Commit | Line | Data |
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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> |
1da177e4 LT |
39 | |
40 | /* | |
41 | * How many user pages to map in one call to get_user_pages(). This determines | |
cde1ecb3 | 42 | * the size of a structure in the slab cache |
1da177e4 LT |
43 | */ |
44 | #define DIO_PAGES 64 | |
45 | ||
46 | /* | |
47 | * This code generally works in units of "dio_blocks". A dio_block is | |
48 | * somewhere between the hard sector size and the filesystem block size. it | |
49 | * is determined on a per-invocation basis. When talking to the filesystem | |
50 | * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity | |
51 | * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted | |
52 | * to bio_block quantities by shifting left by blkfactor. | |
53 | * | |
54 | * If blkfactor is zero then the user's request was aligned to the filesystem's | |
55 | * blocksize. | |
1da177e4 LT |
56 | */ |
57 | ||
eb28be2b AK |
58 | /* dio_state only used in the submission path */ |
59 | ||
60 | struct dio_submit { | |
1da177e4 | 61 | struct bio *bio; /* bio under assembly */ |
1da177e4 LT |
62 | unsigned blkbits; /* doesn't change */ |
63 | unsigned blkfactor; /* When we're using an alignment which | |
64 | is finer than the filesystem's soft | |
65 | blocksize, this specifies how much | |
66 | finer. blkfactor=2 means 1/4-block | |
67 | alignment. Does not change */ | |
68 | unsigned start_zero_done; /* flag: sub-blocksize zeroing has | |
69 | been performed at the start of a | |
70 | write */ | |
71 | int pages_in_io; /* approximate total IO pages */ | |
72 | size_t size; /* total request size (doesn't change)*/ | |
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 LT |
77 | sector_t final_block_in_request;/* doesn't change */ |
78 | unsigned first_block_in_page; /* doesn't change, Used only once */ | |
79 | int boundary; /* prev block is at a boundary */ | |
1d8fa7a2 | 80 | get_block_t *get_block; /* block mapping function */ |
facd07b0 | 81 | dio_submit_t *submit_io; /* IO submition function */ |
eb28be2b | 82 | |
facd07b0 | 83 | loff_t logical_offset_in_bio; /* current first logical block in bio */ |
1da177e4 LT |
84 | sector_t final_block_in_bio; /* current final block in bio + 1 */ |
85 | sector_t next_block_for_io; /* next block to be put under IO, | |
86 | in dio_blocks units */ | |
1da177e4 LT |
87 | |
88 | /* | |
89 | * Deferred addition of a page to the dio. These variables are | |
90 | * private to dio_send_cur_page(), submit_page_section() and | |
91 | * dio_bio_add_page(). | |
92 | */ | |
93 | struct page *cur_page; /* The page */ | |
94 | unsigned cur_page_offset; /* Offset into it, in bytes */ | |
95 | unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ | |
96 | sector_t cur_page_block; /* Where it starts */ | |
facd07b0 | 97 | loff_t cur_page_fs_offset; /* Offset in file */ |
1da177e4 LT |
98 | |
99 | /* | |
100 | * Page fetching state. These variables belong to dio_refill_pages(). | |
101 | */ | |
102 | int curr_page; /* changes */ | |
103 | int total_pages; /* doesn't change */ | |
104 | unsigned long curr_user_address;/* changes */ | |
105 | ||
106 | /* | |
107 | * Page queue. These variables belong to dio_refill_pages() and | |
108 | * dio_get_page(). | |
109 | */ | |
1da177e4 LT |
110 | unsigned head; /* next page to process */ |
111 | unsigned tail; /* last valid page + 1 */ | |
eb28be2b AK |
112 | }; |
113 | ||
114 | /* dio_state communicated between submission path and end_io */ | |
115 | struct dio { | |
116 | int flags; /* doesn't change */ | |
eb28be2b | 117 | int rw; |
0dc2bc49 | 118 | struct inode *inode; |
eb28be2b AK |
119 | loff_t i_size; /* i_size when submitted */ |
120 | dio_iodone_t *end_io; /* IO completion function */ | |
eb28be2b AK |
121 | |
122 | ||
123 | /* BIO completion state */ | |
124 | spinlock_t bio_lock; /* protects BIO fields below */ | |
0dc2bc49 AK |
125 | int page_errors; /* errno from get_user_pages() */ |
126 | int is_async; /* is IO async ? */ | |
127 | int io_error; /* IO error in completion path */ | |
eb28be2b AK |
128 | unsigned long refcount; /* direct_io_worker() and bios */ |
129 | struct bio *bio_list; /* singly linked via bi_private */ | |
130 | struct task_struct *waiter; /* waiting task (NULL if none) */ | |
131 | ||
132 | /* AIO related stuff */ | |
133 | struct kiocb *iocb; /* kiocb */ | |
eb28be2b AK |
134 | ssize_t result; /* IO result */ |
135 | ||
0dc2bc49 | 136 | struct buffer_head map_bh; /* last get_block() result */ |
23aee091 JM |
137 | /* |
138 | * pages[] (and any fields placed after it) are not zeroed out at | |
139 | * allocation time. Don't add new fields after pages[] unless you | |
140 | * wish that they not be zeroed. | |
141 | */ | |
142 | struct page *pages[DIO_PAGES]; /* page buffer */ | |
6e8267f5 AK |
143 | } ____cacheline_aligned_in_smp; |
144 | ||
145 | static struct kmem_cache *dio_cache __read_mostly; | |
1da177e4 | 146 | |
bd5fe6c5 CH |
147 | static void __inode_dio_wait(struct inode *inode) |
148 | { | |
149 | wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP); | |
150 | DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP); | |
151 | ||
152 | do { | |
153 | prepare_to_wait(wq, &q.wait, TASK_UNINTERRUPTIBLE); | |
154 | if (atomic_read(&inode->i_dio_count)) | |
155 | schedule(); | |
156 | } while (atomic_read(&inode->i_dio_count)); | |
157 | finish_wait(wq, &q.wait); | |
158 | } | |
159 | ||
160 | /** | |
161 | * inode_dio_wait - wait for outstanding DIO requests to finish | |
162 | * @inode: inode to wait for | |
163 | * | |
164 | * Waits for all pending direct I/O requests to finish so that we can | |
165 | * proceed with a truncate or equivalent operation. | |
166 | * | |
167 | * Must be called under a lock that serializes taking new references | |
168 | * to i_dio_count, usually by inode->i_mutex. | |
169 | */ | |
170 | void inode_dio_wait(struct inode *inode) | |
171 | { | |
172 | if (atomic_read(&inode->i_dio_count)) | |
173 | __inode_dio_wait(inode); | |
174 | } | |
175 | EXPORT_SYMBOL_GPL(inode_dio_wait); | |
176 | ||
177 | /* | |
178 | * inode_dio_done - signal finish of a direct I/O requests | |
179 | * @inode: inode the direct I/O happens on | |
180 | * | |
181 | * This is called once we've finished processing a direct I/O request, | |
182 | * and is used to wake up callers waiting for direct I/O to be quiesced. | |
183 | */ | |
184 | void inode_dio_done(struct inode *inode) | |
185 | { | |
186 | if (atomic_dec_and_test(&inode->i_dio_count)) | |
187 | wake_up_bit(&inode->i_state, __I_DIO_WAKEUP); | |
188 | } | |
189 | EXPORT_SYMBOL_GPL(inode_dio_done); | |
190 | ||
1da177e4 LT |
191 | /* |
192 | * How many pages are in the queue? | |
193 | */ | |
eb28be2b | 194 | static inline unsigned dio_pages_present(struct dio_submit *sdio) |
1da177e4 | 195 | { |
eb28be2b | 196 | return sdio->tail - sdio->head; |
1da177e4 LT |
197 | } |
198 | ||
199 | /* | |
200 | * Go grab and pin some userspace pages. Typically we'll get 64 at a time. | |
201 | */ | |
eb28be2b | 202 | static int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
203 | { |
204 | int ret; | |
205 | int nr_pages; | |
206 | ||
eb28be2b | 207 | nr_pages = min(sdio->total_pages - sdio->curr_page, DIO_PAGES); |
f5dd33c4 | 208 | ret = get_user_pages_fast( |
eb28be2b | 209 | sdio->curr_user_address, /* Where from? */ |
1da177e4 LT |
210 | nr_pages, /* How many pages? */ |
211 | dio->rw == READ, /* Write to memory? */ | |
f5dd33c4 | 212 | &dio->pages[0]); /* Put results here */ |
1da177e4 | 213 | |
eb28be2b | 214 | if (ret < 0 && sdio->blocks_available && (dio->rw & WRITE)) { |
557ed1fa | 215 | struct page *page = ZERO_PAGE(0); |
1da177e4 LT |
216 | /* |
217 | * A memory fault, but the filesystem has some outstanding | |
218 | * mapped blocks. We need to use those blocks up to avoid | |
219 | * leaking stale data in the file. | |
220 | */ | |
221 | if (dio->page_errors == 0) | |
222 | dio->page_errors = ret; | |
b5810039 NP |
223 | page_cache_get(page); |
224 | dio->pages[0] = page; | |
eb28be2b AK |
225 | sdio->head = 0; |
226 | sdio->tail = 1; | |
1da177e4 LT |
227 | ret = 0; |
228 | goto out; | |
229 | } | |
230 | ||
231 | if (ret >= 0) { | |
eb28be2b AK |
232 | sdio->curr_user_address += ret * PAGE_SIZE; |
233 | sdio->curr_page += ret; | |
234 | sdio->head = 0; | |
235 | sdio->tail = ret; | |
1da177e4 LT |
236 | ret = 0; |
237 | } | |
238 | out: | |
239 | return ret; | |
240 | } | |
241 | ||
242 | /* | |
243 | * Get another userspace page. Returns an ERR_PTR on error. Pages are | |
244 | * buffered inside the dio so that we can call get_user_pages() against a | |
245 | * decent number of pages, less frequently. To provide nicer use of the | |
246 | * L1 cache. | |
247 | */ | |
eb28be2b | 248 | static struct page *dio_get_page(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 249 | { |
eb28be2b | 250 | if (dio_pages_present(sdio) == 0) { |
1da177e4 LT |
251 | int ret; |
252 | ||
eb28be2b | 253 | ret = dio_refill_pages(dio, sdio); |
1da177e4 LT |
254 | if (ret) |
255 | return ERR_PTR(ret); | |
eb28be2b | 256 | BUG_ON(dio_pages_present(sdio) == 0); |
1da177e4 | 257 | } |
eb28be2b | 258 | return dio->pages[sdio->head++]; |
1da177e4 LT |
259 | } |
260 | ||
6d544bb4 ZB |
261 | /** |
262 | * dio_complete() - called when all DIO BIO I/O has been completed | |
263 | * @offset: the byte offset in the file of the completed operation | |
264 | * | |
265 | * This releases locks as dictated by the locking type, lets interested parties | |
266 | * know that a DIO operation has completed, and calculates the resulting return | |
267 | * code for the operation. | |
268 | * | |
269 | * It lets the filesystem know if it registered an interest earlier via | |
270 | * get_block. Pass the private field of the map buffer_head so that | |
271 | * filesystems can use it to hold additional state between get_block calls and | |
272 | * dio_complete. | |
1da177e4 | 273 | */ |
cd1c584f | 274 | static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is_async) |
1da177e4 | 275 | { |
6d544bb4 ZB |
276 | ssize_t transferred = 0; |
277 | ||
8459d86a ZB |
278 | /* |
279 | * AIO submission can race with bio completion to get here while | |
280 | * expecting to have the last io completed by bio completion. | |
281 | * In that case -EIOCBQUEUED is in fact not an error we want | |
282 | * to preserve through this call. | |
283 | */ | |
284 | if (ret == -EIOCBQUEUED) | |
285 | ret = 0; | |
286 | ||
6d544bb4 ZB |
287 | if (dio->result) { |
288 | transferred = dio->result; | |
289 | ||
290 | /* Check for short read case */ | |
291 | if ((dio->rw == READ) && ((offset + transferred) > dio->i_size)) | |
292 | transferred = dio->i_size - offset; | |
293 | } | |
294 | ||
6d544bb4 ZB |
295 | if (ret == 0) |
296 | ret = dio->page_errors; | |
297 | if (ret == 0) | |
298 | ret = dio->io_error; | |
299 | if (ret == 0) | |
300 | ret = transferred; | |
301 | ||
40e2e973 CH |
302 | if (dio->end_io && dio->result) { |
303 | dio->end_io(dio->iocb, offset, transferred, | |
304 | dio->map_bh.b_private, ret, is_async); | |
72c5052d CH |
305 | } else { |
306 | if (is_async) | |
307 | aio_complete(dio->iocb, ret, 0); | |
308 | inode_dio_done(dio->inode); | |
40e2e973 CH |
309 | } |
310 | ||
6d544bb4 | 311 | return ret; |
1da177e4 LT |
312 | } |
313 | ||
1da177e4 LT |
314 | static int dio_bio_complete(struct dio *dio, struct bio *bio); |
315 | /* | |
316 | * Asynchronous IO callback. | |
317 | */ | |
6712ecf8 | 318 | static void dio_bio_end_aio(struct bio *bio, int error) |
1da177e4 LT |
319 | { |
320 | struct dio *dio = bio->bi_private; | |
5eb6c7a2 ZB |
321 | unsigned long remaining; |
322 | unsigned long flags; | |
1da177e4 | 323 | |
1da177e4 LT |
324 | /* cleanup the bio */ |
325 | dio_bio_complete(dio, bio); | |
0273201e | 326 | |
5eb6c7a2 ZB |
327 | spin_lock_irqsave(&dio->bio_lock, flags); |
328 | remaining = --dio->refcount; | |
329 | if (remaining == 1 && dio->waiter) | |
20258b2b | 330 | wake_up_process(dio->waiter); |
5eb6c7a2 | 331 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
20258b2b | 332 | |
8459d86a | 333 | if (remaining == 0) { |
40e2e973 | 334 | dio_complete(dio, dio->iocb->ki_pos, 0, true); |
6e8267f5 | 335 | kmem_cache_free(dio_cache, dio); |
8459d86a | 336 | } |
1da177e4 LT |
337 | } |
338 | ||
339 | /* | |
340 | * The BIO completion handler simply queues the BIO up for the process-context | |
341 | * handler. | |
342 | * | |
343 | * During I/O bi_private points at the dio. After I/O, bi_private is used to | |
344 | * implement a singly-linked list of completed BIOs, at dio->bio_list. | |
345 | */ | |
6712ecf8 | 346 | static void dio_bio_end_io(struct bio *bio, int error) |
1da177e4 LT |
347 | { |
348 | struct dio *dio = bio->bi_private; | |
349 | unsigned long flags; | |
350 | ||
1da177e4 LT |
351 | spin_lock_irqsave(&dio->bio_lock, flags); |
352 | bio->bi_private = dio->bio_list; | |
353 | dio->bio_list = bio; | |
5eb6c7a2 | 354 | if (--dio->refcount == 1 && dio->waiter) |
1da177e4 LT |
355 | wake_up_process(dio->waiter); |
356 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
1da177e4 LT |
357 | } |
358 | ||
facd07b0 JB |
359 | /** |
360 | * dio_end_io - handle the end io action for the given bio | |
361 | * @bio: The direct io bio thats being completed | |
362 | * @error: Error if there was one | |
363 | * | |
364 | * This is meant to be called by any filesystem that uses their own dio_submit_t | |
365 | * so that the DIO specific endio actions are dealt with after the filesystem | |
366 | * has done it's completion work. | |
367 | */ | |
368 | void dio_end_io(struct bio *bio, int error) | |
369 | { | |
370 | struct dio *dio = bio->bi_private; | |
371 | ||
372 | if (dio->is_async) | |
373 | dio_bio_end_aio(bio, error); | |
374 | else | |
375 | dio_bio_end_io(bio, error); | |
376 | } | |
377 | EXPORT_SYMBOL_GPL(dio_end_io); | |
378 | ||
20d9600c | 379 | static void |
eb28be2b AK |
380 | dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, |
381 | struct block_device *bdev, | |
382 | sector_t first_sector, int nr_vecs) | |
1da177e4 LT |
383 | { |
384 | struct bio *bio; | |
385 | ||
20d9600c DD |
386 | /* |
387 | * bio_alloc() is guaranteed to return a bio when called with | |
388 | * __GFP_WAIT and we request a valid number of vectors. | |
389 | */ | |
1da177e4 | 390 | bio = bio_alloc(GFP_KERNEL, nr_vecs); |
1da177e4 LT |
391 | |
392 | bio->bi_bdev = bdev; | |
393 | bio->bi_sector = first_sector; | |
394 | if (dio->is_async) | |
395 | bio->bi_end_io = dio_bio_end_aio; | |
396 | else | |
397 | bio->bi_end_io = dio_bio_end_io; | |
398 | ||
eb28be2b AK |
399 | sdio->bio = bio; |
400 | sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; | |
1da177e4 LT |
401 | } |
402 | ||
403 | /* | |
404 | * In the AIO read case we speculatively dirty the pages before starting IO. | |
405 | * During IO completion, any of these pages which happen to have been written | |
406 | * back will be redirtied by bio_check_pages_dirty(). | |
0273201e ZB |
407 | * |
408 | * bios hold a dio reference between submit_bio and ->end_io. | |
1da177e4 | 409 | */ |
eb28be2b | 410 | static void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 411 | { |
eb28be2b | 412 | struct bio *bio = sdio->bio; |
5eb6c7a2 | 413 | unsigned long flags; |
1da177e4 LT |
414 | |
415 | bio->bi_private = dio; | |
5eb6c7a2 ZB |
416 | |
417 | spin_lock_irqsave(&dio->bio_lock, flags); | |
418 | dio->refcount++; | |
419 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
420 | ||
1da177e4 LT |
421 | if (dio->is_async && dio->rw == READ) |
422 | bio_set_pages_dirty(bio); | |
5eb6c7a2 | 423 | |
eb28be2b AK |
424 | if (sdio->submit_io) |
425 | sdio->submit_io(dio->rw, bio, dio->inode, | |
426 | sdio->logical_offset_in_bio); | |
facd07b0 JB |
427 | else |
428 | submit_bio(dio->rw, bio); | |
1da177e4 | 429 | |
eb28be2b AK |
430 | sdio->bio = NULL; |
431 | sdio->boundary = 0; | |
432 | sdio->logical_offset_in_bio = 0; | |
1da177e4 LT |
433 | } |
434 | ||
435 | /* | |
436 | * Release any resources in case of a failure | |
437 | */ | |
eb28be2b | 438 | static void dio_cleanup(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 439 | { |
eb28be2b AK |
440 | while (dio_pages_present(sdio)) |
441 | page_cache_release(dio_get_page(dio, sdio)); | |
1da177e4 LT |
442 | } |
443 | ||
444 | /* | |
0273201e ZB |
445 | * Wait for the next BIO to complete. Remove it and return it. NULL is |
446 | * returned once all BIOs have been completed. This must only be called once | |
447 | * all bios have been issued so that dio->refcount can only decrease. This | |
448 | * requires that that the caller hold a reference on the dio. | |
1da177e4 LT |
449 | */ |
450 | static struct bio *dio_await_one(struct dio *dio) | |
451 | { | |
452 | unsigned long flags; | |
0273201e | 453 | struct bio *bio = NULL; |
1da177e4 LT |
454 | |
455 | spin_lock_irqsave(&dio->bio_lock, flags); | |
5eb6c7a2 ZB |
456 | |
457 | /* | |
458 | * Wait as long as the list is empty and there are bios in flight. bio | |
459 | * completion drops the count, maybe adds to the list, and wakes while | |
460 | * holding the bio_lock so we don't need set_current_state()'s barrier | |
461 | * and can call it after testing our condition. | |
462 | */ | |
463 | while (dio->refcount > 1 && dio->bio_list == NULL) { | |
464 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
465 | dio->waiter = current; | |
466 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
467 | io_schedule(); | |
468 | /* wake up sets us TASK_RUNNING */ | |
469 | spin_lock_irqsave(&dio->bio_lock, flags); | |
470 | dio->waiter = NULL; | |
1da177e4 | 471 | } |
0273201e ZB |
472 | if (dio->bio_list) { |
473 | bio = dio->bio_list; | |
474 | dio->bio_list = bio->bi_private; | |
475 | } | |
1da177e4 LT |
476 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
477 | return bio; | |
478 | } | |
479 | ||
480 | /* | |
481 | * Process one completed BIO. No locks are held. | |
482 | */ | |
483 | static int dio_bio_complete(struct dio *dio, struct bio *bio) | |
484 | { | |
485 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); | |
486 | struct bio_vec *bvec = bio->bi_io_vec; | |
487 | int page_no; | |
488 | ||
489 | if (!uptodate) | |
174e27c6 | 490 | dio->io_error = -EIO; |
1da177e4 LT |
491 | |
492 | if (dio->is_async && dio->rw == READ) { | |
493 | bio_check_pages_dirty(bio); /* transfers ownership */ | |
494 | } else { | |
495 | for (page_no = 0; page_no < bio->bi_vcnt; page_no++) { | |
496 | struct page *page = bvec[page_no].bv_page; | |
497 | ||
498 | if (dio->rw == READ && !PageCompound(page)) | |
499 | set_page_dirty_lock(page); | |
500 | page_cache_release(page); | |
501 | } | |
502 | bio_put(bio); | |
503 | } | |
1da177e4 LT |
504 | return uptodate ? 0 : -EIO; |
505 | } | |
506 | ||
507 | /* | |
0273201e ZB |
508 | * Wait on and process all in-flight BIOs. This must only be called once |
509 | * all bios have been issued so that the refcount can only decrease. | |
510 | * This just waits for all bios to make it through dio_bio_complete. IO | |
beb7dd86 | 511 | * errors are propagated through dio->io_error and should be propagated via |
0273201e | 512 | * dio_complete(). |
1da177e4 | 513 | */ |
6d544bb4 | 514 | static void dio_await_completion(struct dio *dio) |
1da177e4 | 515 | { |
0273201e ZB |
516 | struct bio *bio; |
517 | do { | |
518 | bio = dio_await_one(dio); | |
519 | if (bio) | |
520 | dio_bio_complete(dio, bio); | |
521 | } while (bio); | |
1da177e4 LT |
522 | } |
523 | ||
524 | /* | |
525 | * A really large O_DIRECT read or write can generate a lot of BIOs. So | |
526 | * to keep the memory consumption sane we periodically reap any completed BIOs | |
527 | * during the BIO generation phase. | |
528 | * | |
529 | * This also helps to limit the peak amount of pinned userspace memory. | |
530 | */ | |
eb28be2b | 531 | static int dio_bio_reap(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
532 | { |
533 | int ret = 0; | |
534 | ||
eb28be2b | 535 | if (sdio->reap_counter++ >= 64) { |
1da177e4 LT |
536 | while (dio->bio_list) { |
537 | unsigned long flags; | |
538 | struct bio *bio; | |
539 | int ret2; | |
540 | ||
541 | spin_lock_irqsave(&dio->bio_lock, flags); | |
542 | bio = dio->bio_list; | |
543 | dio->bio_list = bio->bi_private; | |
544 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
545 | ret2 = dio_bio_complete(dio, bio); | |
546 | if (ret == 0) | |
547 | ret = ret2; | |
548 | } | |
eb28be2b | 549 | sdio->reap_counter = 0; |
1da177e4 LT |
550 | } |
551 | return ret; | |
552 | } | |
553 | ||
554 | /* | |
555 | * Call into the fs to map some more disk blocks. We record the current number | |
eb28be2b | 556 | * of available blocks at sdio->blocks_available. These are in units of the |
1da177e4 LT |
557 | * fs blocksize, (1 << inode->i_blkbits). |
558 | * | |
559 | * The fs is allowed to map lots of blocks at once. If it wants to do that, | |
560 | * it uses the passed inode-relative block number as the file offset, as usual. | |
561 | * | |
1d8fa7a2 | 562 | * get_block() is passed the number of i_blkbits-sized blocks which direct_io |
1da177e4 LT |
563 | * has remaining to do. The fs should not map more than this number of blocks. |
564 | * | |
565 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to | |
566 | * indicate how much contiguous disk space has been made available at | |
567 | * bh->b_blocknr. | |
568 | * | |
569 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). | |
570 | * This isn't very efficient... | |
571 | * | |
572 | * In the case of filesystem holes: the fs may return an arbitrarily-large | |
573 | * hole by returning an appropriate value in b_size and by clearing | |
574 | * buffer_mapped(). However the direct-io code will only process holes one | |
1d8fa7a2 | 575 | * block at a time - it will repeatedly call get_block() as it walks the hole. |
1da177e4 | 576 | */ |
eb28be2b | 577 | static int get_more_blocks(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
578 | { |
579 | int ret; | |
580 | struct buffer_head *map_bh = &dio->map_bh; | |
581 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ | |
582 | unsigned long fs_count; /* Number of filesystem-sized blocks */ | |
583 | unsigned long dio_count;/* Number of dio_block-sized blocks */ | |
584 | unsigned long blkmask; | |
585 | int create; | |
586 | ||
587 | /* | |
588 | * If there was a memory error and we've overwritten all the | |
589 | * mapped blocks then we can now return that memory error | |
590 | */ | |
591 | ret = dio->page_errors; | |
592 | if (ret == 0) { | |
eb28be2b AK |
593 | BUG_ON(sdio->block_in_file >= sdio->final_block_in_request); |
594 | fs_startblk = sdio->block_in_file >> sdio->blkfactor; | |
595 | dio_count = sdio->final_block_in_request - sdio->block_in_file; | |
596 | fs_count = dio_count >> sdio->blkfactor; | |
597 | blkmask = (1 << sdio->blkfactor) - 1; | |
1da177e4 LT |
598 | if (dio_count & blkmask) |
599 | fs_count++; | |
600 | ||
3c674e74 NS |
601 | map_bh->b_state = 0; |
602 | map_bh->b_size = fs_count << dio->inode->i_blkbits; | |
603 | ||
5fe878ae CH |
604 | /* |
605 | * For writes inside i_size on a DIO_SKIP_HOLES filesystem we | |
606 | * forbid block creations: only overwrites are permitted. | |
607 | * We will return early to the caller once we see an | |
608 | * unmapped buffer head returned, and the caller will fall | |
609 | * back to buffered I/O. | |
610 | * | |
611 | * Otherwise the decision is left to the get_blocks method, | |
612 | * which may decide to handle it or also return an unmapped | |
613 | * buffer head. | |
614 | */ | |
b31dc66a | 615 | create = dio->rw & WRITE; |
5fe878ae | 616 | if (dio->flags & DIO_SKIP_HOLES) { |
eb28be2b AK |
617 | if (sdio->block_in_file < (i_size_read(dio->inode) >> |
618 | sdio->blkbits)) | |
1da177e4 | 619 | create = 0; |
1da177e4 | 620 | } |
3c674e74 | 621 | |
eb28be2b | 622 | ret = (*sdio->get_block)(dio->inode, fs_startblk, |
1da177e4 LT |
623 | map_bh, create); |
624 | } | |
625 | return ret; | |
626 | } | |
627 | ||
628 | /* | |
629 | * There is no bio. Make one now. | |
630 | */ | |
eb28be2b AK |
631 | static int dio_new_bio(struct dio *dio, struct dio_submit *sdio, |
632 | sector_t start_sector) | |
1da177e4 LT |
633 | { |
634 | sector_t sector; | |
635 | int ret, nr_pages; | |
636 | ||
eb28be2b | 637 | ret = dio_bio_reap(dio, sdio); |
1da177e4 LT |
638 | if (ret) |
639 | goto out; | |
eb28be2b AK |
640 | sector = start_sector << (sdio->blkbits - 9); |
641 | nr_pages = min(sdio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev)); | |
20d9600c | 642 | nr_pages = min(nr_pages, BIO_MAX_PAGES); |
1da177e4 | 643 | BUG_ON(nr_pages <= 0); |
eb28be2b AK |
644 | dio_bio_alloc(dio, sdio, dio->map_bh.b_bdev, sector, nr_pages); |
645 | sdio->boundary = 0; | |
1da177e4 LT |
646 | out: |
647 | return ret; | |
648 | } | |
649 | ||
650 | /* | |
651 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If | |
652 | * that was successful then update final_block_in_bio and take a ref against | |
653 | * the just-added page. | |
654 | * | |
655 | * Return zero on success. Non-zero means the caller needs to start a new BIO. | |
656 | */ | |
eb28be2b | 657 | static int dio_bio_add_page(struct dio_submit *sdio) |
1da177e4 LT |
658 | { |
659 | int ret; | |
660 | ||
eb28be2b AK |
661 | ret = bio_add_page(sdio->bio, sdio->cur_page, |
662 | sdio->cur_page_len, sdio->cur_page_offset); | |
663 | if (ret == sdio->cur_page_len) { | |
1da177e4 LT |
664 | /* |
665 | * Decrement count only, if we are done with this page | |
666 | */ | |
eb28be2b AK |
667 | if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE) |
668 | sdio->pages_in_io--; | |
669 | page_cache_get(sdio->cur_page); | |
670 | sdio->final_block_in_bio = sdio->cur_page_block + | |
671 | (sdio->cur_page_len >> sdio->blkbits); | |
1da177e4 LT |
672 | ret = 0; |
673 | } else { | |
674 | ret = 1; | |
675 | } | |
676 | return ret; | |
677 | } | |
678 | ||
679 | /* | |
680 | * Put cur_page under IO. The section of cur_page which is described by | |
681 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page | |
682 | * starts on-disk at cur_page_block. | |
683 | * | |
684 | * We take a ref against the page here (on behalf of its presence in the bio). | |
685 | * | |
686 | * The caller of this function is responsible for removing cur_page from the | |
687 | * dio, and for dropping the refcount which came from that presence. | |
688 | */ | |
eb28be2b | 689 | static int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
690 | { |
691 | int ret = 0; | |
692 | ||
eb28be2b AK |
693 | if (sdio->bio) { |
694 | loff_t cur_offset = sdio->cur_page_fs_offset; | |
695 | loff_t bio_next_offset = sdio->logical_offset_in_bio + | |
696 | sdio->bio->bi_size; | |
c2c6ca41 | 697 | |
1da177e4 | 698 | /* |
c2c6ca41 JB |
699 | * See whether this new request is contiguous with the old. |
700 | * | |
f0940cee NK |
701 | * Btrfs cannot handle having logically non-contiguous requests |
702 | * submitted. For example if you have | |
c2c6ca41 JB |
703 | * |
704 | * Logical: [0-4095][HOLE][8192-12287] | |
f0940cee | 705 | * Physical: [0-4095] [4096-8191] |
c2c6ca41 JB |
706 | * |
707 | * We cannot submit those pages together as one BIO. So if our | |
708 | * current logical offset in the file does not equal what would | |
709 | * be the next logical offset in the bio, submit the bio we | |
710 | * have. | |
1da177e4 | 711 | */ |
eb28be2b | 712 | if (sdio->final_block_in_bio != sdio->cur_page_block || |
c2c6ca41 | 713 | cur_offset != bio_next_offset) |
eb28be2b | 714 | dio_bio_submit(dio, sdio); |
1da177e4 LT |
715 | /* |
716 | * Submit now if the underlying fs is about to perform a | |
717 | * metadata read | |
718 | */ | |
eb28be2b AK |
719 | else if (sdio->boundary) |
720 | dio_bio_submit(dio, sdio); | |
1da177e4 LT |
721 | } |
722 | ||
eb28be2b AK |
723 | if (sdio->bio == NULL) { |
724 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block); | |
1da177e4 LT |
725 | if (ret) |
726 | goto out; | |
727 | } | |
728 | ||
eb28be2b AK |
729 | if (dio_bio_add_page(sdio) != 0) { |
730 | dio_bio_submit(dio, sdio); | |
731 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block); | |
1da177e4 | 732 | if (ret == 0) { |
eb28be2b | 733 | ret = dio_bio_add_page(sdio); |
1da177e4 LT |
734 | BUG_ON(ret != 0); |
735 | } | |
736 | } | |
737 | out: | |
738 | return ret; | |
739 | } | |
740 | ||
741 | /* | |
742 | * An autonomous function to put a chunk of a page under deferred IO. | |
743 | * | |
744 | * The caller doesn't actually know (or care) whether this piece of page is in | |
745 | * a BIO, or is under IO or whatever. We just take care of all possible | |
746 | * situations here. The separation between the logic of do_direct_IO() and | |
747 | * that of submit_page_section() is important for clarity. Please don't break. | |
748 | * | |
749 | * The chunk of page starts on-disk at blocknr. | |
750 | * | |
751 | * We perform deferred IO, by recording the last-submitted page inside our | |
752 | * private part of the dio structure. If possible, we just expand the IO | |
753 | * across that page here. | |
754 | * | |
755 | * If that doesn't work out then we put the old page into the bio and add this | |
756 | * page to the dio instead. | |
757 | */ | |
758 | static int | |
eb28be2b | 759 | submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, |
1da177e4 LT |
760 | unsigned offset, unsigned len, sector_t blocknr) |
761 | { | |
762 | int ret = 0; | |
763 | ||
98c4d57d AM |
764 | if (dio->rw & WRITE) { |
765 | /* | |
766 | * Read accounting is performed in submit_bio() | |
767 | */ | |
768 | task_io_account_write(len); | |
769 | } | |
770 | ||
1da177e4 LT |
771 | /* |
772 | * Can we just grow the current page's presence in the dio? | |
773 | */ | |
eb28be2b AK |
774 | if (sdio->cur_page == page && |
775 | sdio->cur_page_offset + sdio->cur_page_len == offset && | |
776 | sdio->cur_page_block + | |
777 | (sdio->cur_page_len >> sdio->blkbits) == blocknr) { | |
778 | sdio->cur_page_len += len; | |
1da177e4 LT |
779 | |
780 | /* | |
eb28be2b | 781 | * If sdio->boundary then we want to schedule the IO now to |
1da177e4 LT |
782 | * avoid metadata seeks. |
783 | */ | |
eb28be2b AK |
784 | if (sdio->boundary) { |
785 | ret = dio_send_cur_page(dio, sdio); | |
786 | page_cache_release(sdio->cur_page); | |
787 | sdio->cur_page = NULL; | |
1da177e4 LT |
788 | } |
789 | goto out; | |
790 | } | |
791 | ||
792 | /* | |
793 | * If there's a deferred page already there then send it. | |
794 | */ | |
eb28be2b AK |
795 | if (sdio->cur_page) { |
796 | ret = dio_send_cur_page(dio, sdio); | |
797 | page_cache_release(sdio->cur_page); | |
798 | sdio->cur_page = NULL; | |
1da177e4 LT |
799 | if (ret) |
800 | goto out; | |
801 | } | |
802 | ||
803 | page_cache_get(page); /* It is in dio */ | |
eb28be2b AK |
804 | sdio->cur_page = page; |
805 | sdio->cur_page_offset = offset; | |
806 | sdio->cur_page_len = len; | |
807 | sdio->cur_page_block = blocknr; | |
808 | sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits; | |
1da177e4 LT |
809 | out: |
810 | return ret; | |
811 | } | |
812 | ||
813 | /* | |
814 | * Clean any dirty buffers in the blockdev mapping which alias newly-created | |
815 | * file blocks. Only called for S_ISREG files - blockdevs do not set | |
816 | * buffer_new | |
817 | */ | |
818 | static void clean_blockdev_aliases(struct dio *dio) | |
819 | { | |
820 | unsigned i; | |
821 | unsigned nblocks; | |
822 | ||
823 | nblocks = dio->map_bh.b_size >> dio->inode->i_blkbits; | |
824 | ||
825 | for (i = 0; i < nblocks; i++) { | |
826 | unmap_underlying_metadata(dio->map_bh.b_bdev, | |
827 | dio->map_bh.b_blocknr + i); | |
828 | } | |
829 | } | |
830 | ||
831 | /* | |
832 | * If we are not writing the entire block and get_block() allocated | |
833 | * the block for us, we need to fill-in the unused portion of the | |
834 | * block with zeros. This happens only if user-buffer, fileoffset or | |
835 | * io length is not filesystem block-size multiple. | |
836 | * | |
837 | * `end' is zero if we're doing the start of the IO, 1 at the end of the | |
838 | * IO. | |
839 | */ | |
eb28be2b | 840 | static void dio_zero_block(struct dio *dio, struct dio_submit *sdio, int end) |
1da177e4 LT |
841 | { |
842 | unsigned dio_blocks_per_fs_block; | |
843 | unsigned this_chunk_blocks; /* In dio_blocks */ | |
844 | unsigned this_chunk_bytes; | |
845 | struct page *page; | |
846 | ||
eb28be2b AK |
847 | sdio->start_zero_done = 1; |
848 | if (!sdio->blkfactor || !buffer_new(&dio->map_bh)) | |
1da177e4 LT |
849 | return; |
850 | ||
eb28be2b AK |
851 | dio_blocks_per_fs_block = 1 << sdio->blkfactor; |
852 | this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1); | |
1da177e4 LT |
853 | |
854 | if (!this_chunk_blocks) | |
855 | return; | |
856 | ||
857 | /* | |
858 | * We need to zero out part of an fs block. It is either at the | |
859 | * beginning or the end of the fs block. | |
860 | */ | |
861 | if (end) | |
862 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; | |
863 | ||
eb28be2b | 864 | this_chunk_bytes = this_chunk_blocks << sdio->blkbits; |
1da177e4 | 865 | |
557ed1fa | 866 | page = ZERO_PAGE(0); |
eb28be2b AK |
867 | if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes, |
868 | sdio->next_block_for_io)) | |
1da177e4 LT |
869 | return; |
870 | ||
eb28be2b | 871 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 LT |
872 | } |
873 | ||
874 | /* | |
875 | * Walk the user pages, and the file, mapping blocks to disk and generating | |
876 | * a sequence of (page,offset,len,block) mappings. These mappings are injected | |
877 | * into submit_page_section(), which takes care of the next stage of submission | |
878 | * | |
879 | * Direct IO against a blockdev is different from a file. Because we can | |
880 | * happily perform page-sized but 512-byte aligned IOs. It is important that | |
881 | * blockdev IO be able to have fine alignment and large sizes. | |
882 | * | |
1d8fa7a2 | 883 | * So what we do is to permit the ->get_block function to populate bh.b_size |
1da177e4 LT |
884 | * with the size of IO which is permitted at this offset and this i_blkbits. |
885 | * | |
886 | * For best results, the blockdev should be set up with 512-byte i_blkbits and | |
1d8fa7a2 | 887 | * it should set b_size to PAGE_SIZE or more inside get_block(). This gives |
1da177e4 LT |
888 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
889 | */ | |
eb28be2b | 890 | static int do_direct_IO(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 891 | { |
eb28be2b | 892 | const unsigned blkbits = sdio->blkbits; |
1da177e4 LT |
893 | const unsigned blocks_per_page = PAGE_SIZE >> blkbits; |
894 | struct page *page; | |
895 | unsigned block_in_page; | |
896 | struct buffer_head *map_bh = &dio->map_bh; | |
897 | int ret = 0; | |
898 | ||
899 | /* The I/O can start at any block offset within the first page */ | |
eb28be2b | 900 | block_in_page = sdio->first_block_in_page; |
1da177e4 | 901 | |
eb28be2b AK |
902 | while (sdio->block_in_file < sdio->final_block_in_request) { |
903 | page = dio_get_page(dio, sdio); | |
1da177e4 LT |
904 | if (IS_ERR(page)) { |
905 | ret = PTR_ERR(page); | |
906 | goto out; | |
907 | } | |
908 | ||
909 | while (block_in_page < blocks_per_page) { | |
910 | unsigned offset_in_page = block_in_page << blkbits; | |
911 | unsigned this_chunk_bytes; /* # of bytes mapped */ | |
912 | unsigned this_chunk_blocks; /* # of blocks */ | |
913 | unsigned u; | |
914 | ||
eb28be2b | 915 | if (sdio->blocks_available == 0) { |
1da177e4 LT |
916 | /* |
917 | * Need to go and map some more disk | |
918 | */ | |
919 | unsigned long blkmask; | |
920 | unsigned long dio_remainder; | |
921 | ||
eb28be2b | 922 | ret = get_more_blocks(dio, sdio); |
1da177e4 LT |
923 | if (ret) { |
924 | page_cache_release(page); | |
925 | goto out; | |
926 | } | |
927 | if (!buffer_mapped(map_bh)) | |
928 | goto do_holes; | |
929 | ||
eb28be2b AK |
930 | sdio->blocks_available = |
931 | map_bh->b_size >> sdio->blkbits; | |
932 | sdio->next_block_for_io = | |
933 | map_bh->b_blocknr << sdio->blkfactor; | |
1da177e4 LT |
934 | if (buffer_new(map_bh)) |
935 | clean_blockdev_aliases(dio); | |
936 | ||
eb28be2b | 937 | if (!sdio->blkfactor) |
1da177e4 LT |
938 | goto do_holes; |
939 | ||
eb28be2b AK |
940 | blkmask = (1 << sdio->blkfactor) - 1; |
941 | dio_remainder = (sdio->block_in_file & blkmask); | |
1da177e4 LT |
942 | |
943 | /* | |
944 | * If we are at the start of IO and that IO | |
945 | * starts partway into a fs-block, | |
946 | * dio_remainder will be non-zero. If the IO | |
947 | * is a read then we can simply advance the IO | |
948 | * cursor to the first block which is to be | |
949 | * read. But if the IO is a write and the | |
950 | * block was newly allocated we cannot do that; | |
951 | * the start of the fs block must be zeroed out | |
952 | * on-disk | |
953 | */ | |
954 | if (!buffer_new(map_bh)) | |
eb28be2b AK |
955 | sdio->next_block_for_io += dio_remainder; |
956 | sdio->blocks_available -= dio_remainder; | |
1da177e4 LT |
957 | } |
958 | do_holes: | |
959 | /* Handle holes */ | |
960 | if (!buffer_mapped(map_bh)) { | |
35dc8161 | 961 | loff_t i_size_aligned; |
1da177e4 LT |
962 | |
963 | /* AKPM: eargh, -ENOTBLK is a hack */ | |
b31dc66a | 964 | if (dio->rw & WRITE) { |
1da177e4 LT |
965 | page_cache_release(page); |
966 | return -ENOTBLK; | |
967 | } | |
968 | ||
35dc8161 JM |
969 | /* |
970 | * Be sure to account for a partial block as the | |
971 | * last block in the file | |
972 | */ | |
973 | i_size_aligned = ALIGN(i_size_read(dio->inode), | |
974 | 1 << blkbits); | |
eb28be2b | 975 | if (sdio->block_in_file >= |
35dc8161 | 976 | i_size_aligned >> blkbits) { |
1da177e4 LT |
977 | /* We hit eof */ |
978 | page_cache_release(page); | |
979 | goto out; | |
980 | } | |
eebd2aa3 CL |
981 | zero_user(page, block_in_page << blkbits, |
982 | 1 << blkbits); | |
eb28be2b | 983 | sdio->block_in_file++; |
1da177e4 LT |
984 | block_in_page++; |
985 | goto next_block; | |
986 | } | |
987 | ||
988 | /* | |
989 | * If we're performing IO which has an alignment which | |
990 | * is finer than the underlying fs, go check to see if | |
991 | * we must zero out the start of this block. | |
992 | */ | |
eb28be2b AK |
993 | if (unlikely(sdio->blkfactor && !sdio->start_zero_done)) |
994 | dio_zero_block(dio, sdio, 0); | |
1da177e4 LT |
995 | |
996 | /* | |
997 | * Work out, in this_chunk_blocks, how much disk we | |
998 | * can add to this page | |
999 | */ | |
eb28be2b | 1000 | this_chunk_blocks = sdio->blocks_available; |
1da177e4 LT |
1001 | u = (PAGE_SIZE - offset_in_page) >> blkbits; |
1002 | if (this_chunk_blocks > u) | |
1003 | this_chunk_blocks = u; | |
eb28be2b | 1004 | u = sdio->final_block_in_request - sdio->block_in_file; |
1da177e4 LT |
1005 | if (this_chunk_blocks > u) |
1006 | this_chunk_blocks = u; | |
1007 | this_chunk_bytes = this_chunk_blocks << blkbits; | |
1008 | BUG_ON(this_chunk_bytes == 0); | |
1009 | ||
eb28be2b AK |
1010 | sdio->boundary = buffer_boundary(map_bh); |
1011 | ret = submit_page_section(dio, sdio, page, | |
1012 | offset_in_page, | |
1013 | this_chunk_bytes, | |
1014 | sdio->next_block_for_io); | |
1da177e4 LT |
1015 | if (ret) { |
1016 | page_cache_release(page); | |
1017 | goto out; | |
1018 | } | |
eb28be2b | 1019 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 | 1020 | |
eb28be2b | 1021 | sdio->block_in_file += this_chunk_blocks; |
1da177e4 | 1022 | block_in_page += this_chunk_blocks; |
eb28be2b | 1023 | sdio->blocks_available -= this_chunk_blocks; |
1da177e4 | 1024 | next_block: |
eb28be2b AK |
1025 | BUG_ON(sdio->block_in_file > sdio->final_block_in_request); |
1026 | if (sdio->block_in_file == sdio->final_block_in_request) | |
1da177e4 LT |
1027 | break; |
1028 | } | |
1029 | ||
1030 | /* Drop the ref which was taken in get_user_pages() */ | |
1031 | page_cache_release(page); | |
1032 | block_in_page = 0; | |
1033 | } | |
1034 | out: | |
1035 | return ret; | |
1036 | } | |
1037 | ||
1da177e4 LT |
1038 | static ssize_t |
1039 | direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, | |
1040 | const struct iovec *iov, loff_t offset, unsigned long nr_segs, | |
1d8fa7a2 | 1041 | unsigned blkbits, get_block_t get_block, dio_iodone_t end_io, |
eb28be2b | 1042 | dio_submit_t submit_io, struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
1043 | { |
1044 | unsigned long user_addr; | |
5eb6c7a2 | 1045 | unsigned long flags; |
1da177e4 LT |
1046 | int seg; |
1047 | ssize_t ret = 0; | |
1048 | ssize_t ret2; | |
1049 | size_t bytes; | |
1050 | ||
1da177e4 LT |
1051 | dio->inode = inode; |
1052 | dio->rw = rw; | |
eb28be2b AK |
1053 | sdio->blkbits = blkbits; |
1054 | sdio->blkfactor = inode->i_blkbits - blkbits; | |
1055 | sdio->block_in_file = offset >> blkbits; | |
1da177e4 | 1056 | |
eb28be2b | 1057 | sdio->get_block = get_block; |
1da177e4 | 1058 | dio->end_io = end_io; |
eb28be2b AK |
1059 | sdio->submit_io = submit_io; |
1060 | sdio->final_block_in_bio = -1; | |
1061 | sdio->next_block_for_io = -1; | |
1da177e4 | 1062 | |
1da177e4 | 1063 | dio->iocb = iocb; |
29504ff3 | 1064 | dio->i_size = i_size_read(inode); |
1da177e4 | 1065 | |
1da177e4 | 1066 | spin_lock_init(&dio->bio_lock); |
5eb6c7a2 | 1067 | dio->refcount = 1; |
1da177e4 LT |
1068 | |
1069 | /* | |
1070 | * In case of non-aligned buffers, we may need 2 more | |
1071 | * pages since we need to zero out first and last block. | |
1072 | */ | |
eb28be2b AK |
1073 | if (unlikely(sdio->blkfactor)) |
1074 | sdio->pages_in_io = 2; | |
1da177e4 LT |
1075 | |
1076 | for (seg = 0; seg < nr_segs; seg++) { | |
1077 | user_addr = (unsigned long)iov[seg].iov_base; | |
eb28be2b | 1078 | sdio->pages_in_io += |
1da177e4 LT |
1079 | ((user_addr+iov[seg].iov_len +PAGE_SIZE-1)/PAGE_SIZE |
1080 | - user_addr/PAGE_SIZE); | |
1081 | } | |
1082 | ||
1083 | for (seg = 0; seg < nr_segs; seg++) { | |
1084 | user_addr = (unsigned long)iov[seg].iov_base; | |
eb28be2b | 1085 | sdio->size += bytes = iov[seg].iov_len; |
1da177e4 LT |
1086 | |
1087 | /* Index into the first page of the first block */ | |
eb28be2b AK |
1088 | sdio->first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits; |
1089 | sdio->final_block_in_request = sdio->block_in_file + | |
1da177e4 LT |
1090 | (bytes >> blkbits); |
1091 | /* Page fetching state */ | |
eb28be2b AK |
1092 | sdio->head = 0; |
1093 | sdio->tail = 0; | |
1094 | sdio->curr_page = 0; | |
1da177e4 | 1095 | |
eb28be2b | 1096 | sdio->total_pages = 0; |
1da177e4 | 1097 | if (user_addr & (PAGE_SIZE-1)) { |
eb28be2b | 1098 | sdio->total_pages++; |
1da177e4 LT |
1099 | bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1)); |
1100 | } | |
eb28be2b AK |
1101 | sdio->total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE; |
1102 | sdio->curr_user_address = user_addr; | |
1da177e4 | 1103 | |
eb28be2b | 1104 | ret = do_direct_IO(dio, sdio); |
1da177e4 LT |
1105 | |
1106 | dio->result += iov[seg].iov_len - | |
eb28be2b | 1107 | ((sdio->final_block_in_request - sdio->block_in_file) << |
1da177e4 LT |
1108 | blkbits); |
1109 | ||
1110 | if (ret) { | |
eb28be2b | 1111 | dio_cleanup(dio, sdio); |
1da177e4 LT |
1112 | break; |
1113 | } | |
1114 | } /* end iovec loop */ | |
1115 | ||
facd07b0 | 1116 | if (ret == -ENOTBLK) { |
1da177e4 LT |
1117 | /* |
1118 | * The remaining part of the request will be | |
1119 | * be handled by buffered I/O when we return | |
1120 | */ | |
1121 | ret = 0; | |
1122 | } | |
1123 | /* | |
1124 | * There may be some unwritten disk at the end of a part-written | |
1125 | * fs-block-sized block. Go zero that now. | |
1126 | */ | |
eb28be2b | 1127 | dio_zero_block(dio, sdio, 1); |
1da177e4 | 1128 | |
eb28be2b AK |
1129 | if (sdio->cur_page) { |
1130 | ret2 = dio_send_cur_page(dio, sdio); | |
1da177e4 LT |
1131 | if (ret == 0) |
1132 | ret = ret2; | |
eb28be2b AK |
1133 | page_cache_release(sdio->cur_page); |
1134 | sdio->cur_page = NULL; | |
1da177e4 | 1135 | } |
eb28be2b AK |
1136 | if (sdio->bio) |
1137 | dio_bio_submit(dio, sdio); | |
1da177e4 LT |
1138 | |
1139 | /* | |
1140 | * It is possible that, we return short IO due to end of file. | |
1141 | * In that case, we need to release all the pages we got hold on. | |
1142 | */ | |
eb28be2b | 1143 | dio_cleanup(dio, sdio); |
1da177e4 LT |
1144 | |
1145 | /* | |
1146 | * All block lookups have been performed. For READ requests | |
1b1dcc1b | 1147 | * we can let i_mutex go now that its achieved its purpose |
1da177e4 LT |
1148 | * of protecting us from looking up uninitialized blocks. |
1149 | */ | |
5fe878ae | 1150 | if (rw == READ && (dio->flags & DIO_LOCKING)) |
1b1dcc1b | 1151 | mutex_unlock(&dio->inode->i_mutex); |
1da177e4 LT |
1152 | |
1153 | /* | |
8459d86a ZB |
1154 | * The only time we want to leave bios in flight is when a successful |
1155 | * partial aio read or full aio write have been setup. In that case | |
1156 | * bio completion will call aio_complete. The only time it's safe to | |
1157 | * call aio_complete is when we return -EIOCBQUEUED, so we key on that. | |
1158 | * This had *better* be the only place that raises -EIOCBQUEUED. | |
1da177e4 | 1159 | */ |
8459d86a ZB |
1160 | BUG_ON(ret == -EIOCBQUEUED); |
1161 | if (dio->is_async && ret == 0 && dio->result && | |
eb28be2b | 1162 | ((rw & READ) || (dio->result == sdio->size))) |
8459d86a | 1163 | ret = -EIOCBQUEUED; |
0273201e | 1164 | |
7eaceacc | 1165 | if (ret != -EIOCBQUEUED) |
6d544bb4 | 1166 | dio_await_completion(dio); |
1da177e4 | 1167 | |
8459d86a ZB |
1168 | /* |
1169 | * Sync will always be dropping the final ref and completing the | |
5eb6c7a2 ZB |
1170 | * operation. AIO can if it was a broken operation described above or |
1171 | * in fact if all the bios race to complete before we get here. In | |
1172 | * that case dio_complete() translates the EIOCBQUEUED into the proper | |
1173 | * return code that the caller will hand to aio_complete(). | |
1174 | * | |
1175 | * This is managed by the bio_lock instead of being an atomic_t so that | |
1176 | * completion paths can drop their ref and use the remaining count to | |
1177 | * decide to wake the submission path atomically. | |
8459d86a | 1178 | */ |
5eb6c7a2 ZB |
1179 | spin_lock_irqsave(&dio->bio_lock, flags); |
1180 | ret2 = --dio->refcount; | |
1181 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
fcb82f88 | 1182 | |
5eb6c7a2 | 1183 | if (ret2 == 0) { |
40e2e973 | 1184 | ret = dio_complete(dio, offset, ret, false); |
6e8267f5 | 1185 | kmem_cache_free(dio_cache, dio); |
8459d86a ZB |
1186 | } else |
1187 | BUG_ON(ret != -EIOCBQUEUED); | |
1da177e4 | 1188 | |
1da177e4 LT |
1189 | return ret; |
1190 | } | |
1191 | ||
eafdc7d1 CH |
1192 | /* |
1193 | * This is a library function for use by filesystem drivers. | |
1194 | * | |
1195 | * The locking rules are governed by the flags parameter: | |
1196 | * - if the flags value contains DIO_LOCKING we use a fancy locking | |
1197 | * scheme for dumb filesystems. | |
1198 | * For writes this function is called under i_mutex and returns with | |
1199 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | |
1200 | * taken and dropped again before returning. | |
eafdc7d1 CH |
1201 | * - if the flags value does NOT contain DIO_LOCKING we don't use any |
1202 | * internal locking but rather rely on the filesystem to synchronize | |
1203 | * direct I/O reads/writes versus each other and truncate. | |
df2d6f26 CH |
1204 | * |
1205 | * To help with locking against truncate we incremented the i_dio_count | |
1206 | * counter before starting direct I/O, and decrement it once we are done. | |
1207 | * Truncate can wait for it to reach zero to provide exclusion. It is | |
1208 | * expected that filesystem provide exclusion between new direct I/O | |
1209 | * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, | |
1210 | * but other filesystems need to take care of this on their own. | |
eafdc7d1 | 1211 | */ |
1da177e4 | 1212 | ssize_t |
eafdc7d1 | 1213 | __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, |
1da177e4 | 1214 | struct block_device *bdev, const struct iovec *iov, loff_t offset, |
1d8fa7a2 | 1215 | unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, |
facd07b0 | 1216 | dio_submit_t submit_io, int flags) |
1da177e4 LT |
1217 | { |
1218 | int seg; | |
1219 | size_t size; | |
1220 | unsigned long addr; | |
1221 | unsigned blkbits = inode->i_blkbits; | |
1222 | unsigned bdev_blkbits = 0; | |
1223 | unsigned blocksize_mask = (1 << blkbits) - 1; | |
1224 | ssize_t retval = -EINVAL; | |
1225 | loff_t end = offset; | |
1226 | struct dio *dio; | |
eb28be2b | 1227 | struct dio_submit sdio = { 0, }; |
1da177e4 LT |
1228 | |
1229 | if (rw & WRITE) | |
721a9602 | 1230 | rw = WRITE_ODIRECT; |
1da177e4 LT |
1231 | |
1232 | if (bdev) | |
e1defc4f | 1233 | bdev_blkbits = blksize_bits(bdev_logical_block_size(bdev)); |
1da177e4 LT |
1234 | |
1235 | if (offset & blocksize_mask) { | |
1236 | if (bdev) | |
1237 | blkbits = bdev_blkbits; | |
1238 | blocksize_mask = (1 << blkbits) - 1; | |
1239 | if (offset & blocksize_mask) | |
1240 | goto out; | |
1241 | } | |
1242 | ||
1243 | /* Check the memory alignment. Blocks cannot straddle pages */ | |
1244 | for (seg = 0; seg < nr_segs; seg++) { | |
1245 | addr = (unsigned long)iov[seg].iov_base; | |
1246 | size = iov[seg].iov_len; | |
1247 | end += size; | |
1248 | if ((addr & blocksize_mask) || (size & blocksize_mask)) { | |
1249 | if (bdev) | |
1250 | blkbits = bdev_blkbits; | |
1251 | blocksize_mask = (1 << blkbits) - 1; | |
1252 | if ((addr & blocksize_mask) || (size & blocksize_mask)) | |
1253 | goto out; | |
1254 | } | |
1255 | } | |
1256 | ||
f9b5570d CH |
1257 | /* watch out for a 0 len io from a tricksy fs */ |
1258 | if (rw == READ && end == offset) | |
1259 | return 0; | |
1260 | ||
6e8267f5 | 1261 | dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); |
1da177e4 LT |
1262 | retval = -ENOMEM; |
1263 | if (!dio) | |
1264 | goto out; | |
23aee091 JM |
1265 | /* |
1266 | * Believe it or not, zeroing out the page array caused a .5% | |
1267 | * performance regression in a database benchmark. So, we take | |
1268 | * care to only zero out what's needed. | |
1269 | */ | |
1270 | memset(dio, 0, offsetof(struct dio, pages)); | |
1da177e4 | 1271 | |
5fe878ae CH |
1272 | dio->flags = flags; |
1273 | if (dio->flags & DIO_LOCKING) { | |
f9b5570d | 1274 | if (rw == READ) { |
5fe878ae CH |
1275 | struct address_space *mapping = |
1276 | iocb->ki_filp->f_mapping; | |
1da177e4 | 1277 | |
5fe878ae CH |
1278 | /* will be released by direct_io_worker */ |
1279 | mutex_lock(&inode->i_mutex); | |
1da177e4 LT |
1280 | |
1281 | retval = filemap_write_and_wait_range(mapping, offset, | |
1282 | end - 1); | |
1283 | if (retval) { | |
5fe878ae | 1284 | mutex_unlock(&inode->i_mutex); |
6e8267f5 | 1285 | kmem_cache_free(dio_cache, dio); |
1da177e4 LT |
1286 | goto out; |
1287 | } | |
1da177e4 | 1288 | } |
1da177e4 LT |
1289 | } |
1290 | ||
df2d6f26 CH |
1291 | /* |
1292 | * Will be decremented at I/O completion time. | |
1293 | */ | |
1294 | atomic_inc(&inode->i_dio_count); | |
1295 | ||
1da177e4 LT |
1296 | /* |
1297 | * For file extending writes updating i_size before data | |
1298 | * writeouts complete can expose uninitialized blocks. So | |
1299 | * even for AIO, we need to wait for i/o to complete before | |
1300 | * returning in this case. | |
1301 | */ | |
b31dc66a | 1302 | dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) && |
1da177e4 LT |
1303 | (end > i_size_read(inode))); |
1304 | ||
1305 | retval = direct_io_worker(rw, iocb, inode, iov, offset, | |
facd07b0 | 1306 | nr_segs, blkbits, get_block, end_io, |
eb28be2b | 1307 | submit_io, dio, &sdio); |
1da177e4 | 1308 | |
7bb46a67 | 1309 | out: |
1310 | return retval; | |
1311 | } | |
1da177e4 | 1312 | EXPORT_SYMBOL(__blockdev_direct_IO); |
6e8267f5 AK |
1313 | |
1314 | static __init int dio_init(void) | |
1315 | { | |
1316 | dio_cache = KMEM_CACHE(dio, SLAB_PANIC); | |
1317 | return 0; | |
1318 | } | |
1319 | module_init(dio_init) |