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         blk_status_t res = BLK_STS_OK;
 659
 660         /* failed read IO if nothing is read */
 661         if (!io->res && req_op(req) == REQ_OP_READ)
 662                 io->res = -EIO;
 663
 664         if (io->res < 0) {
 665                 res = errno_to_blk_status(io->res);
 666                 goto exit;
 667         }
 668
 669         /*
 670          * FLUSH, DISCARD or WRITE_ZEROES usually won't return bytes returned, so end them
 671          * directly.
 672          *
 673          * Both the two needn't unmap.
 674          */
 675         if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE)
 676                 goto exit;
 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         return;
 695 exit:
 696         blk_mq_end_request(req, res);
 697 }
 698
 699 /*
 700  * Since __ublk_rq_task_work always fails requests immediately during
 701  * exiting, __ublk_fail_req() is only called from abort context during
 702  * exiting. So lock is unnecessary.
 703  *
 704  * Also aborting may not be started yet, keep in mind that one failed
 705  * request may be issued by block layer again.
 706  */
 707 static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
 708                 struct request *req)
 709 {
 710         WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
 711
 712         if (!(io->flags & UBLK_IO_FLAG_ABORTED)) {
 713                 io->flags |= UBLK_IO_FLAG_ABORTED;
 714                 if (ublk_queue_can_use_recovery_reissue(ubq))
 715                         blk_mq_requeue_request(req, false);
 716                 else
 717                         blk_mq_end_request(req, BLK_STS_IOERR);
 718         }
 719 }
 720
 721 static void ubq_complete_io_cmd(struct ublk_io *io, int res)
 722 {
 723         /* mark this cmd owned by ublksrv */
 724         io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV;
 725
 726         /*
 727          * clear ACTIVE since we are done with this sqe/cmd slot
 728          * We can only accept io cmd in case of being not active.
 729          */
 730         io->flags &= ~UBLK_IO_FLAG_ACTIVE;
 731
 732         /* tell ublksrv one io request is coming */
 733         io_uring_cmd_done(io->cmd, res, 0);
 734 }
 735
 736 #define UBLK_REQUEUE_DELAY_MS   3
 737
 738 static inline void __ublk_abort_rq(struct ublk_queue *ubq,
 739                 struct request *rq)
 740 {
 741         /* We cannot process this rq so just requeue it. */
 742         if (ublk_queue_can_use_recovery(ubq))
 743                 blk_mq_requeue_request(rq, false);
 744         else
 745                 blk_mq_end_request(rq, BLK_STS_IOERR);
 746
 747         mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0);
 748 }
 749
 750 static inline void __ublk_rq_task_work(struct request *req)
 751 {
 752         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 753         int tag = req->tag;
 754         struct ublk_io *io = &ubq->ios[tag];
 755         unsigned int mapped_bytes;
 756
 757         pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",
 758                         __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 759                         ublk_get_iod(ubq, req->tag)->addr);
 760
 761         /*
 762          * Task is exiting if either:
 763          *
 764          * (1) current != ubq_daemon.
 765          * io_uring_cmd_complete_in_task() tries to run task_work
 766          * in a workqueue if ubq_daemon(cmd's task) is PF_EXITING.
 767          *
 768          * (2) current->flags & PF_EXITING.
 769          */
 770         if (unlikely(current != ubq->ubq_daemon || current->flags & PF_EXITING)) {
 771                 __ublk_abort_rq(ubq, req);
 772                 return;
 773         }
 774
 775         if (ublk_need_get_data(ubq) &&
 776                         (req_op(req) == REQ_OP_WRITE ||
 777                         req_op(req) == REQ_OP_FLUSH)) {
 778                 /*
 779                  * We have not handled UBLK_IO_NEED_GET_DATA command yet,
 780                  * so immepdately pass UBLK_IO_RES_NEED_GET_DATA to ublksrv
 781                  * and notify it.
 782                  */
 783                 if (!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA)) {
 784                         io->flags |= UBLK_IO_FLAG_NEED_GET_DATA;
 785                         pr_devel("%s: need get data. op %d, qid %d tag %d io_flags %x\n",
 786                                         __func__, io->cmd->cmd_op, ubq->q_id,
 787                                         req->tag, io->flags);
 788                         ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA);
 789                         return;
 790                 }
 791                 /*
 792                  * We have handled UBLK_IO_NEED_GET_DATA command,
 793                  * so clear UBLK_IO_FLAG_NEED_GET_DATA now and just
 794                  * do the copy work.
 795                  */
 796                 io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA;
 797                 /* update iod->addr because ublksrv may have passed a new io buffer */
 798                 ublk_get_iod(ubq, req->tag)->addr = io->addr;
 799                 pr_devel("%s: update iod->addr: op %d, qid %d tag %d io_flags %x addr %llx\n",
 800                                 __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 801                                 ublk_get_iod(ubq, req->tag)->addr);
 802         }
 803
 804         mapped_bytes = ublk_map_io(ubq, req, io);
 805
 806         /* partially mapped, update io descriptor */
 807         if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
 808                 /*
 809                  * Nothing mapped, retry until we succeed.
 810                  *
 811                  * We may never succeed in mapping any bytes here because
 812                  * of OOM. TODO: reserve one buffer with single page pinned
 813                  * for providing forward progress guarantee.
 814                  */
 815                 if (unlikely(!mapped_bytes)) {
 816                         blk_mq_requeue_request(req, false);
 817                         blk_mq_delay_kick_requeue_list(req->q,
 818                                         UBLK_REQUEUE_DELAY_MS);
 819                         return;
 820                 }
 821
 822                 ublk_get_iod(ubq, req->tag)->nr_sectors =
 823                         mapped_bytes >> 9;
 824         }
 825
 826         ubq_complete_io_cmd(io, UBLK_IO_RES_OK);
 827 }
 828
 829 static inline void ublk_forward_io_cmds(struct ublk_queue *ubq)
 830 {
 831         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
 832         struct ublk_rq_data *data, *tmp;
 833
 834         io_cmds = llist_reverse_order(io_cmds);
 835         llist_for_each_entry_safe(data, tmp, io_cmds, node)
 836                 __ublk_rq_task_work(blk_mq_rq_from_pdu(data));
 837 }
 838
 839 static inline void ublk_abort_io_cmds(struct ublk_queue *ubq)
 840 {
 841         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
 842         struct ublk_rq_data *data, *tmp;
 843
 844         llist_for_each_entry_safe(data, tmp, io_cmds, node)
 845                 __ublk_abort_rq(ubq, blk_mq_rq_from_pdu(data));
 846 }
 847
 848 static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd)
 849 {
 850         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 851         struct ublk_queue *ubq = pdu->ubq;
 852
 853         ublk_forward_io_cmds(ubq);
 854 }
 855
 856 static void ublk_rq_task_work_fn(struct callback_head *work)
 857 {
 858         struct ublk_rq_data *data = container_of(work,
 859                         struct ublk_rq_data, work);
 860         struct request *req = blk_mq_rq_from_pdu(data);
 861         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 862
 863         ublk_forward_io_cmds(ubq);
 864 }
 865
 866 static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq)
 867 {
 868         struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
 869         struct ublk_io *io;
 870
 871         if (!llist_add(&data->node, &ubq->io_cmds))
 872                 return;
 873
 874         io = &ubq->ios[rq->tag];
 875         /*
 876          * If the check pass, we know that this is a re-issued request aborted
 877          * previously in monitor_work because the ubq_daemon(cmd's task) is
 878          * PF_EXITING. We cannot call io_uring_cmd_complete_in_task() anymore
 879          * because this ioucmd's io_uring context may be freed now if no inflight
 880          * ioucmd exists. Otherwise we may cause null-deref in ctx->fallback_work.
 881          *
 882          * Note: monitor_work sets UBLK_IO_FLAG_ABORTED and ends this request(releasing
 883          * the tag). Then the request is re-started(allocating the tag) and we are here.
 884          * Since releasing/allocating a tag implies smp_mb(), finding UBLK_IO_FLAG_ABORTED
 885          * guarantees that here is a re-issued request aborted previously.
 886          */
 887         if (unlikely(io->flags & UBLK_IO_FLAG_ABORTED)) {
 888                 ublk_abort_io_cmds(ubq);
 889         } else if (ublk_can_use_task_work(ubq)) {
 890                 if (task_work_add(ubq->ubq_daemon, &data->work,
 891                                         TWA_SIGNAL_NO_IPI))
 892                         ublk_abort_io_cmds(ubq);
 893         } else {
 894                 struct io_uring_cmd *cmd = io->cmd;
 895                 struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 896
 897                 pdu->ubq = ubq;
 898                 io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb);
 899         }
 900 }
 901
 902 static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
 903                 const struct blk_mq_queue_data *bd)
 904 {
 905         struct ublk_queue *ubq = hctx->driver_data;
 906         struct request *rq = bd->rq;
 907         blk_status_t res;
 908
 909         /* fill iod to slot in io cmd buffer */
 910         res = ublk_setup_iod(ubq, rq);
 911         if (unlikely(res != BLK_STS_OK))
 912                 return BLK_STS_IOERR;
 913
 914         /* With recovery feature enabled, force_abort is set in
 915          * ublk_stop_dev() before calling del_gendisk(). We have to
 916          * abort all requeued and new rqs here to let del_gendisk()
 917          * move on. Besides, we cannot not call io_uring_cmd_complete_in_task()
 918          * to avoid UAF on io_uring ctx.
 919          *
 920          * Note: force_abort is guaranteed to be seen because it is set
 921          * before request queue is unqiuesced.
 922          */
 923         if (ublk_queue_can_use_recovery(ubq) && unlikely(ubq->force_abort))
 924                 return BLK_STS_IOERR;
 925
 926         blk_mq_start_request(bd->rq);
 927
 928         if (unlikely(ubq_daemon_is_dying(ubq))) {
 929                 __ublk_abort_rq(ubq, rq);
 930                 return BLK_STS_OK;
 931         }
 932
 933         ublk_queue_cmd(ubq, rq);
 934
 935         return BLK_STS_OK;
 936 }
 937
 938 static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
 939                 unsigned int hctx_idx)
 940 {
 941         struct ublk_device *ub = driver_data;
 942         struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num);
 943
 944         hctx->driver_data = ubq;
 945         return 0;
 946 }
 947
 948 static int ublk_init_rq(struct blk_mq_tag_set *set, struct request *req,
 949                 unsigned int hctx_idx, unsigned int numa_node)
 950 {
 951         struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 952
 953         init_task_work(&data->work, ublk_rq_task_work_fn);
 954         return 0;
 955 }
 956
 957 static const struct blk_mq_ops ublk_mq_ops = {
 958         .queue_rq       = ublk_queue_rq,
 959         .init_hctx      = ublk_init_hctx,
 960         .init_request   = ublk_init_rq,
 961 };
 962
 963 static int ublk_ch_open(struct inode *inode, struct file *filp)
 964 {
 965         struct ublk_device *ub = container_of(inode->i_cdev,
 966                         struct ublk_device, cdev);
 967
 968         if (test_and_set_bit(UB_STATE_OPEN, &ub->state))
 969                 return -EBUSY;
 970         filp->private_data = ub;
 971         return 0;
 972 }
 973
 974 static int ublk_ch_release(struct inode *inode, struct file *filp)
 975 {
 976         struct ublk_device *ub = filp->private_data;
 977
 978         clear_bit(UB_STATE_OPEN, &ub->state);
 979         return 0;
 980 }
 981
 982 /* map pre-allocated per-queue cmd buffer to ublksrv daemon */
 983 static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
 984 {
 985         struct ublk_device *ub = filp->private_data;
 986         size_t sz = vma->vm_end - vma->vm_start;
 987         unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc);
 988         unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT;
 989         int q_id, ret = 0;
 990
 991         spin_lock(&ub->mm_lock);
 992         if (!ub->mm)
 993                 ub->mm = current->mm;
 994         if (current->mm != ub->mm)
 995                 ret = -EINVAL;
 996         spin_unlock(&ub->mm_lock);
 997
 998         if (ret)
 999                 return ret;
1000
1001         if (vma->vm_flags & VM_WRITE)
1002                 return -EPERM;
1003
1004         end = UBLKSRV_CMD_BUF_OFFSET + ub->dev_info.nr_hw_queues * max_sz;
1005         if (phys_off < UBLKSRV_CMD_BUF_OFFSET || phys_off >= end)
1006                 return -EINVAL;
1007
1008         q_id = (phys_off - UBLKSRV_CMD_BUF_OFFSET) / max_sz;
1009         pr_devel("%s: qid %d, pid %d, addr %lx pg_off %lx sz %lu\n",
1010                         __func__, q_id, current->pid, vma->vm_start,
1011                         phys_off, (unsigned long)sz);
1012
1013         if (sz != ublk_queue_cmd_buf_size(ub, q_id))
1014                 return -EINVAL;
1015
1016         pfn = virt_to_phys(ublk_queue_cmd_buf(ub, q_id)) >> PAGE_SHIFT;
1017         return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
1018 }
1019
1020 static void ublk_commit_completion(struct ublk_device *ub,
1021                 struct ublksrv_io_cmd *ub_cmd)
1022 {
1023         u32 qid = ub_cmd->q_id, tag = ub_cmd->tag;
1024         struct ublk_queue *ubq = ublk_get_queue(ub, qid);
1025         struct ublk_io *io = &ubq->ios[tag];
1026         struct request *req;
1027
1028         /* now this cmd slot is owned by nbd driver */
1029         io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
1030         io->res = ub_cmd->result;
1031
1032         /* find the io request and complete */
1033         req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
1034
1035         if (req && likely(!blk_should_fake_timeout(req->q)))
1036                 ublk_complete_rq(req);
1037 }
1038
1039 /*
1040  * When ->ubq_daemon is exiting, either new request is ended immediately,
1041  * or any queued io command is drained, so it is safe to abort queue
1042  * lockless
1043  */
1044 static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
1045 {
1046         int i;
1047
1048         if (!ublk_get_device(ub))
1049                 return;
1050
1051         for (i = 0; i < ubq->q_depth; i++) {
1052                 struct ublk_io *io = &ubq->ios[i];
1053
1054                 if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) {
1055                         struct request *rq;
1056
1057                         /*
1058                          * Either we fail the request or ublk_rq_task_work_fn
1059                          * will do it
1060                          */
1061                         rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);
1062                         if (rq)
1063                                 __ublk_fail_req(ubq, io, rq);
1064                 }
1065         }
1066         ublk_put_device(ub);
1067 }
1068
1069 static void ublk_daemon_monitor_work(struct work_struct *work)
1070 {
1071         struct ublk_device *ub =
1072                 container_of(work, struct ublk_device, monitor_work.work);
1073         int i;
1074
1075         for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {
1076                 struct ublk_queue *ubq = ublk_get_queue(ub, i);
1077
1078                 if (ubq_daemon_is_dying(ubq)) {
1079                         if (ublk_queue_can_use_recovery(ubq))
1080                                 schedule_work(&ub->quiesce_work);
1081                         else
1082                                 schedule_work(&ub->stop_work);
1083
1084                         /* abort queue is for making forward progress */
1085                         ublk_abort_queue(ub, ubq);
1086                 }
1087         }
1088
1089         /*
1090          * We can't schedule monitor work after ub's state is not UBLK_S_DEV_LIVE.
1091          * after ublk_remove() or __ublk_quiesce_dev() is started.
1092          *
1093          * No need ub->mutex, monitor work are canceled after state is marked
1094          * as not LIVE, so new state is observed reliably.
1095          */
1096         if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1097                 schedule_delayed_work(&ub->monitor_work,
1098                                 UBLK_DAEMON_MONITOR_PERIOD);
1099 }
1100
1101 static inline bool ublk_queue_ready(struct ublk_queue *ubq)
1102 {
1103         return ubq->nr_io_ready == ubq->q_depth;
1104 }
1105
1106 static void ublk_cancel_queue(struct ublk_queue *ubq)
1107 {
1108         int i;
1109
1110         if (!ublk_queue_ready(ubq))
1111                 return;
1112
1113         for (i = 0; i < ubq->q_depth; i++) {
1114                 struct ublk_io *io = &ubq->ios[i];
1115
1116                 if (io->flags & UBLK_IO_FLAG_ACTIVE)
1117                         io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0);
1118         }
1119
1120         /* all io commands are canceled */
1121         ubq->nr_io_ready = 0;
1122 }
1123
1124 /* Cancel all pending commands, must be called after del_gendisk() returns */
1125 static void ublk_cancel_dev(struct ublk_device *ub)
1126 {
1127         int i;
1128
1129         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1130                 ublk_cancel_queue(ublk_get_queue(ub, i));
1131 }
1132
1133 static bool ublk_check_inflight_rq(struct request *rq, void *data)
1134 {
1135         bool *idle = data;
1136
1137         if (blk_mq_request_started(rq)) {
1138                 *idle = false;
1139                 return false;
1140         }
1141         return true;
1142 }
1143
1144 static void ublk_wait_tagset_rqs_idle(struct ublk_device *ub)
1145 {
1146         bool idle;
1147
1148         WARN_ON_ONCE(!blk_queue_quiesced(ub->ub_disk->queue));
1149         while (true) {
1150                 idle = true;
1151                 blk_mq_tagset_busy_iter(&ub->tag_set,
1152                                 ublk_check_inflight_rq, &idle);
1153                 if (idle)
1154                         break;
1155                 msleep(UBLK_REQUEUE_DELAY_MS);
1156         }
1157 }
1158
1159 static void __ublk_quiesce_dev(struct ublk_device *ub)
1160 {
1161         pr_devel("%s: quiesce ub: dev_id %d state %s\n",
1162                         __func__, ub->dev_info.dev_id,
1163                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1164                         "LIVE" : "QUIESCED");
1165         blk_mq_quiesce_queue(ub->ub_disk->queue);
1166         ublk_wait_tagset_rqs_idle(ub);
1167         ub->dev_info.state = UBLK_S_DEV_QUIESCED;
1168         ublk_cancel_dev(ub);
1169         /* we are going to release task_struct of ubq_daemon and resets
1170          * ->ubq_daemon to NULL. So in monitor_work, check on ubq_daemon causes UAF.
1171          * Besides, monitor_work is not necessary in QUIESCED state since we have
1172          * already scheduled quiesce_work and quiesced all ubqs.
1173          *
1174          * Do not let monitor_work schedule itself if state it QUIESCED. And we cancel
1175          * it here and re-schedule it in END_USER_RECOVERY to avoid UAF.
1176          */
1177         cancel_delayed_work_sync(&ub->monitor_work);
1178 }
1179
1180 static void ublk_quiesce_work_fn(struct work_struct *work)
1181 {
1182         struct ublk_device *ub =
1183                 container_of(work, struct ublk_device, quiesce_work);
1184
1185         mutex_lock(&ub->mutex);
1186         if (ub->dev_info.state != UBLK_S_DEV_LIVE)
1187                 goto unlock;
1188         __ublk_quiesce_dev(ub);
1189  unlock:
1190         mutex_unlock(&ub->mutex);
1191 }
1192
1193 static void ublk_unquiesce_dev(struct ublk_device *ub)
1194 {
1195         int i;
1196
1197         pr_devel("%s: unquiesce ub: dev_id %d state %s\n",
1198                         __func__, ub->dev_info.dev_id,
1199                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1200                         "LIVE" : "QUIESCED");
1201         /* quiesce_work has run. We let requeued rqs be aborted
1202          * before running fallback_wq. "force_abort" must be seen
1203          * after request queue is unqiuesced. Then del_gendisk()
1204          * can move on.
1205          */
1206         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1207                 ublk_get_queue(ub, i)->force_abort = true;
1208
1209         blk_mq_unquiesce_queue(ub->ub_disk->queue);
1210         /* We may have requeued some rqs in ublk_quiesce_queue() */
1211         blk_mq_kick_requeue_list(ub->ub_disk->queue);
1212 }
1213
1214 static void ublk_stop_dev(struct ublk_device *ub)
1215 {
1216         mutex_lock(&ub->mutex);
1217         if (ub->dev_info.state == UBLK_S_DEV_DEAD)
1218                 goto unlock;
1219         if (ublk_can_use_recovery(ub)) {
1220                 if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1221                         __ublk_quiesce_dev(ub);
1222                 ublk_unquiesce_dev(ub);
1223         }
1224         del_gendisk(ub->ub_disk);
1225         ub->dev_info.state = UBLK_S_DEV_DEAD;
1226         ub->dev_info.ublksrv_pid = -1;
1227         put_disk(ub->ub_disk);
1228         ub->ub_disk = NULL;
1229  unlock:
1230         ublk_cancel_dev(ub);
1231         mutex_unlock(&ub->mutex);
1232         cancel_delayed_work_sync(&ub->monitor_work);
1233 }
1234
1235 /* device can only be started after all IOs are ready */
1236 static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
1237 {
1238         mutex_lock(&ub->mutex);
1239         ubq->nr_io_ready++;
1240         if (ublk_queue_ready(ubq)) {
1241                 ubq->ubq_daemon = current;
1242                 get_task_struct(ubq->ubq_daemon);
1243                 ub->nr_queues_ready++;
1244
1245                 if (capable(CAP_SYS_ADMIN))
1246                         ub->nr_privileged_daemon++;
1247         }
1248         if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
1249                 complete_all(&ub->completion);
1250         mutex_unlock(&ub->mutex);
1251 }
1252
1253 static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,
1254                 int tag)
1255 {
1256         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1257         struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag);
1258
1259         ublk_queue_cmd(ubq, req);
1260 }
1261
1262 static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
1263 {
1264         struct ublksrv_io_cmd *ub_cmd = (struct ublksrv_io_cmd *)cmd->cmd;
1265         struct ublk_device *ub = cmd->file->private_data;
1266         struct ublk_queue *ubq;
1267         struct ublk_io *io;
1268         u32 cmd_op = cmd->cmd_op;
1269         unsigned tag = ub_cmd->tag;
1270         int ret = -EINVAL;
1271         struct request *req;
1272
1273         pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
1274                         __func__, cmd->cmd_op, ub_cmd->q_id, tag,
1275                         ub_cmd->result);
1276
1277         if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues)
1278                 goto out;
1279
1280         ubq = ublk_get_queue(ub, ub_cmd->q_id);
1281         if (!ubq || ub_cmd->q_id != ubq->q_id)
1282                 goto out;
1283
1284         if (ubq->ubq_daemon && ubq->ubq_daemon != current)
1285                 goto out;
1286
1287         if (tag >= ubq->q_depth)
1288                 goto out;
1289
1290         io = &ubq->ios[tag];
1291
1292         /* there is pending io cmd, something must be wrong */
1293         if (io->flags & UBLK_IO_FLAG_ACTIVE) {
1294                 ret = -EBUSY;
1295                 goto out;
1296         }
1297
1298         /*
1299          * ensure that the user issues UBLK_IO_NEED_GET_DATA
1300          * iff the driver have set the UBLK_IO_FLAG_NEED_GET_DATA.
1301          */
1302         if ((!!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA))
1303                         ^ (cmd_op == UBLK_IO_NEED_GET_DATA))
1304                 goto out;
1305
1306         switch (cmd_op) {
1307         case UBLK_IO_FETCH_REQ:
1308                 /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
1309                 if (ublk_queue_ready(ubq)) {
1310                         ret = -EBUSY;
1311                         goto out;
1312                 }
1313                 /*
1314                  * The io is being handled by server, so COMMIT_RQ is expected
1315                  * instead of FETCH_REQ
1316                  */
1317                 if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
1318                         goto out;
1319                 /* FETCH_RQ has to provide IO buffer if NEED GET DATA is not enabled */
1320                 if (!ub_cmd->addr && !ublk_need_get_data(ubq))
1321                         goto out;
1322                 io->cmd = cmd;
1323                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1324                 io->addr = ub_cmd->addr;
1325
1326                 ublk_mark_io_ready(ub, ubq);
1327                 break;
1328         case UBLK_IO_COMMIT_AND_FETCH_REQ:
1329                 req = blk_mq_tag_to_rq(ub->tag_set.tags[ub_cmd->q_id], tag);
1330                 /*
1331                  * COMMIT_AND_FETCH_REQ has to provide IO buffer if NEED GET DATA is
1332                  * not enabled or it is Read IO.
1333                  */
1334                 if (!ub_cmd->addr && (!ublk_need_get_data(ubq) || req_op(req) == REQ_OP_READ))
1335                         goto out;
1336                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1337                         goto out;
1338                 io->addr = ub_cmd->addr;
1339                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1340                 io->cmd = cmd;
1341                 ublk_commit_completion(ub, ub_cmd);
1342                 break;
1343         case UBLK_IO_NEED_GET_DATA:
1344                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1345                         goto out;
1346                 io->addr = ub_cmd->addr;
1347                 io->cmd = cmd;
1348                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1349                 ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag);
1350                 break;
1351         default:
1352                 goto out;
1353         }
1354         return -EIOCBQUEUED;
1355
1356  out:
1357         io_uring_cmd_done(cmd, ret, 0);
1358         pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n",
1359                         __func__, cmd_op, tag, ret, io->flags);
1360         return -EIOCBQUEUED;
1361 }
1362
1363 static const struct file_operations ublk_ch_fops = {
1364         .owner = THIS_MODULE,
1365         .open = ublk_ch_open,
1366         .release = ublk_ch_release,
1367         .llseek = no_llseek,
1368         .uring_cmd = ublk_ch_uring_cmd,
1369         .mmap = ublk_ch_mmap,
1370 };
1371
1372 static void ublk_deinit_queue(struct ublk_device *ub, int q_id)
1373 {
1374         int size = ublk_queue_cmd_buf_size(ub, q_id);
1375         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1376
1377         if (ubq->ubq_daemon)
1378                 put_task_struct(ubq->ubq_daemon);
1379         if (ubq->io_cmd_buf)
1380                 free_pages((unsigned long)ubq->io_cmd_buf, get_order(size));
1381 }
1382
1383 static int ublk_init_queue(struct ublk_device *ub, int q_id)
1384 {
1385         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1386         gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO;
1387         void *ptr;
1388         int size;
1389
1390         ubq->flags = ub->dev_info.flags;
1391         ubq->q_id = q_id;
1392         ubq->q_depth = ub->dev_info.queue_depth;
1393         size = ublk_queue_cmd_buf_size(ub, q_id);
1394
1395         ptr = (void *) __get_free_pages(gfp_flags, get_order(size));
1396         if (!ptr)
1397                 return -ENOMEM;
1398
1399         ubq->io_cmd_buf = ptr;
1400         ubq->dev = ub;
1401         return 0;
1402 }
1403
1404 static void ublk_deinit_queues(struct ublk_device *ub)
1405 {
1406         int nr_queues = ub->dev_info.nr_hw_queues;
1407         int i;
1408
1409         if (!ub->__queues)
1410                 return;
1411
1412         for (i = 0; i < nr_queues; i++)
1413                 ublk_deinit_queue(ub, i);
1414         kfree(ub->__queues);
1415 }
1416
1417 static int ublk_init_queues(struct ublk_device *ub)
1418 {
1419         int nr_queues = ub->dev_info.nr_hw_queues;
1420         int depth = ub->dev_info.queue_depth;
1421         int ubq_size = sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io);
1422         int i, ret = -ENOMEM;
1423
1424         ub->queue_size = ubq_size;
1425         ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL);
1426         if (!ub->__queues)
1427                 return ret;
1428
1429         for (i = 0; i < nr_queues; i++) {
1430                 if (ublk_init_queue(ub, i))
1431                         goto fail;
1432         }
1433
1434         init_completion(&ub->completion);
1435         return 0;
1436
1437  fail:
1438         ublk_deinit_queues(ub);
1439         return ret;
1440 }
1441
1442 static int ublk_alloc_dev_number(struct ublk_device *ub, int idx)
1443 {
1444         int i = idx;
1445         int err;
1446
1447         spin_lock(&ublk_idr_lock);
1448         /* allocate id, if @id >= 0, we're requesting that specific id */
1449         if (i >= 0) {
1450                 err = idr_alloc(&ublk_index_idr, ub, i, i + 1, GFP_NOWAIT);
1451                 if (err == -ENOSPC)
1452                         err = -EEXIST;
1453         } else {
1454                 err = idr_alloc(&ublk_index_idr, ub, 0, 0, GFP_NOWAIT);
1455         }
1456         spin_unlock(&ublk_idr_lock);
1457
1458         if (err >= 0)
1459                 ub->ub_number = err;
1460
1461         return err;
1462 }
1463
1464 static void ublk_free_dev_number(struct ublk_device *ub)
1465 {
1466         spin_lock(&ublk_idr_lock);
1467         idr_remove(&ublk_index_idr, ub->ub_number);
1468         wake_up_all(&ublk_idr_wq);
1469         spin_unlock(&ublk_idr_lock);
1470 }
1471
1472 static void ublk_cdev_rel(struct device *dev)
1473 {
1474         struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev);
1475
1476         blk_mq_free_tag_set(&ub->tag_set);
1477         ublk_deinit_queues(ub);
1478         ublk_free_dev_number(ub);
1479         mutex_destroy(&ub->mutex);
1480         kfree(ub);
1481 }
1482
1483 static int ublk_add_chdev(struct ublk_device *ub)
1484 {
1485         struct device *dev = &ub->cdev_dev;
1486         int minor = ub->ub_number;
1487         int ret;
1488
1489         dev->parent = ublk_misc.this_device;
1490         dev->devt = MKDEV(MAJOR(ublk_chr_devt), minor);
1491         dev->class = ublk_chr_class;
1492         dev->release = ublk_cdev_rel;
1493         device_initialize(dev);
1494
1495         ret = dev_set_name(dev, "ublkc%d", minor);
1496         if (ret)
1497                 goto fail;
1498
1499         cdev_init(&ub->cdev, &ublk_ch_fops);
1500         ret = cdev_device_add(&ub->cdev, dev);
1501         if (ret)
1502                 goto fail;
1503
1504         ublks_added++;
1505         return 0;
1506  fail:
1507         put_device(dev);
1508         return ret;
1509 }
1510
1511 static void ublk_stop_work_fn(struct work_struct *work)
1512 {
1513         struct ublk_device *ub =
1514                 container_of(work, struct ublk_device, stop_work);
1515
1516         ublk_stop_dev(ub);
1517 }
1518
1519 /* align max io buffer size with PAGE_SIZE */
1520 static void ublk_align_max_io_size(struct ublk_device *ub)
1521 {
1522         unsigned int max_io_bytes = ub->dev_info.max_io_buf_bytes;
1523
1524         ub->dev_info.max_io_buf_bytes =
1525                 round_down(max_io_bytes, PAGE_SIZE);
1526 }
1527
1528 static int ublk_add_tag_set(struct ublk_device *ub)
1529 {
1530         ub->tag_set.ops = &ublk_mq_ops;
1531         ub->tag_set.nr_hw_queues = ub->dev_info.nr_hw_queues;
1532         ub->tag_set.queue_depth = ub->dev_info.queue_depth;
1533         ub->tag_set.numa_node = NUMA_NO_NODE;
1534         ub->tag_set.cmd_size = sizeof(struct ublk_rq_data);
1535         ub->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1536         ub->tag_set.driver_data = ub;
1537         return blk_mq_alloc_tag_set(&ub->tag_set);
1538 }
1539
1540 static void ublk_remove(struct ublk_device *ub)
1541 {
1542         ublk_stop_dev(ub);
1543         cancel_work_sync(&ub->stop_work);
1544         cancel_work_sync(&ub->quiesce_work);
1545         cdev_device_del(&ub->cdev, &ub->cdev_dev);
1546         put_device(&ub->cdev_dev);
1547         ublks_added--;
1548 }
1549
1550 static struct ublk_device *ublk_get_device_from_id(int idx)
1551 {
1552         struct ublk_device *ub = NULL;
1553
1554         if (idx < 0)
1555                 return NULL;
1556
1557         spin_lock(&ublk_idr_lock);
1558         ub = idr_find(&ublk_index_idr, idx);
1559         if (ub)
1560                 ub = ublk_get_device(ub);
1561         spin_unlock(&ublk_idr_lock);
1562
1563         return ub;
1564 }
1565
1566 static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
1567 {
1568         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1569         int ublksrv_pid = (int)header->data[0];
1570         struct gendisk *disk;
1571         int ret = -EINVAL;
1572
1573         if (ublksrv_pid <= 0)
1574                 return -EINVAL;
1575
1576         wait_for_completion_interruptible(&ub->completion);
1577
1578         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
1579
1580         mutex_lock(&ub->mutex);
1581         if (ub->dev_info.state == UBLK_S_DEV_LIVE ||
1582             test_bit(UB_STATE_USED, &ub->state)) {
1583                 ret = -EEXIST;
1584                 goto out_unlock;
1585         }
1586
1587         disk = blk_mq_alloc_disk(&ub->tag_set, NULL);
1588         if (IS_ERR(disk)) {
1589                 ret = PTR_ERR(disk);
1590                 goto out_unlock;
1591         }
1592         sprintf(disk->disk_name, "ublkb%d", ub->ub_number);
1593         disk->fops = &ub_fops;
1594         disk->private_data = ub;
1595
1596         ub->dev_info.ublksrv_pid = ublksrv_pid;
1597         ub->ub_disk = disk;
1598
1599         ret = ublk_apply_params(ub);
1600         if (ret)
1601                 goto out_put_disk;
1602
1603         /* don't probe partitions if any one ubq daemon is un-trusted */
1604         if (ub->nr_privileged_daemon != ub->nr_queues_ready)
1605                 set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
1606
1607         get_device(&ub->cdev_dev);
1608         ret = add_disk(disk);
1609         if (ret) {
1610                 /*
1611                  * Has to drop the reference since ->free_disk won't be
1612                  * called in case of add_disk failure.
1613                  */
1614                 ublk_put_device(ub);
1615                 goto out_put_disk;
1616         }
1617         set_bit(UB_STATE_USED, &ub->state);
1618         ub->dev_info.state = UBLK_S_DEV_LIVE;
1619 out_put_disk:
1620         if (ret)
1621                 put_disk(disk);
1622 out_unlock:
1623         mutex_unlock(&ub->mutex);
1624         return ret;
1625 }
1626
1627 static int ublk_ctrl_get_queue_affinity(struct ublk_device *ub,
1628                 struct io_uring_cmd *cmd)
1629 {
1630         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1631         void __user *argp = (void __user *)(unsigned long)header->addr;
1632         cpumask_var_t cpumask;
1633         unsigned long queue;
1634         unsigned int retlen;
1635         unsigned int i;
1636         int ret;
1637
1638         if (header->len * BITS_PER_BYTE < nr_cpu_ids)
1639                 return -EINVAL;
1640         if (header->len & (sizeof(unsigned long)-1))
1641                 return -EINVAL;
1642         if (!header->addr)
1643                 return -EINVAL;
1644
1645         queue = header->data[0];
1646         if (queue >= ub->dev_info.nr_hw_queues)
1647                 return -EINVAL;
1648
1649         if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
1650                 return -ENOMEM;
1651
1652         for_each_possible_cpu(i) {
1653                 if (ub->tag_set.map[HCTX_TYPE_DEFAULT].mq_map[i] == queue)
1654                         cpumask_set_cpu(i, cpumask);
1655         }
1656
1657         ret = -EFAULT;
1658         retlen = min_t(unsigned short, header->len, cpumask_size());
1659         if (copy_to_user(argp, cpumask, retlen))
1660                 goto out_free_cpumask;
1661         if (retlen != header->len &&
1662             clear_user(argp + retlen, header->len - retlen))
1663                 goto out_free_cpumask;
1664
1665         ret = 0;
1666 out_free_cpumask:
1667         free_cpumask_var(cpumask);
1668         return ret;
1669 }
1670
1671 static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info)
1672 {
1673         pr_devel("%s: dev id %d flags %llx\n", __func__,
1674                         info->dev_id, info->flags);
1675         pr_devel("\t nr_hw_queues %d queue_depth %d\n",
1676                         info->nr_hw_queues, info->queue_depth);
1677 }
1678
1679 static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
1680 {
1681         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1682         void __user *argp = (void __user *)(unsigned long)header->addr;
1683         struct ublksrv_ctrl_dev_info info;
1684         struct ublk_device *ub;
1685         int ret = -EINVAL;
1686
1687         if (header->len < sizeof(info) || !header->addr)
1688                 return -EINVAL;
1689         if (header->queue_id != (u16)-1) {
1690                 pr_warn("%s: queue_id is wrong %x\n",
1691                         __func__, header->queue_id);
1692                 return -EINVAL;
1693         }
1694
1695         if (copy_from_user(&info, argp, sizeof(info)))
1696                 return -EFAULT;
1697
1698         if (capable(CAP_SYS_ADMIN))
1699                 info.flags &= ~UBLK_F_UNPRIVILEGED_DEV;
1700         else if (!(info.flags & UBLK_F_UNPRIVILEGED_DEV))
1701                 return -EPERM;
1702
1703         /* the created device is always owned by current user */
1704         ublk_store_owner_uid_gid(&info.owner_uid, &info.owner_gid);
1705
1706         if (header->dev_id != info.dev_id) {
1707                 pr_warn("%s: dev id not match %u %u\n",
1708                         __func__, header->dev_id, info.dev_id);
1709                 return -EINVAL;
1710         }
1711
1712         ublk_dump_dev_info(&info);
1713
1714         ret = mutex_lock_killable(&ublk_ctl_mutex);
1715         if (ret)
1716                 return ret;
1717
1718         ret = -EACCES;
1719         if (ublks_added >= ublks_max)
1720                 goto out_unlock;
1721
1722         ret = -ENOMEM;
1723         ub = kzalloc(sizeof(*ub), GFP_KERNEL);
1724         if (!ub)
1725                 goto out_unlock;
1726         mutex_init(&ub->mutex);
1727         spin_lock_init(&ub->mm_lock);
1728         INIT_WORK(&ub->quiesce_work, ublk_quiesce_work_fn);
1729         INIT_WORK(&ub->stop_work, ublk_stop_work_fn);
1730         INIT_DELAYED_WORK(&ub->monitor_work, ublk_daemon_monitor_work);
1731
1732         ret = ublk_alloc_dev_number(ub, header->dev_id);
1733         if (ret < 0)
1734                 goto out_free_ub;
1735
1736         memcpy(&ub->dev_info, &info, sizeof(info));
1737
1738         /* update device id */
1739         ub->dev_info.dev_id = ub->ub_number;
1740
1741         /*
1742          * 64bit flags will be copied back to userspace as feature
1743          * negotiation result, so have to clear flags which driver
1744          * doesn't support yet, then userspace can get correct flags
1745          * (features) to handle.
1746          */
1747         ub->dev_info.flags &= UBLK_F_ALL;
1748
1749         if (!IS_BUILTIN(CONFIG_BLK_DEV_UBLK))
1750                 ub->dev_info.flags |= UBLK_F_URING_CMD_COMP_IN_TASK;
1751
1752         /* We are not ready to support zero copy */
1753         ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
1754
1755         ub->dev_info.nr_hw_queues = min_t(unsigned int,
1756                         ub->dev_info.nr_hw_queues, nr_cpu_ids);
1757         ublk_align_max_io_size(ub);
1758
1759         ret = ublk_init_queues(ub);
1760         if (ret)
1761                 goto out_free_dev_number;
1762
1763         ret = ublk_add_tag_set(ub);
1764         if (ret)
1765                 goto out_deinit_queues;
1766
1767         ret = -EFAULT;
1768         if (copy_to_user(argp, &ub->dev_info, sizeof(info)))
1769                 goto out_free_tag_set;
1770
1771         /*
1772          * Add the char dev so that ublksrv daemon can be setup.
1773          * ublk_add_chdev() will cleanup everything if it fails.
1774          */
1775         ret = ublk_add_chdev(ub);
1776         goto out_unlock;
1777
1778 out_free_tag_set:
1779         blk_mq_free_tag_set(&ub->tag_set);
1780 out_deinit_queues:
1781         ublk_deinit_queues(ub);
1782 out_free_dev_number:
1783         ublk_free_dev_number(ub);
1784 out_free_ub:
1785         mutex_destroy(&ub->mutex);
1786         kfree(ub);
1787 out_unlock:
1788         mutex_unlock(&ublk_ctl_mutex);
1789         return ret;
1790 }
1791
1792 static inline bool ublk_idr_freed(int id)
1793 {
1794         void *ptr;
1795
1796         spin_lock(&ublk_idr_lock);
1797         ptr = idr_find(&ublk_index_idr, id);
1798         spin_unlock(&ublk_idr_lock);
1799
1800         return ptr == NULL;
1801 }
1802
1803 static int ublk_ctrl_del_dev(struct ublk_device **p_ub)
1804 {
1805         struct ublk_device *ub = *p_ub;
1806         int idx = ub->ub_number;
1807         int ret;
1808
1809         ret = mutex_lock_killable(&ublk_ctl_mutex);
1810         if (ret)
1811                 return ret;
1812
1813         if (!test_bit(UB_STATE_DELETED, &ub->state)) {
1814                 ublk_remove(ub);
1815                 set_bit(UB_STATE_DELETED, &ub->state);
1816         }
1817
1818         /* Mark the reference as consumed */
1819         *p_ub = NULL;
1820         ublk_put_device(ub);
1821         mutex_unlock(&ublk_ctl_mutex);
1822
1823         /*
1824          * Wait until the idr is removed, then it can be reused after
1825          * DEL_DEV command is returned.
1826          *
1827          * If we returns because of user interrupt, future delete command
1828          * may come:
1829          *
1830          * - the device number isn't freed, this device won't or needn't
1831          *   be deleted again, since UB_STATE_DELETED is set, and device
1832          *   will be released after the last reference is dropped
1833          *
1834          * - the device number is freed already, we will not find this
1835          *   device via ublk_get_device_from_id()
1836          */
1837         wait_event_interruptible(ublk_idr_wq, ublk_idr_freed(idx));
1838
1839         return 0;
1840 }
1841
1842 static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd)
1843 {
1844         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1845
1846         pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n",
1847                         __func__, cmd->cmd_op, header->dev_id, header->queue_id,
1848                         header->data[0], header->addr, header->len);
1849 }
1850
1851 static int ublk_ctrl_stop_dev(struct ublk_device *ub)
1852 {
1853         ublk_stop_dev(ub);
1854         cancel_work_sync(&ub->stop_work);
1855         cancel_work_sync(&ub->quiesce_work);
1856
1857         return 0;
1858 }
1859
1860 static int ublk_ctrl_get_dev_info(struct ublk_device *ub,
1861                 struct io_uring_cmd *cmd)
1862 {
1863         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1864         void __user *argp = (void __user *)(unsigned long)header->addr;
1865
1866         if (header->len < sizeof(struct ublksrv_ctrl_dev_info) || !header->addr)
1867                 return -EINVAL;
1868
1869         if (copy_to_user(argp, &ub->dev_info, sizeof(ub->dev_info)))
1870                 return -EFAULT;
1871
1872         return 0;
1873 }
1874
1875 /* TYPE_DEVT is readonly, so fill it up before returning to userspace */
1876 static void ublk_ctrl_fill_params_devt(struct ublk_device *ub)
1877 {
1878         ub->params.devt.char_major = MAJOR(ub->cdev_dev.devt);
1879         ub->params.devt.char_minor = MINOR(ub->cdev_dev.devt);
1880
1881         if (ub->ub_disk) {
1882                 ub->params.devt.disk_major = MAJOR(disk_devt(ub->ub_disk));
1883                 ub->params.devt.disk_minor = MINOR(disk_devt(ub->ub_disk));
1884         } else {
1885                 ub->params.devt.disk_major = 0;
1886                 ub->params.devt.disk_minor = 0;
1887         }
1888         ub->params.types |= UBLK_PARAM_TYPE_DEVT;
1889 }
1890
1891 static int ublk_ctrl_get_params(struct ublk_device *ub,
1892                 struct io_uring_cmd *cmd)
1893 {
1894         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1895         void __user *argp = (void __user *)(unsigned long)header->addr;
1896         struct ublk_params_header ph;
1897         int ret;
1898
1899         if (header->len <= sizeof(ph) || !header->addr)
1900                 return -EINVAL;
1901
1902         if (copy_from_user(&ph, argp, sizeof(ph)))
1903                 return -EFAULT;
1904
1905         if (ph.len > header->len || !ph.len)
1906                 return -EINVAL;
1907
1908         if (ph.len > sizeof(struct ublk_params))
1909                 ph.len = sizeof(struct ublk_params);
1910
1911         mutex_lock(&ub->mutex);
1912         ublk_ctrl_fill_params_devt(ub);
1913         if (copy_to_user(argp, &ub->params, ph.len))
1914                 ret = -EFAULT;
1915         else
1916                 ret = 0;
1917         mutex_unlock(&ub->mutex);
1918
1919         return ret;
1920 }
1921
1922 static int ublk_ctrl_set_params(struct ublk_device *ub,
1923                 struct io_uring_cmd *cmd)
1924 {
1925         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1926         void __user *argp = (void __user *)(unsigned long)header->addr;
1927         struct ublk_params_header ph;
1928         int ret = -EFAULT;
1929
1930         if (header->len <= sizeof(ph) || !header->addr)
1931                 return -EINVAL;
1932
1933         if (copy_from_user(&ph, argp, sizeof(ph)))
1934                 return -EFAULT;
1935
1936         if (ph.len > header->len || !ph.len || !ph.types)
1937                 return -EINVAL;
1938
1939         if (ph.len > sizeof(struct ublk_params))
1940                 ph.len = sizeof(struct ublk_params);
1941
1942         /* parameters can only be changed when device isn't live */
1943         mutex_lock(&ub->mutex);
1944         if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
1945                 ret = -EACCES;
1946         } else if (copy_from_user(&ub->params, argp, ph.len)) {
1947                 ret = -EFAULT;
1948         } else {
1949                 /* clear all we don't support yet */
1950                 ub->params.types &= UBLK_PARAM_TYPE_ALL;
1951                 ret = ublk_validate_params(ub);
1952         }
1953         mutex_unlock(&ub->mutex);
1954
1955         return ret;
1956 }
1957
1958 static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
1959 {
1960         int i;
1961
1962         WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));
1963         /* All old ioucmds have to be completed */
1964         WARN_ON_ONCE(ubq->nr_io_ready);
1965         /* old daemon is PF_EXITING, put it now */
1966         put_task_struct(ubq->ubq_daemon);
1967         /* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */
1968         ubq->ubq_daemon = NULL;
1969
1970         for (i = 0; i < ubq->q_depth; i++) {
1971                 struct ublk_io *io = &ubq->ios[i];
1972
1973                 /* forget everything now and be ready for new FETCH_REQ */
1974                 io->flags = 0;
1975                 io->cmd = NULL;
1976                 io->addr = 0;
1977         }
1978 }
1979
1980 static int ublk_ctrl_start_recovery(struct ublk_device *ub,
1981                 struct io_uring_cmd *cmd)
1982 {
1983         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1984         int ret = -EINVAL;
1985         int i;
1986
1987         mutex_lock(&ub->mutex);
1988         if (!ublk_can_use_recovery(ub))
1989                 goto out_unlock;
1990         /*
1991          * START_RECOVERY is only allowd after:
1992          *
1993          * (1) UB_STATE_OPEN is not set, which means the dying process is exited
1994          *     and related io_uring ctx is freed so file struct of /dev/ublkcX is
1995          *     released.
1996          *
1997          * (2) UBLK_S_DEV_QUIESCED is set, which means the quiesce_work:
1998          *     (a)has quiesced request queue
1999          *     (b)has requeued every inflight rqs whose io_flags is ACTIVE
2000          *     (c)has requeued/aborted every inflight rqs whose io_flags is NOT ACTIVE
2001          *     (d)has completed/camceled all ioucmds owned by ther dying process
2002          */
2003         if (test_bit(UB_STATE_OPEN, &ub->state) ||
2004                         ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
2005                 ret = -EBUSY;
2006                 goto out_unlock;
2007         }
2008         pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id);
2009         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
2010                 ublk_queue_reinit(ub, ublk_get_queue(ub, i));
2011         /* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */
2012         ub->mm = NULL;
2013         ub->nr_queues_ready = 0;
2014         ub->nr_privileged_daemon = 0;
2015         init_completion(&ub->completion);
2016         ret = 0;
2017  out_unlock:
2018         mutex_unlock(&ub->mutex);
2019         return ret;
2020 }
2021
2022 static int ublk_ctrl_end_recovery(struct ublk_device *ub,
2023                 struct io_uring_cmd *cmd)
2024 {
2025         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
2026         int ublksrv_pid = (int)header->data[0];
2027         int ret = -EINVAL;
2028
2029         pr_devel("%s: Waiting for new ubq_daemons(nr: %d) are ready, dev id %d...\n",
2030                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
2031         /* wait until new ubq_daemon sending all FETCH_REQ */
2032         wait_for_completion_interruptible(&ub->completion);
2033         pr_devel("%s: All new ubq_daemons(nr: %d) are ready, dev id %d\n",
2034                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
2035
2036         mutex_lock(&ub->mutex);
2037         if (!ublk_can_use_recovery(ub))
2038                 goto out_unlock;
2039
2040         if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
2041                 ret = -EBUSY;
2042                 goto out_unlock;
2043         }
2044         ub->dev_info.ublksrv_pid = ublksrv_pid;
2045         pr_devel("%s: new ublksrv_pid %d, dev id %d\n",
2046                         __func__, ublksrv_pid, header->dev_id);
2047         blk_mq_unquiesce_queue(ub->ub_disk->queue);
2048         pr_devel("%s: queue unquiesced, dev id %d.\n",
2049                         __func__, header->dev_id);
2050         blk_mq_kick_requeue_list(ub->ub_disk->queue);
2051         ub->dev_info.state = UBLK_S_DEV_LIVE;
2052         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
2053         ret = 0;
2054  out_unlock:
2055         mutex_unlock(&ub->mutex);
2056         return ret;
2057 }
2058
2059 /*
2060  * All control commands are sent via /dev/ublk-control, so we have to check
2061  * the destination device's permission
2062  */
2063 static int ublk_char_dev_permission(struct ublk_device *ub,
2064                 const char *dev_path, int mask)
2065 {
2066         int err;
2067         struct path path;
2068         struct kstat stat;
2069
2070         err = kern_path(dev_path, LOOKUP_FOLLOW, &path);
2071         if (err)
2072                 return err;
2073
2074         err = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
2075         if (err)
2076                 goto exit;
2077
2078         err = -EPERM;
2079         if (stat.rdev != ub->cdev_dev.devt || !S_ISCHR(stat.mode))
2080                 goto exit;
2081
2082         err = inode_permission(&nop_mnt_idmap,
2083                         d_backing_inode(path.dentry), mask);
2084 exit:
2085         path_put(&path);
2086         return err;
2087 }
2088
2089 static int ublk_ctrl_uring_cmd_permission(struct ublk_device *ub,
2090                 struct io_uring_cmd *cmd)
2091 {
2092         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
2093         bool unprivileged = ub->dev_info.flags & UBLK_F_UNPRIVILEGED_DEV;
2094         void __user *argp = (void __user *)(unsigned long)header->addr;
2095         char *dev_path = NULL;
2096         int ret = 0;
2097         int mask;
2098
2099         if (!unprivileged) {
2100                 if (!capable(CAP_SYS_ADMIN))
2101                         return -EPERM;
2102                 /*
2103                  * The new added command of UBLK_CMD_GET_DEV_INFO2 includes
2104                  * char_dev_path in payload too, since userspace may not
2105                  * know if the specified device is created as unprivileged
2106                  * mode.
2107                  */
2108                 if (cmd->cmd_op != UBLK_CMD_GET_DEV_INFO2)
2109                         return 0;
2110         }
2111
2112         /*
2113          * User has to provide the char device path for unprivileged ublk
2114          *
2115          * header->addr always points to the dev path buffer, and
2116          * header->dev_path_len records length of dev path buffer.
2117          */
2118         if (!header->dev_path_len || header->dev_path_len > PATH_MAX)
2119                 return -EINVAL;
2120
2121         if (header->len < header->dev_path_len)
2122                 return -EINVAL;
2123
2124         dev_path = kmalloc(header->dev_path_len + 1, GFP_KERNEL);
2125         if (!dev_path)
2126                 return -ENOMEM;
2127
2128         ret = -EFAULT;
2129         if (copy_from_user(dev_path, argp, header->dev_path_len))
2130                 goto exit;
2131         dev_path[header->dev_path_len] = 0;
2132
2133         ret = -EINVAL;
2134         switch (cmd->cmd_op) {
2135         case UBLK_CMD_GET_DEV_INFO:
2136         case UBLK_CMD_GET_DEV_INFO2:
2137         case UBLK_CMD_GET_QUEUE_AFFINITY:
2138         case UBLK_CMD_GET_PARAMS:
2139                 mask = MAY_READ;
2140                 break;
2141         case UBLK_CMD_START_DEV:
2142         case UBLK_CMD_STOP_DEV:
2143         case UBLK_CMD_ADD_DEV:
2144         case UBLK_CMD_DEL_DEV:
2145         case UBLK_CMD_SET_PARAMS:
2146         case UBLK_CMD_START_USER_RECOVERY:
2147         case UBLK_CMD_END_USER_RECOVERY:
2148                 mask = MAY_READ | MAY_WRITE;
2149                 break;
2150         default:
2151                 goto exit;
2152         }
2153
2154         ret = ublk_char_dev_permission(ub, dev_path, mask);
2155         if (!ret) {
2156                 header->len -= header->dev_path_len;
2157                 header->addr += header->dev_path_len;
2158         }
2159         pr_devel("%s: dev id %d cmd_op %x uid %d gid %d path %s ret %d\n",
2160                         __func__, ub->ub_number, cmd->cmd_op,
2161                         ub->dev_info.owner_uid, ub->dev_info.owner_gid,
2162                         dev_path, ret);
2163 exit:
2164         kfree(dev_path);
2165         return ret;
2166 }
2167
2168 static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
2169                 unsigned int issue_flags)
2170 {
2171         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
2172         struct ublk_device *ub = NULL;
2173         int ret = -EINVAL;
2174
2175         if (issue_flags & IO_URING_F_NONBLOCK)
2176                 return -EAGAIN;
2177
2178         ublk_ctrl_cmd_dump(cmd);
2179
2180         if (!(issue_flags & IO_URING_F_SQE128))
2181                 goto out;
2182
2183         if (cmd->cmd_op != UBLK_CMD_ADD_DEV) {
2184                 ret = -ENODEV;
2185                 ub = ublk_get_device_from_id(header->dev_id);
2186                 if (!ub)
2187                         goto out;
2188
2189                 ret = ublk_ctrl_uring_cmd_permission(ub, cmd);
2190         } else {
2191                 /* ADD_DEV permission check is done in command handler */
2192                 ret = 0;
2193         }
2194
2195         if (ret)
2196                 goto put_dev;
2197
2198         switch (cmd->cmd_op) {
2199         case UBLK_CMD_START_DEV:
2200                 ret = ublk_ctrl_start_dev(ub, cmd);
2201                 break;
2202         case UBLK_CMD_STOP_DEV:
2203                 ret = ublk_ctrl_stop_dev(ub);
2204                 break;
2205         case UBLK_CMD_GET_DEV_INFO:
2206         case UBLK_CMD_GET_DEV_INFO2:
2207                 ret = ublk_ctrl_get_dev_info(ub, cmd);
2208                 break;
2209         case UBLK_CMD_ADD_DEV:
2210                 ret = ublk_ctrl_add_dev(cmd);
2211                 break;
2212         case UBLK_CMD_DEL_DEV:
2213                 ret = ublk_ctrl_del_dev(&ub);
2214                 break;
2215         case UBLK_CMD_GET_QUEUE_AFFINITY:
2216                 ret = ublk_ctrl_get_queue_affinity(ub, cmd);
2217                 break;
2218         case UBLK_CMD_GET_PARAMS:
2219                 ret = ublk_ctrl_get_params(ub, cmd);
2220                 break;
2221         case UBLK_CMD_SET_PARAMS:
2222                 ret = ublk_ctrl_set_params(ub, cmd);
2223                 break;
2224         case UBLK_CMD_START_USER_RECOVERY:
2225                 ret = ublk_ctrl_start_recovery(ub, cmd);
2226                 break;
2227         case UBLK_CMD_END_USER_RECOVERY:
2228                 ret = ublk_ctrl_end_recovery(ub, cmd);
2229                 break;
2230         default:
2231                 ret = -ENOTSUPP;
2232                 break;
2233         }
2234
2235  put_dev:
2236         if (ub)
2237                 ublk_put_device(ub);
2238  out:
2239         io_uring_cmd_done(cmd, ret, 0);
2240         pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n",
2241                         __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id);
2242         return -EIOCBQUEUED;
2243 }
2244
2245 static const struct file_operations ublk_ctl_fops = {
2246         .open           = nonseekable_open,
2247         .uring_cmd      = ublk_ctrl_uring_cmd,
2248         .owner          = THIS_MODULE,
2249         .llseek         = noop_llseek,
2250 };
2251
2252 static struct miscdevice ublk_misc = {
2253         .minor          = MISC_DYNAMIC_MINOR,
2254         .name           = "ublk-control",
2255         .fops           = &ublk_ctl_fops,
2256 };
2257
2258 static int __init ublk_init(void)
2259 {
2260         int ret;
2261
2262         init_waitqueue_head(&ublk_idr_wq);
2263
2264         ret = misc_register(&ublk_misc);
2265         if (ret)
2266                 return ret;
2267
2268         ret = alloc_chrdev_region(&ublk_chr_devt, 0, UBLK_MINORS, "ublk-char");
2269         if (ret)
2270                 goto unregister_mis;
2271
2272         ublk_chr_class = class_create(THIS_MODULE, "ublk-char");
2273         if (IS_ERR(ublk_chr_class)) {
2274                 ret = PTR_ERR(ublk_chr_class);
2275                 goto free_chrdev_region;
2276         }
2277         return 0;
2278
2279 free_chrdev_region:
2280         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2281 unregister_mis:
2282         misc_deregister(&ublk_misc);
2283         return ret;
2284 }
2285
2286 static void __exit ublk_exit(void)
2287 {
2288         struct ublk_device *ub;
2289         int id;
2290
2291         idr_for_each_entry(&ublk_index_idr, ub, id)
2292                 ublk_remove(ub);
2293
2294         class_destroy(ublk_chr_class);
2295         misc_deregister(&ublk_misc);
2296
2297         idr_destroy(&ublk_index_idr);
2298         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2299 }
2300
2301 module_init(ublk_init);
2302 module_exit(ublk_exit);
2303
2304 module_param(ublks_max, int, 0444);
2305 MODULE_PARM_DESC(ublks_max, "max number of ublk devices allowed to add(default: 64)");
2306
2307 MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>");
2308 MODULE_LICENSE("GPL");