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