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 47 #include <xen/xen.h> 48 #include <xen/xenbus.h> 49 #include <xen/grant_table.h> 50 #include <xen/events.h> 51 #include <xen/page.h> 52 #include <xen/platform_pci.h> 53 54 #include <xen/interface/grant_table.h> 55 #include <xen/interface/io/blkif.h> 56 #include <xen/interface/io/protocols.h> 57 58 #include <asm/xen/hypervisor.h> 59 60 enum blkif_state { 61 BLKIF_STATE_DISCONNECTED, 62 BLKIF_STATE_CONNECTED, 63 BLKIF_STATE_SUSPENDED, 64 }; 65 66 struct blk_shadow { 67 struct blkif_request req; 68 struct request *request; 69 unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 70 }; 71 72 static DEFINE_MUTEX(blkfront_mutex); 73 static const struct block_device_operations xlvbd_block_fops; 74 75 #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE) 76 77 /* 78 * We have one of these per vbd, whether ide, scsi or 'other'. They 79 * hang in private_data off the gendisk structure. We may end up 80 * putting all kinds of interesting stuff here :-) 81 */ 82 struct blkfront_info 83 { 84 struct mutex mutex; 85 struct xenbus_device *xbdev; 86 struct gendisk *gd; 87 int vdevice; 88 blkif_vdev_t handle; 89 enum blkif_state connected; 90 int ring_ref; 91 struct blkif_front_ring ring; 92 struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST]; 93 unsigned int evtchn, irq; 94 struct request_queue *rq; 95 struct work_struct work; 96 struct gnttab_free_callback callback; 97 struct blk_shadow shadow[BLK_RING_SIZE]; 98 unsigned long shadow_free; 99 unsigned int feature_flush; 100 unsigned int flush_op; 101 unsigned int feature_discard:1; 102 unsigned int feature_secdiscard:1; 103 unsigned int discard_granularity; 104 unsigned int discard_alignment; 105 int is_ready; 106 }; 107 108 static DEFINE_SPINLOCK(blkif_io_lock); 109 110 static unsigned int nr_minors; 111 static unsigned long *minors; 112 static DEFINE_SPINLOCK(minor_lock); 113 114 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \ 115 (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE) 116 #define GRANT_INVALID_REF 0 117 118 #define PARTS_PER_DISK 16 119 #define PARTS_PER_EXT_DISK 256 120 121 #define BLKIF_MAJOR(dev) ((dev)>>8) 122 #define BLKIF_MINOR(dev) ((dev) & 0xff) 123 124 #define EXT_SHIFT 28 125 #define EXTENDED (1<<EXT_SHIFT) 126 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED)) 127 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED)) 128 #define EMULATED_HD_DISK_MINOR_OFFSET (0) 129 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256) 130 #define EMULATED_SD_DISK_MINOR_OFFSET (0) 131 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256) 132 133 #define DEV_NAME "xvd" /* name in /dev */ 134 135 static int get_id_from_freelist(struct blkfront_info *info) 136 { 137 unsigned long free = info->shadow_free; 138 BUG_ON(free >= BLK_RING_SIZE); 139 info->shadow_free = info->shadow[free].req.u.rw.id; 140 info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */ 141 return free; 142 } 143 144 static void add_id_to_freelist(struct blkfront_info *info, 145 unsigned long id) 146 { 147 info->shadow[id].req.u.rw.id = info->shadow_free; 148 info->shadow[id].request = NULL; 149 info->shadow_free = id; 150 } 151 152 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr) 153 { 154 unsigned int end = minor + nr; 155 int rc; 156 157 if (end > nr_minors) { 158 unsigned long *bitmap, *old; 159 160 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap), 161 GFP_KERNEL); 162 if (bitmap == NULL) 163 return -ENOMEM; 164 165 spin_lock(&minor_lock); 166 if (end > nr_minors) { 167 old = minors; 168 memcpy(bitmap, minors, 169 BITS_TO_LONGS(nr_minors) * sizeof(*bitmap)); 170 minors = bitmap; 171 nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG; 172 } else 173 old = bitmap; 174 spin_unlock(&minor_lock); 175 kfree(old); 176 } 177 178 spin_lock(&minor_lock); 179 if (find_next_bit(minors, end, minor) >= end) { 180 for (; minor < end; ++minor) 181 __set_bit(minor, minors); 182 rc = 0; 183 } else 184 rc = -EBUSY; 185 spin_unlock(&minor_lock); 186 187 return rc; 188 } 189 190 static void xlbd_release_minors(unsigned int minor, unsigned int nr) 191 { 192 unsigned int end = minor + nr; 193 194 BUG_ON(end > nr_minors); 195 spin_lock(&minor_lock); 196 for (; minor < end; ++minor) 197 __clear_bit(minor, minors); 198 spin_unlock(&minor_lock); 199 } 200 201 static void blkif_restart_queue_callback(void *arg) 202 { 203 struct blkfront_info *info = (struct blkfront_info *)arg; 204 schedule_work(&info->work); 205 } 206 207 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg) 208 { 209 /* We don't have real geometry info, but let's at least return 210 values consistent with the size of the device */ 211 sector_t nsect = get_capacity(bd->bd_disk); 212 sector_t cylinders = nsect; 213 214 hg->heads = 0xff; 215 hg->sectors = 0x3f; 216 sector_div(cylinders, hg->heads * hg->sectors); 217 hg->cylinders = cylinders; 218 if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect) 219 hg->cylinders = 0xffff; 220 return 0; 221 } 222 223 static int blkif_ioctl(struct block_device *bdev, fmode_t mode, 224 unsigned command, unsigned long argument) 225 { 226 struct blkfront_info *info = bdev->bd_disk->private_data; 227 int i; 228 229 dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n", 230 command, (long)argument); 231 232 switch (command) { 233 case CDROMMULTISESSION: 234 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n"); 235 for (i = 0; i < sizeof(struct cdrom_multisession); i++) 236 if (put_user(0, (char __user *)(argument + i))) 237 return -EFAULT; 238 return 0; 239 240 case CDROM_GET_CAPABILITY: { 241 struct gendisk *gd = info->gd; 242 if (gd->flags & GENHD_FL_CD) 243 return 0; 244 return -EINVAL; 245 } 246 247 default: 248 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n", 249 command);*/ 250 return -EINVAL; /* same return as native Linux */ 251 } 252 253 return 0; 254 } 255 256 /* 257 * Generate a Xen blkfront IO request from a blk layer request. Reads 258 * and writes are handled as expected. 259 * 260 * @req: a request struct 261 */ 262 static int blkif_queue_request(struct request *req) 263 { 264 struct blkfront_info *info = req->rq_disk->private_data; 265 unsigned long buffer_mfn; 266 struct blkif_request *ring_req; 267 unsigned long id; 268 unsigned int fsect, lsect; 269 int i, ref; 270 grant_ref_t gref_head; 271 struct scatterlist *sg; 272 273 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) 274 return 1; 275 276 if (gnttab_alloc_grant_references( 277 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) { 278 gnttab_request_free_callback( 279 &info->callback, 280 blkif_restart_queue_callback, 281 info, 282 BLKIF_MAX_SEGMENTS_PER_REQUEST); 283 return 1; 284 } 285 286 /* Fill out a communications ring structure. */ 287 ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); 288 id = get_id_from_freelist(info); 289 info->shadow[id].request = req; 290 291 ring_req->u.rw.id = id; 292 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req); 293 ring_req->u.rw.handle = info->handle; 294 295 ring_req->operation = rq_data_dir(req) ? 296 BLKIF_OP_WRITE : BLKIF_OP_READ; 297 298 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) { 299 /* 300 * Ideally we can do an unordered flush-to-disk. In case the 301 * backend onlysupports barriers, use that. A barrier request 302 * a superset of FUA, so we can implement it the same 303 * way. (It's also a FLUSH+FUA, since it is 304 * guaranteed ordered WRT previous writes.) 305 */ 306 ring_req->operation = info->flush_op; 307 } 308 309 if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) { 310 /* id, sector_number and handle are set above. */ 311 ring_req->operation = BLKIF_OP_DISCARD; 312 ring_req->u.discard.nr_sectors = blk_rq_sectors(req); 313 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard) 314 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE; 315 else 316 ring_req->u.discard.flag = 0; 317 } else { 318 ring_req->u.rw.nr_segments = blk_rq_map_sg(req->q, req, 319 info->sg); 320 BUG_ON(ring_req->u.rw.nr_segments > 321 BLKIF_MAX_SEGMENTS_PER_REQUEST); 322 323 for_each_sg(info->sg, sg, ring_req->u.rw.nr_segments, i) { 324 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg))); 325 fsect = sg->offset >> 9; 326 lsect = fsect + (sg->length >> 9) - 1; 327 /* install a grant reference. */ 328 ref = gnttab_claim_grant_reference(&gref_head); 329 BUG_ON(ref == -ENOSPC); 330 331 gnttab_grant_foreign_access_ref( 332 ref, 333 info->xbdev->otherend_id, 334 buffer_mfn, 335 rq_data_dir(req)); 336 337 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn); 338 ring_req->u.rw.seg[i] = 339 (struct blkif_request_segment) { 340 .gref = ref, 341 .first_sect = fsect, 342 .last_sect = lsect }; 343 } 344 } 345 346 info->ring.req_prod_pvt++; 347 348 /* Keep a private copy so we can reissue requests when recovering. */ 349 info->shadow[id].req = *ring_req; 350 351 gnttab_free_grant_references(gref_head); 352 353 return 0; 354 } 355 356 357 static inline void flush_requests(struct blkfront_info *info) 358 { 359 int notify; 360 361 RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify); 362 363 if (notify) 364 notify_remote_via_irq(info->irq); 365 } 366 367 /* 368 * do_blkif_request 369 * read a block; request is in a request queue 370 */ 371 static void do_blkif_request(struct request_queue *rq) 372 { 373 struct blkfront_info *info = NULL; 374 struct request *req; 375 int queued; 376 377 pr_debug("Entered do_blkif_request\n"); 378 379 queued = 0; 380 381 while ((req = blk_peek_request(rq)) != NULL) { 382 info = req->rq_disk->private_data; 383 384 if (RING_FULL(&info->ring)) 385 goto wait; 386 387 blk_start_request(req); 388 389 if ((req->cmd_type != REQ_TYPE_FS) || 390 ((req->cmd_flags & (REQ_FLUSH | REQ_FUA)) && 391 !info->flush_op)) { 392 __blk_end_request_all(req, -EIO); 393 continue; 394 } 395 396 pr_debug("do_blk_req %p: cmd %p, sec %lx, " 397 "(%u/%u) buffer:%p [%s]\n", 398 req, req->cmd, (unsigned long)blk_rq_pos(req), 399 blk_rq_cur_sectors(req), blk_rq_sectors(req), 400 req->buffer, rq_data_dir(req) ? "write" : "read"); 401 402 if (blkif_queue_request(req)) { 403 blk_requeue_request(rq, req); 404 wait: 405 /* Avoid pointless unplugs. */ 406 blk_stop_queue(rq); 407 break; 408 } 409 410 queued++; 411 } 412 413 if (queued != 0) 414 flush_requests(info); 415 } 416 417 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size) 418 { 419 struct request_queue *rq; 420 struct blkfront_info *info = gd->private_data; 421 422 rq = blk_init_queue(do_blkif_request, &blkif_io_lock); 423 if (rq == NULL) 424 return -1; 425 426 queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq); 427 428 if (info->feature_discard) { 429 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq); 430 blk_queue_max_discard_sectors(rq, get_capacity(gd)); 431 rq->limits.discard_granularity = info->discard_granularity; 432 rq->limits.discard_alignment = info->discard_alignment; 433 if (info->feature_secdiscard) 434 queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq); 435 } 436 437 /* Hard sector size and max sectors impersonate the equiv. hardware. */ 438 blk_queue_logical_block_size(rq, sector_size); 439 blk_queue_max_hw_sectors(rq, 512); 440 441 /* Each segment in a request is up to an aligned page in size. */ 442 blk_queue_segment_boundary(rq, PAGE_SIZE - 1); 443 blk_queue_max_segment_size(rq, PAGE_SIZE); 444 445 /* Ensure a merged request will fit in a single I/O ring slot. */ 446 blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST); 447 448 /* Make sure buffer addresses are sector-aligned. */ 449 blk_queue_dma_alignment(rq, 511); 450 451 /* Make sure we don't use bounce buffers. */ 452 blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY); 453 454 gd->queue = rq; 455 456 return 0; 457 } 458 459 460 static void xlvbd_flush(struct blkfront_info *info) 461 { 462 blk_queue_flush(info->rq, info->feature_flush); 463 printk(KERN_INFO "blkfront: %s: %s: %s\n", 464 info->gd->disk_name, 465 info->flush_op == BLKIF_OP_WRITE_BARRIER ? 466 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ? 467 "flush diskcache" : "barrier or flush"), 468 info->feature_flush ? "enabled" : "disabled"); 469 } 470 471 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset) 472 { 473 int major; 474 major = BLKIF_MAJOR(vdevice); 475 *minor = BLKIF_MINOR(vdevice); 476 switch (major) { 477 case XEN_IDE0_MAJOR: 478 *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET; 479 *minor = ((*minor / 64) * PARTS_PER_DISK) + 480 EMULATED_HD_DISK_MINOR_OFFSET; 481 break; 482 case XEN_IDE1_MAJOR: 483 *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET; 484 *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) + 485 EMULATED_HD_DISK_MINOR_OFFSET; 486 break; 487 case XEN_SCSI_DISK0_MAJOR: 488 *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET; 489 *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET; 490 break; 491 case XEN_SCSI_DISK1_MAJOR: 492 case XEN_SCSI_DISK2_MAJOR: 493 case XEN_SCSI_DISK3_MAJOR: 494 case XEN_SCSI_DISK4_MAJOR: 495 case XEN_SCSI_DISK5_MAJOR: 496 case XEN_SCSI_DISK6_MAJOR: 497 case XEN_SCSI_DISK7_MAJOR: 498 *offset = (*minor / PARTS_PER_DISK) + 499 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) + 500 EMULATED_SD_DISK_NAME_OFFSET; 501 *minor = *minor + 502 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) + 503 EMULATED_SD_DISK_MINOR_OFFSET; 504 break; 505 case XEN_SCSI_DISK8_MAJOR: 506 case XEN_SCSI_DISK9_MAJOR: 507 case XEN_SCSI_DISK10_MAJOR: 508 case XEN_SCSI_DISK11_MAJOR: 509 case XEN_SCSI_DISK12_MAJOR: 510 case XEN_SCSI_DISK13_MAJOR: 511 case XEN_SCSI_DISK14_MAJOR: 512 case XEN_SCSI_DISK15_MAJOR: 513 *offset = (*minor / PARTS_PER_DISK) + 514 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) + 515 EMULATED_SD_DISK_NAME_OFFSET; 516 *minor = *minor + 517 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) + 518 EMULATED_SD_DISK_MINOR_OFFSET; 519 break; 520 case XENVBD_MAJOR: 521 *offset = *minor / PARTS_PER_DISK; 522 break; 523 default: 524 printk(KERN_WARNING "blkfront: your disk configuration is " 525 "incorrect, please use an xvd device instead\n"); 526 return -ENODEV; 527 } 528 return 0; 529 } 530 531 static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 532 struct blkfront_info *info, 533 u16 vdisk_info, u16 sector_size) 534 { 535 struct gendisk *gd; 536 int nr_minors = 1; 537 int err; 538 unsigned int offset; 539 int minor; 540 int nr_parts; 541 542 BUG_ON(info->gd != NULL); 543 BUG_ON(info->rq != NULL); 544 545 if ((info->vdevice>>EXT_SHIFT) > 1) { 546 /* this is above the extended range; something is wrong */ 547 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice); 548 return -ENODEV; 549 } 550 551 if (!VDEV_IS_EXTENDED(info->vdevice)) { 552 err = xen_translate_vdev(info->vdevice, &minor, &offset); 553 if (err) 554 return err; 555 nr_parts = PARTS_PER_DISK; 556 } else { 557 minor = BLKIF_MINOR_EXT(info->vdevice); 558 nr_parts = PARTS_PER_EXT_DISK; 559 offset = minor / nr_parts; 560 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4) 561 printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with " 562 "emulated IDE disks,\n\t choose an xvd device name" 563 "from xvde on\n", info->vdevice); 564 } 565 err = -ENODEV; 566 567 if ((minor % nr_parts) == 0) 568 nr_minors = nr_parts; 569 570 err = xlbd_reserve_minors(minor, nr_minors); 571 if (err) 572 goto out; 573 err = -ENODEV; 574 575 gd = alloc_disk(nr_minors); 576 if (gd == NULL) 577 goto release; 578 579 if (nr_minors > 1) { 580 if (offset < 26) 581 sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset); 582 else 583 sprintf(gd->disk_name, "%s%c%c", DEV_NAME, 584 'a' + ((offset / 26)-1), 'a' + (offset % 26)); 585 } else { 586 if (offset < 26) 587 sprintf(gd->disk_name, "%s%c%d", DEV_NAME, 588 'a' + offset, 589 minor & (nr_parts - 1)); 590 else 591 sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME, 592 'a' + ((offset / 26) - 1), 593 'a' + (offset % 26), 594 minor & (nr_parts - 1)); 595 } 596 597 gd->major = XENVBD_MAJOR; 598 gd->first_minor = minor; 599 gd->fops = &xlvbd_block_fops; 600 gd->private_data = info; 601 gd->driverfs_dev = &(info->xbdev->dev); 602 set_capacity(gd, capacity); 603 604 if (xlvbd_init_blk_queue(gd, sector_size)) { 605 del_gendisk(gd); 606 goto release; 607 } 608 609 info->rq = gd->queue; 610 info->gd = gd; 611 612 xlvbd_flush(info); 613 614 if (vdisk_info & VDISK_READONLY) 615 set_disk_ro(gd, 1); 616 617 if (vdisk_info & VDISK_REMOVABLE) 618 gd->flags |= GENHD_FL_REMOVABLE; 619 620 if (vdisk_info & VDISK_CDROM) 621 gd->flags |= GENHD_FL_CD; 622 623 return 0; 624 625 release: 626 xlbd_release_minors(minor, nr_minors); 627 out: 628 return err; 629 } 630 631 static void xlvbd_release_gendisk(struct blkfront_info *info) 632 { 633 unsigned int minor, nr_minors; 634 unsigned long flags; 635 636 if (info->rq == NULL) 637 return; 638 639 spin_lock_irqsave(&blkif_io_lock, flags); 640 641 /* No more blkif_request(). */ 642 blk_stop_queue(info->rq); 643 644 /* No more gnttab callback work. */ 645 gnttab_cancel_free_callback(&info->callback); 646 spin_unlock_irqrestore(&blkif_io_lock, flags); 647 648 /* Flush gnttab callback work. Must be done with no locks held. */ 649 flush_work_sync(&info->work); 650 651 del_gendisk(info->gd); 652 653 minor = info->gd->first_minor; 654 nr_minors = info->gd->minors; 655 xlbd_release_minors(minor, nr_minors); 656 657 blk_cleanup_queue(info->rq); 658 info->rq = NULL; 659 660 put_disk(info->gd); 661 info->gd = NULL; 662 } 663 664 static void kick_pending_request_queues(struct blkfront_info *info) 665 { 666 if (!RING_FULL(&info->ring)) { 667 /* Re-enable calldowns. */ 668 blk_start_queue(info->rq); 669 /* Kick things off immediately. */ 670 do_blkif_request(info->rq); 671 } 672 } 673 674 static void blkif_restart_queue(struct work_struct *work) 675 { 676 struct blkfront_info *info = container_of(work, struct blkfront_info, work); 677 678 spin_lock_irq(&blkif_io_lock); 679 if (info->connected == BLKIF_STATE_CONNECTED) 680 kick_pending_request_queues(info); 681 spin_unlock_irq(&blkif_io_lock); 682 } 683 684 static void blkif_free(struct blkfront_info *info, int suspend) 685 { 686 /* Prevent new requests being issued until we fix things up. */ 687 spin_lock_irq(&blkif_io_lock); 688 info->connected = suspend ? 689 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED; 690 /* No more blkif_request(). */ 691 if (info->rq) 692 blk_stop_queue(info->rq); 693 /* No more gnttab callback work. */ 694 gnttab_cancel_free_callback(&info->callback); 695 spin_unlock_irq(&blkif_io_lock); 696 697 /* Flush gnttab callback work. Must be done with no locks held. */ 698 flush_work_sync(&info->work); 699 700 /* Free resources associated with old device channel. */ 701 if (info->ring_ref != GRANT_INVALID_REF) { 702 gnttab_end_foreign_access(info->ring_ref, 0, 703 (unsigned long)info->ring.sring); 704 info->ring_ref = GRANT_INVALID_REF; 705 info->ring.sring = NULL; 706 } 707 if (info->irq) 708 unbind_from_irqhandler(info->irq, info); 709 info->evtchn = info->irq = 0; 710 711 } 712 713 static void blkif_completion(struct blk_shadow *s) 714 { 715 int i; 716 /* Do not let BLKIF_OP_DISCARD as nr_segment is in the same place 717 * flag. */ 718 for (i = 0; i < s->req.u.rw.nr_segments; i++) 719 gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL); 720 } 721 722 static irqreturn_t blkif_interrupt(int irq, void *dev_id) 723 { 724 struct request *req; 725 struct blkif_response *bret; 726 RING_IDX i, rp; 727 unsigned long flags; 728 struct blkfront_info *info = (struct blkfront_info *)dev_id; 729 int error; 730 731 spin_lock_irqsave(&blkif_io_lock, flags); 732 733 if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) { 734 spin_unlock_irqrestore(&blkif_io_lock, flags); 735 return IRQ_HANDLED; 736 } 737 738 again: 739 rp = info->ring.sring->rsp_prod; 740 rmb(); /* Ensure we see queued responses up to 'rp'. */ 741 742 for (i = info->ring.rsp_cons; i != rp; i++) { 743 unsigned long id; 744 745 bret = RING_GET_RESPONSE(&info->ring, i); 746 id = bret->id; 747 req = info->shadow[id].request; 748 749 if (bret->operation != BLKIF_OP_DISCARD) 750 blkif_completion(&info->shadow[id]); 751 752 add_id_to_freelist(info, id); 753 754 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO; 755 switch (bret->operation) { 756 case BLKIF_OP_DISCARD: 757 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 758 struct request_queue *rq = info->rq; 759 printk(KERN_WARNING "blkfront: %s: discard op failed\n", 760 info->gd->disk_name); 761 error = -EOPNOTSUPP; 762 info->feature_discard = 0; 763 info->feature_secdiscard = 0; 764 queue_flag_clear(QUEUE_FLAG_DISCARD, rq); 765 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq); 766 } 767 __blk_end_request_all(req, error); 768 break; 769 case BLKIF_OP_FLUSH_DISKCACHE: 770 case BLKIF_OP_WRITE_BARRIER: 771 if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) { 772 printk(KERN_WARNING "blkfront: %s: write %s op failed\n", 773 info->flush_op == BLKIF_OP_WRITE_BARRIER ? 774 "barrier" : "flush disk cache", 775 info->gd->disk_name); 776 error = -EOPNOTSUPP; 777 } 778 if (unlikely(bret->status == BLKIF_RSP_ERROR && 779 info->shadow[id].req.u.rw.nr_segments == 0)) { 780 printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n", 781 info->flush_op == BLKIF_OP_WRITE_BARRIER ? 782 "barrier" : "flush disk cache", 783 info->gd->disk_name); 784 error = -EOPNOTSUPP; 785 } 786 if (unlikely(error)) { 787 if (error == -EOPNOTSUPP) 788 error = 0; 789 info->feature_flush = 0; 790 info->flush_op = 0; 791 xlvbd_flush(info); 792 } 793 /* fall through */ 794 case BLKIF_OP_READ: 795 case BLKIF_OP_WRITE: 796 if (unlikely(bret->status != BLKIF_RSP_OKAY)) 797 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data " 798 "request: %x\n", bret->status); 799 800 __blk_end_request_all(req, error); 801 break; 802 default: 803 BUG(); 804 } 805 } 806 807 info->ring.rsp_cons = i; 808 809 if (i != info->ring.req_prod_pvt) { 810 int more_to_do; 811 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do); 812 if (more_to_do) 813 goto again; 814 } else 815 info->ring.sring->rsp_event = i + 1; 816 817 kick_pending_request_queues(info); 818 819 spin_unlock_irqrestore(&blkif_io_lock, flags); 820 821 return IRQ_HANDLED; 822 } 823 824 825 static int setup_blkring(struct xenbus_device *dev, 826 struct blkfront_info *info) 827 { 828 struct blkif_sring *sring; 829 int err; 830 831 info->ring_ref = GRANT_INVALID_REF; 832 833 sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH); 834 if (!sring) { 835 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring"); 836 return -ENOMEM; 837 } 838 SHARED_RING_INIT(sring); 839 FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE); 840 841 sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST); 842 843 err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring)); 844 if (err < 0) { 845 free_page((unsigned long)sring); 846 info->ring.sring = NULL; 847 goto fail; 848 } 849 info->ring_ref = err; 850 851 err = xenbus_alloc_evtchn(dev, &info->evtchn); 852 if (err) 853 goto fail; 854 855 err = bind_evtchn_to_irqhandler(info->evtchn, 856 blkif_interrupt, 857 IRQF_SAMPLE_RANDOM, "blkif", info); 858 if (err <= 0) { 859 xenbus_dev_fatal(dev, err, 860 "bind_evtchn_to_irqhandler failed"); 861 goto fail; 862 } 863 info->irq = err; 864 865 return 0; 866 fail: 867 blkif_free(info, 0); 868 return err; 869 } 870 871 872 /* Common code used when first setting up, and when resuming. */ 873 static int talk_to_blkback(struct xenbus_device *dev, 874 struct blkfront_info *info) 875 { 876 const char *message = NULL; 877 struct xenbus_transaction xbt; 878 int err; 879 880 /* Create shared ring, alloc event channel. */ 881 err = setup_blkring(dev, info); 882 if (err) 883 goto out; 884 885 again: 886 err = xenbus_transaction_start(&xbt); 887 if (err) { 888 xenbus_dev_fatal(dev, err, "starting transaction"); 889 goto destroy_blkring; 890 } 891 892 err = xenbus_printf(xbt, dev->nodename, 893 "ring-ref", "%u", info->ring_ref); 894 if (err) { 895 message = "writing ring-ref"; 896 goto abort_transaction; 897 } 898 err = xenbus_printf(xbt, dev->nodename, 899 "event-channel", "%u", info->evtchn); 900 if (err) { 901 message = "writing event-channel"; 902 goto abort_transaction; 903 } 904 err = xenbus_printf(xbt, dev->nodename, "protocol", "%s", 905 XEN_IO_PROTO_ABI_NATIVE); 906 if (err) { 907 message = "writing protocol"; 908 goto abort_transaction; 909 } 910 911 err = xenbus_transaction_end(xbt, 0); 912 if (err) { 913 if (err == -EAGAIN) 914 goto again; 915 xenbus_dev_fatal(dev, err, "completing transaction"); 916 goto destroy_blkring; 917 } 918 919 xenbus_switch_state(dev, XenbusStateInitialised); 920 921 return 0; 922 923 abort_transaction: 924 xenbus_transaction_end(xbt, 1); 925 if (message) 926 xenbus_dev_fatal(dev, err, "%s", message); 927 destroy_blkring: 928 blkif_free(info, 0); 929 out: 930 return err; 931 } 932 933 /** 934 * Entry point to this code when a new device is created. Allocate the basic 935 * structures and the ring buffer for communication with the backend, and 936 * inform the backend of the appropriate details for those. Switch to 937 * Initialised state. 938 */ 939 static int blkfront_probe(struct xenbus_device *dev, 940 const struct xenbus_device_id *id) 941 { 942 int err, vdevice, i; 943 struct blkfront_info *info; 944 945 /* FIXME: Use dynamic device id if this is not set. */ 946 err = xenbus_scanf(XBT_NIL, dev->nodename, 947 "virtual-device", "%i", &vdevice); 948 if (err != 1) { 949 /* go looking in the extended area instead */ 950 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext", 951 "%i", &vdevice); 952 if (err != 1) { 953 xenbus_dev_fatal(dev, err, "reading virtual-device"); 954 return err; 955 } 956 } 957 958 if (xen_hvm_domain()) { 959 char *type; 960 int len; 961 /* no unplug has been done: do not hook devices != xen vbds */ 962 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) { 963 int major; 964 965 if (!VDEV_IS_EXTENDED(vdevice)) 966 major = BLKIF_MAJOR(vdevice); 967 else 968 major = XENVBD_MAJOR; 969 970 if (major != XENVBD_MAJOR) { 971 printk(KERN_INFO 972 "%s: HVM does not support vbd %d as xen block device\n", 973 __FUNCTION__, vdevice); 974 return -ENODEV; 975 } 976 } 977 /* do not create a PV cdrom device if we are an HVM guest */ 978 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len); 979 if (IS_ERR(type)) 980 return -ENODEV; 981 if (strncmp(type, "cdrom", 5) == 0) { 982 kfree(type); 983 return -ENODEV; 984 } 985 kfree(type); 986 } 987 info = kzalloc(sizeof(*info), GFP_KERNEL); 988 if (!info) { 989 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure"); 990 return -ENOMEM; 991 } 992 993 mutex_init(&info->mutex); 994 info->xbdev = dev; 995 info->vdevice = vdevice; 996 info->connected = BLKIF_STATE_DISCONNECTED; 997 INIT_WORK(&info->work, blkif_restart_queue); 998 999 for (i = 0; i < BLK_RING_SIZE; i++) 1000 info->shadow[i].req.u.rw.id = i+1; 1001 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1002 1003 /* Front end dir is a number, which is used as the id. */ 1004 info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0); 1005 dev_set_drvdata(&dev->dev, info); 1006 1007 err = talk_to_blkback(dev, info); 1008 if (err) { 1009 kfree(info); 1010 dev_set_drvdata(&dev->dev, NULL); 1011 return err; 1012 } 1013 1014 return 0; 1015 } 1016 1017 1018 static int blkif_recover(struct blkfront_info *info) 1019 { 1020 int i; 1021 struct blkif_request *req; 1022 struct blk_shadow *copy; 1023 int j; 1024 1025 /* Stage 1: Make a safe copy of the shadow state. */ 1026 copy = kmalloc(sizeof(info->shadow), 1027 GFP_NOIO | __GFP_REPEAT | __GFP_HIGH); 1028 if (!copy) 1029 return -ENOMEM; 1030 memcpy(copy, info->shadow, sizeof(info->shadow)); 1031 1032 /* Stage 2: Set up free list. */ 1033 memset(&info->shadow, 0, sizeof(info->shadow)); 1034 for (i = 0; i < BLK_RING_SIZE; i++) 1035 info->shadow[i].req.u.rw.id = i+1; 1036 info->shadow_free = info->ring.req_prod_pvt; 1037 info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff; 1038 1039 /* Stage 3: Find pending requests and requeue them. */ 1040 for (i = 0; i < BLK_RING_SIZE; i++) { 1041 /* Not in use? */ 1042 if (!copy[i].request) 1043 continue; 1044 1045 /* Grab a request slot and copy shadow state into it. */ 1046 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt); 1047 *req = copy[i].req; 1048 1049 /* We get a new request id, and must reset the shadow state. */ 1050 req->u.rw.id = get_id_from_freelist(info); 1051 memcpy(&info->shadow[req->u.rw.id], ©[i], sizeof(copy[i])); 1052 1053 if (req->operation != BLKIF_OP_DISCARD) { 1054 /* Rewrite any grant references invalidated by susp/resume. */ 1055 for (j = 0; j < req->u.rw.nr_segments; j++) 1056 gnttab_grant_foreign_access_ref( 1057 req->u.rw.seg[j].gref, 1058 info->xbdev->otherend_id, 1059 pfn_to_mfn(info->shadow[req->u.rw.id].frame[j]), 1060 rq_data_dir(info->shadow[req->u.rw.id].request)); 1061 } 1062 info->shadow[req->u.rw.id].req = *req; 1063 1064 info->ring.req_prod_pvt++; 1065 } 1066 1067 kfree(copy); 1068 1069 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1070 1071 spin_lock_irq(&blkif_io_lock); 1072 1073 /* Now safe for us to use the shared ring */ 1074 info->connected = BLKIF_STATE_CONNECTED; 1075 1076 /* Send off requeued requests */ 1077 flush_requests(info); 1078 1079 /* Kick any other new requests queued since we resumed */ 1080 kick_pending_request_queues(info); 1081 1082 spin_unlock_irq(&blkif_io_lock); 1083 1084 return 0; 1085 } 1086 1087 /** 1088 * We are reconnecting to the backend, due to a suspend/resume, or a backend 1089 * driver restart. We tear down our blkif structure and recreate it, but 1090 * leave the device-layer structures intact so that this is transparent to the 1091 * rest of the kernel. 1092 */ 1093 static int blkfront_resume(struct xenbus_device *dev) 1094 { 1095 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1096 int err; 1097 1098 dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename); 1099 1100 blkif_free(info, info->connected == BLKIF_STATE_CONNECTED); 1101 1102 err = talk_to_blkback(dev, info); 1103 if (info->connected == BLKIF_STATE_SUSPENDED && !err) 1104 err = blkif_recover(info); 1105 1106 return err; 1107 } 1108 1109 static void 1110 blkfront_closing(struct blkfront_info *info) 1111 { 1112 struct xenbus_device *xbdev = info->xbdev; 1113 struct block_device *bdev = NULL; 1114 1115 mutex_lock(&info->mutex); 1116 1117 if (xbdev->state == XenbusStateClosing) { 1118 mutex_unlock(&info->mutex); 1119 return; 1120 } 1121 1122 if (info->gd) 1123 bdev = bdget_disk(info->gd, 0); 1124 1125 mutex_unlock(&info->mutex); 1126 1127 if (!bdev) { 1128 xenbus_frontend_closed(xbdev); 1129 return; 1130 } 1131 1132 mutex_lock(&bdev->bd_mutex); 1133 1134 if (bdev->bd_openers) { 1135 xenbus_dev_error(xbdev, -EBUSY, 1136 "Device in use; refusing to close"); 1137 xenbus_switch_state(xbdev, XenbusStateClosing); 1138 } else { 1139 xlvbd_release_gendisk(info); 1140 xenbus_frontend_closed(xbdev); 1141 } 1142 1143 mutex_unlock(&bdev->bd_mutex); 1144 bdput(bdev); 1145 } 1146 1147 static void blkfront_setup_discard(struct blkfront_info *info) 1148 { 1149 int err; 1150 char *type; 1151 unsigned int discard_granularity; 1152 unsigned int discard_alignment; 1153 unsigned int discard_secure; 1154 1155 type = xenbus_read(XBT_NIL, info->xbdev->otherend, "type", NULL); 1156 if (IS_ERR(type)) 1157 return; 1158 1159 info->feature_secdiscard = 0; 1160 if (strncmp(type, "phy", 3) == 0) { 1161 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1162 "discard-granularity", "%u", &discard_granularity, 1163 "discard-alignment", "%u", &discard_alignment, 1164 NULL); 1165 if (!err) { 1166 info->feature_discard = 1; 1167 info->discard_granularity = discard_granularity; 1168 info->discard_alignment = discard_alignment; 1169 } 1170 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1171 "discard-secure", "%d", &discard_secure, 1172 NULL); 1173 if (!err) 1174 info->feature_secdiscard = discard_secure; 1175 1176 } else if (strncmp(type, "file", 4) == 0) 1177 info->feature_discard = 1; 1178 1179 kfree(type); 1180 } 1181 1182 /* 1183 * Invoked when the backend is finally 'ready' (and has told produced 1184 * the details about the physical device - #sectors, size, etc). 1185 */ 1186 static void blkfront_connect(struct blkfront_info *info) 1187 { 1188 unsigned long long sectors; 1189 unsigned long sector_size; 1190 unsigned int binfo; 1191 int err; 1192 int barrier, flush, discard; 1193 1194 switch (info->connected) { 1195 case BLKIF_STATE_CONNECTED: 1196 /* 1197 * Potentially, the back-end may be signalling 1198 * a capacity change; update the capacity. 1199 */ 1200 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend, 1201 "sectors", "%Lu", §ors); 1202 if (XENBUS_EXIST_ERR(err)) 1203 return; 1204 printk(KERN_INFO "Setting capacity to %Lu\n", 1205 sectors); 1206 set_capacity(info->gd, sectors); 1207 revalidate_disk(info->gd); 1208 1209 /* fall through */ 1210 case BLKIF_STATE_SUSPENDED: 1211 return; 1212 1213 default: 1214 break; 1215 } 1216 1217 dev_dbg(&info->xbdev->dev, "%s:%s.\n", 1218 __func__, info->xbdev->otherend); 1219 1220 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1221 "sectors", "%llu", §ors, 1222 "info", "%u", &binfo, 1223 "sector-size", "%lu", §or_size, 1224 NULL); 1225 if (err) { 1226 xenbus_dev_fatal(info->xbdev, err, 1227 "reading backend fields at %s", 1228 info->xbdev->otherend); 1229 return; 1230 } 1231 1232 info->feature_flush = 0; 1233 info->flush_op = 0; 1234 1235 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1236 "feature-barrier", "%d", &barrier, 1237 NULL); 1238 1239 /* 1240 * If there's no "feature-barrier" defined, then it means 1241 * we're dealing with a very old backend which writes 1242 * synchronously; nothing to do. 1243 * 1244 * If there are barriers, then we use flush. 1245 */ 1246 if (!err && barrier) { 1247 info->feature_flush = REQ_FLUSH | REQ_FUA; 1248 info->flush_op = BLKIF_OP_WRITE_BARRIER; 1249 } 1250 /* 1251 * And if there is "feature-flush-cache" use that above 1252 * barriers. 1253 */ 1254 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1255 "feature-flush-cache", "%d", &flush, 1256 NULL); 1257 1258 if (!err && flush) { 1259 info->feature_flush = REQ_FLUSH; 1260 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE; 1261 } 1262 1263 err = xenbus_gather(XBT_NIL, info->xbdev->otherend, 1264 "feature-discard", "%d", &discard, 1265 NULL); 1266 1267 if (!err && discard) 1268 blkfront_setup_discard(info); 1269 1270 err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size); 1271 if (err) { 1272 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s", 1273 info->xbdev->otherend); 1274 return; 1275 } 1276 1277 xenbus_switch_state(info->xbdev, XenbusStateConnected); 1278 1279 /* Kick pending requests. */ 1280 spin_lock_irq(&blkif_io_lock); 1281 info->connected = BLKIF_STATE_CONNECTED; 1282 kick_pending_request_queues(info); 1283 spin_unlock_irq(&blkif_io_lock); 1284 1285 add_disk(info->gd); 1286 1287 info->is_ready = 1; 1288 } 1289 1290 /** 1291 * Callback received when the backend's state changes. 1292 */ 1293 static void blkback_changed(struct xenbus_device *dev, 1294 enum xenbus_state backend_state) 1295 { 1296 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1297 1298 dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state); 1299 1300 switch (backend_state) { 1301 case XenbusStateInitialising: 1302 case XenbusStateInitWait: 1303 case XenbusStateInitialised: 1304 case XenbusStateReconfiguring: 1305 case XenbusStateReconfigured: 1306 case XenbusStateUnknown: 1307 case XenbusStateClosed: 1308 break; 1309 1310 case XenbusStateConnected: 1311 blkfront_connect(info); 1312 break; 1313 1314 case XenbusStateClosing: 1315 blkfront_closing(info); 1316 break; 1317 } 1318 } 1319 1320 static int blkfront_remove(struct xenbus_device *xbdev) 1321 { 1322 struct blkfront_info *info = dev_get_drvdata(&xbdev->dev); 1323 struct block_device *bdev = NULL; 1324 struct gendisk *disk; 1325 1326 dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); 1327 1328 blkif_free(info, 0); 1329 1330 mutex_lock(&info->mutex); 1331 1332 disk = info->gd; 1333 if (disk) 1334 bdev = bdget_disk(disk, 0); 1335 1336 info->xbdev = NULL; 1337 mutex_unlock(&info->mutex); 1338 1339 if (!bdev) { 1340 kfree(info); 1341 return 0; 1342 } 1343 1344 /* 1345 * The xbdev was removed before we reached the Closed 1346 * state. See if it's safe to remove the disk. If the bdev 1347 * isn't closed yet, we let release take care of it. 1348 */ 1349 1350 mutex_lock(&bdev->bd_mutex); 1351 info = disk->private_data; 1352 1353 dev_warn(disk_to_dev(disk), 1354 "%s was hot-unplugged, %d stale handles\n", 1355 xbdev->nodename, bdev->bd_openers); 1356 1357 if (info && !bdev->bd_openers) { 1358 xlvbd_release_gendisk(info); 1359 disk->private_data = NULL; 1360 kfree(info); 1361 } 1362 1363 mutex_unlock(&bdev->bd_mutex); 1364 bdput(bdev); 1365 1366 return 0; 1367 } 1368 1369 static int blkfront_is_ready(struct xenbus_device *dev) 1370 { 1371 struct blkfront_info *info = dev_get_drvdata(&dev->dev); 1372 1373 return info->is_ready && info->xbdev; 1374 } 1375 1376 static int blkif_open(struct block_device *bdev, fmode_t mode) 1377 { 1378 struct gendisk *disk = bdev->bd_disk; 1379 struct blkfront_info *info; 1380 int err = 0; 1381 1382 mutex_lock(&blkfront_mutex); 1383 1384 info = disk->private_data; 1385 if (!info) { 1386 /* xbdev gone */ 1387 err = -ERESTARTSYS; 1388 goto out; 1389 } 1390 1391 mutex_lock(&info->mutex); 1392 1393 if (!info->gd) 1394 /* xbdev is closed */ 1395 err = -ERESTARTSYS; 1396 1397 mutex_unlock(&info->mutex); 1398 1399 out: 1400 mutex_unlock(&blkfront_mutex); 1401 return err; 1402 } 1403 1404 static int blkif_release(struct gendisk *disk, fmode_t mode) 1405 { 1406 struct blkfront_info *info = disk->private_data; 1407 struct block_device *bdev; 1408 struct xenbus_device *xbdev; 1409 1410 mutex_lock(&blkfront_mutex); 1411 1412 bdev = bdget_disk(disk, 0); 1413 bdput(bdev); 1414 1415 if (bdev->bd_openers) 1416 goto out; 1417 1418 /* 1419 * Check if we have been instructed to close. We will have 1420 * deferred this request, because the bdev was still open. 1421 */ 1422 1423 mutex_lock(&info->mutex); 1424 xbdev = info->xbdev; 1425 1426 if (xbdev && xbdev->state == XenbusStateClosing) { 1427 /* pending switch to state closed */ 1428 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 1429 xlvbd_release_gendisk(info); 1430 xenbus_frontend_closed(info->xbdev); 1431 } 1432 1433 mutex_unlock(&info->mutex); 1434 1435 if (!xbdev) { 1436 /* sudden device removal */ 1437 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n"); 1438 xlvbd_release_gendisk(info); 1439 disk->private_data = NULL; 1440 kfree(info); 1441 } 1442 1443 out: 1444 mutex_unlock(&blkfront_mutex); 1445 return 0; 1446 } 1447 1448 static const struct block_device_operations xlvbd_block_fops = 1449 { 1450 .owner = THIS_MODULE, 1451 .open = blkif_open, 1452 .release = blkif_release, 1453 .getgeo = blkif_getgeo, 1454 .ioctl = blkif_ioctl, 1455 }; 1456 1457 1458 static const struct xenbus_device_id blkfront_ids[] = { 1459 { "vbd" }, 1460 { "" } 1461 }; 1462 1463 static DEFINE_XENBUS_DRIVER(blkfront, , 1464 .probe = blkfront_probe, 1465 .remove = blkfront_remove, 1466 .resume = blkfront_resume, 1467 .otherend_changed = blkback_changed, 1468 .is_ready = blkfront_is_ready, 1469 ); 1470 1471 static int __init xlblk_init(void) 1472 { 1473 int ret; 1474 1475 if (!xen_domain()) 1476 return -ENODEV; 1477 1478 if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) { 1479 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n", 1480 XENVBD_MAJOR, DEV_NAME); 1481 return -ENODEV; 1482 } 1483 1484 ret = xenbus_register_frontend(&blkfront_driver); 1485 if (ret) { 1486 unregister_blkdev(XENVBD_MAJOR, DEV_NAME); 1487 return ret; 1488 } 1489 1490 return 0; 1491 } 1492 module_init(xlblk_init); 1493 1494 1495 static void __exit xlblk_exit(void) 1496 { 1497 return xenbus_unregister_driver(&blkfront_driver); 1498 } 1499 module_exit(xlblk_exit); 1500 1501 MODULE_DESCRIPTION("Xen virtual block device frontend"); 1502 MODULE_LICENSE("GPL"); 1503 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR); 1504 MODULE_ALIAS("xen:vbd"); 1505 MODULE_ALIAS("xenblk"); 1506