drivers/block/xen-blkfront.c

   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
  44 #include <xen/xenbus.h>
  45 #include <xen/grant_table.h>
  46 #include <xen/events.h>
  47 #include <xen/page.h>
  48
  49 #include <xen/interface/grant_table.h>
  50 #include <xen/interface/io/blkif.h>
  51 #include <xen/interface/io/protocols.h>
  52
  53 #include <asm/xen/hypervisor.h>
  54
  55 enum blkif_state {
  56         BLKIF_STATE_DISCONNECTED,
  57         BLKIF_STATE_CONNECTED,
  58         BLKIF_STATE_SUSPENDED,
  59 };
  60
  61 struct blk_shadow {
  62         struct blkif_request req;
  63         unsigned long request;
  64         unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  65 };
  66
  67 static struct block_device_operations xlvbd_block_fops;
  68
  69 #define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
  70
  71 /*
  72  * We have one of these per vbd, whether ide, scsi or 'other'.  They
  73  * hang in private_data off the gendisk structure. We may end up
  74  * putting all kinds of interesting stuff here :-)
  75  */
  76 struct blkfront_info
  77 {
  78         struct xenbus_device *xbdev;
  79         struct gendisk *gd;
  80         int vdevice;
  81         blkif_vdev_t handle;
  82         enum blkif_state connected;
  83         int ring_ref;
  84         struct blkif_front_ring ring;
  85         unsigned int evtchn, irq;
  86         struct request_queue *rq;
  87         struct work_struct work;
  88         struct gnttab_free_callback callback;
  89         struct blk_shadow shadow[BLK_RING_SIZE];
  90         unsigned long shadow_free;
  91         int feature_barrier;
  92         int is_ready;
  93
  94         /**
  95          * The number of people holding this device open.  We won't allow a
  96          * hot-unplug unless this is 0.
  97          */
  98         int users;
  99 };
 100
 101 static DEFINE_SPINLOCK(blkif_io_lock);
 102
 103 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
 104         (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
 105 #define GRANT_INVALID_REF       0
 106
 107 #define PARTS_PER_DISK          16
 108 #define PARTS_PER_EXT_DISK      256
 109
 110 #define BLKIF_MAJOR(dev) ((dev)>>8)
 111 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 112
 113 #define EXT_SHIFT 28
 114 #define EXTENDED (1<<EXT_SHIFT)
 115 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 116 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 117
 118 #define DEV_NAME        "xvd"   /* name in /dev */
 119
 120 static int get_id_from_freelist(struct blkfront_info *info)
 121 {
 122         unsigned long free = info->shadow_free;
 123         BUG_ON(free > BLK_RING_SIZE);
 124         info->shadow_free = info->shadow[free].req.id;
 125         info->shadow[free].req.id = 0x0fffffee; /* debug */
 126         return free;
 127 }
 128
 129 static void add_id_to_freelist(struct blkfront_info *info,
 130                                unsigned long id)
 131 {
 132         info->shadow[id].req.id  = info->shadow_free;
 133         info->shadow[id].request = 0;
 134         info->shadow_free = id;
 135 }
 136
 137 static void blkif_restart_queue_callback(void *arg)
 138 {
 139         struct blkfront_info *info = (struct blkfront_info *)arg;
 140         schedule_work(&info->work);
 141 }
 142
 143 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 144 {
 145         /* We don't have real geometry info, but let's at least return
 146            values consistent with the size of the device */
 147         sector_t nsect = get_capacity(bd->bd_disk);
 148         sector_t cylinders = nsect;
 149
 150         hg->heads = 0xff;
 151         hg->sectors = 0x3f;
 152         sector_div(cylinders, hg->heads * hg->sectors);
 153         hg->cylinders = cylinders;
 154         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 155                 hg->cylinders = 0xffff;
 156         return 0;
 157 }
 158
 159 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 160                        unsigned command, unsigned long argument)
 161 {
 162         struct blkfront_info *info = bdev->bd_disk->private_data;
 163         int i;
 164
 165         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 166                 command, (long)argument);
 167
 168         switch (command) {
 169         case CDROMMULTISESSION:
 170                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 171                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 172                         if (put_user(0, (char __user *)(argument + i)))
 173                                 return -EFAULT;
 174                 return 0;
 175
 176         case CDROM_GET_CAPABILITY: {
 177                 struct gendisk *gd = info->gd;
 178                 if (gd->flags & GENHD_FL_CD)
 179                         return 0;
 180                 return -EINVAL;
 181         }
 182
 183         default:
 184                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 185                   command);*/
 186                 return -EINVAL; /* same return as native Linux */
 187         }
 188
 189         return 0;
 190 }
 191
 192 /*
 193  * blkif_queue_request
 194  *
 195  * request block io
 196  *
 197  * id: for guest use only.
 198  * operation: BLKIF_OP_{READ,WRITE,PROBE}
 199  * buffer: buffer to read/write into. this should be a
 200  *   virtual address in the guest os.
 201  */
 202 static int blkif_queue_request(struct request *req)
 203 {
 204         struct blkfront_info *info = req->rq_disk->private_data;
 205         unsigned long buffer_mfn;
 206         struct blkif_request *ring_req;
 207         struct req_iterator iter;
 208         struct bio_vec *bvec;
 209         unsigned long id;
 210         unsigned int fsect, lsect;
 211         int ref;
 212         grant_ref_t gref_head;
 213
 214         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
 215                 return 1;
 216
 217         if (gnttab_alloc_grant_references(
 218                 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
 219                 gnttab_request_free_callback(
 220                         &info->callback,
 221                         blkif_restart_queue_callback,
 222                         info,
 223                         BLKIF_MAX_SEGMENTS_PER_REQUEST);
 224                 return 1;
 225         }
 226
 227         /* Fill out a communications ring structure. */
 228         ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
 229         id = get_id_from_freelist(info);
 230         info->shadow[id].request = (unsigned long)req;
 231
 232         ring_req->id = id;
 233         ring_req->sector_number = (blkif_sector_t)req->sector;
 234         ring_req->handle = info->handle;
 235
 236         ring_req->operation = rq_data_dir(req) ?
 237                 BLKIF_OP_WRITE : BLKIF_OP_READ;
 238         if (blk_barrier_rq(req))
 239                 ring_req->operation = BLKIF_OP_WRITE_BARRIER;
 240
 241         ring_req->nr_segments = 0;
 242         rq_for_each_segment(bvec, req, iter) {
 243                 BUG_ON(ring_req->nr_segments == BLKIF_MAX_SEGMENTS_PER_REQUEST);
 244                 buffer_mfn = pfn_to_mfn(page_to_pfn(bvec->bv_page));
 245                 fsect = bvec->bv_offset >> 9;
 246                 lsect = fsect + (bvec->bv_len >> 9) - 1;
 247                 /* install a grant reference. */
 248                 ref = gnttab_claim_grant_reference(&gref_head);
 249                 BUG_ON(ref == -ENOSPC);
 250
 251                 gnttab_grant_foreign_access_ref(
 252                                 ref,
 253                                 info->xbdev->otherend_id,
 254                                 buffer_mfn,
 255                                 rq_data_dir(req) );
 256
 257                 info->shadow[id].frame[ring_req->nr_segments] =
 258                                 mfn_to_pfn(buffer_mfn);
 259
 260                 ring_req->seg[ring_req->nr_segments] =
 261                                 (struct blkif_request_segment) {
 262                                         .gref       = ref,
 263                                         .first_sect = fsect,
 264                                         .last_sect  = lsect };
 265
 266                 ring_req->nr_segments++;
 267         }
 268
 269         info->ring.req_prod_pvt++;
 270
 271         /* Keep a private copy so we can reissue requests when recovering. */
 272         info->shadow[id].req = *ring_req;
 273
 274         gnttab_free_grant_references(gref_head);
 275
 276         return 0;
 277 }
 278
 279
 280 static inline void flush_requests(struct blkfront_info *info)
 281 {
 282         int notify;
 283
 284         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
 285
 286         if (notify)
 287                 notify_remote_via_irq(info->irq);
 288 }
 289
 290 /*
 291  * do_blkif_request
 292  *  read a block; request is in a request queue
 293  */
 294 static void do_blkif_request(struct request_queue *rq)
 295 {
 296         struct blkfront_info *info = NULL;
 297         struct request *req;
 298         int queued;
 299
 300         pr_debug("Entered do_blkif_request\n");
 301
 302         queued = 0;
 303
 304         while ((req = elv_next_request(rq)) != NULL) {
 305                 info = req->rq_disk->private_data;
 306                 if (!blk_fs_request(req)) {
 307                         end_request(req, 0);
 308                         continue;
 309                 }
 310
 311                 if (RING_FULL(&info->ring))
 312                         goto wait;
 313
 314                 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
 315                          "(%u/%li) buffer:%p [%s]\n",
 316                          req, req->cmd, (unsigned long)req->sector,
 317                          req->current_nr_sectors,
 318                          req->nr_sectors, req->buffer,
 319                          rq_data_dir(req) ? "write" : "read");
 320
 321
 322                 blkdev_dequeue_request(req);
 323                 if (blkif_queue_request(req)) {
 324                         blk_requeue_request(rq, req);
 325 wait:
 326                         /* Avoid pointless unplugs. */
 327                         blk_stop_queue(rq);
 328                         break;
 329                 }
 330
 331                 queued++;
 332         }
 333
 334         if (queued != 0)
 335                 flush_requests(info);
 336 }
 337
 338 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
 339 {
 340         struct request_queue *rq;
 341
 342         rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
 343         if (rq == NULL)
 344                 return -1;
 345
 346         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
 347
 348         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 349         blk_queue_hardsect_size(rq, sector_size);
 350         blk_queue_max_sectors(rq, 512);
 351
 352         /* Each segment in a request is up to an aligned page in size. */
 353         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 354         blk_queue_max_segment_size(rq, PAGE_SIZE);
 355
 356         /* Ensure a merged request will fit in a single I/O ring slot. */
 357         blk_queue_max_phys_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 358         blk_queue_max_hw_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 359
 360         /* Make sure buffer addresses are sector-aligned. */
 361         blk_queue_dma_alignment(rq, 511);
 362
 363         /* Make sure we don't use bounce buffers. */
 364         blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
 365
 366         gd->queue = rq;
 367
 368         return 0;
 369 }
 370
 371
 372 static int xlvbd_barrier(struct blkfront_info *info)
 373 {
 374         int err;
 375
 376         err = blk_queue_ordered(info->rq,
 377                                 info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE,
 378                                 NULL);
 379
 380         if (err)
 381                 return err;
 382
 383         printk(KERN_INFO "blkfront: %s: barriers %s\n",
 384                info->gd->disk_name,
 385                info->feature_barrier ? "enabled" : "disabled");
 386         return 0;
 387 }
 388
 389
 390 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 391                                struct blkfront_info *info,
 392                                u16 vdisk_info, u16 sector_size)
 393 {
 394         struct gendisk *gd;
 395         int nr_minors = 1;
 396         int err = -ENODEV;
 397         unsigned int offset;
 398         int minor;
 399         int nr_parts;
 400
 401         BUG_ON(info->gd != NULL);
 402         BUG_ON(info->rq != NULL);
 403
 404         if ((info->vdevice>>EXT_SHIFT) > 1) {
 405                 /* this is above the extended range; something is wrong */
 406                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
 407                 return -ENODEV;
 408         }
 409
 410         if (!VDEV_IS_EXTENDED(info->vdevice)) {
 411                 minor = BLKIF_MINOR(info->vdevice);
 412                 nr_parts = PARTS_PER_DISK;
 413         } else {
 414                 minor = BLKIF_MINOR_EXT(info->vdevice);
 415                 nr_parts = PARTS_PER_EXT_DISK;
 416         }
 417
 418         if ((minor % nr_parts) == 0)
 419                 nr_minors = nr_parts;
 420
 421         gd = alloc_disk(nr_minors);
 422         if (gd == NULL)
 423                 goto out;
 424
 425         offset = minor / nr_parts;
 426
 427         if (nr_minors > 1) {
 428                 if (offset < 26)
 429                         sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
 430                 else
 431                         sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
 432                                 'a' + ((offset / 26)-1), 'a' + (offset % 26));
 433         } else {
 434                 if (offset < 26)
 435                         sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
 436                                 'a' + offset,
 437                                 minor & (nr_parts - 1));
 438                 else
 439                         sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
 440                                 'a' + ((offset / 26) - 1),
 441                                 'a' + (offset % 26),
 442                                 minor & (nr_parts - 1));
 443         }
 444
 445         gd->major = XENVBD_MAJOR;
 446         gd->first_minor = minor;
 447         gd->fops = &xlvbd_block_fops;
 448         gd->private_data = info;
 449         gd->driverfs_dev = &(info->xbdev->dev);
 450         set_capacity(gd, capacity);
 451
 452         if (xlvbd_init_blk_queue(gd, sector_size)) {
 453                 del_gendisk(gd);
 454                 goto out;
 455         }
 456
 457         info->rq = gd->queue;
 458         info->gd = gd;
 459
 460         if (info->feature_barrier)
 461                 xlvbd_barrier(info);
 462
 463         if (vdisk_info & VDISK_READONLY)
 464                 set_disk_ro(gd, 1);
 465
 466         if (vdisk_info & VDISK_REMOVABLE)
 467                 gd->flags |= GENHD_FL_REMOVABLE;
 468
 469         if (vdisk_info & VDISK_CDROM)
 470                 gd->flags |= GENHD_FL_CD;
 471
 472         return 0;
 473
 474  out:
 475         return err;
 476 }
 477
 478 static void kick_pending_request_queues(struct blkfront_info *info)
 479 {
 480         if (!RING_FULL(&info->ring)) {
 481                 /* Re-enable calldowns. */
 482                 blk_start_queue(info->rq);
 483                 /* Kick things off immediately. */
 484                 do_blkif_request(info->rq);
 485         }
 486 }
 487
 488 static void blkif_restart_queue(struct work_struct *work)
 489 {
 490         struct blkfront_info *info = container_of(work, struct blkfront_info, work);
 491
 492         spin_lock_irq(&blkif_io_lock);
 493         if (info->connected == BLKIF_STATE_CONNECTED)
 494                 kick_pending_request_queues(info);
 495         spin_unlock_irq(&blkif_io_lock);
 496 }
 497
 498 static void blkif_free(struct blkfront_info *info, int suspend)
 499 {
 500         /* Prevent new requests being issued until we fix things up. */
 501         spin_lock_irq(&blkif_io_lock);
 502         info->connected = suspend ?
 503                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
 504         /* No more blkif_request(). */
 505         if (info->rq)
 506                 blk_stop_queue(info->rq);
 507         /* No more gnttab callback work. */
 508         gnttab_cancel_free_callback(&info->callback);
 509         spin_unlock_irq(&blkif_io_lock);
 510
 511         /* Flush gnttab callback work. Must be done with no locks held. */
 512         flush_scheduled_work();
 513
 514         /* Free resources associated with old device channel. */
 515         if (info->ring_ref != GRANT_INVALID_REF) {
 516                 gnttab_end_foreign_access(info->ring_ref, 0,
 517                                           (unsigned long)info->ring.sring);
 518                 info->ring_ref = GRANT_INVALID_REF;
 519                 info->ring.sring = NULL;
 520         }
 521         if (info->irq)
 522                 unbind_from_irqhandler(info->irq, info);
 523         info->evtchn = info->irq = 0;
 524
 525 }
 526
 527 static void blkif_completion(struct blk_shadow *s)
 528 {
 529         int i;
 530         for (i = 0; i < s->req.nr_segments; i++)
 531                 gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL);
 532 }
 533
 534 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 535 {
 536         struct request *req;
 537         struct blkif_response *bret;
 538         RING_IDX i, rp;
 539         unsigned long flags;
 540         struct blkfront_info *info = (struct blkfront_info *)dev_id;
 541         int error;
 542
 543         spin_lock_irqsave(&blkif_io_lock, flags);
 544
 545         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
 546                 spin_unlock_irqrestore(&blkif_io_lock, flags);
 547                 return IRQ_HANDLED;
 548         }
 549
 550  again:
 551         rp = info->ring.sring->rsp_prod;
 552         rmb(); /* Ensure we see queued responses up to 'rp'. */
 553
 554         for (i = info->ring.rsp_cons; i != rp; i++) {
 555                 unsigned long id;
 556                 int ret;
 557
 558                 bret = RING_GET_RESPONSE(&info->ring, i);
 559                 id   = bret->id;
 560                 req  = (struct request *)info->shadow[id].request;
 561
 562                 blkif_completion(&info->shadow[id]);
 563
 564                 add_id_to_freelist(info, id);
 565
 566                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
 567                 switch (bret->operation) {
 568                 case BLKIF_OP_WRITE_BARRIER:
 569                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
 570                                 printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
 571                                        info->gd->disk_name);
 572                                 error = -EOPNOTSUPP;
 573                                 info->feature_barrier = 0;
 574                                 xlvbd_barrier(info);
 575                         }
 576                         /* fall through */
 577                 case BLKIF_OP_READ:
 578                 case BLKIF_OP_WRITE:
 579                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
 580                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
 581                                         "request: %x\n", bret->status);
 582
 583                         ret = __blk_end_request(req, error, blk_rq_bytes(req));
 584                         BUG_ON(ret);
 585                         break;
 586                 default:
 587                         BUG();
 588                 }
 589         }
 590
 591         info->ring.rsp_cons = i;
 592
 593         if (i != info->ring.req_prod_pvt) {
 594                 int more_to_do;
 595                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
 596                 if (more_to_do)
 597                         goto again;
 598         } else
 599                 info->ring.sring->rsp_event = i + 1;
 600
 601         kick_pending_request_queues(info);
 602
 603         spin_unlock_irqrestore(&blkif_io_lock, flags);
 604
 605         return IRQ_HANDLED;
 606 }
 607
 608
 609 static int setup_blkring(struct xenbus_device *dev,
 610                          struct blkfront_info *info)
 611 {
 612         struct blkif_sring *sring;
 613         int err;
 614
 615         info->ring_ref = GRANT_INVALID_REF;
 616
 617         sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
 618         if (!sring) {
 619                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
 620                 return -ENOMEM;
 621         }
 622         SHARED_RING_INIT(sring);
 623         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 624
 625         err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
 626         if (err < 0) {
 627                 free_page((unsigned long)sring);
 628                 info->ring.sring = NULL;
 629                 goto fail;
 630         }
 631         info->ring_ref = err;
 632
 633         err = xenbus_alloc_evtchn(dev, &info->evtchn);
 634         if (err)
 635                 goto fail;
 636
 637         err = bind_evtchn_to_irqhandler(info->evtchn,
 638                                         blkif_interrupt,
 639                                         IRQF_SAMPLE_RANDOM, "blkif", info);
 640         if (err <= 0) {
 641                 xenbus_dev_fatal(dev, err,
 642                                  "bind_evtchn_to_irqhandler failed");
 643                 goto fail;
 644         }
 645         info->irq = err;
 646
 647         return 0;
 648 fail:
 649         blkif_free(info, 0);
 650         return err;
 651 }
 652
 653
 654 /* Common code used when first setting up, and when resuming. */
 655 static int talk_to_backend(struct xenbus_device *dev,
 656                            struct blkfront_info *info)
 657 {
 658         const char *message = NULL;
 659         struct xenbus_transaction xbt;
 660         int err;
 661
 662         /* Create shared ring, alloc event channel. */
 663         err = setup_blkring(dev, info);
 664         if (err)
 665                 goto out;
 666
 667 again:
 668         err = xenbus_transaction_start(&xbt);
 669         if (err) {
 670                 xenbus_dev_fatal(dev, err, "starting transaction");
 671                 goto destroy_blkring;
 672         }
 673
 674         err = xenbus_printf(xbt, dev->nodename,
 675                             "ring-ref", "%u", info->ring_ref);
 676         if (err) {
 677                 message = "writing ring-ref";
 678                 goto abort_transaction;
 679         }
 680         err = xenbus_printf(xbt, dev->nodename,
 681                             "event-channel", "%u", info->evtchn);
 682         if (err) {
 683                 message = "writing event-channel";
 684                 goto abort_transaction;
 685         }
 686         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
 687                             XEN_IO_PROTO_ABI_NATIVE);
 688         if (err) {
 689                 message = "writing protocol";
 690                 goto abort_transaction;
 691         }
 692
 693         err = xenbus_transaction_end(xbt, 0);
 694         if (err) {
 695                 if (err == -EAGAIN)
 696                         goto again;
 697                 xenbus_dev_fatal(dev, err, "completing transaction");
 698                 goto destroy_blkring;
 699         }
 700
 701         xenbus_switch_state(dev, XenbusStateInitialised);
 702
 703         return 0;
 704
 705  abort_transaction:
 706         xenbus_transaction_end(xbt, 1);
 707         if (message)
 708                 xenbus_dev_fatal(dev, err, "%s", message);
 709  destroy_blkring:
 710         blkif_free(info, 0);
 711  out:
 712         return err;
 713 }
 714
 715
 716 /**
 717  * Entry point to this code when a new device is created.  Allocate the basic
 718  * structures and the ring buffer for communication with the backend, and
 719  * inform the backend of the appropriate details for those.  Switch to
 720  * Initialised state.
 721  */
 722 static int blkfront_probe(struct xenbus_device *dev,
 723                           const struct xenbus_device_id *id)
 724 {
 725         int err, vdevice, i;
 726         struct blkfront_info *info;
 727
 728         /* FIXME: Use dynamic device id if this is not set. */
 729         err = xenbus_scanf(XBT_NIL, dev->nodename,
 730                            "virtual-device", "%i", &vdevice);
 731         if (err != 1) {
 732                 /* go looking in the extended area instead */
 733                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
 734                                    "%i", &vdevice);
 735                 if (err != 1) {
 736                         xenbus_dev_fatal(dev, err, "reading virtual-device");
 737                         return err;
 738                 }
 739         }
 740
 741         info = kzalloc(sizeof(*info), GFP_KERNEL);
 742         if (!info) {
 743                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
 744                 return -ENOMEM;
 745         }
 746
 747         info->xbdev = dev;
 748         info->vdevice = vdevice;
 749         info->connected = BLKIF_STATE_DISCONNECTED;
 750         INIT_WORK(&info->work, blkif_restart_queue);
 751
 752         for (i = 0; i < BLK_RING_SIZE; i++)
 753                 info->shadow[i].req.id = i+1;
 754         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
 755
 756         /* Front end dir is a number, which is used as the id. */
 757         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
 758         dev->dev.driver_data = info;
 759
 760         err = talk_to_backend(dev, info);
 761         if (err) {
 762                 kfree(info);
 763                 dev->dev.driver_data = NULL;
 764                 return err;
 765         }
 766
 767         return 0;
 768 }
 769
 770
 771 static int blkif_recover(struct blkfront_info *info)
 772 {
 773         int i;
 774         struct blkif_request *req;
 775         struct blk_shadow *copy;
 776         int j;
 777
 778         /* Stage 1: Make a safe copy of the shadow state. */
 779         copy = kmalloc(sizeof(info->shadow),
 780                        GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
 781         if (!copy)
 782                 return -ENOMEM;
 783         memcpy(copy, info->shadow, sizeof(info->shadow));
 784
 785         /* Stage 2: Set up free list. */
 786         memset(&info->shadow, 0, sizeof(info->shadow));
 787         for (i = 0; i < BLK_RING_SIZE; i++)
 788                 info->shadow[i].req.id = i+1;
 789         info->shadow_free = info->ring.req_prod_pvt;
 790         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
 791
 792         /* Stage 3: Find pending requests and requeue them. */
 793         for (i = 0; i < BLK_RING_SIZE; i++) {
 794                 /* Not in use? */
 795                 if (copy[i].request == 0)
 796                         continue;
 797
 798                 /* Grab a request slot and copy shadow state into it. */
 799                 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
 800                 *req = copy[i].req;
 801
 802                 /* We get a new request id, and must reset the shadow state. */
 803                 req->id = get_id_from_freelist(info);
 804                 memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
 805
 806                 /* Rewrite any grant references invalidated by susp/resume. */
 807                 for (j = 0; j < req->nr_segments; j++)
 808                         gnttab_grant_foreign_access_ref(
 809                                 req->seg[j].gref,
 810                                 info->xbdev->otherend_id,
 811                                 pfn_to_mfn(info->shadow[req->id].frame[j]),
 812                                 rq_data_dir(
 813                                         (struct request *)
 814                                         info->shadow[req->id].request));
 815                 info->shadow[req->id].req = *req;
 816
 817                 info->ring.req_prod_pvt++;
 818         }
 819
 820         kfree(copy);
 821
 822         xenbus_switch_state(info->xbdev, XenbusStateConnected);
 823
 824         spin_lock_irq(&blkif_io_lock);
 825
 826         /* Now safe for us to use the shared ring */
 827         info->connected = BLKIF_STATE_CONNECTED;
 828
 829         /* Send off requeued requests */
 830         flush_requests(info);
 831
 832         /* Kick any other new requests queued since we resumed */
 833         kick_pending_request_queues(info);
 834
 835         spin_unlock_irq(&blkif_io_lock);
 836
 837         return 0;
 838 }
 839
 840 /**
 841  * We are reconnecting to the backend, due to a suspend/resume, or a backend
 842  * driver restart.  We tear down our blkif structure and recreate it, but
 843  * leave the device-layer structures intact so that this is transparent to the
 844  * rest of the kernel.
 845  */
 846 static int blkfront_resume(struct xenbus_device *dev)
 847 {
 848         struct blkfront_info *info = dev->dev.driver_data;
 849         int err;
 850
 851         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
 852
 853         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
 854
 855         err = talk_to_backend(dev, info);
 856         if (info->connected == BLKIF_STATE_SUSPENDED && !err)
 857                 err = blkif_recover(info);
 858
 859         return err;
 860 }
 861
 862
 863 /*
 864  * Invoked when the backend is finally 'ready' (and has told produced
 865  * the details about the physical device - #sectors, size, etc).
 866  */
 867 static void blkfront_connect(struct blkfront_info *info)
 868 {
 869         unsigned long long sectors;
 870         unsigned long sector_size;
 871         unsigned int binfo;
 872         int err;
 873
 874         if ((info->connected == BLKIF_STATE_CONNECTED) ||
 875             (info->connected == BLKIF_STATE_SUSPENDED) )
 876                 return;
 877
 878         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
 879                 __func__, info->xbdev->otherend);
 880
 881         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
 882                             "sectors", "%llu", &sectors,
 883                             "info", "%u", &binfo,
 884                             "sector-size", "%lu", &sector_size,
 885                             NULL);
 886         if (err) {
 887                 xenbus_dev_fatal(info->xbdev, err,
 888                                  "reading backend fields at %s",
 889                                  info->xbdev->otherend);
 890                 return;
 891         }
 892
 893         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
 894                             "feature-barrier", "%lu", &info->feature_barrier,
 895                             NULL);
 896         if (err)
 897                 info->feature_barrier = 0;
 898
 899         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
 900         if (err) {
 901                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
 902                                  info->xbdev->otherend);
 903                 return;
 904         }
 905
 906         xenbus_switch_state(info->xbdev, XenbusStateConnected);
 907
 908         /* Kick pending requests. */
 909         spin_lock_irq(&blkif_io_lock);
 910         info->connected = BLKIF_STATE_CONNECTED;
 911         kick_pending_request_queues(info);
 912         spin_unlock_irq(&blkif_io_lock);
 913
 914         add_disk(info->gd);
 915
 916         info->is_ready = 1;
 917 }
 918
 919 /**
 920  * Handle the change of state of the backend to Closing.  We must delete our
 921  * device-layer structures now, to ensure that writes are flushed through to
 922  * the backend.  Once is this done, we can switch to Closed in
 923  * acknowledgement.
 924  */
 925 static void blkfront_closing(struct xenbus_device *dev)
 926 {
 927         struct blkfront_info *info = dev->dev.driver_data;
 928         unsigned long flags;
 929
 930         dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename);
 931
 932         if (info->rq == NULL)
 933                 goto out;
 934
 935         spin_lock_irqsave(&blkif_io_lock, flags);
 936
 937         del_gendisk(info->gd);
 938
 939         /* No more blkif_request(). */
 940         blk_stop_queue(info->rq);
 941
 942         /* No more gnttab callback work. */
 943         gnttab_cancel_free_callback(&info->callback);
 944         spin_unlock_irqrestore(&blkif_io_lock, flags);
 945
 946         /* Flush gnttab callback work. Must be done with no locks held. */
 947         flush_scheduled_work();
 948
 949         blk_cleanup_queue(info->rq);
 950         info->rq = NULL;
 951
 952  out:
 953         xenbus_frontend_closed(dev);
 954 }
 955
 956 /**
 957  * Callback received when the backend's state changes.
 958  */
 959 static void backend_changed(struct xenbus_device *dev,
 960                             enum xenbus_state backend_state)
 961 {
 962         struct blkfront_info *info = dev->dev.driver_data;
 963         struct block_device *bd;
 964
 965         dev_dbg(&dev->dev, "blkfront:backend_changed.\n");
 966
 967         switch (backend_state) {
 968         case XenbusStateInitialising:
 969         case XenbusStateInitWait:
 970         case XenbusStateInitialised:
 971         case XenbusStateUnknown:
 972         case XenbusStateClosed:
 973                 break;
 974
 975         case XenbusStateConnected:
 976                 blkfront_connect(info);
 977                 break;
 978
 979         case XenbusStateClosing:
 980                 bd = bdget_disk(info->gd, 0);
 981                 if (bd == NULL)
 982                         xenbus_dev_fatal(dev, -ENODEV, "bdget failed");
 983
 984                 mutex_lock(&bd->bd_mutex);
 985                 if (info->users > 0)
 986                         xenbus_dev_error(dev, -EBUSY,
 987                                          "Device in use; refusing to close");
 988                 else
 989                         blkfront_closing(dev);
 990                 mutex_unlock(&bd->bd_mutex);
 991                 bdput(bd);
 992                 break;
 993         }
 994 }
 995
 996 static int blkfront_remove(struct xenbus_device *dev)
 997 {
 998         struct blkfront_info *info = dev->dev.driver_data;
 999
1000         dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename);
1001
1002         blkif_free(info, 0);
1003
1004         kfree(info);
1005
1006         return 0;
1007 }
1008
1009 static int blkfront_is_ready(struct xenbus_device *dev)
1010 {
1011         struct blkfront_info *info = dev->dev.driver_data;
1012
1013         return info->is_ready;
1014 }
1015
1016 static int blkif_open(struct block_device *bdev, fmode_t mode)
1017 {
1018         struct blkfront_info *info = bdev->bd_disk->private_data;
1019         info->users++;
1020         return 0;
1021 }
1022
1023 static int blkif_release(struct gendisk *disk, fmode_t mode)
1024 {
1025         struct blkfront_info *info = disk->private_data;
1026         info->users--;
1027         if (info->users == 0) {
1028                 /* Check whether we have been instructed to close.  We will
1029                    have ignored this request initially, as the device was
1030                    still mounted. */
1031                 struct xenbus_device *dev = info->xbdev;
1032                 enum xenbus_state state = xenbus_read_driver_state(dev->otherend);
1033
1034                 if (state == XenbusStateClosing && info->is_ready)
1035                         blkfront_closing(dev);
1036         }
1037         return 0;
1038 }
1039
1040 static struct block_device_operations xlvbd_block_fops =
1041 {
1042         .owner = THIS_MODULE,
1043         .open = blkif_open,
1044         .release = blkif_release,
1045         .getgeo = blkif_getgeo,
1046         .locked_ioctl = blkif_ioctl,
1047 };
1048
1049
1050 static struct xenbus_device_id blkfront_ids[] = {
1051         { "vbd" },
1052         { "" }
1053 };
1054
1055 static struct xenbus_driver blkfront = {
1056         .name = "vbd",
1057         .owner = THIS_MODULE,
1058         .ids = blkfront_ids,
1059         .probe = blkfront_probe,
1060         .remove = blkfront_remove,
1061         .resume = blkfront_resume,
1062         .otherend_changed = backend_changed,
1063         .is_ready = blkfront_is_ready,
1064 };
1065
1066 static int __init xlblk_init(void)
1067 {
1068         if (!xen_domain())
1069                 return -ENODEV;
1070
1071         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1072                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1073                        XENVBD_MAJOR, DEV_NAME);
1074                 return -ENODEV;
1075         }
1076
1077         return xenbus_register_frontend(&blkfront);
1078 }
1079 module_init(xlblk_init);
1080
1081
1082 static void __exit xlblk_exit(void)
1083 {
1084         return xenbus_unregister_driver(&blkfront);
1085 }
1086 module_exit(xlblk_exit);
1087
1088 MODULE_DESCRIPTION("Xen virtual block device frontend");
1089 MODULE_LICENSE("GPL");
1090 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1091 MODULE_ALIAS("xen:vbd");
1092 MODULE_ALIAS("xenblk");