drivers/block/xen-blkfront.c

   1 /*
   2  * blkfront.c
   3  *
   4  * XenLinux virtual block device driver.
   5  *
   6  * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
   7  * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
   8  * Copyright (c) 2004, Christian Limpach
   9  * Copyright (c) 2004, Andrew Warfield
  10  * Copyright (c) 2005, Christopher Clark
  11  * Copyright (c) 2005, XenSource Ltd
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License version 2
  15  * as published by the Free Software Foundation; or, when distributed
  16  * separately from the Linux kernel or incorporated into other
  17  * software packages, subject to the following license:
  18  *
  19  * Permission is hereby granted, free of charge, to any person obtaining a copy
  20  * of this source file (the "Software"), to deal in the Software without
  21  * restriction, including without limitation the rights to use, copy, modify,
  22  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  23  * and to permit persons to whom the Software is furnished to do so, subject to
  24  * the following conditions:
  25  *
  26  * The above copyright notice and this permission notice shall be included in
  27  * all copies or substantial portions of the Software.
  28  *
  29  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  30  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  31  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  32  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  33  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  34  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  35  * IN THE SOFTWARE.
  36  */
  37
  38 #include <linux/interrupt.h>
  39 #include <linux/blkdev.h>
  40 #include <linux/blk-mq.h>
  41 #include <linux/hdreg.h>
  42 #include <linux/cdrom.h>
  43 #include <linux/module.h>
  44 #include <linux/slab.h>
  45 #include <linux/mutex.h>
  46 #include <linux/scatterlist.h>
  47 #include <linux/bitmap.h>
  48 #include <linux/list.h>
  49
  50 #include <xen/xen.h>
  51 #include <xen/xenbus.h>
  52 #include <xen/grant_table.h>
  53 #include <xen/events.h>
  54 #include <xen/page.h>
  55 #include <xen/platform_pci.h>
  56
  57 #include <xen/interface/grant_table.h>
  58 #include <xen/interface/io/blkif.h>
  59 #include <xen/interface/io/protocols.h>
  60
  61 #include <asm/xen/hypervisor.h>
  62
  63 /*
  64  * The minimal size of segment supported by the block framework is PAGE_SIZE.
  65  * When Linux is using a different page size than Xen, it may not be possible
  66  * to put all the data in a single segment.
  67  * This can happen when the backend doesn't support indirect descriptor and
  68  * therefore the maximum amount of data that a request can carry is
  69  * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
  70  *
  71  * Note that we only support one extra request. So the Linux page size
  72  * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
  73  * 88KB.
  74  */
  75 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
  76
  77 enum blkif_state {
  78         BLKIF_STATE_DISCONNECTED,
  79         BLKIF_STATE_CONNECTED,
  80         BLKIF_STATE_SUSPENDED,
  81 };
  82
  83 struct grant {
  84         grant_ref_t gref;
  85         struct page *page;
  86         struct list_head node;
  87 };
  88
  89 enum blk_req_status {
  90         REQ_WAITING,
  91         REQ_DONE,
  92         REQ_ERROR,
  93         REQ_EOPNOTSUPP,
  94 };
  95
  96 struct blk_shadow {
  97         struct blkif_request req;
  98         struct request *request;
  99         struct grant **grants_used;
 100         struct grant **indirect_grants;
 101         struct scatterlist *sg;
 102         unsigned int num_sg;
 103         enum blk_req_status status;
 104
 105         #define NO_ASSOCIATED_ID ~0UL
 106         /*
 107          * Id of the sibling if we ever need 2 requests when handling a
 108          * block I/O request
 109          */
 110         unsigned long associated_id;
 111 };
 112
 113 struct blkif_req {
 114         int     error;
 115 };
 116
 117 static inline struct blkif_req *blkif_req(struct request *rq)
 118 {
 119         return blk_mq_rq_to_pdu(rq);
 120 }
 121
 122 static DEFINE_MUTEX(blkfront_mutex);
 123 static const struct block_device_operations xlvbd_block_fops;
 124
 125 /*
 126  * Maximum number of segments in indirect requests, the actual value used by
 127  * the frontend driver is the minimum of this value and the value provided
 128  * by the backend driver.
 129  */
 130
 131 static unsigned int xen_blkif_max_segments = 32;
 132 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint,
 133                    S_IRUGO);
 134 MODULE_PARM_DESC(max_indirect_segments,
 135                  "Maximum amount of segments in indirect requests (default is 32)");
 136
 137 static unsigned int xen_blkif_max_queues = 4;
 138 module_param_named(max_queues, xen_blkif_max_queues, uint, S_IRUGO);
 139 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
 140
 141 /*
 142  * Maximum order of pages to be used for the shared ring between front and
 143  * backend, 4KB page granularity is used.
 144  */
 145 static unsigned int xen_blkif_max_ring_order;
 146 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, S_IRUGO);
 147 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
 148
 149 #define BLK_RING_SIZE(info)     \
 150         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
 151
 152 #define BLK_MAX_RING_SIZE       \
 153         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS)
 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 blk_shadow shadow[BLK_MAX_RING_SIZE];
 179         struct list_head indirect_pages;
 180         struct list_head grants;
 181         unsigned int persistent_gnts_c;
 182         unsigned long shadow_free;
 183         struct blkfront_info *dev_info;
 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         /* Save uncomplete reqs and bios for migration. */
 218         struct list_head requests;
 219         struct bio_list bio_list;
 220 };
 221
 222 static unsigned int nr_minors;
 223 static unsigned long *minors;
 224 static DEFINE_SPINLOCK(minor_lock);
 225
 226 #define GRANT_INVALID_REF       0
 227
 228 #define PARTS_PER_DISK          16
 229 #define PARTS_PER_EXT_DISK      256
 230
 231 #define BLKIF_MAJOR(dev) ((dev)>>8)
 232 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 233
 234 #define EXT_SHIFT 28
 235 #define EXTENDED (1<<EXT_SHIFT)
 236 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 237 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 238 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 239 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 240 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 241 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 242
 243 #define DEV_NAME        "xvd"   /* name in /dev */
 244
 245 /*
 246  * Grants are always the same size as a Xen page (i.e 4KB).
 247  * A physical segment is always the same size as a Linux page.
 248  * Number of grants per physical segment
 249  */
 250 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
 251
 252 #define GRANTS_PER_INDIRECT_FRAME \
 253         (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
 254
 255 #define PSEGS_PER_INDIRECT_FRAME        \
 256         (GRANTS_INDIRECT_FRAME / GRANTS_PSEGS)
 257
 258 #define INDIRECT_GREFS(_grants)         \
 259         DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
 260
 261 #define GREFS(_psegs)   ((_psegs) * GRANTS_PER_PSEG)
 262
 263 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 264 static void blkfront_gather_backend_features(struct blkfront_info *info);
 265
 266 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 267 {
 268         unsigned long free = rinfo->shadow_free;
 269
 270         BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
 271         rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
 272         rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 273         return free;
 274 }
 275
 276 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
 277                               unsigned long id)
 278 {
 279         if (rinfo->shadow[id].req.u.rw.id != id)
 280                 return -EINVAL;
 281         if (rinfo->shadow[id].request == NULL)
 282                 return -EINVAL;
 283         rinfo->shadow[id].req.u.rw.id  = rinfo->shadow_free;
 284         rinfo->shadow[id].request = NULL;
 285         rinfo->shadow_free = id;
 286         return 0;
 287 }
 288
 289 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 290 {
 291         struct blkfront_info *info = rinfo->dev_info;
 292         struct page *granted_page;
 293         struct grant *gnt_list_entry, *n;
 294         int i = 0;
 295
 296         while (i < num) {
 297                 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
 298                 if (!gnt_list_entry)
 299                         goto out_of_memory;
 300
 301                 if (info->feature_persistent) {
 302                         granted_page = alloc_page(GFP_NOIO);
 303                         if (!granted_page) {
 304                                 kfree(gnt_list_entry);
 305                                 goto out_of_memory;
 306                         }
 307                         gnt_list_entry->page = granted_page;
 308                 }
 309
 310                 gnt_list_entry->gref = GRANT_INVALID_REF;
 311                 list_add(&gnt_list_entry->node, &rinfo->grants);
 312                 i++;
 313         }
 314
 315         return 0;
 316
 317 out_of_memory:
 318         list_for_each_entry_safe(gnt_list_entry, n,
 319                                  &rinfo->grants, node) {
 320                 list_del(&gnt_list_entry->node);
 321                 if (info->feature_persistent)
 322                         __free_page(gnt_list_entry->page);
 323                 kfree(gnt_list_entry);
 324                 i--;
 325         }
 326         BUG_ON(i != 0);
 327         return -ENOMEM;
 328 }
 329
 330 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
 331 {
 332         struct grant *gnt_list_entry;
 333
 334         BUG_ON(list_empty(&rinfo->grants));
 335         gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
 336                                           node);
 337         list_del(&gnt_list_entry->node);
 338
 339         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 340                 rinfo->persistent_gnts_c--;
 341
 342         return gnt_list_entry;
 343 }
 344
 345 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
 346                                         const struct blkfront_info *info)
 347 {
 348         gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
 349                                                  info->xbdev->otherend_id,
 350                                                  gnt_list_entry->page,
 351                                                  0);
 352 }
 353
 354 static struct grant *get_grant(grant_ref_t *gref_head,
 355                                unsigned long gfn,
 356                                struct blkfront_ring_info *rinfo)
 357 {
 358         struct grant *gnt_list_entry = get_free_grant(rinfo);
 359         struct blkfront_info *info = rinfo->dev_info;
 360
 361         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 362                 return gnt_list_entry;
 363
 364         /* Assign a gref to this page */
 365         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 366         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 367         if (info->feature_persistent)
 368                 grant_foreign_access(gnt_list_entry, info);
 369         else {
 370                 /* Grant access to the GFN passed by the caller */
 371                 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
 372                                                 info->xbdev->otherend_id,
 373                                                 gfn, 0);
 374         }
 375
 376         return gnt_list_entry;
 377 }
 378
 379 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
 380                                         struct blkfront_ring_info *rinfo)
 381 {
 382         struct grant *gnt_list_entry = get_free_grant(rinfo);
 383         struct blkfront_info *info = rinfo->dev_info;
 384
 385         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 386                 return gnt_list_entry;
 387
 388         /* Assign a gref to this page */
 389         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 390         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 391         if (!info->feature_persistent) {
 392                 struct page *indirect_page;
 393
 394                 /* Fetch a pre-allocated page to use for indirect grefs */
 395                 BUG_ON(list_empty(&rinfo->indirect_pages));
 396                 indirect_page = list_first_entry(&rinfo->indirect_pages,
 397                                                  struct page, lru);
 398                 list_del(&indirect_page->lru);
 399                 gnt_list_entry->page = indirect_page;
 400         }
 401         grant_foreign_access(gnt_list_entry, info);
 402
 403         return gnt_list_entry;
 404 }
 405
 406 static const char *op_name(int op)
 407 {
 408         static const char *const names[] = {
 409                 [BLKIF_OP_READ] = "read",
 410                 [BLKIF_OP_WRITE] = "write",
 411                 [BLKIF_OP_WRITE_BARRIER] = "barrier",
 412                 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
 413                 [BLKIF_OP_DISCARD] = "discard" };
 414
 415         if (op < 0 || op >= ARRAY_SIZE(names))
 416                 return "unknown";
 417
 418         if (!names[op])
 419                 return "reserved";
 420
 421         return names[op];
 422 }
 423 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 424 {
 425         unsigned int end = minor + nr;
 426         int rc;
 427
 428         if (end > nr_minors) {
 429                 unsigned long *bitmap, *old;
 430
 431                 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 432                                  GFP_KERNEL);
 433                 if (bitmap == NULL)
 434                         return -ENOMEM;
 435
 436                 spin_lock(&minor_lock);
 437                 if (end > nr_minors) {
 438                         old = minors;
 439                         memcpy(bitmap, minors,
 440                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 441                         minors = bitmap;
 442                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 443                 } else
 444                         old = bitmap;
 445                 spin_unlock(&minor_lock);
 446                 kfree(old);
 447         }
 448
 449         spin_lock(&minor_lock);
 450         if (find_next_bit(minors, end, minor) >= end) {
 451                 bitmap_set(minors, minor, nr);
 452                 rc = 0;
 453         } else
 454                 rc = -EBUSY;
 455         spin_unlock(&minor_lock);
 456
 457         return rc;
 458 }
 459
 460 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 461 {
 462         unsigned int end = minor + nr;
 463
 464         BUG_ON(end > nr_minors);
 465         spin_lock(&minor_lock);
 466         bitmap_clear(minors,  minor, nr);
 467         spin_unlock(&minor_lock);
 468 }
 469
 470 static void blkif_restart_queue_callback(void *arg)
 471 {
 472         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
 473         schedule_work(&rinfo->work);
 474 }
 475
 476 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 477 {
 478         /* We don't have real geometry info, but let's at least return
 479            values consistent with the size of the device */
 480         sector_t nsect = get_capacity(bd->bd_disk);
 481         sector_t cylinders = nsect;
 482
 483         hg->heads = 0xff;
 484         hg->sectors = 0x3f;
 485         sector_div(cylinders, hg->heads * hg->sectors);
 486         hg->cylinders = cylinders;
 487         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 488                 hg->cylinders = 0xffff;
 489         return 0;
 490 }
 491
 492 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 493                        unsigned command, unsigned long argument)
 494 {
 495         struct blkfront_info *info = bdev->bd_disk->private_data;
 496         int i;
 497
 498         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 499                 command, (long)argument);
 500
 501         switch (command) {
 502         case CDROMMULTISESSION:
 503                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 504                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 505                         if (put_user(0, (char __user *)(argument + i)))
 506                                 return -EFAULT;
 507                 return 0;
 508
 509         case CDROM_GET_CAPABILITY: {
 510                 struct gendisk *gd = info->gd;
 511                 if (gd->flags & GENHD_FL_CD)
 512                         return 0;
 513                 return -EINVAL;
 514         }
 515
 516         default:
 517                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 518                   command);*/
 519                 return -EINVAL; /* same return as native Linux */
 520         }
 521
 522         return 0;
 523 }
 524
 525 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 526                                             struct request *req,
 527                                             struct blkif_request **ring_req)
 528 {
 529         unsigned long id;
 530
 531         *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
 532         rinfo->ring.req_prod_pvt++;
 533
 534         id = get_id_from_freelist(rinfo);
 535         rinfo->shadow[id].request = req;
 536         rinfo->shadow[id].status = REQ_WAITING;
 537         rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
 538
 539         (*ring_req)->u.rw.id = id;
 540
 541         return id;
 542 }
 543
 544 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
 545 {
 546         struct blkfront_info *info = rinfo->dev_info;
 547         struct blkif_request *ring_req;
 548         unsigned long id;
 549
 550         /* Fill out a communications ring structure. */
 551         id = blkif_ring_get_request(rinfo, req, &ring_req);
 552
 553         ring_req->operation = BLKIF_OP_DISCARD;
 554         ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
 555         ring_req->u.discard.id = id;
 556         ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
 557         if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
 558                 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
 559         else
 560                 ring_req->u.discard.flag = 0;
 561
 562         /* Keep a private copy so we can reissue requests when recovering. */
 563         rinfo->shadow[id].req = *ring_req;
 564
 565         return 0;
 566 }
 567
 568 struct setup_rw_req {
 569         unsigned int grant_idx;
 570         struct blkif_request_segment *segments;
 571         struct blkfront_ring_info *rinfo;
 572         struct blkif_request *ring_req;
 573         grant_ref_t gref_head;
 574         unsigned int id;
 575         /* Only used when persistent grant is used and it's a read request */
 576         bool need_copy;
 577         unsigned int bvec_off;
 578         char *bvec_data;
 579
 580         bool require_extra_req;
 581         struct blkif_request *extra_ring_req;
 582 };
 583
 584 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
 585                                      unsigned int len, void *data)
 586 {
 587         struct setup_rw_req *setup = data;
 588         int n, ref;
 589         struct grant *gnt_list_entry;
 590         unsigned int fsect, lsect;
 591         /* Convenient aliases */
 592         unsigned int grant_idx = setup->grant_idx;
 593         struct blkif_request *ring_req = setup->ring_req;
 594         struct blkfront_ring_info *rinfo = setup->rinfo;
 595         /*
 596          * We always use the shadow of the first request to store the list
 597          * of grant associated to the block I/O request. This made the
 598          * completion more easy to handle even if the block I/O request is
 599          * split.
 600          */
 601         struct blk_shadow *shadow = &rinfo->shadow[setup->id];
 602
 603         if (unlikely(setup->require_extra_req &&
 604                      grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
 605                 /*
 606                  * We are using the second request, setup grant_idx
 607                  * to be the index of the segment array.
 608                  */
 609                 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
 610                 ring_req = setup->extra_ring_req;
 611         }
 612
 613         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 614             (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
 615                 if (setup->segments)
 616                         kunmap_atomic(setup->segments);
 617
 618                 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
 619                 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
 620                 shadow->indirect_grants[n] = gnt_list_entry;
 621                 setup->segments = kmap_atomic(gnt_list_entry->page);
 622                 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 623         }
 624
 625         gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
 626         ref = gnt_list_entry->gref;
 627         /*
 628          * All the grants are stored in the shadow of the first
 629          * request. Therefore we have to use the global index.
 630          */
 631         shadow->grants_used[setup->grant_idx] = gnt_list_entry;
 632
 633         if (setup->need_copy) {
 634                 void *shared_data;
 635
 636                 shared_data = kmap_atomic(gnt_list_entry->page);
 637                 /*
 638                  * this does not wipe data stored outside the
 639                  * range sg->offset..sg->offset+sg->length.
 640                  * Therefore, blkback *could* see data from
 641                  * previous requests. This is OK as long as
 642                  * persistent grants are shared with just one
 643                  * domain. It may need refactoring if this
 644                  * changes
 645                  */
 646                 memcpy(shared_data + offset,
 647                        setup->bvec_data + setup->bvec_off,
 648                        len);
 649
 650                 kunmap_atomic(shared_data);
 651                 setup->bvec_off += len;
 652         }
 653
 654         fsect = offset >> 9;
 655         lsect = fsect + (len >> 9) - 1;
 656         if (ring_req->operation != BLKIF_OP_INDIRECT) {
 657                 ring_req->u.rw.seg[grant_idx] =
 658                         (struct blkif_request_segment) {
 659                                 .gref       = ref,
 660                                 .first_sect = fsect,
 661                                 .last_sect  = lsect };
 662         } else {
 663                 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
 664                         (struct blkif_request_segment) {
 665                                 .gref       = ref,
 666                                 .first_sect = fsect,
 667                                 .last_sect  = lsect };
 668         }
 669
 670         (setup->grant_idx)++;
 671 }
 672
 673 static void blkif_setup_extra_req(struct blkif_request *first,
 674                                   struct blkif_request *second)
 675 {
 676         uint16_t nr_segments = first->u.rw.nr_segments;
 677
 678         /*
 679          * The second request is only present when the first request uses
 680          * all its segments. It's always the continuity of the first one.
 681          */
 682         first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 683
 684         second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
 685         second->u.rw.sector_number = first->u.rw.sector_number +
 686                 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
 687
 688         second->u.rw.handle = first->u.rw.handle;
 689         second->operation = first->operation;
 690 }
 691
 692 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
 693 {
 694         struct blkfront_info *info = rinfo->dev_info;
 695         struct blkif_request *ring_req, *extra_ring_req = NULL;
 696         unsigned long id, extra_id = NO_ASSOCIATED_ID;
 697         bool require_extra_req = false;
 698         int i;
 699         struct setup_rw_req setup = {
 700                 .grant_idx = 0,
 701                 .segments = NULL,
 702                 .rinfo = rinfo,
 703                 .need_copy = rq_data_dir(req) && info->feature_persistent,
 704         };
 705
 706         /*
 707          * Used to store if we are able to queue the request by just using
 708          * existing persistent grants, or if we have to get new grants,
 709          * as there are not sufficiently many free.
 710          */
 711         struct scatterlist *sg;
 712         int num_sg, max_grefs, num_grant;
 713
 714         max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
 715         if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
 716                 /*
 717                  * If we are using indirect segments we need to account
 718                  * for the indirect grefs used in the request.
 719                  */
 720                 max_grefs += INDIRECT_GREFS(max_grefs);
 721
 722         /*
 723          * We have to reserve 'max_grefs' grants because persistent
 724          * grants are shared by all rings.
 725          */
 726         if (max_grefs > 0)
 727                 if (gnttab_alloc_grant_references(max_grefs, &setup.gref_head) < 0) {
 728                         gnttab_request_free_callback(
 729                                 &rinfo->callback,
 730                                 blkif_restart_queue_callback,
 731                                 rinfo,
 732                                 max_grefs);
 733                         return 1;
 734                 }
 735
 736         /* Fill out a communications ring structure. */
 737         id = blkif_ring_get_request(rinfo, req, &ring_req);
 738
 739         num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 740         num_grant = 0;
 741         /* Calculate the number of grant used */
 742         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
 743                num_grant += gnttab_count_grant(sg->offset, sg->length);
 744
 745         require_extra_req = info->max_indirect_segments == 0 &&
 746                 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
 747         BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
 748
 749         rinfo->shadow[id].num_sg = num_sg;
 750         if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
 751             likely(!require_extra_req)) {
 752                 /*
 753                  * The indirect operation can only be a BLKIF_OP_READ or
 754                  * BLKIF_OP_WRITE
 755                  */
 756                 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
 757                 ring_req->operation = BLKIF_OP_INDIRECT;
 758                 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
 759                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 760                 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
 761                 ring_req->u.indirect.handle = info->handle;
 762                 ring_req->u.indirect.nr_segments = num_grant;
 763         } else {
 764                 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 765                 ring_req->u.rw.handle = info->handle;
 766                 ring_req->operation = rq_data_dir(req) ?
 767                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 768                 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
 769                         /*
 770                          * Ideally we can do an unordered flush-to-disk.
 771                          * In case the backend onlysupports barriers, use that.
 772                          * A barrier request a superset of FUA, so we can
 773                          * implement it the same way.  (It's also a FLUSH+FUA,
 774                          * since it is guaranteed ordered WRT previous writes.)
 775                          */
 776                         if (info->feature_flush && info->feature_fua)
 777                                 ring_req->operation =
 778                                         BLKIF_OP_WRITE_BARRIER;
 779                         else if (info->feature_flush)
 780                                 ring_req->operation =
 781                                         BLKIF_OP_FLUSH_DISKCACHE;
 782                         else
 783                                 ring_req->operation = 0;
 784                 }
 785                 ring_req->u.rw.nr_segments = num_grant;
 786                 if (unlikely(require_extra_req)) {
 787                         extra_id = blkif_ring_get_request(rinfo, req,
 788                                                           &extra_ring_req);
 789                         /*
 790                          * Only the first request contains the scatter-gather
 791                          * list.
 792                          */
 793                         rinfo->shadow[extra_id].num_sg = 0;
 794
 795                         blkif_setup_extra_req(ring_req, extra_ring_req);
 796
 797                         /* Link the 2 requests together */
 798                         rinfo->shadow[extra_id].associated_id = id;
 799                         rinfo->shadow[id].associated_id = extra_id;
 800                 }
 801         }
 802
 803         setup.ring_req = ring_req;
 804         setup.id = id;
 805
 806         setup.require_extra_req = require_extra_req;
 807         if (unlikely(require_extra_req))
 808                 setup.extra_ring_req = extra_ring_req;
 809
 810         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
 811                 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
 812
 813                 if (setup.need_copy) {
 814                         setup.bvec_off = sg->offset;
 815                         setup.bvec_data = kmap_atomic(sg_page(sg));
 816                 }
 817
 818                 gnttab_foreach_grant_in_range(sg_page(sg),
 819                                               sg->offset,
 820                                               sg->length,
 821                                               blkif_setup_rw_req_grant,
 822                                               &setup);
 823
 824                 if (setup.need_copy)
 825                         kunmap_atomic(setup.bvec_data);
 826         }
 827         if (setup.segments)
 828                 kunmap_atomic(setup.segments);
 829
 830         /* Keep a private copy so we can reissue requests when recovering. */
 831         rinfo->shadow[id].req = *ring_req;
 832         if (unlikely(require_extra_req))
 833                 rinfo->shadow[extra_id].req = *extra_ring_req;
 834
 835         if (max_grefs > 0)
 836                 gnttab_free_grant_references(setup.gref_head);
 837
 838         return 0;
 839 }
 840
 841 /*
 842  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 843  * and writes are handled as expected.
 844  *
 845  * @req: a request struct
 846  */
 847 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
 848 {
 849         if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
 850                 return 1;
 851
 852         if (unlikely(req_op(req) == REQ_OP_DISCARD ||
 853                      req_op(req) == REQ_OP_SECURE_ERASE))
 854                 return blkif_queue_discard_req(req, rinfo);
 855         else
 856                 return blkif_queue_rw_req(req, rinfo);
 857 }
 858
 859 static inline void flush_requests(struct blkfront_ring_info *rinfo)
 860 {
 861         int notify;
 862
 863         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
 864
 865         if (notify)
 866                 notify_remote_via_irq(rinfo->irq);
 867 }
 868
 869 static inline bool blkif_request_flush_invalid(struct request *req,
 870                                                struct blkfront_info *info)
 871 {
 872         return (blk_rq_is_passthrough(req) ||
 873                 ((req_op(req) == REQ_OP_FLUSH) &&
 874                  !info->feature_flush) ||
 875                 ((req->cmd_flags & REQ_FUA) &&
 876                  !info->feature_fua));
 877 }
 878
 879 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
 880                           const struct blk_mq_queue_data *qd)
 881 {
 882         unsigned long flags;
 883         int qid = hctx->queue_num;
 884         struct blkfront_info *info = hctx->queue->queuedata;
 885         struct blkfront_ring_info *rinfo = NULL;
 886
 887         BUG_ON(info->nr_rings <= qid);
 888         rinfo = &info->rinfo[qid];
 889         blk_mq_start_request(qd->rq);
 890         spin_lock_irqsave(&rinfo->ring_lock, flags);
 891         if (RING_FULL(&rinfo->ring))
 892                 goto out_busy;
 893
 894         if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
 895                 goto out_err;
 896
 897         if (blkif_queue_request(qd->rq, rinfo))
 898                 goto out_busy;
 899
 900         flush_requests(rinfo);
 901         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 902         return BLK_STS_OK;
 903
 904 out_err:
 905         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 906         return BLK_STS_IOERR;
 907
 908 out_busy:
 909         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 910         blk_mq_stop_hw_queue(hctx);
 911         return BLK_STS_RESOURCE;
 912 }
 913
 914 static void blkif_complete_rq(struct request *rq)
 915 {
 916         blk_mq_end_request(rq, blkif_req(rq)->error);
 917 }
 918
 919 static const struct blk_mq_ops blkfront_mq_ops = {
 920         .queue_rq = blkif_queue_rq,
 921         .complete = blkif_complete_rq,
 922 };
 923
 924 static void blkif_set_queue_limits(struct blkfront_info *info)
 925 {
 926         struct request_queue *rq = info->rq;
 927         struct gendisk *gd = info->gd;
 928         unsigned int segments = info->max_indirect_segments ? :
 929                                 BLKIF_MAX_SEGMENTS_PER_REQUEST;
 930
 931         queue_flag_set_unlocked(QUEUE_FLAG_VIRT, rq);
 932
 933         if (info->feature_discard) {
 934                 queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, rq);
 935                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
 936                 rq->limits.discard_granularity = info->discard_granularity;
 937                 rq->limits.discard_alignment = info->discard_alignment;
 938                 if (info->feature_secdiscard)
 939                         queue_flag_set_unlocked(QUEUE_FLAG_SECERASE, rq);
 940         }
 941
 942         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 943         blk_queue_logical_block_size(rq, info->sector_size);
 944         blk_queue_physical_block_size(rq, info->physical_sector_size);
 945         blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
 946
 947         /* Each segment in a request is up to an aligned page in size. */
 948         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 949         blk_queue_max_segment_size(rq, PAGE_SIZE);
 950
 951         /* Ensure a merged request will fit in a single I/O ring slot. */
 952         blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
 953
 954         /* Make sure buffer addresses are sector-aligned. */
 955         blk_queue_dma_alignment(rq, 511);
 956 }
 957
 958 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 959                                 unsigned int physical_sector_size)
 960 {
 961         struct request_queue *rq;
 962         struct blkfront_info *info = gd->private_data;
 963
 964         memset(&info->tag_set, 0, sizeof(info->tag_set));
 965         info->tag_set.ops = &blkfront_mq_ops;
 966         info->tag_set.nr_hw_queues = info->nr_rings;
 967         if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
 968                 /*
 969                  * When indirect descriptior is not supported, the I/O request
 970                  * will be split between multiple request in the ring.
 971                  * To avoid problems when sending the request, divide by
 972                  * 2 the depth of the queue.
 973                  */
 974                 info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
 975         } else
 976                 info->tag_set.queue_depth = BLK_RING_SIZE(info);
 977         info->tag_set.numa_node = NUMA_NO_NODE;
 978         info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
 979         info->tag_set.cmd_size = sizeof(struct blkif_req);
 980         info->tag_set.driver_data = info;
 981
 982         if (blk_mq_alloc_tag_set(&info->tag_set))
 983                 return -EINVAL;
 984         rq = blk_mq_init_queue(&info->tag_set);
 985         if (IS_ERR(rq)) {
 986                 blk_mq_free_tag_set(&info->tag_set);
 987                 return PTR_ERR(rq);
 988         }
 989
 990         rq->queuedata = info;
 991         info->rq = gd->queue = rq;
 992         info->gd = gd;
 993         info->sector_size = sector_size;
 994         info->physical_sector_size = physical_sector_size;
 995         blkif_set_queue_limits(info);
 996
 997         return 0;
 998 }
 999
1000 static const char *flush_info(struct blkfront_info *info)
1001 {
1002         if (info->feature_flush && info->feature_fua)
1003                 return "barrier: enabled;";
1004         else if (info->feature_flush)
1005                 return "flush diskcache: enabled;";
1006         else
1007                 return "barrier or flush: disabled;";
1008 }
1009
1010 static void xlvbd_flush(struct blkfront_info *info)
1011 {
1012         blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
1013                               info->feature_fua ? true : false);
1014         pr_info("blkfront: %s: %s %s %s %s %s\n",
1015                 info->gd->disk_name, flush_info(info),
1016                 "persistent grants:", info->feature_persistent ?
1017                 "enabled;" : "disabled;", "indirect descriptors:",
1018                 info->max_indirect_segments ? "enabled;" : "disabled;");
1019 }
1020
1021 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1022 {
1023         int major;
1024         major = BLKIF_MAJOR(vdevice);
1025         *minor = BLKIF_MINOR(vdevice);
1026         switch (major) {
1027                 case XEN_IDE0_MAJOR:
1028                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1029                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
1030                                 EMULATED_HD_DISK_MINOR_OFFSET;
1031                         break;
1032                 case XEN_IDE1_MAJOR:
1033                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1034                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1035                                 EMULATED_HD_DISK_MINOR_OFFSET;
1036                         break;
1037                 case XEN_SCSI_DISK0_MAJOR:
1038                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1039                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1040                         break;
1041                 case XEN_SCSI_DISK1_MAJOR:
1042                 case XEN_SCSI_DISK2_MAJOR:
1043                 case XEN_SCSI_DISK3_MAJOR:
1044                 case XEN_SCSI_DISK4_MAJOR:
1045                 case XEN_SCSI_DISK5_MAJOR:
1046                 case XEN_SCSI_DISK6_MAJOR:
1047                 case XEN_SCSI_DISK7_MAJOR:
1048                         *offset = (*minor / PARTS_PER_DISK) +
1049                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1050                                 EMULATED_SD_DISK_NAME_OFFSET;
1051                         *minor = *minor +
1052                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1053                                 EMULATED_SD_DISK_MINOR_OFFSET;
1054                         break;
1055                 case XEN_SCSI_DISK8_MAJOR:
1056                 case XEN_SCSI_DISK9_MAJOR:
1057                 case XEN_SCSI_DISK10_MAJOR:
1058                 case XEN_SCSI_DISK11_MAJOR:
1059                 case XEN_SCSI_DISK12_MAJOR:
1060                 case XEN_SCSI_DISK13_MAJOR:
1061                 case XEN_SCSI_DISK14_MAJOR:
1062                 case XEN_SCSI_DISK15_MAJOR:
1063                         *offset = (*minor / PARTS_PER_DISK) +
1064                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1065                                 EMULATED_SD_DISK_NAME_OFFSET;
1066                         *minor = *minor +
1067                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1068                                 EMULATED_SD_DISK_MINOR_OFFSET;
1069                         break;
1070                 case XENVBD_MAJOR:
1071                         *offset = *minor / PARTS_PER_DISK;
1072                         break;
1073                 default:
1074                         printk(KERN_WARNING "blkfront: your disk configuration is "
1075                                         "incorrect, please use an xvd device instead\n");
1076                         return -ENODEV;
1077         }
1078         return 0;
1079 }
1080
1081 static char *encode_disk_name(char *ptr, unsigned int n)
1082 {
1083         if (n >= 26)
1084                 ptr = encode_disk_name(ptr, n / 26 - 1);
1085         *ptr = 'a' + n % 26;
1086         return ptr + 1;
1087 }
1088
1089 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1090                                struct blkfront_info *info,
1091                                u16 vdisk_info, u16 sector_size,
1092                                unsigned int physical_sector_size)
1093 {
1094         struct gendisk *gd;
1095         int nr_minors = 1;
1096         int err;
1097         unsigned int offset;
1098         int minor;
1099         int nr_parts;
1100         char *ptr;
1101
1102         BUG_ON(info->gd != NULL);
1103         BUG_ON(info->rq != NULL);
1104
1105         if ((info->vdevice>>EXT_SHIFT) > 1) {
1106                 /* this is above the extended range; something is wrong */
1107                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1108                 return -ENODEV;
1109         }
1110
1111         if (!VDEV_IS_EXTENDED(info->vdevice)) {
1112                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1113                 if (err)
1114                         return err;
1115                 nr_parts = PARTS_PER_DISK;
1116         } else {
1117                 minor = BLKIF_MINOR_EXT(info->vdevice);
1118                 nr_parts = PARTS_PER_EXT_DISK;
1119                 offset = minor / nr_parts;
1120                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1121                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1122                                         "emulated IDE disks,\n\t choose an xvd device name"
1123                                         "from xvde on\n", info->vdevice);
1124         }
1125         if (minor >> MINORBITS) {
1126                 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1127                         info->vdevice, minor);
1128                 return -ENODEV;
1129         }
1130
1131         if ((minor % nr_parts) == 0)
1132                 nr_minors = nr_parts;
1133
1134         err = xlbd_reserve_minors(minor, nr_minors);
1135         if (err)
1136                 goto out;
1137         err = -ENODEV;
1138
1139         gd = alloc_disk(nr_minors);
1140         if (gd == NULL)
1141                 goto release;
1142
1143         strcpy(gd->disk_name, DEV_NAME);
1144         ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1145         BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1146         if (nr_minors > 1)
1147                 *ptr = 0;
1148         else
1149                 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1150                          "%d", minor & (nr_parts - 1));
1151
1152         gd->major = XENVBD_MAJOR;
1153         gd->first_minor = minor;
1154         gd->fops = &xlvbd_block_fops;
1155         gd->private_data = info;
1156         set_capacity(gd, capacity);
1157
1158         if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
1159                 del_gendisk(gd);
1160                 goto release;
1161         }
1162
1163         xlvbd_flush(info);
1164
1165         if (vdisk_info & VDISK_READONLY)
1166                 set_disk_ro(gd, 1);
1167
1168         if (vdisk_info & VDISK_REMOVABLE)
1169                 gd->flags |= GENHD_FL_REMOVABLE;
1170
1171         if (vdisk_info & VDISK_CDROM)
1172                 gd->flags |= GENHD_FL_CD;
1173
1174         return 0;
1175
1176  release:
1177         xlbd_release_minors(minor, nr_minors);
1178  out:
1179         return err;
1180 }
1181
1182 static void xlvbd_release_gendisk(struct blkfront_info *info)
1183 {
1184         unsigned int minor, nr_minors, i;
1185
1186         if (info->rq == NULL)
1187                 return;
1188
1189         /* No more blkif_request(). */
1190         blk_mq_stop_hw_queues(info->rq);
1191
1192         for (i = 0; i < info->nr_rings; i++) {
1193                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1194
1195                 /* No more gnttab callback work. */
1196                 gnttab_cancel_free_callback(&rinfo->callback);
1197
1198                 /* Flush gnttab callback work. Must be done with no locks held. */
1199                 flush_work(&rinfo->work);
1200         }
1201
1202         del_gendisk(info->gd);
1203
1204         minor = info->gd->first_minor;
1205         nr_minors = info->gd->minors;
1206         xlbd_release_minors(minor, nr_minors);
1207
1208         blk_cleanup_queue(info->rq);
1209         blk_mq_free_tag_set(&info->tag_set);
1210         info->rq = NULL;
1211
1212         put_disk(info->gd);
1213         info->gd = NULL;
1214 }
1215
1216 /* Already hold rinfo->ring_lock. */
1217 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1218 {
1219         if (!RING_FULL(&rinfo->ring))
1220                 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1221 }
1222
1223 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1224 {
1225         unsigned long flags;
1226
1227         spin_lock_irqsave(&rinfo->ring_lock, flags);
1228         kick_pending_request_queues_locked(rinfo);
1229         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1230 }
1231
1232 static void blkif_restart_queue(struct work_struct *work)
1233 {
1234         struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1235
1236         if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1237                 kick_pending_request_queues(rinfo);
1238 }
1239
1240 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1241 {
1242         struct grant *persistent_gnt, *n;
1243         struct blkfront_info *info = rinfo->dev_info;
1244         int i, j, segs;
1245
1246         /*
1247          * Remove indirect pages, this only happens when using indirect
1248          * descriptors but not persistent grants
1249          */
1250         if (!list_empty(&rinfo->indirect_pages)) {
1251                 struct page *indirect_page, *n;
1252
1253                 BUG_ON(info->feature_persistent);
1254                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1255                         list_del(&indirect_page->lru);
1256                         __free_page(indirect_page);
1257                 }
1258         }
1259
1260         /* Remove all persistent grants. */
1261         if (!list_empty(&rinfo->grants)) {
1262                 list_for_each_entry_safe(persistent_gnt, n,
1263                                          &rinfo->grants, node) {
1264                         list_del(&persistent_gnt->node);
1265                         if (persistent_gnt->gref != GRANT_INVALID_REF) {
1266                                 gnttab_end_foreign_access(persistent_gnt->gref,
1267                                                           0, 0UL);
1268                                 rinfo->persistent_gnts_c--;
1269                         }
1270                         if (info->feature_persistent)
1271                                 __free_page(persistent_gnt->page);
1272                         kfree(persistent_gnt);
1273                 }
1274         }
1275         BUG_ON(rinfo->persistent_gnts_c != 0);
1276
1277         for (i = 0; i < BLK_RING_SIZE(info); i++) {
1278                 /*
1279                  * Clear persistent grants present in requests already
1280                  * on the shared ring
1281                  */
1282                 if (!rinfo->shadow[i].request)
1283                         goto free_shadow;
1284
1285                 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1286                        rinfo->shadow[i].req.u.indirect.nr_segments :
1287                        rinfo->shadow[i].req.u.rw.nr_segments;
1288                 for (j = 0; j < segs; j++) {
1289                         persistent_gnt = rinfo->shadow[i].grants_used[j];
1290                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1291                         if (info->feature_persistent)
1292                                 __free_page(persistent_gnt->page);
1293                         kfree(persistent_gnt);
1294                 }
1295
1296                 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1297                         /*
1298                          * If this is not an indirect operation don't try to
1299                          * free indirect segments
1300                          */
1301                         goto free_shadow;
1302
1303                 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1304                         persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1305                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1306                         __free_page(persistent_gnt->page);
1307                         kfree(persistent_gnt);
1308                 }
1309
1310 free_shadow:
1311                 kfree(rinfo->shadow[i].grants_used);
1312                 rinfo->shadow[i].grants_used = NULL;
1313                 kfree(rinfo->shadow[i].indirect_grants);
1314                 rinfo->shadow[i].indirect_grants = NULL;
1315                 kfree(rinfo->shadow[i].sg);
1316                 rinfo->shadow[i].sg = NULL;
1317         }
1318
1319         /* No more gnttab callback work. */
1320         gnttab_cancel_free_callback(&rinfo->callback);
1321
1322         /* Flush gnttab callback work. Must be done with no locks held. */
1323         flush_work(&rinfo->work);
1324
1325         /* Free resources associated with old device channel. */
1326         for (i = 0; i < info->nr_ring_pages; i++) {
1327                 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1328                         gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1329                         rinfo->ring_ref[i] = GRANT_INVALID_REF;
1330                 }
1331         }
1332         free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
1333         rinfo->ring.sring = NULL;
1334
1335         if (rinfo->irq)
1336                 unbind_from_irqhandler(rinfo->irq, rinfo);
1337         rinfo->evtchn = rinfo->irq = 0;
1338 }
1339
1340 static void blkif_free(struct blkfront_info *info, int suspend)
1341 {
1342         unsigned int i;
1343
1344         /* Prevent new requests being issued until we fix things up. */
1345         info->connected = suspend ?
1346                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1347         /* No more blkif_request(). */
1348         if (info->rq)
1349                 blk_mq_stop_hw_queues(info->rq);
1350
1351         for (i = 0; i < info->nr_rings; i++)
1352                 blkif_free_ring(&info->rinfo[i]);
1353
1354         kfree(info->rinfo);
1355         info->rinfo = NULL;
1356         info->nr_rings = 0;
1357 }
1358
1359 struct copy_from_grant {
1360         const struct blk_shadow *s;
1361         unsigned int grant_idx;
1362         unsigned int bvec_offset;
1363         char *bvec_data;
1364 };
1365
1366 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1367                                   unsigned int len, void *data)
1368 {
1369         struct copy_from_grant *info = data;
1370         char *shared_data;
1371         /* Convenient aliases */
1372         const struct blk_shadow *s = info->s;
1373
1374         shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1375
1376         memcpy(info->bvec_data + info->bvec_offset,
1377                shared_data + offset, len);
1378
1379         info->bvec_offset += len;
1380         info->grant_idx++;
1381
1382         kunmap_atomic(shared_data);
1383 }
1384
1385 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1386 {
1387         switch (rsp)
1388         {
1389         case BLKIF_RSP_OKAY:
1390                 return REQ_DONE;
1391         case BLKIF_RSP_EOPNOTSUPP:
1392                 return REQ_EOPNOTSUPP;
1393         case BLKIF_RSP_ERROR:
1394                 /* Fallthrough. */
1395         default:
1396                 return REQ_ERROR;
1397         }
1398 }
1399
1400 /*
1401  * Get the final status of the block request based on two ring response
1402  */
1403 static int blkif_get_final_status(enum blk_req_status s1,
1404                                   enum blk_req_status s2)
1405 {
1406         BUG_ON(s1 == REQ_WAITING);
1407         BUG_ON(s2 == REQ_WAITING);
1408
1409         if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1410                 return BLKIF_RSP_ERROR;
1411         else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1412                 return BLKIF_RSP_EOPNOTSUPP;
1413         return BLKIF_RSP_OKAY;
1414 }
1415
1416 static bool blkif_completion(unsigned long *id,
1417                              struct blkfront_ring_info *rinfo,
1418                              struct blkif_response *bret)
1419 {
1420         int i = 0;
1421         struct scatterlist *sg;
1422         int num_sg, num_grant;
1423         struct blkfront_info *info = rinfo->dev_info;
1424         struct blk_shadow *s = &rinfo->shadow[*id];
1425         struct copy_from_grant data = {
1426                 .grant_idx = 0,
1427         };
1428
1429         num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1430                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1431
1432         /* The I/O request may be split in two. */
1433         if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1434                 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1435
1436                 /* Keep the status of the current response in shadow. */
1437                 s->status = blkif_rsp_to_req_status(bret->status);
1438
1439                 /* Wait the second response if not yet here. */
1440                 if (s2->status == REQ_WAITING)
1441                         return 0;
1442
1443                 bret->status = blkif_get_final_status(s->status,
1444                                                       s2->status);
1445
1446                 /*
1447                  * All the grants is stored in the first shadow in order
1448                  * to make the completion code simpler.
1449                  */
1450                 num_grant += s2->req.u.rw.nr_segments;
1451
1452                 /*
1453                  * The two responses may not come in order. Only the
1454                  * first request will store the scatter-gather list.
1455                  */
1456                 if (s2->num_sg != 0) {
1457                         /* Update "id" with the ID of the first response. */
1458                         *id = s->associated_id;
1459                         s = s2;
1460                 }
1461
1462                 /*
1463                  * We don't need anymore the second request, so recycling
1464                  * it now.
1465                  */
1466                 if (add_id_to_freelist(rinfo, s->associated_id))
1467                         WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1468                              info->gd->disk_name, s->associated_id);
1469         }
1470
1471         data.s = s;
1472         num_sg = s->num_sg;
1473
1474         if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1475                 for_each_sg(s->sg, sg, num_sg, i) {
1476                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1477
1478                         data.bvec_offset = sg->offset;
1479                         data.bvec_data = kmap_atomic(sg_page(sg));
1480
1481                         gnttab_foreach_grant_in_range(sg_page(sg),
1482                                                       sg->offset,
1483                                                       sg->length,
1484                                                       blkif_copy_from_grant,
1485                                                       &data);
1486
1487                         kunmap_atomic(data.bvec_data);
1488                 }
1489         }
1490         /* Add the persistent grant into the list of free grants */
1491         for (i = 0; i < num_grant; i++) {
1492                 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1493                         /*
1494                          * If the grant is still mapped by the backend (the
1495                          * backend has chosen to make this grant persistent)
1496                          * we add it at the head of the list, so it will be
1497                          * reused first.
1498                          */
1499                         if (!info->feature_persistent)
1500                                 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1501                                                      s->grants_used[i]->gref);
1502                         list_add(&s->grants_used[i]->node, &rinfo->grants);
1503                         rinfo->persistent_gnts_c++;
1504                 } else {
1505                         /*
1506                          * If the grant is not mapped by the backend we end the
1507                          * foreign access and add it to the tail of the list,
1508                          * so it will not be picked again unless we run out of
1509                          * persistent grants.
1510                          */
1511                         gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1512                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1513                         list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1514                 }
1515         }
1516         if (s->req.operation == BLKIF_OP_INDIRECT) {
1517                 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1518                         if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1519                                 if (!info->feature_persistent)
1520                                         pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1521                                                              s->indirect_grants[i]->gref);
1522                                 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1523                                 rinfo->persistent_gnts_c++;
1524                         } else {
1525                                 struct page *indirect_page;
1526
1527                                 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1528                                 /*
1529                                  * Add the used indirect page back to the list of
1530                                  * available pages for indirect grefs.
1531                                  */
1532                                 if (!info->feature_persistent) {
1533                                         indirect_page = s->indirect_grants[i]->page;
1534                                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
1535                                 }
1536                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1537                                 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1538                         }
1539                 }
1540         }
1541
1542         return 1;
1543 }
1544
1545 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1546 {
1547         struct request *req;
1548         struct blkif_response *bret;
1549         RING_IDX i, rp;
1550         unsigned long flags;
1551         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1552         struct blkfront_info *info = rinfo->dev_info;
1553
1554         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1555                 return IRQ_HANDLED;
1556
1557         spin_lock_irqsave(&rinfo->ring_lock, flags);
1558  again:
1559         rp = rinfo->ring.sring->rsp_prod;
1560         rmb(); /* Ensure we see queued responses up to 'rp'. */
1561
1562         for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1563                 unsigned long id;
1564
1565                 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1566                 id   = bret->id;
1567                 /*
1568                  * The backend has messed up and given us an id that we would
1569                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1570                  * look in get_id_from_freelist.
1571                  */
1572                 if (id >= BLK_RING_SIZE(info)) {
1573                         WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1574                              info->gd->disk_name, op_name(bret->operation), id);
1575                         /* We can't safely get the 'struct request' as
1576                          * the id is busted. */
1577                         continue;
1578                 }
1579                 req  = rinfo->shadow[id].request;
1580
1581                 if (bret->operation != BLKIF_OP_DISCARD) {
1582                         /*
1583                          * We may need to wait for an extra response if the
1584                          * I/O request is split in 2
1585                          */
1586                         if (!blkif_completion(&id, rinfo, bret))
1587                                 continue;
1588                 }
1589
1590                 if (add_id_to_freelist(rinfo, id)) {
1591                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1592                              info->gd->disk_name, op_name(bret->operation), id);
1593                         continue;
1594                 }
1595
1596                 if (bret->status == BLKIF_RSP_OKAY)
1597                         blkif_req(req)->error = BLK_STS_OK;
1598                 else
1599                         blkif_req(req)->error = BLK_STS_IOERR;
1600
1601                 switch (bret->operation) {
1602                 case BLKIF_OP_DISCARD:
1603                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1604                                 struct request_queue *rq = info->rq;
1605                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1606                                            info->gd->disk_name, op_name(bret->operation));
1607                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1608                                 info->feature_discard = 0;
1609                                 info->feature_secdiscard = 0;
1610                                 queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1611                                 queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1612                         }
1613                         break;
1614                 case BLKIF_OP_FLUSH_DISKCACHE:
1615                 case BLKIF_OP_WRITE_BARRIER:
1616                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1617                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1618                                        info->gd->disk_name, op_name(bret->operation));
1619                                 blkif_req(req)->error = -EOPNOTSUPP;
1620                         }
1621                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1622                                      rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1623                                 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1624                                        info->gd->disk_name, op_name(bret->operation));
1625                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1626                         }
1627                         if (unlikely(blkif_req(req)->error)) {
1628                                 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1629                                         blkif_req(req)->error = BLK_STS_OK;
1630                                 info->feature_fua = 0;
1631                                 info->feature_flush = 0;
1632                                 xlvbd_flush(info);
1633                         }
1634                         /* fall through */
1635                 case BLKIF_OP_READ:
1636                 case BLKIF_OP_WRITE:
1637                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
1638                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1639                                         "request: %x\n", bret->status);
1640
1641                         break;
1642                 default:
1643                         BUG();
1644                 }
1645
1646                 blk_mq_complete_request(req);
1647         }
1648
1649         rinfo->ring.rsp_cons = i;
1650
1651         if (i != rinfo->ring.req_prod_pvt) {
1652                 int more_to_do;
1653                 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1654                 if (more_to_do)
1655                         goto again;
1656         } else
1657                 rinfo->ring.sring->rsp_event = i + 1;
1658
1659         kick_pending_request_queues_locked(rinfo);
1660
1661         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1662
1663         return IRQ_HANDLED;
1664 }
1665
1666
1667 static int setup_blkring(struct xenbus_device *dev,
1668                          struct blkfront_ring_info *rinfo)
1669 {
1670         struct blkif_sring *sring;
1671         int err, i;
1672         struct blkfront_info *info = rinfo->dev_info;
1673         unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1674         grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1675
1676         for (i = 0; i < info->nr_ring_pages; i++)
1677                 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1678
1679         sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1680                                                        get_order(ring_size));
1681         if (!sring) {
1682                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1683                 return -ENOMEM;
1684         }
1685         SHARED_RING_INIT(sring);
1686         FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1687
1688         err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1689         if (err < 0) {
1690                 free_pages((unsigned long)sring, get_order(ring_size));
1691                 rinfo->ring.sring = NULL;
1692                 goto fail;
1693         }
1694         for (i = 0; i < info->nr_ring_pages; i++)
1695                 rinfo->ring_ref[i] = gref[i];
1696
1697         err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1698         if (err)
1699                 goto fail;
1700
1701         err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1702                                         "blkif", rinfo);
1703         if (err <= 0) {
1704                 xenbus_dev_fatal(dev, err,
1705                                  "bind_evtchn_to_irqhandler failed");
1706                 goto fail;
1707         }
1708         rinfo->irq = err;
1709
1710         return 0;
1711 fail:
1712         blkif_free(info, 0);
1713         return err;
1714 }
1715
1716 /*
1717  * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1718  * ring buffer may have multi pages depending on ->nr_ring_pages.
1719  */
1720 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1721                                 struct blkfront_ring_info *rinfo, const char *dir)
1722 {
1723         int err;
1724         unsigned int i;
1725         const char *message = NULL;
1726         struct blkfront_info *info = rinfo->dev_info;
1727
1728         if (info->nr_ring_pages == 1) {
1729                 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1730                 if (err) {
1731                         message = "writing ring-ref";
1732                         goto abort_transaction;
1733                 }
1734         } else {
1735                 for (i = 0; i < info->nr_ring_pages; i++) {
1736                         char ring_ref_name[RINGREF_NAME_LEN];
1737
1738                         snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1739                         err = xenbus_printf(xbt, dir, ring_ref_name,
1740                                             "%u", rinfo->ring_ref[i]);
1741                         if (err) {
1742                                 message = "writing ring-ref";
1743                                 goto abort_transaction;
1744                         }
1745                 }
1746         }
1747
1748         err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1749         if (err) {
1750                 message = "writing event-channel";
1751                 goto abort_transaction;
1752         }
1753
1754         return 0;
1755
1756 abort_transaction:
1757         xenbus_transaction_end(xbt, 1);
1758         if (message)
1759                 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1760
1761         return err;
1762 }
1763
1764 /* Common code used when first setting up, and when resuming. */
1765 static int talk_to_blkback(struct xenbus_device *dev,
1766                            struct blkfront_info *info)
1767 {
1768         const char *message = NULL;
1769         struct xenbus_transaction xbt;
1770         int err;
1771         unsigned int i, max_page_order;
1772         unsigned int ring_page_order;
1773
1774         max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1775                                               "max-ring-page-order", 0);
1776         ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1777         info->nr_ring_pages = 1 << ring_page_order;
1778
1779         for (i = 0; i < info->nr_rings; i++) {
1780                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1781
1782                 /* Create shared ring, alloc event channel. */
1783                 err = setup_blkring(dev, rinfo);
1784                 if (err)
1785                         goto destroy_blkring;
1786         }
1787
1788 again:
1789         err = xenbus_transaction_start(&xbt);
1790         if (err) {
1791                 xenbus_dev_fatal(dev, err, "starting transaction");
1792                 goto destroy_blkring;
1793         }
1794
1795         if (info->nr_ring_pages > 1) {
1796                 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1797                                     ring_page_order);
1798                 if (err) {
1799                         message = "writing ring-page-order";
1800                         goto abort_transaction;
1801                 }
1802         }
1803
1804         /* We already got the number of queues/rings in _probe */
1805         if (info->nr_rings == 1) {
1806                 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1807                 if (err)
1808                         goto destroy_blkring;
1809         } else {
1810                 char *path;
1811                 size_t pathsize;
1812
1813                 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1814                                     info->nr_rings);
1815                 if (err) {
1816                         message = "writing multi-queue-num-queues";
1817                         goto abort_transaction;
1818                 }
1819
1820                 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1821                 path = kmalloc(pathsize, GFP_KERNEL);
1822                 if (!path) {
1823                         err = -ENOMEM;
1824                         message = "ENOMEM while writing ring references";
1825                         goto abort_transaction;
1826                 }
1827
1828                 for (i = 0; i < info->nr_rings; i++) {
1829                         memset(path, 0, pathsize);
1830                         snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1831                         err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1832                         if (err) {
1833                                 kfree(path);
1834                                 goto destroy_blkring;
1835                         }
1836                 }
1837                 kfree(path);
1838         }
1839         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1840                             XEN_IO_PROTO_ABI_NATIVE);
1841         if (err) {
1842                 message = "writing protocol";
1843                 goto abort_transaction;
1844         }
1845         err = xenbus_printf(xbt, dev->nodename,
1846                             "feature-persistent", "%u", 1);
1847         if (err)
1848                 dev_warn(&dev->dev,
1849                          "writing persistent grants feature to xenbus");
1850
1851         err = xenbus_transaction_end(xbt, 0);
1852         if (err) {
1853                 if (err == -EAGAIN)
1854                         goto again;
1855                 xenbus_dev_fatal(dev, err, "completing transaction");
1856                 goto destroy_blkring;
1857         }
1858
1859         for (i = 0; i < info->nr_rings; i++) {
1860                 unsigned int j;
1861                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1862
1863                 for (j = 0; j < BLK_RING_SIZE(info); j++)
1864                         rinfo->shadow[j].req.u.rw.id = j + 1;
1865                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1866         }
1867         xenbus_switch_state(dev, XenbusStateInitialised);
1868
1869         return 0;
1870
1871  abort_transaction:
1872         xenbus_transaction_end(xbt, 1);
1873         if (message)
1874                 xenbus_dev_fatal(dev, err, "%s", message);
1875  destroy_blkring:
1876         blkif_free(info, 0);
1877
1878         kfree(info);
1879         dev_set_drvdata(&dev->dev, NULL);
1880
1881         return err;
1882 }
1883
1884 static int negotiate_mq(struct blkfront_info *info)
1885 {
1886         unsigned int backend_max_queues;
1887         unsigned int i;
1888
1889         BUG_ON(info->nr_rings);
1890
1891         /* Check if backend supports multiple queues. */
1892         backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1893                                                   "multi-queue-max-queues", 1);
1894         info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1895         /* We need at least one ring. */
1896         if (!info->nr_rings)
1897                 info->nr_rings = 1;
1898
1899         info->rinfo = kzalloc(sizeof(struct blkfront_ring_info) * info->nr_rings, GFP_KERNEL);
1900         if (!info->rinfo) {
1901                 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1902                 return -ENOMEM;
1903         }
1904
1905         for (i = 0; i < info->nr_rings; i++) {
1906                 struct blkfront_ring_info *rinfo;
1907
1908                 rinfo = &info->rinfo[i];
1909                 INIT_LIST_HEAD(&rinfo->indirect_pages);
1910                 INIT_LIST_HEAD(&rinfo->grants);
1911                 rinfo->dev_info = info;
1912                 INIT_WORK(&rinfo->work, blkif_restart_queue);
1913                 spin_lock_init(&rinfo->ring_lock);
1914         }
1915         return 0;
1916 }
1917 /**
1918  * Entry point to this code when a new device is created.  Allocate the basic
1919  * structures and the ring buffer for communication with the backend, and
1920  * inform the backend of the appropriate details for those.  Switch to
1921  * Initialised state.
1922  */
1923 static int blkfront_probe(struct xenbus_device *dev,
1924                           const struct xenbus_device_id *id)
1925 {
1926         int err, vdevice;
1927         struct blkfront_info *info;
1928
1929         /* FIXME: Use dynamic device id if this is not set. */
1930         err = xenbus_scanf(XBT_NIL, dev->nodename,
1931                            "virtual-device", "%i", &vdevice);
1932         if (err != 1) {
1933                 /* go looking in the extended area instead */
1934                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1935                                    "%i", &vdevice);
1936                 if (err != 1) {
1937                         xenbus_dev_fatal(dev, err, "reading virtual-device");
1938                         return err;
1939                 }
1940         }
1941
1942         if (xen_hvm_domain()) {
1943                 char *type;
1944                 int len;
1945                 /* no unplug has been done: do not hook devices != xen vbds */
1946                 if (xen_has_pv_and_legacy_disk_devices()) {
1947                         int major;
1948
1949                         if (!VDEV_IS_EXTENDED(vdevice))
1950                                 major = BLKIF_MAJOR(vdevice);
1951                         else
1952                                 major = XENVBD_MAJOR;
1953
1954                         if (major != XENVBD_MAJOR) {
1955                                 printk(KERN_INFO
1956                                                 "%s: HVM does not support vbd %d as xen block device\n",
1957                                                 __func__, vdevice);
1958                                 return -ENODEV;
1959                         }
1960                 }
1961                 /* do not create a PV cdrom device if we are an HVM guest */
1962                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1963                 if (IS_ERR(type))
1964                         return -ENODEV;
1965                 if (strncmp(type, "cdrom", 5) == 0) {
1966                         kfree(type);
1967                         return -ENODEV;
1968                 }
1969                 kfree(type);
1970         }
1971         info = kzalloc(sizeof(*info), GFP_KERNEL);
1972         if (!info) {
1973                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1974                 return -ENOMEM;
1975         }
1976
1977         info->xbdev = dev;
1978         err = negotiate_mq(info);
1979         if (err) {
1980                 kfree(info);
1981                 return err;
1982         }
1983
1984         mutex_init(&info->mutex);
1985         info->vdevice = vdevice;
1986         info->connected = BLKIF_STATE_DISCONNECTED;
1987
1988         /* Front end dir is a number, which is used as the id. */
1989         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1990         dev_set_drvdata(&dev->dev, info);
1991
1992         return 0;
1993 }
1994
1995 static int blkif_recover(struct blkfront_info *info)
1996 {
1997         unsigned int r_index;
1998         struct request *req, *n;
1999         int rc;
2000         struct bio *bio;
2001         unsigned int segs;
2002
2003         blkfront_gather_backend_features(info);
2004         /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2005         blkif_set_queue_limits(info);
2006         segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2007         blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2008
2009         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2010                 struct blkfront_ring_info *rinfo = &info->rinfo[r_index];
2011
2012                 rc = blkfront_setup_indirect(rinfo);
2013                 if (rc)
2014                         return rc;
2015         }
2016         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2017
2018         /* Now safe for us to use the shared ring */
2019         info->connected = BLKIF_STATE_CONNECTED;
2020
2021         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2022                 struct blkfront_ring_info *rinfo;
2023
2024                 rinfo = &info->rinfo[r_index];
2025                 /* Kick any other new requests queued since we resumed */
2026                 kick_pending_request_queues(rinfo);
2027         }
2028
2029         list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2030                 /* Requeue pending requests (flush or discard) */
2031                 list_del_init(&req->queuelist);
2032                 BUG_ON(req->nr_phys_segments > segs);
2033                 blk_mq_requeue_request(req, false);
2034         }
2035         blk_mq_start_stopped_hw_queues(info->rq, true);
2036         blk_mq_kick_requeue_list(info->rq);
2037
2038         while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2039                 /* Traverse the list of pending bios and re-queue them */
2040                 submit_bio(bio);
2041         }
2042
2043         return 0;
2044 }
2045
2046 /**
2047  * We are reconnecting to the backend, due to a suspend/resume, or a backend
2048  * driver restart.  We tear down our blkif structure and recreate it, but
2049  * leave the device-layer structures intact so that this is transparent to the
2050  * rest of the kernel.
2051  */
2052 static int blkfront_resume(struct xenbus_device *dev)
2053 {
2054         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2055         int err = 0;
2056         unsigned int i, j;
2057
2058         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2059
2060         bio_list_init(&info->bio_list);
2061         INIT_LIST_HEAD(&info->requests);
2062         for (i = 0; i < info->nr_rings; i++) {
2063                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2064                 struct bio_list merge_bio;
2065                 struct blk_shadow *shadow = rinfo->shadow;
2066
2067                 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2068                         /* Not in use? */
2069                         if (!shadow[j].request)
2070                                 continue;
2071
2072                         /*
2073                          * Get the bios in the request so we can re-queue them.
2074                          */
2075                         if (req_op(shadow[i].request) == REQ_OP_FLUSH ||
2076                             req_op(shadow[i].request) == REQ_OP_DISCARD ||
2077                             req_op(shadow[i].request) == REQ_OP_SECURE_ERASE ||
2078                             shadow[j].request->cmd_flags & REQ_FUA) {
2079                                 /*
2080                                  * Flush operations don't contain bios, so
2081                                  * we need to requeue the whole request
2082                                  *
2083                                  * XXX: but this doesn't make any sense for a
2084                                  * write with the FUA flag set..
2085                                  */
2086                                 list_add(&shadow[j].request->queuelist, &info->requests);
2087                                 continue;
2088                         }
2089                         merge_bio.head = shadow[j].request->bio;
2090                         merge_bio.tail = shadow[j].request->biotail;
2091                         bio_list_merge(&info->bio_list, &merge_bio);
2092                         shadow[j].request->bio = NULL;
2093                         blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2094                 }
2095         }
2096
2097         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2098
2099         err = negotiate_mq(info);
2100         if (err)
2101                 return err;
2102
2103         err = talk_to_blkback(dev, info);
2104         if (!err)
2105                 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2106
2107         /*
2108          * We have to wait for the backend to switch to
2109          * connected state, since we want to read which
2110          * features it supports.
2111          */
2112
2113         return err;
2114 }
2115
2116 static void blkfront_closing(struct blkfront_info *info)
2117 {
2118         struct xenbus_device *xbdev = info->xbdev;
2119         struct block_device *bdev = NULL;
2120
2121         mutex_lock(&info->mutex);
2122
2123         if (xbdev->state == XenbusStateClosing) {
2124                 mutex_unlock(&info->mutex);
2125                 return;
2126         }
2127
2128         if (info->gd)
2129                 bdev = bdget_disk(info->gd, 0);
2130
2131         mutex_unlock(&info->mutex);
2132
2133         if (!bdev) {
2134                 xenbus_frontend_closed(xbdev);
2135                 return;
2136         }
2137
2138         mutex_lock(&bdev->bd_mutex);
2139
2140         if (bdev->bd_openers) {
2141                 xenbus_dev_error(xbdev, -EBUSY,
2142                                  "Device in use; refusing to close");
2143                 xenbus_switch_state(xbdev, XenbusStateClosing);
2144         } else {
2145                 xlvbd_release_gendisk(info);
2146                 xenbus_frontend_closed(xbdev);
2147         }
2148
2149         mutex_unlock(&bdev->bd_mutex);
2150         bdput(bdev);
2151 }
2152
2153 static void blkfront_setup_discard(struct blkfront_info *info)
2154 {
2155         int err;
2156         unsigned int discard_granularity;
2157         unsigned int discard_alignment;
2158
2159         info->feature_discard = 1;
2160         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2161                 "discard-granularity", "%u", &discard_granularity,
2162                 "discard-alignment", "%u", &discard_alignment,
2163                 NULL);
2164         if (!err) {
2165                 info->discard_granularity = discard_granularity;
2166                 info->discard_alignment = discard_alignment;
2167         }
2168         info->feature_secdiscard =
2169                 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2170                                        0);
2171 }
2172
2173 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2174 {
2175         unsigned int psegs, grants;
2176         int err, i;
2177         struct blkfront_info *info = rinfo->dev_info;
2178
2179         if (info->max_indirect_segments == 0) {
2180                 if (!HAS_EXTRA_REQ)
2181                         grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2182                 else {
2183                         /*
2184                          * When an extra req is required, the maximum
2185                          * grants supported is related to the size of the
2186                          * Linux block segment.
2187                          */
2188                         grants = GRANTS_PER_PSEG;
2189                 }
2190         }
2191         else
2192                 grants = info->max_indirect_segments;
2193         psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2194
2195         err = fill_grant_buffer(rinfo,
2196                                 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2197         if (err)
2198                 goto out_of_memory;
2199
2200         if (!info->feature_persistent && info->max_indirect_segments) {
2201                 /*
2202                  * We are using indirect descriptors but not persistent
2203                  * grants, we need to allocate a set of pages that can be
2204                  * used for mapping indirect grefs
2205                  */
2206                 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2207
2208                 BUG_ON(!list_empty(&rinfo->indirect_pages));
2209                 for (i = 0; i < num; i++) {
2210                         struct page *indirect_page = alloc_page(GFP_NOIO);
2211                         if (!indirect_page)
2212                                 goto out_of_memory;
2213                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
2214                 }
2215         }
2216
2217         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2218                 rinfo->shadow[i].grants_used = kzalloc(
2219                         sizeof(rinfo->shadow[i].grants_used[0]) * grants,
2220                         GFP_NOIO);
2221                 rinfo->shadow[i].sg = kzalloc(sizeof(rinfo->shadow[i].sg[0]) * psegs, GFP_NOIO);
2222                 if (info->max_indirect_segments)
2223                         rinfo->shadow[i].indirect_grants = kzalloc(
2224                                 sizeof(rinfo->shadow[i].indirect_grants[0]) *
2225                                 INDIRECT_GREFS(grants),
2226                                 GFP_NOIO);
2227                 if ((rinfo->shadow[i].grants_used == NULL) ||
2228                         (rinfo->shadow[i].sg == NULL) ||
2229                      (info->max_indirect_segments &&
2230                      (rinfo->shadow[i].indirect_grants == NULL)))
2231                         goto out_of_memory;
2232                 sg_init_table(rinfo->shadow[i].sg, psegs);
2233         }
2234
2235
2236         return 0;
2237
2238 out_of_memory:
2239         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2240                 kfree(rinfo->shadow[i].grants_used);
2241                 rinfo->shadow[i].grants_used = NULL;
2242                 kfree(rinfo->shadow[i].sg);
2243                 rinfo->shadow[i].sg = NULL;
2244                 kfree(rinfo->shadow[i].indirect_grants);
2245                 rinfo->shadow[i].indirect_grants = NULL;
2246         }
2247         if (!list_empty(&rinfo->indirect_pages)) {
2248                 struct page *indirect_page, *n;
2249                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2250                         list_del(&indirect_page->lru);
2251                         __free_page(indirect_page);
2252                 }
2253         }
2254         return -ENOMEM;
2255 }
2256
2257 /*
2258  * Gather all backend feature-*
2259  */
2260 static void blkfront_gather_backend_features(struct blkfront_info *info)
2261 {
2262         unsigned int indirect_segments;
2263
2264         info->feature_flush = 0;
2265         info->feature_fua = 0;
2266
2267         /*
2268          * If there's no "feature-barrier" defined, then it means
2269          * we're dealing with a very old backend which writes
2270          * synchronously; nothing to do.
2271          *
2272          * If there are barriers, then we use flush.
2273          */
2274         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2275                 info->feature_flush = 1;
2276                 info->feature_fua = 1;
2277         }
2278
2279         /*
2280          * And if there is "feature-flush-cache" use that above
2281          * barriers.
2282          */
2283         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2284                                  0)) {
2285                 info->feature_flush = 1;
2286                 info->feature_fua = 0;
2287         }
2288
2289         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2290                 blkfront_setup_discard(info);
2291
2292         info->feature_persistent =
2293                 !!xenbus_read_unsigned(info->xbdev->otherend,
2294                                        "feature-persistent", 0);
2295
2296         indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2297                                         "feature-max-indirect-segments", 0);
2298         if (indirect_segments > xen_blkif_max_segments)
2299                 indirect_segments = xen_blkif_max_segments;
2300         if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2301                 indirect_segments = 0;
2302         info->max_indirect_segments = indirect_segments;
2303 }
2304
2305 /*
2306  * Invoked when the backend is finally 'ready' (and has told produced
2307  * the details about the physical device - #sectors, size, etc).
2308  */
2309 static void blkfront_connect(struct blkfront_info *info)
2310 {
2311         unsigned long long sectors;
2312         unsigned long sector_size;
2313         unsigned int physical_sector_size;
2314         unsigned int binfo;
2315         char *envp[] = { "RESIZE=1", NULL };
2316         int err, i;
2317
2318         switch (info->connected) {
2319         case BLKIF_STATE_CONNECTED:
2320                 /*
2321                  * Potentially, the back-end may be signalling
2322                  * a capacity change; update the capacity.
2323                  */
2324                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2325                                    "sectors", "%Lu", &sectors);
2326                 if (XENBUS_EXIST_ERR(err))
2327                         return;
2328                 printk(KERN_INFO "Setting capacity to %Lu\n",
2329                        sectors);
2330                 set_capacity(info->gd, sectors);
2331                 revalidate_disk(info->gd);
2332                 kobject_uevent_env(&disk_to_dev(info->gd)->kobj,
2333                                    KOBJ_CHANGE, envp);
2334
2335                 return;
2336         case BLKIF_STATE_SUSPENDED:
2337                 /*
2338                  * If we are recovering from suspension, we need to wait
2339                  * for the backend to announce it's features before
2340                  * reconnecting, at least we need to know if the backend
2341                  * supports indirect descriptors, and how many.
2342                  */
2343                 blkif_recover(info);
2344                 return;
2345
2346         default:
2347                 break;
2348         }
2349
2350         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2351                 __func__, info->xbdev->otherend);
2352
2353         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2354                             "sectors", "%llu", &sectors,
2355                             "info", "%u", &binfo,
2356                             "sector-size", "%lu", &sector_size,
2357                             NULL);
2358         if (err) {
2359                 xenbus_dev_fatal(info->xbdev, err,
2360                                  "reading backend fields at %s",
2361                                  info->xbdev->otherend);
2362                 return;
2363         }
2364
2365         /*
2366          * physcial-sector-size is a newer field, so old backends may not
2367          * provide this. Assume physical sector size to be the same as
2368          * sector_size in that case.
2369          */
2370         physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2371                                                     "physical-sector-size",
2372                                                     sector_size);
2373         blkfront_gather_backend_features(info);
2374         for (i = 0; i < info->nr_rings; i++) {
2375                 err = blkfront_setup_indirect(&info->rinfo[i]);
2376                 if (err) {
2377                         xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2378                                          info->xbdev->otherend);
2379                         blkif_free(info, 0);
2380                         break;
2381                 }
2382         }
2383
2384         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2385                                   physical_sector_size);
2386         if (err) {
2387                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2388                                  info->xbdev->otherend);
2389                 goto fail;
2390         }
2391
2392         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2393
2394         /* Kick pending requests. */
2395         info->connected = BLKIF_STATE_CONNECTED;
2396         for (i = 0; i < info->nr_rings; i++)
2397                 kick_pending_request_queues(&info->rinfo[i]);
2398
2399         device_add_disk(&info->xbdev->dev, info->gd);
2400
2401         info->is_ready = 1;
2402         return;
2403
2404 fail:
2405         blkif_free(info, 0);
2406         return;
2407 }
2408
2409 /**
2410  * Callback received when the backend's state changes.
2411  */
2412 static void blkback_changed(struct xenbus_device *dev,
2413                             enum xenbus_state backend_state)
2414 {
2415         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2416
2417         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2418
2419         switch (backend_state) {
2420         case XenbusStateInitWait:
2421                 if (dev->state != XenbusStateInitialising)
2422                         break;
2423                 if (talk_to_blkback(dev, info))
2424                         break;
2425         case XenbusStateInitialising:
2426         case XenbusStateInitialised:
2427         case XenbusStateReconfiguring:
2428         case XenbusStateReconfigured:
2429         case XenbusStateUnknown:
2430                 break;
2431
2432         case XenbusStateConnected:
2433                 /*
2434                  * talk_to_blkback sets state to XenbusStateInitialised
2435                  * and blkfront_connect sets it to XenbusStateConnected
2436                  * (if connection went OK).
2437                  *
2438                  * If the backend (or toolstack) decides to poke at backend
2439                  * state (and re-trigger the watch by setting the state repeatedly
2440                  * to XenbusStateConnected (4)) we need to deal with this.
2441                  * This is allowed as this is used to communicate to the guest
2442                  * that the size of disk has changed!
2443                  */
2444                 if ((dev->state != XenbusStateInitialised) &&
2445                     (dev->state != XenbusStateConnected)) {
2446                         if (talk_to_blkback(dev, info))
2447                                 break;
2448                 }
2449
2450                 blkfront_connect(info);
2451                 break;
2452
2453         case XenbusStateClosed:
2454                 if (dev->state == XenbusStateClosed)
2455                         break;
2456                 /* Missed the backend's Closing state -- fallthrough */
2457         case XenbusStateClosing:
2458                 if (info)
2459                         blkfront_closing(info);
2460                 break;
2461         }
2462 }
2463
2464 static int blkfront_remove(struct xenbus_device *xbdev)
2465 {
2466         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2467         struct block_device *bdev = NULL;
2468         struct gendisk *disk;
2469
2470         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2471
2472         blkif_free(info, 0);
2473
2474         mutex_lock(&info->mutex);
2475
2476         disk = info->gd;
2477         if (disk)
2478                 bdev = bdget_disk(disk, 0);
2479
2480         info->xbdev = NULL;
2481         mutex_unlock(&info->mutex);
2482
2483         if (!bdev) {
2484                 kfree(info);
2485                 return 0;
2486         }
2487
2488         /*
2489          * The xbdev was removed before we reached the Closed
2490          * state. See if it's safe to remove the disk. If the bdev
2491          * isn't closed yet, we let release take care of it.
2492          */
2493
2494         mutex_lock(&bdev->bd_mutex);
2495         info = disk->private_data;
2496
2497         dev_warn(disk_to_dev(disk),
2498                  "%s was hot-unplugged, %d stale handles\n",
2499                  xbdev->nodename, bdev->bd_openers);
2500
2501         if (info && !bdev->bd_openers) {
2502                 xlvbd_release_gendisk(info);
2503                 disk->private_data = NULL;
2504                 kfree(info);
2505         }
2506
2507         mutex_unlock(&bdev->bd_mutex);
2508         bdput(bdev);
2509
2510         return 0;
2511 }
2512
2513 static int blkfront_is_ready(struct xenbus_device *dev)
2514 {
2515         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2516
2517         return info->is_ready && info->xbdev;
2518 }
2519
2520 static int blkif_open(struct block_device *bdev, fmode_t mode)
2521 {
2522         struct gendisk *disk = bdev->bd_disk;
2523         struct blkfront_info *info;
2524         int err = 0;
2525
2526         mutex_lock(&blkfront_mutex);
2527
2528         info = disk->private_data;
2529         if (!info) {
2530                 /* xbdev gone */
2531                 err = -ERESTARTSYS;
2532                 goto out;
2533         }
2534
2535         mutex_lock(&info->mutex);
2536
2537         if (!info->gd)
2538                 /* xbdev is closed */
2539                 err = -ERESTARTSYS;
2540
2541         mutex_unlock(&info->mutex);
2542
2543 out:
2544         mutex_unlock(&blkfront_mutex);
2545         return err;
2546 }
2547
2548 static void blkif_release(struct gendisk *disk, fmode_t mode)
2549 {
2550         struct blkfront_info *info = disk->private_data;
2551         struct block_device *bdev;
2552         struct xenbus_device *xbdev;
2553
2554         mutex_lock(&blkfront_mutex);
2555
2556         bdev = bdget_disk(disk, 0);
2557
2558         if (!bdev) {
2559                 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2560                 goto out_mutex;
2561         }
2562         if (bdev->bd_openers)
2563                 goto out;
2564
2565         /*
2566          * Check if we have been instructed to close. We will have
2567          * deferred this request, because the bdev was still open.
2568          */
2569
2570         mutex_lock(&info->mutex);
2571         xbdev = info->xbdev;
2572
2573         if (xbdev && xbdev->state == XenbusStateClosing) {
2574                 /* pending switch to state closed */
2575                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2576                 xlvbd_release_gendisk(info);
2577                 xenbus_frontend_closed(info->xbdev);
2578         }
2579
2580         mutex_unlock(&info->mutex);
2581
2582         if (!xbdev) {
2583                 /* sudden device removal */
2584                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2585                 xlvbd_release_gendisk(info);
2586                 disk->private_data = NULL;
2587                 kfree(info);
2588         }
2589
2590 out:
2591         bdput(bdev);
2592 out_mutex:
2593         mutex_unlock(&blkfront_mutex);
2594 }
2595
2596 static const struct block_device_operations xlvbd_block_fops =
2597 {
2598         .owner = THIS_MODULE,
2599         .open = blkif_open,
2600         .release = blkif_release,
2601         .getgeo = blkif_getgeo,
2602         .ioctl = blkif_ioctl,
2603 };
2604
2605
2606 static const struct xenbus_device_id blkfront_ids[] = {
2607         { "vbd" },
2608         { "" }
2609 };
2610
2611 static struct xenbus_driver blkfront_driver = {
2612         .ids  = blkfront_ids,
2613         .probe = blkfront_probe,
2614         .remove = blkfront_remove,
2615         .resume = blkfront_resume,
2616         .otherend_changed = blkback_changed,
2617         .is_ready = blkfront_is_ready,
2618 };
2619
2620 static int __init xlblk_init(void)
2621 {
2622         int ret;
2623         int nr_cpus = num_online_cpus();
2624
2625         if (!xen_domain())
2626                 return -ENODEV;
2627
2628         if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2629                 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2630
2631         if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2632                 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2633                         xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2634                 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2635         }
2636
2637         if (xen_blkif_max_queues > nr_cpus) {
2638                 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2639                         xen_blkif_max_queues, nr_cpus);
2640                 xen_blkif_max_queues = nr_cpus;
2641         }
2642
2643         if (!xen_has_pv_disk_devices())
2644                 return -ENODEV;
2645
2646         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2647                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2648                        XENVBD_MAJOR, DEV_NAME);
2649                 return -ENODEV;
2650         }
2651
2652         ret = xenbus_register_frontend(&blkfront_driver);
2653         if (ret) {
2654                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2655                 return ret;
2656         }
2657
2658         return 0;
2659 }
2660 module_init(xlblk_init);
2661
2662
2663 static void __exit xlblk_exit(void)
2664 {
2665         xenbus_unregister_driver(&blkfront_driver);
2666         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2667         kfree(minors);
2668 }
2669 module_exit(xlblk_exit);
2670
2671 MODULE_DESCRIPTION("Xen virtual block device frontend");
2672 MODULE_LICENSE("GPL");
2673 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2674 MODULE_ALIAS("xen:vbd");
2675 MODULE_ALIAS("xenblk");