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