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/blk-mq.h>
  41 #include <linux/hdreg.h>
  42 #include <linux/cdrom.h>
  43 #include <linux/module.h>
  44 #include <linux/slab.h>
  45 #include <linux/mutex.h>
  46 #include <linux/scatterlist.h>
  47 #include <linux/bitmap.h>
  48 #include <linux/list.h>
  49
  50 #include <xen/xen.h>
  51 #include <xen/xenbus.h>
  52 #include <xen/grant_table.h>
  53 #include <xen/events.h>
  54 #include <xen/page.h>
  55 #include <xen/platform_pci.h>
  56
  57 #include <xen/interface/grant_table.h>
  58 #include <xen/interface/io/blkif.h>
  59 #include <xen/interface/io/protocols.h>
  60
  61 #include <asm/xen/hypervisor.h>
  62
  63 /*
  64  * The minimal size of segment supported by the block framework is PAGE_SIZE.
  65  * When Linux is using a different page size than Xen, it may not be possible
  66  * to put all the data in a single segment.
  67  * This can happen when the backend doesn't support indirect descriptor and
  68  * therefore the maximum amount of data that a request can carry is
  69  * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
  70  *
  71  * Note that we only support one extra request. So the Linux page size
  72  * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
  73  * 88KB.
  74  */
  75 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
  76
  77 enum blkif_state {
  78         BLKIF_STATE_DISCONNECTED,
  79         BLKIF_STATE_CONNECTED,
  80         BLKIF_STATE_SUSPENDED,
  81 };
  82
  83 struct grant {
  84         grant_ref_t gref;
  85         struct page *page;
  86         struct list_head node;
  87 };
  88
  89 enum blk_req_status {
  90         REQ_WAITING,
  91         REQ_DONE,
  92         REQ_ERROR,
  93         REQ_EOPNOTSUPP,
  94 };
  95
  96 struct blk_shadow {
  97         struct blkif_request req;
  98         struct request *request;
  99         struct grant **grants_used;
 100         struct grant **indirect_grants;
 101         struct scatterlist *sg;
 102         unsigned int num_sg;
 103         enum blk_req_status status;
 104
 105         #define NO_ASSOCIATED_ID ~0UL
 106         /*
 107          * Id of the sibling if we ever need 2 requests when handling a
 108          * block I/O request
 109          */
 110         unsigned long associated_id;
 111 };
 112
 113 struct split_bio {
 114         struct bio *bio;
 115         atomic_t pending;
 116 };
 117
 118 static DEFINE_MUTEX(blkfront_mutex);
 119 static const struct block_device_operations xlvbd_block_fops;
 120
 121 /*
 122  * Maximum number of segments in indirect requests, the actual value used by
 123  * the frontend driver is the minimum of this value and the value provided
 124  * by the backend driver.
 125  */
 126
 127 static unsigned int xen_blkif_max_segments = 32;
 128 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint,
 129                    S_IRUGO);
 130 MODULE_PARM_DESC(max_indirect_segments,
 131                  "Maximum amount of segments in indirect requests (default is 32)");
 132
 133 static unsigned int xen_blkif_max_queues = 4;
 134 module_param_named(max_queues, xen_blkif_max_queues, uint, S_IRUGO);
 135 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
 136
 137 /*
 138  * Maximum order of pages to be used for the shared ring between front and
 139  * backend, 4KB page granularity is used.
 140  */
 141 static unsigned int xen_blkif_max_ring_order;
 142 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO);
 143 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
 144
 145 #define BLK_RING_SIZE(info)     \
 146         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
 147
 148 #define BLK_MAX_RING_SIZE       \
 149         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS)
 150
 151 /*
 152  * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
 153  * characters are enough. Define to 20 to keep consistent with backend.
 154  */
 155 #define RINGREF_NAME_LEN (20)
 156 /*
 157  * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
 158  */
 159 #define QUEUE_NAME_LEN (17)
 160
 161 /*
 162  *  Per-ring info.
 163  *  Every blkfront device can associate with one or more blkfront_ring_info,
 164  *  depending on how many hardware queues/rings to be used.
 165  */
 166 struct blkfront_ring_info {
 167         /* Lock to protect data in every ring buffer. */
 168         spinlock_t ring_lock;
 169         struct blkif_front_ring ring;
 170         unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
 171         unsigned int evtchn, irq;
 172         struct work_struct work;
 173         struct gnttab_free_callback callback;
 174         struct blk_shadow shadow[BLK_MAX_RING_SIZE];
 175         struct list_head indirect_pages;
 176         struct list_head grants;
 177         unsigned int persistent_gnts_c;
 178         unsigned long shadow_free;
 179         struct blkfront_info *dev_info;
 180 };
 181
 182 /*
 183  * We have one of these per vbd, whether ide, scsi or 'other'.  They
 184  * hang in private_data off the gendisk structure. We may end up
 185  * putting all kinds of interesting stuff here :-)
 186  */
 187 struct blkfront_info
 188 {
 189         struct mutex mutex;
 190         struct xenbus_device *xbdev;
 191         struct gendisk *gd;
 192         int vdevice;
 193         blkif_vdev_t handle;
 194         enum blkif_state connected;
 195         /* Number of pages per ring buffer. */
 196         unsigned int nr_ring_pages;
 197         struct request_queue *rq;
 198         unsigned int feature_flush;
 199         unsigned int feature_discard:1;
 200         unsigned int feature_secdiscard:1;
 201         unsigned int discard_granularity;
 202         unsigned int discard_alignment;
 203         unsigned int feature_persistent:1;
 204         /* Number of 4KB segments handled */
 205         unsigned int max_indirect_segments;
 206         int is_ready;
 207         struct blk_mq_tag_set tag_set;
 208         struct blkfront_ring_info *rinfo;
 209         unsigned int nr_rings;
 210         /* Save uncomplete reqs and bios for migration. */
 211         struct list_head requests;
 212         struct bio_list bio_list;
 213 };
 214
 215 static unsigned int nr_minors;
 216 static unsigned long *minors;
 217 static DEFINE_SPINLOCK(minor_lock);
 218
 219 #define GRANT_INVALID_REF       0
 220
 221 #define PARTS_PER_DISK          16
 222 #define PARTS_PER_EXT_DISK      256
 223
 224 #define BLKIF_MAJOR(dev) ((dev)>>8)
 225 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 226
 227 #define EXT_SHIFT 28
 228 #define EXTENDED (1<<EXT_SHIFT)
 229 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 230 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 231 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 232 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 233 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 234 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 235
 236 #define DEV_NAME        "xvd"   /* name in /dev */
 237
 238 /*
 239  * Grants are always the same size as a Xen page (i.e 4KB).
 240  * A physical segment is always the same size as a Linux page.
 241  * Number of grants per physical segment
 242  */
 243 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
 244
 245 #define GRANTS_PER_INDIRECT_FRAME \
 246         (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
 247
 248 #define PSEGS_PER_INDIRECT_FRAME        \
 249         (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS)
 250
 251 #define INDIRECT_GREFS(_grants)         \
 252         DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
 253
 254 #define GREFS(_psegs)   ((_psegs) * GRANTS_PER_PSEG)
 255
 256 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 257 static void blkfront_gather_backend_features(struct blkfront_info *info);
 258
 259 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 260 {
 261         unsigned long free = rinfo->shadow_free;
 262
 263         BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
 264         rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
 265         rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 266         return free;
 267 }
 268
 269 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
 270                               unsigned long id)
 271 {
 272         if (rinfo->shadow[id].req.u.rw.id != id)
 273                 return -EINVAL;
 274         if (rinfo->shadow[id].request == NULL)
 275                 return -EINVAL;
 276         rinfo->shadow[id].req.u.rw.id  = rinfo->shadow_free;
 277         rinfo->shadow[id].request = NULL;
 278         rinfo->shadow_free = id;
 279         return 0;
 280 }
 281
 282 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 283 {
 284         struct blkfront_info *info = rinfo->dev_info;
 285         struct page *granted_page;
 286         struct grant *gnt_list_entry, *n;
 287         int i = 0;
 288
 289         while (i < num) {
 290                 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
 291                 if (!gnt_list_entry)
 292                         goto out_of_memory;
 293
 294                 if (info->feature_persistent) {
 295                         granted_page = alloc_page(GFP_NOIO);
 296                         if (!granted_page) {
 297                                 kfree(gnt_list_entry);
 298                                 goto out_of_memory;
 299                         }
 300                         gnt_list_entry->page = granted_page;
 301                 }
 302
 303                 gnt_list_entry->gref = GRANT_INVALID_REF;
 304                 list_add(&gnt_list_entry->node, &rinfo->grants);
 305                 i++;
 306         }
 307
 308         return 0;
 309
 310 out_of_memory:
 311         list_for_each_entry_safe(gnt_list_entry, n,
 312                                  &rinfo->grants, node) {
 313                 list_del(&gnt_list_entry->node);
 314                 if (info->feature_persistent)
 315                         __free_page(gnt_list_entry->page);
 316                 kfree(gnt_list_entry);
 317                 i--;
 318         }
 319         BUG_ON(i != 0);
 320         return -ENOMEM;
 321 }
 322
 323 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
 324 {
 325         struct grant *gnt_list_entry;
 326
 327         BUG_ON(list_empty(&rinfo->grants));
 328         gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
 329                                           node);
 330         list_del(&gnt_list_entry->node);
 331
 332         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 333                 rinfo->persistent_gnts_c--;
 334
 335         return gnt_list_entry;
 336 }
 337
 338 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
 339                                         const struct blkfront_info *info)
 340 {
 341         gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
 342                                                  info->xbdev->otherend_id,
 343                                                  gnt_list_entry->page,
 344                                                  0);
 345 }
 346
 347 static struct grant *get_grant(grant_ref_t *gref_head,
 348                                unsigned long gfn,
 349                                struct blkfront_ring_info *rinfo)
 350 {
 351         struct grant *gnt_list_entry = get_free_grant(rinfo);
 352         struct blkfront_info *info = rinfo->dev_info;
 353
 354         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 355                 return gnt_list_entry;
 356
 357         /* Assign a gref to this page */
 358         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 359         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 360         if (info->feature_persistent)
 361                 grant_foreign_access(gnt_list_entry, info);
 362         else {
 363                 /* Grant access to the GFN passed by the caller */
 364                 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
 365                                                 info->xbdev->otherend_id,
 366                                                 gfn, 0);
 367         }
 368
 369         return gnt_list_entry;
 370 }
 371
 372 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
 373                                         struct blkfront_ring_info *rinfo)
 374 {
 375         struct grant *gnt_list_entry = get_free_grant(rinfo);
 376         struct blkfront_info *info = rinfo->dev_info;
 377
 378         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 379                 return gnt_list_entry;
 380
 381         /* Assign a gref to this page */
 382         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 383         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 384         if (!info->feature_persistent) {
 385                 struct page *indirect_page;
 386
 387                 /* Fetch a pre-allocated page to use for indirect grefs */
 388                 BUG_ON(list_empty(&rinfo->indirect_pages));
 389                 indirect_page = list_first_entry(&rinfo->indirect_pages,
 390                                                  struct page, lru);
 391                 list_del(&indirect_page->lru);
 392                 gnt_list_entry->page = indirect_page;
 393         }
 394         grant_foreign_access(gnt_list_entry, info);
 395
 396         return gnt_list_entry;
 397 }
 398
 399 static const char *op_name(int op)
 400 {
 401         static const char *const names[] = {
 402                 [BLKIF_OP_READ] = "read",
 403                 [BLKIF_OP_WRITE] = "write",
 404                 [BLKIF_OP_WRITE_BARRIER] = "barrier",
 405                 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
 406                 [BLKIF_OP_DISCARD] = "discard" };
 407
 408         if (op < 0 || op >= ARRAY_SIZE(names))
 409                 return "unknown";
 410
 411         if (!names[op])
 412                 return "reserved";
 413
 414         return names[op];
 415 }
 416 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 417 {
 418         unsigned int end = minor + nr;
 419         int rc;
 420
 421         if (end > nr_minors) {
 422                 unsigned long *bitmap, *old;
 423
 424                 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 425                                  GFP_KERNEL);
 426                 if (bitmap == NULL)
 427                         return -ENOMEM;
 428
 429                 spin_lock(&minor_lock);
 430                 if (end > nr_minors) {
 431                         old = minors;
 432                         memcpy(bitmap, minors,
 433                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 434                         minors = bitmap;
 435                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 436                 } else
 437                         old = bitmap;
 438                 spin_unlock(&minor_lock);
 439                 kfree(old);
 440         }
 441
 442         spin_lock(&minor_lock);
 443         if (find_next_bit(minors, end, minor) >= end) {
 444                 bitmap_set(minors, minor, nr);
 445                 rc = 0;
 446         } else
 447                 rc = -EBUSY;
 448         spin_unlock(&minor_lock);
 449
 450         return rc;
 451 }
 452
 453 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 454 {
 455         unsigned int end = minor + nr;
 456
 457         BUG_ON(end > nr_minors);
 458         spin_lock(&minor_lock);
 459         bitmap_clear(minors,  minor, nr);
 460         spin_unlock(&minor_lock);
 461 }
 462
 463 static void blkif_restart_queue_callback(void *arg)
 464 {
 465         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
 466         schedule_work(&rinfo->work);
 467 }
 468
 469 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 470 {
 471         /* We don't have real geometry info, but let's at least return
 472            values consistent with the size of the device */
 473         sector_t nsect = get_capacity(bd->bd_disk);
 474         sector_t cylinders = nsect;
 475
 476         hg->heads = 0xff;
 477         hg->sectors = 0x3f;
 478         sector_div(cylinders, hg->heads * hg->sectors);
 479         hg->cylinders = cylinders;
 480         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 481                 hg->cylinders = 0xffff;
 482         return 0;
 483 }
 484
 485 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 486                        unsigned command, unsigned long argument)
 487 {
 488         struct blkfront_info *info = bdev->bd_disk->private_data;
 489         int i;
 490
 491         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 492                 command, (long)argument);
 493
 494         switch (command) {
 495         case CDROMMULTISESSION:
 496                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 497                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 498                         if (put_user(0, (char __user *)(argument + i)))
 499                                 return -EFAULT;
 500                 return 0;
 501
 502         case CDROM_GET_CAPABILITY: {
 503                 struct gendisk *gd = info->gd;
 504                 if (gd->flags & GENHD_FL_CD)
 505                         return 0;
 506                 return -EINVAL;
 507         }
 508
 509         default:
 510                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 511                   command);*/
 512                 return -EINVAL; /* same return as native Linux */
 513         }
 514
 515         return 0;
 516 }
 517
 518 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 519                                             struct request *req,
 520                                             struct blkif_request **ring_req)
 521 {
 522         unsigned long id;
 523
 524         *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
 525         rinfo->ring.req_prod_pvt++;
 526
 527         id = get_id_from_freelist(rinfo);
 528         rinfo->shadow[id].request = req;
 529         rinfo->shadow[id].status = REQ_WAITING;
 530         rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
 531
 532         (*ring_req)->u.rw.id = id;
 533
 534         return id;
 535 }
 536
 537 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
 538 {
 539         struct blkfront_info *info = rinfo->dev_info;
 540         struct blkif_request *ring_req;
 541         unsigned long id;
 542
 543         /* Fill out a communications ring structure. */
 544         id = blkif_ring_get_request(rinfo, req, &ring_req);
 545
 546         ring_req->operation = BLKIF_OP_DISCARD;
 547         ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
 548         ring_req->u.discard.id = id;
 549         ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
 550         if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
 551                 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
 552         else
 553                 ring_req->u.discard.flag = 0;
 554
 555         /* Keep a private copy so we can reissue requests when recovering. */
 556         rinfo->shadow[id].req = *ring_req;
 557
 558         return 0;
 559 }
 560
 561 struct setup_rw_req {
 562         unsigned int grant_idx;
 563         struct blkif_request_segment *segments;
 564         struct blkfront_ring_info *rinfo;
 565         struct blkif_request *ring_req;
 566         grant_ref_t gref_head;
 567         unsigned int id;
 568         /* Only used when persistent grant is used and it's a read request */
 569         bool need_copy;
 570         unsigned int bvec_off;
 571         char *bvec_data;
 572
 573         bool require_extra_req;
 574         struct blkif_request *extra_ring_req;
 575 };
 576
 577 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
 578                                      unsigned int len, void *data)
 579 {
 580         struct setup_rw_req *setup = data;
 581         int n, ref;
 582         struct grant *gnt_list_entry;
 583         unsigned int fsect, lsect;
 584         /* Convenient aliases */
 585         unsigned int grant_idx = setup->grant_idx;
 586         struct blkif_request *ring_req = setup->ring_req;
 587         struct blkfront_ring_info *rinfo = setup->rinfo;
 588         /*
 589          * We always use the shadow of the first request to store the list
 590          * of grant associated to the block I/O request. This made the
 591          * completion more easy to handle even if the block I/O request is
 592          * split.
 593          */
 594         struct blk_shadow *shadow = &rinfo->shadow[setup->id];
 595
 596         if (unlikely(setup->require_extra_req &&
 597                      grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
 598                 /*
 599                  * We are using the second request, setup grant_idx
 600                  * to be the index of the segment array.
 601                  */
 602                 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
 603                 ring_req = setup->extra_ring_req;
 604         }
 605
 606         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 607             (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
 608                 if (setup->segments)
 609                         kunmap_atomic(setup->segments);
 610
 611                 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
 612                 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
 613                 shadow->indirect_grants[n] = gnt_list_entry;
 614                 setup->segments = kmap_atomic(gnt_list_entry->page);
 615                 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 616         }
 617
 618         gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
 619         ref = gnt_list_entry->gref;
 620         /*
 621          * All the grants are stored in the shadow of the first
 622          * request. Therefore we have to use the global index.
 623          */
 624         shadow->grants_used[setup->grant_idx] = gnt_list_entry;
 625
 626         if (setup->need_copy) {
 627                 void *shared_data;
 628
 629                 shared_data = kmap_atomic(gnt_list_entry->page);
 630                 /*
 631                  * this does not wipe data stored outside the
 632                  * range sg->offset..sg->offset+sg->length.
 633                  * Therefore, blkback *could* see data from
 634                  * previous requests. This is OK as long as
 635                  * persistent grants are shared with just one
 636                  * domain. It may need refactoring if this
 637                  * changes
 638                  */
 639                 memcpy(shared_data + offset,
 640                        setup->bvec_data + setup->bvec_off,
 641                        len);
 642
 643                 kunmap_atomic(shared_data);
 644                 setup->bvec_off += len;
 645         }
 646
 647         fsect = offset >> 9;
 648         lsect = fsect + (len >> 9) - 1;
 649         if (ring_req->operation != BLKIF_OP_INDIRECT) {
 650                 ring_req->u.rw.seg[grant_idx] =
 651                         (struct blkif_request_segment) {
 652                                 .gref       = ref,
 653                                 .first_sect = fsect,
 654                                 .last_sect  = lsect };
 655         } else {
 656                 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
 657                         (struct blkif_request_segment) {
 658                                 .gref       = ref,
 659                                 .first_sect = fsect,
 660                                 .last_sect  = lsect };
 661         }
 662
 663         (setup->grant_idx)++;
 664 }
 665
 666 static void blkif_setup_extra_req(struct blkif_request *first,
 667                                   struct blkif_request *second)
 668 {
 669         uint16_t nr_segments = first->u.rw.nr_segments;
 670
 671         /*
 672          * The second request is only present when the first request uses
 673          * all its segments. It's always the continuity of the first one.
 674          */
 675         first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 676
 677         second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
 678         second->u.rw.sector_number = first->u.rw.sector_number +
 679                 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
 680
 681         second->u.rw.handle = first->u.rw.handle;
 682         second->operation = first->operation;
 683 }
 684
 685 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
 686 {
 687         struct blkfront_info *info = rinfo->dev_info;
 688         struct blkif_request *ring_req, *extra_ring_req = NULL;
 689         unsigned long id, extra_id = NO_ASSOCIATED_ID;
 690         bool require_extra_req = false;
 691         int i;
 692         struct setup_rw_req setup = {
 693                 .grant_idx = 0,
 694                 .segments = NULL,
 695                 .rinfo = rinfo,
 696                 .need_copy = rq_data_dir(req) && info->feature_persistent,
 697         };
 698
 699         /*
 700          * Used to store if we are able to queue the request by just using
 701          * existing persistent grants, or if we have to get new grants,
 702          * as there are not sufficiently many free.
 703          */
 704         struct scatterlist *sg;
 705         int num_sg, max_grefs, num_grant;
 706
 707         max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
 708         if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
 709                 /*
 710                  * If we are using indirect segments we need to account
 711                  * for the indirect grefs used in the request.
 712                  */
 713                 max_grefs += INDIRECT_GREFS(max_grefs);
 714
 715         /*
 716          * We have to reserve 'max_grefs' grants because persistent
 717          * grants are shared by all rings.
 718          */
 719         if (max_grefs > 0)
 720                 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) {
 721                         gnttab_request_free_callback(
 722                                 &rinfo->callback,
 723                                 blkif_restart_queue_callback,
 724                                 rinfo,
 725                                 max_grefs);
 726                         return 1;
 727                 }
 728
 729         /* Fill out a communications ring structure. */
 730         id = blkif_ring_get_request(rinfo, req, &ring_req);
 731
 732         num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 733         num_grant = 0;
 734         /* Calculate the number of grant used */
 735         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
 736                num_grant += gnttab_count_grant(sg->offset, sg->length);
 737
 738         require_extra_req = info->max_indirect_segments == 0 &&
 739                 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
 740         BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
 741
 742         rinfo->shadow[id].num_sg = num_sg;
 743         if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
 744             likely(!require_extra_req)) {
 745                 /*
 746                  * The indirect operation can only be a BLKIF_OP_READ or
 747                  * BLKIF_OP_WRITE
 748                  */
 749                 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
 750                 ring_req->operation = BLKIF_OP_INDIRECT;
 751                 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
 752                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 753                 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
 754                 ring_req->u.indirect.handle = info->handle;
 755                 ring_req->u.indirect.nr_segments = num_grant;
 756         } else {
 757                 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 758                 ring_req->u.rw.handle = info->handle;
 759                 ring_req->operation = rq_data_dir(req) ?
 760                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 761                 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
 762                         /*
 763                          * Ideally we can do an unordered flush-to-disk.
 764                          * In case the backend onlysupports barriers, use that.
 765                          * A barrier request a superset of FUA, so we can
 766                          * implement it the same way.  (It's also a FLUSH+FUA,
 767                          * since it is guaranteed ordered WRT previous writes.)
 768                          */
 769                         switch (info->feature_flush &
 770                                 ((REQ_FLUSH|REQ_FUA))) {
 771                         case REQ_FLUSH|REQ_FUA:
 772                                 ring_req->operation =
 773                                         BLKIF_OP_WRITE_BARRIER;
 774                                 break;
 775                         case REQ_FLUSH:
 776                                 ring_req->operation =
 777                                         BLKIF_OP_FLUSH_DISKCACHE;
 778                                 break;
 779                         default:
 780                                 ring_req->operation = 0;
 781                         }
 782                 }
 783                 ring_req->u.rw.nr_segments = num_grant;
 784                 if (unlikely(require_extra_req)) {
 785                         extra_id = blkif_ring_get_request(rinfo, req,
 786                                                           &extra_ring_req);
 787                         /*
 788                          * Only the first request contains the scatter-gather
 789                          * list.
 790                          */
 791                         rinfo->shadow[extra_id].num_sg = 0;
 792
 793                         blkif_setup_extra_req(ring_req, extra_ring_req);
 794
 795                         /* Link the 2 requests together */
 796                         rinfo->shadow[extra_id].associated_id = id;
 797                         rinfo->shadow[id].associated_id = extra_id;
 798                 }
 799         }
 800
 801         setup.ring_req = ring_req;
 802         setup.id = id;
 803
 804         setup.require_extra_req = require_extra_req;
 805         if (unlikely(require_extra_req))
 806                 setup.extra_ring_req = extra_ring_req;
 807
 808         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
 809                 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
 810
 811                 if (setup.need_copy) {
 812                         setup.bvec_off = sg->offset;
 813                         setup.bvec_data = kmap_atomic(sg_page(sg));
 814                 }
 815
 816                 gnttab_foreach_grant_in_range(sg_page(sg),
 817                                               sg->offset,
 818                                               sg->length,
 819                                               blkif_setup_rw_req_grant,
 820                                               &setup);
 821
 822                 if (setup.need_copy)
 823                         kunmap_atomic(setup.bvec_data);
 824         }
 825         if (setup.segments)
 826                 kunmap_atomic(setup.segments);
 827
 828         /* Keep a private copy so we can reissue requests when recovering. */
 829         rinfo->shadow[id].req = *ring_req;
 830         if (unlikely(require_extra_req))
 831                 rinfo->shadow[extra_id].req = *extra_ring_req;
 832
 833         if (max_grefs > 0)
 834                 gnttab_free_grant_references(setup.gref_head);
 835
 836         return 0;
 837 }
 838
 839 /*
 840  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 841  * and writes are handled as expected.
 842  *
 843  * @req: a request struct
 844  */
 845 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
 846 {
 847         if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
 848                 return 1;
 849
 850         if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE)))
 851                 return blkif_queue_discard_req(req, rinfo);
 852         else
 853                 return blkif_queue_rw_req(req, rinfo);
 854 }
 855
 856 static inline void flush_requests(struct blkfront_ring_info *rinfo)
 857 {
 858         int notify;
 859
 860         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
 861
 862         if (notify)
 863                 notify_remote_via_irq(rinfo->irq);
 864 }
 865
 866 static inline bool blkif_request_flush_invalid(struct request *req,
 867                                                struct blkfront_info *info)
 868 {
 869         return ((req->cmd_type != REQ_TYPE_FS) ||
 870                 ((req->cmd_flags & REQ_FLUSH) &&
 871                  !(info->feature_flush & REQ_FLUSH)) ||
 872                 ((req->cmd_flags & REQ_FUA) &&
 873                  !(info->feature_flush & REQ_FUA)));
 874 }
 875
 876 static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
 877                           const struct blk_mq_queue_data *qd)
 878 {
 879         unsigned long flags;
 880         int qid = hctx->queue_num;
 881         struct blkfront_info *info = hctx->queue->queuedata;
 882         struct blkfront_ring_info *rinfo = NULL;
 883
 884         BUG_ON(info->nr_rings <= qid);
 885         rinfo = &info->rinfo[qid];
 886         blk_mq_start_request(qd->rq);
 887         spin_lock_irqsave(&rinfo->ring_lock, flags);
 888         if (RING_FULL(&rinfo->ring))
 889                 goto out_busy;
 890
 891         if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
 892                 goto out_err;
 893
 894         if (blkif_queue_request(qd->rq, rinfo))
 895                 goto out_busy;
 896
 897         flush_requests(rinfo);
 898         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 899         return BLK_MQ_RQ_QUEUE_OK;
 900
 901 out_err:
 902         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 903         return BLK_MQ_RQ_QUEUE_ERROR;
 904
 905 out_busy:
 906         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 907         blk_mq_stop_hw_queue(hctx);
 908         return BLK_MQ_RQ_QUEUE_BUSY;
 909 }
 910
 911 static struct blk_mq_ops blkfront_mq_ops = {
 912         .queue_rq = blkif_queue_rq,
 913         .map_queue = blk_mq_map_queue,
 914 };
 915
 916 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 917                                 unsigned int physical_sector_size,
 918                                 unsigned int segments)
 919 {
 920         struct request_queue *rq;
 921         struct blkfront_info *info = gd->private_data;
 922
 923         memset(&info->tag_set, 0, sizeof(info->tag_set));
 924         info->tag_set.ops = &blkfront_mq_ops;
 925         info->tag_set.nr_hw_queues = info->nr_rings;
 926         if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
 927                 /*
 928                  * When indirect descriptior is not supported, the I/O request
 929                  * will be split between multiple request in the ring.
 930                  * To avoid problems when sending the request, divide by
 931                  * 2 the depth of the queue.
 932                  */
 933                 info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
 934         } else
 935                 info->tag_set.queue_depth = BLK_RING_SIZE(info);
 936         info->tag_set.numa_node = NUMA_NO_NODE;
 937         info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
 938         info->tag_set.cmd_size = 0;
 939         info->tag_set.driver_data = info;
 940
 941         if (blk_mq_alloc_tag_set(&info->tag_set))
 942                 return -EINVAL;
 943         rq = blk_mq_init_queue(&info->tag_set);
 944         if (IS_ERR(rq)) {
 945                 blk_mq_free_tag_set(&info->tag_set);
 946                 return PTR_ERR(rq);
 947         }
 948
 949         rq->queuedata = info;
 950         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
 951
 952         if (info->feature_discard) {
 953                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
 954                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
 955                 rq->limits.discard_granularity = info->discard_granularity;
 956                 rq->limits.discard_alignment = info->discard_alignment;
 957                 if (info->feature_secdiscard)
 958                         queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
 959         }
 960
 961         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 962         blk_queue_logical_block_size(rq, sector_size);
 963         blk_queue_physical_block_size(rq, physical_sector_size);
 964         blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
 965
 966         /* Each segment in a request is up to an aligned page in size. */
 967         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 968         blk_queue_max_segment_size(rq, PAGE_SIZE);
 969
 970         /* Ensure a merged request will fit in a single I/O ring slot. */
 971         blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
 972
 973         /* Make sure buffer addresses are sector-aligned. */
 974         blk_queue_dma_alignment(rq, 511);
 975
 976         /* Make sure we don't use bounce buffers. */
 977         blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
 978
 979         gd->queue = rq;
 980
 981         return 0;
 982 }
 983
 984 static const char *flush_info(unsigned int feature_flush)
 985 {
 986         switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) {
 987         case REQ_FLUSH|REQ_FUA:
 988                 return "barrier: enabled;";
 989         case REQ_FLUSH:
 990                 return "flush diskcache: enabled;";
 991         default:
 992                 return "barrier or flush: disabled;";
 993         }
 994 }
 995
 996 static void xlvbd_flush(struct blkfront_info *info)
 997 {
 998         blk_queue_write_cache(info->rq, info->feature_flush & REQ_FLUSH,
 999                                 info->feature_flush & REQ_FUA);
1000         pr_info("blkfront: %s: %s %s %s %s %s\n",
1001                 info->gd->disk_name, flush_info(info->feature_flush),
1002                 "persistent grants:", info->feature_persistent ?
1003                 "enabled;" : "disabled;", "indirect descriptors:",
1004                 info->max_indirect_segments ? "enabled;" : "disabled;");
1005 }
1006
1007 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1008 {
1009         int major;
1010         major = BLKIF_MAJOR(vdevice);
1011         *minor = BLKIF_MINOR(vdevice);
1012         switch (major) {
1013                 case XEN_IDE0_MAJOR:
1014                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1015                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
1016                                 EMULATED_HD_DISK_MINOR_OFFSET;
1017                         break;
1018                 case XEN_IDE1_MAJOR:
1019                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1020                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1021                                 EMULATED_HD_DISK_MINOR_OFFSET;
1022                         break;
1023                 case XEN_SCSI_DISK0_MAJOR:
1024                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1025                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1026                         break;
1027                 case XEN_SCSI_DISK1_MAJOR:
1028                 case XEN_SCSI_DISK2_MAJOR:
1029                 case XEN_SCSI_DISK3_MAJOR:
1030                 case XEN_SCSI_DISK4_MAJOR:
1031                 case XEN_SCSI_DISK5_MAJOR:
1032                 case XEN_SCSI_DISK6_MAJOR:
1033                 case XEN_SCSI_DISK7_MAJOR:
1034                         *offset = (*minor / PARTS_PER_DISK) +
1035                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1036                                 EMULATED_SD_DISK_NAME_OFFSET;
1037                         *minor = *minor +
1038                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1039                                 EMULATED_SD_DISK_MINOR_OFFSET;
1040                         break;
1041                 case XEN_SCSI_DISK8_MAJOR:
1042                 case XEN_SCSI_DISK9_MAJOR:
1043                 case XEN_SCSI_DISK10_MAJOR:
1044                 case XEN_SCSI_DISK11_MAJOR:
1045                 case XEN_SCSI_DISK12_MAJOR:
1046                 case XEN_SCSI_DISK13_MAJOR:
1047                 case XEN_SCSI_DISK14_MAJOR:
1048                 case XEN_SCSI_DISK15_MAJOR:
1049                         *offset = (*minor / PARTS_PER_DISK) +
1050                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1051                                 EMULATED_SD_DISK_NAME_OFFSET;
1052                         *minor = *minor +
1053                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1054                                 EMULATED_SD_DISK_MINOR_OFFSET;
1055                         break;
1056                 case XENVBD_MAJOR:
1057                         *offset = *minor / PARTS_PER_DISK;
1058                         break;
1059                 default:
1060                         printk(KERN_WARNING "blkfront: your disk configuration is "
1061                                         "incorrect, please use an xvd device instead\n");
1062                         return -ENODEV;
1063         }
1064         return 0;
1065 }
1066
1067 static char *encode_disk_name(char *ptr, unsigned int n)
1068 {
1069         if (n >= 26)
1070                 ptr = encode_disk_name(ptr, n / 26 - 1);
1071         *ptr = 'a' + n % 26;
1072         return ptr + 1;
1073 }
1074
1075 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1076                                struct blkfront_info *info,
1077                                u16 vdisk_info, u16 sector_size,
1078                                unsigned int physical_sector_size)
1079 {
1080         struct gendisk *gd;
1081         int nr_minors = 1;
1082         int err;
1083         unsigned int offset;
1084         int minor;
1085         int nr_parts;
1086         char *ptr;
1087
1088         BUG_ON(info->gd != NULL);
1089         BUG_ON(info->rq != NULL);
1090
1091         if ((info->vdevice>>EXT_SHIFT) > 1) {
1092                 /* this is above the extended range; something is wrong */
1093                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1094                 return -ENODEV;
1095         }
1096
1097         if (!VDEV_IS_EXTENDED(info->vdevice)) {
1098                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1099                 if (err)
1100                         return err;
1101                 nr_parts = PARTS_PER_DISK;
1102         } else {
1103                 minor = BLKIF_MINOR_EXT(info->vdevice);
1104                 nr_parts = PARTS_PER_EXT_DISK;
1105                 offset = minor / nr_parts;
1106                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1107                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1108                                         "emulated IDE disks,\n\t choose an xvd device name"
1109                                         "from xvde on\n", info->vdevice);
1110         }
1111         if (minor >> MINORBITS) {
1112                 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1113                         info->vdevice, minor);
1114                 return -ENODEV;
1115         }
1116
1117         if ((minor % nr_parts) == 0)
1118                 nr_minors = nr_parts;
1119
1120         err = xlbd_reserve_minors(minor, nr_minors);
1121         if (err)
1122                 goto out;
1123         err = -ENODEV;
1124
1125         gd = alloc_disk(nr_minors);
1126         if (gd == NULL)
1127                 goto release;
1128
1129         strcpy(gd->disk_name, DEV_NAME);
1130         ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1131         BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1132         if (nr_minors > 1)
1133                 *ptr = 0;
1134         else
1135                 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1136                          "%d", minor & (nr_parts - 1));
1137
1138         gd->major = XENVBD_MAJOR;
1139         gd->first_minor = minor;
1140         gd->fops = &xlvbd_block_fops;
1141         gd->private_data = info;
1142         gd->driverfs_dev = &(info->xbdev->dev);
1143         set_capacity(gd, capacity);
1144
1145         if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
1146                                  info->max_indirect_segments ? :
1147                                  BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
1148                 del_gendisk(gd);
1149                 goto release;
1150         }
1151
1152         info->rq = gd->queue;
1153         info->gd = gd;
1154
1155         xlvbd_flush(info);
1156
1157         if (vdisk_info & VDISK_READONLY)
1158                 set_disk_ro(gd, 1);
1159
1160         if (vdisk_info & VDISK_REMOVABLE)
1161                 gd->flags |= GENHD_FL_REMOVABLE;
1162
1163         if (vdisk_info & VDISK_CDROM)
1164                 gd->flags |= GENHD_FL_CD;
1165
1166         return 0;
1167
1168  release:
1169         xlbd_release_minors(minor, nr_minors);
1170  out:
1171         return err;
1172 }
1173
1174 static void xlvbd_release_gendisk(struct blkfront_info *info)
1175 {
1176         unsigned int minor, nr_minors, i;
1177
1178         if (info->rq == NULL)
1179                 return;
1180
1181         /* No more blkif_request(). */
1182         blk_mq_stop_hw_queues(info->rq);
1183
1184         for (i = 0; i < info->nr_rings; i++) {
1185                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1186
1187                 /* No more gnttab callback work. */
1188                 gnttab_cancel_free_callback(&rinfo->callback);
1189
1190                 /* Flush gnttab callback work. Must be done with no locks held. */
1191                 flush_work(&rinfo->work);
1192         }
1193
1194         del_gendisk(info->gd);
1195
1196         minor = info->gd->first_minor;
1197         nr_minors = info->gd->minors;
1198         xlbd_release_minors(minor, nr_minors);
1199
1200         blk_cleanup_queue(info->rq);
1201         blk_mq_free_tag_set(&info->tag_set);
1202         info->rq = NULL;
1203
1204         put_disk(info->gd);
1205         info->gd = NULL;
1206 }
1207
1208 /* Already hold rinfo->ring_lock. */
1209 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1210 {
1211         if (!RING_FULL(&rinfo->ring))
1212                 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1213 }
1214
1215 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1216 {
1217         unsigned long flags;
1218
1219         spin_lock_irqsave(&rinfo->ring_lock, flags);
1220         kick_pending_request_queues_locked(rinfo);
1221         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1222 }
1223
1224 static void blkif_restart_queue(struct work_struct *work)
1225 {
1226         struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1227
1228         if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1229                 kick_pending_request_queues(rinfo);
1230 }
1231
1232 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1233 {
1234         struct grant *persistent_gnt, *n;
1235         struct blkfront_info *info = rinfo->dev_info;
1236         int i, j, segs;
1237
1238         /*
1239          * Remove indirect pages, this only happens when using indirect
1240          * descriptors but not persistent grants
1241          */
1242         if (!list_empty(&rinfo->indirect_pages)) {
1243                 struct page *indirect_page, *n;
1244
1245                 BUG_ON(info->feature_persistent);
1246                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1247                         list_del(&indirect_page->lru);
1248                         __free_page(indirect_page);
1249                 }
1250         }
1251
1252         /* Remove all persistent grants. */
1253         if (!list_empty(&rinfo->grants)) {
1254                 list_for_each_entry_safe(persistent_gnt, n,
1255                                          &rinfo->grants, node) {
1256                         list_del(&persistent_gnt->node);
1257                         if (persistent_gnt->gref != GRANT_INVALID_REF) {
1258                                 gnttab_end_foreign_access(persistent_gnt->gref,
1259                                                           0, 0UL);
1260                                 rinfo->persistent_gnts_c--;
1261                         }
1262                         if (info->feature_persistent)
1263                                 __free_page(persistent_gnt->page);
1264                         kfree(persistent_gnt);
1265                 }
1266         }
1267         BUG_ON(rinfo->persistent_gnts_c != 0);
1268
1269         for (i = 0; i < BLK_RING_SIZE(info); i++) {
1270                 /*
1271                  * Clear persistent grants present in requests already
1272                  * on the shared ring
1273                  */
1274                 if (!rinfo->shadow[i].request)
1275                         goto free_shadow;
1276
1277                 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1278                        rinfo->shadow[i].req.u.indirect.nr_segments :
1279                        rinfo->shadow[i].req.u.rw.nr_segments;
1280                 for (j = 0; j < segs; j++) {
1281                         persistent_gnt = rinfo->shadow[i].grants_used[j];
1282                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1283                         if (info->feature_persistent)
1284                                 __free_page(persistent_gnt->page);
1285                         kfree(persistent_gnt);
1286                 }
1287
1288                 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1289                         /*
1290                          * If this is not an indirect operation don't try to
1291                          * free indirect segments
1292                          */
1293                         goto free_shadow;
1294
1295                 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1296                         persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1297                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1298                         __free_page(persistent_gnt->page);
1299                         kfree(persistent_gnt);
1300                 }
1301
1302 free_shadow:
1303                 kfree(rinfo->shadow[i].grants_used);
1304                 rinfo->shadow[i].grants_used = NULL;
1305                 kfree(rinfo->shadow[i].indirect_grants);
1306                 rinfo->shadow[i].indirect_grants = NULL;
1307                 kfree(rinfo->shadow[i].sg);
1308                 rinfo->shadow[i].sg = NULL;
1309         }
1310
1311         /* No more gnttab callback work. */
1312         gnttab_cancel_free_callback(&rinfo->callback);
1313
1314         /* Flush gnttab callback work. Must be done with no locks held. */
1315         flush_work(&rinfo->work);
1316
1317         /* Free resources associated with old device channel. */
1318         for (i = 0; i < info->nr_ring_pages; i++) {
1319                 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1320                         gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1321                         rinfo->ring_ref[i] = GRANT_INVALID_REF;
1322                 }
1323         }
1324         free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE));
1325         rinfo->ring.sring = NULL;
1326
1327         if (rinfo->irq)
1328                 unbind_from_irqhandler(rinfo->irq, rinfo);
1329         rinfo->evtchn = rinfo->irq = 0;
1330 }
1331
1332 static void blkif_free(struct blkfront_info *info, int suspend)
1333 {
1334         unsigned int i;
1335
1336         /* Prevent new requests being issued until we fix things up. */
1337         info->connected = suspend ?
1338                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1339         /* No more blkif_request(). */
1340         if (info->rq)
1341                 blk_mq_stop_hw_queues(info->rq);
1342
1343         for (i = 0; i < info->nr_rings; i++)
1344                 blkif_free_ring(&info->rinfo[i]);
1345
1346         kfree(info->rinfo);
1347         info->rinfo = NULL;
1348         info->nr_rings = 0;
1349 }
1350
1351 struct copy_from_grant {
1352         const struct blk_shadow *s;
1353         unsigned int grant_idx;
1354         unsigned int bvec_offset;
1355         char *bvec_data;
1356 };
1357
1358 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1359                                   unsigned int len, void *data)
1360 {
1361         struct copy_from_grant *info = data;
1362         char *shared_data;
1363         /* Convenient aliases */
1364         const struct blk_shadow *s = info->s;
1365
1366         shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1367
1368         memcpy(info->bvec_data + info->bvec_offset,
1369                shared_data + offset, len);
1370
1371         info->bvec_offset += len;
1372         info->grant_idx++;
1373
1374         kunmap_atomic(shared_data);
1375 }
1376
1377 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1378 {
1379         switch (rsp)
1380         {
1381         case BLKIF_RSP_OKAY:
1382                 return REQ_DONE;
1383         case BLKIF_RSP_EOPNOTSUPP:
1384                 return REQ_EOPNOTSUPP;
1385         case BLKIF_RSP_ERROR:
1386                 /* Fallthrough. */
1387         default:
1388                 return REQ_ERROR;
1389         }
1390 }
1391
1392 /*
1393  * Get the final status of the block request based on two ring response
1394  */
1395 static int blkif_get_final_status(enum blk_req_status s1,
1396                                   enum blk_req_status s2)
1397 {
1398         BUG_ON(s1 == REQ_WAITING);
1399         BUG_ON(s2 == REQ_WAITING);
1400
1401         if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1402                 return BLKIF_RSP_ERROR;
1403         else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1404                 return BLKIF_RSP_EOPNOTSUPP;
1405         return BLKIF_RSP_OKAY;
1406 }
1407
1408 static bool blkif_completion(unsigned long *id,
1409                              struct blkfront_ring_info *rinfo,
1410                              struct blkif_response *bret)
1411 {
1412         int i = 0;
1413         struct scatterlist *sg;
1414         int num_sg, num_grant;
1415         struct blkfront_info *info = rinfo->dev_info;
1416         struct blk_shadow *s = &rinfo->shadow[*id];
1417         struct copy_from_grant data = {
1418                 .grant_idx = 0,
1419         };
1420
1421         num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1422                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1423
1424         /* The I/O request may be split in two. */
1425         if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1426                 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1427
1428                 /* Keep the status of the current response in shadow. */
1429                 s->status = blkif_rsp_to_req_status(bret->status);
1430
1431                 /* Wait the second response if not yet here. */
1432                 if (s2->status == REQ_WAITING)
1433                         return 0;
1434
1435                 bret->status = blkif_get_final_status(s->status,
1436                                                       s2->status);
1437
1438                 /*
1439                  * All the grants is stored in the first shadow in order
1440                  * to make the completion code simpler.
1441                  */
1442                 num_grant += s2->req.u.rw.nr_segments;
1443
1444                 /*
1445                  * The two responses may not come in order. Only the
1446                  * first request will store the scatter-gather list.
1447                  */
1448                 if (s2->num_sg != 0) {
1449                         /* Update "id" with the ID of the first response. */
1450                         *id = s->associated_id;
1451                         s = s2;
1452                 }
1453
1454                 /*
1455                  * We don't need anymore the second request, so recycling
1456                  * it now.
1457                  */
1458                 if (add_id_to_freelist(rinfo, s->associated_id))
1459                         WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1460                              info->gd->disk_name, s->associated_id);
1461         }
1462
1463         data.s = s;
1464         num_sg = s->num_sg;
1465
1466         if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1467                 for_each_sg(s->sg, sg, num_sg, i) {
1468                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1469
1470                         data.bvec_offset = sg->offset;
1471                         data.bvec_data = kmap_atomic(sg_page(sg));
1472
1473                         gnttab_foreach_grant_in_range(sg_page(sg),
1474                                                       sg->offset,
1475                                                       sg->length,
1476                                                       blkif_copy_from_grant,
1477                                                       &data);
1478
1479                         kunmap_atomic(data.bvec_data);
1480                 }
1481         }
1482         /* Add the persistent grant into the list of free grants */
1483         for (i = 0; i < num_grant; i++) {
1484                 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1485                         /*
1486                          * If the grant is still mapped by the backend (the
1487                          * backend has chosen to make this grant persistent)
1488                          * we add it at the head of the list, so it will be
1489                          * reused first.
1490                          */
1491                         if (!info->feature_persistent)
1492                                 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1493                                                      s->grants_used[i]->gref);
1494                         list_add(&s->grants_used[i]->node, &rinfo->grants);
1495                         rinfo->persistent_gnts_c++;
1496                 } else {
1497                         /*
1498                          * If the grant is not mapped by the backend we end the
1499                          * foreign access and add it to the tail of the list,
1500                          * so it will not be picked again unless we run out of
1501                          * persistent grants.
1502                          */
1503                         gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1504                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1505                         list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1506                 }
1507         }
1508         if (s->req.operation == BLKIF_OP_INDIRECT) {
1509                 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1510                         if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1511                                 if (!info->feature_persistent)
1512                                         pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1513                                                              s->indirect_grants[i]->gref);
1514                                 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1515                                 rinfo->persistent_gnts_c++;
1516                         } else {
1517                                 struct page *indirect_page;
1518
1519                                 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1520                                 /*
1521                                  * Add the used indirect page back to the list of
1522                                  * available pages for indirect grefs.
1523                                  */
1524                                 if (!info->feature_persistent) {
1525                                         indirect_page = s->indirect_grants[i]->page;
1526                                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
1527                                 }
1528                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1529                                 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1530                         }
1531                 }
1532         }
1533
1534         return 1;
1535 }
1536
1537 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1538 {
1539         struct request *req;
1540         struct blkif_response *bret;
1541         RING_IDX i, rp;
1542         unsigned long flags;
1543         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1544         struct blkfront_info *info = rinfo->dev_info;
1545         int error;
1546
1547         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1548                 return IRQ_HANDLED;
1549
1550         spin_lock_irqsave(&rinfo->ring_lock, flags);
1551  again:
1552         rp = rinfo->ring.sring->rsp_prod;
1553         rmb(); /* Ensure we see queued responses up to 'rp'. */
1554
1555         for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1556                 unsigned long id;
1557
1558                 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1559                 id   = bret->id;
1560                 /*
1561                  * The backend has messed up and given us an id that we would
1562                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1563                  * look in get_id_from_freelist.
1564                  */
1565                 if (id >= BLK_RING_SIZE(info)) {
1566                         WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1567                              info->gd->disk_name, op_name(bret->operation), id);
1568                         /* We can't safely get the 'struct request' as
1569                          * the id is busted. */
1570                         continue;
1571                 }
1572                 req  = rinfo->shadow[id].request;
1573
1574                 if (bret->operation != BLKIF_OP_DISCARD) {
1575                         /*
1576                          * We may need to wait for an extra response if the
1577                          * I/O request is split in 2
1578                          */
1579                         if (!blkif_completion(&id, rinfo, bret))
1580                                 continue;
1581                 }
1582
1583                 if (add_id_to_freelist(rinfo, id)) {
1584                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1585                              info->gd->disk_name, op_name(bret->operation), id);
1586                         continue;
1587                 }
1588
1589                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1590                 switch (bret->operation) {
1591                 case BLKIF_OP_DISCARD:
1592                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1593                                 struct request_queue *rq = info->rq;
1594                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1595                                            info->gd->disk_name, op_name(bret->operation));
1596                                 error = -EOPNOTSUPP;
1597                                 info->feature_discard = 0;
1598                                 info->feature_secdiscard = 0;
1599                                 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1600                                 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1601                         }
1602                         blk_mq_complete_request(req, error);
1603                         break;
1604                 case BLKIF_OP_FLUSH_DISKCACHE:
1605                 case BLKIF_OP_WRITE_BARRIER:
1606                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1607                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1608                                        info->gd->disk_name, op_name(bret->operation));
1609                                 error = -EOPNOTSUPP;
1610                         }
1611                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1612                                      rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1613                                 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1614                                        info->gd->disk_name, op_name(bret->operation));
1615                                 error = -EOPNOTSUPP;
1616                         }
1617                         if (unlikely(error)) {
1618                                 if (error == -EOPNOTSUPP)
1619                                         error = 0;
1620                                 info->feature_flush = 0;
1621                                 xlvbd_flush(info);
1622                         }
1623                         /* fall through */
1624                 case BLKIF_OP_READ:
1625                 case BLKIF_OP_WRITE:
1626                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
1627                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1628                                         "request: %x\n", bret->status);
1629
1630                         blk_mq_complete_request(req, error);
1631                         break;
1632                 default:
1633                         BUG();
1634                 }
1635         }
1636
1637         rinfo->ring.rsp_cons = i;
1638
1639         if (i != rinfo->ring.req_prod_pvt) {
1640                 int more_to_do;
1641                 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1642                 if (more_to_do)
1643                         goto again;
1644         } else
1645                 rinfo->ring.sring->rsp_event = i + 1;
1646
1647         kick_pending_request_queues_locked(rinfo);
1648
1649         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1650
1651         return IRQ_HANDLED;
1652 }
1653
1654
1655 static int setup_blkring(struct xenbus_device *dev,
1656                          struct blkfront_ring_info *rinfo)
1657 {
1658         struct blkif_sring *sring;
1659         int err, i;
1660         struct blkfront_info *info = rinfo->dev_info;
1661         unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1662         grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1663
1664         for (i = 0; i < info->nr_ring_pages; i++)
1665                 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1666
1667         sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1668                                                        get_order(ring_size));
1669         if (!sring) {
1670                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1671                 return -ENOMEM;
1672         }
1673         SHARED_RING_INIT(sring);
1674         FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1675
1676         err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1677         if (err < 0) {
1678                 free_pages((unsigned long)sring, get_order(ring_size));
1679                 rinfo->ring.sring = NULL;
1680                 goto fail;
1681         }
1682         for (i = 0; i < info->nr_ring_pages; i++)
1683                 rinfo->ring_ref[i] = gref[i];
1684
1685         err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1686         if (err)
1687                 goto fail;
1688
1689         err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1690                                         "blkif", rinfo);
1691         if (err <= 0) {
1692                 xenbus_dev_fatal(dev, err,
1693                                  "bind_evtchn_to_irqhandler failed");
1694                 goto fail;
1695         }
1696         rinfo->irq = err;
1697
1698         return 0;
1699 fail:
1700         blkif_free(info, 0);
1701         return err;
1702 }
1703
1704 /*
1705  * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1706  * ring buffer may have multi pages depending on ->nr_ring_pages.
1707  */
1708 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1709                                 struct blkfront_ring_info *rinfo, const char *dir)
1710 {
1711         int err;
1712         unsigned int i;
1713         const char *message = NULL;
1714         struct blkfront_info *info = rinfo->dev_info;
1715
1716         if (info->nr_ring_pages == 1) {
1717                 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1718                 if (err) {
1719                         message = "writing ring-ref";
1720                         goto abort_transaction;
1721                 }
1722         } else {
1723                 for (i = 0; i < info->nr_ring_pages; i++) {
1724                         char ring_ref_name[RINGREF_NAME_LEN];
1725
1726                         snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1727                         err = xenbus_printf(xbt, dir, ring_ref_name,
1728                                             "%u", rinfo->ring_ref[i]);
1729                         if (err) {
1730                                 message = "writing ring-ref";
1731                                 goto abort_transaction;
1732                         }
1733                 }
1734         }
1735
1736         err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1737         if (err) {
1738                 message = "writing event-channel";
1739                 goto abort_transaction;
1740         }
1741
1742         return 0;
1743
1744 abort_transaction:
1745         xenbus_transaction_end(xbt, 1);
1746         if (message)
1747                 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1748
1749         return err;
1750 }
1751
1752 /* Common code used when first setting up, and when resuming. */
1753 static int talk_to_blkback(struct xenbus_device *dev,
1754                            struct blkfront_info *info)
1755 {
1756         const char *message = NULL;
1757         struct xenbus_transaction xbt;
1758         int err;
1759         unsigned int i, max_page_order = 0;
1760         unsigned int ring_page_order = 0;
1761
1762         err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1763                            "max-ring-page-order", "%u", &max_page_order);
1764         if (err != 1)
1765                 info->nr_ring_pages = 1;
1766         else {
1767                 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1768                 info->nr_ring_pages = 1 << ring_page_order;
1769         }
1770
1771         for (i = 0; i < info->nr_rings; i++) {
1772                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1773
1774                 /* Create shared ring, alloc event channel. */
1775                 err = setup_blkring(dev, rinfo);
1776                 if (err)
1777                         goto destroy_blkring;
1778         }
1779
1780 again:
1781         err = xenbus_transaction_start(&xbt);
1782         if (err) {
1783                 xenbus_dev_fatal(dev, err, "starting transaction");
1784                 goto destroy_blkring;
1785         }
1786
1787         if (info->nr_ring_pages > 1) {
1788                 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1789                                     ring_page_order);
1790                 if (err) {
1791                         message = "writing ring-page-order";
1792                         goto abort_transaction;
1793                 }
1794         }
1795
1796         /* We already got the number of queues/rings in _probe */
1797         if (info->nr_rings == 1) {
1798                 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1799                 if (err)
1800                         goto destroy_blkring;
1801         } else {
1802                 char *path;
1803                 size_t pathsize;
1804
1805                 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1806                                     info->nr_rings);
1807                 if (err) {
1808                         message = "writing multi-queue-num-queues";
1809                         goto abort_transaction;
1810                 }
1811
1812                 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1813                 path = kmalloc(pathsize, GFP_KERNEL);
1814                 if (!path) {
1815                         err = -ENOMEM;
1816                         message = "ENOMEM while writing ring references";
1817                         goto abort_transaction;
1818                 }
1819
1820                 for (i = 0; i < info->nr_rings; i++) {
1821                         memset(path, 0, pathsize);
1822                         snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1823                         err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1824                         if (err) {
1825                                 kfree(path);
1826                                 goto destroy_blkring;
1827                         }
1828                 }
1829                 kfree(path);
1830         }
1831         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1832                             XEN_IO_PROTO_ABI_NATIVE);
1833         if (err) {
1834                 message = "writing protocol";
1835                 goto abort_transaction;
1836         }
1837         err = xenbus_printf(xbt, dev->nodename,
1838                             "feature-persistent", "%u", 1);
1839         if (err)
1840                 dev_warn(&dev->dev,
1841                          "writing persistent grants feature to xenbus");
1842
1843         err = xenbus_transaction_end(xbt, 0);
1844         if (err) {
1845                 if (err == -EAGAIN)
1846                         goto again;
1847                 xenbus_dev_fatal(dev, err, "completing transaction");
1848                 goto destroy_blkring;
1849         }
1850
1851         for (i = 0; i < info->nr_rings; i++) {
1852                 unsigned int j;
1853                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1854
1855                 for (j = 0; j < BLK_RING_SIZE(info); j++)
1856                         rinfo->shadow[j].req.u.rw.id = j + 1;
1857                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1858         }
1859         xenbus_switch_state(dev, XenbusStateInitialised);
1860
1861         return 0;
1862
1863  abort_transaction:
1864         xenbus_transaction_end(xbt, 1);
1865         if (message)
1866                 xenbus_dev_fatal(dev, err, "%s", message);
1867  destroy_blkring:
1868         blkif_free(info, 0);
1869
1870         kfree(info);
1871         dev_set_drvdata(&dev->dev, NULL);
1872
1873         return err;
1874 }
1875
1876 static int negotiate_mq(struct blkfront_info *info)
1877 {
1878         unsigned int backend_max_queues = 0;
1879         int err;
1880         unsigned int i;
1881
1882         BUG_ON(info->nr_rings);
1883
1884         /* Check if backend supports multiple queues. */
1885         err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1886                            "multi-queue-max-queues", "%u", &backend_max_queues);
1887         if (err < 0)
1888                 backend_max_queues = 1;
1889
1890         info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1891         /* We need at least one ring. */
1892         if (!info->nr_rings)
1893                 info->nr_rings = 1;
1894
1895         info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
1896         if (!info->rinfo) {
1897                 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1898                 return -ENOMEM;
1899         }
1900
1901         for (i = 0; i < info->nr_rings; i++) {
1902                 struct blkfront_ring_info *rinfo;
1903
1904                 rinfo = &info->rinfo[i];
1905                 INIT_LIST_HEAD(&rinfo->indirect_pages);
1906                 INIT_LIST_HEAD(&rinfo->grants);
1907                 rinfo->dev_info = info;
1908                 INIT_WORK(&rinfo->work, blkif_restart_queue);
1909                 spin_lock_init(&rinfo->ring_lock);
1910         }
1911         return 0;
1912 }
1913 /**
1914  * Entry point to this code when a new device is created.  Allocate the basic
1915  * structures and the ring buffer for communication with the backend, and
1916  * inform the backend of the appropriate details for those.  Switch to
1917  * Initialised state.
1918  */
1919 static int blkfront_probe(struct xenbus_device *dev,
1920                           const struct xenbus_device_id *id)
1921 {
1922         int err, vdevice;
1923         struct blkfront_info *info;
1924
1925         /* FIXME: Use dynamic device id if this is not set. */
1926         err = xenbus_scanf(XBT_NIL, dev->nodename,
1927                            "virtual-device", "%i", &vdevice);
1928         if (err != 1) {
1929                 /* go looking in the extended area instead */
1930                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1931                                    "%i", &vdevice);
1932                 if (err != 1) {
1933                         xenbus_dev_fatal(dev, err, "reading virtual-device");
1934                         return err;
1935                 }
1936         }
1937
1938         if (xen_hvm_domain()) {
1939                 char *type;
1940                 int len;
1941                 /* no unplug has been done: do not hook devices != xen vbds */
1942                 if (xen_has_pv_and_legacy_disk_devices()) {
1943                         int major;
1944
1945                         if (!VDEV_IS_EXTENDED(vdevice))
1946                                 major = BLKIF_MAJOR(vdevice);
1947                         else
1948                                 major = XENVBD_MAJOR;
1949
1950                         if (major != XENVBD_MAJOR) {
1951                                 printk(KERN_INFO
1952                                                 "%s: HVM does not support vbd %d as xen block device\n",
1953                                                 __func__, vdevice);
1954                                 return -ENODEV;
1955                         }
1956                 }
1957                 /* do not create a PV cdrom device if we are an HVM guest */
1958                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1959                 if (IS_ERR(type))
1960                         return -ENODEV;
1961                 if (strncmp(type, "cdrom", 5) == 0) {
1962                         kfree(type);
1963                         return -ENODEV;
1964                 }
1965                 kfree(type);
1966         }
1967         info = kzalloc(sizeof(*info), GFP_KERNEL);
1968         if (!info) {
1969                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1970                 return -ENOMEM;
1971         }
1972
1973         info->xbdev = dev;
1974         err = negotiate_mq(info);
1975         if (err) {
1976                 kfree(info);
1977                 return err;
1978         }
1979
1980         mutex_init(&info->mutex);
1981         info->vdevice = vdevice;
1982         info->connected = BLKIF_STATE_DISCONNECTED;
1983
1984         /* Front end dir is a number, which is used as the id. */
1985         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1986         dev_set_drvdata(&dev->dev, info);
1987
1988         return 0;
1989 }
1990
1991 static void split_bio_end(struct bio *bio)
1992 {
1993         struct split_bio *split_bio = bio->bi_private;
1994
1995         if (atomic_dec_and_test(&split_bio->pending)) {
1996                 split_bio->bio->bi_phys_segments = 0;
1997                 split_bio->bio->bi_error = bio->bi_error;
1998                 bio_endio(split_bio->bio);
1999                 kfree(split_bio);
2000         }
2001         bio_put(bio);
2002 }
2003
2004 static int blkif_recover(struct blkfront_info *info)
2005 {
2006         unsigned int i, r_index;
2007         struct request *req, *n;
2008         int rc;
2009         struct bio *bio, *cloned_bio;
2010         unsigned int segs, offset;
2011         int pending, size;
2012         struct split_bio *split_bio;
2013
2014         blkfront_gather_backend_features(info);
2015         segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2016         blk_queue_max_segments(info->rq, segs);
2017
2018         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2019                 struct blkfront_ring_info *rinfo = &info->rinfo[r_index];
2020
2021                 rc = blkfront_setup_indirect(rinfo);
2022                 if (rc)
2023                         return rc;
2024         }
2025         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2026
2027         /* Now safe for us to use the shared ring */
2028         info->connected = BLKIF_STATE_CONNECTED;
2029
2030         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2031                 struct blkfront_ring_info *rinfo;
2032
2033                 rinfo = &info->rinfo[r_index];
2034                 /* Kick any other new requests queued since we resumed */
2035                 kick_pending_request_queues(rinfo);
2036         }
2037
2038         list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2039                 /* Requeue pending requests (flush or discard) */
2040                 list_del_init(&req->queuelist);
2041                 BUG_ON(req->nr_phys_segments > segs);
2042                 blk_mq_requeue_request(req);
2043         }
2044         blk_mq_kick_requeue_list(info->rq);
2045
2046         while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2047                 /* Traverse the list of pending bios and re-queue them */
2048                 if (bio_segments(bio) > segs) {
2049                         /*
2050                          * This bio has more segments than what we can
2051                          * handle, we have to split it.
2052                          */
2053                         pending = (bio_segments(bio) + segs - 1) / segs;
2054                         split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
2055                         BUG_ON(split_bio == NULL);
2056                         atomic_set(&split_bio->pending, pending);
2057                         split_bio->bio = bio;
2058                         for (i = 0; i < pending; i++) {
2059                                 offset = (i * segs * XEN_PAGE_SIZE) >> 9;
2060                                 size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9,
2061                                            (unsigned int)bio_sectors(bio) - offset);
2062                                 cloned_bio = bio_clone(bio, GFP_NOIO);
2063                                 BUG_ON(cloned_bio == NULL);
2064                                 bio_trim(cloned_bio, offset, size);
2065                                 cloned_bio->bi_private = split_bio;
2066                                 cloned_bio->bi_end_io = split_bio_end;
2067                                 submit_bio(cloned_bio->bi_rw, cloned_bio);
2068                         }
2069                         /*
2070                          * Now we have to wait for all those smaller bios to
2071                          * end, so we can also end the "parent" bio.
2072                          */
2073                         continue;
2074                 }
2075                 /* We don't need to split this bio */
2076                 submit_bio(bio->bi_rw, bio);
2077         }
2078
2079         return 0;
2080 }
2081
2082 /**
2083  * We are reconnecting to the backend, due to a suspend/resume, or a backend
2084  * driver restart.  We tear down our blkif structure and recreate it, but
2085  * leave the device-layer structures intact so that this is transparent to the
2086  * rest of the kernel.
2087  */
2088 static int blkfront_resume(struct xenbus_device *dev)
2089 {
2090         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2091         int err = 0;
2092         unsigned int i, j;
2093
2094         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2095
2096         bio_list_init(&info->bio_list);
2097         INIT_LIST_HEAD(&info->requests);
2098         for (i = 0; i < info->nr_rings; i++) {
2099                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2100                 struct bio_list merge_bio;
2101                 struct blk_shadow *shadow = rinfo->shadow;
2102
2103                 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2104                         /* Not in use? */
2105                         if (!shadow[j].request)
2106                                 continue;
2107
2108                         /*
2109                          * Get the bios in the request so we can re-queue them.
2110                          */
2111                         if (shadow[j].request->cmd_flags &
2112                                         (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
2113                                 /*
2114                                  * Flush operations don't contain bios, so
2115                                  * we need to requeue the whole request
2116                                  */
2117                                 list_add(&shadow[j].request->queuelist, &info->requests);
2118                                 continue;
2119                         }
2120                         merge_bio.head = shadow[j].request->bio;
2121                         merge_bio.tail = shadow[j].request->biotail;
2122                         bio_list_merge(&info->bio_list, &merge_bio);
2123                         shadow[j].request->bio = NULL;
2124                         blk_mq_end_request(shadow[j].request, 0);
2125                 }
2126         }
2127
2128         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2129
2130         err = negotiate_mq(info);
2131         if (err)
2132                 return err;
2133
2134         err = talk_to_blkback(dev, info);
2135         if (!err)
2136                 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2137
2138         /*
2139          * We have to wait for the backend to switch to
2140          * connected state, since we want to read which
2141          * features it supports.
2142          */
2143
2144         return err;
2145 }
2146
2147 static void blkfront_closing(struct blkfront_info *info)
2148 {
2149         struct xenbus_device *xbdev = info->xbdev;
2150         struct block_device *bdev = NULL;
2151
2152         mutex_lock(&info->mutex);
2153
2154         if (xbdev->state == XenbusStateClosing) {
2155                 mutex_unlock(&info->mutex);
2156                 return;
2157         }
2158
2159         if (info->gd)
2160                 bdev = bdget_disk(info->gd, 0);
2161
2162         mutex_unlock(&info->mutex);
2163
2164         if (!bdev) {
2165                 xenbus_frontend_closed(xbdev);
2166                 return;
2167         }
2168
2169         mutex_lock(&bdev->bd_mutex);
2170
2171         if (bdev->bd_openers) {
2172                 xenbus_dev_error(xbdev, -EBUSY,
2173                                  "Device in use; refusing to close");
2174                 xenbus_switch_state(xbdev, XenbusStateClosing);
2175         } else {
2176                 xlvbd_release_gendisk(info);
2177                 xenbus_frontend_closed(xbdev);
2178         }
2179
2180         mutex_unlock(&bdev->bd_mutex);
2181         bdput(bdev);
2182 }
2183
2184 static void blkfront_setup_discard(struct blkfront_info *info)
2185 {
2186         int err;
2187         unsigned int discard_granularity;
2188         unsigned int discard_alignment;
2189         unsigned int discard_secure;
2190
2191         info->feature_discard = 1;
2192         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2193                 "discard-granularity", "%u", &discard_granularity,
2194                 "discard-alignment", "%u", &discard_alignment,
2195                 NULL);
2196         if (!err) {
2197                 info->discard_granularity = discard_granularity;
2198                 info->discard_alignment = discard_alignment;
2199         }
2200         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2201                     "discard-secure", "%d", &discard_secure,
2202                     NULL);
2203         if (!err)
2204                 info->feature_secdiscard = !!discard_secure;
2205 }
2206
2207 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2208 {
2209         unsigned int psegs, grants;
2210         int err, i;
2211         struct blkfront_info *info = rinfo->dev_info;
2212
2213         if (info->max_indirect_segments == 0) {
2214                 if (!HAS_EXTRA_REQ)
2215                         grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2216                 else {
2217                         /*
2218                          * When an extra req is required, the maximum
2219                          * grants supported is related to the size of the
2220                          * Linux block segment.
2221                          */
2222                         grants = GRANTS_PER_PSEG;
2223                 }
2224         }
2225         else
2226                 grants = info->max_indirect_segments;
2227         psegs = grants / GRANTS_PER_PSEG;
2228
2229         err = fill_grant_buffer(rinfo,
2230                                 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2231         if (err)
2232                 goto out_of_memory;
2233
2234         if (!info->feature_persistent && info->max_indirect_segments) {
2235                 /*
2236                  * We are using indirect descriptors but not persistent
2237                  * grants, we need to allocate a set of pages that can be
2238                  * used for mapping indirect grefs
2239                  */
2240                 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2241
2242                 BUG_ON(!list_empty(&rinfo->indirect_pages));
2243                 for (i = 0; i < num; i++) {
2244                         struct page *indirect_page = alloc_page(GFP_NOIO);
2245                         if (!indirect_page)
2246                                 goto out_of_memory;
2247                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
2248                 }
2249         }
2250
2251         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2252                 rinfo->shadow[i].grants_used = kzalloc(
2253                         sizeof(rinfo->shadow[i].grants_used[0]) * grants,
2254                         GFP_NOIO);
2255                 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO);
2256                 if (info->max_indirect_segments)
2257                         rinfo->shadow[i].indirect_grants = kzalloc(
2258                                 sizeof(rinfo->shadow[i].indirect_grants[0]) *
2259                                 INDIRECT_GREFS(grants),
2260                                 GFP_NOIO);
2261                 if ((rinfo->shadow[i].grants_used == NULL) ||
2262                         (rinfo->shadow[i].sg == NULL) ||
2263                      (info->max_indirect_segments &&
2264                      (rinfo->shadow[i].indirect_grants == NULL)))
2265                         goto out_of_memory;
2266                 sg_init_table(rinfo->shadow[i].sg, psegs);
2267         }
2268
2269
2270         return 0;
2271
2272 out_of_memory:
2273         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2274                 kfree(rinfo->shadow[i].grants_used);
2275                 rinfo->shadow[i].grants_used = NULL;
2276                 kfree(rinfo->shadow[i].sg);
2277                 rinfo->shadow[i].sg = NULL;
2278                 kfree(rinfo->shadow[i].indirect_grants);
2279                 rinfo->shadow[i].indirect_grants = NULL;
2280         }
2281         if (!list_empty(&rinfo->indirect_pages)) {
2282                 struct page *indirect_page, *n;
2283                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2284                         list_del(&indirect_page->lru);
2285                         __free_page(indirect_page);
2286                 }
2287         }
2288         return -ENOMEM;
2289 }
2290
2291 /*
2292  * Gather all backend feature-*
2293  */
2294 static void blkfront_gather_backend_features(struct blkfront_info *info)
2295 {
2296         int err;
2297         int barrier, flush, discard, persistent;
2298         unsigned int indirect_segments;
2299
2300         info->feature_flush = 0;
2301
2302         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2303                         "feature-barrier", "%d", &barrier,
2304                         NULL);
2305
2306         /*
2307          * If there's no "feature-barrier" defined, then it means
2308          * we're dealing with a very old backend which writes
2309          * synchronously; nothing to do.
2310          *
2311          * If there are barriers, then we use flush.
2312          */
2313         if (!err && barrier)
2314                 info->feature_flush = REQ_FLUSH | REQ_FUA;
2315         /*
2316          * And if there is "feature-flush-cache" use that above
2317          * barriers.
2318          */
2319         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2320                         "feature-flush-cache", "%d", &flush,
2321                         NULL);
2322
2323         if (!err && flush)
2324                 info->feature_flush = REQ_FLUSH;
2325
2326         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2327                         "feature-discard", "%d", &discard,
2328                         NULL);
2329
2330         if (!err && discard)
2331                 blkfront_setup_discard(info);
2332
2333         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2334                         "feature-persistent", "%u", &persistent,
2335                         NULL);
2336         if (err)
2337                 info->feature_persistent = 0;
2338         else
2339                 info->feature_persistent = persistent;
2340
2341         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2342                             "feature-max-indirect-segments", "%u", &indirect_segments,
2343                             NULL);
2344         if (err)
2345                 info->max_indirect_segments = 0;
2346         else
2347                 info->max_indirect_segments = min(indirect_segments,
2348                                                   xen_blkif_max_segments);
2349 }
2350
2351 /*
2352  * Invoked when the backend is finally 'ready' (and has told produced
2353  * the details about the physical device - #sectors, size, etc).
2354  */
2355 static void blkfront_connect(struct blkfront_info *info)
2356 {
2357         unsigned long long sectors;
2358         unsigned long sector_size;
2359         unsigned int physical_sector_size;
2360         unsigned int binfo;
2361         int err, i;
2362
2363         switch (info->connected) {
2364         case BLKIF_STATE_CONNECTED:
2365                 /*
2366                  * Potentially, the back-end may be signalling
2367                  * a capacity change; update the capacity.
2368                  */
2369                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2370                                    "sectors", "%Lu", &sectors);
2371                 if (XENBUS_EXIST_ERR(err))
2372                         return;
2373                 printk(KERN_INFO "Setting capacity to %Lu\n",
2374                        sectors);
2375                 set_capacity(info->gd, sectors);
2376                 revalidate_disk(info->gd);
2377
2378                 return;
2379         case BLKIF_STATE_SUSPENDED:
2380                 /*
2381                  * If we are recovering from suspension, we need to wait
2382                  * for the backend to announce it's features before
2383                  * reconnecting, at least we need to know if the backend
2384                  * supports indirect descriptors, and how many.
2385                  */
2386                 blkif_recover(info);
2387                 return;
2388
2389         default:
2390                 break;
2391         }
2392
2393         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2394                 __func__, info->xbdev->otherend);
2395
2396         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2397                             "sectors", "%llu", &sectors,
2398                             "info", "%u", &binfo,
2399                             "sector-size", "%lu", &sector_size,
2400                             NULL);
2401         if (err) {
2402                 xenbus_dev_fatal(info->xbdev, err,
2403                                  "reading backend fields at %s",
2404                                  info->xbdev->otherend);
2405                 return;
2406         }
2407
2408         /*
2409          * physcial-sector-size is a newer field, so old backends may not
2410          * provide this. Assume physical sector size to be the same as
2411          * sector_size in that case.
2412          */
2413         err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2414                            "physical-sector-size", "%u", &physical_sector_size);
2415         if (err != 1)
2416                 physical_sector_size = sector_size;
2417
2418         blkfront_gather_backend_features(info);
2419         for (i = 0; i < info->nr_rings; i++) {
2420                 err = blkfront_setup_indirect(&info->rinfo[i]);
2421                 if (err) {
2422                         xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2423                                          info->xbdev->otherend);
2424                         blkif_free(info, 0);
2425                         break;
2426                 }
2427         }
2428
2429         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2430                                   physical_sector_size);
2431         if (err) {
2432                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2433                                  info->xbdev->otherend);
2434                 return;
2435         }
2436
2437         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2438
2439         /* Kick pending requests. */
2440         info->connected = BLKIF_STATE_CONNECTED;
2441         for (i = 0; i < info->nr_rings; i++)
2442                 kick_pending_request_queues(&info->rinfo[i]);
2443
2444         add_disk(info->gd);
2445
2446         info->is_ready = 1;
2447 }
2448
2449 /**
2450  * Callback received when the backend's state changes.
2451  */
2452 static void blkback_changed(struct xenbus_device *dev,
2453                             enum xenbus_state backend_state)
2454 {
2455         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2456
2457         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2458
2459         switch (backend_state) {
2460         case XenbusStateInitWait:
2461                 if (dev->state != XenbusStateInitialising)
2462                         break;
2463                 if (talk_to_blkback(dev, info))
2464                         break;
2465         case XenbusStateInitialising:
2466         case XenbusStateInitialised:
2467         case XenbusStateReconfiguring:
2468         case XenbusStateReconfigured:
2469         case XenbusStateUnknown:
2470                 break;
2471
2472         case XenbusStateConnected:
2473                 /*
2474                  * talk_to_blkback sets state to XenbusStateInitialised
2475                  * and blkfront_connect sets it to XenbusStateConnected
2476                  * (if connection went OK).
2477                  *
2478                  * If the backend (or toolstack) decides to poke at backend
2479                  * state (and re-trigger the watch by setting the state repeatedly
2480                  * to XenbusStateConnected (4)) we need to deal with this.
2481                  * This is allowed as this is used to communicate to the guest
2482                  * that the size of disk has changed!
2483                  */
2484                 if ((dev->state != XenbusStateInitialised) &&
2485                     (dev->state != XenbusStateConnected)) {
2486                         if (talk_to_blkback(dev, info))
2487                                 break;
2488                 }
2489
2490                 blkfront_connect(info);
2491                 break;
2492
2493         case XenbusStateClosed:
2494                 if (dev->state == XenbusStateClosed)
2495                         break;
2496                 /* Missed the backend's Closing state -- fallthrough */
2497         case XenbusStateClosing:
2498                 if (info)
2499                         blkfront_closing(info);
2500                 break;
2501         }
2502 }
2503
2504 static int blkfront_remove(struct xenbus_device *xbdev)
2505 {
2506         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2507         struct block_device *bdev = NULL;
2508         struct gendisk *disk;
2509
2510         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2511
2512         blkif_free(info, 0);
2513
2514         mutex_lock(&info->mutex);
2515
2516         disk = info->gd;
2517         if (disk)
2518                 bdev = bdget_disk(disk, 0);
2519
2520         info->xbdev = NULL;
2521         mutex_unlock(&info->mutex);
2522
2523         if (!bdev) {
2524                 kfree(info);
2525                 return 0;
2526         }
2527
2528         /*
2529          * The xbdev was removed before we reached the Closed
2530          * state. See if it's safe to remove the disk. If the bdev
2531          * isn't closed yet, we let release take care of it.
2532          */
2533
2534         mutex_lock(&bdev->bd_mutex);
2535         info = disk->private_data;
2536
2537         dev_warn(disk_to_dev(disk),
2538                  "%s was hot-unplugged, %d stale handles\n",
2539                  xbdev->nodename, bdev->bd_openers);
2540
2541         if (info && !bdev->bd_openers) {
2542                 xlvbd_release_gendisk(info);
2543                 disk->private_data = NULL;
2544                 kfree(info);
2545         }
2546
2547         mutex_unlock(&bdev->bd_mutex);
2548         bdput(bdev);
2549
2550         return 0;
2551 }
2552
2553 static int blkfront_is_ready(struct xenbus_device *dev)
2554 {
2555         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2556
2557         return info->is_ready && info->xbdev;
2558 }
2559
2560 static int blkif_open(struct block_device *bdev, fmode_t mode)
2561 {
2562         struct gendisk *disk = bdev->bd_disk;
2563         struct blkfront_info *info;
2564         int err = 0;
2565
2566         mutex_lock(&blkfront_mutex);
2567
2568         info = disk->private_data;
2569         if (!info) {
2570                 /* xbdev gone */
2571                 err = -ERESTARTSYS;
2572                 goto out;
2573         }
2574
2575         mutex_lock(&info->mutex);
2576
2577         if (!info->gd)
2578                 /* xbdev is closed */
2579                 err = -ERESTARTSYS;
2580
2581         mutex_unlock(&info->mutex);
2582
2583 out:
2584         mutex_unlock(&blkfront_mutex);
2585         return err;
2586 }
2587
2588 static void blkif_release(struct gendisk *disk, fmode_t mode)
2589 {
2590         struct blkfront_info *info = disk->private_data;
2591         struct block_device *bdev;
2592         struct xenbus_device *xbdev;
2593
2594         mutex_lock(&blkfront_mutex);
2595
2596         bdev = bdget_disk(disk, 0);
2597
2598         if (!bdev) {
2599                 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2600                 goto out_mutex;
2601         }
2602         if (bdev->bd_openers)
2603                 goto out;
2604
2605         /*
2606          * Check if we have been instructed to close. We will have
2607          * deferred this request, because the bdev was still open.
2608          */
2609
2610         mutex_lock(&info->mutex);
2611         xbdev = info->xbdev;
2612
2613         if (xbdev && xbdev->state == XenbusStateClosing) {
2614                 /* pending switch to state closed */
2615                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2616                 xlvbd_release_gendisk(info);
2617                 xenbus_frontend_closed(info->xbdev);
2618         }
2619
2620         mutex_unlock(&info->mutex);
2621
2622         if (!xbdev) {
2623                 /* sudden device removal */
2624                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2625                 xlvbd_release_gendisk(info);
2626                 disk->private_data = NULL;
2627                 kfree(info);
2628         }
2629
2630 out:
2631         bdput(bdev);
2632 out_mutex:
2633         mutex_unlock(&blkfront_mutex);
2634 }
2635
2636 static const struct block_device_operations xlvbd_block_fops =
2637 {
2638         .owner = THIS_MODULE,
2639         .open = blkif_open,
2640         .release = blkif_release,
2641         .getgeo = blkif_getgeo,
2642         .ioctl = blkif_ioctl,
2643 };
2644
2645
2646 static const struct xenbus_device_id blkfront_ids[] = {
2647         { "vbd" },
2648         { "" }
2649 };
2650
2651 static struct xenbus_driver blkfront_driver = {
2652         .ids  = blkfront_ids,
2653         .probe = blkfront_probe,
2654         .remove = blkfront_remove,
2655         .resume = blkfront_resume,
2656         .otherend_changed = blkback_changed,
2657         .is_ready = blkfront_is_ready,
2658 };
2659
2660 static int __init xlblk_init(void)
2661 {
2662         int ret;
2663         int nr_cpus = num_online_cpus();
2664
2665         if (!xen_domain())
2666                 return -ENODEV;
2667
2668         if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2669                 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2670                         xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2671                 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2672         }
2673
2674         if (xen_blkif_max_queues > nr_cpus) {
2675                 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2676                         xen_blkif_max_queues, nr_cpus);
2677                 xen_blkif_max_queues = nr_cpus;
2678         }
2679
2680         if (!xen_has_pv_disk_devices())
2681                 return -ENODEV;
2682
2683         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2684                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2685                        XENVBD_MAJOR, DEV_NAME);
2686                 return -ENODEV;
2687         }
2688
2689         ret = xenbus_register_frontend(&blkfront_driver);
2690         if (ret) {
2691                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2692                 return ret;
2693         }
2694
2695         return 0;
2696 }
2697 module_init(xlblk_init);
2698
2699
2700 static void __exit xlblk_exit(void)
2701 {
2702         xenbus_unregister_driver(&blkfront_driver);
2703         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2704         kfree(minors);
2705 }
2706 module_exit(xlblk_exit);
2707
2708 MODULE_DESCRIPTION("Xen virtual block device frontend");
2709 MODULE_LICENSE("GPL");
2710 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2711 MODULE_ALIAS("xen:vbd");
2712 MODULE_ALIAS("xenblk");