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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/backing-dev.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/blkpg.h> | |
20 | #include <linux/magic.h> | |
21 | #include <linux/dax.h> | |
22 | #include <linux/buffer_head.h> | |
23 | #include <linux/swap.h> | |
24 | #include <linux/pagevec.h> | |
25 | #include <linux/writeback.h> | |
26 | #include <linux/mpage.h> | |
27 | #include <linux/mount.h> | |
28 | #include <linux/uio.h> | |
29 | #include <linux/namei.h> | |
30 | #include <linux/log2.h> | |
31 | #include <linux/cleancache.h> | |
32 | #include <linux/dax.h> | |
33 | #include <linux/badblocks.h> | |
34 | #include <linux/task_io_accounting_ops.h> | |
35 | #include <linux/falloc.h> | |
36 | #include <linux/uaccess.h> | |
37 | #include "internal.h" | |
38 | ||
39 | struct bdev_inode { | |
40 | struct block_device bdev; | |
41 | struct inode vfs_inode; | |
42 | }; | |
43 | ||
44 | static const struct address_space_operations def_blk_aops; | |
45 | ||
46 | static inline struct bdev_inode *BDEV_I(struct inode *inode) | |
47 | { | |
48 | return container_of(inode, struct bdev_inode, vfs_inode); | |
49 | } | |
50 | ||
51 | struct block_device *I_BDEV(struct inode *inode) | |
52 | { | |
53 | return &BDEV_I(inode)->bdev; | |
54 | } | |
55 | EXPORT_SYMBOL(I_BDEV); | |
56 | ||
57 | static void bdev_write_inode(struct block_device *bdev) | |
58 | { | |
59 | struct inode *inode = bdev->bd_inode; | |
60 | int ret; | |
61 | ||
62 | spin_lock(&inode->i_lock); | |
63 | while (inode->i_state & I_DIRTY) { | |
64 | spin_unlock(&inode->i_lock); | |
65 | ret = write_inode_now(inode, true); | |
66 | if (ret) { | |
67 | char name[BDEVNAME_SIZE]; | |
68 | pr_warn_ratelimited("VFS: Dirty inode writeback failed " | |
69 | "for block device %s (err=%d).\n", | |
70 | bdevname(bdev, name), ret); | |
71 | } | |
72 | spin_lock(&inode->i_lock); | |
73 | } | |
74 | spin_unlock(&inode->i_lock); | |
75 | } | |
76 | ||
77 | /* Kill _all_ buffers and pagecache , dirty or not.. */ | |
78 | void kill_bdev(struct block_device *bdev) | |
79 | { | |
80 | struct address_space *mapping = bdev->bd_inode->i_mapping; | |
81 | ||
82 | if (mapping->nrpages == 0 && mapping->nrexceptional == 0) | |
83 | return; | |
84 | ||
85 | invalidate_bh_lrus(); | |
86 | truncate_inode_pages(mapping, 0); | |
87 | } | |
88 | EXPORT_SYMBOL(kill_bdev); | |
89 | ||
90 | /* Invalidate clean unused buffers and pagecache. */ | |
91 | void invalidate_bdev(struct block_device *bdev) | |
92 | { | |
93 | struct address_space *mapping = bdev->bd_inode->i_mapping; | |
94 | ||
95 | if (mapping->nrpages) { | |
96 | invalidate_bh_lrus(); | |
97 | lru_add_drain_all(); /* make sure all lru add caches are flushed */ | |
98 | invalidate_mapping_pages(mapping, 0, -1); | |
99 | } | |
100 | /* 99% of the time, we don't need to flush the cleancache on the bdev. | |
101 | * But, for the strange corners, lets be cautious | |
102 | */ | |
103 | cleancache_invalidate_inode(mapping); | |
104 | } | |
105 | EXPORT_SYMBOL(invalidate_bdev); | |
106 | ||
107 | int set_blocksize(struct block_device *bdev, int size) | |
108 | { | |
109 | /* Size must be a power of two, and between 512 and PAGE_SIZE */ | |
110 | if (size > PAGE_SIZE || size < 512 || !is_power_of_2(size)) | |
111 | return -EINVAL; | |
112 | ||
113 | /* Size cannot be smaller than the size supported by the device */ | |
114 | if (size < bdev_logical_block_size(bdev)) | |
115 | return -EINVAL; | |
116 | ||
117 | /* Don't change the size if it is same as current */ | |
118 | if (bdev->bd_block_size != size) { | |
119 | sync_blockdev(bdev); | |
120 | bdev->bd_block_size = size; | |
121 | bdev->bd_inode->i_blkbits = blksize_bits(size); | |
122 | kill_bdev(bdev); | |
123 | } | |
124 | return 0; | |
125 | } | |
126 | ||
127 | EXPORT_SYMBOL(set_blocksize); | |
128 | ||
129 | int sb_set_blocksize(struct super_block *sb, int size) | |
130 | { | |
131 | if (set_blocksize(sb->s_bdev, size)) | |
132 | return 0; | |
133 | /* If we get here, we know size is power of two | |
134 | * and it's value is between 512 and PAGE_SIZE */ | |
135 | sb->s_blocksize = size; | |
136 | sb->s_blocksize_bits = blksize_bits(size); | |
137 | return sb->s_blocksize; | |
138 | } | |
139 | ||
140 | EXPORT_SYMBOL(sb_set_blocksize); | |
141 | ||
142 | int sb_min_blocksize(struct super_block *sb, int size) | |
143 | { | |
144 | int minsize = bdev_logical_block_size(sb->s_bdev); | |
145 | if (size < minsize) | |
146 | size = minsize; | |
147 | return sb_set_blocksize(sb, size); | |
148 | } | |
149 | ||
150 | EXPORT_SYMBOL(sb_min_blocksize); | |
151 | ||
152 | static int | |
153 | blkdev_get_block(struct inode *inode, sector_t iblock, | |
154 | struct buffer_head *bh, int create) | |
155 | { | |
156 | bh->b_bdev = I_BDEV(inode); | |
157 | bh->b_blocknr = iblock; | |
158 | set_buffer_mapped(bh); | |
159 | return 0; | |
160 | } | |
161 | ||
162 | static struct inode *bdev_file_inode(struct file *file) | |
163 | { | |
164 | return file->f_mapping->host; | |
165 | } | |
166 | ||
167 | static unsigned int dio_bio_write_op(struct kiocb *iocb) | |
168 | { | |
169 | unsigned int op = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE; | |
170 | ||
171 | /* avoid the need for a I/O completion work item */ | |
172 | if (iocb->ki_flags & IOCB_DSYNC) | |
173 | op |= REQ_FUA; | |
174 | return op; | |
175 | } | |
176 | ||
177 | #define DIO_INLINE_BIO_VECS 4 | |
178 | ||
179 | static void blkdev_bio_end_io_simple(struct bio *bio) | |
180 | { | |
181 | struct task_struct *waiter = bio->bi_private; | |
182 | ||
183 | WRITE_ONCE(bio->bi_private, NULL); | |
184 | wake_up_process(waiter); | |
185 | } | |
186 | ||
187 | static ssize_t | |
188 | __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter, | |
189 | int nr_pages) | |
190 | { | |
191 | struct file *file = iocb->ki_filp; | |
192 | struct block_device *bdev = I_BDEV(bdev_file_inode(file)); | |
193 | struct bio_vec inline_vecs[DIO_INLINE_BIO_VECS], *vecs, *bvec; | |
194 | loff_t pos = iocb->ki_pos; | |
195 | bool should_dirty = false; | |
196 | struct bio bio; | |
197 | ssize_t ret; | |
198 | blk_qc_t qc; | |
199 | int i; | |
200 | ||
201 | if ((pos | iov_iter_alignment(iter)) & | |
202 | (bdev_logical_block_size(bdev) - 1)) | |
203 | return -EINVAL; | |
204 | ||
205 | if (nr_pages <= DIO_INLINE_BIO_VECS) | |
206 | vecs = inline_vecs; | |
207 | else { | |
208 | vecs = kmalloc(nr_pages * sizeof(struct bio_vec), GFP_KERNEL); | |
209 | if (!vecs) | |
210 | return -ENOMEM; | |
211 | } | |
212 | ||
213 | bio_init(&bio, vecs, nr_pages); | |
214 | bio_set_dev(&bio, bdev); | |
215 | bio.bi_iter.bi_sector = pos >> 9; | |
216 | bio.bi_write_hint = iocb->ki_hint; | |
217 | bio.bi_private = current; | |
218 | bio.bi_end_io = blkdev_bio_end_io_simple; | |
219 | ||
220 | ret = bio_iov_iter_get_pages(&bio, iter); | |
221 | if (unlikely(ret)) | |
222 | goto out; | |
223 | ret = bio.bi_iter.bi_size; | |
224 | ||
225 | if (iov_iter_rw(iter) == READ) { | |
226 | bio.bi_opf = REQ_OP_READ; | |
227 | if (iter_is_iovec(iter)) | |
228 | should_dirty = true; | |
229 | } else { | |
230 | bio.bi_opf = dio_bio_write_op(iocb); | |
231 | task_io_account_write(ret); | |
232 | } | |
233 | ||
234 | qc = submit_bio(&bio); | |
235 | for (;;) { | |
236 | set_current_state(TASK_UNINTERRUPTIBLE); | |
237 | if (!READ_ONCE(bio.bi_private)) | |
238 | break; | |
239 | if (!(iocb->ki_flags & IOCB_HIPRI) || | |
240 | !blk_poll(bdev_get_queue(bdev), qc)) | |
241 | io_schedule(); | |
242 | } | |
243 | __set_current_state(TASK_RUNNING); | |
244 | ||
245 | bio_for_each_segment_all(bvec, &bio, i) { | |
246 | if (should_dirty && !PageCompound(bvec->bv_page)) | |
247 | set_page_dirty_lock(bvec->bv_page); | |
248 | put_page(bvec->bv_page); | |
249 | } | |
250 | ||
251 | if (unlikely(bio.bi_status)) | |
252 | ret = blk_status_to_errno(bio.bi_status); | |
253 | ||
254 | out: | |
255 | if (vecs != inline_vecs) | |
256 | kfree(vecs); | |
257 | ||
258 | bio_uninit(&bio); | |
259 | ||
260 | return ret; | |
261 | } | |
262 | ||
263 | struct blkdev_dio { | |
264 | union { | |
265 | struct kiocb *iocb; | |
266 | struct task_struct *waiter; | |
267 | }; | |
268 | size_t size; | |
269 | atomic_t ref; | |
270 | bool multi_bio : 1; | |
271 | bool should_dirty : 1; | |
272 | bool is_sync : 1; | |
273 | struct bio bio; | |
274 | }; | |
275 | ||
276 | static struct bio_set *blkdev_dio_pool __read_mostly; | |
277 | ||
278 | static void blkdev_bio_end_io(struct bio *bio) | |
279 | { | |
280 | struct blkdev_dio *dio = bio->bi_private; | |
281 | bool should_dirty = dio->should_dirty; | |
282 | ||
283 | if (dio->multi_bio && !atomic_dec_and_test(&dio->ref)) { | |
284 | if (bio->bi_status && !dio->bio.bi_status) | |
285 | dio->bio.bi_status = bio->bi_status; | |
286 | } else { | |
287 | if (!dio->is_sync) { | |
288 | struct kiocb *iocb = dio->iocb; | |
289 | ssize_t ret; | |
290 | ||
291 | if (likely(!dio->bio.bi_status)) { | |
292 | ret = dio->size; | |
293 | iocb->ki_pos += ret; | |
294 | } else { | |
295 | ret = blk_status_to_errno(dio->bio.bi_status); | |
296 | } | |
297 | ||
298 | dio->iocb->ki_complete(iocb, ret, 0); | |
299 | bio_put(&dio->bio); | |
300 | } else { | |
301 | struct task_struct *waiter = dio->waiter; | |
302 | ||
303 | WRITE_ONCE(dio->waiter, NULL); | |
304 | wake_up_process(waiter); | |
305 | } | |
306 | } | |
307 | ||
308 | if (should_dirty) { | |
309 | bio_check_pages_dirty(bio); | |
310 | } else { | |
311 | struct bio_vec *bvec; | |
312 | int i; | |
313 | ||
314 | bio_for_each_segment_all(bvec, bio, i) | |
315 | put_page(bvec->bv_page); | |
316 | bio_put(bio); | |
317 | } | |
318 | } | |
319 | ||
320 | static ssize_t | |
321 | __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages) | |
322 | { | |
323 | struct file *file = iocb->ki_filp; | |
324 | struct inode *inode = bdev_file_inode(file); | |
325 | struct block_device *bdev = I_BDEV(inode); | |
326 | struct blk_plug plug; | |
327 | struct blkdev_dio *dio; | |
328 | struct bio *bio; | |
329 | bool is_read = (iov_iter_rw(iter) == READ), is_sync; | |
330 | loff_t pos = iocb->ki_pos; | |
331 | blk_qc_t qc = BLK_QC_T_NONE; | |
332 | int ret = 0; | |
333 | ||
334 | if ((pos | iov_iter_alignment(iter)) & | |
335 | (bdev_logical_block_size(bdev) - 1)) | |
336 | return -EINVAL; | |
337 | ||
338 | bio = bio_alloc_bioset(GFP_KERNEL, nr_pages, blkdev_dio_pool); | |
339 | bio_get(bio); /* extra ref for the completion handler */ | |
340 | ||
341 | dio = container_of(bio, struct blkdev_dio, bio); | |
342 | dio->is_sync = is_sync = is_sync_kiocb(iocb); | |
343 | if (dio->is_sync) | |
344 | dio->waiter = current; | |
345 | else | |
346 | dio->iocb = iocb; | |
347 | ||
348 | dio->size = 0; | |
349 | dio->multi_bio = false; | |
350 | dio->should_dirty = is_read && (iter->type == ITER_IOVEC); | |
351 | ||
352 | blk_start_plug(&plug); | |
353 | for (;;) { | |
354 | bio_set_dev(bio, bdev); | |
355 | bio->bi_iter.bi_sector = pos >> 9; | |
356 | bio->bi_write_hint = iocb->ki_hint; | |
357 | bio->bi_private = dio; | |
358 | bio->bi_end_io = blkdev_bio_end_io; | |
359 | ||
360 | ret = bio_iov_iter_get_pages(bio, iter); | |
361 | if (unlikely(ret)) { | |
362 | bio->bi_status = BLK_STS_IOERR; | |
363 | bio_endio(bio); | |
364 | break; | |
365 | } | |
366 | ||
367 | if (is_read) { | |
368 | bio->bi_opf = REQ_OP_READ; | |
369 | if (dio->should_dirty) | |
370 | bio_set_pages_dirty(bio); | |
371 | } else { | |
372 | bio->bi_opf = dio_bio_write_op(iocb); | |
373 | task_io_account_write(bio->bi_iter.bi_size); | |
374 | } | |
375 | ||
376 | dio->size += bio->bi_iter.bi_size; | |
377 | pos += bio->bi_iter.bi_size; | |
378 | ||
379 | nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES); | |
380 | if (!nr_pages) { | |
381 | qc = submit_bio(bio); | |
382 | break; | |
383 | } | |
384 | ||
385 | if (!dio->multi_bio) { | |
386 | dio->multi_bio = true; | |
387 | atomic_set(&dio->ref, 2); | |
388 | } else { | |
389 | atomic_inc(&dio->ref); | |
390 | } | |
391 | ||
392 | submit_bio(bio); | |
393 | bio = bio_alloc(GFP_KERNEL, nr_pages); | |
394 | } | |
395 | blk_finish_plug(&plug); | |
396 | ||
397 | if (!is_sync) | |
398 | return -EIOCBQUEUED; | |
399 | ||
400 | for (;;) { | |
401 | set_current_state(TASK_UNINTERRUPTIBLE); | |
402 | if (!READ_ONCE(dio->waiter)) | |
403 | break; | |
404 | ||
405 | if (!(iocb->ki_flags & IOCB_HIPRI) || | |
406 | !blk_poll(bdev_get_queue(bdev), qc)) | |
407 | io_schedule(); | |
408 | } | |
409 | __set_current_state(TASK_RUNNING); | |
410 | ||
411 | if (!ret) | |
412 | ret = blk_status_to_errno(dio->bio.bi_status); | |
413 | if (likely(!ret)) | |
414 | ret = dio->size; | |
415 | ||
416 | bio_put(&dio->bio); | |
417 | return ret; | |
418 | } | |
419 | ||
420 | static ssize_t | |
421 | blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter) | |
422 | { | |
423 | int nr_pages; | |
424 | ||
425 | nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES + 1); | |
426 | if (!nr_pages) | |
427 | return 0; | |
428 | if (is_sync_kiocb(iocb) && nr_pages <= BIO_MAX_PAGES) | |
429 | return __blkdev_direct_IO_simple(iocb, iter, nr_pages); | |
430 | ||
431 | return __blkdev_direct_IO(iocb, iter, min(nr_pages, BIO_MAX_PAGES)); | |
432 | } | |
433 | ||
434 | static __init int blkdev_init(void) | |
435 | { | |
436 | blkdev_dio_pool = bioset_create(4, offsetof(struct blkdev_dio, bio), BIOSET_NEED_BVECS); | |
437 | if (!blkdev_dio_pool) | |
438 | return -ENOMEM; | |
439 | return 0; | |
440 | } | |
441 | module_init(blkdev_init); | |
442 | ||
443 | int __sync_blockdev(struct block_device *bdev, int wait) | |
444 | { | |
445 | if (!bdev) | |
446 | return 0; | |
447 | if (!wait) | |
448 | return filemap_flush(bdev->bd_inode->i_mapping); | |
449 | return filemap_write_and_wait(bdev->bd_inode->i_mapping); | |
450 | } | |
451 | ||
452 | /* | |
453 | * Write out and wait upon all the dirty data associated with a block | |
454 | * device via its mapping. Does not take the superblock lock. | |
455 | */ | |
456 | int sync_blockdev(struct block_device *bdev) | |
457 | { | |
458 | return __sync_blockdev(bdev, 1); | |
459 | } | |
460 | EXPORT_SYMBOL(sync_blockdev); | |
461 | ||
462 | /* | |
463 | * Write out and wait upon all dirty data associated with this | |
464 | * device. Filesystem data as well as the underlying block | |
465 | * device. Takes the superblock lock. | |
466 | */ | |
467 | int fsync_bdev(struct block_device *bdev) | |
468 | { | |
469 | struct super_block *sb = get_super(bdev); | |
470 | if (sb) { | |
471 | int res = sync_filesystem(sb); | |
472 | drop_super(sb); | |
473 | return res; | |
474 | } | |
475 | return sync_blockdev(bdev); | |
476 | } | |
477 | EXPORT_SYMBOL(fsync_bdev); | |
478 | ||
479 | /** | |
480 | * freeze_bdev -- lock a filesystem and force it into a consistent state | |
481 | * @bdev: blockdevice to lock | |
482 | * | |
483 | * If a superblock is found on this device, we take the s_umount semaphore | |
484 | * on it to make sure nobody unmounts until the snapshot creation is done. | |
485 | * The reference counter (bd_fsfreeze_count) guarantees that only the last | |
486 | * unfreeze process can unfreeze the frozen filesystem actually when multiple | |
487 | * freeze requests arrive simultaneously. It counts up in freeze_bdev() and | |
488 | * count down in thaw_bdev(). When it becomes 0, thaw_bdev() will unfreeze | |
489 | * actually. | |
490 | */ | |
491 | struct super_block *freeze_bdev(struct block_device *bdev) | |
492 | { | |
493 | struct super_block *sb; | |
494 | int error = 0; | |
495 | ||
496 | mutex_lock(&bdev->bd_fsfreeze_mutex); | |
497 | if (++bdev->bd_fsfreeze_count > 1) { | |
498 | /* | |
499 | * We don't even need to grab a reference - the first call | |
500 | * to freeze_bdev grab an active reference and only the last | |
501 | * thaw_bdev drops it. | |
502 | */ | |
503 | sb = get_super(bdev); | |
504 | if (sb) | |
505 | drop_super(sb); | |
506 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
507 | return sb; | |
508 | } | |
509 | ||
510 | sb = get_active_super(bdev); | |
511 | if (!sb) | |
512 | goto out; | |
513 | if (sb->s_op->freeze_super) | |
514 | error = sb->s_op->freeze_super(sb); | |
515 | else | |
516 | error = freeze_super(sb); | |
517 | if (error) { | |
518 | deactivate_super(sb); | |
519 | bdev->bd_fsfreeze_count--; | |
520 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
521 | return ERR_PTR(error); | |
522 | } | |
523 | deactivate_super(sb); | |
524 | out: | |
525 | sync_blockdev(bdev); | |
526 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
527 | return sb; /* thaw_bdev releases s->s_umount */ | |
528 | } | |
529 | EXPORT_SYMBOL(freeze_bdev); | |
530 | ||
531 | /** | |
532 | * thaw_bdev -- unlock filesystem | |
533 | * @bdev: blockdevice to unlock | |
534 | * @sb: associated superblock | |
535 | * | |
536 | * Unlocks the filesystem and marks it writeable again after freeze_bdev(). | |
537 | */ | |
538 | int thaw_bdev(struct block_device *bdev, struct super_block *sb) | |
539 | { | |
540 | int error = -EINVAL; | |
541 | ||
542 | mutex_lock(&bdev->bd_fsfreeze_mutex); | |
543 | if (!bdev->bd_fsfreeze_count) | |
544 | goto out; | |
545 | ||
546 | error = 0; | |
547 | if (--bdev->bd_fsfreeze_count > 0) | |
548 | goto out; | |
549 | ||
550 | if (!sb) | |
551 | goto out; | |
552 | ||
553 | if (sb->s_op->thaw_super) | |
554 | error = sb->s_op->thaw_super(sb); | |
555 | else | |
556 | error = thaw_super(sb); | |
557 | if (error) | |
558 | bdev->bd_fsfreeze_count++; | |
559 | out: | |
560 | mutex_unlock(&bdev->bd_fsfreeze_mutex); | |
561 | return error; | |
562 | } | |
563 | EXPORT_SYMBOL(thaw_bdev); | |
564 | ||
565 | static int blkdev_writepage(struct page *page, struct writeback_control *wbc) | |
566 | { | |
567 | return block_write_full_page(page, blkdev_get_block, wbc); | |
568 | } | |
569 | ||
570 | static int blkdev_readpage(struct file * file, struct page * page) | |
571 | { | |
572 | return block_read_full_page(page, blkdev_get_block); | |
573 | } | |
574 | ||
575 | static int blkdev_readpages(struct file *file, struct address_space *mapping, | |
576 | struct list_head *pages, unsigned nr_pages) | |
577 | { | |
578 | return mpage_readpages(mapping, pages, nr_pages, blkdev_get_block); | |
579 | } | |
580 | ||
581 | static int blkdev_write_begin(struct file *file, struct address_space *mapping, | |
582 | loff_t pos, unsigned len, unsigned flags, | |
583 | struct page **pagep, void **fsdata) | |
584 | { | |
585 | return block_write_begin(mapping, pos, len, flags, pagep, | |
586 | blkdev_get_block); | |
587 | } | |
588 | ||
589 | static int blkdev_write_end(struct file *file, struct address_space *mapping, | |
590 | loff_t pos, unsigned len, unsigned copied, | |
591 | struct page *page, void *fsdata) | |
592 | { | |
593 | int ret; | |
594 | ret = block_write_end(file, mapping, pos, len, copied, page, fsdata); | |
595 | ||
596 | unlock_page(page); | |
597 | put_page(page); | |
598 | ||
599 | return ret; | |
600 | } | |
601 | ||
602 | /* | |
603 | * private llseek: | |
604 | * for a block special file file_inode(file)->i_size is zero | |
605 | * so we compute the size by hand (just as in block_read/write above) | |
606 | */ | |
607 | static loff_t block_llseek(struct file *file, loff_t offset, int whence) | |
608 | { | |
609 | struct inode *bd_inode = bdev_file_inode(file); | |
610 | loff_t retval; | |
611 | ||
612 | inode_lock(bd_inode); | |
613 | retval = fixed_size_llseek(file, offset, whence, i_size_read(bd_inode)); | |
614 | inode_unlock(bd_inode); | |
615 | return retval; | |
616 | } | |
617 | ||
618 | int blkdev_fsync(struct file *filp, loff_t start, loff_t end, int datasync) | |
619 | { | |
620 | struct inode *bd_inode = bdev_file_inode(filp); | |
621 | struct block_device *bdev = I_BDEV(bd_inode); | |
622 | int error; | |
623 | ||
624 | error = file_write_and_wait_range(filp, start, end); | |
625 | if (error) | |
626 | return error; | |
627 | ||
628 | /* | |
629 | * There is no need to serialise calls to blkdev_issue_flush with | |
630 | * i_mutex and doing so causes performance issues with concurrent | |
631 | * O_SYNC writers to a block device. | |
632 | */ | |
633 | error = blkdev_issue_flush(bdev, GFP_KERNEL, NULL); | |
634 | if (error == -EOPNOTSUPP) | |
635 | error = 0; | |
636 | ||
637 | return error; | |
638 | } | |
639 | EXPORT_SYMBOL(blkdev_fsync); | |
640 | ||
641 | /** | |
642 | * bdev_read_page() - Start reading a page from a block device | |
643 | * @bdev: The device to read the page from | |
644 | * @sector: The offset on the device to read the page to (need not be aligned) | |
645 | * @page: The page to read | |
646 | * | |
647 | * On entry, the page should be locked. It will be unlocked when the page | |
648 | * has been read. If the block driver implements rw_page synchronously, | |
649 | * that will be true on exit from this function, but it need not be. | |
650 | * | |
651 | * Errors returned by this function are usually "soft", eg out of memory, or | |
652 | * queue full; callers should try a different route to read this page rather | |
653 | * than propagate an error back up the stack. | |
654 | * | |
655 | * Return: negative errno if an error occurs, 0 if submission was successful. | |
656 | */ | |
657 | int bdev_read_page(struct block_device *bdev, sector_t sector, | |
658 | struct page *page) | |
659 | { | |
660 | const struct block_device_operations *ops = bdev->bd_disk->fops; | |
661 | int result = -EOPNOTSUPP; | |
662 | ||
663 | if (!ops->rw_page || bdev_get_integrity(bdev)) | |
664 | return result; | |
665 | ||
666 | result = blk_queue_enter(bdev->bd_queue, 0); | |
667 | if (result) | |
668 | return result; | |
669 | result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, false); | |
670 | blk_queue_exit(bdev->bd_queue); | |
671 | return result; | |
672 | } | |
673 | EXPORT_SYMBOL_GPL(bdev_read_page); | |
674 | ||
675 | /** | |
676 | * bdev_write_page() - Start writing a page to a block device | |
677 | * @bdev: The device to write the page to | |
678 | * @sector: The offset on the device to write the page to (need not be aligned) | |
679 | * @page: The page to write | |
680 | * @wbc: The writeback_control for the write | |
681 | * | |
682 | * On entry, the page should be locked and not currently under writeback. | |
683 | * On exit, if the write started successfully, the page will be unlocked and | |
684 | * under writeback. If the write failed already (eg the driver failed to | |
685 | * queue the page to the device), the page will still be locked. If the | |
686 | * caller is a ->writepage implementation, it will need to unlock the page. | |
687 | * | |
688 | * Errors returned by this function are usually "soft", eg out of memory, or | |
689 | * queue full; callers should try a different route to write this page rather | |
690 | * than propagate an error back up the stack. | |
691 | * | |
692 | * Return: negative errno if an error occurs, 0 if submission was successful. | |
693 | */ | |
694 | int bdev_write_page(struct block_device *bdev, sector_t sector, | |
695 | struct page *page, struct writeback_control *wbc) | |
696 | { | |
697 | int result; | |
698 | const struct block_device_operations *ops = bdev->bd_disk->fops; | |
699 | ||
700 | if (!ops->rw_page || bdev_get_integrity(bdev)) | |
701 | return -EOPNOTSUPP; | |
702 | result = blk_queue_enter(bdev->bd_queue, 0); | |
703 | if (result) | |
704 | return result; | |
705 | ||
706 | set_page_writeback(page); | |
707 | result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, true); | |
708 | if (result) { | |
709 | end_page_writeback(page); | |
710 | } else { | |
711 | clean_page_buffers(page); | |
712 | unlock_page(page); | |
713 | } | |
714 | blk_queue_exit(bdev->bd_queue); | |
715 | return result; | |
716 | } | |
717 | EXPORT_SYMBOL_GPL(bdev_write_page); | |
718 | ||
719 | /* | |
720 | * pseudo-fs | |
721 | */ | |
722 | ||
723 | static __cacheline_aligned_in_smp DEFINE_SPINLOCK(bdev_lock); | |
724 | static struct kmem_cache * bdev_cachep __read_mostly; | |
725 | ||
726 | static struct inode *bdev_alloc_inode(struct super_block *sb) | |
727 | { | |
728 | struct bdev_inode *ei = kmem_cache_alloc(bdev_cachep, GFP_KERNEL); | |
729 | if (!ei) | |
730 | return NULL; | |
731 | return &ei->vfs_inode; | |
732 | } | |
733 | ||
734 | static void bdev_i_callback(struct rcu_head *head) | |
735 | { | |
736 | struct inode *inode = container_of(head, struct inode, i_rcu); | |
737 | struct bdev_inode *bdi = BDEV_I(inode); | |
738 | ||
739 | kmem_cache_free(bdev_cachep, bdi); | |
740 | } | |
741 | ||
742 | static void bdev_destroy_inode(struct inode *inode) | |
743 | { | |
744 | call_rcu(&inode->i_rcu, bdev_i_callback); | |
745 | } | |
746 | ||
747 | static void init_once(void *foo) | |
748 | { | |
749 | struct bdev_inode *ei = (struct bdev_inode *) foo; | |
750 | struct block_device *bdev = &ei->bdev; | |
751 | ||
752 | memset(bdev, 0, sizeof(*bdev)); | |
753 | mutex_init(&bdev->bd_mutex); | |
754 | INIT_LIST_HEAD(&bdev->bd_list); | |
755 | #ifdef CONFIG_SYSFS | |
756 | INIT_LIST_HEAD(&bdev->bd_holder_disks); | |
757 | #endif | |
758 | bdev->bd_bdi = &noop_backing_dev_info; | |
759 | inode_init_once(&ei->vfs_inode); | |
760 | /* Initialize mutex for freeze. */ | |
761 | mutex_init(&bdev->bd_fsfreeze_mutex); | |
762 | } | |
763 | ||
764 | static void bdev_evict_inode(struct inode *inode) | |
765 | { | |
766 | struct block_device *bdev = &BDEV_I(inode)->bdev; | |
767 | truncate_inode_pages_final(&inode->i_data); | |
768 | invalidate_inode_buffers(inode); /* is it needed here? */ | |
769 | clear_inode(inode); | |
770 | spin_lock(&bdev_lock); | |
771 | list_del_init(&bdev->bd_list); | |
772 | spin_unlock(&bdev_lock); | |
773 | /* Detach inode from wb early as bdi_put() may free bdi->wb */ | |
774 | inode_detach_wb(inode); | |
775 | if (bdev->bd_bdi != &noop_backing_dev_info) { | |
776 | bdi_put(bdev->bd_bdi); | |
777 | bdev->bd_bdi = &noop_backing_dev_info; | |
778 | } | |
779 | } | |
780 | ||
781 | static const struct super_operations bdev_sops = { | |
782 | .statfs = simple_statfs, | |
783 | .alloc_inode = bdev_alloc_inode, | |
784 | .destroy_inode = bdev_destroy_inode, | |
785 | .drop_inode = generic_delete_inode, | |
786 | .evict_inode = bdev_evict_inode, | |
787 | }; | |
788 | ||
789 | static struct dentry *bd_mount(struct file_system_type *fs_type, | |
790 | int flags, const char *dev_name, void *data) | |
791 | { | |
792 | struct dentry *dent; | |
793 | dent = mount_pseudo(fs_type, "bdev:", &bdev_sops, NULL, BDEVFS_MAGIC); | |
794 | if (!IS_ERR(dent)) | |
795 | dent->d_sb->s_iflags |= SB_I_CGROUPWB; | |
796 | return dent; | |
797 | } | |
798 | ||
799 | static struct file_system_type bd_type = { | |
800 | .name = "bdev", | |
801 | .mount = bd_mount, | |
802 | .kill_sb = kill_anon_super, | |
803 | }; | |
804 | ||
805 | struct super_block *blockdev_superblock __read_mostly; | |
806 | EXPORT_SYMBOL_GPL(blockdev_superblock); | |
807 | ||
808 | void __init bdev_cache_init(void) | |
809 | { | |
810 | int err; | |
811 | static struct vfsmount *bd_mnt; | |
812 | ||
813 | bdev_cachep = kmem_cache_create("bdev_cache", sizeof(struct bdev_inode), | |
814 | 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT| | |
815 | SLAB_MEM_SPREAD|SLAB_ACCOUNT|SLAB_PANIC), | |
816 | init_once); | |
817 | err = register_filesystem(&bd_type); | |
818 | if (err) | |
819 | panic("Cannot register bdev pseudo-fs"); | |
820 | bd_mnt = kern_mount(&bd_type); | |
821 | if (IS_ERR(bd_mnt)) | |
822 | panic("Cannot create bdev pseudo-fs"); | |
823 | blockdev_superblock = bd_mnt->mnt_sb; /* For writeback */ | |
824 | } | |
825 | ||
826 | /* | |
827 | * Most likely _very_ bad one - but then it's hardly critical for small | |
828 | * /dev and can be fixed when somebody will need really large one. | |
829 | * Keep in mind that it will be fed through icache hash function too. | |
830 | */ | |
831 | static inline unsigned long hash(dev_t dev) | |
832 | { | |
833 | return MAJOR(dev)+MINOR(dev); | |
834 | } | |
835 | ||
836 | static int bdev_test(struct inode *inode, void *data) | |
837 | { | |
838 | return BDEV_I(inode)->bdev.bd_dev == *(dev_t *)data; | |
839 | } | |
840 | ||
841 | static int bdev_set(struct inode *inode, void *data) | |
842 | { | |
843 | BDEV_I(inode)->bdev.bd_dev = *(dev_t *)data; | |
844 | return 0; | |
845 | } | |
846 | ||
847 | static LIST_HEAD(all_bdevs); | |
848 | ||
849 | /* | |
850 | * If there is a bdev inode for this device, unhash it so that it gets evicted | |
851 | * as soon as last inode reference is dropped. | |
852 | */ | |
853 | void bdev_unhash_inode(dev_t dev) | |
854 | { | |
855 | struct inode *inode; | |
856 | ||
857 | inode = ilookup5(blockdev_superblock, hash(dev), bdev_test, &dev); | |
858 | if (inode) { | |
859 | remove_inode_hash(inode); | |
860 | iput(inode); | |
861 | } | |
862 | } | |
863 | ||
864 | struct block_device *bdget(dev_t dev) | |
865 | { | |
866 | struct block_device *bdev; | |
867 | struct inode *inode; | |
868 | ||
869 | inode = iget5_locked(blockdev_superblock, hash(dev), | |
870 | bdev_test, bdev_set, &dev); | |
871 | ||
872 | if (!inode) | |
873 | return NULL; | |
874 | ||
875 | bdev = &BDEV_I(inode)->bdev; | |
876 | ||
877 | if (inode->i_state & I_NEW) { | |
878 | bdev->bd_contains = NULL; | |
879 | bdev->bd_super = NULL; | |
880 | bdev->bd_inode = inode; | |
881 | bdev->bd_block_size = i_blocksize(inode); | |
882 | bdev->bd_part_count = 0; | |
883 | bdev->bd_invalidated = 0; | |
884 | inode->i_mode = S_IFBLK; | |
885 | inode->i_rdev = dev; | |
886 | inode->i_bdev = bdev; | |
887 | inode->i_data.a_ops = &def_blk_aops; | |
888 | mapping_set_gfp_mask(&inode->i_data, GFP_USER); | |
889 | spin_lock(&bdev_lock); | |
890 | list_add(&bdev->bd_list, &all_bdevs); | |
891 | spin_unlock(&bdev_lock); | |
892 | unlock_new_inode(inode); | |
893 | } | |
894 | return bdev; | |
895 | } | |
896 | ||
897 | EXPORT_SYMBOL(bdget); | |
898 | ||
899 | /** | |
900 | * bdgrab -- Grab a reference to an already referenced block device | |
901 | * @bdev: Block device to grab a reference to. | |
902 | */ | |
903 | struct block_device *bdgrab(struct block_device *bdev) | |
904 | { | |
905 | ihold(bdev->bd_inode); | |
906 | return bdev; | |
907 | } | |
908 | EXPORT_SYMBOL(bdgrab); | |
909 | ||
910 | long nr_blockdev_pages(void) | |
911 | { | |
912 | struct block_device *bdev; | |
913 | long ret = 0; | |
914 | spin_lock(&bdev_lock); | |
915 | list_for_each_entry(bdev, &all_bdevs, bd_list) { | |
916 | ret += bdev->bd_inode->i_mapping->nrpages; | |
917 | } | |
918 | spin_unlock(&bdev_lock); | |
919 | return ret; | |
920 | } | |
921 | ||
922 | void bdput(struct block_device *bdev) | |
923 | { | |
924 | iput(bdev->bd_inode); | |
925 | } | |
926 | ||
927 | EXPORT_SYMBOL(bdput); | |
928 | ||
929 | static struct block_device *bd_acquire(struct inode *inode) | |
930 | { | |
931 | struct block_device *bdev; | |
932 | ||
933 | spin_lock(&bdev_lock); | |
934 | bdev = inode->i_bdev; | |
935 | if (bdev && !inode_unhashed(bdev->bd_inode)) { | |
936 | bdgrab(bdev); | |
937 | spin_unlock(&bdev_lock); | |
938 | return bdev; | |
939 | } | |
940 | spin_unlock(&bdev_lock); | |
941 | ||
942 | /* | |
943 | * i_bdev references block device inode that was already shut down | |
944 | * (corresponding device got removed). Remove the reference and look | |
945 | * up block device inode again just in case new device got | |
946 | * reestablished under the same device number. | |
947 | */ | |
948 | if (bdev) | |
949 | bd_forget(inode); | |
950 | ||
951 | bdev = bdget(inode->i_rdev); | |
952 | if (bdev) { | |
953 | spin_lock(&bdev_lock); | |
954 | if (!inode->i_bdev) { | |
955 | /* | |
956 | * We take an additional reference to bd_inode, | |
957 | * and it's released in clear_inode() of inode. | |
958 | * So, we can access it via ->i_mapping always | |
959 | * without igrab(). | |
960 | */ | |
961 | bdgrab(bdev); | |
962 | inode->i_bdev = bdev; | |
963 | inode->i_mapping = bdev->bd_inode->i_mapping; | |
964 | } | |
965 | spin_unlock(&bdev_lock); | |
966 | } | |
967 | return bdev; | |
968 | } | |
969 | ||
970 | /* Call when you free inode */ | |
971 | ||
972 | void bd_forget(struct inode *inode) | |
973 | { | |
974 | struct block_device *bdev = NULL; | |
975 | ||
976 | spin_lock(&bdev_lock); | |
977 | if (!sb_is_blkdev_sb(inode->i_sb)) | |
978 | bdev = inode->i_bdev; | |
979 | inode->i_bdev = NULL; | |
980 | inode->i_mapping = &inode->i_data; | |
981 | spin_unlock(&bdev_lock); | |
982 | ||
983 | if (bdev) | |
984 | bdput(bdev); | |
985 | } | |
986 | ||
987 | /** | |
988 | * bd_may_claim - test whether a block device can be claimed | |
989 | * @bdev: block device of interest | |
990 | * @whole: whole block device containing @bdev, may equal @bdev | |
991 | * @holder: holder trying to claim @bdev | |
992 | * | |
993 | * Test whether @bdev can be claimed by @holder. | |
994 | * | |
995 | * CONTEXT: | |
996 | * spin_lock(&bdev_lock). | |
997 | * | |
998 | * RETURNS: | |
999 | * %true if @bdev can be claimed, %false otherwise. | |
1000 | */ | |
1001 | static bool bd_may_claim(struct block_device *bdev, struct block_device *whole, | |
1002 | void *holder) | |
1003 | { | |
1004 | if (bdev->bd_holder == holder) | |
1005 | return true; /* already a holder */ | |
1006 | else if (bdev->bd_holder != NULL) | |
1007 | return false; /* held by someone else */ | |
1008 | else if (whole == bdev) | |
1009 | return true; /* is a whole device which isn't held */ | |
1010 | ||
1011 | else if (whole->bd_holder == bd_may_claim) | |
1012 | return true; /* is a partition of a device that is being partitioned */ | |
1013 | else if (whole->bd_holder != NULL) | |
1014 | return false; /* is a partition of a held device */ | |
1015 | else | |
1016 | return true; /* is a partition of an un-held device */ | |
1017 | } | |
1018 | ||
1019 | /** | |
1020 | * bd_prepare_to_claim - prepare to claim a block device | |
1021 | * @bdev: block device of interest | |
1022 | * @whole: the whole device containing @bdev, may equal @bdev | |
1023 | * @holder: holder trying to claim @bdev | |
1024 | * | |
1025 | * Prepare to claim @bdev. This function fails if @bdev is already | |
1026 | * claimed by another holder and waits if another claiming is in | |
1027 | * progress. This function doesn't actually claim. On successful | |
1028 | * return, the caller has ownership of bd_claiming and bd_holder[s]. | |
1029 | * | |
1030 | * CONTEXT: | |
1031 | * spin_lock(&bdev_lock). Might release bdev_lock, sleep and regrab | |
1032 | * it multiple times. | |
1033 | * | |
1034 | * RETURNS: | |
1035 | * 0 if @bdev can be claimed, -EBUSY otherwise. | |
1036 | */ | |
1037 | static int bd_prepare_to_claim(struct block_device *bdev, | |
1038 | struct block_device *whole, void *holder) | |
1039 | { | |
1040 | retry: | |
1041 | /* if someone else claimed, fail */ | |
1042 | if (!bd_may_claim(bdev, whole, holder)) | |
1043 | return -EBUSY; | |
1044 | ||
1045 | /* if claiming is already in progress, wait for it to finish */ | |
1046 | if (whole->bd_claiming) { | |
1047 | wait_queue_head_t *wq = bit_waitqueue(&whole->bd_claiming, 0); | |
1048 | DEFINE_WAIT(wait); | |
1049 | ||
1050 | prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE); | |
1051 | spin_unlock(&bdev_lock); | |
1052 | schedule(); | |
1053 | finish_wait(wq, &wait); | |
1054 | spin_lock(&bdev_lock); | |
1055 | goto retry; | |
1056 | } | |
1057 | ||
1058 | /* yay, all mine */ | |
1059 | return 0; | |
1060 | } | |
1061 | ||
1062 | /** | |
1063 | * bd_start_claiming - start claiming a block device | |
1064 | * @bdev: block device of interest | |
1065 | * @holder: holder trying to claim @bdev | |
1066 | * | |
1067 | * @bdev is about to be opened exclusively. Check @bdev can be opened | |
1068 | * exclusively and mark that an exclusive open is in progress. Each | |
1069 | * successful call to this function must be matched with a call to | |
1070 | * either bd_finish_claiming() or bd_abort_claiming() (which do not | |
1071 | * fail). | |
1072 | * | |
1073 | * This function is used to gain exclusive access to the block device | |
1074 | * without actually causing other exclusive open attempts to fail. It | |
1075 | * should be used when the open sequence itself requires exclusive | |
1076 | * access but may subsequently fail. | |
1077 | * | |
1078 | * CONTEXT: | |
1079 | * Might sleep. | |
1080 | * | |
1081 | * RETURNS: | |
1082 | * Pointer to the block device containing @bdev on success, ERR_PTR() | |
1083 | * value on failure. | |
1084 | */ | |
1085 | static struct block_device *bd_start_claiming(struct block_device *bdev, | |
1086 | void *holder) | |
1087 | { | |
1088 | struct gendisk *disk; | |
1089 | struct block_device *whole; | |
1090 | int partno, err; | |
1091 | ||
1092 | might_sleep(); | |
1093 | ||
1094 | /* | |
1095 | * @bdev might not have been initialized properly yet, look up | |
1096 | * and grab the outer block device the hard way. | |
1097 | */ | |
1098 | disk = get_gendisk(bdev->bd_dev, &partno); | |
1099 | if (!disk) | |
1100 | return ERR_PTR(-ENXIO); | |
1101 | ||
1102 | /* | |
1103 | * Normally, @bdev should equal what's returned from bdget_disk() | |
1104 | * if partno is 0; however, some drivers (floppy) use multiple | |
1105 | * bdev's for the same physical device and @bdev may be one of the | |
1106 | * aliases. Keep @bdev if partno is 0. This means claimer | |
1107 | * tracking is broken for those devices but it has always been that | |
1108 | * way. | |
1109 | */ | |
1110 | if (partno) | |
1111 | whole = bdget_disk(disk, 0); | |
1112 | else | |
1113 | whole = bdgrab(bdev); | |
1114 | ||
1115 | module_put(disk->fops->owner); | |
1116 | put_disk(disk); | |
1117 | if (!whole) | |
1118 | return ERR_PTR(-ENOMEM); | |
1119 | ||
1120 | /* prepare to claim, if successful, mark claiming in progress */ | |
1121 | spin_lock(&bdev_lock); | |
1122 | ||
1123 | err = bd_prepare_to_claim(bdev, whole, holder); | |
1124 | if (err == 0) { | |
1125 | whole->bd_claiming = holder; | |
1126 | spin_unlock(&bdev_lock); | |
1127 | return whole; | |
1128 | } else { | |
1129 | spin_unlock(&bdev_lock); | |
1130 | bdput(whole); | |
1131 | return ERR_PTR(err); | |
1132 | } | |
1133 | } | |
1134 | ||
1135 | #ifdef CONFIG_SYSFS | |
1136 | struct bd_holder_disk { | |
1137 | struct list_head list; | |
1138 | struct gendisk *disk; | |
1139 | int refcnt; | |
1140 | }; | |
1141 | ||
1142 | static struct bd_holder_disk *bd_find_holder_disk(struct block_device *bdev, | |
1143 | struct gendisk *disk) | |
1144 | { | |
1145 | struct bd_holder_disk *holder; | |
1146 | ||
1147 | list_for_each_entry(holder, &bdev->bd_holder_disks, list) | |
1148 | if (holder->disk == disk) | |
1149 | return holder; | |
1150 | return NULL; | |
1151 | } | |
1152 | ||
1153 | static int add_symlink(struct kobject *from, struct kobject *to) | |
1154 | { | |
1155 | return sysfs_create_link(from, to, kobject_name(to)); | |
1156 | } | |
1157 | ||
1158 | static void del_symlink(struct kobject *from, struct kobject *to) | |
1159 | { | |
1160 | sysfs_remove_link(from, kobject_name(to)); | |
1161 | } | |
1162 | ||
1163 | /** | |
1164 | * bd_link_disk_holder - create symlinks between holding disk and slave bdev | |
1165 | * @bdev: the claimed slave bdev | |
1166 | * @disk: the holding disk | |
1167 | * | |
1168 | * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. | |
1169 | * | |
1170 | * This functions creates the following sysfs symlinks. | |
1171 | * | |
1172 | * - from "slaves" directory of the holder @disk to the claimed @bdev | |
1173 | * - from "holders" directory of the @bdev to the holder @disk | |
1174 | * | |
1175 | * For example, if /dev/dm-0 maps to /dev/sda and disk for dm-0 is | |
1176 | * passed to bd_link_disk_holder(), then: | |
1177 | * | |
1178 | * /sys/block/dm-0/slaves/sda --> /sys/block/sda | |
1179 | * /sys/block/sda/holders/dm-0 --> /sys/block/dm-0 | |
1180 | * | |
1181 | * The caller must have claimed @bdev before calling this function and | |
1182 | * ensure that both @bdev and @disk are valid during the creation and | |
1183 | * lifetime of these symlinks. | |
1184 | * | |
1185 | * CONTEXT: | |
1186 | * Might sleep. | |
1187 | * | |
1188 | * RETURNS: | |
1189 | * 0 on success, -errno on failure. | |
1190 | */ | |
1191 | int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk) | |
1192 | { | |
1193 | struct bd_holder_disk *holder; | |
1194 | int ret = 0; | |
1195 | ||
1196 | mutex_lock(&bdev->bd_mutex); | |
1197 | ||
1198 | WARN_ON_ONCE(!bdev->bd_holder); | |
1199 | ||
1200 | /* FIXME: remove the following once add_disk() handles errors */ | |
1201 | if (WARN_ON(!disk->slave_dir || !bdev->bd_part->holder_dir)) | |
1202 | goto out_unlock; | |
1203 | ||
1204 | holder = bd_find_holder_disk(bdev, disk); | |
1205 | if (holder) { | |
1206 | holder->refcnt++; | |
1207 | goto out_unlock; | |
1208 | } | |
1209 | ||
1210 | holder = kzalloc(sizeof(*holder), GFP_KERNEL); | |
1211 | if (!holder) { | |
1212 | ret = -ENOMEM; | |
1213 | goto out_unlock; | |
1214 | } | |
1215 | ||
1216 | INIT_LIST_HEAD(&holder->list); | |
1217 | holder->disk = disk; | |
1218 | holder->refcnt = 1; | |
1219 | ||
1220 | ret = add_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); | |
1221 | if (ret) | |
1222 | goto out_free; | |
1223 | ||
1224 | ret = add_symlink(bdev->bd_part->holder_dir, &disk_to_dev(disk)->kobj); | |
1225 | if (ret) | |
1226 | goto out_del; | |
1227 | /* | |
1228 | * bdev could be deleted beneath us which would implicitly destroy | |
1229 | * the holder directory. Hold on to it. | |
1230 | */ | |
1231 | kobject_get(bdev->bd_part->holder_dir); | |
1232 | ||
1233 | list_add(&holder->list, &bdev->bd_holder_disks); | |
1234 | goto out_unlock; | |
1235 | ||
1236 | out_del: | |
1237 | del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); | |
1238 | out_free: | |
1239 | kfree(holder); | |
1240 | out_unlock: | |
1241 | mutex_unlock(&bdev->bd_mutex); | |
1242 | return ret; | |
1243 | } | |
1244 | EXPORT_SYMBOL_GPL(bd_link_disk_holder); | |
1245 | ||
1246 | /** | |
1247 | * bd_unlink_disk_holder - destroy symlinks created by bd_link_disk_holder() | |
1248 | * @bdev: the calimed slave bdev | |
1249 | * @disk: the holding disk | |
1250 | * | |
1251 | * DON'T USE THIS UNLESS YOU'RE ALREADY USING IT. | |
1252 | * | |
1253 | * CONTEXT: | |
1254 | * Might sleep. | |
1255 | */ | |
1256 | void bd_unlink_disk_holder(struct block_device *bdev, struct gendisk *disk) | |
1257 | { | |
1258 | struct bd_holder_disk *holder; | |
1259 | ||
1260 | mutex_lock(&bdev->bd_mutex); | |
1261 | ||
1262 | holder = bd_find_holder_disk(bdev, disk); | |
1263 | ||
1264 | if (!WARN_ON_ONCE(holder == NULL) && !--holder->refcnt) { | |
1265 | del_symlink(disk->slave_dir, &part_to_dev(bdev->bd_part)->kobj); | |
1266 | del_symlink(bdev->bd_part->holder_dir, | |
1267 | &disk_to_dev(disk)->kobj); | |
1268 | kobject_put(bdev->bd_part->holder_dir); | |
1269 | list_del_init(&holder->list); | |
1270 | kfree(holder); | |
1271 | } | |
1272 | ||
1273 | mutex_unlock(&bdev->bd_mutex); | |
1274 | } | |
1275 | EXPORT_SYMBOL_GPL(bd_unlink_disk_holder); | |
1276 | #endif | |
1277 | ||
1278 | /** | |
1279 | * flush_disk - invalidates all buffer-cache entries on a disk | |
1280 | * | |
1281 | * @bdev: struct block device to be flushed | |
1282 | * @kill_dirty: flag to guide handling of dirty inodes | |
1283 | * | |
1284 | * Invalidates all buffer-cache entries on a disk. It should be called | |
1285 | * when a disk has been changed -- either by a media change or online | |
1286 | * resize. | |
1287 | */ | |
1288 | static void flush_disk(struct block_device *bdev, bool kill_dirty) | |
1289 | { | |
1290 | if (__invalidate_device(bdev, kill_dirty)) { | |
1291 | printk(KERN_WARNING "VFS: busy inodes on changed media or " | |
1292 | "resized disk %s\n", | |
1293 | bdev->bd_disk ? bdev->bd_disk->disk_name : ""); | |
1294 | } | |
1295 | ||
1296 | if (!bdev->bd_disk) | |
1297 | return; | |
1298 | if (disk_part_scan_enabled(bdev->bd_disk)) | |
1299 | bdev->bd_invalidated = 1; | |
1300 | } | |
1301 | ||
1302 | /** | |
1303 | * check_disk_size_change - checks for disk size change and adjusts bdev size. | |
1304 | * @disk: struct gendisk to check | |
1305 | * @bdev: struct bdev to adjust. | |
1306 | * | |
1307 | * This routine checks to see if the bdev size does not match the disk size | |
1308 | * and adjusts it if it differs. | |
1309 | */ | |
1310 | void check_disk_size_change(struct gendisk *disk, struct block_device *bdev) | |
1311 | { | |
1312 | loff_t disk_size, bdev_size; | |
1313 | ||
1314 | disk_size = (loff_t)get_capacity(disk) << 9; | |
1315 | bdev_size = i_size_read(bdev->bd_inode); | |
1316 | if (disk_size != bdev_size) { | |
1317 | printk(KERN_INFO | |
1318 | "%s: detected capacity change from %lld to %lld\n", | |
1319 | disk->disk_name, bdev_size, disk_size); | |
1320 | i_size_write(bdev->bd_inode, disk_size); | |
1321 | flush_disk(bdev, false); | |
1322 | } | |
1323 | } | |
1324 | EXPORT_SYMBOL(check_disk_size_change); | |
1325 | ||
1326 | /** | |
1327 | * revalidate_disk - wrapper for lower-level driver's revalidate_disk call-back | |
1328 | * @disk: struct gendisk to be revalidated | |
1329 | * | |
1330 | * This routine is a wrapper for lower-level driver's revalidate_disk | |
1331 | * call-backs. It is used to do common pre and post operations needed | |
1332 | * for all revalidate_disk operations. | |
1333 | */ | |
1334 | int revalidate_disk(struct gendisk *disk) | |
1335 | { | |
1336 | struct block_device *bdev; | |
1337 | int ret = 0; | |
1338 | ||
1339 | if (disk->fops->revalidate_disk) | |
1340 | ret = disk->fops->revalidate_disk(disk); | |
1341 | bdev = bdget_disk(disk, 0); | |
1342 | if (!bdev) | |
1343 | return ret; | |
1344 | ||
1345 | mutex_lock(&bdev->bd_mutex); | |
1346 | check_disk_size_change(disk, bdev); | |
1347 | bdev->bd_invalidated = 0; | |
1348 | mutex_unlock(&bdev->bd_mutex); | |
1349 | bdput(bdev); | |
1350 | return ret; | |
1351 | } | |
1352 | EXPORT_SYMBOL(revalidate_disk); | |
1353 | ||
1354 | /* | |
1355 | * This routine checks whether a removable media has been changed, | |
1356 | * and invalidates all buffer-cache-entries in that case. This | |
1357 | * is a relatively slow routine, so we have to try to minimize using | |
1358 | * it. Thus it is called only upon a 'mount' or 'open'. This | |
1359 | * is the best way of combining speed and utility, I think. | |
1360 | * People changing diskettes in the middle of an operation deserve | |
1361 | * to lose :-) | |
1362 | */ | |
1363 | int check_disk_change(struct block_device *bdev) | |
1364 | { | |
1365 | struct gendisk *disk = bdev->bd_disk; | |
1366 | const struct block_device_operations *bdops = disk->fops; | |
1367 | unsigned int events; | |
1368 | ||
1369 | events = disk_clear_events(disk, DISK_EVENT_MEDIA_CHANGE | | |
1370 | DISK_EVENT_EJECT_REQUEST); | |
1371 | if (!(events & DISK_EVENT_MEDIA_CHANGE)) | |
1372 | return 0; | |
1373 | ||
1374 | flush_disk(bdev, true); | |
1375 | if (bdops->revalidate_disk) | |
1376 | bdops->revalidate_disk(bdev->bd_disk); | |
1377 | return 1; | |
1378 | } | |
1379 | ||
1380 | EXPORT_SYMBOL(check_disk_change); | |
1381 | ||
1382 | void bd_set_size(struct block_device *bdev, loff_t size) | |
1383 | { | |
1384 | unsigned bsize = bdev_logical_block_size(bdev); | |
1385 | ||
1386 | inode_lock(bdev->bd_inode); | |
1387 | i_size_write(bdev->bd_inode, size); | |
1388 | inode_unlock(bdev->bd_inode); | |
1389 | while (bsize < PAGE_SIZE) { | |
1390 | if (size & bsize) | |
1391 | break; | |
1392 | bsize <<= 1; | |
1393 | } | |
1394 | bdev->bd_block_size = bsize; | |
1395 | bdev->bd_inode->i_blkbits = blksize_bits(bsize); | |
1396 | } | |
1397 | EXPORT_SYMBOL(bd_set_size); | |
1398 | ||
1399 | static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part); | |
1400 | ||
1401 | /* | |
1402 | * bd_mutex locking: | |
1403 | * | |
1404 | * mutex_lock(part->bd_mutex) | |
1405 | * mutex_lock_nested(whole->bd_mutex, 1) | |
1406 | */ | |
1407 | ||
1408 | static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part) | |
1409 | { | |
1410 | struct gendisk *disk; | |
1411 | struct module *owner; | |
1412 | int ret; | |
1413 | int partno; | |
1414 | int perm = 0; | |
1415 | ||
1416 | if (mode & FMODE_READ) | |
1417 | perm |= MAY_READ; | |
1418 | if (mode & FMODE_WRITE) | |
1419 | perm |= MAY_WRITE; | |
1420 | /* | |
1421 | * hooks: /n/, see "layering violations". | |
1422 | */ | |
1423 | if (!for_part) { | |
1424 | ret = devcgroup_inode_permission(bdev->bd_inode, perm); | |
1425 | if (ret != 0) { | |
1426 | bdput(bdev); | |
1427 | return ret; | |
1428 | } | |
1429 | } | |
1430 | ||
1431 | restart: | |
1432 | ||
1433 | ret = -ENXIO; | |
1434 | disk = get_gendisk(bdev->bd_dev, &partno); | |
1435 | if (!disk) | |
1436 | goto out; | |
1437 | owner = disk->fops->owner; | |
1438 | ||
1439 | disk_block_events(disk); | |
1440 | mutex_lock_nested(&bdev->bd_mutex, for_part); | |
1441 | if (!bdev->bd_openers) { | |
1442 | bdev->bd_disk = disk; | |
1443 | bdev->bd_queue = disk->queue; | |
1444 | bdev->bd_contains = bdev; | |
1445 | bdev->bd_partno = partno; | |
1446 | ||
1447 | if (!partno) { | |
1448 | ret = -ENXIO; | |
1449 | bdev->bd_part = disk_get_part(disk, partno); | |
1450 | if (!bdev->bd_part) | |
1451 | goto out_clear; | |
1452 | ||
1453 | ret = 0; | |
1454 | if (disk->fops->open) { | |
1455 | ret = disk->fops->open(bdev, mode); | |
1456 | if (ret == -ERESTARTSYS) { | |
1457 | /* Lost a race with 'disk' being | |
1458 | * deleted, try again. | |
1459 | * See md.c | |
1460 | */ | |
1461 | disk_put_part(bdev->bd_part); | |
1462 | bdev->bd_part = NULL; | |
1463 | bdev->bd_disk = NULL; | |
1464 | bdev->bd_queue = NULL; | |
1465 | mutex_unlock(&bdev->bd_mutex); | |
1466 | disk_unblock_events(disk); | |
1467 | put_disk(disk); | |
1468 | module_put(owner); | |
1469 | goto restart; | |
1470 | } | |
1471 | } | |
1472 | ||
1473 | if (!ret) | |
1474 | bd_set_size(bdev,(loff_t)get_capacity(disk)<<9); | |
1475 | ||
1476 | /* | |
1477 | * If the device is invalidated, rescan partition | |
1478 | * if open succeeded or failed with -ENOMEDIUM. | |
1479 | * The latter is necessary to prevent ghost | |
1480 | * partitions on a removed medium. | |
1481 | */ | |
1482 | if (bdev->bd_invalidated) { | |
1483 | if (!ret) | |
1484 | rescan_partitions(disk, bdev); | |
1485 | else if (ret == -ENOMEDIUM) | |
1486 | invalidate_partitions(disk, bdev); | |
1487 | } | |
1488 | ||
1489 | if (ret) | |
1490 | goto out_clear; | |
1491 | } else { | |
1492 | struct block_device *whole; | |
1493 | whole = bdget_disk(disk, 0); | |
1494 | ret = -ENOMEM; | |
1495 | if (!whole) | |
1496 | goto out_clear; | |
1497 | BUG_ON(for_part); | |
1498 | ret = __blkdev_get(whole, mode, 1); | |
1499 | if (ret) | |
1500 | goto out_clear; | |
1501 | bdev->bd_contains = whole; | |
1502 | bdev->bd_part = disk_get_part(disk, partno); | |
1503 | if (!(disk->flags & GENHD_FL_UP) || | |
1504 | !bdev->bd_part || !bdev->bd_part->nr_sects) { | |
1505 | ret = -ENXIO; | |
1506 | goto out_clear; | |
1507 | } | |
1508 | bd_set_size(bdev, (loff_t)bdev->bd_part->nr_sects << 9); | |
1509 | } | |
1510 | ||
1511 | if (bdev->bd_bdi == &noop_backing_dev_info) | |
1512 | bdev->bd_bdi = bdi_get(disk->queue->backing_dev_info); | |
1513 | } else { | |
1514 | if (bdev->bd_contains == bdev) { | |
1515 | ret = 0; | |
1516 | if (bdev->bd_disk->fops->open) | |
1517 | ret = bdev->bd_disk->fops->open(bdev, mode); | |
1518 | /* the same as first opener case, read comment there */ | |
1519 | if (bdev->bd_invalidated) { | |
1520 | if (!ret) | |
1521 | rescan_partitions(bdev->bd_disk, bdev); | |
1522 | else if (ret == -ENOMEDIUM) | |
1523 | invalidate_partitions(bdev->bd_disk, bdev); | |
1524 | } | |
1525 | if (ret) | |
1526 | goto out_unlock_bdev; | |
1527 | } | |
1528 | /* only one opener holds refs to the module and disk */ | |
1529 | put_disk(disk); | |
1530 | module_put(owner); | |
1531 | } | |
1532 | bdev->bd_openers++; | |
1533 | if (for_part) | |
1534 | bdev->bd_part_count++; | |
1535 | mutex_unlock(&bdev->bd_mutex); | |
1536 | disk_unblock_events(disk); | |
1537 | return 0; | |
1538 | ||
1539 | out_clear: | |
1540 | disk_put_part(bdev->bd_part); | |
1541 | bdev->bd_disk = NULL; | |
1542 | bdev->bd_part = NULL; | |
1543 | bdev->bd_queue = NULL; | |
1544 | if (bdev != bdev->bd_contains) | |
1545 | __blkdev_put(bdev->bd_contains, mode, 1); | |
1546 | bdev->bd_contains = NULL; | |
1547 | out_unlock_bdev: | |
1548 | mutex_unlock(&bdev->bd_mutex); | |
1549 | disk_unblock_events(disk); | |
1550 | put_disk(disk); | |
1551 | module_put(owner); | |
1552 | out: | |
1553 | bdput(bdev); | |
1554 | ||
1555 | return ret; | |
1556 | } | |
1557 | ||
1558 | /** | |
1559 | * blkdev_get - open a block device | |
1560 | * @bdev: block_device to open | |
1561 | * @mode: FMODE_* mask | |
1562 | * @holder: exclusive holder identifier | |
1563 | * | |
1564 | * Open @bdev with @mode. If @mode includes %FMODE_EXCL, @bdev is | |
1565 | * open with exclusive access. Specifying %FMODE_EXCL with %NULL | |
1566 | * @holder is invalid. Exclusive opens may nest for the same @holder. | |
1567 | * | |
1568 | * On success, the reference count of @bdev is unchanged. On failure, | |
1569 | * @bdev is put. | |
1570 | * | |
1571 | * CONTEXT: | |
1572 | * Might sleep. | |
1573 | * | |
1574 | * RETURNS: | |
1575 | * 0 on success, -errno on failure. | |
1576 | */ | |
1577 | int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder) | |
1578 | { | |
1579 | struct block_device *whole = NULL; | |
1580 | int res; | |
1581 | ||
1582 | WARN_ON_ONCE((mode & FMODE_EXCL) && !holder); | |
1583 | ||
1584 | if ((mode & FMODE_EXCL) && holder) { | |
1585 | whole = bd_start_claiming(bdev, holder); | |
1586 | if (IS_ERR(whole)) { | |
1587 | bdput(bdev); | |
1588 | return PTR_ERR(whole); | |
1589 | } | |
1590 | } | |
1591 | ||
1592 | res = __blkdev_get(bdev, mode, 0); | |
1593 | ||
1594 | if (whole) { | |
1595 | struct gendisk *disk = whole->bd_disk; | |
1596 | ||
1597 | /* finish claiming */ | |
1598 | mutex_lock(&bdev->bd_mutex); | |
1599 | spin_lock(&bdev_lock); | |
1600 | ||
1601 | if (!res) { | |
1602 | BUG_ON(!bd_may_claim(bdev, whole, holder)); | |
1603 | /* | |
1604 | * Note that for a whole device bd_holders | |
1605 | * will be incremented twice, and bd_holder | |
1606 | * will be set to bd_may_claim before being | |
1607 | * set to holder | |
1608 | */ | |
1609 | whole->bd_holders++; | |
1610 | whole->bd_holder = bd_may_claim; | |
1611 | bdev->bd_holders++; | |
1612 | bdev->bd_holder = holder; | |
1613 | } | |
1614 | ||
1615 | /* tell others that we're done */ | |
1616 | BUG_ON(whole->bd_claiming != holder); | |
1617 | whole->bd_claiming = NULL; | |
1618 | wake_up_bit(&whole->bd_claiming, 0); | |
1619 | ||
1620 | spin_unlock(&bdev_lock); | |
1621 | ||
1622 | /* | |
1623 | * Block event polling for write claims if requested. Any | |
1624 | * write holder makes the write_holder state stick until | |
1625 | * all are released. This is good enough and tracking | |
1626 | * individual writeable reference is too fragile given the | |
1627 | * way @mode is used in blkdev_get/put(). | |
1628 | */ | |
1629 | if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder && | |
1630 | (disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE)) { | |
1631 | bdev->bd_write_holder = true; | |
1632 | disk_block_events(disk); | |
1633 | } | |
1634 | ||
1635 | mutex_unlock(&bdev->bd_mutex); | |
1636 | bdput(whole); | |
1637 | } | |
1638 | ||
1639 | return res; | |
1640 | } | |
1641 | EXPORT_SYMBOL(blkdev_get); | |
1642 | ||
1643 | /** | |
1644 | * blkdev_get_by_path - open a block device by name | |
1645 | * @path: path to the block device to open | |
1646 | * @mode: FMODE_* mask | |
1647 | * @holder: exclusive holder identifier | |
1648 | * | |
1649 | * Open the blockdevice described by the device file at @path. @mode | |
1650 | * and @holder are identical to blkdev_get(). | |
1651 | * | |
1652 | * On success, the returned block_device has reference count of one. | |
1653 | * | |
1654 | * CONTEXT: | |
1655 | * Might sleep. | |
1656 | * | |
1657 | * RETURNS: | |
1658 | * Pointer to block_device on success, ERR_PTR(-errno) on failure. | |
1659 | */ | |
1660 | struct block_device *blkdev_get_by_path(const char *path, fmode_t mode, | |
1661 | void *holder) | |
1662 | { | |
1663 | struct block_device *bdev; | |
1664 | int perm = 0; | |
1665 | int err; | |
1666 | ||
1667 | if (mode & FMODE_READ) | |
1668 | perm |= MAY_READ; | |
1669 | if (mode & FMODE_WRITE) | |
1670 | perm |= MAY_WRITE; | |
1671 | bdev = lookup_bdev(path, perm); | |
1672 | if (IS_ERR(bdev)) | |
1673 | return bdev; | |
1674 | ||
1675 | err = blkdev_get(bdev, mode, holder); | |
1676 | if (err) | |
1677 | return ERR_PTR(err); | |
1678 | ||
1679 | if ((mode & FMODE_WRITE) && bdev_read_only(bdev)) { | |
1680 | blkdev_put(bdev, mode); | |
1681 | return ERR_PTR(-EACCES); | |
1682 | } | |
1683 | ||
1684 | return bdev; | |
1685 | } | |
1686 | EXPORT_SYMBOL(blkdev_get_by_path); | |
1687 | ||
1688 | /** | |
1689 | * blkdev_get_by_dev - open a block device by device number | |
1690 | * @dev: device number of block device to open | |
1691 | * @mode: FMODE_* mask | |
1692 | * @holder: exclusive holder identifier | |
1693 | * | |
1694 | * Open the blockdevice described by device number @dev. @mode and | |
1695 | * @holder are identical to blkdev_get(). | |
1696 | * | |
1697 | * Use it ONLY if you really do not have anything better - i.e. when | |
1698 | * you are behind a truly sucky interface and all you are given is a | |
1699 | * device number. _Never_ to be used for internal purposes. If you | |
1700 | * ever need it - reconsider your API. | |
1701 | * | |
1702 | * On success, the returned block_device has reference count of one. | |
1703 | * | |
1704 | * CONTEXT: | |
1705 | * Might sleep. | |
1706 | * | |
1707 | * RETURNS: | |
1708 | * Pointer to block_device on success, ERR_PTR(-errno) on failure. | |
1709 | */ | |
1710 | struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode, void *holder) | |
1711 | { | |
1712 | struct block_device *bdev; | |
1713 | int err; | |
1714 | ||
1715 | bdev = bdget(dev); | |
1716 | if (!bdev) | |
1717 | return ERR_PTR(-ENOMEM); | |
1718 | ||
1719 | err = blkdev_get(bdev, mode, holder); | |
1720 | if (err) | |
1721 | return ERR_PTR(err); | |
1722 | ||
1723 | return bdev; | |
1724 | } | |
1725 | EXPORT_SYMBOL(blkdev_get_by_dev); | |
1726 | ||
1727 | static int blkdev_open(struct inode * inode, struct file * filp) | |
1728 | { | |
1729 | struct block_device *bdev; | |
1730 | ||
1731 | /* | |
1732 | * Preserve backwards compatibility and allow large file access | |
1733 | * even if userspace doesn't ask for it explicitly. Some mkfs | |
1734 | * binary needs it. We might want to drop this workaround | |
1735 | * during an unstable branch. | |
1736 | */ | |
1737 | filp->f_flags |= O_LARGEFILE; | |
1738 | ||
1739 | filp->f_mode |= FMODE_NOWAIT; | |
1740 | ||
1741 | if (filp->f_flags & O_NDELAY) | |
1742 | filp->f_mode |= FMODE_NDELAY; | |
1743 | if (filp->f_flags & O_EXCL) | |
1744 | filp->f_mode |= FMODE_EXCL; | |
1745 | if ((filp->f_flags & O_ACCMODE) == 3) | |
1746 | filp->f_mode |= FMODE_WRITE_IOCTL; | |
1747 | ||
1748 | bdev = bd_acquire(inode); | |
1749 | if (bdev == NULL) | |
1750 | return -ENOMEM; | |
1751 | ||
1752 | /* | |
1753 | * A negative i_writecount for bdev->bd_inode means that the bdev | |
1754 | * or one of its paritions is mounted in a user namespace. Deny | |
1755 | * writing for non-root in this case, otherwise an unprivileged | |
1756 | * user can attack the kernel by modifying the backing store of a | |
1757 | * mounted filesystem. | |
1758 | */ | |
1759 | if ((filp->f_mode & FMODE_WRITE) && | |
1760 | !file_ns_capable(filp, &init_user_ns, CAP_SYS_ADMIN) && | |
1761 | !atomic_inc_unless_negative(&bdev->bd_inode->i_writecount)) { | |
1762 | bdput(bdev); | |
1763 | return -EBUSY; | |
1764 | } | |
1765 | ||
1766 | filp->f_mapping = bdev->bd_inode->i_mapping; | |
1767 | filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping); | |
1768 | ||
1769 | return blkdev_get(bdev, filp->f_mode, filp); | |
1770 | } | |
1771 | ||
1772 | static void __blkdev_put(struct block_device *bdev, fmode_t mode, int for_part) | |
1773 | { | |
1774 | struct gendisk *disk = bdev->bd_disk; | |
1775 | struct block_device *victim = NULL; | |
1776 | ||
1777 | mutex_lock_nested(&bdev->bd_mutex, for_part); | |
1778 | if (for_part) | |
1779 | bdev->bd_part_count--; | |
1780 | ||
1781 | if (!--bdev->bd_openers) { | |
1782 | WARN_ON_ONCE(bdev->bd_holders); | |
1783 | sync_blockdev(bdev); | |
1784 | kill_bdev(bdev); | |
1785 | ||
1786 | bdev_write_inode(bdev); | |
1787 | } | |
1788 | if (bdev->bd_contains == bdev) { | |
1789 | if (disk->fops->release) | |
1790 | disk->fops->release(disk, mode); | |
1791 | } | |
1792 | if (!bdev->bd_openers) { | |
1793 | struct module *owner = disk->fops->owner; | |
1794 | ||
1795 | disk_put_part(bdev->bd_part); | |
1796 | bdev->bd_part = NULL; | |
1797 | bdev->bd_disk = NULL; | |
1798 | if (bdev != bdev->bd_contains) | |
1799 | victim = bdev->bd_contains; | |
1800 | bdev->bd_contains = NULL; | |
1801 | ||
1802 | put_disk(disk); | |
1803 | module_put(owner); | |
1804 | } | |
1805 | mutex_unlock(&bdev->bd_mutex); | |
1806 | bdput(bdev); | |
1807 | if (victim) | |
1808 | __blkdev_put(victim, mode, 1); | |
1809 | } | |
1810 | ||
1811 | void blkdev_put(struct block_device *bdev, fmode_t mode) | |
1812 | { | |
1813 | mutex_lock(&bdev->bd_mutex); | |
1814 | ||
1815 | if (mode & FMODE_EXCL) { | |
1816 | bool bdev_free; | |
1817 | ||
1818 | /* | |
1819 | * Release a claim on the device. The holder fields | |
1820 | * are protected with bdev_lock. bd_mutex is to | |
1821 | * synchronize disk_holder unlinking. | |
1822 | */ | |
1823 | spin_lock(&bdev_lock); | |
1824 | ||
1825 | WARN_ON_ONCE(--bdev->bd_holders < 0); | |
1826 | WARN_ON_ONCE(--bdev->bd_contains->bd_holders < 0); | |
1827 | ||
1828 | /* bd_contains might point to self, check in a separate step */ | |
1829 | if ((bdev_free = !bdev->bd_holders)) | |
1830 | bdev->bd_holder = NULL; | |
1831 | if (!bdev->bd_contains->bd_holders) | |
1832 | bdev->bd_contains->bd_holder = NULL; | |
1833 | ||
1834 | spin_unlock(&bdev_lock); | |
1835 | ||
1836 | /* | |
1837 | * If this was the last claim, remove holder link and | |
1838 | * unblock evpoll if it was a write holder. | |
1839 | */ | |
1840 | if (bdev_free && bdev->bd_write_holder) { | |
1841 | disk_unblock_events(bdev->bd_disk); | |
1842 | bdev->bd_write_holder = false; | |
1843 | } | |
1844 | } | |
1845 | ||
1846 | /* | |
1847 | * Trigger event checking and tell drivers to flush MEDIA_CHANGE | |
1848 | * event. This is to ensure detection of media removal commanded | |
1849 | * from userland - e.g. eject(1). | |
1850 | */ | |
1851 | disk_flush_events(bdev->bd_disk, DISK_EVENT_MEDIA_CHANGE); | |
1852 | ||
1853 | mutex_unlock(&bdev->bd_mutex); | |
1854 | ||
1855 | __blkdev_put(bdev, mode, 0); | |
1856 | } | |
1857 | EXPORT_SYMBOL(blkdev_put); | |
1858 | ||
1859 | static int blkdev_close(struct inode * inode, struct file * filp) | |
1860 | { | |
1861 | struct block_device *bdev = I_BDEV(bdev_file_inode(filp)); | |
1862 | if (filp->f_mode & FMODE_WRITE && | |
1863 | !file_ns_capable(filp, &init_user_ns, CAP_SYS_ADMIN)) | |
1864 | atomic_dec(&bdev->bd_inode->i_writecount); | |
1865 | blkdev_put(bdev, filp->f_mode); | |
1866 | return 0; | |
1867 | } | |
1868 | ||
1869 | static long block_ioctl(struct file *file, unsigned cmd, unsigned long arg) | |
1870 | { | |
1871 | struct block_device *bdev = I_BDEV(bdev_file_inode(file)); | |
1872 | fmode_t mode = file->f_mode; | |
1873 | ||
1874 | /* | |
1875 | * O_NDELAY can be altered using fcntl(.., F_SETFL, ..), so we have | |
1876 | * to updated it before every ioctl. | |
1877 | */ | |
1878 | if (file->f_flags & O_NDELAY) | |
1879 | mode |= FMODE_NDELAY; | |
1880 | else | |
1881 | mode &= ~FMODE_NDELAY; | |
1882 | ||
1883 | return blkdev_ioctl(bdev, mode, cmd, arg); | |
1884 | } | |
1885 | ||
1886 | /* | |
1887 | * Write data to the block device. Only intended for the block device itself | |
1888 | * and the raw driver which basically is a fake block device. | |
1889 | * | |
1890 | * Does not take i_mutex for the write and thus is not for general purpose | |
1891 | * use. | |
1892 | */ | |
1893 | ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from) | |
1894 | { | |
1895 | struct file *file = iocb->ki_filp; | |
1896 | struct inode *bd_inode = bdev_file_inode(file); | |
1897 | loff_t size = i_size_read(bd_inode); | |
1898 | struct blk_plug plug; | |
1899 | ssize_t ret; | |
1900 | ||
1901 | if (bdev_read_only(I_BDEV(bd_inode))) | |
1902 | return -EPERM; | |
1903 | ||
1904 | if (!iov_iter_count(from)) | |
1905 | return 0; | |
1906 | ||
1907 | if (iocb->ki_pos >= size) | |
1908 | return -ENOSPC; | |
1909 | ||
1910 | if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT) | |
1911 | return -EOPNOTSUPP; | |
1912 | ||
1913 | iov_iter_truncate(from, size - iocb->ki_pos); | |
1914 | ||
1915 | blk_start_plug(&plug); | |
1916 | ret = __generic_file_write_iter(iocb, from); | |
1917 | if (ret > 0) | |
1918 | ret = generic_write_sync(iocb, ret); | |
1919 | blk_finish_plug(&plug); | |
1920 | return ret; | |
1921 | } | |
1922 | EXPORT_SYMBOL_GPL(blkdev_write_iter); | |
1923 | ||
1924 | ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to) | |
1925 | { | |
1926 | struct file *file = iocb->ki_filp; | |
1927 | struct inode *bd_inode = bdev_file_inode(file); | |
1928 | loff_t size = i_size_read(bd_inode); | |
1929 | loff_t pos = iocb->ki_pos; | |
1930 | ||
1931 | if (pos >= size) | |
1932 | return 0; | |
1933 | ||
1934 | size -= pos; | |
1935 | iov_iter_truncate(to, size); | |
1936 | return generic_file_read_iter(iocb, to); | |
1937 | } | |
1938 | EXPORT_SYMBOL_GPL(blkdev_read_iter); | |
1939 | ||
1940 | /* | |
1941 | * Try to release a page associated with block device when the system | |
1942 | * is under memory pressure. | |
1943 | */ | |
1944 | static int blkdev_releasepage(struct page *page, gfp_t wait) | |
1945 | { | |
1946 | struct super_block *super = BDEV_I(page->mapping->host)->bdev.bd_super; | |
1947 | ||
1948 | if (super && super->s_op->bdev_try_to_free_page) | |
1949 | return super->s_op->bdev_try_to_free_page(super, page, wait); | |
1950 | ||
1951 | return try_to_free_buffers(page); | |
1952 | } | |
1953 | ||
1954 | static int blkdev_writepages(struct address_space *mapping, | |
1955 | struct writeback_control *wbc) | |
1956 | { | |
1957 | if (dax_mapping(mapping)) { | |
1958 | struct block_device *bdev = I_BDEV(mapping->host); | |
1959 | ||
1960 | return dax_writeback_mapping_range(mapping, bdev, wbc); | |
1961 | } | |
1962 | return generic_writepages(mapping, wbc); | |
1963 | } | |
1964 | ||
1965 | static const struct address_space_operations def_blk_aops = { | |
1966 | .readpage = blkdev_readpage, | |
1967 | .readpages = blkdev_readpages, | |
1968 | .writepage = blkdev_writepage, | |
1969 | .write_begin = blkdev_write_begin, | |
1970 | .write_end = blkdev_write_end, | |
1971 | .writepages = blkdev_writepages, | |
1972 | .releasepage = blkdev_releasepage, | |
1973 | .direct_IO = blkdev_direct_IO, | |
1974 | .is_dirty_writeback = buffer_check_dirty_writeback, | |
1975 | }; | |
1976 | ||
1977 | #define BLKDEV_FALLOC_FL_SUPPORTED \ | |
1978 | (FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | \ | |
1979 | FALLOC_FL_ZERO_RANGE | FALLOC_FL_NO_HIDE_STALE) | |
1980 | ||
1981 | static long blkdev_fallocate(struct file *file, int mode, loff_t start, | |
1982 | loff_t len) | |
1983 | { | |
1984 | struct block_device *bdev = I_BDEV(bdev_file_inode(file)); | |
1985 | struct address_space *mapping; | |
1986 | loff_t end = start + len - 1; | |
1987 | loff_t isize; | |
1988 | int error; | |
1989 | ||
1990 | /* Fail if we don't recognize the flags. */ | |
1991 | if (mode & ~BLKDEV_FALLOC_FL_SUPPORTED) | |
1992 | return -EOPNOTSUPP; | |
1993 | ||
1994 | /* Don't go off the end of the device. */ | |
1995 | isize = i_size_read(bdev->bd_inode); | |
1996 | if (start >= isize) | |
1997 | return -EINVAL; | |
1998 | if (end >= isize) { | |
1999 | if (mode & FALLOC_FL_KEEP_SIZE) { | |
2000 | len = isize - start; | |
2001 | end = start + len - 1; | |
2002 | } else | |
2003 | return -EINVAL; | |
2004 | } | |
2005 | ||
2006 | /* | |
2007 | * Don't allow IO that isn't aligned to logical block size. | |
2008 | */ | |
2009 | if ((start | len) & (bdev_logical_block_size(bdev) - 1)) | |
2010 | return -EINVAL; | |
2011 | ||
2012 | /* Invalidate the page cache, including dirty pages. */ | |
2013 | mapping = bdev->bd_inode->i_mapping; | |
2014 | truncate_inode_pages_range(mapping, start, end); | |
2015 | ||
2016 | switch (mode) { | |
2017 | case FALLOC_FL_ZERO_RANGE: | |
2018 | case FALLOC_FL_ZERO_RANGE | FALLOC_FL_KEEP_SIZE: | |
2019 | error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, | |
2020 | GFP_KERNEL, BLKDEV_ZERO_NOUNMAP); | |
2021 | break; | |
2022 | case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE: | |
2023 | error = blkdev_issue_zeroout(bdev, start >> 9, len >> 9, | |
2024 | GFP_KERNEL, BLKDEV_ZERO_NOFALLBACK); | |
2025 | break; | |
2026 | case FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE | FALLOC_FL_NO_HIDE_STALE: | |
2027 | error = blkdev_issue_discard(bdev, start >> 9, len >> 9, | |
2028 | GFP_KERNEL, 0); | |
2029 | break; | |
2030 | default: | |
2031 | return -EOPNOTSUPP; | |
2032 | } | |
2033 | if (error) | |
2034 | return error; | |
2035 | ||
2036 | /* | |
2037 | * Invalidate again; if someone wandered in and dirtied a page, | |
2038 | * the caller will be given -EBUSY. The third argument is | |
2039 | * inclusive, so the rounding here is safe. | |
2040 | */ | |
2041 | return invalidate_inode_pages2_range(mapping, | |
2042 | start >> PAGE_SHIFT, | |
2043 | end >> PAGE_SHIFT); | |
2044 | } | |
2045 | ||
2046 | const struct file_operations def_blk_fops = { | |
2047 | .open = blkdev_open, | |
2048 | .release = blkdev_close, | |
2049 | .llseek = block_llseek, | |
2050 | .read_iter = blkdev_read_iter, | |
2051 | .write_iter = blkdev_write_iter, | |
2052 | .mmap = generic_file_mmap, | |
2053 | .fsync = blkdev_fsync, | |
2054 | .unlocked_ioctl = block_ioctl, | |
2055 | #ifdef CONFIG_COMPAT | |
2056 | .compat_ioctl = compat_blkdev_ioctl, | |
2057 | #endif | |
2058 | .splice_read = generic_file_splice_read, | |
2059 | .splice_write = iter_file_splice_write, | |
2060 | .fallocate = blkdev_fallocate, | |
2061 | }; | |
2062 | ||
2063 | int ioctl_by_bdev(struct block_device *bdev, unsigned cmd, unsigned long arg) | |
2064 | { | |
2065 | int res; | |
2066 | mm_segment_t old_fs = get_fs(); | |
2067 | set_fs(KERNEL_DS); | |
2068 | res = blkdev_ioctl(bdev, 0, cmd, arg); | |
2069 | set_fs(old_fs); | |
2070 | return res; | |
2071 | } | |
2072 | ||
2073 | EXPORT_SYMBOL(ioctl_by_bdev); | |
2074 | ||
2075 | /** | |
2076 | * lookup_bdev - lookup a struct block_device by name | |
2077 | * @pathname: special file representing the block device | |
2078 | * @mask: rights to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC) | |
2079 | * | |
2080 | * Get a reference to the blockdevice at @pathname in the current | |
2081 | * namespace if possible and return it. Return ERR_PTR(error) | |
2082 | * otherwise. If @mask is non-zero, check for access rights to the | |
2083 | * inode at @pathname. | |
2084 | */ | |
2085 | struct block_device *lookup_bdev(const char *pathname, int mask) | |
2086 | { | |
2087 | struct block_device *bdev; | |
2088 | struct inode *inode; | |
2089 | struct path path; | |
2090 | int error; | |
2091 | ||
2092 | if (!pathname || !*pathname) | |
2093 | return ERR_PTR(-EINVAL); | |
2094 | ||
2095 | error = kern_path(pathname, LOOKUP_FOLLOW, &path); | |
2096 | if (error) | |
2097 | return ERR_PTR(error); | |
2098 | ||
2099 | inode = d_backing_inode(path.dentry); | |
2100 | if (mask != 0 && !capable(CAP_SYS_ADMIN)) { | |
2101 | error = __inode_permission(inode, mask); | |
2102 | if (error) | |
2103 | goto fail; | |
2104 | } | |
2105 | error = -ENOTBLK; | |
2106 | if (!S_ISBLK(inode->i_mode)) | |
2107 | goto fail; | |
2108 | error = -EACCES; | |
2109 | if (!may_open_dev(&path)) | |
2110 | goto fail; | |
2111 | error = -ENOMEM; | |
2112 | bdev = bd_acquire(inode); | |
2113 | if (!bdev) | |
2114 | goto fail; | |
2115 | out: | |
2116 | path_put(&path); | |
2117 | return bdev; | |
2118 | fail: | |
2119 | bdev = ERR_PTR(error); | |
2120 | goto out; | |
2121 | } | |
2122 | EXPORT_SYMBOL(lookup_bdev); | |
2123 | ||
2124 | int __invalidate_device(struct block_device *bdev, bool kill_dirty) | |
2125 | { | |
2126 | struct super_block *sb = get_super(bdev); | |
2127 | int res = 0; | |
2128 | ||
2129 | if (sb) { | |
2130 | /* | |
2131 | * no need to lock the super, get_super holds the | |
2132 | * read mutex so the filesystem cannot go away | |
2133 | * under us (->put_super runs with the write lock | |
2134 | * hold). | |
2135 | */ | |
2136 | shrink_dcache_sb(sb); | |
2137 | res = invalidate_inodes(sb, kill_dirty); | |
2138 | drop_super(sb); | |
2139 | } | |
2140 | invalidate_bdev(bdev); | |
2141 | return res; | |
2142 | } | |
2143 | EXPORT_SYMBOL(__invalidate_device); | |
2144 | ||
2145 | void iterate_bdevs(void (*func)(struct block_device *, void *), void *arg) | |
2146 | { | |
2147 | struct inode *inode, *old_inode = NULL; | |
2148 | ||
2149 | spin_lock(&blockdev_superblock->s_inode_list_lock); | |
2150 | list_for_each_entry(inode, &blockdev_superblock->s_inodes, i_sb_list) { | |
2151 | struct address_space *mapping = inode->i_mapping; | |
2152 | struct block_device *bdev; | |
2153 | ||
2154 | spin_lock(&inode->i_lock); | |
2155 | if (inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW) || | |
2156 | mapping->nrpages == 0) { | |
2157 | spin_unlock(&inode->i_lock); | |
2158 | continue; | |
2159 | } | |
2160 | __iget(inode); | |
2161 | spin_unlock(&inode->i_lock); | |
2162 | spin_unlock(&blockdev_superblock->s_inode_list_lock); | |
2163 | /* | |
2164 | * We hold a reference to 'inode' so it couldn't have been | |
2165 | * removed from s_inodes list while we dropped the | |
2166 | * s_inode_list_lock We cannot iput the inode now as we can | |
2167 | * be holding the last reference and we cannot iput it under | |
2168 | * s_inode_list_lock. So we keep the reference and iput it | |
2169 | * later. | |
2170 | */ | |
2171 | iput(old_inode); | |
2172 | old_inode = inode; | |
2173 | bdev = I_BDEV(inode); | |
2174 | ||
2175 | mutex_lock(&bdev->bd_mutex); | |
2176 | if (bdev->bd_openers) | |
2177 | func(bdev, arg); | |
2178 | mutex_unlock(&bdev->bd_mutex); | |
2179 | ||
2180 | spin_lock(&blockdev_superblock->s_inode_list_lock); | |
2181 | } | |
2182 | spin_unlock(&blockdev_superblock->s_inode_list_lock); | |
2183 | iput(old_inode); | |
2184 | } |