io_uring/rsrc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/kernel.h>
   3 #include <linux/errno.h>
   4 #include <linux/fs.h>
   5 #include <linux/file.h>
   6 #include <linux/mm.h>
   7 #include <linux/slab.h>
   8 #include <linux/nospec.h>
   9 #include <linux/hugetlb.h>
  10 #include <linux/compat.h>
  11 #include <linux/io_uring.h>
  12
  13 #include <uapi/linux/io_uring.h>
  14
  15 #include "io_uring.h"
  16 #include "openclose.h"
  17 #include "rsrc.h"
  18 #include "notif.h"
  19
  20 struct io_rsrc_update {
  21         struct file                     *file;
  22         u64                             arg;
  23         u32                             nr_args;
  24         u32                             offset;
  25         int                             type;
  26 };
  27
  28 static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
  29                                   struct io_mapped_ubuf **pimu,
  30                                   struct page **last_hpage);
  31
  32 #define IO_RSRC_REF_BATCH       100
  33
  34 /* only define max */
  35 #define IORING_MAX_FIXED_FILES  (1U << 20)
  36 #define IORING_MAX_REG_BUFFERS  (1U << 14)
  37
  38 void io_rsrc_refs_drop(struct io_ring_ctx *ctx)
  39         __must_hold(&ctx->uring_lock)
  40 {
  41         if (ctx->rsrc_cached_refs) {
  42                 io_rsrc_put_node(ctx->rsrc_node, ctx->rsrc_cached_refs);
  43                 ctx->rsrc_cached_refs = 0;
  44         }
  45 }
  46
  47 int __io_account_mem(struct user_struct *user, unsigned long nr_pages)
  48 {
  49         unsigned long page_limit, cur_pages, new_pages;
  50
  51         if (!nr_pages)
  52                 return 0;
  53
  54         /* Don't allow more pages than we can safely lock */
  55         page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
  56
  57         cur_pages = atomic_long_read(&user->locked_vm);
  58         do {
  59                 new_pages = cur_pages + nr_pages;
  60                 if (new_pages > page_limit)
  61                         return -ENOMEM;
  62         } while (!atomic_long_try_cmpxchg(&user->locked_vm,
  63                                           &cur_pages, new_pages));
  64         return 0;
  65 }
  66
  67 static void io_unaccount_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
  68 {
  69         if (ctx->user)
  70                 __io_unaccount_mem(ctx->user, nr_pages);
  71
  72         if (ctx->mm_account)
  73                 atomic64_sub(nr_pages, &ctx->mm_account->pinned_vm);
  74 }
  75
  76 static int io_account_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
  77 {
  78         int ret;
  79
  80         if (ctx->user) {
  81                 ret = __io_account_mem(ctx->user, nr_pages);
  82                 if (ret)
  83                         return ret;
  84         }
  85
  86         if (ctx->mm_account)
  87                 atomic64_add(nr_pages, &ctx->mm_account->pinned_vm);
  88
  89         return 0;
  90 }
  91
  92 static int io_copy_iov(struct io_ring_ctx *ctx, struct iovec *dst,
  93                        void __user *arg, unsigned index)
  94 {
  95         struct iovec __user *src;
  96
  97 #ifdef CONFIG_COMPAT
  98         if (ctx->compat) {
  99                 struct compat_iovec __user *ciovs;
 100                 struct compat_iovec ciov;
 101
 102                 ciovs = (struct compat_iovec __user *) arg;
 103                 if (copy_from_user(&ciov, &ciovs[index], sizeof(ciov)))
 104                         return -EFAULT;
 105
 106                 dst->iov_base = u64_to_user_ptr((u64)ciov.iov_base);
 107                 dst->iov_len = ciov.iov_len;
 108                 return 0;
 109         }
 110 #endif
 111         src = (struct iovec __user *) arg;
 112         if (copy_from_user(dst, &src[index], sizeof(*dst)))
 113                 return -EFAULT;
 114         return 0;
 115 }
 116
 117 static int io_buffer_validate(struct iovec *iov)
 118 {
 119         unsigned long tmp, acct_len = iov->iov_len + (PAGE_SIZE - 1);
 120
 121         /*
 122          * Don't impose further limits on the size and buffer
 123          * constraints here, we'll -EINVAL later when IO is
 124          * submitted if they are wrong.
 125          */
 126         if (!iov->iov_base)
 127                 return iov->iov_len ? -EFAULT : 0;
 128         if (!iov->iov_len)
 129                 return -EFAULT;
 130
 131         /* arbitrary limit, but we need something */
 132         if (iov->iov_len > SZ_1G)
 133                 return -EFAULT;
 134
 135         if (check_add_overflow((unsigned long)iov->iov_base, acct_len, &tmp))
 136                 return -EOVERFLOW;
 137
 138         return 0;
 139 }
 140
 141 static void io_buffer_unmap(struct io_ring_ctx *ctx, struct io_mapped_ubuf **slot)
 142 {
 143         struct io_mapped_ubuf *imu = *slot;
 144         unsigned int i;
 145
 146         if (imu != ctx->dummy_ubuf) {
 147                 for (i = 0; i < imu->nr_bvecs; i++)
 148                         unpin_user_page(imu->bvec[i].bv_page);
 149                 if (imu->acct_pages)
 150                         io_unaccount_mem(ctx, imu->acct_pages);
 151                 kvfree(imu);
 152         }
 153         *slot = NULL;
 154 }
 155
 156 void io_rsrc_refs_refill(struct io_ring_ctx *ctx)
 157         __must_hold(&ctx->uring_lock)
 158 {
 159         ctx->rsrc_cached_refs += IO_RSRC_REF_BATCH;
 160         percpu_ref_get_many(&ctx->rsrc_node->refs, IO_RSRC_REF_BATCH);
 161 }
 162
 163 static void __io_rsrc_put_work(struct io_rsrc_node *ref_node)
 164 {
 165         struct io_rsrc_data *rsrc_data = ref_node->rsrc_data;
 166         struct io_ring_ctx *ctx = rsrc_data->ctx;
 167         struct io_rsrc_put *prsrc, *tmp;
 168
 169         list_for_each_entry_safe(prsrc, tmp, &ref_node->rsrc_list, list) {
 170                 list_del(&prsrc->list);
 171
 172                 if (prsrc->tag) {
 173                         if (ctx->flags & IORING_SETUP_IOPOLL) {
 174                                 mutex_lock(&ctx->uring_lock);
 175                                 io_post_aux_cqe(ctx, prsrc->tag, 0, 0, true);
 176                                 mutex_unlock(&ctx->uring_lock);
 177                         } else {
 178                                 io_post_aux_cqe(ctx, prsrc->tag, 0, 0, true);
 179                         }
 180                 }
 181
 182                 rsrc_data->do_put(ctx, prsrc);
 183                 kfree(prsrc);
 184         }
 185
 186         io_rsrc_node_destroy(ref_node);
 187         if (atomic_dec_and_test(&rsrc_data->refs))
 188                 complete(&rsrc_data->done);
 189 }
 190
 191 void io_rsrc_put_work(struct work_struct *work)
 192 {
 193         struct io_ring_ctx *ctx;
 194         struct llist_node *node;
 195
 196         ctx = container_of(work, struct io_ring_ctx, rsrc_put_work.work);
 197         node = llist_del_all(&ctx->rsrc_put_llist);
 198
 199         while (node) {
 200                 struct io_rsrc_node *ref_node;
 201                 struct llist_node *next = node->next;
 202
 203                 ref_node = llist_entry(node, struct io_rsrc_node, llist);
 204                 __io_rsrc_put_work(ref_node);
 205                 node = next;
 206         }
 207 }
 208
 209 void io_wait_rsrc_data(struct io_rsrc_data *data)
 210 {
 211         if (data && !atomic_dec_and_test(&data->refs))
 212                 wait_for_completion(&data->done);
 213 }
 214
 215 void io_rsrc_node_destroy(struct io_rsrc_node *ref_node)
 216 {
 217         percpu_ref_exit(&ref_node->refs);
 218         kfree(ref_node);
 219 }
 220
 221 static __cold void io_rsrc_node_ref_zero(struct percpu_ref *ref)
 222 {
 223         struct io_rsrc_node *node = container_of(ref, struct io_rsrc_node, refs);
 224         struct io_ring_ctx *ctx = node->rsrc_data->ctx;
 225         unsigned long flags;
 226         bool first_add = false;
 227         unsigned long delay = HZ;
 228
 229         spin_lock_irqsave(&ctx->rsrc_ref_lock, flags);
 230         node->done = true;
 231
 232         /* if we are mid-quiesce then do not delay */
 233         if (node->rsrc_data->quiesce)
 234                 delay = 0;
 235
 236         while (!list_empty(&ctx->rsrc_ref_list)) {
 237                 node = list_first_entry(&ctx->rsrc_ref_list,
 238                                             struct io_rsrc_node, node);
 239                 /* recycle ref nodes in order */
 240                 if (!node->done)
 241                         break;
 242                 list_del(&node->node);
 243                 first_add |= llist_add(&node->llist, &ctx->rsrc_put_llist);
 244         }
 245         spin_unlock_irqrestore(&ctx->rsrc_ref_lock, flags);
 246
 247         if (first_add)
 248                 mod_delayed_work(system_wq, &ctx->rsrc_put_work, delay);
 249 }
 250
 251 static struct io_rsrc_node *io_rsrc_node_alloc(void)
 252 {
 253         struct io_rsrc_node *ref_node;
 254
 255         ref_node = kzalloc(sizeof(*ref_node), GFP_KERNEL);
 256         if (!ref_node)
 257                 return NULL;
 258
 259         if (percpu_ref_init(&ref_node->refs, io_rsrc_node_ref_zero,
 260                             0, GFP_KERNEL)) {
 261                 kfree(ref_node);
 262                 return NULL;
 263         }
 264         INIT_LIST_HEAD(&ref_node->node);
 265         INIT_LIST_HEAD(&ref_node->rsrc_list);
 266         ref_node->done = false;
 267         return ref_node;
 268 }
 269
 270 void io_rsrc_node_switch(struct io_ring_ctx *ctx,
 271                          struct io_rsrc_data *data_to_kill)
 272         __must_hold(&ctx->uring_lock)
 273 {
 274         WARN_ON_ONCE(!ctx->rsrc_backup_node);
 275         WARN_ON_ONCE(data_to_kill && !ctx->rsrc_node);
 276
 277         io_rsrc_refs_drop(ctx);
 278
 279         if (data_to_kill) {
 280                 struct io_rsrc_node *rsrc_node = ctx->rsrc_node;
 281
 282                 rsrc_node->rsrc_data = data_to_kill;
 283                 spin_lock_irq(&ctx->rsrc_ref_lock);
 284                 list_add_tail(&rsrc_node->node, &ctx->rsrc_ref_list);
 285                 spin_unlock_irq(&ctx->rsrc_ref_lock);
 286
 287                 atomic_inc(&data_to_kill->refs);
 288                 percpu_ref_kill(&rsrc_node->refs);
 289                 ctx->rsrc_node = NULL;
 290         }
 291
 292         if (!ctx->rsrc_node) {
 293                 ctx->rsrc_node = ctx->rsrc_backup_node;
 294                 ctx->rsrc_backup_node = NULL;
 295         }
 296 }
 297
 298 int io_rsrc_node_switch_start(struct io_ring_ctx *ctx)
 299 {
 300         if (ctx->rsrc_backup_node)
 301                 return 0;
 302         ctx->rsrc_backup_node = io_rsrc_node_alloc();
 303         return ctx->rsrc_backup_node ? 0 : -ENOMEM;
 304 }
 305
 306 __cold static int io_rsrc_ref_quiesce(struct io_rsrc_data *data,
 307                                       struct io_ring_ctx *ctx)
 308 {
 309         int ret;
 310
 311         /* As we may drop ->uring_lock, other task may have started quiesce */
 312         if (data->quiesce)
 313                 return -ENXIO;
 314
 315         data->quiesce = true;
 316         do {
 317                 ret = io_rsrc_node_switch_start(ctx);
 318                 if (ret)
 319                         break;
 320                 io_rsrc_node_switch(ctx, data);
 321
 322                 /* kill initial ref, already quiesced if zero */
 323                 if (atomic_dec_and_test(&data->refs))
 324                         break;
 325                 mutex_unlock(&ctx->uring_lock);
 326                 flush_delayed_work(&ctx->rsrc_put_work);
 327                 ret = wait_for_completion_interruptible(&data->done);
 328                 if (!ret) {
 329                         mutex_lock(&ctx->uring_lock);
 330                         if (atomic_read(&data->refs) > 0) {
 331                                 /*
 332                                  * it has been revived by another thread while
 333                                  * we were unlocked
 334                                  */
 335                                 mutex_unlock(&ctx->uring_lock);
 336                         } else {
 337                                 break;
 338                         }
 339                 }
 340
 341                 atomic_inc(&data->refs);
 342                 /* wait for all works potentially completing data->done */
 343                 flush_delayed_work(&ctx->rsrc_put_work);
 344                 reinit_completion(&data->done);
 345
 346                 ret = io_run_task_work_sig();
 347                 mutex_lock(&ctx->uring_lock);
 348         } while (ret >= 0);
 349         data->quiesce = false;
 350
 351         return ret;
 352 }
 353
 354 static void io_free_page_table(void **table, size_t size)
 355 {
 356         unsigned i, nr_tables = DIV_ROUND_UP(size, PAGE_SIZE);
 357
 358         for (i = 0; i < nr_tables; i++)
 359                 kfree(table[i]);
 360         kfree(table);
 361 }
 362
 363 static void io_rsrc_data_free(struct io_rsrc_data *data)
 364 {
 365         size_t size = data->nr * sizeof(data->tags[0][0]);
 366
 367         if (data->tags)
 368                 io_free_page_table((void **)data->tags, size);
 369         kfree(data);
 370 }
 371
 372 static __cold void **io_alloc_page_table(size_t size)
 373 {
 374         unsigned i, nr_tables = DIV_ROUND_UP(size, PAGE_SIZE);
 375         size_t init_size = size;
 376         void **table;
 377
 378         table = kcalloc(nr_tables, sizeof(*table), GFP_KERNEL_ACCOUNT);
 379         if (!table)
 380                 return NULL;
 381
 382         for (i = 0; i < nr_tables; i++) {
 383                 unsigned int this_size = min_t(size_t, size, PAGE_SIZE);
 384
 385                 table[i] = kzalloc(this_size, GFP_KERNEL_ACCOUNT);
 386                 if (!table[i]) {
 387                         io_free_page_table(table, init_size);
 388                         return NULL;
 389                 }
 390                 size -= this_size;
 391         }
 392         return table;
 393 }
 394
 395 __cold static int io_rsrc_data_alloc(struct io_ring_ctx *ctx,
 396                                      rsrc_put_fn *do_put, u64 __user *utags,
 397                                      unsigned nr, struct io_rsrc_data **pdata)
 398 {
 399         struct io_rsrc_data *data;
 400         int ret = -ENOMEM;
 401         unsigned i;
 402
 403         data = kzalloc(sizeof(*data), GFP_KERNEL);
 404         if (!data)
 405                 return -ENOMEM;
 406         data->tags = (u64 **)io_alloc_page_table(nr * sizeof(data->tags[0][0]));
 407         if (!data->tags) {
 408                 kfree(data);
 409                 return -ENOMEM;
 410         }
 411
 412         data->nr = nr;
 413         data->ctx = ctx;
 414         data->do_put = do_put;
 415         if (utags) {
 416                 ret = -EFAULT;
 417                 for (i = 0; i < nr; i++) {
 418                         u64 *tag_slot = io_get_tag_slot(data, i);
 419
 420                         if (copy_from_user(tag_slot, &utags[i],
 421                                            sizeof(*tag_slot)))
 422                                 goto fail;
 423                 }
 424         }
 425
 426         atomic_set(&data->refs, 1);
 427         init_completion(&data->done);
 428         *pdata = data;
 429         return 0;
 430 fail:
 431         io_rsrc_data_free(data);
 432         return ret;
 433 }
 434
 435 static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 436                                  struct io_uring_rsrc_update2 *up,
 437                                  unsigned nr_args)
 438 {
 439         u64 __user *tags = u64_to_user_ptr(up->tags);
 440         __s32 __user *fds = u64_to_user_ptr(up->data);
 441         struct io_rsrc_data *data = ctx->file_data;
 442         struct io_fixed_file *file_slot;
 443         struct file *file;
 444         int fd, i, err = 0;
 445         unsigned int done;
 446         bool needs_switch = false;
 447
 448         if (!ctx->file_data)
 449                 return -ENXIO;
 450         if (up->offset + nr_args > ctx->nr_user_files)
 451                 return -EINVAL;
 452
 453         for (done = 0; done < nr_args; done++) {
 454                 u64 tag = 0;
 455
 456                 if ((tags && copy_from_user(&tag, &tags[done], sizeof(tag))) ||
 457                     copy_from_user(&fd, &fds[done], sizeof(fd))) {
 458                         err = -EFAULT;
 459                         break;
 460                 }
 461                 if ((fd == IORING_REGISTER_FILES_SKIP || fd == -1) && tag) {
 462                         err = -EINVAL;
 463                         break;
 464                 }
 465                 if (fd == IORING_REGISTER_FILES_SKIP)
 466                         continue;
 467
 468                 i = array_index_nospec(up->offset + done, ctx->nr_user_files);
 469                 file_slot = io_fixed_file_slot(&ctx->file_table, i);
 470
 471                 if (file_slot->file_ptr) {
 472                         file = (struct file *)(file_slot->file_ptr & FFS_MASK);
 473                         err = io_queue_rsrc_removal(data, i, ctx->rsrc_node, file);
 474                         if (err)
 475                                 break;
 476                         file_slot->file_ptr = 0;
 477                         io_file_bitmap_clear(&ctx->file_table, i);
 478                         needs_switch = true;
 479                 }
 480                 if (fd != -1) {
 481                         file = fget(fd);
 482                         if (!file) {
 483                                 err = -EBADF;
 484                                 break;
 485                         }
 486                         /*
 487                          * Don't allow io_uring instances to be registered. If
 488                          * UNIX isn't enabled, then this causes a reference
 489                          * cycle and this instance can never get freed. If UNIX
 490                          * is enabled we'll handle it just fine, but there's
 491                          * still no point in allowing a ring fd as it doesn't
 492                          * support regular read/write anyway.
 493                          */
 494                         if (io_is_uring_fops(file)) {
 495                                 fput(file);
 496                                 err = -EBADF;
 497                                 break;
 498                         }
 499                         err = io_scm_file_account(ctx, file);
 500                         if (err) {
 501                                 fput(file);
 502                                 break;
 503                         }
 504                         *io_get_tag_slot(data, i) = tag;
 505                         io_fixed_file_set(file_slot, file);
 506                         io_file_bitmap_set(&ctx->file_table, i);
 507                 }
 508         }
 509
 510         if (needs_switch)
 511                 io_rsrc_node_switch(ctx, data);
 512         return done ? done : err;
 513 }
 514
 515 static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
 516                                    struct io_uring_rsrc_update2 *up,
 517                                    unsigned int nr_args)
 518 {
 519         u64 __user *tags = u64_to_user_ptr(up->tags);
 520         struct iovec iov, __user *iovs = u64_to_user_ptr(up->data);
 521         struct page *last_hpage = NULL;
 522         bool needs_switch = false;
 523         __u32 done;
 524         int i, err;
 525
 526         if (!ctx->buf_data)
 527                 return -ENXIO;
 528         if (up->offset + nr_args > ctx->nr_user_bufs)
 529                 return -EINVAL;
 530
 531         for (done = 0; done < nr_args; done++) {
 532                 struct io_mapped_ubuf *imu;
 533                 int offset = up->offset + done;
 534                 u64 tag = 0;
 535
 536                 err = io_copy_iov(ctx, &iov, iovs, done);
 537                 if (err)
 538                         break;
 539                 if (tags && copy_from_user(&tag, &tags[done], sizeof(tag))) {
 540                         err = -EFAULT;
 541                         break;
 542                 }
 543                 err = io_buffer_validate(&iov);
 544                 if (err)
 545                         break;
 546                 if (!iov.iov_base && tag) {
 547                         err = -EINVAL;
 548                         break;
 549                 }
 550                 err = io_sqe_buffer_register(ctx, &iov, &imu, &last_hpage);
 551                 if (err)
 552                         break;
 553
 554                 i = array_index_nospec(offset, ctx->nr_user_bufs);
 555                 if (ctx->user_bufs[i] != ctx->dummy_ubuf) {
 556                         err = io_queue_rsrc_removal(ctx->buf_data, i,
 557                                                     ctx->rsrc_node, ctx->user_bufs[i]);
 558                         if (unlikely(err)) {
 559                                 io_buffer_unmap(ctx, &imu);
 560                                 break;
 561                         }
 562                         ctx->user_bufs[i] = ctx->dummy_ubuf;
 563                         needs_switch = true;
 564                 }
 565
 566                 ctx->user_bufs[i] = imu;
 567                 *io_get_tag_slot(ctx->buf_data, offset) = tag;
 568         }
 569
 570         if (needs_switch)
 571                 io_rsrc_node_switch(ctx, ctx->buf_data);
 572         return done ? done : err;
 573 }
 574
 575 static int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type,
 576                                      struct io_uring_rsrc_update2 *up,
 577                                      unsigned nr_args)
 578 {
 579         __u32 tmp;
 580         int err;
 581
 582         if (check_add_overflow(up->offset, nr_args, &tmp))
 583                 return -EOVERFLOW;
 584         err = io_rsrc_node_switch_start(ctx);
 585         if (err)
 586                 return err;
 587
 588         switch (type) {
 589         case IORING_RSRC_FILE:
 590                 return __io_sqe_files_update(ctx, up, nr_args);
 591         case IORING_RSRC_BUFFER:
 592                 return __io_sqe_buffers_update(ctx, up, nr_args);
 593         }
 594         return -EINVAL;
 595 }
 596
 597 int io_register_files_update(struct io_ring_ctx *ctx, void __user *arg,
 598                              unsigned nr_args)
 599 {
 600         struct io_uring_rsrc_update2 up;
 601
 602         if (!nr_args)
 603                 return -EINVAL;
 604         memset(&up, 0, sizeof(up));
 605         if (copy_from_user(&up, arg, sizeof(struct io_uring_rsrc_update)))
 606                 return -EFAULT;
 607         if (up.resv || up.resv2)
 608                 return -EINVAL;
 609         return __io_register_rsrc_update(ctx, IORING_RSRC_FILE, &up, nr_args);
 610 }
 611
 612 int io_register_rsrc_update(struct io_ring_ctx *ctx, void __user *arg,
 613                             unsigned size, unsigned type)
 614 {
 615         struct io_uring_rsrc_update2 up;
 616
 617         if (size != sizeof(up))
 618                 return -EINVAL;
 619         if (copy_from_user(&up, arg, sizeof(up)))
 620                 return -EFAULT;
 621         if (!up.nr || up.resv || up.resv2)
 622                 return -EINVAL;
 623         return __io_register_rsrc_update(ctx, type, &up, up.nr);
 624 }
 625
 626 __cold int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg,
 627                             unsigned int size, unsigned int type)
 628 {
 629         struct io_uring_rsrc_register rr;
 630
 631         /* keep it extendible */
 632         if (size != sizeof(rr))
 633                 return -EINVAL;
 634
 635         memset(&rr, 0, sizeof(rr));
 636         if (copy_from_user(&rr, arg, size))
 637                 return -EFAULT;
 638         if (!rr.nr || rr.resv2)
 639                 return -EINVAL;
 640         if (rr.flags & ~IORING_RSRC_REGISTER_SPARSE)
 641                 return -EINVAL;
 642
 643         switch (type) {
 644         case IORING_RSRC_FILE:
 645                 if (rr.flags & IORING_RSRC_REGISTER_SPARSE && rr.data)
 646                         break;
 647                 return io_sqe_files_register(ctx, u64_to_user_ptr(rr.data),
 648                                              rr.nr, u64_to_user_ptr(rr.tags));
 649         case IORING_RSRC_BUFFER:
 650                 if (rr.flags & IORING_RSRC_REGISTER_SPARSE && rr.data)
 651                         break;
 652                 return io_sqe_buffers_register(ctx, u64_to_user_ptr(rr.data),
 653                                                rr.nr, u64_to_user_ptr(rr.tags));
 654         }
 655         return -EINVAL;
 656 }
 657
 658 int io_rsrc_update_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 659 {
 660         struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 661
 662         if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
 663                 return -EINVAL;
 664         if (sqe->rw_flags || sqe->splice_fd_in)
 665                 return -EINVAL;
 666
 667         up->offset = READ_ONCE(sqe->off);
 668         up->nr_args = READ_ONCE(sqe->len);
 669         if (!up->nr_args)
 670                 return -EINVAL;
 671         up->arg = READ_ONCE(sqe->addr);
 672         up->type = READ_ONCE(sqe->ioprio);
 673         return 0;
 674 }
 675
 676 static int io_files_update_with_index_alloc(struct io_kiocb *req,
 677                                             unsigned int issue_flags)
 678 {
 679         struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 680         __s32 __user *fds = u64_to_user_ptr(up->arg);
 681         unsigned int done;
 682         struct file *file;
 683         int ret, fd;
 684
 685         if (!req->ctx->file_data)
 686                 return -ENXIO;
 687
 688         for (done = 0; done < up->nr_args; done++) {
 689                 if (copy_from_user(&fd, &fds[done], sizeof(fd))) {
 690                         ret = -EFAULT;
 691                         break;
 692                 }
 693
 694                 file = fget(fd);
 695                 if (!file) {
 696                         ret = -EBADF;
 697                         break;
 698                 }
 699                 ret = io_fixed_fd_install(req, issue_flags, file,
 700                                           IORING_FILE_INDEX_ALLOC);
 701                 if (ret < 0)
 702                         break;
 703                 if (copy_to_user(&fds[done], &ret, sizeof(ret))) {
 704                         __io_close_fixed(req->ctx, issue_flags, ret);
 705                         ret = -EFAULT;
 706                         break;
 707                 }
 708         }
 709
 710         if (done)
 711                 return done;
 712         return ret;
 713 }
 714
 715 static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
 716 {
 717         struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 718         struct io_ring_ctx *ctx = req->ctx;
 719         struct io_uring_rsrc_update2 up2;
 720         int ret;
 721
 722         up2.offset = up->offset;
 723         up2.data = up->arg;
 724         up2.nr = 0;
 725         up2.tags = 0;
 726         up2.resv = 0;
 727         up2.resv2 = 0;
 728
 729         if (up->offset == IORING_FILE_INDEX_ALLOC) {
 730                 ret = io_files_update_with_index_alloc(req, issue_flags);
 731         } else {
 732                 io_ring_submit_lock(ctx, issue_flags);
 733                 ret = __io_register_rsrc_update(ctx, IORING_RSRC_FILE,
 734                                                 &up2, up->nr_args);
 735                 io_ring_submit_unlock(ctx, issue_flags);
 736         }
 737
 738         if (ret < 0)
 739                 req_set_fail(req);
 740         io_req_set_res(req, ret, 0);
 741         return IOU_OK;
 742 }
 743
 744 static int io_notif_update(struct io_kiocb *req, unsigned int issue_flags)
 745 {
 746         struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 747         struct io_ring_ctx *ctx = req->ctx;
 748         unsigned len = up->nr_args;
 749         unsigned idx_end, idx = up->offset;
 750         int ret = 0;
 751
 752         io_ring_submit_lock(ctx, issue_flags);
 753         if (unlikely(check_add_overflow(idx, len, &idx_end))) {
 754                 ret = -EOVERFLOW;
 755                 goto out;
 756         }
 757         if (unlikely(idx_end > ctx->nr_notif_slots)) {
 758                 ret = -EINVAL;
 759                 goto out;
 760         }
 761
 762         for (; idx < idx_end; idx++) {
 763                 struct io_notif_slot *slot = &ctx->notif_slots[idx];
 764
 765                 if (!slot->notif)
 766                         continue;
 767                 if (up->arg)
 768                         slot->tag = up->arg;
 769                 io_notif_slot_flush_submit(slot, issue_flags);
 770         }
 771 out:
 772         io_ring_submit_unlock(ctx, issue_flags);
 773         if (ret < 0)
 774                 req_set_fail(req);
 775         io_req_set_res(req, ret, 0);
 776         return IOU_OK;
 777 }
 778
 779 int io_rsrc_update(struct io_kiocb *req, unsigned int issue_flags)
 780 {
 781         struct io_rsrc_update *up = io_kiocb_to_cmd(req, struct io_rsrc_update);
 782
 783         switch (up->type) {
 784         case IORING_RSRC_UPDATE_FILES:
 785                 return io_files_update(req, issue_flags);
 786         case IORING_RSRC_UPDATE_NOTIF:
 787                 return io_notif_update(req, issue_flags);
 788         }
 789         return -EINVAL;
 790 }
 791
 792 int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx,
 793                           struct io_rsrc_node *node, void *rsrc)
 794 {
 795         u64 *tag_slot = io_get_tag_slot(data, idx);
 796         struct io_rsrc_put *prsrc;
 797
 798         prsrc = kzalloc(sizeof(*prsrc), GFP_KERNEL);
 799         if (!prsrc)
 800                 return -ENOMEM;
 801
 802         prsrc->tag = *tag_slot;
 803         *tag_slot = 0;
 804         prsrc->rsrc = rsrc;
 805         list_add(&prsrc->list, &node->rsrc_list);
 806         return 0;
 807 }
 808
 809 void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
 810 {
 811 #if !defined(IO_URING_SCM_ALL)
 812         int i;
 813
 814         for (i = 0; i < ctx->nr_user_files; i++) {
 815                 struct file *file = io_file_from_index(&ctx->file_table, i);
 816
 817                 if (!file)
 818                         continue;
 819                 if (io_fixed_file_slot(&ctx->file_table, i)->file_ptr & FFS_SCM)
 820                         continue;
 821                 io_file_bitmap_clear(&ctx->file_table, i);
 822                 fput(file);
 823         }
 824 #endif
 825
 826 #if defined(CONFIG_UNIX)
 827         if (ctx->ring_sock) {
 828                 struct sock *sock = ctx->ring_sock->sk;
 829                 struct sk_buff *skb;
 830
 831                 while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
 832                         kfree_skb(skb);
 833         }
 834 #endif
 835         io_free_file_tables(&ctx->file_table);
 836         io_rsrc_data_free(ctx->file_data);
 837         ctx->file_data = NULL;
 838         ctx->nr_user_files = 0;
 839 }
 840
 841 int io_sqe_files_unregister(struct io_ring_ctx *ctx)
 842 {
 843         unsigned nr = ctx->nr_user_files;
 844         int ret;
 845
 846         if (!ctx->file_data)
 847                 return -ENXIO;
 848
 849         /*
 850          * Quiesce may unlock ->uring_lock, and while it's not held
 851          * prevent new requests using the table.
 852          */
 853         ctx->nr_user_files = 0;
 854         ret = io_rsrc_ref_quiesce(ctx->file_data, ctx);
 855         ctx->nr_user_files = nr;
 856         if (!ret)
 857                 __io_sqe_files_unregister(ctx);
 858         return ret;
 859 }
 860
 861 /*
 862  * Ensure the UNIX gc is aware of our file set, so we are certain that
 863  * the io_uring can be safely unregistered on process exit, even if we have
 864  * loops in the file referencing. We account only files that can hold other
 865  * files because otherwise they can't form a loop and so are not interesting
 866  * for GC.
 867  */
 868 int __io_scm_file_account(struct io_ring_ctx *ctx, struct file *file)
 869 {
 870 #if defined(CONFIG_UNIX)
 871         struct sock *sk = ctx->ring_sock->sk;
 872         struct sk_buff_head *head = &sk->sk_receive_queue;
 873         struct scm_fp_list *fpl;
 874         struct sk_buff *skb;
 875
 876         if (likely(!io_file_need_scm(file)))
 877                 return 0;
 878
 879         /*
 880          * See if we can merge this file into an existing skb SCM_RIGHTS
 881          * file set. If there's no room, fall back to allocating a new skb
 882          * and filling it in.
 883          */
 884         spin_lock_irq(&head->lock);
 885         skb = skb_peek(head);
 886         if (skb && UNIXCB(skb).fp->count < SCM_MAX_FD)
 887                 __skb_unlink(skb, head);
 888         else
 889                 skb = NULL;
 890         spin_unlock_irq(&head->lock);
 891
 892         if (!skb) {
 893                 fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
 894                 if (!fpl)
 895                         return -ENOMEM;
 896
 897                 skb = alloc_skb(0, GFP_KERNEL);
 898                 if (!skb) {
 899                         kfree(fpl);
 900                         return -ENOMEM;
 901                 }
 902
 903                 fpl->user = get_uid(current_user());
 904                 fpl->max = SCM_MAX_FD;
 905                 fpl->count = 0;
 906
 907                 UNIXCB(skb).fp = fpl;
 908                 skb->sk = sk;
 909                 skb->destructor = unix_destruct_scm;
 910                 refcount_add(skb->truesize, &sk->sk_wmem_alloc);
 911         }
 912
 913         fpl = UNIXCB(skb).fp;
 914         fpl->fp[fpl->count++] = get_file(file);
 915         unix_inflight(fpl->user, file);
 916         skb_queue_head(head, skb);
 917         fput(file);
 918 #endif
 919         return 0;
 920 }
 921
 922 static void io_rsrc_file_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
 923 {
 924         struct file *file = prsrc->file;
 925 #if defined(CONFIG_UNIX)
 926         struct sock *sock = ctx->ring_sock->sk;
 927         struct sk_buff_head list, *head = &sock->sk_receive_queue;
 928         struct sk_buff *skb;
 929         int i;
 930
 931         if (!io_file_need_scm(file)) {
 932                 fput(file);
 933                 return;
 934         }
 935
 936         __skb_queue_head_init(&list);
 937
 938         /*
 939          * Find the skb that holds this file in its SCM_RIGHTS. When found,
 940          * remove this entry and rearrange the file array.
 941          */
 942         skb = skb_dequeue(head);
 943         while (skb) {
 944                 struct scm_fp_list *fp;
 945
 946                 fp = UNIXCB(skb).fp;
 947                 for (i = 0; i < fp->count; i++) {
 948                         int left;
 949
 950                         if (fp->fp[i] != file)
 951                                 continue;
 952
 953                         unix_notinflight(fp->user, fp->fp[i]);
 954                         left = fp->count - 1 - i;
 955                         if (left) {
 956                                 memmove(&fp->fp[i], &fp->fp[i + 1],
 957                                                 left * sizeof(struct file *));
 958                         }
 959                         fp->count--;
 960                         if (!fp->count) {
 961                                 kfree_skb(skb);
 962                                 skb = NULL;
 963                         } else {
 964                                 __skb_queue_tail(&list, skb);
 965                         }
 966                         fput(file);
 967                         file = NULL;
 968                         break;
 969                 }
 970
 971                 if (!file)
 972                         break;
 973
 974                 __skb_queue_tail(&list, skb);
 975
 976                 skb = skb_dequeue(head);
 977         }
 978
 979         if (skb_peek(&list)) {
 980                 spin_lock_irq(&head->lock);
 981                 while ((skb = __skb_dequeue(&list)) != NULL)
 982                         __skb_queue_tail(head, skb);
 983                 spin_unlock_irq(&head->lock);
 984         }
 985 #else
 986         fput(file);
 987 #endif
 988 }
 989
 990 int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 991                           unsigned nr_args, u64 __user *tags)
 992 {
 993         __s32 __user *fds = (__s32 __user *) arg;
 994         struct file *file;
 995         int fd, ret;
 996         unsigned i;
 997
 998         if (ctx->file_data)
 999                 return -EBUSY;
1000         if (!nr_args)
1001                 return -EINVAL;
1002         if (nr_args > IORING_MAX_FIXED_FILES)
1003                 return -EMFILE;
1004         if (nr_args > rlimit(RLIMIT_NOFILE))
1005                 return -EMFILE;
1006         ret = io_rsrc_node_switch_start(ctx);
1007         if (ret)
1008                 return ret;
1009         ret = io_rsrc_data_alloc(ctx, io_rsrc_file_put, tags, nr_args,
1010                                  &ctx->file_data);
1011         if (ret)
1012                 return ret;
1013
1014         if (!io_alloc_file_tables(&ctx->file_table, nr_args)) {
1015                 io_rsrc_data_free(ctx->file_data);
1016                 ctx->file_data = NULL;
1017                 return -ENOMEM;
1018         }
1019
1020         for (i = 0; i < nr_args; i++, ctx->nr_user_files++) {
1021                 struct io_fixed_file *file_slot;
1022
1023                 if (fds && copy_from_user(&fd, &fds[i], sizeof(fd))) {
1024                         ret = -EFAULT;
1025                         goto fail;
1026                 }
1027                 /* allow sparse sets */
1028                 if (!fds || fd == -1) {
1029                         ret = -EINVAL;
1030                         if (unlikely(*io_get_tag_slot(ctx->file_data, i)))
1031                                 goto fail;
1032                         continue;
1033                 }
1034
1035                 file = fget(fd);
1036                 ret = -EBADF;
1037                 if (unlikely(!file))
1038                         goto fail;
1039
1040                 /*
1041                  * Don't allow io_uring instances to be registered. If UNIX
1042                  * isn't enabled, then this causes a reference cycle and this
1043                  * instance can never get freed. If UNIX is enabled we'll
1044                  * handle it just fine, but there's still no point in allowing
1045                  * a ring fd as it doesn't support regular read/write anyway.
1046                  */
1047                 if (io_is_uring_fops(file)) {
1048                         fput(file);
1049                         goto fail;
1050                 }
1051                 ret = io_scm_file_account(ctx, file);
1052                 if (ret) {
1053                         fput(file);
1054                         goto fail;
1055                 }
1056                 file_slot = io_fixed_file_slot(&ctx->file_table, i);
1057                 io_fixed_file_set(file_slot, file);
1058                 io_file_bitmap_set(&ctx->file_table, i);
1059         }
1060
1061         /* default it to the whole table */
1062         io_file_table_set_alloc_range(ctx, 0, ctx->nr_user_files);
1063         io_rsrc_node_switch(ctx, NULL);
1064         return 0;
1065 fail:
1066         __io_sqe_files_unregister(ctx);
1067         return ret;
1068 }
1069
1070 static void io_rsrc_buf_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
1071 {
1072         io_buffer_unmap(ctx, &prsrc->buf);
1073         prsrc->buf = NULL;
1074 }
1075
1076 void __io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
1077 {
1078         unsigned int i;
1079
1080         for (i = 0; i < ctx->nr_user_bufs; i++)
1081                 io_buffer_unmap(ctx, &ctx->user_bufs[i]);
1082         kfree(ctx->user_bufs);
1083         io_rsrc_data_free(ctx->buf_data);
1084         ctx->user_bufs = NULL;
1085         ctx->buf_data = NULL;
1086         ctx->nr_user_bufs = 0;
1087 }
1088
1089 int io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
1090 {
1091         unsigned nr = ctx->nr_user_bufs;
1092         int ret;
1093
1094         if (!ctx->buf_data)
1095                 return -ENXIO;
1096
1097         /*
1098          * Quiesce may unlock ->uring_lock, and while it's not held
1099          * prevent new requests using the table.
1100          */
1101         ctx->nr_user_bufs = 0;
1102         ret = io_rsrc_ref_quiesce(ctx->buf_data, ctx);
1103         ctx->nr_user_bufs = nr;
1104         if (!ret)
1105                 __io_sqe_buffers_unregister(ctx);
1106         return ret;
1107 }
1108
1109 /*
1110  * Not super efficient, but this is just a registration time. And we do cache
1111  * the last compound head, so generally we'll only do a full search if we don't
1112  * match that one.
1113  *
1114  * We check if the given compound head page has already been accounted, to
1115  * avoid double accounting it. This allows us to account the full size of the
1116  * page, not just the constituent pages of a huge page.
1117  */
1118 static bool headpage_already_acct(struct io_ring_ctx *ctx, struct page **pages,
1119                                   int nr_pages, struct page *hpage)
1120 {
1121         int i, j;
1122
1123         /* check current page array */
1124         for (i = 0; i < nr_pages; i++) {
1125                 if (!PageCompound(pages[i]))
1126                         continue;
1127                 if (compound_head(pages[i]) == hpage)
1128                         return true;
1129         }
1130
1131         /* check previously registered pages */
1132         for (i = 0; i < ctx->nr_user_bufs; i++) {
1133                 struct io_mapped_ubuf *imu = ctx->user_bufs[i];
1134
1135                 for (j = 0; j < imu->nr_bvecs; j++) {
1136                         if (!PageCompound(imu->bvec[j].bv_page))
1137                                 continue;
1138                         if (compound_head(imu->bvec[j].bv_page) == hpage)
1139                                 return true;
1140                 }
1141         }
1142
1143         return false;
1144 }
1145
1146 static int io_buffer_account_pin(struct io_ring_ctx *ctx, struct page **pages,
1147                                  int nr_pages, struct io_mapped_ubuf *imu,
1148                                  struct page **last_hpage)
1149 {
1150         int i, ret;
1151
1152         imu->acct_pages = 0;
1153         for (i = 0; i < nr_pages; i++) {
1154                 if (!PageCompound(pages[i])) {
1155                         imu->acct_pages++;
1156                 } else {
1157                         struct page *hpage;
1158
1159                         hpage = compound_head(pages[i]);
1160                         if (hpage == *last_hpage)
1161                                 continue;
1162                         *last_hpage = hpage;
1163                         if (headpage_already_acct(ctx, pages, i, hpage))
1164                                 continue;
1165                         imu->acct_pages += page_size(hpage) >> PAGE_SHIFT;
1166                 }
1167         }
1168
1169         if (!imu->acct_pages)
1170                 return 0;
1171
1172         ret = io_account_mem(ctx, imu->acct_pages);
1173         if (ret)
1174                 imu->acct_pages = 0;
1175         return ret;
1176 }
1177
1178 struct page **io_pin_pages(unsigned long ubuf, unsigned long len, int *npages)
1179 {
1180         unsigned long start, end, nr_pages;
1181         struct vm_area_struct **vmas = NULL;
1182         struct page **pages = NULL;
1183         int i, pret, ret = -ENOMEM;
1184
1185         end = (ubuf + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1186         start = ubuf >> PAGE_SHIFT;
1187         nr_pages = end - start;
1188
1189         pages = kvmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL);
1190         if (!pages)
1191                 goto done;
1192
1193         vmas = kvmalloc_array(nr_pages, sizeof(struct vm_area_struct *),
1194                               GFP_KERNEL);
1195         if (!vmas)
1196                 goto done;
1197
1198         ret = 0;
1199         mmap_read_lock(current->mm);
1200         pret = pin_user_pages(ubuf, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
1201                               pages, vmas);
1202         if (pret == nr_pages) {
1203                 /* don't support file backed memory */
1204                 for (i = 0; i < nr_pages; i++) {
1205                         struct vm_area_struct *vma = vmas[i];
1206
1207                         if (vma_is_shmem(vma))
1208                                 continue;
1209                         if (vma->vm_file &&
1210                             !is_file_hugepages(vma->vm_file)) {
1211                                 ret = -EOPNOTSUPP;
1212                                 break;
1213                         }
1214                 }
1215                 *npages = nr_pages;
1216         } else {
1217                 ret = pret < 0 ? pret : -EFAULT;
1218         }
1219         mmap_read_unlock(current->mm);
1220         if (ret) {
1221                 /*
1222                  * if we did partial map, or found file backed vmas,
1223                  * release any pages we did get
1224                  */
1225                 if (pret > 0)
1226                         unpin_user_pages(pages, pret);
1227                 goto done;
1228         }
1229         ret = 0;
1230 done:
1231         kvfree(vmas);
1232         if (ret < 0) {
1233                 kvfree(pages);
1234                 pages = ERR_PTR(ret);
1235         }
1236         return pages;
1237 }
1238
1239 static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
1240                                   struct io_mapped_ubuf **pimu,
1241                                   struct page **last_hpage)
1242 {
1243         struct io_mapped_ubuf *imu = NULL;
1244         struct page **pages = NULL;
1245         unsigned long off;
1246         size_t size;
1247         int ret, nr_pages, i;
1248
1249         *pimu = ctx->dummy_ubuf;
1250         if (!iov->iov_base)
1251                 return 0;
1252
1253         ret = -ENOMEM;
1254         pages = io_pin_pages((unsigned long) iov->iov_base, iov->iov_len,
1255                                 &nr_pages);
1256         if (IS_ERR(pages)) {
1257                 ret = PTR_ERR(pages);
1258                 pages = NULL;
1259                 goto done;
1260         }
1261
1262         imu = kvmalloc(struct_size(imu, bvec, nr_pages), GFP_KERNEL);
1263         if (!imu)
1264                 goto done;
1265
1266         ret = io_buffer_account_pin(ctx, pages, nr_pages, imu, last_hpage);
1267         if (ret) {
1268                 unpin_user_pages(pages, nr_pages);
1269                 goto done;
1270         }
1271
1272         off = (unsigned long) iov->iov_base & ~PAGE_MASK;
1273         size = iov->iov_len;
1274         for (i = 0; i < nr_pages; i++) {
1275                 size_t vec_len;
1276
1277                 vec_len = min_t(size_t, size, PAGE_SIZE - off);
1278                 imu->bvec[i].bv_page = pages[i];
1279                 imu->bvec[i].bv_len = vec_len;
1280                 imu->bvec[i].bv_offset = off;
1281                 off = 0;
1282                 size -= vec_len;
1283         }
1284         /* store original address for later verification */
1285         imu->ubuf = (unsigned long) iov->iov_base;
1286         imu->ubuf_end = imu->ubuf + iov->iov_len;
1287         imu->nr_bvecs = nr_pages;
1288         *pimu = imu;
1289         ret = 0;
1290 done:
1291         if (ret)
1292                 kvfree(imu);
1293         kvfree(pages);
1294         return ret;
1295 }
1296
1297 static int io_buffers_map_alloc(struct io_ring_ctx *ctx, unsigned int nr_args)
1298 {
1299         ctx->user_bufs = kcalloc(nr_args, sizeof(*ctx->user_bufs), GFP_KERNEL);
1300         return ctx->user_bufs ? 0 : -ENOMEM;
1301 }
1302
1303 int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
1304                             unsigned int nr_args, u64 __user *tags)
1305 {
1306         struct page *last_hpage = NULL;
1307         struct io_rsrc_data *data;
1308         int i, ret;
1309         struct iovec iov;
1310
1311         BUILD_BUG_ON(IORING_MAX_REG_BUFFERS >= (1u << 16));
1312
1313         if (ctx->user_bufs)
1314                 return -EBUSY;
1315         if (!nr_args || nr_args > IORING_MAX_REG_BUFFERS)
1316                 return -EINVAL;
1317         ret = io_rsrc_node_switch_start(ctx);
1318         if (ret)
1319                 return ret;
1320         ret = io_rsrc_data_alloc(ctx, io_rsrc_buf_put, tags, nr_args, &data);
1321         if (ret)
1322                 return ret;
1323         ret = io_buffers_map_alloc(ctx, nr_args);
1324         if (ret) {
1325                 io_rsrc_data_free(data);
1326                 return ret;
1327         }
1328
1329         for (i = 0; i < nr_args; i++, ctx->nr_user_bufs++) {
1330                 if (arg) {
1331                         ret = io_copy_iov(ctx, &iov, arg, i);
1332                         if (ret)
1333                                 break;
1334                         ret = io_buffer_validate(&iov);
1335                         if (ret)
1336                                 break;
1337                 } else {
1338                         memset(&iov, 0, sizeof(iov));
1339                 }
1340
1341                 if (!iov.iov_base && *io_get_tag_slot(data, i)) {
1342                         ret = -EINVAL;
1343                         break;
1344                 }
1345
1346                 ret = io_sqe_buffer_register(ctx, &iov, &ctx->user_bufs[i],
1347                                              &last_hpage);
1348                 if (ret)
1349                         break;
1350         }
1351
1352         WARN_ON_ONCE(ctx->buf_data);
1353
1354         ctx->buf_data = data;
1355         if (ret)
1356                 __io_sqe_buffers_unregister(ctx);
1357         else
1358                 io_rsrc_node_switch(ctx, NULL);
1359         return ret;
1360 }
1361
1362 int io_import_fixed(int ddir, struct iov_iter *iter,
1363                            struct io_mapped_ubuf *imu,
1364                            u64 buf_addr, size_t len)
1365 {
1366         u64 buf_end;
1367         size_t offset;
1368
1369         if (WARN_ON_ONCE(!imu))
1370                 return -EFAULT;
1371         if (unlikely(check_add_overflow(buf_addr, (u64)len, &buf_end)))
1372                 return -EFAULT;
1373         /* not inside the mapped region */
1374         if (unlikely(buf_addr < imu->ubuf || buf_end > imu->ubuf_end))
1375                 return -EFAULT;
1376
1377         /*
1378          * May not be a start of buffer, set size appropriately
1379          * and advance us to the beginning.
1380          */
1381         offset = buf_addr - imu->ubuf;
1382         iov_iter_bvec(iter, ddir, imu->bvec, imu->nr_bvecs, offset + len);
1383
1384         if (offset) {
1385                 /*
1386                  * Don't use iov_iter_advance() here, as it's really slow for
1387                  * using the latter parts of a big fixed buffer - it iterates
1388                  * over each segment manually. We can cheat a bit here, because
1389                  * we know that:
1390                  *
1391                  * 1) it's a BVEC iter, we set it up
1392                  * 2) all bvecs are PAGE_SIZE in size, except potentially the
1393                  *    first and last bvec
1394                  *
1395                  * So just find our index, and adjust the iterator afterwards.
1396                  * If the offset is within the first bvec (or the whole first
1397                  * bvec, just use iov_iter_advance(). This makes it easier
1398                  * since we can just skip the first segment, which may not
1399                  * be PAGE_SIZE aligned.
1400                  */
1401                 const struct bio_vec *bvec = imu->bvec;
1402
1403                 if (offset <= bvec->bv_len) {
1404                         iov_iter_advance(iter, offset);
1405                 } else {
1406                         unsigned long seg_skip;
1407
1408                         /* skip first vec */
1409                         offset -= bvec->bv_len;
1410                         seg_skip = 1 + (offset >> PAGE_SHIFT);
1411
1412                         iter->bvec = bvec + seg_skip;
1413                         iter->nr_segs -= seg_skip;
1414                         iter->count -= bvec->bv_len + offset;
1415                         iter->iov_offset = offset & ~PAGE_MASK;
1416                 }
1417         }
1418
1419         return 0;
1420 }