GNU Linux-libre 5.19-rc6-gnu
[releases.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/module.h>
19 #include "blk.h"
20
21 static inline struct inode *bdev_file_inode(struct file *file)
22 {
23         return file->f_mapping->host;
24 }
25
26 static int blkdev_get_block(struct inode *inode, sector_t iblock,
27                 struct buffer_head *bh, int create)
28 {
29         bh->b_bdev = I_BDEV(inode);
30         bh->b_blocknr = iblock;
31         set_buffer_mapped(bh);
32         return 0;
33 }
34
35 static unsigned int dio_bio_write_op(struct kiocb *iocb)
36 {
37         unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
38
39         /* avoid the need for a I/O completion work item */
40         if (iocb->ki_flags & IOCB_DSYNC)
41                 op |= REQ_FUA;
42         return op;
43 }
44
45 #define DIO_INLINE_BIO_VECS 4
46
47 static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
48                 struct iov_iter *iter, unsigned int nr_pages)
49 {
50         struct block_device *bdev = iocb->ki_filp->private_data;
51         struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
52         loff_t pos = iocb->ki_pos;
53         bool should_dirty = false;
54         struct bio bio;
55         ssize_t ret;
56
57         if ((pos | iov_iter_alignment(iter)) &
58             (bdev_logical_block_size(bdev) - 1))
59                 return -EINVAL;
60
61         if (nr_pages <= DIO_INLINE_BIO_VECS)
62                 vecs = inline_vecs;
63         else {
64                 vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
65                                      GFP_KERNEL);
66                 if (!vecs)
67                         return -ENOMEM;
68         }
69
70         if (iov_iter_rw(iter) == READ) {
71                 bio_init(&bio, bdev, vecs, nr_pages, REQ_OP_READ);
72                 if (iter_is_iovec(iter))
73                         should_dirty = true;
74         } else {
75                 bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb));
76         }
77         bio.bi_iter.bi_sector = pos >> SECTOR_SHIFT;
78         bio.bi_ioprio = iocb->ki_ioprio;
79
80         ret = bio_iov_iter_get_pages(&bio, iter);
81         if (unlikely(ret))
82                 goto out;
83         ret = bio.bi_iter.bi_size;
84
85         if (iov_iter_rw(iter) == WRITE)
86                 task_io_account_write(ret);
87
88         if (iocb->ki_flags & IOCB_NOWAIT)
89                 bio.bi_opf |= REQ_NOWAIT;
90
91         submit_bio_wait(&bio);
92
93         bio_release_pages(&bio, should_dirty);
94         if (unlikely(bio.bi_status))
95                 ret = blk_status_to_errno(bio.bi_status);
96
97 out:
98         if (vecs != inline_vecs)
99                 kfree(vecs);
100
101         bio_uninit(&bio);
102
103         return ret;
104 }
105
106 enum {
107         DIO_SHOULD_DIRTY        = 1,
108         DIO_IS_SYNC             = 2,
109 };
110
111 struct blkdev_dio {
112         union {
113                 struct kiocb            *iocb;
114                 struct task_struct      *waiter;
115         };
116         size_t                  size;
117         atomic_t                ref;
118         unsigned int            flags;
119         struct bio              bio ____cacheline_aligned_in_smp;
120 };
121
122 static struct bio_set blkdev_dio_pool;
123
124 static void blkdev_bio_end_io(struct bio *bio)
125 {
126         struct blkdev_dio *dio = bio->bi_private;
127         bool should_dirty = dio->flags & DIO_SHOULD_DIRTY;
128
129         if (bio->bi_status && !dio->bio.bi_status)
130                 dio->bio.bi_status = bio->bi_status;
131
132         if (atomic_dec_and_test(&dio->ref)) {
133                 if (!(dio->flags & DIO_IS_SYNC)) {
134                         struct kiocb *iocb = dio->iocb;
135                         ssize_t ret;
136
137                         WRITE_ONCE(iocb->private, NULL);
138
139                         if (likely(!dio->bio.bi_status)) {
140                                 ret = dio->size;
141                                 iocb->ki_pos += ret;
142                         } else {
143                                 ret = blk_status_to_errno(dio->bio.bi_status);
144                         }
145
146                         dio->iocb->ki_complete(iocb, ret);
147                         bio_put(&dio->bio);
148                 } else {
149                         struct task_struct *waiter = dio->waiter;
150
151                         WRITE_ONCE(dio->waiter, NULL);
152                         blk_wake_io_task(waiter);
153                 }
154         }
155
156         if (should_dirty) {
157                 bio_check_pages_dirty(bio);
158         } else {
159                 bio_release_pages(bio, false);
160                 bio_put(bio);
161         }
162 }
163
164 static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
165                 unsigned int nr_pages)
166 {
167         struct block_device *bdev = iocb->ki_filp->private_data;
168         struct blk_plug plug;
169         struct blkdev_dio *dio;
170         struct bio *bio;
171         bool is_read = (iov_iter_rw(iter) == READ), is_sync;
172         unsigned int opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
173         loff_t pos = iocb->ki_pos;
174         int ret = 0;
175
176         if ((pos | iov_iter_alignment(iter)) &
177             (bdev_logical_block_size(bdev) - 1))
178                 return -EINVAL;
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 && iter_is_iovec(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_private = dio;
210                 bio->bi_end_io = blkdev_bio_end_io;
211                 bio->bi_ioprio = iocb->ki_ioprio;
212
213                 ret = bio_iov_iter_get_pages(bio, iter);
214                 if (unlikely(ret)) {
215                         bio->bi_status = BLK_STS_IOERR;
216                         bio_endio(bio);
217                         break;
218                 }
219
220                 if (is_read) {
221                         if (dio->flags & DIO_SHOULD_DIRTY)
222                                 bio_set_pages_dirty(bio);
223                 } else {
224                         task_io_account_write(bio->bi_iter.bi_size);
225                 }
226                 if (iocb->ki_flags & IOCB_NOWAIT)
227                         bio->bi_opf |= REQ_NOWAIT;
228
229                 dio->size += bio->bi_iter.bi_size;
230                 pos += bio->bi_iter.bi_size;
231
232                 nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS);
233                 if (!nr_pages) {
234                         submit_bio(bio);
235                         break;
236                 }
237                 atomic_inc(&dio->ref);
238                 submit_bio(bio);
239                 bio = bio_alloc(bdev, nr_pages, opf, GFP_KERNEL);
240         }
241
242         blk_finish_plug(&plug);
243
244         if (!is_sync)
245                 return -EIOCBQUEUED;
246
247         for (;;) {
248                 set_current_state(TASK_UNINTERRUPTIBLE);
249                 if (!READ_ONCE(dio->waiter))
250                         break;
251                 blk_io_schedule();
252         }
253         __set_current_state(TASK_RUNNING);
254
255         if (!ret)
256                 ret = blk_status_to_errno(dio->bio.bi_status);
257         if (likely(!ret))
258                 ret = dio->size;
259
260         bio_put(&dio->bio);
261         return ret;
262 }
263
264 static void blkdev_bio_end_io_async(struct bio *bio)
265 {
266         struct blkdev_dio *dio = container_of(bio, struct blkdev_dio, bio);
267         struct kiocb *iocb = dio->iocb;
268         ssize_t ret;
269
270         WRITE_ONCE(iocb->private, NULL);
271
272         if (likely(!bio->bi_status)) {
273                 ret = dio->size;
274                 iocb->ki_pos += ret;
275         } else {
276                 ret = blk_status_to_errno(bio->bi_status);
277         }
278
279         iocb->ki_complete(iocb, ret);
280
281         if (dio->flags & DIO_SHOULD_DIRTY) {
282                 bio_check_pages_dirty(bio);
283         } else {
284                 bio_release_pages(bio, false);
285                 bio_put(bio);
286         }
287 }
288
289 static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
290                                         struct iov_iter *iter,
291                                         unsigned int nr_pages)
292 {
293         struct block_device *bdev = iocb->ki_filp->private_data;
294         bool is_read = iov_iter_rw(iter) == READ;
295         unsigned int opf = is_read ? REQ_OP_READ : dio_bio_write_op(iocb);
296         struct blkdev_dio *dio;
297         struct bio *bio;
298         loff_t pos = iocb->ki_pos;
299         int ret = 0;
300
301         if ((pos | iov_iter_alignment(iter)) &
302             (bdev_logical_block_size(bdev) - 1))
303                 return -EINVAL;
304
305         if (iocb->ki_flags & IOCB_ALLOC_CACHE)
306                 opf |= REQ_ALLOC_CACHE;
307         bio = bio_alloc_bioset(bdev, nr_pages, opf, GFP_KERNEL,
308                                &blkdev_dio_pool);
309         dio = container_of(bio, struct blkdev_dio, bio);
310         dio->flags = 0;
311         dio->iocb = iocb;
312         bio->bi_iter.bi_sector = pos >> SECTOR_SHIFT;
313         bio->bi_end_io = blkdev_bio_end_io_async;
314         bio->bi_ioprio = iocb->ki_ioprio;
315
316         if (iov_iter_is_bvec(iter)) {
317                 /*
318                  * Users don't rely on the iterator being in any particular
319                  * state for async I/O returning -EIOCBQUEUED, hence we can
320                  * avoid expensive iov_iter_advance(). Bypass
321                  * bio_iov_iter_get_pages() and set the bvec directly.
322                  */
323                 bio_iov_bvec_set(bio, iter);
324         } else {
325                 ret = bio_iov_iter_get_pages(bio, iter);
326                 if (unlikely(ret)) {
327                         bio_put(bio);
328                         return ret;
329                 }
330         }
331         dio->size = bio->bi_iter.bi_size;
332
333         if (is_read) {
334                 if (iter_is_iovec(iter)) {
335                         dio->flags |= DIO_SHOULD_DIRTY;
336                         bio_set_pages_dirty(bio);
337                 }
338         } else {
339                 task_io_account_write(bio->bi_iter.bi_size);
340         }
341
342         if (iocb->ki_flags & IOCB_HIPRI) {
343                 bio->bi_opf |= REQ_POLLED | REQ_NOWAIT;
344                 submit_bio(bio);
345                 WRITE_ONCE(iocb->private, bio);
346         } else {
347                 if (iocb->ki_flags & IOCB_NOWAIT)
348                         bio->bi_opf |= REQ_NOWAIT;
349                 submit_bio(bio);
350         }
351         return -EIOCBQUEUED;
352 }
353
354 static ssize_t blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
355 {
356         unsigned int nr_pages;
357
358         if (!iov_iter_count(iter))
359                 return 0;
360
361         nr_pages = bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS + 1);
362         if (likely(nr_pages <= BIO_MAX_VECS)) {
363                 if (is_sync_kiocb(iocb))
364                         return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
365                 return __blkdev_direct_IO_async(iocb, iter, nr_pages);
366         }
367         return __blkdev_direct_IO(iocb, iter, bio_max_segs(nr_pages));
368 }
369
370 static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
371 {
372         return block_write_full_page(page, blkdev_get_block, wbc);
373 }
374
375 static int blkdev_read_folio(struct file *file, struct folio *folio)
376 {
377         return block_read_full_folio(folio, blkdev_get_block);
378 }
379
380 static void blkdev_readahead(struct readahead_control *rac)
381 {
382         mpage_readahead(rac, blkdev_get_block);
383 }
384
385 static int blkdev_write_begin(struct file *file, struct address_space *mapping,
386                 loff_t pos, unsigned len, struct page **pagep, void **fsdata)
387 {
388         return block_write_begin(mapping, pos, len, pagep, blkdev_get_block);
389 }
390
391 static int blkdev_write_end(struct file *file, struct address_space *mapping,
392                 loff_t pos, unsigned len, unsigned copied, struct page *page,
393                 void *fsdata)
394 {
395         int ret;
396         ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
397
398         unlock_page(page);
399         put_page(page);
400
401         return ret;
402 }
403
404 static int blkdev_writepages(struct address_space *mapping,
405                              struct writeback_control *wbc)
406 {
407         return generic_writepages(mapping, wbc);
408 }
409
410 const struct address_space_operations def_blk_aops = {
411         .dirty_folio    = block_dirty_folio,
412         .invalidate_folio = block_invalidate_folio,
413         .read_folio     = blkdev_read_folio,
414         .readahead      = blkdev_readahead,
415         .writepage      = blkdev_writepage,
416         .write_begin    = blkdev_write_begin,
417         .write_end      = blkdev_write_end,
418         .writepages     = blkdev_writepages,
419         .direct_IO      = blkdev_direct_IO,
420         .migratepage    = buffer_migrate_page_norefs,
421         .is_dirty_writeback = buffer_check_dirty_writeback,
422 };
423
424 /*
425  * for a block special file file_inode(file)->i_size is zero
426  * so we compute the size by hand (just as in block_read/write above)
427  */
428 static loff_t blkdev_llseek(struct file *file, loff_t offset, int whence)
429 {
430         struct inode *bd_inode = bdev_file_inode(file);
431         loff_t retval;
432
433         inode_lock(bd_inode);
434         retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
435         inode_unlock(bd_inode);
436         return retval;
437 }
438
439 static int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
440                 int datasync)
441 {
442         struct block_device *bdev = filp->private_data;
443         int error;
444
445         error = file_write_and_wait_range(filp, start, end);
446         if (error)
447                 return error;
448
449         /*
450          * There is no need to serialise calls to blkdev_issue_flush with
451          * i_mutex and doing so causes performance issues with concurrent
452          * O_SYNC writers to a block device.
453          */
454         error = blkdev_issue_flush(bdev);
455         if (error == -EOPNOTSUPP)
456                 error = 0;
457
458         return error;
459 }
460
461 static int blkdev_open(struct inode *inode, struct file *filp)
462 {
463         struct block_device *bdev;
464
465         /*
466          * Preserve backwards compatibility and allow large file access
467          * even if userspace doesn't ask for it explicitly. Some mkfs
468          * binary needs it. We might want to drop this workaround
469          * during an unstable branch.
470          */
471         filp->f_flags |= O_LARGEFILE;
472         filp->f_mode |= FMODE_NOWAIT | FMODE_BUF_RASYNC;
473
474         if (filp->f_flags & O_NDELAY)
475                 filp->f_mode |= FMODE_NDELAY;
476         if (filp->f_flags & O_EXCL)
477                 filp->f_mode |= FMODE_EXCL;
478         if ((filp->f_flags & O_ACCMODE) == 3)
479                 filp->f_mode |= FMODE_WRITE_IOCTL;
480
481         bdev = blkdev_get_by_dev(inode->i_rdev, filp->f_mode, filp);
482         if (IS_ERR(bdev))
483                 return PTR_ERR(bdev);
484
485         filp->private_data = bdev;
486         filp->f_mapping = bdev->bd_inode->i_mapping;
487         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
488         return 0;
489 }
490
491 static int blkdev_close(struct inode *inode, struct file *filp)
492 {
493         struct block_device *bdev = filp->private_data;
494
495         blkdev_put(bdev, filp->f_mode);
496         return 0;
497 }
498
499 /*
500  * Write data to the block device.  Only intended for the block device itself
501  * and the raw driver which basically is a fake block device.
502  *
503  * Does not take i_mutex for the write and thus is not for general purpose
504  * use.
505  */
506 static ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
507 {
508         struct block_device *bdev = iocb->ki_filp->private_data;
509         struct inode *bd_inode = bdev->bd_inode;
510         loff_t size = bdev_nr_bytes(bdev);
511         struct blk_plug plug;
512         size_t shorted = 0;
513         ssize_t ret;
514
515         if (bdev_read_only(bdev))
516                 return -EPERM;
517
518         if (IS_SWAPFILE(bd_inode) && !is_hibernate_resume_dev(bd_inode->i_rdev))
519                 return -ETXTBSY;
520
521         if (!iov_iter_count(from))
522                 return 0;
523
524         if (iocb->ki_pos >= size)
525                 return -ENOSPC;
526
527         if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
528                 return -EOPNOTSUPP;
529
530         size -= iocb->ki_pos;
531         if (iov_iter_count(from) > size) {
532                 shorted = iov_iter_count(from) - size;
533                 iov_iter_truncate(from, size);
534         }
535
536         blk_start_plug(&plug);
537         ret = __generic_file_write_iter(iocb, from);
538         if (ret > 0)
539                 ret = generic_write_sync(iocb, ret);
540         iov_iter_reexpand(from, iov_iter_count(from) + shorted);
541         blk_finish_plug(&plug);
542         return ret;
543 }
544
545 static ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
546 {
547         struct block_device *bdev = iocb->ki_filp->private_data;
548         loff_t size = bdev_nr_bytes(bdev);
549         loff_t pos = iocb->ki_pos;
550         size_t shorted = 0;
551         ssize_t ret = 0;
552         size_t count;
553
554         if (unlikely(pos + iov_iter_count(to) > size)) {
555                 if (pos >= size)
556                         return 0;
557                 size -= pos;
558                 shorted = iov_iter_count(to) - size;
559                 iov_iter_truncate(to, size);
560         }
561
562         count = iov_iter_count(to);
563         if (!count)
564                 goto reexpand; /* skip atime */
565
566         if (iocb->ki_flags & IOCB_DIRECT) {
567                 struct address_space *mapping = iocb->ki_filp->f_mapping;
568
569                 if (iocb->ki_flags & IOCB_NOWAIT) {
570                         if (filemap_range_needs_writeback(mapping, pos,
571                                                           pos + count - 1)) {
572                                 ret = -EAGAIN;
573                                 goto reexpand;
574                         }
575                 } else {
576                         ret = filemap_write_and_wait_range(mapping, pos,
577                                                            pos + count - 1);
578                         if (ret < 0)
579                                 goto reexpand;
580                 }
581
582                 file_accessed(iocb->ki_filp);
583
584                 ret = blkdev_direct_IO(iocb, to);
585                 if (ret >= 0) {
586                         iocb->ki_pos += ret;
587                         count -= ret;
588                 }
589                 iov_iter_revert(to, count - iov_iter_count(to));
590                 if (ret < 0 || !count)
591                         goto reexpand;
592         }
593
594         ret = filemap_read(iocb, to, ret);
595
596 reexpand:
597         if (unlikely(shorted))
598                 iov_iter_reexpand(to, iov_iter_count(to) + shorted);
599         return ret;
600 }
601
602 #define BLKDEV_FALLOC_FL_SUPPORTED                                      \
603                 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |           \
604                  FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
605
606 static long blkdev_fallocate(struct file *file, int mode, loff_t start,
607                              loff_t len)
608 {
609         struct inode *inode = bdev_file_inode(file);
610         struct block_device *bdev = I_BDEV(inode);
611         loff_t end = start + len - 1;
612         loff_t isize;
613         int error;
614
615         /* Fail if we don't recognize the flags. */
616         if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
617                 return -EOPNOTSUPP;
618
619         /* Don't go off the end of the device. */
620         isize = bdev_nr_bytes(bdev);
621         if (start >= isize)
622                 return -EINVAL;
623         if (end >= isize) {
624                 if (mode & FALLOC_FL_KEEP_SIZE) {
625                         len = isize - start;
626                         end = start + len - 1;
627                 } else
628                         return -EINVAL;
629         }
630
631         /*
632          * Don't allow IO that isn't aligned to logical block size.
633          */
634         if ((start | len) & (bdev_logical_block_size(bdev) - 1))
635                 return -EINVAL;
636
637         filemap_invalidate_lock(inode->i_mapping);
638
639         /* Invalidate the page cache, including dirty pages. */
640         error = truncate_bdev_range(bdev, file->f_mode, start, end);
641         if (error)
642                 goto fail;
643
644         switch (mode) {
645         case FALLOC_FL_ZERO_RANGE:
646         case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
647                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
648                                              len >> SECTOR_SHIFT, GFP_KERNEL,
649                                              BLKDEV_ZERO_NOUNMAP);
650                 break;
651         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
652                 error = blkdev_issue_zeroout(bdev, start >> SECTOR_SHIFT,
653                                              len >> SECTOR_SHIFT, GFP_KERNEL,
654                                              BLKDEV_ZERO_NOFALLBACK);
655                 break;
656         case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
657                 error = blkdev_issue_discard(bdev, start >> SECTOR_SHIFT,
658                                              len >> SECTOR_SHIFT, GFP_KERNEL);
659                 break;
660         default:
661                 error = -EOPNOTSUPP;
662         }
663
664  fail:
665         filemap_invalidate_unlock(inode->i_mapping);
666         return error;
667 }
668
669 const struct file_operations def_blk_fops = {
670         .open           = blkdev_open,
671         .release        = blkdev_close,
672         .llseek         = blkdev_llseek,
673         .read_iter      = blkdev_read_iter,
674         .write_iter     = blkdev_write_iter,
675         .iopoll         = iocb_bio_iopoll,
676         .mmap           = generic_file_mmap,
677         .fsync          = blkdev_fsync,
678         .unlocked_ioctl = blkdev_ioctl,
679 #ifdef CONFIG_COMPAT
680         .compat_ioctl   = compat_blkdev_ioctl,
681 #endif
682         .splice_read    = generic_file_splice_read,
683         .splice_write   = iter_file_splice_write,
684         .fallocate      = blkdev_fallocate,
685 };
686
687 static __init int blkdev_init(void)
688 {
689         return bioset_init(&blkdev_dio_pool, 4,
690                                 offsetof(struct blkdev_dio, bio),
691                                 BIOSET_NEED_BVECS|BIOSET_PERCPU_CACHE);
692 }
693 module_init(blkdev_init);