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1 | /* |
2 | * linux/fs/block_dev.c |
3 | * |
4 | * Copyright (C) 1991, 1992 Linus Torvalds |
5 | * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE |
6 | */ |
7 | |
8 | #include <linux/init.h> |
9 | #include <linux/mm.h> |
10 | #include <linux/fcntl.h> |
11 | #include <linux/slab.h> |
12 | #include <linux/kmod.h> |
13 | #include <linux/major.h> |
14 | #include <linux/device_cgroup.h> |
15 | #include <linux/highmem.h> |
16 | #include <linux/blkdev.h> |
17 | #include <linux/module.h> |
18 | #include <linux/blkpg.h> |
19 | #include <linux/magic.h> |
20 | #include <linux/buffer_head.h> |
21 | #include <linux/swap.h> |
22 | #include <linux/pagevec.h> |
23 | #include <linux/writeback.h> |
24 | #include <linux/mpage.h> |
25 | #include <linux/mount.h> |
26 | #include <linux/uio.h> |
27 | #include <linux/namei.h> |
28 | #include <linux/log2.h> |
29 | #include <linux/cleancache.h> |
30 | #include <linux/aio.h> |
31 | #include <asm/uaccess.h> |
32 | #include "internal.h" |
33 | |
34 | struct bdev_inode { |
35 | struct block_device bdev; |
36 | struct inode vfs_inode; |
37 | }; |
38 | |
39 | static const struct address_space_operations def_blk_aops; |
40 | |
41 | static inline struct bdev_inode *BDEV_I(struct inode *inode) |
42 | { |
43 | return container_of(inode, struct bdev_inode, vfs_inode); |
44 | } |
45 | |
46 | inline struct block_device *I_BDEV(struct inode *inode) |
47 | { |
48 | return &BDEV_I(inode)->bdev; |
49 | } |
50 | EXPORT_SYMBOL(I_BDEV); |
51 | |
52 | /* |
53 | * Move the inode from its current bdi to a new bdi. If the inode is dirty we |
54 | * need to move it onto the dirty list of @dst so that the inode is always on |
55 | * the right list. |
56 | */ |
57 | static void bdev_inode_switch_bdi(struct inode *inode, |
58 | struct backing_dev_info *dst) |
59 | { |
60 | struct backing_dev_info *old = inode->i_data.backing_dev_info; |
61 | bool wakeup_bdi = false; |
62 | |
63 | if (unlikely(dst == old)) /* deadlock avoidance */ |
64 | return; |
65 | bdi_lock_two(&old->wb, &dst->wb); |
66 | spin_lock(&inode->i_lock); |
67 | inode->i_data.backing_dev_info = dst; |
68 | if (inode->i_state & I_DIRTY) { |
69 | if (bdi_cap_writeback_dirty(dst) && !wb_has_dirty_io(&dst->wb)) |
70 | wakeup_bdi = true; |
71 | list_move(&inode->i_wb_list, &dst->wb.b_dirty); |
72 | } |
73 | spin_unlock(&inode->i_lock); |
74 | spin_unlock(&old->wb.list_lock); |
75 | spin_unlock(&dst->wb.list_lock); |
76 | |
77 | if (wakeup_bdi) |
78 | bdi_wakeup_thread_delayed(dst); |
79 | } |
80 | |
81 | /* Kill _all_ buffers and pagecache , dirty or not.. */ |
82 | void kill_bdev(struct block_device *bdev) |
83 | { |
84 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
85 | |
86 | if (mapping->nrpages == 0 && mapping->nrshadows == 0) |
87 | return; |
88 | |
89 | invalidate_bh_lrus(); |
90 | truncate_inode_pages(mapping, 0); |
91 | } |
92 | EXPORT_SYMBOL(kill_bdev); |
93 | |
94 | /* Invalidate clean unused buffers and pagecache. */ |
95 | void invalidate_bdev(struct block_device *bdev) |
96 | { |
97 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
98 | |
99 | if (mapping->nrpages == 0) |
100 | return; |
101 | |
102 | invalidate_bh_lrus(); |
103 | lru_add_drain_all(); /* make sure all lru add caches are flushed */ |
104 | invalidate_mapping_pages(mapping, 0, -1); |
105 | /* 99% of the time, we don't need to flush the cleancache on the bdev. |
106 | * But, for the strange corners, lets be cautious |
107 | */ |
108 | cleancache_invalidate_inode(mapping); |
109 | } |
110 | EXPORT_SYMBOL(invalidate_bdev); |
111 | |
112 | int set_blocksize(struct block_device *bdev, int size) |
113 | { |
114 | /* Size must be a power of two, and between 512 and PAGE_SIZE */ |
115 | if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size)) |
116 | return -EINVAL; |
117 | |
118 | /* Size cannot be smaller than the size supported by the device */ |
119 | if (size < bdev_logical_block_size(bdev)) |
120 | return -EINVAL; |
121 | |
122 | /* Don't change the size if it is same as current */ |
123 | if (bdev->bd_block_size != size) { |
124 | sync_blockdev(bdev); |
125 | bdev->bd_block_size = size; |
126 | bdev->bd_inode->i_blkbits = blksize_bits(size); |
127 | kill_bdev(bdev); |
128 | } |
129 | return 0; |
130 | } |
131 | |
132 | EXPORT_SYMBOL(set_blocksize); |
133 | |
134 | int sb_set_blocksize(struct super_block *sb, int size) |
135 | { |
136 | if (set_blocksize(sb->s_bdev, size)) |
137 | return 0; |
138 | /* If we get here, we know size is power of two |
139 | * and it's value is between 512 and PAGE_SIZE */ |
140 | sb->s_blocksize = size; |
141 | sb->s_blocksize_bits = blksize_bits(size); |
142 | return sb->s_blocksize; |
143 | } |
144 | |
145 | EXPORT_SYMBOL(sb_set_blocksize); |
146 | |
147 | int sb_min_blocksize(struct super_block *sb, int size) |
148 | { |
149 | int minsize = bdev_logical_block_size(sb->s_bdev); |
150 | if (size < minsize) |
151 | size = minsize; |
152 | return sb_set_blocksize(sb, size); |
153 | } |
154 | |
155 | EXPORT_SYMBOL(sb_min_blocksize); |
156 | |
157 | static int |
158 | blkdev_get_block(struct inode *inode, sector_t iblock, |
159 | struct buffer_head *bh, int create) |
160 | { |
161 | bh->b_bdev = I_BDEV(inode); |
162 | bh->b_blocknr = iblock; |
163 | set_buffer_mapped(bh); |
164 | return 0; |
165 | } |
166 | |
167 | static ssize_t |
168 | blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
169 | loff_t offset, unsigned long nr_segs) |
170 | { |
171 | struct file *file = iocb->ki_filp; |
172 | struct inode *inode = file->f_mapping->host; |
173 | |
174 | return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset, |
175 | nr_segs, blkdev_get_block, NULL, NULL, 0); |
176 | } |
177 | |
178 | int __sync_blockdev(struct block_device *bdev, int wait) |
179 | { |
180 | if (!bdev) |
181 | return 0; |
182 | if (!wait) |
183 | return filemap_flush(bdev->bd_inode->i_mapping); |
184 | return filemap_write_and_wait(bdev->bd_inode->i_mapping); |
185 | } |
186 | |
187 | /* |
188 | * Write out and wait upon all the dirty data associated with a block |
189 | * device via its mapping. Does not take the superblock lock. |
190 | */ |
191 | int sync_blockdev(struct block_device *bdev) |
192 | { |
193 | return __sync_blockdev(bdev, 1); |
194 | } |
195 | EXPORT_SYMBOL(sync_blockdev); |
196 | |
197 | /* |
198 | * Write out and wait upon all dirty data associated with this |
199 | * device. Filesystem data as well as the underlying block |
200 | * device. Takes the superblock lock. |
201 | */ |
202 | int fsync_bdev(struct block_device *bdev) |
203 | { |
204 | struct super_block *sb = get_super(bdev); |
205 | if (sb) { |
206 | int res = sync_filesystem(sb); |
207 | drop_super(sb); |
208 | return res; |
209 | } |
210 | return sync_blockdev(bdev); |
211 | } |
212 | EXPORT_SYMBOL(fsync_bdev); |
213 | |
214 | /** |
215 | * freeze_bdev -- lock a filesystem and force it into a consistent state |
216 | * @bdev: blockdevice to lock |
217 | * |
218 | * If a superblock is found on this device, we take the s_umount semaphore |
219 | * on it to make sure nobody unmounts until the snapshot creation is done. |
220 | * The reference counter (bd_fsfreeze_count) guarantees that only the last |
221 | * unfreeze process can unfreeze the frozen filesystem actually when multiple |
222 | * freeze requests arrive simultaneously. It counts up in freeze_bdev() and |
223 | * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze |
224 | * actually. |
225 | */ |
226 | struct super_block *freeze_bdev(struct block_device *bdev) |
227 | { |
228 | struct super_block *sb; |
229 | int error = 0; |
230 | |
231 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
232 | if (++bdev->bd_fsfreeze_count > 1) { |
233 | /* |
234 | * We don't even need to grab a reference - the first call |
235 | * to freeze_bdev grab an active reference and only the last |
236 | * thaw_bdev drops it. |
237 | */ |
238 | sb = get_super(bdev); |
239 | drop_super(sb); |
240 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
241 | return sb; |
242 | } |
243 | |
244 | sb = get_active_super(bdev); |
245 | if (!sb) |
246 | goto out; |
247 | error = freeze_super(sb); |
248 | if (error) { |
249 | deactivate_super(sb); |
250 | bdev->bd_fsfreeze_count--; |
251 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
252 | return ERR_PTR(error); |
253 | } |
254 | deactivate_super(sb); |
255 | out: |
256 | sync_blockdev(bdev); |
257 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
258 | return sb; /* thaw_bdev releases s->s_umount */ |
259 | } |
260 | EXPORT_SYMBOL(freeze_bdev); |
261 | |
262 | /** |
263 | * thaw_bdev -- unlock filesystem |
264 | * @bdev: blockdevice to unlock |
265 | * @sb: associated superblock |
266 | * |
267 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). |
268 | */ |
269 | int thaw_bdev(struct block_device *bdev, struct super_block *sb) |
270 | { |
271 | int error = -EINVAL; |
272 | |
273 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
274 | if (!bdev->bd_fsfreeze_count) |
275 | goto out; |
276 | |
277 | error = 0; |
278 | if (--bdev->bd_fsfreeze_count > 0) |
279 | goto out; |
280 | |
281 | if (!sb) |
282 | goto out; |
283 | |
284 | error = thaw_super(sb); |
285 | if (error) { |
286 | bdev->bd_fsfreeze_count++; |
287 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
288 | return error; |
289 | } |
290 | out: |
291 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
292 | return 0; |
293 | } |
294 | EXPORT_SYMBOL(thaw_bdev); |
295 | |
296 | static int blkdev_writepage(struct page *page, struct writeback_control *wbc) |
297 | { |
298 | return block_write_full_page(page, blkdev_get_block, wbc); |
299 | } |
300 | |
301 | static int blkdev_readpage(struct file * file, struct page * page) |
302 | { |
303 | return block_read_full_page(page, blkdev_get_block); |
304 | } |
305 | |
306 | static int blkdev_write_begin(struct file *file, struct address_space *mapping, |
307 | loff_t pos, unsigned len, unsigned flags, |
308 | struct page **pagep, void **fsdata) |
309 | { |
310 | return block_write_begin(mapping, pos, len, flags, pagep, |
311 | blkdev_get_block); |
312 | } |
313 | |
314 | static int blkdev_write_end(struct file *file, struct address_space *mapping, |
315 | loff_t pos, unsigned len, unsigned copied, |
316 | struct page *page, void *fsdata) |
317 | { |
318 | int ret; |
319 | ret = block_write_end(file, mapping, pos, len, copied, page, fsdata); |
320 | |
321 | unlock_page(page); |
322 | page_cache_release(page); |
323 | |
324 | return ret; |
325 | } |
326 | |
327 | /* |
328 | * private llseek: |
329 | * for a block special file file_inode(file)->i_size is zero |
330 | * so we compute the size by hand (just as in block_read/write above) |
331 | */ |
332 | static loff_t block_llseek(struct file *file, loff_t offset, int whence) |
333 | { |
334 | struct inode *bd_inode = file->f_mapping->host; |
335 | loff_t retval; |
336 | |
337 | mutex_lock(&bd_inode->i_mutex); |
338 | retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode)); |
339 | mutex_unlock(&bd_inode->i_mutex); |
340 | return retval; |
341 | } |
342 | |
343 | int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) |
344 | { |
345 | struct inode *bd_inode = filp->f_mapping->host; |
346 | struct block_device *bdev = I_BDEV(bd_inode); |
347 | int error; |
348 | |
349 | error = filemap_write_and_wait_range(filp->f_mapping, start, end); |
350 | if (error) |
351 | return error; |
352 | |
353 | /* |
354 | * There is no need to serialise calls to blkdev_issue_flush with |
355 | * i_mutex and doing so causes performance issues with concurrent |
356 | * O_SYNC writers to a block device. |
357 | */ |
358 | error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL); |
359 | if (error == -EOPNOTSUPP) |
360 | error = 0; |
361 | |
362 | return error; |
363 | } |
364 | EXPORT_SYMBOL(blkdev_fsync); |
365 | |
366 | /* |
367 | * pseudo-fs |
368 | */ |
369 | |
370 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock); |
371 | static struct kmem_cache * bdev_cachep __read_mostly; |
372 | |
373 | static struct inode *bdev_alloc_inode(struct super_block *sb) |
374 | { |
375 | struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL); |
376 | if (!ei) |
377 | return NULL; |
378 | return &ei->vfs_inode; |
379 | } |
380 | |
381 | static void bdev_i_callback(struct rcu_head *head) |
382 | { |
383 | struct inode *inode = container_of(head, struct inode, i_rcu); |
384 | struct bdev_inode *bdi = BDEV_I(inode); |
385 | |
386 | kmem_cache_free(bdev_cachep, bdi); |
387 | } |
388 | |
389 | static void bdev_destroy_inode(struct inode *inode) |
390 | { |
391 | call_rcu(&inode->i_rcu, bdev_i_callback); |
392 | } |
393 | |
394 | static void init_once(void *foo) |
395 | { |
396 | struct bdev_inode *ei = (struct bdev_inode *) foo; |
397 | struct block_device *bdev = &ei->bdev; |
398 | |
399 | memset(bdev, 0, sizeof(*bdev)); |
400 | mutex_init(&bdev->bd_mutex); |
401 | INIT_LIST_HEAD(&bdev->bd_inodes); |
402 | INIT_LIST_HEAD(&bdev->bd_list); |
403 | #ifdef CONFIG_SYSFS |
404 | INIT_LIST_HEAD(&bdev->bd_holder_disks); |
405 | #endif |
406 | inode_init_once(&ei->vfs_inode); |
407 | /* Initialize mutex for freeze. */ |
408 | mutex_init(&bdev->bd_fsfreeze_mutex); |
409 | } |
410 | |
411 | static inline void __bd_forget(struct inode *inode) |
412 | { |
413 | list_del_init(&inode->i_devices); |
414 | inode->i_bdev = NULL; |
415 | inode->i_mapping = &inode->i_data; |
416 | } |
417 | |
418 | static void bdev_evict_inode(struct inode *inode) |
419 | { |
420 | struct block_device *bdev = &BDEV_I(inode)->bdev; |
421 | struct list_head *p; |
422 | truncate_inode_pages_final(&inode->i_data); |
423 | invalidate_inode_buffers(inode); /* is it needed here? */ |
424 | clear_inode(inode); |
425 | spin_lock(&bdev_lock); |
426 | while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) { |
427 | __bd_forget(list_entry(p, struct inode, i_devices)); |
428 | } |
429 | list_del_init(&bdev->bd_list); |
430 | spin_unlock(&bdev_lock); |
431 | } |
432 | |
433 | static const struct super_operations bdev_sops = { |
434 | .statfs = simple_statfs, |
435 | .alloc_inode = bdev_alloc_inode, |
436 | .destroy_inode = bdev_destroy_inode, |
437 | .drop_inode = generic_delete_inode, |
438 | .evict_inode = bdev_evict_inode, |
439 | }; |
440 | |
441 | static struct dentry *bd_mount(struct file_system_type *fs_type, |
442 | int flags, const char *dev_name, void *data) |
443 | { |
444 | return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC); |
445 | } |
446 | |
447 | static struct file_system_type bd_type = { |
448 | .name = "bdev", |
449 | .mount = bd_mount, |
450 | .kill_sb = kill_anon_super, |
451 | }; |
452 | |
453 | static struct super_block *blockdev_superblock __read_mostly; |
454 | |
455 | void __init bdev_cache_init(void) |
456 | { |
457 | int err; |
458 | static struct vfsmount *bd_mnt; |
459 | |
460 | bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode), |
461 | 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| |
462 | SLAB_MEM_SPREAD|SLAB_PANIC), |
463 | init_once); |
464 | err = register_filesystem(&bd_type); |
465 | if (err) |
466 | panic("Cannot register bdev pseudo-fs"); |
467 | bd_mnt = kern_mount(&bd_type); |
468 | if (IS_ERR(bd_mnt)) |
469 | panic("Cannot create bdev pseudo-fs"); |
470 | blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ |
471 | } |
472 | |
473 | /* |
474 | * Most likely _very_ bad one - but then it's hardly critical for small |
475 | * /dev and can be fixed when somebody will need really large one. |
476 | * Keep in mind that it will be fed through icache hash function too. |
477 | */ |
478 | static inline unsigned long hash(dev_t dev) |
479 | { |
480 | return MAJOR(dev)+MINOR(dev); |
481 | } |
482 | |
483 | static int bdev_test(struct inode *inode, void *data) |
484 | { |
485 | return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data; |
486 | } |
487 | |
488 | static int bdev_set(struct inode *inode, void *data) |
489 | { |
490 | BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data; |
491 | return 0; |
492 | } |
493 | |
494 | static LIST_HEAD(all_bdevs); |
495 | |
496 | struct block_device *bdget(dev_t dev) |
497 | { |
498 | struct block_device *bdev; |
499 | struct inode *inode; |
500 | |
501 | inode = iget5_locked(blockdev_superblock, hash(dev), |
502 | bdev_test, bdev_set, &dev); |
503 | |
504 | if (!inode) |
505 | return NULL; |
506 | |
507 | bdev = &BDEV_I(inode)->bdev; |
508 | |
509 | if (inode->i_state & I_NEW) { |
510 | bdev->bd_contains = NULL; |
511 | bdev->bd_super = NULL; |
512 | bdev->bd_inode = inode; |
513 | bdev->bd_block_size = (1 << inode->i_blkbits); |
514 | bdev->bd_part_count = 0; |
515 | bdev->bd_invalidated = 0; |
516 | inode->i_mode = S_IFBLK; |
517 | inode->i_rdev = dev; |
518 | inode->i_bdev = bdev; |
519 | inode->i_data.a_ops = &def_blk_aops; |
520 | mapping_set_gfp_mask(&inode->i_data, GFP_USER); |
521 | inode->i_data.backing_dev_info = &default_backing_dev_info; |
522 | spin_lock(&bdev_lock); |
523 | list_add(&bdev->bd_list, &all_bdevs); |
524 | spin_unlock(&bdev_lock); |
525 | unlock_new_inode(inode); |
526 | } |
527 | return bdev; |
528 | } |
529 | |
530 | EXPORT_SYMBOL(bdget); |
531 | |
532 | /** |
533 | * bdgrab -- Grab a reference to an already referenced block device |
534 | * @bdev: Block device to grab a reference to. |
535 | */ |
536 | struct block_device *bdgrab(struct block_device *bdev) |
537 | { |
538 | ihold(bdev->bd_inode); |
539 | return bdev; |
540 | } |
541 | EXPORT_SYMBOL(bdgrab); |
542 | |
543 | long nr_blockdev_pages(void) |
544 | { |
545 | struct block_device *bdev; |
546 | long ret = 0; |
547 | spin_lock(&bdev_lock); |
548 | list_for_each_entry(bdev, &all_bdevs, bd_list) { |
549 | ret += bdev->bd_inode->i_mapping->nrpages; |
550 | } |
551 | spin_unlock(&bdev_lock); |
552 | return ret; |
553 | } |
554 | |
555 | void bdput(struct block_device *bdev) |
556 | { |
557 | iput(bdev->bd_inode); |
558 | } |
559 | |
560 | EXPORT_SYMBOL(bdput); |
561 | |
562 | static struct block_device *bd_acquire(struct inode *inode) |
563 | { |
564 | struct block_device *bdev; |
565 | |
566 | spin_lock(&bdev_lock); |
567 | bdev = inode->i_bdev; |
568 | if (bdev) { |
569 | ihold(bdev->bd_inode); |
570 | spin_unlock(&bdev_lock); |
571 | return bdev; |
572 | } |
573 | spin_unlock(&bdev_lock); |
574 | |
575 | bdev = bdget(inode->i_rdev); |
576 | if (bdev) { |
577 | spin_lock(&bdev_lock); |
578 | if (!inode->i_bdev) { |
579 | /* |
580 | * We take an additional reference to bd_inode, |
581 | * and it's released in clear_inode() of inode. |
582 | * So, we can access it via ->i_mapping always |
583 | * without igrab(). |
584 | */ |
585 | ihold(bdev->bd_inode); |
586 | inode->i_bdev = bdev; |
587 | inode->i_mapping = bdev->bd_inode->i_mapping; |
588 | list_add(&inode->i_devices, &bdev->bd_inodes); |
589 | } |
590 | spin_unlock(&bdev_lock); |
591 | } |
592 | return bdev; |
593 | } |
594 | |
595 | int sb_is_blkdev_sb(struct super_block *sb) |
596 | { |
597 | return sb == blockdev_superblock; |
598 | } |
599 | |
600 | /* Call when you free inode */ |
601 | |
602 | void bd_forget(struct inode *inode) |
603 | { |
604 | struct block_device *bdev = NULL; |
605 | |
606 | spin_lock(&bdev_lock); |
607 | if (!sb_is_blkdev_sb(inode->i_sb)) |
608 | bdev = inode->i_bdev; |
609 | __bd_forget(inode); |
610 | spin_unlock(&bdev_lock); |
611 | |
612 | if (bdev) |
613 | iput(bdev->bd_inode); |
614 | } |
615 | |
616 | /** |
617 | * bd_may_claim - test whether a block device can be claimed |
618 | * @bdev: block device of interest |
619 | * @whole: whole block device containing @bdev, may equal @bdev |
620 | * @holder: holder trying to claim @bdev |
621 | * |
622 | * Test whether @bdev can be claimed by @holder. |
623 | * |
624 | * CONTEXT: |
625 | * spin_lock(&bdev_lock). |
626 | * |
627 | * RETURNS: |
628 | * %true if @bdev can be claimed, %false otherwise. |
629 | */ |
630 | static bool bd_may_claim(struct block_device *bdev, struct block_device *whole, |
631 | void *holder) |
632 | { |
633 | if (bdev->bd_holder == holder) |
634 | return true; /* already a holder */ |
635 | else if (bdev->bd_holder != NULL) |
636 | return false; /* held by someone else */ |
637 | else if (bdev->bd_contains == bdev) |
638 | return true; /* is a whole device which isn't held */ |
639 | |
640 | else if (whole->bd_holder == bd_may_claim) |
641 | return true; /* is a partition of a device that is being partitioned */ |
642 | else if (whole->bd_holder != NULL) |
643 | return false; /* is a partition of a held device */ |
644 | else |
645 | return true; /* is a partition of an un-held device */ |
646 | } |
647 | |
648 | /** |
649 | * bd_prepare_to_claim - prepare to claim a block device |
650 | * @bdev: block device of interest |
651 | * @whole: the whole device containing @bdev, may equal @bdev |
652 | * @holder: holder trying to claim @bdev |
653 | * |
654 | * Prepare to claim @bdev. This function fails if @bdev is already |
655 | * claimed by another holder and waits if another claiming is in |
656 | * progress. This function doesn't actually claim. On successful |
657 | * return, the caller has ownership of bd_claiming and bd_holder[s]. |
658 | * |
659 | * CONTEXT: |
660 | * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab |
661 | * it multiple times. |
662 | * |
663 | * RETURNS: |
664 | * 0 if @bdev can be claimed, -EBUSY otherwise. |
665 | */ |
666 | static int bd_prepare_to_claim(struct block_device *bdev, |
667 | struct block_device *whole, void *holder) |
668 | { |
669 | retry: |
670 | /* if someone else claimed, fail */ |
671 | if (!bd_may_claim(bdev, whole, holder)) |
672 | return -EBUSY; |
673 | |
674 | /* if claiming is already in progress, wait for it to finish */ |
675 | if (whole->bd_claiming) { |
676 | wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0); |
677 | DEFINE_WAIT(wait); |
678 | |
679 | prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); |
680 | spin_unlock(&bdev_lock); |
681 | schedule(); |
682 | finish_wait(wq, &wait); |
683 | spin_lock(&bdev_lock); |
684 | goto retry; |
685 | } |
686 | |
687 | /* yay, all mine */ |
688 | return 0; |
689 | } |
690 | |
691 | /** |
692 | * bd_start_claiming - start claiming a block device |
693 | * @bdev: block device of interest |
694 | * @holder: holder trying to claim @bdev |
695 | * |
696 | * @bdev is about to be opened exclusively. Check @bdev can be opened |
697 | * exclusively and mark that an exclusive open is in progress. Each |
698 | * successful call to this function must be matched with a call to |
699 | * either bd_finish_claiming() or bd_abort_claiming() (which do not |
700 | * fail). |
701 | * |
702 | * This function is used to gain exclusive access to the block device |
703 | * without actually causing other exclusive open attempts to fail. It |
704 | * should be used when the open sequence itself requires exclusive |
705 | * access but may subsequently fail. |
706 | * |
707 | * CONTEXT: |
708 | * Might sleep. |
709 | * |
710 | * RETURNS: |
711 | * Pointer to the block device containing @bdev on success, ERR_PTR() |
712 | * value on failure. |
713 | */ |
714 | static struct block_device *bd_start_claiming(struct block_device *bdev, |
715 | void *holder) |
716 | { |
717 | struct gendisk *disk; |
718 | struct block_device *whole; |
719 | int partno, err; |
720 | |
721 | might_sleep(); |
722 | |
723 | /* |
724 | * @bdev might not have been initialized properly yet, look up |
725 | * and grab the outer block device the hard way. |
726 | */ |
727 | disk = get_gendisk(bdev->bd_dev, &partno); |
728 | if (!disk) |
729 | return ERR_PTR(-ENXIO); |
730 | |
731 | /* |
732 | * Normally, @bdev should equal what's returned from bdget_disk() |
733 | * if partno is 0; however, some drivers (floppy) use multiple |
734 | * bdev's for the same physical device and @bdev may be one of the |
735 | * aliases. Keep @bdev if partno is 0. This means claimer |
736 | * tracking is broken for those devices but it has always been that |
737 | * way. |
738 | */ |
739 | if (partno) |
740 | whole = bdget_disk(disk, 0); |
741 | else |
742 | whole = bdgrab(bdev); |
743 | |
744 | module_put(disk->fops->owner); |
745 | put_disk(disk); |
746 | if (!whole) |
747 | return ERR_PTR(-ENOMEM); |
748 | |
749 | /* prepare to claim, if successful, mark claiming in progress */ |
750 | spin_lock(&bdev_lock); |
751 | |
752 | err = bd_prepare_to_claim(bdev, whole, holder); |
753 | if (err == 0) { |
754 | whole->bd_claiming = holder; |
755 | spin_unlock(&bdev_lock); |
756 | return whole; |
757 | } else { |
758 | spin_unlock(&bdev_lock); |
759 | bdput(whole); |
760 | return ERR_PTR(err); |
761 | } |
762 | } |
763 | |
764 | #ifdef CONFIG_SYSFS |
765 | struct bd_holder_disk { |
766 | struct list_head list; |
767 | struct gendisk *disk; |
768 | int refcnt; |
769 | }; |
770 | |
771 | static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev, |
772 | struct gendisk *disk) |
773 | { |
774 | struct bd_holder_disk *holder; |
775 | |
776 | list_for_each_entry(holder, &bdev->bd_holder_disks, list) |
777 | if (holder->disk == disk) |
778 | return holder; |
779 | return NULL; |
780 | } |
781 | |
782 | static int add_symlink(struct kobject *from, struct kobject *to) |
783 | { |
784 | return sysfs_create_link(from, to, kobject_name(to)); |
785 | } |
786 | |
787 | static void del_symlink(struct kobject *from, struct kobject *to) |
788 | { |
789 | sysfs_remove_link(from, kobject_name(to)); |
790 | } |
791 | |
792 | /** |
793 | * bd_link_disk_holder - create symlinks between holding disk and slave bdev |
794 | * @bdev: the claimed slave bdev |
795 | * @disk: the holding disk |
796 | * |
797 | * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. |
798 | * |
799 | * This functions creates the following sysfs symlinks. |
800 | * |
801 | * - from "slaves" directory of the holder @disk to the claimed @bdev |
802 | * - from "holders" directory of the @bdev to the holder @disk |
803 | * |
804 | * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is |
805 | * passed to bd_link_disk_holder(), then: |
806 | * |
807 | * /sys/block/dm-0/slaves/sda --> /sys/block/sda |
808 | * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0 |
809 | * |
810 | * The caller must have claimed @bdev before calling this function and |
811 | * ensure that both @bdev and @disk are valid during the creation and |
812 | * lifetime of these symlinks. |
813 | * |
814 | * CONTEXT: |
815 | * Might sleep. |
816 | * |
817 | * RETURNS: |
818 | * 0 on success, -errno on failure. |
819 | */ |
820 | int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) |
821 | { |
822 | struct bd_holder_disk *holder; |
823 | int ret = 0; |
824 | |
825 | mutex_lock(&bdev->bd_mutex); |
826 | |
827 | WARN_ON_ONCE(!bdev->bd_holder); |
828 | |
829 | /* FIXME: remove the following once add_disk() handles errors */ |
830 | if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir)) |
831 | goto out_unlock; |
832 | |
833 | holder = bd_find_holder_disk(bdev, disk); |
834 | if (holder) { |
835 | holder->refcnt++; |
836 | goto out_unlock; |
837 | } |
838 | |
839 | holder = kzalloc(sizeof(*holder), GFP_KERNEL); |
840 | if (!holder) { |
841 | ret = -ENOMEM; |
842 | goto out_unlock; |
843 | } |
844 | |
845 | INIT_LIST_HEAD(&holder->list); |
846 | holder->disk = disk; |
847 | holder->refcnt = 1; |
848 | |
849 | ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
850 | if (ret) |
851 | goto out_free; |
852 | |
853 | ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); |
854 | if (ret) |
855 | goto out_del; |
856 | /* |
857 | * bdev could be deleted beneath us which would implicitly destroy |
858 | * the holder directory. Hold on to it. |
859 | */ |
860 | kobject_get(bdev->bd_part->holder_dir); |
861 | |
862 | list_add(&holder->list, &bdev->bd_holder_disks); |
863 | goto out_unlock; |
864 | |
865 | out_del: |
866 | del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
867 | out_free: |
868 | kfree(holder); |
869 | out_unlock: |
870 | mutex_unlock(&bdev->bd_mutex); |
871 | return ret; |
872 | } |
873 | EXPORT_SYMBOL_GPL(bd_link_disk_holder); |
874 | |
875 | /** |
876 | * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder() |
877 | * @bdev: the calimed slave bdev |
878 | * @disk: the holding disk |
879 | * |
880 | * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. |
881 | * |
882 | * CONTEXT: |
883 | * Might sleep. |
884 | */ |
885 | void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) |
886 | { |
887 | struct bd_holder_disk *holder; |
888 | |
889 | mutex_lock(&bdev->bd_mutex); |
890 | |
891 | holder = bd_find_holder_disk(bdev, disk); |
892 | |
893 | if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) { |
894 | del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
895 | del_symlink(bdev->bd_part->holder_dir, |
896 | &disk_to_dev(disk)->kobj); |
897 | kobject_put(bdev->bd_part->holder_dir); |
898 | list_del_init(&holder->list); |
899 | kfree(holder); |
900 | } |
901 | |
902 | mutex_unlock(&bdev->bd_mutex); |
903 | } |
904 | EXPORT_SYMBOL_GPL(bd_unlink_disk_holder); |
905 | #endif |
906 | |
907 | /** |
908 | * flush_disk - invalidates all buffer-cache entries on a disk |
909 | * |
910 | * @bdev: struct block device to be flushed |
911 | * @kill_dirty: flag to guide handling of dirty inodes |
912 | * |
913 | * Invalidates all buffer-cache entries on a disk. It should be called |
914 | * when a disk has been changed -- either by a media change or online |
915 | * resize. |
916 | */ |
917 | static void flush_disk(struct block_device *bdev, bool kill_dirty) |
918 | { |
919 | if (__invalidate_device(bdev, kill_dirty)) { |
920 | char name[BDEVNAME_SIZE] = ""; |
921 | |
922 | if (bdev->bd_disk) |
923 | disk_name(bdev->bd_disk, 0, name); |
924 | printk(KERN_WARNING "VFS: busy inodes on changed media or " |
925 | "resized disk %s\n", name); |
926 | } |
927 | |
928 | if (!bdev->bd_disk) |
929 | return; |
930 | if (disk_part_scan_enabled(bdev->bd_disk)) |
931 | bdev->bd_invalidated = 1; |
932 | } |
933 | |
934 | /** |
935 | * check_disk_size_change - checks for disk size change and adjusts bdev size. |
936 | * @disk: struct gendisk to check |
937 | * @bdev: struct bdev to adjust. |
938 | * |
939 | * This routine checks to see if the bdev size does not match the disk size |
940 | * and adjusts it if it differs. |
941 | */ |
942 | void check_disk_size_change(struct gendisk *disk, struct block_device *bdev) |
943 | { |
944 | loff_t disk_size, bdev_size; |
945 | |
946 | disk_size = (loff_t)get_capacity(disk) << 9; |
947 | bdev_size = i_size_read(bdev->bd_inode); |
948 | if (disk_size != bdev_size) { |
949 | char name[BDEVNAME_SIZE]; |
950 | |
951 | disk_name(disk, 0, name); |
952 | printk(KERN_INFO |
953 | "%s: detected capacity change from %lld to %lld\n", |
954 | name, bdev_size, disk_size); |
955 | i_size_write(bdev->bd_inode, disk_size); |
956 | flush_disk(bdev, false); |
957 | } |
958 | } |
959 | EXPORT_SYMBOL(check_disk_size_change); |
960 | |
961 | /** |
962 | * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back |
963 | * @disk: struct gendisk to be revalidated |
964 | * |
965 | * This routine is a wrapper for lower-level driver's revalidate_disk |
966 | * call-backs. It is used to do common pre and post operations needed |
967 | * for all revalidate_disk operations. |
968 | */ |
969 | int revalidate_disk(struct gendisk *disk) |
970 | { |
971 | struct block_device *bdev; |
972 | int ret = 0; |
973 | |
974 | if (disk->fops->revalidate_disk) |
975 | ret = disk->fops->revalidate_disk(disk); |
976 | |
977 | bdev = bdget_disk(disk, 0); |
978 | if (!bdev) |
979 | return ret; |
980 | |
981 | mutex_lock(&bdev->bd_mutex); |
982 | check_disk_size_change(disk, bdev); |
983 | bdev->bd_invalidated = 0; |
984 | mutex_unlock(&bdev->bd_mutex); |
985 | bdput(bdev); |
986 | return ret; |
987 | } |
988 | EXPORT_SYMBOL(revalidate_disk); |
989 | |
990 | /* |
991 | * This routine checks whether a removable media has been changed, |
992 | * and invalidates all buffer-cache-entries in that case. This |
993 | * is a relatively slow routine, so we have to try to minimize using |
994 | * it. Thus it is called only upon a 'mount' or 'open'. This |
995 | * is the best way of combining speed and utility, I think. |
996 | * People changing diskettes in the middle of an operation deserve |
997 | * to lose :-) |
998 | */ |
999 | int check_disk_change(struct block_device *bdev) |
1000 | { |
1001 | struct gendisk *disk = bdev->bd_disk; |
1002 | const struct block_device_operations *bdops = disk->fops; |
1003 | unsigned int events; |
1004 | |
1005 | events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE | |
1006 | DISK_EVENT_EJECT_REQUEST); |
1007 | if (!(events & DISK_EVENT_MEDIA_CHANGE)) |
1008 | return 0; |
1009 | |
1010 | flush_disk(bdev, true); |
1011 | if (bdops->revalidate_disk) |
1012 | bdops->revalidate_disk(bdev->bd_disk); |
1013 | return 1; |
1014 | } |
1015 | |
1016 | EXPORT_SYMBOL(check_disk_change); |
1017 | |
1018 | void bd_set_size(struct block_device *bdev, loff_t size) |
1019 | { |
1020 | unsigned bsize = bdev_logical_block_size(bdev); |
1021 | |
1022 | mutex_lock(&bdev->bd_inode->i_mutex); |
1023 | i_size_write(bdev->bd_inode, size); |
1024 | mutex_unlock(&bdev->bd_inode->i_mutex); |
1025 | while (bsize < PAGE_CACHE_SIZE) { |
1026 | if (size & bsize) |
1027 | break; |
1028 | bsize <<= 1; |
1029 | } |
1030 | bdev->bd_block_size = bsize; |
1031 | bdev->bd_inode->i_blkbits = blksize_bits(bsize); |
1032 | } |
1033 | EXPORT_SYMBOL(bd_set_size); |
1034 | |
1035 | static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part); |
1036 | |
1037 | /* |
1038 | * bd_mutex locking: |
1039 | * |
1040 | * mutex_lock(part->bd_mutex) |
1041 | * mutex_lock_nested(whole->bd_mutex, 1) |
1042 | */ |
1043 | |
1044 | static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) |
1045 | { |
1046 | struct gendisk *disk; |
1047 | struct module *owner; |
1048 | int ret; |
1049 | int partno; |
1050 | int perm = 0; |
1051 | |
1052 | if (mode & FMODE_READ) |
1053 | perm |= MAY_READ; |
1054 | if (mode & FMODE_WRITE) |
1055 | perm |= MAY_WRITE; |
1056 | /* |
1057 | * hooks: /n/, see "layering violations". |
1058 | */ |
1059 | if (!for_part) { |
1060 | ret = devcgroup_inode_permission(bdev->bd_inode, perm); |
1061 | if (ret != 0) { |
1062 | bdput(bdev); |
1063 | return ret; |
1064 | } |
1065 | } |
1066 | |
1067 | restart: |
1068 | |
1069 | ret = -ENXIO; |
1070 | disk = get_gendisk(bdev->bd_dev, &partno); |
1071 | if (!disk) |
1072 | goto out; |
1073 | owner = disk->fops->owner; |
1074 | |
1075 | disk_block_events(disk); |
1076 | mutex_lock_nested(&bdev->bd_mutex, for_part); |
1077 | if (!bdev->bd_openers) { |
1078 | bdev->bd_disk = disk; |
1079 | bdev->bd_queue = disk->queue; |
1080 | bdev->bd_contains = bdev; |
1081 | if (!partno) { |
1082 | struct backing_dev_info *bdi; |
1083 | |
1084 | ret = -ENXIO; |
1085 | bdev->bd_part = disk_get_part(disk, partno); |
1086 | if (!bdev->bd_part) |
1087 | goto out_clear; |
1088 | |
1089 | ret = 0; |
1090 | if (disk->fops->open) { |
1091 | ret = disk->fops->open(bdev, mode); |
1092 | if (ret == -ERESTARTSYS) { |
1093 | /* Lost a race with 'disk' being |
1094 | * deleted, try again. |
1095 | * See md.c |
1096 | */ |
1097 | disk_put_part(bdev->bd_part); |
1098 | bdev->bd_part = NULL; |
1099 | bdev->bd_disk = NULL; |
1100 | bdev->bd_queue = NULL; |
1101 | mutex_unlock(&bdev->bd_mutex); |
1102 | disk_unblock_events(disk); |
1103 | put_disk(disk); |
1104 | module_put(owner); |
1105 | goto restart; |
1106 | } |
1107 | } |
1108 | |
1109 | if (!ret) { |
1110 | bd_set_size(bdev,(loff_t)get_capacity(disk)<<9); |
1111 | bdi = blk_get_backing_dev_info(bdev); |
1112 | if (bdi == NULL) |
1113 | bdi = &default_backing_dev_info; |
1114 | bdev_inode_switch_bdi(bdev->bd_inode, bdi); |
1115 | } |
1116 | |
1117 | /* |
1118 | * If the device is invalidated, rescan partition |
1119 | * if open succeeded or failed with -ENOMEDIUM. |
1120 | * The latter is necessary to prevent ghost |
1121 | * partitions on a removed medium. |
1122 | */ |
1123 | if (bdev->bd_invalidated) { |
1124 | if (!ret) |
1125 | rescan_partitions(disk, bdev); |
1126 | else if (ret == -ENOMEDIUM) |
1127 | invalidate_partitions(disk, bdev); |
1128 | } |
1129 | if (ret) |
1130 | goto out_clear; |
1131 | } else { |
1132 | struct block_device *whole; |
1133 | whole = bdget_disk(disk, 0); |
1134 | ret = -ENOMEM; |
1135 | if (!whole) |
1136 | goto out_clear; |
1137 | BUG_ON(for_part); |
1138 | ret = __blkdev_get(whole, mode, 1); |
1139 | if (ret) |
1140 | goto out_clear; |
1141 | bdev->bd_contains = whole; |
1142 | bdev_inode_switch_bdi(bdev->bd_inode, |
1143 | whole->bd_inode->i_data.backing_dev_info); |
1144 | bdev->bd_part = disk_get_part(disk, partno); |
1145 | if (!(disk->flags & GENHD_FL_UP) || |
1146 | !bdev->bd_part || !bdev->bd_part->nr_sects) { |
1147 | ret = -ENXIO; |
1148 | goto out_clear; |
1149 | } |
1150 | bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9); |
1151 | } |
1152 | } else { |
1153 | if (bdev->bd_contains == bdev) { |
1154 | ret = 0; |
1155 | if (bdev->bd_disk->fops->open) |
1156 | ret = bdev->bd_disk->fops->open(bdev, mode); |
1157 | /* the same as first opener case, read comment there */ |
1158 | if (bdev->bd_invalidated) { |
1159 | if (!ret) |
1160 | rescan_partitions(bdev->bd_disk, bdev); |
1161 | else if (ret == -ENOMEDIUM) |
1162 | invalidate_partitions(bdev->bd_disk, bdev); |
1163 | } |
1164 | if (ret) |
1165 | goto out_unlock_bdev; |
1166 | } |
1167 | /* only one opener holds refs to the module and disk */ |
1168 | put_disk(disk); |
1169 | module_put(owner); |
1170 | } |
1171 | bdev->bd_openers++; |
1172 | if (for_part) |
1173 | bdev->bd_part_count++; |
1174 | mutex_unlock(&bdev->bd_mutex); |
1175 | disk_unblock_events(disk); |
1176 | return 0; |
1177 | |
1178 | out_clear: |
1179 | disk_put_part(bdev->bd_part); |
1180 | bdev->bd_disk = NULL; |
1181 | bdev->bd_part = NULL; |
1182 | bdev->bd_queue = NULL; |
1183 | bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info); |
1184 | if (bdev != bdev->bd_contains) |
1185 | __blkdev_put(bdev->bd_contains, mode, 1); |
1186 | bdev->bd_contains = NULL; |
1187 | out_unlock_bdev: |
1188 | mutex_unlock(&bdev->bd_mutex); |
1189 | disk_unblock_events(disk); |
1190 | put_disk(disk); |
1191 | module_put(owner); |
1192 | out: |
1193 | bdput(bdev); |
1194 | |
1195 | return ret; |
1196 | } |
1197 | |
1198 | /** |
1199 | * blkdev_get - open a block device |
1200 | * @bdev: block_device to open |
1201 | * @mode: FMODE_* mask |
1202 | * @holder: exclusive holder identifier |
1203 | * |
1204 | * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is |
1205 | * open with exclusive access. Specifying %FMODE_EXCL with %NULL |
1206 | * @holder is invalid. Exclusive opens may nest for the same @holder. |
1207 | * |
1208 | * On success, the reference count of @bdev is unchanged. On failure, |
1209 | * @bdev is put. |
1210 | * |
1211 | * CONTEXT: |
1212 | * Might sleep. |
1213 | * |
1214 | * RETURNS: |
1215 | * 0 on success, -errno on failure. |
1216 | */ |
1217 | int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) |
1218 | { |
1219 | struct block_device *whole = NULL; |
1220 | int res; |
1221 | |
1222 | WARN_ON_ONCE((mode & FMODE_EXCL) && !holder); |
1223 | |
1224 | if ((mode & FMODE_EXCL) && holder) { |
1225 | whole = bd_start_claiming(bdev, holder); |
1226 | if (IS_ERR(whole)) { |
1227 | bdput(bdev); |
1228 | return PTR_ERR(whole); |
1229 | } |
1230 | } |
1231 | |
1232 | res = __blkdev_get(bdev, mode, 0); |
1233 | |
1234 | if (whole) { |
1235 | struct gendisk *disk = whole->bd_disk; |
1236 | |
1237 | /* finish claiming */ |
1238 | mutex_lock(&bdev->bd_mutex); |
1239 | spin_lock(&bdev_lock); |
1240 | |
1241 | if (!res) { |
1242 | BUG_ON(!bd_may_claim(bdev, whole, holder)); |
1243 | /* |
1244 | * Note that for a whole device bd_holders |
1245 | * will be incremented twice, and bd_holder |
1246 | * will be set to bd_may_claim before being |
1247 | * set to holder |
1248 | */ |
1249 | whole->bd_holders++; |
1250 | whole->bd_holder = bd_may_claim; |
1251 | bdev->bd_holders++; |
1252 | bdev->bd_holder = holder; |
1253 | } |
1254 | |
1255 | /* tell others that we're done */ |
1256 | BUG_ON(whole->bd_claiming != holder); |
1257 | whole->bd_claiming = NULL; |
1258 | wake_up_bit(&whole->bd_claiming, 0); |
1259 | |
1260 | spin_unlock(&bdev_lock); |
1261 | |
1262 | /* |
1263 | * Block event polling for write claims if requested. Any |
1264 | * write holder makes the write_holder state stick until |
1265 | * all are released. This is good enough and tracking |
1266 | * individual writeable reference is too fragile given the |
1267 | * way @mode is used in blkdev_get/put(). |
1268 | */ |
1269 | if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder && |
1270 | (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { |
1271 | bdev->bd_write_holder = true; |
1272 | disk_block_events(disk); |
1273 | } |
1274 | |
1275 | mutex_unlock(&bdev->bd_mutex); |
1276 | bdput(whole); |
1277 | } |
1278 | |
1279 | return res; |
1280 | } |
1281 | EXPORT_SYMBOL(blkdev_get); |
1282 | |
1283 | /** |
1284 | * blkdev_get_by_path - open a block device by name |
1285 | * @path: path to the block device to open |
1286 | * @mode: FMODE_* mask |
1287 | * @holder: exclusive holder identifier |
1288 | * |
1289 | * Open the blockdevice described by the device file at @path. @mode |
1290 | * and @holder are identical to blkdev_get(). |
1291 | * |
1292 | * On success, the returned block_device has reference count of one. |
1293 | * |
1294 | * CONTEXT: |
1295 | * Might sleep. |
1296 | * |
1297 | * RETURNS: |
1298 | * Pointer to block_device on success, ERR_PTR(-errno) on failure. |
1299 | */ |
1300 | struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, |
1301 | void *holder) |
1302 | { |
1303 | struct block_device *bdev; |
1304 | int err; |
1305 | |
1306 | bdev = lookup_bdev(path); |
1307 | if (IS_ERR(bdev)) |
1308 | return bdev; |
1309 | |
1310 | err = blkdev_get(bdev, mode, holder); |
1311 | if (err) |
1312 | return ERR_PTR(err); |
1313 | |
1314 | if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) { |
1315 | blkdev_put(bdev, mode); |
1316 | return ERR_PTR(-EACCES); |
1317 | } |
1318 | |
1319 | return bdev; |
1320 | } |
1321 | EXPORT_SYMBOL(blkdev_get_by_path); |
1322 | |
1323 | /** |
1324 | * blkdev_get_by_dev - open a block device by device number |
1325 | * @dev: device number of block device to open |
1326 | * @mode: FMODE_* mask |
1327 | * @holder: exclusive holder identifier |
1328 | * |
1329 | * Open the blockdevice described by device number @dev. @mode and |
1330 | * @holder are identical to blkdev_get(). |
1331 | * |
1332 | * Use it ONLY if you really do not have anything better - i.e. when |
1333 | * you are behind a truly sucky interface and all you are given is a |
1334 | * device number. _Never_ to be used for internal purposes. If you |
1335 | * ever need it - reconsider your API. |
1336 | * |
1337 | * On success, the returned block_device has reference count of one. |
1338 | * |
1339 | * CONTEXT: |
1340 | * Might sleep. |
1341 | * |
1342 | * RETURNS: |
1343 | * Pointer to block_device on success, ERR_PTR(-errno) on failure. |
1344 | */ |
1345 | struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) |
1346 | { |
1347 | struct block_device *bdev; |
1348 | int err; |
1349 | |
1350 | bdev = bdget(dev); |
1351 | if (!bdev) |
1352 | return ERR_PTR(-ENOMEM); |
1353 | |
1354 | err = blkdev_get(bdev, mode, holder); |
1355 | if (err) |
1356 | return ERR_PTR(err); |
1357 | |
1358 | return bdev; |
1359 | } |
1360 | EXPORT_SYMBOL(blkdev_get_by_dev); |
1361 | |
1362 | static int blkdev_open(struct inode * inode, struct file * filp) |
1363 | { |
1364 | struct block_device *bdev; |
1365 | |
1366 | /* |
1367 | * Preserve backwards compatibility and allow large file access |
1368 | * even if userspace doesn't ask for it explicitly. Some mkfs |
1369 | * binary needs it. We might want to drop this workaround |
1370 | * during an unstable branch. |
1371 | */ |
1372 | filp->f_flags |= O_LARGEFILE; |
1373 | |
1374 | if (filp->f_flags & O_NDELAY) |
1375 | filp->f_mode |= FMODE_NDELAY; |
1376 | if (filp->f_flags & O_EXCL) |
1377 | filp->f_mode |= FMODE_EXCL; |
1378 | if ((filp->f_flags & O_ACCMODE) == 3) |
1379 | filp->f_mode |= FMODE_WRITE_IOCTL; |
1380 | |
1381 | bdev = bd_acquire(inode); |
1382 | if (bdev == NULL) |
1383 | return -ENOMEM; |
1384 | |
1385 | filp->f_mapping = bdev->bd_inode->i_mapping; |
1386 | |
1387 | return blkdev_get(bdev, filp->f_mode, filp); |
1388 | } |
1389 | |
1390 | static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) |
1391 | { |
1392 | struct gendisk *disk = bdev->bd_disk; |
1393 | struct block_device *victim = NULL; |
1394 | |
1395 | mutex_lock_nested(&bdev->bd_mutex, for_part); |
1396 | if (for_part) |
1397 | bdev->bd_part_count--; |
1398 | |
1399 | if (!--bdev->bd_openers) { |
1400 | WARN_ON_ONCE(bdev->bd_holders); |
1401 | sync_blockdev(bdev); |
1402 | kill_bdev(bdev); |
1403 | /* ->release can cause the old bdi to disappear, |
1404 | * so must switch it out first |
1405 | */ |
1406 | bdev_inode_switch_bdi(bdev->bd_inode, |
1407 | &default_backing_dev_info); |
1408 | } |
1409 | if (bdev->bd_contains == bdev) { |
1410 | if (disk->fops->release) |
1411 | disk->fops->release(disk, mode); |
1412 | } |
1413 | if (!bdev->bd_openers) { |
1414 | struct module *owner = disk->fops->owner; |
1415 | |
1416 | disk_put_part(bdev->bd_part); |
1417 | bdev->bd_part = NULL; |
1418 | bdev->bd_disk = NULL; |
1419 | if (bdev != bdev->bd_contains) |
1420 | victim = bdev->bd_contains; |
1421 | bdev->bd_contains = NULL; |
1422 | |
1423 | put_disk(disk); |
1424 | module_put(owner); |
1425 | } |
1426 | mutex_unlock(&bdev->bd_mutex); |
1427 | bdput(bdev); |
1428 | if (victim) |
1429 | __blkdev_put(victim, mode, 1); |
1430 | } |
1431 | |
1432 | void blkdev_put(struct block_device *bdev, fmode_t mode) |
1433 | { |
1434 | mutex_lock(&bdev->bd_mutex); |
1435 | |
1436 | if (mode & FMODE_EXCL) { |
1437 | bool bdev_free; |
1438 | |
1439 | /* |
1440 | * Release a claim on the device. The holder fields |
1441 | * are protected with bdev_lock. bd_mutex is to |
1442 | * synchronize disk_holder unlinking. |
1443 | */ |
1444 | spin_lock(&bdev_lock); |
1445 | |
1446 | WARN_ON_ONCE(--bdev->bd_holders < 0); |
1447 | WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0); |
1448 | |
1449 | /* bd_contains might point to self, check in a separate step */ |
1450 | if ((bdev_free = !bdev->bd_holders)) |
1451 | bdev->bd_holder = NULL; |
1452 | if (!bdev->bd_contains->bd_holders) |
1453 | bdev->bd_contains->bd_holder = NULL; |
1454 | |
1455 | spin_unlock(&bdev_lock); |
1456 | |
1457 | /* |
1458 | * If this was the last claim, remove holder link and |
1459 | * unblock evpoll if it was a write holder. |
1460 | */ |
1461 | if (bdev_free && bdev->bd_write_holder) { |
1462 | disk_unblock_events(bdev->bd_disk); |
1463 | bdev->bd_write_holder = false; |
1464 | } |
1465 | } |
1466 | |
1467 | /* |
1468 | * Trigger event checking and tell drivers to flush MEDIA_CHANGE |
1469 | * event. This is to ensure detection of media removal commanded |
1470 | * from userland - e.g. eject(1). |
1471 | */ |
1472 | disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE); |
1473 | |
1474 | mutex_unlock(&bdev->bd_mutex); |
1475 | |
1476 | __blkdev_put(bdev, mode, 0); |
1477 | } |
1478 | EXPORT_SYMBOL(blkdev_put); |
1479 | |
1480 | static int blkdev_close(struct inode * inode, struct file * filp) |
1481 | { |
1482 | struct block_device *bdev = I_BDEV(filp->f_mapping->host); |
1483 | blkdev_put(bdev, filp->f_mode); |
1484 | return 0; |
1485 | } |
1486 | |
1487 | static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg) |
1488 | { |
1489 | struct block_device *bdev = I_BDEV(file->f_mapping->host); |
1490 | fmode_t mode = file->f_mode; |
1491 | |
1492 | /* |
1493 | * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have |
1494 | * to updated it before every ioctl. |
1495 | */ |
1496 | if (file->f_flags & O_NDELAY) |
1497 | mode |= FMODE_NDELAY; |
1498 | else |
1499 | mode &= ~FMODE_NDELAY; |
1500 | |
1501 | return blkdev_ioctl(bdev, mode, cmd, arg); |
1502 | } |
1503 | |
1504 | /* |
1505 | * Write data to the block device. Only intended for the block device itself |
1506 | * and the raw driver which basically is a fake block device. |
1507 | * |
1508 | * Does not take i_mutex for the write and thus is not for general purpose |
1509 | * use. |
1510 | */ |
1511 | ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov, |
1512 | unsigned long nr_segs, loff_t pos) |
1513 | { |
1514 | struct file *file = iocb->ki_filp; |
1515 | struct blk_plug plug; |
1516 | ssize_t ret; |
1517 | |
1518 | BUG_ON(iocb->ki_pos != pos); |
1519 | |
1520 | blk_start_plug(&plug); |
1521 | ret = __generic_file_aio_write(iocb, iov, nr_segs); |
1522 | if (ret > 0) { |
1523 | ssize_t err; |
1524 | |
1525 | err = generic_write_sync(file, pos, ret); |
1526 | if (err < 0) |
1527 | ret = err; |
1528 | } |
1529 | blk_finish_plug(&plug); |
1530 | return ret; |
1531 | } |
1532 | EXPORT_SYMBOL_GPL(blkdev_aio_write); |
1533 | |
1534 | static ssize_t blkdev_aio_read(struct kiocb *iocb, const struct iovec *iov, |
1535 | unsigned long nr_segs, loff_t pos) |
1536 | { |
1537 | struct file *file = iocb->ki_filp; |
1538 | struct inode *bd_inode = file->f_mapping->host; |
1539 | loff_t size = i_size_read(bd_inode); |
1540 | |
1541 | if (pos >= size) |
1542 | return 0; |
1543 | |
1544 | size -= pos; |
1545 | if (size < iocb->ki_nbytes) |
1546 | nr_segs = iov_shorten((struct iovec *)iov, nr_segs, size); |
1547 | return generic_file_aio_read(iocb, iov, nr_segs, pos); |
1548 | } |
1549 | |
1550 | /* |
1551 | * Try to release a page associated with block device when the system |
1552 | * is under memory pressure. |
1553 | */ |
1554 | static int blkdev_releasepage(struct page *page, gfp_t wait) |
1555 | { |
1556 | struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super; |
1557 | |
1558 | if (super && super->s_op->bdev_try_to_free_page) |
1559 | return super->s_op->bdev_try_to_free_page(super, page, wait); |
1560 | |
1561 | return try_to_free_buffers(page); |
1562 | } |
1563 | |
1564 | static const struct address_space_operations def_blk_aops = { |
1565 | .readpage = blkdev_readpage, |
1566 | .writepage = blkdev_writepage, |
1567 | .write_begin = blkdev_write_begin, |
1568 | .write_end = blkdev_write_end, |
1569 | .writepages = generic_writepages, |
1570 | .releasepage = blkdev_releasepage, |
1571 | .direct_IO = blkdev_direct_IO, |
1572 | .is_dirty_writeback = buffer_check_dirty_writeback, |
1573 | }; |
1574 | |
1575 | const struct file_operations def_blk_fops = { |
1576 | .open = blkdev_open, |
1577 | .release = blkdev_close, |
1578 | .llseek = block_llseek, |
1579 | .read = do_sync_read, |
1580 | .write = do_sync_write, |
1581 | .aio_read = blkdev_aio_read, |
1582 | .aio_write = blkdev_aio_write, |
1583 | .mmap = generic_file_mmap, |
1584 | .fsync = blkdev_fsync, |
1585 | .unlocked_ioctl = block_ioctl, |
1586 | #ifdef CONFIG_COMPAT |
1587 | .compat_ioctl = compat_blkdev_ioctl, |
1588 | #endif |
1589 | .splice_read = generic_file_splice_read, |
1590 | .splice_write = generic_file_splice_write, |
1591 | }; |
1592 | |
1593 | int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg) |
1594 | { |
1595 | int res; |
1596 | mm_segment_t old_fs = get_fs(); |
1597 | set_fs(KERNEL_DS); |
1598 | res = blkdev_ioctl(bdev, 0, cmd, arg); |
1599 | set_fs(old_fs); |
1600 | return res; |
1601 | } |
1602 | |
1603 | EXPORT_SYMBOL(ioctl_by_bdev); |
1604 | |
1605 | /** |
1606 | * lookup_bdev - lookup a struct block_device by name |
1607 | * @pathname: special file representing the block device |
1608 | * |
1609 | * Get a reference to the blockdevice at @pathname in the current |
1610 | * namespace if possible and return it. Return ERR_PTR(error) |
1611 | * otherwise. |
1612 | */ |
1613 | struct block_device *lookup_bdev(const char *pathname) |
1614 | { |
1615 | struct block_device *bdev; |
1616 | struct inode *inode; |
1617 | struct path path; |
1618 | int error; |
1619 | |
1620 | if (!pathname || !*pathname) |
1621 | return ERR_PTR(-EINVAL); |
1622 | |
1623 | error = kern_path(pathname, LOOKUP_FOLLOW, &path); |
1624 | if (error) |
1625 | return ERR_PTR(error); |
1626 | |
1627 | inode = path.dentry->d_inode; |
1628 | error = -ENOTBLK; |
1629 | if (!S_ISBLK(inode->i_mode)) |
1630 | goto fail; |
1631 | error = -EACCES; |
1632 | if (path.mnt->mnt_flags & MNT_NODEV) |
1633 | goto fail; |
1634 | error = -ENOMEM; |
1635 | bdev = bd_acquire(inode); |
1636 | if (!bdev) |
1637 | goto fail; |
1638 | out: |
1639 | path_put(&path); |
1640 | return bdev; |
1641 | fail: |
1642 | bdev = ERR_PTR(error); |
1643 | goto out; |
1644 | } |
1645 | EXPORT_SYMBOL(lookup_bdev); |
1646 | |
1647 | int __invalidate_device(struct block_device *bdev, bool kill_dirty) |
1648 | { |
1649 | struct super_block *sb = get_super(bdev); |
1650 | int res = 0; |
1651 | |
1652 | if (sb) { |
1653 | /* |
1654 | * no need to lock the super, get_super holds the |
1655 | * read mutex so the filesystem cannot go away |
1656 | * under us (->put_super runs with the write lock |
1657 | * hold). |
1658 | */ |
1659 | shrink_dcache_sb(sb); |
1660 | res = invalidate_inodes(sb, kill_dirty); |
1661 | drop_super(sb); |
1662 | } |
1663 | invalidate_bdev(bdev); |
1664 | return res; |
1665 | } |
1666 | EXPORT_SYMBOL(__invalidate_device); |
1667 | |
1668 | void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg) |
1669 | { |
1670 | struct inode *inode, *old_inode = NULL; |
1671 | |
1672 | spin_lock(&inode_sb_list_lock); |
1673 | list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) { |
1674 | struct address_space *mapping = inode->i_mapping; |
1675 | |
1676 | spin_lock(&inode->i_lock); |
1677 | if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) || |
1678 | mapping->nrpages == 0) { |
1679 | spin_unlock(&inode->i_lock); |
1680 | continue; |
1681 | } |
1682 | __iget(inode); |
1683 | spin_unlock(&inode->i_lock); |
1684 | spin_unlock(&inode_sb_list_lock); |
1685 | /* |
1686 | * We hold a reference to 'inode' so it couldn't have been |
1687 | * removed from s_inodes list while we dropped the |
1688 | * inode_sb_list_lock. We cannot iput the inode now as we can |
1689 | * be holding the last reference and we cannot iput it under |
1690 | * inode_sb_list_lock. So we keep the reference and iput it |
1691 | * later. |
1692 | */ |
1693 | iput(old_inode); |
1694 | old_inode = inode; |
1695 | |
1696 | func(I_BDEV(inode), arg); |
1697 | |
1698 | spin_lock(&inode_sb_list_lock); |
1699 | } |
1700 | spin_unlock(&inode_sb_list_lock); |
1701 | iput(old_inode); |
1702 | } |
1703 |
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