Merge tag '6.6-rc5-ksmbd-server-fixes' of git://git.samba.org/ksmbd
[platform/kernel/linux-rpi.git] / block / fops.c
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/buffer_head.h>
11 #include <linux/mpage.h>
12 #include <linux/uio.h>
13 #include <linux/namei.h>
14 #include <linux/task_io_accounting_ops.h>
15 #include <linux/falloc.h>
16 #include <linux/suspend.h>
17 #include <linux/fs.h>
18 #include <linux/iomap.h>
19 #include <linux/module.h>
20 #include "blk.h"
21
22 static inline struct inode *bdev_file_inode(struct file *file)
23 {
24         return file->f_mapping->host;
25 }
26
27 static blk_opf_t dio_bio_write_op(struct kiocb *iocb)
28 {
29         blk_opf_t opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
30
31         /* avoid the need for a I/O completion work item */
32         if (iocb_is_dsync(iocb))
33                 opf |= REQ_FUA;
34         return opf;
35 }
36
37 static bool blkdev_dio_unaligned(struct block_device *bdev, loff_t pos,
38                               struct iov_iter *iter)
39 {
40         return pos & (bdev_logical_block_size(bdev) - 1) ||
41                 !bdev_iter_is_aligned(bdev, iter);
42 }
43
44 #define DIO_INLINE_BIO_VECS 4
45
46 static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
47                 struct iov_iter *iter, unsigned int nr_pages)
48 {
49         struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
50         struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
51         loff_t pos = iocb->ki_pos;
52         bool should_dirty = false;
53         struct bio bio;
54         ssize_t ret;
55
56         if (blkdev_dio_unaligned(bdev, pos, iter))
57                 return -EINVAL;
58
59         if (nr_pages <= DIO_INLINE_BIO_VECS)
60                 vecs = inline_vecs;
61         else {
62                 vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
63                                      GFP_KERNEL);
64                 if (!vecs)
65                         return -ENOMEM;
66         }
67
68         if (iov_iter_rw(iter) == READ) {
69                 bio_init(&bio, bdev, vecs, nr_pages, REQ_OP_READ);
70                 if (user_backed_iter(iter))
71                         should_dirty = true;
72         } else {
73                 bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb));
74         }
75         bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT;
76         bio.bi_ioprio = iocb->ki_ioprio;
77
78         ret = bio_iov_iter_get_pages(&bio, iter);
79         if (unlikely(ret))
80                 goto out;
81         ret = bio.bi_iter.bi_size;
82
83         if (iov_iter_rw(iter) == WRITE)
84                 task_io_account_write(ret);
85
86         if (iocb->ki_flags & IOCB_NOWAIT)
87                 bio.bi_opf |= REQ_NOWAIT;
88
89         submit_bio_wait(&bio);
90
91         bio_release_pages(&bio, should_dirty);
92         if (unlikely(bio.bi_status))
93                 ret = blk_status_to_errno(bio.bi_status);
94
95 out:
96         if (vecs != inline_vecs)
97                 kfree(vecs);
98
99         bio_uninit(&bio);
100
101         return ret;
102 }
103
104 enum {
105         DIO_SHOULD_DIRTY        = 1,
106         DIO_IS_SYNC             = 2,
107 };
108
109 struct blkdev_dio {
110         union {
111                 struct kiocb            *iocb;
112                 struct task_struct      *waiter;
113         };
114         size_t                  size;
115         atomic_t                ref;
116         unsigned int            flags;
117         struct bio              bio ____cacheline_aligned_in_smp;
118 };
119
120 static struct bio_set blkdev_dio_pool;
121
122 static void blkdev_bio_end_io(struct bio *bio)
123 {
124         struct blkdev_dio *dio = bio->bi_private;
125         bool should_dirty = dio->flags & DIO_SHOULD_DIRTY;
126
127         if (bio->bi_status && !dio->bio.bi_status)
128                 dio->bio.bi_status = bio->bi_status;
129
130         if (atomic_dec_and_test(&dio->ref)) {
131                 if (!(dio->flags & DIO_IS_SYNC)) {
132                         struct kiocb *iocb = dio->iocb;
133                         ssize_t ret;
134
135                         WRITE_ONCE(iocb->private, NULL);
136
137                         if (likely(!dio->bio.bi_status)) {
138                                 ret = dio->size;
139                                 iocb->ki_pos += ret;
140                         } else {
141                                 ret = blk_status_to_errno(dio->bio.bi_status);
142                         }
143
144                         dio->iocb->ki_complete(iocb, ret);
145                         bio_put(&dio->bio);
146                 } else {
147                         struct task_struct *waiter = dio->waiter;
148
149                         WRITE_ONCE(dio->waiter, NULL);
150                         blk_wake_io_task(waiter);
151                 }
152         }
153
154         if (should_dirty) {
155                 bio_check_pages_dirty(bio);
156         } else {
157                 bio_release_pages(bio, false);
158                 bio_put(bio);
159         }
160 }
161
162 static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
163                 unsigned int nr_pages)
164 {
165         struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
166         struct blk_plug plug;
167         struct blkdev_dio *dio;
168         struct bio *bio;
169         bool is_read = (iov_iter_rw(iter) == READ), is_sync;
170         blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
171         loff_t pos = iocb->ki_pos;
172         int ret = 0;
173
174         if (blkdev_dio_unaligned(bdev, pos, iter))
175                 return -EINVAL;
176
177         if (iocb->ki_flags & IOCB_ALLOC_CACHE)
178                 opf |= REQ_ALLOC_CACHE;
179         bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
180                                &blkdev_dio_pool);
181         dio = container_of(bio, struct blkdev_dio, bio);
182         atomic_set(&dio->ref, 1);
183         /*
184          * Grab an extra reference to ensure the dio structure which is embedded
185          * into the first bio stays around.
186          */
187         bio_get(bio);
188
189         is_sync = is_sync_kiocb(iocb);
190         if (is_sync) {
191                 dio->flags = DIO_IS_SYNC;
192                 dio->waiter = current;
193         } else {
194                 dio->flags = 0;
195                 dio->iocb = iocb;
196         }
197
198         dio->size = 0;
199         if (is_read && user_backed_iter(iter))
200                 dio->flags |= DIO_SHOULD_DIRTY;
201
202         blk_start_plug(&plug);
203
204         for (;;) {
205                 bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
206                 bio->bi_private = dio;
207                 bio->bi_end_io = blkdev_bio_end_io;
208                 bio->bi_ioprio = iocb->ki_ioprio;
209
210                 ret = bio_iov_iter_get_pages(bio, iter);
211                 if (unlikely(ret)) {
212                         bio->bi_status = BLK_STS_IOERR;
213                         bio_endio(bio);
214                         break;
215                 }
216                 if (iocb->ki_flags & IOCB_NOWAIT) {
217                         /*
218                          * This is nonblocking IO, and we need to allocate
219                          * another bio if we have data left to map. As we
220                          * cannot guarantee that one of the sub bios will not
221                          * fail getting issued FOR NOWAIT and as error results
222                          * are coalesced across all of them, be safe and ask for
223                          * a retry of this from blocking context.
224                          */
225                         if (unlikely(iov_iter_count(iter))) {
226                                 bio_release_pages(bio, false);
227                                 bio_clear_flag(bio, BIO_REFFED);
228                                 bio_put(bio);
229                                 blk_finish_plug(&plug);
230                                 return -EAGAIN;
231                         }
232                         bio->bi_opf |= REQ_NOWAIT;
233                 }
234
235                 if (is_read) {
236                         if (dio->flags & DIO_SHOULD_DIRTY)
237                                 bio_set_pages_dirty(bio);
238                 } else {
239                         task_io_account_write(bio->bi_iter.bi_size);
240                 }
241                 dio->size += bio->bi_iter.bi_size;
242                 pos += bio->bi_iter.bi_size;
243
244                 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
245                 if (!nr_pages) {
246                         submit_bio(bio);
247                         break;
248                 }
249                 atomic_inc(&dio->ref);
250                 submit_bio(bio);
251                 bio = bio_alloc(bdev, nr_pages, opf, GFP_KERNEL);
252         }
253
254         blk_finish_plug(&plug);
255
256         if (!is_sync)
257                 return -EIOCBQUEUED;
258
259         for (;;) {
260                 set_current_state(TASK_UNINTERRUPTIBLE);
261                 if (!READ_ONCE(dio->waiter))
262                         break;
263                 blk_io_schedule();
264         }
265         __set_current_state(TASK_RUNNING);
266
267         if (!ret)
268                 ret = blk_status_to_errno(dio->bio.bi_status);
269         if (likely(!ret))
270                 ret = dio->size;
271
272         bio_put(&dio->bio);
273         return ret;
274 }
275
276 static void blkdev_bio_end_io_async(struct bio *bio)
277 {
278         struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio);
279         struct kiocb *iocb = dio->iocb;
280         ssize_t ret;
281
282         WRITE_ONCE(iocb->private, NULL);
283
284         if (likely(!bio->bi_status)) {
285                 ret = dio->size;
286                 iocb->ki_pos += ret;
287         } else {
288                 ret = blk_status_to_errno(bio->bi_status);
289         }
290
291         iocb->ki_complete(iocb, ret);
292
293         if (dio->flags & DIO_SHOULD_DIRTY) {
294                 bio_check_pages_dirty(bio);
295         } else {
296                 bio_release_pages(bio, false);
297                 bio_put(bio);
298         }
299 }
300
301 static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
302                                         struct iov_iter *iter,
303                                         unsigned int nr_pages)
304 {
305         struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
306         bool is_read = iov_iter_rw(iter) == READ;
307         blk_opf_t opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
308         struct blkdev_dio *dio;
309         struct bio *bio;
310         loff_t pos = iocb->ki_pos;
311         int ret = 0;
312
313         if (blkdev_dio_unaligned(bdev, pos, iter))
314                 return -EINVAL;
315
316         if (iocb->ki_flags & IOCB_ALLOC_CACHE)
317                 opf |= REQ_ALLOC_CACHE;
318         bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
319                                &blkdev_dio_pool);
320         dio = container_of(bio, struct blkdev_dio, bio);
321         dio->flags = 0;
322         dio->iocb = iocb;
323         bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
324         bio->bi_end_io = blkdev_bio_end_io_async;
325         bio->bi_ioprio = iocb->ki_ioprio;
326
327         if (iov_iter_is_bvec(iter)) {
328                 /*
329                  * Users don't rely on the iterator being in any particular
330                  * state for async I/O returning -EIOCBQUEUED, hence we can
331                  * avoid expensive iov_iter_advance(). Bypass
332                  * bio_iov_iter_get_pages() and set the bvec directly.
333                  */
334                 bio_iov_bvec_set(bio, iter);
335         } else {
336                 ret = bio_iov_iter_get_pages(bio, iter);
337                 if (unlikely(ret)) {
338                         bio_put(bio);
339                         return ret;
340                 }
341         }
342         dio->size = bio->bi_iter.bi_size;
343
344         if (is_read) {
345                 if (user_backed_iter(iter)) {
346                         dio->flags |= DIO_SHOULD_DIRTY;
347                         bio_set_pages_dirty(bio);
348                 }
349         } else {
350                 task_io_account_write(bio->bi_iter.bi_size);
351         }
352
353         if (iocb->ki_flags & IOCB_NOWAIT)
354                 bio->bi_opf |= REQ_NOWAIT;
355
356         if (iocb->ki_flags & IOCB_HIPRI) {
357                 bio->bi_opf |= REQ_POLLED;
358                 submit_bio(bio);
359                 WRITE_ONCE(iocb->private, bio);
360         } else {
361                 submit_bio(bio);
362         }
363         return -EIOCBQUEUED;
364 }
365
366 static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
367 {
368         unsigned int nr_pages;
369
370         if (!iov_iter_count(iter))
371                 return 0;
372
373         nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
374         if (likely(nr_pages <= BIO_MAX_VECS)) {
375                 if (is_sync_kiocb(iocb))
376                         return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
377                 return __blkdev_direct_IO_async(iocb, iter, nr_pages);
378         }
379         return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
380 }
381
382 static int blkdev_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
383                 unsigned int flags, struct iomap *iomap, struct iomap *srcmap)
384 {
385         struct block_device *bdev = I_BDEV(inode);
386         loff_t isize = i_size_read(inode);
387
388         iomap->bdev = bdev;
389         iomap->offset = ALIGN_DOWN(offset, bdev_logical_block_size(bdev));
390         if (iomap->offset >= isize)
391                 return -EIO;
392         iomap->type = IOMAP_MAPPED;
393         iomap->addr = iomap->offset;
394         iomap->length = isize - iomap->offset;
395         iomap->flags |= IOMAP_F_BUFFER_HEAD; /* noop for !CONFIG_BUFFER_HEAD */
396         return 0;
397 }
398
399 static const struct iomap_ops blkdev_iomap_ops = {
400         .iomap_begin            = blkdev_iomap_begin,
401 };
402
403 #ifdef CONFIG_BUFFER_HEAD
404 static int blkdev_get_block(struct inode *inode, sector_t iblock,
405                 struct buffer_head *bh, int create)
406 {
407         bh->b_bdev = I_BDEV(inode);
408         bh->b_blocknr = iblock;
409         set_buffer_mapped(bh);
410         return 0;
411 }
412
413 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
414 {
415         return block_write_full_page(page, blkdev_get_block, wbc);
416 }
417
418 static int blkdev_read_folio(struct file *file, struct folio *folio)
419 {
420         return block_read_full_folio(folio, blkdev_get_block);
421 }
422
423 static void blkdev_readahead(struct readahead_control *rac)
424 {
425         mpage_readahead(rac, blkdev_get_block);
426 }
427
428 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
429                 loff_t pos, unsigned len, struct page **pagep, void **fsdata)
430 {
431         return block_write_begin(mapping, pos, len, pagep, blkdev_get_block);
432 }
433
434 static int blkdev_write_end(struct file *file, struct address_space *mapping,
435                 loff_t pos, unsigned len, unsigned copied, struct page *page,
436                 void *fsdata)
437 {
438         int ret;
439         ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
440
441         unlock_page(page);
442         put_page(page);
443
444         return ret;
445 }
446
447 const struct address_space_operations def_blk_aops = {
448         .dirty_folio    = block_dirty_folio,
449         .invalidate_folio = block_invalidate_folio,
450         .read_folio     = blkdev_read_folio,
451         .readahead      = blkdev_readahead,
452         .writepage      = blkdev_writepage,
453         .write_begin    = blkdev_write_begin,
454         .write_end      = blkdev_write_end,
455         .migrate_folio  = buffer_migrate_folio_norefs,
456         .is_dirty_writeback = buffer_check_dirty_writeback,
457 };
458 #else /* CONFIG_BUFFER_HEAD */
459 static int blkdev_read_folio(struct file *file, struct folio *folio)
460 {
461         return iomap_read_folio(folio, &blkdev_iomap_ops);
462 }
463
464 static void blkdev_readahead(struct readahead_control *rac)
465 {
466         iomap_readahead(rac, &blkdev_iomap_ops);
467 }
468
469 static int blkdev_map_blocks(struct iomap_writepage_ctx *wpc,
470                 struct inode *inode, loff_t offset)
471 {
472         loff_t isize = i_size_read(inode);
473
474         if (WARN_ON_ONCE(offset >= isize))
475                 return -EIO;
476         if (offset >= wpc->iomap.offset &&
477             offset < wpc->iomap.offset + wpc->iomap.length)
478                 return 0;
479         return blkdev_iomap_begin(inode, offset, isize - offset,
480                                   IOMAP_WRITE, &wpc->iomap, NULL);
481 }
482
483 static const struct iomap_writeback_ops blkdev_writeback_ops = {
484         .map_blocks             = blkdev_map_blocks,
485 };
486
487 static int blkdev_writepages(struct address_space *mapping,
488                 struct writeback_control *wbc)
489 {
490         struct iomap_writepage_ctx wpc = { };
491
492         return iomap_writepages(mapping, wbc, &wpc, &blkdev_writeback_ops);
493 }
494
495 const struct address_space_operations def_blk_aops = {
496         .dirty_folio    = filemap_dirty_folio,
497         .release_folio          = iomap_release_folio,
498         .invalidate_folio       = iomap_invalidate_folio,
499         .read_folio             = blkdev_read_folio,
500         .readahead              = blkdev_readahead,
501         .writepages             = blkdev_writepages,
502         .is_partially_uptodate  = iomap_is_partially_uptodate,
503         .error_remove_page      = generic_error_remove_page,
504         .migrate_folio          = filemap_migrate_folio,
505 };
506 #endif /* CONFIG_BUFFER_HEAD */
507
508 /*
509  * for a block special file file_inode(file)->i_size is zero
510  * so we compute the size by hand (just as in block_read/write above)
511  */
512 static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
513 {
514         struct inode *bd_inode = bdev_file_inode(file);
515         loff_t retval;
516
517         inode_lock(bd_inode);
518         retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
519         inode_unlock(bd_inode);
520         return retval;
521 }
522
523 static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
524                 int datasync)
525 {
526         struct block_device *bdev = I_BDEV(filp->f_mapping->host);
527         int error;
528
529         error = file_write_and_wait_range(filp, start, end);
530         if (error)
531                 return error;
532
533         /*
534          * There is no need to serialise calls to blkdev_issue_flush with
535          * i_mutex and doing so causes performance issues with concurrent
536          * O_SYNC writers to a block device.
537          */
538         error = blkdev_issue_flush(bdev);
539         if (error == -EOPNOTSUPP)
540                 error = 0;
541
542         return error;
543 }
544
545 blk_mode_t file_to_blk_mode(struct file *file)
546 {
547         blk_mode_t mode = 0;
548
549         if (file->f_mode & FMODE_READ)
550                 mode |= BLK_OPEN_READ;
551         if (file->f_mode & FMODE_WRITE)
552                 mode |= BLK_OPEN_WRITE;
553         if (file->private_data)
554                 mode |= BLK_OPEN_EXCL;
555         if (file->f_flags & O_NDELAY)
556                 mode |= BLK_OPEN_NDELAY;
557
558         /*
559          * If all bits in O_ACCMODE set (aka O_RDWR | O_WRONLY), the floppy
560          * driver has historically allowed ioctls as if the file was opened for
561          * writing, but does not allow and actual reads or writes.
562          */
563         if ((file->f_flags & O_ACCMODE) == (O_RDWR | O_WRONLY))
564                 mode |= BLK_OPEN_WRITE_IOCTL;
565
566         return mode;
567 }
568
569 static int blkdev_open(struct inode *inode, struct file *filp)
570 {
571         struct block_device *bdev;
572
573         /*
574          * Preserve backwards compatibility and allow large file access
575          * even if userspace doesn't ask for it explicitly. Some mkfs
576          * binary needs it. We might want to drop this workaround
577          * during an unstable branch.
578          */
579         filp->f_flags |= O_LARGEFILE;
580         filp->f_mode |= FMODE_BUF_RASYNC | FMODE_CAN_ODIRECT;
581
582         /*
583          * Use the file private data to store the holder for exclusive openes.
584          * file_to_blk_mode relies on it being present to set BLK_OPEN_EXCL.
585          */
586         if (filp->f_flags & O_EXCL)
587                 filp->private_data = filp;
588
589         bdev = blkdev_get_by_dev(inode->i_rdev, file_to_blk_mode(filp),
590                                  filp->private_data, NULL);
591         if (IS_ERR(bdev))
592                 return PTR_ERR(bdev);
593
594         if (bdev_nowait(bdev))
595                 filp->f_mode |= FMODE_NOWAIT;
596
597         filp->f_mapping = bdev->bd_inode->i_mapping;
598         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
599         return 0;
600 }
601
602 static int blkdev_release(struct inode *inode, struct file *filp)
603 {
604         blkdev_put(I_BDEV(filp->f_mapping->host), filp->private_data);
605         return 0;
606 }
607
608 static ssize_t
609 blkdev_direct_write(struct kiocb *iocb, struct iov_iter *from)
610 {
611         size_t count = iov_iter_count(from);
612         ssize_t written;
613
614         written = kiocb_invalidate_pages(iocb, count);
615         if (written) {
616                 if (written == -EBUSY)
617                         return 0;
618                 return written;
619         }
620
621         written = blkdev_direct_IO(iocb, from);
622         if (written > 0) {
623                 kiocb_invalidate_post_direct_write(iocb, count);
624                 iocb->ki_pos += written;
625                 count -= written;
626         }
627         if (written != -EIOCBQUEUED)
628                 iov_iter_revert(from, count - iov_iter_count(from));
629         return written;
630 }
631
632 static ssize_t blkdev_buffered_write(struct kiocb *iocb, struct iov_iter *from)
633 {
634         return iomap_file_buffered_write(iocb, from, &blkdev_iomap_ops);
635 }
636
637 /*
638  * Write data to the block device.  Only intended for the block device itself
639  * and the raw driver which basically is a fake block device.
640  *
641  * Does not take i_mutex for the write and thus is not for general purpose
642  * use.
643  */
644 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
645 {
646         struct file *file = iocb->ki_filp;
647         struct block_device *bdev = I_BDEV(file->f_mapping->host);
648         struct inode *bd_inode = bdev->bd_inode;
649         loff_t size = bdev_nr_bytes(bdev);
650         size_t shorted = 0;
651         ssize_t ret;
652
653         if (bdev_read_only(bdev))
654                 return -EPERM;
655
656         if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
657                 return -ETXTBSY;
658
659         if (!iov_iter_count(from))
660                 return 0;
661
662         if (iocb->ki_pos >= size)
663                 return -ENOSPC;
664
665         if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
666                 return -EOPNOTSUPP;
667
668         size -= iocb->ki_pos;
669         if (iov_iter_count(from) > size) {
670                 shorted = iov_iter_count(from) - size;
671                 iov_iter_truncate(from, size);
672         }
673
674         ret = file_update_time(file);
675         if (ret)
676                 return ret;
677
678         if (iocb->ki_flags & IOCB_DIRECT) {
679                 ret = blkdev_direct_write(iocb, from);
680                 if (ret >= 0 && iov_iter_count(from))
681                         ret = direct_write_fallback(iocb, from, ret,
682                                         blkdev_buffered_write(iocb, from));
683         } else {
684                 ret = blkdev_buffered_write(iocb, from);
685         }
686
687         if (ret > 0)
688                 ret = generic_write_sync(iocb, ret);
689         iov_iter_reexpand(from, iov_iter_count(from) + shorted);
690         return ret;
691 }
692
693 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
694 {
695         struct block_device *bdev = I_BDEV(iocb->ki_filp->f_mapping->host);
696         loff_t size = bdev_nr_bytes(bdev);
697         loff_t pos = iocb->ki_pos;
698         size_t shorted = 0;
699         ssize_t ret = 0;
700         size_t count;
701
702         if (unlikely(pos + iov_iter_count(to) > size)) {
703                 if (pos >= size)
704                         return 0;
705                 size -= pos;
706                 shorted = iov_iter_count(to) - size;
707                 iov_iter_truncate(to, size);
708         }
709
710         count = iov_iter_count(to);
711         if (!count)
712                 goto reexpand; /* skip atime */
713
714         if (iocb->ki_flags & IOCB_DIRECT) {
715                 ret = kiocb_write_and_wait(iocb, count);
716                 if (ret < 0)
717                         goto reexpand;
718                 file_accessed(iocb->ki_filp);
719
720                 ret = blkdev_direct_IO(iocb, to);
721                 if (ret >= 0) {
722                         iocb->ki_pos += ret;
723                         count -= ret;
724                 }
725                 iov_iter_revert(to, count - iov_iter_count(to));
726                 if (ret < 0 || !count)
727                         goto reexpand;
728         }
729
730         ret = filemap_read(iocb, to, ret);
731
732 reexpand:
733         if (unlikely(shorted))
734                 iov_iter_reexpand(to, iov_iter_count(to) + shorted);
735         return ret;
736 }
737
738 #define BLKDEV_FALLOC_FL_SUPPORTED                                      \
739                 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
740                  FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
741
742 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
743                              loff_t len)
744 {
745         struct inode *inode = bdev_file_inode(file);
746         struct block_device *bdev = I_BDEV(inode);
747         loff_t end = start + len - 1;
748         loff_t isize;
749         int error;
750
751         /* Fail if we don't recognize the flags. */
752         if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
753                 return -EOPNOTSUPP;
754
755         /* Don't go off the end of the device. */
756         isize = bdev_nr_bytes(bdev);
757         if (start >= isize)
758                 return -EINVAL;
759         if (end >= isize) {
760                 if (mode & FALLOC_FL_KEEP_SIZE) {
761                         len = isize - start;
762                         end = start + len - 1;
763                 } else
764                         return -EINVAL;
765         }
766
767         /*
768          * Don't allow IO that isn't aligned to logical block size.
769          */
770         if ((start | len) & (bdev_logical_block_size(bdev) - 1))
771                 return -EINVAL;
772
773         filemap_invalidate_lock(inode->i_mapping);
774
775         /*
776          * Invalidate the page cache, including dirty pages, for valid
777          * de-allocate mode calls to fallocate().
778          */
779         switch (mode) {
780         case FALLOC_FL_ZERO_RANGE:
781         case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
782                 error = truncate_bdev_range(bdev, file_to_blk_mode(file), start, end);
783                 if (error)
784                         goto fail;
785
786                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
787                                              len >> SECTOR_SHIFT, GFP_KERNEL,
788                                              BLKDEV_ZERO_NOUNMAP);
789                 break;
790         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
791                 error = truncate_bdev_range(bdev, file_to_blk_mode(file), start, end);
792                 if (error)
793                         goto fail;
794
795                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
796                                              len >> SECTOR_SHIFT, GFP_KERNEL,
797                                              BLKDEV_ZERO_NOFALLBACK);
798                 break;
799         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
800                 error = truncate_bdev_range(bdev, file_to_blk_mode(file), start, end);
801                 if (error)
802                         goto fail;
803
804                 error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
805                                              len >> SECTOR_SHIFT, GFP_KERNEL);
806                 break;
807         default:
808                 error = -EOPNOTSUPP;
809         }
810
811  fail:
812         filemap_invalidate_unlock(inode->i_mapping);
813         return error;
814 }
815
816 static int blkdev_mmap(struct file *file, struct vm_area_struct *vma)
817 {
818         struct inode *bd_inode = bdev_file_inode(file);
819
820         if (bdev_read_only(I_BDEV(bd_inode)))
821                 return generic_file_readonly_mmap(file, vma);
822
823         return generic_file_mmap(file, vma);
824 }
825
826 const struct file_operations def_blk_fops = {
827         .open           = blkdev_open,
828         .release        = blkdev_release,
829         .llseek         = blkdev_llseek,
830         .read_iter      = blkdev_read_iter,
831         .write_iter     = blkdev_write_iter,
832         .iopoll         = iocb_bio_iopoll,
833         .mmap           = blkdev_mmap,
834         .fsync          = blkdev_fsync,
835         .unlocked_ioctl = blkdev_ioctl,
836 #ifdef CONFIG_COMPAT
837         .compat_ioctl   = compat_blkdev_ioctl,
838 #endif
839         .splice_read    = filemap_splice_read,
840         .splice_write   = iter_file_splice_write,
841         .fallocate      = blkdev_fallocate,
842 };
843
844 static __init int blkdev_init(void)
845 {
846         return bioset_init(&blkdev_dio_pool, 4,
847                                 offsetof(struct blkdev_dio, bio),
848                                 BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
849 }
850 module_init(blkdev_init);