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