1 /* 2 * blkfront.c 3 * 4 * XenLinux virtual block device driver. 5 * 6 * Copyright (c) 2003-2004, Keir Fraser & Steve Hand 7 * Modifications by Mark A. Williamson are (c) Intel Research Cambridge 8 * Copyright (c) 2004, Christian Limpach 9 * Copyright (c) 2004, Andrew Warfield 10 * Copyright (c) 2005, Christopher Clark 11 * Copyright (c) 2005, XenSource Ltd 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License version 2 15 * as published by the Free Software Foundation; or, when distributed 16 * separately from the Linux kernel or incorporated into other 17 * software packages, subject to the following license: 18 * 19 * Permission is hereby granted, free of charge, to any person obtaining a copy 20 * of this source file (the "Software"), to deal in the Software without 21 * restriction, including without limitation the rights to use, copy, modify, 22 * merge, publish, distribute, sublicense, and/or sell copies of the Software, 23 * and to permit persons to whom the Software is furnished to do so, subject to 24 * the following conditions: 25 * 26 * The above copyright notice and this permission notice shall be included in 27 * all copies or substantial portions of the Software. 28 * 29 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 30 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 31 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 32 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 33 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 34 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 35 * IN THE SOFTWARE. 36 */ 37 38 #include <linux/interrupt.h> 39 #include <linux/blkdev.h> 40 #include <linux/blk-mq.h> 41 #include <linux/hdreg.h> 42 #include <linux/cdrom.h> 43 #include <linux/module.h> 44 #include <linux/slab.h> 45 #include <linux/mutex.h> 46 #include <linux/scatterlist.h> 47 #include <linux/bitmap.h> 48 #include <linux/list.h> 49 50 #include <xen/xen.h> 51 #include <xen/xenbus.h> 52 #include <xen/grant_table.h> 53 #include <xen/events.h> 54 #include <xen/page.h> 55 #include <xen/platform_pci.h> 56 57 #include <xen/interface/grant_table.h> 58 #include <xen/interface/io/blkif.h> 59 #include <xen/interface/io/protocols.h> 60 61 #include <asm/xen/hypervisor.h> 62 63 /* 64 * The minimal size of segment supported by the block framework is PAGE_SIZE. 65 * When Linux is using a different page size than Xen, it may not be possible 66 * to put all the data in a single segment. 67 * This can happen when the backend doesn't support indirect descriptor and 68 * therefore the maximum amount of data that a request can carry is 69 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB 70 * 71 * Note that we only support one extra request. So the Linux page size 72 * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) = 73 * 88KB. 74 */ 75 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE) 76 77 enum blkif_state { 78 BLKIF_STATE_DISCONNECTED, 79 BLKIF_STATE_CONNECTED, 80 BLKIF_STATE_SUSPENDED, 81 }; 82 83 struct grant { 84 grant_ref_t gref; 85 struct page *page; 86 struct list_head node; 87 }; 88 89 enum blk_req_status { 90 REQ_WAITING, 91 REQ_DONE, 92 REQ_ERROR, 93 REQ_EOPNOTSUPP, 94 }; 95 96 struct blk_shadow { 97 struct blkif_request req; 98 struct request *request; 99 struct grant **grants_used; 100 struct grant **indirect_grants; 101 struct scatterlist *sg; 102 unsigned int num_sg; 103 enum blk_req_status status; 104 105 #define NO_ASSOCIATED_ID ~0UL 106 /* 107 * Id of the sibling if we ever need 2 requests when handling a 108 * block I/O request 109 */ 110 unsigned long associated_id; 111 }; 112 113 struct split_bio { 114 struct bio *bio; 115 atomic_t pending; 116 }; 117 118 static DEFINE_MUTEX(blkfront_mutex); 119 static const struct block_device_operations xlvbd_block_fops; 120 121 /* 122 * Maximum number of segments in indirect requests, the actual value used by 123 * the frontend driver is the minimum of this value and the value provided 124 * by the backend driver. 125 */ 126 127 static unsigned int xen_blkif_max_segments = 32; 128 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 129 S_IRUGO); 130 MODULE_PARM_DESC(max_indirect_segments, 131 "Maximum amount of segments in indirect requests (default is 32)"); 132 133 static unsigned int xen_blkif_max_queues = 4; 134 module_param_named(max_queues, xen_blkif_max_queues, uint, S_IRUGO); 135 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk"); 136 137 /* 138 * Maximum order of pages to be used for the shared ring between front and 139 * backend, 4KB page granularity is used. 140 */ 141 static unsigned int xen_blkif_max_ring_order; 142 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO); 143 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 144 145 #define BLK_RING_SIZE(info) \ 146 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages) 147 148 #define BLK_MAX_RING_SIZE \ 149 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS) 150 151 /* 152 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 153 * characters are enough. Define to 20 to keep consistent with backend. 154 */ 155 #define RINGREF_NAME_LEN (20) 156 /* 157 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters. 158 */ 159 #define QUEUE_NAME_LEN (17) 160 161 /* 162 * Per-ring info. 163 * Every blkfront device can associate with one or more blkfront_ring_info, 164 * depending on how many hardware queues/rings to be used. 165 */ 166 struct blkfront_ring_info { 167 /* Lock to protect data in every ring buffer. */ 168 spinlock_t ring_lock; 169 struct blkif_front_ring ring; 170 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS]; 171 unsigned int evtchn, irq; 172 struct work_struct work; 173 struct gnttab_free_callback callback; 174 struct blk_shadow shadow[BLK_MAX_RING_SIZE]; 175 struct list_head indirect_pages; 176 struct list_head grants; 177 unsigned int persistent_gnts_c; 178 unsigned long shadow_free; 179 struct blkfront_info *dev_info; 180 }; 181 182 /* 183 * We have one of these per vbd, whether ide, scsi or 'other'. They 184 * hang in private_data off the gendisk structure. We may end up 185 * putting all kinds of interesting stuff here :-) 186 */ 187 struct blkfront_info 188 { 189 struct mutex mutex; 190 struct xenbus_device *xbdev; 191 struct gendisk *gd; 192 int vdevice; 193 blkif_vdev_t handle; 194 enum blkif_state connected; 195 /* Number of pages per ring buffer. */ 196 unsigned int nr_ring_pages; 197 struct request_queue *rq; 198 unsigned int feature_flush; 199 unsigned int feature_fua; 200 unsigned int feature_discard:1; 201 unsigned int feature_secdiscard:1; 202 unsigned int discard_granularity; 203 unsigned int discard_alignment; 204 unsigned int feature_persistent:1; 205 /* Number of 4KB segments handled */ 206 unsigned int max_indirect_segments; 207 int is_ready; 208 struct blk_mq_tag_set tag_set; 209 struct blkfront_ring_info *rinfo; 210 unsigned int nr_rings; 211 /* Save uncomplete reqs and bios for migration. */ 212 struct list_head requests; 213 struct bio_list bio_list; 214 }; 215 216 static unsigned int nr_minors; 217 static unsigned long *minors; 218 static DEFINE_SPINLOCK(minor_lock); 219 220 #define GRANT_INVALID_REF 0 221 222 #define PARTS_PER_DISK 16 223 #define PARTS_PER_EXT_DISK 256 224 225 #define BLKIF_MAJOR(dev) ((dev)>>8) 226 #define BLKIF_MINOR(dev) ((dev) & 0xff) 227 228 #define EXT_SHIFT 28 229 #define EXTENDED (1<<EXT_SHIFT) 230 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 231 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 232 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 233 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 234 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 235 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 236 237 #define DEV_NAME "xvd" /* name in /dev */ 238 239 /* 240 * Grants are always the same size as a Xen page (i.e 4KB). 241 * A physical segment is always the same size as a Linux page. 242 * Number of grants per physical segment 243 */ 244 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE) 245 246 #define GRANTS_PER_INDIRECT_FRAME \ 247 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment)) 248 249 #define PSEGS_PER_INDIRECT_FRAME \ 250 (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS) 251 252 #define INDIRECT_GREFS(_grants) \ 253 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME) 254 255 #define GREFS(_psegs) ((_psegs) * GRANTS_PER_PSEG) 256 257 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo); 258 static void blkfront_gather_backend_features(struct blkfront_info *info); 259 260 static int get_id_from_freelist(struct blkfront_ring_info *rinfo) 261 { 262 unsigned long free = rinfo->shadow_free; 263 264 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info)); 265 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id; 266 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 267 return free; 268 } 269 270 static int add_id_to_freelist(struct blkfront_ring_info *rinfo, 271 unsigned long id) 272 { 273 if (rinfo->shadow[id].req.u.rw.id != id) 274 return -EINVAL; 275 if (rinfo->shadow[id].request == NULL) 276 return -EINVAL; 277 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free; 278 rinfo->shadow[id].request = NULL; 279 rinfo->shadow_free = id; 280 return 0; 281 } 282 283 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 284 { 285 struct blkfront_info *info = rinfo->dev_info; 286 struct page *granted_page; 287 struct grant *gnt_list_entry, *n; 288 int i = 0; 289 290 while (i < num) { 291 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 292 if (!gnt_list_entry) 293 goto out_of_memory; 294 295 if (info->feature_persistent) { 296 granted_page = alloc_page(GFP_NOIO); 297 if (!granted_page) { 298 kfree(gnt_list_entry); 299 goto out_of_memory; 300 } 301 gnt_list_entry->page = granted_page; 302 } 303 304 gnt_list_entry->gref = GRANT_INVALID_REF; 305 list_add(&gnt_list_entry->node, &rinfo->grants); 306 i++; 307 } 308 309 return 0; 310 311 out_of_memory: 312 list_for_each_entry_safe(gnt_list_entry, n, 313 &rinfo->grants, node) { 314 list_del(&gnt_list_entry->node); 315 if (info->feature_persistent) 316 __free_page(gnt_list_entry->page); 317 kfree(gnt_list_entry); 318 i--; 319 } 320 BUG_ON(i != 0); 321 return -ENOMEM; 322 } 323 324 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo) 325 { 326 struct grant *gnt_list_entry; 327 328 BUG_ON(list_empty(&rinfo->grants)); 329 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant, 330 node); 331 list_del(&gnt_list_entry->node); 332 333 if (gnt_list_entry->gref != GRANT_INVALID_REF) 334 rinfo->persistent_gnts_c--; 335 336 return gnt_list_entry; 337 } 338 339 static inline void grant_foreign_access(const struct grant *gnt_list_entry, 340 const struct blkfront_info *info) 341 { 342 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref, 343 info->xbdev->otherend_id, 344 gnt_list_entry->page, 345 0); 346 } 347 348 static struct grant *get_grant(grant_ref_t *gref_head, 349 unsigned long gfn, 350 struct blkfront_ring_info *rinfo) 351 { 352 struct grant *gnt_list_entry = get_free_grant(rinfo); 353 struct blkfront_info *info = rinfo->dev_info; 354 355 if (gnt_list_entry->gref != GRANT_INVALID_REF) 356 return gnt_list_entry; 357 358 /* Assign a gref to this page */ 359 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 360 BUG_ON(gnt_list_entry->gref == -ENOSPC); 361 if (info->feature_persistent) 362 grant_foreign_access(gnt_list_entry, info); 363 else { 364 /* Grant access to the GFN passed by the caller */ 365 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 366 info->xbdev->otherend_id, 367 gfn, 0); 368 } 369 370 return gnt_list_entry; 371 } 372 373 static struct grant *get_indirect_grant(grant_ref_t *gref_head, 374 struct blkfront_ring_info *rinfo) 375 { 376 struct grant *gnt_list_entry = get_free_grant(rinfo); 377 struct blkfront_info *info = rinfo->dev_info; 378 379 if (gnt_list_entry->gref != GRANT_INVALID_REF) 380 return gnt_list_entry; 381 382 /* Assign a gref to this page */ 383 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 384 BUG_ON(gnt_list_entry->gref == -ENOSPC); 385 if (!info->feature_persistent) { 386 struct page *indirect_page; 387 388 /* Fetch a pre-allocated page to use for indirect grefs */ 389 BUG_ON(list_empty(&rinfo->indirect_pages)); 390 indirect_page = list_first_entry(&rinfo->indirect_pages, 391 struct page, lru); 392 list_del(&indirect_page->lru); 393 gnt_list_entry->page = indirect_page; 394 } 395 grant_foreign_access(gnt_list_entry, info); 396 397 return gnt_list_entry; 398 } 399 400 static const char *op_name(int op) 401 { 402 static const char *const names[] = { 403 [BLKIF_OP_READ] = "read", 404 [BLKIF_OP_WRITE] = "write", 405 [BLKIF_OP_WRITE_BARRIER] = "barrier", 406 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 407 [BLKIF_OP_DISCARD] = "discard" }; 408 409 if (op < 0 || op >= ARRAY_SIZE(names)) 410 return "unknown"; 411 412 if (!names[op]) 413 return "reserved"; 414 415 return names[op]; 416 } 417 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 418 { 419 unsigned int end = minor + nr; 420 int rc; 421 422 if (end > nr_minors) { 423 unsigned long *bitmap, *old; 424 425 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 426 GFP_KERNEL); 427 if (bitmap == NULL) 428 return -ENOMEM; 429 430 spin_lock(&minor_lock); 431 if (end > nr_minors) { 432 old = minors; 433 memcpy(bitmap, minors, 434 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 435 minors = bitmap; 436 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 437 } else 438 old = bitmap; 439 spin_unlock(&minor_lock); 440 kfree(old); 441 } 442 443 spin_lock(&minor_lock); 444 if (find_next_bit(minors, end, minor) >= end) { 445 bitmap_set(minors, minor, nr); 446 rc = 0; 447 } else 448 rc = -EBUSY; 449 spin_unlock(&minor_lock); 450 451 return rc; 452 } 453 454 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 455 { 456 unsigned int end = minor + nr; 457 458 BUG_ON(end > nr_minors); 459 spin_lock(&minor_lock); 460 bitmap_clear(minors, minor, nr); 461 spin_unlock(&minor_lock); 462 } 463 464 static void blkif_restart_queue_callback(void *arg) 465 { 466 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg; 467 schedule_work(&rinfo->work); 468 } 469 470 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 471 { 472 /* We don't have real geometry info, but let's at least return 473 values consistent with the size of the device */ 474 sector_t nsect = get_capacity(bd->bd_disk); 475 sector_t cylinders = nsect; 476 477 hg->heads = 0xff; 478 hg->sectors = 0x3f; 479 sector_div(cylinders, hg->heads * hg->sectors); 480 hg->cylinders = cylinders; 481 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 482 hg->cylinders = 0xffff; 483 return 0; 484 } 485 486 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 487 unsigned command, unsigned long argument) 488 { 489 struct blkfront_info *info = bdev->bd_disk->private_data; 490 int i; 491 492 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 493 command, (long)argument); 494 495 switch (command) { 496 case CDROMMULTISESSION: 497 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 498 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 499 if (put_user(0, (char __user *)(argument + i))) 500 return -EFAULT; 501 return 0; 502 503 case CDROM_GET_CAPABILITY: { 504 struct gendisk *gd = info->gd; 505 if (gd->flags & GENHD_FL_CD) 506 return 0; 507 return -EINVAL; 508 } 509 510 default: 511 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 512 command);*/ 513 return -EINVAL; /* same return as native Linux */ 514 } 515 516 return 0; 517 } 518 519 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, 520 struct request *req, 521 struct blkif_request **ring_req) 522 { 523 unsigned long id; 524 525 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt); 526 rinfo->ring.req_prod_pvt++; 527 528 id = get_id_from_freelist(rinfo); 529 rinfo->shadow[id].request = req; 530 rinfo->shadow[id].status = REQ_WAITING; 531 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID; 532 533 (*ring_req)->u.rw.id = id; 534 535 return id; 536 } 537 538 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo) 539 { 540 struct blkfront_info *info = rinfo->dev_info; 541 struct blkif_request *ring_req; 542 unsigned long id; 543 544 /* Fill out a communications ring structure. */ 545 id = blkif_ring_get_request(rinfo, req, &ring_req); 546 547 ring_req->operation = BLKIF_OP_DISCARD; 548 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 549 ring_req->u.discard.id = id; 550 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 551 if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard) 552 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 553 else 554 ring_req->u.discard.flag = 0; 555 556 /* Keep a private copy so we can reissue requests when recovering. */ 557 rinfo->shadow[id].req = *ring_req; 558 559 return 0; 560 } 561 562 struct setup_rw_req { 563 unsigned int grant_idx; 564 struct blkif_request_segment *segments; 565 struct blkfront_ring_info *rinfo; 566 struct blkif_request *ring_req; 567 grant_ref_t gref_head; 568 unsigned int id; 569 /* Only used when persistent grant is used and it's a read request */ 570 bool need_copy; 571 unsigned int bvec_off; 572 char *bvec_data; 573 574 bool require_extra_req; 575 struct blkif_request *extra_ring_req; 576 }; 577 578 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset, 579 unsigned int len, void *data) 580 { 581 struct setup_rw_req *setup = data; 582 int n, ref; 583 struct grant *gnt_list_entry; 584 unsigned int fsect, lsect; 585 /* Convenient aliases */ 586 unsigned int grant_idx = setup->grant_idx; 587 struct blkif_request *ring_req = setup->ring_req; 588 struct blkfront_ring_info *rinfo = setup->rinfo; 589 /* 590 * We always use the shadow of the first request to store the list 591 * of grant associated to the block I/O request. This made the 592 * completion more easy to handle even if the block I/O request is 593 * split. 594 */ 595 struct blk_shadow *shadow = &rinfo->shadow[setup->id]; 596 597 if (unlikely(setup->require_extra_req && 598 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 599 /* 600 * We are using the second request, setup grant_idx 601 * to be the index of the segment array. 602 */ 603 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST; 604 ring_req = setup->extra_ring_req; 605 } 606 607 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 608 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) { 609 if (setup->segments) 610 kunmap_atomic(setup->segments); 611 612 n = grant_idx / GRANTS_PER_INDIRECT_FRAME; 613 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo); 614 shadow->indirect_grants[n] = gnt_list_entry; 615 setup->segments = kmap_atomic(gnt_list_entry->page); 616 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 617 } 618 619 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo); 620 ref = gnt_list_entry->gref; 621 /* 622 * All the grants are stored in the shadow of the first 623 * request. Therefore we have to use the global index. 624 */ 625 shadow->grants_used[setup->grant_idx] = gnt_list_entry; 626 627 if (setup->need_copy) { 628 void *shared_data; 629 630 shared_data = kmap_atomic(gnt_list_entry->page); 631 /* 632 * this does not wipe data stored outside the 633 * range sg->offset..sg->offset+sg->length. 634 * Therefore, blkback *could* see data from 635 * previous requests. This is OK as long as 636 * persistent grants are shared with just one 637 * domain. It may need refactoring if this 638 * changes 639 */ 640 memcpy(shared_data + offset, 641 setup->bvec_data + setup->bvec_off, 642 len); 643 644 kunmap_atomic(shared_data); 645 setup->bvec_off += len; 646 } 647 648 fsect = offset >> 9; 649 lsect = fsect + (len >> 9) - 1; 650 if (ring_req->operation != BLKIF_OP_INDIRECT) { 651 ring_req->u.rw.seg[grant_idx] = 652 (struct blkif_request_segment) { 653 .gref = ref, 654 .first_sect = fsect, 655 .last_sect = lsect }; 656 } else { 657 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] = 658 (struct blkif_request_segment) { 659 .gref = ref, 660 .first_sect = fsect, 661 .last_sect = lsect }; 662 } 663 664 (setup->grant_idx)++; 665 } 666 667 static void blkif_setup_extra_req(struct blkif_request *first, 668 struct blkif_request *second) 669 { 670 uint16_t nr_segments = first->u.rw.nr_segments; 671 672 /* 673 * The second request is only present when the first request uses 674 * all its segments. It's always the continuity of the first one. 675 */ 676 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 677 678 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST; 679 second->u.rw.sector_number = first->u.rw.sector_number + 680 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512; 681 682 second->u.rw.handle = first->u.rw.handle; 683 second->operation = first->operation; 684 } 685 686 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo) 687 { 688 struct blkfront_info *info = rinfo->dev_info; 689 struct blkif_request *ring_req, *extra_ring_req = NULL; 690 unsigned long id, extra_id = NO_ASSOCIATED_ID; 691 bool require_extra_req = false; 692 int i; 693 struct setup_rw_req setup = { 694 .grant_idx = 0, 695 .segments = NULL, 696 .rinfo = rinfo, 697 .need_copy = rq_data_dir(req) && info->feature_persistent, 698 }; 699 700 /* 701 * Used to store if we are able to queue the request by just using 702 * existing persistent grants, or if we have to get new grants, 703 * as there are not sufficiently many free. 704 */ 705 struct scatterlist *sg; 706 int num_sg, max_grefs, num_grant; 707 708 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG; 709 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 710 /* 711 * If we are using indirect segments we need to account 712 * for the indirect grefs used in the request. 713 */ 714 max_grefs += INDIRECT_GREFS(max_grefs); 715 716 /* 717 * We have to reserve 'max_grefs' grants because persistent 718 * grants are shared by all rings. 719 */ 720 if (max_grefs > 0) 721 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) { 722 gnttab_request_free_callback( 723 &rinfo->callback, 724 blkif_restart_queue_callback, 725 rinfo, 726 max_grefs); 727 return 1; 728 } 729 730 /* Fill out a communications ring structure. */ 731 id = blkif_ring_get_request(rinfo, req, &ring_req); 732 733 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg); 734 num_grant = 0; 735 /* Calculate the number of grant used */ 736 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) 737 num_grant += gnttab_count_grant(sg->offset, sg->length); 738 739 require_extra_req = info->max_indirect_segments == 0 && 740 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST; 741 BUG_ON(!HAS_EXTRA_REQ && require_extra_req); 742 743 rinfo->shadow[id].num_sg = num_sg; 744 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST && 745 likely(!require_extra_req)) { 746 /* 747 * The indirect operation can only be a BLKIF_OP_READ or 748 * BLKIF_OP_WRITE 749 */ 750 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA); 751 ring_req->operation = BLKIF_OP_INDIRECT; 752 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 753 BLKIF_OP_WRITE : BLKIF_OP_READ; 754 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 755 ring_req->u.indirect.handle = info->handle; 756 ring_req->u.indirect.nr_segments = num_grant; 757 } else { 758 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 759 ring_req->u.rw.handle = info->handle; 760 ring_req->operation = rq_data_dir(req) ? 761 BLKIF_OP_WRITE : BLKIF_OP_READ; 762 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) { 763 /* 764 * Ideally we can do an unordered flush-to-disk. 765 * In case the backend onlysupports barriers, use that. 766 * A barrier request a superset of FUA, so we can 767 * implement it the same way. (It's also a FLUSH+FUA, 768 * since it is guaranteed ordered WRT previous writes.) 769 */ 770 if (info->feature_flush && info->feature_fua) 771 ring_req->operation = 772 BLKIF_OP_WRITE_BARRIER; 773 else if (info->feature_flush) 774 ring_req->operation = 775 BLKIF_OP_FLUSH_DISKCACHE; 776 else 777 ring_req->operation = 0; 778 } 779 ring_req->u.rw.nr_segments = num_grant; 780 if (unlikely(require_extra_req)) { 781 extra_id = blkif_ring_get_request(rinfo, req, 782 &extra_ring_req); 783 /* 784 * Only the first request contains the scatter-gather 785 * list. 786 */ 787 rinfo->shadow[extra_id].num_sg = 0; 788 789 blkif_setup_extra_req(ring_req, extra_ring_req); 790 791 /* Link the 2 requests together */ 792 rinfo->shadow[extra_id].associated_id = id; 793 rinfo->shadow[id].associated_id = extra_id; 794 } 795 } 796 797 setup.ring_req = ring_req; 798 setup.id = id; 799 800 setup.require_extra_req = require_extra_req; 801 if (unlikely(require_extra_req)) 802 setup.extra_ring_req = extra_ring_req; 803 804 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) { 805 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 806 807 if (setup.need_copy) { 808 setup.bvec_off = sg->offset; 809 setup.bvec_data = kmap_atomic(sg_page(sg)); 810 } 811 812 gnttab_foreach_grant_in_range(sg_page(sg), 813 sg->offset, 814 sg->length, 815 blkif_setup_rw_req_grant, 816 &setup); 817 818 if (setup.need_copy) 819 kunmap_atomic(setup.bvec_data); 820 } 821 if (setup.segments) 822 kunmap_atomic(setup.segments); 823 824 /* Keep a private copy so we can reissue requests when recovering. */ 825 rinfo->shadow[id].req = *ring_req; 826 if (unlikely(require_extra_req)) 827 rinfo->shadow[extra_id].req = *extra_ring_req; 828 829 if (max_grefs > 0) 830 gnttab_free_grant_references(setup.gref_head); 831 832 return 0; 833 } 834 835 /* 836 * Generate a Xen blkfront IO request from a blk layer request. Reads 837 * and writes are handled as expected. 838 * 839 * @req: a request struct 840 */ 841 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo) 842 { 843 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED)) 844 return 1; 845 846 if (unlikely(req_op(req) == REQ_OP_DISCARD || 847 req_op(req) == REQ_OP_SECURE_ERASE)) 848 return blkif_queue_discard_req(req, rinfo); 849 else 850 return blkif_queue_rw_req(req, rinfo); 851 } 852 853 static inline void flush_requests(struct blkfront_ring_info *rinfo) 854 { 855 int notify; 856 857 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify); 858 859 if (notify) 860 notify_remote_via_irq(rinfo->irq); 861 } 862 863 static inline bool blkif_request_flush_invalid(struct request *req, 864 struct blkfront_info *info) 865 { 866 return ((req->cmd_type != REQ_TYPE_FS) || 867 ((req_op(req) == REQ_OP_FLUSH) && 868 !info->feature_flush) || 869 ((req->cmd_flags & REQ_FUA) && 870 !info->feature_fua)); 871 } 872 873 static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx, 874 const struct blk_mq_queue_data *qd) 875 { 876 unsigned long flags; 877 int qid = hctx->queue_num; 878 struct blkfront_info *info = hctx->queue->queuedata; 879 struct blkfront_ring_info *rinfo = NULL; 880 881 BUG_ON(info->nr_rings <= qid); 882 rinfo = &info->rinfo[qid]; 883 blk_mq_start_request(qd->rq); 884 spin_lock_irqsave(&rinfo->ring_lock, flags); 885 if (RING_FULL(&rinfo->ring)) 886 goto out_busy; 887 888 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info)) 889 goto out_err; 890 891 if (blkif_queue_request(qd->rq, rinfo)) 892 goto out_busy; 893 894 flush_requests(rinfo); 895 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 896 return BLK_MQ_RQ_QUEUE_OK; 897 898 out_err: 899 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 900 return BLK_MQ_RQ_QUEUE_ERROR; 901 902 out_busy: 903 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 904 blk_mq_stop_hw_queue(hctx); 905 return BLK_MQ_RQ_QUEUE_BUSY; 906 } 907 908 static struct blk_mq_ops blkfront_mq_ops = { 909 .queue_rq = blkif_queue_rq, 910 .map_queue = blk_mq_map_queue, 911 }; 912 913 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, 914 unsigned int physical_sector_size, 915 unsigned int segments) 916 { 917 struct request_queue *rq; 918 struct blkfront_info *info = gd->private_data; 919 920 memset(&info->tag_set, 0, sizeof(info->tag_set)); 921 info->tag_set.ops = &blkfront_mq_ops; 922 info->tag_set.nr_hw_queues = info->nr_rings; 923 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) { 924 /* 925 * When indirect descriptior is not supported, the I/O request 926 * will be split between multiple request in the ring. 927 * To avoid problems when sending the request, divide by 928 * 2 the depth of the queue. 929 */ 930 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2; 931 } else 932 info->tag_set.queue_depth = BLK_RING_SIZE(info); 933 info->tag_set.numa_node = NUMA_NO_NODE; 934 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; 935 info->tag_set.cmd_size = 0; 936 info->tag_set.driver_data = info; 937 938 if (blk_mq_alloc_tag_set(&info->tag_set)) 939 return -EINVAL; 940 rq = blk_mq_init_queue(&info->tag_set); 941 if (IS_ERR(rq)) { 942 blk_mq_free_tag_set(&info->tag_set); 943 return PTR_ERR(rq); 944 } 945 946 rq->queuedata = info; 947 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 948 949 if (info->feature_discard) { 950 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); 951 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 952 rq->limits.discard_granularity = info->discard_granularity; 953 rq->limits.discard_alignment = info->discard_alignment; 954 if (info->feature_secdiscard) 955 queue_flag_set_unlocked(QUEUE_FLAG_SECERASE, rq); 956 } 957 958 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 959 blk_queue_logical_block_size(rq, sector_size); 960 blk_queue_physical_block_size(rq, physical_sector_size); 961 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512); 962 963 /* Each segment in a request is up to an aligned page in size. */ 964 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 965 blk_queue_max_segment_size(rq, PAGE_SIZE); 966 967 /* Ensure a merged request will fit in a single I/O ring slot. */ 968 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG); 969 970 /* Make sure buffer addresses are sector-aligned. */ 971 blk_queue_dma_alignment(rq, 511); 972 973 /* Make sure we don't use bounce buffers. */ 974 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); 975 976 gd->queue = rq; 977 978 return 0; 979 } 980 981 static const char *flush_info(struct blkfront_info *info) 982 { 983 if (info->feature_flush && info->feature_fua) 984 return "barrier: enabled;"; 985 else if (info->feature_flush) 986 return "flush diskcache: enabled;"; 987 else 988 return "barrier or flush: disabled;"; 989 } 990 991 static void xlvbd_flush(struct blkfront_info *info) 992 { 993 blk_queue_write_cache(info->rq, info->feature_flush ? true : false, 994 info->feature_fua ? true : false); 995 pr_info("blkfront: %s: %s %s %s %s %s\n", 996 info->gd->disk_name, flush_info(info), 997 "persistent grants:", info->feature_persistent ? 998 "enabled;" : "disabled;", "indirect descriptors:", 999 info->max_indirect_segments ? "enabled;" : "disabled;"); 1000 } 1001 1002 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 1003 { 1004 int major; 1005 major = BLKIF_MAJOR(vdevice); 1006 *minor = BLKIF_MINOR(vdevice); 1007 switch (major) { 1008 case XEN_IDE0_MAJOR: 1009 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 1010 *minor = ((*minor / 64) * PARTS_PER_DISK) + 1011 EMULATED_HD_DISK_MINOR_OFFSET; 1012 break; 1013 case XEN_IDE1_MAJOR: 1014 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 1015 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 1016 EMULATED_HD_DISK_MINOR_OFFSET; 1017 break; 1018 case XEN_SCSI_DISK0_MAJOR: 1019 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 1020 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 1021 break; 1022 case XEN_SCSI_DISK1_MAJOR: 1023 case XEN_SCSI_DISK2_MAJOR: 1024 case XEN_SCSI_DISK3_MAJOR: 1025 case XEN_SCSI_DISK4_MAJOR: 1026 case XEN_SCSI_DISK5_MAJOR: 1027 case XEN_SCSI_DISK6_MAJOR: 1028 case XEN_SCSI_DISK7_MAJOR: 1029 *offset = (*minor / PARTS_PER_DISK) + 1030 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 1031 EMULATED_SD_DISK_NAME_OFFSET; 1032 *minor = *minor + 1033 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 1034 EMULATED_SD_DISK_MINOR_OFFSET; 1035 break; 1036 case XEN_SCSI_DISK8_MAJOR: 1037 case XEN_SCSI_DISK9_MAJOR: 1038 case XEN_SCSI_DISK10_MAJOR: 1039 case XEN_SCSI_DISK11_MAJOR: 1040 case XEN_SCSI_DISK12_MAJOR: 1041 case XEN_SCSI_DISK13_MAJOR: 1042 case XEN_SCSI_DISK14_MAJOR: 1043 case XEN_SCSI_DISK15_MAJOR: 1044 *offset = (*minor / PARTS_PER_DISK) + 1045 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 1046 EMULATED_SD_DISK_NAME_OFFSET; 1047 *minor = *minor + 1048 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 1049 EMULATED_SD_DISK_MINOR_OFFSET; 1050 break; 1051 case XENVBD_MAJOR: 1052 *offset = *minor / PARTS_PER_DISK; 1053 break; 1054 default: 1055 printk(KERN_WARNING "blkfront: your disk configuration is " 1056 "incorrect, please use an xvd device instead\n"); 1057 return -ENODEV; 1058 } 1059 return 0; 1060 } 1061 1062 static char *encode_disk_name(char *ptr, unsigned int n) 1063 { 1064 if (n >= 26) 1065 ptr = encode_disk_name(ptr, n / 26 - 1); 1066 *ptr = 'a' + n % 26; 1067 return ptr + 1; 1068 } 1069 1070 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 1071 struct blkfront_info *info, 1072 u16 vdisk_info, u16 sector_size, 1073 unsigned int physical_sector_size) 1074 { 1075 struct gendisk *gd; 1076 int nr_minors = 1; 1077 int err; 1078 unsigned int offset; 1079 int minor; 1080 int nr_parts; 1081 char *ptr; 1082 1083 BUG_ON(info->gd != NULL); 1084 BUG_ON(info->rq != NULL); 1085 1086 if ((info->vdevice>>EXT_SHIFT) > 1) { 1087 /* this is above the extended range; something is wrong */ 1088 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 1089 return -ENODEV; 1090 } 1091 1092 if (!VDEV_IS_EXTENDED(info->vdevice)) { 1093 err = xen_translate_vdev(info->vdevice, &minor, &offset); 1094 if (err) 1095 return err; 1096 nr_parts = PARTS_PER_DISK; 1097 } else { 1098 minor = BLKIF_MINOR_EXT(info->vdevice); 1099 nr_parts = PARTS_PER_EXT_DISK; 1100 offset = minor / nr_parts; 1101 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 1102 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 1103 "emulated IDE disks,\n\t choose an xvd device name" 1104 "from xvde on\n", info->vdevice); 1105 } 1106 if (minor >> MINORBITS) { 1107 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 1108 info->vdevice, minor); 1109 return -ENODEV; 1110 } 1111 1112 if ((minor % nr_parts) == 0) 1113 nr_minors = nr_parts; 1114 1115 err = xlbd_reserve_minors(minor, nr_minors); 1116 if (err) 1117 goto out; 1118 err = -ENODEV; 1119 1120 gd = alloc_disk(nr_minors); 1121 if (gd == NULL) 1122 goto release; 1123 1124 strcpy(gd->disk_name, DEV_NAME); 1125 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 1126 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 1127 if (nr_minors > 1) 1128 *ptr = 0; 1129 else 1130 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 1131 "%d", minor & (nr_parts - 1)); 1132 1133 gd->major = XENVBD_MAJOR; 1134 gd->first_minor = minor; 1135 gd->fops = &xlvbd_block_fops; 1136 gd->private_data = info; 1137 set_capacity(gd, capacity); 1138 1139 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size, 1140 info->max_indirect_segments ? : 1141 BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 1142 del_gendisk(gd); 1143 goto release; 1144 } 1145 1146 info->rq = gd->queue; 1147 info->gd = gd; 1148 1149 xlvbd_flush(info); 1150 1151 if (vdisk_info & VDISK_READONLY) 1152 set_disk_ro(gd, 1); 1153 1154 if (vdisk_info & VDISK_REMOVABLE) 1155 gd->flags |= GENHD_FL_REMOVABLE; 1156 1157 if (vdisk_info & VDISK_CDROM) 1158 gd->flags |= GENHD_FL_CD; 1159 1160 return 0; 1161 1162 release: 1163 xlbd_release_minors(minor, nr_minors); 1164 out: 1165 return err; 1166 } 1167 1168 static void xlvbd_release_gendisk(struct blkfront_info *info) 1169 { 1170 unsigned int minor, nr_minors, i; 1171 1172 if (info->rq == NULL) 1173 return; 1174 1175 /* No more blkif_request(). */ 1176 blk_mq_stop_hw_queues(info->rq); 1177 1178 for (i = 0; i < info->nr_rings; i++) { 1179 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1180 1181 /* No more gnttab callback work. */ 1182 gnttab_cancel_free_callback(&rinfo->callback); 1183 1184 /* Flush gnttab callback work. Must be done with no locks held. */ 1185 flush_work(&rinfo->work); 1186 } 1187 1188 del_gendisk(info->gd); 1189 1190 minor = info->gd->first_minor; 1191 nr_minors = info->gd->minors; 1192 xlbd_release_minors(minor, nr_minors); 1193 1194 blk_cleanup_queue(info->rq); 1195 blk_mq_free_tag_set(&info->tag_set); 1196 info->rq = NULL; 1197 1198 put_disk(info->gd); 1199 info->gd = NULL; 1200 } 1201 1202 /* Already hold rinfo->ring_lock. */ 1203 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo) 1204 { 1205 if (!RING_FULL(&rinfo->ring)) 1206 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true); 1207 } 1208 1209 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo) 1210 { 1211 unsigned long flags; 1212 1213 spin_lock_irqsave(&rinfo->ring_lock, flags); 1214 kick_pending_request_queues_locked(rinfo); 1215 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1216 } 1217 1218 static void blkif_restart_queue(struct work_struct *work) 1219 { 1220 struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work); 1221 1222 if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED) 1223 kick_pending_request_queues(rinfo); 1224 } 1225 1226 static void blkif_free_ring(struct blkfront_ring_info *rinfo) 1227 { 1228 struct grant *persistent_gnt, *n; 1229 struct blkfront_info *info = rinfo->dev_info; 1230 int i, j, segs; 1231 1232 /* 1233 * Remove indirect pages, this only happens when using indirect 1234 * descriptors but not persistent grants 1235 */ 1236 if (!list_empty(&rinfo->indirect_pages)) { 1237 struct page *indirect_page, *n; 1238 1239 BUG_ON(info->feature_persistent); 1240 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 1241 list_del(&indirect_page->lru); 1242 __free_page(indirect_page); 1243 } 1244 } 1245 1246 /* Remove all persistent grants. */ 1247 if (!list_empty(&rinfo->grants)) { 1248 list_for_each_entry_safe(persistent_gnt, n, 1249 &rinfo->grants, node) { 1250 list_del(&persistent_gnt->node); 1251 if (persistent_gnt->gref != GRANT_INVALID_REF) { 1252 gnttab_end_foreign_access(persistent_gnt->gref, 1253 0, 0UL); 1254 rinfo->persistent_gnts_c--; 1255 } 1256 if (info->feature_persistent) 1257 __free_page(persistent_gnt->page); 1258 kfree(persistent_gnt); 1259 } 1260 } 1261 BUG_ON(rinfo->persistent_gnts_c != 0); 1262 1263 for (i = 0; i < BLK_RING_SIZE(info); i++) { 1264 /* 1265 * Clear persistent grants present in requests already 1266 * on the shared ring 1267 */ 1268 if (!rinfo->shadow[i].request) 1269 goto free_shadow; 1270 1271 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 1272 rinfo->shadow[i].req.u.indirect.nr_segments : 1273 rinfo->shadow[i].req.u.rw.nr_segments; 1274 for (j = 0; j < segs; j++) { 1275 persistent_gnt = rinfo->shadow[i].grants_used[j]; 1276 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1277 if (info->feature_persistent) 1278 __free_page(persistent_gnt->page); 1279 kfree(persistent_gnt); 1280 } 1281 1282 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT) 1283 /* 1284 * If this is not an indirect operation don't try to 1285 * free indirect segments 1286 */ 1287 goto free_shadow; 1288 1289 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 1290 persistent_gnt = rinfo->shadow[i].indirect_grants[j]; 1291 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 1292 __free_page(persistent_gnt->page); 1293 kfree(persistent_gnt); 1294 } 1295 1296 free_shadow: 1297 kfree(rinfo->shadow[i].grants_used); 1298 rinfo->shadow[i].grants_used = NULL; 1299 kfree(rinfo->shadow[i].indirect_grants); 1300 rinfo->shadow[i].indirect_grants = NULL; 1301 kfree(rinfo->shadow[i].sg); 1302 rinfo->shadow[i].sg = NULL; 1303 } 1304 1305 /* No more gnttab callback work. */ 1306 gnttab_cancel_free_callback(&rinfo->callback); 1307 1308 /* Flush gnttab callback work. Must be done with no locks held. */ 1309 flush_work(&rinfo->work); 1310 1311 /* Free resources associated with old device channel. */ 1312 for (i = 0; i < info->nr_ring_pages; i++) { 1313 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) { 1314 gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0); 1315 rinfo->ring_ref[i] = GRANT_INVALID_REF; 1316 } 1317 } 1318 free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE)); 1319 rinfo->ring.sring = NULL; 1320 1321 if (rinfo->irq) 1322 unbind_from_irqhandler(rinfo->irq, rinfo); 1323 rinfo->evtchn = rinfo->irq = 0; 1324 } 1325 1326 static void blkif_free(struct blkfront_info *info, int suspend) 1327 { 1328 unsigned int i; 1329 1330 /* Prevent new requests being issued until we fix things up. */ 1331 info->connected = suspend ? 1332 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 1333 /* No more blkif_request(). */ 1334 if (info->rq) 1335 blk_mq_stop_hw_queues(info->rq); 1336 1337 for (i = 0; i < info->nr_rings; i++) 1338 blkif_free_ring(&info->rinfo[i]); 1339 1340 kfree(info->rinfo); 1341 info->rinfo = NULL; 1342 info->nr_rings = 0; 1343 } 1344 1345 struct copy_from_grant { 1346 const struct blk_shadow *s; 1347 unsigned int grant_idx; 1348 unsigned int bvec_offset; 1349 char *bvec_data; 1350 }; 1351 1352 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset, 1353 unsigned int len, void *data) 1354 { 1355 struct copy_from_grant *info = data; 1356 char *shared_data; 1357 /* Convenient aliases */ 1358 const struct blk_shadow *s = info->s; 1359 1360 shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page); 1361 1362 memcpy(info->bvec_data + info->bvec_offset, 1363 shared_data + offset, len); 1364 1365 info->bvec_offset += len; 1366 info->grant_idx++; 1367 1368 kunmap_atomic(shared_data); 1369 } 1370 1371 static enum blk_req_status blkif_rsp_to_req_status(int rsp) 1372 { 1373 switch (rsp) 1374 { 1375 case BLKIF_RSP_OKAY: 1376 return REQ_DONE; 1377 case BLKIF_RSP_EOPNOTSUPP: 1378 return REQ_EOPNOTSUPP; 1379 case BLKIF_RSP_ERROR: 1380 /* Fallthrough. */ 1381 default: 1382 return REQ_ERROR; 1383 } 1384 } 1385 1386 /* 1387 * Get the final status of the block request based on two ring response 1388 */ 1389 static int blkif_get_final_status(enum blk_req_status s1, 1390 enum blk_req_status s2) 1391 { 1392 BUG_ON(s1 == REQ_WAITING); 1393 BUG_ON(s2 == REQ_WAITING); 1394 1395 if (s1 == REQ_ERROR || s2 == REQ_ERROR) 1396 return BLKIF_RSP_ERROR; 1397 else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP) 1398 return BLKIF_RSP_EOPNOTSUPP; 1399 return BLKIF_RSP_OKAY; 1400 } 1401 1402 static bool blkif_completion(unsigned long *id, 1403 struct blkfront_ring_info *rinfo, 1404 struct blkif_response *bret) 1405 { 1406 int i = 0; 1407 struct scatterlist *sg; 1408 int num_sg, num_grant; 1409 struct blkfront_info *info = rinfo->dev_info; 1410 struct blk_shadow *s = &rinfo->shadow[*id]; 1411 struct copy_from_grant data = { 1412 .grant_idx = 0, 1413 }; 1414 1415 num_grant = s->req.operation == BLKIF_OP_INDIRECT ? 1416 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1417 1418 /* The I/O request may be split in two. */ 1419 if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) { 1420 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id]; 1421 1422 /* Keep the status of the current response in shadow. */ 1423 s->status = blkif_rsp_to_req_status(bret->status); 1424 1425 /* Wait the second response if not yet here. */ 1426 if (s2->status == REQ_WAITING) 1427 return 0; 1428 1429 bret->status = blkif_get_final_status(s->status, 1430 s2->status); 1431 1432 /* 1433 * All the grants is stored in the first shadow in order 1434 * to make the completion code simpler. 1435 */ 1436 num_grant += s2->req.u.rw.nr_segments; 1437 1438 /* 1439 * The two responses may not come in order. Only the 1440 * first request will store the scatter-gather list. 1441 */ 1442 if (s2->num_sg != 0) { 1443 /* Update "id" with the ID of the first response. */ 1444 *id = s->associated_id; 1445 s = s2; 1446 } 1447 1448 /* 1449 * We don't need anymore the second request, so recycling 1450 * it now. 1451 */ 1452 if (add_id_to_freelist(rinfo, s->associated_id)) 1453 WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n", 1454 info->gd->disk_name, s->associated_id); 1455 } 1456 1457 data.s = s; 1458 num_sg = s->num_sg; 1459 1460 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { 1461 for_each_sg(s->sg, sg, num_sg, i) { 1462 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1463 1464 data.bvec_offset = sg->offset; 1465 data.bvec_data = kmap_atomic(sg_page(sg)); 1466 1467 gnttab_foreach_grant_in_range(sg_page(sg), 1468 sg->offset, 1469 sg->length, 1470 blkif_copy_from_grant, 1471 &data); 1472 1473 kunmap_atomic(data.bvec_data); 1474 } 1475 } 1476 /* Add the persistent grant into the list of free grants */ 1477 for (i = 0; i < num_grant; i++) { 1478 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) { 1479 /* 1480 * If the grant is still mapped by the backend (the 1481 * backend has chosen to make this grant persistent) 1482 * we add it at the head of the list, so it will be 1483 * reused first. 1484 */ 1485 if (!info->feature_persistent) 1486 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1487 s->grants_used[i]->gref); 1488 list_add(&s->grants_used[i]->node, &rinfo->grants); 1489 rinfo->persistent_gnts_c++; 1490 } else { 1491 /* 1492 * If the grant is not mapped by the backend we end the 1493 * foreign access and add it to the tail of the list, 1494 * so it will not be picked again unless we run out of 1495 * persistent grants. 1496 */ 1497 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); 1498 s->grants_used[i]->gref = GRANT_INVALID_REF; 1499 list_add_tail(&s->grants_used[i]->node, &rinfo->grants); 1500 } 1501 } 1502 if (s->req.operation == BLKIF_OP_INDIRECT) { 1503 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) { 1504 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { 1505 if (!info->feature_persistent) 1506 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1507 s->indirect_grants[i]->gref); 1508 list_add(&s->indirect_grants[i]->node, &rinfo->grants); 1509 rinfo->persistent_gnts_c++; 1510 } else { 1511 struct page *indirect_page; 1512 1513 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); 1514 /* 1515 * Add the used indirect page back to the list of 1516 * available pages for indirect grefs. 1517 */ 1518 if (!info->feature_persistent) { 1519 indirect_page = s->indirect_grants[i]->page; 1520 list_add(&indirect_page->lru, &rinfo->indirect_pages); 1521 } 1522 s->indirect_grants[i]->gref = GRANT_INVALID_REF; 1523 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants); 1524 } 1525 } 1526 } 1527 1528 return 1; 1529 } 1530 1531 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1532 { 1533 struct request *req; 1534 struct blkif_response *bret; 1535 RING_IDX i, rp; 1536 unsigned long flags; 1537 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id; 1538 struct blkfront_info *info = rinfo->dev_info; 1539 int error; 1540 1541 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 1542 return IRQ_HANDLED; 1543 1544 spin_lock_irqsave(&rinfo->ring_lock, flags); 1545 again: 1546 rp = rinfo->ring.sring->rsp_prod; 1547 rmb(); /* Ensure we see queued responses up to 'rp'. */ 1548 1549 for (i = rinfo->ring.rsp_cons; i != rp; i++) { 1550 unsigned long id; 1551 1552 bret = RING_GET_RESPONSE(&rinfo->ring, i); 1553 id = bret->id; 1554 /* 1555 * The backend has messed up and given us an id that we would 1556 * never have given to it (we stamp it up to BLK_RING_SIZE - 1557 * look in get_id_from_freelist. 1558 */ 1559 if (id >= BLK_RING_SIZE(info)) { 1560 WARN(1, "%s: response to %s has incorrect id (%ld)\n", 1561 info->gd->disk_name, op_name(bret->operation), id); 1562 /* We can't safely get the 'struct request' as 1563 * the id is busted. */ 1564 continue; 1565 } 1566 req = rinfo->shadow[id].request; 1567 1568 if (bret->operation != BLKIF_OP_DISCARD) { 1569 /* 1570 * We may need to wait for an extra response if the 1571 * I/O request is split in 2 1572 */ 1573 if (!blkif_completion(&id, rinfo, bret)) 1574 continue; 1575 } 1576 1577 if (add_id_to_freelist(rinfo, id)) { 1578 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1579 info->gd->disk_name, op_name(bret->operation), id); 1580 continue; 1581 } 1582 1583 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; 1584 switch (bret->operation) { 1585 case BLKIF_OP_DISCARD: 1586 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1587 struct request_queue *rq = info->rq; 1588 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1589 info->gd->disk_name, op_name(bret->operation)); 1590 error = -EOPNOTSUPP; 1591 info->feature_discard = 0; 1592 info->feature_secdiscard = 0; 1593 queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 1594 queue_flag_clear(QUEUE_FLAG_SECERASE, rq); 1595 } 1596 blk_mq_complete_request(req, error); 1597 break; 1598 case BLKIF_OP_FLUSH_DISKCACHE: 1599 case BLKIF_OP_WRITE_BARRIER: 1600 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1601 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1602 info->gd->disk_name, op_name(bret->operation)); 1603 error = -EOPNOTSUPP; 1604 } 1605 if (unlikely(bret->status == BLKIF_RSP_ERROR && 1606 rinfo->shadow[id].req.u.rw.nr_segments == 0)) { 1607 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", 1608 info->gd->disk_name, op_name(bret->operation)); 1609 error = -EOPNOTSUPP; 1610 } 1611 if (unlikely(error)) { 1612 if (error == -EOPNOTSUPP) 1613 error = 0; 1614 info->feature_fua = 0; 1615 info->feature_flush = 0; 1616 xlvbd_flush(info); 1617 } 1618 /* fall through */ 1619 case BLKIF_OP_READ: 1620 case BLKIF_OP_WRITE: 1621 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 1622 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 1623 "request: %x\n", bret->status); 1624 1625 blk_mq_complete_request(req, error); 1626 break; 1627 default: 1628 BUG(); 1629 } 1630 } 1631 1632 rinfo->ring.rsp_cons = i; 1633 1634 if (i != rinfo->ring.req_prod_pvt) { 1635 int more_to_do; 1636 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do); 1637 if (more_to_do) 1638 goto again; 1639 } else 1640 rinfo->ring.sring->rsp_event = i + 1; 1641 1642 kick_pending_request_queues_locked(rinfo); 1643 1644 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 1645 1646 return IRQ_HANDLED; 1647 } 1648 1649 1650 static int setup_blkring(struct xenbus_device *dev, 1651 struct blkfront_ring_info *rinfo) 1652 { 1653 struct blkif_sring *sring; 1654 int err, i; 1655 struct blkfront_info *info = rinfo->dev_info; 1656 unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE; 1657 grant_ref_t gref[XENBUS_MAX_RING_GRANTS]; 1658 1659 for (i = 0; i < info->nr_ring_pages; i++) 1660 rinfo->ring_ref[i] = GRANT_INVALID_REF; 1661 1662 sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH, 1663 get_order(ring_size)); 1664 if (!sring) { 1665 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1666 return -ENOMEM; 1667 } 1668 SHARED_RING_INIT(sring); 1669 FRONT_RING_INIT(&rinfo->ring, sring, ring_size); 1670 1671 err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref); 1672 if (err < 0) { 1673 free_pages((unsigned long)sring, get_order(ring_size)); 1674 rinfo->ring.sring = NULL; 1675 goto fail; 1676 } 1677 for (i = 0; i < info->nr_ring_pages; i++) 1678 rinfo->ring_ref[i] = gref[i]; 1679 1680 err = xenbus_alloc_evtchn(dev, &rinfo->evtchn); 1681 if (err) 1682 goto fail; 1683 1684 err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0, 1685 "blkif", rinfo); 1686 if (err <= 0) { 1687 xenbus_dev_fatal(dev, err, 1688 "bind_evtchn_to_irqhandler failed"); 1689 goto fail; 1690 } 1691 rinfo->irq = err; 1692 1693 return 0; 1694 fail: 1695 blkif_free(info, 0); 1696 return err; 1697 } 1698 1699 /* 1700 * Write out per-ring/queue nodes including ring-ref and event-channel, and each 1701 * ring buffer may have multi pages depending on ->nr_ring_pages. 1702 */ 1703 static int write_per_ring_nodes(struct xenbus_transaction xbt, 1704 struct blkfront_ring_info *rinfo, const char *dir) 1705 { 1706 int err; 1707 unsigned int i; 1708 const char *message = NULL; 1709 struct blkfront_info *info = rinfo->dev_info; 1710 1711 if (info->nr_ring_pages == 1) { 1712 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]); 1713 if (err) { 1714 message = "writing ring-ref"; 1715 goto abort_transaction; 1716 } 1717 } else { 1718 for (i = 0; i < info->nr_ring_pages; i++) { 1719 char ring_ref_name[RINGREF_NAME_LEN]; 1720 1721 snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i); 1722 err = xenbus_printf(xbt, dir, ring_ref_name, 1723 "%u", rinfo->ring_ref[i]); 1724 if (err) { 1725 message = "writing ring-ref"; 1726 goto abort_transaction; 1727 } 1728 } 1729 } 1730 1731 err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn); 1732 if (err) { 1733 message = "writing event-channel"; 1734 goto abort_transaction; 1735 } 1736 1737 return 0; 1738 1739 abort_transaction: 1740 xenbus_transaction_end(xbt, 1); 1741 if (message) 1742 xenbus_dev_fatal(info->xbdev, err, "%s", message); 1743 1744 return err; 1745 } 1746 1747 /* Common code used when first setting up, and when resuming. */ 1748 static int talk_to_blkback(struct xenbus_device *dev, 1749 struct blkfront_info *info) 1750 { 1751 const char *message = NULL; 1752 struct xenbus_transaction xbt; 1753 int err; 1754 unsigned int i, max_page_order = 0; 1755 unsigned int ring_page_order = 0; 1756 1757 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1758 "max-ring-page-order", "%u", &max_page_order); 1759 if (err != 1) 1760 info->nr_ring_pages = 1; 1761 else { 1762 ring_page_order = min(xen_blkif_max_ring_order, max_page_order); 1763 info->nr_ring_pages = 1 << ring_page_order; 1764 } 1765 1766 for (i = 0; i < info->nr_rings; i++) { 1767 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1768 1769 /* Create shared ring, alloc event channel. */ 1770 err = setup_blkring(dev, rinfo); 1771 if (err) 1772 goto destroy_blkring; 1773 } 1774 1775 again: 1776 err = xenbus_transaction_start(&xbt); 1777 if (err) { 1778 xenbus_dev_fatal(dev, err, "starting transaction"); 1779 goto destroy_blkring; 1780 } 1781 1782 if (info->nr_ring_pages > 1) { 1783 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u", 1784 ring_page_order); 1785 if (err) { 1786 message = "writing ring-page-order"; 1787 goto abort_transaction; 1788 } 1789 } 1790 1791 /* We already got the number of queues/rings in _probe */ 1792 if (info->nr_rings == 1) { 1793 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename); 1794 if (err) 1795 goto destroy_blkring; 1796 } else { 1797 char *path; 1798 size_t pathsize; 1799 1800 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u", 1801 info->nr_rings); 1802 if (err) { 1803 message = "writing multi-queue-num-queues"; 1804 goto abort_transaction; 1805 } 1806 1807 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN; 1808 path = kmalloc(pathsize, GFP_KERNEL); 1809 if (!path) { 1810 err = -ENOMEM; 1811 message = "ENOMEM while writing ring references"; 1812 goto abort_transaction; 1813 } 1814 1815 for (i = 0; i < info->nr_rings; i++) { 1816 memset(path, 0, pathsize); 1817 snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i); 1818 err = write_per_ring_nodes(xbt, &info->rinfo[i], path); 1819 if (err) { 1820 kfree(path); 1821 goto destroy_blkring; 1822 } 1823 } 1824 kfree(path); 1825 } 1826 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1827 XEN_IO_PROTO_ABI_NATIVE); 1828 if (err) { 1829 message = "writing protocol"; 1830 goto abort_transaction; 1831 } 1832 err = xenbus_printf(xbt, dev->nodename, 1833 "feature-persistent", "%u", 1); 1834 if (err) 1835 dev_warn(&dev->dev, 1836 "writing persistent grants feature to xenbus"); 1837 1838 err = xenbus_transaction_end(xbt, 0); 1839 if (err) { 1840 if (err == -EAGAIN) 1841 goto again; 1842 xenbus_dev_fatal(dev, err, "completing transaction"); 1843 goto destroy_blkring; 1844 } 1845 1846 for (i = 0; i < info->nr_rings; i++) { 1847 unsigned int j; 1848 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 1849 1850 for (j = 0; j < BLK_RING_SIZE(info); j++) 1851 rinfo->shadow[j].req.u.rw.id = j + 1; 1852 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 1853 } 1854 xenbus_switch_state(dev, XenbusStateInitialised); 1855 1856 return 0; 1857 1858 abort_transaction: 1859 xenbus_transaction_end(xbt, 1); 1860 if (message) 1861 xenbus_dev_fatal(dev, err, "%s", message); 1862 destroy_blkring: 1863 blkif_free(info, 0); 1864 1865 kfree(info); 1866 dev_set_drvdata(&dev->dev, NULL); 1867 1868 return err; 1869 } 1870 1871 static int negotiate_mq(struct blkfront_info *info) 1872 { 1873 unsigned int backend_max_queues = 0; 1874 int err; 1875 unsigned int i; 1876 1877 BUG_ON(info->nr_rings); 1878 1879 /* Check if backend supports multiple queues. */ 1880 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1881 "multi-queue-max-queues", "%u", &backend_max_queues); 1882 if (err < 0) 1883 backend_max_queues = 1; 1884 1885 info->nr_rings = min(backend_max_queues, xen_blkif_max_queues); 1886 /* We need at least one ring. */ 1887 if (!info->nr_rings) 1888 info->nr_rings = 1; 1889 1890 info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL); 1891 if (!info->rinfo) { 1892 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure"); 1893 return -ENOMEM; 1894 } 1895 1896 for (i = 0; i < info->nr_rings; i++) { 1897 struct blkfront_ring_info *rinfo; 1898 1899 rinfo = &info->rinfo[i]; 1900 INIT_LIST_HEAD(&rinfo->indirect_pages); 1901 INIT_LIST_HEAD(&rinfo->grants); 1902 rinfo->dev_info = info; 1903 INIT_WORK(&rinfo->work, blkif_restart_queue); 1904 spin_lock_init(&rinfo->ring_lock); 1905 } 1906 return 0; 1907 } 1908 /** 1909 * Entry point to this code when a new device is created. Allocate the basic 1910 * structures and the ring buffer for communication with the backend, and 1911 * inform the backend of the appropriate details for those. Switch to 1912 * Initialised state. 1913 */ 1914 static int blkfront_probe(struct xenbus_device *dev, 1915 const struct xenbus_device_id *id) 1916 { 1917 int err, vdevice; 1918 struct blkfront_info *info; 1919 1920 /* FIXME: Use dynamic device id if this is not set. */ 1921 err = xenbus_scanf(XBT_NIL, dev->nodename, 1922 "virtual-device", "%i", &vdevice); 1923 if (err != 1) { 1924 /* go looking in the extended area instead */ 1925 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1926 "%i", &vdevice); 1927 if (err != 1) { 1928 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1929 return err; 1930 } 1931 } 1932 1933 if (xen_hvm_domain()) { 1934 char *type; 1935 int len; 1936 /* no unplug has been done: do not hook devices != xen vbds */ 1937 if (xen_has_pv_and_legacy_disk_devices()) { 1938 int major; 1939 1940 if (!VDEV_IS_EXTENDED(vdevice)) 1941 major = BLKIF_MAJOR(vdevice); 1942 else 1943 major = XENVBD_MAJOR; 1944 1945 if (major != XENVBD_MAJOR) { 1946 printk(KERN_INFO 1947 "%s: HVM does not support vbd %d as xen block device\n", 1948 __func__, vdevice); 1949 return -ENODEV; 1950 } 1951 } 1952 /* do not create a PV cdrom device if we are an HVM guest */ 1953 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1954 if (IS_ERR(type)) 1955 return -ENODEV; 1956 if (strncmp(type, "cdrom", 5) == 0) { 1957 kfree(type); 1958 return -ENODEV; 1959 } 1960 kfree(type); 1961 } 1962 info = kzalloc(sizeof(*info), GFP_KERNEL); 1963 if (!info) { 1964 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1965 return -ENOMEM; 1966 } 1967 1968 info->xbdev = dev; 1969 err = negotiate_mq(info); 1970 if (err) { 1971 kfree(info); 1972 return err; 1973 } 1974 1975 mutex_init(&info->mutex); 1976 info->vdevice = vdevice; 1977 info->connected = BLKIF_STATE_DISCONNECTED; 1978 1979 /* Front end dir is a number, which is used as the id. */ 1980 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1981 dev_set_drvdata(&dev->dev, info); 1982 1983 return 0; 1984 } 1985 1986 static void split_bio_end(struct bio *bio) 1987 { 1988 struct split_bio *split_bio = bio->bi_private; 1989 1990 if (atomic_dec_and_test(&split_bio->pending)) { 1991 split_bio->bio->bi_phys_segments = 0; 1992 split_bio->bio->bi_error = bio->bi_error; 1993 bio_endio(split_bio->bio); 1994 kfree(split_bio); 1995 } 1996 bio_put(bio); 1997 } 1998 1999 static int blkif_recover(struct blkfront_info *info) 2000 { 2001 unsigned int i, r_index; 2002 struct request *req, *n; 2003 int rc; 2004 struct bio *bio, *cloned_bio; 2005 unsigned int segs, offset; 2006 int pending, size; 2007 struct split_bio *split_bio; 2008 2009 blkfront_gather_backend_features(info); 2010 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 2011 blk_queue_max_segments(info->rq, segs); 2012 2013 for (r_index = 0; r_index < info->nr_rings; r_index++) { 2014 struct blkfront_ring_info *rinfo = &info->rinfo[r_index]; 2015 2016 rc = blkfront_setup_indirect(rinfo); 2017 if (rc) 2018 return rc; 2019 } 2020 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2021 2022 /* Now safe for us to use the shared ring */ 2023 info->connected = BLKIF_STATE_CONNECTED; 2024 2025 for (r_index = 0; r_index < info->nr_rings; r_index++) { 2026 struct blkfront_ring_info *rinfo; 2027 2028 rinfo = &info->rinfo[r_index]; 2029 /* Kick any other new requests queued since we resumed */ 2030 kick_pending_request_queues(rinfo); 2031 } 2032 2033 list_for_each_entry_safe(req, n, &info->requests, queuelist) { 2034 /* Requeue pending requests (flush or discard) */ 2035 list_del_init(&req->queuelist); 2036 BUG_ON(req->nr_phys_segments > segs); 2037 blk_mq_requeue_request(req); 2038 } 2039 blk_mq_kick_requeue_list(info->rq); 2040 2041 while ((bio = bio_list_pop(&info->bio_list)) != NULL) { 2042 /* Traverse the list of pending bios and re-queue them */ 2043 if (bio_segments(bio) > segs) { 2044 /* 2045 * This bio has more segments than what we can 2046 * handle, we have to split it. 2047 */ 2048 pending = (bio_segments(bio) + segs - 1) / segs; 2049 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO); 2050 BUG_ON(split_bio == NULL); 2051 atomic_set(&split_bio->pending, pending); 2052 split_bio->bio = bio; 2053 for (i = 0; i < pending; i++) { 2054 offset = (i * segs * XEN_PAGE_SIZE) >> 9; 2055 size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9, 2056 (unsigned int)bio_sectors(bio) - offset); 2057 cloned_bio = bio_clone(bio, GFP_NOIO); 2058 BUG_ON(cloned_bio == NULL); 2059 bio_trim(cloned_bio, offset, size); 2060 cloned_bio->bi_private = split_bio; 2061 cloned_bio->bi_end_io = split_bio_end; 2062 submit_bio(cloned_bio); 2063 } 2064 /* 2065 * Now we have to wait for all those smaller bios to 2066 * end, so we can also end the "parent" bio. 2067 */ 2068 continue; 2069 } 2070 /* We don't need to split this bio */ 2071 submit_bio(bio); 2072 } 2073 2074 return 0; 2075 } 2076 2077 /** 2078 * We are reconnecting to the backend, due to a suspend/resume, or a backend 2079 * driver restart. We tear down our blkif structure and recreate it, but 2080 * leave the device-layer structures intact so that this is transparent to the 2081 * rest of the kernel. 2082 */ 2083 static int blkfront_resume(struct xenbus_device *dev) 2084 { 2085 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2086 int err = 0; 2087 unsigned int i, j; 2088 2089 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 2090 2091 bio_list_init(&info->bio_list); 2092 INIT_LIST_HEAD(&info->requests); 2093 for (i = 0; i < info->nr_rings; i++) { 2094 struct blkfront_ring_info *rinfo = &info->rinfo[i]; 2095 struct bio_list merge_bio; 2096 struct blk_shadow *shadow = rinfo->shadow; 2097 2098 for (j = 0; j < BLK_RING_SIZE(info); j++) { 2099 /* Not in use? */ 2100 if (!shadow[j].request) 2101 continue; 2102 2103 /* 2104 * Get the bios in the request so we can re-queue them. 2105 */ 2106 if (req_op(shadow[i].request) == REQ_OP_FLUSH || 2107 req_op(shadow[i].request) == REQ_OP_DISCARD || 2108 req_op(shadow[i].request) == REQ_OP_SECURE_ERASE || 2109 shadow[j].request->cmd_flags & REQ_FUA) { 2110 /* 2111 * Flush operations don't contain bios, so 2112 * we need to requeue the whole request 2113 * 2114 * XXX: but this doesn't make any sense for a 2115 * write with the FUA flag set.. 2116 */ 2117 list_add(&shadow[j].request->queuelist, &info->requests); 2118 continue; 2119 } 2120 merge_bio.head = shadow[j].request->bio; 2121 merge_bio.tail = shadow[j].request->biotail; 2122 bio_list_merge(&info->bio_list, &merge_bio); 2123 shadow[j].request->bio = NULL; 2124 blk_mq_end_request(shadow[j].request, 0); 2125 } 2126 } 2127 2128 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 2129 2130 err = negotiate_mq(info); 2131 if (err) 2132 return err; 2133 2134 err = talk_to_blkback(dev, info); 2135 if (!err) 2136 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings); 2137 2138 /* 2139 * We have to wait for the backend to switch to 2140 * connected state, since we want to read which 2141 * features it supports. 2142 */ 2143 2144 return err; 2145 } 2146 2147 static void blkfront_closing(struct blkfront_info *info) 2148 { 2149 struct xenbus_device *xbdev = info->xbdev; 2150 struct block_device *bdev = NULL; 2151 2152 mutex_lock(&info->mutex); 2153 2154 if (xbdev->state == XenbusStateClosing) { 2155 mutex_unlock(&info->mutex); 2156 return; 2157 } 2158 2159 if (info->gd) 2160 bdev = bdget_disk(info->gd, 0); 2161 2162 mutex_unlock(&info->mutex); 2163 2164 if (!bdev) { 2165 xenbus_frontend_closed(xbdev); 2166 return; 2167 } 2168 2169 mutex_lock(&bdev->bd_mutex); 2170 2171 if (bdev->bd_openers) { 2172 xenbus_dev_error(xbdev, -EBUSY, 2173 "Device in use; refusing to close"); 2174 xenbus_switch_state(xbdev, XenbusStateClosing); 2175 } else { 2176 xlvbd_release_gendisk(info); 2177 xenbus_frontend_closed(xbdev); 2178 } 2179 2180 mutex_unlock(&bdev->bd_mutex); 2181 bdput(bdev); 2182 } 2183 2184 static void blkfront_setup_discard(struct blkfront_info *info) 2185 { 2186 int err; 2187 unsigned int discard_granularity; 2188 unsigned int discard_alignment; 2189 unsigned int discard_secure; 2190 2191 info->feature_discard = 1; 2192 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2193 "discard-granularity", "%u", &discard_granularity, 2194 "discard-alignment", "%u", &discard_alignment, 2195 NULL); 2196 if (!err) { 2197 info->discard_granularity = discard_granularity; 2198 info->discard_alignment = discard_alignment; 2199 } 2200 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2201 "discard-secure", "%u", &discard_secure); 2202 if (err > 0) 2203 info->feature_secdiscard = !!discard_secure; 2204 } 2205 2206 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo) 2207 { 2208 unsigned int psegs, grants; 2209 int err, i; 2210 struct blkfront_info *info = rinfo->dev_info; 2211 2212 if (info->max_indirect_segments == 0) { 2213 if (!HAS_EXTRA_REQ) 2214 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2215 else { 2216 /* 2217 * When an extra req is required, the maximum 2218 * grants supported is related to the size of the 2219 * Linux block segment. 2220 */ 2221 grants = GRANTS_PER_PSEG; 2222 } 2223 } 2224 else 2225 grants = info->max_indirect_segments; 2226 psegs = grants / GRANTS_PER_PSEG; 2227 2228 err = fill_grant_buffer(rinfo, 2229 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info)); 2230 if (err) 2231 goto out_of_memory; 2232 2233 if (!info->feature_persistent && info->max_indirect_segments) { 2234 /* 2235 * We are using indirect descriptors but not persistent 2236 * grants, we need to allocate a set of pages that can be 2237 * used for mapping indirect grefs 2238 */ 2239 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info); 2240 2241 BUG_ON(!list_empty(&rinfo->indirect_pages)); 2242 for (i = 0; i < num; i++) { 2243 struct page *indirect_page = alloc_page(GFP_NOIO); 2244 if (!indirect_page) 2245 goto out_of_memory; 2246 list_add(&indirect_page->lru, &rinfo->indirect_pages); 2247 } 2248 } 2249 2250 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2251 rinfo->shadow[i].grants_used = kzalloc( 2252 sizeof(rinfo->shadow[i].grants_used[0]) * grants, 2253 GFP_NOIO); 2254 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO); 2255 if (info->max_indirect_segments) 2256 rinfo->shadow[i].indirect_grants = kzalloc( 2257 sizeof(rinfo->shadow[i].indirect_grants[0]) * 2258 INDIRECT_GREFS(grants), 2259 GFP_NOIO); 2260 if ((rinfo->shadow[i].grants_used == NULL) || 2261 (rinfo->shadow[i].sg == NULL) || 2262 (info->max_indirect_segments && 2263 (rinfo->shadow[i].indirect_grants == NULL))) 2264 goto out_of_memory; 2265 sg_init_table(rinfo->shadow[i].sg, psegs); 2266 } 2267 2268 2269 return 0; 2270 2271 out_of_memory: 2272 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2273 kfree(rinfo->shadow[i].grants_used); 2274 rinfo->shadow[i].grants_used = NULL; 2275 kfree(rinfo->shadow[i].sg); 2276 rinfo->shadow[i].sg = NULL; 2277 kfree(rinfo->shadow[i].indirect_grants); 2278 rinfo->shadow[i].indirect_grants = NULL; 2279 } 2280 if (!list_empty(&rinfo->indirect_pages)) { 2281 struct page *indirect_page, *n; 2282 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 2283 list_del(&indirect_page->lru); 2284 __free_page(indirect_page); 2285 } 2286 } 2287 return -ENOMEM; 2288 } 2289 2290 /* 2291 * Gather all backend feature-* 2292 */ 2293 static void blkfront_gather_backend_features(struct blkfront_info *info) 2294 { 2295 int err; 2296 int barrier, flush, discard, persistent; 2297 unsigned int indirect_segments; 2298 2299 info->feature_flush = 0; 2300 info->feature_fua = 0; 2301 2302 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2303 "feature-barrier", "%d", &barrier); 2304 2305 /* 2306 * If there's no "feature-barrier" defined, then it means 2307 * we're dealing with a very old backend which writes 2308 * synchronously; nothing to do. 2309 * 2310 * If there are barriers, then we use flush. 2311 */ 2312 if (err > 0 && barrier) { 2313 info->feature_flush = 1; 2314 info->feature_fua = 1; 2315 } 2316 2317 /* 2318 * And if there is "feature-flush-cache" use that above 2319 * barriers. 2320 */ 2321 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2322 "feature-flush-cache", "%d", &flush); 2323 2324 if (err > 0 && flush) { 2325 info->feature_flush = 1; 2326 info->feature_fua = 0; 2327 } 2328 2329 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2330 "feature-discard", "%d", &discard); 2331 2332 if (err > 0 && discard) 2333 blkfront_setup_discard(info); 2334 2335 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2336 "feature-persistent", "%d", &persistent); 2337 if (err <= 0) 2338 info->feature_persistent = 0; 2339 else 2340 info->feature_persistent = persistent; 2341 2342 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2343 "feature-max-indirect-segments", "%u", 2344 &indirect_segments); 2345 if (err <= 0) 2346 info->max_indirect_segments = 0; 2347 else 2348 info->max_indirect_segments = min(indirect_segments, 2349 xen_blkif_max_segments); 2350 } 2351 2352 /* 2353 * Invoked when the backend is finally 'ready' (and has told produced 2354 * the details about the physical device - #sectors, size, etc). 2355 */ 2356 static void blkfront_connect(struct blkfront_info *info) 2357 { 2358 unsigned long long sectors; 2359 unsigned long sector_size; 2360 unsigned int physical_sector_size; 2361 unsigned int binfo; 2362 int err, i; 2363 2364 switch (info->connected) { 2365 case BLKIF_STATE_CONNECTED: 2366 /* 2367 * Potentially, the back-end may be signalling 2368 * a capacity change; update the capacity. 2369 */ 2370 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2371 "sectors", "%Lu", §ors); 2372 if (XENBUS_EXIST_ERR(err)) 2373 return; 2374 printk(KERN_INFO "Setting capacity to %Lu\n", 2375 sectors); 2376 set_capacity(info->gd, sectors); 2377 revalidate_disk(info->gd); 2378 2379 return; 2380 case BLKIF_STATE_SUSPENDED: 2381 /* 2382 * If we are recovering from suspension, we need to wait 2383 * for the backend to announce it's features before 2384 * reconnecting, at least we need to know if the backend 2385 * supports indirect descriptors, and how many. 2386 */ 2387 blkif_recover(info); 2388 return; 2389 2390 default: 2391 break; 2392 } 2393 2394 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 2395 __func__, info->xbdev->otherend); 2396 2397 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2398 "sectors", "%llu", §ors, 2399 "info", "%u", &binfo, 2400 "sector-size", "%lu", §or_size, 2401 NULL); 2402 if (err) { 2403 xenbus_dev_fatal(info->xbdev, err, 2404 "reading backend fields at %s", 2405 info->xbdev->otherend); 2406 return; 2407 } 2408 2409 /* 2410 * physcial-sector-size is a newer field, so old backends may not 2411 * provide this. Assume physical sector size to be the same as 2412 * sector_size in that case. 2413 */ 2414 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2415 "physical-sector-size", "%u", &physical_sector_size); 2416 if (err != 1) 2417 physical_sector_size = sector_size; 2418 2419 blkfront_gather_backend_features(info); 2420 for (i = 0; i < info->nr_rings; i++) { 2421 err = blkfront_setup_indirect(&info->rinfo[i]); 2422 if (err) { 2423 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 2424 info->xbdev->otherend); 2425 blkif_free(info, 0); 2426 break; 2427 } 2428 } 2429 2430 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 2431 physical_sector_size); 2432 if (err) { 2433 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 2434 info->xbdev->otherend); 2435 return; 2436 } 2437 2438 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2439 2440 /* Kick pending requests. */ 2441 info->connected = BLKIF_STATE_CONNECTED; 2442 for (i = 0; i < info->nr_rings; i++) 2443 kick_pending_request_queues(&info->rinfo[i]); 2444 2445 device_add_disk(&info->xbdev->dev, info->gd); 2446 2447 info->is_ready = 1; 2448 } 2449 2450 /** 2451 * Callback received when the backend's state changes. 2452 */ 2453 static void blkback_changed(struct xenbus_device *dev, 2454 enum xenbus_state backend_state) 2455 { 2456 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2457 2458 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 2459 2460 switch (backend_state) { 2461 case XenbusStateInitWait: 2462 if (dev->state != XenbusStateInitialising) 2463 break; 2464 if (talk_to_blkback(dev, info)) 2465 break; 2466 case XenbusStateInitialising: 2467 case XenbusStateInitialised: 2468 case XenbusStateReconfiguring: 2469 case XenbusStateReconfigured: 2470 case XenbusStateUnknown: 2471 break; 2472 2473 case XenbusStateConnected: 2474 /* 2475 * talk_to_blkback sets state to XenbusStateInitialised 2476 * and blkfront_connect sets it to XenbusStateConnected 2477 * (if connection went OK). 2478 * 2479 * If the backend (or toolstack) decides to poke at backend 2480 * state (and re-trigger the watch by setting the state repeatedly 2481 * to XenbusStateConnected (4)) we need to deal with this. 2482 * This is allowed as this is used to communicate to the guest 2483 * that the size of disk has changed! 2484 */ 2485 if ((dev->state != XenbusStateInitialised) && 2486 (dev->state != XenbusStateConnected)) { 2487 if (talk_to_blkback(dev, info)) 2488 break; 2489 } 2490 2491 blkfront_connect(info); 2492 break; 2493 2494 case XenbusStateClosed: 2495 if (dev->state == XenbusStateClosed) 2496 break; 2497 /* Missed the backend's Closing state -- fallthrough */ 2498 case XenbusStateClosing: 2499 if (info) 2500 blkfront_closing(info); 2501 break; 2502 } 2503 } 2504 2505 static int blkfront_remove(struct xenbus_device *xbdev) 2506 { 2507 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 2508 struct block_device *bdev = NULL; 2509 struct gendisk *disk; 2510 2511 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 2512 2513 blkif_free(info, 0); 2514 2515 mutex_lock(&info->mutex); 2516 2517 disk = info->gd; 2518 if (disk) 2519 bdev = bdget_disk(disk, 0); 2520 2521 info->xbdev = NULL; 2522 mutex_unlock(&info->mutex); 2523 2524 if (!bdev) { 2525 kfree(info); 2526 return 0; 2527 } 2528 2529 /* 2530 * The xbdev was removed before we reached the Closed 2531 * state. See if it's safe to remove the disk. If the bdev 2532 * isn't closed yet, we let release take care of it. 2533 */ 2534 2535 mutex_lock(&bdev->bd_mutex); 2536 info = disk->private_data; 2537 2538 dev_warn(disk_to_dev(disk), 2539 "%s was hot-unplugged, %d stale handles\n", 2540 xbdev->nodename, bdev->bd_openers); 2541 2542 if (info && !bdev->bd_openers) { 2543 xlvbd_release_gendisk(info); 2544 disk->private_data = NULL; 2545 kfree(info); 2546 } 2547 2548 mutex_unlock(&bdev->bd_mutex); 2549 bdput(bdev); 2550 2551 return 0; 2552 } 2553 2554 static int blkfront_is_ready(struct xenbus_device *dev) 2555 { 2556 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2557 2558 return info->is_ready && info->xbdev; 2559 } 2560 2561 static int blkif_open(struct block_device *bdev, fmode_t mode) 2562 { 2563 struct gendisk *disk = bdev->bd_disk; 2564 struct blkfront_info *info; 2565 int err = 0; 2566 2567 mutex_lock(&blkfront_mutex); 2568 2569 info = disk->private_data; 2570 if (!info) { 2571 /* xbdev gone */ 2572 err = -ERESTARTSYS; 2573 goto out; 2574 } 2575 2576 mutex_lock(&info->mutex); 2577 2578 if (!info->gd) 2579 /* xbdev is closed */ 2580 err = -ERESTARTSYS; 2581 2582 mutex_unlock(&info->mutex); 2583 2584 out: 2585 mutex_unlock(&blkfront_mutex); 2586 return err; 2587 } 2588 2589 static void blkif_release(struct gendisk *disk, fmode_t mode) 2590 { 2591 struct blkfront_info *info = disk->private_data; 2592 struct block_device *bdev; 2593 struct xenbus_device *xbdev; 2594 2595 mutex_lock(&blkfront_mutex); 2596 2597 bdev = bdget_disk(disk, 0); 2598 2599 if (!bdev) { 2600 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2601 goto out_mutex; 2602 } 2603 if (bdev->bd_openers) 2604 goto out; 2605 2606 /* 2607 * Check if we have been instructed to close. We will have 2608 * deferred this request, because the bdev was still open. 2609 */ 2610 2611 mutex_lock(&info->mutex); 2612 xbdev = info->xbdev; 2613 2614 if (xbdev && xbdev->state == XenbusStateClosing) { 2615 /* pending switch to state closed */ 2616 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2617 xlvbd_release_gendisk(info); 2618 xenbus_frontend_closed(info->xbdev); 2619 } 2620 2621 mutex_unlock(&info->mutex); 2622 2623 if (!xbdev) { 2624 /* sudden device removal */ 2625 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2626 xlvbd_release_gendisk(info); 2627 disk->private_data = NULL; 2628 kfree(info); 2629 } 2630 2631 out: 2632 bdput(bdev); 2633 out_mutex: 2634 mutex_unlock(&blkfront_mutex); 2635 } 2636 2637 static const struct block_device_operations xlvbd_block_fops = 2638 { 2639 .owner = THIS_MODULE, 2640 .open = blkif_open, 2641 .release = blkif_release, 2642 .getgeo = blkif_getgeo, 2643 .ioctl = blkif_ioctl, 2644 }; 2645 2646 2647 static const struct xenbus_device_id blkfront_ids[] = { 2648 { "vbd" }, 2649 { "" } 2650 }; 2651 2652 static struct xenbus_driver blkfront_driver = { 2653 .ids = blkfront_ids, 2654 .probe = blkfront_probe, 2655 .remove = blkfront_remove, 2656 .resume = blkfront_resume, 2657 .otherend_changed = blkback_changed, 2658 .is_ready = blkfront_is_ready, 2659 }; 2660 2661 static int __init xlblk_init(void) 2662 { 2663 int ret; 2664 int nr_cpus = num_online_cpus(); 2665 2666 if (!xen_domain()) 2667 return -ENODEV; 2668 2669 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { 2670 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 2671 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); 2672 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 2673 } 2674 2675 if (xen_blkif_max_queues > nr_cpus) { 2676 pr_info("Invalid max_queues (%d), will use default max: %d.\n", 2677 xen_blkif_max_queues, nr_cpus); 2678 xen_blkif_max_queues = nr_cpus; 2679 } 2680 2681 if (!xen_has_pv_disk_devices()) 2682 return -ENODEV; 2683 2684 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2685 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2686 XENVBD_MAJOR, DEV_NAME); 2687 return -ENODEV; 2688 } 2689 2690 ret = xenbus_register_frontend(&blkfront_driver); 2691 if (ret) { 2692 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2693 return ret; 2694 } 2695 2696 return 0; 2697 } 2698 module_init(xlblk_init); 2699 2700 2701 static void __exit xlblk_exit(void) 2702 { 2703 xenbus_unregister_driver(&blkfront_driver); 2704 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2705 kfree(minors); 2706 } 2707 module_exit(xlblk_exit); 2708 2709 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2710 MODULE_LICENSE("GPL"); 2711 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2712 MODULE_ALIAS("xen:vbd"); 2713 MODULE_ALIAS("xenblk"); 2714