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/hdreg.h> 41 #include <linux/cdrom.h> 42 #include <linux/module.h> 43 #include <linux/slab.h> 44 #include <linux/mutex.h> 45 #include <linux/scatterlist.h> 46 #include <linux/bitmap.h> 47 #include <linux/list.h> 48 49 #include <xen/xen.h> 50 #include <xen/xenbus.h> 51 #include <xen/grant_table.h> 52 #include <xen/events.h> 53 #include <xen/page.h> 54 #include <xen/platform_pci.h> 55 56 #include <xen/interface/grant_table.h> 57 #include <xen/interface/io/blkif.h> 58 #include <xen/interface/io/protocols.h> 59 60 #include <asm/xen/hypervisor.h> 61 62 enum blkif_state { 63 BLKIF_STATE_DISCONNECTED, 64 BLKIF_STATE_CONNECTED, 65 BLKIF_STATE_SUSPENDED, 66 }; 67 68 struct grant { 69 grant_ref_t gref; 70 unsigned long pfn; 71 struct list_head node; 72 }; 73 74 struct blk_shadow { 75 struct blkif_request req; 76 struct request *request; 77 struct grant **grants_used; 78 struct grant **indirect_grants; 79 struct scatterlist *sg; 80 }; 81 82 struct split_bio { 83 struct bio *bio; 84 atomic_t pending; 85 int err; 86 }; 87 88 static DEFINE_MUTEX(blkfront_mutex); 89 static const struct block_device_operations xlvbd_block_fops; 90 91 /* 92 * Maximum number of segments in indirect requests, the actual value used by 93 * the frontend driver is the minimum of this value and the value provided 94 * by the backend driver. 95 */ 96 97 static unsigned int xen_blkif_max_segments = 32; 98 module_param_named(max, xen_blkif_max_segments, int, S_IRUGO); 99 MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)"); 100 101 #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) 102 103 /* 104 * We have one of these per vbd, whether ide, scsi or 'other'. They 105 * hang in private_data off the gendisk structure. We may end up 106 * putting all kinds of interesting stuff here :-) 107 */ 108 struct blkfront_info 109 { 110 spinlock_t io_lock; 111 struct mutex mutex; 112 struct xenbus_device *xbdev; 113 struct gendisk *gd; 114 int vdevice; 115 blkif_vdev_t handle; 116 enum blkif_state connected; 117 int ring_ref; 118 struct blkif_front_ring ring; 119 unsigned int evtchn, irq; 120 struct request_queue *rq; 121 struct work_struct work; 122 struct gnttab_free_callback callback; 123 struct blk_shadow shadow[BLK_RING_SIZE]; 124 struct list_head grants; 125 struct list_head indirect_pages; 126 unsigned int persistent_gnts_c; 127 unsigned long shadow_free; 128 unsigned int feature_flush; 129 unsigned int flush_op; 130 unsigned int feature_discard:1; 131 unsigned int feature_secdiscard:1; 132 unsigned int discard_granularity; 133 unsigned int discard_alignment; 134 unsigned int feature_persistent:1; 135 unsigned int max_indirect_segments; 136 int is_ready; 137 }; 138 139 static unsigned int nr_minors; 140 static unsigned long *minors; 141 static DEFINE_SPINLOCK(minor_lock); 142 143 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \ 144 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE) 145 #define GRANT_INVALID_REF 0 146 147 #define PARTS_PER_DISK 16 148 #define PARTS_PER_EXT_DISK 256 149 150 #define BLKIF_MAJOR(dev) ((dev)>>8) 151 #define BLKIF_MINOR(dev) ((dev) & 0xff) 152 153 #define EXT_SHIFT 28 154 #define EXTENDED (1<<EXT_SHIFT) 155 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 156 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 157 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 158 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 159 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 160 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 161 162 #define DEV_NAME "xvd" /* name in /dev */ 163 164 #define SEGS_PER_INDIRECT_FRAME \ 165 (PAGE_SIZE/sizeof(struct blkif_request_segment)) 166 #define INDIRECT_GREFS(_segs) \ 167 ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME) 168 169 static int blkfront_setup_indirect(struct blkfront_info *info); 170 171 static int get_id_from_freelist(struct blkfront_info *info) 172 { 173 unsigned long free = info->shadow_free; 174 BUG_ON(free >= BLK_RING_SIZE); 175 info->shadow_free = info->shadow[free].req.u.rw.id; 176 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 177 return free; 178 } 179 180 static int add_id_to_freelist(struct blkfront_info *info, 181 unsigned long id) 182 { 183 if (info->shadow[id].req.u.rw.id != id) 184 return -EINVAL; 185 if (info->shadow[id].request == NULL) 186 return -EINVAL; 187 info->shadow[id].req.u.rw.id = info->shadow_free; 188 info->shadow[id].request = NULL; 189 info->shadow_free = id; 190 return 0; 191 } 192 193 static int fill_grant_buffer(struct blkfront_info *info, int num) 194 { 195 struct page *granted_page; 196 struct grant *gnt_list_entry, *n; 197 int i = 0; 198 199 while(i < num) { 200 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO); 201 if (!gnt_list_entry) 202 goto out_of_memory; 203 204 if (info->feature_persistent) { 205 granted_page = alloc_page(GFP_NOIO); 206 if (!granted_page) { 207 kfree(gnt_list_entry); 208 goto out_of_memory; 209 } 210 gnt_list_entry->pfn = page_to_pfn(granted_page); 211 } 212 213 gnt_list_entry->gref = GRANT_INVALID_REF; 214 list_add(&gnt_list_entry->node, &info->grants); 215 i++; 216 } 217 218 return 0; 219 220 out_of_memory: 221 list_for_each_entry_safe(gnt_list_entry, n, 222 &info->grants, node) { 223 list_del(&gnt_list_entry->node); 224 if (info->feature_persistent) 225 __free_page(pfn_to_page(gnt_list_entry->pfn)); 226 kfree(gnt_list_entry); 227 i--; 228 } 229 BUG_ON(i != 0); 230 return -ENOMEM; 231 } 232 233 static struct grant *get_grant(grant_ref_t *gref_head, 234 unsigned long pfn, 235 struct blkfront_info *info) 236 { 237 struct grant *gnt_list_entry; 238 unsigned long buffer_mfn; 239 240 BUG_ON(list_empty(&info->grants)); 241 gnt_list_entry = list_first_entry(&info->grants, struct grant, 242 node); 243 list_del(&gnt_list_entry->node); 244 245 if (gnt_list_entry->gref != GRANT_INVALID_REF) { 246 info->persistent_gnts_c--; 247 return gnt_list_entry; 248 } 249 250 /* Assign a gref to this page */ 251 gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head); 252 BUG_ON(gnt_list_entry->gref == -ENOSPC); 253 if (!info->feature_persistent) { 254 BUG_ON(!pfn); 255 gnt_list_entry->pfn = pfn; 256 } 257 buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn); 258 gnttab_grant_foreign_access_ref(gnt_list_entry->gref, 259 info->xbdev->otherend_id, 260 buffer_mfn, 0); 261 return gnt_list_entry; 262 } 263 264 static const char *op_name(int op) 265 { 266 static const char *const names[] = { 267 [BLKIF_OP_READ] = "read", 268 [BLKIF_OP_WRITE] = "write", 269 [BLKIF_OP_WRITE_BARRIER] = "barrier", 270 [BLKIF_OP_FLUSH_DISKCACHE] = "flush", 271 [BLKIF_OP_DISCARD] = "discard" }; 272 273 if (op < 0 || op >= ARRAY_SIZE(names)) 274 return "unknown"; 275 276 if (!names[op]) 277 return "reserved"; 278 279 return names[op]; 280 } 281 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 282 { 283 unsigned int end = minor + nr; 284 int rc; 285 286 if (end > nr_minors) { 287 unsigned long *bitmap, *old; 288 289 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 290 GFP_KERNEL); 291 if (bitmap == NULL) 292 return -ENOMEM; 293 294 spin_lock(&minor_lock); 295 if (end > nr_minors) { 296 old = minors; 297 memcpy(bitmap, minors, 298 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 299 minors = bitmap; 300 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 301 } else 302 old = bitmap; 303 spin_unlock(&minor_lock); 304 kfree(old); 305 } 306 307 spin_lock(&minor_lock); 308 if (find_next_bit(minors, end, minor) >= end) { 309 bitmap_set(minors, minor, nr); 310 rc = 0; 311 } else 312 rc = -EBUSY; 313 spin_unlock(&minor_lock); 314 315 return rc; 316 } 317 318 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 319 { 320 unsigned int end = minor + nr; 321 322 BUG_ON(end > nr_minors); 323 spin_lock(&minor_lock); 324 bitmap_clear(minors, minor, nr); 325 spin_unlock(&minor_lock); 326 } 327 328 static void blkif_restart_queue_callback(void *arg) 329 { 330 struct blkfront_info *info = (struct blkfront_info *)arg; 331 schedule_work(&info->work); 332 } 333 334 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 335 { 336 /* We don't have real geometry info, but let's at least return 337 values consistent with the size of the device */ 338 sector_t nsect = get_capacity(bd->bd_disk); 339 sector_t cylinders = nsect; 340 341 hg->heads = 0xff; 342 hg->sectors = 0x3f; 343 sector_div(cylinders, hg->heads * hg->sectors); 344 hg->cylinders = cylinders; 345 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 346 hg->cylinders = 0xffff; 347 return 0; 348 } 349 350 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 351 unsigned command, unsigned long argument) 352 { 353 struct blkfront_info *info = bdev->bd_disk->private_data; 354 int i; 355 356 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 357 command, (long)argument); 358 359 switch (command) { 360 case CDROMMULTISESSION: 361 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 362 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 363 if (put_user(0, (char __user *)(argument + i))) 364 return -EFAULT; 365 return 0; 366 367 case CDROM_GET_CAPABILITY: { 368 struct gendisk *gd = info->gd; 369 if (gd->flags & GENHD_FL_CD) 370 return 0; 371 return -EINVAL; 372 } 373 374 default: 375 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 376 command);*/ 377 return -EINVAL; /* same return as native Linux */ 378 } 379 380 return 0; 381 } 382 383 /* 384 * Generate a Xen blkfront IO request from a blk layer request. Reads 385 * and writes are handled as expected. 386 * 387 * @req: a request struct 388 */ 389 static int blkif_queue_request(struct request *req) 390 { 391 struct blkfront_info *info = req->rq_disk->private_data; 392 struct blkif_request *ring_req; 393 unsigned long id; 394 unsigned int fsect, lsect; 395 int i, ref, n; 396 struct blkif_request_segment *segments = NULL; 397 398 /* 399 * Used to store if we are able to queue the request by just using 400 * existing persistent grants, or if we have to get new grants, 401 * as there are not sufficiently many free. 402 */ 403 bool new_persistent_gnts; 404 grant_ref_t gref_head; 405 struct grant *gnt_list_entry = NULL; 406 struct scatterlist *sg; 407 int nseg, max_grefs; 408 409 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 410 return 1; 411 412 max_grefs = req->nr_phys_segments; 413 if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST) 414 /* 415 * If we are using indirect segments we need to account 416 * for the indirect grefs used in the request. 417 */ 418 max_grefs += INDIRECT_GREFS(req->nr_phys_segments); 419 420 /* Check if we have enough grants to allocate a requests */ 421 if (info->persistent_gnts_c < max_grefs) { 422 new_persistent_gnts = 1; 423 if (gnttab_alloc_grant_references( 424 max_grefs - info->persistent_gnts_c, 425 &gref_head) < 0) { 426 gnttab_request_free_callback( 427 &info->callback, 428 blkif_restart_queue_callback, 429 info, 430 max_grefs); 431 return 1; 432 } 433 } else 434 new_persistent_gnts = 0; 435 436 /* Fill out a communications ring structure. */ 437 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); 438 id = get_id_from_freelist(info); 439 info->shadow[id].request = req; 440 441 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) { 442 ring_req->operation = BLKIF_OP_DISCARD; 443 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 444 ring_req->u.discard.id = id; 445 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req); 446 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) 447 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 448 else 449 ring_req->u.discard.flag = 0; 450 } else { 451 BUG_ON(info->max_indirect_segments == 0 && 452 req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST); 453 BUG_ON(info->max_indirect_segments && 454 req->nr_phys_segments > info->max_indirect_segments); 455 nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg); 456 ring_req->u.rw.id = id; 457 if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) { 458 /* 459 * The indirect operation can only be a BLKIF_OP_READ or 460 * BLKIF_OP_WRITE 461 */ 462 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA)); 463 ring_req->operation = BLKIF_OP_INDIRECT; 464 ring_req->u.indirect.indirect_op = rq_data_dir(req) ? 465 BLKIF_OP_WRITE : BLKIF_OP_READ; 466 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req); 467 ring_req->u.indirect.handle = info->handle; 468 ring_req->u.indirect.nr_segments = nseg; 469 } else { 470 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 471 ring_req->u.rw.handle = info->handle; 472 ring_req->operation = rq_data_dir(req) ? 473 BLKIF_OP_WRITE : BLKIF_OP_READ; 474 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { 475 /* 476 * Ideally we can do an unordered flush-to-disk. In case the 477 * backend onlysupports barriers, use that. A barrier request 478 * a superset of FUA, so we can implement it the same 479 * way. (It's also a FLUSH+FUA, since it is 480 * guaranteed ordered WRT previous writes.) 481 */ 482 ring_req->operation = info->flush_op; 483 } 484 ring_req->u.rw.nr_segments = nseg; 485 } 486 for_each_sg(info->shadow[id].sg, sg, nseg, i) { 487 fsect = sg->offset >> 9; 488 lsect = fsect + (sg->length >> 9) - 1; 489 490 if ((ring_req->operation == BLKIF_OP_INDIRECT) && 491 (i % SEGS_PER_INDIRECT_FRAME == 0)) { 492 unsigned long uninitialized_var(pfn); 493 494 if (segments) 495 kunmap_atomic(segments); 496 497 n = i / SEGS_PER_INDIRECT_FRAME; 498 if (!info->feature_persistent) { 499 struct page *indirect_page; 500 501 /* Fetch a pre-allocated page to use for indirect grefs */ 502 BUG_ON(list_empty(&info->indirect_pages)); 503 indirect_page = list_first_entry(&info->indirect_pages, 504 struct page, lru); 505 list_del(&indirect_page->lru); 506 pfn = page_to_pfn(indirect_page); 507 } 508 gnt_list_entry = get_grant(&gref_head, pfn, info); 509 info->shadow[id].indirect_grants[n] = gnt_list_entry; 510 segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); 511 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref; 512 } 513 514 gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info); 515 ref = gnt_list_entry->gref; 516 517 info->shadow[id].grants_used[i] = gnt_list_entry; 518 519 if (rq_data_dir(req) && info->feature_persistent) { 520 char *bvec_data; 521 void *shared_data; 522 523 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 524 525 shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn)); 526 bvec_data = kmap_atomic(sg_page(sg)); 527 528 /* 529 * this does not wipe data stored outside the 530 * range sg->offset..sg->offset+sg->length. 531 * Therefore, blkback *could* see data from 532 * previous requests. This is OK as long as 533 * persistent grants are shared with just one 534 * domain. It may need refactoring if this 535 * changes 536 */ 537 memcpy(shared_data + sg->offset, 538 bvec_data + sg->offset, 539 sg->length); 540 541 kunmap_atomic(bvec_data); 542 kunmap_atomic(shared_data); 543 } 544 if (ring_req->operation != BLKIF_OP_INDIRECT) { 545 ring_req->u.rw.seg[i] = 546 (struct blkif_request_segment) { 547 .gref = ref, 548 .first_sect = fsect, 549 .last_sect = lsect }; 550 } else { 551 n = i % SEGS_PER_INDIRECT_FRAME; 552 segments[n] = 553 (struct blkif_request_segment) { 554 .gref = ref, 555 .first_sect = fsect, 556 .last_sect = lsect }; 557 } 558 } 559 if (segments) 560 kunmap_atomic(segments); 561 } 562 563 info->ring.req_prod_pvt++; 564 565 /* Keep a private copy so we can reissue requests when recovering. */ 566 info->shadow[id].req = *ring_req; 567 568 if (new_persistent_gnts) 569 gnttab_free_grant_references(gref_head); 570 571 return 0; 572 } 573 574 575 static inline void flush_requests(struct blkfront_info *info) 576 { 577 int notify; 578 579 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); 580 581 if (notify) 582 notify_remote_via_irq(info->irq); 583 } 584 585 /* 586 * do_blkif_request 587 * read a block; request is in a request queue 588 */ 589 static void do_blkif_request(struct request_queue *rq) 590 { 591 struct blkfront_info *info = NULL; 592 struct request *req; 593 int queued; 594 595 pr_debug("Entered do_blkif_request\n"); 596 597 queued = 0; 598 599 while ((req = blk_peek_request(rq)) != NULL) { 600 info = req->rq_disk->private_data; 601 602 if (RING_FULL(&info->ring)) 603 goto wait; 604 605 blk_start_request(req); 606 607 if ((req->cmd_type != REQ_TYPE_FS) || 608 ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) && 609 !info->flush_op)) { 610 __blk_end_request_all(req, -EIO); 611 continue; 612 } 613 614 pr_debug("do_blk_req %p: cmd %p, sec %lx, " 615 "(%u/%u) buffer:%p [%s]\n", 616 req, req->cmd, (unsigned long)blk_rq_pos(req), 617 blk_rq_cur_sectors(req), blk_rq_sectors(req), 618 req->buffer, rq_data_dir(req) ? "write" : "read"); 619 620 if (blkif_queue_request(req)) { 621 blk_requeue_request(rq, req); 622 wait: 623 /* Avoid pointless unplugs. */ 624 blk_stop_queue(rq); 625 break; 626 } 627 628 queued++; 629 } 630 631 if (queued != 0) 632 flush_requests(info); 633 } 634 635 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size, 636 unsigned int physical_sector_size, 637 unsigned int segments) 638 { 639 struct request_queue *rq; 640 struct blkfront_info *info = gd->private_data; 641 642 rq = blk_init_queue(do_blkif_request, &info->io_lock); 643 if (rq == NULL) 644 return -1; 645 646 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 647 648 if (info->feature_discard) { 649 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); 650 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 651 rq->limits.discard_granularity = info->discard_granularity; 652 rq->limits.discard_alignment = info->discard_alignment; 653 if (info->feature_secdiscard) 654 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq); 655 } 656 657 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 658 blk_queue_logical_block_size(rq, sector_size); 659 blk_queue_physical_block_size(rq, physical_sector_size); 660 blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512); 661 662 /* Each segment in a request is up to an aligned page in size. */ 663 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 664 blk_queue_max_segment_size(rq, PAGE_SIZE); 665 666 /* Ensure a merged request will fit in a single I/O ring slot. */ 667 blk_queue_max_segments(rq, segments); 668 669 /* Make sure buffer addresses are sector-aligned. */ 670 blk_queue_dma_alignment(rq, 511); 671 672 /* Make sure we don't use bounce buffers. */ 673 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); 674 675 gd->queue = rq; 676 677 return 0; 678 } 679 680 681 static void xlvbd_flush(struct blkfront_info *info) 682 { 683 blk_queue_flush(info->rq, info->feature_flush); 684 printk(KERN_INFO "blkfront: %s: %s: %s %s %s %s %s\n", 685 info->gd->disk_name, 686 info->flush_op == BLKIF_OP_WRITE_BARRIER ? 687 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ? 688 "flush diskcache" : "barrier or flush"), 689 info->feature_flush ? "enabled;" : "disabled;", 690 "persistent grants:", 691 info->feature_persistent ? "enabled;" : "disabled;", 692 "indirect descriptors:", 693 info->max_indirect_segments ? "enabled;" : "disabled;"); 694 } 695 696 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 697 { 698 int major; 699 major = BLKIF_MAJOR(vdevice); 700 *minor = BLKIF_MINOR(vdevice); 701 switch (major) { 702 case XEN_IDE0_MAJOR: 703 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 704 *minor = ((*minor / 64) * PARTS_PER_DISK) + 705 EMULATED_HD_DISK_MINOR_OFFSET; 706 break; 707 case XEN_IDE1_MAJOR: 708 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 709 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 710 EMULATED_HD_DISK_MINOR_OFFSET; 711 break; 712 case XEN_SCSI_DISK0_MAJOR: 713 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 714 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 715 break; 716 case XEN_SCSI_DISK1_MAJOR: 717 case XEN_SCSI_DISK2_MAJOR: 718 case XEN_SCSI_DISK3_MAJOR: 719 case XEN_SCSI_DISK4_MAJOR: 720 case XEN_SCSI_DISK5_MAJOR: 721 case XEN_SCSI_DISK6_MAJOR: 722 case XEN_SCSI_DISK7_MAJOR: 723 *offset = (*minor / PARTS_PER_DISK) + 724 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 725 EMULATED_SD_DISK_NAME_OFFSET; 726 *minor = *minor + 727 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 728 EMULATED_SD_DISK_MINOR_OFFSET; 729 break; 730 case XEN_SCSI_DISK8_MAJOR: 731 case XEN_SCSI_DISK9_MAJOR: 732 case XEN_SCSI_DISK10_MAJOR: 733 case XEN_SCSI_DISK11_MAJOR: 734 case XEN_SCSI_DISK12_MAJOR: 735 case XEN_SCSI_DISK13_MAJOR: 736 case XEN_SCSI_DISK14_MAJOR: 737 case XEN_SCSI_DISK15_MAJOR: 738 *offset = (*minor / PARTS_PER_DISK) + 739 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 740 EMULATED_SD_DISK_NAME_OFFSET; 741 *minor = *minor + 742 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 743 EMULATED_SD_DISK_MINOR_OFFSET; 744 break; 745 case XENVBD_MAJOR: 746 *offset = *minor / PARTS_PER_DISK; 747 break; 748 default: 749 printk(KERN_WARNING "blkfront: your disk configuration is " 750 "incorrect, please use an xvd device instead\n"); 751 return -ENODEV; 752 } 753 return 0; 754 } 755 756 static char *encode_disk_name(char *ptr, unsigned int n) 757 { 758 if (n >= 26) 759 ptr = encode_disk_name(ptr, n / 26 - 1); 760 *ptr = 'a' + n % 26; 761 return ptr + 1; 762 } 763 764 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 765 struct blkfront_info *info, 766 u16 vdisk_info, u16 sector_size, 767 unsigned int physical_sector_size) 768 { 769 struct gendisk *gd; 770 int nr_minors = 1; 771 int err; 772 unsigned int offset; 773 int minor; 774 int nr_parts; 775 char *ptr; 776 777 BUG_ON(info->gd != NULL); 778 BUG_ON(info->rq != NULL); 779 780 if ((info->vdevice>>EXT_SHIFT) > 1) { 781 /* this is above the extended range; something is wrong */ 782 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 783 return -ENODEV; 784 } 785 786 if (!VDEV_IS_EXTENDED(info->vdevice)) { 787 err = xen_translate_vdev(info->vdevice, &minor, &offset); 788 if (err) 789 return err; 790 nr_parts = PARTS_PER_DISK; 791 } else { 792 minor = BLKIF_MINOR_EXT(info->vdevice); 793 nr_parts = PARTS_PER_EXT_DISK; 794 offset = minor / nr_parts; 795 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 796 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 797 "emulated IDE disks,\n\t choose an xvd device name" 798 "from xvde on\n", info->vdevice); 799 } 800 if (minor >> MINORBITS) { 801 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n", 802 info->vdevice, minor); 803 return -ENODEV; 804 } 805 806 if ((minor % nr_parts) == 0) 807 nr_minors = nr_parts; 808 809 err = xlbd_reserve_minors(minor, nr_minors); 810 if (err) 811 goto out; 812 err = -ENODEV; 813 814 gd = alloc_disk(nr_minors); 815 if (gd == NULL) 816 goto release; 817 818 strcpy(gd->disk_name, DEV_NAME); 819 ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset); 820 BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN); 821 if (nr_minors > 1) 822 *ptr = 0; 823 else 824 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr, 825 "%d", minor & (nr_parts - 1)); 826 827 gd->major = XENVBD_MAJOR; 828 gd->first_minor = minor; 829 gd->fops = &xlvbd_block_fops; 830 gd->private_data = info; 831 gd->driverfs_dev = &(info->xbdev->dev); 832 set_capacity(gd, capacity); 833 834 if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size, 835 info->max_indirect_segments ? : 836 BLKIF_MAX_SEGMENTS_PER_REQUEST)) { 837 del_gendisk(gd); 838 goto release; 839 } 840 841 info->rq = gd->queue; 842 info->gd = gd; 843 844 xlvbd_flush(info); 845 846 if (vdisk_info & VDISK_READONLY) 847 set_disk_ro(gd, 1); 848 849 if (vdisk_info & VDISK_REMOVABLE) 850 gd->flags |= GENHD_FL_REMOVABLE; 851 852 if (vdisk_info & VDISK_CDROM) 853 gd->flags |= GENHD_FL_CD; 854 855 return 0; 856 857 release: 858 xlbd_release_minors(minor, nr_minors); 859 out: 860 return err; 861 } 862 863 static void xlvbd_release_gendisk(struct blkfront_info *info) 864 { 865 unsigned int minor, nr_minors; 866 unsigned long flags; 867 868 if (info->rq == NULL) 869 return; 870 871 spin_lock_irqsave(&info->io_lock, flags); 872 873 /* No more blkif_request(). */ 874 blk_stop_queue(info->rq); 875 876 /* No more gnttab callback work. */ 877 gnttab_cancel_free_callback(&info->callback); 878 spin_unlock_irqrestore(&info->io_lock, flags); 879 880 /* Flush gnttab callback work. Must be done with no locks held. */ 881 flush_work(&info->work); 882 883 del_gendisk(info->gd); 884 885 minor = info->gd->first_minor; 886 nr_minors = info->gd->minors; 887 xlbd_release_minors(minor, nr_minors); 888 889 blk_cleanup_queue(info->rq); 890 info->rq = NULL; 891 892 put_disk(info->gd); 893 info->gd = NULL; 894 } 895 896 static void kick_pending_request_queues(struct blkfront_info *info) 897 { 898 if (!RING_FULL(&info->ring)) { 899 /* Re-enable calldowns. */ 900 blk_start_queue(info->rq); 901 /* Kick things off immediately. */ 902 do_blkif_request(info->rq); 903 } 904 } 905 906 static void blkif_restart_queue(struct work_struct *work) 907 { 908 struct blkfront_info *info = container_of(work, struct blkfront_info, work); 909 910 spin_lock_irq(&info->io_lock); 911 if (info->connected == BLKIF_STATE_CONNECTED) 912 kick_pending_request_queues(info); 913 spin_unlock_irq(&info->io_lock); 914 } 915 916 static void blkif_free(struct blkfront_info *info, int suspend) 917 { 918 struct grant *persistent_gnt; 919 struct grant *n; 920 int i, j, segs; 921 922 /* Prevent new requests being issued until we fix things up. */ 923 spin_lock_irq(&info->io_lock); 924 info->connected = suspend ? 925 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 926 /* No more blkif_request(). */ 927 if (info->rq) 928 blk_stop_queue(info->rq); 929 930 /* Remove all persistent grants */ 931 if (!list_empty(&info->grants)) { 932 list_for_each_entry_safe(persistent_gnt, n, 933 &info->grants, node) { 934 list_del(&persistent_gnt->node); 935 if (persistent_gnt->gref != GRANT_INVALID_REF) { 936 gnttab_end_foreign_access(persistent_gnt->gref, 937 0, 0UL); 938 info->persistent_gnts_c--; 939 } 940 if (info->feature_persistent) 941 __free_page(pfn_to_page(persistent_gnt->pfn)); 942 kfree(persistent_gnt); 943 } 944 } 945 BUG_ON(info->persistent_gnts_c != 0); 946 947 /* 948 * Remove indirect pages, this only happens when using indirect 949 * descriptors but not persistent grants 950 */ 951 if (!list_empty(&info->indirect_pages)) { 952 struct page *indirect_page, *n; 953 954 BUG_ON(info->feature_persistent); 955 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 956 list_del(&indirect_page->lru); 957 __free_page(indirect_page); 958 } 959 } 960 961 for (i = 0; i < BLK_RING_SIZE; i++) { 962 /* 963 * Clear persistent grants present in requests already 964 * on the shared ring 965 */ 966 if (!info->shadow[i].request) 967 goto free_shadow; 968 969 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ? 970 info->shadow[i].req.u.indirect.nr_segments : 971 info->shadow[i].req.u.rw.nr_segments; 972 for (j = 0; j < segs; j++) { 973 persistent_gnt = info->shadow[i].grants_used[j]; 974 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 975 if (info->feature_persistent) 976 __free_page(pfn_to_page(persistent_gnt->pfn)); 977 kfree(persistent_gnt); 978 } 979 980 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT) 981 /* 982 * If this is not an indirect operation don't try to 983 * free indirect segments 984 */ 985 goto free_shadow; 986 987 for (j = 0; j < INDIRECT_GREFS(segs); j++) { 988 persistent_gnt = info->shadow[i].indirect_grants[j]; 989 gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL); 990 __free_page(pfn_to_page(persistent_gnt->pfn)); 991 kfree(persistent_gnt); 992 } 993 994 free_shadow: 995 kfree(info->shadow[i].grants_used); 996 info->shadow[i].grants_used = NULL; 997 kfree(info->shadow[i].indirect_grants); 998 info->shadow[i].indirect_grants = NULL; 999 kfree(info->shadow[i].sg); 1000 info->shadow[i].sg = NULL; 1001 } 1002 1003 /* No more gnttab callback work. */ 1004 gnttab_cancel_free_callback(&info->callback); 1005 spin_unlock_irq(&info->io_lock); 1006 1007 /* Flush gnttab callback work. Must be done with no locks held. */ 1008 flush_work(&info->work); 1009 1010 /* Free resources associated with old device channel. */ 1011 if (info->ring_ref != GRANT_INVALID_REF) { 1012 gnttab_end_foreign_access(info->ring_ref, 0, 1013 (unsigned long)info->ring.sring); 1014 info->ring_ref = GRANT_INVALID_REF; 1015 info->ring.sring = NULL; 1016 } 1017 if (info->irq) 1018 unbind_from_irqhandler(info->irq, info); 1019 info->evtchn = info->irq = 0; 1020 1021 } 1022 1023 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info, 1024 struct blkif_response *bret) 1025 { 1026 int i = 0; 1027 struct scatterlist *sg; 1028 char *bvec_data; 1029 void *shared_data; 1030 int nseg; 1031 1032 nseg = s->req.operation == BLKIF_OP_INDIRECT ? 1033 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments; 1034 1035 if (bret->operation == BLKIF_OP_READ && info->feature_persistent) { 1036 /* 1037 * Copy the data received from the backend into the bvec. 1038 * Since bv_offset can be different than 0, and bv_len different 1039 * than PAGE_SIZE, we have to keep track of the current offset, 1040 * to be sure we are copying the data from the right shared page. 1041 */ 1042 for_each_sg(s->sg, sg, nseg, i) { 1043 BUG_ON(sg->offset + sg->length > PAGE_SIZE); 1044 shared_data = kmap_atomic( 1045 pfn_to_page(s->grants_used[i]->pfn)); 1046 bvec_data = kmap_atomic(sg_page(sg)); 1047 memcpy(bvec_data + sg->offset, 1048 shared_data + sg->offset, 1049 sg->length); 1050 kunmap_atomic(bvec_data); 1051 kunmap_atomic(shared_data); 1052 } 1053 } 1054 /* Add the persistent grant into the list of free grants */ 1055 for (i = 0; i < nseg; i++) { 1056 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) { 1057 /* 1058 * If the grant is still mapped by the backend (the 1059 * backend has chosen to make this grant persistent) 1060 * we add it at the head of the list, so it will be 1061 * reused first. 1062 */ 1063 if (!info->feature_persistent) 1064 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1065 s->grants_used[i]->gref); 1066 list_add(&s->grants_used[i]->node, &info->grants); 1067 info->persistent_gnts_c++; 1068 } else { 1069 /* 1070 * If the grant is not mapped by the backend we end the 1071 * foreign access and add it to the tail of the list, 1072 * so it will not be picked again unless we run out of 1073 * persistent grants. 1074 */ 1075 gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL); 1076 s->grants_used[i]->gref = GRANT_INVALID_REF; 1077 list_add_tail(&s->grants_used[i]->node, &info->grants); 1078 } 1079 } 1080 if (s->req.operation == BLKIF_OP_INDIRECT) { 1081 for (i = 0; i < INDIRECT_GREFS(nseg); i++) { 1082 if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) { 1083 if (!info->feature_persistent) 1084 pr_alert_ratelimited("backed has not unmapped grant: %u\n", 1085 s->indirect_grants[i]->gref); 1086 list_add(&s->indirect_grants[i]->node, &info->grants); 1087 info->persistent_gnts_c++; 1088 } else { 1089 struct page *indirect_page; 1090 1091 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL); 1092 /* 1093 * Add the used indirect page back to the list of 1094 * available pages for indirect grefs. 1095 */ 1096 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn); 1097 list_add(&indirect_page->lru, &info->indirect_pages); 1098 s->indirect_grants[i]->gref = GRANT_INVALID_REF; 1099 list_add_tail(&s->indirect_grants[i]->node, &info->grants); 1100 } 1101 } 1102 } 1103 } 1104 1105 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 1106 { 1107 struct request *req; 1108 struct blkif_response *bret; 1109 RING_IDX i, rp; 1110 unsigned long flags; 1111 struct blkfront_info *info = (struct blkfront_info *)dev_id; 1112 int error; 1113 1114 spin_lock_irqsave(&info->io_lock, flags); 1115 1116 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { 1117 spin_unlock_irqrestore(&info->io_lock, flags); 1118 return IRQ_HANDLED; 1119 } 1120 1121 again: 1122 rp = info->ring.sring->rsp_prod; 1123 rmb(); /* Ensure we see queued responses up to 'rp'. */ 1124 1125 for (i = info->ring.rsp_cons; i != rp; i++) { 1126 unsigned long id; 1127 1128 bret = RING_GET_RESPONSE(&info->ring, i); 1129 id = bret->id; 1130 /* 1131 * The backend has messed up and given us an id that we would 1132 * never have given to it (we stamp it up to BLK_RING_SIZE - 1133 * look in get_id_from_freelist. 1134 */ 1135 if (id >= BLK_RING_SIZE) { 1136 WARN(1, "%s: response to %s has incorrect id (%ld)\n", 1137 info->gd->disk_name, op_name(bret->operation), id); 1138 /* We can't safely get the 'struct request' as 1139 * the id is busted. */ 1140 continue; 1141 } 1142 req = info->shadow[id].request; 1143 1144 if (bret->operation != BLKIF_OP_DISCARD) 1145 blkif_completion(&info->shadow[id], info, bret); 1146 1147 if (add_id_to_freelist(info, id)) { 1148 WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n", 1149 info->gd->disk_name, op_name(bret->operation), id); 1150 continue; 1151 } 1152 1153 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; 1154 switch (bret->operation) { 1155 case BLKIF_OP_DISCARD: 1156 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1157 struct request_queue *rq = info->rq; 1158 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1159 info->gd->disk_name, op_name(bret->operation)); 1160 error = -EOPNOTSUPP; 1161 info->feature_discard = 0; 1162 info->feature_secdiscard = 0; 1163 queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 1164 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq); 1165 } 1166 __blk_end_request_all(req, error); 1167 break; 1168 case BLKIF_OP_FLUSH_DISKCACHE: 1169 case BLKIF_OP_WRITE_BARRIER: 1170 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 1171 printk(KERN_WARNING "blkfront: %s: %s op failed\n", 1172 info->gd->disk_name, op_name(bret->operation)); 1173 error = -EOPNOTSUPP; 1174 } 1175 if (unlikely(bret->status == BLKIF_RSP_ERROR && 1176 info->shadow[id].req.u.rw.nr_segments == 0)) { 1177 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n", 1178 info->gd->disk_name, op_name(bret->operation)); 1179 error = -EOPNOTSUPP; 1180 } 1181 if (unlikely(error)) { 1182 if (error == -EOPNOTSUPP) 1183 error = 0; 1184 info->feature_flush = 0; 1185 info->flush_op = 0; 1186 xlvbd_flush(info); 1187 } 1188 /* fall through */ 1189 case BLKIF_OP_READ: 1190 case BLKIF_OP_WRITE: 1191 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 1192 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 1193 "request: %x\n", bret->status); 1194 1195 __blk_end_request_all(req, error); 1196 break; 1197 default: 1198 BUG(); 1199 } 1200 } 1201 1202 info->ring.rsp_cons = i; 1203 1204 if (i != info->ring.req_prod_pvt) { 1205 int more_to_do; 1206 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 1207 if (more_to_do) 1208 goto again; 1209 } else 1210 info->ring.sring->rsp_event = i + 1; 1211 1212 kick_pending_request_queues(info); 1213 1214 spin_unlock_irqrestore(&info->io_lock, flags); 1215 1216 return IRQ_HANDLED; 1217 } 1218 1219 1220 static int setup_blkring(struct xenbus_device *dev, 1221 struct blkfront_info *info) 1222 { 1223 struct blkif_sring *sring; 1224 int err; 1225 1226 info->ring_ref = GRANT_INVALID_REF; 1227 1228 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH); 1229 if (!sring) { 1230 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 1231 return -ENOMEM; 1232 } 1233 SHARED_RING_INIT(sring); 1234 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 1235 1236 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); 1237 if (err < 0) { 1238 free_page((unsigned long)sring); 1239 info->ring.sring = NULL; 1240 goto fail; 1241 } 1242 info->ring_ref = err; 1243 1244 err = xenbus_alloc_evtchn(dev, &info->evtchn); 1245 if (err) 1246 goto fail; 1247 1248 err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0, 1249 "blkif", info); 1250 if (err <= 0) { 1251 xenbus_dev_fatal(dev, err, 1252 "bind_evtchn_to_irqhandler failed"); 1253 goto fail; 1254 } 1255 info->irq = err; 1256 1257 return 0; 1258 fail: 1259 blkif_free(info, 0); 1260 return err; 1261 } 1262 1263 1264 /* Common code used when first setting up, and when resuming. */ 1265 static int talk_to_blkback(struct xenbus_device *dev, 1266 struct blkfront_info *info) 1267 { 1268 const char *message = NULL; 1269 struct xenbus_transaction xbt; 1270 int err; 1271 1272 /* Create shared ring, alloc event channel. */ 1273 err = setup_blkring(dev, info); 1274 if (err) 1275 goto out; 1276 1277 again: 1278 err = xenbus_transaction_start(&xbt); 1279 if (err) { 1280 xenbus_dev_fatal(dev, err, "starting transaction"); 1281 goto destroy_blkring; 1282 } 1283 1284 err = xenbus_printf(xbt, dev->nodename, 1285 "ring-ref", "%u", info->ring_ref); 1286 if (err) { 1287 message = "writing ring-ref"; 1288 goto abort_transaction; 1289 } 1290 err = xenbus_printf(xbt, dev->nodename, 1291 "event-channel", "%u", info->evtchn); 1292 if (err) { 1293 message = "writing event-channel"; 1294 goto abort_transaction; 1295 } 1296 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 1297 XEN_IO_PROTO_ABI_NATIVE); 1298 if (err) { 1299 message = "writing protocol"; 1300 goto abort_transaction; 1301 } 1302 err = xenbus_printf(xbt, dev->nodename, 1303 "feature-persistent", "%u", 1); 1304 if (err) 1305 dev_warn(&dev->dev, 1306 "writing persistent grants feature to xenbus"); 1307 1308 err = xenbus_transaction_end(xbt, 0); 1309 if (err) { 1310 if (err == -EAGAIN) 1311 goto again; 1312 xenbus_dev_fatal(dev, err, "completing transaction"); 1313 goto destroy_blkring; 1314 } 1315 1316 xenbus_switch_state(dev, XenbusStateInitialised); 1317 1318 return 0; 1319 1320 abort_transaction: 1321 xenbus_transaction_end(xbt, 1); 1322 if (message) 1323 xenbus_dev_fatal(dev, err, "%s", message); 1324 destroy_blkring: 1325 blkif_free(info, 0); 1326 out: 1327 return err; 1328 } 1329 1330 /** 1331 * Entry point to this code when a new device is created. Allocate the basic 1332 * structures and the ring buffer for communication with the backend, and 1333 * inform the backend of the appropriate details for those. Switch to 1334 * Initialised state. 1335 */ 1336 static int blkfront_probe(struct xenbus_device *dev, 1337 const struct xenbus_device_id *id) 1338 { 1339 int err, vdevice, i; 1340 struct blkfront_info *info; 1341 1342 /* FIXME: Use dynamic device id if this is not set. */ 1343 err = xenbus_scanf(XBT_NIL, dev->nodename, 1344 "virtual-device", "%i", &vdevice); 1345 if (err != 1) { 1346 /* go looking in the extended area instead */ 1347 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 1348 "%i", &vdevice); 1349 if (err != 1) { 1350 xenbus_dev_fatal(dev, err, "reading virtual-device"); 1351 return err; 1352 } 1353 } 1354 1355 if (xen_hvm_domain()) { 1356 char *type; 1357 int len; 1358 /* no unplug has been done: do not hook devices != xen vbds */ 1359 if (xen_has_pv_and_legacy_disk_devices()) { 1360 int major; 1361 1362 if (!VDEV_IS_EXTENDED(vdevice)) 1363 major = BLKIF_MAJOR(vdevice); 1364 else 1365 major = XENVBD_MAJOR; 1366 1367 if (major != XENVBD_MAJOR) { 1368 printk(KERN_INFO 1369 "%s: HVM does not support vbd %d as xen block device\n", 1370 __FUNCTION__, vdevice); 1371 return -ENODEV; 1372 } 1373 } 1374 /* do not create a PV cdrom device if we are an HVM guest */ 1375 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 1376 if (IS_ERR(type)) 1377 return -ENODEV; 1378 if (strncmp(type, "cdrom", 5) == 0) { 1379 kfree(type); 1380 return -ENODEV; 1381 } 1382 kfree(type); 1383 } 1384 info = kzalloc(sizeof(*info), GFP_KERNEL); 1385 if (!info) { 1386 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 1387 return -ENOMEM; 1388 } 1389 1390 mutex_init(&info->mutex); 1391 spin_lock_init(&info->io_lock); 1392 info->xbdev = dev; 1393 info->vdevice = vdevice; 1394 INIT_LIST_HEAD(&info->grants); 1395 INIT_LIST_HEAD(&info->indirect_pages); 1396 info->persistent_gnts_c = 0; 1397 info->connected = BLKIF_STATE_DISCONNECTED; 1398 INIT_WORK(&info->work, blkif_restart_queue); 1399 1400 for (i = 0; i < BLK_RING_SIZE; i++) 1401 info->shadow[i].req.u.rw.id = i+1; 1402 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1403 1404 /* Front end dir is a number, which is used as the id. */ 1405 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1406 dev_set_drvdata(&dev->dev, info); 1407 1408 err = talk_to_blkback(dev, info); 1409 if (err) { 1410 kfree(info); 1411 dev_set_drvdata(&dev->dev, NULL); 1412 return err; 1413 } 1414 1415 return 0; 1416 } 1417 1418 static void split_bio_end(struct bio *bio, int error) 1419 { 1420 struct split_bio *split_bio = bio->bi_private; 1421 1422 if (error) 1423 split_bio->err = error; 1424 1425 if (atomic_dec_and_test(&split_bio->pending)) { 1426 split_bio->bio->bi_phys_segments = 0; 1427 bio_endio(split_bio->bio, split_bio->err); 1428 kfree(split_bio); 1429 } 1430 bio_put(bio); 1431 } 1432 1433 static int blkif_recover(struct blkfront_info *info) 1434 { 1435 int i; 1436 struct request *req, *n; 1437 struct blk_shadow *copy; 1438 int rc; 1439 struct bio *bio, *cloned_bio; 1440 struct bio_list bio_list, merge_bio; 1441 unsigned int segs, offset; 1442 int pending, size; 1443 struct split_bio *split_bio; 1444 struct list_head requests; 1445 1446 /* Stage 1: Make a safe copy of the shadow state. */ 1447 copy = kmemdup(info->shadow, sizeof(info->shadow), 1448 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); 1449 if (!copy) 1450 return -ENOMEM; 1451 1452 /* Stage 2: Set up free list. */ 1453 memset(&info->shadow, 0, sizeof(info->shadow)); 1454 for (i = 0; i < BLK_RING_SIZE; i++) 1455 info->shadow[i].req.u.rw.id = i+1; 1456 info->shadow_free = info->ring.req_prod_pvt; 1457 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1458 1459 rc = blkfront_setup_indirect(info); 1460 if (rc) { 1461 kfree(copy); 1462 return rc; 1463 } 1464 1465 segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST; 1466 blk_queue_max_segments(info->rq, segs); 1467 bio_list_init(&bio_list); 1468 INIT_LIST_HEAD(&requests); 1469 for (i = 0; i < BLK_RING_SIZE; i++) { 1470 /* Not in use? */ 1471 if (!copy[i].request) 1472 continue; 1473 1474 /* 1475 * Get the bios in the request so we can re-queue them. 1476 */ 1477 if (copy[i].request->cmd_flags & 1478 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1479 /* 1480 * Flush operations don't contain bios, so 1481 * we need to requeue the whole request 1482 */ 1483 list_add(©[i].request->queuelist, &requests); 1484 continue; 1485 } 1486 merge_bio.head = copy[i].request->bio; 1487 merge_bio.tail = copy[i].request->biotail; 1488 bio_list_merge(&bio_list, &merge_bio); 1489 copy[i].request->bio = NULL; 1490 blk_put_request(copy[i].request); 1491 } 1492 1493 kfree(copy); 1494 1495 /* 1496 * Empty the queue, this is important because we might have 1497 * requests in the queue with more segments than what we 1498 * can handle now. 1499 */ 1500 spin_lock_irq(&info->io_lock); 1501 while ((req = blk_fetch_request(info->rq)) != NULL) { 1502 if (req->cmd_flags & 1503 (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) { 1504 list_add(&req->queuelist, &requests); 1505 continue; 1506 } 1507 merge_bio.head = req->bio; 1508 merge_bio.tail = req->biotail; 1509 bio_list_merge(&bio_list, &merge_bio); 1510 req->bio = NULL; 1511 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) 1512 pr_alert("diskcache flush request found!\n"); 1513 __blk_put_request(info->rq, req); 1514 } 1515 spin_unlock_irq(&info->io_lock); 1516 1517 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1518 1519 spin_lock_irq(&info->io_lock); 1520 1521 /* Now safe for us to use the shared ring */ 1522 info->connected = BLKIF_STATE_CONNECTED; 1523 1524 /* Kick any other new requests queued since we resumed */ 1525 kick_pending_request_queues(info); 1526 1527 list_for_each_entry_safe(req, n, &requests, queuelist) { 1528 /* Requeue pending requests (flush or discard) */ 1529 list_del_init(&req->queuelist); 1530 BUG_ON(req->nr_phys_segments > segs); 1531 blk_requeue_request(info->rq, req); 1532 } 1533 spin_unlock_irq(&info->io_lock); 1534 1535 while ((bio = bio_list_pop(&bio_list)) != NULL) { 1536 /* Traverse the list of pending bios and re-queue them */ 1537 if (bio_segments(bio) > segs) { 1538 /* 1539 * This bio has more segments than what we can 1540 * handle, we have to split it. 1541 */ 1542 pending = (bio_segments(bio) + segs - 1) / segs; 1543 split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO); 1544 BUG_ON(split_bio == NULL); 1545 atomic_set(&split_bio->pending, pending); 1546 split_bio->bio = bio; 1547 for (i = 0; i < pending; i++) { 1548 offset = (i * segs * PAGE_SIZE) >> 9; 1549 size = min((unsigned int)(segs * PAGE_SIZE) >> 9, 1550 (unsigned int)bio_sectors(bio) - offset); 1551 cloned_bio = bio_clone(bio, GFP_NOIO); 1552 BUG_ON(cloned_bio == NULL); 1553 bio_trim(cloned_bio, offset, size); 1554 cloned_bio->bi_private = split_bio; 1555 cloned_bio->bi_end_io = split_bio_end; 1556 submit_bio(cloned_bio->bi_rw, cloned_bio); 1557 } 1558 /* 1559 * Now we have to wait for all those smaller bios to 1560 * end, so we can also end the "parent" bio. 1561 */ 1562 continue; 1563 } 1564 /* We don't need to split this bio */ 1565 submit_bio(bio->bi_rw, bio); 1566 } 1567 1568 return 0; 1569 } 1570 1571 /** 1572 * We are reconnecting to the backend, due to a suspend/resume, or a backend 1573 * driver restart. We tear down our blkif structure and recreate it, but 1574 * leave the device-layer structures intact so that this is transparent to the 1575 * rest of the kernel. 1576 */ 1577 static int blkfront_resume(struct xenbus_device *dev) 1578 { 1579 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1580 int err; 1581 1582 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 1583 1584 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 1585 1586 err = talk_to_blkback(dev, info); 1587 1588 /* 1589 * We have to wait for the backend to switch to 1590 * connected state, since we want to read which 1591 * features it supports. 1592 */ 1593 1594 return err; 1595 } 1596 1597 static void 1598 blkfront_closing(struct blkfront_info *info) 1599 { 1600 struct xenbus_device *xbdev = info->xbdev; 1601 struct block_device *bdev = NULL; 1602 1603 mutex_lock(&info->mutex); 1604 1605 if (xbdev->state == XenbusStateClosing) { 1606 mutex_unlock(&info->mutex); 1607 return; 1608 } 1609 1610 if (info->gd) 1611 bdev = bdget_disk(info->gd, 0); 1612 1613 mutex_unlock(&info->mutex); 1614 1615 if (!bdev) { 1616 xenbus_frontend_closed(xbdev); 1617 return; 1618 } 1619 1620 mutex_lock(&bdev->bd_mutex); 1621 1622 if (bdev->bd_openers) { 1623 xenbus_dev_error(xbdev, -EBUSY, 1624 "Device in use; refusing to close"); 1625 xenbus_switch_state(xbdev, XenbusStateClosing); 1626 } else { 1627 xlvbd_release_gendisk(info); 1628 xenbus_frontend_closed(xbdev); 1629 } 1630 1631 mutex_unlock(&bdev->bd_mutex); 1632 bdput(bdev); 1633 } 1634 1635 static void blkfront_setup_discard(struct blkfront_info *info) 1636 { 1637 int err; 1638 char *type; 1639 unsigned int discard_granularity; 1640 unsigned int discard_alignment; 1641 unsigned int discard_secure; 1642 1643 type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL); 1644 if (IS_ERR(type)) 1645 return; 1646 1647 info->feature_secdiscard = 0; 1648 if (strncmp(type, "phy", 3) == 0) { 1649 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1650 "discard-granularity", "%u", &discard_granularity, 1651 "discard-alignment", "%u", &discard_alignment, 1652 NULL); 1653 if (!err) { 1654 info->feature_discard = 1; 1655 info->discard_granularity = discard_granularity; 1656 info->discard_alignment = discard_alignment; 1657 } 1658 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1659 "discard-secure", "%d", &discard_secure, 1660 NULL); 1661 if (!err) 1662 info->feature_secdiscard = discard_secure; 1663 1664 } else if (strncmp(type, "file", 4) == 0) 1665 info->feature_discard = 1; 1666 1667 kfree(type); 1668 } 1669 1670 static int blkfront_setup_indirect(struct blkfront_info *info) 1671 { 1672 unsigned int indirect_segments, segs; 1673 int err, i; 1674 1675 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1676 "feature-max-indirect-segments", "%u", &indirect_segments, 1677 NULL); 1678 if (err) { 1679 info->max_indirect_segments = 0; 1680 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST; 1681 } else { 1682 info->max_indirect_segments = min(indirect_segments, 1683 xen_blkif_max_segments); 1684 segs = info->max_indirect_segments; 1685 } 1686 1687 err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE); 1688 if (err) 1689 goto out_of_memory; 1690 1691 if (!info->feature_persistent && info->max_indirect_segments) { 1692 /* 1693 * We are using indirect descriptors but not persistent 1694 * grants, we need to allocate a set of pages that can be 1695 * used for mapping indirect grefs 1696 */ 1697 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE; 1698 1699 BUG_ON(!list_empty(&info->indirect_pages)); 1700 for (i = 0; i < num; i++) { 1701 struct page *indirect_page = alloc_page(GFP_NOIO); 1702 if (!indirect_page) 1703 goto out_of_memory; 1704 list_add(&indirect_page->lru, &info->indirect_pages); 1705 } 1706 } 1707 1708 for (i = 0; i < BLK_RING_SIZE; i++) { 1709 info->shadow[i].grants_used = kzalloc( 1710 sizeof(info->shadow[i].grants_used[0]) * segs, 1711 GFP_NOIO); 1712 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO); 1713 if (info->max_indirect_segments) 1714 info->shadow[i].indirect_grants = kzalloc( 1715 sizeof(info->shadow[i].indirect_grants[0]) * 1716 INDIRECT_GREFS(segs), 1717 GFP_NOIO); 1718 if ((info->shadow[i].grants_used == NULL) || 1719 (info->shadow[i].sg == NULL) || 1720 (info->max_indirect_segments && 1721 (info->shadow[i].indirect_grants == NULL))) 1722 goto out_of_memory; 1723 sg_init_table(info->shadow[i].sg, segs); 1724 } 1725 1726 1727 return 0; 1728 1729 out_of_memory: 1730 for (i = 0; i < BLK_RING_SIZE; i++) { 1731 kfree(info->shadow[i].grants_used); 1732 info->shadow[i].grants_used = NULL; 1733 kfree(info->shadow[i].sg); 1734 info->shadow[i].sg = NULL; 1735 kfree(info->shadow[i].indirect_grants); 1736 info->shadow[i].indirect_grants = NULL; 1737 } 1738 if (!list_empty(&info->indirect_pages)) { 1739 struct page *indirect_page, *n; 1740 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) { 1741 list_del(&indirect_page->lru); 1742 __free_page(indirect_page); 1743 } 1744 } 1745 return -ENOMEM; 1746 } 1747 1748 /* 1749 * Invoked when the backend is finally 'ready' (and has told produced 1750 * the details about the physical device - #sectors, size, etc). 1751 */ 1752 static void blkfront_connect(struct blkfront_info *info) 1753 { 1754 unsigned long long sectors; 1755 unsigned long sector_size; 1756 unsigned int physical_sector_size; 1757 unsigned int binfo; 1758 int err; 1759 int barrier, flush, discard, persistent; 1760 1761 switch (info->connected) { 1762 case BLKIF_STATE_CONNECTED: 1763 /* 1764 * Potentially, the back-end may be signalling 1765 * a capacity change; update the capacity. 1766 */ 1767 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1768 "sectors", "%Lu", §ors); 1769 if (XENBUS_EXIST_ERR(err)) 1770 return; 1771 printk(KERN_INFO "Setting capacity to %Lu\n", 1772 sectors); 1773 set_capacity(info->gd, sectors); 1774 revalidate_disk(info->gd); 1775 1776 return; 1777 case BLKIF_STATE_SUSPENDED: 1778 /* 1779 * If we are recovering from suspension, we need to wait 1780 * for the backend to announce it's features before 1781 * reconnecting, at least we need to know if the backend 1782 * supports indirect descriptors, and how many. 1783 */ 1784 blkif_recover(info); 1785 return; 1786 1787 default: 1788 break; 1789 } 1790 1791 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 1792 __func__, info->xbdev->otherend); 1793 1794 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1795 "sectors", "%llu", §ors, 1796 "info", "%u", &binfo, 1797 "sector-size", "%lu", §or_size, 1798 NULL); 1799 if (err) { 1800 xenbus_dev_fatal(info->xbdev, err, 1801 "reading backend fields at %s", 1802 info->xbdev->otherend); 1803 return; 1804 } 1805 1806 /* 1807 * physcial-sector-size is a newer field, so old backends may not 1808 * provide this. Assume physical sector size to be the same as 1809 * sector_size in that case. 1810 */ 1811 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1812 "physical-sector-size", "%u", &physical_sector_size); 1813 if (err != 1) 1814 physical_sector_size = sector_size; 1815 1816 info->feature_flush = 0; 1817 info->flush_op = 0; 1818 1819 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1820 "feature-barrier", "%d", &barrier, 1821 NULL); 1822 1823 /* 1824 * If there's no "feature-barrier" defined, then it means 1825 * we're dealing with a very old backend which writes 1826 * synchronously; nothing to do. 1827 * 1828 * If there are barriers, then we use flush. 1829 */ 1830 if (!err && barrier) { 1831 info->feature_flush = REQ_FLUSH | REQ_FUA; 1832 info->flush_op = BLKIF_OP_WRITE_BARRIER; 1833 } 1834 /* 1835 * And if there is "feature-flush-cache" use that above 1836 * barriers. 1837 */ 1838 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1839 "feature-flush-cache", "%d", &flush, 1840 NULL); 1841 1842 if (!err && flush) { 1843 info->feature_flush = REQ_FLUSH; 1844 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE; 1845 } 1846 1847 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1848 "feature-discard", "%d", &discard, 1849 NULL); 1850 1851 if (!err && discard) 1852 blkfront_setup_discard(info); 1853 1854 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1855 "feature-persistent", "%u", &persistent, 1856 NULL); 1857 if (err) 1858 info->feature_persistent = 0; 1859 else 1860 info->feature_persistent = persistent; 1861 1862 err = blkfront_setup_indirect(info); 1863 if (err) { 1864 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s", 1865 info->xbdev->otherend); 1866 return; 1867 } 1868 1869 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size, 1870 physical_sector_size); 1871 if (err) { 1872 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 1873 info->xbdev->otherend); 1874 return; 1875 } 1876 1877 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1878 1879 /* Kick pending requests. */ 1880 spin_lock_irq(&info->io_lock); 1881 info->connected = BLKIF_STATE_CONNECTED; 1882 kick_pending_request_queues(info); 1883 spin_unlock_irq(&info->io_lock); 1884 1885 add_disk(info->gd); 1886 1887 info->is_ready = 1; 1888 } 1889 1890 /** 1891 * Callback received when the backend's state changes. 1892 */ 1893 static void blkback_changed(struct xenbus_device *dev, 1894 enum xenbus_state backend_state) 1895 { 1896 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1897 1898 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 1899 1900 switch (backend_state) { 1901 case XenbusStateInitialising: 1902 case XenbusStateInitWait: 1903 case XenbusStateInitialised: 1904 case XenbusStateReconfiguring: 1905 case XenbusStateReconfigured: 1906 case XenbusStateUnknown: 1907 break; 1908 1909 case XenbusStateConnected: 1910 blkfront_connect(info); 1911 break; 1912 1913 case XenbusStateClosed: 1914 if (dev->state == XenbusStateClosed) 1915 break; 1916 /* Missed the backend's Closing state -- fallthrough */ 1917 case XenbusStateClosing: 1918 blkfront_closing(info); 1919 break; 1920 } 1921 } 1922 1923 static int blkfront_remove(struct xenbus_device *xbdev) 1924 { 1925 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 1926 struct block_device *bdev = NULL; 1927 struct gendisk *disk; 1928 1929 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 1930 1931 blkif_free(info, 0); 1932 1933 mutex_lock(&info->mutex); 1934 1935 disk = info->gd; 1936 if (disk) 1937 bdev = bdget_disk(disk, 0); 1938 1939 info->xbdev = NULL; 1940 mutex_unlock(&info->mutex); 1941 1942 if (!bdev) { 1943 kfree(info); 1944 return 0; 1945 } 1946 1947 /* 1948 * The xbdev was removed before we reached the Closed 1949 * state. See if it's safe to remove the disk. If the bdev 1950 * isn't closed yet, we let release take care of it. 1951 */ 1952 1953 mutex_lock(&bdev->bd_mutex); 1954 info = disk->private_data; 1955 1956 dev_warn(disk_to_dev(disk), 1957 "%s was hot-unplugged, %d stale handles\n", 1958 xbdev->nodename, bdev->bd_openers); 1959 1960 if (info && !bdev->bd_openers) { 1961 xlvbd_release_gendisk(info); 1962 disk->private_data = NULL; 1963 kfree(info); 1964 } 1965 1966 mutex_unlock(&bdev->bd_mutex); 1967 bdput(bdev); 1968 1969 return 0; 1970 } 1971 1972 static int blkfront_is_ready(struct xenbus_device *dev) 1973 { 1974 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1975 1976 return info->is_ready && info->xbdev; 1977 } 1978 1979 static int blkif_open(struct block_device *bdev, fmode_t mode) 1980 { 1981 struct gendisk *disk = bdev->bd_disk; 1982 struct blkfront_info *info; 1983 int err = 0; 1984 1985 mutex_lock(&blkfront_mutex); 1986 1987 info = disk->private_data; 1988 if (!info) { 1989 /* xbdev gone */ 1990 err = -ERESTARTSYS; 1991 goto out; 1992 } 1993 1994 mutex_lock(&info->mutex); 1995 1996 if (!info->gd) 1997 /* xbdev is closed */ 1998 err = -ERESTARTSYS; 1999 2000 mutex_unlock(&info->mutex); 2001 2002 out: 2003 mutex_unlock(&blkfront_mutex); 2004 return err; 2005 } 2006 2007 static void blkif_release(struct gendisk *disk, fmode_t mode) 2008 { 2009 struct blkfront_info *info = disk->private_data; 2010 struct block_device *bdev; 2011 struct xenbus_device *xbdev; 2012 2013 mutex_lock(&blkfront_mutex); 2014 2015 bdev = bdget_disk(disk, 0); 2016 2017 if (!bdev) { 2018 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name); 2019 goto out_mutex; 2020 } 2021 if (bdev->bd_openers) 2022 goto out; 2023 2024 /* 2025 * Check if we have been instructed to close. We will have 2026 * deferred this request, because the bdev was still open. 2027 */ 2028 2029 mutex_lock(&info->mutex); 2030 xbdev = info->xbdev; 2031 2032 if (xbdev && xbdev->state == XenbusStateClosing) { 2033 /* pending switch to state closed */ 2034 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2035 xlvbd_release_gendisk(info); 2036 xenbus_frontend_closed(info->xbdev); 2037 } 2038 2039 mutex_unlock(&info->mutex); 2040 2041 if (!xbdev) { 2042 /* sudden device removal */ 2043 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 2044 xlvbd_release_gendisk(info); 2045 disk->private_data = NULL; 2046 kfree(info); 2047 } 2048 2049 out: 2050 bdput(bdev); 2051 out_mutex: 2052 mutex_unlock(&blkfront_mutex); 2053 } 2054 2055 static const struct block_device_operations xlvbd_block_fops = 2056 { 2057 .owner = THIS_MODULE, 2058 .open = blkif_open, 2059 .release = blkif_release, 2060 .getgeo = blkif_getgeo, 2061 .ioctl = blkif_ioctl, 2062 }; 2063 2064 2065 static const struct xenbus_device_id blkfront_ids[] = { 2066 { "vbd" }, 2067 { "" } 2068 }; 2069 2070 static DEFINE_XENBUS_DRIVER(blkfront, , 2071 .probe = blkfront_probe, 2072 .remove = blkfront_remove, 2073 .resume = blkfront_resume, 2074 .otherend_changed = blkback_changed, 2075 .is_ready = blkfront_is_ready, 2076 ); 2077 2078 static int __init xlblk_init(void) 2079 { 2080 int ret; 2081 2082 if (!xen_domain()) 2083 return -ENODEV; 2084 2085 if (!xen_has_pv_disk_devices()) 2086 return -ENODEV; 2087 2088 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 2089 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 2090 XENVBD_MAJOR, DEV_NAME); 2091 return -ENODEV; 2092 } 2093 2094 ret = xenbus_register_frontend(&blkfront_driver); 2095 if (ret) { 2096 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2097 return ret; 2098 } 2099 2100 return 0; 2101 } 2102 module_init(xlblk_init); 2103 2104 2105 static void __exit xlblk_exit(void) 2106 { 2107 xenbus_unregister_driver(&blkfront_driver); 2108 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 2109 kfree(minors); 2110 } 2111 module_exit(xlblk_exit); 2112 2113 MODULE_DESCRIPTION("Xen virtual block device frontend"); 2114 MODULE_LICENSE("GPL"); 2115 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 2116 MODULE_ALIAS("xen:vbd"); 2117 MODULE_ALIAS("xenblk"); 2118