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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 <asm/uaccess.h> |
31 | #include "internal.h" |
32 | |
33 | struct bdev_inode { |
34 | struct block_device bdev; |
35 | struct inode vfs_inode; |
36 | }; |
37 | |
38 | static const struct address_space_operations def_blk_aops; |
39 | |
40 | static inline struct bdev_inode *BDEV_I(struct inode *inode) |
41 | { |
42 | return container_of(inode, struct bdev_inode, vfs_inode); |
43 | } |
44 | |
45 | inline struct block_device *I_BDEV(struct inode *inode) |
46 | { |
47 | return &BDEV_I(inode)->bdev; |
48 | } |
49 | EXPORT_SYMBOL(I_BDEV); |
50 | |
51 | /* |
52 | * Move the inode from its current bdi to a new bdi. If the inode is dirty we |
53 | * need to move it onto the dirty list of @dst so that the inode is always on |
54 | * the right list. |
55 | */ |
56 | static void bdev_inode_switch_bdi(struct inode *inode, |
57 | struct backing_dev_info *dst) |
58 | { |
59 | struct backing_dev_info *old = inode->i_data.backing_dev_info; |
60 | |
61 | if (unlikely(dst == old)) /* deadlock avoidance */ |
62 | return; |
63 | bdi_lock_two(&old->wb, &dst->wb); |
64 | spin_lock(&inode->i_lock); |
65 | inode->i_data.backing_dev_info = dst; |
66 | if (inode->i_state & I_DIRTY) |
67 | list_move(&inode->i_wb_list, &dst->wb.b_dirty); |
68 | spin_unlock(&inode->i_lock); |
69 | spin_unlock(&old->wb.list_lock); |
70 | spin_unlock(&dst->wb.list_lock); |
71 | } |
72 | |
73 | sector_t blkdev_max_block(struct block_device *bdev) |
74 | { |
75 | sector_t retval = ~((sector_t)0); |
76 | loff_t sz = i_size_read(bdev->bd_inode); |
77 | |
78 | if (sz) { |
79 | unsigned int size = block_size(bdev); |
80 | unsigned int sizebits = blksize_bits(size); |
81 | retval = (sz >> sizebits); |
82 | } |
83 | return retval; |
84 | } |
85 | |
86 | /* Kill _all_ buffers and pagecache , dirty or not.. */ |
87 | void kill_bdev(struct block_device *bdev) |
88 | { |
89 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
90 | |
91 | if (mapping->nrpages == 0) |
92 | return; |
93 | |
94 | invalidate_bh_lrus(); |
95 | truncate_inode_pages(mapping, 0); |
96 | } |
97 | EXPORT_SYMBOL(kill_bdev); |
98 | |
99 | /* Invalidate clean unused buffers and pagecache. */ |
100 | void invalidate_bdev(struct block_device *bdev) |
101 | { |
102 | struct address_space *mapping = bdev->bd_inode->i_mapping; |
103 | |
104 | if (mapping->nrpages == 0) |
105 | return; |
106 | |
107 | invalidate_bh_lrus(); |
108 | lru_add_drain_all(); /* make sure all lru add caches are flushed */ |
109 | invalidate_mapping_pages(mapping, 0, -1); |
110 | /* 99% of the time, we don't need to flush the cleancache on the bdev. |
111 | * But, for the strange corners, lets be cautious |
112 | */ |
113 | cleancache_invalidate_inode(mapping); |
114 | } |
115 | EXPORT_SYMBOL(invalidate_bdev); |
116 | |
117 | int set_blocksize(struct block_device *bdev, int size) |
118 | { |
119 | /* Size must be a power of two, and between 512 and PAGE_SIZE */ |
120 | if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size)) |
121 | return -EINVAL; |
122 | |
123 | /* Size cannot be smaller than the size supported by the device */ |
124 | if (size < bdev_logical_block_size(bdev)) |
125 | return -EINVAL; |
126 | |
127 | /* Don't change the size if it is same as current */ |
128 | if (bdev->bd_block_size != size) { |
129 | sync_blockdev(bdev); |
130 | bdev->bd_block_size = size; |
131 | bdev->bd_inode->i_blkbits = blksize_bits(size); |
132 | kill_bdev(bdev); |
133 | } |
134 | return 0; |
135 | } |
136 | |
137 | EXPORT_SYMBOL(set_blocksize); |
138 | |
139 | int sb_set_blocksize(struct super_block *sb, int size) |
140 | { |
141 | if (set_blocksize(sb->s_bdev, size)) |
142 | return 0; |
143 | /* If we get here, we know size is power of two |
144 | * and it's value is between 512 and PAGE_SIZE */ |
145 | sb->s_blocksize = size; |
146 | sb->s_blocksize_bits = blksize_bits(size); |
147 | return sb->s_blocksize; |
148 | } |
149 | |
150 | EXPORT_SYMBOL(sb_set_blocksize); |
151 | |
152 | int sb_min_blocksize(struct super_block *sb, int size) |
153 | { |
154 | int minsize = bdev_logical_block_size(sb->s_bdev); |
155 | if (size < minsize) |
156 | size = minsize; |
157 | return sb_set_blocksize(sb, size); |
158 | } |
159 | |
160 | EXPORT_SYMBOL(sb_min_blocksize); |
161 | |
162 | static int |
163 | blkdev_get_block(struct inode *inode, sector_t iblock, |
164 | struct buffer_head *bh, int create) |
165 | { |
166 | if (iblock >= blkdev_max_block(I_BDEV(inode))) { |
167 | if (create) |
168 | return -EIO; |
169 | |
170 | /* |
171 | * for reads, we're just trying to fill a partial page. |
172 | * return a hole, they will have to call get_block again |
173 | * before they can fill it, and they will get -EIO at that |
174 | * time |
175 | */ |
176 | return 0; |
177 | } |
178 | bh->b_bdev = I_BDEV(inode); |
179 | bh->b_blocknr = iblock; |
180 | set_buffer_mapped(bh); |
181 | return 0; |
182 | } |
183 | |
184 | static int |
185 | blkdev_get_blocks(struct inode *inode, sector_t iblock, |
186 | struct buffer_head *bh, int create) |
187 | { |
188 | sector_t end_block = blkdev_max_block(I_BDEV(inode)); |
189 | unsigned long max_blocks = bh->b_size >> inode->i_blkbits; |
190 | |
191 | if ((iblock + max_blocks) > end_block) { |
192 | max_blocks = end_block - iblock; |
193 | if ((long)max_blocks <= 0) { |
194 | if (create) |
195 | return -EIO; /* write fully beyond EOF */ |
196 | /* |
197 | * It is a read which is fully beyond EOF. We return |
198 | * a !buffer_mapped buffer |
199 | */ |
200 | max_blocks = 0; |
201 | } |
202 | } |
203 | |
204 | bh->b_bdev = I_BDEV(inode); |
205 | bh->b_blocknr = iblock; |
206 | bh->b_size = max_blocks << inode->i_blkbits; |
207 | if (max_blocks) |
208 | set_buffer_mapped(bh); |
209 | return 0; |
210 | } |
211 | |
212 | static ssize_t |
213 | blkdev_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov, |
214 | loff_t offset, unsigned long nr_segs) |
215 | { |
216 | struct file *file = iocb->ki_filp; |
217 | struct inode *inode = file->f_mapping->host; |
218 | |
219 | return __blockdev_direct_IO(rw, iocb, inode, I_BDEV(inode), iov, offset, |
220 | nr_segs, blkdev_get_blocks, NULL, NULL, 0); |
221 | } |
222 | |
223 | int __sync_blockdev(struct block_device *bdev, int wait) |
224 | { |
225 | if (!bdev) |
226 | return 0; |
227 | if (!wait) |
228 | return filemap_flush(bdev->bd_inode->i_mapping); |
229 | return filemap_write_and_wait(bdev->bd_inode->i_mapping); |
230 | } |
231 | |
232 | /* |
233 | * Write out and wait upon all the dirty data associated with a block |
234 | * device via its mapping. Does not take the superblock lock. |
235 | */ |
236 | int sync_blockdev(struct block_device *bdev) |
237 | { |
238 | return __sync_blockdev(bdev, 1); |
239 | } |
240 | EXPORT_SYMBOL(sync_blockdev); |
241 | |
242 | /* |
243 | * Write out and wait upon all dirty data associated with this |
244 | * device. Filesystem data as well as the underlying block |
245 | * device. Takes the superblock lock. |
246 | */ |
247 | int fsync_bdev(struct block_device *bdev) |
248 | { |
249 | struct super_block *sb = get_super(bdev); |
250 | if (sb) { |
251 | int res = sync_filesystem(sb); |
252 | drop_super(sb); |
253 | return res; |
254 | } |
255 | return sync_blockdev(bdev); |
256 | } |
257 | EXPORT_SYMBOL(fsync_bdev); |
258 | |
259 | /** |
260 | * freeze_bdev -- lock a filesystem and force it into a consistent state |
261 | * @bdev: blockdevice to lock |
262 | * |
263 | * If a superblock is found on this device, we take the s_umount semaphore |
264 | * on it to make sure nobody unmounts until the snapshot creation is done. |
265 | * The reference counter (bd_fsfreeze_count) guarantees that only the last |
266 | * unfreeze process can unfreeze the frozen filesystem actually when multiple |
267 | * freeze requests arrive simultaneously. It counts up in freeze_bdev() and |
268 | * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze |
269 | * actually. |
270 | */ |
271 | struct super_block *freeze_bdev(struct block_device *bdev) |
272 | { |
273 | struct super_block *sb; |
274 | int error = 0; |
275 | |
276 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
277 | if (++bdev->bd_fsfreeze_count > 1) { |
278 | /* |
279 | * We don't even need to grab a reference - the first call |
280 | * to freeze_bdev grab an active reference and only the last |
281 | * thaw_bdev drops it. |
282 | */ |
283 | sb = get_super(bdev); |
284 | drop_super(sb); |
285 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
286 | return sb; |
287 | } |
288 | |
289 | sb = get_active_super(bdev); |
290 | if (!sb) |
291 | goto out; |
292 | error = freeze_super(sb); |
293 | if (error) { |
294 | deactivate_super(sb); |
295 | bdev->bd_fsfreeze_count--; |
296 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
297 | return ERR_PTR(error); |
298 | } |
299 | deactivate_super(sb); |
300 | out: |
301 | sync_blockdev(bdev); |
302 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
303 | return sb; /* thaw_bdev releases s->s_umount */ |
304 | } |
305 | EXPORT_SYMBOL(freeze_bdev); |
306 | |
307 | /** |
308 | * thaw_bdev -- unlock filesystem |
309 | * @bdev: blockdevice to unlock |
310 | * @sb: associated superblock |
311 | * |
312 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). |
313 | */ |
314 | int thaw_bdev(struct block_device *bdev, struct super_block *sb) |
315 | { |
316 | int error = -EINVAL; |
317 | |
318 | mutex_lock(&bdev->bd_fsfreeze_mutex); |
319 | if (!bdev->bd_fsfreeze_count) |
320 | goto out; |
321 | |
322 | error = 0; |
323 | if (--bdev->bd_fsfreeze_count > 0) |
324 | goto out; |
325 | |
326 | if (!sb) |
327 | goto out; |
328 | |
329 | error = thaw_super(sb); |
330 | if (error) { |
331 | bdev->bd_fsfreeze_count++; |
332 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
333 | return error; |
334 | } |
335 | out: |
336 | mutex_unlock(&bdev->bd_fsfreeze_mutex); |
337 | return 0; |
338 | } |
339 | EXPORT_SYMBOL(thaw_bdev); |
340 | |
341 | static int blkdev_writepage(struct page *page, struct writeback_control *wbc) |
342 | { |
343 | return block_write_full_page(page, blkdev_get_block, wbc); |
344 | } |
345 | |
346 | static int blkdev_readpage(struct file * file, struct page * page) |
347 | { |
348 | return block_read_full_page(page, blkdev_get_block); |
349 | } |
350 | |
351 | static int blkdev_write_begin(struct file *file, struct address_space *mapping, |
352 | loff_t pos, unsigned len, unsigned flags, |
353 | struct page **pagep, void **fsdata) |
354 | { |
355 | return block_write_begin(mapping, pos, len, flags, pagep, |
356 | blkdev_get_block); |
357 | } |
358 | |
359 | static int blkdev_write_end(struct file *file, struct address_space *mapping, |
360 | loff_t pos, unsigned len, unsigned copied, |
361 | struct page *page, void *fsdata) |
362 | { |
363 | int ret; |
364 | ret = block_write_end(file, mapping, pos, len, copied, page, fsdata); |
365 | |
366 | unlock_page(page); |
367 | page_cache_release(page); |
368 | |
369 | return ret; |
370 | } |
371 | |
372 | /* |
373 | * private llseek: |
374 | * for a block special file file->f_path.dentry->d_inode->i_size is zero |
375 | * so we compute the size by hand (just as in block_read/write above) |
376 | */ |
377 | static loff_t block_llseek(struct file *file, loff_t offset, int origin) |
378 | { |
379 | struct inode *bd_inode = file->f_mapping->host; |
380 | loff_t size; |
381 | loff_t retval; |
382 | |
383 | mutex_lock(&bd_inode->i_mutex); |
384 | size = i_size_read(bd_inode); |
385 | |
386 | retval = -EINVAL; |
387 | switch (origin) { |
388 | case SEEK_END: |
389 | offset += size; |
390 | break; |
391 | case SEEK_CUR: |
392 | offset += file->f_pos; |
393 | case SEEK_SET: |
394 | break; |
395 | default: |
396 | goto out; |
397 | } |
398 | if (offset >= 0 && offset <= size) { |
399 | if (offset != file->f_pos) { |
400 | file->f_pos = offset; |
401 | } |
402 | retval = offset; |
403 | } |
404 | out: |
405 | mutex_unlock(&bd_inode->i_mutex); |
406 | return retval; |
407 | } |
408 | |
409 | int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) |
410 | { |
411 | struct inode *bd_inode = filp->f_mapping->host; |
412 | struct block_device *bdev = I_BDEV(bd_inode); |
413 | int error; |
414 | |
415 | error = filemap_write_and_wait_range(filp->f_mapping, start, end); |
416 | if (error) |
417 | return error; |
418 | |
419 | /* |
420 | * There is no need to serialise calls to blkdev_issue_flush with |
421 | * i_mutex and doing so causes performance issues with concurrent |
422 | * O_SYNC writers to a block device. |
423 | */ |
424 | error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL); |
425 | if (error == -EOPNOTSUPP) |
426 | error = 0; |
427 | |
428 | return error; |
429 | } |
430 | EXPORT_SYMBOL(blkdev_fsync); |
431 | |
432 | /* |
433 | * pseudo-fs |
434 | */ |
435 | |
436 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock); |
437 | static struct kmem_cache * bdev_cachep __read_mostly; |
438 | |
439 | static struct inode *bdev_alloc_inode(struct super_block *sb) |
440 | { |
441 | struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL); |
442 | if (!ei) |
443 | return NULL; |
444 | return &ei->vfs_inode; |
445 | } |
446 | |
447 | static void bdev_i_callback(struct rcu_head *head) |
448 | { |
449 | struct inode *inode = container_of(head, struct inode, i_rcu); |
450 | struct bdev_inode *bdi = BDEV_I(inode); |
451 | |
452 | kmem_cache_free(bdev_cachep, bdi); |
453 | } |
454 | |
455 | static void bdev_destroy_inode(struct inode *inode) |
456 | { |
457 | call_rcu(&inode->i_rcu, bdev_i_callback); |
458 | } |
459 | |
460 | static void init_once(void *foo) |
461 | { |
462 | struct bdev_inode *ei = (struct bdev_inode *) foo; |
463 | struct block_device *bdev = &ei->bdev; |
464 | |
465 | memset(bdev, 0, sizeof(*bdev)); |
466 | mutex_init(&bdev->bd_mutex); |
467 | INIT_LIST_HEAD(&bdev->bd_inodes); |
468 | INIT_LIST_HEAD(&bdev->bd_list); |
469 | #ifdef CONFIG_SYSFS |
470 | INIT_LIST_HEAD(&bdev->bd_holder_disks); |
471 | #endif |
472 | inode_init_once(&ei->vfs_inode); |
473 | /* Initialize mutex for freeze. */ |
474 | mutex_init(&bdev->bd_fsfreeze_mutex); |
475 | } |
476 | |
477 | static inline void __bd_forget(struct inode *inode) |
478 | { |
479 | list_del_init(&inode->i_devices); |
480 | inode->i_bdev = NULL; |
481 | inode->i_mapping = &inode->i_data; |
482 | } |
483 | |
484 | static void bdev_evict_inode(struct inode *inode) |
485 | { |
486 | struct block_device *bdev = &BDEV_I(inode)->bdev; |
487 | struct list_head *p; |
488 | truncate_inode_pages(&inode->i_data, 0); |
489 | invalidate_inode_buffers(inode); /* is it needed here? */ |
490 | clear_inode(inode); |
491 | spin_lock(&bdev_lock); |
492 | while ( (p = bdev->bd_inodes.next) != &bdev->bd_inodes ) { |
493 | __bd_forget(list_entry(p, struct inode, i_devices)); |
494 | } |
495 | list_del_init(&bdev->bd_list); |
496 | spin_unlock(&bdev_lock); |
497 | } |
498 | |
499 | static const struct super_operations bdev_sops = { |
500 | .statfs = simple_statfs, |
501 | .alloc_inode = bdev_alloc_inode, |
502 | .destroy_inode = bdev_destroy_inode, |
503 | .drop_inode = generic_delete_inode, |
504 | .evict_inode = bdev_evict_inode, |
505 | }; |
506 | |
507 | static struct dentry *bd_mount(struct file_system_type *fs_type, |
508 | int flags, const char *dev_name, void *data) |
509 | { |
510 | return mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC); |
511 | } |
512 | |
513 | static struct file_system_type bd_type = { |
514 | .name = "bdev", |
515 | .mount = bd_mount, |
516 | .kill_sb = kill_anon_super, |
517 | }; |
518 | |
519 | static struct super_block *blockdev_superblock __read_mostly; |
520 | |
521 | void __init bdev_cache_init(void) |
522 | { |
523 | int err; |
524 | static struct vfsmount *bd_mnt; |
525 | |
526 | bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode), |
527 | 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| |
528 | SLAB_MEM_SPREAD|SLAB_PANIC), |
529 | init_once); |
530 | err = register_filesystem(&bd_type); |
531 | if (err) |
532 | panic("Cannot register bdev pseudo-fs"); |
533 | bd_mnt = kern_mount(&bd_type); |
534 | if (IS_ERR(bd_mnt)) |
535 | panic("Cannot create bdev pseudo-fs"); |
536 | blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ |
537 | } |
538 | |
539 | /* |
540 | * Most likely _very_ bad one - but then it's hardly critical for small |
541 | * /dev and can be fixed when somebody will need really large one. |
542 | * Keep in mind that it will be fed through icache hash function too. |
543 | */ |
544 | static inline unsigned long hash(dev_t dev) |
545 | { |
546 | return MAJOR(dev)+MINOR(dev); |
547 | } |
548 | |
549 | static int bdev_test(struct inode *inode, void *data) |
550 | { |
551 | return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data; |
552 | } |
553 | |
554 | static int bdev_set(struct inode *inode, void *data) |
555 | { |
556 | BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data; |
557 | return 0; |
558 | } |
559 | |
560 | static LIST_HEAD(all_bdevs); |
561 | |
562 | struct block_device *bdget(dev_t dev) |
563 | { |
564 | struct block_device *bdev; |
565 | struct inode *inode; |
566 | |
567 | inode = iget5_locked(blockdev_superblock, hash(dev), |
568 | bdev_test, bdev_set, &dev); |
569 | |
570 | if (!inode) |
571 | return NULL; |
572 | |
573 | bdev = &BDEV_I(inode)->bdev; |
574 | |
575 | if (inode->i_state & I_NEW) { |
576 | bdev->bd_contains = NULL; |
577 | bdev->bd_super = NULL; |
578 | bdev->bd_inode = inode; |
579 | bdev->bd_block_size = (1 << inode->i_blkbits); |
580 | bdev->bd_part_count = 0; |
581 | bdev->bd_invalidated = 0; |
582 | inode->i_mode = S_IFBLK; |
583 | inode->i_rdev = dev; |
584 | inode->i_bdev = bdev; |
585 | inode->i_data.a_ops = &def_blk_aops; |
586 | mapping_set_gfp_mask(&inode->i_data, GFP_USER); |
587 | inode->i_data.backing_dev_info = &default_backing_dev_info; |
588 | spin_lock(&bdev_lock); |
589 | list_add(&bdev->bd_list, &all_bdevs); |
590 | spin_unlock(&bdev_lock); |
591 | unlock_new_inode(inode); |
592 | } |
593 | return bdev; |
594 | } |
595 | |
596 | EXPORT_SYMBOL(bdget); |
597 | |
598 | /** |
599 | * bdgrab -- Grab a reference to an already referenced block device |
600 | * @bdev: Block device to grab a reference to. |
601 | */ |
602 | struct block_device *bdgrab(struct block_device *bdev) |
603 | { |
604 | ihold(bdev->bd_inode); |
605 | return bdev; |
606 | } |
607 | |
608 | long nr_blockdev_pages(void) |
609 | { |
610 | struct block_device *bdev; |
611 | long ret = 0; |
612 | spin_lock(&bdev_lock); |
613 | list_for_each_entry(bdev, &all_bdevs, bd_list) { |
614 | ret += bdev->bd_inode->i_mapping->nrpages; |
615 | } |
616 | spin_unlock(&bdev_lock); |
617 | return ret; |
618 | } |
619 | |
620 | void bdput(struct block_device *bdev) |
621 | { |
622 | iput(bdev->bd_inode); |
623 | } |
624 | |
625 | EXPORT_SYMBOL(bdput); |
626 | |
627 | static struct block_device *bd_acquire(struct inode *inode) |
628 | { |
629 | struct block_device *bdev; |
630 | |
631 | spin_lock(&bdev_lock); |
632 | bdev = inode->i_bdev; |
633 | if (bdev) { |
634 | ihold(bdev->bd_inode); |
635 | spin_unlock(&bdev_lock); |
636 | return bdev; |
637 | } |
638 | spin_unlock(&bdev_lock); |
639 | |
640 | bdev = bdget(inode->i_rdev); |
641 | if (bdev) { |
642 | spin_lock(&bdev_lock); |
643 | if (!inode->i_bdev) { |
644 | /* |
645 | * We take an additional reference to bd_inode, |
646 | * and it's released in clear_inode() of inode. |
647 | * So, we can access it via ->i_mapping always |
648 | * without igrab(). |
649 | */ |
650 | ihold(bdev->bd_inode); |
651 | inode->i_bdev = bdev; |
652 | inode->i_mapping = bdev->bd_inode->i_mapping; |
653 | list_add(&inode->i_devices, &bdev->bd_inodes); |
654 | } |
655 | spin_unlock(&bdev_lock); |
656 | } |
657 | return bdev; |
658 | } |
659 | |
660 | static inline int sb_is_blkdev_sb(struct super_block *sb) |
661 | { |
662 | return sb == blockdev_superblock; |
663 | } |
664 | |
665 | /* Call when you free inode */ |
666 | |
667 | void bd_forget(struct inode *inode) |
668 | { |
669 | struct block_device *bdev = NULL; |
670 | |
671 | spin_lock(&bdev_lock); |
672 | if (inode->i_bdev) { |
673 | if (!sb_is_blkdev_sb(inode->i_sb)) |
674 | bdev = inode->i_bdev; |
675 | __bd_forget(inode); |
676 | } |
677 | spin_unlock(&bdev_lock); |
678 | |
679 | if (bdev) |
680 | iput(bdev->bd_inode); |
681 | } |
682 | |
683 | /** |
684 | * bd_may_claim - test whether a block device can be claimed |
685 | * @bdev: block device of interest |
686 | * @whole: whole block device containing @bdev, may equal @bdev |
687 | * @holder: holder trying to claim @bdev |
688 | * |
689 | * Test whether @bdev can be claimed by @holder. |
690 | * |
691 | * CONTEXT: |
692 | * spin_lock(&bdev_lock). |
693 | * |
694 | * RETURNS: |
695 | * %true if @bdev can be claimed, %false otherwise. |
696 | */ |
697 | static bool bd_may_claim(struct block_device *bdev, struct block_device *whole, |
698 | void *holder) |
699 | { |
700 | if (bdev->bd_holder == holder) |
701 | return true; /* already a holder */ |
702 | else if (bdev->bd_holder != NULL) |
703 | return false; /* held by someone else */ |
704 | else if (bdev->bd_contains == bdev) |
705 | return true; /* is a whole device which isn't held */ |
706 | |
707 | else if (whole->bd_holder == bd_may_claim) |
708 | return true; /* is a partition of a device that is being partitioned */ |
709 | else if (whole->bd_holder != NULL) |
710 | return false; /* is a partition of a held device */ |
711 | else |
712 | return true; /* is a partition of an un-held device */ |
713 | } |
714 | |
715 | /** |
716 | * bd_prepare_to_claim - prepare to claim a block device |
717 | * @bdev: block device of interest |
718 | * @whole: the whole device containing @bdev, may equal @bdev |
719 | * @holder: holder trying to claim @bdev |
720 | * |
721 | * Prepare to claim @bdev. This function fails if @bdev is already |
722 | * claimed by another holder and waits if another claiming is in |
723 | * progress. This function doesn't actually claim. On successful |
724 | * return, the caller has ownership of bd_claiming and bd_holder[s]. |
725 | * |
726 | * CONTEXT: |
727 | * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab |
728 | * it multiple times. |
729 | * |
730 | * RETURNS: |
731 | * 0 if @bdev can be claimed, -EBUSY otherwise. |
732 | */ |
733 | static int bd_prepare_to_claim(struct block_device *bdev, |
734 | struct block_device *whole, void *holder) |
735 | { |
736 | retry: |
737 | /* if someone else claimed, fail */ |
738 | if (!bd_may_claim(bdev, whole, holder)) |
739 | return -EBUSY; |
740 | |
741 | /* if claiming is already in progress, wait for it to finish */ |
742 | if (whole->bd_claiming) { |
743 | wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0); |
744 | DEFINE_WAIT(wait); |
745 | |
746 | prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); |
747 | spin_unlock(&bdev_lock); |
748 | schedule(); |
749 | finish_wait(wq, &wait); |
750 | spin_lock(&bdev_lock); |
751 | goto retry; |
752 | } |
753 | |
754 | /* yay, all mine */ |
755 | return 0; |
756 | } |
757 | |
758 | /** |
759 | * bd_start_claiming - start claiming a block device |
760 | * @bdev: block device of interest |
761 | * @holder: holder trying to claim @bdev |
762 | * |
763 | * @bdev is about to be opened exclusively. Check @bdev can be opened |
764 | * exclusively and mark that an exclusive open is in progress. Each |
765 | * successful call to this function must be matched with a call to |
766 | * either bd_finish_claiming() or bd_abort_claiming() (which do not |
767 | * fail). |
768 | * |
769 | * This function is used to gain exclusive access to the block device |
770 | * without actually causing other exclusive open attempts to fail. It |
771 | * should be used when the open sequence itself requires exclusive |
772 | * access but may subsequently fail. |
773 | * |
774 | * CONTEXT: |
775 | * Might sleep. |
776 | * |
777 | * RETURNS: |
778 | * Pointer to the block device containing @bdev on success, ERR_PTR() |
779 | * value on failure. |
780 | */ |
781 | static struct block_device *bd_start_claiming(struct block_device *bdev, |
782 | void *holder) |
783 | { |
784 | struct gendisk *disk; |
785 | struct block_device *whole; |
786 | int partno, err; |
787 | |
788 | might_sleep(); |
789 | |
790 | /* |
791 | * @bdev might not have been initialized properly yet, look up |
792 | * and grab the outer block device the hard way. |
793 | */ |
794 | disk = get_gendisk(bdev->bd_dev, &partno); |
795 | if (!disk) |
796 | return ERR_PTR(-ENXIO); |
797 | |
798 | /* |
799 | * Normally, @bdev should equal what's returned from bdget_disk() |
800 | * if partno is 0; however, some drivers (floppy) use multiple |
801 | * bdev's for the same physical device and @bdev may be one of the |
802 | * aliases. Keep @bdev if partno is 0. This means claimer |
803 | * tracking is broken for those devices but it has always been that |
804 | * way. |
805 | */ |
806 | if (partno) |
807 | whole = bdget_disk(disk, 0); |
808 | else |
809 | whole = bdgrab(bdev); |
810 | |
811 | module_put(disk->fops->owner); |
812 | put_disk(disk); |
813 | if (!whole) |
814 | return ERR_PTR(-ENOMEM); |
815 | |
816 | /* prepare to claim, if successful, mark claiming in progress */ |
817 | spin_lock(&bdev_lock); |
818 | |
819 | err = bd_prepare_to_claim(bdev, whole, holder); |
820 | if (err == 0) { |
821 | whole->bd_claiming = holder; |
822 | spin_unlock(&bdev_lock); |
823 | return whole; |
824 | } else { |
825 | spin_unlock(&bdev_lock); |
826 | bdput(whole); |
827 | return ERR_PTR(err); |
828 | } |
829 | } |
830 | |
831 | #ifdef CONFIG_SYSFS |
832 | struct bd_holder_disk { |
833 | struct list_head list; |
834 | struct gendisk *disk; |
835 | int refcnt; |
836 | }; |
837 | |
838 | static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev, |
839 | struct gendisk *disk) |
840 | { |
841 | struct bd_holder_disk *holder; |
842 | |
843 | list_for_each_entry(holder, &bdev->bd_holder_disks, list) |
844 | if (holder->disk == disk) |
845 | return holder; |
846 | return NULL; |
847 | } |
848 | |
849 | static int add_symlink(struct kobject *from, struct kobject *to) |
850 | { |
851 | return sysfs_create_link(from, to, kobject_name(to)); |
852 | } |
853 | |
854 | static void del_symlink(struct kobject *from, struct kobject *to) |
855 | { |
856 | sysfs_remove_link(from, kobject_name(to)); |
857 | } |
858 | |
859 | /** |
860 | * bd_link_disk_holder - create symlinks between holding disk and slave bdev |
861 | * @bdev: the claimed slave bdev |
862 | * @disk: the holding disk |
863 | * |
864 | * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. |
865 | * |
866 | * This functions creates the following sysfs symlinks. |
867 | * |
868 | * - from "slaves" directory of the holder @disk to the claimed @bdev |
869 | * - from "holders" directory of the @bdev to the holder @disk |
870 | * |
871 | * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is |
872 | * passed to bd_link_disk_holder(), then: |
873 | * |
874 | * /sys/block/dm-0/slaves/sda --> /sys/block/sda |
875 | * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0 |
876 | * |
877 | * The caller must have claimed @bdev before calling this function and |
878 | * ensure that both @bdev and @disk are valid during the creation and |
879 | * lifetime of these symlinks. |
880 | * |
881 | * CONTEXT: |
882 | * Might sleep. |
883 | * |
884 | * RETURNS: |
885 | * 0 on success, -errno on failure. |
886 | */ |
887 | int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) |
888 | { |
889 | struct bd_holder_disk *holder; |
890 | int ret = 0; |
891 | |
892 | mutex_lock(&bdev->bd_mutex); |
893 | |
894 | WARN_ON_ONCE(!bdev->bd_holder); |
895 | |
896 | /* FIXME: remove the following once add_disk() handles errors */ |
897 | if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir)) |
898 | goto out_unlock; |
899 | |
900 | holder = bd_find_holder_disk(bdev, disk); |
901 | if (holder) { |
902 | holder->refcnt++; |
903 | goto out_unlock; |
904 | } |
905 | |
906 | holder = kzalloc(sizeof(*holder), GFP_KERNEL); |
907 | if (!holder) { |
908 | ret = -ENOMEM; |
909 | goto out_unlock; |
910 | } |
911 | |
912 | INIT_LIST_HEAD(&holder->list); |
913 | holder->disk = disk; |
914 | holder->refcnt = 1; |
915 | |
916 | ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
917 | if (ret) |
918 | goto out_free; |
919 | |
920 | ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); |
921 | if (ret) |
922 | goto out_del; |
923 | /* |
924 | * bdev could be deleted beneath us which would implicitly destroy |
925 | * the holder directory. Hold on to it. |
926 | */ |
927 | kobject_get(bdev->bd_part->holder_dir); |
928 | |
929 | list_add(&holder->list, &bdev->bd_holder_disks); |
930 | goto out_unlock; |
931 | |
932 | out_del: |
933 | del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
934 | out_free: |
935 | kfree(holder); |
936 | out_unlock: |
937 | mutex_unlock(&bdev->bd_mutex); |
938 | return ret; |
939 | } |
940 | EXPORT_SYMBOL_GPL(bd_link_disk_holder); |
941 | |
942 | /** |
943 | * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder() |
944 | * @bdev: the calimed slave bdev |
945 | * @disk: the holding disk |
946 | * |
947 | * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. |
948 | * |
949 | * CONTEXT: |
950 | * Might sleep. |
951 | */ |
952 | void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) |
953 | { |
954 | struct bd_holder_disk *holder; |
955 | |
956 | mutex_lock(&bdev->bd_mutex); |
957 | |
958 | holder = bd_find_holder_disk(bdev, disk); |
959 | |
960 | if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) { |
961 | del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); |
962 | del_symlink(bdev->bd_part->holder_dir, |
963 | &disk_to_dev(disk)->kobj); |
964 | kobject_put(bdev->bd_part->holder_dir); |
965 | list_del_init(&holder->list); |
966 | kfree(holder); |
967 | } |
968 | |
969 | mutex_unlock(&bdev->bd_mutex); |
970 | } |
971 | EXPORT_SYMBOL_GPL(bd_unlink_disk_holder); |
972 | #endif |
973 | |
974 | /** |
975 | * flush_disk - invalidates all buffer-cache entries on a disk |
976 | * |
977 | * @bdev: struct block device to be flushed |
978 | * @kill_dirty: flag to guide handling of dirty inodes |
979 | * |
980 | * Invalidates all buffer-cache entries on a disk. It should be called |
981 | * when a disk has been changed -- either by a media change or online |
982 | * resize. |
983 | */ |
984 | static void flush_disk(struct block_device *bdev, bool kill_dirty) |
985 | { |
986 | if (__invalidate_device(bdev, kill_dirty)) { |
987 | char name[BDEVNAME_SIZE] = ""; |
988 | |
989 | if (bdev->bd_disk) |
990 | disk_name(bdev->bd_disk, 0, name); |
991 | printk(KERN_WARNING "VFS: busy inodes on changed media or " |
992 | "resized disk %s\n", name); |
993 | } |
994 | |
995 | if (!bdev->bd_disk) |
996 | return; |
997 | if (disk_part_scan_enabled(bdev->bd_disk)) |
998 | bdev->bd_invalidated = 1; |
999 | } |
1000 | |
1001 | /** |
1002 | * check_disk_size_change - checks for disk size change and adjusts bdev size. |
1003 | * @disk: struct gendisk to check |
1004 | * @bdev: struct bdev to adjust. |
1005 | * |
1006 | * This routine checks to see if the bdev size does not match the disk size |
1007 | * and adjusts it if it differs. |
1008 | */ |
1009 | void check_disk_size_change(struct gendisk *disk, struct block_device *bdev) |
1010 | { |
1011 | loff_t disk_size, bdev_size; |
1012 | |
1013 | disk_size = (loff_t)get_capacity(disk) << 9; |
1014 | bdev_size = i_size_read(bdev->bd_inode); |
1015 | if (disk_size != bdev_size) { |
1016 | char name[BDEVNAME_SIZE]; |
1017 | |
1018 | disk_name(disk, 0, name); |
1019 | printk(KERN_INFO |
1020 | "%s: detected capacity change from %lld to %lld\n", |
1021 | name, bdev_size, disk_size); |
1022 | i_size_write(bdev->bd_inode, disk_size); |
1023 | flush_disk(bdev, false); |
1024 | } |
1025 | } |
1026 | EXPORT_SYMBOL(check_disk_size_change); |
1027 | |
1028 | /** |
1029 | * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back |
1030 | * @disk: struct gendisk to be revalidated |
1031 | * |
1032 | * This routine is a wrapper for lower-level driver's revalidate_disk |
1033 | * call-backs. It is used to do common pre and post operations needed |
1034 | * for all revalidate_disk operations. |
1035 | */ |
1036 | int revalidate_disk(struct gendisk *disk) |
1037 | { |
1038 | struct block_device *bdev; |
1039 | int ret = 0; |
1040 | |
1041 | if (disk->fops->revalidate_disk) |
1042 | ret = disk->fops->revalidate_disk(disk); |
1043 | |
1044 | bdev = bdget_disk(disk, 0); |
1045 | if (!bdev) |
1046 | return ret; |
1047 | |
1048 | mutex_lock(&bdev->bd_mutex); |
1049 | check_disk_size_change(disk, bdev); |
1050 | mutex_unlock(&bdev->bd_mutex); |
1051 | bdput(bdev); |
1052 | return ret; |
1053 | } |
1054 | EXPORT_SYMBOL(revalidate_disk); |
1055 | |
1056 | /* |
1057 | * This routine checks whether a removable media has been changed, |
1058 | * and invalidates all buffer-cache-entries in that case. This |
1059 | * is a relatively slow routine, so we have to try to minimize using |
1060 | * it. Thus it is called only upon a 'mount' or 'open'. This |
1061 | * is the best way of combining speed and utility, I think. |
1062 | * People changing diskettes in the middle of an operation deserve |
1063 | * to lose :-) |
1064 | */ |
1065 | int check_disk_change(struct block_device *bdev) |
1066 | { |
1067 | struct gendisk *disk = bdev->bd_disk; |
1068 | const struct block_device_operations *bdops = disk->fops; |
1069 | unsigned int events; |
1070 | |
1071 | events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE | |
1072 | DISK_EVENT_EJECT_REQUEST); |
1073 | if (!(events & DISK_EVENT_MEDIA_CHANGE)) |
1074 | return 0; |
1075 | |
1076 | flush_disk(bdev, true); |
1077 | if (bdops->revalidate_disk) |
1078 | bdops->revalidate_disk(bdev->bd_disk); |
1079 | return 1; |
1080 | } |
1081 | |
1082 | EXPORT_SYMBOL(check_disk_change); |
1083 | |
1084 | void bd_set_size(struct block_device *bdev, loff_t size) |
1085 | { |
1086 | unsigned bsize = bdev_logical_block_size(bdev); |
1087 | |
1088 | bdev->bd_inode->i_size = size; |
1089 | while (bsize < PAGE_CACHE_SIZE) { |
1090 | if (size & bsize) |
1091 | break; |
1092 | bsize <<= 1; |
1093 | } |
1094 | bdev->bd_block_size = bsize; |
1095 | bdev->bd_inode->i_blkbits = blksize_bits(bsize); |
1096 | } |
1097 | EXPORT_SYMBOL(bd_set_size); |
1098 | |
1099 | static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part); |
1100 | |
1101 | /* |
1102 | * bd_mutex locking: |
1103 | * |
1104 | * mutex_lock(part->bd_mutex) |
1105 | * mutex_lock_nested(whole->bd_mutex, 1) |
1106 | */ |
1107 | |
1108 | static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) |
1109 | { |
1110 | struct gendisk *disk; |
1111 | struct module *owner; |
1112 | int ret; |
1113 | int partno; |
1114 | int perm = 0; |
1115 | |
1116 | if (mode & FMODE_READ) |
1117 | perm |= MAY_READ; |
1118 | if (mode & FMODE_WRITE) |
1119 | perm |= MAY_WRITE; |
1120 | /* |
1121 | * hooks: /n/, see "layering violations". |
1122 | */ |
1123 | if (!for_part) { |
1124 | ret = devcgroup_inode_permission(bdev->bd_inode, perm); |
1125 | if (ret != 0) { |
1126 | bdput(bdev); |
1127 | return ret; |
1128 | } |
1129 | } |
1130 | |
1131 | restart: |
1132 | |
1133 | ret = -ENXIO; |
1134 | disk = get_gendisk(bdev->bd_dev, &partno); |
1135 | if (!disk) |
1136 | goto out; |
1137 | owner = disk->fops->owner; |
1138 | |
1139 | disk_block_events(disk); |
1140 | mutex_lock_nested(&bdev->bd_mutex, for_part); |
1141 | if (!bdev->bd_openers) { |
1142 | bdev->bd_disk = disk; |
1143 | bdev->bd_queue = disk->queue; |
1144 | bdev->bd_contains = bdev; |
1145 | if (!partno) { |
1146 | struct backing_dev_info *bdi; |
1147 | |
1148 | ret = -ENXIO; |
1149 | bdev->bd_part = disk_get_part(disk, partno); |
1150 | if (!bdev->bd_part) |
1151 | goto out_clear; |
1152 | |
1153 | ret = 0; |
1154 | if (disk->fops->open) { |
1155 | ret = disk->fops->open(bdev, mode); |
1156 | if (ret == -ERESTARTSYS) { |
1157 | /* Lost a race with 'disk' being |
1158 | * deleted, try again. |
1159 | * See md.c |
1160 | */ |
1161 | disk_put_part(bdev->bd_part); |
1162 | bdev->bd_part = NULL; |
1163 | bdev->bd_disk = NULL; |
1164 | bdev->bd_queue = NULL; |
1165 | mutex_unlock(&bdev->bd_mutex); |
1166 | disk_unblock_events(disk); |
1167 | put_disk(disk); |
1168 | module_put(owner); |
1169 | goto restart; |
1170 | } |
1171 | } |
1172 | |
1173 | if (!ret && !bdev->bd_openers) { |
1174 | bd_set_size(bdev,(loff_t)get_capacity(disk)<<9); |
1175 | bdi = blk_get_backing_dev_info(bdev); |
1176 | if (bdi == NULL) |
1177 | bdi = &default_backing_dev_info; |
1178 | bdev_inode_switch_bdi(bdev->bd_inode, bdi); |
1179 | } |
1180 | |
1181 | /* |
1182 | * If the device is invalidated, rescan partition |
1183 | * if open succeeded or failed with -ENOMEDIUM. |
1184 | * The latter is necessary to prevent ghost |
1185 | * partitions on a removed medium. |
1186 | */ |
1187 | if (bdev->bd_invalidated) { |
1188 | if (!ret) |
1189 | rescan_partitions(disk, bdev); |
1190 | else if (ret == -ENOMEDIUM) |
1191 | invalidate_partitions(disk, bdev); |
1192 | } |
1193 | if (ret) |
1194 | goto out_clear; |
1195 | } else { |
1196 | struct block_device *whole; |
1197 | whole = bdget_disk(disk, 0); |
1198 | ret = -ENOMEM; |
1199 | if (!whole) |
1200 | goto out_clear; |
1201 | BUG_ON(for_part); |
1202 | ret = __blkdev_get(whole, mode, 1); |
1203 | if (ret) |
1204 | goto out_clear; |
1205 | bdev->bd_contains = whole; |
1206 | bdev_inode_switch_bdi(bdev->bd_inode, |
1207 | whole->bd_inode->i_data.backing_dev_info); |
1208 | bdev->bd_part = disk_get_part(disk, partno); |
1209 | if (!(disk->flags & GENHD_FL_UP) || |
1210 | !bdev->bd_part || !bdev->bd_part->nr_sects) { |
1211 | ret = -ENXIO; |
1212 | goto out_clear; |
1213 | } |
1214 | bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9); |
1215 | } |
1216 | } else { |
1217 | if (bdev->bd_contains == bdev) { |
1218 | ret = 0; |
1219 | if (bdev->bd_disk->fops->open) |
1220 | ret = bdev->bd_disk->fops->open(bdev, mode); |
1221 | /* the same as first opener case, read comment there */ |
1222 | if (bdev->bd_invalidated) { |
1223 | if (!ret) |
1224 | rescan_partitions(bdev->bd_disk, bdev); |
1225 | else if (ret == -ENOMEDIUM) |
1226 | invalidate_partitions(bdev->bd_disk, bdev); |
1227 | } |
1228 | if (ret) |
1229 | goto out_unlock_bdev; |
1230 | } |
1231 | /* only one opener holds refs to the module and disk */ |
1232 | put_disk(disk); |
1233 | module_put(owner); |
1234 | } |
1235 | bdev->bd_openers++; |
1236 | if (for_part) |
1237 | bdev->bd_part_count++; |
1238 | mutex_unlock(&bdev->bd_mutex); |
1239 | disk_unblock_events(disk); |
1240 | return 0; |
1241 | |
1242 | out_clear: |
1243 | disk_put_part(bdev->bd_part); |
1244 | bdev->bd_disk = NULL; |
1245 | bdev->bd_part = NULL; |
1246 | bdev->bd_queue = NULL; |
1247 | bdev_inode_switch_bdi(bdev->bd_inode, &default_backing_dev_info); |
1248 | if (bdev != bdev->bd_contains) |
1249 | __blkdev_put(bdev->bd_contains, mode, 1); |
1250 | bdev->bd_contains = NULL; |
1251 | out_unlock_bdev: |
1252 | mutex_unlock(&bdev->bd_mutex); |
1253 | disk_unblock_events(disk); |
1254 | put_disk(disk); |
1255 | module_put(owner); |
1256 | out: |
1257 | bdput(bdev); |
1258 | |
1259 | return ret; |
1260 | } |
1261 | |
1262 | /** |
1263 | * blkdev_get - open a block device |
1264 | * @bdev: block_device to open |
1265 | * @mode: FMODE_* mask |
1266 | * @holder: exclusive holder identifier |
1267 | * |
1268 | * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is |
1269 | * open with exclusive access. Specifying %FMODE_EXCL with %NULL |
1270 | * @holder is invalid. Exclusive opens may nest for the same @holder. |
1271 | * |
1272 | * On success, the reference count of @bdev is unchanged. On failure, |
1273 | * @bdev is put. |
1274 | * |
1275 | * CONTEXT: |
1276 | * Might sleep. |
1277 | * |
1278 | * RETURNS: |
1279 | * 0 on success, -errno on failure. |
1280 | */ |
1281 | int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) |
1282 | { |
1283 | struct block_device *whole = NULL; |
1284 | int res; |
1285 | |
1286 | WARN_ON_ONCE((mode & FMODE_EXCL) && !holder); |
1287 | |
1288 | if ((mode & FMODE_EXCL) && holder) { |
1289 | whole = bd_start_claiming(bdev, holder); |
1290 | if (IS_ERR(whole)) { |
1291 | bdput(bdev); |
1292 | return PTR_ERR(whole); |
1293 | } |
1294 | } |
1295 | |
1296 | res = __blkdev_get(bdev, mode, 0); |
1297 | |
1298 | if (whole) { |
1299 | struct gendisk *disk = whole->bd_disk; |
1300 | |
1301 | /* finish claiming */ |
1302 | mutex_lock(&bdev->bd_mutex); |
1303 | spin_lock(&bdev_lock); |
1304 | |
1305 | if (!res) { |
1306 | BUG_ON(!bd_may_claim(bdev, whole, holder)); |
1307 | /* |
1308 | * Note that for a whole device bd_holders |
1309 | * will be incremented twice, and bd_holder |
1310 | * will be set to bd_may_claim before being |
1311 | * set to holder |
1312 | */ |
1313 | whole->bd_holders++; |
1314 | whole->bd_holder = bd_may_claim; |
1315 | bdev->bd_holders++; |
1316 | bdev->bd_holder = holder; |
1317 | } |
1318 | |
1319 | /* tell others that we're done */ |
1320 | BUG_ON(whole->bd_claiming != holder); |
1321 | whole->bd_claiming = NULL; |
1322 | wake_up_bit(&whole->bd_claiming, 0); |
1323 | |
1324 | spin_unlock(&bdev_lock); |
1325 | |
1326 | /* |
1327 | * Block event polling for write claims if requested. Any |
1328 | * write holder makes the write_holder state stick until |
1329 | * all are released. This is good enough and tracking |
1330 | * individual writeable reference is too fragile given the |
1331 | * way @mode is used in blkdev_get/put(). |
1332 | */ |
1333 | if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder && |
1334 | (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { |
1335 | bdev->bd_write_holder = true; |
1336 | disk_block_events(disk); |
1337 | } |
1338 | |
1339 | mutex_unlock(&bdev->bd_mutex); |
1340 | bdput(whole); |
1341 | } |
1342 | |
1343 | return res; |
1344 | } |
1345 | EXPORT_SYMBOL(blkdev_get); |
1346 | |
1347 | /** |
1348 | * blkdev_get_by_path - open a block device by name |
1349 | * @path: path to the block device to open |
1350 | * @mode: FMODE_* mask |
1351 | * @holder: exclusive holder identifier |
1352 | * |
1353 | * Open the blockdevice described by the device file at @path. @mode |
1354 | * and @holder are identical to blkdev_get(). |
1355 | * |
1356 | * On success, the returned block_device has reference count of one. |
1357 | * |
1358 | * CONTEXT: |
1359 | * Might sleep. |
1360 | * |
1361 | * RETURNS: |
1362 | * Pointer to block_device on success, ERR_PTR(-errno) on failure. |
1363 | */ |
1364 | struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, |
1365 | void *holder) |
1366 | { |
1367 | struct block_device *bdev; |
1368 | int err; |
1369 | |
1370 | bdev = lookup_bdev(path); |
1371 | if (IS_ERR(bdev)) |
1372 | return bdev; |
1373 | |
1374 | err = blkdev_get(bdev, mode, holder); |
1375 | if (err) |
1376 | return ERR_PTR(err); |
1377 | |
1378 | if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) { |
1379 | blkdev_put(bdev, mode); |
1380 | return ERR_PTR(-EACCES); |
1381 | } |
1382 | |
1383 | return bdev; |
1384 | } |
1385 | EXPORT_SYMBOL(blkdev_get_by_path); |
1386 | |
1387 | /** |
1388 | * blkdev_get_by_dev - open a block device by device number |
1389 | * @dev: device number of block device to open |
1390 | * @mode: FMODE_* mask |
1391 | * @holder: exclusive holder identifier |
1392 | * |
1393 | * Open the blockdevice described by device number @dev. @mode and |
1394 | * @holder are identical to blkdev_get(). |
1395 | * |
1396 | * Use it ONLY if you really do not have anything better - i.e. when |
1397 | * you are behind a truly sucky interface and all you are given is a |
1398 | * device number. _Never_ to be used for internal purposes. If you |
1399 | * ever need it - reconsider your API. |
1400 | * |
1401 | * On success, the returned block_device has reference count of one. |
1402 | * |
1403 | * CONTEXT: |
1404 | * Might sleep. |
1405 | * |
1406 | * RETURNS: |
1407 | * Pointer to block_device on success, ERR_PTR(-errno) on failure. |
1408 | */ |
1409 | struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) |
1410 | { |
1411 | struct block_device *bdev; |
1412 | int err; |
1413 | |
1414 | bdev = bdget(dev); |
1415 | if (!bdev) |
1416 | return ERR_PTR(-ENOMEM); |
1417 | |
1418 | err = blkdev_get(bdev, mode, holder); |
1419 | if (err) |
1420 | return ERR_PTR(err); |
1421 | |
1422 | return bdev; |
1423 | } |
1424 | EXPORT_SYMBOL(blkdev_get_by_dev); |
1425 | |
1426 | static int blkdev_open(struct inode * inode, struct file * filp) |
1427 | { |
1428 | struct block_device *bdev; |
1429 | |
1430 | /* |
1431 | * Preserve backwards compatibility and allow large file access |
1432 | * even if userspace doesn't ask for it explicitly. Some mkfs |
1433 | * binary needs it. We might want to drop this workaround |
1434 | * during an unstable branch. |
1435 | */ |
1436 | filp->f_flags |= O_LARGEFILE; |
1437 | |
1438 | if (filp->f_flags & O_NDELAY) |
1439 | filp->f_mode |= FMODE_NDELAY; |
1440 | if (filp->f_flags & O_EXCL) |
1441 | filp->f_mode |= FMODE_EXCL; |
1442 | if ((filp->f_flags & O_ACCMODE) == 3) |
1443 | filp->f_mode |= FMODE_WRITE_IOCTL; |
1444 | |
1445 | bdev = bd_acquire(inode); |
1446 | if (bdev == NULL) |
1447 | return -ENOMEM; |
1448 | |
1449 | filp->f_mapping = bdev->bd_inode->i_mapping; |
1450 | |
1451 | return blkdev_get(bdev, filp->f_mode, filp); |
1452 | } |
1453 | |
1454 | static int __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) |
1455 | { |
1456 | int ret = 0; |
1457 | struct gendisk *disk = bdev->bd_disk; |
1458 | struct block_device *victim = NULL; |
1459 | |
1460 | mutex_lock_nested(&bdev->bd_mutex, for_part); |
1461 | if (for_part) |
1462 | bdev->bd_part_count--; |
1463 | |
1464 | if (!--bdev->bd_openers) { |
1465 | WARN_ON_ONCE(bdev->bd_holders); |
1466 | sync_blockdev(bdev); |
1467 | kill_bdev(bdev); |
1468 | /* ->release can cause the old bdi to disappear, |
1469 | * so must switch it out first |
1470 | */ |
1471 | bdev_inode_switch_bdi(bdev->bd_inode, |
1472 | &default_backing_dev_info); |
1473 | } |
1474 | if (bdev->bd_contains == bdev) { |
1475 | if (disk->fops->release) |
1476 | ret = disk->fops->release(disk, mode); |
1477 | } |
1478 | if (!bdev->bd_openers) { |
1479 | struct module *owner = disk->fops->owner; |
1480 | |
1481 | disk_put_part(bdev->bd_part); |
1482 | bdev->bd_part = NULL; |
1483 | bdev->bd_disk = NULL; |
1484 | if (bdev != bdev->bd_contains) |
1485 | victim = bdev->bd_contains; |
1486 | bdev->bd_contains = NULL; |
1487 | |
1488 | put_disk(disk); |
1489 | module_put(owner); |
1490 | } |
1491 | mutex_unlock(&bdev->bd_mutex); |
1492 | bdput(bdev); |
1493 | if (victim) |
1494 | __blkdev_put(victim, mode, 1); |
1495 | return ret; |
1496 | } |
1497 | |
1498 | int blkdev_put(struct block_device *bdev, fmode_t mode) |
1499 | { |
1500 | mutex_lock(&bdev->bd_mutex); |
1501 | |
1502 | if (mode & FMODE_EXCL) { |
1503 | bool bdev_free; |
1504 | |
1505 | /* |
1506 | * Release a claim on the device. The holder fields |
1507 | * are protected with bdev_lock. bd_mutex is to |
1508 | * synchronize disk_holder unlinking. |
1509 | */ |
1510 | spin_lock(&bdev_lock); |
1511 | |
1512 | WARN_ON_ONCE(--bdev->bd_holders < 0); |
1513 | WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0); |
1514 | |
1515 | /* bd_contains might point to self, check in a separate step */ |
1516 | if ((bdev_free = !bdev->bd_holders)) |
1517 | bdev->bd_holder = NULL; |
1518 | if (!bdev->bd_contains->bd_holders) |
1519 | bdev->bd_contains->bd_holder = NULL; |
1520 | |
1521 | spin_unlock(&bdev_lock); |
1522 | |
1523 | /* |
1524 | * If this was the last claim, remove holder link and |
1525 | * unblock evpoll if it was a write holder. |
1526 | */ |
1527 | if (bdev_free && bdev->bd_write_holder) { |
1528 | disk_unblock_events(bdev->bd_disk); |
1529 | bdev->bd_write_holder = false; |
1530 | } |
1531 | } |
1532 | |
1533 | /* |
1534 | * Trigger event checking and tell drivers to flush MEDIA_CHANGE |
1535 | * event. This is to ensure detection of media removal commanded |
1536 | * from userland - e.g. eject(1). |
1537 | */ |
1538 | disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE); |
1539 | |
1540 | mutex_unlock(&bdev->bd_mutex); |
1541 | |
1542 | return __blkdev_put(bdev, mode, 0); |
1543 | } |
1544 | EXPORT_SYMBOL(blkdev_put); |
1545 | |
1546 | static int blkdev_close(struct inode * inode, struct file * filp) |
1547 | { |
1548 | struct block_device *bdev = I_BDEV(filp->f_mapping->host); |
1549 | |
1550 | return blkdev_put(bdev, filp->f_mode); |
1551 | } |
1552 | |
1553 | static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg) |
1554 | { |
1555 | struct block_device *bdev = I_BDEV(file->f_mapping->host); |
1556 | fmode_t mode = file->f_mode; |
1557 | |
1558 | /* |
1559 | * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have |
1560 | * to updated it before every ioctl. |
1561 | */ |
1562 | if (file->f_flags & O_NDELAY) |
1563 | mode |= FMODE_NDELAY; |
1564 | else |
1565 | mode &= ~FMODE_NDELAY; |
1566 | |
1567 | return blkdev_ioctl(bdev, mode, cmd, arg); |
1568 | } |
1569 | |
1570 | /* |
1571 | * Write data to the block device. Only intended for the block device itself |
1572 | * and the raw driver which basically is a fake block device. |
1573 | * |
1574 | * Does not take i_mutex for the write and thus is not for general purpose |
1575 | * use. |
1576 | */ |
1577 | ssize_t blkdev_aio_write(struct kiocb *iocb, const struct iovec *iov, |
1578 | unsigned long nr_segs, loff_t pos) |
1579 | { |
1580 | struct file *file = iocb->ki_filp; |
1581 | struct blk_plug plug; |
1582 | ssize_t ret; |
1583 | |
1584 | BUG_ON(iocb->ki_pos != pos); |
1585 | |
1586 | blk_start_plug(&plug); |
1587 | ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos); |
1588 | if (ret > 0 || ret == -EIOCBQUEUED) { |
1589 | ssize_t err; |
1590 | |
1591 | err = generic_write_sync(file, pos, ret); |
1592 | if (err < 0 && ret > 0) |
1593 | ret = err; |
1594 | } |
1595 | blk_finish_plug(&plug); |
1596 | return ret; |
1597 | } |
1598 | EXPORT_SYMBOL_GPL(blkdev_aio_write); |
1599 | |
1600 | /* |
1601 | * Try to release a page associated with block device when the system |
1602 | * is under memory pressure. |
1603 | */ |
1604 | static int blkdev_releasepage(struct page *page, gfp_t wait) |
1605 | { |
1606 | struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super; |
1607 | |
1608 | if (super && super->s_op->bdev_try_to_free_page) |
1609 | return super->s_op->bdev_try_to_free_page(super, page, wait); |
1610 | |
1611 | return try_to_free_buffers(page); |
1612 | } |
1613 | |
1614 | static const struct address_space_operations def_blk_aops = { |
1615 | .readpage = blkdev_readpage, |
1616 | .writepage = blkdev_writepage, |
1617 | .write_begin = blkdev_write_begin, |
1618 | .write_end = blkdev_write_end, |
1619 | .writepages = generic_writepages, |
1620 | .releasepage = blkdev_releasepage, |
1621 | .direct_IO = blkdev_direct_IO, |
1622 | }; |
1623 | |
1624 | const struct file_operations def_blk_fops = { |
1625 | .open = blkdev_open, |
1626 | .release = blkdev_close, |
1627 | .llseek = block_llseek, |
1628 | .read = do_sync_read, |
1629 | .write = do_sync_write, |
1630 | .aio_read = generic_file_aio_read, |
1631 | .aio_write = blkdev_aio_write, |
1632 | .mmap = generic_file_mmap, |
1633 | .fsync = blkdev_fsync, |
1634 | .unlocked_ioctl = block_ioctl, |
1635 | #ifdef CONFIG_COMPAT |
1636 | .compat_ioctl = compat_blkdev_ioctl, |
1637 | #endif |
1638 | .splice_read = generic_file_splice_read, |
1639 | .splice_write = generic_file_splice_write, |
1640 | }; |
1641 | |
1642 | int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg) |
1643 | { |
1644 | int res; |
1645 | mm_segment_t old_fs = get_fs(); |
1646 | set_fs(KERNEL_DS); |
1647 | res = blkdev_ioctl(bdev, 0, cmd, arg); |
1648 | set_fs(old_fs); |
1649 | return res; |
1650 | } |
1651 | |
1652 | EXPORT_SYMBOL(ioctl_by_bdev); |
1653 | |
1654 | /** |
1655 | * lookup_bdev - lookup a struct block_device by name |
1656 | * @pathname: special file representing the block device |
1657 | * |
1658 | * Get a reference to the blockdevice at @pathname in the current |
1659 | * namespace if possible and return it. Return ERR_PTR(error) |
1660 | * otherwise. |
1661 | */ |
1662 | struct block_device *lookup_bdev(const char *pathname) |
1663 | { |
1664 | struct block_device *bdev; |
1665 | struct inode *inode; |
1666 | struct path path; |
1667 | int error; |
1668 | |
1669 | if (!pathname || !*pathname) |
1670 | return ERR_PTR(-EINVAL); |
1671 | |
1672 | error = kern_path(pathname, LOOKUP_FOLLOW, &path); |
1673 | if (error) |
1674 | return ERR_PTR(error); |
1675 | |
1676 | inode = path.dentry->d_inode; |
1677 | error = -ENOTBLK; |
1678 | if (!S_ISBLK(inode->i_mode)) |
1679 | goto fail; |
1680 | error = -EACCES; |
1681 | if (path.mnt->mnt_flags & MNT_NODEV) |
1682 | goto fail; |
1683 | error = -ENOMEM; |
1684 | bdev = bd_acquire(inode); |
1685 | if (!bdev) |
1686 | goto fail; |
1687 | out: |
1688 | path_put(&path); |
1689 | return bdev; |
1690 | fail: |
1691 | bdev = ERR_PTR(error); |
1692 | goto out; |
1693 | } |
1694 | EXPORT_SYMBOL(lookup_bdev); |
1695 | |
1696 | int __invalidate_device(struct block_device *bdev, bool kill_dirty) |
1697 | { |
1698 | struct super_block *sb = get_super(bdev); |
1699 | int res = 0; |
1700 | |
1701 | if (sb) { |
1702 | /* |
1703 | * no need to lock the super, get_super holds the |
1704 | * read mutex so the filesystem cannot go away |
1705 | * under us (->put_super runs with the write lock |
1706 | * hold). |
1707 | */ |
1708 | shrink_dcache_sb(sb); |
1709 | res = invalidate_inodes(sb, kill_dirty); |
1710 | drop_super(sb); |
1711 | } |
1712 | invalidate_bdev(bdev); |
1713 | return res; |
1714 | } |
1715 | EXPORT_SYMBOL(__invalidate_device); |
1716 | |
1717 | void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg) |
1718 | { |
1719 | struct inode *inode, *old_inode = NULL; |
1720 | |
1721 | spin_lock(&inode_sb_list_lock); |
1722 | list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) { |
1723 | struct address_space *mapping = inode->i_mapping; |
1724 | |
1725 | spin_lock(&inode->i_lock); |
1726 | if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) || |
1727 | mapping->nrpages == 0) { |
1728 | spin_unlock(&inode->i_lock); |
1729 | continue; |
1730 | } |
1731 | __iget(inode); |
1732 | spin_unlock(&inode->i_lock); |
1733 | spin_unlock(&inode_sb_list_lock); |
1734 | /* |
1735 | * We hold a reference to 'inode' so it couldn't have been |
1736 | * removed from s_inodes list while we dropped the |
1737 | * inode_sb_list_lock. We cannot iput the inode now as we can |
1738 | * be holding the last reference and we cannot iput it under |
1739 | * inode_sb_list_lock. So we keep the reference and iput it |
1740 | * later. |
1741 | */ |
1742 | iput(old_inode); |
1743 | old_inode = inode; |
1744 | |
1745 | func(I_BDEV(inode), arg); |
1746 | |
1747 | spin_lock(&inode_sb_list_lock); |
1748 | } |
1749 | spin_unlock(&inode_sb_list_lock); |
1750 | iput(old_inode); |
1751 | } |
1752 |
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v2.6.34-rc5
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