kernel/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 #include <linux/bitmap.h>
  47 #include <linux/list.h>
  48
  49 #include <xen/xen.h>
  50 #include <xen/xenbus.h>
  51 #include <xen/grant_table.h>
  52 #include <xen/events.h>
  53 #include <xen/page.h>
  54 #include <xen/platform_pci.h>
  55
  56 #include <xen/interface/grant_table.h>
  57 #include <xen/interface/io/blkif.h>
  58 #include <xen/interface/io/protocols.h>
  59
  60 #include <asm/xen/hypervisor.h>
  61
  62 enum blkif_state {
  63         BLKIF_STATE_DISCONNECTED,
  64         BLKIF_STATE_CONNECTED,
  65         BLKIF_STATE_SUSPENDED,
  66 };
  67
  68 struct grant {
  69         grant_ref_t gref;
  70         unsigned long pfn;
  71         struct list_head node;
  72 };
  73
  74 struct blk_shadow {
  75         struct blkif_request req;
  76         struct request *request;
  77         struct grant **grants_used;
  78         struct grant **indirect_grants;
  79         struct scatterlist *sg;
  80 };
  81
  82 struct split_bio {
  83         struct bio *bio;
  84         atomic_t pending;
  85         int err;
  86 };
  87
  88 static DEFINE_MUTEX(blkfront_mutex);
  89 static const struct block_device_operations xlvbd_block_fops;
  90
  91 /*
  92  * Maximum number of segments in indirect requests, the actual value used by
  93  * the frontend driver is the minimum of this value and the value provided
  94  * by the backend driver.
  95  */
  96
  97 static unsigned int xen_blkif_max_segments = 32;
  98 module_param_named(max, xen_blkif_max_segments, int, S_IRUGO);
  99 MODULE_PARM_DESC(max, "Maximum amount of segments in indirect requests (default is 32)");
 100
 101 #define BLK_RING_SIZE __CONST_RING_SIZE(blkif, PAGE_SIZE)
 102
 103 /*
 104  * We have one of these per vbd, whether ide, scsi or 'other'.  They
 105  * hang in private_data off the gendisk structure. We may end up
 106  * putting all kinds of interesting stuff here :-)
 107  */
 108 struct blkfront_info
 109 {
 110         spinlock_t io_lock;
 111         struct mutex mutex;
 112         struct xenbus_device *xbdev;
 113         struct gendisk *gd;
 114         int vdevice;
 115         blkif_vdev_t handle;
 116         enum blkif_state connected;
 117         int ring_ref;
 118         struct blkif_front_ring ring;
 119         unsigned int evtchn, irq;
 120         struct request_queue *rq;
 121         struct work_struct work;
 122         struct gnttab_free_callback callback;
 123         struct blk_shadow shadow[BLK_RING_SIZE];
 124         struct list_head grants;
 125         struct list_head indirect_pages;
 126         unsigned int persistent_gnts_c;
 127         unsigned long shadow_free;
 128         unsigned int feature_flush;
 129         unsigned int feature_discard:1;
 130         unsigned int feature_secdiscard:1;
 131         unsigned int discard_granularity;
 132         unsigned int discard_alignment;
 133         unsigned int feature_persistent:1;
 134         unsigned int max_indirect_segments;
 135         int is_ready;
 136 };
 137
 138 static unsigned int nr_minors;
 139 static unsigned long *minors;
 140 static DEFINE_SPINLOCK(minor_lock);
 141
 142 #define MAXIMUM_OUTSTANDING_BLOCK_REQS \
 143         (BLKIF_MAX_SEGMENTS_PER_REQUEST * BLK_RING_SIZE)
 144 #define GRANT_INVALID_REF       0
 145
 146 #define PARTS_PER_DISK          16
 147 #define PARTS_PER_EXT_DISK      256
 148
 149 #define BLKIF_MAJOR(dev) ((dev)>>8)
 150 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 151
 152 #define EXT_SHIFT 28
 153 #define EXTENDED (1<<EXT_SHIFT)
 154 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 155 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 156 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 157 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 158 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 159 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 160
 161 #define DEV_NAME        "xvd"   /* name in /dev */
 162
 163 #define SEGS_PER_INDIRECT_FRAME \
 164         (PAGE_SIZE/sizeof(struct blkif_request_segment))
 165 #define INDIRECT_GREFS(_segs) \
 166         ((_segs + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
 167
 168 static int blkfront_setup_indirect(struct blkfront_info *info);
 169
 170 static int get_id_from_freelist(struct blkfront_info *info)
 171 {
 172         unsigned long free = info->shadow_free;
 173         BUG_ON(free >= BLK_RING_SIZE);
 174         info->shadow_free = info->shadow[free].req.u.rw.id;
 175         info->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 176         return free;
 177 }
 178
 179 static int add_id_to_freelist(struct blkfront_info *info,
 180                                unsigned long id)
 181 {
 182         if (info->shadow[id].req.u.rw.id != id)
 183                 return -EINVAL;
 184         if (info->shadow[id].request == NULL)
 185                 return -EINVAL;
 186         info->shadow[id].req.u.rw.id  = info->shadow_free;
 187         info->shadow[id].request = NULL;
 188         info->shadow_free = id;
 189         return 0;
 190 }
 191
 192 static int fill_grant_buffer(struct blkfront_info *info, int num)
 193 {
 194         struct page *granted_page;
 195         struct grant *gnt_list_entry, *n;
 196         int i = 0;
 197
 198         while(i < num) {
 199                 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
 200                 if (!gnt_list_entry)
 201                         goto out_of_memory;
 202
 203                 if (info->feature_persistent) {
 204                         granted_page = alloc_page(GFP_NOIO);
 205                         if (!granted_page) {
 206                                 kfree(gnt_list_entry);
 207                                 goto out_of_memory;
 208                         }
 209                         gnt_list_entry->pfn = page_to_pfn(granted_page);
 210                 }
 211
 212                 gnt_list_entry->gref = GRANT_INVALID_REF;
 213                 list_add(&gnt_list_entry->node, &info->grants);
 214                 i++;
 215         }
 216
 217         return 0;
 218
 219 out_of_memory:
 220         list_for_each_entry_safe(gnt_list_entry, n,
 221                                  &info->grants, node) {
 222                 list_del(&gnt_list_entry->node);
 223                 if (info->feature_persistent)
 224                         __free_page(pfn_to_page(gnt_list_entry->pfn));
 225                 kfree(gnt_list_entry);
 226                 i--;
 227         }
 228         BUG_ON(i != 0);
 229         return -ENOMEM;
 230 }
 231
 232 static struct grant *get_grant(grant_ref_t *gref_head,
 233                                unsigned long pfn,
 234                                struct blkfront_info *info)
 235 {
 236         struct grant *gnt_list_entry;
 237         unsigned long buffer_mfn;
 238
 239         BUG_ON(list_empty(&info->grants));
 240         gnt_list_entry = list_first_entry(&info->grants, struct grant,
 241                                           node);
 242         list_del(&gnt_list_entry->node);
 243
 244         if (gnt_list_entry->gref != GRANT_INVALID_REF) {
 245                 info->persistent_gnts_c--;
 246                 return gnt_list_entry;
 247         }
 248
 249         /* Assign a gref to this page */
 250         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 251         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 252         if (!info->feature_persistent) {
 253                 BUG_ON(!pfn);
 254                 gnt_list_entry->pfn = pfn;
 255         }
 256         buffer_mfn = pfn_to_mfn(gnt_list_entry->pfn);
 257         gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
 258                                         info->xbdev->otherend_id,
 259                                         buffer_mfn, 0);
 260         return gnt_list_entry;
 261 }
 262
 263 static const char *op_name(int op)
 264 {
 265         static const char *const names[] = {
 266                 [BLKIF_OP_READ] = "read",
 267                 [BLKIF_OP_WRITE] = "write",
 268                 [BLKIF_OP_WRITE_BARRIER] = "barrier",
 269                 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
 270                 [BLKIF_OP_DISCARD] = "discard" };
 271
 272         if (op < 0 || op >= ARRAY_SIZE(names))
 273                 return "unknown";
 274
 275         if (!names[op])
 276                 return "reserved";
 277
 278         return names[op];
 279 }
 280 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 281 {
 282         unsigned int end = minor + nr;
 283         int rc;
 284
 285         if (end > nr_minors) {
 286                 unsigned long *bitmap, *old;
 287
 288                 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 289                                  GFP_KERNEL);
 290                 if (bitmap == NULL)
 291                         return -ENOMEM;
 292
 293                 spin_lock(&minor_lock);
 294                 if (end > nr_minors) {
 295                         old = minors;
 296                         memcpy(bitmap, minors,
 297                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 298                         minors = bitmap;
 299                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 300                 } else
 301                         old = bitmap;
 302                 spin_unlock(&minor_lock);
 303                 kfree(old);
 304         }
 305
 306         spin_lock(&minor_lock);
 307         if (find_next_bit(minors, end, minor) >= end) {
 308                 bitmap_set(minors, minor, nr);
 309                 rc = 0;
 310         } else
 311                 rc = -EBUSY;
 312         spin_unlock(&minor_lock);
 313
 314         return rc;
 315 }
 316
 317 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 318 {
 319         unsigned int end = minor + nr;
 320
 321         BUG_ON(end > nr_minors);
 322         spin_lock(&minor_lock);
 323         bitmap_clear(minors,  minor, nr);
 324         spin_unlock(&minor_lock);
 325 }
 326
 327 static void blkif_restart_queue_callback(void *arg)
 328 {
 329         struct blkfront_info *info = (struct blkfront_info *)arg;
 330         schedule_work(&info->work);
 331 }
 332
 333 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 334 {
 335         /* We don't have real geometry info, but let's at least return
 336            values consistent with the size of the device */
 337         sector_t nsect = get_capacity(bd->bd_disk);
 338         sector_t cylinders = nsect;
 339
 340         hg->heads = 0xff;
 341         hg->sectors = 0x3f;
 342         sector_div(cylinders, hg->heads * hg->sectors);
 343         hg->cylinders = cylinders;
 344         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 345                 hg->cylinders = 0xffff;
 346         return 0;
 347 }
 348
 349 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 350                        unsigned command, unsigned long argument)
 351 {
 352         struct blkfront_info *info = bdev->bd_disk->private_data;
 353         int i;
 354
 355         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 356                 command, (long)argument);
 357
 358         switch (command) {
 359         case CDROMMULTISESSION:
 360                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 361                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 362                         if (put_user(0, (char __user *)(argument + i)))
 363                                 return -EFAULT;
 364                 return 0;
 365
 366         case CDROM_GET_CAPABILITY: {
 367                 struct gendisk *gd = info->gd;
 368                 if (gd->flags & GENHD_FL_CD)
 369                         return 0;
 370                 return -EINVAL;
 371         }
 372
 373         default:
 374                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 375                   command);*/
 376                 return -EINVAL; /* same return as native Linux */
 377         }
 378
 379         return 0;
 380 }
 381
 382 /*
 383  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 384  * and writes are handled as expected.
 385  *
 386  * @req: a request struct
 387  */
 388 static int blkif_queue_request(struct request *req)
 389 {
 390         struct blkfront_info *info = req->rq_disk->private_data;
 391         struct blkif_request *ring_req;
 392         unsigned long id;
 393         unsigned int fsect, lsect;
 394         int i, ref, n;
 395         struct blkif_request_segment *segments = NULL;
 396
 397         /*
 398          * Used to store if we are able to queue the request by just using
 399          * existing persistent grants, or if we have to get new grants,
 400          * as there are not sufficiently many free.
 401          */
 402         bool new_persistent_gnts;
 403         grant_ref_t gref_head;
 404         struct grant *gnt_list_entry = NULL;
 405         struct scatterlist *sg;
 406         int nseg, max_grefs;
 407
 408         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
 409                 return 1;
 410
 411         max_grefs = req->nr_phys_segments;
 412         if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
 413                 /*
 414                  * If we are using indirect segments we need to account
 415                  * for the indirect grefs used in the request.
 416                  */
 417                 max_grefs += INDIRECT_GREFS(req->nr_phys_segments);
 418
 419         /* Check if we have enough grants to allocate a requests */
 420         if (info->persistent_gnts_c < max_grefs) {
 421                 new_persistent_gnts = 1;
 422                 if (gnttab_alloc_grant_references(
 423                     max_grefs - info->persistent_gnts_c,
 424                     &gref_head) < 0) {
 425                         gnttab_request_free_callback(
 426                                 &info->callback,
 427                                 blkif_restart_queue_callback,
 428                                 info,
 429                                 max_grefs);
 430                         return 1;
 431                 }
 432         } else
 433                 new_persistent_gnts = 0;
 434
 435         /* Fill out a communications ring structure. */
 436         ring_req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
 437         id = get_id_from_freelist(info);
 438         info->shadow[id].request = req;
 439
 440         if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE))) {
 441                 ring_req->operation = BLKIF_OP_DISCARD;
 442                 ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
 443                 ring_req->u.discard.id = id;
 444                 ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
 445                 if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
 446                         ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
 447                 else
 448                         ring_req->u.discard.flag = 0;
 449         } else {
 450                 BUG_ON(info->max_indirect_segments == 0 &&
 451                        req->nr_phys_segments > BLKIF_MAX_SEGMENTS_PER_REQUEST);
 452                 BUG_ON(info->max_indirect_segments &&
 453                        req->nr_phys_segments > info->max_indirect_segments);
 454                 nseg = blk_rq_map_sg(req->q, req, info->shadow[id].sg);
 455                 ring_req->u.rw.id = id;
 456                 if (nseg > BLKIF_MAX_SEGMENTS_PER_REQUEST) {
 457                         /*
 458                          * The indirect operation can only be a BLKIF_OP_READ or
 459                          * BLKIF_OP_WRITE
 460                          */
 461                         BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
 462                         ring_req->operation = BLKIF_OP_INDIRECT;
 463                         ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
 464                                 BLKIF_OP_WRITE : BLKIF_OP_READ;
 465                         ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
 466                         ring_req->u.indirect.handle = info->handle;
 467                         ring_req->u.indirect.nr_segments = nseg;
 468                 } else {
 469                         ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 470                         ring_req->u.rw.handle = info->handle;
 471                         ring_req->operation = rq_data_dir(req) ?
 472                                 BLKIF_OP_WRITE : BLKIF_OP_READ;
 473                         if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
 474                                 /*
 475                                  * Ideally we can do an unordered flush-to-disk. In case the
 476                                  * backend onlysupports barriers, use that. A barrier request
 477                                  * a superset of FUA, so we can implement it the same
 478                                  * way.  (It's also a FLUSH+FUA, since it is
 479                                  * guaranteed ordered WRT previous writes.)
 480                                  */
 481                                 switch (info->feature_flush &
 482                                         ((REQ_FLUSH|REQ_FUA))) {
 483                                 case REQ_FLUSH|REQ_FUA:
 484                                         ring_req->operation =
 485                                                 BLKIF_OP_WRITE_BARRIER;
 486                                         break;
 487                                 case REQ_FLUSH:
 488                                         ring_req->operation =
 489                                                 BLKIF_OP_FLUSH_DISKCACHE;
 490                                         break;
 491                                 default:
 492                                         ring_req->operation = 0;
 493                                 }
 494                         }
 495                         ring_req->u.rw.nr_segments = nseg;
 496                 }
 497                 for_each_sg(info->shadow[id].sg, sg, nseg, i) {
 498                         fsect = sg->offset >> 9;
 499                         lsect = fsect + (sg->length >> 9) - 1;
 500
 501                         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 502                             (i % SEGS_PER_INDIRECT_FRAME == 0)) {
 503                                 unsigned long uninitialized_var(pfn);
 504
 505                                 if (segments)
 506                                         kunmap_atomic(segments);
 507
 508                                 n = i / SEGS_PER_INDIRECT_FRAME;
 509                                 if (!info->feature_persistent) {
 510                                         struct page *indirect_page;
 511
 512                                         /* Fetch a pre-allocated page to use for indirect grefs */
 513                                         BUG_ON(list_empty(&info->indirect_pages));
 514                                         indirect_page = list_first_entry(&info->indirect_pages,
 515                                                                          struct page, lru);
 516                                         list_del(&indirect_page->lru);
 517                                         pfn = page_to_pfn(indirect_page);
 518                                 }
 519                                 gnt_list_entry = get_grant(&gref_head, pfn, info);
 520                                 info->shadow[id].indirect_grants[n] = gnt_list_entry;
 521                                 segments = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
 522                                 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 523                         }
 524
 525                         gnt_list_entry = get_grant(&gref_head, page_to_pfn(sg_page(sg)), info);
 526                         ref = gnt_list_entry->gref;
 527
 528                         info->shadow[id].grants_used[i] = gnt_list_entry;
 529
 530                         if (rq_data_dir(req) && info->feature_persistent) {
 531                                 char *bvec_data;
 532                                 void *shared_data;
 533
 534                                 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
 535
 536                                 shared_data = kmap_atomic(pfn_to_page(gnt_list_entry->pfn));
 537                                 bvec_data = kmap_atomic(sg_page(sg));
 538
 539                                 /*
 540                                  * this does not wipe data stored outside the
 541                                  * range sg->offset..sg->offset+sg->length.
 542                                  * Therefore, blkback *could* see data from
 543                                  * previous requests. This is OK as long as
 544                                  * persistent grants are shared with just one
 545                                  * domain. It may need refactoring if this
 546                                  * changes
 547                                  */
 548                                 memcpy(shared_data + sg->offset,
 549                                        bvec_data   + sg->offset,
 550                                        sg->length);
 551
 552                                 kunmap_atomic(bvec_data);
 553                                 kunmap_atomic(shared_data);
 554                         }
 555                         if (ring_req->operation != BLKIF_OP_INDIRECT) {
 556                                 ring_req->u.rw.seg[i] =
 557                                                 (struct blkif_request_segment) {
 558                                                         .gref       = ref,
 559                                                         .first_sect = fsect,
 560                                                         .last_sect  = lsect };
 561                         } else {
 562                                 n = i % SEGS_PER_INDIRECT_FRAME;
 563                                 segments[n] =
 564                                         (struct blkif_request_segment) {
 565                                                         .gref       = ref,
 566                                                         .first_sect = fsect,
 567                                                         .last_sect  = lsect };
 568                         }
 569                 }
 570                 if (segments)
 571                         kunmap_atomic(segments);
 572         }
 573
 574         info->ring.req_prod_pvt++;
 575
 576         /* Keep a private copy so we can reissue requests when recovering. */
 577         info->shadow[id].req = *ring_req;
 578
 579         if (new_persistent_gnts)
 580                 gnttab_free_grant_references(gref_head);
 581
 582         return 0;
 583 }
 584
 585
 586 static inline void flush_requests(struct blkfront_info *info)
 587 {
 588         int notify;
 589
 590         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
 591
 592         if (notify)
 593                 notify_remote_via_irq(info->irq);
 594 }
 595
 596 static inline bool blkif_request_flush_invalid(struct request *req,
 597                                                struct blkfront_info *info)
 598 {
 599         return ((req->cmd_type != REQ_TYPE_FS) ||
 600                 ((req->cmd_flags & REQ_FLUSH) &&
 601                  !(info->feature_flush & REQ_FLUSH)) ||
 602                 ((req->cmd_flags & REQ_FUA) &&
 603                  !(info->feature_flush & REQ_FUA)));
 604 }
 605
 606 /*
 607  * do_blkif_request
 608  *  read a block; request is in a request queue
 609  */
 610 static void do_blkif_request(struct request_queue *rq)
 611 {
 612         struct blkfront_info *info = NULL;
 613         struct request *req;
 614         int queued;
 615
 616         pr_debug("Entered do_blkif_request\n");
 617
 618         queued = 0;
 619
 620         while ((req = blk_peek_request(rq)) != NULL) {
 621                 info = req->rq_disk->private_data;
 622
 623                 if (RING_FULL(&info->ring))
 624                         goto wait;
 625
 626                 blk_start_request(req);
 627
 628                 if (blkif_request_flush_invalid(req, info)) {
 629                         __blk_end_request_all(req, -EOPNOTSUPP);
 630                         continue;
 631                 }
 632
 633                 pr_debug("do_blk_req %p: cmd %p, sec %lx, "
 634                          "(%u/%u) [%s]\n",
 635                          req, req->cmd, (unsigned long)blk_rq_pos(req),
 636                          blk_rq_cur_sectors(req), blk_rq_sectors(req),
 637                          rq_data_dir(req) ? "write" : "read");
 638
 639                 if (blkif_queue_request(req)) {
 640                         blk_requeue_request(rq, req);
 641 wait:
 642                         /* Avoid pointless unplugs. */
 643                         blk_stop_queue(rq);
 644                         break;
 645                 }
 646
 647                 queued++;
 648         }
 649
 650         if (queued != 0)
 651                 flush_requests(info);
 652 }
 653
 654 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 655                                 unsigned int physical_sector_size,
 656                                 unsigned int segments)
 657 {
 658         struct request_queue *rq;
 659         struct blkfront_info *info = gd->private_data;
 660
 661         rq = blk_init_queue(do_blkif_request, &info->io_lock);
 662         if (rq == NULL)
 663                 return -1;
 664
 665         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
 666
 667         if (info->feature_discard) {
 668                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
 669                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
 670                 rq->limits.discard_granularity = info->discard_granularity;
 671                 rq->limits.discard_alignment = info->discard_alignment;
 672                 if (info->feature_secdiscard)
 673                         queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
 674         }
 675
 676         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 677         blk_queue_logical_block_size(rq, sector_size);
 678         blk_queue_physical_block_size(rq, physical_sector_size);
 679         blk_queue_max_hw_sectors(rq, (segments * PAGE_SIZE) / 512);
 680
 681         /* Each segment in a request is up to an aligned page in size. */
 682         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 683         blk_queue_max_segment_size(rq, PAGE_SIZE);
 684
 685         /* Ensure a merged request will fit in a single I/O ring slot. */
 686         blk_queue_max_segments(rq, segments);
 687
 688         /* Make sure buffer addresses are sector-aligned. */
 689         blk_queue_dma_alignment(rq, 511);
 690
 691         /* Make sure we don't use bounce buffers. */
 692         blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
 693
 694         gd->queue = rq;
 695
 696         return 0;
 697 }
 698
 699 static const char *flush_info(unsigned int feature_flush)
 700 {
 701         switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) {
 702         case REQ_FLUSH|REQ_FUA:
 703                 return "barrier: enabled;";
 704         case REQ_FLUSH:
 705                 return "flush diskcache: enabled;";
 706         default:
 707                 return "barrier or flush: disabled;";
 708         }
 709 }
 710
 711 static void xlvbd_flush(struct blkfront_info *info)
 712 {
 713         blk_queue_flush(info->rq, info->feature_flush);
 714         pr_info("blkfront: %s: %s %s %s %s %s\n",
 715                 info->gd->disk_name, flush_info(info->feature_flush),
 716                 "persistent grants:", info->feature_persistent ?
 717                 "enabled;" : "disabled;", "indirect descriptors:",
 718                 info->max_indirect_segments ? "enabled;" : "disabled;");
 719 }
 720
 721 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
 722 {
 723         int major;
 724         major = BLKIF_MAJOR(vdevice);
 725         *minor = BLKIF_MINOR(vdevice);
 726         switch (major) {
 727                 case XEN_IDE0_MAJOR:
 728                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
 729                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
 730                                 EMULATED_HD_DISK_MINOR_OFFSET;
 731                         break;
 732                 case XEN_IDE1_MAJOR:
 733                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
 734                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
 735                                 EMULATED_HD_DISK_MINOR_OFFSET;
 736                         break;
 737                 case XEN_SCSI_DISK0_MAJOR:
 738                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
 739                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
 740                         break;
 741                 case XEN_SCSI_DISK1_MAJOR:
 742                 case XEN_SCSI_DISK2_MAJOR:
 743                 case XEN_SCSI_DISK3_MAJOR:
 744                 case XEN_SCSI_DISK4_MAJOR:
 745                 case XEN_SCSI_DISK5_MAJOR:
 746                 case XEN_SCSI_DISK6_MAJOR:
 747                 case XEN_SCSI_DISK7_MAJOR:
 748                         *offset = (*minor / PARTS_PER_DISK) +
 749                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
 750                                 EMULATED_SD_DISK_NAME_OFFSET;
 751                         *minor = *minor +
 752                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
 753                                 EMULATED_SD_DISK_MINOR_OFFSET;
 754                         break;
 755                 case XEN_SCSI_DISK8_MAJOR:
 756                 case XEN_SCSI_DISK9_MAJOR:
 757                 case XEN_SCSI_DISK10_MAJOR:
 758                 case XEN_SCSI_DISK11_MAJOR:
 759                 case XEN_SCSI_DISK12_MAJOR:
 760                 case XEN_SCSI_DISK13_MAJOR:
 761                 case XEN_SCSI_DISK14_MAJOR:
 762                 case XEN_SCSI_DISK15_MAJOR:
 763                         *offset = (*minor / PARTS_PER_DISK) +
 764                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
 765                                 EMULATED_SD_DISK_NAME_OFFSET;
 766                         *minor = *minor +
 767                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
 768                                 EMULATED_SD_DISK_MINOR_OFFSET;
 769                         break;
 770                 case XENVBD_MAJOR:
 771                         *offset = *minor / PARTS_PER_DISK;
 772                         break;
 773                 default:
 774                         printk(KERN_WARNING "blkfront: your disk configuration is "
 775                                         "incorrect, please use an xvd device instead\n");
 776                         return -ENODEV;
 777         }
 778         return 0;
 779 }
 780
 781 static char *encode_disk_name(char *ptr, unsigned int n)
 782 {
 783         if (n >= 26)
 784                 ptr = encode_disk_name(ptr, n / 26 - 1);
 785         *ptr = 'a' + n % 26;
 786         return ptr + 1;
 787 }
 788
 789 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 790                                struct blkfront_info *info,
 791                                u16 vdisk_info, u16 sector_size,
 792                                unsigned int physical_sector_size)
 793 {
 794         struct gendisk *gd;
 795         int nr_minors = 1;
 796         int err;
 797         unsigned int offset;
 798         int minor;
 799         int nr_parts;
 800         char *ptr;
 801
 802         BUG_ON(info->gd != NULL);
 803         BUG_ON(info->rq != NULL);
 804
 805         if ((info->vdevice>>EXT_SHIFT) > 1) {
 806                 /* this is above the extended range; something is wrong */
 807                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
 808                 return -ENODEV;
 809         }
 810
 811         if (!VDEV_IS_EXTENDED(info->vdevice)) {
 812                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
 813                 if (err)
 814                         return err;
 815                 nr_parts = PARTS_PER_DISK;
 816         } else {
 817                 minor = BLKIF_MINOR_EXT(info->vdevice);
 818                 nr_parts = PARTS_PER_EXT_DISK;
 819                 offset = minor / nr_parts;
 820                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
 821                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
 822                                         "emulated IDE disks,\n\t choose an xvd device name"
 823                                         "from xvde on\n", info->vdevice);
 824         }
 825         if (minor >> MINORBITS) {
 826                 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
 827                         info->vdevice, minor);
 828                 return -ENODEV;
 829         }
 830
 831         if ((minor % nr_parts) == 0)
 832                 nr_minors = nr_parts;
 833
 834         err = xlbd_reserve_minors(minor, nr_minors);
 835         if (err)
 836                 goto out;
 837         err = -ENODEV;
 838
 839         gd = alloc_disk(nr_minors);
 840         if (gd == NULL)
 841                 goto release;
 842
 843         strcpy(gd->disk_name, DEV_NAME);
 844         ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
 845         BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
 846         if (nr_minors > 1)
 847                 *ptr = 0;
 848         else
 849                 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
 850                          "%d", minor & (nr_parts - 1));
 851
 852         gd->major = XENVBD_MAJOR;
 853         gd->first_minor = minor;
 854         gd->fops = &xlvbd_block_fops;
 855         gd->private_data = info;
 856         gd->driverfs_dev = &(info->xbdev->dev);
 857         set_capacity(gd, capacity);
 858
 859         if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
 860                                  info->max_indirect_segments ? :
 861                                  BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
 862                 del_gendisk(gd);
 863                 goto release;
 864         }
 865
 866         info->rq = gd->queue;
 867         info->gd = gd;
 868
 869         xlvbd_flush(info);
 870
 871         if (vdisk_info & VDISK_READONLY)
 872                 set_disk_ro(gd, 1);
 873
 874         if (vdisk_info & VDISK_REMOVABLE)
 875                 gd->flags |= GENHD_FL_REMOVABLE;
 876
 877         if (vdisk_info & VDISK_CDROM)
 878                 gd->flags |= GENHD_FL_CD;
 879
 880         return 0;
 881
 882  release:
 883         xlbd_release_minors(minor, nr_minors);
 884  out:
 885         return err;
 886 }
 887
 888 static void xlvbd_release_gendisk(struct blkfront_info *info)
 889 {
 890         unsigned int minor, nr_minors;
 891         unsigned long flags;
 892
 893         if (info->rq == NULL)
 894                 return;
 895
 896         spin_lock_irqsave(&info->io_lock, flags);
 897
 898         /* No more blkif_request(). */
 899         blk_stop_queue(info->rq);
 900
 901         /* No more gnttab callback work. */
 902         gnttab_cancel_free_callback(&info->callback);
 903         spin_unlock_irqrestore(&info->io_lock, flags);
 904
 905         /* Flush gnttab callback work. Must be done with no locks held. */
 906         flush_work(&info->work);
 907
 908         del_gendisk(info->gd);
 909
 910         minor = info->gd->first_minor;
 911         nr_minors = info->gd->minors;
 912         xlbd_release_minors(minor, nr_minors);
 913
 914         blk_cleanup_queue(info->rq);
 915         info->rq = NULL;
 916
 917         put_disk(info->gd);
 918         info->gd = NULL;
 919 }
 920
 921 static void kick_pending_request_queues(struct blkfront_info *info)
 922 {
 923         if (!RING_FULL(&info->ring)) {
 924                 /* Re-enable calldowns. */
 925                 blk_start_queue(info->rq);
 926                 /* Kick things off immediately. */
 927                 do_blkif_request(info->rq);
 928         }
 929 }
 930
 931 static void blkif_restart_queue(struct work_struct *work)
 932 {
 933         struct blkfront_info *info = container_of(work, struct blkfront_info, work);
 934
 935         spin_lock_irq(&info->io_lock);
 936         if (info->connected == BLKIF_STATE_CONNECTED)
 937                 kick_pending_request_queues(info);
 938         spin_unlock_irq(&info->io_lock);
 939 }
 940
 941 static void blkif_free(struct blkfront_info *info, int suspend)
 942 {
 943         struct grant *persistent_gnt;
 944         struct grant *n;
 945         int i, j, segs;
 946
 947         /* Prevent new requests being issued until we fix things up. */
 948         spin_lock_irq(&info->io_lock);
 949         info->connected = suspend ?
 950                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
 951         /* No more blkif_request(). */
 952         if (info->rq)
 953                 blk_stop_queue(info->rq);
 954
 955         /* Remove all persistent grants */
 956         if (!list_empty(&info->grants)) {
 957                 list_for_each_entry_safe(persistent_gnt, n,
 958                                          &info->grants, node) {
 959                         list_del(&persistent_gnt->node);
 960                         if (persistent_gnt->gref != GRANT_INVALID_REF) {
 961                                 gnttab_end_foreign_access(persistent_gnt->gref,
 962                                                           0, 0UL);
 963                                 info->persistent_gnts_c--;
 964                         }
 965                         if (info->feature_persistent)
 966                                 __free_page(pfn_to_page(persistent_gnt->pfn));
 967                         kfree(persistent_gnt);
 968                 }
 969         }
 970         BUG_ON(info->persistent_gnts_c != 0);
 971
 972         /*
 973          * Remove indirect pages, this only happens when using indirect
 974          * descriptors but not persistent grants
 975          */
 976         if (!list_empty(&info->indirect_pages)) {
 977                 struct page *indirect_page, *n;
 978
 979                 BUG_ON(info->feature_persistent);
 980                 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
 981                         list_del(&indirect_page->lru);
 982                         __free_page(indirect_page);
 983                 }
 984         }
 985
 986         for (i = 0; i < BLK_RING_SIZE; i++) {
 987                 /*
 988                  * Clear persistent grants present in requests already
 989                  * on the shared ring
 990                  */
 991                 if (!info->shadow[i].request)
 992                         goto free_shadow;
 993
 994                 segs = info->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
 995                        info->shadow[i].req.u.indirect.nr_segments :
 996                        info->shadow[i].req.u.rw.nr_segments;
 997                 for (j = 0; j < segs; j++) {
 998                         persistent_gnt = info->shadow[i].grants_used[j];
 999                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1000                         if (info->feature_persistent)
1001                                 __free_page(pfn_to_page(persistent_gnt->pfn));
1002                         kfree(persistent_gnt);
1003                 }
1004
1005                 if (info->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1006                         /*
1007                          * If this is not an indirect operation don't try to
1008                          * free indirect segments
1009                          */
1010                         goto free_shadow;
1011
1012                 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1013                         persistent_gnt = info->shadow[i].indirect_grants[j];
1014                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1015                         __free_page(pfn_to_page(persistent_gnt->pfn));
1016                         kfree(persistent_gnt);
1017                 }
1018
1019 free_shadow:
1020                 kfree(info->shadow[i].grants_used);
1021                 info->shadow[i].grants_used = NULL;
1022                 kfree(info->shadow[i].indirect_grants);
1023                 info->shadow[i].indirect_grants = NULL;
1024                 kfree(info->shadow[i].sg);
1025                 info->shadow[i].sg = NULL;
1026         }
1027
1028         /* No more gnttab callback work. */
1029         gnttab_cancel_free_callback(&info->callback);
1030         spin_unlock_irq(&info->io_lock);
1031
1032         /* Flush gnttab callback work. Must be done with no locks held. */
1033         flush_work(&info->work);
1034
1035         /* Free resources associated with old device channel. */
1036         if (info->ring_ref != GRANT_INVALID_REF) {
1037                 gnttab_end_foreign_access(info->ring_ref, 0,
1038                                           (unsigned long)info->ring.sring);
1039                 info->ring_ref = GRANT_INVALID_REF;
1040                 info->ring.sring = NULL;
1041         }
1042         if (info->irq)
1043                 unbind_from_irqhandler(info->irq, info);
1044         info->evtchn = info->irq = 0;
1045
1046 }
1047
1048 static void blkif_completion(struct blk_shadow *s, struct blkfront_info *info,
1049                              struct blkif_response *bret)
1050 {
1051         int i = 0;
1052         struct scatterlist *sg;
1053         char *bvec_data;
1054         void *shared_data;
1055         int nseg;
1056
1057         nseg = s->req.operation == BLKIF_OP_INDIRECT ?
1058                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1059
1060         if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1061                 /*
1062                  * Copy the data received from the backend into the bvec.
1063                  * Since bv_offset can be different than 0, and bv_len different
1064                  * than PAGE_SIZE, we have to keep track of the current offset,
1065                  * to be sure we are copying the data from the right shared page.
1066                  */
1067                 for_each_sg(s->sg, sg, nseg, i) {
1068                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1069                         shared_data = kmap_atomic(
1070                                 pfn_to_page(s->grants_used[i]->pfn));
1071                         bvec_data = kmap_atomic(sg_page(sg));
1072                         memcpy(bvec_data   + sg->offset,
1073                                shared_data + sg->offset,
1074                                sg->length);
1075                         kunmap_atomic(bvec_data);
1076                         kunmap_atomic(shared_data);
1077                 }
1078         }
1079         /* Add the persistent grant into the list of free grants */
1080         for (i = 0; i < nseg; i++) {
1081                 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1082                         /*
1083                          * If the grant is still mapped by the backend (the
1084                          * backend has chosen to make this grant persistent)
1085                          * we add it at the head of the list, so it will be
1086                          * reused first.
1087                          */
1088                         if (!info->feature_persistent)
1089                                 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1090                                                      s->grants_used[i]->gref);
1091                         list_add(&s->grants_used[i]->node, &info->grants);
1092                         info->persistent_gnts_c++;
1093                 } else {
1094                         /*
1095                          * If the grant is not mapped by the backend we end the
1096                          * foreign access and add it to the tail of the list,
1097                          * so it will not be picked again unless we run out of
1098                          * persistent grants.
1099                          */
1100                         gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1101                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1102                         list_add_tail(&s->grants_used[i]->node, &info->grants);
1103                 }
1104         }
1105         if (s->req.operation == BLKIF_OP_INDIRECT) {
1106                 for (i = 0; i < INDIRECT_GREFS(nseg); i++) {
1107                         if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1108                                 if (!info->feature_persistent)
1109                                         pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1110                                                              s->indirect_grants[i]->gref);
1111                                 list_add(&s->indirect_grants[i]->node, &info->grants);
1112                                 info->persistent_gnts_c++;
1113                         } else {
1114                                 struct page *indirect_page;
1115
1116                                 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1117                                 /*
1118                                  * Add the used indirect page back to the list of
1119                                  * available pages for indirect grefs.
1120                                  */
1121                                 indirect_page = pfn_to_page(s->indirect_grants[i]->pfn);
1122                                 list_add(&indirect_page->lru, &info->indirect_pages);
1123                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1124                                 list_add_tail(&s->indirect_grants[i]->node, &info->grants);
1125                         }
1126                 }
1127         }
1128 }
1129
1130 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1131 {
1132         struct request *req;
1133         struct blkif_response *bret;
1134         RING_IDX i, rp;
1135         unsigned long flags;
1136         struct blkfront_info *info = (struct blkfront_info *)dev_id;
1137         int error;
1138
1139         spin_lock_irqsave(&info->io_lock, flags);
1140
1141         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1142                 spin_unlock_irqrestore(&info->io_lock, flags);
1143                 return IRQ_HANDLED;
1144         }
1145
1146  again:
1147         rp = info->ring.sring->rsp_prod;
1148         rmb(); /* Ensure we see queued responses up to 'rp'. */
1149
1150         for (i = info->ring.rsp_cons; i != rp; i++) {
1151                 unsigned long id;
1152
1153                 bret = RING_GET_RESPONSE(&info->ring, i);
1154                 id   = bret->id;
1155                 /*
1156                  * The backend has messed up and given us an id that we would
1157                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1158                  * look in get_id_from_freelist.
1159                  */
1160                 if (id >= BLK_RING_SIZE) {
1161                         WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1162                              info->gd->disk_name, op_name(bret->operation), id);
1163                         /* We can't safely get the 'struct request' as
1164                          * the id is busted. */
1165                         continue;
1166                 }
1167                 req  = info->shadow[id].request;
1168
1169                 if (bret->operation != BLKIF_OP_DISCARD)
1170                         blkif_completion(&info->shadow[id], info, bret);
1171
1172                 if (add_id_to_freelist(info, id)) {
1173                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1174                              info->gd->disk_name, op_name(bret->operation), id);
1175                         continue;
1176                 }
1177
1178                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1179                 switch (bret->operation) {
1180                 case BLKIF_OP_DISCARD:
1181                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1182                                 struct request_queue *rq = info->rq;
1183                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1184                                            info->gd->disk_name, op_name(bret->operation));
1185                                 error = -EOPNOTSUPP;
1186                                 info->feature_discard = 0;
1187                                 info->feature_secdiscard = 0;
1188                                 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1189                                 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1190                         }
1191                         __blk_end_request_all(req, error);
1192                         break;
1193                 case BLKIF_OP_FLUSH_DISKCACHE:
1194                 case BLKIF_OP_WRITE_BARRIER:
1195                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1196                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1197                                        info->gd->disk_name, op_name(bret->operation));
1198                                 error = -EOPNOTSUPP;
1199                         }
1200                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1201                                      info->shadow[id].req.u.rw.nr_segments == 0)) {
1202                                 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1203                                        info->gd->disk_name, op_name(bret->operation));
1204                                 error = -EOPNOTSUPP;
1205                         }
1206                         if (unlikely(error)) {
1207                                 if (error == -EOPNOTSUPP)
1208                                         error = 0;
1209                                 info->feature_flush = 0;
1210                                 xlvbd_flush(info);
1211                         }
1212                         /* fall through */
1213                 case BLKIF_OP_READ:
1214                 case BLKIF_OP_WRITE:
1215                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
1216                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1217                                         "request: %x\n", bret->status);
1218
1219                         __blk_end_request_all(req, error);
1220                         break;
1221                 default:
1222                         BUG();
1223                 }
1224         }
1225
1226         info->ring.rsp_cons = i;
1227
1228         if (i != info->ring.req_prod_pvt) {
1229                 int more_to_do;
1230                 RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
1231                 if (more_to_do)
1232                         goto again;
1233         } else
1234                 info->ring.sring->rsp_event = i + 1;
1235
1236         kick_pending_request_queues(info);
1237
1238         spin_unlock_irqrestore(&info->io_lock, flags);
1239
1240         return IRQ_HANDLED;
1241 }
1242
1243
1244 static int setup_blkring(struct xenbus_device *dev,
1245                          struct blkfront_info *info)
1246 {
1247         struct blkif_sring *sring;
1248         grant_ref_t gref;
1249         int err;
1250
1251         info->ring_ref = GRANT_INVALID_REF;
1252
1253         sring = (struct blkif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
1254         if (!sring) {
1255                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1256                 return -ENOMEM;
1257         }
1258         SHARED_RING_INIT(sring);
1259         FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
1260
1261         err = xenbus_grant_ring(dev, info->ring.sring, 1, &gref);
1262         if (err < 0) {
1263                 free_page((unsigned long)sring);
1264                 info->ring.sring = NULL;
1265                 goto fail;
1266         }
1267         info->ring_ref = gref;
1268
1269         err = xenbus_alloc_evtchn(dev, &info->evtchn);
1270         if (err)
1271                 goto fail;
1272
1273         err = bind_evtchn_to_irqhandler(info->evtchn, blkif_interrupt, 0,
1274                                         "blkif", info);
1275         if (err <= 0) {
1276                 xenbus_dev_fatal(dev, err,
1277                                  "bind_evtchn_to_irqhandler failed");
1278                 goto fail;
1279         }
1280         info->irq = err;
1281
1282         return 0;
1283 fail:
1284         blkif_free(info, 0);
1285         return err;
1286 }
1287
1288
1289 /* Common code used when first setting up, and when resuming. */
1290 static int talk_to_blkback(struct xenbus_device *dev,
1291                            struct blkfront_info *info)
1292 {
1293         const char *message = NULL;
1294         struct xenbus_transaction xbt;
1295         int err;
1296
1297         /* Create shared ring, alloc event channel. */
1298         err = setup_blkring(dev, info);
1299         if (err)
1300                 goto out;
1301
1302 again:
1303         err = xenbus_transaction_start(&xbt);
1304         if (err) {
1305                 xenbus_dev_fatal(dev, err, "starting transaction");
1306                 goto destroy_blkring;
1307         }
1308
1309         err = xenbus_printf(xbt, dev->nodename,
1310                             "ring-ref", "%u", info->ring_ref);
1311         if (err) {
1312                 message = "writing ring-ref";
1313                 goto abort_transaction;
1314         }
1315         err = xenbus_printf(xbt, dev->nodename,
1316                             "event-channel", "%u", info->evtchn);
1317         if (err) {
1318                 message = "writing event-channel";
1319                 goto abort_transaction;
1320         }
1321         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1322                             XEN_IO_PROTO_ABI_NATIVE);
1323         if (err) {
1324                 message = "writing protocol";
1325                 goto abort_transaction;
1326         }
1327         err = xenbus_printf(xbt, dev->nodename,
1328                             "feature-persistent", "%u", 1);
1329         if (err)
1330                 dev_warn(&dev->dev,
1331                          "writing persistent grants feature to xenbus");
1332
1333         err = xenbus_transaction_end(xbt, 0);
1334         if (err) {
1335                 if (err == -EAGAIN)
1336                         goto again;
1337                 xenbus_dev_fatal(dev, err, "completing transaction");
1338                 goto destroy_blkring;
1339         }
1340
1341         xenbus_switch_state(dev, XenbusStateInitialised);
1342
1343         return 0;
1344
1345  abort_transaction:
1346         xenbus_transaction_end(xbt, 1);
1347         if (message)
1348                 xenbus_dev_fatal(dev, err, "%s", message);
1349  destroy_blkring:
1350         blkif_free(info, 0);
1351  out:
1352         return err;
1353 }
1354
1355 /**
1356  * Entry point to this code when a new device is created.  Allocate the basic
1357  * structures and the ring buffer for communication with the backend, and
1358  * inform the backend of the appropriate details for those.  Switch to
1359  * Initialised state.
1360  */
1361 static int blkfront_probe(struct xenbus_device *dev,
1362                           const struct xenbus_device_id *id)
1363 {
1364         int err, vdevice, i;
1365         struct blkfront_info *info;
1366
1367         /* FIXME: Use dynamic device id if this is not set. */
1368         err = xenbus_scanf(XBT_NIL, dev->nodename,
1369                            "virtual-device", "%i", &vdevice);
1370         if (err != 1) {
1371                 /* go looking in the extended area instead */
1372                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1373                                    "%i", &vdevice);
1374                 if (err != 1) {
1375                         xenbus_dev_fatal(dev, err, "reading virtual-device");
1376                         return err;
1377                 }
1378         }
1379
1380         if (xen_hvm_domain()) {
1381                 char *type;
1382                 int len;
1383                 /* no unplug has been done: do not hook devices != xen vbds */
1384                 if (xen_has_pv_and_legacy_disk_devices()) {
1385                         int major;
1386
1387                         if (!VDEV_IS_EXTENDED(vdevice))
1388                                 major = BLKIF_MAJOR(vdevice);
1389                         else
1390                                 major = XENVBD_MAJOR;
1391
1392                         if (major != XENVBD_MAJOR) {
1393                                 printk(KERN_INFO
1394                                                 "%s: HVM does not support vbd %d as xen block device\n",
1395                                                 __func__, vdevice);
1396                                 return -ENODEV;
1397                         }
1398                 }
1399                 /* do not create a PV cdrom device if we are an HVM guest */
1400                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1401                 if (IS_ERR(type))
1402                         return -ENODEV;
1403                 if (strncmp(type, "cdrom", 5) == 0) {
1404                         kfree(type);
1405                         return -ENODEV;
1406                 }
1407                 kfree(type);
1408         }
1409         info = kzalloc(sizeof(*info), GFP_KERNEL);
1410         if (!info) {
1411                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1412                 return -ENOMEM;
1413         }
1414
1415         mutex_init(&info->mutex);
1416         spin_lock_init(&info->io_lock);
1417         info->xbdev = dev;
1418         info->vdevice = vdevice;
1419         INIT_LIST_HEAD(&info->grants);
1420         INIT_LIST_HEAD(&info->indirect_pages);
1421         info->persistent_gnts_c = 0;
1422         info->connected = BLKIF_STATE_DISCONNECTED;
1423         INIT_WORK(&info->work, blkif_restart_queue);
1424
1425         for (i = 0; i < BLK_RING_SIZE; i++)
1426                 info->shadow[i].req.u.rw.id = i+1;
1427         info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1428
1429         /* Front end dir is a number, which is used as the id. */
1430         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1431         dev_set_drvdata(&dev->dev, info);
1432
1433         err = talk_to_blkback(dev, info);
1434         if (err) {
1435                 kfree(info);
1436                 dev_set_drvdata(&dev->dev, NULL);
1437                 return err;
1438         }
1439
1440         return 0;
1441 }
1442
1443 static void split_bio_end(struct bio *bio, int error)
1444 {
1445         struct split_bio *split_bio = bio->bi_private;
1446
1447         if (error)
1448                 split_bio->err = error;
1449
1450         if (atomic_dec_and_test(&split_bio->pending)) {
1451                 split_bio->bio->bi_phys_segments = 0;
1452                 bio_endio(split_bio->bio, split_bio->err);
1453                 kfree(split_bio);
1454         }
1455         bio_put(bio);
1456 }
1457
1458 static int blkif_recover(struct blkfront_info *info)
1459 {
1460         int i;
1461         struct request *req, *n;
1462         struct blk_shadow *copy;
1463         int rc;
1464         struct bio *bio, *cloned_bio;
1465         struct bio_list bio_list, merge_bio;
1466         unsigned int segs, offset;
1467         int pending, size;
1468         struct split_bio *split_bio;
1469         struct list_head requests;
1470
1471         /* Stage 1: Make a safe copy of the shadow state. */
1472         copy = kmemdup(info->shadow, sizeof(info->shadow),
1473                        GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
1474         if (!copy)
1475                 return -ENOMEM;
1476
1477         /* Stage 2: Set up free list. */
1478         memset(&info->shadow, 0, sizeof(info->shadow));
1479         for (i = 0; i < BLK_RING_SIZE; i++)
1480                 info->shadow[i].req.u.rw.id = i+1;
1481         info->shadow_free = info->ring.req_prod_pvt;
1482         info->shadow[BLK_RING_SIZE-1].req.u.rw.id = 0x0fffffff;
1483
1484         rc = blkfront_setup_indirect(info);
1485         if (rc) {
1486                 kfree(copy);
1487                 return rc;
1488         }
1489
1490         segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
1491         blk_queue_max_segments(info->rq, segs);
1492         bio_list_init(&bio_list);
1493         INIT_LIST_HEAD(&requests);
1494         for (i = 0; i < BLK_RING_SIZE; i++) {
1495                 /* Not in use? */
1496                 if (!copy[i].request)
1497                         continue;
1498
1499                 /*
1500                  * Get the bios in the request so we can re-queue them.
1501                  */
1502                 if (copy[i].request->cmd_flags &
1503                     (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1504                         /*
1505                          * Flush operations don't contain bios, so
1506                          * we need to requeue the whole request
1507                          */
1508                         list_add(&copy[i].request->queuelist, &requests);
1509                         continue;
1510                 }
1511                 merge_bio.head = copy[i].request->bio;
1512                 merge_bio.tail = copy[i].request->biotail;
1513                 bio_list_merge(&bio_list, &merge_bio);
1514                 copy[i].request->bio = NULL;
1515                 blk_end_request_all(copy[i].request, 0);
1516         }
1517
1518         kfree(copy);
1519
1520         /*
1521          * Empty the queue, this is important because we might have
1522          * requests in the queue with more segments than what we
1523          * can handle now.
1524          */
1525         spin_lock_irq(&info->io_lock);
1526         while ((req = blk_fetch_request(info->rq)) != NULL) {
1527                 if (req->cmd_flags &
1528                     (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
1529                         list_add(&req->queuelist, &requests);
1530                         continue;
1531                 }
1532                 merge_bio.head = req->bio;
1533                 merge_bio.tail = req->biotail;
1534                 bio_list_merge(&bio_list, &merge_bio);
1535                 req->bio = NULL;
1536                 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA))
1537                         pr_alert("diskcache flush request found!\n");
1538                 __blk_end_request_all(req, 0);
1539         }
1540         spin_unlock_irq(&info->io_lock);
1541
1542         xenbus_switch_state(info->xbdev, XenbusStateConnected);
1543
1544         spin_lock_irq(&info->io_lock);
1545
1546         /* Now safe for us to use the shared ring */
1547         info->connected = BLKIF_STATE_CONNECTED;
1548
1549         /* Kick any other new requests queued since we resumed */
1550         kick_pending_request_queues(info);
1551
1552         list_for_each_entry_safe(req, n, &requests, queuelist) {
1553                 /* Requeue pending requests (flush or discard) */
1554                 list_del_init(&req->queuelist);
1555                 BUG_ON(req->nr_phys_segments > segs);
1556                 blk_requeue_request(info->rq, req);
1557         }
1558         spin_unlock_irq(&info->io_lock);
1559
1560         while ((bio = bio_list_pop(&bio_list)) != NULL) {
1561                 /* Traverse the list of pending bios and re-queue them */
1562                 if (bio_segments(bio) > segs) {
1563                         /*
1564                          * This bio has more segments than what we can
1565                          * handle, we have to split it.
1566                          */
1567                         pending = (bio_segments(bio) + segs - 1) / segs;
1568                         split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
1569                         BUG_ON(split_bio == NULL);
1570                         atomic_set(&split_bio->pending, pending);
1571                         split_bio->bio = bio;
1572                         for (i = 0; i < pending; i++) {
1573                                 offset = (i * segs * PAGE_SIZE) >> 9;
1574                                 size = min((unsigned int)(segs * PAGE_SIZE) >> 9,
1575                                            (unsigned int)bio_sectors(bio) - offset);
1576                                 cloned_bio = bio_clone(bio, GFP_NOIO);
1577                                 BUG_ON(cloned_bio == NULL);
1578                                 bio_trim(cloned_bio, offset, size);
1579                                 cloned_bio->bi_private = split_bio;
1580                                 cloned_bio->bi_end_io = split_bio_end;
1581                                 submit_bio(cloned_bio->bi_rw, cloned_bio);
1582                         }
1583                         /*
1584                          * Now we have to wait for all those smaller bios to
1585                          * end, so we can also end the "parent" bio.
1586                          */
1587                         continue;
1588                 }
1589                 /* We don't need to split this bio */
1590                 submit_bio(bio->bi_rw, bio);
1591         }
1592
1593         return 0;
1594 }
1595
1596 /**
1597  * We are reconnecting to the backend, due to a suspend/resume, or a backend
1598  * driver restart.  We tear down our blkif structure and recreate it, but
1599  * leave the device-layer structures intact so that this is transparent to the
1600  * rest of the kernel.
1601  */
1602 static int blkfront_resume(struct xenbus_device *dev)
1603 {
1604         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1605         int err;
1606
1607         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
1608
1609         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
1610
1611         err = talk_to_blkback(dev, info);
1612
1613         /*
1614          * We have to wait for the backend to switch to
1615          * connected state, since we want to read which
1616          * features it supports.
1617          */
1618
1619         return err;
1620 }
1621
1622 static void
1623 blkfront_closing(struct blkfront_info *info)
1624 {
1625         struct xenbus_device *xbdev = info->xbdev;
1626         struct block_device *bdev = NULL;
1627
1628         mutex_lock(&info->mutex);
1629
1630         if (xbdev->state == XenbusStateClosing) {
1631                 mutex_unlock(&info->mutex);
1632                 return;
1633         }
1634
1635         if (info->gd)
1636                 bdev = bdget_disk(info->gd, 0);
1637
1638         mutex_unlock(&info->mutex);
1639
1640         if (!bdev) {
1641                 xenbus_frontend_closed(xbdev);
1642                 return;
1643         }
1644
1645         mutex_lock(&bdev->bd_mutex);
1646
1647         if (bdev->bd_openers) {
1648                 xenbus_dev_error(xbdev, -EBUSY,
1649                                  "Device in use; refusing to close");
1650                 xenbus_switch_state(xbdev, XenbusStateClosing);
1651         } else {
1652                 xlvbd_release_gendisk(info);
1653                 xenbus_frontend_closed(xbdev);
1654         }
1655
1656         mutex_unlock(&bdev->bd_mutex);
1657         bdput(bdev);
1658 }
1659
1660 static void blkfront_setup_discard(struct blkfront_info *info)
1661 {
1662         int err;
1663         unsigned int discard_granularity;
1664         unsigned int discard_alignment;
1665         unsigned int discard_secure;
1666
1667         info->feature_discard = 1;
1668         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1669                 "discard-granularity", "%u", &discard_granularity,
1670                 "discard-alignment", "%u", &discard_alignment,
1671                 NULL);
1672         if (!err) {
1673                 info->discard_granularity = discard_granularity;
1674                 info->discard_alignment = discard_alignment;
1675         }
1676         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1677                     "discard-secure", "%d", &discard_secure,
1678                     NULL);
1679         if (!err)
1680                 info->feature_secdiscard = !!discard_secure;
1681 }
1682
1683 static int blkfront_setup_indirect(struct blkfront_info *info)
1684 {
1685         unsigned int indirect_segments, segs;
1686         int err, i;
1687
1688         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1689                             "feature-max-indirect-segments", "%u", &indirect_segments,
1690                             NULL);
1691         if (err) {
1692                 info->max_indirect_segments = 0;
1693                 segs = BLKIF_MAX_SEGMENTS_PER_REQUEST;
1694         } else {
1695                 info->max_indirect_segments = min(indirect_segments,
1696                                                   xen_blkif_max_segments);
1697                 segs = info->max_indirect_segments;
1698         }
1699
1700         err = fill_grant_buffer(info, (segs + INDIRECT_GREFS(segs)) * BLK_RING_SIZE);
1701         if (err)
1702                 goto out_of_memory;
1703
1704         if (!info->feature_persistent && info->max_indirect_segments) {
1705                 /*
1706                  * We are using indirect descriptors but not persistent
1707                  * grants, we need to allocate a set of pages that can be
1708                  * used for mapping indirect grefs
1709                  */
1710                 int num = INDIRECT_GREFS(segs) * BLK_RING_SIZE;
1711
1712                 BUG_ON(!list_empty(&info->indirect_pages));
1713                 for (i = 0; i < num; i++) {
1714                         struct page *indirect_page = alloc_page(GFP_NOIO);
1715                         if (!indirect_page)
1716                                 goto out_of_memory;
1717                         list_add(&indirect_page->lru, &info->indirect_pages);
1718                 }
1719         }
1720
1721         for (i = 0; i < BLK_RING_SIZE; i++) {
1722                 info->shadow[i].grants_used = kzalloc(
1723                         sizeof(info->shadow[i].grants_used[0]) * segs,
1724                         GFP_NOIO);
1725                 info->shadow[i].sg = kzalloc(sizeof(info->shadow[i].sg[0]) * segs, GFP_NOIO);
1726                 if (info->max_indirect_segments)
1727                         info->shadow[i].indirect_grants = kzalloc(
1728                                 sizeof(info->shadow[i].indirect_grants[0]) *
1729                                 INDIRECT_GREFS(segs),
1730                                 GFP_NOIO);
1731                 if ((info->shadow[i].grants_used == NULL) ||
1732                         (info->shadow[i].sg == NULL) ||
1733                      (info->max_indirect_segments &&
1734                      (info->shadow[i].indirect_grants == NULL)))
1735                         goto out_of_memory;
1736                 sg_init_table(info->shadow[i].sg, segs);
1737         }
1738
1739
1740         return 0;
1741
1742 out_of_memory:
1743         for (i = 0; i < BLK_RING_SIZE; i++) {
1744                 kfree(info->shadow[i].grants_used);
1745                 info->shadow[i].grants_used = NULL;
1746                 kfree(info->shadow[i].sg);
1747                 info->shadow[i].sg = NULL;
1748                 kfree(info->shadow[i].indirect_grants);
1749                 info->shadow[i].indirect_grants = NULL;
1750         }
1751         if (!list_empty(&info->indirect_pages)) {
1752                 struct page *indirect_page, *n;
1753                 list_for_each_entry_safe(indirect_page, n, &info->indirect_pages, lru) {
1754                         list_del(&indirect_page->lru);
1755                         __free_page(indirect_page);
1756                 }
1757         }
1758         return -ENOMEM;
1759 }
1760
1761 /*
1762  * Invoked when the backend is finally 'ready' (and has told produced
1763  * the details about the physical device - #sectors, size, etc).
1764  */
1765 static void blkfront_connect(struct blkfront_info *info)
1766 {
1767         unsigned long long sectors;
1768         unsigned long sector_size;
1769         unsigned int physical_sector_size;
1770         unsigned int binfo;
1771         int err;
1772         int barrier, flush, discard, persistent;
1773
1774         switch (info->connected) {
1775         case BLKIF_STATE_CONNECTED:
1776                 /*
1777                  * Potentially, the back-end may be signalling
1778                  * a capacity change; update the capacity.
1779                  */
1780                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1781                                    "sectors", "%Lu", &sectors);
1782                 if (XENBUS_EXIST_ERR(err))
1783                         return;
1784                 printk(KERN_INFO "Setting capacity to %Lu\n",
1785                        sectors);
1786                 set_capacity(info->gd, sectors);
1787                 revalidate_disk(info->gd);
1788
1789                 return;
1790         case BLKIF_STATE_SUSPENDED:
1791                 /*
1792                  * If we are recovering from suspension, we need to wait
1793                  * for the backend to announce it's features before
1794                  * reconnecting, at least we need to know if the backend
1795                  * supports indirect descriptors, and how many.
1796                  */
1797                 blkif_recover(info);
1798                 return;
1799
1800         default:
1801                 break;
1802         }
1803
1804         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
1805                 __func__, info->xbdev->otherend);
1806
1807         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1808                             "sectors", "%llu", &sectors,
1809                             "info", "%u", &binfo,
1810                             "sector-size", "%lu", &sector_size,
1811                             NULL);
1812         if (err) {
1813                 xenbus_dev_fatal(info->xbdev, err,
1814                                  "reading backend fields at %s",
1815                                  info->xbdev->otherend);
1816                 return;
1817         }
1818
1819         /*
1820          * physcial-sector-size is a newer field, so old backends may not
1821          * provide this. Assume physical sector size to be the same as
1822          * sector_size in that case.
1823          */
1824         err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1825                            "physical-sector-size", "%u", &physical_sector_size);
1826         if (err != 1)
1827                 physical_sector_size = sector_size;
1828
1829         info->feature_flush = 0;
1830
1831         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1832                             "feature-barrier", "%d", &barrier,
1833                             NULL);
1834
1835         /*
1836          * If there's no "feature-barrier" defined, then it means
1837          * we're dealing with a very old backend which writes
1838          * synchronously; nothing to do.
1839          *
1840          * If there are barriers, then we use flush.
1841          */
1842         if (!err && barrier)
1843                 info->feature_flush = REQ_FLUSH | REQ_FUA;
1844         /*
1845          * And if there is "feature-flush-cache" use that above
1846          * barriers.
1847          */
1848         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1849                             "feature-flush-cache", "%d", &flush,
1850                             NULL);
1851
1852         if (!err && flush)
1853                 info->feature_flush = REQ_FLUSH;
1854
1855         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1856                             "feature-discard", "%d", &discard,
1857                             NULL);
1858
1859         if (!err && discard)
1860                 blkfront_setup_discard(info);
1861
1862         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
1863                             "feature-persistent", "%u", &persistent,
1864                             NULL);
1865         if (err)
1866                 info->feature_persistent = 0;
1867         else
1868                 info->feature_persistent = persistent;
1869
1870         err = blkfront_setup_indirect(info);
1871         if (err) {
1872                 xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
1873                                  info->xbdev->otherend);
1874                 return;
1875         }
1876
1877         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
1878                                   physical_sector_size);
1879         if (err) {
1880                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
1881                                  info->xbdev->otherend);
1882                 return;
1883         }
1884
1885         xenbus_switch_state(info->xbdev, XenbusStateConnected);
1886
1887         /* Kick pending requests. */
1888         spin_lock_irq(&info->io_lock);
1889         info->connected = BLKIF_STATE_CONNECTED;
1890         kick_pending_request_queues(info);
1891         spin_unlock_irq(&info->io_lock);
1892
1893         add_disk(info->gd);
1894
1895         info->is_ready = 1;
1896 }
1897
1898 /**
1899  * Callback received when the backend's state changes.
1900  */
1901 static void blkback_changed(struct xenbus_device *dev,
1902                             enum xenbus_state backend_state)
1903 {
1904         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1905
1906         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
1907
1908         switch (backend_state) {
1909         case XenbusStateInitialising:
1910         case XenbusStateInitWait:
1911         case XenbusStateInitialised:
1912         case XenbusStateReconfiguring:
1913         case XenbusStateReconfigured:
1914         case XenbusStateUnknown:
1915                 break;
1916
1917         case XenbusStateConnected:
1918                 blkfront_connect(info);
1919                 break;
1920
1921         case XenbusStateClosed:
1922                 if (dev->state == XenbusStateClosed)
1923                         break;
1924                 /* Missed the backend's Closing state -- fallthrough */
1925         case XenbusStateClosing:
1926                 blkfront_closing(info);
1927                 break;
1928         }
1929 }
1930
1931 static int blkfront_remove(struct xenbus_device *xbdev)
1932 {
1933         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
1934         struct block_device *bdev = NULL;
1935         struct gendisk *disk;
1936
1937         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
1938
1939         blkif_free(info, 0);
1940
1941         mutex_lock(&info->mutex);
1942
1943         disk = info->gd;
1944         if (disk)
1945                 bdev = bdget_disk(disk, 0);
1946
1947         info->xbdev = NULL;
1948         mutex_unlock(&info->mutex);
1949
1950         if (!bdev) {
1951                 kfree(info);
1952                 return 0;
1953         }
1954
1955         /*
1956          * The xbdev was removed before we reached the Closed
1957          * state. See if it's safe to remove the disk. If the bdev
1958          * isn't closed yet, we let release take care of it.
1959          */
1960
1961         mutex_lock(&bdev->bd_mutex);
1962         info = disk->private_data;
1963
1964         dev_warn(disk_to_dev(disk),
1965                  "%s was hot-unplugged, %d stale handles\n",
1966                  xbdev->nodename, bdev->bd_openers);
1967
1968         if (info && !bdev->bd_openers) {
1969                 xlvbd_release_gendisk(info);
1970                 disk->private_data = NULL;
1971                 kfree(info);
1972         }
1973
1974         mutex_unlock(&bdev->bd_mutex);
1975         bdput(bdev);
1976
1977         return 0;
1978 }
1979
1980 static int blkfront_is_ready(struct xenbus_device *dev)
1981 {
1982         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
1983
1984         return info->is_ready && info->xbdev;
1985 }
1986
1987 static int blkif_open(struct block_device *bdev, fmode_t mode)
1988 {
1989         struct gendisk *disk = bdev->bd_disk;
1990         struct blkfront_info *info;
1991         int err = 0;
1992
1993         mutex_lock(&blkfront_mutex);
1994
1995         info = disk->private_data;
1996         if (!info) {
1997                 /* xbdev gone */
1998                 err = -ERESTARTSYS;
1999                 goto out;
2000         }
2001
2002         mutex_lock(&info->mutex);
2003
2004         if (!info->gd)
2005                 /* xbdev is closed */
2006                 err = -ERESTARTSYS;
2007
2008         mutex_unlock(&info->mutex);
2009
2010 out:
2011         mutex_unlock(&blkfront_mutex);
2012         return err;
2013 }
2014
2015 static void blkif_release(struct gendisk *disk, fmode_t mode)
2016 {
2017         struct blkfront_info *info = disk->private_data;
2018         struct block_device *bdev;
2019         struct xenbus_device *xbdev;
2020
2021         mutex_lock(&blkfront_mutex);
2022
2023         bdev = bdget_disk(disk, 0);
2024
2025         if (!bdev) {
2026                 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2027                 goto out_mutex;
2028         }
2029         if (bdev->bd_openers)
2030                 goto out;
2031
2032         /*
2033          * Check if we have been instructed to close. We will have
2034          * deferred this request, because the bdev was still open.
2035          */
2036
2037         mutex_lock(&info->mutex);
2038         xbdev = info->xbdev;
2039
2040         if (xbdev && xbdev->state == XenbusStateClosing) {
2041                 /* pending switch to state closed */
2042                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2043                 xlvbd_release_gendisk(info);
2044                 xenbus_frontend_closed(info->xbdev);
2045         }
2046
2047         mutex_unlock(&info->mutex);
2048
2049         if (!xbdev) {
2050                 /* sudden device removal */
2051                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2052                 xlvbd_release_gendisk(info);
2053                 disk->private_data = NULL;
2054                 kfree(info);
2055         }
2056
2057 out:
2058         bdput(bdev);
2059 out_mutex:
2060         mutex_unlock(&blkfront_mutex);
2061 }
2062
2063 static const struct block_device_operations xlvbd_block_fops =
2064 {
2065         .owner = THIS_MODULE,
2066         .open = blkif_open,
2067         .release = blkif_release,
2068         .getgeo = blkif_getgeo,
2069         .ioctl = blkif_ioctl,
2070 };
2071
2072
2073 static const struct xenbus_device_id blkfront_ids[] = {
2074         { "vbd" },
2075         { "" }
2076 };
2077
2078 static struct xenbus_driver blkfront_driver = {
2079         .ids  = blkfront_ids,
2080         .probe = blkfront_probe,
2081         .remove = blkfront_remove,
2082         .resume = blkfront_resume,
2083         .otherend_changed = blkback_changed,
2084         .is_ready = blkfront_is_ready,
2085 };
2086
2087 static int __init xlblk_init(void)
2088 {
2089         int ret;
2090
2091         if (!xen_domain())
2092                 return -ENODEV;
2093
2094         if (!xen_has_pv_disk_devices())
2095                 return -ENODEV;
2096
2097         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2098                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2099                        XENVBD_MAJOR, DEV_NAME);
2100                 return -ENODEV;
2101         }
2102
2103         ret = xenbus_register_frontend(&blkfront_driver);
2104         if (ret) {
2105                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2106                 return ret;
2107         }
2108
2109         return 0;
2110 }
2111 module_init(xlblk_init);
2112
2113
2114 static void __exit xlblk_exit(void)
2115 {
2116         xenbus_unregister_driver(&blkfront_driver);
2117         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2118         kfree(minors);
2119 }
2120 module_exit(xlblk_exit);
2121
2122 MODULE_DESCRIPTION("Xen virtual block device frontend");
2123 MODULE_LICENSE("GPL");
2124 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2125 MODULE_ALIAS("xen:vbd");
2126 MODULE_ALIAS("xenblk");