1 /* 2 * blkfront.c 3 * 4 * XenLinux virtual block device driver. 5 * 6 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand 7 * Modifications by Mark A. Williamson are (c) Intel Research Cambridge 8 * Copyright (c) 2004, Christian Limpach 9 * Copyright (c) 2004, Andrew Warfield 10 * Copyright (c) 2005, Christopher Clark 11 * Copyright (c) 2005, XenSource Ltd 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License version 2 15 * as published by the Free Software Foundation; or, when distributed 16 * separately from the Linux kernel or incorporated into other 17 * software packages, subject to the following license: 18 * 19 * Permission is hereby granted, free of charge, to any person obtaining a copy 20 * of this source file (the "Software"), to deal in the Software without 21 * restriction, including without limitation the rights to use, copy, modify, 22 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 23 * and to permit persons to whom the Software is furnished to do so, subject to 24 * the following conditions: 25 * 26 * The above copyright notice and this permission notice shall be included in 27 * all copies or substantial portions of the Software. 28 * 29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 30 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 32 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 33 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 34 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 35 * IN THE SOFTWARE. 36 */ 37 38 #include <linux/interrupt.h> 39 #include <linux/blkdev.h> 40 #include <linux/blk-mq.h> 41 #include <linux/hdreg.h> 42 #include <linux/cdrom.h> 43 #include <linux/module.h> 44 #include <linux/slab.h> 45 #include <linux/mutex.h> 46 #include <linux/scatterlist.h> 47 #include <linux/bitmap.h> 48 #include <linux/list.h> 49 #include <linux/workqueue.h> 50 #include <linux/sched/mm.h> 51 52 #include <xen/xen.h> 53 #include <xen/xenbus.h> 54 #include <xen/grant_table.h> 55 #include <xen/events.h> 56 #include <xen/page.h> 57 #include <xen/platform_pci.h> 58 59 #include <xen/interface/grant_table.h> 60 #include <xen/interface/io/blkif.h> 61 #include <xen/interface/io/protocols.h> 62 63 #include <asm/xen/hypervisor.h> 64 65 /* 66 * The minimal size of segment supported by the block framework is PAGE_SIZE. 67 * When Linux is using a different page size than Xen, it may not be possible 68 * to put all the data in a single segment. 69 * This can happen when the backend doesn't support indirect descriptor and 70 * therefore the maximum amount of data that a request can carry is 71 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB 72 * 73 * Note that we only support one extra request. So the Linux page size 74 * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) = 75 * 88KB. 76 */ 77 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE) 78 79 enum blkif_state { 80 BLKIF_STATE_DISCONNECTED, 81 BLKIF_STATE_CONNECTED, 82 BLKIF_STATE_SUSPENDED, 83 }; 84 85 struct grant { 86 grant_ref_t gref; 87 struct page *page; 88 struct list_head node; 89 }; 90 91 enum blk_req_status { 92 REQ_WAITING, 93 REQ_DONE, 94 REQ_ERROR, 95 REQ_EOPNOTSUPP, 96 }; 97 98 struct blk_shadow { 99 struct blkif_request req; 100 struct request *request; 101 struct grant **grants_used; 102 struct grant **indirect_grants; 103 struct scatterlist *sg; 104 unsigned int num_sg; 105 enum blk_req_status status; 106 107 #define NO_ASSOCIATED_ID ~0UL 108 /* 109 * Id of the sibling if we ever need 2 requests when handling a 110 * block I/O request 111 */ 112 unsigned long associated_id; 113 }; 114 115 struct blkif_req { 116 blk_status_t error; 117 }; 118 119 static inline struct blkif_req *blkif_req(struct request *rq) 120 { 121 return blk_mq_rq_to_pdu(rq); 122 } 123 124 static DEFINE_MUTEX(blkfront_mutex); 125 static const struct block_device_operations xlvbd_block_fops; 126 static struct delayed_work blkfront_work; 127 static LIST_HEAD(info_list); 128 129 /* 130 * Maximum number of segments in indirect requests, the actual value used by 131 * the frontend driver is the minimum of this value and the value provided 132 * by the backend driver. 133 */ 134 135 static unsigned int xen_blkif_max_segments = 32; 136 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444); 137 MODULE_PARM_DESC(max_indirect_segments, 138 "Maximum amount of segments in indirect requests (default is 32)"); 139 140 static unsigned int xen_blkif_max_queues = 4; 141 module_param_named(max_queues, xen_blkif_max_queues, uint, 0444); 142 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk"); 143 144 /* 145 * Maximum order of pages to be used for the shared ring between front and 146 * backend, 4KB page granularity is used. 147 */ 148 static unsigned int xen_blkif_max_ring_order; 149 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444); 150 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 151 152 #define BLK_RING_SIZE(info) \ 153 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages) 154 155 /* 156 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 157 * characters are enough. Define to 20 to keep consistent with backend. 158 */ 159 #define RINGREF_NAME_LEN (20) 160 /* 161 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters. 162 */ 163 #define QUEUE_NAME_LEN (17) 164 165 /* 166 * Per-ring info. 167 * Every blkfront device can associate with one or more blkfront_ring_info, 168 * depending on how many hardware queues/rings to be used. 169 */ 170 struct blkfront_ring_info { 171 /* Lock to protect data in every ring buffer. */ 172 spinlock_t ring_lock; 173 struct blkif_front_ring ring; 174 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS]; 175 unsigned int evtchn, irq; 176 struct work_struct work; 177 struct gnttab_free_callback callback; 178 struct list_head indirect_pages; 179 struct list_head grants; 180 unsigned int persistent_gnts_c; 181 unsigned long shadow_free; 182 struct blkfront_info *dev_info; 183 struct blk_shadow shadow[]; 184 }; 185 186 /* 187 * We have one of these per vbd, whether ide, scsi or 'other'. They 188 * hang in private_data off the gendisk structure. We may end up 189 * putting all kinds of interesting stuff here :-) 190 */ 191 struct blkfront_info 192 { 193 struct mutex mutex; 194 struct xenbus_device *xbdev; 195 struct gendisk *gd; 196 u16 sector_size; 197 unsigned int physical_sector_size; 198 int vdevice; 199 blkif_vdev_t handle; 200 enum blkif_state connected; 201 /* Number of pages per ring buffer. */ 202 unsigned int nr_ring_pages; 203 struct request_queue *rq; 204 unsigned int feature_flush:1; 205 unsigned int feature_fua:1; 206 unsigned int feature_discard:1; 207 unsigned int feature_secdiscard:1; 208 unsigned int feature_persistent:1; 209 unsigned int discard_granularity; 210 unsigned int discard_alignment; 211 /* Number of 4KB segments handled */ 212 unsigned int max_indirect_segments; 213 int is_ready; 214 struct blk_mq_tag_set tag_set; 215 struct blkfront_ring_info *rinfo; 216 unsigned int nr_rings; 217 unsigned int rinfo_size; 218 /* Save uncomplete reqs and bios for migration. */ 219 struct list_head requests; 220 struct bio_list bio_list; 221 struct list_head info_list; 222 }; 223 224 static unsigned int nr_minors; 225 static unsigned long *minors; 226 static DEFINE_SPINLOCK(minor_lock); 227 228 #define GRANT_INVALID_REF 0 229 230 #define PARTS_PER_DISK 16 231 #define PARTS_PER_EXT_DISK 256 232 233 #define BLKIF_MAJOR(dev) ((dev)>>8) 234 #define BLKIF_MINOR(dev) ((dev) & 0xff) 235 236 #define EXT_SHIFT 28 237 #define EXTENDED (1<<EXT_SHIFT) 238 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 239 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 240 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 241 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 242 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 243 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 244 245 #define DEV_NAME "xvd" /* name in /dev */ 246 247 /* 248 * Grants are always the same size as a Xen page (i.e 4KB). 249 * A physical segment is always the same size as a Linux page. 250 * Number of grants per physical segment 251 */ 252 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE) 253 254 #define GRANTS_PER_INDIRECT_FRAME \ 255 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment)) 256 257 #define INDIRECT_GREFS(_grants) \ 258 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME) 259 260 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo); 261 static void blkfront_gather_backend_features(struct blkfront_info *info); 262 static int negotiate_mq(struct blkfront_info *info); 263 264 #define for_each_rinfo(info, ptr, idx) \ 265 for ((ptr) = (info)->rinfo, (idx) = 0; \ 266 (idx) < (info)->nr_rings; \ 267 (idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size) 268 269 static inline struct blkfront_ring_info * 270 get_rinfo(const struct blkfront_info *info, unsigned int i) 271 { 272 BUG_ON(i >= info->nr_rings); 273 return (void *)info->rinfo + i * info->rinfo_size; 274 } 275 276 static int get_id_from_freelist(struct blkfront_ring_info *rinfo) 277 { 278 unsigned long free = rinfo->shadow_free; 279 280 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info)); 281 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id; 282 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 283 return free; 284 } 285 286 static int add_id_to_freelist(struct blkfront_ring_info *rinfo, 287 unsigned long id) 288 { 289 if (rinfo->shadow[id].req.u.rw.id != id) 290 return -EINVAL; 291 if (rinfo->shadow[id].request == NULL) 292 return -EINVAL; 293 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free; 294 rinfo->shadow[id].request = NULL; 295 rinfo->shadow_free = id; 296 return 0; 297 } 298 299 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 300 { 301 struct blkfront_info *info = rinfo->dev_info; 302 struct page *granted_page; 303 struct grant *gnt_list_entry, *n; 304 int i = 0; 305 306 while (i < num) { 307 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 308 if (!gnt_list_entry) 309 goto out_of_memory; 310 311 if (info->feature_persistent) { 312 granted_page = alloc_page(GFP_NOIO); 313 if (!granted_page) { 314 kfree(gnt_list_entry); 315 goto out_of_memory; 316 } 317 gnt_list_entry->page = granted_page; 318 } 319 320 gnt_list_entry->gref = GRANT_INVALID_REF; 321 list_add(&gnt_list_entry->node, &rinfo->grants); 322 i++; 323 } 324 325 return 0; 326 327 out_of_memory: 328 list_for_each_entry_safe(gnt_list_entry, n, 329 &rinfo->grants, node) { 330 list_del(&gnt_list_entry->node); 331 if (info->feature_persistent) 332 __free_page(gnt_list_entry->page); 333 kfree(gnt_list_entry); 334 i--; 335 } 336 BUG_ON(i != 0); 337 return -ENOMEM; 338 } 339 340 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo) 341 { 342 struct grant *gnt_list_entry; 343 344 BUG_ON(list_empty(&rinfo->grants)); 345 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant, 346 node); 347 list_del(&gnt_list_entry->node); 348 349 if (gnt_list_entry->gref != GRANT_INVALID_REF) 350 rinfo->persistent_gnts_c--; 351 352 return gnt_list_entry; 353 } 354 355 static inline void grant_foreign_access(const struct grant *gnt_list_entry, 356 const struct blkfront_info *info) 357 { 358 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref, 359 info->xbdev->otherend_id, 360 gnt_list_entry->page, 361 0); 362 } 363 364 static struct grant *get_grant(grant_ref_t *gref_head, 365 unsigned long gfn, 366 struct blkfront_ring_info *rinfo) 367 { 368 struct grant *gnt_list_entry = get_free_grant(rinfo); 369 struct blkfront_info *info = rinfo->dev_info; 370 371 if (gnt_list_entry->gref != GRANT_INVALID_REF) 372 return gnt_list_entry; 373 374 /* Assign a gref to this page */ 375 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 376 BUG_ON(gnt_list_entry->gref == -ENOSPC); 377 if (info->feature_persistent) 378 grant_foreign_access(gnt_list_entry, info); 379 else { 380 /* Grant access to the GFN passed by the caller */ 381 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 382 info->xbdev->otherend_id, 383 gfn, 0); 384 } 385 386 return gnt_list_entry; 387 } 388 389 static struct grant *get_indirect_grant(grant_ref_t *gref_head, 390 struct blkfront_ring_info *rinfo) 391 { 392 struct grant *gnt_list_entry = get_free_grant(rinfo); 393 struct blkfront_info *info = rinfo->dev_info; 394 395 if (gnt_list_entry->gref != GRANT_INVALID_REF) 396 return gnt_list_entry; 397 398 /* Assign a gref to this page */ 399 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 400 BUG_ON(gnt_list_entry->gref == -ENOSPC); 401 if (!info->feature_persistent) { 402 struct page *indirect_page; 403 404 /* Fetch a pre-allocated page to use for indirect grefs */ 405 BUG_ON(list_empty(&rinfo->indirect_pages)); 406 indirect_page = list_first_entry(&rinfo->indirect_pages, 407 struct page, lru); 408 list_del(&indirect_page->lru); 409 gnt_list_entry->page = indirect_page; 410 } 411 grant_foreign_access(gnt_list_entry, info); 412 413 return gnt_list_entry; 414 } 415 416 static const char *op_name(int op) 417 { 418 static const char *const names[] = { 419 [BLKIF_OP_READ] = "read", 420 [BLKIF_OP_WRITE] = "write", 421 [BLKIF_OP_WRITE_BARRIER] = "barrier", 422 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 423 [BLKIF_OP_DISCARD] = "discard" }; 424 425 if (op < 0 || op >= ARRAY_SIZE(names)) 426 return "unknown"; 427 428 if (!names[op]) 429 return "reserved"; 430 431 return names[op]; 432 } 433 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 434 { 435 unsigned int end = minor + nr; 436 int rc; 437 438 if (end > nr_minors) { 439 unsigned long *bitmap, *old; 440 441 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 442 GFP_KERNEL); 443 if (bitmap == NULL) 444 return -ENOMEM; 445 446 spin_lock(&minor_lock); 447 if (end > nr_minors) { 448 old = minors; 449 memcpy(bitmap, minors, 450 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 451 minors = bitmap; 452 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 453 } else 454 old = bitmap; 455 spin_unlock(&minor_lock); 456 kfree(old); 457 } 458 459 spin_lock(&minor_lock); 460 if (find_next_bit(minors, end, minor) >= end) { 461 bitmap_set(minors, minor, nr); 462 rc = 0; 463 } else 464 rc = -EBUSY; 465 spin_unlock(&minor_lock); 466 467 return rc; 468 } 469 470 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 471 { 472 unsigned int end = minor + nr; 473 474 BUG_ON(end > nr_minors); 475 spin_lock(&minor_lock); 476 bitmap_clear(minors, minor, nr); 477 spin_unlock(&minor_lock); 478 } 479 480 static void blkif_restart_queue_callback(void *arg) 481 { 482 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg; 483 schedule_work(&rinfo->work); 484 } 485 486 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 487 { 488 /* We don't have real geometry info, but let's at least return 489 values consistent with the size of the device */ 490 sector_t nsect = get_capacity(bd->bd_disk); 491 sector_t cylinders = nsect; 492 493 hg->heads = 0xff; 494 hg->sectors = 0x3f; 495 sector_div(cylinders, hg->heads * hg->sectors); 496 hg->cylinders = cylinders; 497 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 498 hg->cylinders = 0xffff; 499 return 0; 500 } 501 502 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 503 unsigned command, unsigned long argument) 504 { 505 struct blkfront_info *info = bdev->bd_disk->private_data; 506 int i; 507 508 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 509 command, (long)argument); 510 511 switch (command) { 512 case CDROMMULTISESSION: 513 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 514 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 515 if (put_user(0, (char __user *)(argument + i))) 516 return -EFAULT; 517 return 0; 518 519 case CDROM_GET_CAPABILITY: { 520 struct gendisk *gd = info->gd; 521 if (gd->flags & GENHD_FL_CD) 522 return 0; 523 return -EINVAL; 524 } 525 526 default: 527 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 528 command);*/ 529 return -EINVAL; /* same return as native Linux */ 530 } 531 532 return 0; 533 } 534 535 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, 536 struct request *req, 537 struct blkif_request **ring_req) 538 { 539 unsigned long id; 540 541 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt); 542 rinfo->ring.req_prod_pvt++; 543 544 id = get_id_from_freelist(rinfo); 545 rinfo->shadow[id].request = req; 546 rinfo->shadow[id].status = REQ_WAITING; 547 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID; 548 549 (*ring_req)->u.rw.id = id; 550 551 return id; 552 } 553 554 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo) 555 { 556 struct blkfront_info *info = rinfo->dev_info; 557 struct blkif_request *ring_req; 558 unsigned long id; 559 560 /* Fill out a communications ring structure. */ 561 id = blkif_ring_get_request(rinfo, req, &ring_req); 562 563 ring_req->operation = BLKIF_OP_DISCARD; 564 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 565 ring_req->u.discard.id = id; 566 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 567 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard) 568 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 569 else 570 ring_req->u.discard.flag = 0; 571 572 /* Keep a private copy so we can reissue requests when recovering. */ 573 rinfo->shadow[id].req = *ring_req; 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 read 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 unsigned long id, extra_id = NO_ASSOCIATED_ID; 707 bool require_extra_req = false; 708 int i; 709 struct setup_rw_req setup = { 710 .grant_idx = 0, 711 .segments = NULL, 712 .rinfo = rinfo, 713 .need_copy = rq_data_dir(req) && info->feature_persistent, 714 }; 715 716 /* 717 * Used to store if we are able to queue the request by just using 718 * existing persistent grants, or if we have to get new grants, 719 * as there are not sufficiently many free. 720 */ 721 bool new_persistent_gnts = false; 722 struct scatterlist *sg; 723 int num_sg, max_grefs, num_grant; 724 725 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG; 726 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 727 /* 728 * If we are using indirect segments we need to account 729 * for the indirect grefs used in the request. 730 */ 731 max_grefs += INDIRECT_GREFS(max_grefs); 732 733 /* Check if we have enough persistent grants to allocate a requests */ 734 if (rinfo->persistent_gnts_c < max_grefs) { 735 new_persistent_gnts = true; 736 737 if (gnttab_alloc_grant_references( 738 max_grefs - rinfo->persistent_gnts_c, 739 &setup.gref_head) < 0) { 740 gnttab_request_free_callback( 741 &rinfo->callback, 742 blkif_restart_queue_callback, 743 rinfo, 744 max_grefs - rinfo->persistent_gnts_c); 745 return 1; 746 } 747 } 748 749 /* Fill out a communications ring structure. */ 750 id = blkif_ring_get_request(rinfo, req, &ring_req); 751 752 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg); 753 num_grant = 0; 754 /* Calculate the number of grant used */ 755 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) 756 num_grant += gnttab_count_grant(sg->offset, sg->length); 757 758 require_extra_req = info->max_indirect_segments == 0 && 759 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST; 760 BUG_ON(!HAS_EXTRA_REQ && require_extra_req); 761 762 rinfo->shadow[id].num_sg = num_sg; 763 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST && 764 likely(!require_extra_req)) { 765 /* 766 * The indirect operation can only be a BLKIF_OP_READ or 767 * BLKIF_OP_WRITE 768 */ 769 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA); 770 ring_req->operation = BLKIF_OP_INDIRECT; 771 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 772 BLKIF_OP_WRITE : BLKIF_OP_READ; 773 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 774 ring_req->u.indirect.handle = info->handle; 775 ring_req->u.indirect.nr_segments = num_grant; 776 } else { 777 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 778 ring_req->u.rw.handle = info->handle; 779 ring_req->operation = rq_data_dir(req) ? 780 BLKIF_OP_WRITE : BLKIF_OP_READ; 781 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) { 782 /* 783 * Ideally we can do an unordered flush-to-disk. 784 * In case the backend onlysupports barriers, use that. 785 * A barrier request a superset of FUA, so we can 786 * implement it the same way. (It's also a FLUSH+FUA, 787 * since it is guaranteed ordered WRT previous writes.) 788 */ 789 if (info->feature_flush && info->feature_fua) 790 ring_req->operation = 791 BLKIF_OP_WRITE_BARRIER; 792 else if (info->feature_flush) 793 ring_req->operation = 794 BLKIF_OP_FLUSH_DISKCACHE; 795 else 796 ring_req->operation = 0; 797 } 798 ring_req->u.rw.nr_segments = num_grant; 799 if (unlikely(require_extra_req)) { 800 extra_id = blkif_ring_get_request(rinfo, req, 801 &extra_ring_req); 802 /* 803 * Only the first request contains the scatter-gather 804 * list. 805 */ 806 rinfo->shadow[extra_id].num_sg = 0; 807 808 blkif_setup_extra_req(ring_req, extra_ring_req); 809 810 /* Link the 2 requests together */ 811 rinfo->shadow[extra_id].associated_id = id; 812 rinfo->shadow[id].associated_id = extra_id; 813 } 814 } 815 816 setup.ring_req = ring_req; 817 setup.id = id; 818 819 setup.require_extra_req = require_extra_req; 820 if (unlikely(require_extra_req)) 821 setup.extra_ring_req = extra_ring_req; 822 823 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) { 824 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 825 826 if (setup.need_copy) { 827 setup.bvec_off = sg->offset; 828 setup.bvec_data = kmap_atomic(sg_page(sg)); 829 } 830 831 gnttab_foreach_grant_in_range(sg_page(sg), 832 sg->offset, 833 sg->length, 834 blkif_setup_rw_req_grant, 835 &setup); 836 837 if (setup.need_copy) 838 kunmap_atomic(setup.bvec_data); 839 } 840 if (setup.segments) 841 kunmap_atomic(setup.segments); 842 843 /* Keep a private copy so we can reissue requests when recovering. */ 844 rinfo->shadow[id].req = *ring_req; 845 if (unlikely(require_extra_req)) 846 rinfo->shadow[extra_id].req = *extra_ring_req; 847 848 if (new_persistent_gnts) 849 gnttab_free_grant_references(setup.gref_head); 850 851 return 0; 852 } 853 854 /* 855 * Generate a Xen blkfront IO request from a blk layer request. Reads 856 * and writes are handled as expected. 857 * 858 * @req: a request struct 859 */ 860 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo) 861 { 862 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED)) 863 return 1; 864 865 if (unlikely(req_op(req) == REQ_OP_DISCARD || 866 req_op(req) == REQ_OP_SECURE_ERASE)) 867 return blkif_queue_discard_req(req, rinfo); 868 else 869 return blkif_queue_rw_req(req, rinfo); 870 } 871 872 static inline void flush_requests(struct blkfront_ring_info *rinfo) 873 { 874 int notify; 875 876 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify); 877 878 if (notify) 879 notify_remote_via_irq(rinfo->irq); 880 } 881 882 static inline bool blkif_request_flush_invalid(struct request *req, 883 struct blkfront_info *info) 884 { 885 return (blk_rq_is_passthrough(req) || 886 ((req_op(req) == REQ_OP_FLUSH) && 887 !info->feature_flush) || 888 ((req->cmd_flags & REQ_FUA) && 889 !info->feature_fua)); 890 } 891 892 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx, 893 const struct blk_mq_queue_data *qd) 894 { 895 unsigned long flags; 896 int qid = hctx->queue_num; 897 struct blkfront_info *info = hctx->queue->queuedata; 898 struct blkfront_ring_info *rinfo = NULL; 899 900 rinfo = get_rinfo(info, qid); 901 blk_mq_start_request(qd->rq); 902 spin_lock_irqsave(&rinfo->ring_lock, flags); 903 if (RING_FULL(&rinfo->ring)) 904 goto out_busy; 905 906 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info)) 907 goto out_err; 908 909 if (blkif_queue_request(qd->rq, rinfo)) 910 goto out_busy; 911 912 flush_requests(rinfo); 913 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 914 return BLK_STS_OK; 915 916 out_err: 917 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 918 return BLK_STS_IOERR; 919 920 out_busy: 921 blk_mq_stop_hw_queue(hctx); 922 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 923 return BLK_STS_DEV_RESOURCE; 924 } 925 926 static void blkif_complete_rq(struct request *rq) 927 { 928 blk_mq_end_request(rq, blkif_req(rq)->error); 929 } 930 931 static const struct blk_mq_ops blkfront_mq_ops = { 932 .queue_rq = blkif_queue_rq, 933 .complete = blkif_complete_rq, 934 }; 935 936 static void blkif_set_queue_limits(struct blkfront_info *info) 937 { 938 struct request_queue *rq = info->rq; 939 struct gendisk *gd = info->gd; 940 unsigned int segments = info->max_indirect_segments ? : 941 BLKIF_MAX_SEGMENTS_PER_REQUEST; 942 943 blk_queue_flag_set(QUEUE_FLAG_VIRT, rq); 944 945 if (info->feature_discard) { 946 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq); 947 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 948 rq->limits.discard_granularity = info->discard_granularity ?: 949 info->physical_sector_size; 950 rq->limits.discard_alignment = info->discard_alignment; 951 if (info->feature_secdiscard) 952 blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq); 953 } 954 955 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 956 blk_queue_logical_block_size(rq, info->sector_size); 957 blk_queue_physical_block_size(rq, info->physical_sector_size); 958 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512); 959 960 /* Each segment in a request is up to an aligned page in size. */ 961 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 962 blk_queue_max_segment_size(rq, PAGE_SIZE); 963 964 /* Ensure a merged request will fit in a single I/O ring slot. */ 965 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG); 966 967 /* Make sure buffer addresses are sector-aligned. */ 968 blk_queue_dma_alignment(rq, 511); 969 } 970 971 static const char *flush_info(struct blkfront_info *info) 972 { 973 if (info->feature_flush && info->feature_fua) 974 return "barrier: enabled;"; 975 else if (info->feature_flush) 976 return "flush diskcache: enabled;"; 977 else 978 return "barrier or flush: disabled;"; 979 } 980 981 static void xlvbd_flush(struct blkfront_info *info) 982 { 983 blk_queue_write_cache(info->rq, info->feature_flush ? true : false, 984 info->feature_fua ? true : false); 985 pr_info("blkfront: %s: %s %s %s %s %s\n", 986 info->gd->disk_name, flush_info(info), 987 "persistent grants:", info->feature_persistent ? 988 "enabled;" : "disabled;", "indirect descriptors:", 989 info->max_indirect_segments ? "enabled;" : "disabled;"); 990 } 991 992 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 993 { 994 int major; 995 major = BLKIF_MAJOR(vdevice); 996 *minor = BLKIF_MINOR(vdevice); 997 switch (major) { 998 case XEN_IDE0_MAJOR: 999 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 1000 *minor = ((*minor / 64) * PARTS_PER_DISK) + 1001 EMULATED_HD_DISK_MINOR_OFFSET; 1002 break; 1003 case XEN_IDE1_MAJOR: 1004 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 1005 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 1006 EMULATED_HD_DISK_MINOR_OFFSET; 1007 break; 1008 case XEN_SCSI_DISK0_MAJOR: 1009 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 1010 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 1011 break; 1012 case XEN_SCSI_DISK1_MAJOR: 1013 case XEN_SCSI_DISK2_MAJOR: 1014 case XEN_SCSI_DISK3_MAJOR: 1015 case XEN_SCSI_DISK4_MAJOR: 1016 case XEN_SCSI_DISK5_MAJOR: 1017 case XEN_SCSI_DISK6_MAJOR: 1018 case XEN_SCSI_DISK7_MAJOR: 1019 *offset = (*minor / PARTS_PER_DISK) + 1020 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 1021 EMULATED_SD_DISK_NAME_OFFSET; 1022 *minor = *minor + 1023 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 1024 EMULATED_SD_DISK_MINOR_OFFSET; 1025 break; 1026 case XEN_SCSI_DISK8_MAJOR: 1027 case XEN_SCSI_DISK9_MAJOR: 1028 case XEN_SCSI_DISK10_MAJOR: 1029 case XEN_SCSI_DISK11_MAJOR: 1030 case XEN_SCSI_DISK12_MAJOR: 1031 case XEN_SCSI_DISK13_MAJOR: 1032 case XEN_SCSI_DISK14_MAJOR: 1033 case XEN_SCSI_DISK15_MAJOR: 1034 *offset = (*minor / PARTS_PER_DISK) + 1035 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 1036 EMULATED_SD_DISK_NAME_OFFSET; 1037 *minor = *minor + 1038 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 1039 EMULATED_SD_DISK_MINOR_OFFSET; 1040 break; 1041 case XENVBD_MAJOR: 1042 *offset = *minor / PARTS_PER_DISK; 1043 break; 1044 default: 1045 printk(KERN_WARNING "blkfront: your disk configuration is " 1046 "incorrect, please use an xvd device instead\n"); 1047 return -ENODEV; 1048 } 1049 return 0; 1050 } 1051 1052 static char *encode_disk_name(char *ptr, unsigned int n) 1053 { 1054 if (n >= 26) 1055 ptr = encode_disk_name(ptr, n / 26 - 1); 1056 *ptr = 'a' + n % 26; 1057 return ptr + 1; 1058 } 1059 1060 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 1061 struct blkfront_info *info, 1062 u16 vdisk_info, u16 sector_size, 1063 unsigned int physical_sector_size) 1064 { 1065 struct gendisk *gd; 1066 int nr_minors = 1; 1067 int err; 1068 unsigned int offset; 1069 int minor; 1070 int nr_parts; 1071 char *ptr; 1072 1073 BUG_ON(info->gd != NULL); 1074 BUG_ON(info->rq != NULL); 1075 1076 if ((info->vdevice>>EXT_SHIFT) > 1) { 1077 /* this is above the extended range; something is wrong */ 1078 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 1079 return -ENODEV; 1080 } 1081 1082 if (!VDEV_IS_EXTENDED(info->vdevice)) { 1083 err = xen_translate_vdev(info->vdevice, &minor, &offset); 1084 if (err) 1085 return err; 1086 nr_parts = PARTS_PER_DISK; 1087 } else { 1088 minor = BLKIF_MINOR_EXT(info->vdevice); 1089 nr_parts = PARTS_PER_EXT_DISK; 1090 offset = minor / nr_parts; 1091 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 1092 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 1093 "emulated IDE disks,\n\t choose an xvd device name" 1094 "from xvde on\n", info->vdevice); 1095 } 1096 if (minor >> MINORBITS) { 1097 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 1098 info->vdevice, minor); 1099 return -ENODEV; 1100 } 1101 1102 if ((minor % nr_parts) == 0) 1103 nr_minors = nr_parts; 1104 1105 err = xlbd_reserve_minors(minor, nr_minors); 1106 if (err) 1107 return err; 1108 err = -ENODEV; 1109 1110 memset(&info->tag_set, 0, sizeof(info->tag_set)); 1111 info->tag_set.ops = &blkfront_mq_ops; 1112 info->tag_set.nr_hw_queues = info->nr_rings; 1113 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) { 1114 /* 1115 * When indirect descriptior is not supported, the I/O request 1116 * will be split between multiple request in the ring. 1117 * To avoid problems when sending the request, divide by 1118 * 2 the depth of the queue. 1119 */ 1120 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2; 1121 } else 1122 info->tag_set.queue_depth = BLK_RING_SIZE(info); 1123 info->tag_set.numa_node = NUMA_NO_NODE; 1124 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE; 1125 info->tag_set.cmd_size = sizeof(struct blkif_req); 1126 info->tag_set.driver_data = info; 1127 1128 err = blk_mq_alloc_tag_set(&info->tag_set); 1129 if (err) 1130 goto out_release_minors; 1131 1132 gd = blk_mq_alloc_disk(&info->tag_set, info); 1133 if (IS_ERR(gd)) { 1134 err = PTR_ERR(gd); 1135 goto out_free_tag_set; 1136 } 1137 1138 strcpy(gd->disk_name, DEV_NAME); 1139 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 1140 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 1141 if (nr_minors > 1) 1142 *ptr = 0; 1143 else 1144 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 1145 "%d", minor & (nr_parts - 1)); 1146 1147 gd->major = XENVBD_MAJOR; 1148 gd->first_minor = minor; 1149 gd->minors = nr_minors; 1150 gd->fops = &xlvbd_block_fops; 1151 gd->private_data = info; 1152 set_capacity(gd, capacity); 1153 1154 info->rq = gd->queue; 1155 info->gd = gd; 1156 info->sector_size = sector_size; 1157 info->physical_sector_size = physical_sector_size; 1158 blkif_set_queue_limits(info); 1159 1160 xlvbd_flush(info); 1161 1162 if (vdisk_info & VDISK_READONLY) 1163 set_disk_ro(gd, 1); 1164 1165 if (vdisk_info & VDISK_REMOVABLE) 1166 gd->flags |= GENHD_FL_REMOVABLE; 1167 1168 if (vdisk_info & VDISK_CDROM) 1169 gd->flags |= GENHD_FL_CD; 1170 1171 return 0; 1172 1173 out_free_tag_set: 1174 blk_mq_free_tag_set(&info->tag_set); 1175 out_release_minors: 1176 xlbd_release_minors(minor, nr_minors); 1177 return err; 1178 } 1179 1180 static void xlvbd_release_gendisk(struct blkfront_info *info) 1181 { 1182 unsigned int minor, nr_minors, i; 1183 struct blkfront_ring_info *rinfo; 1184 1185 if (info->rq == NULL) 1186 return; 1187 1188 /* No more blkif_request(). */ 1189 blk_mq_stop_hw_queues(info->rq); 1190 1191 for_each_rinfo(info, rinfo, i) { 1192 /* No more gnttab callback work. */ 1193 gnttab_cancel_free_callback(&rinfo->callback); 1194 1195 /* Flush gnttab callback work. Must be done with no locks held. */ 1196 flush_work(&rinfo->work); 1197 } 1198 1199 del_gendisk(info->gd); 1200 1201 minor = info->gd->first_minor; 1202 nr_minors = info->gd->minors; 1203 xlbd_release_minors(minor, nr_minors); 1204 1205 blk_cleanup_disk(info->gd); 1206 info->gd = NULL; 1207 blk_mq_free_tag_set(&info->tag_set); 1208 } 1209 1210 /* Already hold rinfo->ring_lock. */ 1211 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo) 1212 { 1213 if (!RING_FULL(&rinfo->ring)) 1214 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true); 1215 } 1216 1217 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo) 1218 { 1219 unsigned long flags; 1220 1221 spin_lock_irqsave(&rinfo->ring_lock, flags); 1222 kick_pending_request_queues_locked(rinfo); 1223 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1224 } 1225 1226 static void blkif_restart_queue(struct work_struct *work) 1227 { 1228 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work); 1229 1230 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED) 1231 kick_pending_request_queues(rinfo); 1232 } 1233 1234 static void blkif_free_ring(struct blkfront_ring_info *rinfo) 1235 { 1236 struct grant *persistent_gnt, *n; 1237 struct blkfront_info *info = rinfo->dev_info; 1238 int i, j, segs; 1239 1240 /* 1241 * Remove indirect pages, this only happens when using indirect 1242 * descriptors but not persistent grants 1243 */ 1244 if (!list_empty(&rinfo->indirect_pages)) { 1245 struct page *indirect_page, *n; 1246 1247 BUG_ON(info->feature_persistent); 1248 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 1249 list_del(&indirect_page->lru); 1250 __free_page(indirect_page); 1251 } 1252 } 1253 1254 /* Remove all persistent grants. */ 1255 if (!list_empty(&rinfo->grants)) { 1256 list_for_each_entry_safe(persistent_gnt, n, 1257 &rinfo->grants, node) { 1258 list_del(&persistent_gnt->node); 1259 if (persistent_gnt->gref != GRANT_INVALID_REF) { 1260 gnttab_end_foreign_access(persistent_gnt->gref, 1261 0, 0UL); 1262 rinfo->persistent_gnts_c--; 1263 } 1264 if (info->feature_persistent) 1265 __free_page(persistent_gnt->page); 1266 kfree(persistent_gnt); 1267 } 1268 } 1269 BUG_ON(rinfo->persistent_gnts_c != 0); 1270 1271 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1272 /* 1273 * Clear persistent grants present in requests already 1274 * on the shared ring 1275 */ 1276 if (!rinfo->shadow[i].request) 1277 goto free_shadow; 1278 1279 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 1280 rinfo->shadow[i].req.u.indirect.nr_segments : 1281 rinfo->shadow[i].req.u.rw.nr_segments; 1282 for (j = 0; j < segs; j++) { 1283 persistent_gnt = rinfo->shadow[i].grants_used[j]; 1284 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1285 if (info->feature_persistent) 1286 __free_page(persistent_gnt->page); 1287 kfree(persistent_gnt); 1288 } 1289 1290 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT) 1291 /* 1292 * If this is not an indirect operation don't try to 1293 * free indirect segments 1294 */ 1295 goto free_shadow; 1296 1297 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 1298 persistent_gnt = rinfo->shadow[i].indirect_grants[j]; 1299 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1300 __free_page(persistent_gnt->page); 1301 kfree(persistent_gnt); 1302 } 1303 1304 free_shadow: 1305 kvfree(rinfo->shadow[i].grants_used); 1306 rinfo->shadow[i].grants_used = NULL; 1307 kvfree(rinfo->shadow[i].indirect_grants); 1308 rinfo->shadow[i].indirect_grants = NULL; 1309 kvfree(rinfo->shadow[i].sg); 1310 rinfo->shadow[i].sg = NULL; 1311 } 1312 1313 /* No more gnttab callback work. */ 1314 gnttab_cancel_free_callback(&rinfo->callback); 1315 1316 /* Flush gnttab callback work. Must be done with no locks held. */ 1317 flush_work(&rinfo->work); 1318 1319 /* Free resources associated with old device channel. */ 1320 for (i = 0; i < info->nr_ring_pages; i++) { 1321 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) { 1322 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0); 1323 rinfo->ring_ref[i] = GRANT_INVALID_REF; 1324 } 1325 } 1326 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE)); 1327 rinfo->ring.sring = NULL; 1328 1329 if (rinfo->irq) 1330 unbind_from_irqhandler(rinfo->irq, rinfo); 1331 rinfo->evtchn = rinfo->irq = 0; 1332 } 1333 1334 static void blkif_free(struct blkfront_info *info, int suspend) 1335 { 1336 unsigned int i; 1337 struct blkfront_ring_info *rinfo; 1338 1339 /* Prevent new requests being issued until we fix things up. */ 1340 info->connected = suspend ? 1341 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 1342 /* No more blkif_request(). */ 1343 if (info->rq) 1344 blk_mq_stop_hw_queues(info->rq); 1345 1346 for_each_rinfo(info, rinfo, i) 1347 blkif_free_ring(rinfo); 1348 1349 kvfree(info->rinfo); 1350 info->rinfo = NULL; 1351 info->nr_rings = 0; 1352 } 1353 1354 struct copy_from_grant { 1355 const struct blk_shadow *s; 1356 unsigned int grant_idx; 1357 unsigned int bvec_offset; 1358 char *bvec_data; 1359 }; 1360 1361 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset, 1362 unsigned int len, void *data) 1363 { 1364 struct copy_from_grant *info = data; 1365 char *shared_data; 1366 /* Convenient aliases */ 1367 const struct blk_shadow *s = info->s; 1368 1369 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page); 1370 1371 memcpy(info->bvec_data + info->bvec_offset, 1372 shared_data + offset, len); 1373 1374 info->bvec_offset += len; 1375 info->grant_idx++; 1376 1377 kunmap_atomic(shared_data); 1378 } 1379 1380 static enum blk_req_status blkif_rsp_to_req_status(int rsp) 1381 { 1382 switch (rsp) 1383 { 1384 case BLKIF_RSP_OKAY: 1385 return REQ_DONE; 1386 case BLKIF_RSP_EOPNOTSUPP: 1387 return REQ_EOPNOTSUPP; 1388 case BLKIF_RSP_ERROR: 1389 default: 1390 return REQ_ERROR; 1391 } 1392 } 1393 1394 /* 1395 * Get the final status of the block request based on two ring response 1396 */ 1397 static int blkif_get_final_status(enum blk_req_status s1, 1398 enum blk_req_status s2) 1399 { 1400 BUG_ON(s1 == REQ_WAITING); 1401 BUG_ON(s2 == REQ_WAITING); 1402 1403 if (s1 == REQ_ERROR || s2 == REQ_ERROR) 1404 return BLKIF_RSP_ERROR; 1405 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP) 1406 return BLKIF_RSP_EOPNOTSUPP; 1407 return BLKIF_RSP_OKAY; 1408 } 1409 1410 static bool blkif_completion(unsigned long *id, 1411 struct blkfront_ring_info *rinfo, 1412 struct blkif_response *bret) 1413 { 1414 int i = 0; 1415 struct scatterlist *sg; 1416 int num_sg, num_grant; 1417 struct blkfront_info *info = rinfo->dev_info; 1418 struct blk_shadow *s = &rinfo->shadow[*id]; 1419 struct copy_from_grant data = { 1420 .grant_idx = 0, 1421 }; 1422 1423 num_grant = s->req.operation == BLKIF_OP_INDIRECT ? 1424 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1425 1426 /* The I/O request may be split in two. */ 1427 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) { 1428 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id]; 1429 1430 /* Keep the status of the current response in shadow. */ 1431 s->status = blkif_rsp_to_req_status(bret->status); 1432 1433 /* Wait the second response if not yet here. */ 1434 if (s2->status == REQ_WAITING) 1435 return false; 1436 1437 bret->status = blkif_get_final_status(s->status, 1438 s2->status); 1439 1440 /* 1441 * All the grants is stored in the first shadow in order 1442 * to make the completion code simpler. 1443 */ 1444 num_grant += s2->req.u.rw.nr_segments; 1445 1446 /* 1447 * The two responses may not come in order. Only the 1448 * first request will store the scatter-gather list. 1449 */ 1450 if (s2->num_sg != 0) { 1451 /* Update "id" with the ID of the first response. */ 1452 *id = s->associated_id; 1453 s = s2; 1454 } 1455 1456 /* 1457 * We don't need anymore the second request, so recycling 1458 * it now. 1459 */ 1460 if (add_id_to_freelist(rinfo, s->associated_id)) 1461 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n", 1462 info->gd->disk_name, s->associated_id); 1463 } 1464 1465 data.s = s; 1466 num_sg = s->num_sg; 1467 1468 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { 1469 for_each_sg(s->sg, sg, num_sg, i) { 1470 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1471 1472 data.bvec_offset = sg->offset; 1473 data.bvec_data = kmap_atomic(sg_page(sg)); 1474 1475 gnttab_foreach_grant_in_range(sg_page(sg), 1476 sg->offset, 1477 sg->length, 1478 blkif_copy_from_grant, 1479 &data); 1480 1481 kunmap_atomic(data.bvec_data); 1482 } 1483 } 1484 /* Add the persistent grant into the list of free grants */ 1485 for (i = 0; i < num_grant; i++) { 1486 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) { 1487 /* 1488 * If the grant is still mapped by the backend (the 1489 * backend has chosen to make this grant persistent) 1490 * we add it at the head of the list, so it will be 1491 * reused first. 1492 */ 1493 if (!info->feature_persistent) 1494 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1495 s->grants_used[i]->gref); 1496 list_add(&s->grants_used[i]->node, &rinfo->grants); 1497 rinfo->persistent_gnts_c++; 1498 } else { 1499 /* 1500 * If the grant is not mapped by the backend we end the 1501 * foreign access and add it to the tail of the list, 1502 * so it will not be picked again unless we run out of 1503 * persistent grants. 1504 */ 1505 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); 1506 s->grants_used[i]->gref = GRANT_INVALID_REF; 1507 list_add_tail(&s->grants_used[i]->node, &rinfo->grants); 1508 } 1509 } 1510 if (s->req.operation == BLKIF_OP_INDIRECT) { 1511 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) { 1512 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { 1513 if (!info->feature_persistent) 1514 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1515 s->indirect_grants[i]->gref); 1516 list_add(&s->indirect_grants[i]->node, &rinfo->grants); 1517 rinfo->persistent_gnts_c++; 1518 } else { 1519 struct page *indirect_page; 1520 1521 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); 1522 /* 1523 * Add the used indirect page back to the list of 1524 * available pages for indirect grefs. 1525 */ 1526 if (!info->feature_persistent) { 1527 indirect_page = s->indirect_grants[i]->page; 1528 list_add(&indirect_page->lru, &rinfo->indirect_pages); 1529 } 1530 s->indirect_grants[i]->gref = GRANT_INVALID_REF; 1531 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants); 1532 } 1533 } 1534 } 1535 1536 return true; 1537 } 1538 1539 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1540 { 1541 struct request *req; 1542 struct blkif_response *bret; 1543 RING_IDX i, rp; 1544 unsigned long flags; 1545 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id; 1546 struct blkfront_info *info = rinfo->dev_info; 1547 1548 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 1549 return IRQ_HANDLED; 1550 1551 spin_lock_irqsave(&rinfo->ring_lock, flags); 1552 again: 1553 rp = rinfo->ring.sring->rsp_prod; 1554 rmb(); /* Ensure we see queued responses up to 'rp'. */ 1555 1556 for (i = rinfo->ring.rsp_cons; i != rp; i++) { 1557 unsigned long id; 1558 1559 bret = RING_GET_RESPONSE(&rinfo->ring, i); 1560 id = bret->id; 1561 /* 1562 * The backend has messed up and given us an id that we would 1563 * never have given to it (we stamp it up to BLK_RING_SIZE - 1564 * look in get_id_from_freelist. 1565 */ 1566 if (id >= BLK_RING_SIZE(info)) { 1567 WARN(1, "%s: response to %s has incorrect id (%ld)\n", 1568 info->gd->disk_name, op_name(bret->operation), id); 1569 /* We can't safely get the 'struct request' as 1570 * the id is busted. */ 1571 continue; 1572 } 1573 req = rinfo->shadow[id].request; 1574 1575 if (bret->operation != BLKIF_OP_DISCARD) { 1576 /* 1577 * We may need to wait for an extra response if the 1578 * I/O request is split in 2 1579 */ 1580 if (!blkif_completion(&id, rinfo, bret)) 1581 continue; 1582 } 1583 1584 if (add_id_to_freelist(rinfo, id)) { 1585 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1586 info->gd->disk_name, op_name(bret->operation), id); 1587 continue; 1588 } 1589 1590 if (bret->status == BLKIF_RSP_OKAY) 1591 blkif_req(req)->error = BLK_STS_OK; 1592 else 1593 blkif_req(req)->error = BLK_STS_IOERR; 1594 1595 switch (bret->operation) { 1596 case BLKIF_OP_DISCARD: 1597 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1598 struct request_queue *rq = info->rq; 1599 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1600 info->gd->disk_name, op_name(bret->operation)); 1601 blkif_req(req)->error = BLK_STS_NOTSUPP; 1602 info->feature_discard = 0; 1603 info->feature_secdiscard = 0; 1604 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 1605 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq); 1606 } 1607 break; 1608 case BLKIF_OP_FLUSH_DISKCACHE: 1609 case BLKIF_OP_WRITE_BARRIER: 1610 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1611 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1612 info->gd->disk_name, op_name(bret->operation)); 1613 blkif_req(req)->error = BLK_STS_NOTSUPP; 1614 } 1615 if (unlikely(bret->status == BLKIF_RSP_ERROR && 1616 rinfo->shadow[id].req.u.rw.nr_segments == 0)) { 1617 printk(KERN_WARNING "blkfront: %s: empty %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(blkif_req(req)->error)) { 1622 if (blkif_req(req)->error == BLK_STS_NOTSUPP) 1623 blkif_req(req)->error = BLK_STS_OK; 1624 info->feature_fua = 0; 1625 info->feature_flush = 0; 1626 xlvbd_flush(info); 1627 } 1628 fallthrough; 1629 case BLKIF_OP_READ: 1630 case BLKIF_OP_WRITE: 1631 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 1632 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 1633 "request: %x\n", bret->status); 1634 1635 break; 1636 default: 1637 BUG(); 1638 } 1639 1640 if (likely(!blk_should_fake_timeout(req->q))) 1641 blk_mq_complete_request(req); 1642 } 1643 1644 rinfo->ring.rsp_cons = i; 1645 1646 if (i != rinfo->ring.req_prod_pvt) { 1647 int more_to_do; 1648 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do); 1649 if (more_to_do) 1650 goto again; 1651 } else 1652 rinfo->ring.sring->rsp_event = i + 1; 1653 1654 kick_pending_request_queues_locked(rinfo); 1655 1656 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1657 1658 return IRQ_HANDLED; 1659 } 1660 1661 1662 static int setup_blkring(struct xenbus_device *dev, 1663 struct blkfront_ring_info *rinfo) 1664 { 1665 struct blkif_sring *sring; 1666 int err, i; 1667 struct blkfront_info *info = rinfo->dev_info; 1668 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE; 1669 grant_ref_t gref[XENBUS_MAX_RING_GRANTS]; 1670 1671 for (i = 0; i < info->nr_ring_pages; i++) 1672 rinfo->ring_ref[i] = GRANT_INVALID_REF; 1673 1674 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH, 1675 get_order(ring_size)); 1676 if (!sring) { 1677 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1678 return -ENOMEM; 1679 } 1680 SHARED_RING_INIT(sring); 1681 FRONT_RING_INIT(&rinfo->ring, sring, ring_size); 1682 1683 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref); 1684 if (err < 0) { 1685 free_pages((unsigned long)sring, get_order(ring_size)); 1686 rinfo->ring.sring = NULL; 1687 goto fail; 1688 } 1689 for (i = 0; i < info->nr_ring_pages; i++) 1690 rinfo->ring_ref[i] = gref[i]; 1691 1692 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn); 1693 if (err) 1694 goto fail; 1695 1696 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0, 1697 "blkif", rinfo); 1698 if (err <= 0) { 1699 xenbus_dev_fatal(dev, err, 1700 "bind_evtchn_to_irqhandler failed"); 1701 goto fail; 1702 } 1703 rinfo->irq = err; 1704 1705 return 0; 1706 fail: 1707 blkif_free(info, 0); 1708 return err; 1709 } 1710 1711 /* 1712 * Write out per-ring/queue nodes including ring-ref and event-channel, and each 1713 * ring buffer may have multi pages depending on ->nr_ring_pages. 1714 */ 1715 static int write_per_ring_nodes(struct xenbus_transaction xbt, 1716 struct blkfront_ring_info *rinfo, const char *dir) 1717 { 1718 int err; 1719 unsigned int i; 1720 const char *message = NULL; 1721 struct blkfront_info *info = rinfo->dev_info; 1722 1723 if (info->nr_ring_pages == 1) { 1724 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]); 1725 if (err) { 1726 message = "writing ring-ref"; 1727 goto abort_transaction; 1728 } 1729 } else { 1730 for (i = 0; i < info->nr_ring_pages; i++) { 1731 char ring_ref_name[RINGREF_NAME_LEN]; 1732 1733 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 1734 err = xenbus_printf(xbt, dir, ring_ref_name, 1735 "%u", rinfo->ring_ref[i]); 1736 if (err) { 1737 message = "writing ring-ref"; 1738 goto abort_transaction; 1739 } 1740 } 1741 } 1742 1743 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn); 1744 if (err) { 1745 message = "writing event-channel"; 1746 goto abort_transaction; 1747 } 1748 1749 return 0; 1750 1751 abort_transaction: 1752 xenbus_transaction_end(xbt, 1); 1753 if (message) 1754 xenbus_dev_fatal(info->xbdev, err, "%s", message); 1755 1756 return err; 1757 } 1758 1759 static void free_info(struct blkfront_info *info) 1760 { 1761 list_del(&info->info_list); 1762 kfree(info); 1763 } 1764 1765 /* Common code used when first setting up, and when resuming. */ 1766 static int talk_to_blkback(struct xenbus_device *dev, 1767 struct blkfront_info *info) 1768 { 1769 const char *message = NULL; 1770 struct xenbus_transaction xbt; 1771 int err; 1772 unsigned int i, max_page_order; 1773 unsigned int ring_page_order; 1774 struct blkfront_ring_info *rinfo; 1775 1776 if (!info) 1777 return -ENODEV; 1778 1779 max_page_order = xenbus_read_unsigned(info->xbdev->otherend, 1780 "max-ring-page-order", 0); 1781 ring_page_order = min(xen_blkif_max_ring_order, max_page_order); 1782 info->nr_ring_pages = 1 << ring_page_order; 1783 1784 err = negotiate_mq(info); 1785 if (err) 1786 goto destroy_blkring; 1787 1788 for_each_rinfo(info, rinfo, i) { 1789 /* Create shared ring, alloc event channel. */ 1790 err = setup_blkring(dev, rinfo); 1791 if (err) 1792 goto destroy_blkring; 1793 } 1794 1795 again: 1796 err = xenbus_transaction_start(&xbt); 1797 if (err) { 1798 xenbus_dev_fatal(dev, err, "starting transaction"); 1799 goto destroy_blkring; 1800 } 1801 1802 if (info->nr_ring_pages > 1) { 1803 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u", 1804 ring_page_order); 1805 if (err) { 1806 message = "writing ring-page-order"; 1807 goto abort_transaction; 1808 } 1809 } 1810 1811 /* We already got the number of queues/rings in _probe */ 1812 if (info->nr_rings == 1) { 1813 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename); 1814 if (err) 1815 goto destroy_blkring; 1816 } else { 1817 char *path; 1818 size_t pathsize; 1819 1820 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u", 1821 info->nr_rings); 1822 if (err) { 1823 message = "writing multi-queue-num-queues"; 1824 goto abort_transaction; 1825 } 1826 1827 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN; 1828 path = kmalloc(pathsize, GFP_KERNEL); 1829 if (!path) { 1830 err = -ENOMEM; 1831 message = "ENOMEM while writing ring references"; 1832 goto abort_transaction; 1833 } 1834 1835 for_each_rinfo(info, rinfo, i) { 1836 memset(path, 0, pathsize); 1837 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i); 1838 err = write_per_ring_nodes(xbt, rinfo, path); 1839 if (err) { 1840 kfree(path); 1841 goto destroy_blkring; 1842 } 1843 } 1844 kfree(path); 1845 } 1846 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1847 XEN_IO_PROTO_ABI_NATIVE); 1848 if (err) { 1849 message = "writing protocol"; 1850 goto abort_transaction; 1851 } 1852 err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1853 info->feature_persistent); 1854 if (err) 1855 dev_warn(&dev->dev, 1856 "writing persistent grants feature to xenbus"); 1857 1858 err = xenbus_transaction_end(xbt, 0); 1859 if (err) { 1860 if (err == -EAGAIN) 1861 goto again; 1862 xenbus_dev_fatal(dev, err, "completing transaction"); 1863 goto destroy_blkring; 1864 } 1865 1866 for_each_rinfo(info, rinfo, i) { 1867 unsigned int j; 1868 1869 for (j = 0; j < BLK_RING_SIZE(info); j++) 1870 rinfo->shadow[j].req.u.rw.id = j + 1; 1871 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 1872 } 1873 xenbus_switch_state(dev, XenbusStateInitialised); 1874 1875 return 0; 1876 1877 abort_transaction: 1878 xenbus_transaction_end(xbt, 1); 1879 if (message) 1880 xenbus_dev_fatal(dev, err, "%s", message); 1881 destroy_blkring: 1882 blkif_free(info, 0); 1883 1884 mutex_lock(&blkfront_mutex); 1885 free_info(info); 1886 mutex_unlock(&blkfront_mutex); 1887 1888 dev_set_drvdata(&dev->dev, NULL); 1889 1890 return err; 1891 } 1892 1893 static 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 /* Enable the persistent grants feature. */ 1929 static bool feature_persistent = true; 1930 module_param(feature_persistent, bool, 0644); 1931 MODULE_PARM_DESC(feature_persistent, 1932 "Enables the persistent grants feature"); 1933 1934 /* 1935 * Entry point to this code when a new device is created. Allocate the basic 1936 * structures and the ring buffer for communication with the backend, and 1937 * inform the backend of the appropriate details for those. Switch to 1938 * Initialised state. 1939 */ 1940 static int blkfront_probe(struct xenbus_device *dev, 1941 const struct xenbus_device_id *id) 1942 { 1943 int err, vdevice; 1944 struct blkfront_info *info; 1945 1946 /* FIXME: Use dynamic device id if this is not set. */ 1947 err = xenbus_scanf(XBT_NIL, dev->nodename, 1948 "virtual-device", "%i", &vdevice); 1949 if (err != 1) { 1950 /* go looking in the extended area instead */ 1951 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1952 "%i", &vdevice); 1953 if (err != 1) { 1954 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1955 return err; 1956 } 1957 } 1958 1959 if (xen_hvm_domain()) { 1960 char *type; 1961 int len; 1962 /* no unplug has been done: do not hook devices != xen vbds */ 1963 if (xen_has_pv_and_legacy_disk_devices()) { 1964 int major; 1965 1966 if (!VDEV_IS_EXTENDED(vdevice)) 1967 major = BLKIF_MAJOR(vdevice); 1968 else 1969 major = XENVBD_MAJOR; 1970 1971 if (major != XENVBD_MAJOR) { 1972 printk(KERN_INFO 1973 "%s: HVM does not support vbd %d as xen block device\n", 1974 __func__, vdevice); 1975 return -ENODEV; 1976 } 1977 } 1978 /* do not create a PV cdrom device if we are an HVM guest */ 1979 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1980 if (IS_ERR(type)) 1981 return -ENODEV; 1982 if (strncmp(type, "cdrom", 5) == 0) { 1983 kfree(type); 1984 return -ENODEV; 1985 } 1986 kfree(type); 1987 } 1988 info = kzalloc(sizeof(*info), GFP_KERNEL); 1989 if (!info) { 1990 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1991 return -ENOMEM; 1992 } 1993 1994 info->xbdev = dev; 1995 1996 mutex_init(&info->mutex); 1997 info->vdevice = vdevice; 1998 info->connected = BLKIF_STATE_DISCONNECTED; 1999 2000 info->feature_persistent = feature_persistent; 2001 2002 /* Front end dir is a number, which is used as the id. */ 2003 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 2004 dev_set_drvdata(&dev->dev, info); 2005 2006 mutex_lock(&blkfront_mutex); 2007 list_add(&info->info_list, &info_list); 2008 mutex_unlock(&blkfront_mutex); 2009 2010 return 0; 2011 } 2012 2013 static int blkif_recover(struct blkfront_info *info) 2014 { 2015 unsigned int r_index; 2016 struct request *req, *n; 2017 int rc; 2018 struct bio *bio; 2019 unsigned int segs; 2020 struct blkfront_ring_info *rinfo; 2021 2022 blkfront_gather_backend_features(info); 2023 /* Reset limits changed by blk_mq_update_nr_hw_queues(). */ 2024 blkif_set_queue_limits(info); 2025 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 2026 blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG); 2027 2028 for_each_rinfo(info, rinfo, r_index) { 2029 rc = blkfront_setup_indirect(rinfo); 2030 if (rc) 2031 return rc; 2032 } 2033 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2034 2035 /* Now safe for us to use the shared ring */ 2036 info->connected = BLKIF_STATE_CONNECTED; 2037 2038 for_each_rinfo(info, rinfo, r_index) { 2039 /* Kick any other new requests queued since we resumed */ 2040 kick_pending_request_queues(rinfo); 2041 } 2042 2043 list_for_each_entry_safe(req, n, &info->requests, queuelist) { 2044 /* Requeue pending requests (flush or discard) */ 2045 list_del_init(&req->queuelist); 2046 BUG_ON(req->nr_phys_segments > segs); 2047 blk_mq_requeue_request(req, false); 2048 } 2049 blk_mq_start_stopped_hw_queues(info->rq, true); 2050 blk_mq_kick_requeue_list(info->rq); 2051 2052 while ((bio = bio_list_pop(&info->bio_list)) != NULL) { 2053 /* Traverse the list of pending bios and re-queue them */ 2054 submit_bio(bio); 2055 } 2056 2057 return 0; 2058 } 2059 2060 /* 2061 * We are reconnecting to the backend, due to a suspend/resume, or a backend 2062 * driver restart. We tear down our blkif structure and recreate it, but 2063 * leave the device-layer structures intact so that this is transparent to the 2064 * rest of the kernel. 2065 */ 2066 static int blkfront_resume(struct xenbus_device *dev) 2067 { 2068 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2069 int err = 0; 2070 unsigned int i, j; 2071 struct blkfront_ring_info *rinfo; 2072 2073 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 2074 2075 bio_list_init(&info->bio_list); 2076 INIT_LIST_HEAD(&info->requests); 2077 for_each_rinfo(info, rinfo, i) { 2078 struct bio_list merge_bio; 2079 struct blk_shadow *shadow = rinfo->shadow; 2080 2081 for (j = 0; j < BLK_RING_SIZE(info); j++) { 2082 /* Not in use? */ 2083 if (!shadow[j].request) 2084 continue; 2085 2086 /* 2087 * Get the bios in the request so we can re-queue them. 2088 */ 2089 if (req_op(shadow[j].request) == REQ_OP_FLUSH || 2090 req_op(shadow[j].request) == REQ_OP_DISCARD || 2091 req_op(shadow[j].request) == REQ_OP_SECURE_ERASE || 2092 shadow[j].request->cmd_flags & REQ_FUA) { 2093 /* 2094 * Flush operations don't contain bios, so 2095 * we need to requeue the whole request 2096 * 2097 * XXX: but this doesn't make any sense for a 2098 * write with the FUA flag set.. 2099 */ 2100 list_add(&shadow[j].request->queuelist, &info->requests); 2101 continue; 2102 } 2103 merge_bio.head = shadow[j].request->bio; 2104 merge_bio.tail = shadow[j].request->biotail; 2105 bio_list_merge(&info->bio_list, &merge_bio); 2106 shadow[j].request->bio = NULL; 2107 blk_mq_end_request(shadow[j].request, BLK_STS_OK); 2108 } 2109 } 2110 2111 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 2112 2113 err = talk_to_blkback(dev, info); 2114 if (!err) 2115 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings); 2116 2117 /* 2118 * We have to wait for the backend to switch to 2119 * connected state, since we want to read which 2120 * features it supports. 2121 */ 2122 2123 return err; 2124 } 2125 2126 static void blkfront_closing(struct blkfront_info *info) 2127 { 2128 struct xenbus_device *xbdev = info->xbdev; 2129 struct block_device *bdev = NULL; 2130 2131 mutex_lock(&info->mutex); 2132 2133 if (xbdev->state == XenbusStateClosing) { 2134 mutex_unlock(&info->mutex); 2135 return; 2136 } 2137 2138 if (info->gd) 2139 bdev = bdgrab(info->gd->part0); 2140 2141 mutex_unlock(&info->mutex); 2142 2143 if (!bdev) { 2144 xenbus_frontend_closed(xbdev); 2145 return; 2146 } 2147 2148 mutex_lock(&bdev->bd_disk->open_mutex); 2149 2150 if (bdev->bd_openers) { 2151 xenbus_dev_error(xbdev, -EBUSY, 2152 "Device in use; refusing to close"); 2153 xenbus_switch_state(xbdev, XenbusStateClosing); 2154 } else { 2155 xlvbd_release_gendisk(info); 2156 xenbus_frontend_closed(xbdev); 2157 } 2158 2159 mutex_unlock(&bdev->bd_disk->open_mutex); 2160 bdput(bdev); 2161 } 2162 2163 static void blkfront_setup_discard(struct blkfront_info *info) 2164 { 2165 info->feature_discard = 1; 2166 info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend, 2167 "discard-granularity", 2168 0); 2169 info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend, 2170 "discard-alignment", 0); 2171 info->feature_secdiscard = 2172 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure", 2173 0); 2174 } 2175 2176 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo) 2177 { 2178 unsigned int psegs, grants, memflags; 2179 int err, i; 2180 struct blkfront_info *info = rinfo->dev_info; 2181 2182 memflags = memalloc_noio_save(); 2183 2184 if (info->max_indirect_segments == 0) { 2185 if (!HAS_EXTRA_REQ) 2186 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2187 else { 2188 /* 2189 * When an extra req is required, the maximum 2190 * grants supported is related to the size of the 2191 * Linux block segment. 2192 */ 2193 grants = GRANTS_PER_PSEG; 2194 } 2195 } 2196 else 2197 grants = info->max_indirect_segments; 2198 psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG); 2199 2200 err = fill_grant_buffer(rinfo, 2201 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info)); 2202 if (err) 2203 goto out_of_memory; 2204 2205 if (!info->feature_persistent && info->max_indirect_segments) { 2206 /* 2207 * We are using indirect descriptors but not persistent 2208 * grants, we need to allocate a set of pages that can be 2209 * used for mapping indirect grefs 2210 */ 2211 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info); 2212 2213 BUG_ON(!list_empty(&rinfo->indirect_pages)); 2214 for (i = 0; i < num; i++) { 2215 struct page *indirect_page = alloc_page(GFP_KERNEL); 2216 if (!indirect_page) 2217 goto out_of_memory; 2218 list_add(&indirect_page->lru, &rinfo->indirect_pages); 2219 } 2220 } 2221 2222 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2223 rinfo->shadow[i].grants_used = 2224 kvcalloc(grants, 2225 sizeof(rinfo->shadow[i].grants_used[0]), 2226 GFP_KERNEL); 2227 rinfo->shadow[i].sg = kvcalloc(psegs, 2228 sizeof(rinfo->shadow[i].sg[0]), 2229 GFP_KERNEL); 2230 if (info->max_indirect_segments) 2231 rinfo->shadow[i].indirect_grants = 2232 kvcalloc(INDIRECT_GREFS(grants), 2233 sizeof(rinfo->shadow[i].indirect_grants[0]), 2234 GFP_KERNEL); 2235 if ((rinfo->shadow[i].grants_used == NULL) || 2236 (rinfo->shadow[i].sg == NULL) || 2237 (info->max_indirect_segments && 2238 (rinfo->shadow[i].indirect_grants == NULL))) 2239 goto out_of_memory; 2240 sg_init_table(rinfo->shadow[i].sg, psegs); 2241 } 2242 2243 memalloc_noio_restore(memflags); 2244 2245 return 0; 2246 2247 out_of_memory: 2248 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2249 kvfree(rinfo->shadow[i].grants_used); 2250 rinfo->shadow[i].grants_used = NULL; 2251 kvfree(rinfo->shadow[i].sg); 2252 rinfo->shadow[i].sg = NULL; 2253 kvfree(rinfo->shadow[i].indirect_grants); 2254 rinfo->shadow[i].indirect_grants = NULL; 2255 } 2256 if (!list_empty(&rinfo->indirect_pages)) { 2257 struct page *indirect_page, *n; 2258 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 2259 list_del(&indirect_page->lru); 2260 __free_page(indirect_page); 2261 } 2262 } 2263 2264 memalloc_noio_restore(memflags); 2265 2266 return -ENOMEM; 2267 } 2268 2269 /* 2270 * Gather all backend feature-* 2271 */ 2272 static void blkfront_gather_backend_features(struct blkfront_info *info) 2273 { 2274 unsigned int indirect_segments; 2275 2276 info->feature_flush = 0; 2277 info->feature_fua = 0; 2278 2279 /* 2280 * If there's no "feature-barrier" defined, then it means 2281 * we're dealing with a very old backend which writes 2282 * synchronously; nothing to do. 2283 * 2284 * If there are barriers, then we use flush. 2285 */ 2286 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) { 2287 info->feature_flush = 1; 2288 info->feature_fua = 1; 2289 } 2290 2291 /* 2292 * And if there is "feature-flush-cache" use that above 2293 * barriers. 2294 */ 2295 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache", 2296 0)) { 2297 info->feature_flush = 1; 2298 info->feature_fua = 0; 2299 } 2300 2301 if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0)) 2302 blkfront_setup_discard(info); 2303 2304 if (info->feature_persistent) 2305 info->feature_persistent = 2306 !!xenbus_read_unsigned(info->xbdev->otherend, 2307 "feature-persistent", 0); 2308 2309 indirect_segments = xenbus_read_unsigned(info->xbdev->otherend, 2310 "feature-max-indirect-segments", 0); 2311 if (indirect_segments > xen_blkif_max_segments) 2312 indirect_segments = xen_blkif_max_segments; 2313 if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST) 2314 indirect_segments = 0; 2315 info->max_indirect_segments = indirect_segments; 2316 2317 if (info->feature_persistent) { 2318 mutex_lock(&blkfront_mutex); 2319 schedule_delayed_work(&blkfront_work, HZ * 10); 2320 mutex_unlock(&blkfront_mutex); 2321 } 2322 } 2323 2324 /* 2325 * Invoked when the backend is finally 'ready' (and has told produced 2326 * the details about the physical device - #sectors, size, etc). 2327 */ 2328 static void blkfront_connect(struct blkfront_info *info) 2329 { 2330 unsigned long long sectors; 2331 unsigned long sector_size; 2332 unsigned int physical_sector_size; 2333 unsigned int binfo; 2334 int err, i; 2335 struct blkfront_ring_info *rinfo; 2336 2337 switch (info->connected) { 2338 case BLKIF_STATE_CONNECTED: 2339 /* 2340 * Potentially, the back-end may be signalling 2341 * a capacity change; update the capacity. 2342 */ 2343 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2344 "sectors", "%Lu", §ors); 2345 if (XENBUS_EXIST_ERR(err)) 2346 return; 2347 printk(KERN_INFO "Setting capacity to %Lu\n", 2348 sectors); 2349 set_capacity_and_notify(info->gd, sectors); 2350 2351 return; 2352 case BLKIF_STATE_SUSPENDED: 2353 /* 2354 * If we are recovering from suspension, we need to wait 2355 * for the backend to announce it's features before 2356 * reconnecting, at least we need to know if the backend 2357 * supports indirect descriptors, and how many. 2358 */ 2359 blkif_recover(info); 2360 return; 2361 2362 default: 2363 break; 2364 } 2365 2366 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 2367 __func__, info->xbdev->otherend); 2368 2369 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2370 "sectors", "%llu", §ors, 2371 "info", "%u", &binfo, 2372 "sector-size", "%lu", §or_size, 2373 NULL); 2374 if (err) { 2375 xenbus_dev_fatal(info->xbdev, err, 2376 "reading backend fields at %s", 2377 info->xbdev->otherend); 2378 return; 2379 } 2380 2381 /* 2382 * physical-sector-size is a newer field, so old backends may not 2383 * provide this. Assume physical sector size to be the same as 2384 * sector_size in that case. 2385 */ 2386 physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend, 2387 "physical-sector-size", 2388 sector_size); 2389 blkfront_gather_backend_features(info); 2390 for_each_rinfo(info, rinfo, i) { 2391 err = blkfront_setup_indirect(rinfo); 2392 if (err) { 2393 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 2394 info->xbdev->otherend); 2395 blkif_free(info, 0); 2396 break; 2397 } 2398 } 2399 2400 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 2401 physical_sector_size); 2402 if (err) { 2403 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 2404 info->xbdev->otherend); 2405 goto fail; 2406 } 2407 2408 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2409 2410 /* Kick pending requests. */ 2411 info->connected = BLKIF_STATE_CONNECTED; 2412 for_each_rinfo(info, rinfo, i) 2413 kick_pending_request_queues(rinfo); 2414 2415 device_add_disk(&info->xbdev->dev, info->gd, NULL); 2416 2417 info->is_ready = 1; 2418 return; 2419 2420 fail: 2421 blkif_free(info, 0); 2422 return; 2423 } 2424 2425 /* 2426 * Callback received when the backend's state changes. 2427 */ 2428 static void blkback_changed(struct xenbus_device *dev, 2429 enum xenbus_state backend_state) 2430 { 2431 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2432 2433 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 2434 2435 switch (backend_state) { 2436 case XenbusStateInitWait: 2437 if (dev->state != XenbusStateInitialising) 2438 break; 2439 if (talk_to_blkback(dev, info)) 2440 break; 2441 break; 2442 case XenbusStateInitialising: 2443 case XenbusStateInitialised: 2444 case XenbusStateReconfiguring: 2445 case XenbusStateReconfigured: 2446 case XenbusStateUnknown: 2447 break; 2448 2449 case XenbusStateConnected: 2450 /* 2451 * talk_to_blkback sets state to XenbusStateInitialised 2452 * and blkfront_connect sets it to XenbusStateConnected 2453 * (if connection went OK). 2454 * 2455 * If the backend (or toolstack) decides to poke at backend 2456 * state (and re-trigger the watch by setting the state repeatedly 2457 * to XenbusStateConnected (4)) we need to deal with this. 2458 * This is allowed as this is used to communicate to the guest 2459 * that the size of disk has changed! 2460 */ 2461 if ((dev->state != XenbusStateInitialised) && 2462 (dev->state != XenbusStateConnected)) { 2463 if (talk_to_blkback(dev, info)) 2464 break; 2465 } 2466 2467 blkfront_connect(info); 2468 break; 2469 2470 case XenbusStateClosed: 2471 if (dev->state == XenbusStateClosed) 2472 break; 2473 fallthrough; 2474 case XenbusStateClosing: 2475 if (info) 2476 blkfront_closing(info); 2477 break; 2478 } 2479 } 2480 2481 static int blkfront_remove(struct xenbus_device *xbdev) 2482 { 2483 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 2484 struct block_device *bdev = NULL; 2485 struct gendisk *disk; 2486 2487 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 2488 2489 if (!info) 2490 return 0; 2491 2492 blkif_free(info, 0); 2493 2494 mutex_lock(&info->mutex); 2495 2496 disk = info->gd; 2497 if (disk) 2498 bdev = bdgrab(disk->part0); 2499 2500 info->xbdev = NULL; 2501 mutex_unlock(&info->mutex); 2502 2503 if (!bdev) { 2504 mutex_lock(&blkfront_mutex); 2505 free_info(info); 2506 mutex_unlock(&blkfront_mutex); 2507 return 0; 2508 } 2509 2510 /* 2511 * The xbdev was removed before we reached the Closed 2512 * state. See if it's safe to remove the disk. If the bdev 2513 * isn't closed yet, we let release take care of it. 2514 */ 2515 2516 mutex_lock(&disk->open_mutex); 2517 info = disk->private_data; 2518 2519 dev_warn(disk_to_dev(disk), 2520 "%s was hot-unplugged, %d stale handles\n", 2521 xbdev->nodename, bdev->bd_openers); 2522 2523 if (info && !bdev->bd_openers) { 2524 xlvbd_release_gendisk(info); 2525 disk->private_data = NULL; 2526 mutex_lock(&blkfront_mutex); 2527 free_info(info); 2528 mutex_unlock(&blkfront_mutex); 2529 } 2530 2531 mutex_unlock(&disk->open_mutex); 2532 bdput(bdev); 2533 2534 return 0; 2535 } 2536 2537 static int blkfront_is_ready(struct xenbus_device *dev) 2538 { 2539 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2540 2541 return info->is_ready && info->xbdev; 2542 } 2543 2544 static int blkif_open(struct block_device *bdev, fmode_t mode) 2545 { 2546 struct gendisk *disk = bdev->bd_disk; 2547 struct blkfront_info *info; 2548 int err = 0; 2549 2550 mutex_lock(&blkfront_mutex); 2551 2552 info = disk->private_data; 2553 if (!info) { 2554 /* xbdev gone */ 2555 err = -ERESTARTSYS; 2556 goto out; 2557 } 2558 2559 mutex_lock(&info->mutex); 2560 2561 if (!info->gd) 2562 /* xbdev is closed */ 2563 err = -ERESTARTSYS; 2564 2565 mutex_unlock(&info->mutex); 2566 2567 out: 2568 mutex_unlock(&blkfront_mutex); 2569 return err; 2570 } 2571 2572 static void blkif_release(struct gendisk *disk, fmode_t mode) 2573 { 2574 struct blkfront_info *info = disk->private_data; 2575 struct xenbus_device *xbdev; 2576 2577 mutex_lock(&blkfront_mutex); 2578 if (disk->part0->bd_openers) 2579 goto out_mutex; 2580 2581 /* 2582 * Check if we have been instructed to close. We will have 2583 * deferred this request, because the bdev was still open. 2584 */ 2585 2586 mutex_lock(&info->mutex); 2587 xbdev = info->xbdev; 2588 2589 if (xbdev && xbdev->state == XenbusStateClosing) { 2590 /* pending switch to state closed */ 2591 dev_info(disk_to_dev(disk), "releasing disk\n"); 2592 xlvbd_release_gendisk(info); 2593 xenbus_frontend_closed(info->xbdev); 2594 } 2595 2596 mutex_unlock(&info->mutex); 2597 2598 if (!xbdev) { 2599 /* sudden device removal */ 2600 dev_info(disk_to_dev(disk), "releasing disk\n"); 2601 xlvbd_release_gendisk(info); 2602 disk->private_data = NULL; 2603 free_info(info); 2604 } 2605 2606 out_mutex: 2607 mutex_unlock(&blkfront_mutex); 2608 } 2609 2610 static const struct block_device_operations xlvbd_block_fops = 2611 { 2612 .owner = THIS_MODULE, 2613 .open = blkif_open, 2614 .release = blkif_release, 2615 .getgeo = blkif_getgeo, 2616 .ioctl = blkif_ioctl, 2617 .compat_ioctl = blkdev_compat_ptr_ioctl, 2618 }; 2619 2620 2621 static const struct xenbus_device_id blkfront_ids[] = { 2622 { "vbd" }, 2623 { "" } 2624 }; 2625 2626 static struct xenbus_driver blkfront_driver = { 2627 .ids = blkfront_ids, 2628 .probe = blkfront_probe, 2629 .remove = blkfront_remove, 2630 .resume = blkfront_resume, 2631 .otherend_changed = blkback_changed, 2632 .is_ready = blkfront_is_ready, 2633 }; 2634 2635 static void purge_persistent_grants(struct blkfront_info *info) 2636 { 2637 unsigned int i; 2638 unsigned long flags; 2639 struct blkfront_ring_info *rinfo; 2640 2641 for_each_rinfo(info, rinfo, i) { 2642 struct grant *gnt_list_entry, *tmp; 2643 2644 spin_lock_irqsave(&rinfo->ring_lock, flags); 2645 2646 if (rinfo->persistent_gnts_c == 0) { 2647 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 2648 continue; 2649 } 2650 2651 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants, 2652 node) { 2653 if (gnt_list_entry->gref == GRANT_INVALID_REF || 2654 gnttab_query_foreign_access(gnt_list_entry->gref)) 2655 continue; 2656 2657 list_del(&gnt_list_entry->node); 2658 gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL); 2659 rinfo->persistent_gnts_c--; 2660 gnt_list_entry->gref = GRANT_INVALID_REF; 2661 list_add_tail(&gnt_list_entry->node, &rinfo->grants); 2662 } 2663 2664 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 2665 } 2666 } 2667 2668 static void blkfront_delay_work(struct work_struct *work) 2669 { 2670 struct blkfront_info *info; 2671 bool need_schedule_work = false; 2672 2673 mutex_lock(&blkfront_mutex); 2674 2675 list_for_each_entry(info, &info_list, info_list) { 2676 if (info->feature_persistent) { 2677 need_schedule_work = true; 2678 mutex_lock(&info->mutex); 2679 purge_persistent_grants(info); 2680 mutex_unlock(&info->mutex); 2681 } 2682 } 2683 2684 if (need_schedule_work) 2685 schedule_delayed_work(&blkfront_work, HZ * 10); 2686 2687 mutex_unlock(&blkfront_mutex); 2688 } 2689 2690 static int __init xlblk_init(void) 2691 { 2692 int ret; 2693 int nr_cpus = num_online_cpus(); 2694 2695 if (!xen_domain()) 2696 return -ENODEV; 2697 2698 if (!xen_has_pv_disk_devices()) 2699 return -ENODEV; 2700 2701 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2702 pr_warn("xen_blk: can't get major %d with name %s\n", 2703 XENVBD_MAJOR, DEV_NAME); 2704 return -ENODEV; 2705 } 2706 2707 if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST) 2708 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2709 2710 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { 2711 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 2712 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); 2713 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 2714 } 2715 2716 if (xen_blkif_max_queues > nr_cpus) { 2717 pr_info("Invalid max_queues (%d), will use default max: %d.\n", 2718 xen_blkif_max_queues, nr_cpus); 2719 xen_blkif_max_queues = nr_cpus; 2720 } 2721 2722 INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work); 2723 2724 ret = xenbus_register_frontend(&blkfront_driver); 2725 if (ret) { 2726 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2727 return ret; 2728 } 2729 2730 return 0; 2731 } 2732 module_init(xlblk_init); 2733 2734 2735 static void __exit xlblk_exit(void) 2736 { 2737 cancel_delayed_work_sync(&blkfront_work); 2738 2739 xenbus_unregister_driver(&blkfront_driver); 2740 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2741 kfree(minors); 2742 } 2743 module_exit(xlblk_exit); 2744 2745 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2746 MODULE_LICENSE("GPL"); 2747 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2748 MODULE_ALIAS("xen:vbd"); 2749 MODULE_ALIAS("xenblk"); 2750