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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2010 Red Hat, Inc.
4 * Copyright (c) 2016-2018 Christoph Hellwig.
5 */
6#include <linux/module.h>
7#include <linux/compiler.h>
8#include <linux/fs.h>
9#include <linux/iomap.h>
10#include <linux/backing-dev.h>
11#include <linux/uio.h>
12#include <linux/task_io_accounting_ops.h>
13#include "trace.h"
14
15#include "../internal.h"
16
17/*
18 * Private flags for iomap_dio, must not overlap with the public ones in
19 * iomap.h:
20 */
21#define IOMAP_DIO_WRITE_FUA (1 << 28)
22#define IOMAP_DIO_NEED_SYNC (1 << 29)
23#define IOMAP_DIO_WRITE (1 << 30)
24#define IOMAP_DIO_DIRTY (1 << 31)
25
26struct iomap_dio {
27 struct kiocb *iocb;
28 const struct iomap_dio_ops *dops;
29 loff_t i_size;
30 loff_t size;
31 atomic_t ref;
32 unsigned flags;
33 int error;
34 bool wait_for_completion;
35
36 union {
37 /* used during submission and for synchronous completion: */
38 struct {
39 struct iov_iter *iter;
40 struct task_struct *waiter;
41 struct request_queue *last_queue;
42 blk_qc_t cookie;
43 } submit;
44
45 /* used for aio completion: */
46 struct {
47 struct work_struct work;
48 } aio;
49 };
50};
51
52int iomap_dio_iopoll(struct kiocb *kiocb, bool spin)
53{
54 struct request_queue *q = READ_ONCE(kiocb->private);
55
56 if (!q)
57 return 0;
58 return blk_poll(q, READ_ONCE(kiocb->ki_cookie), spin);
59}
60EXPORT_SYMBOL_GPL(iomap_dio_iopoll);
61
62static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
63 struct bio *bio, loff_t pos)
64{
65 atomic_inc(&dio->ref);
66
67 if (dio->iocb->ki_flags & IOCB_HIPRI)
68 bio_set_polled(bio, dio->iocb);
69
70 dio->submit.last_queue = bdev_get_queue(iomap->bdev);
71 if (dio->dops && dio->dops->submit_io)
72 dio->submit.cookie = dio->dops->submit_io(
73 file_inode(dio->iocb->ki_filp),
74 iomap, bio, pos);
75 else
76 dio->submit.cookie = submit_bio(bio);
77}
78
79static ssize_t iomap_dio_complete(struct iomap_dio *dio)
80{
81 const struct iomap_dio_ops *dops = dio->dops;
82 struct kiocb *iocb = dio->iocb;
83 struct inode *inode = file_inode(iocb->ki_filp);
84 loff_t offset = iocb->ki_pos;
85 ssize_t ret = dio->error;
86
87 if (dops && dops->end_io)
88 ret = dops->end_io(iocb, dio->size, ret, dio->flags);
89
90 if (likely(!ret)) {
91 ret = dio->size;
92 /* check for short read */
93 if (offset + ret > dio->i_size &&
94 !(dio->flags & IOMAP_DIO_WRITE))
95 ret = dio->i_size - offset;
96 iocb->ki_pos += ret;
97 }
98
99 /*
100 * Try again to invalidate clean pages which might have been cached by
101 * non-direct readahead, or faulted in by get_user_pages() if the source
102 * of the write was an mmap'ed region of the file we're writing. Either
103 * one is a pretty crazy thing to do, so we don't support it 100%. If
104 * this invalidation fails, tough, the write still worked...
105 *
106 * And this page cache invalidation has to be after ->end_io(), as some
107 * filesystems convert unwritten extents to real allocations in
108 * ->end_io() when necessary, otherwise a racing buffer read would cache
109 * zeros from unwritten extents.
110 */
111 if (!dio->error &&
112 (dio->flags & IOMAP_DIO_WRITE) && inode->i_mapping->nrpages) {
113 int err;
114 err = invalidate_inode_pages2_range(inode->i_mapping,
115 offset >> PAGE_SHIFT,
116 (offset + dio->size - 1) >> PAGE_SHIFT);
117 if (err)
118 dio_warn_stale_pagecache(iocb->ki_filp);
119 }
120
121 /*
122 * If this is a DSYNC write, make sure we push it to stable storage now
123 * that we've written data.
124 */
125 if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
126 ret = generic_write_sync(iocb, ret);
127
128 inode_dio_end(file_inode(iocb->ki_filp));
129 kfree(dio);
130
131 return ret;
132}
133
134static void iomap_dio_complete_work(struct work_struct *work)
135{
136 struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
137 struct kiocb *iocb = dio->iocb;
138
139 iocb->ki_complete(iocb, iomap_dio_complete(dio), 0);
140}
141
142/*
143 * Set an error in the dio if none is set yet. We have to use cmpxchg
144 * as the submission context and the completion context(s) can race to
145 * update the error.
146 */
147static inline void iomap_dio_set_error(struct iomap_dio *dio, int ret)
148{
149 cmpxchg(&dio->error, 0, ret);
150}
151
152static void iomap_dio_bio_end_io(struct bio *bio)
153{
154 struct iomap_dio *dio = bio->bi_private;
155 bool should_dirty = (dio->flags & IOMAP_DIO_DIRTY);
156
157 if (bio->bi_status)
158 iomap_dio_set_error(dio, blk_status_to_errno(bio->bi_status));
159
160 if (atomic_dec_and_test(&dio->ref)) {
161 if (dio->wait_for_completion) {
162 struct task_struct *waiter = dio->submit.waiter;
163 WRITE_ONCE(dio->submit.waiter, NULL);
164 blk_wake_io_task(waiter);
165 } else if (dio->flags & IOMAP_DIO_WRITE) {
166 struct inode *inode = file_inode(dio->iocb->ki_filp);
167
168 INIT_WORK(&dio->aio.work, iomap_dio_complete_work);
169 queue_work(inode->i_sb->s_dio_done_wq, &dio->aio.work);
170 } else {
171 iomap_dio_complete_work(&dio->aio.work);
172 }
173 }
174
175 if (should_dirty) {
176 bio_check_pages_dirty(bio);
177 } else {
178 bio_release_pages(bio, false);
179 bio_put(bio);
180 }
181}
182
183static void
184iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
185 unsigned len)
186{
187 struct page *page = ZERO_PAGE(0);
188 int flags = REQ_SYNC | REQ_IDLE;
189 struct bio *bio;
190
191 bio = bio_alloc(GFP_KERNEL, 1);
192 bio_set_dev(bio, iomap->bdev);
193 bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
194 bio->bi_private = dio;
195 bio->bi_end_io = iomap_dio_bio_end_io;
196
197 get_page(page);
198 __bio_add_page(bio, page, len, 0);
199 bio_set_op_attrs(bio, REQ_OP_WRITE, flags);
200 iomap_dio_submit_bio(dio, iomap, bio, pos);
201}
202
203static loff_t
204iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
205 struct iomap_dio *dio, struct iomap *iomap)
206{
207 unsigned int blkbits = blksize_bits(bdev_logical_block_size(iomap->bdev));
208 unsigned int fs_block_size = i_blocksize(inode), pad;
209 unsigned int align = iov_iter_alignment(dio->submit.iter);
210 struct bio *bio;
211 bool need_zeroout = false;
212 bool use_fua = false;
213 int nr_pages, ret = 0;
214 size_t copied = 0;
215 size_t orig_count;
216
217 if ((pos | length | align) & ((1 << blkbits) - 1))
218 return -EINVAL;
219
220 if (iomap->type == IOMAP_UNWRITTEN) {
221 dio->flags |= IOMAP_DIO_UNWRITTEN;
222 need_zeroout = true;
223 }
224
225 if (iomap->flags & IOMAP_F_SHARED)
226 dio->flags |= IOMAP_DIO_COW;
227
228 if (iomap->flags & IOMAP_F_NEW) {
229 need_zeroout = true;
230 } else if (iomap->type == IOMAP_MAPPED) {
231 /*
232 * Use a FUA write if we need datasync semantics, this is a pure
233 * data IO that doesn't require any metadata updates (including
234 * after IO completion such as unwritten extent conversion) and
235 * the underlying device supports FUA. This allows us to avoid
236 * cache flushes on IO completion.
237 */
238 if (!(iomap->flags & (IOMAP_F_SHARED|IOMAP_F_DIRTY)) &&
239 (dio->flags & IOMAP_DIO_WRITE_FUA) &&
240 blk_queue_fua(bdev_get_queue(iomap->bdev)))
241 use_fua = true;
242 }
243
244 /*
245 * Save the original count and trim the iter to just the extent we
246 * are operating on right now. The iter will be re-expanded once
247 * we are done.
248 */
249 orig_count = iov_iter_count(dio->submit.iter);
250 iov_iter_truncate(dio->submit.iter, length);
251
252 nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES);
253 if (nr_pages <= 0) {
254 ret = nr_pages;
255 goto out;
256 }
257
258 if (need_zeroout) {
259 /* zero out from the start of the block to the write offset */
260 pad = pos & (fs_block_size - 1);
261 if (pad)
262 iomap_dio_zero(dio, iomap, pos - pad, pad);
263 }
264
265 do {
266 size_t n;
267 if (dio->error) {
268 iov_iter_revert(dio->submit.iter, copied);
269 copied = ret = 0;
270 goto out;
271 }
272
273 bio = bio_alloc(GFP_KERNEL, nr_pages);
274 bio_set_dev(bio, iomap->bdev);
275 bio->bi_iter.bi_sector = iomap_sector(iomap, pos);
276 bio->bi_write_hint = dio->iocb->ki_hint;
277 bio->bi_ioprio = dio->iocb->ki_ioprio;
278 bio->bi_private = dio;
279 bio->bi_end_io = iomap_dio_bio_end_io;
280
281 ret = bio_iov_iter_get_pages(bio, dio->submit.iter);
282 if (unlikely(ret)) {
283 /*
284 * We have to stop part way through an IO. We must fall
285 * through to the sub-block tail zeroing here, otherwise
286 * this short IO may expose stale data in the tail of
287 * the block we haven't written data to.
288 */
289 bio_put(bio);
290 goto zero_tail;
291 }
292
293 n = bio->bi_iter.bi_size;
294 if (dio->flags & IOMAP_DIO_WRITE) {
295 bio->bi_opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
296 if (use_fua)
297 bio->bi_opf |= REQ_FUA;
298 else
299 dio->flags &= ~IOMAP_DIO_WRITE_FUA;
300 task_io_account_write(n);
301 } else {
302 bio->bi_opf = REQ_OP_READ;
303 if (dio->flags & IOMAP_DIO_DIRTY)
304 bio_set_pages_dirty(bio);
305 }
306
307 dio->size += n;
308 copied += n;
309
310 nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES);
311 iomap_dio_submit_bio(dio, iomap, bio, pos);
312 pos += n;
313 } while (nr_pages);
314
315 /*
316 * We need to zeroout the tail of a sub-block write if the extent type
317 * requires zeroing or the write extends beyond EOF. If we don't zero
318 * the block tail in the latter case, we can expose stale data via mmap
319 * reads of the EOF block.
320 */
321zero_tail:
322 if (need_zeroout ||
323 ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode))) {
324 /* zero out from the end of the write to the end of the block */
325 pad = pos & (fs_block_size - 1);
326 if (pad)
327 iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
328 }
329out:
330 /* Undo iter limitation to current extent */
331 iov_iter_reexpand(dio->submit.iter, orig_count - copied);
332 if (copied)
333 return copied;
334 return ret;
335}
336
337static loff_t
338iomap_dio_hole_actor(loff_t length, struct iomap_dio *dio)
339{
340 length = iov_iter_zero(length, dio->submit.iter);
341 dio->size += length;
342 return length;
343}
344
345static loff_t
346iomap_dio_inline_actor(struct inode *inode, loff_t pos, loff_t length,
347 struct iomap_dio *dio, struct iomap *iomap)
348{
349 struct iov_iter *iter = dio->submit.iter;
350 size_t copied;
351
352 BUG_ON(pos + length > PAGE_SIZE - offset_in_page(iomap->inline_data));
353
354 if (dio->flags & IOMAP_DIO_WRITE) {
355 loff_t size = inode->i_size;
356
357 if (pos > size)
358 memset(iomap->inline_data + size, 0, pos - size);
359 copied = copy_from_iter(iomap->inline_data + pos, length, iter);
360 if (copied) {
361 if (pos + copied > size)
362 i_size_write(inode, pos + copied);
363 mark_inode_dirty(inode);
364 }
365 } else {
366 copied = copy_to_iter(iomap->inline_data + pos, length, iter);
367 }
368 dio->size += copied;
369 return copied;
370}
371
372static loff_t
373iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
374 void *data, struct iomap *iomap, struct iomap *srcmap)
375{
376 struct iomap_dio *dio = data;
377
378 switch (iomap->type) {
379 case IOMAP_HOLE:
380 if (WARN_ON_ONCE(dio->flags & IOMAP_DIO_WRITE))
381 return -EIO;
382 return iomap_dio_hole_actor(length, dio);
383 case IOMAP_UNWRITTEN:
384 if (!(dio->flags & IOMAP_DIO_WRITE))
385 return iomap_dio_hole_actor(length, dio);
386 return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
387 case IOMAP_MAPPED:
388 return iomap_dio_bio_actor(inode, pos, length, dio, iomap);
389 case IOMAP_INLINE:
390 return iomap_dio_inline_actor(inode, pos, length, dio, iomap);
391 default:
392 WARN_ON_ONCE(1);
393 return -EIO;
394 }
395}
396
397/*
398 * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
399 * is being issued as AIO or not. This allows us to optimise pure data writes
400 * to use REQ_FUA rather than requiring generic_write_sync() to issue a
401 * REQ_FLUSH post write. This is slightly tricky because a single request here
402 * can be mapped into multiple disjoint IOs and only a subset of the IOs issued
403 * may be pure data writes. In that case, we still need to do a full data sync
404 * completion.
405 *
406 * Returns -ENOTBLK In case of a page invalidation invalidation failure for
407 * writes. The callers needs to fall back to buffered I/O in this case.
408 */
409ssize_t
410iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
411 const struct iomap_ops *ops, const struct iomap_dio_ops *dops,
412 bool wait_for_completion)
413{
414 struct address_space *mapping = iocb->ki_filp->f_mapping;
415 struct inode *inode = file_inode(iocb->ki_filp);
416 size_t count = iov_iter_count(iter);
417 loff_t pos = iocb->ki_pos;
418 loff_t end = iocb->ki_pos + count - 1, ret = 0;
419 unsigned int flags = IOMAP_DIRECT;
420 struct blk_plug plug;
421 struct iomap_dio *dio;
422
423 if (!count)
424 return 0;
425
426 if (WARN_ON(is_sync_kiocb(iocb) && !wait_for_completion))
427 return -EIO;
428
429 dio = kmalloc(sizeof(*dio), GFP_KERNEL);
430 if (!dio)
431 return -ENOMEM;
432
433 dio->iocb = iocb;
434 atomic_set(&dio->ref, 1);
435 dio->size = 0;
436 dio->i_size = i_size_read(inode);
437 dio->dops = dops;
438 dio->error = 0;
439 dio->flags = 0;
440
441 dio->submit.iter = iter;
442 dio->submit.waiter = current;
443 dio->submit.cookie = BLK_QC_T_NONE;
444 dio->submit.last_queue = NULL;
445
446 if (iov_iter_rw(iter) == READ) {
447 if (pos >= dio->i_size)
448 goto out_free_dio;
449
450 if (iter_is_iovec(iter))
451 dio->flags |= IOMAP_DIO_DIRTY;
452 } else {
453 flags |= IOMAP_WRITE;
454 dio->flags |= IOMAP_DIO_WRITE;
455
456 /* for data sync or sync, we need sync completion processing */
457 if (iocb->ki_flags & IOCB_DSYNC)
458 dio->flags |= IOMAP_DIO_NEED_SYNC;
459
460 /*
461 * For datasync only writes, we optimistically try using FUA for
462 * this IO. Any non-FUA write that occurs will clear this flag,
463 * hence we know before completion whether a cache flush is
464 * necessary.
465 */
466 if ((iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC)) == IOCB_DSYNC)
467 dio->flags |= IOMAP_DIO_WRITE_FUA;
468 }
469
470 if (iocb->ki_flags & IOCB_NOWAIT) {
471 if (filemap_range_has_page(mapping, pos, end)) {
472 ret = -EAGAIN;
473 goto out_free_dio;
474 }
475 flags |= IOMAP_NOWAIT;
476 }
477
478 ret = filemap_write_and_wait_range(mapping, pos, end);
479 if (ret)
480 goto out_free_dio;
481
482 if (iov_iter_rw(iter) == WRITE) {
483 /*
484 * Try to invalidate cache pages for the range we are writing.
485 * If this invalidation fails, let the caller fall back to
486 * buffered I/O.
487 */
488 if (invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT,
489 end >> PAGE_SHIFT)) {
490 trace_iomap_dio_invalidate_fail(inode, pos, count);
491 ret = -ENOTBLK;
492 goto out_free_dio;
493 }
494
495 if (!wait_for_completion && !inode->i_sb->s_dio_done_wq) {
496 ret = sb_init_dio_done_wq(inode->i_sb);
497 if (ret < 0)
498 goto out_free_dio;
499 }
500 }
501
502 inode_dio_begin(inode);
503
504 blk_start_plug(&plug);
505 do {
506 ret = iomap_apply(inode, pos, count, flags, ops, dio,
507 iomap_dio_actor);
508 if (ret <= 0) {
509 /* magic error code to fall back to buffered I/O */
510 if (ret == -ENOTBLK) {
511 wait_for_completion = true;
512 ret = 0;
513 }
514 break;
515 }
516 pos += ret;
517
518 if (iov_iter_rw(iter) == READ && pos >= dio->i_size) {
519 /*
520 * We only report that we've read data up to i_size.
521 * Revert iter to a state corresponding to that as
522 * some callers (such as splice code) rely on it.
523 */
524 iov_iter_revert(iter, pos - dio->i_size);
525 break;
526 }
527 } while ((count = iov_iter_count(iter)) > 0);
528 blk_finish_plug(&plug);
529
530 if (ret < 0)
531 iomap_dio_set_error(dio, ret);
532
533 /*
534 * If all the writes we issued were FUA, we don't need to flush the
535 * cache on IO completion. Clear the sync flag for this case.
536 */
537 if (dio->flags & IOMAP_DIO_WRITE_FUA)
538 dio->flags &= ~IOMAP_DIO_NEED_SYNC;
539
540 WRITE_ONCE(iocb->ki_cookie, dio->submit.cookie);
541 WRITE_ONCE(iocb->private, dio->submit.last_queue);
542
543 /*
544 * We are about to drop our additional submission reference, which
545 * might be the last reference to the dio. There are three different
546 * ways we can progress here:
547 *
548 * (a) If this is the last reference we will always complete and free
549 * the dio ourselves.
550 * (b) If this is not the last reference, and we serve an asynchronous
551 * iocb, we must never touch the dio after the decrement, the
552 * I/O completion handler will complete and free it.
553 * (c) If this is not the last reference, but we serve a synchronous
554 * iocb, the I/O completion handler will wake us up on the drop
555 * of the final reference, and we will complete and free it here
556 * after we got woken by the I/O completion handler.
557 */
558 dio->wait_for_completion = wait_for_completion;
559 if (!atomic_dec_and_test(&dio->ref)) {
560 if (!wait_for_completion)
561 return -EIOCBQUEUED;
562
563 for (;;) {
564 set_current_state(TASK_UNINTERRUPTIBLE);
565 if (!READ_ONCE(dio->submit.waiter))
566 break;
567
568 if (!(iocb->ki_flags & IOCB_HIPRI) ||
569 !dio->submit.last_queue ||
570 !blk_poll(dio->submit.last_queue,
571 dio->submit.cookie, true))
572 blk_io_schedule();
573 }
574 __set_current_state(TASK_RUNNING);
575 }
576
577 return iomap_dio_complete(dio);
578
579out_free_dio:
580 kfree(dio);
581 return ret;
582}
583EXPORT_SYMBOL_GPL(iomap_dio_rw);