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(to: &iov, from: uiov, n: 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, issue_flags: 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 | rw->kiocb.dio_complete = NULL; |
109 | |
110 | rw->addr = READ_ONCE(sqe->addr); |
111 | rw->len = READ_ONCE(sqe->len); |
112 | rw->flags = READ_ONCE(sqe->rw_flags); |
113 | |
114 | /* Have to do this validation here, as this is in io_read() rw->len might |
115 | * have chanaged due to buffer selection |
116 | */ |
117 | if (req->opcode == IORING_OP_READV && req->flags & REQ_F_BUFFER_SELECT) { |
118 | ret = io_iov_buffer_select_prep(req); |
119 | if (ret) |
120 | return ret; |
121 | } |
122 | |
123 | return 0; |
124 | } |
125 | |
126 | /* |
127 | * Multishot read is prepared just like a normal read/write request, only |
128 | * difference is that we set the MULTISHOT flag. |
129 | */ |
130 | int io_read_mshot_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) |
131 | { |
132 | int ret; |
133 | |
134 | ret = io_prep_rw(req, sqe); |
135 | if (unlikely(ret)) |
136 | return ret; |
137 | |
138 | req->flags |= REQ_F_APOLL_MULTISHOT; |
139 | return 0; |
140 | } |
141 | |
142 | void io_readv_writev_cleanup(struct io_kiocb *req) |
143 | { |
144 | struct io_async_rw *io = req->async_data; |
145 | |
146 | kfree(objp: io->free_iovec); |
147 | } |
148 | |
149 | static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret) |
150 | { |
151 | switch (ret) { |
152 | case -EIOCBQUEUED: |
153 | break; |
154 | case -ERESTARTSYS: |
155 | case -ERESTARTNOINTR: |
156 | case -ERESTARTNOHAND: |
157 | case -ERESTART_RESTARTBLOCK: |
158 | /* |
159 | * We can't just restart the syscall, since previously |
160 | * submitted sqes may already be in progress. Just fail this |
161 | * IO with EINTR. |
162 | */ |
163 | ret = -EINTR; |
164 | fallthrough; |
165 | default: |
166 | kiocb->ki_complete(kiocb, ret); |
167 | } |
168 | } |
169 | |
170 | static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req) |
171 | { |
172 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
173 | |
174 | if (rw->kiocb.ki_pos != -1) |
175 | return &rw->kiocb.ki_pos; |
176 | |
177 | if (!(req->file->f_mode & FMODE_STREAM)) { |
178 | req->flags |= REQ_F_CUR_POS; |
179 | rw->kiocb.ki_pos = req->file->f_pos; |
180 | return &rw->kiocb.ki_pos; |
181 | } |
182 | |
183 | rw->kiocb.ki_pos = 0; |
184 | return NULL; |
185 | } |
186 | |
187 | static void io_req_task_queue_reissue(struct io_kiocb *req) |
188 | { |
189 | req->io_task_work.func = io_queue_iowq; |
190 | io_req_task_work_add(req); |
191 | } |
192 | |
193 | #ifdef CONFIG_BLOCK |
194 | static bool io_resubmit_prep(struct io_kiocb *req) |
195 | { |
196 | struct io_async_rw *io = req->async_data; |
197 | |
198 | if (!req_has_async_data(req)) |
199 | return !io_req_prep_async(req); |
200 | iov_iter_restore(i: &io->s.iter, state: &io->s.iter_state); |
201 | return true; |
202 | } |
203 | |
204 | static bool io_rw_should_reissue(struct io_kiocb *req) |
205 | { |
206 | umode_t mode = file_inode(f: req->file)->i_mode; |
207 | struct io_ring_ctx *ctx = req->ctx; |
208 | |
209 | if (!S_ISBLK(mode) && !S_ISREG(mode)) |
210 | return false; |
211 | if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() && |
212 | !(ctx->flags & IORING_SETUP_IOPOLL))) |
213 | return false; |
214 | /* |
215 | * If ref is dying, we might be running poll reap from the exit work. |
216 | * Don't attempt to reissue from that path, just let it fail with |
217 | * -EAGAIN. |
218 | */ |
219 | if (percpu_ref_is_dying(ref: &ctx->refs)) |
220 | return false; |
221 | /* |
222 | * Play it safe and assume not safe to re-import and reissue if we're |
223 | * not in the original thread group (or in task context). |
224 | */ |
225 | if (!same_thread_group(p1: req->task, current) || !in_task()) |
226 | return false; |
227 | return true; |
228 | } |
229 | #else |
230 | static bool io_resubmit_prep(struct io_kiocb *req) |
231 | { |
232 | return false; |
233 | } |
234 | static bool io_rw_should_reissue(struct io_kiocb *req) |
235 | { |
236 | return false; |
237 | } |
238 | #endif |
239 | |
240 | static void io_req_end_write(struct io_kiocb *req) |
241 | { |
242 | if (req->flags & REQ_F_ISREG) { |
243 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
244 | |
245 | kiocb_end_write(iocb: &rw->kiocb); |
246 | } |
247 | } |
248 | |
249 | /* |
250 | * Trigger the notifications after having done some IO, and finish the write |
251 | * accounting, if any. |
252 | */ |
253 | static void io_req_io_end(struct io_kiocb *req) |
254 | { |
255 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
256 | |
257 | if (rw->kiocb.ki_flags & IOCB_WRITE) { |
258 | io_req_end_write(req); |
259 | fsnotify_modify(file: req->file); |
260 | } else { |
261 | fsnotify_access(file: req->file); |
262 | } |
263 | } |
264 | |
265 | static bool __io_complete_rw_common(struct io_kiocb *req, long res) |
266 | { |
267 | if (unlikely(res != req->cqe.res)) { |
268 | if ((res == -EAGAIN || res == -EOPNOTSUPP) && |
269 | io_rw_should_reissue(req)) { |
270 | /* |
271 | * Reissue will start accounting again, finish the |
272 | * current cycle. |
273 | */ |
274 | io_req_io_end(req); |
275 | req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO; |
276 | return true; |
277 | } |
278 | req_set_fail(req); |
279 | req->cqe.res = res; |
280 | } |
281 | return false; |
282 | } |
283 | |
284 | static inline int io_fixup_rw_res(struct io_kiocb *req, long res) |
285 | { |
286 | struct io_async_rw *io = req->async_data; |
287 | |
288 | /* add previously done IO, if any */ |
289 | if (req_has_async_data(req) && io->bytes_done > 0) { |
290 | if (res < 0) |
291 | res = io->bytes_done; |
292 | else |
293 | res += io->bytes_done; |
294 | } |
295 | return res; |
296 | } |
297 | |
298 | void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts) |
299 | { |
300 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
301 | struct kiocb *kiocb = &rw->kiocb; |
302 | |
303 | if ((kiocb->ki_flags & IOCB_DIO_CALLER_COMP) && kiocb->dio_complete) { |
304 | long res = kiocb->dio_complete(rw->kiocb.private); |
305 | |
306 | io_req_set_res(req, res: io_fixup_rw_res(req, res), cflags: 0); |
307 | } |
308 | |
309 | io_req_io_end(req); |
310 | |
311 | if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) { |
312 | unsigned issue_flags = ts->locked ? 0 : IO_URING_F_UNLOCKED; |
313 | |
314 | req->cqe.flags |= io_put_kbuf(req, issue_flags); |
315 | } |
316 | io_req_task_complete(req, ts); |
317 | } |
318 | |
319 | static void io_complete_rw(struct kiocb *kiocb, long res) |
320 | { |
321 | struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); |
322 | struct io_kiocb *req = cmd_to_io_kiocb(rw); |
323 | |
324 | if (!kiocb->dio_complete || !(kiocb->ki_flags & IOCB_DIO_CALLER_COMP)) { |
325 | if (__io_complete_rw_common(req, res)) |
326 | return; |
327 | io_req_set_res(req, res: io_fixup_rw_res(req, res), cflags: 0); |
328 | } |
329 | req->io_task_work.func = io_req_rw_complete; |
330 | __io_req_task_work_add(req, flags: IOU_F_TWQ_LAZY_WAKE); |
331 | } |
332 | |
333 | static void io_complete_rw_iopoll(struct kiocb *kiocb, long res) |
334 | { |
335 | struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); |
336 | struct io_kiocb *req = cmd_to_io_kiocb(rw); |
337 | |
338 | if (kiocb->ki_flags & IOCB_WRITE) |
339 | io_req_end_write(req); |
340 | if (unlikely(res != req->cqe.res)) { |
341 | if (res == -EAGAIN && io_rw_should_reissue(req)) { |
342 | req->flags |= REQ_F_REISSUE | REQ_F_PARTIAL_IO; |
343 | return; |
344 | } |
345 | req->cqe.res = res; |
346 | } |
347 | |
348 | /* order with io_iopoll_complete() checking ->iopoll_completed */ |
349 | smp_store_release(&req->iopoll_completed, 1); |
350 | } |
351 | |
352 | static int kiocb_done(struct io_kiocb *req, ssize_t ret, |
353 | unsigned int issue_flags) |
354 | { |
355 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
356 | unsigned final_ret = io_fixup_rw_res(req, res: ret); |
357 | |
358 | if (ret >= 0 && req->flags & REQ_F_CUR_POS) |
359 | req->file->f_pos = rw->kiocb.ki_pos; |
360 | if (ret >= 0 && (rw->kiocb.ki_complete == io_complete_rw)) { |
361 | if (!__io_complete_rw_common(req, res: ret)) { |
362 | /* |
363 | * Safe to call io_end from here as we're inline |
364 | * from the submission path. |
365 | */ |
366 | io_req_io_end(req); |
367 | io_req_set_res(req, res: final_ret, |
368 | cflags: io_put_kbuf(req, issue_flags)); |
369 | return IOU_OK; |
370 | } |
371 | } else { |
372 | io_rw_done(kiocb: &rw->kiocb, ret); |
373 | } |
374 | |
375 | if (req->flags & REQ_F_REISSUE) { |
376 | req->flags &= ~REQ_F_REISSUE; |
377 | if (io_resubmit_prep(req)) |
378 | io_req_task_queue_reissue(req); |
379 | else |
380 | io_req_task_queue_fail(req, ret: final_ret); |
381 | } |
382 | return IOU_ISSUE_SKIP_COMPLETE; |
383 | } |
384 | |
385 | static struct iovec *__io_import_iovec(int ddir, struct io_kiocb *req, |
386 | struct io_rw_state *s, |
387 | unsigned int issue_flags) |
388 | { |
389 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
390 | struct iov_iter *iter = &s->iter; |
391 | u8 opcode = req->opcode; |
392 | struct iovec *iovec; |
393 | void __user *buf; |
394 | size_t sqe_len; |
395 | ssize_t ret; |
396 | |
397 | if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) { |
398 | ret = io_import_fixed(ddir, iter, imu: req->imu, buf_addr: rw->addr, len: rw->len); |
399 | if (ret) |
400 | return ERR_PTR(error: ret); |
401 | return NULL; |
402 | } |
403 | |
404 | buf = u64_to_user_ptr(rw->addr); |
405 | sqe_len = rw->len; |
406 | |
407 | if (!io_issue_defs[opcode].vectored || req->flags & REQ_F_BUFFER_SELECT) { |
408 | if (io_do_buffer_select(req)) { |
409 | buf = io_buffer_select(req, len: &sqe_len, issue_flags); |
410 | if (!buf) |
411 | return ERR_PTR(error: -ENOBUFS); |
412 | rw->addr = (unsigned long) buf; |
413 | rw->len = sqe_len; |
414 | } |
415 | |
416 | ret = import_ubuf(type: ddir, buf, len: sqe_len, i: iter); |
417 | if (ret) |
418 | return ERR_PTR(error: ret); |
419 | return NULL; |
420 | } |
421 | |
422 | iovec = s->fast_iov; |
423 | ret = __import_iovec(type: ddir, uvec: buf, nr_segs: sqe_len, UIO_FASTIOV, iovp: &iovec, i: iter, |
424 | compat: req->ctx->compat); |
425 | if (unlikely(ret < 0)) |
426 | return ERR_PTR(error: ret); |
427 | return iovec; |
428 | } |
429 | |
430 | static inline int io_import_iovec(int rw, struct io_kiocb *req, |
431 | struct iovec **iovec, struct io_rw_state *s, |
432 | unsigned int issue_flags) |
433 | { |
434 | *iovec = __io_import_iovec(ddir: rw, req, s, issue_flags); |
435 | if (IS_ERR(ptr: *iovec)) |
436 | return PTR_ERR(ptr: *iovec); |
437 | |
438 | iov_iter_save_state(iter: &s->iter, state: &s->iter_state); |
439 | return 0; |
440 | } |
441 | |
442 | static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb) |
443 | { |
444 | return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos; |
445 | } |
446 | |
447 | /* |
448 | * For files that don't have ->read_iter() and ->write_iter(), handle them |
449 | * by looping over ->read() or ->write() manually. |
450 | */ |
451 | static ssize_t loop_rw_iter(int ddir, struct io_rw *rw, struct iov_iter *iter) |
452 | { |
453 | struct kiocb *kiocb = &rw->kiocb; |
454 | struct file *file = kiocb->ki_filp; |
455 | ssize_t ret = 0; |
456 | loff_t *ppos; |
457 | |
458 | /* |
459 | * Don't support polled IO through this interface, and we can't |
460 | * support non-blocking either. For the latter, this just causes |
461 | * the kiocb to be handled from an async context. |
462 | */ |
463 | if (kiocb->ki_flags & IOCB_HIPRI) |
464 | return -EOPNOTSUPP; |
465 | if ((kiocb->ki_flags & IOCB_NOWAIT) && |
466 | !(kiocb->ki_filp->f_flags & O_NONBLOCK)) |
467 | return -EAGAIN; |
468 | |
469 | ppos = io_kiocb_ppos(kiocb); |
470 | |
471 | while (iov_iter_count(i: iter)) { |
472 | void __user *addr; |
473 | size_t len; |
474 | ssize_t nr; |
475 | |
476 | if (iter_is_ubuf(i: iter)) { |
477 | addr = iter->ubuf + iter->iov_offset; |
478 | len = iov_iter_count(i: iter); |
479 | } else if (!iov_iter_is_bvec(i: iter)) { |
480 | addr = iter_iov_addr(iter); |
481 | len = iter_iov_len(iter); |
482 | } else { |
483 | addr = u64_to_user_ptr(rw->addr); |
484 | len = rw->len; |
485 | } |
486 | |
487 | if (ddir == READ) |
488 | nr = file->f_op->read(file, addr, len, ppos); |
489 | else |
490 | nr = file->f_op->write(file, addr, len, ppos); |
491 | |
492 | if (nr < 0) { |
493 | if (!ret) |
494 | ret = nr; |
495 | break; |
496 | } |
497 | ret += nr; |
498 | if (!iov_iter_is_bvec(i: iter)) { |
499 | iov_iter_advance(i: iter, bytes: nr); |
500 | } else { |
501 | rw->addr += nr; |
502 | rw->len -= nr; |
503 | if (!rw->len) |
504 | break; |
505 | } |
506 | if (nr != len) |
507 | break; |
508 | } |
509 | |
510 | return ret; |
511 | } |
512 | |
513 | static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec, |
514 | const struct iovec *fast_iov, struct iov_iter *iter) |
515 | { |
516 | struct io_async_rw *io = req->async_data; |
517 | |
518 | memcpy(&io->s.iter, iter, sizeof(*iter)); |
519 | io->free_iovec = iovec; |
520 | io->bytes_done = 0; |
521 | /* can only be fixed buffers, no need to do anything */ |
522 | if (iov_iter_is_bvec(i: iter) || iter_is_ubuf(i: iter)) |
523 | return; |
524 | if (!iovec) { |
525 | unsigned iov_off = 0; |
526 | |
527 | io->s.iter.__iov = io->s.fast_iov; |
528 | if (iter->__iov != fast_iov) { |
529 | iov_off = iter_iov(iter) - fast_iov; |
530 | io->s.iter.__iov += iov_off; |
531 | } |
532 | if (io->s.fast_iov != fast_iov) |
533 | memcpy(io->s.fast_iov + iov_off, fast_iov + iov_off, |
534 | sizeof(struct iovec) * iter->nr_segs); |
535 | } else { |
536 | req->flags |= REQ_F_NEED_CLEANUP; |
537 | } |
538 | } |
539 | |
540 | static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec, |
541 | struct io_rw_state *s, bool force) |
542 | { |
543 | if (!force && !io_cold_defs[req->opcode].prep_async) |
544 | return 0; |
545 | if (!req_has_async_data(req)) { |
546 | struct io_async_rw *iorw; |
547 | |
548 | if (io_alloc_async_data(req)) { |
549 | kfree(objp: iovec); |
550 | return -ENOMEM; |
551 | } |
552 | |
553 | io_req_map_rw(req, iovec, fast_iov: s->fast_iov, iter: &s->iter); |
554 | iorw = req->async_data; |
555 | /* we've copied and mapped the iter, ensure state is saved */ |
556 | iov_iter_save_state(iter: &iorw->s.iter, state: &iorw->s.iter_state); |
557 | } |
558 | return 0; |
559 | } |
560 | |
561 | static inline int io_rw_prep_async(struct io_kiocb *req, int rw) |
562 | { |
563 | struct io_async_rw *iorw = req->async_data; |
564 | struct iovec *iov; |
565 | int ret; |
566 | |
567 | /* submission path, ->uring_lock should already be taken */ |
568 | ret = io_import_iovec(rw, req, iovec: &iov, s: &iorw->s, issue_flags: 0); |
569 | if (unlikely(ret < 0)) |
570 | return ret; |
571 | |
572 | iorw->bytes_done = 0; |
573 | iorw->free_iovec = iov; |
574 | if (iov) |
575 | req->flags |= REQ_F_NEED_CLEANUP; |
576 | return 0; |
577 | } |
578 | |
579 | int io_readv_prep_async(struct io_kiocb *req) |
580 | { |
581 | return io_rw_prep_async(req, ITER_DEST); |
582 | } |
583 | |
584 | int io_writev_prep_async(struct io_kiocb *req) |
585 | { |
586 | return io_rw_prep_async(req, ITER_SOURCE); |
587 | } |
588 | |
589 | /* |
590 | * This is our waitqueue callback handler, registered through __folio_lock_async() |
591 | * when we initially tried to do the IO with the iocb armed our waitqueue. |
592 | * This gets called when the page is unlocked, and we generally expect that to |
593 | * happen when the page IO is completed and the page is now uptodate. This will |
594 | * queue a task_work based retry of the operation, attempting to copy the data |
595 | * again. If the latter fails because the page was NOT uptodate, then we will |
596 | * do a thread based blocking retry of the operation. That's the unexpected |
597 | * slow path. |
598 | */ |
599 | static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode, |
600 | int sync, void *arg) |
601 | { |
602 | struct wait_page_queue *wpq; |
603 | struct io_kiocb *req = wait->private; |
604 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
605 | struct wait_page_key *key = arg; |
606 | |
607 | wpq = container_of(wait, struct wait_page_queue, wait); |
608 | |
609 | if (!wake_page_match(wait_page: wpq, key)) |
610 | return 0; |
611 | |
612 | rw->kiocb.ki_flags &= ~IOCB_WAITQ; |
613 | list_del_init(entry: &wait->entry); |
614 | io_req_task_queue(req); |
615 | return 1; |
616 | } |
617 | |
618 | /* |
619 | * This controls whether a given IO request should be armed for async page |
620 | * based retry. If we return false here, the request is handed to the async |
621 | * worker threads for retry. If we're doing buffered reads on a regular file, |
622 | * we prepare a private wait_page_queue entry and retry the operation. This |
623 | * will either succeed because the page is now uptodate and unlocked, or it |
624 | * will register a callback when the page is unlocked at IO completion. Through |
625 | * that callback, io_uring uses task_work to setup a retry of the operation. |
626 | * That retry will attempt the buffered read again. The retry will generally |
627 | * succeed, or in rare cases where it fails, we then fall back to using the |
628 | * async worker threads for a blocking retry. |
629 | */ |
630 | static bool io_rw_should_retry(struct io_kiocb *req) |
631 | { |
632 | struct io_async_rw *io = req->async_data; |
633 | struct wait_page_queue *wait = &io->wpq; |
634 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
635 | struct kiocb *kiocb = &rw->kiocb; |
636 | |
637 | /* never retry for NOWAIT, we just complete with -EAGAIN */ |
638 | if (req->flags & REQ_F_NOWAIT) |
639 | return false; |
640 | |
641 | /* Only for buffered IO */ |
642 | if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI)) |
643 | return false; |
644 | |
645 | /* |
646 | * just use poll if we can, and don't attempt if the fs doesn't |
647 | * support callback based unlocks |
648 | */ |
649 | if (file_can_poll(file: req->file) || !(req->file->f_mode & FMODE_BUF_RASYNC)) |
650 | return false; |
651 | |
652 | wait->wait.func = io_async_buf_func; |
653 | wait->wait.private = req; |
654 | wait->wait.flags = 0; |
655 | INIT_LIST_HEAD(list: &wait->wait.entry); |
656 | kiocb->ki_flags |= IOCB_WAITQ; |
657 | kiocb->ki_flags &= ~IOCB_NOWAIT; |
658 | kiocb->ki_waitq = wait; |
659 | return true; |
660 | } |
661 | |
662 | static inline int io_iter_do_read(struct io_rw *rw, struct iov_iter *iter) |
663 | { |
664 | struct file *file = rw->kiocb.ki_filp; |
665 | |
666 | if (likely(file->f_op->read_iter)) |
667 | return call_read_iter(file, kio: &rw->kiocb, iter); |
668 | else if (file->f_op->read) |
669 | return loop_rw_iter(READ, rw, iter); |
670 | else |
671 | return -EINVAL; |
672 | } |
673 | |
674 | static bool need_complete_io(struct io_kiocb *req) |
675 | { |
676 | return req->flags & REQ_F_ISREG || |
677 | S_ISBLK(file_inode(req->file)->i_mode); |
678 | } |
679 | |
680 | static int io_rw_init_file(struct io_kiocb *req, fmode_t mode) |
681 | { |
682 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
683 | struct kiocb *kiocb = &rw->kiocb; |
684 | struct io_ring_ctx *ctx = req->ctx; |
685 | struct file *file = req->file; |
686 | int ret; |
687 | |
688 | if (unlikely(!file || !(file->f_mode & mode))) |
689 | return -EBADF; |
690 | |
691 | if (!(req->flags & REQ_F_FIXED_FILE)) |
692 | req->flags |= io_file_get_flags(file); |
693 | |
694 | kiocb->ki_flags = file->f_iocb_flags; |
695 | ret = kiocb_set_rw_flags(ki: kiocb, flags: rw->flags); |
696 | if (unlikely(ret)) |
697 | return ret; |
698 | kiocb->ki_flags |= IOCB_ALLOC_CACHE; |
699 | |
700 | /* |
701 | * If the file is marked O_NONBLOCK, still allow retry for it if it |
702 | * supports async. Otherwise it's impossible to use O_NONBLOCK files |
703 | * reliably. If not, or it IOCB_NOWAIT is set, don't retry. |
704 | */ |
705 | if ((kiocb->ki_flags & IOCB_NOWAIT) || |
706 | ((file->f_flags & O_NONBLOCK) && !io_file_supports_nowait(req))) |
707 | req->flags |= REQ_F_NOWAIT; |
708 | |
709 | if (ctx->flags & IORING_SETUP_IOPOLL) { |
710 | if (!(kiocb->ki_flags & IOCB_DIRECT) || !file->f_op->iopoll) |
711 | return -EOPNOTSUPP; |
712 | |
713 | kiocb->private = NULL; |
714 | kiocb->ki_flags |= IOCB_HIPRI; |
715 | kiocb->ki_complete = io_complete_rw_iopoll; |
716 | req->iopoll_completed = 0; |
717 | } else { |
718 | if (kiocb->ki_flags & IOCB_HIPRI) |
719 | return -EINVAL; |
720 | kiocb->ki_complete = io_complete_rw; |
721 | } |
722 | |
723 | return 0; |
724 | } |
725 | |
726 | static int __io_read(struct io_kiocb *req, unsigned int issue_flags) |
727 | { |
728 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
729 | struct io_rw_state __s, *s = &__s; |
730 | struct iovec *iovec; |
731 | struct kiocb *kiocb = &rw->kiocb; |
732 | bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; |
733 | struct io_async_rw *io; |
734 | ssize_t ret, ret2; |
735 | loff_t *ppos; |
736 | |
737 | if (!req_has_async_data(req)) { |
738 | ret = io_import_iovec(ITER_DEST, req, iovec: &iovec, s, issue_flags); |
739 | if (unlikely(ret < 0)) |
740 | return ret; |
741 | } else { |
742 | io = req->async_data; |
743 | s = &io->s; |
744 | |
745 | /* |
746 | * Safe and required to re-import if we're using provided |
747 | * buffers, as we dropped the selected one before retry. |
748 | */ |
749 | if (io_do_buffer_select(req)) { |
750 | ret = io_import_iovec(ITER_DEST, req, iovec: &iovec, s, issue_flags); |
751 | if (unlikely(ret < 0)) |
752 | return ret; |
753 | } |
754 | |
755 | /* |
756 | * We come here from an earlier attempt, restore our state to |
757 | * match in case it doesn't. It's cheap enough that we don't |
758 | * need to make this conditional. |
759 | */ |
760 | iov_iter_restore(i: &s->iter, state: &s->iter_state); |
761 | iovec = NULL; |
762 | } |
763 | ret = io_rw_init_file(req, FMODE_READ); |
764 | if (unlikely(ret)) { |
765 | kfree(objp: iovec); |
766 | return ret; |
767 | } |
768 | req->cqe.res = iov_iter_count(i: &s->iter); |
769 | |
770 | if (force_nonblock) { |
771 | /* If the file doesn't support async, just async punt */ |
772 | if (unlikely(!io_file_supports_nowait(req))) { |
773 | ret = io_setup_async_rw(req, iovec, s, force: true); |
774 | return ret ?: -EAGAIN; |
775 | } |
776 | kiocb->ki_flags |= IOCB_NOWAIT; |
777 | } else { |
778 | /* Ensure we clear previously set non-block flag */ |
779 | kiocb->ki_flags &= ~IOCB_NOWAIT; |
780 | } |
781 | |
782 | ppos = io_kiocb_update_pos(req); |
783 | |
784 | ret = rw_verify_area(READ, req->file, ppos, req->cqe.res); |
785 | if (unlikely(ret)) { |
786 | kfree(objp: iovec); |
787 | return ret; |
788 | } |
789 | |
790 | ret = io_iter_do_read(rw, iter: &s->iter); |
791 | |
792 | if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) { |
793 | req->flags &= ~REQ_F_REISSUE; |
794 | /* |
795 | * If we can poll, just do that. For a vectored read, we'll |
796 | * need to copy state first. |
797 | */ |
798 | if (file_can_poll(file: req->file) && !io_issue_defs[req->opcode].vectored) |
799 | return -EAGAIN; |
800 | /* IOPOLL retry should happen for io-wq threads */ |
801 | if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL)) |
802 | goto done; |
803 | /* no retry on NONBLOCK nor RWF_NOWAIT */ |
804 | if (req->flags & REQ_F_NOWAIT) |
805 | goto done; |
806 | ret = 0; |
807 | } else if (ret == -EIOCBQUEUED) { |
808 | if (iovec) |
809 | kfree(objp: iovec); |
810 | return IOU_ISSUE_SKIP_COMPLETE; |
811 | } else if (ret == req->cqe.res || ret <= 0 || !force_nonblock || |
812 | (req->flags & REQ_F_NOWAIT) || !need_complete_io(req)) { |
813 | /* read all, failed, already did sync or don't want to retry */ |
814 | goto done; |
815 | } |
816 | |
817 | /* |
818 | * Don't depend on the iter state matching what was consumed, or being |
819 | * untouched in case of error. Restore it and we'll advance it |
820 | * manually if we need to. |
821 | */ |
822 | iov_iter_restore(i: &s->iter, state: &s->iter_state); |
823 | |
824 | ret2 = io_setup_async_rw(req, iovec, s, force: true); |
825 | iovec = NULL; |
826 | if (ret2) { |
827 | ret = ret > 0 ? ret : ret2; |
828 | goto done; |
829 | } |
830 | |
831 | io = req->async_data; |
832 | s = &io->s; |
833 | /* |
834 | * Now use our persistent iterator and state, if we aren't already. |
835 | * We've restored and mapped the iter to match. |
836 | */ |
837 | |
838 | do { |
839 | /* |
840 | * We end up here because of a partial read, either from |
841 | * above or inside this loop. Advance the iter by the bytes |
842 | * that were consumed. |
843 | */ |
844 | iov_iter_advance(i: &s->iter, bytes: ret); |
845 | if (!iov_iter_count(i: &s->iter)) |
846 | break; |
847 | io->bytes_done += ret; |
848 | iov_iter_save_state(iter: &s->iter, state: &s->iter_state); |
849 | |
850 | /* if we can retry, do so with the callbacks armed */ |
851 | if (!io_rw_should_retry(req)) { |
852 | kiocb->ki_flags &= ~IOCB_WAITQ; |
853 | return -EAGAIN; |
854 | } |
855 | |
856 | req->cqe.res = iov_iter_count(i: &s->iter); |
857 | /* |
858 | * Now retry read with the IOCB_WAITQ parts set in the iocb. If |
859 | * we get -EIOCBQUEUED, then we'll get a notification when the |
860 | * desired page gets unlocked. We can also get a partial read |
861 | * here, and if we do, then just retry at the new offset. |
862 | */ |
863 | ret = io_iter_do_read(rw, iter: &s->iter); |
864 | if (ret == -EIOCBQUEUED) |
865 | return IOU_ISSUE_SKIP_COMPLETE; |
866 | /* we got some bytes, but not all. retry. */ |
867 | kiocb->ki_flags &= ~IOCB_WAITQ; |
868 | iov_iter_restore(i: &s->iter, state: &s->iter_state); |
869 | } while (ret > 0); |
870 | done: |
871 | /* it's faster to check here then delegate to kfree */ |
872 | if (iovec) |
873 | kfree(objp: iovec); |
874 | return ret; |
875 | } |
876 | |
877 | int io_read(struct io_kiocb *req, unsigned int issue_flags) |
878 | { |
879 | int ret; |
880 | |
881 | ret = __io_read(req, issue_flags); |
882 | if (ret >= 0) |
883 | return kiocb_done(req, ret, issue_flags); |
884 | |
885 | return ret; |
886 | } |
887 | |
888 | int io_read_mshot(struct io_kiocb *req, unsigned int issue_flags) |
889 | { |
890 | unsigned int cflags = 0; |
891 | int ret; |
892 | |
893 | /* |
894 | * Multishot MUST be used on a pollable file |
895 | */ |
896 | if (!file_can_poll(file: req->file)) |
897 | return -EBADFD; |
898 | |
899 | ret = __io_read(req, issue_flags); |
900 | |
901 | /* |
902 | * If we get -EAGAIN, recycle our buffer and just let normal poll |
903 | * handling arm it. |
904 | */ |
905 | if (ret == -EAGAIN) { |
906 | io_kbuf_recycle(req, issue_flags); |
907 | return -EAGAIN; |
908 | } |
909 | |
910 | /* |
911 | * Any successful return value will keep the multishot read armed. |
912 | */ |
913 | if (ret > 0) { |
914 | /* |
915 | * Put our buffer and post a CQE. If we fail to post a CQE, then |
916 | * jump to the termination path. This request is then done. |
917 | */ |
918 | cflags = io_put_kbuf(req, issue_flags); |
919 | |
920 | if (io_fill_cqe_req_aux(req, |
921 | defer: issue_flags & IO_URING_F_COMPLETE_DEFER, |
922 | res: ret, cflags: cflags | IORING_CQE_F_MORE)) { |
923 | if (issue_flags & IO_URING_F_MULTISHOT) |
924 | return IOU_ISSUE_SKIP_COMPLETE; |
925 | return -EAGAIN; |
926 | } |
927 | } |
928 | |
929 | /* |
930 | * Either an error, or we've hit overflow posting the CQE. For any |
931 | * multishot request, hitting overflow will terminate it. |
932 | */ |
933 | io_req_set_res(req, res: ret, cflags); |
934 | if (issue_flags & IO_URING_F_MULTISHOT) |
935 | return IOU_STOP_MULTISHOT; |
936 | return IOU_OK; |
937 | } |
938 | |
939 | int io_write(struct io_kiocb *req, unsigned int issue_flags) |
940 | { |
941 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
942 | struct io_rw_state __s, *s = &__s; |
943 | struct iovec *iovec; |
944 | struct kiocb *kiocb = &rw->kiocb; |
945 | bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; |
946 | ssize_t ret, ret2; |
947 | loff_t *ppos; |
948 | |
949 | if (!req_has_async_data(req)) { |
950 | ret = io_import_iovec(ITER_SOURCE, req, iovec: &iovec, s, issue_flags); |
951 | if (unlikely(ret < 0)) |
952 | return ret; |
953 | } else { |
954 | struct io_async_rw *io = req->async_data; |
955 | |
956 | s = &io->s; |
957 | iov_iter_restore(i: &s->iter, state: &s->iter_state); |
958 | iovec = NULL; |
959 | } |
960 | ret = io_rw_init_file(req, FMODE_WRITE); |
961 | if (unlikely(ret)) { |
962 | kfree(objp: iovec); |
963 | return ret; |
964 | } |
965 | req->cqe.res = iov_iter_count(i: &s->iter); |
966 | |
967 | if (force_nonblock) { |
968 | /* If the file doesn't support async, just async punt */ |
969 | if (unlikely(!io_file_supports_nowait(req))) |
970 | goto copy_iov; |
971 | |
972 | /* File path supports NOWAIT for non-direct_IO only for block devices. */ |
973 | if (!(kiocb->ki_flags & IOCB_DIRECT) && |
974 | !(kiocb->ki_filp->f_mode & FMODE_BUF_WASYNC) && |
975 | (req->flags & REQ_F_ISREG)) |
976 | goto copy_iov; |
977 | |
978 | kiocb->ki_flags |= IOCB_NOWAIT; |
979 | } else { |
980 | /* Ensure we clear previously set non-block flag */ |
981 | kiocb->ki_flags &= ~IOCB_NOWAIT; |
982 | } |
983 | |
984 | ppos = io_kiocb_update_pos(req); |
985 | |
986 | ret = rw_verify_area(WRITE, req->file, ppos, req->cqe.res); |
987 | if (unlikely(ret)) { |
988 | kfree(objp: iovec); |
989 | return ret; |
990 | } |
991 | |
992 | if (req->flags & REQ_F_ISREG) |
993 | kiocb_start_write(iocb: kiocb); |
994 | kiocb->ki_flags |= IOCB_WRITE; |
995 | |
996 | if (likely(req->file->f_op->write_iter)) |
997 | ret2 = call_write_iter(file: req->file, kio: kiocb, iter: &s->iter); |
998 | else if (req->file->f_op->write) |
999 | ret2 = loop_rw_iter(WRITE, rw, iter: &s->iter); |
1000 | else |
1001 | ret2 = -EINVAL; |
1002 | |
1003 | if (req->flags & REQ_F_REISSUE) { |
1004 | req->flags &= ~REQ_F_REISSUE; |
1005 | ret2 = -EAGAIN; |
1006 | } |
1007 | |
1008 | /* |
1009 | * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just |
1010 | * retry them without IOCB_NOWAIT. |
1011 | */ |
1012 | if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT)) |
1013 | ret2 = -EAGAIN; |
1014 | /* no retry on NONBLOCK nor RWF_NOWAIT */ |
1015 | if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT)) |
1016 | goto done; |
1017 | if (!force_nonblock || ret2 != -EAGAIN) { |
1018 | /* IOPOLL retry should happen for io-wq threads */ |
1019 | if (ret2 == -EAGAIN && (req->ctx->flags & IORING_SETUP_IOPOLL)) |
1020 | goto copy_iov; |
1021 | |
1022 | if (ret2 != req->cqe.res && ret2 >= 0 && need_complete_io(req)) { |
1023 | struct io_async_rw *io; |
1024 | |
1025 | trace_io_uring_short_write(ctx: req->ctx, fpos: kiocb->ki_pos - ret2, |
1026 | wanted: req->cqe.res, got: ret2); |
1027 | |
1028 | /* This is a partial write. The file pos has already been |
1029 | * updated, setup the async struct to complete the request |
1030 | * in the worker. Also update bytes_done to account for |
1031 | * the bytes already written. |
1032 | */ |
1033 | iov_iter_save_state(iter: &s->iter, state: &s->iter_state); |
1034 | ret = io_setup_async_rw(req, iovec, s, force: true); |
1035 | |
1036 | io = req->async_data; |
1037 | if (io) |
1038 | io->bytes_done += ret2; |
1039 | |
1040 | if (kiocb->ki_flags & IOCB_WRITE) |
1041 | io_req_end_write(req); |
1042 | return ret ? ret : -EAGAIN; |
1043 | } |
1044 | done: |
1045 | ret = kiocb_done(req, ret: ret2, issue_flags); |
1046 | } else { |
1047 | copy_iov: |
1048 | iov_iter_restore(i: &s->iter, state: &s->iter_state); |
1049 | ret = io_setup_async_rw(req, iovec, s, force: false); |
1050 | if (!ret) { |
1051 | if (kiocb->ki_flags & IOCB_WRITE) |
1052 | io_req_end_write(req); |
1053 | return -EAGAIN; |
1054 | } |
1055 | return ret; |
1056 | } |
1057 | /* it's reportedly faster than delegating the null check to kfree() */ |
1058 | if (iovec) |
1059 | kfree(objp: iovec); |
1060 | return ret; |
1061 | } |
1062 | |
1063 | void io_rw_fail(struct io_kiocb *req) |
1064 | { |
1065 | int res; |
1066 | |
1067 | res = io_fixup_rw_res(req, res: req->cqe.res); |
1068 | io_req_set_res(req, res, cflags: req->cqe.flags); |
1069 | } |
1070 | |
1071 | int io_do_iopoll(struct io_ring_ctx *ctx, bool force_nonspin) |
1072 | { |
1073 | struct io_wq_work_node *pos, *start, *prev; |
1074 | unsigned int poll_flags = 0; |
1075 | DEFINE_IO_COMP_BATCH(iob); |
1076 | int nr_events = 0; |
1077 | |
1078 | /* |
1079 | * Only spin for completions if we don't have multiple devices hanging |
1080 | * off our complete list. |
1081 | */ |
1082 | if (ctx->poll_multi_queue || force_nonspin) |
1083 | poll_flags |= BLK_POLL_ONESHOT; |
1084 | |
1085 | wq_list_for_each(pos, start, &ctx->iopoll_list) { |
1086 | struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list); |
1087 | struct file *file = req->file; |
1088 | int ret; |
1089 | |
1090 | /* |
1091 | * Move completed and retryable entries to our local lists. |
1092 | * If we find a request that requires polling, break out |
1093 | * and complete those lists first, if we have entries there. |
1094 | */ |
1095 | if (READ_ONCE(req->iopoll_completed)) |
1096 | break; |
1097 | |
1098 | if (req->opcode == IORING_OP_URING_CMD) { |
1099 | struct io_uring_cmd *ioucmd; |
1100 | |
1101 | ioucmd = io_kiocb_to_cmd(req, struct io_uring_cmd); |
1102 | ret = file->f_op->uring_cmd_iopoll(ioucmd, &iob, |
1103 | poll_flags); |
1104 | } else { |
1105 | struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); |
1106 | |
1107 | ret = file->f_op->iopoll(&rw->kiocb, &iob, poll_flags); |
1108 | } |
1109 | if (unlikely(ret < 0)) |
1110 | return ret; |
1111 | else if (ret) |
1112 | poll_flags |= BLK_POLL_ONESHOT; |
1113 | |
1114 | /* iopoll may have completed current req */ |
1115 | if (!rq_list_empty(iob.req_list) || |
1116 | READ_ONCE(req->iopoll_completed)) |
1117 | break; |
1118 | } |
1119 | |
1120 | if (!rq_list_empty(iob.req_list)) |
1121 | iob.complete(&iob); |
1122 | else if (!pos) |
1123 | return 0; |
1124 | |
1125 | prev = start; |
1126 | wq_list_for_each_resume(pos, prev) { |
1127 | struct io_kiocb *req = container_of(pos, struct io_kiocb, comp_list); |
1128 | |
1129 | /* order with io_complete_rw_iopoll(), e.g. ->result updates */ |
1130 | if (!smp_load_acquire(&req->iopoll_completed)) |
1131 | break; |
1132 | nr_events++; |
1133 | req->cqe.flags = io_put_kbuf(req, issue_flags: 0); |
1134 | } |
1135 | if (unlikely(!nr_events)) |
1136 | return 0; |
1137 | |
1138 | pos = start ? start->next : ctx->iopoll_list.first; |
1139 | wq_list_cut(list: &ctx->iopoll_list, last: prev, prev: start); |
1140 | |
1141 | if (WARN_ON_ONCE(!wq_list_empty(&ctx->submit_state.compl_reqs))) |
1142 | return 0; |
1143 | ctx->submit_state.compl_reqs.first = pos; |
1144 | __io_submit_flush_completions(ctx); |
1145 | return nr_events; |
1146 | } |
1147 | |