Pileus Git - ~andy/linux/blob - 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/slab.h>
  44 #include <linux/smp_lock.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
  53 #include <xen/interface/grant_table.h>
  54 #include <xen/interface/io/blkif.h>
  55 #include <xen/interface/io/protocols.h>
  56
  57 #include <asm/xen/hypervisor.h>
  58
  59 enum blkif_state {
  60         BLKIF_STATE_DISCONNECTED,
  61         BLKIF_STATE_CONNECTED,
  62         BLKIF_STATE_SUSPENDED,
  63 };
  64
  65 struct blk_shadow {
  66         struct blkif_request req;
  67         unsigned long request;
  68         unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  69 };
  70
  71 static const struct block_device_operations xlvbd_block_fops;
  72
  73 #define BLK_RING_SIZE __RING_SIZE((struct blkif_sring *)0, PAGE_SIZE)
  74
  75 /*
  76  * We have one of these per vbd, whether ide, scsi or 'other'.  They
  77  * hang in private_data off the gendisk structure. We may end up
  78  * putting all kinds of interesting stuff here :-)
  79  */
  80 struct blkfront_info
  81 {
  82         struct xenbus_device *xbdev;
  83         struct gendisk *gd;
  84         int vdevice;
  85         blkif_vdev_t handle;
  86         enum blkif_state connected;
  87         int ring_ref;
  88         struct blkif_front_ring ring;
  89         struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  90         unsigned int evtchn, irq;
  91         struct request_queue *rq;
  92         struct work_struct work;
  93         struct gnttab_free_callback callback;
  94         struct blk_shadow shadow[BLK_RING_SIZE];
  95         unsigned long shadow_free;
  96         int feature_barrier;
  97         int is_ready;
  98
  99         /**
 100          * The number of people holding this device open.  We won't allow a
 101          * hot-unplug unless this is 0.
 102          */
 103         int users;
 104 };
 105
 106 static DEFINE_SPINLOCK(blkif_io_lock);
 107
 108 static unsigned int nr_minors;
 109 static unsigned long *minors;
 110 static DEFINE_SPINLOCK(minor_lock);
 111
 112 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
 113         (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
 114 #define GRANT_INVALID_REF       0
 115
 116 #define PARTS_PER_DISK          16
 117 #define PARTS_PER_EXT_DISK      256
 118
 119 #define BLKIF_MAJOR(dev) ((dev)>>8)
 120 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 121
 122 #define EXT_SHIFT 28
 123 #define EXTENDED (1<<EXT_SHIFT)
 124 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 125 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 126
 127 #define DEV_NAME        "xvd"   /* name in /dev */
 128
 129 static int get_id_from_freelist(struct blkfront_info *info)
 130 {
 131         unsigned long free = info->shadow_free;
 132         BUG_ON(free >= BLK_RING_SIZE);
 133         info->shadow_free = info->shadow[free].req.id;
 134         info->shadow[free].req.id = 0x0fffffee; /* debug */
 135         return free;
 136 }
 137
 138 static void add_id_to_freelist(struct blkfront_info *info,
 139                                unsigned long id)
 140 {
 141         info->shadow[id].req.id  = info->shadow_free;
 142         info->shadow[id].request = 0;
 143         info->shadow_free = id;
 144 }
 145
 146 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 147 {
 148         unsigned int end = minor + nr;
 149         int rc;
 150
 151         if (end > nr_minors) {
 152                 unsigned long *bitmap, *old;
 153
 154                 bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
 155                                  GFP_KERNEL);
 156                 if (bitmap == NULL)
 157                         return -ENOMEM;
 158
 159                 spin_lock(&minor_lock);
 160                 if (end > nr_minors) {
 161                         old = minors;
 162                         memcpy(bitmap, minors,
 163                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 164                         minors = bitmap;
 165                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 166                 } else
 167                         old = bitmap;
 168                 spin_unlock(&minor_lock);
 169                 kfree(old);
 170         }
 171
 172         spin_lock(&minor_lock);
 173         if (find_next_bit(minors, end, minor) >= end) {
 174                 for (; minor < end; ++minor)
 175                         __set_bit(minor, minors);
 176                 rc = 0;
 177         } else
 178                 rc = -EBUSY;
 179         spin_unlock(&minor_lock);
 180
 181         return rc;
 182 }
 183
 184 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 185 {
 186         unsigned int end = minor + nr;
 187
 188         BUG_ON(end > nr_minors);
 189         spin_lock(&minor_lock);
 190         for (; minor < end; ++minor)
 191                 __clear_bit(minor, minors);
 192         spin_unlock(&minor_lock);
 193 }
 194
 195 static void blkif_restart_queue_callback(void *arg)
 196 {
 197         struct blkfront_info *info = (struct blkfront_info *)arg;
 198         schedule_work(&info->work);
 199 }
 200
 201 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 202 {
 203         /* We don't have real geometry info, but let's at least return
 204            values consistent with the size of the device */
 205         sector_t nsect = get_capacity(bd->bd_disk);
 206         sector_t cylinders = nsect;
 207
 208         hg->heads = 0xff;
 209         hg->sectors = 0x3f;
 210         sector_div(cylinders, hg->heads * hg->sectors);
 211         hg->cylinders = cylinders;
 212         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 213                 hg->cylinders = 0xffff;
 214         return 0;
 215 }
 216
 217 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 218                        unsigned command, unsigned long argument)
 219 {
 220         struct blkfront_info *info = bdev->bd_disk->private_data;
 221         int i;
 222
 223         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 224                 command, (long)argument);
 225
 226         switch (command) {
 227         case CDROMMULTISESSION:
 228                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 229                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 230                         if (put_user(0, (char __user *)(argument + i)))
 231                                 return -EFAULT;
 232                 return 0;
 233
 234         case CDROM_GET_CAPABILITY: {
 235                 struct gendisk *gd = info->gd;
 236                 if (gd->flags & GENHD_FL_CD)
 237                         return 0;
 238                 return -EINVAL;
 239         }
 240
 241         default:
 242                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 243                   command);*/
 244                 return -EINVAL; /* same return as native Linux */
 245         }
 246
 247         return 0;
 248 }
 249
 250 /*
 251  * blkif_queue_request
 252  *
 253  * request block io
 254  *
 255  * id: for guest use only.
 256  * operation: BLKIF_OP_{READ,WRITE,PROBE}
 257  * buffer: buffer to read/write into. this should be a
 258  *   virtual address in the guest os.
 259  */
 260 static int blkif_queue_request(struct request *req)
 261 {
 262         struct blkfront_info *info = req->rq_disk->private_data;
 263         unsigned long buffer_mfn;
 264         struct blkif_request *ring_req;
 265         unsigned long id;
 266         unsigned int fsect, lsect;
 267         int i, ref;
 268         grant_ref_t gref_head;
 269         struct scatterlist *sg;
 270
 271         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
 272                 return 1;
 273
 274         if (gnttab_alloc_grant_references(
 275                 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
 276                 gnttab_request_free_callback(
 277                         &info->callback,
 278                         blkif_restart_queue_callback,
 279                         info,
 280                         BLKIF_MAX_SEGMENTS_PER_REQUEST);
 281                 return 1;
 282         }
 283
 284         /* Fill out a communications ring structure. */
 285         ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
 286         id = get_id_from_freelist(info);
 287         info->shadow[id].request = (unsigned long)req;
 288
 289         ring_req->id = id;
 290         ring_req->sector_number = (blkif_sector_t)blk_rq_pos(req);
 291         ring_req->handle = info->handle;
 292
 293         ring_req->operation = rq_data_dir(req) ?
 294                 BLKIF_OP_WRITE : BLKIF_OP_READ;
 295         if (req->cmd_flags & REQ_HARDBARRIER)
 296                 ring_req->operation = BLKIF_OP_WRITE_BARRIER;
 297
 298         ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
 299         BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
 300
 301         for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
 302                 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
 303                 fsect = sg->offset >> 9;
 304                 lsect = fsect + (sg->length >> 9) - 1;
 305                 /* install a grant reference. */
 306                 ref = gnttab_claim_grant_reference(&gref_head);
 307                 BUG_ON(ref == -ENOSPC);
 308
 309                 gnttab_grant_foreign_access_ref(
 310                                 ref,
 311                                 info->xbdev->otherend_id,
 312                                 buffer_mfn,
 313                                 rq_data_dir(req) );
 314
 315                 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
 316                 ring_req->seg[i] =
 317                                 (struct blkif_request_segment) {
 318                                         .gref       = ref,
 319                                         .first_sect = fsect,
 320                                         .last_sect  = lsect };
 321         }
 322
 323         info->ring.req_prod_pvt++;
 324
 325         /* Keep a private copy so we can reissue requests when recovering. */
 326         info->shadow[id].req = *ring_req;
 327
 328         gnttab_free_grant_references(gref_head);
 329
 330         return 0;
 331 }
 332
 333
 334 static inline void flush_requests(struct blkfront_info *info)
 335 {
 336         int notify;
 337
 338         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
 339
 340         if (notify)
 341                 notify_remote_via_irq(info->irq);
 342 }
 343
 344 /*
 345  * do_blkif_request
 346  *  read a block; request is in a request queue
 347  */
 348 static void do_blkif_request(struct request_queue *rq)
 349 {
 350         struct blkfront_info *info = NULL;
 351         struct request *req;
 352         int queued;
 353
 354         pr_debug("Entered do_blkif_request\n");
 355
 356         queued = 0;
 357
 358         while ((req = blk_peek_request(rq)) != NULL) {
 359                 info = req->rq_disk->private_data;
 360
 361                 if (RING_FULL(&info->ring))
 362                         goto wait;
 363
 364                 blk_start_request(req);
 365
 366                 if (req->cmd_type != REQ_TYPE_FS) {
 367                         __blk_end_request_all(req, -EIO);
 368                         continue;
 369                 }
 370
 371                 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
 372                          "(%u/%u) buffer:%p [%s]\n",
 373                          req, req->cmd, (unsigned long)blk_rq_pos(req),
 374                          blk_rq_cur_sectors(req), blk_rq_sectors(req),
 375                          req->buffer, rq_data_dir(req) ? "write" : "read");
 376
 377                 if (blkif_queue_request(req)) {
 378                         blk_requeue_request(rq, req);
 379 wait:
 380                         /* Avoid pointless unplugs. */
 381                         blk_stop_queue(rq);
 382                         break;
 383                 }
 384
 385                 queued++;
 386         }
 387
 388         if (queued != 0)
 389                 flush_requests(info);
 390 }
 391
 392 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
 393 {
 394         struct request_queue *rq;
 395
 396         rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
 397         if (rq == NULL)
 398                 return -1;
 399
 400         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
 401
 402         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 403         blk_queue_logical_block_size(rq, sector_size);
 404         blk_queue_max_hw_sectors(rq, 512);
 405
 406         /* Each segment in a request is up to an aligned page in size. */
 407         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 408         blk_queue_max_segment_size(rq, PAGE_SIZE);
 409
 410         /* Ensure a merged request will fit in a single I/O ring slot. */
 411         blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 412
 413         /* Make sure buffer addresses are sector-aligned. */
 414         blk_queue_dma_alignment(rq, 511);
 415
 416         /* Make sure we don't use bounce buffers. */
 417         blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
 418
 419         gd->queue = rq;
 420
 421         return 0;
 422 }
 423
 424
 425 static int xlvbd_barrier(struct blkfront_info *info)
 426 {
 427         int err;
 428
 429         err = blk_queue_ordered(info->rq,
 430                                 info->feature_barrier ? QUEUE_ORDERED_DRAIN : QUEUE_ORDERED_NONE);
 431
 432         if (err)
 433                 return err;
 434
 435         printk(KERN_INFO "blkfront: %s: barriers %s\n",
 436                info->gd->disk_name,
 437                info->feature_barrier ? "enabled" : "disabled");
 438         return 0;
 439 }
 440
 441
 442 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 443                                struct blkfront_info *info,
 444                                u16 vdisk_info, u16 sector_size)
 445 {
 446         struct gendisk *gd;
 447         int nr_minors = 1;
 448         int err = -ENODEV;
 449         unsigned int offset;
 450         int minor;
 451         int nr_parts;
 452
 453         BUG_ON(info->gd != NULL);
 454         BUG_ON(info->rq != NULL);
 455
 456         if ((info->vdevice>>EXT_SHIFT) > 1) {
 457                 /* this is above the extended range; something is wrong */
 458                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
 459                 return -ENODEV;
 460         }
 461
 462         if (!VDEV_IS_EXTENDED(info->vdevice)) {
 463                 minor = BLKIF_MINOR(info->vdevice);
 464                 nr_parts = PARTS_PER_DISK;
 465         } else {
 466                 minor = BLKIF_MINOR_EXT(info->vdevice);
 467                 nr_parts = PARTS_PER_EXT_DISK;
 468         }
 469
 470         if ((minor % nr_parts) == 0)
 471                 nr_minors = nr_parts;
 472
 473         err = xlbd_reserve_minors(minor, nr_minors);
 474         if (err)
 475                 goto out;
 476         err = -ENODEV;
 477
 478         gd = alloc_disk(nr_minors);
 479         if (gd == NULL)
 480                 goto release;
 481
 482         offset = minor / nr_parts;
 483
 484         if (nr_minors > 1) {
 485                 if (offset < 26)
 486                         sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
 487                 else
 488                         sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
 489                                 'a' + ((offset / 26)-1), 'a' + (offset % 26));
 490         } else {
 491                 if (offset < 26)
 492                         sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
 493                                 'a' + offset,
 494                                 minor & (nr_parts - 1));
 495                 else
 496                         sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
 497                                 'a' + ((offset / 26) - 1),
 498                                 'a' + (offset % 26),
 499                                 minor & (nr_parts - 1));
 500         }
 501
 502         gd->major = XENVBD_MAJOR;
 503         gd->first_minor = minor;
 504         gd->fops = &xlvbd_block_fops;
 505         gd->private_data = info;
 506         gd->driverfs_dev = &(info->xbdev->dev);
 507         set_capacity(gd, capacity);
 508
 509         if (xlvbd_init_blk_queue(gd, sector_size)) {
 510                 del_gendisk(gd);
 511                 goto release;
 512         }
 513
 514         info->rq = gd->queue;
 515         info->gd = gd;
 516
 517         if (info->feature_barrier)
 518                 xlvbd_barrier(info);
 519
 520         if (vdisk_info & VDISK_READONLY)
 521                 set_disk_ro(gd, 1);
 522
 523         if (vdisk_info & VDISK_REMOVABLE)
 524                 gd->flags |= GENHD_FL_REMOVABLE;
 525
 526         if (vdisk_info & VDISK_CDROM)
 527                 gd->flags |= GENHD_FL_CD;
 528
 529         return 0;
 530
 531  release:
 532         xlbd_release_minors(minor, nr_minors);
 533  out:
 534         return err;
 535 }
 536
 537 static void kick_pending_request_queues(struct blkfront_info *info)
 538 {
 539         if (!RING_FULL(&info->ring)) {
 540                 /* Re-enable calldowns. */
 541                 blk_start_queue(info->rq);
 542                 /* Kick things off immediately. */
 543                 do_blkif_request(info->rq);
 544         }
 545 }
 546
 547 static void blkif_restart_queue(struct work_struct *work)
 548 {
 549         struct blkfront_info *info = container_of(work, struct blkfront_info, work);
 550
 551         spin_lock_irq(&blkif_io_lock);
 552         if (info->connected == BLKIF_STATE_CONNECTED)
 553                 kick_pending_request_queues(info);
 554         spin_unlock_irq(&blkif_io_lock);
 555 }
 556
 557 static void blkif_free(struct blkfront_info *info, int suspend)
 558 {
 559         /* Prevent new requests being issued until we fix things up. */
 560         spin_lock_irq(&blkif_io_lock);
 561         info->connected = suspend ?
 562                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
 563         /* No more blkif_request(). */
 564         if (info->rq)
 565                 blk_stop_queue(info->rq);
 566         /* No more gnttab callback work. */
 567         gnttab_cancel_free_callback(&info->callback);
 568         spin_unlock_irq(&blkif_io_lock);
 569
 570         /* Flush gnttab callback work. Must be done with no locks held. */
 571         flush_scheduled_work();
 572
 573         /* Free resources associated with old device channel. */
 574         if (info->ring_ref != GRANT_INVALID_REF) {
 575                 gnttab_end_foreign_access(info->ring_ref, 0,
 576                                           (unsigned long)info->ring.sring);
 577                 info->ring_ref = GRANT_INVALID_REF;
 578                 info->ring.sring = NULL;
 579         }
 580         if (info->irq)
 581                 unbind_from_irqhandler(info->irq, info);
 582         info->evtchn = info->irq = 0;
 583
 584 }
 585
 586 static void blkif_completion(struct blk_shadow *s)
 587 {
 588         int i;
 589         for (i = 0; i < s->req.nr_segments; i++)
 590                 gnttab_end_foreign_access(s->req.seg[i].gref, 0, 0UL);
 591 }
 592
 593 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 594 {
 595         struct request *req;
 596         struct blkif_response *bret;
 597         RING_IDX i, rp;
 598         unsigned long flags;
 599         struct blkfront_info *info = (struct blkfront_info *)dev_id;
 600         int error;
 601
 602         spin_lock_irqsave(&blkif_io_lock, flags);
 603
 604         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
 605                 spin_unlock_irqrestore(&blkif_io_lock, flags);
 606                 return IRQ_HANDLED;
 607         }
 608
 609  again:
 610         rp = info->ring.sring->rsp_prod;
 611         rmb(); /* Ensure we see queued responses up to 'rp'. */
 612
 613         for (i = info->ring.rsp_cons; i != rp; i++) {
 614                 unsigned long id;
 615
 616                 bret = RING_GET_RESPONSE(&info->ring, i);
 617                 id   = bret->id;
 618                 req  = (struct request *)info->shadow[id].request;
 619
 620                 blkif_completion(&info->shadow[id]);
 621
 622                 add_id_to_freelist(info, id);
 623
 624                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
 625                 switch (bret->operation) {
 626                 case BLKIF_OP_WRITE_BARRIER:
 627                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
 628                                 printk(KERN_WARNING "blkfront: %s: write barrier op failed\n",
 629                                        info->gd->disk_name);
 630                                 error = -EOPNOTSUPP;
 631                                 info->feature_barrier = 0;
 632                                 xlvbd_barrier(info);
 633                         }
 634                         /* fall through */
 635                 case BLKIF_OP_READ:
 636                 case BLKIF_OP_WRITE:
 637                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
 638                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
 639                                         "request: %x\n", bret->status);
 640
 641                         __blk_end_request_all(req, error);
 642                         break;
 643                 default:
 644                         BUG();
 645                 }
 646         }
 647
 648         info->ring.rsp_cons = i;
 649
 650         if (i != info->ring.req_prod_pvt) {
 651                 int more_to_do;
 652                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
 653                 if (more_to_do)
 654                         goto again;
 655         } else
 656                 info->ring.sring->rsp_event = i + 1;
 657
 658         kick_pending_request_queues(info);
 659
 660         spin_unlock_irqrestore(&blkif_io_lock, flags);
 661
 662         return IRQ_HANDLED;
 663 }
 664
 665
 666 static int setup_blkring(struct xenbus_device *dev,
 667                          struct blkfront_info *info)
 668 {
 669         struct blkif_sring *sring;
 670         int err;
 671
 672         info->ring_ref = GRANT_INVALID_REF;
 673
 674         sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
 675         if (!sring) {
 676                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
 677                 return -ENOMEM;
 678         }
 679         SHARED_RING_INIT(sring);
 680         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 681
 682         sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 683
 684         err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
 685         if (err < 0) {
 686                 free_page((unsigned long)sring);
 687                 info->ring.sring = NULL;
 688                 goto fail;
 689         }
 690         info->ring_ref = err;
 691
 692         err = xenbus_alloc_evtchn(dev, &info->evtchn);
 693         if (err)
 694                 goto fail;
 695
 696         err = bind_evtchn_to_irqhandler(info->evtchn,
 697                                         blkif_interrupt,
 698                                         IRQF_SAMPLE_RANDOM, "blkif", info);
 699         if (err <= 0) {
 700                 xenbus_dev_fatal(dev, err,
 701                                  "bind_evtchn_to_irqhandler failed");
 702                 goto fail;
 703         }
 704         info->irq = err;
 705
 706         return 0;
 707 fail:
 708         blkif_free(info, 0);
 709         return err;
 710 }
 711
 712
 713 /* Common code used when first setting up, and when resuming. */
 714 static int talk_to_blkback(struct xenbus_device *dev,
 715                            struct blkfront_info *info)
 716 {
 717         const char *message = NULL;
 718         struct xenbus_transaction xbt;
 719         int err;
 720
 721         /* Create shared ring, alloc event channel. */
 722         err = setup_blkring(dev, info);
 723         if (err)
 724                 goto out;
 725
 726 again:
 727         err = xenbus_transaction_start(&xbt);
 728         if (err) {
 729                 xenbus_dev_fatal(dev, err, "starting transaction");
 730                 goto destroy_blkring;
 731         }
 732
 733         err = xenbus_printf(xbt, dev->nodename,
 734                             "ring-ref", "%u", info->ring_ref);
 735         if (err) {
 736                 message = "writing ring-ref";
 737                 goto abort_transaction;
 738         }
 739         err = xenbus_printf(xbt, dev->nodename,
 740                             "event-channel", "%u", info->evtchn);
 741         if (err) {
 742                 message = "writing event-channel";
 743                 goto abort_transaction;
 744         }
 745         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
 746                             XEN_IO_PROTO_ABI_NATIVE);
 747         if (err) {
 748                 message = "writing protocol";
 749                 goto abort_transaction;
 750         }
 751
 752         err = xenbus_transaction_end(xbt, 0);
 753         if (err) {
 754                 if (err == -EAGAIN)
 755                         goto again;
 756                 xenbus_dev_fatal(dev, err, "completing transaction");
 757                 goto destroy_blkring;
 758         }
 759
 760         xenbus_switch_state(dev, XenbusStateInitialised);
 761
 762         return 0;
 763
 764  abort_transaction:
 765         xenbus_transaction_end(xbt, 1);
 766         if (message)
 767                 xenbus_dev_fatal(dev, err, "%s", message);
 768  destroy_blkring:
 769         blkif_free(info, 0);
 770  out:
 771         return err;
 772 }
 773
 774
 775 /**
 776  * Entry point to this code when a new device is created.  Allocate the basic
 777  * structures and the ring buffer for communication with the backend, and
 778  * inform the backend of the appropriate details for those.  Switch to
 779  * Initialised state.
 780  */
 781 static int blkfront_probe(struct xenbus_device *dev,
 782                           const struct xenbus_device_id *id)
 783 {
 784         int err, vdevice, i;
 785         struct blkfront_info *info;
 786
 787         /* FIXME: Use dynamic device id if this is not set. */
 788         err = xenbus_scanf(XBT_NIL, dev->nodename,
 789                            "virtual-device", "%i", &vdevice);
 790         if (err != 1) {
 791                 /* go looking in the extended area instead */
 792                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
 793                                    "%i", &vdevice);
 794                 if (err != 1) {
 795                         xenbus_dev_fatal(dev, err, "reading virtual-device");
 796                         return err;
 797                 }
 798         }
 799
 800         info = kzalloc(sizeof(*info), GFP_KERNEL);
 801         if (!info) {
 802                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
 803                 return -ENOMEM;
 804         }
 805
 806         info->xbdev = dev;
 807         info->vdevice = vdevice;
 808         info->connected = BLKIF_STATE_DISCONNECTED;
 809         INIT_WORK(&info->work, blkif_restart_queue);
 810
 811         for (i = 0; i < BLK_RING_SIZE; i++)
 812                 info->shadow[i].req.id = i+1;
 813         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
 814
 815         /* Front end dir is a number, which is used as the id. */
 816         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
 817         dev_set_drvdata(&dev->dev, info);
 818
 819         err = talk_to_blkback(dev, info);
 820         if (err) {
 821                 kfree(info);
 822                 dev_set_drvdata(&dev->dev, NULL);
 823                 return err;
 824         }
 825
 826         return 0;
 827 }
 828
 829
 830 static int blkif_recover(struct blkfront_info *info)
 831 {
 832         int i;
 833         struct blkif_request *req;
 834         struct blk_shadow *copy;
 835         int j;
 836
 837         /* Stage 1: Make a safe copy of the shadow state. */
 838         copy = kmalloc(sizeof(info->shadow),
 839                        GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
 840         if (!copy)
 841                 return -ENOMEM;
 842         memcpy(copy, info->shadow, sizeof(info->shadow));
 843
 844         /* Stage 2: Set up free list. */
 845         memset(&info->shadow, 0, sizeof(info->shadow));
 846         for (i = 0; i < BLK_RING_SIZE; i++)
 847                 info->shadow[i].req.id = i+1;
 848         info->shadow_free = info->ring.req_prod_pvt;
 849         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
 850
 851         /* Stage 3: Find pending requests and requeue them. */
 852         for (i = 0; i < BLK_RING_SIZE; i++) {
 853                 /* Not in use? */
 854                 if (copy[i].request == 0)
 855                         continue;
 856
 857                 /* Grab a request slot and copy shadow state into it. */
 858                 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
 859                 *req = copy[i].req;
 860
 861                 /* We get a new request id, and must reset the shadow state. */
 862                 req->id = get_id_from_freelist(info);
 863                 memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
 864
 865                 /* Rewrite any grant references invalidated by susp/resume. */
 866                 for (j = 0; j < req->nr_segments; j++)
 867                         gnttab_grant_foreign_access_ref(
 868                                 req->seg[j].gref,
 869                                 info->xbdev->otherend_id,
 870                                 pfn_to_mfn(info->shadow[req->id].frame[j]),
 871                                 rq_data_dir(
 872                                         (struct request *)
 873                                         info->shadow[req->id].request));
 874                 info->shadow[req->id].req = *req;
 875
 876                 info->ring.req_prod_pvt++;
 877         }
 878
 879         kfree(copy);
 880
 881         xenbus_switch_state(info->xbdev, XenbusStateConnected);
 882
 883         spin_lock_irq(&blkif_io_lock);
 884
 885         /* Now safe for us to use the shared ring */
 886         info->connected = BLKIF_STATE_CONNECTED;
 887
 888         /* Send off requeued requests */
 889         flush_requests(info);
 890
 891         /* Kick any other new requests queued since we resumed */
 892         kick_pending_request_queues(info);
 893
 894         spin_unlock_irq(&blkif_io_lock);
 895
 896         return 0;
 897 }
 898
 899 /**
 900  * We are reconnecting to the backend, due to a suspend/resume, or a backend
 901  * driver restart.  We tear down our blkif structure and recreate it, but
 902  * leave the device-layer structures intact so that this is transparent to the
 903  * rest of the kernel.
 904  */
 905 static int blkfront_resume(struct xenbus_device *dev)
 906 {
 907         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
 908         int err;
 909
 910         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
 911
 912         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
 913
 914         err = talk_to_blkback(dev, info);
 915         if (info->connected == BLKIF_STATE_SUSPENDED && !err)
 916                 err = blkif_recover(info);
 917
 918         return err;
 919 }
 920
 921
 922 /*
 923  * Invoked when the backend is finally 'ready' (and has told produced
 924  * the details about the physical device - #sectors, size, etc).
 925  */
 926 static void blkfront_connect(struct blkfront_info *info)
 927 {
 928         unsigned long long sectors;
 929         unsigned long sector_size;
 930         unsigned int binfo;
 931         int err;
 932
 933         switch (info->connected) {
 934         case BLKIF_STATE_CONNECTED:
 935                 /*
 936                  * Potentially, the back-end may be signalling
 937                  * a capacity change; update the capacity.
 938                  */
 939                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
 940                                    "sectors", "%Lu", &sectors);
 941                 if (XENBUS_EXIST_ERR(err))
 942                         return;
 943                 printk(KERN_INFO "Setting capacity to %Lu\n",
 944                        sectors);
 945                 set_capacity(info->gd, sectors);
 946
 947                 /* fall through */
 948         case BLKIF_STATE_SUSPENDED:
 949                 return;
 950         }
 951
 952         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
 953                 __func__, info->xbdev->otherend);
 954
 955         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
 956                             "sectors", "%llu", &sectors,
 957                             "info", "%u", &binfo,
 958                             "sector-size", "%lu", &sector_size,
 959                             NULL);
 960         if (err) {
 961                 xenbus_dev_fatal(info->xbdev, err,
 962                                  "reading backend fields at %s",
 963                                  info->xbdev->otherend);
 964                 return;
 965         }
 966
 967         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
 968                             "feature-barrier", "%lu", &info->feature_barrier,
 969                             NULL);
 970         if (err)
 971                 info->feature_barrier = 0;
 972
 973         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
 974         if (err) {
 975                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
 976                                  info->xbdev->otherend);
 977                 return;
 978         }
 979
 980         xenbus_switch_state(info->xbdev, XenbusStateConnected);
 981
 982         /* Kick pending requests. */
 983         spin_lock_irq(&blkif_io_lock);
 984         info->connected = BLKIF_STATE_CONNECTED;
 985         kick_pending_request_queues(info);
 986         spin_unlock_irq(&blkif_io_lock);
 987
 988         add_disk(info->gd);
 989
 990         info->is_ready = 1;
 991 }
 992
 993 /**
 994  * Handle the change of state of the backend to Closing.  We must delete our
 995  * device-layer structures now, to ensure that writes are flushed through to
 996  * the backend.  Once is this done, we can switch to Closed in
 997  * acknowledgement.
 998  */
 999 static void blkfront_closing(struct blkfront_info *info)
1000 {
1001         unsigned int minor, nr_minors;
1002         unsigned long flags;
1003
1004
1005         if (info->rq == NULL)
1006                 goto out;
1007
1008         spin_lock_irqsave(&blkif_io_lock, flags);
1009
1010         /* No more blkif_request(). */
1011         blk_stop_queue(info->rq);
1012
1013         /* No more gnttab callback work. */
1014         gnttab_cancel_free_callback(&info->callback);
1015         spin_unlock_irqrestore(&blkif_io_lock, flags);
1016
1017         /* Flush gnttab callback work. Must be done with no locks held. */
1018         flush_scheduled_work();
1019
1020         blk_cleanup_queue(info->rq);
1021         info->rq = NULL;
1022
1023         minor = info->gd->first_minor;
1024         nr_minors = info->gd->minors;
1025         del_gendisk(info->gd);
1026         xlbd_release_minors(minor, nr_minors);
1027
1028  out:
1029         if (info->xbdev)
1030                 xenbus_frontend_closed(info->xbdev);
1031 }
1032
1033 /**
1034  * Callback received when the backend's state changes.
1035  */
1036 static void blkback_changed(struct xenbus_device *dev,
1037                             enum xenbus_state backend_state)
1038 {
1039         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1040         struct block_device *bd;
1041
1042         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1043
1044         switch (backend_state) {
1045         case XenbusStateInitialising:
1046         case XenbusStateInitWait:
1047         case XenbusStateInitialised:
1048         case XenbusStateUnknown:
1049         case XenbusStateClosed:
1050                 break;
1051
1052         case XenbusStateConnected:
1053                 blkfront_connect(info);
1054                 break;
1055
1056         case XenbusStateClosing:
1057                 if (info->gd == NULL) {
1058                         xenbus_frontend_closed(dev);
1059                         break;
1060                 }
1061                 bd = bdget_disk(info->gd, 0);
1062                 if (bd == NULL)
1063                         xenbus_dev_fatal(dev, -ENODEV, "bdget failed");
1064
1065                 mutex_lock(&bd->bd_mutex);
1066                 if (info->users > 0)
1067                         xenbus_dev_error(dev, -EBUSY,
1068                                          "Device in use; refusing to close");
1069                 else
1070                         blkfront_closing(info);
1071                 mutex_unlock(&bd->bd_mutex);
1072                 bdput(bd);
1073                 break;
1074         }
1075 }
1076
1077 static int blkfront_remove(struct xenbus_device *dev)
1078 {
1079         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1080
1081         dev_dbg(&dev->dev, "blkfront_remove: %s removed\n", dev->nodename);
1082
1083         blkif_free(info, 0);
1084
1085         if(info->users == 0)
1086                 kfree(info);
1087         else
1088                 info->xbdev = NULL;
1089
1090         return 0;
1091 }
1092
1093 static int blkfront_is_ready(struct xenbus_device *dev)
1094 {
1095         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1096
1097         return info->is_ready && info->xbdev;
1098 }
1099
1100 static int blkif_open(struct block_device *bdev, fmode_t mode)
1101 {
1102         struct blkfront_info *info = bdev->bd_disk->private_data;
1103
1104         if (!info->xbdev)
1105                 return -ENODEV;
1106
1107         lock_kernel();
1108         info->users++;
1109         unlock_kernel();
1110
1111         return 0;
1112 }
1113
1114 static int blkif_release(struct gendisk *disk, fmode_t mode)
1115 {
1116         struct blkfront_info *info = disk->private_data;
1117         lock_kernel();
1118         info->users--;
1119         if (info->users == 0) {
1120                 /* Check whether we have been instructed to close.  We will
1121                    have ignored this request initially, as the device was
1122                    still mounted. */
1123                 struct xenbus_device *dev = info->xbdev;
1124
1125                 if (!dev) {
1126                         blkfront_closing(info);
1127                         kfree(info);
1128                 } else if (xenbus_read_driver_state(dev->otherend)
1129                            == XenbusStateClosing && info->is_ready)
1130                         blkfront_closing(info);
1131         }
1132         unlock_kernel();
1133         return 0;
1134 }
1135
1136 static const struct block_device_operations xlvbd_block_fops =
1137 {
1138         .owner = THIS_MODULE,
1139         .open = blkif_open,
1140         .release = blkif_release,
1141         .getgeo = blkif_getgeo,
1142         .ioctl = blkif_ioctl,
1143 };
1144
1145
1146 static const struct xenbus_device_id blkfront_ids[] = {
1147         { "vbd" },
1148         { "" }
1149 };
1150
1151 static struct xenbus_driver blkfront = {
1152         .name = "vbd",
1153         .owner = THIS_MODULE,
1154         .ids = blkfront_ids,
1155         .probe = blkfront_probe,
1156         .remove = blkfront_remove,
1157         .resume = blkfront_resume,
1158         .otherend_changed = blkback_changed,
1159         .is_ready = blkfront_is_ready,
1160 };
1161
1162 static int __init xlblk_init(void)
1163 {
1164         if (!xen_domain())
1165                 return -ENODEV;
1166
1167         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1168                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1169                        XENVBD_MAJOR, DEV_NAME);
1170                 return -ENODEV;
1171         }
1172
1173         return xenbus_register_frontend(&blkfront);
1174 }
1175 module_init(xlblk_init);
1176
1177
1178 static void __exit xlblk_exit(void)
1179 {
1180         return xenbus_unregister_driver(&blkfront);
1181 }
1182 module_exit(xlblk_exit);
1183
1184 MODULE_DESCRIPTION("Xen virtual block device frontend");
1185 MODULE_LICENSE("GPL");
1186 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1187 MODULE_ALIAS("xen:vbd");
1188 MODULE_ALIAS("xenblk");