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