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