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