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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/cmd.h>
14#include <linux/indirect_call_wrapper.h>
15
16#include <uapi/linux/io_uring.h>
17
18#include "io_uring.h"
19#include "opdef.h"
20#include "kbuf.h"
21#include "rsrc.h"
22#include "poll.h"
23#include "rw.h"
24
25struct io_rw {
26 /* NOTE: kiocb has the file as the first member, so don't do it here */
27 struct kiocb kiocb;
28 u64 addr;
29 u32 len;
30 rwf_t flags;
31};
32
33static inline bool io_file_supports_nowait(struct io_kiocb *req)
34{
35 return req->flags & REQ_F_SUPPORT_NOWAIT;
36}
37
38#ifdef CONFIG_COMPAT
39static int io_iov_compat_buffer_select_prep(struct io_rw *rw)
40{
41 struct compat_iovec __user *uiov;
42 compat_ssize_t clen;
43
44 uiov = u64_to_user_ptr(rw->addr);
45 if (!access_ok(uiov, sizeof(*uiov)))
46 return -EFAULT;
47 if (__get_user(clen, &uiov->iov_len))
48 return -EFAULT;
49 if (clen < 0)
50 return -EINVAL;
51
52 rw->len = clen;
53 return 0;
54}
55#endif
56
57static int io_iov_buffer_select_prep(struct io_kiocb *req)
58{
59 struct iovec __user *uiov;
60 struct iovec iov;
61 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
62
63 if (rw->len != 1)
64 return -EINVAL;
65
66#ifdef CONFIG_COMPAT
67 if (req->ctx->compat)
68 return io_iov_compat_buffer_select_prep(rw);
69#endif
70
71 uiov = u64_to_user_ptr(rw->addr);
72 if (copy_from_user(&iov, uiov, sizeof(*uiov)))
73 return -EFAULT;
74 rw->len = iov.iov_len;
75 return 0;
76}
77
78int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
79{
80 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
81 unsigned ioprio;
82 int ret;
83
84 rw->kiocb.ki_pos = READ_ONCE(sqe->off);
85 /* used for fixed read/write too - just read unconditionally */
86 req->buf_index = READ_ONCE(sqe->buf_index);
87
88 ioprio = READ_ONCE(sqe->ioprio);
89 if (ioprio) {
90 ret = ioprio_check_cap(ioprio);
91 if (ret)
92 return ret;
93
94 rw->kiocb.ki_ioprio = ioprio;
95 } else {
96 rw->kiocb.ki_ioprio = get_current_ioprio();
97 }
98 rw->kiocb.dio_complete = NULL;
99
100 rw->addr = READ_ONCE(sqe->addr);
101 rw->len = READ_ONCE(sqe->len);
102 rw->flags = READ_ONCE(sqe->rw_flags);
103 return 0;
104}
105
106int io_prep_rwv(struct io_kiocb *req, const struct io_uring_sqe *sqe)
107{
108 int ret;
109
110 ret = io_prep_rw(req, sqe);
111 if (unlikely(ret))
112 return ret;
113
114 /*
115 * Have to do this validation here, as this is in io_read() rw->len
116 * might have chanaged due to buffer selection
117 */
118 if (req->flags & REQ_F_BUFFER_SELECT)
119 return io_iov_buffer_select_prep(req);
120
121 return 0;
122}
123
124int io_prep_rw_fixed(struct io_kiocb *req, const struct io_uring_sqe *sqe)
125{
126 struct io_ring_ctx *ctx = req->ctx;
127 u16 index;
128 int ret;
129
130 ret = io_prep_rw(req, sqe);
131 if (unlikely(ret))
132 return ret;
133
134 if (unlikely(req->buf_index >= ctx->nr_user_bufs))
135 return -EFAULT;
136 index = array_index_nospec(req->buf_index, ctx->nr_user_bufs);
137 req->imu = ctx->user_bufs[index];
138 io_req_set_rsrc_node(req, ctx, 0);
139 return 0;
140}
141
142/*
143 * Multishot read is prepared just like a normal read/write request, only
144 * difference is that we set the MULTISHOT flag.
145 */
146int io_read_mshot_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
147{
148 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
149 int ret;
150
151 /* must be used with provided buffers */
152 if (!(req->flags & REQ_F_BUFFER_SELECT))
153 return -EINVAL;
154
155 ret = io_prep_rw(req, sqe);
156 if (unlikely(ret))
157 return ret;
158
159 if (rw->addr || rw->len)
160 return -EINVAL;
161
162 req->flags |= REQ_F_APOLL_MULTISHOT;
163 return 0;
164}
165
166void io_readv_writev_cleanup(struct io_kiocb *req)
167{
168 struct io_async_rw *io = req->async_data;
169
170 kfree(io->free_iovec);
171}
172
173static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
174{
175 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
176
177 if (rw->kiocb.ki_pos != -1)
178 return &rw->kiocb.ki_pos;
179
180 if (!(req->file->f_mode & FMODE_STREAM)) {
181 req->flags |= REQ_F_CUR_POS;
182 rw->kiocb.ki_pos = req->file->f_pos;
183 return &rw->kiocb.ki_pos;
184 }
185
186 rw->kiocb.ki_pos = 0;
187 return NULL;
188}
189
190static void io_req_task_queue_reissue(struct io_kiocb *req)
191{
192 req->io_task_work.func = io_queue_iowq;
193 io_req_task_work_add(req);
194}
195
196#ifdef CONFIG_BLOCK
197static bool io_resubmit_prep(struct io_kiocb *req)
198{
199 struct io_async_rw *io = req->async_data;
200
201 if (!req_has_async_data(req))
202 return !io_req_prep_async(req);
203 iov_iter_restore(&io->s.iter, &io->s.iter_state);
204 return true;
205}
206
207static bool io_rw_should_reissue(struct io_kiocb *req)
208{
209 umode_t mode = file_inode(req->file)->i_mode;
210 struct io_ring_ctx *ctx = req->ctx;
211
212 if (!S_ISBLK(mode) && !S_ISREG(mode))
213 return false;
214 if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() &&
215 !(ctx->flags & IORING_SETUP_IOPOLL)))
216 return false;
217 /*
218 * If ref is dying, we might be running poll reap from the exit work.
219 * Don't attempt to reissue from that path, just let it fail with
220 * -EAGAIN.
221 */
222 if (percpu_ref_is_dying(&ctx->refs))
223 return false;
224 /*
225 * Play it safe and assume not safe to re-import and reissue if we're
226 * not in the original thread group (or in task context).
227 */
228 if (!same_thread_group(req->task, current) || !in_task())
229 return false;
230 return true;
231}
232#else
233static bool io_resubmit_prep(struct io_kiocb *req)
234{
235 return false;
236}
237static bool io_rw_should_reissue(struct io_kiocb *req)
238{
239 return false;
240}
241#endif
242
243static void io_req_end_write(struct io_kiocb *req)
244{
245 if (req->flags & REQ_F_ISREG) {
246 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
247
248 kiocb_end_write(&rw->kiocb);
249 }
250}
251
252/*
253 * Trigger the notifications after having done some IO, and finish the write
254 * accounting, if any.
255 */
256static void io_req_io_end(struct io_kiocb *req)
257{
258 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
259
260 if (rw->kiocb.ki_flags & IOCB_WRITE) {
261 io_req_end_write(req);
262 fsnotify_modify(req->file);
263 } else {
264 fsnotify_access(req->file);
265 }
266}
267
268static bool __io_complete_rw_common(struct io_kiocb *req, long res)
269{
270 if (unlikely(res != req->cqe.res)) {
271 if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
272 io_rw_should_reissue(req)) {
273 /*
274 * Reissue will start accounting again, finish the
275 * current cycle.
276 */
277 io_req_io_end(req);
278 req->flags |= REQ_F_REISSUE | REQ_F_BL_NO_RECYCLE;
279 return true;
280 }
281 req_set_fail(req);
282 req->cqe.res = res;
283 }
284 return false;
285}
286
287static inline int io_fixup_rw_res(struct io_kiocb *req, long res)
288{
289 struct io_async_rw *io = req->async_data;
290
291 /* add previously done IO, if any */
292 if (req_has_async_data(req) && io->bytes_done > 0) {
293 if (res < 0)
294 res = io->bytes_done;
295 else
296 res += io->bytes_done;
297 }
298 return res;
299}
300
301void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts)
302{
303 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
304 struct kiocb *kiocb = &rw->kiocb;
305
306 if ((kiocb->ki_flags & IOCB_DIO_CALLER_COMP) && kiocb->dio_complete) {
307 long res = kiocb->dio_complete(rw->kiocb.private);
308
309 io_req_set_res(req, io_fixup_rw_res(req, res), 0);
310 }
311
312 io_req_io_end(req);
313
314 if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) {
315 unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED;
316
317 req->cqe.flags |= io_put_kbuf(req, issue_flags);
318 }
319 io_req_task_complete(req, ts);
320}
321
322static void io_complete_rw(struct kiocb *kiocb, long res)
323{
324 struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
325 struct io_kiocb *req = cmd_to_io_kiocb(rw);
326
327 if (!kiocb->dio_complete || !(kiocb->ki_flags & IOCB_DIO_CALLER_COMP)) {
328 if (__io_complete_rw_common(req, res))
329 return;
330 io_req_set_res(req, io_fixup_rw_res(req, res), 0);
331 }
332 req->io_task_work.func = io_req_rw_complete;
333 __io_req_task_work_add(req, IOU_F_TWQ_LAZY_WAKE);
334}
335
336static void io_complete_rw_iopoll(struct kiocb *kiocb, long res)
337{
338 struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb);
339 struct io_kiocb *req = cmd_to_io_kiocb(rw);
340
341 if (kiocb->ki_flags & IOCB_WRITE)
342 io_req_end_write(req);
343 if (unlikely(res != req->cqe.res)) {
344 if (res == -EAGAIN && io_rw_should_reissue(req)) {
345 req->flags |= REQ_F_REISSUE | REQ_F_BL_NO_RECYCLE;
346 return;
347 }
348 req->cqe.res = res;
349 }
350
351 /* order with io_iopoll_complete() checking ->iopoll_completed */
352 smp_store_release(&req->iopoll_completed, 1);
353}
354
355static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
356{
357 /* IO was queued async, completion will happen later */
358 if (ret == -EIOCBQUEUED)
359 return;
360
361 /* transform internal restart error codes */
362 if (unlikely(ret < 0)) {
363 switch (ret) {
364 case -ERESTARTSYS:
365 case -ERESTARTNOINTR:
366 case -ERESTARTNOHAND:
367 case -ERESTART_RESTARTBLOCK:
368 /*
369 * We can't just restart the syscall, since previously
370 * submitted sqes may already be in progress. Just fail
371 * this IO with EINTR.
372 */
373 ret = -EINTR;
374 break;
375 }
376 }
377
378 INDIRECT_CALL_2(kiocb->ki_complete, io_complete_rw_iopoll,
379 io_complete_rw, kiocb, ret);
380}
381
382static int kiocb_done(struct io_kiocb *req, ssize_t ret,
383 unsigned int issue_flags)
384{
385 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
386 unsigned final_ret = io_fixup_rw_res(req, ret);
387
388 if (ret >= 0 && req->flags & REQ_F_CUR_POS)
389 req->file->f_pos = rw->kiocb.ki_pos;
390 if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) {
391 if (!__io_complete_rw_common(req, ret)) {
392 /*
393 * Safe to call io_end from here as we're inline
394 * from the submission path.
395 */
396 io_req_io_end(req);
397 io_req_set_res(req, final_ret,
398 io_put_kbuf(req, issue_flags));
399 return IOU_OK;
400 }
401 } else {
402 io_rw_done(&rw->kiocb, ret);
403 }
404
405 if (req->flags & REQ_F_REISSUE) {
406 req->flags &= ~REQ_F_REISSUE;
407 if (io_resubmit_prep(req))
408 io_req_task_queue_reissue(req);
409 else
410 io_req_task_queue_fail(req, final_ret);
411 }
412 return IOU_ISSUE_SKIP_COMPLETE;
413}
414
415static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req,
416 struct io_rw_state *s,
417 unsigned int issue_flags)
418{
419 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
420 struct iov_iter *iter = &s->iter;
421 u8 opcode = req->opcode;
422 struct iovec *iovec;
423 void __user *buf;
424 size_t sqe_len;
425 ssize_t ret;
426
427 if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
428 ret = io_import_fixed(ddir, iter, req->imu, rw->addr, rw->len);
429 if (ret)
430 return ERR_PTR(ret);
431 return NULL;
432 }
433
434 buf = u64_to_user_ptr(rw->addr);
435 sqe_len = rw->len;
436
437 if (!io_issue_defs[opcode].vectored || req->flags & REQ_F_BUFFER_SELECT) {
438 if (io_do_buffer_select(req)) {
439 buf = io_buffer_select(req, &sqe_len, issue_flags);
440 if (!buf)
441 return ERR_PTR(-ENOBUFS);
442 rw->addr = (unsigned long) buf;
443 rw->len = sqe_len;
444 }
445
446 ret = import_ubuf(ddir, buf, sqe_len, iter);
447 if (ret)
448 return ERR_PTR(ret);
449 return NULL;
450 }
451
452 iovec = s->fast_iov;
453 ret = __import_iovec(ddir, buf, sqe_len, UIO_FASTIOV, &iovec, iter,
454 req->ctx->compat);
455 if (unlikely(ret < 0))
456 return ERR_PTR(ret);
457 return iovec;
458}
459
460static inline int io_import_iovec(int rw, struct io_kiocb *req,
461 struct iovec **iovec, struct io_rw_state *s,
462 unsigned int issue_flags)
463{
464 *iovec = __io_import_iovec(rw, req, s, issue_flags);
465 if (IS_ERR(*iovec))
466 return PTR_ERR(*iovec);
467
468 iov_iter_save_state(&s->iter, &s->iter_state);
469 return 0;
470}
471
472static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
473{
474 return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos;
475}
476
477/*
478 * For files that don't have ->read_iter() and ->write_iter(), handle them
479 * by looping over ->read() or ->write() manually.
480 */
481static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter)
482{
483 struct kiocb *kiocb = &rw->kiocb;
484 struct file *file = kiocb->ki_filp;
485 ssize_t ret = 0;
486 loff_t *ppos;
487
488 /*
489 * Don't support polled IO through this interface, and we can't
490 * support non-blocking either. For the latter, this just causes
491 * the kiocb to be handled from an async context.
492 */
493 if (kiocb->ki_flags & IOCB_HIPRI)
494 return -EOPNOTSUPP;
495 if ((kiocb->ki_flags & IOCB_NOWAIT) &&
496 !(kiocb->ki_filp->f_flags & O_NONBLOCK))
497 return -EAGAIN;
498
499 ppos = io_kiocb_ppos(kiocb);
500
501 while (iov_iter_count(iter)) {
502 void __user *addr;
503 size_t len;
504 ssize_t nr;
505
506 if (iter_is_ubuf(iter)) {
507 addr = iter->ubuf + iter->iov_offset;
508 len = iov_iter_count(iter);
509 } else if (!iov_iter_is_bvec(iter)) {
510 addr = iter_iov_addr(iter);
511 len = iter_iov_len(iter);
512 } else {
513 addr = u64_to_user_ptr(rw->addr);
514 len = rw->len;
515 }
516
517 if (ddir == READ)
518 nr = file->f_op->read(file, addr, len, ppos);
519 else
520 nr = file->f_op->write(file, addr, len, ppos);
521
522 if (nr < 0) {
523 if (!ret)
524 ret = nr;
525 break;
526 }
527 ret += nr;
528 if (!iov_iter_is_bvec(iter)) {
529 iov_iter_advance(iter, nr);
530 } else {
531 rw->addr += nr;
532 rw->len -= nr;
533 if (!rw->len)
534 break;
535 }
536 if (nr != len)
537 break;
538 }
539
540 return ret;
541}
542
543static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
544 const struct iovec *fast_iov, struct iov_iter *iter)
545{
546 struct io_async_rw *io = req->async_data;
547
548 memcpy(&io->s.iter, iter, sizeof(*iter));
549 io->free_iovec = iovec;
550 io->bytes_done = 0;
551 /* can only be fixed buffers, no need to do anything */
552 if (iov_iter_is_bvec(iter) || iter_is_ubuf(iter))
553 return;
554 if (!iovec) {
555 unsigned iov_off = 0;
556
557 io->s.iter.__iov = io->s.fast_iov;
558 if (iter->__iov != fast_iov) {
559 iov_off = iter_iov(iter) - fast_iov;
560 io->s.iter.__iov += iov_off;
561 }
562 if (io->s.fast_iov != fast_iov)
563 memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off,
564 sizeof(struct iovec) * iter->nr_segs);
565 } else {
566 req->flags |= REQ_F_NEED_CLEANUP;
567 }
568}
569
570static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
571 struct io_rw_state *s, bool force)
572{
573 if (!force && !io_cold_defs[req->opcode].prep_async)
574 return 0;
575 /* opcode type doesn't need async data */
576 if (!io_cold_defs[req->opcode].async_size)
577 return 0;
578 if (!req_has_async_data(req)) {
579 struct io_async_rw *iorw;
580
581 if (io_alloc_async_data(req)) {
582 kfree(iovec);
583 return -ENOMEM;
584 }
585
586 io_req_map_rw(req, iovec, s->fast_iov, &s->iter);
587 iorw = req->async_data;
588 /* we've copied and mapped the iter, ensure state is saved */
589 iov_iter_save_state(&iorw->s.iter, &iorw->s.iter_state);
590 }
591 return 0;
592}
593
594static inline int io_rw_prep_async(struct io_kiocb *req, int rw)
595{
596 struct io_async_rw *iorw = req->async_data;
597 struct iovec *iov;
598 int ret;
599
600 iorw->bytes_done = 0;
601 iorw->free_iovec = NULL;
602
603 /* submission path, ->uring_lock should already be taken */
604 ret = io_import_iovec(rw, req, &iov, &iorw->s, 0);
605 if (unlikely(ret < 0))
606 return ret;
607
608 if (iov) {
609 iorw->free_iovec = iov;
610 req->flags |= REQ_F_NEED_CLEANUP;
611 }
612
613 return 0;
614}
615
616int io_readv_prep_async(struct io_kiocb *req)
617{
618 return io_rw_prep_async(req, ITER_DEST);
619}
620
621int io_writev_prep_async(struct io_kiocb *req)
622{
623 return io_rw_prep_async(req, ITER_SOURCE);
624}
625
626/*
627 * This is our waitqueue callback handler, registered through __folio_lock_async()
628 * when we initially tried to do the IO with the iocb armed our waitqueue.
629 * This gets called when the page is unlocked, and we generally expect that to
630 * happen when the page IO is completed and the page is now uptodate. This will
631 * queue a task_work based retry of the operation, attempting to copy the data
632 * again. If the latter fails because the page was NOT uptodate, then we will
633 * do a thread based blocking retry of the operation. That's the unexpected
634 * slow path.
635 */
636static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode,
637 int sync, void *arg)
638{
639 struct wait_page_queue *wpq;
640 struct io_kiocb *req = wait->private;
641 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
642 struct wait_page_key *key = arg;
643
644 wpq = container_of(wait, struct wait_page_queue, wait);
645
646 if (!wake_page_match(wpq, key))
647 return 0;
648
649 rw->kiocb.ki_flags &= ~IOCB_WAITQ;
650 list_del_init(&wait->entry);
651 io_req_task_queue(req);
652 return 1;
653}
654
655/*
656 * This controls whether a given IO request should be armed for async page
657 * based retry. If we return false here, the request is handed to the async
658 * worker threads for retry. If we're doing buffered reads on a regular file,
659 * we prepare a private wait_page_queue entry and retry the operation. This
660 * will either succeed because the page is now uptodate and unlocked, or it
661 * will register a callback when the page is unlocked at IO completion. Through
662 * that callback, io_uring uses task_work to setup a retry of the operation.
663 * That retry will attempt the buffered read again. The retry will generally
664 * succeed, or in rare cases where it fails, we then fall back to using the
665 * async worker threads for a blocking retry.
666 */
667static bool io_rw_should_retry(struct io_kiocb *req)
668{
669 struct io_async_rw *io = req->async_data;
670 struct wait_page_queue *wait = &io->wpq;
671 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
672 struct kiocb *kiocb = &rw->kiocb;
673
674 /* never retry for NOWAIT, we just complete with -EAGAIN */
675 if (req->flags & REQ_F_NOWAIT)
676 return false;
677
678 /* Only for buffered IO */
679 if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI))
680 return false;
681
682 /*
683 * just use poll if we can, and don't attempt if the fs doesn't
684 * support callback based unlocks
685 */
686 if (io_file_can_poll(req) || !(req->file->f_mode & FMODE_BUF_RASYNC))
687 return false;
688
689 wait->wait.func = io_async_buf_func;
690 wait->wait.private = req;
691 wait->wait.flags = 0;
692 INIT_LIST_HEAD(&wait->wait.entry);
693 kiocb->ki_flags |= IOCB_WAITQ;
694 kiocb->ki_flags &= ~IOCB_NOWAIT;
695 kiocb->ki_waitq = wait;
696 return true;
697}
698
699static inline int io_iter_do_read(struct io_rw *rw, struct iov_iter *iter)
700{
701 struct file *file = rw->kiocb.ki_filp;
702
703 if (likely(file->f_op->read_iter))
704 return call_read_iter(file, &rw->kiocb, iter);
705 else if (file->f_op->read)
706 return loop_rw_iter(READ, rw, iter);
707 else
708 return -EINVAL;
709}
710
711static bool need_complete_io(struct io_kiocb *req)
712{
713 return req->flags & REQ_F_ISREG ||
714 S_ISBLK(file_inode(req->file)->i_mode);
715}
716
717static int io_rw_init_file(struct io_kiocb *req, fmode_t mode)
718{
719 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
720 struct kiocb *kiocb = &rw->kiocb;
721 struct io_ring_ctx *ctx = req->ctx;
722 struct file *file = req->file;
723 int ret;
724
725 if (unlikely(!(file->f_mode & mode)))
726 return -EBADF;
727
728 if (!(req->flags & REQ_F_FIXED_FILE))
729 req->flags |= io_file_get_flags(file);
730
731 kiocb->ki_flags = file->f_iocb_flags;
732 ret = kiocb_set_rw_flags(kiocb, rw->flags);
733 if (unlikely(ret))
734 return ret;
735 kiocb->ki_flags |= IOCB_ALLOC_CACHE;
736
737 /*
738 * If the file is marked O_NONBLOCK, still allow retry for it if it
739 * supports async. Otherwise it's impossible to use O_NONBLOCK files
740 * reliably. If not, or it IOCB_NOWAIT is set, don't retry.
741 */
742 if ((kiocb->ki_flags & IOCB_NOWAIT) ||
743 ((file->f_flags & O_NONBLOCK) && !io_file_supports_nowait(req)))
744 req->flags |= REQ_F_NOWAIT;
745
746 if (ctx->flags & IORING_SETUP_IOPOLL) {
747 if (!(kiocb->ki_flags & IOCB_DIRECT) || !file->f_op->iopoll)
748 return -EOPNOTSUPP;
749
750 kiocb->private = NULL;
751 kiocb->ki_flags |= IOCB_HIPRI;
752 kiocb->ki_complete = io_complete_rw_iopoll;
753 req->iopoll_completed = 0;
754 } else {
755 if (kiocb->ki_flags & IOCB_HIPRI)
756 return -EINVAL;
757 kiocb->ki_complete = io_complete_rw;
758 }
759
760 return 0;
761}
762
763static int __io_read(struct io_kiocb *req, unsigned int issue_flags)
764{
765 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
766 struct io_rw_state __s, *s = &__s;
767 struct iovec *iovec;
768 struct kiocb *kiocb = &rw->kiocb;
769 bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
770 struct io_async_rw *io;
771 ssize_t ret, ret2;
772 loff_t *ppos;
773
774 if (!req_has_async_data(req)) {
775 ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
776 if (unlikely(ret < 0))
777 return ret;
778 } else {
779 io = req->async_data;
780 s = &io->s;
781
782 /*
783 * Safe and required to re-import if we're using provided
784 * buffers, as we dropped the selected one before retry.
785 */
786 if (io_do_buffer_select(req)) {
787 ret = io_import_iovec(ITER_DEST, req, &iovec, s, issue_flags);
788 if (unlikely(ret < 0))
789 return ret;
790 }
791
792 /*
793 * We come here from an earlier attempt, restore our state to
794 * match in case it doesn't. It's cheap enough that we don't
795 * need to make this conditional.
796 */
797 iov_iter_restore(&s->iter, &s->iter_state);
798 iovec = NULL;
799 }
800 ret = io_rw_init_file(req, FMODE_READ);
801 if (unlikely(ret)) {
802 kfree(iovec);
803 return ret;
804 }
805 req->cqe.res = iov_iter_count(&s->iter);
806
807 if (force_nonblock) {
808 /* If the file doesn't support async, just async punt */
809 if (unlikely(!io_file_supports_nowait(req))) {
810 ret = io_setup_async_rw(req, iovec, s, true);
811 return ret ?: -EAGAIN;
812 }
813 kiocb->ki_flags |= IOCB_NOWAIT;
814 } else {
815 /* Ensure we clear previously set non-block flag */
816 kiocb->ki_flags &= ~IOCB_NOWAIT;
817 }
818
819 ppos = io_kiocb_update_pos(req);
820
821 ret = rw_verify_area(READ, req->file, ppos, req->cqe.res);
822 if (unlikely(ret)) {
823 kfree(iovec);
824 return ret;
825 }
826
827 ret = io_iter_do_read(rw, &s->iter);
828
829 if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
830 req->flags &= ~REQ_F_REISSUE;
831 /*
832 * If we can poll, just do that. For a vectored read, we'll
833 * need to copy state first.
834 */
835 if (io_file_can_poll(req) && !io_issue_defs[req->opcode].vectored)
836 return -EAGAIN;
837 /* IOPOLL retry should happen for io-wq threads */
838 if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
839 goto done;
840 /* no retry on NONBLOCK nor RWF_NOWAIT */
841 if (req->flags & REQ_F_NOWAIT)
842 goto done;
843 ret = 0;
844 } else if (ret == -EIOCBQUEUED) {
845 if (iovec)
846 kfree(iovec);
847 return IOU_ISSUE_SKIP_COMPLETE;
848 } else if (ret == req->cqe.res || ret <= 0 || !force_nonblock ||
849 (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) {
850 /* read all, failed, already did sync or don't want to retry */
851 goto done;
852 }
853
854 /*
855 * Don't depend on the iter state matching what was consumed, or being
856 * untouched in case of error. Restore it and we'll advance it
857 * manually if we need to.
858 */
859 iov_iter_restore(&s->iter, &s->iter_state);
860
861 ret2 = io_setup_async_rw(req, iovec, s, true);
862 iovec = NULL;
863 if (ret2) {
864 ret = ret > 0 ? ret : ret2;
865 goto done;
866 }
867
868 io = req->async_data;
869 s = &io->s;
870 /*
871 * Now use our persistent iterator and state, if we aren't already.
872 * We've restored and mapped the iter to match.
873 */
874
875 do {
876 /*
877 * We end up here because of a partial read, either from
878 * above or inside this loop. Advance the iter by the bytes
879 * that were consumed.
880 */
881 iov_iter_advance(&s->iter, ret);
882 if (!iov_iter_count(&s->iter))
883 break;
884 io->bytes_done += ret;
885 iov_iter_save_state(&s->iter, &s->iter_state);
886
887 /* if we can retry, do so with the callbacks armed */
888 if (!io_rw_should_retry(req)) {
889 kiocb->ki_flags &= ~IOCB_WAITQ;
890 return -EAGAIN;
891 }
892
893 req->cqe.res = iov_iter_count(&s->iter);
894 /*
895 * Now retry read with the IOCB_WAITQ parts set in the iocb. If
896 * we get -EIOCBQUEUED, then we'll get a notification when the
897 * desired page gets unlocked. We can also get a partial read
898 * here, and if we do, then just retry at the new offset.
899 */
900 ret = io_iter_do_read(rw, &s->iter);
901 if (ret == -EIOCBQUEUED)
902 return IOU_ISSUE_SKIP_COMPLETE;
903 /* we got some bytes, but not all. retry. */
904 kiocb->ki_flags &= ~IOCB_WAITQ;
905 iov_iter_restore(&s->iter, &s->iter_state);
906 } while (ret > 0);
907done:
908 /* it's faster to check here then delegate to kfree */
909 if (iovec)
910 kfree(iovec);
911 return ret;
912}
913
914int io_read(struct io_kiocb *req, unsigned int issue_flags)
915{
916 int ret;
917
918 ret = __io_read(req, issue_flags);
919 if (ret >= 0)
920 return kiocb_done(req, ret, issue_flags);
921
922 return ret;
923}
924
925int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags)
926{
927 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
928 unsigned int cflags = 0;
929 int ret;
930
931 /*
932 * Multishot MUST be used on a pollable file
933 */
934 if (!io_file_can_poll(req))
935 return -EBADFD;
936
937 ret = __io_read(req, issue_flags);
938
939 /*
940 * If the file doesn't support proper NOWAIT, then disable multishot
941 * and stay in single shot mode.
942 */
943 if (!io_file_supports_nowait(req))
944 req->flags &= ~REQ_F_APOLL_MULTISHOT;
945
946 /*
947 * If we get -EAGAIN, recycle our buffer and just let normal poll
948 * handling arm it.
949 */
950 if (ret == -EAGAIN) {
951 /*
952 * Reset rw->len to 0 again to avoid clamping future mshot
953 * reads, in case the buffer size varies.
954 */
955 if (io_kbuf_recycle(req, issue_flags))
956 rw->len = 0;
957 if (issue_flags & IO_URING_F_MULTISHOT)
958 return IOU_ISSUE_SKIP_COMPLETE;
959 return -EAGAIN;
960 }
961
962 /*
963 * Any successful return value will keep the multishot read armed.
964 */
965 if (ret > 0 && req->flags & REQ_F_APOLL_MULTISHOT) {
966 /*
967 * Put our buffer and post a CQE. If we fail to post a CQE, then
968 * jump to the termination path. This request is then done.
969 */
970 cflags = io_put_kbuf(req, issue_flags);
971 rw->len = 0; /* similarly to above, reset len to 0 */
972
973 if (io_fill_cqe_req_aux(req,
974 issue_flags & IO_URING_F_COMPLETE_DEFER,
975 ret, cflags | IORING_CQE_F_MORE)) {
976 if (issue_flags & IO_URING_F_MULTISHOT) {
977 /*
978 * Force retry, as we might have more data to
979 * be read and otherwise it won't get retried
980 * until (if ever) another poll is triggered.
981 */
982 io_poll_multishot_retry(req);
983 return IOU_ISSUE_SKIP_COMPLETE;
984 }
985 return -EAGAIN;
986 }
987 }
988
989 /*
990 * Either an error, or we've hit overflow posting the CQE. For any
991 * multishot request, hitting overflow will terminate it.
992 */
993 io_req_set_res(req, ret, cflags);
994 if (issue_flags & IO_URING_F_MULTISHOT)
995 return IOU_STOP_MULTISHOT;
996 return IOU_OK;
997}
998
999int io_write(struct io_kiocb *req, unsigned int issue_flags)
1000{
1001 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
1002 struct io_rw_state __s, *s = &__s;
1003 struct iovec *iovec;
1004 struct kiocb *kiocb = &rw->kiocb;
1005 bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
1006 ssize_t ret, ret2;
1007 loff_t *ppos;
1008
1009 if (!req_has_async_data(req)) {
1010 ret = io_import_iovec(ITER_SOURCE, req, &iovec, s, issue_flags);
1011 if (unlikely(ret < 0))
1012 return ret;
1013 } else {
1014 struct io_async_rw *io = req->async_data;
1015
1016 s = &io->s;
1017 iov_iter_restore(&s->iter, &s->iter_state);
1018 iovec = NULL;
1019 }
1020 ret = io_rw_init_file(req, FMODE_WRITE);
1021 if (unlikely(ret)) {
1022 kfree(iovec);
1023 return ret;
1024 }
1025 req->cqe.res = iov_iter_count(&s->iter);
1026
1027 if (force_nonblock) {
1028 /* If the file doesn't support async, just async punt */
1029 if (unlikely(!io_file_supports_nowait(req)))
1030 goto copy_iov;
1031
1032 /* File path supports NOWAIT for non-direct_IO only for block devices. */
1033 if (!(kiocb->ki_flags & IOCB_DIRECT) &&
1034 !(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) &&
1035 (req->flags & REQ_F_ISREG))
1036 goto copy_iov;
1037
1038 kiocb->ki_flags |= IOCB_NOWAIT;
1039 } else {
1040 /* Ensure we clear previously set non-block flag */
1041 kiocb->ki_flags &= ~IOCB_NOWAIT;
1042 }
1043
1044 ppos = io_kiocb_update_pos(req);
1045
1046 ret = rw_verify_area(WRITE, req->file, ppos, req->cqe.res);
1047 if (unlikely(ret)) {
1048 kfree(iovec);
1049 return ret;
1050 }
1051
1052 if (req->flags & REQ_F_ISREG)
1053 kiocb_start_write(kiocb);
1054 kiocb->ki_flags |= IOCB_WRITE;
1055
1056 if (likely(req->file->f_op->write_iter))
1057 ret2 = call_write_iter(req->file, kiocb, &s->iter);
1058 else if (req->file->f_op->write)
1059 ret2 = loop_rw_iter(WRITE, rw, &s->iter);
1060 else
1061 ret2 = -EINVAL;
1062
1063 if (req->flags & REQ_F_REISSUE) {
1064 req->flags &= ~REQ_F_REISSUE;
1065 ret2 = -EAGAIN;
1066 }
1067
1068 /*
1069 * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just
1070 * retry them without IOCB_NOWAIT.
1071 */
1072 if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT))
1073 ret2 = -EAGAIN;
1074 /* no retry on NONBLOCK nor RWF_NOWAIT */
1075 if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT))
1076 goto done;
1077 if (!force_nonblock || ret2 != -EAGAIN) {
1078 /* IOPOLL retry should happen for io-wq threads */
1079 if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL))
1080 goto copy_iov;
1081
1082 if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) {
1083 struct io_async_rw *io;
1084
1085 trace_io_uring_short_write(req->ctx, kiocb->ki_pos - ret2,
1086 req->cqe.res, ret2);
1087
1088 /* This is a partial write. The file pos has already been
1089 * updated, setup the async struct to complete the request
1090 * in the worker. Also update bytes_done to account for
1091 * the bytes already written.
1092 */
1093 iov_iter_save_state(&s->iter, &s->iter_state);
1094 ret = io_setup_async_rw(req, iovec, s, true);
1095
1096 io = req->async_data;
1097 if (io)
1098 io->bytes_done += ret2;
1099
1100 if (kiocb->ki_flags & IOCB_WRITE)
1101 io_req_end_write(req);
1102 return ret ? ret : -EAGAIN;
1103 }
1104done:
1105 ret = kiocb_done(req, ret2, issue_flags);
1106 } else {
1107copy_iov:
1108 iov_iter_restore(&s->iter, &s->iter_state);
1109 ret = io_setup_async_rw(req, iovec, s, false);
1110 if (!ret) {
1111 if (kiocb->ki_flags & IOCB_WRITE)
1112 io_req_end_write(req);
1113 return -EAGAIN;
1114 }
1115 return ret;
1116 }
1117 /* it's reportedly faster than delegating the null check to kfree() */
1118 if (iovec)
1119 kfree(iovec);
1120 return ret;
1121}
1122
1123void io_rw_fail(struct io_kiocb *req)
1124{
1125 int res;
1126
1127 res = io_fixup_rw_res(req, req->cqe.res);
1128 io_req_set_res(req, res, req->cqe.flags);
1129}
1130
1131int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin)
1132{
1133 struct io_wq_work_node *pos, *start, *prev;
1134 unsigned int poll_flags = 0;
1135 DEFINE_IO_COMP_BATCH(iob);
1136 int nr_events = 0;
1137
1138 /*
1139 * Only spin for completions if we don't have multiple devices hanging
1140 * off our complete list.
1141 */
1142 if (ctx->poll_multi_queue || force_nonspin)
1143 poll_flags |= BLK_POLL_ONESHOT;
1144
1145 wq_list_for_each(pos, start, &ctx->iopoll_list) {
1146 struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
1147 struct file *file = req->file;
1148 int ret;
1149
1150 /*
1151 * Move completed and retryable entries to our local lists.
1152 * If we find a request that requires polling, break out
1153 * and complete those lists first, if we have entries there.
1154 */
1155 if (READ_ONCE(req->iopoll_completed))
1156 break;
1157
1158 if (req->opcode == IORING_OP_URING_CMD) {
1159 struct io_uring_cmd *ioucmd;
1160
1161 ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd);
1162 ret = file->f_op->uring_cmd_iopoll(ioucmd, &iob,
1163 poll_flags);
1164 } else {
1165 struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw);
1166
1167 ret = file->f_op->iopoll(&rw->kiocb, &iob, poll_flags);
1168 }
1169 if (unlikely(ret < 0))
1170 return ret;
1171 else if (ret)
1172 poll_flags |= BLK_POLL_ONESHOT;
1173
1174 /* iopoll may have completed current req */
1175 if (!rq_list_empty(iob.req_list) ||
1176 READ_ONCE(req->iopoll_completed))
1177 break;
1178 }
1179
1180 if (!rq_list_empty(iob.req_list))
1181 iob.complete(&iob);
1182 else if (!pos)
1183 return 0;
1184
1185 prev = start;
1186 wq_list_for_each_resume(pos, prev) {
1187 struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list);
1188
1189 /* order with io_complete_rw_iopoll(), e.g. ->result updates */
1190 if (!smp_load_acquire(&req->iopoll_completed))
1191 break;
1192 nr_events++;
1193 req->cqe.flags = io_put_kbuf(req, 0);
1194 }
1195 if (unlikely(!nr_events))
1196 return 0;
1197
1198 pos = start ? start->next : ctx->iopoll_list.first;
1199 wq_list_cut(&ctx->iopoll_list, prev, start);
1200
1201 if (WARN_ON_ONCE(!wq_list_empty(&ctx->submit_state.compl_reqs)))
1202 return 0;
1203 ctx->submit_state.compl_reqs.first = pos;
1204 __io_submit_flush_completions(ctx);
1205 return nr_events;
1206}