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                                                           0, 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, 0, 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, 0, 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, 0);
1288                         rinfo->ring_ref[i] = GRANT_INVALID_REF;
1289                 }
1290         }
1291         free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
1292         rinfo->ring.sring = NULL;
1293
1294         if (rinfo->irq)
1295                 unbind_from_irqhandler(rinfo->irq, rinfo);
1296         rinfo->evtchn = rinfo->irq = 0;
1297 }
1298
1299 static void blkif_free(struct blkfront_info *info, int suspend)
1300 {
1301         unsigned int i;
1302         struct blkfront_ring_info *rinfo;
1303
1304         /* Prevent new requests being issued until we fix things up. */
1305         info->connected = suspend ?
1306                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1307         /* No more blkif_request(). */
1308         if (info->rq)
1309                 blk_mq_stop_hw_queues(info->rq);
1310
1311         for_each_rinfo(info, rinfo, i)
1312                 blkif_free_ring(rinfo);
1313
1314         kvfree(info->rinfo);
1315         info->rinfo = NULL;
1316         info->nr_rings = 0;
1317 }
1318
1319 struct copy_from_grant {
1320         const struct blk_shadow *s;
1321         unsigned int grant_idx;
1322         unsigned int bvec_offset;
1323         char *bvec_data;
1324 };
1325
1326 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1327                                   unsigned int len, void *data)
1328 {
1329         struct copy_from_grant *info = data;
1330         char *shared_data;
1331         /* Convenient aliases */
1332         const struct blk_shadow *s = info->s;
1333
1334         shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1335
1336         memcpy(info->bvec_data + info->bvec_offset,
1337                shared_data + offset, len);
1338
1339         info->bvec_offset += len;
1340         info->grant_idx++;
1341
1342         kunmap_atomic(shared_data);
1343 }
1344
1345 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1346 {
1347         switch (rsp)
1348         {
1349         case BLKIF_RSP_OKAY:
1350                 return REQ_DONE;
1351         case BLKIF_RSP_EOPNOTSUPP:
1352                 return REQ_EOPNOTSUPP;
1353         case BLKIF_RSP_ERROR:
1354         default:
1355                 return REQ_ERROR;
1356         }
1357 }
1358
1359 /*
1360  * Get the final status of the block request based on two ring response
1361  */
1362 static int blkif_get_final_status(enum blk_req_status s1,
1363                                   enum blk_req_status s2)
1364 {
1365         BUG_ON(s1 < REQ_DONE);
1366         BUG_ON(s2 < REQ_DONE);
1367
1368         if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1369                 return BLKIF_RSP_ERROR;
1370         else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1371                 return BLKIF_RSP_EOPNOTSUPP;
1372         return BLKIF_RSP_OKAY;
1373 }
1374
1375 static bool blkif_completion(unsigned long *id,
1376                              struct blkfront_ring_info *rinfo,
1377                              struct blkif_response *bret)
1378 {
1379         int i = 0;
1380         struct scatterlist *sg;
1381         int num_sg, num_grant;
1382         struct blkfront_info *info = rinfo->dev_info;
1383         struct blk_shadow *s = &rinfo->shadow[*id];
1384         struct copy_from_grant data = {
1385                 .grant_idx = 0,
1386         };
1387
1388         num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1389                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1390
1391         /* The I/O request may be split in two. */
1392         if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1393                 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1394
1395                 /* Keep the status of the current response in shadow. */
1396                 s->status = blkif_rsp_to_req_status(bret->status);
1397
1398                 /* Wait the second response if not yet here. */
1399                 if (s2->status < REQ_DONE)
1400                         return false;
1401
1402                 bret->status = blkif_get_final_status(s->status,
1403                                                       s2->status);
1404
1405                 /*
1406                  * All the grants is stored in the first shadow in order
1407                  * to make the completion code simpler.
1408                  */
1409                 num_grant += s2->req.u.rw.nr_segments;
1410
1411                 /*
1412                  * The two responses may not come in order. Only the
1413                  * first request will store the scatter-gather list.
1414                  */
1415                 if (s2->num_sg != 0) {
1416                         /* Update "id" with the ID of the first response. */
1417                         *id = s->associated_id;
1418                         s = s2;
1419                 }
1420
1421                 /*
1422                  * We don't need anymore the second request, so recycling
1423                  * it now.
1424                  */
1425                 if (add_id_to_freelist(rinfo, s->associated_id))
1426                         WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1427                              info->gd->disk_name, s->associated_id);
1428         }
1429
1430         data.s = s;
1431         num_sg = s->num_sg;
1432
1433         if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1434                 for_each_sg(s->sg, sg, num_sg, i) {
1435                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1436
1437                         data.bvec_offset = sg->offset;
1438                         data.bvec_data = kmap_atomic(sg_page(sg));
1439
1440                         gnttab_foreach_grant_in_range(sg_page(sg),
1441                                                       sg->offset,
1442                                                       sg->length,
1443                                                       blkif_copy_from_grant,
1444                                                       &data);
1445
1446                         kunmap_atomic(data.bvec_data);
1447                 }
1448         }
1449         /* Add the persistent grant into the list of free grants */
1450         for (i = 0; i < num_grant; i++) {
1451                 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1452                         /*
1453                          * If the grant is still mapped by the backend (the
1454                          * backend has chosen to make this grant persistent)
1455                          * we add it at the head of the list, so it will be
1456                          * reused first.
1457                          */
1458                         if (!info->feature_persistent)
1459                                 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1460                                                      s->grants_used[i]->gref);
1461                         list_add(&s->grants_used[i]->node, &rinfo->grants);
1462                         rinfo->persistent_gnts_c++;
1463                 } else {
1464                         /*
1465                          * If the grant is not mapped by the backend we end the
1466                          * foreign access and add it to the tail of the list,
1467                          * so it will not be picked again unless we run out of
1468                          * persistent grants.
1469                          */
1470                         gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1471                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1472                         list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1473                 }
1474         }
1475         if (s->req.operation == BLKIF_OP_INDIRECT) {
1476                 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1477                         if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1478                                 if (!info->feature_persistent)
1479                                         pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1480                                                              s->indirect_grants[i]->gref);
1481                                 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1482                                 rinfo->persistent_gnts_c++;
1483                         } else {
1484                                 struct page *indirect_page;
1485
1486                                 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1487                                 /*
1488                                  * Add the used indirect page back to the list of
1489                                  * available pages for indirect grefs.
1490                                  */
1491                                 if (!info->feature_persistent) {
1492                                         indirect_page = s->indirect_grants[i]->page;
1493                                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
1494                                 }
1495                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1496                                 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1497                         }
1498                 }
1499         }
1500
1501         return true;
1502 }
1503
1504 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1505 {
1506         struct request *req;
1507         struct blkif_response bret;
1508         RING_IDX i, rp;
1509         unsigned long flags;
1510         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1511         struct blkfront_info *info = rinfo->dev_info;
1512         unsigned int eoiflag = XEN_EOI_FLAG_SPURIOUS;
1513
1514         if (unlikely(info->connected != BLKIF_STATE_CONNECTED)) {
1515                 xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
1516                 return IRQ_HANDLED;
1517         }
1518
1519         spin_lock_irqsave(&rinfo->ring_lock, flags);
1520  again:
1521         rp = READ_ONCE(rinfo->ring.sring->rsp_prod);
1522         virt_rmb(); /* Ensure we see queued responses up to 'rp'. */
1523         if (RING_RESPONSE_PROD_OVERFLOW(&rinfo->ring, rp)) {
1524                 pr_alert("%s: illegal number of responses %u\n",
1525                          info->gd->disk_name, rp - rinfo->ring.rsp_cons);
1526                 goto err;
1527         }
1528
1529         for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1530                 unsigned long id;
1531                 unsigned int op;
1532
1533                 eoiflag = 0;
1534
1535                 RING_COPY_RESPONSE(&rinfo->ring, i, &bret);
1536                 id = bret.id;
1537
1538                 /*
1539                  * The backend has messed up and given us an id that we would
1540                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1541                  * look in get_id_from_freelist.
1542                  */
1543                 if (id >= BLK_RING_SIZE(info)) {
1544                         pr_alert("%s: response has incorrect id (%ld)\n",
1545                                  info->gd->disk_name, id);
1546                         goto err;
1547                 }
1548                 if (rinfo->shadow[id].status != REQ_WAITING) {
1549                         pr_alert("%s: response references no pending request\n",
1550                                  info->gd->disk_name);
1551                         goto err;
1552                 }
1553
1554                 rinfo->shadow[id].status = REQ_PROCESSING;
1555                 req  = rinfo->shadow[id].request;
1556
1557                 op = rinfo->shadow[id].req.operation;
1558                 if (op == BLKIF_OP_INDIRECT)
1559                         op = rinfo->shadow[id].req.u.indirect.indirect_op;
1560                 if (bret.operation != op) {
1561                         pr_alert("%s: response has wrong operation (%u instead of %u)\n",
1562                                  info->gd->disk_name, bret.operation, op);
1563                         goto err;
1564                 }
1565
1566                 if (bret.operation != BLKIF_OP_DISCARD) {
1567                         /*
1568                          * We may need to wait for an extra response if the
1569                          * I/O request is split in 2
1570                          */
1571                         if (!blkif_completion(&id, rinfo, &bret))
1572                                 continue;
1573                 }
1574
1575                 if (add_id_to_freelist(rinfo, id)) {
1576                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1577                              info->gd->disk_name, op_name(bret.operation), id);
1578                         continue;
1579                 }
1580
1581                 if (bret.status == BLKIF_RSP_OKAY)
1582                         blkif_req(req)->error = BLK_STS_OK;
1583                 else
1584                         blkif_req(req)->error = BLK_STS_IOERR;
1585
1586                 switch (bret.operation) {
1587                 case BLKIF_OP_DISCARD:
1588                         if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1589                                 struct request_queue *rq = info->rq;
1590
1591                                 pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1592                                            info->gd->disk_name, op_name(bret.operation));
1593                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1594                                 info->feature_discard = 0;
1595                                 info->feature_secdiscard = 0;
1596                                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1597                                 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1598                         }
1599                         break;
1600                 case BLKIF_OP_FLUSH_DISKCACHE:
1601                 case BLKIF_OP_WRITE_BARRIER:
1602                         if (unlikely(bret.status == BLKIF_RSP_EOPNOTSUPP)) {
1603                                 pr_warn_ratelimited("blkfront: %s: %s op failed\n",
1604                                        info->gd->disk_name, op_name(bret.operation));
1605                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1606                         }
1607                         if (unlikely(bret.status == BLKIF_RSP_ERROR &&
1608                                      rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1609                                 pr_warn_ratelimited("blkfront: %s: empty %s op failed\n",
1610                                        info->gd->disk_name, op_name(bret.operation));
1611                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1612                         }
1613                         if (unlikely(blkif_req(req)->error)) {
1614                                 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1615                                         blkif_req(req)->error = BLK_STS_OK;
1616                                 info->feature_fua = 0;
1617                                 info->feature_flush = 0;
1618                                 xlvbd_flush(info);
1619                         }
1620                         fallthrough;
1621                 case BLKIF_OP_READ:
1622                 case BLKIF_OP_WRITE:
1623                         if (unlikely(bret.status != BLKIF_RSP_OKAY))
1624                                 dev_dbg_ratelimited(&info->xbdev->dev,
1625                                         "Bad return from blkdev data request: %#x\n",
1626                                         bret.status);
1627
1628                         break;
1629                 default:
1630                         BUG();
1631                 }
1632
1633                 if (likely(!blk_should_fake_timeout(req->q)))
1634                         blk_mq_complete_request(req);
1635         }
1636
1637         rinfo->ring.rsp_cons = i;
1638
1639         if (i != rinfo->ring.req_prod_pvt) {
1640                 int more_to_do;
1641                 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1642                 if (more_to_do)
1643                         goto again;
1644         } else
1645                 rinfo->ring.sring->rsp_event = i + 1;
1646
1647         kick_pending_request_queues_locked(rinfo);
1648
1649         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1650
1651         xen_irq_lateeoi(irq, eoiflag);
1652
1653         return IRQ_HANDLED;
1654
1655  err:
1656         info->connected = BLKIF_STATE_ERROR;
1657
1658         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1659
1660         /* No EOI in order to avoid further interrupts. */
1661
1662         pr_alert("%s disabled for further use\n", info->gd->disk_name);
1663         return IRQ_HANDLED;
1664 }
1665
1666
1667 static int setup_blkring(struct xenbus_device *dev,
1668                          struct blkfront_ring_info *rinfo)
1669 {
1670         struct blkif_sring *sring;
1671         int err, i;
1672         struct blkfront_info *info = rinfo->dev_info;
1673         unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1674         grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1675
1676         for (i = 0; i < info->nr_ring_pages; i++)
1677                 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1678
1679         sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1680                                                        get_order(ring_size));
1681         if (!sring) {
1682                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1683                 return -ENOMEM;
1684         }
1685         SHARED_RING_INIT(sring);
1686         FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1687
1688         err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1689         if (err < 0) {
1690                 free_pages((unsigned long)sring, get_order(ring_size));
1691                 rinfo->ring.sring = NULL;
1692                 goto fail;
1693         }
1694         for (i = 0; i < info->nr_ring_pages; i++)
1695                 rinfo->ring_ref[i] = gref[i];
1696
1697         err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1698         if (err)
1699                 goto fail;
1700
1701         err = bind_evtchn_to_irqhandler_lateeoi(rinfo->evtchn, blkif_interrupt,
1702                                                 0, "blkif", rinfo);
1703         if (err <= 0) {
1704                 xenbus_dev_fatal(dev, err,
1705                                  "bind_evtchn_to_irqhandler failed");
1706                 goto fail;
1707         }
1708         rinfo->irq = err;
1709
1710         return 0;
1711 fail:
1712         blkif_free(info, 0);
1713         return err;
1714 }
1715
1716 /*
1717  * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1718  * ring buffer may have multi pages depending on ->nr_ring_pages.
1719  */
1720 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1721                                 struct blkfront_ring_info *rinfo, const char *dir)
1722 {
1723         int err;
1724         unsigned int i;
1725         const char *message = NULL;
1726         struct blkfront_info *info = rinfo->dev_info;
1727
1728         if (info->nr_ring_pages == 1) {
1729                 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1730                 if (err) {
1731                         message = "writing ring-ref";
1732                         goto abort_transaction;
1733                 }
1734         } else {
1735                 for (i = 0; i < info->nr_ring_pages; i++) {
1736                         char ring_ref_name[RINGREF_NAME_LEN];
1737
1738                         snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1739                         err = xenbus_printf(xbt, dir, ring_ref_name,
1740                                             "%u", rinfo->ring_ref[i]);
1741                         if (err) {
1742                                 message = "writing ring-ref";
1743                                 goto abort_transaction;
1744                         }
1745                 }
1746         }
1747
1748         err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1749         if (err) {
1750                 message = "writing event-channel";
1751                 goto abort_transaction;
1752         }
1753
1754         return 0;
1755
1756 abort_transaction:
1757         xenbus_transaction_end(xbt, 1);
1758         if (message)
1759                 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1760
1761         return err;
1762 }
1763
1764 /* Common code used when first setting up, and when resuming. */
1765 static int talk_to_blkback(struct xenbus_device *dev,
1766                            struct blkfront_info *info)
1767 {
1768         const char *message = NULL;
1769         struct xenbus_transaction xbt;
1770         int err;
1771         unsigned int i, max_page_order;
1772         unsigned int ring_page_order;
1773         struct blkfront_ring_info *rinfo;
1774
1775         if (!info)
1776                 return -ENODEV;
1777
1778         max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1779                                               "max-ring-page-order", 0);
1780         ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1781         info->nr_ring_pages = 1 << ring_page_order;
1782
1783         err = negotiate_mq(info);
1784         if (err)
1785                 goto destroy_blkring;
1786
1787         for_each_rinfo(info, rinfo, i) {
1788                 /* Create shared ring, alloc event channel. */
1789                 err = setup_blkring(dev, rinfo);
1790                 if (err)
1791                         goto destroy_blkring;
1792         }
1793
1794 again:
1795         err = xenbus_transaction_start(&xbt);
1796         if (err) {
1797                 xenbus_dev_fatal(dev, err, "starting transaction");
1798                 goto destroy_blkring;
1799         }
1800
1801         if (info->nr_ring_pages > 1) {
1802                 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1803                                     ring_page_order);
1804                 if (err) {
1805                         message = "writing ring-page-order";
1806                         goto abort_transaction;
1807                 }
1808         }
1809
1810         /* We already got the number of queues/rings in _probe */
1811         if (info->nr_rings == 1) {
1812                 err = write_per_ring_nodes(xbt, info->rinfo, dev->nodename);
1813                 if (err)
1814                         goto destroy_blkring;
1815         } else {
1816                 char *path;
1817                 size_t pathsize;
1818
1819                 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1820                                     info->nr_rings);
1821                 if (err) {
1822                         message = "writing multi-queue-num-queues";
1823                         goto abort_transaction;
1824                 }
1825
1826                 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1827                 path = kmalloc(pathsize, GFP_KERNEL);
1828                 if (!path) {
1829                         err = -ENOMEM;
1830                         message = "ENOMEM while writing ring references";
1831                         goto abort_transaction;
1832                 }
1833
1834                 for_each_rinfo(info, rinfo, i) {
1835                         memset(path, 0, pathsize);
1836                         snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1837                         err = write_per_ring_nodes(xbt, rinfo, path);
1838                         if (err) {
1839                                 kfree(path);
1840                                 goto destroy_blkring;
1841                         }
1842                 }
1843                 kfree(path);
1844         }
1845         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1846                             XEN_IO_PROTO_ABI_NATIVE);
1847         if (err) {
1848                 message = "writing protocol";
1849                 goto abort_transaction;
1850         }
1851         err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
1852                         info->feature_persistent);
1853         if (err)
1854                 dev_warn(&dev->dev,
1855                          "writing persistent grants feature to xenbus");
1856
1857         err = xenbus_transaction_end(xbt, 0);
1858         if (err) {
1859                 if (err == -EAGAIN)
1860                         goto again;
1861                 xenbus_dev_fatal(dev, err, "completing transaction");
1862                 goto destroy_blkring;
1863         }
1864
1865         for_each_rinfo(info, rinfo, i) {
1866                 unsigned int j;
1867
1868                 for (j = 0; j < BLK_RING_SIZE(info); j++)
1869                         rinfo->shadow[j].req.u.rw.id = j + 1;
1870                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1871         }
1872         xenbus_switch_state(dev, XenbusStateInitialised);
1873
1874         return 0;
1875
1876  abort_transaction:
1877         xenbus_transaction_end(xbt, 1);
1878         if (message)
1879                 xenbus_dev_fatal(dev, err, "%s", message);
1880  destroy_blkring:
1881         blkif_free(info, 0);
1882         return err;
1883 }
1884
1885 static int negotiate_mq(struct blkfront_info *info)
1886 {
1887         unsigned int backend_max_queues;
1888         unsigned int i;
1889         struct blkfront_ring_info *rinfo;
1890
1891         BUG_ON(info->nr_rings);
1892
1893         /* Check if backend supports multiple queues. */
1894         backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1895                                                   "multi-queue-max-queues", 1);
1896         info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1897         /* We need at least one ring. */
1898         if (!info->nr_rings)
1899                 info->nr_rings = 1;
1900
1901         info->rinfo_size = struct_size(info->rinfo, shadow,
1902                                        BLK_RING_SIZE(info));
1903         info->rinfo = kvcalloc(info->nr_rings, info->rinfo_size, GFP_KERNEL);
1904         if (!info->rinfo) {
1905                 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1906                 info->nr_rings = 0;
1907                 return -ENOMEM;
1908         }
1909
1910         for_each_rinfo(info, rinfo, i) {
1911                 INIT_LIST_HEAD(&rinfo->indirect_pages);
1912                 INIT_LIST_HEAD(&rinfo->grants);
1913                 rinfo->dev_info = info;
1914                 INIT_WORK(&rinfo->work, blkif_restart_queue);
1915                 spin_lock_init(&rinfo->ring_lock);
1916         }
1917         return 0;
1918 }
1919
1920 /* Enable the persistent grants feature. */
1921 static bool feature_persistent = true;
1922 module_param(feature_persistent, bool, 0644);
1923 MODULE_PARM_DESC(feature_persistent,
1924                 "Enables the persistent grants feature");
1925
1926 /*
1927  * Entry point to this code when a new device is created.  Allocate the basic
1928  * structures and the ring buffer for communication with the backend, and
1929  * inform the backend of the appropriate details for those.  Switch to
1930  * Initialised state.
1931  */
1932 static int blkfront_probe(struct xenbus_device *dev,
1933                           const struct xenbus_device_id *id)
1934 {
1935         int err, vdevice;
1936         struct blkfront_info *info;
1937
1938         /* FIXME: Use dynamic device id if this is not set. */
1939         err = xenbus_scanf(XBT_NIL, dev->nodename,
1940                            "virtual-device", "%i", &vdevice);
1941         if (err != 1) {
1942                 /* go looking in the extended area instead */
1943                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1944                                    "%i", &vdevice);
1945                 if (err != 1) {
1946                         xenbus_dev_fatal(dev, err, "reading virtual-device");
1947                         return err;
1948                 }
1949         }
1950
1951         if (xen_hvm_domain()) {
1952                 char *type;
1953                 int len;
1954                 /* no unplug has been done: do not hook devices != xen vbds */
1955                 if (xen_has_pv_and_legacy_disk_devices()) {
1956                         int major;
1957
1958                         if (!VDEV_IS_EXTENDED(vdevice))
1959                                 major = BLKIF_MAJOR(vdevice);
1960                         else
1961                                 major = XENVBD_MAJOR;
1962
1963                         if (major != XENVBD_MAJOR) {
1964                                 printk(KERN_INFO
1965                                                 "%s: HVM does not support vbd %d as xen block device\n",
1966                                                 __func__, vdevice);
1967                                 return -ENODEV;
1968                         }
1969                 }
1970                 /* do not create a PV cdrom device if we are an HVM guest */
1971                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1972                 if (IS_ERR(type))
1973                         return -ENODEV;
1974                 if (strncmp(type, "cdrom", 5) == 0) {
1975                         kfree(type);
1976                         return -ENODEV;
1977                 }
1978                 kfree(type);
1979         }
1980         info = kzalloc(sizeof(*info), GFP_KERNEL);
1981         if (!info) {
1982                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1983                 return -ENOMEM;
1984         }
1985
1986         info->xbdev = dev;
1987
1988         mutex_init(&info->mutex);
1989         info->vdevice = vdevice;
1990         info->connected = BLKIF_STATE_DISCONNECTED;
1991
1992         info->feature_persistent = feature_persistent;
1993
1994         /* Front end dir is a number, which is used as the id. */
1995         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1996         dev_set_drvdata(&dev->dev, info);
1997
1998         mutex_lock(&blkfront_mutex);
1999         list_add(&info->info_list, &info_list);
2000         mutex_unlock(&blkfront_mutex);
2001
2002         return 0;
2003 }
2004
2005 static int blkif_recover(struct blkfront_info *info)
2006 {
2007         unsigned int r_index;
2008         struct request *req, *n;
2009         int rc;
2010         struct bio *bio;
2011         unsigned int segs;
2012         struct blkfront_ring_info *rinfo;
2013
2014         blkfront_gather_backend_features(info);
2015         /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2016         blkif_set_queue_limits(info);
2017         segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2018         blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2019
2020         for_each_rinfo(info, rinfo, r_index) {
2021                 rc = blkfront_setup_indirect(rinfo);
2022                 if (rc)
2023                         return rc;
2024         }
2025         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2026
2027         /* Now safe for us to use the shared ring */
2028         info->connected = BLKIF_STATE_CONNECTED;
2029
2030         for_each_rinfo(info, rinfo, r_index) {
2031                 /* Kick any other new requests queued since we resumed */
2032                 kick_pending_request_queues(rinfo);
2033         }
2034
2035         list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2036                 /* Requeue pending requests (flush or discard) */
2037                 list_del_init(&req->queuelist);
2038                 BUG_ON(req->nr_phys_segments > segs);
2039                 blk_mq_requeue_request(req, false);
2040         }
2041         blk_mq_start_stopped_hw_queues(info->rq, true);
2042         blk_mq_kick_requeue_list(info->rq);
2043
2044         while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2045                 /* Traverse the list of pending bios and re-queue them */
2046                 submit_bio(bio);
2047         }
2048
2049         return 0;
2050 }
2051
2052 /*
2053  * We are reconnecting to the backend, due to a suspend/resume, or a backend
2054  * driver restart.  We tear down our blkif structure and recreate it, but
2055  * leave the device-layer structures intact so that this is transparent to the
2056  * rest of the kernel.
2057  */
2058 static int blkfront_resume(struct xenbus_device *dev)
2059 {
2060         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2061         int err = 0;
2062         unsigned int i, j;
2063         struct blkfront_ring_info *rinfo;
2064
2065         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2066
2067         bio_list_init(&info->bio_list);
2068         INIT_LIST_HEAD(&info->requests);
2069         for_each_rinfo(info, rinfo, i) {
2070                 struct bio_list merge_bio;
2071                 struct blk_shadow *shadow = rinfo->shadow;
2072
2073                 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2074                         /* Not in use? */
2075                         if (!shadow[j].request)
2076                                 continue;
2077
2078                         /*
2079                          * Get the bios in the request so we can re-queue them.
2080                          */
2081                         if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2082                             req_op(shadow[j].request) == REQ_OP_DISCARD ||
2083                             req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2084                             shadow[j].request->cmd_flags & REQ_FUA) {
2085                                 /*
2086                                  * Flush operations don't contain bios, so
2087                                  * we need to requeue the whole request
2088                                  *
2089                                  * XXX: but this doesn't make any sense for a
2090                                  * write with the FUA flag set..
2091                                  */
2092                                 list_add(&shadow[j].request->queuelist, &info->requests);
2093                                 continue;
2094                         }
2095                         merge_bio.head = shadow[j].request->bio;
2096                         merge_bio.tail = shadow[j].request->biotail;
2097                         bio_list_merge(&info->bio_list, &merge_bio);
2098                         shadow[j].request->bio = NULL;
2099                         blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2100                 }
2101         }
2102
2103         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2104
2105         err = talk_to_blkback(dev, info);
2106         if (!err)
2107                 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2108
2109         /*
2110          * We have to wait for the backend to switch to
2111          * connected state, since we want to read which
2112          * features it supports.
2113          */
2114
2115         return err;
2116 }
2117
2118 static void blkfront_closing(struct blkfront_info *info)
2119 {
2120         struct xenbus_device *xbdev = info->xbdev;
2121         struct blkfront_ring_info *rinfo;
2122         unsigned int i;
2123
2124         if (xbdev->state == XenbusStateClosing)
2125                 return;
2126
2127         /* No more blkif_request(). */
2128         blk_mq_stop_hw_queues(info->rq);
2129         blk_mark_disk_dead(info->gd);
2130         set_capacity(info->gd, 0);
2131
2132         for_each_rinfo(info, rinfo, i) {
2133                 /* No more gnttab callback work. */
2134                 gnttab_cancel_free_callback(&rinfo->callback);
2135
2136                 /* Flush gnttab callback work. Must be done with no locks held. */
2137                 flush_work(&rinfo->work);
2138         }
2139
2140         xenbus_frontend_closed(xbdev);
2141 }
2142
2143 static void blkfront_setup_discard(struct blkfront_info *info)
2144 {
2145         info->feature_discard = 1;
2146         info->discard_granularity = xenbus_read_unsigned(info->xbdev->otherend,
2147                                                          "discard-granularity",
2148                                                          0);
2149         info->discard_alignment = xenbus_read_unsigned(info->xbdev->otherend,
2150                                                        "discard-alignment", 0);
2151         info->feature_secdiscard =
2152                 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2153                                        0);
2154 }
2155
2156 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2157 {
2158         unsigned int psegs, grants, memflags;
2159         int err, i;
2160         struct blkfront_info *info = rinfo->dev_info;
2161
2162         memflags = memalloc_noio_save();
2163
2164         if (info->max_indirect_segments == 0) {
2165                 if (!HAS_EXTRA_REQ)
2166                         grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2167                 else {
2168                         /*
2169                          * When an extra req is required, the maximum
2170                          * grants supported is related to the size of the
2171                          * Linux block segment.
2172                          */
2173                         grants = GRANTS_PER_PSEG;
2174                 }
2175         }
2176         else
2177                 grants = info->max_indirect_segments;
2178         psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2179
2180         err = fill_grant_buffer(rinfo,
2181                                 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2182         if (err)
2183                 goto out_of_memory;
2184
2185         if (!info->feature_persistent && info->max_indirect_segments) {
2186                 /*
2187                  * We are using indirect descriptors but not persistent
2188                  * grants, we need to allocate a set of pages that can be
2189                  * used for mapping indirect grefs
2190                  */
2191                 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2192
2193                 BUG_ON(!list_empty(&rinfo->indirect_pages));
2194                 for (i = 0; i < num; i++) {
2195                         struct page *indirect_page = alloc_page(GFP_KERNEL);
2196                         if (!indirect_page)
2197                                 goto out_of_memory;
2198                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
2199                 }
2200         }
2201
2202         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2203                 rinfo->shadow[i].grants_used =
2204                         kvcalloc(grants,
2205                                  sizeof(rinfo->shadow[i].grants_used[0]),
2206                                  GFP_KERNEL);
2207                 rinfo->shadow[i].sg = kvcalloc(psegs,
2208                                                sizeof(rinfo->shadow[i].sg[0]),
2209                                                GFP_KERNEL);
2210                 if (info->max_indirect_segments)
2211                         rinfo->shadow[i].indirect_grants =
2212                                 kvcalloc(INDIRECT_GREFS(grants),
2213                                          sizeof(rinfo->shadow[i].indirect_grants[0]),
2214                                          GFP_KERNEL);
2215                 if ((rinfo->shadow[i].grants_used == NULL) ||
2216                         (rinfo->shadow[i].sg == NULL) ||
2217                      (info->max_indirect_segments &&
2218                      (rinfo->shadow[i].indirect_grants == NULL)))
2219                         goto out_of_memory;
2220                 sg_init_table(rinfo->shadow[i].sg, psegs);
2221         }
2222
2223         memalloc_noio_restore(memflags);
2224
2225         return 0;
2226
2227 out_of_memory:
2228         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2229                 kvfree(rinfo->shadow[i].grants_used);
2230                 rinfo->shadow[i].grants_used = NULL;
2231                 kvfree(rinfo->shadow[i].sg);
2232                 rinfo->shadow[i].sg = NULL;
2233                 kvfree(rinfo->shadow[i].indirect_grants);
2234                 rinfo->shadow[i].indirect_grants = NULL;
2235         }
2236         if (!list_empty(&rinfo->indirect_pages)) {
2237                 struct page *indirect_page, *n;
2238                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2239                         list_del(&indirect_page->lru);
2240                         __free_page(indirect_page);
2241                 }
2242         }
2243
2244         memalloc_noio_restore(memflags);
2245
2246         return -ENOMEM;
2247 }
2248
2249 /*
2250  * Gather all backend feature-*
2251  */
2252 static void blkfront_gather_backend_features(struct blkfront_info *info)
2253 {
2254         unsigned int indirect_segments;
2255
2256         info->feature_flush = 0;
2257         info->feature_fua = 0;
2258
2259         /*
2260          * If there's no "feature-barrier" defined, then it means
2261          * we're dealing with a very old backend which writes
2262          * synchronously; nothing to do.
2263          *
2264          * If there are barriers, then we use flush.
2265          */
2266         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2267                 info->feature_flush = 1;
2268                 info->feature_fua = 1;
2269         }
2270
2271         /*
2272          * And if there is "feature-flush-cache" use that above
2273          * barriers.
2274          */
2275         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2276                                  0)) {
2277                 info->feature_flush = 1;
2278                 info->feature_fua = 0;
2279         }
2280
2281         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2282                 blkfront_setup_discard(info);
2283
2284         if (info->feature_persistent)
2285                 info->feature_persistent =
2286                         !!xenbus_read_unsigned(info->xbdev->otherend,
2287                                                "feature-persistent", 0);
2288
2289         indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2290                                         "feature-max-indirect-segments", 0);
2291         if (indirect_segments > xen_blkif_max_segments)
2292                 indirect_segments = xen_blkif_max_segments;
2293         if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2294                 indirect_segments = 0;
2295         info->max_indirect_segments = indirect_segments;
2296
2297         if (info->feature_persistent) {
2298                 mutex_lock(&blkfront_mutex);
2299                 schedule_delayed_work(&blkfront_work, HZ * 10);
2300                 mutex_unlock(&blkfront_mutex);
2301         }
2302 }
2303
2304 /*
2305  * Invoked when the backend is finally 'ready' (and has told produced
2306  * the details about the physical device - #sectors, size, etc).
2307  */
2308 static void blkfront_connect(struct blkfront_info *info)
2309 {
2310         unsigned long long sectors;
2311         unsigned long sector_size;
2312         unsigned int physical_sector_size;
2313         int err, i;
2314         struct blkfront_ring_info *rinfo;
2315
2316         switch (info->connected) {
2317         case BLKIF_STATE_CONNECTED:
2318                 /*
2319                  * Potentially, the back-end may be signalling
2320                  * a capacity change; update the capacity.
2321                  */
2322                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2323                                    "sectors", "%Lu", &sectors);
2324                 if (XENBUS_EXIST_ERR(err))
2325                         return;
2326                 printk(KERN_INFO "Setting capacity to %Lu\n",
2327                        sectors);
2328                 set_capacity_and_notify(info->gd, sectors);
2329
2330                 return;
2331         case BLKIF_STATE_SUSPENDED:
2332                 /*
2333                  * If we are recovering from suspension, we need to wait
2334                  * for the backend to announce it's features before
2335                  * reconnecting, at least we need to know if the backend
2336                  * supports indirect descriptors, and how many.
2337                  */
2338                 blkif_recover(info);
2339                 return;
2340
2341         default:
2342                 break;
2343         }
2344
2345         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2346                 __func__, info->xbdev->otherend);
2347
2348         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2349                             "sectors", "%llu", &sectors,
2350                             "info", "%u", &info->vdisk_info,
2351                             "sector-size", "%lu", &sector_size,
2352                             NULL);
2353         if (err) {
2354                 xenbus_dev_fatal(info->xbdev, err,
2355                                  "reading backend fields at %s",
2356                                  info->xbdev->otherend);
2357                 return;
2358         }
2359
2360         /*
2361          * physical-sector-size is a newer field, so old backends may not
2362          * provide this. Assume physical sector size to be the same as
2363          * sector_size in that case.
2364          */
2365         physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2366                                                     "physical-sector-size",
2367                                                     sector_size);
2368         blkfront_gather_backend_features(info);
2369         for_each_rinfo(info, rinfo, i) {
2370                 err = blkfront_setup_indirect(rinfo);
2371                 if (err) {
2372                         xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2373                                          info->xbdev->otherend);
2374                         blkif_free(info, 0);
2375                         break;
2376                 }
2377         }
2378
2379         err = xlvbd_alloc_gendisk(sectors, info, sector_size,
2380                                   physical_sector_size);
2381         if (err) {
2382                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2383                                  info->xbdev->otherend);
2384                 goto fail;
2385         }
2386
2387         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2388
2389         /* Kick pending requests. */
2390         info->connected = BLKIF_STATE_CONNECTED;
2391         for_each_rinfo(info, rinfo, i)
2392                 kick_pending_request_queues(rinfo);
2393
2394         err = device_add_disk(&info->xbdev->dev, info->gd, NULL);
2395         if (err) {
2396                 blk_cleanup_disk(info->gd);
2397                 blk_mq_free_tag_set(&info->tag_set);
2398                 info->rq = NULL;
2399                 goto fail;
2400         }
2401
2402         info->is_ready = 1;
2403         return;
2404
2405 fail:
2406         blkif_free(info, 0);
2407         return;
2408 }
2409
2410 /*
2411  * Callback received when the backend's state changes.
2412  */
2413 static void blkback_changed(struct xenbus_device *dev,
2414                             enum xenbus_state backend_state)
2415 {
2416         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2417
2418         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2419
2420         switch (backend_state) {
2421         case XenbusStateInitWait:
2422                 if (dev->state != XenbusStateInitialising)
2423                         break;
2424                 if (talk_to_blkback(dev, info))
2425                         break;
2426                 break;
2427         case XenbusStateInitialising:
2428         case XenbusStateInitialised:
2429         case XenbusStateReconfiguring:
2430         case XenbusStateReconfigured:
2431         case XenbusStateUnknown:
2432                 break;
2433
2434         case XenbusStateConnected:
2435                 /*
2436                  * talk_to_blkback sets state to XenbusStateInitialised
2437                  * and blkfront_connect sets it to XenbusStateConnected
2438                  * (if connection went OK).
2439                  *
2440                  * If the backend (or toolstack) decides to poke at backend
2441                  * state (and re-trigger the watch by setting the state repeatedly
2442                  * to XenbusStateConnected (4)) we need to deal with this.
2443                  * This is allowed as this is used to communicate to the guest
2444                  * that the size of disk has changed!
2445                  */
2446                 if ((dev->state != XenbusStateInitialised) &&
2447                     (dev->state != XenbusStateConnected)) {
2448                         if (talk_to_blkback(dev, info))
2449                                 break;
2450                 }
2451
2452                 blkfront_connect(info);
2453                 break;
2454
2455         case XenbusStateClosed:
2456                 if (dev->state == XenbusStateClosed)
2457                         break;
2458                 fallthrough;
2459         case XenbusStateClosing:
2460                 blkfront_closing(info);
2461                 break;
2462         }
2463 }
2464
2465 static int blkfront_remove(struct xenbus_device *xbdev)
2466 {
2467         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2468
2469         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2470
2471         del_gendisk(info->gd);
2472
2473         mutex_lock(&blkfront_mutex);
2474         list_del(&info->info_list);
2475         mutex_unlock(&blkfront_mutex);
2476
2477         blkif_free(info, 0);
2478         xlbd_release_minors(info->gd->first_minor, info->gd->minors);
2479         blk_cleanup_disk(info->gd);
2480         blk_mq_free_tag_set(&info->tag_set);
2481
2482         kfree(info);
2483         return 0;
2484 }
2485
2486 static int blkfront_is_ready(struct xenbus_device *dev)
2487 {
2488         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2489
2490         return info->is_ready && info->xbdev;
2491 }
2492
2493 static const struct block_device_operations xlvbd_block_fops =
2494 {
2495         .owner = THIS_MODULE,
2496         .getgeo = blkif_getgeo,
2497         .ioctl = blkif_ioctl,
2498         .compat_ioctl = blkdev_compat_ptr_ioctl,
2499 };
2500
2501
2502 static const struct xenbus_device_id blkfront_ids[] = {
2503         { "vbd" },
2504         { "" }
2505 };
2506
2507 static struct xenbus_driver blkfront_driver = {
2508         .ids  = blkfront_ids,
2509         .probe = blkfront_probe,
2510         .remove = blkfront_remove,
2511         .resume = blkfront_resume,
2512         .otherend_changed = blkback_changed,
2513         .is_ready = blkfront_is_ready,
2514 };
2515
2516 static void purge_persistent_grants(struct blkfront_info *info)
2517 {
2518         unsigned int i;
2519         unsigned long flags;
2520         struct blkfront_ring_info *rinfo;
2521
2522         for_each_rinfo(info, rinfo, i) {
2523                 struct grant *gnt_list_entry, *tmp;
2524
2525                 spin_lock_irqsave(&rinfo->ring_lock, flags);
2526
2527                 if (rinfo->persistent_gnts_c == 0) {
2528                         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2529                         continue;
2530                 }
2531
2532                 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2533                                          node) {
2534                         if (gnt_list_entry->gref == GRANT_INVALID_REF ||
2535                             gnttab_query_foreign_access(gnt_list_entry->gref))
2536                                 continue;
2537
2538                         list_del(&gnt_list_entry->node);
2539                         gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL);
2540                         rinfo->persistent_gnts_c--;
2541                         gnt_list_entry->gref = GRANT_INVALID_REF;
2542                         list_add_tail(&gnt_list_entry->node, &rinfo->grants);
2543                 }
2544
2545                 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2546         }
2547 }
2548
2549 static void blkfront_delay_work(struct work_struct *work)
2550 {
2551         struct blkfront_info *info;
2552         bool need_schedule_work = false;
2553
2554         mutex_lock(&blkfront_mutex);
2555
2556         list_for_each_entry(info, &info_list, info_list) {
2557                 if (info->feature_persistent) {
2558                         need_schedule_work = true;
2559                         mutex_lock(&info->mutex);
2560                         purge_persistent_grants(info);
2561                         mutex_unlock(&info->mutex);
2562                 }
2563         }
2564
2565         if (need_schedule_work)
2566                 schedule_delayed_work(&blkfront_work, HZ * 10);
2567
2568         mutex_unlock(&blkfront_mutex);
2569 }
2570
2571 static int __init xlblk_init(void)
2572 {
2573         int ret;
2574         int nr_cpus = num_online_cpus();
2575
2576         if (!xen_domain())
2577                 return -ENODEV;
2578
2579         if (!xen_has_pv_disk_devices())
2580                 return -ENODEV;
2581
2582         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2583                 pr_warn("xen_blk: can't get major %d with name %s\n",
2584                         XENVBD_MAJOR, DEV_NAME);
2585                 return -ENODEV;
2586         }
2587
2588         if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2589                 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2590
2591         if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2592                 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2593                         xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2594                 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2595         }
2596
2597         if (xen_blkif_max_queues > nr_cpus) {
2598                 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2599                         xen_blkif_max_queues, nr_cpus);
2600                 xen_blkif_max_queues = nr_cpus;
2601         }
2602
2603         INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2604
2605         ret = xenbus_register_frontend(&blkfront_driver);
2606         if (ret) {
2607                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2608                 return ret;
2609         }
2610
2611         return 0;
2612 }
2613 module_init(xlblk_init);
2614
2615
2616 static void __exit xlblk_exit(void)
2617 {
2618         cancel_delayed_work_sync(&blkfront_work);
2619
2620         xenbus_unregister_driver(&blkfront_driver);
2621         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2622         kfree(minors);
2623 }
2624 module_exit(xlblk_exit);
2625
2626 MODULE_DESCRIPTION("Xen virtual block device frontend");
2627 MODULE_LICENSE("GPL");
2628 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2629 MODULE_ALIAS("xen:vbd");
2630 MODULE_ALIAS("xenblk");