projects/linux·blob v5.4-rc6 · refs

2248 lines · 55.9 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/block_dev.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 * Copyright (C) 2001 Andrea Arcangeli <[email protected]> SuSE
7 */
8
9#include <linux/init.h>
10#include <linux/mm.h>
11#include <linux/fcntl.h>
12#include <linux/slab.h>
13#include <linux/kmod.h>
14#include <linux/major.h>
15#include <linux/device_cgroup.h>
16#include <linux/highmem.h>
17#include <linux/blkdev.h>
18#include <linux/backing-dev.h>
19#include <linux/module.h>
20#include <linux/blkpg.h>
21#include <linux/magic.h>
22#include <linux/dax.h>
23#include <linux/buffer_head.h>
24#include <linux/swap.h>
25#include <linux/pagevec.h>
26#include <linux/writeback.h>
27#include <linux/mpage.h>
28#include <linux/mount.h>
29#include <linux/pseudo_fs.h>
30#include <linux/uio.h>
31#include <linux/namei.h>
32#include <linux/log2.h>
33#include <linux/cleancache.h>
34#include <linux/task_io_accounting_ops.h>
35#include <linux/falloc.h>
36#include <linux/uaccess.h>
37#include "internal.h"
38
39struct bdev_inode {
40 struct block_device bdev;
41 struct inode vfs_inode;
42};
43
44static const struct address_space_operations def_blk_aops;
45
46static inline struct bdev_inode *BDEV_I(struct inode *inode)
47{
48 return container_of(inode, struct bdev_inode, vfs_inode);
49}
50
51struct block_device *I_BDEV(struct inode *inode)
52{
53 return &BDEV_I(inode)->bdev;
54}
55EXPORT_SYMBOL(I_BDEV);
56
57static void bdev_write_inode(struct block_device *bdev)
58{
59 struct inode *inode = bdev->bd_inode;
60 int ret;
61
62 spin_lock(&inode->i_lock);
63 while (inode->i_state & I_DIRTY) {
64 spin_unlock(&inode->i_lock);
65 ret = write_inode_now(inode, true);
66 if (ret) {
67 char name[BDEVNAME_SIZE];
68 pr_warn_ratelimited("VFS: Dirty inode writeback failed "
69 "for block device %s (err=%d).\n",
70 bdevname(bdev, name), ret);
71 }
72 spin_lock(&inode->i_lock);
73 }
74 spin_unlock(&inode->i_lock);
75}
76
77/* Kill _all_ buffers and pagecache , dirty or not.. */
78void kill_bdev(struct block_device *bdev)
79{
80 struct address_space *mapping = bdev->bd_inode->i_mapping;
81
82 if (mapping->nrpages == 0 && mapping->nrexceptional == 0)
83 return;
84
85 invalidate_bh_lrus();
86 truncate_inode_pages(mapping, 0);
87}
88EXPORT_SYMBOL(kill_bdev);
89
90/* Invalidate clean unused buffers and pagecache. */
91void invalidate_bdev(struct block_device *bdev)
92{
93 struct address_space *mapping = bdev->bd_inode->i_mapping;
94
95 if (mapping->nrpages) {
96 invalidate_bh_lrus();
97 lru_add_drain_all(); /* make sure all lru add caches are flushed */
98 invalidate_mapping_pages(mapping, 0, -1);
99 }
100 /* 99% of the time, we don't need to flush the cleancache on the bdev.
101 * But, for the strange corners, lets be cautious
102 */
103 cleancache_invalidate_inode(mapping);
104}
105EXPORT_SYMBOL(invalidate_bdev);
106
107static void set_init_blocksize(struct block_device *bdev)
108{
109 unsigned bsize = bdev_logical_block_size(bdev);
110 loff_t size = i_size_read(bdev->bd_inode);
111
112 while (bsize < PAGE_SIZE) {
113 if (size & bsize)
114 break;
115 bsize <<= 1;
116 }
117 bdev->bd_block_size = bsize;
118 bdev->bd_inode->i_blkbits = blksize_bits(bsize);
119}
120
121int set_blocksize(struct block_device *bdev, int size)
122{
123 /* Size must be a power of two, and between 512 and PAGE_SIZE */
124 if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size))
125 return -EINVAL;
126
127 /* Size cannot be smaller than the size supported by the device */
128 if (size < bdev_logical_block_size(bdev))
129 return -EINVAL;
130
131 /* Don't change the size if it is same as current */
132 if (bdev->bd_block_size != size) {
133 sync_blockdev(bdev);
134 bdev->bd_block_size = size;
135 bdev->bd_inode->i_blkbits = blksize_bits(size);
136 kill_bdev(bdev);
137 }
138 return 0;
139}
140
141EXPORT_SYMBOL(set_blocksize);
142
143int sb_set_blocksize(struct super_block *sb, int size)
144{
145 if (set_blocksize(sb->s_bdev, size))
146 return 0;
147 /* If we get here, we know size is power of two
148 * and it's value is between 512 and PAGE_SIZE */
149 sb->s_blocksize = size;
150 sb->s_blocksize_bits = blksize_bits(size);
151 return sb->s_blocksize;
152}
153
154EXPORT_SYMBOL(sb_set_blocksize);
155
156int sb_min_blocksize(struct super_block *sb, int size)
157{
158 int minsize = bdev_logical_block_size(sb->s_bdev);
159 if (size < minsize)
160 size = minsize;
161 return sb_set_blocksize(sb, size);
162}
163
164EXPORT_SYMBOL(sb_min_blocksize);
165
166static int
167blkdev_get_block(struct inode *inode, sector_t iblock,
168 struct buffer_head *bh, int create)
169{
170 bh->b_bdev = I_BDEV(inode);
171 bh->b_blocknr = iblock;
172 set_buffer_mapped(bh);
173 return 0;
174}
175
176static struct inode *bdev_file_inode(struct file *file)
177{
178 return file->f_mapping->host;
179}
180
181static unsigned int dio_bio_write_op(struct kiocb *iocb)
182{
183 unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
184
185 /* avoid the need for a I/O completion work item */
186 if (iocb->ki_flags & IOCB_DSYNC)
187 op |= REQ_FUA;
188 return op;
189}
190
191#define DIO_INLINE_BIO_VECS 4
192
193static void blkdev_bio_end_io_simple(struct bio *bio)
194{
195 struct task_struct *waiter = bio->bi_private;
196
197 WRITE_ONCE(bio->bi_private, NULL);
198 blk_wake_io_task(waiter);
199}
200
201static ssize_t
202__blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
203 int nr_pages)
204{
205 struct file *file = iocb->ki_filp;
206 struct block_device *bdev = I_BDEV(bdev_file_inode(file));
207 struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs;
208 loff_t pos = iocb->ki_pos;
209 bool should_dirty = false;
210 struct bio bio;
211 ssize_t ret;
212 blk_qc_t qc;
213
214 if ((pos | iov_iter_alignment(iter)) &
215 (bdev_logical_block_size(bdev) - 1))
216 return -EINVAL;
217
218 if (nr_pages <= DIO_INLINE_BIO_VECS)
219 vecs = inline_vecs;
220 else {
221 vecs = kmalloc_array(nr_pages, sizeof(struct bio_vec),
222 GFP_KERNEL);
223 if (!vecs)
224 return -ENOMEM;
225 }
226
227 bio_init(&bio, vecs, nr_pages);
228 bio_set_dev(&bio, bdev);
229 bio.bi_iter.bi_sector = pos >> 9;
230 bio.bi_write_hint = iocb->ki_hint;
231 bio.bi_private = current;
232 bio.bi_end_io = blkdev_bio_end_io_simple;
233 bio.bi_ioprio = iocb->ki_ioprio;
234
235 ret = bio_iov_iter_get_pages(&bio, iter);
236 if (unlikely(ret))
237 goto out;
238 ret = bio.bi_iter.bi_size;
239
240 if (iov_iter_rw(iter) == READ) {
241 bio.bi_opf = REQ_OP_READ;
242 if (iter_is_iovec(iter))
243 should_dirty = true;
244 } else {
245 bio.bi_opf = dio_bio_write_op(iocb);
246 task_io_account_write(ret);
247 }
248 if (iocb->ki_flags & IOCB_HIPRI)
249 bio_set_polled(&bio, iocb);
250
251 qc = submit_bio(&bio);
252 for (;;) {
253 set_current_state(TASK_UNINTERRUPTIBLE);
254 if (!READ_ONCE(bio.bi_private))
255 break;
256 if (!(iocb->ki_flags & IOCB_HIPRI) ||
257 !blk_poll(bdev_get_queue(bdev), qc, true))
258 io_schedule();
259 }
260 __set_current_state(TASK_RUNNING);
261
262 bio_release_pages(&bio, should_dirty);
263 if (unlikely(bio.bi_status))
264 ret = blk_status_to_errno(bio.bi_status);
265
266out:
267 if (vecs != inline_vecs)
268 kfree(vecs);
269
270 bio_uninit(&bio);
271
272 return ret;
273}
274
275struct blkdev_dio {
276 union {
277 struct kiocb *iocb;
278 struct task_struct *waiter;
279 };
280 size_t size;
281 atomic_t ref;
282 bool multi_bio : 1;
283 bool should_dirty : 1;
284 bool is_sync : 1;
285 struct bio bio;
286};
287
288static struct bio_set blkdev_dio_pool;
289
290static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
291{
292 struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
293 struct request_queue *q = bdev_get_queue(bdev);
294
295 return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
296}
297
298static void blkdev_bio_end_io(struct bio *bio)
299{
300 struct blkdev_dio *dio = bio->bi_private;
301 bool should_dirty = dio->should_dirty;
302
303 if (bio->bi_status && !dio->bio.bi_status)
304 dio->bio.bi_status = bio->bi_status;
305
306 if (!dio->multi_bio || atomic_dec_and_test(&dio->ref)) {
307 if (!dio->is_sync) {
308 struct kiocb *iocb = dio->iocb;
309 ssize_t ret;
310
311 if (likely(!dio->bio.bi_status)) {
312 ret = dio->size;
313 iocb->ki_pos += ret;
314 } else {
315 ret = blk_status_to_errno(dio->bio.bi_status);
316 }
317
318 dio->iocb->ki_complete(iocb, ret, 0);
319 if (dio->multi_bio)
320 bio_put(&dio->bio);
321 } else {
322 struct task_struct *waiter = dio->waiter;
323
324 WRITE_ONCE(dio->waiter, NULL);
325 blk_wake_io_task(waiter);
326 }
327 }
328
329 if (should_dirty) {
330 bio_check_pages_dirty(bio);
331 } else {
332 bio_release_pages(bio, false);
333 bio_put(bio);
334 }
335}
336
337static ssize_t
338__blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
339{
340 struct file *file = iocb->ki_filp;
341 struct inode *inode = bdev_file_inode(file);
342 struct block_device *bdev = I_BDEV(inode);
343 struct blk_plug plug;
344 struct blkdev_dio *dio;
345 struct bio *bio;
346 bool is_poll = (iocb->ki_flags & IOCB_HIPRI) != 0;
347 bool is_read = (iov_iter_rw(iter) == READ), is_sync;
348 loff_t pos = iocb->ki_pos;
349 blk_qc_t qc = BLK_QC_T_NONE;
350 int ret = 0;
351
352 if ((pos | iov_iter_alignment(iter)) &
353 (bdev_logical_block_size(bdev) - 1))
354 return -EINVAL;
355
356 bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, &blkdev_dio_pool);
357
358 dio = container_of(bio, struct blkdev_dio, bio);
359 dio->is_sync = is_sync = is_sync_kiocb(iocb);
360 if (dio->is_sync) {
361 dio->waiter = current;
362 bio_get(bio);
363 } else {
364 dio->iocb = iocb;
365 }
366
367 dio->size = 0;
368 dio->multi_bio = false;
369 dio->should_dirty = is_read && iter_is_iovec(iter);
370
371 /*
372 * Don't plug for HIPRI/polled IO, as those should go straight
373 * to issue
374 */
375 if (!is_poll)
376 blk_start_plug(&plug);
377
378 for (;;) {
379 bio_set_dev(bio, bdev);
380 bio->bi_iter.bi_sector = pos >> 9;
381 bio->bi_write_hint = iocb->ki_hint;
382 bio->bi_private = dio;
383 bio->bi_end_io = blkdev_bio_end_io;
384 bio->bi_ioprio = iocb->ki_ioprio;
385
386 ret = bio_iov_iter_get_pages(bio, iter);
387 if (unlikely(ret)) {
388 bio->bi_status = BLK_STS_IOERR;
389 bio_endio(bio);
390 break;
391 }
392
393 if (is_read) {
394 bio->bi_opf = REQ_OP_READ;
395 if (dio->should_dirty)
396 bio_set_pages_dirty(bio);
397 } else {
398 bio->bi_opf = dio_bio_write_op(iocb);
399 task_io_account_write(bio->bi_iter.bi_size);
400 }
401
402 dio->size += bio->bi_iter.bi_size;
403 pos += bio->bi_iter.bi_size;
404
405 nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);
406 if (!nr_pages) {
407 bool polled = false;
408
409 if (iocb->ki_flags & IOCB_HIPRI) {
410 bio_set_polled(bio, iocb);
411 polled = true;
412 }
413
414 qc = submit_bio(bio);
415
416 if (polled)
417 WRITE_ONCE(iocb->ki_cookie, qc);
418 break;
419 }
420
421 if (!dio->multi_bio) {
422 /*
423 * AIO needs an extra reference to ensure the dio
424 * structure which is embedded into the first bio
425 * stays around.
426 */
427 if (!is_sync)
428 bio_get(bio);
429 dio->multi_bio = true;
430 atomic_set(&dio->ref, 2);
431 } else {
432 atomic_inc(&dio->ref);
433 }
434
435 submit_bio(bio);
436 bio = bio_alloc(GFP_KERNEL, nr_pages);
437 }
438
439 if (!is_poll)
440 blk_finish_plug(&plug);
441
442 if (!is_sync)
443 return -EIOCBQUEUED;
444
445 for (;;) {
446 set_current_state(TASK_UNINTERRUPTIBLE);
447 if (!READ_ONCE(dio->waiter))
448 break;
449
450 if (!(iocb->ki_flags & IOCB_HIPRI) ||
451 !blk_poll(bdev_get_queue(bdev), qc, true))
452 io_schedule();
453 }
454 __set_current_state(TASK_RUNNING);
455
456 if (!ret)
457 ret = blk_status_to_errno(dio->bio.bi_status);
458 if (likely(!ret))
459 ret = dio->size;
460
461 bio_put(&dio->bio);
462 return ret;
463}
464
465static ssize_t
466blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter)
467{
468 int nr_pages;
469
470 nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1);
471 if (!nr_pages)
472 return 0;
473 if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES)
474 return __blkdev_direct_IO_simple(iocb, iter, nr_pages);
475
476 return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES));
477}
478
479static __init int blkdev_init(void)
480{
481 return bioset_init(&blkdev_dio_pool, 4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS);
482}
483module_init(blkdev_init);
484
485int __sync_blockdev(struct block_device *bdev, int wait)
486{
487 if (!bdev)
488 return 0;
489 if (!wait)
490 return filemap_flush(bdev->bd_inode->i_mapping);
491 return filemap_write_and_wait(bdev->bd_inode->i_mapping);
492}
493
494/*
495 * Write out and wait upon all the dirty data associated with a block
496 * device via its mapping. Does not take the superblock lock.
497 */
498int sync_blockdev(struct block_device *bdev)
499{
500 return __sync_blockdev(bdev, 1);
501}
502EXPORT_SYMBOL(sync_blockdev);
503
504/*
505 * Write out and wait upon all dirty data associated with this
506 * device. Filesystem data as well as the underlying block
507 * device. Takes the superblock lock.
508 */
509int fsync_bdev(struct block_device *bdev)
510{
511 struct super_block *sb = get_super(bdev);
512 if (sb) {
513 int res = sync_filesystem(sb);
514 drop_super(sb);
515 return res;
516 }
517 return sync_blockdev(bdev);
518}
519EXPORT_SYMBOL(fsync_bdev);
520
521/**
522 * freeze_bdev -- lock a filesystem and force it into a consistent state
523 * @bdev: blockdevice to lock
524 *
525 * If a superblock is found on this device, we take the s_umount semaphore
526 * on it to make sure nobody unmounts until the snapshot creation is done.
527 * The reference counter (bd_fsfreeze_count) guarantees that only the last
528 * unfreeze process can unfreeze the frozen filesystem actually when multiple
529 * freeze requests arrive simultaneously. It counts up in freeze_bdev() and
530 * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze
531 * actually.
532 */
533struct super_block *freeze_bdev(struct block_device *bdev)
534{
535 struct super_block *sb;
536 int error = 0;
537
538 mutex_lock(&bdev->bd_fsfreeze_mutex);
539 if (++bdev->bd_fsfreeze_count > 1) {
540 /*
541 * We don't even need to grab a reference - the first call
542 * to freeze_bdev grab an active reference and only the last
543 * thaw_bdev drops it.
544 */
545 sb = get_super(bdev);
546 if (sb)
547 drop_super(sb);
548 mutex_unlock(&bdev->bd_fsfreeze_mutex);
549 return sb;
550 }
551
552 sb = get_active_super(bdev);
553 if (!sb)
554 goto out;
555 if (sb->s_op->freeze_super)
556 error = sb->s_op->freeze_super(sb);
557 else
558 error = freeze_super(sb);
559 if (error) {
560 deactivate_super(sb);
561 bdev->bd_fsfreeze_count--;
562 mutex_unlock(&bdev->bd_fsfreeze_mutex);
563 return ERR_PTR(error);
564 }
565 deactivate_super(sb);
566 out:
567 sync_blockdev(bdev);
568 mutex_unlock(&bdev->bd_fsfreeze_mutex);
569 return sb; /* thaw_bdev releases s->s_umount */
570}
571EXPORT_SYMBOL(freeze_bdev);
572
573/**
574 * thaw_bdev -- unlock filesystem
575 * @bdev: blockdevice to unlock
576 * @sb: associated superblock
577 *
578 * Unlocks the filesystem and marks it writeable again after freeze_bdev().
579 */
580int thaw_bdev(struct block_device *bdev, struct super_block *sb)
581{
582 int error = -EINVAL;
583
584 mutex_lock(&bdev->bd_fsfreeze_mutex);
585 if (!bdev->bd_fsfreeze_count)
586 goto out;
587
588 error = 0;
589 if (--bdev->bd_fsfreeze_count > 0)
590 goto out;
591
592 if (!sb)
593 goto out;
594
595 if (sb->s_op->thaw_super)
596 error = sb->s_op->thaw_super(sb);
597 else
598 error = thaw_super(sb);
599 if (error)
600 bdev->bd_fsfreeze_count++;
601out:
602 mutex_unlock(&bdev->bd_fsfreeze_mutex);
603 return error;
604}
605EXPORT_SYMBOL(thaw_bdev);
606
607static int blkdev_writepage(struct page *page, struct writeback_control *wbc)
608{
609 return block_write_full_page(page, blkdev_get_block, wbc);
610}
611
612static int blkdev_readpage(struct file * file, struct page * page)
613{
614 return block_read_full_page(page, blkdev_get_block);
615}
616
617static int blkdev_readpages(struct file *file, struct address_space *mapping,
618 struct list_head *pages, unsigned nr_pages)
619{
620 return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block);
621}
622
623static int blkdev_write_begin(struct file *file, struct address_space *mapping,
624 loff_t pos, unsigned len, unsigned flags,
625 struct page **pagep, void **fsdata)
626{
627 return block_write_begin(mapping, pos, len, flags, pagep,
628 blkdev_get_block);
629}
630
631static int blkdev_write_end(struct file *file, struct address_space *mapping,
632 loff_t pos, unsigned len, unsigned copied,
633 struct page *page, void *fsdata)
634{
635 int ret;
636 ret = block_write_end(file, mapping, pos, len, copied, page, fsdata);
637
638 unlock_page(page);
639 put_page(page);
640
641 return ret;
642}
643
644/*
645 * private llseek:
646 * for a block special file file_inode(file)->i_size is zero
647 * so we compute the size by hand (just as in block_read/write above)
648 */
649static loff_t block_llseek(struct file *file, loff_t offset, int whence)
650{
651 struct inode *bd_inode = bdev_file_inode(file);
652 loff_t retval;
653
654 inode_lock(bd_inode);
655 retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode));
656 inode_unlock(bd_inode);
657 return retval;
658}
659
660int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
661{
662 struct inode *bd_inode = bdev_file_inode(filp);
663 struct block_device *bdev = I_BDEV(bd_inode);
664 int error;
665
666 error = file_write_and_wait_range(filp, start, end);
667 if (error)
668 return error;
669
670 /*
671 * There is no need to serialise calls to blkdev_issue_flush with
672 * i_mutex and doing so causes performance issues with concurrent
673 * O_SYNC writers to a block device.
674 */
675 error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL);
676 if (error == -EOPNOTSUPP)
677 error = 0;
678
679 return error;
680}
681EXPORT_SYMBOL(blkdev_fsync);
682
683/**
684 * bdev_read_page() - Start reading a page from a block device
685 * @bdev: The device to read the page from
686 * @sector: The offset on the device to read the page to (need not be aligned)
687 * @page: The page to read
688 *
689 * On entry, the page should be locked. It will be unlocked when the page
690 * has been read. If the block driver implements rw_page synchronously,
691 * that will be true on exit from this function, but it need not be.
692 *
693 * Errors returned by this function are usually "soft", eg out of memory, or
694 * queue full; callers should try a different route to read this page rather
695 * than propagate an error back up the stack.
696 *
697 * Return: negative errno if an error occurs, 0 if submission was successful.
698 */
699int bdev_read_page(struct block_device *bdev, sector_t sector,
700 struct page *page)
701{
702 const struct block_device_operations *ops = bdev->bd_disk->fops;
703 int result = -EOPNOTSUPP;
704
705 if (!ops->rw_page || bdev_get_integrity(bdev))
706 return result;
707
708 result = blk_queue_enter(bdev->bd_queue, 0);
709 if (result)
710 return result;
711 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
712 REQ_OP_READ);
713 blk_queue_exit(bdev->bd_queue);
714 return result;
715}
716EXPORT_SYMBOL_GPL(bdev_read_page);
717
718/**
719 * bdev_write_page() - Start writing a page to a block device
720 * @bdev: The device to write the page to
721 * @sector: The offset on the device to write the page to (need not be aligned)
722 * @page: The page to write
723 * @wbc: The writeback_control for the write
724 *
725 * On entry, the page should be locked and not currently under writeback.
726 * On exit, if the write started successfully, the page will be unlocked and
727 * under writeback. If the write failed already (eg the driver failed to
728 * queue the page to the device), the page will still be locked. If the
729 * caller is a ->writepage implementation, it will need to unlock the page.
730 *
731 * Errors returned by this function are usually "soft", eg out of memory, or
732 * queue full; callers should try a different route to write this page rather
733 * than propagate an error back up the stack.
734 *
735 * Return: negative errno if an error occurs, 0 if submission was successful.
736 */
737int bdev_write_page(struct block_device *bdev, sector_t sector,
738 struct page *page, struct writeback_control *wbc)
739{
740 int result;
741 const struct block_device_operations *ops = bdev->bd_disk->fops;
742
743 if (!ops->rw_page || bdev_get_integrity(bdev))
744 return -EOPNOTSUPP;
745 result = blk_queue_enter(bdev->bd_queue, 0);
746 if (result)
747 return result;
748
749 set_page_writeback(page);
750 result = ops->rw_page(bdev, sector + get_start_sect(bdev), page,
751 REQ_OP_WRITE);
752 if (result) {
753 end_page_writeback(page);
754 } else {
755 clean_page_buffers(page);
756 unlock_page(page);
757 }
758 blk_queue_exit(bdev->bd_queue);
759 return result;
760}
761EXPORT_SYMBOL_GPL(bdev_write_page);
762
763/*
764 * pseudo-fs
765 */
766
767static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock);
768static struct kmem_cache * bdev_cachep __read_mostly;
769
770static struct inode *bdev_alloc_inode(struct super_block *sb)
771{
772 struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL);
773 if (!ei)
774 return NULL;
775 return &ei->vfs_inode;
776}
777
778static void bdev_free_inode(struct inode *inode)
779{
780 kmem_cache_free(bdev_cachep, BDEV_I(inode));
781}
782
783static void init_once(void *foo)
784{
785 struct bdev_inode *ei = (struct bdev_inode *) foo;
786 struct block_device *bdev = &ei->bdev;
787
788 memset(bdev, 0, sizeof(*bdev));
789 mutex_init(&bdev->bd_mutex);
790 INIT_LIST_HEAD(&bdev->bd_list);
791#ifdef CONFIG_SYSFS
792 INIT_LIST_HEAD(&bdev->bd_holder_disks);
793#endif
794 bdev->bd_bdi = &noop_backing_dev_info;
795 inode_init_once(&ei->vfs_inode);
796 /* Initialize mutex for freeze. */
797 mutex_init(&bdev->bd_fsfreeze_mutex);
798}
799
800static void bdev_evict_inode(struct inode *inode)
801{
802 struct block_device *bdev = &BDEV_I(inode)->bdev;
803 truncate_inode_pages_final(&inode->i_data);
804 invalidate_inode_buffers(inode); /* is it needed here? */
805 clear_inode(inode);
806 spin_lock(&bdev_lock);
807 list_del_init(&bdev->bd_list);
808 spin_unlock(&bdev_lock);
809 /* Detach inode from wb early as bdi_put() may free bdi->wb */
810 inode_detach_wb(inode);
811 if (bdev->bd_bdi != &noop_backing_dev_info) {
812 bdi_put(bdev->bd_bdi);
813 bdev->bd_bdi = &noop_backing_dev_info;
814 }
815}
816
817static const struct super_operations bdev_sops = {
818 .statfs = simple_statfs,
819 .alloc_inode = bdev_alloc_inode,
820 .free_inode = bdev_free_inode,
821 .drop_inode = generic_delete_inode,
822 .evict_inode = bdev_evict_inode,
823};
824
825static int bd_init_fs_context(struct fs_context *fc)
826{
827 struct pseudo_fs_context *ctx = init_pseudo(fc, BDEVFS_MAGIC);
828 if (!ctx)
829 return -ENOMEM;
830 fc->s_iflags |= SB_I_CGROUPWB;
831 ctx->ops = &bdev_sops;
832 return 0;
833}
834
835static struct file_system_type bd_type = {
836 .name = "bdev",
837 .init_fs_context = bd_init_fs_context,
838 .kill_sb = kill_anon_super,
839};
840
841struct super_block *blockdev_superblock __read_mostly;
842EXPORT_SYMBOL_GPL(blockdev_superblock);
843
844void __init bdev_cache_init(void)
845{
846 int err;
847 static struct vfsmount *bd_mnt;
848
849 bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode),
850 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
851 SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC),
852 init_once);
853 err = register_filesystem(&bd_type);
854 if (err)
855 panic("Cannot register bdev pseudo-fs");
856 bd_mnt = kern_mount(&bd_type);
857 if (IS_ERR(bd_mnt))
858 panic("Cannot create bdev pseudo-fs");
859 blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */
860}
861
862/*
863 * Most likely _very_ bad one - but then it's hardly critical for small
864 * /dev and can be fixed when somebody will need really large one.
865 * Keep in mind that it will be fed through icache hash function too.
866 */
867static inline unsigned long hash(dev_t dev)
868{
869 return MAJOR(dev)+MINOR(dev);
870}
871
872static int bdev_test(struct inode *inode, void *data)
873{
874 return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data;
875}
876
877static int bdev_set(struct inode *inode, void *data)
878{
879 BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data;
880 return 0;
881}
882
883static LIST_HEAD(all_bdevs);
884
885/*
886 * If there is a bdev inode for this device, unhash it so that it gets evicted
887 * as soon as last inode reference is dropped.
888 */
889void bdev_unhash_inode(dev_t dev)
890{
891 struct inode *inode;
892
893 inode = ilookup5(blockdev_superblock, hash(dev), bdev_test, &dev);
894 if (inode) {
895 remove_inode_hash(inode);
896 iput(inode);
897 }
898}
899
900struct block_device *bdget(dev_t dev)
901{
902 struct block_device *bdev;
903 struct inode *inode;
904
905 inode = iget5_locked(blockdev_superblock, hash(dev),
906 bdev_test, bdev_set, &dev);
907
908 if (!inode)
909 return NULL;
910
911 bdev = &BDEV_I(inode)->bdev;
912
913 if (inode->i_state & I_NEW) {
914 bdev->bd_contains = NULL;
915 bdev->bd_super = NULL;
916 bdev->bd_inode = inode;
917 bdev->bd_block_size = i_blocksize(inode);
918 bdev->bd_part_count = 0;
919 bdev->bd_invalidated = 0;
920 inode->i_mode = S_IFBLK;
921 inode->i_rdev = dev;
922 inode->i_bdev = bdev;
923 inode->i_data.a_ops = &def_blk_aops;
924 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
925 spin_lock(&bdev_lock);
926 list_add(&bdev->bd_list, &all_bdevs);
927 spin_unlock(&bdev_lock);
928 unlock_new_inode(inode);
929 }
930 return bdev;
931}
932
933EXPORT_SYMBOL(bdget);
934
935/**
936 * bdgrab -- Grab a reference to an already referenced block device
937 * @bdev: Block device to grab a reference to.
938 */
939struct block_device *bdgrab(struct block_device *bdev)
940{
941 ihold(bdev->bd_inode);
942 return bdev;
943}
944EXPORT_SYMBOL(bdgrab);
945
946long nr_blockdev_pages(void)
947{
948 struct block_device *bdev;
949 long ret = 0;
950 spin_lock(&bdev_lock);
951 list_for_each_entry(bdev, &all_bdevs, bd_list) {
952 ret += bdev->bd_inode->i_mapping->nrpages;
953 }
954 spin_unlock(&bdev_lock);
955 return ret;
956}
957
958void bdput(struct block_device *bdev)
959{
960 iput(bdev->bd_inode);
961}
962
963EXPORT_SYMBOL(bdput);
964
965static struct block_device *bd_acquire(struct inode *inode)
966{
967 struct block_device *bdev;
968
969 spin_lock(&bdev_lock);
970 bdev = inode->i_bdev;
971 if (bdev && !inode_unhashed(bdev->bd_inode)) {
972 bdgrab(bdev);
973 spin_unlock(&bdev_lock);
974 return bdev;
975 }
976 spin_unlock(&bdev_lock);
977
978 /*
979 * i_bdev references block device inode that was already shut down
980 * (corresponding device got removed). Remove the reference and look
981 * up block device inode again just in case new device got
982 * reestablished under the same device number.
983 */
984 if (bdev)
985 bd_forget(inode);
986
987 bdev = bdget(inode->i_rdev);
988 if (bdev) {
989 spin_lock(&bdev_lock);
990 if (!inode->i_bdev) {
991 /*
992 * We take an additional reference to bd_inode,
993 * and it's released in clear_inode() of inode.
994 * So, we can access it via ->i_mapping always
995 * without igrab().
996 */
997 bdgrab(bdev);
998 inode->i_bdev = bdev;
999 inode->i_mapping = bdev->bd_inode->i_mapping;
1000 }
1001 spin_unlock(&bdev_lock);
1002 }
1003 return bdev;
1004}
1005
1006/* Call when you free inode */
1007
1008void bd_forget(struct inode *inode)
1009{
1010 struct block_device *bdev = NULL;
1011
1012 spin_lock(&bdev_lock);
1013 if (!sb_is_blkdev_sb(inode->i_sb))
1014 bdev = inode->i_bdev;
1015 inode->i_bdev = NULL;
1016 inode->i_mapping = &inode->i_data;
1017 spin_unlock(&bdev_lock);
1018
1019 if (bdev)
1020 bdput(bdev);
1021}
1022
1023/**
1024 * bd_may_claim - test whether a block device can be claimed
1025 * @bdev: block device of interest
1026 * @whole: whole block device containing @bdev, may equal @bdev
1027 * @holder: holder trying to claim @bdev
1028 *
1029 * Test whether @bdev can be claimed by @holder.
1030 *
1031 * CONTEXT:
1032 * spin_lock(&bdev_lock).
1033 *
1034 * RETURNS:
1035 * %true if @bdev can be claimed, %false otherwise.
1036 */
1037static bool bd_may_claim(struct block_device *bdev, struct block_device *whole,
1038 void *holder)
1039{
1040 if (bdev->bd_holder == holder)
1041 return true; /* already a holder */
1042 else if (bdev->bd_holder != NULL)
1043 return false; /* held by someone else */
1044 else if (whole == bdev)
1045 return true; /* is a whole device which isn't held */
1046
1047 else if (whole->bd_holder == bd_may_claim)
1048 return true; /* is a partition of a device that is being partitioned */
1049 else if (whole->bd_holder != NULL)
1050 return false; /* is a partition of a held device */
1051 else
1052 return true; /* is a partition of an un-held device */
1053}
1054
1055/**
1056 * bd_prepare_to_claim - prepare to claim a block device
1057 * @bdev: block device of interest
1058 * @whole: the whole device containing @bdev, may equal @bdev
1059 * @holder: holder trying to claim @bdev
1060 *
1061 * Prepare to claim @bdev. This function fails if @bdev is already
1062 * claimed by another holder and waits if another claiming is in
1063 * progress. This function doesn't actually claim. On successful
1064 * return, the caller has ownership of bd_claiming and bd_holder[s].
1065 *
1066 * CONTEXT:
1067 * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab
1068 * it multiple times.
1069 *
1070 * RETURNS:
1071 * 0 if @bdev can be claimed, -EBUSY otherwise.
1072 */
1073static int bd_prepare_to_claim(struct block_device *bdev,
1074 struct block_device *whole, void *holder)
1075{
1076retry:
1077 /* if someone else claimed, fail */
1078 if (!bd_may_claim(bdev, whole, holder))
1079 return -EBUSY;
1080
1081 /* if claiming is already in progress, wait for it to finish */
1082 if (whole->bd_claiming) {
1083 wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0);
1084 DEFINE_WAIT(wait);
1085
1086 prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
1087 spin_unlock(&bdev_lock);
1088 schedule();
1089 finish_wait(wq, &wait);
1090 spin_lock(&bdev_lock);
1091 goto retry;
1092 }
1093
1094 /* yay, all mine */
1095 return 0;
1096}
1097
1098static struct gendisk *bdev_get_gendisk(struct block_device *bdev, int *partno)
1099{
1100 struct gendisk *disk = get_gendisk(bdev->bd_dev, partno);
1101
1102 if (!disk)
1103 return NULL;
1104 /*
1105 * Now that we hold gendisk reference we make sure bdev we looked up is
1106 * not stale. If it is, it means device got removed and created before
1107 * we looked up gendisk and we fail open in such case. Associating
1108 * unhashed bdev with newly created gendisk could lead to two bdevs
1109 * (and thus two independent caches) being associated with one device
1110 * which is bad.
1111 */
1112 if (inode_unhashed(bdev->bd_inode)) {
1113 put_disk_and_module(disk);
1114 return NULL;
1115 }
1116 return disk;
1117}
1118
1119/**
1120 * bd_start_claiming - start claiming a block device
1121 * @bdev: block device of interest
1122 * @holder: holder trying to claim @bdev
1123 *
1124 * @bdev is about to be opened exclusively. Check @bdev can be opened
1125 * exclusively and mark that an exclusive open is in progress. Each
1126 * successful call to this function must be matched with a call to
1127 * either bd_finish_claiming() or bd_abort_claiming() (which do not
1128 * fail).
1129 *
1130 * This function is used to gain exclusive access to the block device
1131 * without actually causing other exclusive open attempts to fail. It
1132 * should be used when the open sequence itself requires exclusive
1133 * access but may subsequently fail.
1134 *
1135 * CONTEXT:
1136 * Might sleep.
1137 *
1138 * RETURNS:
1139 * Pointer to the block device containing @bdev on success, ERR_PTR()
1140 * value on failure.
1141 */
1142struct block_device *bd_start_claiming(struct block_device *bdev, void *holder)
1143{
1144 struct gendisk *disk;
1145 struct block_device *whole;
1146 int partno, err;
1147
1148 might_sleep();
1149
1150 /*
1151 * @bdev might not have been initialized properly yet, look up
1152 * and grab the outer block device the hard way.
1153 */
1154 disk = bdev_get_gendisk(bdev, &partno);
1155 if (!disk)
1156 return ERR_PTR(-ENXIO);
1157
1158 /*
1159 * Normally, @bdev should equal what's returned from bdget_disk()
1160 * if partno is 0; however, some drivers (floppy) use multiple
1161 * bdev's for the same physical device and @bdev may be one of the
1162 * aliases. Keep @bdev if partno is 0. This means claimer
1163 * tracking is broken for those devices but it has always been that
1164 * way.
1165 */
1166 if (partno)
1167 whole = bdget_disk(disk, 0);
1168 else
1169 whole = bdgrab(bdev);
1170
1171 put_disk_and_module(disk);
1172 if (!whole)
1173 return ERR_PTR(-ENOMEM);
1174
1175 /* prepare to claim, if successful, mark claiming in progress */
1176 spin_lock(&bdev_lock);
1177
1178 err = bd_prepare_to_claim(bdev, whole, holder);
1179 if (err == 0) {
1180 whole->bd_claiming = holder;
1181 spin_unlock(&bdev_lock);
1182 return whole;
1183 } else {
1184 spin_unlock(&bdev_lock);
1185 bdput(whole);
1186 return ERR_PTR(err);
1187 }
1188}
1189EXPORT_SYMBOL(bd_start_claiming);
1190
1191static void bd_clear_claiming(struct block_device *whole, void *holder)
1192{
1193 lockdep_assert_held(&bdev_lock);
1194 /* tell others that we're done */
1195 BUG_ON(whole->bd_claiming != holder);
1196 whole->bd_claiming = NULL;
1197 wake_up_bit(&whole->bd_claiming, 0);
1198}
1199
1200/**
1201 * bd_finish_claiming - finish claiming of a block device
1202 * @bdev: block device of interest
1203 * @whole: whole block device (returned from bd_start_claiming())
1204 * @holder: holder that has claimed @bdev
1205 *
1206 * Finish exclusive open of a block device. Mark the device as exlusively
1207 * open by the holder and wake up all waiters for exclusive open to finish.
1208 */
1209void bd_finish_claiming(struct block_device *bdev, struct block_device *whole,
1210 void *holder)
1211{
1212 spin_lock(&bdev_lock);
1213 BUG_ON(!bd_may_claim(bdev, whole, holder));
1214 /*
1215 * Note that for a whole device bd_holders will be incremented twice,
1216 * and bd_holder will be set to bd_may_claim before being set to holder
1217 */
1218 whole->bd_holders++;
1219 whole->bd_holder = bd_may_claim;
1220 bdev->bd_holders++;
1221 bdev->bd_holder = holder;
1222 bd_clear_claiming(whole, holder);
1223 spin_unlock(&bdev_lock);
1224}
1225EXPORT_SYMBOL(bd_finish_claiming);
1226
1227/**
1228 * bd_abort_claiming - abort claiming of a block device
1229 * @bdev: block device of interest
1230 * @whole: whole block device (returned from bd_start_claiming())
1231 * @holder: holder that has claimed @bdev
1232 *
1233 * Abort claiming of a block device when the exclusive open failed. This can be
1234 * also used when exclusive open is not actually desired and we just needed
1235 * to block other exclusive openers for a while.
1236 */
1237void bd_abort_claiming(struct block_device *bdev, struct block_device *whole,
1238 void *holder)
1239{
1240 spin_lock(&bdev_lock);
1241 bd_clear_claiming(whole, holder);
1242 spin_unlock(&bdev_lock);
1243}
1244EXPORT_SYMBOL(bd_abort_claiming);
1245
1246#ifdef CONFIG_SYSFS
1247struct bd_holder_disk {
1248 struct list_head list;
1249 struct gendisk *disk;
1250 int refcnt;
1251};
1252
1253static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev,
1254 struct gendisk *disk)
1255{
1256 struct bd_holder_disk *holder;
1257
1258 list_for_each_entry(holder, &bdev->bd_holder_disks, list)
1259 if (holder->disk == disk)
1260 return holder;
1261 return NULL;
1262}
1263
1264static int add_symlink(struct kobject *from, struct kobject *to)
1265{
1266 return sysfs_create_link(from, to, kobject_name(to));
1267}
1268
1269static void del_symlink(struct kobject *from, struct kobject *to)
1270{
1271 sysfs_remove_link(from, kobject_name(to));
1272}
1273
1274/**
1275 * bd_link_disk_holder - create symlinks between holding disk and slave bdev
1276 * @bdev: the claimed slave bdev
1277 * @disk: the holding disk
1278 *
1279 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1280 *
1281 * This functions creates the following sysfs symlinks.
1282 *
1283 * - from "slaves" directory of the holder @disk to the claimed @bdev
1284 * - from "holders" directory of the @bdev to the holder @disk
1285 *
1286 * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is
1287 * passed to bd_link_disk_holder(), then:
1288 *
1289 * /sys/block/dm-0/slaves/sda --> /sys/block/sda
1290 * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0
1291 *
1292 * The caller must have claimed @bdev before calling this function and
1293 * ensure that both @bdev and @disk are valid during the creation and
1294 * lifetime of these symlinks.
1295 *
1296 * CONTEXT:
1297 * Might sleep.
1298 *
1299 * RETURNS:
1300 * 0 on success, -errno on failure.
1301 */
1302int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk)
1303{
1304 struct bd_holder_disk *holder;
1305 int ret = 0;
1306
1307 mutex_lock(&bdev->bd_mutex);
1308
1309 WARN_ON_ONCE(!bdev->bd_holder);
1310
1311 /* FIXME: remove the following once add_disk() handles errors */
1312 if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir))
1313 goto out_unlock;
1314
1315 holder = bd_find_holder_disk(bdev, disk);
1316 if (holder) {
1317 holder->refcnt++;
1318 goto out_unlock;
1319 }
1320
1321 holder = kzalloc(sizeof(*holder), GFP_KERNEL);
1322 if (!holder) {
1323 ret = -ENOMEM;
1324 goto out_unlock;
1325 }
1326
1327 INIT_LIST_HEAD(&holder->list);
1328 holder->disk = disk;
1329 holder->refcnt = 1;
1330
1331 ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1332 if (ret)
1333 goto out_free;
1334
1335 ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj);
1336 if (ret)
1337 goto out_del;
1338 /*
1339 * bdev could be deleted beneath us which would implicitly destroy
1340 * the holder directory. Hold on to it.
1341 */
1342 kobject_get(bdev->bd_part->holder_dir);
1343
1344 list_add(&holder->list, &bdev->bd_holder_disks);
1345 goto out_unlock;
1346
1347out_del:
1348 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1349out_free:
1350 kfree(holder);
1351out_unlock:
1352 mutex_unlock(&bdev->bd_mutex);
1353 return ret;
1354}
1355EXPORT_SYMBOL_GPL(bd_link_disk_holder);
1356
1357/**
1358 * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder()
1359 * @bdev: the calimed slave bdev
1360 * @disk: the holding disk
1361 *
1362 * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT.
1363 *
1364 * CONTEXT:
1365 * Might sleep.
1366 */
1367void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk)
1368{
1369 struct bd_holder_disk *holder;
1370
1371 mutex_lock(&bdev->bd_mutex);
1372
1373 holder = bd_find_holder_disk(bdev, disk);
1374
1375 if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) {
1376 del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj);
1377 del_symlink(bdev->bd_part->holder_dir,
1378 &disk_to_dev(disk)->kobj);
1379 kobject_put(bdev->bd_part->holder_dir);
1380 list_del_init(&holder->list);
1381 kfree(holder);
1382 }
1383
1384 mutex_unlock(&bdev->bd_mutex);
1385}
1386EXPORT_SYMBOL_GPL(bd_unlink_disk_holder);
1387#endif
1388
1389/**
1390 * flush_disk - invalidates all buffer-cache entries on a disk
1391 *
1392 * @bdev: struct block device to be flushed
1393 * @kill_dirty: flag to guide handling of dirty inodes
1394 *
1395 * Invalidates all buffer-cache entries on a disk. It should be called
1396 * when a disk has been changed -- either by a media change or online
1397 * resize.
1398 */
1399static void flush_disk(struct block_device *bdev, bool kill_dirty)
1400{
1401 if (__invalidate_device(bdev, kill_dirty)) {
1402 printk(KERN_WARNING "VFS: busy inodes on changed media or "
1403 "resized disk %s\n",
1404 bdev->bd_disk ? bdev->bd_disk->disk_name : "");
1405 }
1406
1407 if (!bdev->bd_disk)
1408 return;
1409 if (disk_part_scan_enabled(bdev->bd_disk))
1410 bdev->bd_invalidated = 1;
1411}
1412
1413/**
1414 * check_disk_size_change - checks for disk size change and adjusts bdev size.
1415 * @disk: struct gendisk to check
1416 * @bdev: struct bdev to adjust.
1417 * @verbose: if %true log a message about a size change if there is any
1418 *
1419 * This routine checks to see if the bdev size does not match the disk size
1420 * and adjusts it if it differs. When shrinking the bdev size, its all caches
1421 * are freed.
1422 */
1423void check_disk_size_change(struct gendisk *disk, struct block_device *bdev,
1424 bool verbose)
1425{
1426 loff_t disk_size, bdev_size;
1427
1428 disk_size = (loff_t)get_capacity(disk) << 9;
1429 bdev_size = i_size_read(bdev->bd_inode);
1430 if (disk_size != bdev_size) {
1431 if (verbose) {
1432 printk(KERN_INFO
1433 "%s: detected capacity change from %lld to %lld\n",
1434 disk->disk_name, bdev_size, disk_size);
1435 }
1436 i_size_write(bdev->bd_inode, disk_size);
1437 if (bdev_size > disk_size)
1438 flush_disk(bdev, false);
1439 }
1440}
1441
1442/**
1443 * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back
1444 * @disk: struct gendisk to be revalidated
1445 *
1446 * This routine is a wrapper for lower-level driver's revalidate_disk
1447 * call-backs. It is used to do common pre and post operations needed
1448 * for all revalidate_disk operations.
1449 */
1450int revalidate_disk(struct gendisk *disk)
1451{
1452 int ret = 0;
1453
1454 if (disk->fops->revalidate_disk)
1455 ret = disk->fops->revalidate_disk(disk);
1456
1457 /*
1458 * Hidden disks don't have associated bdev so there's no point in
1459 * revalidating it.
1460 */
1461 if (!(disk->flags & GENHD_FL_HIDDEN)) {
1462 struct block_device *bdev = bdget_disk(disk, 0);
1463
1464 if (!bdev)
1465 return ret;
1466
1467 mutex_lock(&bdev->bd_mutex);
1468 check_disk_size_change(disk, bdev, ret == 0);
1469 bdev->bd_invalidated = 0;
1470 mutex_unlock(&bdev->bd_mutex);
1471 bdput(bdev);
1472 }
1473 return ret;
1474}
1475EXPORT_SYMBOL(revalidate_disk);
1476
1477/*
1478 * This routine checks whether a removable media has been changed,
1479 * and invalidates all buffer-cache-entries in that case. This
1480 * is a relatively slow routine, so we have to try to minimize using
1481 * it. Thus it is called only upon a 'mount' or 'open'. This
1482 * is the best way of combining speed and utility, I think.
1483 * People changing diskettes in the middle of an operation deserve
1484 * to lose :-)
1485 */
1486int check_disk_change(struct block_device *bdev)
1487{
1488 struct gendisk *disk = bdev->bd_disk;
1489 const struct block_device_operations *bdops = disk->fops;
1490 unsigned int events;
1491
1492 events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE |
1493 DISK_EVENT_EJECT_REQUEST);
1494 if (!(events & DISK_EVENT_MEDIA_CHANGE))
1495 return 0;
1496
1497 flush_disk(bdev, true);
1498 if (bdops->revalidate_disk)
1499 bdops->revalidate_disk(bdev->bd_disk);
1500 return 1;
1501}
1502
1503EXPORT_SYMBOL(check_disk_change);
1504
1505void bd_set_size(struct block_device *bdev, loff_t size)
1506{
1507 inode_lock(bdev->bd_inode);
1508 i_size_write(bdev->bd_inode, size);
1509 inode_unlock(bdev->bd_inode);
1510}
1511EXPORT_SYMBOL(bd_set_size);
1512
1513static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part);
1514
1515/*
1516 * bd_mutex locking:
1517 *
1518 * mutex_lock(part->bd_mutex)
1519 * mutex_lock_nested(whole->bd_mutex, 1)
1520 */
1521
1522static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
1523{
1524 struct gendisk *disk;
1525 int ret;
1526 int partno;
1527 int perm = 0;
1528 bool first_open = false;
1529
1530 if (mode & FMODE_READ)
1531 perm |= MAY_READ;
1532 if (mode & FMODE_WRITE)
1533 perm |= MAY_WRITE;
1534 /*
1535 * hooks: /n/, see "layering violations".
1536 */
1537 if (!for_part) {
1538 ret = devcgroup_inode_permission(bdev->bd_inode, perm);
1539 if (ret != 0) {
1540 bdput(bdev);
1541 return ret;
1542 }
1543 }
1544
1545 restart:
1546
1547 ret = -ENXIO;
1548 disk = bdev_get_gendisk(bdev, &partno);
1549 if (!disk)
1550 goto out;
1551
1552 disk_block_events(disk);
1553 mutex_lock_nested(&bdev->bd_mutex, for_part);
1554 if (!bdev->bd_openers) {
1555 first_open = true;
1556 bdev->bd_disk = disk;
1557 bdev->bd_queue = disk->queue;
1558 bdev->bd_contains = bdev;
1559 bdev->bd_partno = partno;
1560
1561 if (!partno) {
1562 ret = -ENXIO;
1563 bdev->bd_part = disk_get_part(disk, partno);
1564 if (!bdev->bd_part)
1565 goto out_clear;
1566
1567 ret = 0;
1568 if (disk->fops->open) {
1569 ret = disk->fops->open(bdev, mode);
1570 if (ret == -ERESTARTSYS) {
1571 /* Lost a race with 'disk' being
1572 * deleted, try again.
1573 * See md.c
1574 */
1575 disk_put_part(bdev->bd_part);
1576 bdev->bd_part = NULL;
1577 bdev->bd_disk = NULL;
1578 bdev->bd_queue = NULL;
1579 mutex_unlock(&bdev->bd_mutex);
1580 disk_unblock_events(disk);
1581 put_disk_and_module(disk);
1582 goto restart;
1583 }
1584 }
1585
1586 if (!ret) {
1587 bd_set_size(bdev,(loff_t)get_capacity(disk)<<9);
1588 set_init_blocksize(bdev);
1589 }
1590
1591 /*
1592 * If the device is invalidated, rescan partition
1593 * if open succeeded or failed with -ENOMEDIUM.
1594 * The latter is necessary to prevent ghost
1595 * partitions on a removed medium.
1596 */
1597 if (bdev->bd_invalidated) {
1598 if (!ret)
1599 rescan_partitions(disk, bdev);
1600 else if (ret == -ENOMEDIUM)
1601 invalidate_partitions(disk, bdev);
1602 }
1603
1604 if (ret)
1605 goto out_clear;
1606 } else {
1607 struct block_device *whole;
1608 whole = bdget_disk(disk, 0);
1609 ret = -ENOMEM;
1610 if (!whole)
1611 goto out_clear;
1612 BUG_ON(for_part);
1613 ret = __blkdev_get(whole, mode, 1);
1614 if (ret)
1615 goto out_clear;
1616 bdev->bd_contains = whole;
1617 bdev->bd_part = disk_get_part(disk, partno);
1618 if (!(disk->flags & GENHD_FL_UP) ||
1619 !bdev->bd_part || !bdev->bd_part->nr_sects) {
1620 ret = -ENXIO;
1621 goto out_clear;
1622 }
1623 bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9);
1624 set_init_blocksize(bdev);
1625 }
1626
1627 if (bdev->bd_bdi == &noop_backing_dev_info)
1628 bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info);
1629 } else {
1630 if (bdev->bd_contains == bdev) {
1631 ret = 0;
1632 if (bdev->bd_disk->fops->open)
1633 ret = bdev->bd_disk->fops->open(bdev, mode);
1634 /* the same as first opener case, read comment there */
1635 if (bdev->bd_invalidated) {
1636 if (!ret)
1637 rescan_partitions(bdev->bd_disk, bdev);
1638 else if (ret == -ENOMEDIUM)
1639 invalidate_partitions(bdev->bd_disk, bdev);
1640 }
1641 if (ret)
1642 goto out_unlock_bdev;
1643 }
1644 }
1645 bdev->bd_openers++;
1646 if (for_part)
1647 bdev->bd_part_count++;
1648 mutex_unlock(&bdev->bd_mutex);
1649 disk_unblock_events(disk);
1650 /* only one opener holds refs to the module and disk */
1651 if (!first_open)
1652 put_disk_and_module(disk);
1653 return 0;
1654
1655 out_clear:
1656 disk_put_part(bdev->bd_part);
1657 bdev->bd_disk = NULL;
1658 bdev->bd_part = NULL;
1659 bdev->bd_queue = NULL;
1660 if (bdev != bdev->bd_contains)
1661 __blkdev_put(bdev->bd_contains, mode, 1);
1662 bdev->bd_contains = NULL;
1663 out_unlock_bdev:
1664 mutex_unlock(&bdev->bd_mutex);
1665 disk_unblock_events(disk);
1666 put_disk_and_module(disk);
1667 out:
1668 bdput(bdev);
1669
1670 return ret;
1671}
1672
1673/**
1674 * blkdev_get - open a block device
1675 * @bdev: block_device to open
1676 * @mode: FMODE_* mask
1677 * @holder: exclusive holder identifier
1678 *
1679 * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is
1680 * open with exclusive access. Specifying %FMODE_EXCL with %NULL
1681 * @holder is invalid. Exclusive opens may nest for the same @holder.
1682 *
1683 * On success, the reference count of @bdev is unchanged. On failure,
1684 * @bdev is put.
1685 *
1686 * CONTEXT:
1687 * Might sleep.
1688 *
1689 * RETURNS:
1690 * 0 on success, -errno on failure.
1691 */
1692int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
1693{
1694 struct block_device *whole = NULL;
1695 int res;
1696
1697 WARN_ON_ONCE((mode & FMODE_EXCL) && !holder);
1698
1699 if ((mode & FMODE_EXCL) && holder) {
1700 whole = bd_start_claiming(bdev, holder);
1701 if (IS_ERR(whole)) {
1702 bdput(bdev);
1703 return PTR_ERR(whole);
1704 }
1705 }
1706
1707 res = __blkdev_get(bdev, mode, 0);
1708
1709 if (whole) {
1710 struct gendisk *disk = whole->bd_disk;
1711
1712 /* finish claiming */
1713 mutex_lock(&bdev->bd_mutex);
1714 if (!res)
1715 bd_finish_claiming(bdev, whole, holder);
1716 else
1717 bd_abort_claiming(bdev, whole, holder);
1718 /*
1719 * Block event polling for write claims if requested. Any
1720 * write holder makes the write_holder state stick until
1721 * all are released. This is good enough and tracking
1722 * individual writeable reference is too fragile given the
1723 * way @mode is used in blkdev_get/put().
1724 */
1725 if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder &&
1726 (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) {
1727 bdev->bd_write_holder = true;
1728 disk_block_events(disk);
1729 }
1730
1731 mutex_unlock(&bdev->bd_mutex);
1732 bdput(whole);
1733 }
1734
1735 return res;
1736}
1737EXPORT_SYMBOL(blkdev_get);
1738
1739/**
1740 * blkdev_get_by_path - open a block device by name
1741 * @path: path to the block device to open
1742 * @mode: FMODE_* mask
1743 * @holder: exclusive holder identifier
1744 *
1745 * Open the blockdevice described by the device file at @path. @mode
1746 * and @holder are identical to blkdev_get().
1747 *
1748 * On success, the returned block_device has reference count of one.
1749 *
1750 * CONTEXT:
1751 * Might sleep.
1752 *
1753 * RETURNS:
1754 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1755 */
1756struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
1757 void *holder)
1758{
1759 struct block_device *bdev;
1760 int err;
1761
1762 bdev = lookup_bdev(path);
1763 if (IS_ERR(bdev))
1764 return bdev;
1765
1766 err = blkdev_get(bdev, mode, holder);
1767 if (err)
1768 return ERR_PTR(err);
1769
1770 if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) {
1771 blkdev_put(bdev, mode);
1772 return ERR_PTR(-EACCES);
1773 }
1774
1775 return bdev;
1776}
1777EXPORT_SYMBOL(blkdev_get_by_path);
1778
1779/**
1780 * blkdev_get_by_dev - open a block device by device number
1781 * @dev: device number of block device to open
1782 * @mode: FMODE_* mask
1783 * @holder: exclusive holder identifier
1784 *
1785 * Open the blockdevice described by device number @dev. @mode and
1786 * @holder are identical to blkdev_get().
1787 *
1788 * Use it ONLY if you really do not have anything better - i.e. when
1789 * you are behind a truly sucky interface and all you are given is a
1790 * device number. _Never_ to be used for internal purposes. If you
1791 * ever need it - reconsider your API.
1792 *
1793 * On success, the returned block_device has reference count of one.
1794 *
1795 * CONTEXT:
1796 * Might sleep.
1797 *
1798 * RETURNS:
1799 * Pointer to block_device on success, ERR_PTR(-errno) on failure.
1800 */
1801struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder)
1802{
1803 struct block_device *bdev;
1804 int err;
1805
1806 bdev = bdget(dev);
1807 if (!bdev)
1808 return ERR_PTR(-ENOMEM);
1809
1810 err = blkdev_get(bdev, mode, holder);
1811 if (err)
1812 return ERR_PTR(err);
1813
1814 return bdev;
1815}
1816EXPORT_SYMBOL(blkdev_get_by_dev);
1817
1818static int blkdev_open(struct inode * inode, struct file * filp)
1819{
1820 struct block_device *bdev;
1821
1822 /*
1823 * Preserve backwards compatibility and allow large file access
1824 * even if userspace doesn't ask for it explicitly. Some mkfs
1825 * binary needs it. We might want to drop this workaround
1826 * during an unstable branch.
1827 */
1828 filp->f_flags |= O_LARGEFILE;
1829
1830 filp->f_mode |= FMODE_NOWAIT;
1831
1832 if (filp->f_flags & O_NDELAY)
1833 filp->f_mode |= FMODE_NDELAY;
1834 if (filp->f_flags & O_EXCL)
1835 filp->f_mode |= FMODE_EXCL;
1836 if ((filp->f_flags & O_ACCMODE) == 3)
1837 filp->f_mode |= FMODE_WRITE_IOCTL;
1838
1839 bdev = bd_acquire(inode);
1840 if (bdev == NULL)
1841 return -ENOMEM;
1842
1843 filp->f_mapping = bdev->bd_inode->i_mapping;
1844 filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
1845
1846 return blkdev_get(bdev, filp->f_mode, filp);
1847}
1848
1849static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part)
1850{
1851 struct gendisk *disk = bdev->bd_disk;
1852 struct block_device *victim = NULL;
1853
1854 mutex_lock_nested(&bdev->bd_mutex, for_part);
1855 if (for_part)
1856 bdev->bd_part_count--;
1857
1858 if (!--bdev->bd_openers) {
1859 WARN_ON_ONCE(bdev->bd_holders);
1860 sync_blockdev(bdev);
1861 kill_bdev(bdev);
1862
1863 bdev_write_inode(bdev);
1864 }
1865 if (bdev->bd_contains == bdev) {
1866 if (disk->fops->release)
1867 disk->fops->release(disk, mode);
1868 }
1869 if (!bdev->bd_openers) {
1870 disk_put_part(bdev->bd_part);
1871 bdev->bd_part = NULL;
1872 bdev->bd_disk = NULL;
1873 if (bdev != bdev->bd_contains)
1874 victim = bdev->bd_contains;
1875 bdev->bd_contains = NULL;
1876
1877 put_disk_and_module(disk);
1878 }
1879 mutex_unlock(&bdev->bd_mutex);
1880 bdput(bdev);
1881 if (victim)
1882 __blkdev_put(victim, mode, 1);
1883}
1884
1885void blkdev_put(struct block_device *bdev, fmode_t mode)
1886{
1887 mutex_lock(&bdev->bd_mutex);
1888
1889 if (mode & FMODE_EXCL) {
1890 bool bdev_free;
1891
1892 /*
1893 * Release a claim on the device. The holder fields
1894 * are protected with bdev_lock. bd_mutex is to
1895 * synchronize disk_holder unlinking.
1896 */
1897 spin_lock(&bdev_lock);
1898
1899 WARN_ON_ONCE(--bdev->bd_holders < 0);
1900 WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0);
1901
1902 /* bd_contains might point to self, check in a separate step */
1903 if ((bdev_free = !bdev->bd_holders))
1904 bdev->bd_holder = NULL;
1905 if (!bdev->bd_contains->bd_holders)
1906 bdev->bd_contains->bd_holder = NULL;
1907
1908 spin_unlock(&bdev_lock);
1909
1910 /*
1911 * If this was the last claim, remove holder link and
1912 * unblock evpoll if it was a write holder.
1913 */
1914 if (bdev_free && bdev->bd_write_holder) {
1915 disk_unblock_events(bdev->bd_disk);
1916 bdev->bd_write_holder = false;
1917 }
1918 }
1919
1920 /*
1921 * Trigger event checking and tell drivers to flush MEDIA_CHANGE
1922 * event. This is to ensure detection of media removal commanded
1923 * from userland - e.g. eject(1).
1924 */
1925 disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE);
1926
1927 mutex_unlock(&bdev->bd_mutex);
1928
1929 __blkdev_put(bdev, mode, 0);
1930}
1931EXPORT_SYMBOL(blkdev_put);
1932
1933static int blkdev_close(struct inode * inode, struct file * filp)
1934{
1935 struct block_device *bdev = I_BDEV(bdev_file_inode(filp));
1936 blkdev_put(bdev, filp->f_mode);
1937 return 0;
1938}
1939
1940static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg)
1941{
1942 struct block_device *bdev = I_BDEV(bdev_file_inode(file));
1943 fmode_t mode = file->f_mode;
1944
1945 /*
1946 * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have
1947 * to updated it before every ioctl.
1948 */
1949 if (file->f_flags & O_NDELAY)
1950 mode |= FMODE_NDELAY;
1951 else
1952 mode &= ~FMODE_NDELAY;
1953
1954 return blkdev_ioctl(bdev, mode, cmd, arg);
1955}
1956
1957/*
1958 * Write data to the block device. Only intended for the block device itself
1959 * and the raw driver which basically is a fake block device.
1960 *
1961 * Does not take i_mutex for the write and thus is not for general purpose
1962 * use.
1963 */
1964ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from)
1965{
1966 struct file *file = iocb->ki_filp;
1967 struct inode *bd_inode = bdev_file_inode(file);
1968 loff_t size = i_size_read(bd_inode);
1969 struct blk_plug plug;
1970 ssize_t ret;
1971
1972 if (bdev_read_only(I_BDEV(bd_inode)))
1973 return -EPERM;
1974
1975 if (IS_SWAPFILE(bd_inode))
1976 return -ETXTBSY;
1977
1978 if (!iov_iter_count(from))
1979 return 0;
1980
1981 if (iocb->ki_pos >= size)
1982 return -ENOSPC;
1983
1984 if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
1985 return -EOPNOTSUPP;
1986
1987 iov_iter_truncate(from, size - iocb->ki_pos);
1988
1989 blk_start_plug(&plug);
1990 ret = __generic_file_write_iter(iocb, from);
1991 if (ret > 0)
1992 ret = generic_write_sync(iocb, ret);
1993 blk_finish_plug(&plug);
1994 return ret;
1995}
1996EXPORT_SYMBOL_GPL(blkdev_write_iter);
1997
1998ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to)
1999{
2000 struct file *file = iocb->ki_filp;
2001 struct inode *bd_inode = bdev_file_inode(file);
2002 loff_t size = i_size_read(bd_inode);
2003 loff_t pos = iocb->ki_pos;
2004
2005 if (pos >= size)
2006 return 0;
2007
2008 size -= pos;
2009 iov_iter_truncate(to, size);
2010 return generic_file_read_iter(iocb, to);
2011}
2012EXPORT_SYMBOL_GPL(blkdev_read_iter);
2013
2014/*
2015 * Try to release a page associated with block device when the system
2016 * is under memory pressure.
2017 */
2018static int blkdev_releasepage(struct page *page, gfp_t wait)
2019{
2020 struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super;
2021
2022 if (super && super->s_op->bdev_try_to_free_page)
2023 return super->s_op->bdev_try_to_free_page(super, page, wait);
2024
2025 return try_to_free_buffers(page);
2026}
2027
2028static int blkdev_writepages(struct address_space *mapping,
2029 struct writeback_control *wbc)
2030{
2031 return generic_writepages(mapping, wbc);
2032}
2033
2034static const struct address_space_operations def_blk_aops = {
2035 .readpage = blkdev_readpage,
2036 .readpages = blkdev_readpages,
2037 .writepage = blkdev_writepage,
2038 .write_begin = blkdev_write_begin,
2039 .write_end = blkdev_write_end,
2040 .writepages = blkdev_writepages,
2041 .releasepage = blkdev_releasepage,
2042 .direct_IO = blkdev_direct_IO,
2043 .migratepage = buffer_migrate_page_norefs,
2044 .is_dirty_writeback = buffer_check_dirty_writeback,
2045};
2046
2047#define BLKDEV_FALLOC_FL_SUPPORTED \
2048 (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \
2049 FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE)
2050
2051static long blkdev_fallocate(struct file *file, int mode, loff_t start,
2052 loff_t len)
2053{
2054 struct block_device *bdev = I_BDEV(bdev_file_inode(file));
2055 struct address_space *mapping;
2056 loff_t end = start + len - 1;
2057 loff_t isize;
2058 int error;
2059
2060 /* Fail if we don't recognize the flags. */
2061 if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED)
2062 return -EOPNOTSUPP;
2063
2064 /* Don't go off the end of the device. */
2065 isize = i_size_read(bdev->bd_inode);
2066 if (start >= isize)
2067 return -EINVAL;
2068 if (end >= isize) {
2069 if (mode & FALLOC_FL_KEEP_SIZE) {
2070 len = isize - start;
2071 end = start + len - 1;
2072 } else
2073 return -EINVAL;
2074 }
2075
2076 /*
2077 * Don't allow IO that isn't aligned to logical block size.
2078 */
2079 if ((start | len) & (bdev_logical_block_size(bdev) - 1))
2080 return -EINVAL;
2081
2082 /* Invalidate the page cache, including dirty pages. */
2083 mapping = bdev->bd_inode->i_mapping;
2084 truncate_inode_pages_range(mapping, start, end);
2085
2086 switch (mode) {
2087 case FALLOC_FL_ZERO_RANGE:
2088 case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE:
2089 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
2090 GFP_KERNEL, BLKDEV_ZERO_NOUNMAP);
2091 break;
2092 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE:
2093 error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9,
2094 GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK);
2095 break;
2096 case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE:
2097 error = blkdev_issue_discard(bdev, start >> 9, len >> 9,
2098 GFP_KERNEL, 0);
2099 break;
2100 default:
2101 return -EOPNOTSUPP;
2102 }
2103 if (error)
2104 return error;
2105
2106 /*
2107 * Invalidate again; if someone wandered in and dirtied a page,
2108 * the caller will be given -EBUSY. The third argument is
2109 * inclusive, so the rounding here is safe.
2110 */
2111 return invalidate_inode_pages2_range(mapping,
2112 start >> PAGE_SHIFT,
2113 end >> PAGE_SHIFT);
2114}
2115
2116const struct file_operations def_blk_fops = {
2117 .open = blkdev_open,
2118 .release = blkdev_close,
2119 .llseek = block_llseek,
2120 .read_iter = blkdev_read_iter,
2121 .write_iter = blkdev_write_iter,
2122 .iopoll = blkdev_iopoll,
2123 .mmap = generic_file_mmap,
2124 .fsync = blkdev_fsync,
2125 .unlocked_ioctl = block_ioctl,
2126#ifdef CONFIG_COMPAT
2127 .compat_ioctl = compat_blkdev_ioctl,
2128#endif
2129 .splice_read = generic_file_splice_read,
2130 .splice_write = iter_file_splice_write,
2131 .fallocate = blkdev_fallocate,
2132};
2133
2134int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg)
2135{
2136 int res;
2137 mm_segment_t old_fs = get_fs();
2138 set_fs(KERNEL_DS);
2139 res = blkdev_ioctl(bdev, 0, cmd, arg);
2140 set_fs(old_fs);
2141 return res;
2142}
2143
2144EXPORT_SYMBOL(ioctl_by_bdev);
2145
2146/**
2147 * lookup_bdev - lookup a struct block_device by name
2148 * @pathname: special file representing the block device
2149 *
2150 * Get a reference to the blockdevice at @pathname in the current
2151 * namespace if possible and return it. Return ERR_PTR(error)
2152 * otherwise.
2153 */
2154struct block_device *lookup_bdev(const char *pathname)
2155{
2156 struct block_device *bdev;
2157 struct inode *inode;
2158 struct path path;
2159 int error;
2160
2161 if (!pathname || !*pathname)
2162 return ERR_PTR(-EINVAL);
2163
2164 error = kern_path(pathname, LOOKUP_FOLLOW, &path);
2165 if (error)
2166 return ERR_PTR(error);
2167
2168 inode = d_backing_inode(path.dentry);
2169 error = -ENOTBLK;
2170 if (!S_ISBLK(inode->i_mode))
2171 goto fail;
2172 error = -EACCES;
2173 if (!may_open_dev(&path))
2174 goto fail;
2175 error = -ENOMEM;
2176 bdev = bd_acquire(inode);
2177 if (!bdev)
2178 goto fail;
2179out:
2180 path_put(&path);
2181 return bdev;
2182fail:
2183 bdev = ERR_PTR(error);
2184 goto out;
2185}
2186EXPORT_SYMBOL(lookup_bdev);
2187
2188int __invalidate_device(struct block_device *bdev, bool kill_dirty)
2189{
2190 struct super_block *sb = get_super(bdev);
2191 int res = 0;
2192
2193 if (sb) {
2194 /*
2195 * no need to lock the super, get_super holds the
2196 * read mutex so the filesystem cannot go away
2197 * under us (->put_super runs with the write lock
2198 * hold).
2199 */
2200 shrink_dcache_sb(sb);
2201 res = invalidate_inodes(sb, kill_dirty);
2202 drop_super(sb);
2203 }
2204 invalidate_bdev(bdev);
2205 return res;
2206}
2207EXPORT_SYMBOL(__invalidate_device);
2208
2209void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg)
2210{
2211 struct inode *inode, *old_inode = NULL;
2212
2213 spin_lock(&blockdev_superblock->s_inode_list_lock);
2214 list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) {
2215 struct address_space *mapping = inode->i_mapping;
2216 struct block_device *bdev;
2217
2218 spin_lock(&inode->i_lock);
2219 if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) ||
2220 mapping->nrpages == 0) {
2221 spin_unlock(&inode->i_lock);
2222 continue;
2223 }
2224 __iget(inode);
2225 spin_unlock(&inode->i_lock);
2226 spin_unlock(&blockdev_superblock->s_inode_list_lock);
2227 /*
2228 * We hold a reference to 'inode' so it couldn't have been
2229 * removed from s_inodes list while we dropped the
2230 * s_inode_list_lock We cannot iput the inode now as we can
2231 * be holding the last reference and we cannot iput it under
2232 * s_inode_list_lock. So we keep the reference and iput it
2233 * later.
2234 */
2235 iput(old_inode);
2236 old_inode = inode;
2237 bdev = I_BDEV(inode);
2238
2239 mutex_lock(&bdev->bd_mutex);
2240 if (bdev->bd_openers)
2241 func(bdev, arg);
2242 mutex_unlock(&bdev->bd_mutex);
2243
2244 spin_lock(&blockdev_superblock->s_inode_list_lock);
2245 }
2246 spin_unlock(&blockdev_superblock->s_inode_list_lock);
2247 iput(old_inode);
2248}