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 <uapi/linux/ublk_cmd.h>
  46
  47 #define UBLK_MINORS             (1U << MINORBITS)
  48
  49 /* All UBLK_F_* have to be included into UBLK_F_ALL */
  50 #define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY \
  51                 | UBLK_F_URING_CMD_COMP_IN_TASK \
  52                 | UBLK_F_NEED_GET_DATA \
  53                 | UBLK_F_USER_RECOVERY \
  54                 | UBLK_F_USER_RECOVERY_REISSUE)
  55
  56 /* All UBLK_PARAM_TYPE_* should be included here */
  57 #define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD)
  58
  59 struct ublk_rq_data {
  60         struct llist_node node;
  61         struct callback_head work;
  62 };
  63
  64 struct ublk_uring_cmd_pdu {
  65         struct ublk_queue *ubq;
  66 };
  67
  68 /*
  69  * io command is active: sqe cmd is received, and its cqe isn't done
  70  *
  71  * If the flag is set, the io command is owned by ublk driver, and waited
  72  * for incoming blk-mq request from the ublk block device.
  73  *
  74  * If the flag is cleared, the io command will be completed, and owned by
  75  * ublk server.
  76  */
  77 #define UBLK_IO_FLAG_ACTIVE     0x01
  78
  79 /*
  80  * IO command is completed via cqe, and it is being handled by ublksrv, and
  81  * not committed yet
  82  *
  83  * Basically exclusively with UBLK_IO_FLAG_ACTIVE, so can be served for
  84  * cross verification
  85  */
  86 #define UBLK_IO_FLAG_OWNED_BY_SRV 0x02
  87
  88 /*
  89  * IO command is aborted, so this flag is set in case of
  90  * !UBLK_IO_FLAG_ACTIVE.
  91  *
  92  * After this flag is observed, any pending or new incoming request
  93  * associated with this io command will be failed immediately
  94  */
  95 #define UBLK_IO_FLAG_ABORTED 0x04
  96
  97 /*
  98  * UBLK_IO_FLAG_NEED_GET_DATA is set because IO command requires
  99  * get data buffer address from ublksrv.
 100  *
 101  * Then, bio data could be copied into this data buffer for a WRITE request
 102  * after the IO command is issued again and UBLK_IO_FLAG_NEED_GET_DATA is unset.
 103  */
 104 #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
 105
 106 struct ublk_io {
 107         /* userspace buffer address from io cmd */
 108         __u64   addr;
 109         unsigned int flags;
 110         int res;
 111
 112         struct io_uring_cmd *cmd;
 113 };
 114
 115 struct ublk_queue {
 116         int q_id;
 117         int q_depth;
 118
 119         unsigned long flags;
 120         struct task_struct      *ubq_daemon;
 121         char *io_cmd_buf;
 122
 123         struct llist_head       io_cmds;
 124
 125         unsigned long io_addr;  /* mapped vm address */
 126         unsigned int max_io_sz;
 127         bool force_abort;
 128         unsigned short nr_io_ready;     /* how many ios setup */
 129         struct ublk_device *dev;
 130         struct ublk_io ios[];
 131 };
 132
 133 #define UBLK_DAEMON_MONITOR_PERIOD      (5 * HZ)
 134
 135 struct ublk_device {
 136         struct gendisk          *ub_disk;
 137
 138         char    *__queues;
 139
 140         unsigned short  queue_size;
 141         struct ublksrv_ctrl_dev_info    dev_info;
 142
 143         struct blk_mq_tag_set   tag_set;
 144
 145         struct cdev             cdev;
 146         struct device           cdev_dev;
 147
 148 #define UB_STATE_OPEN           0
 149 #define UB_STATE_USED           1
 150         unsigned long           state;
 151         int                     ub_number;
 152
 153         struct mutex            mutex;
 154
 155         spinlock_t              mm_lock;
 156         struct mm_struct        *mm;
 157
 158         struct ublk_params      params;
 159
 160         struct completion       completion;
 161         unsigned int            nr_queues_ready;
 162         atomic_t                nr_aborted_queues;
 163
 164         /*
 165          * Our ubq->daemon may be killed without any notification, so
 166          * monitor each queue's daemon periodically
 167          */
 168         struct delayed_work     monitor_work;
 169         struct work_struct      quiesce_work;
 170         struct work_struct      stop_work;
 171 };
 172
 173 /* header of ublk_params */
 174 struct ublk_params_header {
 175         __u32   len;
 176         __u32   types;
 177 };
 178
 179 static dev_t ublk_chr_devt;
 180 static struct class *ublk_chr_class;
 181
 182 static DEFINE_IDR(ublk_index_idr);
 183 static DEFINE_SPINLOCK(ublk_idr_lock);
 184 static wait_queue_head_t ublk_idr_wq;   /* wait until one idr is freed */
 185
 186 static DEFINE_MUTEX(ublk_ctl_mutex);
 187
 188 static struct miscdevice ublk_misc;
 189
 190 static void ublk_dev_param_basic_apply(struct ublk_device *ub)
 191 {
 192         struct request_queue *q = ub->ub_disk->queue;
 193         const struct ublk_param_basic *p = &ub->params.basic;
 194
 195         blk_queue_logical_block_size(q, 1 << p->logical_bs_shift);
 196         blk_queue_physical_block_size(q, 1 << p->physical_bs_shift);
 197         blk_queue_io_min(q, 1 << p->io_min_shift);
 198         blk_queue_io_opt(q, 1 << p->io_opt_shift);
 199
 200         blk_queue_write_cache(q, p->attrs & UBLK_ATTR_VOLATILE_CACHE,
 201                         p->attrs & UBLK_ATTR_FUA);
 202         if (p->attrs & UBLK_ATTR_ROTATIONAL)
 203                 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
 204         else
 205                 blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
 206
 207         blk_queue_max_hw_sectors(q, p->max_sectors);
 208         blk_queue_chunk_sectors(q, p->chunk_sectors);
 209         blk_queue_virt_boundary(q, p->virt_boundary_mask);
 210
 211         if (p->attrs & UBLK_ATTR_READ_ONLY)
 212                 set_disk_ro(ub->ub_disk, true);
 213
 214         set_capacity(ub->ub_disk, p->dev_sectors);
 215 }
 216
 217 static void ublk_dev_param_discard_apply(struct ublk_device *ub)
 218 {
 219         struct request_queue *q = ub->ub_disk->queue;
 220         const struct ublk_param_discard *p = &ub->params.discard;
 221
 222         q->limits.discard_alignment = p->discard_alignment;
 223         q->limits.discard_granularity = p->discard_granularity;
 224         blk_queue_max_discard_sectors(q, p->max_discard_sectors);
 225         blk_queue_max_write_zeroes_sectors(q,
 226                         p->max_write_zeroes_sectors);
 227         blk_queue_max_discard_segments(q, p->max_discard_segments);
 228 }
 229
 230 static int ublk_validate_params(const struct ublk_device *ub)
 231 {
 232         /* basic param is the only one which must be set */
 233         if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
 234                 const struct ublk_param_basic *p = &ub->params.basic;
 235
 236                 if (p->logical_bs_shift > PAGE_SHIFT)
 237                         return -EINVAL;
 238
 239                 if (p->logical_bs_shift > p->physical_bs_shift)
 240                         return -EINVAL;
 241
 242                 if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
 243                         return -EINVAL;
 244         } else
 245                 return -EINVAL;
 246
 247         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD) {
 248                 const struct ublk_param_discard *p = &ub->params.discard;
 249
 250                 /* So far, only support single segment discard */
 251                 if (p->max_discard_sectors && p->max_discard_segments != 1)
 252                         return -EINVAL;
 253
 254                 if (!p->discard_granularity)
 255                         return -EINVAL;
 256         }
 257
 258         return 0;
 259 }
 260
 261 static int ublk_apply_params(struct ublk_device *ub)
 262 {
 263         if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
 264                 return -EINVAL;
 265
 266         ublk_dev_param_basic_apply(ub);
 267
 268         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
 269                 ublk_dev_param_discard_apply(ub);
 270
 271         return 0;
 272 }
 273
 274 static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq)
 275 {
 276         if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) &&
 277                         !(ubq->flags & UBLK_F_URING_CMD_COMP_IN_TASK))
 278                 return true;
 279         return false;
 280 }
 281
 282 static inline bool ublk_need_get_data(const struct ublk_queue *ubq)
 283 {
 284         if (ubq->flags & UBLK_F_NEED_GET_DATA)
 285                 return true;
 286         return false;
 287 }
 288
 289 static struct ublk_device *ublk_get_device(struct ublk_device *ub)
 290 {
 291         if (kobject_get_unless_zero(&ub->cdev_dev.kobj))
 292                 return ub;
 293         return NULL;
 294 }
 295
 296 static void ublk_put_device(struct ublk_device *ub)
 297 {
 298         put_device(&ub->cdev_dev);
 299 }
 300
 301 static inline struct ublk_queue *ublk_get_queue(struct ublk_device *dev,
 302                 int qid)
 303 {
 304        return (struct ublk_queue *)&(dev->__queues[qid * dev->queue_size]);
 305 }
 306
 307 static inline bool ublk_rq_has_data(const struct request *rq)
 308 {
 309         return rq->bio && bio_has_data(rq->bio);
 310 }
 311
 312 static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq,
 313                 int tag)
 314 {
 315         return (struct ublksrv_io_desc *)
 316                 &(ubq->io_cmd_buf[tag * sizeof(struct ublksrv_io_desc)]);
 317 }
 318
 319 static inline char *ublk_queue_cmd_buf(struct ublk_device *ub, int q_id)
 320 {
 321         return ublk_get_queue(ub, q_id)->io_cmd_buf;
 322 }
 323
 324 static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
 325 {
 326         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 327
 328         return round_up(ubq->q_depth * sizeof(struct ublksrv_io_desc),
 329                         PAGE_SIZE);
 330 }
 331
 332 static inline bool ublk_queue_can_use_recovery_reissue(
 333                 struct ublk_queue *ubq)
 334 {
 335         if ((ubq->flags & UBLK_F_USER_RECOVERY) &&
 336                         (ubq->flags & UBLK_F_USER_RECOVERY_REISSUE))
 337                 return true;
 338         return false;
 339 }
 340
 341 static inline bool ublk_queue_can_use_recovery(
 342                 struct ublk_queue *ubq)
 343 {
 344         if (ubq->flags & UBLK_F_USER_RECOVERY)
 345                 return true;
 346         return false;
 347 }
 348
 349 static inline bool ublk_can_use_recovery(struct ublk_device *ub)
 350 {
 351         if (ub->dev_info.flags & UBLK_F_USER_RECOVERY)
 352                 return true;
 353         return false;
 354 }
 355
 356 static void ublk_free_disk(struct gendisk *disk)
 357 {
 358         struct ublk_device *ub = disk->private_data;
 359
 360         clear_bit(UB_STATE_USED, &ub->state);
 361         put_device(&ub->cdev_dev);
 362 }
 363
 364 static const struct block_device_operations ub_fops = {
 365         .owner =        THIS_MODULE,
 366         .free_disk =    ublk_free_disk,
 367 };
 368
 369 #define UBLK_MAX_PIN_PAGES      32
 370
 371 struct ublk_map_data {
 372         const struct ublk_queue *ubq;
 373         const struct request *rq;
 374         const struct ublk_io *io;
 375         unsigned max_bytes;
 376 };
 377
 378 struct ublk_io_iter {
 379         struct page *pages[UBLK_MAX_PIN_PAGES];
 380         unsigned pg_off;        /* offset in the 1st page in pages */
 381         int nr_pages;           /* how many page pointers in pages */
 382         struct bio *bio;
 383         struct bvec_iter iter;
 384 };
 385
 386 static inline unsigned ublk_copy_io_pages(struct ublk_io_iter *data,
 387                 unsigned max_bytes, bool to_vm)
 388 {
 389         const unsigned total = min_t(unsigned, max_bytes,
 390                         PAGE_SIZE - data->pg_off +
 391                         ((data->nr_pages - 1) << PAGE_SHIFT));
 392         unsigned done = 0;
 393         unsigned pg_idx = 0;
 394
 395         while (done < total) {
 396                 struct bio_vec bv = bio_iter_iovec(data->bio, data->iter);
 397                 const unsigned int bytes = min3(bv.bv_len, total - done,
 398                                 (unsigned)(PAGE_SIZE - data->pg_off));
 399                 void *bv_buf = bvec_kmap_local(&bv);
 400                 void *pg_buf = kmap_local_page(data->pages[pg_idx]);
 401
 402                 if (to_vm)
 403                         memcpy(pg_buf + data->pg_off, bv_buf, bytes);
 404                 else
 405                         memcpy(bv_buf, pg_buf + data->pg_off, bytes);
 406
 407                 kunmap_local(pg_buf);
 408                 kunmap_local(bv_buf);
 409
 410                 /* advance page array */
 411                 data->pg_off += bytes;
 412                 if (data->pg_off == PAGE_SIZE) {
 413                         pg_idx += 1;
 414                         data->pg_off = 0;
 415                 }
 416
 417                 done += bytes;
 418
 419                 /* advance bio */
 420                 bio_advance_iter_single(data->bio, &data->iter, bytes);
 421                 if (!data->iter.bi_size) {
 422                         data->bio = data->bio->bi_next;
 423                         if (data->bio == NULL)
 424                                 break;
 425                         data->iter = data->bio->bi_iter;
 426                 }
 427         }
 428
 429         return done;
 430 }
 431
 432 static inline int ublk_copy_user_pages(struct ublk_map_data *data,
 433                 bool to_vm)
 434 {
 435         const unsigned int gup_flags = to_vm ? FOLL_WRITE : 0;
 436         const unsigned long start_vm = data->io->addr;
 437         unsigned int done = 0;
 438         struct ublk_io_iter iter = {
 439                 .pg_off = start_vm & (PAGE_SIZE - 1),
 440                 .bio    = data->rq->bio,
 441                 .iter   = data->rq->bio->bi_iter,
 442         };
 443         const unsigned int nr_pages = round_up(data->max_bytes +
 444                         (start_vm & (PAGE_SIZE - 1)), PAGE_SIZE) >> PAGE_SHIFT;
 445
 446         while (done < nr_pages) {
 447                 const unsigned to_pin = min_t(unsigned, UBLK_MAX_PIN_PAGES,
 448                                 nr_pages - done);
 449                 unsigned i, len;
 450
 451                 iter.nr_pages = get_user_pages_fast(start_vm +
 452                                 (done << PAGE_SHIFT), to_pin, gup_flags,
 453                                 iter.pages);
 454                 if (iter.nr_pages <= 0)
 455                         return done == 0 ? iter.nr_pages : done;
 456                 len = ublk_copy_io_pages(&iter, data->max_bytes, to_vm);
 457                 for (i = 0; i < iter.nr_pages; i++) {
 458                         if (to_vm)
 459                                 set_page_dirty(iter.pages[i]);
 460                         put_page(iter.pages[i]);
 461                 }
 462                 data->max_bytes -= len;
 463                 done += iter.nr_pages;
 464         }
 465
 466         return done;
 467 }
 468
 469 static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
 470                 struct ublk_io *io)
 471 {
 472         const unsigned int rq_bytes = blk_rq_bytes(req);
 473         /*
 474          * no zero copy, we delay copy WRITE request data into ublksrv
 475          * context and the big benefit is that pinning pages in current
 476          * context is pretty fast, see ublk_pin_user_pages
 477          */
 478         if (req_op(req) != REQ_OP_WRITE && req_op(req) != REQ_OP_FLUSH)
 479                 return rq_bytes;
 480
 481         if (ublk_rq_has_data(req)) {
 482                 struct ublk_map_data data = {
 483                         .ubq    =       ubq,
 484                         .rq     =       req,
 485                         .io     =       io,
 486                         .max_bytes =    rq_bytes,
 487                 };
 488
 489                 ublk_copy_user_pages(&data, true);
 490
 491                 return rq_bytes - data.max_bytes;
 492         }
 493         return rq_bytes;
 494 }
 495
 496 static int ublk_unmap_io(const struct ublk_queue *ubq,
 497                 const struct request *req,
 498                 struct ublk_io *io)
 499 {
 500         const unsigned int rq_bytes = blk_rq_bytes(req);
 501
 502         if (req_op(req) == REQ_OP_READ && ublk_rq_has_data(req)) {
 503                 struct ublk_map_data data = {
 504                         .ubq    =       ubq,
 505                         .rq     =       req,
 506                         .io     =       io,
 507                         .max_bytes =    io->res,
 508                 };
 509
 510                 WARN_ON_ONCE(io->res > rq_bytes);
 511
 512                 ublk_copy_user_pages(&data, false);
 513
 514                 return io->res - data.max_bytes;
 515         }
 516         return rq_bytes;
 517 }
 518
 519 static inline unsigned int ublk_req_build_flags(struct request *req)
 520 {
 521         unsigned flags = 0;
 522
 523         if (req->cmd_flags & REQ_FAILFAST_DEV)
 524                 flags |= UBLK_IO_F_FAILFAST_DEV;
 525
 526         if (req->cmd_flags & REQ_FAILFAST_TRANSPORT)
 527                 flags |= UBLK_IO_F_FAILFAST_TRANSPORT;
 528
 529         if (req->cmd_flags & REQ_FAILFAST_DRIVER)
 530                 flags |= UBLK_IO_F_FAILFAST_DRIVER;
 531
 532         if (req->cmd_flags & REQ_META)
 533                 flags |= UBLK_IO_F_META;
 534
 535         if (req->cmd_flags & REQ_FUA)
 536                 flags |= UBLK_IO_F_FUA;
 537
 538         if (req->cmd_flags & REQ_NOUNMAP)
 539                 flags |= UBLK_IO_F_NOUNMAP;
 540
 541         if (req->cmd_flags & REQ_SWAP)
 542                 flags |= UBLK_IO_F_SWAP;
 543
 544         return flags;
 545 }
 546
 547 static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 548 {
 549         struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
 550         struct ublk_io *io = &ubq->ios[req->tag];
 551         u32 ublk_op;
 552
 553         switch (req_op(req)) {
 554         case REQ_OP_READ:
 555                 ublk_op = UBLK_IO_OP_READ;
 556                 break;
 557         case REQ_OP_WRITE:
 558                 ublk_op = UBLK_IO_OP_WRITE;
 559                 break;
 560         case REQ_OP_FLUSH:
 561                 ublk_op = UBLK_IO_OP_FLUSH;
 562                 break;
 563         case REQ_OP_DISCARD:
 564                 ublk_op = UBLK_IO_OP_DISCARD;
 565                 break;
 566         case REQ_OP_WRITE_ZEROES:
 567                 ublk_op = UBLK_IO_OP_WRITE_ZEROES;
 568                 break;
 569         default:
 570                 return BLK_STS_IOERR;
 571         }
 572
 573         /* need to translate since kernel may change */
 574         iod->op_flags = ublk_op | ublk_req_build_flags(req);
 575         iod->nr_sectors = blk_rq_sectors(req);
 576         iod->start_sector = blk_rq_pos(req);
 577         iod->addr = io->addr;
 578
 579         return BLK_STS_OK;
 580 }
 581
 582 static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu(
 583                 struct io_uring_cmd *ioucmd)
 584 {
 585         return (struct ublk_uring_cmd_pdu *)&ioucmd->pdu;
 586 }
 587
 588 static inline bool ubq_daemon_is_dying(struct ublk_queue *ubq)
 589 {
 590         return ubq->ubq_daemon->flags & PF_EXITING;
 591 }
 592
 593 /* todo: handle partial completion */
 594 static void ublk_complete_rq(struct request *req)
 595 {
 596         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 597         struct ublk_io *io = &ubq->ios[req->tag];
 598         unsigned int unmapped_bytes;
 599
 600         /* failed read IO if nothing is read */
 601         if (!io->res && req_op(req) == REQ_OP_READ)
 602                 io->res = -EIO;
 603
 604         if (io->res < 0) {
 605                 blk_mq_end_request(req, errno_to_blk_status(io->res));
 606                 return;
 607         }
 608
 609         /*
 610          * FLUSH or DISCARD usually won't return bytes returned, so end them
 611          * directly.
 612          *
 613          * Both the two needn't unmap.
 614          */
 615         if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE) {
 616                 blk_mq_end_request(req, BLK_STS_OK);
 617                 return;
 618         }
 619
 620         /* for READ request, writing data in iod->addr to rq buffers */
 621         unmapped_bytes = ublk_unmap_io(ubq, req, io);
 622
 623         /*
 624          * Extremely impossible since we got data filled in just before
 625          *
 626          * Re-read simply for this unlikely case.
 627          */
 628         if (unlikely(unmapped_bytes < io->res))
 629                 io->res = unmapped_bytes;
 630
 631         if (blk_update_request(req, BLK_STS_OK, io->res))
 632                 blk_mq_requeue_request(req, true);
 633         else
 634                 __blk_mq_end_request(req, BLK_STS_OK);
 635 }
 636
 637 /*
 638  * Since __ublk_rq_task_work always fails requests immediately during
 639  * exiting, __ublk_fail_req() is only called from abort context during
 640  * exiting. So lock is unnecessary.
 641  *
 642  * Also aborting may not be started yet, keep in mind that one failed
 643  * request may be issued by block layer again.
 644  */
 645 static void __ublk_fail_req(struct ublk_queue *ubq, struct ublk_io *io,
 646                 struct request *req)
 647 {
 648         WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
 649
 650         if (!(io->flags & UBLK_IO_FLAG_ABORTED)) {
 651                 io->flags |= UBLK_IO_FLAG_ABORTED;
 652                 if (ublk_queue_can_use_recovery_reissue(ubq))
 653                         blk_mq_requeue_request(req, false);
 654                 else
 655                         blk_mq_end_request(req, BLK_STS_IOERR);
 656         }
 657 }
 658
 659 static void ubq_complete_io_cmd(struct ublk_io *io, int res)
 660 {
 661         /* mark this cmd owned by ublksrv */
 662         io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV;
 663
 664         /*
 665          * clear ACTIVE since we are done with this sqe/cmd slot
 666          * We can only accept io cmd in case of being not active.
 667          */
 668         io->flags &= ~UBLK_IO_FLAG_ACTIVE;
 669
 670         /* tell ublksrv one io request is coming */
 671         io_uring_cmd_done(io->cmd, res, 0);
 672 }
 673
 674 #define UBLK_REQUEUE_DELAY_MS   3
 675
 676 static inline void __ublk_abort_rq(struct ublk_queue *ubq,
 677                 struct request *rq)
 678 {
 679         /* We cannot process this rq so just requeue it. */
 680         if (ublk_queue_can_use_recovery(ubq))
 681                 blk_mq_requeue_request(rq, false);
 682         else
 683                 blk_mq_end_request(rq, BLK_STS_IOERR);
 684
 685         mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0);
 686 }
 687
 688 static inline void __ublk_rq_task_work(struct request *req)
 689 {
 690         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 691         int tag = req->tag;
 692         struct ublk_io *io = &ubq->ios[tag];
 693         unsigned int mapped_bytes;
 694
 695         pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",
 696                         __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 697                         ublk_get_iod(ubq, req->tag)->addr);
 698
 699         /*
 700          * Task is exiting if either:
 701          *
 702          * (1) current != ubq_daemon.
 703          * io_uring_cmd_complete_in_task() tries to run task_work
 704          * in a workqueue if ubq_daemon(cmd's task) is PF_EXITING.
 705          *
 706          * (2) current->flags & PF_EXITING.
 707          */
 708         if (unlikely(current != ubq->ubq_daemon || current->flags & PF_EXITING)) {
 709                 __ublk_abort_rq(ubq, req);
 710                 return;
 711         }
 712
 713         if (ublk_need_get_data(ubq) &&
 714                         (req_op(req) == REQ_OP_WRITE ||
 715                         req_op(req) == REQ_OP_FLUSH)) {
 716                 /*
 717                  * We have not handled UBLK_IO_NEED_GET_DATA command yet,
 718                  * so immepdately pass UBLK_IO_RES_NEED_GET_DATA to ublksrv
 719                  * and notify it.
 720                  */
 721                 if (!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA)) {
 722                         io->flags |= UBLK_IO_FLAG_NEED_GET_DATA;
 723                         pr_devel("%s: need get data. op %d, qid %d tag %d io_flags %x\n",
 724                                         __func__, io->cmd->cmd_op, ubq->q_id,
 725                                         req->tag, io->flags);
 726                         ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA);
 727                         return;
 728                 }
 729                 /*
 730                  * We have handled UBLK_IO_NEED_GET_DATA command,
 731                  * so clear UBLK_IO_FLAG_NEED_GET_DATA now and just
 732                  * do the copy work.
 733                  */
 734                 io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA;
 735                 /* update iod->addr because ublksrv may have passed a new io buffer */
 736                 ublk_get_iod(ubq, req->tag)->addr = io->addr;
 737                 pr_devel("%s: update iod->addr: op %d, qid %d tag %d io_flags %x addr %llx\n",
 738                                 __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 739                                 ublk_get_iod(ubq, req->tag)->addr);
 740         }
 741
 742         mapped_bytes = ublk_map_io(ubq, req, io);
 743
 744         /* partially mapped, update io descriptor */
 745         if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
 746                 /*
 747                  * Nothing mapped, retry until we succeed.
 748                  *
 749                  * We may never succeed in mapping any bytes here because
 750                  * of OOM. TODO: reserve one buffer with single page pinned
 751                  * for providing forward progress guarantee.
 752                  */
 753                 if (unlikely(!mapped_bytes)) {
 754                         blk_mq_requeue_request(req, false);
 755                         blk_mq_delay_kick_requeue_list(req->q,
 756                                         UBLK_REQUEUE_DELAY_MS);
 757                         return;
 758                 }
 759
 760                 ublk_get_iod(ubq, req->tag)->nr_sectors =
 761                         mapped_bytes >> 9;
 762         }
 763
 764         ubq_complete_io_cmd(io, UBLK_IO_RES_OK);
 765 }
 766
 767 static inline void ublk_forward_io_cmds(struct ublk_queue *ubq)
 768 {
 769         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
 770         struct ublk_rq_data *data, *tmp;
 771
 772         io_cmds = llist_reverse_order(io_cmds);
 773         llist_for_each_entry_safe(data, tmp, io_cmds, node)
 774                 __ublk_rq_task_work(blk_mq_rq_from_pdu(data));
 775 }
 776
 777 static inline void ublk_abort_io_cmds(struct ublk_queue *ubq)
 778 {
 779         struct llist_node *io_cmds = llist_del_all(&ubq->io_cmds);
 780         struct ublk_rq_data *data, *tmp;
 781
 782         llist_for_each_entry_safe(data, tmp, io_cmds, node)
 783                 __ublk_abort_rq(ubq, blk_mq_rq_from_pdu(data));
 784 }
 785
 786 static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd)
 787 {
 788         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 789         struct ublk_queue *ubq = pdu->ubq;
 790
 791         ublk_forward_io_cmds(ubq);
 792 }
 793
 794 static void ublk_rq_task_work_fn(struct callback_head *work)
 795 {
 796         struct ublk_rq_data *data = container_of(work,
 797                         struct ublk_rq_data, work);
 798         struct request *req = blk_mq_rq_from_pdu(data);
 799         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 800
 801         ublk_forward_io_cmds(ubq);
 802 }
 803
 804 static void ublk_queue_cmd(struct ublk_queue *ubq, struct request *rq)
 805 {
 806         struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
 807         struct ublk_io *io;
 808
 809         if (!llist_add(&data->node, &ubq->io_cmds))
 810                 return;
 811
 812         io = &ubq->ios[rq->tag];
 813         /*
 814          * If the check pass, we know that this is a re-issued request aborted
 815          * previously in monitor_work because the ubq_daemon(cmd's task) is
 816          * PF_EXITING. We cannot call io_uring_cmd_complete_in_task() anymore
 817          * because this ioucmd's io_uring context may be freed now if no inflight
 818          * ioucmd exists. Otherwise we may cause null-deref in ctx->fallback_work.
 819          *
 820          * Note: monitor_work sets UBLK_IO_FLAG_ABORTED and ends this request(releasing
 821          * the tag). Then the request is re-started(allocating the tag) and we are here.
 822          * Since releasing/allocating a tag implies smp_mb(), finding UBLK_IO_FLAG_ABORTED
 823          * guarantees that here is a re-issued request aborted previously.
 824          */
 825         if (unlikely(io->flags & UBLK_IO_FLAG_ABORTED)) {
 826                 ublk_abort_io_cmds(ubq);
 827         } else if (ublk_can_use_task_work(ubq)) {
 828                 if (task_work_add(ubq->ubq_daemon, &data->work,
 829                                         TWA_SIGNAL_NO_IPI))
 830                         ublk_abort_io_cmds(ubq);
 831         } else {
 832                 struct io_uring_cmd *cmd = io->cmd;
 833                 struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 834
 835                 pdu->ubq = ubq;
 836                 io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb);
 837         }
 838 }
 839
 840 static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
 841                 const struct blk_mq_queue_data *bd)
 842 {
 843         struct ublk_queue *ubq = hctx->driver_data;
 844         struct request *rq = bd->rq;
 845         blk_status_t res;
 846
 847         /* fill iod to slot in io cmd buffer */
 848         res = ublk_setup_iod(ubq, rq);
 849         if (unlikely(res != BLK_STS_OK))
 850                 return BLK_STS_IOERR;
 851
 852         /* With recovery feature enabled, force_abort is set in
 853          * ublk_stop_dev() before calling del_gendisk(). We have to
 854          * abort all requeued and new rqs here to let del_gendisk()
 855          * move on. Besides, we cannot not call io_uring_cmd_complete_in_task()
 856          * to avoid UAF on io_uring ctx.
 857          *
 858          * Note: force_abort is guaranteed to be seen because it is set
 859          * before request queue is unqiuesced.
 860          */
 861         if (ublk_queue_can_use_recovery(ubq) && unlikely(ubq->force_abort))
 862                 return BLK_STS_IOERR;
 863
 864         blk_mq_start_request(bd->rq);
 865
 866         if (unlikely(ubq_daemon_is_dying(ubq))) {
 867                 __ublk_abort_rq(ubq, rq);
 868                 return BLK_STS_OK;
 869         }
 870
 871         ublk_queue_cmd(ubq, rq);
 872
 873         return BLK_STS_OK;
 874 }
 875
 876 static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
 877                 unsigned int hctx_idx)
 878 {
 879         struct ublk_device *ub = driver_data;
 880         struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num);
 881
 882         hctx->driver_data = ubq;
 883         return 0;
 884 }
 885
 886 static int ublk_init_rq(struct blk_mq_tag_set *set, struct request *req,
 887                 unsigned int hctx_idx, unsigned int numa_node)
 888 {
 889         struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 890
 891         init_task_work(&data->work, ublk_rq_task_work_fn);
 892         return 0;
 893 }
 894
 895 static const struct blk_mq_ops ublk_mq_ops = {
 896         .queue_rq       = ublk_queue_rq,
 897         .init_hctx      = ublk_init_hctx,
 898         .init_request   = ublk_init_rq,
 899 };
 900
 901 static int ublk_ch_open(struct inode *inode, struct file *filp)
 902 {
 903         struct ublk_device *ub = container_of(inode->i_cdev,
 904                         struct ublk_device, cdev);
 905
 906         if (test_and_set_bit(UB_STATE_OPEN, &ub->state))
 907                 return -EBUSY;
 908         filp->private_data = ub;
 909         return 0;
 910 }
 911
 912 static int ublk_ch_release(struct inode *inode, struct file *filp)
 913 {
 914         struct ublk_device *ub = filp->private_data;
 915
 916         clear_bit(UB_STATE_OPEN, &ub->state);
 917         return 0;
 918 }
 919
 920 /* map pre-allocated per-queue cmd buffer to ublksrv daemon */
 921 static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
 922 {
 923         struct ublk_device *ub = filp->private_data;
 924         size_t sz = vma->vm_end - vma->vm_start;
 925         unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc);
 926         unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT;
 927         int q_id, ret = 0;
 928
 929         spin_lock(&ub->mm_lock);
 930         if (!ub->mm)
 931                 ub->mm = current->mm;
 932         if (current->mm != ub->mm)
 933                 ret = -EINVAL;
 934         spin_unlock(&ub->mm_lock);
 935
 936         if (ret)
 937                 return ret;
 938
 939         if (vma->vm_flags & VM_WRITE)
 940                 return -EPERM;
 941
 942         end = UBLKSRV_CMD_BUF_OFFSET + ub->dev_info.nr_hw_queues * max_sz;
 943         if (phys_off < UBLKSRV_CMD_BUF_OFFSET || phys_off >= end)
 944                 return -EINVAL;
 945
 946         q_id = (phys_off - UBLKSRV_CMD_BUF_OFFSET) / max_sz;
 947         pr_devel("%s: qid %d, pid %d, addr %lx pg_off %lx sz %lu\n",
 948                         __func__, q_id, current->pid, vma->vm_start,
 949                         phys_off, (unsigned long)sz);
 950
 951         if (sz != ublk_queue_cmd_buf_size(ub, q_id))
 952                 return -EINVAL;
 953
 954         pfn = virt_to_phys(ublk_queue_cmd_buf(ub, q_id)) >> PAGE_SHIFT;
 955         return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
 956 }
 957
 958 static void ublk_commit_completion(struct ublk_device *ub,
 959                 struct ublksrv_io_cmd *ub_cmd)
 960 {
 961         u32 qid = ub_cmd->q_id, tag = ub_cmd->tag;
 962         struct ublk_queue *ubq = ublk_get_queue(ub, qid);
 963         struct ublk_io *io = &ubq->ios[tag];
 964         struct request *req;
 965
 966         /* now this cmd slot is owned by nbd driver */
 967         io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
 968         io->res = ub_cmd->result;
 969
 970         /* find the io request and complete */
 971         req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
 972
 973         if (req && likely(!blk_should_fake_timeout(req->q)))
 974                 ublk_complete_rq(req);
 975 }
 976
 977 /*
 978  * When ->ubq_daemon is exiting, either new request is ended immediately,
 979  * or any queued io command is drained, so it is safe to abort queue
 980  * lockless
 981  */
 982 static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
 983 {
 984         int i;
 985
 986         if (!ublk_get_device(ub))
 987                 return;
 988
 989         for (i = 0; i < ubq->q_depth; i++) {
 990                 struct ublk_io *io = &ubq->ios[i];
 991
 992                 if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) {
 993                         struct request *rq;
 994
 995                         /*
 996                          * Either we fail the request or ublk_rq_task_work_fn
 997                          * will do it
 998                          */
 999                         rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);
1000                         if (rq)
1001                                 __ublk_fail_req(ubq, io, rq);
1002                 }
1003         }
1004         ublk_put_device(ub);
1005 }
1006
1007 static void ublk_daemon_monitor_work(struct work_struct *work)
1008 {
1009         struct ublk_device *ub =
1010                 container_of(work, struct ublk_device, monitor_work.work);
1011         int i;
1012
1013         for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {
1014                 struct ublk_queue *ubq = ublk_get_queue(ub, i);
1015
1016                 if (ubq_daemon_is_dying(ubq)) {
1017                         if (ublk_queue_can_use_recovery(ubq))
1018                                 schedule_work(&ub->quiesce_work);
1019                         else
1020                                 schedule_work(&ub->stop_work);
1021
1022                         /* abort queue is for making forward progress */
1023                         ublk_abort_queue(ub, ubq);
1024                 }
1025         }
1026
1027         /*
1028          * We can't schedule monitor work after ub's state is not UBLK_S_DEV_LIVE.
1029          * after ublk_remove() or __ublk_quiesce_dev() is started.
1030          *
1031          * No need ub->mutex, monitor work are canceled after state is marked
1032          * as not LIVE, so new state is observed reliably.
1033          */
1034         if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1035                 schedule_delayed_work(&ub->monitor_work,
1036                                 UBLK_DAEMON_MONITOR_PERIOD);
1037 }
1038
1039 static inline bool ublk_queue_ready(struct ublk_queue *ubq)
1040 {
1041         return ubq->nr_io_ready == ubq->q_depth;
1042 }
1043
1044 static void ublk_cancel_queue(struct ublk_queue *ubq)
1045 {
1046         int i;
1047
1048         if (!ublk_queue_ready(ubq))
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                         io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0);
1056         }
1057
1058         /* all io commands are canceled */
1059         ubq->nr_io_ready = 0;
1060 }
1061
1062 /* Cancel all pending commands, must be called after del_gendisk() returns */
1063 static void ublk_cancel_dev(struct ublk_device *ub)
1064 {
1065         int i;
1066
1067         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1068                 ublk_cancel_queue(ublk_get_queue(ub, i));
1069 }
1070
1071 static bool ublk_check_inflight_rq(struct request *rq, void *data)
1072 {
1073         bool *idle = data;
1074
1075         if (blk_mq_request_started(rq)) {
1076                 *idle = false;
1077                 return false;
1078         }
1079         return true;
1080 }
1081
1082 static void ublk_wait_tagset_rqs_idle(struct ublk_device *ub)
1083 {
1084         bool idle;
1085
1086         WARN_ON_ONCE(!blk_queue_quiesced(ub->ub_disk->queue));
1087         while (true) {
1088                 idle = true;
1089                 blk_mq_tagset_busy_iter(&ub->tag_set,
1090                                 ublk_check_inflight_rq, &idle);
1091                 if (idle)
1092                         break;
1093                 msleep(UBLK_REQUEUE_DELAY_MS);
1094         }
1095 }
1096
1097 static void __ublk_quiesce_dev(struct ublk_device *ub)
1098 {
1099         pr_devel("%s: quiesce ub: dev_id %d state %s\n",
1100                         __func__, ub->dev_info.dev_id,
1101                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1102                         "LIVE" : "QUIESCED");
1103         blk_mq_quiesce_queue(ub->ub_disk->queue);
1104         ublk_wait_tagset_rqs_idle(ub);
1105         ub->dev_info.state = UBLK_S_DEV_QUIESCED;
1106         ublk_cancel_dev(ub);
1107         /* we are going to release task_struct of ubq_daemon and resets
1108          * ->ubq_daemon to NULL. So in monitor_work, check on ubq_daemon causes UAF.
1109          * Besides, monitor_work is not necessary in QUIESCED state since we have
1110          * already scheduled quiesce_work and quiesced all ubqs.
1111          *
1112          * Do not let monitor_work schedule itself if state it QUIESCED. And we cancel
1113          * it here and re-schedule it in END_USER_RECOVERY to avoid UAF.
1114          */
1115         cancel_delayed_work_sync(&ub->monitor_work);
1116 }
1117
1118 static void ublk_quiesce_work_fn(struct work_struct *work)
1119 {
1120         struct ublk_device *ub =
1121                 container_of(work, struct ublk_device, quiesce_work);
1122
1123         mutex_lock(&ub->mutex);
1124         if (ub->dev_info.state != UBLK_S_DEV_LIVE)
1125                 goto unlock;
1126         __ublk_quiesce_dev(ub);
1127  unlock:
1128         mutex_unlock(&ub->mutex);
1129 }
1130
1131 static void ublk_unquiesce_dev(struct ublk_device *ub)
1132 {
1133         int i;
1134
1135         pr_devel("%s: unquiesce ub: dev_id %d state %s\n",
1136                         __func__, ub->dev_info.dev_id,
1137                         ub->dev_info.state == UBLK_S_DEV_LIVE ?
1138                         "LIVE" : "QUIESCED");
1139         /* quiesce_work has run. We let requeued rqs be aborted
1140          * before running fallback_wq. "force_abort" must be seen
1141          * after request queue is unqiuesced. Then del_gendisk()
1142          * can move on.
1143          */
1144         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1145                 ublk_get_queue(ub, i)->force_abort = true;
1146
1147         blk_mq_unquiesce_queue(ub->ub_disk->queue);
1148         /* We may have requeued some rqs in ublk_quiesce_queue() */
1149         blk_mq_kick_requeue_list(ub->ub_disk->queue);
1150 }
1151
1152 static void ublk_stop_dev(struct ublk_device *ub)
1153 {
1154         mutex_lock(&ub->mutex);
1155         if (ub->dev_info.state == UBLK_S_DEV_DEAD)
1156                 goto unlock;
1157         if (ublk_can_use_recovery(ub)) {
1158                 if (ub->dev_info.state == UBLK_S_DEV_LIVE)
1159                         __ublk_quiesce_dev(ub);
1160                 ublk_unquiesce_dev(ub);
1161         }
1162         del_gendisk(ub->ub_disk);
1163         ub->dev_info.state = UBLK_S_DEV_DEAD;
1164         ub->dev_info.ublksrv_pid = -1;
1165         put_disk(ub->ub_disk);
1166         ub->ub_disk = NULL;
1167  unlock:
1168         ublk_cancel_dev(ub);
1169         mutex_unlock(&ub->mutex);
1170         cancel_delayed_work_sync(&ub->monitor_work);
1171 }
1172
1173 /* device can only be started after all IOs are ready */
1174 static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
1175 {
1176         mutex_lock(&ub->mutex);
1177         ubq->nr_io_ready++;
1178         if (ublk_queue_ready(ubq)) {
1179                 ubq->ubq_daemon = current;
1180                 get_task_struct(ubq->ubq_daemon);
1181                 ub->nr_queues_ready++;
1182         }
1183         if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
1184                 complete_all(&ub->completion);
1185         mutex_unlock(&ub->mutex);
1186 }
1187
1188 static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,
1189                 int tag)
1190 {
1191         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1192         struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag);
1193
1194         ublk_queue_cmd(ubq, req);
1195 }
1196
1197 static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
1198 {
1199         struct ublksrv_io_cmd *ub_cmd = (struct ublksrv_io_cmd *)cmd->cmd;
1200         struct ublk_device *ub = cmd->file->private_data;
1201         struct ublk_queue *ubq;
1202         struct ublk_io *io;
1203         u32 cmd_op = cmd->cmd_op;
1204         unsigned tag = ub_cmd->tag;
1205         int ret = -EINVAL;
1206
1207         pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
1208                         __func__, cmd->cmd_op, ub_cmd->q_id, tag,
1209                         ub_cmd->result);
1210
1211         if (!(issue_flags & IO_URING_F_SQE128))
1212                 goto out;
1213
1214         if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues)
1215                 goto out;
1216
1217         ubq = ublk_get_queue(ub, ub_cmd->q_id);
1218         if (!ubq || ub_cmd->q_id != ubq->q_id)
1219                 goto out;
1220
1221         if (ubq->ubq_daemon && ubq->ubq_daemon != current)
1222                 goto out;
1223
1224         if (tag >= ubq->q_depth)
1225                 goto out;
1226
1227         io = &ubq->ios[tag];
1228
1229         /* there is pending io cmd, something must be wrong */
1230         if (io->flags & UBLK_IO_FLAG_ACTIVE) {
1231                 ret = -EBUSY;
1232                 goto out;
1233         }
1234
1235         /*
1236          * ensure that the user issues UBLK_IO_NEED_GET_DATA
1237          * iff the driver have set the UBLK_IO_FLAG_NEED_GET_DATA.
1238          */
1239         if ((!!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA))
1240                         ^ (cmd_op == UBLK_IO_NEED_GET_DATA))
1241                 goto out;
1242
1243         switch (cmd_op) {
1244         case UBLK_IO_FETCH_REQ:
1245                 /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
1246                 if (ublk_queue_ready(ubq)) {
1247                         ret = -EBUSY;
1248                         goto out;
1249                 }
1250                 /*
1251                  * The io is being handled by server, so COMMIT_RQ is expected
1252                  * instead of FETCH_REQ
1253                  */
1254                 if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
1255                         goto out;
1256                 /* FETCH_RQ has to provide IO buffer */
1257                 if (!ub_cmd->addr)
1258                         goto out;
1259                 io->cmd = cmd;
1260                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1261                 io->addr = ub_cmd->addr;
1262
1263                 ublk_mark_io_ready(ub, ubq);
1264                 break;
1265         case UBLK_IO_COMMIT_AND_FETCH_REQ:
1266                 /* FETCH_RQ has to provide IO buffer */
1267                 if (!ub_cmd->addr)
1268                         goto out;
1269                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1270                         goto out;
1271                 io->addr = ub_cmd->addr;
1272                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1273                 io->cmd = cmd;
1274                 ublk_commit_completion(ub, ub_cmd);
1275                 break;
1276         case UBLK_IO_NEED_GET_DATA:
1277                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1278                         goto out;
1279                 io->addr = ub_cmd->addr;
1280                 io->cmd = cmd;
1281                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1282                 ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag);
1283                 break;
1284         default:
1285                 goto out;
1286         }
1287         return -EIOCBQUEUED;
1288
1289  out:
1290         io_uring_cmd_done(cmd, ret, 0);
1291         pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n",
1292                         __func__, cmd_op, tag, ret, io->flags);
1293         return -EIOCBQUEUED;
1294 }
1295
1296 static const struct file_operations ublk_ch_fops = {
1297         .owner = THIS_MODULE,
1298         .open = ublk_ch_open,
1299         .release = ublk_ch_release,
1300         .llseek = no_llseek,
1301         .uring_cmd = ublk_ch_uring_cmd,
1302         .mmap = ublk_ch_mmap,
1303 };
1304
1305 static void ublk_deinit_queue(struct ublk_device *ub, int q_id)
1306 {
1307         int size = ublk_queue_cmd_buf_size(ub, q_id);
1308         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1309
1310         if (ubq->ubq_daemon)
1311                 put_task_struct(ubq->ubq_daemon);
1312         if (ubq->io_cmd_buf)
1313                 free_pages((unsigned long)ubq->io_cmd_buf, get_order(size));
1314 }
1315
1316 static int ublk_init_queue(struct ublk_device *ub, int q_id)
1317 {
1318         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1319         gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO;
1320         void *ptr;
1321         int size;
1322
1323         ubq->flags = ub->dev_info.flags;
1324         ubq->q_id = q_id;
1325         ubq->q_depth = ub->dev_info.queue_depth;
1326         size = ublk_queue_cmd_buf_size(ub, q_id);
1327
1328         ptr = (void *) __get_free_pages(gfp_flags, get_order(size));
1329         if (!ptr)
1330                 return -ENOMEM;
1331
1332         ubq->io_cmd_buf = ptr;
1333         ubq->dev = ub;
1334         return 0;
1335 }
1336
1337 static void ublk_deinit_queues(struct ublk_device *ub)
1338 {
1339         int nr_queues = ub->dev_info.nr_hw_queues;
1340         int i;
1341
1342         if (!ub->__queues)
1343                 return;
1344
1345         for (i = 0; i < nr_queues; i++)
1346                 ublk_deinit_queue(ub, i);
1347         kfree(ub->__queues);
1348 }
1349
1350 static int ublk_init_queues(struct ublk_device *ub)
1351 {
1352         int nr_queues = ub->dev_info.nr_hw_queues;
1353         int depth = ub->dev_info.queue_depth;
1354         int ubq_size = sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io);
1355         int i, ret = -ENOMEM;
1356
1357         ub->queue_size = ubq_size;
1358         ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL);
1359         if (!ub->__queues)
1360                 return ret;
1361
1362         for (i = 0; i < nr_queues; i++) {
1363                 if (ublk_init_queue(ub, i))
1364                         goto fail;
1365         }
1366
1367         init_completion(&ub->completion);
1368         return 0;
1369
1370  fail:
1371         ublk_deinit_queues(ub);
1372         return ret;
1373 }
1374
1375 static int ublk_alloc_dev_number(struct ublk_device *ub, int idx)
1376 {
1377         int i = idx;
1378         int err;
1379
1380         spin_lock(&ublk_idr_lock);
1381         /* allocate id, if @id >= 0, we're requesting that specific id */
1382         if (i >= 0) {
1383                 err = idr_alloc(&ublk_index_idr, ub, i, i + 1, GFP_NOWAIT);
1384                 if (err == -ENOSPC)
1385                         err = -EEXIST;
1386         } else {
1387                 err = idr_alloc(&ublk_index_idr, ub, 0, 0, GFP_NOWAIT);
1388         }
1389         spin_unlock(&ublk_idr_lock);
1390
1391         if (err >= 0)
1392                 ub->ub_number = err;
1393
1394         return err;
1395 }
1396
1397 static void ublk_free_dev_number(struct ublk_device *ub)
1398 {
1399         spin_lock(&ublk_idr_lock);
1400         idr_remove(&ublk_index_idr, ub->ub_number);
1401         wake_up_all(&ublk_idr_wq);
1402         spin_unlock(&ublk_idr_lock);
1403 }
1404
1405 static void ublk_cdev_rel(struct device *dev)
1406 {
1407         struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev);
1408
1409         blk_mq_free_tag_set(&ub->tag_set);
1410         ublk_deinit_queues(ub);
1411         ublk_free_dev_number(ub);
1412         mutex_destroy(&ub->mutex);
1413         kfree(ub);
1414 }
1415
1416 static int ublk_add_chdev(struct ublk_device *ub)
1417 {
1418         struct device *dev = &ub->cdev_dev;
1419         int minor = ub->ub_number;
1420         int ret;
1421
1422         dev->parent = ublk_misc.this_device;
1423         dev->devt = MKDEV(MAJOR(ublk_chr_devt), minor);
1424         dev->class = ublk_chr_class;
1425         dev->release = ublk_cdev_rel;
1426         device_initialize(dev);
1427
1428         ret = dev_set_name(dev, "ublkc%d", minor);
1429         if (ret)
1430                 goto fail;
1431
1432         cdev_init(&ub->cdev, &ublk_ch_fops);
1433         ret = cdev_device_add(&ub->cdev, dev);
1434         if (ret)
1435                 goto fail;
1436         return 0;
1437  fail:
1438         put_device(dev);
1439         return ret;
1440 }
1441
1442 static void ublk_stop_work_fn(struct work_struct *work)
1443 {
1444         struct ublk_device *ub =
1445                 container_of(work, struct ublk_device, stop_work);
1446
1447         ublk_stop_dev(ub);
1448 }
1449
1450 /* align max io buffer size with PAGE_SIZE */
1451 static void ublk_align_max_io_size(struct ublk_device *ub)
1452 {
1453         unsigned int max_io_bytes = ub->dev_info.max_io_buf_bytes;
1454
1455         ub->dev_info.max_io_buf_bytes =
1456                 round_down(max_io_bytes, PAGE_SIZE);
1457 }
1458
1459 static int ublk_add_tag_set(struct ublk_device *ub)
1460 {
1461         ub->tag_set.ops = &ublk_mq_ops;
1462         ub->tag_set.nr_hw_queues = ub->dev_info.nr_hw_queues;
1463         ub->tag_set.queue_depth = ub->dev_info.queue_depth;
1464         ub->tag_set.numa_node = NUMA_NO_NODE;
1465         ub->tag_set.cmd_size = sizeof(struct ublk_rq_data);
1466         ub->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1467         ub->tag_set.driver_data = ub;
1468         return blk_mq_alloc_tag_set(&ub->tag_set);
1469 }
1470
1471 static void ublk_remove(struct ublk_device *ub)
1472 {
1473         ublk_stop_dev(ub);
1474         cancel_work_sync(&ub->stop_work);
1475         cancel_work_sync(&ub->quiesce_work);
1476         cdev_device_del(&ub->cdev, &ub->cdev_dev);
1477         put_device(&ub->cdev_dev);
1478 }
1479
1480 static struct ublk_device *ublk_get_device_from_id(int idx)
1481 {
1482         struct ublk_device *ub = NULL;
1483
1484         if (idx < 0)
1485                 return NULL;
1486
1487         spin_lock(&ublk_idr_lock);
1488         ub = idr_find(&ublk_index_idr, idx);
1489         if (ub)
1490                 ub = ublk_get_device(ub);
1491         spin_unlock(&ublk_idr_lock);
1492
1493         return ub;
1494 }
1495
1496 static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
1497 {
1498         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1499         int ublksrv_pid = (int)header->data[0];
1500         struct ublk_device *ub;
1501         struct gendisk *disk;
1502         int ret = -EINVAL;
1503
1504         if (ublksrv_pid <= 0)
1505                 return -EINVAL;
1506
1507         ub = ublk_get_device_from_id(header->dev_id);
1508         if (!ub)
1509                 return -EINVAL;
1510
1511         wait_for_completion_interruptible(&ub->completion);
1512
1513         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
1514
1515         mutex_lock(&ub->mutex);
1516         if (ub->dev_info.state == UBLK_S_DEV_LIVE ||
1517             test_bit(UB_STATE_USED, &ub->state)) {
1518                 ret = -EEXIST;
1519                 goto out_unlock;
1520         }
1521
1522         disk = blk_mq_alloc_disk(&ub->tag_set, ub);
1523         if (IS_ERR(disk)) {
1524                 ret = PTR_ERR(disk);
1525                 goto out_unlock;
1526         }
1527         sprintf(disk->disk_name, "ublkb%d", ub->ub_number);
1528         disk->fops = &ub_fops;
1529         disk->private_data = ub;
1530
1531         ub->dev_info.ublksrv_pid = ublksrv_pid;
1532         ub->ub_disk = disk;
1533
1534         ret = ublk_apply_params(ub);
1535         if (ret)
1536                 goto out_put_disk;
1537
1538         get_device(&ub->cdev_dev);
1539         ret = add_disk(disk);
1540         if (ret) {
1541                 /*
1542                  * Has to drop the reference since ->free_disk won't be
1543                  * called in case of add_disk failure.
1544                  */
1545                 ublk_put_device(ub);
1546                 goto out_put_disk;
1547         }
1548         set_bit(UB_STATE_USED, &ub->state);
1549         ub->dev_info.state = UBLK_S_DEV_LIVE;
1550 out_put_disk:
1551         if (ret)
1552                 put_disk(disk);
1553 out_unlock:
1554         mutex_unlock(&ub->mutex);
1555         ublk_put_device(ub);
1556         return ret;
1557 }
1558
1559 static int ublk_ctrl_get_queue_affinity(struct io_uring_cmd *cmd)
1560 {
1561         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1562         void __user *argp = (void __user *)(unsigned long)header->addr;
1563         struct ublk_device *ub;
1564         cpumask_var_t cpumask;
1565         unsigned long queue;
1566         unsigned int retlen;
1567         unsigned int i;
1568         int ret = -EINVAL;
1569
1570         if (header->len * BITS_PER_BYTE < nr_cpu_ids)
1571                 return -EINVAL;
1572         if (header->len & (sizeof(unsigned long)-1))
1573                 return -EINVAL;
1574         if (!header->addr)
1575                 return -EINVAL;
1576
1577         ub = ublk_get_device_from_id(header->dev_id);
1578         if (!ub)
1579                 return -EINVAL;
1580
1581         queue = header->data[0];
1582         if (queue >= ub->dev_info.nr_hw_queues)
1583                 goto out_put_device;
1584
1585         ret = -ENOMEM;
1586         if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
1587                 goto out_put_device;
1588
1589         for_each_possible_cpu(i) {
1590                 if (ub->tag_set.map[HCTX_TYPE_DEFAULT].mq_map[i] == queue)
1591                         cpumask_set_cpu(i, cpumask);
1592         }
1593
1594         ret = -EFAULT;
1595         retlen = min_t(unsigned short, header->len, cpumask_size());
1596         if (copy_to_user(argp, cpumask, retlen))
1597                 goto out_free_cpumask;
1598         if (retlen != header->len &&
1599             clear_user(argp + retlen, header->len - retlen))
1600                 goto out_free_cpumask;
1601
1602         ret = 0;
1603 out_free_cpumask:
1604         free_cpumask_var(cpumask);
1605 out_put_device:
1606         ublk_put_device(ub);
1607         return ret;
1608 }
1609
1610 static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info)
1611 {
1612         pr_devel("%s: dev id %d flags %llx\n", __func__,
1613                         info->dev_id, info->flags);
1614         pr_devel("\t nr_hw_queues %d queue_depth %d\n",
1615                         info->nr_hw_queues, info->queue_depth);
1616 }
1617
1618 static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
1619 {
1620         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1621         void __user *argp = (void __user *)(unsigned long)header->addr;
1622         struct ublksrv_ctrl_dev_info info;
1623         struct ublk_device *ub;
1624         int ret = -EINVAL;
1625
1626         if (header->len < sizeof(info) || !header->addr)
1627                 return -EINVAL;
1628         if (header->queue_id != (u16)-1) {
1629                 pr_warn("%s: queue_id is wrong %x\n",
1630                         __func__, header->queue_id);
1631                 return -EINVAL;
1632         }
1633         if (copy_from_user(&info, argp, sizeof(info)))
1634                 return -EFAULT;
1635         ublk_dump_dev_info(&info);
1636         if (header->dev_id != info.dev_id) {
1637                 pr_warn("%s: dev id not match %u %u\n",
1638                         __func__, header->dev_id, info.dev_id);
1639                 return -EINVAL;
1640         }
1641
1642         ret = mutex_lock_killable(&ublk_ctl_mutex);
1643         if (ret)
1644                 return ret;
1645
1646         ret = -ENOMEM;
1647         ub = kzalloc(sizeof(*ub), GFP_KERNEL);
1648         if (!ub)
1649                 goto out_unlock;
1650         mutex_init(&ub->mutex);
1651         spin_lock_init(&ub->mm_lock);
1652         INIT_WORK(&ub->quiesce_work, ublk_quiesce_work_fn);
1653         INIT_WORK(&ub->stop_work, ublk_stop_work_fn);
1654         INIT_DELAYED_WORK(&ub->monitor_work, ublk_daemon_monitor_work);
1655
1656         ret = ublk_alloc_dev_number(ub, header->dev_id);
1657         if (ret < 0)
1658                 goto out_free_ub;
1659
1660         memcpy(&ub->dev_info, &info, sizeof(info));
1661
1662         /* update device id */
1663         ub->dev_info.dev_id = ub->ub_number;
1664
1665         /*
1666          * 64bit flags will be copied back to userspace as feature
1667          * negotiation result, so have to clear flags which driver
1668          * doesn't support yet, then userspace can get correct flags
1669          * (features) to handle.
1670          */
1671         ub->dev_info.flags &= UBLK_F_ALL;
1672
1673         if (!IS_BUILTIN(CONFIG_BLK_DEV_UBLK))
1674                 ub->dev_info.flags |= UBLK_F_URING_CMD_COMP_IN_TASK;
1675
1676         /* We are not ready to support zero copy */
1677         ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
1678
1679         ub->dev_info.nr_hw_queues = min_t(unsigned int,
1680                         ub->dev_info.nr_hw_queues, nr_cpu_ids);
1681         ublk_align_max_io_size(ub);
1682
1683         ret = ublk_init_queues(ub);
1684         if (ret)
1685                 goto out_free_dev_number;
1686
1687         ret = ublk_add_tag_set(ub);
1688         if (ret)
1689                 goto out_deinit_queues;
1690
1691         ret = -EFAULT;
1692         if (copy_to_user(argp, &ub->dev_info, sizeof(info)))
1693                 goto out_free_tag_set;
1694
1695         /*
1696          * Add the char dev so that ublksrv daemon can be setup.
1697          * ublk_add_chdev() will cleanup everything if it fails.
1698          */
1699         ret = ublk_add_chdev(ub);
1700         goto out_unlock;
1701
1702 out_free_tag_set:
1703         blk_mq_free_tag_set(&ub->tag_set);
1704 out_deinit_queues:
1705         ublk_deinit_queues(ub);
1706 out_free_dev_number:
1707         ublk_free_dev_number(ub);
1708 out_free_ub:
1709         mutex_destroy(&ub->mutex);
1710         kfree(ub);
1711 out_unlock:
1712         mutex_unlock(&ublk_ctl_mutex);
1713         return ret;
1714 }
1715
1716 static inline bool ublk_idr_freed(int id)
1717 {
1718         void *ptr;
1719
1720         spin_lock(&ublk_idr_lock);
1721         ptr = idr_find(&ublk_index_idr, id);
1722         spin_unlock(&ublk_idr_lock);
1723
1724         return ptr == NULL;
1725 }
1726
1727 static int ublk_ctrl_del_dev(int idx)
1728 {
1729         struct ublk_device *ub;
1730         int ret;
1731
1732         ret = mutex_lock_killable(&ublk_ctl_mutex);
1733         if (ret)
1734                 return ret;
1735
1736         ub = ublk_get_device_from_id(idx);
1737         if (ub) {
1738                 ublk_remove(ub);
1739                 ublk_put_device(ub);
1740                 ret = 0;
1741         } else {
1742                 ret = -ENODEV;
1743         }
1744
1745         /*
1746          * Wait until the idr is removed, then it can be reused after
1747          * DEL_DEV command is returned.
1748          */
1749         if (!ret)
1750                 wait_event(ublk_idr_wq, ublk_idr_freed(idx));
1751         mutex_unlock(&ublk_ctl_mutex);
1752
1753         return ret;
1754 }
1755
1756 static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd)
1757 {
1758         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1759
1760         pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n",
1761                         __func__, cmd->cmd_op, header->dev_id, header->queue_id,
1762                         header->data[0], header->addr, header->len);
1763 }
1764
1765 static int ublk_ctrl_stop_dev(struct io_uring_cmd *cmd)
1766 {
1767         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1768         struct ublk_device *ub;
1769
1770         ub = ublk_get_device_from_id(header->dev_id);
1771         if (!ub)
1772                 return -EINVAL;
1773
1774         ublk_stop_dev(ub);
1775         cancel_work_sync(&ub->stop_work);
1776         cancel_work_sync(&ub->quiesce_work);
1777
1778         ublk_put_device(ub);
1779         return 0;
1780 }
1781
1782 static int ublk_ctrl_get_dev_info(struct io_uring_cmd *cmd)
1783 {
1784         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1785         void __user *argp = (void __user *)(unsigned long)header->addr;
1786         struct ublk_device *ub;
1787         int ret = 0;
1788
1789         if (header->len < sizeof(struct ublksrv_ctrl_dev_info) || !header->addr)
1790                 return -EINVAL;
1791
1792         ub = ublk_get_device_from_id(header->dev_id);
1793         if (!ub)
1794                 return -EINVAL;
1795
1796         if (copy_to_user(argp, &ub->dev_info, sizeof(ub->dev_info)))
1797                 ret = -EFAULT;
1798         ublk_put_device(ub);
1799
1800         return ret;
1801 }
1802
1803 static int ublk_ctrl_get_params(struct io_uring_cmd *cmd)
1804 {
1805         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1806         void __user *argp = (void __user *)(unsigned long)header->addr;
1807         struct ublk_params_header ph;
1808         struct ublk_device *ub;
1809         int ret;
1810
1811         if (header->len <= sizeof(ph) || !header->addr)
1812                 return -EINVAL;
1813
1814         if (copy_from_user(&ph, argp, sizeof(ph)))
1815                 return -EFAULT;
1816
1817         if (ph.len > header->len || !ph.len)
1818                 return -EINVAL;
1819
1820         if (ph.len > sizeof(struct ublk_params))
1821                 ph.len = sizeof(struct ublk_params);
1822
1823         ub = ublk_get_device_from_id(header->dev_id);
1824         if (!ub)
1825                 return -EINVAL;
1826
1827         mutex_lock(&ub->mutex);
1828         if (copy_to_user(argp, &ub->params, ph.len))
1829                 ret = -EFAULT;
1830         else
1831                 ret = 0;
1832         mutex_unlock(&ub->mutex);
1833
1834         ublk_put_device(ub);
1835         return ret;
1836 }
1837
1838 static int ublk_ctrl_set_params(struct io_uring_cmd *cmd)
1839 {
1840         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1841         void __user *argp = (void __user *)(unsigned long)header->addr;
1842         struct ublk_params_header ph;
1843         struct ublk_device *ub;
1844         int ret = -EFAULT;
1845
1846         if (header->len <= sizeof(ph) || !header->addr)
1847                 return -EINVAL;
1848
1849         if (copy_from_user(&ph, argp, sizeof(ph)))
1850                 return -EFAULT;
1851
1852         if (ph.len > header->len || !ph.len || !ph.types)
1853                 return -EINVAL;
1854
1855         if (ph.len > sizeof(struct ublk_params))
1856                 ph.len = sizeof(struct ublk_params);
1857
1858         ub = ublk_get_device_from_id(header->dev_id);
1859         if (!ub)
1860                 return -EINVAL;
1861
1862         /* parameters can only be changed when device isn't live */
1863         mutex_lock(&ub->mutex);
1864         if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
1865                 ret = -EACCES;
1866         } else if (copy_from_user(&ub->params, argp, ph.len)) {
1867                 ret = -EFAULT;
1868         } else {
1869                 /* clear all we don't support yet */
1870                 ub->params.types &= UBLK_PARAM_TYPE_ALL;
1871                 ret = ublk_validate_params(ub);
1872         }
1873         mutex_unlock(&ub->mutex);
1874         ublk_put_device(ub);
1875
1876         return ret;
1877 }
1878
1879 static void ublk_queue_reinit(struct ublk_device *ub, struct ublk_queue *ubq)
1880 {
1881         int i;
1882
1883         WARN_ON_ONCE(!(ubq->ubq_daemon && ubq_daemon_is_dying(ubq)));
1884         /* All old ioucmds have to be completed */
1885         WARN_ON_ONCE(ubq->nr_io_ready);
1886         /* old daemon is PF_EXITING, put it now */
1887         put_task_struct(ubq->ubq_daemon);
1888         /* We have to reset it to NULL, otherwise ub won't accept new FETCH_REQ */
1889         ubq->ubq_daemon = NULL;
1890
1891         for (i = 0; i < ubq->q_depth; i++) {
1892                 struct ublk_io *io = &ubq->ios[i];
1893
1894                 /* forget everything now and be ready for new FETCH_REQ */
1895                 io->flags = 0;
1896                 io->cmd = NULL;
1897                 io->addr = 0;
1898         }
1899 }
1900
1901 static int ublk_ctrl_start_recovery(struct io_uring_cmd *cmd)
1902 {
1903         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1904         struct ublk_device *ub;
1905         int ret = -EINVAL;
1906         int i;
1907
1908         ub = ublk_get_device_from_id(header->dev_id);
1909         if (!ub)
1910                 return ret;
1911
1912         mutex_lock(&ub->mutex);
1913         if (!ublk_can_use_recovery(ub))
1914                 goto out_unlock;
1915         /*
1916          * START_RECOVERY is only allowd after:
1917          *
1918          * (1) UB_STATE_OPEN is not set, which means the dying process is exited
1919          *     and related io_uring ctx is freed so file struct of /dev/ublkcX is
1920          *     released.
1921          *
1922          * (2) UBLK_S_DEV_QUIESCED is set, which means the quiesce_work:
1923          *     (a)has quiesced request queue
1924          *     (b)has requeued every inflight rqs whose io_flags is ACTIVE
1925          *     (c)has requeued/aborted every inflight rqs whose io_flags is NOT ACTIVE
1926          *     (d)has completed/camceled all ioucmds owned by ther dying process
1927          */
1928         if (test_bit(UB_STATE_OPEN, &ub->state) ||
1929                         ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
1930                 ret = -EBUSY;
1931                 goto out_unlock;
1932         }
1933         pr_devel("%s: start recovery for dev id %d.\n", __func__, header->dev_id);
1934         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
1935                 ublk_queue_reinit(ub, ublk_get_queue(ub, i));
1936         /* set to NULL, otherwise new ubq_daemon cannot mmap the io_cmd_buf */
1937         ub->mm = NULL;
1938         ub->nr_queues_ready = 0;
1939         init_completion(&ub->completion);
1940         ret = 0;
1941  out_unlock:
1942         mutex_unlock(&ub->mutex);
1943         ublk_put_device(ub);
1944         return ret;
1945 }
1946
1947 static int ublk_ctrl_end_recovery(struct io_uring_cmd *cmd)
1948 {
1949         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1950         int ublksrv_pid = (int)header->data[0];
1951         struct ublk_device *ub;
1952         int ret = -EINVAL;
1953
1954         ub = ublk_get_device_from_id(header->dev_id);
1955         if (!ub)
1956                 return ret;
1957
1958         pr_devel("%s: Waiting for new ubq_daemons(nr: %d) are ready, dev id %d...\n",
1959                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
1960         /* wait until new ubq_daemon sending all FETCH_REQ */
1961         wait_for_completion_interruptible(&ub->completion);
1962         pr_devel("%s: All new ubq_daemons(nr: %d) are ready, dev id %d\n",
1963                         __func__, ub->dev_info.nr_hw_queues, header->dev_id);
1964
1965         mutex_lock(&ub->mutex);
1966         if (!ublk_can_use_recovery(ub))
1967                 goto out_unlock;
1968
1969         if (ub->dev_info.state != UBLK_S_DEV_QUIESCED) {
1970                 ret = -EBUSY;
1971                 goto out_unlock;
1972         }
1973         ub->dev_info.ublksrv_pid = ublksrv_pid;
1974         pr_devel("%s: new ublksrv_pid %d, dev id %d\n",
1975                         __func__, ublksrv_pid, header->dev_id);
1976         blk_mq_unquiesce_queue(ub->ub_disk->queue);
1977         pr_devel("%s: queue unquiesced, dev id %d.\n",
1978                         __func__, header->dev_id);
1979         blk_mq_kick_requeue_list(ub->ub_disk->queue);
1980         ub->dev_info.state = UBLK_S_DEV_LIVE;
1981         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
1982         ret = 0;
1983  out_unlock:
1984         mutex_unlock(&ub->mutex);
1985         ublk_put_device(ub);
1986         return ret;
1987 }
1988
1989 static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
1990                 unsigned int issue_flags)
1991 {
1992         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1993         int ret = -EINVAL;
1994
1995         if (issue_flags & IO_URING_F_NONBLOCK)
1996                 return -EAGAIN;
1997
1998         ublk_ctrl_cmd_dump(cmd);
1999
2000         if (!(issue_flags & IO_URING_F_SQE128))
2001                 goto out;
2002
2003         ret = -EPERM;
2004         if (!capable(CAP_SYS_ADMIN))
2005                 goto out;
2006
2007         ret = -ENODEV;
2008         switch (cmd->cmd_op) {
2009         case UBLK_CMD_START_DEV:
2010                 ret = ublk_ctrl_start_dev(cmd);
2011                 break;
2012         case UBLK_CMD_STOP_DEV:
2013                 ret = ublk_ctrl_stop_dev(cmd);
2014                 break;
2015         case UBLK_CMD_GET_DEV_INFO:
2016                 ret = ublk_ctrl_get_dev_info(cmd);
2017                 break;
2018         case UBLK_CMD_ADD_DEV:
2019                 ret = ublk_ctrl_add_dev(cmd);
2020                 break;
2021         case UBLK_CMD_DEL_DEV:
2022                 ret = ublk_ctrl_del_dev(header->dev_id);
2023                 break;
2024         case UBLK_CMD_GET_QUEUE_AFFINITY:
2025                 ret = ublk_ctrl_get_queue_affinity(cmd);
2026                 break;
2027         case UBLK_CMD_GET_PARAMS:
2028                 ret = ublk_ctrl_get_params(cmd);
2029                 break;
2030         case UBLK_CMD_SET_PARAMS:
2031                 ret = ublk_ctrl_set_params(cmd);
2032                 break;
2033         case UBLK_CMD_START_USER_RECOVERY:
2034                 ret = ublk_ctrl_start_recovery(cmd);
2035                 break;
2036         case UBLK_CMD_END_USER_RECOVERY:
2037                 ret = ublk_ctrl_end_recovery(cmd);
2038                 break;
2039         default:
2040                 break;
2041         }
2042  out:
2043         io_uring_cmd_done(cmd, ret, 0);
2044         pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n",
2045                         __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id);
2046         return -EIOCBQUEUED;
2047 }
2048
2049 static const struct file_operations ublk_ctl_fops = {
2050         .open           = nonseekable_open,
2051         .uring_cmd      = ublk_ctrl_uring_cmd,
2052         .owner          = THIS_MODULE,
2053         .llseek         = noop_llseek,
2054 };
2055
2056 static struct miscdevice ublk_misc = {
2057         .minor          = MISC_DYNAMIC_MINOR,
2058         .name           = "ublk-control",
2059         .fops           = &ublk_ctl_fops,
2060 };
2061
2062 static int __init ublk_init(void)
2063 {
2064         int ret;
2065
2066         init_waitqueue_head(&ublk_idr_wq);
2067
2068         ret = misc_register(&ublk_misc);
2069         if (ret)
2070                 return ret;
2071
2072         ret = alloc_chrdev_region(&ublk_chr_devt, 0, UBLK_MINORS, "ublk-char");
2073         if (ret)
2074                 goto unregister_mis;
2075
2076         ublk_chr_class = class_create(THIS_MODULE, "ublk-char");
2077         if (IS_ERR(ublk_chr_class)) {
2078                 ret = PTR_ERR(ublk_chr_class);
2079                 goto free_chrdev_region;
2080         }
2081         return 0;
2082
2083 free_chrdev_region:
2084         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2085 unregister_mis:
2086         misc_deregister(&ublk_misc);
2087         return ret;
2088 }
2089
2090 static void __exit ublk_exit(void)
2091 {
2092         struct ublk_device *ub;
2093         int id;
2094
2095         idr_for_each_entry(&ublk_index_idr, ub, id)
2096                 ublk_remove(ub);
2097
2098         class_destroy(ublk_chr_class);
2099         misc_deregister(&ublk_misc);
2100
2101         idr_destroy(&ublk_index_idr);
2102         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
2103 }
2104
2105 module_init(ublk_init);
2106 module_exit(ublk_exit);
2107
2108 MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>");
2109 MODULE_LICENSE("GPL");