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