drivers/block/ublk_drv.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Userspace block device - block device which IO is handled from userspace
   4  *
   5  * Take full use of io_uring passthrough command for communicating with
   6  * ublk userspace daemon(ublksrvd) for handling basic IO request.
   7  *
   8  * Copyright 2022 Ming Lei <ming.lei@redhat.com>
   9  *
  10  * (part of code stolen from loop.c)
  11  */
  12 #include <linux/module.h>
  13 #include <linux/moduleparam.h>
  14 #include <linux/sched.h>
  15 #include <linux/fs.h>
  16 #include <linux/pagemap.h>
  17 #include <linux/file.h>
  18 #include <linux/stat.h>
  19 #include <linux/errno.h>
  20 #include <linux/major.h>
  21 #include <linux/wait.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/init.h>
  24 #include <linux/swap.h>
  25 #include <linux/slab.h>
  26 #include <linux/compat.h>
  27 #include <linux/mutex.h>
  28 #include <linux/writeback.h>
  29 #include <linux/completion.h>
  30 #include <linux/highmem.h>
  31 #include <linux/sysfs.h>
  32 #include <linux/miscdevice.h>
  33 #include <linux/falloc.h>
  34 #include <linux/uio.h>
  35 #include <linux/ioprio.h>
  36 #include <linux/sched/mm.h>
  37 #include <linux/uaccess.h>
  38 #include <linux/cdev.h>
  39 #include <linux/io_uring/cmd.h>
  40 #include <linux/blk-mq.h>
  41 #include <linux/delay.h>
  42 #include <linux/mm.h>
  43 #include <asm/page.h>
  44 #include <linux/task_work.h>
  45 #include <linux/namei.h>
  46 #include <linux/kref.h>
  47 #include <uapi/linux/ublk_cmd.h>
  48
  49 #define UBLK_MINORS             (1U << MINORBITS)
  50
  51 /* All UBLK_F_* have to be included into UBLK_F_ALL */
  52 #define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY \
  53                 | UBLK_F_URING_CMD_COMP_IN_TASK \
  54                 | UBLK_F_NEED_GET_DATA \
  55                 | UBLK_F_USER_RECOVERY \
  56                 | UBLK_F_USER_RECOVERY_REISSUE \
  57                 | UBLK_F_UNPRIVILEGED_DEV \
  58                 | UBLK_F_CMD_IOCTL_ENCODE \
  59                 | UBLK_F_USER_COPY \
  60                 | UBLK_F_ZONED)
  61
  62 /* All UBLK_PARAM_TYPE_* should be included here */
  63 #define UBLK_PARAM_TYPE_ALL                                \
  64         (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD | \
  65          UBLK_PARAM_TYPE_DEVT | UBLK_PARAM_TYPE_ZONED)
  66
  67 struct ublk_rq_data {
  68         struct llist_node node;
  69
  70         struct kref ref;
  71         __u64 sector;
  72         __u32 operation;
  73         __u32 nr_zones;
  74 };
  75
  76 struct ublk_uring_cmd_pdu {
  77         struct ublk_queue *ubq;
  78         u16 tag;
  79 };
  80
  81 /*
  82  * io command is active: sqe cmd is received, and its cqe isn't done
  83  *
  84  * If the flag is set, the io command is owned by ublk driver, and waited
  85  * for incoming blk-mq request from the ublk block device.
  86  *
  87  * If the flag is cleared, the io command will be completed, and owned by
  88  * ublk server.
  89  */
  90 #define UBLK_IO_FLAG_ACTIVE     0x01
  91
  92 /*
  93  * IO command is completed via cqe, and it is being handled by ublksrv, and
  94  * not committed yet
  95  *
  96  * Basically exclusively with UBLK_IO_FLAG_ACTIVE, so can be served for
  97  * cross verification
  98  */
  99 #define UBLK_IO_FLAG_OWNED_BY_SRV 0x02
 100
 101 /*
 102  * IO command is aborted, so this flag is set in case of
 103  * !UBLK_IO_FLAG_ACTIVE.
 104  *
 105  * After this flag is observed, any pending or new incoming request
 106  * associated with this io command will be failed immediately
 107  */
 108 #define UBLK_IO_FLAG_ABORTED 0x04
 109
 110 /*
 111  * UBLK_IO_FLAG_NEED_GET_DATA is set because IO command requires
 112  * get data buffer address from ublksrv.
 113  *
 114  * Then, bio data could be copied into this data buffer for a WRITE request
 115  * after the IO command is issued again and UBLK_IO_FLAG_NEED_GET_DATA is unset.
 116  */
 117 #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
 118
 119 /* atomic RW with ubq->cancel_lock */
 120 #define UBLK_IO_FLAG_CANCELED   0x80000000
 121
 122 struct ublk_io {
 123         /* userspace buffer address from io cmd */
 124         __u64   addr;
 125         unsigned int flags;
 126         int res;
 127
 128         struct io_uring_cmd *cmd;
 129 };
 130
 131 struct ublk_queue {
 132         int q_id;
 133         int q_depth;
 134
 135         unsigned long flags;
 136         struct task_struct      *ubq_daemon;
 137         char *io_cmd_buf;
 138
 139         struct llist_head       io_cmds;
 140
 141         unsigned long io_addr;  /* mapped vm address */
 142         unsigned int max_io_sz;
 143         bool force_abort;
 144         bool timeout;
 145         bool canceling;
 146         unsigned short nr_io_ready;     /* how many ios setup */
 147         spinlock_t              cancel_lock;
 148         struct ublk_device *dev;
 149         struct ublk_io ios[];
 150 };
 151
 152 struct ublk_device {
 153         struct gendisk          *ub_disk;
 154
 155         char    *__queues;
 156
 157         unsigned int    queue_size;
 158         struct ublksrv_ctrl_dev_info    dev_info;
 159
 160         struct blk_mq_tag_set   tag_set;
 161
 162         struct cdev             cdev;
 163         struct device           cdev_dev;
 164
 165 #define UB_STATE_OPEN           0
 166 #define UB_STATE_USED           1
 167 #define UB_STATE_DELETED        2
 168         unsigned long           state;
 169         int                     ub_number;
 170
 171         struct mutex            mutex;
 172
 173         spinlock_t              lock;
 174         struct mm_struct        *mm;
 175
 176         struct ublk_params      params;
 177
 178         struct completion       completion;
 179         unsigned int            nr_queues_ready;
 180         unsigned int            nr_privileged_daemon;
 181
 182         struct work_struct      quiesce_work;
 183         struct work_struct      stop_work;
 184 };
 185
 186 /* header of ublk_params */
 187 struct ublk_params_header {
 188         __u32   len;
 189         __u32   types;
 190 };
 191
 192 static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq);
 193
 194 static inline unsigned int ublk_req_build_flags(struct request *req);
 195 static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq,
 196                                                    int tag);
 197 static inline bool ublk_dev_is_user_copy(const struct ublk_device *ub)
 198 {
 199         return ub->dev_info.flags & UBLK_F_USER_COPY;
 200 }
 201
 202 static inline bool ublk_dev_is_zoned(const struct ublk_device *ub)
 203 {
 204         return ub->dev_info.flags & UBLK_F_ZONED;
 205 }
 206
 207 static inline bool ublk_queue_is_zoned(struct ublk_queue *ubq)
 208 {
 209         return ubq->flags & UBLK_F_ZONED;
 210 }
 211
 212 #ifdef CONFIG_BLK_DEV_ZONED
 213
 214 static int ublk_get_nr_zones(const struct ublk_device *ub)
 215 {
 216         const struct ublk_param_basic *p = &ub->params.basic;
 217
 218         /* Zone size is a power of 2 */
 219         return p->dev_sectors >> ilog2(p->chunk_sectors);
 220 }
 221
 222 static int ublk_revalidate_disk_zones(struct ublk_device *ub)
 223 {
 224         return blk_revalidate_disk_zones(ub->ub_disk, NULL);
 225 }
 226
 227 static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
 228 {
 229         const struct ublk_param_zoned *p = &ub->params.zoned;
 230         int nr_zones;
 231
 232         if (!ublk_dev_is_zoned(ub))
 233                 return -EINVAL;
 234
 235         if (!p->max_zone_append_sectors)
 236                 return -EINVAL;
 237
 238         nr_zones = ublk_get_nr_zones(ub);
 239
 240         if (p->max_active_zones > nr_zones)
 241                 return -EINVAL;
 242
 243         if (p->max_open_zones > nr_zones)
 244                 return -EINVAL;
 245
 246         return 0;
 247 }
 248
 249 static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
 250 {
 251         const struct ublk_param_zoned *p = &ub->params.zoned;
 252
 253         disk_set_zoned(ub->ub_disk);
 254         blk_queue_flag_set(QUEUE_FLAG_ZONE_RESETALL, ub->ub_disk->queue);
 255         blk_queue_required_elevator_features(ub->ub_disk->queue,
 256                                              ELEVATOR_F_ZBD_SEQ_WRITE);
 257         disk_set_max_active_zones(ub->ub_disk, p->max_active_zones);
 258         disk_set_max_open_zones(ub->ub_disk, p->max_open_zones);
 259         blk_queue_max_zone_append_sectors(ub->ub_disk->queue, p->max_zone_append_sectors);
 260
 261         ub->ub_disk->nr_zones = ublk_get_nr_zones(ub);
 262
 263         return 0;
 264 }
 265
 266 /* Based on virtblk_alloc_report_buffer */
 267 static void *ublk_alloc_report_buffer(struct ublk_device *ublk,
 268                                       unsigned int nr_zones, size_t *buflen)
 269 {
 270         struct request_queue *q = ublk->ub_disk->queue;
 271         size_t bufsize;
 272         void *buf;
 273
 274         nr_zones = min_t(unsigned int, nr_zones,
 275                          ublk->ub_disk->nr_zones);
 276
 277         bufsize = nr_zones * sizeof(struct blk_zone);
 278         bufsize =
 279                 min_t(size_t, bufsize, queue_max_hw_sectors(q) << SECTOR_SHIFT);
 280
 281         while (bufsize >= sizeof(struct blk_zone)) {
 282                 buf = kvmalloc(bufsize, GFP_KERNEL | __GFP_NORETRY);
 283                 if (buf) {
 284                         *buflen = bufsize;
 285                         return buf;
 286                 }
 287                 bufsize >>= 1;
 288         }
 289
 290         *buflen = 0;
 291         return NULL;
 292 }
 293
 294 static int ublk_report_zones(struct gendisk *disk, sector_t sector,
 295                       unsigned int nr_zones, report_zones_cb cb, void *data)
 296 {
 297         struct ublk_device *ub = disk->private_data;
 298         unsigned int zone_size_sectors = disk->queue->limits.chunk_sectors;
 299         unsigned int first_zone = sector >> ilog2(zone_size_sectors);
 300         unsigned int done_zones = 0;
 301         unsigned int max_zones_per_request;
 302         int ret;
 303         struct blk_zone *buffer;
 304         size_t buffer_length;
 305
 306         nr_zones = min_t(unsigned int, ub->ub_disk->nr_zones - first_zone,
 307                          nr_zones);
 308
 309         buffer = ublk_alloc_report_buffer(ub, nr_zones, &buffer_length);
 310         if (!buffer)
 311                 return -ENOMEM;
 312
 313         max_zones_per_request = buffer_length / sizeof(struct blk_zone);
 314
 315         while (done_zones < nr_zones) {
 316                 unsigned int remaining_zones = nr_zones - done_zones;
 317                 unsigned int zones_in_request =
 318                         min_t(unsigned int, remaining_zones, max_zones_per_request);
 319                 struct request *req;
 320                 struct ublk_rq_data *pdu;
 321                 blk_status_t status;
 322
 323                 memset(buffer, 0, buffer_length);
 324
 325                 req = blk_mq_alloc_request(disk->queue, REQ_OP_DRV_IN, 0);
 326                 if (IS_ERR(req)) {
 327                         ret = PTR_ERR(req);
 328                         goto out;
 329                 }
 330
 331                 pdu = blk_mq_rq_to_pdu(req);
 332                 pdu->operation = UBLK_IO_OP_REPORT_ZONES;
 333                 pdu->sector = sector;
 334                 pdu->nr_zones = zones_in_request;
 335
 336                 ret = blk_rq_map_kern(disk->queue, req, buffer, buffer_length,
 337                                         GFP_KERNEL);
 338                 if (ret) {
 339                         blk_mq_free_request(req);
 340                         goto out;
 341                 }
 342
 343                 status = blk_execute_rq(req, 0);
 344                 ret = blk_status_to_errno(status);
 345                 blk_mq_free_request(req);
 346                 if (ret)
 347                         goto out;
 348
 349                 for (unsigned int i = 0; i < zones_in_request; i++) {
 350                         struct blk_zone *zone = buffer + i;
 351
 352                         /* A zero length zone means no more zones in this response */
 353                         if (!zone->len)
 354                                 break;
 355
 356                         ret = cb(zone, i, data);
 357                         if (ret)
 358                                 goto out;
 359
 360                         done_zones++;
 361                         sector += zone_size_sectors;
 362
 363                 }
 364         }
 365
 366         ret = done_zones;
 367
 368 out:
 369         kvfree(buffer);
 370         return ret;
 371 }
 372
 373 static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
 374                                          struct request *req)
 375 {
 376         struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
 377         struct ublk_io *io = &ubq->ios[req->tag];
 378         struct ublk_rq_data *pdu = blk_mq_rq_to_pdu(req);
 379         u32 ublk_op;
 380
 381         switch (req_op(req)) {
 382         case REQ_OP_ZONE_OPEN:
 383                 ublk_op = UBLK_IO_OP_ZONE_OPEN;
 384                 break;
 385         case REQ_OP_ZONE_CLOSE:
 386                 ublk_op = UBLK_IO_OP_ZONE_CLOSE;
 387                 break;
 388         case REQ_OP_ZONE_FINISH:
 389                 ublk_op = UBLK_IO_OP_ZONE_FINISH;
 390                 break;
 391         case REQ_OP_ZONE_RESET:
 392                 ublk_op = UBLK_IO_OP_ZONE_RESET;
 393                 break;
 394         case REQ_OP_ZONE_APPEND:
 395                 ublk_op = UBLK_IO_OP_ZONE_APPEND;
 396                 break;
 397         case REQ_OP_ZONE_RESET_ALL:
 398                 ublk_op = UBLK_IO_OP_ZONE_RESET_ALL;
 399                 break;
 400         case REQ_OP_DRV_IN:
 401                 ublk_op = pdu->operation;
 402                 switch (ublk_op) {
 403                 case UBLK_IO_OP_REPORT_ZONES:
 404                         iod->op_flags = ublk_op | ublk_req_build_flags(req);
 405                         iod->nr_zones = pdu->nr_zones;
 406                         iod->start_sector = pdu->sector;
 407                         return BLK_STS_OK;
 408                 default:
 409                         return BLK_STS_IOERR;
 410                 }
 411         case REQ_OP_DRV_OUT:
 412                 /* We do not support drv_out */
 413                 return BLK_STS_NOTSUPP;
 414         default:
 415                 return BLK_STS_IOERR;
 416         }
 417
 418         iod->op_flags = ublk_op | ublk_req_build_flags(req);
 419         iod->nr_sectors = blk_rq_sectors(req);
 420         iod->start_sector = blk_rq_pos(req);
 421         iod->addr = io->addr;
 422
 423         return BLK_STS_OK;
 424 }
 425
 426 #else
 427
 428 #define ublk_report_zones (NULL)
 429
 430 static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
 431 {
 432         return -EOPNOTSUPP;
 433 }
 434
 435 static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
 436 {
 437         return -EOPNOTSUPP;
 438 }
 439
 440 static int ublk_revalidate_disk_zones(struct ublk_device *ub)
 441 {
 442         return 0;
 443 }
 444
 445 static blk_status_t ublk_setup_iod_zoned(struct ublk_queue *ubq,
 446                                          struct request *req)
 447 {
 448         return BLK_STS_NOTSUPP;
 449 }
 450
 451 #endif
 452
 453 static inline void __ublk_complete_rq(struct request *req);
 454 static void ublk_complete_rq(struct kref *ref);
 455
 456 static dev_t ublk_chr_devt;
 457 static const struct class ublk_chr_class = {
 458         .name = "ublk-char",
 459 };
 460
 461 static DEFINE_IDR(ublk_index_idr);
 462 static DEFINE_SPINLOCK(ublk_idr_lock);
 463 static wait_queue_head_t ublk_idr_wq;   /* wait until one idr is freed */
 464
 465 static DEFINE_MUTEX(ublk_ctl_mutex);
 466
 467 /*
 468  * Max ublk devices allowed to add
 469  *
 470  * It can be extended to one per-user limit in future or even controlled
 471  * by cgroup.
 472  */
 473 #define UBLK_MAX_UBLKS UBLK_MINORS
 474 static unsigned int ublks_max = 64;
 475 static unsigned int ublks_added;        /* protected by ublk_ctl_mutex */
 476
 477 static struct miscdevice ublk_misc;
 478
 479 static inline unsigned ublk_pos_to_hwq(loff_t pos)
 480 {
 481         return ((pos - UBLKSRV_IO_BUF_OFFSET) >> UBLK_QID_OFF) &
 482                 UBLK_QID_BITS_MASK;
 483 }
 484
 485 static inline unsigned ublk_pos_to_buf_off(loff_t pos)
 486 {
 487         return (pos - UBLKSRV_IO_BUF_OFFSET) & UBLK_IO_BUF_BITS_MASK;
 488 }
 489
 490 static inline unsigned ublk_pos_to_tag(loff_t pos)
 491 {
 492         return ((pos - UBLKSRV_IO_BUF_OFFSET) >> UBLK_TAG_OFF) &
 493                 UBLK_TAG_BITS_MASK;
 494 }
 495
 496 static void ublk_dev_param_basic_apply(struct ublk_device *ub)
 497 {
 498         struct request_queue *q = ub->ub_disk->queue;
 499         const struct ublk_param_basic *p = &ub->params.basic;
 500
 501         blk_queue_logical_block_size(q, 1 << p->logical_bs_shift);
 502         blk_queue_physical_block_size(q, 1 << p->physical_bs_shift);
 503         blk_queue_io_min(q, 1 << p->io_min_shift);
 504         blk_queue_io_opt(q, 1 << p->io_opt_shift);
 505
 506         blk_queue_write_cache(q, p->attrs & UBLK_ATTR_VOLATILE_CACHE,
 507                         p->attrs & UBLK_ATTR_FUA);
 508         if (p->attrs & UBLK_ATTR_ROTATIONAL)
 509                 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
 510         else
 511                 blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
 512
 513         blk_queue_max_hw_sectors(q, p->max_sectors);
 514         blk_queue_chunk_sectors(q, p->chunk_sectors);
 515         blk_queue_virt_boundary(q, p->virt_boundary_mask);
 516
 517         if (p->attrs & UBLK_ATTR_READ_ONLY)
 518                 set_disk_ro(ub->ub_disk, true);
 519
 520         set_capacity(ub->ub_disk, p->dev_sectors);
 521 }
 522
 523 static void ublk_dev_param_discard_apply(struct ublk_device *ub)
 524 {
 525         struct request_queue *q = ub->ub_disk->queue;
 526         const struct ublk_param_discard *p = &ub->params.discard;
 527
 528         q->limits.discard_alignment = p->discard_alignment;
 529         q->limits.discard_granularity = p->discard_granularity;
 530         blk_queue_max_discard_sectors(q, p->max_discard_sectors);
 531         blk_queue_max_write_zeroes_sectors(q,
 532                         p->max_write_zeroes_sectors);
 533         blk_queue_max_discard_segments(q, p->max_discard_segments);
 534 }
 535
 536 static int ublk_validate_params(const struct ublk_device *ub)
 537 {
 538         /* basic param is the only one which must be set */
 539         if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
 540                 const struct ublk_param_basic *p = &ub->params.basic;
 541
 542                 if (p->logical_bs_shift > PAGE_SHIFT || p->logical_bs_shift < 9)
 543                         return -EINVAL;
 544
 545                 if (p->logical_bs_shift > p->physical_bs_shift)
 546                         return -EINVAL;
 547
 548                 if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
 549                         return -EINVAL;
 550
 551                 if (ublk_dev_is_zoned(ub) && !p->chunk_sectors)
 552                         return -EINVAL;
 553         } else
 554                 return -EINVAL;
 555
 556         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD) {
 557                 const struct ublk_param_discard *p = &ub->params.discard;
 558
 559                 /* So far, only support single segment discard */
 560                 if (p->max_discard_sectors && p->max_discard_segments != 1)
 561                         return -EINVAL;
 562
 563                 if (!p->discard_granularity)
 564                         return -EINVAL;
 565         }
 566
 567         /* dev_t is read-only */
 568         if (ub->params.types & UBLK_PARAM_TYPE_DEVT)
 569                 return -EINVAL;
 570
 571         if (ub->params.types & UBLK_PARAM_TYPE_ZONED)
 572                 return ublk_dev_param_zoned_validate(ub);
 573         else if (ublk_dev_is_zoned(ub))
 574                 return -EINVAL;
 575
 576         return 0;
 577 }
 578
 579 static int ublk_apply_params(struct ublk_device *ub)
 580 {
 581         if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
 582                 return -EINVAL;
 583
 584         ublk_dev_param_basic_apply(ub);
 585
 586         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
 587                 ublk_dev_param_discard_apply(ub);
 588
 589         if (ub->params.types & UBLK_PARAM_TYPE_ZONED)
 590                 return ublk_dev_param_zoned_apply(ub);
 591
 592         return 0;
 593 }
 594
 595 static inline bool ublk_support_user_copy(const struct ublk_queue *ubq)
 596 {
 597         return ubq->flags & UBLK_F_USER_COPY;
 598 }
 599
 600 static inline bool ublk_need_req_ref(const struct ublk_queue *ubq)
 601 {
 602         /*
 603          * read()/write() is involved in user copy, so request reference
 604          * has to be grabbed
 605          */
 606         return ublk_support_user_copy(ubq);
 607 }
 608
 609 static inline void ublk_init_req_ref(const struct ublk_queue *ubq,
 610                 struct request *req)
 611 {
 612         if (ublk_need_req_ref(ubq)) {
 613                 struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 614
 615                 kref_init(&data->ref);
 616         }
 617 }
 618
 619 static inline bool ublk_get_req_ref(const struct ublk_queue *ubq,
 620                 struct request *req)
 621 {
 622         if (ublk_need_req_ref(ubq)) {
 623                 struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 624
 625                 return kref_get_unless_zero(&data->ref);
 626         }
 627
 628         return true;
 629 }
 630
 631 static inline void ublk_put_req_ref(const struct ublk_queue *ubq,
 632                 struct request *req)
 633 {
 634         if (ublk_need_req_ref(ubq)) {
 635                 struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 636
 637                 kref_put(&data->ref, ublk_complete_rq);
 638         } else {
 639                 __ublk_complete_rq(req);
 640         }
 641 }
 642
 643 static inline bool ublk_need_get_data(const struct ublk_queue *ubq)
 644 {
 645         return ubq->flags & UBLK_F_NEED_GET_DATA;
 646 }
 647
 648 static struct ublk_device *ublk_get_device(struct ublk_device *ub)
 649 {
 650         if (kobject_get_unless_zero(&ub->cdev_dev.kobj))
 651                 return ub;
 652         return NULL;
 653 }
 654
 655 static void ublk_put_device(struct ublk_device *ub)
 656 {
 657         put_device(&ub->cdev_dev);
 658 }
 659
 660 static inline struct ublk_queue *ublk_get_queue(struct ublk_device *dev,
 661                 int qid)
 662 {
 663        return (struct ublk_queue *)&(dev->__queues[qid * dev->queue_size]);
 664 }
 665
 666 static inline bool ublk_rq_has_data(const struct request *rq)
 667 {
 668         return bio_has_data(rq->bio);
 669 }
 670
 671 static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq,
 672                 int tag)
 673 {
 674         return (struct ublksrv_io_desc *)
 675                 &(ubq->io_cmd_buf[tag * sizeof(struct ublksrv_io_desc)]);
 676 }
 677
 678 static inline char *ublk_queue_cmd_buf(struct ublk_device *ub, int q_id)
 679 {
 680         return ublk_get_queue(ub, q_id)->io_cmd_buf;
 681 }
 682
 683 static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
 684 {
 685         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 686
 687         return round_up(ubq->q_depth * sizeof(struct ublksrv_io_desc),
 688                         PAGE_SIZE);
 689 }
 690
 691 static inline bool ublk_queue_can_use_recovery_reissue(
 692                 struct ublk_queue *ubq)
 693 {
 694         return (ubq->flags & UBLK_F_USER_RECOVERY) &&
 695                         (ubq->flags & UBLK_F_USER_RECOVERY_REISSUE);
 696 }
 697
 698 static inline bool ublk_queue_can_use_recovery(
 699                 struct ublk_queue *ubq)
 700 {
 701         return ubq->flags & UBLK_F_USER_RECOVERY;
 702 }
 703
 704 static inline bool ublk_can_use_recovery(struct ublk_device *ub)
 705 {
 706         return ub->dev_info.flags & UBLK_F_USER_RECOVERY;
 707 }
 708
 709 static void ublk_free_disk(struct gendisk *disk)
 710 {
 711         struct ublk_device *ub = disk->private_data;
 712
 713         clear_bit(UB_STATE_USED, &ub->state);
 714         put_device(&ub->cdev_dev);
 715 }
 716
 717 static void ublk_store_owner_uid_gid(unsigned int *owner_uid,
 718                 unsigned int *owner_gid)
 719 {
 720         kuid_t uid;
 721         kgid_t gid;
 722
 723         current_uid_gid(&uid, &gid);
 724
 725         *owner_uid = from_kuid(&init_user_ns, uid);
 726         *owner_gid = from_kgid(&init_user_ns, gid);
 727 }
 728
 729 static int ublk_open(struct gendisk *disk, blk_mode_t mode)
 730 {
 731         struct ublk_device *ub = disk->private_data;
 732
 733         if (capable(CAP_SYS_ADMIN))
 734                 return 0;
 735
 736         /*
 737          * If it is one unprivileged device, only owner can open
 738          * the disk. Otherwise it could be one trap made by one
 739          * evil user who grants this disk's privileges to other
 740          * users deliberately.
 741          *
 742          * This way is reasonable too given anyone can create
 743          * unprivileged device, and no need other's grant.
 744          */
 745         if (ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV) {
 746                 unsigned int curr_uid, curr_gid;
 747
 748                 ublk_store_owner_uid_gid(&curr_uid, &curr_gid);
 749
 750                 if (curr_uid != ub->dev_info.owner_uid || curr_gid !=
 751                                 ub->dev_info.owner_gid)
 752                         return -EPERM;
 753         }
 754
 755         return 0;
 756 }
 757
 758 static const struct block_device_operations ub_fops = {
 759         .owner =        THIS_MODULE,
 760         .open =         ublk_open,
 761         .free_disk =    ublk_free_disk,
 762         .report_zones = ublk_report_zones,
 763 };
 764
 765 #define UBLK_MAX_PIN_PAGES      32
 766
 767 struct ublk_io_iter {
 768         struct page *pages[UBLK_MAX_PIN_PAGES];
 769         struct bio *bio;
 770         struct bvec_iter iter;
 771 };
 772
 773 /* return how many pages are copied */
 774 static void ublk_copy_io_pages(struct ublk_io_iter *data,
 775                 size_t total, size_t pg_off, int dir)
 776 {
 777         unsigned done = 0;
 778         unsigned pg_idx = 0;
 779
 780         while (done < total) {
 781                 struct bio_vec bv = bio_iter_iovec(data->bio, data->iter);
 782                 unsigned int bytes = min3(bv.bv_len, (unsigned)total - done,
 783                                 (unsigned)(PAGE_SIZE - pg_off));
 784                 void *bv_buf = bvec_kmap_local(&bv);
 785                 void *pg_buf = kmap_local_page(data->pages[pg_idx]);
 786
 787                 if (dir == ITER_DEST)
 788                         memcpy(pg_buf + pg_off, bv_buf, bytes);
 789                 else
 790                         memcpy(bv_buf, pg_buf + pg_off, bytes);
 791
 792                 kunmap_local(pg_buf);
 793                 kunmap_local(bv_buf);
 794
 795                 /* advance page array */
 796                 pg_off += bytes;
 797                 if (pg_off == PAGE_SIZE) {
 798                         pg_idx += 1;
 799                         pg_off = 0;
 800                 }
 801
 802                 done += bytes;
 803
 804                 /* advance bio */
 805                 bio_advance_iter_single(data->bio, &data->iter, bytes);
 806                 if (!data->iter.bi_size) {
 807                         data->bio = data->bio->bi_next;
 808                         if (data->bio == NULL)
 809                                 break;
 810                         data->iter = data->bio->bi_iter;
 811                 }
 812         }
 813 }
 814
 815 static bool ublk_advance_io_iter(const struct request *req,
 816                 struct ublk_io_iter *iter, unsigned int offset)
 817 {
 818         struct bio *bio = req->bio;
 819
 820         for_each_bio(bio) {
 821                 if (bio->bi_iter.bi_size > offset) {
 822                         iter->bio = bio;
 823                         iter->iter = bio->bi_iter;
 824                         bio_advance_iter(iter->bio, &iter->iter, offset);
 825                         return true;
 826                 }
 827                 offset -= bio->bi_iter.bi_size;
 828         }
 829         return false;
 830 }
 831
 832 /*
 833  * Copy data between request pages and io_iter, and 'offset'
 834  * is the start point of linear offset of request.
 835  */
 836 static size_t ublk_copy_user_pages(const struct request *req,
 837                 unsigned offset, struct iov_iter *uiter, int dir)
 838 {
 839         struct ublk_io_iter iter;
 840         size_t done = 0;
 841
 842         if (!ublk_advance_io_iter(req, &iter, offset))
 843                 return 0;
 844
 845         while (iov_iter_count(uiter) && iter.bio) {
 846                 unsigned nr_pages;
 847                 ssize_t len;
 848                 size_t off;
 849                 int i;
 850
 851                 len = iov_iter_get_pages2(uiter, iter.pages,
 852                                 iov_iter_count(uiter),
 853                                 UBLK_MAX_PIN_PAGES, &off);
 854                 if (len <= 0)
 855                         return done;
 856
 857                 ublk_copy_io_pages(&iter, len, off, dir);
 858                 nr_pages = DIV_ROUND_UP(len + off, PAGE_SIZE);
 859                 for (i = 0; i < nr_pages; i++) {
 860                         if (dir == ITER_DEST)
 861                                 set_page_dirty(iter.pages[i]);
 862                         put_page(iter.pages[i]);
 863                 }
 864                 done += len;
 865         }
 866
 867         return done;
 868 }
 869
 870 static inline bool ublk_need_map_req(const struct request *req)
 871 {
 872         return ublk_rq_has_data(req) && req_op(req) == REQ_OP_WRITE;
 873 }
 874
 875 static inline bool ublk_need_unmap_req(const struct request *req)
 876 {
 877         return ublk_rq_has_data(req) &&
 878                (req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_DRV_IN);
 879 }
 880
 881 static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
 882                 struct ublk_io *io)
 883 {
 884         const unsigned int rq_bytes = blk_rq_bytes(req);
 885
 886         if (ublk_support_user_copy(ubq))
 887                 return rq_bytes;
 888
 889         /*
 890          * no zero copy, we delay copy WRITE request data into ublksrv
 891          * context and the big benefit is that pinning pages in current
 892          * context is pretty fast, see ublk_pin_user_pages
 893          */
 894         if (ublk_need_map_req(req)) {
 895                 struct iov_iter iter;
 896                 const int dir = ITER_DEST;
 897
 898                 import_ubuf(dir, u64_to_user_ptr(io->addr), rq_bytes, &iter);
 899                 return ublk_copy_user_pages(req, 0, &iter, dir);
 900         }
 901         return rq_bytes;
 902 }
 903
 904 static int ublk_unmap_io(const struct ublk_queue *ubq,
 905                 const struct request *req,
 906                 struct ublk_io *io)
 907 {
 908         const unsigned int rq_bytes = blk_rq_bytes(req);
 909
 910         if (ublk_support_user_copy(ubq))
 911                 return rq_bytes;
 912
 913         if (ublk_need_unmap_req(req)) {
 914                 struct iov_iter iter;
 915                 const int dir = ITER_SOURCE;
 916
 917                 WARN_ON_ONCE(io->res > rq_bytes);
 918
 919                 import_ubuf(dir, u64_to_user_ptr(io->addr), io->res, &iter);
 920                 return ublk_copy_user_pages(req, 0, &iter, dir);
 921         }
 922         return rq_bytes;
 923 }
 924
 925 static inline unsigned int ublk_req_build_flags(struct request *req)
 926 {
 927         unsigned flags = 0;
 928
 929         if (req->cmd_flags & REQ_FAILFAST_DEV)
 930                 flags |= UBLK_IO_F_FAILFAST_DEV;
 931
 932         if (req->cmd_flags & REQ_FAILFAST_TRANSPORT)
 933                 flags |= UBLK_IO_F_FAILFAST_TRANSPORT;
 934
 935         if (req->cmd_flags & REQ_FAILFAST_DRIVER)
 936                 flags |= UBLK_IO_F_FAILFAST_DRIVER;
 937
 938         if (req->cmd_flags & REQ_META)
 939                 flags |= UBLK_IO_F_META;
 940
 941         if (req->cmd_flags & REQ_FUA)
 942                 flags |= UBLK_IO_F_FUA;
 943
 944         if (req->cmd_flags & REQ_NOUNMAP)
 945                 flags |= UBLK_IO_F_NOUNMAP;
 946
 947         if (req->cmd_flags & REQ_SWAP)
 948                 flags |= UBLK_IO_F_SWAP;
 949
 950         return flags;
 951 }
 952
 953 static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 954 {
 955         struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
 956         struct ublk_io *io = &ubq->ios[req->tag];
 957         enum req_op op = req_op(req);
 958         u32 ublk_op;
 959
 960         if (!ublk_queue_is_zoned(ubq) &&
 961             (op_is_zone_mgmt(op) || op == REQ_OP_ZONE_APPEND))
 962                 return BLK_STS_IOERR;
 963
 964         switch (req_op(req)) {
 965         case REQ_OP_READ:
 966                 ublk_op = UBLK_IO_OP_READ;
 967                 break;
 968         case REQ_OP_WRITE:
 969                 ublk_op = UBLK_IO_OP_WRITE;
 970                 break;
 971         case REQ_OP_FLUSH:
 972                 ublk_op = UBLK_IO_OP_FLUSH;
 973                 break;
 974         case REQ_OP_DISCARD:
 975                 ublk_op = UBLK_IO_OP_DISCARD;
 976                 break;
 977         case REQ_OP_WRITE_ZEROES:
 978                 ublk_op = UBLK_IO_OP_WRITE_ZEROES;
 979                 break;
 980         default:
 981                 if (ublk_queue_is_zoned(ubq))
 982                         return ublk_setup_iod_zoned(ubq, req);
 983                 return BLK_STS_IOERR;
 984         }
 985
 986         /* need to translate since kernel may change */
 987         iod->op_flags = ublk_op | ublk_req_build_flags(req);
 988         iod->nr_sectors = blk_rq_sectors(req);
 989         iod->start_sector = blk_rq_pos(req);
 990         iod->addr = io->addr;
 991
 992         return BLK_STS_OK;
 993 }
 994
 995 static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu(
 996                 struct io_uring_cmd *ioucmd)
 997 {
 998         return (struct ublk_uring_cmd_pdu *)&ioucmd->pdu;
 999 }
1000
1001 static inline bool ubq_daemon_is_dying(struct ublk_queue *ubq)
1002 {
1003         return ubq->ubq_daemon->flags & PF_EXITING;
1004 }
1005
1006 /* todo: handle partial completion */
1007 static inline void __ublk_complete_rq(struct request *req)
1008 {
1009         struct ublk_queue *ubq = req->mq_hctx->driver_data;
1010         struct ublk_io *io = &ubq->ios[req->tag];
1011         unsigned int unmapped_bytes;
1012         blk_status_t res = BLK_STS_OK;
1013
1014         /* called from ublk_abort_queue() code path */
1015         if (io->flags & UBLK_IO_FLAG_ABORTED) {
1016                 res = BLK_STS_IOERR;
1017                 goto exit;
1018         }
1019
1020         /* failed read IO if nothing is read */
1021         if (!io->res && req_op(req) == REQ_OP_READ)
1022                 io->res = -EIO;
1023
1024         if (io->res < 0) {
1025                 res = errno_to_blk_status(io->res);
1026                 goto exit;
1027         }
1028
1029         /*
1030          * FLUSH, DISCARD or WRITE_ZEROES usually won't return bytes returned, so end them
1031          * directly.
1032          *
1033          * Both the two needn't unmap.
1034          */
1035         if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE &&
1036             req_op(req) != REQ_OP_DRV_IN)
1037                 goto exit;
1038
1039         /* for READ request, writing data in iod->addr to rq buffers */
1040         unmapped_bytes = ublk_unmap_io(ubq, req, io);
1041
1042         /*
1043          * Extremely impossible since we got data filled in just before
1044          *
1045          * Re-read simply for this unlikely case.
1046          */
1047         if (unlikely(unmapped_bytes < io->res))
1048                 io->res = unmapped_bytes;
1049
1050         if (blk_update_request(req, BLK_STS_OK, io->res))
1051                 blk_mq_requeue_request(req, true);
1052         else
1053                 __blk_mq_end_request(req, BLK_STS_OK);
1054
1055         return;
1056 exit:
1057         blk_mq_end_request(req, res);
1058 }
1059
1060 static void ublk_complete_rq(struct kref *ref)
1061 {
1062         struct ublk_rq_data *data = container_of(ref, struct ublk_rq_data,
1063                         ref);
1064         struct request *req = blk_mq_rq_from_pdu(data);
1065
1066         __ublk_complete_rq(req);
1067 }
1068
1069 /*
1070  * Since __ublk_rq_task_work always fails requests immediately during
1071  * exiting, __ublk_fail_req() is only called from abort context during
1072  * exiting. So lock is unnecessary.
1073  *
1074  * Also aborting may not be started yet, keep in mind that one failed
1075  * request may be issued by block layer again.
1076  */
1077 static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
1078                 struct request *req)
1079 {
1080         WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
1081
1082         if (ublk_queue_can_use_recovery_reissue(ubq))
1083                 blk_mq_requeue_request(req, false);
1084         else
1085                 ublk_put_req_ref(ubq, req);
1086 }
1087
1088 static void ubq_complete_io_cmd(struct ublk_io *io, int res,
1089                                 unsigned issue_flags)
1090 {
1091         /* mark this cmd owned by ublksrv */
1092         io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV;
1093
1094         /*
1095          * clear ACTIVE since we are done with this sqe/cmd slot
1096          * We can only accept io cmd in case of being not active.
1097          */
1098         io->flags &= ~UBLK_IO_FLAG_ACTIVE;
1099
1100         /* tell ublksrv one io request is coming */
1101         io_uring_cmd_done(io->cmd, res, 0, issue_flags);
1102 }
1103
1104 #define UBLK_REQUEUE_DELAY_MS   3
1105
1106 static inline void __ublk_abort_rq(struct ublk_queue *ubq,
1107                 struct request *rq)
1108 {
1109         /* We cannot process this rq so just requeue it. */
1110         if (ublk_queue_can_use_recovery(ubq))
1111                 blk_mq_requeue_request(rq, false);
1112         else
1113                 blk_mq_end_request(rq, BLK_STS_IOERR);
1114 }
1115
1116 static inline void __ublk_rq_task_work(struct request *req,
1117                                        unsigned issue_flags)
1118 {
1119         struct ublk_queue *ubq = req->mq_hctx->driver_data;
1120         int tag = req->tag;
1121         struct ublk_io *io = &ubq->ios[tag];
1122         unsigned int mapped_bytes;
1123
1124         pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",
1125                         __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
1126                         ublk_get_iod(ubq, req->tag)->addr);
1127
1128         /*
1129          * Task is exiting if either:
1130          *
1131          * (1) current != ubq_daemon.
1132          * io_uring_cmd_complete_in_task() tries to run task_work
1133          * in a workqueue if ubq_daemon(cmd's task) is PF_EXITING.
1134          *
1135          * (2) current->flags & PF_EXITING.
1136          */
1137         if (unlikely(current != ubq->ubq_daemon || current->flags & PF_EXITING)) {
1138                 __ublk_abort_rq(ubq, req);
1139                 return;
1140         }
1141
1142         if (ublk_need_get_data(ubq) && ublk_need_map_req(req)) {
1143                 /*
1144                  * We have not handled UBLK_IO_NEED_GET_DATA command yet,
1145                  * so immepdately pass UBLK_IO_RES_NEED_GET_DATA to ublksrv
1146                  * and notify it.
1147                  */
1148                 if (!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA)) {
1149                         io->flags |= UBLK_IO_FLAG_NEED_GET_DATA;
1150                         pr_devel("%s: need get data. op %d, qid %d tag %d io_flags %x\n",
1151                                         __func__, io->cmd->cmd_op, ubq->q_id,
1152                                         req->tag, io->flags);
1153                         ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA, issue_flags);
1154                         return;
1155                 }
1156                 /*
1157                  * We have handled UBLK_IO_NEED_GET_DATA command,
1158                  * so clear UBLK_IO_FLAG_NEED_GET_DATA now and just
1159                  * do the copy work.
1160                  */
1161                 io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA;
1162                 /* update iod->addr because ublksrv may have passed a new io buffer */
1163                 ublk_get_iod(ubq, req->tag)->addr = io->addr;
1164                 pr_devel("%s: update iod->addr: op %d, qid %d tag %d io_flags %x addr %llx\n",
1165                                 __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
1166                                 ublk_get_iod(ubq, req->tag)->addr);
1167         }
1168
1169         mapped_bytes = ublk_map_io(ubq, req, io);
1170
1171         /* partially mapped, update io descriptor */
1172         if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
1173                 /*
1174                  * Nothing mapped, retry until we succeed.
1175                  *
1176                  * We may never succeed in mapping any bytes here because
1177                  * of OOM. TODO: reserve one buffer with single page pinned
1178                  * for providing forward progress guarantee.
1179                  */
1180                 if (unlikely(!mapped_bytes)) {
1181                         blk_mq_requeue_request(req, false);
1182                         blk_mq_delay_kick_requeue_list(req->q,
1183                                         UBLK_REQUEUE_DELAY_MS);
1184                         return;
1185                 }
1186
1187                 ublk_get_iod(ubq, req->tag)->nr_sectors =
1188                         mapped_bytes >> 9;
1189         }
1190
1191         ublk_init_req_ref(ubq, req);
1192         ubq_complete_io_cmd(io, UBLK_IO_RES_OK, issue_flags);
1193 }
1194
1195 static inline void ublk_forward_io_cmds(struct ublk_queue *ubq,
1196                                         unsigned issue_flags)
1197 {
1198         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
1199         struct ublk_rq_data *data, *tmp;
1200
1201         io_cmds = llist_reverse_order(io_cmds);
1202         llist_for_each_entry_safe(data, tmp, io_cmds, node)
1203                 __ublk_rq_task_work(blk_mq_rq_from_pdu(data), issue_flags);
1204 }
1205
1206 static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd, unsigned issue_flags)
1207 {
1208         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
1209         struct ublk_queue *ubq = pdu->ubq;
1210
1211         ublk_forward_io_cmds(ubq, issue_flags);
1212 }
1213
1214 static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq)
1215 {
1216         struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
1217
1218         if (llist_add(&data->node, &ubq->io_cmds)) {
1219                 struct ublk_io *io = &ubq->ios[rq->tag];
1220
1221                 io_uring_cmd_complete_in_task(io->cmd, ublk_rq_task_work_cb);
1222         }
1223 }
1224
1225 static enum blk_eh_timer_return ublk_timeout(struct request *rq)
1226 {
1227         struct ublk_queue *ubq = rq->mq_hctx->driver_data;
1228         unsigned int nr_inflight = 0;
1229         int i;
1230
1231         if (ubq->flags & UBLK_F_UNPRIVILEGED_DEV) {
1232                 if (!ubq->timeout) {
1233                         send_sig(SIGKILL, ubq->ubq_daemon, 0);
1234                         ubq->timeout = true;
1235                 }
1236
1237                 return BLK_EH_DONE;
1238         }
1239
1240         if (!ubq_daemon_is_dying(ubq))
1241                 return BLK_EH_RESET_TIMER;
1242
1243         for (i = 0; i < ubq->q_depth; i++) {
1244                 struct ublk_io *io = &ubq->ios[i];
1245
1246                 if (!(io->flags & UBLK_IO_FLAG_ACTIVE))
1247                         nr_inflight++;
1248         }
1249
1250         /* cancelable uring_cmd can't help us if all commands are in-flight */
1251         if (nr_inflight == ubq->q_depth) {
1252                 struct ublk_device *ub = ubq->dev;
1253
1254                 if (ublk_abort_requests(ub, ubq)) {
1255                         if (ublk_can_use_recovery(ub))
1256                                 schedule_work(&ub->quiesce_work);
1257                         else
1258                                 schedule_work(&ub->stop_work);
1259                 }
1260                 return BLK_EH_DONE;
1261         }
1262
1263         return BLK_EH_RESET_TIMER;
1264 }
1265
1266 static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
1267                 const struct blk_mq_queue_data *bd)
1268 {
1269         struct ublk_queue *ubq = hctx->driver_data;
1270         struct request *rq = bd->rq;
1271         blk_status_t res;
1272
1273         /* fill iod to slot in io cmd buffer */
1274         res = ublk_setup_iod(ubq, rq);
1275         if (unlikely(res != BLK_STS_OK))
1276                 return BLK_STS_IOERR;
1277
1278         /* With recovery feature enabled, force_abort is set in
1279          * ublk_stop_dev() before calling del_gendisk(). We have to
1280          * abort all requeued and new rqs here to let del_gendisk()
1281          * move on. Besides, we cannot not call io_uring_cmd_complete_in_task()
1282          * to avoid UAF on io_uring ctx.
1283          *
1284          * Note: force_abort is guaranteed to be seen because it is set
1285          * before request queue is unqiuesced.
1286          */
1287         if (ublk_queue_can_use_recovery(ubq) && unlikely(ubq->force_abort))
1288                 return BLK_STS_IOERR;
1289
1290         if (unlikely(ubq->canceling)) {
1291                 __ublk_abort_rq(ubq, rq);
1292                 return BLK_STS_OK;
1293         }
1294
1295         blk_mq_start_request(bd->rq);
1296         ublk_queue_cmd(ubq, rq);
1297
1298         return BLK_STS_OK;
1299 }
1300
1301 static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
1302                 unsigned int hctx_idx)
1303 {
1304         struct ublk_device *ub = driver_data;
1305         struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num);
1306
1307         hctx->driver_data = ubq;
1308         return 0;
1309 }
1310
1311 static const struct blk_mq_ops ublk_mq_ops = {
1312         .queue_rq       = ublk_queue_rq,
1313         .init_hctx      = ublk_init_hctx,
1314         .timeout        = ublk_timeout,
1315 };
1316
1317 static int ublk_ch_open(struct inode *inode, struct file *filp)
1318 {
1319         struct ublk_device *ub = container_of(inode->i_cdev,
1320                         struct ublk_device, cdev);
1321
1322         if (test_and_set_bit(UB_STATE_OPEN, &ub->state))
1323                 return -EBUSY;
1324         filp->private_data = ub;
1325         return 0;
1326 }
1327
1328 static int ublk_ch_release(struct inode *inode, struct file *filp)
1329 {
1330         struct ublk_device *ub = filp->private_data;
1331
1332         clear_bit(UB_STATE_OPEN, &ub->state);
1333         return 0;
1334 }
1335
1336 /* map pre-allocated per-queue cmd buffer to ublksrv daemon */
1337 static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
1338 {
1339         struct ublk_device *ub = filp->private_data;
1340         size_t sz = vma->vm_end - vma->vm_start;
1341         unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc);
1342         unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT;
1343         int q_id, ret = 0;
1344
1345         spin_lock(&ub->lock);
1346         if (!ub->mm)
1347                 ub->mm = current->mm;
1348         if (current->mm != ub->mm)
1349                 ret = -EINVAL;
1350         spin_unlock(&ub->lock);
1351
1352         if (ret)
1353                 return ret;
1354
1355         if (vma->vm_flags & VM_WRITE)
1356                 return -EPERM;
1357
1358         end = UBLKSRV_CMD_BUF_OFFSET + ub->dev_info.nr_hw_queues * max_sz;
1359         if (phys_off < UBLKSRV_CMD_BUF_OFFSET || phys_off >= end)
1360                 return -EINVAL;
1361
1362         q_id = (phys_off - UBLKSRV_CMD_BUF_OFFSET) / max_sz;
1363         pr_devel("%s: qid %d, pid %d, addr %lx pg_off %lx sz %lu\n",
1364                         __func__, q_id, current->pid, vma->vm_start,
1365                         phys_off, (unsigned long)sz);
1366
1367         if (sz != ublk_queue_cmd_buf_size(ub, q_id))
1368                 return -EINVAL;
1369
1370         pfn = virt_to_phys(ublk_queue_cmd_buf(ub, q_id)) >> PAGE_SHIFT;
1371         return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
1372 }
1373
1374 static void ublk_commit_completion(struct ublk_device *ub,
1375                 const struct ublksrv_io_cmd *ub_cmd)
1376 {
1377         u32 qid = ub_cmd->q_id, tag = ub_cmd->tag;
1378         struct ublk_queue *ubq = ublk_get_queue(ub, qid);
1379         struct ublk_io *io = &ubq->ios[tag];
1380         struct request *req;
1381
1382         /* now this cmd slot is owned by nbd driver */
1383         io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
1384         io->res = ub_cmd->result;
1385
1386         /* find the io request and complete */
1387         req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
1388         if (WARN_ON_ONCE(unlikely(!req)))
1389                 return;
1390
1391         if (req_op(req) == REQ_OP_ZONE_APPEND)
1392                 req->__sector = ub_cmd->zone_append_lba;
1393
1394         if (likely(!blk_should_fake_timeout(req->q)))
1395                 ublk_put_req_ref(ubq, req);
1396 }
1397
1398 /*
1399  * Called from ubq_daemon context via cancel fn, meantime quiesce ublk
1400  * blk-mq queue, so we are called exclusively with blk-mq and ubq_daemon
1401  * context, so everything is serialized.
1402  */
1403 static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
1404 {
1405         int i;
1406
1407         for (i = 0; i < ubq->q_depth; i++) {
1408                 struct ublk_io *io = &ubq->ios[i];
1409
1410                 if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) {
1411                         struct request *rq;
1412
1413                         /*
1414                          * Either we fail the request or ublk_rq_task_work_fn
1415                          * will do it
1416                          */
1417                         rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);
1418                         if (rq && blk_mq_request_started(rq)) {
1419                                 io->flags |= UBLK_IO_FLAG_ABORTED;
1420                                 __ublk_fail_req(ubq, io, rq);
1421                         }
1422                 }
1423         }
1424 }
1425
1426 static bool ublk_abort_requests(struct ublk_device *ub, struct ublk_queue *ubq)
1427 {
1428         struct gendisk *disk;
1429
1430         spin_lock(&ubq->cancel_lock);
1431         if (ubq->canceling) {
1432                 spin_unlock(&ubq->cancel_lock);
1433                 return false;
1434         }
1435         ubq->canceling = true;
1436         spin_unlock(&ubq->cancel_lock);
1437
1438         spin_lock(&ub->lock);
1439         disk = ub->ub_disk;
1440         if (disk)
1441                 get_device(disk_to_dev(disk));
1442         spin_unlock(&ub->lock);
1443
1444         /* Our disk has been dead */
1445         if (!disk)
1446                 return false;
1447
1448         /* Now we are serialized with ublk_queue_rq() */
1449         blk_mq_quiesce_queue(disk->queue);
1450         /* abort queue is for making forward progress */
1451         ublk_abort_queue(ub, ubq);
1452         blk_mq_unquiesce_queue(disk->queue);
1453         put_device(disk_to_dev(disk));
1454
1455         return true;
1456 }
1457
1458 static void ublk_cancel_cmd(struct ublk_queue *ubq, struct ublk_io *io,
1459                 unsigned int issue_flags)
1460 {
1461         bool done;
1462
1463         if (!(io->flags & UBLK_IO_FLAG_ACTIVE))
1464                 return;
1465
1466         spin_lock(&ubq->cancel_lock);
1467         done = !!(io->flags & UBLK_IO_FLAG_CANCELED);
1468         if (!done)
1469                 io->flags |= UBLK_IO_FLAG_CANCELED;
1470         spin_unlock(&ubq->cancel_lock);
1471
1472         if (!done)
1473                 io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0, issue_flags);
1474 }
1475
1476 /*
1477  * The ublk char device won't be closed when calling cancel fn, so both
1478  * ublk device and queue are guaranteed to be live
1479  */
1480 static void ublk_uring_cmd_cancel_fn(struct io_uring_cmd *cmd,
1481                 unsigned int issue_flags)
1482 {
1483         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
1484         struct ublk_queue *ubq = pdu->ubq;
1485         struct task_struct *task;
1486         struct ublk_device *ub;
1487         bool need_schedule;
1488         struct ublk_io *io;
1489
1490         if (WARN_ON_ONCE(!ubq))
1491                 return;
1492
1493         if (WARN_ON_ONCE(pdu->tag >= ubq->q_depth))
1494                 return;
1495
1496         task = io_uring_cmd_get_task(cmd);
1497         if (WARN_ON_ONCE(task && task != ubq->ubq_daemon))
1498                 return;
1499
1500         ub = ubq->dev;
1501         need_schedule = ublk_abort_requests(ub, ubq);
1502
1503         io = &ubq->ios[pdu->tag];
1504         WARN_ON_ONCE(io->cmd != cmd);
1505         ublk_cancel_cmd(ubq, io, issue_flags);
1506
1507         if (need_schedule) {
1508                 if (ublk_can_use_recovery(ub))
1509                         schedule_work(&ub->quiesce_work);
1510                 else
1511                         schedule_work(&ub->stop_work);
1512         }
1513 }
1514
1515 static inline bool ublk_queue_ready(struct ublk_queue *ubq)
1516 {
1517         return ubq->nr_io_ready == ubq->q_depth;
1518 }
1519
1520 static void ublk_cancel_queue(struct ublk_queue *ubq)
1521 {
1522         int i;
1523
1524         for (i = 0; i < ubq->q_depth; i++)
1525                 ublk_cancel_cmd(ubq, &ubq->ios[i], IO_URING_F_UNLOCKED);
1526 }
1527
1528 /* Cancel all pending commands, must be called after del_gendisk() returns */
1529 static void ublk_cancel_dev(struct ublk_device *ub)
1530 {
1531         int i;
1532
1533         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1534                 ublk_cancel_queue(ublk_get_queue(ub, i));
1535 }
1536
1537 static bool ublk_check_inflight_rq(struct request *rq, void *data)
1538 {
1539         bool *idle = data;
1540
1541         if (blk_mq_request_started(rq)) {
1542                 *idle = false;
1543                 return false;
1544         }
1545         return true;
1546 }
1547
1548 static void ublk_wait_tagset_rqs_idle(struct ublk_device *ub)
1549 {
1550         bool idle;
1551
1552         WARN_ON_ONCE(!blk_queue_quiesced(ub->ub_disk->queue));
1553         while (true) {
1554                 idle = true;
1555                 blk_mq_tagset_busy_iter(&ub->tag_set,
1556                                 ublk_check_inflight_rq, &idle);
1557                 if (idle)
1558                         break;
1559                 msleep(UBLK_REQUEUE_DELAY_MS);
1560         }
1561 }
1562
1563 static void __ublk_quiesce_dev(struct ublk_device *ub)
1564 {
1565         pr_devel("%s: quiesce ub: dev_id %d state %s\n",
1566                         __func__, ub->dev_info.dev_id,
1567                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1568                         "LIVE" : "QUIESCED");
1569         blk_mq_quiesce_queue(ub->ub_disk->queue);
1570         ublk_wait_tagset_rqs_idle(ub);
1571         ub->dev_info.state = UBLK_S_DEV_QUIESCED;
1572 }
1573
1574 static void ublk_quiesce_work_fn(struct work_struct *work)
1575 {
1576         struct ublk_device *ub =
1577                 container_of(work, struct ublk_device, quiesce_work);
1578
1579         mutex_lock(&ub->mutex);
1580         if (ub->dev_info.state != UBLK_S_DEV_LIVE)
1581                 goto unlock;
1582         __ublk_quiesce_dev(ub);
1583  unlock:
1584         mutex_unlock(&ub->mutex);
1585         ublk_cancel_dev(ub);
1586 }
1587
1588 static void ublk_unquiesce_dev(struct ublk_device *ub)
1589 {
1590         int i;
1591
1592         pr_devel("%s: unquiesce ub: dev_id %d state %s\n",
1593                         __func__, ub->dev_info.dev_id,
1594                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1595                         "LIVE" : "QUIESCED");
1596         /* quiesce_work has run. We let requeued rqs be aborted
1597          * before running fallback_wq. "force_abort" must be seen
1598          * after request queue is unqiuesced. Then del_gendisk()
1599          * can move on.
1600          */
1601         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1602                 ublk_get_queue(ub, i)->force_abort = true;
1603
1604         blk_mq_unquiesce_queue(ub->ub_disk->queue);
1605         /* We may have requeued some rqs in ublk_quiesce_queue() */
1606         blk_mq_kick_requeue_list(ub->ub_disk->queue);
1607 }
1608
1609 static void ublk_stop_dev(struct ublk_device *ub)
1610 {
1611         struct gendisk *disk;
1612
1613         mutex_lock(&ub->mutex);
1614         if (ub->dev_info.state == UBLK_S_DEV_DEAD)
1615                 goto unlock;
1616         if (ublk_can_use_recovery(ub)) {
1617                 if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1618                         __ublk_quiesce_dev(ub);
1619                 ublk_unquiesce_dev(ub);
1620         }
1621         del_gendisk(ub->ub_disk);
1622
1623         /* Sync with ublk_abort_queue() by holding the lock */
1624         spin_lock(&ub->lock);
1625         disk = ub->ub_disk;
1626         ub->dev_info.state = UBLK_S_DEV_DEAD;
1627         ub->dev_info.ublksrv_pid = -1;
1628         ub->ub_disk = NULL;
1629         spin_unlock(&ub->lock);
1630         put_disk(disk);
1631  unlock:
1632         mutex_unlock(&ub->mutex);
1633         ublk_cancel_dev(ub);
1634 }
1635
1636 /* device can only be started after all IOs are ready */
1637 static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
1638 {
1639         mutex_lock(&ub->mutex);
1640         ubq->nr_io_ready++;
1641         if (ublk_queue_ready(ubq)) {
1642                 ubq->ubq_daemon = current;
1643                 get_task_struct(ubq->ubq_daemon);
1644                 ub->nr_queues_ready++;
1645
1646                 if (capable(CAP_SYS_ADMIN))
1647                         ub->nr_privileged_daemon++;
1648         }
1649         if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
1650                 complete_all(&ub->completion);
1651         mutex_unlock(&ub->mutex);
1652 }
1653
1654 static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,
1655                 int tag)
1656 {
1657         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1658         struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag);
1659
1660         ublk_queue_cmd(ubq, req);
1661 }
1662
1663 static inline int ublk_check_cmd_op(u32 cmd_op)
1664 {
1665         u32 ioc_type = _IOC_TYPE(cmd_op);
1666
1667         if (!IS_ENABLED(CONFIG_BLKDEV_UBLK_LEGACY_OPCODES) && ioc_type != 'u')
1668                 return -EOPNOTSUPP;
1669
1670         if (ioc_type != 'u' && ioc_type != 0)
1671                 return -EOPNOTSUPP;
1672
1673         return 0;
1674 }
1675
1676 static inline void ublk_fill_io_cmd(struct ublk_io *io,
1677                 struct io_uring_cmd *cmd, unsigned long buf_addr)
1678 {
1679         io->cmd = cmd;
1680         io->flags |= UBLK_IO_FLAG_ACTIVE;
1681         io->addr = buf_addr;
1682 }
1683
1684 static inline void ublk_prep_cancel(struct io_uring_cmd *cmd,
1685                                     unsigned int issue_flags,
1686                                     struct ublk_queue *ubq, unsigned int tag)
1687 {
1688         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
1689
1690         /*
1691          * Safe to refer to @ubq since ublk_queue won't be died until its
1692          * commands are completed
1693          */
1694         pdu->ubq = ubq;
1695         pdu->tag = tag;
1696         io_uring_cmd_mark_cancelable(cmd, issue_flags);
1697 }
1698
1699 static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
1700                                unsigned int issue_flags,
1701                                const struct ublksrv_io_cmd *ub_cmd)
1702 {
1703         struct ublk_device *ub = cmd->file->private_data;
1704         struct ublk_queue *ubq;
1705         struct ublk_io *io;
1706         u32 cmd_op = cmd->cmd_op;
1707         unsigned tag = ub_cmd->tag;
1708         int ret = -EINVAL;
1709         struct request *req;
1710
1711         pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
1712                         __func__, cmd->cmd_op, ub_cmd->q_id, tag,
1713                         ub_cmd->result);
1714
1715         if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues)
1716                 goto out;
1717
1718         ubq = ublk_get_queue(ub, ub_cmd->q_id);
1719         if (!ubq || ub_cmd->q_id != ubq->q_id)
1720                 goto out;
1721
1722         if (ubq->ubq_daemon && ubq->ubq_daemon != current)
1723                 goto out;
1724
1725         if (tag >= ubq->q_depth)
1726                 goto out;
1727
1728         io = &ubq->ios[tag];
1729
1730         /* there is pending io cmd, something must be wrong */
1731         if (io->flags & UBLK_IO_FLAG_ACTIVE) {
1732                 ret = -EBUSY;
1733                 goto out;
1734         }
1735
1736         /*
1737          * ensure that the user issues UBLK_IO_NEED_GET_DATA
1738          * iff the driver have set the UBLK_IO_FLAG_NEED_GET_DATA.
1739          */
1740         if ((!!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA))
1741                         ^ (_IOC_NR(cmd_op) == UBLK_IO_NEED_GET_DATA))
1742                 goto out;
1743
1744         ret = ublk_check_cmd_op(cmd_op);
1745         if (ret)
1746                 goto out;
1747
1748         ret = -EINVAL;
1749         switch (_IOC_NR(cmd_op)) {
1750         case UBLK_IO_FETCH_REQ:
1751                 /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
1752                 if (ublk_queue_ready(ubq)) {
1753                         ret = -EBUSY;
1754                         goto out;
1755                 }
1756                 /*
1757                  * The io is being handled by server, so COMMIT_RQ is expected
1758                  * instead of FETCH_REQ
1759                  */
1760                 if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
1761                         goto out;
1762
1763                 if (!ublk_support_user_copy(ubq)) {
1764                         /*
1765                          * FETCH_RQ has to provide IO buffer if NEED GET
1766                          * DATA is not enabled
1767                          */
1768                         if (!ub_cmd->addr && !ublk_need_get_data(ubq))
1769                                 goto out;
1770                 } else if (ub_cmd->addr) {
1771                         /* User copy requires addr to be unset */
1772                         ret = -EINVAL;
1773                         goto out;
1774                 }
1775
1776                 ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
1777                 ublk_mark_io_ready(ub, ubq);
1778                 break;
1779         case UBLK_IO_COMMIT_AND_FETCH_REQ:
1780                 req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag);
1781
1782                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1783                         goto out;
1784
1785                 if (!ublk_support_user_copy(ubq)) {
1786                         /*
1787                          * COMMIT_AND_FETCH_REQ has to provide IO buffer if
1788                          * NEED GET DATA is not enabled or it is Read IO.
1789                          */
1790                         if (!ub_cmd->addr && (!ublk_need_get_data(ubq) ||
1791                                                 req_op(req) == REQ_OP_READ))
1792                                 goto out;
1793                 } else if (req_op(req) != REQ_OP_ZONE_APPEND && ub_cmd->addr) {
1794                         /*
1795                          * User copy requires addr to be unset when command is
1796                          * not zone append
1797                          */
1798                         ret = -EINVAL;
1799                         goto out;
1800                 }
1801
1802                 ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
1803                 ublk_commit_completion(ub, ub_cmd);
1804                 break;
1805         case UBLK_IO_NEED_GET_DATA:
1806                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1807                         goto out;
1808                 ublk_fill_io_cmd(io, cmd, ub_cmd->addr);
1809                 ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag);
1810                 break;
1811         default:
1812                 goto out;
1813         }
1814         ublk_prep_cancel(cmd, issue_flags, ubq, tag);
1815         return -EIOCBQUEUED;
1816
1817  out:
1818         io_uring_cmd_done(cmd, ret, 0, issue_flags);
1819         pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n",
1820                         __func__, cmd_op, tag, ret, io->flags);
1821         return -EIOCBQUEUED;
1822 }
1823
1824 static inline struct request *__ublk_check_and_get_req(struct ublk_device *ub,
1825                 struct ublk_queue *ubq, int tag, size_t offset)
1826 {
1827         struct request *req;
1828
1829         if (!ublk_need_req_ref(ubq))
1830                 return NULL;
1831
1832         req = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], tag);
1833         if (!req)
1834                 return NULL;
1835
1836         if (!ublk_get_req_ref(ubq, req))
1837                 return NULL;
1838
1839         if (unlikely(!blk_mq_request_started(req) || req->tag != tag))
1840                 goto fail_put;
1841
1842         if (!ublk_rq_has_data(req))
1843                 goto fail_put;
1844
1845         if (offset > blk_rq_bytes(req))
1846                 goto fail_put;
1847
1848         return req;
1849 fail_put:
1850         ublk_put_req_ref(ubq, req);
1851         return NULL;
1852 }
1853
1854 static inline int ublk_ch_uring_cmd_local(struct io_uring_cmd *cmd,
1855                 unsigned int issue_flags)
1856 {
1857         /*
1858          * Not necessary for async retry, but let's keep it simple and always
1859          * copy the values to avoid any potential reuse.
1860          */
1861         const struct ublksrv_io_cmd *ub_src = io_uring_sqe_cmd(cmd->sqe);
1862         const struct ublksrv_io_cmd ub_cmd = {
1863                 .q_id = READ_ONCE(ub_src->q_id),
1864                 .tag = READ_ONCE(ub_src->tag),
1865                 .result = READ_ONCE(ub_src->result),
1866                 .addr = READ_ONCE(ub_src->addr)
1867         };
1868
1869         WARN_ON_ONCE(issue_flags & IO_URING_F_UNLOCKED);
1870
1871         return __ublk_ch_uring_cmd(cmd, issue_flags, &ub_cmd);
1872 }
1873
1874 static void ublk_ch_uring_cmd_cb(struct io_uring_cmd *cmd,
1875                 unsigned int issue_flags)
1876 {
1877         ublk_ch_uring_cmd_local(cmd, issue_flags);
1878 }
1879
1880 static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
1881 {
1882         if (unlikely(issue_flags & IO_URING_F_CANCEL)) {
1883                 ublk_uring_cmd_cancel_fn(cmd, issue_flags);
1884                 return 0;
1885         }
1886
1887         /* well-implemented server won't run into unlocked */
1888         if (unlikely(issue_flags & IO_URING_F_UNLOCKED)) {
1889                 io_uring_cmd_complete_in_task(cmd, ublk_ch_uring_cmd_cb);
1890                 return -EIOCBQUEUED;
1891         }
1892
1893         return ublk_ch_uring_cmd_local(cmd, issue_flags);
1894 }
1895
1896 static inline bool ublk_check_ubuf_dir(const struct request *req,
1897                 int ubuf_dir)
1898 {
1899         /* copy ubuf to request pages */
1900         if ((req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_DRV_IN) &&
1901             ubuf_dir == ITER_SOURCE)
1902                 return true;
1903
1904         /* copy request pages to ubuf */
1905         if ((req_op(req) == REQ_OP_WRITE ||
1906              req_op(req) == REQ_OP_ZONE_APPEND) &&
1907             ubuf_dir == ITER_DEST)
1908                 return true;
1909
1910         return false;
1911 }
1912
1913 static struct request *ublk_check_and_get_req(struct kiocb *iocb,
1914                 struct iov_iter *iter, size_t *off, int dir)
1915 {
1916         struct ublk_device *ub = iocb->ki_filp->private_data;
1917         struct ublk_queue *ubq;
1918         struct request *req;
1919         size_t buf_off;
1920         u16 tag, q_id;
1921
1922         if (!ub)
1923                 return ERR_PTR(-EACCES);
1924
1925         if (!user_backed_iter(iter))
1926                 return ERR_PTR(-EACCES);
1927
1928         if (ub->dev_info.state == UBLK_S_DEV_DEAD)
1929                 return ERR_PTR(-EACCES);
1930
1931         tag = ublk_pos_to_tag(iocb->ki_pos);
1932         q_id = ublk_pos_to_hwq(iocb->ki_pos);
1933         buf_off = ublk_pos_to_buf_off(iocb->ki_pos);
1934
1935         if (q_id >= ub->dev_info.nr_hw_queues)
1936                 return ERR_PTR(-EINVAL);
1937
1938         ubq = ublk_get_queue(ub, q_id);
1939         if (!ubq)
1940                 return ERR_PTR(-EINVAL);
1941
1942         if (tag >= ubq->q_depth)
1943                 return ERR_PTR(-EINVAL);
1944
1945         req = __ublk_check_and_get_req(ub, ubq, tag, buf_off);
1946         if (!req)
1947                 return ERR_PTR(-EINVAL);
1948
1949         if (!req->mq_hctx || !req->mq_hctx->driver_data)
1950                 goto fail;
1951
1952         if (!ublk_check_ubuf_dir(req, dir))
1953                 goto fail;
1954
1955         *off = buf_off;
1956         return req;
1957 fail:
1958         ublk_put_req_ref(ubq, req);
1959         return ERR_PTR(-EACCES);
1960 }
1961
1962 static ssize_t ublk_ch_read_iter(struct kiocb *iocb, struct iov_iter *to)
1963 {
1964         struct ublk_queue *ubq;
1965         struct request *req;
1966         size_t buf_off;
1967         size_t ret;
1968
1969         req = ublk_check_and_get_req(iocb, to, &buf_off, ITER_DEST);
1970         if (IS_ERR(req))
1971                 return PTR_ERR(req);
1972
1973         ret = ublk_copy_user_pages(req, buf_off, to, ITER_DEST);
1974         ubq = req->mq_hctx->driver_data;
1975         ublk_put_req_ref(ubq, req);
1976
1977         return ret;
1978 }
1979
1980 static ssize_t ublk_ch_write_iter(struct kiocb *iocb, struct iov_iter *from)
1981 {
1982         struct ublk_queue *ubq;
1983         struct request *req;
1984         size_t buf_off;
1985         size_t ret;
1986
1987         req = ublk_check_and_get_req(iocb, from, &buf_off, ITER_SOURCE);
1988         if (IS_ERR(req))
1989                 return PTR_ERR(req);
1990
1991         ret = ublk_copy_user_pages(req, buf_off, from, ITER_SOURCE);
1992         ubq = req->mq_hctx->driver_data;
1993         ublk_put_req_ref(ubq, req);
1994
1995         return ret;
1996 }
1997
1998 static const struct file_operations ublk_ch_fops = {
1999         .owner = THIS_MODULE,
2000         .open = ublk_ch_open,
2001         .release = ublk_ch_release,
2002         .llseek = no_llseek,
2003         .read_iter = ublk_ch_read_iter,
2004         .write_iter = ublk_ch_write_iter,
2005         .uring_cmd = ublk_ch_uring_cmd,
2006         .mmap = ublk_ch_mmap,
2007 };
2008
2009 static void ublk_deinit_queue(struct ublk_device *ub, int q_id)
2010 {
2011         int size = ublk_queue_cmd_buf_size(ub, q_id);
2012         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
2013
2014         if (ubq->ubq_daemon)
2015                 put_task_struct(ubq->ubq_daemon);
2016         if (ubq->io_cmd_buf)
2017                 free_pages((unsigned long)ubq->io_cmd_buf, get_order(size));
2018 }
2019
2020 static int ublk_init_queue(struct ublk_device *ub, int q_id)
2021 {
2022         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
2023         gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO;
2024         void *ptr;
2025         int size;
2026
2027         spin_lock_init(&ubq->cancel_lock);
2028         ubq->flags = ub->dev_info.flags;
2029         ubq->q_id = q_id;
2030         ubq->q_depth = ub->dev_info.queue_depth;
2031         size = ublk_queue_cmd_buf_size(ub, q_id);
2032
2033         ptr = (void *) __get_free_pages(gfp_flags, get_order(size));
2034         if (!ptr)
2035                 return -ENOMEM;
2036
2037         ubq->io_cmd_buf = ptr;
2038         ubq->dev = ub;
2039         return 0;
2040 }
2041
2042 static void ublk_deinit_queues(struct ublk_device *ub)
2043 {
2044         int nr_queues = ub->dev_info.nr_hw_queues;
2045         int i;
2046
2047         if (!ub->__queues)
2048                 return;
2049
2050         for (i = 0; i < nr_queues; i++)
2051                 ublk_deinit_queue(ub, i);
2052         kfree(ub->__queues);
2053 }
2054
2055 static int ublk_init_queues(struct ublk_device *ub)
2056 {
2057         int nr_queues = ub->dev_info.nr_hw_queues;
2058         int depth = ub->dev_info.queue_depth;
2059         int ubq_size = sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io);
2060         int i, ret = -ENOMEM;
2061
2062         ub->queue_size = ubq_size;
2063         ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL);
2064         if (!ub->__queues)
2065                 return ret;
2066
2067         for (i = 0; i < nr_queues; i++) {
2068                 if (ublk_init_queue(ub, i))
2069                         goto fail;
2070         }
2071
2072         init_completion(&ub->completion);
2073         return 0;
2074
2075  fail:
2076         ublk_deinit_queues(ub);
2077         return ret;
2078 }
2079
2080 static int ublk_alloc_dev_number(struct ublk_device *ub, int idx)
2081 {
2082         int i = idx;
2083         int err;
2084
2085         spin_lock(&ublk_idr_lock);
2086         /* allocate id, if @id >= 0, we're requesting that specific id */
2087         if (i >= 0) {
2088                 err = idr_alloc(&ublk_index_idr, ub, i, i + 1, GFP_NOWAIT);
2089                 if (err == -ENOSPC)
2090                         err = -EEXIST;
2091         } else {
2092                 err = idr_alloc(&ublk_index_idr, ub, 0, UBLK_MAX_UBLKS,
2093                                 GFP_NOWAIT);
2094         }
2095         spin_unlock(&ublk_idr_lock);
2096
2097         if (err >= 0)
2098                 ub->ub_number = err;
2099
2100         return err;
2101 }
2102
2103 static void ublk_free_dev_number(struct ublk_device *ub)
2104 {
2105         spin_lock(&ublk_idr_lock);
2106         idr_remove(&ublk_index_idr, ub->ub_number);
2107         wake_up_all(&ublk_idr_wq);
2108         spin_unlock(&ublk_idr_lock);
2109 }
2110
2111 static void ublk_cdev_rel(struct device *dev)
2112 {
2113         struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev);
2114
2115         blk_mq_free_tag_set(&ub->tag_set);
2116         ublk_deinit_queues(ub);
2117         ublk_free_dev_number(ub);
2118         mutex_destroy(&ub->mutex);
2119         kfree(ub);
2120 }
2121
2122 static int ublk_add_chdev(struct ublk_device *ub)
2123 {
2124         struct device *dev = &ub->cdev_dev;
2125         int minor = ub->ub_number;
2126         int ret;
2127
2128         dev->parent = ublk_misc.this_device;
2129         dev->devt = MKDEV(MAJOR(ublk_chr_devt), minor);
2130         dev->class = &ublk_chr_class;
2131         dev->release = ublk_cdev_rel;
2132         device_initialize(dev);
2133
2134         ret = dev_set_name(dev, "ublkc%d", minor);
2135         if (ret)
2136                 goto fail;
2137
2138         cdev_init(&ub->cdev, &ublk_ch_fops);
2139         ret = cdev_device_add(&ub->cdev, dev);
2140         if (ret)
2141                 goto fail;
2142
2143         ublks_added++;
2144         return 0;
2145  fail:
2146         put_device(dev);
2147         return ret;
2148 }
2149
2150 static void ublk_stop_work_fn(struct work_struct *work)
2151 {
2152         struct ublk_device *ub =
2153                 container_of(work, struct ublk_device, stop_work);
2154
2155         ublk_stop_dev(ub);
2156 }
2157
2158 /* align max io buffer size with PAGE_SIZE */
2159 static void ublk_align_max_io_size(struct ublk_device *ub)
2160 {
2161         unsigned int max_io_bytes = ub->dev_info.max_io_buf_bytes;
2162
2163         ub->dev_info.max_io_buf_bytes =
2164                 round_down(max_io_bytes, PAGE_SIZE);
2165 }
2166
2167 static int ublk_add_tag_set(struct ublk_device *ub)
2168 {
2169         ub->tag_set.ops = &ublk_mq_ops;
2170         ub->tag_set.nr_hw_queues = ub->dev_info.nr_hw_queues;
2171         ub->tag_set.queue_depth = ub->dev_info.queue_depth;
2172         ub->tag_set.numa_node = NUMA_NO_NODE;
2173         ub->tag_set.cmd_size = sizeof(struct ublk_rq_data);
2174         ub->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
2175         ub->tag_set.driver_data = ub;
2176         return blk_mq_alloc_tag_set(&ub->tag_set);
2177 }
2178
2179 static void ublk_remove(struct ublk_device *ub)
2180 {
2181         ublk_stop_dev(ub);
2182         cancel_work_sync(&ub->stop_work);
2183         cancel_work_sync(&ub->quiesce_work);
2184         cdev_device_del(&ub->cdev, &ub->cdev_dev);
2185         put_device(&ub->cdev_dev);
2186         ublks_added--;
2187 }
2188
2189 static struct ublk_device *ublk_get_device_from_id(int idx)
2190 {
2191         struct ublk_device *ub = NULL;
2192
2193         if (idx < 0)
2194                 return NULL;
2195
2196         spin_lock(&ublk_idr_lock);
2197         ub = idr_find(&ublk_index_idr, idx);
2198         if (ub)
2199                 ub = ublk_get_device(ub);
2200         spin_unlock(&ublk_idr_lock);
2201
2202         return ub;
2203 }
2204
2205 static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
2206 {
2207         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2208         int ublksrv_pid = (int)header->data[0];
2209         struct gendisk *disk;
2210         int ret = -EINVAL;
2211
2212         if (ublksrv_pid <= 0)
2213                 return -EINVAL;
2214
2215         if (wait_for_completion_interruptible(&ub->completion) != 0)
2216                 return -EINTR;
2217
2218         mutex_lock(&ub->mutex);
2219         if (ub->dev_info.state == UBLK_S_DEV_LIVE ||
2220             test_bit(UB_STATE_USED, &ub->state)) {
2221                 ret = -EEXIST;
2222                 goto out_unlock;
2223         }
2224
2225         disk = blk_mq_alloc_disk(&ub->tag_set, NULL);
2226         if (IS_ERR(disk)) {
2227                 ret = PTR_ERR(disk);
2228                 goto out_unlock;
2229         }
2230         sprintf(disk->disk_name, "ublkb%d", ub->ub_number);
2231         disk->fops = &ub_fops;
2232         disk->private_data = ub;
2233
2234         ub->dev_info.ublksrv_pid = ublksrv_pid;
2235         ub->ub_disk = disk;
2236
2237         ret = ublk_apply_params(ub);
2238         if (ret)
2239                 goto out_put_disk;
2240
2241         /* don't probe partitions if any one ubq daemon is un-trusted */
2242         if (ub->nr_privileged_daemon != ub->nr_queues_ready)
2243                 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
2244
2245         get_device(&ub->cdev_dev);
2246         ub->dev_info.state = UBLK_S_DEV_LIVE;
2247
2248         if (ublk_dev_is_zoned(ub)) {
2249                 ret = ublk_revalidate_disk_zones(ub);
2250                 if (ret)
2251                         goto out_put_cdev;
2252         }
2253
2254         ret = add_disk(disk);
2255         if (ret)
2256                 goto out_put_cdev;
2257
2258         set_bit(UB_STATE_USED, &ub->state);
2259
2260 out_put_cdev:
2261         if (ret) {
2262                 ub->dev_info.state = UBLK_S_DEV_DEAD;
2263                 ublk_put_device(ub);
2264         }
2265 out_put_disk:
2266         if (ret)
2267                 put_disk(disk);
2268 out_unlock:
2269         mutex_unlock(&ub->mutex);
2270         return ret;
2271 }
2272
2273 static int ublk_ctrl_get_queue_affinity(struct ublk_device *ub,
2274                 struct io_uring_cmd *cmd)
2275 {
2276         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2277         void __user *argp = (void __user *)(unsigned long)header->addr;
2278         cpumask_var_t cpumask;
2279         unsigned long queue;
2280         unsigned int retlen;
2281         unsigned int i;
2282         int ret;
2283
2284         if (header->len * BITS_PER_BYTE < nr_cpu_ids)
2285                 return -EINVAL;
2286         if (header->len & (sizeof(unsigned long)-1))
2287                 return -EINVAL;
2288         if (!header->addr)
2289                 return -EINVAL;
2290
2291         queue = header->data[0];
2292         if (queue >= ub->dev_info.nr_hw_queues)
2293                 return -EINVAL;
2294
2295         if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
2296                 return -ENOMEM;
2297
2298         for_each_possible_cpu(i) {
2299                 if (ub->tag_set.map[HCTX_TYPE_DEFAULT].mq_map[i] == queue)
2300                         cpumask_set_cpu(i, cpumask);
2301         }
2302
2303         ret = -EFAULT;
2304         retlen = min_t(unsigned short, header->len, cpumask_size());
2305         if (copy_to_user(argp, cpumask, retlen))
2306                 goto out_free_cpumask;
2307         if (retlen != header->len &&
2308             clear_user(argp + retlen, header->len - retlen))
2309                 goto out_free_cpumask;
2310
2311         ret = 0;
2312 out_free_cpumask:
2313         free_cpumask_var(cpumask);
2314         return ret;
2315 }
2316
2317 static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info)
2318 {
2319         pr_devel("%s: dev id %d flags %llx\n", __func__,
2320                         info->dev_id, info->flags);
2321         pr_devel("\t nr_hw_queues %d queue_depth %d\n",
2322                         info->nr_hw_queues, info->queue_depth);
2323 }
2324
2325 static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
2326 {
2327         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2328         void __user *argp = (void __user *)(unsigned long)header->addr;
2329         struct ublksrv_ctrl_dev_info info;
2330         struct ublk_device *ub;
2331         int ret = -EINVAL;
2332
2333         if (header->len < sizeof(info) || !header->addr)
2334                 return -EINVAL;
2335         if (header->queue_id != (u16)-1) {
2336                 pr_warn("%s: queue_id is wrong %x\n",
2337                         __func__, header->queue_id);
2338                 return -EINVAL;
2339         }
2340
2341         if (copy_from_user(&info, argp, sizeof(info)))
2342                 return -EFAULT;
2343
2344         if (capable(CAP_SYS_ADMIN))
2345                 info.flags &= ~UBLK_F_UNPRIVILEGED_DEV;
2346         else if (!(info.flags & UBLK_F_UNPRIVILEGED_DEV))
2347                 return -EPERM;
2348
2349         /*
2350          * unprivileged device can't be trusted, but RECOVERY and
2351          * RECOVERY_REISSUE still may hang error handling, so can't
2352          * support recovery features for unprivileged ublk now
2353          *
2354          * TODO: provide forward progress for RECOVERY handler, so that
2355          * unprivileged device can benefit from it
2356          */
2357         if (info.flags & UBLK_F_UNPRIVILEGED_DEV)
2358                 info.flags &= ~(UBLK_F_USER_RECOVERY_REISSUE |
2359                                 UBLK_F_USER_RECOVERY);
2360
2361         /* the created device is always owned by current user */
2362         ublk_store_owner_uid_gid(&info.owner_uid, &info.owner_gid);
2363
2364         if (header->dev_id != info.dev_id) {
2365                 pr_warn("%s: dev id not match %u %u\n",
2366                         __func__, header->dev_id, info.dev_id);
2367                 return -EINVAL;
2368         }
2369
2370         if (header->dev_id != U32_MAX && header->dev_id >= UBLK_MAX_UBLKS) {
2371                 pr_warn("%s: dev id is too large. Max supported is %d\n",
2372                         __func__, UBLK_MAX_UBLKS - 1);
2373                 return -EINVAL;
2374         }
2375
2376         ublk_dump_dev_info(&info);
2377
2378         ret = mutex_lock_killable(&ublk_ctl_mutex);
2379         if (ret)
2380                 return ret;
2381
2382         ret = -EACCES;
2383         if (ublks_added >= ublks_max)
2384                 goto out_unlock;
2385
2386         ret = -ENOMEM;
2387         ub = kzalloc(sizeof(*ub), GFP_KERNEL);
2388         if (!ub)
2389                 goto out_unlock;
2390         mutex_init(&ub->mutex);
2391         spin_lock_init(&ub->lock);
2392         INIT_WORK(&ub->quiesce_work, ublk_quiesce_work_fn);
2393         INIT_WORK(&ub->stop_work, ublk_stop_work_fn);
2394
2395         ret = ublk_alloc_dev_number(ub, header->dev_id);
2396         if (ret < 0)
2397                 goto out_free_ub;
2398
2399         memcpy(&ub->dev_info, &info, sizeof(info));
2400
2401         /* update device id */
2402         ub->dev_info.dev_id = ub->ub_number;
2403
2404         /*
2405          * 64bit flags will be copied back to userspace as feature
2406          * negotiation result, so have to clear flags which driver
2407          * doesn't support yet, then userspace can get correct flags
2408          * (features) to handle.
2409          */
2410         ub->dev_info.flags &= UBLK_F_ALL;
2411
2412         ub->dev_info.flags |= UBLK_F_CMD_IOCTL_ENCODE |
2413                 UBLK_F_URING_CMD_COMP_IN_TASK;
2414
2415         /* GET_DATA isn't needed any more with USER_COPY */
2416         if (ublk_dev_is_user_copy(ub))
2417                 ub->dev_info.flags &= ~UBLK_F_NEED_GET_DATA;
2418
2419         /* Zoned storage support requires user copy feature */
2420         if (ublk_dev_is_zoned(ub) &&
2421             (!IS_ENABLED(CONFIG_BLK_DEV_ZONED) || !ublk_dev_is_user_copy(ub))) {
2422                 ret = -EINVAL;
2423                 goto out_free_dev_number;
2424         }
2425
2426         /* We are not ready to support zero copy */
2427         ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
2428
2429         ub->dev_info.nr_hw_queues = min_t(unsigned int,
2430                         ub->dev_info.nr_hw_queues, nr_cpu_ids);
2431         ublk_align_max_io_size(ub);
2432
2433         ret = ublk_init_queues(ub);
2434         if (ret)
2435                 goto out_free_dev_number;
2436
2437         ret = ublk_add_tag_set(ub);
2438         if (ret)
2439                 goto out_deinit_queues;
2440
2441         ret = -EFAULT;
2442         if (copy_to_user(argp, &ub->dev_info, sizeof(info)))
2443                 goto out_free_tag_set;
2444
2445         /*
2446          * Add the char dev so that ublksrv daemon can be setup.
2447          * ublk_add_chdev() will cleanup everything if it fails.
2448          */
2449         ret = ublk_add_chdev(ub);
2450         goto out_unlock;
2451
2452 out_free_tag_set:
2453         blk_mq_free_tag_set(&ub->tag_set);
2454 out_deinit_queues:
2455         ublk_deinit_queues(ub);
2456 out_free_dev_number:
2457         ublk_free_dev_number(ub);
2458 out_free_ub:
2459         mutex_destroy(&ub->mutex);
2460         kfree(ub);
2461 out_unlock:
2462         mutex_unlock(&ublk_ctl_mutex);
2463         return ret;
2464 }
2465
2466 static inline bool ublk_idr_freed(int id)
2467 {
2468         void *ptr;
2469
2470         spin_lock(&ublk_idr_lock);
2471         ptr = idr_find(&ublk_index_idr, id);
2472         spin_unlock(&ublk_idr_lock);
2473
2474         return ptr == NULL;
2475 }
2476
2477 static int ublk_ctrl_del_dev(struct ublk_device **p_ub)
2478 {
2479         struct ublk_device *ub = *p_ub;
2480         int idx = ub->ub_number;
2481         int ret;
2482
2483         ret = mutex_lock_killable(&ublk_ctl_mutex);
2484         if (ret)
2485                 return ret;
2486
2487         if (!test_bit(UB_STATE_DELETED, &ub->state)) {
2488                 ublk_remove(ub);
2489                 set_bit(UB_STATE_DELETED, &ub->state);
2490         }
2491
2492         /* Mark the reference as consumed */
2493         *p_ub = NULL;
2494         ublk_put_device(ub);
2495         mutex_unlock(&ublk_ctl_mutex);
2496
2497         /*
2498          * Wait until the idr is removed, then it can be reused after
2499          * DEL_DEV command is returned.
2500          *
2501          * If we returns because of user interrupt, future delete command
2502          * may come:
2503          *
2504          * - the device number isn't freed, this device won't or needn't
2505          *   be deleted again, since UB_STATE_DELETED is set, and device
2506          *   will be released after the last reference is dropped
2507          *
2508          * - the device number is freed already, we will not find this
2509          *   device via ublk_get_device_from_id()
2510          */
2511         if (wait_event_interruptible(ublk_idr_wq, ublk_idr_freed(idx)))
2512                 return -EINTR;
2513         return 0;
2514 }
2515
2516 static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd)
2517 {
2518         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2519
2520         pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n",
2521                         __func__, cmd->cmd_op, header->dev_id, header->queue_id,
2522                         header->data[0], header->addr, header->len);
2523 }
2524
2525 static int ublk_ctrl_stop_dev(struct ublk_device *ub)
2526 {
2527         ublk_stop_dev(ub);
2528         cancel_work_sync(&ub->stop_work);
2529         cancel_work_sync(&ub->quiesce_work);
2530
2531         return 0;
2532 }
2533
2534 static int ublk_ctrl_get_dev_info(struct ublk_device *ub,
2535                 struct io_uring_cmd *cmd)
2536 {
2537         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2538         void __user *argp = (void __user *)(unsigned long)header->addr;
2539
2540         if (header->len < sizeof(struct ublksrv_ctrl_dev_info) || !header->addr)
2541                 return -EINVAL;
2542
2543         if (copy_to_user(argp, &ub->dev_info, sizeof(ub->dev_info)))
2544                 return -EFAULT;
2545
2546         return 0;
2547 }
2548
2549 /* TYPE_DEVT is readonly, so fill it up before returning to userspace */
2550 static void ublk_ctrl_fill_params_devt(struct ublk_device *ub)
2551 {
2552         ub->params.devt.char_major = MAJOR(ub->cdev_dev.devt);
2553         ub->params.devt.char_minor = MINOR(ub->cdev_dev.devt);
2554
2555         if (ub->ub_disk) {
2556                 ub->params.devt.disk_major = MAJOR(disk_devt(ub->ub_disk));
2557                 ub->params.devt.disk_minor = MINOR(disk_devt(ub->ub_disk));
2558         } else {
2559                 ub->params.devt.disk_major = 0;
2560                 ub->params.devt.disk_minor = 0;
2561         }
2562         ub->params.types |= UBLK_PARAM_TYPE_DEVT;
2563 }
2564
2565 static int ublk_ctrl_get_params(struct ublk_device *ub,
2566                 struct io_uring_cmd *cmd)
2567 {
2568         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2569         void __user *argp = (void __user *)(unsigned long)header->addr;
2570         struct ublk_params_header ph;
2571         int ret;
2572
2573         if (header->len <= sizeof(ph) || !header->addr)
2574                 return -EINVAL;
2575
2576         if (copy_from_user(&ph, argp, sizeof(ph)))
2577                 return -EFAULT;
2578
2579         if (ph.len > header->len || !ph.len)
2580                 return -EINVAL;
2581
2582         if (ph.len > sizeof(struct ublk_params))
2583                 ph.len = sizeof(struct ublk_params);
2584
2585         mutex_lock(&ub->mutex);
2586         ublk_ctrl_fill_params_devt(ub);
2587         if (copy_to_user(argp, &ub->params, ph.len))
2588                 ret = -EFAULT;
2589         else
2590                 ret = 0;
2591         mutex_unlock(&ub->mutex);
2592
2593         return ret;
2594 }
2595
2596 static int ublk_ctrl_set_params(struct ublk_device *ub,
2597                 struct io_uring_cmd *cmd)
2598 {
2599         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2600         void __user *argp = (void __user *)(unsigned long)header->addr;
2601         struct ublk_params_header ph;
2602         int ret = -EFAULT;
2603
2604         if (header->len <= sizeof(ph) || !header->addr)
2605                 return -EINVAL;
2606
2607         if (copy_from_user(&ph, argp, sizeof(ph)))
2608                 return -EFAULT;
2609
2610         if (ph.len > header->len || !ph.len || !ph.types)
2611                 return -EINVAL;
2612
2613         if (ph.len > sizeof(struct ublk_params))
2614                 ph.len = sizeof(struct ublk_params);
2615
2616         /* parameters can only be changed when device isn't live */
2617         mutex_lock(&ub->mutex);
2618         if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
2619                 ret = -EACCES;
2620         } else if (copy_from_user(&ub->params, argp, ph.len)) {
2621                 ret = -EFAULT;
2622         } else {
2623                 /* clear all we don't support yet */
2624                 ub->params.types &= UBLK_PARAM_TYPE_ALL;
2625                 ret = ublk_validate_params(ub);
2626                 if (ret)
2627                         ub->params.types = 0;
2628         }
2629         mutex_unlock(&ub->mutex);
2630
2631         return ret;
2632 }
2633
2634 static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
2635 {
2636         int i;
2637
2638         WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));
2639
2640         /* All old ioucmds have to be completed */
2641         ubq->nr_io_ready = 0;
2642         /* old daemon is PF_EXITING, put it now */
2643         put_task_struct(ubq->ubq_daemon);
2644         /* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */
2645         ubq->ubq_daemon = NULL;
2646         ubq->timeout = false;
2647         ubq->canceling = false;
2648
2649         for (i = 0; i < ubq->q_depth; i++) {
2650                 struct ublk_io *io = &ubq->ios[i];
2651
2652                 /* forget everything now and be ready for new FETCH_REQ */
2653                 io->flags = 0;
2654                 io->cmd = NULL;
2655                 io->addr = 0;
2656         }
2657 }
2658
2659 static int ublk_ctrl_start_recovery(struct ublk_device *ub,
2660                 struct io_uring_cmd *cmd)
2661 {
2662         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2663         int ret = -EINVAL;
2664         int i;
2665
2666         mutex_lock(&ub->mutex);
2667         if (!ublk_can_use_recovery(ub))
2668                 goto out_unlock;
2669         /*
2670          * START_RECOVERY is only allowd after:
2671          *
2672          * (1) UB_STATE_OPEN is not set, which means the dying process is exited
2673          *     and related io_uring ctx is freed so file struct of /dev/ublkcX is
2674          *     released.
2675          *
2676          * (2) UBLK_S_DEV_QUIESCED is set, which means the quiesce_work:
2677          *     (a)has quiesced request queue
2678          *     (b)has requeued every inflight rqs whose io_flags is ACTIVE
2679          *     (c)has requeued/aborted every inflight rqs whose io_flags is NOT ACTIVE
2680          *     (d)has completed/camceled all ioucmds owned by ther dying process
2681          */
2682         if (test_bit(UB_STATE_OPEN, &ub->state) ||
2683                         ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
2684                 ret = -EBUSY;
2685                 goto out_unlock;
2686         }
2687         pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id);
2688         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
2689                 ublk_queue_reinit(ub, ublk_get_queue(ub, i));
2690         /* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */
2691         ub->mm = NULL;
2692         ub->nr_queues_ready = 0;
2693         ub->nr_privileged_daemon = 0;
2694         init_completion(&ub->completion);
2695         ret = 0;
2696  out_unlock:
2697         mutex_unlock(&ub->mutex);
2698         return ret;
2699 }
2700
2701 static int ublk_ctrl_end_recovery(struct ublk_device *ub,
2702                 struct io_uring_cmd *cmd)
2703 {
2704         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2705         int ublksrv_pid = (int)header->data[0];
2706         int ret = -EINVAL;
2707
2708         pr_devel("%s: Waiting for new ubq_daemons(nr: %d) are ready, dev id %d...\n",
2709                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
2710         /* wait until new ubq_daemon sending all FETCH_REQ */
2711         if (wait_for_completion_interruptible(&ub->completion))
2712                 return -EINTR;
2713
2714         pr_devel("%s: All new ubq_daemons(nr: %d) are ready, dev id %d\n",
2715                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
2716
2717         mutex_lock(&ub->mutex);
2718         if (!ublk_can_use_recovery(ub))
2719                 goto out_unlock;
2720
2721         if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
2722                 ret = -EBUSY;
2723                 goto out_unlock;
2724         }
2725         ub->dev_info.ublksrv_pid = ublksrv_pid;
2726         pr_devel("%s: new ublksrv_pid %d, dev id %d\n",
2727                         __func__, ublksrv_pid, header->dev_id);
2728         blk_mq_unquiesce_queue(ub->ub_disk->queue);
2729         pr_devel("%s: queue unquiesced, dev id %d.\n",
2730                         __func__, header->dev_id);
2731         blk_mq_kick_requeue_list(ub->ub_disk->queue);
2732         ub->dev_info.state = UBLK_S_DEV_LIVE;
2733         ret = 0;
2734  out_unlock:
2735         mutex_unlock(&ub->mutex);
2736         return ret;
2737 }
2738
2739 static int ublk_ctrl_get_features(struct io_uring_cmd *cmd)
2740 {
2741         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2742         void __user *argp = (void __user *)(unsigned long)header->addr;
2743         u64 features = UBLK_F_ALL & ~UBLK_F_SUPPORT_ZERO_COPY;
2744
2745         if (header->len != UBLK_FEATURES_LEN || !header->addr)
2746                 return -EINVAL;
2747
2748         if (copy_to_user(argp, &features, UBLK_FEATURES_LEN))
2749                 return -EFAULT;
2750
2751         return 0;
2752 }
2753
2754 /*
2755  * All control commands are sent via /dev/ublk-control, so we have to check
2756  * the destination device's permission
2757  */
2758 static int ublk_char_dev_permission(struct ublk_device *ub,
2759                 const char *dev_path, int mask)
2760 {
2761         int err;
2762         struct path path;
2763         struct kstat stat;
2764
2765         err = kern_path(dev_path, LOOKUP_FOLLOW, &path);
2766         if (err)
2767                 return err;
2768
2769         err = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
2770         if (err)
2771                 goto exit;
2772
2773         err = -EPERM;
2774         if (stat.rdev != ub->cdev_dev.devt || !S_ISCHR(stat.mode))
2775                 goto exit;
2776
2777         err = inode_permission(&nop_mnt_idmap,
2778                         d_backing_inode(path.dentry), mask);
2779 exit:
2780         path_put(&path);
2781         return err;
2782 }
2783
2784 static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
2785                 struct io_uring_cmd *cmd)
2786 {
2787         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)io_uring_sqe_cmd(cmd->sqe);
2788         bool unprivileged = ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV;
2789         void __user *argp = (void __user *)(unsigned long)header->addr;
2790         char *dev_path = NULL;
2791         int ret = 0;
2792         int mask;
2793
2794         if (!unprivileged) {
2795                 if (!capable(CAP_SYS_ADMIN))
2796                         return -EPERM;
2797                 /*
2798                  * The new added command of UBLK_CMD_GET_DEV_INFO2 includes
2799                  * char_dev_path in payload too, since userspace may not
2800                  * know if the specified device is created as unprivileged
2801                  * mode.
2802                  */
2803                 if (_IOC_NR(cmd->cmd_op) != UBLK_CMD_GET_DEV_INFO2)
2804                         return 0;
2805         }
2806
2807         /*
2808          * User has to provide the char device path for unprivileged ublk
2809          *
2810          * header->addr always points to the dev path buffer, and
2811          * header->dev_path_len records length of dev path buffer.
2812          */
2813         if (!header->dev_path_len || header->dev_path_len > PATH_MAX)
2814                 return -EINVAL;
2815
2816         if (header->len < header->dev_path_len)
2817                 return -EINVAL;
2818
2819         dev_path = memdup_user_nul(argp, header->dev_path_len);
2820         if (IS_ERR(dev_path))
2821                 return PTR_ERR(dev_path);
2822
2823         ret = -EINVAL;
2824         switch (_IOC_NR(cmd->cmd_op)) {
2825         case UBLK_CMD_GET_DEV_INFO:
2826         case UBLK_CMD_GET_DEV_INFO2:
2827         case UBLK_CMD_GET_QUEUE_AFFINITY:
2828         case UBLK_CMD_GET_PARAMS:
2829         case (_IOC_NR(UBLK_U_CMD_GET_FEATURES)):
2830                 mask = MAY_READ;
2831                 break;
2832         case UBLK_CMD_START_DEV:
2833         case UBLK_CMD_STOP_DEV:
2834         case UBLK_CMD_ADD_DEV:
2835         case UBLK_CMD_DEL_DEV:
2836         case UBLK_CMD_SET_PARAMS:
2837         case UBLK_CMD_START_USER_RECOVERY:
2838         case UBLK_CMD_END_USER_RECOVERY:
2839                 mask = MAY_READ | MAY_WRITE;
2840                 break;
2841         default:
2842                 goto exit;
2843         }
2844
2845         ret = ublk_char_dev_permission(ub, dev_path, mask);
2846         if (!ret) {
2847                 header->len -= header->dev_path_len;
2848                 header->addr += header->dev_path_len;
2849         }
2850         pr_devel("%s: dev id %d cmd_op %x uid %d gid %d path %s ret %d\n",
2851                         __func__, ub->ub_number, cmd->cmd_op,
2852                         ub->dev_info.owner_uid, ub->dev_info.owner_gid,
2853                         dev_path, ret);
2854 exit:
2855         kfree(dev_path);
2856         return ret;
2857 }
2858
2859 static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
2860                 unsigned int issue_flags)
2861 {
2862         const struct ublksrv_ctrl_cmd *header = io_uring_sqe_cmd(cmd->sqe);
2863         struct ublk_device *ub = NULL;
2864         u32 cmd_op = cmd->cmd_op;
2865         int ret = -EINVAL;
2866
2867         if (issue_flags & IO_URING_F_NONBLOCK)
2868                 return -EAGAIN;
2869
2870         ublk_ctrl_cmd_dump(cmd);
2871
2872         if (!(issue_flags & IO_URING_F_SQE128))
2873                 goto out;
2874
2875         ret = ublk_check_cmd_op(cmd_op);
2876         if (ret)
2877                 goto out;
2878
2879         if (cmd_op == UBLK_U_CMD_GET_FEATURES) {
2880                 ret = ublk_ctrl_get_features(cmd);
2881                 goto out;
2882         }
2883
2884         if (_IOC_NR(cmd_op) != UBLK_CMD_ADD_DEV) {
2885                 ret = -ENODEV;
2886                 ub = ublk_get_device_from_id(header->dev_id);
2887                 if (!ub)
2888                         goto out;
2889
2890                 ret = ublk_ctrl_uring_cmd_permission(ub, cmd);
2891                 if (ret)
2892                         goto put_dev;
2893         }
2894
2895         switch (_IOC_NR(cmd_op)) {
2896         case UBLK_CMD_START_DEV:
2897                 ret = ublk_ctrl_start_dev(ub, cmd);
2898                 break;
2899         case UBLK_CMD_STOP_DEV:
2900                 ret = ublk_ctrl_stop_dev(ub);
2901                 break;
2902         case UBLK_CMD_GET_DEV_INFO:
2903         case UBLK_CMD_GET_DEV_INFO2:
2904                 ret = ublk_ctrl_get_dev_info(ub, cmd);
2905                 break;
2906         case UBLK_CMD_ADD_DEV:
2907                 ret = ublk_ctrl_add_dev(cmd);
2908                 break;
2909         case UBLK_CMD_DEL_DEV:
2910                 ret = ublk_ctrl_del_dev(&ub);
2911                 break;
2912         case UBLK_CMD_GET_QUEUE_AFFINITY:
2913                 ret = ublk_ctrl_get_queue_affinity(ub, cmd);
2914                 break;
2915         case UBLK_CMD_GET_PARAMS:
2916                 ret = ublk_ctrl_get_params(ub, cmd);
2917                 break;
2918         case UBLK_CMD_SET_PARAMS:
2919                 ret = ublk_ctrl_set_params(ub, cmd);
2920                 break;
2921         case UBLK_CMD_START_USER_RECOVERY:
2922                 ret = ublk_ctrl_start_recovery(ub, cmd);
2923                 break;
2924         case UBLK_CMD_END_USER_RECOVERY:
2925                 ret = ublk_ctrl_end_recovery(ub, cmd);
2926                 break;
2927         default:
2928                 ret = -ENOTSUPP;
2929                 break;
2930         }
2931
2932  put_dev:
2933         if (ub)
2934                 ublk_put_device(ub);
2935  out:
2936         io_uring_cmd_done(cmd, ret, 0, issue_flags);
2937         pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n",
2938                         __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id);
2939         return -EIOCBQUEUED;
2940 }
2941
2942 static const struct file_operations ublk_ctl_fops = {
2943         .open           = nonseekable_open,
2944         .uring_cmd      = ublk_ctrl_uring_cmd,
2945         .owner          = THIS_MODULE,
2946         .llseek         = noop_llseek,
2947 };
2948
2949 static struct miscdevice ublk_misc = {
2950         .minor          = MISC_DYNAMIC_MINOR,
2951         .name           = "ublk-control",
2952         .fops           = &ublk_ctl_fops,
2953 };
2954
2955 static int __init ublk_init(void)
2956 {
2957         int ret;
2958
2959         BUILD_BUG_ON((u64)UBLKSRV_IO_BUF_OFFSET +
2960                         UBLKSRV_IO_BUF_TOTAL_SIZE < UBLKSRV_IO_BUF_OFFSET);
2961
2962         init_waitqueue_head(&ublk_idr_wq);
2963
2964         ret = misc_register(&ublk_misc);
2965         if (ret)
2966                 return ret;
2967
2968         ret = alloc_chrdev_region(&ublk_chr_devt, 0, UBLK_MINORS, "ublk-char");
2969         if (ret)
2970                 goto unregister_mis;
2971
2972         ret = class_register(&ublk_chr_class);
2973         if (ret)
2974                 goto free_chrdev_region;
2975
2976         return 0;
2977
2978 free_chrdev_region:
2979         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2980 unregister_mis:
2981         misc_deregister(&ublk_misc);
2982         return ret;
2983 }
2984
2985 static void __exit ublk_exit(void)
2986 {
2987         struct ublk_device *ub;
2988         int id;
2989
2990         idr_for_each_entry(&ublk_index_idr, ub, id)
2991                 ublk_remove(ub);
2992
2993         class_unregister(&ublk_chr_class);
2994         misc_deregister(&ublk_misc);
2995
2996         idr_destroy(&ublk_index_idr);
2997         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2998 }
2999
3000 module_init(ublk_init);
3001 module_exit(ublk_exit);
3002
3003 static int ublk_set_max_ublks(const char *buf, const struct kernel_param *kp)
3004 {
3005         return param_set_uint_minmax(buf, kp, 0, UBLK_MAX_UBLKS);
3006 }
3007
3008 static int ublk_get_max_ublks(char *buf, const struct kernel_param *kp)
3009 {
3010         return sysfs_emit(buf, "%u\n", ublks_max);
3011 }
3012
3013 static const struct kernel_param_ops ublk_max_ublks_ops = {
3014         .set = ublk_set_max_ublks,
3015         .get = ublk_get_max_ublks,
3016 };
3017
3018 module_param_cb(ublks_max, &ublk_max_ublks_ops, &ublks_max, 0644);
3019 MODULE_PARM_DESC(ublks_max, "max number of ublk devices allowed to add(default: 64)");
3020
3021 MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>");
3022 MODULE_LICENSE("GPL");