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