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 #include <linux/workqueue.h>
  50 #include <linux/sched/mm.h>
  51
  52 #include <xen/xen.h>
  53 #include <xen/xenbus.h>
  54 #include <xen/grant_table.h>
  55 #include <xen/events.h>
  56 #include <xen/page.h>
  57 #include <xen/platform_pci.h>
  58
  59 #include <xen/interface/grant_table.h>
  60 #include <xen/interface/io/blkif.h>
  61 #include <xen/interface/io/protocols.h>
  62
  63 #include <asm/xen/hypervisor.h>
  64
  65 /*
  66  * The minimal size of segment supported by the block framework is PAGE_SIZE.
  67  * When Linux is using a different page size than Xen, it may not be possible
  68  * to put all the data in a single segment.
  69  * This can happen when the backend doesn't support indirect descriptor and
  70  * therefore the maximum amount of data that a request can carry is
  71  * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
  72  *
  73  * Note that we only support one extra request. So the Linux page size
  74  * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
  75  * 88KB.
  76  */
  77 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
  78
  79 enum blkif_state {
  80         BLKIF_STATE_DISCONNECTED,
  81         BLKIF_STATE_CONNECTED,
  82         BLKIF_STATE_SUSPENDED,
  83         BLKIF_STATE_ERROR,
  84 };
  85
  86 struct grant {
  87         grant_ref_t gref;
  88         struct page *page;
  89         struct list_head node;
  90 };
  91
  92 enum blk_req_status {
  93         REQ_PROCESSING,
  94         REQ_WAITING,
  95         REQ_DONE,
  96         REQ_ERROR,
  97         REQ_EOPNOTSUPP,
  98 };
  99
 100 struct blk_shadow {
 101         struct blkif_request req;
 102         struct request *request;
 103         struct grant **grants_used;
 104         struct grant **indirect_grants;
 105         struct scatterlist *sg;
 106         unsigned int num_sg;
 107         enum blk_req_status status;
 108
 109         #define NO_ASSOCIATED_ID ~0UL
 110         /*
 111          * Id of the sibling if we ever need 2 requests when handling a
 112          * block I/O request
 113          */
 114         unsigned long associated_id;
 115 };
 116
 117 struct blkif_req {
 118         blk_status_t    error;
 119 };
 120
 121 static inline struct blkif_req *blkif_req(struct request *rq)
 122 {
 123         return blk_mq_rq_to_pdu(rq);
 124 }
 125
 126 static DEFINE_MUTEX(blkfront_mutex);
 127 static const struct block_device_operations xlvbd_block_fops;
 128 static struct delayed_work blkfront_work;
 129 static LIST_HEAD(info_list);
 130
 131 /*
 132  * Maximum number of segments in indirect requests, the actual value used by
 133  * the frontend driver is the minimum of this value and the value provided
 134  * by the backend driver.
 135  */
 136
 137 static unsigned int xen_blkif_max_segments = 32;
 138 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
 139 MODULE_PARM_DESC(max_indirect_segments,
 140                  "Maximum amount of segments in indirect requests (default is 32)");
 141
 142 static unsigned int xen_blkif_max_queues = 4;
 143 module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
 144 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
 145
 146 /*
 147  * Maximum order of pages to be used for the shared ring between front and
 148  * backend, 4KB page granularity is used.
 149  */
 150 static unsigned int xen_blkif_max_ring_order;
 151 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
 152 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
 153
 154 static bool __read_mostly xen_blkif_trusted = true;
 155 module_param_named(trusted, xen_blkif_trusted, bool, 0644);
 156 MODULE_PARM_DESC(trusted, "Is the backend trusted");
 157
 158 #define BLK_RING_SIZE(info)     \
 159         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
 160
 161 #define BLK_MAX_RING_SIZE       \
 162         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS)
 163
 164 /*
 165  * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
 166  * characters are enough. Define to 20 to keep consistent with backend.
 167  */
 168 #define RINGREF_NAME_LEN (20)
 169 /*
 170  * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
 171  */
 172 #define QUEUE_NAME_LEN (17)
 173
 174 /*
 175  *  Per-ring info.
 176  *  Every blkfront device can associate with one or more blkfront_ring_info,
 177  *  depending on how many hardware queues/rings to be used.
 178  */
 179 struct blkfront_ring_info {
 180         /* Lock to protect data in every ring buffer. */
 181         spinlock_t ring_lock;
 182         struct blkif_front_ring ring;
 183         unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
 184         unsigned int evtchn, irq;
 185         struct work_struct work;
 186         struct gnttab_free_callback callback;
 187         struct blk_shadow shadow[BLK_MAX_RING_SIZE];
 188         struct list_head indirect_pages;
 189         struct list_head grants;
 190         unsigned int persistent_gnts_c;
 191         unsigned long shadow_free;
 192         struct blkfront_info *dev_info;
 193 };
 194
 195 /*
 196  * We have one of these per vbd, whether ide, scsi or 'other'.  They
 197  * hang in private_data off the gendisk structure. We may end up
 198  * putting all kinds of interesting stuff here :-)
 199  */
 200 struct blkfront_info
 201 {
 202         struct mutex mutex;
 203         struct xenbus_device *xbdev;
 204         struct gendisk *gd;
 205         u16 sector_size;
 206         unsigned int physical_sector_size;
 207         int vdevice;
 208         blkif_vdev_t handle;
 209         enum blkif_state connected;
 210         /* Number of pages per ring buffer. */
 211         unsigned int nr_ring_pages;
 212         struct request_queue *rq;
 213         unsigned int feature_flush:1;
 214         unsigned int feature_fua:1;
 215         unsigned int feature_discard:1;
 216         unsigned int feature_secdiscard:1;
 217         unsigned int feature_persistent:1;
 218         unsigned int bounce:1;
 219         unsigned int discard_granularity;
 220         unsigned int discard_alignment;
 221         /* Number of 4KB segments handled */
 222         unsigned int max_indirect_segments;
 223         int is_ready;
 224         struct blk_mq_tag_set tag_set;
 225         struct blkfront_ring_info *rinfo;
 226         unsigned int nr_rings;
 227         /* Save uncomplete reqs and bios for migration. */
 228         struct list_head requests;
 229         struct bio_list bio_list;
 230         struct list_head info_list;
 231 };
 232
 233 static unsigned int nr_minors;
 234 static unsigned long *minors;
 235 static DEFINE_SPINLOCK(minor_lock);
 236
 237 #define GRANT_INVALID_REF       0
 238
 239 #define PARTS_PER_DISK          16
 240 #define PARTS_PER_EXT_DISK      256
 241
 242 #define BLKIF_MAJOR(dev) ((dev)>>8)
 243 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 244
 245 #define EXT_SHIFT 28
 246 #define EXTENDED (1<<EXT_SHIFT)
 247 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 248 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 249 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 250 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 251 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 252 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 253
 254 #define DEV_NAME        "xvd"   /* name in /dev */
 255
 256 /*
 257  * Grants are always the same size as a Xen page (i.e 4KB).
 258  * A physical segment is always the same size as a Linux page.
 259  * Number of grants per physical segment
 260  */
 261 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
 262
 263 #define GRANTS_PER_INDIRECT_FRAME \
 264         (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
 265
 266 #define INDIRECT_GREFS(_grants)         \
 267         DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
 268
 269 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 270 static void blkfront_gather_backend_features(struct blkfront_info *info);
 271 static int negotiate_mq(struct blkfront_info *info);
 272
 273 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 274 {
 275         unsigned long free = rinfo->shadow_free;
 276
 277         BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
 278         rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
 279         rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 280         return free;
 281 }
 282
 283 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
 284                               unsigned long id)
 285 {
 286         if (rinfo->shadow[id].req.u.rw.id != id)
 287                 return -EINVAL;
 288         if (rinfo->shadow[id].request == NULL)
 289                 return -EINVAL;
 290         rinfo->shadow[id].req.u.rw.id  = rinfo->shadow_free;
 291         rinfo->shadow[id].request = NULL;
 292         rinfo->shadow_free = id;
 293         return 0;
 294 }
 295
 296 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 297 {
 298         struct blkfront_info *info = rinfo->dev_info;
 299         struct page *granted_page;
 300         struct grant *gnt_list_entry, *n;
 301         int i = 0;
 302
 303         while (i < num) {
 304                 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
 305                 if (!gnt_list_entry)
 306                         goto out_of_memory;
 307
 308                 if (info->bounce) {
 309                         granted_page = alloc_page(GFP_NOIO | __GFP_ZERO);
 310                         if (!granted_page) {
 311                                 kfree(gnt_list_entry);
 312                                 goto out_of_memory;
 313                         }
 314                         gnt_list_entry->page = granted_page;
 315                 }
 316
 317                 gnt_list_entry->gref = GRANT_INVALID_REF;
 318                 list_add(&gnt_list_entry->node, &rinfo->grants);
 319                 i++;
 320         }
 321
 322         return 0;
 323
 324 out_of_memory:
 325         list_for_each_entry_safe(gnt_list_entry, n,
 326                                  &rinfo->grants, node) {
 327                 list_del(&gnt_list_entry->node);
 328                 if (info->bounce)
 329                         __free_page(gnt_list_entry->page);
 330                 kfree(gnt_list_entry);
 331                 i--;
 332         }
 333         BUG_ON(i != 0);
 334         return -ENOMEM;
 335 }
 336
 337 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
 338 {
 339         struct grant *gnt_list_entry;
 340
 341         BUG_ON(list_empty(&rinfo->grants));
 342         gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
 343                                           node);
 344         list_del(&gnt_list_entry->node);
 345
 346         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 347                 rinfo->persistent_gnts_c--;
 348
 349         return gnt_list_entry;
 350 }
 351
 352 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
 353                                         const struct blkfront_info *info)
 354 {
 355         gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
 356                                                  info->xbdev->otherend_id,
 357                                                  gnt_list_entry->page,
 358                                                  0);
 359 }
 360
 361 static struct grant *get_grant(grant_ref_t *gref_head,
 362                                unsigned long gfn,
 363                                struct blkfront_ring_info *rinfo)
 364 {
 365         struct grant *gnt_list_entry = get_free_grant(rinfo);
 366         struct blkfront_info *info = rinfo->dev_info;
 367
 368         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 369                 return gnt_list_entry;
 370
 371         /* Assign a gref to this page */
 372         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 373         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 374         if (info->bounce)
 375                 grant_foreign_access(gnt_list_entry, info);
 376         else {
 377                 /* Grant access to the GFN passed by the caller */
 378                 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
 379                                                 info->xbdev->otherend_id,
 380                                                 gfn, 0);
 381         }
 382
 383         return gnt_list_entry;
 384 }
 385
 386 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
 387                                         struct blkfront_ring_info *rinfo)
 388 {
 389         struct grant *gnt_list_entry = get_free_grant(rinfo);
 390         struct blkfront_info *info = rinfo->dev_info;
 391
 392         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 393                 return gnt_list_entry;
 394
 395         /* Assign a gref to this page */
 396         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 397         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 398         if (!info->bounce) {
 399                 struct page *indirect_page;
 400
 401                 /* Fetch a pre-allocated page to use for indirect grefs */
 402                 BUG_ON(list_empty(&rinfo->indirect_pages));
 403                 indirect_page = list_first_entry(&rinfo->indirect_pages,
 404                                                  struct page, lru);
 405                 list_del(&indirect_page->lru);
 406                 gnt_list_entry->page = indirect_page;
 407         }
 408         grant_foreign_access(gnt_list_entry, info);
 409
 410         return gnt_list_entry;
 411 }
 412
 413 static const char *op_name(int op)
 414 {
 415         static const char *const names[] = {
 416                 [BLKIF_OP_READ] = "read",
 417                 [BLKIF_OP_WRITE] = "write",
 418                 [BLKIF_OP_WRITE_BARRIER] = "barrier",
 419                 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
 420                 [BLKIF_OP_DISCARD] = "discard" };
 421
 422         if (op < 0 || op >= ARRAY_SIZE(names))
 423                 return "unknown";
 424
 425         if (!names[op])
 426                 return "reserved";
 427
 428         return names[op];
 429 }
 430 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 431 {
 432         unsigned int end = minor + nr;
 433         int rc;
 434
 435         if (end > nr_minors) {
 436                 unsigned long *bitmap, *old;
 437
 438                 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 439                                  GFP_KERNEL);
 440                 if (bitmap == NULL)
 441                         return -ENOMEM;
 442
 443                 spin_lock(&minor_lock);
 444                 if (end > nr_minors) {
 445                         old = minors;
 446                         memcpy(bitmap, minors,
 447                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 448                         minors = bitmap;
 449                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 450                 } else
 451                         old = bitmap;
 452                 spin_unlock(&minor_lock);
 453                 kfree(old);
 454         }
 455
 456         spin_lock(&minor_lock);
 457         if (find_next_bit(minors, end, minor) >= end) {
 458                 bitmap_set(minors, minor, nr);
 459                 rc = 0;
 460         } else
 461                 rc = -EBUSY;
 462         spin_unlock(&minor_lock);
 463
 464         return rc;
 465 }
 466
 467 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 468 {
 469         unsigned int end = minor + nr;
 470
 471         BUG_ON(end > nr_minors);
 472         spin_lock(&minor_lock);
 473         bitmap_clear(minors,  minor, nr);
 474         spin_unlock(&minor_lock);
 475 }
 476
 477 static void blkif_restart_queue_callback(void *arg)
 478 {
 479         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
 480         schedule_work(&rinfo->work);
 481 }
 482
 483 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 484 {
 485         /* We don't have real geometry info, but let's at least return
 486            values consistent with the size of the device */
 487         sector_t nsect = get_capacity(bd->bd_disk);
 488         sector_t cylinders = nsect;
 489
 490         hg->heads = 0xff;
 491         hg->sectors = 0x3f;
 492         sector_div(cylinders, hg->heads * hg->sectors);
 493         hg->cylinders = cylinders;
 494         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 495                 hg->cylinders = 0xffff;
 496         return 0;
 497 }
 498
 499 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 500                        unsigned command, unsigned long argument)
 501 {
 502         struct blkfront_info *info = bdev->bd_disk->private_data;
 503         int i;
 504
 505         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 506                 command, (long)argument);
 507
 508         switch (command) {
 509         case CDROMMULTISESSION:
 510                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 511                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 512                         if (put_user(0, (char __user *)(argument + i)))
 513                                 return -EFAULT;
 514                 return 0;
 515
 516         case CDROM_GET_CAPABILITY: {
 517                 struct gendisk *gd = info->gd;
 518                 if (gd->flags & GENHD_FL_CD)
 519                         return 0;
 520                 return -EINVAL;
 521         }
 522
 523         default:
 524                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 525                   command);*/
 526                 return -EINVAL; /* same return as native Linux */
 527         }
 528
 529         return 0;
 530 }
 531
 532 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 533                                             struct request *req,
 534                                             struct blkif_request **ring_req)
 535 {
 536         unsigned long id;
 537
 538         *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
 539         rinfo->ring.req_prod_pvt++;
 540
 541         id = get_id_from_freelist(rinfo);
 542         rinfo->shadow[id].request = req;
 543         rinfo->shadow[id].status = REQ_PROCESSING;
 544         rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
 545
 546         rinfo->shadow[id].req.u.rw.id = id;
 547
 548         return id;
 549 }
 550
 551 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
 552 {
 553         struct blkfront_info *info = rinfo->dev_info;
 554         struct blkif_request *ring_req, *final_ring_req;
 555         unsigned long id;
 556
 557         /* Fill out a communications ring structure. */
 558         id = blkif_ring_get_request(rinfo, req, &final_ring_req);
 559         ring_req = &rinfo->shadow[id].req;
 560
 561         ring_req->operation = BLKIF_OP_DISCARD;
 562         ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
 563         ring_req->u.discard.id = id;
 564         ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
 565         if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
 566                 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
 567         else
 568                 ring_req->u.discard.flag = 0;
 569
 570         /* Copy the request to the ring page. */
 571         *final_ring_req = *ring_req;
 572         rinfo->shadow[id].status = REQ_WAITING;
 573
 574         return 0;
 575 }
 576
 577 struct setup_rw_req {
 578         unsigned int grant_idx;
 579         struct blkif_request_segment *segments;
 580         struct blkfront_ring_info *rinfo;
 581         struct blkif_request *ring_req;
 582         grant_ref_t gref_head;
 583         unsigned int id;
 584         /* Only used when persistent grant is used and it's a read request */
 585         bool need_copy;
 586         unsigned int bvec_off;
 587         char *bvec_data;
 588
 589         bool require_extra_req;
 590         struct blkif_request *extra_ring_req;
 591 };
 592
 593 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
 594                                      unsigned int len, void *data)
 595 {
 596         struct setup_rw_req *setup = data;
 597         int n, ref;
 598         struct grant *gnt_list_entry;
 599         unsigned int fsect, lsect;
 600         /* Convenient aliases */
 601         unsigned int grant_idx = setup->grant_idx;
 602         struct blkif_request *ring_req = setup->ring_req;
 603         struct blkfront_ring_info *rinfo = setup->rinfo;
 604         /*
 605          * We always use the shadow of the first request to store the list
 606          * of grant associated to the block I/O request. This made the
 607          * completion more easy to handle even if the block I/O request is
 608          * split.
 609          */
 610         struct blk_shadow *shadow = &rinfo->shadow[setup->id];
 611
 612         if (unlikely(setup->require_extra_req &&
 613                      grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
 614                 /*
 615                  * We are using the second request, setup grant_idx
 616                  * to be the index of the segment array.
 617                  */
 618                 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
 619                 ring_req = setup->extra_ring_req;
 620         }
 621
 622         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 623             (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
 624                 if (setup->segments)
 625                         kunmap_atomic(setup->segments);
 626
 627                 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
 628                 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
 629                 shadow->indirect_grants[n] = gnt_list_entry;
 630                 setup->segments = kmap_atomic(gnt_list_entry->page);
 631                 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 632         }
 633
 634         gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
 635         ref = gnt_list_entry->gref;
 636         /*
 637          * All the grants are stored in the shadow of the first
 638          * request. Therefore we have to use the global index.
 639          */
 640         shadow->grants_used[setup->grant_idx] = gnt_list_entry;
 641
 642         if (setup->need_copy) {
 643                 void *shared_data;
 644
 645                 shared_data = kmap_atomic(gnt_list_entry->page);
 646                 /*
 647                  * this does not wipe data stored outside the
 648                  * range sg->offset..sg->offset+sg->length.
 649                  * Therefore, blkback *could* see data from
 650                  * previous requests. This is OK as long as
 651                  * persistent grants are shared with just one
 652                  * domain. It may need refactoring if this
 653                  * changes
 654                  */
 655                 memcpy(shared_data + offset,
 656                        setup->bvec_data + setup->bvec_off,
 657                        len);
 658
 659                 kunmap_atomic(shared_data);
 660                 setup->bvec_off += len;
 661         }
 662
 663         fsect = offset >> 9;
 664         lsect = fsect + (len >> 9) - 1;
 665         if (ring_req->operation != BLKIF_OP_INDIRECT) {
 666                 ring_req->u.rw.seg[grant_idx] =
 667                         (struct blkif_request_segment) {
 668                                 .gref       = ref,
 669                                 .first_sect = fsect,
 670                                 .last_sect  = lsect };
 671         } else {
 672                 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
 673                         (struct blkif_request_segment) {
 674                                 .gref       = ref,
 675                                 .first_sect = fsect,
 676                                 .last_sect  = lsect };
 677         }
 678
 679         (setup->grant_idx)++;
 680 }
 681
 682 static void blkif_setup_extra_req(struct blkif_request *first,
 683                                   struct blkif_request *second)
 684 {
 685         uint16_t nr_segments = first->u.rw.nr_segments;
 686
 687         /*
 688          * The second request is only present when the first request uses
 689          * all its segments. It's always the continuity of the first one.
 690          */
 691         first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 692
 693         second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
 694         second->u.rw.sector_number = first->u.rw.sector_number +
 695                 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
 696
 697         second->u.rw.handle = first->u.rw.handle;
 698         second->operation = first->operation;
 699 }
 700
 701 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
 702 {
 703         struct blkfront_info *info = rinfo->dev_info;
 704         struct blkif_request *ring_req, *extra_ring_req = NULL;
 705         struct blkif_request *final_ring_req, *final_extra_ring_req = NULL;
 706         unsigned long id, extra_id = NO_ASSOCIATED_ID;
 707         bool require_extra_req = false;
 708         int i;
 709         struct setup_rw_req setup = {
 710                 .grant_idx = 0,
 711                 .segments = NULL,
 712                 .rinfo = rinfo,
 713                 .need_copy = rq_data_dir(req) && info->bounce,
 714         };
 715
 716         /*
 717          * Used to store if we are able to queue the request by just using
 718          * existing persistent grants, or if we have to get new grants,
 719          * as there are not sufficiently many free.
 720          */
 721         bool new_persistent_gnts = false;
 722         struct scatterlist *sg;
 723         int num_sg, max_grefs, num_grant;
 724
 725         max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
 726         if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
 727                 /*
 728                  * If we are using indirect segments we need to account
 729                  * for the indirect grefs used in the request.
 730                  */
 731                 max_grefs += INDIRECT_GREFS(max_grefs);
 732
 733         /* Check if we have enough persistent grants to allocate a requests */
 734         if (rinfo->persistent_gnts_c < max_grefs) {
 735                 new_persistent_gnts = true;
 736
 737                 if (gnttab_alloc_grant_references(
 738                     max_grefs - rinfo->persistent_gnts_c,
 739                     &setup.gref_head) < 0) {
 740                         gnttab_request_free_callback(
 741                                 &rinfo->callback,
 742                                 blkif_restart_queue_callback,
 743                                 rinfo,
 744                                 max_grefs - rinfo->persistent_gnts_c);
 745                         return 1;
 746                 }
 747         }
 748
 749         /* Fill out a communications ring structure. */
 750         id = blkif_ring_get_request(rinfo, req, &final_ring_req);
 751         ring_req = &rinfo->shadow[id].req;
 752
 753         num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 754         num_grant = 0;
 755         /* Calculate the number of grant used */
 756         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
 757                num_grant += gnttab_count_grant(sg->offset, sg->length);
 758
 759         require_extra_req = info->max_indirect_segments == 0 &&
 760                 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
 761         BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
 762
 763         rinfo->shadow[id].num_sg = num_sg;
 764         if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
 765             likely(!require_extra_req)) {
 766                 /*
 767                  * The indirect operation can only be a BLKIF_OP_READ or
 768                  * BLKIF_OP_WRITE
 769                  */
 770                 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
 771                 ring_req->operation = BLKIF_OP_INDIRECT;
 772                 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
 773                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 774                 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
 775                 ring_req->u.indirect.handle = info->handle;
 776                 ring_req->u.indirect.nr_segments = num_grant;
 777         } else {
 778                 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 779                 ring_req->u.rw.handle = info->handle;
 780                 ring_req->operation = rq_data_dir(req) ?
 781                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 782                 if (req_op(req) == REQ_OP_FLUSH ||
 783                     (req_op(req) == REQ_OP_WRITE && (req->cmd_flags & REQ_FUA))) {
 784                         /*
 785                          * Ideally we can do an unordered flush-to-disk.
 786                          * In case the backend onlysupports barriers, use that.
 787                          * A barrier request a superset of FUA, so we can
 788                          * implement it the same way.  (It's also a FLUSH+FUA,
 789                          * since it is guaranteed ordered WRT previous writes.)
 790                          */
 791                         if (info->feature_flush && info->feature_fua)
 792                                 ring_req->operation =
 793                                         BLKIF_OP_WRITE_BARRIER;
 794                         else if (info->feature_flush)
 795                                 ring_req->operation =
 796                                         BLKIF_OP_FLUSH_DISKCACHE;
 797                         else
 798                                 ring_req->operation = 0;
 799                 }
 800                 ring_req->u.rw.nr_segments = num_grant;
 801                 if (unlikely(require_extra_req)) {
 802                         extra_id = blkif_ring_get_request(rinfo, req,
 803                                                           &final_extra_ring_req);
 804                         extra_ring_req = &rinfo->shadow[extra_id].req;
 805
 806                         /*
 807                          * Only the first request contains the scatter-gather
 808                          * list.
 809                          */
 810                         rinfo->shadow[extra_id].num_sg = 0;
 811
 812                         blkif_setup_extra_req(ring_req, extra_ring_req);
 813
 814                         /* Link the 2 requests together */
 815                         rinfo->shadow[extra_id].associated_id = id;
 816                         rinfo->shadow[id].associated_id = extra_id;
 817                 }
 818         }
 819
 820         setup.ring_req = ring_req;
 821         setup.id = id;
 822
 823         setup.require_extra_req = require_extra_req;
 824         if (unlikely(require_extra_req))
 825                 setup.extra_ring_req = extra_ring_req;
 826
 827         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
 828                 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
 829
 830                 if (setup.need_copy) {
 831                         setup.bvec_off = sg->offset;
 832                         setup.bvec_data = kmap_atomic(sg_page(sg));
 833                 }
 834
 835                 gnttab_foreach_grant_in_range(sg_page(sg),
 836                                               sg->offset,
 837                                               sg->length,
 838                                               blkif_setup_rw_req_grant,
 839                                               &setup);
 840
 841                 if (setup.need_copy)
 842                         kunmap_atomic(setup.bvec_data);
 843         }
 844         if (setup.segments)
 845                 kunmap_atomic(setup.segments);
 846
 847         /* Copy request(s) to the ring page. */
 848         *final_ring_req = *ring_req;
 849         rinfo->shadow[id].status = REQ_WAITING;
 850         if (unlikely(require_extra_req)) {
 851                 *final_extra_ring_req = *extra_ring_req;
 852                 rinfo->shadow[extra_id].status = REQ_WAITING;
 853         }
 854
 855         if (new_persistent_gnts)
 856                 gnttab_free_grant_references(setup.gref_head);
 857
 858         return 0;
 859 }
 860
 861 /*
 862  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 863  * and writes are handled as expected.
 864  *
 865  * @req: a request struct
 866  */
 867 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
 868 {
 869         if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
 870                 return 1;
 871
 872         if (unlikely(req_op(req) == REQ_OP_DISCARD ||
 873                      req_op(req) == REQ_OP_SECURE_ERASE))
 874                 return blkif_queue_discard_req(req, rinfo);
 875         else
 876                 return blkif_queue_rw_req(req, rinfo);
 877 }
 878
 879 static inline void flush_requests(struct blkfront_ring_info *rinfo)
 880 {
 881         int notify;
 882
 883         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
 884
 885         if (notify)
 886                 notify_remote_via_irq(rinfo->irq);
 887 }
 888
 889 static inline bool blkif_request_flush_invalid(struct request *req,
 890                                                struct blkfront_info *info)
 891 {
 892         return (blk_rq_is_passthrough(req) ||
 893                 ((req_op(req) == REQ_OP_FLUSH) &&
 894                  !info->feature_flush) ||
 895                 ((req->cmd_flags & REQ_FUA) &&
 896                  !info->feature_fua));
 897 }
 898
 899 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
 900                           const struct blk_mq_queue_data *qd)
 901 {
 902         unsigned long flags;
 903         int qid = hctx->queue_num;
 904         struct blkfront_info *info = hctx->queue->queuedata;
 905         struct blkfront_ring_info *rinfo = NULL;
 906
 907         BUG_ON(info->nr_rings <= qid);
 908         rinfo = &info->rinfo[qid];
 909         blk_mq_start_request(qd->rq);
 910         spin_lock_irqsave(&rinfo->ring_lock, flags);
 911         if (RING_FULL(&rinfo->ring))
 912                 goto out_busy;
 913
 914         if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
 915                 goto out_err;
 916
 917         if (blkif_queue_request(qd->rq, rinfo))
 918                 goto out_busy;
 919
 920         flush_requests(rinfo);
 921         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 922         return BLK_STS_OK;
 923
 924 out_err:
 925         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 926         return BLK_STS_IOERR;
 927
 928 out_busy:
 929         blk_mq_stop_hw_queue(hctx);
 930         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 931         return BLK_STS_DEV_RESOURCE;
 932 }
 933
 934 static void blkif_complete_rq(struct request *rq)
 935 {
 936         blk_mq_end_request(rq, blkif_req(rq)->error);
 937 }
 938
 939 static const struct blk_mq_ops blkfront_mq_ops = {
 940         .queue_rq = blkif_queue_rq,
 941         .complete = blkif_complete_rq,
 942 };
 943
 944 static void blkif_set_queue_limits(struct blkfront_info *info)
 945 {
 946         struct request_queue *rq = info->rq;
 947         struct gendisk *gd = info->gd;
 948         unsigned int segments = info->max_indirect_segments ? :
 949                                 BLKIF_MAX_SEGMENTS_PER_REQUEST;
 950
 951         blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
 952
 953         if (info->feature_discard) {
 954                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
 955                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
 956                 rq->limits.discard_granularity = info->discard_granularity ?:
 957                                                  info->physical_sector_size;
 958                 rq->limits.discard_alignment = info->discard_alignment;
 959                 if (info->feature_secdiscard)
 960                         blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
 961         }
 962
 963         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 964         blk_queue_logical_block_size(rq, info->sector_size);
 965         blk_queue_physical_block_size(rq, info->physical_sector_size);
 966         blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
 967
 968         /* Each segment in a request is up to an aligned page in size. */
 969         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 970         blk_queue_max_segment_size(rq, PAGE_SIZE);
 971
 972         /* Ensure a merged request will fit in a single I/O ring slot. */
 973         blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
 974
 975         /* Make sure buffer addresses are sector-aligned. */
 976         blk_queue_dma_alignment(rq, 511);
 977 }
 978
 979 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 980                                 unsigned int physical_sector_size)
 981 {
 982         struct request_queue *rq;
 983         struct blkfront_info *info = gd->private_data;
 984
 985         memset(&info->tag_set, 0, sizeof(info->tag_set));
 986         info->tag_set.ops = &blkfront_mq_ops;
 987         info->tag_set.nr_hw_queues = info->nr_rings;
 988         if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
 989                 /*
 990                  * When indirect descriptior is not supported, the I/O request
 991                  * will be split between multiple request in the ring.
 992                  * To avoid problems when sending the request, divide by
 993                  * 2 the depth of the queue.
 994                  */
 995                 info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
 996         } else
 997                 info->tag_set.queue_depth = BLK_RING_SIZE(info);
 998         info->tag_set.numa_node = NUMA_NO_NODE;
 999         info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
1000         info->tag_set.cmd_size = sizeof(struct blkif_req);
1001         info->tag_set.driver_data = info;
1002
1003         if (blk_mq_alloc_tag_set(&info->tag_set))
1004                 return -EINVAL;
1005         rq = blk_mq_init_queue(&info->tag_set);
1006         if (IS_ERR(rq)) {
1007                 blk_mq_free_tag_set(&info->tag_set);
1008                 return PTR_ERR(rq);
1009         }
1010
1011         rq->queuedata = info;
1012         info->rq = gd->queue = rq;
1013         info->gd = gd;
1014         info->sector_size = sector_size;
1015         info->physical_sector_size = physical_sector_size;
1016         blkif_set_queue_limits(info);
1017
1018         return 0;
1019 }
1020
1021 static const char *flush_info(struct blkfront_info *info)
1022 {
1023         if (info->feature_flush && info->feature_fua)
1024                 return "barrier: enabled;";
1025         else if (info->feature_flush)
1026                 return "flush diskcache: enabled;";
1027         else
1028                 return "barrier or flush: disabled;";
1029 }
1030
1031 static void xlvbd_flush(struct blkfront_info *info)
1032 {
1033         blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
1034                               info->feature_fua ? true : false);
1035         pr_info("blkfront: %s: %s %s %s %s %s %s %s\n",
1036                 info->gd->disk_name, flush_info(info),
1037                 "persistent grants:", info->feature_persistent ?
1038                 "enabled;" : "disabled;", "indirect descriptors:",
1039                 info->max_indirect_segments ? "enabled;" : "disabled;",
1040                 "bounce buffer:", info->bounce ? "enabled" : "disabled;");
1041 }
1042
1043 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1044 {
1045         int major;
1046         major = BLKIF_MAJOR(vdevice);
1047         *minor = BLKIF_MINOR(vdevice);
1048         switch (major) {
1049                 case XEN_IDE0_MAJOR:
1050                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1051                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
1052                                 EMULATED_HD_DISK_MINOR_OFFSET;
1053                         break;
1054                 case XEN_IDE1_MAJOR:
1055                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1056                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1057                                 EMULATED_HD_DISK_MINOR_OFFSET;
1058                         break;
1059                 case XEN_SCSI_DISK0_MAJOR:
1060                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1061                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1062                         break;
1063                 case XEN_SCSI_DISK1_MAJOR:
1064                 case XEN_SCSI_DISK2_MAJOR:
1065                 case XEN_SCSI_DISK3_MAJOR:
1066                 case XEN_SCSI_DISK4_MAJOR:
1067                 case XEN_SCSI_DISK5_MAJOR:
1068                 case XEN_SCSI_DISK6_MAJOR:
1069                 case XEN_SCSI_DISK7_MAJOR:
1070                         *offset = (*minor / PARTS_PER_DISK) +
1071                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1072                                 EMULATED_SD_DISK_NAME_OFFSET;
1073                         *minor = *minor +
1074                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1075                                 EMULATED_SD_DISK_MINOR_OFFSET;
1076                         break;
1077                 case XEN_SCSI_DISK8_MAJOR:
1078                 case XEN_SCSI_DISK9_MAJOR:
1079                 case XEN_SCSI_DISK10_MAJOR:
1080                 case XEN_SCSI_DISK11_MAJOR:
1081                 case XEN_SCSI_DISK12_MAJOR:
1082                 case XEN_SCSI_DISK13_MAJOR:
1083                 case XEN_SCSI_DISK14_MAJOR:
1084                 case XEN_SCSI_DISK15_MAJOR:
1085                         *offset = (*minor / PARTS_PER_DISK) +
1086                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1087                                 EMULATED_SD_DISK_NAME_OFFSET;
1088                         *minor = *minor +
1089                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1090                                 EMULATED_SD_DISK_MINOR_OFFSET;
1091                         break;
1092                 case XENVBD_MAJOR:
1093                         *offset = *minor / PARTS_PER_DISK;
1094                         break;
1095                 default:
1096                         printk(KERN_WARNING "blkfront: your disk configuration is "
1097                                         "incorrect, please use an xvd device instead\n");
1098                         return -ENODEV;
1099         }
1100         return 0;
1101 }
1102
1103 static char *encode_disk_name(char *ptr, unsigned int n)
1104 {
1105         if (n >= 26)
1106                 ptr = encode_disk_name(ptr, n / 26 - 1);
1107         *ptr = 'a' + n % 26;
1108         return ptr + 1;
1109 }
1110
1111 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1112                                struct blkfront_info *info,
1113                                u16 vdisk_info, u16 sector_size,
1114                                unsigned int physical_sector_size)
1115 {
1116         struct gendisk *gd;
1117         int nr_minors = 1;
1118         int err;
1119         unsigned int offset;
1120         int minor;
1121         int nr_parts;
1122         char *ptr;
1123
1124         BUG_ON(info->gd != NULL);
1125         BUG_ON(info->rq != NULL);
1126
1127         if ((info->vdevice>>EXT_SHIFT) > 1) {
1128                 /* this is above the extended range; something is wrong */
1129                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1130                 return -ENODEV;
1131         }
1132
1133         if (!VDEV_IS_EXTENDED(info->vdevice)) {
1134                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1135                 if (err)
1136                         return err;
1137                 nr_parts = PARTS_PER_DISK;
1138         } else {
1139                 minor = BLKIF_MINOR_EXT(info->vdevice);
1140                 nr_parts = PARTS_PER_EXT_DISK;
1141                 offset = minor / nr_parts;
1142                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1143                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1144                                         "emulated IDE disks,\n\t choose an xvd device name"
1145                                         "from xvde on\n", info->vdevice);
1146         }
1147         if (minor >> MINORBITS) {
1148                 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1149                         info->vdevice, minor);
1150                 return -ENODEV;
1151         }
1152
1153         if ((minor % nr_parts) == 0)
1154                 nr_minors = nr_parts;
1155
1156         err = xlbd_reserve_minors(minor, nr_minors);
1157         if (err)
1158                 goto out;
1159         err = -ENODEV;
1160
1161         gd = alloc_disk(nr_minors);
1162         if (gd == NULL)
1163                 goto release;
1164
1165         strcpy(gd->disk_name, DEV_NAME);
1166         ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1167         BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1168         if (nr_minors > 1)
1169                 *ptr = 0;
1170         else
1171                 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1172                          "%d", minor & (nr_parts - 1));
1173
1174         gd->major = XENVBD_MAJOR;
1175         gd->first_minor = minor;
1176         gd->fops = &xlvbd_block_fops;
1177         gd->private_data = info;
1178         set_capacity(gd, capacity);
1179
1180         if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
1181                 del_gendisk(gd);
1182                 goto release;
1183         }
1184
1185         xlvbd_flush(info);
1186
1187         if (vdisk_info & VDISK_READONLY)
1188                 set_disk_ro(gd, 1);
1189
1190         if (vdisk_info & VDISK_REMOVABLE)
1191                 gd->flags |= GENHD_FL_REMOVABLE;
1192
1193         if (vdisk_info & VDISK_CDROM)
1194                 gd->flags |= GENHD_FL_CD;
1195
1196         return 0;
1197
1198  release:
1199         xlbd_release_minors(minor, nr_minors);
1200  out:
1201         return err;
1202 }
1203
1204 static void xlvbd_release_gendisk(struct blkfront_info *info)
1205 {
1206         unsigned int minor, nr_minors, i;
1207
1208         if (info->rq == NULL)
1209                 return;
1210
1211         /* No more blkif_request(). */
1212         blk_mq_stop_hw_queues(info->rq);
1213
1214         for (i = 0; i < info->nr_rings; i++) {
1215                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1216
1217                 /* No more gnttab callback work. */
1218                 gnttab_cancel_free_callback(&rinfo->callback);
1219
1220                 /* Flush gnttab callback work. Must be done with no locks held. */
1221                 flush_work(&rinfo->work);
1222         }
1223
1224         del_gendisk(info->gd);
1225
1226         minor = info->gd->first_minor;
1227         nr_minors = info->gd->minors;
1228         xlbd_release_minors(minor, nr_minors);
1229
1230         blk_cleanup_queue(info->rq);
1231         blk_mq_free_tag_set(&info->tag_set);
1232         info->rq = NULL;
1233
1234         put_disk(info->gd);
1235         info->gd = NULL;
1236 }
1237
1238 /* Already hold rinfo->ring_lock. */
1239 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1240 {
1241         if (!RING_FULL(&rinfo->ring))
1242                 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1243 }
1244
1245 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1246 {
1247         unsigned long flags;
1248
1249         spin_lock_irqsave(&rinfo->ring_lock, flags);
1250         kick_pending_request_queues_locked(rinfo);
1251         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1252 }
1253
1254 static void blkif_restart_queue(struct work_struct *work)
1255 {
1256         struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1257
1258         if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1259                 kick_pending_request_queues(rinfo);
1260 }
1261
1262 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1263 {
1264         struct grant *persistent_gnt, *n;
1265         struct blkfront_info *info = rinfo->dev_info;
1266         int i, j, segs;
1267
1268         /*
1269          * Remove indirect pages, this only happens when using indirect
1270          * descriptors but not persistent grants
1271          */
1272         if (!list_empty(&rinfo->indirect_pages)) {
1273                 struct page *indirect_page, *n;
1274
1275                 BUG_ON(info->bounce);
1276                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1277                         list_del(&indirect_page->lru);
1278                         __free_page(indirect_page);
1279                 }
1280         }
1281
1282         /* Remove all persistent grants. */
1283         if (!list_empty(&rinfo->grants)) {
1284                 list_for_each_entry_safe(persistent_gnt, n,
1285                                          &rinfo->grants, node) {
1286                         list_del(&persistent_gnt->node);
1287                         if (persistent_gnt->gref != GRANT_INVALID_REF) {
1288                                 gnttab_end_foreign_access(persistent_gnt->gref,
1289                                                           0, 0UL);
1290                                 rinfo->persistent_gnts_c--;
1291                         }
1292                         if (info->bounce)
1293                                 __free_page(persistent_gnt->page);
1294                         kfree(persistent_gnt);
1295                 }
1296         }
1297         BUG_ON(rinfo->persistent_gnts_c != 0);
1298
1299         for (i = 0; i < BLK_RING_SIZE(info); i++) {
1300                 /*
1301                  * Clear persistent grants present in requests already
1302                  * on the shared ring
1303                  */
1304                 if (!rinfo->shadow[i].request)
1305                         goto free_shadow;
1306
1307                 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1308                        rinfo->shadow[i].req.u.indirect.nr_segments :
1309                        rinfo->shadow[i].req.u.rw.nr_segments;
1310                 for (j = 0; j < segs; j++) {
1311                         persistent_gnt = rinfo->shadow[i].grants_used[j];
1312                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1313                         if (info->bounce)
1314                                 __free_page(persistent_gnt->page);
1315                         kfree(persistent_gnt);
1316                 }
1317
1318                 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1319                         /*
1320                          * If this is not an indirect operation don't try to
1321                          * free indirect segments
1322                          */
1323                         goto free_shadow;
1324
1325                 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1326                         persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1327                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1328                         __free_page(persistent_gnt->page);
1329                         kfree(persistent_gnt);
1330                 }
1331
1332 free_shadow:
1333                 kvfree(rinfo->shadow[i].grants_used);
1334                 rinfo->shadow[i].grants_used = NULL;
1335                 kvfree(rinfo->shadow[i].indirect_grants);
1336                 rinfo->shadow[i].indirect_grants = NULL;
1337                 kvfree(rinfo->shadow[i].sg);
1338                 rinfo->shadow[i].sg = NULL;
1339         }
1340
1341         /* No more gnttab callback work. */
1342         gnttab_cancel_free_callback(&rinfo->callback);
1343
1344         /* Flush gnttab callback work. Must be done with no locks held. */
1345         flush_work(&rinfo->work);
1346
1347         /* Free resources associated with old device channel. */
1348         for (i = 0; i < info->nr_ring_pages; i++) {
1349                 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1350                         gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1351                         rinfo->ring_ref[i] = GRANT_INVALID_REF;
1352                 }
1353         }
1354         free_pages_exact(rinfo->ring.sring,
1355                          info->nr_ring_pages * XEN_PAGE_SIZE);
1356         rinfo->ring.sring = NULL;
1357
1358         if (rinfo->irq)
1359                 unbind_from_irqhandler(rinfo->irq, rinfo);
1360         rinfo->evtchn = rinfo->irq = 0;
1361 }
1362
1363 static void blkif_free(struct blkfront_info *info, int suspend)
1364 {
1365         unsigned int i;
1366
1367         /* Prevent new requests being issued until we fix things up. */
1368         info->connected = suspend ?
1369                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1370         /* No more blkif_request(). */
1371         if (info->rq)
1372                 blk_mq_stop_hw_queues(info->rq);
1373
1374         for (i = 0; i < info->nr_rings; i++)
1375                 blkif_free_ring(&info->rinfo[i]);
1376
1377         kvfree(info->rinfo);
1378         info->rinfo = NULL;
1379         info->nr_rings = 0;
1380 }
1381
1382 struct copy_from_grant {
1383         const struct blk_shadow *s;
1384         unsigned int grant_idx;
1385         unsigned int bvec_offset;
1386         char *bvec_data;
1387 };
1388
1389 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1390                                   unsigned int len, void *data)
1391 {
1392         struct copy_from_grant *info = data;
1393         char *shared_data;
1394         /* Convenient aliases */
1395         const struct blk_shadow *s = info->s;
1396
1397         shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1398
1399         memcpy(info->bvec_data + info->bvec_offset,
1400                shared_data + offset, len);
1401
1402         info->bvec_offset += len;
1403         info->grant_idx++;
1404
1405         kunmap_atomic(shared_data);
1406 }
1407
1408 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1409 {
1410         switch (rsp)
1411         {
1412         case BLKIF_RSP_OKAY:
1413                 return REQ_DONE;
1414         case BLKIF_RSP_EOPNOTSUPP:
1415                 return REQ_EOPNOTSUPP;
1416         case BLKIF_RSP_ERROR:
1417                 /* Fallthrough. */
1418         default:
1419                 return REQ_ERROR;
1420         }
1421 }
1422
1423 /*
1424  * Get the final status of the block request based on two ring response
1425  */
1426 static int blkif_get_final_status(enum blk_req_status s1,
1427                                   enum blk_req_status s2)
1428 {
1429         BUG_ON(s1 < REQ_DONE);
1430         BUG_ON(s2 < REQ_DONE);
1431
1432         if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1433                 return BLKIF_RSP_ERROR;
1434         else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1435                 return BLKIF_RSP_EOPNOTSUPP;
1436         return BLKIF_RSP_OKAY;
1437 }
1438
1439 /*
1440  * Return values:
1441  *  1 response processed.
1442  *  0 missing further responses.
1443  * -1 error while processing.
1444  */
1445 static int blkif_completion(unsigned long *id,
1446                             struct blkfront_ring_info *rinfo,
1447                             struct blkif_response *bret)
1448 {
1449         int i = 0;
1450         struct scatterlist *sg;
1451         int num_sg, num_grant;
1452         struct blkfront_info *info = rinfo->dev_info;
1453         struct blk_shadow *s = &rinfo->shadow[*id];
1454         struct copy_from_grant data = {
1455                 .grant_idx = 0,
1456         };
1457
1458         num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1459                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1460
1461         /* The I/O request may be split in two. */
1462         if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1463                 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1464
1465                 /* Keep the status of the current response in shadow. */
1466                 s->status = blkif_rsp_to_req_status(bret->status);
1467
1468                 /* Wait the second response if not yet here. */
1469                 if (s2->status < REQ_DONE)
1470                         return 0;
1471
1472                 bret->status = blkif_get_final_status(s->status,
1473                                                       s2->status);
1474
1475                 /*
1476                  * All the grants is stored in the first shadow in order
1477                  * to make the completion code simpler.
1478                  */
1479                 num_grant += s2->req.u.rw.nr_segments;
1480
1481                 /*
1482                  * The two responses may not come in order. Only the
1483                  * first request will store the scatter-gather list.
1484                  */
1485                 if (s2->num_sg != 0) {
1486                         /* Update "id" with the ID of the first response. */
1487                         *id = s->associated_id;
1488                         s = s2;
1489                 }
1490
1491                 /*
1492                  * We don't need anymore the second request, so recycling
1493                  * it now.
1494                  */
1495                 if (add_id_to_freelist(rinfo, s->associated_id))
1496                         WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1497                              info->gd->disk_name, s->associated_id);
1498         }
1499
1500         data.s = s;
1501         num_sg = s->num_sg;
1502
1503         if (bret->operation == BLKIF_OP_READ && info->bounce) {
1504                 for_each_sg(s->sg, sg, num_sg, i) {
1505                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1506
1507                         data.bvec_offset = sg->offset;
1508                         data.bvec_data = kmap_atomic(sg_page(sg));
1509
1510                         gnttab_foreach_grant_in_range(sg_page(sg),
1511                                                       sg->offset,
1512                                                       sg->length,
1513                                                       blkif_copy_from_grant,
1514                                                       &data);
1515
1516                         kunmap_atomic(data.bvec_data);
1517                 }
1518         }
1519         /* Add the persistent grant into the list of free grants */
1520         for (i = 0; i < num_grant; i++) {
1521                 if (!gnttab_try_end_foreign_access(s->grants_used[i]->gref)) {
1522                         /*
1523                          * If the grant is still mapped by the backend (the
1524                          * backend has chosen to make this grant persistent)
1525                          * we add it at the head of the list, so it will be
1526                          * reused first.
1527                          */
1528                         if (!info->feature_persistent) {
1529                                 pr_alert("backed has not unmapped grant: %u\n",
1530                                          s->grants_used[i]->gref);
1531                                 return -1;
1532                         }
1533                         list_add(&s->grants_used[i]->node, &rinfo->grants);
1534                         rinfo->persistent_gnts_c++;
1535                 } else {
1536                         /*
1537                          * If the grant is not mapped by the backend we add it
1538                          * to the tail of the list, so it will not be picked
1539                          * again unless we run out of persistent grants.
1540                          */
1541                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1542                         list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1543                 }
1544         }
1545         if (s->req.operation == BLKIF_OP_INDIRECT) {
1546                 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1547                         if (!gnttab_try_end_foreign_access(s->indirect_grants[i]->gref)) {
1548                                 if (!info->feature_persistent) {
1549                                         pr_alert("backed has not unmapped grant: %u\n",
1550                                                  s->indirect_grants[i]->gref);
1551                                         return -1;
1552                                 }
1553                                 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1554                                 rinfo->persistent_gnts_c++;
1555                         } else {
1556                                 struct page *indirect_page;
1557
1558                                 /*
1559                                  * Add the used indirect page back to the list of
1560                                  * available pages for indirect grefs.
1561                                  */
1562                                 if (!info->bounce) {
1563                                         indirect_page = s->indirect_grants[i]->page;
1564                                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
1565                                 }
1566                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1567                                 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1568                         }
1569                 }
1570         }
1571
1572         return 1;
1573 }
1574
1575 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1576 {
1577         struct request *req;
1578         struct blkif_response bret;
1579         RING_IDX i, rp;
1580         unsigned long flags;
1581         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1582         struct blkfront_info *info = rinfo->dev_info;
1583         unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;
1584
1585         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1586                 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
1587                 return IRQ_HANDLED;
1588         }
1589
1590         spin_lock_irqsave(&rinfo->ring_lock, flags);
1591  again:
1592         rp = READ_ONCE(rinfo->ring.sring->rsp_prod);
1593         virt_rmb(); /* Ensure we see queued responses up to 'rp'. */
1594         if (RING_RESPONSE_PROD_OVERFLOW(&rinfo->ring, rp)) {
1595                 pr_alert("%s: illegal number of responses %u\n",
1596                          info->gd->disk_name, rp - rinfo->ring.rsp_cons);
1597                 goto err;
1598         }
1599
1600         for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1601                 unsigned long id;
1602                 unsigned int op;
1603
1604                 eoiflag = 0;
1605
1606                 RING_COPY_RESPONSE(&rinfo->ring, i, &bret);
1607                 id = bret.id;
1608
1609                 /*
1610                  * The backend has messed up and given us an id that we would
1611                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1612                  * look in get_id_from_freelist.
1613                  */
1614                 if (id >= BLK_RING_SIZE(info)) {
1615                         pr_alert("%s: response has incorrect id (%ld)\n",
1616                                  info->gd->disk_name, id);
1617                         goto err;
1618                 }
1619                 if (rinfo->shadow[id].status != REQ_WAITING) {
1620                         pr_alert("%s: response references no pending request\n",
1621                                  info->gd->disk_name);
1622                         goto err;
1623                 }
1624
1625                 rinfo->shadow[id].status = REQ_PROCESSING;
1626                 req  = rinfo->shadow[id].request;
1627
1628                 op = rinfo->shadow[id].req.operation;
1629                 if (op == BLKIF_OP_INDIRECT)
1630                         op = rinfo->shadow[id].req.u.indirect.indirect_op;
1631                 if (bret.operation != op) {
1632                         pr_alert("%s: response has wrong operation (%u instead of %u)\n",
1633                                  info->gd->disk_name, bret.operation, op);
1634                         goto err;
1635                 }
1636
1637                 if (bret.operation != BLKIF_OP_DISCARD) {
1638                         int ret;
1639
1640                         /*
1641                          * We may need to wait for an extra response if the
1642                          * I/O request is split in 2
1643                          */
1644                         ret = blkif_completion(&id, rinfo, &bret);
1645                         if (!ret)
1646                                 continue;
1647                         if (unlikely(ret < 0))
1648                                 goto err;
1649                 }
1650
1651                 if (add_id_to_freelist(rinfo, id)) {
1652                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1653                              info->gd->disk_name, op_name(bret.operation), id);
1654                         continue;
1655                 }
1656
1657                 if (bret.status == BLKIF_RSP_OKAY)
1658                         blkif_req(req)->error = BLK_STS_OK;
1659                 else
1660                         blkif_req(req)->error = BLK_STS_IOERR;
1661
1662                 switch (bret.operation) {
1663                 case BLKIF_OP_DISCARD:
1664                         if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1665                                 struct request_queue *rq = info->rq;
1666
1667                                 pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1668                                            info->gd->disk_name, op_name(bret.operation));
1669                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1670                                 info->feature_discard = 0;
1671                                 info->feature_secdiscard = 0;
1672                                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1673                                 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1674                         }
1675                         break;
1676                 case BLKIF_OP_FLUSH_DISKCACHE:
1677                 case BLKIF_OP_WRITE_BARRIER:
1678                         if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1679                                 pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1680                                        info->gd->disk_name, op_name(bret.operation));
1681                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1682                         }
1683                         if (unlikely(bret.status == BLKIF_RSP_ERROR &&
1684                                      rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1685                                 pr_warn_ratelimited("blkfront: %s: empty %s op failed\n",
1686                                        info->gd->disk_name, op_name(bret.operation));
1687                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1688                         }
1689                         if (unlikely(blkif_req(req)->error)) {
1690                                 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1691                                         blkif_req(req)->error = BLK_STS_OK;
1692                                 info->feature_fua = 0;
1693                                 info->feature_flush = 0;
1694                                 xlvbd_flush(info);
1695                         }
1696                         /* fall through */
1697                 case BLKIF_OP_READ:
1698                 case BLKIF_OP_WRITE:
1699                         if (unlikely(bret.status != BLKIF_RSP_OKAY))
1700                                 dev_dbg_ratelimited(&info->xbdev->dev,
1701                                         "Bad return from blkdev data request: %#x\n",
1702                                         bret.status);
1703
1704                         break;
1705                 default:
1706                         BUG();
1707                 }
1708
1709                 blk_mq_complete_request(req);
1710         }
1711
1712         rinfo->ring.rsp_cons = i;
1713
1714         if (i != rinfo->ring.req_prod_pvt) {
1715                 int more_to_do;
1716                 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1717                 if (more_to_do)
1718                         goto again;
1719         } else
1720                 rinfo->ring.sring->rsp_event = i + 1;
1721
1722         kick_pending_request_queues_locked(rinfo);
1723
1724         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1725
1726         xen_irq_lateeoi(irq, eoiflag);
1727
1728         return IRQ_HANDLED;
1729
1730  err:
1731         info->connected = BLKIF_STATE_ERROR;
1732
1733         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1734
1735         /* No EOI in order to avoid further interrupts. */
1736
1737         pr_alert("%s disabled for further use\n", info->gd->disk_name);
1738         return IRQ_HANDLED;
1739 }
1740
1741
1742 static int setup_blkring(struct xenbus_device *dev,
1743                          struct blkfront_ring_info *rinfo)
1744 {
1745         struct blkif_sring *sring;
1746         int err, i;
1747         struct blkfront_info *info = rinfo->dev_info;
1748         unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1749         grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1750
1751         for (i = 0; i < info->nr_ring_pages; i++)
1752                 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1753
1754         sring = alloc_pages_exact(ring_size, GFP_NOIO | __GFP_ZERO);
1755         if (!sring) {
1756                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1757                 return -ENOMEM;
1758         }
1759         SHARED_RING_INIT(sring);
1760         FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1761
1762         err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1763         if (err < 0) {
1764                 free_pages_exact(sring, ring_size);
1765                 rinfo->ring.sring = NULL;
1766                 goto fail;
1767         }
1768         for (i = 0; i < info->nr_ring_pages; i++)
1769                 rinfo->ring_ref[i] = gref[i];
1770
1771         err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1772         if (err)
1773                 goto fail;
1774
1775         err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt,
1776                                                 0, "blkif", rinfo);
1777         if (err <= 0) {
1778                 xenbus_dev_fatal(dev, err,
1779                                  "bind_evtchn_to_irqhandler failed");
1780                 goto fail;
1781         }
1782         rinfo->irq = err;
1783
1784         return 0;
1785 fail:
1786         blkif_free(info, 0);
1787         return err;
1788 }
1789
1790 /*
1791  * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1792  * ring buffer may have multi pages depending on ->nr_ring_pages.
1793  */
1794 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1795                                 struct blkfront_ring_info *rinfo, const char *dir)
1796 {
1797         int err;
1798         unsigned int i;
1799         const char *message = NULL;
1800         struct blkfront_info *info = rinfo->dev_info;
1801
1802         if (info->nr_ring_pages == 1) {
1803                 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1804                 if (err) {
1805                         message = "writing ring-ref";
1806                         goto abort_transaction;
1807                 }
1808         } else {
1809                 for (i = 0; i < info->nr_ring_pages; i++) {
1810                         char ring_ref_name[RINGREF_NAME_LEN];
1811
1812                         snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1813                         err = xenbus_printf(xbt, dir, ring_ref_name,
1814                                             "%u", rinfo->ring_ref[i]);
1815                         if (err) {
1816                                 message = "writing ring-ref";
1817                                 goto abort_transaction;
1818                         }
1819                 }
1820         }
1821
1822         err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1823         if (err) {
1824                 message = "writing event-channel";
1825                 goto abort_transaction;
1826         }
1827
1828         return 0;
1829
1830 abort_transaction:
1831         xenbus_transaction_end(xbt, 1);
1832         if (message)
1833                 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1834
1835         return err;
1836 }
1837
1838 static void free_info(struct blkfront_info *info)
1839 {
1840         list_del(&info->info_list);
1841         kfree(info);
1842 }
1843
1844 /* Common code used when first setting up, and when resuming. */
1845 static int talk_to_blkback(struct xenbus_device *dev,
1846                            struct blkfront_info *info)
1847 {
1848         const char *message = NULL;
1849         struct xenbus_transaction xbt;
1850         int err;
1851         unsigned int i, max_page_order;
1852         unsigned int ring_page_order;
1853
1854         if (!info)
1855                 return -ENODEV;
1856
1857         /* Check if backend is trusted. */
1858         info->bounce = !xen_blkif_trusted ||
1859                        !xenbus_read_unsigned(dev->nodename, "trusted", 1);
1860
1861         max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1862                                               "max-ring-page-order", 0);
1863         ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1864         info->nr_ring_pages = 1 << ring_page_order;
1865
1866         err = negotiate_mq(info);
1867         if (err)
1868                 goto destroy_blkring;
1869
1870         for (i = 0; i < info->nr_rings; i++) {
1871                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1872
1873                 /* Create shared ring, alloc event channel. */
1874                 err = setup_blkring(dev, rinfo);
1875                 if (err)
1876                         goto destroy_blkring;
1877         }
1878
1879 again:
1880         err = xenbus_transaction_start(&xbt);
1881         if (err) {
1882                 xenbus_dev_fatal(dev, err, "starting transaction");
1883                 goto destroy_blkring;
1884         }
1885
1886         if (info->nr_ring_pages > 1) {
1887                 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1888                                     ring_page_order);
1889                 if (err) {
1890                         message = "writing ring-page-order";
1891                         goto abort_transaction;
1892                 }
1893         }
1894
1895         /* We already got the number of queues/rings in _probe */
1896         if (info->nr_rings == 1) {
1897                 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1898                 if (err)
1899                         goto destroy_blkring;
1900         } else {
1901                 char *path;
1902                 size_t pathsize;
1903
1904                 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1905                                     info->nr_rings);
1906                 if (err) {
1907                         message = "writing multi-queue-num-queues";
1908                         goto abort_transaction;
1909                 }
1910
1911                 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1912                 path = kmalloc(pathsize, GFP_KERNEL);
1913                 if (!path) {
1914                         err = -ENOMEM;
1915                         message = "ENOMEM while writing ring references";
1916                         goto abort_transaction;
1917                 }
1918
1919                 for (i = 0; i < info->nr_rings; i++) {
1920                         memset(path, 0, pathsize);
1921                         snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1922                         err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1923                         if (err) {
1924                                 kfree(path);
1925                                 goto destroy_blkring;
1926                         }
1927                 }
1928                 kfree(path);
1929         }
1930         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1931                             XEN_IO_PROTO_ABI_NATIVE);
1932         if (err) {
1933                 message = "writing protocol";
1934                 goto abort_transaction;
1935         }
1936         err = xenbus_printf(xbt, dev->nodename,
1937                             "feature-persistent", "%u", 1);
1938         if (err)
1939                 dev_warn(&dev->dev,
1940                          "writing persistent grants feature to xenbus");
1941
1942         err = xenbus_transaction_end(xbt, 0);
1943         if (err) {
1944                 if (err == -EAGAIN)
1945                         goto again;
1946                 xenbus_dev_fatal(dev, err, "completing transaction");
1947                 goto destroy_blkring;
1948         }
1949
1950         for (i = 0; i < info->nr_rings; i++) {
1951                 unsigned int j;
1952                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1953
1954                 for (j = 0; j < BLK_RING_SIZE(info); j++)
1955                         rinfo->shadow[j].req.u.rw.id = j + 1;
1956                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1957         }
1958         xenbus_switch_state(dev, XenbusStateInitialised);
1959
1960         return 0;
1961
1962  abort_transaction:
1963         xenbus_transaction_end(xbt, 1);
1964         if (message)
1965                 xenbus_dev_fatal(dev, err, "%s", message);
1966  destroy_blkring:
1967         blkif_free(info, 0);
1968
1969         mutex_lock(&blkfront_mutex);
1970         free_info(info);
1971         mutex_unlock(&blkfront_mutex);
1972
1973         dev_set_drvdata(&dev->dev, NULL);
1974
1975         return err;
1976 }
1977
1978 static int negotiate_mq(struct blkfront_info *info)
1979 {
1980         unsigned int backend_max_queues;
1981         unsigned int i;
1982
1983         BUG_ON(info->nr_rings);
1984
1985         /* Check if backend supports multiple queues. */
1986         backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1987                                                   "multi-queue-max-queues", 1);
1988         info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1989         /* We need at least one ring. */
1990         if (!info->nr_rings)
1991                 info->nr_rings = 1;
1992
1993         info->rinfo = kvcalloc(info->nr_rings,
1994                                sizeof(struct blkfront_ring_info),
1995                                GFP_KERNEL);
1996         if (!info->rinfo) {
1997                 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1998                 info->nr_rings = 0;
1999                 return -ENOMEM;
2000         }
2001
2002         for (i = 0; i < info->nr_rings; i++) {
2003                 struct blkfront_ring_info *rinfo;
2004
2005                 rinfo = &info->rinfo[i];
2006                 INIT_LIST_HEAD(&rinfo->indirect_pages);
2007                 INIT_LIST_HEAD(&rinfo->grants);
2008                 rinfo->dev_info = info;
2009                 INIT_WORK(&rinfo->work, blkif_restart_queue);
2010                 spin_lock_init(&rinfo->ring_lock);
2011         }
2012         return 0;
2013 }
2014 /**
2015  * Entry point to this code when a new device is created.  Allocate the basic
2016  * structures and the ring buffer for communication with the backend, and
2017  * inform the backend of the appropriate details for those.  Switch to
2018  * Initialised state.
2019  */
2020 static int blkfront_probe(struct xenbus_device *dev,
2021                           const struct xenbus_device_id *id)
2022 {
2023         int err, vdevice;
2024         struct blkfront_info *info;
2025
2026         /* FIXME: Use dynamic device id if this is not set. */
2027         err = xenbus_scanf(XBT_NIL, dev->nodename,
2028                            "virtual-device", "%i", &vdevice);
2029         if (err != 1) {
2030                 /* go looking in the extended area instead */
2031                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
2032                                    "%i", &vdevice);
2033                 if (err != 1) {
2034                         xenbus_dev_fatal(dev, err, "reading virtual-device");
2035                         return err;
2036                 }
2037         }
2038
2039         if (xen_hvm_domain()) {
2040                 char *type;
2041                 int len;
2042                 /* no unplug has been done: do not hook devices != xen vbds */
2043                 if (xen_has_pv_and_legacy_disk_devices()) {
2044                         int major;
2045
2046                         if (!VDEV_IS_EXTENDED(vdevice))
2047                                 major = BLKIF_MAJOR(vdevice);
2048                         else
2049                                 major = XENVBD_MAJOR;
2050
2051                         if (major != XENVBD_MAJOR) {
2052                                 printk(KERN_INFO
2053                                                 "%s: HVM does not support vbd %d as xen block device\n",
2054                                                 __func__, vdevice);
2055                                 return -ENODEV;
2056                         }
2057                 }
2058                 /* do not create a PV cdrom device if we are an HVM guest */
2059                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
2060                 if (IS_ERR(type))
2061                         return -ENODEV;
2062                 if (strncmp(type, "cdrom", 5) == 0) {
2063                         kfree(type);
2064                         return -ENODEV;
2065                 }
2066                 kfree(type);
2067         }
2068         info = kzalloc(sizeof(*info), GFP_KERNEL);
2069         if (!info) {
2070                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
2071                 return -ENOMEM;
2072         }
2073
2074         info->xbdev = dev;
2075
2076         mutex_init(&info->mutex);
2077         info->vdevice = vdevice;
2078         info->connected = BLKIF_STATE_DISCONNECTED;
2079
2080         /* Front end dir is a number, which is used as the id. */
2081         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
2082         dev_set_drvdata(&dev->dev, info);
2083
2084         mutex_lock(&blkfront_mutex);
2085         list_add(&info->info_list, &info_list);
2086         mutex_unlock(&blkfront_mutex);
2087
2088         return 0;
2089 }
2090
2091 static int blkif_recover(struct blkfront_info *info)
2092 {
2093         unsigned int r_index;
2094         struct request *req, *n;
2095         int rc;
2096         struct bio *bio;
2097         unsigned int segs;
2098
2099         blkfront_gather_backend_features(info);
2100         /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2101         blkif_set_queue_limits(info);
2102         segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2103         blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2104
2105         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2106                 struct blkfront_ring_info *rinfo = &info->rinfo[r_index];
2107
2108                 rc = blkfront_setup_indirect(rinfo);
2109                 if (rc)
2110                         return rc;
2111         }
2112         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2113
2114         /* Now safe for us to use the shared ring */
2115         info->connected = BLKIF_STATE_CONNECTED;
2116
2117         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2118                 struct blkfront_ring_info *rinfo;
2119
2120                 rinfo = &info->rinfo[r_index];
2121                 /* Kick any other new requests queued since we resumed */
2122                 kick_pending_request_queues(rinfo);
2123         }
2124
2125         list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2126                 /* Requeue pending requests (flush or discard) */
2127                 list_del_init(&req->queuelist);
2128                 BUG_ON(req->nr_phys_segments > segs);
2129                 blk_mq_requeue_request(req, false);
2130         }
2131         blk_mq_start_stopped_hw_queues(info->rq, true);
2132         blk_mq_kick_requeue_list(info->rq);
2133
2134         while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2135                 /* Traverse the list of pending bios and re-queue them */
2136                 submit_bio(bio);
2137         }
2138
2139         return 0;
2140 }
2141
2142 /**
2143  * We are reconnecting to the backend, due to a suspend/resume, or a backend
2144  * driver restart.  We tear down our blkif structure and recreate it, but
2145  * leave the device-layer structures intact so that this is transparent to the
2146  * rest of the kernel.
2147  */
2148 static int blkfront_resume(struct xenbus_device *dev)
2149 {
2150         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2151         int err = 0;
2152         unsigned int i, j;
2153
2154         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2155
2156         bio_list_init(&info->bio_list);
2157         INIT_LIST_HEAD(&info->requests);
2158         for (i = 0; i < info->nr_rings; i++) {
2159                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2160                 struct bio_list merge_bio;
2161                 struct blk_shadow *shadow = rinfo->shadow;
2162
2163                 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2164                         /* Not in use? */
2165                         if (!shadow[j].request)
2166                                 continue;
2167
2168                         /*
2169                          * Get the bios in the request so we can re-queue them.
2170                          */
2171                         if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2172                             req_op(shadow[j].request) == REQ_OP_DISCARD ||
2173                             req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2174                             shadow[j].request->cmd_flags & REQ_FUA) {
2175                                 /*
2176                                  * Flush operations don't contain bios, so
2177                                  * we need to requeue the whole request
2178                                  *
2179                                  * XXX: but this doesn't make any sense for a
2180                                  * write with the FUA flag set..
2181                                  */
2182                                 list_add(&shadow[j].request->queuelist, &info->requests);
2183                                 continue;
2184                         }
2185                         merge_bio.head = shadow[j].request->bio;
2186                         merge_bio.tail = shadow[j].request->biotail;
2187                         bio_list_merge(&info->bio_list, &merge_bio);
2188                         shadow[j].request->bio = NULL;
2189                         blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2190                 }
2191         }
2192
2193         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2194
2195         err = talk_to_blkback(dev, info);
2196         if (!err)
2197                 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2198
2199         /*
2200          * We have to wait for the backend to switch to
2201          * connected state, since we want to read which
2202          * features it supports.
2203          */
2204
2205         return err;
2206 }
2207
2208 static void blkfront_closing(struct blkfront_info *info)
2209 {
2210         struct xenbus_device *xbdev = info->xbdev;
2211         struct block_device *bdev = NULL;
2212
2213         mutex_lock(&info->mutex);
2214
2215         if (xbdev->state == XenbusStateClosing) {
2216                 mutex_unlock(&info->mutex);
2217                 return;
2218         }
2219
2220         if (info->gd)
2221                 bdev = bdget_disk(info->gd, 0);
2222
2223         mutex_unlock(&info->mutex);
2224
2225         if (!bdev) {
2226                 xenbus_frontend_closed(xbdev);
2227                 return;
2228         }
2229
2230         mutex_lock(&bdev->bd_mutex);
2231
2232         if (bdev->bd_openers) {
2233                 xenbus_dev_error(xbdev, -EBUSY,
2234                                  "Device in use; refusing to close");
2235                 xenbus_switch_state(xbdev, XenbusStateClosing);
2236         } else {
2237                 xlvbd_release_gendisk(info);
2238                 xenbus_frontend_closed(xbdev);
2239         }
2240
2241         mutex_unlock(&bdev->bd_mutex);
2242         bdput(bdev);
2243 }
2244
2245 static void blkfront_setup_discard(struct blkfront_info *info)
2246 {
2247         info->feature_discard = 1;
2248         info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
2249                                                          "discard-granularity",
2250                                                          0);
2251         info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
2252                                                        "discard-alignment", 0);
2253         info->feature_secdiscard =
2254                 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2255                                        0);
2256 }
2257
2258 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2259 {
2260         unsigned int psegs, grants, memflags;
2261         int err, i;
2262         struct blkfront_info *info = rinfo->dev_info;
2263
2264         memflags = memalloc_noio_save();
2265
2266         if (info->max_indirect_segments == 0) {
2267                 if (!HAS_EXTRA_REQ)
2268                         grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2269                 else {
2270                         /*
2271                          * When an extra req is required, the maximum
2272                          * grants supported is related to the size of the
2273                          * Linux block segment.
2274                          */
2275                         grants = GRANTS_PER_PSEG;
2276                 }
2277         }
2278         else
2279                 grants = info->max_indirect_segments;
2280         psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2281
2282         err = fill_grant_buffer(rinfo,
2283                                 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2284         if (err)
2285                 goto out_of_memory;
2286
2287         if (!info->bounce && info->max_indirect_segments) {
2288                 /*
2289                  * We are using indirect descriptors but don't have a bounce
2290                  * buffer, we need to allocate a set of pages that can be
2291                  * used for mapping indirect grefs
2292                  */
2293                 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2294
2295                 BUG_ON(!list_empty(&rinfo->indirect_pages));
2296                 for (i = 0; i < num; i++) {
2297                         struct page *indirect_page = alloc_page(GFP_KERNEL |
2298                                                                 __GFP_ZERO);
2299                         if (!indirect_page)
2300                                 goto out_of_memory;
2301                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
2302                 }
2303         }
2304
2305         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2306                 rinfo->shadow[i].grants_used =
2307                         kvcalloc(grants,
2308                                  sizeof(rinfo->shadow[i].grants_used[0]),
2309                                  GFP_KERNEL);
2310                 rinfo->shadow[i].sg = kvcalloc(psegs,
2311                                                sizeof(rinfo->shadow[i].sg[0]),
2312                                                GFP_KERNEL);
2313                 if (info->max_indirect_segments)
2314                         rinfo->shadow[i].indirect_grants =
2315                                 kvcalloc(INDIRECT_GREFS(grants),
2316                                          sizeof(rinfo->shadow[i].indirect_grants[0]),
2317                                          GFP_KERNEL);
2318                 if ((rinfo->shadow[i].grants_used == NULL) ||
2319                         (rinfo->shadow[i].sg == NULL) ||
2320                      (info->max_indirect_segments &&
2321                      (rinfo->shadow[i].indirect_grants == NULL)))
2322                         goto out_of_memory;
2323                 sg_init_table(rinfo->shadow[i].sg, psegs);
2324         }
2325
2326         memalloc_noio_restore(memflags);
2327
2328         return 0;
2329
2330 out_of_memory:
2331         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2332                 kvfree(rinfo->shadow[i].grants_used);
2333                 rinfo->shadow[i].grants_used = NULL;
2334                 kvfree(rinfo->shadow[i].sg);
2335                 rinfo->shadow[i].sg = NULL;
2336                 kvfree(rinfo->shadow[i].indirect_grants);
2337                 rinfo->shadow[i].indirect_grants = NULL;
2338         }
2339         if (!list_empty(&rinfo->indirect_pages)) {
2340                 struct page *indirect_page, *n;
2341                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2342                         list_del(&indirect_page->lru);
2343                         __free_page(indirect_page);
2344                 }
2345         }
2346
2347         memalloc_noio_restore(memflags);
2348
2349         return -ENOMEM;
2350 }
2351
2352 /*
2353  * Gather all backend feature-*
2354  */
2355 static void blkfront_gather_backend_features(struct blkfront_info *info)
2356 {
2357         unsigned int indirect_segments;
2358
2359         info->feature_flush = 0;
2360         info->feature_fua = 0;
2361
2362         /*
2363          * If there's no "feature-barrier" defined, then it means
2364          * we're dealing with a very old backend which writes
2365          * synchronously; nothing to do.
2366          *
2367          * If there are barriers, then we use flush.
2368          */
2369         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2370                 info->feature_flush = 1;
2371                 info->feature_fua = 1;
2372         }
2373
2374         /*
2375          * And if there is "feature-flush-cache" use that above
2376          * barriers.
2377          */
2378         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2379                                  0)) {
2380                 info->feature_flush = 1;
2381                 info->feature_fua = 0;
2382         }
2383
2384         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2385                 blkfront_setup_discard(info);
2386
2387         info->feature_persistent =
2388                 !!xenbus_read_unsigned(info->xbdev->otherend,
2389                                        "feature-persistent", 0);
2390         if (info->feature_persistent)
2391                 info->bounce = true;
2392
2393         indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2394                                         "feature-max-indirect-segments", 0);
2395         if (indirect_segments > xen_blkif_max_segments)
2396                 indirect_segments = xen_blkif_max_segments;
2397         if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2398                 indirect_segments = 0;
2399         info->max_indirect_segments = indirect_segments;
2400
2401         if (info->feature_persistent) {
2402                 mutex_lock(&blkfront_mutex);
2403                 schedule_delayed_work(&blkfront_work, HZ * 10);
2404                 mutex_unlock(&blkfront_mutex);
2405         }
2406 }
2407
2408 /*
2409  * Invoked when the backend is finally 'ready' (and has told produced
2410  * the details about the physical device - #sectors, size, etc).
2411  */
2412 static void blkfront_connect(struct blkfront_info *info)
2413 {
2414         unsigned long long sectors;
2415         unsigned long sector_size;
2416         unsigned int physical_sector_size;
2417         unsigned int binfo;
2418         char *envp[] = { "RESIZE=1", NULL };
2419         int err, i;
2420
2421         switch (info->connected) {
2422         case BLKIF_STATE_CONNECTED:
2423                 /*
2424                  * Potentially, the back-end may be signalling
2425                  * a capacity change; update the capacity.
2426                  */
2427                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2428                                    "sectors", "%Lu", &sectors);
2429                 if (XENBUS_EXIST_ERR(err))
2430                         return;
2431                 printk(KERN_INFO "Setting capacity to %Lu\n",
2432                        sectors);
2433                 set_capacity(info->gd, sectors);
2434                 revalidate_disk(info->gd);
2435                 kobject_uevent_env(&disk_to_dev(info->gd)->kobj,
2436                                    KOBJ_CHANGE, envp);
2437
2438                 return;
2439         case BLKIF_STATE_SUSPENDED:
2440                 /*
2441                  * If we are recovering from suspension, we need to wait
2442                  * for the backend to announce it's features before
2443                  * reconnecting, at least we need to know if the backend
2444                  * supports indirect descriptors, and how many.
2445                  */
2446                 blkif_recover(info);
2447                 return;
2448
2449         default:
2450                 break;
2451         }
2452
2453         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2454                 __func__, info->xbdev->otherend);
2455
2456         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2457                             "sectors", "%llu", &sectors,
2458                             "info", "%u", &binfo,
2459                             "sector-size", "%lu", &sector_size,
2460                             NULL);
2461         if (err) {
2462                 xenbus_dev_fatal(info->xbdev, err,
2463                                  "reading backend fields at %s",
2464                                  info->xbdev->otherend);
2465                 return;
2466         }
2467
2468         /*
2469          * physcial-sector-size is a newer field, so old backends may not
2470          * provide this. Assume physical sector size to be the same as
2471          * sector_size in that case.
2472          */
2473         physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2474                                                     "physical-sector-size",
2475                                                     sector_size);
2476         blkfront_gather_backend_features(info);
2477         for (i = 0; i < info->nr_rings; i++) {
2478                 err = blkfront_setup_indirect(&info->rinfo[i]);
2479                 if (err) {
2480                         xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2481                                          info->xbdev->otherend);
2482                         blkif_free(info, 0);
2483                         break;
2484                 }
2485         }
2486
2487         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2488                                   physical_sector_size);
2489         if (err) {
2490                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2491                                  info->xbdev->otherend);
2492                 goto fail;
2493         }
2494
2495         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2496
2497         /* Kick pending requests. */
2498         info->connected = BLKIF_STATE_CONNECTED;
2499         for (i = 0; i < info->nr_rings; i++)
2500                 kick_pending_request_queues(&info->rinfo[i]);
2501
2502         device_add_disk(&info->xbdev->dev, info->gd, NULL);
2503
2504         info->is_ready = 1;
2505         return;
2506
2507 fail:
2508         blkif_free(info, 0);
2509         return;
2510 }
2511
2512 /**
2513  * Callback received when the backend's state changes.
2514  */
2515 static void blkback_changed(struct xenbus_device *dev,
2516                             enum xenbus_state backend_state)
2517 {
2518         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2519
2520         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2521
2522         switch (backend_state) {
2523         case XenbusStateInitWait:
2524                 if (dev->state != XenbusStateInitialising)
2525                         break;
2526                 if (talk_to_blkback(dev, info))
2527                         break;
2528         case XenbusStateInitialising:
2529         case XenbusStateInitialised:
2530         case XenbusStateReconfiguring:
2531         case XenbusStateReconfigured:
2532         case XenbusStateUnknown:
2533                 break;
2534
2535         case XenbusStateConnected:
2536                 /*
2537                  * talk_to_blkback sets state to XenbusStateInitialised
2538                  * and blkfront_connect sets it to XenbusStateConnected
2539                  * (if connection went OK).
2540                  *
2541                  * If the backend (or toolstack) decides to poke at backend
2542                  * state (and re-trigger the watch by setting the state repeatedly
2543                  * to XenbusStateConnected (4)) we need to deal with this.
2544                  * This is allowed as this is used to communicate to the guest
2545                  * that the size of disk has changed!
2546                  */
2547                 if ((dev->state != XenbusStateInitialised) &&
2548                     (dev->state != XenbusStateConnected)) {
2549                         if (talk_to_blkback(dev, info))
2550                                 break;
2551                 }
2552
2553                 blkfront_connect(info);
2554                 break;
2555
2556         case XenbusStateClosed:
2557                 if (dev->state == XenbusStateClosed)
2558                         break;
2559                 /* fall through */
2560         case XenbusStateClosing:
2561                 if (info)
2562                         blkfront_closing(info);
2563                 break;
2564         }
2565 }
2566
2567 static int blkfront_remove(struct xenbus_device *xbdev)
2568 {
2569         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2570         struct block_device *bdev = NULL;
2571         struct gendisk *disk;
2572
2573         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2574
2575         if (!info)
2576                 return 0;
2577
2578         blkif_free(info, 0);
2579
2580         mutex_lock(&info->mutex);
2581
2582         disk = info->gd;
2583         if (disk)
2584                 bdev = bdget_disk(disk, 0);
2585
2586         info->xbdev = NULL;
2587         mutex_unlock(&info->mutex);
2588
2589         if (!bdev) {
2590                 mutex_lock(&blkfront_mutex);
2591                 free_info(info);
2592                 mutex_unlock(&blkfront_mutex);
2593                 return 0;
2594         }
2595
2596         /*
2597          * The xbdev was removed before we reached the Closed
2598          * state. See if it's safe to remove the disk. If the bdev
2599          * isn't closed yet, we let release take care of it.
2600          */
2601
2602         mutex_lock(&bdev->bd_mutex);
2603         info = disk->private_data;
2604
2605         dev_warn(disk_to_dev(disk),
2606                  "%s was hot-unplugged, %d stale handles\n",
2607                  xbdev->nodename, bdev->bd_openers);
2608
2609         if (info && !bdev->bd_openers) {
2610                 xlvbd_release_gendisk(info);
2611                 disk->private_data = NULL;
2612                 mutex_lock(&blkfront_mutex);
2613                 free_info(info);
2614                 mutex_unlock(&blkfront_mutex);
2615         }
2616
2617         mutex_unlock(&bdev->bd_mutex);
2618         bdput(bdev);
2619
2620         return 0;
2621 }
2622
2623 static int blkfront_is_ready(struct xenbus_device *dev)
2624 {
2625         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2626
2627         return info->is_ready && info->xbdev;
2628 }
2629
2630 static int blkif_open(struct block_device *bdev, fmode_t mode)
2631 {
2632         struct gendisk *disk = bdev->bd_disk;
2633         struct blkfront_info *info;
2634         int err = 0;
2635
2636         mutex_lock(&blkfront_mutex);
2637
2638         info = disk->private_data;
2639         if (!info) {
2640                 /* xbdev gone */
2641                 err = -ERESTARTSYS;
2642                 goto out;
2643         }
2644
2645         mutex_lock(&info->mutex);
2646
2647         if (!info->gd)
2648                 /* xbdev is closed */
2649                 err = -ERESTARTSYS;
2650
2651         mutex_unlock(&info->mutex);
2652
2653 out:
2654         mutex_unlock(&blkfront_mutex);
2655         return err;
2656 }
2657
2658 static void blkif_release(struct gendisk *disk, fmode_t mode)
2659 {
2660         struct blkfront_info *info = disk->private_data;
2661         struct block_device *bdev;
2662         struct xenbus_device *xbdev;
2663
2664         mutex_lock(&blkfront_mutex);
2665
2666         bdev = bdget_disk(disk, 0);
2667
2668         if (!bdev) {
2669                 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2670                 goto out_mutex;
2671         }
2672         if (bdev->bd_openers)
2673                 goto out;
2674
2675         /*
2676          * Check if we have been instructed to close. We will have
2677          * deferred this request, because the bdev was still open.
2678          */
2679
2680         mutex_lock(&info->mutex);
2681         xbdev = info->xbdev;
2682
2683         if (xbdev && xbdev->state == XenbusStateClosing) {
2684                 /* pending switch to state closed */
2685                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2686                 xlvbd_release_gendisk(info);
2687                 xenbus_frontend_closed(info->xbdev);
2688         }
2689
2690         mutex_unlock(&info->mutex);
2691
2692         if (!xbdev) {
2693                 /* sudden device removal */
2694                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2695                 xlvbd_release_gendisk(info);
2696                 disk->private_data = NULL;
2697                 free_info(info);
2698         }
2699
2700 out:
2701         bdput(bdev);
2702 out_mutex:
2703         mutex_unlock(&blkfront_mutex);
2704 }
2705
2706 static const struct block_device_operations xlvbd_block_fops =
2707 {
2708         .owner = THIS_MODULE,
2709         .open = blkif_open,
2710         .release = blkif_release,
2711         .getgeo = blkif_getgeo,
2712         .ioctl = blkif_ioctl,
2713 };
2714
2715
2716 static const struct xenbus_device_id blkfront_ids[] = {
2717         { "vbd" },
2718         { "" }
2719 };
2720
2721 static struct xenbus_driver blkfront_driver = {
2722         .ids  = blkfront_ids,
2723         .probe = blkfront_probe,
2724         .remove = blkfront_remove,
2725         .resume = blkfront_resume,
2726         .otherend_changed = blkback_changed,
2727         .is_ready = blkfront_is_ready,
2728 };
2729
2730 static void purge_persistent_grants(struct blkfront_info *info)
2731 {
2732         unsigned int i;
2733         unsigned long flags;
2734
2735         for (i = 0; i < info->nr_rings; i++) {
2736                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2737                 struct grant *gnt_list_entry, *tmp;
2738
2739                 spin_lock_irqsave(&rinfo->ring_lock, flags);
2740
2741                 if (rinfo->persistent_gnts_c == 0) {
2742                         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2743                         continue;
2744                 }
2745
2746                 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2747                                          node) {
2748                         if (gnt_list_entry->gref == GRANT_INVALID_REF ||
2749                             !gnttab_try_end_foreign_access(gnt_list_entry->gref))
2750                                 continue;
2751
2752                         list_del(&gnt_list_entry->node);
2753                         rinfo->persistent_gnts_c--;
2754                         gnt_list_entry->gref = GRANT_INVALID_REF;
2755                         list_add_tail(&gnt_list_entry->node, &rinfo->grants);
2756                 }
2757
2758                 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2759         }
2760 }
2761
2762 static void blkfront_delay_work(struct work_struct *work)
2763 {
2764         struct blkfront_info *info;
2765         bool need_schedule_work = false;
2766
2767         /*
2768          * Note that when using bounce buffers but not persistent grants
2769          * there's no need to run blkfront_delay_work because grants are
2770          * revoked in blkif_completion or else an error is reported and the
2771          * connection is closed.
2772          */
2773
2774         mutex_lock(&blkfront_mutex);
2775
2776         list_for_each_entry(info, &info_list, info_list) {
2777                 if (info->feature_persistent) {
2778                         need_schedule_work = true;
2779                         mutex_lock(&info->mutex);
2780                         purge_persistent_grants(info);
2781                         mutex_unlock(&info->mutex);
2782                 }
2783         }
2784
2785         if (need_schedule_work)
2786                 schedule_delayed_work(&blkfront_work, HZ * 10);
2787
2788         mutex_unlock(&blkfront_mutex);
2789 }
2790
2791 static int __init xlblk_init(void)
2792 {
2793         int ret;
2794         int nr_cpus = num_online_cpus();
2795
2796         if (!xen_domain())
2797                 return -ENODEV;
2798
2799         if (!xen_has_pv_disk_devices())
2800                 return -ENODEV;
2801
2802         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2803                 pr_warn("xen_blk: can't get major %d with name %s\n",
2804                         XENVBD_MAJOR, DEV_NAME);
2805                 return -ENODEV;
2806         }
2807
2808         if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2809                 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2810
2811         if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2812                 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2813                         xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2814                 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2815         }
2816
2817         if (xen_blkif_max_queues > nr_cpus) {
2818                 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2819                         xen_blkif_max_queues, nr_cpus);
2820                 xen_blkif_max_queues = nr_cpus;
2821         }
2822
2823         INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2824
2825         ret = xenbus_register_frontend(&blkfront_driver);
2826         if (ret) {
2827                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2828                 return ret;
2829         }
2830
2831         return 0;
2832 }
2833 module_init(xlblk_init);
2834
2835
2836 static void __exit xlblk_exit(void)
2837 {
2838         cancel_delayed_work_sync(&blkfront_work);
2839
2840         xenbus_unregister_driver(&blkfront_driver);
2841         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2842         kfree(minors);
2843 }
2844 module_exit(xlblk_exit);
2845
2846 MODULE_DESCRIPTION("Xen virtual block device frontend");
2847 MODULE_LICENSE("GPL");
2848 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2849 MODULE_ALIAS("xen:vbd");
2850 MODULE_ALIAS("xenblk");