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