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1 | /* |
2 | * fs/direct-io.c |
3 | * |
4 | * Copyright (C) 2002, Linus Torvalds. |
5 | * |
6 | * O_DIRECT |
7 | * |
8 | * 04Jul2002 Andrew Morton |
9 | * Initial version |
10 | * 11Sep2002 janetinc@us.ibm.com |
11 | * added readv/writev support. |
12 | * 29Oct2002 Andrew Morton |
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> |
30 | #include <linux/task_io_accounting_ops.h> |
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. |
56 | */ |
57 | |
58 | struct dio { |
59 | /* BIO submission state */ |
60 | struct bio *bio; /* bio under assembly */ |
61 | struct inode *inode; |
62 | int rw; |
63 | loff_t i_size; /* i_size when submitted */ |
64 | int flags; /* doesn't change */ |
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 */ |
83 | get_block_t *get_block; /* block mapping function */ |
84 | dio_iodone_t *end_io; /* IO completion function */ |
85 | dio_submit_t *submit_io; /* IO submition function */ |
86 | loff_t logical_offset_in_bio; /* current first logical block in bio */ |
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 */ |
90 | struct buffer_head map_bh; /* last get_block() result */ |
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 */ |
101 | loff_t cur_page_fs_offset; /* Offset in file */ |
102 | |
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 | |
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 | */ |
126 | unsigned head; /* next page to process */ |
127 | unsigned tail; /* last valid page + 1 */ |
128 | int page_errors; /* errno from get_user_pages() */ |
129 | |
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 */ |
136 | }; |
137 | |
138 | /* |
139 | * How many pages are in the queue? |
140 | */ |
141 | static inline unsigned dio_pages_present(struct dio *dio) |
142 | { |
143 | return dio->tail - dio->head; |
144 | } |
145 | |
146 | /* |
147 | * Go grab and pin some userspace pages. Typically we'll get 64 at a time. |
148 | */ |
149 | static int dio_refill_pages(struct dio *dio) |
150 | { |
151 | int ret; |
152 | int nr_pages; |
153 | |
154 | nr_pages = min(dio->total_pages - dio->curr_page, DIO_PAGES); |
155 | ret = get_user_pages_fast( |
156 | dio->curr_user_address, /* Where from? */ |
157 | nr_pages, /* How many pages? */ |
158 | dio->rw == READ, /* Write to memory? */ |
159 | &dio->pages[0]); /* Put results here */ |
160 | |
161 | if (ret < 0 && dio->blocks_available && (dio->rw & WRITE)) { |
162 | struct page *page = ZERO_PAGE(0); |
163 | /* |
164 | * A memory fault, but the filesystem has some outstanding |
165 | * mapped blocks. We need to use those blocks up to avoid |
166 | * leaking stale data in the file. |
167 | */ |
168 | if (dio->page_errors == 0) |
169 | dio->page_errors = ret; |
170 | page_cache_get(page); |
171 | dio->pages[0] = page; |
172 | dio->head = 0; |
173 | dio->tail = 1; |
174 | ret = 0; |
175 | goto out; |
176 | } |
177 | |
178 | if (ret >= 0) { |
179 | dio->curr_user_address += ret * PAGE_SIZE; |
180 | dio->curr_page += ret; |
181 | dio->head = 0; |
182 | dio->tail = ret; |
183 | ret = 0; |
184 | } |
185 | out: |
186 | return ret; |
187 | } |
188 | |
189 | /* |
190 | * Get another userspace page. Returns an ERR_PTR on error. Pages are |
191 | * buffered inside the dio so that we can call get_user_pages() against a |
192 | * decent number of pages, less frequently. To provide nicer use of the |
193 | * L1 cache. |
194 | */ |
195 | static struct page *dio_get_page(struct dio *dio) |
196 | { |
197 | if (dio_pages_present(dio) == 0) { |
198 | int ret; |
199 | |
200 | ret = dio_refill_pages(dio); |
201 | if (ret) |
202 | return ERR_PTR(ret); |
203 | BUG_ON(dio_pages_present(dio) == 0); |
204 | } |
205 | return dio->pages[dio->head++]; |
206 | } |
207 | |
208 | /** |
209 | * dio_complete() - called when all DIO BIO I/O has been completed |
210 | * @offset: the byte offset in the file of the completed operation |
211 | * |
212 | * This releases locks as dictated by the locking type, lets interested parties |
213 | * know that a DIO operation has completed, and calculates the resulting return |
214 | * code for the operation. |
215 | * |
216 | * It lets the filesystem know if it registered an interest earlier via |
217 | * get_block. Pass the private field of the map buffer_head so that |
218 | * filesystems can use it to hold additional state between get_block calls and |
219 | * dio_complete. |
220 | */ |
221 | static ssize_t dio_complete(struct dio *dio, loff_t offset, ssize_t ret, bool is_async) |
222 | { |
223 | ssize_t transferred = 0; |
224 | |
225 | /* |
226 | * AIO submission can race with bio completion to get here while |
227 | * expecting to have the last io completed by bio completion. |
228 | * In that case -EIOCBQUEUED is in fact not an error we want |
229 | * to preserve through this call. |
230 | */ |
231 | if (ret == -EIOCBQUEUED) |
232 | ret = 0; |
233 | |
234 | if (dio->result) { |
235 | transferred = dio->result; |
236 | |
237 | /* Check for short read case */ |
238 | if ((dio->rw == READ) && ((offset + transferred) > dio->i_size)) |
239 | transferred = dio->i_size - offset; |
240 | } |
241 | |
242 | if (ret == 0) |
243 | ret = dio->page_errors; |
244 | if (ret == 0) |
245 | ret = dio->io_error; |
246 | if (ret == 0) |
247 | ret = transferred; |
248 | |
249 | if (dio->end_io && dio->result) { |
250 | dio->end_io(dio->iocb, offset, transferred, |
251 | dio->map_bh.b_private, ret, is_async); |
252 | } else if (is_async) { |
253 | aio_complete(dio->iocb, ret, 0); |
254 | } |
255 | |
256 | if (dio->flags & DIO_LOCKING) |
257 | /* lockdep: non-owner release */ |
258 | up_read_non_owner(&dio->inode->i_alloc_sem); |
259 | |
260 | return ret; |
261 | } |
262 | |
263 | static int dio_bio_complete(struct dio *dio, struct bio *bio); |
264 | /* |
265 | * Asynchronous IO callback. |
266 | */ |
267 | static void dio_bio_end_aio(struct bio *bio, int error) |
268 | { |
269 | struct dio *dio = bio->bi_private; |
270 | unsigned long remaining; |
271 | unsigned long flags; |
272 | |
273 | /* cleanup the bio */ |
274 | dio_bio_complete(dio, bio); |
275 | |
276 | spin_lock_irqsave(&dio->bio_lock, flags); |
277 | remaining = --dio->refcount; |
278 | if (remaining == 1 && dio->waiter) |
279 | wake_up_process(dio->waiter); |
280 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
281 | |
282 | if (remaining == 0) { |
283 | dio_complete(dio, dio->iocb->ki_pos, 0, true); |
284 | kfree(dio); |
285 | } |
286 | } |
287 | |
288 | /* |
289 | * The BIO completion handler simply queues the BIO up for the process-context |
290 | * handler. |
291 | * |
292 | * During I/O bi_private points at the dio. After I/O, bi_private is used to |
293 | * implement a singly-linked list of completed BIOs, at dio->bio_list. |
294 | */ |
295 | static void dio_bio_end_io(struct bio *bio, int error) |
296 | { |
297 | struct dio *dio = bio->bi_private; |
298 | unsigned long flags; |
299 | |
300 | spin_lock_irqsave(&dio->bio_lock, flags); |
301 | bio->bi_private = dio->bio_list; |
302 | dio->bio_list = bio; |
303 | if (--dio->refcount == 1 && dio->waiter) |
304 | wake_up_process(dio->waiter); |
305 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
306 | } |
307 | |
308 | /** |
309 | * dio_end_io - handle the end io action for the given bio |
310 | * @bio: The direct io bio thats being completed |
311 | * @error: Error if there was one |
312 | * |
313 | * This is meant to be called by any filesystem that uses their own dio_submit_t |
314 | * so that the DIO specific endio actions are dealt with after the filesystem |
315 | * has done it's completion work. |
316 | */ |
317 | void dio_end_io(struct bio *bio, int error) |
318 | { |
319 | struct dio *dio = bio->bi_private; |
320 | |
321 | if (dio->is_async) |
322 | dio_bio_end_aio(bio, error); |
323 | else |
324 | dio_bio_end_io(bio, error); |
325 | } |
326 | EXPORT_SYMBOL_GPL(dio_end_io); |
327 | |
328 | static void |
329 | dio_bio_alloc(struct dio *dio, struct block_device *bdev, |
330 | sector_t first_sector, int nr_vecs) |
331 | { |
332 | struct bio *bio; |
333 | |
334 | /* |
335 | * bio_alloc() is guaranteed to return a bio when called with |
336 | * __GFP_WAIT and we request a valid number of vectors. |
337 | */ |
338 | bio = bio_alloc(GFP_KERNEL, nr_vecs); |
339 | |
340 | bio->bi_bdev = bdev; |
341 | bio->bi_sector = first_sector; |
342 | if (dio->is_async) |
343 | bio->bi_end_io = dio_bio_end_aio; |
344 | else |
345 | bio->bi_end_io = dio_bio_end_io; |
346 | |
347 | dio->bio = bio; |
348 | dio->logical_offset_in_bio = dio->cur_page_fs_offset; |
349 | } |
350 | |
351 | /* |
352 | * In the AIO read case we speculatively dirty the pages before starting IO. |
353 | * During IO completion, any of these pages which happen to have been written |
354 | * back will be redirtied by bio_check_pages_dirty(). |
355 | * |
356 | * bios hold a dio reference between submit_bio and ->end_io. |
357 | */ |
358 | static void dio_bio_submit(struct dio *dio) |
359 | { |
360 | struct bio *bio = dio->bio; |
361 | unsigned long flags; |
362 | |
363 | bio->bi_private = dio; |
364 | |
365 | spin_lock_irqsave(&dio->bio_lock, flags); |
366 | dio->refcount++; |
367 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
368 | |
369 | if (dio->is_async && dio->rw == READ) |
370 | bio_set_pages_dirty(bio); |
371 | |
372 | if (dio->submit_io) |
373 | dio->submit_io(dio->rw, bio, dio->inode, |
374 | dio->logical_offset_in_bio); |
375 | else |
376 | submit_bio(dio->rw, bio); |
377 | |
378 | dio->bio = NULL; |
379 | dio->boundary = 0; |
380 | dio->logical_offset_in_bio = 0; |
381 | } |
382 | |
383 | /* |
384 | * Release any resources in case of a failure |
385 | */ |
386 | static void dio_cleanup(struct dio *dio) |
387 | { |
388 | while (dio_pages_present(dio)) |
389 | page_cache_release(dio_get_page(dio)); |
390 | } |
391 | |
392 | /* |
393 | * Wait for the next BIO to complete. Remove it and return it. NULL is |
394 | * returned once all BIOs have been completed. This must only be called once |
395 | * all bios have been issued so that dio->refcount can only decrease. This |
396 | * requires that that the caller hold a reference on the dio. |
397 | */ |
398 | static struct bio *dio_await_one(struct dio *dio) |
399 | { |
400 | unsigned long flags; |
401 | struct bio *bio = NULL; |
402 | |
403 | spin_lock_irqsave(&dio->bio_lock, flags); |
404 | |
405 | /* |
406 | * Wait as long as the list is empty and there are bios in flight. bio |
407 | * completion drops the count, maybe adds to the list, and wakes while |
408 | * holding the bio_lock so we don't need set_current_state()'s barrier |
409 | * and can call it after testing our condition. |
410 | */ |
411 | while (dio->refcount > 1 && dio->bio_list == NULL) { |
412 | __set_current_state(TASK_UNINTERRUPTIBLE); |
413 | dio->waiter = current; |
414 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
415 | io_schedule(); |
416 | /* wake up sets us TASK_RUNNING */ |
417 | spin_lock_irqsave(&dio->bio_lock, flags); |
418 | dio->waiter = NULL; |
419 | } |
420 | if (dio->bio_list) { |
421 | bio = dio->bio_list; |
422 | dio->bio_list = bio->bi_private; |
423 | } |
424 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
425 | return bio; |
426 | } |
427 | |
428 | /* |
429 | * Process one completed BIO. No locks are held. |
430 | */ |
431 | static int dio_bio_complete(struct dio *dio, struct bio *bio) |
432 | { |
433 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); |
434 | struct bio_vec *bvec = bio->bi_io_vec; |
435 | int page_no; |
436 | |
437 | if (!uptodate) |
438 | dio->io_error = -EIO; |
439 | |
440 | if (dio->is_async && dio->rw == READ) { |
441 | bio_check_pages_dirty(bio); /* transfers ownership */ |
442 | } else { |
443 | for (page_no = 0; page_no < bio->bi_vcnt; page_no++) { |
444 | struct page *page = bvec[page_no].bv_page; |
445 | |
446 | if (dio->rw == READ && !PageCompound(page)) |
447 | set_page_dirty_lock(page); |
448 | page_cache_release(page); |
449 | } |
450 | bio_put(bio); |
451 | } |
452 | return uptodate ? 0 : -EIO; |
453 | } |
454 | |
455 | /* |
456 | * Wait on and process all in-flight BIOs. This must only be called once |
457 | * all bios have been issued so that the refcount can only decrease. |
458 | * This just waits for all bios to make it through dio_bio_complete. IO |
459 | * errors are propagated through dio->io_error and should be propagated via |
460 | * dio_complete(). |
461 | */ |
462 | static void dio_await_completion(struct dio *dio) |
463 | { |
464 | struct bio *bio; |
465 | do { |
466 | bio = dio_await_one(dio); |
467 | if (bio) |
468 | dio_bio_complete(dio, bio); |
469 | } while (bio); |
470 | } |
471 | |
472 | /* |
473 | * A really large O_DIRECT read or write can generate a lot of BIOs. So |
474 | * to keep the memory consumption sane we periodically reap any completed BIOs |
475 | * during the BIO generation phase. |
476 | * |
477 | * This also helps to limit the peak amount of pinned userspace memory. |
478 | */ |
479 | static int dio_bio_reap(struct dio *dio) |
480 | { |
481 | int ret = 0; |
482 | |
483 | if (dio->reap_counter++ >= 64) { |
484 | while (dio->bio_list) { |
485 | unsigned long flags; |
486 | struct bio *bio; |
487 | int ret2; |
488 | |
489 | spin_lock_irqsave(&dio->bio_lock, flags); |
490 | bio = dio->bio_list; |
491 | dio->bio_list = bio->bi_private; |
492 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
493 | ret2 = dio_bio_complete(dio, bio); |
494 | if (ret == 0) |
495 | ret = ret2; |
496 | } |
497 | dio->reap_counter = 0; |
498 | } |
499 | return ret; |
500 | } |
501 | |
502 | /* |
503 | * Call into the fs to map some more disk blocks. We record the current number |
504 | * of available blocks at dio->blocks_available. These are in units of the |
505 | * fs blocksize, (1 << inode->i_blkbits). |
506 | * |
507 | * The fs is allowed to map lots of blocks at once. If it wants to do that, |
508 | * it uses the passed inode-relative block number as the file offset, as usual. |
509 | * |
510 | * get_block() is passed the number of i_blkbits-sized blocks which direct_io |
511 | * has remaining to do. The fs should not map more than this number of blocks. |
512 | * |
513 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to |
514 | * indicate how much contiguous disk space has been made available at |
515 | * bh->b_blocknr. |
516 | * |
517 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). |
518 | * This isn't very efficient... |
519 | * |
520 | * In the case of filesystem holes: the fs may return an arbitrarily-large |
521 | * hole by returning an appropriate value in b_size and by clearing |
522 | * buffer_mapped(). However the direct-io code will only process holes one |
523 | * block at a time - it will repeatedly call get_block() as it walks the hole. |
524 | */ |
525 | static int get_more_blocks(struct dio *dio) |
526 | { |
527 | int ret; |
528 | struct buffer_head *map_bh = &dio->map_bh; |
529 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ |
530 | unsigned long fs_count; /* Number of filesystem-sized blocks */ |
531 | unsigned long dio_count;/* Number of dio_block-sized blocks */ |
532 | unsigned long blkmask; |
533 | int create; |
534 | |
535 | /* |
536 | * If there was a memory error and we've overwritten all the |
537 | * mapped blocks then we can now return that memory error |
538 | */ |
539 | ret = dio->page_errors; |
540 | if (ret == 0) { |
541 | BUG_ON(dio->block_in_file >= dio->final_block_in_request); |
542 | fs_startblk = dio->block_in_file >> dio->blkfactor; |
543 | dio_count = dio->final_block_in_request - dio->block_in_file; |
544 | fs_count = dio_count >> dio->blkfactor; |
545 | blkmask = (1 << dio->blkfactor) - 1; |
546 | if (dio_count & blkmask) |
547 | fs_count++; |
548 | |
549 | map_bh->b_state = 0; |
550 | map_bh->b_size = fs_count << dio->inode->i_blkbits; |
551 | |
552 | /* |
553 | * For writes inside i_size on a DIO_SKIP_HOLES filesystem we |
554 | * forbid block creations: only overwrites are permitted. |
555 | * We will return early to the caller once we see an |
556 | * unmapped buffer head returned, and the caller will fall |
557 | * back to buffered I/O. |
558 | * |
559 | * Otherwise the decision is left to the get_blocks method, |
560 | * which may decide to handle it or also return an unmapped |
561 | * buffer head. |
562 | */ |
563 | create = dio->rw & WRITE; |
564 | if (dio->flags & DIO_SKIP_HOLES) { |
565 | if (dio->block_in_file < (i_size_read(dio->inode) >> |
566 | dio->blkbits)) |
567 | create = 0; |
568 | } |
569 | |
570 | ret = (*dio->get_block)(dio->inode, fs_startblk, |
571 | map_bh, create); |
572 | } |
573 | return ret; |
574 | } |
575 | |
576 | /* |
577 | * There is no bio. Make one now. |
578 | */ |
579 | static int dio_new_bio(struct dio *dio, sector_t start_sector) |
580 | { |
581 | sector_t sector; |
582 | int ret, nr_pages; |
583 | |
584 | ret = dio_bio_reap(dio); |
585 | if (ret) |
586 | goto out; |
587 | sector = start_sector << (dio->blkbits - 9); |
588 | nr_pages = min(dio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev)); |
589 | nr_pages = min(nr_pages, BIO_MAX_PAGES); |
590 | BUG_ON(nr_pages <= 0); |
591 | dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages); |
592 | dio->boundary = 0; |
593 | out: |
594 | return ret; |
595 | } |
596 | |
597 | /* |
598 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If |
599 | * that was successful then update final_block_in_bio and take a ref against |
600 | * the just-added page. |
601 | * |
602 | * Return zero on success. Non-zero means the caller needs to start a new BIO. |
603 | */ |
604 | static int dio_bio_add_page(struct dio *dio) |
605 | { |
606 | int ret; |
607 | |
608 | ret = bio_add_page(dio->bio, dio->cur_page, |
609 | dio->cur_page_len, dio->cur_page_offset); |
610 | if (ret == dio->cur_page_len) { |
611 | /* |
612 | * Decrement count only, if we are done with this page |
613 | */ |
614 | if ((dio->cur_page_len + dio->cur_page_offset) == PAGE_SIZE) |
615 | dio->pages_in_io--; |
616 | page_cache_get(dio->cur_page); |
617 | dio->final_block_in_bio = dio->cur_page_block + |
618 | (dio->cur_page_len >> dio->blkbits); |
619 | ret = 0; |
620 | } else { |
621 | ret = 1; |
622 | } |
623 | return ret; |
624 | } |
625 | |
626 | /* |
627 | * Put cur_page under IO. The section of cur_page which is described by |
628 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page |
629 | * starts on-disk at cur_page_block. |
630 | * |
631 | * We take a ref against the page here (on behalf of its presence in the bio). |
632 | * |
633 | * The caller of this function is responsible for removing cur_page from the |
634 | * dio, and for dropping the refcount which came from that presence. |
635 | */ |
636 | static int dio_send_cur_page(struct dio *dio) |
637 | { |
638 | int ret = 0; |
639 | |
640 | if (dio->bio) { |
641 | loff_t cur_offset = dio->cur_page_fs_offset; |
642 | loff_t bio_next_offset = dio->logical_offset_in_bio + |
643 | dio->bio->bi_size; |
644 | |
645 | /* |
646 | * See whether this new request is contiguous with the old. |
647 | * |
648 | * Btrfs cannot handl having logically non-contiguous requests |
649 | * submitted. For exmple if you have |
650 | * |
651 | * Logical: [0-4095][HOLE][8192-12287] |
652 | * Phyiscal: [0-4095] [4096-8181] |
653 | * |
654 | * We cannot submit those pages together as one BIO. So if our |
655 | * current logical offset in the file does not equal what would |
656 | * be the next logical offset in the bio, submit the bio we |
657 | * have. |
658 | */ |
659 | if (dio->final_block_in_bio != dio->cur_page_block || |
660 | cur_offset != bio_next_offset) |
661 | dio_bio_submit(dio); |
662 | /* |
663 | * Submit now if the underlying fs is about to perform a |
664 | * metadata read |
665 | */ |
666 | else if (dio->boundary) |
667 | dio_bio_submit(dio); |
668 | } |
669 | |
670 | if (dio->bio == NULL) { |
671 | ret = dio_new_bio(dio, dio->cur_page_block); |
672 | if (ret) |
673 | goto out; |
674 | } |
675 | |
676 | if (dio_bio_add_page(dio) != 0) { |
677 | dio_bio_submit(dio); |
678 | ret = dio_new_bio(dio, dio->cur_page_block); |
679 | if (ret == 0) { |
680 | ret = dio_bio_add_page(dio); |
681 | BUG_ON(ret != 0); |
682 | } |
683 | } |
684 | out: |
685 | return ret; |
686 | } |
687 | |
688 | /* |
689 | * An autonomous function to put a chunk of a page under deferred IO. |
690 | * |
691 | * The caller doesn't actually know (or care) whether this piece of page is in |
692 | * a BIO, or is under IO or whatever. We just take care of all possible |
693 | * situations here. The separation between the logic of do_direct_IO() and |
694 | * that of submit_page_section() is important for clarity. Please don't break. |
695 | * |
696 | * The chunk of page starts on-disk at blocknr. |
697 | * |
698 | * We perform deferred IO, by recording the last-submitted page inside our |
699 | * private part of the dio structure. If possible, we just expand the IO |
700 | * across that page here. |
701 | * |
702 | * If that doesn't work out then we put the old page into the bio and add this |
703 | * page to the dio instead. |
704 | */ |
705 | static int |
706 | submit_page_section(struct dio *dio, struct page *page, |
707 | unsigned offset, unsigned len, sector_t blocknr) |
708 | { |
709 | int ret = 0; |
710 | |
711 | if (dio->rw & WRITE) { |
712 | /* |
713 | * Read accounting is performed in submit_bio() |
714 | */ |
715 | task_io_account_write(len); |
716 | } |
717 | |
718 | /* |
719 | * Can we just grow the current page's presence in the dio? |
720 | */ |
721 | if ( (dio->cur_page == page) && |
722 | (dio->cur_page_offset + dio->cur_page_len == offset) && |
723 | (dio->cur_page_block + |
724 | (dio->cur_page_len >> dio->blkbits) == blocknr)) { |
725 | dio->cur_page_len += len; |
726 | |
727 | /* |
728 | * If dio->boundary then we want to schedule the IO now to |
729 | * avoid metadata seeks. |
730 | */ |
731 | if (dio->boundary) { |
732 | ret = dio_send_cur_page(dio); |
733 | page_cache_release(dio->cur_page); |
734 | dio->cur_page = NULL; |
735 | } |
736 | goto out; |
737 | } |
738 | |
739 | /* |
740 | * If there's a deferred page already there then send it. |
741 | */ |
742 | if (dio->cur_page) { |
743 | ret = dio_send_cur_page(dio); |
744 | page_cache_release(dio->cur_page); |
745 | dio->cur_page = NULL; |
746 | if (ret) |
747 | goto out; |
748 | } |
749 | |
750 | page_cache_get(page); /* It is in dio */ |
751 | dio->cur_page = page; |
752 | dio->cur_page_offset = offset; |
753 | dio->cur_page_len = len; |
754 | dio->cur_page_block = blocknr; |
755 | dio->cur_page_fs_offset = dio->block_in_file << dio->blkbits; |
756 | out: |
757 | return ret; |
758 | } |
759 | |
760 | /* |
761 | * Clean any dirty buffers in the blockdev mapping which alias newly-created |
762 | * file blocks. Only called for S_ISREG files - blockdevs do not set |
763 | * buffer_new |
764 | */ |
765 | static void clean_blockdev_aliases(struct dio *dio) |
766 | { |
767 | unsigned i; |
768 | unsigned nblocks; |
769 | |
770 | nblocks = dio->map_bh.b_size >> dio->inode->i_blkbits; |
771 | |
772 | for (i = 0; i < nblocks; i++) { |
773 | unmap_underlying_metadata(dio->map_bh.b_bdev, |
774 | dio->map_bh.b_blocknr + i); |
775 | } |
776 | } |
777 | |
778 | /* |
779 | * If we are not writing the entire block and get_block() allocated |
780 | * the block for us, we need to fill-in the unused portion of the |
781 | * block with zeros. This happens only if user-buffer, fileoffset or |
782 | * io length is not filesystem block-size multiple. |
783 | * |
784 | * `end' is zero if we're doing the start of the IO, 1 at the end of the |
785 | * IO. |
786 | */ |
787 | static void dio_zero_block(struct dio *dio, int end) |
788 | { |
789 | unsigned dio_blocks_per_fs_block; |
790 | unsigned this_chunk_blocks; /* In dio_blocks */ |
791 | unsigned this_chunk_bytes; |
792 | struct page *page; |
793 | |
794 | dio->start_zero_done = 1; |
795 | if (!dio->blkfactor || !buffer_new(&dio->map_bh)) |
796 | return; |
797 | |
798 | dio_blocks_per_fs_block = 1 << dio->blkfactor; |
799 | this_chunk_blocks = dio->block_in_file & (dio_blocks_per_fs_block - 1); |
800 | |
801 | if (!this_chunk_blocks) |
802 | return; |
803 | |
804 | /* |
805 | * We need to zero out part of an fs block. It is either at the |
806 | * beginning or the end of the fs block. |
807 | */ |
808 | if (end) |
809 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; |
810 | |
811 | this_chunk_bytes = this_chunk_blocks << dio->blkbits; |
812 | |
813 | page = ZERO_PAGE(0); |
814 | if (submit_page_section(dio, page, 0, this_chunk_bytes, |
815 | dio->next_block_for_io)) |
816 | return; |
817 | |
818 | dio->next_block_for_io += this_chunk_blocks; |
819 | } |
820 | |
821 | /* |
822 | * Walk the user pages, and the file, mapping blocks to disk and generating |
823 | * a sequence of (page,offset,len,block) mappings. These mappings are injected |
824 | * into submit_page_section(), which takes care of the next stage of submission |
825 | * |
826 | * Direct IO against a blockdev is different from a file. Because we can |
827 | * happily perform page-sized but 512-byte aligned IOs. It is important that |
828 | * blockdev IO be able to have fine alignment and large sizes. |
829 | * |
830 | * So what we do is to permit the ->get_block function to populate bh.b_size |
831 | * with the size of IO which is permitted at this offset and this i_blkbits. |
832 | * |
833 | * For best results, the blockdev should be set up with 512-byte i_blkbits and |
834 | * it should set b_size to PAGE_SIZE or more inside get_block(). This gives |
835 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
836 | */ |
837 | static int do_direct_IO(struct dio *dio) |
838 | { |
839 | const unsigned blkbits = dio->blkbits; |
840 | const unsigned blocks_per_page = PAGE_SIZE >> blkbits; |
841 | struct page *page; |
842 | unsigned block_in_page; |
843 | struct buffer_head *map_bh = &dio->map_bh; |
844 | int ret = 0; |
845 | |
846 | /* The I/O can start at any block offset within the first page */ |
847 | block_in_page = dio->first_block_in_page; |
848 | |
849 | while (dio->block_in_file < dio->final_block_in_request) { |
850 | page = dio_get_page(dio); |
851 | if (IS_ERR(page)) { |
852 | ret = PTR_ERR(page); |
853 | goto out; |
854 | } |
855 | |
856 | while (block_in_page < blocks_per_page) { |
857 | unsigned offset_in_page = block_in_page << blkbits; |
858 | unsigned this_chunk_bytes; /* # of bytes mapped */ |
859 | unsigned this_chunk_blocks; /* # of blocks */ |
860 | unsigned u; |
861 | |
862 | if (dio->blocks_available == 0) { |
863 | /* |
864 | * Need to go and map some more disk |
865 | */ |
866 | unsigned long blkmask; |
867 | unsigned long dio_remainder; |
868 | |
869 | ret = get_more_blocks(dio); |
870 | if (ret) { |
871 | page_cache_release(page); |
872 | goto out; |
873 | } |
874 | if (!buffer_mapped(map_bh)) |
875 | goto do_holes; |
876 | |
877 | dio->blocks_available = |
878 | map_bh->b_size >> dio->blkbits; |
879 | dio->next_block_for_io = |
880 | map_bh->b_blocknr << dio->blkfactor; |
881 | if (buffer_new(map_bh)) |
882 | clean_blockdev_aliases(dio); |
883 | |
884 | if (!dio->blkfactor) |
885 | goto do_holes; |
886 | |
887 | blkmask = (1 << dio->blkfactor) - 1; |
888 | dio_remainder = (dio->block_in_file & blkmask); |
889 | |
890 | /* |
891 | * If we are at the start of IO and that IO |
892 | * starts partway into a fs-block, |
893 | * dio_remainder will be non-zero. If the IO |
894 | * is a read then we can simply advance the IO |
895 | * cursor to the first block which is to be |
896 | * read. But if the IO is a write and the |
897 | * block was newly allocated we cannot do that; |
898 | * the start of the fs block must be zeroed out |
899 | * on-disk |
900 | */ |
901 | if (!buffer_new(map_bh)) |
902 | dio->next_block_for_io += dio_remainder; |
903 | dio->blocks_available -= dio_remainder; |
904 | } |
905 | do_holes: |
906 | /* Handle holes */ |
907 | if (!buffer_mapped(map_bh)) { |
908 | loff_t i_size_aligned; |
909 | |
910 | /* AKPM: eargh, -ENOTBLK is a hack */ |
911 | if (dio->rw & WRITE) { |
912 | page_cache_release(page); |
913 | return -ENOTBLK; |
914 | } |
915 | |
916 | /* |
917 | * Be sure to account for a partial block as the |
918 | * last block in the file |
919 | */ |
920 | i_size_aligned = ALIGN(i_size_read(dio->inode), |
921 | 1 << blkbits); |
922 | if (dio->block_in_file >= |
923 | i_size_aligned >> blkbits) { |
924 | /* We hit eof */ |
925 | page_cache_release(page); |
926 | goto out; |
927 | } |
928 | zero_user(page, block_in_page << blkbits, |
929 | 1 << blkbits); |
930 | dio->block_in_file++; |
931 | block_in_page++; |
932 | goto next_block; |
933 | } |
934 | |
935 | /* |
936 | * If we're performing IO which has an alignment which |
937 | * is finer than the underlying fs, go check to see if |
938 | * we must zero out the start of this block. |
939 | */ |
940 | if (unlikely(dio->blkfactor && !dio->start_zero_done)) |
941 | dio_zero_block(dio, 0); |
942 | |
943 | /* |
944 | * Work out, in this_chunk_blocks, how much disk we |
945 | * can add to this page |
946 | */ |
947 | this_chunk_blocks = dio->blocks_available; |
948 | u = (PAGE_SIZE - offset_in_page) >> blkbits; |
949 | if (this_chunk_blocks > u) |
950 | this_chunk_blocks = u; |
951 | u = dio->final_block_in_request - dio->block_in_file; |
952 | if (this_chunk_blocks > u) |
953 | this_chunk_blocks = u; |
954 | this_chunk_bytes = this_chunk_blocks << blkbits; |
955 | BUG_ON(this_chunk_bytes == 0); |
956 | |
957 | dio->boundary = buffer_boundary(map_bh); |
958 | ret = submit_page_section(dio, page, offset_in_page, |
959 | this_chunk_bytes, dio->next_block_for_io); |
960 | if (ret) { |
961 | page_cache_release(page); |
962 | goto out; |
963 | } |
964 | dio->next_block_for_io += this_chunk_blocks; |
965 | |
966 | dio->block_in_file += this_chunk_blocks; |
967 | block_in_page += this_chunk_blocks; |
968 | dio->blocks_available -= this_chunk_blocks; |
969 | next_block: |
970 | BUG_ON(dio->block_in_file > dio->final_block_in_request); |
971 | if (dio->block_in_file == dio->final_block_in_request) |
972 | break; |
973 | } |
974 | |
975 | /* Drop the ref which was taken in get_user_pages() */ |
976 | page_cache_release(page); |
977 | block_in_page = 0; |
978 | } |
979 | out: |
980 | return ret; |
981 | } |
982 | |
983 | /* |
984 | * Releases both i_mutex and i_alloc_sem |
985 | */ |
986 | static ssize_t |
987 | direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, |
988 | const struct iovec *iov, loff_t offset, unsigned long nr_segs, |
989 | unsigned blkbits, get_block_t get_block, dio_iodone_t end_io, |
990 | dio_submit_t submit_io, struct dio *dio) |
991 | { |
992 | unsigned long user_addr; |
993 | unsigned long flags; |
994 | int seg; |
995 | ssize_t ret = 0; |
996 | ssize_t ret2; |
997 | size_t bytes; |
998 | |
999 | dio->inode = inode; |
1000 | dio->rw = rw; |
1001 | dio->blkbits = blkbits; |
1002 | dio->blkfactor = inode->i_blkbits - blkbits; |
1003 | dio->block_in_file = offset >> blkbits; |
1004 | |
1005 | dio->get_block = get_block; |
1006 | dio->end_io = end_io; |
1007 | dio->submit_io = submit_io; |
1008 | dio->final_block_in_bio = -1; |
1009 | dio->next_block_for_io = -1; |
1010 | |
1011 | dio->iocb = iocb; |
1012 | dio->i_size = i_size_read(inode); |
1013 | |
1014 | spin_lock_init(&dio->bio_lock); |
1015 | dio->refcount = 1; |
1016 | |
1017 | /* |
1018 | * In case of non-aligned buffers, we may need 2 more |
1019 | * pages since we need to zero out first and last block. |
1020 | */ |
1021 | if (unlikely(dio->blkfactor)) |
1022 | dio->pages_in_io = 2; |
1023 | |
1024 | for (seg = 0; seg < nr_segs; seg++) { |
1025 | user_addr = (unsigned long)iov[seg].iov_base; |
1026 | dio->pages_in_io += |
1027 | ((user_addr+iov[seg].iov_len +PAGE_SIZE-1)/PAGE_SIZE |
1028 | - user_addr/PAGE_SIZE); |
1029 | } |
1030 | |
1031 | for (seg = 0; seg < nr_segs; seg++) { |
1032 | user_addr = (unsigned long)iov[seg].iov_base; |
1033 | dio->size += bytes = iov[seg].iov_len; |
1034 | |
1035 | /* Index into the first page of the first block */ |
1036 | dio->first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits; |
1037 | dio->final_block_in_request = dio->block_in_file + |
1038 | (bytes >> blkbits); |
1039 | /* Page fetching state */ |
1040 | dio->head = 0; |
1041 | dio->tail = 0; |
1042 | dio->curr_page = 0; |
1043 | |
1044 | dio->total_pages = 0; |
1045 | if (user_addr & (PAGE_SIZE-1)) { |
1046 | dio->total_pages++; |
1047 | bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1)); |
1048 | } |
1049 | dio->total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE; |
1050 | dio->curr_user_address = user_addr; |
1051 | |
1052 | ret = do_direct_IO(dio); |
1053 | |
1054 | dio->result += iov[seg].iov_len - |
1055 | ((dio->final_block_in_request - dio->block_in_file) << |
1056 | blkbits); |
1057 | |
1058 | if (ret) { |
1059 | dio_cleanup(dio); |
1060 | break; |
1061 | } |
1062 | } /* end iovec loop */ |
1063 | |
1064 | if (ret == -ENOTBLK) { |
1065 | /* |
1066 | * The remaining part of the request will be |
1067 | * be handled by buffered I/O when we return |
1068 | */ |
1069 | ret = 0; |
1070 | } |
1071 | /* |
1072 | * There may be some unwritten disk at the end of a part-written |
1073 | * fs-block-sized block. Go zero that now. |
1074 | */ |
1075 | dio_zero_block(dio, 1); |
1076 | |
1077 | if (dio->cur_page) { |
1078 | ret2 = dio_send_cur_page(dio); |
1079 | if (ret == 0) |
1080 | ret = ret2; |
1081 | page_cache_release(dio->cur_page); |
1082 | dio->cur_page = NULL; |
1083 | } |
1084 | if (dio->bio) |
1085 | dio_bio_submit(dio); |
1086 | |
1087 | /* |
1088 | * It is possible that, we return short IO due to end of file. |
1089 | * In that case, we need to release all the pages we got hold on. |
1090 | */ |
1091 | dio_cleanup(dio); |
1092 | |
1093 | /* |
1094 | * All block lookups have been performed. For READ requests |
1095 | * we can let i_mutex go now that its achieved its purpose |
1096 | * of protecting us from looking up uninitialized blocks. |
1097 | */ |
1098 | if (rw == READ && (dio->flags & DIO_LOCKING)) |
1099 | mutex_unlock(&dio->inode->i_mutex); |
1100 | |
1101 | /* |
1102 | * The only time we want to leave bios in flight is when a successful |
1103 | * partial aio read or full aio write have been setup. In that case |
1104 | * bio completion will call aio_complete. The only time it's safe to |
1105 | * call aio_complete is when we return -EIOCBQUEUED, so we key on that. |
1106 | * This had *better* be the only place that raises -EIOCBQUEUED. |
1107 | */ |
1108 | BUG_ON(ret == -EIOCBQUEUED); |
1109 | if (dio->is_async && ret == 0 && dio->result && |
1110 | ((rw & READ) || (dio->result == dio->size))) |
1111 | ret = -EIOCBQUEUED; |
1112 | |
1113 | if (ret != -EIOCBQUEUED) { |
1114 | /* All IO is now issued, send it on its way */ |
1115 | blk_run_address_space(inode->i_mapping); |
1116 | dio_await_completion(dio); |
1117 | } |
1118 | |
1119 | /* |
1120 | * Sync will always be dropping the final ref and completing the |
1121 | * operation. AIO can if it was a broken operation described above or |
1122 | * in fact if all the bios race to complete before we get here. In |
1123 | * that case dio_complete() translates the EIOCBQUEUED into the proper |
1124 | * return code that the caller will hand to aio_complete(). |
1125 | * |
1126 | * This is managed by the bio_lock instead of being an atomic_t so that |
1127 | * completion paths can drop their ref and use the remaining count to |
1128 | * decide to wake the submission path atomically. |
1129 | */ |
1130 | spin_lock_irqsave(&dio->bio_lock, flags); |
1131 | ret2 = --dio->refcount; |
1132 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
1133 | |
1134 | if (ret2 == 0) { |
1135 | ret = dio_complete(dio, offset, ret, false); |
1136 | kfree(dio); |
1137 | } else |
1138 | BUG_ON(ret != -EIOCBQUEUED); |
1139 | |
1140 | return ret; |
1141 | } |
1142 | |
1143 | /* |
1144 | * This is a library function for use by filesystem drivers. |
1145 | * |
1146 | * The locking rules are governed by the flags parameter: |
1147 | * - if the flags value contains DIO_LOCKING we use a fancy locking |
1148 | * scheme for dumb filesystems. |
1149 | * For writes this function is called under i_mutex and returns with |
1150 | * i_mutex held, for reads, i_mutex is not held on entry, but it is |
1151 | * taken and dropped again before returning. |
1152 | * For reads and writes i_alloc_sem is taken in shared mode and released |
1153 | * on I/O completion (which may happen asynchronously after returning to |
1154 | * the caller). |
1155 | * |
1156 | * - if the flags value does NOT contain DIO_LOCKING we don't use any |
1157 | * internal locking but rather rely on the filesystem to synchronize |
1158 | * direct I/O reads/writes versus each other and truncate. |
1159 | * For reads and writes both i_mutex and i_alloc_sem are not held on |
1160 | * entry and are never taken. |
1161 | */ |
1162 | ssize_t |
1163 | __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, |
1164 | struct block_device *bdev, const struct iovec *iov, loff_t offset, |
1165 | unsigned long nr_segs, get_block_t get_block, dio_iodone_t end_io, |
1166 | dio_submit_t submit_io, int flags) |
1167 | { |
1168 | int seg; |
1169 | size_t size; |
1170 | unsigned long addr; |
1171 | unsigned blkbits = inode->i_blkbits; |
1172 | unsigned bdev_blkbits = 0; |
1173 | unsigned blocksize_mask = (1 << blkbits) - 1; |
1174 | ssize_t retval = -EINVAL; |
1175 | loff_t end = offset; |
1176 | struct dio *dio; |
1177 | |
1178 | if (rw & WRITE) |
1179 | rw = WRITE_ODIRECT_PLUG; |
1180 | |
1181 | if (bdev) |
1182 | bdev_blkbits = blksize_bits(bdev_logical_block_size(bdev)); |
1183 | |
1184 | if (offset & blocksize_mask) { |
1185 | if (bdev) |
1186 | blkbits = bdev_blkbits; |
1187 | blocksize_mask = (1 << blkbits) - 1; |
1188 | if (offset & blocksize_mask) |
1189 | goto out; |
1190 | } |
1191 | |
1192 | /* Check the memory alignment. Blocks cannot straddle pages */ |
1193 | for (seg = 0; seg < nr_segs; seg++) { |
1194 | addr = (unsigned long)iov[seg].iov_base; |
1195 | size = iov[seg].iov_len; |
1196 | end += size; |
1197 | if ((addr & blocksize_mask) || (size & blocksize_mask)) { |
1198 | if (bdev) |
1199 | blkbits = bdev_blkbits; |
1200 | blocksize_mask = (1 << blkbits) - 1; |
1201 | if ((addr & blocksize_mask) || (size & blocksize_mask)) |
1202 | goto out; |
1203 | } |
1204 | } |
1205 | |
1206 | dio = kmalloc(sizeof(*dio), GFP_KERNEL); |
1207 | retval = -ENOMEM; |
1208 | if (!dio) |
1209 | goto out; |
1210 | /* |
1211 | * Believe it or not, zeroing out the page array caused a .5% |
1212 | * performance regression in a database benchmark. So, we take |
1213 | * care to only zero out what's needed. |
1214 | */ |
1215 | memset(dio, 0, offsetof(struct dio, pages)); |
1216 | |
1217 | dio->flags = flags; |
1218 | if (dio->flags & DIO_LOCKING) { |
1219 | /* watch out for a 0 len io from a tricksy fs */ |
1220 | if (rw == READ && end > offset) { |
1221 | struct address_space *mapping = |
1222 | iocb->ki_filp->f_mapping; |
1223 | |
1224 | /* will be released by direct_io_worker */ |
1225 | mutex_lock(&inode->i_mutex); |
1226 | |
1227 | retval = filemap_write_and_wait_range(mapping, offset, |
1228 | end - 1); |
1229 | if (retval) { |
1230 | mutex_unlock(&inode->i_mutex); |
1231 | kfree(dio); |
1232 | goto out; |
1233 | } |
1234 | } |
1235 | |
1236 | /* |
1237 | * Will be released at I/O completion, possibly in a |
1238 | * different thread. |
1239 | */ |
1240 | down_read_non_owner(&inode->i_alloc_sem); |
1241 | } |
1242 | |
1243 | /* |
1244 | * For file extending writes updating i_size before data |
1245 | * writeouts complete can expose uninitialized blocks. So |
1246 | * even for AIO, we need to wait for i/o to complete before |
1247 | * returning in this case. |
1248 | */ |
1249 | dio->is_async = !is_sync_kiocb(iocb) && !((rw & WRITE) && |
1250 | (end > i_size_read(inode))); |
1251 | |
1252 | retval = direct_io_worker(rw, iocb, inode, iov, offset, |
1253 | nr_segs, blkbits, get_block, end_io, |
1254 | submit_io, dio); |
1255 | |
1256 | out: |
1257 | return retval; |
1258 | } |
1259 | EXPORT_SYMBOL(__blockdev_direct_IO); |
1260 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
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jz-3.6-rc2-pwm
jz-3.9
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jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9