queuelist, &info->requests); 2096 continue; 2097 } 2098 merge_bio.head = shadow[j].request->bio; 2099 merge_bio.tail = shadow[j].request->biotail; 2100 bio_list_merge(&info->bio_list, &merge_bio); 2101 shadow[j].request->bio = NULL; 2102 blk_mq_end_request(shadow[j].request, BLK_STS_OK); 2103 } 2104 } 2105 2106 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 2107 2108 err = talk_to_blkback(dev, info); 2109 if (!err) 2110 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings); 2111 2112 /* 2113 * We have to wait for the backend to switch to 2114 * connected state, since we want to read which 2115 * features it supports. 2116 */ 2117 2118 return err; 2119} 2120 2121static void blkfront_closing(struct blkfront_info *info) 2122{ 2123 struct xenbus_device *xbdev = info->xbdev; 2124 struct blkfront_ring_info *rinfo; 2125 unsigned int i; 2126 2127 if (xbdev->state == XenbusStateClosing) 2128 return; 2129 2130 /* No more blkif_request(). */ 2131 if (info->rq && info->gd) { 2132 blk_mq_stop_hw_queues(info->rq); 2133 blk_mark_disk_dead(info->gd); 2134 } 2135 2136 for_each_rinfo(info, rinfo, i) { 2137 /* No more gnttab callback work. */ 2138 gnttab_cancel_free_callback(&rinfo->callback); 2139 2140 /* Flush gnttab callback work. Must be done with no locks held. */ 2141 flush_work(&rinfo->work); 2142 } 2143 2144 xenbus_frontend_closed(xbdev); 2145} 2146 2147static void blkfront_setup_discard(struct blkfront_info *info) 2148{ 2149 info->feature_discard = 1; 2150 info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend, 2151 "discard-granularity", 2152 0); 2153 info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend, 2154 "discard-alignment", 0); 2155 info->feature_secdiscard = 2156 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure", 2157 0); 2158} 2159 2160static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo) 2161{ 2162 unsigned int psegs, grants, memflags; 2163 int err, i; 2164 struct blkfront_info *info = rinfo->dev_info; 2165 2166 memflags = memalloc_noio_save(); 2167 2168 if (info->max_indirect_segments == 0) { 2169 if (!HAS_EXTRA_REQ) 2170 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2171 else { 2172 /* 2173 * When an extra req is required, the maximum 2174 * grants supported is related to the size of the 2175 * Linux block segment. 2176 */ 2177 grants = GRANTS_PER_PSEG; 2178 } 2179 } 2180 else 2181 grants = info->max_indirect_segments; 2182 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG); 2183 2184 err = fill_grant_buffer(rinfo, 2185 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info)); 2186 if (err) 2187 goto out_of_memory; 2188 2189 if (!info->bounce && info->max_indirect_segments) { 2190 /* 2191 * We are using indirect descriptors but don't have a bounce 2192 * buffer, we need to allocate a set of pages that can be 2193 * used for mapping indirect grefs 2194 */ 2195 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info); 2196 2197 BUG_ON(!list_empty(&rinfo->indirect_pages)); 2198 for (i = 0; i < num; i++) { 2199 struct page *indirect_page = alloc_page(GFP_KERNEL | 2200 __GFP_ZERO); 2201 if (!indirect_page) 2202 goto out_of_memory; 2203 list_add(&indirect_page->lru, &rinfo->indirect_pages); 2204 } 2205 } 2206 2207 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2208 rinfo->shadow[i].grants_used = 2209 kvcalloc(grants, 2210 sizeof(rinfo->shadow[i].grants_used[0]), 2211 GFP_KERNEL); 2212 rinfo->shadow[i].sg = kvcalloc(psegs, 2213 sizeof(rinfo->shadow[i].sg[0]), 2214 GFP_KERNEL); 2215 if (info->max_indirect_segments) 2216 rinfo->shadow[i].indirect_grants = 2217 kvcalloc(INDIRECT_GREFS(grants), 2218 sizeof(rinfo->shadow[i].indirect_grants[0]), 2219 GFP_KERNEL); 2220 if ((rinfo->shadow[i].grants_used == NULL) || 2221 (rinfo->shadow[i].sg == NULL) || 2222 (info->max_indirect_segments && 2223 (rinfo->shadow[i].indirect_grants == NULL))) 2224 goto out_of_memory; 2225 sg_init_table(rinfo->shadow[i].sg, psegs); 2226 } 2227 2228 memalloc_noio_restore(memflags); 2229 2230 return 0; 2231 2232out_of_memory: 2233 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2234 kvfree(rinfo->shadow[i].grants_used); 2235 rinfo->shadow[i].grants_used = NULL; 2236 kvfree(rinfo->shadow[i].sg); 2237 rinfo->shadow[i].sg = NULL; 2238 kvfree(rinfo->shadow[i].indirect_grants); 2239 rinfo->shadow[i].indirect_grants = NULL; 2240 } 2241 if (!list_empty(&rinfo->indirect_pages)) { 2242 struct page *indirect_page, *n; 2243 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 2244 list_del(&indirect_page->lru); 2245 __free_page(indirect_page); 2246 } 2247 } 2248 2249 memalloc_noio_restore(memflags); 2250 2251 return -ENOMEM; 2252} 2253 2254/* 2255 * Gather all backend feature-* 2256 */ 2257static void blkfront_gather_backend_features(struct blkfront_info *info) 2258{ 2259 unsigned int indirect_segments; 2260 2261 info->feature_flush = 0; 2262 info->feature_fua = 0; 2263 2264 /* 2265 * If there's no "feature-barrier" defined, then it means 2266 * we're dealing with a very old backend which writes 2267 * synchronously; nothing to do. 2268 * 2269 * If there are barriers, then we use flush. 2270 */ 2271 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) { 2272 info->feature_flush = 1; 2273 info->feature_fua = 1; 2274 } 2275 2276 /* 2277 * And if there is "feature-flush-cache" use that above 2278 * barriers. 2279 */ 2280 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache", 2281 0)) { 2282 info->feature_flush = 1; 2283 info->feature_fua = 0; 2284 } 2285 2286 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) 2287 blkfront_setup_discard(info); 2288 2289 if (info->feature_persistent_parm) 2290 info->feature_persistent = 2291 !!xenbus_read_unsigned(info->xbdev->otherend, 2292 "feature-persistent", 0); 2293 if (info->feature_persistent) 2294 info->bounce = true; 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 if (info->feature_persistent) { 2305 mutex_lock(&blkfront_mutex); 2306 schedule_delayed_work(&blkfront_work, HZ * 10); 2307 mutex_unlock(&blkfront_mutex); 2308 } 2309} 2310 2311/* 2312 * Invoked when the backend is finally 'ready' (and has told produced 2313 * the details about the physical device - #sectors, size, etc). 2314 */ 2315static void blkfront_connect(struct blkfront_info *info) 2316{ 2317 unsigned long long sectors; 2318 unsigned long sector_size; 2319 unsigned int physical_sector_size; 2320 int err, i; 2321 struct blkfront_ring_info *rinfo; 2322 2323 switch (info->connected) { 2324 case BLKIF_STATE_CONNECTED: 2325 /* 2326 * Potentially, the back-end may be signalling 2327 * a capacity change; update the capacity. 2328 */ 2329 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2330 "sectors", "%Lu", §ors); 2331 if (XENBUS_EXIST_ERR(err)) 2332 return; 2333 printk(KERN_INFO "Setting capacity to %Lu\n", 2334 sectors); 2335 set_capacity_and_notify(info->gd, sectors); 2336 2337 return; 2338 case BLKIF_STATE_SUSPENDED: 2339 /* 2340 * If we are recovering from suspension, we need to wait 2341 * for the backend to announce it's features before 2342 * reconnecting, at least we need to know if the backend 2343 * supports indirect descriptors, and how many. 2344 */ 2345 blkif_recover(info); 2346 return; 2347 2348 default: 2349 break; 2350 } 2351 2352 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 2353 __func__, info->xbdev->otherend); 2354 2355 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2356 "sectors", "%llu", §ors, 2357 "info", "%u", &info->vdisk_info, 2358 "sector-size", "%lu", §or_size, 2359 NULL); 2360 if (err) { 2361 xenbus_dev_fatal(info->xbdev, err, 2362 "reading backend fields at %s", 2363 info->xbdev->otherend); 2364 return; 2365 } 2366 2367 /* 2368 * physical-sector-size is a newer field, so old backends may not 2369 * provide this. Assume physical sector size to be the same as 2370 * sector_size in that case. 2371 */ 2372 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend, 2373 "physical-sector-size", 2374 sector_size); 2375 blkfront_gather_backend_features(info); 2376 for_each_rinfo(info, rinfo, i) { 2377 err = blkfront_setup_indirect(rinfo); 2378 if (err) { 2379 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 2380 info->xbdev->otherend); 2381 blkif_free(info, 0); 2382 break; 2383 } 2384 } 2385 2386 err = xlvbd_alloc_gendisk(sectors, info, sector_size, 2387 physical_sector_size); 2388 if (err) { 2389 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 2390 info->xbdev->otherend); 2391 goto fail; 2392 } 2393 2394 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2395 2396 /* Kick pending requests. */ 2397 info->connected = BLKIF_STATE_CONNECTED; 2398 for_each_rinfo(info, rinfo, i) 2399 kick_pending_request_queues(rinfo); 2400 2401 err = device_add_disk(&info->xbdev->dev, info->gd, NULL); 2402 if (err) { 2403 put_disk(info->gd); 2404 blk_mq_free_tag_set(&info->tag_set); 2405 info->rq = NULL; 2406 goto fail; 2407 } 2408 2409 info->is_ready = 1; 2410 return; 2411 2412fail: 2413 blkif_free(info, 0); 2414 return; 2415} 2416 2417/* 2418 * Callback received when the backend's state changes. 2419 */ 2420static void blkback_changed(struct xenbus_device *dev, 2421 enum xenbus_state backend_state) 2422{ 2423 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2424 2425 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 2426 2427 switch (backend_state) { 2428 case XenbusStateInitWait: 2429 if (dev->state != XenbusStateInitialising) 2430 break; 2431 if (talk_to_blkback(dev, info)) 2432 break; 2433 break; 2434 case XenbusStateInitialising: 2435 case XenbusStateInitialised: 2436 case XenbusStateReconfiguring: 2437 case XenbusStateReconfigured: 2438 case XenbusStateUnknown: 2439 break; 2440 2441 case XenbusStateConnected: 2442 /* 2443 * talk_to_blkback sets state to XenbusStateInitialised 2444 * and blkfront_connect sets it to XenbusStateConnected 2445 * (if connection went OK). 2446 * 2447 * If the backend (or toolstack) decides to poke at backend 2448 * state (and re-trigger the watch by setting the state repeatedly 2449 * to XenbusStateConnected (4)) we need to deal with this. 2450 * This is allowed as this is used to communicate to the guest 2451 * that the size of disk has changed! 2452 */ 2453 if ((dev->state != XenbusStateInitialised) && 2454 (dev->state != XenbusStateConnected)) { 2455 if (talk_to_blkback(dev, info)) 2456 break; 2457 } 2458 2459 blkfront_connect(info); 2460 break; 2461 2462 case XenbusStateClosed: 2463 if (dev->state == XenbusStateClosed) 2464 break; 2465 fallthrough; 2466 case XenbusStateClosing: 2467 blkfront_closing(info); 2468 break; 2469 } 2470} 2471 2472static void blkfront_remove(struct xenbus_device *xbdev) 2473{ 2474 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 2475 2476 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 2477 2478 if (info->gd) 2479 del_gendisk(info->gd); 2480 2481 mutex_lock(&blkfront_mutex); 2482 list_del(&info->info_list); 2483 mutex_unlock(&blkfront_mutex); 2484 2485 blkif_free(info, 0); 2486 if (info->gd) { 2487 xlbd_release_minors(info->gd->first_minor, info->gd->minors); 2488 put_disk(info->gd); 2489 blk_mq_free_tag_set(&info->tag_set); 2490 } 2491 2492 kfree(info); 2493} 2494 2495static int blkfront_is_ready(struct xenbus_device *dev) 2496{ 2497 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2498 2499 return info->is_ready && info->xbdev; 2500} 2501 2502static const struct block_device_operations xlvbd_block_fops = 2503{ 2504 .owner = THIS_MODULE, 2505 .getgeo = blkif_getgeo, 2506 .ioctl = blkif_ioctl, 2507 .compat_ioctl = blkdev_compat_ptr_ioctl, 2508}; 2509 2510 2511static const struct xenbus_device_id blkfront_ids[] = { 2512 { "vbd" }, 2513 { "" } 2514}; 2515 2516static struct xenbus_driver blkfront_driver = { 2517 .ids = blkfront_ids, 2518 .probe = blkfront_probe, 2519 .remove = blkfront_remove, 2520 .resume = blkfront_resume, 2521 .otherend_changed = blkback_changed, 2522 .is_ready = blkfront_is_ready, 2523}; 2524 2525static void purge_persistent_grants(struct blkfront_info *info) 2526{ 2527 unsigned int i; 2528 unsigned long flags; 2529 struct blkfront_ring_info *rinfo; 2530 2531 for_each_rinfo(info, rinfo, i) { 2532 struct grant *gnt_list_entry, *tmp; 2533 LIST_HEAD(grants); 2534 2535 spin_lock_irqsave(&rinfo->ring_lock, flags); 2536 2537 if (rinfo->persistent_gnts_c == 0) { 2538 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 2539 continue; 2540 } 2541 2542 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants, 2543 node) { 2544 if (gnt_list_entry->gref == INVALID_GRANT_REF || 2545 !gnttab_try_end_foreign_access(gnt_list_entry->gref)) 2546 continue; 2547 2548 list_del(&gnt_list_entry->node); 2549 rinfo->persistent_gnts_c--; 2550 gnt_list_entry->gref = INVALID_GRANT_REF; 2551 list_add_tail(&gnt_list_entry->node, &grants); 2552 } 2553 2554 list_splice_tail(&grants, &rinfo->grants); 2555 2556 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 2557 } 2558} 2559 2560static void blkfront_delay_work(struct work_struct *work) 2561{ 2562 struct blkfront_info *info; 2563 bool need_schedule_work = false; 2564 2565 /* 2566 * Note that when using bounce buffers but not persistent grants 2567 * there's no need to run blkfront_delay_work because grants are 2568 * revoked in blkif_completion or else an error is reported and the 2569 * connection is closed. 2570 */ 2571 2572 mutex_lock(&blkfront_mutex); 2573 2574 list_for_each_entry(info, &info_list, info_list) { 2575 if (info->feature_persistent) { 2576 need_schedule_work = true; 2577 mutex_lock(&info->mutex); 2578 purge_persistent_grants(info); 2579 mutex_unlock(&info->mutex); 2580 } 2581 } 2582 2583 if (need_schedule_work) 2584 schedule_delayed_work(&blkfront_work, HZ * 10); 2585 2586 mutex_unlock(&blkfront_mutex); 2587} 2588 2589static int __init xlblk_init(void) 2590{ 2591 int ret; 2592 int nr_cpus = num_online_cpus(); 2593 2594 if (!xen_domain()) 2595 return -ENODEV; 2596 2597 if (!xen_has_pv_disk_devices()) 2598 return -ENODEV; 2599 2600 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2601 pr_warn("xen_blk: can't get major %d with name %s\n", 2602 XENVBD_MAJOR, DEV_NAME); 2603 return -ENODEV; 2604 } 2605 2606 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST) 2607 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2608 2609 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { 2610 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 2611 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); 2612 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 2613 } 2614 2615 if (xen_blkif_max_queues > nr_cpus) { 2616 pr_info("Invalid max_queues (%d), will use default max: %d.\n", 2617 xen_blkif_max_queues, nr_cpus); 2618 xen_blkif_max_queues = nr_cpus; 2619 } 2620 2621 INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work); 2622 2623 ret = xenbus_register_frontend(&blkfront_driver); 2624 if (ret) { 2625 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2626 return ret; 2627 } 2628 2629 return 0; 2630} 2631module_init(xlblk_init); 2632 2633 2634static void __exit xlblk_exit(void) 2635{ 2636 cancel_delayed_work_sync(&blkfront_work); 2637 2638 xenbus_unregister_driver(&blkfront_driver); 2639 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2640 kfree(minors); 2641} 2642module_exit(xlblk_exit); 2643 2644MODULE_DESCRIPTION("Xen virtual block device frontend"); 2645MODULE_LICENSE("GPL"); 2646MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2647MODULE_ALIAS("xen:vbd"); 2648MODULE_ALIAS("xenblk"); 2649