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 #include <linux/scatterlist.h>
  44
  45 #include <xen/xenbus.h>
  46 #include <xen/grant_table.h>
  47 #include <xen/events.h>
  48 #include <xen/page.h>
  49
  50 #include <xen/interface/grant_table.h>
  51 #include <xen/interface/io/blkif.h>
  52 #include <xen/interface/io/protocols.h>
  53
  54 #include <asm/xen/hypervisor.h>
  55
  56 enum blkif_state {
  57         BLKIF_STATE_DISCONNECTED,
  58         BLKIF_STATE_CONNECTED,
  59         BLKIF_STATE_SUSPENDED,
  60 };
  61
  62 struct blk_shadow {
  63         struct blkif_request req;
  64         unsigned long request;
  65         unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  66 };
  67
  68 static struct block_device_operations xlvbd_block_fops;
  69
  70 #define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
  71
  72 /*
  73  * We have one of these per vbd, whether ide, scsi or 'other'.  They
  74  * hang in private_data off the gendisk structure. We may end up
  75  * putting all kinds of interesting stuff here :-)
  76  */
  77 struct blkfront_info
  78 {
  79         struct xenbus_device *xbdev;
  80         struct gendisk *gd;
  81         int vdevice;
  82         blkif_vdev_t handle;
  83         enum blkif_state connected;
  84         int ring_ref;
  85         struct blkif_front_ring ring;
  86         struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  87         unsigned int evtchn, irq;
  88         struct request_queue *rq;
  89         struct work_struct work;
  90         struct gnttab_free_callback callback;
  91         struct blk_shadow shadow[BLK_RING_SIZE];
  92         unsigned long shadow_free;
  93         int feature_barrier;
  94         int is_ready;
  95
  96         /**
  97          * The number of people holding this device open.  We won't allow a
  98          * hot-unplug unless this is 0.
  99          */
 100         int users;
 101 };
 102
 103 static DEFINE_SPINLOCK(blkif_io_lock);
 104
 105 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
 106         (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
 107 #define GRANT_INVALID_REF       0
 108
 109 #define PARTS_PER_DISK          16
 110 #define PARTS_PER_EXT_DISK      256
 111
 112 #define BLKIF_MAJOR(dev) ((dev)>>8)
 113 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 114
 115 #define EXT_SHIFT 28
 116 #define EXTENDED (1<<EXT_SHIFT)
 117 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 118 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 119
 120 #define DEV_NAME        "xvd"   /* name in /dev */
 121
 122 static int get_id_from_freelist(struct blkfront_info *info)
 123 {
 124         unsigned long free = info->shadow_free;
 125         BUG_ON(free >= BLK_RING_SIZE);
 126         info->shadow_free = info->shadow[free].req.id;
 127         info->shadow[free].req.id = 0x0fffffee; /* debug */
 128         return free;
 129 }
 130
 131 static void add_id_to_freelist(struct blkfront_info *info,
 132                                unsigned long id)
 133 {
 134         info->shadow[id].req.id  = info->shadow_free;
 135         info->shadow[id].request = 0;
 136         info->shadow_free = id;
 137 }
 138
 139 static void blkif_restart_queue_callback(void *arg)
 140 {
 141         struct blkfront_info *info = (struct blkfront_info *)arg;
 142         schedule_work(&info->work);
 143 }
 144
 145 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 146 {
 147         /* We don't have real geometry info, but let's at least return
 148            values consistent with the size of the device */
 149         sector_t nsect = get_capacity(bd->bd_disk);
 150         sector_t cylinders = nsect;
 151
 152         hg->heads = 0xff;
 153         hg->sectors = 0x3f;
 154         sector_div(cylinders, hg->heads * hg->sectors);
 155         hg->cylinders = cylinders;
 156         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 157                 hg->cylinders = 0xffff;
 158         return 0;
 159 }
 160
 161 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 162                        unsigned command, unsigned long argument)
 163 {
 164         struct blkfront_info *info = bdev->bd_disk->private_data;
 165         int i;
 166
 167         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 168                 command, (long)argument);
 169
 170         switch (command) {
 171         case CDROMMULTISESSION:
 172                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 173                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 174                         if (put_user(0, (char __user *)(argument + i)))
 175                                 return -EFAULT;
 176                 return 0;
 177
 178         case CDROM_GET_CAPABILITY: {
 179                 struct gendisk *gd = info->gd;
 180                 if (gd->flags & GENHD_FL_CD)
 181                         return 0;
 182                 return -EINVAL;
 183         }
 184
 185         default:
 186                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 187                   command);*/
 188                 return -EINVAL; /* same return as native Linux */
 189         }
 190
 191         return 0;
 192 }
 193
 194 /*
 195  * blkif_queue_request
 196  *
 197  * request block io
 198  *
 199  * id: for guest use only.
 200  * operation: BLKIF_OP_{READ,WRITE,PROBE}
 201  * buffer: buffer to read/write into. this should be a
 202  *   virtual address in the guest os.
 203  */
 204 static int blkif_queue_request(struct request *req)
 205 {
 206         struct blkfront_info *info = req->rq_disk->private_data;
 207         unsigned long buffer_mfn;
 208         struct blkif_request *ring_req;
 209         unsigned long id;
 210         unsigned int fsect, lsect;
 211         int i, ref;
 212         grant_ref_t gref_head;
 213         struct scatterlist *sg;
 214
 215         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
 216                 return 1;
 217
 218         if (gnttab_alloc_grant_references(
 219                 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
 220                 gnttab_request_free_callback(
 221                         &info->callback,
 222                         blkif_restart_queue_callback,
 223                         info,
 224                         BLKIF_MAX_SEGMENTS_PER_REQUEST);
 225                 return 1;
 226         }
 227
 228         /* Fill out a communications ring structure. */
 229         ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
 230         id = get_id_from_freelist(info);
 231         info->shadow[id].request = (unsigned long)req;
 232
 233         ring_req->id = id;
 234         ring_req->sector_number = (blkif_sector_t)blk_rq_pos(req);
 235         ring_req->handle = info->handle;
 236
 237         ring_req->operation = rq_data_dir(req) ?
 238                 BLKIF_OP_WRITE : BLKIF_OP_READ;
 239         if (blk_barrier_rq(req))
 240                 ring_req->operation = BLKIF_OP_WRITE_BARRIER;
 241
 242         ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
 243         BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
 244
 245         for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
 246                 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
 247                 fsect = sg->offset >> 9;
 248                 lsect = fsect + (sg->length >> 9) - 1;
 249                 /* install a grant reference. */
 250                 ref = gnttab_claim_grant_reference(&gref_head);
 251                 BUG_ON(ref == -ENOSPC);
 252
 253                 gnttab_grant_foreign_access_ref(
 254                                 ref,
 255                                 info->xbdev->otherend_id,
 256                                 buffer_mfn,
 257                                 rq_data_dir(req) );
 258
 259                 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
 260                 ring_req->seg[i] =
 261                                 (struct blkif_request_segment) {
 262                                         .gref       = ref,
 263                                         .first_sect = fsect,
 264                                         .last_sect  = lsect };
 265         }
 266
 267         info->ring.req_prod_pvt++;
 268
 269         /* Keep a private copy so we can reissue requests when recovering. */
 270         info->shadow[id].req = *ring_req;
 271
 272         gnttab_free_grant_references(gref_head);
 273
 274         return 0;
 275 }
 276
 277
 278 static inline void flush_requests(struct blkfront_info *info)
 279 {
 280         int notify;
 281
 282         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
 283
 284         if (notify)
 285                 notify_remote_via_irq(info->irq);
 286 }
 287
 288 /*
 289  * do_blkif_request
 290  *  read a block; request is in a request queue
 291  */
 292 static void do_blkif_request(struct request_queue *rq)
 293 {
 294         struct blkfront_info *info = NULL;
 295         struct request *req;
 296         int queued;
 297
 298         pr_debug("Entered do_blkif_request\n");
 299
 300         queued = 0;
 301
 302         while ((req = blk_peek_request(rq)) != NULL) {
 303                 info = req->rq_disk->private_data;
 304
 305                 if (RING_FULL(&info->ring))
 306                         goto wait;
 307
 308                 blk_start_request(req);
 309
 310                 if (!blk_fs_request(req)) {
 311                         __blk_end_request_all(req, -EIO);
 312                         continue;
 313                 }
 314
 315                 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
 316                          "(%u/%u) buffer:%p [%s]\n",
 317                          req, req->cmd, (unsigned long)blk_rq_pos(req),
 318                          blk_rq_cur_sectors(req), blk_rq_sectors(req),
 319                          req->buffer, rq_data_dir(req) ? "write" : "read");
 320
 321                 if (blkif_queue_request(req)) {
 322                         blk_requeue_request(rq, req);
 323 wait:
 324                         /* Avoid pointless unplugs. */
 325                         blk_stop_queue(rq);
 326                         break;
 327                 }
 328
 329                 queued++;
 330         }
 331
 332         if (queued != 0)
 333                 flush_requests(info);
 334 }
 335
 336 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
 337 {
 338         struct request_queue *rq;
 339
 340         rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
 341         if (rq == NULL)
 342                 return -1;
 343
 344         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
 345
 346         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 347         blk_queue_logical_block_size(rq, sector_size);
 348         blk_queue_max_sectors(rq, 512);
 349
 350         /* Each segment in a request is up to an aligned page in size. */
 351         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 352         blk_queue_max_segment_size(rq, PAGE_SIZE);
 353
 354         /* Ensure a merged request will fit in a single I/O ring slot. */
 355         blk_queue_max_phys_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 356         blk_queue_max_hw_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 357
 358         /* Make sure buffer addresses are sector-aligned. */
 359         blk_queue_dma_alignment(rq, 511);
 360
 361         /* Make sure we don't use bounce buffers. */
 362         blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
 363
 364         gd->queue = rq;
 365
 366         return 0;
 367 }
 368
 369
 370 static int xlvbd_barrier(struct blkfront_info *info)
 371 {
 372         int err;
 373
 374         err = blk_queue_ordered(info->rq,
 375                                 info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE,
 376                                 NULL);
 377
 378         if (err)
 379                 return err;
 380
 381         printk(KERN_INFO "blkfront: %s: barriers %s\n",
 382                info->gd->disk_name,
 383                info->feature_barrier ? "enabled" : "disabled");
 384         return 0;
 385 }
 386
 387
 388 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 389                                struct blkfront_info *info,
 390                                u16 vdisk_info, u16 sector_size)
 391 {
 392         struct gendisk *gd;
 393         int nr_minors = 1;
 394         int err = -ENODEV;
 395         unsigned int offset;
 396         int minor;
 397         int nr_parts;
 398
 399         BUG_ON(info->gd != NULL);
 400         BUG_ON(info->rq != NULL);
 401
 402         if ((info->vdevice>>EXT_SHIFT) > 1) {
 403                 /* this is above the extended range; something is wrong */
 404                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
 405                 return -ENODEV;
 406         }
 407
 408         if (!VDEV_IS_EXTENDED(info->vdevice)) {
 409                 minor = BLKIF_MINOR(info->vdevice);
 410                 nr_parts = PARTS_PER_DISK;
 411         } else {
 412                 minor = BLKIF_MINOR_EXT(info->vdevice);
 413                 nr_parts = PARTS_PER_EXT_DISK;
 414         }
 415
 416         if ((minor % nr_parts) == 0)
 417                 nr_minors = nr_parts;
 418
 419         gd = alloc_disk(nr_minors);
 420         if (gd == NULL)
 421                 goto out;
 422
 423         offset = minor / nr_parts;
 424
 425         if (nr_minors > 1) {
 426                 if (offset < 26)
 427                         sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
 428                 else
 429                         sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
 430                                 'a' + ((offset / 26)-1), 'a' + (offset % 26));
 431         } else {
 432                 if (offset < 26)
 433                         sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
 434                                 'a' + offset,
 435                                 minor & (nr_parts - 1));
 436                 else
 437                         sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
 438                                 'a' + ((offset / 26) - 1),
 439                                 'a' + (offset % 26),
 440                                 minor & (nr_parts - 1));
 441         }
 442
 443         gd->major = XENVBD_MAJOR;
 444         gd->first_minor = minor;
 445         gd->fops = &xlvbd_block_fops;
 446         gd->private_data = info;
 447         gd->driverfs_dev = &(info->xbdev->dev);
 448         set_capacity(gd, capacity);
 449
 450         if (xlvbd_init_blk_queue(gd, sector_size)) {
 451                 del_gendisk(gd);
 452                 goto out;
 453         }
 454
 455         info->rq = gd->queue;
 456         info->gd = gd;
 457
 458         if (info->feature_barrier)
 459                 xlvbd_barrier(info);
 460
 461         if (vdisk_info & VDISK_READONLY)
 462                 set_disk_ro(gd, 1);
 463
 464         if (vdisk_info & VDISK_REMOVABLE)
 465                 gd->flags |= GENHD_FL_REMOVABLE;
 466
 467         if (vdisk_info & VDISK_CDROM)
 468                 gd->flags |= GENHD_FL_CD;
 469
 470         return 0;
 471
 472  out:
 473         return err;
 474 }
 475
 476 static void kick_pending_request_queues(struct blkfront_info *info)
 477 {
 478         if (!RING_FULL(&info->ring)) {
 479                 /* Re-enable calldowns. */
 480                 blk_start_queue(info->rq);
 481                 /* Kick things off immediately. */
 482                 do_blkif_request(info->rq);
 483         }
 484 }
 485
 486 static void blkif_restart_queue(struct work_struct *work)
 487 {
 488         struct blkfront_info *info = container_of(work, struct blkfront_info, work);
 489
 490         spin_lock_irq(&blkif_io_lock);
 491         if (info->connected == BLKIF_STATE_CONNECTED)
 492                 kick_pending_request_queues(info);
 493         spin_unlock_irq(&blkif_io_lock);
 494 }
 495
 496 static void blkif_free(struct blkfront_info *info, int suspend)
 497 {
 498         /* Prevent new requests being issued until we fix things up. */
 499         spin_lock_irq(&blkif_io_lock);
 500         info->connected = suspend ?
 501                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
 502         /* No more blkif_request(). */
 503         if (info->rq)
 504                 blk_stop_queue(info->rq);
 505         /* No more gnttab callback work. */
 506         gnttab_cancel_free_callback(&info->callback);
 507         spin_unlock_irq(&blkif_io_lock);
 508
 509         /* Flush gnttab callback work. Must be done with no locks held. */
 510         flush_scheduled_work();
 511
 512         /* Free resources associated with old device channel. */
 513         if (info->ring_ref != GRANT_INVALID_REF) {
 514                 gnttab_end_foreign_access(info->ring_ref, 0,
 515                                           (unsigned long)info->ring.sring);
 516                 info->ring_ref = GRANT_INVALID_REF;
 517                 info->ring.sring = NULL;
 518         }
 519         if (info->irq)
 520                 unbind_from_irqhandler(info->irq, info);
 521         info->evtchn = info->irq = 0;
 522
 523 }
 524
 525 static void blkif_completion(struct blk_shadow *s)
 526 {
 527         int i;
 528         for (i = 0; i < s->req.nr_segments; i++)
 529                 gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL);
 530 }
 531
 532 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 533 {
 534         struct request *req;
 535         struct blkif_response *bret;
 536         RING_IDX i, rp;
 537         unsigned long flags;
 538         struct blkfront_info *info = (struct blkfront_info *)dev_id;
 539         int error;
 540
 541         spin_lock_irqsave(&blkif_io_lock, flags);
 542
 543         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
 544                 spin_unlock_irqrestore(&blkif_io_lock, flags);
 545                 return IRQ_HANDLED;
 546         }
 547
 548  again:
 549         rp = info->ring.sring->rsp_prod;
 550         rmb(); /* Ensure we see queued responses up to 'rp'. */
 551
 552         for (i = info->ring.rsp_cons; i != rp; i++) {
 553                 unsigned long id;
 554
 555                 bret = RING_GET_RESPONSE(&info->ring, i);
 556                 id   = bret->id;
 557                 req  = (struct request *)info->shadow[id].request;
 558
 559                 blkif_completion(&info->shadow[id]);
 560
 561                 add_id_to_freelist(info, id);
 562
 563                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
 564                 switch (bret->operation) {
 565                 case BLKIF_OP_WRITE_BARRIER:
 566                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
 567                                 printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
 568                                        info->gd->disk_name);
 569                                 error = -EOPNOTSUPP;
 570                                 info->feature_barrier = 0;
 571                                 xlvbd_barrier(info);
 572                         }
 573                         /* fall through */
 574                 case BLKIF_OP_READ:
 575                 case BLKIF_OP_WRITE:
 576                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
 577                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
 578                                         "request: %x\n", bret->status);
 579
 580                         __blk_end_request_all(req, error);
 581                         break;
 582                 default:
 583                         BUG();
 584                 }
 585         }
 586
 587         info->ring.rsp_cons = i;
 588
 589         if (i != info->ring.req_prod_pvt) {
 590                 int more_to_do;
 591                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
 592                 if (more_to_do)
 593                         goto again;
 594         } else
 595                 info->ring.sring->rsp_event = i + 1;
 596
 597         kick_pending_request_queues(info);
 598
 599         spin_unlock_irqrestore(&blkif_io_lock, flags);
 600
 601         return IRQ_HANDLED;
 602 }
 603
 604
 605 static int setup_blkring(struct xenbus_device *dev,
 606                          struct blkfront_info *info)
 607 {
 608         struct blkif_sring *sring;
 609         int err;
 610
 611         info->ring_ref = GRANT_INVALID_REF;
 612
 613         sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
 614         if (!sring) {
 615                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
 616                 return -ENOMEM;
 617         }
 618         SHARED_RING_INIT(sring);
 619         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 620
 621         sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 622
 623         err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
 624         if (err < 0) {
 625                 free_page((unsigned long)sring);
 626                 info->ring.sring = NULL;
 627                 goto fail;
 628         }
 629         info->ring_ref = err;
 630
 631         err = xenbus_alloc_evtchn(dev, &info->evtchn);
 632         if (err)
 633                 goto fail;
 634
 635         err = bind_evtchn_to_irqhandler(info->evtchn,
 636                                         blkif_interrupt,
 637                                         IRQF_SAMPLE_RANDOM, "blkif", info);
 638         if (err <= 0) {
 639                 xenbus_dev_fatal(dev, err,
 640                                  "bind_evtchn_to_irqhandler failed");
 641                 goto fail;
 642         }
 643         info->irq = err;
 644
 645         return 0;
 646 fail:
 647         blkif_free(info, 0);
 648         return err;
 649 }
 650
 651
 652 /* Common code used when first setting up, and when resuming. */
 653 static int talk_to_backend(struct xenbus_device *dev,
 654                            struct blkfront_info *info)
 655 {
 656         const char *message = NULL;
 657         struct xenbus_transaction xbt;
 658         int err;
 659
 660         /* Create shared ring, alloc event channel. */
 661         err = setup_blkring(dev, info);
 662         if (err)
 663                 goto out;
 664
 665 again:
 666         err = xenbus_transaction_start(&xbt);
 667         if (err) {
 668                 xenbus_dev_fatal(dev, err, "starting transaction");
 669                 goto destroy_blkring;
 670         }
 671
 672         err = xenbus_printf(xbt, dev->nodename,
 673                             "ring-ref", "%u", info->ring_ref);
 674         if (err) {
 675                 message = "writing ring-ref";
 676                 goto abort_transaction;
 677         }
 678         err = xenbus_printf(xbt, dev->nodename,
 679                             "event-channel", "%u", info->evtchn);
 680         if (err) {
 681                 message = "writing event-channel";
 682                 goto abort_transaction;
 683         }
 684         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
 685                             XEN_IO_PROTO_ABI_NATIVE);
 686         if (err) {
 687                 message = "writing protocol";
 688                 goto abort_transaction;
 689         }
 690
 691         err = xenbus_transaction_end(xbt, 0);
 692         if (err) {
 693                 if (err == -EAGAIN)
 694                         goto again;
 695                 xenbus_dev_fatal(dev, err, "completing transaction");
 696                 goto destroy_blkring;
 697         }
 698
 699         xenbus_switch_state(dev, XenbusStateInitialised);
 700
 701         return 0;
 702
 703  abort_transaction:
 704         xenbus_transaction_end(xbt, 1);
 705         if (message)
 706                 xenbus_dev_fatal(dev, err, "%s", message);
 707  destroy_blkring:
 708         blkif_free(info, 0);
 709  out:
 710         return err;
 711 }
 712
 713
 714 /**
 715  * Entry point to this code when a new device is created.  Allocate the basic
 716  * structures and the ring buffer for communication with the backend, and
 717  * inform the backend of the appropriate details for those.  Switch to
 718  * Initialised state.
 719  */
 720 static int blkfront_probe(struct xenbus_device *dev,
 721                           const struct xenbus_device_id *id)
 722 {
 723         int err, vdevice, i;
 724         struct blkfront_info *info;
 725
 726         /* FIXME: Use dynamic device id if this is not set. */
 727         err = xenbus_scanf(XBT_NIL, dev->nodename,
 728                            "virtual-device", "%i", &vdevice);
 729         if (err != 1) {
 730                 /* go looking in the extended area instead */
 731                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
 732                                    "%i", &vdevice);
 733                 if (err != 1) {
 734                         xenbus_dev_fatal(dev, err, "reading virtual-device");
 735                         return err;
 736                 }
 737         }
 738
 739         info = kzalloc(sizeof(*info), GFP_KERNEL);
 740         if (!info) {
 741                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
 742                 return -ENOMEM;
 743         }
 744
 745         info->xbdev = dev;
 746         info->vdevice = vdevice;
 747         info->connected = BLKIF_STATE_DISCONNECTED;
 748         INIT_WORK(&info->work, blkif_restart_queue);
 749
 750         for (i = 0; i < BLK_RING_SIZE; i++)
 751                 info->shadow[i].req.id = i+1;
 752         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
 753
 754         /* Front end dir is a number, which is used as the id. */
 755         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
 756         dev_set_drvdata(&dev->dev, info);
 757
 758         err = talk_to_backend(dev, info);
 759         if (err) {
 760                 kfree(info);
 761                 dev_set_drvdata(&dev->dev, NULL);
 762                 return err;
 763         }
 764
 765         return 0;
 766 }
 767
 768
 769 static int blkif_recover(struct blkfront_info *info)
 770 {
 771         int i;
 772         struct blkif_request *req;
 773         struct blk_shadow *copy;
 774         int j;
 775
 776         /* Stage 1: Make a safe copy of the shadow state. */
 777         copy = kmalloc(sizeof(info->shadow),
 778                        GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
 779         if (!copy)
 780                 return -ENOMEM;
 781         memcpy(copy, info->shadow, sizeof(info->shadow));
 782
 783         /* Stage 2: Set up free list. */
 784         memset(&info->shadow, 0, sizeof(info->shadow));
 785         for (i = 0; i < BLK_RING_SIZE; i++)
 786                 info->shadow[i].req.id = i+1;
 787         info->shadow_free = info->ring.req_prod_pvt;
 788         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
 789
 790         /* Stage 3: Find pending requests and requeue them. */
 791         for (i = 0; i < BLK_RING_SIZE; i++) {
 792                 /* Not in use? */
 793                 if (copy[i].request == 0)
 794                         continue;
 795
 796                 /* Grab a request slot and copy shadow state into it. */
 797                 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
 798                 *req = copy[i].req;
 799
 800                 /* We get a new request id, and must reset the shadow state. */
 801                 req->id = get_id_from_freelist(info);
 802                 memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
 803
 804                 /* Rewrite any grant references invalidated by susp/resume. */
 805                 for (j = 0; j < req->nr_segments; j++)
 806                         gnttab_grant_foreign_access_ref(
 807                                 req->seg[j].gref,
 808                                 info->xbdev->otherend_id,
 809                                 pfn_to_mfn(info->shadow[req->id].frame[j]),
 810                                 rq_data_dir(
 811                                         (struct request *)
 812                                         info->shadow[req->id].request));
 813                 info->shadow[req->id].req = *req;
 814
 815                 info->ring.req_prod_pvt++;
 816         }
 817
 818         kfree(copy);
 819
 820         xenbus_switch_state(info->xbdev, XenbusStateConnected);
 821
 822         spin_lock_irq(&blkif_io_lock);
 823
 824         /* Now safe for us to use the shared ring */
 825         info->connected = BLKIF_STATE_CONNECTED;
 826
 827         /* Send off requeued requests */
 828         flush_requests(info);
 829
 830         /* Kick any other new requests queued since we resumed */
 831         kick_pending_request_queues(info);
 832
 833         spin_unlock_irq(&blkif_io_lock);
 834
 835         return 0;
 836 }
 837
 838 /**
 839  * We are reconnecting to the backend, due to a suspend/resume, or a backend
 840  * driver restart.  We tear down our blkif structure and recreate it, but
 841  * leave the device-layer structures intact so that this is transparent to the
 842  * rest of the kernel.
 843  */
 844 static int blkfront_resume(struct xenbus_device *dev)
 845 {
 846         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
 847         int err;
 848
 849         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
 850
 851         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
 852
 853         err = talk_to_backend(dev, info);
 854         if (info->connected == BLKIF_STATE_SUSPENDED && !err)
 855                 err = blkif_recover(info);
 856
 857         return err;
 858 }
 859
 860
 861 /*
 862  * Invoked when the backend is finally 'ready' (and has told produced
 863  * the details about the physical device - #sectors, size, etc).
 864  */
 865 static void blkfront_connect(struct blkfront_info *info)
 866 {
 867         unsigned long long sectors;
 868         unsigned long sector_size;
 869         unsigned int binfo;
 870         int err;
 871
 872         if ((info->connected == BLKIF_STATE_CONNECTED) ||
 873             (info->connected == BLKIF_STATE_SUSPENDED) )
 874                 return;
 875
 876         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
 877                 __func__, info->xbdev->otherend);
 878
 879         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
 880                             "sectors", "%llu", &sectors,
 881                             "info", "%u", &binfo,
 882                             "sector-size", "%lu", &sector_size,
 883                             NULL);
 884         if (err) {
 885                 xenbus_dev_fatal(info->xbdev, err,
 886                                  "reading backend fields at %s",
 887                                  info->xbdev->otherend);
 888                 return;
 889         }
 890
 891         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
 892                             "feature-barrier", "%lu", &info->feature_barrier,
 893                             NULL);
 894         if (err)
 895                 info->feature_barrier = 0;
 896
 897         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
 898         if (err) {
 899                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
 900                                  info->xbdev->otherend);
 901                 return;
 902         }
 903
 904         xenbus_switch_state(info->xbdev, XenbusStateConnected);
 905
 906         /* Kick pending requests. */
 907         spin_lock_irq(&blkif_io_lock);
 908         info->connected = BLKIF_STATE_CONNECTED;
 909         kick_pending_request_queues(info);
 910         spin_unlock_irq(&blkif_io_lock);
 911
 912         add_disk(info->gd);
 913
 914         info->is_ready = 1;
 915 }
 916
 917 /**
 918  * Handle the change of state of the backend to Closing.  We must delete our
 919  * device-layer structures now, to ensure that writes are flushed through to
 920  * the backend.  Once is this done, we can switch to Closed in
 921  * acknowledgement.
 922  */
 923 static void blkfront_closing(struct xenbus_device *dev)
 924 {
 925         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
 926         unsigned long flags;
 927
 928         dev_dbg(&dev->dev, "blkfront_closing: %s removed\n", dev->nodename);
 929
 930         if (info->rq == NULL)
 931                 goto out;
 932
 933         spin_lock_irqsave(&blkif_io_lock, flags);
 934
 935         /* No more blkif_request(). */
 936         blk_stop_queue(info->rq);
 937
 938         /* No more gnttab callback work. */
 939         gnttab_cancel_free_callback(&info->callback);
 940         spin_unlock_irqrestore(&blkif_io_lock, flags);
 941
 942         /* Flush gnttab callback work. Must be done with no locks held. */
 943         flush_scheduled_work();
 944
 945         blk_cleanup_queue(info->rq);
 946         info->rq = NULL;
 947
 948         del_gendisk(info->gd);
 949
 950  out:
 951         xenbus_frontend_closed(dev);
 952 }
 953
 954 /**
 955  * Callback received when the backend's state changes.
 956  */
 957 static void backend_changed(struct xenbus_device *dev,
 958                             enum xenbus_state backend_state)
 959 {
 960         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
 961         struct block_device *bd;
 962
 963         dev_dbg(&dev->dev, "blkfront:backend_changed.\n");
 964
 965         switch (backend_state) {
 966         case XenbusStateInitialising:
 967         case XenbusStateInitWait:
 968         case XenbusStateInitialised:
 969         case XenbusStateUnknown:
 970         case XenbusStateClosed:
 971                 break;
 972
 973         case XenbusStateConnected:
 974                 blkfront_connect(info);
 975                 break;
 976
 977         case XenbusStateClosing:
 978                 if (info->gd == NULL) {
 979                         xenbus_frontend_closed(dev);
 980                         break;
 981                 }
 982                 bd = bdget_disk(info->gd, 0);
 983                 if (bd == NULL)
 984                         xenbus_dev_fatal(dev, -ENODEV, "bdget failed");
 985
 986                 mutex_lock(&bd->bd_mutex);
 987                 if (info->users > 0)
 988                         xenbus_dev_error(dev, -EBUSY,
 989                                          "Device in use; refusing to close");
 990                 else
 991                         blkfront_closing(dev);
 992                 mutex_unlock(&bd->bd_mutex);
 993                 bdput(bd);
 994                 break;
 995         }
 996 }
 997
 998 static int blkfront_remove(struct xenbus_device *dev)
 999 {
1000         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1001
1002         dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename);
1003
1004         blkif_free(info, 0);
1005
1006         kfree(info);
1007
1008         return 0;
1009 }
1010
1011 static int blkfront_is_ready(struct xenbus_device *dev)
1012 {
1013         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1014
1015         return info->is_ready;
1016 }
1017
1018 static int blkif_open(struct block_device *bdev, fmode_t mode)
1019 {
1020         struct blkfront_info *info = bdev->bd_disk->private_data;
1021         info->users++;
1022         return 0;
1023 }
1024
1025 static int blkif_release(struct gendisk *disk, fmode_t mode)
1026 {
1027         struct blkfront_info *info = disk->private_data;
1028         info->users--;
1029         if (info->users == 0) {
1030                 /* Check whether we have been instructed to close.  We will
1031                    have ignored this request initially, as the device was
1032                    still mounted. */
1033                 struct xenbus_device *dev = info->xbdev;
1034                 enum xenbus_state state = xenbus_read_driver_state(dev->otherend);
1035
1036                 if (state == XenbusStateClosing && info->is_ready)
1037                         blkfront_closing(dev);
1038         }
1039         return 0;
1040 }
1041
1042 static struct block_device_operations xlvbd_block_fops =
1043 {
1044         .owner = THIS_MODULE,
1045         .open = blkif_open,
1046         .release = blkif_release,
1047         .getgeo = blkif_getgeo,
1048         .locked_ioctl = blkif_ioctl,
1049 };
1050
1051
1052 static struct xenbus_device_id blkfront_ids[] = {
1053         { "vbd" },
1054         { "" }
1055 };
1056
1057 static struct xenbus_driver blkfront = {
1058         .name = "vbd",
1059         .owner = THIS_MODULE,
1060         .ids = blkfront_ids,
1061         .probe = blkfront_probe,
1062         .remove = blkfront_remove,
1063         .resume = blkfront_resume,
1064         .otherend_changed = backend_changed,
1065         .is_ready = blkfront_is_ready,
1066 };
1067
1068 static int __init xlblk_init(void)
1069 {
1070         if (!xen_domain())
1071                 return -ENODEV;
1072
1073         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1074                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1075                        XENVBD_MAJOR, DEV_NAME);
1076                 return -ENODEV;
1077         }
1078
1079         return xenbus_register_frontend(&blkfront);
1080 }
1081 module_init(xlblk_init);
1082
1083
1084 static void __exit xlblk_exit(void)
1085 {
1086         return xenbus_unregister_driver(&blkfront);
1087 }
1088 module_exit(xlblk_exit);
1089
1090 MODULE_DESCRIPTION("Xen virtual block device frontend");
1091 MODULE_LICENSE("GPL");
1092 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1093 MODULE_ALIAS("xen:vbd");
1094 MODULE_ALIAS("xenblk");