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.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 <uapi/linux/ublk_cmd.h>
  47
  48 #define UBLK_MINORS             (1U << MINORBITS)
  49
  50 /* All UBLK_F_* have to be included into UBLK_F_ALL */
  51 #define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY \
  52                 | UBLK_F_URING_CMD_COMP_IN_TASK \
  53                 | UBLK_F_NEED_GET_DATA \
  54                 | UBLK_F_USER_RECOVERY \
  55                 | UBLK_F_USER_RECOVERY_REISSUE \
  56                 | UBLK_F_UNPRIVILEGED_DEV)
  57
  58 /* All UBLK_PARAM_TYPE_* should be included here */
  59 #define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | \
  60                 UBLK_PARAM_TYPE_DISCARD | UBLK_PARAM_TYPE_DEVT)
  61
  62 struct ublk_rq_data {
  63         struct llist_node node;
  64         struct callback_head work;
  65 };
  66
  67 struct ublk_uring_cmd_pdu {
  68         struct ublk_queue *ubq;
  69 };
  70
  71 /*
  72  * io command is active: sqe cmd is received, and its cqe isn't done
  73  *
  74  * If the flag is set, the io command is owned by ublk driver, and waited
  75  * for incoming blk-mq request from the ublk block device.
  76  *
  77  * If the flag is cleared, the io command will be completed, and owned by
  78  * ublk server.
  79  */
  80 #define UBLK_IO_FLAG_ACTIVE     0x01
  81
  82 /*
  83  * IO command is completed via cqe, and it is being handled by ublksrv, and
  84  * not committed yet
  85  *
  86  * Basically exclusively with UBLK_IO_FLAG_ACTIVE, so can be served for
  87  * cross verification
  88  */
  89 #define UBLK_IO_FLAG_OWNED_BY_SRV 0x02
  90
  91 /*
  92  * IO command is aborted, so this flag is set in case of
  93  * !UBLK_IO_FLAG_ACTIVE.
  94  *
  95  * After this flag is observed, any pending or new incoming request
  96  * associated with this io command will be failed immediately
  97  */
  98 #define UBLK_IO_FLAG_ABORTED 0x04
  99
 100 /*
 101  * UBLK_IO_FLAG_NEED_GET_DATA is set because IO command requires
 102  * get data buffer address from ublksrv.
 103  *
 104  * Then, bio data could be copied into this data buffer for a WRITE request
 105  * after the IO command is issued again and UBLK_IO_FLAG_NEED_GET_DATA is unset.
 106  */
 107 #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
 108
 109 struct ublk_io {
 110         /* userspace buffer address from io cmd */
 111         __u64   addr;
 112         unsigned int flags;
 113         int res;
 114
 115         struct io_uring_cmd *cmd;
 116 };
 117
 118 struct ublk_queue {
 119         int q_id;
 120         int q_depth;
 121
 122         unsigned long flags;
 123         struct task_struct      *ubq_daemon;
 124         char *io_cmd_buf;
 125
 126         struct llist_head       io_cmds;
 127
 128         unsigned long io_addr;  /* mapped vm address */
 129         unsigned int max_io_sz;
 130         bool force_abort;
 131         unsigned short nr_io_ready;     /* how many ios setup */
 132         struct ublk_device *dev;
 133         struct ublk_io ios[];
 134 };
 135
 136 #define UBLK_DAEMON_MONITOR_PERIOD      (5 * HZ)
 137
 138 struct ublk_device {
 139         struct gendisk          *ub_disk;
 140
 141         char    *__queues;
 142
 143         unsigned int    queue_size;
 144         struct ublksrv_ctrl_dev_info    dev_info;
 145
 146         struct blk_mq_tag_set   tag_set;
 147
 148         struct cdev             cdev;
 149         struct device           cdev_dev;
 150
 151 #define UB_STATE_OPEN           0
 152 #define UB_STATE_USED           1
 153 #define UB_STATE_DELETED        2
 154         unsigned long           state;
 155         int                     ub_number;
 156
 157         struct mutex            mutex;
 158
 159         spinlock_t              mm_lock;
 160         struct mm_struct        *mm;
 161
 162         struct ublk_params      params;
 163
 164         struct completion       completion;
 165         unsigned int            nr_queues_ready;
 166         unsigned int            nr_privileged_daemon;
 167
 168         /*
 169          * Our ubq->daemon may be killed without any notification, so
 170          * monitor each queue's daemon periodically
 171          */
 172         struct delayed_work     monitor_work;
 173         struct work_struct      quiesce_work;
 174         struct work_struct      stop_work;
 175 };
 176
 177 /* header of ublk_params */
 178 struct ublk_params_header {
 179         __u32   len;
 180         __u32   types;
 181 };
 182
 183 static dev_t ublk_chr_devt;
 184 static struct class *ublk_chr_class;
 185
 186 static DEFINE_IDR(ublk_index_idr);
 187 static DEFINE_SPINLOCK(ublk_idr_lock);
 188 static wait_queue_head_t ublk_idr_wq;   /* wait until one idr is freed */
 189
 190 static DEFINE_MUTEX(ublk_ctl_mutex);
 191
 192 /*
 193  * Max ublk devices allowed to add
 194  *
 195  * It can be extended to one per-user limit in future or even controlled
 196  * by cgroup.
 197  */
 198 static unsigned int ublks_max = 64;
 199 static unsigned int ublks_added;        /* protected by ublk_ctl_mutex */
 200
 201 static struct miscdevice ublk_misc;
 202
 203 static void ublk_dev_param_basic_apply(struct ublk_device *ub)
 204 {
 205         struct request_queue *q = ub->ub_disk->queue;
 206         const struct ublk_param_basic *p = &ub->params.basic;
 207
 208         blk_queue_logical_block_size(q, 1 << p->logical_bs_shift);
 209         blk_queue_physical_block_size(q, 1 << p->physical_bs_shift);
 210         blk_queue_io_min(q, 1 << p->io_min_shift);
 211         blk_queue_io_opt(q, 1 << p->io_opt_shift);
 212
 213         blk_queue_write_cache(q, p->attrs & UBLK_ATTR_VOLATILE_CACHE,
 214                         p->attrs & UBLK_ATTR_FUA);
 215         if (p->attrs & UBLK_ATTR_ROTATIONAL)
 216                 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
 217         else
 218                 blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
 219
 220         blk_queue_max_hw_sectors(q, p->max_sectors);
 221         blk_queue_chunk_sectors(q, p->chunk_sectors);
 222         blk_queue_virt_boundary(q, p->virt_boundary_mask);
 223
 224         if (p->attrs & UBLK_ATTR_READ_ONLY)
 225                 set_disk_ro(ub->ub_disk, true);
 226
 227         set_capacity(ub->ub_disk, p->dev_sectors);
 228 }
 229
 230 static void ublk_dev_param_discard_apply(struct ublk_device *ub)
 231 {
 232         struct request_queue *q = ub->ub_disk->queue;
 233         const struct ublk_param_discard *p = &ub->params.discard;
 234
 235         q->limits.discard_alignment = p->discard_alignment;
 236         q->limits.discard_granularity = p->discard_granularity;
 237         blk_queue_max_discard_sectors(q, p->max_discard_sectors);
 238         blk_queue_max_write_zeroes_sectors(q,
 239                         p->max_write_zeroes_sectors);
 240         blk_queue_max_discard_segments(q, p->max_discard_segments);
 241 }
 242
 243 static int ublk_validate_params(const struct ublk_device *ub)
 244 {
 245         /* basic param is the only one which must be set */
 246         if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
 247                 const struct ublk_param_basic *p = &ub->params.basic;
 248
 249                 if (p->logical_bs_shift > PAGE_SHIFT)
 250                         return -EINVAL;
 251
 252                 if (p->logical_bs_shift > p->physical_bs_shift)
 253                         return -EINVAL;
 254
 255                 if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
 256                         return -EINVAL;
 257         } else
 258                 return -EINVAL;
 259
 260         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD) {
 261                 const struct ublk_param_discard *p = &ub->params.discard;
 262
 263                 /* So far, only support single segment discard */
 264                 if (p->max_discard_sectors && p->max_discard_segments != 1)
 265                         return -EINVAL;
 266
 267                 if (!p->discard_granularity)
 268                         return -EINVAL;
 269         }
 270
 271         /* dev_t is read-only */
 272         if (ub->params.types & UBLK_PARAM_TYPE_DEVT)
 273                 return -EINVAL;
 274
 275         return 0;
 276 }
 277
 278 static int ublk_apply_params(struct ublk_device *ub)
 279 {
 280         if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
 281                 return -EINVAL;
 282
 283         ublk_dev_param_basic_apply(ub);
 284
 285         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
 286                 ublk_dev_param_discard_apply(ub);
 287
 288         return 0;
 289 }
 290
 291 static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq)
 292 {
 293         if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) &&
 294                         !(ubq->flags & UBLK_F_URING_CMD_COMP_IN_TASK))
 295                 return true;
 296         return false;
 297 }
 298
 299 static inline bool ublk_need_get_data(const struct ublk_queue *ubq)
 300 {
 301         if (ubq->flags & UBLK_F_NEED_GET_DATA)
 302                 return true;
 303         return false;
 304 }
 305
 306 static struct ublk_device *ublk_get_device(struct ublk_device *ub)
 307 {
 308         if (kobject_get_unless_zero(&ub->cdev_dev.kobj))
 309                 return ub;
 310         return NULL;
 311 }
 312
 313 static void ublk_put_device(struct ublk_device *ub)
 314 {
 315         put_device(&ub->cdev_dev);
 316 }
 317
 318 static inline struct ublk_queue *ublk_get_queue(struct ublk_device *dev,
 319                 int qid)
 320 {
 321        return (struct ublk_queue *)&(dev->__queues[qid * dev->queue_size]);
 322 }
 323
 324 static inline bool ublk_rq_has_data(const struct request *rq)
 325 {
 326         return bio_has_data(rq->bio);
 327 }
 328
 329 static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq,
 330                 int tag)
 331 {
 332         return (struct ublksrv_io_desc *)
 333                 &(ubq->io_cmd_buf[tag * sizeof(struct ublksrv_io_desc)]);
 334 }
 335
 336 static inline char *ublk_queue_cmd_buf(struct ublk_device *ub, int q_id)
 337 {
 338         return ublk_get_queue(ub, q_id)->io_cmd_buf;
 339 }
 340
 341 static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
 342 {
 343         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 344
 345         return round_up(ubq->q_depth * sizeof(struct ublksrv_io_desc),
 346                         PAGE_SIZE);
 347 }
 348
 349 static inline bool ublk_queue_can_use_recovery_reissue(
 350                 struct ublk_queue *ubq)
 351 {
 352         if ((ubq->flags & UBLK_F_USER_RECOVERY) &&
 353                         (ubq->flags & UBLK_F_USER_RECOVERY_REISSUE))
 354                 return true;
 355         return false;
 356 }
 357
 358 static inline bool ublk_queue_can_use_recovery(
 359                 struct ublk_queue *ubq)
 360 {
 361         if (ubq->flags & UBLK_F_USER_RECOVERY)
 362                 return true;
 363         return false;
 364 }
 365
 366 static inline bool ublk_can_use_recovery(struct ublk_device *ub)
 367 {
 368         if (ub->dev_info.flags & UBLK_F_USER_RECOVERY)
 369                 return true;
 370         return false;
 371 }
 372
 373 static void ublk_free_disk(struct gendisk *disk)
 374 {
 375         struct ublk_device *ub = disk->private_data;
 376
 377         clear_bit(UB_STATE_USED, &ub->state);
 378         put_device(&ub->cdev_dev);
 379 }
 380
 381 static void ublk_store_owner_uid_gid(unsigned int *owner_uid,
 382                 unsigned int *owner_gid)
 383 {
 384         kuid_t uid;
 385         kgid_t gid;
 386
 387         current_uid_gid(&uid, &gid);
 388
 389         *owner_uid = from_kuid(&init_user_ns, uid);
 390         *owner_gid = from_kgid(&init_user_ns, gid);
 391 }
 392
 393 static int ublk_open(struct block_device *bdev, fmode_t mode)
 394 {
 395         struct ublk_device *ub = bdev->bd_disk->private_data;
 396
 397         if (capable(CAP_SYS_ADMIN))
 398                 return 0;
 399
 400         /*
 401          * If it is one unprivileged device, only owner can open
 402          * the disk. Otherwise it could be one trap made by one
 403          * evil user who grants this disk's privileges to other
 404          * users deliberately.
 405          *
 406          * This way is reasonable too given anyone can create
 407          * unprivileged device, and no need other's grant.
 408          */
 409         if (ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV) {
 410                 unsigned int curr_uid, curr_gid;
 411
 412                 ublk_store_owner_uid_gid(&curr_uid, &curr_gid);
 413
 414                 if (curr_uid != ub->dev_info.owner_uid || curr_gid !=
 415                                 ub->dev_info.owner_gid)
 416                         return -EPERM;
 417         }
 418
 419         return 0;
 420 }
 421
 422 static const struct block_device_operations ub_fops = {
 423         .owner =        THIS_MODULE,
 424         .open =         ublk_open,
 425         .free_disk =    ublk_free_disk,
 426 };
 427
 428 #define UBLK_MAX_PIN_PAGES      32
 429
 430 struct ublk_map_data {
 431         const struct ublk_queue *ubq;
 432         const struct request *rq;
 433         const struct ublk_io *io;
 434         unsigned max_bytes;
 435 };
 436
 437 struct ublk_io_iter {
 438         struct page *pages[UBLK_MAX_PIN_PAGES];
 439         unsigned pg_off;        /* offset in the 1st page in pages */
 440         int nr_pages;           /* how many page pointers in pages */
 441         struct bio *bio;
 442         struct bvec_iter iter;
 443 };
 444
 445 static inline unsigned ublk_copy_io_pages(struct ublk_io_iter *data,
 446                 unsigned max_bytes, bool to_vm)
 447 {
 448         const unsigned total = min_t(unsigned, max_bytes,
 449                         PAGE_SIZE - data->pg_off +
 450                         ((data->nr_pages - 1) << PAGE_SHIFT));
 451         unsigned done = 0;
 452         unsigned pg_idx = 0;
 453
 454         while (done < total) {
 455                 struct bio_vec bv = bio_iter_iovec(data->bio, data->iter);
 456                 const unsigned int bytes = min3(bv.bv_len, total - done,
 457                                 (unsigned)(PAGE_SIZE - data->pg_off));
 458                 void *bv_buf = bvec_kmap_local(&bv);
 459                 void *pg_buf = kmap_local_page(data->pages[pg_idx]);
 460
 461                 if (to_vm)
 462                         memcpy(pg_buf + data->pg_off, bv_buf, bytes);
 463                 else
 464                         memcpy(bv_buf, pg_buf + data->pg_off, bytes);
 465
 466                 kunmap_local(pg_buf);
 467                 kunmap_local(bv_buf);
 468
 469                 /* advance page array */
 470                 data->pg_off += bytes;
 471                 if (data->pg_off == PAGE_SIZE) {
 472                         pg_idx += 1;
 473                         data->pg_off = 0;
 474                 }
 475
 476                 done += bytes;
 477
 478                 /* advance bio */
 479                 bio_advance_iter_single(data->bio, &data->iter, bytes);
 480                 if (!data->iter.bi_size) {
 481                         data->bio = data->bio->bi_next;
 482                         if (data->bio == NULL)
 483                                 break;
 484                         data->iter = data->bio->bi_iter;
 485                 }
 486         }
 487
 488         return done;
 489 }
 490
 491 static inline int ublk_copy_user_pages(struct ublk_map_data *data,
 492                 bool to_vm)
 493 {
 494         const unsigned int gup_flags = to_vm ? FOLL_WRITE : 0;
 495         const unsigned long start_vm = data->io->addr;
 496         unsigned int done = 0;
 497         struct ublk_io_iter iter = {
 498                 .pg_off = start_vm & (PAGE_SIZE - 1),
 499                 .bio    = data->rq->bio,
 500                 .iter   = data->rq->bio->bi_iter,
 501         };
 502         const unsigned int nr_pages = round_up(data->max_bytes +
 503                         (start_vm & (PAGE_SIZE - 1)), PAGE_SIZE) >> PAGE_SHIFT;
 504
 505         while (done < nr_pages) {
 506                 const unsigned to_pin = min_t(unsigned, UBLK_MAX_PIN_PAGES,
 507                                 nr_pages - done);
 508                 unsigned i, len;
 509
 510                 iter.nr_pages = get_user_pages_fast(start_vm +
 511                                 (done << PAGE_SHIFT), to_pin, gup_flags,
 512                                 iter.pages);
 513                 if (iter.nr_pages <= 0)
 514                         return done == 0 ? iter.nr_pages : done;
 515                 len = ublk_copy_io_pages(&iter, data->max_bytes, to_vm);
 516                 for (i = 0; i < iter.nr_pages; i++) {
 517                         if (to_vm)
 518                                 set_page_dirty(iter.pages[i]);
 519                         put_page(iter.pages[i]);
 520                 }
 521                 data->max_bytes -= len;
 522                 done += iter.nr_pages;
 523         }
 524
 525         return done;
 526 }
 527
 528 static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
 529                 struct ublk_io *io)
 530 {
 531         const unsigned int rq_bytes = blk_rq_bytes(req);
 532         /*
 533          * no zero copy, we delay copy WRITE request data into ublksrv
 534          * context and the big benefit is that pinning pages in current
 535          * context is pretty fast, see ublk_pin_user_pages
 536          */
 537         if (req_op(req) != REQ_OP_WRITE && req_op(req) != REQ_OP_FLUSH)
 538                 return rq_bytes;
 539
 540         if (ublk_rq_has_data(req)) {
 541                 struct ublk_map_data data = {
 542                         .ubq    =       ubq,
 543                         .rq     =       req,
 544                         .io     =       io,
 545                         .max_bytes =    rq_bytes,
 546                 };
 547
 548                 ublk_copy_user_pages(&data, true);
 549
 550                 return rq_bytes - data.max_bytes;
 551         }
 552         return rq_bytes;
 553 }
 554
 555 static int ublk_unmap_io(const struct ublk_queue *ubq,
 556                 const struct request *req,
 557                 struct ublk_io *io)
 558 {
 559         const unsigned int rq_bytes = blk_rq_bytes(req);
 560
 561         if (req_op(req) == REQ_OP_READ && ublk_rq_has_data(req)) {
 562                 struct ublk_map_data data = {
 563                         .ubq    =       ubq,
 564                         .rq     =       req,
 565                         .io     =       io,
 566                         .max_bytes =    io->res,
 567                 };
 568
 569                 WARN_ON_ONCE(io->res > rq_bytes);
 570
 571                 ublk_copy_user_pages(&data, false);
 572
 573                 return io->res - data.max_bytes;
 574         }
 575         return rq_bytes;
 576 }
 577
 578 static inline unsigned int ublk_req_build_flags(struct request *req)
 579 {
 580         unsigned flags = 0;
 581
 582         if (req->cmd_flags & REQ_FAILFAST_DEV)
 583                 flags |= UBLK_IO_F_FAILFAST_DEV;
 584
 585         if (req->cmd_flags & REQ_FAILFAST_TRANSPORT)
 586                 flags |= UBLK_IO_F_FAILFAST_TRANSPORT;
 587
 588         if (req->cmd_flags & REQ_FAILFAST_DRIVER)
 589                 flags |= UBLK_IO_F_FAILFAST_DRIVER;
 590
 591         if (req->cmd_flags & REQ_META)
 592                 flags |= UBLK_IO_F_META;
 593
 594         if (req->cmd_flags & REQ_FUA)
 595                 flags |= UBLK_IO_F_FUA;
 596
 597         if (req->cmd_flags & REQ_NOUNMAP)
 598                 flags |= UBLK_IO_F_NOUNMAP;
 599
 600         if (req->cmd_flags & REQ_SWAP)
 601                 flags |= UBLK_IO_F_SWAP;
 602
 603         return flags;
 604 }
 605
 606 static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 607 {
 608         struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
 609         struct ublk_io *io = &ubq->ios[req->tag];
 610         u32 ublk_op;
 611
 612         switch (req_op(req)) {
 613         case REQ_OP_READ:
 614                 ublk_op = UBLK_IO_OP_READ;
 615                 break;
 616         case REQ_OP_WRITE:
 617                 ublk_op = UBLK_IO_OP_WRITE;
 618                 break;
 619         case REQ_OP_FLUSH:
 620                 ublk_op = UBLK_IO_OP_FLUSH;
 621                 break;
 622         case REQ_OP_DISCARD:
 623                 ublk_op = UBLK_IO_OP_DISCARD;
 624                 break;
 625         case REQ_OP_WRITE_ZEROES:
 626                 ublk_op = UBLK_IO_OP_WRITE_ZEROES;
 627                 break;
 628         default:
 629                 return BLK_STS_IOERR;
 630         }
 631
 632         /* need to translate since kernel may change */
 633         iod->op_flags = ublk_op | ublk_req_build_flags(req);
 634         iod->nr_sectors = blk_rq_sectors(req);
 635         iod->start_sector = blk_rq_pos(req);
 636         iod->addr = io->addr;
 637
 638         return BLK_STS_OK;
 639 }
 640
 641 static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu(
 642                 struct io_uring_cmd *ioucmd)
 643 {
 644         return (struct ublk_uring_cmd_pdu *)&ioucmd->pdu;
 645 }
 646
 647 static inline bool ubq_daemon_is_dying(struct ublk_queue *ubq)
 648 {
 649         return ubq->ubq_daemon->flags & PF_EXITING;
 650 }
 651
 652 /* todo: handle partial completion */
 653 static void ublk_complete_rq(struct request *req)
 654 {
 655         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 656         struct ublk_io *io = &ubq->ios[req->tag];
 657         unsigned int unmapped_bytes;
 658
 659         /* failed read IO if nothing is read */
 660         if (!io->res && req_op(req) == REQ_OP_READ)
 661                 io->res = -EIO;
 662
 663         if (io->res < 0) {
 664                 blk_mq_end_request(req, errno_to_blk_status(io->res));
 665                 return;
 666         }
 667
 668         /*
 669          * FLUSH, DISCARD or WRITE_ZEROES usually won't return bytes returned, so end them
 670          * directly.
 671          *
 672          * Both the two needn't unmap.
 673          */
 674         if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE) {
 675                 blk_mq_end_request(req, BLK_STS_OK);
 676                 return;
 677         }
 678
 679         /* for READ request, writing data in iod->addr to rq buffers */
 680         unmapped_bytes = ublk_unmap_io(ubq, req, io);
 681
 682         /*
 683          * Extremely impossible since we got data filled in just before
 684          *
 685          * Re-read simply for this unlikely case.
 686          */
 687         if (unlikely(unmapped_bytes < io->res))
 688                 io->res = unmapped_bytes;
 689
 690         if (blk_update_request(req, BLK_STS_OK, io->res))
 691                 blk_mq_requeue_request(req, true);
 692         else
 693                 __blk_mq_end_request(req, BLK_STS_OK);
 694 }
 695
 696 /*
 697  * Since __ublk_rq_task_work always fails requests immediately during
 698  * exiting, __ublk_fail_req() is only called from abort context during
 699  * exiting. So lock is unnecessary.
 700  *
 701  * Also aborting may not be started yet, keep in mind that one failed
 702  * request may be issued by block layer again.
 703  */
 704 static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
 705                 struct request *req)
 706 {
 707         WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
 708
 709         if (!(io->flags & UBLK_IO_FLAG_ABORTED)) {
 710                 io->flags |= UBLK_IO_FLAG_ABORTED;
 711                 if (ublk_queue_can_use_recovery_reissue(ubq))
 712                         blk_mq_requeue_request(req, false);
 713                 else
 714                         blk_mq_end_request(req, BLK_STS_IOERR);
 715         }
 716 }
 717
 718 static void ubq_complete_io_cmd(struct ublk_io *io, int res)
 719 {
 720         /* mark this cmd owned by ublksrv */
 721         io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV;
 722
 723         /*
 724          * clear ACTIVE since we are done with this sqe/cmd slot
 725          * We can only accept io cmd in case of being not active.
 726          */
 727         io->flags &= ~UBLK_IO_FLAG_ACTIVE;
 728
 729         /* tell ublksrv one io request is coming */
 730         io_uring_cmd_done(io->cmd, res, 0);
 731 }
 732
 733 #define UBLK_REQUEUE_DELAY_MS   3
 734
 735 static inline void __ublk_abort_rq(struct ublk_queue *ubq,
 736                 struct request *rq)
 737 {
 738         /* We cannot process this rq so just requeue it. */
 739         if (ublk_queue_can_use_recovery(ubq))
 740                 blk_mq_requeue_request(rq, false);
 741         else
 742                 blk_mq_end_request(rq, BLK_STS_IOERR);
 743
 744         mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0);
 745 }
 746
 747 static inline void __ublk_rq_task_work(struct request *req)
 748 {
 749         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 750         int tag = req->tag;
 751         struct ublk_io *io = &ubq->ios[tag];
 752         unsigned int mapped_bytes;
 753
 754         pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",
 755                         __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 756                         ublk_get_iod(ubq, req->tag)->addr);
 757
 758         /*
 759          * Task is exiting if either:
 760          *
 761          * (1) current != ubq_daemon.
 762          * io_uring_cmd_complete_in_task() tries to run task_work
 763          * in a workqueue if ubq_daemon(cmd's task) is PF_EXITING.
 764          *
 765          * (2) current->flags & PF_EXITING.
 766          */
 767         if (unlikely(current != ubq->ubq_daemon || current->flags & PF_EXITING)) {
 768                 __ublk_abort_rq(ubq, req);
 769                 return;
 770         }
 771
 772         if (ublk_need_get_data(ubq) &&
 773                         (req_op(req) == REQ_OP_WRITE ||
 774                         req_op(req) == REQ_OP_FLUSH)) {
 775                 /*
 776                  * We have not handled UBLK_IO_NEED_GET_DATA command yet,
 777                  * so immepdately pass UBLK_IO_RES_NEED_GET_DATA to ublksrv
 778                  * and notify it.
 779                  */
 780                 if (!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA)) {
 781                         io->flags |= UBLK_IO_FLAG_NEED_GET_DATA;
 782                         pr_devel("%s: need get data. op %d, qid %d tag %d io_flags %x\n",
 783                                         __func__, io->cmd->cmd_op, ubq->q_id,
 784                                         req->tag, io->flags);
 785                         ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA);
 786                         return;
 787                 }
 788                 /*
 789                  * We have handled UBLK_IO_NEED_GET_DATA command,
 790                  * so clear UBLK_IO_FLAG_NEED_GET_DATA now and just
 791                  * do the copy work.
 792                  */
 793                 io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA;
 794                 /* update iod->addr because ublksrv may have passed a new io buffer */
 795                 ublk_get_iod(ubq, req->tag)->addr = io->addr;
 796                 pr_devel("%s: update iod->addr: op %d, qid %d tag %d io_flags %x addr %llx\n",
 797                                 __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 798                                 ublk_get_iod(ubq, req->tag)->addr);
 799         }
 800
 801         mapped_bytes = ublk_map_io(ubq, req, io);
 802
 803         /* partially mapped, update io descriptor */
 804         if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
 805                 /*
 806                  * Nothing mapped, retry until we succeed.
 807                  *
 808                  * We may never succeed in mapping any bytes here because
 809                  * of OOM. TODO: reserve one buffer with single page pinned
 810                  * for providing forward progress guarantee.
 811                  */
 812                 if (unlikely(!mapped_bytes)) {
 813                         blk_mq_requeue_request(req, false);
 814                         blk_mq_delay_kick_requeue_list(req->q,
 815                                         UBLK_REQUEUE_DELAY_MS);
 816                         return;
 817                 }
 818
 819                 ublk_get_iod(ubq, req->tag)->nr_sectors =
 820                         mapped_bytes >> 9;
 821         }
 822
 823         ubq_complete_io_cmd(io, UBLK_IO_RES_OK);
 824 }
 825
 826 static inline void ublk_forward_io_cmds(struct ublk_queue *ubq)
 827 {
 828         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
 829         struct ublk_rq_data *data, *tmp;
 830
 831         io_cmds = llist_reverse_order(io_cmds);
 832         llist_for_each_entry_safe(data, tmp, io_cmds, node)
 833                 __ublk_rq_task_work(blk_mq_rq_from_pdu(data));
 834 }
 835
 836 static inline void ublk_abort_io_cmds(struct ublk_queue *ubq)
 837 {
 838         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
 839         struct ublk_rq_data *data, *tmp;
 840
 841         llist_for_each_entry_safe(data, tmp, io_cmds, node)
 842                 __ublk_abort_rq(ubq, blk_mq_rq_from_pdu(data));
 843 }
 844
 845 static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd)
 846 {
 847         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 848         struct ublk_queue *ubq = pdu->ubq;
 849
 850         ublk_forward_io_cmds(ubq);
 851 }
 852
 853 static void ublk_rq_task_work_fn(struct callback_head *work)
 854 {
 855         struct ublk_rq_data *data = container_of(work,
 856                         struct ublk_rq_data, work);
 857         struct request *req = blk_mq_rq_from_pdu(data);
 858         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 859
 860         ublk_forward_io_cmds(ubq);
 861 }
 862
 863 static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq)
 864 {
 865         struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
 866         struct ublk_io *io;
 867
 868         if (!llist_add(&data->node, &ubq->io_cmds))
 869                 return;
 870
 871         io = &ubq->ios[rq->tag];
 872         /*
 873          * If the check pass, we know that this is a re-issued request aborted
 874          * previously in monitor_work because the ubq_daemon(cmd's task) is
 875          * PF_EXITING. We cannot call io_uring_cmd_complete_in_task() anymore
 876          * because this ioucmd's io_uring context may be freed now if no inflight
 877          * ioucmd exists. Otherwise we may cause null-deref in ctx->fallback_work.
 878          *
 879          * Note: monitor_work sets UBLK_IO_FLAG_ABORTED and ends this request(releasing
 880          * the tag). Then the request is re-started(allocating the tag) and we are here.
 881          * Since releasing/allocating a tag implies smp_mb(), finding UBLK_IO_FLAG_ABORTED
 882          * guarantees that here is a re-issued request aborted previously.
 883          */
 884         if (unlikely(io->flags & UBLK_IO_FLAG_ABORTED)) {
 885                 ublk_abort_io_cmds(ubq);
 886         } else if (ublk_can_use_task_work(ubq)) {
 887                 if (task_work_add(ubq->ubq_daemon, &data->work,
 888                                         TWA_SIGNAL_NO_IPI))
 889                         ublk_abort_io_cmds(ubq);
 890         } else {
 891                 struct io_uring_cmd *cmd = io->cmd;
 892                 struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 893
 894                 pdu->ubq = ubq;
 895                 io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb);
 896         }
 897 }
 898
 899 static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
 900                 const struct blk_mq_queue_data *bd)
 901 {
 902         struct ublk_queue *ubq = hctx->driver_data;
 903         struct request *rq = bd->rq;
 904         blk_status_t res;
 905
 906         /* fill iod to slot in io cmd buffer */
 907         res = ublk_setup_iod(ubq, rq);
 908         if (unlikely(res != BLK_STS_OK))
 909                 return BLK_STS_IOERR;
 910
 911         /* With recovery feature enabled, force_abort is set in
 912          * ublk_stop_dev() before calling del_gendisk(). We have to
 913          * abort all requeued and new rqs here to let del_gendisk()
 914          * move on. Besides, we cannot not call io_uring_cmd_complete_in_task()
 915          * to avoid UAF on io_uring ctx.
 916          *
 917          * Note: force_abort is guaranteed to be seen because it is set
 918          * before request queue is unqiuesced.
 919          */
 920         if (ublk_queue_can_use_recovery(ubq) && unlikely(ubq->force_abort))
 921                 return BLK_STS_IOERR;
 922
 923         blk_mq_start_request(bd->rq);
 924
 925         if (unlikely(ubq_daemon_is_dying(ubq))) {
 926                 __ublk_abort_rq(ubq, rq);
 927                 return BLK_STS_OK;
 928         }
 929
 930         ublk_queue_cmd(ubq, rq);
 931
 932         return BLK_STS_OK;
 933 }
 934
 935 static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
 936                 unsigned int hctx_idx)
 937 {
 938         struct ublk_device *ub = driver_data;
 939         struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num);
 940
 941         hctx->driver_data = ubq;
 942         return 0;
 943 }
 944
 945 static int ublk_init_rq(struct blk_mq_tag_set *set, struct request *req,
 946                 unsigned int hctx_idx, unsigned int numa_node)
 947 {
 948         struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 949
 950         init_task_work(&data->work, ublk_rq_task_work_fn);
 951         return 0;
 952 }
 953
 954 static const struct blk_mq_ops ublk_mq_ops = {
 955         .queue_rq       = ublk_queue_rq,
 956         .init_hctx      = ublk_init_hctx,
 957         .init_request   = ublk_init_rq,
 958 };
 959
 960 static int ublk_ch_open(struct inode *inode, struct file *filp)
 961 {
 962         struct ublk_device *ub = container_of(inode->i_cdev,
 963                         struct ublk_device, cdev);
 964
 965         if (test_and_set_bit(UB_STATE_OPEN, &ub->state))
 966                 return -EBUSY;
 967         filp->private_data = ub;
 968         return 0;
 969 }
 970
 971 static int ublk_ch_release(struct inode *inode, struct file *filp)
 972 {
 973         struct ublk_device *ub = filp->private_data;
 974
 975         clear_bit(UB_STATE_OPEN, &ub->state);
 976         return 0;
 977 }
 978
 979 /* map pre-allocated per-queue cmd buffer to ublksrv daemon */
 980 static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
 981 {
 982         struct ublk_device *ub = filp->private_data;
 983         size_t sz = vma->vm_end - vma->vm_start;
 984         unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc);
 985         unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT;
 986         int q_id, ret = 0;
 987
 988         spin_lock(&ub->mm_lock);
 989         if (!ub->mm)
 990                 ub->mm = current->mm;
 991         if (current->mm != ub->mm)
 992                 ret = -EINVAL;
 993         spin_unlock(&ub->mm_lock);
 994
 995         if (ret)
 996                 return ret;
 997
 998         if (vma->vm_flags & VM_WRITE)
 999                 return -EPERM;
1000
1001         end = UBLKSRV_CMD_BUF_OFFSET + ub->dev_info.nr_hw_queues * max_sz;
1002         if (phys_off < UBLKSRV_CMD_BUF_OFFSET || phys_off >= end)
1003                 return -EINVAL;
1004
1005         q_id = (phys_off - UBLKSRV_CMD_BUF_OFFSET) / max_sz;
1006         pr_devel("%s: qid %d, pid %d, addr %lx pg_off %lx sz %lu\n",
1007                         __func__, q_id, current->pid, vma->vm_start,
1008                         phys_off, (unsigned long)sz);
1009
1010         if (sz != ublk_queue_cmd_buf_size(ub, q_id))
1011                 return -EINVAL;
1012
1013         pfn = virt_to_phys(ublk_queue_cmd_buf(ub, q_id)) >> PAGE_SHIFT;
1014         return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
1015 }
1016
1017 static void ublk_commit_completion(struct ublk_device *ub,
1018                 struct ublksrv_io_cmd *ub_cmd)
1019 {
1020         u32 qid = ub_cmd->q_id, tag = ub_cmd->tag;
1021         struct ublk_queue *ubq = ublk_get_queue(ub, qid);
1022         struct ublk_io *io = &ubq->ios[tag];
1023         struct request *req;
1024
1025         /* now this cmd slot is owned by nbd driver */
1026         io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
1027         io->res = ub_cmd->result;
1028
1029         /* find the io request and complete */
1030         req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
1031
1032         if (req && likely(!blk_should_fake_timeout(req->q)))
1033                 ublk_complete_rq(req);
1034 }
1035
1036 /*
1037  * When ->ubq_daemon is exiting, either new request is ended immediately,
1038  * or any queued io command is drained, so it is safe to abort queue
1039  * lockless
1040  */
1041 static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
1042 {
1043         int i;
1044
1045         if (!ublk_get_device(ub))
1046                 return;
1047
1048         for (i = 0; i < ubq->q_depth; i++) {
1049                 struct ublk_io *io = &ubq->ios[i];
1050
1051                 if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) {
1052                         struct request *rq;
1053
1054                         /*
1055                          * Either we fail the request or ublk_rq_task_work_fn
1056                          * will do it
1057                          */
1058                         rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);
1059                         if (rq)
1060                                 __ublk_fail_req(ubq, io, rq);
1061                 }
1062         }
1063         ublk_put_device(ub);
1064 }
1065
1066 static void ublk_daemon_monitor_work(struct work_struct *work)
1067 {
1068         struct ublk_device *ub =
1069                 container_of(work, struct ublk_device, monitor_work.work);
1070         int i;
1071
1072         for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {
1073                 struct ublk_queue *ubq = ublk_get_queue(ub, i);
1074
1075                 if (ubq_daemon_is_dying(ubq)) {
1076                         if (ublk_queue_can_use_recovery(ubq))
1077                                 schedule_work(&ub->quiesce_work);
1078                         else
1079                                 schedule_work(&ub->stop_work);
1080
1081                         /* abort queue is for making forward progress */
1082                         ublk_abort_queue(ub, ubq);
1083                 }
1084         }
1085
1086         /*
1087          * We can't schedule monitor work after ub's state is not UBLK_S_DEV_LIVE.
1088          * after ublk_remove() or __ublk_quiesce_dev() is started.
1089          *
1090          * No need ub->mutex, monitor work are canceled after state is marked
1091          * as not LIVE, so new state is observed reliably.
1092          */
1093         if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1094                 schedule_delayed_work(&ub->monitor_work,
1095                                 UBLK_DAEMON_MONITOR_PERIOD);
1096 }
1097
1098 static inline bool ublk_queue_ready(struct ublk_queue *ubq)
1099 {
1100         return ubq->nr_io_ready == ubq->q_depth;
1101 }
1102
1103 static void ublk_cancel_queue(struct ublk_queue *ubq)
1104 {
1105         int i;
1106
1107         if (!ublk_queue_ready(ubq))
1108                 return;
1109
1110         for (i = 0; i < ubq->q_depth; i++) {
1111                 struct ublk_io *io = &ubq->ios[i];
1112
1113                 if (io->flags & UBLK_IO_FLAG_ACTIVE)
1114                         io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0);
1115         }
1116
1117         /* all io commands are canceled */
1118         ubq->nr_io_ready = 0;
1119 }
1120
1121 /* Cancel all pending commands, must be called after del_gendisk() returns */
1122 static void ublk_cancel_dev(struct ublk_device *ub)
1123 {
1124         int i;
1125
1126         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1127                 ublk_cancel_queue(ublk_get_queue(ub, i));
1128 }
1129
1130 static bool ublk_check_inflight_rq(struct request *rq, void *data)
1131 {
1132         bool *idle = data;
1133
1134         if (blk_mq_request_started(rq)) {
1135                 *idle = false;
1136                 return false;
1137         }
1138         return true;
1139 }
1140
1141 static void ublk_wait_tagset_rqs_idle(struct ublk_device *ub)
1142 {
1143         bool idle;
1144
1145         WARN_ON_ONCE(!blk_queue_quiesced(ub->ub_disk->queue));
1146         while (true) {
1147                 idle = true;
1148                 blk_mq_tagset_busy_iter(&ub->tag_set,
1149                                 ublk_check_inflight_rq, &idle);
1150                 if (idle)
1151                         break;
1152                 msleep(UBLK_REQUEUE_DELAY_MS);
1153         }
1154 }
1155
1156 static void __ublk_quiesce_dev(struct ublk_device *ub)
1157 {
1158         pr_devel("%s: quiesce ub: dev_id %d state %s\n",
1159                         __func__, ub->dev_info.dev_id,
1160                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1161                         "LIVE" : "QUIESCED");
1162         blk_mq_quiesce_queue(ub->ub_disk->queue);
1163         ublk_wait_tagset_rqs_idle(ub);
1164         ub->dev_info.state = UBLK_S_DEV_QUIESCED;
1165         ublk_cancel_dev(ub);
1166         /* we are going to release task_struct of ubq_daemon and resets
1167          * ->ubq_daemon to NULL. So in monitor_work, check on ubq_daemon causes UAF.
1168          * Besides, monitor_work is not necessary in QUIESCED state since we have
1169          * already scheduled quiesce_work and quiesced all ubqs.
1170          *
1171          * Do not let monitor_work schedule itself if state it QUIESCED. And we cancel
1172          * it here and re-schedule it in END_USER_RECOVERY to avoid UAF.
1173          */
1174         cancel_delayed_work_sync(&ub->monitor_work);
1175 }
1176
1177 static void ublk_quiesce_work_fn(struct work_struct *work)
1178 {
1179         struct ublk_device *ub =
1180                 container_of(work, struct ublk_device, quiesce_work);
1181
1182         mutex_lock(&ub->mutex);
1183         if (ub->dev_info.state != UBLK_S_DEV_LIVE)
1184                 goto unlock;
1185         __ublk_quiesce_dev(ub);
1186  unlock:
1187         mutex_unlock(&ub->mutex);
1188 }
1189
1190 static void ublk_unquiesce_dev(struct ublk_device *ub)
1191 {
1192         int i;
1193
1194         pr_devel("%s: unquiesce ub: dev_id %d state %s\n",
1195                         __func__, ub->dev_info.dev_id,
1196                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1197                         "LIVE" : "QUIESCED");
1198         /* quiesce_work has run. We let requeued rqs be aborted
1199          * before running fallback_wq. "force_abort" must be seen
1200          * after request queue is unqiuesced. Then del_gendisk()
1201          * can move on.
1202          */
1203         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1204                 ublk_get_queue(ub, i)->force_abort = true;
1205
1206         blk_mq_unquiesce_queue(ub->ub_disk->queue);
1207         /* We may have requeued some rqs in ublk_quiesce_queue() */
1208         blk_mq_kick_requeue_list(ub->ub_disk->queue);
1209 }
1210
1211 static void ublk_stop_dev(struct ublk_device *ub)
1212 {
1213         mutex_lock(&ub->mutex);
1214         if (ub->dev_info.state == UBLK_S_DEV_DEAD)
1215                 goto unlock;
1216         if (ublk_can_use_recovery(ub)) {
1217                 if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1218                         __ublk_quiesce_dev(ub);
1219                 ublk_unquiesce_dev(ub);
1220         }
1221         del_gendisk(ub->ub_disk);
1222         ub->dev_info.state = UBLK_S_DEV_DEAD;
1223         ub->dev_info.ublksrv_pid = -1;
1224         put_disk(ub->ub_disk);
1225         ub->ub_disk = NULL;
1226  unlock:
1227         ublk_cancel_dev(ub);
1228         mutex_unlock(&ub->mutex);
1229         cancel_delayed_work_sync(&ub->monitor_work);
1230 }
1231
1232 /* device can only be started after all IOs are ready */
1233 static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
1234 {
1235         mutex_lock(&ub->mutex);
1236         ubq->nr_io_ready++;
1237         if (ublk_queue_ready(ubq)) {
1238                 ubq->ubq_daemon = current;
1239                 get_task_struct(ubq->ubq_daemon);
1240                 ub->nr_queues_ready++;
1241
1242                 if (capable(CAP_SYS_ADMIN))
1243                         ub->nr_privileged_daemon++;
1244         }
1245         if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
1246                 complete_all(&ub->completion);
1247         mutex_unlock(&ub->mutex);
1248 }
1249
1250 static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,
1251                 int tag)
1252 {
1253         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1254         struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag);
1255
1256         ublk_queue_cmd(ubq, req);
1257 }
1258
1259 static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
1260 {
1261         struct ublksrv_io_cmd *ub_cmd = (struct ublksrv_io_cmd *)cmd->cmd;
1262         struct ublk_device *ub = cmd->file->private_data;
1263         struct ublk_queue *ubq;
1264         struct ublk_io *io;
1265         u32 cmd_op = cmd->cmd_op;
1266         unsigned tag = ub_cmd->tag;
1267         int ret = -EINVAL;
1268         struct request *req;
1269
1270         pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
1271                         __func__, cmd->cmd_op, ub_cmd->q_id, tag,
1272                         ub_cmd->result);
1273
1274         if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues)
1275                 goto out;
1276
1277         ubq = ublk_get_queue(ub, ub_cmd->q_id);
1278         if (!ubq || ub_cmd->q_id != ubq->q_id)
1279                 goto out;
1280
1281         if (ubq->ubq_daemon && ubq->ubq_daemon != current)
1282                 goto out;
1283
1284         if (tag >= ubq->q_depth)
1285                 goto out;
1286
1287         io = &ubq->ios[tag];
1288
1289         /* there is pending io cmd, something must be wrong */
1290         if (io->flags & UBLK_IO_FLAG_ACTIVE) {
1291                 ret = -EBUSY;
1292                 goto out;
1293         }
1294
1295         /*
1296          * ensure that the user issues UBLK_IO_NEED_GET_DATA
1297          * iff the driver have set the UBLK_IO_FLAG_NEED_GET_DATA.
1298          */
1299         if ((!!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA))
1300                         ^ (cmd_op == UBLK_IO_NEED_GET_DATA))
1301                 goto out;
1302
1303         switch (cmd_op) {
1304         case UBLK_IO_FETCH_REQ:
1305                 /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
1306                 if (ublk_queue_ready(ubq)) {
1307                         ret = -EBUSY;
1308                         goto out;
1309                 }
1310                 /*
1311                  * The io is being handled by server, so COMMIT_RQ is expected
1312                  * instead of FETCH_REQ
1313                  */
1314                 if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
1315                         goto out;
1316                 /* FETCH_RQ has to provide IO buffer if NEED GET DATA is not enabled */
1317                 if (!ub_cmd->addr && !ublk_need_get_data(ubq))
1318                         goto out;
1319                 io->cmd = cmd;
1320                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1321                 io->addr = ub_cmd->addr;
1322
1323                 ublk_mark_io_ready(ub, ubq);
1324                 break;
1325         case UBLK_IO_COMMIT_AND_FETCH_REQ:
1326                 req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag);
1327                 /*
1328                  * COMMIT_AND_FETCH_REQ has to provide IO buffer if NEED GET DATA is
1329                  * not enabled or it is Read IO.
1330                  */
1331                 if (!ub_cmd->addr && (!ublk_need_get_data(ubq) || req_op(req) == REQ_OP_READ))
1332                         goto out;
1333                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1334                         goto out;
1335                 io->addr = ub_cmd->addr;
1336                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1337                 io->cmd = cmd;
1338                 ublk_commit_completion(ub, ub_cmd);
1339                 break;
1340         case UBLK_IO_NEED_GET_DATA:
1341                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1342                         goto out;
1343                 io->addr = ub_cmd->addr;
1344                 io->cmd = cmd;
1345                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1346                 ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag);
1347                 break;
1348         default:
1349                 goto out;
1350         }
1351         return -EIOCBQUEUED;
1352
1353  out:
1354         io_uring_cmd_done(cmd, ret, 0);
1355         pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n",
1356                         __func__, cmd_op, tag, ret, io->flags);
1357         return -EIOCBQUEUED;
1358 }
1359
1360 static const struct file_operations ublk_ch_fops = {
1361         .owner = THIS_MODULE,
1362         .open = ublk_ch_open,
1363         .release = ublk_ch_release,
1364         .llseek = no_llseek,
1365         .uring_cmd = ublk_ch_uring_cmd,
1366         .mmap = ublk_ch_mmap,
1367 };
1368
1369 static void ublk_deinit_queue(struct ublk_device *ub, int q_id)
1370 {
1371         int size = ublk_queue_cmd_buf_size(ub, q_id);
1372         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1373
1374         if (ubq->ubq_daemon)
1375                 put_task_struct(ubq->ubq_daemon);
1376         if (ubq->io_cmd_buf)
1377                 free_pages((unsigned long)ubq->io_cmd_buf, get_order(size));
1378 }
1379
1380 static int ublk_init_queue(struct ublk_device *ub, int q_id)
1381 {
1382         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1383         gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO;
1384         void *ptr;
1385         int size;
1386
1387         ubq->flags = ub->dev_info.flags;
1388         ubq->q_id = q_id;
1389         ubq->q_depth = ub->dev_info.queue_depth;
1390         size = ublk_queue_cmd_buf_size(ub, q_id);
1391
1392         ptr = (void *) __get_free_pages(gfp_flags, get_order(size));
1393         if (!ptr)
1394                 return -ENOMEM;
1395
1396         ubq->io_cmd_buf = ptr;
1397         ubq->dev = ub;
1398         return 0;
1399 }
1400
1401 static void ublk_deinit_queues(struct ublk_device *ub)
1402 {
1403         int nr_queues = ub->dev_info.nr_hw_queues;
1404         int i;
1405
1406         if (!ub->__queues)
1407                 return;
1408
1409         for (i = 0; i < nr_queues; i++)
1410                 ublk_deinit_queue(ub, i);
1411         kfree(ub->__queues);
1412 }
1413
1414 static int ublk_init_queues(struct ublk_device *ub)
1415 {
1416         int nr_queues = ub->dev_info.nr_hw_queues;
1417         int depth = ub->dev_info.queue_depth;
1418         int ubq_size = sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io);
1419         int i, ret = -ENOMEM;
1420
1421         ub->queue_size = ubq_size;
1422         ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL);
1423         if (!ub->__queues)
1424                 return ret;
1425
1426         for (i = 0; i < nr_queues; i++) {
1427                 if (ublk_init_queue(ub, i))
1428                         goto fail;
1429         }
1430
1431         init_completion(&ub->completion);
1432         return 0;
1433
1434  fail:
1435         ublk_deinit_queues(ub);
1436         return ret;
1437 }
1438
1439 static int ublk_alloc_dev_number(struct ublk_device *ub, int idx)
1440 {
1441         int i = idx;
1442         int err;
1443
1444         spin_lock(&ublk_idr_lock);
1445         /* allocate id, if @id >= 0, we're requesting that specific id */
1446         if (i >= 0) {
1447                 err = idr_alloc(&ublk_index_idr, ub, i, i + 1, GFP_NOWAIT);
1448                 if (err == -ENOSPC)
1449                         err = -EEXIST;
1450         } else {
1451                 err = idr_alloc(&ublk_index_idr, ub, 0, 0, GFP_NOWAIT);
1452         }
1453         spin_unlock(&ublk_idr_lock);
1454
1455         if (err >= 0)
1456                 ub->ub_number = err;
1457
1458         return err;
1459 }
1460
1461 static void ublk_free_dev_number(struct ublk_device *ub)
1462 {
1463         spin_lock(&ublk_idr_lock);
1464         idr_remove(&ublk_index_idr, ub->ub_number);
1465         wake_up_all(&ublk_idr_wq);
1466         spin_unlock(&ublk_idr_lock);
1467 }
1468
1469 static void ublk_cdev_rel(struct device *dev)
1470 {
1471         struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev);
1472
1473         blk_mq_free_tag_set(&ub->tag_set);
1474         ublk_deinit_queues(ub);
1475         ublk_free_dev_number(ub);
1476         mutex_destroy(&ub->mutex);
1477         kfree(ub);
1478 }
1479
1480 static int ublk_add_chdev(struct ublk_device *ub)
1481 {
1482         struct device *dev = &ub->cdev_dev;
1483         int minor = ub->ub_number;
1484         int ret;
1485
1486         dev->parent = ublk_misc.this_device;
1487         dev->devt = MKDEV(MAJOR(ublk_chr_devt), minor);
1488         dev->class = ublk_chr_class;
1489         dev->release = ublk_cdev_rel;
1490         device_initialize(dev);
1491
1492         ret = dev_set_name(dev, "ublkc%d", minor);
1493         if (ret)
1494                 goto fail;
1495
1496         cdev_init(&ub->cdev, &ublk_ch_fops);
1497         ret = cdev_device_add(&ub->cdev, dev);
1498         if (ret)
1499                 goto fail;
1500
1501         ublks_added++;
1502         return 0;
1503  fail:
1504         put_device(dev);
1505         return ret;
1506 }
1507
1508 static void ublk_stop_work_fn(struct work_struct *work)
1509 {
1510         struct ublk_device *ub =
1511                 container_of(work, struct ublk_device, stop_work);
1512
1513         ublk_stop_dev(ub);
1514 }
1515
1516 /* align max io buffer size with PAGE_SIZE */
1517 static void ublk_align_max_io_size(struct ublk_device *ub)
1518 {
1519         unsigned int max_io_bytes = ub->dev_info.max_io_buf_bytes;
1520
1521         ub->dev_info.max_io_buf_bytes =
1522                 round_down(max_io_bytes, PAGE_SIZE);
1523 }
1524
1525 static int ublk_add_tag_set(struct ublk_device *ub)
1526 {
1527         ub->tag_set.ops = &ublk_mq_ops;
1528         ub->tag_set.nr_hw_queues = ub->dev_info.nr_hw_queues;
1529         ub->tag_set.queue_depth = ub->dev_info.queue_depth;
1530         ub->tag_set.numa_node = NUMA_NO_NODE;
1531         ub->tag_set.cmd_size = sizeof(struct ublk_rq_data);
1532         ub->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1533         ub->tag_set.driver_data = ub;
1534         return blk_mq_alloc_tag_set(&ub->tag_set);
1535 }
1536
1537 static void ublk_remove(struct ublk_device *ub)
1538 {
1539         ublk_stop_dev(ub);
1540         cancel_work_sync(&ub->stop_work);
1541         cancel_work_sync(&ub->quiesce_work);
1542         cdev_device_del(&ub->cdev, &ub->cdev_dev);
1543         put_device(&ub->cdev_dev);
1544         ublks_added--;
1545 }
1546
1547 static struct ublk_device *ublk_get_device_from_id(int idx)
1548 {
1549         struct ublk_device *ub = NULL;
1550
1551         if (idx < 0)
1552                 return NULL;
1553
1554         spin_lock(&ublk_idr_lock);
1555         ub = idr_find(&ublk_index_idr, idx);
1556         if (ub)
1557                 ub = ublk_get_device(ub);
1558         spin_unlock(&ublk_idr_lock);
1559
1560         return ub;
1561 }
1562
1563 static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
1564 {
1565         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1566         int ublksrv_pid = (int)header->data[0];
1567         struct gendisk *disk;
1568         int ret = -EINVAL;
1569
1570         if (ublksrv_pid <= 0)
1571                 return -EINVAL;
1572
1573         wait_for_completion_interruptible(&ub->completion);
1574
1575         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
1576
1577         mutex_lock(&ub->mutex);
1578         if (ub->dev_info.state == UBLK_S_DEV_LIVE ||
1579             test_bit(UB_STATE_USED, &ub->state)) {
1580                 ret = -EEXIST;
1581                 goto out_unlock;
1582         }
1583
1584         disk = blk_mq_alloc_disk(&ub->tag_set, NULL);
1585         if (IS_ERR(disk)) {
1586                 ret = PTR_ERR(disk);
1587                 goto out_unlock;
1588         }
1589         sprintf(disk->disk_name, "ublkb%d", ub->ub_number);
1590         disk->fops = &ub_fops;
1591         disk->private_data = ub;
1592
1593         ub->dev_info.ublksrv_pid = ublksrv_pid;
1594         ub->ub_disk = disk;
1595
1596         ret = ublk_apply_params(ub);
1597         if (ret)
1598                 goto out_put_disk;
1599
1600         /* don't probe partitions if any one ubq daemon is un-trusted */
1601         if (ub->nr_privileged_daemon != ub->nr_queues_ready)
1602                 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
1603
1604         get_device(&ub->cdev_dev);
1605         ret = add_disk(disk);
1606         if (ret) {
1607                 /*
1608                  * Has to drop the reference since ->free_disk won't be
1609                  * called in case of add_disk failure.
1610                  */
1611                 ublk_put_device(ub);
1612                 goto out_put_disk;
1613         }
1614         set_bit(UB_STATE_USED, &ub->state);
1615         ub->dev_info.state = UBLK_S_DEV_LIVE;
1616 out_put_disk:
1617         if (ret)
1618                 put_disk(disk);
1619 out_unlock:
1620         mutex_unlock(&ub->mutex);
1621         return ret;
1622 }
1623
1624 static int ublk_ctrl_get_queue_affinity(struct ublk_device *ub,
1625                 struct io_uring_cmd *cmd)
1626 {
1627         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1628         void __user *argp = (void __user *)(unsigned long)header->addr;
1629         cpumask_var_t cpumask;
1630         unsigned long queue;
1631         unsigned int retlen;
1632         unsigned int i;
1633         int ret;
1634
1635         if (header->len * BITS_PER_BYTE < nr_cpu_ids)
1636                 return -EINVAL;
1637         if (header->len & (sizeof(unsigned long)-1))
1638                 return -EINVAL;
1639         if (!header->addr)
1640                 return -EINVAL;
1641
1642         queue = header->data[0];
1643         if (queue >= ub->dev_info.nr_hw_queues)
1644                 return -EINVAL;
1645
1646         if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
1647                 return -ENOMEM;
1648
1649         for_each_possible_cpu(i) {
1650                 if (ub->tag_set.map[HCTX_TYPE_DEFAULT].mq_map[i] == queue)
1651                         cpumask_set_cpu(i, cpumask);
1652         }
1653
1654         ret = -EFAULT;
1655         retlen = min_t(unsigned short, header->len, cpumask_size());
1656         if (copy_to_user(argp, cpumask, retlen))
1657                 goto out_free_cpumask;
1658         if (retlen != header->len &&
1659             clear_user(argp + retlen, header->len - retlen))
1660                 goto out_free_cpumask;
1661
1662         ret = 0;
1663 out_free_cpumask:
1664         free_cpumask_var(cpumask);
1665         return ret;
1666 }
1667
1668 static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info)
1669 {
1670         pr_devel("%s: dev id %d flags %llx\n", __func__,
1671                         info->dev_id, info->flags);
1672         pr_devel("\t nr_hw_queues %d queue_depth %d\n",
1673                         info->nr_hw_queues, info->queue_depth);
1674 }
1675
1676 static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
1677 {
1678         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1679         void __user *argp = (void __user *)(unsigned long)header->addr;
1680         struct ublksrv_ctrl_dev_info info;
1681         struct ublk_device *ub;
1682         int ret = -EINVAL;
1683
1684         if (header->len < sizeof(info) || !header->addr)
1685                 return -EINVAL;
1686         if (header->queue_id != (u16)-1) {
1687                 pr_warn("%s: queue_id is wrong %x\n",
1688                         __func__, header->queue_id);
1689                 return -EINVAL;
1690         }
1691
1692         if (copy_from_user(&info, argp, sizeof(info)))
1693                 return -EFAULT;
1694
1695         if (capable(CAP_SYS_ADMIN))
1696                 info.flags &= ~UBLK_F_UNPRIVILEGED_DEV;
1697         else if (!(info.flags & UBLK_F_UNPRIVILEGED_DEV))
1698                 return -EPERM;
1699
1700         /* the created device is always owned by current user */
1701         ublk_store_owner_uid_gid(&info.owner_uid, &info.owner_gid);
1702
1703         if (header->dev_id != info.dev_id) {
1704                 pr_warn("%s: dev id not match %u %u\n",
1705                         __func__, header->dev_id, info.dev_id);
1706                 return -EINVAL;
1707         }
1708
1709         ublk_dump_dev_info(&info);
1710
1711         ret = mutex_lock_killable(&ublk_ctl_mutex);
1712         if (ret)
1713                 return ret;
1714
1715         ret = -EACCES;
1716         if (ublks_added >= ublks_max)
1717                 goto out_unlock;
1718
1719         ret = -ENOMEM;
1720         ub = kzalloc(sizeof(*ub), GFP_KERNEL);
1721         if (!ub)
1722                 goto out_unlock;
1723         mutex_init(&ub->mutex);
1724         spin_lock_init(&ub->mm_lock);
1725         INIT_WORK(&ub->quiesce_work, ublk_quiesce_work_fn);
1726         INIT_WORK(&ub->stop_work, ublk_stop_work_fn);
1727         INIT_DELAYED_WORK(&ub->monitor_work, ublk_daemon_monitor_work);
1728
1729         ret = ublk_alloc_dev_number(ub, header->dev_id);
1730         if (ret < 0)
1731                 goto out_free_ub;
1732
1733         memcpy(&ub->dev_info, &info, sizeof(info));
1734
1735         /* update device id */
1736         ub->dev_info.dev_id = ub->ub_number;
1737
1738         /*
1739          * 64bit flags will be copied back to userspace as feature
1740          * negotiation result, so have to clear flags which driver
1741          * doesn't support yet, then userspace can get correct flags
1742          * (features) to handle.
1743          */
1744         ub->dev_info.flags &= UBLK_F_ALL;
1745
1746         if (!IS_BUILTIN(CONFIG_BLK_DEV_UBLK))
1747                 ub->dev_info.flags |= UBLK_F_URING_CMD_COMP_IN_TASK;
1748
1749         /* We are not ready to support zero copy */
1750         ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
1751
1752         ub->dev_info.nr_hw_queues = min_t(unsigned int,
1753                         ub->dev_info.nr_hw_queues, nr_cpu_ids);
1754         ublk_align_max_io_size(ub);
1755
1756         ret = ublk_init_queues(ub);
1757         if (ret)
1758                 goto out_free_dev_number;
1759
1760         ret = ublk_add_tag_set(ub);
1761         if (ret)
1762                 goto out_deinit_queues;
1763
1764         ret = -EFAULT;
1765         if (copy_to_user(argp, &ub->dev_info, sizeof(info)))
1766                 goto out_free_tag_set;
1767
1768         /*
1769          * Add the char dev so that ublksrv daemon can be setup.
1770          * ublk_add_chdev() will cleanup everything if it fails.
1771          */
1772         ret = ublk_add_chdev(ub);
1773         goto out_unlock;
1774
1775 out_free_tag_set:
1776         blk_mq_free_tag_set(&ub->tag_set);
1777 out_deinit_queues:
1778         ublk_deinit_queues(ub);
1779 out_free_dev_number:
1780         ublk_free_dev_number(ub);
1781 out_free_ub:
1782         mutex_destroy(&ub->mutex);
1783         kfree(ub);
1784 out_unlock:
1785         mutex_unlock(&ublk_ctl_mutex);
1786         return ret;
1787 }
1788
1789 static inline bool ublk_idr_freed(int id)
1790 {
1791         void *ptr;
1792
1793         spin_lock(&ublk_idr_lock);
1794         ptr = idr_find(&ublk_index_idr, id);
1795         spin_unlock(&ublk_idr_lock);
1796
1797         return ptr == NULL;
1798 }
1799
1800 static int ublk_ctrl_del_dev(struct ublk_device **p_ub)
1801 {
1802         struct ublk_device *ub = *p_ub;
1803         int idx = ub->ub_number;
1804         int ret;
1805
1806         ret = mutex_lock_killable(&ublk_ctl_mutex);
1807         if (ret)
1808                 return ret;
1809
1810         if (!test_bit(UB_STATE_DELETED, &ub->state)) {
1811                 ublk_remove(ub);
1812                 set_bit(UB_STATE_DELETED, &ub->state);
1813         }
1814
1815         /* Mark the reference as consumed */
1816         *p_ub = NULL;
1817         ublk_put_device(ub);
1818         mutex_unlock(&ublk_ctl_mutex);
1819
1820         /*
1821          * Wait until the idr is removed, then it can be reused after
1822          * DEL_DEV command is returned.
1823          *
1824          * If we returns because of user interrupt, future delete command
1825          * may come:
1826          *
1827          * - the device number isn't freed, this device won't or needn't
1828          *   be deleted again, since UB_STATE_DELETED is set, and device
1829          *   will be released after the last reference is dropped
1830          *
1831          * - the device number is freed already, we will not find this
1832          *   device via ublk_get_device_from_id()
1833          */
1834         wait_event_interruptible(ublk_idr_wq, ublk_idr_freed(idx));
1835
1836         return 0;
1837 }
1838
1839 static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd)
1840 {
1841         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1842
1843         pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n",
1844                         __func__, cmd->cmd_op, header->dev_id, header->queue_id,
1845                         header->data[0], header->addr, header->len);
1846 }
1847
1848 static int ublk_ctrl_stop_dev(struct ublk_device *ub)
1849 {
1850         ublk_stop_dev(ub);
1851         cancel_work_sync(&ub->stop_work);
1852         cancel_work_sync(&ub->quiesce_work);
1853
1854         return 0;
1855 }
1856
1857 static int ublk_ctrl_get_dev_info(struct ublk_device *ub,
1858                 struct io_uring_cmd *cmd)
1859 {
1860         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1861         void __user *argp = (void __user *)(unsigned long)header->addr;
1862
1863         if (header->len < sizeof(struct ublksrv_ctrl_dev_info) || !header->addr)
1864                 return -EINVAL;
1865
1866         if (copy_to_user(argp, &ub->dev_info, sizeof(ub->dev_info)))
1867                 return -EFAULT;
1868
1869         return 0;
1870 }
1871
1872 /* TYPE_DEVT is readonly, so fill it up before returning to userspace */
1873 static void ublk_ctrl_fill_params_devt(struct ublk_device *ub)
1874 {
1875         ub->params.devt.char_major = MAJOR(ub->cdev_dev.devt);
1876         ub->params.devt.char_minor = MINOR(ub->cdev_dev.devt);
1877
1878         if (ub->ub_disk) {
1879                 ub->params.devt.disk_major = MAJOR(disk_devt(ub->ub_disk));
1880                 ub->params.devt.disk_minor = MINOR(disk_devt(ub->ub_disk));
1881         } else {
1882                 ub->params.devt.disk_major = 0;
1883                 ub->params.devt.disk_minor = 0;
1884         }
1885         ub->params.types |= UBLK_PARAM_TYPE_DEVT;
1886 }
1887
1888 static int ublk_ctrl_get_params(struct ublk_device *ub,
1889                 struct io_uring_cmd *cmd)
1890 {
1891         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1892         void __user *argp = (void __user *)(unsigned long)header->addr;
1893         struct ublk_params_header ph;
1894         int ret;
1895
1896         if (header->len <= sizeof(ph) || !header->addr)
1897                 return -EINVAL;
1898
1899         if (copy_from_user(&ph, argp, sizeof(ph)))
1900                 return -EFAULT;
1901
1902         if (ph.len > header->len || !ph.len)
1903                 return -EINVAL;
1904
1905         if (ph.len > sizeof(struct ublk_params))
1906                 ph.len = sizeof(struct ublk_params);
1907
1908         mutex_lock(&ub->mutex);
1909         ublk_ctrl_fill_params_devt(ub);
1910         if (copy_to_user(argp, &ub->params, ph.len))
1911                 ret = -EFAULT;
1912         else
1913                 ret = 0;
1914         mutex_unlock(&ub->mutex);
1915
1916         return ret;
1917 }
1918
1919 static int ublk_ctrl_set_params(struct ublk_device *ub,
1920                 struct io_uring_cmd *cmd)
1921 {
1922         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1923         void __user *argp = (void __user *)(unsigned long)header->addr;
1924         struct ublk_params_header ph;
1925         int ret = -EFAULT;
1926
1927         if (header->len <= sizeof(ph) || !header->addr)
1928                 return -EINVAL;
1929
1930         if (copy_from_user(&ph, argp, sizeof(ph)))
1931                 return -EFAULT;
1932
1933         if (ph.len > header->len || !ph.len || !ph.types)
1934                 return -EINVAL;
1935
1936         if (ph.len > sizeof(struct ublk_params))
1937                 ph.len = sizeof(struct ublk_params);
1938
1939         /* parameters can only be changed when device isn't live */
1940         mutex_lock(&ub->mutex);
1941         if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
1942                 ret = -EACCES;
1943         } else if (copy_from_user(&ub->params, argp, ph.len)) {
1944                 ret = -EFAULT;
1945         } else {
1946                 /* clear all we don't support yet */
1947                 ub->params.types &= UBLK_PARAM_TYPE_ALL;
1948                 ret = ublk_validate_params(ub);
1949         }
1950         mutex_unlock(&ub->mutex);
1951
1952         return ret;
1953 }
1954
1955 static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
1956 {
1957         int i;
1958
1959         WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));
1960         /* All old ioucmds have to be completed */
1961         WARN_ON_ONCE(ubq->nr_io_ready);
1962         /* old daemon is PF_EXITING, put it now */
1963         put_task_struct(ubq->ubq_daemon);
1964         /* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */
1965         ubq->ubq_daemon = NULL;
1966
1967         for (i = 0; i < ubq->q_depth; i++) {
1968                 struct ublk_io *io = &ubq->ios[i];
1969
1970                 /* forget everything now and be ready for new FETCH_REQ */
1971                 io->flags = 0;
1972                 io->cmd = NULL;
1973                 io->addr = 0;
1974         }
1975 }
1976
1977 static int ublk_ctrl_start_recovery(struct ublk_device *ub,
1978                 struct io_uring_cmd *cmd)
1979 {
1980         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1981         int ret = -EINVAL;
1982         int i;
1983
1984         mutex_lock(&ub->mutex);
1985         if (!ublk_can_use_recovery(ub))
1986                 goto out_unlock;
1987         /*
1988          * START_RECOVERY is only allowd after:
1989          *
1990          * (1) UB_STATE_OPEN is not set, which means the dying process is exited
1991          *     and related io_uring ctx is freed so file struct of /dev/ublkcX is
1992          *     released.
1993          *
1994          * (2) UBLK_S_DEV_QUIESCED is set, which means the quiesce_work:
1995          *     (a)has quiesced request queue
1996          *     (b)has requeued every inflight rqs whose io_flags is ACTIVE
1997          *     (c)has requeued/aborted every inflight rqs whose io_flags is NOT ACTIVE
1998          *     (d)has completed/camceled all ioucmds owned by ther dying process
1999          */
2000         if (test_bit(UB_STATE_OPEN, &ub->state) ||
2001                         ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
2002                 ret = -EBUSY;
2003                 goto out_unlock;
2004         }
2005         pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id);
2006         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
2007                 ublk_queue_reinit(ub, ublk_get_queue(ub, i));
2008         /* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */
2009         ub->mm = NULL;
2010         ub->nr_queues_ready = 0;
2011         ub->nr_privileged_daemon = 0;
2012         init_completion(&ub->completion);
2013         ret = 0;
2014  out_unlock:
2015         mutex_unlock(&ub->mutex);
2016         return ret;
2017 }
2018
2019 static int ublk_ctrl_end_recovery(struct ublk_device *ub,
2020                 struct io_uring_cmd *cmd)
2021 {
2022         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
2023         int ublksrv_pid = (int)header->data[0];
2024         int ret = -EINVAL;
2025
2026         pr_devel("%s: Waiting for new ubq_daemons(nr: %d) are ready, dev id %d...\n",
2027                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
2028         /* wait until new ubq_daemon sending all FETCH_REQ */
2029         wait_for_completion_interruptible(&ub->completion);
2030         pr_devel("%s: All new ubq_daemons(nr: %d) are ready, dev id %d\n",
2031                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
2032
2033         mutex_lock(&ub->mutex);
2034         if (!ublk_can_use_recovery(ub))
2035                 goto out_unlock;
2036
2037         if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
2038                 ret = -EBUSY;
2039                 goto out_unlock;
2040         }
2041         ub->dev_info.ublksrv_pid = ublksrv_pid;
2042         pr_devel("%s: new ublksrv_pid %d, dev id %d\n",
2043                         __func__, ublksrv_pid, header->dev_id);
2044         blk_mq_unquiesce_queue(ub->ub_disk->queue);
2045         pr_devel("%s: queue unquiesced, dev id %d.\n",
2046                         __func__, header->dev_id);
2047         blk_mq_kick_requeue_list(ub->ub_disk->queue);
2048         ub->dev_info.state = UBLK_S_DEV_LIVE;
2049         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
2050         ret = 0;
2051  out_unlock:
2052         mutex_unlock(&ub->mutex);
2053         return ret;
2054 }
2055
2056 /*
2057  * All control commands are sent via /dev/ublk-control, so we have to check
2058  * the destination device's permission
2059  */
2060 static int ublk_char_dev_permission(struct ublk_device *ub,
2061                 const char *dev_path, int mask)
2062 {
2063         int err;
2064         struct path path;
2065         struct kstat stat;
2066
2067         err = kern_path(dev_path, LOOKUP_FOLLOW, &path);
2068         if (err)
2069                 return err;
2070
2071         err = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
2072         if (err)
2073                 goto exit;
2074
2075         err = -EPERM;
2076         if (stat.rdev != ub->cdev_dev.devt || !S_ISCHR(stat.mode))
2077                 goto exit;
2078
2079         err = inode_permission(&nop_mnt_idmap,
2080                         d_backing_inode(path.dentry), mask);
2081 exit:
2082         path_put(&path);
2083         return err;
2084 }
2085
2086 static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
2087                 struct io_uring_cmd *cmd)
2088 {
2089         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
2090         bool unprivileged = ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV;
2091         void __user *argp = (void __user *)(unsigned long)header->addr;
2092         char *dev_path = NULL;
2093         int ret = 0;
2094         int mask;
2095
2096         if (!unprivileged) {
2097                 if (!capable(CAP_SYS_ADMIN))
2098                         return -EPERM;
2099                 /*
2100                  * The new added command of UBLK_CMD_GET_DEV_INFO2 includes
2101                  * char_dev_path in payload too, since userspace may not
2102                  * know if the specified device is created as unprivileged
2103                  * mode.
2104                  */
2105                 if (cmd->cmd_op != UBLK_CMD_GET_DEV_INFO2)
2106                         return 0;
2107         }
2108
2109         /*
2110          * User has to provide the char device path for unprivileged ublk
2111          *
2112          * header->addr always points to the dev path buffer, and
2113          * header->dev_path_len records length of dev path buffer.
2114          */
2115         if (!header->dev_path_len || header->dev_path_len > PATH_MAX)
2116                 return -EINVAL;
2117
2118         if (header->len < header->dev_path_len)
2119                 return -EINVAL;
2120
2121         dev_path = kmalloc(header->dev_path_len + 1, GFP_KERNEL);
2122         if (!dev_path)
2123                 return -ENOMEM;
2124
2125         ret = -EFAULT;
2126         if (copy_from_user(dev_path, argp, header->dev_path_len))
2127                 goto exit;
2128         dev_path[header->dev_path_len] = 0;
2129
2130         ret = -EINVAL;
2131         switch (cmd->cmd_op) {
2132         case UBLK_CMD_GET_DEV_INFO:
2133         case UBLK_CMD_GET_DEV_INFO2:
2134         case UBLK_CMD_GET_QUEUE_AFFINITY:
2135         case UBLK_CMD_GET_PARAMS:
2136                 mask = MAY_READ;
2137                 break;
2138         case UBLK_CMD_START_DEV:
2139         case UBLK_CMD_STOP_DEV:
2140         case UBLK_CMD_ADD_DEV:
2141         case UBLK_CMD_DEL_DEV:
2142         case UBLK_CMD_SET_PARAMS:
2143         case UBLK_CMD_START_USER_RECOVERY:
2144         case UBLK_CMD_END_USER_RECOVERY:
2145                 mask = MAY_READ | MAY_WRITE;
2146                 break;
2147         default:
2148                 goto exit;
2149         }
2150
2151         ret = ublk_char_dev_permission(ub, dev_path, mask);
2152         if (!ret) {
2153                 header->len -= header->dev_path_len;
2154                 header->addr += header->dev_path_len;
2155         }
2156         pr_devel("%s: dev id %d cmd_op %x uid %d gid %d path %s ret %d\n",
2157                         __func__, ub->ub_number, cmd->cmd_op,
2158                         ub->dev_info.owner_uid, ub->dev_info.owner_gid,
2159                         dev_path, ret);
2160 exit:
2161         kfree(dev_path);
2162         return ret;
2163 }
2164
2165 static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
2166                 unsigned int issue_flags)
2167 {
2168         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
2169         struct ublk_device *ub = NULL;
2170         int ret = -EINVAL;
2171
2172         if (issue_flags & IO_URING_F_NONBLOCK)
2173                 return -EAGAIN;
2174
2175         ublk_ctrl_cmd_dump(cmd);
2176
2177         if (!(issue_flags & IO_URING_F_SQE128))
2178                 goto out;
2179
2180         if (cmd->cmd_op != UBLK_CMD_ADD_DEV) {
2181                 ret = -ENODEV;
2182                 ub = ublk_get_device_from_id(header->dev_id);
2183                 if (!ub)
2184                         goto out;
2185
2186                 ret = ublk_ctrl_uring_cmd_permission(ub, cmd);
2187         } else {
2188                 /* ADD_DEV permission check is done in command handler */
2189                 ret = 0;
2190         }
2191
2192         if (ret)
2193                 goto put_dev;
2194
2195         switch (cmd->cmd_op) {
2196         case UBLK_CMD_START_DEV:
2197                 ret = ublk_ctrl_start_dev(ub, cmd);
2198                 break;
2199         case UBLK_CMD_STOP_DEV:
2200                 ret = ublk_ctrl_stop_dev(ub);
2201                 break;
2202         case UBLK_CMD_GET_DEV_INFO:
2203         case UBLK_CMD_GET_DEV_INFO2:
2204                 ret = ublk_ctrl_get_dev_info(ub, cmd);
2205                 break;
2206         case UBLK_CMD_ADD_DEV:
2207                 ret = ublk_ctrl_add_dev(cmd);
2208                 break;
2209         case UBLK_CMD_DEL_DEV:
2210                 ret = ublk_ctrl_del_dev(&ub);
2211                 break;
2212         case UBLK_CMD_GET_QUEUE_AFFINITY:
2213                 ret = ublk_ctrl_get_queue_affinity(ub, cmd);
2214                 break;
2215         case UBLK_CMD_GET_PARAMS:
2216                 ret = ublk_ctrl_get_params(ub, cmd);
2217                 break;
2218         case UBLK_CMD_SET_PARAMS:
2219                 ret = ublk_ctrl_set_params(ub, cmd);
2220                 break;
2221         case UBLK_CMD_START_USER_RECOVERY:
2222                 ret = ublk_ctrl_start_recovery(ub, cmd);
2223                 break;
2224         case UBLK_CMD_END_USER_RECOVERY:
2225                 ret = ublk_ctrl_end_recovery(ub, cmd);
2226                 break;
2227         default:
2228                 ret = -ENOTSUPP;
2229                 break;
2230         }
2231
2232  put_dev:
2233         if (ub)
2234                 ublk_put_device(ub);
2235  out:
2236         io_uring_cmd_done(cmd, ret, 0);
2237         pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n",
2238                         __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id);
2239         return -EIOCBQUEUED;
2240 }
2241
2242 static const struct file_operations ublk_ctl_fops = {
2243         .open           = nonseekable_open,
2244         .uring_cmd      = ublk_ctrl_uring_cmd,
2245         .owner          = THIS_MODULE,
2246         .llseek         = noop_llseek,
2247 };
2248
2249 static struct miscdevice ublk_misc = {
2250         .minor          = MISC_DYNAMIC_MINOR,
2251         .name           = "ublk-control",
2252         .fops           = &ublk_ctl_fops,
2253 };
2254
2255 static int __init ublk_init(void)
2256 {
2257         int ret;
2258
2259         init_waitqueue_head(&ublk_idr_wq);
2260
2261         ret = misc_register(&ublk_misc);
2262         if (ret)
2263                 return ret;
2264
2265         ret = alloc_chrdev_region(&ublk_chr_devt, 0, UBLK_MINORS, "ublk-char");
2266         if (ret)
2267                 goto unregister_mis;
2268
2269         ublk_chr_class = class_create(THIS_MODULE, "ublk-char");
2270         if (IS_ERR(ublk_chr_class)) {
2271                 ret = PTR_ERR(ublk_chr_class);
2272                 goto free_chrdev_region;
2273         }
2274         return 0;
2275
2276 free_chrdev_region:
2277         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2278 unregister_mis:
2279         misc_deregister(&ublk_misc);
2280         return ret;
2281 }
2282
2283 static void __exit ublk_exit(void)
2284 {
2285         struct ublk_device *ub;
2286         int id;
2287
2288         idr_for_each_entry(&ublk_index_idr, ub, id)
2289                 ublk_remove(ub);
2290
2291         class_destroy(ublk_chr_class);
2292         misc_deregister(&ublk_misc);
2293
2294         idr_destroy(&ublk_index_idr);
2295         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2296 }
2297
2298 module_init(ublk_init);
2299 module_exit(ublk_exit);
2300
2301 module_param(ublks_max, int, 0444);
2302 MODULE_PARM_DESC(ublks_max, "max number of ublk devices allowed to add(default: 64)");
2303
2304 MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>");
2305 MODULE_LICENSE("GPL");