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