1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2010 Red Hat, Inc.
4 * Copyright (c) 2016-2025 Christoph Hellwig.
5 */
6 #include <linux/fscrypt.h>
7 #include <linux/pagemap.h>
8 #include <linux/iomap.h>
9 #include <linux/task_io_accounting_ops.h>
10 #include "internal.h"
11 #include "trace.h"
12
13 #include "../internal.h"
14
15 /*
16 * Private flags for iomap_dio, must not overlap with the public ones in
17 * iomap.h:
18 */
19 #define IOMAP_DIO_NO_INVALIDATE (1U << 25)
20 #define IOMAP_DIO_CALLER_COMP (1U << 26)
21 #define IOMAP_DIO_INLINE_COMP (1U << 27)
22 #define IOMAP_DIO_WRITE_THROUGH (1U << 28)
23 #define IOMAP_DIO_NEED_SYNC (1U << 29)
24 #define IOMAP_DIO_WRITE (1U << 30)
25 #define IOMAP_DIO_DIRTY (1U << 31)
26
27 /*
28 * Used for sub block zeroing in iomap_dio_zero()
29 */
30 #define IOMAP_ZERO_PAGE_SIZE (SZ_64K)
31 #define IOMAP_ZERO_PAGE_ORDER (get_order(IOMAP_ZERO_PAGE_SIZE))
32 static struct page *zero_page;
33
34 struct iomap_dio {
35 struct kiocb *iocb;
36 const struct iomap_dio_ops *dops;
37 loff_t i_size;
38 loff_t size;
39 atomic_t ref;
40 unsigned flags;
41 int error;
42 size_t done_before;
43 bool wait_for_completion;
44
45 union {
46 /* used during submission and for synchronous completion: */
47 struct {
48 struct iov_iter *iter;
49 struct task_struct *waiter;
50 } submit;
51
52 /* used for aio completion: */
53 struct {
54 struct work_struct work;
55 } aio;
56 };
57 };
58
iomap_dio_alloc_bio(const struct iomap_iter * iter,struct iomap_dio * dio,unsigned short nr_vecs,blk_opf_t opf)59 static struct bio *iomap_dio_alloc_bio(const struct iomap_iter *iter,
60 struct iomap_dio *dio, unsigned short nr_vecs, blk_opf_t opf)
61 {
62 if (dio->dops && dio->dops->bio_set)
63 return bio_alloc_bioset(iter->iomap.bdev, nr_vecs, opf,
64 GFP_KERNEL, dio->dops->bio_set);
65 return bio_alloc(iter->iomap.bdev, nr_vecs, opf, GFP_KERNEL);
66 }
67
iomap_dio_submit_bio(const struct iomap_iter * iter,struct iomap_dio * dio,struct bio * bio,loff_t pos)68 static void iomap_dio_submit_bio(const struct iomap_iter *iter,
69 struct iomap_dio *dio, struct bio *bio, loff_t pos)
70 {
71 struct kiocb *iocb = dio->iocb;
72
73 atomic_inc(&dio->ref);
74
75 /* Sync dio can't be polled reliably */
76 if ((iocb->ki_flags & IOCB_HIPRI) && !is_sync_kiocb(iocb)) {
77 bio_set_polled(bio, iocb);
78 WRITE_ONCE(iocb->private, bio);
79 }
80
81 if (dio->dops && dio->dops->submit_io) {
82 dio->dops->submit_io(iter, bio, pos);
83 } else {
84 WARN_ON_ONCE(iter->iomap.flags & IOMAP_F_ANON_WRITE);
85 submit_bio(bio);
86 }
87 }
88
iomap_dio_complete(struct iomap_dio * dio)89 ssize_t iomap_dio_complete(struct iomap_dio *dio)
90 {
91 const struct iomap_dio_ops *dops = dio->dops;
92 struct kiocb *iocb = dio->iocb;
93 loff_t offset = iocb->ki_pos;
94 ssize_t ret = dio->error;
95
96 if (dops && dops->end_io)
97 ret = dops->end_io(iocb, dio->size, ret, dio->flags);
98
99 if (likely(!ret)) {
100 ret = dio->size;
101 /* check for short read */
102 if (offset + ret > dio->i_size &&
103 !(dio->flags & IOMAP_DIO_WRITE))
104 ret = dio->i_size - offset;
105 }
106
107 /*
108 * Try again to invalidate clean pages which might have been cached by
109 * non-direct readahead, or faulted in by get_user_pages() if the source
110 * of the write was an mmap'ed region of the file we're writing. Either
111 * one is a pretty crazy thing to do, so we don't support it 100%. If
112 * this invalidation fails, tough, the write still worked...
113 *
114 * And this page cache invalidation has to be after ->end_io(), as some
115 * filesystems convert unwritten extents to real allocations in
116 * ->end_io() when necessary, otherwise a racing buffer read would cache
117 * zeros from unwritten extents.
118 */
119 if (!dio->error && dio->size && (dio->flags & IOMAP_DIO_WRITE) &&
120 !(dio->flags & IOMAP_DIO_NO_INVALIDATE))
121 kiocb_invalidate_post_direct_write(iocb, dio->size);
122
123 inode_dio_end(file_inode(iocb->ki_filp));
124
125 if (ret > 0) {
126 iocb->ki_pos += ret;
127
128 /*
129 * If this is a DSYNC write, make sure we push it to stable
130 * storage now that we've written data.
131 */
132 if (dio->flags & IOMAP_DIO_NEED_SYNC)
133 ret = generic_write_sync(iocb, ret);
134 if (ret > 0)
135 ret += dio->done_before;
136 }
137 trace_iomap_dio_complete(iocb, dio->error, ret);
138 kfree(dio);
139 return ret;
140 }
141 EXPORT_SYMBOL_GPL(iomap_dio_complete);
142
iomap_dio_deferred_complete(void * data)143 static ssize_t iomap_dio_deferred_complete(void *data)
144 {
145 return iomap_dio_complete(data);
146 }
147
iomap_dio_complete_work(struct work_struct * work)148 static void iomap_dio_complete_work(struct work_struct *work)
149 {
150 struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
151 struct kiocb *iocb = dio->iocb;
152
153 iocb->ki_complete(iocb, iomap_dio_complete(dio));
154 }
155
156 /*
157 * Set an error in the dio if none is set yet. We have to use cmpxchg
158 * as the submission context and the completion context(s) can race to
159 * update the error.
160 */
iomap_dio_set_error(struct iomap_dio * dio,int ret)161 static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
162 {
163 cmpxchg(&dio->error, 0, ret);
164 }
165
166 /*
167 * Called when dio->ref reaches zero from an I/O completion.
168 */
iomap_dio_done(struct iomap_dio * dio)169 static void iomap_dio_done(struct iomap_dio *dio)
170 {
171 struct kiocb *iocb = dio->iocb;
172
173 if (dio->wait_for_completion) {
174 /*
175 * Synchronous I/O, task itself will handle any completion work
176 * that needs after IO. All we need to do is wake the task.
177 */
178 struct task_struct *waiter = dio->submit.waiter;
179
180 WRITE_ONCE(dio->submit.waiter, NULL);
181 blk_wake_io_task(waiter);
182 } else if (dio->flags & IOMAP_DIO_INLINE_COMP) {
183 WRITE_ONCE(iocb->private, NULL);
184 iomap_dio_complete_work(&dio->aio.work);
185 } else if (dio->flags & IOMAP_DIO_CALLER_COMP) {
186 /*
187 * If this dio is flagged with IOMAP_DIO_CALLER_COMP, then
188 * schedule our completion that way to avoid an async punt to a
189 * workqueue.
190 */
191 /* only polled IO cares about private cleared */
192 iocb->private = dio;
193 iocb->dio_complete = iomap_dio_deferred_complete;
194
195 /*
196 * Invoke ->ki_complete() directly. We've assigned our
197 * dio_complete callback handler, and since the issuer set
198 * IOCB_DIO_CALLER_COMP, we know their ki_complete handler will
199 * notice ->dio_complete being set and will defer calling that
200 * handler until it can be done from a safe task context.
201 *
202 * Note that the 'res' being passed in here is not important
203 * for this case. The actual completion value of the request
204 * will be gotten from dio_complete when that is run by the
205 * issuer.
206 */
207 iocb->ki_complete(iocb, 0);
208 } else {
209 struct inode *inode = file_inode(iocb->ki_filp);
210
211 /*
212 * Async DIO completion that requires filesystem level
213 * completion work gets punted to a work queue to complete as
214 * the operation may require more IO to be issued to finalise
215 * filesystem metadata changes or guarantee data integrity.
216 */
217 INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
218 queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
219 }
220 }
221
iomap_dio_bio_end_io(struct bio * bio)222 void iomap_dio_bio_end_io(struct bio *bio)
223 {
224 struct iomap_dio *dio = bio->bi_private;
225 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
226
227 if (bio->bi_status)
228 iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
229
230 if (atomic_dec_and_test(&dio->ref))
231 iomap_dio_done(dio);
232
233 if (should_dirty) {
234 bio_check_pages_dirty(bio);
235 } else {
236 bio_release_pages(bio, false);
237 bio_put(bio);
238 }
239 }
240 EXPORT_SYMBOL_GPL(iomap_dio_bio_end_io);
241
iomap_finish_ioend_direct(struct iomap_ioend * ioend)242 u32 iomap_finish_ioend_direct(struct iomap_ioend *ioend)
243 {
244 struct iomap_dio *dio = ioend->io_bio.bi_private;
245 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
246 u32 vec_count = ioend->io_bio.bi_vcnt;
247
248 if (ioend->io_error)
249 iomap_dio_set_error(dio, ioend->io_error);
250
251 if (atomic_dec_and_test(&dio->ref)) {
252 /*
253 * Try to avoid another context switch for the completion given
254 * that we are already called from the ioend completion
255 * workqueue, but never invalidate pages from this thread to
256 * avoid deadlocks with buffered I/O completions. Tough luck if
257 * you hit the tiny race with someone dirtying the range now
258 * between this check and the actual completion.
259 */
260 if (!dio->iocb->ki_filp->f_mapping->nrpages) {
261 dio->flags |= IOMAP_DIO_INLINE_COMP;
262 dio->flags |= IOMAP_DIO_NO_INVALIDATE;
263 }
264 dio->flags &= ~IOMAP_DIO_CALLER_COMP;
265 iomap_dio_done(dio);
266 }
267
268 if (should_dirty) {
269 bio_check_pages_dirty(&ioend->io_bio);
270 } else {
271 bio_release_pages(&ioend->io_bio, false);
272 bio_put(&ioend->io_bio);
273 }
274
275 /*
276 * Return the number of bvecs completed as even direct I/O completions
277 * do significant per-folio work and we'll still want to give up the
278 * CPU after a lot of completions.
279 */
280 return vec_count;
281 }
282
iomap_dio_zero(const struct iomap_iter * iter,struct iomap_dio * dio,loff_t pos,unsigned len)283 static int iomap_dio_zero(const struct iomap_iter *iter, struct iomap_dio *dio,
284 loff_t pos, unsigned len)
285 {
286 struct inode *inode = file_inode(dio->iocb->ki_filp);
287 struct bio *bio;
288
289 if (!len)
290 return 0;
291 /*
292 * Max block size supported is 64k
293 */
294 if (WARN_ON_ONCE(len > IOMAP_ZERO_PAGE_SIZE))
295 return -EINVAL;
296
297 bio = iomap_dio_alloc_bio(iter, dio, 1, REQ_OP_WRITE | REQ_SYNC | REQ_IDLE);
298 fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
299 GFP_KERNEL);
300 bio->bi_iter.bi_sector = iomap_sector(&iter->iomap, pos);
301 bio->bi_private = dio;
302 bio->bi_end_io = iomap_dio_bio_end_io;
303
304 __bio_add_page(bio, zero_page, len, 0);
305 iomap_dio_submit_bio(iter, dio, bio, pos);
306 return 0;
307 }
308
309 /*
310 * Use a FUA write if we need datasync semantics and this is a pure data I/O
311 * that doesn't require any metadata updates (including after I/O completion
312 * such as unwritten extent conversion) and the underlying device either
313 * doesn't have a volatile write cache or supports FUA.
314 * This allows us to avoid cache flushes on I/O completion.
315 */
iomap_dio_can_use_fua(const struct iomap * iomap,struct iomap_dio * dio)316 static inline bool iomap_dio_can_use_fua(const struct iomap *iomap,
317 struct iomap_dio *dio)
318 {
319 if (iomap->flags & (IOMAP_F_SHARED | IOMAP_F_DIRTY))
320 return false;
321 if (!(dio->flags & IOMAP_DIO_WRITE_THROUGH))
322 return false;
323 return !bdev_write_cache(iomap->bdev) || bdev_fua(iomap->bdev);
324 }
325
iomap_dio_bio_iter(struct iomap_iter * iter,struct iomap_dio * dio)326 static int iomap_dio_bio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
327 {
328 const struct iomap *iomap = &iter->iomap;
329 struct inode *inode = iter->inode;
330 unsigned int fs_block_size = i_blocksize(inode), pad;
331 const loff_t length = iomap_length(iter);
332 loff_t pos = iter->pos;
333 blk_opf_t bio_opf = REQ_SYNC | REQ_IDLE;
334 struct bio *bio;
335 bool need_zeroout = false;
336 int nr_pages, ret = 0;
337 u64 copied = 0;
338 size_t orig_count;
339
340 if ((pos | length) & (bdev_logical_block_size(iomap->bdev) - 1) ||
341 !bdev_iter_is_aligned(iomap->bdev, dio->submit.iter))
342 return -EINVAL;
343
344 if (dio->flags & IOMAP_DIO_WRITE) {
345 bio_opf |= REQ_OP_WRITE;
346
347 if (iomap->flags & IOMAP_F_ATOMIC_BIO) {
348 /*
349 * Ensure that the mapping covers the full write
350 * length, otherwise it won't be submitted as a single
351 * bio, which is required to use hardware atomics.
352 */
353 if (length != iter->len)
354 return -EINVAL;
355 bio_opf |= REQ_ATOMIC;
356 }
357
358 if (iomap->type == IOMAP_UNWRITTEN) {
359 dio->flags |= IOMAP_DIO_UNWRITTEN;
360 need_zeroout = true;
361 }
362
363 if (iomap->flags & IOMAP_F_SHARED)
364 dio->flags |= IOMAP_DIO_COW;
365
366 if (iomap->flags & IOMAP_F_NEW) {
367 need_zeroout = true;
368 } else if (iomap->type == IOMAP_MAPPED) {
369 if (iomap_dio_can_use_fua(iomap, dio))
370 bio_opf |= REQ_FUA;
371 else
372 dio->flags &= ~IOMAP_DIO_WRITE_THROUGH;
373 }
374
375 /*
376 * We can only do deferred completion for pure overwrites that
377 * don't require additional I/O at completion time.
378 *
379 * This rules out writes that need zeroing or extent conversion,
380 * extend the file size, or issue metadata I/O or cache flushes
381 * during completion processing.
382 */
383 if (need_zeroout || (pos >= i_size_read(inode)) ||
384 ((dio->flags & IOMAP_DIO_NEED_SYNC) &&
385 !(bio_opf & REQ_FUA)))
386 dio->flags &= ~IOMAP_DIO_CALLER_COMP;
387 } else {
388 bio_opf |= REQ_OP_READ;
389 }
390
391 /*
392 * Save the original count and trim the iter to just the extent we
393 * are operating on right now. The iter will be re-expanded once
394 * we are done.
395 */
396 orig_count = iov_iter_count(dio->submit.iter);
397 iov_iter_truncate(dio->submit.iter, length);
398
399 if (!iov_iter_count(dio->submit.iter))
400 goto out;
401
402 /*
403 * The rules for polled IO completions follow the guidelines as the
404 * ones we set for inline and deferred completions. If none of those
405 * are available for this IO, clear the polled flag.
406 */
407 if (!(dio->flags & (IOMAP_DIO_INLINE_COMP|IOMAP_DIO_CALLER_COMP)))
408 dio->iocb->ki_flags &= ~IOCB_HIPRI;
409
410 if (need_zeroout) {
411 /* zero out from the start of the block to the write offset */
412 pad = pos & (fs_block_size - 1);
413
414 ret = iomap_dio_zero(iter, dio, pos - pad, pad);
415 if (ret)
416 goto out;
417 }
418
419 nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter, BIO_MAX_VECS);
420 do {
421 size_t n;
422 if (dio->error) {
423 iov_iter_revert(dio->submit.iter, copied);
424 copied = ret = 0;
425 goto out;
426 }
427
428 bio = iomap_dio_alloc_bio(iter, dio, nr_pages, bio_opf);
429 fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits,
430 GFP_KERNEL);
431 bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
432 bio->bi_write_hint = inode->i_write_hint;
433 bio->bi_ioprio = dio->iocb->ki_ioprio;
434 bio->bi_private = dio;
435 bio->bi_end_io = iomap_dio_bio_end_io;
436
437 ret = bio_iov_iter_get_pages(bio, dio->submit.iter);
438 if (unlikely(ret)) {
439 /*
440 * We have to stop part way through an IO. We must fall
441 * through to the sub-block tail zeroing here, otherwise
442 * this short IO may expose stale data in the tail of
443 * the block we haven't written data to.
444 */
445 bio_put(bio);
446 goto zero_tail;
447 }
448
449 n = bio->bi_iter.bi_size;
450 if (WARN_ON_ONCE((bio_opf & REQ_ATOMIC) && n != length)) {
451 /*
452 * An atomic write bio must cover the complete length,
453 * which it doesn't, so error. We may need to zero out
454 * the tail (complete FS block), similar to when
455 * bio_iov_iter_get_pages() returns an error, above.
456 */
457 ret = -EINVAL;
458 bio_put(bio);
459 goto zero_tail;
460 }
461 if (dio->flags & IOMAP_DIO_WRITE)
462 task_io_account_write(n);
463 else if (dio->flags & IOMAP_DIO_DIRTY)
464 bio_set_pages_dirty(bio);
465
466 dio->size += n;
467 copied += n;
468
469 nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter,
470 BIO_MAX_VECS);
471 /*
472 * We can only poll for single bio I/Os.
473 */
474 if (nr_pages)
475 dio->iocb->ki_flags &= ~IOCB_HIPRI;
476 iomap_dio_submit_bio(iter, dio, bio, pos);
477 pos += n;
478 } while (nr_pages);
479
480 /*
481 * We need to zeroout the tail of a sub-block write if the extent type
482 * requires zeroing or the write extends beyond EOF. If we don't zero
483 * the block tail in the latter case, we can expose stale data via mmap
484 * reads of the EOF block.
485 */
486 zero_tail:
487 if (need_zeroout ||
488 ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
489 /* zero out from the end of the write to the end of the block */
490 pad = pos & (fs_block_size - 1);
491 if (pad)
492 ret = iomap_dio_zero(iter, dio, pos,
493 fs_block_size - pad);
494 }
495 out:
496 /* Undo iter limitation to current extent */
497 iov_iter_reexpand(dio->submit.iter, orig_count - copied);
498 if (copied)
499 return iomap_iter_advance(iter, &copied);
500 return ret;
501 }
502
iomap_dio_hole_iter(struct iomap_iter * iter,struct iomap_dio * dio)503 static int iomap_dio_hole_iter(struct iomap_iter *iter, struct iomap_dio *dio)
504 {
505 loff_t length = iov_iter_zero(iomap_length(iter), dio->submit.iter);
506
507 dio->size += length;
508 if (!length)
509 return -EFAULT;
510 return iomap_iter_advance(iter, &length);
511 }
512
iomap_dio_inline_iter(struct iomap_iter * iomi,struct iomap_dio * dio)513 static int iomap_dio_inline_iter(struct iomap_iter *iomi, struct iomap_dio *dio)
514 {
515 const struct iomap *iomap = &iomi->iomap;
516 struct iov_iter *iter = dio->submit.iter;
517 void *inline_data = iomap_inline_data(iomap, iomi->pos);
518 loff_t length = iomap_length(iomi);
519 loff_t pos = iomi->pos;
520 u64 copied;
521
522 if (WARN_ON_ONCE(!iomap_inline_data_valid(iomap)))
523 return -EIO;
524
525 if (dio->flags & IOMAP_DIO_WRITE) {
526 loff_t size = iomi->inode->i_size;
527
528 if (pos > size)
529 memset(iomap_inline_data(iomap, size), 0, pos - size);
530 copied = copy_from_iter(inline_data, length, iter);
531 if (copied) {
532 if (pos + copied > size)
533 i_size_write(iomi->inode, pos + copied);
534 mark_inode_dirty(iomi->inode);
535 }
536 } else {
537 copied = copy_to_iter(inline_data, length, iter);
538 }
539 dio->size += copied;
540 if (!copied)
541 return -EFAULT;
542 return iomap_iter_advance(iomi, &copied);
543 }
544
iomap_dio_iter(struct iomap_iter * iter,struct iomap_dio * dio)545 static int iomap_dio_iter(struct iomap_iter *iter, struct iomap_dio *dio)
546 {
547 switch (iter->iomap.type) {
548 case IOMAP_HOLE:
549 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
550 return -EIO;
551 return iomap_dio_hole_iter(iter, dio);
552 case IOMAP_UNWRITTEN:
553 if (!(dio->flags & IOMAP_DIO_WRITE))
554 return iomap_dio_hole_iter(iter, dio);
555 return iomap_dio_bio_iter(iter, dio);
556 case IOMAP_MAPPED:
557 return iomap_dio_bio_iter(iter, dio);
558 case IOMAP_INLINE:
559 return iomap_dio_inline_iter(iter, dio);
560 case IOMAP_DELALLOC:
561 /*
562 * DIO is not serialised against mmap() access at all, and so
563 * if the page_mkwrite occurs between the writeback and the
564 * iomap_iter() call in the DIO path, then it will see the
565 * DELALLOC block that the page-mkwrite allocated.
566 */
567 pr_warn_ratelimited("Direct I/O collision with buffered writes! File: %pD4 Comm: %.20s\n",
568 dio->iocb->ki_filp, current->comm);
569 return -EIO;
570 default:
571 WARN_ON_ONCE(1);
572 return -EIO;
573 }
574 }
575
576 /*
577 * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
578 * is being issued as AIO or not. This allows us to optimise pure data writes
579 * to use REQ_FUA rather than requiring generic_write_sync() to issue a
580 * REQ_FLUSH post write. This is slightly tricky because a single request here
581 * can be mapped into multiple disjoint IOs and only a subset of the IOs issued
582 * may be pure data writes. In that case, we still need to do a full data sync
583 * completion.
584 *
585 * When page faults are disabled and @dio_flags includes IOMAP_DIO_PARTIAL,
586 * __iomap_dio_rw can return a partial result if it encounters a non-resident
587 * page in @iter after preparing a transfer. In that case, the non-resident
588 * pages can be faulted in and the request resumed with @done_before set to the
589 * number of bytes previously transferred. The request will then complete with
590 * the correct total number of bytes transferred; this is essential for
591 * completing partial requests asynchronously.
592 *
593 * Returns -ENOTBLK In case of a page invalidation invalidation failure for
594 * writes. The callers needs to fall back to buffered I/O in this case.
595 */
596 struct iomap_dio *
__iomap_dio_rw(struct kiocb * iocb,struct iov_iter * iter,const struct iomap_ops * ops,const struct iomap_dio_ops * dops,unsigned int dio_flags,void * private,size_t done_before)597 __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
598 const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
599 unsigned int dio_flags, void *private, size_t done_before)
600 {
601 struct inode *inode = file_inode(iocb->ki_filp);
602 struct iomap_iter iomi = {
603 .inode = inode,
604 .pos = iocb->ki_pos,
605 .len = iov_iter_count(iter),
606 .flags = IOMAP_DIRECT,
607 .private = private,
608 };
609 bool wait_for_completion =
610 is_sync_kiocb(iocb) || (dio_flags & IOMAP_DIO_FORCE_WAIT);
611 struct blk_plug plug;
612 struct iomap_dio *dio;
613 loff_t ret = 0;
614
615 trace_iomap_dio_rw_begin(iocb, iter, dio_flags, done_before);
616
617 if (!iomi.len)
618 return NULL;
619
620 dio = kmalloc(sizeof(*dio), GFP_KERNEL);
621 if (!dio)
622 return ERR_PTR(-ENOMEM);
623
624 dio->iocb = iocb;
625 atomic_set(&dio->ref, 1);
626 dio->size = 0;
627 dio->i_size = i_size_read(inode);
628 dio->dops = dops;
629 dio->error = 0;
630 dio->flags = 0;
631 dio->done_before = done_before;
632
633 dio->submit.iter = iter;
634 dio->submit.waiter = current;
635
636 if (iocb->ki_flags & IOCB_NOWAIT)
637 iomi.flags |= IOMAP_NOWAIT;
638
639 if (iov_iter_rw(iter) == READ) {
640 /* reads can always complete inline */
641 dio->flags |= IOMAP_DIO_INLINE_COMP;
642
643 if (iomi.pos >= dio->i_size)
644 goto out_free_dio;
645
646 if (user_backed_iter(iter))
647 dio->flags |= IOMAP_DIO_DIRTY;
648
649 ret = kiocb_write_and_wait(iocb, iomi.len);
650 if (ret)
651 goto out_free_dio;
652 } else {
653 iomi.flags |= IOMAP_WRITE;
654 dio->flags |= IOMAP_DIO_WRITE;
655
656 /*
657 * Flag as supporting deferred completions, if the issuer
658 * groks it. This can avoid a workqueue punt for writes.
659 * We may later clear this flag if we need to do other IO
660 * as part of this IO completion.
661 */
662 if (iocb->ki_flags & IOCB_DIO_CALLER_COMP)
663 dio->flags |= IOMAP_DIO_CALLER_COMP;
664
665 if (dio_flags & IOMAP_DIO_OVERWRITE_ONLY) {
666 ret = -EAGAIN;
667 if (iomi.pos >= dio->i_size ||
668 iomi.pos + iomi.len > dio->i_size)
669 goto out_free_dio;
670 iomi.flags |= IOMAP_OVERWRITE_ONLY;
671 }
672
673 if (iocb->ki_flags & IOCB_ATOMIC)
674 iomi.flags |= IOMAP_ATOMIC;
675
676 /* for data sync or sync, we need sync completion processing */
677 if (iocb_is_dsync(iocb)) {
678 dio->flags |= IOMAP_DIO_NEED_SYNC;
679
680 /*
681 * For datasync only writes, we optimistically try using
682 * WRITE_THROUGH for this IO. This flag requires either
683 * FUA writes through the device's write cache, or a
684 * normal write to a device without a volatile write
685 * cache. For the former, Any non-FUA write that occurs
686 * will clear this flag, hence we know before completion
687 * whether a cache flush is necessary.
688 */
689 if (!(iocb->ki_flags & IOCB_SYNC))
690 dio->flags |= IOMAP_DIO_WRITE_THROUGH;
691 }
692
693 /*
694 * Try to invalidate cache pages for the range we are writing.
695 * If this invalidation fails, let the caller fall back to
696 * buffered I/O.
697 */
698 ret = kiocb_invalidate_pages(iocb, iomi.len);
699 if (ret) {
700 if (ret != -EAGAIN) {
701 trace_iomap_dio_invalidate_fail(inode, iomi.pos,
702 iomi.len);
703 if (iocb->ki_flags & IOCB_ATOMIC) {
704 /*
705 * folio invalidation failed, maybe
706 * this is transient, unlock and see if
707 * the caller tries again.
708 */
709 ret = -EAGAIN;
710 } else {
711 /* fall back to buffered write */
712 ret = -ENOTBLK;
713 }
714 }
715 goto out_free_dio;
716 }
717
718 if (!wait_for_completion && !inode->i_sb->s_dio_done_wq) {
719 ret = sb_init_dio_done_wq(inode->i_sb);
720 if (ret < 0)
721 goto out_free_dio;
722 }
723 }
724
725 inode_dio_begin(inode);
726
727 blk_start_plug(&plug);
728 while ((ret = iomap_iter(&iomi, ops)) > 0) {
729 iomi.status = iomap_dio_iter(&iomi, dio);
730
731 /*
732 * We can only poll for single bio I/Os.
733 */
734 iocb->ki_flags &= ~IOCB_HIPRI;
735 }
736
737 blk_finish_plug(&plug);
738
739 /*
740 * We only report that we've read data up to i_size.
741 * Revert iter to a state corresponding to that as some callers (such
742 * as the splice code) rely on it.
743 */
744 if (iov_iter_rw(iter) == READ && iomi.pos >= dio->i_size)
745 iov_iter_revert(iter, iomi.pos - dio->i_size);
746
747 if (ret == -EFAULT && dio->size && (dio_flags & IOMAP_DIO_PARTIAL)) {
748 if (!(iocb->ki_flags & IOCB_NOWAIT))
749 wait_for_completion = true;
750 ret = 0;
751 }
752
753 /* magic error code to fall back to buffered I/O */
754 if (ret == -ENOTBLK) {
755 wait_for_completion = true;
756 ret = 0;
757 }
758 if (ret < 0)
759 iomap_dio_set_error(dio, ret);
760
761 /*
762 * If all the writes we issued were already written through to the
763 * media, we don't need to flush the cache on IO completion. Clear the
764 * sync flag for this case.
765 */
766 if (dio->flags & IOMAP_DIO_WRITE_THROUGH)
767 dio->flags &= ~IOMAP_DIO_NEED_SYNC;
768
769 /*
770 * We are about to drop our additional submission reference, which
771 * might be the last reference to the dio. There are three different
772 * ways we can progress here:
773 *
774 * (a) If this is the last reference we will always complete and free
775 * the dio ourselves.
776 * (b) If this is not the last reference, and we serve an asynchronous
777 * iocb, we must never touch the dio after the decrement, the
778 * I/O completion handler will complete and free it.
779 * (c) If this is not the last reference, but we serve a synchronous
780 * iocb, the I/O completion handler will wake us up on the drop
781 * of the final reference, and we will complete and free it here
782 * after we got woken by the I/O completion handler.
783 */
784 dio->wait_for_completion = wait_for_completion;
785 if (!atomic_dec_and_test(&dio->ref)) {
786 if (!wait_for_completion) {
787 trace_iomap_dio_rw_queued(inode, iomi.pos, iomi.len);
788 return ERR_PTR(-EIOCBQUEUED);
789 }
790
791 for (;;) {
792 set_current_state(TASK_UNINTERRUPTIBLE);
793 if (!READ_ONCE(dio->submit.waiter))
794 break;
795
796 blk_io_schedule();
797 }
798 __set_current_state(TASK_RUNNING);
799 }
800
801 return dio;
802
803 out_free_dio:
804 kfree(dio);
805 if (ret)
806 return ERR_PTR(ret);
807 return NULL;
808 }
809 EXPORT_SYMBOL_GPL(__iomap_dio_rw);
810
811 ssize_t
iomap_dio_rw(struct kiocb * iocb,struct iov_iter * iter,const struct iomap_ops * ops,const struct iomap_dio_ops * dops,unsigned int dio_flags,void * private,size_t done_before)812 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
813 const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
814 unsigned int dio_flags, void *private, size_t done_before)
815 {
816 struct iomap_dio *dio;
817
818 dio = __iomap_dio_rw(iocb, iter, ops, dops, dio_flags, private,
819 done_before);
820 if (IS_ERR_OR_NULL(dio))
821 return PTR_ERR_OR_ZERO(dio);
822 return iomap_dio_complete(dio);
823 }
824 EXPORT_SYMBOL_GPL(iomap_dio_rw);
825
iomap_dio_init(void)826 static int __init iomap_dio_init(void)
827 {
828 zero_page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
829 IOMAP_ZERO_PAGE_ORDER);
830
831 if (!zero_page)
832 return -ENOMEM;
833
834 return 0;
835 }
836 fs_initcall(iomap_dio_init);
837