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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 | 41 | |
b16155a0 EB |
42 | #include "internal.h" |
43 | ||
1da177e4 | 44 | /* |
1ccf164e DH |
45 | * How many user pages to map in one call to iov_iter_extract_pages(). This |
46 | * determines the size of a structure in the slab cache | |
1da177e4 LT |
47 | */ |
48 | #define DIO_PAGES 64 | |
49 | ||
ffe51f01 LC |
50 | /* |
51 | * Flags for dio_complete() | |
52 | */ | |
53 | #define DIO_COMPLETE_ASYNC 0x01 /* This is async IO */ | |
54 | #define DIO_COMPLETE_INVALIDATE 0x02 /* Can invalidate pages */ | |
55 | ||
1da177e4 LT |
56 | /* |
57 | * This code generally works in units of "dio_blocks". A dio_block is | |
58 | * somewhere between the hard sector size and the filesystem block size. it | |
59 | * is determined on a per-invocation basis. When talking to the filesystem | |
60 | * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity | |
61 | * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted | |
62 | * to bio_block quantities by shifting left by blkfactor. | |
63 | * | |
64 | * If blkfactor is zero then the user's request was aligned to the filesystem's | |
65 | * blocksize. | |
1da177e4 LT |
66 | */ |
67 | ||
eb28be2b AK |
68 | /* dio_state only used in the submission path */ |
69 | ||
70 | struct dio_submit { | |
1da177e4 | 71 | struct bio *bio; /* bio under assembly */ |
1da177e4 LT |
72 | unsigned blkbits; /* doesn't change */ |
73 | unsigned blkfactor; /* When we're using an alignment which | |
74 | is finer than the filesystem's soft | |
75 | blocksize, this specifies how much | |
76 | finer. blkfactor=2 means 1/4-block | |
77 | alignment. Does not change */ | |
78 | unsigned start_zero_done; /* flag: sub-blocksize zeroing has | |
79 | been performed at the start of a | |
80 | write */ | |
81 | int pages_in_io; /* approximate total IO pages */ | |
1da177e4 LT |
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 */ | |
0dc2bc49 | 85 | int reap_counter; /* rate limit reaping */ |
1da177e4 | 86 | sector_t final_block_in_request;/* doesn't change */ |
1da177e4 | 87 | int boundary; /* prev block is at a boundary */ |
1d8fa7a2 | 88 | get_block_t *get_block; /* block mapping function */ |
eb28be2b | 89 | |
facd07b0 | 90 | loff_t logical_offset_in_bio; /* current first logical block in bio */ |
1da177e4 LT |
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 */ | |
1da177e4 LT |
94 | |
95 | /* | |
96 | * Deferred addition of a page to the dio. These variables are | |
97 | * private to dio_send_cur_page(), submit_page_section() and | |
98 | * dio_bio_add_page(). | |
99 | */ | |
100 | struct page *cur_page; /* The page */ | |
101 | unsigned cur_page_offset; /* Offset into it, in bytes */ | |
102 | unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ | |
103 | sector_t cur_page_block; /* Where it starts */ | |
facd07b0 | 104 | loff_t cur_page_fs_offset; /* Offset in file */ |
1da177e4 | 105 | |
7b2c99d1 | 106 | struct iov_iter *iter; |
1da177e4 LT |
107 | /* |
108 | * Page queue. These variables belong to dio_refill_pages() and | |
109 | * dio_get_page(). | |
110 | */ | |
1da177e4 LT |
111 | unsigned head; /* next page to process */ |
112 | unsigned tail; /* last valid page + 1 */ | |
7b2c99d1 | 113 | size_t from, to; |
eb28be2b AK |
114 | }; |
115 | ||
116 | /* dio_state communicated between submission path and end_io */ | |
117 | struct dio { | |
118 | int flags; /* doesn't change */ | |
c6293eac | 119 | blk_opf_t opf; /* request operation type and flags */ |
74d46992 | 120 | struct gendisk *bio_disk; |
0dc2bc49 | 121 | struct inode *inode; |
eb28be2b AK |
122 | loff_t i_size; /* i_size when submitted */ |
123 | dio_iodone_t *end_io; /* IO completion function */ | |
1ccf164e | 124 | bool is_pinned; /* T if we have pins on the pages */ |
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 */ | |
1ccf164e | 130 | int page_errors; /* err from iov_iter_extract_pages() */ |
0dc2bc49 | 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 | { |
1ccf164e | 169 | struct page **pages = dio->pages; |
c6293eac | 170 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
7b2c99d1 | 171 | ssize_t ret; |
1da177e4 | 172 | |
1ccf164e DH |
173 | ret = iov_iter_extract_pages(sdio->iter, &pages, LONG_MAX, |
174 | DIO_PAGES, 0, &sdio->from); | |
1da177e4 | 175 | |
c6293eac | 176 | if (ret < 0 && sdio->blocks_available && dio_op == REQ_OP_WRITE) { |
1da177e4 LT |
177 | /* |
178 | * A memory fault, but the filesystem has some outstanding | |
179 | * mapped blocks. We need to use those blocks up to avoid | |
180 | * leaking stale data in the file. | |
181 | */ | |
182 | if (dio->page_errors == 0) | |
183 | dio->page_errors = ret; | |
1ccf164e | 184 | dio->pages[0] = ZERO_PAGE(0); |
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 | 193 | ret += sdio->from; |
eb28be2b | 194 | sdio->head = 0; |
7b2c99d1 AV |
195 | sdio->tail = (ret + PAGE_SIZE - 1) / PAGE_SIZE; |
196 | sdio->to = ((ret - 1) & (PAGE_SIZE - 1)) + 1; | |
197 | return 0; | |
1da177e4 | 198 | } |
1da177e4 LT |
199 | return ret; |
200 | } | |
201 | ||
202 | /* | |
203 | * Get another userspace page. Returns an ERR_PTR on error. Pages are | |
1ccf164e DH |
204 | * buffered inside the dio so that we can call iov_iter_extract_pages() |
205 | * against a decent number of pages, less frequently. To provide nicer use of | |
206 | * the L1 cache. | |
1da177e4 | 207 | */ |
ba253fbf | 208 | static inline struct page *dio_get_page(struct dio *dio, |
6fcc5420 | 209 | struct dio_submit *sdio) |
1da177e4 | 210 | { |
eb28be2b | 211 | if (dio_pages_present(sdio) == 0) { |
1da177e4 LT |
212 | int ret; |
213 | ||
eb28be2b | 214 | ret = dio_refill_pages(dio, sdio); |
1da177e4 LT |
215 | if (ret) |
216 | return ERR_PTR(ret); | |
eb28be2b | 217 | BUG_ON(dio_pages_present(sdio) == 0); |
1da177e4 | 218 | } |
6fcc5420 | 219 | return dio->pages[sdio->head]; |
1da177e4 LT |
220 | } |
221 | ||
1ccf164e DH |
222 | static void dio_pin_page(struct dio *dio, struct page *page) |
223 | { | |
224 | if (dio->is_pinned) | |
225 | folio_add_pin(page_folio(page)); | |
226 | } | |
227 | ||
228 | static void dio_unpin_page(struct dio *dio, struct page *page) | |
229 | { | |
230 | if (dio->is_pinned) | |
231 | unpin_user_page(page); | |
232 | } | |
233 | ||
c70d868f | 234 | /* |
6d544bb4 | 235 | * dio_complete() - called when all DIO BIO I/O has been completed |
6d544bb4 | 236 | * |
7b7a8665 CH |
237 | * This drops i_dio_count, lets interested parties know that a DIO operation |
238 | * has completed, and calculates the resulting return code for the operation. | |
6d544bb4 ZB |
239 | * |
240 | * It lets the filesystem know if it registered an interest earlier via | |
241 | * get_block. Pass the private field of the map buffer_head so that | |
242 | * filesystems can use it to hold additional state between get_block calls and | |
243 | * dio_complete. | |
1da177e4 | 244 | */ |
ffe51f01 | 245 | static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags) |
1da177e4 | 246 | { |
c6293eac | 247 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
716b9bc0 | 248 | loff_t offset = dio->iocb->ki_pos; |
6d544bb4 | 249 | ssize_t transferred = 0; |
332391a9 | 250 | int err; |
6d544bb4 | 251 | |
8459d86a ZB |
252 | /* |
253 | * AIO submission can race with bio completion to get here while | |
254 | * expecting to have the last io completed by bio completion. | |
255 | * In that case -EIOCBQUEUED is in fact not an error we want | |
256 | * to preserve through this call. | |
257 | */ | |
258 | if (ret == -EIOCBQUEUED) | |
259 | ret = 0; | |
260 | ||
6d544bb4 ZB |
261 | if (dio->result) { |
262 | transferred = dio->result; | |
263 | ||
264 | /* Check for short read case */ | |
c6293eac | 265 | if (dio_op == REQ_OP_READ && |
8a4c1e42 | 266 | ((offset + transferred) > dio->i_size)) |
6d544bb4 | 267 | transferred = dio->i_size - offset; |
4038acdb AV |
268 | /* ignore EFAULT if some IO has been done */ |
269 | if (unlikely(ret == -EFAULT) && transferred) | |
270 | ret = 0; | |
6d544bb4 ZB |
271 | } |
272 | ||
6d544bb4 ZB |
273 | if (ret == 0) |
274 | ret = dio->page_errors; | |
275 | if (ret == 0) | |
276 | ret = dio->io_error; | |
277 | if (ret == 0) | |
278 | ret = transferred; | |
279 | ||
5e25c269 EG |
280 | if (dio->end_io) { |
281 | // XXX: ki_pos?? | |
282 | err = dio->end_io(dio->iocb, offset, ret, dio->private); | |
283 | if (err) | |
284 | ret = err; | |
285 | } | |
286 | ||
332391a9 LC |
287 | /* |
288 | * Try again to invalidate clean pages which might have been cached by | |
289 | * non-direct readahead, or faulted in by get_user_pages() if the source | |
290 | * of the write was an mmap'ed region of the file we're writing. Either | |
291 | * one is a pretty crazy thing to do, so we don't support it 100%. If | |
292 | * this invalidation fails, tough, the write still worked... | |
5e25c269 EG |
293 | * |
294 | * And this page cache invalidation has to be after dio->end_io(), as | |
295 | * some filesystems convert unwritten extents to real allocations in | |
296 | * end_io() when necessary, otherwise a racing buffer read would cache | |
297 | * zeros from unwritten extents. | |
332391a9 | 298 | */ |
ffe51f01 | 299 | if (flags & DIO_COMPLETE_INVALIDATE && |
c402a9a9 CH |
300 | ret > 0 && dio_op == REQ_OP_WRITE) |
301 | kiocb_invalidate_post_direct_write(dio->iocb, ret); | |
332391a9 | 302 | |
ce3077ee | 303 | inode_dio_end(dio->inode); |
fe0f07d0 | 304 | |
ffe51f01 | 305 | if (flags & DIO_COMPLETE_ASYNC) { |
e2592217 CH |
306 | /* |
307 | * generic_write_sync expects ki_pos to have been updated | |
308 | * already, but the submission path only does this for | |
309 | * synchronous I/O. | |
310 | */ | |
311 | dio->iocb->ki_pos += transferred; | |
02afc27f | 312 | |
c6293eac | 313 | if (ret > 0 && dio_op == REQ_OP_WRITE) |
41e817bc | 314 | ret = generic_write_sync(dio->iocb, ret); |
6b19b766 | 315 | dio->iocb->ki_complete(dio->iocb, ret); |
02afc27f | 316 | } |
40e2e973 | 317 | |
7b7a8665 | 318 | kmem_cache_free(dio_cache, dio); |
6d544bb4 | 319 | return ret; |
1da177e4 LT |
320 | } |
321 | ||
7b7a8665 CH |
322 | static void dio_aio_complete_work(struct work_struct *work) |
323 | { | |
324 | struct dio *dio = container_of(work, struct dio, complete_work); | |
325 | ||
ffe51f01 | 326 | dio_complete(dio, 0, DIO_COMPLETE_ASYNC | DIO_COMPLETE_INVALIDATE); |
7b7a8665 CH |
327 | } |
328 | ||
4e4cbee9 | 329 | static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio); |
7b7a8665 | 330 | |
1da177e4 LT |
331 | /* |
332 | * Asynchronous IO callback. | |
333 | */ | |
4246a0b6 | 334 | static void dio_bio_end_aio(struct bio *bio) |
1da177e4 LT |
335 | { |
336 | struct dio *dio = bio->bi_private; | |
c6293eac | 337 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
5eb6c7a2 ZB |
338 | unsigned long remaining; |
339 | unsigned long flags; | |
332391a9 | 340 | bool defer_completion = false; |
1da177e4 | 341 | |
1da177e4 LT |
342 | /* cleanup the bio */ |
343 | dio_bio_complete(dio, bio); | |
0273201e | 344 | |
5eb6c7a2 ZB |
345 | spin_lock_irqsave(&dio->bio_lock, flags); |
346 | remaining = --dio->refcount; | |
347 | if (remaining == 1 && dio->waiter) | |
20258b2b | 348 | wake_up_process(dio->waiter); |
5eb6c7a2 | 349 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
20258b2b | 350 | |
8459d86a | 351 | if (remaining == 0) { |
332391a9 LC |
352 | /* |
353 | * Defer completion when defer_completion is set or | |
354 | * when the inode has pages mapped and this is AIO write. | |
355 | * We need to invalidate those pages because there is a | |
356 | * chance they contain stale data in the case buffered IO | |
357 | * went in between AIO submission and completion into the | |
358 | * same region. | |
359 | */ | |
360 | if (dio->result) | |
361 | defer_completion = dio->defer_completion || | |
c6293eac | 362 | (dio_op == REQ_OP_WRITE && |
332391a9 LC |
363 | dio->inode->i_mapping->nrpages); |
364 | if (defer_completion) { | |
7b7a8665 CH |
365 | INIT_WORK(&dio->complete_work, dio_aio_complete_work); |
366 | queue_work(dio->inode->i_sb->s_dio_done_wq, | |
367 | &dio->complete_work); | |
368 | } else { | |
ffe51f01 | 369 | dio_complete(dio, 0, DIO_COMPLETE_ASYNC); |
7b7a8665 | 370 | } |
8459d86a | 371 | } |
1da177e4 LT |
372 | } |
373 | ||
374 | /* | |
375 | * The BIO completion handler simply queues the BIO up for the process-context | |
376 | * handler. | |
377 | * | |
378 | * During I/O bi_private points at the dio. After I/O, bi_private is used to | |
379 | * implement a singly-linked list of completed BIOs, at dio->bio_list. | |
380 | */ | |
4246a0b6 | 381 | static void dio_bio_end_io(struct bio *bio) |
1da177e4 LT |
382 | { |
383 | struct dio *dio = bio->bi_private; | |
384 | unsigned long flags; | |
385 | ||
1da177e4 LT |
386 | spin_lock_irqsave(&dio->bio_lock, flags); |
387 | bio->bi_private = dio->bio_list; | |
388 | dio->bio_list = bio; | |
5eb6c7a2 | 389 | if (--dio->refcount == 1 && dio->waiter) |
1da177e4 LT |
390 | wake_up_process(dio->waiter); |
391 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
1da177e4 LT |
392 | } |
393 | ||
ba253fbf | 394 | static inline void |
eb28be2b AK |
395 | dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, |
396 | struct block_device *bdev, | |
397 | sector_t first_sector, int nr_vecs) | |
1da177e4 LT |
398 | { |
399 | struct bio *bio; | |
400 | ||
20d9600c | 401 | /* |
0eb0b63c CH |
402 | * bio_alloc() is guaranteed to return a bio when allowed to sleep and |
403 | * we request a valid number of vectors. | |
20d9600c | 404 | */ |
c6293eac | 405 | bio = bio_alloc(bdev, nr_vecs, dio->opf, GFP_KERNEL); |
4f024f37 | 406 | bio->bi_iter.bi_sector = first_sector; |
1da177e4 LT |
407 | if (dio->is_async) |
408 | bio->bi_end_io = dio_bio_end_aio; | |
409 | else | |
410 | bio->bi_end_io = dio_bio_end_io; | |
1ccf164e DH |
411 | if (dio->is_pinned) |
412 | bio_set_flag(bio, BIO_PAGE_PINNED); | |
eb28be2b AK |
413 | sdio->bio = bio; |
414 | sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; | |
1da177e4 LT |
415 | } |
416 | ||
417 | /* | |
418 | * In the AIO read case we speculatively dirty the pages before starting IO. | |
419 | * During IO completion, any of these pages which happen to have been written | |
420 | * back will be redirtied by bio_check_pages_dirty(). | |
0273201e ZB |
421 | * |
422 | * bios hold a dio reference between submit_bio and ->end_io. | |
1da177e4 | 423 | */ |
ba253fbf | 424 | static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 425 | { |
c6293eac | 426 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
eb28be2b | 427 | struct bio *bio = sdio->bio; |
5eb6c7a2 | 428 | unsigned long flags; |
1da177e4 LT |
429 | |
430 | bio->bi_private = dio; | |
5eb6c7a2 ZB |
431 | |
432 | spin_lock_irqsave(&dio->bio_lock, flags); | |
433 | dio->refcount++; | |
434 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
435 | ||
c6293eac | 436 | if (dio->is_async && dio_op == REQ_OP_READ && dio->should_dirty) |
1da177e4 | 437 | bio_set_pages_dirty(bio); |
5eb6c7a2 | 438 | |
309dca30 | 439 | dio->bio_disk = bio->bi_bdev->bd_disk; |
c1c53460 | 440 | |
0aaf08de | 441 | submit_bio(bio); |
1da177e4 | 442 | |
eb28be2b AK |
443 | sdio->bio = NULL; |
444 | sdio->boundary = 0; | |
445 | sdio->logical_offset_in_bio = 0; | |
1da177e4 LT |
446 | } |
447 | ||
448 | /* | |
449 | * Release any resources in case of a failure | |
450 | */ | |
ba253fbf | 451 | static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 452 | { |
1ccf164e DH |
453 | if (dio->is_pinned) |
454 | unpin_user_pages(dio->pages + sdio->head, | |
455 | sdio->tail - sdio->head); | |
d44c4042 | 456 | sdio->head = sdio->tail; |
1da177e4 LT |
457 | } |
458 | ||
459 | /* | |
0273201e ZB |
460 | * Wait for the next BIO to complete. Remove it and return it. NULL is |
461 | * returned once all BIOs have been completed. This must only be called once | |
462 | * all bios have been issued so that dio->refcount can only decrease. This | |
3d742d4b | 463 | * requires that the caller hold a reference on the dio. |
1da177e4 LT |
464 | */ |
465 | static struct bio *dio_await_one(struct dio *dio) | |
466 | { | |
467 | unsigned long flags; | |
0273201e | 468 | struct bio *bio = NULL; |
1da177e4 LT |
469 | |
470 | spin_lock_irqsave(&dio->bio_lock, flags); | |
5eb6c7a2 ZB |
471 | |
472 | /* | |
473 | * Wait as long as the list is empty and there are bios in flight. bio | |
474 | * completion drops the count, maybe adds to the list, and wakes while | |
475 | * holding the bio_lock so we don't need set_current_state()'s barrier | |
476 | * and can call it after testing our condition. | |
477 | */ | |
478 | while (dio->refcount > 1 && dio->bio_list == NULL) { | |
479 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
480 | dio->waiter = current; | |
481 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
94c2ed58 | 482 | blk_io_schedule(); |
5eb6c7a2 ZB |
483 | /* wake up sets us TASK_RUNNING */ |
484 | spin_lock_irqsave(&dio->bio_lock, flags); | |
485 | dio->waiter = NULL; | |
1da177e4 | 486 | } |
0273201e ZB |
487 | if (dio->bio_list) { |
488 | bio = dio->bio_list; | |
489 | dio->bio_list = bio->bi_private; | |
490 | } | |
1da177e4 LT |
491 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
492 | return bio; | |
493 | } | |
494 | ||
495 | /* | |
496 | * Process one completed BIO. No locks are held. | |
497 | */ | |
4e4cbee9 | 498 | static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio) |
1da177e4 | 499 | { |
4e4cbee9 | 500 | blk_status_t err = bio->bi_status; |
c6293eac BVA |
501 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
502 | bool should_dirty = dio_op == REQ_OP_READ && dio->should_dirty; | |
1da177e4 | 503 | |
03a07c92 GR |
504 | if (err) { |
505 | if (err == BLK_STS_AGAIN && (bio->bi_opf & REQ_NOWAIT)) | |
506 | dio->io_error = -EAGAIN; | |
507 | else | |
508 | dio->io_error = -EIO; | |
509 | } | |
1da177e4 | 510 | |
d7c8aa85 | 511 | if (dio->is_async && should_dirty) { |
7ddc971f | 512 | bio_check_pages_dirty(bio); /* transfers ownership */ |
1da177e4 | 513 | } else { |
d7c8aa85 | 514 | bio_release_pages(bio, should_dirty); |
1da177e4 LT |
515 | bio_put(bio); |
516 | } | |
9b81c842 | 517 | return err; |
1da177e4 LT |
518 | } |
519 | ||
520 | /* | |
0273201e ZB |
521 | * Wait on and process all in-flight BIOs. This must only be called once |
522 | * all bios have been issued so that the refcount can only decrease. | |
523 | * This just waits for all bios to make it through dio_bio_complete. IO | |
beb7dd86 | 524 | * errors are propagated through dio->io_error and should be propagated via |
0273201e | 525 | * dio_complete(). |
1da177e4 | 526 | */ |
6d544bb4 | 527 | static void dio_await_completion(struct dio *dio) |
1da177e4 | 528 | { |
0273201e ZB |
529 | struct bio *bio; |
530 | do { | |
531 | bio = dio_await_one(dio); | |
532 | if (bio) | |
533 | dio_bio_complete(dio, bio); | |
534 | } while (bio); | |
1da177e4 LT |
535 | } |
536 | ||
537 | /* | |
538 | * A really large O_DIRECT read or write can generate a lot of BIOs. So | |
539 | * to keep the memory consumption sane we periodically reap any completed BIOs | |
540 | * during the BIO generation phase. | |
541 | * | |
542 | * This also helps to limit the peak amount of pinned userspace memory. | |
543 | */ | |
ba253fbf | 544 | static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
545 | { |
546 | int ret = 0; | |
547 | ||
eb28be2b | 548 | if (sdio->reap_counter++ >= 64) { |
1da177e4 LT |
549 | while (dio->bio_list) { |
550 | unsigned long flags; | |
551 | struct bio *bio; | |
552 | int ret2; | |
553 | ||
554 | spin_lock_irqsave(&dio->bio_lock, flags); | |
555 | bio = dio->bio_list; | |
556 | dio->bio_list = bio->bi_private; | |
557 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
4e4cbee9 | 558 | ret2 = blk_status_to_errno(dio_bio_complete(dio, bio)); |
1da177e4 LT |
559 | if (ret == 0) |
560 | ret = ret2; | |
561 | } | |
eb28be2b | 562 | sdio->reap_counter = 0; |
1da177e4 LT |
563 | } |
564 | return ret; | |
565 | } | |
566 | ||
7b7a8665 CH |
567 | static int dio_set_defer_completion(struct dio *dio) |
568 | { | |
569 | struct super_block *sb = dio->inode->i_sb; | |
570 | ||
571 | if (dio->defer_completion) | |
572 | return 0; | |
573 | dio->defer_completion = true; | |
574 | if (!sb->s_dio_done_wq) | |
575 | return sb_init_dio_done_wq(sb); | |
576 | return 0; | |
577 | } | |
578 | ||
1da177e4 LT |
579 | /* |
580 | * Call into the fs to map some more disk blocks. We record the current number | |
eb28be2b | 581 | * of available blocks at sdio->blocks_available. These are in units of the |
93407472 | 582 | * fs blocksize, i_blocksize(inode). |
1da177e4 LT |
583 | * |
584 | * The fs is allowed to map lots of blocks at once. If it wants to do that, | |
585 | * it uses the passed inode-relative block number as the file offset, as usual. | |
586 | * | |
1d8fa7a2 | 587 | * get_block() is passed the number of i_blkbits-sized blocks which direct_io |
1da177e4 LT |
588 | * has remaining to do. The fs should not map more than this number of blocks. |
589 | * | |
590 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to | |
591 | * indicate how much contiguous disk space has been made available at | |
592 | * bh->b_blocknr. | |
593 | * | |
594 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). | |
595 | * This isn't very efficient... | |
596 | * | |
597 | * In the case of filesystem holes: the fs may return an arbitrarily-large | |
598 | * hole by returning an appropriate value in b_size and by clearing | |
599 | * buffer_mapped(). However the direct-io code will only process holes one | |
1d8fa7a2 | 600 | * block at a time - it will repeatedly call get_block() as it walks the hole. |
1da177e4 | 601 | */ |
18772641 AK |
602 | static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, |
603 | struct buffer_head *map_bh) | |
1da177e4 | 604 | { |
c6293eac | 605 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
1da177e4 | 606 | int ret; |
1da177e4 | 607 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ |
ae55e1aa | 608 | sector_t fs_endblk; /* Into file, in filesystem-sized blocks */ |
1da177e4 | 609 | unsigned long fs_count; /* Number of filesystem-sized blocks */ |
1da177e4 | 610 | int create; |
ab73857e | 611 | unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor; |
8b9433eb | 612 | loff_t i_size; |
1da177e4 LT |
613 | |
614 | /* | |
615 | * If there was a memory error and we've overwritten all the | |
616 | * mapped blocks then we can now return that memory error | |
617 | */ | |
618 | ret = dio->page_errors; | |
619 | if (ret == 0) { | |
eb28be2b AK |
620 | BUG_ON(sdio->block_in_file >= sdio->final_block_in_request); |
621 | fs_startblk = sdio->block_in_file >> sdio->blkfactor; | |
ae55e1aa TM |
622 | fs_endblk = (sdio->final_block_in_request - 1) >> |
623 | sdio->blkfactor; | |
624 | fs_count = fs_endblk - fs_startblk + 1; | |
1da177e4 | 625 | |
3c674e74 | 626 | map_bh->b_state = 0; |
ab73857e | 627 | map_bh->b_size = fs_count << i_blkbits; |
3c674e74 | 628 | |
5fe878ae | 629 | /* |
9ecd10b7 EG |
630 | * For writes that could fill holes inside i_size on a |
631 | * DIO_SKIP_HOLES filesystem we forbid block creations: only | |
632 | * overwrites are permitted. We will return early to the caller | |
633 | * once we see an unmapped buffer head returned, and the caller | |
634 | * will fall back to buffered I/O. | |
5fe878ae CH |
635 | * |
636 | * Otherwise the decision is left to the get_blocks method, | |
637 | * which may decide to handle it or also return an unmapped | |
638 | * buffer head. | |
639 | */ | |
c6293eac | 640 | create = dio_op == REQ_OP_WRITE; |
5fe878ae | 641 | if (dio->flags & DIO_SKIP_HOLES) { |
8b9433eb EF |
642 | i_size = i_size_read(dio->inode); |
643 | if (i_size && fs_startblk <= (i_size - 1) >> i_blkbits) | |
1da177e4 | 644 | create = 0; |
1da177e4 | 645 | } |
3c674e74 | 646 | |
eb28be2b | 647 | ret = (*sdio->get_block)(dio->inode, fs_startblk, |
1da177e4 | 648 | map_bh, create); |
18772641 AK |
649 | |
650 | /* Store for completion */ | |
651 | dio->private = map_bh->b_private; | |
7b7a8665 CH |
652 | |
653 | if (ret == 0 && buffer_defer_completion(map_bh)) | |
654 | ret = dio_set_defer_completion(dio); | |
1da177e4 LT |
655 | } |
656 | return ret; | |
657 | } | |
658 | ||
659 | /* | |
660 | * There is no bio. Make one now. | |
661 | */ | |
ba253fbf AK |
662 | static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio, |
663 | sector_t start_sector, struct buffer_head *map_bh) | |
1da177e4 LT |
664 | { |
665 | sector_t sector; | |
666 | int ret, nr_pages; | |
667 | ||
eb28be2b | 668 | ret = dio_bio_reap(dio, sdio); |
1da177e4 LT |
669 | if (ret) |
670 | goto out; | |
eb28be2b | 671 | sector = start_sector << (sdio->blkbits - 9); |
5f7136db | 672 | nr_pages = bio_max_segs(sdio->pages_in_io); |
1da177e4 | 673 | BUG_ON(nr_pages <= 0); |
18772641 | 674 | dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages); |
eb28be2b | 675 | sdio->boundary = 0; |
1da177e4 LT |
676 | out: |
677 | return ret; | |
678 | } | |
679 | ||
680 | /* | |
681 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If | |
682 | * that was successful then update final_block_in_bio and take a ref against | |
683 | * the just-added page. | |
684 | * | |
685 | * Return zero on success. Non-zero means the caller needs to start a new BIO. | |
686 | */ | |
1ccf164e | 687 | static inline int dio_bio_add_page(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
688 | { |
689 | int ret; | |
690 | ||
eb28be2b AK |
691 | ret = bio_add_page(sdio->bio, sdio->cur_page, |
692 | sdio->cur_page_len, sdio->cur_page_offset); | |
693 | if (ret == sdio->cur_page_len) { | |
1da177e4 LT |
694 | /* |
695 | * Decrement count only, if we are done with this page | |
696 | */ | |
eb28be2b AK |
697 | if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE) |
698 | sdio->pages_in_io--; | |
1ccf164e | 699 | dio_pin_page(dio, sdio->cur_page); |
eb28be2b AK |
700 | sdio->final_block_in_bio = sdio->cur_page_block + |
701 | (sdio->cur_page_len >> sdio->blkbits); | |
1da177e4 LT |
702 | ret = 0; |
703 | } else { | |
704 | ret = 1; | |
705 | } | |
706 | return ret; | |
707 | } | |
708 | ||
709 | /* | |
710 | * Put cur_page under IO. The section of cur_page which is described by | |
711 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page | |
712 | * starts on-disk at cur_page_block. | |
713 | * | |
714 | * We take a ref against the page here (on behalf of its presence in the bio). | |
715 | * | |
716 | * The caller of this function is responsible for removing cur_page from the | |
717 | * dio, and for dropping the refcount which came from that presence. | |
718 | */ | |
ba253fbf AK |
719 | static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio, |
720 | struct buffer_head *map_bh) | |
1da177e4 LT |
721 | { |
722 | int ret = 0; | |
723 | ||
eb28be2b AK |
724 | if (sdio->bio) { |
725 | loff_t cur_offset = sdio->cur_page_fs_offset; | |
726 | loff_t bio_next_offset = sdio->logical_offset_in_bio + | |
4f024f37 | 727 | sdio->bio->bi_iter.bi_size; |
c2c6ca41 | 728 | |
1da177e4 | 729 | /* |
c2c6ca41 JB |
730 | * See whether this new request is contiguous with the old. |
731 | * | |
f0940cee NK |
732 | * Btrfs cannot handle having logically non-contiguous requests |
733 | * submitted. For example if you have | |
c2c6ca41 JB |
734 | * |
735 | * Logical: [0-4095][HOLE][8192-12287] | |
f0940cee | 736 | * Physical: [0-4095] [4096-8191] |
c2c6ca41 JB |
737 | * |
738 | * We cannot submit those pages together as one BIO. So if our | |
739 | * current logical offset in the file does not equal what would | |
740 | * be the next logical offset in the bio, submit the bio we | |
741 | * have. | |
1da177e4 | 742 | */ |
eb28be2b | 743 | if (sdio->final_block_in_bio != sdio->cur_page_block || |
c2c6ca41 | 744 | cur_offset != bio_next_offset) |
eb28be2b | 745 | dio_bio_submit(dio, sdio); |
1da177e4 LT |
746 | } |
747 | ||
eb28be2b | 748 | if (sdio->bio == NULL) { |
18772641 | 749 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 LT |
750 | if (ret) |
751 | goto out; | |
752 | } | |
753 | ||
1ccf164e | 754 | if (dio_bio_add_page(dio, sdio) != 0) { |
eb28be2b | 755 | dio_bio_submit(dio, sdio); |
18772641 | 756 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 | 757 | if (ret == 0) { |
1ccf164e | 758 | ret = dio_bio_add_page(dio, sdio); |
1da177e4 LT |
759 | BUG_ON(ret != 0); |
760 | } | |
761 | } | |
762 | out: | |
763 | return ret; | |
764 | } | |
765 | ||
766 | /* | |
767 | * An autonomous function to put a chunk of a page under deferred IO. | |
768 | * | |
769 | * The caller doesn't actually know (or care) whether this piece of page is in | |
770 | * a BIO, or is under IO or whatever. We just take care of all possible | |
771 | * situations here. The separation between the logic of do_direct_IO() and | |
772 | * that of submit_page_section() is important for clarity. Please don't break. | |
773 | * | |
774 | * The chunk of page starts on-disk at blocknr. | |
775 | * | |
776 | * We perform deferred IO, by recording the last-submitted page inside our | |
777 | * private part of the dio structure. If possible, we just expand the IO | |
778 | * across that page here. | |
779 | * | |
780 | * If that doesn't work out then we put the old page into the bio and add this | |
781 | * page to the dio instead. | |
782 | */ | |
ba253fbf | 783 | static inline int |
eb28be2b | 784 | submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, |
18772641 AK |
785 | unsigned offset, unsigned len, sector_t blocknr, |
786 | struct buffer_head *map_bh) | |
1da177e4 | 787 | { |
c6293eac | 788 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
1da177e4 | 789 | int ret = 0; |
df41872b | 790 | int boundary = sdio->boundary; /* dio_send_cur_page may clear it */ |
1da177e4 | 791 | |
c6293eac | 792 | if (dio_op == REQ_OP_WRITE) { |
98c4d57d AM |
793 | /* |
794 | * Read accounting is performed in submit_bio() | |
795 | */ | |
796 | task_io_account_write(len); | |
797 | } | |
798 | ||
1da177e4 LT |
799 | /* |
800 | * Can we just grow the current page's presence in the dio? | |
801 | */ | |
eb28be2b AK |
802 | if (sdio->cur_page == page && |
803 | sdio->cur_page_offset + sdio->cur_page_len == offset && | |
804 | sdio->cur_page_block + | |
805 | (sdio->cur_page_len >> sdio->blkbits) == blocknr) { | |
806 | sdio->cur_page_len += len; | |
1da177e4 LT |
807 | goto out; |
808 | } | |
809 | ||
810 | /* | |
811 | * If there's a deferred page already there then send it. | |
812 | */ | |
eb28be2b | 813 | if (sdio->cur_page) { |
18772641 | 814 | ret = dio_send_cur_page(dio, sdio, map_bh); |
1ccf164e | 815 | dio_unpin_page(dio, sdio->cur_page); |
eb28be2b | 816 | sdio->cur_page = NULL; |
1da177e4 | 817 | if (ret) |
b1058b98 | 818 | return ret; |
1da177e4 LT |
819 | } |
820 | ||
1ccf164e | 821 | dio_pin_page(dio, page); /* It is in dio */ |
eb28be2b AK |
822 | sdio->cur_page = page; |
823 | sdio->cur_page_offset = offset; | |
824 | sdio->cur_page_len = len; | |
825 | sdio->cur_page_block = blocknr; | |
826 | sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits; | |
1da177e4 | 827 | out: |
b1058b98 | 828 | /* |
df41872b | 829 | * If boundary then we want to schedule the IO now to |
b1058b98 JK |
830 | * avoid metadata seeks. |
831 | */ | |
df41872b | 832 | if (boundary) { |
b1058b98 | 833 | ret = dio_send_cur_page(dio, sdio, map_bh); |
899f0429 AG |
834 | if (sdio->bio) |
835 | dio_bio_submit(dio, sdio); | |
1ccf164e | 836 | dio_unpin_page(dio, sdio->cur_page); |
b1058b98 JK |
837 | sdio->cur_page = NULL; |
838 | } | |
1da177e4 LT |
839 | return ret; |
840 | } | |
841 | ||
1da177e4 LT |
842 | /* |
843 | * If we are not writing the entire block and get_block() allocated | |
844 | * the block for us, we need to fill-in the unused portion of the | |
845 | * block with zeros. This happens only if user-buffer, fileoffset or | |
846 | * io length is not filesystem block-size multiple. | |
847 | * | |
848 | * `end' is zero if we're doing the start of the IO, 1 at the end of the | |
849 | * IO. | |
850 | */ | |
ba253fbf AK |
851 | static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio, |
852 | int end, struct buffer_head *map_bh) | |
1da177e4 LT |
853 | { |
854 | unsigned dio_blocks_per_fs_block; | |
855 | unsigned this_chunk_blocks; /* In dio_blocks */ | |
856 | unsigned this_chunk_bytes; | |
857 | struct page *page; | |
858 | ||
eb28be2b | 859 | sdio->start_zero_done = 1; |
18772641 | 860 | if (!sdio->blkfactor || !buffer_new(map_bh)) |
1da177e4 LT |
861 | return; |
862 | ||
eb28be2b AK |
863 | dio_blocks_per_fs_block = 1 << sdio->blkfactor; |
864 | this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1); | |
1da177e4 LT |
865 | |
866 | if (!this_chunk_blocks) | |
867 | return; | |
868 | ||
869 | /* | |
870 | * We need to zero out part of an fs block. It is either at the | |
871 | * beginning or the end of the fs block. | |
872 | */ | |
873 | if (end) | |
874 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; | |
875 | ||
eb28be2b | 876 | this_chunk_bytes = this_chunk_blocks << sdio->blkbits; |
1da177e4 | 877 | |
557ed1fa | 878 | page = ZERO_PAGE(0); |
eb28be2b | 879 | if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes, |
18772641 | 880 | sdio->next_block_for_io, map_bh)) |
1da177e4 LT |
881 | return; |
882 | ||
eb28be2b | 883 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 LT |
884 | } |
885 | ||
886 | /* | |
887 | * Walk the user pages, and the file, mapping blocks to disk and generating | |
888 | * a sequence of (page,offset,len,block) mappings. These mappings are injected | |
889 | * into submit_page_section(), which takes care of the next stage of submission | |
890 | * | |
891 | * Direct IO against a blockdev is different from a file. Because we can | |
892 | * happily perform page-sized but 512-byte aligned IOs. It is important that | |
893 | * blockdev IO be able to have fine alignment and large sizes. | |
894 | * | |
1d8fa7a2 | 895 | * So what we do is to permit the ->get_block function to populate bh.b_size |
1da177e4 LT |
896 | * with the size of IO which is permitted at this offset and this i_blkbits. |
897 | * | |
898 | * For best results, the blockdev should be set up with 512-byte i_blkbits and | |
1d8fa7a2 | 899 | * it should set b_size to PAGE_SIZE or more inside get_block(). This gives |
1da177e4 LT |
900 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
901 | */ | |
18772641 AK |
902 | static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, |
903 | struct buffer_head *map_bh) | |
1da177e4 | 904 | { |
c6293eac | 905 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
eb28be2b | 906 | const unsigned blkbits = sdio->blkbits; |
dd545b52 | 907 | const unsigned i_blkbits = blkbits + sdio->blkfactor; |
1da177e4 LT |
908 | int ret = 0; |
909 | ||
eb28be2b | 910 | while (sdio->block_in_file < sdio->final_block_in_request) { |
7b2c99d1 AV |
911 | struct page *page; |
912 | size_t from, to; | |
6fcc5420 BH |
913 | |
914 | page = dio_get_page(dio, sdio); | |
1da177e4 LT |
915 | if (IS_ERR(page)) { |
916 | ret = PTR_ERR(page); | |
917 | goto out; | |
918 | } | |
6fcc5420 BH |
919 | from = sdio->head ? 0 : sdio->from; |
920 | to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE; | |
921 | sdio->head++; | |
1da177e4 | 922 | |
7b2c99d1 | 923 | while (from < to) { |
1da177e4 LT |
924 | unsigned this_chunk_bytes; /* # of bytes mapped */ |
925 | unsigned this_chunk_blocks; /* # of blocks */ | |
926 | unsigned u; | |
927 | ||
eb28be2b | 928 | if (sdio->blocks_available == 0) { |
1da177e4 LT |
929 | /* |
930 | * Need to go and map some more disk | |
931 | */ | |
932 | unsigned long blkmask; | |
933 | unsigned long dio_remainder; | |
934 | ||
18772641 | 935 | ret = get_more_blocks(dio, sdio, map_bh); |
1da177e4 | 936 | if (ret) { |
1ccf164e | 937 | dio_unpin_page(dio, page); |
1da177e4 LT |
938 | goto out; |
939 | } | |
940 | if (!buffer_mapped(map_bh)) | |
941 | goto do_holes; | |
942 | ||
eb28be2b | 943 | sdio->blocks_available = |
f734c89c | 944 | map_bh->b_size >> blkbits; |
eb28be2b AK |
945 | sdio->next_block_for_io = |
946 | map_bh->b_blocknr << sdio->blkfactor; | |
f734c89c JK |
947 | if (buffer_new(map_bh)) { |
948 | clean_bdev_aliases( | |
949 | map_bh->b_bdev, | |
950 | map_bh->b_blocknr, | |
dd545b52 | 951 | map_bh->b_size >> i_blkbits); |
f734c89c | 952 | } |
1da177e4 | 953 | |
eb28be2b | 954 | if (!sdio->blkfactor) |
1da177e4 LT |
955 | goto do_holes; |
956 | ||
eb28be2b AK |
957 | blkmask = (1 << sdio->blkfactor) - 1; |
958 | dio_remainder = (sdio->block_in_file & blkmask); | |
1da177e4 LT |
959 | |
960 | /* | |
961 | * If we are at the start of IO and that IO | |
962 | * starts partway into a fs-block, | |
963 | * dio_remainder will be non-zero. If the IO | |
964 | * is a read then we can simply advance the IO | |
965 | * cursor to the first block which is to be | |
966 | * read. But if the IO is a write and the | |
967 | * block was newly allocated we cannot do that; | |
968 | * the start of the fs block must be zeroed out | |
969 | * on-disk | |
970 | */ | |
971 | if (!buffer_new(map_bh)) | |
eb28be2b AK |
972 | sdio->next_block_for_io += dio_remainder; |
973 | sdio->blocks_available -= dio_remainder; | |
1da177e4 LT |
974 | } |
975 | do_holes: | |
976 | /* Handle holes */ | |
977 | if (!buffer_mapped(map_bh)) { | |
35dc8161 | 978 | loff_t i_size_aligned; |
1da177e4 LT |
979 | |
980 | /* AKPM: eargh, -ENOTBLK is a hack */ | |
c6293eac | 981 | if (dio_op == REQ_OP_WRITE) { |
1ccf164e | 982 | dio_unpin_page(dio, page); |
1da177e4 LT |
983 | return -ENOTBLK; |
984 | } | |
985 | ||
35dc8161 JM |
986 | /* |
987 | * Be sure to account for a partial block as the | |
988 | * last block in the file | |
989 | */ | |
990 | i_size_aligned = ALIGN(i_size_read(dio->inode), | |
991 | 1 << blkbits); | |
eb28be2b | 992 | if (sdio->block_in_file >= |
35dc8161 | 993 | i_size_aligned >> blkbits) { |
1da177e4 | 994 | /* We hit eof */ |
1ccf164e | 995 | dio_unpin_page(dio, page); |
1da177e4 LT |
996 | goto out; |
997 | } | |
7b2c99d1 | 998 | zero_user(page, from, 1 << blkbits); |
eb28be2b | 999 | sdio->block_in_file++; |
7b2c99d1 | 1000 | from += 1 << blkbits; |
3320c60b | 1001 | dio->result += 1 << blkbits; |
1da177e4 LT |
1002 | goto next_block; |
1003 | } | |
1004 | ||
1005 | /* | |
1006 | * If we're performing IO which has an alignment which | |
1007 | * is finer than the underlying fs, go check to see if | |
1008 | * we must zero out the start of this block. | |
1009 | */ | |
eb28be2b | 1010 | if (unlikely(sdio->blkfactor && !sdio->start_zero_done)) |
18772641 | 1011 | dio_zero_block(dio, sdio, 0, map_bh); |
1da177e4 LT |
1012 | |
1013 | /* | |
1014 | * Work out, in this_chunk_blocks, how much disk we | |
1015 | * can add to this page | |
1016 | */ | |
eb28be2b | 1017 | this_chunk_blocks = sdio->blocks_available; |
7b2c99d1 | 1018 | u = (to - from) >> blkbits; |
1da177e4 LT |
1019 | if (this_chunk_blocks > u) |
1020 | this_chunk_blocks = u; | |
eb28be2b | 1021 | u = sdio->final_block_in_request - sdio->block_in_file; |
1da177e4 LT |
1022 | if (this_chunk_blocks > u) |
1023 | this_chunk_blocks = u; | |
1024 | this_chunk_bytes = this_chunk_blocks << blkbits; | |
1025 | BUG_ON(this_chunk_bytes == 0); | |
1026 | ||
092c8d46 JK |
1027 | if (this_chunk_blocks == sdio->blocks_available) |
1028 | sdio->boundary = buffer_boundary(map_bh); | |
eb28be2b | 1029 | ret = submit_page_section(dio, sdio, page, |
7b2c99d1 | 1030 | from, |
eb28be2b | 1031 | this_chunk_bytes, |
18772641 AK |
1032 | sdio->next_block_for_io, |
1033 | map_bh); | |
1da177e4 | 1034 | if (ret) { |
1ccf164e | 1035 | dio_unpin_page(dio, page); |
1da177e4 LT |
1036 | goto out; |
1037 | } | |
eb28be2b | 1038 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 | 1039 | |
eb28be2b | 1040 | sdio->block_in_file += this_chunk_blocks; |
7b2c99d1 AV |
1041 | from += this_chunk_bytes; |
1042 | dio->result += this_chunk_bytes; | |
eb28be2b | 1043 | sdio->blocks_available -= this_chunk_blocks; |
1da177e4 | 1044 | next_block: |
eb28be2b AK |
1045 | BUG_ON(sdio->block_in_file > sdio->final_block_in_request); |
1046 | if (sdio->block_in_file == sdio->final_block_in_request) | |
1da177e4 LT |
1047 | break; |
1048 | } | |
1049 | ||
1ccf164e DH |
1050 | /* Drop the pin which was taken in get_user_pages() */ |
1051 | dio_unpin_page(dio, page); | |
1da177e4 LT |
1052 | } |
1053 | out: | |
1054 | return ret; | |
1055 | } | |
1056 | ||
847cc637 | 1057 | static inline int drop_refcount(struct dio *dio) |
1da177e4 | 1058 | { |
847cc637 | 1059 | int ret2; |
5eb6c7a2 | 1060 | unsigned long flags; |
1da177e4 | 1061 | |
8459d86a ZB |
1062 | /* |
1063 | * Sync will always be dropping the final ref and completing the | |
5eb6c7a2 ZB |
1064 | * operation. AIO can if it was a broken operation described above or |
1065 | * in fact if all the bios race to complete before we get here. In | |
1066 | * that case dio_complete() translates the EIOCBQUEUED into the proper | |
04b2fa9f | 1067 | * return code that the caller will hand to ->complete(). |
5eb6c7a2 ZB |
1068 | * |
1069 | * This is managed by the bio_lock instead of being an atomic_t so that | |
1070 | * completion paths can drop their ref and use the remaining count to | |
1071 | * decide to wake the submission path atomically. | |
8459d86a | 1072 | */ |
5eb6c7a2 ZB |
1073 | spin_lock_irqsave(&dio->bio_lock, flags); |
1074 | ret2 = --dio->refcount; | |
1075 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
847cc637 | 1076 | return ret2; |
1da177e4 LT |
1077 | } |
1078 | ||
eafdc7d1 CH |
1079 | /* |
1080 | * This is a library function for use by filesystem drivers. | |
1081 | * | |
1082 | * The locking rules are governed by the flags parameter: | |
1083 | * - if the flags value contains DIO_LOCKING we use a fancy locking | |
1084 | * scheme for dumb filesystems. | |
1085 | * For writes this function is called under i_mutex and returns with | |
1086 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | |
1087 | * taken and dropped again before returning. | |
eafdc7d1 CH |
1088 | * - if the flags value does NOT contain DIO_LOCKING we don't use any |
1089 | * internal locking but rather rely on the filesystem to synchronize | |
1090 | * direct I/O reads/writes versus each other and truncate. | |
df2d6f26 CH |
1091 | * |
1092 | * To help with locking against truncate we incremented the i_dio_count | |
1093 | * counter before starting direct I/O, and decrement it once we are done. | |
1094 | * Truncate can wait for it to reach zero to provide exclusion. It is | |
1095 | * expected that filesystem provide exclusion between new direct I/O | |
1096 | * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, | |
1097 | * but other filesystems need to take care of this on their own. | |
ba253fbf AK |
1098 | * |
1099 | * NOTE: if you pass "sdio" to anything by pointer make sure that function | |
1100 | * is always inlined. Otherwise gcc is unable to split the structure into | |
1101 | * individual fields and will generate much worse code. This is important | |
1102 | * for the whole file. | |
eafdc7d1 | 1103 | */ |
c22198e7 CH |
1104 | ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, |
1105 | struct block_device *bdev, struct iov_iter *iter, | |
1106 | get_block_t get_block, dio_iodone_t end_io, | |
0aaf08de | 1107 | int flags) |
1da177e4 | 1108 | { |
6aa7de05 | 1109 | unsigned i_blkbits = READ_ONCE(inode->i_blkbits); |
ab73857e | 1110 | unsigned blkbits = i_blkbits; |
1da177e4 LT |
1111 | unsigned blocksize_mask = (1 << blkbits) - 1; |
1112 | ssize_t retval = -EINVAL; | |
1c0ff0f1 | 1113 | const size_t count = iov_iter_count(iter); |
c8b8e32d | 1114 | loff_t offset = iocb->ki_pos; |
1c0ff0f1 | 1115 | const loff_t end = offset + count; |
1da177e4 | 1116 | struct dio *dio; |
eb28be2b | 1117 | struct dio_submit sdio = { 0, }; |
847cc637 | 1118 | struct buffer_head map_bh = { 0, }; |
647d1e4c | 1119 | struct blk_plug plug; |
886a3911 | 1120 | unsigned long align = offset | iov_iter_alignment(iter); |
1da177e4 | 1121 | |
65dd2aa9 AK |
1122 | /* |
1123 | * Avoid references to bdev if not absolutely needed to give | |
1124 | * the early prefetch in the caller enough time. | |
1125 | */ | |
1da177e4 | 1126 | |
f9b5570d | 1127 | /* watch out for a 0 len io from a tricksy fs */ |
1c0ff0f1 | 1128 | if (iov_iter_rw(iter) == READ && !count) |
f9b5570d CH |
1129 | return 0; |
1130 | ||
6e8267f5 | 1131 | dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); |
1da177e4 | 1132 | if (!dio) |
46d71602 | 1133 | return -ENOMEM; |
23aee091 JM |
1134 | /* |
1135 | * Believe it or not, zeroing out the page array caused a .5% | |
1136 | * performance regression in a database benchmark. So, we take | |
1137 | * care to only zero out what's needed. | |
1138 | */ | |
1139 | memset(dio, 0, offsetof(struct dio, pages)); | |
1da177e4 | 1140 | |
5fe878ae | 1141 | dio->flags = flags; |
0a9164cb GKB |
1142 | if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) { |
1143 | /* will be released by direct_io_worker */ | |
1144 | inode_lock(inode); | |
1da177e4 | 1145 | } |
1ccf164e | 1146 | dio->is_pinned = iov_iter_extract_will_pin(iter); |
1da177e4 | 1147 | |
74cedf9b JK |
1148 | /* Once we sampled i_size check for reads beyond EOF */ |
1149 | dio->i_size = i_size_read(inode); | |
1150 | if (iov_iter_rw(iter) == READ && offset >= dio->i_size) { | |
2d4594ac | 1151 | retval = 0; |
46d71602 | 1152 | goto fail_dio; |
74cedf9b JK |
1153 | } |
1154 | ||
41b21af3 GKB |
1155 | if (align & blocksize_mask) { |
1156 | if (bdev) | |
1157 | blkbits = blksize_bits(bdev_logical_block_size(bdev)); | |
1158 | blocksize_mask = (1 << blkbits) - 1; | |
1159 | if (align & blocksize_mask) | |
1160 | goto fail_dio; | |
1161 | } | |
1162 | ||
0a9164cb GKB |
1163 | if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) { |
1164 | struct address_space *mapping = iocb->ki_filp->f_mapping; | |
1165 | ||
1166 | retval = filemap_write_and_wait_range(mapping, offset, end - 1); | |
1167 | if (retval) | |
1168 | goto fail_dio; | |
74cedf9b JK |
1169 | } |
1170 | ||
1da177e4 | 1171 | /* |
60392573 CH |
1172 | * For file extending writes updating i_size before data writeouts |
1173 | * complete can expose uninitialized blocks in dumb filesystems. | |
1174 | * In that case we need to wait for I/O completion even if asked | |
1175 | * for an asynchronous write. | |
1da177e4 | 1176 | */ |
60392573 CH |
1177 | if (is_sync_kiocb(iocb)) |
1178 | dio->is_async = false; | |
c8f4c36f | 1179 | else if (iov_iter_rw(iter) == WRITE && end > i_size_read(inode)) |
60392573 CH |
1180 | dio->is_async = false; |
1181 | else | |
1182 | dio->is_async = true; | |
1183 | ||
847cc637 | 1184 | dio->inode = inode; |
8a4c1e42 | 1185 | if (iov_iter_rw(iter) == WRITE) { |
c6293eac | 1186 | dio->opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE; |
03a07c92 | 1187 | if (iocb->ki_flags & IOCB_NOWAIT) |
c6293eac | 1188 | dio->opf |= REQ_NOWAIT; |
8a4c1e42 | 1189 | } else { |
c6293eac | 1190 | dio->opf = REQ_OP_READ; |
8a4c1e42 | 1191 | } |
02afc27f CH |
1192 | |
1193 | /* | |
1194 | * For AIO O_(D)SYNC writes we need to defer completions to a workqueue | |
1195 | * so that we can call ->fsync. | |
1196 | */ | |
332391a9 LC |
1197 | if (dio->is_async && iov_iter_rw(iter) == WRITE) { |
1198 | retval = 0; | |
91b94c5d | 1199 | if (iocb_is_dsync(iocb)) |
332391a9 LC |
1200 | retval = dio_set_defer_completion(dio); |
1201 | else if (!dio->inode->i_sb->s_dio_done_wq) { | |
1202 | /* | |
1203 | * In case of AIO write racing with buffered read we | |
1204 | * need to defer completion. We can't decide this now, | |
1205 | * however the workqueue needs to be initialized here. | |
1206 | */ | |
1207 | retval = sb_init_dio_done_wq(dio->inode->i_sb); | |
1208 | } | |
46d71602 GKB |
1209 | if (retval) |
1210 | goto fail_dio; | |
02afc27f CH |
1211 | } |
1212 | ||
1213 | /* | |
1214 | * Will be decremented at I/O completion time. | |
1215 | */ | |
ce3077ee | 1216 | inode_dio_begin(inode); |
02afc27f CH |
1217 | |
1218 | retval = 0; | |
847cc637 | 1219 | sdio.blkbits = blkbits; |
ab73857e | 1220 | sdio.blkfactor = i_blkbits - blkbits; |
847cc637 AK |
1221 | sdio.block_in_file = offset >> blkbits; |
1222 | ||
1223 | sdio.get_block = get_block; | |
1224 | dio->end_io = end_io; | |
847cc637 AK |
1225 | sdio.final_block_in_bio = -1; |
1226 | sdio.next_block_for_io = -1; | |
1227 | ||
1228 | dio->iocb = iocb; | |
847cc637 AK |
1229 | |
1230 | spin_lock_init(&dio->bio_lock); | |
1231 | dio->refcount = 1; | |
1232 | ||
fcb14cb1 | 1233 | dio->should_dirty = user_backed_iter(iter) && iov_iter_rw(iter) == READ; |
7b2c99d1 | 1234 | sdio.iter = iter; |
1c0ff0f1 | 1235 | sdio.final_block_in_request = end >> blkbits; |
7b2c99d1 | 1236 | |
847cc637 AK |
1237 | /* |
1238 | * In case of non-aligned buffers, we may need 2 more | |
1239 | * pages since we need to zero out first and last block. | |
1240 | */ | |
1241 | if (unlikely(sdio.blkfactor)) | |
1242 | sdio.pages_in_io = 2; | |
1243 | ||
f67da30c | 1244 | sdio.pages_in_io += iov_iter_npages(iter, INT_MAX); |
847cc637 | 1245 | |
647d1e4c FW |
1246 | blk_start_plug(&plug); |
1247 | ||
7b2c99d1 AV |
1248 | retval = do_direct_IO(dio, &sdio, &map_bh); |
1249 | if (retval) | |
1250 | dio_cleanup(dio, &sdio); | |
847cc637 AK |
1251 | |
1252 | if (retval == -ENOTBLK) { | |
1253 | /* | |
1254 | * The remaining part of the request will be | |
3d742d4b | 1255 | * handled by buffered I/O when we return |
847cc637 AK |
1256 | */ |
1257 | retval = 0; | |
1258 | } | |
1259 | /* | |
1260 | * There may be some unwritten disk at the end of a part-written | |
1261 | * fs-block-sized block. Go zero that now. | |
1262 | */ | |
1263 | dio_zero_block(dio, &sdio, 1, &map_bh); | |
1264 | ||
1265 | if (sdio.cur_page) { | |
1266 | ssize_t ret2; | |
1267 | ||
1268 | ret2 = dio_send_cur_page(dio, &sdio, &map_bh); | |
1269 | if (retval == 0) | |
1270 | retval = ret2; | |
1ccf164e | 1271 | dio_unpin_page(dio, sdio.cur_page); |
847cc637 AK |
1272 | sdio.cur_page = NULL; |
1273 | } | |
1274 | if (sdio.bio) | |
1275 | dio_bio_submit(dio, &sdio); | |
1276 | ||
647d1e4c FW |
1277 | blk_finish_plug(&plug); |
1278 | ||
847cc637 AK |
1279 | /* |
1280 | * It is possible that, we return short IO due to end of file. | |
1281 | * In that case, we need to release all the pages we got hold on. | |
1282 | */ | |
1283 | dio_cleanup(dio, &sdio); | |
1284 | ||
1285 | /* | |
1286 | * All block lookups have been performed. For READ requests | |
1287 | * we can let i_mutex go now that its achieved its purpose | |
1288 | * of protecting us from looking up uninitialized blocks. | |
1289 | */ | |
17f8c842 | 1290 | if (iov_iter_rw(iter) == READ && (dio->flags & DIO_LOCKING)) |
5955102c | 1291 | inode_unlock(dio->inode); |
847cc637 AK |
1292 | |
1293 | /* | |
1294 | * The only time we want to leave bios in flight is when a successful | |
1295 | * partial aio read or full aio write have been setup. In that case | |
1296 | * bio completion will call aio_complete. The only time it's safe to | |
1297 | * call aio_complete is when we return -EIOCBQUEUED, so we key on that. | |
1298 | * This had *better* be the only place that raises -EIOCBQUEUED. | |
1299 | */ | |
1300 | BUG_ON(retval == -EIOCBQUEUED); | |
1301 | if (dio->is_async && retval == 0 && dio->result && | |
17f8c842 | 1302 | (iov_iter_rw(iter) == READ || dio->result == count)) |
847cc637 | 1303 | retval = -EIOCBQUEUED; |
af436472 | 1304 | else |
847cc637 AK |
1305 | dio_await_completion(dio); |
1306 | ||
1307 | if (drop_refcount(dio) == 0) { | |
ffe51f01 | 1308 | retval = dio_complete(dio, retval, DIO_COMPLETE_INVALIDATE); |
847cc637 AK |
1309 | } else |
1310 | BUG_ON(retval != -EIOCBQUEUED); | |
1da177e4 | 1311 | |
46d71602 GKB |
1312 | return retval; |
1313 | ||
1314 | fail_dio: | |
1315 | if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) | |
1316 | inode_unlock(inode); | |
1317 | ||
1318 | kmem_cache_free(dio_cache, dio); | |
7bb46a67 | 1319 | return retval; |
1320 | } | |
1da177e4 | 1321 | EXPORT_SYMBOL(__blockdev_direct_IO); |
6e8267f5 AK |
1322 | |
1323 | static __init int dio_init(void) | |
1324 | { | |
1325 | dio_cache = KMEM_CACHE(dio, SLAB_PANIC); | |
1326 | return 0; | |
1327 | } | |
1328 | module_init(dio_init) |