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 struct ublk_rq_data {
  50         struct callback_head work;
  51 };
  52
  53 struct ublk_uring_cmd_pdu {
  54         struct request *req;
  55 };
  56
  57 /*
  58  * io command is active: sqe cmd is received, and its cqe isn't done
  59  *
  60  * If the flag is set, the io command is owned by ublk driver, and waited
  61  * for incoming blk-mq request from the ublk block device.
  62  *
  63  * If the flag is cleared, the io command will be completed, and owned by
  64  * ublk server.
  65  */
  66 #define UBLK_IO_FLAG_ACTIVE     0x01
  67
  68 /*
  69  * IO command is completed via cqe, and it is being handled by ublksrv, and
  70  * not committed yet
  71  *
  72  * Basically exclusively with UBLK_IO_FLAG_ACTIVE, so can be served for
  73  * cross verification
  74  */
  75 #define UBLK_IO_FLAG_OWNED_BY_SRV 0x02
  76
  77 /*
  78  * IO command is aborted, so this flag is set in case of
  79  * !UBLK_IO_FLAG_ACTIVE.
  80  *
  81  * After this flag is observed, any pending or new incoming request
  82  * associated with this io command will be failed immediately
  83  */
  84 #define UBLK_IO_FLAG_ABORTED 0x04
  85
  86 struct ublk_io {
  87         /* userspace buffer address from io cmd */
  88         __u64   addr;
  89         unsigned int flags;
  90         int res;
  91
  92         struct io_uring_cmd *cmd;
  93 };
  94
  95 struct ublk_queue {
  96         int q_id;
  97         int q_depth;
  98
  99         unsigned long flags;
 100         struct task_struct      *ubq_daemon;
 101         char *io_cmd_buf;
 102
 103         unsigned long io_addr;  /* mapped vm address */
 104         unsigned int max_io_sz;
 105         bool abort_work_pending;
 106         unsigned short nr_io_ready;     /* how many ios setup */
 107         struct ublk_device *dev;
 108         struct ublk_io ios[0];
 109 };
 110
 111 #define UBLK_DAEMON_MONITOR_PERIOD      (5 * HZ)
 112
 113 struct ublk_device {
 114         struct gendisk          *ub_disk;
 115         struct request_queue    *ub_queue;
 116
 117         char    *__queues;
 118
 119         unsigned short  queue_size;
 120         unsigned short  bs_shift;
 121         struct ublksrv_ctrl_dev_info    dev_info;
 122
 123         struct blk_mq_tag_set   tag_set;
 124
 125         struct cdev             cdev;
 126         struct device           cdev_dev;
 127
 128         atomic_t                ch_open_cnt;
 129         int                     ub_number;
 130
 131         struct mutex            mutex;
 132
 133         struct mm_struct        *mm;
 134
 135         struct completion       completion;
 136         unsigned int            nr_queues_ready;
 137         atomic_t                nr_aborted_queues;
 138
 139         /*
 140          * Our ubq->daemon may be killed without any notification, so
 141          * monitor each queue's daemon periodically
 142          */
 143         struct delayed_work     monitor_work;
 144         struct work_struct      stop_work;
 145 };
 146
 147 static dev_t ublk_chr_devt;
 148 static struct class *ublk_chr_class;
 149
 150 static DEFINE_IDR(ublk_index_idr);
 151 static DEFINE_SPINLOCK(ublk_idr_lock);
 152 static wait_queue_head_t ublk_idr_wq;   /* wait until one idr is freed */
 153
 154 static DEFINE_MUTEX(ublk_ctl_mutex);
 155
 156 static struct miscdevice ublk_misc;
 157
 158 static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq)
 159 {
 160         if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) &&
 161                         !(ubq->flags & UBLK_F_URING_CMD_COMP_IN_TASK))
 162                 return true;
 163         return false;
 164 }
 165
 166 static struct ublk_device *ublk_get_device(struct ublk_device *ub)
 167 {
 168         if (kobject_get_unless_zero(&ub->cdev_dev.kobj))
 169                 return ub;
 170         return NULL;
 171 }
 172
 173 static void ublk_put_device(struct ublk_device *ub)
 174 {
 175         put_device(&ub->cdev_dev);
 176 }
 177
 178 static inline struct ublk_queue *ublk_get_queue(struct ublk_device *dev,
 179                 int qid)
 180 {
 181        return (struct ublk_queue *)&(dev->__queues[qid * dev->queue_size]);
 182 }
 183
 184 static inline bool ublk_rq_has_data(const struct request *rq)
 185 {
 186         return rq->bio && bio_has_data(rq->bio);
 187 }
 188
 189 static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq,
 190                 int tag)
 191 {
 192         return (struct ublksrv_io_desc *)
 193                 &(ubq->io_cmd_buf[tag * sizeof(struct ublksrv_io_desc)]);
 194 }
 195
 196 static inline char *ublk_queue_cmd_buf(struct ublk_device *ub, int q_id)
 197 {
 198         return ublk_get_queue(ub, q_id)->io_cmd_buf;
 199 }
 200
 201 static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
 202 {
 203         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 204
 205         return round_up(ubq->q_depth * sizeof(struct ublksrv_io_desc),
 206                         PAGE_SIZE);
 207 }
 208
 209 static int ublk_open(struct block_device *bdev, fmode_t mode)
 210 {
 211         return 0;
 212 }
 213
 214 static void ublk_release(struct gendisk *disk, fmode_t mode)
 215 {
 216 }
 217
 218 static const struct block_device_operations ub_fops = {
 219         .owner =        THIS_MODULE,
 220         .open =         ublk_open,
 221         .release =      ublk_release,
 222 };
 223
 224 #define UBLK_MAX_PIN_PAGES      32
 225
 226 struct ublk_map_data {
 227         const struct ublk_queue *ubq;
 228         const struct request *rq;
 229         const struct ublk_io *io;
 230         unsigned max_bytes;
 231 };
 232
 233 struct ublk_io_iter {
 234         struct page *pages[UBLK_MAX_PIN_PAGES];
 235         unsigned pg_off;        /* offset in the 1st page in pages */
 236         int nr_pages;           /* how many page pointers in pages */
 237         struct bio *bio;
 238         struct bvec_iter iter;
 239 };
 240
 241 static inline unsigned ublk_copy_io_pages(struct ublk_io_iter *data,
 242                 unsigned max_bytes, bool to_vm)
 243 {
 244         const unsigned total = min_t(unsigned, max_bytes,
 245                         PAGE_SIZE - data->pg_off +
 246                         ((data->nr_pages - 1) << PAGE_SHIFT));
 247         unsigned done = 0;
 248         unsigned pg_idx = 0;
 249
 250         while (done < total) {
 251                 struct bio_vec bv = bio_iter_iovec(data->bio, data->iter);
 252                 const unsigned int bytes = min3(bv.bv_len, total - done,
 253                                 (unsigned)(PAGE_SIZE - data->pg_off));
 254                 void *bv_buf = bvec_kmap_local(&bv);
 255                 void *pg_buf = kmap_local_page(data->pages[pg_idx]);
 256
 257                 if (to_vm)
 258                         memcpy(pg_buf + data->pg_off, bv_buf, bytes);
 259                 else
 260                         memcpy(bv_buf, pg_buf + data->pg_off, bytes);
 261
 262                 kunmap_local(pg_buf);
 263                 kunmap_local(bv_buf);
 264
 265                 /* advance page array */
 266                 data->pg_off += bytes;
 267                 if (data->pg_off == PAGE_SIZE) {
 268                         pg_idx += 1;
 269                         data->pg_off = 0;
 270                 }
 271
 272                 done += bytes;
 273
 274                 /* advance bio */
 275                 bio_advance_iter_single(data->bio, &data->iter, bytes);
 276                 if (!data->iter.bi_size) {
 277                         data->bio = data->bio->bi_next;
 278                         if (data->bio == NULL)
 279                                 break;
 280                         data->iter = data->bio->bi_iter;
 281                 }
 282         }
 283
 284         return done;
 285 }
 286
 287 static inline int ublk_copy_user_pages(struct ublk_map_data *data,
 288                 bool to_vm)
 289 {
 290         const unsigned int gup_flags = to_vm ? FOLL_WRITE : 0;
 291         const unsigned long start_vm = data->io->addr;
 292         unsigned int done = 0;
 293         struct ublk_io_iter iter = {
 294                 .pg_off = start_vm & (PAGE_SIZE - 1),
 295                 .bio    = data->rq->bio,
 296                 .iter   = data->rq->bio->bi_iter,
 297         };
 298         const unsigned int nr_pages = round_up(data->max_bytes +
 299                         (start_vm & (PAGE_SIZE - 1)), PAGE_SIZE) >> PAGE_SHIFT;
 300
 301         while (done < nr_pages) {
 302                 const unsigned to_pin = min_t(unsigned, UBLK_MAX_PIN_PAGES,
 303                                 nr_pages - done);
 304                 unsigned i, len;
 305
 306                 iter.nr_pages = get_user_pages_fast(start_vm +
 307                                 (done << PAGE_SHIFT), to_pin, gup_flags,
 308                                 iter.pages);
 309                 if (iter.nr_pages <= 0)
 310                         return done == 0 ? iter.nr_pages : done;
 311                 len = ublk_copy_io_pages(&iter, data->max_bytes, to_vm);
 312                 for (i = 0; i < iter.nr_pages; i++) {
 313                         if (to_vm)
 314                                 set_page_dirty(iter.pages[i]);
 315                         put_page(iter.pages[i]);
 316                 }
 317                 data->max_bytes -= len;
 318                 done += iter.nr_pages;
 319         }
 320
 321         return done;
 322 }
 323
 324 static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
 325                 struct ublk_io *io)
 326 {
 327         const unsigned int rq_bytes = blk_rq_bytes(req);
 328         /*
 329          * no zero copy, we delay copy WRITE request data into ublksrv
 330          * context and the big benefit is that pinning pages in current
 331          * context is pretty fast, see ublk_pin_user_pages
 332          */
 333         if (req_op(req) != REQ_OP_WRITE && req_op(req) != REQ_OP_FLUSH)
 334                 return rq_bytes;
 335
 336         if (ublk_rq_has_data(req)) {
 337                 struct ublk_map_data data = {
 338                         .ubq    =       ubq,
 339                         .rq     =       req,
 340                         .io     =       io,
 341                         .max_bytes =    rq_bytes,
 342                 };
 343
 344                 ublk_copy_user_pages(&data, true);
 345
 346                 return rq_bytes - data.max_bytes;
 347         }
 348         return rq_bytes;
 349 }
 350
 351 static int ublk_unmap_io(const struct ublk_queue *ubq,
 352                 const struct request *req,
 353                 struct ublk_io *io)
 354 {
 355         const unsigned int rq_bytes = blk_rq_bytes(req);
 356
 357         if (req_op(req) == REQ_OP_READ && ublk_rq_has_data(req)) {
 358                 struct ublk_map_data data = {
 359                         .ubq    =       ubq,
 360                         .rq     =       req,
 361                         .io     =       io,
 362                         .max_bytes =    io->res,
 363                 };
 364
 365                 WARN_ON_ONCE(io->res > rq_bytes);
 366
 367                 ublk_copy_user_pages(&data, false);
 368
 369                 return io->res - data.max_bytes;
 370         }
 371         return rq_bytes;
 372 }
 373
 374 static inline unsigned int ublk_req_build_flags(struct request *req)
 375 {
 376         unsigned flags = 0;
 377
 378         if (req->cmd_flags & REQ_FAILFAST_DEV)
 379                 flags |= UBLK_IO_F_FAILFAST_DEV;
 380
 381         if (req->cmd_flags & REQ_FAILFAST_TRANSPORT)
 382                 flags |= UBLK_IO_F_FAILFAST_TRANSPORT;
 383
 384         if (req->cmd_flags & REQ_FAILFAST_DRIVER)
 385                 flags |= UBLK_IO_F_FAILFAST_DRIVER;
 386
 387         if (req->cmd_flags & REQ_META)
 388                 flags |= UBLK_IO_F_META;
 389
 390         if (req->cmd_flags & REQ_INTEGRITY)
 391                 flags |= UBLK_IO_F_INTEGRITY;
 392
 393         if (req->cmd_flags & REQ_FUA)
 394                 flags |= UBLK_IO_F_FUA;
 395
 396         if (req->cmd_flags & REQ_PREFLUSH)
 397                 flags |= UBLK_IO_F_PREFLUSH;
 398
 399         if (req->cmd_flags & REQ_NOUNMAP)
 400                 flags |= UBLK_IO_F_NOUNMAP;
 401
 402         if (req->cmd_flags & REQ_SWAP)
 403                 flags |= UBLK_IO_F_SWAP;
 404
 405         return flags;
 406 }
 407
 408 static int ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 409 {
 410         struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
 411         struct ublk_io *io = &ubq->ios[req->tag];
 412         u32 ublk_op;
 413
 414         switch (req_op(req)) {
 415         case REQ_OP_READ:
 416                 ublk_op = UBLK_IO_OP_READ;
 417                 break;
 418         case REQ_OP_WRITE:
 419                 ublk_op = UBLK_IO_OP_WRITE;
 420                 break;
 421         case REQ_OP_FLUSH:
 422                 ublk_op = UBLK_IO_OP_FLUSH;
 423                 break;
 424         case REQ_OP_DISCARD:
 425                 ublk_op = UBLK_IO_OP_DISCARD;
 426                 break;
 427         case REQ_OP_WRITE_ZEROES:
 428                 ublk_op = UBLK_IO_OP_WRITE_ZEROES;
 429                 break;
 430         default:
 431                 return BLK_STS_IOERR;
 432         }
 433
 434         /* need to translate since kernel may change */
 435         iod->op_flags = ublk_op | ublk_req_build_flags(req);
 436         iod->nr_sectors = blk_rq_sectors(req);
 437         iod->start_sector = blk_rq_pos(req);
 438         iod->addr = io->addr;
 439
 440         return BLK_STS_OK;
 441 }
 442
 443 static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu(
 444                 struct io_uring_cmd *ioucmd)
 445 {
 446         return (struct ublk_uring_cmd_pdu *)&ioucmd->pdu;
 447 }
 448
 449 static bool ubq_daemon_is_dying(struct ublk_queue *ubq)
 450 {
 451         return ubq->ubq_daemon->flags & PF_EXITING;
 452 }
 453
 454 /* todo: handle partial completion */
 455 static void ublk_complete_rq(struct request *req)
 456 {
 457         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 458         struct ublk_io *io = &ubq->ios[req->tag];
 459         unsigned int unmapped_bytes;
 460
 461         /* failed read IO if nothing is read */
 462         if (!io->res && req_op(req) == REQ_OP_READ)
 463                 io->res = -EIO;
 464
 465         if (io->res < 0) {
 466                 blk_mq_end_request(req, errno_to_blk_status(io->res));
 467                 return;
 468         }
 469
 470         /*
 471          * FLUSH or DISCARD usually won't return bytes returned, so end them
 472          * directly.
 473          *
 474          * Both the two needn't unmap.
 475          */
 476         if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE) {
 477                 blk_mq_end_request(req, BLK_STS_OK);
 478                 return;
 479         }
 480
 481         /* for READ request, writing data in iod->addr to rq buffers */
 482         unmapped_bytes = ublk_unmap_io(ubq, req, io);
 483
 484         /*
 485          * Extremely impossible since we got data filled in just before
 486          *
 487          * Re-read simply for this unlikely case.
 488          */
 489         if (unlikely(unmapped_bytes < io->res))
 490                 io->res = unmapped_bytes;
 491
 492         if (blk_update_request(req, BLK_STS_OK, io->res))
 493                 blk_mq_requeue_request(req, true);
 494         else
 495                 __blk_mq_end_request(req, BLK_STS_OK);
 496 }
 497
 498 /*
 499  * __ublk_fail_req() may be called from abort context or ->ubq_daemon
 500  * context during exiting, so lock is required.
 501  *
 502  * Also aborting may not be started yet, keep in mind that one failed
 503  * request may be issued by block layer again.
 504  */
 505 static void __ublk_fail_req(struct ublk_io *io, struct request *req)
 506 {
 507         WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
 508
 509         if (!(io->flags & UBLK_IO_FLAG_ABORTED)) {
 510                 io->flags |= UBLK_IO_FLAG_ABORTED;
 511                 blk_mq_end_request(req, BLK_STS_IOERR);
 512         }
 513 }
 514
 515 #define UBLK_REQUEUE_DELAY_MS   3
 516
 517 static inline void __ublk_rq_task_work(struct request *req)
 518 {
 519         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 520         struct ublk_device *ub = ubq->dev;
 521         int tag = req->tag;
 522         struct ublk_io *io = &ubq->ios[tag];
 523         bool task_exiting = current != ubq->ubq_daemon ||
 524                 (current->flags & PF_EXITING);
 525         unsigned int mapped_bytes;
 526
 527         pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",
 528                         __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 529                         ublk_get_iod(ubq, req->tag)->addr);
 530
 531         if (unlikely(task_exiting)) {
 532                 blk_mq_end_request(req, BLK_STS_IOERR);
 533                 mod_delayed_work(system_wq, &ub->monitor_work, 0);
 534                 return;
 535         }
 536
 537         mapped_bytes = ublk_map_io(ubq, req, io);
 538
 539         /* partially mapped, update io descriptor */
 540         if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
 541                 /*
 542                  * Nothing mapped, retry until we succeed.
 543                  *
 544                  * We may never succeed in mapping any bytes here because
 545                  * of OOM. TODO: reserve one buffer with single page pinned
 546                  * for providing forward progress guarantee.
 547                  */
 548                 if (unlikely(!mapped_bytes)) {
 549                         blk_mq_requeue_request(req, false);
 550                         blk_mq_delay_kick_requeue_list(req->q,
 551                                         UBLK_REQUEUE_DELAY_MS);
 552                         return;
 553                 }
 554
 555                 ublk_get_iod(ubq, req->tag)->nr_sectors =
 556                         mapped_bytes >> 9;
 557         }
 558
 559         /* mark this cmd owned by ublksrv */
 560         io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV;
 561
 562         /*
 563          * clear ACTIVE since we are done with this sqe/cmd slot
 564          * We can only accept io cmd in case of being not active.
 565          */
 566         io->flags &= ~UBLK_IO_FLAG_ACTIVE;
 567
 568         /* tell ublksrv one io request is coming */
 569         io_uring_cmd_done(io->cmd, UBLK_IO_RES_OK, 0);
 570 }
 571
 572 static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd)
 573 {
 574         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 575
 576         __ublk_rq_task_work(pdu->req);
 577 }
 578
 579 static void ublk_rq_task_work_fn(struct callback_head *work)
 580 {
 581         struct ublk_rq_data *data = container_of(work,
 582                         struct ublk_rq_data, work);
 583         struct request *req = blk_mq_rq_from_pdu(data);
 584
 585         __ublk_rq_task_work(req);
 586 }
 587
 588 static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
 589                 const struct blk_mq_queue_data *bd)
 590 {
 591         struct ublk_queue *ubq = hctx->driver_data;
 592         struct request *rq = bd->rq;
 593         blk_status_t res;
 594
 595         /* fill iod to slot in io cmd buffer */
 596         res = ublk_setup_iod(ubq, rq);
 597         if (unlikely(res != BLK_STS_OK))
 598                 return BLK_STS_IOERR;
 599
 600         blk_mq_start_request(bd->rq);
 601
 602         if (unlikely(ubq_daemon_is_dying(ubq))) {
 603  fail:
 604                 mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0);
 605                 return BLK_STS_IOERR;
 606         }
 607
 608         if (ublk_can_use_task_work(ubq)) {
 609                 struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
 610                 enum task_work_notify_mode notify_mode = bd->last ?
 611                         TWA_SIGNAL_NO_IPI : TWA_NONE;
 612
 613                 if (task_work_add(ubq->ubq_daemon, &data->work, notify_mode))
 614                         goto fail;
 615         } else {
 616                 struct io_uring_cmd *cmd = ubq->ios[rq->tag].cmd;
 617                 struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 618
 619                 pdu->req = rq;
 620                 io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb);
 621         }
 622
 623         return BLK_STS_OK;
 624 }
 625
 626 static void ublk_commit_rqs(struct blk_mq_hw_ctx *hctx)
 627 {
 628         struct ublk_queue *ubq = hctx->driver_data;
 629
 630         if (ublk_can_use_task_work(ubq))
 631                 __set_notify_signal(ubq->ubq_daemon);
 632 }
 633
 634 static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
 635                 unsigned int hctx_idx)
 636 {
 637         struct ublk_device *ub = hctx->queue->queuedata;
 638         struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num);
 639
 640         hctx->driver_data = ubq;
 641         return 0;
 642 }
 643
 644 static int ublk_init_rq(struct blk_mq_tag_set *set, struct request *req,
 645                 unsigned int hctx_idx, unsigned int numa_node)
 646 {
 647         struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 648
 649         init_task_work(&data->work, ublk_rq_task_work_fn);
 650         return 0;
 651 }
 652
 653 static const struct blk_mq_ops ublk_mq_ops = {
 654         .queue_rq       = ublk_queue_rq,
 655         .commit_rqs     = ublk_commit_rqs,
 656         .init_hctx      = ublk_init_hctx,
 657         .init_request   = ublk_init_rq,
 658 };
 659
 660 static int ublk_ch_open(struct inode *inode, struct file *filp)
 661 {
 662         struct ublk_device *ub = container_of(inode->i_cdev,
 663                         struct ublk_device, cdev);
 664
 665         if (atomic_cmpxchg(&ub->ch_open_cnt, 0, 1) == 0) {
 666                 filp->private_data = ub;
 667                 return 0;
 668         }
 669         return -EBUSY;
 670 }
 671
 672 static int ublk_ch_release(struct inode *inode, struct file *filp)
 673 {
 674         struct ublk_device *ub = filp->private_data;
 675
 676         while (atomic_cmpxchg(&ub->ch_open_cnt, 1, 0) != 1)
 677                 cpu_relax();
 678
 679         filp->private_data = NULL;
 680         return 0;
 681 }
 682
 683 /* map pre-allocated per-queue cmd buffer to ublksrv daemon */
 684 static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
 685 {
 686         struct ublk_device *ub = filp->private_data;
 687         size_t sz = vma->vm_end - vma->vm_start;
 688         unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc);
 689         unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT;
 690         int q_id, ret = 0;
 691
 692         mutex_lock(&ub->mutex);
 693         if (!ub->mm)
 694                 ub->mm = current->mm;
 695         if (current->mm != ub->mm)
 696                 ret = -EINVAL;
 697         mutex_unlock(&ub->mutex);
 698
 699         if (ret)
 700                 return ret;
 701
 702         if (vma->vm_flags & VM_WRITE)
 703                 return -EPERM;
 704
 705         end = UBLKSRV_CMD_BUF_OFFSET + ub->dev_info.nr_hw_queues * max_sz;
 706         if (phys_off < UBLKSRV_CMD_BUF_OFFSET || phys_off >= end)
 707                 return -EINVAL;
 708
 709         q_id = (phys_off - UBLKSRV_CMD_BUF_OFFSET) / max_sz;
 710         pr_devel("%s: qid %d, pid %d, addr %lx pg_off %lx sz %lu\n",
 711                         __func__, q_id, current->pid, vma->vm_start,
 712                         phys_off, (unsigned long)sz);
 713
 714         if (sz != ublk_queue_cmd_buf_size(ub, q_id))
 715                 return -EINVAL;
 716
 717         pfn = virt_to_phys(ublk_queue_cmd_buf(ub, q_id)) >> PAGE_SHIFT;
 718         return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
 719 }
 720
 721 static void ublk_commit_completion(struct ublk_device *ub,
 722                 struct ublksrv_io_cmd *ub_cmd)
 723 {
 724         u32 qid = ub_cmd->q_id, tag = ub_cmd->tag;
 725         struct ublk_queue *ubq = ublk_get_queue(ub, qid);
 726         struct ublk_io *io = &ubq->ios[tag];
 727         struct request *req;
 728
 729         /* now this cmd slot is owned by nbd driver */
 730         io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
 731         io->res = ub_cmd->result;
 732
 733         /* find the io request and complete */
 734         req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
 735
 736         if (req && likely(!blk_should_fake_timeout(req->q)))
 737                 ublk_complete_rq(req);
 738 }
 739
 740 /*
 741  * When ->ubq_daemon is exiting, either new request is ended immediately,
 742  * or any queued io command is drained, so it is safe to abort queue
 743  * lockless
 744  */
 745 static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
 746 {
 747         int i;
 748
 749         if (!ublk_get_device(ub))
 750                 return;
 751
 752         for (i = 0; i < ubq->q_depth; i++) {
 753                 struct ublk_io *io = &ubq->ios[i];
 754
 755                 if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) {
 756                         struct request *rq;
 757
 758                         /*
 759                          * Either we fail the request or ublk_rq_task_work_fn
 760                          * will do it
 761                          */
 762                         rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);
 763                         if (rq)
 764                                 __ublk_fail_req(io, rq);
 765                 }
 766         }
 767         ublk_put_device(ub);
 768 }
 769
 770 static void ublk_daemon_monitor_work(struct work_struct *work)
 771 {
 772         struct ublk_device *ub =
 773                 container_of(work, struct ublk_device, monitor_work.work);
 774         int i;
 775
 776         for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {
 777                 struct ublk_queue *ubq = ublk_get_queue(ub, i);
 778
 779                 if (ubq_daemon_is_dying(ubq)) {
 780                         schedule_work(&ub->stop_work);
 781
 782                         /* abort queue is for making forward progress */
 783                         ublk_abort_queue(ub, ubq);
 784                 }
 785         }
 786
 787         /*
 788          * We can't schedule monitor work after ublk_remove() is started.
 789          *
 790          * No need ub->mutex, monitor work are canceled after state is marked
 791          * as DEAD, so DEAD state is observed reliably.
 792          */
 793         if (ub->dev_info.state != UBLK_S_DEV_DEAD)
 794                 schedule_delayed_work(&ub->monitor_work,
 795                                 UBLK_DAEMON_MONITOR_PERIOD);
 796 }
 797
 798 static void ublk_cancel_queue(struct ublk_queue *ubq)
 799 {
 800         int i;
 801
 802         for (i = 0; i < ubq->q_depth; i++) {
 803                 struct ublk_io *io = &ubq->ios[i];
 804
 805                 if (io->flags & UBLK_IO_FLAG_ACTIVE)
 806                         io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0);
 807         }
 808 }
 809
 810 /* Cancel all pending commands, must be called after del_gendisk() returns */
 811 static void ublk_cancel_dev(struct ublk_device *ub)
 812 {
 813         int i;
 814
 815         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
 816                 ublk_cancel_queue(ublk_get_queue(ub, i));
 817 }
 818
 819 static void ublk_stop_dev(struct ublk_device *ub)
 820 {
 821         mutex_lock(&ub->mutex);
 822         if (!disk_live(ub->ub_disk))
 823                 goto unlock;
 824
 825         del_gendisk(ub->ub_disk);
 826         ub->dev_info.state = UBLK_S_DEV_DEAD;
 827         ub->dev_info.ublksrv_pid = -1;
 828         ublk_cancel_dev(ub);
 829  unlock:
 830         mutex_unlock(&ub->mutex);
 831         cancel_delayed_work_sync(&ub->monitor_work);
 832 }
 833
 834 static int ublk_ctrl_stop_dev(struct ublk_device *ub)
 835 {
 836         ublk_stop_dev(ub);
 837         cancel_work_sync(&ub->stop_work);
 838         return 0;
 839 }
 840
 841 static inline bool ublk_queue_ready(struct ublk_queue *ubq)
 842 {
 843         return ubq->nr_io_ready == ubq->q_depth;
 844 }
 845
 846 /* device can only be started after all IOs are ready */
 847 static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
 848 {
 849         mutex_lock(&ub->mutex);
 850         ubq->nr_io_ready++;
 851         if (ublk_queue_ready(ubq)) {
 852                 ubq->ubq_daemon = current;
 853                 get_task_struct(ubq->ubq_daemon);
 854                 ub->nr_queues_ready++;
 855         }
 856         if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
 857                 complete_all(&ub->completion);
 858         mutex_unlock(&ub->mutex);
 859 }
 860
 861 static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
 862 {
 863         struct ublksrv_io_cmd *ub_cmd = (struct ublksrv_io_cmd *)cmd->cmd;
 864         struct ublk_device *ub = cmd->file->private_data;
 865         struct ublk_queue *ubq;
 866         struct ublk_io *io;
 867         u32 cmd_op = cmd->cmd_op;
 868         unsigned tag = ub_cmd->tag;
 869         int ret = -EINVAL;
 870
 871         pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
 872                         __func__, cmd->cmd_op, ub_cmd->q_id, tag,
 873                         ub_cmd->result);
 874
 875         if (!(issue_flags & IO_URING_F_SQE128))
 876                 goto out;
 877
 878         if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues)
 879                 goto out;
 880
 881         ubq = ublk_get_queue(ub, ub_cmd->q_id);
 882         if (!ubq || ub_cmd->q_id != ubq->q_id)
 883                 goto out;
 884
 885         if (ubq->ubq_daemon && ubq->ubq_daemon != current)
 886                 goto out;
 887
 888         if (tag >= ubq->q_depth)
 889                 goto out;
 890
 891         io = &ubq->ios[tag];
 892
 893         /* there is pending io cmd, something must be wrong */
 894         if (io->flags & UBLK_IO_FLAG_ACTIVE) {
 895                 ret = -EBUSY;
 896                 goto out;
 897         }
 898
 899         switch (cmd_op) {
 900         case UBLK_IO_FETCH_REQ:
 901                 /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
 902                 if (ublk_queue_ready(ubq)) {
 903                         ret = -EBUSY;
 904                         goto out;
 905                 }
 906                 /*
 907                  * The io is being handled by server, so COMMIT_RQ is expected
 908                  * instead of FETCH_REQ
 909                  */
 910                 if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
 911                         goto out;
 912                 /* FETCH_RQ has to provide IO buffer */
 913                 if (!ub_cmd->addr)
 914                         goto out;
 915                 io->cmd = cmd;
 916                 io->flags |= UBLK_IO_FLAG_ACTIVE;
 917                 io->addr = ub_cmd->addr;
 918
 919                 ublk_mark_io_ready(ub, ubq);
 920                 break;
 921         case UBLK_IO_COMMIT_AND_FETCH_REQ:
 922                 /* FETCH_RQ has to provide IO buffer */
 923                 if (!ub_cmd->addr)
 924                         goto out;
 925                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
 926                         goto out;
 927                 io->addr = ub_cmd->addr;
 928                 io->flags |= UBLK_IO_FLAG_ACTIVE;
 929                 io->cmd = cmd;
 930                 ublk_commit_completion(ub, ub_cmd);
 931                 break;
 932         default:
 933                 goto out;
 934         }
 935         return -EIOCBQUEUED;
 936
 937  out:
 938         io->flags &= ~UBLK_IO_FLAG_ACTIVE;
 939         io_uring_cmd_done(cmd, ret, 0);
 940         pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n",
 941                         __func__, cmd_op, tag, ret, io->flags);
 942         return -EIOCBQUEUED;
 943 }
 944
 945 static const struct file_operations ublk_ch_fops = {
 946         .owner = THIS_MODULE,
 947         .open = ublk_ch_open,
 948         .release = ublk_ch_release,
 949         .llseek = no_llseek,
 950         .uring_cmd = ublk_ch_uring_cmd,
 951         .mmap = ublk_ch_mmap,
 952 };
 953
 954 static void ublk_deinit_queue(struct ublk_device *ub, int q_id)
 955 {
 956         int size = ublk_queue_cmd_buf_size(ub, q_id);
 957         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 958
 959         if (ubq->ubq_daemon)
 960                 put_task_struct(ubq->ubq_daemon);
 961         if (ubq->io_cmd_buf)
 962                 free_pages((unsigned long)ubq->io_cmd_buf, get_order(size));
 963 }
 964
 965 static int ublk_init_queue(struct ublk_device *ub, int q_id)
 966 {
 967         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 968         gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO;
 969         void *ptr;
 970         int size;
 971
 972         ubq->flags = ub->dev_info.flags[0];
 973         ubq->q_id = q_id;
 974         ubq->q_depth = ub->dev_info.queue_depth;
 975         size = ublk_queue_cmd_buf_size(ub, q_id);
 976
 977         ptr = (void *) __get_free_pages(gfp_flags, get_order(size));
 978         if (!ptr)
 979                 return -ENOMEM;
 980
 981         ubq->io_cmd_buf = ptr;
 982         ubq->dev = ub;
 983         return 0;
 984 }
 985
 986 static void ublk_deinit_queues(struct ublk_device *ub)
 987 {
 988         int nr_queues = ub->dev_info.nr_hw_queues;
 989         int i;
 990
 991         if (!ub->__queues)
 992                 return;
 993
 994         for (i = 0; i < nr_queues; i++)
 995                 ublk_deinit_queue(ub, i);
 996         kfree(ub->__queues);
 997 }
 998
 999 static int ublk_init_queues(struct ublk_device *ub)
1000 {
1001         int nr_queues = ub->dev_info.nr_hw_queues;
1002         int depth = ub->dev_info.queue_depth;
1003         int ubq_size = sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io);
1004         int i, ret = -ENOMEM;
1005
1006         ub->queue_size = ubq_size;
1007         ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL);
1008         if (!ub->__queues)
1009                 return ret;
1010
1011         for (i = 0; i < nr_queues; i++) {
1012                 if (ublk_init_queue(ub, i))
1013                         goto fail;
1014         }
1015
1016         init_completion(&ub->completion);
1017         return 0;
1018
1019  fail:
1020         ublk_deinit_queues(ub);
1021         return ret;
1022 }
1023
1024 static int __ublk_alloc_dev_number(struct ublk_device *ub, int idx)
1025 {
1026         int i = idx;
1027         int err;
1028
1029         spin_lock(&ublk_idr_lock);
1030         /* allocate id, if @id >= 0, we're requesting that specific id */
1031         if (i >= 0) {
1032                 err = idr_alloc(&ublk_index_idr, ub, i, i + 1, GFP_NOWAIT);
1033                 if (err == -ENOSPC)
1034                         err = -EEXIST;
1035         } else {
1036                 err = idr_alloc(&ublk_index_idr, ub, 0, 0, GFP_NOWAIT);
1037         }
1038         spin_unlock(&ublk_idr_lock);
1039
1040         if (err >= 0)
1041                 ub->ub_number = err;
1042
1043         return err;
1044 }
1045
1046 static struct ublk_device *__ublk_create_dev(int idx)
1047 {
1048         struct ublk_device *ub = NULL;
1049         int ret;
1050
1051         ub = kzalloc(sizeof(*ub), GFP_KERNEL);
1052         if (!ub)
1053                 return ERR_PTR(-ENOMEM);
1054
1055         ret = __ublk_alloc_dev_number(ub, idx);
1056         if (ret < 0) {
1057                 kfree(ub);
1058                 return ERR_PTR(ret);
1059         }
1060         return ub;
1061 }
1062
1063 static void __ublk_destroy_dev(struct ublk_device *ub)
1064 {
1065         spin_lock(&ublk_idr_lock);
1066         idr_remove(&ublk_index_idr, ub->ub_number);
1067         wake_up_all(&ublk_idr_wq);
1068         spin_unlock(&ublk_idr_lock);
1069
1070         mutex_destroy(&ub->mutex);
1071
1072         kfree(ub);
1073 }
1074
1075 static void ublk_cdev_rel(struct device *dev)
1076 {
1077         struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev);
1078
1079         put_disk(ub->ub_disk);
1080
1081         blk_mq_free_tag_set(&ub->tag_set);
1082
1083         ublk_deinit_queues(ub);
1084
1085         __ublk_destroy_dev(ub);
1086 }
1087
1088 static int ublk_add_chdev(struct ublk_device *ub)
1089 {
1090         struct device *dev = &ub->cdev_dev;
1091         int minor = ub->ub_number;
1092         int ret;
1093
1094         dev->parent = ublk_misc.this_device;
1095         dev->devt = MKDEV(MAJOR(ublk_chr_devt), minor);
1096         dev->class = ublk_chr_class;
1097         dev->release = ublk_cdev_rel;
1098         device_initialize(dev);
1099
1100         ret = dev_set_name(dev, "ublkc%d", minor);
1101         if (ret)
1102                 goto fail;
1103
1104         cdev_init(&ub->cdev, &ublk_ch_fops);
1105         ret = cdev_device_add(&ub->cdev, dev);
1106         if (ret)
1107                 goto fail;
1108         return 0;
1109  fail:
1110         put_device(dev);
1111         return ret;
1112 }
1113
1114 static void ublk_stop_work_fn(struct work_struct *work)
1115 {
1116         struct ublk_device *ub =
1117                 container_of(work, struct ublk_device, stop_work);
1118
1119         ublk_stop_dev(ub);
1120 }
1121
1122 static void ublk_update_capacity(struct ublk_device *ub)
1123 {
1124         unsigned int max_rq_bytes;
1125
1126         /* make max request buffer size aligned with PAGE_SIZE */
1127         max_rq_bytes = round_down(ub->dev_info.rq_max_blocks <<
1128                         ub->bs_shift, PAGE_SIZE);
1129         ub->dev_info.rq_max_blocks = max_rq_bytes >> ub->bs_shift;
1130
1131         set_capacity(ub->ub_disk, ub->dev_info.dev_blocks << (ub->bs_shift - 9));
1132 }
1133
1134 /* add disk & cdev, cleanup everything in case of failure */
1135 static int ublk_add_dev(struct ublk_device *ub)
1136 {
1137         struct gendisk *disk;
1138         int err = -ENOMEM;
1139         int bsize;
1140
1141         /* We are not ready to support zero copy */
1142         ub->dev_info.flags[0] &= ~UBLK_F_SUPPORT_ZERO_COPY;
1143
1144         bsize = ub->dev_info.block_size;
1145         ub->bs_shift = ilog2(bsize);
1146
1147         ub->dev_info.nr_hw_queues = min_t(unsigned int,
1148                         ub->dev_info.nr_hw_queues, nr_cpu_ids);
1149
1150         INIT_WORK(&ub->stop_work, ublk_stop_work_fn);
1151         INIT_DELAYED_WORK(&ub->monitor_work, ublk_daemon_monitor_work);
1152
1153         if (ublk_init_queues(ub))
1154                 goto out_destroy_dev;
1155
1156         ub->tag_set.ops = &ublk_mq_ops;
1157         ub->tag_set.nr_hw_queues = ub->dev_info.nr_hw_queues;
1158         ub->tag_set.queue_depth = ub->dev_info.queue_depth;
1159         ub->tag_set.numa_node = NUMA_NO_NODE;
1160         ub->tag_set.cmd_size = sizeof(struct ublk_rq_data);
1161         ub->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1162         ub->tag_set.driver_data = ub;
1163
1164         err = blk_mq_alloc_tag_set(&ub->tag_set);
1165         if (err)
1166                 goto out_deinit_queues;
1167
1168         disk = ub->ub_disk = blk_mq_alloc_disk(&ub->tag_set, ub);
1169         if (IS_ERR(disk)) {
1170                 err = PTR_ERR(disk);
1171                 goto out_cleanup_tags;
1172         }
1173         ub->ub_queue = ub->ub_disk->queue;
1174
1175         ub->ub_queue->queuedata = ub;
1176
1177         blk_queue_logical_block_size(ub->ub_queue, bsize);
1178         blk_queue_physical_block_size(ub->ub_queue, bsize);
1179         blk_queue_io_min(ub->ub_queue, bsize);
1180
1181         blk_queue_max_hw_sectors(ub->ub_queue, ub->dev_info.rq_max_blocks <<
1182                         (ub->bs_shift - 9));
1183
1184         ub->ub_queue->limits.discard_granularity = PAGE_SIZE;
1185
1186         blk_queue_max_discard_sectors(ub->ub_queue, UINT_MAX >> 9);
1187         blk_queue_max_write_zeroes_sectors(ub->ub_queue, UINT_MAX >> 9);
1188
1189         ublk_update_capacity(ub);
1190
1191         disk->fops              = &ub_fops;
1192         disk->private_data      = ub;
1193         disk->queue             = ub->ub_queue;
1194         sprintf(disk->disk_name, "ublkb%d", ub->ub_number);
1195
1196         mutex_init(&ub->mutex);
1197
1198         /* add char dev so that ublksrv daemon can be setup */
1199         err = ublk_add_chdev(ub);
1200         if (err)
1201                 return err;
1202
1203         /* don't expose disk now until we got start command from cdev */
1204
1205         return 0;
1206
1207 out_cleanup_tags:
1208         blk_mq_free_tag_set(&ub->tag_set);
1209 out_deinit_queues:
1210         ublk_deinit_queues(ub);
1211 out_destroy_dev:
1212         __ublk_destroy_dev(ub);
1213         return err;
1214 }
1215
1216 static void ublk_remove(struct ublk_device *ub)
1217 {
1218         ublk_ctrl_stop_dev(ub);
1219
1220         cdev_device_del(&ub->cdev, &ub->cdev_dev);
1221         put_device(&ub->cdev_dev);
1222 }
1223
1224 static struct ublk_device *ublk_get_device_from_id(int idx)
1225 {
1226         struct ublk_device *ub = NULL;
1227
1228         if (idx < 0)
1229                 return NULL;
1230
1231         spin_lock(&ublk_idr_lock);
1232         ub = idr_find(&ublk_index_idr, idx);
1233         if (ub)
1234                 ub = ublk_get_device(ub);
1235         spin_unlock(&ublk_idr_lock);
1236
1237         return ub;
1238 }
1239
1240 static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
1241 {
1242         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1243         int ret = -EINVAL;
1244         int ublksrv_pid = (int)header->data[0];
1245         unsigned long dev_blocks = header->data[1];
1246
1247         if (ublksrv_pid <= 0)
1248                 return ret;
1249
1250         wait_for_completion_interruptible(&ub->completion);
1251
1252         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
1253
1254         mutex_lock(&ub->mutex);
1255         if (!disk_live(ub->ub_disk)) {
1256                 /* We may get disk size updated */
1257                 if (dev_blocks) {
1258                         ub->dev_info.dev_blocks = dev_blocks;
1259                         ublk_update_capacity(ub);
1260                 }
1261                 ub->dev_info.ublksrv_pid = ublksrv_pid;
1262                 ret = add_disk(ub->ub_disk);
1263                 if (!ret)
1264                         ub->dev_info.state = UBLK_S_DEV_LIVE;
1265         } else {
1266                 ret = -EEXIST;
1267         }
1268         mutex_unlock(&ub->mutex);
1269
1270         return ret;
1271 }
1272
1273 static struct blk_mq_hw_ctx *ublk_get_hw_queue(struct ublk_device *ub,
1274                 unsigned int index)
1275 {
1276         struct blk_mq_hw_ctx *hctx;
1277         unsigned long i;
1278
1279         queue_for_each_hw_ctx(ub->ub_queue, hctx, i)
1280                 if (hctx->queue_num == index)
1281                         return hctx;
1282         return NULL;
1283 }
1284
1285 static int ublk_ctrl_get_queue_affinity(struct io_uring_cmd *cmd)
1286 {
1287         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1288         void __user *argp = (void __user *)(unsigned long)header->addr;
1289         struct blk_mq_hw_ctx *hctx;
1290         struct ublk_device *ub;
1291         unsigned long queue;
1292         unsigned int retlen;
1293         int ret;
1294
1295         ub = ublk_get_device_from_id(header->dev_id);
1296         if (!ub)
1297                 goto out;
1298
1299         ret = -EINVAL;
1300         queue = header->data[0];
1301         if (queue >= ub->dev_info.nr_hw_queues)
1302                 goto out;
1303         hctx = ublk_get_hw_queue(ub, queue);
1304         if (!hctx)
1305                 goto out;
1306
1307         retlen = min_t(unsigned short, header->len, cpumask_size());
1308         if (copy_to_user(argp, hctx->cpumask, retlen)) {
1309                 ret = -EFAULT;
1310                 goto out;
1311         }
1312         if (retlen != header->len) {
1313                 if (clear_user(argp + retlen, header->len - retlen)) {
1314                         ret = -EFAULT;
1315                         goto out;
1316                 }
1317         }
1318         ret = 0;
1319  out:
1320         if (ub)
1321                 ublk_put_device(ub);
1322         return ret;
1323 }
1324
1325 static int ublk_ctrl_add_dev(const struct ublksrv_ctrl_dev_info *info,
1326                 void __user *argp, int idx)
1327 {
1328         struct ublk_device *ub;
1329         int ret;
1330
1331         ret = mutex_lock_killable(&ublk_ctl_mutex);
1332         if (ret)
1333                 return ret;
1334
1335         ub = __ublk_create_dev(idx);
1336         if (!IS_ERR_OR_NULL(ub)) {
1337                 memcpy(&ub->dev_info, info, sizeof(*info));
1338
1339                 /* update device id */
1340                 ub->dev_info.dev_id = ub->ub_number;
1341
1342                 ret = ublk_add_dev(ub);
1343                 if (!ret) {
1344                         if (copy_to_user(argp, &ub->dev_info, sizeof(*info))) {
1345                                 ublk_remove(ub);
1346                                 ret = -EFAULT;
1347                         }
1348                 }
1349         } else {
1350                 if (IS_ERR(ub))
1351                         ret = PTR_ERR(ub);
1352                 else
1353                         ret = -ENOMEM;
1354         }
1355         mutex_unlock(&ublk_ctl_mutex);
1356
1357         return ret;
1358 }
1359
1360 static inline bool ublk_idr_freed(int id)
1361 {
1362         void *ptr;
1363
1364         spin_lock(&ublk_idr_lock);
1365         ptr = idr_find(&ublk_index_idr, id);
1366         spin_unlock(&ublk_idr_lock);
1367
1368         return ptr == NULL;
1369 }
1370
1371 static int ublk_ctrl_del_dev(int idx)
1372 {
1373         struct ublk_device *ub;
1374         int ret;
1375
1376         ret = mutex_lock_killable(&ublk_ctl_mutex);
1377         if (ret)
1378                 return ret;
1379
1380         ub = ublk_get_device_from_id(idx);
1381         if (ub) {
1382                 ublk_remove(ub);
1383                 ublk_put_device(ub);
1384                 ret = 0;
1385         } else {
1386                 ret = -ENODEV;
1387         }
1388
1389         /*
1390          * Wait until the idr is removed, then it can be reused after
1391          * DEL_DEV command is returned.
1392          */
1393         if (!ret)
1394                 wait_event(ublk_idr_wq, ublk_idr_freed(idx));
1395         mutex_unlock(&ublk_ctl_mutex);
1396
1397         return ret;
1398 }
1399
1400
1401 static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info)
1402 {
1403         pr_devel("%s: dev id %d flags %llx\n", __func__,
1404                         info->dev_id, info->flags[0]);
1405         pr_devel("\t nr_hw_queues %d queue_depth %d block size %d dev_capacity %lld\n",
1406                         info->nr_hw_queues, info->queue_depth,
1407                         info->block_size, info->dev_blocks);
1408 }
1409
1410 static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd)
1411 {
1412         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1413
1414         pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n",
1415                         __func__, cmd->cmd_op, header->dev_id, header->queue_id,
1416                         header->data[0], header->addr, header->len);
1417 }
1418
1419 static int ublk_ctrl_cmd_validate(struct io_uring_cmd *cmd,
1420                 struct ublksrv_ctrl_dev_info *info)
1421 {
1422         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1423         u32 cmd_op = cmd->cmd_op;
1424         void __user *argp = (void __user *)(unsigned long)header->addr;
1425
1426         if (!capable(CAP_SYS_ADMIN))
1427                 return -EPERM;
1428
1429         switch (cmd_op) {
1430         case UBLK_CMD_GET_DEV_INFO:
1431                 if (header->len < sizeof(*info) || !header->addr)
1432                         return -EINVAL;
1433                 break;
1434         case UBLK_CMD_ADD_DEV:
1435                 if (header->len < sizeof(*info) || !header->addr)
1436                         return -EINVAL;
1437                 if (copy_from_user(info, argp, sizeof(*info)) != 0)
1438                         return -EFAULT;
1439                 ublk_dump_dev_info(info);
1440                 if (header->dev_id != info->dev_id) {
1441                         printk(KERN_WARNING "%s: cmd %x, dev id not match %u %u\n",
1442                                         __func__, cmd_op, header->dev_id,
1443                                         info->dev_id);
1444                         return -EINVAL;
1445                 }
1446                 if (header->queue_id != (u16)-1) {
1447                         printk(KERN_WARNING "%s: cmd %x queue_id is wrong %x\n",
1448                                         __func__, cmd_op, header->queue_id);
1449                         return -EINVAL;
1450                 }
1451                 break;
1452         case UBLK_CMD_GET_QUEUE_AFFINITY:
1453                 if ((header->len * BITS_PER_BYTE) < nr_cpu_ids)
1454                         return -EINVAL;
1455                 if (header->len & (sizeof(unsigned long)-1))
1456                         return -EINVAL;
1457                 if (!header->addr)
1458                         return -EINVAL;
1459         };
1460
1461         return 0;
1462 }
1463
1464 static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
1465                 unsigned int issue_flags)
1466 {
1467         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1468         void __user *argp = (void __user *)(unsigned long)header->addr;
1469         struct ublksrv_ctrl_dev_info info;
1470         u32 cmd_op = cmd->cmd_op;
1471         struct ublk_device *ub;
1472         int ret = -EINVAL;
1473
1474         ublk_ctrl_cmd_dump(cmd);
1475
1476         if (!(issue_flags & IO_URING_F_SQE128))
1477                 goto out;
1478
1479         ret = ublk_ctrl_cmd_validate(cmd, &info);
1480         if (ret)
1481                 goto out;
1482
1483         ret = -ENODEV;
1484         switch (cmd_op) {
1485         case UBLK_CMD_START_DEV:
1486                 ub = ublk_get_device_from_id(header->dev_id);
1487                 if (ub) {
1488                         ret = ublk_ctrl_start_dev(ub, cmd);
1489                         ublk_put_device(ub);
1490                 }
1491                 break;
1492         case UBLK_CMD_STOP_DEV:
1493                 ub = ublk_get_device_from_id(header->dev_id);
1494                 if (ub) {
1495                         ret = ublk_ctrl_stop_dev(ub);
1496                         ublk_put_device(ub);
1497                 }
1498                 break;
1499         case UBLK_CMD_GET_DEV_INFO:
1500                 ub = ublk_get_device_from_id(header->dev_id);
1501                 if (ub) {
1502                         if (copy_to_user(argp, &ub->dev_info, sizeof(info)))
1503                                 ret = -EFAULT;
1504                         else
1505                                 ret = 0;
1506                         ublk_put_device(ub);
1507                 }
1508                 break;
1509         case UBLK_CMD_ADD_DEV:
1510                 ret = ublk_ctrl_add_dev(&info, argp, header->dev_id);
1511                 break;
1512         case UBLK_CMD_DEL_DEV:
1513                 ret = ublk_ctrl_del_dev(header->dev_id);
1514                 break;
1515         case UBLK_CMD_GET_QUEUE_AFFINITY:
1516                 ret = ublk_ctrl_get_queue_affinity(cmd);
1517                 break;
1518         default:
1519                 break;
1520         };
1521  out:
1522         io_uring_cmd_done(cmd, ret, 0);
1523         pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n",
1524                         __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id);
1525         return -EIOCBQUEUED;
1526 }
1527
1528 static const struct file_operations ublk_ctl_fops = {
1529         .open           = nonseekable_open,
1530         .uring_cmd      = ublk_ctrl_uring_cmd,
1531         .owner          = THIS_MODULE,
1532         .llseek         = noop_llseek,
1533 };
1534
1535 static struct miscdevice ublk_misc = {
1536         .minor          = MISC_DYNAMIC_MINOR,
1537         .name           = "ublk-control",
1538         .fops           = &ublk_ctl_fops,
1539 };
1540
1541 static int __init ublk_init(void)
1542 {
1543         int ret;
1544
1545         init_waitqueue_head(&ublk_idr_wq);
1546
1547         ret = misc_register(&ublk_misc);
1548         if (ret)
1549                 return ret;
1550
1551         ret = alloc_chrdev_region(&ublk_chr_devt, 0, UBLK_MINORS, "ublk-char");
1552         if (ret)
1553                 goto unregister_mis;
1554
1555         ublk_chr_class = class_create(THIS_MODULE, "ublk-char");
1556         if (IS_ERR(ublk_chr_class)) {
1557                 ret = PTR_ERR(ublk_chr_class);
1558                 goto free_chrdev_region;
1559         }
1560         return 0;
1561
1562 free_chrdev_region:
1563         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
1564 unregister_mis:
1565         misc_deregister(&ublk_misc);
1566         return ret;
1567 }
1568
1569 static void __exit ublk_exit(void)
1570 {
1571         struct ublk_device *ub;
1572         int id;
1573
1574         class_destroy(ublk_chr_class);
1575
1576         misc_deregister(&ublk_misc);
1577
1578         idr_for_each_entry(&ublk_index_idr, ub, id)
1579                 ublk_remove(ub);
1580
1581         idr_destroy(&ublk_index_idr);
1582         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
1583 }
1584
1585 module_init(ublk_init);
1586 module_exit(ublk_exit);
1587
1588 MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>");
1589 MODULE_LICENSE("GPL");