Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/fs/direct-io.c
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
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Wed Mar 4 11:03:09 2009 UTC (15 years, 6 months ago) by niro
File MIME type: text/plain
File size: 35328 byte(s)
Tag kernel26-2.6.12-alx-r9
1 | /* |
2 | * fs/direct-io.c |
3 | * |
4 | * Copyright (C) 2002, Linus Torvalds. |
5 | * |
6 | * O_DIRECT |
7 | * |
8 | * 04Jul2002 akpm@zip.com.au |
9 | * Initial version |
10 | * 11Sep2002 janetinc@us.ibm.com |
11 | * added readv/writev support. |
12 | * 29Oct2002 akpm@zip.com.au |
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/bio.h> |
31 | #include <linux/wait.h> |
32 | #include <linux/err.h> |
33 | #include <linux/blkdev.h> |
34 | #include <linux/buffer_head.h> |
35 | #include <linux/rwsem.h> |
36 | #include <linux/uio.h> |
37 | #include <asm/atomic.h> |
38 | |
39 | /* |
40 | * How many user pages to map in one call to get_user_pages(). This determines |
41 | * the size of a structure on the stack. |
42 | */ |
43 | #define DIO_PAGES 64 |
44 | |
45 | /* |
46 | * This code generally works in units of "dio_blocks". A dio_block is |
47 | * somewhere between the hard sector size and the filesystem block size. it |
48 | * is determined on a per-invocation basis. When talking to the filesystem |
49 | * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity |
50 | * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted |
51 | * to bio_block quantities by shifting left by blkfactor. |
52 | * |
53 | * If blkfactor is zero then the user's request was aligned to the filesystem's |
54 | * blocksize. |
55 | * |
56 | * lock_type is DIO_LOCKING for regular files on direct-IO-naive filesystems. |
57 | * This determines whether we need to do the fancy locking which prevents |
58 | * direct-IO from being able to read uninitialised disk blocks. If its zero |
59 | * (blockdev) this locking is not done, and if it is DIO_OWN_LOCKING i_sem is |
60 | * not held for the entire direct write (taken briefly, initially, during a |
61 | * direct read though, but its never held for the duration of a direct-IO). |
62 | */ |
63 | |
64 | struct dio { |
65 | /* BIO submission state */ |
66 | struct bio *bio; /* bio under assembly */ |
67 | struct inode *inode; |
68 | int rw; |
69 | loff_t i_size; /* i_size when submitted */ |
70 | int lock_type; /* doesn't change */ |
71 | unsigned blkbits; /* doesn't change */ |
72 | unsigned blkfactor; /* When we're using an alignment which |
73 | is finer than the filesystem's soft |
74 | blocksize, this specifies how much |
75 | finer. blkfactor=2 means 1/4-block |
76 | alignment. Does not change */ |
77 | unsigned start_zero_done; /* flag: sub-blocksize zeroing has |
78 | been performed at the start of a |
79 | write */ |
80 | int pages_in_io; /* approximate total IO pages */ |
81 | size_t size; /* total request size (doesn't change)*/ |
82 | sector_t block_in_file; /* Current offset into the underlying |
83 | file in dio_block units. */ |
84 | unsigned blocks_available; /* At block_in_file. changes */ |
85 | sector_t final_block_in_request;/* doesn't change */ |
86 | unsigned first_block_in_page; /* doesn't change, Used only once */ |
87 | int boundary; /* prev block is at a boundary */ |
88 | int reap_counter; /* rate limit reaping */ |
89 | get_blocks_t *get_blocks; /* block mapping function */ |
90 | dio_iodone_t *end_io; /* IO completion function */ |
91 | sector_t final_block_in_bio; /* current final block in bio + 1 */ |
92 | sector_t next_block_for_io; /* next block to be put under IO, |
93 | in dio_blocks units */ |
94 | struct buffer_head map_bh; /* last get_blocks() result */ |
95 | |
96 | /* |
97 | * Deferred addition of a page to the dio. These variables are |
98 | * private to dio_send_cur_page(), submit_page_section() and |
99 | * dio_bio_add_page(). |
100 | */ |
101 | struct page *cur_page; /* The page */ |
102 | unsigned cur_page_offset; /* Offset into it, in bytes */ |
103 | unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ |
104 | sector_t cur_page_block; /* Where it starts */ |
105 | |
106 | /* |
107 | * Page fetching state. These variables belong to dio_refill_pages(). |
108 | */ |
109 | int curr_page; /* changes */ |
110 | int total_pages; /* doesn't change */ |
111 | unsigned long curr_user_address;/* changes */ |
112 | |
113 | /* |
114 | * Page queue. These variables belong to dio_refill_pages() and |
115 | * dio_get_page(). |
116 | */ |
117 | struct page *pages[DIO_PAGES]; /* page buffer */ |
118 | unsigned head; /* next page to process */ |
119 | unsigned tail; /* last valid page + 1 */ |
120 | int page_errors; /* errno from get_user_pages() */ |
121 | |
122 | /* BIO completion state */ |
123 | spinlock_t bio_lock; /* protects BIO fields below */ |
124 | int bio_count; /* nr bios to be completed */ |
125 | int bios_in_flight; /* nr bios in flight */ |
126 | struct bio *bio_list; /* singly linked via bi_private */ |
127 | struct task_struct *waiter; /* waiting task (NULL if none) */ |
128 | |
129 | /* AIO related stuff */ |
130 | struct kiocb *iocb; /* kiocb */ |
131 | int is_async; /* is IO async ? */ |
132 | ssize_t result; /* IO result */ |
133 | }; |
134 | |
135 | /* |
136 | * How many pages are in the queue? |
137 | */ |
138 | static inline unsigned dio_pages_present(struct dio *dio) |
139 | { |
140 | return dio->tail - dio->head; |
141 | } |
142 | |
143 | /* |
144 | * Go grab and pin some userspace pages. Typically we'll get 64 at a time. |
145 | */ |
146 | static int dio_refill_pages(struct dio *dio) |
147 | { |
148 | int ret; |
149 | int nr_pages; |
150 | |
151 | nr_pages = min(dio->total_pages - dio->curr_page, DIO_PAGES); |
152 | down_read(¤t->mm->mmap_sem); |
153 | ret = get_user_pages( |
154 | current, /* Task for fault acounting */ |
155 | current->mm, /* whose pages? */ |
156 | dio->curr_user_address, /* Where from? */ |
157 | nr_pages, /* How many pages? */ |
158 | dio->rw == READ, /* Write to memory? */ |
159 | 0, /* force (?) */ |
160 | &dio->pages[0], |
161 | NULL); /* vmas */ |
162 | up_read(¤t->mm->mmap_sem); |
163 | |
164 | if (ret < 0 && dio->blocks_available && (dio->rw == WRITE)) { |
165 | /* |
166 | * A memory fault, but the filesystem has some outstanding |
167 | * mapped blocks. We need to use those blocks up to avoid |
168 | * leaking stale data in the file. |
169 | */ |
170 | if (dio->page_errors == 0) |
171 | dio->page_errors = ret; |
172 | dio->pages[0] = ZERO_PAGE(dio->curr_user_address); |
173 | dio->head = 0; |
174 | dio->tail = 1; |
175 | ret = 0; |
176 | goto out; |
177 | } |
178 | |
179 | if (ret >= 0) { |
180 | dio->curr_user_address += ret * PAGE_SIZE; |
181 | dio->curr_page += ret; |
182 | dio->head = 0; |
183 | dio->tail = ret; |
184 | ret = 0; |
185 | } |
186 | out: |
187 | return ret; |
188 | } |
189 | |
190 | /* |
191 | * Get another userspace page. Returns an ERR_PTR on error. Pages are |
192 | * buffered inside the dio so that we can call get_user_pages() against a |
193 | * decent number of pages, less frequently. To provide nicer use of the |
194 | * L1 cache. |
195 | */ |
196 | static struct page *dio_get_page(struct dio *dio) |
197 | { |
198 | if (dio_pages_present(dio) == 0) { |
199 | int ret; |
200 | |
201 | ret = dio_refill_pages(dio); |
202 | if (ret) |
203 | return ERR_PTR(ret); |
204 | BUG_ON(dio_pages_present(dio) == 0); |
205 | } |
206 | return dio->pages[dio->head++]; |
207 | } |
208 | |
209 | /* |
210 | * Called when all DIO BIO I/O has been completed - let the filesystem |
211 | * know, if it registered an interest earlier via get_blocks. Pass the |
212 | * private field of the map buffer_head so that filesystems can use it |
213 | * to hold additional state between get_blocks calls and dio_complete. |
214 | */ |
215 | static void dio_complete(struct dio *dio, loff_t offset, ssize_t bytes) |
216 | { |
217 | if (dio->end_io && dio->result) |
218 | dio->end_io(dio->inode, offset, bytes, dio->map_bh.b_private); |
219 | if (dio->lock_type == DIO_LOCKING) |
220 | up_read(&dio->inode->i_alloc_sem); |
221 | } |
222 | |
223 | /* |
224 | * Called when a BIO has been processed. If the count goes to zero then IO is |
225 | * complete and we can signal this to the AIO layer. |
226 | */ |
227 | static void finished_one_bio(struct dio *dio) |
228 | { |
229 | unsigned long flags; |
230 | |
231 | spin_lock_irqsave(&dio->bio_lock, flags); |
232 | if (dio->bio_count == 1) { |
233 | if (dio->is_async) { |
234 | ssize_t transferred; |
235 | loff_t offset; |
236 | |
237 | /* |
238 | * Last reference to the dio is going away. |
239 | * Drop spinlock and complete the DIO. |
240 | */ |
241 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
242 | |
243 | /* Check for short read case */ |
244 | transferred = dio->result; |
245 | offset = dio->iocb->ki_pos; |
246 | |
247 | if ((dio->rw == READ) && |
248 | ((offset + transferred) > dio->i_size)) |
249 | transferred = dio->i_size - offset; |
250 | |
251 | dio_complete(dio, offset, transferred); |
252 | |
253 | /* Complete AIO later if falling back to buffered i/o */ |
254 | if (dio->result == dio->size || |
255 | ((dio->rw == READ) && dio->result)) { |
256 | aio_complete(dio->iocb, transferred, 0); |
257 | kfree(dio); |
258 | return; |
259 | } else { |
260 | /* |
261 | * Falling back to buffered |
262 | */ |
263 | spin_lock_irqsave(&dio->bio_lock, flags); |
264 | dio->bio_count--; |
265 | if (dio->waiter) |
266 | wake_up_process(dio->waiter); |
267 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
268 | return; |
269 | } |
270 | } |
271 | } |
272 | dio->bio_count--; |
273 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
274 | } |
275 | |
276 | static int dio_bio_complete(struct dio *dio, struct bio *bio); |
277 | /* |
278 | * Asynchronous IO callback. |
279 | */ |
280 | static int dio_bio_end_aio(struct bio *bio, unsigned int bytes_done, int error) |
281 | { |
282 | struct dio *dio = bio->bi_private; |
283 | |
284 | if (bio->bi_size) |
285 | return 1; |
286 | |
287 | /* cleanup the bio */ |
288 | dio_bio_complete(dio, bio); |
289 | return 0; |
290 | } |
291 | |
292 | /* |
293 | * The BIO completion handler simply queues the BIO up for the process-context |
294 | * handler. |
295 | * |
296 | * During I/O bi_private points at the dio. After I/O, bi_private is used to |
297 | * implement a singly-linked list of completed BIOs, at dio->bio_list. |
298 | */ |
299 | static int dio_bio_end_io(struct bio *bio, unsigned int bytes_done, int error) |
300 | { |
301 | struct dio *dio = bio->bi_private; |
302 | unsigned long flags; |
303 | |
304 | if (bio->bi_size) |
305 | return 1; |
306 | |
307 | spin_lock_irqsave(&dio->bio_lock, flags); |
308 | bio->bi_private = dio->bio_list; |
309 | dio->bio_list = bio; |
310 | dio->bios_in_flight--; |
311 | if (dio->waiter && dio->bios_in_flight == 0) |
312 | wake_up_process(dio->waiter); |
313 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
314 | return 0; |
315 | } |
316 | |
317 | static int |
318 | dio_bio_alloc(struct dio *dio, struct block_device *bdev, |
319 | sector_t first_sector, int nr_vecs) |
320 | { |
321 | struct bio *bio; |
322 | |
323 | bio = bio_alloc(GFP_KERNEL, nr_vecs); |
324 | if (bio == NULL) |
325 | return -ENOMEM; |
326 | |
327 | bio->bi_bdev = bdev; |
328 | bio->bi_sector = first_sector; |
329 | if (dio->is_async) |
330 | bio->bi_end_io = dio_bio_end_aio; |
331 | else |
332 | bio->bi_end_io = dio_bio_end_io; |
333 | |
334 | dio->bio = bio; |
335 | return 0; |
336 | } |
337 | |
338 | /* |
339 | * In the AIO read case we speculatively dirty the pages before starting IO. |
340 | * During IO completion, any of these pages which happen to have been written |
341 | * back will be redirtied by bio_check_pages_dirty(). |
342 | */ |
343 | static void dio_bio_submit(struct dio *dio) |
344 | { |
345 | struct bio *bio = dio->bio; |
346 | unsigned long flags; |
347 | |
348 | bio->bi_private = dio; |
349 | spin_lock_irqsave(&dio->bio_lock, flags); |
350 | dio->bio_count++; |
351 | dio->bios_in_flight++; |
352 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
353 | if (dio->is_async && dio->rw == READ) |
354 | bio_set_pages_dirty(bio); |
355 | submit_bio(dio->rw, bio); |
356 | |
357 | dio->bio = NULL; |
358 | dio->boundary = 0; |
359 | } |
360 | |
361 | /* |
362 | * Release any resources in case of a failure |
363 | */ |
364 | static void dio_cleanup(struct dio *dio) |
365 | { |
366 | while (dio_pages_present(dio)) |
367 | page_cache_release(dio_get_page(dio)); |
368 | } |
369 | |
370 | /* |
371 | * Wait for the next BIO to complete. Remove it and return it. |
372 | */ |
373 | static struct bio *dio_await_one(struct dio *dio) |
374 | { |
375 | unsigned long flags; |
376 | struct bio *bio; |
377 | |
378 | spin_lock_irqsave(&dio->bio_lock, flags); |
379 | while (dio->bio_list == NULL) { |
380 | set_current_state(TASK_UNINTERRUPTIBLE); |
381 | if (dio->bio_list == NULL) { |
382 | dio->waiter = current; |
383 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
384 | blk_run_address_space(dio->inode->i_mapping); |
385 | io_schedule(); |
386 | spin_lock_irqsave(&dio->bio_lock, flags); |
387 | dio->waiter = NULL; |
388 | } |
389 | set_current_state(TASK_RUNNING); |
390 | } |
391 | bio = dio->bio_list; |
392 | dio->bio_list = bio->bi_private; |
393 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
394 | return bio; |
395 | } |
396 | |
397 | /* |
398 | * Process one completed BIO. No locks are held. |
399 | */ |
400 | static int dio_bio_complete(struct dio *dio, struct bio *bio) |
401 | { |
402 | const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags); |
403 | struct bio_vec *bvec = bio->bi_io_vec; |
404 | int page_no; |
405 | |
406 | if (!uptodate) |
407 | dio->result = -EIO; |
408 | |
409 | if (dio->is_async && dio->rw == READ) { |
410 | bio_check_pages_dirty(bio); /* transfers ownership */ |
411 | } else { |
412 | for (page_no = 0; page_no < bio->bi_vcnt; page_no++) { |
413 | struct page *page = bvec[page_no].bv_page; |
414 | |
415 | if (dio->rw == READ && !PageCompound(page)) |
416 | set_page_dirty_lock(page); |
417 | page_cache_release(page); |
418 | } |
419 | bio_put(bio); |
420 | } |
421 | finished_one_bio(dio); |
422 | return uptodate ? 0 : -EIO; |
423 | } |
424 | |
425 | /* |
426 | * Wait on and process all in-flight BIOs. |
427 | */ |
428 | static int dio_await_completion(struct dio *dio) |
429 | { |
430 | int ret = 0; |
431 | |
432 | if (dio->bio) |
433 | dio_bio_submit(dio); |
434 | |
435 | /* |
436 | * The bio_lock is not held for the read of bio_count. |
437 | * This is ok since it is the dio_bio_complete() that changes |
438 | * bio_count. |
439 | */ |
440 | while (dio->bio_count) { |
441 | struct bio *bio = dio_await_one(dio); |
442 | int ret2; |
443 | |
444 | ret2 = dio_bio_complete(dio, bio); |
445 | if (ret == 0) |
446 | ret = ret2; |
447 | } |
448 | return ret; |
449 | } |
450 | |
451 | /* |
452 | * A really large O_DIRECT read or write can generate a lot of BIOs. So |
453 | * to keep the memory consumption sane we periodically reap any completed BIOs |
454 | * during the BIO generation phase. |
455 | * |
456 | * This also helps to limit the peak amount of pinned userspace memory. |
457 | */ |
458 | static int dio_bio_reap(struct dio *dio) |
459 | { |
460 | int ret = 0; |
461 | |
462 | if (dio->reap_counter++ >= 64) { |
463 | while (dio->bio_list) { |
464 | unsigned long flags; |
465 | struct bio *bio; |
466 | int ret2; |
467 | |
468 | spin_lock_irqsave(&dio->bio_lock, flags); |
469 | bio = dio->bio_list; |
470 | dio->bio_list = bio->bi_private; |
471 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
472 | ret2 = dio_bio_complete(dio, bio); |
473 | if (ret == 0) |
474 | ret = ret2; |
475 | } |
476 | dio->reap_counter = 0; |
477 | } |
478 | return ret; |
479 | } |
480 | |
481 | /* |
482 | * Call into the fs to map some more disk blocks. We record the current number |
483 | * of available blocks at dio->blocks_available. These are in units of the |
484 | * fs blocksize, (1 << inode->i_blkbits). |
485 | * |
486 | * The fs is allowed to map lots of blocks at once. If it wants to do that, |
487 | * it uses the passed inode-relative block number as the file offset, as usual. |
488 | * |
489 | * get_blocks() is passed the number of i_blkbits-sized blocks which direct_io |
490 | * has remaining to do. The fs should not map more than this number of blocks. |
491 | * |
492 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to |
493 | * indicate how much contiguous disk space has been made available at |
494 | * bh->b_blocknr. |
495 | * |
496 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). |
497 | * This isn't very efficient... |
498 | * |
499 | * In the case of filesystem holes: the fs may return an arbitrarily-large |
500 | * hole by returning an appropriate value in b_size and by clearing |
501 | * buffer_mapped(). However the direct-io code will only process holes one |
502 | * block at a time - it will repeatedly call get_blocks() as it walks the hole. |
503 | */ |
504 | static int get_more_blocks(struct dio *dio) |
505 | { |
506 | int ret; |
507 | struct buffer_head *map_bh = &dio->map_bh; |
508 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ |
509 | unsigned long fs_count; /* Number of filesystem-sized blocks */ |
510 | unsigned long dio_count;/* Number of dio_block-sized blocks */ |
511 | unsigned long blkmask; |
512 | int create; |
513 | |
514 | /* |
515 | * If there was a memory error and we've overwritten all the |
516 | * mapped blocks then we can now return that memory error |
517 | */ |
518 | ret = dio->page_errors; |
519 | if (ret == 0) { |
520 | map_bh->b_state = 0; |
521 | map_bh->b_size = 0; |
522 | BUG_ON(dio->block_in_file >= dio->final_block_in_request); |
523 | fs_startblk = dio->block_in_file >> dio->blkfactor; |
524 | dio_count = dio->final_block_in_request - dio->block_in_file; |
525 | fs_count = dio_count >> dio->blkfactor; |
526 | blkmask = (1 << dio->blkfactor) - 1; |
527 | if (dio_count & blkmask) |
528 | fs_count++; |
529 | |
530 | create = dio->rw == WRITE; |
531 | if (dio->lock_type == DIO_LOCKING) { |
532 | if (dio->block_in_file < (i_size_read(dio->inode) >> |
533 | dio->blkbits)) |
534 | create = 0; |
535 | } else if (dio->lock_type == DIO_NO_LOCKING) { |
536 | create = 0; |
537 | } |
538 | /* |
539 | * For writes inside i_size we forbid block creations: only |
540 | * overwrites are permitted. We fall back to buffered writes |
541 | * at a higher level for inside-i_size block-instantiating |
542 | * writes. |
543 | */ |
544 | ret = (*dio->get_blocks)(dio->inode, fs_startblk, fs_count, |
545 | map_bh, create); |
546 | } |
547 | return ret; |
548 | } |
549 | |
550 | /* |
551 | * There is no bio. Make one now. |
552 | */ |
553 | static int dio_new_bio(struct dio *dio, sector_t start_sector) |
554 | { |
555 | sector_t sector; |
556 | int ret, nr_pages; |
557 | |
558 | ret = dio_bio_reap(dio); |
559 | if (ret) |
560 | goto out; |
561 | sector = start_sector << (dio->blkbits - 9); |
562 | nr_pages = min(dio->pages_in_io, bio_get_nr_vecs(dio->map_bh.b_bdev)); |
563 | BUG_ON(nr_pages <= 0); |
564 | ret = dio_bio_alloc(dio, dio->map_bh.b_bdev, sector, nr_pages); |
565 | dio->boundary = 0; |
566 | out: |
567 | return ret; |
568 | } |
569 | |
570 | /* |
571 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If |
572 | * that was successful then update final_block_in_bio and take a ref against |
573 | * the just-added page. |
574 | * |
575 | * Return zero on success. Non-zero means the caller needs to start a new BIO. |
576 | */ |
577 | static int dio_bio_add_page(struct dio *dio) |
578 | { |
579 | int ret; |
580 | |
581 | ret = bio_add_page(dio->bio, dio->cur_page, |
582 | dio->cur_page_len, dio->cur_page_offset); |
583 | if (ret == dio->cur_page_len) { |
584 | /* |
585 | * Decrement count only, if we are done with this page |
586 | */ |
587 | if ((dio->cur_page_len + dio->cur_page_offset) == PAGE_SIZE) |
588 | dio->pages_in_io--; |
589 | page_cache_get(dio->cur_page); |
590 | dio->final_block_in_bio = dio->cur_page_block + |
591 | (dio->cur_page_len >> dio->blkbits); |
592 | ret = 0; |
593 | } else { |
594 | ret = 1; |
595 | } |
596 | return ret; |
597 | } |
598 | |
599 | /* |
600 | * Put cur_page under IO. The section of cur_page which is described by |
601 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page |
602 | * starts on-disk at cur_page_block. |
603 | * |
604 | * We take a ref against the page here (on behalf of its presence in the bio). |
605 | * |
606 | * The caller of this function is responsible for removing cur_page from the |
607 | * dio, and for dropping the refcount which came from that presence. |
608 | */ |
609 | static int dio_send_cur_page(struct dio *dio) |
610 | { |
611 | int ret = 0; |
612 | |
613 | if (dio->bio) { |
614 | /* |
615 | * See whether this new request is contiguous with the old |
616 | */ |
617 | if (dio->final_block_in_bio != dio->cur_page_block) |
618 | dio_bio_submit(dio); |
619 | /* |
620 | * Submit now if the underlying fs is about to perform a |
621 | * metadata read |
622 | */ |
623 | if (dio->boundary) |
624 | dio_bio_submit(dio); |
625 | } |
626 | |
627 | if (dio->bio == NULL) { |
628 | ret = dio_new_bio(dio, dio->cur_page_block); |
629 | if (ret) |
630 | goto out; |
631 | } |
632 | |
633 | if (dio_bio_add_page(dio) != 0) { |
634 | dio_bio_submit(dio); |
635 | ret = dio_new_bio(dio, dio->cur_page_block); |
636 | if (ret == 0) { |
637 | ret = dio_bio_add_page(dio); |
638 | BUG_ON(ret != 0); |
639 | } |
640 | } |
641 | out: |
642 | return ret; |
643 | } |
644 | |
645 | /* |
646 | * An autonomous function to put a chunk of a page under deferred IO. |
647 | * |
648 | * The caller doesn't actually know (or care) whether this piece of page is in |
649 | * a BIO, or is under IO or whatever. We just take care of all possible |
650 | * situations here. The separation between the logic of do_direct_IO() and |
651 | * that of submit_page_section() is important for clarity. Please don't break. |
652 | * |
653 | * The chunk of page starts on-disk at blocknr. |
654 | * |
655 | * We perform deferred IO, by recording the last-submitted page inside our |
656 | * private part of the dio structure. If possible, we just expand the IO |
657 | * across that page here. |
658 | * |
659 | * If that doesn't work out then we put the old page into the bio and add this |
660 | * page to the dio instead. |
661 | */ |
662 | static int |
663 | submit_page_section(struct dio *dio, struct page *page, |
664 | unsigned offset, unsigned len, sector_t blocknr) |
665 | { |
666 | int ret = 0; |
667 | |
668 | /* |
669 | * Can we just grow the current page's presence in the dio? |
670 | */ |
671 | if ( (dio->cur_page == page) && |
672 | (dio->cur_page_offset + dio->cur_page_len == offset) && |
673 | (dio->cur_page_block + |
674 | (dio->cur_page_len >> dio->blkbits) == blocknr)) { |
675 | dio->cur_page_len += len; |
676 | |
677 | /* |
678 | * If dio->boundary then we want to schedule the IO now to |
679 | * avoid metadata seeks. |
680 | */ |
681 | if (dio->boundary) { |
682 | ret = dio_send_cur_page(dio); |
683 | page_cache_release(dio->cur_page); |
684 | dio->cur_page = NULL; |
685 | } |
686 | goto out; |
687 | } |
688 | |
689 | /* |
690 | * If there's a deferred page already there then send it. |
691 | */ |
692 | if (dio->cur_page) { |
693 | ret = dio_send_cur_page(dio); |
694 | page_cache_release(dio->cur_page); |
695 | dio->cur_page = NULL; |
696 | if (ret) |
697 | goto out; |
698 | } |
699 | |
700 | page_cache_get(page); /* It is in dio */ |
701 | dio->cur_page = page; |
702 | dio->cur_page_offset = offset; |
703 | dio->cur_page_len = len; |
704 | dio->cur_page_block = blocknr; |
705 | out: |
706 | return ret; |
707 | } |
708 | |
709 | /* |
710 | * Clean any dirty buffers in the blockdev mapping which alias newly-created |
711 | * file blocks. Only called for S_ISREG files - blockdevs do not set |
712 | * buffer_new |
713 | */ |
714 | static void clean_blockdev_aliases(struct dio *dio) |
715 | { |
716 | unsigned i; |
717 | unsigned nblocks; |
718 | |
719 | nblocks = dio->map_bh.b_size >> dio->inode->i_blkbits; |
720 | |
721 | for (i = 0; i < nblocks; i++) { |
722 | unmap_underlying_metadata(dio->map_bh.b_bdev, |
723 | dio->map_bh.b_blocknr + i); |
724 | } |
725 | } |
726 | |
727 | /* |
728 | * If we are not writing the entire block and get_block() allocated |
729 | * the block for us, we need to fill-in the unused portion of the |
730 | * block with zeros. This happens only if user-buffer, fileoffset or |
731 | * io length is not filesystem block-size multiple. |
732 | * |
733 | * `end' is zero if we're doing the start of the IO, 1 at the end of the |
734 | * IO. |
735 | */ |
736 | static void dio_zero_block(struct dio *dio, int end) |
737 | { |
738 | unsigned dio_blocks_per_fs_block; |
739 | unsigned this_chunk_blocks; /* In dio_blocks */ |
740 | unsigned this_chunk_bytes; |
741 | struct page *page; |
742 | |
743 | dio->start_zero_done = 1; |
744 | if (!dio->blkfactor || !buffer_new(&dio->map_bh)) |
745 | return; |
746 | |
747 | dio_blocks_per_fs_block = 1 << dio->blkfactor; |
748 | this_chunk_blocks = dio->block_in_file & (dio_blocks_per_fs_block - 1); |
749 | |
750 | if (!this_chunk_blocks) |
751 | return; |
752 | |
753 | /* |
754 | * We need to zero out part of an fs block. It is either at the |
755 | * beginning or the end of the fs block. |
756 | */ |
757 | if (end) |
758 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; |
759 | |
760 | this_chunk_bytes = this_chunk_blocks << dio->blkbits; |
761 | |
762 | page = ZERO_PAGE(dio->curr_user_address); |
763 | if (submit_page_section(dio, page, 0, this_chunk_bytes, |
764 | dio->next_block_for_io)) |
765 | return; |
766 | |
767 | dio->next_block_for_io += this_chunk_blocks; |
768 | } |
769 | |
770 | /* |
771 | * Walk the user pages, and the file, mapping blocks to disk and generating |
772 | * a sequence of (page,offset,len,block) mappings. These mappings are injected |
773 | * into submit_page_section(), which takes care of the next stage of submission |
774 | * |
775 | * Direct IO against a blockdev is different from a file. Because we can |
776 | * happily perform page-sized but 512-byte aligned IOs. It is important that |
777 | * blockdev IO be able to have fine alignment and large sizes. |
778 | * |
779 | * So what we do is to permit the ->get_blocks function to populate bh.b_size |
780 | * with the size of IO which is permitted at this offset and this i_blkbits. |
781 | * |
782 | * For best results, the blockdev should be set up with 512-byte i_blkbits and |
783 | * it should set b_size to PAGE_SIZE or more inside get_blocks(). This gives |
784 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
785 | */ |
786 | static int do_direct_IO(struct dio *dio) |
787 | { |
788 | const unsigned blkbits = dio->blkbits; |
789 | const unsigned blocks_per_page = PAGE_SIZE >> blkbits; |
790 | struct page *page; |
791 | unsigned block_in_page; |
792 | struct buffer_head *map_bh = &dio->map_bh; |
793 | int ret = 0; |
794 | |
795 | /* The I/O can start at any block offset within the first page */ |
796 | block_in_page = dio->first_block_in_page; |
797 | |
798 | while (dio->block_in_file < dio->final_block_in_request) { |
799 | page = dio_get_page(dio); |
800 | if (IS_ERR(page)) { |
801 | ret = PTR_ERR(page); |
802 | goto out; |
803 | } |
804 | |
805 | while (block_in_page < blocks_per_page) { |
806 | unsigned offset_in_page = block_in_page << blkbits; |
807 | unsigned this_chunk_bytes; /* # of bytes mapped */ |
808 | unsigned this_chunk_blocks; /* # of blocks */ |
809 | unsigned u; |
810 | |
811 | if (dio->blocks_available == 0) { |
812 | /* |
813 | * Need to go and map some more disk |
814 | */ |
815 | unsigned long blkmask; |
816 | unsigned long dio_remainder; |
817 | |
818 | ret = get_more_blocks(dio); |
819 | if (ret) { |
820 | page_cache_release(page); |
821 | goto out; |
822 | } |
823 | if (!buffer_mapped(map_bh)) |
824 | goto do_holes; |
825 | |
826 | dio->blocks_available = |
827 | map_bh->b_size >> dio->blkbits; |
828 | dio->next_block_for_io = |
829 | map_bh->b_blocknr << dio->blkfactor; |
830 | if (buffer_new(map_bh)) |
831 | clean_blockdev_aliases(dio); |
832 | |
833 | if (!dio->blkfactor) |
834 | goto do_holes; |
835 | |
836 | blkmask = (1 << dio->blkfactor) - 1; |
837 | dio_remainder = (dio->block_in_file & blkmask); |
838 | |
839 | /* |
840 | * If we are at the start of IO and that IO |
841 | * starts partway into a fs-block, |
842 | * dio_remainder will be non-zero. If the IO |
843 | * is a read then we can simply advance the IO |
844 | * cursor to the first block which is to be |
845 | * read. But if the IO is a write and the |
846 | * block was newly allocated we cannot do that; |
847 | * the start of the fs block must be zeroed out |
848 | * on-disk |
849 | */ |
850 | if (!buffer_new(map_bh)) |
851 | dio->next_block_for_io += dio_remainder; |
852 | dio->blocks_available -= dio_remainder; |
853 | } |
854 | do_holes: |
855 | /* Handle holes */ |
856 | if (!buffer_mapped(map_bh)) { |
857 | char *kaddr; |
858 | |
859 | /* AKPM: eargh, -ENOTBLK is a hack */ |
860 | if (dio->rw == WRITE) { |
861 | page_cache_release(page); |
862 | return -ENOTBLK; |
863 | } |
864 | |
865 | if (dio->block_in_file >= |
866 | i_size_read(dio->inode)>>blkbits) { |
867 | /* We hit eof */ |
868 | page_cache_release(page); |
869 | goto out; |
870 | } |
871 | kaddr = kmap_atomic(page, KM_USER0); |
872 | memset(kaddr + (block_in_page << blkbits), |
873 | 0, 1 << blkbits); |
874 | flush_dcache_page(page); |
875 | kunmap_atomic(kaddr, KM_USER0); |
876 | dio->block_in_file++; |
877 | block_in_page++; |
878 | goto next_block; |
879 | } |
880 | |
881 | /* |
882 | * If we're performing IO which has an alignment which |
883 | * is finer than the underlying fs, go check to see if |
884 | * we must zero out the start of this block. |
885 | */ |
886 | if (unlikely(dio->blkfactor && !dio->start_zero_done)) |
887 | dio_zero_block(dio, 0); |
888 | |
889 | /* |
890 | * Work out, in this_chunk_blocks, how much disk we |
891 | * can add to this page |
892 | */ |
893 | this_chunk_blocks = dio->blocks_available; |
894 | u = (PAGE_SIZE - offset_in_page) >> blkbits; |
895 | if (this_chunk_blocks > u) |
896 | this_chunk_blocks = u; |
897 | u = dio->final_block_in_request - dio->block_in_file; |
898 | if (this_chunk_blocks > u) |
899 | this_chunk_blocks = u; |
900 | this_chunk_bytes = this_chunk_blocks << blkbits; |
901 | BUG_ON(this_chunk_bytes == 0); |
902 | |
903 | dio->boundary = buffer_boundary(map_bh); |
904 | ret = submit_page_section(dio, page, offset_in_page, |
905 | this_chunk_bytes, dio->next_block_for_io); |
906 | if (ret) { |
907 | page_cache_release(page); |
908 | goto out; |
909 | } |
910 | dio->next_block_for_io += this_chunk_blocks; |
911 | |
912 | dio->block_in_file += this_chunk_blocks; |
913 | block_in_page += this_chunk_blocks; |
914 | dio->blocks_available -= this_chunk_blocks; |
915 | next_block: |
916 | if (dio->block_in_file > dio->final_block_in_request) |
917 | BUG(); |
918 | if (dio->block_in_file == dio->final_block_in_request) |
919 | break; |
920 | } |
921 | |
922 | /* Drop the ref which was taken in get_user_pages() */ |
923 | page_cache_release(page); |
924 | block_in_page = 0; |
925 | } |
926 | out: |
927 | return ret; |
928 | } |
929 | |
930 | /* |
931 | * Releases both i_sem and i_alloc_sem |
932 | */ |
933 | static ssize_t |
934 | direct_io_worker(int rw, struct kiocb *iocb, struct inode *inode, |
935 | const struct iovec *iov, loff_t offset, unsigned long nr_segs, |
936 | unsigned blkbits, get_blocks_t get_blocks, dio_iodone_t end_io, |
937 | struct dio *dio) |
938 | { |
939 | unsigned long user_addr; |
940 | int seg; |
941 | ssize_t ret = 0; |
942 | ssize_t ret2; |
943 | size_t bytes; |
944 | |
945 | dio->bio = NULL; |
946 | dio->inode = inode; |
947 | dio->rw = rw; |
948 | dio->blkbits = blkbits; |
949 | dio->blkfactor = inode->i_blkbits - blkbits; |
950 | dio->start_zero_done = 0; |
951 | dio->size = 0; |
952 | dio->block_in_file = offset >> blkbits; |
953 | dio->blocks_available = 0; |
954 | dio->cur_page = NULL; |
955 | |
956 | dio->boundary = 0; |
957 | dio->reap_counter = 0; |
958 | dio->get_blocks = get_blocks; |
959 | dio->end_io = end_io; |
960 | dio->map_bh.b_private = NULL; |
961 | dio->final_block_in_bio = -1; |
962 | dio->next_block_for_io = -1; |
963 | |
964 | dio->page_errors = 0; |
965 | dio->result = 0; |
966 | dio->iocb = iocb; |
967 | dio->i_size = i_size_read(inode); |
968 | |
969 | /* |
970 | * BIO completion state. |
971 | * |
972 | * ->bio_count starts out at one, and we decrement it to zero after all |
973 | * BIOs are submitted. This to avoid the situation where a really fast |
974 | * (or synchronous) device could take the count to zero while we're |
975 | * still submitting BIOs. |
976 | */ |
977 | dio->bio_count = 1; |
978 | dio->bios_in_flight = 0; |
979 | spin_lock_init(&dio->bio_lock); |
980 | dio->bio_list = NULL; |
981 | dio->waiter = NULL; |
982 | |
983 | /* |
984 | * In case of non-aligned buffers, we may need 2 more |
985 | * pages since we need to zero out first and last block. |
986 | */ |
987 | if (unlikely(dio->blkfactor)) |
988 | dio->pages_in_io = 2; |
989 | else |
990 | dio->pages_in_io = 0; |
991 | |
992 | for (seg = 0; seg < nr_segs; seg++) { |
993 | user_addr = (unsigned long)iov[seg].iov_base; |
994 | dio->pages_in_io += |
995 | ((user_addr+iov[seg].iov_len +PAGE_SIZE-1)/PAGE_SIZE |
996 | - user_addr/PAGE_SIZE); |
997 | } |
998 | |
999 | for (seg = 0; seg < nr_segs; seg++) { |
1000 | user_addr = (unsigned long)iov[seg].iov_base; |
1001 | dio->size += bytes = iov[seg].iov_len; |
1002 | |
1003 | /* Index into the first page of the first block */ |
1004 | dio->first_block_in_page = (user_addr & ~PAGE_MASK) >> blkbits; |
1005 | dio->final_block_in_request = dio->block_in_file + |
1006 | (bytes >> blkbits); |
1007 | /* Page fetching state */ |
1008 | dio->head = 0; |
1009 | dio->tail = 0; |
1010 | dio->curr_page = 0; |
1011 | |
1012 | dio->total_pages = 0; |
1013 | if (user_addr & (PAGE_SIZE-1)) { |
1014 | dio->total_pages++; |
1015 | bytes -= PAGE_SIZE - (user_addr & (PAGE_SIZE - 1)); |
1016 | } |
1017 | dio->total_pages += (bytes + PAGE_SIZE - 1) / PAGE_SIZE; |
1018 | dio->curr_user_address = user_addr; |
1019 | |
1020 | ret = do_direct_IO(dio); |
1021 | |
1022 | dio->result += iov[seg].iov_len - |
1023 | ((dio->final_block_in_request - dio->block_in_file) << |
1024 | blkbits); |
1025 | |
1026 | if (ret) { |
1027 | dio_cleanup(dio); |
1028 | break; |
1029 | } |
1030 | } /* end iovec loop */ |
1031 | |
1032 | if (ret == -ENOTBLK && rw == WRITE) { |
1033 | /* |
1034 | * The remaining part of the request will be |
1035 | * be handled by buffered I/O when we return |
1036 | */ |
1037 | ret = 0; |
1038 | } |
1039 | /* |
1040 | * There may be some unwritten disk at the end of a part-written |
1041 | * fs-block-sized block. Go zero that now. |
1042 | */ |
1043 | dio_zero_block(dio, 1); |
1044 | |
1045 | if (dio->cur_page) { |
1046 | ret2 = dio_send_cur_page(dio); |
1047 | if (ret == 0) |
1048 | ret = ret2; |
1049 | page_cache_release(dio->cur_page); |
1050 | dio->cur_page = NULL; |
1051 | } |
1052 | if (dio->bio) |
1053 | dio_bio_submit(dio); |
1054 | |
1055 | /* |
1056 | * It is possible that, we return short IO due to end of file. |
1057 | * In that case, we need to release all the pages we got hold on. |
1058 | */ |
1059 | dio_cleanup(dio); |
1060 | |
1061 | /* |
1062 | * All block lookups have been performed. For READ requests |
1063 | * we can let i_sem go now that its achieved its purpose |
1064 | * of protecting us from looking up uninitialized blocks. |
1065 | */ |
1066 | if ((rw == READ) && (dio->lock_type == DIO_LOCKING)) |
1067 | up(&dio->inode->i_sem); |
1068 | |
1069 | /* |
1070 | * OK, all BIOs are submitted, so we can decrement bio_count to truly |
1071 | * reflect the number of to-be-processed BIOs. |
1072 | */ |
1073 | if (dio->is_async) { |
1074 | int should_wait = 0; |
1075 | |
1076 | if (dio->result < dio->size && rw == WRITE) { |
1077 | dio->waiter = current; |
1078 | should_wait = 1; |
1079 | } |
1080 | if (ret == 0) |
1081 | ret = dio->result; |
1082 | finished_one_bio(dio); /* This can free the dio */ |
1083 | blk_run_address_space(inode->i_mapping); |
1084 | if (should_wait) { |
1085 | unsigned long flags; |
1086 | /* |
1087 | * Wait for already issued I/O to drain out and |
1088 | * release its references to user-space pages |
1089 | * before returning to fallback on buffered I/O |
1090 | */ |
1091 | |
1092 | spin_lock_irqsave(&dio->bio_lock, flags); |
1093 | set_current_state(TASK_UNINTERRUPTIBLE); |
1094 | while (dio->bio_count) { |
1095 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
1096 | io_schedule(); |
1097 | spin_lock_irqsave(&dio->bio_lock, flags); |
1098 | set_current_state(TASK_UNINTERRUPTIBLE); |
1099 | } |
1100 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
1101 | set_current_state(TASK_RUNNING); |
1102 | kfree(dio); |
1103 | } |
1104 | } else { |
1105 | ssize_t transferred = 0; |
1106 | |
1107 | finished_one_bio(dio); |
1108 | ret2 = dio_await_completion(dio); |
1109 | if (ret == 0) |
1110 | ret = ret2; |
1111 | if (ret == 0) |
1112 | ret = dio->page_errors; |
1113 | if (dio->result) { |
1114 | loff_t i_size = i_size_read(inode); |
1115 | |
1116 | transferred = dio->result; |
1117 | /* |
1118 | * Adjust the return value if the read crossed a |
1119 | * non-block-aligned EOF. |
1120 | */ |
1121 | if (rw == READ && (offset + transferred > i_size)) |
1122 | transferred = i_size - offset; |
1123 | } |
1124 | dio_complete(dio, offset, transferred); |
1125 | if (ret == 0) |
1126 | ret = transferred; |
1127 | |
1128 | /* We could have also come here on an AIO file extend */ |
1129 | if (!is_sync_kiocb(iocb) && rw == WRITE && |
1130 | ret >= 0 && dio->result == dio->size) |
1131 | /* |
1132 | * For AIO writes where we have completed the |
1133 | * i/o, we have to mark the the aio complete. |
1134 | */ |
1135 | aio_complete(iocb, ret, 0); |
1136 | kfree(dio); |
1137 | } |
1138 | return ret; |
1139 | } |
1140 | |
1141 | /* |
1142 | * This is a library function for use by filesystem drivers. |
1143 | * The locking rules are governed by the dio_lock_type parameter. |
1144 | * |
1145 | * DIO_NO_LOCKING (no locking, for raw block device access) |
1146 | * For writes, i_sem is not held on entry; it is never taken. |
1147 | * |
1148 | * DIO_LOCKING (simple locking for regular files) |
1149 | * For writes we are called under i_sem and return with i_sem held, even though |
1150 | * it is internally dropped. |
1151 | * For reads, i_sem is not held on entry, but it is taken and dropped before |
1152 | * returning. |
1153 | * |
1154 | * DIO_OWN_LOCKING (filesystem provides synchronisation and handling of |
1155 | * uninitialised data, allowing parallel direct readers and writers) |
1156 | * For writes we are called without i_sem, return without it, never touch it. |
1157 | * For reads, i_sem is held on entry and will be released before returning. |
1158 | * |
1159 | * Additional i_alloc_sem locking requirements described inline below. |
1160 | */ |
1161 | ssize_t |
1162 | __blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode, |
1163 | struct block_device *bdev, const struct iovec *iov, loff_t offset, |
1164 | unsigned long nr_segs, get_blocks_t get_blocks, dio_iodone_t end_io, |
1165 | int dio_lock_type) |
1166 | { |
1167 | int seg; |
1168 | size_t size; |
1169 | unsigned long addr; |
1170 | unsigned blkbits = inode->i_blkbits; |
1171 | unsigned bdev_blkbits = 0; |
1172 | unsigned blocksize_mask = (1 << blkbits) - 1; |
1173 | ssize_t retval = -EINVAL; |
1174 | loff_t end = offset; |
1175 | struct dio *dio; |
1176 | int reader_with_isem = (rw == READ && dio_lock_type == DIO_OWN_LOCKING); |
1177 | |
1178 | if (rw & WRITE) |
1179 | current->flags |= PF_SYNCWRITE; |
1180 | |
1181 | if (bdev) |
1182 | bdev_blkbits = blksize_bits(bdev_hardsect_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 | /* |
1212 | * For block device access DIO_NO_LOCKING is used, |
1213 | * neither readers nor writers do any locking at all |
1214 | * For regular files using DIO_LOCKING, |
1215 | * readers need to grab i_sem and i_alloc_sem |
1216 | * writers need to grab i_alloc_sem only (i_sem is already held) |
1217 | * For regular files using DIO_OWN_LOCKING, |
1218 | * neither readers nor writers take any locks here |
1219 | * (i_sem is already held and release for writers here) |
1220 | */ |
1221 | dio->lock_type = dio_lock_type; |
1222 | if (dio_lock_type != DIO_NO_LOCKING) { |
1223 | /* watch out for a 0 len io from a tricksy fs */ |
1224 | if (rw == READ && end > offset) { |
1225 | struct address_space *mapping; |
1226 | |
1227 | mapping = iocb->ki_filp->f_mapping; |
1228 | if (dio_lock_type != DIO_OWN_LOCKING) { |
1229 | down(&inode->i_sem); |
1230 | reader_with_isem = 1; |
1231 | } |
1232 | |
1233 | retval = filemap_write_and_wait_range(mapping, offset, |
1234 | end - 1); |
1235 | if (retval) { |
1236 | kfree(dio); |
1237 | goto out; |
1238 | } |
1239 | |
1240 | if (dio_lock_type == DIO_OWN_LOCKING) { |
1241 | up(&inode->i_sem); |
1242 | reader_with_isem = 0; |
1243 | } |
1244 | } |
1245 | |
1246 | if (dio_lock_type == DIO_LOCKING) |
1247 | down_read(&inode->i_alloc_sem); |
1248 | } |
1249 | |
1250 | /* |
1251 | * For file extending writes updating i_size before data |
1252 | * writeouts complete can expose uninitialized blocks. So |
1253 | * even for AIO, we need to wait for i/o to complete before |
1254 | * returning in this case. |
1255 | */ |
1256 | dio->is_async = !is_sync_kiocb(iocb) && !((rw == WRITE) && |
1257 | (end > i_size_read(inode))); |
1258 | |
1259 | retval = direct_io_worker(rw, iocb, inode, iov, offset, |
1260 | nr_segs, blkbits, get_blocks, end_io, dio); |
1261 | |
1262 | if (rw == READ && dio_lock_type == DIO_LOCKING) |
1263 | reader_with_isem = 0; |
1264 | |
1265 | out: |
1266 | if (reader_with_isem) |
1267 | up(&inode->i_sem); |
1268 | if (rw & WRITE) |
1269 | current->flags &= ~PF_SYNCWRITE; |
1270 | return retval; |
1271 | } |
1272 | EXPORT_SYMBOL(__blockdev_direct_IO); |