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 };
 211
 212 static unsigned int nr_minors;
 213 static unsigned long *minors;
 214 static DEFINE_SPINLOCK(minor_lock);
 215
 216 #define GRANT_INVALID_REF       0
 217
 218 #define PARTS_PER_DISK          16
 219 #define PARTS_PER_EXT_DISK      256
 220
 221 #define BLKIF_MAJOR(dev) ((dev)>>8)
 222 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 223
 224 #define EXT_SHIFT 28
 225 #define EXTENDED (1<<EXT_SHIFT)
 226 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 227 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 228 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 229 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 230 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 231 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 232
 233 #define DEV_NAME        "xvd"   /* name in /dev */
 234
 235 /*
 236  * Grants are always the same size as a Xen page (i.e 4KB).
 237  * A physical segment is always the same size as a Linux page.
 238  * Number of grants per physical segment
 239  */
 240 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
 241
 242 #define GRANTS_PER_INDIRECT_FRAME \
 243         (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
 244
 245 #define PSEGS_PER_INDIRECT_FRAME        \
 246         (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS)
 247
 248 #define INDIRECT_GREFS(_grants)         \
 249         DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
 250
 251 #define GREFS(_psegs)   ((_psegs) * GRANTS_PER_PSEG)
 252
 253 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 254 static void blkfront_gather_backend_features(struct blkfront_info *info);
 255
 256 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 257 {
 258         unsigned long free = rinfo->shadow_free;
 259
 260         BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
 261         rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
 262         rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 263         return free;
 264 }
 265
 266 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
 267                               unsigned long id)
 268 {
 269         if (rinfo->shadow[id].req.u.rw.id != id)
 270                 return -EINVAL;
 271         if (rinfo->shadow[id].request == NULL)
 272                 return -EINVAL;
 273         rinfo->shadow[id].req.u.rw.id  = rinfo->shadow_free;
 274         rinfo->shadow[id].request = NULL;
 275         rinfo->shadow_free = id;
 276         return 0;
 277 }
 278
 279 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 280 {
 281         struct blkfront_info *info = rinfo->dev_info;
 282         struct page *granted_page;
 283         struct grant *gnt_list_entry, *n;
 284         int i = 0;
 285
 286         while (i < num) {
 287                 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
 288                 if (!gnt_list_entry)
 289                         goto out_of_memory;
 290
 291                 if (info->feature_persistent) {
 292                         granted_page = alloc_page(GFP_NOIO);
 293                         if (!granted_page) {
 294                                 kfree(gnt_list_entry);
 295                                 goto out_of_memory;
 296                         }
 297                         gnt_list_entry->page = granted_page;
 298                 }
 299
 300                 gnt_list_entry->gref = GRANT_INVALID_REF;
 301                 list_add(&gnt_list_entry->node, &rinfo->grants);
 302                 i++;
 303         }
 304
 305         return 0;
 306
 307 out_of_memory:
 308         list_for_each_entry_safe(gnt_list_entry, n,
 309                                  &rinfo->grants, node) {
 310                 list_del(&gnt_list_entry->node);
 311                 if (info->feature_persistent)
 312                         __free_page(gnt_list_entry->page);
 313                 kfree(gnt_list_entry);
 314                 i--;
 315         }
 316         BUG_ON(i != 0);
 317         return -ENOMEM;
 318 }
 319
 320 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
 321 {
 322         struct grant *gnt_list_entry;
 323
 324         BUG_ON(list_empty(&rinfo->grants));
 325         gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
 326                                           node);
 327         list_del(&gnt_list_entry->node);
 328
 329         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 330                 rinfo->persistent_gnts_c--;
 331
 332         return gnt_list_entry;
 333 }
 334
 335 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
 336                                         const struct blkfront_info *info)
 337 {
 338         gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
 339                                                  info->xbdev->otherend_id,
 340                                                  gnt_list_entry->page,
 341                                                  0);
 342 }
 343
 344 static struct grant *get_grant(grant_ref_t *gref_head,
 345                                unsigned long gfn,
 346                                struct blkfront_ring_info *rinfo)
 347 {
 348         struct grant *gnt_list_entry = get_free_grant(rinfo);
 349         struct blkfront_info *info = rinfo->dev_info;
 350
 351         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 352                 return gnt_list_entry;
 353
 354         /* Assign a gref to this page */
 355         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 356         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 357         if (info->feature_persistent)
 358                 grant_foreign_access(gnt_list_entry, info);
 359         else {
 360                 /* Grant access to the GFN passed by the caller */
 361                 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
 362                                                 info->xbdev->otherend_id,
 363                                                 gfn, 0);
 364         }
 365
 366         return gnt_list_entry;
 367 }
 368
 369 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
 370                                         struct blkfront_ring_info *rinfo)
 371 {
 372         struct grant *gnt_list_entry = get_free_grant(rinfo);
 373         struct blkfront_info *info = rinfo->dev_info;
 374
 375         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 376                 return gnt_list_entry;
 377
 378         /* Assign a gref to this page */
 379         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 380         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 381         if (!info->feature_persistent) {
 382                 struct page *indirect_page;
 383
 384                 /* Fetch a pre-allocated page to use for indirect grefs */
 385                 BUG_ON(list_empty(&rinfo->indirect_pages));
 386                 indirect_page = list_first_entry(&rinfo->indirect_pages,
 387                                                  struct page, lru);
 388                 list_del(&indirect_page->lru);
 389                 gnt_list_entry->page = indirect_page;
 390         }
 391         grant_foreign_access(gnt_list_entry, info);
 392
 393         return gnt_list_entry;
 394 }
 395
 396 static const char *op_name(int op)
 397 {
 398         static const char *const names[] = {
 399                 [BLKIF_OP_READ] = "read",
 400                 [BLKIF_OP_WRITE] = "write",
 401                 [BLKIF_OP_WRITE_BARRIER] = "barrier",
 402                 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
 403                 [BLKIF_OP_DISCARD] = "discard" };
 404
 405         if (op < 0 || op >= ARRAY_SIZE(names))
 406                 return "unknown";
 407
 408         if (!names[op])
 409                 return "reserved";
 410
 411         return names[op];
 412 }
 413 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 414 {
 415         unsigned int end = minor + nr;
 416         int rc;
 417
 418         if (end > nr_minors) {
 419                 unsigned long *bitmap, *old;
 420
 421                 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 422                                  GFP_KERNEL);
 423                 if (bitmap == NULL)
 424                         return -ENOMEM;
 425
 426                 spin_lock(&minor_lock);
 427                 if (end > nr_minors) {
 428                         old = minors;
 429                         memcpy(bitmap, minors,
 430                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 431                         minors = bitmap;
 432                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 433                 } else
 434                         old = bitmap;
 435                 spin_unlock(&minor_lock);
 436                 kfree(old);
 437         }
 438
 439         spin_lock(&minor_lock);
 440         if (find_next_bit(minors, end, minor) >= end) {
 441                 bitmap_set(minors, minor, nr);
 442                 rc = 0;
 443         } else
 444                 rc = -EBUSY;
 445         spin_unlock(&minor_lock);
 446
 447         return rc;
 448 }
 449
 450 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 451 {
 452         unsigned int end = minor + nr;
 453
 454         BUG_ON(end > nr_minors);
 455         spin_lock(&minor_lock);
 456         bitmap_clear(minors,  minor, nr);
 457         spin_unlock(&minor_lock);
 458 }
 459
 460 static void blkif_restart_queue_callback(void *arg)
 461 {
 462         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
 463         schedule_work(&rinfo->work);
 464 }
 465
 466 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 467 {
 468         /* We don't have real geometry info, but let's at least return
 469            values consistent with the size of the device */
 470         sector_t nsect = get_capacity(bd->bd_disk);
 471         sector_t cylinders = nsect;
 472
 473         hg->heads = 0xff;
 474         hg->sectors = 0x3f;
 475         sector_div(cylinders, hg->heads * hg->sectors);
 476         hg->cylinders = cylinders;
 477         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 478                 hg->cylinders = 0xffff;
 479         return 0;
 480 }
 481
 482 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 483                        unsigned command, unsigned long argument)
 484 {
 485         struct blkfront_info *info = bdev->bd_disk->private_data;
 486         int i;
 487
 488         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 489                 command, (long)argument);
 490
 491         switch (command) {
 492         case CDROMMULTISESSION:
 493                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 494                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 495                         if (put_user(0, (char __user *)(argument + i)))
 496                                 return -EFAULT;
 497                 return 0;
 498
 499         case CDROM_GET_CAPABILITY: {
 500                 struct gendisk *gd = info->gd;
 501                 if (gd->flags & GENHD_FL_CD)
 502                         return 0;
 503                 return -EINVAL;
 504         }
 505
 506         default:
 507                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 508                   command);*/
 509                 return -EINVAL; /* same return as native Linux */
 510         }
 511
 512         return 0;
 513 }
 514
 515 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 516                                             struct request *req,
 517                                             struct blkif_request **ring_req)
 518 {
 519         unsigned long id;
 520
 521         *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
 522         rinfo->ring.req_prod_pvt++;
 523
 524         id = get_id_from_freelist(rinfo);
 525         rinfo->shadow[id].request = req;
 526         rinfo->shadow[id].status = REQ_WAITING;
 527         rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
 528
 529         (*ring_req)->u.rw.id = id;
 530
 531         return id;
 532 }
 533
 534 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
 535 {
 536         struct blkfront_info *info = rinfo->dev_info;
 537         struct blkif_request *ring_req;
 538         unsigned long id;
 539
 540         /* Fill out a communications ring structure. */
 541         id = blkif_ring_get_request(rinfo, req, &ring_req);
 542
 543         ring_req->operation = BLKIF_OP_DISCARD;
 544         ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
 545         ring_req->u.discard.id = id;
 546         ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
 547         if ((req->cmd_flags & REQ_SECURE) && info->feature_secdiscard)
 548                 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
 549         else
 550                 ring_req->u.discard.flag = 0;
 551
 552         /* Keep a private copy so we can reissue requests when recovering. */
 553         rinfo->shadow[id].req = *ring_req;
 554
 555         return 0;
 556 }
 557
 558 struct setup_rw_req {
 559         unsigned int grant_idx;
 560         struct blkif_request_segment *segments;
 561         struct blkfront_ring_info *rinfo;
 562         struct blkif_request *ring_req;
 563         grant_ref_t gref_head;
 564         unsigned int id;
 565         /* Only used when persistent grant is used and it's a read request */
 566         bool need_copy;
 567         unsigned int bvec_off;
 568         char *bvec_data;
 569
 570         bool require_extra_req;
 571         struct blkif_request *extra_ring_req;
 572 };
 573
 574 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
 575                                      unsigned int len, void *data)
 576 {
 577         struct setup_rw_req *setup = data;
 578         int n, ref;
 579         struct grant *gnt_list_entry;
 580         unsigned int fsect, lsect;
 581         /* Convenient aliases */
 582         unsigned int grant_idx = setup->grant_idx;
 583         struct blkif_request *ring_req = setup->ring_req;
 584         struct blkfront_ring_info *rinfo = setup->rinfo;
 585         /*
 586          * We always use the shadow of the first request to store the list
 587          * of grant associated to the block I/O request. This made the
 588          * completion more easy to handle even if the block I/O request is
 589          * split.
 590          */
 591         struct blk_shadow *shadow = &rinfo->shadow[setup->id];
 592
 593         if (unlikely(setup->require_extra_req &&
 594                      grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
 595                 /*
 596                  * We are using the second request, setup grant_idx
 597                  * to be the index of the segment array.
 598                  */
 599                 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
 600                 ring_req = setup->extra_ring_req;
 601         }
 602
 603         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 604             (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
 605                 if (setup->segments)
 606                         kunmap_atomic(setup->segments);
 607
 608                 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
 609                 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
 610                 shadow->indirect_grants[n] = gnt_list_entry;
 611                 setup->segments = kmap_atomic(gnt_list_entry->page);
 612                 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 613         }
 614
 615         gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
 616         ref = gnt_list_entry->gref;
 617         /*
 618          * All the grants are stored in the shadow of the first
 619          * request. Therefore we have to use the global index.
 620          */
 621         shadow->grants_used[setup->grant_idx] = gnt_list_entry;
 622
 623         if (setup->need_copy) {
 624                 void *shared_data;
 625
 626                 shared_data = kmap_atomic(gnt_list_entry->page);
 627                 /*
 628                  * this does not wipe data stored outside the
 629                  * range sg->offset..sg->offset+sg->length.
 630                  * Therefore, blkback *could* see data from
 631                  * previous requests. This is OK as long as
 632                  * persistent grants are shared with just one
 633                  * domain. It may need refactoring if this
 634                  * changes
 635                  */
 636                 memcpy(shared_data + offset,
 637                        setup->bvec_data + setup->bvec_off,
 638                        len);
 639
 640                 kunmap_atomic(shared_data);
 641                 setup->bvec_off += len;
 642         }
 643
 644         fsect = offset >> 9;
 645         lsect = fsect + (len >> 9) - 1;
 646         if (ring_req->operation != BLKIF_OP_INDIRECT) {
 647                 ring_req->u.rw.seg[grant_idx] =
 648                         (struct blkif_request_segment) {
 649                                 .gref       = ref,
 650                                 .first_sect = fsect,
 651                                 .last_sect  = lsect };
 652         } else {
 653                 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
 654                         (struct blkif_request_segment) {
 655                                 .gref       = ref,
 656                                 .first_sect = fsect,
 657                                 .last_sect  = lsect };
 658         }
 659
 660         (setup->grant_idx)++;
 661 }
 662
 663 static void blkif_setup_extra_req(struct blkif_request *first,
 664                                   struct blkif_request *second)
 665 {
 666         uint16_t nr_segments = first->u.rw.nr_segments;
 667
 668         /*
 669          * The second request is only present when the first request uses
 670          * all its segments. It's always the continuity of the first one.
 671          */
 672         first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 673
 674         second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
 675         second->u.rw.sector_number = first->u.rw.sector_number +
 676                 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
 677
 678         second->u.rw.handle = first->u.rw.handle;
 679         second->operation = first->operation;
 680 }
 681
 682 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
 683 {
 684         struct blkfront_info *info = rinfo->dev_info;
 685         struct blkif_request *ring_req, *extra_ring_req = NULL;
 686         unsigned long id, extra_id = NO_ASSOCIATED_ID;
 687         bool require_extra_req = false;
 688         int i;
 689         struct setup_rw_req setup = {
 690                 .grant_idx = 0,
 691                 .segments = NULL,
 692                 .rinfo = rinfo,
 693                 .need_copy = rq_data_dir(req) && info->feature_persistent,
 694         };
 695
 696         /*
 697          * Used to store if we are able to queue the request by just using
 698          * existing persistent grants, or if we have to get new grants,
 699          * as there are not sufficiently many free.
 700          */
 701         struct scatterlist *sg;
 702         int num_sg, max_grefs, num_grant;
 703
 704         max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
 705         if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
 706                 /*
 707                  * If we are using indirect segments we need to account
 708                  * for the indirect grefs used in the request.
 709                  */
 710                 max_grefs += INDIRECT_GREFS(max_grefs);
 711
 712         /*
 713          * We have to reserve 'max_grefs' grants because persistent
 714          * grants are shared by all rings.
 715          */
 716         if (max_grefs > 0)
 717                 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) {
 718                         gnttab_request_free_callback(
 719                                 &rinfo->callback,
 720                                 blkif_restart_queue_callback,
 721                                 rinfo,
 722                                 max_grefs);
 723                         return 1;
 724                 }
 725
 726         /* Fill out a communications ring structure. */
 727         id = blkif_ring_get_request(rinfo, req, &ring_req);
 728
 729         num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 730         num_grant = 0;
 731         /* Calculate the number of grant used */
 732         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
 733                num_grant += gnttab_count_grant(sg->offset, sg->length);
 734
 735         require_extra_req = info->max_indirect_segments == 0 &&
 736                 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
 737         BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
 738
 739         rinfo->shadow[id].num_sg = num_sg;
 740         if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
 741             likely(!require_extra_req)) {
 742                 /*
 743                  * The indirect operation can only be a BLKIF_OP_READ or
 744                  * BLKIF_OP_WRITE
 745                  */
 746                 BUG_ON(req->cmd_flags & (REQ_FLUSH | REQ_FUA));
 747                 ring_req->operation = BLKIF_OP_INDIRECT;
 748                 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
 749                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 750                 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
 751                 ring_req->u.indirect.handle = info->handle;
 752                 ring_req->u.indirect.nr_segments = num_grant;
 753         } else {
 754                 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 755                 ring_req->u.rw.handle = info->handle;
 756                 ring_req->operation = rq_data_dir(req) ?
 757                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 758                 if (req->cmd_flags & (REQ_FLUSH | REQ_FUA)) {
 759                         /*
 760                          * Ideally we can do an unordered flush-to-disk.
 761                          * In case the backend onlysupports barriers, use that.
 762                          * A barrier request a superset of FUA, so we can
 763                          * implement it the same way.  (It's also a FLUSH+FUA,
 764                          * since it is guaranteed ordered WRT previous writes.)
 765                          */
 766                         switch (info->feature_flush &
 767                                 ((REQ_FLUSH|REQ_FUA))) {
 768                         case REQ_FLUSH|REQ_FUA:
 769                                 ring_req->operation =
 770                                         BLKIF_OP_WRITE_BARRIER;
 771                                 break;
 772                         case REQ_FLUSH:
 773                                 ring_req->operation =
 774                                         BLKIF_OP_FLUSH_DISKCACHE;
 775                                 break;
 776                         default:
 777                                 ring_req->operation = 0;
 778                         }
 779                 }
 780                 ring_req->u.rw.nr_segments = num_grant;
 781                 if (unlikely(require_extra_req)) {
 782                         extra_id = blkif_ring_get_request(rinfo, req,
 783                                                           &extra_ring_req);
 784                         /*
 785                          * Only the first request contains the scatter-gather
 786                          * list.
 787                          */
 788                         rinfo->shadow[extra_id].num_sg = 0;
 789
 790                         blkif_setup_extra_req(ring_req, extra_ring_req);
 791
 792                         /* Link the 2 requests together */
 793                         rinfo->shadow[extra_id].associated_id = id;
 794                         rinfo->shadow[id].associated_id = extra_id;
 795                 }
 796         }
 797
 798         setup.ring_req = ring_req;
 799         setup.id = id;
 800
 801         setup.require_extra_req = require_extra_req;
 802         if (unlikely(require_extra_req))
 803                 setup.extra_ring_req = extra_ring_req;
 804
 805         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
 806                 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
 807
 808                 if (setup.need_copy) {
 809                         setup.bvec_off = sg->offset;
 810                         setup.bvec_data = kmap_atomic(sg_page(sg));
 811                 }
 812
 813                 gnttab_foreach_grant_in_range(sg_page(sg),
 814                                               sg->offset,
 815                                               sg->length,
 816                                               blkif_setup_rw_req_grant,
 817                                               &setup);
 818
 819                 if (setup.need_copy)
 820                         kunmap_atomic(setup.bvec_data);
 821         }
 822         if (setup.segments)
 823                 kunmap_atomic(setup.segments);
 824
 825         /* Keep a private copy so we can reissue requests when recovering. */
 826         rinfo->shadow[id].req = *ring_req;
 827         if (unlikely(require_extra_req))
 828                 rinfo->shadow[extra_id].req = *extra_ring_req;
 829
 830         if (max_grefs > 0)
 831                 gnttab_free_grant_references(setup.gref_head);
 832
 833         return 0;
 834 }
 835
 836 /*
 837  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 838  * and writes are handled as expected.
 839  *
 840  * @req: a request struct
 841  */
 842 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
 843 {
 844         if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
 845                 return 1;
 846
 847         if (unlikely(req->cmd_flags & (REQ_DISCARD | REQ_SECURE)))
 848                 return blkif_queue_discard_req(req, rinfo);
 849         else
 850                 return blkif_queue_rw_req(req, rinfo);
 851 }
 852
 853 static inline void flush_requests(struct blkfront_ring_info *rinfo)
 854 {
 855         int notify;
 856
 857         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
 858
 859         if (notify)
 860                 notify_remote_via_irq(rinfo->irq);
 861 }
 862
 863 static inline bool blkif_request_flush_invalid(struct request *req,
 864                                                struct blkfront_info *info)
 865 {
 866         return ((req->cmd_type != REQ_TYPE_FS) ||
 867                 ((req->cmd_flags & REQ_FLUSH) &&
 868                  !(info->feature_flush & REQ_FLUSH)) ||
 869                 ((req->cmd_flags & REQ_FUA) &&
 870                  !(info->feature_flush & REQ_FUA)));
 871 }
 872
 873 static int blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
 874                           const struct blk_mq_queue_data *qd)
 875 {
 876         unsigned long flags;
 877         int qid = hctx->queue_num;
 878         struct blkfront_info *info = hctx->queue->queuedata;
 879         struct blkfront_ring_info *rinfo = NULL;
 880
 881         BUG_ON(info->nr_rings <= qid);
 882         rinfo = &info->rinfo[qid];
 883         blk_mq_start_request(qd->rq);
 884         spin_lock_irqsave(&rinfo->ring_lock, flags);
 885         if (RING_FULL(&rinfo->ring))
 886                 goto out_busy;
 887
 888         if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
 889                 goto out_err;
 890
 891         if (blkif_queue_request(qd->rq, rinfo))
 892                 goto out_busy;
 893
 894         flush_requests(rinfo);
 895         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 896         return BLK_MQ_RQ_QUEUE_OK;
 897
 898 out_err:
 899         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 900         return BLK_MQ_RQ_QUEUE_ERROR;
 901
 902 out_busy:
 903         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 904         blk_mq_stop_hw_queue(hctx);
 905         return BLK_MQ_RQ_QUEUE_BUSY;
 906 }
 907
 908 static struct blk_mq_ops blkfront_mq_ops = {
 909         .queue_rq = blkif_queue_rq,
 910         .map_queue = blk_mq_map_queue,
 911 };
 912
 913 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 914                                 unsigned int physical_sector_size,
 915                                 unsigned int segments)
 916 {
 917         struct request_queue *rq;
 918         struct blkfront_info *info = gd->private_data;
 919
 920         memset(&info->tag_set, 0, sizeof(info->tag_set));
 921         info->tag_set.ops = &blkfront_mq_ops;
 922         info->tag_set.nr_hw_queues = info->nr_rings;
 923         if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
 924                 /*
 925                  * When indirect descriptior is not supported, the I/O request
 926                  * will be split between multiple request in the ring.
 927                  * To avoid problems when sending the request, divide by
 928                  * 2 the depth of the queue.
 929                  */
 930                 info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
 931         } else
 932                 info->tag_set.queue_depth = BLK_RING_SIZE(info);
 933         info->tag_set.numa_node = NUMA_NO_NODE;
 934         info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
 935         info->tag_set.cmd_size = 0;
 936         info->tag_set.driver_data = info;
 937
 938         if (blk_mq_alloc_tag_set(&info->tag_set))
 939                 return -EINVAL;
 940         rq = blk_mq_init_queue(&info->tag_set);
 941         if (IS_ERR(rq)) {
 942                 blk_mq_free_tag_set(&info->tag_set);
 943                 return PTR_ERR(rq);
 944         }
 945
 946         rq->queuedata = info;
 947         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
 948
 949         if (info->feature_discard) {
 950                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
 951                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
 952                 rq->limits.discard_granularity = info->discard_granularity;
 953                 rq->limits.discard_alignment = info->discard_alignment;
 954                 if (info->feature_secdiscard)
 955                         queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, rq);
 956         }
 957
 958         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 959         blk_queue_logical_block_size(rq, sector_size);
 960         blk_queue_physical_block_size(rq, physical_sector_size);
 961         blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
 962
 963         /* Each segment in a request is up to an aligned page in size. */
 964         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 965         blk_queue_max_segment_size(rq, PAGE_SIZE);
 966
 967         /* Ensure a merged request will fit in a single I/O ring slot. */
 968         blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
 969
 970         /* Make sure buffer addresses are sector-aligned. */
 971         blk_queue_dma_alignment(rq, 511);
 972
 973         /* Make sure we don't use bounce buffers. */
 974         blk_queue_bounce_limit(rq, BLK_BOUNCE_ANY);
 975
 976         gd->queue = rq;
 977
 978         return 0;
 979 }
 980
 981 static const char *flush_info(unsigned int feature_flush)
 982 {
 983         switch (feature_flush & ((REQ_FLUSH | REQ_FUA))) {
 984         case REQ_FLUSH|REQ_FUA:
 985                 return "barrier: enabled;";
 986         case REQ_FLUSH:
 987                 return "flush diskcache: enabled;";
 988         default:
 989                 return "barrier or flush: disabled;";
 990         }
 991 }
 992
 993 static void xlvbd_flush(struct blkfront_info *info)
 994 {
 995         blk_queue_write_cache(info->rq, info->feature_flush & REQ_FLUSH,
 996                                 info->feature_flush & REQ_FUA);
 997         pr_info("blkfront: %s: %s %s %s %s %s\n",
 998                 info->gd->disk_name, flush_info(info->feature_flush),
 999                 "persistent grants:", info->feature_persistent ?
1000                 "enabled;" : "disabled;", "indirect descriptors:",
1001                 info->max_indirect_segments ? "enabled;" : "disabled;");
1002 }
1003
1004 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1005 {
1006         int major;
1007         major = BLKIF_MAJOR(vdevice);
1008         *minor = BLKIF_MINOR(vdevice);
1009         switch (major) {
1010                 case XEN_IDE0_MAJOR:
1011                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1012                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
1013                                 EMULATED_HD_DISK_MINOR_OFFSET;
1014                         break;
1015                 case XEN_IDE1_MAJOR:
1016                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1017                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1018                                 EMULATED_HD_DISK_MINOR_OFFSET;
1019                         break;
1020                 case XEN_SCSI_DISK0_MAJOR:
1021                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1022                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1023                         break;
1024                 case XEN_SCSI_DISK1_MAJOR:
1025                 case XEN_SCSI_DISK2_MAJOR:
1026                 case XEN_SCSI_DISK3_MAJOR:
1027                 case XEN_SCSI_DISK4_MAJOR:
1028                 case XEN_SCSI_DISK5_MAJOR:
1029                 case XEN_SCSI_DISK6_MAJOR:
1030                 case XEN_SCSI_DISK7_MAJOR:
1031                         *offset = (*minor / PARTS_PER_DISK) +
1032                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1033                                 EMULATED_SD_DISK_NAME_OFFSET;
1034                         *minor = *minor +
1035                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1036                                 EMULATED_SD_DISK_MINOR_OFFSET;
1037                         break;
1038                 case XEN_SCSI_DISK8_MAJOR:
1039                 case XEN_SCSI_DISK9_MAJOR:
1040                 case XEN_SCSI_DISK10_MAJOR:
1041                 case XEN_SCSI_DISK11_MAJOR:
1042                 case XEN_SCSI_DISK12_MAJOR:
1043                 case XEN_SCSI_DISK13_MAJOR:
1044                 case XEN_SCSI_DISK14_MAJOR:
1045                 case XEN_SCSI_DISK15_MAJOR:
1046                         *offset = (*minor / PARTS_PER_DISK) +
1047                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1048                                 EMULATED_SD_DISK_NAME_OFFSET;
1049                         *minor = *minor +
1050                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1051                                 EMULATED_SD_DISK_MINOR_OFFSET;
1052                         break;
1053                 case XENVBD_MAJOR:
1054                         *offset = *minor / PARTS_PER_DISK;
1055                         break;
1056                 default:
1057                         printk(KERN_WARNING "blkfront: your disk configuration is "
1058                                         "incorrect, please use an xvd device instead\n");
1059                         return -ENODEV;
1060         }
1061         return 0;
1062 }
1063
1064 static char *encode_disk_name(char *ptr, unsigned int n)
1065 {
1066         if (n >= 26)
1067                 ptr = encode_disk_name(ptr, n / 26 - 1);
1068         *ptr = 'a' + n % 26;
1069         return ptr + 1;
1070 }
1071
1072 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1073                                struct blkfront_info *info,
1074                                u16 vdisk_info, u16 sector_size,
1075                                unsigned int physical_sector_size)
1076 {
1077         struct gendisk *gd;
1078         int nr_minors = 1;
1079         int err;
1080         unsigned int offset;
1081         int minor;
1082         int nr_parts;
1083         char *ptr;
1084
1085         BUG_ON(info->gd != NULL);
1086         BUG_ON(info->rq != NULL);
1087
1088         if ((info->vdevice>>EXT_SHIFT) > 1) {
1089                 /* this is above the extended range; something is wrong */
1090                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1091                 return -ENODEV;
1092         }
1093
1094         if (!VDEV_IS_EXTENDED(info->vdevice)) {
1095                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1096                 if (err)
1097                         return err;
1098                 nr_parts = PARTS_PER_DISK;
1099         } else {
1100                 minor = BLKIF_MINOR_EXT(info->vdevice);
1101                 nr_parts = PARTS_PER_EXT_DISK;
1102                 offset = minor / nr_parts;
1103                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1104                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1105                                         "emulated IDE disks,\n\t choose an xvd device name"
1106                                         "from xvde on\n", info->vdevice);
1107         }
1108         if (minor >> MINORBITS) {
1109                 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1110                         info->vdevice, minor);
1111                 return -ENODEV;
1112         }
1113
1114         if ((minor % nr_parts) == 0)
1115                 nr_minors = nr_parts;
1116
1117         err = xlbd_reserve_minors(minor, nr_minors);
1118         if (err)
1119                 goto out;
1120         err = -ENODEV;
1121
1122         gd = alloc_disk(nr_minors);
1123         if (gd == NULL)
1124                 goto release;
1125
1126         strcpy(gd->disk_name, DEV_NAME);
1127         ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1128         BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1129         if (nr_minors > 1)
1130                 *ptr = 0;
1131         else
1132                 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1133                          "%d", minor & (nr_parts - 1));
1134
1135         gd->major = XENVBD_MAJOR;
1136         gd->first_minor = minor;
1137         gd->fops = &xlvbd_block_fops;
1138         gd->private_data = info;
1139         gd->driverfs_dev = &(info->xbdev->dev);
1140         set_capacity(gd, capacity);
1141
1142         if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size,
1143                                  info->max_indirect_segments ? :
1144                                  BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
1145                 del_gendisk(gd);
1146                 goto release;
1147         }
1148
1149         info->rq = gd->queue;
1150         info->gd = gd;
1151
1152         xlvbd_flush(info);
1153
1154         if (vdisk_info & VDISK_READONLY)
1155                 set_disk_ro(gd, 1);
1156
1157         if (vdisk_info & VDISK_REMOVABLE)
1158                 gd->flags |= GENHD_FL_REMOVABLE;
1159
1160         if (vdisk_info & VDISK_CDROM)
1161                 gd->flags |= GENHD_FL_CD;
1162
1163         return 0;
1164
1165  release:
1166         xlbd_release_minors(minor, nr_minors);
1167  out:
1168         return err;
1169 }
1170
1171 static void xlvbd_release_gendisk(struct blkfront_info *info)
1172 {
1173         unsigned int minor, nr_minors, i;
1174
1175         if (info->rq == NULL)
1176                 return;
1177
1178         /* No more blkif_request(). */
1179         blk_mq_stop_hw_queues(info->rq);
1180
1181         for (i = 0; i < info->nr_rings; i++) {
1182                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1183
1184                 /* No more gnttab callback work. */
1185                 gnttab_cancel_free_callback(&rinfo->callback);
1186
1187                 /* Flush gnttab callback work. Must be done with no locks held. */
1188                 flush_work(&rinfo->work);
1189         }
1190
1191         del_gendisk(info->gd);
1192
1193         minor = info->gd->first_minor;
1194         nr_minors = info->gd->minors;
1195         xlbd_release_minors(minor, nr_minors);
1196
1197         blk_cleanup_queue(info->rq);
1198         blk_mq_free_tag_set(&info->tag_set);
1199         info->rq = NULL;
1200
1201         put_disk(info->gd);
1202         info->gd = NULL;
1203 }
1204
1205 /* Already hold rinfo->ring_lock. */
1206 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1207 {
1208         if (!RING_FULL(&rinfo->ring))
1209                 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1210 }
1211
1212 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1213 {
1214         unsigned long flags;
1215
1216         spin_lock_irqsave(&rinfo->ring_lock, flags);
1217         kick_pending_request_queues_locked(rinfo);
1218         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1219 }
1220
1221 static void blkif_restart_queue(struct work_struct *work)
1222 {
1223         struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1224
1225         if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1226                 kick_pending_request_queues(rinfo);
1227 }
1228
1229 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1230 {
1231         struct grant *persistent_gnt, *n;
1232         struct blkfront_info *info = rinfo->dev_info;
1233         int i, j, segs;
1234
1235         /*
1236          * Remove indirect pages, this only happens when using indirect
1237          * descriptors but not persistent grants
1238          */
1239         if (!list_empty(&rinfo->indirect_pages)) {
1240                 struct page *indirect_page, *n;
1241
1242                 BUG_ON(info->feature_persistent);
1243                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1244                         list_del(&indirect_page->lru);
1245                         __free_page(indirect_page);
1246                 }
1247         }
1248
1249         /* Remove all persistent grants. */
1250         if (!list_empty(&rinfo->grants)) {
1251                 list_for_each_entry_safe(persistent_gnt, n,
1252                                          &rinfo->grants, node) {
1253                         list_del(&persistent_gnt->node);
1254                         if (persistent_gnt->gref != GRANT_INVALID_REF) {
1255                                 gnttab_end_foreign_access(persistent_gnt->gref,
1256                                                           0, 0UL);
1257                                 rinfo->persistent_gnts_c--;
1258                         }
1259                         if (info->feature_persistent)
1260                                 __free_page(persistent_gnt->page);
1261                         kfree(persistent_gnt);
1262                 }
1263         }
1264         BUG_ON(rinfo->persistent_gnts_c != 0);
1265
1266         for (i = 0; i < BLK_RING_SIZE(info); i++) {
1267                 /*
1268                  * Clear persistent grants present in requests already
1269                  * on the shared ring
1270                  */
1271                 if (!rinfo->shadow[i].request)
1272                         goto free_shadow;
1273
1274                 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1275                        rinfo->shadow[i].req.u.indirect.nr_segments :
1276                        rinfo->shadow[i].req.u.rw.nr_segments;
1277                 for (j = 0; j < segs; j++) {
1278                         persistent_gnt = rinfo->shadow[i].grants_used[j];
1279                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1280                         if (info->feature_persistent)
1281                                 __free_page(persistent_gnt->page);
1282                         kfree(persistent_gnt);
1283                 }
1284
1285                 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1286                         /*
1287                          * If this is not an indirect operation don't try to
1288                          * free indirect segments
1289                          */
1290                         goto free_shadow;
1291
1292                 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1293                         persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1294                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1295                         __free_page(persistent_gnt->page);
1296                         kfree(persistent_gnt);
1297                 }
1298
1299 free_shadow:
1300                 kfree(rinfo->shadow[i].grants_used);
1301                 rinfo->shadow[i].grants_used = NULL;
1302                 kfree(rinfo->shadow[i].indirect_grants);
1303                 rinfo->shadow[i].indirect_grants = NULL;
1304                 kfree(rinfo->shadow[i].sg);
1305                 rinfo->shadow[i].sg = NULL;
1306         }
1307
1308         /* No more gnttab callback work. */
1309         gnttab_cancel_free_callback(&rinfo->callback);
1310
1311         /* Flush gnttab callback work. Must be done with no locks held. */
1312         flush_work(&rinfo->work);
1313
1314         /* Free resources associated with old device channel. */
1315         for (i = 0; i < info->nr_ring_pages; i++) {
1316                 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1317                         gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1318                         rinfo->ring_ref[i] = GRANT_INVALID_REF;
1319                 }
1320         }
1321         free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * PAGE_SIZE));
1322         rinfo->ring.sring = NULL;
1323
1324         if (rinfo->irq)
1325                 unbind_from_irqhandler(rinfo->irq, rinfo);
1326         rinfo->evtchn = rinfo->irq = 0;
1327 }
1328
1329 static void blkif_free(struct blkfront_info *info, int suspend)
1330 {
1331         unsigned int i;
1332
1333         /* Prevent new requests being issued until we fix things up. */
1334         info->connected = suspend ?
1335                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1336         /* No more blkif_request(). */
1337         if (info->rq)
1338                 blk_mq_stop_hw_queues(info->rq);
1339
1340         for (i = 0; i < info->nr_rings; i++)
1341                 blkif_free_ring(&info->rinfo[i]);
1342
1343         kfree(info->rinfo);
1344         info->rinfo = NULL;
1345         info->nr_rings = 0;
1346 }
1347
1348 struct copy_from_grant {
1349         const struct blk_shadow *s;
1350         unsigned int grant_idx;
1351         unsigned int bvec_offset;
1352         char *bvec_data;
1353 };
1354
1355 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1356                                   unsigned int len, void *data)
1357 {
1358         struct copy_from_grant *info = data;
1359         char *shared_data;
1360         /* Convenient aliases */
1361         const struct blk_shadow *s = info->s;
1362
1363         shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1364
1365         memcpy(info->bvec_data + info->bvec_offset,
1366                shared_data + offset, len);
1367
1368         info->bvec_offset += len;
1369         info->grant_idx++;
1370
1371         kunmap_atomic(shared_data);
1372 }
1373
1374 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1375 {
1376         switch (rsp)
1377         {
1378         case BLKIF_RSP_OKAY:
1379                 return REQ_DONE;
1380         case BLKIF_RSP_EOPNOTSUPP:
1381                 return REQ_EOPNOTSUPP;
1382         case BLKIF_RSP_ERROR:
1383                 /* Fallthrough. */
1384         default:
1385                 return REQ_ERROR;
1386         }
1387 }
1388
1389 /*
1390  * Get the final status of the block request based on two ring response
1391  */
1392 static int blkif_get_final_status(enum blk_req_status s1,
1393                                   enum blk_req_status s2)
1394 {
1395         BUG_ON(s1 == REQ_WAITING);
1396         BUG_ON(s2 == REQ_WAITING);
1397
1398         if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1399                 return BLKIF_RSP_ERROR;
1400         else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1401                 return BLKIF_RSP_EOPNOTSUPP;
1402         return BLKIF_RSP_OKAY;
1403 }
1404
1405 static bool blkif_completion(unsigned long *id,
1406                              struct blkfront_ring_info *rinfo,
1407                              struct blkif_response *bret)
1408 {
1409         int i = 0;
1410         struct scatterlist *sg;
1411         int num_sg, num_grant;
1412         struct blkfront_info *info = rinfo->dev_info;
1413         struct blk_shadow *s = &rinfo->shadow[*id];
1414         struct copy_from_grant data = {
1415                 .grant_idx = 0,
1416         };
1417
1418         num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1419                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1420
1421         /* The I/O request may be split in two. */
1422         if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1423                 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1424
1425                 /* Keep the status of the current response in shadow. */
1426                 s->status = blkif_rsp_to_req_status(bret->status);
1427
1428                 /* Wait the second response if not yet here. */
1429                 if (s2->status == REQ_WAITING)
1430                         return 0;
1431
1432                 bret->status = blkif_get_final_status(s->status,
1433                                                       s2->status);
1434
1435                 /*
1436                  * All the grants is stored in the first shadow in order
1437                  * to make the completion code simpler.
1438                  */
1439                 num_grant += s2->req.u.rw.nr_segments;
1440
1441                 /*
1442                  * The two responses may not come in order. Only the
1443                  * first request will store the scatter-gather list.
1444                  */
1445                 if (s2->num_sg != 0) {
1446                         /* Update "id" with the ID of the first response. */
1447                         *id = s->associated_id;
1448                         s = s2;
1449                 }
1450
1451                 /*
1452                  * We don't need anymore the second request, so recycling
1453                  * it now.
1454                  */
1455                 if (add_id_to_freelist(rinfo, s->associated_id))
1456                         WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1457                              info->gd->disk_name, s->associated_id);
1458         }
1459
1460         data.s = s;
1461         num_sg = s->num_sg;
1462
1463         if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1464                 for_each_sg(s->sg, sg, num_sg, i) {
1465                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1466
1467                         data.bvec_offset = sg->offset;
1468                         data.bvec_data = kmap_atomic(sg_page(sg));
1469
1470                         gnttab_foreach_grant_in_range(sg_page(sg),
1471                                                       sg->offset,
1472                                                       sg->length,
1473                                                       blkif_copy_from_grant,
1474                                                       &data);
1475
1476                         kunmap_atomic(data.bvec_data);
1477                 }
1478         }
1479         /* Add the persistent grant into the list of free grants */
1480         for (i = 0; i < num_grant; i++) {
1481                 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1482                         /*
1483                          * If the grant is still mapped by the backend (the
1484                          * backend has chosen to make this grant persistent)
1485                          * we add it at the head of the list, so it will be
1486                          * reused first.
1487                          */
1488                         if (!info->feature_persistent)
1489                                 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1490                                                      s->grants_used[i]->gref);
1491                         list_add(&s->grants_used[i]->node, &rinfo->grants);
1492                         rinfo->persistent_gnts_c++;
1493                 } else {
1494                         /*
1495                          * If the grant is not mapped by the backend we end the
1496                          * foreign access and add it to the tail of the list,
1497                          * so it will not be picked again unless we run out of
1498                          * persistent grants.
1499                          */
1500                         gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1501                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1502                         list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1503                 }
1504         }
1505         if (s->req.operation == BLKIF_OP_INDIRECT) {
1506                 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1507                         if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1508                                 if (!info->feature_persistent)
1509                                         pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1510                                                              s->indirect_grants[i]->gref);
1511                                 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1512                                 rinfo->persistent_gnts_c++;
1513                         } else {
1514                                 struct page *indirect_page;
1515
1516                                 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1517                                 /*
1518                                  * Add the used indirect page back to the list of
1519                                  * available pages for indirect grefs.
1520                                  */
1521                                 if (!info->feature_persistent) {
1522                                         indirect_page = s->indirect_grants[i]->page;
1523                                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
1524                                 }
1525                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1526                                 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1527                         }
1528                 }
1529         }
1530
1531         return 1;
1532 }
1533
1534 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1535 {
1536         struct request *req;
1537         struct blkif_response *bret;
1538         RING_IDX i, rp;
1539         unsigned long flags;
1540         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1541         struct blkfront_info *info = rinfo->dev_info;
1542         int error;
1543
1544         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1545                 return IRQ_HANDLED;
1546
1547         spin_lock_irqsave(&rinfo->ring_lock, flags);
1548  again:
1549         rp = rinfo->ring.sring->rsp_prod;
1550         rmb(); /* Ensure we see queued responses up to 'rp'. */
1551
1552         for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1553                 unsigned long id;
1554
1555                 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1556                 id   = bret->id;
1557                 /*
1558                  * The backend has messed up and given us an id that we would
1559                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1560                  * look in get_id_from_freelist.
1561                  */
1562                 if (id >= BLK_RING_SIZE(info)) {
1563                         WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1564                              info->gd->disk_name, op_name(bret->operation), id);
1565                         /* We can't safely get the 'struct request' as
1566                          * the id is busted. */
1567                         continue;
1568                 }
1569                 req  = rinfo->shadow[id].request;
1570
1571                 if (bret->operation != BLKIF_OP_DISCARD) {
1572                         /*
1573                          * We may need to wait for an extra response if the
1574                          * I/O request is split in 2
1575                          */
1576                         if (!blkif_completion(&id, rinfo, bret))
1577                                 continue;
1578                 }
1579
1580                 if (add_id_to_freelist(rinfo, id)) {
1581                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1582                              info->gd->disk_name, op_name(bret->operation), id);
1583                         continue;
1584                 }
1585
1586                 error = (bret->status == BLKIF_RSP_OKAY) ? 0 : -EIO;
1587                 switch (bret->operation) {
1588                 case BLKIF_OP_DISCARD:
1589                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1590                                 struct request_queue *rq = info->rq;
1591                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1592                                            info->gd->disk_name, op_name(bret->operation));
1593                                 error = -EOPNOTSUPP;
1594                                 info->feature_discard = 0;
1595                                 info->feature_secdiscard = 0;
1596                                 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1597                                 queue_flag_clear(QUEUE_FLAG_SECDISCARD, rq);
1598                         }
1599                         blk_mq_complete_request(req, error);
1600                         break;
1601                 case BLKIF_OP_FLUSH_DISKCACHE:
1602                 case BLKIF_OP_WRITE_BARRIER:
1603                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1604                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1605                                        info->gd->disk_name, op_name(bret->operation));
1606                                 error = -EOPNOTSUPP;
1607                         }
1608                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1609                                      rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1610                                 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1611                                        info->gd->disk_name, op_name(bret->operation));
1612                                 error = -EOPNOTSUPP;
1613                         }
1614                         if (unlikely(error)) {
1615                                 if (error == -EOPNOTSUPP)
1616                                         error = 0;
1617                                 info->feature_flush = 0;
1618                                 xlvbd_flush(info);
1619                         }
1620                         /* fall through */
1621                 case BLKIF_OP_READ:
1622                 case BLKIF_OP_WRITE:
1623                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
1624                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1625                                         "request: %x\n", bret->status);
1626
1627                         blk_mq_complete_request(req, error);
1628                         break;
1629                 default:
1630                         BUG();
1631                 }
1632         }
1633
1634         rinfo->ring.rsp_cons = i;
1635
1636         if (i != rinfo->ring.req_prod_pvt) {
1637                 int more_to_do;
1638                 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1639                 if (more_to_do)
1640                         goto again;
1641         } else
1642                 rinfo->ring.sring->rsp_event = i + 1;
1643
1644         kick_pending_request_queues_locked(rinfo);
1645
1646         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1647
1648         return IRQ_HANDLED;
1649 }
1650
1651
1652 static int setup_blkring(struct xenbus_device *dev,
1653                          struct blkfront_ring_info *rinfo)
1654 {
1655         struct blkif_sring *sring;
1656         int err, i;
1657         struct blkfront_info *info = rinfo->dev_info;
1658         unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1659         grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1660
1661         for (i = 0; i < info->nr_ring_pages; i++)
1662                 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1663
1664         sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1665                                                        get_order(ring_size));
1666         if (!sring) {
1667                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1668                 return -ENOMEM;
1669         }
1670         SHARED_RING_INIT(sring);
1671         FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1672
1673         err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1674         if (err < 0) {
1675                 free_pages((unsigned long)sring, get_order(ring_size));
1676                 rinfo->ring.sring = NULL;
1677                 goto fail;
1678         }
1679         for (i = 0; i < info->nr_ring_pages; i++)
1680                 rinfo->ring_ref[i] = gref[i];
1681
1682         err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1683         if (err)
1684                 goto fail;
1685
1686         err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1687                                         "blkif", rinfo);
1688         if (err <= 0) {
1689                 xenbus_dev_fatal(dev, err,
1690                                  "bind_evtchn_to_irqhandler failed");
1691                 goto fail;
1692         }
1693         rinfo->irq = err;
1694
1695         return 0;
1696 fail:
1697         blkif_free(info, 0);
1698         return err;
1699 }
1700
1701 /*
1702  * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1703  * ring buffer may have multi pages depending on ->nr_ring_pages.
1704  */
1705 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1706                                 struct blkfront_ring_info *rinfo, const char *dir)
1707 {
1708         int err;
1709         unsigned int i;
1710         const char *message = NULL;
1711         struct blkfront_info *info = rinfo->dev_info;
1712
1713         if (info->nr_ring_pages == 1) {
1714                 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1715                 if (err) {
1716                         message = "writing ring-ref";
1717                         goto abort_transaction;
1718                 }
1719         } else {
1720                 for (i = 0; i < info->nr_ring_pages; i++) {
1721                         char ring_ref_name[RINGREF_NAME_LEN];
1722
1723                         snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1724                         err = xenbus_printf(xbt, dir, ring_ref_name,
1725                                             "%u", rinfo->ring_ref[i]);
1726                         if (err) {
1727                                 message = "writing ring-ref";
1728                                 goto abort_transaction;
1729                         }
1730                 }
1731         }
1732
1733         err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1734         if (err) {
1735                 message = "writing event-channel";
1736                 goto abort_transaction;
1737         }
1738
1739         return 0;
1740
1741 abort_transaction:
1742         xenbus_transaction_end(xbt, 1);
1743         if (message)
1744                 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1745
1746         return err;
1747 }
1748
1749 /* Common code used when first setting up, and when resuming. */
1750 static int talk_to_blkback(struct xenbus_device *dev,
1751                            struct blkfront_info *info)
1752 {
1753         const char *message = NULL;
1754         struct xenbus_transaction xbt;
1755         int err;
1756         unsigned int i, max_page_order = 0;
1757         unsigned int ring_page_order = 0;
1758
1759         err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1760                            "max-ring-page-order", "%u", &max_page_order);
1761         if (err != 1)
1762                 info->nr_ring_pages = 1;
1763         else {
1764                 ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1765                 info->nr_ring_pages = 1 << ring_page_order;
1766         }
1767
1768         for (i = 0; i < info->nr_rings; i++) {
1769                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1770
1771                 /* Create shared ring, alloc event channel. */
1772                 err = setup_blkring(dev, rinfo);
1773                 if (err)
1774                         goto destroy_blkring;
1775         }
1776
1777 again:
1778         err = xenbus_transaction_start(&xbt);
1779         if (err) {
1780                 xenbus_dev_fatal(dev, err, "starting transaction");
1781                 goto destroy_blkring;
1782         }
1783
1784         if (info->nr_ring_pages > 1) {
1785                 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1786                                     ring_page_order);
1787                 if (err) {
1788                         message = "writing ring-page-order";
1789                         goto abort_transaction;
1790                 }
1791         }
1792
1793         /* We already got the number of queues/rings in _probe */
1794         if (info->nr_rings == 1) {
1795                 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1796                 if (err)
1797                         goto destroy_blkring;
1798         } else {
1799                 char *path;
1800                 size_t pathsize;
1801
1802                 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1803                                     info->nr_rings);
1804                 if (err) {
1805                         message = "writing multi-queue-num-queues";
1806                         goto abort_transaction;
1807                 }
1808
1809                 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1810                 path = kmalloc(pathsize, GFP_KERNEL);
1811                 if (!path) {
1812                         err = -ENOMEM;
1813                         message = "ENOMEM while writing ring references";
1814                         goto abort_transaction;
1815                 }
1816
1817                 for (i = 0; i < info->nr_rings; i++) {
1818                         memset(path, 0, pathsize);
1819                         snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1820                         err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1821                         if (err) {
1822                                 kfree(path);
1823                                 goto destroy_blkring;
1824                         }
1825                 }
1826                 kfree(path);
1827         }
1828         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1829                             XEN_IO_PROTO_ABI_NATIVE);
1830         if (err) {
1831                 message = "writing protocol";
1832                 goto abort_transaction;
1833         }
1834         err = xenbus_printf(xbt, dev->nodename,
1835                             "feature-persistent", "%u", 1);
1836         if (err)
1837                 dev_warn(&dev->dev,
1838                          "writing persistent grants feature to xenbus");
1839
1840         err = xenbus_transaction_end(xbt, 0);
1841         if (err) {
1842                 if (err == -EAGAIN)
1843                         goto again;
1844                 xenbus_dev_fatal(dev, err, "completing transaction");
1845                 goto destroy_blkring;
1846         }
1847
1848         for (i = 0; i < info->nr_rings; i++) {
1849                 unsigned int j;
1850                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1851
1852                 for (j = 0; j < BLK_RING_SIZE(info); j++)
1853                         rinfo->shadow[j].req.u.rw.id = j + 1;
1854                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1855         }
1856         xenbus_switch_state(dev, XenbusStateInitialised);
1857
1858         return 0;
1859
1860  abort_transaction:
1861         xenbus_transaction_end(xbt, 1);
1862         if (message)
1863                 xenbus_dev_fatal(dev, err, "%s", message);
1864  destroy_blkring:
1865         blkif_free(info, 0);
1866
1867         kfree(info);
1868         dev_set_drvdata(&dev->dev, NULL);
1869
1870         return err;
1871 }
1872
1873 static int negotiate_mq(struct blkfront_info *info)
1874 {
1875         unsigned int backend_max_queues = 0;
1876         int err;
1877         unsigned int i;
1878
1879         BUG_ON(info->nr_rings);
1880
1881         /* Check if backend supports multiple queues. */
1882         err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
1883                            "multi-queue-max-queues", "%u", &backend_max_queues);
1884         if (err < 0)
1885                 backend_max_queues = 1;
1886
1887         info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1888         /* We need at least one ring. */
1889         if (!info->nr_rings)
1890                 info->nr_rings = 1;
1891
1892         info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
1893         if (!info->rinfo) {
1894                 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1895                 return -ENOMEM;
1896         }
1897
1898         for (i = 0; i < info->nr_rings; i++) {
1899                 struct blkfront_ring_info *rinfo;
1900
1901                 rinfo = &info->rinfo[i];
1902                 INIT_LIST_HEAD(&rinfo->indirect_pages);
1903                 INIT_LIST_HEAD(&rinfo->grants);
1904                 rinfo->dev_info = info;
1905                 INIT_WORK(&rinfo->work, blkif_restart_queue);
1906                 spin_lock_init(&rinfo->ring_lock);
1907         }
1908         return 0;
1909 }
1910 /**
1911  * Entry point to this code when a new device is created.  Allocate the basic
1912  * structures and the ring buffer for communication with the backend, and
1913  * inform the backend of the appropriate details for those.  Switch to
1914  * Initialised state.
1915  */
1916 static int blkfront_probe(struct xenbus_device *dev,
1917                           const struct xenbus_device_id *id)
1918 {
1919         int err, vdevice;
1920         struct blkfront_info *info;
1921
1922         /* FIXME: Use dynamic device id if this is not set. */
1923         err = xenbus_scanf(XBT_NIL, dev->nodename,
1924                            "virtual-device", "%i", &vdevice);
1925         if (err != 1) {
1926                 /* go looking in the extended area instead */
1927                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1928                                    "%i", &vdevice);
1929                 if (err != 1) {
1930                         xenbus_dev_fatal(dev, err, "reading virtual-device");
1931                         return err;
1932                 }
1933         }
1934
1935         if (xen_hvm_domain()) {
1936                 char *type;
1937                 int len;
1938                 /* no unplug has been done: do not hook devices != xen vbds */
1939                 if (xen_has_pv_and_legacy_disk_devices()) {
1940                         int major;
1941
1942                         if (!VDEV_IS_EXTENDED(vdevice))
1943                                 major = BLKIF_MAJOR(vdevice);
1944                         else
1945                                 major = XENVBD_MAJOR;
1946
1947                         if (major != XENVBD_MAJOR) {
1948                                 printk(KERN_INFO
1949                                                 "%s: HVM does not support vbd %d as xen block device\n",
1950                                                 __func__, vdevice);
1951                                 return -ENODEV;
1952                         }
1953                 }
1954                 /* do not create a PV cdrom device if we are an HVM guest */
1955                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1956                 if (IS_ERR(type))
1957                         return -ENODEV;
1958                 if (strncmp(type, "cdrom", 5) == 0) {
1959                         kfree(type);
1960                         return -ENODEV;
1961                 }
1962                 kfree(type);
1963         }
1964         info = kzalloc(sizeof(*info), GFP_KERNEL);
1965         if (!info) {
1966                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1967                 return -ENOMEM;
1968         }
1969
1970         info->xbdev = dev;
1971         err = negotiate_mq(info);
1972         if (err) {
1973                 kfree(info);
1974                 return err;
1975         }
1976
1977         mutex_init(&info->mutex);
1978         info->vdevice = vdevice;
1979         info->connected = BLKIF_STATE_DISCONNECTED;
1980
1981         /* Front end dir is a number, which is used as the id. */
1982         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1983         dev_set_drvdata(&dev->dev, info);
1984
1985         return 0;
1986 }
1987
1988 static void split_bio_end(struct bio *bio)
1989 {
1990         struct split_bio *split_bio = bio->bi_private;
1991
1992         if (atomic_dec_and_test(&split_bio->pending)) {
1993                 split_bio->bio->bi_phys_segments = 0;
1994                 split_bio->bio->bi_error = bio->bi_error;
1995                 bio_endio(split_bio->bio);
1996                 kfree(split_bio);
1997         }
1998         bio_put(bio);
1999 }
2000
2001 static int blkif_recover(struct blkfront_info *info)
2002 {
2003         unsigned int i, r_index;
2004         struct request *req, *n;
2005         struct blk_shadow *copy;
2006         int rc;
2007         struct bio *bio, *cloned_bio;
2008         struct bio_list bio_list, merge_bio;
2009         unsigned int segs, offset;
2010         int pending, size;
2011         struct split_bio *split_bio;
2012         struct list_head requests;
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         bio_list_init(&bio_list);
2018         INIT_LIST_HEAD(&requests);
2019
2020         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2021                 struct blkfront_ring_info *rinfo;
2022
2023                 rinfo = &info->rinfo[r_index];
2024                 /* Stage 1: Make a safe copy of the shadow state. */
2025                 copy = kmemdup(rinfo->shadow, sizeof(rinfo->shadow),
2026                                GFP_NOIO | __GFP_REPEAT | __GFP_HIGH);
2027                 if (!copy)
2028                         return -ENOMEM;
2029
2030                 /* Stage 2: Set up free list. */
2031                 memset(&rinfo->shadow, 0, sizeof(rinfo->shadow));
2032                 for (i = 0; i < BLK_RING_SIZE(info); i++)
2033                         rinfo->shadow[i].req.u.rw.id = i+1;
2034                 rinfo->shadow_free = rinfo->ring.req_prod_pvt;
2035                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
2036
2037                 rc = blkfront_setup_indirect(rinfo);
2038                 if (rc) {
2039                         kfree(copy);
2040                         return rc;
2041                 }
2042
2043                 for (i = 0; i < BLK_RING_SIZE(info); i++) {
2044                         /* Not in use? */
2045                         if (!copy[i].request)
2046                                 continue;
2047
2048                         /*
2049                          * Get the bios in the request so we can re-queue them.
2050                          */
2051                         if (copy[i].request->cmd_flags &
2052                             (REQ_FLUSH | REQ_FUA | REQ_DISCARD | REQ_SECURE)) {
2053                                 /*
2054                                  * Flush operations don't contain bios, so
2055                                  * we need to requeue the whole request
2056                                  */
2057                                 list_add(&copy[i].request->queuelist, &requests);
2058                                 continue;
2059                         }
2060                         merge_bio.head = copy[i].request->bio;
2061                         merge_bio.tail = copy[i].request->biotail;
2062                         bio_list_merge(&bio_list, &merge_bio);
2063                         copy[i].request->bio = NULL;
2064                         blk_end_request_all(copy[i].request, 0);
2065                 }
2066
2067                 kfree(copy);
2068         }
2069         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2070
2071         /* Now safe for us to use the shared ring */
2072         info->connected = BLKIF_STATE_CONNECTED;
2073
2074         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2075                 struct blkfront_ring_info *rinfo;
2076
2077                 rinfo = &info->rinfo[r_index];
2078                 /* Kick any other new requests queued since we resumed */
2079                 kick_pending_request_queues(rinfo);
2080         }
2081
2082         list_for_each_entry_safe(req, n, &requests, queuelist) {
2083                 /* Requeue pending requests (flush or discard) */
2084                 list_del_init(&req->queuelist);
2085                 BUG_ON(req->nr_phys_segments > segs);
2086                 blk_mq_requeue_request(req);
2087         }
2088         blk_mq_kick_requeue_list(info->rq);
2089
2090         while ((bio = bio_list_pop(&bio_list)) != NULL) {
2091                 /* Traverse the list of pending bios and re-queue them */
2092                 if (bio_segments(bio) > segs) {
2093                         /*
2094                          * This bio has more segments than what we can
2095                          * handle, we have to split it.
2096                          */
2097                         pending = (bio_segments(bio) + segs - 1) / segs;
2098                         split_bio = kzalloc(sizeof(*split_bio), GFP_NOIO);
2099                         BUG_ON(split_bio == NULL);
2100                         atomic_set(&split_bio->pending, pending);
2101                         split_bio->bio = bio;
2102                         for (i = 0; i < pending; i++) {
2103                                 offset = (i * segs * XEN_PAGE_SIZE) >> 9;
2104                                 size = min((unsigned int)(segs * XEN_PAGE_SIZE) >> 9,
2105                                            (unsigned int)bio_sectors(bio) - offset);
2106                                 cloned_bio = bio_clone(bio, GFP_NOIO);
2107                                 BUG_ON(cloned_bio == NULL);
2108                                 bio_trim(cloned_bio, offset, size);
2109                                 cloned_bio->bi_private = split_bio;
2110                                 cloned_bio->bi_end_io = split_bio_end;
2111                                 submit_bio(cloned_bio->bi_rw, cloned_bio);
2112                         }
2113                         /*
2114                          * Now we have to wait for all those smaller bios to
2115                          * end, so we can also end the "parent" bio.
2116                          */
2117                         continue;
2118                 }
2119                 /* We don't need to split this bio */
2120                 submit_bio(bio->bi_rw, bio);
2121         }
2122
2123         return 0;
2124 }
2125
2126 /**
2127  * We are reconnecting to the backend, due to a suspend/resume, or a backend
2128  * driver restart.  We tear down our blkif structure and recreate it, but
2129  * leave the device-layer structures intact so that this is transparent to the
2130  * rest of the kernel.
2131  */
2132 static int blkfront_resume(struct xenbus_device *dev)
2133 {
2134         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2135         int err = 0;
2136
2137         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2138
2139         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2140
2141         err = negotiate_mq(info);
2142         if (err)
2143                 return err;
2144
2145         err = talk_to_blkback(dev, info);
2146         if (!err)
2147                 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2148
2149         /*
2150          * We have to wait for the backend to switch to
2151          * connected state, since we want to read which
2152          * features it supports.
2153          */
2154
2155         return err;
2156 }
2157
2158 static void blkfront_closing(struct blkfront_info *info)
2159 {
2160         struct xenbus_device *xbdev = info->xbdev;
2161         struct block_device *bdev = NULL;
2162
2163         mutex_lock(&info->mutex);
2164
2165         if (xbdev->state == XenbusStateClosing) {
2166                 mutex_unlock(&info->mutex);
2167                 return;
2168         }
2169
2170         if (info->gd)
2171                 bdev = bdget_disk(info->gd, 0);
2172
2173         mutex_unlock(&info->mutex);
2174
2175         if (!bdev) {
2176                 xenbus_frontend_closed(xbdev);
2177                 return;
2178         }
2179
2180         mutex_lock(&bdev->bd_mutex);
2181
2182         if (bdev->bd_openers) {
2183                 xenbus_dev_error(xbdev, -EBUSY,
2184                                  "Device in use; refusing to close");
2185                 xenbus_switch_state(xbdev, XenbusStateClosing);
2186         } else {
2187                 xlvbd_release_gendisk(info);
2188                 xenbus_frontend_closed(xbdev);
2189         }
2190
2191         mutex_unlock(&bdev->bd_mutex);
2192         bdput(bdev);
2193 }
2194
2195 static void blkfront_setup_discard(struct blkfront_info *info)
2196 {
2197         int err;
2198         unsigned int discard_granularity;
2199         unsigned int discard_alignment;
2200         unsigned int discard_secure;
2201
2202         info->feature_discard = 1;
2203         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2204                 "discard-granularity", "%u", &discard_granularity,
2205                 "discard-alignment", "%u", &discard_alignment,
2206                 NULL);
2207         if (!err) {
2208                 info->discard_granularity = discard_granularity;
2209                 info->discard_alignment = discard_alignment;
2210         }
2211         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2212                     "discard-secure", "%d", &discard_secure,
2213                     NULL);
2214         if (!err)
2215                 info->feature_secdiscard = !!discard_secure;
2216 }
2217
2218 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2219 {
2220         unsigned int psegs, grants;
2221         int err, i;
2222         struct blkfront_info *info = rinfo->dev_info;
2223
2224         if (info->max_indirect_segments == 0) {
2225                 if (!HAS_EXTRA_REQ)
2226                         grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2227                 else {
2228                         /*
2229                          * When an extra req is required, the maximum
2230                          * grants supported is related to the size of the
2231                          * Linux block segment.
2232                          */
2233                         grants = GRANTS_PER_PSEG;
2234                 }
2235         }
2236         else
2237                 grants = info->max_indirect_segments;
2238         psegs = grants / GRANTS_PER_PSEG;
2239
2240         err = fill_grant_buffer(rinfo,
2241                                 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2242         if (err)
2243                 goto out_of_memory;
2244
2245         if (!info->feature_persistent && info->max_indirect_segments) {
2246                 /*
2247                  * We are using indirect descriptors but not persistent
2248                  * grants, we need to allocate a set of pages that can be
2249                  * used for mapping indirect grefs
2250                  */
2251                 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2252
2253                 BUG_ON(!list_empty(&rinfo->indirect_pages));
2254                 for (i = 0; i < num; i++) {
2255                         struct page *indirect_page = alloc_page(GFP_NOIO);
2256                         if (!indirect_page)
2257                                 goto out_of_memory;
2258                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
2259                 }
2260         }
2261
2262         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2263                 rinfo->shadow[i].grants_used = kzalloc(
2264                         sizeof(rinfo->shadow[i].grants_used[0]) * grants,
2265                         GFP_NOIO);
2266                 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO);
2267                 if (info->max_indirect_segments)
2268                         rinfo->shadow[i].indirect_grants = kzalloc(
2269                                 sizeof(rinfo->shadow[i].indirect_grants[0]) *
2270                                 INDIRECT_GREFS(grants),
2271                                 GFP_NOIO);
2272                 if ((rinfo->shadow[i].grants_used == NULL) ||
2273                         (rinfo->shadow[i].sg == NULL) ||
2274                      (info->max_indirect_segments &&
2275                      (rinfo->shadow[i].indirect_grants == NULL)))
2276                         goto out_of_memory;
2277                 sg_init_table(rinfo->shadow[i].sg, psegs);
2278         }
2279
2280
2281         return 0;
2282
2283 out_of_memory:
2284         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2285                 kfree(rinfo->shadow[i].grants_used);
2286                 rinfo->shadow[i].grants_used = NULL;
2287                 kfree(rinfo->shadow[i].sg);
2288                 rinfo->shadow[i].sg = NULL;
2289                 kfree(rinfo->shadow[i].indirect_grants);
2290                 rinfo->shadow[i].indirect_grants = NULL;
2291         }
2292         if (!list_empty(&rinfo->indirect_pages)) {
2293                 struct page *indirect_page, *n;
2294                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2295                         list_del(&indirect_page->lru);
2296                         __free_page(indirect_page);
2297                 }
2298         }
2299         return -ENOMEM;
2300 }
2301
2302 /*
2303  * Gather all backend feature-*
2304  */
2305 static void blkfront_gather_backend_features(struct blkfront_info *info)
2306 {
2307         int err;
2308         int barrier, flush, discard, persistent;
2309         unsigned int indirect_segments;
2310
2311         info->feature_flush = 0;
2312
2313         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2314                         "feature-barrier", "%d", &barrier,
2315                         NULL);
2316
2317         /*
2318          * If there's no "feature-barrier" defined, then it means
2319          * we're dealing with a very old backend which writes
2320          * synchronously; nothing to do.
2321          *
2322          * If there are barriers, then we use flush.
2323          */
2324         if (!err && barrier)
2325                 info->feature_flush = REQ_FLUSH | REQ_FUA;
2326         /*
2327          * And if there is "feature-flush-cache" use that above
2328          * barriers.
2329          */
2330         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2331                         "feature-flush-cache", "%d", &flush,
2332                         NULL);
2333
2334         if (!err && flush)
2335                 info->feature_flush = REQ_FLUSH;
2336
2337         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2338                         "feature-discard", "%d", &discard,
2339                         NULL);
2340
2341         if (!err && discard)
2342                 blkfront_setup_discard(info);
2343
2344         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2345                         "feature-persistent", "%u", &persistent,
2346                         NULL);
2347         if (err)
2348                 info->feature_persistent = 0;
2349         else
2350                 info->feature_persistent = persistent;
2351
2352         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2353                             "feature-max-indirect-segments", "%u", &indirect_segments,
2354                             NULL);
2355         if (err)
2356                 info->max_indirect_segments = 0;
2357         else
2358                 info->max_indirect_segments = min(indirect_segments,
2359                                                   xen_blkif_max_segments);
2360 }
2361
2362 /*
2363  * Invoked when the backend is finally 'ready' (and has told produced
2364  * the details about the physical device - #sectors, size, etc).
2365  */
2366 static void blkfront_connect(struct blkfront_info *info)
2367 {
2368         unsigned long long sectors;
2369         unsigned long sector_size;
2370         unsigned int physical_sector_size;
2371         unsigned int binfo;
2372         int err, i;
2373
2374         switch (info->connected) {
2375         case BLKIF_STATE_CONNECTED:
2376                 /*
2377                  * Potentially, the back-end may be signalling
2378                  * a capacity change; update the capacity.
2379                  */
2380                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2381                                    "sectors", "%Lu", &sectors);
2382                 if (XENBUS_EXIST_ERR(err))
2383                         return;
2384                 printk(KERN_INFO "Setting capacity to %Lu\n",
2385                        sectors);
2386                 set_capacity(info->gd, sectors);
2387                 revalidate_disk(info->gd);
2388
2389                 return;
2390         case BLKIF_STATE_SUSPENDED:
2391                 /*
2392                  * If we are recovering from suspension, we need to wait
2393                  * for the backend to announce it's features before
2394                  * reconnecting, at least we need to know if the backend
2395                  * supports indirect descriptors, and how many.
2396                  */
2397                 blkif_recover(info);
2398                 return;
2399
2400         default:
2401                 break;
2402         }
2403
2404         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2405                 __func__, info->xbdev->otherend);
2406
2407         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2408                             "sectors", "%llu", &sectors,
2409                             "info", "%u", &binfo,
2410                             "sector-size", "%lu", &sector_size,
2411                             NULL);
2412         if (err) {
2413                 xenbus_dev_fatal(info->xbdev, err,
2414                                  "reading backend fields at %s",
2415                                  info->xbdev->otherend);
2416                 return;
2417         }
2418
2419         /*
2420          * physcial-sector-size is a newer field, so old backends may not
2421          * provide this. Assume physical sector size to be the same as
2422          * sector_size in that case.
2423          */
2424         err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2425                            "physical-sector-size", "%u", &physical_sector_size);
2426         if (err != 1)
2427                 physical_sector_size = sector_size;
2428
2429         blkfront_gather_backend_features(info);
2430         for (i = 0; i < info->nr_rings; i++) {
2431                 err = blkfront_setup_indirect(&info->rinfo[i]);
2432                 if (err) {
2433                         xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2434                                          info->xbdev->otherend);
2435                         blkif_free(info, 0);
2436                         break;
2437                 }
2438         }
2439
2440         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2441                                   physical_sector_size);
2442         if (err) {
2443                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2444                                  info->xbdev->otherend);
2445                 return;
2446         }
2447
2448         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2449
2450         /* Kick pending requests. */
2451         info->connected = BLKIF_STATE_CONNECTED;
2452         for (i = 0; i < info->nr_rings; i++)
2453                 kick_pending_request_queues(&info->rinfo[i]);
2454
2455         add_disk(info->gd);
2456
2457         info->is_ready = 1;
2458 }
2459
2460 /**
2461  * Callback received when the backend's state changes.
2462  */
2463 static void blkback_changed(struct xenbus_device *dev,
2464                             enum xenbus_state backend_state)
2465 {
2466         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2467
2468         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2469
2470         switch (backend_state) {
2471         case XenbusStateInitWait:
2472                 if (dev->state != XenbusStateInitialising)
2473                         break;
2474                 if (talk_to_blkback(dev, info))
2475                         break;
2476         case XenbusStateInitialising:
2477         case XenbusStateInitialised:
2478         case XenbusStateReconfiguring:
2479         case XenbusStateReconfigured:
2480         case XenbusStateUnknown:
2481                 break;
2482
2483         case XenbusStateConnected:
2484                 /*
2485                  * talk_to_blkback sets state to XenbusStateInitialised
2486                  * and blkfront_connect sets it to XenbusStateConnected
2487                  * (if connection went OK).
2488                  *
2489                  * If the backend (or toolstack) decides to poke at backend
2490                  * state (and re-trigger the watch by setting the state repeatedly
2491                  * to XenbusStateConnected (4)) we need to deal with this.
2492                  * This is allowed as this is used to communicate to the guest
2493                  * that the size of disk has changed!
2494                  */
2495                 if ((dev->state != XenbusStateInitialised) &&
2496                     (dev->state != XenbusStateConnected)) {
2497                         if (talk_to_blkback(dev, info))
2498                                 break;
2499                 }
2500
2501                 blkfront_connect(info);
2502                 break;
2503
2504         case XenbusStateClosed:
2505                 if (dev->state == XenbusStateClosed)
2506                         break;
2507                 /* Missed the backend's Closing state -- fallthrough */
2508         case XenbusStateClosing:
2509                 if (info)
2510                         blkfront_closing(info);
2511                 break;
2512         }
2513 }
2514
2515 static int blkfront_remove(struct xenbus_device *xbdev)
2516 {
2517         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2518         struct block_device *bdev = NULL;
2519         struct gendisk *disk;
2520
2521         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2522
2523         blkif_free(info, 0);
2524
2525         mutex_lock(&info->mutex);
2526
2527         disk = info->gd;
2528         if (disk)
2529                 bdev = bdget_disk(disk, 0);
2530
2531         info->xbdev = NULL;
2532         mutex_unlock(&info->mutex);
2533
2534         if (!bdev) {
2535                 kfree(info);
2536                 return 0;
2537         }
2538
2539         /*
2540          * The xbdev was removed before we reached the Closed
2541          * state. See if it's safe to remove the disk. If the bdev
2542          * isn't closed yet, we let release take care of it.
2543          */
2544
2545         mutex_lock(&bdev->bd_mutex);
2546         info = disk->private_data;
2547
2548         dev_warn(disk_to_dev(disk),
2549                  "%s was hot-unplugged, %d stale handles\n",
2550                  xbdev->nodename, bdev->bd_openers);
2551
2552         if (info && !bdev->bd_openers) {
2553                 xlvbd_release_gendisk(info);
2554                 disk->private_data = NULL;
2555                 kfree(info);
2556         }
2557
2558         mutex_unlock(&bdev->bd_mutex);
2559         bdput(bdev);
2560
2561         return 0;
2562 }
2563
2564 static int blkfront_is_ready(struct xenbus_device *dev)
2565 {
2566         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2567
2568         return info->is_ready && info->xbdev;
2569 }
2570
2571 static int blkif_open(struct block_device *bdev, fmode_t mode)
2572 {
2573         struct gendisk *disk = bdev->bd_disk;
2574         struct blkfront_info *info;
2575         int err = 0;
2576
2577         mutex_lock(&blkfront_mutex);
2578
2579         info = disk->private_data;
2580         if (!info) {
2581                 /* xbdev gone */
2582                 err = -ERESTARTSYS;
2583                 goto out;
2584         }
2585
2586         mutex_lock(&info->mutex);
2587
2588         if (!info->gd)
2589                 /* xbdev is closed */
2590                 err = -ERESTARTSYS;
2591
2592         mutex_unlock(&info->mutex);
2593
2594 out:
2595         mutex_unlock(&blkfront_mutex);
2596         return err;
2597 }
2598
2599 static void blkif_release(struct gendisk *disk, fmode_t mode)
2600 {
2601         struct blkfront_info *info = disk->private_data;
2602         struct block_device *bdev;
2603         struct xenbus_device *xbdev;
2604
2605         mutex_lock(&blkfront_mutex);
2606
2607         bdev = bdget_disk(disk, 0);
2608
2609         if (!bdev) {
2610                 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2611                 goto out_mutex;
2612         }
2613         if (bdev->bd_openers)
2614                 goto out;
2615
2616         /*
2617          * Check if we have been instructed to close. We will have
2618          * deferred this request, because the bdev was still open.
2619          */
2620
2621         mutex_lock(&info->mutex);
2622         xbdev = info->xbdev;
2623
2624         if (xbdev && xbdev->state == XenbusStateClosing) {
2625                 /* pending switch to state closed */
2626                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2627                 xlvbd_release_gendisk(info);
2628                 xenbus_frontend_closed(info->xbdev);
2629         }
2630
2631         mutex_unlock(&info->mutex);
2632
2633         if (!xbdev) {
2634                 /* sudden device removal */
2635                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2636                 xlvbd_release_gendisk(info);
2637                 disk->private_data = NULL;
2638                 kfree(info);
2639         }
2640
2641 out:
2642         bdput(bdev);
2643 out_mutex:
2644         mutex_unlock(&blkfront_mutex);
2645 }
2646
2647 static const struct block_device_operations xlvbd_block_fops =
2648 {
2649         .owner = THIS_MODULE,
2650         .open = blkif_open,
2651         .release = blkif_release,
2652         .getgeo = blkif_getgeo,
2653         .ioctl = blkif_ioctl,
2654 };
2655
2656
2657 static const struct xenbus_device_id blkfront_ids[] = {
2658         { "vbd" },
2659         { "" }
2660 };
2661
2662 static struct xenbus_driver blkfront_driver = {
2663         .ids  = blkfront_ids,
2664         .probe = blkfront_probe,
2665         .remove = blkfront_remove,
2666         .resume = blkfront_resume,
2667         .otherend_changed = blkback_changed,
2668         .is_ready = blkfront_is_ready,
2669 };
2670
2671 static int __init xlblk_init(void)
2672 {
2673         int ret;
2674         int nr_cpus = num_online_cpus();
2675
2676         if (!xen_domain())
2677                 return -ENODEV;
2678
2679         if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2680                 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2681                         xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2682                 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2683         }
2684
2685         if (xen_blkif_max_queues > nr_cpus) {
2686                 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2687                         xen_blkif_max_queues, nr_cpus);
2688                 xen_blkif_max_queues = nr_cpus;
2689         }
2690
2691         if (!xen_has_pv_disk_devices())
2692                 return -ENODEV;
2693
2694         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2695                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2696                        XENVBD_MAJOR, DEV_NAME);
2697                 return -ENODEV;
2698         }
2699
2700         ret = xenbus_register_frontend(&blkfront_driver);
2701         if (ret) {
2702                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2703                 return ret;
2704         }
2705
2706         return 0;
2707 }
2708 module_init(xlblk_init);
2709
2710
2711 static void __exit xlblk_exit(void)
2712 {
2713         xenbus_unregister_driver(&blkfront_driver);
2714         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2715         kfree(minors);
2716 }
2717 module_exit(xlblk_exit);
2718
2719 MODULE_DESCRIPTION("Xen virtual block device frontend");
2720 MODULE_LICENSE("GPL");
2721 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2722 MODULE_ALIAS("xen:vbd");
2723 MODULE_ALIAS("xenblk");