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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 LT |
44 | /* |
45 | * How many user pages to map in one call to get_user_pages(). This determines | |
cde1ecb3 | 46 | * 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 */ | |
eb28be2b | 124 | |
18772641 | 125 | void *private; /* copy from map_bh.b_private */ |
eb28be2b AK |
126 | |
127 | /* BIO completion state */ | |
128 | spinlock_t bio_lock; /* protects BIO fields below */ | |
0dc2bc49 AK |
129 | int page_errors; /* errno from get_user_pages() */ |
130 | int is_async; /* is IO async ? */ | |
7b7a8665 | 131 | bool defer_completion; /* defer AIO completion to workqueue? */ |
53cbf3b1 | 132 | bool should_dirty; /* if pages should be dirtied */ |
0dc2bc49 | 133 | int io_error; /* IO error in completion path */ |
eb28be2b AK |
134 | unsigned long refcount; /* direct_io_worker() and bios */ |
135 | struct bio *bio_list; /* singly linked via bi_private */ | |
136 | struct task_struct *waiter; /* waiting task (NULL if none) */ | |
137 | ||
138 | /* AIO related stuff */ | |
139 | struct kiocb *iocb; /* kiocb */ | |
eb28be2b AK |
140 | ssize_t result; /* IO result */ |
141 | ||
23aee091 JM |
142 | /* |
143 | * pages[] (and any fields placed after it) are not zeroed out at | |
144 | * allocation time. Don't add new fields after pages[] unless you | |
145 | * wish that they not be zeroed. | |
146 | */ | |
7b7a8665 CH |
147 | union { |
148 | struct page *pages[DIO_PAGES]; /* page buffer */ | |
149 | struct work_struct complete_work;/* deferred AIO completion */ | |
150 | }; | |
6e8267f5 AK |
151 | } ____cacheline_aligned_in_smp; |
152 | ||
153 | static struct kmem_cache *dio_cache __read_mostly; | |
1da177e4 LT |
154 | |
155 | /* | |
156 | * How many pages are in the queue? | |
157 | */ | |
eb28be2b | 158 | static inline unsigned dio_pages_present(struct dio_submit *sdio) |
1da177e4 | 159 | { |
eb28be2b | 160 | return sdio->tail - sdio->head; |
1da177e4 LT |
161 | } |
162 | ||
163 | /* | |
164 | * Go grab and pin some userspace pages. Typically we'll get 64 at a time. | |
165 | */ | |
ba253fbf | 166 | static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 167 | { |
c6293eac | 168 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
7b2c99d1 | 169 | ssize_t ret; |
1da177e4 | 170 | |
1ef255e2 | 171 | ret = iov_iter_get_pages2(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES, |
7b2c99d1 | 172 | &sdio->from); |
1da177e4 | 173 | |
c6293eac | 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 | 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 | |
204 | * buffered inside the dio so that we can call get_user_pages() against a | |
205 | * decent number of pages, less frequently. To provide nicer use of the | |
206 | * L1 cache. | |
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 | ||
c70d868f | 222 | /* |
6d544bb4 | 223 | * dio_complete() - called when all DIO BIO I/O has been completed |
6d544bb4 | 224 | * |
7b7a8665 CH |
225 | * This drops i_dio_count, lets interested parties know that a DIO operation |
226 | * has completed, and calculates the resulting return code for the operation. | |
6d544bb4 ZB |
227 | * |
228 | * It lets the filesystem know if it registered an interest earlier via | |
229 | * get_block. Pass the private field of the map buffer_head so that | |
230 | * filesystems can use it to hold additional state between get_block calls and | |
231 | * dio_complete. | |
1da177e4 | 232 | */ |
ffe51f01 | 233 | static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags) |
1da177e4 | 234 | { |
c6293eac | 235 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
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 */ | |
c6293eac | 253 | if (dio_op == REQ_OP_READ && |
8a4c1e42 | 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 | 287 | if (flags & DIO_COMPLETE_INVALIDATE && |
c6293eac | 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 | |
c6293eac | 307 | if (ret > 0 && dio_op == REQ_OP_WRITE) |
41e817bc | 308 | ret = generic_write_sync(dio->iocb, ret); |
6b19b766 | 309 | dio->iocb->ki_complete(dio->iocb, ret); |
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; | |
c6293eac | 331 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
5eb6c7a2 ZB |
332 | unsigned long remaining; |
333 | unsigned long flags; | |
332391a9 | 334 | bool defer_completion = false; |
1da177e4 | 335 | |
1da177e4 LT |
336 | /* cleanup the bio */ |
337 | dio_bio_complete(dio, bio); | |
0273201e | 338 | |
5eb6c7a2 ZB |
339 | spin_lock_irqsave(&dio->bio_lock, flags); |
340 | remaining = --dio->refcount; | |
341 | if (remaining == 1 && dio->waiter) | |
20258b2b | 342 | wake_up_process(dio->waiter); |
5eb6c7a2 | 343 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
20258b2b | 344 | |
8459d86a | 345 | if (remaining == 0) { |
332391a9 LC |
346 | /* |
347 | * Defer completion when defer_completion is set or | |
348 | * when the inode has pages mapped and this is AIO write. | |
349 | * We need to invalidate those pages because there is a | |
350 | * chance they contain stale data in the case buffered IO | |
351 | * went in between AIO submission and completion into the | |
352 | * same region. | |
353 | */ | |
354 | if (dio->result) | |
355 | defer_completion = dio->defer_completion || | |
c6293eac | 356 | (dio_op == REQ_OP_WRITE && |
332391a9 LC |
357 | dio->inode->i_mapping->nrpages); |
358 | if (defer_completion) { | |
7b7a8665 CH |
359 | INIT_WORK(&dio->complete_work, dio_aio_complete_work); |
360 | queue_work(dio->inode->i_sb->s_dio_done_wq, | |
361 | &dio->complete_work); | |
362 | } else { | |
ffe51f01 | 363 | dio_complete(dio, 0, DIO_COMPLETE_ASYNC); |
7b7a8665 | 364 | } |
8459d86a | 365 | } |
1da177e4 LT |
366 | } |
367 | ||
368 | /* | |
369 | * The BIO completion handler simply queues the BIO up for the process-context | |
370 | * handler. | |
371 | * | |
372 | * During I/O bi_private points at the dio. After I/O, bi_private is used to | |
373 | * implement a singly-linked list of completed BIOs, at dio->bio_list. | |
374 | */ | |
4246a0b6 | 375 | static void dio_bio_end_io(struct bio *bio) |
1da177e4 LT |
376 | { |
377 | struct dio *dio = bio->bi_private; | |
378 | unsigned long flags; | |
379 | ||
1da177e4 LT |
380 | spin_lock_irqsave(&dio->bio_lock, flags); |
381 | bio->bi_private = dio->bio_list; | |
382 | dio->bio_list = bio; | |
5eb6c7a2 | 383 | if (--dio->refcount == 1 && dio->waiter) |
1da177e4 LT |
384 | wake_up_process(dio->waiter); |
385 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
1da177e4 LT |
386 | } |
387 | ||
ba253fbf | 388 | static inline void |
eb28be2b AK |
389 | dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, |
390 | struct block_device *bdev, | |
391 | sector_t first_sector, int nr_vecs) | |
1da177e4 LT |
392 | { |
393 | struct bio *bio; | |
394 | ||
20d9600c | 395 | /* |
0eb0b63c CH |
396 | * bio_alloc() is guaranteed to return a bio when allowed to sleep and |
397 | * we request a valid number of vectors. | |
20d9600c | 398 | */ |
c6293eac | 399 | bio = bio_alloc(bdev, nr_vecs, dio->opf, GFP_KERNEL); |
4f024f37 | 400 | bio->bi_iter.bi_sector = first_sector; |
1da177e4 LT |
401 | if (dio->is_async) |
402 | bio->bi_end_io = dio_bio_end_aio; | |
403 | else | |
404 | bio->bi_end_io = dio_bio_end_io; | |
eb28be2b AK |
405 | sdio->bio = bio; |
406 | sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; | |
1da177e4 LT |
407 | } |
408 | ||
409 | /* | |
410 | * In the AIO read case we speculatively dirty the pages before starting IO. | |
411 | * During IO completion, any of these pages which happen to have been written | |
412 | * back will be redirtied by bio_check_pages_dirty(). | |
0273201e ZB |
413 | * |
414 | * bios hold a dio reference between submit_bio and ->end_io. | |
1da177e4 | 415 | */ |
ba253fbf | 416 | static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 417 | { |
c6293eac | 418 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
eb28be2b | 419 | struct bio *bio = sdio->bio; |
5eb6c7a2 | 420 | unsigned long flags; |
1da177e4 LT |
421 | |
422 | bio->bi_private = dio; | |
5eb6c7a2 ZB |
423 | |
424 | spin_lock_irqsave(&dio->bio_lock, flags); | |
425 | dio->refcount++; | |
426 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
427 | ||
c6293eac | 428 | if (dio->is_async && dio_op == REQ_OP_READ && dio->should_dirty) |
1da177e4 | 429 | bio_set_pages_dirty(bio); |
5eb6c7a2 | 430 | |
309dca30 | 431 | dio->bio_disk = bio->bi_bdev->bd_disk; |
c1c53460 | 432 | |
0aaf08de | 433 | submit_bio(bio); |
1da177e4 | 434 | |
eb28be2b AK |
435 | sdio->bio = NULL; |
436 | sdio->boundary = 0; | |
437 | sdio->logical_offset_in_bio = 0; | |
1da177e4 LT |
438 | } |
439 | ||
440 | /* | |
441 | * Release any resources in case of a failure | |
442 | */ | |
ba253fbf | 443 | static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 444 | { |
7b2c99d1 | 445 | while (sdio->head < sdio->tail) |
09cbfeaf | 446 | put_page(dio->pages[sdio->head++]); |
1da177e4 LT |
447 | } |
448 | ||
449 | /* | |
0273201e ZB |
450 | * Wait for the next BIO to complete. Remove it and return it. NULL is |
451 | * returned once all BIOs have been completed. This must only be called once | |
452 | * all bios have been issued so that dio->refcount can only decrease. This | |
3d742d4b | 453 | * requires that the caller hold a reference on the dio. |
1da177e4 LT |
454 | */ |
455 | static struct bio *dio_await_one(struct dio *dio) | |
456 | { | |
457 | unsigned long flags; | |
0273201e | 458 | struct bio *bio = NULL; |
1da177e4 LT |
459 | |
460 | spin_lock_irqsave(&dio->bio_lock, flags); | |
5eb6c7a2 ZB |
461 | |
462 | /* | |
463 | * Wait as long as the list is empty and there are bios in flight. bio | |
464 | * completion drops the count, maybe adds to the list, and wakes while | |
465 | * holding the bio_lock so we don't need set_current_state()'s barrier | |
466 | * and can call it after testing our condition. | |
467 | */ | |
468 | while (dio->refcount > 1 && dio->bio_list == NULL) { | |
469 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
470 | dio->waiter = current; | |
471 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
94c2ed58 | 472 | blk_io_schedule(); |
5eb6c7a2 ZB |
473 | /* wake up sets us TASK_RUNNING */ |
474 | spin_lock_irqsave(&dio->bio_lock, flags); | |
475 | dio->waiter = NULL; | |
1da177e4 | 476 | } |
0273201e ZB |
477 | if (dio->bio_list) { |
478 | bio = dio->bio_list; | |
479 | dio->bio_list = bio->bi_private; | |
480 | } | |
1da177e4 LT |
481 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
482 | return bio; | |
483 | } | |
484 | ||
485 | /* | |
486 | * Process one completed BIO. No locks are held. | |
487 | */ | |
4e4cbee9 | 488 | static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio) |
1da177e4 | 489 | { |
4e4cbee9 | 490 | blk_status_t err = bio->bi_status; |
c6293eac BVA |
491 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
492 | bool should_dirty = dio_op == REQ_OP_READ && dio->should_dirty; | |
1da177e4 | 493 | |
03a07c92 GR |
494 | if (err) { |
495 | if (err == BLK_STS_AGAIN && (bio->bi_opf & REQ_NOWAIT)) | |
496 | dio->io_error = -EAGAIN; | |
497 | else | |
498 | dio->io_error = -EIO; | |
499 | } | |
1da177e4 | 500 | |
d7c8aa85 | 501 | if (dio->is_async && should_dirty) { |
7ddc971f | 502 | bio_check_pages_dirty(bio); /* transfers ownership */ |
1da177e4 | 503 | } else { |
d7c8aa85 | 504 | bio_release_pages(bio, should_dirty); |
1da177e4 LT |
505 | bio_put(bio); |
506 | } | |
9b81c842 | 507 | return err; |
1da177e4 LT |
508 | } |
509 | ||
510 | /* | |
0273201e ZB |
511 | * Wait on and process all in-flight BIOs. This must only be called once |
512 | * all bios have been issued so that the refcount can only decrease. | |
513 | * This just waits for all bios to make it through dio_bio_complete. IO | |
beb7dd86 | 514 | * errors are propagated through dio->io_error and should be propagated via |
0273201e | 515 | * dio_complete(). |
1da177e4 | 516 | */ |
6d544bb4 | 517 | static void dio_await_completion(struct dio *dio) |
1da177e4 | 518 | { |
0273201e ZB |
519 | struct bio *bio; |
520 | do { | |
521 | bio = dio_await_one(dio); | |
522 | if (bio) | |
523 | dio_bio_complete(dio, bio); | |
524 | } while (bio); | |
1da177e4 LT |
525 | } |
526 | ||
527 | /* | |
528 | * A really large O_DIRECT read or write can generate a lot of BIOs. So | |
529 | * to keep the memory consumption sane we periodically reap any completed BIOs | |
530 | * during the BIO generation phase. | |
531 | * | |
532 | * This also helps to limit the peak amount of pinned userspace memory. | |
533 | */ | |
ba253fbf | 534 | static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
535 | { |
536 | int ret = 0; | |
537 | ||
eb28be2b | 538 | if (sdio->reap_counter++ >= 64) { |
1da177e4 LT |
539 | while (dio->bio_list) { |
540 | unsigned long flags; | |
541 | struct bio *bio; | |
542 | int ret2; | |
543 | ||
544 | spin_lock_irqsave(&dio->bio_lock, flags); | |
545 | bio = dio->bio_list; | |
546 | dio->bio_list = bio->bi_private; | |
547 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
4e4cbee9 | 548 | ret2 = blk_status_to_errno(dio_bio_complete(dio, bio)); |
1da177e4 LT |
549 | if (ret == 0) |
550 | ret = ret2; | |
551 | } | |
eb28be2b | 552 | sdio->reap_counter = 0; |
1da177e4 LT |
553 | } |
554 | return ret; | |
555 | } | |
556 | ||
7b7a8665 CH |
557 | static int dio_set_defer_completion(struct dio *dio) |
558 | { | |
559 | struct super_block *sb = dio->inode->i_sb; | |
560 | ||
561 | if (dio->defer_completion) | |
562 | return 0; | |
563 | dio->defer_completion = true; | |
564 | if (!sb->s_dio_done_wq) | |
565 | return sb_init_dio_done_wq(sb); | |
566 | return 0; | |
567 | } | |
568 | ||
1da177e4 LT |
569 | /* |
570 | * Call into the fs to map some more disk blocks. We record the current number | |
eb28be2b | 571 | * of available blocks at sdio->blocks_available. These are in units of the |
93407472 | 572 | * fs blocksize, i_blocksize(inode). |
1da177e4 LT |
573 | * |
574 | * The fs is allowed to map lots of blocks at once. If it wants to do that, | |
575 | * it uses the passed inode-relative block number as the file offset, as usual. | |
576 | * | |
1d8fa7a2 | 577 | * get_block() is passed the number of i_blkbits-sized blocks which direct_io |
1da177e4 LT |
578 | * has remaining to do. The fs should not map more than this number of blocks. |
579 | * | |
580 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to | |
581 | * indicate how much contiguous disk space has been made available at | |
582 | * bh->b_blocknr. | |
583 | * | |
584 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). | |
585 | * This isn't very efficient... | |
586 | * | |
587 | * In the case of filesystem holes: the fs may return an arbitrarily-large | |
588 | * hole by returning an appropriate value in b_size and by clearing | |
589 | * buffer_mapped(). However the direct-io code will only process holes one | |
1d8fa7a2 | 590 | * block at a time - it will repeatedly call get_block() as it walks the hole. |
1da177e4 | 591 | */ |
18772641 AK |
592 | static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, |
593 | struct buffer_head *map_bh) | |
1da177e4 | 594 | { |
c6293eac | 595 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
1da177e4 | 596 | int ret; |
1da177e4 | 597 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ |
ae55e1aa | 598 | sector_t fs_endblk; /* Into file, in filesystem-sized blocks */ |
1da177e4 | 599 | unsigned long fs_count; /* Number of filesystem-sized blocks */ |
1da177e4 | 600 | int create; |
ab73857e | 601 | unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor; |
8b9433eb | 602 | loff_t i_size; |
1da177e4 LT |
603 | |
604 | /* | |
605 | * If there was a memory error and we've overwritten all the | |
606 | * mapped blocks then we can now return that memory error | |
607 | */ | |
608 | ret = dio->page_errors; | |
609 | if (ret == 0) { | |
eb28be2b AK |
610 | BUG_ON(sdio->block_in_file >= sdio->final_block_in_request); |
611 | fs_startblk = sdio->block_in_file >> sdio->blkfactor; | |
ae55e1aa TM |
612 | fs_endblk = (sdio->final_block_in_request - 1) >> |
613 | sdio->blkfactor; | |
614 | fs_count = fs_endblk - fs_startblk + 1; | |
1da177e4 | 615 | |
3c674e74 | 616 | map_bh->b_state = 0; |
ab73857e | 617 | map_bh->b_size = fs_count << i_blkbits; |
3c674e74 | 618 | |
5fe878ae | 619 | /* |
9ecd10b7 EG |
620 | * For writes that could fill holes inside i_size on a |
621 | * DIO_SKIP_HOLES filesystem we forbid block creations: only | |
622 | * overwrites are permitted. We will return early to the caller | |
623 | * once we see an unmapped buffer head returned, and the caller | |
624 | * will fall back to buffered I/O. | |
5fe878ae CH |
625 | * |
626 | * Otherwise the decision is left to the get_blocks method, | |
627 | * which may decide to handle it or also return an unmapped | |
628 | * buffer head. | |
629 | */ | |
c6293eac | 630 | create = dio_op == REQ_OP_WRITE; |
5fe878ae | 631 | if (dio->flags & DIO_SKIP_HOLES) { |
8b9433eb EF |
632 | i_size = i_size_read(dio->inode); |
633 | if (i_size && fs_startblk <= (i_size - 1) >> i_blkbits) | |
1da177e4 | 634 | create = 0; |
1da177e4 | 635 | } |
3c674e74 | 636 | |
eb28be2b | 637 | ret = (*sdio->get_block)(dio->inode, fs_startblk, |
1da177e4 | 638 | map_bh, create); |
18772641 AK |
639 | |
640 | /* Store for completion */ | |
641 | dio->private = map_bh->b_private; | |
7b7a8665 CH |
642 | |
643 | if (ret == 0 && buffer_defer_completion(map_bh)) | |
644 | ret = dio_set_defer_completion(dio); | |
1da177e4 LT |
645 | } |
646 | return ret; | |
647 | } | |
648 | ||
649 | /* | |
650 | * There is no bio. Make one now. | |
651 | */ | |
ba253fbf AK |
652 | static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio, |
653 | sector_t start_sector, struct buffer_head *map_bh) | |
1da177e4 LT |
654 | { |
655 | sector_t sector; | |
656 | int ret, nr_pages; | |
657 | ||
eb28be2b | 658 | ret = dio_bio_reap(dio, sdio); |
1da177e4 LT |
659 | if (ret) |
660 | goto out; | |
eb28be2b | 661 | sector = start_sector << (sdio->blkbits - 9); |
5f7136db | 662 | nr_pages = bio_max_segs(sdio->pages_in_io); |
1da177e4 | 663 | BUG_ON(nr_pages <= 0); |
18772641 | 664 | dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages); |
eb28be2b | 665 | sdio->boundary = 0; |
1da177e4 LT |
666 | out: |
667 | return ret; | |
668 | } | |
669 | ||
670 | /* | |
671 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If | |
672 | * that was successful then update final_block_in_bio and take a ref against | |
673 | * the just-added page. | |
674 | * | |
675 | * Return zero on success. Non-zero means the caller needs to start a new BIO. | |
676 | */ | |
ba253fbf | 677 | static inline int dio_bio_add_page(struct dio_submit *sdio) |
1da177e4 LT |
678 | { |
679 | int ret; | |
680 | ||
eb28be2b AK |
681 | ret = bio_add_page(sdio->bio, sdio->cur_page, |
682 | sdio->cur_page_len, sdio->cur_page_offset); | |
683 | if (ret == sdio->cur_page_len) { | |
1da177e4 LT |
684 | /* |
685 | * Decrement count only, if we are done with this page | |
686 | */ | |
eb28be2b AK |
687 | if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE) |
688 | sdio->pages_in_io--; | |
09cbfeaf | 689 | get_page(sdio->cur_page); |
eb28be2b AK |
690 | sdio->final_block_in_bio = sdio->cur_page_block + |
691 | (sdio->cur_page_len >> sdio->blkbits); | |
1da177e4 LT |
692 | ret = 0; |
693 | } else { | |
694 | ret = 1; | |
695 | } | |
696 | return ret; | |
697 | } | |
698 | ||
699 | /* | |
700 | * Put cur_page under IO. The section of cur_page which is described by | |
701 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page | |
702 | * starts on-disk at cur_page_block. | |
703 | * | |
704 | * We take a ref against the page here (on behalf of its presence in the bio). | |
705 | * | |
706 | * The caller of this function is responsible for removing cur_page from the | |
707 | * dio, and for dropping the refcount which came from that presence. | |
708 | */ | |
ba253fbf AK |
709 | static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio, |
710 | struct buffer_head *map_bh) | |
1da177e4 LT |
711 | { |
712 | int ret = 0; | |
713 | ||
eb28be2b AK |
714 | if (sdio->bio) { |
715 | loff_t cur_offset = sdio->cur_page_fs_offset; | |
716 | loff_t bio_next_offset = sdio->logical_offset_in_bio + | |
4f024f37 | 717 | sdio->bio->bi_iter.bi_size; |
c2c6ca41 | 718 | |
1da177e4 | 719 | /* |
c2c6ca41 JB |
720 | * See whether this new request is contiguous with the old. |
721 | * | |
f0940cee NK |
722 | * Btrfs cannot handle having logically non-contiguous requests |
723 | * submitted. For example if you have | |
c2c6ca41 JB |
724 | * |
725 | * Logical: [0-4095][HOLE][8192-12287] | |
f0940cee | 726 | * Physical: [0-4095] [4096-8191] |
c2c6ca41 JB |
727 | * |
728 | * We cannot submit those pages together as one BIO. So if our | |
729 | * current logical offset in the file does not equal what would | |
730 | * be the next logical offset in the bio, submit the bio we | |
731 | * have. | |
1da177e4 | 732 | */ |
eb28be2b | 733 | if (sdio->final_block_in_bio != sdio->cur_page_block || |
c2c6ca41 | 734 | cur_offset != bio_next_offset) |
eb28be2b | 735 | dio_bio_submit(dio, sdio); |
1da177e4 LT |
736 | } |
737 | ||
eb28be2b | 738 | if (sdio->bio == NULL) { |
18772641 | 739 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 LT |
740 | if (ret) |
741 | goto out; | |
742 | } | |
743 | ||
eb28be2b AK |
744 | if (dio_bio_add_page(sdio) != 0) { |
745 | dio_bio_submit(dio, sdio); | |
18772641 | 746 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 | 747 | if (ret == 0) { |
eb28be2b | 748 | ret = dio_bio_add_page(sdio); |
1da177e4 LT |
749 | BUG_ON(ret != 0); |
750 | } | |
751 | } | |
752 | out: | |
753 | return ret; | |
754 | } | |
755 | ||
756 | /* | |
757 | * An autonomous function to put a chunk of a page under deferred IO. | |
758 | * | |
759 | * The caller doesn't actually know (or care) whether this piece of page is in | |
760 | * a BIO, or is under IO or whatever. We just take care of all possible | |
761 | * situations here. The separation between the logic of do_direct_IO() and | |
762 | * that of submit_page_section() is important for clarity. Please don't break. | |
763 | * | |
764 | * The chunk of page starts on-disk at blocknr. | |
765 | * | |
766 | * We perform deferred IO, by recording the last-submitted page inside our | |
767 | * private part of the dio structure. If possible, we just expand the IO | |
768 | * across that page here. | |
769 | * | |
770 | * If that doesn't work out then we put the old page into the bio and add this | |
771 | * page to the dio instead. | |
772 | */ | |
ba253fbf | 773 | static inline int |
eb28be2b | 774 | submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, |
18772641 AK |
775 | unsigned offset, unsigned len, sector_t blocknr, |
776 | struct buffer_head *map_bh) | |
1da177e4 | 777 | { |
c6293eac | 778 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
1da177e4 | 779 | int ret = 0; |
df41872b | 780 | int boundary = sdio->boundary; /* dio_send_cur_page may clear it */ |
1da177e4 | 781 | |
c6293eac | 782 | if (dio_op == REQ_OP_WRITE) { |
98c4d57d AM |
783 | /* |
784 | * Read accounting is performed in submit_bio() | |
785 | */ | |
786 | task_io_account_write(len); | |
787 | } | |
788 | ||
1da177e4 LT |
789 | /* |
790 | * Can we just grow the current page's presence in the dio? | |
791 | */ | |
eb28be2b AK |
792 | if (sdio->cur_page == page && |
793 | sdio->cur_page_offset + sdio->cur_page_len == offset && | |
794 | sdio->cur_page_block + | |
795 | (sdio->cur_page_len >> sdio->blkbits) == blocknr) { | |
796 | sdio->cur_page_len += len; | |
1da177e4 LT |
797 | goto out; |
798 | } | |
799 | ||
800 | /* | |
801 | * If there's a deferred page already there then send it. | |
802 | */ | |
eb28be2b | 803 | if (sdio->cur_page) { |
18772641 | 804 | ret = dio_send_cur_page(dio, sdio, map_bh); |
09cbfeaf | 805 | put_page(sdio->cur_page); |
eb28be2b | 806 | sdio->cur_page = NULL; |
1da177e4 | 807 | if (ret) |
b1058b98 | 808 | return ret; |
1da177e4 LT |
809 | } |
810 | ||
09cbfeaf | 811 | get_page(page); /* It is in dio */ |
eb28be2b AK |
812 | sdio->cur_page = page; |
813 | sdio->cur_page_offset = offset; | |
814 | sdio->cur_page_len = len; | |
815 | sdio->cur_page_block = blocknr; | |
816 | sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits; | |
1da177e4 | 817 | out: |
b1058b98 | 818 | /* |
df41872b | 819 | * If boundary then we want to schedule the IO now to |
b1058b98 JK |
820 | * avoid metadata seeks. |
821 | */ | |
df41872b | 822 | if (boundary) { |
b1058b98 | 823 | ret = dio_send_cur_page(dio, sdio, map_bh); |
899f0429 AG |
824 | if (sdio->bio) |
825 | dio_bio_submit(dio, sdio); | |
09cbfeaf | 826 | put_page(sdio->cur_page); |
b1058b98 JK |
827 | sdio->cur_page = NULL; |
828 | } | |
1da177e4 LT |
829 | return ret; |
830 | } | |
831 | ||
1da177e4 LT |
832 | /* |
833 | * If we are not writing the entire block and get_block() allocated | |
834 | * the block for us, we need to fill-in the unused portion of the | |
835 | * block with zeros. This happens only if user-buffer, fileoffset or | |
836 | * io length is not filesystem block-size multiple. | |
837 | * | |
838 | * `end' is zero if we're doing the start of the IO, 1 at the end of the | |
839 | * IO. | |
840 | */ | |
ba253fbf AK |
841 | static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio, |
842 | int end, struct buffer_head *map_bh) | |
1da177e4 LT |
843 | { |
844 | unsigned dio_blocks_per_fs_block; | |
845 | unsigned this_chunk_blocks; /* In dio_blocks */ | |
846 | unsigned this_chunk_bytes; | |
847 | struct page *page; | |
848 | ||
eb28be2b | 849 | sdio->start_zero_done = 1; |
18772641 | 850 | if (!sdio->blkfactor || !buffer_new(map_bh)) |
1da177e4 LT |
851 | return; |
852 | ||
eb28be2b AK |
853 | dio_blocks_per_fs_block = 1 << sdio->blkfactor; |
854 | this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1); | |
1da177e4 LT |
855 | |
856 | if (!this_chunk_blocks) | |
857 | return; | |
858 | ||
859 | /* | |
860 | * We need to zero out part of an fs block. It is either at the | |
861 | * beginning or the end of the fs block. | |
862 | */ | |
863 | if (end) | |
864 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; | |
865 | ||
eb28be2b | 866 | this_chunk_bytes = this_chunk_blocks << sdio->blkbits; |
1da177e4 | 867 | |
557ed1fa | 868 | page = ZERO_PAGE(0); |
eb28be2b | 869 | if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes, |
18772641 | 870 | sdio->next_block_for_io, map_bh)) |
1da177e4 LT |
871 | return; |
872 | ||
eb28be2b | 873 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 LT |
874 | } |
875 | ||
876 | /* | |
877 | * Walk the user pages, and the file, mapping blocks to disk and generating | |
878 | * a sequence of (page,offset,len,block) mappings. These mappings are injected | |
879 | * into submit_page_section(), which takes care of the next stage of submission | |
880 | * | |
881 | * Direct IO against a blockdev is different from a file. Because we can | |
882 | * happily perform page-sized but 512-byte aligned IOs. It is important that | |
883 | * blockdev IO be able to have fine alignment and large sizes. | |
884 | * | |
1d8fa7a2 | 885 | * So what we do is to permit the ->get_block function to populate bh.b_size |
1da177e4 LT |
886 | * with the size of IO which is permitted at this offset and this i_blkbits. |
887 | * | |
888 | * For best results, the blockdev should be set up with 512-byte i_blkbits and | |
1d8fa7a2 | 889 | * it should set b_size to PAGE_SIZE or more inside get_block(). This gives |
1da177e4 LT |
890 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
891 | */ | |
18772641 AK |
892 | static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, |
893 | struct buffer_head *map_bh) | |
1da177e4 | 894 | { |
c6293eac | 895 | const enum req_op dio_op = dio->opf & REQ_OP_MASK; |
eb28be2b | 896 | const unsigned blkbits = sdio->blkbits; |
dd545b52 | 897 | const unsigned i_blkbits = blkbits + sdio->blkfactor; |
1da177e4 LT |
898 | int ret = 0; |
899 | ||
eb28be2b | 900 | while (sdio->block_in_file < sdio->final_block_in_request) { |
7b2c99d1 AV |
901 | struct page *page; |
902 | size_t from, to; | |
6fcc5420 BH |
903 | |
904 | page = dio_get_page(dio, sdio); | |
1da177e4 LT |
905 | if (IS_ERR(page)) { |
906 | ret = PTR_ERR(page); | |
907 | goto out; | |
908 | } | |
6fcc5420 BH |
909 | from = sdio->head ? 0 : sdio->from; |
910 | to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE; | |
911 | sdio->head++; | |
1da177e4 | 912 | |
7b2c99d1 | 913 | while (from < to) { |
1da177e4 LT |
914 | unsigned this_chunk_bytes; /* # of bytes mapped */ |
915 | unsigned this_chunk_blocks; /* # of blocks */ | |
916 | unsigned u; | |
917 | ||
eb28be2b | 918 | if (sdio->blocks_available == 0) { |
1da177e4 LT |
919 | /* |
920 | * Need to go and map some more disk | |
921 | */ | |
922 | unsigned long blkmask; | |
923 | unsigned long dio_remainder; | |
924 | ||
18772641 | 925 | ret = get_more_blocks(dio, sdio, map_bh); |
1da177e4 | 926 | if (ret) { |
09cbfeaf | 927 | put_page(page); |
1da177e4 LT |
928 | goto out; |
929 | } | |
930 | if (!buffer_mapped(map_bh)) | |
931 | goto do_holes; | |
932 | ||
eb28be2b | 933 | sdio->blocks_available = |
f734c89c | 934 | map_bh->b_size >> blkbits; |
eb28be2b AK |
935 | sdio->next_block_for_io = |
936 | map_bh->b_blocknr << sdio->blkfactor; | |
f734c89c JK |
937 | if (buffer_new(map_bh)) { |
938 | clean_bdev_aliases( | |
939 | map_bh->b_bdev, | |
940 | map_bh->b_blocknr, | |
dd545b52 | 941 | map_bh->b_size >> i_blkbits); |
f734c89c | 942 | } |
1da177e4 | 943 | |
eb28be2b | 944 | if (!sdio->blkfactor) |
1da177e4 LT |
945 | goto do_holes; |
946 | ||
eb28be2b AK |
947 | blkmask = (1 << sdio->blkfactor) - 1; |
948 | dio_remainder = (sdio->block_in_file & blkmask); | |
1da177e4 LT |
949 | |
950 | /* | |
951 | * If we are at the start of IO and that IO | |
952 | * starts partway into a fs-block, | |
953 | * dio_remainder will be non-zero. If the IO | |
954 | * is a read then we can simply advance the IO | |
955 | * cursor to the first block which is to be | |
956 | * read. But if the IO is a write and the | |
957 | * block was newly allocated we cannot do that; | |
958 | * the start of the fs block must be zeroed out | |
959 | * on-disk | |
960 | */ | |
961 | if (!buffer_new(map_bh)) | |
eb28be2b AK |
962 | sdio->next_block_for_io += dio_remainder; |
963 | sdio->blocks_available -= dio_remainder; | |
1da177e4 LT |
964 | } |
965 | do_holes: | |
966 | /* Handle holes */ | |
967 | if (!buffer_mapped(map_bh)) { | |
35dc8161 | 968 | loff_t i_size_aligned; |
1da177e4 LT |
969 | |
970 | /* AKPM: eargh, -ENOTBLK is a hack */ | |
c6293eac | 971 | if (dio_op == REQ_OP_WRITE) { |
09cbfeaf | 972 | put_page(page); |
1da177e4 LT |
973 | return -ENOTBLK; |
974 | } | |
975 | ||
35dc8161 JM |
976 | /* |
977 | * Be sure to account for a partial block as the | |
978 | * last block in the file | |
979 | */ | |
980 | i_size_aligned = ALIGN(i_size_read(dio->inode), | |
981 | 1 << blkbits); | |
eb28be2b | 982 | if (sdio->block_in_file >= |
35dc8161 | 983 | i_size_aligned >> blkbits) { |
1da177e4 | 984 | /* We hit eof */ |
09cbfeaf | 985 | put_page(page); |
1da177e4 LT |
986 | goto out; |
987 | } | |
7b2c99d1 | 988 | zero_user(page, from, 1 << blkbits); |
eb28be2b | 989 | sdio->block_in_file++; |
7b2c99d1 | 990 | from += 1 << blkbits; |
3320c60b | 991 | dio->result += 1 << blkbits; |
1da177e4 LT |
992 | goto next_block; |
993 | } | |
994 | ||
995 | /* | |
996 | * If we're performing IO which has an alignment which | |
997 | * is finer than the underlying fs, go check to see if | |
998 | * we must zero out the start of this block. | |
999 | */ | |
eb28be2b | 1000 | if (unlikely(sdio->blkfactor && !sdio->start_zero_done)) |
18772641 | 1001 | dio_zero_block(dio, sdio, 0, map_bh); |
1da177e4 LT |
1002 | |
1003 | /* | |
1004 | * Work out, in this_chunk_blocks, how much disk we | |
1005 | * can add to this page | |
1006 | */ | |
eb28be2b | 1007 | this_chunk_blocks = sdio->blocks_available; |
7b2c99d1 | 1008 | u = (to - from) >> blkbits; |
1da177e4 LT |
1009 | if (this_chunk_blocks > u) |
1010 | this_chunk_blocks = u; | |
eb28be2b | 1011 | u = sdio->final_block_in_request - sdio->block_in_file; |
1da177e4 LT |
1012 | if (this_chunk_blocks > u) |
1013 | this_chunk_blocks = u; | |
1014 | this_chunk_bytes = this_chunk_blocks << blkbits; | |
1015 | BUG_ON(this_chunk_bytes == 0); | |
1016 | ||
092c8d46 JK |
1017 | if (this_chunk_blocks == sdio->blocks_available) |
1018 | sdio->boundary = buffer_boundary(map_bh); | |
eb28be2b | 1019 | ret = submit_page_section(dio, sdio, page, |
7b2c99d1 | 1020 | from, |
eb28be2b | 1021 | this_chunk_bytes, |
18772641 AK |
1022 | sdio->next_block_for_io, |
1023 | map_bh); | |
1da177e4 | 1024 | if (ret) { |
09cbfeaf | 1025 | put_page(page); |
1da177e4 LT |
1026 | goto out; |
1027 | } | |
eb28be2b | 1028 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 | 1029 | |
eb28be2b | 1030 | sdio->block_in_file += this_chunk_blocks; |
7b2c99d1 AV |
1031 | from += this_chunk_bytes; |
1032 | dio->result += this_chunk_bytes; | |
eb28be2b | 1033 | sdio->blocks_available -= this_chunk_blocks; |
1da177e4 | 1034 | next_block: |
eb28be2b AK |
1035 | BUG_ON(sdio->block_in_file > sdio->final_block_in_request); |
1036 | if (sdio->block_in_file == sdio->final_block_in_request) | |
1da177e4 LT |
1037 | break; |
1038 | } | |
1039 | ||
1040 | /* Drop the ref which was taken in get_user_pages() */ | |
09cbfeaf | 1041 | put_page(page); |
1da177e4 LT |
1042 | } |
1043 | out: | |
1044 | return ret; | |
1045 | } | |
1046 | ||
847cc637 | 1047 | static inline int drop_refcount(struct dio *dio) |
1da177e4 | 1048 | { |
847cc637 | 1049 | int ret2; |
5eb6c7a2 | 1050 | unsigned long flags; |
1da177e4 | 1051 | |
8459d86a ZB |
1052 | /* |
1053 | * Sync will always be dropping the final ref and completing the | |
5eb6c7a2 ZB |
1054 | * operation. AIO can if it was a broken operation described above or |
1055 | * in fact if all the bios race to complete before we get here. In | |
1056 | * that case dio_complete() translates the EIOCBQUEUED into the proper | |
04b2fa9f | 1057 | * return code that the caller will hand to ->complete(). |
5eb6c7a2 ZB |
1058 | * |
1059 | * This is managed by the bio_lock instead of being an atomic_t so that | |
1060 | * completion paths can drop their ref and use the remaining count to | |
1061 | * decide to wake the submission path atomically. | |
8459d86a | 1062 | */ |
5eb6c7a2 ZB |
1063 | spin_lock_irqsave(&dio->bio_lock, flags); |
1064 | ret2 = --dio->refcount; | |
1065 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
847cc637 | 1066 | return ret2; |
1da177e4 LT |
1067 | } |
1068 | ||
eafdc7d1 CH |
1069 | /* |
1070 | * This is a library function for use by filesystem drivers. | |
1071 | * | |
1072 | * The locking rules are governed by the flags parameter: | |
1073 | * - if the flags value contains DIO_LOCKING we use a fancy locking | |
1074 | * scheme for dumb filesystems. | |
1075 | * For writes this function is called under i_mutex and returns with | |
1076 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | |
1077 | * taken and dropped again before returning. | |
eafdc7d1 CH |
1078 | * - if the flags value does NOT contain DIO_LOCKING we don't use any |
1079 | * internal locking but rather rely on the filesystem to synchronize | |
1080 | * direct I/O reads/writes versus each other and truncate. | |
df2d6f26 CH |
1081 | * |
1082 | * To help with locking against truncate we incremented the i_dio_count | |
1083 | * counter before starting direct I/O, and decrement it once we are done. | |
1084 | * Truncate can wait for it to reach zero to provide exclusion. It is | |
1085 | * expected that filesystem provide exclusion between new direct I/O | |
1086 | * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, | |
1087 | * but other filesystems need to take care of this on their own. | |
ba253fbf AK |
1088 | * |
1089 | * NOTE: if you pass "sdio" to anything by pointer make sure that function | |
1090 | * is always inlined. Otherwise gcc is unable to split the structure into | |
1091 | * individual fields and will generate much worse code. This is important | |
1092 | * for the whole file. | |
eafdc7d1 | 1093 | */ |
c22198e7 CH |
1094 | ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, |
1095 | struct block_device *bdev, struct iov_iter *iter, | |
1096 | get_block_t get_block, dio_iodone_t end_io, | |
0aaf08de | 1097 | int flags) |
1da177e4 | 1098 | { |
6aa7de05 | 1099 | unsigned i_blkbits = READ_ONCE(inode->i_blkbits); |
ab73857e | 1100 | unsigned blkbits = i_blkbits; |
1da177e4 LT |
1101 | unsigned blocksize_mask = (1 << blkbits) - 1; |
1102 | ssize_t retval = -EINVAL; | |
1c0ff0f1 | 1103 | const size_t count = iov_iter_count(iter); |
c8b8e32d | 1104 | loff_t offset = iocb->ki_pos; |
1c0ff0f1 | 1105 | const loff_t end = offset + count; |
1da177e4 | 1106 | struct dio *dio; |
eb28be2b | 1107 | struct dio_submit sdio = { 0, }; |
847cc637 | 1108 | struct buffer_head map_bh = { 0, }; |
647d1e4c | 1109 | struct blk_plug plug; |
886a3911 | 1110 | unsigned long align = offset | iov_iter_alignment(iter); |
1da177e4 | 1111 | |
65dd2aa9 AK |
1112 | /* |
1113 | * Avoid references to bdev if not absolutely needed to give | |
1114 | * the early prefetch in the caller enough time. | |
1115 | */ | |
1da177e4 | 1116 | |
f9b5570d | 1117 | /* watch out for a 0 len io from a tricksy fs */ |
1c0ff0f1 | 1118 | if (iov_iter_rw(iter) == READ && !count) |
f9b5570d CH |
1119 | return 0; |
1120 | ||
6e8267f5 | 1121 | dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); |
1da177e4 | 1122 | if (!dio) |
46d71602 | 1123 | return -ENOMEM; |
23aee091 JM |
1124 | /* |
1125 | * Believe it or not, zeroing out the page array caused a .5% | |
1126 | * performance regression in a database benchmark. So, we take | |
1127 | * care to only zero out what's needed. | |
1128 | */ | |
1129 | memset(dio, 0, offsetof(struct dio, pages)); | |
1da177e4 | 1130 | |
5fe878ae | 1131 | dio->flags = flags; |
0a9164cb GKB |
1132 | if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) { |
1133 | /* will be released by direct_io_worker */ | |
1134 | inode_lock(inode); | |
1da177e4 LT |
1135 | } |
1136 | ||
74cedf9b JK |
1137 | /* Once we sampled i_size check for reads beyond EOF */ |
1138 | dio->i_size = i_size_read(inode); | |
1139 | if (iov_iter_rw(iter) == READ && offset >= dio->i_size) { | |
2d4594ac | 1140 | retval = 0; |
46d71602 | 1141 | goto fail_dio; |
74cedf9b JK |
1142 | } |
1143 | ||
41b21af3 GKB |
1144 | if (align & blocksize_mask) { |
1145 | if (bdev) | |
1146 | blkbits = blksize_bits(bdev_logical_block_size(bdev)); | |
1147 | blocksize_mask = (1 << blkbits) - 1; | |
1148 | if (align & blocksize_mask) | |
1149 | goto fail_dio; | |
1150 | } | |
1151 | ||
0a9164cb GKB |
1152 | if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) { |
1153 | struct address_space *mapping = iocb->ki_filp->f_mapping; | |
1154 | ||
1155 | retval = filemap_write_and_wait_range(mapping, offset, end - 1); | |
1156 | if (retval) | |
1157 | goto fail_dio; | |
74cedf9b JK |
1158 | } |
1159 | ||
1da177e4 | 1160 | /* |
60392573 CH |
1161 | * For file extending writes updating i_size before data writeouts |
1162 | * complete can expose uninitialized blocks in dumb filesystems. | |
1163 | * In that case we need to wait for I/O completion even if asked | |
1164 | * for an asynchronous write. | |
1da177e4 | 1165 | */ |
60392573 CH |
1166 | if (is_sync_kiocb(iocb)) |
1167 | dio->is_async = false; | |
c8f4c36f | 1168 | else if (iov_iter_rw(iter) == WRITE && end > i_size_read(inode)) |
60392573 CH |
1169 | dio->is_async = false; |
1170 | else | |
1171 | dio->is_async = true; | |
1172 | ||
847cc637 | 1173 | dio->inode = inode; |
8a4c1e42 | 1174 | if (iov_iter_rw(iter) == WRITE) { |
c6293eac | 1175 | dio->opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE; |
03a07c92 | 1176 | if (iocb->ki_flags & IOCB_NOWAIT) |
c6293eac | 1177 | dio->opf |= REQ_NOWAIT; |
8a4c1e42 | 1178 | } else { |
c6293eac | 1179 | dio->opf = REQ_OP_READ; |
8a4c1e42 | 1180 | } |
02afc27f CH |
1181 | |
1182 | /* | |
1183 | * For AIO O_(D)SYNC writes we need to defer completions to a workqueue | |
1184 | * so that we can call ->fsync. | |
1185 | */ | |
332391a9 LC |
1186 | if (dio->is_async && iov_iter_rw(iter) == WRITE) { |
1187 | retval = 0; | |
91b94c5d | 1188 | if (iocb_is_dsync(iocb)) |
332391a9 LC |
1189 | retval = dio_set_defer_completion(dio); |
1190 | else if (!dio->inode->i_sb->s_dio_done_wq) { | |
1191 | /* | |
1192 | * In case of AIO write racing with buffered read we | |
1193 | * need to defer completion. We can't decide this now, | |
1194 | * however the workqueue needs to be initialized here. | |
1195 | */ | |
1196 | retval = sb_init_dio_done_wq(dio->inode->i_sb); | |
1197 | } | |
46d71602 GKB |
1198 | if (retval) |
1199 | goto fail_dio; | |
02afc27f CH |
1200 | } |
1201 | ||
1202 | /* | |
1203 | * Will be decremented at I/O completion time. | |
1204 | */ | |
ce3077ee | 1205 | inode_dio_begin(inode); |
02afc27f CH |
1206 | |
1207 | retval = 0; | |
847cc637 | 1208 | sdio.blkbits = blkbits; |
ab73857e | 1209 | sdio.blkfactor = i_blkbits - blkbits; |
847cc637 AK |
1210 | sdio.block_in_file = offset >> blkbits; |
1211 | ||
1212 | sdio.get_block = get_block; | |
1213 | dio->end_io = end_io; | |
847cc637 AK |
1214 | sdio.final_block_in_bio = -1; |
1215 | sdio.next_block_for_io = -1; | |
1216 | ||
1217 | dio->iocb = iocb; | |
847cc637 AK |
1218 | |
1219 | spin_lock_init(&dio->bio_lock); | |
1220 | dio->refcount = 1; | |
1221 | ||
fcb14cb1 | 1222 | dio->should_dirty = user_backed_iter(iter) && iov_iter_rw(iter) == READ; |
7b2c99d1 | 1223 | sdio.iter = iter; |
1c0ff0f1 | 1224 | sdio.final_block_in_request = end >> blkbits; |
7b2c99d1 | 1225 | |
847cc637 AK |
1226 | /* |
1227 | * In case of non-aligned buffers, we may need 2 more | |
1228 | * pages since we need to zero out first and last block. | |
1229 | */ | |
1230 | if (unlikely(sdio.blkfactor)) | |
1231 | sdio.pages_in_io = 2; | |
1232 | ||
f67da30c | 1233 | sdio.pages_in_io += iov_iter_npages(iter, INT_MAX); |
847cc637 | 1234 | |
647d1e4c FW |
1235 | blk_start_plug(&plug); |
1236 | ||
7b2c99d1 AV |
1237 | retval = do_direct_IO(dio, &sdio, &map_bh); |
1238 | if (retval) | |
1239 | dio_cleanup(dio, &sdio); | |
847cc637 AK |
1240 | |
1241 | if (retval == -ENOTBLK) { | |
1242 | /* | |
1243 | * The remaining part of the request will be | |
3d742d4b | 1244 | * handled by buffered I/O when we return |
847cc637 AK |
1245 | */ |
1246 | retval = 0; | |
1247 | } | |
1248 | /* | |
1249 | * There may be some unwritten disk at the end of a part-written | |
1250 | * fs-block-sized block. Go zero that now. | |
1251 | */ | |
1252 | dio_zero_block(dio, &sdio, 1, &map_bh); | |
1253 | ||
1254 | if (sdio.cur_page) { | |
1255 | ssize_t ret2; | |
1256 | ||
1257 | ret2 = dio_send_cur_page(dio, &sdio, &map_bh); | |
1258 | if (retval == 0) | |
1259 | retval = ret2; | |
09cbfeaf | 1260 | put_page(sdio.cur_page); |
847cc637 AK |
1261 | sdio.cur_page = NULL; |
1262 | } | |
1263 | if (sdio.bio) | |
1264 | dio_bio_submit(dio, &sdio); | |
1265 | ||
647d1e4c FW |
1266 | blk_finish_plug(&plug); |
1267 | ||
847cc637 AK |
1268 | /* |
1269 | * It is possible that, we return short IO due to end of file. | |
1270 | * In that case, we need to release all the pages we got hold on. | |
1271 | */ | |
1272 | dio_cleanup(dio, &sdio); | |
1273 | ||
1274 | /* | |
1275 | * All block lookups have been performed. For READ requests | |
1276 | * we can let i_mutex go now that its achieved its purpose | |
1277 | * of protecting us from looking up uninitialized blocks. | |
1278 | */ | |
17f8c842 | 1279 | if (iov_iter_rw(iter) == READ && (dio->flags & DIO_LOCKING)) |
5955102c | 1280 | inode_unlock(dio->inode); |
847cc637 AK |
1281 | |
1282 | /* | |
1283 | * The only time we want to leave bios in flight is when a successful | |
1284 | * partial aio read or full aio write have been setup. In that case | |
1285 | * bio completion will call aio_complete. The only time it's safe to | |
1286 | * call aio_complete is when we return -EIOCBQUEUED, so we key on that. | |
1287 | * This had *better* be the only place that raises -EIOCBQUEUED. | |
1288 | */ | |
1289 | BUG_ON(retval == -EIOCBQUEUED); | |
1290 | if (dio->is_async && retval == 0 && dio->result && | |
17f8c842 | 1291 | (iov_iter_rw(iter) == READ || dio->result == count)) |
847cc637 | 1292 | retval = -EIOCBQUEUED; |
af436472 | 1293 | else |
847cc637 AK |
1294 | dio_await_completion(dio); |
1295 | ||
1296 | if (drop_refcount(dio) == 0) { | |
ffe51f01 | 1297 | retval = dio_complete(dio, retval, DIO_COMPLETE_INVALIDATE); |
847cc637 AK |
1298 | } else |
1299 | BUG_ON(retval != -EIOCBQUEUED); | |
1da177e4 | 1300 | |
46d71602 GKB |
1301 | return retval; |
1302 | ||
1303 | fail_dio: | |
1304 | if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) | |
1305 | inode_unlock(inode); | |
1306 | ||
1307 | kmem_cache_free(dio_cache, dio); | |
7bb46a67 | 1308 | return retval; |
1309 | } | |
1da177e4 | 1310 | EXPORT_SYMBOL(__blockdev_direct_IO); |
6e8267f5 AK |
1311 | |
1312 | static __init int dio_init(void) | |
1313 | { | |
1314 | dio_cache = KMEM_CACHE(dio, SLAB_PANIC); | |
1315 | return 0; | |
1316 | } | |
1317 | module_init(dio_init) |