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 80 enum blkif_state { 81 BLKIF_STATE_DISCONNECTED, 82 BLKIF_STATE_CONNECTED, 83 BLKIF_STATE_SUSPENDED, 84 BLKIF_STATE_ERROR, 85 }; 86 87 struct grant { 88 grant_ref_t gref; 89 struct page *page; 90 struct list_head node; 91 }; 92 93 enum blk_req_status { 94 REQ_PROCESSING, 95 REQ_WAITING, 96 REQ_DONE, 97 REQ_ERROR, 98 REQ_EOPNOTSUPP, 99 }; 100 101 struct 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 }; 117 118 struct blkif_req { 119 blk_status_t error; 120 }; 121 122 static inline struct blkif_req *blkif_req(struct request *rq) 123 { 124 return blk_mq_rq_to_pdu(rq); 125 } 126 127 static DEFINE_MUTEX(blkfront_mutex); 128 static const struct block_device_operations xlvbd_block_fops; 129 static struct delayed_work blkfront_work; 130 static 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 */ 137 138 static unsigned int xen_blkif_max_segments = 32; 139 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444); 140 MODULE_PARM_DESC(max_indirect_segments, 141 "Maximum amount of segments in indirect requests (default is 32)"); 142 143 static unsigned int xen_blkif_max_queues = 4; 144 module_param_named(max_queues, xen_blkif_max_queues, uint, 0444); 145 MODULE_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 */ 151 static unsigned int xen_blkif_max_ring_order; 152 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444); 153 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 154 155 static bool __read_mostly xen_blkif_trusted = true; 156 module_param_named(trusted, xen_blkif_trusted, bool, 0644); 157 MODULE_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 */ 177 struct 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 */ 198 struct 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 }; 235 236 static unsigned int nr_minors; 237 static unsigned long *minors; 238 static 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) 269 270 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo); 271 static void blkfront_gather_backend_features(struct blkfront_info *info); 272 static 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) 278 279 static inline struct blkfront_ring_info * 280 get_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 } 285 286 static 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 } 295 296 static 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 } 308 309 static 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; 336 337 out_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 } 349 350 static 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 } 364 365 static 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 } 373 374 static 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 } 398 399 static 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 } 425 426 static 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 } 443 static 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 } 479 480 static 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 } 489 490 static 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 } 495 496 static 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 } 511 512 static int blkif_ioctl(struct block_device *bdev, fmode_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 } 532 533 static 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 } 551 552 static 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 } 577 578 struct 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 }; 593 594 static 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 } 682 683 static 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 } 701 702 static 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 */ 868 static 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 } 879 880 static 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 } 889 890 static 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 } 899 900 static 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; 923 924 out_err: 925 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 926 return BLK_STS_IOERR; 927 928 out_busy: 929 blk_mq_stop_hw_queue(hctx); 930 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 931 return BLK_STS_DEV_RESOURCE; 932 } 933 934 static void blkif_complete_rq(struct request *rq) 935 { 936 blk_mq_end_request(rq, blkif_req(rq)->error); 937 } 938 939 static const struct blk_mq_ops blkfront_mq_ops = { 940 .queue_rq = blkif_queue_rq, 941 .complete = blkif_complete_rq, 942 }; 943 944 static void blkif_set_queue_limits(struct blkfront_info *info) 945 { 946 struct request_queue *rq = info->rq; 947 struct gendisk *gd = info->gd; 948 unsigned int segments = info->max_indirect_segments ? : 949 BLKIF_MAX_SEGMENTS_PER_REQUEST; 950 951 blk_queue_flag_set(QUEUE_FLAG_VIRT, rq); 952 953 if (info->feature_discard) { 954 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 955 rq->limits.discard_granularity = info->discard_granularity ?: 956 info->physical_sector_size; 957 rq->limits.discard_alignment = info->discard_alignment; 958 if (info->feature_secdiscard) 959 blk_queue_max_secure_erase_sectors(rq, 960 get_capacity(gd)); 961 } 962 963 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 964 blk_queue_logical_block_size(rq, info->sector_size); 965 blk_queue_physical_block_size(rq, info->physical_sector_size); 966 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512); 967 968 /* Each segment in a request is up to an aligned page in size. */ 969 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 970 blk_queue_max_segment_size(rq, PAGE_SIZE); 971 972 /* Ensure a merged request will fit in a single I/O ring slot. */ 973 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG); 974 975 /* Make sure buffer addresses are sector-aligned. */ 976 blk_queue_dma_alignment(rq, 511); 977 } 978 979 static const char *flush_info(struct blkfront_info *info) 980 { 981 if (info->feature_flush && info->feature_fua) 982 return "barrier: enabled;"; 983 else if (info->feature_flush) 984 return "flush diskcache: enabled;"; 985 else 986 return "barrier or flush: disabled;"; 987 } 988 989 static void xlvbd_flush(struct blkfront_info *info) 990 { 991 blk_queue_write_cache(info->rq, info->feature_flush ? true : false, 992 info->feature_fua ? true : false); 993 pr_info("blkfront: %s: %s %s %s %s %s %s %s\n", 994 info->gd->disk_name, flush_info(info), 995 "persistent grants:", info->feature_persistent ? 996 "enabled;" : "disabled;", "indirect descriptors:", 997 info->max_indirect_segments ? "enabled;" : "disabled;", 998 "bounce buffer:", info->bounce ? "enabled" : "disabled;"); 999 } 1000 1001 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 1002 { 1003 int major; 1004 major = BLKIF_MAJOR(vdevice); 1005 *minor = BLKIF_MINOR(vdevice); 1006 switch (major) { 1007 case XEN_IDE0_MAJOR: 1008 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 1009 *minor = ((*minor / 64) * PARTS_PER_DISK) + 1010 EMULATED_HD_DISK_MINOR_OFFSET; 1011 break; 1012 case XEN_IDE1_MAJOR: 1013 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 1014 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 1015 EMULATED_HD_DISK_MINOR_OFFSET; 1016 break; 1017 case XEN_SCSI_DISK0_MAJOR: 1018 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 1019 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 1020 break; 1021 case XEN_SCSI_DISK1_MAJOR: 1022 case XEN_SCSI_DISK2_MAJOR: 1023 case XEN_SCSI_DISK3_MAJOR: 1024 case XEN_SCSI_DISK4_MAJOR: 1025 case XEN_SCSI_DISK5_MAJOR: 1026 case XEN_SCSI_DISK6_MAJOR: 1027 case XEN_SCSI_DISK7_MAJOR: 1028 *offset = (*minor / PARTS_PER_DISK) + 1029 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 1030 EMULATED_SD_DISK_NAME_OFFSET; 1031 *minor = *minor + 1032 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 1033 EMULATED_SD_DISK_MINOR_OFFSET; 1034 break; 1035 case XEN_SCSI_DISK8_MAJOR: 1036 case XEN_SCSI_DISK9_MAJOR: 1037 case XEN_SCSI_DISK10_MAJOR: 1038 case XEN_SCSI_DISK11_MAJOR: 1039 case XEN_SCSI_DISK12_MAJOR: 1040 case XEN_SCSI_DISK13_MAJOR: 1041 case XEN_SCSI_DISK14_MAJOR: 1042 case XEN_SCSI_DISK15_MAJOR: 1043 *offset = (*minor / PARTS_PER_DISK) + 1044 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 1045 EMULATED_SD_DISK_NAME_OFFSET; 1046 *minor = *minor + 1047 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 1048 EMULATED_SD_DISK_MINOR_OFFSET; 1049 break; 1050 case XENVBD_MAJOR: 1051 *offset = *minor / PARTS_PER_DISK; 1052 break; 1053 default: 1054 printk(KERN_WARNING "blkfront: your disk configuration is " 1055 "incorrect, please use an xvd device instead\n"); 1056 return -ENODEV; 1057 } 1058 return 0; 1059 } 1060 1061 static char *encode_disk_name(char *ptr, unsigned int n) 1062 { 1063 if (n >= 26) 1064 ptr = encode_disk_name(ptr, n / 26 - 1); 1065 *ptr = 'a' + n % 26; 1066 return ptr + 1; 1067 } 1068 1069 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 1070 struct blkfront_info *info, u16 sector_size, 1071 unsigned int physical_sector_size) 1072 { 1073 struct gendisk *gd; 1074 int nr_minors = 1; 1075 int err; 1076 unsigned int offset; 1077 int minor; 1078 int nr_parts; 1079 char *ptr; 1080 1081 BUG_ON(info->gd != NULL); 1082 BUG_ON(info->rq != NULL); 1083 1084 if ((info->vdevice>>EXT_SHIFT) > 1) { 1085 /* this is above the extended range; something is wrong */ 1086 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 1087 return -ENODEV; 1088 } 1089 1090 if (!VDEV_IS_EXTENDED(info->vdevice)) { 1091 err = xen_translate_vdev(info->vdevice, &minor, &offset); 1092 if (err) 1093 return err; 1094 nr_parts = PARTS_PER_DISK; 1095 } else { 1096 minor = BLKIF_MINOR_EXT(info->vdevice); 1097 nr_parts = PARTS_PER_EXT_DISK; 1098 offset = minor / nr_parts; 1099 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 1100 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 1101 "emulated IDE disks,\n\t choose an xvd device name" 1102 "from xvde on\n", info->vdevice); 1103 } 1104 if (minor >> MINORBITS) { 1105 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 1106 info->vdevice, minor); 1107 return -ENODEV; 1108 } 1109 1110 if ((minor % nr_parts) == 0) 1111 nr_minors = nr_parts; 1112 1113 err = xlbd_reserve_minors(minor, nr_minors); 1114 if (err) 1115 return err; 1116 1117 memset(&info->tag_set, 0, sizeof(info->tag_set)); 1118 info->tag_set.ops = &blkfront_mq_ops; 1119 info->tag_set.nr_hw_queues = info->nr_rings; 1120 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) { 1121 /* 1122 * When indirect descriptior is not supported, the I/O request 1123 * will be split between multiple request in the ring. 1124 * To avoid problems when sending the request, divide by 1125 * 2 the depth of the queue. 1126 */ 1127 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2; 1128 } else 1129 info->tag_set.queue_depth = BLK_RING_SIZE(info); 1130 info->tag_set.numa_node = NUMA_NO_NODE; 1131 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; 1132 info->tag_set.cmd_size = sizeof(struct blkif_req); 1133 info->tag_set.driver_data = info; 1134 1135 err = blk_mq_alloc_tag_set(&info->tag_set); 1136 if (err) 1137 goto out_release_minors; 1138 1139 gd = blk_mq_alloc_disk(&info->tag_set, info); 1140 if (IS_ERR(gd)) { 1141 err = PTR_ERR(gd); 1142 goto out_free_tag_set; 1143 } 1144 1145 strcpy(gd->disk_name, DEV_NAME); 1146 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 1147 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 1148 if (nr_minors > 1) 1149 *ptr = 0; 1150 else 1151 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 1152 "%d", minor & (nr_parts - 1)); 1153 1154 gd->major = XENVBD_MAJOR; 1155 gd->first_minor = minor; 1156 gd->minors = nr_minors; 1157 gd->fops = &xlvbd_block_fops; 1158 gd->private_data = info; 1159 set_capacity(gd, capacity); 1160 1161 info->rq = gd->queue; 1162 info->gd = gd; 1163 info->sector_size = sector_size; 1164 info->physical_sector_size = physical_sector_size; 1165 blkif_set_queue_limits(info); 1166 1167 xlvbd_flush(info); 1168 1169 if (info->vdisk_info & VDISK_READONLY) 1170 set_disk_ro(gd, 1); 1171 if (info->vdisk_info & VDISK_REMOVABLE) 1172 gd->flags |= GENHD_FL_REMOVABLE; 1173 1174 return 0; 1175 1176 out_free_tag_set: 1177 blk_mq_free_tag_set(&info->tag_set); 1178 out_release_minors: 1179 xlbd_release_minors(minor, nr_minors); 1180 return err; 1181 } 1182 1183 /* Already hold rinfo->ring_lock. */ 1184 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo) 1185 { 1186 if (!RING_FULL(&rinfo->ring)) 1187 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true); 1188 } 1189 1190 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo) 1191 { 1192 unsigned long flags; 1193 1194 spin_lock_irqsave(&rinfo->ring_lock, flags); 1195 kick_pending_request_queues_locked(rinfo); 1196 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1197 } 1198 1199 static void blkif_restart_queue(struct work_struct *work) 1200 { 1201 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work); 1202 1203 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED) 1204 kick_pending_request_queues(rinfo); 1205 } 1206 1207 static void blkif_free_ring(struct blkfront_ring_info *rinfo) 1208 { 1209 struct grant *persistent_gnt, *n; 1210 struct blkfront_info *info = rinfo->dev_info; 1211 int i, j, segs; 1212 1213 /* 1214 * Remove indirect pages, this only happens when using indirect 1215 * descriptors but not persistent grants 1216 */ 1217 if (!list_empty(&rinfo->indirect_pages)) { 1218 struct page *indirect_page, *n; 1219 1220 BUG_ON(info->bounce); 1221 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 1222 list_del(&indirect_page->lru); 1223 __free_page(indirect_page); 1224 } 1225 } 1226 1227 /* Remove all persistent grants. */ 1228 if (!list_empty(&rinfo->grants)) { 1229 list_for_each_entry_safe(persistent_gnt, n, 1230 &rinfo->grants, node) { 1231 list_del(&persistent_gnt->node); 1232 if (persistent_gnt->gref != INVALID_GRANT_REF) { 1233 gnttab_end_foreign_access(persistent_gnt->gref, 1234 NULL); 1235 rinfo->persistent_gnts_c--; 1236 } 1237 if (info->bounce) 1238 __free_page(persistent_gnt->page); 1239 kfree(persistent_gnt); 1240 } 1241 } 1242 BUG_ON(rinfo->persistent_gnts_c != 0); 1243 1244 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1245 /* 1246 * Clear persistent grants present in requests already 1247 * on the shared ring 1248 */ 1249 if (!rinfo->shadow[i].request) 1250 goto free_shadow; 1251 1252 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 1253 rinfo->shadow[i].req.u.indirect.nr_segments : 1254 rinfo->shadow[i].req.u.rw.nr_segments; 1255 for (j = 0; j < segs; j++) { 1256 persistent_gnt = rinfo->shadow[i].grants_used[j]; 1257 gnttab_end_foreign_access(persistent_gnt->gref, NULL); 1258 if (info->bounce) 1259 __free_page(persistent_gnt->page); 1260 kfree(persistent_gnt); 1261 } 1262 1263 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT) 1264 /* 1265 * If this is not an indirect operation don't try to 1266 * free indirect segments 1267 */ 1268 goto free_shadow; 1269 1270 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 1271 persistent_gnt = rinfo->shadow[i].indirect_grants[j]; 1272 gnttab_end_foreign_access(persistent_gnt->gref, NULL); 1273 __free_page(persistent_gnt->page); 1274 kfree(persistent_gnt); 1275 } 1276 1277 free_shadow: 1278 kvfree(rinfo->shadow[i].grants_used); 1279 rinfo->shadow[i].grants_used = NULL; 1280 kvfree(rinfo->shadow[i].indirect_grants); 1281 rinfo->shadow[i].indirect_grants = NULL; 1282 kvfree(rinfo->shadow[i].sg); 1283 rinfo->shadow[i].sg = NULL; 1284 } 1285 1286 /* No more gnttab callback work. */ 1287 gnttab_cancel_free_callback(&rinfo->callback); 1288 1289 /* Flush gnttab callback work. Must be done with no locks held. */ 1290 flush_work(&rinfo->work); 1291 1292 /* Free resources associated with old device channel. */ 1293 xenbus_teardown_ring((void **)&rinfo->ring.sring, info->nr_ring_pages, 1294 rinfo->ring_ref); 1295 1296 if (rinfo->irq) 1297 unbind_from_irqhandler(rinfo->irq, rinfo); 1298 rinfo->evtchn = rinfo->irq = 0; 1299 } 1300 1301 static void blkif_free(struct blkfront_info *info, int suspend) 1302 { 1303 unsigned int i; 1304 struct blkfront_ring_info *rinfo; 1305 1306 /* Prevent new requests being issued until we fix things up. */ 1307 info->connected = suspend ? 1308 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 1309 /* No more blkif_request(). */ 1310 if (info->rq) 1311 blk_mq_stop_hw_queues(info->rq); 1312 1313 for_each_rinfo(info, rinfo, i) 1314 blkif_free_ring(rinfo); 1315 1316 kvfree(info->rinfo); 1317 info->rinfo = NULL; 1318 info->nr_rings = 0; 1319 } 1320 1321 struct copy_from_grant { 1322 const struct blk_shadow *s; 1323 unsigned int grant_idx; 1324 unsigned int bvec_offset; 1325 char *bvec_data; 1326 }; 1327 1328 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset, 1329 unsigned int len, void *data) 1330 { 1331 struct copy_from_grant *info = data; 1332 char *shared_data; 1333 /* Convenient aliases */ 1334 const struct blk_shadow *s = info->s; 1335 1336 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page); 1337 1338 memcpy(info->bvec_data + info->bvec_offset, 1339 shared_data + offset, len); 1340 1341 info->bvec_offset += len; 1342 info->grant_idx++; 1343 1344 kunmap_atomic(shared_data); 1345 } 1346 1347 static enum blk_req_status blkif_rsp_to_req_status(int rsp) 1348 { 1349 switch (rsp) 1350 { 1351 case BLKIF_RSP_OKAY: 1352 return REQ_DONE; 1353 case BLKIF_RSP_EOPNOTSUPP: 1354 return REQ_EOPNOTSUPP; 1355 case BLKIF_RSP_ERROR: 1356 default: 1357 return REQ_ERROR; 1358 } 1359 } 1360 1361 /* 1362 * Get the final status of the block request based on two ring response 1363 */ 1364 static int blkif_get_final_status(enum blk_req_status s1, 1365 enum blk_req_status s2) 1366 { 1367 BUG_ON(s1 < REQ_DONE); 1368 BUG_ON(s2 < REQ_DONE); 1369 1370 if (s1 == REQ_ERROR || s2 == REQ_ERROR) 1371 return BLKIF_RSP_ERROR; 1372 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP) 1373 return BLKIF_RSP_EOPNOTSUPP; 1374 return BLKIF_RSP_OKAY; 1375 } 1376 1377 /* 1378 * Return values: 1379 * 1 response processed. 1380 * 0 missing further responses. 1381 * -1 error while processing. 1382 */ 1383 static int blkif_completion(unsigned long *id, 1384 struct blkfront_ring_info *rinfo, 1385 struct blkif_response *bret) 1386 { 1387 int i = 0; 1388 struct scatterlist *sg; 1389 int num_sg, num_grant; 1390 struct blkfront_info *info = rinfo->dev_info; 1391 struct blk_shadow *s = &rinfo->shadow[*id]; 1392 struct copy_from_grant data = { 1393 .grant_idx = 0, 1394 }; 1395 1396 num_grant = s->req.operation == BLKIF_OP_INDIRECT ? 1397 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1398 1399 /* The I/O request may be split in two. */ 1400 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) { 1401 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id]; 1402 1403 /* Keep the status of the current response in shadow. */ 1404 s->status = blkif_rsp_to_req_status(bret->status); 1405 1406 /* Wait the second response if not yet here. */ 1407 if (s2->status < REQ_DONE) 1408 return 0; 1409 1410 bret->status = blkif_get_final_status(s->status, 1411 s2->status); 1412 1413 /* 1414 * All the grants is stored in the first shadow in order 1415 * to make the completion code simpler. 1416 */ 1417 num_grant += s2->req.u.rw.nr_segments; 1418 1419 /* 1420 * The two responses may not come in order. Only the 1421 * first request will store the scatter-gather list. 1422 */ 1423 if (s2->num_sg != 0) { 1424 /* Update "id" with the ID of the first response. */ 1425 *id = s->associated_id; 1426 s = s2; 1427 } 1428 1429 /* 1430 * We don't need anymore the second request, so recycling 1431 * it now. 1432 */ 1433 if (add_id_to_freelist(rinfo, s->associated_id)) 1434 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n", 1435 info->gd->disk_name, s->associated_id); 1436 } 1437 1438 data.s = s; 1439 num_sg = s->num_sg; 1440 1441 if (bret->operation == BLKIF_OP_READ && info->bounce) { 1442 for_each_sg(s->sg, sg, num_sg, i) { 1443 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1444 1445 data.bvec_offset = sg->offset; 1446 data.bvec_data = kmap_atomic(sg_page(sg)); 1447 1448 gnttab_foreach_grant_in_range(sg_page(sg), 1449 sg->offset, 1450 sg->length, 1451 blkif_copy_from_grant, 1452 &data); 1453 1454 kunmap_atomic(data.bvec_data); 1455 } 1456 } 1457 /* Add the persistent grant into the list of free grants */ 1458 for (i = 0; i < num_grant; i++) { 1459 if (!gnttab_try_end_foreign_access(s->grants_used[i]->gref)) { 1460 /* 1461 * If the grant is still mapped by the backend (the 1462 * backend has chosen to make this grant persistent) 1463 * we add it at the head of the list, so it will be 1464 * reused first. 1465 */ 1466 if (!info->feature_persistent) { 1467 pr_alert("backed has not unmapped grant: %u\n", 1468 s->grants_used[i]->gref); 1469 return -1; 1470 } 1471 list_add(&s->grants_used[i]->node, &rinfo->grants); 1472 rinfo->persistent_gnts_c++; 1473 } else { 1474 /* 1475 * If the grant is not mapped by the backend we add it 1476 * to the tail of the list, so it will not be picked 1477 * again unless we run out of persistent grants. 1478 */ 1479 s->grants_used[i]->gref = INVALID_GRANT_REF; 1480 list_add_tail(&s->grants_used[i]->node, &rinfo->grants); 1481 } 1482 } 1483 if (s->req.operation == BLKIF_OP_INDIRECT) { 1484 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) { 1485 if (!gnttab_try_end_foreign_access(s->indirect_grants[i]->gref)) { 1486 if (!info->feature_persistent) { 1487 pr_alert("backed has not unmapped grant: %u\n", 1488 s->indirect_grants[i]->gref); 1489 return -1; 1490 } 1491 list_add(&s->indirect_grants[i]->node, &rinfo->grants); 1492 rinfo->persistent_gnts_c++; 1493 } else { 1494 struct page *indirect_page; 1495 1496 /* 1497 * Add the used indirect page back to the list of 1498 * available pages for indirect grefs. 1499 */ 1500 if (!info->bounce) { 1501 indirect_page = s->indirect_grants[i]->page; 1502 list_add(&indirect_page->lru, &rinfo->indirect_pages); 1503 } 1504 s->indirect_grants[i]->gref = INVALID_GRANT_REF; 1505 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants); 1506 } 1507 } 1508 } 1509 1510 return 1; 1511 } 1512 1513 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1514 { 1515 struct request *req; 1516 struct blkif_response bret; 1517 RING_IDX i, rp; 1518 unsigned long flags; 1519 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id; 1520 struct blkfront_info *info = rinfo->dev_info; 1521 unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS; 1522 1523 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { 1524 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS); 1525 return IRQ_HANDLED; 1526 } 1527 1528 spin_lock_irqsave(&rinfo->ring_lock, flags); 1529 again: 1530 rp = READ_ONCE(rinfo->ring.sring->rsp_prod); 1531 virt_rmb(); /* Ensure we see queued responses up to 'rp'. */ 1532 if (RING_RESPONSE_PROD_OVERFLOW(&rinfo->ring, rp)) { 1533 pr_alert("%s: illegal number of responses %u\n", 1534 info->gd->disk_name, rp - rinfo->ring.rsp_cons); 1535 goto err; 1536 } 1537 1538 for (i = rinfo->ring.rsp_cons; i != rp; i++) { 1539 unsigned long id; 1540 unsigned int op; 1541 1542 eoiflag = 0; 1543 1544 RING_COPY_RESPONSE(&rinfo->ring, i, &bret); 1545 id = bret.id; 1546 1547 /* 1548 * The backend has messed up and given us an id that we would 1549 * never have given to it (we stamp it up to BLK_RING_SIZE - 1550 * look in get_id_from_freelist. 1551 */ 1552 if (id >= BLK_RING_SIZE(info)) { 1553 pr_alert("%s: response has incorrect id (%ld)\n", 1554 info->gd->disk_name, id); 1555 goto err; 1556 } 1557 if (rinfo->shadow[id].status != REQ_WAITING) { 1558 pr_alert("%s: response references no pending request\n", 1559 info->gd->disk_name); 1560 goto err; 1561 } 1562 1563 rinfo->shadow[id].status = REQ_PROCESSING; 1564 req = rinfo->shadow[id].request; 1565 1566 op = rinfo->shadow[id].req.operation; 1567 if (op == BLKIF_OP_INDIRECT) 1568 op = rinfo->shadow[id].req.u.indirect.indirect_op; 1569 if (bret.operation != op) { 1570 pr_alert("%s: response has wrong operation (%u instead of %u)\n", 1571 info->gd->disk_name, bret.operation, op); 1572 goto err; 1573 } 1574 1575 if (bret.operation != BLKIF_OP_DISCARD) { 1576 int ret; 1577 1578 /* 1579 * We may need to wait for an extra response if the 1580 * I/O request is split in 2 1581 */ 1582 ret = blkif_completion(&id, rinfo, &bret); 1583 if (!ret) 1584 continue; 1585 if (unlikely(ret < 0)) 1586 goto err; 1587 } 1588 1589 if (add_id_to_freelist(rinfo, id)) { 1590 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1591 info->gd->disk_name, op_name(bret.operation), id); 1592 continue; 1593 } 1594 1595 if (bret.status == BLKIF_RSP_OKAY) 1596 blkif_req(req)->error = BLK_STS_OK; 1597 else 1598 blkif_req(req)->error = BLK_STS_IOERR; 1599 1600 switch (bret.operation) { 1601 case BLKIF_OP_DISCARD: 1602 if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) { 1603 struct request_queue *rq = info->rq; 1604 1605 pr_warn_ratelimited("blkfront: %s: %s op failed\n", 1606 info->gd->disk_name, op_name(bret.operation)); 1607 blkif_req(req)->error = BLK_STS_NOTSUPP; 1608 info->feature_discard = 0; 1609 info->feature_secdiscard = 0; 1610 blk_queue_max_discard_sectors(rq, 0); 1611 blk_queue_max_secure_erase_sectors(rq, 0); 1612 } 1613 break; 1614 case BLKIF_OP_FLUSH_DISKCACHE: 1615 case BLKIF_OP_WRITE_BARRIER: 1616 if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) { 1617 pr_warn_ratelimited("blkfront: %s: %s op failed\n", 1618 info->gd->disk_name, op_name(bret.operation)); 1619 blkif_req(req)->error = BLK_STS_NOTSUPP; 1620 } 1621 if (unlikely(bret.status == BLKIF_RSP_ERROR && 1622 rinfo->shadow[id].req.u.rw.nr_segments == 0)) { 1623 pr_warn_ratelimited("blkfront: %s: empty %s op failed\n", 1624 info->gd->disk_name, op_name(bret.operation)); 1625 blkif_req(req)->error = BLK_STS_NOTSUPP; 1626 } 1627 if (unlikely(blkif_req(req)->error)) { 1628 if (blkif_req(req)->error == BLK_STS_NOTSUPP) 1629 blkif_req(req)->error = BLK_STS_OK; 1630 info->feature_fua = 0; 1631 info->feature_flush = 0; 1632 xlvbd_flush(info); 1633 } 1634 fallthrough; 1635 case BLKIF_OP_READ: 1636 case BLKIF_OP_WRITE: 1637 if (unlikely(bret.status != BLKIF_RSP_OKAY)) 1638 dev_dbg_ratelimited(&info->xbdev->dev, 1639 "Bad return from blkdev data request: %#x\n", 1640 bret.status); 1641 1642 break; 1643 default: 1644 BUG(); 1645 } 1646 1647 if (likely(!blk_should_fake_timeout(req->q))) 1648 blk_mq_complete_request(req); 1649 } 1650 1651 rinfo->ring.rsp_cons = i; 1652 1653 if (i != rinfo->ring.req_prod_pvt) { 1654 int more_to_do; 1655 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do); 1656 if (more_to_do) 1657 goto again; 1658 } else 1659 rinfo->ring.sring->rsp_event = i + 1; 1660 1661 kick_pending_request_queues_locked(rinfo); 1662 1663 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1664 1665 xen_irq_lateeoi(irq, eoiflag); 1666 1667 return IRQ_HANDLED; 1668 1669 err: 1670 info->connected = BLKIF_STATE_ERROR; 1671 1672 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1673 1674 /* No EOI in order to avoid further interrupts. */ 1675 1676 pr_alert("%s disabled for further use\n", info->gd->disk_name); 1677 return IRQ_HANDLED; 1678 } 1679 1680 1681 static int setup_blkring(struct xenbus_device *dev, 1682 struct blkfront_ring_info *rinfo) 1683 { 1684 struct blkif_sring *sring; 1685 int err; 1686 struct blkfront_info *info = rinfo->dev_info; 1687 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE; 1688 1689 err = xenbus_setup_ring(dev, GFP_NOIO, (void **)&sring, 1690 info->nr_ring_pages, rinfo->ring_ref); 1691 if (err) 1692 goto fail; 1693 1694 XEN_FRONT_RING_INIT(&rinfo->ring, sring, ring_size); 1695 1696 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn); 1697 if (err) 1698 goto fail; 1699 1700 err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt, 1701 0, "blkif", rinfo); 1702 if (err <= 0) { 1703 xenbus_dev_fatal(dev, err, 1704 "bind_evtchn_to_irqhandler failed"); 1705 goto fail; 1706 } 1707 rinfo->irq = err; 1708 1709 return 0; 1710 fail: 1711 blkif_free(info, 0); 1712 return err; 1713 } 1714 1715 /* 1716 * Write out per-ring/queue nodes including ring-ref and event-channel, and each 1717 * ring buffer may have multi pages depending on ->nr_ring_pages. 1718 */ 1719 static int write_per_ring_nodes(struct xenbus_transaction xbt, 1720 struct blkfront_ring_info *rinfo, const char *dir) 1721 { 1722 int err; 1723 unsigned int i; 1724 const char *message = NULL; 1725 struct blkfront_info *info = rinfo->dev_info; 1726 1727 if (info->nr_ring_pages == 1) { 1728 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]); 1729 if (err) { 1730 message = "writing ring-ref"; 1731 goto abort_transaction; 1732 } 1733 } else { 1734 for (i = 0; i < info->nr_ring_pages; i++) { 1735 char ring_ref_name[RINGREF_NAME_LEN]; 1736 1737 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 1738 err = xenbus_printf(xbt, dir, ring_ref_name, 1739 "%u", rinfo->ring_ref[i]); 1740 if (err) { 1741 message = "writing ring-ref"; 1742 goto abort_transaction; 1743 } 1744 } 1745 } 1746 1747 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn); 1748 if (err) { 1749 message = "writing event-channel"; 1750 goto abort_transaction; 1751 } 1752 1753 return 0; 1754 1755 abort_transaction: 1756 xenbus_transaction_end(xbt, 1); 1757 if (message) 1758 xenbus_dev_fatal(info->xbdev, err, "%s", message); 1759 1760 return err; 1761 } 1762 1763 /* Enable the persistent grants feature. */ 1764 static bool feature_persistent = true; 1765 module_param(feature_persistent, bool, 0644); 1766 MODULE_PARM_DESC(feature_persistent, 1767 "Enables the persistent grants feature"); 1768 1769 /* Common code used when first setting up, and when resuming. */ 1770 static int talk_to_blkback(struct xenbus_device *dev, 1771 struct blkfront_info *info) 1772 { 1773 const char *message = NULL; 1774 struct xenbus_transaction xbt; 1775 int err; 1776 unsigned int i, max_page_order; 1777 unsigned int ring_page_order; 1778 struct blkfront_ring_info *rinfo; 1779 1780 if (!info) 1781 return -ENODEV; 1782 1783 /* Check if backend is trusted. */ 1784 info->bounce = !xen_blkif_trusted || 1785 !xenbus_read_unsigned(dev->nodename, "trusted", 1); 1786 1787 max_page_order = xenbus_read_unsigned(info->xbdev->otherend, 1788 "max-ring-page-order", 0); 1789 ring_page_order = min(xen_blkif_max_ring_order, max_page_order); 1790 info->nr_ring_pages = 1 << ring_page_order; 1791 1792 err = negotiate_mq(info); 1793 if (err) 1794 goto destroy_blkring; 1795 1796 for_each_rinfo(info, rinfo, i) { 1797 /* Create shared ring, alloc event channel. */ 1798 err = setup_blkring(dev, rinfo); 1799 if (err) 1800 goto destroy_blkring; 1801 } 1802 1803 again: 1804 err = xenbus_transaction_start(&xbt); 1805 if (err) { 1806 xenbus_dev_fatal(dev, err, "starting transaction"); 1807 goto destroy_blkring; 1808 } 1809 1810 if (info->nr_ring_pages > 1) { 1811 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u", 1812 ring_page_order); 1813 if (err) { 1814 message = "writing ring-page-order"; 1815 goto abort_transaction; 1816 } 1817 } 1818 1819 /* We already got the number of queues/rings in _probe */ 1820 if (info->nr_rings == 1) { 1821 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename); 1822 if (err) 1823 goto destroy_blkring; 1824 } else { 1825 char *path; 1826 size_t pathsize; 1827 1828 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u", 1829 info->nr_rings); 1830 if (err) { 1831 message = "writing multi-queue-num-queues"; 1832 goto abort_transaction; 1833 } 1834 1835 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN; 1836 path = kmalloc(pathsize, GFP_KERNEL); 1837 if (!path) { 1838 err = -ENOMEM; 1839 message = "ENOMEM while writing ring references"; 1840 goto abort_transaction; 1841 } 1842 1843 for_each_rinfo(info, rinfo, i) { 1844 memset(path, 0, pathsize); 1845 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i); 1846 err = write_per_ring_nodes(xbt, rinfo, path); 1847 if (err) { 1848 kfree(path); 1849 goto destroy_blkring; 1850 } 1851 } 1852 kfree(path); 1853 } 1854 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1855 XEN_IO_PROTO_ABI_NATIVE); 1856 if (err) { 1857 message = "writing protocol"; 1858 goto abort_transaction; 1859 } 1860 info->feature_persistent_parm = feature_persistent; 1861 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1862 info->feature_persistent_parm); 1863 if (err) 1864 dev_warn(&dev->dev, 1865 "writing persistent grants feature to xenbus"); 1866 1867 err = xenbus_transaction_end(xbt, 0); 1868 if (err) { 1869 if (err == -EAGAIN) 1870 goto again; 1871 xenbus_dev_fatal(dev, err, "completing transaction"); 1872 goto destroy_blkring; 1873 } 1874 1875 for_each_rinfo(info, rinfo, i) { 1876 unsigned int j; 1877 1878 for (j = 0; j < BLK_RING_SIZE(info); j++) 1879 rinfo->shadow[j].req.u.rw.id = j + 1; 1880 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 1881 } 1882 xenbus_switch_state(dev, XenbusStateInitialised); 1883 1884 return 0; 1885 1886 abort_transaction: 1887 xenbus_transaction_end(xbt, 1); 1888 if (message) 1889 xenbus_dev_fatal(dev, err, "%s", message); 1890 destroy_blkring: 1891 blkif_free(info, 0); 1892 return err; 1893 } 1894 1895 static int negotiate_mq(struct blkfront_info *info) 1896 { 1897 unsigned int backend_max_queues; 1898 unsigned int i; 1899 struct blkfront_ring_info *rinfo; 1900 1901 BUG_ON(info->nr_rings); 1902 1903 /* Check if backend supports multiple queues. */ 1904 backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend, 1905 "multi-queue-max-queues", 1); 1906 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues); 1907 /* We need at least one ring. */ 1908 if (!info->nr_rings) 1909 info->nr_rings = 1; 1910 1911 info->rinfo_size = struct_size(info->rinfo, shadow, 1912 BLK_RING_SIZE(info)); 1913 info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL); 1914 if (!info->rinfo) { 1915 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure"); 1916 info->nr_rings = 0; 1917 return -ENOMEM; 1918 } 1919 1920 for_each_rinfo(info, rinfo, i) { 1921 INIT_LIST_HEAD(&rinfo->indirect_pages); 1922 INIT_LIST_HEAD(&rinfo->grants); 1923 rinfo->dev_info = info; 1924 INIT_WORK(&rinfo->work, blkif_restart_queue); 1925 spin_lock_init(&rinfo->ring_lock); 1926 } 1927 return 0; 1928 } 1929 1930 /* 1931 * Entry point to this code when a new device is created. Allocate the basic 1932 * structures and the ring buffer for communication with the backend, and 1933 * inform the backend of the appropriate details for those. Switch to 1934 * Initialised state. 1935 */ 1936 static int blkfront_probe(struct xenbus_device *dev, 1937 const struct xenbus_device_id *id) 1938 { 1939 int err, vdevice; 1940 struct blkfront_info *info; 1941 1942 /* FIXME: Use dynamic device id if this is not set. */ 1943 err = xenbus_scanf(XBT_NIL, dev->nodename, 1944 "virtual-device", "%i", &vdevice); 1945 if (err != 1) { 1946 /* go looking in the extended area instead */ 1947 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1948 "%i", &vdevice); 1949 if (err != 1) { 1950 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1951 return err; 1952 } 1953 } 1954 1955 if (xen_hvm_domain()) { 1956 char *type; 1957 int len; 1958 /* no unplug has been done: do not hook devices != xen vbds */ 1959 if (xen_has_pv_and_legacy_disk_devices()) { 1960 int major; 1961 1962 if (!VDEV_IS_EXTENDED(vdevice)) 1963 major = BLKIF_MAJOR(vdevice); 1964 else 1965 major = XENVBD_MAJOR; 1966 1967 if (major != XENVBD_MAJOR) { 1968 printk(KERN_INFO 1969 "%s: HVM does not support vbd %d as xen block device\n", 1970 __func__, vdevice); 1971 return -ENODEV; 1972 } 1973 } 1974 /* do not create a PV cdrom device if we are an HVM guest */ 1975 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1976 if (IS_ERR(type)) 1977 return -ENODEV; 1978 if (strncmp(type, "cdrom", 5) == 0) { 1979 kfree(type); 1980 return -ENODEV; 1981 } 1982 kfree(type); 1983 } 1984 info = kzalloc(sizeof(*info), GFP_KERNEL); 1985 if (!info) { 1986 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1987 return -ENOMEM; 1988 } 1989 1990 info->xbdev = dev; 1991 1992 mutex_init(&info->mutex); 1993 info->vdevice = vdevice; 1994 info->connected = BLKIF_STATE_DISCONNECTED; 1995 1996 /* Front end dir is a number, which is used as the id. */ 1997 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1998 dev_set_drvdata(&dev->dev, info); 1999 2000 mutex_lock(&blkfront_mutex); 2001 list_add(&info->info_list, &info_list); 2002 mutex_unlock(&blkfront_mutex); 2003 2004 return 0; 2005 } 2006 2007 static int blkif_recover(struct blkfront_info *info) 2008 { 2009 unsigned int r_index; 2010 struct request *req, *n; 2011 int rc; 2012 struct bio *bio; 2013 unsigned int segs; 2014 struct blkfront_ring_info *rinfo; 2015 2016 blkfront_gather_backend_features(info); 2017 /* Reset limits changed by blk_mq_update_nr_hw_queues(). */ 2018 blkif_set_queue_limits(info); 2019 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 2020 blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG); 2021 2022 for_each_rinfo(info, rinfo, r_index) { 2023 rc = blkfront_setup_indirect(rinfo); 2024 if (rc) 2025 return rc; 2026 } 2027 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2028 2029 /* Now safe for us to use the shared ring */ 2030 info->connected = BLKIF_STATE_CONNECTED; 2031 2032 for_each_rinfo(info, rinfo, r_index) { 2033 /* Kick any other new requests queued since we resumed */ 2034 kick_pending_request_queues(rinfo); 2035 } 2036 2037 list_for_each_entry_safe(req, n, &info->requests, queuelist) { 2038 /* Requeue pending requests (flush or discard) */ 2039 list_del_init(&req->queuelist); 2040 BUG_ON(req->nr_phys_segments > segs); 2041 blk_mq_requeue_request(req, false); 2042 } 2043 blk_mq_start_stopped_hw_queues(info->rq, true); 2044 blk_mq_kick_requeue_list(info->rq); 2045 2046 while ((bio = bio_list_pop(&info->bio_list)) != NULL) { 2047 /* Traverse the list of pending bios and re-queue them */ 2048 submit_bio(bio); 2049 } 2050 2051 return 0; 2052 } 2053 2054 /* 2055 * We are reconnecting to the backend, due to a suspend/resume, or a backend 2056 * driver restart. We tear down our blkif structure and recreate it, but 2057 * leave the device-layer structures intact so that this is transparent to the 2058 * rest of the kernel. 2059 */ 2060 static int blkfront_resume(struct xenbus_device *dev) 2061 { 2062 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2063 int err = 0; 2064 unsigned int i, j; 2065 struct blkfront_ring_info *rinfo; 2066 2067 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 2068 2069 bio_list_init(&info->bio_list); 2070 INIT_LIST_HEAD(&info->requests); 2071 for_each_rinfo(info, rinfo, i) { 2072 struct bio_list merge_bio; 2073 struct blk_shadow *shadow = rinfo->shadow; 2074 2075 for (j = 0; j < BLK_RING_SIZE(info); j++) { 2076 /* Not in use? */ 2077 if (!shadow[j].request) 2078 continue; 2079 2080 /* 2081 * Get the bios in the request so we can re-queue them. 2082 */ 2083 if (req_op(shadow[j].request) == REQ_OP_FLUSH || 2084 req_op(shadow[j].request) == REQ_OP_DISCARD || 2085 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE || 2086 shadow[j].request->cmd_flags & REQ_FUA) { 2087 /* 2088 * Flush operations don't contain bios, so 2089 * we need to requeue the whole request 2090 * 2091 * XXX: but this doesn't make any sense for a 2092 * write with the FUA flag set.. 2093 */ 2094 list_add(&shadow[j].request->queuelist, &info->requests); 2095 continue; 2096 } 2097 merge_bio.head = shadow[j].request->bio; 2098 merge_bio.tail = shadow[j].request->biotail; 2099 bio_list_merge(&info->bio_list, &merge_bio); 2100 shadow[j].request->bio = NULL; 2101 blk_mq_end_request(shadow[j].request, BLK_STS_OK); 2102 } 2103 } 2104 2105 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 2106 2107 err = talk_to_blkback(dev, info); 2108 if (!err) 2109 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings); 2110 2111 /* 2112 * We have to wait for the backend to switch to 2113 * connected state, since we want to read which 2114 * features it supports. 2115 */ 2116 2117 return err; 2118 } 2119 2120 static void blkfront_closing(struct blkfront_info *info) 2121 { 2122 struct xenbus_device *xbdev = info->xbdev; 2123 struct blkfront_ring_info *rinfo; 2124 unsigned int i; 2125 2126 if (xbdev->state == XenbusStateClosing) 2127 return; 2128 2129 /* No more blkif_request(). */ 2130 if (info->rq && info->gd) { 2131 blk_mq_stop_hw_queues(info->rq); 2132 blk_mark_disk_dead(info->gd); 2133 } 2134 2135 for_each_rinfo(info, rinfo, i) { 2136 /* No more gnttab callback work. */ 2137 gnttab_cancel_free_callback(&rinfo->callback); 2138 2139 /* Flush gnttab callback work. Must be done with no locks held. */ 2140 flush_work(&rinfo->work); 2141 } 2142 2143 xenbus_frontend_closed(xbdev); 2144 } 2145 2146 static void blkfront_setup_discard(struct blkfront_info *info) 2147 { 2148 info->feature_discard = 1; 2149 info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend, 2150 "discard-granularity", 2151 0); 2152 info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend, 2153 "discard-alignment", 0); 2154 info->feature_secdiscard = 2155 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure", 2156 0); 2157 } 2158 2159 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo) 2160 { 2161 unsigned int psegs, grants, memflags; 2162 int err, i; 2163 struct blkfront_info *info = rinfo->dev_info; 2164 2165 memflags = memalloc_noio_save(); 2166 2167 if (info->max_indirect_segments == 0) { 2168 if (!HAS_EXTRA_REQ) 2169 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2170 else { 2171 /* 2172 * When an extra req is required, the maximum 2173 * grants supported is related to the size of the 2174 * Linux block segment. 2175 */ 2176 grants = GRANTS_PER_PSEG; 2177 } 2178 } 2179 else 2180 grants = info->max_indirect_segments; 2181 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG); 2182 2183 err = fill_grant_buffer(rinfo, 2184 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info)); 2185 if (err) 2186 goto out_of_memory; 2187 2188 if (!info->bounce && info->max_indirect_segments) { 2189 /* 2190 * We are using indirect descriptors but don't have a bounce 2191 * buffer, we need to allocate a set of pages that can be 2192 * used for mapping indirect grefs 2193 */ 2194 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info); 2195 2196 BUG_ON(!list_empty(&rinfo->indirect_pages)); 2197 for (i = 0; i < num; i++) { 2198 struct page *indirect_page = alloc_page(GFP_KERNEL | 2199 __GFP_ZERO); 2200 if (!indirect_page) 2201 goto out_of_memory; 2202 list_add(&indirect_page->lru, &rinfo->indirect_pages); 2203 } 2204 } 2205 2206 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2207 rinfo->shadow[i].grants_used = 2208 kvcalloc(grants, 2209 sizeof(rinfo->shadow[i].grants_used[0]), 2210 GFP_KERNEL); 2211 rinfo->shadow[i].sg = kvcalloc(psegs, 2212 sizeof(rinfo->shadow[i].sg[0]), 2213 GFP_KERNEL); 2214 if (info->max_indirect_segments) 2215 rinfo->shadow[i].indirect_grants = 2216 kvcalloc(INDIRECT_GREFS(grants), 2217 sizeof(rinfo->shadow[i].indirect_grants[0]), 2218 GFP_KERNEL); 2219 if ((rinfo->shadow[i].grants_used == NULL) || 2220 (rinfo->shadow[i].sg == NULL) || 2221 (info->max_indirect_segments && 2222 (rinfo->shadow[i].indirect_grants == NULL))) 2223 goto out_of_memory; 2224 sg_init_table(rinfo->shadow[i].sg, psegs); 2225 } 2226 2227 memalloc_noio_restore(memflags); 2228 2229 return 0; 2230 2231 out_of_memory: 2232 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2233 kvfree(rinfo->shadow[i].grants_used); 2234 rinfo->shadow[i].grants_used = NULL; 2235 kvfree(rinfo->shadow[i].sg); 2236 rinfo->shadow[i].sg = NULL; 2237 kvfree(rinfo->shadow[i].indirect_grants); 2238 rinfo->shadow[i].indirect_grants = NULL; 2239 } 2240 if (!list_empty(&rinfo->indirect_pages)) { 2241 struct page *indirect_page, *n; 2242 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 2243 list_del(&indirect_page->lru); 2244 __free_page(indirect_page); 2245 } 2246 } 2247 2248 memalloc_noio_restore(memflags); 2249 2250 return -ENOMEM; 2251 } 2252 2253 /* 2254 * Gather all backend feature-* 2255 */ 2256 static void blkfront_gather_backend_features(struct blkfront_info *info) 2257 { 2258 unsigned int indirect_segments; 2259 2260 info->feature_flush = 0; 2261 info->feature_fua = 0; 2262 2263 /* 2264 * If there's no "feature-barrier" defined, then it means 2265 * we're dealing with a very old backend which writes 2266 * synchronously; nothing to do. 2267 * 2268 * If there are barriers, then we use flush. 2269 */ 2270 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) { 2271 info->feature_flush = 1; 2272 info->feature_fua = 1; 2273 } 2274 2275 /* 2276 * And if there is "feature-flush-cache" use that above 2277 * barriers. 2278 */ 2279 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache", 2280 0)) { 2281 info->feature_flush = 1; 2282 info->feature_fua = 0; 2283 } 2284 2285 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) 2286 blkfront_setup_discard(info); 2287 2288 if (info->feature_persistent_parm) 2289 info->feature_persistent = 2290 !!xenbus_read_unsigned(info->xbdev->otherend, 2291 "feature-persistent", 0); 2292 if (info->feature_persistent) 2293 info->bounce = true; 2294 2295 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend, 2296 "feature-max-indirect-segments", 0); 2297 if (indirect_segments > xen_blkif_max_segments) 2298 indirect_segments = xen_blkif_max_segments; 2299 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST) 2300 indirect_segments = 0; 2301 info->max_indirect_segments = indirect_segments; 2302 2303 if (info->feature_persistent) { 2304 mutex_lock(&blkfront_mutex); 2305 schedule_delayed_work(&blkfront_work, HZ * 10); 2306 mutex_unlock(&blkfront_mutex); 2307 } 2308 } 2309 2310 /* 2311 * Invoked when the backend is finally 'ready' (and has told produced 2312 * the details about the physical device - #sectors, size, etc). 2313 */ 2314 static void blkfront_connect(struct blkfront_info *info) 2315 { 2316 unsigned long long sectors; 2317 unsigned long sector_size; 2318 unsigned int physical_sector_size; 2319 int err, i; 2320 struct blkfront_ring_info *rinfo; 2321 2322 switch (info->connected) { 2323 case BLKIF_STATE_CONNECTED: 2324 /* 2325 * Potentially, the back-end may be signalling 2326 * a capacity change; update the capacity. 2327 */ 2328 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2329 "sectors", "%Lu", §ors); 2330 if (XENBUS_EXIST_ERR(err)) 2331 return; 2332 printk(KERN_INFO "Setting capacity to %Lu\n", 2333 sectors); 2334 set_capacity_and_notify(info->gd, sectors); 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", &info->vdisk_info, 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 * physical-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_each_rinfo(info, rinfo, i) { 2376 err = blkfront_setup_indirect(rinfo); 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, 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_each_rinfo(info, rinfo, i) 2398 kick_pending_request_queues(rinfo); 2399 2400 err = device_add_disk(&info->xbdev->dev, info->gd, NULL); 2401 if (err) { 2402 put_disk(info->gd); 2403 blk_mq_free_tag_set(&info->tag_set); 2404 info->rq = NULL; 2405 goto fail; 2406 } 2407 2408 info->is_ready = 1; 2409 return; 2410 2411 fail: 2412 blkif_free(info, 0); 2413 return; 2414 } 2415 2416 /* 2417 * Callback received when the backend's state changes. 2418 */ 2419 static void blkback_changed(struct xenbus_device *dev, 2420 enum xenbus_state backend_state) 2421 { 2422 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2423 2424 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 2425 2426 switch (backend_state) { 2427 case XenbusStateInitWait: 2428 if (dev->state != XenbusStateInitialising) 2429 break; 2430 if (talk_to_blkback(dev, info)) 2431 break; 2432 break; 2433 case XenbusStateInitialising: 2434 case XenbusStateInitialised: 2435 case XenbusStateReconfiguring: 2436 case XenbusStateReconfigured: 2437 case XenbusStateUnknown: 2438 break; 2439 2440 case XenbusStateConnected: 2441 /* 2442 * talk_to_blkback sets state to XenbusStateInitialised 2443 * and blkfront_connect sets it to XenbusStateConnected 2444 * (if connection went OK). 2445 * 2446 * If the backend (or toolstack) decides to poke at backend 2447 * state (and re-trigger the watch by setting the state repeatedly 2448 * to XenbusStateConnected (4)) we need to deal with this. 2449 * This is allowed as this is used to communicate to the guest 2450 * that the size of disk has changed! 2451 */ 2452 if ((dev->state != XenbusStateInitialised) && 2453 (dev->state != XenbusStateConnected)) { 2454 if (talk_to_blkback(dev, info)) 2455 break; 2456 } 2457 2458 blkfront_connect(info); 2459 break; 2460 2461 case XenbusStateClosed: 2462 if (dev->state == XenbusStateClosed) 2463 break; 2464 fallthrough; 2465 case XenbusStateClosing: 2466 blkfront_closing(info); 2467 break; 2468 } 2469 } 2470 2471 static void blkfront_remove(struct xenbus_device *xbdev) 2472 { 2473 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 2474 2475 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 2476 2477 if (info->gd) 2478 del_gendisk(info->gd); 2479 2480 mutex_lock(&blkfront_mutex); 2481 list_del(&info->info_list); 2482 mutex_unlock(&blkfront_mutex); 2483 2484 blkif_free(info, 0); 2485 if (info->gd) { 2486 xlbd_release_minors(info->gd->first_minor, info->gd->minors); 2487 put_disk(info->gd); 2488 blk_mq_free_tag_set(&info->tag_set); 2489 } 2490 2491 kfree(info); 2492 } 2493 2494 static int blkfront_is_ready(struct xenbus_device *dev) 2495 { 2496 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2497 2498 return info->is_ready && info->xbdev; 2499 } 2500 2501 static const struct block_device_operations xlvbd_block_fops = 2502 { 2503 .owner = THIS_MODULE, 2504 .getgeo = blkif_getgeo, 2505 .ioctl = blkif_ioctl, 2506 .compat_ioctl = blkdev_compat_ptr_ioctl, 2507 }; 2508 2509 2510 static const struct xenbus_device_id blkfront_ids[] = { 2511 { "vbd" }, 2512 { "" } 2513 }; 2514 2515 static struct xenbus_driver blkfront_driver = { 2516 .ids = blkfront_ids, 2517 .probe = blkfront_probe, 2518 .remove = blkfront_remove, 2519 .resume = blkfront_resume, 2520 .otherend_changed = blkback_changed, 2521 .is_ready = blkfront_is_ready, 2522 }; 2523 2524 static void purge_persistent_grants(struct blkfront_info *info) 2525 { 2526 unsigned int i; 2527 unsigned long flags; 2528 struct blkfront_ring_info *rinfo; 2529 2530 for_each_rinfo(info, rinfo, i) { 2531 struct grant *gnt_list_entry, *tmp; 2532 LIST_HEAD(grants); 2533 2534 spin_lock_irqsave(&rinfo->ring_lock, flags); 2535 2536 if (rinfo->persistent_gnts_c == 0) { 2537 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 2538 continue; 2539 } 2540 2541 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants, 2542 node) { 2543 if (gnt_list_entry->gref == INVALID_GRANT_REF || 2544 !gnttab_try_end_foreign_access(gnt_list_entry->gref)) 2545 continue; 2546 2547 list_del(&gnt_list_entry->node); 2548 rinfo->persistent_gnts_c--; 2549 gnt_list_entry->gref = INVALID_GRANT_REF; 2550 list_add_tail(&gnt_list_entry->node, &grants); 2551 } 2552 2553 list_splice_tail(&grants, &rinfo->grants); 2554 2555 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 2556 } 2557 } 2558 2559 static void blkfront_delay_work(struct work_struct *work) 2560 { 2561 struct blkfront_info *info; 2562 bool need_schedule_work = false; 2563 2564 /* 2565 * Note that when using bounce buffers but not persistent grants 2566 * there's no need to run blkfront_delay_work because grants are 2567 * revoked in blkif_completion or else an error is reported and the 2568 * connection is closed. 2569 */ 2570 2571 mutex_lock(&blkfront_mutex); 2572 2573 list_for_each_entry(info, &info_list, info_list) { 2574 if (info->feature_persistent) { 2575 need_schedule_work = true; 2576 mutex_lock(&info->mutex); 2577 purge_persistent_grants(info); 2578 mutex_unlock(&info->mutex); 2579 } 2580 } 2581 2582 if (need_schedule_work) 2583 schedule_delayed_work(&blkfront_work, HZ * 10); 2584 2585 mutex_unlock(&blkfront_mutex); 2586 } 2587 2588 static int __init xlblk_init(void) 2589 { 2590 int ret; 2591 int nr_cpus = num_online_cpus(); 2592 2593 if (!xen_domain()) 2594 return -ENODEV; 2595 2596 if (!xen_has_pv_disk_devices()) 2597 return -ENODEV; 2598 2599 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2600 pr_warn("xen_blk: can't get major %d with name %s\n", 2601 XENVBD_MAJOR, DEV_NAME); 2602 return -ENODEV; 2603 } 2604 2605 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST) 2606 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2607 2608 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { 2609 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 2610 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); 2611 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 2612 } 2613 2614 if (xen_blkif_max_queues > nr_cpus) { 2615 pr_info("Invalid max_queues (%d), will use default max: %d.\n", 2616 xen_blkif_max_queues, nr_cpus); 2617 xen_blkif_max_queues = nr_cpus; 2618 } 2619 2620 INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work); 2621 2622 ret = xenbus_register_frontend(&blkfront_driver); 2623 if (ret) { 2624 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2625 return ret; 2626 } 2627 2628 return 0; 2629 } 2630 module_init(xlblk_init); 2631 2632 2633 static void __exit xlblk_exit(void) 2634 { 2635 cancel_delayed_work_sync(&blkfront_work); 2636 2637 xenbus_unregister_driver(&blkfront_driver); 2638 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2639 kfree(minors); 2640 } 2641 module_exit(xlblk_exit); 2642 2643 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2644 MODULE_LICENSE("GPL"); 2645 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2646 MODULE_ALIAS("xen:vbd"); 2647 MODULE_ALIAS("xenblk"); 2648