xref: /linux/block/fops.c (revision f777d1112ee597d7f7dd3ca232220873a34ad0c8)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 1991, 1992  Linus Torvalds
4  * Copyright (C) 2001  Andrea Arcangeli <andrea@suse.de> SuSE
5  * Copyright (C) 2016 - 2020 Christoph Hellwig
6  */
7 #include <linux/init.h>
8 #include <linux/mm.h>
9 #include <linux/blkdev.h>
10 #include <linux/blk-integrity.h>
11 #include <linux/buffer_head.h>
12 #include <linux/mpage.h>
13 #include <linux/uio.h>
14 #include <linux/namei.h>
15 #include <linux/task_io_accounting_ops.h>
16 #include <linux/falloc.h>
17 #include <linux/suspend.h>
18 #include <linux/fs.h>
19 #include <linux/iomap.h>
20 #include <linux/module.h>
21 #include <linux/io_uring/cmd.h>
22 #include "blk.h"
23 
bdev_file_inode(struct file * file)24 static inline struct inode *bdev_file_inode(struct file *file)
25 {
26 	return file->f_mapping->host;
27 }
28 
dio_bio_write_op(struct kiocb * iocb)29 static blk_opf_t dio_bio_write_op(struct kiocb *iocb)
30 {
31 	blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
32 
33 	/* avoid the need for a I/O completion work item */
34 	if (iocb_is_dsync(iocb))
35 		opf |= REQ_FUA;
36 	return opf;
37 }
38 
blkdev_dio_invalid(struct block_device * bdev,struct kiocb * iocb,struct iov_iter * iter)39 static bool blkdev_dio_invalid(struct block_device *bdev, struct kiocb *iocb,
40 				struct iov_iter *iter)
41 {
42 	return iocb->ki_pos & (bdev_logical_block_size(bdev) - 1) ||
43 		!bdev_iter_is_aligned(bdev, iter);
44 }
45 
46 #define DIO_INLINE_BIO_VECS 4
47 
__blkdev_direct_IO_simple(struct kiocb * iocb,struct iov_iter * iter,struct block_device * bdev,unsigned int nr_pages)48 static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
49 		struct iov_iter *iter, struct block_device *bdev,
50 		unsigned int nr_pages)
51 {
52 	struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
53 	loff_t pos = iocb->ki_pos;
54 	bool should_dirty = false;
55 	struct bio bio;
56 	ssize_t ret;
57 
58 	if (nr_pages <= DIO_INLINE_BIO_VECS)
59 		vecs = inline_vecs;
60 	else {
61 		vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
62 				     GFP_KERNEL);
63 		if (!vecs)
64 			return -ENOMEM;
65 	}
66 
67 	if (iov_iter_rw(iter) == READ) {
68 		bio_init(&bio, bdev, vecs, nr_pages, REQ_OP_READ);
69 		if (user_backed_iter(iter))
70 			should_dirty = true;
71 	} else {
72 		bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb));
73 	}
74 	bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT;
75 	bio.bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
76 	bio.bi_write_stream = iocb->ki_write_stream;
77 	bio.bi_ioprio = iocb->ki_ioprio;
78 	if (iocb->ki_flags & IOCB_ATOMIC)
79 		bio.bi_opf |= REQ_ATOMIC;
80 
81 	ret = bio_iov_iter_get_pages(&bio, iter);
82 	if (unlikely(ret))
83 		goto out;
84 	ret = bio.bi_iter.bi_size;
85 
86 	if (iov_iter_rw(iter) == WRITE)
87 		task_io_account_write(ret);
88 
89 	if (iocb->ki_flags & IOCB_NOWAIT)
90 		bio.bi_opf |= REQ_NOWAIT;
91 
92 	submit_bio_wait(&bio);
93 
94 	bio_release_pages(&bio, should_dirty);
95 	if (unlikely(bio.bi_status))
96 		ret = blk_status_to_errno(bio.bi_status);
97 
98 out:
99 	if (vecs != inline_vecs)
100 		kfree(vecs);
101 
102 	bio_uninit(&bio);
103 
104 	return ret;
105 }
106 
107 enum {
108 	DIO_SHOULD_DIRTY	= 1,
109 	DIO_IS_SYNC		= 2,
110 };
111 
112 struct blkdev_dio {
113 	union {
114 		struct kiocb		*iocb;
115 		struct task_struct	*waiter;
116 	};
117 	size_t			size;
118 	atomic_t		ref;
119 	unsigned int		flags;
120 	struct bio		bio ____cacheline_aligned_in_smp;
121 };
122 
123 static struct bio_set blkdev_dio_pool;
124 
blkdev_bio_end_io(struct bio * bio)125 static void blkdev_bio_end_io(struct bio *bio)
126 {
127 	struct blkdev_dio *dio = bio->bi_private;
128 	bool should_dirty = dio->flags & DIO_SHOULD_DIRTY;
129 	bool is_sync = dio->flags & DIO_IS_SYNC;
130 
131 	if (bio->bi_status && !dio->bio.bi_status)
132 		dio->bio.bi_status = bio->bi_status;
133 
134 	if (bio_integrity(bio))
135 		bio_integrity_unmap_user(bio);
136 
137 	if (atomic_dec_and_test(&dio->ref)) {
138 		if (!is_sync) {
139 			struct kiocb *iocb = dio->iocb;
140 			ssize_t ret;
141 
142 			WRITE_ONCE(iocb->private, NULL);
143 
144 			if (likely(!dio->bio.bi_status)) {
145 				ret = dio->size;
146 				iocb->ki_pos += ret;
147 			} else {
148 				ret = blk_status_to_errno(dio->bio.bi_status);
149 			}
150 
151 			dio->iocb->ki_complete(iocb, ret);
152 			bio_put(&dio->bio);
153 		} else {
154 			struct task_struct *waiter = dio->waiter;
155 
156 			WRITE_ONCE(dio->waiter, NULL);
157 			blk_wake_io_task(waiter);
158 		}
159 	}
160 
161 	if (should_dirty) {
162 		bio_check_pages_dirty(bio);
163 	} else {
164 		bio_release_pages(bio, false);
165 		bio_put(bio);
166 	}
167 }
168 
__blkdev_direct_IO(struct kiocb * iocb,struct iov_iter * iter,struct block_device * bdev,unsigned int nr_pages)169 static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
170 		struct block_device *bdev, unsigned int nr_pages)
171 {
172 	struct blk_plug plug;
173 	struct blkdev_dio *dio;
174 	struct bio *bio;
175 	bool is_read = (iov_iter_rw(iter) == READ), is_sync;
176 	blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
177 	loff_t pos = iocb->ki_pos;
178 	int ret = 0;
179 
180 	if (iocb->ki_flags & IOCB_ALLOC_CACHE)
181 		opf |= REQ_ALLOC_CACHE;
182 	bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
183 			       &blkdev_dio_pool);
184 	dio = container_of(bio, struct blkdev_dio, bio);
185 	atomic_set(&dio->ref, 1);
186 	/*
187 	 * Grab an extra reference to ensure the dio structure which is embedded
188 	 * into the first bio stays around.
189 	 */
190 	bio_get(bio);
191 
192 	is_sync = is_sync_kiocb(iocb);
193 	if (is_sync) {
194 		dio->flags = DIO_IS_SYNC;
195 		dio->waiter = current;
196 	} else {
197 		dio->flags = 0;
198 		dio->iocb = iocb;
199 	}
200 
201 	dio->size = 0;
202 	if (is_read && user_backed_iter(iter))
203 		dio->flags |= DIO_SHOULD_DIRTY;
204 
205 	blk_start_plug(&plug);
206 
207 	for (;;) {
208 		bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
209 		bio->bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
210 		bio->bi_write_stream = iocb->ki_write_stream;
211 		bio->bi_private = dio;
212 		bio->bi_end_io = blkdev_bio_end_io;
213 		bio->bi_ioprio = iocb->ki_ioprio;
214 
215 		ret = bio_iov_iter_get_pages(bio, iter);
216 		if (unlikely(ret)) {
217 			bio->bi_status = BLK_STS_IOERR;
218 			bio_endio(bio);
219 			break;
220 		}
221 		if (iocb->ki_flags & IOCB_NOWAIT) {
222 			/*
223 			 * This is nonblocking IO, and we need to allocate
224 			 * another bio if we have data left to map. As we
225 			 * cannot guarantee that one of the sub bios will not
226 			 * fail getting issued FOR NOWAIT and as error results
227 			 * are coalesced across all of them, be safe and ask for
228 			 * a retry of this from blocking context.
229 			 */
230 			if (unlikely(iov_iter_count(iter))) {
231 				ret = -EAGAIN;
232 				goto fail;
233 			}
234 			bio->bi_opf |= REQ_NOWAIT;
235 		}
236 		if (iocb->ki_flags & IOCB_HAS_METADATA) {
237 			ret = bio_integrity_map_iter(bio, iocb->private);
238 			if (unlikely(ret))
239 				goto fail;
240 		}
241 
242 		if (is_read) {
243 			if (dio->flags & DIO_SHOULD_DIRTY)
244 				bio_set_pages_dirty(bio);
245 		} else {
246 			task_io_account_write(bio->bi_iter.bi_size);
247 		}
248 		dio->size += bio->bi_iter.bi_size;
249 		pos += bio->bi_iter.bi_size;
250 
251 		nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
252 		if (!nr_pages) {
253 			submit_bio(bio);
254 			break;
255 		}
256 		atomic_inc(&dio->ref);
257 		submit_bio(bio);
258 		bio = bio_alloc(bdev, nr_pages, opf, GFP_KERNEL);
259 	}
260 
261 	blk_finish_plug(&plug);
262 
263 	if (!is_sync)
264 		return -EIOCBQUEUED;
265 
266 	for (;;) {
267 		set_current_state(TASK_UNINTERRUPTIBLE);
268 		if (!READ_ONCE(dio->waiter))
269 			break;
270 		blk_io_schedule();
271 	}
272 	__set_current_state(TASK_RUNNING);
273 
274 	if (!ret)
275 		ret = blk_status_to_errno(dio->bio.bi_status);
276 	if (likely(!ret))
277 		ret = dio->size;
278 
279 	bio_put(&dio->bio);
280 	return ret;
281 fail:
282 	bio_release_pages(bio, false);
283 	bio_clear_flag(bio, BIO_REFFED);
284 	bio_put(bio);
285 	blk_finish_plug(&plug);
286 	return ret;
287 }
288 
blkdev_bio_end_io_async(struct bio * bio)289 static void blkdev_bio_end_io_async(struct bio *bio)
290 {
291 	struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio);
292 	struct kiocb *iocb = dio->iocb;
293 	ssize_t ret;
294 
295 	WRITE_ONCE(iocb->private, NULL);
296 
297 	if (likely(!bio->bi_status)) {
298 		ret = dio->size;
299 		iocb->ki_pos += ret;
300 	} else {
301 		ret = blk_status_to_errno(bio->bi_status);
302 	}
303 
304 	if (bio_integrity(bio))
305 		bio_integrity_unmap_user(bio);
306 
307 	iocb->ki_complete(iocb, ret);
308 
309 	if (dio->flags & DIO_SHOULD_DIRTY) {
310 		bio_check_pages_dirty(bio);
311 	} else {
312 		bio_release_pages(bio, false);
313 		bio_put(bio);
314 	}
315 }
316 
__blkdev_direct_IO_async(struct kiocb * iocb,struct iov_iter * iter,struct block_device * bdev,unsigned int nr_pages)317 static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
318 					struct iov_iter *iter,
319 					struct block_device *bdev,
320 					unsigned int nr_pages)
321 {
322 	bool is_read = iov_iter_rw(iter) == READ;
323 	blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
324 	struct blkdev_dio *dio;
325 	struct bio *bio;
326 	loff_t pos = iocb->ki_pos;
327 	int ret = 0;
328 
329 	if (iocb->ki_flags & IOCB_ALLOC_CACHE)
330 		opf |= REQ_ALLOC_CACHE;
331 	bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
332 			       &blkdev_dio_pool);
333 	dio = container_of(bio, struct blkdev_dio, bio);
334 	dio->flags = 0;
335 	dio->iocb = iocb;
336 	bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
337 	bio->bi_write_hint = file_inode(iocb->ki_filp)->i_write_hint;
338 	bio->bi_write_stream = iocb->ki_write_stream;
339 	bio->bi_end_io = blkdev_bio_end_io_async;
340 	bio->bi_ioprio = iocb->ki_ioprio;
341 
342 	if (iov_iter_is_bvec(iter)) {
343 		/*
344 		 * Users don't rely on the iterator being in any particular
345 		 * state for async I/O returning -EIOCBQUEUED, hence we can
346 		 * avoid expensive iov_iter_advance(). Bypass
347 		 * bio_iov_iter_get_pages() and set the bvec directly.
348 		 */
349 		bio_iov_bvec_set(bio, iter);
350 	} else {
351 		ret = bio_iov_iter_get_pages(bio, iter);
352 		if (unlikely(ret))
353 			goto out_bio_put;
354 	}
355 	dio->size = bio->bi_iter.bi_size;
356 
357 	if (is_read) {
358 		if (user_backed_iter(iter)) {
359 			dio->flags |= DIO_SHOULD_DIRTY;
360 			bio_set_pages_dirty(bio);
361 		}
362 	} else {
363 		task_io_account_write(bio->bi_iter.bi_size);
364 	}
365 
366 	if (iocb->ki_flags & IOCB_HAS_METADATA) {
367 		ret = bio_integrity_map_iter(bio, iocb->private);
368 		WRITE_ONCE(iocb->private, NULL);
369 		if (unlikely(ret))
370 			goto out_bio_put;
371 	}
372 
373 	if (iocb->ki_flags & IOCB_ATOMIC)
374 		bio->bi_opf |= REQ_ATOMIC;
375 
376 	if (iocb->ki_flags & IOCB_NOWAIT)
377 		bio->bi_opf |= REQ_NOWAIT;
378 
379 	if (iocb->ki_flags & IOCB_HIPRI) {
380 		bio->bi_opf |= REQ_POLLED;
381 		submit_bio(bio);
382 		WRITE_ONCE(iocb->private, bio);
383 	} else {
384 		submit_bio(bio);
385 	}
386 	return -EIOCBQUEUED;
387 
388 out_bio_put:
389 	bio_put(bio);
390 	return ret;
391 }
392 
blkdev_direct_IO(struct kiocb * iocb,struct iov_iter * iter)393 static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
394 {
395 	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
396 	unsigned int nr_pages;
397 
398 	if (!iov_iter_count(iter))
399 		return 0;
400 
401 	if (blkdev_dio_invalid(bdev, iocb, iter))
402 		return -EINVAL;
403 
404 	if (iov_iter_rw(iter) == WRITE) {
405 		u16 max_write_streams = bdev_max_write_streams(bdev);
406 
407 		if (iocb->ki_write_stream) {
408 			if (iocb->ki_write_stream > max_write_streams)
409 				return -EINVAL;
410 		} else if (max_write_streams) {
411 			enum rw_hint write_hint =
412 				file_inode(iocb->ki_filp)->i_write_hint;
413 
414 			/*
415 			 * Just use the write hint as write stream for block
416 			 * device writes.  This assumes no file system is
417 			 * mounted that would use the streams differently.
418 			 */
419 			if (write_hint <= max_write_streams)
420 				iocb->ki_write_stream = write_hint;
421 		}
422 	}
423 
424 	nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
425 	if (likely(nr_pages <= BIO_MAX_VECS &&
426 		   !(iocb->ki_flags & IOCB_HAS_METADATA))) {
427 		if (is_sync_kiocb(iocb))
428 			return __blkdev_direct_IO_simple(iocb, iter, bdev,
429 							nr_pages);
430 		return __blkdev_direct_IO_async(iocb, iter, bdev, nr_pages);
431 	} else if (iocb->ki_flags & IOCB_ATOMIC) {
432 		return -EINVAL;
433 	}
434 	return __blkdev_direct_IO(iocb, iter, bdev, bio_max_segs(nr_pages));
435 }
436 
blkdev_iomap_begin(struct inode * inode,loff_t offset,loff_t length,unsigned int flags,struct iomap * iomap,struct iomap * srcmap)437 static int blkdev_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
438 		unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
439 {
440 	struct block_device *bdev = I_BDEV(inode);
441 	loff_t isize = i_size_read(inode);
442 
443 	if (offset >= isize)
444 		return -EIO;
445 
446 	iomap->bdev = bdev;
447 	iomap->offset = ALIGN_DOWN(offset, bdev_logical_block_size(bdev));
448 	iomap->type = IOMAP_MAPPED;
449 	iomap->addr = iomap->offset;
450 	iomap->length = isize - iomap->offset;
451 	iomap->flags |= IOMAP_F_BUFFER_HEAD; /* noop for !CONFIG_BUFFER_HEAD */
452 	return 0;
453 }
454 
455 static const struct iomap_ops blkdev_iomap_ops = {
456 	.iomap_begin		= blkdev_iomap_begin,
457 };
458 
459 #ifdef CONFIG_BUFFER_HEAD
blkdev_get_block(struct inode * inode,sector_t iblock,struct buffer_head * bh,int create)460 static int blkdev_get_block(struct inode *inode, sector_t iblock,
461 		struct buffer_head *bh, int create)
462 {
463 	bh->b_bdev = I_BDEV(inode);
464 	bh->b_blocknr = iblock;
465 	set_buffer_mapped(bh);
466 	return 0;
467 }
468 
469 /*
470  * We cannot call mpage_writepages() as it does not take the buffer lock.
471  * We must use block_write_full_folio() directly which holds the buffer
472  * lock.  The buffer lock provides the synchronisation with writeback
473  * that filesystems rely on when they use the blockdev's mapping.
474  */
blkdev_writepages(struct address_space * mapping,struct writeback_control * wbc)475 static int blkdev_writepages(struct address_space *mapping,
476 		struct writeback_control *wbc)
477 {
478 	struct folio *folio = NULL;
479 	struct blk_plug plug;
480 	int err;
481 
482 	blk_start_plug(&plug);
483 	while ((folio = writeback_iter(mapping, wbc, folio, &err)))
484 		err = block_write_full_folio(folio, wbc, blkdev_get_block);
485 	blk_finish_plug(&plug);
486 
487 	return err;
488 }
489 
blkdev_read_folio(struct file * file,struct folio * folio)490 static int blkdev_read_folio(struct file *file, struct folio *folio)
491 {
492 	return block_read_full_folio(folio, blkdev_get_block);
493 }
494 
blkdev_readahead(struct readahead_control * rac)495 static void blkdev_readahead(struct readahead_control *rac)
496 {
497 	mpage_readahead(rac, blkdev_get_block);
498 }
499 
blkdev_write_begin(const struct kiocb * iocb,struct address_space * mapping,loff_t pos,unsigned len,struct folio ** foliop,void ** fsdata)500 static int blkdev_write_begin(const struct kiocb *iocb,
501 			      struct address_space *mapping, loff_t pos,
502 			      unsigned len, struct folio **foliop,
503 			      void **fsdata)
504 {
505 	return block_write_begin(mapping, pos, len, foliop, blkdev_get_block);
506 }
507 
blkdev_write_end(const struct kiocb * iocb,struct address_space * mapping,loff_t pos,unsigned len,unsigned copied,struct folio * folio,void * fsdata)508 static int blkdev_write_end(const struct kiocb *iocb,
509 			    struct address_space *mapping,
510 			    loff_t pos, unsigned len, unsigned copied,
511 			    struct folio *folio, void *fsdata)
512 {
513 	int ret;
514 	ret = block_write_end(pos, len, copied, folio);
515 
516 	folio_unlock(folio);
517 	folio_put(folio);
518 
519 	return ret;
520 }
521 
522 const struct address_space_operations def_blk_aops = {
523 	.dirty_folio	= block_dirty_folio,
524 	.invalidate_folio = block_invalidate_folio,
525 	.read_folio	= blkdev_read_folio,
526 	.readahead	= blkdev_readahead,
527 	.writepages	= blkdev_writepages,
528 	.write_begin	= blkdev_write_begin,
529 	.write_end	= blkdev_write_end,
530 	.migrate_folio	= buffer_migrate_folio_norefs,
531 	.is_dirty_writeback = buffer_check_dirty_writeback,
532 };
533 #else /* CONFIG_BUFFER_HEAD */
blkdev_read_folio(struct file * file,struct folio * folio)534 static int blkdev_read_folio(struct file *file, struct folio *folio)
535 {
536 	return iomap_read_folio(folio, &blkdev_iomap_ops);
537 }
538 
blkdev_readahead(struct readahead_control * rac)539 static void blkdev_readahead(struct readahead_control *rac)
540 {
541 	iomap_readahead(rac, &blkdev_iomap_ops);
542 }
543 
blkdev_writeback_range(struct iomap_writepage_ctx * wpc,struct folio * folio,u64 offset,unsigned int len,u64 end_pos)544 static ssize_t blkdev_writeback_range(struct iomap_writepage_ctx *wpc,
545 		struct folio *folio, u64 offset, unsigned int len, u64 end_pos)
546 {
547 	loff_t isize = i_size_read(wpc->inode);
548 
549 	if (WARN_ON_ONCE(offset >= isize))
550 		return -EIO;
551 
552 	if (offset < wpc->iomap.offset ||
553 	    offset >= wpc->iomap.offset + wpc->iomap.length) {
554 		int error;
555 
556 		error = blkdev_iomap_begin(wpc->inode, offset, isize - offset,
557 				IOMAP_WRITE, &wpc->iomap, NULL);
558 		if (error)
559 			return error;
560 	}
561 
562 	return iomap_add_to_ioend(wpc, folio, offset, end_pos, len);
563 }
564 
565 static const struct iomap_writeback_ops blkdev_writeback_ops = {
566 	.writeback_range	= blkdev_writeback_range,
567 	.writeback_submit	= iomap_ioend_writeback_submit,
568 };
569 
blkdev_writepages(struct address_space * mapping,struct writeback_control * wbc)570 static int blkdev_writepages(struct address_space *mapping,
571 		struct writeback_control *wbc)
572 {
573 	struct iomap_writepage_ctx wpc = {
574 		.inode		= mapping->host,
575 		.wbc		= wbc,
576 		.ops		= &blkdev_writeback_ops
577 	};
578 
579 	return iomap_writepages(&wpc);
580 }
581 
582 const struct address_space_operations def_blk_aops = {
583 	.dirty_folio	= filemap_dirty_folio,
584 	.release_folio		= iomap_release_folio,
585 	.invalidate_folio	= iomap_invalidate_folio,
586 	.read_folio		= blkdev_read_folio,
587 	.readahead		= blkdev_readahead,
588 	.writepages		= blkdev_writepages,
589 	.is_partially_uptodate  = iomap_is_partially_uptodate,
590 	.error_remove_folio	= generic_error_remove_folio,
591 	.migrate_folio		= filemap_migrate_folio,
592 };
593 #endif /* CONFIG_BUFFER_HEAD */
594 
595 /*
596  * for a block special file file_inode(file)->i_size is zero
597  * so we compute the size by hand (just as in block_read/write above)
598  */
blkdev_llseek(struct file * file,loff_t offset,int whence)599 static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
600 {
601 	struct inode *bd_inode = bdev_file_inode(file);
602 	loff_t retval;
603 
604 	inode_lock(bd_inode);
605 	retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
606 	inode_unlock(bd_inode);
607 	return retval;
608 }
609 
blkdev_fsync(struct file * filp,loff_t start,loff_t end,int datasync)610 static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
611 		int datasync)
612 {
613 	struct block_device *bdev = I_BDEV(filp->f_mapping->host);
614 	int error;
615 
616 	error = file_write_and_wait_range(filp, start, end);
617 	if (error)
618 		return error;
619 
620 	/*
621 	 * There is no need to serialise calls to blkdev_issue_flush with
622 	 * i_mutex and doing so causes performance issues with concurrent
623 	 * O_SYNC writers to a block device.
624 	 */
625 	error = blkdev_issue_flush(bdev);
626 	if (error == -EOPNOTSUPP)
627 		error = 0;
628 
629 	return error;
630 }
631 
632 /**
633  * file_to_blk_mode - get block open flags from file flags
634  * @file: file whose open flags should be converted
635  *
636  * Look at file open flags and generate corresponding block open flags from
637  * them. The function works both for file just being open (e.g. during ->open
638  * callback) and for file that is already open. This is actually non-trivial
639  * (see comment in the function).
640  */
file_to_blk_mode(struct file * file)641 blk_mode_t file_to_blk_mode(struct file *file)
642 {
643 	blk_mode_t mode = 0;
644 
645 	if (file->f_mode & FMODE_READ)
646 		mode |= BLK_OPEN_READ;
647 	if (file->f_mode & FMODE_WRITE)
648 		mode |= BLK_OPEN_WRITE;
649 	/*
650 	 * do_dentry_open() clears O_EXCL from f_flags, use file->private_data
651 	 * to determine whether the open was exclusive for already open files.
652 	 */
653 	if (file->private_data)
654 		mode |= BLK_OPEN_EXCL;
655 	else if (file->f_flags & O_EXCL)
656 		mode |= BLK_OPEN_EXCL;
657 	if (file->f_flags & O_NDELAY)
658 		mode |= BLK_OPEN_NDELAY;
659 
660 	/*
661 	 * If all bits in O_ACCMODE set (aka O_RDWR | O_WRONLY), the floppy
662 	 * driver has historically allowed ioctls as if the file was opened for
663 	 * writing, but does not allow and actual reads or writes.
664 	 */
665 	if ((file->f_flags & O_ACCMODE) == (O_RDWR | O_WRONLY))
666 		mode |= BLK_OPEN_WRITE_IOCTL;
667 
668 	return mode;
669 }
670 
blkdev_open(struct inode * inode,struct file * filp)671 static int blkdev_open(struct inode *inode, struct file *filp)
672 {
673 	struct block_device *bdev;
674 	blk_mode_t mode;
675 	int ret;
676 
677 	mode = file_to_blk_mode(filp);
678 	/* Use the file as the holder. */
679 	if (mode & BLK_OPEN_EXCL)
680 		filp->private_data = filp;
681 	ret = bdev_permission(inode->i_rdev, mode, filp->private_data);
682 	if (ret)
683 		return ret;
684 
685 	bdev = blkdev_get_no_open(inode->i_rdev, true);
686 	if (!bdev)
687 		return -ENXIO;
688 
689 	if (bdev_can_atomic_write(bdev))
690 		filp->f_mode |= FMODE_CAN_ATOMIC_WRITE;
691 	if (blk_get_integrity(bdev->bd_disk))
692 		filp->f_mode |= FMODE_HAS_METADATA;
693 
694 	ret = bdev_open(bdev, mode, filp->private_data, NULL, filp);
695 	if (ret)
696 		blkdev_put_no_open(bdev);
697 	return ret;
698 }
699 
blkdev_release(struct inode * inode,struct file * filp)700 static int blkdev_release(struct inode *inode, struct file *filp)
701 {
702 	bdev_release(filp);
703 	return 0;
704 }
705 
706 static ssize_t
blkdev_direct_write(struct kiocb * iocb,struct iov_iter * from)707 blkdev_direct_write(struct kiocb *iocb, struct iov_iter *from)
708 {
709 	size_t count = iov_iter_count(from);
710 	ssize_t written;
711 
712 	written = kiocb_invalidate_pages(iocb, count);
713 	if (written) {
714 		if (written == -EBUSY)
715 			return 0;
716 		return written;
717 	}
718 
719 	written = blkdev_direct_IO(iocb, from);
720 	if (written > 0) {
721 		kiocb_invalidate_post_direct_write(iocb, count);
722 		iocb->ki_pos += written;
723 		count -= written;
724 	}
725 	if (written != -EIOCBQUEUED)
726 		iov_iter_revert(from, count - iov_iter_count(from));
727 	return written;
728 }
729 
blkdev_buffered_write(struct kiocb * iocb,struct iov_iter * from)730 static ssize_t blkdev_buffered_write(struct kiocb *iocb, struct iov_iter *from)
731 {
732 	return iomap_file_buffered_write(iocb, from, &blkdev_iomap_ops, NULL,
733 			NULL);
734 }
735 
736 /*
737  * Write data to the block device.  Only intended for the block device itself
738  * and the raw driver which basically is a fake block device.
739  *
740  * Does not take i_mutex for the write and thus is not for general purpose
741  * use.
742  */
blkdev_write_iter(struct kiocb * iocb,struct iov_iter * from)743 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
744 {
745 	struct file *file = iocb->ki_filp;
746 	struct inode *bd_inode = bdev_file_inode(file);
747 	struct block_device *bdev = I_BDEV(bd_inode);
748 	bool atomic = iocb->ki_flags & IOCB_ATOMIC;
749 	loff_t size = bdev_nr_bytes(bdev);
750 	size_t shorted = 0;
751 	ssize_t ret;
752 
753 	if (bdev_read_only(bdev))
754 		return -EPERM;
755 
756 	if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
757 		return -ETXTBSY;
758 
759 	if (!iov_iter_count(from))
760 		return 0;
761 
762 	if (iocb->ki_pos >= size)
763 		return -ENOSPC;
764 
765 	if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
766 		return -EOPNOTSUPP;
767 
768 	if (atomic) {
769 		ret = generic_atomic_write_valid(iocb, from);
770 		if (ret)
771 			return ret;
772 	}
773 
774 	size -= iocb->ki_pos;
775 	if (iov_iter_count(from) > size) {
776 		if (atomic)
777 			return -EINVAL;
778 		shorted = iov_iter_count(from) - size;
779 		iov_iter_truncate(from, size);
780 	}
781 
782 	ret = file_update_time(file);
783 	if (ret)
784 		return ret;
785 
786 	if (iocb->ki_flags & IOCB_DIRECT) {
787 		ret = blkdev_direct_write(iocb, from);
788 		if (ret >= 0 && iov_iter_count(from))
789 			ret = direct_write_fallback(iocb, from, ret,
790 					blkdev_buffered_write(iocb, from));
791 	} else {
792 		/*
793 		 * Take i_rwsem and invalidate_lock to avoid racing with
794 		 * set_blocksize changing i_blkbits/folio order and punching
795 		 * out the pagecache.
796 		 */
797 		inode_lock_shared(bd_inode);
798 		ret = blkdev_buffered_write(iocb, from);
799 		inode_unlock_shared(bd_inode);
800 	}
801 
802 	if (ret > 0)
803 		ret = generic_write_sync(iocb, ret);
804 	iov_iter_reexpand(from, iov_iter_count(from) + shorted);
805 	return ret;
806 }
807 
blkdev_read_iter(struct kiocb * iocb,struct iov_iter * to)808 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
809 {
810 	struct inode *bd_inode = bdev_file_inode(iocb->ki_filp);
811 	struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
812 	loff_t size = bdev_nr_bytes(bdev);
813 	loff_t pos = iocb->ki_pos;
814 	size_t shorted = 0;
815 	ssize_t ret = 0;
816 	size_t count;
817 
818 	if (unlikely(pos + iov_iter_count(to) > size)) {
819 		if (pos >= size)
820 			return 0;
821 		size -= pos;
822 		shorted = iov_iter_count(to) - size;
823 		iov_iter_truncate(to, size);
824 	}
825 
826 	count = iov_iter_count(to);
827 	if (!count)
828 		goto reexpand; /* skip atime */
829 
830 	if (iocb->ki_flags & IOCB_DIRECT) {
831 		ret = kiocb_write_and_wait(iocb, count);
832 		if (ret < 0)
833 			goto reexpand;
834 		file_accessed(iocb->ki_filp);
835 
836 		ret = blkdev_direct_IO(iocb, to);
837 		if (ret > 0) {
838 			iocb->ki_pos += ret;
839 			count -= ret;
840 		}
841 		if (ret != -EIOCBQUEUED)
842 			iov_iter_revert(to, count - iov_iter_count(to));
843 		if (ret < 0 || !count)
844 			goto reexpand;
845 	}
846 
847 	/*
848 	 * Take i_rwsem and invalidate_lock to avoid racing with set_blocksize
849 	 * changing i_blkbits/folio order and punching out the pagecache.
850 	 */
851 	inode_lock_shared(bd_inode);
852 	ret = filemap_read(iocb, to, ret);
853 	inode_unlock_shared(bd_inode);
854 
855 reexpand:
856 	if (unlikely(shorted))
857 		iov_iter_reexpand(to, iov_iter_count(to) + shorted);
858 	return ret;
859 }
860 
861 #define	BLKDEV_FALLOC_FL_SUPPORTED					\
862 		(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |		\
863 		 FALLOC_FL_ZERO_RANGE | FALLOC_FL_WRITE_ZEROES)
864 
blkdev_fallocate(struct file * file,int mode,loff_t start,loff_t len)865 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
866 			     loff_t len)
867 {
868 	struct inode *inode = bdev_file_inode(file);
869 	struct block_device *bdev = I_BDEV(inode);
870 	loff_t end = start + len - 1;
871 	loff_t isize;
872 	unsigned int flags;
873 	int error;
874 
875 	/* Fail if we don't recognize the flags. */
876 	if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
877 		return -EOPNOTSUPP;
878 	/*
879 	 * Don't allow writing zeroes if the device does not enable the
880 	 * unmap write zeroes operation.
881 	 */
882 	if ((mode & FALLOC_FL_WRITE_ZEROES) &&
883 	    !bdev_write_zeroes_unmap_sectors(bdev))
884 		return -EOPNOTSUPP;
885 
886 	/* Don't go off the end of the device. */
887 	isize = bdev_nr_bytes(bdev);
888 	if (start >= isize)
889 		return -EINVAL;
890 	if (end >= isize) {
891 		if (mode & FALLOC_FL_KEEP_SIZE) {
892 			len = isize - start;
893 			end = start + len - 1;
894 		} else
895 			return -EINVAL;
896 	}
897 
898 	/*
899 	 * Don't allow IO that isn't aligned to logical block size.
900 	 */
901 	if ((start | len) & (bdev_logical_block_size(bdev) - 1))
902 		return -EINVAL;
903 
904 	inode_lock(inode);
905 	filemap_invalidate_lock(inode->i_mapping);
906 
907 	switch (mode) {
908 	case FALLOC_FL_ZERO_RANGE:
909 	case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
910 		flags = BLKDEV_ZERO_NOUNMAP;
911 		break;
912 	case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
913 		flags = BLKDEV_ZERO_NOFALLBACK;
914 		break;
915 	case FALLOC_FL_WRITE_ZEROES:
916 		flags = 0;
917 		break;
918 	default:
919 		error = -EOPNOTSUPP;
920 		goto fail;
921 	}
922 
923 	/*
924 	 * Invalidate the page cache, including dirty pages, for valid
925 	 * de-allocate mode calls to fallocate().
926 	 */
927 	error = truncate_bdev_range(bdev, file_to_blk_mode(file), start, end);
928 	if (error)
929 		goto fail;
930 
931 	error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
932 				     len >> SECTOR_SHIFT, GFP_KERNEL, flags);
933  fail:
934 	filemap_invalidate_unlock(inode->i_mapping);
935 	inode_unlock(inode);
936 	return error;
937 }
938 
blkdev_mmap_prepare(struct vm_area_desc * desc)939 static int blkdev_mmap_prepare(struct vm_area_desc *desc)
940 {
941 	struct file *file = desc->file;
942 
943 	if (bdev_read_only(I_BDEV(bdev_file_inode(file))))
944 		return generic_file_readonly_mmap_prepare(desc);
945 
946 	return generic_file_mmap_prepare(desc);
947 }
948 
949 const struct file_operations def_blk_fops = {
950 	.open		= blkdev_open,
951 	.release	= blkdev_release,
952 	.llseek		= blkdev_llseek,
953 	.read_iter	= blkdev_read_iter,
954 	.write_iter	= blkdev_write_iter,
955 	.iopoll		= iocb_bio_iopoll,
956 	.mmap_prepare	= blkdev_mmap_prepare,
957 	.fsync		= blkdev_fsync,
958 	.unlocked_ioctl	= blkdev_ioctl,
959 #ifdef CONFIG_COMPAT
960 	.compat_ioctl	= compat_blkdev_ioctl,
961 #endif
962 	.splice_read	= filemap_splice_read,
963 	.splice_write	= iter_file_splice_write,
964 	.fallocate	= blkdev_fallocate,
965 	.uring_cmd	= blkdev_uring_cmd,
966 	.fop_flags	= FOP_BUFFER_RASYNC,
967 };
968 
blkdev_init(void)969 static __init int blkdev_init(void)
970 {
971 	return bioset_init(&blkdev_dio_pool, 4,
972 				offsetof(struct blkdev_dio, bio),
973 				BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
974 }
975 module_init(blkdev_init);
976