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