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
  54 /* All UBLK_PARAM_TYPE_* should be included here */
  55 #define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD)
  56
  57 struct ublk_rq_data {
  58         struct callback_head work;
  59 };
  60
  61 struct ublk_uring_cmd_pdu {
  62         struct request *req;
  63 };
  64
  65 /*
  66  * io command is active: sqe cmd is received, and its cqe isn't done
  67  *
  68  * If the flag is set, the io command is owned by ublk driver, and waited
  69  * for incoming blk-mq request from the ublk block device.
  70  *
  71  * If the flag is cleared, the io command will be completed, and owned by
  72  * ublk server.
  73  */
  74 #define UBLK_IO_FLAG_ACTIVE     0x01
  75
  76 /*
  77  * IO command is completed via cqe, and it is being handled by ublksrv, and
  78  * not committed yet
  79  *
  80  * Basically exclusively with UBLK_IO_FLAG_ACTIVE, so can be served for
  81  * cross verification
  82  */
  83 #define UBLK_IO_FLAG_OWNED_BY_SRV 0x02
  84
  85 /*
  86  * IO command is aborted, so this flag is set in case of
  87  * !UBLK_IO_FLAG_ACTIVE.
  88  *
  89  * After this flag is observed, any pending or new incoming request
  90  * associated with this io command will be failed immediately
  91  */
  92 #define UBLK_IO_FLAG_ABORTED 0x04
  93
  94 /*
  95  * UBLK_IO_FLAG_NEED_GET_DATA is set because IO command requires
  96  * get data buffer address from ublksrv.
  97  *
  98  * Then, bio data could be copied into this data buffer for a WRITE request
  99  * after the IO command is issued again and UBLK_IO_FLAG_NEED_GET_DATA is unset.
 100  */
 101 #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
 102
 103 struct ublk_io {
 104         /* userspace buffer address from io cmd */
 105         __u64   addr;
 106         unsigned int flags;
 107         int res;
 108
 109         struct io_uring_cmd *cmd;
 110 };
 111
 112 struct ublk_queue {
 113         int q_id;
 114         int q_depth;
 115
 116         unsigned long flags;
 117         struct task_struct      *ubq_daemon;
 118         char *io_cmd_buf;
 119
 120         unsigned long io_addr;  /* mapped vm address */
 121         unsigned int max_io_sz;
 122         bool abort_work_pending;
 123         unsigned short nr_io_ready;     /* how many ios setup */
 124         struct ublk_device *dev;
 125         struct ublk_io ios[0];
 126 };
 127
 128 #define UBLK_DAEMON_MONITOR_PERIOD      (5 * HZ)
 129
 130 struct ublk_device {
 131         struct gendisk          *ub_disk;
 132
 133         char    *__queues;
 134
 135         unsigned short  queue_size;
 136         struct ublksrv_ctrl_dev_info    dev_info;
 137
 138         struct blk_mq_tag_set   tag_set;
 139
 140         struct cdev             cdev;
 141         struct device           cdev_dev;
 142
 143 #define UB_STATE_OPEN           0
 144 #define UB_STATE_USED           1
 145         unsigned long           state;
 146         int                     ub_number;
 147
 148         struct mutex            mutex;
 149
 150         spinlock_t              mm_lock;
 151         struct mm_struct        *mm;
 152
 153         struct ublk_params      params;
 154
 155         struct completion       completion;
 156         unsigned int            nr_queues_ready;
 157         atomic_t                nr_aborted_queues;
 158
 159         /*
 160          * Our ubq->daemon may be killed without any notification, so
 161          * monitor each queue's daemon periodically
 162          */
 163         struct delayed_work     monitor_work;
 164         struct work_struct      stop_work;
 165 };
 166
 167 /* header of ublk_params */
 168 struct ublk_params_header {
 169         __u32   len;
 170         __u32   types;
 171 };
 172
 173 static dev_t ublk_chr_devt;
 174 static struct class *ublk_chr_class;
 175
 176 static DEFINE_IDR(ublk_index_idr);
 177 static DEFINE_SPINLOCK(ublk_idr_lock);
 178 static wait_queue_head_t ublk_idr_wq;   /* wait until one idr is freed */
 179
 180 static DEFINE_MUTEX(ublk_ctl_mutex);
 181
 182 static struct miscdevice ublk_misc;
 183
 184 static void ublk_dev_param_basic_apply(struct ublk_device *ub)
 185 {
 186         struct request_queue *q = ub->ub_disk->queue;
 187         const struct ublk_param_basic *p = &ub->params.basic;
 188
 189         blk_queue_logical_block_size(q, 1 << p->logical_bs_shift);
 190         blk_queue_physical_block_size(q, 1 << p->physical_bs_shift);
 191         blk_queue_io_min(q, 1 << p->io_min_shift);
 192         blk_queue_io_opt(q, 1 << p->io_opt_shift);
 193
 194         blk_queue_write_cache(q, p->attrs & UBLK_ATTR_VOLATILE_CACHE,
 195                         p->attrs & UBLK_ATTR_FUA);
 196         if (p->attrs & UBLK_ATTR_ROTATIONAL)
 197                 blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
 198         else
 199                 blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
 200
 201         blk_queue_max_hw_sectors(q, p->max_sectors);
 202         blk_queue_chunk_sectors(q, p->chunk_sectors);
 203         blk_queue_virt_boundary(q, p->virt_boundary_mask);
 204
 205         if (p->attrs & UBLK_ATTR_READ_ONLY)
 206                 set_disk_ro(ub->ub_disk, true);
 207
 208         set_capacity(ub->ub_disk, p->dev_sectors);
 209 }
 210
 211 static void ublk_dev_param_discard_apply(struct ublk_device *ub)
 212 {
 213         struct request_queue *q = ub->ub_disk->queue;
 214         const struct ublk_param_discard *p = &ub->params.discard;
 215
 216         q->limits.discard_alignment = p->discard_alignment;
 217         q->limits.discard_granularity = p->discard_granularity;
 218         blk_queue_max_discard_sectors(q, p->max_discard_sectors);
 219         blk_queue_max_write_zeroes_sectors(q,
 220                         p->max_write_zeroes_sectors);
 221         blk_queue_max_discard_segments(q, p->max_discard_segments);
 222 }
 223
 224 static int ublk_validate_params(const struct ublk_device *ub)
 225 {
 226         /* basic param is the only one which must be set */
 227         if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
 228                 const struct ublk_param_basic *p = &ub->params.basic;
 229
 230                 if (p->logical_bs_shift > PAGE_SHIFT)
 231                         return -EINVAL;
 232
 233                 if (p->logical_bs_shift > p->physical_bs_shift)
 234                         return -EINVAL;
 235
 236                 if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
 237                         return -EINVAL;
 238         } else
 239                 return -EINVAL;
 240
 241         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD) {
 242                 const struct ublk_param_discard *p = &ub->params.discard;
 243
 244                 /* So far, only support single segment discard */
 245                 if (p->max_discard_sectors && p->max_discard_segments != 1)
 246                         return -EINVAL;
 247
 248                 if (!p->discard_granularity)
 249                         return -EINVAL;
 250         }
 251
 252         return 0;
 253 }
 254
 255 static int ublk_apply_params(struct ublk_device *ub)
 256 {
 257         if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
 258                 return -EINVAL;
 259
 260         ublk_dev_param_basic_apply(ub);
 261
 262         if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
 263                 ublk_dev_param_discard_apply(ub);
 264
 265         return 0;
 266 }
 267
 268 static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq)
 269 {
 270         if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) &&
 271                         !(ubq->flags & UBLK_F_URING_CMD_COMP_IN_TASK))
 272                 return true;
 273         return false;
 274 }
 275
 276 static inline bool ublk_need_get_data(const struct ublk_queue *ubq)
 277 {
 278         if (ubq->flags & UBLK_F_NEED_GET_DATA)
 279                 return true;
 280         return false;
 281 }
 282
 283 static struct ublk_device *ublk_get_device(struct ublk_device *ub)
 284 {
 285         if (kobject_get_unless_zero(&ub->cdev_dev.kobj))
 286                 return ub;
 287         return NULL;
 288 }
 289
 290 static void ublk_put_device(struct ublk_device *ub)
 291 {
 292         put_device(&ub->cdev_dev);
 293 }
 294
 295 static inline struct ublk_queue *ublk_get_queue(struct ublk_device *dev,
 296                 int qid)
 297 {
 298        return (struct ublk_queue *)&(dev->__queues[qid * dev->queue_size]);
 299 }
 300
 301 static inline bool ublk_rq_has_data(const struct request *rq)
 302 {
 303         return rq->bio && bio_has_data(rq->bio);
 304 }
 305
 306 static inline struct ublksrv_io_desc *ublk_get_iod(struct ublk_queue *ubq,
 307                 int tag)
 308 {
 309         return (struct ublksrv_io_desc *)
 310                 &(ubq->io_cmd_buf[tag * sizeof(struct ublksrv_io_desc)]);
 311 }
 312
 313 static inline char *ublk_queue_cmd_buf(struct ublk_device *ub, int q_id)
 314 {
 315         return ublk_get_queue(ub, q_id)->io_cmd_buf;
 316 }
 317
 318 static inline int ublk_queue_cmd_buf_size(struct ublk_device *ub, int q_id)
 319 {
 320         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
 321
 322         return round_up(ubq->q_depth * sizeof(struct ublksrv_io_desc),
 323                         PAGE_SIZE);
 324 }
 325
 326 static void ublk_free_disk(struct gendisk *disk)
 327 {
 328         struct ublk_device *ub = disk->private_data;
 329
 330         clear_bit(UB_STATE_USED, &ub->state);
 331         put_device(&ub->cdev_dev);
 332 }
 333
 334 static const struct block_device_operations ub_fops = {
 335         .owner =        THIS_MODULE,
 336         .free_disk =    ublk_free_disk,
 337 };
 338
 339 #define UBLK_MAX_PIN_PAGES      32
 340
 341 struct ublk_map_data {
 342         const struct ublk_queue *ubq;
 343         const struct request *rq;
 344         const struct ublk_io *io;
 345         unsigned max_bytes;
 346 };
 347
 348 struct ublk_io_iter {
 349         struct page *pages[UBLK_MAX_PIN_PAGES];
 350         unsigned pg_off;        /* offset in the 1st page in pages */
 351         int nr_pages;           /* how many page pointers in pages */
 352         struct bio *bio;
 353         struct bvec_iter iter;
 354 };
 355
 356 static inline unsigned ublk_copy_io_pages(struct ublk_io_iter *data,
 357                 unsigned max_bytes, bool to_vm)
 358 {
 359         const unsigned total = min_t(unsigned, max_bytes,
 360                         PAGE_SIZE - data->pg_off +
 361                         ((data->nr_pages - 1) << PAGE_SHIFT));
 362         unsigned done = 0;
 363         unsigned pg_idx = 0;
 364
 365         while (done < total) {
 366                 struct bio_vec bv = bio_iter_iovec(data->bio, data->iter);
 367                 const unsigned int bytes = min3(bv.bv_len, total - done,
 368                                 (unsigned)(PAGE_SIZE - data->pg_off));
 369                 void *bv_buf = bvec_kmap_local(&bv);
 370                 void *pg_buf = kmap_local_page(data->pages[pg_idx]);
 371
 372                 if (to_vm)
 373                         memcpy(pg_buf + data->pg_off, bv_buf, bytes);
 374                 else
 375                         memcpy(bv_buf, pg_buf + data->pg_off, bytes);
 376
 377                 kunmap_local(pg_buf);
 378                 kunmap_local(bv_buf);
 379
 380                 /* advance page array */
 381                 data->pg_off += bytes;
 382                 if (data->pg_off == PAGE_SIZE) {
 383                         pg_idx += 1;
 384                         data->pg_off = 0;
 385                 }
 386
 387                 done += bytes;
 388
 389                 /* advance bio */
 390                 bio_advance_iter_single(data->bio, &data->iter, bytes);
 391                 if (!data->iter.bi_size) {
 392                         data->bio = data->bio->bi_next;
 393                         if (data->bio == NULL)
 394                                 break;
 395                         data->iter = data->bio->bi_iter;
 396                 }
 397         }
 398
 399         return done;
 400 }
 401
 402 static inline int ublk_copy_user_pages(struct ublk_map_data *data,
 403                 bool to_vm)
 404 {
 405         const unsigned int gup_flags = to_vm ? FOLL_WRITE : 0;
 406         const unsigned long start_vm = data->io->addr;
 407         unsigned int done = 0;
 408         struct ublk_io_iter iter = {
 409                 .pg_off = start_vm & (PAGE_SIZE - 1),
 410                 .bio    = data->rq->bio,
 411                 .iter   = data->rq->bio->bi_iter,
 412         };
 413         const unsigned int nr_pages = round_up(data->max_bytes +
 414                         (start_vm & (PAGE_SIZE - 1)), PAGE_SIZE) >> PAGE_SHIFT;
 415
 416         while (done < nr_pages) {
 417                 const unsigned to_pin = min_t(unsigned, UBLK_MAX_PIN_PAGES,
 418                                 nr_pages - done);
 419                 unsigned i, len;
 420
 421                 iter.nr_pages = get_user_pages_fast(start_vm +
 422                                 (done << PAGE_SHIFT), to_pin, gup_flags,
 423                                 iter.pages);
 424                 if (iter.nr_pages <= 0)
 425                         return done == 0 ? iter.nr_pages : done;
 426                 len = ublk_copy_io_pages(&iter, data->max_bytes, to_vm);
 427                 for (i = 0; i < iter.nr_pages; i++) {
 428                         if (to_vm)
 429                                 set_page_dirty(iter.pages[i]);
 430                         put_page(iter.pages[i]);
 431                 }
 432                 data->max_bytes -= len;
 433                 done += iter.nr_pages;
 434         }
 435
 436         return done;
 437 }
 438
 439 static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
 440                 struct ublk_io *io)
 441 {
 442         const unsigned int rq_bytes = blk_rq_bytes(req);
 443         /*
 444          * no zero copy, we delay copy WRITE request data into ublksrv
 445          * context and the big benefit is that pinning pages in current
 446          * context is pretty fast, see ublk_pin_user_pages
 447          */
 448         if (req_op(req) != REQ_OP_WRITE && req_op(req) != REQ_OP_FLUSH)
 449                 return rq_bytes;
 450
 451         if (ublk_rq_has_data(req)) {
 452                 struct ublk_map_data data = {
 453                         .ubq    =       ubq,
 454                         .rq     =       req,
 455                         .io     =       io,
 456                         .max_bytes =    rq_bytes,
 457                 };
 458
 459                 ublk_copy_user_pages(&data, true);
 460
 461                 return rq_bytes - data.max_bytes;
 462         }
 463         return rq_bytes;
 464 }
 465
 466 static int ublk_unmap_io(const struct ublk_queue *ubq,
 467                 const struct request *req,
 468                 struct ublk_io *io)
 469 {
 470         const unsigned int rq_bytes = blk_rq_bytes(req);
 471
 472         if (req_op(req) == REQ_OP_READ && ublk_rq_has_data(req)) {
 473                 struct ublk_map_data data = {
 474                         .ubq    =       ubq,
 475                         .rq     =       req,
 476                         .io     =       io,
 477                         .max_bytes =    io->res,
 478                 };
 479
 480                 WARN_ON_ONCE(io->res > rq_bytes);
 481
 482                 ublk_copy_user_pages(&data, false);
 483
 484                 return io->res - data.max_bytes;
 485         }
 486         return rq_bytes;
 487 }
 488
 489 static inline unsigned int ublk_req_build_flags(struct request *req)
 490 {
 491         unsigned flags = 0;
 492
 493         if (req->cmd_flags & REQ_FAILFAST_DEV)
 494                 flags |= UBLK_IO_F_FAILFAST_DEV;
 495
 496         if (req->cmd_flags & REQ_FAILFAST_TRANSPORT)
 497                 flags |= UBLK_IO_F_FAILFAST_TRANSPORT;
 498
 499         if (req->cmd_flags & REQ_FAILFAST_DRIVER)
 500                 flags |= UBLK_IO_F_FAILFAST_DRIVER;
 501
 502         if (req->cmd_flags & REQ_META)
 503                 flags |= UBLK_IO_F_META;
 504
 505         if (req->cmd_flags & REQ_FUA)
 506                 flags |= UBLK_IO_F_FUA;
 507
 508         if (req->cmd_flags & REQ_NOUNMAP)
 509                 flags |= UBLK_IO_F_NOUNMAP;
 510
 511         if (req->cmd_flags & REQ_SWAP)
 512                 flags |= UBLK_IO_F_SWAP;
 513
 514         return flags;
 515 }
 516
 517 static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 518 {
 519         struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
 520         struct ublk_io *io = &ubq->ios[req->tag];
 521         u32 ublk_op;
 522
 523         switch (req_op(req)) {
 524         case REQ_OP_READ:
 525                 ublk_op = UBLK_IO_OP_READ;
 526                 break;
 527         case REQ_OP_WRITE:
 528                 ublk_op = UBLK_IO_OP_WRITE;
 529                 break;
 530         case REQ_OP_FLUSH:
 531                 ublk_op = UBLK_IO_OP_FLUSH;
 532                 break;
 533         case REQ_OP_DISCARD:
 534                 ublk_op = UBLK_IO_OP_DISCARD;
 535                 break;
 536         case REQ_OP_WRITE_ZEROES:
 537                 ublk_op = UBLK_IO_OP_WRITE_ZEROES;
 538                 break;
 539         default:
 540                 return BLK_STS_IOERR;
 541         }
 542
 543         /* need to translate since kernel may change */
 544         iod->op_flags = ublk_op | ublk_req_build_flags(req);
 545         iod->nr_sectors = blk_rq_sectors(req);
 546         iod->start_sector = blk_rq_pos(req);
 547         iod->addr = io->addr;
 548
 549         return BLK_STS_OK;
 550 }
 551
 552 static inline struct ublk_uring_cmd_pdu *ublk_get_uring_cmd_pdu(
 553                 struct io_uring_cmd *ioucmd)
 554 {
 555         return (struct ublk_uring_cmd_pdu *)&ioucmd->pdu;
 556 }
 557
 558 static bool ubq_daemon_is_dying(struct ublk_queue *ubq)
 559 {
 560         return ubq->ubq_daemon->flags & PF_EXITING;
 561 }
 562
 563 /* todo: handle partial completion */
 564 static void ublk_complete_rq(struct request *req)
 565 {
 566         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 567         struct ublk_io *io = &ubq->ios[req->tag];
 568         unsigned int unmapped_bytes;
 569
 570         /* failed read IO if nothing is read */
 571         if (!io->res && req_op(req) == REQ_OP_READ)
 572                 io->res = -EIO;
 573
 574         if (io->res < 0) {
 575                 blk_mq_end_request(req, errno_to_blk_status(io->res));
 576                 return;
 577         }
 578
 579         /*
 580          * FLUSH or DISCARD usually won't return bytes returned, so end them
 581          * directly.
 582          *
 583          * Both the two needn't unmap.
 584          */
 585         if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE) {
 586                 blk_mq_end_request(req, BLK_STS_OK);
 587                 return;
 588         }
 589
 590         /* for READ request, writing data in iod->addr to rq buffers */
 591         unmapped_bytes = ublk_unmap_io(ubq, req, io);
 592
 593         /*
 594          * Extremely impossible since we got data filled in just before
 595          *
 596          * Re-read simply for this unlikely case.
 597          */
 598         if (unlikely(unmapped_bytes < io->res))
 599                 io->res = unmapped_bytes;
 600
 601         if (blk_update_request(req, BLK_STS_OK, io->res))
 602                 blk_mq_requeue_request(req, true);
 603         else
 604                 __blk_mq_end_request(req, BLK_STS_OK);
 605 }
 606
 607 /*
 608  * __ublk_fail_req() may be called from abort context or ->ubq_daemon
 609  * context during exiting, so lock is required.
 610  *
 611  * Also aborting may not be started yet, keep in mind that one failed
 612  * request may be issued by block layer again.
 613  */
 614 static void __ublk_fail_req(struct ublk_io *io, struct request *req)
 615 {
 616         WARN_ON_ONCE(io->flags & UBLK_IO_FLAG_ACTIVE);
 617
 618         if (!(io->flags & UBLK_IO_FLAG_ABORTED)) {
 619                 io->flags |= UBLK_IO_FLAG_ABORTED;
 620                 blk_mq_end_request(req, BLK_STS_IOERR);
 621         }
 622 }
 623
 624 static void ubq_complete_io_cmd(struct ublk_io *io, int res)
 625 {
 626         /* mark this cmd owned by ublksrv */
 627         io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV;
 628
 629         /*
 630          * clear ACTIVE since we are done with this sqe/cmd slot
 631          * We can only accept io cmd in case of being not active.
 632          */
 633         io->flags &= ~UBLK_IO_FLAG_ACTIVE;
 634
 635         /* tell ublksrv one io request is coming */
 636         io_uring_cmd_done(io->cmd, res, 0);
 637 }
 638
 639 #define UBLK_REQUEUE_DELAY_MS   3
 640
 641 static inline void __ublk_rq_task_work(struct request *req)
 642 {
 643         struct ublk_queue *ubq = req->mq_hctx->driver_data;
 644         struct ublk_device *ub = ubq->dev;
 645         int tag = req->tag;
 646         struct ublk_io *io = &ubq->ios[tag];
 647         bool task_exiting = current != ubq->ubq_daemon ||
 648                 (current->flags & PF_EXITING);
 649         unsigned int mapped_bytes;
 650
 651         pr_devel("%s: complete: op %d, qid %d tag %d io_flags %x addr %llx\n",
 652                         __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags,
 653                         ublk_get_iod(ubq, req->tag)->addr);
 654
 655         if (unlikely(task_exiting)) {
 656                 blk_mq_end_request(req, BLK_STS_IOERR);
 657                 mod_delayed_work(system_wq, &ub->monitor_work, 0);
 658                 return;
 659         }
 660
 661         if (ublk_need_get_data(ubq) &&
 662                         (req_op(req) == REQ_OP_WRITE ||
 663                         req_op(req) == REQ_OP_FLUSH)) {
 664                 /*
 665                  * We have not handled UBLK_IO_NEED_GET_DATA command yet,
 666                  * so immepdately pass UBLK_IO_RES_NEED_GET_DATA to ublksrv
 667                  * and notify it.
 668                  */
 669                 if (!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA)) {
 670                         io->flags |= UBLK_IO_FLAG_NEED_GET_DATA;
 671                         pr_devel("%s: need get data. op %d, qid %d tag %d io_flags %x\n",
 672                                         __func__, io->cmd->cmd_op, ubq->q_id,
 673                                         req->tag, io->flags);
 674                         ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA);
 675                         return;
 676                 }
 677                 /*
 678                  * We have handled UBLK_IO_NEED_GET_DATA command,
 679                  * so clear UBLK_IO_FLAG_NEED_GET_DATA now and just
 680                  * do the copy work.
 681                  */
 682                 io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA;
 683         }
 684
 685         mapped_bytes = ublk_map_io(ubq, req, io);
 686
 687         /* partially mapped, update io descriptor */
 688         if (unlikely(mapped_bytes != blk_rq_bytes(req))) {
 689                 /*
 690                  * Nothing mapped, retry until we succeed.
 691                  *
 692                  * We may never succeed in mapping any bytes here because
 693                  * of OOM. TODO: reserve one buffer with single page pinned
 694                  * for providing forward progress guarantee.
 695                  */
 696                 if (unlikely(!mapped_bytes)) {
 697                         blk_mq_requeue_request(req, false);
 698                         blk_mq_delay_kick_requeue_list(req->q,
 699                                         UBLK_REQUEUE_DELAY_MS);
 700                         return;
 701                 }
 702
 703                 ublk_get_iod(ubq, req->tag)->nr_sectors =
 704                         mapped_bytes >> 9;
 705         }
 706
 707         ubq_complete_io_cmd(io, UBLK_IO_RES_OK);
 708 }
 709
 710 static void ublk_rq_task_work_cb(struct io_uring_cmd *cmd)
 711 {
 712         struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 713
 714         __ublk_rq_task_work(pdu->req);
 715 }
 716
 717 static void ublk_rq_task_work_fn(struct callback_head *work)
 718 {
 719         struct ublk_rq_data *data = container_of(work,
 720                         struct ublk_rq_data, work);
 721         struct request *req = blk_mq_rq_from_pdu(data);
 722
 723         __ublk_rq_task_work(req);
 724 }
 725
 726 static blk_status_t ublk_queue_rq(struct blk_mq_hw_ctx *hctx,
 727                 const struct blk_mq_queue_data *bd)
 728 {
 729         struct ublk_queue *ubq = hctx->driver_data;
 730         struct request *rq = bd->rq;
 731         blk_status_t res;
 732
 733         /* fill iod to slot in io cmd buffer */
 734         res = ublk_setup_iod(ubq, rq);
 735         if (unlikely(res != BLK_STS_OK))
 736                 return BLK_STS_IOERR;
 737
 738         blk_mq_start_request(bd->rq);
 739
 740         if (unlikely(ubq_daemon_is_dying(ubq))) {
 741  fail:
 742                 mod_delayed_work(system_wq, &ubq->dev->monitor_work, 0);
 743                 return BLK_STS_IOERR;
 744         }
 745
 746         if (ublk_can_use_task_work(ubq)) {
 747                 struct ublk_rq_data *data = blk_mq_rq_to_pdu(rq);
 748                 enum task_work_notify_mode notify_mode = bd->last ?
 749                         TWA_SIGNAL_NO_IPI : TWA_NONE;
 750
 751                 if (task_work_add(ubq->ubq_daemon, &data->work, notify_mode))
 752                         goto fail;
 753         } else {
 754                 struct io_uring_cmd *cmd = ubq->ios[rq->tag].cmd;
 755                 struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
 756
 757                 pdu->req = rq;
 758                 io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb);
 759         }
 760
 761         return BLK_STS_OK;
 762 }
 763
 764 static void ublk_commit_rqs(struct blk_mq_hw_ctx *hctx)
 765 {
 766         struct ublk_queue *ubq = hctx->driver_data;
 767
 768         if (ublk_can_use_task_work(ubq))
 769                 __set_notify_signal(ubq->ubq_daemon);
 770 }
 771
 772 static int ublk_init_hctx(struct blk_mq_hw_ctx *hctx, void *driver_data,
 773                 unsigned int hctx_idx)
 774 {
 775         struct ublk_device *ub = driver_data;
 776         struct ublk_queue *ubq = ublk_get_queue(ub, hctx->queue_num);
 777
 778         hctx->driver_data = ubq;
 779         return 0;
 780 }
 781
 782 static int ublk_init_rq(struct blk_mq_tag_set *set, struct request *req,
 783                 unsigned int hctx_idx, unsigned int numa_node)
 784 {
 785         struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
 786
 787         init_task_work(&data->work, ublk_rq_task_work_fn);
 788         return 0;
 789 }
 790
 791 static const struct blk_mq_ops ublk_mq_ops = {
 792         .queue_rq       = ublk_queue_rq,
 793         .commit_rqs     = ublk_commit_rqs,
 794         .init_hctx      = ublk_init_hctx,
 795         .init_request   = ublk_init_rq,
 796 };
 797
 798 static int ublk_ch_open(struct inode *inode, struct file *filp)
 799 {
 800         struct ublk_device *ub = container_of(inode->i_cdev,
 801                         struct ublk_device, cdev);
 802
 803         if (test_and_set_bit(UB_STATE_OPEN, &ub->state))
 804                 return -EBUSY;
 805         filp->private_data = ub;
 806         return 0;
 807 }
 808
 809 static int ublk_ch_release(struct inode *inode, struct file *filp)
 810 {
 811         struct ublk_device *ub = filp->private_data;
 812
 813         clear_bit(UB_STATE_OPEN, &ub->state);
 814         return 0;
 815 }
 816
 817 /* map pre-allocated per-queue cmd buffer to ublksrv daemon */
 818 static int ublk_ch_mmap(struct file *filp, struct vm_area_struct *vma)
 819 {
 820         struct ublk_device *ub = filp->private_data;
 821         size_t sz = vma->vm_end - vma->vm_start;
 822         unsigned max_sz = UBLK_MAX_QUEUE_DEPTH * sizeof(struct ublksrv_io_desc);
 823         unsigned long pfn, end, phys_off = vma->vm_pgoff << PAGE_SHIFT;
 824         int q_id, ret = 0;
 825
 826         spin_lock(&ub->mm_lock);
 827         if (!ub->mm)
 828                 ub->mm = current->mm;
 829         if (current->mm != ub->mm)
 830                 ret = -EINVAL;
 831         spin_unlock(&ub->mm_lock);
 832
 833         if (ret)
 834                 return ret;
 835
 836         if (vma->vm_flags & VM_WRITE)
 837                 return -EPERM;
 838
 839         end = UBLKSRV_CMD_BUF_OFFSET + ub->dev_info.nr_hw_queues * max_sz;
 840         if (phys_off < UBLKSRV_CMD_BUF_OFFSET || phys_off >= end)
 841                 return -EINVAL;
 842
 843         q_id = (phys_off - UBLKSRV_CMD_BUF_OFFSET) / max_sz;
 844         pr_devel("%s: qid %d, pid %d, addr %lx pg_off %lx sz %lu\n",
 845                         __func__, q_id, current->pid, vma->vm_start,
 846                         phys_off, (unsigned long)sz);
 847
 848         if (sz != ublk_queue_cmd_buf_size(ub, q_id))
 849                 return -EINVAL;
 850
 851         pfn = virt_to_phys(ublk_queue_cmd_buf(ub, q_id)) >> PAGE_SHIFT;
 852         return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
 853 }
 854
 855 static void ublk_commit_completion(struct ublk_device *ub,
 856                 struct ublksrv_io_cmd *ub_cmd)
 857 {
 858         u32 qid = ub_cmd->q_id, tag = ub_cmd->tag;
 859         struct ublk_queue *ubq = ublk_get_queue(ub, qid);
 860         struct ublk_io *io = &ubq->ios[tag];
 861         struct request *req;
 862
 863         /* now this cmd slot is owned by nbd driver */
 864         io->flags &= ~UBLK_IO_FLAG_OWNED_BY_SRV;
 865         io->res = ub_cmd->result;
 866
 867         /* find the io request and complete */
 868         req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
 869
 870         if (req && likely(!blk_should_fake_timeout(req->q)))
 871                 ublk_complete_rq(req);
 872 }
 873
 874 /*
 875  * When ->ubq_daemon is exiting, either new request is ended immediately,
 876  * or any queued io command is drained, so it is safe to abort queue
 877  * lockless
 878  */
 879 static void ublk_abort_queue(struct ublk_device *ub, struct ublk_queue *ubq)
 880 {
 881         int i;
 882
 883         if (!ublk_get_device(ub))
 884                 return;
 885
 886         for (i = 0; i < ubq->q_depth; i++) {
 887                 struct ublk_io *io = &ubq->ios[i];
 888
 889                 if (!(io->flags & UBLK_IO_FLAG_ACTIVE)) {
 890                         struct request *rq;
 891
 892                         /*
 893                          * Either we fail the request or ublk_rq_task_work_fn
 894                          * will do it
 895                          */
 896                         rq = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], i);
 897                         if (rq)
 898                                 __ublk_fail_req(io, rq);
 899                 }
 900         }
 901         ublk_put_device(ub);
 902 }
 903
 904 static void ublk_daemon_monitor_work(struct work_struct *work)
 905 {
 906         struct ublk_device *ub =
 907                 container_of(work, struct ublk_device, monitor_work.work);
 908         int i;
 909
 910         for (i = 0; i < ub->dev_info.nr_hw_queues; i++) {
 911                 struct ublk_queue *ubq = ublk_get_queue(ub, i);
 912
 913                 if (ubq_daemon_is_dying(ubq)) {
 914                         schedule_work(&ub->stop_work);
 915
 916                         /* abort queue is for making forward progress */
 917                         ublk_abort_queue(ub, ubq);
 918                 }
 919         }
 920
 921         /*
 922          * We can't schedule monitor work after ublk_remove() is started.
 923          *
 924          * No need ub->mutex, monitor work are canceled after state is marked
 925          * as DEAD, so DEAD state is observed reliably.
 926          */
 927         if (ub->dev_info.state != UBLK_S_DEV_DEAD)
 928                 schedule_delayed_work(&ub->monitor_work,
 929                                 UBLK_DAEMON_MONITOR_PERIOD);
 930 }
 931
 932 static inline bool ublk_queue_ready(struct ublk_queue *ubq)
 933 {
 934         return ubq->nr_io_ready == ubq->q_depth;
 935 }
 936
 937 static void ublk_cancel_queue(struct ublk_queue *ubq)
 938 {
 939         int i;
 940
 941         if (!ublk_queue_ready(ubq))
 942                 return;
 943
 944         for (i = 0; i < ubq->q_depth; i++) {
 945                 struct ublk_io *io = &ubq->ios[i];
 946
 947                 if (io->flags & UBLK_IO_FLAG_ACTIVE)
 948                         io_uring_cmd_done(io->cmd, UBLK_IO_RES_ABORT, 0);
 949         }
 950
 951         /* all io commands are canceled */
 952         ubq->nr_io_ready = 0;
 953 }
 954
 955 /* Cancel all pending commands, must be called after del_gendisk() returns */
 956 static void ublk_cancel_dev(struct ublk_device *ub)
 957 {
 958         int i;
 959
 960         for (i = 0; i < ub->dev_info.nr_hw_queues; i++)
 961                 ublk_cancel_queue(ublk_get_queue(ub, i));
 962 }
 963
 964 static void ublk_stop_dev(struct ublk_device *ub)
 965 {
 966         mutex_lock(&ub->mutex);
 967         if (ub->dev_info.state != UBLK_S_DEV_LIVE)
 968                 goto unlock;
 969
 970         del_gendisk(ub->ub_disk);
 971         ub->dev_info.state = UBLK_S_DEV_DEAD;
 972         ub->dev_info.ublksrv_pid = -1;
 973         put_disk(ub->ub_disk);
 974         ub->ub_disk = NULL;
 975  unlock:
 976         ublk_cancel_dev(ub);
 977         mutex_unlock(&ub->mutex);
 978         cancel_delayed_work_sync(&ub->monitor_work);
 979 }
 980
 981 /* device can only be started after all IOs are ready */
 982 static void ublk_mark_io_ready(struct ublk_device *ub, struct ublk_queue *ubq)
 983 {
 984         mutex_lock(&ub->mutex);
 985         ubq->nr_io_ready++;
 986         if (ublk_queue_ready(ubq)) {
 987                 ubq->ubq_daemon = current;
 988                 get_task_struct(ubq->ubq_daemon);
 989                 ub->nr_queues_ready++;
 990         }
 991         if (ub->nr_queues_ready == ub->dev_info.nr_hw_queues)
 992                 complete_all(&ub->completion);
 993         mutex_unlock(&ub->mutex);
 994 }
 995
 996 static void ublk_handle_need_get_data(struct ublk_device *ub, int q_id,
 997                 int tag, struct io_uring_cmd *cmd)
 998 {
 999         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1000         struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[q_id], tag);
1001
1002         if (ublk_can_use_task_work(ubq)) {
1003                 struct ublk_rq_data *data = blk_mq_rq_to_pdu(req);
1004
1005                 /* should not fail since we call it just in ubq->ubq_daemon */
1006                 task_work_add(ubq->ubq_daemon, &data->work, TWA_SIGNAL_NO_IPI);
1007         } else {
1008                 struct ublk_uring_cmd_pdu *pdu = ublk_get_uring_cmd_pdu(cmd);
1009
1010                 pdu->req = req;
1011                 io_uring_cmd_complete_in_task(cmd, ublk_rq_task_work_cb);
1012         }
1013 }
1014
1015 static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags)
1016 {
1017         struct ublksrv_io_cmd *ub_cmd = (struct ublksrv_io_cmd *)cmd->cmd;
1018         struct ublk_device *ub = cmd->file->private_data;
1019         struct ublk_queue *ubq;
1020         struct ublk_io *io;
1021         u32 cmd_op = cmd->cmd_op;
1022         unsigned tag = ub_cmd->tag;
1023         int ret = -EINVAL;
1024
1025         pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
1026                         __func__, cmd->cmd_op, ub_cmd->q_id, tag,
1027                         ub_cmd->result);
1028
1029         if (!(issue_flags & IO_URING_F_SQE128))
1030                 goto out;
1031
1032         if (ub_cmd->q_id >= ub->dev_info.nr_hw_queues)
1033                 goto out;
1034
1035         ubq = ublk_get_queue(ub, ub_cmd->q_id);
1036         if (!ubq || ub_cmd->q_id != ubq->q_id)
1037                 goto out;
1038
1039         if (ubq->ubq_daemon && ubq->ubq_daemon != current)
1040                 goto out;
1041
1042         if (tag >= ubq->q_depth)
1043                 goto out;
1044
1045         io = &ubq->ios[tag];
1046
1047         /* there is pending io cmd, something must be wrong */
1048         if (io->flags & UBLK_IO_FLAG_ACTIVE) {
1049                 ret = -EBUSY;
1050                 goto out;
1051         }
1052
1053         /*
1054          * ensure that the user issues UBLK_IO_NEED_GET_DATA
1055          * iff the driver have set the UBLK_IO_FLAG_NEED_GET_DATA.
1056          */
1057         if ((!!(io->flags & UBLK_IO_FLAG_NEED_GET_DATA))
1058                         ^ (cmd_op == UBLK_IO_NEED_GET_DATA))
1059                 goto out;
1060
1061         switch (cmd_op) {
1062         case UBLK_IO_FETCH_REQ:
1063                 /* UBLK_IO_FETCH_REQ is only allowed before queue is setup */
1064                 if (ublk_queue_ready(ubq)) {
1065                         ret = -EBUSY;
1066                         goto out;
1067                 }
1068                 /*
1069                  * The io is being handled by server, so COMMIT_RQ is expected
1070                  * instead of FETCH_REQ
1071                  */
1072                 if (io->flags & UBLK_IO_FLAG_OWNED_BY_SRV)
1073                         goto out;
1074                 /* FETCH_RQ has to provide IO buffer */
1075                 if (!ub_cmd->addr)
1076                         goto out;
1077                 io->cmd = cmd;
1078                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1079                 io->addr = ub_cmd->addr;
1080
1081                 ublk_mark_io_ready(ub, ubq);
1082                 break;
1083         case UBLK_IO_COMMIT_AND_FETCH_REQ:
1084                 /* FETCH_RQ has to provide IO buffer */
1085                 if (!ub_cmd->addr)
1086                         goto out;
1087                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1088                         goto out;
1089                 io->addr = ub_cmd->addr;
1090                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1091                 io->cmd = cmd;
1092                 ublk_commit_completion(ub, ub_cmd);
1093                 break;
1094         case UBLK_IO_NEED_GET_DATA:
1095                 if (!(io->flags & UBLK_IO_FLAG_OWNED_BY_SRV))
1096                         goto out;
1097                 io->addr = ub_cmd->addr;
1098                 io->cmd = cmd;
1099                 io->flags |= UBLK_IO_FLAG_ACTIVE;
1100                 ublk_handle_need_get_data(ub, ub_cmd->q_id, ub_cmd->tag, cmd);
1101                 break;
1102         default:
1103                 goto out;
1104         }
1105         return -EIOCBQUEUED;
1106
1107  out:
1108         io_uring_cmd_done(cmd, ret, 0);
1109         pr_devel("%s: complete: cmd op %d, tag %d ret %x io_flags %x\n",
1110                         __func__, cmd_op, tag, ret, io->flags);
1111         return -EIOCBQUEUED;
1112 }
1113
1114 static const struct file_operations ublk_ch_fops = {
1115         .owner = THIS_MODULE,
1116         .open = ublk_ch_open,
1117         .release = ublk_ch_release,
1118         .llseek = no_llseek,
1119         .uring_cmd = ublk_ch_uring_cmd,
1120         .mmap = ublk_ch_mmap,
1121 };
1122
1123 static void ublk_deinit_queue(struct ublk_device *ub, int q_id)
1124 {
1125         int size = ublk_queue_cmd_buf_size(ub, q_id);
1126         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1127
1128         if (ubq->ubq_daemon)
1129                 put_task_struct(ubq->ubq_daemon);
1130         if (ubq->io_cmd_buf)
1131                 free_pages((unsigned long)ubq->io_cmd_buf, get_order(size));
1132 }
1133
1134 static int ublk_init_queue(struct ublk_device *ub, int q_id)
1135 {
1136         struct ublk_queue *ubq = ublk_get_queue(ub, q_id);
1137         gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO;
1138         void *ptr;
1139         int size;
1140
1141         ubq->flags = ub->dev_info.flags;
1142         ubq->q_id = q_id;
1143         ubq->q_depth = ub->dev_info.queue_depth;
1144         size = ublk_queue_cmd_buf_size(ub, q_id);
1145
1146         ptr = (void *) __get_free_pages(gfp_flags, get_order(size));
1147         if (!ptr)
1148                 return -ENOMEM;
1149
1150         ubq->io_cmd_buf = ptr;
1151         ubq->dev = ub;
1152         return 0;
1153 }
1154
1155 static void ublk_deinit_queues(struct ublk_device *ub)
1156 {
1157         int nr_queues = ub->dev_info.nr_hw_queues;
1158         int i;
1159
1160         if (!ub->__queues)
1161                 return;
1162
1163         for (i = 0; i < nr_queues; i++)
1164                 ublk_deinit_queue(ub, i);
1165         kfree(ub->__queues);
1166 }
1167
1168 static int ublk_init_queues(struct ublk_device *ub)
1169 {
1170         int nr_queues = ub->dev_info.nr_hw_queues;
1171         int depth = ub->dev_info.queue_depth;
1172         int ubq_size = sizeof(struct ublk_queue) + depth * sizeof(struct ublk_io);
1173         int i, ret = -ENOMEM;
1174
1175         ub->queue_size = ubq_size;
1176         ub->__queues = kcalloc(nr_queues, ubq_size, GFP_KERNEL);
1177         if (!ub->__queues)
1178                 return ret;
1179
1180         for (i = 0; i < nr_queues; i++) {
1181                 if (ublk_init_queue(ub, i))
1182                         goto fail;
1183         }
1184
1185         init_completion(&ub->completion);
1186         return 0;
1187
1188  fail:
1189         ublk_deinit_queues(ub);
1190         return ret;
1191 }
1192
1193 static int ublk_alloc_dev_number(struct ublk_device *ub, int idx)
1194 {
1195         int i = idx;
1196         int err;
1197
1198         spin_lock(&ublk_idr_lock);
1199         /* allocate id, if @id >= 0, we're requesting that specific id */
1200         if (i >= 0) {
1201                 err = idr_alloc(&ublk_index_idr, ub, i, i + 1, GFP_NOWAIT);
1202                 if (err == -ENOSPC)
1203                         err = -EEXIST;
1204         } else {
1205                 err = idr_alloc(&ublk_index_idr, ub, 0, 0, GFP_NOWAIT);
1206         }
1207         spin_unlock(&ublk_idr_lock);
1208
1209         if (err >= 0)
1210                 ub->ub_number = err;
1211
1212         return err;
1213 }
1214
1215 static void ublk_free_dev_number(struct ublk_device *ub)
1216 {
1217         spin_lock(&ublk_idr_lock);
1218         idr_remove(&ublk_index_idr, ub->ub_number);
1219         wake_up_all(&ublk_idr_wq);
1220         spin_unlock(&ublk_idr_lock);
1221 }
1222
1223 static void ublk_cdev_rel(struct device *dev)
1224 {
1225         struct ublk_device *ub = container_of(dev, struct ublk_device, cdev_dev);
1226
1227         blk_mq_free_tag_set(&ub->tag_set);
1228         ublk_deinit_queues(ub);
1229         ublk_free_dev_number(ub);
1230         mutex_destroy(&ub->mutex);
1231         kfree(ub);
1232 }
1233
1234 static int ublk_add_chdev(struct ublk_device *ub)
1235 {
1236         struct device *dev = &ub->cdev_dev;
1237         int minor = ub->ub_number;
1238         int ret;
1239
1240         dev->parent = ublk_misc.this_device;
1241         dev->devt = MKDEV(MAJOR(ublk_chr_devt), minor);
1242         dev->class = ublk_chr_class;
1243         dev->release = ublk_cdev_rel;
1244         device_initialize(dev);
1245
1246         ret = dev_set_name(dev, "ublkc%d", minor);
1247         if (ret)
1248                 goto fail;
1249
1250         cdev_init(&ub->cdev, &ublk_ch_fops);
1251         ret = cdev_device_add(&ub->cdev, dev);
1252         if (ret)
1253                 goto fail;
1254         return 0;
1255  fail:
1256         put_device(dev);
1257         return ret;
1258 }
1259
1260 static void ublk_stop_work_fn(struct work_struct *work)
1261 {
1262         struct ublk_device *ub =
1263                 container_of(work, struct ublk_device, stop_work);
1264
1265         ublk_stop_dev(ub);
1266 }
1267
1268 /* align max io buffer size with PAGE_SIZE */
1269 static void ublk_align_max_io_size(struct ublk_device *ub)
1270 {
1271         unsigned int max_io_bytes = ub->dev_info.max_io_buf_bytes;
1272
1273         ub->dev_info.max_io_buf_bytes =
1274                 round_down(max_io_bytes, PAGE_SIZE);
1275 }
1276
1277 static int ublk_add_tag_set(struct ublk_device *ub)
1278 {
1279         ub->tag_set.ops = &ublk_mq_ops;
1280         ub->tag_set.nr_hw_queues = ub->dev_info.nr_hw_queues;
1281         ub->tag_set.queue_depth = ub->dev_info.queue_depth;
1282         ub->tag_set.numa_node = NUMA_NO_NODE;
1283         ub->tag_set.cmd_size = sizeof(struct ublk_rq_data);
1284         ub->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1285         ub->tag_set.driver_data = ub;
1286         return blk_mq_alloc_tag_set(&ub->tag_set);
1287 }
1288
1289 static void ublk_remove(struct ublk_device *ub)
1290 {
1291         ublk_stop_dev(ub);
1292         cancel_work_sync(&ub->stop_work);
1293         cdev_device_del(&ub->cdev, &ub->cdev_dev);
1294         put_device(&ub->cdev_dev);
1295 }
1296
1297 static struct ublk_device *ublk_get_device_from_id(int idx)
1298 {
1299         struct ublk_device *ub = NULL;
1300
1301         if (idx < 0)
1302                 return NULL;
1303
1304         spin_lock(&ublk_idr_lock);
1305         ub = idr_find(&ublk_index_idr, idx);
1306         if (ub)
1307                 ub = ublk_get_device(ub);
1308         spin_unlock(&ublk_idr_lock);
1309
1310         return ub;
1311 }
1312
1313 static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
1314 {
1315         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1316         int ublksrv_pid = (int)header->data[0];
1317         struct ublk_device *ub;
1318         struct gendisk *disk;
1319         int ret = -EINVAL;
1320
1321         if (ublksrv_pid <= 0)
1322                 return -EINVAL;
1323
1324         ub = ublk_get_device_from_id(header->dev_id);
1325         if (!ub)
1326                 return -EINVAL;
1327
1328         wait_for_completion_interruptible(&ub->completion);
1329
1330         schedule_delayed_work(&ub->monitor_work, UBLK_DAEMON_MONITOR_PERIOD);
1331
1332         mutex_lock(&ub->mutex);
1333         if (ub->dev_info.state == UBLK_S_DEV_LIVE ||
1334             test_bit(UB_STATE_USED, &ub->state)) {
1335                 ret = -EEXIST;
1336                 goto out_unlock;
1337         }
1338
1339         disk = blk_mq_alloc_disk(&ub->tag_set, ub);
1340         if (IS_ERR(disk)) {
1341                 ret = PTR_ERR(disk);
1342                 goto out_unlock;
1343         }
1344         sprintf(disk->disk_name, "ublkb%d", ub->ub_number);
1345         disk->fops = &ub_fops;
1346         disk->private_data = ub;
1347
1348         ub->dev_info.ublksrv_pid = ublksrv_pid;
1349         ub->ub_disk = disk;
1350
1351         ret = ublk_apply_params(ub);
1352         if (ret)
1353                 goto out_put_disk;
1354
1355         get_device(&ub->cdev_dev);
1356         ret = add_disk(disk);
1357         if (ret) {
1358                 /*
1359                  * Has to drop the reference since ->free_disk won't be
1360                  * called in case of add_disk failure.
1361                  */
1362                 ublk_put_device(ub);
1363                 goto out_put_disk;
1364         }
1365         set_bit(UB_STATE_USED, &ub->state);
1366         ub->dev_info.state = UBLK_S_DEV_LIVE;
1367 out_put_disk:
1368         if (ret)
1369                 put_disk(disk);
1370 out_unlock:
1371         mutex_unlock(&ub->mutex);
1372         ublk_put_device(ub);
1373         return ret;
1374 }
1375
1376 static int ublk_ctrl_get_queue_affinity(struct io_uring_cmd *cmd)
1377 {
1378         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1379         void __user *argp = (void __user *)(unsigned long)header->addr;
1380         struct ublk_device *ub;
1381         cpumask_var_t cpumask;
1382         unsigned long queue;
1383         unsigned int retlen;
1384         unsigned int i;
1385         int ret = -EINVAL;
1386
1387         if (header->len * BITS_PER_BYTE < nr_cpu_ids)
1388                 return -EINVAL;
1389         if (header->len & (sizeof(unsigned long)-1))
1390                 return -EINVAL;
1391         if (!header->addr)
1392                 return -EINVAL;
1393
1394         ub = ublk_get_device_from_id(header->dev_id);
1395         if (!ub)
1396                 return -EINVAL;
1397
1398         queue = header->data[0];
1399         if (queue >= ub->dev_info.nr_hw_queues)
1400                 goto out_put_device;
1401
1402         ret = -ENOMEM;
1403         if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
1404                 goto out_put_device;
1405
1406         for_each_possible_cpu(i) {
1407                 if (ub->tag_set.map[HCTX_TYPE_DEFAULT].mq_map[i] == queue)
1408                         cpumask_set_cpu(i, cpumask);
1409         }
1410
1411         ret = -EFAULT;
1412         retlen = min_t(unsigned short, header->len, cpumask_size());
1413         if (copy_to_user(argp, cpumask, retlen))
1414                 goto out_free_cpumask;
1415         if (retlen != header->len &&
1416             clear_user(argp + retlen, header->len - retlen))
1417                 goto out_free_cpumask;
1418
1419         ret = 0;
1420 out_free_cpumask:
1421         free_cpumask_var(cpumask);
1422 out_put_device:
1423         ublk_put_device(ub);
1424         return ret;
1425 }
1426
1427 static inline void ublk_dump_dev_info(struct ublksrv_ctrl_dev_info *info)
1428 {
1429         pr_devel("%s: dev id %d flags %llx\n", __func__,
1430                         info->dev_id, info->flags);
1431         pr_devel("\t nr_hw_queues %d queue_depth %d\n",
1432                         info->nr_hw_queues, info->queue_depth);
1433 }
1434
1435 static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
1436 {
1437         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1438         void __user *argp = (void __user *)(unsigned long)header->addr;
1439         struct ublksrv_ctrl_dev_info info;
1440         struct ublk_device *ub;
1441         int ret = -EINVAL;
1442
1443         if (header->len < sizeof(info) || !header->addr)
1444                 return -EINVAL;
1445         if (header->queue_id != (u16)-1) {
1446                 pr_warn("%s: queue_id is wrong %x\n",
1447                         __func__, header->queue_id);
1448                 return -EINVAL;
1449         }
1450         if (copy_from_user(&info, argp, sizeof(info)))
1451                 return -EFAULT;
1452         ublk_dump_dev_info(&info);
1453         if (header->dev_id != info.dev_id) {
1454                 pr_warn("%s: dev id not match %u %u\n",
1455                         __func__, header->dev_id, info.dev_id);
1456                 return -EINVAL;
1457         }
1458
1459         ret = mutex_lock_killable(&ublk_ctl_mutex);
1460         if (ret)
1461                 return ret;
1462
1463         ret = -ENOMEM;
1464         ub = kzalloc(sizeof(*ub), GFP_KERNEL);
1465         if (!ub)
1466                 goto out_unlock;
1467         mutex_init(&ub->mutex);
1468         spin_lock_init(&ub->mm_lock);
1469         INIT_WORK(&ub->stop_work, ublk_stop_work_fn);
1470         INIT_DELAYED_WORK(&ub->monitor_work, ublk_daemon_monitor_work);
1471
1472         ret = ublk_alloc_dev_number(ub, header->dev_id);
1473         if (ret < 0)
1474                 goto out_free_ub;
1475
1476         memcpy(&ub->dev_info, &info, sizeof(info));
1477
1478         /* update device id */
1479         ub->dev_info.dev_id = ub->ub_number;
1480
1481         /*
1482          * 64bit flags will be copied back to userspace as feature
1483          * negotiation result, so have to clear flags which driver
1484          * doesn't support yet, then userspace can get correct flags
1485          * (features) to handle.
1486          */
1487         ub->dev_info.flags &= UBLK_F_ALL;
1488
1489         /* We are not ready to support zero copy */
1490         ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
1491
1492         ub->dev_info.nr_hw_queues = min_t(unsigned int,
1493                         ub->dev_info.nr_hw_queues, nr_cpu_ids);
1494         ublk_align_max_io_size(ub);
1495
1496         ret = ublk_init_queues(ub);
1497         if (ret)
1498                 goto out_free_dev_number;
1499
1500         ret = ublk_add_tag_set(ub);
1501         if (ret)
1502                 goto out_deinit_queues;
1503
1504         ret = -EFAULT;
1505         if (copy_to_user(argp, &ub->dev_info, sizeof(info)))
1506                 goto out_free_tag_set;
1507
1508         /*
1509          * Add the char dev so that ublksrv daemon can be setup.
1510          * ublk_add_chdev() will cleanup everything if it fails.
1511          */
1512         ret = ublk_add_chdev(ub);
1513         goto out_unlock;
1514
1515 out_free_tag_set:
1516         blk_mq_free_tag_set(&ub->tag_set);
1517 out_deinit_queues:
1518         ublk_deinit_queues(ub);
1519 out_free_dev_number:
1520         ublk_free_dev_number(ub);
1521 out_free_ub:
1522         mutex_destroy(&ub->mutex);
1523         kfree(ub);
1524 out_unlock:
1525         mutex_unlock(&ublk_ctl_mutex);
1526         return ret;
1527 }
1528
1529 static inline bool ublk_idr_freed(int id)
1530 {
1531         void *ptr;
1532
1533         spin_lock(&ublk_idr_lock);
1534         ptr = idr_find(&ublk_index_idr, id);
1535         spin_unlock(&ublk_idr_lock);
1536
1537         return ptr == NULL;
1538 }
1539
1540 static int ublk_ctrl_del_dev(int idx)
1541 {
1542         struct ublk_device *ub;
1543         int ret;
1544
1545         ret = mutex_lock_killable(&ublk_ctl_mutex);
1546         if (ret)
1547                 return ret;
1548
1549         ub = ublk_get_device_from_id(idx);
1550         if (ub) {
1551                 ublk_remove(ub);
1552                 ublk_put_device(ub);
1553                 ret = 0;
1554         } else {
1555                 ret = -ENODEV;
1556         }
1557
1558         /*
1559          * Wait until the idr is removed, then it can be reused after
1560          * DEL_DEV command is returned.
1561          */
1562         if (!ret)
1563                 wait_event(ublk_idr_wq, ublk_idr_freed(idx));
1564         mutex_unlock(&ublk_ctl_mutex);
1565
1566         return ret;
1567 }
1568
1569 static inline void ublk_ctrl_cmd_dump(struct io_uring_cmd *cmd)
1570 {
1571         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1572
1573         pr_devel("%s: cmd_op %x, dev id %d qid %d data %llx buf %llx len %u\n",
1574                         __func__, cmd->cmd_op, header->dev_id, header->queue_id,
1575                         header->data[0], header->addr, header->len);
1576 }
1577
1578 static int ublk_ctrl_stop_dev(struct io_uring_cmd *cmd)
1579 {
1580         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1581         struct ublk_device *ub;
1582
1583         ub = ublk_get_device_from_id(header->dev_id);
1584         if (!ub)
1585                 return -EINVAL;
1586
1587         ublk_stop_dev(ub);
1588         cancel_work_sync(&ub->stop_work);
1589
1590         ublk_put_device(ub);
1591         return 0;
1592 }
1593
1594 static int ublk_ctrl_get_dev_info(struct io_uring_cmd *cmd)
1595 {
1596         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1597         void __user *argp = (void __user *)(unsigned long)header->addr;
1598         struct ublk_device *ub;
1599         int ret = 0;
1600
1601         if (header->len < sizeof(struct ublksrv_ctrl_dev_info) || !header->addr)
1602                 return -EINVAL;
1603
1604         ub = ublk_get_device_from_id(header->dev_id);
1605         if (!ub)
1606                 return -EINVAL;
1607
1608         if (copy_to_user(argp, &ub->dev_info, sizeof(ub->dev_info)))
1609                 ret = -EFAULT;
1610         ublk_put_device(ub);
1611
1612         return ret;
1613 }
1614
1615 static int ublk_ctrl_get_params(struct io_uring_cmd *cmd)
1616 {
1617         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1618         void __user *argp = (void __user *)(unsigned long)header->addr;
1619         struct ublk_params_header ph;
1620         struct ublk_device *ub;
1621         int ret;
1622
1623         if (header->len <= sizeof(ph) || !header->addr)
1624                 return -EINVAL;
1625
1626         if (copy_from_user(&ph, argp, sizeof(ph)))
1627                 return -EFAULT;
1628
1629         if (ph.len > header->len || !ph.len)
1630                 return -EINVAL;
1631
1632         if (ph.len > sizeof(struct ublk_params))
1633                 ph.len = sizeof(struct ublk_params);
1634
1635         ub = ublk_get_device_from_id(header->dev_id);
1636         if (!ub)
1637                 return -EINVAL;
1638
1639         mutex_lock(&ub->mutex);
1640         if (copy_to_user(argp, &ub->params, ph.len))
1641                 ret = -EFAULT;
1642         else
1643                 ret = 0;
1644         mutex_unlock(&ub->mutex);
1645
1646         ublk_put_device(ub);
1647         return ret;
1648 }
1649
1650 static int ublk_ctrl_set_params(struct io_uring_cmd *cmd)
1651 {
1652         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1653         void __user *argp = (void __user *)(unsigned long)header->addr;
1654         struct ublk_params_header ph;
1655         struct ublk_device *ub;
1656         int ret = -EFAULT;
1657
1658         if (header->len <= sizeof(ph) || !header->addr)
1659                 return -EINVAL;
1660
1661         if (copy_from_user(&ph, argp, sizeof(ph)))
1662                 return -EFAULT;
1663
1664         if (ph.len > header->len || !ph.len || !ph.types)
1665                 return -EINVAL;
1666
1667         if (ph.len > sizeof(struct ublk_params))
1668                 ph.len = sizeof(struct ublk_params);
1669
1670         ub = ublk_get_device_from_id(header->dev_id);
1671         if (!ub)
1672                 return -EINVAL;
1673
1674         /* parameters can only be changed when device isn't live */
1675         mutex_lock(&ub->mutex);
1676         if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
1677                 ret = -EACCES;
1678         } else if (copy_from_user(&ub->params, argp, ph.len)) {
1679                 ret = -EFAULT;
1680         } else {
1681                 /* clear all we don't support yet */
1682                 ub->params.types &= UBLK_PARAM_TYPE_ALL;
1683                 ret = ublk_validate_params(ub);
1684         }
1685         mutex_unlock(&ub->mutex);
1686         ublk_put_device(ub);
1687
1688         return ret;
1689 }
1690
1691 static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
1692                 unsigned int issue_flags)
1693 {
1694         struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
1695         int ret = -EINVAL;
1696
1697         ublk_ctrl_cmd_dump(cmd);
1698
1699         if (!(issue_flags & IO_URING_F_SQE128))
1700                 goto out;
1701
1702         ret = -EPERM;
1703         if (!capable(CAP_SYS_ADMIN))
1704                 goto out;
1705
1706         ret = -ENODEV;
1707         switch (cmd->cmd_op) {
1708         case UBLK_CMD_START_DEV:
1709                 ret = ublk_ctrl_start_dev(cmd);
1710                 break;
1711         case UBLK_CMD_STOP_DEV:
1712                 ret = ublk_ctrl_stop_dev(cmd);
1713                 break;
1714         case UBLK_CMD_GET_DEV_INFO:
1715                 ret = ublk_ctrl_get_dev_info(cmd);
1716                 break;
1717         case UBLK_CMD_ADD_DEV:
1718                 ret = ublk_ctrl_add_dev(cmd);
1719                 break;
1720         case UBLK_CMD_DEL_DEV:
1721                 ret = ublk_ctrl_del_dev(header->dev_id);
1722                 break;
1723         case UBLK_CMD_GET_QUEUE_AFFINITY:
1724                 ret = ublk_ctrl_get_queue_affinity(cmd);
1725                 break;
1726         case UBLK_CMD_GET_PARAMS:
1727                 ret = ublk_ctrl_get_params(cmd);
1728                 break;
1729         case UBLK_CMD_SET_PARAMS:
1730                 ret = ublk_ctrl_set_params(cmd);
1731                 break;
1732         default:
1733                 break;
1734         }
1735  out:
1736         io_uring_cmd_done(cmd, ret, 0);
1737         pr_devel("%s: cmd done ret %d cmd_op %x, dev id %d qid %d\n",
1738                         __func__, ret, cmd->cmd_op, header->dev_id, header->queue_id);
1739         return -EIOCBQUEUED;
1740 }
1741
1742 static const struct file_operations ublk_ctl_fops = {
1743         .open           = nonseekable_open,
1744         .uring_cmd      = ublk_ctrl_uring_cmd,
1745         .owner          = THIS_MODULE,
1746         .llseek         = noop_llseek,
1747 };
1748
1749 static struct miscdevice ublk_misc = {
1750         .minor          = MISC_DYNAMIC_MINOR,
1751         .name           = "ublk-control",
1752         .fops           = &ublk_ctl_fops,
1753 };
1754
1755 static int __init ublk_init(void)
1756 {
1757         int ret;
1758
1759         init_waitqueue_head(&ublk_idr_wq);
1760
1761         ret = misc_register(&ublk_misc);
1762         if (ret)
1763                 return ret;
1764
1765         ret = alloc_chrdev_region(&ublk_chr_devt, 0, UBLK_MINORS, "ublk-char");
1766         if (ret)
1767                 goto unregister_mis;
1768
1769         ublk_chr_class = class_create(THIS_MODULE, "ublk-char");
1770         if (IS_ERR(ublk_chr_class)) {
1771                 ret = PTR_ERR(ublk_chr_class);
1772                 goto free_chrdev_region;
1773         }
1774         return 0;
1775
1776 free_chrdev_region:
1777         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
1778 unregister_mis:
1779         misc_deregister(&ublk_misc);
1780         return ret;
1781 }
1782
1783 static void __exit ublk_exit(void)
1784 {
1785         struct ublk_device *ub;
1786         int id;
1787
1788         class_destroy(ublk_chr_class);
1789
1790         misc_deregister(&ublk_misc);
1791
1792         idr_for_each_entry(&ublk_index_idr, ub, id)
1793                 ublk_remove(ub);
1794
1795         idr_destroy(&ublk_index_idr);
1796         unregister_chrdev_region(ublk_chr_devt, UBLK_MINORS);
1797 }
1798
1799 module_init(ublk_init);
1800 module_exit(ublk_exit);
1801
1802 MODULE_AUTHOR("Ming Lei <ming.lei@redhat.com>");
1803 MODULE_LICENSE("GPL");