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 };
  84
  85 struct grant {
  86         grant_ref_t gref;
  87         struct page *page;
  88         struct list_head node;
  89 };
  90
  91 enum blk_req_status {
  92         REQ_WAITING,
  93         REQ_DONE,
  94         REQ_ERROR,
  95         REQ_EOPNOTSUPP,
  96 };
  97
  98 struct blk_shadow {
  99         struct blkif_request req;
 100         struct request *request;
 101         struct grant **grants_used;
 102         struct grant **indirect_grants;
 103         struct scatterlist *sg;
 104         unsigned int num_sg;
 105         enum blk_req_status status;
 106
 107         #define NO_ASSOCIATED_ID ~0UL
 108         /*
 109          * Id of the sibling if we ever need 2 requests when handling a
 110          * block I/O request
 111          */
 112         unsigned long associated_id;
 113 };
 114
 115 struct blkif_req {
 116         blk_status_t    error;
 117 };
 118
 119 static inline struct blkif_req *blkif_req(struct request *rq)
 120 {
 121         return blk_mq_rq_to_pdu(rq);
 122 }
 123
 124 static DEFINE_MUTEX(blkfront_mutex);
 125 static const struct block_device_operations xlvbd_block_fops;
 126 static struct delayed_work blkfront_work;
 127 static LIST_HEAD(info_list);
 128
 129 /*
 130  * Maximum number of segments in indirect requests, the actual value used by
 131  * the frontend driver is the minimum of this value and the value provided
 132  * by the backend driver.
 133  */
 134
 135 static unsigned int xen_blkif_max_segments = 32;
 136 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
 137 MODULE_PARM_DESC(max_indirect_segments,
 138                  "Maximum amount of segments in indirect requests (default is 32)");
 139
 140 static unsigned int xen_blkif_max_queues = 4;
 141 module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
 142 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
 143
 144 /*
 145  * Maximum order of pages to be used for the shared ring between front and
 146  * backend, 4KB page granularity is used.
 147  */
 148 static unsigned int xen_blkif_max_ring_order;
 149 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
 150 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
 151
 152 #define BLK_RING_SIZE(info)     \
 153         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
 154
 155 /*
 156  * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
 157  * characters are enough. Define to 20 to keep consistent with backend.
 158  */
 159 #define RINGREF_NAME_LEN (20)
 160 /*
 161  * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
 162  */
 163 #define QUEUE_NAME_LEN (17)
 164
 165 /*
 166  *  Per-ring info.
 167  *  Every blkfront device can associate with one or more blkfront_ring_info,
 168  *  depending on how many hardware queues/rings to be used.
 169  */
 170 struct blkfront_ring_info {
 171         /* Lock to protect data in every ring buffer. */
 172         spinlock_t ring_lock;
 173         struct blkif_front_ring ring;
 174         unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
 175         unsigned int evtchn, irq;
 176         struct work_struct work;
 177         struct gnttab_free_callback callback;
 178         struct list_head indirect_pages;
 179         struct list_head grants;
 180         unsigned int persistent_gnts_c;
 181         unsigned long shadow_free;
 182         struct blkfront_info *dev_info;
 183         struct blk_shadow shadow[];
 184 };
 185
 186 /*
 187  * We have one of these per vbd, whether ide, scsi or 'other'.  They
 188  * hang in private_data off the gendisk structure. We may end up
 189  * putting all kinds of interesting stuff here :-)
 190  */
 191 struct blkfront_info
 192 {
 193         struct mutex mutex;
 194         struct xenbus_device *xbdev;
 195         struct gendisk *gd;
 196         u16 sector_size;
 197         unsigned int physical_sector_size;
 198         int vdevice;
 199         blkif_vdev_t handle;
 200         enum blkif_state connected;
 201         /* Number of pages per ring buffer. */
 202         unsigned int nr_ring_pages;
 203         struct request_queue *rq;
 204         unsigned int feature_flush:1;
 205         unsigned int feature_fua:1;
 206         unsigned int feature_discard:1;
 207         unsigned int feature_secdiscard:1;
 208         unsigned int feature_persistent:1;
 209         unsigned int discard_granularity;
 210         unsigned int discard_alignment;
 211         /* Number of 4KB segments handled */
 212         unsigned int max_indirect_segments;
 213         int is_ready;
 214         struct blk_mq_tag_set tag_set;
 215         struct blkfront_ring_info *rinfo;
 216         unsigned int nr_rings;
 217         unsigned int rinfo_size;
 218         /* Save uncomplete reqs and bios for migration. */
 219         struct list_head requests;
 220         struct bio_list bio_list;
 221         struct list_head info_list;
 222 };
 223
 224 static unsigned int nr_minors;
 225 static unsigned long *minors;
 226 static DEFINE_SPINLOCK(minor_lock);
 227
 228 #define GRANT_INVALID_REF       0
 229
 230 #define PARTS_PER_DISK          16
 231 #define PARTS_PER_EXT_DISK      256
 232
 233 #define BLKIF_MAJOR(dev) ((dev)>>8)
 234 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 235
 236 #define EXT_SHIFT 28
 237 #define EXTENDED (1<<EXT_SHIFT)
 238 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 239 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 240 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 241 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 242 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 243 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 244
 245 #define DEV_NAME        "xvd"   /* name in /dev */
 246
 247 /*
 248  * Grants are always the same size as a Xen page (i.e 4KB).
 249  * A physical segment is always the same size as a Linux page.
 250  * Number of grants per physical segment
 251  */
 252 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
 253
 254 #define GRANTS_PER_INDIRECT_FRAME \
 255         (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
 256
 257 #define INDIRECT_GREFS(_grants)         \
 258         DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
 259
 260 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 261 static void blkfront_gather_backend_features(struct blkfront_info *info);
 262 static int negotiate_mq(struct blkfront_info *info);
 263
 264 #define for_each_rinfo(info, ptr, idx)                          \
 265         for ((ptr) = (info)->rinfo, (idx) = 0;                  \
 266              (idx) < (info)->nr_rings;                          \
 267              (idx)++, (ptr) = (void *)(ptr) + (info)->rinfo_size)
 268
 269 static inline struct blkfront_ring_info *
 270 get_rinfo(const struct blkfront_info *info, unsigned int i)
 271 {
 272         BUG_ON(i >= info->nr_rings);
 273         return (void *)info->rinfo + i * info->rinfo_size;
 274 }
 275
 276 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 277 {
 278         unsigned long free = rinfo->shadow_free;
 279
 280         BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
 281         rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
 282         rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 283         return free;
 284 }
 285
 286 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
 287                               unsigned long id)
 288 {
 289         if (rinfo->shadow[id].req.u.rw.id != id)
 290                 return -EINVAL;
 291         if (rinfo->shadow[id].request == NULL)
 292                 return -EINVAL;
 293         rinfo->shadow[id].req.u.rw.id  = rinfo->shadow_free;
 294         rinfo->shadow[id].request = NULL;
 295         rinfo->shadow_free = id;
 296         return 0;
 297 }
 298
 299 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 300 {
 301         struct blkfront_info *info = rinfo->dev_info;
 302         struct page *granted_page;
 303         struct grant *gnt_list_entry, *n;
 304         int i = 0;
 305
 306         while (i < num) {
 307                 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
 308                 if (!gnt_list_entry)
 309                         goto out_of_memory;
 310
 311                 if (info->feature_persistent) {
 312                         granted_page = alloc_page(GFP_NOIO);
 313                         if (!granted_page) {
 314                                 kfree(gnt_list_entry);
 315                                 goto out_of_memory;
 316                         }
 317                         gnt_list_entry->page = granted_page;
 318                 }
 319
 320                 gnt_list_entry->gref = GRANT_INVALID_REF;
 321                 list_add(&gnt_list_entry->node, &rinfo->grants);
 322                 i++;
 323         }
 324
 325         return 0;
 326
 327 out_of_memory:
 328         list_for_each_entry_safe(gnt_list_entry, n,
 329                                  &rinfo->grants, node) {
 330                 list_del(&gnt_list_entry->node);
 331                 if (info->feature_persistent)
 332                         __free_page(gnt_list_entry->page);
 333                 kfree(gnt_list_entry);
 334                 i--;
 335         }
 336         BUG_ON(i != 0);
 337         return -ENOMEM;
 338 }
 339
 340 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
 341 {
 342         struct grant *gnt_list_entry;
 343
 344         BUG_ON(list_empty(&rinfo->grants));
 345         gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
 346                                           node);
 347         list_del(&gnt_list_entry->node);
 348
 349         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 350                 rinfo->persistent_gnts_c--;
 351
 352         return gnt_list_entry;
 353 }
 354
 355 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
 356                                         const struct blkfront_info *info)
 357 {
 358         gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
 359                                                  info->xbdev->otherend_id,
 360                                                  gnt_list_entry->page,
 361                                                  0);
 362 }
 363
 364 static struct grant *get_grant(grant_ref_t *gref_head,
 365                                unsigned long gfn,
 366                                struct blkfront_ring_info *rinfo)
 367 {
 368         struct grant *gnt_list_entry = get_free_grant(rinfo);
 369         struct blkfront_info *info = rinfo->dev_info;
 370
 371         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 372                 return gnt_list_entry;
 373
 374         /* Assign a gref to this page */
 375         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 376         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 377         if (info->feature_persistent)
 378                 grant_foreign_access(gnt_list_entry, info);
 379         else {
 380                 /* Grant access to the GFN passed by the caller */
 381                 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
 382                                                 info->xbdev->otherend_id,
 383                                                 gfn, 0);
 384         }
 385
 386         return gnt_list_entry;
 387 }
 388
 389 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
 390                                         struct blkfront_ring_info *rinfo)
 391 {
 392         struct grant *gnt_list_entry = get_free_grant(rinfo);
 393         struct blkfront_info *info = rinfo->dev_info;
 394
 395         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 396                 return gnt_list_entry;
 397
 398         /* Assign a gref to this page */
 399         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 400         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 401         if (!info->feature_persistent) {
 402                 struct page *indirect_page;
 403
 404                 /* Fetch a pre-allocated page to use for indirect grefs */
 405                 BUG_ON(list_empty(&rinfo->indirect_pages));
 406                 indirect_page = list_first_entry(&rinfo->indirect_pages,
 407                                                  struct page, lru);
 408                 list_del(&indirect_page->lru);
 409                 gnt_list_entry->page = indirect_page;
 410         }
 411         grant_foreign_access(gnt_list_entry, info);
 412
 413         return gnt_list_entry;
 414 }
 415
 416 static const char *op_name(int op)
 417 {
 418         static const char *const names[] = {
 419                 [BLKIF_OP_READ] = "read",
 420                 [BLKIF_OP_WRITE] = "write",
 421                 [BLKIF_OP_WRITE_BARRIER] = "barrier",
 422                 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
 423                 [BLKIF_OP_DISCARD] = "discard" };
 424
 425         if (op < 0 || op >= ARRAY_SIZE(names))
 426                 return "unknown";
 427
 428         if (!names[op])
 429                 return "reserved";
 430
 431         return names[op];
 432 }
 433 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 434 {
 435         unsigned int end = minor + nr;
 436         int rc;
 437
 438         if (end > nr_minors) {
 439                 unsigned long *bitmap, *old;
 440
 441                 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 442                                  GFP_KERNEL);
 443                 if (bitmap == NULL)
 444                         return -ENOMEM;
 445
 446                 spin_lock(&minor_lock);
 447                 if (end > nr_minors) {
 448                         old = minors;
 449                         memcpy(bitmap, minors,
 450                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 451                         minors = bitmap;
 452                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 453                 } else
 454                         old = bitmap;
 455                 spin_unlock(&minor_lock);
 456                 kfree(old);
 457         }
 458
 459         spin_lock(&minor_lock);
 460         if (find_next_bit(minors, end, minor) >= end) {
 461                 bitmap_set(minors, minor, nr);
 462                 rc = 0;
 463         } else
 464                 rc = -EBUSY;
 465         spin_unlock(&minor_lock);
 466
 467         return rc;
 468 }
 469
 470 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 471 {
 472         unsigned int end = minor + nr;
 473
 474         BUG_ON(end > nr_minors);
 475         spin_lock(&minor_lock);
 476         bitmap_clear(minors,  minor, nr);
 477         spin_unlock(&minor_lock);
 478 }
 479
 480 static void blkif_restart_queue_callback(void *arg)
 481 {
 482         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
 483         schedule_work(&rinfo->work);
 484 }
 485
 486 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 487 {
 488         /* We don't have real geometry info, but let's at least return
 489            values consistent with the size of the device */
 490         sector_t nsect = get_capacity(bd->bd_disk);
 491         sector_t cylinders = nsect;
 492
 493         hg->heads = 0xff;
 494         hg->sectors = 0x3f;
 495         sector_div(cylinders, hg->heads * hg->sectors);
 496         hg->cylinders = cylinders;
 497         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 498                 hg->cylinders = 0xffff;
 499         return 0;
 500 }
 501
 502 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 503                        unsigned command, unsigned long argument)
 504 {
 505         struct blkfront_info *info = bdev->bd_disk->private_data;
 506         int i;
 507
 508         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 509                 command, (long)argument);
 510
 511         switch (command) {
 512         case CDROMMULTISESSION:
 513                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 514                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 515                         if (put_user(0, (char __user *)(argument + i)))
 516                                 return -EFAULT;
 517                 return 0;
 518
 519         case CDROM_GET_CAPABILITY: {
 520                 struct gendisk *gd = info->gd;
 521                 if (gd->flags & GENHD_FL_CD)
 522                         return 0;
 523                 return -EINVAL;
 524         }
 525
 526         default:
 527                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 528                   command);*/
 529                 return -EINVAL; /* same return as native Linux */
 530         }
 531
 532         return 0;
 533 }
 534
 535 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 536                                             struct request *req,
 537                                             struct blkif_request **ring_req)
 538 {
 539         unsigned long id;
 540
 541         *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
 542         rinfo->ring.req_prod_pvt++;
 543
 544         id = get_id_from_freelist(rinfo);
 545         rinfo->shadow[id].request = req;
 546         rinfo->shadow[id].status = REQ_WAITING;
 547         rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
 548
 549         (*ring_req)->u.rw.id = id;
 550
 551         return id;
 552 }
 553
 554 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
 555 {
 556         struct blkfront_info *info = rinfo->dev_info;
 557         struct blkif_request *ring_req;
 558         unsigned long id;
 559
 560         /* Fill out a communications ring structure. */
 561         id = blkif_ring_get_request(rinfo, req, &ring_req);
 562
 563         ring_req->operation = BLKIF_OP_DISCARD;
 564         ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
 565         ring_req->u.discard.id = id;
 566         ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
 567         if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
 568                 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
 569         else
 570                 ring_req->u.discard.flag = 0;
 571
 572         /* Keep a private copy so we can reissue requests when recovering. */
 573         rinfo->shadow[id].req = *ring_req;
 574
 575         return 0;
 576 }
 577
 578 struct setup_rw_req {
 579         unsigned int grant_idx;
 580         struct blkif_request_segment *segments;
 581         struct blkfront_ring_info *rinfo;
 582         struct blkif_request *ring_req;
 583         grant_ref_t gref_head;
 584         unsigned int id;
 585         /* Only used when persistent grant is used and it's a read request */
 586         bool need_copy;
 587         unsigned int bvec_off;
 588         char *bvec_data;
 589
 590         bool require_extra_req;
 591         struct blkif_request *extra_ring_req;
 592 };
 593
 594 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
 595                                      unsigned int len, void *data)
 596 {
 597         struct setup_rw_req *setup = data;
 598         int n, ref;
 599         struct grant *gnt_list_entry;
 600         unsigned int fsect, lsect;
 601         /* Convenient aliases */
 602         unsigned int grant_idx = setup->grant_idx;
 603         struct blkif_request *ring_req = setup->ring_req;
 604         struct blkfront_ring_info *rinfo = setup->rinfo;
 605         /*
 606          * We always use the shadow of the first request to store the list
 607          * of grant associated to the block I/O request. This made the
 608          * completion more easy to handle even if the block I/O request is
 609          * split.
 610          */
 611         struct blk_shadow *shadow = &rinfo->shadow[setup->id];
 612
 613         if (unlikely(setup->require_extra_req &&
 614                      grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
 615                 /*
 616                  * We are using the second request, setup grant_idx
 617                  * to be the index of the segment array.
 618                  */
 619                 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
 620                 ring_req = setup->extra_ring_req;
 621         }
 622
 623         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 624             (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
 625                 if (setup->segments)
 626                         kunmap_atomic(setup->segments);
 627
 628                 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
 629                 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
 630                 shadow->indirect_grants[n] = gnt_list_entry;
 631                 setup->segments = kmap_atomic(gnt_list_entry->page);
 632                 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 633         }
 634
 635         gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
 636         ref = gnt_list_entry->gref;
 637         /*
 638          * All the grants are stored in the shadow of the first
 639          * request. Therefore we have to use the global index.
 640          */
 641         shadow->grants_used[setup->grant_idx] = gnt_list_entry;
 642
 643         if (setup->need_copy) {
 644                 void *shared_data;
 645
 646                 shared_data = kmap_atomic(gnt_list_entry->page);
 647                 /*
 648                  * this does not wipe data stored outside the
 649                  * range sg->offset..sg->offset+sg->length.
 650                  * Therefore, blkback *could* see data from
 651                  * previous requests. This is OK as long as
 652                  * persistent grants are shared with just one
 653                  * domain. It may need refactoring if this
 654                  * changes
 655                  */
 656                 memcpy(shared_data + offset,
 657                        setup->bvec_data + setup->bvec_off,
 658                        len);
 659
 660                 kunmap_atomic(shared_data);
 661                 setup->bvec_off += len;
 662         }
 663
 664         fsect = offset >> 9;
 665         lsect = fsect + (len >> 9) - 1;
 666         if (ring_req->operation != BLKIF_OP_INDIRECT) {
 667                 ring_req->u.rw.seg[grant_idx] =
 668                         (struct blkif_request_segment) {
 669                                 .gref       = ref,
 670                                 .first_sect = fsect,
 671                                 .last_sect  = lsect };
 672         } else {
 673                 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
 674                         (struct blkif_request_segment) {
 675                                 .gref       = ref,
 676                                 .first_sect = fsect,
 677                                 .last_sect  = lsect };
 678         }
 679
 680         (setup->grant_idx)++;
 681 }
 682
 683 static void blkif_setup_extra_req(struct blkif_request *first,
 684                                   struct blkif_request *second)
 685 {
 686         uint16_t nr_segments = first->u.rw.nr_segments;
 687
 688         /*
 689          * The second request is only present when the first request uses
 690          * all its segments. It's always the continuity of the first one.
 691          */
 692         first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 693
 694         second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
 695         second->u.rw.sector_number = first->u.rw.sector_number +
 696                 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
 697
 698         second->u.rw.handle = first->u.rw.handle;
 699         second->operation = first->operation;
 700 }
 701
 702 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
 703 {
 704         struct blkfront_info *info = rinfo->dev_info;
 705         struct blkif_request *ring_req, *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->feature_persistent,
 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, &ring_req);
 751
 752         num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 753         num_grant = 0;
 754         /* Calculate the number of grant used */
 755         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
 756                num_grant += gnttab_count_grant(sg->offset, sg->length);
 757
 758         require_extra_req = info->max_indirect_segments == 0 &&
 759                 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
 760         BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
 761
 762         rinfo->shadow[id].num_sg = num_sg;
 763         if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
 764             likely(!require_extra_req)) {
 765                 /*
 766                  * The indirect operation can only be a BLKIF_OP_READ or
 767                  * BLKIF_OP_WRITE
 768                  */
 769                 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
 770                 ring_req->operation = BLKIF_OP_INDIRECT;
 771                 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
 772                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 773                 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
 774                 ring_req->u.indirect.handle = info->handle;
 775                 ring_req->u.indirect.nr_segments = num_grant;
 776         } else {
 777                 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 778                 ring_req->u.rw.handle = info->handle;
 779                 ring_req->operation = rq_data_dir(req) ?
 780                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 781                 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
 782                         /*
 783                          * Ideally we can do an unordered flush-to-disk.
 784                          * In case the backend onlysupports barriers, use that.
 785                          * A barrier request a superset of FUA, so we can
 786                          * implement it the same way.  (It's also a FLUSH+FUA,
 787                          * since it is guaranteed ordered WRT previous writes.)
 788                          */
 789                         if (info->feature_flush && info->feature_fua)
 790                                 ring_req->operation =
 791                                         BLKIF_OP_WRITE_BARRIER;
 792                         else if (info->feature_flush)
 793                                 ring_req->operation =
 794                                         BLKIF_OP_FLUSH_DISKCACHE;
 795                         else
 796                                 ring_req->operation = 0;
 797                 }
 798                 ring_req->u.rw.nr_segments = num_grant;
 799                 if (unlikely(require_extra_req)) {
 800                         extra_id = blkif_ring_get_request(rinfo, req,
 801                                                           &extra_ring_req);
 802                         /*
 803                          * Only the first request contains the scatter-gather
 804                          * list.
 805                          */
 806                         rinfo->shadow[extra_id].num_sg = 0;
 807
 808                         blkif_setup_extra_req(ring_req, extra_ring_req);
 809
 810                         /* Link the 2 requests together */
 811                         rinfo->shadow[extra_id].associated_id = id;
 812                         rinfo->shadow[id].associated_id = extra_id;
 813                 }
 814         }
 815
 816         setup.ring_req = ring_req;
 817         setup.id = id;
 818
 819         setup.require_extra_req = require_extra_req;
 820         if (unlikely(require_extra_req))
 821                 setup.extra_ring_req = extra_ring_req;
 822
 823         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
 824                 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
 825
 826                 if (setup.need_copy) {
 827                         setup.bvec_off = sg->offset;
 828                         setup.bvec_data = kmap_atomic(sg_page(sg));
 829                 }
 830
 831                 gnttab_foreach_grant_in_range(sg_page(sg),
 832                                               sg->offset,
 833                                               sg->length,
 834                                               blkif_setup_rw_req_grant,
 835                                               &setup);
 836
 837                 if (setup.need_copy)
 838                         kunmap_atomic(setup.bvec_data);
 839         }
 840         if (setup.segments)
 841                 kunmap_atomic(setup.segments);
 842
 843         /* Keep a private copy so we can reissue requests when recovering. */
 844         rinfo->shadow[id].req = *ring_req;
 845         if (unlikely(require_extra_req))
 846                 rinfo->shadow[extra_id].req = *extra_ring_req;
 847
 848         if (new_persistent_gnts)
 849                 gnttab_free_grant_references(setup.gref_head);
 850
 851         return 0;
 852 }
 853
 854 /*
 855  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 856  * and writes are handled as expected.
 857  *
 858  * @req: a request struct
 859  */
 860 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
 861 {
 862         if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
 863                 return 1;
 864
 865         if (unlikely(req_op(req) == REQ_OP_DISCARD ||
 866                      req_op(req) == REQ_OP_SECURE_ERASE))
 867                 return blkif_queue_discard_req(req, rinfo);
 868         else
 869                 return blkif_queue_rw_req(req, rinfo);
 870 }
 871
 872 static inline void flush_requests(struct blkfront_ring_info *rinfo)
 873 {
 874         int notify;
 875
 876         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
 877
 878         if (notify)
 879                 notify_remote_via_irq(rinfo->irq);
 880 }
 881
 882 static inline bool blkif_request_flush_invalid(struct request *req,
 883                                                struct blkfront_info *info)
 884 {
 885         return (blk_rq_is_passthrough(req) ||
 886                 ((req_op(req) == REQ_OP_FLUSH) &&
 887                  !info->feature_flush) ||
 888                 ((req->cmd_flags & REQ_FUA) &&
 889                  !info->feature_fua));
 890 }
 891
 892 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
 893                           const struct blk_mq_queue_data *qd)
 894 {
 895         unsigned long flags;
 896         int qid = hctx->queue_num;
 897         struct blkfront_info *info = hctx->queue->queuedata;
 898         struct blkfront_ring_info *rinfo = NULL;
 899
 900         rinfo = get_rinfo(info, qid);
 901         blk_mq_start_request(qd->rq);
 902         spin_lock_irqsave(&rinfo->ring_lock, flags);
 903         if (RING_FULL(&rinfo->ring))
 904                 goto out_busy;
 905
 906         if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
 907                 goto out_err;
 908
 909         if (blkif_queue_request(qd->rq, rinfo))
 910                 goto out_busy;
 911
 912         flush_requests(rinfo);
 913         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 914         return BLK_STS_OK;
 915
 916 out_err:
 917         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 918         return BLK_STS_IOERR;
 919
 920 out_busy:
 921         blk_mq_stop_hw_queue(hctx);
 922         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 923         return BLK_STS_DEV_RESOURCE;
 924 }
 925
 926 static void blkif_complete_rq(struct request *rq)
 927 {
 928         blk_mq_end_request(rq, blkif_req(rq)->error);
 929 }
 930
 931 static const struct blk_mq_ops blkfront_mq_ops = {
 932         .queue_rq = blkif_queue_rq,
 933         .complete = blkif_complete_rq,
 934 };
 935
 936 static void blkif_set_queue_limits(struct blkfront_info *info)
 937 {
 938         struct request_queue *rq = info->rq;
 939         struct gendisk *gd = info->gd;
 940         unsigned int segments = info->max_indirect_segments ? :
 941                                 BLKIF_MAX_SEGMENTS_PER_REQUEST;
 942
 943         blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
 944
 945         if (info->feature_discard) {
 946                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
 947                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
 948                 rq->limits.discard_granularity = info->discard_granularity ?:
 949                                                  info->physical_sector_size;
 950                 rq->limits.discard_alignment = info->discard_alignment;
 951                 if (info->feature_secdiscard)
 952                         blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
 953         }
 954
 955         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 956         blk_queue_logical_block_size(rq, info->sector_size);
 957         blk_queue_physical_block_size(rq, info->physical_sector_size);
 958         blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
 959
 960         /* Each segment in a request is up to an aligned page in size. */
 961         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 962         blk_queue_max_segment_size(rq, PAGE_SIZE);
 963
 964         /* Ensure a merged request will fit in a single I/O ring slot. */
 965         blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
 966
 967         /* Make sure buffer addresses are sector-aligned. */
 968         blk_queue_dma_alignment(rq, 511);
 969 }
 970
 971 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 972                                 unsigned int physical_sector_size)
 973 {
 974         struct request_queue *rq;
 975         struct blkfront_info *info = gd->private_data;
 976
 977         memset(&info->tag_set, 0, sizeof(info->tag_set));
 978         info->tag_set.ops = &blkfront_mq_ops;
 979         info->tag_set.nr_hw_queues = info->nr_rings;
 980         if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
 981                 /*
 982                  * When indirect descriptior is not supported, the I/O request
 983                  * will be split between multiple request in the ring.
 984                  * To avoid problems when sending the request, divide by
 985                  * 2 the depth of the queue.
 986                  */
 987                 info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
 988         } else
 989                 info->tag_set.queue_depth = BLK_RING_SIZE(info);
 990         info->tag_set.numa_node = NUMA_NO_NODE;
 991         info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 992         info->tag_set.cmd_size = sizeof(struct blkif_req);
 993         info->tag_set.driver_data = info;
 994
 995         if (blk_mq_alloc_tag_set(&info->tag_set))
 996                 return -EINVAL;
 997         rq = blk_mq_init_queue(&info->tag_set);
 998         if (IS_ERR(rq)) {
 999                 blk_mq_free_tag_set(&info->tag_set);
1000                 return PTR_ERR(rq);
1001         }
1002
1003         rq->queuedata = info;
1004         info->rq = gd->queue = rq;
1005         info->gd = gd;
1006         info->sector_size = sector_size;
1007         info->physical_sector_size = physical_sector_size;
1008         blkif_set_queue_limits(info);
1009
1010         return 0;
1011 }
1012
1013 static const char *flush_info(struct blkfront_info *info)
1014 {
1015         if (info->feature_flush && info->feature_fua)
1016                 return "barrier: enabled;";
1017         else if (info->feature_flush)
1018                 return "flush diskcache: enabled;";
1019         else
1020                 return "barrier or flush: disabled;";
1021 }
1022
1023 static void xlvbd_flush(struct blkfront_info *info)
1024 {
1025         blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
1026                               info->feature_fua ? true : false);
1027         pr_info("blkfront: %s: %s %s %s %s %s\n",
1028                 info->gd->disk_name, flush_info(info),
1029                 "persistent grants:", info->feature_persistent ?
1030                 "enabled;" : "disabled;", "indirect descriptors:",
1031                 info->max_indirect_segments ? "enabled;" : "disabled;");
1032 }
1033
1034 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1035 {
1036         int major;
1037         major = BLKIF_MAJOR(vdevice);
1038         *minor = BLKIF_MINOR(vdevice);
1039         switch (major) {
1040                 case XEN_IDE0_MAJOR:
1041                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1042                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
1043                                 EMULATED_HD_DISK_MINOR_OFFSET;
1044                         break;
1045                 case XEN_IDE1_MAJOR:
1046                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1047                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1048                                 EMULATED_HD_DISK_MINOR_OFFSET;
1049                         break;
1050                 case XEN_SCSI_DISK0_MAJOR:
1051                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1052                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1053                         break;
1054                 case XEN_SCSI_DISK1_MAJOR:
1055                 case XEN_SCSI_DISK2_MAJOR:
1056                 case XEN_SCSI_DISK3_MAJOR:
1057                 case XEN_SCSI_DISK4_MAJOR:
1058                 case XEN_SCSI_DISK5_MAJOR:
1059                 case XEN_SCSI_DISK6_MAJOR:
1060                 case XEN_SCSI_DISK7_MAJOR:
1061                         *offset = (*minor / PARTS_PER_DISK) +
1062                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1063                                 EMULATED_SD_DISK_NAME_OFFSET;
1064                         *minor = *minor +
1065                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1066                                 EMULATED_SD_DISK_MINOR_OFFSET;
1067                         break;
1068                 case XEN_SCSI_DISK8_MAJOR:
1069                 case XEN_SCSI_DISK9_MAJOR:
1070                 case XEN_SCSI_DISK10_MAJOR:
1071                 case XEN_SCSI_DISK11_MAJOR:
1072                 case XEN_SCSI_DISK12_MAJOR:
1073                 case XEN_SCSI_DISK13_MAJOR:
1074                 case XEN_SCSI_DISK14_MAJOR:
1075                 case XEN_SCSI_DISK15_MAJOR:
1076                         *offset = (*minor / PARTS_PER_DISK) +
1077                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1078                                 EMULATED_SD_DISK_NAME_OFFSET;
1079                         *minor = *minor +
1080                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1081                                 EMULATED_SD_DISK_MINOR_OFFSET;
1082                         break;
1083                 case XENVBD_MAJOR:
1084                         *offset = *minor / PARTS_PER_DISK;
1085                         break;
1086                 default:
1087                         printk(KERN_WARNING "blkfront: your disk configuration is "
1088                                         "incorrect, please use an xvd device instead\n");
1089                         return -ENODEV;
1090         }
1091         return 0;
1092 }
1093
1094 static char *encode_disk_name(char *ptr, unsigned int n)
1095 {
1096         if (n >= 26)
1097                 ptr = encode_disk_name(ptr, n / 26 - 1);
1098         *ptr = 'a' + n % 26;
1099         return ptr + 1;
1100 }
1101
1102 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1103                                struct blkfront_info *info,
1104                                u16 vdisk_info, u16 sector_size,
1105                                unsigned int physical_sector_size)
1106 {
1107         struct gendisk *gd;
1108         int nr_minors = 1;
1109         int err;
1110         unsigned int offset;
1111         int minor;
1112         int nr_parts;
1113         char *ptr;
1114
1115         BUG_ON(info->gd != NULL);
1116         BUG_ON(info->rq != NULL);
1117
1118         if ((info->vdevice>>EXT_SHIFT) > 1) {
1119                 /* this is above the extended range; something is wrong */
1120                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1121                 return -ENODEV;
1122         }
1123
1124         if (!VDEV_IS_EXTENDED(info->vdevice)) {
1125                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1126                 if (err)
1127                         return err;
1128                 nr_parts = PARTS_PER_DISK;
1129         } else {
1130                 minor = BLKIF_MINOR_EXT(info->vdevice);
1131                 nr_parts = PARTS_PER_EXT_DISK;
1132                 offset = minor / nr_parts;
1133                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1134                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1135                                         "emulated IDE disks,\n\t choose an xvd device name"
1136                                         "from xvde on\n", info->vdevice);
1137         }
1138         if (minor >> MINORBITS) {
1139                 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1140                         info->vdevice, minor);
1141                 return -ENODEV;
1142         }
1143
1144         if ((minor % nr_parts) == 0)
1145                 nr_minors = nr_parts;
1146
1147         err = xlbd_reserve_minors(minor, nr_minors);
1148         if (err)
1149                 goto out;
1150         err = -ENODEV;
1151
1152         gd = alloc_disk(nr_minors);
1153         if (gd == NULL)
1154                 goto release;
1155
1156         strcpy(gd->disk_name, DEV_NAME);
1157         ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1158         BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1159         if (nr_minors > 1)
1160                 *ptr = 0;
1161         else
1162                 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1163                          "%d", minor & (nr_parts - 1));
1164
1165         gd->major = XENVBD_MAJOR;
1166         gd->first_minor = minor;
1167         gd->fops = &xlvbd_block_fops;
1168         gd->private_data = info;
1169         set_capacity(gd, capacity);
1170
1171         if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
1172                 del_gendisk(gd);
1173                 goto release;
1174         }
1175
1176         xlvbd_flush(info);
1177
1178         if (vdisk_info & VDISK_READONLY)
1179                 set_disk_ro(gd, 1);
1180
1181         if (vdisk_info & VDISK_REMOVABLE)
1182                 gd->flags |= GENHD_FL_REMOVABLE;
1183
1184         if (vdisk_info & VDISK_CDROM)
1185                 gd->flags |= GENHD_FL_CD;
1186
1187         return 0;
1188
1189  release:
1190         xlbd_release_minors(minor, nr_minors);
1191  out:
1192         return err;
1193 }
1194
1195 static void xlvbd_release_gendisk(struct blkfront_info *info)
1196 {
1197         unsigned int minor, nr_minors, i;
1198         struct blkfront_ring_info *rinfo;
1199
1200         if (info->rq == NULL)
1201                 return;
1202
1203         /* No more blkif_request(). */
1204         blk_mq_stop_hw_queues(info->rq);
1205
1206         for_each_rinfo(info, rinfo, i) {
1207                 /* No more gnttab callback work. */
1208                 gnttab_cancel_free_callback(&rinfo->callback);
1209
1210                 /* Flush gnttab callback work. Must be done with no locks held. */
1211                 flush_work(&rinfo->work);
1212         }
1213
1214         del_gendisk(info->gd);
1215
1216         minor = info->gd->first_minor;
1217         nr_minors = info->gd->minors;
1218         xlbd_release_minors(minor, nr_minors);
1219
1220         blk_cleanup_queue(info->rq);
1221         blk_mq_free_tag_set(&info->tag_set);
1222         info->rq = NULL;
1223
1224         put_disk(info->gd);
1225         info->gd = NULL;
1226 }
1227
1228 /* Already hold rinfo->ring_lock. */
1229 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1230 {
1231         if (!RING_FULL(&rinfo->ring))
1232                 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1233 }
1234
1235 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1236 {
1237         unsigned long flags;
1238
1239         spin_lock_irqsave(&rinfo->ring_lock, flags);
1240         kick_pending_request_queues_locked(rinfo);
1241         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1242 }
1243
1244 static void blkif_restart_queue(struct work_struct *work)
1245 {
1246         struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1247
1248         if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1249                 kick_pending_request_queues(rinfo);
1250 }
1251
1252 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1253 {
1254         struct grant *persistent_gnt, *n;
1255         struct blkfront_info *info = rinfo->dev_info;
1256         int i, j, segs;
1257
1258         /*
1259          * Remove indirect pages, this only happens when using indirect
1260          * descriptors but not persistent grants
1261          */
1262         if (!list_empty(&rinfo->indirect_pages)) {
1263                 struct page *indirect_page, *n;
1264
1265                 BUG_ON(info->feature_persistent);
1266                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1267                         list_del(&indirect_page->lru);
1268                         __free_page(indirect_page);
1269                 }
1270         }
1271
1272         /* Remove all persistent grants. */
1273         if (!list_empty(&rinfo->grants)) {
1274                 list_for_each_entry_safe(persistent_gnt, n,
1275                                          &rinfo->grants, node) {
1276                         list_del(&persistent_gnt->node);
1277                         if (persistent_gnt->gref != GRANT_INVALID_REF) {
1278                                 gnttab_end_foreign_access(persistent_gnt->gref,
1279                                                           0, 0UL);
1280                                 rinfo->persistent_gnts_c--;
1281                         }
1282                         if (info->feature_persistent)
1283                                 __free_page(persistent_gnt->page);
1284                         kfree(persistent_gnt);
1285                 }
1286         }
1287         BUG_ON(rinfo->persistent_gnts_c != 0);
1288
1289         for (i = 0; i < BLK_RING_SIZE(info); i++) {
1290                 /*
1291                  * Clear persistent grants present in requests already
1292                  * on the shared ring
1293                  */
1294                 if (!rinfo->shadow[i].request)
1295                         goto free_shadow;
1296
1297                 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1298                        rinfo->shadow[i].req.u.indirect.nr_segments :
1299                        rinfo->shadow[i].req.u.rw.nr_segments;
1300                 for (j = 0; j < segs; j++) {
1301                         persistent_gnt = rinfo->shadow[i].grants_used[j];
1302                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1303                         if (info->feature_persistent)
1304                                 __free_page(persistent_gnt->page);
1305                         kfree(persistent_gnt);
1306                 }
1307
1308                 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1309                         /*
1310                          * If this is not an indirect operation don't try to
1311                          * free indirect segments
1312                          */
1313                         goto free_shadow;
1314
1315                 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1316                         persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1317                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1318                         __free_page(persistent_gnt->page);
1319                         kfree(persistent_gnt);
1320                 }
1321
1322 free_shadow:
1323                 kvfree(rinfo->shadow[i].grants_used);
1324                 rinfo->shadow[i].grants_used = NULL;
1325                 kvfree(rinfo->shadow[i].indirect_grants);
1326                 rinfo->shadow[i].indirect_grants = NULL;
1327                 kvfree(rinfo->shadow[i].sg);
1328                 rinfo->shadow[i].sg = NULL;
1329         }
1330
1331         /* No more gnttab callback work. */
1332         gnttab_cancel_free_callback(&rinfo->callback);
1333
1334         /* Flush gnttab callback work. Must be done with no locks held. */
1335         flush_work(&rinfo->work);
1336
1337         /* Free resources associated with old device channel. */
1338         for (i = 0; i < info->nr_ring_pages; i++) {
1339                 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1340                         gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1341                         rinfo->ring_ref[i] = GRANT_INVALID_REF;
1342                 }
1343         }
1344         free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
1345         rinfo->ring.sring = NULL;
1346
1347         if (rinfo->irq)
1348                 unbind_from_irqhandler(rinfo->irq, rinfo);
1349         rinfo->evtchn = rinfo->irq = 0;
1350 }
1351
1352 static void blkif_free(struct blkfront_info *info, int suspend)
1353 {
1354         unsigned int i;
1355         struct blkfront_ring_info *rinfo;
1356
1357         /* Prevent new requests being issued until we fix things up. */
1358         info->connected = suspend ?
1359                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1360         /* No more blkif_request(). */
1361         if (info->rq)
1362                 blk_mq_stop_hw_queues(info->rq);
1363
1364         for_each_rinfo(info, rinfo, i)
1365                 blkif_free_ring(rinfo);
1366
1367         kvfree(info->rinfo);
1368         info->rinfo = NULL;
1369         info->nr_rings = 0;
1370 }
1371
1372 struct copy_from_grant {
1373         const struct blk_shadow *s;
1374         unsigned int grant_idx;
1375         unsigned int bvec_offset;
1376         char *bvec_data;
1377 };
1378
1379 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1380                                   unsigned int len, void *data)
1381 {
1382         struct copy_from_grant *info = data;
1383         char *shared_data;
1384         /* Convenient aliases */
1385         const struct blk_shadow *s = info->s;
1386
1387         shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1388
1389         memcpy(info->bvec_data + info->bvec_offset,
1390                shared_data + offset, len);
1391
1392         info->bvec_offset += len;
1393         info->grant_idx++;
1394
1395         kunmap_atomic(shared_data);
1396 }
1397
1398 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1399 {
1400         switch (rsp)
1401         {
1402         case BLKIF_RSP_OKAY:
1403                 return REQ_DONE;
1404         case BLKIF_RSP_EOPNOTSUPP:
1405                 return REQ_EOPNOTSUPP;
1406         case BLKIF_RSP_ERROR:
1407         default:
1408                 return REQ_ERROR;
1409         }
1410 }
1411
1412 /*
1413  * Get the final status of the block request based on two ring response
1414  */
1415 static int blkif_get_final_status(enum blk_req_status s1,
1416                                   enum blk_req_status s2)
1417 {
1418         BUG_ON(s1 == REQ_WAITING);
1419         BUG_ON(s2 == REQ_WAITING);
1420
1421         if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1422                 return BLKIF_RSP_ERROR;
1423         else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1424                 return BLKIF_RSP_EOPNOTSUPP;
1425         return BLKIF_RSP_OKAY;
1426 }
1427
1428 static bool blkif_completion(unsigned long *id,
1429                              struct blkfront_ring_info *rinfo,
1430                              struct blkif_response *bret)
1431 {
1432         int i = 0;
1433         struct scatterlist *sg;
1434         int num_sg, num_grant;
1435         struct blkfront_info *info = rinfo->dev_info;
1436         struct blk_shadow *s = &rinfo->shadow[*id];
1437         struct copy_from_grant data = {
1438                 .grant_idx = 0,
1439         };
1440
1441         num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1442                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1443
1444         /* The I/O request may be split in two. */
1445         if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1446                 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1447
1448                 /* Keep the status of the current response in shadow. */
1449                 s->status = blkif_rsp_to_req_status(bret->status);
1450
1451                 /* Wait the second response if not yet here. */
1452                 if (s2->status == REQ_WAITING)
1453                         return false;
1454
1455                 bret->status = blkif_get_final_status(s->status,
1456                                                       s2->status);
1457
1458                 /*
1459                  * All the grants is stored in the first shadow in order
1460                  * to make the completion code simpler.
1461                  */
1462                 num_grant += s2->req.u.rw.nr_segments;
1463
1464                 /*
1465                  * The two responses may not come in order. Only the
1466                  * first request will store the scatter-gather list.
1467                  */
1468                 if (s2->num_sg != 0) {
1469                         /* Update "id" with the ID of the first response. */
1470                         *id = s->associated_id;
1471                         s = s2;
1472                 }
1473
1474                 /*
1475                  * We don't need anymore the second request, so recycling
1476                  * it now.
1477                  */
1478                 if (add_id_to_freelist(rinfo, s->associated_id))
1479                         WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1480                              info->gd->disk_name, s->associated_id);
1481         }
1482
1483         data.s = s;
1484         num_sg = s->num_sg;
1485
1486         if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1487                 for_each_sg(s->sg, sg, num_sg, i) {
1488                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1489
1490                         data.bvec_offset = sg->offset;
1491                         data.bvec_data = kmap_atomic(sg_page(sg));
1492
1493                         gnttab_foreach_grant_in_range(sg_page(sg),
1494                                                       sg->offset,
1495                                                       sg->length,
1496                                                       blkif_copy_from_grant,
1497                                                       &data);
1498
1499                         kunmap_atomic(data.bvec_data);
1500                 }
1501         }
1502         /* Add the persistent grant into the list of free grants */
1503         for (i = 0; i < num_grant; i++) {
1504                 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1505                         /*
1506                          * If the grant is still mapped by the backend (the
1507                          * backend has chosen to make this grant persistent)
1508                          * we add it at the head of the list, so it will be
1509                          * reused first.
1510                          */
1511                         if (!info->feature_persistent)
1512                                 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1513                                                      s->grants_used[i]->gref);
1514                         list_add(&s->grants_used[i]->node, &rinfo->grants);
1515                         rinfo->persistent_gnts_c++;
1516                 } else {
1517                         /*
1518                          * If the grant is not mapped by the backend we end the
1519                          * foreign access and add it to the tail of the list,
1520                          * so it will not be picked again unless we run out of
1521                          * persistent grants.
1522                          */
1523                         gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1524                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1525                         list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1526                 }
1527         }
1528         if (s->req.operation == BLKIF_OP_INDIRECT) {
1529                 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1530                         if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1531                                 if (!info->feature_persistent)
1532                                         pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1533                                                              s->indirect_grants[i]->gref);
1534                                 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1535                                 rinfo->persistent_gnts_c++;
1536                         } else {
1537                                 struct page *indirect_page;
1538
1539                                 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1540                                 /*
1541                                  * Add the used indirect page back to the list of
1542                                  * available pages for indirect grefs.
1543                                  */
1544                                 if (!info->feature_persistent) {
1545                                         indirect_page = s->indirect_grants[i]->page;
1546                                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
1547                                 }
1548                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1549                                 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1550                         }
1551                 }
1552         }
1553
1554         return true;
1555 }
1556
1557 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1558 {
1559         struct request *req;
1560         struct blkif_response *bret;
1561         RING_IDX i, rp;
1562         unsigned long flags;
1563         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1564         struct blkfront_info *info = rinfo->dev_info;
1565
1566         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1567                 return IRQ_HANDLED;
1568
1569         spin_lock_irqsave(&rinfo->ring_lock, flags);
1570  again:
1571         rp = rinfo->ring.sring->rsp_prod;
1572         rmb(); /* Ensure we see queued responses up to 'rp'. */
1573
1574         for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1575                 unsigned long id;
1576
1577                 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1578                 id   = bret->id;
1579                 /*
1580                  * The backend has messed up and given us an id that we would
1581                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1582                  * look in get_id_from_freelist.
1583                  */
1584                 if (id >= BLK_RING_SIZE(info)) {
1585                         WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1586                              info->gd->disk_name, op_name(bret->operation), id);
1587                         /* We can't safely get the 'struct request' as
1588                          * the id is busted. */
1589                         continue;
1590                 }
1591                 req  = rinfo->shadow[id].request;
1592
1593                 if (bret->operation != BLKIF_OP_DISCARD) {
1594                         /*
1595                          * We may need to wait for an extra response if the
1596                          * I/O request is split in 2
1597                          */
1598                         if (!blkif_completion(&id, rinfo, bret))
1599                                 continue;
1600                 }
1601
1602                 if (add_id_to_freelist(rinfo, id)) {
1603                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1604                              info->gd->disk_name, op_name(bret->operation), id);
1605                         continue;
1606                 }
1607
1608                 if (bret->status == BLKIF_RSP_OKAY)
1609                         blkif_req(req)->error = BLK_STS_OK;
1610                 else
1611                         blkif_req(req)->error = BLK_STS_IOERR;
1612
1613                 switch (bret->operation) {
1614                 case BLKIF_OP_DISCARD:
1615                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1616                                 struct request_queue *rq = info->rq;
1617                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1618                                            info->gd->disk_name, op_name(bret->operation));
1619                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1620                                 info->feature_discard = 0;
1621                                 info->feature_secdiscard = 0;
1622                                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1623                                 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1624                         }
1625                         break;
1626                 case BLKIF_OP_FLUSH_DISKCACHE:
1627                 case BLKIF_OP_WRITE_BARRIER:
1628                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1629                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1630                                        info->gd->disk_name, op_name(bret->operation));
1631                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1632                         }
1633                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1634                                      rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1635                                 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1636                                        info->gd->disk_name, op_name(bret->operation));
1637                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1638                         }
1639                         if (unlikely(blkif_req(req)->error)) {
1640                                 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1641                                         blkif_req(req)->error = BLK_STS_OK;
1642                                 info->feature_fua = 0;
1643                                 info->feature_flush = 0;
1644                                 xlvbd_flush(info);
1645                         }
1646                         fallthrough;
1647                 case BLKIF_OP_READ:
1648                 case BLKIF_OP_WRITE:
1649                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
1650                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1651                                         "request: %x\n", bret->status);
1652
1653                         break;
1654                 default:
1655                         BUG();
1656                 }
1657
1658                 if (likely(!blk_should_fake_timeout(req->q)))
1659                         blk_mq_complete_request(req);
1660         }
1661
1662         rinfo->ring.rsp_cons = i;
1663
1664         if (i != rinfo->ring.req_prod_pvt) {
1665                 int more_to_do;
1666                 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1667                 if (more_to_do)
1668                         goto again;
1669         } else
1670                 rinfo->ring.sring->rsp_event = i + 1;
1671
1672         kick_pending_request_queues_locked(rinfo);
1673
1674         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1675
1676         return IRQ_HANDLED;
1677 }
1678
1679
1680 static int setup_blkring(struct xenbus_device *dev,
1681                          struct blkfront_ring_info *rinfo)
1682 {
1683         struct blkif_sring *sring;
1684         int err, i;
1685         struct blkfront_info *info = rinfo->dev_info;
1686         unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1687         grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1688
1689         for (i = 0; i < info->nr_ring_pages; i++)
1690                 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1691
1692         sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1693                                                        get_order(ring_size));
1694         if (!sring) {
1695                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1696                 return -ENOMEM;
1697         }
1698         SHARED_RING_INIT(sring);
1699         FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1700
1701         err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1702         if (err < 0) {
1703                 free_pages((unsigned long)sring, get_order(ring_size));
1704                 rinfo->ring.sring = NULL;
1705                 goto fail;
1706         }
1707         for (i = 0; i < info->nr_ring_pages; i++)
1708                 rinfo->ring_ref[i] = gref[i];
1709
1710         err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1711         if (err)
1712                 goto fail;
1713
1714         err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1715                                         "blkif", rinfo);
1716         if (err <= 0) {
1717                 xenbus_dev_fatal(dev, err,
1718                                  "bind_evtchn_to_irqhandler failed");
1719                 goto fail;
1720         }
1721         rinfo->irq = err;
1722
1723         return 0;
1724 fail:
1725         blkif_free(info, 0);
1726         return err;
1727 }
1728
1729 /*
1730  * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1731  * ring buffer may have multi pages depending on ->nr_ring_pages.
1732  */
1733 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1734                                 struct blkfront_ring_info *rinfo, const char *dir)
1735 {
1736         int err;
1737         unsigned int i;
1738         const char *message = NULL;
1739         struct blkfront_info *info = rinfo->dev_info;
1740
1741         if (info->nr_ring_pages == 1) {
1742                 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1743                 if (err) {
1744                         message = "writing ring-ref";
1745                         goto abort_transaction;
1746                 }
1747         } else {
1748                 for (i = 0; i < info->nr_ring_pages; i++) {
1749                         char ring_ref_name[RINGREF_NAME_LEN];
1750
1751                         snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1752                         err = xenbus_printf(xbt, dir, ring_ref_name,
1753                                             "%u", rinfo->ring_ref[i]);
1754                         if (err) {
1755                                 message = "writing ring-ref";
1756                                 goto abort_transaction;
1757                         }
1758                 }
1759         }
1760
1761         err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1762         if (err) {
1763                 message = "writing event-channel";
1764                 goto abort_transaction;
1765         }
1766
1767         return 0;
1768
1769 abort_transaction:
1770         xenbus_transaction_end(xbt, 1);
1771         if (message)
1772                 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1773
1774         return err;
1775 }
1776
1777 static void free_info(struct blkfront_info *info)
1778 {
1779         list_del(&info->info_list);
1780         kfree(info);
1781 }
1782
1783 /* Common code used when first setting up, and when resuming. */
1784 static int talk_to_blkback(struct xenbus_device *dev,
1785                            struct blkfront_info *info)
1786 {
1787         const char *message = NULL;
1788         struct xenbus_transaction xbt;
1789         int err;
1790         unsigned int i, max_page_order;
1791         unsigned int ring_page_order;
1792         struct blkfront_ring_info *rinfo;
1793
1794         if (!info)
1795                 return -ENODEV;
1796
1797         max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1798                                               "max-ring-page-order", 0);
1799         ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1800         info->nr_ring_pages = 1 << ring_page_order;
1801
1802         err = negotiate_mq(info);
1803         if (err)
1804                 goto destroy_blkring;
1805
1806         for_each_rinfo(info, rinfo, i) {
1807                 /* Create shared ring, alloc event channel. */
1808                 err = setup_blkring(dev, rinfo);
1809                 if (err)
1810                         goto destroy_blkring;
1811         }
1812
1813 again:
1814         err = xenbus_transaction_start(&xbt);
1815         if (err) {
1816                 xenbus_dev_fatal(dev, err, "starting transaction");
1817                 goto destroy_blkring;
1818         }
1819
1820         if (info->nr_ring_pages > 1) {
1821                 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1822                                     ring_page_order);
1823                 if (err) {
1824                         message = "writing ring-page-order";
1825                         goto abort_transaction;
1826                 }
1827         }
1828
1829         /* We already got the number of queues/rings in _probe */
1830         if (info->nr_rings == 1) {
1831                 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename);
1832                 if (err)
1833                         goto destroy_blkring;
1834         } else {
1835                 char *path;
1836                 size_t pathsize;
1837
1838                 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1839                                     info->nr_rings);
1840                 if (err) {
1841                         message = "writing multi-queue-num-queues";
1842                         goto abort_transaction;
1843                 }
1844
1845                 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1846                 path = kmalloc(pathsize, GFP_KERNEL);
1847                 if (!path) {
1848                         err = -ENOMEM;
1849                         message = "ENOMEM while writing ring references";
1850                         goto abort_transaction;
1851                 }
1852
1853                 for_each_rinfo(info, rinfo, i) {
1854                         memset(path, 0, pathsize);
1855                         snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1856                         err = write_per_ring_nodes(xbt, rinfo, path);
1857                         if (err) {
1858                                 kfree(path);
1859                                 goto destroy_blkring;
1860                         }
1861                 }
1862                 kfree(path);
1863         }
1864         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1865                             XEN_IO_PROTO_ABI_NATIVE);
1866         if (err) {
1867                 message = "writing protocol";
1868                 goto abort_transaction;
1869         }
1870         err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
1871                         info->feature_persistent);
1872         if (err)
1873                 dev_warn(&dev->dev,
1874                          "writing persistent grants feature to xenbus");
1875
1876         err = xenbus_transaction_end(xbt, 0);
1877         if (err) {
1878                 if (err == -EAGAIN)
1879                         goto again;
1880                 xenbus_dev_fatal(dev, err, "completing transaction");
1881                 goto destroy_blkring;
1882         }
1883
1884         for_each_rinfo(info, rinfo, i) {
1885                 unsigned int j;
1886
1887                 for (j = 0; j < BLK_RING_SIZE(info); j++)
1888                         rinfo->shadow[j].req.u.rw.id = j + 1;
1889                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1890         }
1891         xenbus_switch_state(dev, XenbusStateInitialised);
1892
1893         return 0;
1894
1895  abort_transaction:
1896         xenbus_transaction_end(xbt, 1);
1897         if (message)
1898                 xenbus_dev_fatal(dev, err, "%s", message);
1899  destroy_blkring:
1900         blkif_free(info, 0);
1901
1902         mutex_lock(&blkfront_mutex);
1903         free_info(info);
1904         mutex_unlock(&blkfront_mutex);
1905
1906         dev_set_drvdata(&dev->dev, NULL);
1907
1908         return err;
1909 }
1910
1911 static int negotiate_mq(struct blkfront_info *info)
1912 {
1913         unsigned int backend_max_queues;
1914         unsigned int i;
1915         struct blkfront_ring_info *rinfo;
1916
1917         BUG_ON(info->nr_rings);
1918
1919         /* Check if backend supports multiple queues. */
1920         backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1921                                                   "multi-queue-max-queues", 1);
1922         info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1923         /* We need at least one ring. */
1924         if (!info->nr_rings)
1925                 info->nr_rings = 1;
1926
1927         info->rinfo_size = struct_size(info->rinfo, shadow,
1928                                        BLK_RING_SIZE(info));
1929         info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL);
1930         if (!info->rinfo) {
1931                 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1932                 info->nr_rings = 0;
1933                 return -ENOMEM;
1934         }
1935
1936         for_each_rinfo(info, rinfo, i) {
1937                 INIT_LIST_HEAD(&rinfo->indirect_pages);
1938                 INIT_LIST_HEAD(&rinfo->grants);
1939                 rinfo->dev_info = info;
1940                 INIT_WORK(&rinfo->work, blkif_restart_queue);
1941                 spin_lock_init(&rinfo->ring_lock);
1942         }
1943         return 0;
1944 }
1945
1946 /* Enable the persistent grants feature. */
1947 static bool feature_persistent = true;
1948 module_param(feature_persistent, bool, 0644);
1949 MODULE_PARM_DESC(feature_persistent,
1950                 "Enables the persistent grants feature");
1951
1952 /**
1953  * Entry point to this code when a new device is created.  Allocate the basic
1954  * structures and the ring buffer for communication with the backend, and
1955  * inform the backend of the appropriate details for those.  Switch to
1956  * Initialised state.
1957  */
1958 static int blkfront_probe(struct xenbus_device *dev,
1959                           const struct xenbus_device_id *id)
1960 {
1961         int err, vdevice;
1962         struct blkfront_info *info;
1963
1964         /* FIXME: Use dynamic device id if this is not set. */
1965         err = xenbus_scanf(XBT_NIL, dev->nodename,
1966                            "virtual-device", "%i", &vdevice);
1967         if (err != 1) {
1968                 /* go looking in the extended area instead */
1969                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1970                                    "%i", &vdevice);
1971                 if (err != 1) {
1972                         xenbus_dev_fatal(dev, err, "reading virtual-device");
1973                         return err;
1974                 }
1975         }
1976
1977         if (xen_hvm_domain()) {
1978                 char *type;
1979                 int len;
1980                 /* no unplug has been done: do not hook devices != xen vbds */
1981                 if (xen_has_pv_and_legacy_disk_devices()) {
1982                         int major;
1983
1984                         if (!VDEV_IS_EXTENDED(vdevice))
1985                                 major = BLKIF_MAJOR(vdevice);
1986                         else
1987                                 major = XENVBD_MAJOR;
1988
1989                         if (major != XENVBD_MAJOR) {
1990                                 printk(KERN_INFO
1991                                                 "%s: HVM does not support vbd %d as xen block device\n",
1992                                                 __func__, vdevice);
1993                                 return -ENODEV;
1994                         }
1995                 }
1996                 /* do not create a PV cdrom device if we are an HVM guest */
1997                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1998                 if (IS_ERR(type))
1999                         return -ENODEV;
2000                 if (strncmp(type, "cdrom", 5) == 0) {
2001                         kfree(type);
2002                         return -ENODEV;
2003                 }
2004                 kfree(type);
2005         }
2006         info = kzalloc(sizeof(*info), GFP_KERNEL);
2007         if (!info) {
2008                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
2009                 return -ENOMEM;
2010         }
2011
2012         info->xbdev = dev;
2013
2014         mutex_init(&info->mutex);
2015         info->vdevice = vdevice;
2016         info->connected = BLKIF_STATE_DISCONNECTED;
2017
2018         info->feature_persistent = feature_persistent;
2019
2020         /* Front end dir is a number, which is used as the id. */
2021         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
2022         dev_set_drvdata(&dev->dev, info);
2023
2024         mutex_lock(&blkfront_mutex);
2025         list_add(&info->info_list, &info_list);
2026         mutex_unlock(&blkfront_mutex);
2027
2028         return 0;
2029 }
2030
2031 static int blkif_recover(struct blkfront_info *info)
2032 {
2033         unsigned int r_index;
2034         struct request *req, *n;
2035         int rc;
2036         struct bio *bio;
2037         unsigned int segs;
2038         struct blkfront_ring_info *rinfo;
2039
2040         blkfront_gather_backend_features(info);
2041         /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2042         blkif_set_queue_limits(info);
2043         segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2044         blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2045
2046         for_each_rinfo(info, rinfo, r_index) {
2047                 rc = blkfront_setup_indirect(rinfo);
2048                 if (rc)
2049                         return rc;
2050         }
2051         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2052
2053         /* Now safe for us to use the shared ring */
2054         info->connected = BLKIF_STATE_CONNECTED;
2055
2056         for_each_rinfo(info, rinfo, r_index) {
2057                 /* Kick any other new requests queued since we resumed */
2058                 kick_pending_request_queues(rinfo);
2059         }
2060
2061         list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2062                 /* Requeue pending requests (flush or discard) */
2063                 list_del_init(&req->queuelist);
2064                 BUG_ON(req->nr_phys_segments > segs);
2065                 blk_mq_requeue_request(req, false);
2066         }
2067         blk_mq_start_stopped_hw_queues(info->rq, true);
2068         blk_mq_kick_requeue_list(info->rq);
2069
2070         while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2071                 /* Traverse the list of pending bios and re-queue them */
2072                 submit_bio(bio);
2073         }
2074
2075         return 0;
2076 }
2077
2078 /**
2079  * We are reconnecting to the backend, due to a suspend/resume, or a backend
2080  * driver restart.  We tear down our blkif structure and recreate it, but
2081  * leave the device-layer structures intact so that this is transparent to the
2082  * rest of the kernel.
2083  */
2084 static int blkfront_resume(struct xenbus_device *dev)
2085 {
2086         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2087         int err = 0;
2088         unsigned int i, j;
2089         struct blkfront_ring_info *rinfo;
2090
2091         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2092
2093         bio_list_init(&info->bio_list);
2094         INIT_LIST_HEAD(&info->requests);
2095         for_each_rinfo(info, rinfo, i) {
2096                 struct bio_list merge_bio;
2097                 struct blk_shadow *shadow = rinfo->shadow;
2098
2099                 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2100                         /* Not in use? */
2101                         if (!shadow[j].request)
2102                                 continue;
2103
2104                         /*
2105                          * Get the bios in the request so we can re-queue them.
2106                          */
2107                         if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2108                             req_op(shadow[j].request) == REQ_OP_DISCARD ||
2109                             req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2110                             shadow[j].request->cmd_flags & REQ_FUA) {
2111                                 /*
2112                                  * Flush operations don't contain bios, so
2113                                  * we need to requeue the whole request
2114                                  *
2115                                  * XXX: but this doesn't make any sense for a
2116                                  * write with the FUA flag set..
2117                                  */
2118                                 list_add(&shadow[j].request->queuelist, &info->requests);
2119                                 continue;
2120                         }
2121                         merge_bio.head = shadow[j].request->bio;
2122                         merge_bio.tail = shadow[j].request->biotail;
2123                         bio_list_merge(&info->bio_list, &merge_bio);
2124                         shadow[j].request->bio = NULL;
2125                         blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2126                 }
2127         }
2128
2129         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2130
2131         err = talk_to_blkback(dev, info);
2132         if (!err)
2133                 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2134
2135         /*
2136          * We have to wait for the backend to switch to
2137          * connected state, since we want to read which
2138          * features it supports.
2139          */
2140
2141         return err;
2142 }
2143
2144 static void blkfront_closing(struct blkfront_info *info)
2145 {
2146         struct xenbus_device *xbdev = info->xbdev;
2147         struct block_device *bdev = NULL;
2148
2149         mutex_lock(&info->mutex);
2150
2151         if (xbdev->state == XenbusStateClosing) {
2152                 mutex_unlock(&info->mutex);
2153                 return;
2154         }
2155
2156         if (info->gd)
2157                 bdev = bdgrab(info->gd->part0);
2158
2159         mutex_unlock(&info->mutex);
2160
2161         if (!bdev) {
2162                 xenbus_frontend_closed(xbdev);
2163                 return;
2164         }
2165
2166         mutex_lock(&bdev->bd_mutex);
2167
2168         if (bdev->bd_openers) {
2169                 xenbus_dev_error(xbdev, -EBUSY,
2170                                  "Device in use; refusing to close");
2171                 xenbus_switch_state(xbdev, XenbusStateClosing);
2172         } else {
2173                 xlvbd_release_gendisk(info);
2174                 xenbus_frontend_closed(xbdev);
2175         }
2176
2177         mutex_unlock(&bdev->bd_mutex);
2178         bdput(bdev);
2179 }
2180
2181 static void blkfront_setup_discard(struct blkfront_info *info)
2182 {
2183         info->feature_discard = 1;
2184         info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
2185                                                          "discard-granularity",
2186                                                          0);
2187         info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
2188                                                        "discard-alignment", 0);
2189         info->feature_secdiscard =
2190                 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2191                                        0);
2192 }
2193
2194 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2195 {
2196         unsigned int psegs, grants, memflags;
2197         int err, i;
2198         struct blkfront_info *info = rinfo->dev_info;
2199
2200         memflags = memalloc_noio_save();
2201
2202         if (info->max_indirect_segments == 0) {
2203                 if (!HAS_EXTRA_REQ)
2204                         grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2205                 else {
2206                         /*
2207                          * When an extra req is required, the maximum
2208                          * grants supported is related to the size of the
2209                          * Linux block segment.
2210                          */
2211                         grants = GRANTS_PER_PSEG;
2212                 }
2213         }
2214         else
2215                 grants = info->max_indirect_segments;
2216         psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2217
2218         err = fill_grant_buffer(rinfo,
2219                                 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2220         if (err)
2221                 goto out_of_memory;
2222
2223         if (!info->feature_persistent && info->max_indirect_segments) {
2224                 /*
2225                  * We are using indirect descriptors but not persistent
2226                  * grants, we need to allocate a set of pages that can be
2227                  * used for mapping indirect grefs
2228                  */
2229                 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2230
2231                 BUG_ON(!list_empty(&rinfo->indirect_pages));
2232                 for (i = 0; i < num; i++) {
2233                         struct page *indirect_page = alloc_page(GFP_KERNEL);
2234                         if (!indirect_page)
2235                                 goto out_of_memory;
2236                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
2237                 }
2238         }
2239
2240         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2241                 rinfo->shadow[i].grants_used =
2242                         kvcalloc(grants,
2243                                  sizeof(rinfo->shadow[i].grants_used[0]),
2244                                  GFP_KERNEL);
2245                 rinfo->shadow[i].sg = kvcalloc(psegs,
2246                                                sizeof(rinfo->shadow[i].sg[0]),
2247                                                GFP_KERNEL);
2248                 if (info->max_indirect_segments)
2249                         rinfo->shadow[i].indirect_grants =
2250                                 kvcalloc(INDIRECT_GREFS(grants),
2251                                          sizeof(rinfo->shadow[i].indirect_grants[0]),
2252                                          GFP_KERNEL);
2253                 if ((rinfo->shadow[i].grants_used == NULL) ||
2254                         (rinfo->shadow[i].sg == NULL) ||
2255                      (info->max_indirect_segments &&
2256                      (rinfo->shadow[i].indirect_grants == NULL)))
2257                         goto out_of_memory;
2258                 sg_init_table(rinfo->shadow[i].sg, psegs);
2259         }
2260
2261         memalloc_noio_restore(memflags);
2262
2263         return 0;
2264
2265 out_of_memory:
2266         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2267                 kvfree(rinfo->shadow[i].grants_used);
2268                 rinfo->shadow[i].grants_used = NULL;
2269                 kvfree(rinfo->shadow[i].sg);
2270                 rinfo->shadow[i].sg = NULL;
2271                 kvfree(rinfo->shadow[i].indirect_grants);
2272                 rinfo->shadow[i].indirect_grants = NULL;
2273         }
2274         if (!list_empty(&rinfo->indirect_pages)) {
2275                 struct page *indirect_page, *n;
2276                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2277                         list_del(&indirect_page->lru);
2278                         __free_page(indirect_page);
2279                 }
2280         }
2281
2282         memalloc_noio_restore(memflags);
2283
2284         return -ENOMEM;
2285 }
2286
2287 /*
2288  * Gather all backend feature-*
2289  */
2290 static void blkfront_gather_backend_features(struct blkfront_info *info)
2291 {
2292         unsigned int indirect_segments;
2293
2294         info->feature_flush = 0;
2295         info->feature_fua = 0;
2296
2297         /*
2298          * If there's no "feature-barrier" defined, then it means
2299          * we're dealing with a very old backend which writes
2300          * synchronously; nothing to do.
2301          *
2302          * If there are barriers, then we use flush.
2303          */
2304         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2305                 info->feature_flush = 1;
2306                 info->feature_fua = 1;
2307         }
2308
2309         /*
2310          * And if there is "feature-flush-cache" use that above
2311          * barriers.
2312          */
2313         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2314                                  0)) {
2315                 info->feature_flush = 1;
2316                 info->feature_fua = 0;
2317         }
2318
2319         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2320                 blkfront_setup_discard(info);
2321
2322         if (info->feature_persistent)
2323                 info->feature_persistent =
2324                         !!xenbus_read_unsigned(info->xbdev->otherend,
2325                                                "feature-persistent", 0);
2326
2327         indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2328                                         "feature-max-indirect-segments", 0);
2329         if (indirect_segments > xen_blkif_max_segments)
2330                 indirect_segments = xen_blkif_max_segments;
2331         if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2332                 indirect_segments = 0;
2333         info->max_indirect_segments = indirect_segments;
2334
2335         if (info->feature_persistent) {
2336                 mutex_lock(&blkfront_mutex);
2337                 schedule_delayed_work(&blkfront_work, HZ * 10);
2338                 mutex_unlock(&blkfront_mutex);
2339         }
2340 }
2341
2342 /*
2343  * Invoked when the backend is finally 'ready' (and has told produced
2344  * the details about the physical device - #sectors, size, etc).
2345  */
2346 static void blkfront_connect(struct blkfront_info *info)
2347 {
2348         unsigned long long sectors;
2349         unsigned long sector_size;
2350         unsigned int physical_sector_size;
2351         unsigned int binfo;
2352         int err, i;
2353         struct blkfront_ring_info *rinfo;
2354
2355         switch (info->connected) {
2356         case BLKIF_STATE_CONNECTED:
2357                 /*
2358                  * Potentially, the back-end may be signalling
2359                  * a capacity change; update the capacity.
2360                  */
2361                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2362                                    "sectors", "%Lu", &sectors);
2363                 if (XENBUS_EXIST_ERR(err))
2364                         return;
2365                 printk(KERN_INFO "Setting capacity to %Lu\n",
2366                        sectors);
2367                 set_capacity_and_notify(info->gd, sectors);
2368
2369                 return;
2370         case BLKIF_STATE_SUSPENDED:
2371                 /*
2372                  * If we are recovering from suspension, we need to wait
2373                  * for the backend to announce it's features before
2374                  * reconnecting, at least we need to know if the backend
2375                  * supports indirect descriptors, and how many.
2376                  */
2377                 blkif_recover(info);
2378                 return;
2379
2380         default:
2381                 break;
2382         }
2383
2384         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2385                 __func__, info->xbdev->otherend);
2386
2387         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2388                             "sectors", "%llu", &sectors,
2389                             "info", "%u", &binfo,
2390                             "sector-size", "%lu", &sector_size,
2391                             NULL);
2392         if (err) {
2393                 xenbus_dev_fatal(info->xbdev, err,
2394                                  "reading backend fields at %s",
2395                                  info->xbdev->otherend);
2396                 return;
2397         }
2398
2399         /*
2400          * physcial-sector-size is a newer field, so old backends may not
2401          * provide this. Assume physical sector size to be the same as
2402          * sector_size in that case.
2403          */
2404         physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2405                                                     "physical-sector-size",
2406                                                     sector_size);
2407         blkfront_gather_backend_features(info);
2408         for_each_rinfo(info, rinfo, i) {
2409                 err = blkfront_setup_indirect(rinfo);
2410                 if (err) {
2411                         xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2412                                          info->xbdev->otherend);
2413                         blkif_free(info, 0);
2414                         break;
2415                 }
2416         }
2417
2418         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2419                                   physical_sector_size);
2420         if (err) {
2421                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2422                                  info->xbdev->otherend);
2423                 goto fail;
2424         }
2425
2426         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2427
2428         /* Kick pending requests. */
2429         info->connected = BLKIF_STATE_CONNECTED;
2430         for_each_rinfo(info, rinfo, i)
2431                 kick_pending_request_queues(rinfo);
2432
2433         device_add_disk(&info->xbdev->dev, info->gd, NULL);
2434
2435         info->is_ready = 1;
2436         return;
2437
2438 fail:
2439         blkif_free(info, 0);
2440         return;
2441 }
2442
2443 /**
2444  * Callback received when the backend's state changes.
2445  */
2446 static void blkback_changed(struct xenbus_device *dev,
2447                             enum xenbus_state backend_state)
2448 {
2449         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2450
2451         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2452
2453         switch (backend_state) {
2454         case XenbusStateInitWait:
2455                 if (dev->state != XenbusStateInitialising)
2456                         break;
2457                 if (talk_to_blkback(dev, info))
2458                         break;
2459                 break;
2460         case XenbusStateInitialising:
2461         case XenbusStateInitialised:
2462         case XenbusStateReconfiguring:
2463         case XenbusStateReconfigured:
2464         case XenbusStateUnknown:
2465                 break;
2466
2467         case XenbusStateConnected:
2468                 /*
2469                  * talk_to_blkback sets state to XenbusStateInitialised
2470                  * and blkfront_connect sets it to XenbusStateConnected
2471                  * (if connection went OK).
2472                  *
2473                  * If the backend (or toolstack) decides to poke at backend
2474                  * state (and re-trigger the watch by setting the state repeatedly
2475                  * to XenbusStateConnected (4)) we need to deal with this.
2476                  * This is allowed as this is used to communicate to the guest
2477                  * that the size of disk has changed!
2478                  */
2479                 if ((dev->state != XenbusStateInitialised) &&
2480                     (dev->state != XenbusStateConnected)) {
2481                         if (talk_to_blkback(dev, info))
2482                                 break;
2483                 }
2484
2485                 blkfront_connect(info);
2486                 break;
2487
2488         case XenbusStateClosed:
2489                 if (dev->state == XenbusStateClosed)
2490                         break;
2491                 fallthrough;
2492         case XenbusStateClosing:
2493                 if (info)
2494                         blkfront_closing(info);
2495                 break;
2496         }
2497 }
2498
2499 static int blkfront_remove(struct xenbus_device *xbdev)
2500 {
2501         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2502         struct block_device *bdev = NULL;
2503         struct gendisk *disk;
2504
2505         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2506
2507         if (!info)
2508                 return 0;
2509
2510         blkif_free(info, 0);
2511
2512         mutex_lock(&info->mutex);
2513
2514         disk = info->gd;
2515         if (disk)
2516                 bdev = bdgrab(disk->part0);
2517
2518         info->xbdev = NULL;
2519         mutex_unlock(&info->mutex);
2520
2521         if (!bdev) {
2522                 mutex_lock(&blkfront_mutex);
2523                 free_info(info);
2524                 mutex_unlock(&blkfront_mutex);
2525                 return 0;
2526         }
2527
2528         /*
2529          * The xbdev was removed before we reached the Closed
2530          * state. See if it's safe to remove the disk. If the bdev
2531          * isn't closed yet, we let release take care of it.
2532          */
2533
2534         mutex_lock(&bdev->bd_mutex);
2535         info = disk->private_data;
2536
2537         dev_warn(disk_to_dev(disk),
2538                  "%s was hot-unplugged, %d stale handles\n",
2539                  xbdev->nodename, bdev->bd_openers);
2540
2541         if (info && !bdev->bd_openers) {
2542                 xlvbd_release_gendisk(info);
2543                 disk->private_data = NULL;
2544                 mutex_lock(&blkfront_mutex);
2545                 free_info(info);
2546                 mutex_unlock(&blkfront_mutex);
2547         }
2548
2549         mutex_unlock(&bdev->bd_mutex);
2550         bdput(bdev);
2551
2552         return 0;
2553 }
2554
2555 static int blkfront_is_ready(struct xenbus_device *dev)
2556 {
2557         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2558
2559         return info->is_ready && info->xbdev;
2560 }
2561
2562 static int blkif_open(struct block_device *bdev, fmode_t mode)
2563 {
2564         struct gendisk *disk = bdev->bd_disk;
2565         struct blkfront_info *info;
2566         int err = 0;
2567
2568         mutex_lock(&blkfront_mutex);
2569
2570         info = disk->private_data;
2571         if (!info) {
2572                 /* xbdev gone */
2573                 err = -ERESTARTSYS;
2574                 goto out;
2575         }
2576
2577         mutex_lock(&info->mutex);
2578
2579         if (!info->gd)
2580                 /* xbdev is closed */
2581                 err = -ERESTARTSYS;
2582
2583         mutex_unlock(&info->mutex);
2584
2585 out:
2586         mutex_unlock(&blkfront_mutex);
2587         return err;
2588 }
2589
2590 static void blkif_release(struct gendisk *disk, fmode_t mode)
2591 {
2592         struct blkfront_info *info = disk->private_data;
2593         struct xenbus_device *xbdev;
2594
2595         mutex_lock(&blkfront_mutex);
2596         if (disk->part0->bd_openers)
2597                 goto out_mutex;
2598
2599         /*
2600          * Check if we have been instructed to close. We will have
2601          * deferred this request, because the bdev was still open.
2602          */
2603
2604         mutex_lock(&info->mutex);
2605         xbdev = info->xbdev;
2606
2607         if (xbdev && xbdev->state == XenbusStateClosing) {
2608                 /* pending switch to state closed */
2609                 dev_info(disk_to_dev(disk), "releasing disk\n");
2610                 xlvbd_release_gendisk(info);
2611                 xenbus_frontend_closed(info->xbdev);
2612         }
2613
2614         mutex_unlock(&info->mutex);
2615
2616         if (!xbdev) {
2617                 /* sudden device removal */
2618                 dev_info(disk_to_dev(disk), "releasing disk\n");
2619                 xlvbd_release_gendisk(info);
2620                 disk->private_data = NULL;
2621                 free_info(info);
2622         }
2623
2624 out_mutex:
2625         mutex_unlock(&blkfront_mutex);
2626 }
2627
2628 static const struct block_device_operations xlvbd_block_fops =
2629 {
2630         .owner = THIS_MODULE,
2631         .open = blkif_open,
2632         .release = blkif_release,
2633         .getgeo = blkif_getgeo,
2634         .ioctl = blkif_ioctl,
2635         .compat_ioctl = blkdev_compat_ptr_ioctl,
2636 };
2637
2638
2639 static const struct xenbus_device_id blkfront_ids[] = {
2640         { "vbd" },
2641         { "" }
2642 };
2643
2644 static struct xenbus_driver blkfront_driver = {
2645         .ids  = blkfront_ids,
2646         .probe = blkfront_probe,
2647         .remove = blkfront_remove,
2648         .resume = blkfront_resume,
2649         .otherend_changed = blkback_changed,
2650         .is_ready = blkfront_is_ready,
2651 };
2652
2653 static void purge_persistent_grants(struct blkfront_info *info)
2654 {
2655         unsigned int i;
2656         unsigned long flags;
2657         struct blkfront_ring_info *rinfo;
2658
2659         for_each_rinfo(info, rinfo, i) {
2660                 struct grant *gnt_list_entry, *tmp;
2661
2662                 spin_lock_irqsave(&rinfo->ring_lock, flags);
2663
2664                 if (rinfo->persistent_gnts_c == 0) {
2665                         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2666                         continue;
2667                 }
2668
2669                 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2670                                          node) {
2671                         if (gnt_list_entry->gref == GRANT_INVALID_REF ||
2672                             gnttab_query_foreign_access(gnt_list_entry->gref))
2673                                 continue;
2674
2675                         list_del(&gnt_list_entry->node);
2676                         gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL);
2677                         rinfo->persistent_gnts_c--;
2678                         gnt_list_entry->gref = GRANT_INVALID_REF;
2679                         list_add_tail(&gnt_list_entry->node, &rinfo->grants);
2680                 }
2681
2682                 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2683         }
2684 }
2685
2686 static void blkfront_delay_work(struct work_struct *work)
2687 {
2688         struct blkfront_info *info;
2689         bool need_schedule_work = false;
2690
2691         mutex_lock(&blkfront_mutex);
2692
2693         list_for_each_entry(info, &info_list, info_list) {
2694                 if (info->feature_persistent) {
2695                         need_schedule_work = true;
2696                         mutex_lock(&info->mutex);
2697                         purge_persistent_grants(info);
2698                         mutex_unlock(&info->mutex);
2699                 }
2700         }
2701
2702         if (need_schedule_work)
2703                 schedule_delayed_work(&blkfront_work, HZ * 10);
2704
2705         mutex_unlock(&blkfront_mutex);
2706 }
2707
2708 static int __init xlblk_init(void)
2709 {
2710         int ret;
2711         int nr_cpus = num_online_cpus();
2712
2713         if (!xen_domain())
2714                 return -ENODEV;
2715
2716         if (!xen_has_pv_disk_devices())
2717                 return -ENODEV;
2718
2719         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2720                 pr_warn("xen_blk: can't get major %d with name %s\n",
2721                         XENVBD_MAJOR, DEV_NAME);
2722                 return -ENODEV;
2723         }
2724
2725         if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2726                 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2727
2728         if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2729                 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2730                         xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2731                 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2732         }
2733
2734         if (xen_blkif_max_queues > nr_cpus) {
2735                 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2736                         xen_blkif_max_queues, nr_cpus);
2737                 xen_blkif_max_queues = nr_cpus;
2738         }
2739
2740         INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2741
2742         ret = xenbus_register_frontend(&blkfront_driver);
2743         if (ret) {
2744                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2745                 return ret;
2746         }
2747
2748         return 0;
2749 }
2750 module_init(xlblk_init);
2751
2752
2753 static void __exit xlblk_exit(void)
2754 {
2755         cancel_delayed_work_sync(&blkfront_work);
2756
2757         xenbus_unregister_driver(&blkfront_driver);
2758         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2759         kfree(minors);
2760 }
2761 module_exit(xlblk_exit);
2762
2763 MODULE_DESCRIPTION("Xen virtual block device frontend");
2764 MODULE_LICENSE("GPL");
2765 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2766 MODULE_ALIAS("xen:vbd");
2767 MODULE_ALIAS("xenblk");