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