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1da177e4 LT |
1 | /* |
2 | * fs/direct-io.c | |
3 | * | |
4 | * Copyright (C) 2002, Linus Torvalds. | |
5 | * | |
6 | * O_DIRECT | |
7 | * | |
e1f8e874 | 8 | * 04Jul2002 Andrew Morton |
1da177e4 LT |
9 | * Initial version |
10 | * 11Sep2002 janetinc@us.ibm.com | |
11 | * added readv/writev support. | |
e1f8e874 | 12 | * 29Oct2002 Andrew Morton |
1da177e4 LT |
13 | * rewrote bio_add_page() support. |
14 | * 30Oct2002 pbadari@us.ibm.com | |
15 | * added support for non-aligned IO. | |
16 | * 06Nov2002 pbadari@us.ibm.com | |
17 | * added asynchronous IO support. | |
18 | * 21Jul2003 nathans@sgi.com | |
19 | * added IO completion notifier. | |
20 | */ | |
21 | ||
22 | #include <linux/kernel.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/types.h> | |
25 | #include <linux/fs.h> | |
26 | #include <linux/mm.h> | |
27 | #include <linux/slab.h> | |
28 | #include <linux/highmem.h> | |
29 | #include <linux/pagemap.h> | |
98c4d57d | 30 | #include <linux/task_io_accounting_ops.h> |
1da177e4 LT |
31 | #include <linux/bio.h> |
32 | #include <linux/wait.h> | |
33 | #include <linux/err.h> | |
34 | #include <linux/blkdev.h> | |
35 | #include <linux/buffer_head.h> | |
36 | #include <linux/rwsem.h> | |
37 | #include <linux/uio.h> | |
60063497 | 38 | #include <linux/atomic.h> |
65dd2aa9 | 39 | #include <linux/prefetch.h> |
1da177e4 LT |
40 | |
41 | /* | |
42 | * How many user pages to map in one call to get_user_pages(). This determines | |
cde1ecb3 | 43 | * the size of a structure in the slab cache |
1da177e4 LT |
44 | */ |
45 | #define DIO_PAGES 64 | |
46 | ||
47 | /* | |
48 | * This code generally works in units of "dio_blocks". A dio_block is | |
49 | * somewhere between the hard sector size and the filesystem block size. it | |
50 | * is determined on a per-invocation basis. When talking to the filesystem | |
51 | * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity | |
52 | * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted | |
53 | * to bio_block quantities by shifting left by blkfactor. | |
54 | * | |
55 | * If blkfactor is zero then the user's request was aligned to the filesystem's | |
56 | * blocksize. | |
1da177e4 LT |
57 | */ |
58 | ||
eb28be2b AK |
59 | /* dio_state only used in the submission path */ |
60 | ||
61 | struct dio_submit { | |
1da177e4 | 62 | struct bio *bio; /* bio under assembly */ |
1da177e4 LT |
63 | unsigned blkbits; /* doesn't change */ |
64 | unsigned blkfactor; /* When we're using an alignment which | |
65 | is finer than the filesystem's soft | |
66 | blocksize, this specifies how much | |
67 | finer. blkfactor=2 means 1/4-block | |
68 | alignment. Does not change */ | |
69 | unsigned start_zero_done; /* flag: sub-blocksize zeroing has | |
70 | been performed at the start of a | |
71 | write */ | |
72 | int pages_in_io; /* approximate total IO pages */ | |
1da177e4 LT |
73 | sector_t block_in_file; /* Current offset into the underlying |
74 | file in dio_block units. */ | |
75 | unsigned blocks_available; /* At block_in_file. changes */ | |
0dc2bc49 | 76 | int reap_counter; /* rate limit reaping */ |
1da177e4 | 77 | sector_t final_block_in_request;/* doesn't change */ |
1da177e4 | 78 | int boundary; /* prev block is at a boundary */ |
1d8fa7a2 | 79 | get_block_t *get_block; /* block mapping function */ |
facd07b0 | 80 | dio_submit_t *submit_io; /* IO submition function */ |
eb28be2b | 81 | |
facd07b0 | 82 | loff_t logical_offset_in_bio; /* current first logical block in bio */ |
1da177e4 LT |
83 | sector_t final_block_in_bio; /* current final block in bio + 1 */ |
84 | sector_t next_block_for_io; /* next block to be put under IO, | |
85 | in dio_blocks units */ | |
1da177e4 LT |
86 | |
87 | /* | |
88 | * Deferred addition of a page to the dio. These variables are | |
89 | * private to dio_send_cur_page(), submit_page_section() and | |
90 | * dio_bio_add_page(). | |
91 | */ | |
92 | struct page *cur_page; /* The page */ | |
93 | unsigned cur_page_offset; /* Offset into it, in bytes */ | |
94 | unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ | |
95 | sector_t cur_page_block; /* Where it starts */ | |
facd07b0 | 96 | loff_t cur_page_fs_offset; /* Offset in file */ |
1da177e4 | 97 | |
7b2c99d1 | 98 | struct iov_iter *iter; |
1da177e4 LT |
99 | /* |
100 | * Page queue. These variables belong to dio_refill_pages() and | |
101 | * dio_get_page(). | |
102 | */ | |
1da177e4 LT |
103 | unsigned head; /* next page to process */ |
104 | unsigned tail; /* last valid page + 1 */ | |
7b2c99d1 | 105 | size_t from, to; |
eb28be2b AK |
106 | }; |
107 | ||
108 | /* dio_state communicated between submission path and end_io */ | |
109 | struct dio { | |
110 | int flags; /* doesn't change */ | |
eb28be2b | 111 | int rw; |
0dc2bc49 | 112 | struct inode *inode; |
eb28be2b AK |
113 | loff_t i_size; /* i_size when submitted */ |
114 | dio_iodone_t *end_io; /* IO completion function */ | |
eb28be2b | 115 | |
18772641 | 116 | void *private; /* copy from map_bh.b_private */ |
eb28be2b AK |
117 | |
118 | /* BIO completion state */ | |
119 | spinlock_t bio_lock; /* protects BIO fields below */ | |
0dc2bc49 AK |
120 | int page_errors; /* errno from get_user_pages() */ |
121 | int is_async; /* is IO async ? */ | |
7b7a8665 | 122 | bool defer_completion; /* defer AIO completion to workqueue? */ |
53cbf3b1 | 123 | bool should_dirty; /* if pages should be dirtied */ |
0dc2bc49 | 124 | int io_error; /* IO error in completion path */ |
eb28be2b AK |
125 | unsigned long refcount; /* direct_io_worker() and bios */ |
126 | struct bio *bio_list; /* singly linked via bi_private */ | |
127 | struct task_struct *waiter; /* waiting task (NULL if none) */ | |
128 | ||
129 | /* AIO related stuff */ | |
130 | struct kiocb *iocb; /* kiocb */ | |
eb28be2b AK |
131 | ssize_t result; /* IO result */ |
132 | ||
23aee091 JM |
133 | /* |
134 | * pages[] (and any fields placed after it) are not zeroed out at | |
135 | * allocation time. Don't add new fields after pages[] unless you | |
136 | * wish that they not be zeroed. | |
137 | */ | |
7b7a8665 CH |
138 | union { |
139 | struct page *pages[DIO_PAGES]; /* page buffer */ | |
140 | struct work_struct complete_work;/* deferred AIO completion */ | |
141 | }; | |
6e8267f5 AK |
142 | } ____cacheline_aligned_in_smp; |
143 | ||
144 | static struct kmem_cache *dio_cache __read_mostly; | |
1da177e4 LT |
145 | |
146 | /* | |
147 | * How many pages are in the queue? | |
148 | */ | |
eb28be2b | 149 | static inline unsigned dio_pages_present(struct dio_submit *sdio) |
1da177e4 | 150 | { |
eb28be2b | 151 | return sdio->tail - sdio->head; |
1da177e4 LT |
152 | } |
153 | ||
154 | /* | |
155 | * Go grab and pin some userspace pages. Typically we'll get 64 at a time. | |
156 | */ | |
ba253fbf | 157 | static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 158 | { |
7b2c99d1 | 159 | ssize_t ret; |
1da177e4 | 160 | |
2c80929c | 161 | ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES, |
7b2c99d1 | 162 | &sdio->from); |
1da177e4 | 163 | |
eb28be2b | 164 | if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) { |
557ed1fa | 165 | struct page *page = ZERO_PAGE(0); |
1da177e4 LT |
166 | /* |
167 | * A memory fault, but the filesystem has some outstanding | |
168 | * mapped blocks. We need to use those blocks up to avoid | |
169 | * leaking stale data in the file. | |
170 | */ | |
171 | if (dio->page_errors == 0) | |
172 | dio->page_errors = ret; | |
b5810039 NP |
173 | page_cache_get(page); |
174 | dio->pages[0] = page; | |
eb28be2b AK |
175 | sdio->head = 0; |
176 | sdio->tail = 1; | |
7b2c99d1 AV |
177 | sdio->from = 0; |
178 | sdio->to = PAGE_SIZE; | |
179 | return 0; | |
1da177e4 LT |
180 | } |
181 | ||
182 | if (ret >= 0) { | |
7b2c99d1 AV |
183 | iov_iter_advance(sdio->iter, ret); |
184 | ret += sdio->from; | |
eb28be2b | 185 | sdio->head = 0; |
7b2c99d1 AV |
186 | sdio->tail = (ret + PAGE_SIZE - 1) / PAGE_SIZE; |
187 | sdio->to = ((ret - 1) & (PAGE_SIZE - 1)) + 1; | |
188 | return 0; | |
1da177e4 | 189 | } |
1da177e4 LT |
190 | return ret; |
191 | } | |
192 | ||
193 | /* | |
194 | * Get another userspace page. Returns an ERR_PTR on error. Pages are | |
195 | * buffered inside the dio so that we can call get_user_pages() against a | |
196 | * decent number of pages, less frequently. To provide nicer use of the | |
197 | * L1 cache. | |
198 | */ | |
ba253fbf | 199 | static inline struct page *dio_get_page(struct dio *dio, |
6fcc5420 | 200 | struct dio_submit *sdio) |
1da177e4 | 201 | { |
eb28be2b | 202 | if (dio_pages_present(sdio) == 0) { |
1da177e4 LT |
203 | int ret; |
204 | ||
eb28be2b | 205 | ret = dio_refill_pages(dio, sdio); |
1da177e4 LT |
206 | if (ret) |
207 | return ERR_PTR(ret); | |
eb28be2b | 208 | BUG_ON(dio_pages_present(sdio) == 0); |
1da177e4 | 209 | } |
6fcc5420 | 210 | return dio->pages[sdio->head]; |
1da177e4 LT |
211 | } |
212 | ||
6d544bb4 ZB |
213 | /** |
214 | * dio_complete() - called when all DIO BIO I/O has been completed | |
215 | * @offset: the byte offset in the file of the completed operation | |
216 | * | |
7b7a8665 CH |
217 | * This drops i_dio_count, lets interested parties know that a DIO operation |
218 | * has completed, and calculates the resulting return code for the operation. | |
6d544bb4 ZB |
219 | * |
220 | * It lets the filesystem know if it registered an interest earlier via | |
221 | * get_block. Pass the private field of the map buffer_head so that | |
222 | * filesystems can use it to hold additional state between get_block calls and | |
223 | * dio_complete. | |
1da177e4 | 224 | */ |
7b7a8665 CH |
225 | static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, |
226 | bool is_async) | |
1da177e4 | 227 | { |
6d544bb4 ZB |
228 | ssize_t transferred = 0; |
229 | ||
8459d86a ZB |
230 | /* |
231 | * AIO submission can race with bio completion to get here while | |
232 | * expecting to have the last io completed by bio completion. | |
233 | * In that case -EIOCBQUEUED is in fact not an error we want | |
234 | * to preserve through this call. | |
235 | */ | |
236 | if (ret == -EIOCBQUEUED) | |
237 | ret = 0; | |
238 | ||
6d544bb4 ZB |
239 | if (dio->result) { |
240 | transferred = dio->result; | |
241 | ||
242 | /* Check for short read case */ | |
243 | if ((dio->rw == READ) && ((offset + transferred) > dio->i_size)) | |
244 | transferred = dio->i_size - offset; | |
245 | } | |
246 | ||
6d544bb4 ZB |
247 | if (ret == 0) |
248 | ret = dio->page_errors; | |
249 | if (ret == 0) | |
250 | ret = dio->io_error; | |
251 | if (ret == 0) | |
252 | ret = transferred; | |
253 | ||
7b7a8665 CH |
254 | if (dio->end_io && dio->result) |
255 | dio->end_io(dio->iocb, offset, transferred, dio->private); | |
256 | ||
fe0f07d0 JA |
257 | if (!(dio->flags & DIO_SKIP_DIO_COUNT)) |
258 | inode_dio_end(dio->inode); | |
259 | ||
02afc27f CH |
260 | if (is_async) { |
261 | if (dio->rw & WRITE) { | |
262 | int err; | |
263 | ||
264 | err = generic_write_sync(dio->iocb->ki_filp, offset, | |
265 | transferred); | |
266 | if (err < 0 && ret > 0) | |
267 | ret = err; | |
268 | } | |
269 | ||
04b2fa9f | 270 | dio->iocb->ki_complete(dio->iocb, ret, 0); |
02afc27f | 271 | } |
40e2e973 | 272 | |
7b7a8665 | 273 | kmem_cache_free(dio_cache, dio); |
6d544bb4 | 274 | return ret; |
1da177e4 LT |
275 | } |
276 | ||
7b7a8665 CH |
277 | static void dio_aio_complete_work(struct work_struct *work) |
278 | { | |
279 | struct dio *dio = container_of(work, struct dio, complete_work); | |
280 | ||
281 | dio_complete(dio, dio->iocb->ki_pos, 0, true); | |
282 | } | |
283 | ||
1da177e4 | 284 | static int dio_bio_complete(struct dio *dio, struct bio *bio); |
7b7a8665 | 285 | |
1da177e4 LT |
286 | /* |
287 | * Asynchronous IO callback. | |
288 | */ | |
4246a0b6 | 289 | static void dio_bio_end_aio(struct bio *bio) |
1da177e4 LT |
290 | { |
291 | struct dio *dio = bio->bi_private; | |
5eb6c7a2 ZB |
292 | unsigned long remaining; |
293 | unsigned long flags; | |
1da177e4 | 294 | |
1da177e4 LT |
295 | /* cleanup the bio */ |
296 | dio_bio_complete(dio, bio); | |
0273201e | 297 | |
5eb6c7a2 ZB |
298 | spin_lock_irqsave(&dio->bio_lock, flags); |
299 | remaining = --dio->refcount; | |
300 | if (remaining == 1 && dio->waiter) | |
20258b2b | 301 | wake_up_process(dio->waiter); |
5eb6c7a2 | 302 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
20258b2b | 303 | |
8459d86a | 304 | if (remaining == 0) { |
7b7a8665 CH |
305 | if (dio->result && dio->defer_completion) { |
306 | INIT_WORK(&dio->complete_work, dio_aio_complete_work); | |
307 | queue_work(dio->inode->i_sb->s_dio_done_wq, | |
308 | &dio->complete_work); | |
309 | } else { | |
310 | dio_complete(dio, dio->iocb->ki_pos, 0, true); | |
311 | } | |
8459d86a | 312 | } |
1da177e4 LT |
313 | } |
314 | ||
315 | /* | |
316 | * The BIO completion handler simply queues the BIO up for the process-context | |
317 | * handler. | |
318 | * | |
319 | * During I/O bi_private points at the dio. After I/O, bi_private is used to | |
320 | * implement a singly-linked list of completed BIOs, at dio->bio_list. | |
321 | */ | |
4246a0b6 | 322 | static void dio_bio_end_io(struct bio *bio) |
1da177e4 LT |
323 | { |
324 | struct dio *dio = bio->bi_private; | |
325 | unsigned long flags; | |
326 | ||
1da177e4 LT |
327 | spin_lock_irqsave(&dio->bio_lock, flags); |
328 | bio->bi_private = dio->bio_list; | |
329 | dio->bio_list = bio; | |
5eb6c7a2 | 330 | if (--dio->refcount == 1 && dio->waiter) |
1da177e4 LT |
331 | wake_up_process(dio->waiter); |
332 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
1da177e4 LT |
333 | } |
334 | ||
facd07b0 JB |
335 | /** |
336 | * dio_end_io - handle the end io action for the given bio | |
337 | * @bio: The direct io bio thats being completed | |
338 | * @error: Error if there was one | |
339 | * | |
340 | * This is meant to be called by any filesystem that uses their own dio_submit_t | |
341 | * so that the DIO specific endio actions are dealt with after the filesystem | |
342 | * has done it's completion work. | |
343 | */ | |
344 | void dio_end_io(struct bio *bio, int error) | |
345 | { | |
346 | struct dio *dio = bio->bi_private; | |
347 | ||
348 | if (dio->is_async) | |
4246a0b6 | 349 | dio_bio_end_aio(bio); |
facd07b0 | 350 | else |
4246a0b6 | 351 | dio_bio_end_io(bio); |
facd07b0 JB |
352 | } |
353 | EXPORT_SYMBOL_GPL(dio_end_io); | |
354 | ||
ba253fbf | 355 | static inline void |
eb28be2b AK |
356 | dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, |
357 | struct block_device *bdev, | |
358 | sector_t first_sector, int nr_vecs) | |
1da177e4 LT |
359 | { |
360 | struct bio *bio; | |
361 | ||
20d9600c DD |
362 | /* |
363 | * bio_alloc() is guaranteed to return a bio when called with | |
364 | * __GFP_WAIT and we request a valid number of vectors. | |
365 | */ | |
1da177e4 | 366 | bio = bio_alloc(GFP_KERNEL, nr_vecs); |
1da177e4 LT |
367 | |
368 | bio->bi_bdev = bdev; | |
4f024f37 | 369 | bio->bi_iter.bi_sector = first_sector; |
1da177e4 LT |
370 | if (dio->is_async) |
371 | bio->bi_end_io = dio_bio_end_aio; | |
372 | else | |
373 | bio->bi_end_io = dio_bio_end_io; | |
374 | ||
eb28be2b AK |
375 | sdio->bio = bio; |
376 | sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; | |
1da177e4 LT |
377 | } |
378 | ||
379 | /* | |
380 | * In the AIO read case we speculatively dirty the pages before starting IO. | |
381 | * During IO completion, any of these pages which happen to have been written | |
382 | * back will be redirtied by bio_check_pages_dirty(). | |
0273201e ZB |
383 | * |
384 | * bios hold a dio reference between submit_bio and ->end_io. | |
1da177e4 | 385 | */ |
ba253fbf | 386 | static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 387 | { |
eb28be2b | 388 | struct bio *bio = sdio->bio; |
5eb6c7a2 | 389 | unsigned long flags; |
1da177e4 LT |
390 | |
391 | bio->bi_private = dio; | |
5eb6c7a2 ZB |
392 | |
393 | spin_lock_irqsave(&dio->bio_lock, flags); | |
394 | dio->refcount++; | |
395 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
396 | ||
53cbf3b1 | 397 | if (dio->is_async && dio->rw == READ && dio->should_dirty) |
1da177e4 | 398 | bio_set_pages_dirty(bio); |
5eb6c7a2 | 399 | |
eb28be2b AK |
400 | if (sdio->submit_io) |
401 | sdio->submit_io(dio->rw, bio, dio->inode, | |
402 | sdio->logical_offset_in_bio); | |
facd07b0 JB |
403 | else |
404 | submit_bio(dio->rw, bio); | |
1da177e4 | 405 | |
eb28be2b AK |
406 | sdio->bio = NULL; |
407 | sdio->boundary = 0; | |
408 | sdio->logical_offset_in_bio = 0; | |
1da177e4 LT |
409 | } |
410 | ||
411 | /* | |
412 | * Release any resources in case of a failure | |
413 | */ | |
ba253fbf | 414 | static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 415 | { |
7b2c99d1 AV |
416 | while (sdio->head < sdio->tail) |
417 | page_cache_release(dio->pages[sdio->head++]); | |
1da177e4 LT |
418 | } |
419 | ||
420 | /* | |
0273201e ZB |
421 | * Wait for the next BIO to complete. Remove it and return it. NULL is |
422 | * returned once all BIOs have been completed. This must only be called once | |
423 | * all bios have been issued so that dio->refcount can only decrease. This | |
424 | * requires that that the caller hold a reference on the dio. | |
1da177e4 LT |
425 | */ |
426 | static struct bio *dio_await_one(struct dio *dio) | |
427 | { | |
428 | unsigned long flags; | |
0273201e | 429 | struct bio *bio = NULL; |
1da177e4 LT |
430 | |
431 | spin_lock_irqsave(&dio->bio_lock, flags); | |
5eb6c7a2 ZB |
432 | |
433 | /* | |
434 | * Wait as long as the list is empty and there are bios in flight. bio | |
435 | * completion drops the count, maybe adds to the list, and wakes while | |
436 | * holding the bio_lock so we don't need set_current_state()'s barrier | |
437 | * and can call it after testing our condition. | |
438 | */ | |
439 | while (dio->refcount > 1 && dio->bio_list == NULL) { | |
440 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
441 | dio->waiter = current; | |
442 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
443 | io_schedule(); | |
444 | /* wake up sets us TASK_RUNNING */ | |
445 | spin_lock_irqsave(&dio->bio_lock, flags); | |
446 | dio->waiter = NULL; | |
1da177e4 | 447 | } |
0273201e ZB |
448 | if (dio->bio_list) { |
449 | bio = dio->bio_list; | |
450 | dio->bio_list = bio->bi_private; | |
451 | } | |
1da177e4 LT |
452 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
453 | return bio; | |
454 | } | |
455 | ||
456 | /* | |
457 | * Process one completed BIO. No locks are held. | |
458 | */ | |
459 | static int dio_bio_complete(struct dio *dio, struct bio *bio) | |
460 | { | |
cb34e057 KO |
461 | struct bio_vec *bvec; |
462 | unsigned i; | |
9b81c842 | 463 | int err; |
1da177e4 | 464 | |
4246a0b6 | 465 | if (bio->bi_error) |
174e27c6 | 466 | dio->io_error = -EIO; |
1da177e4 | 467 | |
53cbf3b1 | 468 | if (dio->is_async && dio->rw == READ && dio->should_dirty) { |
1da177e4 | 469 | bio_check_pages_dirty(bio); /* transfers ownership */ |
9b81c842 | 470 | err = bio->bi_error; |
1da177e4 | 471 | } else { |
cb34e057 KO |
472 | bio_for_each_segment_all(bvec, bio, i) { |
473 | struct page *page = bvec->bv_page; | |
1da177e4 | 474 | |
53cbf3b1 ML |
475 | if (dio->rw == READ && !PageCompound(page) && |
476 | dio->should_dirty) | |
1da177e4 LT |
477 | set_page_dirty_lock(page); |
478 | page_cache_release(page); | |
479 | } | |
9b81c842 | 480 | err = bio->bi_error; |
1da177e4 LT |
481 | bio_put(bio); |
482 | } | |
9b81c842 | 483 | return err; |
1da177e4 LT |
484 | } |
485 | ||
486 | /* | |
0273201e ZB |
487 | * Wait on and process all in-flight BIOs. This must only be called once |
488 | * all bios have been issued so that the refcount can only decrease. | |
489 | * This just waits for all bios to make it through dio_bio_complete. IO | |
beb7dd86 | 490 | * errors are propagated through dio->io_error and should be propagated via |
0273201e | 491 | * dio_complete(). |
1da177e4 | 492 | */ |
6d544bb4 | 493 | static void dio_await_completion(struct dio *dio) |
1da177e4 | 494 | { |
0273201e ZB |
495 | struct bio *bio; |
496 | do { | |
497 | bio = dio_await_one(dio); | |
498 | if (bio) | |
499 | dio_bio_complete(dio, bio); | |
500 | } while (bio); | |
1da177e4 LT |
501 | } |
502 | ||
503 | /* | |
504 | * A really large O_DIRECT read or write can generate a lot of BIOs. So | |
505 | * to keep the memory consumption sane we periodically reap any completed BIOs | |
506 | * during the BIO generation phase. | |
507 | * | |
508 | * This also helps to limit the peak amount of pinned userspace memory. | |
509 | */ | |
ba253fbf | 510 | static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
511 | { |
512 | int ret = 0; | |
513 | ||
eb28be2b | 514 | if (sdio->reap_counter++ >= 64) { |
1da177e4 LT |
515 | while (dio->bio_list) { |
516 | unsigned long flags; | |
517 | struct bio *bio; | |
518 | int ret2; | |
519 | ||
520 | spin_lock_irqsave(&dio->bio_lock, flags); | |
521 | bio = dio->bio_list; | |
522 | dio->bio_list = bio->bi_private; | |
523 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
524 | ret2 = dio_bio_complete(dio, bio); | |
525 | if (ret == 0) | |
526 | ret = ret2; | |
527 | } | |
eb28be2b | 528 | sdio->reap_counter = 0; |
1da177e4 LT |
529 | } |
530 | return ret; | |
531 | } | |
532 | ||
7b7a8665 CH |
533 | /* |
534 | * Create workqueue for deferred direct IO completions. We allocate the | |
535 | * workqueue when it's first needed. This avoids creating workqueue for | |
536 | * filesystems that don't need it and also allows us to create the workqueue | |
537 | * late enough so the we can include s_id in the name of the workqueue. | |
538 | */ | |
539 | static int sb_init_dio_done_wq(struct super_block *sb) | |
540 | { | |
45150c43 | 541 | struct workqueue_struct *old; |
7b7a8665 CH |
542 | struct workqueue_struct *wq = alloc_workqueue("dio/%s", |
543 | WQ_MEM_RECLAIM, 0, | |
544 | sb->s_id); | |
545 | if (!wq) | |
546 | return -ENOMEM; | |
547 | /* | |
548 | * This has to be atomic as more DIOs can race to create the workqueue | |
549 | */ | |
45150c43 | 550 | old = cmpxchg(&sb->s_dio_done_wq, NULL, wq); |
7b7a8665 | 551 | /* Someone created workqueue before us? Free ours... */ |
45150c43 | 552 | if (old) |
7b7a8665 CH |
553 | destroy_workqueue(wq); |
554 | return 0; | |
555 | } | |
556 | ||
557 | static int dio_set_defer_completion(struct dio *dio) | |
558 | { | |
559 | struct super_block *sb = dio->inode->i_sb; | |
560 | ||
561 | if (dio->defer_completion) | |
562 | return 0; | |
563 | dio->defer_completion = true; | |
564 | if (!sb->s_dio_done_wq) | |
565 | return sb_init_dio_done_wq(sb); | |
566 | return 0; | |
567 | } | |
568 | ||
1da177e4 LT |
569 | /* |
570 | * Call into the fs to map some more disk blocks. We record the current number | |
eb28be2b | 571 | * of available blocks at sdio->blocks_available. These are in units of the |
1da177e4 LT |
572 | * fs blocksize, (1 << inode->i_blkbits). |
573 | * | |
574 | * The fs is allowed to map lots of blocks at once. If it wants to do that, | |
575 | * it uses the passed inode-relative block number as the file offset, as usual. | |
576 | * | |
1d8fa7a2 | 577 | * get_block() is passed the number of i_blkbits-sized blocks which direct_io |
1da177e4 LT |
578 | * has remaining to do. The fs should not map more than this number of blocks. |
579 | * | |
580 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to | |
581 | * indicate how much contiguous disk space has been made available at | |
582 | * bh->b_blocknr. | |
583 | * | |
584 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). | |
585 | * This isn't very efficient... | |
586 | * | |
587 | * In the case of filesystem holes: the fs may return an arbitrarily-large | |
588 | * hole by returning an appropriate value in b_size and by clearing | |
589 | * buffer_mapped(). However the direct-io code will only process holes one | |
1d8fa7a2 | 590 | * block at a time - it will repeatedly call get_block() as it walks the hole. |
1da177e4 | 591 | */ |
18772641 AK |
592 | static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, |
593 | struct buffer_head *map_bh) | |
1da177e4 LT |
594 | { |
595 | int ret; | |
1da177e4 | 596 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ |
ae55e1aa | 597 | sector_t fs_endblk; /* Into file, in filesystem-sized blocks */ |
1da177e4 | 598 | unsigned long fs_count; /* Number of filesystem-sized blocks */ |
1da177e4 | 599 | int create; |
ab73857e | 600 | unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor; |
1da177e4 LT |
601 | |
602 | /* | |
603 | * If there was a memory error and we've overwritten all the | |
604 | * mapped blocks then we can now return that memory error | |
605 | */ | |
606 | ret = dio->page_errors; | |
607 | if (ret == 0) { | |
eb28be2b AK |
608 | BUG_ON(sdio->block_in_file >= sdio->final_block_in_request); |
609 | fs_startblk = sdio->block_in_file >> sdio->blkfactor; | |
ae55e1aa TM |
610 | fs_endblk = (sdio->final_block_in_request - 1) >> |
611 | sdio->blkfactor; | |
612 | fs_count = fs_endblk - fs_startblk + 1; | |
1da177e4 | 613 | |
3c674e74 | 614 | map_bh->b_state = 0; |
ab73857e | 615 | map_bh->b_size = fs_count << i_blkbits; |
3c674e74 | 616 | |
5fe878ae CH |
617 | /* |
618 | * For writes inside i_size on a DIO_SKIP_HOLES filesystem we | |
619 | * forbid block creations: only overwrites are permitted. | |
620 | * We will return early to the caller once we see an | |
621 | * unmapped buffer head returned, and the caller will fall | |
622 | * back to buffered I/O. | |
623 | * | |
624 | * Otherwise the decision is left to the get_blocks method, | |
625 | * which may decide to handle it or also return an unmapped | |
626 | * buffer head. | |
627 | */ | |
b31dc66a | 628 | create = dio->rw & WRITE; |
5fe878ae | 629 | if (dio->flags & DIO_SKIP_HOLES) { |
eb28be2b AK |
630 | if (sdio->block_in_file < (i_size_read(dio->inode) >> |
631 | sdio->blkbits)) | |
1da177e4 | 632 | create = 0; |
1da177e4 | 633 | } |
3c674e74 | 634 | |
eb28be2b | 635 | ret = (*sdio->get_block)(dio->inode, fs_startblk, |
1da177e4 | 636 | map_bh, create); |
18772641 AK |
637 | |
638 | /* Store for completion */ | |
639 | dio->private = map_bh->b_private; | |
7b7a8665 CH |
640 | |
641 | if (ret == 0 && buffer_defer_completion(map_bh)) | |
642 | ret = dio_set_defer_completion(dio); | |
1da177e4 LT |
643 | } |
644 | return ret; | |
645 | } | |
646 | ||
647 | /* | |
648 | * There is no bio. Make one now. | |
649 | */ | |
ba253fbf AK |
650 | static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio, |
651 | sector_t start_sector, struct buffer_head *map_bh) | |
1da177e4 LT |
652 | { |
653 | sector_t sector; | |
654 | int ret, nr_pages; | |
655 | ||
eb28be2b | 656 | ret = dio_bio_reap(dio, sdio); |
1da177e4 LT |
657 | if (ret) |
658 | goto out; | |
eb28be2b | 659 | sector = start_sector << (sdio->blkbits - 9); |
b54ffb73 | 660 | nr_pages = min(sdio->pages_in_io, BIO_MAX_PAGES); |
1da177e4 | 661 | BUG_ON(nr_pages <= 0); |
18772641 | 662 | dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages); |
eb28be2b | 663 | sdio->boundary = 0; |
1da177e4 LT |
664 | out: |
665 | return ret; | |
666 | } | |
667 | ||
668 | /* | |
669 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If | |
670 | * that was successful then update final_block_in_bio and take a ref against | |
671 | * the just-added page. | |
672 | * | |
673 | * Return zero on success. Non-zero means the caller needs to start a new BIO. | |
674 | */ | |
ba253fbf | 675 | static inline int dio_bio_add_page(struct dio_submit *sdio) |
1da177e4 LT |
676 | { |
677 | int ret; | |
678 | ||
eb28be2b AK |
679 | ret = bio_add_page(sdio->bio, sdio->cur_page, |
680 | sdio->cur_page_len, sdio->cur_page_offset); | |
681 | if (ret == sdio->cur_page_len) { | |
1da177e4 LT |
682 | /* |
683 | * Decrement count only, if we are done with this page | |
684 | */ | |
eb28be2b AK |
685 | if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE) |
686 | sdio->pages_in_io--; | |
687 | page_cache_get(sdio->cur_page); | |
688 | sdio->final_block_in_bio = sdio->cur_page_block + | |
689 | (sdio->cur_page_len >> sdio->blkbits); | |
1da177e4 LT |
690 | ret = 0; |
691 | } else { | |
692 | ret = 1; | |
693 | } | |
694 | return ret; | |
695 | } | |
696 | ||
697 | /* | |
698 | * Put cur_page under IO. The section of cur_page which is described by | |
699 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page | |
700 | * starts on-disk at cur_page_block. | |
701 | * | |
702 | * We take a ref against the page here (on behalf of its presence in the bio). | |
703 | * | |
704 | * The caller of this function is responsible for removing cur_page from the | |
705 | * dio, and for dropping the refcount which came from that presence. | |
706 | */ | |
ba253fbf AK |
707 | static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio, |
708 | struct buffer_head *map_bh) | |
1da177e4 LT |
709 | { |
710 | int ret = 0; | |
711 | ||
eb28be2b AK |
712 | if (sdio->bio) { |
713 | loff_t cur_offset = sdio->cur_page_fs_offset; | |
714 | loff_t bio_next_offset = sdio->logical_offset_in_bio + | |
4f024f37 | 715 | sdio->bio->bi_iter.bi_size; |
c2c6ca41 | 716 | |
1da177e4 | 717 | /* |
c2c6ca41 JB |
718 | * See whether this new request is contiguous with the old. |
719 | * | |
f0940cee NK |
720 | * Btrfs cannot handle having logically non-contiguous requests |
721 | * submitted. For example if you have | |
c2c6ca41 JB |
722 | * |
723 | * Logical: [0-4095][HOLE][8192-12287] | |
f0940cee | 724 | * Physical: [0-4095] [4096-8191] |
c2c6ca41 JB |
725 | * |
726 | * We cannot submit those pages together as one BIO. So if our | |
727 | * current logical offset in the file does not equal what would | |
728 | * be the next logical offset in the bio, submit the bio we | |
729 | * have. | |
1da177e4 | 730 | */ |
eb28be2b | 731 | if (sdio->final_block_in_bio != sdio->cur_page_block || |
c2c6ca41 | 732 | cur_offset != bio_next_offset) |
eb28be2b | 733 | dio_bio_submit(dio, sdio); |
1da177e4 LT |
734 | } |
735 | ||
eb28be2b | 736 | if (sdio->bio == NULL) { |
18772641 | 737 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 LT |
738 | if (ret) |
739 | goto out; | |
740 | } | |
741 | ||
eb28be2b AK |
742 | if (dio_bio_add_page(sdio) != 0) { |
743 | dio_bio_submit(dio, sdio); | |
18772641 | 744 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 | 745 | if (ret == 0) { |
eb28be2b | 746 | ret = dio_bio_add_page(sdio); |
1da177e4 LT |
747 | BUG_ON(ret != 0); |
748 | } | |
749 | } | |
750 | out: | |
751 | return ret; | |
752 | } | |
753 | ||
754 | /* | |
755 | * An autonomous function to put a chunk of a page under deferred IO. | |
756 | * | |
757 | * The caller doesn't actually know (or care) whether this piece of page is in | |
758 | * a BIO, or is under IO or whatever. We just take care of all possible | |
759 | * situations here. The separation between the logic of do_direct_IO() and | |
760 | * that of submit_page_section() is important for clarity. Please don't break. | |
761 | * | |
762 | * The chunk of page starts on-disk at blocknr. | |
763 | * | |
764 | * We perform deferred IO, by recording the last-submitted page inside our | |
765 | * private part of the dio structure. If possible, we just expand the IO | |
766 | * across that page here. | |
767 | * | |
768 | * If that doesn't work out then we put the old page into the bio and add this | |
769 | * page to the dio instead. | |
770 | */ | |
ba253fbf | 771 | static inline int |
eb28be2b | 772 | submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, |
18772641 AK |
773 | unsigned offset, unsigned len, sector_t blocknr, |
774 | struct buffer_head *map_bh) | |
1da177e4 LT |
775 | { |
776 | int ret = 0; | |
777 | ||
98c4d57d AM |
778 | if (dio->rw & WRITE) { |
779 | /* | |
780 | * Read accounting is performed in submit_bio() | |
781 | */ | |
782 | task_io_account_write(len); | |
783 | } | |
784 | ||
1da177e4 LT |
785 | /* |
786 | * Can we just grow the current page's presence in the dio? | |
787 | */ | |
eb28be2b AK |
788 | if (sdio->cur_page == page && |
789 | sdio->cur_page_offset + sdio->cur_page_len == offset && | |
790 | sdio->cur_page_block + | |
791 | (sdio->cur_page_len >> sdio->blkbits) == blocknr) { | |
792 | sdio->cur_page_len += len; | |
1da177e4 LT |
793 | goto out; |
794 | } | |
795 | ||
796 | /* | |
797 | * If there's a deferred page already there then send it. | |
798 | */ | |
eb28be2b | 799 | if (sdio->cur_page) { |
18772641 | 800 | ret = dio_send_cur_page(dio, sdio, map_bh); |
eb28be2b AK |
801 | page_cache_release(sdio->cur_page); |
802 | sdio->cur_page = NULL; | |
1da177e4 | 803 | if (ret) |
b1058b98 | 804 | return ret; |
1da177e4 LT |
805 | } |
806 | ||
807 | page_cache_get(page); /* It is in dio */ | |
eb28be2b AK |
808 | sdio->cur_page = page; |
809 | sdio->cur_page_offset = offset; | |
810 | sdio->cur_page_len = len; | |
811 | sdio->cur_page_block = blocknr; | |
812 | sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits; | |
1da177e4 | 813 | out: |
b1058b98 JK |
814 | /* |
815 | * If sdio->boundary then we want to schedule the IO now to | |
816 | * avoid metadata seeks. | |
817 | */ | |
818 | if (sdio->boundary) { | |
819 | ret = dio_send_cur_page(dio, sdio, map_bh); | |
820 | dio_bio_submit(dio, sdio); | |
821 | page_cache_release(sdio->cur_page); | |
822 | sdio->cur_page = NULL; | |
823 | } | |
1da177e4 LT |
824 | return ret; |
825 | } | |
826 | ||
827 | /* | |
828 | * Clean any dirty buffers in the blockdev mapping which alias newly-created | |
829 | * file blocks. Only called for S_ISREG files - blockdevs do not set | |
830 | * buffer_new | |
831 | */ | |
18772641 | 832 | static void clean_blockdev_aliases(struct dio *dio, struct buffer_head *map_bh) |
1da177e4 LT |
833 | { |
834 | unsigned i; | |
835 | unsigned nblocks; | |
836 | ||
18772641 | 837 | nblocks = map_bh->b_size >> dio->inode->i_blkbits; |
1da177e4 LT |
838 | |
839 | for (i = 0; i < nblocks; i++) { | |
18772641 AK |
840 | unmap_underlying_metadata(map_bh->b_bdev, |
841 | map_bh->b_blocknr + i); | |
1da177e4 LT |
842 | } |
843 | } | |
844 | ||
845 | /* | |
846 | * If we are not writing the entire block and get_block() allocated | |
847 | * the block for us, we need to fill-in the unused portion of the | |
848 | * block with zeros. This happens only if user-buffer, fileoffset or | |
849 | * io length is not filesystem block-size multiple. | |
850 | * | |
851 | * `end' is zero if we're doing the start of the IO, 1 at the end of the | |
852 | * IO. | |
853 | */ | |
ba253fbf AK |
854 | static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio, |
855 | int end, struct buffer_head *map_bh) | |
1da177e4 LT |
856 | { |
857 | unsigned dio_blocks_per_fs_block; | |
858 | unsigned this_chunk_blocks; /* In dio_blocks */ | |
859 | unsigned this_chunk_bytes; | |
860 | struct page *page; | |
861 | ||
eb28be2b | 862 | sdio->start_zero_done = 1; |
18772641 | 863 | if (!sdio->blkfactor || !buffer_new(map_bh)) |
1da177e4 LT |
864 | return; |
865 | ||
eb28be2b AK |
866 | dio_blocks_per_fs_block = 1 << sdio->blkfactor; |
867 | this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1); | |
1da177e4 LT |
868 | |
869 | if (!this_chunk_blocks) | |
870 | return; | |
871 | ||
872 | /* | |
873 | * We need to zero out part of an fs block. It is either at the | |
874 | * beginning or the end of the fs block. | |
875 | */ | |
876 | if (end) | |
877 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; | |
878 | ||
eb28be2b | 879 | this_chunk_bytes = this_chunk_blocks << sdio->blkbits; |
1da177e4 | 880 | |
557ed1fa | 881 | page = ZERO_PAGE(0); |
eb28be2b | 882 | if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes, |
18772641 | 883 | sdio->next_block_for_io, map_bh)) |
1da177e4 LT |
884 | return; |
885 | ||
eb28be2b | 886 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 LT |
887 | } |
888 | ||
889 | /* | |
890 | * Walk the user pages, and the file, mapping blocks to disk and generating | |
891 | * a sequence of (page,offset,len,block) mappings. These mappings are injected | |
892 | * into submit_page_section(), which takes care of the next stage of submission | |
893 | * | |
894 | * Direct IO against a blockdev is different from a file. Because we can | |
895 | * happily perform page-sized but 512-byte aligned IOs. It is important that | |
896 | * blockdev IO be able to have fine alignment and large sizes. | |
897 | * | |
1d8fa7a2 | 898 | * So what we do is to permit the ->get_block function to populate bh.b_size |
1da177e4 LT |
899 | * with the size of IO which is permitted at this offset and this i_blkbits. |
900 | * | |
901 | * For best results, the blockdev should be set up with 512-byte i_blkbits and | |
1d8fa7a2 | 902 | * it should set b_size to PAGE_SIZE or more inside get_block(). This gives |
1da177e4 LT |
903 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
904 | */ | |
18772641 AK |
905 | static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, |
906 | struct buffer_head *map_bh) | |
1da177e4 | 907 | { |
eb28be2b | 908 | const unsigned blkbits = sdio->blkbits; |
1da177e4 LT |
909 | int ret = 0; |
910 | ||
eb28be2b | 911 | while (sdio->block_in_file < sdio->final_block_in_request) { |
7b2c99d1 AV |
912 | struct page *page; |
913 | size_t from, to; | |
6fcc5420 BH |
914 | |
915 | page = dio_get_page(dio, sdio); | |
1da177e4 LT |
916 | if (IS_ERR(page)) { |
917 | ret = PTR_ERR(page); | |
918 | goto out; | |
919 | } | |
6fcc5420 BH |
920 | from = sdio->head ? 0 : sdio->from; |
921 | to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE; | |
922 | sdio->head++; | |
1da177e4 | 923 | |
7b2c99d1 | 924 | while (from < to) { |
1da177e4 LT |
925 | unsigned this_chunk_bytes; /* # of bytes mapped */ |
926 | unsigned this_chunk_blocks; /* # of blocks */ | |
927 | unsigned u; | |
928 | ||
eb28be2b | 929 | if (sdio->blocks_available == 0) { |
1da177e4 LT |
930 | /* |
931 | * Need to go and map some more disk | |
932 | */ | |
933 | unsigned long blkmask; | |
934 | unsigned long dio_remainder; | |
935 | ||
18772641 | 936 | ret = get_more_blocks(dio, sdio, map_bh); |
1da177e4 LT |
937 | if (ret) { |
938 | page_cache_release(page); | |
939 | goto out; | |
940 | } | |
941 | if (!buffer_mapped(map_bh)) | |
942 | goto do_holes; | |
943 | ||
eb28be2b AK |
944 | sdio->blocks_available = |
945 | map_bh->b_size >> sdio->blkbits; | |
946 | sdio->next_block_for_io = | |
947 | map_bh->b_blocknr << sdio->blkfactor; | |
1da177e4 | 948 | if (buffer_new(map_bh)) |
18772641 | 949 | clean_blockdev_aliases(dio, map_bh); |
1da177e4 | 950 | |
eb28be2b | 951 | if (!sdio->blkfactor) |
1da177e4 LT |
952 | goto do_holes; |
953 | ||
eb28be2b AK |
954 | blkmask = (1 << sdio->blkfactor) - 1; |
955 | dio_remainder = (sdio->block_in_file & blkmask); | |
1da177e4 LT |
956 | |
957 | /* | |
958 | * If we are at the start of IO and that IO | |
959 | * starts partway into a fs-block, | |
960 | * dio_remainder will be non-zero. If the IO | |
961 | * is a read then we can simply advance the IO | |
962 | * cursor to the first block which is to be | |
963 | * read. But if the IO is a write and the | |
964 | * block was newly allocated we cannot do that; | |
965 | * the start of the fs block must be zeroed out | |
966 | * on-disk | |
967 | */ | |
968 | if (!buffer_new(map_bh)) | |
eb28be2b AK |
969 | sdio->next_block_for_io += dio_remainder; |
970 | sdio->blocks_available -= dio_remainder; | |
1da177e4 LT |
971 | } |
972 | do_holes: | |
973 | /* Handle holes */ | |
974 | if (!buffer_mapped(map_bh)) { | |
35dc8161 | 975 | loff_t i_size_aligned; |
1da177e4 LT |
976 | |
977 | /* AKPM: eargh, -ENOTBLK is a hack */ | |
b31dc66a | 978 | if (dio->rw & WRITE) { |
1da177e4 LT |
979 | page_cache_release(page); |
980 | return -ENOTBLK; | |
981 | } | |
982 | ||
35dc8161 JM |
983 | /* |
984 | * Be sure to account for a partial block as the | |
985 | * last block in the file | |
986 | */ | |
987 | i_size_aligned = ALIGN(i_size_read(dio->inode), | |
988 | 1 << blkbits); | |
eb28be2b | 989 | if (sdio->block_in_file >= |
35dc8161 | 990 | i_size_aligned >> blkbits) { |
1da177e4 LT |
991 | /* We hit eof */ |
992 | page_cache_release(page); | |
993 | goto out; | |
994 | } | |
7b2c99d1 | 995 | zero_user(page, from, 1 << blkbits); |
eb28be2b | 996 | sdio->block_in_file++; |
7b2c99d1 | 997 | from += 1 << blkbits; |
3320c60b | 998 | dio->result += 1 << blkbits; |
1da177e4 LT |
999 | goto next_block; |
1000 | } | |
1001 | ||
1002 | /* | |
1003 | * If we're performing IO which has an alignment which | |
1004 | * is finer than the underlying fs, go check to see if | |
1005 | * we must zero out the start of this block. | |
1006 | */ | |
eb28be2b | 1007 | if (unlikely(sdio->blkfactor && !sdio->start_zero_done)) |
18772641 | 1008 | dio_zero_block(dio, sdio, 0, map_bh); |
1da177e4 LT |
1009 | |
1010 | /* | |
1011 | * Work out, in this_chunk_blocks, how much disk we | |
1012 | * can add to this page | |
1013 | */ | |
eb28be2b | 1014 | this_chunk_blocks = sdio->blocks_available; |
7b2c99d1 | 1015 | u = (to - from) >> blkbits; |
1da177e4 LT |
1016 | if (this_chunk_blocks > u) |
1017 | this_chunk_blocks = u; | |
eb28be2b | 1018 | u = sdio->final_block_in_request - sdio->block_in_file; |
1da177e4 LT |
1019 | if (this_chunk_blocks > u) |
1020 | this_chunk_blocks = u; | |
1021 | this_chunk_bytes = this_chunk_blocks << blkbits; | |
1022 | BUG_ON(this_chunk_bytes == 0); | |
1023 | ||
092c8d46 JK |
1024 | if (this_chunk_blocks == sdio->blocks_available) |
1025 | sdio->boundary = buffer_boundary(map_bh); | |
eb28be2b | 1026 | ret = submit_page_section(dio, sdio, page, |
7b2c99d1 | 1027 | from, |
eb28be2b | 1028 | this_chunk_bytes, |
18772641 AK |
1029 | sdio->next_block_for_io, |
1030 | map_bh); | |
1da177e4 LT |
1031 | if (ret) { |
1032 | page_cache_release(page); | |
1033 | goto out; | |
1034 | } | |
eb28be2b | 1035 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 | 1036 | |
eb28be2b | 1037 | sdio->block_in_file += this_chunk_blocks; |
7b2c99d1 AV |
1038 | from += this_chunk_bytes; |
1039 | dio->result += this_chunk_bytes; | |
eb28be2b | 1040 | sdio->blocks_available -= this_chunk_blocks; |
1da177e4 | 1041 | next_block: |
eb28be2b AK |
1042 | BUG_ON(sdio->block_in_file > sdio->final_block_in_request); |
1043 | if (sdio->block_in_file == sdio->final_block_in_request) | |
1da177e4 LT |
1044 | break; |
1045 | } | |
1046 | ||
1047 | /* Drop the ref which was taken in get_user_pages() */ | |
1048 | page_cache_release(page); | |
1da177e4 LT |
1049 | } |
1050 | out: | |
1051 | return ret; | |
1052 | } | |
1053 | ||
847cc637 | 1054 | static inline int drop_refcount(struct dio *dio) |
1da177e4 | 1055 | { |
847cc637 | 1056 | int ret2; |
5eb6c7a2 | 1057 | unsigned long flags; |
1da177e4 | 1058 | |
8459d86a ZB |
1059 | /* |
1060 | * Sync will always be dropping the final ref and completing the | |
5eb6c7a2 ZB |
1061 | * operation. AIO can if it was a broken operation described above or |
1062 | * in fact if all the bios race to complete before we get here. In | |
1063 | * that case dio_complete() translates the EIOCBQUEUED into the proper | |
04b2fa9f | 1064 | * return code that the caller will hand to ->complete(). |
5eb6c7a2 ZB |
1065 | * |
1066 | * This is managed by the bio_lock instead of being an atomic_t so that | |
1067 | * completion paths can drop their ref and use the remaining count to | |
1068 | * decide to wake the submission path atomically. | |
8459d86a | 1069 | */ |
5eb6c7a2 ZB |
1070 | spin_lock_irqsave(&dio->bio_lock, flags); |
1071 | ret2 = --dio->refcount; | |
1072 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
847cc637 | 1073 | return ret2; |
1da177e4 LT |
1074 | } |
1075 | ||
eafdc7d1 CH |
1076 | /* |
1077 | * This is a library function for use by filesystem drivers. | |
1078 | * | |
1079 | * The locking rules are governed by the flags parameter: | |
1080 | * - if the flags value contains DIO_LOCKING we use a fancy locking | |
1081 | * scheme for dumb filesystems. | |
1082 | * For writes this function is called under i_mutex and returns with | |
1083 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | |
1084 | * taken and dropped again before returning. | |
eafdc7d1 CH |
1085 | * - if the flags value does NOT contain DIO_LOCKING we don't use any |
1086 | * internal locking but rather rely on the filesystem to synchronize | |
1087 | * direct I/O reads/writes versus each other and truncate. | |
df2d6f26 CH |
1088 | * |
1089 | * To help with locking against truncate we incremented the i_dio_count | |
1090 | * counter before starting direct I/O, and decrement it once we are done. | |
1091 | * Truncate can wait for it to reach zero to provide exclusion. It is | |
1092 | * expected that filesystem provide exclusion between new direct I/O | |
1093 | * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, | |
1094 | * but other filesystems need to take care of this on their own. | |
ba253fbf AK |
1095 | * |
1096 | * NOTE: if you pass "sdio" to anything by pointer make sure that function | |
1097 | * is always inlined. Otherwise gcc is unable to split the structure into | |
1098 | * individual fields and will generate much worse code. This is important | |
1099 | * for the whole file. | |
eafdc7d1 | 1100 | */ |
65dd2aa9 | 1101 | static inline ssize_t |
17f8c842 OS |
1102 | do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, |
1103 | struct block_device *bdev, struct iov_iter *iter, | |
1104 | loff_t offset, get_block_t get_block, dio_iodone_t end_io, | |
1105 | dio_submit_t submit_io, int flags) | |
1da177e4 | 1106 | { |
ab73857e LT |
1107 | unsigned i_blkbits = ACCESS_ONCE(inode->i_blkbits); |
1108 | unsigned blkbits = i_blkbits; | |
1da177e4 LT |
1109 | unsigned blocksize_mask = (1 << blkbits) - 1; |
1110 | ssize_t retval = -EINVAL; | |
af436472 CH |
1111 | size_t count = iov_iter_count(iter); |
1112 | loff_t end = offset + count; | |
1da177e4 | 1113 | struct dio *dio; |
eb28be2b | 1114 | struct dio_submit sdio = { 0, }; |
847cc637 | 1115 | struct buffer_head map_bh = { 0, }; |
647d1e4c | 1116 | struct blk_plug plug; |
886a3911 | 1117 | unsigned long align = offset | iov_iter_alignment(iter); |
1da177e4 | 1118 | |
65dd2aa9 AK |
1119 | /* |
1120 | * Avoid references to bdev if not absolutely needed to give | |
1121 | * the early prefetch in the caller enough time. | |
1122 | */ | |
1da177e4 | 1123 | |
886a3911 | 1124 | if (align & blocksize_mask) { |
1da177e4 | 1125 | if (bdev) |
65dd2aa9 | 1126 | blkbits = blksize_bits(bdev_logical_block_size(bdev)); |
1da177e4 | 1127 | blocksize_mask = (1 << blkbits) - 1; |
886a3911 | 1128 | if (align & blocksize_mask) |
1da177e4 LT |
1129 | goto out; |
1130 | } | |
1131 | ||
f9b5570d | 1132 | /* watch out for a 0 len io from a tricksy fs */ |
17f8c842 | 1133 | if (iov_iter_rw(iter) == READ && !iov_iter_count(iter)) |
f9b5570d CH |
1134 | return 0; |
1135 | ||
6e8267f5 | 1136 | dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); |
1da177e4 LT |
1137 | retval = -ENOMEM; |
1138 | if (!dio) | |
1139 | goto out; | |
23aee091 JM |
1140 | /* |
1141 | * Believe it or not, zeroing out the page array caused a .5% | |
1142 | * performance regression in a database benchmark. So, we take | |
1143 | * care to only zero out what's needed. | |
1144 | */ | |
1145 | memset(dio, 0, offsetof(struct dio, pages)); | |
1da177e4 | 1146 | |
5fe878ae CH |
1147 | dio->flags = flags; |
1148 | if (dio->flags & DIO_LOCKING) { | |
17f8c842 | 1149 | if (iov_iter_rw(iter) == READ) { |
5fe878ae CH |
1150 | struct address_space *mapping = |
1151 | iocb->ki_filp->f_mapping; | |
1da177e4 | 1152 | |
5fe878ae CH |
1153 | /* will be released by direct_io_worker */ |
1154 | mutex_lock(&inode->i_mutex); | |
1da177e4 LT |
1155 | |
1156 | retval = filemap_write_and_wait_range(mapping, offset, | |
1157 | end - 1); | |
1158 | if (retval) { | |
5fe878ae | 1159 | mutex_unlock(&inode->i_mutex); |
6e8267f5 | 1160 | kmem_cache_free(dio_cache, dio); |
1da177e4 LT |
1161 | goto out; |
1162 | } | |
1da177e4 | 1163 | } |
1da177e4 LT |
1164 | } |
1165 | ||
1166 | /* | |
60392573 CH |
1167 | * For file extending writes updating i_size before data writeouts |
1168 | * complete can expose uninitialized blocks in dumb filesystems. | |
1169 | * In that case we need to wait for I/O completion even if asked | |
1170 | * for an asynchronous write. | |
1da177e4 | 1171 | */ |
60392573 CH |
1172 | if (is_sync_kiocb(iocb)) |
1173 | dio->is_async = false; | |
1174 | else if (!(dio->flags & DIO_ASYNC_EXTEND) && | |
17f8c842 | 1175 | iov_iter_rw(iter) == WRITE && end > i_size_read(inode)) |
60392573 CH |
1176 | dio->is_async = false; |
1177 | else | |
1178 | dio->is_async = true; | |
1179 | ||
847cc637 | 1180 | dio->inode = inode; |
17f8c842 | 1181 | dio->rw = iov_iter_rw(iter) == WRITE ? WRITE_ODIRECT : READ; |
02afc27f CH |
1182 | |
1183 | /* | |
1184 | * For AIO O_(D)SYNC writes we need to defer completions to a workqueue | |
1185 | * so that we can call ->fsync. | |
1186 | */ | |
17f8c842 | 1187 | if (dio->is_async && iov_iter_rw(iter) == WRITE && |
02afc27f CH |
1188 | ((iocb->ki_filp->f_flags & O_DSYNC) || |
1189 | IS_SYNC(iocb->ki_filp->f_mapping->host))) { | |
1190 | retval = dio_set_defer_completion(dio); | |
1191 | if (retval) { | |
1192 | /* | |
1193 | * We grab i_mutex only for reads so we don't have | |
1194 | * to release it here | |
1195 | */ | |
1196 | kmem_cache_free(dio_cache, dio); | |
1197 | goto out; | |
1198 | } | |
1199 | } | |
1200 | ||
1201 | /* | |
1202 | * Will be decremented at I/O completion time. | |
1203 | */ | |
fe0f07d0 JA |
1204 | if (!(dio->flags & DIO_SKIP_DIO_COUNT)) |
1205 | inode_dio_begin(inode); | |
02afc27f CH |
1206 | |
1207 | retval = 0; | |
847cc637 | 1208 | sdio.blkbits = blkbits; |
ab73857e | 1209 | sdio.blkfactor = i_blkbits - blkbits; |
847cc637 AK |
1210 | sdio.block_in_file = offset >> blkbits; |
1211 | ||
1212 | sdio.get_block = get_block; | |
1213 | dio->end_io = end_io; | |
1214 | sdio.submit_io = submit_io; | |
1215 | sdio.final_block_in_bio = -1; | |
1216 | sdio.next_block_for_io = -1; | |
1217 | ||
1218 | dio->iocb = iocb; | |
1219 | dio->i_size = i_size_read(inode); | |
1220 | ||
1221 | spin_lock_init(&dio->bio_lock); | |
1222 | dio->refcount = 1; | |
1223 | ||
53cbf3b1 | 1224 | dio->should_dirty = (iter->type == ITER_IOVEC); |
7b2c99d1 AV |
1225 | sdio.iter = iter; |
1226 | sdio.final_block_in_request = | |
1227 | (offset + iov_iter_count(iter)) >> blkbits; | |
1228 | ||
847cc637 AK |
1229 | /* |
1230 | * In case of non-aligned buffers, we may need 2 more | |
1231 | * pages since we need to zero out first and last block. | |
1232 | */ | |
1233 | if (unlikely(sdio.blkfactor)) | |
1234 | sdio.pages_in_io = 2; | |
1235 | ||
f67da30c | 1236 | sdio.pages_in_io += iov_iter_npages(iter, INT_MAX); |
847cc637 | 1237 | |
647d1e4c FW |
1238 | blk_start_plug(&plug); |
1239 | ||
7b2c99d1 AV |
1240 | retval = do_direct_IO(dio, &sdio, &map_bh); |
1241 | if (retval) | |
1242 | dio_cleanup(dio, &sdio); | |
847cc637 AK |
1243 | |
1244 | if (retval == -ENOTBLK) { | |
1245 | /* | |
1246 | * The remaining part of the request will be | |
1247 | * be handled by buffered I/O when we return | |
1248 | */ | |
1249 | retval = 0; | |
1250 | } | |
1251 | /* | |
1252 | * There may be some unwritten disk at the end of a part-written | |
1253 | * fs-block-sized block. Go zero that now. | |
1254 | */ | |
1255 | dio_zero_block(dio, &sdio, 1, &map_bh); | |
1256 | ||
1257 | if (sdio.cur_page) { | |
1258 | ssize_t ret2; | |
1259 | ||
1260 | ret2 = dio_send_cur_page(dio, &sdio, &map_bh); | |
1261 | if (retval == 0) | |
1262 | retval = ret2; | |
1263 | page_cache_release(sdio.cur_page); | |
1264 | sdio.cur_page = NULL; | |
1265 | } | |
1266 | if (sdio.bio) | |
1267 | dio_bio_submit(dio, &sdio); | |
1268 | ||
647d1e4c FW |
1269 | blk_finish_plug(&plug); |
1270 | ||
847cc637 AK |
1271 | /* |
1272 | * It is possible that, we return short IO due to end of file. | |
1273 | * In that case, we need to release all the pages we got hold on. | |
1274 | */ | |
1275 | dio_cleanup(dio, &sdio); | |
1276 | ||
1277 | /* | |
1278 | * All block lookups have been performed. For READ requests | |
1279 | * we can let i_mutex go now that its achieved its purpose | |
1280 | * of protecting us from looking up uninitialized blocks. | |
1281 | */ | |
17f8c842 | 1282 | if (iov_iter_rw(iter) == READ && (dio->flags & DIO_LOCKING)) |
847cc637 AK |
1283 | mutex_unlock(&dio->inode->i_mutex); |
1284 | ||
1285 | /* | |
1286 | * The only time we want to leave bios in flight is when a successful | |
1287 | * partial aio read or full aio write have been setup. In that case | |
1288 | * bio completion will call aio_complete. The only time it's safe to | |
1289 | * call aio_complete is when we return -EIOCBQUEUED, so we key on that. | |
1290 | * This had *better* be the only place that raises -EIOCBQUEUED. | |
1291 | */ | |
1292 | BUG_ON(retval == -EIOCBQUEUED); | |
1293 | if (dio->is_async && retval == 0 && dio->result && | |
17f8c842 | 1294 | (iov_iter_rw(iter) == READ || dio->result == count)) |
847cc637 | 1295 | retval = -EIOCBQUEUED; |
af436472 | 1296 | else |
847cc637 AK |
1297 | dio_await_completion(dio); |
1298 | ||
1299 | if (drop_refcount(dio) == 0) { | |
1300 | retval = dio_complete(dio, offset, retval, false); | |
847cc637 AK |
1301 | } else |
1302 | BUG_ON(retval != -EIOCBQUEUED); | |
1da177e4 | 1303 | |
7bb46a67 | 1304 | out: |
1305 | return retval; | |
1306 | } | |
65dd2aa9 | 1307 | |
17f8c842 OS |
1308 | ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, |
1309 | struct block_device *bdev, struct iov_iter *iter, | |
1310 | loff_t offset, get_block_t get_block, | |
1311 | dio_iodone_t end_io, dio_submit_t submit_io, | |
1312 | int flags) | |
65dd2aa9 AK |
1313 | { |
1314 | /* | |
1315 | * The block device state is needed in the end to finally | |
1316 | * submit everything. Since it's likely to be cache cold | |
1317 | * prefetch it here as first thing to hide some of the | |
1318 | * latency. | |
1319 | * | |
1320 | * Attempt to prefetch the pieces we likely need later. | |
1321 | */ | |
1322 | prefetch(&bdev->bd_disk->part_tbl); | |
1323 | prefetch(bdev->bd_queue); | |
1324 | prefetch((char *)bdev->bd_queue + SMP_CACHE_BYTES); | |
1325 | ||
17f8c842 OS |
1326 | return do_blockdev_direct_IO(iocb, inode, bdev, iter, offset, get_block, |
1327 | end_io, submit_io, flags); | |
65dd2aa9 AK |
1328 | } |
1329 | ||
1da177e4 | 1330 | EXPORT_SYMBOL(__blockdev_direct_IO); |
6e8267f5 AK |
1331 | |
1332 | static __init int dio_init(void) | |
1333 | { | |
1334 | dio_cache = KMEM_CACHE(dio, SLAB_PANIC); | |
1335 | return 0; | |
1336 | } | |
1337 | module_init(dio_init) |