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/mutex.h>
  45 #include <linux/scatterlist.h>
  46
  47 #include <xen/xen.h>
  48 #include <xen/xenbus.h>
  49 #include <xen/grant_table.h>
  50 #include <xen/events.h>
  51 #include <xen/page.h>
  52 #include <xen/platform_pci.h>
  53
  54 #include <xen/interface/grant_table.h>
  55 #include <xen/interface/io/blkif.h>
  56 #include <xen/interface/io/protocols.h>
  57
  58 #include <asm/xen/hypervisor.h>
  59
  60 enum blkif_state {
  61         BLKIF_STATE_DISCONNECTED,
  62         BLKIF_STATE_CONNECTED,
  63         BLKIF_STATE_SUSPENDED,
  64 };
  65
  66 struct blk_shadow {
  67         struct blkif_request req;
  68         struct request *request;
  69         unsigned long frame[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  70 };
  71
  72 static DEFINE_MUTEX(blkfront_mutex);
  73 static const struct block_device_operations xlvbd_block_fops;
  74
  75 #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
  76
  77 /*
  78  * We have one of these per vbd, whether ide, scsi or 'other'.  They
  79  * hang in private_data off the gendisk structure. We may end up
  80  * putting all kinds of interesting stuff here :-)
  81  */
  82 struct blkfront_info
  83 {
  84         struct mutex mutex;
  85         struct xenbus_device *xbdev;
  86         struct gendisk *gd;
  87         int vdevice;
  88         blkif_vdev_t handle;
  89         enum blkif_state connected;
  90         int ring_ref;
  91         struct blkif_front_ring ring;
  92         struct scatterlist sg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
  93         unsigned int evtchn, irq;
  94         struct request_queue *rq;
  95         struct work_struct work;
  96         struct gnttab_free_callback callback;
  97         struct blk_shadow shadow[BLK_RING_SIZE];
  98         unsigned long shadow_free;
  99         unsigned int feature_flush;
 100         unsigned int flush_op;
 101         int is_ready;
 102 };
 103
 104 static DEFINE_SPINLOCK(blkif_io_lock);
 105
 106 static unsigned int nr_minors;
 107 static unsigned long *minors;
 108 static DEFINE_SPINLOCK(minor_lock);
 109
 110 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
 111         (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
 112 #define GRANT_INVALID_REF       0
 113
 114 #define PARTS_PER_DISK          16
 115 #define PARTS_PER_EXT_DISK      256
 116
 117 #define BLKIF_MAJOR(dev) ((dev)>>8)
 118 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 119
 120 #define EXT_SHIFT 28
 121 #define EXTENDED (1<<EXT_SHIFT)
 122 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 123 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 124 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 125 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 126 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 127 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 128
 129 #define DEV_NAME        "xvd"   /* name in /dev */
 130
 131 static int get_id_from_freelist(struct blkfront_info *info)
 132 {
 133         unsigned long free = info->shadow_free;
 134         BUG_ON(free >= BLK_RING_SIZE);
 135         info->shadow_free = info->shadow[free].req.id;
 136         info->shadow[free].req.id = 0x0fffffee; /* debug */
 137         return free;
 138 }
 139
 140 static void add_id_to_freelist(struct blkfront_info *info,
 141                                unsigned long id)
 142 {
 143         info->shadow[id].req.id  = info->shadow_free;
 144         info->shadow[id].request = NULL;
 145         info->shadow_free = id;
 146 }
 147
 148 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 149 {
 150         unsigned int end = minor + nr;
 151         int rc;
 152
 153         if (end > nr_minors) {
 154                 unsigned long *bitmap, *old;
 155
 156                 bitmap = kzalloc(BITS_TO_LONGS(end) * sizeof(*bitmap),
 157                                  GFP_KERNEL);
 158                 if (bitmap == NULL)
 159                         return -ENOMEM;
 160
 161                 spin_lock(&minor_lock);
 162                 if (end > nr_minors) {
 163                         old = minors;
 164                         memcpy(bitmap, minors,
 165                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 166                         minors = bitmap;
 167                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 168                 } else
 169                         old = bitmap;
 170                 spin_unlock(&minor_lock);
 171                 kfree(old);
 172         }
 173
 174         spin_lock(&minor_lock);
 175         if (find_next_bit(minors, end, minor) >= end) {
 176                 for (; minor < end; ++minor)
 177                         __set_bit(minor, minors);
 178                 rc = 0;
 179         } else
 180                 rc = -EBUSY;
 181         spin_unlock(&minor_lock);
 182
 183         return rc;
 184 }
 185
 186 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 187 {
 188         unsigned int end = minor + nr;
 189
 190         BUG_ON(end > nr_minors);
 191         spin_lock(&minor_lock);
 192         for (; minor < end; ++minor)
 193                 __clear_bit(minor, minors);
 194         spin_unlock(&minor_lock);
 195 }
 196
 197 static void blkif_restart_queue_callback(void *arg)
 198 {
 199         struct blkfront_info *info = (struct blkfront_info *)arg;
 200         schedule_work(&info->work);
 201 }
 202
 203 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 204 {
 205         /* We don't have real geometry info, but let's at least return
 206            values consistent with the size of the device */
 207         sector_t nsect = get_capacity(bd->bd_disk);
 208         sector_t cylinders = nsect;
 209
 210         hg->heads = 0xff;
 211         hg->sectors = 0x3f;
 212         sector_div(cylinders, hg->heads * hg->sectors);
 213         hg->cylinders = cylinders;
 214         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 215                 hg->cylinders = 0xffff;
 216         return 0;
 217 }
 218
 219 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 220                        unsigned command, unsigned long argument)
 221 {
 222         struct blkfront_info *info = bdev->bd_disk->private_data;
 223         int i;
 224
 225         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 226                 command, (long)argument);
 227
 228         switch (command) {
 229         case CDROMMULTISESSION:
 230                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 231                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 232                         if (put_user(0, (char __user *)(argument + i)))
 233                                 return -EFAULT;
 234                 return 0;
 235
 236         case CDROM_GET_CAPABILITY: {
 237                 struct gendisk *gd = info->gd;
 238                 if (gd->flags & GENHD_FL_CD)
 239                         return 0;
 240                 return -EINVAL;
 241         }
 242
 243         default:
 244                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 245                   command);*/
 246                 return -EINVAL; /* same return as native Linux */
 247         }
 248
 249         return 0;
 250 }
 251
 252 /*
 253  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 254  * and writes are handled as expected.
 255  *
 256  * @req: a request struct
 257  */
 258 static int blkif_queue_request(struct request *req)
 259 {
 260         struct blkfront_info *info = req->rq_disk->private_data;
 261         unsigned long buffer_mfn;
 262         struct blkif_request *ring_req;
 263         unsigned long id;
 264         unsigned int fsect, lsect;
 265         int i, ref;
 266         grant_ref_t gref_head;
 267         struct scatterlist *sg;
 268
 269         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
 270                 return 1;
 271
 272         if (gnttab_alloc_grant_references(
 273                 BLKIF_MAX_SEGMENTS_PER_REQUEST, &gref_head) < 0) {
 274                 gnttab_request_free_callback(
 275                         &info->callback,
 276                         blkif_restart_queue_callback,
 277                         info,
 278                         BLKIF_MAX_SEGMENTS_PER_REQUEST);
 279                 return 1;
 280         }
 281
 282         /* Fill out a communications ring structure. */
 283         ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
 284         id = get_id_from_freelist(info);
 285         info->shadow[id].request = req;
 286
 287         ring_req->id = id;
 288         ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 289         ring_req->handle = info->handle;
 290
 291         ring_req->operation = rq_data_dir(req) ?
 292                 BLKIF_OP_WRITE : BLKIF_OP_READ;
 293
 294         if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
 295                 /*
 296                  * Ideally we can do an unordered flush-to-disk. In case the
 297                  * backend onlysupports barriers, use that. A barrier request
 298                  * a superset of FUA, so we can implement it the same
 299                  * way.  (It's also a FLUSH+FUA, since it is
 300                  * guaranteed ordered WRT previous writes.)
 301                  */
 302                 ring_req->operation = info->flush_op;
 303         }
 304
 305         ring_req->nr_segments = blk_rq_map_sg(req->q, req, info->sg);
 306         BUG_ON(ring_req->nr_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
 307
 308         for_each_sg(info->sg, sg, ring_req->nr_segments, i) {
 309                 buffer_mfn = pfn_to_mfn(page_to_pfn(sg_page(sg)));
 310                 fsect = sg->offset >> 9;
 311                 lsect = fsect + (sg->length >> 9) - 1;
 312                 /* install a grant reference. */
 313                 ref = gnttab_claim_grant_reference(&gref_head);
 314                 BUG_ON(ref == -ENOSPC);
 315
 316                 gnttab_grant_foreign_access_ref(
 317                                 ref,
 318                                 info->xbdev->otherend_id,
 319                                 buffer_mfn,
 320                                 rq_data_dir(req) );
 321
 322                 info->shadow[id].frame[i] = mfn_to_pfn(buffer_mfn);
 323                 ring_req->u.rw.seg[i] =
 324                                 (struct blkif_request_segment) {
 325                                         .gref       = ref,
 326                                         .first_sect = fsect,
 327                                         .last_sect  = lsect };
 328         }
 329
 330         info->ring.req_prod_pvt++;
 331
 332         /* Keep a private copy so we can reissue requests when recovering. */
 333         info->shadow[id].req = *ring_req;
 334
 335         gnttab_free_grant_references(gref_head);
 336
 337         return 0;
 338 }
 339
 340
 341 static inline void flush_requests(struct blkfront_info *info)
 342 {
 343         int notify;
 344
 345         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
 346
 347         if (notify)
 348                 notify_remote_via_irq(info->irq);
 349 }
 350
 351 /*
 352  * do_blkif_request
 353  *  read a block; request is in a request queue
 354  */
 355 static void do_blkif_request(struct request_queue *rq)
 356 {
 357         struct blkfront_info *info = NULL;
 358         struct request *req;
 359         int queued;
 360
 361         pr_debug("Entered do_blkif_request\n");
 362
 363         queued = 0;
 364
 365         while ((req = blk_peek_request(rq)) != NULL) {
 366                 info = req->rq_disk->private_data;
 367
 368                 if (RING_FULL(&info->ring))
 369                         goto wait;
 370
 371                 blk_start_request(req);
 372
 373                 if (req->cmd_type != REQ_TYPE_FS) {
 374                         __blk_end_request_all(req, -EIO);
 375                         continue;
 376                 }
 377
 378                 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
 379                          "(%u/%u) buffer:%p [%s]\n",
 380                          req, req->cmd, (unsigned long)blk_rq_pos(req),
 381                          blk_rq_cur_sectors(req), blk_rq_sectors(req),
 382                          req->buffer, rq_data_dir(req) ? "write" : "read");
 383
 384                 if (blkif_queue_request(req)) {
 385                         blk_requeue_request(rq, req);
 386 wait:
 387                         /* Avoid pointless unplugs. */
 388                         blk_stop_queue(rq);
 389                         break;
 390                 }
 391
 392                 queued++;
 393         }
 394
 395         if (queued != 0)
 396                 flush_requests(info);
 397 }
 398
 399 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size)
 400 {
 401         struct request_queue *rq;
 402
 403         rq = blk_init_queue(do_blkif_request, &blkif_io_lock);
 404         if (rq == NULL)
 405                 return -1;
 406
 407         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
 408
 409         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 410         blk_queue_logical_block_size(rq, sector_size);
 411         blk_queue_max_hw_sectors(rq, 512);
 412
 413         /* Each segment in a request is up to an aligned page in size. */
 414         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 415         blk_queue_max_segment_size(rq, PAGE_SIZE);
 416
 417         /* Ensure a merged request will fit in a single I/O ring slot. */
 418         blk_queue_max_segments(rq, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 419
 420         /* Make sure buffer addresses are sector-aligned. */
 421         blk_queue_dma_alignment(rq, 511);
 422
 423         /* Make sure we don't use bounce buffers. */
 424         blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
 425
 426         gd->queue = rq;
 427
 428         return 0;
 429 }
 430
 431
 432 static void xlvbd_flush(struct blkfront_info *info)
 433 {
 434         blk_queue_flush(info->rq, info->feature_flush);
 435         printk(KERN_INFO "blkfront: %s: %s: %s\n",
 436                info->gd->disk_name,
 437                info->flush_op == BLKIF_OP_WRITE_BARRIER ?
 438                 "barrier" : (info->flush_op == BLKIF_OP_FLUSH_DISKCACHE ?
 439                 "flush diskcache" : "barrier or flush"),
 440                info->feature_flush ? "enabled" : "disabled");
 441 }
 442
 443 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
 444 {
 445         int major;
 446         major = BLKIF_MAJOR(vdevice);
 447         *minor = BLKIF_MINOR(vdevice);
 448         switch (major) {
 449                 case XEN_IDE0_MAJOR:
 450                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
 451                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
 452                                 EMULATED_HD_DISK_MINOR_OFFSET;
 453                         break;
 454                 case XEN_IDE1_MAJOR:
 455                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
 456                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
 457                                 EMULATED_HD_DISK_MINOR_OFFSET;
 458                         break;
 459                 case XEN_SCSI_DISK0_MAJOR:
 460                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
 461                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
 462                         break;
 463                 case XEN_SCSI_DISK1_MAJOR:
 464                 case XEN_SCSI_DISK2_MAJOR:
 465                 case XEN_SCSI_DISK3_MAJOR:
 466                 case XEN_SCSI_DISK4_MAJOR:
 467                 case XEN_SCSI_DISK5_MAJOR:
 468                 case XEN_SCSI_DISK6_MAJOR:
 469                 case XEN_SCSI_DISK7_MAJOR:
 470                         *offset = (*minor / PARTS_PER_DISK) +
 471                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
 472                                 EMULATED_SD_DISK_NAME_OFFSET;
 473                         *minor = *minor +
 474                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
 475                                 EMULATED_SD_DISK_MINOR_OFFSET;
 476                         break;
 477                 case XEN_SCSI_DISK8_MAJOR:
 478                 case XEN_SCSI_DISK9_MAJOR:
 479                 case XEN_SCSI_DISK10_MAJOR:
 480                 case XEN_SCSI_DISK11_MAJOR:
 481                 case XEN_SCSI_DISK12_MAJOR:
 482                 case XEN_SCSI_DISK13_MAJOR:
 483                 case XEN_SCSI_DISK14_MAJOR:
 484                 case XEN_SCSI_DISK15_MAJOR:
 485                         *offset = (*minor / PARTS_PER_DISK) +
 486                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
 487                                 EMULATED_SD_DISK_NAME_OFFSET;
 488                         *minor = *minor +
 489                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
 490                                 EMULATED_SD_DISK_MINOR_OFFSET;
 491                         break;
 492                 case XENVBD_MAJOR:
 493                         *offset = *minor / PARTS_PER_DISK;
 494                         break;
 495                 default:
 496                         printk(KERN_WARNING "blkfront: your disk configuration is "
 497                                         "incorrect, please use an xvd device instead\n");
 498                         return -ENODEV;
 499         }
 500         return 0;
 501 }
 502
 503 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 504                                struct blkfront_info *info,
 505                                u16 vdisk_info, u16 sector_size)
 506 {
 507         struct gendisk *gd;
 508         int nr_minors = 1;
 509         int err;
 510         unsigned int offset;
 511         int minor;
 512         int nr_parts;
 513
 514         BUG_ON(info->gd != NULL);
 515         BUG_ON(info->rq != NULL);
 516
 517         if ((info->vdevice>>EXT_SHIFT) > 1) {
 518                 /* this is above the extended range; something is wrong */
 519                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
 520                 return -ENODEV;
 521         }
 522
 523         if (!VDEV_IS_EXTENDED(info->vdevice)) {
 524                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
 525                 if (err)
 526                         return err;
 527                 nr_parts = PARTS_PER_DISK;
 528         } else {
 529                 minor = BLKIF_MINOR_EXT(info->vdevice);
 530                 nr_parts = PARTS_PER_EXT_DISK;
 531                 offset = minor / nr_parts;
 532                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
 533                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
 534                                         "emulated IDE disks,\n\t choose an xvd device name"
 535                                         "from xvde on\n", info->vdevice);
 536         }
 537         err = -ENODEV;
 538
 539         if ((minor % nr_parts) == 0)
 540                 nr_minors = nr_parts;
 541
 542         err = xlbd_reserve_minors(minor, nr_minors);
 543         if (err)
 544                 goto out;
 545         err = -ENODEV;
 546
 547         gd = alloc_disk(nr_minors);
 548         if (gd == NULL)
 549                 goto release;
 550
 551         if (nr_minors > 1) {
 552                 if (offset < 26)
 553                         sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);
 554                 else
 555                         sprintf(gd->disk_name, "%s%c%c", DEV_NAME,
 556                                 'a' + ((offset / 26)-1), 'a' + (offset % 26));
 557         } else {
 558                 if (offset < 26)
 559                         sprintf(gd->disk_name, "%s%c%d", DEV_NAME,
 560                                 'a' + offset,
 561                                 minor & (nr_parts - 1));
 562                 else
 563                         sprintf(gd->disk_name, "%s%c%c%d", DEV_NAME,
 564                                 'a' + ((offset / 26) - 1),
 565                                 'a' + (offset % 26),
 566                                 minor & (nr_parts - 1));
 567         }
 568
 569         gd->major = XENVBD_MAJOR;
 570         gd->first_minor = minor;
 571         gd->fops = &xlvbd_block_fops;
 572         gd->private_data = info;
 573         gd->driverfs_dev = &(info->xbdev->dev);
 574         set_capacity(gd, capacity);
 575
 576         if (xlvbd_init_blk_queue(gd, sector_size)) {
 577                 del_gendisk(gd);
 578                 goto release;
 579         }
 580
 581         info->rq = gd->queue;
 582         info->gd = gd;
 583
 584         xlvbd_flush(info);
 585
 586         if (vdisk_info & VDISK_READONLY)
 587                 set_disk_ro(gd, 1);
 588
 589         if (vdisk_info & VDISK_REMOVABLE)
 590                 gd->flags |= GENHD_FL_REMOVABLE;
 591
 592         if (vdisk_info & VDISK_CDROM)
 593                 gd->flags |= GENHD_FL_CD;
 594
 595         return 0;
 596
 597  release:
 598         xlbd_release_minors(minor, nr_minors);
 599  out:
 600         return err;
 601 }
 602
 603 static void xlvbd_release_gendisk(struct blkfront_info *info)
 604 {
 605         unsigned int minor, nr_minors;
 606         unsigned long flags;
 607
 608         if (info->rq == NULL)
 609                 return;
 610
 611         spin_lock_irqsave(&blkif_io_lock, flags);
 612
 613         /* No more blkif_request(). */
 614         blk_stop_queue(info->rq);
 615
 616         /* No more gnttab callback work. */
 617         gnttab_cancel_free_callback(&info->callback);
 618         spin_unlock_irqrestore(&blkif_io_lock, flags);
 619
 620         /* Flush gnttab callback work. Must be done with no locks held. */
 621         flush_work_sync(&info->work);
 622
 623         del_gendisk(info->gd);
 624
 625         minor = info->gd->first_minor;
 626         nr_minors = info->gd->minors;
 627         xlbd_release_minors(minor, nr_minors);
 628
 629         blk_cleanup_queue(info->rq);
 630         info->rq = NULL;
 631
 632         put_disk(info->gd);
 633         info->gd = NULL;
 634 }
 635
 636 static void kick_pending_request_queues(struct blkfront_info *info)
 637 {
 638         if (!RING_FULL(&info->ring)) {
 639                 /* Re-enable calldowns. */
 640                 blk_start_queue(info->rq);
 641                 /* Kick things off immediately. */
 642                 do_blkif_request(info->rq);
 643         }
 644 }
 645
 646 static void blkif_restart_queue(struct work_struct *work)
 647 {
 648         struct blkfront_info *info = container_of(work, struct blkfront_info, work);
 649
 650         spin_lock_irq(&blkif_io_lock);
 651         if (info->connected == BLKIF_STATE_CONNECTED)
 652                 kick_pending_request_queues(info);
 653         spin_unlock_irq(&blkif_io_lock);
 654 }
 655
 656 static void blkif_free(struct blkfront_info *info, int suspend)
 657 {
 658         /* Prevent new requests being issued until we fix things up. */
 659         spin_lock_irq(&blkif_io_lock);
 660         info->connected = suspend ?
 661                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
 662         /* No more blkif_request(). */
 663         if (info->rq)
 664                 blk_stop_queue(info->rq);
 665         /* No more gnttab callback work. */
 666         gnttab_cancel_free_callback(&info->callback);
 667         spin_unlock_irq(&blkif_io_lock);
 668
 669         /* Flush gnttab callback work. Must be done with no locks held. */
 670         flush_work_sync(&info->work);
 671
 672         /* Free resources associated with old device channel. */
 673         if (info->ring_ref != GRANT_INVALID_REF) {
 674                 gnttab_end_foreign_access(info->ring_ref, 0,
 675                                           (unsigned long)info->ring.sring);
 676                 info->ring_ref = GRANT_INVALID_REF;
 677                 info->ring.sring = NULL;
 678         }
 679         if (info->irq)
 680                 unbind_from_irqhandler(info->irq, info);
 681         info->evtchn = info->irq = 0;
 682
 683 }
 684
 685 static void blkif_completion(struct blk_shadow *s)
 686 {
 687         int i;
 688         for (i = 0; i < s->req.nr_segments; i++)
 689                 gnttab_end_foreign_access(s->req.u.rw.seg[i].gref, 0, 0UL);
 690 }
 691
 692 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
 693 {
 694         struct request *req;
 695         struct blkif_response *bret;
 696         RING_IDX i, rp;
 697         unsigned long flags;
 698         struct blkfront_info *info = (struct blkfront_info *)dev_id;
 699         int error;
 700
 701         spin_lock_irqsave(&blkif_io_lock, flags);
 702
 703         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
 704                 spin_unlock_irqrestore(&blkif_io_lock, flags);
 705                 return IRQ_HANDLED;
 706         }
 707
 708  again:
 709         rp = info->ring.sring->rsp_prod;
 710         rmb(); /* Ensure we see queued responses up to 'rp'. */
 711
 712         for (i = info->ring.rsp_cons; i != rp; i++) {
 713                 unsigned long id;
 714
 715                 bret = RING_GET_RESPONSE(&info->ring, i);
 716                 id   = bret->id;
 717                 req  = info->shadow[id].request;
 718
 719                 blkif_completion(&info->shadow[id]);
 720
 721                 add_id_to_freelist(info, id);
 722
 723                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
 724                 switch (bret->operation) {
 725                 case BLKIF_OP_FLUSH_DISKCACHE:
 726                 case BLKIF_OP_WRITE_BARRIER:
 727                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
 728                                 printk(KERN_WARNING "blkfront: %s: write %s op failed\n",
 729                                        info->flush_op == BLKIF_OP_WRITE_BARRIER ?
 730                                        "barrier" :  "flush disk cache",
 731                                        info->gd->disk_name);
 732                                 error = -EOPNOTSUPP;
 733                         }
 734                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
 735                                      info->shadow[id].req.nr_segments == 0)) {
 736                                 printk(KERN_WARNING "blkfront: %s: empty write %s op failed\n",
 737                                        info->flush_op == BLKIF_OP_WRITE_BARRIER ?
 738                                        "barrier" :  "flush disk cache",
 739                                        info->gd->disk_name);
 740                                 error = -EOPNOTSUPP;
 741                         }
 742                         if (unlikely(error)) {
 743                                 if (error == -EOPNOTSUPP)
 744                                         error = 0;
 745                                 info->feature_flush = 0;
 746                                 info->flush_op = 0;
 747                                 xlvbd_flush(info);
 748                         }
 749                         /* fall through */
 750                 case BLKIF_OP_READ:
 751                 case BLKIF_OP_WRITE:
 752                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
 753                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
 754                                         "request: %x\n", bret->status);
 755
 756                         __blk_end_request_all(req, error);
 757                         break;
 758                 default:
 759                         BUG();
 760                 }
 761         }
 762
 763         info->ring.rsp_cons = i;
 764
 765         if (i != info->ring.req_prod_pvt) {
 766                 int more_to_do;
 767                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
 768                 if (more_to_do)
 769                         goto again;
 770         } else
 771                 info->ring.sring->rsp_event = i + 1;
 772
 773         kick_pending_request_queues(info);
 774
 775         spin_unlock_irqrestore(&blkif_io_lock, flags);
 776
 777         return IRQ_HANDLED;
 778 }
 779
 780
 781 static int setup_blkring(struct xenbus_device *dev,
 782                          struct blkfront_info *info)
 783 {
 784         struct blkif_sring *sring;
 785         int err;
 786
 787         info->ring_ref = GRANT_INVALID_REF;
 788
 789         sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
 790         if (!sring) {
 791                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
 792                 return -ENOMEM;
 793         }
 794         SHARED_RING_INIT(sring);
 795         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 796
 797         sg_init_table(info->sg, BLKIF_MAX_SEGMENTS_PER_REQUEST);
 798
 799         err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
 800         if (err < 0) {
 801                 free_page((unsigned long)sring);
 802                 info->ring.sring = NULL;
 803                 goto fail;
 804         }
 805         info->ring_ref = err;
 806
 807         err = xenbus_alloc_evtchn(dev, &info->evtchn);
 808         if (err)
 809                 goto fail;
 810
 811         err = bind_evtchn_to_irqhandler(info->evtchn,
 812                                         blkif_interrupt,
 813                                         IRQF_SAMPLE_RANDOM, "blkif", info);
 814         if (err <= 0) {
 815                 xenbus_dev_fatal(dev, err,
 816                                  "bind_evtchn_to_irqhandler failed");
 817                 goto fail;
 818         }
 819         info->irq = err;
 820
 821         return 0;
 822 fail:
 823         blkif_free(info, 0);
 824         return err;
 825 }
 826
 827
 828 /* Common code used when first setting up, and when resuming. */
 829 static int talk_to_blkback(struct xenbus_device *dev,
 830                            struct blkfront_info *info)
 831 {
 832         const char *message = NULL;
 833         struct xenbus_transaction xbt;
 834         int err;
 835
 836         /* Create shared ring, alloc event channel. */
 837         err = setup_blkring(dev, info);
 838         if (err)
 839                 goto out;
 840
 841 again:
 842         err = xenbus_transaction_start(&xbt);
 843         if (err) {
 844                 xenbus_dev_fatal(dev, err, "starting transaction");
 845                 goto destroy_blkring;
 846         }
 847
 848         err = xenbus_printf(xbt, dev->nodename,
 849                             "ring-ref", "%u", info->ring_ref);
 850         if (err) {
 851                 message = "writing ring-ref";
 852                 goto abort_transaction;
 853         }
 854         err = xenbus_printf(xbt, dev->nodename,
 855                             "event-channel", "%u", info->evtchn);
 856         if (err) {
 857                 message = "writing event-channel";
 858                 goto abort_transaction;
 859         }
 860         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
 861                             XEN_IO_PROTO_ABI_NATIVE);
 862         if (err) {
 863                 message = "writing protocol";
 864                 goto abort_transaction;
 865         }
 866
 867         err = xenbus_transaction_end(xbt, 0);
 868         if (err) {
 869                 if (err == -EAGAIN)
 870                         goto again;
 871                 xenbus_dev_fatal(dev, err, "completing transaction");
 872                 goto destroy_blkring;
 873         }
 874
 875         xenbus_switch_state(dev, XenbusStateInitialised);
 876
 877         return 0;
 878
 879  abort_transaction:
 880         xenbus_transaction_end(xbt, 1);
 881         if (message)
 882                 xenbus_dev_fatal(dev, err, "%s", message);
 883  destroy_blkring:
 884         blkif_free(info, 0);
 885  out:
 886         return err;
 887 }
 888
 889 /**
 890  * Entry point to this code when a new device is created.  Allocate the basic
 891  * structures and the ring buffer for communication with the backend, and
 892  * inform the backend of the appropriate details for those.  Switch to
 893  * Initialised state.
 894  */
 895 static int blkfront_probe(struct xenbus_device *dev,
 896                           const struct xenbus_device_id *id)
 897 {
 898         int err, vdevice, i;
 899         struct blkfront_info *info;
 900
 901         /* FIXME: Use dynamic device id if this is not set. */
 902         err = xenbus_scanf(XBT_NIL, dev->nodename,
 903                            "virtual-device", "%i", &vdevice);
 904         if (err != 1) {
 905                 /* go looking in the extended area instead */
 906                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
 907                                    "%i", &vdevice);
 908                 if (err != 1) {
 909                         xenbus_dev_fatal(dev, err, "reading virtual-device");
 910                         return err;
 911                 }
 912         }
 913
 914         if (xen_hvm_domain()) {
 915                 char *type;
 916                 int len;
 917                 /* no unplug has been done: do not hook devices != xen vbds */
 918                 if (xen_platform_pci_unplug & XEN_UNPLUG_UNNECESSARY) {
 919                         int major;
 920
 921                         if (!VDEV_IS_EXTENDED(vdevice))
 922                                 major = BLKIF_MAJOR(vdevice);
 923                         else
 924                                 major = XENVBD_MAJOR;
 925
 926                         if (major != XENVBD_MAJOR) {
 927                                 printk(KERN_INFO
 928                                                 "%s: HVM does not support vbd %d as xen block device\n",
 929                                                 __FUNCTION__, vdevice);
 930                                 return -ENODEV;
 931                         }
 932                 }
 933                 /* do not create a PV cdrom device if we are an HVM guest */
 934                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
 935                 if (IS_ERR(type))
 936                         return -ENODEV;
 937                 if (strncmp(type, "cdrom", 5) == 0) {
 938                         kfree(type);
 939                         return -ENODEV;
 940                 }
 941                 kfree(type);
 942         }
 943         info = kzalloc(sizeof(*info), GFP_KERNEL);
 944         if (!info) {
 945                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
 946                 return -ENOMEM;
 947         }
 948
 949         mutex_init(&info->mutex);
 950         info->xbdev = dev;
 951         info->vdevice = vdevice;
 952         info->connected = BLKIF_STATE_DISCONNECTED;
 953         INIT_WORK(&info->work, blkif_restart_queue);
 954
 955         for (i = 0; i < BLK_RING_SIZE; i++)
 956                 info->shadow[i].req.id = i+1;
 957         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
 958
 959         /* Front end dir is a number, which is used as the id. */
 960         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
 961         dev_set_drvdata(&dev->dev, info);
 962
 963         err = talk_to_blkback(dev, info);
 964         if (err) {
 965                 kfree(info);
 966                 dev_set_drvdata(&dev->dev, NULL);
 967                 return err;
 968         }
 969
 970         return 0;
 971 }
 972
 973
 974 static int blkif_recover(struct blkfront_info *info)
 975 {
 976         int i;
 977         struct blkif_request *req;
 978         struct blk_shadow *copy;
 979         int j;
 980
 981         /* Stage 1: Make a safe copy of the shadow state. */
 982         copy = kmalloc(sizeof(info->shadow),
 983                        GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
 984         if (!copy)
 985                 return -ENOMEM;
 986         memcpy(copy, info->shadow, sizeof(info->shadow));
 987
 988         /* Stage 2: Set up free list. */
 989         memset(&info->shadow, 0, sizeof(info->shadow));
 990         for (i = 0; i < BLK_RING_SIZE; i++)
 991                 info->shadow[i].req.id = i+1;
 992         info->shadow_free = info->ring.req_prod_pvt;
 993         info->shadow[BLK_RING_SIZE-1].req.id = 0x0fffffff;
 994
 995         /* Stage 3: Find pending requests and requeue them. */
 996         for (i = 0; i < BLK_RING_SIZE; i++) {
 997                 /* Not in use? */
 998                 if (!copy[i].request)
 999                         continue;
1000
1001                 /* Grab a request slot and copy shadow state into it. */
1002                 req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
1003                 *req = copy[i].req;
1004
1005                 /* We get a new request id, and must reset the shadow state. */
1006                 req->id = get_id_from_freelist(info);
1007                 memcpy(&info->shadow[req->id], &copy[i], sizeof(copy[i]));
1008
1009                 /* Rewrite any grant references invalidated by susp/resume. */
1010                 for (j = 0; j < req->nr_segments; j++)
1011                         gnttab_grant_foreign_access_ref(
1012                                 req->u.rw.seg[j].gref,
1013                                 info->xbdev->otherend_id,
1014                                 pfn_to_mfn(info->shadow[req->id].frame[j]),
1015                                 rq_data_dir(info->shadow[req->id].request));
1016                 info->shadow[req->id].req = *req;
1017
1018                 info->ring.req_prod_pvt++;
1019         }
1020
1021         kfree(copy);
1022
1023         xenbus_switch_state(info->xbdev, XenbusStateConnected);
1024
1025         spin_lock_irq(&blkif_io_lock);
1026
1027         /* Now safe for us to use the shared ring */
1028         info->connected = BLKIF_STATE_CONNECTED;
1029
1030         /* Send off requeued requests */
1031         flush_requests(info);
1032
1033         /* Kick any other new requests queued since we resumed */
1034         kick_pending_request_queues(info);
1035
1036         spin_unlock_irq(&blkif_io_lock);
1037
1038         return 0;
1039 }
1040
1041 /**
1042  * We are reconnecting to the backend, due to a suspend/resume, or a backend
1043  * driver restart.  We tear down our blkif structure and recreate it, but
1044  * leave the device-layer structures intact so that this is transparent to the
1045  * rest of the kernel.
1046  */
1047 static int blkfront_resume(struct xenbus_device *dev)
1048 {
1049         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1050         int err;
1051
1052         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1053
1054         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1055
1056         err = talk_to_blkback(dev, info);
1057         if (info->connected == BLKIF_STATE_SUSPENDED && !err)
1058                 err = blkif_recover(info);
1059
1060         return err;
1061 }
1062
1063 static void
1064 blkfront_closing(struct blkfront_info *info)
1065 {
1066         struct xenbus_device *xbdev = info->xbdev;
1067         struct block_device *bdev = NULL;
1068
1069         mutex_lock(&info->mutex);
1070
1071         if (xbdev->state == XenbusStateClosing) {
1072                 mutex_unlock(&info->mutex);
1073                 return;
1074         }
1075
1076         if (info->gd)
1077                 bdev = bdget_disk(info->gd, 0);
1078
1079         mutex_unlock(&info->mutex);
1080
1081         if (!bdev) {
1082                 xenbus_frontend_closed(xbdev);
1083                 return;
1084         }
1085
1086         mutex_lock(&bdev->bd_mutex);
1087
1088         if (bdev->bd_openers) {
1089                 xenbus_dev_error(xbdev, -EBUSY,
1090                                  "Device in use; refusing to close");
1091                 xenbus_switch_state(xbdev, XenbusStateClosing);
1092         } else {
1093                 xlvbd_release_gendisk(info);
1094                 xenbus_frontend_closed(xbdev);
1095         }
1096
1097         mutex_unlock(&bdev->bd_mutex);
1098         bdput(bdev);
1099 }
1100
1101 /*
1102  * Invoked when the backend is finally 'ready' (and has told produced
1103  * the details about the physical device - #sectors, size, etc).
1104  */
1105 static void blkfront_connect(struct blkfront_info *info)
1106 {
1107         unsigned long long sectors;
1108         unsigned long sector_size;
1109         unsigned int binfo;
1110         int err;
1111         int barrier, flush;
1112
1113         switch (info->connected) {
1114         case BLKIF_STATE_CONNECTED:
1115                 /*
1116                  * Potentially, the back-end may be signalling
1117                  * a capacity change; update the capacity.
1118                  */
1119                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1120                                    "sectors", "%Lu", &sectors);
1121                 if (XENBUS_EXIST_ERR(err))
1122                         return;
1123                 printk(KERN_INFO "Setting capacity to %Lu\n",
1124                        sectors);
1125                 set_capacity(info->gd, sectors);
1126                 revalidate_disk(info->gd);
1127
1128                 /* fall through */
1129         case BLKIF_STATE_SUSPENDED:
1130                 return;
1131
1132         default:
1133                 break;
1134         }
1135
1136         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1137                 __func__, info->xbdev->otherend);
1138
1139         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1140                             "sectors", "%llu", &sectors,
1141                             "info", "%u", &binfo,
1142                             "sector-size", "%lu", &sector_size,
1143                             NULL);
1144         if (err) {
1145                 xenbus_dev_fatal(info->xbdev, err,
1146                                  "reading backend fields at %s",
1147                                  info->xbdev->otherend);
1148                 return;
1149         }
1150
1151         info->feature_flush = 0;
1152         info->flush_op = 0;
1153
1154         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1155                             "feature-barrier", "%d", &barrier,
1156                             NULL);
1157
1158         /*
1159          * If there's no "feature-barrier" defined, then it means
1160          * we're dealing with a very old backend which writes
1161          * synchronously; nothing to do.
1162          *
1163          * If there are barriers, then we use flush.
1164          */
1165         if (!err && barrier) {
1166                 info->feature_flush = REQ_FLUSH | REQ_FUA;
1167                 info->flush_op = BLKIF_OP_WRITE_BARRIER;
1168         }
1169         /*
1170          * And if there is "feature-flush-cache" use that above
1171          * barriers.
1172          */
1173         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1174                             "feature-flush-cache", "%d", &flush,
1175                             NULL);
1176
1177         if (!err && flush) {
1178                 info->feature_flush = REQ_FLUSH;
1179                 info->flush_op = BLKIF_OP_FLUSH_DISKCACHE;
1180         }
1181
1182         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size);
1183         if (err) {
1184                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1185                                  info->xbdev->otherend);
1186                 return;
1187         }
1188
1189         xenbus_switch_state(info->xbdev, XenbusStateConnected);
1190
1191         /* Kick pending requests. */
1192         spin_lock_irq(&blkif_io_lock);
1193         info->connected = BLKIF_STATE_CONNECTED;
1194         kick_pending_request_queues(info);
1195         spin_unlock_irq(&blkif_io_lock);
1196
1197         add_disk(info->gd);
1198
1199         info->is_ready = 1;
1200 }
1201
1202 /**
1203  * Callback received when the backend's state changes.
1204  */
1205 static void blkback_changed(struct xenbus_device *dev,
1206                             enum xenbus_state backend_state)
1207 {
1208         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1209
1210         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1211
1212         switch (backend_state) {
1213         case XenbusStateInitialising:
1214         case XenbusStateInitWait:
1215         case XenbusStateInitialised:
1216         case XenbusStateReconfiguring:
1217         case XenbusStateReconfigured:
1218         case XenbusStateUnknown:
1219         case XenbusStateClosed:
1220                 break;
1221
1222         case XenbusStateConnected:
1223                 blkfront_connect(info);
1224                 break;
1225
1226         case XenbusStateClosing:
1227                 blkfront_closing(info);
1228                 break;
1229         }
1230 }
1231
1232 static int blkfront_remove(struct xenbus_device *xbdev)
1233 {
1234         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1235         struct block_device *bdev = NULL;
1236         struct gendisk *disk;
1237
1238         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1239
1240         blkif_free(info, 0);
1241
1242         mutex_lock(&info->mutex);
1243
1244         disk = info->gd;
1245         if (disk)
1246                 bdev = bdget_disk(disk, 0);
1247
1248         info->xbdev = NULL;
1249         mutex_unlock(&info->mutex);
1250
1251         if (!bdev) {
1252                 kfree(info);
1253                 return 0;
1254         }
1255
1256         /*
1257          * The xbdev was removed before we reached the Closed
1258          * state. See if it's safe to remove the disk. If the bdev
1259          * isn't closed yet, we let release take care of it.
1260          */
1261
1262         mutex_lock(&bdev->bd_mutex);
1263         info = disk->private_data;
1264
1265         dev_warn(disk_to_dev(disk),
1266                  "%s was hot-unplugged, %d stale handles\n",
1267                  xbdev->nodename, bdev->bd_openers);
1268
1269         if (info && !bdev->bd_openers) {
1270                 xlvbd_release_gendisk(info);
1271                 disk->private_data = NULL;
1272                 kfree(info);
1273         }
1274
1275         mutex_unlock(&bdev->bd_mutex);
1276         bdput(bdev);
1277
1278         return 0;
1279 }
1280
1281 static int blkfront_is_ready(struct xenbus_device *dev)
1282 {
1283         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1284
1285         return info->is_ready && info->xbdev;
1286 }
1287
1288 static int blkif_open(struct block_device *bdev, fmode_t mode)
1289 {
1290         struct gendisk *disk = bdev->bd_disk;
1291         struct blkfront_info *info;
1292         int err = 0;
1293
1294         mutex_lock(&blkfront_mutex);
1295
1296         info = disk->private_data;
1297         if (!info) {
1298                 /* xbdev gone */
1299                 err = -ERESTARTSYS;
1300                 goto out;
1301         }
1302
1303         mutex_lock(&info->mutex);
1304
1305         if (!info->gd)
1306                 /* xbdev is closed */
1307                 err = -ERESTARTSYS;
1308
1309         mutex_unlock(&info->mutex);
1310
1311 out:
1312         mutex_unlock(&blkfront_mutex);
1313         return err;
1314 }
1315
1316 static int blkif_release(struct gendisk *disk, fmode_t mode)
1317 {
1318         struct blkfront_info *info = disk->private_data;
1319         struct block_device *bdev;
1320         struct xenbus_device *xbdev;
1321
1322         mutex_lock(&blkfront_mutex);
1323
1324         bdev = bdget_disk(disk, 0);
1325         bdput(bdev);
1326
1327         if (bdev->bd_openers)
1328                 goto out;
1329
1330         /*
1331          * Check if we have been instructed to close. We will have
1332          * deferred this request, because the bdev was still open.
1333          */
1334
1335         mutex_lock(&info->mutex);
1336         xbdev = info->xbdev;
1337
1338         if (xbdev && xbdev->state == XenbusStateClosing) {
1339                 /* pending switch to state closed */
1340                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1341                 xlvbd_release_gendisk(info);
1342                 xenbus_frontend_closed(info->xbdev);
1343         }
1344
1345         mutex_unlock(&info->mutex);
1346
1347         if (!xbdev) {
1348                 /* sudden device removal */
1349                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
1350                 xlvbd_release_gendisk(info);
1351                 disk->private_data = NULL;
1352                 kfree(info);
1353         }
1354
1355 out:
1356         mutex_unlock(&blkfront_mutex);
1357         return 0;
1358 }
1359
1360 static const struct block_device_operations xlvbd_block_fops =
1361 {
1362         .owner = THIS_MODULE,
1363         .open = blkif_open,
1364         .release = blkif_release,
1365         .getgeo = blkif_getgeo,
1366         .ioctl = blkif_ioctl,
1367 };
1368
1369
1370 static const struct xenbus_device_id blkfront_ids[] = {
1371         { "vbd" },
1372         { "" }
1373 };
1374
1375 static struct xenbus_driver blkfront = {
1376         .name = "vbd",
1377         .owner = THIS_MODULE,
1378         .ids = blkfront_ids,
1379         .probe = blkfront_probe,
1380         .remove = blkfront_remove,
1381         .resume = blkfront_resume,
1382         .otherend_changed = blkback_changed,
1383         .is_ready = blkfront_is_ready,
1384 };
1385
1386 static int __init xlblk_init(void)
1387 {
1388         if (!xen_domain())
1389                 return -ENODEV;
1390
1391         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
1392                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
1393                        XENVBD_MAJOR, DEV_NAME);
1394                 return -ENODEV;
1395         }
1396
1397         return xenbus_register_frontend(&blkfront);
1398 }
1399 module_init(xlblk_init);
1400
1401
1402 static void __exit xlblk_exit(void)
1403 {
1404         return xenbus_unregister_driver(&blkfront);
1405 }
1406 module_exit(xlblk_exit);
1407
1408 MODULE_DESCRIPTION("Xen virtual block device frontend");
1409 MODULE_LICENSE("GPL");
1410 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
1411 MODULE_ALIAS("xen:vbd");
1412 MODULE_ALIAS("xenblk");