drivers/block/xen-blkfront.c

   1 /*
   2  * blkfront.c
   3  *
   4  * XenLinux virtual block device driver.
   5  *
   6  * Copyright (c) 2003-2004, Keir Fraser & Steve Hand
   7  * Modifications by Mark A. Williamson are (c) Intel Research Cambridge
   8  * Copyright (c) 2004, Christian Limpach
   9  * Copyright (c) 2004, Andrew Warfield
  10  * Copyright (c) 2005, Christopher Clark
  11  * Copyright (c) 2005, XenSource Ltd
  12  *
  13  * This program is free software; you can redistribute it and/or
  14  * modify it under the terms of the GNU General Public License version 2
  15  * as published by the Free Software Foundation; or, when distributed
  16  * separately from the Linux kernel or incorporated into other
  17  * software packages, subject to the following license:
  18  *
  19  * Permission is hereby granted, free of charge, to any person obtaining a copy
  20  * of this source file (the "Software"), to deal in the Software without
  21  * restriction, including without limitation the rights to use, copy, modify,
  22  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  23  * and to permit persons to whom the Software is furnished to do so, subject to
  24  * the following conditions:
  25  *
  26  * The above copyright notice and this permission notice shall be included in
  27  * all copies or substantial portions of the Software.
  28  *
  29  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  30  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  31  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  32  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  33  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  34  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  35  * IN THE SOFTWARE.
  36  */
  37
  38 #include <linux/interrupt.h>
  39 #include <linux/blkdev.h>
  40 #include <linux/blk-mq.h>
  41 #include <linux/hdreg.h>
  42 #include <linux/cdrom.h>
  43 #include <linux/module.h>
  44 #include <linux/slab.h>
  45 #include <linux/mutex.h>
  46 #include <linux/scatterlist.h>
  47 #include <linux/bitmap.h>
  48 #include <linux/list.h>
  49
  50 #include <xen/xen.h>
  51 #include <xen/xenbus.h>
  52 #include <xen/grant_table.h>
  53 #include <xen/events.h>
  54 #include <xen/page.h>
  55 #include <xen/platform_pci.h>
  56
  57 #include <xen/interface/grant_table.h>
  58 #include <xen/interface/io/blkif.h>
  59 #include <xen/interface/io/protocols.h>
  60
  61 #include <asm/xen/hypervisor.h>
  62
  63 /*
  64  * The minimal size of segment supported by the block framework is PAGE_SIZE.
  65  * When Linux is using a different page size than Xen, it may not be possible
  66  * to put all the data in a single segment.
  67  * This can happen when the backend doesn't support indirect descriptor and
  68  * therefore the maximum amount of data that a request can carry is
  69  * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
  70  *
  71  * Note that we only support one extra request. So the Linux page size
  72  * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
  73  * 88KB.
  74  */
  75 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
  76
  77 enum blkif_state {
  78         BLKIF_STATE_DISCONNECTED,
  79         BLKIF_STATE_CONNECTED,
  80         BLKIF_STATE_SUSPENDED,
  81 };
  82
  83 struct grant {
  84         grant_ref_t gref;
  85         struct page *page;
  86         struct list_head node;
  87 };
  88
  89 enum blk_req_status {
  90         REQ_WAITING,
  91         REQ_DONE,
  92         REQ_ERROR,
  93         REQ_EOPNOTSUPP,
  94 };
  95
  96 struct blk_shadow {
  97         struct blkif_request req;
  98         struct request *request;
  99         struct grant **grants_used;
 100         struct grant **indirect_grants;
 101         struct scatterlist *sg;
 102         unsigned int num_sg;
 103         enum blk_req_status status;
 104
 105         #define NO_ASSOCIATED_ID ~0UL
 106         /*
 107          * Id of the sibling if we ever need 2 requests when handling a
 108          * block I/O request
 109          */
 110         unsigned long associated_id;
 111 };
 112
 113 struct blkif_req {
 114         blk_status_t    error;
 115 };
 116
 117 static inline struct blkif_req *blkif_req(struct request *rq)
 118 {
 119         return blk_mq_rq_to_pdu(rq);
 120 }
 121
 122 static DEFINE_MUTEX(blkfront_mutex);
 123 static const struct block_device_operations xlvbd_block_fops;
 124
 125 /*
 126  * Maximum number of segments in indirect requests, the actual value used by
 127  * the frontend driver is the minimum of this value and the value provided
 128  * by the backend driver.
 129  */
 130
 131 static unsigned int xen_blkif_max_segments = 32;
 132 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
 133 MODULE_PARM_DESC(max_indirect_segments,
 134                  "Maximum amount of segments in indirect requests (default is 32)");
 135
 136 static unsigned int xen_blkif_max_queues = 4;
 137 module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
 138 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
 139
 140 /*
 141  * Maximum order of pages to be used for the shared ring between front and
 142  * backend, 4KB page granularity is used.
 143  */
 144 static unsigned int xen_blkif_max_ring_order;
 145 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
 146 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
 147
 148 #define BLK_RING_SIZE(info)     \
 149         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
 150
 151 #define BLK_MAX_RING_SIZE       \
 152         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS)
 153
 154 /*
 155  * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
 156  * characters are enough. Define to 20 to keep consistent with backend.
 157  */
 158 #define RINGREF_NAME_LEN (20)
 159 /*
 160  * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
 161  */
 162 #define QUEUE_NAME_LEN (17)
 163
 164 /*
 165  *  Per-ring info.
 166  *  Every blkfront device can associate with one or more blkfront_ring_info,
 167  *  depending on how many hardware queues/rings to be used.
 168  */
 169 struct blkfront_ring_info {
 170         /* Lock to protect data in every ring buffer. */
 171         spinlock_t ring_lock;
 172         struct blkif_front_ring ring;
 173         unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
 174         unsigned int evtchn, irq;
 175         struct work_struct work;
 176         struct gnttab_free_callback callback;
 177         struct blk_shadow shadow[BLK_MAX_RING_SIZE];
 178         struct list_head indirect_pages;
 179         struct list_head grants;
 180         unsigned int persistent_gnts_c;
 181         unsigned long shadow_free;
 182         struct blkfront_info *dev_info;
 183 };
 184
 185 /*
 186  * We have one of these per vbd, whether ide, scsi or 'other'.  They
 187  * hang in private_data off the gendisk structure. We may end up
 188  * putting all kinds of interesting stuff here :-)
 189  */
 190 struct blkfront_info
 191 {
 192         struct mutex mutex;
 193         struct xenbus_device *xbdev;
 194         struct gendisk *gd;
 195         u16 sector_size;
 196         unsigned int physical_sector_size;
 197         int vdevice;
 198         blkif_vdev_t handle;
 199         enum blkif_state connected;
 200         /* Number of pages per ring buffer. */
 201         unsigned int nr_ring_pages;
 202         struct request_queue *rq;
 203         unsigned int feature_flush:1;
 204         unsigned int feature_fua:1;
 205         unsigned int feature_discard:1;
 206         unsigned int feature_secdiscard:1;
 207         unsigned int feature_persistent:1;
 208         unsigned int discard_granularity;
 209         unsigned int discard_alignment;
 210         /* Number of 4KB segments handled */
 211         unsigned int max_indirect_segments;
 212         int is_ready;
 213         struct blk_mq_tag_set tag_set;
 214         struct blkfront_ring_info *rinfo;
 215         unsigned int nr_rings;
 216         /* Save uncomplete reqs and bios for migration. */
 217         struct list_head requests;
 218         struct bio_list bio_list;
 219 };
 220
 221 static unsigned int nr_minors;
 222 static unsigned long *minors;
 223 static DEFINE_SPINLOCK(minor_lock);
 224
 225 #define GRANT_INVALID_REF       0
 226
 227 #define PARTS_PER_DISK          16
 228 #define PARTS_PER_EXT_DISK      256
 229
 230 #define BLKIF_MAJOR(dev) ((dev)>>8)
 231 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 232
 233 #define EXT_SHIFT 28
 234 #define EXTENDED (1<<EXT_SHIFT)
 235 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 236 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 237 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 238 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 239 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 240 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 241
 242 #define DEV_NAME        "xvd"   /* name in /dev */
 243
 244 /*
 245  * Grants are always the same size as a Xen page (i.e 4KB).
 246  * A physical segment is always the same size as a Linux page.
 247  * Number of grants per physical segment
 248  */
 249 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
 250
 251 #define GRANTS_PER_INDIRECT_FRAME \
 252         (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
 253
 254 #define INDIRECT_GREFS(_grants)         \
 255         DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
 256
 257 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 258 static void blkfront_gather_backend_features(struct blkfront_info *info);
 259 static int negotiate_mq(struct blkfront_info *info);
 260
 261 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 262 {
 263         unsigned long free = rinfo->shadow_free;
 264
 265         BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
 266         rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
 267         rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 268         return free;
 269 }
 270
 271 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
 272                               unsigned long id)
 273 {
 274         if (rinfo->shadow[id].req.u.rw.id != id)
 275                 return -EINVAL;
 276         if (rinfo->shadow[id].request == NULL)
 277                 return -EINVAL;
 278         rinfo->shadow[id].req.u.rw.id  = rinfo->shadow_free;
 279         rinfo->shadow[id].request = NULL;
 280         rinfo->shadow_free = id;
 281         return 0;
 282 }
 283
 284 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 285 {
 286         struct blkfront_info *info = rinfo->dev_info;
 287         struct page *granted_page;
 288         struct grant *gnt_list_entry, *n;
 289         int i = 0;
 290
 291         while (i < num) {
 292                 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
 293                 if (!gnt_list_entry)
 294                         goto out_of_memory;
 295
 296                 if (info->feature_persistent) {
 297                         granted_page = alloc_page(GFP_NOIO);
 298                         if (!granted_page) {
 299                                 kfree(gnt_list_entry);
 300                                 goto out_of_memory;
 301                         }
 302                         gnt_list_entry->page = granted_page;
 303                 }
 304
 305                 gnt_list_entry->gref = GRANT_INVALID_REF;
 306                 list_add(&gnt_list_entry->node, &rinfo->grants);
 307                 i++;
 308         }
 309
 310         return 0;
 311
 312 out_of_memory:
 313         list_for_each_entry_safe(gnt_list_entry, n,
 314                                  &rinfo->grants, node) {
 315                 list_del(&gnt_list_entry->node);
 316                 if (info->feature_persistent)
 317                         __free_page(gnt_list_entry->page);
 318                 kfree(gnt_list_entry);
 319                 i--;
 320         }
 321         BUG_ON(i != 0);
 322         return -ENOMEM;
 323 }
 324
 325 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
 326 {
 327         struct grant *gnt_list_entry;
 328
 329         BUG_ON(list_empty(&rinfo->grants));
 330         gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
 331                                           node);
 332         list_del(&gnt_list_entry->node);
 333
 334         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 335                 rinfo->persistent_gnts_c--;
 336
 337         return gnt_list_entry;
 338 }
 339
 340 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
 341                                         const struct blkfront_info *info)
 342 {
 343         gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
 344                                                  info->xbdev->otherend_id,
 345                                                  gnt_list_entry->page,
 346                                                  0);
 347 }
 348
 349 static struct grant *get_grant(grant_ref_t *gref_head,
 350                                unsigned long gfn,
 351                                struct blkfront_ring_info *rinfo)
 352 {
 353         struct grant *gnt_list_entry = get_free_grant(rinfo);
 354         struct blkfront_info *info = rinfo->dev_info;
 355
 356         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 357                 return gnt_list_entry;
 358
 359         /* Assign a gref to this page */
 360         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 361         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 362         if (info->feature_persistent)
 363                 grant_foreign_access(gnt_list_entry, info);
 364         else {
 365                 /* Grant access to the GFN passed by the caller */
 366                 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
 367                                                 info->xbdev->otherend_id,
 368                                                 gfn, 0);
 369         }
 370
 371         return gnt_list_entry;
 372 }
 373
 374 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
 375                                         struct blkfront_ring_info *rinfo)
 376 {
 377         struct grant *gnt_list_entry = get_free_grant(rinfo);
 378         struct blkfront_info *info = rinfo->dev_info;
 379
 380         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 381                 return gnt_list_entry;
 382
 383         /* Assign a gref to this page */
 384         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 385         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 386         if (!info->feature_persistent) {
 387                 struct page *indirect_page;
 388
 389                 /* Fetch a pre-allocated page to use for indirect grefs */
 390                 BUG_ON(list_empty(&rinfo->indirect_pages));
 391                 indirect_page = list_first_entry(&rinfo->indirect_pages,
 392                                                  struct page, lru);
 393                 list_del(&indirect_page->lru);
 394                 gnt_list_entry->page = indirect_page;
 395         }
 396         grant_foreign_access(gnt_list_entry, info);
 397
 398         return gnt_list_entry;
 399 }
 400
 401 static const char *op_name(int op)
 402 {
 403         static const char *const names[] = {
 404                 [BLKIF_OP_READ] = "read",
 405                 [BLKIF_OP_WRITE] = "write",
 406                 [BLKIF_OP_WRITE_BARRIER] = "barrier",
 407                 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
 408                 [BLKIF_OP_DISCARD] = "discard" };
 409
 410         if (op < 0 || op >= ARRAY_SIZE(names))
 411                 return "unknown";
 412
 413         if (!names[op])
 414                 return "reserved";
 415
 416         return names[op];
 417 }
 418 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 419 {
 420         unsigned int end = minor + nr;
 421         int rc;
 422
 423         if (end > nr_minors) {
 424                 unsigned long *bitmap, *old;
 425
 426                 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 427                                  GFP_KERNEL);
 428                 if (bitmap == NULL)
 429                         return -ENOMEM;
 430
 431                 spin_lock(&minor_lock);
 432                 if (end > nr_minors) {
 433                         old = minors;
 434                         memcpy(bitmap, minors,
 435                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 436                         minors = bitmap;
 437                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 438                 } else
 439                         old = bitmap;
 440                 spin_unlock(&minor_lock);
 441                 kfree(old);
 442         }
 443
 444         spin_lock(&minor_lock);
 445         if (find_next_bit(minors, end, minor) >= end) {
 446                 bitmap_set(minors, minor, nr);
 447                 rc = 0;
 448         } else
 449                 rc = -EBUSY;
 450         spin_unlock(&minor_lock);
 451
 452         return rc;
 453 }
 454
 455 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 456 {
 457         unsigned int end = minor + nr;
 458
 459         BUG_ON(end > nr_minors);
 460         spin_lock(&minor_lock);
 461         bitmap_clear(minors,  minor, nr);
 462         spin_unlock(&minor_lock);
 463 }
 464
 465 static void blkif_restart_queue_callback(void *arg)
 466 {
 467         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
 468         schedule_work(&rinfo->work);
 469 }
 470
 471 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 472 {
 473         /* We don't have real geometry info, but let's at least return
 474            values consistent with the size of the device */
 475         sector_t nsect = get_capacity(bd->bd_disk);
 476         sector_t cylinders = nsect;
 477
 478         hg->heads = 0xff;
 479         hg->sectors = 0x3f;
 480         sector_div(cylinders, hg->heads * hg->sectors);
 481         hg->cylinders = cylinders;
 482         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 483                 hg->cylinders = 0xffff;
 484         return 0;
 485 }
 486
 487 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 488                        unsigned command, unsigned long argument)
 489 {
 490         struct blkfront_info *info = bdev->bd_disk->private_data;
 491         int i;
 492
 493         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 494                 command, (long)argument);
 495
 496         switch (command) {
 497         case CDROMMULTISESSION:
 498                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 499                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 500                         if (put_user(0, (char __user *)(argument + i)))
 501                                 return -EFAULT;
 502                 return 0;
 503
 504         case CDROM_GET_CAPABILITY: {
 505                 struct gendisk *gd = info->gd;
 506                 if (gd->flags & GENHD_FL_CD)
 507                         return 0;
 508                 return -EINVAL;
 509         }
 510
 511         default:
 512                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 513                   command);*/
 514                 return -EINVAL; /* same return as native Linux */
 515         }
 516
 517         return 0;
 518 }
 519
 520 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 521                                             struct request *req,
 522                                             struct blkif_request **ring_req)
 523 {
 524         unsigned long id;
 525
 526         *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
 527         rinfo->ring.req_prod_pvt++;
 528
 529         id = get_id_from_freelist(rinfo);
 530         rinfo->shadow[id].request = req;
 531         rinfo->shadow[id].status = REQ_WAITING;
 532         rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
 533
 534         (*ring_req)->u.rw.id = id;
 535
 536         return id;
 537 }
 538
 539 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
 540 {
 541         struct blkfront_info *info = rinfo->dev_info;
 542         struct blkif_request *ring_req;
 543         unsigned long id;
 544
 545         /* Fill out a communications ring structure. */
 546         id = blkif_ring_get_request(rinfo, req, &ring_req);
 547
 548         ring_req->operation = BLKIF_OP_DISCARD;
 549         ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
 550         ring_req->u.discard.id = id;
 551         ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
 552         if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
 553                 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
 554         else
 555                 ring_req->u.discard.flag = 0;
 556
 557         /* Keep a private copy so we can reissue requests when recovering. */
 558         rinfo->shadow[id].req = *ring_req;
 559
 560         return 0;
 561 }
 562
 563 struct setup_rw_req {
 564         unsigned int grant_idx;
 565         struct blkif_request_segment *segments;
 566         struct blkfront_ring_info *rinfo;
 567         struct blkif_request *ring_req;
 568         grant_ref_t gref_head;
 569         unsigned int id;
 570         /* Only used when persistent grant is used and it's a read request */
 571         bool need_copy;
 572         unsigned int bvec_off;
 573         char *bvec_data;
 574
 575         bool require_extra_req;
 576         struct blkif_request *extra_ring_req;
 577 };
 578
 579 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
 580                                      unsigned int len, void *data)
 581 {
 582         struct setup_rw_req *setup = data;
 583         int n, ref;
 584         struct grant *gnt_list_entry;
 585         unsigned int fsect, lsect;
 586         /* Convenient aliases */
 587         unsigned int grant_idx = setup->grant_idx;
 588         struct blkif_request *ring_req = setup->ring_req;
 589         struct blkfront_ring_info *rinfo = setup->rinfo;
 590         /*
 591          * We always use the shadow of the first request to store the list
 592          * of grant associated to the block I/O request. This made the
 593          * completion more easy to handle even if the block I/O request is
 594          * split.
 595          */
 596         struct blk_shadow *shadow = &rinfo->shadow[setup->id];
 597
 598         if (unlikely(setup->require_extra_req &&
 599                      grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
 600                 /*
 601                  * We are using the second request, setup grant_idx
 602                  * to be the index of the segment array.
 603                  */
 604                 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
 605                 ring_req = setup->extra_ring_req;
 606         }
 607
 608         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 609             (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
 610                 if (setup->segments)
 611                         kunmap_atomic(setup->segments);
 612
 613                 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
 614                 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
 615                 shadow->indirect_grants[n] = gnt_list_entry;
 616                 setup->segments = kmap_atomic(gnt_list_entry->page);
 617                 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 618         }
 619
 620         gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
 621         ref = gnt_list_entry->gref;
 622         /*
 623          * All the grants are stored in the shadow of the first
 624          * request. Therefore we have to use the global index.
 625          */
 626         shadow->grants_used[setup->grant_idx] = gnt_list_entry;
 627
 628         if (setup->need_copy) {
 629                 void *shared_data;
 630
 631                 shared_data = kmap_atomic(gnt_list_entry->page);
 632                 /*
 633                  * this does not wipe data stored outside the
 634                  * range sg->offset..sg->offset+sg->length.
 635                  * Therefore, blkback *could* see data from
 636                  * previous requests. This is OK as long as
 637                  * persistent grants are shared with just one
 638                  * domain. It may need refactoring if this
 639                  * changes
 640                  */
 641                 memcpy(shared_data + offset,
 642                        setup->bvec_data + setup->bvec_off,
 643                        len);
 644
 645                 kunmap_atomic(shared_data);
 646                 setup->bvec_off += len;
 647         }
 648
 649         fsect = offset >> 9;
 650         lsect = fsect + (len >> 9) - 1;
 651         if (ring_req->operation != BLKIF_OP_INDIRECT) {
 652                 ring_req->u.rw.seg[grant_idx] =
 653                         (struct blkif_request_segment) {
 654                                 .gref       = ref,
 655                                 .first_sect = fsect,
 656                                 .last_sect  = lsect };
 657         } else {
 658                 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
 659                         (struct blkif_request_segment) {
 660                                 .gref       = ref,
 661                                 .first_sect = fsect,
 662                                 .last_sect  = lsect };
 663         }
 664
 665         (setup->grant_idx)++;
 666 }
 667
 668 static void blkif_setup_extra_req(struct blkif_request *first,
 669                                   struct blkif_request *second)
 670 {
 671         uint16_t nr_segments = first->u.rw.nr_segments;
 672
 673         /*
 674          * The second request is only present when the first request uses
 675          * all its segments. It's always the continuity of the first one.
 676          */
 677         first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 678
 679         second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
 680         second->u.rw.sector_number = first->u.rw.sector_number +
 681                 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
 682
 683         second->u.rw.handle = first->u.rw.handle;
 684         second->operation = first->operation;
 685 }
 686
 687 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
 688 {
 689         struct blkfront_info *info = rinfo->dev_info;
 690         struct blkif_request *ring_req, *extra_ring_req = NULL;
 691         unsigned long id, extra_id = NO_ASSOCIATED_ID;
 692         bool require_extra_req = false;
 693         int i;
 694         struct setup_rw_req setup = {
 695                 .grant_idx = 0,
 696                 .segments = NULL,
 697                 .rinfo = rinfo,
 698                 .need_copy = rq_data_dir(req) && info->feature_persistent,
 699         };
 700
 701         /*
 702          * Used to store if we are able to queue the request by just using
 703          * existing persistent grants, or if we have to get new grants,
 704          * as there are not sufficiently many free.
 705          */
 706         bool new_persistent_gnts = false;
 707         struct scatterlist *sg;
 708         int num_sg, max_grefs, num_grant;
 709
 710         max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
 711         if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
 712                 /*
 713                  * If we are using indirect segments we need to account
 714                  * for the indirect grefs used in the request.
 715                  */
 716                 max_grefs += INDIRECT_GREFS(max_grefs);
 717
 718         /* Check if we have enough persistent grants to allocate a requests */
 719         if (rinfo->persistent_gnts_c < max_grefs) {
 720                 new_persistent_gnts = true;
 721
 722                 if (gnttab_alloc_grant_references(
 723                     max_grefs - rinfo->persistent_gnts_c,
 724                     &setup.gref_head) < 0) {
 725                         gnttab_request_free_callback(
 726                                 &rinfo->callback,
 727                                 blkif_restart_queue_callback,
 728                                 rinfo,
 729                                 max_grefs - rinfo->persistent_gnts_c);
 730                         return 1;
 731                 }
 732         }
 733
 734         /* Fill out a communications ring structure. */
 735         id = blkif_ring_get_request(rinfo, req, &ring_req);
 736
 737         num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 738         num_grant = 0;
 739         /* Calculate the number of grant used */
 740         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
 741                num_grant += gnttab_count_grant(sg->offset, sg->length);
 742
 743         require_extra_req = info->max_indirect_segments == 0 &&
 744                 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
 745         BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
 746
 747         rinfo->shadow[id].num_sg = num_sg;
 748         if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
 749             likely(!require_extra_req)) {
 750                 /*
 751                  * The indirect operation can only be a BLKIF_OP_READ or
 752                  * BLKIF_OP_WRITE
 753                  */
 754                 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
 755                 ring_req->operation = BLKIF_OP_INDIRECT;
 756                 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
 757                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 758                 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
 759                 ring_req->u.indirect.handle = info->handle;
 760                 ring_req->u.indirect.nr_segments = num_grant;
 761         } else {
 762                 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 763                 ring_req->u.rw.handle = info->handle;
 764                 ring_req->operation = rq_data_dir(req) ?
 765                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 766                 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
 767                         /*
 768                          * Ideally we can do an unordered flush-to-disk.
 769                          * In case the backend onlysupports barriers, use that.
 770                          * A barrier request a superset of FUA, so we can
 771                          * implement it the same way.  (It's also a FLUSH+FUA,
 772                          * since it is guaranteed ordered WRT previous writes.)
 773                          */
 774                         if (info->feature_flush && info->feature_fua)
 775                                 ring_req->operation =
 776                                         BLKIF_OP_WRITE_BARRIER;
 777                         else if (info->feature_flush)
 778                                 ring_req->operation =
 779                                         BLKIF_OP_FLUSH_DISKCACHE;
 780                         else
 781                                 ring_req->operation = 0;
 782                 }
 783                 ring_req->u.rw.nr_segments = num_grant;
 784                 if (unlikely(require_extra_req)) {
 785                         extra_id = blkif_ring_get_request(rinfo, req,
 786                                                           &extra_ring_req);
 787                         /*
 788                          * Only the first request contains the scatter-gather
 789                          * list.
 790                          */
 791                         rinfo->shadow[extra_id].num_sg = 0;
 792
 793                         blkif_setup_extra_req(ring_req, extra_ring_req);
 794
 795                         /* Link the 2 requests together */
 796                         rinfo->shadow[extra_id].associated_id = id;
 797                         rinfo->shadow[id].associated_id = extra_id;
 798                 }
 799         }
 800
 801         setup.ring_req = ring_req;
 802         setup.id = id;
 803
 804         setup.require_extra_req = require_extra_req;
 805         if (unlikely(require_extra_req))
 806                 setup.extra_ring_req = extra_ring_req;
 807
 808         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
 809                 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
 810
 811                 if (setup.need_copy) {
 812                         setup.bvec_off = sg->offset;
 813                         setup.bvec_data = kmap_atomic(sg_page(sg));
 814                 }
 815
 816                 gnttab_foreach_grant_in_range(sg_page(sg),
 817                                               sg->offset,
 818                                               sg->length,
 819                                               blkif_setup_rw_req_grant,
 820                                               &setup);
 821
 822                 if (setup.need_copy)
 823                         kunmap_atomic(setup.bvec_data);
 824         }
 825         if (setup.segments)
 826                 kunmap_atomic(setup.segments);
 827
 828         /* Keep a private copy so we can reissue requests when recovering. */
 829         rinfo->shadow[id].req = *ring_req;
 830         if (unlikely(require_extra_req))
 831                 rinfo->shadow[extra_id].req = *extra_ring_req;
 832
 833         if (new_persistent_gnts)
 834                 gnttab_free_grant_references(setup.gref_head);
 835
 836         return 0;
 837 }
 838
 839 /*
 840  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 841  * and writes are handled as expected.
 842  *
 843  * @req: a request struct
 844  */
 845 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
 846 {
 847         if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
 848                 return 1;
 849
 850         if (unlikely(req_op(req) == REQ_OP_DISCARD ||
 851                      req_op(req) == REQ_OP_SECURE_ERASE))
 852                 return blkif_queue_discard_req(req, rinfo);
 853         else
 854                 return blkif_queue_rw_req(req, rinfo);
 855 }
 856
 857 static inline void flush_requests(struct blkfront_ring_info *rinfo)
 858 {
 859         int notify;
 860
 861         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
 862
 863         if (notify)
 864                 notify_remote_via_irq(rinfo->irq);
 865 }
 866
 867 static inline bool blkif_request_flush_invalid(struct request *req,
 868                                                struct blkfront_info *info)
 869 {
 870         return (blk_rq_is_passthrough(req) ||
 871                 ((req_op(req) == REQ_OP_FLUSH) &&
 872                  !info->feature_flush) ||
 873                 ((req->cmd_flags & REQ_FUA) &&
 874                  !info->feature_fua));
 875 }
 876
 877 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
 878                           const struct blk_mq_queue_data *qd)
 879 {
 880         unsigned long flags;
 881         int qid = hctx->queue_num;
 882         struct blkfront_info *info = hctx->queue->queuedata;
 883         struct blkfront_ring_info *rinfo = NULL;
 884
 885         BUG_ON(info->nr_rings <= qid);
 886         rinfo = &info->rinfo[qid];
 887         blk_mq_start_request(qd->rq);
 888         spin_lock_irqsave(&rinfo->ring_lock, flags);
 889         if (RING_FULL(&rinfo->ring))
 890                 goto out_busy;
 891
 892         if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
 893                 goto out_err;
 894
 895         if (blkif_queue_request(qd->rq, rinfo))
 896                 goto out_busy;
 897
 898         flush_requests(rinfo);
 899         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 900         return BLK_STS_OK;
 901
 902 out_err:
 903         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 904         return BLK_STS_IOERR;
 905
 906 out_busy:
 907         blk_mq_stop_hw_queue(hctx);
 908         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 909         return BLK_STS_DEV_RESOURCE;
 910 }
 911
 912 static void blkif_complete_rq(struct request *rq)
 913 {
 914         blk_mq_end_request(rq, blkif_req(rq)->error);
 915 }
 916
 917 static const struct blk_mq_ops blkfront_mq_ops = {
 918         .queue_rq = blkif_queue_rq,
 919         .complete = blkif_complete_rq,
 920 };
 921
 922 static void blkif_set_queue_limits(struct blkfront_info *info)
 923 {
 924         struct request_queue *rq = info->rq;
 925         struct gendisk *gd = info->gd;
 926         unsigned int segments = info->max_indirect_segments ? :
 927                                 BLKIF_MAX_SEGMENTS_PER_REQUEST;
 928
 929         blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
 930
 931         if (info->feature_discard) {
 932                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
 933                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
 934                 rq->limits.discard_granularity = info->discard_granularity;
 935                 rq->limits.discard_alignment = info->discard_alignment;
 936                 if (info->feature_secdiscard)
 937                         blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
 938         }
 939
 940         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 941         blk_queue_logical_block_size(rq, info->sector_size);
 942         blk_queue_physical_block_size(rq, info->physical_sector_size);
 943         blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
 944
 945         /* Each segment in a request is up to an aligned page in size. */
 946         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 947         blk_queue_max_segment_size(rq, PAGE_SIZE);
 948
 949         /* Ensure a merged request will fit in a single I/O ring slot. */
 950         blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
 951
 952         /* Make sure buffer addresses are sector-aligned. */
 953         blk_queue_dma_alignment(rq, 511);
 954 }
 955
 956 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 957                                 unsigned int physical_sector_size)
 958 {
 959         struct request_queue *rq;
 960         struct blkfront_info *info = gd->private_data;
 961
 962         memset(&info->tag_set, 0, sizeof(info->tag_set));
 963         info->tag_set.ops = &blkfront_mq_ops;
 964         info->tag_set.nr_hw_queues = info->nr_rings;
 965         if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
 966                 /*
 967                  * When indirect descriptior is not supported, the I/O request
 968                  * will be split between multiple request in the ring.
 969                  * To avoid problems when sending the request, divide by
 970                  * 2 the depth of the queue.
 971                  */
 972                 info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
 973         } else
 974                 info->tag_set.queue_depth = BLK_RING_SIZE(info);
 975         info->tag_set.numa_node = NUMA_NO_NODE;
 976         info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_SG_MERGE;
 977         info->tag_set.cmd_size = sizeof(struct blkif_req);
 978         info->tag_set.driver_data = info;
 979
 980         if (blk_mq_alloc_tag_set(&info->tag_set))
 981                 return -EINVAL;
 982         rq = blk_mq_init_queue(&info->tag_set);
 983         if (IS_ERR(rq)) {
 984                 blk_mq_free_tag_set(&info->tag_set);
 985                 return PTR_ERR(rq);
 986         }
 987
 988         rq->queuedata = info;
 989         info->rq = gd->queue = rq;
 990         info->gd = gd;
 991         info->sector_size = sector_size;
 992         info->physical_sector_size = physical_sector_size;
 993         blkif_set_queue_limits(info);
 994
 995         return 0;
 996 }
 997
 998 static const char *flush_info(struct blkfront_info *info)
 999 {
1000         if (info->feature_flush && info->feature_fua)
1001                 return "barrier: enabled;";
1002         else if (info->feature_flush)
1003                 return "flush diskcache: enabled;";
1004         else
1005                 return "barrier or flush: disabled;";
1006 }
1007
1008 static void xlvbd_flush(struct blkfront_info *info)
1009 {
1010         blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
1011                               info->feature_fua ? true : false);
1012         pr_info("blkfront: %s: %s %s %s %s %s\n",
1013                 info->gd->disk_name, flush_info(info),
1014                 "persistent grants:", info->feature_persistent ?
1015                 "enabled;" : "disabled;", "indirect descriptors:",
1016                 info->max_indirect_segments ? "enabled;" : "disabled;");
1017 }
1018
1019 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1020 {
1021         int major;
1022         major = BLKIF_MAJOR(vdevice);
1023         *minor = BLKIF_MINOR(vdevice);
1024         switch (major) {
1025                 case XEN_IDE0_MAJOR:
1026                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1027                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
1028                                 EMULATED_HD_DISK_MINOR_OFFSET;
1029                         break;
1030                 case XEN_IDE1_MAJOR:
1031                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1032                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1033                                 EMULATED_HD_DISK_MINOR_OFFSET;
1034                         break;
1035                 case XEN_SCSI_DISK0_MAJOR:
1036                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1037                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1038                         break;
1039                 case XEN_SCSI_DISK1_MAJOR:
1040                 case XEN_SCSI_DISK2_MAJOR:
1041                 case XEN_SCSI_DISK3_MAJOR:
1042                 case XEN_SCSI_DISK4_MAJOR:
1043                 case XEN_SCSI_DISK5_MAJOR:
1044                 case XEN_SCSI_DISK6_MAJOR:
1045                 case XEN_SCSI_DISK7_MAJOR:
1046                         *offset = (*minor / PARTS_PER_DISK) +
1047                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1048                                 EMULATED_SD_DISK_NAME_OFFSET;
1049                         *minor = *minor +
1050                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1051                                 EMULATED_SD_DISK_MINOR_OFFSET;
1052                         break;
1053                 case XEN_SCSI_DISK8_MAJOR:
1054                 case XEN_SCSI_DISK9_MAJOR:
1055                 case XEN_SCSI_DISK10_MAJOR:
1056                 case XEN_SCSI_DISK11_MAJOR:
1057                 case XEN_SCSI_DISK12_MAJOR:
1058                 case XEN_SCSI_DISK13_MAJOR:
1059                 case XEN_SCSI_DISK14_MAJOR:
1060                 case XEN_SCSI_DISK15_MAJOR:
1061                         *offset = (*minor / PARTS_PER_DISK) +
1062                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1063                                 EMULATED_SD_DISK_NAME_OFFSET;
1064                         *minor = *minor +
1065                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1066                                 EMULATED_SD_DISK_MINOR_OFFSET;
1067                         break;
1068                 case XENVBD_MAJOR:
1069                         *offset = *minor / PARTS_PER_DISK;
1070                         break;
1071                 default:
1072                         printk(KERN_WARNING "blkfront: your disk configuration is "
1073                                         "incorrect, please use an xvd device instead\n");
1074                         return -ENODEV;
1075         }
1076         return 0;
1077 }
1078
1079 static char *encode_disk_name(char *ptr, unsigned int n)
1080 {
1081         if (n >= 26)
1082                 ptr = encode_disk_name(ptr, n / 26 - 1);
1083         *ptr = 'a' + n % 26;
1084         return ptr + 1;
1085 }
1086
1087 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1088                                struct blkfront_info *info,
1089                                u16 vdisk_info, u16 sector_size,
1090                                unsigned int physical_sector_size)
1091 {
1092         struct gendisk *gd;
1093         int nr_minors = 1;
1094         int err;
1095         unsigned int offset;
1096         int minor;
1097         int nr_parts;
1098         char *ptr;
1099
1100         BUG_ON(info->gd != NULL);
1101         BUG_ON(info->rq != NULL);
1102
1103         if ((info->vdevice>>EXT_SHIFT) > 1) {
1104                 /* this is above the extended range; something is wrong */
1105                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1106                 return -ENODEV;
1107         }
1108
1109         if (!VDEV_IS_EXTENDED(info->vdevice)) {
1110                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1111                 if (err)
1112                         return err;
1113                 nr_parts = PARTS_PER_DISK;
1114         } else {
1115                 minor = BLKIF_MINOR_EXT(info->vdevice);
1116                 nr_parts = PARTS_PER_EXT_DISK;
1117                 offset = minor / nr_parts;
1118                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1119                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1120                                         "emulated IDE disks,\n\t choose an xvd device name"
1121                                         "from xvde on\n", info->vdevice);
1122         }
1123         if (minor >> MINORBITS) {
1124                 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1125                         info->vdevice, minor);
1126                 return -ENODEV;
1127         }
1128
1129         if ((minor % nr_parts) == 0)
1130                 nr_minors = nr_parts;
1131
1132         err = xlbd_reserve_minors(minor, nr_minors);
1133         if (err)
1134                 goto out;
1135         err = -ENODEV;
1136
1137         gd = alloc_disk(nr_minors);
1138         if (gd == NULL)
1139                 goto release;
1140
1141         strcpy(gd->disk_name, DEV_NAME);
1142         ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1143         BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1144         if (nr_minors > 1)
1145                 *ptr = 0;
1146         else
1147                 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1148                          "%d", minor & (nr_parts - 1));
1149
1150         gd->major = XENVBD_MAJOR;
1151         gd->first_minor = minor;
1152         gd->fops = &xlvbd_block_fops;
1153         gd->private_data = info;
1154         set_capacity(gd, capacity);
1155
1156         if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
1157                 del_gendisk(gd);
1158                 goto release;
1159         }
1160
1161         xlvbd_flush(info);
1162
1163         if (vdisk_info & VDISK_READONLY)
1164                 set_disk_ro(gd, 1);
1165
1166         if (vdisk_info & VDISK_REMOVABLE)
1167                 gd->flags |= GENHD_FL_REMOVABLE;
1168
1169         if (vdisk_info & VDISK_CDROM)
1170                 gd->flags |= GENHD_FL_CD;
1171
1172         return 0;
1173
1174  release:
1175         xlbd_release_minors(minor, nr_minors);
1176  out:
1177         return err;
1178 }
1179
1180 static void xlvbd_release_gendisk(struct blkfront_info *info)
1181 {
1182         unsigned int minor, nr_minors, i;
1183
1184         if (info->rq == NULL)
1185                 return;
1186
1187         /* No more blkif_request(). */
1188         blk_mq_stop_hw_queues(info->rq);
1189
1190         for (i = 0; i < info->nr_rings; i++) {
1191                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1192
1193                 /* No more gnttab callback work. */
1194                 gnttab_cancel_free_callback(&rinfo->callback);
1195
1196                 /* Flush gnttab callback work. Must be done with no locks held. */
1197                 flush_work(&rinfo->work);
1198         }
1199
1200         del_gendisk(info->gd);
1201
1202         minor = info->gd->first_minor;
1203         nr_minors = info->gd->minors;
1204         xlbd_release_minors(minor, nr_minors);
1205
1206         blk_cleanup_queue(info->rq);
1207         blk_mq_free_tag_set(&info->tag_set);
1208         info->rq = NULL;
1209
1210         put_disk(info->gd);
1211         info->gd = NULL;
1212 }
1213
1214 /* Already hold rinfo->ring_lock. */
1215 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1216 {
1217         if (!RING_FULL(&rinfo->ring))
1218                 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1219 }
1220
1221 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1222 {
1223         unsigned long flags;
1224
1225         spin_lock_irqsave(&rinfo->ring_lock, flags);
1226         kick_pending_request_queues_locked(rinfo);
1227         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1228 }
1229
1230 static void blkif_restart_queue(struct work_struct *work)
1231 {
1232         struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1233
1234         if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1235                 kick_pending_request_queues(rinfo);
1236 }
1237
1238 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1239 {
1240         struct grant *persistent_gnt, *n;
1241         struct blkfront_info *info = rinfo->dev_info;
1242         int i, j, segs;
1243
1244         /*
1245          * Remove indirect pages, this only happens when using indirect
1246          * descriptors but not persistent grants
1247          */
1248         if (!list_empty(&rinfo->indirect_pages)) {
1249                 struct page *indirect_page, *n;
1250
1251                 BUG_ON(info->feature_persistent);
1252                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1253                         list_del(&indirect_page->lru);
1254                         __free_page(indirect_page);
1255                 }
1256         }
1257
1258         /* Remove all persistent grants. */
1259         if (!list_empty(&rinfo->grants)) {
1260                 list_for_each_entry_safe(persistent_gnt, n,
1261                                          &rinfo->grants, node) {
1262                         list_del(&persistent_gnt->node);
1263                         if (persistent_gnt->gref != GRANT_INVALID_REF) {
1264                                 gnttab_end_foreign_access(persistent_gnt->gref,
1265                                                           0, 0UL);
1266                                 rinfo->persistent_gnts_c--;
1267                         }
1268                         if (info->feature_persistent)
1269                                 __free_page(persistent_gnt->page);
1270                         kfree(persistent_gnt);
1271                 }
1272         }
1273         BUG_ON(rinfo->persistent_gnts_c != 0);
1274
1275         for (i = 0; i < BLK_RING_SIZE(info); i++) {
1276                 /*
1277                  * Clear persistent grants present in requests already
1278                  * on the shared ring
1279                  */
1280                 if (!rinfo->shadow[i].request)
1281                         goto free_shadow;
1282
1283                 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1284                        rinfo->shadow[i].req.u.indirect.nr_segments :
1285                        rinfo->shadow[i].req.u.rw.nr_segments;
1286                 for (j = 0; j < segs; j++) {
1287                         persistent_gnt = rinfo->shadow[i].grants_used[j];
1288                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1289                         if (info->feature_persistent)
1290                                 __free_page(persistent_gnt->page);
1291                         kfree(persistent_gnt);
1292                 }
1293
1294                 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1295                         /*
1296                          * If this is not an indirect operation don't try to
1297                          * free indirect segments
1298                          */
1299                         goto free_shadow;
1300
1301                 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1302                         persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1303                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1304                         __free_page(persistent_gnt->page);
1305                         kfree(persistent_gnt);
1306                 }
1307
1308 free_shadow:
1309                 kfree(rinfo->shadow[i].grants_used);
1310                 rinfo->shadow[i].grants_used = NULL;
1311                 kfree(rinfo->shadow[i].indirect_grants);
1312                 rinfo->shadow[i].indirect_grants = NULL;
1313                 kfree(rinfo->shadow[i].sg);
1314                 rinfo->shadow[i].sg = NULL;
1315         }
1316
1317         /* No more gnttab callback work. */
1318         gnttab_cancel_free_callback(&rinfo->callback);
1319
1320         /* Flush gnttab callback work. Must be done with no locks held. */
1321         flush_work(&rinfo->work);
1322
1323         /* Free resources associated with old device channel. */
1324         for (i = 0; i < info->nr_ring_pages; i++) {
1325                 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1326                         gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1327                         rinfo->ring_ref[i] = GRANT_INVALID_REF;
1328                 }
1329         }
1330         free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
1331         rinfo->ring.sring = NULL;
1332
1333         if (rinfo->irq)
1334                 unbind_from_irqhandler(rinfo->irq, rinfo);
1335         rinfo->evtchn = rinfo->irq = 0;
1336 }
1337
1338 static void blkif_free(struct blkfront_info *info, int suspend)
1339 {
1340         unsigned int i;
1341
1342         /* Prevent new requests being issued until we fix things up. */
1343         info->connected = suspend ?
1344                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1345         /* No more blkif_request(). */
1346         if (info->rq)
1347                 blk_mq_stop_hw_queues(info->rq);
1348
1349         for (i = 0; i < info->nr_rings; i++)
1350                 blkif_free_ring(&info->rinfo[i]);
1351
1352         kfree(info->rinfo);
1353         info->rinfo = NULL;
1354         info->nr_rings = 0;
1355 }
1356
1357 struct copy_from_grant {
1358         const struct blk_shadow *s;
1359         unsigned int grant_idx;
1360         unsigned int bvec_offset;
1361         char *bvec_data;
1362 };
1363
1364 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1365                                   unsigned int len, void *data)
1366 {
1367         struct copy_from_grant *info = data;
1368         char *shared_data;
1369         /* Convenient aliases */
1370         const struct blk_shadow *s = info->s;
1371
1372         shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1373
1374         memcpy(info->bvec_data + info->bvec_offset,
1375                shared_data + offset, len);
1376
1377         info->bvec_offset += len;
1378         info->grant_idx++;
1379
1380         kunmap_atomic(shared_data);
1381 }
1382
1383 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1384 {
1385         switch (rsp)
1386         {
1387         case BLKIF_RSP_OKAY:
1388                 return REQ_DONE;
1389         case BLKIF_RSP_EOPNOTSUPP:
1390                 return REQ_EOPNOTSUPP;
1391         case BLKIF_RSP_ERROR:
1392                 /* Fallthrough. */
1393         default:
1394                 return REQ_ERROR;
1395         }
1396 }
1397
1398 /*
1399  * Get the final status of the block request based on two ring response
1400  */
1401 static int blkif_get_final_status(enum blk_req_status s1,
1402                                   enum blk_req_status s2)
1403 {
1404         BUG_ON(s1 == REQ_WAITING);
1405         BUG_ON(s2 == REQ_WAITING);
1406
1407         if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1408                 return BLKIF_RSP_ERROR;
1409         else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1410                 return BLKIF_RSP_EOPNOTSUPP;
1411         return BLKIF_RSP_OKAY;
1412 }
1413
1414 static bool blkif_completion(unsigned long *id,
1415                              struct blkfront_ring_info *rinfo,
1416                              struct blkif_response *bret)
1417 {
1418         int i = 0;
1419         struct scatterlist *sg;
1420         int num_sg, num_grant;
1421         struct blkfront_info *info = rinfo->dev_info;
1422         struct blk_shadow *s = &rinfo->shadow[*id];
1423         struct copy_from_grant data = {
1424                 .grant_idx = 0,
1425         };
1426
1427         num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1428                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1429
1430         /* The I/O request may be split in two. */
1431         if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1432                 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1433
1434                 /* Keep the status of the current response in shadow. */
1435                 s->status = blkif_rsp_to_req_status(bret->status);
1436
1437                 /* Wait the second response if not yet here. */
1438                 if (s2->status == REQ_WAITING)
1439                         return false;
1440
1441                 bret->status = blkif_get_final_status(s->status,
1442                                                       s2->status);
1443
1444                 /*
1445                  * All the grants is stored in the first shadow in order
1446                  * to make the completion code simpler.
1447                  */
1448                 num_grant += s2->req.u.rw.nr_segments;
1449
1450                 /*
1451                  * The two responses may not come in order. Only the
1452                  * first request will store the scatter-gather list.
1453                  */
1454                 if (s2->num_sg != 0) {
1455                         /* Update "id" with the ID of the first response. */
1456                         *id = s->associated_id;
1457                         s = s2;
1458                 }
1459
1460                 /*
1461                  * We don't need anymore the second request, so recycling
1462                  * it now.
1463                  */
1464                 if (add_id_to_freelist(rinfo, s->associated_id))
1465                         WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1466                              info->gd->disk_name, s->associated_id);
1467         }
1468
1469         data.s = s;
1470         num_sg = s->num_sg;
1471
1472         if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1473                 for_each_sg(s->sg, sg, num_sg, i) {
1474                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1475
1476                         data.bvec_offset = sg->offset;
1477                         data.bvec_data = kmap_atomic(sg_page(sg));
1478
1479                         gnttab_foreach_grant_in_range(sg_page(sg),
1480                                                       sg->offset,
1481                                                       sg->length,
1482                                                       blkif_copy_from_grant,
1483                                                       &data);
1484
1485                         kunmap_atomic(data.bvec_data);
1486                 }
1487         }
1488         /* Add the persistent grant into the list of free grants */
1489         for (i = 0; i < num_grant; i++) {
1490                 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1491                         /*
1492                          * If the grant is still mapped by the backend (the
1493                          * backend has chosen to make this grant persistent)
1494                          * we add it at the head of the list, so it will be
1495                          * reused first.
1496                          */
1497                         if (!info->feature_persistent)
1498                                 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1499                                                      s->grants_used[i]->gref);
1500                         list_add(&s->grants_used[i]->node, &rinfo->grants);
1501                         rinfo->persistent_gnts_c++;
1502                 } else {
1503                         /*
1504                          * If the grant is not mapped by the backend we end the
1505                          * foreign access and add it to the tail of the list,
1506                          * so it will not be picked again unless we run out of
1507                          * persistent grants.
1508                          */
1509                         gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1510                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1511                         list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1512                 }
1513         }
1514         if (s->req.operation == BLKIF_OP_INDIRECT) {
1515                 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1516                         if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1517                                 if (!info->feature_persistent)
1518                                         pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1519                                                              s->indirect_grants[i]->gref);
1520                                 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1521                                 rinfo->persistent_gnts_c++;
1522                         } else {
1523                                 struct page *indirect_page;
1524
1525                                 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1526                                 /*
1527                                  * Add the used indirect page back to the list of
1528                                  * available pages for indirect grefs.
1529                                  */
1530                                 if (!info->feature_persistent) {
1531                                         indirect_page = s->indirect_grants[i]->page;
1532                                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
1533                                 }
1534                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1535                                 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1536                         }
1537                 }
1538         }
1539
1540         return true;
1541 }
1542
1543 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1544 {
1545         struct request *req;
1546         struct blkif_response *bret;
1547         RING_IDX i, rp;
1548         unsigned long flags;
1549         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1550         struct blkfront_info *info = rinfo->dev_info;
1551
1552         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1553                 return IRQ_HANDLED;
1554
1555         spin_lock_irqsave(&rinfo->ring_lock, flags);
1556  again:
1557         rp = rinfo->ring.sring->rsp_prod;
1558         rmb(); /* Ensure we see queued responses up to 'rp'. */
1559
1560         for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1561                 unsigned long id;
1562
1563                 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1564                 id   = bret->id;
1565                 /*
1566                  * The backend has messed up and given us an id that we would
1567                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1568                  * look in get_id_from_freelist.
1569                  */
1570                 if (id >= BLK_RING_SIZE(info)) {
1571                         WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1572                              info->gd->disk_name, op_name(bret->operation), id);
1573                         /* We can't safely get the 'struct request' as
1574                          * the id is busted. */
1575                         continue;
1576                 }
1577                 req  = rinfo->shadow[id].request;
1578
1579                 if (bret->operation != BLKIF_OP_DISCARD) {
1580                         /*
1581                          * We may need to wait for an extra response if the
1582                          * I/O request is split in 2
1583                          */
1584                         if (!blkif_completion(&id, rinfo, bret))
1585                                 continue;
1586                 }
1587
1588                 if (add_id_to_freelist(rinfo, id)) {
1589                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1590                              info->gd->disk_name, op_name(bret->operation), id);
1591                         continue;
1592                 }
1593
1594                 if (bret->status == BLKIF_RSP_OKAY)
1595                         blkif_req(req)->error = BLK_STS_OK;
1596                 else
1597                         blkif_req(req)->error = BLK_STS_IOERR;
1598
1599                 switch (bret->operation) {
1600                 case BLKIF_OP_DISCARD:
1601                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1602                                 struct request_queue *rq = info->rq;
1603                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1604                                            info->gd->disk_name, op_name(bret->operation));
1605                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1606                                 info->feature_discard = 0;
1607                                 info->feature_secdiscard = 0;
1608                                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1609                                 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1610                         }
1611                         break;
1612                 case BLKIF_OP_FLUSH_DISKCACHE:
1613                 case BLKIF_OP_WRITE_BARRIER:
1614                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1615                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1616                                        info->gd->disk_name, op_name(bret->operation));
1617                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1618                         }
1619                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1620                                      rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1621                                 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1622                                        info->gd->disk_name, op_name(bret->operation));
1623                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1624                         }
1625                         if (unlikely(blkif_req(req)->error)) {
1626                                 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1627                                         blkif_req(req)->error = BLK_STS_OK;
1628                                 info->feature_fua = 0;
1629                                 info->feature_flush = 0;
1630                                 xlvbd_flush(info);
1631                         }
1632                         /* fall through */
1633                 case BLKIF_OP_READ:
1634                 case BLKIF_OP_WRITE:
1635                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
1636                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1637                                         "request: %x\n", bret->status);
1638
1639                         break;
1640                 default:
1641                         BUG();
1642                 }
1643
1644                 blk_mq_complete_request(req);
1645         }
1646
1647         rinfo->ring.rsp_cons = i;
1648
1649         if (i != rinfo->ring.req_prod_pvt) {
1650                 int more_to_do;
1651                 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1652                 if (more_to_do)
1653                         goto again;
1654         } else
1655                 rinfo->ring.sring->rsp_event = i + 1;
1656
1657         kick_pending_request_queues_locked(rinfo);
1658
1659         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1660
1661         return IRQ_HANDLED;
1662 }
1663
1664
1665 static int setup_blkring(struct xenbus_device *dev,
1666                          struct blkfront_ring_info *rinfo)
1667 {
1668         struct blkif_sring *sring;
1669         int err, i;
1670         struct blkfront_info *info = rinfo->dev_info;
1671         unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1672         grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1673
1674         for (i = 0; i < info->nr_ring_pages; i++)
1675                 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1676
1677         sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1678                                                        get_order(ring_size));
1679         if (!sring) {
1680                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1681                 return -ENOMEM;
1682         }
1683         SHARED_RING_INIT(sring);
1684         FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1685
1686         err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1687         if (err < 0) {
1688                 free_pages((unsigned long)sring, get_order(ring_size));
1689                 rinfo->ring.sring = NULL;
1690                 goto fail;
1691         }
1692         for (i = 0; i < info->nr_ring_pages; i++)
1693                 rinfo->ring_ref[i] = gref[i];
1694
1695         err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1696         if (err)
1697                 goto fail;
1698
1699         err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1700                                         "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 /* Common code used when first setting up, and when resuming. */
1763 static int talk_to_blkback(struct xenbus_device *dev,
1764                            struct blkfront_info *info)
1765 {
1766         const char *message = NULL;
1767         struct xenbus_transaction xbt;
1768         int err;
1769         unsigned int i, max_page_order;
1770         unsigned int ring_page_order;
1771
1772         if (!info)
1773                 return -ENODEV;
1774
1775         max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1776                                               "max-ring-page-order", 0);
1777         ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1778         info->nr_ring_pages = 1 << ring_page_order;
1779
1780         err = negotiate_mq(info);
1781         if (err)
1782                 goto destroy_blkring;
1783
1784         for (i = 0; i < info->nr_rings; i++) {
1785                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1786
1787                 /* Create shared ring, alloc event channel. */
1788                 err = setup_blkring(dev, rinfo);
1789                 if (err)
1790                         goto destroy_blkring;
1791         }
1792
1793 again:
1794         err = xenbus_transaction_start(&xbt);
1795         if (err) {
1796                 xenbus_dev_fatal(dev, err, "starting transaction");
1797                 goto destroy_blkring;
1798         }
1799
1800         if (info->nr_ring_pages > 1) {
1801                 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1802                                     ring_page_order);
1803                 if (err) {
1804                         message = "writing ring-page-order";
1805                         goto abort_transaction;
1806                 }
1807         }
1808
1809         /* We already got the number of queues/rings in _probe */
1810         if (info->nr_rings == 1) {
1811                 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1812                 if (err)
1813                         goto destroy_blkring;
1814         } else {
1815                 char *path;
1816                 size_t pathsize;
1817
1818                 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1819                                     info->nr_rings);
1820                 if (err) {
1821                         message = "writing multi-queue-num-queues";
1822                         goto abort_transaction;
1823                 }
1824
1825                 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1826                 path = kmalloc(pathsize, GFP_KERNEL);
1827                 if (!path) {
1828                         err = -ENOMEM;
1829                         message = "ENOMEM while writing ring references";
1830                         goto abort_transaction;
1831                 }
1832
1833                 for (i = 0; i < info->nr_rings; i++) {
1834                         memset(path, 0, pathsize);
1835                         snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1836                         err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1837                         if (err) {
1838                                 kfree(path);
1839                                 goto destroy_blkring;
1840                         }
1841                 }
1842                 kfree(path);
1843         }
1844         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1845                             XEN_IO_PROTO_ABI_NATIVE);
1846         if (err) {
1847                 message = "writing protocol";
1848                 goto abort_transaction;
1849         }
1850         err = xenbus_printf(xbt, dev->nodename,
1851                             "feature-persistent", "%u", 1);
1852         if (err)
1853                 dev_warn(&dev->dev,
1854                          "writing persistent grants feature to xenbus");
1855
1856         err = xenbus_transaction_end(xbt, 0);
1857         if (err) {
1858                 if (err == -EAGAIN)
1859                         goto again;
1860                 xenbus_dev_fatal(dev, err, "completing transaction");
1861                 goto destroy_blkring;
1862         }
1863
1864         for (i = 0; i < info->nr_rings; i++) {
1865                 unsigned int j;
1866                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1867
1868                 for (j = 0; j < BLK_RING_SIZE(info); j++)
1869                         rinfo->shadow[j].req.u.rw.id = j + 1;
1870                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1871         }
1872         xenbus_switch_state(dev, XenbusStateInitialised);
1873
1874         return 0;
1875
1876  abort_transaction:
1877         xenbus_transaction_end(xbt, 1);
1878         if (message)
1879                 xenbus_dev_fatal(dev, err, "%s", message);
1880  destroy_blkring:
1881         blkif_free(info, 0);
1882
1883         kfree(info);
1884         dev_set_drvdata(&dev->dev, NULL);
1885
1886         return err;
1887 }
1888
1889 static int negotiate_mq(struct blkfront_info *info)
1890 {
1891         unsigned int backend_max_queues;
1892         unsigned int i;
1893
1894         BUG_ON(info->nr_rings);
1895
1896         /* Check if backend supports multiple queues. */
1897         backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1898                                                   "multi-queue-max-queues", 1);
1899         info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1900         /* We need at least one ring. */
1901         if (!info->nr_rings)
1902                 info->nr_rings = 1;
1903
1904         info->rinfo = kcalloc(info->nr_rings,
1905                               sizeof(struct blkfront_ring_info),
1906                               GFP_KERNEL);
1907         if (!info->rinfo) {
1908                 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1909                 return -ENOMEM;
1910         }
1911
1912         for (i = 0; i < info->nr_rings; i++) {
1913                 struct blkfront_ring_info *rinfo;
1914
1915                 rinfo = &info->rinfo[i];
1916                 INIT_LIST_HEAD(&rinfo->indirect_pages);
1917                 INIT_LIST_HEAD(&rinfo->grants);
1918                 rinfo->dev_info = info;
1919                 INIT_WORK(&rinfo->work, blkif_restart_queue);
1920                 spin_lock_init(&rinfo->ring_lock);
1921         }
1922         return 0;
1923 }
1924 /**
1925  * Entry point to this code when a new device is created.  Allocate the basic
1926  * structures and the ring buffer for communication with the backend, and
1927  * inform the backend of the appropriate details for those.  Switch to
1928  * Initialised state.
1929  */
1930 static int blkfront_probe(struct xenbus_device *dev,
1931                           const struct xenbus_device_id *id)
1932 {
1933         int err, vdevice;
1934         struct blkfront_info *info;
1935
1936         /* FIXME: Use dynamic device id if this is not set. */
1937         err = xenbus_scanf(XBT_NIL, dev->nodename,
1938                            "virtual-device", "%i", &vdevice);
1939         if (err != 1) {
1940                 /* go looking in the extended area instead */
1941                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1942                                    "%i", &vdevice);
1943                 if (err != 1) {
1944                         xenbus_dev_fatal(dev, err, "reading virtual-device");
1945                         return err;
1946                 }
1947         }
1948
1949         if (xen_hvm_domain()) {
1950                 char *type;
1951                 int len;
1952                 /* no unplug has been done: do not hook devices != xen vbds */
1953                 if (xen_has_pv_and_legacy_disk_devices()) {
1954                         int major;
1955
1956                         if (!VDEV_IS_EXTENDED(vdevice))
1957                                 major = BLKIF_MAJOR(vdevice);
1958                         else
1959                                 major = XENVBD_MAJOR;
1960
1961                         if (major != XENVBD_MAJOR) {
1962                                 printk(KERN_INFO
1963                                                 "%s: HVM does not support vbd %d as xen block device\n",
1964                                                 __func__, vdevice);
1965                                 return -ENODEV;
1966                         }
1967                 }
1968                 /* do not create a PV cdrom device if we are an HVM guest */
1969                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1970                 if (IS_ERR(type))
1971                         return -ENODEV;
1972                 if (strncmp(type, "cdrom", 5) == 0) {
1973                         kfree(type);
1974                         return -ENODEV;
1975                 }
1976                 kfree(type);
1977         }
1978         info = kzalloc(sizeof(*info), GFP_KERNEL);
1979         if (!info) {
1980                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1981                 return -ENOMEM;
1982         }
1983
1984         info->xbdev = dev;
1985
1986         mutex_init(&info->mutex);
1987         info->vdevice = vdevice;
1988         info->connected = BLKIF_STATE_DISCONNECTED;
1989
1990         /* Front end dir is a number, which is used as the id. */
1991         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
1992         dev_set_drvdata(&dev->dev, info);
1993
1994         return 0;
1995 }
1996
1997 static int blkif_recover(struct blkfront_info *info)
1998 {
1999         unsigned int r_index;
2000         struct request *req, *n;
2001         int rc;
2002         struct bio *bio;
2003         unsigned int segs;
2004
2005         blkfront_gather_backend_features(info);
2006         /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2007         blkif_set_queue_limits(info);
2008         segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2009         blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2010
2011         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2012                 struct blkfront_ring_info *rinfo = &info->rinfo[r_index];
2013
2014                 rc = blkfront_setup_indirect(rinfo);
2015                 if (rc)
2016                         return rc;
2017         }
2018         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2019
2020         /* Now safe for us to use the shared ring */
2021         info->connected = BLKIF_STATE_CONNECTED;
2022
2023         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2024                 struct blkfront_ring_info *rinfo;
2025
2026                 rinfo = &info->rinfo[r_index];
2027                 /* Kick any other new requests queued since we resumed */
2028                 kick_pending_request_queues(rinfo);
2029         }
2030
2031         list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2032                 /* Requeue pending requests (flush or discard) */
2033                 list_del_init(&req->queuelist);
2034                 BUG_ON(req->nr_phys_segments > segs);
2035                 blk_mq_requeue_request(req, false);
2036         }
2037         blk_mq_start_stopped_hw_queues(info->rq, true);
2038         blk_mq_kick_requeue_list(info->rq);
2039
2040         while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2041                 /* Traverse the list of pending bios and re-queue them */
2042                 submit_bio(bio);
2043         }
2044
2045         return 0;
2046 }
2047
2048 /**
2049  * We are reconnecting to the backend, due to a suspend/resume, or a backend
2050  * driver restart.  We tear down our blkif structure and recreate it, but
2051  * leave the device-layer structures intact so that this is transparent to the
2052  * rest of the kernel.
2053  */
2054 static int blkfront_resume(struct xenbus_device *dev)
2055 {
2056         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2057         int err = 0;
2058         unsigned int i, j;
2059
2060         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2061
2062         bio_list_init(&info->bio_list);
2063         INIT_LIST_HEAD(&info->requests);
2064         for (i = 0; i < info->nr_rings; i++) {
2065                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2066                 struct bio_list merge_bio;
2067                 struct blk_shadow *shadow = rinfo->shadow;
2068
2069                 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2070                         /* Not in use? */
2071                         if (!shadow[j].request)
2072                                 continue;
2073
2074                         /*
2075                          * Get the bios in the request so we can re-queue them.
2076                          */
2077                         if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2078                             req_op(shadow[j].request) == REQ_OP_DISCARD ||
2079                             req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2080                             shadow[j].request->cmd_flags & REQ_FUA) {
2081                                 /*
2082                                  * Flush operations don't contain bios, so
2083                                  * we need to requeue the whole request
2084                                  *
2085                                  * XXX: but this doesn't make any sense for a
2086                                  * write with the FUA flag set..
2087                                  */
2088                                 list_add(&shadow[j].request->queuelist, &info->requests);
2089                                 continue;
2090                         }
2091                         merge_bio.head = shadow[j].request->bio;
2092                         merge_bio.tail = shadow[j].request->biotail;
2093                         bio_list_merge(&info->bio_list, &merge_bio);
2094                         shadow[j].request->bio = NULL;
2095                         blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2096                 }
2097         }
2098
2099         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2100
2101         err = talk_to_blkback(dev, info);
2102         if (!err)
2103                 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2104
2105         /*
2106          * We have to wait for the backend to switch to
2107          * connected state, since we want to read which
2108          * features it supports.
2109          */
2110
2111         return err;
2112 }
2113
2114 static void blkfront_closing(struct blkfront_info *info)
2115 {
2116         struct xenbus_device *xbdev = info->xbdev;
2117         struct block_device *bdev = NULL;
2118
2119         mutex_lock(&info->mutex);
2120
2121         if (xbdev->state == XenbusStateClosing) {
2122                 mutex_unlock(&info->mutex);
2123                 return;
2124         }
2125
2126         if (info->gd)
2127                 bdev = bdget_disk(info->gd, 0);
2128
2129         mutex_unlock(&info->mutex);
2130
2131         if (!bdev) {
2132                 xenbus_frontend_closed(xbdev);
2133                 return;
2134         }
2135
2136         mutex_lock(&bdev->bd_mutex);
2137
2138         if (bdev->bd_openers) {
2139                 xenbus_dev_error(xbdev, -EBUSY,
2140                                  "Device in use; refusing to close");
2141                 xenbus_switch_state(xbdev, XenbusStateClosing);
2142         } else {
2143                 xlvbd_release_gendisk(info);
2144                 xenbus_frontend_closed(xbdev);
2145         }
2146
2147         mutex_unlock(&bdev->bd_mutex);
2148         bdput(bdev);
2149 }
2150
2151 static void blkfront_setup_discard(struct blkfront_info *info)
2152 {
2153         int err;
2154         unsigned int discard_granularity;
2155         unsigned int discard_alignment;
2156
2157         info->feature_discard = 1;
2158         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2159                 "discard-granularity", "%u", &discard_granularity,
2160                 "discard-alignment", "%u", &discard_alignment,
2161                 NULL);
2162         if (!err) {
2163                 info->discard_granularity = discard_granularity;
2164                 info->discard_alignment = discard_alignment;
2165         }
2166         info->feature_secdiscard =
2167                 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2168                                        0);
2169 }
2170
2171 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2172 {
2173         unsigned int psegs, grants;
2174         int err, i;
2175         struct blkfront_info *info = rinfo->dev_info;
2176
2177         if (info->max_indirect_segments == 0) {
2178                 if (!HAS_EXTRA_REQ)
2179                         grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2180                 else {
2181                         /*
2182                          * When an extra req is required, the maximum
2183                          * grants supported is related to the size of the
2184                          * Linux block segment.
2185                          */
2186                         grants = GRANTS_PER_PSEG;
2187                 }
2188         }
2189         else
2190                 grants = info->max_indirect_segments;
2191         psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2192
2193         err = fill_grant_buffer(rinfo,
2194                                 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2195         if (err)
2196                 goto out_of_memory;
2197
2198         if (!info->feature_persistent && info->max_indirect_segments) {
2199                 /*
2200                  * We are using indirect descriptors but not persistent
2201                  * grants, we need to allocate a set of pages that can be
2202                  * used for mapping indirect grefs
2203                  */
2204                 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2205
2206                 BUG_ON(!list_empty(&rinfo->indirect_pages));
2207                 for (i = 0; i < num; i++) {
2208                         struct page *indirect_page = alloc_page(GFP_NOIO);
2209                         if (!indirect_page)
2210                                 goto out_of_memory;
2211                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
2212                 }
2213         }
2214
2215         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2216                 rinfo->shadow[i].grants_used =
2217                         kcalloc(grants,
2218                                 sizeof(rinfo->shadow[i].grants_used[0]),
2219                                 GFP_NOIO);
2220                 rinfo->shadow[i].sg = kcalloc(psegs,
2221                                               sizeof(rinfo->shadow[i].sg[0]),
2222                                               GFP_NOIO);
2223                 if (info->max_indirect_segments)
2224                         rinfo->shadow[i].indirect_grants =
2225                                 kcalloc(INDIRECT_GREFS(grants),
2226                                         sizeof(rinfo->shadow[i].indirect_grants[0]),
2227                                         GFP_NOIO);
2228                 if ((rinfo->shadow[i].grants_used == NULL) ||
2229                         (rinfo->shadow[i].sg == NULL) ||
2230                      (info->max_indirect_segments &&
2231                      (rinfo->shadow[i].indirect_grants == NULL)))
2232                         goto out_of_memory;
2233                 sg_init_table(rinfo->shadow[i].sg, psegs);
2234         }
2235
2236
2237         return 0;
2238
2239 out_of_memory:
2240         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2241                 kfree(rinfo->shadow[i].grants_used);
2242                 rinfo->shadow[i].grants_used = NULL;
2243                 kfree(rinfo->shadow[i].sg);
2244                 rinfo->shadow[i].sg = NULL;
2245                 kfree(rinfo->shadow[i].indirect_grants);
2246                 rinfo->shadow[i].indirect_grants = NULL;
2247         }
2248         if (!list_empty(&rinfo->indirect_pages)) {
2249                 struct page *indirect_page, *n;
2250                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2251                         list_del(&indirect_page->lru);
2252                         __free_page(indirect_page);
2253                 }
2254         }
2255         return -ENOMEM;
2256 }
2257
2258 /*
2259  * Gather all backend feature-*
2260  */
2261 static void blkfront_gather_backend_features(struct blkfront_info *info)
2262 {
2263         unsigned int indirect_segments;
2264
2265         info->feature_flush = 0;
2266         info->feature_fua = 0;
2267
2268         /*
2269          * If there's no "feature-barrier" defined, then it means
2270          * we're dealing with a very old backend which writes
2271          * synchronously; nothing to do.
2272          *
2273          * If there are barriers, then we use flush.
2274          */
2275         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2276                 info->feature_flush = 1;
2277                 info->feature_fua = 1;
2278         }
2279
2280         /*
2281          * And if there is "feature-flush-cache" use that above
2282          * barriers.
2283          */
2284         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2285                                  0)) {
2286                 info->feature_flush = 1;
2287                 info->feature_fua = 0;
2288         }
2289
2290         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2291                 blkfront_setup_discard(info);
2292
2293         info->feature_persistent =
2294                 !!xenbus_read_unsigned(info->xbdev->otherend,
2295                                        "feature-persistent", 0);
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
2306 /*
2307  * Invoked when the backend is finally 'ready' (and has told produced
2308  * the details about the physical device - #sectors, size, etc).
2309  */
2310 static void blkfront_connect(struct blkfront_info *info)
2311 {
2312         unsigned long long sectors;
2313         unsigned long sector_size;
2314         unsigned int physical_sector_size;
2315         unsigned int binfo;
2316         char *envp[] = { "RESIZE=1", NULL };
2317         int err, i;
2318
2319         switch (info->connected) {
2320         case BLKIF_STATE_CONNECTED:
2321                 /*
2322                  * Potentially, the back-end may be signalling
2323                  * a capacity change; update the capacity.
2324                  */
2325                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2326                                    "sectors", "%Lu", &sectors);
2327                 if (XENBUS_EXIST_ERR(err))
2328                         return;
2329                 printk(KERN_INFO "Setting capacity to %Lu\n",
2330                        sectors);
2331                 set_capacity(info->gd, sectors);
2332                 revalidate_disk(info->gd);
2333                 kobject_uevent_env(&disk_to_dev(info->gd)->kobj,
2334                                    KOBJ_CHANGE, envp);
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", &binfo,
2357                             "sector-size", "%lu", &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          * physcial-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         physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2372                                                     "physical-sector-size",
2373                                                     sector_size);
2374         blkfront_gather_backend_features(info);
2375         for (i = 0; i < info->nr_rings; i++) {
2376                 err = blkfront_setup_indirect(&info->rinfo[i]);
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, binfo, sector_size,
2386                                   physical_sector_size);
2387         if (err) {
2388                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2389                                  info->xbdev->otherend);
2390                 goto fail;
2391         }
2392
2393         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2394
2395         /* Kick pending requests. */
2396         info->connected = BLKIF_STATE_CONNECTED;
2397         for (i = 0; i < info->nr_rings; i++)
2398                 kick_pending_request_queues(&info->rinfo[i]);
2399
2400         device_add_disk(&info->xbdev->dev, info->gd);
2401
2402         info->is_ready = 1;
2403         return;
2404
2405 fail:
2406         blkif_free(info, 0);
2407         return;
2408 }
2409
2410 /**
2411  * Callback received when the backend's state changes.
2412  */
2413 static void blkback_changed(struct xenbus_device *dev,
2414                             enum xenbus_state backend_state)
2415 {
2416         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2417
2418         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2419
2420         switch (backend_state) {
2421         case XenbusStateInitWait:
2422                 if (dev->state != XenbusStateInitialising)
2423                         break;
2424                 if (talk_to_blkback(dev, info))
2425                         break;
2426         case XenbusStateInitialising:
2427         case XenbusStateInitialised:
2428         case XenbusStateReconfiguring:
2429         case XenbusStateReconfigured:
2430         case XenbusStateUnknown:
2431                 break;
2432
2433         case XenbusStateConnected:
2434                 /*
2435                  * talk_to_blkback sets state to XenbusStateInitialised
2436                  * and blkfront_connect sets it to XenbusStateConnected
2437                  * (if connection went OK).
2438                  *
2439                  * If the backend (or toolstack) decides to poke at backend
2440                  * state (and re-trigger the watch by setting the state repeatedly
2441                  * to XenbusStateConnected (4)) we need to deal with this.
2442                  * This is allowed as this is used to communicate to the guest
2443                  * that the size of disk has changed!
2444                  */
2445                 if ((dev->state != XenbusStateInitialised) &&
2446                     (dev->state != XenbusStateConnected)) {
2447                         if (talk_to_blkback(dev, info))
2448                                 break;
2449                 }
2450
2451                 blkfront_connect(info);
2452                 break;
2453
2454         case XenbusStateClosed:
2455                 if (dev->state == XenbusStateClosed)
2456                         break;
2457                 /* fall through */
2458         case XenbusStateClosing:
2459                 if (info)
2460                         blkfront_closing(info);
2461                 break;
2462         }
2463 }
2464
2465 static int blkfront_remove(struct xenbus_device *xbdev)
2466 {
2467         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2468         struct block_device *bdev = NULL;
2469         struct gendisk *disk;
2470
2471         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2472
2473         blkif_free(info, 0);
2474
2475         mutex_lock(&info->mutex);
2476
2477         disk = info->gd;
2478         if (disk)
2479                 bdev = bdget_disk(disk, 0);
2480
2481         info->xbdev = NULL;
2482         mutex_unlock(&info->mutex);
2483
2484         if (!bdev) {
2485                 kfree(info);
2486                 return 0;
2487         }
2488
2489         /*
2490          * The xbdev was removed before we reached the Closed
2491          * state. See if it's safe to remove the disk. If the bdev
2492          * isn't closed yet, we let release take care of it.
2493          */
2494
2495         mutex_lock(&bdev->bd_mutex);
2496         info = disk->private_data;
2497
2498         dev_warn(disk_to_dev(disk),
2499                  "%s was hot-unplugged, %d stale handles\n",
2500                  xbdev->nodename, bdev->bd_openers);
2501
2502         if (info && !bdev->bd_openers) {
2503                 xlvbd_release_gendisk(info);
2504                 disk->private_data = NULL;
2505                 kfree(info);
2506         }
2507
2508         mutex_unlock(&bdev->bd_mutex);
2509         bdput(bdev);
2510
2511         return 0;
2512 }
2513
2514 static int blkfront_is_ready(struct xenbus_device *dev)
2515 {
2516         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2517
2518         return info->is_ready && info->xbdev;
2519 }
2520
2521 static int blkif_open(struct block_device *bdev, fmode_t mode)
2522 {
2523         struct gendisk *disk = bdev->bd_disk;
2524         struct blkfront_info *info;
2525         int err = 0;
2526
2527         mutex_lock(&blkfront_mutex);
2528
2529         info = disk->private_data;
2530         if (!info) {
2531                 /* xbdev gone */
2532                 err = -ERESTARTSYS;
2533                 goto out;
2534         }
2535
2536         mutex_lock(&info->mutex);
2537
2538         if (!info->gd)
2539                 /* xbdev is closed */
2540                 err = -ERESTARTSYS;
2541
2542         mutex_unlock(&info->mutex);
2543
2544 out:
2545         mutex_unlock(&blkfront_mutex);
2546         return err;
2547 }
2548
2549 static void blkif_release(struct gendisk *disk, fmode_t mode)
2550 {
2551         struct blkfront_info *info = disk->private_data;
2552         struct block_device *bdev;
2553         struct xenbus_device *xbdev;
2554
2555         mutex_lock(&blkfront_mutex);
2556
2557         bdev = bdget_disk(disk, 0);
2558
2559         if (!bdev) {
2560                 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2561                 goto out_mutex;
2562         }
2563         if (bdev->bd_openers)
2564                 goto out;
2565
2566         /*
2567          * Check if we have been instructed to close. We will have
2568          * deferred this request, because the bdev was still open.
2569          */
2570
2571         mutex_lock(&info->mutex);
2572         xbdev = info->xbdev;
2573
2574         if (xbdev && xbdev->state == XenbusStateClosing) {
2575                 /* pending switch to state closed */
2576                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2577                 xlvbd_release_gendisk(info);
2578                 xenbus_frontend_closed(info->xbdev);
2579         }
2580
2581         mutex_unlock(&info->mutex);
2582
2583         if (!xbdev) {
2584                 /* sudden device removal */
2585                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2586                 xlvbd_release_gendisk(info);
2587                 disk->private_data = NULL;
2588                 kfree(info);
2589         }
2590
2591 out:
2592         bdput(bdev);
2593 out_mutex:
2594         mutex_unlock(&blkfront_mutex);
2595 }
2596
2597 static const struct block_device_operations xlvbd_block_fops =
2598 {
2599         .owner = THIS_MODULE,
2600         .open = blkif_open,
2601         .release = blkif_release,
2602         .getgeo = blkif_getgeo,
2603         .ioctl = blkif_ioctl,
2604 };
2605
2606
2607 static const struct xenbus_device_id blkfront_ids[] = {
2608         { "vbd" },
2609         { "" }
2610 };
2611
2612 static struct xenbus_driver blkfront_driver = {
2613         .ids  = blkfront_ids,
2614         .probe = blkfront_probe,
2615         .remove = blkfront_remove,
2616         .resume = blkfront_resume,
2617         .otherend_changed = blkback_changed,
2618         .is_ready = blkfront_is_ready,
2619 };
2620
2621 static int __init xlblk_init(void)
2622 {
2623         int ret;
2624         int nr_cpus = num_online_cpus();
2625
2626         if (!xen_domain())
2627                 return -ENODEV;
2628
2629         if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2630                 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2631
2632         if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2633                 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2634                         xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2635                 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2636         }
2637
2638         if (xen_blkif_max_queues > nr_cpus) {
2639                 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2640                         xen_blkif_max_queues, nr_cpus);
2641                 xen_blkif_max_queues = nr_cpus;
2642         }
2643
2644         if (!xen_has_pv_disk_devices())
2645                 return -ENODEV;
2646
2647         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2648                 printk(KERN_WARNING "xen_blk: can't get major %d with name %s\n",
2649                        XENVBD_MAJOR, DEV_NAME);
2650                 return -ENODEV;
2651         }
2652
2653         ret = xenbus_register_frontend(&blkfront_driver);
2654         if (ret) {
2655                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2656                 return ret;
2657         }
2658
2659         return 0;
2660 }
2661 module_init(xlblk_init);
2662
2663
2664 static void __exit xlblk_exit(void)
2665 {
2666         xenbus_unregister_driver(&blkfront_driver);
2667         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2668         kfree(minors);
2669 }
2670 module_exit(xlblk_exit);
2671
2672 MODULE_DESCRIPTION("Xen virtual block device frontend");
2673 MODULE_LICENSE("GPL");
2674 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2675 MODULE_ALIAS("xen:vbd");
2676 MODULE_ALIAS("xenblk");