drivers/block/xen-blkfront.c

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This source file includes following definitions.
get_id_from_freelist
add_id_to_freelist
fill_grant_buffer
get_free_grant
grant_foreign_access
get_grant
get_indirect_grant
op_name
xlbd_reserve_minors
xlbd_release_minors
blkif_restart_queue_callback
blkif_getgeo
blkif_ioctl
blkif_ring_get_request
blkif_queue_discard_req
blkif_setup_rw_req_grant
blkif_setup_extra_req
blkif_queue_rw_req
blkif_queue_request
flush_requests
blkif_request_flush_invalid
blkif_queue_rq
blkif_complete_rq
blkif_set_queue_limits
xlvbd_init_blk_queue
flush_info
xlvbd_flush
xen_translate_vdev
encode_disk_name
xlvbd_alloc_gendisk
xlvbd_release_gendisk
kick_pending_request_queues_locked
kick_pending_request_queues
blkif_restart_queue
blkif_free_ring
blkif_free
blkif_copy_from_grant
blkif_rsp_to_req_status
blkif_get_final_status
blkif_completion
blkif_interrupt
setup_blkring
write_per_ring_nodes
free_info
talk_to_blkback
negotiate_mq
blkfront_probe
blkif_recover
blkfront_resume
blkfront_closing
blkfront_setup_discard
blkfront_setup_indirect
blkfront_gather_backend_features
blkfront_connect
blkback_changed
blkfront_remove
blkfront_is_ready
blkif_open
blkif_release
purge_persistent_grants
blkfront_delay_work
xlblk_init
xlblk_exit
   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 #include <linux/workqueue.h>
  50 #include <linux/sched/mm.h>
  51 
  52 #include <xen/xen.h>
  53 #include <xen/xenbus.h>
  54 #include <xen/grant_table.h>
  55 #include <xen/events.h>
  56 #include <xen/page.h>
  57 #include <xen/platform_pci.h>
  58 
  59 #include <xen/interface/grant_table.h>
  60 #include <xen/interface/io/blkif.h>
  61 #include <xen/interface/io/protocols.h>
  62 
  63 #include <asm/xen/hypervisor.h>
  64 
  65 /*
  66  * The minimal size of segment supported by the block framework is PAGE_SIZE.
  67  * When Linux is using a different page size than Xen, it may not be possible
  68  * to put all the data in a single segment.
  69  * This can happen when the backend doesn't support indirect descriptor and
  70  * therefore the maximum amount of data that a request can carry is
  71  * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE = 44KB
  72  *
  73  * Note that we only support one extra request. So the Linux page size
  74  * should be <= ( 2 * BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) =
  75  * 88KB.
  76  */
  77 #define HAS_EXTRA_REQ (BLKIF_MAX_SEGMENTS_PER_REQUEST < XEN_PFN_PER_PAGE)
  78 
  79 enum blkif_state {
  80         BLKIF_STATE_DISCONNECTED,
  81         BLKIF_STATE_CONNECTED,
  82         BLKIF_STATE_SUSPENDED,
  83 };
  84 
  85 struct grant {
  86         grant_ref_t gref;
  87         struct page *page;
  88         struct list_head node;
  89 };
  90 
  91 enum blk_req_status {
  92         REQ_WAITING,
  93         REQ_DONE,
  94         REQ_ERROR,
  95         REQ_EOPNOTSUPP,
  96 };
  97 
  98 struct blk_shadow {
  99         struct blkif_request req;
 100         struct request *request;
 101         struct grant **grants_used;
 102         struct grant **indirect_grants;
 103         struct scatterlist *sg;
 104         unsigned int num_sg;
 105         enum blk_req_status status;
 106 
 107         #define NO_ASSOCIATED_ID ~0UL
 108         /*
 109          * Id of the sibling if we ever need 2 requests when handling a
 110          * block I/O request
 111          */
 112         unsigned long associated_id;
 113 };
 114 
 115 struct blkif_req {
 116         blk_status_t    error;
 117 };
 118 
 119 static inline struct blkif_req *blkif_req(struct request *rq)
 120 {
 121         return blk_mq_rq_to_pdu(rq);
 122 }
 123 
 124 static DEFINE_MUTEX(blkfront_mutex);
 125 static const struct block_device_operations xlvbd_block_fops;
 126 static struct delayed_work blkfront_work;
 127 static LIST_HEAD(info_list);
 128 
 129 /*
 130  * Maximum number of segments in indirect requests, the actual value used by
 131  * the frontend driver is the minimum of this value and the value provided
 132  * by the backend driver.
 133  */
 134 
 135 static unsigned int xen_blkif_max_segments = 32;
 136 module_param_named(max_indirect_segments, xen_blkif_max_segments, uint, 0444);
 137 MODULE_PARM_DESC(max_indirect_segments,
 138                  "Maximum amount of segments in indirect requests (default is 32)");
 139 
 140 static unsigned int xen_blkif_max_queues = 4;
 141 module_param_named(max_queues, xen_blkif_max_queues, uint, 0444);
 142 MODULE_PARM_DESC(max_queues, "Maximum number of hardware queues/rings used per virtual disk");
 143 
 144 /*
 145  * Maximum order of pages to be used for the shared ring between front and
 146  * backend, 4KB page granularity is used.
 147  */
 148 static unsigned int xen_blkif_max_ring_order;
 149 module_param_named(max_ring_page_order, xen_blkif_max_ring_order, int, 0444);
 150 MODULE_PARM_DESC(max_ring_page_order, "Maximum order of pages to be used for the shared ring");
 151 
 152 #define BLK_RING_SIZE(info)     \
 153         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * (info)->nr_ring_pages)
 154 
 155 #define BLK_MAX_RING_SIZE       \
 156         __CONST_RING_SIZE(blkif, XEN_PAGE_SIZE * XENBUS_MAX_RING_GRANTS)
 157 
 158 /*
 159  * ring-ref%u i=(-1UL) would take 11 characters + 'ring-ref' is 8, so 19
 160  * characters are enough. Define to 20 to keep consistent with backend.
 161  */
 162 #define RINGREF_NAME_LEN (20)
 163 /*
 164  * queue-%u would take 7 + 10(UINT_MAX) = 17 characters.
 165  */
 166 #define QUEUE_NAME_LEN (17)
 167 
 168 /*
 169  *  Per-ring info.
 170  *  Every blkfront device can associate with one or more blkfront_ring_info,
 171  *  depending on how many hardware queues/rings to be used.
 172  */
 173 struct blkfront_ring_info {
 174         /* Lock to protect data in every ring buffer. */
 175         spinlock_t ring_lock;
 176         struct blkif_front_ring ring;
 177         unsigned int ring_ref[XENBUS_MAX_RING_GRANTS];
 178         unsigned int evtchn, irq;
 179         struct work_struct work;
 180         struct gnttab_free_callback callback;
 181         struct blk_shadow shadow[BLK_MAX_RING_SIZE];
 182         struct list_head indirect_pages;
 183         struct list_head grants;
 184         unsigned int persistent_gnts_c;
 185         unsigned long shadow_free;
 186         struct blkfront_info *dev_info;
 187 };
 188 
 189 /*
 190  * We have one of these per vbd, whether ide, scsi or 'other'.  They
 191  * hang in private_data off the gendisk structure. We may end up
 192  * putting all kinds of interesting stuff here :-)
 193  */
 194 struct blkfront_info
 195 {
 196         struct mutex mutex;
 197         struct xenbus_device *xbdev;
 198         struct gendisk *gd;
 199         u16 sector_size;
 200         unsigned int physical_sector_size;
 201         int vdevice;
 202         blkif_vdev_t handle;
 203         enum blkif_state connected;
 204         /* Number of pages per ring buffer. */
 205         unsigned int nr_ring_pages;
 206         struct request_queue *rq;
 207         unsigned int feature_flush:1;
 208         unsigned int feature_fua:1;
 209         unsigned int feature_discard:1;
 210         unsigned int feature_secdiscard:1;
 211         unsigned int feature_persistent:1;
 212         unsigned int discard_granularity;
 213         unsigned int discard_alignment;
 214         /* Number of 4KB segments handled */
 215         unsigned int max_indirect_segments;
 216         int is_ready;
 217         struct blk_mq_tag_set tag_set;
 218         struct blkfront_ring_info *rinfo;
 219         unsigned int nr_rings;
 220         /* Save uncomplete reqs and bios for migration. */
 221         struct list_head requests;
 222         struct bio_list bio_list;
 223         struct list_head info_list;
 224 };
 225 
 226 static unsigned int nr_minors;
 227 static unsigned long *minors;
 228 static DEFINE_SPINLOCK(minor_lock);
 229 
 230 #define GRANT_INVALID_REF       0
 231 
 232 #define PARTS_PER_DISK          16
 233 #define PARTS_PER_EXT_DISK      256
 234 
 235 #define BLKIF_MAJOR(dev) ((dev)>>8)
 236 #define BLKIF_MINOR(dev) ((dev) & 0xff)
 237 
 238 #define EXT_SHIFT 28
 239 #define EXTENDED (1<<EXT_SHIFT)
 240 #define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))
 241 #define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))
 242 #define EMULATED_HD_DISK_MINOR_OFFSET (0)
 243 #define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)
 244 #define EMULATED_SD_DISK_MINOR_OFFSET (0)
 245 #define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_SD_DISK_MINOR_OFFSET / 256)
 246 
 247 #define DEV_NAME        "xvd"   /* name in /dev */
 248 
 249 /*
 250  * Grants are always the same size as a Xen page (i.e 4KB).
 251  * A physical segment is always the same size as a Linux page.
 252  * Number of grants per physical segment
 253  */
 254 #define GRANTS_PER_PSEG (PAGE_SIZE / XEN_PAGE_SIZE)
 255 
 256 #define GRANTS_PER_INDIRECT_FRAME \
 257         (XEN_PAGE_SIZE / sizeof(struct blkif_request_segment))
 258 
 259 #define INDIRECT_GREFS(_grants)         \
 260         DIV_ROUND_UP(_grants, GRANTS_PER_INDIRECT_FRAME)
 261 
 262 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo);
 263 static void blkfront_gather_backend_features(struct blkfront_info *info);
 264 static int negotiate_mq(struct blkfront_info *info);
 265 
 266 static int get_id_from_freelist(struct blkfront_ring_info *rinfo)
 267 {
 268         unsigned long free = rinfo->shadow_free;
 269 
 270         BUG_ON(free >= BLK_RING_SIZE(rinfo->dev_info));
 271         rinfo->shadow_free = rinfo->shadow[free].req.u.rw.id;
 272         rinfo->shadow[free].req.u.rw.id = 0x0fffffee; /* debug */
 273         return free;
 274 }
 275 
 276 static int add_id_to_freelist(struct blkfront_ring_info *rinfo,
 277                               unsigned long id)
 278 {
 279         if (rinfo->shadow[id].req.u.rw.id != id)
 280                 return -EINVAL;
 281         if (rinfo->shadow[id].request == NULL)
 282                 return -EINVAL;
 283         rinfo->shadow[id].req.u.rw.id  = rinfo->shadow_free;
 284         rinfo->shadow[id].request = NULL;
 285         rinfo->shadow_free = id;
 286         return 0;
 287 }
 288 
 289 static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 290 {
 291         struct blkfront_info *info = rinfo->dev_info;
 292         struct page *granted_page;
 293         struct grant *gnt_list_entry, *n;
 294         int i = 0;
 295 
 296         while (i < num) {
 297                 gnt_list_entry = kzalloc(sizeof(struct grant), GFP_NOIO);
 298                 if (!gnt_list_entry)
 299                         goto out_of_memory;
 300 
 301                 if (info->feature_persistent) {
 302                         granted_page = alloc_page(GFP_NOIO);
 303                         if (!granted_page) {
 304                                 kfree(gnt_list_entry);
 305                                 goto out_of_memory;
 306                         }
 307                         gnt_list_entry->page = granted_page;
 308                 }
 309 
 310                 gnt_list_entry->gref = GRANT_INVALID_REF;
 311                 list_add(&gnt_list_entry->node, &rinfo->grants);
 312                 i++;
 313         }
 314 
 315         return 0;
 316 
 317 out_of_memory:
 318         list_for_each_entry_safe(gnt_list_entry, n,
 319                                  &rinfo->grants, node) {
 320                 list_del(&gnt_list_entry->node);
 321                 if (info->feature_persistent)
 322                         __free_page(gnt_list_entry->page);
 323                 kfree(gnt_list_entry);
 324                 i--;
 325         }
 326         BUG_ON(i != 0);
 327         return -ENOMEM;
 328 }
 329 
 330 static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
 331 {
 332         struct grant *gnt_list_entry;
 333 
 334         BUG_ON(list_empty(&rinfo->grants));
 335         gnt_list_entry = list_first_entry(&rinfo->grants, struct grant,
 336                                           node);
 337         list_del(&gnt_list_entry->node);
 338 
 339         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 340                 rinfo->persistent_gnts_c--;
 341 
 342         return gnt_list_entry;
 343 }
 344 
 345 static inline void grant_foreign_access(const struct grant *gnt_list_entry,
 346                                         const struct blkfront_info *info)
 347 {
 348         gnttab_page_grant_foreign_access_ref_one(gnt_list_entry->gref,
 349                                                  info->xbdev->otherend_id,
 350                                                  gnt_list_entry->page,
 351                                                  0);
 352 }
 353 
 354 static struct grant *get_grant(grant_ref_t *gref_head,
 355                                unsigned long gfn,
 356                                struct blkfront_ring_info *rinfo)
 357 {
 358         struct grant *gnt_list_entry = get_free_grant(rinfo);
 359         struct blkfront_info *info = rinfo->dev_info;
 360 
 361         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 362                 return gnt_list_entry;
 363 
 364         /* Assign a gref to this page */
 365         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 366         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 367         if (info->feature_persistent)
 368                 grant_foreign_access(gnt_list_entry, info);
 369         else {
 370                 /* Grant access to the GFN passed by the caller */
 371                 gnttab_grant_foreign_access_ref(gnt_list_entry->gref,
 372                                                 info->xbdev->otherend_id,
 373                                                 gfn, 0);
 374         }
 375 
 376         return gnt_list_entry;
 377 }
 378 
 379 static struct grant *get_indirect_grant(grant_ref_t *gref_head,
 380                                         struct blkfront_ring_info *rinfo)
 381 {
 382         struct grant *gnt_list_entry = get_free_grant(rinfo);
 383         struct blkfront_info *info = rinfo->dev_info;
 384 
 385         if (gnt_list_entry->gref != GRANT_INVALID_REF)
 386                 return gnt_list_entry;
 387 
 388         /* Assign a gref to this page */
 389         gnt_list_entry->gref = gnttab_claim_grant_reference(gref_head);
 390         BUG_ON(gnt_list_entry->gref == -ENOSPC);
 391         if (!info->feature_persistent) {
 392                 struct page *indirect_page;
 393 
 394                 /* Fetch a pre-allocated page to use for indirect grefs */
 395                 BUG_ON(list_empty(&rinfo->indirect_pages));
 396                 indirect_page = list_first_entry(&rinfo->indirect_pages,
 397                                                  struct page, lru);
 398                 list_del(&indirect_page->lru);
 399                 gnt_list_entry->page = indirect_page;
 400         }
 401         grant_foreign_access(gnt_list_entry, info);
 402 
 403         return gnt_list_entry;
 404 }
 405 
 406 static const char *op_name(int op)
 407 {
 408         static const char *const names[] = {
 409                 [BLKIF_OP_READ] = "read",
 410                 [BLKIF_OP_WRITE] = "write",
 411                 [BLKIF_OP_WRITE_BARRIER] = "barrier",
 412                 [BLKIF_OP_FLUSH_DISKCACHE] = "flush",
 413                 [BLKIF_OP_DISCARD] = "discard" };
 414 
 415         if (op < 0 || op >= ARRAY_SIZE(names))
 416                 return "unknown";
 417 
 418         if (!names[op])
 419                 return "reserved";
 420 
 421         return names[op];
 422 }
 423 static int xlbd_reserve_minors(unsigned int minor, unsigned int nr)
 424 {
 425         unsigned int end = minor + nr;
 426         int rc;
 427 
 428         if (end > nr_minors) {
 429                 unsigned long *bitmap, *old;
 430 
 431                 bitmap = kcalloc(BITS_TO_LONGS(end), sizeof(*bitmap),
 432                                  GFP_KERNEL);
 433                 if (bitmap == NULL)
 434                         return -ENOMEM;
 435 
 436                 spin_lock(&minor_lock);
 437                 if (end > nr_minors) {
 438                         old = minors;
 439                         memcpy(bitmap, minors,
 440                                BITS_TO_LONGS(nr_minors) * sizeof(*bitmap));
 441                         minors = bitmap;
 442                         nr_minors = BITS_TO_LONGS(end) * BITS_PER_LONG;
 443                 } else
 444                         old = bitmap;
 445                 spin_unlock(&minor_lock);
 446                 kfree(old);
 447         }
 448 
 449         spin_lock(&minor_lock);
 450         if (find_next_bit(minors, end, minor) >= end) {
 451                 bitmap_set(minors, minor, nr);
 452                 rc = 0;
 453         } else
 454                 rc = -EBUSY;
 455         spin_unlock(&minor_lock);
 456 
 457         return rc;
 458 }
 459 
 460 static void xlbd_release_minors(unsigned int minor, unsigned int nr)
 461 {
 462         unsigned int end = minor + nr;
 463 
 464         BUG_ON(end > nr_minors);
 465         spin_lock(&minor_lock);
 466         bitmap_clear(minors,  minor, nr);
 467         spin_unlock(&minor_lock);
 468 }
 469 
 470 static void blkif_restart_queue_callback(void *arg)
 471 {
 472         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)arg;
 473         schedule_work(&rinfo->work);
 474 }
 475 
 476 static int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
 477 {
 478         /* We don't have real geometry info, but let's at least return
 479            values consistent with the size of the device */
 480         sector_t nsect = get_capacity(bd->bd_disk);
 481         sector_t cylinders = nsect;
 482 
 483         hg->heads = 0xff;
 484         hg->sectors = 0x3f;
 485         sector_div(cylinders, hg->heads * hg->sectors);
 486         hg->cylinders = cylinders;
 487         if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
 488                 hg->cylinders = 0xffff;
 489         return 0;
 490 }
 491 
 492 static int blkif_ioctl(struct block_device *bdev, fmode_t mode,
 493                        unsigned command, unsigned long argument)
 494 {
 495         struct blkfront_info *info = bdev->bd_disk->private_data;
 496         int i;
 497 
 498         dev_dbg(&info->xbdev->dev, "command: 0x%x, argument: 0x%lx\n",
 499                 command, (long)argument);
 500 
 501         switch (command) {
 502         case CDROMMULTISESSION:
 503                 dev_dbg(&info->xbdev->dev, "FIXME: support multisession CDs later\n");
 504                 for (i = 0; i < sizeof(struct cdrom_multisession); i++)
 505                         if (put_user(0, (char __user *)(argument + i)))
 506                                 return -EFAULT;
 507                 return 0;
 508 
 509         case CDROM_GET_CAPABILITY: {
 510                 struct gendisk *gd = info->gd;
 511                 if (gd->flags & GENHD_FL_CD)
 512                         return 0;
 513                 return -EINVAL;
 514         }
 515 
 516         default:
 517                 /*printk(KERN_ALERT "ioctl %08x not supported by Xen blkdev\n",
 518                   command);*/
 519                 return -EINVAL; /* same return as native Linux */
 520         }
 521 
 522         return 0;
 523 }
 524 
 525 static unsigned long blkif_ring_get_request(struct blkfront_ring_info *rinfo,
 526                                             struct request *req,
 527                                             struct blkif_request **ring_req)
 528 {
 529         unsigned long id;
 530 
 531         *ring_req = RING_GET_REQUEST(&rinfo->ring, rinfo->ring.req_prod_pvt);
 532         rinfo->ring.req_prod_pvt++;
 533 
 534         id = get_id_from_freelist(rinfo);
 535         rinfo->shadow[id].request = req;
 536         rinfo->shadow[id].status = REQ_WAITING;
 537         rinfo->shadow[id].associated_id = NO_ASSOCIATED_ID;
 538 
 539         (*ring_req)->u.rw.id = id;
 540 
 541         return id;
 542 }
 543 
 544 static int blkif_queue_discard_req(struct request *req, struct blkfront_ring_info *rinfo)
 545 {
 546         struct blkfront_info *info = rinfo->dev_info;
 547         struct blkif_request *ring_req;
 548         unsigned long id;
 549 
 550         /* Fill out a communications ring structure. */
 551         id = blkif_ring_get_request(rinfo, req, &ring_req);
 552 
 553         ring_req->operation = BLKIF_OP_DISCARD;
 554         ring_req->u.discard.nr_sectors = blk_rq_sectors(req);
 555         ring_req->u.discard.id = id;
 556         ring_req->u.discard.sector_number = (blkif_sector_t)blk_rq_pos(req);
 557         if (req_op(req) == REQ_OP_SECURE_ERASE && info->feature_secdiscard)
 558                 ring_req->u.discard.flag = BLKIF_DISCARD_SECURE;
 559         else
 560                 ring_req->u.discard.flag = 0;
 561 
 562         /* Keep a private copy so we can reissue requests when recovering. */
 563         rinfo->shadow[id].req = *ring_req;
 564 
 565         return 0;
 566 }
 567 
 568 struct setup_rw_req {
 569         unsigned int grant_idx;
 570         struct blkif_request_segment *segments;
 571         struct blkfront_ring_info *rinfo;
 572         struct blkif_request *ring_req;
 573         grant_ref_t gref_head;
 574         unsigned int id;
 575         /* Only used when persistent grant is used and it's a read request */
 576         bool need_copy;
 577         unsigned int bvec_off;
 578         char *bvec_data;
 579 
 580         bool require_extra_req;
 581         struct blkif_request *extra_ring_req;
 582 };
 583 
 584 static void blkif_setup_rw_req_grant(unsigned long gfn, unsigned int offset,
 585                                      unsigned int len, void *data)
 586 {
 587         struct setup_rw_req *setup = data;
 588         int n, ref;
 589         struct grant *gnt_list_entry;
 590         unsigned int fsect, lsect;
 591         /* Convenient aliases */
 592         unsigned int grant_idx = setup->grant_idx;
 593         struct blkif_request *ring_req = setup->ring_req;
 594         struct blkfront_ring_info *rinfo = setup->rinfo;
 595         /*
 596          * We always use the shadow of the first request to store the list
 597          * of grant associated to the block I/O request. This made the
 598          * completion more easy to handle even if the block I/O request is
 599          * split.
 600          */
 601         struct blk_shadow *shadow = &rinfo->shadow[setup->id];
 602 
 603         if (unlikely(setup->require_extra_req &&
 604                      grant_idx >= BLKIF_MAX_SEGMENTS_PER_REQUEST)) {
 605                 /*
 606                  * We are using the second request, setup grant_idx
 607                  * to be the index of the segment array.
 608                  */
 609                 grant_idx -= BLKIF_MAX_SEGMENTS_PER_REQUEST;
 610                 ring_req = setup->extra_ring_req;
 611         }
 612 
 613         if ((ring_req->operation == BLKIF_OP_INDIRECT) &&
 614             (grant_idx % GRANTS_PER_INDIRECT_FRAME == 0)) {
 615                 if (setup->segments)
 616                         kunmap_atomic(setup->segments);
 617 
 618                 n = grant_idx / GRANTS_PER_INDIRECT_FRAME;
 619                 gnt_list_entry = get_indirect_grant(&setup->gref_head, rinfo);
 620                 shadow->indirect_grants[n] = gnt_list_entry;
 621                 setup->segments = kmap_atomic(gnt_list_entry->page);
 622                 ring_req->u.indirect.indirect_grefs[n] = gnt_list_entry->gref;
 623         }
 624 
 625         gnt_list_entry = get_grant(&setup->gref_head, gfn, rinfo);
 626         ref = gnt_list_entry->gref;
 627         /*
 628          * All the grants are stored in the shadow of the first
 629          * request. Therefore we have to use the global index.
 630          */
 631         shadow->grants_used[setup->grant_idx] = gnt_list_entry;
 632 
 633         if (setup->need_copy) {
 634                 void *shared_data;
 635 
 636                 shared_data = kmap_atomic(gnt_list_entry->page);
 637                 /*
 638                  * this does not wipe data stored outside the
 639                  * range sg->offset..sg->offset+sg->length.
 640                  * Therefore, blkback *could* see data from
 641                  * previous requests. This is OK as long as
 642                  * persistent grants are shared with just one
 643                  * domain. It may need refactoring if this
 644                  * changes
 645                  */
 646                 memcpy(shared_data + offset,
 647                        setup->bvec_data + setup->bvec_off,
 648                        len);
 649 
 650                 kunmap_atomic(shared_data);
 651                 setup->bvec_off += len;
 652         }
 653 
 654         fsect = offset >> 9;
 655         lsect = fsect + (len >> 9) - 1;
 656         if (ring_req->operation != BLKIF_OP_INDIRECT) {
 657                 ring_req->u.rw.seg[grant_idx] =
 658                         (struct blkif_request_segment) {
 659                                 .gref       = ref,
 660                                 .first_sect = fsect,
 661                                 .last_sect  = lsect };
 662         } else {
 663                 setup->segments[grant_idx % GRANTS_PER_INDIRECT_FRAME] =
 664                         (struct blkif_request_segment) {
 665                                 .gref       = ref,
 666                                 .first_sect = fsect,
 667                                 .last_sect  = lsect };
 668         }
 669 
 670         (setup->grant_idx)++;
 671 }
 672 
 673 static void blkif_setup_extra_req(struct blkif_request *first,
 674                                   struct blkif_request *second)
 675 {
 676         uint16_t nr_segments = first->u.rw.nr_segments;
 677 
 678         /*
 679          * The second request is only present when the first request uses
 680          * all its segments. It's always the continuity of the first one.
 681          */
 682         first->u.rw.nr_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
 683 
 684         second->u.rw.nr_segments = nr_segments - BLKIF_MAX_SEGMENTS_PER_REQUEST;
 685         second->u.rw.sector_number = first->u.rw.sector_number +
 686                 (BLKIF_MAX_SEGMENTS_PER_REQUEST * XEN_PAGE_SIZE) / 512;
 687 
 688         second->u.rw.handle = first->u.rw.handle;
 689         second->operation = first->operation;
 690 }
 691 
 692 static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *rinfo)
 693 {
 694         struct blkfront_info *info = rinfo->dev_info;
 695         struct blkif_request *ring_req, *extra_ring_req = NULL;
 696         unsigned long id, extra_id = NO_ASSOCIATED_ID;
 697         bool require_extra_req = false;
 698         int i;
 699         struct setup_rw_req setup = {
 700                 .grant_idx = 0,
 701                 .segments = NULL,
 702                 .rinfo = rinfo,
 703                 .need_copy = rq_data_dir(req) && info->feature_persistent,
 704         };
 705 
 706         /*
 707          * Used to store if we are able to queue the request by just using
 708          * existing persistent grants, or if we have to get new grants,
 709          * as there are not sufficiently many free.
 710          */
 711         bool new_persistent_gnts = false;
 712         struct scatterlist *sg;
 713         int num_sg, max_grefs, num_grant;
 714 
 715         max_grefs = req->nr_phys_segments * GRANTS_PER_PSEG;
 716         if (max_grefs > BLKIF_MAX_SEGMENTS_PER_REQUEST)
 717                 /*
 718                  * If we are using indirect segments we need to account
 719                  * for the indirect grefs used in the request.
 720                  */
 721                 max_grefs += INDIRECT_GREFS(max_grefs);
 722 
 723         /* Check if we have enough persistent grants to allocate a requests */
 724         if (rinfo->persistent_gnts_c < max_grefs) {
 725                 new_persistent_gnts = true;
 726 
 727                 if (gnttab_alloc_grant_references(
 728                     max_grefs - rinfo->persistent_gnts_c,
 729                     &setup.gref_head) < 0) {
 730                         gnttab_request_free_callback(
 731                                 &rinfo->callback,
 732                                 blkif_restart_queue_callback,
 733                                 rinfo,
 734                                 max_grefs - rinfo->persistent_gnts_c);
 735                         return 1;
 736                 }
 737         }
 738 
 739         /* Fill out a communications ring structure. */
 740         id = blkif_ring_get_request(rinfo, req, &ring_req);
 741 
 742         num_sg = blk_rq_map_sg(req->q, req, rinfo->shadow[id].sg);
 743         num_grant = 0;
 744         /* Calculate the number of grant used */
 745         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i)
 746                num_grant += gnttab_count_grant(sg->offset, sg->length);
 747 
 748         require_extra_req = info->max_indirect_segments == 0 &&
 749                 num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST;
 750         BUG_ON(!HAS_EXTRA_REQ && require_extra_req);
 751 
 752         rinfo->shadow[id].num_sg = num_sg;
 753         if (num_grant > BLKIF_MAX_SEGMENTS_PER_REQUEST &&
 754             likely(!require_extra_req)) {
 755                 /*
 756                  * The indirect operation can only be a BLKIF_OP_READ or
 757                  * BLKIF_OP_WRITE
 758                  */
 759                 BUG_ON(req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA);
 760                 ring_req->operation = BLKIF_OP_INDIRECT;
 761                 ring_req->u.indirect.indirect_op = rq_data_dir(req) ?
 762                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 763                 ring_req->u.indirect.sector_number = (blkif_sector_t)blk_rq_pos(req);
 764                 ring_req->u.indirect.handle = info->handle;
 765                 ring_req->u.indirect.nr_segments = num_grant;
 766         } else {
 767                 ring_req->u.rw.sector_number = (blkif_sector_t)blk_rq_pos(req);
 768                 ring_req->u.rw.handle = info->handle;
 769                 ring_req->operation = rq_data_dir(req) ?
 770                         BLKIF_OP_WRITE : BLKIF_OP_READ;
 771                 if (req_op(req) == REQ_OP_FLUSH || req->cmd_flags & REQ_FUA) {
 772                         /*
 773                          * Ideally we can do an unordered flush-to-disk.
 774                          * In case the backend onlysupports barriers, use that.
 775                          * A barrier request a superset of FUA, so we can
 776                          * implement it the same way.  (It's also a FLUSH+FUA,
 777                          * since it is guaranteed ordered WRT previous writes.)
 778                          */
 779                         if (info->feature_flush && info->feature_fua)
 780                                 ring_req->operation =
 781                                         BLKIF_OP_WRITE_BARRIER;
 782                         else if (info->feature_flush)
 783                                 ring_req->operation =
 784                                         BLKIF_OP_FLUSH_DISKCACHE;
 785                         else
 786                                 ring_req->operation = 0;
 787                 }
 788                 ring_req->u.rw.nr_segments = num_grant;
 789                 if (unlikely(require_extra_req)) {
 790                         extra_id = blkif_ring_get_request(rinfo, req,
 791                                                           &extra_ring_req);
 792                         /*
 793                          * Only the first request contains the scatter-gather
 794                          * list.
 795                          */
 796                         rinfo->shadow[extra_id].num_sg = 0;
 797 
 798                         blkif_setup_extra_req(ring_req, extra_ring_req);
 799 
 800                         /* Link the 2 requests together */
 801                         rinfo->shadow[extra_id].associated_id = id;
 802                         rinfo->shadow[id].associated_id = extra_id;
 803                 }
 804         }
 805 
 806         setup.ring_req = ring_req;
 807         setup.id = id;
 808 
 809         setup.require_extra_req = require_extra_req;
 810         if (unlikely(require_extra_req))
 811                 setup.extra_ring_req = extra_ring_req;
 812 
 813         for_each_sg(rinfo->shadow[id].sg, sg, num_sg, i) {
 814                 BUG_ON(sg->offset + sg->length > PAGE_SIZE);
 815 
 816                 if (setup.need_copy) {
 817                         setup.bvec_off = sg->offset;
 818                         setup.bvec_data = kmap_atomic(sg_page(sg));
 819                 }
 820 
 821                 gnttab_foreach_grant_in_range(sg_page(sg),
 822                                               sg->offset,
 823                                               sg->length,
 824                                               blkif_setup_rw_req_grant,
 825                                               &setup);
 826 
 827                 if (setup.need_copy)
 828                         kunmap_atomic(setup.bvec_data);
 829         }
 830         if (setup.segments)
 831                 kunmap_atomic(setup.segments);
 832 
 833         /* Keep a private copy so we can reissue requests when recovering. */
 834         rinfo->shadow[id].req = *ring_req;
 835         if (unlikely(require_extra_req))
 836                 rinfo->shadow[extra_id].req = *extra_ring_req;
 837 
 838         if (new_persistent_gnts)
 839                 gnttab_free_grant_references(setup.gref_head);
 840 
 841         return 0;
 842 }
 843 
 844 /*
 845  * Generate a Xen blkfront IO request from a blk layer request.  Reads
 846  * and writes are handled as expected.
 847  *
 848  * @req: a request struct
 849  */
 850 static int blkif_queue_request(struct request *req, struct blkfront_ring_info *rinfo)
 851 {
 852         if (unlikely(rinfo->dev_info->connected != BLKIF_STATE_CONNECTED))
 853                 return 1;
 854 
 855         if (unlikely(req_op(req) == REQ_OP_DISCARD ||
 856                      req_op(req) == REQ_OP_SECURE_ERASE))
 857                 return blkif_queue_discard_req(req, rinfo);
 858         else
 859                 return blkif_queue_rw_req(req, rinfo);
 860 }
 861 
 862 static inline void flush_requests(struct blkfront_ring_info *rinfo)
 863 {
 864         int notify;
 865 
 866         RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&rinfo->ring, notify);
 867 
 868         if (notify)
 869                 notify_remote_via_irq(rinfo->irq);
 870 }
 871 
 872 static inline bool blkif_request_flush_invalid(struct request *req,
 873                                                struct blkfront_info *info)
 874 {
 875         return (blk_rq_is_passthrough(req) ||
 876                 ((req_op(req) == REQ_OP_FLUSH) &&
 877                  !info->feature_flush) ||
 878                 ((req->cmd_flags & REQ_FUA) &&
 879                  !info->feature_fua));
 880 }
 881 
 882 static blk_status_t blkif_queue_rq(struct blk_mq_hw_ctx *hctx,
 883                           const struct blk_mq_queue_data *qd)
 884 {
 885         unsigned long flags;
 886         int qid = hctx->queue_num;
 887         struct blkfront_info *info = hctx->queue->queuedata;
 888         struct blkfront_ring_info *rinfo = NULL;
 889 
 890         BUG_ON(info->nr_rings <= qid);
 891         rinfo = &info->rinfo[qid];
 892         blk_mq_start_request(qd->rq);
 893         spin_lock_irqsave(&rinfo->ring_lock, flags);
 894         if (RING_FULL(&rinfo->ring))
 895                 goto out_busy;
 896 
 897         if (blkif_request_flush_invalid(qd->rq, rinfo->dev_info))
 898                 goto out_err;
 899 
 900         if (blkif_queue_request(qd->rq, rinfo))
 901                 goto out_busy;
 902 
 903         flush_requests(rinfo);
 904         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 905         return BLK_STS_OK;
 906 
 907 out_err:
 908         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 909         return BLK_STS_IOERR;
 910 
 911 out_busy:
 912         blk_mq_stop_hw_queue(hctx);
 913         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
 914         return BLK_STS_DEV_RESOURCE;
 915 }
 916 
 917 static void blkif_complete_rq(struct request *rq)
 918 {
 919         blk_mq_end_request(rq, blkif_req(rq)->error);
 920 }
 921 
 922 static const struct blk_mq_ops blkfront_mq_ops = {
 923         .queue_rq = blkif_queue_rq,
 924         .complete = blkif_complete_rq,
 925 };
 926 
 927 static void blkif_set_queue_limits(struct blkfront_info *info)
 928 {
 929         struct request_queue *rq = info->rq;
 930         struct gendisk *gd = info->gd;
 931         unsigned int segments = info->max_indirect_segments ? :
 932                                 BLKIF_MAX_SEGMENTS_PER_REQUEST;
 933 
 934         blk_queue_flag_set(QUEUE_FLAG_VIRT, rq);
 935 
 936         if (info->feature_discard) {
 937                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, rq);
 938                 blk_queue_max_discard_sectors(rq, get_capacity(gd));
 939                 rq->limits.discard_granularity = info->discard_granularity;
 940                 rq->limits.discard_alignment = info->discard_alignment;
 941                 if (info->feature_secdiscard)
 942                         blk_queue_flag_set(QUEUE_FLAG_SECERASE, rq);
 943         }
 944 
 945         /* Hard sector size and max sectors impersonate the equiv. hardware. */
 946         blk_queue_logical_block_size(rq, info->sector_size);
 947         blk_queue_physical_block_size(rq, info->physical_sector_size);
 948         blk_queue_max_hw_sectors(rq, (segments * XEN_PAGE_SIZE) / 512);
 949 
 950         /* Each segment in a request is up to an aligned page in size. */
 951         blk_queue_segment_boundary(rq, PAGE_SIZE - 1);
 952         blk_queue_max_segment_size(rq, PAGE_SIZE);
 953 
 954         /* Ensure a merged request will fit in a single I/O ring slot. */
 955         blk_queue_max_segments(rq, segments / GRANTS_PER_PSEG);
 956 
 957         /* Make sure buffer addresses are sector-aligned. */
 958         blk_queue_dma_alignment(rq, 511);
 959 }
 960 
 961 static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
 962                                 unsigned int physical_sector_size)
 963 {
 964         struct request_queue *rq;
 965         struct blkfront_info *info = gd->private_data;
 966 
 967         memset(&info->tag_set, 0, sizeof(info->tag_set));
 968         info->tag_set.ops = &blkfront_mq_ops;
 969         info->tag_set.nr_hw_queues = info->nr_rings;
 970         if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
 971                 /*
 972                  * When indirect descriptior is not supported, the I/O request
 973                  * will be split between multiple request in the ring.
 974                  * To avoid problems when sending the request, divide by
 975                  * 2 the depth of the queue.
 976                  */
 977                 info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
 978         } else
 979                 info->tag_set.queue_depth = BLK_RING_SIZE(info);
 980         info->tag_set.numa_node = NUMA_NO_NODE;
 981         info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
 982         info->tag_set.cmd_size = sizeof(struct blkif_req);
 983         info->tag_set.driver_data = info;
 984 
 985         if (blk_mq_alloc_tag_set(&info->tag_set))
 986                 return -EINVAL;
 987         rq = blk_mq_init_queue(&info->tag_set);
 988         if (IS_ERR(rq)) {
 989                 blk_mq_free_tag_set(&info->tag_set);
 990                 return PTR_ERR(rq);
 991         }
 992 
 993         rq->queuedata = info;
 994         info->rq = gd->queue = rq;
 995         info->gd = gd;
 996         info->sector_size = sector_size;
 997         info->physical_sector_size = physical_sector_size;
 998         blkif_set_queue_limits(info);
 999 
1000         return 0;
1001 }
1002 
1003 static const char *flush_info(struct blkfront_info *info)
1004 {
1005         if (info->feature_flush && info->feature_fua)
1006                 return "barrier: enabled;";
1007         else if (info->feature_flush)
1008                 return "flush diskcache: enabled;";
1009         else
1010                 return "barrier or flush: disabled;";
1011 }
1012 
1013 static void xlvbd_flush(struct blkfront_info *info)
1014 {
1015         blk_queue_write_cache(info->rq, info->feature_flush ? true : false,
1016                               info->feature_fua ? true : false);
1017         pr_info("blkfront: %s: %s %s %s %s %s\n",
1018                 info->gd->disk_name, flush_info(info),
1019                 "persistent grants:", info->feature_persistent ?
1020                 "enabled;" : "disabled;", "indirect descriptors:",
1021                 info->max_indirect_segments ? "enabled;" : "disabled;");
1022 }
1023 
1024 static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)
1025 {
1026         int major;
1027         major = BLKIF_MAJOR(vdevice);
1028         *minor = BLKIF_MINOR(vdevice);
1029         switch (major) {
1030                 case XEN_IDE0_MAJOR:
1031                         *offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;
1032                         *minor = ((*minor / 64) * PARTS_PER_DISK) +
1033                                 EMULATED_HD_DISK_MINOR_OFFSET;
1034                         break;
1035                 case XEN_IDE1_MAJOR:
1036                         *offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;
1037                         *minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +
1038                                 EMULATED_HD_DISK_MINOR_OFFSET;
1039                         break;
1040                 case XEN_SCSI_DISK0_MAJOR:
1041                         *offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;
1042                         *minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;
1043                         break;
1044                 case XEN_SCSI_DISK1_MAJOR:
1045                 case XEN_SCSI_DISK2_MAJOR:
1046                 case XEN_SCSI_DISK3_MAJOR:
1047                 case XEN_SCSI_DISK4_MAJOR:
1048                 case XEN_SCSI_DISK5_MAJOR:
1049                 case XEN_SCSI_DISK6_MAJOR:
1050                 case XEN_SCSI_DISK7_MAJOR:
1051                         *offset = (*minor / PARTS_PER_DISK) + 
1052                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +
1053                                 EMULATED_SD_DISK_NAME_OFFSET;
1054                         *minor = *minor +
1055                                 ((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +
1056                                 EMULATED_SD_DISK_MINOR_OFFSET;
1057                         break;
1058                 case XEN_SCSI_DISK8_MAJOR:
1059                 case XEN_SCSI_DISK9_MAJOR:
1060                 case XEN_SCSI_DISK10_MAJOR:
1061                 case XEN_SCSI_DISK11_MAJOR:
1062                 case XEN_SCSI_DISK12_MAJOR:
1063                 case XEN_SCSI_DISK13_MAJOR:
1064                 case XEN_SCSI_DISK14_MAJOR:
1065                 case XEN_SCSI_DISK15_MAJOR:
1066                         *offset = (*minor / PARTS_PER_DISK) + 
1067                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +
1068                                 EMULATED_SD_DISK_NAME_OFFSET;
1069                         *minor = *minor +
1070                                 ((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +
1071                                 EMULATED_SD_DISK_MINOR_OFFSET;
1072                         break;
1073                 case XENVBD_MAJOR:
1074                         *offset = *minor / PARTS_PER_DISK;
1075                         break;
1076                 default:
1077                         printk(KERN_WARNING "blkfront: your disk configuration is "
1078                                         "incorrect, please use an xvd device instead\n");
1079                         return -ENODEV;
1080         }
1081         return 0;
1082 }
1083 
1084 static char *encode_disk_name(char *ptr, unsigned int n)
1085 {
1086         if (n >= 26)
1087                 ptr = encode_disk_name(ptr, n / 26 - 1);
1088         *ptr = 'a' + n % 26;
1089         return ptr + 1;
1090 }
1091 
1092 static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
1093                                struct blkfront_info *info,
1094                                u16 vdisk_info, u16 sector_size,
1095                                unsigned int physical_sector_size)
1096 {
1097         struct gendisk *gd;
1098         int nr_minors = 1;
1099         int err;
1100         unsigned int offset;
1101         int minor;
1102         int nr_parts;
1103         char *ptr;
1104 
1105         BUG_ON(info->gd != NULL);
1106         BUG_ON(info->rq != NULL);
1107 
1108         if ((info->vdevice>>EXT_SHIFT) > 1) {
1109                 /* this is above the extended range; something is wrong */
1110                 printk(KERN_WARNING "blkfront: vdevice 0x%x is above the extended range; ignoring\n", info->vdevice);
1111                 return -ENODEV;
1112         }
1113 
1114         if (!VDEV_IS_EXTENDED(info->vdevice)) {
1115                 err = xen_translate_vdev(info->vdevice, &minor, &offset);
1116                 if (err)
1117                         return err;
1118                 nr_parts = PARTS_PER_DISK;
1119         } else {
1120                 minor = BLKIF_MINOR_EXT(info->vdevice);
1121                 nr_parts = PARTS_PER_EXT_DISK;
1122                 offset = minor / nr_parts;
1123                 if (xen_hvm_domain() && offset < EMULATED_HD_DISK_NAME_OFFSET + 4)
1124                         printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "
1125                                         "emulated IDE disks,\n\t choose an xvd device name"
1126                                         "from xvde on\n", info->vdevice);
1127         }
1128         if (minor >> MINORBITS) {
1129                 pr_warn("blkfront: %#x's minor (%#x) out of range; ignoring\n",
1130                         info->vdevice, minor);
1131                 return -ENODEV;
1132         }
1133 
1134         if ((minor % nr_parts) == 0)
1135                 nr_minors = nr_parts;
1136 
1137         err = xlbd_reserve_minors(minor, nr_minors);
1138         if (err)
1139                 goto out;
1140         err = -ENODEV;
1141 
1142         gd = alloc_disk(nr_minors);
1143         if (gd == NULL)
1144                 goto release;
1145 
1146         strcpy(gd->disk_name, DEV_NAME);
1147         ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
1148         BUG_ON(ptr >= gd->disk_name + DISK_NAME_LEN);
1149         if (nr_minors > 1)
1150                 *ptr = 0;
1151         else
1152                 snprintf(ptr, gd->disk_name + DISK_NAME_LEN - ptr,
1153                          "%d", minor & (nr_parts - 1));
1154 
1155         gd->major = XENVBD_MAJOR;
1156         gd->first_minor = minor;
1157         gd->fops = &xlvbd_block_fops;
1158         gd->private_data = info;
1159         set_capacity(gd, capacity);
1160 
1161         if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
1162                 del_gendisk(gd);
1163                 goto release;
1164         }
1165 
1166         xlvbd_flush(info);
1167 
1168         if (vdisk_info & VDISK_READONLY)
1169                 set_disk_ro(gd, 1);
1170 
1171         if (vdisk_info & VDISK_REMOVABLE)
1172                 gd->flags |= GENHD_FL_REMOVABLE;
1173 
1174         if (vdisk_info & VDISK_CDROM)
1175                 gd->flags |= GENHD_FL_CD;
1176 
1177         return 0;
1178 
1179  release:
1180         xlbd_release_minors(minor, nr_minors);
1181  out:
1182         return err;
1183 }
1184 
1185 static void xlvbd_release_gendisk(struct blkfront_info *info)
1186 {
1187         unsigned int minor, nr_minors, i;
1188 
1189         if (info->rq == NULL)
1190                 return;
1191 
1192         /* No more blkif_request(). */
1193         blk_mq_stop_hw_queues(info->rq);
1194 
1195         for (i = 0; i < info->nr_rings; i++) {
1196                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1197 
1198                 /* No more gnttab callback work. */
1199                 gnttab_cancel_free_callback(&rinfo->callback);
1200 
1201                 /* Flush gnttab callback work. Must be done with no locks held. */
1202                 flush_work(&rinfo->work);
1203         }
1204 
1205         del_gendisk(info->gd);
1206 
1207         minor = info->gd->first_minor;
1208         nr_minors = info->gd->minors;
1209         xlbd_release_minors(minor, nr_minors);
1210 
1211         blk_cleanup_queue(info->rq);
1212         blk_mq_free_tag_set(&info->tag_set);
1213         info->rq = NULL;
1214 
1215         put_disk(info->gd);
1216         info->gd = NULL;
1217 }
1218 
1219 /* Already hold rinfo->ring_lock. */
1220 static inline void kick_pending_request_queues_locked(struct blkfront_ring_info *rinfo)
1221 {
1222         if (!RING_FULL(&rinfo->ring))
1223                 blk_mq_start_stopped_hw_queues(rinfo->dev_info->rq, true);
1224 }
1225 
1226 static void kick_pending_request_queues(struct blkfront_ring_info *rinfo)
1227 {
1228         unsigned long flags;
1229 
1230         spin_lock_irqsave(&rinfo->ring_lock, flags);
1231         kick_pending_request_queues_locked(rinfo);
1232         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1233 }
1234 
1235 static void blkif_restart_queue(struct work_struct *work)
1236 {
1237         struct blkfront_ring_info *rinfo = container_of(work, struct blkfront_ring_info, work);
1238 
1239         if (rinfo->dev_info->connected == BLKIF_STATE_CONNECTED)
1240                 kick_pending_request_queues(rinfo);
1241 }
1242 
1243 static void blkif_free_ring(struct blkfront_ring_info *rinfo)
1244 {
1245         struct grant *persistent_gnt, *n;
1246         struct blkfront_info *info = rinfo->dev_info;
1247         int i, j, segs;
1248 
1249         /*
1250          * Remove indirect pages, this only happens when using indirect
1251          * descriptors but not persistent grants
1252          */
1253         if (!list_empty(&rinfo->indirect_pages)) {
1254                 struct page *indirect_page, *n;
1255 
1256                 BUG_ON(info->feature_persistent);
1257                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
1258                         list_del(&indirect_page->lru);
1259                         __free_page(indirect_page);
1260                 }
1261         }
1262 
1263         /* Remove all persistent grants. */
1264         if (!list_empty(&rinfo->grants)) {
1265                 list_for_each_entry_safe(persistent_gnt, n,
1266                                          &rinfo->grants, node) {
1267                         list_del(&persistent_gnt->node);
1268                         if (persistent_gnt->gref != GRANT_INVALID_REF) {
1269                                 gnttab_end_foreign_access(persistent_gnt->gref,
1270                                                           0, 0UL);
1271                                 rinfo->persistent_gnts_c--;
1272                         }
1273                         if (info->feature_persistent)
1274                                 __free_page(persistent_gnt->page);
1275                         kfree(persistent_gnt);
1276                 }
1277         }
1278         BUG_ON(rinfo->persistent_gnts_c != 0);
1279 
1280         for (i = 0; i < BLK_RING_SIZE(info); i++) {
1281                 /*
1282                  * Clear persistent grants present in requests already
1283                  * on the shared ring
1284                  */
1285                 if (!rinfo->shadow[i].request)
1286                         goto free_shadow;
1287 
1288                 segs = rinfo->shadow[i].req.operation == BLKIF_OP_INDIRECT ?
1289                        rinfo->shadow[i].req.u.indirect.nr_segments :
1290                        rinfo->shadow[i].req.u.rw.nr_segments;
1291                 for (j = 0; j < segs; j++) {
1292                         persistent_gnt = rinfo->shadow[i].grants_used[j];
1293                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1294                         if (info->feature_persistent)
1295                                 __free_page(persistent_gnt->page);
1296                         kfree(persistent_gnt);
1297                 }
1298 
1299                 if (rinfo->shadow[i].req.operation != BLKIF_OP_INDIRECT)
1300                         /*
1301                          * If this is not an indirect operation don't try to
1302                          * free indirect segments
1303                          */
1304                         goto free_shadow;
1305 
1306                 for (j = 0; j < INDIRECT_GREFS(segs); j++) {
1307                         persistent_gnt = rinfo->shadow[i].indirect_grants[j];
1308                         gnttab_end_foreign_access(persistent_gnt->gref, 0, 0UL);
1309                         __free_page(persistent_gnt->page);
1310                         kfree(persistent_gnt);
1311                 }
1312 
1313 free_shadow:
1314                 kvfree(rinfo->shadow[i].grants_used);
1315                 rinfo->shadow[i].grants_used = NULL;
1316                 kvfree(rinfo->shadow[i].indirect_grants);
1317                 rinfo->shadow[i].indirect_grants = NULL;
1318                 kvfree(rinfo->shadow[i].sg);
1319                 rinfo->shadow[i].sg = NULL;
1320         }
1321 
1322         /* No more gnttab callback work. */
1323         gnttab_cancel_free_callback(&rinfo->callback);
1324 
1325         /* Flush gnttab callback work. Must be done with no locks held. */
1326         flush_work(&rinfo->work);
1327 
1328         /* Free resources associated with old device channel. */
1329         for (i = 0; i < info->nr_ring_pages; i++) {
1330                 if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
1331                         gnttab_end_foreign_access(rinfo->ring_ref[i], 0, 0);
1332                         rinfo->ring_ref[i] = GRANT_INVALID_REF;
1333                 }
1334         }
1335         free_pages((unsigned long)rinfo->ring.sring, get_order(info->nr_ring_pages * XEN_PAGE_SIZE));
1336         rinfo->ring.sring = NULL;
1337 
1338         if (rinfo->irq)
1339                 unbind_from_irqhandler(rinfo->irq, rinfo);
1340         rinfo->evtchn = rinfo->irq = 0;
1341 }
1342 
1343 static void blkif_free(struct blkfront_info *info, int suspend)
1344 {
1345         unsigned int i;
1346 
1347         /* Prevent new requests being issued until we fix things up. */
1348         info->connected = suspend ?
1349                 BLKIF_STATE_SUSPENDED : BLKIF_STATE_DISCONNECTED;
1350         /* No more blkif_request(). */
1351         if (info->rq)
1352                 blk_mq_stop_hw_queues(info->rq);
1353 
1354         for (i = 0; i < info->nr_rings; i++)
1355                 blkif_free_ring(&info->rinfo[i]);
1356 
1357         kvfree(info->rinfo);
1358         info->rinfo = NULL;
1359         info->nr_rings = 0;
1360 }
1361 
1362 struct copy_from_grant {
1363         const struct blk_shadow *s;
1364         unsigned int grant_idx;
1365         unsigned int bvec_offset;
1366         char *bvec_data;
1367 };
1368 
1369 static void blkif_copy_from_grant(unsigned long gfn, unsigned int offset,
1370                                   unsigned int len, void *data)
1371 {
1372         struct copy_from_grant *info = data;
1373         char *shared_data;
1374         /* Convenient aliases */
1375         const struct blk_shadow *s = info->s;
1376 
1377         shared_data = kmap_atomic(s->grants_used[info->grant_idx]->page);
1378 
1379         memcpy(info->bvec_data + info->bvec_offset,
1380                shared_data + offset, len);
1381 
1382         info->bvec_offset += len;
1383         info->grant_idx++;
1384 
1385         kunmap_atomic(shared_data);
1386 }
1387 
1388 static enum blk_req_status blkif_rsp_to_req_status(int rsp)
1389 {
1390         switch (rsp)
1391         {
1392         case BLKIF_RSP_OKAY:
1393                 return REQ_DONE;
1394         case BLKIF_RSP_EOPNOTSUPP:
1395                 return REQ_EOPNOTSUPP;
1396         case BLKIF_RSP_ERROR:
1397                 /* Fallthrough. */
1398         default:
1399                 return REQ_ERROR;
1400         }
1401 }
1402 
1403 /*
1404  * Get the final status of the block request based on two ring response
1405  */
1406 static int blkif_get_final_status(enum blk_req_status s1,
1407                                   enum blk_req_status s2)
1408 {
1409         BUG_ON(s1 == REQ_WAITING);
1410         BUG_ON(s2 == REQ_WAITING);
1411 
1412         if (s1 == REQ_ERROR || s2 == REQ_ERROR)
1413                 return BLKIF_RSP_ERROR;
1414         else if (s1 == REQ_EOPNOTSUPP || s2 == REQ_EOPNOTSUPP)
1415                 return BLKIF_RSP_EOPNOTSUPP;
1416         return BLKIF_RSP_OKAY;
1417 }
1418 
1419 static bool blkif_completion(unsigned long *id,
1420                              struct blkfront_ring_info *rinfo,
1421                              struct blkif_response *bret)
1422 {
1423         int i = 0;
1424         struct scatterlist *sg;
1425         int num_sg, num_grant;
1426         struct blkfront_info *info = rinfo->dev_info;
1427         struct blk_shadow *s = &rinfo->shadow[*id];
1428         struct copy_from_grant data = {
1429                 .grant_idx = 0,
1430         };
1431 
1432         num_grant = s->req.operation == BLKIF_OP_INDIRECT ?
1433                 s->req.u.indirect.nr_segments : s->req.u.rw.nr_segments;
1434 
1435         /* The I/O request may be split in two. */
1436         if (unlikely(s->associated_id != NO_ASSOCIATED_ID)) {
1437                 struct blk_shadow *s2 = &rinfo->shadow[s->associated_id];
1438 
1439                 /* Keep the status of the current response in shadow. */
1440                 s->status = blkif_rsp_to_req_status(bret->status);
1441 
1442                 /* Wait the second response if not yet here. */
1443                 if (s2->status == REQ_WAITING)
1444                         return false;
1445 
1446                 bret->status = blkif_get_final_status(s->status,
1447                                                       s2->status);
1448 
1449                 /*
1450                  * All the grants is stored in the first shadow in order
1451                  * to make the completion code simpler.
1452                  */
1453                 num_grant += s2->req.u.rw.nr_segments;
1454 
1455                 /*
1456                  * The two responses may not come in order. Only the
1457                  * first request will store the scatter-gather list.
1458                  */
1459                 if (s2->num_sg != 0) {
1460                         /* Update "id" with the ID of the first response. */
1461                         *id = s->associated_id;
1462                         s = s2;
1463                 }
1464 
1465                 /*
1466                  * We don't need anymore the second request, so recycling
1467                  * it now.
1468                  */
1469                 if (add_id_to_freelist(rinfo, s->associated_id))
1470                         WARN(1, "%s: can't recycle the second part (id = %ld) of the request\n",
1471                              info->gd->disk_name, s->associated_id);
1472         }
1473 
1474         data.s = s;
1475         num_sg = s->num_sg;
1476 
1477         if (bret->operation == BLKIF_OP_READ && info->feature_persistent) {
1478                 for_each_sg(s->sg, sg, num_sg, i) {
1479                         BUG_ON(sg->offset + sg->length > PAGE_SIZE);
1480 
1481                         data.bvec_offset = sg->offset;
1482                         data.bvec_data = kmap_atomic(sg_page(sg));
1483 
1484                         gnttab_foreach_grant_in_range(sg_page(sg),
1485                                                       sg->offset,
1486                                                       sg->length,
1487                                                       blkif_copy_from_grant,
1488                                                       &data);
1489 
1490                         kunmap_atomic(data.bvec_data);
1491                 }
1492         }
1493         /* Add the persistent grant into the list of free grants */
1494         for (i = 0; i < num_grant; i++) {
1495                 if (gnttab_query_foreign_access(s->grants_used[i]->gref)) {
1496                         /*
1497                          * If the grant is still mapped by the backend (the
1498                          * backend has chosen to make this grant persistent)
1499                          * we add it at the head of the list, so it will be
1500                          * reused first.
1501                          */
1502                         if (!info->feature_persistent)
1503                                 pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1504                                                      s->grants_used[i]->gref);
1505                         list_add(&s->grants_used[i]->node, &rinfo->grants);
1506                         rinfo->persistent_gnts_c++;
1507                 } else {
1508                         /*
1509                          * If the grant is not mapped by the backend we end the
1510                          * foreign access and add it to the tail of the list,
1511                          * so it will not be picked again unless we run out of
1512                          * persistent grants.
1513                          */
1514                         gnttab_end_foreign_access(s->grants_used[i]->gref, 0, 0UL);
1515                         s->grants_used[i]->gref = GRANT_INVALID_REF;
1516                         list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
1517                 }
1518         }
1519         if (s->req.operation == BLKIF_OP_INDIRECT) {
1520                 for (i = 0; i < INDIRECT_GREFS(num_grant); i++) {
1521                         if (gnttab_query_foreign_access(s->indirect_grants[i]->gref)) {
1522                                 if (!info->feature_persistent)
1523                                         pr_alert_ratelimited("backed has not unmapped grant: %u\n",
1524                                                              s->indirect_grants[i]->gref);
1525                                 list_add(&s->indirect_grants[i]->node, &rinfo->grants);
1526                                 rinfo->persistent_gnts_c++;
1527                         } else {
1528                                 struct page *indirect_page;
1529 
1530                                 gnttab_end_foreign_access(s->indirect_grants[i]->gref, 0, 0UL);
1531                                 /*
1532                                  * Add the used indirect page back to the list of
1533                                  * available pages for indirect grefs.
1534                                  */
1535                                 if (!info->feature_persistent) {
1536                                         indirect_page = s->indirect_grants[i]->page;
1537                                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
1538                                 }
1539                                 s->indirect_grants[i]->gref = GRANT_INVALID_REF;
1540                                 list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
1541                         }
1542                 }
1543         }
1544 
1545         return true;
1546 }
1547 
1548 static irqreturn_t blkif_interrupt(int irq, void *dev_id)
1549 {
1550         struct request *req;
1551         struct blkif_response *bret;
1552         RING_IDX i, rp;
1553         unsigned long flags;
1554         struct blkfront_ring_info *rinfo = (struct blkfront_ring_info *)dev_id;
1555         struct blkfront_info *info = rinfo->dev_info;
1556 
1557         if (unlikely(info->connected != BLKIF_STATE_CONNECTED))
1558                 return IRQ_HANDLED;
1559 
1560         spin_lock_irqsave(&rinfo->ring_lock, flags);
1561  again:
1562         rp = rinfo->ring.sring->rsp_prod;
1563         rmb(); /* Ensure we see queued responses up to 'rp'. */
1564 
1565         for (i = rinfo->ring.rsp_cons; i != rp; i++) {
1566                 unsigned long id;
1567 
1568                 bret = RING_GET_RESPONSE(&rinfo->ring, i);
1569                 id   = bret->id;
1570                 /*
1571                  * The backend has messed up and given us an id that we would
1572                  * never have given to it (we stamp it up to BLK_RING_SIZE -
1573                  * look in get_id_from_freelist.
1574                  */
1575                 if (id >= BLK_RING_SIZE(info)) {
1576                         WARN(1, "%s: response to %s has incorrect id (%ld)\n",
1577                              info->gd->disk_name, op_name(bret->operation), id);
1578                         /* We can't safely get the 'struct request' as
1579                          * the id is busted. */
1580                         continue;
1581                 }
1582                 req  = rinfo->shadow[id].request;
1583 
1584                 if (bret->operation != BLKIF_OP_DISCARD) {
1585                         /*
1586                          * We may need to wait for an extra response if the
1587                          * I/O request is split in 2
1588                          */
1589                         if (!blkif_completion(&id, rinfo, bret))
1590                                 continue;
1591                 }
1592 
1593                 if (add_id_to_freelist(rinfo, id)) {
1594                         WARN(1, "%s: response to %s (id %ld) couldn't be recycled!\n",
1595                              info->gd->disk_name, op_name(bret->operation), id);
1596                         continue;
1597                 }
1598 
1599                 if (bret->status == BLKIF_RSP_OKAY)
1600                         blkif_req(req)->error = BLK_STS_OK;
1601                 else
1602                         blkif_req(req)->error = BLK_STS_IOERR;
1603 
1604                 switch (bret->operation) {
1605                 case BLKIF_OP_DISCARD:
1606                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1607                                 struct request_queue *rq = info->rq;
1608                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1609                                            info->gd->disk_name, op_name(bret->operation));
1610                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1611                                 info->feature_discard = 0;
1612                                 info->feature_secdiscard = 0;
1613                                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, rq);
1614                                 blk_queue_flag_clear(QUEUE_FLAG_SECERASE, rq);
1615                         }
1616                         break;
1617                 case BLKIF_OP_FLUSH_DISKCACHE:
1618                 case BLKIF_OP_WRITE_BARRIER:
1619                         if (unlikely(bret->status == BLKIF_RSP_EOPNOTSUPP)) {
1620                                 printk(KERN_WARNING "blkfront: %s: %s op failed\n",
1621                                        info->gd->disk_name, op_name(bret->operation));
1622                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1623                         }
1624                         if (unlikely(bret->status == BLKIF_RSP_ERROR &&
1625                                      rinfo->shadow[id].req.u.rw.nr_segments == 0)) {
1626                                 printk(KERN_WARNING "blkfront: %s: empty %s op failed\n",
1627                                        info->gd->disk_name, op_name(bret->operation));
1628                                 blkif_req(req)->error = BLK_STS_NOTSUPP;
1629                         }
1630                         if (unlikely(blkif_req(req)->error)) {
1631                                 if (blkif_req(req)->error == BLK_STS_NOTSUPP)
1632                                         blkif_req(req)->error = BLK_STS_OK;
1633                                 info->feature_fua = 0;
1634                                 info->feature_flush = 0;
1635                                 xlvbd_flush(info);
1636                         }
1637                         /* fall through */
1638                 case BLKIF_OP_READ:
1639                 case BLKIF_OP_WRITE:
1640                         if (unlikely(bret->status != BLKIF_RSP_OKAY))
1641                                 dev_dbg(&info->xbdev->dev, "Bad return from blkdev data "
1642                                         "request: %x\n", bret->status);
1643 
1644                         break;
1645                 default:
1646                         BUG();
1647                 }
1648 
1649                 blk_mq_complete_request(req);
1650         }
1651 
1652         rinfo->ring.rsp_cons = i;
1653 
1654         if (i != rinfo->ring.req_prod_pvt) {
1655                 int more_to_do;
1656                 RING_FINAL_CHECK_FOR_RESPONSES(&rinfo->ring, more_to_do);
1657                 if (more_to_do)
1658                         goto again;
1659         } else
1660                 rinfo->ring.sring->rsp_event = i + 1;
1661 
1662         kick_pending_request_queues_locked(rinfo);
1663 
1664         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
1665 
1666         return IRQ_HANDLED;
1667 }
1668 
1669 
1670 static int setup_blkring(struct xenbus_device *dev,
1671                          struct blkfront_ring_info *rinfo)
1672 {
1673         struct blkif_sring *sring;
1674         int err, i;
1675         struct blkfront_info *info = rinfo->dev_info;
1676         unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
1677         grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
1678 
1679         for (i = 0; i < info->nr_ring_pages; i++)
1680                 rinfo->ring_ref[i] = GRANT_INVALID_REF;
1681 
1682         sring = (struct blkif_sring *)__get_free_pages(GFP_NOIO | __GFP_HIGH,
1683                                                        get_order(ring_size));
1684         if (!sring) {
1685                 xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
1686                 return -ENOMEM;
1687         }
1688         SHARED_RING_INIT(sring);
1689         FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
1690 
1691         err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
1692         if (err < 0) {
1693                 free_pages((unsigned long)sring, get_order(ring_size));
1694                 rinfo->ring.sring = NULL;
1695                 goto fail;
1696         }
1697         for (i = 0; i < info->nr_ring_pages; i++)
1698                 rinfo->ring_ref[i] = gref[i];
1699 
1700         err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
1701         if (err)
1702                 goto fail;
1703 
1704         err = bind_evtchn_to_irqhandler(rinfo->evtchn, blkif_interrupt, 0,
1705                                         "blkif", rinfo);
1706         if (err <= 0) {
1707                 xenbus_dev_fatal(dev, err,
1708                                  "bind_evtchn_to_irqhandler failed");
1709                 goto fail;
1710         }
1711         rinfo->irq = err;
1712 
1713         return 0;
1714 fail:
1715         blkif_free(info, 0);
1716         return err;
1717 }
1718 
1719 /*
1720  * Write out per-ring/queue nodes including ring-ref and event-channel, and each
1721  * ring buffer may have multi pages depending on ->nr_ring_pages.
1722  */
1723 static int write_per_ring_nodes(struct xenbus_transaction xbt,
1724                                 struct blkfront_ring_info *rinfo, const char *dir)
1725 {
1726         int err;
1727         unsigned int i;
1728         const char *message = NULL;
1729         struct blkfront_info *info = rinfo->dev_info;
1730 
1731         if (info->nr_ring_pages == 1) {
1732                 err = xenbus_printf(xbt, dir, "ring-ref", "%u", rinfo->ring_ref[0]);
1733                 if (err) {
1734                         message = "writing ring-ref";
1735                         goto abort_transaction;
1736                 }
1737         } else {
1738                 for (i = 0; i < info->nr_ring_pages; i++) {
1739                         char ring_ref_name[RINGREF_NAME_LEN];
1740 
1741                         snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1742                         err = xenbus_printf(xbt, dir, ring_ref_name,
1743                                             "%u", rinfo->ring_ref[i]);
1744                         if (err) {
1745                                 message = "writing ring-ref";
1746                                 goto abort_transaction;
1747                         }
1748                 }
1749         }
1750 
1751         err = xenbus_printf(xbt, dir, "event-channel", "%u", rinfo->evtchn);
1752         if (err) {
1753                 message = "writing event-channel";
1754                 goto abort_transaction;
1755         }
1756 
1757         return 0;
1758 
1759 abort_transaction:
1760         xenbus_transaction_end(xbt, 1);
1761         if (message)
1762                 xenbus_dev_fatal(info->xbdev, err, "%s", message);
1763 
1764         return err;
1765 }
1766 
1767 static void free_info(struct blkfront_info *info)
1768 {
1769         list_del(&info->info_list);
1770         kfree(info);
1771 }
1772 
1773 /* Common code used when first setting up, and when resuming. */
1774 static int talk_to_blkback(struct xenbus_device *dev,
1775                            struct blkfront_info *info)
1776 {
1777         const char *message = NULL;
1778         struct xenbus_transaction xbt;
1779         int err;
1780         unsigned int i, max_page_order;
1781         unsigned int ring_page_order;
1782 
1783         if (!info)
1784                 return -ENODEV;
1785 
1786         max_page_order = xenbus_read_unsigned(info->xbdev->otherend,
1787                                               "max-ring-page-order", 0);
1788         ring_page_order = min(xen_blkif_max_ring_order, max_page_order);
1789         info->nr_ring_pages = 1 << ring_page_order;
1790 
1791         err = negotiate_mq(info);
1792         if (err)
1793                 goto destroy_blkring;
1794 
1795         for (i = 0; i < info->nr_rings; i++) {
1796                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1797 
1798                 /* Create shared ring, alloc event channel. */
1799                 err = setup_blkring(dev, rinfo);
1800                 if (err)
1801                         goto destroy_blkring;
1802         }
1803 
1804 again:
1805         err = xenbus_transaction_start(&xbt);
1806         if (err) {
1807                 xenbus_dev_fatal(dev, err, "starting transaction");
1808                 goto destroy_blkring;
1809         }
1810 
1811         if (info->nr_ring_pages > 1) {
1812                 err = xenbus_printf(xbt, dev->nodename, "ring-page-order", "%u",
1813                                     ring_page_order);
1814                 if (err) {
1815                         message = "writing ring-page-order";
1816                         goto abort_transaction;
1817                 }
1818         }
1819 
1820         /* We already got the number of queues/rings in _probe */
1821         if (info->nr_rings == 1) {
1822                 err = write_per_ring_nodes(xbt, &info->rinfo[0], dev->nodename);
1823                 if (err)
1824                         goto destroy_blkring;
1825         } else {
1826                 char *path;
1827                 size_t pathsize;
1828 
1829                 err = xenbus_printf(xbt, dev->nodename, "multi-queue-num-queues", "%u",
1830                                     info->nr_rings);
1831                 if (err) {
1832                         message = "writing multi-queue-num-queues";
1833                         goto abort_transaction;
1834                 }
1835 
1836                 pathsize = strlen(dev->nodename) + QUEUE_NAME_LEN;
1837                 path = kmalloc(pathsize, GFP_KERNEL);
1838                 if (!path) {
1839                         err = -ENOMEM;
1840                         message = "ENOMEM while writing ring references";
1841                         goto abort_transaction;
1842                 }
1843 
1844                 for (i = 0; i < info->nr_rings; i++) {
1845                         memset(path, 0, pathsize);
1846                         snprintf(path, pathsize, "%s/queue-%u", dev->nodename, i);
1847                         err = write_per_ring_nodes(xbt, &info->rinfo[i], path);
1848                         if (err) {
1849                                 kfree(path);
1850                                 goto destroy_blkring;
1851                         }
1852                 }
1853                 kfree(path);
1854         }
1855         err = xenbus_printf(xbt, dev->nodename, "protocol", "%s",
1856                             XEN_IO_PROTO_ABI_NATIVE);
1857         if (err) {
1858                 message = "writing protocol";
1859                 goto abort_transaction;
1860         }
1861         err = xenbus_printf(xbt, dev->nodename,
1862                             "feature-persistent", "%u", 1);
1863         if (err)
1864                 dev_warn(&dev->dev,
1865                          "writing persistent grants feature to xenbus");
1866 
1867         err = xenbus_transaction_end(xbt, 0);
1868         if (err) {
1869                 if (err == -EAGAIN)
1870                         goto again;
1871                 xenbus_dev_fatal(dev, err, "completing transaction");
1872                 goto destroy_blkring;
1873         }
1874 
1875         for (i = 0; i < info->nr_rings; i++) {
1876                 unsigned int j;
1877                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
1878 
1879                 for (j = 0; j < BLK_RING_SIZE(info); j++)
1880                         rinfo->shadow[j].req.u.rw.id = j + 1;
1881                 rinfo->shadow[BLK_RING_SIZE(info)-1].req.u.rw.id = 0x0fffffff;
1882         }
1883         xenbus_switch_state(dev, XenbusStateInitialised);
1884 
1885         return 0;
1886 
1887  abort_transaction:
1888         xenbus_transaction_end(xbt, 1);
1889         if (message)
1890                 xenbus_dev_fatal(dev, err, "%s", message);
1891  destroy_blkring:
1892         blkif_free(info, 0);
1893 
1894         mutex_lock(&blkfront_mutex);
1895         free_info(info);
1896         mutex_unlock(&blkfront_mutex);
1897 
1898         dev_set_drvdata(&dev->dev, NULL);
1899 
1900         return err;
1901 }
1902 
1903 static int negotiate_mq(struct blkfront_info *info)
1904 {
1905         unsigned int backend_max_queues;
1906         unsigned int i;
1907 
1908         BUG_ON(info->nr_rings);
1909 
1910         /* Check if backend supports multiple queues. */
1911         backend_max_queues = xenbus_read_unsigned(info->xbdev->otherend,
1912                                                   "multi-queue-max-queues", 1);
1913         info->nr_rings = min(backend_max_queues, xen_blkif_max_queues);
1914         /* We need at least one ring. */
1915         if (!info->nr_rings)
1916                 info->nr_rings = 1;
1917 
1918         info->rinfo = kvcalloc(info->nr_rings,
1919                                sizeof(struct blkfront_ring_info),
1920                                GFP_KERNEL);
1921         if (!info->rinfo) {
1922                 xenbus_dev_fatal(info->xbdev, -ENOMEM, "allocating ring_info structure");
1923                 info->nr_rings = 0;
1924                 return -ENOMEM;
1925         }
1926 
1927         for (i = 0; i < info->nr_rings; i++) {
1928                 struct blkfront_ring_info *rinfo;
1929 
1930                 rinfo = &info->rinfo[i];
1931                 INIT_LIST_HEAD(&rinfo->indirect_pages);
1932                 INIT_LIST_HEAD(&rinfo->grants);
1933                 rinfo->dev_info = info;
1934                 INIT_WORK(&rinfo->work, blkif_restart_queue);
1935                 spin_lock_init(&rinfo->ring_lock);
1936         }
1937         return 0;
1938 }
1939 /**
1940  * Entry point to this code when a new device is created.  Allocate the basic
1941  * structures and the ring buffer for communication with the backend, and
1942  * inform the backend of the appropriate details for those.  Switch to
1943  * Initialised state.
1944  */
1945 static int blkfront_probe(struct xenbus_device *dev,
1946                           const struct xenbus_device_id *id)
1947 {
1948         int err, vdevice;
1949         struct blkfront_info *info;
1950 
1951         /* FIXME: Use dynamic device id if this is not set. */
1952         err = xenbus_scanf(XBT_NIL, dev->nodename,
1953                            "virtual-device", "%i", &vdevice);
1954         if (err != 1) {
1955                 /* go looking in the extended area instead */
1956                 err = xenbus_scanf(XBT_NIL, dev->nodename, "virtual-device-ext",
1957                                    "%i", &vdevice);
1958                 if (err != 1) {
1959                         xenbus_dev_fatal(dev, err, "reading virtual-device");
1960                         return err;
1961                 }
1962         }
1963 
1964         if (xen_hvm_domain()) {
1965                 char *type;
1966                 int len;
1967                 /* no unplug has been done: do not hook devices != xen vbds */
1968                 if (xen_has_pv_and_legacy_disk_devices()) {
1969                         int major;
1970 
1971                         if (!VDEV_IS_EXTENDED(vdevice))
1972                                 major = BLKIF_MAJOR(vdevice);
1973                         else
1974                                 major = XENVBD_MAJOR;
1975 
1976                         if (major != XENVBD_MAJOR) {
1977                                 printk(KERN_INFO
1978                                                 "%s: HVM does not support vbd %d as xen block device\n",
1979                                                 __func__, vdevice);
1980                                 return -ENODEV;
1981                         }
1982                 }
1983                 /* do not create a PV cdrom device if we are an HVM guest */
1984                 type = xenbus_read(XBT_NIL, dev->nodename, "device-type", &len);
1985                 if (IS_ERR(type))
1986                         return -ENODEV;
1987                 if (strncmp(type, "cdrom", 5) == 0) {
1988                         kfree(type);
1989                         return -ENODEV;
1990                 }
1991                 kfree(type);
1992         }
1993         info = kzalloc(sizeof(*info), GFP_KERNEL);
1994         if (!info) {
1995                 xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
1996                 return -ENOMEM;
1997         }
1998 
1999         info->xbdev = dev;
2000 
2001         mutex_init(&info->mutex);
2002         info->vdevice = vdevice;
2003         info->connected = BLKIF_STATE_DISCONNECTED;
2004 
2005         /* Front end dir is a number, which is used as the id. */
2006         info->handle = simple_strtoul(strrchr(dev->nodename, '/')+1, NULL, 0);
2007         dev_set_drvdata(&dev->dev, info);
2008 
2009         mutex_lock(&blkfront_mutex);
2010         list_add(&info->info_list, &info_list);
2011         mutex_unlock(&blkfront_mutex);
2012 
2013         return 0;
2014 }
2015 
2016 static int blkif_recover(struct blkfront_info *info)
2017 {
2018         unsigned int r_index;
2019         struct request *req, *n;
2020         int rc;
2021         struct bio *bio;
2022         unsigned int segs;
2023 
2024         blkfront_gather_backend_features(info);
2025         /* Reset limits changed by blk_mq_update_nr_hw_queues(). */
2026         blkif_set_queue_limits(info);
2027         segs = info->max_indirect_segments ? : BLKIF_MAX_SEGMENTS_PER_REQUEST;
2028         blk_queue_max_segments(info->rq, segs / GRANTS_PER_PSEG);
2029 
2030         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2031                 struct blkfront_ring_info *rinfo = &info->rinfo[r_index];
2032 
2033                 rc = blkfront_setup_indirect(rinfo);
2034                 if (rc)
2035                         return rc;
2036         }
2037         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2038 
2039         /* Now safe for us to use the shared ring */
2040         info->connected = BLKIF_STATE_CONNECTED;
2041 
2042         for (r_index = 0; r_index < info->nr_rings; r_index++) {
2043                 struct blkfront_ring_info *rinfo;
2044 
2045                 rinfo = &info->rinfo[r_index];
2046                 /* Kick any other new requests queued since we resumed */
2047                 kick_pending_request_queues(rinfo);
2048         }
2049 
2050         list_for_each_entry_safe(req, n, &info->requests, queuelist) {
2051                 /* Requeue pending requests (flush or discard) */
2052                 list_del_init(&req->queuelist);
2053                 BUG_ON(req->nr_phys_segments > segs);
2054                 blk_mq_requeue_request(req, false);
2055         }
2056         blk_mq_start_stopped_hw_queues(info->rq, true);
2057         blk_mq_kick_requeue_list(info->rq);
2058 
2059         while ((bio = bio_list_pop(&info->bio_list)) != NULL) {
2060                 /* Traverse the list of pending bios and re-queue them */
2061                 submit_bio(bio);
2062         }
2063 
2064         return 0;
2065 }
2066 
2067 /**
2068  * We are reconnecting to the backend, due to a suspend/resume, or a backend
2069  * driver restart.  We tear down our blkif structure and recreate it, but
2070  * leave the device-layer structures intact so that this is transparent to the
2071  * rest of the kernel.
2072  */
2073 static int blkfront_resume(struct xenbus_device *dev)
2074 {
2075         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2076         int err = 0;
2077         unsigned int i, j;
2078 
2079         dev_dbg(&dev->dev, "blkfront_resume: %s\n", dev->nodename);
2080 
2081         bio_list_init(&info->bio_list);
2082         INIT_LIST_HEAD(&info->requests);
2083         for (i = 0; i < info->nr_rings; i++) {
2084                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2085                 struct bio_list merge_bio;
2086                 struct blk_shadow *shadow = rinfo->shadow;
2087 
2088                 for (j = 0; j < BLK_RING_SIZE(info); j++) {
2089                         /* Not in use? */
2090                         if (!shadow[j].request)
2091                                 continue;
2092 
2093                         /*
2094                          * Get the bios in the request so we can re-queue them.
2095                          */
2096                         if (req_op(shadow[j].request) == REQ_OP_FLUSH ||
2097                             req_op(shadow[j].request) == REQ_OP_DISCARD ||
2098                             req_op(shadow[j].request) == REQ_OP_SECURE_ERASE ||
2099                             shadow[j].request->cmd_flags & REQ_FUA) {
2100                                 /*
2101                                  * Flush operations don't contain bios, so
2102                                  * we need to requeue the whole request
2103                                  *
2104                                  * XXX: but this doesn't make any sense for a
2105                                  * write with the FUA flag set..
2106                                  */
2107                                 list_add(&shadow[j].request->queuelist, &info->requests);
2108                                 continue;
2109                         }
2110                         merge_bio.head = shadow[j].request->bio;
2111                         merge_bio.tail = shadow[j].request->biotail;
2112                         bio_list_merge(&info->bio_list, &merge_bio);
2113                         shadow[j].request->bio = NULL;
2114                         blk_mq_end_request(shadow[j].request, BLK_STS_OK);
2115                 }
2116         }
2117 
2118         blkif_free(info, info->connected == BLKIF_STATE_CONNECTED);
2119 
2120         err = talk_to_blkback(dev, info);
2121         if (!err)
2122                 blk_mq_update_nr_hw_queues(&info->tag_set, info->nr_rings);
2123 
2124         /*
2125          * We have to wait for the backend to switch to
2126          * connected state, since we want to read which
2127          * features it supports.
2128          */
2129 
2130         return err;
2131 }
2132 
2133 static void blkfront_closing(struct blkfront_info *info)
2134 {
2135         struct xenbus_device *xbdev = info->xbdev;
2136         struct block_device *bdev = NULL;
2137 
2138         mutex_lock(&info->mutex);
2139 
2140         if (xbdev->state == XenbusStateClosing) {
2141                 mutex_unlock(&info->mutex);
2142                 return;
2143         }
2144 
2145         if (info->gd)
2146                 bdev = bdget_disk(info->gd, 0);
2147 
2148         mutex_unlock(&info->mutex);
2149 
2150         if (!bdev) {
2151                 xenbus_frontend_closed(xbdev);
2152                 return;
2153         }
2154 
2155         mutex_lock(&bdev->bd_mutex);
2156 
2157         if (bdev->bd_openers) {
2158                 xenbus_dev_error(xbdev, -EBUSY,
2159                                  "Device in use; refusing to close");
2160                 xenbus_switch_state(xbdev, XenbusStateClosing);
2161         } else {
2162                 xlvbd_release_gendisk(info);
2163                 xenbus_frontend_closed(xbdev);
2164         }
2165 
2166         mutex_unlock(&bdev->bd_mutex);
2167         bdput(bdev);
2168 }
2169 
2170 static void blkfront_setup_discard(struct blkfront_info *info)
2171 {
2172         int err;
2173         unsigned int discard_granularity;
2174         unsigned int discard_alignment;
2175 
2176         info->feature_discard = 1;
2177         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2178                 "discard-granularity", "%u", &discard_granularity,
2179                 "discard-alignment", "%u", &discard_alignment,
2180                 NULL);
2181         if (!err) {
2182                 info->discard_granularity = discard_granularity;
2183                 info->discard_alignment = discard_alignment;
2184         }
2185         info->feature_secdiscard =
2186                 !!xenbus_read_unsigned(info->xbdev->otherend, "discard-secure",
2187                                        0);
2188 }
2189 
2190 static int blkfront_setup_indirect(struct blkfront_ring_info *rinfo)
2191 {
2192         unsigned int psegs, grants, memflags;
2193         int err, i;
2194         struct blkfront_info *info = rinfo->dev_info;
2195 
2196         memflags = memalloc_noio_save();
2197 
2198         if (info->max_indirect_segments == 0) {
2199                 if (!HAS_EXTRA_REQ)
2200                         grants = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2201                 else {
2202                         /*
2203                          * When an extra req is required, the maximum
2204                          * grants supported is related to the size of the
2205                          * Linux block segment.
2206                          */
2207                         grants = GRANTS_PER_PSEG;
2208                 }
2209         }
2210         else
2211                 grants = info->max_indirect_segments;
2212         psegs = DIV_ROUND_UP(grants, GRANTS_PER_PSEG);
2213 
2214         err = fill_grant_buffer(rinfo,
2215                                 (grants + INDIRECT_GREFS(grants)) * BLK_RING_SIZE(info));
2216         if (err)
2217                 goto out_of_memory;
2218 
2219         if (!info->feature_persistent && info->max_indirect_segments) {
2220                 /*
2221                  * We are using indirect descriptors but not persistent
2222                  * grants, we need to allocate a set of pages that can be
2223                  * used for mapping indirect grefs
2224                  */
2225                 int num = INDIRECT_GREFS(grants) * BLK_RING_SIZE(info);
2226 
2227                 BUG_ON(!list_empty(&rinfo->indirect_pages));
2228                 for (i = 0; i < num; i++) {
2229                         struct page *indirect_page = alloc_page(GFP_KERNEL);
2230                         if (!indirect_page)
2231                                 goto out_of_memory;
2232                         list_add(&indirect_page->lru, &rinfo->indirect_pages);
2233                 }
2234         }
2235 
2236         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2237                 rinfo->shadow[i].grants_used =
2238                         kvcalloc(grants,
2239                                  sizeof(rinfo->shadow[i].grants_used[0]),
2240                                  GFP_KERNEL);
2241                 rinfo->shadow[i].sg = kvcalloc(psegs,
2242                                                sizeof(rinfo->shadow[i].sg[0]),
2243                                                GFP_KERNEL);
2244                 if (info->max_indirect_segments)
2245                         rinfo->shadow[i].indirect_grants =
2246                                 kvcalloc(INDIRECT_GREFS(grants),
2247                                          sizeof(rinfo->shadow[i].indirect_grants[0]),
2248                                          GFP_KERNEL);
2249                 if ((rinfo->shadow[i].grants_used == NULL) ||
2250                         (rinfo->shadow[i].sg == NULL) ||
2251                      (info->max_indirect_segments &&
2252                      (rinfo->shadow[i].indirect_grants == NULL)))
2253                         goto out_of_memory;
2254                 sg_init_table(rinfo->shadow[i].sg, psegs);
2255         }
2256 
2257         memalloc_noio_restore(memflags);
2258 
2259         return 0;
2260 
2261 out_of_memory:
2262         for (i = 0; i < BLK_RING_SIZE(info); i++) {
2263                 kvfree(rinfo->shadow[i].grants_used);
2264                 rinfo->shadow[i].grants_used = NULL;
2265                 kvfree(rinfo->shadow[i].sg);
2266                 rinfo->shadow[i].sg = NULL;
2267                 kvfree(rinfo->shadow[i].indirect_grants);
2268                 rinfo->shadow[i].indirect_grants = NULL;
2269         }
2270         if (!list_empty(&rinfo->indirect_pages)) {
2271                 struct page *indirect_page, *n;
2272                 list_for_each_entry_safe(indirect_page, n, &rinfo->indirect_pages, lru) {
2273                         list_del(&indirect_page->lru);
2274                         __free_page(indirect_page);
2275                 }
2276         }
2277 
2278         memalloc_noio_restore(memflags);
2279 
2280         return -ENOMEM;
2281 }
2282 
2283 /*
2284  * Gather all backend feature-*
2285  */
2286 static void blkfront_gather_backend_features(struct blkfront_info *info)
2287 {
2288         unsigned int indirect_segments;
2289 
2290         info->feature_flush = 0;
2291         info->feature_fua = 0;
2292 
2293         /*
2294          * If there's no "feature-barrier" defined, then it means
2295          * we're dealing with a very old backend which writes
2296          * synchronously; nothing to do.
2297          *
2298          * If there are barriers, then we use flush.
2299          */
2300         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-barrier", 0)) {
2301                 info->feature_flush = 1;
2302                 info->feature_fua = 1;
2303         }
2304 
2305         /*
2306          * And if there is "feature-flush-cache" use that above
2307          * barriers.
2308          */
2309         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-flush-cache",
2310                                  0)) {
2311                 info->feature_flush = 1;
2312                 info->feature_fua = 0;
2313         }
2314 
2315         if (xenbus_read_unsigned(info->xbdev->otherend, "feature-discard", 0))
2316                 blkfront_setup_discard(info);
2317 
2318         info->feature_persistent =
2319                 !!xenbus_read_unsigned(info->xbdev->otherend,
2320                                        "feature-persistent", 0);
2321 
2322         indirect_segments = xenbus_read_unsigned(info->xbdev->otherend,
2323                                         "feature-max-indirect-segments", 0);
2324         if (indirect_segments > xen_blkif_max_segments)
2325                 indirect_segments = xen_blkif_max_segments;
2326         if (indirect_segments <= BLKIF_MAX_SEGMENTS_PER_REQUEST)
2327                 indirect_segments = 0;
2328         info->max_indirect_segments = indirect_segments;
2329 
2330         if (info->feature_persistent) {
2331                 mutex_lock(&blkfront_mutex);
2332                 schedule_delayed_work(&blkfront_work, HZ * 10);
2333                 mutex_unlock(&blkfront_mutex);
2334         }
2335 }
2336 
2337 /*
2338  * Invoked when the backend is finally 'ready' (and has told produced
2339  * the details about the physical device - #sectors, size, etc).
2340  */
2341 static void blkfront_connect(struct blkfront_info *info)
2342 {
2343         unsigned long long sectors;
2344         unsigned long sector_size;
2345         unsigned int physical_sector_size;
2346         unsigned int binfo;
2347         char *envp[] = { "RESIZE=1", NULL };
2348         int err, i;
2349 
2350         switch (info->connected) {
2351         case BLKIF_STATE_CONNECTED:
2352                 /*
2353                  * Potentially, the back-end may be signalling
2354                  * a capacity change; update the capacity.
2355                  */
2356                 err = xenbus_scanf(XBT_NIL, info->xbdev->otherend,
2357                                    "sectors", "%Lu", &sectors);
2358                 if (XENBUS_EXIST_ERR(err))
2359                         return;
2360                 printk(KERN_INFO "Setting capacity to %Lu\n",
2361                        sectors);
2362                 set_capacity(info->gd, sectors);
2363                 revalidate_disk(info->gd);
2364                 kobject_uevent_env(&disk_to_dev(info->gd)->kobj,
2365                                    KOBJ_CHANGE, envp);
2366 
2367                 return;
2368         case BLKIF_STATE_SUSPENDED:
2369                 /*
2370                  * If we are recovering from suspension, we need to wait
2371                  * for the backend to announce it's features before
2372                  * reconnecting, at least we need to know if the backend
2373                  * supports indirect descriptors, and how many.
2374                  */
2375                 blkif_recover(info);
2376                 return;
2377 
2378         default:
2379                 break;
2380         }
2381 
2382         dev_dbg(&info->xbdev->dev, "%s:%s.\n",
2383                 __func__, info->xbdev->otherend);
2384 
2385         err = xenbus_gather(XBT_NIL, info->xbdev->otherend,
2386                             "sectors", "%llu", &sectors,
2387                             "info", "%u", &binfo,
2388                             "sector-size", "%lu", &sector_size,
2389                             NULL);
2390         if (err) {
2391                 xenbus_dev_fatal(info->xbdev, err,
2392                                  "reading backend fields at %s",
2393                                  info->xbdev->otherend);
2394                 return;
2395         }
2396 
2397         /*
2398          * physcial-sector-size is a newer field, so old backends may not
2399          * provide this. Assume physical sector size to be the same as
2400          * sector_size in that case.
2401          */
2402         physical_sector_size = xenbus_read_unsigned(info->xbdev->otherend,
2403                                                     "physical-sector-size",
2404                                                     sector_size);
2405         blkfront_gather_backend_features(info);
2406         for (i = 0; i < info->nr_rings; i++) {
2407                 err = blkfront_setup_indirect(&info->rinfo[i]);
2408                 if (err) {
2409                         xenbus_dev_fatal(info->xbdev, err, "setup_indirect at %s",
2410                                          info->xbdev->otherend);
2411                         blkif_free(info, 0);
2412                         break;
2413                 }
2414         }
2415 
2416         err = xlvbd_alloc_gendisk(sectors, info, binfo, sector_size,
2417                                   physical_sector_size);
2418         if (err) {
2419                 xenbus_dev_fatal(info->xbdev, err, "xlvbd_add at %s",
2420                                  info->xbdev->otherend);
2421                 goto fail;
2422         }
2423 
2424         xenbus_switch_state(info->xbdev, XenbusStateConnected);
2425 
2426         /* Kick pending requests. */
2427         info->connected = BLKIF_STATE_CONNECTED;
2428         for (i = 0; i < info->nr_rings; i++)
2429                 kick_pending_request_queues(&info->rinfo[i]);
2430 
2431         device_add_disk(&info->xbdev->dev, info->gd, NULL);
2432 
2433         info->is_ready = 1;
2434         return;
2435 
2436 fail:
2437         blkif_free(info, 0);
2438         return;
2439 }
2440 
2441 /**
2442  * Callback received when the backend's state changes.
2443  */
2444 static void blkback_changed(struct xenbus_device *dev,
2445                             enum xenbus_state backend_state)
2446 {
2447         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2448 
2449         dev_dbg(&dev->dev, "blkfront:blkback_changed to state %d.\n", backend_state);
2450 
2451         switch (backend_state) {
2452         case XenbusStateInitWait:
2453                 if (dev->state != XenbusStateInitialising)
2454                         break;
2455                 if (talk_to_blkback(dev, info))
2456                         break;
2457         case XenbusStateInitialising:
2458         case XenbusStateInitialised:
2459         case XenbusStateReconfiguring:
2460         case XenbusStateReconfigured:
2461         case XenbusStateUnknown:
2462                 break;
2463 
2464         case XenbusStateConnected:
2465                 /*
2466                  * talk_to_blkback sets state to XenbusStateInitialised
2467                  * and blkfront_connect sets it to XenbusStateConnected
2468                  * (if connection went OK).
2469                  *
2470                  * If the backend (or toolstack) decides to poke at backend
2471                  * state (and re-trigger the watch by setting the state repeatedly
2472                  * to XenbusStateConnected (4)) we need to deal with this.
2473                  * This is allowed as this is used to communicate to the guest
2474                  * that the size of disk has changed!
2475                  */
2476                 if ((dev->state != XenbusStateInitialised) &&
2477                     (dev->state != XenbusStateConnected)) {
2478                         if (talk_to_blkback(dev, info))
2479                                 break;
2480                 }
2481 
2482                 blkfront_connect(info);
2483                 break;
2484 
2485         case XenbusStateClosed:
2486                 if (dev->state == XenbusStateClosed)
2487                         break;
2488                 /* fall through */
2489         case XenbusStateClosing:
2490                 if (info)
2491                         blkfront_closing(info);
2492                 break;
2493         }
2494 }
2495 
2496 static int blkfront_remove(struct xenbus_device *xbdev)
2497 {
2498         struct blkfront_info *info = dev_get_drvdata(&xbdev->dev);
2499         struct block_device *bdev = NULL;
2500         struct gendisk *disk;
2501 
2502         dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
2503 
2504         if (!info)
2505                 return 0;
2506 
2507         blkif_free(info, 0);
2508 
2509         mutex_lock(&info->mutex);
2510 
2511         disk = info->gd;
2512         if (disk)
2513                 bdev = bdget_disk(disk, 0);
2514 
2515         info->xbdev = NULL;
2516         mutex_unlock(&info->mutex);
2517 
2518         if (!bdev) {
2519                 mutex_lock(&blkfront_mutex);
2520                 free_info(info);
2521                 mutex_unlock(&blkfront_mutex);
2522                 return 0;
2523         }
2524 
2525         /*
2526          * The xbdev was removed before we reached the Closed
2527          * state. See if it's safe to remove the disk. If the bdev
2528          * isn't closed yet, we let release take care of it.
2529          */
2530 
2531         mutex_lock(&bdev->bd_mutex);
2532         info = disk->private_data;
2533 
2534         dev_warn(disk_to_dev(disk),
2535                  "%s was hot-unplugged, %d stale handles\n",
2536                  xbdev->nodename, bdev->bd_openers);
2537 
2538         if (info && !bdev->bd_openers) {
2539                 xlvbd_release_gendisk(info);
2540                 disk->private_data = NULL;
2541                 mutex_lock(&blkfront_mutex);
2542                 free_info(info);
2543                 mutex_unlock(&blkfront_mutex);
2544         }
2545 
2546         mutex_unlock(&bdev->bd_mutex);
2547         bdput(bdev);
2548 
2549         return 0;
2550 }
2551 
2552 static int blkfront_is_ready(struct xenbus_device *dev)
2553 {
2554         struct blkfront_info *info = dev_get_drvdata(&dev->dev);
2555 
2556         return info->is_ready && info->xbdev;
2557 }
2558 
2559 static int blkif_open(struct block_device *bdev, fmode_t mode)
2560 {
2561         struct gendisk *disk = bdev->bd_disk;
2562         struct blkfront_info *info;
2563         int err = 0;
2564 
2565         mutex_lock(&blkfront_mutex);
2566 
2567         info = disk->private_data;
2568         if (!info) {
2569                 /* xbdev gone */
2570                 err = -ERESTARTSYS;
2571                 goto out;
2572         }
2573 
2574         mutex_lock(&info->mutex);
2575 
2576         if (!info->gd)
2577                 /* xbdev is closed */
2578                 err = -ERESTARTSYS;
2579 
2580         mutex_unlock(&info->mutex);
2581 
2582 out:
2583         mutex_unlock(&blkfront_mutex);
2584         return err;
2585 }
2586 
2587 static void blkif_release(struct gendisk *disk, fmode_t mode)
2588 {
2589         struct blkfront_info *info = disk->private_data;
2590         struct block_device *bdev;
2591         struct xenbus_device *xbdev;
2592 
2593         mutex_lock(&blkfront_mutex);
2594 
2595         bdev = bdget_disk(disk, 0);
2596 
2597         if (!bdev) {
2598                 WARN(1, "Block device %s yanked out from us!\n", disk->disk_name);
2599                 goto out_mutex;
2600         }
2601         if (bdev->bd_openers)
2602                 goto out;
2603 
2604         /*
2605          * Check if we have been instructed to close. We will have
2606          * deferred this request, because the bdev was still open.
2607          */
2608 
2609         mutex_lock(&info->mutex);
2610         xbdev = info->xbdev;
2611 
2612         if (xbdev && xbdev->state == XenbusStateClosing) {
2613                 /* pending switch to state closed */
2614                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2615                 xlvbd_release_gendisk(info);
2616                 xenbus_frontend_closed(info->xbdev);
2617         }
2618 
2619         mutex_unlock(&info->mutex);
2620 
2621         if (!xbdev) {
2622                 /* sudden device removal */
2623                 dev_info(disk_to_dev(bdev->bd_disk), "releasing disk\n");
2624                 xlvbd_release_gendisk(info);
2625                 disk->private_data = NULL;
2626                 free_info(info);
2627         }
2628 
2629 out:
2630         bdput(bdev);
2631 out_mutex:
2632         mutex_unlock(&blkfront_mutex);
2633 }
2634 
2635 static const struct block_device_operations xlvbd_block_fops =
2636 {
2637         .owner = THIS_MODULE,
2638         .open = blkif_open,
2639         .release = blkif_release,
2640         .getgeo = blkif_getgeo,
2641         .ioctl = blkif_ioctl,
2642 };
2643 
2644 
2645 static const struct xenbus_device_id blkfront_ids[] = {
2646         { "vbd" },
2647         { "" }
2648 };
2649 
2650 static struct xenbus_driver blkfront_driver = {
2651         .ids  = blkfront_ids,
2652         .probe = blkfront_probe,
2653         .remove = blkfront_remove,
2654         .resume = blkfront_resume,
2655         .otherend_changed = blkback_changed,
2656         .is_ready = blkfront_is_ready,
2657 };
2658 
2659 static void purge_persistent_grants(struct blkfront_info *info)
2660 {
2661         unsigned int i;
2662         unsigned long flags;
2663 
2664         for (i = 0; i < info->nr_rings; i++) {
2665                 struct blkfront_ring_info *rinfo = &info->rinfo[i];
2666                 struct grant *gnt_list_entry, *tmp;
2667 
2668                 spin_lock_irqsave(&rinfo->ring_lock, flags);
2669 
2670                 if (rinfo->persistent_gnts_c == 0) {
2671                         spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2672                         continue;
2673                 }
2674 
2675                 list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
2676                                          node) {
2677                         if (gnt_list_entry->gref == GRANT_INVALID_REF ||
2678                             gnttab_query_foreign_access(gnt_list_entry->gref))
2679                                 continue;
2680 
2681                         list_del(&gnt_list_entry->node);
2682                         gnttab_end_foreign_access(gnt_list_entry->gref, 0, 0UL);
2683                         rinfo->persistent_gnts_c--;
2684                         gnt_list_entry->gref = GRANT_INVALID_REF;
2685                         list_add_tail(&gnt_list_entry->node, &rinfo->grants);
2686                 }
2687 
2688                 spin_unlock_irqrestore(&rinfo->ring_lock, flags);
2689         }
2690 }
2691 
2692 static void blkfront_delay_work(struct work_struct *work)
2693 {
2694         struct blkfront_info *info;
2695         bool need_schedule_work = false;
2696 
2697         mutex_lock(&blkfront_mutex);
2698 
2699         list_for_each_entry(info, &info_list, info_list) {
2700                 if (info->feature_persistent) {
2701                         need_schedule_work = true;
2702                         mutex_lock(&info->mutex);
2703                         purge_persistent_grants(info);
2704                         mutex_unlock(&info->mutex);
2705                 }
2706         }
2707 
2708         if (need_schedule_work)
2709                 schedule_delayed_work(&blkfront_work, HZ * 10);
2710 
2711         mutex_unlock(&blkfront_mutex);
2712 }
2713 
2714 static int __init xlblk_init(void)
2715 {
2716         int ret;
2717         int nr_cpus = num_online_cpus();
2718 
2719         if (!xen_domain())
2720                 return -ENODEV;
2721 
2722         if (!xen_has_pv_disk_devices())
2723                 return -ENODEV;
2724 
2725         if (register_blkdev(XENVBD_MAJOR, DEV_NAME)) {
2726                 pr_warn("xen_blk: can't get major %d with name %s\n",
2727                         XENVBD_MAJOR, DEV_NAME);
2728                 return -ENODEV;
2729         }
2730 
2731         if (xen_blkif_max_segments < BLKIF_MAX_SEGMENTS_PER_REQUEST)
2732                 xen_blkif_max_segments = BLKIF_MAX_SEGMENTS_PER_REQUEST;
2733 
2734         if (xen_blkif_max_ring_order > XENBUS_MAX_RING_GRANT_ORDER) {
2735                 pr_info("Invalid max_ring_order (%d), will use default max: %d.\n",
2736                         xen_blkif_max_ring_order, XENBUS_MAX_RING_GRANT_ORDER);
2737                 xen_blkif_max_ring_order = XENBUS_MAX_RING_GRANT_ORDER;
2738         }
2739 
2740         if (xen_blkif_max_queues > nr_cpus) {
2741                 pr_info("Invalid max_queues (%d), will use default max: %d.\n",
2742                         xen_blkif_max_queues, nr_cpus);
2743                 xen_blkif_max_queues = nr_cpus;
2744         }
2745 
2746         INIT_DELAYED_WORK(&blkfront_work, blkfront_delay_work);
2747 
2748         ret = xenbus_register_frontend(&blkfront_driver);
2749         if (ret) {
2750                 unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2751                 return ret;
2752         }
2753 
2754         return 0;
2755 }
2756 module_init(xlblk_init);
2757 
2758 
2759 static void __exit xlblk_exit(void)
2760 {
2761         cancel_delayed_work_sync(&blkfront_work);
2762 
2763         xenbus_unregister_driver(&blkfront_driver);
2764         unregister_blkdev(XENVBD_MAJOR, DEV_NAME);
2765         kfree(minors);
2766 }
2767 module_exit(xlblk_exit);
2768 
2769 MODULE_DESCRIPTION("Xen virtual block device frontend");
2770 MODULE_LICENSE("GPL");
2771 MODULE_ALIAS_BLOCKDEV_MAJOR(XENVBD_MAJOR);
2772 MODULE_ALIAS("xen:vbd");
2773 MODULE_ALIAS("xenblk");
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/block/xen-blkfront.c

DEFINITIONS
