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> | |
38 | #include <asm/atomic.h> | |
39 | ||
40 | /* | |
41 | * How many user pages to map in one call to get_user_pages(). This determines | |
42 | * the size of a structure on the stack. | |
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 | ||
58 | struct dio { | |
59 | /* BIO submission state */ | |
60 | struct bio *bio; /* bio under assembly */ | |
61 | struct inode *inode; | |
62 | int rw; | |
29504ff3 | 63 | loff_t i_size; /* i_size when submitted */ |
5fe878ae | 64 | int flags; /* doesn't change */ |
1da177e4 LT |
65 | unsigned blkbits; /* doesn't change */ |
66 | unsigned blkfactor; /* When we're using an alignment which | |
67 | is finer than the filesystem's soft | |
68 | blocksize, this specifies how much | |
69 | finer. blkfactor=2 means 1/4-block | |
70 | alignment. Does not change */ | |
71 | unsigned start_zero_done; /* flag: sub-blocksize zeroing has | |
72 | been performed at the start of a | |
73 | write */ | |
74 | int pages_in_io; /* approximate total IO pages */ | |
75 | size_t size; /* total request size (doesn't change)*/ | |
76 | sector_t block_in_file; /* Current offset into the underlying | |
77 | file in dio_block units. */ | |
78 | unsigned blocks_available; /* At block_in_file. changes */ | |
79 | sector_t final_block_in_request;/* doesn't change */ | |
80 | unsigned first_block_in_page; /* doesn't change, Used only once */ | |
81 | int boundary; /* prev block is at a boundary */ | |
82 | int reap_counter; /* rate limit reaping */ | |
1d8fa7a2 | 83 | get_block_t *get_block; /* block mapping function */ |
1da177e4 | 84 | dio_iodone_t *end_io; /* IO completion function */ |
facd07b0 JB |
85 | dio_submit_t *submit_io; /* IO submition function */ |
86 | loff_t logical_offset_in_bio; /* current first logical block in bio */ | |
1da177e4 LT |
87 | sector_t final_block_in_bio; /* current final block in bio + 1 */ |
88 | sector_t next_block_for_io; /* next block to be put under IO, | |
89 | in dio_blocks units */ | |
1d8fa7a2 | 90 | struct buffer_head map_bh; /* last get_block() result */ |
1da177e4 LT |
91 | |
92 | /* | |
93 | * Deferred addition of a page to the dio. These variables are | |
94 | * private to dio_send_cur_page(), submit_page_section() and | |
95 | * dio_bio_add_page(). | |
96 | */ | |
97 | struct page *cur_page; /* The page */ | |
98 | unsigned cur_page_offset; /* Offset into it, in bytes */ | |
99 | unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ | |
100 | sector_t cur_page_block; /* Where it starts */ | |
facd07b0 | 101 | loff_t cur_page_fs_offset; /* Offset in file */ |
1da177e4 | 102 | |
23aee091 JM |
103 | /* BIO completion state */ |
104 | spinlock_t bio_lock; /* protects BIO fields below */ | |
105 | unsigned long refcount; /* direct_io_worker() and bios */ | |
106 | struct bio *bio_list; /* singly linked via bi_private */ | |
107 | struct task_struct *waiter; /* waiting task (NULL if none) */ | |
108 | ||
109 | /* AIO related stuff */ | |
110 | struct kiocb *iocb; /* kiocb */ | |
111 | int is_async; /* is IO async ? */ | |
112 | int io_error; /* IO error in completion path */ | |
113 | ssize_t result; /* IO result */ | |
114 | ||
1da177e4 LT |
115 | /* |
116 | * Page fetching state. These variables belong to dio_refill_pages(). | |
117 | */ | |
118 | int curr_page; /* changes */ | |
119 | int total_pages; /* doesn't change */ | |
120 | unsigned long curr_user_address;/* changes */ | |
121 | ||
122 | /* | |
123 | * Page queue. These variables belong to dio_refill_pages() and | |
124 | * dio_get_page(). | |
125 | */ | |
1da177e4 LT |
126 | unsigned head; /* next page to process */ |
127 | unsigned tail; /* last valid page + 1 */ | |
128 | int page_errors; /* errno from get_user_pages() */ | |
129 | ||
23aee091 JM |
130 | /* |
131 | * pages[] (and any fields placed after it) are not zeroed out at | |
132 | * allocation time. Don't add new fields after pages[] unless you | |
133 | * wish that they not be zeroed. | |
134 | */ | |
135 | struct page *pages[DIO_PAGES]; /* page buffer */ | |
1da177e4 LT |
136 | }; |
137 | ||
bd5fe6c5 CH |
138 | static void __inode_dio_wait(struct inode *inode) |
139 | { | |
140 | wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP); | |
141 | DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP); | |
142 | ||
143 | do { | |
144 | prepare_to_wait(wq, &q.wait, TASK_UNINTERRUPTIBLE); | |
145 | if (atomic_read(&inode->i_dio_count)) | |
146 | schedule(); | |
147 | } while (atomic_read(&inode->i_dio_count)); | |
148 | finish_wait(wq, &q.wait); | |
149 | } | |
150 | ||
151 | /** | |
152 | * inode_dio_wait - wait for outstanding DIO requests to finish | |
153 | * @inode: inode to wait for | |
154 | * | |
155 | * Waits for all pending direct I/O requests to finish so that we can | |
156 | * proceed with a truncate or equivalent operation. | |
157 | * | |
158 | * Must be called under a lock that serializes taking new references | |
159 | * to i_dio_count, usually by inode->i_mutex. | |
160 | */ | |
161 | void inode_dio_wait(struct inode *inode) | |
162 | { | |
163 | if (atomic_read(&inode->i_dio_count)) | |
164 | __inode_dio_wait(inode); | |
165 | } | |
166 | EXPORT_SYMBOL_GPL(inode_dio_wait); | |
167 | ||
168 | /* | |
169 | * inode_dio_done - signal finish of a direct I/O requests | |
170 | * @inode: inode the direct I/O happens on | |
171 | * | |
172 | * This is called once we've finished processing a direct I/O request, | |
173 | * and is used to wake up callers waiting for direct I/O to be quiesced. | |
174 | */ | |
175 | void inode_dio_done(struct inode *inode) | |
176 | { | |
177 | if (atomic_dec_and_test(&inode->i_dio_count)) | |
178 | wake_up_bit(&inode->i_state, __I_DIO_WAKEUP); | |
179 | } | |
180 | EXPORT_SYMBOL_GPL(inode_dio_done); | |
181 | ||
1da177e4 LT |
182 | /* |
183 | * How many pages are in the queue? | |
184 | */ | |
185 | static inline unsigned dio_pages_present(struct dio *dio) | |
186 | { | |
187 | return dio->tail - dio->head; | |
188 | } | |
189 | ||
190 | /* | |
191 | * Go grab and pin some userspace pages. Typically we'll get 64 at a time. | |
192 | */ | |
193 | static int dio_refill_pages(struct dio *dio) | |
194 | { | |
195 | int ret; | |
196 | int nr_pages; | |
197 | ||
198 | nr_pages = min(dio->total_pages - dio->curr_page, DIO_PAGES); | |
f5dd33c4 | 199 | ret = get_user_pages_fast( |
1da177e4 LT |
200 | dio->curr_user_address, /* Where from? */ |
201 | nr_pages, /* How many pages? */ | |
202 | dio->rw == READ, /* Write to memory? */ | |
f5dd33c4 | 203 | &dio->pages[0]); /* Put results here */ |
1da177e4 | 204 | |
b31dc66a | 205 | if (ret < 0 && dio->blocks_available && (dio->rw & WRITE)) { |
557ed1fa | 206 | struct page *page = ZERO_PAGE(0); |
1da177e4 LT |
207 | /* |
208 | * A memory fault, but the filesystem has some outstanding | |
209 | * mapped blocks. We need to use those blocks up to avoid | |
210 | * leaking stale data in the file. | |
211 | */ | |
212 | if (dio->page_errors == 0) | |
213 | dio->page_errors = ret; | |
b5810039 NP |
214 | page_cache_get(page); |
215 | dio->pages[0] = page; | |
1da177e4 LT |
216 | dio->head = 0; |
217 | dio->tail = 1; | |
218 | ret = 0; | |
219 | goto out; | |
220 | } | |
221 | ||
222 | if (ret >= 0) { | |
223 | dio->curr_user_address += ret * PAGE_SIZE; | |
224 | dio->curr_page += ret; | |
225 | dio->head = 0; | |
226 | dio->tail = ret; | |
227 | ret = 0; | |
228 | } | |
229 | out: | |
230 | return ret; | |
231 | } | |
232 | ||
233 | /* | |
234 | * Get another userspace page. Returns an ERR_PTR on error. Pages are | |
235 | * buffered inside the dio so that we can call get_user_pages() against a | |
236 | * decent number of pages, less frequently. To provide nicer use of the | |
237 | * L1 cache. | |
238 | */ | |
239 | static struct page *dio_get_page(struct dio *dio) | |
240 | { | |
241 | if (dio_pages_present(dio) == 0) { | |
242 | int ret; | |
243 | ||
244 | ret = dio_refill_pages(dio); | |
245 | if (ret) | |
246 | return ERR_PTR(ret); | |
247 | BUG_ON(dio_pages_present(dio) == 0); | |
248 | } | |
249 | return dio->pages[dio->head++]; | |
250 | } | |
251 | ||
6d544bb4 ZB |
252 | /** |
253 | * dio_complete() - called when all DIO BIO I/O has been completed | |
254 | * @offset: the byte offset in the file of the completed operation | |
255 | * | |
256 | * This releases locks as dictated by the locking type, lets interested parties | |
257 | * know that a DIO operation has completed, and calculates the resulting return | |
258 | * code for the operation. | |
259 | * | |
260 | * It lets the filesystem know if it registered an interest earlier via | |
261 | * get_block. Pass the private field of the map buffer_head so that | |
262 | * filesystems can use it to hold additional state between get_block calls and | |
263 | * dio_complete. | |
1da177e4 | 264 | */ |
cd1c584f | 265 | static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is_async) |
1da177e4 | 266 | { |
6d544bb4 ZB |
267 | ssize_t transferred = 0; |
268 | ||
8459d86a ZB |
269 | /* |
270 | * AIO submission can race with bio completion to get here while | |
271 | * expecting to have the last io completed by bio completion. | |
272 | * In that case -EIOCBQUEUED is in fact not an error we want | |
273 | * to preserve through this call. | |
274 | */ | |
275 | if (ret == -EIOCBQUEUED) | |
276 | ret = 0; | |
277 | ||
6d544bb4 ZB |
278 | if (dio->result) { |
279 | transferred = dio->result; | |
280 | ||
281 | /* Check for short read case */ | |
282 | if ((dio->rw == READ) && ((offset + transferred) > dio->i_size)) | |
283 | transferred = dio->i_size - offset; | |
284 | } | |
285 | ||
6d544bb4 ZB |
286 | if (ret == 0) |
287 | ret = dio->page_errors; | |
288 | if (ret == 0) | |
289 | ret = dio->io_error; | |
290 | if (ret == 0) | |
291 | ret = transferred; | |
292 | ||
40e2e973 CH |
293 | if (dio->end_io && dio->result) { |
294 | dio->end_io(dio->iocb, offset, transferred, | |
295 | dio->map_bh.b_private, ret, is_async); | |
72c5052d CH |
296 | } else { |
297 | if (is_async) | |
298 | aio_complete(dio->iocb, ret, 0); | |
299 | inode_dio_done(dio->inode); | |
40e2e973 CH |
300 | } |
301 | ||
6d544bb4 | 302 | return ret; |
1da177e4 LT |
303 | } |
304 | ||
1da177e4 LT |
305 | static int dio_bio_complete(struct dio *dio, struct bio *bio); |
306 | /* | |
307 | * Asynchronous IO callback. | |
308 | */ | |
6712ecf8 | 309 | static void dio_bio_end_aio(struct bio *bio, int error) |
1da177e4 LT |
310 | { |
311 | struct dio *dio = bio->bi_private; | |
5eb6c7a2 ZB |
312 | unsigned long remaining; |
313 | unsigned long flags; | |
1da177e4 | 314 | |
1da177e4 LT |
315 | /* cleanup the bio */ |
316 | dio_bio_complete(dio, bio); | |
0273201e | 317 | |
5eb6c7a2 ZB |
318 | spin_lock_irqsave(&dio->bio_lock, flags); |
319 | remaining = --dio->refcount; | |
320 | if (remaining == 1 && dio->waiter) | |
20258b2b | 321 | wake_up_process(dio->waiter); |
5eb6c7a2 | 322 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
20258b2b | 323 | |
8459d86a | 324 | if (remaining == 0) { |
40e2e973 | 325 | dio_complete(dio, dio->iocb->ki_pos, 0, true); |
8459d86a ZB |
326 | kfree(dio); |
327 | } | |
1da177e4 LT |
328 | } |
329 | ||
330 | /* | |
331 | * The BIO completion handler simply queues the BIO up for the process-context | |
332 | * handler. | |
333 | * | |
334 | * During I/O bi_private points at the dio. After I/O, bi_private is used to | |
335 | * implement a singly-linked list of completed BIOs, at dio->bio_list. | |
336 | */ | |
6712ecf8 | 337 | static void dio_bio_end_io(struct bio *bio, int error) |
1da177e4 LT |
338 | { |
339 | struct dio *dio = bio->bi_private; | |
340 | unsigned long flags; | |
341 | ||
1da177e4 LT |
342 | spin_lock_irqsave(&dio->bio_lock, flags); |
343 | bio->bi_private = dio->bio_list; | |
344 | dio->bio_list = bio; | |
5eb6c7a2 | 345 | if (--dio->refcount == 1 && dio->waiter) |
1da177e4 LT |
346 | wake_up_process(dio->waiter); |
347 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
1da177e4 LT |
348 | } |
349 | ||
facd07b0 JB |
350 | /** |
351 | * dio_end_io - handle the end io action for the given bio | |
352 | * @bio: The direct io bio thats being completed | |
353 | * @error: Error if there was one | |
354 | * | |
355 | * This is meant to be called by any filesystem that uses their own dio_submit_t | |
356 | * so that the DIO specific endio actions are dealt with after the filesystem | |
357 | * has done it's completion work. | |
358 | */ | |
359 | void dio_end_io(struct bio *bio, int error) | |
360 | { | |
361 | struct dio *dio = bio->bi_private; | |
362 | ||
363 | if (dio->is_async) | |
364 | dio_bio_end_aio(bio, error); | |
365 | else | |
366 | dio_bio_end_io(bio, error); | |
367 | } | |
368 | EXPORT_SYMBOL_GPL(dio_end_io); | |
369 | ||
20d9600c | 370 | static void |
1da177e4 LT |
371 | dio_bio_alloc(struct dio *dio, struct block_device *bdev, |
372 | sector_t first_sector, int nr_vecs) | |
373 | { | |
374 | struct bio *bio; | |
375 | ||
20d9600c DD |
376 | /* |
377 | * bio_alloc() is guaranteed to return a bio when called with | |
378 | * __GFP_WAIT and we request a valid number of vectors. | |
379 | */ | |
1da177e4 | 380 | bio = bio_alloc(GFP_KERNEL, nr_vecs); |
1da177e4 LT |
381 | |
382 | bio->bi_bdev = bdev; | |
383 | bio->bi_sector = first_sector; | |
384 | if (dio->is_async) | |
385 | bio->bi_end_io = dio_bio_end_aio; | |
386 | else | |
387 | bio->bi_end_io = dio_bio_end_io; | |
388 | ||
389 | dio->bio = bio; | |
facd07b0 | 390 | dio->logical_offset_in_bio = dio->cur_page_fs_offset; |
1da177e4 LT |
391 | } |
392 | ||
393 | /* | |
394 | * In the AIO read case we speculatively dirty the pages before starting IO. | |
395 | * During IO completion, any of these pages which happen to have been written | |
396 | * back will be redirtied by bio_check_pages_dirty(). | |
0273201e ZB |
397 | * |
398 | * bios hold a dio reference between submit_bio and ->end_io. | |
1da177e4 LT |
399 | */ |
400 | static void dio_bio_submit(struct dio *dio) | |
401 | { | |
402 | struct bio *bio = dio->bio; | |
5eb6c7a2 | 403 | unsigned long flags; |
1da177e4 LT |
404 | |
405 | bio->bi_private = dio; | |
5eb6c7a2 ZB |
406 | |
407 | spin_lock_irqsave(&dio->bio_lock, flags); | |
408 | dio->refcount++; | |
409 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
410 | ||
1da177e4 LT |
411 | if (dio->is_async && dio->rw == READ) |
412 | bio_set_pages_dirty(bio); | |
5eb6c7a2 | 413 | |
facd07b0 JB |
414 | if (dio->submit_io) |
415 | dio->submit_io(dio->rw, bio, dio->inode, | |
416 | dio->logical_offset_in_bio); | |
417 | else | |
418 | submit_bio(dio->rw, bio); | |
1da177e4 LT |
419 | |
420 | dio->bio = NULL; | |
421 | dio->boundary = 0; | |
facd07b0 | 422 | dio->logical_offset_in_bio = 0; |
1da177e4 LT |
423 | } |
424 | ||
425 | /* | |
426 | * Release any resources in case of a failure | |
427 | */ | |
428 | static void dio_cleanup(struct dio *dio) | |
429 | { | |
430 | while (dio_pages_present(dio)) | |
431 | page_cache_release(dio_get_page(dio)); | |
432 | } | |
433 | ||
434 | /* | |
0273201e ZB |
435 | * Wait for the next BIO to complete. Remove it and return it. NULL is |
436 | * returned once all BIOs have been completed. This must only be called once | |
437 | * all bios have been issued so that dio->refcount can only decrease. This | |
438 | * requires that that the caller hold a reference on the dio. | |
1da177e4 LT |
439 | */ |
440 | static struct bio *dio_await_one(struct dio *dio) | |
441 | { | |
442 | unsigned long flags; | |
0273201e | 443 | struct bio *bio = NULL; |
1da177e4 LT |
444 | |
445 | spin_lock_irqsave(&dio->bio_lock, flags); | |
5eb6c7a2 ZB |
446 | |
447 | /* | |
448 | * Wait as long as the list is empty and there are bios in flight. bio | |
449 | * completion drops the count, maybe adds to the list, and wakes while | |
450 | * holding the bio_lock so we don't need set_current_state()'s barrier | |
451 | * and can call it after testing our condition. | |
452 | */ | |
453 | while (dio->refcount > 1 && dio->bio_list == NULL) { | |
454 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
455 | dio->waiter = current; | |
456 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
457 | io_schedule(); | |
458 | /* wake up sets us TASK_RUNNING */ | |
459 | spin_lock_irqsave(&dio->bio_lock, flags); | |
460 | dio->waiter = NULL; | |
1da177e4 | 461 | } |
0273201e ZB |
462 | if (dio->bio_list) { |
463 | bio = dio->bio_list; | |
464 | dio->bio_list = bio->bi_private; | |
465 | } | |
1da177e4 LT |
466 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
467 | return bio; | |
468 | } | |
469 | ||
470 | /* | |
471 | * Process one completed BIO. No locks are held. | |
472 | */ | |
473 | static int dio_bio_complete(struct dio *dio, struct bio *bio) | |
474 | { | |
475 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); | |
476 | struct bio_vec *bvec = bio->bi_io_vec; | |
477 | int page_no; | |
478 | ||
479 | if (!uptodate) | |
174e27c6 | 480 | dio->io_error = -EIO; |
1da177e4 LT |
481 | |
482 | if (dio->is_async && dio->rw == READ) { | |
483 | bio_check_pages_dirty(bio); /* transfers ownership */ | |
484 | } else { | |
485 | for (page_no = 0; page_no < bio->bi_vcnt; page_no++) { | |
486 | struct page *page = bvec[page_no].bv_page; | |
487 | ||
488 | if (dio->rw == READ && !PageCompound(page)) | |
489 | set_page_dirty_lock(page); | |
490 | page_cache_release(page); | |
491 | } | |
492 | bio_put(bio); | |
493 | } | |
1da177e4 LT |
494 | return uptodate ? 0 : -EIO; |
495 | } | |
496 | ||
497 | /* | |
0273201e ZB |
498 | * Wait on and process all in-flight BIOs. This must only be called once |
499 | * all bios have been issued so that the refcount can only decrease. | |
500 | * This just waits for all bios to make it through dio_bio_complete. IO | |
beb7dd86 | 501 | * errors are propagated through dio->io_error and should be propagated via |
0273201e | 502 | * dio_complete(). |
1da177e4 | 503 | */ |
6d544bb4 | 504 | static void dio_await_completion(struct dio *dio) |
1da177e4 | 505 | { |
0273201e ZB |
506 | struct bio *bio; |
507 | do { | |
508 | bio = dio_await_one(dio); | |
509 | if (bio) | |
510 | dio_bio_complete(dio, bio); | |
511 | } while (bio); | |
1da177e4 LT |
512 | } |
513 | ||
514 | /* | |
515 | * A really large O_DIRECT read or write can generate a lot of BIOs. So | |
516 | * to keep the memory consumption sane we periodically reap any completed BIOs | |
517 | * during the BIO generation phase. | |
518 | * | |
519 | * This also helps to limit the peak amount of pinned userspace memory. | |
520 | */ | |
521 | static int dio_bio_reap(struct dio *dio) | |
522 | { | |
523 | int ret = 0; | |
524 | ||
525 | if (dio->reap_counter++ >= 64) { | |
526 | while (dio->bio_list) { | |
527 | unsigned long flags; | |
528 | struct bio *bio; | |
529 | int ret2; | |
530 | ||
531 | spin_lock_irqsave(&dio->bio_lock, flags); | |
532 | bio = dio->bio_list; | |
533 | dio->bio_list = bio->bi_private; | |
534 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
535 | ret2 = dio_bio_complete(dio, bio); | |
536 | if (ret == 0) | |
537 | ret = ret2; | |
538 | } | |
539 | dio->reap_counter = 0; | |
540 | } | |
541 | return ret; | |
542 | } | |
543 | ||
544 | /* | |
545 | * Call into the fs to map some more disk blocks. We record the current number | |
546 | * of available blocks at dio->blocks_available. These are in units of the | |
547 | * fs blocksize, (1 << inode->i_blkbits). | |
548 | * | |
549 | * The fs is allowed to map lots of blocks at once. If it wants to do that, | |
550 | * it uses the passed inode-relative block number as the file offset, as usual. | |
551 | * | |
1d8fa7a2 | 552 | * get_block() is passed the number of i_blkbits-sized blocks which direct_io |
1da177e4 LT |
553 | * has remaining to do. The fs should not map more than this number of blocks. |
554 | * | |
555 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to | |
556 | * indicate how much contiguous disk space has been made available at | |
557 | * bh->b_blocknr. | |
558 | * | |
559 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). | |
560 | * This isn't very efficient... | |
561 | * | |
562 | * In the case of filesystem holes: the fs may return an arbitrarily-large | |
563 | * hole by returning an appropriate value in b_size and by clearing | |
564 | * buffer_mapped(). However the direct-io code will only process holes one | |
1d8fa7a2 | 565 | * block at a time - it will repeatedly call get_block() as it walks the hole. |
1da177e4 LT |
566 | */ |
567 | static int get_more_blocks(struct dio *dio) | |
568 | { | |
569 | int ret; | |
570 | struct buffer_head *map_bh = &dio->map_bh; | |
571 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ | |
572 | unsigned long fs_count; /* Number of filesystem-sized blocks */ | |
573 | unsigned long dio_count;/* Number of dio_block-sized blocks */ | |
574 | unsigned long blkmask; | |
575 | int create; | |
576 | ||
577 | /* | |
578 | * If there was a memory error and we've overwritten all the | |
579 | * mapped blocks then we can now return that memory error | |
580 | */ | |
581 | ret = dio->page_errors; | |
582 | if (ret == 0) { | |
1da177e4 LT |
583 | BUG_ON(dio->block_in_file >= dio->final_block_in_request); |
584 | fs_startblk = dio->block_in_file >> dio->blkfactor; | |
585 | dio_count = dio->final_block_in_request - dio->block_in_file; | |
586 | fs_count = dio_count >> dio->blkfactor; | |
587 | blkmask = (1 << dio->blkfactor) - 1; | |
588 | if (dio_count & blkmask) | |
589 | fs_count++; | |
590 | ||
3c674e74 NS |
591 | map_bh->b_state = 0; |
592 | map_bh->b_size = fs_count << dio->inode->i_blkbits; | |
593 | ||
5fe878ae CH |
594 | /* |
595 | * For writes inside i_size on a DIO_SKIP_HOLES filesystem we | |
596 | * forbid block creations: only overwrites are permitted. | |
597 | * We will return early to the caller once we see an | |
598 | * unmapped buffer head returned, and the caller will fall | |
599 | * back to buffered I/O. | |
600 | * | |
601 | * Otherwise the decision is left to the get_blocks method, | |
602 | * which may decide to handle it or also return an unmapped | |
603 | * buffer head. | |
604 | */ | |
b31dc66a | 605 | create = dio->rw & WRITE; |
5fe878ae | 606 | if (dio->flags & DIO_SKIP_HOLES) { |
1da177e4 LT |
607 | if (dio->block_in_file < (i_size_read(dio->inode) >> |
608 | dio->blkbits)) | |
609 | create = 0; | |
1da177e4 | 610 | } |
3c674e74 | 611 | |
1d8fa7a2 | 612 | ret = (*dio->get_block)(dio->inode, fs_startblk, |
1da177e4 LT |
613 | map_bh, create); |
614 | } | |
615 | return ret; | |
616 | } | |
617 | ||
618 | /* | |
619 | * There is no bio. Make one now. | |
620 | */ | |
621 | static int dio_new_bio(struct dio *dio, sector_t start_sector) | |
622 | { | |
623 | sector_t sector; | |
624 | int ret, nr_pages; | |
625 | ||
626 | ret = dio_bio_reap(dio); | |
627 | if (ret) | |
628 | goto out; | |
629 | sector = start_sector << (dio->blkbits - 9); | |
630 | nr_pages = min(dio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev)); | |
20d9600c | 631 | nr_pages = min(nr_pages, BIO_MAX_PAGES); |
1da177e4 | 632 | BUG_ON(nr_pages <= 0); |
20d9600c | 633 | dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages); |
1da177e4 LT |
634 | dio->boundary = 0; |
635 | out: | |
636 | return ret; | |
637 | } | |
638 | ||
639 | /* | |
640 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If | |
641 | * that was successful then update final_block_in_bio and take a ref against | |
642 | * the just-added page. | |
643 | * | |
644 | * Return zero on success. Non-zero means the caller needs to start a new BIO. | |
645 | */ | |
646 | static int dio_bio_add_page(struct dio *dio) | |
647 | { | |
648 | int ret; | |
649 | ||
650 | ret = bio_add_page(dio->bio, dio->cur_page, | |
651 | dio->cur_page_len, dio->cur_page_offset); | |
652 | if (ret == dio->cur_page_len) { | |
653 | /* | |
654 | * Decrement count only, if we are done with this page | |
655 | */ | |
656 | if ((dio->cur_page_len + dio->cur_page_offset) == PAGE_SIZE) | |
657 | dio->pages_in_io--; | |
658 | page_cache_get(dio->cur_page); | |
659 | dio->final_block_in_bio = dio->cur_page_block + | |
660 | (dio->cur_page_len >> dio->blkbits); | |
661 | ret = 0; | |
662 | } else { | |
663 | ret = 1; | |
664 | } | |
665 | return ret; | |
666 | } | |
667 | ||
668 | /* | |
669 | * Put cur_page under IO. The section of cur_page which is described by | |
670 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page | |
671 | * starts on-disk at cur_page_block. | |
672 | * | |
673 | * We take a ref against the page here (on behalf of its presence in the bio). | |
674 | * | |
675 | * The caller of this function is responsible for removing cur_page from the | |
676 | * dio, and for dropping the refcount which came from that presence. | |
677 | */ | |
678 | static int dio_send_cur_page(struct dio *dio) | |
679 | { | |
680 | int ret = 0; | |
681 | ||
682 | if (dio->bio) { | |
7a801ac6 | 683 | loff_t cur_offset = dio->cur_page_fs_offset; |
c2c6ca41 JB |
684 | loff_t bio_next_offset = dio->logical_offset_in_bio + |
685 | dio->bio->bi_size; | |
686 | ||
1da177e4 | 687 | /* |
c2c6ca41 JB |
688 | * See whether this new request is contiguous with the old. |
689 | * | |
f0940cee NK |
690 | * Btrfs cannot handle having logically non-contiguous requests |
691 | * submitted. For example if you have | |
c2c6ca41 JB |
692 | * |
693 | * Logical: [0-4095][HOLE][8192-12287] | |
f0940cee | 694 | * Physical: [0-4095] [4096-8191] |
c2c6ca41 JB |
695 | * |
696 | * We cannot submit those pages together as one BIO. So if our | |
697 | * current logical offset in the file does not equal what would | |
698 | * be the next logical offset in the bio, submit the bio we | |
699 | * have. | |
1da177e4 | 700 | */ |
c2c6ca41 JB |
701 | if (dio->final_block_in_bio != dio->cur_page_block || |
702 | cur_offset != bio_next_offset) | |
1da177e4 LT |
703 | dio_bio_submit(dio); |
704 | /* | |
705 | * Submit now if the underlying fs is about to perform a | |
706 | * metadata read | |
707 | */ | |
7a801ac6 | 708 | else if (dio->boundary) |
1da177e4 LT |
709 | dio_bio_submit(dio); |
710 | } | |
711 | ||
712 | if (dio->bio == NULL) { | |
713 | ret = dio_new_bio(dio, dio->cur_page_block); | |
714 | if (ret) | |
715 | goto out; | |
716 | } | |
717 | ||
718 | if (dio_bio_add_page(dio) != 0) { | |
719 | dio_bio_submit(dio); | |
720 | ret = dio_new_bio(dio, dio->cur_page_block); | |
721 | if (ret == 0) { | |
722 | ret = dio_bio_add_page(dio); | |
723 | BUG_ON(ret != 0); | |
724 | } | |
725 | } | |
726 | out: | |
727 | return ret; | |
728 | } | |
729 | ||
730 | /* | |
731 | * An autonomous function to put a chunk of a page under deferred IO. | |
732 | * | |
733 | * The caller doesn't actually know (or care) whether this piece of page is in | |
734 | * a BIO, or is under IO or whatever. We just take care of all possible | |
735 | * situations here. The separation between the logic of do_direct_IO() and | |
736 | * that of submit_page_section() is important for clarity. Please don't break. | |
737 | * | |
738 | * The chunk of page starts on-disk at blocknr. | |
739 | * | |
740 | * We perform deferred IO, by recording the last-submitted page inside our | |
741 | * private part of the dio structure. If possible, we just expand the IO | |
742 | * across that page here. | |
743 | * | |
744 | * If that doesn't work out then we put the old page into the bio and add this | |
745 | * page to the dio instead. | |
746 | */ | |
747 | static int | |
748 | submit_page_section(struct dio *dio, struct page *page, | |
749 | unsigned offset, unsigned len, sector_t blocknr) | |
750 | { | |
751 | int ret = 0; | |
752 | ||
98c4d57d AM |
753 | if (dio->rw & WRITE) { |
754 | /* | |
755 | * Read accounting is performed in submit_bio() | |
756 | */ | |
757 | task_io_account_write(len); | |
758 | } | |
759 | ||
1da177e4 LT |
760 | /* |
761 | * Can we just grow the current page's presence in the dio? | |
762 | */ | |
763 | if ( (dio->cur_page == page) && | |
764 | (dio->cur_page_offset + dio->cur_page_len == offset) && | |
765 | (dio->cur_page_block + | |
766 | (dio->cur_page_len >> dio->blkbits) == blocknr)) { | |
767 | dio->cur_page_len += len; | |
768 | ||
769 | /* | |
770 | * If dio->boundary then we want to schedule the IO now to | |
771 | * avoid metadata seeks. | |
772 | */ | |
773 | if (dio->boundary) { | |
774 | ret = dio_send_cur_page(dio); | |
775 | page_cache_release(dio->cur_page); | |
776 | dio->cur_page = NULL; | |
777 | } | |
778 | goto out; | |
779 | } | |
780 | ||
781 | /* | |
782 | * If there's a deferred page already there then send it. | |
783 | */ | |
784 | if (dio->cur_page) { | |
785 | ret = dio_send_cur_page(dio); | |
786 | page_cache_release(dio->cur_page); | |
787 | dio->cur_page = NULL; | |
788 | if (ret) | |
789 | goto out; | |
790 | } | |
791 | ||
792 | page_cache_get(page); /* It is in dio */ | |
793 | dio->cur_page = page; | |
794 | dio->cur_page_offset = offset; | |
795 | dio->cur_page_len = len; | |
796 | dio->cur_page_block = blocknr; | |
facd07b0 | 797 | dio->cur_page_fs_offset = dio->block_in_file << dio->blkbits; |
1da177e4 LT |
798 | out: |
799 | return ret; | |
800 | } | |
801 | ||
802 | /* | |
803 | * Clean any dirty buffers in the blockdev mapping which alias newly-created | |
804 | * file blocks. Only called for S_ISREG files - blockdevs do not set | |
805 | * buffer_new | |
806 | */ | |
807 | static void clean_blockdev_aliases(struct dio *dio) | |
808 | { | |
809 | unsigned i; | |
810 | unsigned nblocks; | |
811 | ||
812 | nblocks = dio->map_bh.b_size >> dio->inode->i_blkbits; | |
813 | ||
814 | for (i = 0; i < nblocks; i++) { | |
815 | unmap_underlying_metadata(dio->map_bh.b_bdev, | |
816 | dio->map_bh.b_blocknr + i); | |
817 | } | |
818 | } | |
819 | ||
820 | /* | |
821 | * If we are not writing the entire block and get_block() allocated | |
822 | * the block for us, we need to fill-in the unused portion of the | |
823 | * block with zeros. This happens only if user-buffer, fileoffset or | |
824 | * io length is not filesystem block-size multiple. | |
825 | * | |
826 | * `end' is zero if we're doing the start of the IO, 1 at the end of the | |
827 | * IO. | |
828 | */ | |
829 | static void dio_zero_block(struct dio *dio, int end) | |
830 | { | |
831 | unsigned dio_blocks_per_fs_block; | |
832 | unsigned this_chunk_blocks; /* In dio_blocks */ | |
833 | unsigned this_chunk_bytes; | |
834 | struct page *page; | |
835 | ||
836 | dio->start_zero_done = 1; | |
837 | if (!dio->blkfactor || !buffer_new(&dio->map_bh)) | |
838 | return; | |
839 | ||
840 | dio_blocks_per_fs_block = 1 << dio->blkfactor; | |
841 | this_chunk_blocks = dio->block_in_file & (dio_blocks_per_fs_block - 1); | |
842 | ||
843 | if (!this_chunk_blocks) | |
844 | return; | |
845 | ||
846 | /* | |
847 | * We need to zero out part of an fs block. It is either at the | |
848 | * beginning or the end of the fs block. | |
849 | */ | |
850 | if (end) | |
851 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; | |
852 | ||
853 | this_chunk_bytes = this_chunk_blocks << dio->blkbits; | |
854 | ||
557ed1fa | 855 | page = ZERO_PAGE(0); |
1da177e4 LT |
856 | if (submit_page_section(dio, page, 0, this_chunk_bytes, |
857 | dio->next_block_for_io)) | |
858 | return; | |
859 | ||
860 | dio->next_block_for_io += this_chunk_blocks; | |
861 | } | |
862 | ||
863 | /* | |
864 | * Walk the user pages, and the file, mapping blocks to disk and generating | |
865 | * a sequence of (page,offset,len,block) mappings. These mappings are injected | |
866 | * into submit_page_section(), which takes care of the next stage of submission | |
867 | * | |
868 | * Direct IO against a blockdev is different from a file. Because we can | |
869 | * happily perform page-sized but 512-byte aligned IOs. It is important that | |
870 | * blockdev IO be able to have fine alignment and large sizes. | |
871 | * | |
1d8fa7a2 | 872 | * So what we do is to permit the ->get_block function to populate bh.b_size |
1da177e4 LT |
873 | * with the size of IO which is permitted at this offset and this i_blkbits. |
874 | * | |
875 | * For best results, the blockdev should be set up with 512-byte i_blkbits and | |
1d8fa7a2 | 876 | * it should set b_size to PAGE_SIZE or more inside get_block(). This gives |
1da177e4 LT |
877 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
878 | */ | |
879 | static int do_direct_IO(struct dio *dio) | |
880 | { | |
881 | const unsigned blkbits = dio->blkbits; | |
882 | const unsigned blocks_per_page = PAGE_SIZE >> blkbits; | |
883 | struct page *page; | |
884 | unsigned block_in_page; | |
885 | struct buffer_head *map_bh = &dio->map_bh; | |
886 | int ret = 0; | |
887 | ||
888 | /* The I/O can start at any block offset within the first page */ | |
889 | block_in_page = dio->first_block_in_page; | |
890 | ||
891 | while (dio->block_in_file < dio->final_block_in_request) { | |
892 | page = dio_get_page(dio); | |
893 | if (IS_ERR(page)) { | |
894 | ret = PTR_ERR(page); | |
895 | goto out; | |
896 | } | |
897 | ||
898 | while (block_in_page < blocks_per_page) { | |
899 | unsigned offset_in_page = block_in_page << blkbits; | |
900 | unsigned this_chunk_bytes; /* # of bytes mapped */ | |
901 | unsigned this_chunk_blocks; /* # of blocks */ | |
902 | unsigned u; | |
903 | ||
904 | if (dio->blocks_available == 0) { | |
905 | /* | |
906 | * Need to go and map some more disk | |
907 | */ | |
908 | unsigned long blkmask; | |
909 | unsigned long dio_remainder; | |
910 | ||
911 | ret = get_more_blocks(dio); | |
912 | if (ret) { | |
913 | page_cache_release(page); | |
914 | goto out; | |
915 | } | |
916 | if (!buffer_mapped(map_bh)) | |
917 | goto do_holes; | |
918 | ||
919 | dio->blocks_available = | |
920 | map_bh->b_size >> dio->blkbits; | |
921 | dio->next_block_for_io = | |
922 | map_bh->b_blocknr << dio->blkfactor; | |
923 | if (buffer_new(map_bh)) | |
924 | clean_blockdev_aliases(dio); | |
925 | ||
926 | if (!dio->blkfactor) | |
927 | goto do_holes; | |
928 | ||
929 | blkmask = (1 << dio->blkfactor) - 1; | |
930 | dio_remainder = (dio->block_in_file & blkmask); | |
931 | ||
932 | /* | |
933 | * If we are at the start of IO and that IO | |
934 | * starts partway into a fs-block, | |
935 | * dio_remainder will be non-zero. If the IO | |
936 | * is a read then we can simply advance the IO | |
937 | * cursor to the first block which is to be | |
938 | * read. But if the IO is a write and the | |
939 | * block was newly allocated we cannot do that; | |
940 | * the start of the fs block must be zeroed out | |
941 | * on-disk | |
942 | */ | |
943 | if (!buffer_new(map_bh)) | |
944 | dio->next_block_for_io += dio_remainder; | |
945 | dio->blocks_available -= dio_remainder; | |
946 | } | |
947 | do_holes: | |
948 | /* Handle holes */ | |
949 | if (!buffer_mapped(map_bh)) { | |
35dc8161 | 950 | loff_t i_size_aligned; |
1da177e4 LT |
951 | |
952 | /* AKPM: eargh, -ENOTBLK is a hack */ | |
b31dc66a | 953 | if (dio->rw & WRITE) { |
1da177e4 LT |
954 | page_cache_release(page); |
955 | return -ENOTBLK; | |
956 | } | |
957 | ||
35dc8161 JM |
958 | /* |
959 | * Be sure to account for a partial block as the | |
960 | * last block in the file | |
961 | */ | |
962 | i_size_aligned = ALIGN(i_size_read(dio->inode), | |
963 | 1 << blkbits); | |
1da177e4 | 964 | if (dio->block_in_file >= |
35dc8161 | 965 | i_size_aligned >> blkbits) { |
1da177e4 LT |
966 | /* We hit eof */ |
967 | page_cache_release(page); | |
968 | goto out; | |
969 | } | |
eebd2aa3 CL |
970 | zero_user(page, block_in_page << blkbits, |
971 | 1 << blkbits); | |
1da177e4 LT |
972 | dio->block_in_file++; |
973 | block_in_page++; | |
974 | goto next_block; | |
975 | } | |
976 | ||
977 | /* | |
978 | * If we're performing IO which has an alignment which | |
979 | * is finer than the underlying fs, go check to see if | |
980 | * we must zero out the start of this block. | |
981 | */ | |
982 | if (unlikely(dio->blkfactor && !dio->start_zero_done)) | |
983 | dio_zero_block(dio, 0); | |
984 | ||
985 | /* | |
986 | * Work out, in this_chunk_blocks, how much disk we | |
987 | * can add to this page | |
988 | */ | |
989 | this_chunk_blocks = dio->blocks_available; | |
990 | u = (PAGE_SIZE - offset_in_page) >> blkbits; | |
991 | if (this_chunk_blocks > u) | |
992 | this_chunk_blocks = u; | |
993 | u = dio->final_block_in_request - dio->block_in_file; | |
994 | if (this_chunk_blocks > u) | |
995 | this_chunk_blocks = u; | |
996 | this_chunk_bytes = this_chunk_blocks << blkbits; | |
997 | BUG_ON(this_chunk_bytes == 0); | |
998 | ||
999 | dio->boundary = buffer_boundary(map_bh); | |
1000 | ret = submit_page_section(dio, page, offset_in_page, | |
1001 | this_chunk_bytes, dio->next_block_for_io); | |
1002 | if (ret) { | |
1003 | page_cache_release(page); | |
1004 | goto out; | |
1005 | } | |
1006 | dio->next_block_for_io += this_chunk_blocks; | |
1007 | ||
1008 | dio->block_in_file += this_chunk_blocks; | |
1009 | block_in_page += this_chunk_blocks; | |
1010 | dio->blocks_available -= this_chunk_blocks; | |
1011 | next_block: | |
d4569d2e | 1012 | BUG_ON(dio->block_in_file > dio->final_block_in_request); |
1da177e4 LT |
1013 | if (dio->block_in_file == dio->final_block_in_request) |
1014 | break; | |
1015 | } | |
1016 | ||
1017 | /* Drop the ref which was taken in get_user_pages() */ | |
1018 | page_cache_release(page); | |
1019 | block_in_page = 0; | |
1020 | } | |
1021 | out: | |
1022 | return ret; | |
1023 | } | |
1024 | ||
1da177e4 LT |
1025 | static ssize_t |
1026 | direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, | |
1027 | const struct iovec *iov, loff_t offset, unsigned long nr_segs, | |
1d8fa7a2 | 1028 | unsigned blkbits, get_block_t get_block, dio_iodone_t end_io, |
facd07b0 | 1029 | dio_submit_t submit_io, struct dio *dio) |
1da177e4 LT |
1030 | { |
1031 | unsigned long user_addr; | |
5eb6c7a2 | 1032 | unsigned long flags; |
1da177e4 LT |
1033 | int seg; |
1034 | ssize_t ret = 0; | |
1035 | ssize_t ret2; | |
1036 | size_t bytes; | |
1037 | ||
1da177e4 LT |
1038 | dio->inode = inode; |
1039 | dio->rw = rw; | |
1040 | dio->blkbits = blkbits; | |
1041 | dio->blkfactor = inode->i_blkbits - blkbits; | |
1da177e4 | 1042 | dio->block_in_file = offset >> blkbits; |
1da177e4 | 1043 | |
1d8fa7a2 | 1044 | dio->get_block = get_block; |
1da177e4 | 1045 | dio->end_io = end_io; |
facd07b0 | 1046 | dio->submit_io = submit_io; |
1da177e4 LT |
1047 | dio->final_block_in_bio = -1; |
1048 | dio->next_block_for_io = -1; | |
1049 | ||
1da177e4 | 1050 | dio->iocb = iocb; |
29504ff3 | 1051 | dio->i_size = i_size_read(inode); |
1da177e4 | 1052 | |
1da177e4 | 1053 | spin_lock_init(&dio->bio_lock); |
5eb6c7a2 | 1054 | dio->refcount = 1; |
1da177e4 LT |
1055 | |
1056 | /* | |
1057 | * In case of non-aligned buffers, we may need 2 more | |
1058 | * pages since we need to zero out first and last block. | |
1059 | */ | |
1060 | if (unlikely(dio->blkfactor)) | |
1061 | dio->pages_in_io = 2; | |
1da177e4 LT |
1062 | |
1063 | for (seg = 0; seg < nr_segs; seg++) { | |
1064 | user_addr = (unsigned long)iov[seg].iov_base; | |
1065 | dio->pages_in_io += | |
1066 | ((user_addr+iov[seg].iov_len +PAGE_SIZE-1)/PAGE_SIZE | |
1067 | - user_addr/PAGE_SIZE); | |
1068 | } | |
1069 | ||
1070 | for (seg = 0; seg < nr_segs; seg++) { | |
1071 | user_addr = (unsigned long)iov[seg].iov_base; | |
1072 | dio->size += bytes = iov[seg].iov_len; | |
1073 | ||
1074 | /* Index into the first page of the first block */ | |
1075 | dio->first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits; | |
1076 | dio->final_block_in_request = dio->block_in_file + | |
1077 | (bytes >> blkbits); | |
1078 | /* Page fetching state */ | |
1079 | dio->head = 0; | |
1080 | dio->tail = 0; | |
1081 | dio->curr_page = 0; | |
1082 | ||
1083 | dio->total_pages = 0; | |
1084 | if (user_addr & (PAGE_SIZE-1)) { | |
1085 | dio->total_pages++; | |
1086 | bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1)); | |
1087 | } | |
1088 | dio->total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE; | |
1089 | dio->curr_user_address = user_addr; | |
1090 | ||
1091 | ret = do_direct_IO(dio); | |
1092 | ||
1093 | dio->result += iov[seg].iov_len - | |
1094 | ((dio->final_block_in_request - dio->block_in_file) << | |
1095 | blkbits); | |
1096 | ||
1097 | if (ret) { | |
1098 | dio_cleanup(dio); | |
1099 | break; | |
1100 | } | |
1101 | } /* end iovec loop */ | |
1102 | ||
facd07b0 | 1103 | if (ret == -ENOTBLK) { |
1da177e4 LT |
1104 | /* |
1105 | * The remaining part of the request will be | |
1106 | * be handled by buffered I/O when we return | |
1107 | */ | |
1108 | ret = 0; | |
1109 | } | |
1110 | /* | |
1111 | * There may be some unwritten disk at the end of a part-written | |
1112 | * fs-block-sized block. Go zero that now. | |
1113 | */ | |
1114 | dio_zero_block(dio, 1); | |
1115 | ||
1116 | if (dio->cur_page) { | |
1117 | ret2 = dio_send_cur_page(dio); | |
1118 | if (ret == 0) | |
1119 | ret = ret2; | |
1120 | page_cache_release(dio->cur_page); | |
1121 | dio->cur_page = NULL; | |
1122 | } | |
1123 | if (dio->bio) | |
1124 | dio_bio_submit(dio); | |
1125 | ||
1126 | /* | |
1127 | * It is possible that, we return short IO due to end of file. | |
1128 | * In that case, we need to release all the pages we got hold on. | |
1129 | */ | |
1130 | dio_cleanup(dio); | |
1131 | ||
1132 | /* | |
1133 | * All block lookups have been performed. For READ requests | |
1b1dcc1b | 1134 | * we can let i_mutex go now that its achieved its purpose |
1da177e4 LT |
1135 | * of protecting us from looking up uninitialized blocks. |
1136 | */ | |
5fe878ae | 1137 | if (rw == READ && (dio->flags & DIO_LOCKING)) |
1b1dcc1b | 1138 | mutex_unlock(&dio->inode->i_mutex); |
1da177e4 LT |
1139 | |
1140 | /* | |
8459d86a ZB |
1141 | * The only time we want to leave bios in flight is when a successful |
1142 | * partial aio read or full aio write have been setup. In that case | |
1143 | * bio completion will call aio_complete. The only time it's safe to | |
1144 | * call aio_complete is when we return -EIOCBQUEUED, so we key on that. | |
1145 | * This had *better* be the only place that raises -EIOCBQUEUED. | |
1da177e4 | 1146 | */ |
8459d86a ZB |
1147 | BUG_ON(ret == -EIOCBQUEUED); |
1148 | if (dio->is_async && ret == 0 && dio->result && | |
1149 | ((rw & READ) || (dio->result == dio->size))) | |
1150 | ret = -EIOCBQUEUED; | |
0273201e | 1151 | |
7eaceacc | 1152 | if (ret != -EIOCBQUEUED) |
6d544bb4 | 1153 | dio_await_completion(dio); |
1da177e4 | 1154 | |
8459d86a ZB |
1155 | /* |
1156 | * Sync will always be dropping the final ref and completing the | |
5eb6c7a2 ZB |
1157 | * operation. AIO can if it was a broken operation described above or |
1158 | * in fact if all the bios race to complete before we get here. In | |
1159 | * that case dio_complete() translates the EIOCBQUEUED into the proper | |
1160 | * return code that the caller will hand to aio_complete(). | |
1161 | * | |
1162 | * This is managed by the bio_lock instead of being an atomic_t so that | |
1163 | * completion paths can drop their ref and use the remaining count to | |
1164 | * decide to wake the submission path atomically. | |
8459d86a | 1165 | */ |
5eb6c7a2 ZB |
1166 | spin_lock_irqsave(&dio->bio_lock, flags); |
1167 | ret2 = --dio->refcount; | |
1168 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
fcb82f88 | 1169 | |
5eb6c7a2 | 1170 | if (ret2 == 0) { |
40e2e973 | 1171 | ret = dio_complete(dio, offset, ret, false); |
8459d86a ZB |
1172 | kfree(dio); |
1173 | } else | |
1174 | BUG_ON(ret != -EIOCBQUEUED); | |
1da177e4 | 1175 | |
1da177e4 LT |
1176 | return ret; |
1177 | } | |
1178 | ||
eafdc7d1 CH |
1179 | /* |
1180 | * This is a library function for use by filesystem drivers. | |
1181 | * | |
1182 | * The locking rules are governed by the flags parameter: | |
1183 | * - if the flags value contains DIO_LOCKING we use a fancy locking | |
1184 | * scheme for dumb filesystems. | |
1185 | * For writes this function is called under i_mutex and returns with | |
1186 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | |
1187 | * taken and dropped again before returning. | |
eafdc7d1 CH |
1188 | * - if the flags value does NOT contain DIO_LOCKING we don't use any |
1189 | * internal locking but rather rely on the filesystem to synchronize | |
1190 | * direct I/O reads/writes versus each other and truncate. | |
df2d6f26 CH |
1191 | * |
1192 | * To help with locking against truncate we incremented the i_dio_count | |
1193 | * counter before starting direct I/O, and decrement it once we are done. | |
1194 | * Truncate can wait for it to reach zero to provide exclusion. It is | |
1195 | * expected that filesystem provide exclusion between new direct I/O | |
1196 | * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, | |
1197 | * but other filesystems need to take care of this on their own. | |
eafdc7d1 | 1198 | */ |
1da177e4 | 1199 | ssize_t |
eafdc7d1 | 1200 | __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, |
1da177e4 | 1201 | struct block_device *bdev, const struct iovec *iov, loff_t offset, |
1d8fa7a2 | 1202 | unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, |
facd07b0 | 1203 | dio_submit_t submit_io, int flags) |
1da177e4 LT |
1204 | { |
1205 | int seg; | |
1206 | size_t size; | |
1207 | unsigned long addr; | |
1208 | unsigned blkbits = inode->i_blkbits; | |
1209 | unsigned bdev_blkbits = 0; | |
1210 | unsigned blocksize_mask = (1 << blkbits) - 1; | |
1211 | ssize_t retval = -EINVAL; | |
1212 | loff_t end = offset; | |
1213 | struct dio *dio; | |
1da177e4 LT |
1214 | |
1215 | if (rw & WRITE) | |
721a9602 | 1216 | rw = WRITE_ODIRECT; |
1da177e4 LT |
1217 | |
1218 | if (bdev) | |
e1defc4f | 1219 | bdev_blkbits = blksize_bits(bdev_logical_block_size(bdev)); |
1da177e4 LT |
1220 | |
1221 | if (offset & blocksize_mask) { | |
1222 | if (bdev) | |
1223 | blkbits = bdev_blkbits; | |
1224 | blocksize_mask = (1 << blkbits) - 1; | |
1225 | if (offset & blocksize_mask) | |
1226 | goto out; | |
1227 | } | |
1228 | ||
1229 | /* Check the memory alignment. Blocks cannot straddle pages */ | |
1230 | for (seg = 0; seg < nr_segs; seg++) { | |
1231 | addr = (unsigned long)iov[seg].iov_base; | |
1232 | size = iov[seg].iov_len; | |
1233 | end += size; | |
1234 | if ((addr & blocksize_mask) || (size & blocksize_mask)) { | |
1235 | if (bdev) | |
1236 | blkbits = bdev_blkbits; | |
1237 | blocksize_mask = (1 << blkbits) - 1; | |
1238 | if ((addr & blocksize_mask) || (size & blocksize_mask)) | |
1239 | goto out; | |
1240 | } | |
1241 | } | |
1242 | ||
f9b5570d CH |
1243 | /* watch out for a 0 len io from a tricksy fs */ |
1244 | if (rw == READ && end == offset) | |
1245 | return 0; | |
1246 | ||
23aee091 | 1247 | dio = kmalloc(sizeof(*dio), GFP_KERNEL); |
1da177e4 LT |
1248 | retval = -ENOMEM; |
1249 | if (!dio) | |
1250 | goto out; | |
23aee091 JM |
1251 | /* |
1252 | * Believe it or not, zeroing out the page array caused a .5% | |
1253 | * performance regression in a database benchmark. So, we take | |
1254 | * care to only zero out what's needed. | |
1255 | */ | |
1256 | memset(dio, 0, offsetof(struct dio, pages)); | |
1da177e4 | 1257 | |
5fe878ae CH |
1258 | dio->flags = flags; |
1259 | if (dio->flags & DIO_LOCKING) { | |
f9b5570d | 1260 | if (rw == READ) { |
5fe878ae CH |
1261 | struct address_space *mapping = |
1262 | iocb->ki_filp->f_mapping; | |
1da177e4 | 1263 | |
5fe878ae CH |
1264 | /* will be released by direct_io_worker */ |
1265 | mutex_lock(&inode->i_mutex); | |
1da177e4 LT |
1266 | |
1267 | retval = filemap_write_and_wait_range(mapping, offset, | |
1268 | end - 1); | |
1269 | if (retval) { | |
5fe878ae | 1270 | mutex_unlock(&inode->i_mutex); |
1da177e4 LT |
1271 | kfree(dio); |
1272 | goto out; | |
1273 | } | |
1da177e4 | 1274 | } |
1da177e4 LT |
1275 | } |
1276 | ||
df2d6f26 CH |
1277 | /* |
1278 | * Will be decremented at I/O completion time. | |
1279 | */ | |
1280 | atomic_inc(&inode->i_dio_count); | |
1281 | ||
1da177e4 LT |
1282 | /* |
1283 | * For file extending writes updating i_size before data | |
1284 | * writeouts complete can expose uninitialized blocks. So | |
1285 | * even for AIO, we need to wait for i/o to complete before | |
1286 | * returning in this case. | |
1287 | */ | |
b31dc66a | 1288 | dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) && |
1da177e4 LT |
1289 | (end > i_size_read(inode))); |
1290 | ||
1291 | retval = direct_io_worker(rw, iocb, inode, iov, offset, | |
facd07b0 JB |
1292 | nr_segs, blkbits, get_block, end_io, |
1293 | submit_io, dio); | |
1da177e4 | 1294 | |
7bb46a67 | 1295 | out: |
1296 | return retval; | |
1297 | } | |
1da177e4 | 1298 | EXPORT_SYMBOL(__blockdev_direct_IO); |