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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/buffer_head.h> |
20 | #include <linux/swap.h> |
21 | #include <linux/pagevec.h> |
22 | #include <linux/writeback.h> |
23 | #include <linux/mpage.h> |
24 | #include <linux/mount.h> |
25 | #include <linux/uio.h> |
26 | #include <linux/namei.h> |
27 | #include <linux/log2.h> |
28 | #include <linux/cleancache.h> |
29 | #include <asm/uaccess.h> |
30 | #include "internal.h" |
31 | |
32 | struct bdev_inode { |
33 | struct block_device bdev; |
34 | struct inode vfs_inode; |
35 | }; |
36 | |
37 | static const struct address_space_operations def_blk_aops; |
38 | |
39 | static inline struct bdev_inode *BDEV_I(struct inode *inode) |
40 | { |
41 | return container_of(inode, struct bdev_inode, vfs_inode); |
42 | } |
43 | |
44 | inline struct block_device *I_BDEV(struct inode *inode) |
45 | { |
46 | return &BDEV_I(inode)->bdev; |
47 | } |
48 | EXPORT_SYMBOL(I_BDEV); |
49 | |
50 | /* |
51 | * Move the inode from its current bdi to a new bdi. If the inode is dirty we |
52 | * need to move it onto the dirty list of @dst so that the inode is always on |
53 | * the right list. |
54 | */ |
55 | static void bdev_inode_switch_bdi(struct inode *inode, |
56 | struct backing_dev_info *dst) |
57 | { |
58 | struct backing_dev_info *old = inode->i_data.backing_dev_info; |
59 | |
60 | if (unlikely(dst == old)) /* deadlock avoidance */ |
61 | return; |
62 | bdi_lock_two(&old->wb, &dst->wb); |
63 | spin_lock(&inode->i_lock); |
64 | inode->i_data.backing_dev_info = dst; |
65 | if (inode->i_state & I_DIRTY) |
66 | list_move(&inode->i_wb_list, &dst->wb.b_dirty); |
67 | spin_unlock(&inode->i_lock); |
68 | spin_unlock(&old->wb.list_lock); |
69 | spin_unlock(&dst->wb.list_lock); |
70 | } |
71 | |
72 | static sector_t max_block(struct block_device *bdev) |
73 | { |
74 | sector_t retval = ~((sector_t)0); |
75 | loff_t sz = i_size_read(bdev->bd_inode); |
76 | |
77 | if (sz) { |
78 | unsigned int size = block_size(bdev); |
79 | unsigned int sizebits = blksize_bits(size); |
80 | retval = (sz >> sizebits); |
81 | } |
82 | return retval; |
83 | } |
84 | |
85 | /* Kill _all_ buffers and pagecache , dirty or not.. */ |
86 | void kill_bdev(struct block_device *bdev) |
87 | { |
88 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
89 | |
90 | if (mapping->nrpages == 0) |
91 | return; |
92 | |
93 | invalidate_bh_lrus(); |
94 | truncate_inode_pages(mapping, 0); |
95 | } |
96 | EXPORT_SYMBOL(kill_bdev); |
97 | |
98 | /* Invalidate clean unused buffers and pagecache. */ |
99 | void invalidate_bdev(struct block_device *bdev) |
100 | { |
101 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
102 | |
103 | if (mapping->nrpages == 0) |
104 | return; |
105 | |
106 | invalidate_bh_lrus(); |
107 | lru_add_drain_all(); /* make sure all lru add caches are flushed */ |
108 | invalidate_mapping_pages(mapping, 0, -1); |
109 | /* 99% of the time, we don't need to flush the cleancache on the bdev. |
110 | * But, for the strange corners, lets be cautious |
111 | */ |
112 | cleancache_flush_inode(mapping); |
113 | } |
114 | EXPORT_SYMBOL(invalidate_bdev); |
115 | |
116 | int set_blocksize(struct block_device *bdev, int size) |
117 | { |
118 | /* Size must be a power of two, and between 512 and PAGE_SIZE */ |
119 | if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size)) |
120 | return -EINVAL; |
121 | |
122 | /* Size cannot be smaller than the size supported by the device */ |
123 | if (size < bdev_logical_block_size(bdev)) |
124 | return -EINVAL; |
125 | |
126 | /* Don't change the size if it is same as current */ |
127 | if (bdev->bd_block_size != size) { |
128 | sync_blockdev(bdev); |
129 | bdev->bd_block_size = size; |
130 | bdev->bd_inode->i_blkbits = blksize_bits(size); |
131 | kill_bdev(bdev); |
132 | } |
133 | return 0; |
134 | } |
135 | |
136 | EXPORT_SYMBOL(set_blocksize); |
137 | |
138 | int sb_set_blocksize(struct super_block *sb, int size) |
139 | { |
140 | if (set_blocksize(sb->s_bdev, size)) |
141 | return 0; |
142 | /* If we get here, we know size is power of two |
143 | * and it's value is between 512 and PAGE_SIZE */ |
144 | sb->s_blocksize = size; |
145 | sb->s_blocksize_bits = blksize_bits(size); |
146 | return sb->s_blocksize; |
147 | } |
148 | |
149 | EXPORT_SYMBOL(sb_set_blocksize); |
150 | |
151 | int sb_min_blocksize(struct super_block *sb, int size) |
152 | { |
153 | int minsize = bdev_logical_block_size(sb->s_bdev); |
154 | if (size < minsize) |
155 | size = minsize; |
156 | return sb_set_blocksize(sb, size); |
157 | } |
158 | |
159 | EXPORT_SYMBOL(sb_min_blocksize); |
160 | |
161 | static int |
162 | blkdev_get_block(struct inode *inode, sector_t iblock, |
163 | struct buffer_head *bh, int create) |
164 | { |
165 | if (iblock >= max_block(I_BDEV(inode))) { |
166 | if (create) |
167 | return -EIO; |
168 | |
169 | /* |
170 | * for reads, we're just trying to fill a partial page. |
171 | * return a hole, they will have to call get_block again |
172 | * before they can fill it, and they will get -EIO at that |
173 | * time |
174 | */ |
175 | return 0; |
176 | } |
177 | bh->b_bdev = I_BDEV(inode); |
178 | bh->b_blocknr = iblock; |
179 | set_buffer_mapped(bh); |
180 | return 0; |
181 | } |
182 | |
183 | static int |
184 | blkdev_get_blocks(struct inode *inode, sector_t iblock, |
185 | struct buffer_head *bh, int create) |
186 | { |
187 | sector_t end_block = max_block(I_BDEV(inode)); |
188 | unsigned long max_blocks = bh->b_size >> inode->i_blkbits; |
189 | |
190 | if ((iblock + max_blocks) > end_block) { |
191 | max_blocks = end_block - iblock; |
192 | if ((long)max_blocks <= 0) { |
193 | if (create) |
194 | return -EIO; /* write fully beyond EOF */ |
195 | /* |
196 | * It is a read which is fully beyond EOF. We return |
197 | * a !buffer_mapped buffer |
198 | */ |
199 | max_blocks = 0; |
200 | } |
201 | } |
202 | |
203 | bh->b_bdev = I_BDEV(inode); |
204 | bh->b_blocknr = iblock; |
205 | bh->b_size = max_blocks << inode->i_blkbits; |
206 | if (max_blocks) |
207 | set_buffer_mapped(bh); |
208 | return 0; |
209 | } |
210 | |
211 | static ssize_t |
212 | blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
213 | loff_t offset, unsigned long nr_segs) |
214 | { |
215 | struct file *file = iocb->ki_filp; |
216 | struct inode *inode = file->f_mapping->host; |
217 | |
218 | return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset, |
219 | nr_segs, blkdev_get_blocks, NULL, NULL, 0); |
220 | } |
221 | |
222 | int __sync_blockdev(struct block_device *bdev, int wait) |
223 | { |
224 | if (!bdev) |
225 | return 0; |
226 | if (!wait) |
227 | return filemap_flush(bdev->bd_inode->i_mapping); |
228 | return filemap_write_and_wait(bdev->bd_inode->i_mapping); |
229 | } |
230 | |
231 | /* |
232 | * Write out and wait upon all the dirty data associated with a block |
233 | * device via its mapping. Does not take the superblock lock. |
234 | */ |
235 | int sync_blockdev(struct block_device *bdev) |
236 | { |
237 | return __sync_blockdev(bdev, 1); |
238 | } |
239 | EXPORT_SYMBOL(sync_blockdev); |
240 | |
241 | /* |
242 | * Write out and wait upon all dirty data associated with this |
243 | * device. Filesystem data as well as the underlying block |
244 | * device. Takes the superblock lock. |
245 | */ |
246 | int fsync_bdev(struct block_device *bdev) |
247 | { |
248 | struct super_block *sb = get_super(bdev); |
249 | if (sb) { |
250 | int res = sync_filesystem(sb); |
251 | drop_super(sb); |
252 | return res; |
253 | } |
254 | return sync_blockdev(bdev); |
255 | } |
256 | EXPORT_SYMBOL(fsync_bdev); |
257 | |
258 | /** |
259 | * freeze_bdev -- lock a filesystem and force it into a consistent state |
260 | * @bdev: blockdevice to lock |
261 | * |
262 | * If a superblock is found on this device, we take the s_umount semaphore |
263 | * on it to make sure nobody unmounts until the snapshot creation is done. |
264 | * The reference counter (bd_fsfreeze_count) guarantees that only the last |
265 | * unfreeze process can unfreeze the frozen filesystem actually when multiple |
266 | * freeze requests arrive simultaneously. It counts up in freeze_bdev() and |
267 | * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze |
268 | * actually. |
269 | */ |
270 | struct super_block *freeze_bdev(struct block_device *bdev) |
271 | { |
272 | struct super_block *sb; |
273 | int error = 0; |
274 | |
275 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
276 | if (++bdev->bd_fsfreeze_count > 1) { |
277 | /* |
278 | * We don't even need to grab a reference - the first call |
279 | * to freeze_bdev grab an active reference and only the last |
280 | * thaw_bdev drops it. |
281 | */ |
282 | sb = get_super(bdev); |
283 | drop_super(sb); |
284 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
285 | return sb; |
286 | } |
287 | |
288 | sb = get_active_super(bdev); |
289 | if (!sb) |
290 | goto out; |
291 | error = freeze_super(sb); |
292 | if (error) { |
293 | deactivate_super(sb); |
294 | bdev->bd_fsfreeze_count--; |
295 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
296 | return ERR_PTR(error); |
297 | } |
298 | deactivate_super(sb); |
299 | out: |
300 | sync_blockdev(bdev); |
301 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
302 | return sb; /* thaw_bdev releases s->s_umount */ |
303 | } |
304 | EXPORT_SYMBOL(freeze_bdev); |
305 | |
306 | /** |
307 | * thaw_bdev -- unlock filesystem |
308 | * @bdev: blockdevice to unlock |
309 | * @sb: associated superblock |
310 | * |
311 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). |
312 | */ |
313 | int thaw_bdev(struct block_device *bdev, struct super_block *sb) |
314 | { |
315 | int error = -EINVAL; |
316 | |
317 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
318 | if (!bdev->bd_fsfreeze_count) |
319 | goto out; |
320 | |
321 | error = 0; |
322 | if (--bdev->bd_fsfreeze_count > 0) |
323 | goto out; |
324 | |
325 | if (!sb) |
326 | goto out; |
327 | |
328 | error = thaw_super(sb); |
329 | if (error) { |
330 | bdev->bd_fsfreeze_count++; |
331 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
332 | return error; |
333 | } |
334 | out: |
335 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
336 | return 0; |
337 | } |
338 | EXPORT_SYMBOL(thaw_bdev); |
339 | |
340 | static int blkdev_writepage(struct page *page, struct writeback_control *wbc) |
341 | { |
342 | return block_write_full_page(page, blkdev_get_block, wbc); |
343 | } |
344 | |
345 | static int blkdev_readpage(struct file * file, struct page * page) |
346 | { |
347 | return block_read_full_page(page, blkdev_get_block); |
348 | } |
349 | |
350 | static int blkdev_write_begin(struct file *file, struct address_space *mapping, |
351 | loff_t pos, unsigned len, unsigned flags, |
352 | struct page **pagep, void **fsdata) |
353 | { |
354 | return block_write_begin(mapping, pos, len, flags, pagep, |
355 | blkdev_get_block); |
356 | } |
357 | |
358 | static int blkdev_write_end(struct file *file, struct address_space *mapping, |
359 | loff_t pos, unsigned len, unsigned copied, |
360 | struct page *page, void *fsdata) |
361 | { |
362 | int ret; |
363 | ret = block_write_end(file, mapping, pos, len, copied, page, fsdata); |
364 | |
365 | unlock_page(page); |
366 | page_cache_release(page); |
367 | |
368 | return ret; |
369 | } |
370 | |
371 | /* |
372 | * private llseek: |
373 | * for a block special file file->f_path.dentry->d_inode->i_size is zero |
374 | * so we compute the size by hand (just as in block_read/write above) |
375 | */ |
376 | static loff_t block_llseek(struct file *file, loff_t offset, int origin) |
377 | { |
378 | struct inode *bd_inode = file->f_mapping->host; |
379 | loff_t size; |
380 | loff_t retval; |
381 | |
382 | mutex_lock(&bd_inode->i_mutex); |
383 | size = i_size_read(bd_inode); |
384 | |
385 | retval = -EINVAL; |
386 | switch (origin) { |
387 | case SEEK_END: |
388 | offset += size; |
389 | break; |
390 | case SEEK_CUR: |
391 | offset += file->f_pos; |
392 | case SEEK_SET: |
393 | break; |
394 | default: |
395 | goto out; |
396 | } |
397 | if (offset >= 0 && offset <= size) { |
398 | if (offset != file->f_pos) { |
399 | file->f_pos = offset; |
400 | } |
401 | retval = offset; |
402 | } |
403 | out: |
404 | mutex_unlock(&bd_inode->i_mutex); |
405 | return retval; |
406 | } |
407 | |
408 | int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) |
409 | { |
410 | struct inode *bd_inode = filp->f_mapping->host; |
411 | struct block_device *bdev = I_BDEV(bd_inode); |
412 | int error; |
413 | |
414 | error = filemap_write_and_wait_range(filp->f_mapping, start, end); |
415 | if (error) |
416 | return error; |
417 | |
418 | /* |
419 | * There is no need to serialise calls to blkdev_issue_flush with |
420 | * i_mutex and doing so causes performance issues with concurrent |
421 | * O_SYNC writers to a block device. |
422 | */ |
423 | error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL); |
424 | if (error == -EOPNOTSUPP) |
425 | error = 0; |
426 | |
427 | return error; |
428 | } |
429 | EXPORT_SYMBOL(blkdev_fsync); |
430 | |
431 | /* |
432 | * pseudo-fs |
433 | */ |
434 | |
435 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock); |
436 | static struct kmem_cache * bdev_cachep __read_mostly; |
437 | |
438 | static struct inode *bdev_alloc_inode(struct super_block *sb) |
439 | { |
440 | struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL); |
441 | if (!ei) |
442 | return NULL; |
443 | return &ei->vfs_inode; |
444 | } |
445 | |
446 | static void bdev_i_callback(struct rcu_head *head) |
447 | { |
448 | struct inode *inode = container_of(head, struct inode, i_rcu); |
449 | struct bdev_inode *bdi = BDEV_I(inode); |
450 | |
451 | kmem_cache_free(bdev_cachep, bdi); |
452 | } |
453 | |
454 | static void bdev_destroy_inode(struct inode *inode) |
455 | { |
456 | call_rcu(&inode->i_rcu, bdev_i_callback); |
457 | } |
458 | |
459 | static void init_once(void *foo) |
460 | { |
461 | struct bdev_inode *ei = (struct bdev_inode *) foo; |
462 | struct block_device *bdev = &ei->bdev; |
463 | |
464 | memset(bdev, 0, sizeof(*bdev)); |
465 | mutex_init(&bdev->bd_mutex); |
466 | INIT_LIST_HEAD(&bdev->bd_inodes); |
467 | INIT_LIST_HEAD(&bdev->bd_list); |
468 | #ifdef CONFIG_SYSFS |
469 | INIT_LIST_HEAD(&bdev->bd_holder_disks); |
470 | #endif |
471 | inode_init_once(&ei->vfs_inode); |
472 | /* Initialize mutex for freeze. */ |
473 | mutex_init(&bdev->bd_fsfreeze_mutex); |
474 | } |
475 | |
476 | static inline void __bd_forget(struct inode *inode) |
477 | { |
478 | list_del_init(&inode->i_devices); |
479 | inode->i_bdev = NULL; |
480 | inode->i_mapping = &inode->i_data; |
481 | } |
482 | |
483 | static void bdev_evict_inode(struct inode *inode) |
484 | { |
485 | struct block_device *bdev = &BDEV_I(inode)->bdev; |
486 | struct list_head *p; |
487 | truncate_inode_pages(&inode->i_data, 0); |
488 | invalidate_inode_buffers(inode); /* is it needed here? */ |
489 | end_writeback(inode); |
490 | spin_lock(&bdev_lock); |
491 | while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) { |
492 | __bd_forget(list_entry(p, struct inode, i_devices)); |
493 | } |
494 | list_del_init(&bdev->bd_list); |
495 | spin_unlock(&bdev_lock); |
496 | } |
497 | |
498 | static const struct super_operations bdev_sops = { |
499 | .statfs = simple_statfs, |
500 | .alloc_inode = bdev_alloc_inode, |
501 | .destroy_inode = bdev_destroy_inode, |
502 | .drop_inode = generic_delete_inode, |
503 | .evict_inode = bdev_evict_inode, |
504 | }; |
505 | |
506 | static struct dentry *bd_mount(struct file_system_type *fs_type, |
507 | int flags, const char *dev_name, void *data) |
508 | { |
509 | return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, 0x62646576); |
510 | } |
511 | |
512 | static struct file_system_type bd_type = { |
513 | .name = "bdev", |
514 | .mount = bd_mount, |
515 | .kill_sb = kill_anon_super, |
516 | }; |
517 | |
518 | static struct super_block *blockdev_superblock __read_mostly; |
519 | |
520 | void __init bdev_cache_init(void) |
521 | { |
522 | int err; |
523 | static struct vfsmount *bd_mnt; |
524 | |
525 | bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode), |
526 | 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| |
527 | SLAB_MEM_SPREAD|SLAB_PANIC), |
528 | init_once); |
529 | err = register_filesystem(&bd_type); |
530 | if (err) |
531 | panic("Cannot register bdev pseudo-fs"); |
532 | bd_mnt = kern_mount(&bd_type); |
533 | if (IS_ERR(bd_mnt)) |
534 | panic("Cannot create bdev pseudo-fs"); |
535 | blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ |
536 | } |
537 | |
538 | /* |
539 | * Most likely _very_ bad one - but then it's hardly critical for small |
540 | * /dev and can be fixed when somebody will need really large one. |
541 | * Keep in mind that it will be fed through icache hash function too. |
542 | */ |
543 | static inline unsigned long hash(dev_t dev) |
544 | { |
545 | return MAJOR(dev)+MINOR(dev); |
546 | } |
547 | |
548 | static int bdev_test(struct inode *inode, void *data) |
549 | { |
550 | return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data; |
551 | } |
552 | |
553 | static int bdev_set(struct inode *inode, void *data) |
554 | { |
555 | BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data; |
556 | return 0; |
557 | } |
558 | |
559 | static LIST_HEAD(all_bdevs); |
560 | |
561 | struct block_device *bdget(dev_t dev) |
562 | { |
563 | struct block_device *bdev; |
564 | struct inode *inode; |
565 | |
566 | inode = iget5_locked(blockdev_superblock, hash(dev), |
567 | bdev_test, bdev_set, &dev); |
568 | |
569 | if (!inode) |
570 | return NULL; |
571 | |
572 | bdev = &BDEV_I(inode)->bdev; |
573 | |
574 | if (inode->i_state & I_NEW) { |
575 | bdev->bd_contains = NULL; |
576 | bdev->bd_super = NULL; |
577 | bdev->bd_inode = inode; |
578 | bdev->bd_block_size = (1 << inode->i_blkbits); |
579 | bdev->bd_part_count = 0; |
580 | bdev->bd_invalidated = 0; |
581 | inode->i_mode = S_IFBLK; |
582 | inode->i_rdev = dev; |
583 | inode->i_bdev = bdev; |
584 | inode->i_data.a_ops = &def_blk_aops; |
585 | mapping_set_gfp_mask(&inode->i_data, GFP_USER); |
586 | inode->i_data.backing_dev_info = &default_backing_dev_info; |
587 | spin_lock(&bdev_lock); |
588 | list_add(&bdev->bd_list, &all_bdevs); |
589 | spin_unlock(&bdev_lock); |
590 | unlock_new_inode(inode); |
591 | } |
592 | return bdev; |
593 | } |
594 | |
595 | EXPORT_SYMBOL(bdget); |
596 | |
597 | /** |
598 | * bdgrab -- Grab a reference to an already referenced block device |
599 | * @bdev: Block device to grab a reference to. |
600 | */ |
601 | struct block_device *bdgrab(struct block_device *bdev) |
602 | { |
603 | ihold(bdev->bd_inode); |
604 | return bdev; |
605 | } |
606 | |
607 | long nr_blockdev_pages(void) |
608 | { |
609 | struct block_device *bdev; |
610 | long ret = 0; |
611 | spin_lock(&bdev_lock); |
612 | list_for_each_entry(bdev, &all_bdevs, bd_list) { |
613 | ret += bdev->bd_inode->i_mapping->nrpages; |
614 | } |
615 | spin_unlock(&bdev_lock); |
616 | return ret; |
617 | } |
618 | |
619 | void bdput(struct block_device *bdev) |
620 | { |
621 | iput(bdev->bd_inode); |
622 | } |
623 | |
624 | EXPORT_SYMBOL(bdput); |
625 | |
626 | static struct block_device *bd_acquire(struct inode *inode) |
627 | { |
628 | struct block_device *bdev; |
629 | |
630 | spin_lock(&bdev_lock); |
631 | bdev = inode->i_bdev; |
632 | if (bdev) { |
633 | ihold(bdev->bd_inode); |
634 | spin_unlock(&bdev_lock); |
635 | return bdev; |
636 | } |
637 | spin_unlock(&bdev_lock); |
638 | |
639 | bdev = bdget(inode->i_rdev); |
640 | if (bdev) { |
641 | spin_lock(&bdev_lock); |
642 | if (!inode->i_bdev) { |
643 | /* |
644 | * We take an additional reference to bd_inode, |
645 | * and it's released in clear_inode() of inode. |
646 | * So, we can access it via ->i_mapping always |
647 | * without igrab(). |
648 | */ |
649 | ihold(bdev->bd_inode); |
650 | inode->i_bdev = bdev; |
651 | inode->i_mapping = bdev->bd_inode->i_mapping; |
652 | list_add(&inode->i_devices, &bdev->bd_inodes); |
653 | } |
654 | spin_unlock(&bdev_lock); |
655 | } |
656 | return bdev; |
657 | } |
658 | |
659 | static inline int sb_is_blkdev_sb(struct super_block *sb) |
660 | { |
661 | return sb == blockdev_superblock; |
662 | } |
663 | |
664 | /* Call when you free inode */ |
665 | |
666 | void bd_forget(struct inode *inode) |
667 | { |
668 | struct block_device *bdev = NULL; |
669 | |
670 | spin_lock(&bdev_lock); |
671 | if (inode->i_bdev) { |
672 | if (!sb_is_blkdev_sb(inode->i_sb)) |
673 | bdev = inode->i_bdev; |
674 | __bd_forget(inode); |
675 | } |
676 | spin_unlock(&bdev_lock); |
677 | |
678 | if (bdev) |
679 | iput(bdev->bd_inode); |
680 | } |
681 | |
682 | /** |
683 | * bd_may_claim - test whether a block device can be claimed |
684 | * @bdev: block device of interest |
685 | * @whole: whole block device containing @bdev, may equal @bdev |
686 | * @holder: holder trying to claim @bdev |
687 | * |
688 | * Test whether @bdev can be claimed by @holder. |
689 | * |
690 | * CONTEXT: |
691 | * spin_lock(&bdev_lock). |
692 | * |
693 | * RETURNS: |
694 | * %true if @bdev can be claimed, %false otherwise. |
695 | */ |
696 | static bool bd_may_claim(struct block_device *bdev, struct block_device *whole, |
697 | void *holder) |
698 | { |
699 | if (bdev->bd_holder == holder) |
700 | return true; /* already a holder */ |
701 | else if (bdev->bd_holder != NULL) |
702 | return false; /* held by someone else */ |
703 | else if (bdev->bd_contains == bdev) |
704 | return true; /* is a whole device which isn't held */ |
705 | |
706 | else if (whole->bd_holder == bd_may_claim) |
707 | return true; /* is a partition of a device that is being partitioned */ |
708 | else if (whole->bd_holder != NULL) |
709 | return false; /* is a partition of a held device */ |
710 | else |
711 | return true; /* is a partition of an un-held device */ |
712 | } |
713 | |
714 | /** |
715 | * bd_prepare_to_claim - prepare to claim a block device |
716 | * @bdev: block device of interest |
717 | * @whole: the whole device containing @bdev, may equal @bdev |
718 | * @holder: holder trying to claim @bdev |
719 | * |
720 | * Prepare to claim @bdev. This function fails if @bdev is already |
721 | * claimed by another holder and waits if another claiming is in |
722 | * progress. This function doesn't actually claim. On successful |
723 | * return, the caller has ownership of bd_claiming and bd_holder[s]. |
724 | * |
725 | * CONTEXT: |
726 | * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab |
727 | * it multiple times. |
728 | * |
729 | * RETURNS: |
730 | * 0 if @bdev can be claimed, -EBUSY otherwise. |
731 | */ |
732 | static int bd_prepare_to_claim(struct block_device *bdev, |
733 | struct block_device *whole, void *holder) |
734 | { |
735 | retry: |
736 | /* if someone else claimed, fail */ |
737 | if (!bd_may_claim(bdev, whole, holder)) |
738 | return -EBUSY; |
739 | |
740 | /* if claiming is already in progress, wait for it to finish */ |
741 | if (whole->bd_claiming) { |
742 | wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0); |
743 | DEFINE_WAIT(wait); |
744 | |
745 | prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); |
746 | spin_unlock(&bdev_lock); |
747 | schedule(); |
748 | finish_wait(wq, &wait); |
749 | spin_lock(&bdev_lock); |
750 | goto retry; |
751 | } |
752 | |
753 | /* yay, all mine */ |
754 | return 0; |
755 | } |
756 | |
757 | /** |
758 | * bd_start_claiming - start claiming a block device |
759 | * @bdev: block device of interest |
760 | * @holder: holder trying to claim @bdev |
761 | * |
762 | * @bdev is about to be opened exclusively. Check @bdev can be opened |
763 | * exclusively and mark that an exclusive open is in progress. Each |
764 | * successful call to this function must be matched with a call to |
765 | * either bd_finish_claiming() or bd_abort_claiming() (which do not |
766 | * fail). |
767 | * |
768 | * This function is used to gain exclusive access to the block device |
769 | * without actually causing other exclusive open attempts to fail. It |
770 | * should be used when the open sequence itself requires exclusive |
771 | * access but may subsequently fail. |
772 | * |
773 | * CONTEXT: |
774 | * Might sleep. |
775 | * |
776 | * RETURNS: |
777 | * Pointer to the block device containing @bdev on success, ERR_PTR() |
778 | * value on failure. |
779 | */ |
780 | static struct block_device *bd_start_claiming(struct block_device *bdev, |
781 | void *holder) |
782 | { |
783 | struct gendisk *disk; |
784 | struct block_device *whole; |
785 | int partno, err; |
786 | |
787 | might_sleep(); |
788 | |
789 | /* |
790 | * @bdev might not have been initialized properly yet, look up |
791 | * and grab the outer block device the hard way. |
792 | */ |
793 | disk = get_gendisk(bdev->bd_dev, &partno); |
794 | if (!disk) |
795 | return ERR_PTR(-ENXIO); |
796 | |
797 | /* |
798 | * Normally, @bdev should equal what's returned from bdget_disk() |
799 | * if partno is 0; however, some drivers (floppy) use multiple |
800 | * bdev's for the same physical device and @bdev may be one of the |
801 | * aliases. Keep @bdev if partno is 0. This means claimer |
802 | * tracking is broken for those devices but it has always been that |
803 | * way. |
804 | */ |
805 | if (partno) |
806 | whole = bdget_disk(disk, 0); |
807 | else |
808 | whole = bdgrab(bdev); |
809 | |
810 | module_put(disk->fops->owner); |
811 | put_disk(disk); |
812 | if (!whole) |
813 | return ERR_PTR(-ENOMEM); |
814 | |
815 | /* prepare to claim, if successful, mark claiming in progress */ |
816 | spin_lock(&bdev_lock); |
817 | |
818 | err = bd_prepare_to_claim(bdev, whole, holder); |
819 | if (err == 0) { |
820 | whole->bd_claiming = holder; |
821 | spin_unlock(&bdev_lock); |
822 | return whole; |
823 | } else { |
824 | spin_unlock(&bdev_lock); |
825 | bdput(whole); |
826 | return ERR_PTR(err); |
827 | } |
828 | } |
829 | |
830 | #ifdef CONFIG_SYSFS |
831 | struct bd_holder_disk { |
832 | struct list_head list; |
833 | struct gendisk *disk; |
834 | int refcnt; |
835 | }; |
836 | |
837 | static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev, |
838 | struct gendisk *disk) |
839 | { |
840 | struct bd_holder_disk *holder; |
841 | |
842 | list_for_each_entry(holder, &bdev->bd_holder_disks, list) |
843 | if (holder->disk == disk) |
844 | return holder; |
845 | return NULL; |
846 | } |
847 | |
848 | static int add_symlink(struct kobject *from, struct kobject *to) |
849 | { |
850 | return sysfs_create_link(from, to, kobject_name(to)); |
851 | } |
852 | |
853 | static void del_symlink(struct kobject *from, struct kobject *to) |
854 | { |
855 | sysfs_remove_link(from, kobject_name(to)); |
856 | } |
857 | |
858 | /** |
859 | * bd_link_disk_holder - create symlinks between holding disk and slave bdev |
860 | * @bdev: the claimed slave bdev |
861 | * @disk: the holding disk |
862 | * |
863 | * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. |
864 | * |
865 | * This functions creates the following sysfs symlinks. |
866 | * |
867 | * - from "slaves" directory of the holder @disk to the claimed @bdev |
868 | * - from "holders" directory of the @bdev to the holder @disk |
869 | * |
870 | * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is |
871 | * passed to bd_link_disk_holder(), then: |
872 | * |
873 | * /sys/block/dm-0/slaves/sda --> /sys/block/sda |
874 | * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0 |
875 | * |
876 | * The caller must have claimed @bdev before calling this function and |
877 | * ensure that both @bdev and @disk are valid during the creation and |
878 | * lifetime of these symlinks. |
879 | * |
880 | * CONTEXT: |
881 | * Might sleep. |
882 | * |
883 | * RETURNS: |
884 | * 0 on success, -errno on failure. |
885 | */ |
886 | int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) |
887 | { |
888 | struct bd_holder_disk *holder; |
889 | int ret = 0; |
890 | |
891 | mutex_lock(&bdev->bd_mutex); |
892 | |
893 | WARN_ON_ONCE(!bdev->bd_holder); |
894 | |
895 | /* FIXME: remove the following once add_disk() handles errors */ |
896 | if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir)) |
897 | goto out_unlock; |
898 | |
899 | holder = bd_find_holder_disk(bdev, disk); |
900 | if (holder) { |
901 | holder->refcnt++; |
902 | goto out_unlock; |
903 | } |
904 | |
905 | holder = kzalloc(sizeof(*holder), GFP_KERNEL); |
906 | if (!holder) { |
907 | ret = -ENOMEM; |
908 | goto out_unlock; |
909 | } |
910 | |
911 | INIT_LIST_HEAD(&holder->list); |
912 | holder->disk = disk; |
913 | holder->refcnt = 1; |
914 | |
915 | ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
916 | if (ret) |
917 | goto out_free; |
918 | |
919 | ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); |
920 | if (ret) |
921 | goto out_del; |
922 | /* |
923 | * bdev could be deleted beneath us which would implicitly destroy |
924 | * the holder directory. Hold on to it. |
925 | */ |
926 | kobject_get(bdev->bd_part->holder_dir); |
927 | |
928 | list_add(&holder->list, &bdev->bd_holder_disks); |
929 | goto out_unlock; |
930 | |
931 | out_del: |
932 | del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
933 | out_free: |
934 | kfree(holder); |
935 | out_unlock: |
936 | mutex_unlock(&bdev->bd_mutex); |
937 | return ret; |
938 | } |
939 | EXPORT_SYMBOL_GPL(bd_link_disk_holder); |
940 | |
941 | /** |
942 | * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder() |
943 | * @bdev: the calimed slave bdev |
944 | * @disk: the holding disk |
945 | * |
946 | * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. |
947 | * |
948 | * CONTEXT: |
949 | * Might sleep. |
950 | */ |
951 | void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) |
952 | { |
953 | struct bd_holder_disk *holder; |
954 | |
955 | mutex_lock(&bdev->bd_mutex); |
956 | |
957 | holder = bd_find_holder_disk(bdev, disk); |
958 | |
959 | if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) { |
960 | del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
961 | del_symlink(bdev->bd_part->holder_dir, |
962 | &disk_to_dev(disk)->kobj); |
963 | kobject_put(bdev->bd_part->holder_dir); |
964 | list_del_init(&holder->list); |
965 | kfree(holder); |
966 | } |
967 | |
968 | mutex_unlock(&bdev->bd_mutex); |
969 | } |
970 | EXPORT_SYMBOL_GPL(bd_unlink_disk_holder); |
971 | #endif |
972 | |
973 | /** |
974 | * flush_disk - invalidates all buffer-cache entries on a disk |
975 | * |
976 | * @bdev: struct block device to be flushed |
977 | * @kill_dirty: flag to guide handling of dirty inodes |
978 | * |
979 | * Invalidates all buffer-cache entries on a disk. It should be called |
980 | * when a disk has been changed -- either by a media change or online |
981 | * resize. |
982 | */ |
983 | static void flush_disk(struct block_device *bdev, bool kill_dirty) |
984 | { |
985 | if (__invalidate_device(bdev, kill_dirty)) { |
986 | char name[BDEVNAME_SIZE] = ""; |
987 | |
988 | if (bdev->bd_disk) |
989 | disk_name(bdev->bd_disk, 0, name); |
990 | printk(KERN_WARNING "VFS: busy inodes on changed media or " |
991 | "resized disk %s\n", name); |
992 | } |
993 | |
994 | if (!bdev->bd_disk) |
995 | return; |
996 | if (disk_part_scan_enabled(bdev->bd_disk)) |
997 | bdev->bd_invalidated = 1; |
998 | } |
999 | |
1000 | /** |
1001 | * check_disk_size_change - checks for disk size change and adjusts bdev size. |
1002 | * @disk: struct gendisk to check |
1003 | * @bdev: struct bdev to adjust. |
1004 | * |
1005 | * This routine checks to see if the bdev size does not match the disk size |
1006 | * and adjusts it if it differs. |
1007 | */ |
1008 | void check_disk_size_change(struct gendisk *disk, struct block_device *bdev) |
1009 | { |
1010 | loff_t disk_size, bdev_size; |
1011 | |
1012 | disk_size = (loff_t)get_capacity(disk) << 9; |
1013 | bdev_size = i_size_read(bdev->bd_inode); |
1014 | if (disk_size != bdev_size) { |
1015 | char name[BDEVNAME_SIZE]; |
1016 | |
1017 | disk_name(disk, 0, name); |
1018 | printk(KERN_INFO |
1019 | "%s: detected capacity change from %lld to %lld\n", |
1020 | name, bdev_size, disk_size); |
1021 | i_size_write(bdev->bd_inode, disk_size); |
1022 | flush_disk(bdev, false); |
1023 | } |
1024 | } |
1025 | EXPORT_SYMBOL(check_disk_size_change); |
1026 | |
1027 | /** |
1028 | * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back |
1029 | * @disk: struct gendisk to be revalidated |
1030 | * |
1031 | * This routine is a wrapper for lower-level driver's revalidate_disk |
1032 | * call-backs. It is used to do common pre and post operations needed |
1033 | * for all revalidate_disk operations. |
1034 | */ |
1035 | int revalidate_disk(struct gendisk *disk) |
1036 | { |
1037 | struct block_device *bdev; |
1038 | int ret = 0; |
1039 | |
1040 | if (disk->fops->revalidate_disk) |
1041 | ret = disk->fops->revalidate_disk(disk); |
1042 | |
1043 | bdev = bdget_disk(disk, 0); |
1044 | if (!bdev) |
1045 | return ret; |
1046 | |
1047 | mutex_lock(&bdev->bd_mutex); |
1048 | check_disk_size_change(disk, bdev); |
1049 | mutex_unlock(&bdev->bd_mutex); |
1050 | bdput(bdev); |
1051 | return ret; |
1052 | } |
1053 | EXPORT_SYMBOL(revalidate_disk); |
1054 | |
1055 | /* |
1056 | * This routine checks whether a removable media has been changed, |
1057 | * and invalidates all buffer-cache-entries in that case. This |
1058 | * is a relatively slow routine, so we have to try to minimize using |
1059 | * it. Thus it is called only upon a 'mount' or 'open'. This |
1060 | * is the best way of combining speed and utility, I think. |
1061 | * People changing diskettes in the middle of an operation deserve |
1062 | * to lose :-) |
1063 | */ |
1064 | int check_disk_change(struct block_device *bdev) |
1065 | { |
1066 | struct gendisk *disk = bdev->bd_disk; |
1067 | const struct block_device_operations *bdops = disk->fops; |
1068 | unsigned int events; |
1069 | |
1070 | events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE | |
1071 | DISK_EVENT_EJECT_REQUEST); |
1072 | if (!(events & DISK_EVENT_MEDIA_CHANGE)) |
1073 | return 0; |
1074 | |
1075 | flush_disk(bdev, true); |
1076 | if (bdops->revalidate_disk) |
1077 | bdops->revalidate_disk(bdev->bd_disk); |
1078 | return 1; |
1079 | } |
1080 | |
1081 | EXPORT_SYMBOL(check_disk_change); |
1082 | |
1083 | void bd_set_size(struct block_device *bdev, loff_t size) |
1084 | { |
1085 | unsigned bsize = bdev_logical_block_size(bdev); |
1086 | |
1087 | bdev->bd_inode->i_size = size; |
1088 | while (bsize < PAGE_CACHE_SIZE) { |
1089 | if (size & bsize) |
1090 | break; |
1091 | bsize <<= 1; |
1092 | } |
1093 | bdev->bd_block_size = bsize; |
1094 | bdev->bd_inode->i_blkbits = blksize_bits(bsize); |
1095 | } |
1096 | EXPORT_SYMBOL(bd_set_size); |
1097 | |
1098 | static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part); |
1099 | |
1100 | /* |
1101 | * bd_mutex locking: |
1102 | * |
1103 | * mutex_lock(part->bd_mutex) |
1104 | * mutex_lock_nested(whole->bd_mutex, 1) |
1105 | */ |
1106 | |
1107 | static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) |
1108 | { |
1109 | struct gendisk *disk; |
1110 | struct module *owner; |
1111 | int ret; |
1112 | int partno; |
1113 | int perm = 0; |
1114 | |
1115 | if (mode & FMODE_READ) |
1116 | perm |= MAY_READ; |
1117 | if (mode & FMODE_WRITE) |
1118 | perm |= MAY_WRITE; |
1119 | /* |
1120 | * hooks: /n/, see "layering violations". |
1121 | */ |
1122 | if (!for_part) { |
1123 | ret = devcgroup_inode_permission(bdev->bd_inode, perm); |
1124 | if (ret != 0) { |
1125 | bdput(bdev); |
1126 | return ret; |
1127 | } |
1128 | } |
1129 | |
1130 | restart: |
1131 | |
1132 | ret = -ENXIO; |
1133 | disk = get_gendisk(bdev->bd_dev, &partno); |
1134 | if (!disk) |
1135 | goto out; |
1136 | owner = disk->fops->owner; |
1137 | |
1138 | disk_block_events(disk); |
1139 | mutex_lock_nested(&bdev->bd_mutex, for_part); |
1140 | if (!bdev->bd_openers) { |
1141 | bdev->bd_disk = disk; |
1142 | bdev->bd_queue = disk->queue; |
1143 | bdev->bd_contains = bdev; |
1144 | if (!partno) { |
1145 | struct backing_dev_info *bdi; |
1146 | |
1147 | ret = -ENXIO; |
1148 | bdev->bd_part = disk_get_part(disk, partno); |
1149 | if (!bdev->bd_part) |
1150 | goto out_clear; |
1151 | |
1152 | ret = 0; |
1153 | if (disk->fops->open) { |
1154 | ret = disk->fops->open(bdev, mode); |
1155 | if (ret == -ERESTARTSYS) { |
1156 | /* Lost a race with 'disk' being |
1157 | * deleted, try again. |
1158 | * See md.c |
1159 | */ |
1160 | disk_put_part(bdev->bd_part); |
1161 | bdev->bd_part = NULL; |
1162 | bdev->bd_disk = NULL; |
1163 | bdev->bd_queue = NULL; |
1164 | mutex_unlock(&bdev->bd_mutex); |
1165 | disk_unblock_events(disk); |
1166 | put_disk(disk); |
1167 | module_put(owner); |
1168 | goto restart; |
1169 | } |
1170 | } |
1171 | |
1172 | if (!ret && !bdev->bd_openers) { |
1173 | bd_set_size(bdev,(loff_t)get_capacity(disk)<<9); |
1174 | bdi = blk_get_backing_dev_info(bdev); |
1175 | if (bdi == NULL) |
1176 | bdi = &default_backing_dev_info; |
1177 | bdev_inode_switch_bdi(bdev->bd_inode, bdi); |
1178 | } |
1179 | |
1180 | /* |
1181 | * If the device is invalidated, rescan partition |
1182 | * if open succeeded or failed with -ENOMEDIUM. |
1183 | * The latter is necessary to prevent ghost |
1184 | * partitions on a removed medium. |
1185 | */ |
1186 | if (bdev->bd_invalidated) { |
1187 | if (!ret) |
1188 | rescan_partitions(disk, bdev); |
1189 | else if (ret == -ENOMEDIUM) |
1190 | invalidate_partitions(disk, bdev); |
1191 | } |
1192 | if (ret) |
1193 | goto out_clear; |
1194 | } else { |
1195 | struct block_device *whole; |
1196 | whole = bdget_disk(disk, 0); |
1197 | ret = -ENOMEM; |
1198 | if (!whole) |
1199 | goto out_clear; |
1200 | BUG_ON(for_part); |
1201 | ret = __blkdev_get(whole, mode, 1); |
1202 | if (ret) |
1203 | goto out_clear; |
1204 | bdev->bd_contains = whole; |
1205 | bdev_inode_switch_bdi(bdev->bd_inode, |
1206 | whole->bd_inode->i_data.backing_dev_info); |
1207 | bdev->bd_part = disk_get_part(disk, partno); |
1208 | if (!(disk->flags & GENHD_FL_UP) || |
1209 | !bdev->bd_part || !bdev->bd_part->nr_sects) { |
1210 | ret = -ENXIO; |
1211 | goto out_clear; |
1212 | } |
1213 | bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9); |
1214 | } |
1215 | } else { |
1216 | if (bdev->bd_contains == bdev) { |
1217 | ret = 0; |
1218 | if (bdev->bd_disk->fops->open) |
1219 | ret = bdev->bd_disk->fops->open(bdev, mode); |
1220 | /* the same as first opener case, read comment there */ |
1221 | if (bdev->bd_invalidated) { |
1222 | if (!ret) |
1223 | rescan_partitions(bdev->bd_disk, bdev); |
1224 | else if (ret == -ENOMEDIUM) |
1225 | invalidate_partitions(bdev->bd_disk, bdev); |
1226 | } |
1227 | if (ret) |
1228 | goto out_unlock_bdev; |
1229 | } |
1230 | /* only one opener holds refs to the module and disk */ |
1231 | put_disk(disk); |
1232 | module_put(owner); |
1233 | } |
1234 | bdev->bd_openers++; |
1235 | if (for_part) |
1236 | bdev->bd_part_count++; |
1237 | mutex_unlock(&bdev->bd_mutex); |
1238 | disk_unblock_events(disk); |
1239 | return 0; |
1240 | |
1241 | out_clear: |
1242 | disk_put_part(bdev->bd_part); |
1243 | bdev->bd_disk = NULL; |
1244 | bdev->bd_part = NULL; |
1245 | bdev->bd_queue = NULL; |
1246 | bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info); |
1247 | if (bdev != bdev->bd_contains) |
1248 | __blkdev_put(bdev->bd_contains, mode, 1); |
1249 | bdev->bd_contains = NULL; |
1250 | out_unlock_bdev: |
1251 | mutex_unlock(&bdev->bd_mutex); |
1252 | disk_unblock_events(disk); |
1253 | put_disk(disk); |
1254 | module_put(owner); |
1255 | out: |
1256 | bdput(bdev); |
1257 | |
1258 | return ret; |
1259 | } |
1260 | |
1261 | /** |
1262 | * blkdev_get - open a block device |
1263 | * @bdev: block_device to open |
1264 | * @mode: FMODE_* mask |
1265 | * @holder: exclusive holder identifier |
1266 | * |
1267 | * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is |
1268 | * open with exclusive access. Specifying %FMODE_EXCL with %NULL |
1269 | * @holder is invalid. Exclusive opens may nest for the same @holder. |
1270 | * |
1271 | * On success, the reference count of @bdev is unchanged. On failure, |
1272 | * @bdev is put. |
1273 | * |
1274 | * CONTEXT: |
1275 | * Might sleep. |
1276 | * |
1277 | * RETURNS: |
1278 | * 0 on success, -errno on failure. |
1279 | */ |
1280 | int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) |
1281 | { |
1282 | struct block_device *whole = NULL; |
1283 | int res; |
1284 | |
1285 | WARN_ON_ONCE((mode & FMODE_EXCL) && !holder); |
1286 | |
1287 | if ((mode & FMODE_EXCL) && holder) { |
1288 | whole = bd_start_claiming(bdev, holder); |
1289 | if (IS_ERR(whole)) { |
1290 | bdput(bdev); |
1291 | return PTR_ERR(whole); |
1292 | } |
1293 | } |
1294 | |
1295 | res = __blkdev_get(bdev, mode, 0); |
1296 | |
1297 | if (whole) { |
1298 | struct gendisk *disk = whole->bd_disk; |
1299 | |
1300 | /* finish claiming */ |
1301 | mutex_lock(&bdev->bd_mutex); |
1302 | spin_lock(&bdev_lock); |
1303 | |
1304 | if (!res) { |
1305 | BUG_ON(!bd_may_claim(bdev, whole, holder)); |
1306 | /* |
1307 | * Note that for a whole device bd_holders |
1308 | * will be incremented twice, and bd_holder |
1309 | * will be set to bd_may_claim before being |
1310 | * set to holder |
1311 | */ |
1312 | whole->bd_holders++; |
1313 | whole->bd_holder = bd_may_claim; |
1314 | bdev->bd_holders++; |
1315 | bdev->bd_holder = holder; |
1316 | } |
1317 | |
1318 | /* tell others that we're done */ |
1319 | BUG_ON(whole->bd_claiming != holder); |
1320 | whole->bd_claiming = NULL; |
1321 | wake_up_bit(&whole->bd_claiming, 0); |
1322 | |
1323 | spin_unlock(&bdev_lock); |
1324 | |
1325 | /* |
1326 | * Block event polling for write claims if requested. Any |
1327 | * write holder makes the write_holder state stick until |
1328 | * all are released. This is good enough and tracking |
1329 | * individual writeable reference is too fragile given the |
1330 | * way @mode is used in blkdev_get/put(). |
1331 | */ |
1332 | if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder && |
1333 | (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { |
1334 | bdev->bd_write_holder = true; |
1335 | disk_block_events(disk); |
1336 | } |
1337 | |
1338 | mutex_unlock(&bdev->bd_mutex); |
1339 | bdput(whole); |
1340 | } |
1341 | |
1342 | return res; |
1343 | } |
1344 | EXPORT_SYMBOL(blkdev_get); |
1345 | |
1346 | /** |
1347 | * blkdev_get_by_path - open a block device by name |
1348 | * @path: path to the block device to open |
1349 | * @mode: FMODE_* mask |
1350 | * @holder: exclusive holder identifier |
1351 | * |
1352 | * Open the blockdevice described by the device file at @path. @mode |
1353 | * and @holder are identical to blkdev_get(). |
1354 | * |
1355 | * On success, the returned block_device has reference count of one. |
1356 | * |
1357 | * CONTEXT: |
1358 | * Might sleep. |
1359 | * |
1360 | * RETURNS: |
1361 | * Pointer to block_device on success, ERR_PTR(-errno) on failure. |
1362 | */ |
1363 | struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, |
1364 | void *holder) |
1365 | { |
1366 | struct block_device *bdev; |
1367 | int err; |
1368 | |
1369 | bdev = lookup_bdev(path); |
1370 | if (IS_ERR(bdev)) |
1371 | return bdev; |
1372 | |
1373 | err = blkdev_get(bdev, mode, holder); |
1374 | if (err) |
1375 | return ERR_PTR(err); |
1376 | |
1377 | if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) { |
1378 | blkdev_put(bdev, mode); |
1379 | return ERR_PTR(-EACCES); |
1380 | } |
1381 | |
1382 | return bdev; |
1383 | } |
1384 | EXPORT_SYMBOL(blkdev_get_by_path); |
1385 | |
1386 | /** |
1387 | * blkdev_get_by_dev - open a block device by device number |
1388 | * @dev: device number of block device to open |
1389 | * @mode: FMODE_* mask |
1390 | * @holder: exclusive holder identifier |
1391 | * |
1392 | * Open the blockdevice described by device number @dev. @mode and |
1393 | * @holder are identical to blkdev_get(). |
1394 | * |
1395 | * Use it ONLY if you really do not have anything better - i.e. when |
1396 | * you are behind a truly sucky interface and all you are given is a |
1397 | * device number. _Never_ to be used for internal purposes. If you |
1398 | * ever need it - reconsider your API. |
1399 | * |
1400 | * On success, the returned block_device has reference count of one. |
1401 | * |
1402 | * CONTEXT: |
1403 | * Might sleep. |
1404 | * |
1405 | * RETURNS: |
1406 | * Pointer to block_device on success, ERR_PTR(-errno) on failure. |
1407 | */ |
1408 | struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) |
1409 | { |
1410 | struct block_device *bdev; |
1411 | int err; |
1412 | |
1413 | bdev = bdget(dev); |
1414 | if (!bdev) |
1415 | return ERR_PTR(-ENOMEM); |
1416 | |
1417 | err = blkdev_get(bdev, mode, holder); |
1418 | if (err) |
1419 | return ERR_PTR(err); |
1420 | |
1421 | return bdev; |
1422 | } |
1423 | EXPORT_SYMBOL(blkdev_get_by_dev); |
1424 | |
1425 | static int blkdev_open(struct inode * inode, struct file * filp) |
1426 | { |
1427 | struct block_device *bdev; |
1428 | |
1429 | /* |
1430 | * Preserve backwards compatibility and allow large file access |
1431 | * even if userspace doesn't ask for it explicitly. Some mkfs |
1432 | * binary needs it. We might want to drop this workaround |
1433 | * during an unstable branch. |
1434 | */ |
1435 | filp->f_flags |= O_LARGEFILE; |
1436 | |
1437 | if (filp->f_flags & O_NDELAY) |
1438 | filp->f_mode |= FMODE_NDELAY; |
1439 | if (filp->f_flags & O_EXCL) |
1440 | filp->f_mode |= FMODE_EXCL; |
1441 | if ((filp->f_flags & O_ACCMODE) == 3) |
1442 | filp->f_mode |= FMODE_WRITE_IOCTL; |
1443 | |
1444 | bdev = bd_acquire(inode); |
1445 | if (bdev == NULL) |
1446 | return -ENOMEM; |
1447 | |
1448 | filp->f_mapping = bdev->bd_inode->i_mapping; |
1449 | |
1450 | return blkdev_get(bdev, filp->f_mode, filp); |
1451 | } |
1452 | |
1453 | static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) |
1454 | { |
1455 | int ret = 0; |
1456 | struct gendisk *disk = bdev->bd_disk; |
1457 | struct block_device *victim = NULL; |
1458 | |
1459 | mutex_lock_nested(&bdev->bd_mutex, for_part); |
1460 | if (for_part) |
1461 | bdev->bd_part_count--; |
1462 | |
1463 | if (!--bdev->bd_openers) { |
1464 | WARN_ON_ONCE(bdev->bd_holders); |
1465 | sync_blockdev(bdev); |
1466 | kill_bdev(bdev); |
1467 | /* ->release can cause the old bdi to disappear, |
1468 | * so must switch it out first |
1469 | */ |
1470 | bdev_inode_switch_bdi(bdev->bd_inode, |
1471 | &default_backing_dev_info); |
1472 | } |
1473 | if (bdev->bd_contains == bdev) { |
1474 | if (disk->fops->release) |
1475 | ret = disk->fops->release(disk, mode); |
1476 | } |
1477 | if (!bdev->bd_openers) { |
1478 | struct module *owner = disk->fops->owner; |
1479 | |
1480 | disk_put_part(bdev->bd_part); |
1481 | bdev->bd_part = NULL; |
1482 | bdev->bd_disk = NULL; |
1483 | if (bdev != bdev->bd_contains) |
1484 | victim = bdev->bd_contains; |
1485 | bdev->bd_contains = NULL; |
1486 | |
1487 | put_disk(disk); |
1488 | module_put(owner); |
1489 | } |
1490 | mutex_unlock(&bdev->bd_mutex); |
1491 | bdput(bdev); |
1492 | if (victim) |
1493 | __blkdev_put(victim, mode, 1); |
1494 | return ret; |
1495 | } |
1496 | |
1497 | int blkdev_put(struct block_device *bdev, fmode_t mode) |
1498 | { |
1499 | mutex_lock(&bdev->bd_mutex); |
1500 | |
1501 | if (mode & FMODE_EXCL) { |
1502 | bool bdev_free; |
1503 | |
1504 | /* |
1505 | * Release a claim on the device. The holder fields |
1506 | * are protected with bdev_lock. bd_mutex is to |
1507 | * synchronize disk_holder unlinking. |
1508 | */ |
1509 | spin_lock(&bdev_lock); |
1510 | |
1511 | WARN_ON_ONCE(--bdev->bd_holders < 0); |
1512 | WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0); |
1513 | |
1514 | /* bd_contains might point to self, check in a separate step */ |
1515 | if ((bdev_free = !bdev->bd_holders)) |
1516 | bdev->bd_holder = NULL; |
1517 | if (!bdev->bd_contains->bd_holders) |
1518 | bdev->bd_contains->bd_holder = NULL; |
1519 | |
1520 | spin_unlock(&bdev_lock); |
1521 | |
1522 | /* |
1523 | * If this was the last claim, remove holder link and |
1524 | * unblock evpoll if it was a write holder. |
1525 | */ |
1526 | if (bdev_free && bdev->bd_write_holder) { |
1527 | disk_unblock_events(bdev->bd_disk); |
1528 | bdev->bd_write_holder = false; |
1529 | } |
1530 | } |
1531 | |
1532 | /* |
1533 | * Trigger event checking and tell drivers to flush MEDIA_CHANGE |
1534 | * event. This is to ensure detection of media removal commanded |
1535 | * from userland - e.g. eject(1). |
1536 | */ |
1537 | disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE); |
1538 | |
1539 | mutex_unlock(&bdev->bd_mutex); |
1540 | |
1541 | return __blkdev_put(bdev, mode, 0); |
1542 | } |
1543 | EXPORT_SYMBOL(blkdev_put); |
1544 | |
1545 | static int blkdev_close(struct inode * inode, struct file * filp) |
1546 | { |
1547 | struct block_device *bdev = I_BDEV(filp->f_mapping->host); |
1548 | |
1549 | return blkdev_put(bdev, filp->f_mode); |
1550 | } |
1551 | |
1552 | static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg) |
1553 | { |
1554 | struct block_device *bdev = I_BDEV(file->f_mapping->host); |
1555 | fmode_t mode = file->f_mode; |
1556 | |
1557 | /* |
1558 | * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have |
1559 | * to updated it before every ioctl. |
1560 | */ |
1561 | if (file->f_flags & O_NDELAY) |
1562 | mode |= FMODE_NDELAY; |
1563 | else |
1564 | mode &= ~FMODE_NDELAY; |
1565 | |
1566 | return blkdev_ioctl(bdev, mode, cmd, arg); |
1567 | } |
1568 | |
1569 | /* |
1570 | * Write data to the block device. Only intended for the block device itself |
1571 | * and the raw driver which basically is a fake block device. |
1572 | * |
1573 | * Does not take i_mutex for the write and thus is not for general purpose |
1574 | * use. |
1575 | */ |
1576 | ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov, |
1577 | unsigned long nr_segs, loff_t pos) |
1578 | { |
1579 | struct file *file = iocb->ki_filp; |
1580 | ssize_t ret; |
1581 | |
1582 | BUG_ON(iocb->ki_pos != pos); |
1583 | |
1584 | ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); |
1585 | if (ret > 0 || ret == -EIOCBQUEUED) { |
1586 | ssize_t err; |
1587 | |
1588 | err = generic_write_sync(file, pos, ret); |
1589 | if (err < 0 && ret > 0) |
1590 | ret = err; |
1591 | } |
1592 | return ret; |
1593 | } |
1594 | EXPORT_SYMBOL_GPL(blkdev_aio_write); |
1595 | |
1596 | /* |
1597 | * Try to release a page associated with block device when the system |
1598 | * is under memory pressure. |
1599 | */ |
1600 | static int blkdev_releasepage(struct page *page, gfp_t wait) |
1601 | { |
1602 | struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super; |
1603 | |
1604 | if (super && super->s_op->bdev_try_to_free_page) |
1605 | return super->s_op->bdev_try_to_free_page(super, page, wait); |
1606 | |
1607 | return try_to_free_buffers(page); |
1608 | } |
1609 | |
1610 | static const struct address_space_operations def_blk_aops = { |
1611 | .readpage = blkdev_readpage, |
1612 | .writepage = blkdev_writepage, |
1613 | .write_begin = blkdev_write_begin, |
1614 | .write_end = blkdev_write_end, |
1615 | .writepages = generic_writepages, |
1616 | .releasepage = blkdev_releasepage, |
1617 | .direct_IO = blkdev_direct_IO, |
1618 | }; |
1619 | |
1620 | const struct file_operations def_blk_fops = { |
1621 | .open = blkdev_open, |
1622 | .release = blkdev_close, |
1623 | .llseek = block_llseek, |
1624 | .read = do_sync_read, |
1625 | .write = do_sync_write, |
1626 | .aio_read = generic_file_aio_read, |
1627 | .aio_write = blkdev_aio_write, |
1628 | .mmap = generic_file_mmap, |
1629 | .fsync = blkdev_fsync, |
1630 | .unlocked_ioctl = block_ioctl, |
1631 | #ifdef CONFIG_COMPAT |
1632 | .compat_ioctl = compat_blkdev_ioctl, |
1633 | #endif |
1634 | .splice_read = generic_file_splice_read, |
1635 | .splice_write = generic_file_splice_write, |
1636 | }; |
1637 | |
1638 | int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg) |
1639 | { |
1640 | int res; |
1641 | mm_segment_t old_fs = get_fs(); |
1642 | set_fs(KERNEL_DS); |
1643 | res = blkdev_ioctl(bdev, 0, cmd, arg); |
1644 | set_fs(old_fs); |
1645 | return res; |
1646 | } |
1647 | |
1648 | EXPORT_SYMBOL(ioctl_by_bdev); |
1649 | |
1650 | /** |
1651 | * lookup_bdev - lookup a struct block_device by name |
1652 | * @pathname: special file representing the block device |
1653 | * |
1654 | * Get a reference to the blockdevice at @pathname in the current |
1655 | * namespace if possible and return it. Return ERR_PTR(error) |
1656 | * otherwise. |
1657 | */ |
1658 | struct block_device *lookup_bdev(const char *pathname) |
1659 | { |
1660 | struct block_device *bdev; |
1661 | struct inode *inode; |
1662 | struct path path; |
1663 | int error; |
1664 | |
1665 | if (!pathname || !*pathname) |
1666 | return ERR_PTR(-EINVAL); |
1667 | |
1668 | error = kern_path(pathname, LOOKUP_FOLLOW, &path); |
1669 | if (error) |
1670 | return ERR_PTR(error); |
1671 | |
1672 | inode = path.dentry->d_inode; |
1673 | error = -ENOTBLK; |
1674 | if (!S_ISBLK(inode->i_mode)) |
1675 | goto fail; |
1676 | error = -EACCES; |
1677 | if (path.mnt->mnt_flags & MNT_NODEV) |
1678 | goto fail; |
1679 | error = -ENOMEM; |
1680 | bdev = bd_acquire(inode); |
1681 | if (!bdev) |
1682 | goto fail; |
1683 | out: |
1684 | path_put(&path); |
1685 | return bdev; |
1686 | fail: |
1687 | bdev = ERR_PTR(error); |
1688 | goto out; |
1689 | } |
1690 | EXPORT_SYMBOL(lookup_bdev); |
1691 | |
1692 | int __invalidate_device(struct block_device *bdev, bool kill_dirty) |
1693 | { |
1694 | struct super_block *sb = get_super(bdev); |
1695 | int res = 0; |
1696 | |
1697 | if (sb) { |
1698 | /* |
1699 | * no need to lock the super, get_super holds the |
1700 | * read mutex so the filesystem cannot go away |
1701 | * under us (->put_super runs with the write lock |
1702 | * hold). |
1703 | */ |
1704 | shrink_dcache_sb(sb); |
1705 | res = invalidate_inodes(sb, kill_dirty); |
1706 | drop_super(sb); |
1707 | } |
1708 | invalidate_bdev(bdev); |
1709 | return res; |
1710 | } |
1711 | EXPORT_SYMBOL(__invalidate_device); |
1712 |
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