projects/linux·blob v4.9-rc3 · refs

1980 lines · 49.7 KiB

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