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, xen_blkif_max_segments, int, S_IRUGO); 129 MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)"); 130 131 static unsigned int xen_blkif_max_queues = 4; 132 module_param_named(max_queues, xen_blkif_max_queues, uint, S_IRUGO); 133 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk"); 134 135 /* 136 * Maximum order of pages to be used for the shared ring between front and 137 * backend, 4KB page granularity is used. 138 */ 139 static unsigned int xen_blkif_max_ring_order; 140 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO); 141 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring"); 142 143 #define BLK_RING_SIZE(info) \ 144 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages) 145 146 #define BLK_MAX_RING_SIZE \ 147 __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS) 148 149 /* 150 * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19 151 * characters are enough. Define to 20 to keep consistent with backend. 152 */ 153 #define RINGREF_NAME_LEN (20) 154 /* 155 * queue-%u would take 7 + 10(UINT_MAX) = 17 characters. 156 */ 157 #define QUEUE_NAME_LEN (17) 158 159 /* 160 * Per-ring info. 161 * Every blkfront device can associate with one or more blkfront_ring_info, 162 * depending on how many hardware queues/rings to be used. 163 */ 164 struct blkfront_ring_info { 165 /* Lock to protect data in every ring buffer. */ 166 spinlock_t ring_lock; 167 struct blkif_front_ring ring; 168 unsigned int ring_ref[XENBUS_MAX_RING_GRANTS]; 169 unsigned int evtchn, irq; 170 struct work_struct work; 171 struct gnttab_free_callback callback; 172 struct blk_shadow shadow[BLK_MAX_RING_SIZE]; 173 struct list_head indirect_pages; 174 struct list_head grants; 175 unsigned int persistent_gnts_c; 176 unsigned long shadow_free; 177 struct blkfront_info *dev_info; 178 }; 179 180 /* 181 * We have one of these per vbd, whether ide, scsi or 'other'. They 182 * hang in private_data off the gendisk structure. We may end up 183 * putting all kinds of interesting stuff here :-) 184 */ 185 struct blkfront_info 186 { 187 struct mutex mutex; 188 struct xenbus_device *xbdev; 189 struct gendisk *gd; 190 int vdevice; 191 blkif_vdev_t handle; 192 enum blkif_state connected; 193 /* Number of pages per ring buffer. */ 194 unsigned int nr_ring_pages; 195 struct request_queue *rq; 196 unsigned int feature_flush; 197 unsigned int feature_discard:1; 198 unsigned int feature_secdiscard:1; 199 unsigned int discard_granularity; 200 unsigned int discard_alignment; 201 unsigned int feature_persistent:1; 202 /* Number of 4KB segments handled */ 203 unsigned int max_indirect_segments; 204 int is_ready; 205 struct blk_mq_tag_set tag_set; 206 struct blkfront_ring_info *rinfo; 207 unsigned int nr_rings; 208 }; 209 210 static unsigned int nr_minors; 211 static unsigned long *minors; 212 static DEFINE_SPINLOCK(minor_lock); 213 214 #define GRANT_INVALID_REF 0 215 216 #define PARTS_PER_DISK 16 217 #define PARTS_PER_EXT_DISK 256 218 219 #define BLKIF_MAJOR(dev) ((dev)>>8) 220 #define BLKIF_MINOR(dev) ((dev) & 0xff) 221 222 #define EXT_SHIFT 28 223 #define EXTENDED (1<<EXT_SHIFT) 224 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 225 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 226 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 227 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 228 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 229 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 230 231 #define DEV_NAME "xvd" /* name in /dev */ 232 233 /* 234 * Grants are always the same size as a Xen page (i.e 4KB). 235 * A physical segment is always the same size as a Linux page. 236 * Number of grants per physical segment 237 */ 238 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE) 239 240 #define GRANTS_PER_INDIRECT_FRAME \ 241 (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment)) 242 243 #define PSEGS_PER_INDIRECT_FRAME \ 244 (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS) 245 246 #define INDIRECT_GREFS(_grants) \ 247 DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME) 248 249 #define GREFS(_psegs) ((_psegs) * GRANTS_PER_PSEG) 250 251 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo); 252 static void blkfront_gather_backend_features(struct blkfront_info *info); 253 254 static int get_id_from_freelist(struct blkfront_ring_info *rinfo) 255 { 256 unsigned long free = rinfo->shadow_free; 257 258 BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info)); 259 rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id; 260 rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 261 return free; 262 } 263 264 static int add_id_to_freelist(struct blkfront_ring_info *rinfo, 265 unsigned long id) 266 { 267 if (rinfo->shadow[id].req.u.rw.id != id) 268 return -EINVAL; 269 if (rinfo->shadow[id].request == NULL) 270 return -EINVAL; 271 rinfo->shadow[id].req.u.rw.id = rinfo->shadow_free; 272 rinfo->shadow[id].request = NULL; 273 rinfo->shadow_free = id; 274 return 0; 275 } 276 277 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num) 278 { 279 struct blkfront_info *info = rinfo->dev_info; 280 struct page *granted_page; 281 struct grant *gnt_list_entry, *n; 282 int i = 0; 283 284 while (i < num) { 285 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 286 if (!gnt_list_entry) 287 goto out_of_memory; 288 289 if (info->feature_persistent) { 290 granted_page = alloc_page(GFP_NOIO); 291 if (!granted_page) { 292 kfree(gnt_list_entry); 293 goto out_of_memory; 294 } 295 gnt_list_entry->page = granted_page; 296 } 297 298 gnt_list_entry->gref = GRANT_INVALID_REF; 299 list_add(&gnt_list_entry->node, &rinfo->grants); 300 i++; 301 } 302 303 return 0; 304 305 out_of_memory: 306 list_for_each_entry_safe(gnt_list_entry, n, 307 &rinfo->grants, node) { 308 list_del(&gnt_list_entry->node); 309 if (info->feature_persistent) 310 __free_page(gnt_list_entry->page); 311 kfree(gnt_list_entry); 312 i--; 313 } 314 BUG_ON(i != 0); 315 return -ENOMEM; 316 } 317 318 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo) 319 { 320 struct grant *gnt_list_entry; 321 322 BUG_ON(list_empty(&rinfo->grants)); 323 gnt_list_entry = list_first_entry(&rinfo->grants, struct grant, 324 node); 325 list_del(&gnt_list_entry->node); 326 327 if (gnt_list_entry->gref != GRANT_INVALID_REF) 328 rinfo->persistent_gnts_c--; 329 330 return gnt_list_entry; 331 } 332 333 static inline void grant_foreign_access(const struct grant *gnt_list_entry, 334 const struct blkfront_info *info) 335 { 336 gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref, 337 info->xbdev->otherend_id, 338 gnt_list_entry->page, 339 0); 340 } 341 342 static struct grant *get_grant(grant_ref_t *gref_head, 343 unsigned long gfn, 344 struct blkfront_ring_info *rinfo) 345 { 346 struct grant *gnt_list_entry = get_free_grant(rinfo); 347 struct blkfront_info *info = rinfo->dev_info; 348 349 if (gnt_list_entry->gref != GRANT_INVALID_REF) 350 return gnt_list_entry; 351 352 /* Assign a gref to this page */ 353 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 354 BUG_ON(gnt_list_entry->gref == -ENOSPC); 355 if (info->feature_persistent) 356 grant_foreign_access(gnt_list_entry, info); 357 else { 358 /* Grant access to the GFN passed by the caller */ 359 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 360 info->xbdev->otherend_id, 361 gfn, 0); 362 } 363 364 return gnt_list_entry; 365 } 366 367 static struct grant *get_indirect_grant(grant_ref_t *gref_head, 368 struct blkfront_ring_info *rinfo) 369 { 370 struct grant *gnt_list_entry = get_free_grant(rinfo); 371 struct blkfront_info *info = rinfo->dev_info; 372 373 if (gnt_list_entry->gref != GRANT_INVALID_REF) 374 return gnt_list_entry; 375 376 /* Assign a gref to this page */ 377 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 378 BUG_ON(gnt_list_entry->gref == -ENOSPC); 379 if (!info->feature_persistent) { 380 struct page *indirect_page; 381 382 /* Fetch a pre-allocated page to use for indirect grefs */ 383 BUG_ON(list_empty(&rinfo->indirect_pages)); 384 indirect_page = list_first_entry(&rinfo->indirect_pages, 385 struct page, lru); 386 list_del(&indirect_page->lru); 387 gnt_list_entry->page = indirect_page; 388 } 389 grant_foreign_access(gnt_list_entry, info); 390 391 return gnt_list_entry; 392 } 393 394 static const char *op_name(int op) 395 { 396 static const char *const names[] = { 397 [BLKIF_OP_READ] = "read", 398 [BLKIF_OP_WRITE] = "write", 399 [BLKIF_OP_WRITE_BARRIER] = "barrier", 400 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 401 [BLKIF_OP_DISCARD] = "discard" }; 402 403 if (op < 0 || op >= ARRAY_SIZE(names)) 404 return "unknown"; 405 406 if (!names[op]) 407 return "reserved"; 408 409 return names[op]; 410 } 411 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 412 { 413 unsigned int end = minor + nr; 414 int rc; 415 416 if (end > nr_minors) { 417 unsigned long *bitmap, *old; 418 419 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 420 GFP_KERNEL); 421 if (bitmap == NULL) 422 return -ENOMEM; 423 424 spin_lock(&minor_lock); 425 if (end > nr_minors) { 426 old = minors; 427 memcpy(bitmap, minors, 428 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 429 minors = bitmap; 430 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 431 } else 432 old = bitmap; 433 spin_unlock(&minor_lock); 434 kfree(old); 435 } 436 437 spin_lock(&minor_lock); 438 if (find_next_bit(minors, end, minor) >= end) { 439 bitmap_set(minors, minor, nr); 440 rc = 0; 441 } else 442 rc = -EBUSY; 443 spin_unlock(&minor_lock); 444 445 return rc; 446 } 447 448 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 449 { 450 unsigned int end = minor + nr; 451 452 BUG_ON(end > nr_minors); 453 spin_lock(&minor_lock); 454 bitmap_clear(minors, minor, nr); 455 spin_unlock(&minor_lock); 456 } 457 458 static void blkif_restart_queue_callback(void *arg) 459 { 460 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg; 461 schedule_work(&rinfo->work); 462 } 463 464 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 465 { 466 /* We don't have real geometry info, but let's at least return 467 values consistent with the size of the device */ 468 sector_t nsect = get_capacity(bd->bd_disk); 469 sector_t cylinders = nsect; 470 471 hg->heads = 0xff; 472 hg->sectors = 0x3f; 473 sector_div(cylinders, hg->heads * hg->sectors); 474 hg->cylinders = cylinders; 475 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 476 hg->cylinders = 0xffff; 477 return 0; 478 } 479 480 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 481 unsigned command, unsigned long argument) 482 { 483 struct blkfront_info *info = bdev->bd_disk->private_data; 484 int i; 485 486 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 487 command, (long)argument); 488 489 switch (command) { 490 case CDROMMULTISESSION: 491 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 492 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 493 if (put_user(0, (char __user *)(argument + i))) 494 return -EFAULT; 495 return 0; 496 497 case CDROM_GET_CAPABILITY: { 498 struct gendisk *gd = info->gd; 499 if (gd->flags & GENHD_FL_CD) 500 return 0; 501 return -EINVAL; 502 } 503 504 default: 505 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 506 command);*/ 507 return -EINVAL; /* same return as native Linux */ 508 } 509 510 return 0; 511 } 512 513 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo, 514 struct request *req, 515 struct blkif_request **ring_req) 516 { 517 unsigned long id; 518 519 *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt); 520 rinfo->ring.req_prod_pvt++; 521 522 id = get_id_from_freelist(rinfo); 523 rinfo->shadow[id].request = req; 524 rinfo->shadow[id].status = REQ_WAITING; 525 rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID; 526 527 (*ring_req)->u.rw.id = id; 528 529 return id; 530 } 531 532 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo) 533 { 534 struct blkfront_info *info = rinfo->dev_info; 535 struct blkif_request *ring_req; 536 unsigned long id; 537 538 /* Fill out a communications ring structure. */ 539 id = blkif_ring_get_request(rinfo, req, &ring_req); 540 541 ring_req->operation = BLKIF_OP_DISCARD; 542 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 543 ring_req->u.discard.id = id; 544 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 545 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) 546 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 547 else 548 ring_req->u.discard.flag = 0; 549 550 /* Keep a private copy so we can reissue requests when recovering. */ 551 rinfo->shadow[id].req = *ring_req; 552 553 return 0; 554 } 555 556 struct setup_rw_req { 557 unsigned int grant_idx; 558 struct blkif_request_segment *segments; 559 struct blkfront_ring_info *rinfo; 560 struct blkif_request *ring_req; 561 grant_ref_t gref_head; 562 unsigned int id; 563 /* Only used when persistent grant is used and it's a read request */ 564 bool need_copy; 565 unsigned int bvec_off; 566 char *bvec_data; 567 568 bool require_extra_req; 569 struct blkif_request *extra_ring_req; 570 }; 571 572 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset, 573 unsigned int len, void *data) 574 { 575 struct setup_rw_req *setup = data; 576 int n, ref; 577 struct grant *gnt_list_entry; 578 unsigned int fsect, lsect; 579 /* Convenient aliases */ 580 unsigned int grant_idx = setup->grant_idx; 581 struct blkif_request *ring_req = setup->ring_req; 582 struct blkfront_ring_info *rinfo = setup->rinfo; 583 /* 584 * We always use the shadow of the first request to store the list 585 * of grant associated to the block I/O request. This made the 586 * completion more easy to handle even if the block I/O request is 587 * split. 588 */ 589 struct blk_shadow *shadow = &rinfo->shadow[setup->id]; 590 591 if (unlikely(setup->require_extra_req && 592 grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 593 /* 594 * We are using the second request, setup grant_idx 595 * to be the index of the segment array. 596 */ 597 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST; 598 ring_req = setup->extra_ring_req; 599 } 600 601 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 602 (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) { 603 if (setup->segments) 604 kunmap_atomic(setup->segments); 605 606 n = grant_idx / GRANTS_PER_INDIRECT_FRAME; 607 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo); 608 shadow->indirect_grants[n] = gnt_list_entry; 609 setup->segments = kmap_atomic(gnt_list_entry->page); 610 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 611 } 612 613 gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo); 614 ref = gnt_list_entry->gref; 615 /* 616 * All the grants are stored in the shadow of the first 617 * request. Therefore we have to use the global index. 618 */ 619 shadow->grants_used[setup->grant_idx] = gnt_list_entry; 620 621 if (setup->need_copy) { 622 void *shared_data; 623 624 shared_data = kmap_atomic(gnt_list_entry->page); 625 /* 626 * this does not wipe data stored outside the 627 * range sg->offset..sg->offset+sg->length. 628 * Therefore, blkback *could* see data from 629 * previous requests. This is OK as long as 630 * persistent grants are shared with just one 631 * domain. It may need refactoring if this 632 * changes 633 */ 634 memcpy(shared_data + offset, 635 setup->bvec_data + setup->bvec_off, 636 len); 637 638 kunmap_atomic(shared_data); 639 setup->bvec_off += len; 640 } 641 642 fsect = offset >> 9; 643 lsect = fsect + (len >> 9) - 1; 644 if (ring_req->operation != BLKIF_OP_INDIRECT) { 645 ring_req->u.rw.seg[grant_idx] = 646 (struct blkif_request_segment) { 647 .gref = ref, 648 .first_sect = fsect, 649 .last_sect = lsect }; 650 } else { 651 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] = 652 (struct blkif_request_segment) { 653 .gref = ref, 654 .first_sect = fsect, 655 .last_sect = lsect }; 656 } 657 658 (setup->grant_idx)++; 659 } 660 661 static void blkif_setup_extra_req(struct blkif_request *first, 662 struct blkif_request *second) 663 { 664 uint16_t nr_segments = first->u.rw.nr_segments; 665 666 /* 667 * The second request is only present when the first request uses 668 * all its segments. It's always the continuity of the first one. 669 */ 670 first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST; 671 672 second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST; 673 second->u.rw.sector_number = first->u.rw.sector_number + 674 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512; 675 676 second->u.rw.handle = first->u.rw.handle; 677 second->operation = first->operation; 678 } 679 680 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo) 681 { 682 struct blkfront_info *info = rinfo->dev_info; 683 struct blkif_request *ring_req, *extra_ring_req = NULL; 684 unsigned long id, extra_id = NO_ASSOCIATED_ID; 685 bool require_extra_req = false; 686 int i; 687 struct setup_rw_req setup = { 688 .grant_idx = 0, 689 .segments = NULL, 690 .rinfo = rinfo, 691 .need_copy = rq_data_dir(req) && info->feature_persistent, 692 }; 693 694 /* 695 * Used to store if we are able to queue the request by just using 696 * existing persistent grants, or if we have to get new grants, 697 * as there are not sufficiently many free. 698 */ 699 struct scatterlist *sg; 700 int num_sg, max_grefs, num_grant; 701 702 max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG; 703 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 704 /* 705 * If we are using indirect segments we need to account 706 * for the indirect grefs used in the request. 707 */ 708 max_grefs += INDIRECT_GREFS(max_grefs); 709 710 /* 711 * We have to reserve 'max_grefs' grants because persistent 712 * grants are shared by all rings. 713 */ 714 if (max_grefs > 0) 715 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) { 716 gnttab_request_free_callback( 717 &rinfo->callback, 718 blkif_restart_queue_callback, 719 rinfo, 720 max_grefs); 721 return 1; 722 } 723 724 /* Fill out a communications ring structure. */ 725 id = blkif_ring_get_request(rinfo, req, &ring_req); 726 727 num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg); 728 num_grant = 0; 729 /* Calculate the number of grant used */ 730 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) 731 num_grant += gnttab_count_grant(sg->offset, sg->length); 732 733 require_extra_req = info->max_indirect_segments == 0 && 734 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST; 735 BUG_ON(!HAS_EXTRA_REQ && require_extra_req); 736 737 rinfo->shadow[id].num_sg = num_sg; 738 if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST && 739 likely(!require_extra_req)) { 740 /* 741 * The indirect operation can only be a BLKIF_OP_READ or 742 * BLKIF_OP_WRITE 743 */ 744 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA)); 745 ring_req->operation = BLKIF_OP_INDIRECT; 746 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 747 BLKIF_OP_WRITE : BLKIF_OP_READ; 748 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 749 ring_req->u.indirect.handle = info->handle; 750 ring_req->u.indirect.nr_segments = num_grant; 751 } else { 752 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 753 ring_req->u.rw.handle = info->handle; 754 ring_req->operation = rq_data_dir(req) ? 755 BLKIF_OP_WRITE : BLKIF_OP_READ; 756 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { 757 /* 758 * Ideally we can do an unordered flush-to-disk. 759 * In case the backend onlysupports barriers, use that. 760 * A barrier request a superset of FUA, so we can 761 * implement it the same way. (It's also a FLUSH+FUA, 762 * since it is guaranteed ordered WRT previous writes.) 763 */ 764 switch (info->feature_flush & 765 ((REQ_FLUSH|REQ_FUA))) { 766 case REQ_FLUSH|REQ_FUA: 767 ring_req->operation = 768 BLKIF_OP_WRITE_BARRIER; 769 break; 770 case REQ_FLUSH: 771 ring_req->operation = 772 BLKIF_OP_FLUSH_DISKCACHE; 773 break; 774 default: 775 ring_req->operation = 0; 776 } 777 } 778 ring_req->u.rw.nr_segments = num_grant; 779 if (unlikely(require_extra_req)) { 780 extra_id = blkif_ring_get_request(rinfo, req, 781 &extra_ring_req); 782 /* 783 * Only the first request contains the scatter-gather 784 * list. 785 */ 786 rinfo->shadow[extra_id].num_sg = 0; 787 788 blkif_setup_extra_req(ring_req, extra_ring_req); 789 790 /* Link the 2 requests together */ 791 rinfo->shadow[extra_id].associated_id = id; 792 rinfo->shadow[id].associated_id = extra_id; 793 } 794 } 795 796 setup.ring_req = ring_req; 797 setup.id = id; 798 799 setup.require_extra_req = require_extra_req; 800 if (unlikely(require_extra_req)) 801 setup.extra_ring_req = extra_ring_req; 802 803 for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) { 804 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 805 806 if (setup.need_copy) { 807 setup.bvec_off = sg->offset; 808 setup.bvec_data = kmap_atomic(sg_page(sg)); 809 } 810 811 gnttab_foreach_grant_in_range(sg_page(sg), 812 sg->offset, 813 sg->length, 814 blkif_setup_rw_req_grant, 815 &setup); 816 817 if (setup.need_copy) 818 kunmap_atomic(setup.bvec_data); 819 } 820 if (setup.segments) 821 kunmap_atomic(setup.segments); 822 823 /* Keep a private copy so we can reissue requests when recovering. */ 824 rinfo->shadow[id].req = *ring_req; 825 if (unlikely(require_extra_req)) 826 rinfo->shadow[extra_id].req = *extra_ring_req; 827 828 if (max_grefs > 0) 829 gnttab_free_grant_references(setup.gref_head); 830 831 return 0; 832 } 833 834 /* 835 * Generate a Xen blkfront IO request from a blk layer request. Reads 836 * and writes are handled as expected. 837 * 838 * @req: a request struct 839 */ 840 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo) 841 { 842 if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED)) 843 return 1; 844 845 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) 846 return blkif_queue_discard_req(req, rinfo); 847 else 848 return blkif_queue_rw_req(req, rinfo); 849 } 850 851 static inline void flush_requests(struct blkfront_ring_info *rinfo) 852 { 853 int notify; 854 855 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify); 856 857 if (notify) 858 notify_remote_via_irq(rinfo->irq); 859 } 860 861 static inline bool blkif_request_flush_invalid(struct request *req, 862 struct blkfront_info *info) 863 { 864 return ((req->cmd_type != REQ_TYPE_FS) || 865 ((req->cmd_flags & REQ_FLUSH) && 866 !(info->feature_flush & REQ_FLUSH)) || 867 ((req->cmd_flags & REQ_FUA) && 868 !(info->feature_flush & REQ_FUA))); 869 } 870 871 static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx, 872 const struct blk_mq_queue_data *qd) 873 { 874 unsigned long flags; 875 struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)hctx->driver_data; 876 877 blk_mq_start_request(qd->rq); 878 spin_lock_irqsave(&rinfo->ring_lock, flags); 879 if (RING_FULL(&rinfo->ring)) 880 goto out_busy; 881 882 if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info)) 883 goto out_err; 884 885 if (blkif_queue_request(qd->rq, rinfo)) 886 goto out_busy; 887 888 flush_requests(rinfo); 889 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 890 return BLK_MQ_RQ_QUEUE_OK; 891 892 out_err: 893 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 894 return BLK_MQ_RQ_QUEUE_ERROR; 895 896 out_busy: 897 spin_unlock_irqrestore(&rinfo->ring_lock, flags); 898 blk_mq_stop_hw_queue(hctx); 899 return BLK_MQ_RQ_QUEUE_BUSY; 900 } 901 902 static int blk_mq_init_hctx(struct blk_mq_hw_ctx *hctx, void *data, 903 unsigned int index) 904 { 905 struct blkfront_info *info = (struct blkfront_info *)data; 906 907 BUG_ON(info->nr_rings <= index); 908 hctx->driver_data = &info->rinfo[index]; 909 return 0; 910 } 911 912 static struct blk_mq_ops blkfront_mq_ops = { 913 .queue_rq = blkif_queue_rq, 914 .map_queue = blk_mq_map_queue, 915 .init_hctx = blk_mq_init_hctx, 916 }; 917 918 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, 919 unsigned int physical_sector_size, 920 unsigned int segments) 921 { 922 struct request_queue *rq; 923 struct blkfront_info *info = gd->private_data; 924 925 memset(&info->tag_set, 0, sizeof(info->tag_set)); 926 info->tag_set.ops = &blkfront_mq_ops; 927 info->tag_set.nr_hw_queues = info->nr_rings; 928 if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) { 929 /* 930 * When indirect descriptior is not supported, the I/O request 931 * will be split between multiple request in the ring. 932 * To avoid problems when sending the request, divide by 933 * 2 the depth of the queue. 934 */ 935 info->tag_set.queue_depth = BLK_RING_SIZE(info) / 2; 936 } else 937 info->tag_set.queue_depth = BLK_RING_SIZE(info); 938 info->tag_set.numa_node = NUMA_NO_NODE; 939 info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE; 940 info->tag_set.cmd_size = 0; 941 info->tag_set.driver_data = info; 942 943 if (blk_mq_alloc_tag_set(&info->tag_set)) 944 return -EINVAL; 945 rq = blk_mq_init_queue(&info->tag_set); 946 if (IS_ERR(rq)) { 947 blk_mq_free_tag_set(&info->tag_set); 948 return PTR_ERR(rq); 949 } 950 951 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 952 953 if (info->feature_discard) { 954 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); 955 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 956 rq->limits.discard_granularity = info->discard_granularity; 957 rq->limits.discard_alignment = info->discard_alignment; 958 if (info->feature_secdiscard) 959 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq); 960 } 961 962 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 963 blk_queue_logical_block_size(rq, sector_size); 964 blk_queue_physical_block_size(rq, physical_sector_size); 965 blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512); 966 967 /* Each segment in a request is up to an aligned page in size. */ 968 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 969 blk_queue_max_segment_size(rq, PAGE_SIZE); 970 971 /* Ensure a merged request will fit in a single I/O ring slot. */ 972 blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG); 973 974 /* Make sure buffer addresses are sector-aligned. */ 975 blk_queue_dma_alignment(rq, 511); 976 977 /* Make sure we don't use bounce buffers. */ 978 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); 979 980 gd->queue = rq; 981 982 return 0; 983 } 984 985 static const char *flush_info(unsigned int feature_flush) 986 { 987 switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) { 988 case REQ_FLUSH|REQ_FUA: 989 return "barrier: enabled;"; 990 case REQ_FLUSH: 991 return "flush diskcache: enabled;"; 992 default: 993 return "barrier or flush: disabled;"; 994 } 995 } 996 997 static void xlvbd_flush(struct blkfront_info *info) 998 { 999 blk_queue_flush(info->rq, info->feature_flush); 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 struct blk_shadow *copy; 2009 int rc; 2010 struct bio *bio, *cloned_bio; 2011 struct bio_list bio_list, merge_bio; 2012 unsigned int segs, offset; 2013 int pending, size; 2014 struct split_bio *split_bio; 2015 struct list_head requests; 2016 2017 blkfront_gather_backend_features(info); 2018 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 2019 blk_queue_max_segments(info->rq, segs); 2020 bio_list_init(&bio_list); 2021 INIT_LIST_HEAD(&requests); 2022 2023 for (r_index = 0; r_index < info->nr_rings; r_index++) { 2024 struct blkfront_ring_info *rinfo; 2025 2026 rinfo = &info->rinfo[r_index]; 2027 /* Stage 1: Make a safe copy of the shadow state. */ 2028 copy = kmemdup(rinfo->shadow, sizeof(rinfo->shadow), 2029 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); 2030 if (!copy) 2031 return -ENOMEM; 2032 2033 /* Stage 2: Set up free list. */ 2034 memset(&rinfo->shadow, 0, sizeof(rinfo->shadow)); 2035 for (i = 0; i < BLK_RING_SIZE(info); i++) 2036 rinfo->shadow[i].req.u.rw.id = i+1; 2037 rinfo->shadow_free = rinfo->ring.req_prod_pvt; 2038 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff; 2039 2040 rc = blkfront_setup_indirect(rinfo); 2041 if (rc) { 2042 kfree(copy); 2043 return rc; 2044 } 2045 2046 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2047 /* Not in use? */ 2048 if (!copy[i].request) 2049 continue; 2050 2051 /* 2052 * Get the bios in the request so we can re-queue them. 2053 */ 2054 if (copy[i].request->cmd_flags & 2055 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 2056 /* 2057 * Flush operations don't contain bios, so 2058 * we need to requeue the whole request 2059 */ 2060 list_add(©[i].request->queuelist, &requests); 2061 continue; 2062 } 2063 merge_bio.head = copy[i].request->bio; 2064 merge_bio.tail = copy[i].request->biotail; 2065 bio_list_merge(&bio_list, &merge_bio); 2066 copy[i].request->bio = NULL; 2067 blk_end_request_all(copy[i].request, 0); 2068 } 2069 2070 kfree(copy); 2071 } 2072 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2073 2074 /* Now safe for us to use the shared ring */ 2075 info->connected = BLKIF_STATE_CONNECTED; 2076 2077 for (r_index = 0; r_index < info->nr_rings; r_index++) { 2078 struct blkfront_ring_info *rinfo; 2079 2080 rinfo = &info->rinfo[r_index]; 2081 /* Kick any other new requests queued since we resumed */ 2082 kick_pending_request_queues(rinfo); 2083 } 2084 2085 list_for_each_entry_safe(req, n, &requests, queuelist) { 2086 /* Requeue pending requests (flush or discard) */ 2087 list_del_init(&req->queuelist); 2088 BUG_ON(req->nr_phys_segments > segs); 2089 blk_mq_requeue_request(req); 2090 } 2091 blk_mq_kick_requeue_list(info->rq); 2092 2093 while ((bio = bio_list_pop(&bio_list)) != NULL) { 2094 /* Traverse the list of pending bios and re-queue them */ 2095 if (bio_segments(bio) > segs) { 2096 /* 2097 * This bio has more segments than what we can 2098 * handle, we have to split it. 2099 */ 2100 pending = (bio_segments(bio) + segs - 1) / segs; 2101 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO); 2102 BUG_ON(split_bio == NULL); 2103 atomic_set(&split_bio->pending, pending); 2104 split_bio->bio = bio; 2105 for (i = 0; i < pending; i++) { 2106 offset = (i * segs * XEN_PAGE_SIZE) >> 9; 2107 size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9, 2108 (unsigned int)bio_sectors(bio) - offset); 2109 cloned_bio = bio_clone(bio, GFP_NOIO); 2110 BUG_ON(cloned_bio == NULL); 2111 bio_trim(cloned_bio, offset, size); 2112 cloned_bio->bi_private = split_bio; 2113 cloned_bio->bi_end_io = split_bio_end; 2114 submit_bio(cloned_bio->bi_rw, cloned_bio); 2115 } 2116 /* 2117 * Now we have to wait for all those smaller bios to 2118 * end, so we can also end the "parent" bio. 2119 */ 2120 continue; 2121 } 2122 /* We don't need to split this bio */ 2123 submit_bio(bio->bi_rw, bio); 2124 } 2125 2126 return 0; 2127 } 2128 2129 /** 2130 * We are reconnecting to the backend, due to a suspend/resume, or a backend 2131 * driver restart. We tear down our blkif structure and recreate it, but 2132 * leave the device-layer structures intact so that this is transparent to the 2133 * rest of the kernel. 2134 */ 2135 static int blkfront_resume(struct xenbus_device *dev) 2136 { 2137 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2138 int err = 0; 2139 2140 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 2141 2142 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 2143 2144 err = negotiate_mq(info); 2145 if (err) 2146 return err; 2147 2148 err = talk_to_blkback(dev, info); 2149 2150 /* 2151 * We have to wait for the backend to switch to 2152 * connected state, since we want to read which 2153 * features it supports. 2154 */ 2155 2156 return err; 2157 } 2158 2159 static void blkfront_closing(struct blkfront_info *info) 2160 { 2161 struct xenbus_device *xbdev = info->xbdev; 2162 struct block_device *bdev = NULL; 2163 2164 mutex_lock(&info->mutex); 2165 2166 if (xbdev->state == XenbusStateClosing) { 2167 mutex_unlock(&info->mutex); 2168 return; 2169 } 2170 2171 if (info->gd) 2172 bdev = bdget_disk(info->gd, 0); 2173 2174 mutex_unlock(&info->mutex); 2175 2176 if (!bdev) { 2177 xenbus_frontend_closed(xbdev); 2178 return; 2179 } 2180 2181 mutex_lock(&bdev->bd_mutex); 2182 2183 if (bdev->bd_openers) { 2184 xenbus_dev_error(xbdev, -EBUSY, 2185 "Device in use; refusing to close"); 2186 xenbus_switch_state(xbdev, XenbusStateClosing); 2187 } else { 2188 xlvbd_release_gendisk(info); 2189 xenbus_frontend_closed(xbdev); 2190 } 2191 2192 mutex_unlock(&bdev->bd_mutex); 2193 bdput(bdev); 2194 } 2195 2196 static void blkfront_setup_discard(struct blkfront_info *info) 2197 { 2198 int err; 2199 unsigned int discard_granularity; 2200 unsigned int discard_alignment; 2201 unsigned int discard_secure; 2202 2203 info->feature_discard = 1; 2204 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2205 "discard-granularity", "%u", &discard_granularity, 2206 "discard-alignment", "%u", &discard_alignment, 2207 NULL); 2208 if (!err) { 2209 info->discard_granularity = discard_granularity; 2210 info->discard_alignment = discard_alignment; 2211 } 2212 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2213 "discard-secure", "%d", &discard_secure, 2214 NULL); 2215 if (!err) 2216 info->feature_secdiscard = !!discard_secure; 2217 } 2218 2219 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo) 2220 { 2221 unsigned int psegs, grants; 2222 int err, i; 2223 struct blkfront_info *info = rinfo->dev_info; 2224 2225 if (info->max_indirect_segments == 0) { 2226 if (!HAS_EXTRA_REQ) 2227 grants = BLKIF_MAX_SEGMENTS_PER_REQUEST; 2228 else { 2229 /* 2230 * When an extra req is required, the maximum 2231 * grants supported is related to the size of the 2232 * Linux block segment. 2233 */ 2234 grants = GRANTS_PER_PSEG; 2235 } 2236 } 2237 else 2238 grants = info->max_indirect_segments; 2239 psegs = grants / GRANTS_PER_PSEG; 2240 2241 err = fill_grant_buffer(rinfo, 2242 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info)); 2243 if (err) 2244 goto out_of_memory; 2245 2246 if (!info->feature_persistent && info->max_indirect_segments) { 2247 /* 2248 * We are using indirect descriptors but not persistent 2249 * grants, we need to allocate a set of pages that can be 2250 * used for mapping indirect grefs 2251 */ 2252 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info); 2253 2254 BUG_ON(!list_empty(&rinfo->indirect_pages)); 2255 for (i = 0; i < num; i++) { 2256 struct page *indirect_page = alloc_page(GFP_NOIO); 2257 if (!indirect_page) 2258 goto out_of_memory; 2259 list_add(&indirect_page->lru, &rinfo->indirect_pages); 2260 } 2261 } 2262 2263 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2264 rinfo->shadow[i].grants_used = kzalloc( 2265 sizeof(rinfo->shadow[i].grants_used[0]) * grants, 2266 GFP_NOIO); 2267 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO); 2268 if (info->max_indirect_segments) 2269 rinfo->shadow[i].indirect_grants = kzalloc( 2270 sizeof(rinfo->shadow[i].indirect_grants[0]) * 2271 INDIRECT_GREFS(grants), 2272 GFP_NOIO); 2273 if ((rinfo->shadow[i].grants_used == NULL) || 2274 (rinfo->shadow[i].sg == NULL) || 2275 (info->max_indirect_segments && 2276 (rinfo->shadow[i].indirect_grants == NULL))) 2277 goto out_of_memory; 2278 sg_init_table(rinfo->shadow[i].sg, psegs); 2279 } 2280 2281 2282 return 0; 2283 2284 out_of_memory: 2285 for (i = 0; i < BLK_RING_SIZE(info); i++) { 2286 kfree(rinfo->shadow[i].grants_used); 2287 rinfo->shadow[i].grants_used = NULL; 2288 kfree(rinfo->shadow[i].sg); 2289 rinfo->shadow[i].sg = NULL; 2290 kfree(rinfo->shadow[i].indirect_grants); 2291 rinfo->shadow[i].indirect_grants = NULL; 2292 } 2293 if (!list_empty(&rinfo->indirect_pages)) { 2294 struct page *indirect_page, *n; 2295 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) { 2296 list_del(&indirect_page->lru); 2297 __free_page(indirect_page); 2298 } 2299 } 2300 return -ENOMEM; 2301 } 2302 2303 /* 2304 * Gather all backend feature-* 2305 */ 2306 static void blkfront_gather_backend_features(struct blkfront_info *info) 2307 { 2308 int err; 2309 int barrier, flush, discard, persistent; 2310 unsigned int indirect_segments; 2311 2312 info->feature_flush = 0; 2313 2314 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2315 "feature-barrier", "%d", &barrier, 2316 NULL); 2317 2318 /* 2319 * If there's no "feature-barrier" defined, then it means 2320 * we're dealing with a very old backend which writes 2321 * synchronously; nothing to do. 2322 * 2323 * If there are barriers, then we use flush. 2324 */ 2325 if (!err && barrier) 2326 info->feature_flush = REQ_FLUSH | REQ_FUA; 2327 /* 2328 * And if there is "feature-flush-cache" use that above 2329 * barriers. 2330 */ 2331 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2332 "feature-flush-cache", "%d", &flush, 2333 NULL); 2334 2335 if (!err && flush) 2336 info->feature_flush = REQ_FLUSH; 2337 2338 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2339 "feature-discard", "%d", &discard, 2340 NULL); 2341 2342 if (!err && discard) 2343 blkfront_setup_discard(info); 2344 2345 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2346 "feature-persistent", "%u", &persistent, 2347 NULL); 2348 if (err) 2349 info->feature_persistent = 0; 2350 else 2351 info->feature_persistent = persistent; 2352 2353 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2354 "feature-max-indirect-segments", "%u", &indirect_segments, 2355 NULL); 2356 if (err) 2357 info->max_indirect_segments = 0; 2358 else 2359 info->max_indirect_segments = min(indirect_segments, 2360 xen_blkif_max_segments); 2361 } 2362 2363 /* 2364 * Invoked when the backend is finally 'ready' (and has told produced 2365 * the details about the physical device - #sectors, size, etc). 2366 */ 2367 static void blkfront_connect(struct blkfront_info *info) 2368 { 2369 unsigned long long sectors; 2370 unsigned long sector_size; 2371 unsigned int physical_sector_size; 2372 unsigned int binfo; 2373 int err, i; 2374 2375 switch (info->connected) { 2376 case BLKIF_STATE_CONNECTED: 2377 /* 2378 * Potentially, the back-end may be signalling 2379 * a capacity change; update the capacity. 2380 */ 2381 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2382 "sectors", "%Lu", §ors); 2383 if (XENBUS_EXIST_ERR(err)) 2384 return; 2385 printk(KERN_INFO "Setting capacity to %Lu\n", 2386 sectors); 2387 set_capacity(info->gd, sectors); 2388 revalidate_disk(info->gd); 2389 2390 return; 2391 case BLKIF_STATE_SUSPENDED: 2392 /* 2393 * If we are recovering from suspension, we need to wait 2394 * for the backend to announce it's features before 2395 * reconnecting, at least we need to know if the backend 2396 * supports indirect descriptors, and how many. 2397 */ 2398 blkif_recover(info); 2399 return; 2400 2401 default: 2402 break; 2403 } 2404 2405 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 2406 __func__, info->xbdev->otherend); 2407 2408 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 2409 "sectors", "%llu", §ors, 2410 "info", "%u", &binfo, 2411 "sector-size", "%lu", §or_size, 2412 NULL); 2413 if (err) { 2414 xenbus_dev_fatal(info->xbdev, err, 2415 "reading backend fields at %s", 2416 info->xbdev->otherend); 2417 return; 2418 } 2419 2420 /* 2421 * physcial-sector-size is a newer field, so old backends may not 2422 * provide this. Assume physical sector size to be the same as 2423 * sector_size in that case. 2424 */ 2425 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 2426 "physical-sector-size", "%u", &physical_sector_size); 2427 if (err != 1) 2428 physical_sector_size = sector_size; 2429 2430 blkfront_gather_backend_features(info); 2431 for (i = 0; i < info->nr_rings; i++) { 2432 err = blkfront_setup_indirect(&info->rinfo[i]); 2433 if (err) { 2434 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 2435 info->xbdev->otherend); 2436 blkif_free(info, 0); 2437 break; 2438 } 2439 } 2440 2441 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 2442 physical_sector_size); 2443 if (err) { 2444 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 2445 info->xbdev->otherend); 2446 return; 2447 } 2448 2449 xenbus_switch_state(info->xbdev, XenbusStateConnected); 2450 2451 /* Kick pending requests. */ 2452 info->connected = BLKIF_STATE_CONNECTED; 2453 for (i = 0; i < info->nr_rings; i++) 2454 kick_pending_request_queues(&info->rinfo[i]); 2455 2456 add_disk(info->gd); 2457 2458 info->is_ready = 1; 2459 } 2460 2461 /** 2462 * Callback received when the backend's state changes. 2463 */ 2464 static void blkback_changed(struct xenbus_device *dev, 2465 enum xenbus_state backend_state) 2466 { 2467 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2468 2469 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 2470 2471 switch (backend_state) { 2472 case XenbusStateInitWait: 2473 if (dev->state != XenbusStateInitialising) 2474 break; 2475 if (talk_to_blkback(dev, info)) 2476 break; 2477 case XenbusStateInitialising: 2478 case XenbusStateInitialised: 2479 case XenbusStateReconfiguring: 2480 case XenbusStateReconfigured: 2481 case XenbusStateUnknown: 2482 break; 2483 2484 case XenbusStateConnected: 2485 if (dev->state != XenbusStateInitialised) { 2486 if (talk_to_blkback(dev, info)) 2487 break; 2488 } 2489 blkfront_connect(info); 2490 break; 2491 2492 case XenbusStateClosed: 2493 if (dev->state == XenbusStateClosed) 2494 break; 2495 /* Missed the backend's Closing state -- fallthrough */ 2496 case XenbusStateClosing: 2497 if (info) 2498 blkfront_closing(info); 2499 break; 2500 } 2501 } 2502 2503 static int blkfront_remove(struct xenbus_device *xbdev) 2504 { 2505 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 2506 struct block_device *bdev = NULL; 2507 struct gendisk *disk; 2508 2509 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 2510 2511 blkif_free(info, 0); 2512 2513 mutex_lock(&info->mutex); 2514 2515 disk = info->gd; 2516 if (disk) 2517 bdev = bdget_disk(disk, 0); 2518 2519 info->xbdev = NULL; 2520 mutex_unlock(&info->mutex); 2521 2522 if (!bdev) { 2523 kfree(info); 2524 return 0; 2525 } 2526 2527 /* 2528 * The xbdev was removed before we reached the Closed 2529 * state. See if it's safe to remove the disk. If the bdev 2530 * isn't closed yet, we let release take care of it. 2531 */ 2532 2533 mutex_lock(&bdev->bd_mutex); 2534 info = disk->private_data; 2535 2536 dev_warn(disk_to_dev(disk), 2537 "%s was hot-unplugged, %d stale handles\n", 2538 xbdev->nodename, bdev->bd_openers); 2539 2540 if (info && !bdev->bd_openers) { 2541 xlvbd_release_gendisk(info); 2542 disk->private_data = NULL; 2543 kfree(info); 2544 } 2545 2546 mutex_unlock(&bdev->bd_mutex); 2547 bdput(bdev); 2548 2549 return 0; 2550 } 2551 2552 static int blkfront_is_ready(struct xenbus_device *dev) 2553 { 2554 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 2555 2556 return info->is_ready && info->xbdev; 2557 } 2558 2559 static int blkif_open(struct block_device *bdev, fmode_t mode) 2560 { 2561 struct gendisk *disk = bdev->bd_disk; 2562 struct blkfront_info *info; 2563 int err = 0; 2564 2565 mutex_lock(&blkfront_mutex); 2566 2567 info = disk->private_data; 2568 if (!info) { 2569 /* xbdev gone */ 2570 err = -ERESTARTSYS; 2571 goto out; 2572 } 2573 2574 mutex_lock(&info->mutex); 2575 2576 if (!info->gd) 2577 /* xbdev is closed */ 2578 err = -ERESTARTSYS; 2579 2580 mutex_unlock(&info->mutex); 2581 2582 out: 2583 mutex_unlock(&blkfront_mutex); 2584 return err; 2585 } 2586 2587 static void blkif_release(struct gendisk *disk, fmode_t mode) 2588 { 2589 struct blkfront_info *info = disk->private_data; 2590 struct block_device *bdev; 2591 struct xenbus_device *xbdev; 2592 2593 mutex_lock(&blkfront_mutex); 2594 2595 bdev = bdget_disk(disk, 0); 2596 2597 if (!bdev) { 2598 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2599 goto out_mutex; 2600 } 2601 if (bdev->bd_openers) 2602 goto out; 2603 2604 /* 2605 * Check if we have been instructed to close. We will have 2606 * deferred this request, because the bdev was still open. 2607 */ 2608 2609 mutex_lock(&info->mutex); 2610 xbdev = info->xbdev; 2611 2612 if (xbdev && xbdev->state == XenbusStateClosing) { 2613 /* pending switch to state closed */ 2614 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2615 xlvbd_release_gendisk(info); 2616 xenbus_frontend_closed(info->xbdev); 2617 } 2618 2619 mutex_unlock(&info->mutex); 2620 2621 if (!xbdev) { 2622 /* sudden device removal */ 2623 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2624 xlvbd_release_gendisk(info); 2625 disk->private_data = NULL; 2626 kfree(info); 2627 } 2628 2629 out: 2630 bdput(bdev); 2631 out_mutex: 2632 mutex_unlock(&blkfront_mutex); 2633 } 2634 2635 static const struct block_device_operations xlvbd_block_fops = 2636 { 2637 .owner = THIS_MODULE, 2638 .open = blkif_open, 2639 .release = blkif_release, 2640 .getgeo = blkif_getgeo, 2641 .ioctl = blkif_ioctl, 2642 }; 2643 2644 2645 static const struct xenbus_device_id blkfront_ids[] = { 2646 { "vbd" }, 2647 { "" } 2648 }; 2649 2650 static struct xenbus_driver blkfront_driver = { 2651 .ids = blkfront_ids, 2652 .probe = blkfront_probe, 2653 .remove = blkfront_remove, 2654 .resume = blkfront_resume, 2655 .otherend_changed = blkback_changed, 2656 .is_ready = blkfront_is_ready, 2657 }; 2658 2659 static int __init xlblk_init(void) 2660 { 2661 int ret; 2662 int nr_cpus = num_online_cpus(); 2663 2664 if (!xen_domain()) 2665 return -ENODEV; 2666 2667 if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) { 2668 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n", 2669 xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER); 2670 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER; 2671 } 2672 2673 if (xen_blkif_max_queues > nr_cpus) { 2674 pr_info("Invalid max_queues (%d), will use default max: %d.\n", 2675 xen_blkif_max_queues, nr_cpus); 2676 xen_blkif_max_queues = nr_cpus; 2677 } 2678 2679 if (!xen_has_pv_disk_devices()) 2680 return -ENODEV; 2681 2682 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2683 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2684 XENVBD_MAJOR, DEV_NAME); 2685 return -ENODEV; 2686 } 2687 2688 ret = xenbus_register_frontend(&blkfront_driver); 2689 if (ret) { 2690 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2691 return ret; 2692 } 2693 2694 return 0; 2695 } 2696 module_init(xlblk_init); 2697 2698 2699 static void __exit xlblk_exit(void) 2700 { 2701 xenbus_unregister_driver(&blkfront_driver); 2702 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2703 kfree(minors); 2704 } 2705 module_exit(xlblk_exit); 2706 2707 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2708 MODULE_LICENSE("GPL"); 2709 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2710 MODULE_ALIAS("xen:vbd"); 2711 MODULE_ALIAS("xenblk"); 2712