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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * fs/direct-io.c | |
4 | * | |
5 | * Copyright (C) 2002, Linus Torvalds. | |
6 | * | |
7 | * O_DIRECT | |
8 | * | |
e1f8e874 | 9 | * 04Jul2002 Andrew Morton |
1da177e4 LT |
10 | * Initial version |
11 | * 11Sep2002 janetinc@us.ibm.com | |
12 | * added readv/writev support. | |
e1f8e874 | 13 | * 29Oct2002 Andrew Morton |
1da177e4 LT |
14 | * rewrote bio_add_page() support. |
15 | * 30Oct2002 pbadari@us.ibm.com | |
16 | * added support for non-aligned IO. | |
17 | * 06Nov2002 pbadari@us.ibm.com | |
18 | * added asynchronous IO support. | |
19 | * 21Jul2003 nathans@sgi.com | |
20 | * added IO completion notifier. | |
21 | */ | |
22 | ||
23 | #include <linux/kernel.h> | |
24 | #include <linux/module.h> | |
25 | #include <linux/types.h> | |
26 | #include <linux/fs.h> | |
27 | #include <linux/mm.h> | |
28 | #include <linux/slab.h> | |
29 | #include <linux/highmem.h> | |
30 | #include <linux/pagemap.h> | |
98c4d57d | 31 | #include <linux/task_io_accounting_ops.h> |
1da177e4 LT |
32 | #include <linux/bio.h> |
33 | #include <linux/wait.h> | |
34 | #include <linux/err.h> | |
35 | #include <linux/blkdev.h> | |
36 | #include <linux/buffer_head.h> | |
37 | #include <linux/rwsem.h> | |
38 | #include <linux/uio.h> | |
60063497 | 39 | #include <linux/atomic.h> |
65dd2aa9 | 40 | #include <linux/prefetch.h> |
1da177e4 LT |
41 | |
42 | /* | |
43 | * How many user pages to map in one call to get_user_pages(). This determines | |
cde1ecb3 | 44 | * the size of a structure in the slab cache |
1da177e4 LT |
45 | */ |
46 | #define DIO_PAGES 64 | |
47 | ||
ffe51f01 LC |
48 | /* |
49 | * Flags for dio_complete() | |
50 | */ | |
51 | #define DIO_COMPLETE_ASYNC 0x01 /* This is async IO */ | |
52 | #define DIO_COMPLETE_INVALIDATE 0x02 /* Can invalidate pages */ | |
53 | ||
1da177e4 LT |
54 | /* |
55 | * This code generally works in units of "dio_blocks". A dio_block is | |
56 | * somewhere between the hard sector size and the filesystem block size. it | |
57 | * is determined on a per-invocation basis. When talking to the filesystem | |
58 | * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity | |
59 | * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted | |
60 | * to bio_block quantities by shifting left by blkfactor. | |
61 | * | |
62 | * If blkfactor is zero then the user's request was aligned to the filesystem's | |
63 | * blocksize. | |
1da177e4 LT |
64 | */ |
65 | ||
eb28be2b AK |
66 | /* dio_state only used in the submission path */ |
67 | ||
68 | struct dio_submit { | |
1da177e4 | 69 | struct bio *bio; /* bio under assembly */ |
1da177e4 LT |
70 | unsigned blkbits; /* doesn't change */ |
71 | unsigned blkfactor; /* When we're using an alignment which | |
72 | is finer than the filesystem's soft | |
73 | blocksize, this specifies how much | |
74 | finer. blkfactor=2 means 1/4-block | |
75 | alignment. Does not change */ | |
76 | unsigned start_zero_done; /* flag: sub-blocksize zeroing has | |
77 | been performed at the start of a | |
78 | write */ | |
79 | int pages_in_io; /* approximate total IO pages */ | |
1da177e4 LT |
80 | sector_t block_in_file; /* Current offset into the underlying |
81 | file in dio_block units. */ | |
82 | unsigned blocks_available; /* At block_in_file. changes */ | |
0dc2bc49 | 83 | int reap_counter; /* rate limit reaping */ |
1da177e4 | 84 | sector_t final_block_in_request;/* doesn't change */ |
1da177e4 | 85 | int boundary; /* prev block is at a boundary */ |
1d8fa7a2 | 86 | get_block_t *get_block; /* block mapping function */ |
facd07b0 | 87 | dio_submit_t *submit_io; /* IO submition function */ |
eb28be2b | 88 | |
facd07b0 | 89 | loff_t logical_offset_in_bio; /* current first logical block in bio */ |
1da177e4 LT |
90 | sector_t final_block_in_bio; /* current final block in bio + 1 */ |
91 | sector_t next_block_for_io; /* next block to be put under IO, | |
92 | in dio_blocks units */ | |
1da177e4 LT |
93 | |
94 | /* | |
95 | * Deferred addition of a page to the dio. These variables are | |
96 | * private to dio_send_cur_page(), submit_page_section() and | |
97 | * dio_bio_add_page(). | |
98 | */ | |
99 | struct page *cur_page; /* The page */ | |
100 | unsigned cur_page_offset; /* Offset into it, in bytes */ | |
101 | unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ | |
102 | sector_t cur_page_block; /* Where it starts */ | |
facd07b0 | 103 | loff_t cur_page_fs_offset; /* Offset in file */ |
1da177e4 | 104 | |
7b2c99d1 | 105 | struct iov_iter *iter; |
1da177e4 LT |
106 | /* |
107 | * Page queue. These variables belong to dio_refill_pages() and | |
108 | * dio_get_page(). | |
109 | */ | |
1da177e4 LT |
110 | unsigned head; /* next page to process */ |
111 | unsigned tail; /* last valid page + 1 */ | |
7b2c99d1 | 112 | size_t from, to; |
eb28be2b AK |
113 | }; |
114 | ||
115 | /* dio_state communicated between submission path and end_io */ | |
116 | struct dio { | |
117 | int flags; /* doesn't change */ | |
8a4c1e42 MC |
118 | int op; |
119 | int op_flags; | |
15c4f638 | 120 | blk_qc_t bio_cookie; |
74d46992 | 121 | struct gendisk *bio_disk; |
0dc2bc49 | 122 | struct inode *inode; |
eb28be2b AK |
123 | loff_t i_size; /* i_size when submitted */ |
124 | dio_iodone_t *end_io; /* IO completion function */ | |
eb28be2b | 125 | |
18772641 | 126 | void *private; /* copy from map_bh.b_private */ |
eb28be2b AK |
127 | |
128 | /* BIO completion state */ | |
129 | spinlock_t bio_lock; /* protects BIO fields below */ | |
0dc2bc49 AK |
130 | int page_errors; /* errno from get_user_pages() */ |
131 | int is_async; /* is IO async ? */ | |
7b7a8665 | 132 | bool defer_completion; /* defer AIO completion to workqueue? */ |
53cbf3b1 | 133 | bool should_dirty; /* if pages should be dirtied */ |
0dc2bc49 | 134 | int io_error; /* IO error in completion path */ |
eb28be2b AK |
135 | unsigned long refcount; /* direct_io_worker() and bios */ |
136 | struct bio *bio_list; /* singly linked via bi_private */ | |
137 | struct task_struct *waiter; /* waiting task (NULL if none) */ | |
138 | ||
139 | /* AIO related stuff */ | |
140 | struct kiocb *iocb; /* kiocb */ | |
eb28be2b AK |
141 | ssize_t result; /* IO result */ |
142 | ||
23aee091 JM |
143 | /* |
144 | * pages[] (and any fields placed after it) are not zeroed out at | |
145 | * allocation time. Don't add new fields after pages[] unless you | |
146 | * wish that they not be zeroed. | |
147 | */ | |
7b7a8665 CH |
148 | union { |
149 | struct page *pages[DIO_PAGES]; /* page buffer */ | |
150 | struct work_struct complete_work;/* deferred AIO completion */ | |
151 | }; | |
6e8267f5 AK |
152 | } ____cacheline_aligned_in_smp; |
153 | ||
154 | static struct kmem_cache *dio_cache __read_mostly; | |
1da177e4 LT |
155 | |
156 | /* | |
157 | * How many pages are in the queue? | |
158 | */ | |
eb28be2b | 159 | static inline unsigned dio_pages_present(struct dio_submit *sdio) |
1da177e4 | 160 | { |
eb28be2b | 161 | return sdio->tail - sdio->head; |
1da177e4 LT |
162 | } |
163 | ||
164 | /* | |
165 | * Go grab and pin some userspace pages. Typically we'll get 64 at a time. | |
166 | */ | |
ba253fbf | 167 | static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 168 | { |
7b2c99d1 | 169 | ssize_t ret; |
1da177e4 | 170 | |
2c80929c | 171 | ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES, |
7b2c99d1 | 172 | &sdio->from); |
1da177e4 | 173 | |
8a4c1e42 | 174 | if (ret < 0 && sdio->blocks_available && (dio->op == REQ_OP_WRITE)) { |
557ed1fa | 175 | struct page *page = ZERO_PAGE(0); |
1da177e4 LT |
176 | /* |
177 | * A memory fault, but the filesystem has some outstanding | |
178 | * mapped blocks. We need to use those blocks up to avoid | |
179 | * leaking stale data in the file. | |
180 | */ | |
181 | if (dio->page_errors == 0) | |
182 | dio->page_errors = ret; | |
09cbfeaf | 183 | get_page(page); |
b5810039 | 184 | dio->pages[0] = page; |
eb28be2b AK |
185 | sdio->head = 0; |
186 | sdio->tail = 1; | |
7b2c99d1 AV |
187 | sdio->from = 0; |
188 | sdio->to = PAGE_SIZE; | |
189 | return 0; | |
1da177e4 LT |
190 | } |
191 | ||
192 | if (ret >= 0) { | |
7b2c99d1 AV |
193 | iov_iter_advance(sdio->iter, ret); |
194 | ret += sdio->from; | |
eb28be2b | 195 | sdio->head = 0; |
7b2c99d1 AV |
196 | sdio->tail = (ret + PAGE_SIZE - 1) / PAGE_SIZE; |
197 | sdio->to = ((ret - 1) & (PAGE_SIZE - 1)) + 1; | |
198 | return 0; | |
1da177e4 | 199 | } |
1da177e4 LT |
200 | return ret; |
201 | } | |
202 | ||
203 | /* | |
204 | * Get another userspace page. Returns an ERR_PTR on error. Pages are | |
205 | * buffered inside the dio so that we can call get_user_pages() against a | |
206 | * decent number of pages, less frequently. To provide nicer use of the | |
207 | * L1 cache. | |
208 | */ | |
ba253fbf | 209 | static inline struct page *dio_get_page(struct dio *dio, |
6fcc5420 | 210 | struct dio_submit *sdio) |
1da177e4 | 211 | { |
eb28be2b | 212 | if (dio_pages_present(sdio) == 0) { |
1da177e4 LT |
213 | int ret; |
214 | ||
eb28be2b | 215 | ret = dio_refill_pages(dio, sdio); |
1da177e4 LT |
216 | if (ret) |
217 | return ERR_PTR(ret); | |
eb28be2b | 218 | BUG_ON(dio_pages_present(sdio) == 0); |
1da177e4 | 219 | } |
6fcc5420 | 220 | return dio->pages[sdio->head]; |
1da177e4 LT |
221 | } |
222 | ||
c70d868f | 223 | /* |
6d544bb4 | 224 | * dio_complete() - called when all DIO BIO I/O has been completed |
6d544bb4 | 225 | * |
7b7a8665 CH |
226 | * This drops i_dio_count, lets interested parties know that a DIO operation |
227 | * has completed, and calculates the resulting return code for the operation. | |
6d544bb4 ZB |
228 | * |
229 | * It lets the filesystem know if it registered an interest earlier via | |
230 | * get_block. Pass the private field of the map buffer_head so that | |
231 | * filesystems can use it to hold additional state between get_block calls and | |
232 | * dio_complete. | |
1da177e4 | 233 | */ |
ffe51f01 | 234 | static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags) |
1da177e4 | 235 | { |
716b9bc0 | 236 | loff_t offset = dio->iocb->ki_pos; |
6d544bb4 | 237 | ssize_t transferred = 0; |
332391a9 | 238 | int err; |
6d544bb4 | 239 | |
8459d86a ZB |
240 | /* |
241 | * AIO submission can race with bio completion to get here while | |
242 | * expecting to have the last io completed by bio completion. | |
243 | * In that case -EIOCBQUEUED is in fact not an error we want | |
244 | * to preserve through this call. | |
245 | */ | |
246 | if (ret == -EIOCBQUEUED) | |
247 | ret = 0; | |
248 | ||
6d544bb4 ZB |
249 | if (dio->result) { |
250 | transferred = dio->result; | |
251 | ||
252 | /* Check for short read case */ | |
8a4c1e42 MC |
253 | if ((dio->op == REQ_OP_READ) && |
254 | ((offset + transferred) > dio->i_size)) | |
6d544bb4 | 255 | transferred = dio->i_size - offset; |
4038acdb AV |
256 | /* ignore EFAULT if some IO has been done */ |
257 | if (unlikely(ret == -EFAULT) && transferred) | |
258 | ret = 0; | |
6d544bb4 ZB |
259 | } |
260 | ||
6d544bb4 ZB |
261 | if (ret == 0) |
262 | ret = dio->page_errors; | |
263 | if (ret == 0) | |
264 | ret = dio->io_error; | |
265 | if (ret == 0) | |
266 | ret = transferred; | |
267 | ||
5e25c269 EG |
268 | if (dio->end_io) { |
269 | // XXX: ki_pos?? | |
270 | err = dio->end_io(dio->iocb, offset, ret, dio->private); | |
271 | if (err) | |
272 | ret = err; | |
273 | } | |
274 | ||
332391a9 LC |
275 | /* |
276 | * Try again to invalidate clean pages which might have been cached by | |
277 | * non-direct readahead, or faulted in by get_user_pages() if the source | |
278 | * of the write was an mmap'ed region of the file we're writing. Either | |
279 | * one is a pretty crazy thing to do, so we don't support it 100%. If | |
280 | * this invalidation fails, tough, the write still worked... | |
5e25c269 EG |
281 | * |
282 | * And this page cache invalidation has to be after dio->end_io(), as | |
283 | * some filesystems convert unwritten extents to real allocations in | |
284 | * end_io() when necessary, otherwise a racing buffer read would cache | |
285 | * zeros from unwritten extents. | |
332391a9 | 286 | */ |
ffe51f01 LC |
287 | if (flags & DIO_COMPLETE_INVALIDATE && |
288 | ret > 0 && dio->op == REQ_OP_WRITE && | |
332391a9 LC |
289 | dio->inode->i_mapping->nrpages) { |
290 | err = invalidate_inode_pages2_range(dio->inode->i_mapping, | |
291 | offset >> PAGE_SHIFT, | |
292 | (offset + ret - 1) >> PAGE_SHIFT); | |
5a9d929d DW |
293 | if (err) |
294 | dio_warn_stale_pagecache(dio->iocb->ki_filp); | |
332391a9 LC |
295 | } |
296 | ||
ce3077ee | 297 | inode_dio_end(dio->inode); |
fe0f07d0 | 298 | |
ffe51f01 | 299 | if (flags & DIO_COMPLETE_ASYNC) { |
e2592217 CH |
300 | /* |
301 | * generic_write_sync expects ki_pos to have been updated | |
302 | * already, but the submission path only does this for | |
303 | * synchronous I/O. | |
304 | */ | |
305 | dio->iocb->ki_pos += transferred; | |
02afc27f | 306 | |
41e817bc MH |
307 | if (ret > 0 && dio->op == REQ_OP_WRITE) |
308 | ret = generic_write_sync(dio->iocb, ret); | |
04b2fa9f | 309 | dio->iocb->ki_complete(dio->iocb, ret, 0); |
02afc27f | 310 | } |
40e2e973 | 311 | |
7b7a8665 | 312 | kmem_cache_free(dio_cache, dio); |
6d544bb4 | 313 | return ret; |
1da177e4 LT |
314 | } |
315 | ||
7b7a8665 CH |
316 | static void dio_aio_complete_work(struct work_struct *work) |
317 | { | |
318 | struct dio *dio = container_of(work, struct dio, complete_work); | |
319 | ||
ffe51f01 | 320 | dio_complete(dio, 0, DIO_COMPLETE_ASYNC | DIO_COMPLETE_INVALIDATE); |
7b7a8665 CH |
321 | } |
322 | ||
4e4cbee9 | 323 | static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio); |
7b7a8665 | 324 | |
1da177e4 LT |
325 | /* |
326 | * Asynchronous IO callback. | |
327 | */ | |
4246a0b6 | 328 | static void dio_bio_end_aio(struct bio *bio) |
1da177e4 LT |
329 | { |
330 | struct dio *dio = bio->bi_private; | |
5eb6c7a2 ZB |
331 | unsigned long remaining; |
332 | unsigned long flags; | |
332391a9 | 333 | bool defer_completion = false; |
1da177e4 | 334 | |
1da177e4 LT |
335 | /* cleanup the bio */ |
336 | dio_bio_complete(dio, bio); | |
0273201e | 337 | |
5eb6c7a2 ZB |
338 | spin_lock_irqsave(&dio->bio_lock, flags); |
339 | remaining = --dio->refcount; | |
340 | if (remaining == 1 && dio->waiter) | |
20258b2b | 341 | wake_up_process(dio->waiter); |
5eb6c7a2 | 342 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
20258b2b | 343 | |
8459d86a | 344 | if (remaining == 0) { |
332391a9 LC |
345 | /* |
346 | * Defer completion when defer_completion is set or | |
347 | * when the inode has pages mapped and this is AIO write. | |
348 | * We need to invalidate those pages because there is a | |
349 | * chance they contain stale data in the case buffered IO | |
350 | * went in between AIO submission and completion into the | |
351 | * same region. | |
352 | */ | |
353 | if (dio->result) | |
354 | defer_completion = dio->defer_completion || | |
355 | (dio->op == REQ_OP_WRITE && | |
356 | dio->inode->i_mapping->nrpages); | |
357 | if (defer_completion) { | |
7b7a8665 CH |
358 | INIT_WORK(&dio->complete_work, dio_aio_complete_work); |
359 | queue_work(dio->inode->i_sb->s_dio_done_wq, | |
360 | &dio->complete_work); | |
361 | } else { | |
ffe51f01 | 362 | dio_complete(dio, 0, DIO_COMPLETE_ASYNC); |
7b7a8665 | 363 | } |
8459d86a | 364 | } |
1da177e4 LT |
365 | } |
366 | ||
367 | /* | |
368 | * The BIO completion handler simply queues the BIO up for the process-context | |
369 | * handler. | |
370 | * | |
371 | * During I/O bi_private points at the dio. After I/O, bi_private is used to | |
372 | * implement a singly-linked list of completed BIOs, at dio->bio_list. | |
373 | */ | |
4246a0b6 | 374 | static void dio_bio_end_io(struct bio *bio) |
1da177e4 LT |
375 | { |
376 | struct dio *dio = bio->bi_private; | |
377 | unsigned long flags; | |
378 | ||
1da177e4 LT |
379 | spin_lock_irqsave(&dio->bio_lock, flags); |
380 | bio->bi_private = dio->bio_list; | |
381 | dio->bio_list = bio; | |
5eb6c7a2 | 382 | if (--dio->refcount == 1 && dio->waiter) |
1da177e4 LT |
383 | wake_up_process(dio->waiter); |
384 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
1da177e4 LT |
385 | } |
386 | ||
facd07b0 JB |
387 | /** |
388 | * dio_end_io - handle the end io action for the given bio | |
389 | * @bio: The direct io bio thats being completed | |
facd07b0 JB |
390 | * |
391 | * This is meant to be called by any filesystem that uses their own dio_submit_t | |
392 | * so that the DIO specific endio actions are dealt with after the filesystem | |
393 | * has done it's completion work. | |
394 | */ | |
4055351c | 395 | void dio_end_io(struct bio *bio) |
facd07b0 JB |
396 | { |
397 | struct dio *dio = bio->bi_private; | |
398 | ||
399 | if (dio->is_async) | |
4246a0b6 | 400 | dio_bio_end_aio(bio); |
facd07b0 | 401 | else |
4246a0b6 | 402 | dio_bio_end_io(bio); |
facd07b0 JB |
403 | } |
404 | EXPORT_SYMBOL_GPL(dio_end_io); | |
405 | ||
ba253fbf | 406 | static inline void |
eb28be2b AK |
407 | dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, |
408 | struct block_device *bdev, | |
409 | sector_t first_sector, int nr_vecs) | |
1da177e4 LT |
410 | { |
411 | struct bio *bio; | |
412 | ||
20d9600c | 413 | /* |
0eb0b63c CH |
414 | * bio_alloc() is guaranteed to return a bio when allowed to sleep and |
415 | * we request a valid number of vectors. | |
20d9600c | 416 | */ |
1da177e4 | 417 | bio = bio_alloc(GFP_KERNEL, nr_vecs); |
1da177e4 | 418 | |
74d46992 | 419 | bio_set_dev(bio, bdev); |
4f024f37 | 420 | bio->bi_iter.bi_sector = first_sector; |
8a4c1e42 | 421 | bio_set_op_attrs(bio, dio->op, dio->op_flags); |
1da177e4 LT |
422 | if (dio->is_async) |
423 | bio->bi_end_io = dio_bio_end_aio; | |
424 | else | |
425 | bio->bi_end_io = dio_bio_end_io; | |
426 | ||
45d06cf7 JA |
427 | bio->bi_write_hint = dio->iocb->ki_hint; |
428 | ||
eb28be2b AK |
429 | sdio->bio = bio; |
430 | sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; | |
1da177e4 LT |
431 | } |
432 | ||
433 | /* | |
434 | * In the AIO read case we speculatively dirty the pages before starting IO. | |
435 | * During IO completion, any of these pages which happen to have been written | |
436 | * back will be redirtied by bio_check_pages_dirty(). | |
0273201e ZB |
437 | * |
438 | * bios hold a dio reference between submit_bio and ->end_io. | |
1da177e4 | 439 | */ |
ba253fbf | 440 | static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 441 | { |
eb28be2b | 442 | struct bio *bio = sdio->bio; |
5eb6c7a2 | 443 | unsigned long flags; |
1da177e4 LT |
444 | |
445 | bio->bi_private = dio; | |
5eb6c7a2 ZB |
446 | |
447 | spin_lock_irqsave(&dio->bio_lock, flags); | |
448 | dio->refcount++; | |
449 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
450 | ||
8a4c1e42 | 451 | if (dio->is_async && dio->op == REQ_OP_READ && dio->should_dirty) |
1da177e4 | 452 | bio_set_pages_dirty(bio); |
5eb6c7a2 | 453 | |
74d46992 | 454 | dio->bio_disk = bio->bi_disk; |
c1c53460 | 455 | |
15c4f638 | 456 | if (sdio->submit_io) { |
8a4c1e42 | 457 | sdio->submit_io(bio, dio->inode, sdio->logical_offset_in_bio); |
15c4f638 | 458 | dio->bio_cookie = BLK_QC_T_NONE; |
c1c53460 | 459 | } else |
4e49ea4a | 460 | dio->bio_cookie = submit_bio(bio); |
1da177e4 | 461 | |
eb28be2b AK |
462 | sdio->bio = NULL; |
463 | sdio->boundary = 0; | |
464 | sdio->logical_offset_in_bio = 0; | |
1da177e4 LT |
465 | } |
466 | ||
467 | /* | |
468 | * Release any resources in case of a failure | |
469 | */ | |
ba253fbf | 470 | static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 471 | { |
7b2c99d1 | 472 | while (sdio->head < sdio->tail) |
09cbfeaf | 473 | put_page(dio->pages[sdio->head++]); |
1da177e4 LT |
474 | } |
475 | ||
476 | /* | |
0273201e ZB |
477 | * Wait for the next BIO to complete. Remove it and return it. NULL is |
478 | * returned once all BIOs have been completed. This must only be called once | |
479 | * all bios have been issued so that dio->refcount can only decrease. This | |
480 | * requires that that the caller hold a reference on the dio. | |
1da177e4 LT |
481 | */ |
482 | static struct bio *dio_await_one(struct dio *dio) | |
483 | { | |
484 | unsigned long flags; | |
0273201e | 485 | struct bio *bio = NULL; |
1da177e4 LT |
486 | |
487 | spin_lock_irqsave(&dio->bio_lock, flags); | |
5eb6c7a2 ZB |
488 | |
489 | /* | |
490 | * Wait as long as the list is empty and there are bios in flight. bio | |
491 | * completion drops the count, maybe adds to the list, and wakes while | |
492 | * holding the bio_lock so we don't need set_current_state()'s barrier | |
493 | * and can call it after testing our condition. | |
494 | */ | |
495 | while (dio->refcount > 1 && dio->bio_list == NULL) { | |
496 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
497 | dio->waiter = current; | |
498 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
c43c83a2 | 499 | if (!(dio->iocb->ki_flags & IOCB_HIPRI) || |
0a1b8b87 | 500 | !blk_poll(dio->bio_disk->queue, dio->bio_cookie, true)) |
15c4f638 | 501 | io_schedule(); |
5eb6c7a2 ZB |
502 | /* wake up sets us TASK_RUNNING */ |
503 | spin_lock_irqsave(&dio->bio_lock, flags); | |
504 | dio->waiter = NULL; | |
1da177e4 | 505 | } |
0273201e ZB |
506 | if (dio->bio_list) { |
507 | bio = dio->bio_list; | |
508 | dio->bio_list = bio->bi_private; | |
509 | } | |
1da177e4 LT |
510 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
511 | return bio; | |
512 | } | |
513 | ||
514 | /* | |
515 | * Process one completed BIO. No locks are held. | |
516 | */ | |
4e4cbee9 | 517 | static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio) |
1da177e4 | 518 | { |
4e4cbee9 | 519 | blk_status_t err = bio->bi_status; |
d7c8aa85 | 520 | bool should_dirty = dio->op == REQ_OP_READ && dio->should_dirty; |
1da177e4 | 521 | |
03a07c92 GR |
522 | if (err) { |
523 | if (err == BLK_STS_AGAIN && (bio->bi_opf & REQ_NOWAIT)) | |
524 | dio->io_error = -EAGAIN; | |
525 | else | |
526 | dio->io_error = -EIO; | |
527 | } | |
1da177e4 | 528 | |
d7c8aa85 | 529 | if (dio->is_async && should_dirty) { |
7ddc971f | 530 | bio_check_pages_dirty(bio); /* transfers ownership */ |
1da177e4 | 531 | } else { |
d7c8aa85 | 532 | bio_release_pages(bio, should_dirty); |
1da177e4 LT |
533 | bio_put(bio); |
534 | } | |
9b81c842 | 535 | return err; |
1da177e4 LT |
536 | } |
537 | ||
538 | /* | |
0273201e ZB |
539 | * Wait on and process all in-flight BIOs. This must only be called once |
540 | * all bios have been issued so that the refcount can only decrease. | |
541 | * This just waits for all bios to make it through dio_bio_complete. IO | |
beb7dd86 | 542 | * errors are propagated through dio->io_error and should be propagated via |
0273201e | 543 | * dio_complete(). |
1da177e4 | 544 | */ |
6d544bb4 | 545 | static void dio_await_completion(struct dio *dio) |
1da177e4 | 546 | { |
0273201e ZB |
547 | struct bio *bio; |
548 | do { | |
549 | bio = dio_await_one(dio); | |
550 | if (bio) | |
551 | dio_bio_complete(dio, bio); | |
552 | } while (bio); | |
1da177e4 LT |
553 | } |
554 | ||
555 | /* | |
556 | * A really large O_DIRECT read or write can generate a lot of BIOs. So | |
557 | * to keep the memory consumption sane we periodically reap any completed BIOs | |
558 | * during the BIO generation phase. | |
559 | * | |
560 | * This also helps to limit the peak amount of pinned userspace memory. | |
561 | */ | |
ba253fbf | 562 | static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
563 | { |
564 | int ret = 0; | |
565 | ||
eb28be2b | 566 | if (sdio->reap_counter++ >= 64) { |
1da177e4 LT |
567 | while (dio->bio_list) { |
568 | unsigned long flags; | |
569 | struct bio *bio; | |
570 | int ret2; | |
571 | ||
572 | spin_lock_irqsave(&dio->bio_lock, flags); | |
573 | bio = dio->bio_list; | |
574 | dio->bio_list = bio->bi_private; | |
575 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
4e4cbee9 | 576 | ret2 = blk_status_to_errno(dio_bio_complete(dio, bio)); |
1da177e4 LT |
577 | if (ret == 0) |
578 | ret = ret2; | |
579 | } | |
eb28be2b | 580 | sdio->reap_counter = 0; |
1da177e4 LT |
581 | } |
582 | return ret; | |
583 | } | |
584 | ||
7b7a8665 CH |
585 | /* |
586 | * Create workqueue for deferred direct IO completions. We allocate the | |
587 | * workqueue when it's first needed. This avoids creating workqueue for | |
588 | * filesystems that don't need it and also allows us to create the workqueue | |
589 | * late enough so the we can include s_id in the name of the workqueue. | |
590 | */ | |
ec1b8260 | 591 | int sb_init_dio_done_wq(struct super_block *sb) |
7b7a8665 | 592 | { |
45150c43 | 593 | struct workqueue_struct *old; |
7b7a8665 CH |
594 | struct workqueue_struct *wq = alloc_workqueue("dio/%s", |
595 | WQ_MEM_RECLAIM, 0, | |
596 | sb->s_id); | |
597 | if (!wq) | |
598 | return -ENOMEM; | |
599 | /* | |
600 | * This has to be atomic as more DIOs can race to create the workqueue | |
601 | */ | |
45150c43 | 602 | old = cmpxchg(&sb->s_dio_done_wq, NULL, wq); |
7b7a8665 | 603 | /* Someone created workqueue before us? Free ours... */ |
45150c43 | 604 | if (old) |
7b7a8665 CH |
605 | destroy_workqueue(wq); |
606 | return 0; | |
607 | } | |
608 | ||
609 | static int dio_set_defer_completion(struct dio *dio) | |
610 | { | |
611 | struct super_block *sb = dio->inode->i_sb; | |
612 | ||
613 | if (dio->defer_completion) | |
614 | return 0; | |
615 | dio->defer_completion = true; | |
616 | if (!sb->s_dio_done_wq) | |
617 | return sb_init_dio_done_wq(sb); | |
618 | return 0; | |
619 | } | |
620 | ||
1da177e4 LT |
621 | /* |
622 | * Call into the fs to map some more disk blocks. We record the current number | |
eb28be2b | 623 | * of available blocks at sdio->blocks_available. These are in units of the |
93407472 | 624 | * fs blocksize, i_blocksize(inode). |
1da177e4 LT |
625 | * |
626 | * The fs is allowed to map lots of blocks at once. If it wants to do that, | |
627 | * it uses the passed inode-relative block number as the file offset, as usual. | |
628 | * | |
1d8fa7a2 | 629 | * get_block() is passed the number of i_blkbits-sized blocks which direct_io |
1da177e4 LT |
630 | * has remaining to do. The fs should not map more than this number of blocks. |
631 | * | |
632 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to | |
633 | * indicate how much contiguous disk space has been made available at | |
634 | * bh->b_blocknr. | |
635 | * | |
636 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). | |
637 | * This isn't very efficient... | |
638 | * | |
639 | * In the case of filesystem holes: the fs may return an arbitrarily-large | |
640 | * hole by returning an appropriate value in b_size and by clearing | |
641 | * buffer_mapped(). However the direct-io code will only process holes one | |
1d8fa7a2 | 642 | * block at a time - it will repeatedly call get_block() as it walks the hole. |
1da177e4 | 643 | */ |
18772641 AK |
644 | static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, |
645 | struct buffer_head *map_bh) | |
1da177e4 LT |
646 | { |
647 | int ret; | |
1da177e4 | 648 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ |
ae55e1aa | 649 | sector_t fs_endblk; /* Into file, in filesystem-sized blocks */ |
1da177e4 | 650 | unsigned long fs_count; /* Number of filesystem-sized blocks */ |
1da177e4 | 651 | int create; |
ab73857e | 652 | unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor; |
8b9433eb | 653 | loff_t i_size; |
1da177e4 LT |
654 | |
655 | /* | |
656 | * If there was a memory error and we've overwritten all the | |
657 | * mapped blocks then we can now return that memory error | |
658 | */ | |
659 | ret = dio->page_errors; | |
660 | if (ret == 0) { | |
eb28be2b AK |
661 | BUG_ON(sdio->block_in_file >= sdio->final_block_in_request); |
662 | fs_startblk = sdio->block_in_file >> sdio->blkfactor; | |
ae55e1aa TM |
663 | fs_endblk = (sdio->final_block_in_request - 1) >> |
664 | sdio->blkfactor; | |
665 | fs_count = fs_endblk - fs_startblk + 1; | |
1da177e4 | 666 | |
3c674e74 | 667 | map_bh->b_state = 0; |
ab73857e | 668 | map_bh->b_size = fs_count << i_blkbits; |
3c674e74 | 669 | |
5fe878ae | 670 | /* |
9ecd10b7 EG |
671 | * For writes that could fill holes inside i_size on a |
672 | * DIO_SKIP_HOLES filesystem we forbid block creations: only | |
673 | * overwrites are permitted. We will return early to the caller | |
674 | * once we see an unmapped buffer head returned, and the caller | |
675 | * will fall back to buffered I/O. | |
5fe878ae CH |
676 | * |
677 | * Otherwise the decision is left to the get_blocks method, | |
678 | * which may decide to handle it or also return an unmapped | |
679 | * buffer head. | |
680 | */ | |
8a4c1e42 | 681 | create = dio->op == REQ_OP_WRITE; |
5fe878ae | 682 | if (dio->flags & DIO_SKIP_HOLES) { |
8b9433eb EF |
683 | i_size = i_size_read(dio->inode); |
684 | if (i_size && fs_startblk <= (i_size - 1) >> i_blkbits) | |
1da177e4 | 685 | create = 0; |
1da177e4 | 686 | } |
3c674e74 | 687 | |
eb28be2b | 688 | ret = (*sdio->get_block)(dio->inode, fs_startblk, |
1da177e4 | 689 | map_bh, create); |
18772641 AK |
690 | |
691 | /* Store for completion */ | |
692 | dio->private = map_bh->b_private; | |
7b7a8665 CH |
693 | |
694 | if (ret == 0 && buffer_defer_completion(map_bh)) | |
695 | ret = dio_set_defer_completion(dio); | |
1da177e4 LT |
696 | } |
697 | return ret; | |
698 | } | |
699 | ||
700 | /* | |
701 | * There is no bio. Make one now. | |
702 | */ | |
ba253fbf AK |
703 | static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio, |
704 | sector_t start_sector, struct buffer_head *map_bh) | |
1da177e4 LT |
705 | { |
706 | sector_t sector; | |
707 | int ret, nr_pages; | |
708 | ||
eb28be2b | 709 | ret = dio_bio_reap(dio, sdio); |
1da177e4 LT |
710 | if (ret) |
711 | goto out; | |
eb28be2b | 712 | sector = start_sector << (sdio->blkbits - 9); |
b54ffb73 | 713 | nr_pages = min(sdio->pages_in_io, BIO_MAX_PAGES); |
1da177e4 | 714 | BUG_ON(nr_pages <= 0); |
18772641 | 715 | dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages); |
eb28be2b | 716 | sdio->boundary = 0; |
1da177e4 LT |
717 | out: |
718 | return ret; | |
719 | } | |
720 | ||
721 | /* | |
722 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If | |
723 | * that was successful then update final_block_in_bio and take a ref against | |
724 | * the just-added page. | |
725 | * | |
726 | * Return zero on success. Non-zero means the caller needs to start a new BIO. | |
727 | */ | |
ba253fbf | 728 | static inline int dio_bio_add_page(struct dio_submit *sdio) |
1da177e4 LT |
729 | { |
730 | int ret; | |
731 | ||
eb28be2b AK |
732 | ret = bio_add_page(sdio->bio, sdio->cur_page, |
733 | sdio->cur_page_len, sdio->cur_page_offset); | |
734 | if (ret == sdio->cur_page_len) { | |
1da177e4 LT |
735 | /* |
736 | * Decrement count only, if we are done with this page | |
737 | */ | |
eb28be2b AK |
738 | if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE) |
739 | sdio->pages_in_io--; | |
09cbfeaf | 740 | get_page(sdio->cur_page); |
eb28be2b AK |
741 | sdio->final_block_in_bio = sdio->cur_page_block + |
742 | (sdio->cur_page_len >> sdio->blkbits); | |
1da177e4 LT |
743 | ret = 0; |
744 | } else { | |
745 | ret = 1; | |
746 | } | |
747 | return ret; | |
748 | } | |
749 | ||
750 | /* | |
751 | * Put cur_page under IO. The section of cur_page which is described by | |
752 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page | |
753 | * starts on-disk at cur_page_block. | |
754 | * | |
755 | * We take a ref against the page here (on behalf of its presence in the bio). | |
756 | * | |
757 | * The caller of this function is responsible for removing cur_page from the | |
758 | * dio, and for dropping the refcount which came from that presence. | |
759 | */ | |
ba253fbf AK |
760 | static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio, |
761 | struct buffer_head *map_bh) | |
1da177e4 LT |
762 | { |
763 | int ret = 0; | |
764 | ||
eb28be2b AK |
765 | if (sdio->bio) { |
766 | loff_t cur_offset = sdio->cur_page_fs_offset; | |
767 | loff_t bio_next_offset = sdio->logical_offset_in_bio + | |
4f024f37 | 768 | sdio->bio->bi_iter.bi_size; |
c2c6ca41 | 769 | |
1da177e4 | 770 | /* |
c2c6ca41 JB |
771 | * See whether this new request is contiguous with the old. |
772 | * | |
f0940cee NK |
773 | * Btrfs cannot handle having logically non-contiguous requests |
774 | * submitted. For example if you have | |
c2c6ca41 JB |
775 | * |
776 | * Logical: [0-4095][HOLE][8192-12287] | |
f0940cee | 777 | * Physical: [0-4095] [4096-8191] |
c2c6ca41 JB |
778 | * |
779 | * We cannot submit those pages together as one BIO. So if our | |
780 | * current logical offset in the file does not equal what would | |
781 | * be the next logical offset in the bio, submit the bio we | |
782 | * have. | |
1da177e4 | 783 | */ |
eb28be2b | 784 | if (sdio->final_block_in_bio != sdio->cur_page_block || |
c2c6ca41 | 785 | cur_offset != bio_next_offset) |
eb28be2b | 786 | dio_bio_submit(dio, sdio); |
1da177e4 LT |
787 | } |
788 | ||
eb28be2b | 789 | if (sdio->bio == NULL) { |
18772641 | 790 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 LT |
791 | if (ret) |
792 | goto out; | |
793 | } | |
794 | ||
eb28be2b AK |
795 | if (dio_bio_add_page(sdio) != 0) { |
796 | dio_bio_submit(dio, sdio); | |
18772641 | 797 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 | 798 | if (ret == 0) { |
eb28be2b | 799 | ret = dio_bio_add_page(sdio); |
1da177e4 LT |
800 | BUG_ON(ret != 0); |
801 | } | |
802 | } | |
803 | out: | |
804 | return ret; | |
805 | } | |
806 | ||
807 | /* | |
808 | * An autonomous function to put a chunk of a page under deferred IO. | |
809 | * | |
810 | * The caller doesn't actually know (or care) whether this piece of page is in | |
811 | * a BIO, or is under IO or whatever. We just take care of all possible | |
812 | * situations here. The separation between the logic of do_direct_IO() and | |
813 | * that of submit_page_section() is important for clarity. Please don't break. | |
814 | * | |
815 | * The chunk of page starts on-disk at blocknr. | |
816 | * | |
817 | * We perform deferred IO, by recording the last-submitted page inside our | |
818 | * private part of the dio structure. If possible, we just expand the IO | |
819 | * across that page here. | |
820 | * | |
821 | * If that doesn't work out then we put the old page into the bio and add this | |
822 | * page to the dio instead. | |
823 | */ | |
ba253fbf | 824 | static inline int |
eb28be2b | 825 | submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, |
18772641 AK |
826 | unsigned offset, unsigned len, sector_t blocknr, |
827 | struct buffer_head *map_bh) | |
1da177e4 LT |
828 | { |
829 | int ret = 0; | |
830 | ||
8a4c1e42 | 831 | if (dio->op == REQ_OP_WRITE) { |
98c4d57d AM |
832 | /* |
833 | * Read accounting is performed in submit_bio() | |
834 | */ | |
835 | task_io_account_write(len); | |
836 | } | |
837 | ||
1da177e4 LT |
838 | /* |
839 | * Can we just grow the current page's presence in the dio? | |
840 | */ | |
eb28be2b AK |
841 | if (sdio->cur_page == page && |
842 | sdio->cur_page_offset + sdio->cur_page_len == offset && | |
843 | sdio->cur_page_block + | |
844 | (sdio->cur_page_len >> sdio->blkbits) == blocknr) { | |
845 | sdio->cur_page_len += len; | |
1da177e4 LT |
846 | goto out; |
847 | } | |
848 | ||
849 | /* | |
850 | * If there's a deferred page already there then send it. | |
851 | */ | |
eb28be2b | 852 | if (sdio->cur_page) { |
18772641 | 853 | ret = dio_send_cur_page(dio, sdio, map_bh); |
09cbfeaf | 854 | put_page(sdio->cur_page); |
eb28be2b | 855 | sdio->cur_page = NULL; |
1da177e4 | 856 | if (ret) |
b1058b98 | 857 | return ret; |
1da177e4 LT |
858 | } |
859 | ||
09cbfeaf | 860 | get_page(page); /* It is in dio */ |
eb28be2b AK |
861 | sdio->cur_page = page; |
862 | sdio->cur_page_offset = offset; | |
863 | sdio->cur_page_len = len; | |
864 | sdio->cur_page_block = blocknr; | |
865 | sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits; | |
1da177e4 | 866 | out: |
b1058b98 JK |
867 | /* |
868 | * If sdio->boundary then we want to schedule the IO now to | |
869 | * avoid metadata seeks. | |
870 | */ | |
871 | if (sdio->boundary) { | |
872 | ret = dio_send_cur_page(dio, sdio, map_bh); | |
899f0429 AG |
873 | if (sdio->bio) |
874 | dio_bio_submit(dio, sdio); | |
09cbfeaf | 875 | put_page(sdio->cur_page); |
b1058b98 JK |
876 | sdio->cur_page = NULL; |
877 | } | |
1da177e4 LT |
878 | return ret; |
879 | } | |
880 | ||
1da177e4 LT |
881 | /* |
882 | * If we are not writing the entire block and get_block() allocated | |
883 | * the block for us, we need to fill-in the unused portion of the | |
884 | * block with zeros. This happens only if user-buffer, fileoffset or | |
885 | * io length is not filesystem block-size multiple. | |
886 | * | |
887 | * `end' is zero if we're doing the start of the IO, 1 at the end of the | |
888 | * IO. | |
889 | */ | |
ba253fbf AK |
890 | static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio, |
891 | int end, struct buffer_head *map_bh) | |
1da177e4 LT |
892 | { |
893 | unsigned dio_blocks_per_fs_block; | |
894 | unsigned this_chunk_blocks; /* In dio_blocks */ | |
895 | unsigned this_chunk_bytes; | |
896 | struct page *page; | |
897 | ||
eb28be2b | 898 | sdio->start_zero_done = 1; |
18772641 | 899 | if (!sdio->blkfactor || !buffer_new(map_bh)) |
1da177e4 LT |
900 | return; |
901 | ||
eb28be2b AK |
902 | dio_blocks_per_fs_block = 1 << sdio->blkfactor; |
903 | this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1); | |
1da177e4 LT |
904 | |
905 | if (!this_chunk_blocks) | |
906 | return; | |
907 | ||
908 | /* | |
909 | * We need to zero out part of an fs block. It is either at the | |
910 | * beginning or the end of the fs block. | |
911 | */ | |
912 | if (end) | |
913 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; | |
914 | ||
eb28be2b | 915 | this_chunk_bytes = this_chunk_blocks << sdio->blkbits; |
1da177e4 | 916 | |
557ed1fa | 917 | page = ZERO_PAGE(0); |
eb28be2b | 918 | if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes, |
18772641 | 919 | sdio->next_block_for_io, map_bh)) |
1da177e4 LT |
920 | return; |
921 | ||
eb28be2b | 922 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 LT |
923 | } |
924 | ||
925 | /* | |
926 | * Walk the user pages, and the file, mapping blocks to disk and generating | |
927 | * a sequence of (page,offset,len,block) mappings. These mappings are injected | |
928 | * into submit_page_section(), which takes care of the next stage of submission | |
929 | * | |
930 | * Direct IO against a blockdev is different from a file. Because we can | |
931 | * happily perform page-sized but 512-byte aligned IOs. It is important that | |
932 | * blockdev IO be able to have fine alignment and large sizes. | |
933 | * | |
1d8fa7a2 | 934 | * So what we do is to permit the ->get_block function to populate bh.b_size |
1da177e4 LT |
935 | * with the size of IO which is permitted at this offset and this i_blkbits. |
936 | * | |
937 | * For best results, the blockdev should be set up with 512-byte i_blkbits and | |
1d8fa7a2 | 938 | * it should set b_size to PAGE_SIZE or more inside get_block(). This gives |
1da177e4 LT |
939 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
940 | */ | |
18772641 AK |
941 | static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, |
942 | struct buffer_head *map_bh) | |
1da177e4 | 943 | { |
eb28be2b | 944 | const unsigned blkbits = sdio->blkbits; |
dd545b52 | 945 | const unsigned i_blkbits = blkbits + sdio->blkfactor; |
1da177e4 LT |
946 | int ret = 0; |
947 | ||
eb28be2b | 948 | while (sdio->block_in_file < sdio->final_block_in_request) { |
7b2c99d1 AV |
949 | struct page *page; |
950 | size_t from, to; | |
6fcc5420 BH |
951 | |
952 | page = dio_get_page(dio, sdio); | |
1da177e4 LT |
953 | if (IS_ERR(page)) { |
954 | ret = PTR_ERR(page); | |
955 | goto out; | |
956 | } | |
6fcc5420 BH |
957 | from = sdio->head ? 0 : sdio->from; |
958 | to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE; | |
959 | sdio->head++; | |
1da177e4 | 960 | |
7b2c99d1 | 961 | while (from < to) { |
1da177e4 LT |
962 | unsigned this_chunk_bytes; /* # of bytes mapped */ |
963 | unsigned this_chunk_blocks; /* # of blocks */ | |
964 | unsigned u; | |
965 | ||
eb28be2b | 966 | if (sdio->blocks_available == 0) { |
1da177e4 LT |
967 | /* |
968 | * Need to go and map some more disk | |
969 | */ | |
970 | unsigned long blkmask; | |
971 | unsigned long dio_remainder; | |
972 | ||
18772641 | 973 | ret = get_more_blocks(dio, sdio, map_bh); |
1da177e4 | 974 | if (ret) { |
09cbfeaf | 975 | put_page(page); |
1da177e4 LT |
976 | goto out; |
977 | } | |
978 | if (!buffer_mapped(map_bh)) | |
979 | goto do_holes; | |
980 | ||
eb28be2b | 981 | sdio->blocks_available = |
f734c89c | 982 | map_bh->b_size >> blkbits; |
eb28be2b AK |
983 | sdio->next_block_for_io = |
984 | map_bh->b_blocknr << sdio->blkfactor; | |
f734c89c JK |
985 | if (buffer_new(map_bh)) { |
986 | clean_bdev_aliases( | |
987 | map_bh->b_bdev, | |
988 | map_bh->b_blocknr, | |
dd545b52 | 989 | map_bh->b_size >> i_blkbits); |
f734c89c | 990 | } |
1da177e4 | 991 | |
eb28be2b | 992 | if (!sdio->blkfactor) |
1da177e4 LT |
993 | goto do_holes; |
994 | ||
eb28be2b AK |
995 | blkmask = (1 << sdio->blkfactor) - 1; |
996 | dio_remainder = (sdio->block_in_file & blkmask); | |
1da177e4 LT |
997 | |
998 | /* | |
999 | * If we are at the start of IO and that IO | |
1000 | * starts partway into a fs-block, | |
1001 | * dio_remainder will be non-zero. If the IO | |
1002 | * is a read then we can simply advance the IO | |
1003 | * cursor to the first block which is to be | |
1004 | * read. But if the IO is a write and the | |
1005 | * block was newly allocated we cannot do that; | |
1006 | * the start of the fs block must be zeroed out | |
1007 | * on-disk | |
1008 | */ | |
1009 | if (!buffer_new(map_bh)) | |
eb28be2b AK |
1010 | sdio->next_block_for_io += dio_remainder; |
1011 | sdio->blocks_available -= dio_remainder; | |
1da177e4 LT |
1012 | } |
1013 | do_holes: | |
1014 | /* Handle holes */ | |
1015 | if (!buffer_mapped(map_bh)) { | |
35dc8161 | 1016 | loff_t i_size_aligned; |
1da177e4 LT |
1017 | |
1018 | /* AKPM: eargh, -ENOTBLK is a hack */ | |
8a4c1e42 | 1019 | if (dio->op == REQ_OP_WRITE) { |
09cbfeaf | 1020 | put_page(page); |
1da177e4 LT |
1021 | return -ENOTBLK; |
1022 | } | |
1023 | ||
35dc8161 JM |
1024 | /* |
1025 | * Be sure to account for a partial block as the | |
1026 | * last block in the file | |
1027 | */ | |
1028 | i_size_aligned = ALIGN(i_size_read(dio->inode), | |
1029 | 1 << blkbits); | |
eb28be2b | 1030 | if (sdio->block_in_file >= |
35dc8161 | 1031 | i_size_aligned >> blkbits) { |
1da177e4 | 1032 | /* We hit eof */ |
09cbfeaf | 1033 | put_page(page); |
1da177e4 LT |
1034 | goto out; |
1035 | } | |
7b2c99d1 | 1036 | zero_user(page, from, 1 << blkbits); |
eb28be2b | 1037 | sdio->block_in_file++; |
7b2c99d1 | 1038 | from += 1 << blkbits; |
3320c60b | 1039 | dio->result += 1 << blkbits; |
1da177e4 LT |
1040 | goto next_block; |
1041 | } | |
1042 | ||
1043 | /* | |
1044 | * If we're performing IO which has an alignment which | |
1045 | * is finer than the underlying fs, go check to see if | |
1046 | * we must zero out the start of this block. | |
1047 | */ | |
eb28be2b | 1048 | if (unlikely(sdio->blkfactor && !sdio->start_zero_done)) |
18772641 | 1049 | dio_zero_block(dio, sdio, 0, map_bh); |
1da177e4 LT |
1050 | |
1051 | /* | |
1052 | * Work out, in this_chunk_blocks, how much disk we | |
1053 | * can add to this page | |
1054 | */ | |
eb28be2b | 1055 | this_chunk_blocks = sdio->blocks_available; |
7b2c99d1 | 1056 | u = (to - from) >> blkbits; |
1da177e4 LT |
1057 | if (this_chunk_blocks > u) |
1058 | this_chunk_blocks = u; | |
eb28be2b | 1059 | u = sdio->final_block_in_request - sdio->block_in_file; |
1da177e4 LT |
1060 | if (this_chunk_blocks > u) |
1061 | this_chunk_blocks = u; | |
1062 | this_chunk_bytes = this_chunk_blocks << blkbits; | |
1063 | BUG_ON(this_chunk_bytes == 0); | |
1064 | ||
092c8d46 JK |
1065 | if (this_chunk_blocks == sdio->blocks_available) |
1066 | sdio->boundary = buffer_boundary(map_bh); | |
eb28be2b | 1067 | ret = submit_page_section(dio, sdio, page, |
7b2c99d1 | 1068 | from, |
eb28be2b | 1069 | this_chunk_bytes, |
18772641 AK |
1070 | sdio->next_block_for_io, |
1071 | map_bh); | |
1da177e4 | 1072 | if (ret) { |
09cbfeaf | 1073 | put_page(page); |
1da177e4 LT |
1074 | goto out; |
1075 | } | |
eb28be2b | 1076 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 | 1077 | |
eb28be2b | 1078 | sdio->block_in_file += this_chunk_blocks; |
7b2c99d1 AV |
1079 | from += this_chunk_bytes; |
1080 | dio->result += this_chunk_bytes; | |
eb28be2b | 1081 | sdio->blocks_available -= this_chunk_blocks; |
1da177e4 | 1082 | next_block: |
eb28be2b AK |
1083 | BUG_ON(sdio->block_in_file > sdio->final_block_in_request); |
1084 | if (sdio->block_in_file == sdio->final_block_in_request) | |
1da177e4 LT |
1085 | break; |
1086 | } | |
1087 | ||
1088 | /* Drop the ref which was taken in get_user_pages() */ | |
09cbfeaf | 1089 | put_page(page); |
1da177e4 LT |
1090 | } |
1091 | out: | |
1092 | return ret; | |
1093 | } | |
1094 | ||
847cc637 | 1095 | static inline int drop_refcount(struct dio *dio) |
1da177e4 | 1096 | { |
847cc637 | 1097 | int ret2; |
5eb6c7a2 | 1098 | unsigned long flags; |
1da177e4 | 1099 | |
8459d86a ZB |
1100 | /* |
1101 | * Sync will always be dropping the final ref and completing the | |
5eb6c7a2 ZB |
1102 | * operation. AIO can if it was a broken operation described above or |
1103 | * in fact if all the bios race to complete before we get here. In | |
1104 | * that case dio_complete() translates the EIOCBQUEUED into the proper | |
04b2fa9f | 1105 | * return code that the caller will hand to ->complete(). |
5eb6c7a2 ZB |
1106 | * |
1107 | * This is managed by the bio_lock instead of being an atomic_t so that | |
1108 | * completion paths can drop their ref and use the remaining count to | |
1109 | * decide to wake the submission path atomically. | |
8459d86a | 1110 | */ |
5eb6c7a2 ZB |
1111 | spin_lock_irqsave(&dio->bio_lock, flags); |
1112 | ret2 = --dio->refcount; | |
1113 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
847cc637 | 1114 | return ret2; |
1da177e4 LT |
1115 | } |
1116 | ||
eafdc7d1 CH |
1117 | /* |
1118 | * This is a library function for use by filesystem drivers. | |
1119 | * | |
1120 | * The locking rules are governed by the flags parameter: | |
1121 | * - if the flags value contains DIO_LOCKING we use a fancy locking | |
1122 | * scheme for dumb filesystems. | |
1123 | * For writes this function is called under i_mutex and returns with | |
1124 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | |
1125 | * taken and dropped again before returning. | |
eafdc7d1 CH |
1126 | * - if the flags value does NOT contain DIO_LOCKING we don't use any |
1127 | * internal locking but rather rely on the filesystem to synchronize | |
1128 | * direct I/O reads/writes versus each other and truncate. | |
df2d6f26 CH |
1129 | * |
1130 | * To help with locking against truncate we incremented the i_dio_count | |
1131 | * counter before starting direct I/O, and decrement it once we are done. | |
1132 | * Truncate can wait for it to reach zero to provide exclusion. It is | |
1133 | * expected that filesystem provide exclusion between new direct I/O | |
1134 | * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, | |
1135 | * but other filesystems need to take care of this on their own. | |
ba253fbf AK |
1136 | * |
1137 | * NOTE: if you pass "sdio" to anything by pointer make sure that function | |
1138 | * is always inlined. Otherwise gcc is unable to split the structure into | |
1139 | * individual fields and will generate much worse code. This is important | |
1140 | * for the whole file. | |
eafdc7d1 | 1141 | */ |
65dd2aa9 | 1142 | static inline ssize_t |
17f8c842 OS |
1143 | do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, |
1144 | struct block_device *bdev, struct iov_iter *iter, | |
c8b8e32d | 1145 | get_block_t get_block, dio_iodone_t end_io, |
17f8c842 | 1146 | dio_submit_t submit_io, int flags) |
1da177e4 | 1147 | { |
6aa7de05 | 1148 | unsigned i_blkbits = READ_ONCE(inode->i_blkbits); |
ab73857e | 1149 | unsigned blkbits = i_blkbits; |
1da177e4 LT |
1150 | unsigned blocksize_mask = (1 << blkbits) - 1; |
1151 | ssize_t retval = -EINVAL; | |
1c0ff0f1 | 1152 | const size_t count = iov_iter_count(iter); |
c8b8e32d | 1153 | loff_t offset = iocb->ki_pos; |
1c0ff0f1 | 1154 | const loff_t end = offset + count; |
1da177e4 | 1155 | struct dio *dio; |
eb28be2b | 1156 | struct dio_submit sdio = { 0, }; |
847cc637 | 1157 | struct buffer_head map_bh = { 0, }; |
647d1e4c | 1158 | struct blk_plug plug; |
886a3911 | 1159 | unsigned long align = offset | iov_iter_alignment(iter); |
1da177e4 | 1160 | |
65dd2aa9 AK |
1161 | /* |
1162 | * Avoid references to bdev if not absolutely needed to give | |
1163 | * the early prefetch in the caller enough time. | |
1164 | */ | |
1da177e4 | 1165 | |
886a3911 | 1166 | if (align & blocksize_mask) { |
1da177e4 | 1167 | if (bdev) |
65dd2aa9 | 1168 | blkbits = blksize_bits(bdev_logical_block_size(bdev)); |
1da177e4 | 1169 | blocksize_mask = (1 << blkbits) - 1; |
886a3911 | 1170 | if (align & blocksize_mask) |
1da177e4 LT |
1171 | goto out; |
1172 | } | |
1173 | ||
f9b5570d | 1174 | /* watch out for a 0 len io from a tricksy fs */ |
1c0ff0f1 | 1175 | if (iov_iter_rw(iter) == READ && !count) |
f9b5570d CH |
1176 | return 0; |
1177 | ||
6e8267f5 | 1178 | dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); |
1da177e4 LT |
1179 | retval = -ENOMEM; |
1180 | if (!dio) | |
1181 | goto out; | |
23aee091 JM |
1182 | /* |
1183 | * Believe it or not, zeroing out the page array caused a .5% | |
1184 | * performance regression in a database benchmark. So, we take | |
1185 | * care to only zero out what's needed. | |
1186 | */ | |
1187 | memset(dio, 0, offsetof(struct dio, pages)); | |
1da177e4 | 1188 | |
5fe878ae CH |
1189 | dio->flags = flags; |
1190 | if (dio->flags & DIO_LOCKING) { | |
17f8c842 | 1191 | if (iov_iter_rw(iter) == READ) { |
5fe878ae CH |
1192 | struct address_space *mapping = |
1193 | iocb->ki_filp->f_mapping; | |
1da177e4 | 1194 | |
5fe878ae | 1195 | /* will be released by direct_io_worker */ |
5955102c | 1196 | inode_lock(inode); |
1da177e4 LT |
1197 | |
1198 | retval = filemap_write_and_wait_range(mapping, offset, | |
1199 | end - 1); | |
1200 | if (retval) { | |
5955102c | 1201 | inode_unlock(inode); |
6e8267f5 | 1202 | kmem_cache_free(dio_cache, dio); |
1da177e4 LT |
1203 | goto out; |
1204 | } | |
1da177e4 | 1205 | } |
1da177e4 LT |
1206 | } |
1207 | ||
74cedf9b JK |
1208 | /* Once we sampled i_size check for reads beyond EOF */ |
1209 | dio->i_size = i_size_read(inode); | |
1210 | if (iov_iter_rw(iter) == READ && offset >= dio->i_size) { | |
1211 | if (dio->flags & DIO_LOCKING) | |
5955102c | 1212 | inode_unlock(inode); |
74cedf9b | 1213 | kmem_cache_free(dio_cache, dio); |
2d4594ac | 1214 | retval = 0; |
74cedf9b JK |
1215 | goto out; |
1216 | } | |
1217 | ||
1da177e4 | 1218 | /* |
60392573 CH |
1219 | * For file extending writes updating i_size before data writeouts |
1220 | * complete can expose uninitialized blocks in dumb filesystems. | |
1221 | * In that case we need to wait for I/O completion even if asked | |
1222 | * for an asynchronous write. | |
1da177e4 | 1223 | */ |
60392573 CH |
1224 | if (is_sync_kiocb(iocb)) |
1225 | dio->is_async = false; | |
c8f4c36f | 1226 | else if (iov_iter_rw(iter) == WRITE && end > i_size_read(inode)) |
60392573 CH |
1227 | dio->is_async = false; |
1228 | else | |
1229 | dio->is_async = true; | |
1230 | ||
847cc637 | 1231 | dio->inode = inode; |
8a4c1e42 MC |
1232 | if (iov_iter_rw(iter) == WRITE) { |
1233 | dio->op = REQ_OP_WRITE; | |
70fd7614 | 1234 | dio->op_flags = REQ_SYNC | REQ_IDLE; |
03a07c92 GR |
1235 | if (iocb->ki_flags & IOCB_NOWAIT) |
1236 | dio->op_flags |= REQ_NOWAIT; | |
8a4c1e42 MC |
1237 | } else { |
1238 | dio->op = REQ_OP_READ; | |
1239 | } | |
d1e36282 JA |
1240 | if (iocb->ki_flags & IOCB_HIPRI) |
1241 | dio->op_flags |= REQ_HIPRI; | |
02afc27f CH |
1242 | |
1243 | /* | |
1244 | * For AIO O_(D)SYNC writes we need to defer completions to a workqueue | |
1245 | * so that we can call ->fsync. | |
1246 | */ | |
332391a9 LC |
1247 | if (dio->is_async && iov_iter_rw(iter) == WRITE) { |
1248 | retval = 0; | |
d9c10e5b | 1249 | if (iocb->ki_flags & IOCB_DSYNC) |
332391a9 LC |
1250 | retval = dio_set_defer_completion(dio); |
1251 | else if (!dio->inode->i_sb->s_dio_done_wq) { | |
1252 | /* | |
1253 | * In case of AIO write racing with buffered read we | |
1254 | * need to defer completion. We can't decide this now, | |
1255 | * however the workqueue needs to be initialized here. | |
1256 | */ | |
1257 | retval = sb_init_dio_done_wq(dio->inode->i_sb); | |
1258 | } | |
02afc27f CH |
1259 | if (retval) { |
1260 | /* | |
1261 | * We grab i_mutex only for reads so we don't have | |
1262 | * to release it here | |
1263 | */ | |
1264 | kmem_cache_free(dio_cache, dio); | |
1265 | goto out; | |
1266 | } | |
1267 | } | |
1268 | ||
1269 | /* | |
1270 | * Will be decremented at I/O completion time. | |
1271 | */ | |
ce3077ee | 1272 | inode_dio_begin(inode); |
02afc27f CH |
1273 | |
1274 | retval = 0; | |
847cc637 | 1275 | sdio.blkbits = blkbits; |
ab73857e | 1276 | sdio.blkfactor = i_blkbits - blkbits; |
847cc637 AK |
1277 | sdio.block_in_file = offset >> blkbits; |
1278 | ||
1279 | sdio.get_block = get_block; | |
1280 | dio->end_io = end_io; | |
1281 | sdio.submit_io = submit_io; | |
1282 | sdio.final_block_in_bio = -1; | |
1283 | sdio.next_block_for_io = -1; | |
1284 | ||
1285 | dio->iocb = iocb; | |
847cc637 AK |
1286 | |
1287 | spin_lock_init(&dio->bio_lock); | |
1288 | dio->refcount = 1; | |
1289 | ||
00e23707 | 1290 | dio->should_dirty = iter_is_iovec(iter) && iov_iter_rw(iter) == READ; |
7b2c99d1 | 1291 | sdio.iter = iter; |
1c0ff0f1 | 1292 | sdio.final_block_in_request = end >> blkbits; |
7b2c99d1 | 1293 | |
847cc637 AK |
1294 | /* |
1295 | * In case of non-aligned buffers, we may need 2 more | |
1296 | * pages since we need to zero out first and last block. | |
1297 | */ | |
1298 | if (unlikely(sdio.blkfactor)) | |
1299 | sdio.pages_in_io = 2; | |
1300 | ||
f67da30c | 1301 | sdio.pages_in_io += iov_iter_npages(iter, INT_MAX); |
847cc637 | 1302 | |
647d1e4c FW |
1303 | blk_start_plug(&plug); |
1304 | ||
7b2c99d1 AV |
1305 | retval = do_direct_IO(dio, &sdio, &map_bh); |
1306 | if (retval) | |
1307 | dio_cleanup(dio, &sdio); | |
847cc637 AK |
1308 | |
1309 | if (retval == -ENOTBLK) { | |
1310 | /* | |
1311 | * The remaining part of the request will be | |
1312 | * be handled by buffered I/O when we return | |
1313 | */ | |
1314 | retval = 0; | |
1315 | } | |
1316 | /* | |
1317 | * There may be some unwritten disk at the end of a part-written | |
1318 | * fs-block-sized block. Go zero that now. | |
1319 | */ | |
1320 | dio_zero_block(dio, &sdio, 1, &map_bh); | |
1321 | ||
1322 | if (sdio.cur_page) { | |
1323 | ssize_t ret2; | |
1324 | ||
1325 | ret2 = dio_send_cur_page(dio, &sdio, &map_bh); | |
1326 | if (retval == 0) | |
1327 | retval = ret2; | |
09cbfeaf | 1328 | put_page(sdio.cur_page); |
847cc637 AK |
1329 | sdio.cur_page = NULL; |
1330 | } | |
1331 | if (sdio.bio) | |
1332 | dio_bio_submit(dio, &sdio); | |
1333 | ||
647d1e4c FW |
1334 | blk_finish_plug(&plug); |
1335 | ||
847cc637 AK |
1336 | /* |
1337 | * It is possible that, we return short IO due to end of file. | |
1338 | * In that case, we need to release all the pages we got hold on. | |
1339 | */ | |
1340 | dio_cleanup(dio, &sdio); | |
1341 | ||
1342 | /* | |
1343 | * All block lookups have been performed. For READ requests | |
1344 | * we can let i_mutex go now that its achieved its purpose | |
1345 | * of protecting us from looking up uninitialized blocks. | |
1346 | */ | |
17f8c842 | 1347 | if (iov_iter_rw(iter) == READ && (dio->flags & DIO_LOCKING)) |
5955102c | 1348 | inode_unlock(dio->inode); |
847cc637 AK |
1349 | |
1350 | /* | |
1351 | * The only time we want to leave bios in flight is when a successful | |
1352 | * partial aio read or full aio write have been setup. In that case | |
1353 | * bio completion will call aio_complete. The only time it's safe to | |
1354 | * call aio_complete is when we return -EIOCBQUEUED, so we key on that. | |
1355 | * This had *better* be the only place that raises -EIOCBQUEUED. | |
1356 | */ | |
1357 | BUG_ON(retval == -EIOCBQUEUED); | |
1358 | if (dio->is_async && retval == 0 && dio->result && | |
17f8c842 | 1359 | (iov_iter_rw(iter) == READ || dio->result == count)) |
847cc637 | 1360 | retval = -EIOCBQUEUED; |
af436472 | 1361 | else |
847cc637 AK |
1362 | dio_await_completion(dio); |
1363 | ||
1364 | if (drop_refcount(dio) == 0) { | |
ffe51f01 | 1365 | retval = dio_complete(dio, retval, DIO_COMPLETE_INVALIDATE); |
847cc637 AK |
1366 | } else |
1367 | BUG_ON(retval != -EIOCBQUEUED); | |
1da177e4 | 1368 | |
7bb46a67 | 1369 | out: |
1370 | return retval; | |
1371 | } | |
65dd2aa9 | 1372 | |
17f8c842 OS |
1373 | ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, |
1374 | struct block_device *bdev, struct iov_iter *iter, | |
c8b8e32d | 1375 | get_block_t get_block, |
17f8c842 OS |
1376 | dio_iodone_t end_io, dio_submit_t submit_io, |
1377 | int flags) | |
65dd2aa9 AK |
1378 | { |
1379 | /* | |
1380 | * The block device state is needed in the end to finally | |
1381 | * submit everything. Since it's likely to be cache cold | |
1382 | * prefetch it here as first thing to hide some of the | |
1383 | * latency. | |
1384 | * | |
1385 | * Attempt to prefetch the pieces we likely need later. | |
1386 | */ | |
1387 | prefetch(&bdev->bd_disk->part_tbl); | |
1388 | prefetch(bdev->bd_queue); | |
1389 | prefetch((char *)bdev->bd_queue + SMP_CACHE_BYTES); | |
1390 | ||
c8b8e32d | 1391 | return do_blockdev_direct_IO(iocb, inode, bdev, iter, get_block, |
17f8c842 | 1392 | end_io, submit_io, flags); |
65dd2aa9 AK |
1393 | } |
1394 | ||
1da177e4 | 1395 | EXPORT_SYMBOL(__blockdev_direct_IO); |
6e8267f5 AK |
1396 | |
1397 | static __init int dio_init(void) | |
1398 | { | |
1399 | dio_cache = KMEM_CACHE(dio, SLAB_PANIC); | |
1400 | return 0; | |
1401 | } | |
1402 | module_init(dio_init) |