io_uring/rw.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/blk-mq.h>
   7 #include <linux/mm.h>
   8 #include <linux/slab.h>
   9 #include <linux/fsnotify.h>
  10 #include <linux/poll.h>
  11 #include <linux/nospec.h>
  12 #include <linux/compat.h>
  13 #include <linux/io_uring.h>
  14
  15 #include <uapi/linux/io_uring.h>
  16
  17 #include "io_uring.h"
  18 #include "opdef.h"
  19 #include "kbuf.h"
  20 #include "rsrc.h"
  21 #include "rw.h"
  22
  23 struct io_rw {
  24         /* NOTE: kiocb has the file as the first member, so don't do it here */
  25         struct kiocb                    kiocb;
  26         u64                             addr;
  27         u32                             len;
  28         rwf_t                           flags;
  29 };
  30
  31 static inline bool io_file_supports_nowait(struct io_kiocb *req)
  32 {
  33         return req->flags & REQ_F_SUPPORT_NOWAIT;
  34 }
  35
  36 #ifdef CONFIG_COMPAT
  37 static int io_iov_compat_buffer_select_prep(struct io_rw *rw)
  38 {
  39         struct compat_iovec __user *uiov;
  40         compat_ssize_t clen;
  41
  42         uiov = u64_to_user_ptr(rw->addr);
  43         if (!access_ok(uiov, sizeof(*uiov)))
  44                 return -EFAULT;
  45         if (__get_user(clen, &uiov->iov_len))
  46                 return -EFAULT;
  47         if (clen < 0)
  48                 return -EINVAL;
  49
  50         rw->len = clen;
  51         return 0;
  52 }
  53 #endif
  54
  55 static int io_iov_buffer_select_prep(struct io_kiocb *req)
  56 {
  57         struct iovec __user *uiov;
  58         struct iovec iov;
  59         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
  60
  61         if (rw->len != 1)
  62                 return -EINVAL;
  63
  64 #ifdef CONFIG_COMPAT
  65         if (req->ctx->compat)
  66                 return io_iov_compat_buffer_select_prep(rw);
  67 #endif
  68
  69         uiov = u64_to_user_ptr(rw->addr);
  70         if (copy_from_user(&iov, uiov, sizeof(*uiov)))
  71                 return -EFAULT;
  72         rw->len = iov.iov_len;
  73         return 0;
  74 }
  75
  76 int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
  77 {
  78         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
  79         unsigned ioprio;
  80         int ret;
  81
  82         rw->kiocb.ki_pos = READ_ONCE(sqe->off);
  83         /* used for fixed read/write too - just read unconditionally */
  84         req->buf_index = READ_ONCE(sqe->buf_index);
  85
  86         if (req->opcode == IORING_OP_READ_FIXED ||
  87             req->opcode == IORING_OP_WRITE_FIXED) {
  88                 struct io_ring_ctx *ctx = req->ctx;
  89                 u16 index;
  90
  91                 if (unlikely(req->buf_index >= ctx->nr_user_bufs))
  92                         return -EFAULT;
  93                 index = array_index_nospec(req->buf_index, ctx->nr_user_bufs);
  94                 req->imu = ctx->user_bufs[index];
  95                 io_req_set_rsrc_node(req, ctx, 0);
  96         }
  97
  98         ioprio = READ_ONCE(sqe->ioprio);
  99         if (ioprio) {
 100                 ret = ioprio_check_cap(ioprio);
 101                 if (ret)
 102                         return ret;
 103
 104                 rw->kiocb.ki_ioprio = ioprio;
 105         } else {
 106                 rw->kiocb.ki_ioprio = get_current_ioprio();
 107         }
 108
 109         rw->addr = READ_ONCE(sqe->addr);
 110         rw->len = READ_ONCE(sqe->len);
 111         rw->flags = READ_ONCE(sqe->rw_flags);
 112
 113         /* Have to do this validation here, as this is in io_read() rw->len might
 114          * have chanaged due to buffer selection
 115          */
 116         if (req->opcode == IORING_OP_READV && req->flags & REQ_F_BUFFER_SELECT) {
 117                 ret = io_iov_buffer_select_prep(req);
 118                 if (ret)
 119                         return ret;
 120         }
 121
 122         return 0;
 123 }
 124
 125 void io_readv_writev_cleanup(struct io_kiocb *req)
 126 {
 127         struct io_async_rw *io = req->async_data;
 128
 129         kfree(io->free_iovec);
 130 }
 131
 132 static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
 133 {
 134         switch (ret) {
 135         case -EIOCBQUEUED:
 136                 break;
 137         case -ERESTARTSYS:
 138         case -ERESTARTNOINTR:
 139         case -ERESTARTNOHAND:
 140         case -ERESTART_RESTARTBLOCK:
 141                 /*
 142                  * We can't just restart the syscall, since previously
 143                  * submitted sqes may already be in progress. Just fail this
 144                  * IO with EINTR.
 145                  */
 146                 ret = -EINTR;
 147                 fallthrough;
 148         default:
 149                 kiocb->ki_complete(kiocb, ret);
 150         }
 151 }
 152
 153 static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
 154 {
 155         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 156
 157         if (rw->kiocb.ki_pos != -1)
 158                 return &rw->kiocb.ki_pos;
 159
 160         if (!(req->file->f_mode & FMODE_STREAM)) {
 161                 req->flags |= REQ_F_CUR_POS;
 162                 rw->kiocb.ki_pos = req->file->f_pos;
 163                 return &rw->kiocb.ki_pos;
 164         }
 165
 166         rw->kiocb.ki_pos = 0;
 167         return NULL;
 168 }
 169
 170 static void io_req_task_queue_reissue(struct io_kiocb *req)
 171 {
 172         req->io_task_work.func = io_queue_iowq;
 173         io_req_task_work_add(req);
 174 }
 175
 176 #ifdef CONFIG_BLOCK
 177 static bool io_resubmit_prep(struct io_kiocb *req)
 178 {
 179         struct io_async_rw *io = req->async_data;
 180
 181         if (!req_has_async_data(req))
 182                 return !io_req_prep_async(req);
 183         iov_iter_restore(&io->s.iter, &io->s.iter_state);
 184         return true;
 185 }
 186
 187 static bool io_rw_should_reissue(struct io_kiocb *req)
 188 {
 189         umode_t mode = file_inode(req->file)->i_mode;
 190         struct io_ring_ctx *ctx = req->ctx;
 191
 192         if (!S_ISBLK(mode) && !S_ISREG(mode))
 193                 return false;
 194         if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() &&
 195             !(ctx->flags & IORING_SETUP_IOPOLL)))
 196                 return false;
 197         /*
 198          * If ref is dying, we might be running poll reap from the exit work.
 199          * Don't attempt to reissue from that path, just let it fail with
 200          * -EAGAIN.
 201          */
 202         if (percpu_ref_is_dying(&ctx->refs))
 203                 return false;
 204         /*
 205          * Play it safe and assume not safe to re-import and reissue if we're
 206          * not in the original thread group (or in task context).
 207          */
 208         if (!same_thread_group(req->task, current) || !in_task())
 209                 return false;
 210         return true;
 211 }
 212 #else
 213 static bool io_resubmit_prep(struct io_kiocb *req)
 214 {
 215         return false;
 216 }
 217 static bool io_rw_should_reissue(struct io_kiocb *req)
 218 {
 219         return false;
 220 }
 221 #endif
 222
 223 static void kiocb_end_write(struct io_kiocb *req)
 224 {
 225         /*
 226          * Tell lockdep we inherited freeze protection from submission
 227          * thread.
 228          */
 229         if (req->flags & REQ_F_ISREG) {
 230                 struct super_block *sb = file_inode(req->file)->i_sb;
 231
 232                 __sb_writers_acquired(sb, SB_FREEZE_WRITE);
 233                 sb_end_write(sb);
 234         }
 235 }
 236
 237 /*
 238  * Trigger the notifications after having done some IO, and finish the write
 239  * accounting, if any.
 240  */
 241 static void io_req_io_end(struct io_kiocb *req)
 242 {
 243         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 244
 245         if (rw->kiocb.ki_flags & IOCB_WRITE) {
 246                 kiocb_end_write(req);
 247                 fsnotify_modify(req->file);
 248         } else {
 249                 fsnotify_access(req->file);
 250         }
 251 }
 252
 253 static bool __io_complete_rw_common(struct io_kiocb *req, long res)
 254 {
 255         if (unlikely(res != req->cqe.res)) {
 256                 if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
 257                     io_rw_should_reissue(req)) {
 258                         /*
 259                          * Reissue will start accounting again, finish the
 260                          * current cycle.
 261                          */
 262                         io_req_io_end(req);
 263                         req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO;
 264                         return true;
 265                 }
 266                 req_set_fail(req);
 267                 req->cqe.res = res;
 268         }
 269         return false;
 270 }
 271
 272 static inline int io_fixup_rw_res(struct io_kiocb *req, long res)
 273 {
 274         struct io_async_rw *io = req->async_data;
 275
 276         /* add previously done IO, if any */
 277         if (req_has_async_data(req) && io->bytes_done > 0) {
 278                 if (res < 0)
 279                         res = io->bytes_done;
 280                 else
 281                         res += io->bytes_done;
 282         }
 283         return res;
 284 }
 285
 286 static void io_req_rw_complete(struct io_kiocb *req, bool *locked)
 287 {
 288         io_req_io_end(req);
 289
 290         if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) {
 291                 unsigned issue_flags = *locked ? 0 : IO_URING_F_UNLOCKED;
 292
 293                 req->cqe.flags |= io_put_kbuf(req, issue_flags);
 294         }
 295         io_req_task_complete(req, locked);
 296 }
 297
 298 static void io_complete_rw(struct kiocb *kiocb, long res)
 299 {
 300         struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
 301         struct io_kiocb *req = cmd_to_io_kiocb(rw);
 302
 303         if (__io_complete_rw_common(req, res))
 304                 return;
 305         io_req_set_res(req, io_fixup_rw_res(req, res), 0);
 306         req->io_task_work.func = io_req_rw_complete;
 307         io_req_task_work_add(req);
 308 }
 309
 310 static void io_complete_rw_iopoll(struct kiocb *kiocb, long res)
 311 {
 312         struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
 313         struct io_kiocb *req = cmd_to_io_kiocb(rw);
 314
 315         if (kiocb->ki_flags & IOCB_WRITE)
 316                 kiocb_end_write(req);
 317         if (unlikely(res != req->cqe.res)) {
 318                 if (res == -EAGAIN && io_rw_should_reissue(req)) {
 319                         req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO;
 320                         return;
 321                 }
 322                 req->cqe.res = res;
 323         }
 324
 325         /* order with io_iopoll_complete() checking ->iopoll_completed */
 326         smp_store_release(&req->iopoll_completed, 1);
 327 }
 328
 329 static int kiocb_done(struct io_kiocb *req, ssize_t ret,
 330                        unsigned int issue_flags)
 331 {
 332         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 333         unsigned final_ret = io_fixup_rw_res(req, ret);
 334
 335         if (req->flags & REQ_F_CUR_POS)
 336                 req->file->f_pos = rw->kiocb.ki_pos;
 337         if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) {
 338                 if (!__io_complete_rw_common(req, ret)) {
 339                         /*
 340                          * Safe to call io_end from here as we're inline
 341                          * from the submission path.
 342                          */
 343                         io_req_io_end(req);
 344                         io_req_set_res(req, final_ret,
 345                                        io_put_kbuf(req, issue_flags));
 346                         return IOU_OK;
 347                 }
 348         } else {
 349                 io_rw_done(&rw->kiocb, ret);
 350         }
 351
 352         if (req->flags & REQ_F_REISSUE) {
 353                 req->flags &= ~REQ_F_REISSUE;
 354                 if (io_resubmit_prep(req))
 355                         io_req_task_queue_reissue(req);
 356                 else
 357                         io_req_task_queue_fail(req, final_ret);
 358         }
 359         return IOU_ISSUE_SKIP_COMPLETE;
 360 }
 361
 362 static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req,
 363                                        struct io_rw_state *s,
 364                                        unsigned int issue_flags)
 365 {
 366         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 367         struct iov_iter *iter = &s->iter;
 368         u8 opcode = req->opcode;
 369         struct iovec *iovec;
 370         void __user *buf;
 371         size_t sqe_len;
 372         ssize_t ret;
 373
 374         if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
 375                 ret = io_import_fixed(ddir, iter, req->imu, rw->addr, rw->len);
 376                 if (ret)
 377                         return ERR_PTR(ret);
 378                 return NULL;
 379         }
 380
 381         buf = u64_to_user_ptr(rw->addr);
 382         sqe_len = rw->len;
 383
 384         if (opcode == IORING_OP_READ || opcode == IORING_OP_WRITE ||
 385             (req->flags & REQ_F_BUFFER_SELECT)) {
 386                 if (io_do_buffer_select(req)) {
 387                         buf = io_buffer_select(req, &sqe_len, issue_flags);
 388                         if (!buf)
 389                                 return ERR_PTR(-ENOBUFS);
 390                         rw->addr = (unsigned long) buf;
 391                         rw->len = sqe_len;
 392                 }
 393
 394                 ret = import_single_range(ddir, buf, sqe_len, s->fast_iov, iter);
 395                 if (ret)
 396                         return ERR_PTR(ret);
 397                 return NULL;
 398         }
 399
 400         iovec = s->fast_iov;
 401         ret = __import_iovec(ddir, buf, sqe_len, UIO_FASTIOV, &iovec, iter,
 402                               req->ctx->compat);
 403         if (unlikely(ret < 0))
 404                 return ERR_PTR(ret);
 405         return iovec;
 406 }
 407
 408 static inline int io_import_iovec(int rw, struct io_kiocb *req,
 409                                   struct iovec **iovec, struct io_rw_state *s,
 410                                   unsigned int issue_flags)
 411 {
 412         *iovec = __io_import_iovec(rw, req, s, issue_flags);
 413         if (unlikely(IS_ERR(*iovec)))
 414                 return PTR_ERR(*iovec);
 415
 416         iov_iter_save_state(&s->iter, &s->iter_state);
 417         return 0;
 418 }
 419
 420 static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
 421 {
 422         return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos;
 423 }
 424
 425 /*
 426  * For files that don't have ->read_iter() and ->write_iter(), handle them
 427  * by looping over ->read() or ->write() manually.
 428  */
 429 static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
 430 {
 431         struct kiocb *kiocb = &rw->kiocb;
 432         struct file *file = kiocb->ki_filp;
 433         ssize_t ret = 0;
 434         loff_t *ppos;
 435
 436         /*
 437          * Don't support polled IO through this interface, and we can't
 438          * support non-blocking either. For the latter, this just causes
 439          * the kiocb to be handled from an async context.
 440          */
 441         if (kiocb->ki_flags & IOCB_HIPRI)
 442                 return -EOPNOTSUPP;
 443         if ((kiocb->ki_flags & IOCB_NOWAIT) &&
 444             !(kiocb->ki_filp->f_flags & O_NONBLOCK))
 445                 return -EAGAIN;
 446
 447         ppos = io_kiocb_ppos(kiocb);
 448
 449         while (iov_iter_count(iter)) {
 450                 struct iovec iovec;
 451                 ssize_t nr;
 452
 453                 if (!iov_iter_is_bvec(iter)) {
 454                         iovec = iov_iter_iovec(iter);
 455                 } else {
 456                         iovec.iov_base = u64_to_user_ptr(rw->addr);
 457                         iovec.iov_len = rw->len;
 458                 }
 459
 460                 if (ddir == READ) {
 461                         nr = file->f_op->read(file, iovec.iov_base,
 462                                               iovec.iov_len, ppos);
 463                 } else {
 464                         nr = file->f_op->write(file, iovec.iov_base,
 465                                                iovec.iov_len, ppos);
 466                 }
 467
 468                 if (nr < 0) {
 469                         if (!ret)
 470                                 ret = nr;
 471                         break;
 472                 }
 473                 ret += nr;
 474                 if (!iov_iter_is_bvec(iter)) {
 475                         iov_iter_advance(iter, nr);
 476                 } else {
 477                         rw->addr += nr;
 478                         rw->len -= nr;
 479                         if (!rw->len)
 480                                 break;
 481                 }
 482                 if (nr != iovec.iov_len)
 483                         break;
 484         }
 485
 486         return ret;
 487 }
 488
 489 static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
 490                           const struct iovec *fast_iov, struct iov_iter *iter)
 491 {
 492         struct io_async_rw *io = req->async_data;
 493
 494         memcpy(&io->s.iter, iter, sizeof(*iter));
 495         io->free_iovec = iovec;
 496         io->bytes_done = 0;
 497         /* can only be fixed buffers, no need to do anything */
 498         if (iov_iter_is_bvec(iter))
 499                 return;
 500         if (!iovec) {
 501                 unsigned iov_off = 0;
 502
 503                 io->s.iter.iov = io->s.fast_iov;
 504                 if (iter->iov != fast_iov) {
 505                         iov_off = iter->iov - fast_iov;
 506                         io->s.iter.iov += iov_off;
 507                 }
 508                 if (io->s.fast_iov != fast_iov)
 509                         memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off,
 510                                sizeof(struct iovec) * iter->nr_segs);
 511         } else {
 512                 req->flags |= REQ_F_NEED_CLEANUP;
 513         }
 514 }
 515
 516 static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
 517                              struct io_rw_state *s, bool force)
 518 {
 519         if (!force && !io_op_defs[req->opcode].prep_async)
 520                 return 0;
 521         if (!req_has_async_data(req)) {
 522                 struct io_async_rw *iorw;
 523
 524                 if (io_alloc_async_data(req)) {
 525                         kfree(iovec);
 526                         return -ENOMEM;
 527                 }
 528
 529                 io_req_map_rw(req, iovec, s->fast_iov, &s->iter);
 530                 iorw = req->async_data;
 531                 /* we've copied and mapped the iter, ensure state is saved */
 532                 iov_iter_save_state(&iorw->s.iter, &iorw->s.iter_state);
 533         }
 534         return 0;
 535 }
 536
 537 static inline int io_rw_prep_async(struct io_kiocb *req, int rw)
 538 {
 539         struct io_async_rw *iorw = req->async_data;
 540         struct iovec *iov;
 541         int ret;
 542
 543         /* submission path, ->uring_lock should already be taken */
 544         ret = io_import_iovec(rw, req, &iov, &iorw->s, 0);
 545         if (unlikely(ret < 0))
 546                 return ret;
 547
 548         iorw->bytes_done = 0;
 549         iorw->free_iovec = iov;
 550         if (iov)
 551                 req->flags |= REQ_F_NEED_CLEANUP;
 552         return 0;
 553 }
 554
 555 int io_readv_prep_async(struct io_kiocb *req)
 556 {
 557         return io_rw_prep_async(req, ITER_DEST);
 558 }
 559
 560 int io_writev_prep_async(struct io_kiocb *req)
 561 {
 562         return io_rw_prep_async(req, ITER_SOURCE);
 563 }
 564
 565 /*
 566  * This is our waitqueue callback handler, registered through __folio_lock_async()
 567  * when we initially tried to do the IO with the iocb armed our waitqueue.
 568  * This gets called when the page is unlocked, and we generally expect that to
 569  * happen when the page IO is completed and the page is now uptodate. This will
 570  * queue a task_work based retry of the operation, attempting to copy the data
 571  * again. If the latter fails because the page was NOT uptodate, then we will
 572  * do a thread based blocking retry of the operation. That's the unexpected
 573  * slow path.
 574  */
 575 static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode,
 576                              int sync, void *arg)
 577 {
 578         struct wait_page_queue *wpq;
 579         struct io_kiocb *req = wait->private;
 580         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 581         struct wait_page_key *key = arg;
 582
 583         wpq = container_of(wait, struct wait_page_queue, wait);
 584
 585         if (!wake_page_match(wpq, key))
 586                 return 0;
 587
 588         rw->kiocb.ki_flags &= ~IOCB_WAITQ;
 589         list_del_init(&wait->entry);
 590         io_req_task_queue(req);
 591         return 1;
 592 }
 593
 594 /*
 595  * This controls whether a given IO request should be armed for async page
 596  * based retry. If we return false here, the request is handed to the async
 597  * worker threads for retry. If we're doing buffered reads on a regular file,
 598  * we prepare a private wait_page_queue entry and retry the operation. This
 599  * will either succeed because the page is now uptodate and unlocked, or it
 600  * will register a callback when the page is unlocked at IO completion. Through
 601  * that callback, io_uring uses task_work to setup a retry of the operation.
 602  * That retry will attempt the buffered read again. The retry will generally
 603  * succeed, or in rare cases where it fails, we then fall back to using the
 604  * async worker threads for a blocking retry.
 605  */
 606 static bool io_rw_should_retry(struct io_kiocb *req)
 607 {
 608         struct io_async_rw *io = req->async_data;
 609         struct wait_page_queue *wait = &io->wpq;
 610         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 611         struct kiocb *kiocb = &rw->kiocb;
 612
 613         /* never retry for NOWAIT, we just complete with -EAGAIN */
 614         if (req->flags & REQ_F_NOWAIT)
 615                 return false;
 616
 617         /* Only for buffered IO */
 618         if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI))
 619                 return false;
 620
 621         /*
 622          * just use poll if we can, and don't attempt if the fs doesn't
 623          * support callback based unlocks
 624          */
 625         if (file_can_poll(req->file) || !(req->file->f_mode & FMODE_BUF_RASYNC))
 626                 return false;
 627
 628         wait->wait.func = io_async_buf_func;
 629         wait->wait.private = req;
 630         wait->wait.flags = 0;
 631         INIT_LIST_HEAD(&wait->wait.entry);
 632         kiocb->ki_flags |= IOCB_WAITQ;
 633         kiocb->ki_flags &= ~IOCB_NOWAIT;
 634         kiocb->ki_waitq = wait;
 635         return true;
 636 }
 637
 638 static inline int io_iter_do_read(struct io_rw *rw, struct iov_iter *iter)
 639 {
 640         struct file *file = rw->kiocb.ki_filp;
 641
 642         if (likely(file->f_op->read_iter))
 643                 return call_read_iter(file, &rw->kiocb, iter);
 644         else if (file->f_op->read)
 645                 return loop_rw_iter(READ, rw, iter);
 646         else
 647                 return -EINVAL;
 648 }
 649
 650 static bool need_complete_io(struct io_kiocb *req)
 651 {
 652         return req->flags & REQ_F_ISREG ||
 653                 S_ISBLK(file_inode(req->file)->i_mode);
 654 }
 655
 656 static int io_rw_init_file(struct io_kiocb *req, fmode_t mode)
 657 {
 658         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 659         struct kiocb *kiocb = &rw->kiocb;
 660         struct io_ring_ctx *ctx = req->ctx;
 661         struct file *file = req->file;
 662         int ret;
 663
 664         if (unlikely(!file || !(file->f_mode & mode)))
 665                 return -EBADF;
 666
 667         if (!io_req_ffs_set(req))
 668                 req->flags |= io_file_get_flags(file) << REQ_F_SUPPORT_NOWAIT_BIT;
 669
 670         kiocb->ki_flags = file->f_iocb_flags;
 671         ret = kiocb_set_rw_flags(kiocb, rw->flags);
 672         if (unlikely(ret))
 673                 return ret;
 674         kiocb->ki_flags |= IOCB_ALLOC_CACHE;
 675
 676         /*
 677          * If the file is marked O_NONBLOCK, still allow retry for it if it
 678          * supports async. Otherwise it's impossible to use O_NONBLOCK files
 679          * reliably. If not, or it IOCB_NOWAIT is set, don't retry.
 680          */
 681         if ((kiocb->ki_flags & IOCB_NOWAIT) ||
 682             ((file->f_flags & O_NONBLOCK) && !io_file_supports_nowait(req)))
 683                 req->flags |= REQ_F_NOWAIT;
 684
 685         if (ctx->flags & IORING_SETUP_IOPOLL) {
 686                 if (!(kiocb->ki_flags & IOCB_DIRECT) || !file->f_op->iopoll)
 687                         return -EOPNOTSUPP;
 688
 689                 kiocb->private = NULL;
 690                 kiocb->ki_flags |= IOCB_HIPRI;
 691                 kiocb->ki_complete = io_complete_rw_iopoll;
 692                 req->iopoll_completed = 0;
 693         } else {
 694                 if (kiocb->ki_flags & IOCB_HIPRI)
 695                         return -EINVAL;
 696                 kiocb->ki_complete = io_complete_rw;
 697         }
 698
 699         return 0;
 700 }
 701
 702 int io_read(struct io_kiocb *req, unsigned int issue_flags)
 703 {
 704         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 705         struct io_rw_state __s, *s = &__s;
 706         struct iovec *iovec;
 707         struct kiocb *kiocb = &rw->kiocb;
 708         bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
 709         struct io_async_rw *io;
 710         ssize_t ret, ret2;
 711         loff_t *ppos;
 712
 713         if (!req_has_async_data(req)) {
 714                 ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
 715                 if (unlikely(ret < 0))
 716                         return ret;
 717         } else {
 718                 io = req->async_data;
 719                 s = &io->s;
 720
 721                 /*
 722                  * Safe and required to re-import if we're using provided
 723                  * buffers, as we dropped the selected one before retry.
 724                  */
 725                 if (io_do_buffer_select(req)) {
 726                         ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
 727                         if (unlikely(ret < 0))
 728                                 return ret;
 729                 }
 730
 731                 /*
 732                  * We come here from an earlier attempt, restore our state to
 733                  * match in case it doesn't. It's cheap enough that we don't
 734                  * need to make this conditional.
 735                  */
 736                 iov_iter_restore(&s->iter, &s->iter_state);
 737                 iovec = NULL;
 738         }
 739         ret = io_rw_init_file(req, FMODE_READ);
 740         if (unlikely(ret)) {
 741                 kfree(iovec);
 742                 return ret;
 743         }
 744         req->cqe.res = iov_iter_count(&s->iter);
 745
 746         if (force_nonblock) {
 747                 /* If the file doesn't support async, just async punt */
 748                 if (unlikely(!io_file_supports_nowait(req))) {
 749                         ret = io_setup_async_rw(req, iovec, s, true);
 750                         return ret ?: -EAGAIN;
 751                 }
 752                 kiocb->ki_flags |= IOCB_NOWAIT;
 753         } else {
 754                 /* Ensure we clear previously set non-block flag */
 755                 kiocb->ki_flags &= ~IOCB_NOWAIT;
 756         }
 757
 758         ppos = io_kiocb_update_pos(req);
 759
 760         ret = rw_verify_area(READ, req->file, ppos, req->cqe.res);
 761         if (unlikely(ret)) {
 762                 kfree(iovec);
 763                 return ret;
 764         }
 765
 766         ret = io_iter_do_read(rw, &s->iter);
 767
 768         if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
 769                 req->flags &= ~REQ_F_REISSUE;
 770                 /* if we can poll, just do that */
 771                 if (req->opcode == IORING_OP_READ && file_can_poll(req->file))
 772                         return -EAGAIN;
 773                 /* IOPOLL retry should happen for io-wq threads */
 774                 if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
 775                         goto done;
 776                 /* no retry on NONBLOCK nor RWF_NOWAIT */
 777                 if (req->flags & REQ_F_NOWAIT)
 778                         goto done;
 779                 ret = 0;
 780         } else if (ret == -EIOCBQUEUED) {
 781                 if (iovec)
 782                         kfree(iovec);
 783                 return IOU_ISSUE_SKIP_COMPLETE;
 784         } else if (ret == req->cqe.res || ret <= 0 || !force_nonblock ||
 785                    (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) {
 786                 /* read all, failed, already did sync or don't want to retry */
 787                 goto done;
 788         }
 789
 790         /*
 791          * Don't depend on the iter state matching what was consumed, or being
 792          * untouched in case of error. Restore it and we'll advance it
 793          * manually if we need to.
 794          */
 795         iov_iter_restore(&s->iter, &s->iter_state);
 796
 797         ret2 = io_setup_async_rw(req, iovec, s, true);
 798         iovec = NULL;
 799         if (ret2) {
 800                 ret = ret > 0 ? ret : ret2;
 801                 goto done;
 802         }
 803
 804         io = req->async_data;
 805         s = &io->s;
 806         /*
 807          * Now use our persistent iterator and state, if we aren't already.
 808          * We've restored and mapped the iter to match.
 809          */
 810
 811         do {
 812                 /*
 813                  * We end up here because of a partial read, either from
 814                  * above or inside this loop. Advance the iter by the bytes
 815                  * that were consumed.
 816                  */
 817                 iov_iter_advance(&s->iter, ret);
 818                 if (!iov_iter_count(&s->iter))
 819                         break;
 820                 io->bytes_done += ret;
 821                 iov_iter_save_state(&s->iter, &s->iter_state);
 822
 823                 /* if we can retry, do so with the callbacks armed */
 824                 if (!io_rw_should_retry(req)) {
 825                         kiocb->ki_flags &= ~IOCB_WAITQ;
 826                         return -EAGAIN;
 827                 }
 828
 829                 req->cqe.res = iov_iter_count(&s->iter);
 830                 /*
 831                  * Now retry read with the IOCB_WAITQ parts set in the iocb. If
 832                  * we get -EIOCBQUEUED, then we'll get a notification when the
 833                  * desired page gets unlocked. We can also get a partial read
 834                  * here, and if we do, then just retry at the new offset.
 835                  */
 836                 ret = io_iter_do_read(rw, &s->iter);
 837                 if (ret == -EIOCBQUEUED)
 838                         return IOU_ISSUE_SKIP_COMPLETE;
 839                 /* we got some bytes, but not all. retry. */
 840                 kiocb->ki_flags &= ~IOCB_WAITQ;
 841                 iov_iter_restore(&s->iter, &s->iter_state);
 842         } while (ret > 0);
 843 done:
 844         /* it's faster to check here then delegate to kfree */
 845         if (iovec)
 846                 kfree(iovec);
 847         return kiocb_done(req, ret, issue_flags);
 848 }
 849
 850 int io_write(struct io_kiocb *req, unsigned int issue_flags)
 851 {
 852         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
 853         struct io_rw_state __s, *s = &__s;
 854         struct iovec *iovec;
 855         struct kiocb *kiocb = &rw->kiocb;
 856         bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
 857         ssize_t ret, ret2;
 858         loff_t *ppos;
 859
 860         if (!req_has_async_data(req)) {
 861                 ret = io_import_iovec(ITER_SOURCE, req, &iovec, s, issue_flags);
 862                 if (unlikely(ret < 0))
 863                         return ret;
 864         } else {
 865                 struct io_async_rw *io = req->async_data;
 866
 867                 s = &io->s;
 868                 iov_iter_restore(&s->iter, &s->iter_state);
 869                 iovec = NULL;
 870         }
 871         ret = io_rw_init_file(req, FMODE_WRITE);
 872         if (unlikely(ret)) {
 873                 kfree(iovec);
 874                 return ret;
 875         }
 876         req->cqe.res = iov_iter_count(&s->iter);
 877
 878         if (force_nonblock) {
 879                 /* If the file doesn't support async, just async punt */
 880                 if (unlikely(!io_file_supports_nowait(req)))
 881                         goto copy_iov;
 882
 883                 /* File path supports NOWAIT for non-direct_IO only for block devices. */
 884                 if (!(kiocb->ki_flags & IOCB_DIRECT) &&
 885                         !(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) &&
 886                         (req->flags & REQ_F_ISREG))
 887                         goto copy_iov;
 888
 889                 kiocb->ki_flags |= IOCB_NOWAIT;
 890         } else {
 891                 /* Ensure we clear previously set non-block flag */
 892                 kiocb->ki_flags &= ~IOCB_NOWAIT;
 893         }
 894
 895         ppos = io_kiocb_update_pos(req);
 896
 897         ret = rw_verify_area(WRITE, req->file, ppos, req->cqe.res);
 898         if (unlikely(ret)) {
 899                 kfree(iovec);
 900                 return ret;
 901         }
 902
 903         /*
 904          * Open-code file_start_write here to grab freeze protection,
 905          * which will be released by another thread in
 906          * io_complete_rw().  Fool lockdep by telling it the lock got
 907          * released so that it doesn't complain about the held lock when
 908          * we return to userspace.
 909          */
 910         if (req->flags & REQ_F_ISREG) {
 911                 sb_start_write(file_inode(req->file)->i_sb);
 912                 __sb_writers_release(file_inode(req->file)->i_sb,
 913                                         SB_FREEZE_WRITE);
 914         }
 915         kiocb->ki_flags |= IOCB_WRITE;
 916
 917         if (likely(req->file->f_op->write_iter))
 918                 ret2 = call_write_iter(req->file, kiocb, &s->iter);
 919         else if (req->file->f_op->write)
 920                 ret2 = loop_rw_iter(WRITE, rw, &s->iter);
 921         else
 922                 ret2 = -EINVAL;
 923
 924         if (req->flags & REQ_F_REISSUE) {
 925                 req->flags &= ~REQ_F_REISSUE;
 926                 ret2 = -EAGAIN;
 927         }
 928
 929         /*
 930          * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just
 931          * retry them without IOCB_NOWAIT.
 932          */
 933         if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT))
 934                 ret2 = -EAGAIN;
 935         /* no retry on NONBLOCK nor RWF_NOWAIT */
 936         if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT))
 937                 goto done;
 938         if (!force_nonblock || ret2 != -EAGAIN) {
 939                 /* IOPOLL retry should happen for io-wq threads */
 940                 if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL))
 941                         goto copy_iov;
 942
 943                 if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) {
 944                         struct io_async_rw *io;
 945
 946                         trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2,
 947                                                 req->cqe.res, ret2);
 948
 949                         /* This is a partial write. The file pos has already been
 950                          * updated, setup the async struct to complete the request
 951                          * in the worker. Also update bytes_done to account for
 952                          * the bytes already written.
 953                          */
 954                         iov_iter_save_state(&s->iter, &s->iter_state);
 955                         ret = io_setup_async_rw(req, iovec, s, true);
 956
 957                         io = req->async_data;
 958                         if (io)
 959                                 io->bytes_done += ret2;
 960
 961                         if (kiocb->ki_flags & IOCB_WRITE)
 962                                 kiocb_end_write(req);
 963                         return ret ? ret : -EAGAIN;
 964                 }
 965 done:
 966                 ret = kiocb_done(req, ret2, issue_flags);
 967         } else {
 968 copy_iov:
 969                 iov_iter_restore(&s->iter, &s->iter_state);
 970                 ret = io_setup_async_rw(req, iovec, s, false);
 971                 if (!ret) {
 972                         if (kiocb->ki_flags & IOCB_WRITE)
 973                                 kiocb_end_write(req);
 974                         return -EAGAIN;
 975                 }
 976                 return ret;
 977         }
 978         /* it's reportedly faster than delegating the null check to kfree() */
 979         if (iovec)
 980                 kfree(iovec);
 981         return ret;
 982 }
 983
 984 static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
 985 {
 986         io_commit_cqring_flush(ctx);
 987         if (ctx->flags & IORING_SETUP_SQPOLL)
 988                 io_cqring_wake(ctx);
 989 }
 990
 991 void io_rw_fail(struct io_kiocb *req)
 992 {
 993         int res;
 994
 995         res = io_fixup_rw_res(req, req->cqe.res);
 996         io_req_set_res(req, res, req->cqe.flags);
 997 }
 998
 999 int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
1000 {
1001         struct io_wq_work_node *pos, *start, *prev;
1002         unsigned int poll_flags = BLK_POLL_NOSLEEP;
1003         DEFINE_IO_COMP_BATCH(iob);
1004         int nr_events = 0;
1005
1006         /*
1007          * Only spin for completions if we don't have multiple devices hanging
1008          * off our complete list.
1009          */
1010         if (ctx->poll_multi_queue || force_nonspin)
1011                 poll_flags |= BLK_POLL_ONESHOT;
1012
1013         wq_list_for_each(pos, start, &ctx->iopoll_list) {
1014                 struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
1015                 struct file *file = req->file;
1016                 int ret;
1017
1018                 /*
1019                  * Move completed and retryable entries to our local lists.
1020                  * If we find a request that requires polling, break out
1021                  * and complete those lists first, if we have entries there.
1022                  */
1023                 if (READ_ONCE(req->iopoll_completed))
1024                         break;
1025
1026                 if (req->opcode == IORING_OP_URING_CMD) {
1027                         struct io_uring_cmd *ioucmd;
1028
1029                         ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
1030                         ret = file->f_op->uring_cmd_iopoll(ioucmd, &iob,
1031                                                                 poll_flags);
1032                 } else {
1033                         struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
1034
1035                         ret = file->f_op->iopoll(&rw->kiocb, &iob, poll_flags);
1036                 }
1037                 if (unlikely(ret < 0))
1038                         return ret;
1039                 else if (ret)
1040                         poll_flags |= BLK_POLL_ONESHOT;
1041
1042                 /* iopoll may have completed current req */
1043                 if (!rq_list_empty(iob.req_list) ||
1044                     READ_ONCE(req->iopoll_completed))
1045                         break;
1046         }
1047
1048         if (!rq_list_empty(iob.req_list))
1049                 iob.complete(&iob);
1050         else if (!pos)
1051                 return 0;
1052
1053         prev = start;
1054         wq_list_for_each_resume(pos, prev) {
1055                 struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
1056
1057                 /* order with io_complete_rw_iopoll(), e.g. ->result updates */
1058                 if (!smp_load_acquire(&req->iopoll_completed))
1059                         break;
1060                 nr_events++;
1061                 if (unlikely(req->flags & REQ_F_CQE_SKIP))
1062                         continue;
1063
1064                 req->cqe.flags = io_put_kbuf(req, 0);
1065                 if (unlikely(!__io_fill_cqe_req(ctx, req))) {
1066                         spin_lock(&ctx->completion_lock);
1067                         io_req_cqe_overflow(req);
1068                         spin_unlock(&ctx->completion_lock);
1069                 }
1070         }
1071
1072         if (unlikely(!nr_events))
1073                 return 0;
1074
1075         io_commit_cqring(ctx);
1076         io_cqring_ev_posted_iopoll(ctx);
1077         pos = start ? start->next : ctx->iopoll_list.first;
1078         wq_list_cut(&ctx->iopoll_list, prev, start);
1079         io_free_batch_list(ctx, pos);
1080         return nr_events;
1081 }