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1da177e4 LT |
1 | /* |
2 | * fs/direct-io.c | |
3 | * | |
4 | * Copyright (C) 2002, Linus Torvalds. | |
5 | * | |
6 | * O_DIRECT | |
7 | * | |
e1f8e874 | 8 | * 04Jul2002 Andrew Morton |
1da177e4 LT |
9 | * Initial version |
10 | * 11Sep2002 janetinc@us.ibm.com | |
11 | * added readv/writev support. | |
e1f8e874 | 12 | * 29Oct2002 Andrew Morton |
1da177e4 LT |
13 | * rewrote bio_add_page() support. |
14 | * 30Oct2002 pbadari@us.ibm.com | |
15 | * added support for non-aligned IO. | |
16 | * 06Nov2002 pbadari@us.ibm.com | |
17 | * added asynchronous IO support. | |
18 | * 21Jul2003 nathans@sgi.com | |
19 | * added IO completion notifier. | |
20 | */ | |
21 | ||
22 | #include <linux/kernel.h> | |
23 | #include <linux/module.h> | |
24 | #include <linux/types.h> | |
25 | #include <linux/fs.h> | |
26 | #include <linux/mm.h> | |
27 | #include <linux/slab.h> | |
28 | #include <linux/highmem.h> | |
29 | #include <linux/pagemap.h> | |
98c4d57d | 30 | #include <linux/task_io_accounting_ops.h> |
1da177e4 LT |
31 | #include <linux/bio.h> |
32 | #include <linux/wait.h> | |
33 | #include <linux/err.h> | |
34 | #include <linux/blkdev.h> | |
35 | #include <linux/buffer_head.h> | |
36 | #include <linux/rwsem.h> | |
37 | #include <linux/uio.h> | |
60063497 | 38 | #include <linux/atomic.h> |
65dd2aa9 | 39 | #include <linux/prefetch.h> |
1da177e4 LT |
40 | |
41 | /* | |
42 | * How many user pages to map in one call to get_user_pages(). This determines | |
cde1ecb3 | 43 | * the size of a structure in the slab cache |
1da177e4 LT |
44 | */ |
45 | #define DIO_PAGES 64 | |
46 | ||
ffe51f01 LC |
47 | /* |
48 | * Flags for dio_complete() | |
49 | */ | |
50 | #define DIO_COMPLETE_ASYNC 0x01 /* This is async IO */ | |
51 | #define DIO_COMPLETE_INVALIDATE 0x02 /* Can invalidate pages */ | |
52 | ||
1da177e4 LT |
53 | /* |
54 | * This code generally works in units of "dio_blocks". A dio_block is | |
55 | * somewhere between the hard sector size and the filesystem block size. it | |
56 | * is determined on a per-invocation basis. When talking to the filesystem | |
57 | * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity | |
58 | * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted | |
59 | * to bio_block quantities by shifting left by blkfactor. | |
60 | * | |
61 | * If blkfactor is zero then the user's request was aligned to the filesystem's | |
62 | * blocksize. | |
1da177e4 LT |
63 | */ |
64 | ||
eb28be2b AK |
65 | /* dio_state only used in the submission path */ |
66 | ||
67 | struct dio_submit { | |
1da177e4 | 68 | struct bio *bio; /* bio under assembly */ |
1da177e4 LT |
69 | unsigned blkbits; /* doesn't change */ |
70 | unsigned blkfactor; /* When we're using an alignment which | |
71 | is finer than the filesystem's soft | |
72 | blocksize, this specifies how much | |
73 | finer. blkfactor=2 means 1/4-block | |
74 | alignment. Does not change */ | |
75 | unsigned start_zero_done; /* flag: sub-blocksize zeroing has | |
76 | been performed at the start of a | |
77 | write */ | |
78 | int pages_in_io; /* approximate total IO pages */ | |
1da177e4 LT |
79 | sector_t block_in_file; /* Current offset into the underlying |
80 | file in dio_block units. */ | |
81 | unsigned blocks_available; /* At block_in_file. changes */ | |
0dc2bc49 | 82 | int reap_counter; /* rate limit reaping */ |
1da177e4 | 83 | sector_t final_block_in_request;/* doesn't change */ |
1da177e4 | 84 | int boundary; /* prev block is at a boundary */ |
1d8fa7a2 | 85 | get_block_t *get_block; /* block mapping function */ |
facd07b0 | 86 | dio_submit_t *submit_io; /* IO submition function */ |
eb28be2b | 87 | |
facd07b0 | 88 | loff_t logical_offset_in_bio; /* current first logical block in bio */ |
1da177e4 LT |
89 | sector_t final_block_in_bio; /* current final block in bio + 1 */ |
90 | sector_t next_block_for_io; /* next block to be put under IO, | |
91 | in dio_blocks units */ | |
1da177e4 LT |
92 | |
93 | /* | |
94 | * Deferred addition of a page to the dio. These variables are | |
95 | * private to dio_send_cur_page(), submit_page_section() and | |
96 | * dio_bio_add_page(). | |
97 | */ | |
98 | struct page *cur_page; /* The page */ | |
99 | unsigned cur_page_offset; /* Offset into it, in bytes */ | |
100 | unsigned cur_page_len; /* Nr of bytes at cur_page_offset */ | |
101 | sector_t cur_page_block; /* Where it starts */ | |
facd07b0 | 102 | loff_t cur_page_fs_offset; /* Offset in file */ |
1da177e4 | 103 | |
7b2c99d1 | 104 | struct iov_iter *iter; |
1da177e4 LT |
105 | /* |
106 | * Page queue. These variables belong to dio_refill_pages() and | |
107 | * dio_get_page(). | |
108 | */ | |
1da177e4 LT |
109 | unsigned head; /* next page to process */ |
110 | unsigned tail; /* last valid page + 1 */ | |
7b2c99d1 | 111 | size_t from, to; |
eb28be2b AK |
112 | }; |
113 | ||
114 | /* dio_state communicated between submission path and end_io */ | |
115 | struct dio { | |
116 | int flags; /* doesn't change */ | |
8a4c1e42 MC |
117 | int op; |
118 | int op_flags; | |
15c4f638 | 119 | blk_qc_t bio_cookie; |
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 | { |
7b2c99d1 | 168 | ssize_t ret; |
1da177e4 | 169 | |
2c80929c | 170 | ret = iov_iter_get_pages(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES, |
7b2c99d1 | 171 | &sdio->from); |
1da177e4 | 172 | |
8a4c1e42 | 173 | if (ret < 0 && sdio->blocks_available && (dio->op == REQ_OP_WRITE)) { |
557ed1fa | 174 | struct page *page = ZERO_PAGE(0); |
1da177e4 LT |
175 | /* |
176 | * A memory fault, but the filesystem has some outstanding | |
177 | * mapped blocks. We need to use those blocks up to avoid | |
178 | * leaking stale data in the file. | |
179 | */ | |
180 | if (dio->page_errors == 0) | |
181 | dio->page_errors = ret; | |
09cbfeaf | 182 | get_page(page); |
b5810039 | 183 | dio->pages[0] = page; |
eb28be2b AK |
184 | sdio->head = 0; |
185 | sdio->tail = 1; | |
7b2c99d1 AV |
186 | sdio->from = 0; |
187 | sdio->to = PAGE_SIZE; | |
188 | return 0; | |
1da177e4 LT |
189 | } |
190 | ||
191 | if (ret >= 0) { | |
7b2c99d1 AV |
192 | iov_iter_advance(sdio->iter, ret); |
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 | ||
5a9d929d DW |
222 | /* |
223 | * Warn about a page cache invalidation failure during a direct io write. | |
224 | */ | |
225 | void dio_warn_stale_pagecache(struct file *filp) | |
226 | { | |
227 | static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST); | |
228 | char pathname[128]; | |
229 | struct inode *inode = file_inode(filp); | |
230 | char *path; | |
231 | ||
232 | errseq_set(&inode->i_mapping->wb_err, -EIO); | |
233 | if (__ratelimit(&_rs)) { | |
234 | path = file_path(filp, pathname, sizeof(pathname)); | |
235 | if (IS_ERR(path)) | |
236 | path = "(unknown)"; | |
237 | pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n"); | |
238 | pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid, | |
239 | current->comm); | |
240 | } | |
241 | } | |
242 | ||
6d544bb4 ZB |
243 | /** |
244 | * dio_complete() - called when all DIO BIO I/O has been completed | |
245 | * @offset: the byte offset in the file of the completed operation | |
246 | * | |
7b7a8665 CH |
247 | * This drops i_dio_count, lets interested parties know that a DIO operation |
248 | * has completed, and calculates the resulting return code for the operation. | |
6d544bb4 ZB |
249 | * |
250 | * It lets the filesystem know if it registered an interest earlier via | |
251 | * get_block. Pass the private field of the map buffer_head so that | |
252 | * filesystems can use it to hold additional state between get_block calls and | |
253 | * dio_complete. | |
1da177e4 | 254 | */ |
ffe51f01 | 255 | static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags) |
1da177e4 | 256 | { |
716b9bc0 | 257 | loff_t offset = dio->iocb->ki_pos; |
6d544bb4 | 258 | ssize_t transferred = 0; |
332391a9 | 259 | int err; |
6d544bb4 | 260 | |
8459d86a ZB |
261 | /* |
262 | * AIO submission can race with bio completion to get here while | |
263 | * expecting to have the last io completed by bio completion. | |
264 | * In that case -EIOCBQUEUED is in fact not an error we want | |
265 | * to preserve through this call. | |
266 | */ | |
267 | if (ret == -EIOCBQUEUED) | |
268 | ret = 0; | |
269 | ||
6d544bb4 ZB |
270 | if (dio->result) { |
271 | transferred = dio->result; | |
272 | ||
273 | /* Check for short read case */ | |
8a4c1e42 MC |
274 | if ((dio->op == REQ_OP_READ) && |
275 | ((offset + transferred) > dio->i_size)) | |
6d544bb4 | 276 | transferred = dio->i_size - offset; |
4038acdb AV |
277 | /* ignore EFAULT if some IO has been done */ |
278 | if (unlikely(ret == -EFAULT) && transferred) | |
279 | ret = 0; | |
6d544bb4 ZB |
280 | } |
281 | ||
6d544bb4 ZB |
282 | if (ret == 0) |
283 | ret = dio->page_errors; | |
284 | if (ret == 0) | |
285 | ret = dio->io_error; | |
286 | if (ret == 0) | |
287 | ret = transferred; | |
288 | ||
5e25c269 EG |
289 | if (dio->end_io) { |
290 | // XXX: ki_pos?? | |
291 | err = dio->end_io(dio->iocb, offset, ret, dio->private); | |
292 | if (err) | |
293 | ret = err; | |
294 | } | |
295 | ||
332391a9 LC |
296 | /* |
297 | * Try again to invalidate clean pages which might have been cached by | |
298 | * non-direct readahead, or faulted in by get_user_pages() if the source | |
299 | * of the write was an mmap'ed region of the file we're writing. Either | |
300 | * one is a pretty crazy thing to do, so we don't support it 100%. If | |
301 | * this invalidation fails, tough, the write still worked... | |
5e25c269 EG |
302 | * |
303 | * And this page cache invalidation has to be after dio->end_io(), as | |
304 | * some filesystems convert unwritten extents to real allocations in | |
305 | * end_io() when necessary, otherwise a racing buffer read would cache | |
306 | * zeros from unwritten extents. | |
332391a9 | 307 | */ |
ffe51f01 LC |
308 | if (flags & DIO_COMPLETE_INVALIDATE && |
309 | ret > 0 && dio->op == REQ_OP_WRITE && | |
332391a9 LC |
310 | dio->inode->i_mapping->nrpages) { |
311 | err = invalidate_inode_pages2_range(dio->inode->i_mapping, | |
312 | offset >> PAGE_SHIFT, | |
313 | (offset + ret - 1) >> PAGE_SHIFT); | |
5a9d929d DW |
314 | if (err) |
315 | dio_warn_stale_pagecache(dio->iocb->ki_filp); | |
332391a9 LC |
316 | } |
317 | ||
ce3077ee | 318 | inode_dio_end(dio->inode); |
fe0f07d0 | 319 | |
ffe51f01 | 320 | if (flags & DIO_COMPLETE_ASYNC) { |
e2592217 CH |
321 | /* |
322 | * generic_write_sync expects ki_pos to have been updated | |
323 | * already, but the submission path only does this for | |
324 | * synchronous I/O. | |
325 | */ | |
326 | dio->iocb->ki_pos += transferred; | |
02afc27f | 327 | |
8a4c1e42 | 328 | if (dio->op == REQ_OP_WRITE) |
e2592217 | 329 | ret = generic_write_sync(dio->iocb, transferred); |
04b2fa9f | 330 | dio->iocb->ki_complete(dio->iocb, ret, 0); |
02afc27f | 331 | } |
40e2e973 | 332 | |
7b7a8665 | 333 | kmem_cache_free(dio_cache, dio); |
6d544bb4 | 334 | return ret; |
1da177e4 LT |
335 | } |
336 | ||
7b7a8665 CH |
337 | static void dio_aio_complete_work(struct work_struct *work) |
338 | { | |
339 | struct dio *dio = container_of(work, struct dio, complete_work); | |
340 | ||
ffe51f01 | 341 | dio_complete(dio, 0, DIO_COMPLETE_ASYNC | DIO_COMPLETE_INVALIDATE); |
7b7a8665 CH |
342 | } |
343 | ||
4e4cbee9 | 344 | static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio); |
7b7a8665 | 345 | |
1da177e4 LT |
346 | /* |
347 | * Asynchronous IO callback. | |
348 | */ | |
4246a0b6 | 349 | static void dio_bio_end_aio(struct bio *bio) |
1da177e4 LT |
350 | { |
351 | struct dio *dio = bio->bi_private; | |
5eb6c7a2 ZB |
352 | unsigned long remaining; |
353 | unsigned long flags; | |
332391a9 | 354 | bool defer_completion = false; |
1da177e4 | 355 | |
1da177e4 LT |
356 | /* cleanup the bio */ |
357 | dio_bio_complete(dio, bio); | |
0273201e | 358 | |
5eb6c7a2 ZB |
359 | spin_lock_irqsave(&dio->bio_lock, flags); |
360 | remaining = --dio->refcount; | |
361 | if (remaining == 1 && dio->waiter) | |
20258b2b | 362 | wake_up_process(dio->waiter); |
5eb6c7a2 | 363 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
20258b2b | 364 | |
8459d86a | 365 | if (remaining == 0) { |
332391a9 LC |
366 | /* |
367 | * Defer completion when defer_completion is set or | |
368 | * when the inode has pages mapped and this is AIO write. | |
369 | * We need to invalidate those pages because there is a | |
370 | * chance they contain stale data in the case buffered IO | |
371 | * went in between AIO submission and completion into the | |
372 | * same region. | |
373 | */ | |
374 | if (dio->result) | |
375 | defer_completion = dio->defer_completion || | |
376 | (dio->op == REQ_OP_WRITE && | |
377 | dio->inode->i_mapping->nrpages); | |
378 | if (defer_completion) { | |
7b7a8665 CH |
379 | INIT_WORK(&dio->complete_work, dio_aio_complete_work); |
380 | queue_work(dio->inode->i_sb->s_dio_done_wq, | |
381 | &dio->complete_work); | |
382 | } else { | |
ffe51f01 | 383 | dio_complete(dio, 0, DIO_COMPLETE_ASYNC); |
7b7a8665 | 384 | } |
8459d86a | 385 | } |
1da177e4 LT |
386 | } |
387 | ||
388 | /* | |
389 | * The BIO completion handler simply queues the BIO up for the process-context | |
390 | * handler. | |
391 | * | |
392 | * During I/O bi_private points at the dio. After I/O, bi_private is used to | |
393 | * implement a singly-linked list of completed BIOs, at dio->bio_list. | |
394 | */ | |
4246a0b6 | 395 | static void dio_bio_end_io(struct bio *bio) |
1da177e4 LT |
396 | { |
397 | struct dio *dio = bio->bi_private; | |
398 | unsigned long flags; | |
399 | ||
1da177e4 LT |
400 | spin_lock_irqsave(&dio->bio_lock, flags); |
401 | bio->bi_private = dio->bio_list; | |
402 | dio->bio_list = bio; | |
5eb6c7a2 | 403 | if (--dio->refcount == 1 && dio->waiter) |
1da177e4 LT |
404 | wake_up_process(dio->waiter); |
405 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
1da177e4 LT |
406 | } |
407 | ||
facd07b0 JB |
408 | /** |
409 | * dio_end_io - handle the end io action for the given bio | |
410 | * @bio: The direct io bio thats being completed | |
facd07b0 JB |
411 | * |
412 | * This is meant to be called by any filesystem that uses their own dio_submit_t | |
413 | * so that the DIO specific endio actions are dealt with after the filesystem | |
414 | * has done it's completion work. | |
415 | */ | |
4055351c | 416 | void dio_end_io(struct bio *bio) |
facd07b0 JB |
417 | { |
418 | struct dio *dio = bio->bi_private; | |
419 | ||
420 | if (dio->is_async) | |
4246a0b6 | 421 | dio_bio_end_aio(bio); |
facd07b0 | 422 | else |
4246a0b6 | 423 | dio_bio_end_io(bio); |
facd07b0 JB |
424 | } |
425 | EXPORT_SYMBOL_GPL(dio_end_io); | |
426 | ||
ba253fbf | 427 | static inline void |
eb28be2b AK |
428 | dio_bio_alloc(struct dio *dio, struct dio_submit *sdio, |
429 | struct block_device *bdev, | |
430 | sector_t first_sector, int nr_vecs) | |
1da177e4 LT |
431 | { |
432 | struct bio *bio; | |
433 | ||
20d9600c | 434 | /* |
0eb0b63c CH |
435 | * bio_alloc() is guaranteed to return a bio when allowed to sleep and |
436 | * we request a valid number of vectors. | |
20d9600c | 437 | */ |
1da177e4 | 438 | bio = bio_alloc(GFP_KERNEL, nr_vecs); |
1da177e4 | 439 | |
74d46992 | 440 | bio_set_dev(bio, bdev); |
4f024f37 | 441 | bio->bi_iter.bi_sector = first_sector; |
8a4c1e42 | 442 | bio_set_op_attrs(bio, dio->op, dio->op_flags); |
1da177e4 LT |
443 | if (dio->is_async) |
444 | bio->bi_end_io = dio_bio_end_aio; | |
445 | else | |
446 | bio->bi_end_io = dio_bio_end_io; | |
447 | ||
45d06cf7 JA |
448 | bio->bi_write_hint = dio->iocb->ki_hint; |
449 | ||
eb28be2b AK |
450 | sdio->bio = bio; |
451 | sdio->logical_offset_in_bio = sdio->cur_page_fs_offset; | |
1da177e4 LT |
452 | } |
453 | ||
454 | /* | |
455 | * In the AIO read case we speculatively dirty the pages before starting IO. | |
456 | * During IO completion, any of these pages which happen to have been written | |
457 | * back will be redirtied by bio_check_pages_dirty(). | |
0273201e ZB |
458 | * |
459 | * bios hold a dio reference between submit_bio and ->end_io. | |
1da177e4 | 460 | */ |
ba253fbf | 461 | static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 462 | { |
eb28be2b | 463 | struct bio *bio = sdio->bio; |
5eb6c7a2 | 464 | unsigned long flags; |
1da177e4 LT |
465 | |
466 | bio->bi_private = dio; | |
5eb6c7a2 ZB |
467 | |
468 | spin_lock_irqsave(&dio->bio_lock, flags); | |
469 | dio->refcount++; | |
470 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
471 | ||
8a4c1e42 | 472 | if (dio->is_async && dio->op == REQ_OP_READ && dio->should_dirty) |
1da177e4 | 473 | bio_set_pages_dirty(bio); |
5eb6c7a2 | 474 | |
74d46992 | 475 | dio->bio_disk = bio->bi_disk; |
c1c53460 | 476 | |
15c4f638 | 477 | if (sdio->submit_io) { |
8a4c1e42 | 478 | sdio->submit_io(bio, dio->inode, sdio->logical_offset_in_bio); |
15c4f638 | 479 | dio->bio_cookie = BLK_QC_T_NONE; |
c1c53460 | 480 | } else |
4e49ea4a | 481 | dio->bio_cookie = submit_bio(bio); |
1da177e4 | 482 | |
eb28be2b AK |
483 | sdio->bio = NULL; |
484 | sdio->boundary = 0; | |
485 | sdio->logical_offset_in_bio = 0; | |
1da177e4 LT |
486 | } |
487 | ||
488 | /* | |
489 | * Release any resources in case of a failure | |
490 | */ | |
ba253fbf | 491 | static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio) |
1da177e4 | 492 | { |
7b2c99d1 | 493 | while (sdio->head < sdio->tail) |
09cbfeaf | 494 | put_page(dio->pages[sdio->head++]); |
1da177e4 LT |
495 | } |
496 | ||
497 | /* | |
0273201e ZB |
498 | * Wait for the next BIO to complete. Remove it and return it. NULL is |
499 | * returned once all BIOs have been completed. This must only be called once | |
500 | * all bios have been issued so that dio->refcount can only decrease. This | |
501 | * requires that that the caller hold a reference on the dio. | |
1da177e4 LT |
502 | */ |
503 | static struct bio *dio_await_one(struct dio *dio) | |
504 | { | |
505 | unsigned long flags; | |
0273201e | 506 | struct bio *bio = NULL; |
1da177e4 LT |
507 | |
508 | spin_lock_irqsave(&dio->bio_lock, flags); | |
5eb6c7a2 ZB |
509 | |
510 | /* | |
511 | * Wait as long as the list is empty and there are bios in flight. bio | |
512 | * completion drops the count, maybe adds to the list, and wakes while | |
513 | * holding the bio_lock so we don't need set_current_state()'s barrier | |
514 | * and can call it after testing our condition. | |
515 | */ | |
516 | while (dio->refcount > 1 && dio->bio_list == NULL) { | |
517 | __set_current_state(TASK_UNINTERRUPTIBLE); | |
518 | dio->waiter = current; | |
519 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
c43c83a2 | 520 | if (!(dio->iocb->ki_flags & IOCB_HIPRI) || |
ea435e1b | 521 | !blk_poll(dio->bio_disk->queue, dio->bio_cookie)) |
15c4f638 | 522 | io_schedule(); |
5eb6c7a2 ZB |
523 | /* wake up sets us TASK_RUNNING */ |
524 | spin_lock_irqsave(&dio->bio_lock, flags); | |
525 | dio->waiter = NULL; | |
1da177e4 | 526 | } |
0273201e ZB |
527 | if (dio->bio_list) { |
528 | bio = dio->bio_list; | |
529 | dio->bio_list = bio->bi_private; | |
530 | } | |
1da177e4 LT |
531 | spin_unlock_irqrestore(&dio->bio_lock, flags); |
532 | return bio; | |
533 | } | |
534 | ||
535 | /* | |
536 | * Process one completed BIO. No locks are held. | |
537 | */ | |
4e4cbee9 | 538 | static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio) |
1da177e4 | 539 | { |
cb34e057 KO |
540 | struct bio_vec *bvec; |
541 | unsigned i; | |
4e4cbee9 | 542 | blk_status_t err = bio->bi_status; |
1da177e4 | 543 | |
03a07c92 GR |
544 | if (err) { |
545 | if (err == BLK_STS_AGAIN && (bio->bi_opf & REQ_NOWAIT)) | |
546 | dio->io_error = -EAGAIN; | |
547 | else | |
548 | dio->io_error = -EIO; | |
549 | } | |
1da177e4 | 550 | |
8a4c1e42 | 551 | if (dio->is_async && dio->op == REQ_OP_READ && dio->should_dirty) { |
7ddc971f | 552 | bio_check_pages_dirty(bio); /* transfers ownership */ |
1da177e4 | 553 | } else { |
cb34e057 KO |
554 | bio_for_each_segment_all(bvec, bio, i) { |
555 | struct page *page = bvec->bv_page; | |
1da177e4 | 556 | |
8a4c1e42 | 557 | if (dio->op == REQ_OP_READ && !PageCompound(page) && |
53cbf3b1 | 558 | dio->should_dirty) |
1da177e4 | 559 | set_page_dirty_lock(page); |
09cbfeaf | 560 | put_page(page); |
1da177e4 LT |
561 | } |
562 | bio_put(bio); | |
563 | } | |
9b81c842 | 564 | return err; |
1da177e4 LT |
565 | } |
566 | ||
567 | /* | |
0273201e ZB |
568 | * Wait on and process all in-flight BIOs. This must only be called once |
569 | * all bios have been issued so that the refcount can only decrease. | |
570 | * This just waits for all bios to make it through dio_bio_complete. IO | |
beb7dd86 | 571 | * errors are propagated through dio->io_error and should be propagated via |
0273201e | 572 | * dio_complete(). |
1da177e4 | 573 | */ |
6d544bb4 | 574 | static void dio_await_completion(struct dio *dio) |
1da177e4 | 575 | { |
0273201e ZB |
576 | struct bio *bio; |
577 | do { | |
578 | bio = dio_await_one(dio); | |
579 | if (bio) | |
580 | dio_bio_complete(dio, bio); | |
581 | } while (bio); | |
1da177e4 LT |
582 | } |
583 | ||
584 | /* | |
585 | * A really large O_DIRECT read or write can generate a lot of BIOs. So | |
586 | * to keep the memory consumption sane we periodically reap any completed BIOs | |
587 | * during the BIO generation phase. | |
588 | * | |
589 | * This also helps to limit the peak amount of pinned userspace memory. | |
590 | */ | |
ba253fbf | 591 | static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio) |
1da177e4 LT |
592 | { |
593 | int ret = 0; | |
594 | ||
eb28be2b | 595 | if (sdio->reap_counter++ >= 64) { |
1da177e4 LT |
596 | while (dio->bio_list) { |
597 | unsigned long flags; | |
598 | struct bio *bio; | |
599 | int ret2; | |
600 | ||
601 | spin_lock_irqsave(&dio->bio_lock, flags); | |
602 | bio = dio->bio_list; | |
603 | dio->bio_list = bio->bi_private; | |
604 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
4e4cbee9 | 605 | ret2 = blk_status_to_errno(dio_bio_complete(dio, bio)); |
1da177e4 LT |
606 | if (ret == 0) |
607 | ret = ret2; | |
608 | } | |
eb28be2b | 609 | sdio->reap_counter = 0; |
1da177e4 LT |
610 | } |
611 | return ret; | |
612 | } | |
613 | ||
7b7a8665 CH |
614 | /* |
615 | * Create workqueue for deferred direct IO completions. We allocate the | |
616 | * workqueue when it's first needed. This avoids creating workqueue for | |
617 | * filesystems that don't need it and also allows us to create the workqueue | |
618 | * late enough so the we can include s_id in the name of the workqueue. | |
619 | */ | |
ec1b8260 | 620 | int sb_init_dio_done_wq(struct super_block *sb) |
7b7a8665 | 621 | { |
45150c43 | 622 | struct workqueue_struct *old; |
7b7a8665 CH |
623 | struct workqueue_struct *wq = alloc_workqueue("dio/%s", |
624 | WQ_MEM_RECLAIM, 0, | |
625 | sb->s_id); | |
626 | if (!wq) | |
627 | return -ENOMEM; | |
628 | /* | |
629 | * This has to be atomic as more DIOs can race to create the workqueue | |
630 | */ | |
45150c43 | 631 | old = cmpxchg(&sb->s_dio_done_wq, NULL, wq); |
7b7a8665 | 632 | /* Someone created workqueue before us? Free ours... */ |
45150c43 | 633 | if (old) |
7b7a8665 CH |
634 | destroy_workqueue(wq); |
635 | return 0; | |
636 | } | |
637 | ||
638 | static int dio_set_defer_completion(struct dio *dio) | |
639 | { | |
640 | struct super_block *sb = dio->inode->i_sb; | |
641 | ||
642 | if (dio->defer_completion) | |
643 | return 0; | |
644 | dio->defer_completion = true; | |
645 | if (!sb->s_dio_done_wq) | |
646 | return sb_init_dio_done_wq(sb); | |
647 | return 0; | |
648 | } | |
649 | ||
1da177e4 LT |
650 | /* |
651 | * Call into the fs to map some more disk blocks. We record the current number | |
eb28be2b | 652 | * of available blocks at sdio->blocks_available. These are in units of the |
93407472 | 653 | * fs blocksize, i_blocksize(inode). |
1da177e4 LT |
654 | * |
655 | * The fs is allowed to map lots of blocks at once. If it wants to do that, | |
656 | * it uses the passed inode-relative block number as the file offset, as usual. | |
657 | * | |
1d8fa7a2 | 658 | * get_block() is passed the number of i_blkbits-sized blocks which direct_io |
1da177e4 LT |
659 | * has remaining to do. The fs should not map more than this number of blocks. |
660 | * | |
661 | * If the fs has mapped a lot of blocks, it should populate bh->b_size to | |
662 | * indicate how much contiguous disk space has been made available at | |
663 | * bh->b_blocknr. | |
664 | * | |
665 | * If *any* of the mapped blocks are new, then the fs must set buffer_new(). | |
666 | * This isn't very efficient... | |
667 | * | |
668 | * In the case of filesystem holes: the fs may return an arbitrarily-large | |
669 | * hole by returning an appropriate value in b_size and by clearing | |
670 | * buffer_mapped(). However the direct-io code will only process holes one | |
1d8fa7a2 | 671 | * block at a time - it will repeatedly call get_block() as it walks the hole. |
1da177e4 | 672 | */ |
18772641 AK |
673 | static int get_more_blocks(struct dio *dio, struct dio_submit *sdio, |
674 | struct buffer_head *map_bh) | |
1da177e4 LT |
675 | { |
676 | int ret; | |
1da177e4 | 677 | sector_t fs_startblk; /* Into file, in filesystem-sized blocks */ |
ae55e1aa | 678 | sector_t fs_endblk; /* Into file, in filesystem-sized blocks */ |
1da177e4 | 679 | unsigned long fs_count; /* Number of filesystem-sized blocks */ |
1da177e4 | 680 | int create; |
ab73857e | 681 | unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor; |
1da177e4 LT |
682 | |
683 | /* | |
684 | * If there was a memory error and we've overwritten all the | |
685 | * mapped blocks then we can now return that memory error | |
686 | */ | |
687 | ret = dio->page_errors; | |
688 | if (ret == 0) { | |
eb28be2b AK |
689 | BUG_ON(sdio->block_in_file >= sdio->final_block_in_request); |
690 | fs_startblk = sdio->block_in_file >> sdio->blkfactor; | |
ae55e1aa TM |
691 | fs_endblk = (sdio->final_block_in_request - 1) >> |
692 | sdio->blkfactor; | |
693 | fs_count = fs_endblk - fs_startblk + 1; | |
1da177e4 | 694 | |
3c674e74 | 695 | map_bh->b_state = 0; |
ab73857e | 696 | map_bh->b_size = fs_count << i_blkbits; |
3c674e74 | 697 | |
5fe878ae | 698 | /* |
9ecd10b7 EG |
699 | * For writes that could fill holes inside i_size on a |
700 | * DIO_SKIP_HOLES filesystem we forbid block creations: only | |
701 | * overwrites are permitted. We will return early to the caller | |
702 | * once we see an unmapped buffer head returned, and the caller | |
703 | * will fall back to buffered I/O. | |
5fe878ae CH |
704 | * |
705 | * Otherwise the decision is left to the get_blocks method, | |
706 | * which may decide to handle it or also return an unmapped | |
707 | * buffer head. | |
708 | */ | |
8a4c1e42 | 709 | create = dio->op == REQ_OP_WRITE; |
5fe878ae | 710 | if (dio->flags & DIO_SKIP_HOLES) { |
9ecd10b7 EG |
711 | if (fs_startblk <= ((i_size_read(dio->inode) - 1) >> |
712 | i_blkbits)) | |
1da177e4 | 713 | create = 0; |
1da177e4 | 714 | } |
3c674e74 | 715 | |
eb28be2b | 716 | ret = (*sdio->get_block)(dio->inode, fs_startblk, |
1da177e4 | 717 | map_bh, create); |
18772641 AK |
718 | |
719 | /* Store for completion */ | |
720 | dio->private = map_bh->b_private; | |
7b7a8665 CH |
721 | |
722 | if (ret == 0 && buffer_defer_completion(map_bh)) | |
723 | ret = dio_set_defer_completion(dio); | |
1da177e4 LT |
724 | } |
725 | return ret; | |
726 | } | |
727 | ||
728 | /* | |
729 | * There is no bio. Make one now. | |
730 | */ | |
ba253fbf AK |
731 | static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio, |
732 | sector_t start_sector, struct buffer_head *map_bh) | |
1da177e4 LT |
733 | { |
734 | sector_t sector; | |
735 | int ret, nr_pages; | |
736 | ||
eb28be2b | 737 | ret = dio_bio_reap(dio, sdio); |
1da177e4 LT |
738 | if (ret) |
739 | goto out; | |
eb28be2b | 740 | sector = start_sector << (sdio->blkbits - 9); |
b54ffb73 | 741 | nr_pages = min(sdio->pages_in_io, BIO_MAX_PAGES); |
1da177e4 | 742 | BUG_ON(nr_pages <= 0); |
18772641 | 743 | dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages); |
eb28be2b | 744 | sdio->boundary = 0; |
1da177e4 LT |
745 | out: |
746 | return ret; | |
747 | } | |
748 | ||
749 | /* | |
750 | * Attempt to put the current chunk of 'cur_page' into the current BIO. If | |
751 | * that was successful then update final_block_in_bio and take a ref against | |
752 | * the just-added page. | |
753 | * | |
754 | * Return zero on success. Non-zero means the caller needs to start a new BIO. | |
755 | */ | |
ba253fbf | 756 | static inline int dio_bio_add_page(struct dio_submit *sdio) |
1da177e4 LT |
757 | { |
758 | int ret; | |
759 | ||
eb28be2b AK |
760 | ret = bio_add_page(sdio->bio, sdio->cur_page, |
761 | sdio->cur_page_len, sdio->cur_page_offset); | |
762 | if (ret == sdio->cur_page_len) { | |
1da177e4 LT |
763 | /* |
764 | * Decrement count only, if we are done with this page | |
765 | */ | |
eb28be2b AK |
766 | if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE) |
767 | sdio->pages_in_io--; | |
09cbfeaf | 768 | get_page(sdio->cur_page); |
eb28be2b AK |
769 | sdio->final_block_in_bio = sdio->cur_page_block + |
770 | (sdio->cur_page_len >> sdio->blkbits); | |
1da177e4 LT |
771 | ret = 0; |
772 | } else { | |
773 | ret = 1; | |
774 | } | |
775 | return ret; | |
776 | } | |
777 | ||
778 | /* | |
779 | * Put cur_page under IO. The section of cur_page which is described by | |
780 | * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page | |
781 | * starts on-disk at cur_page_block. | |
782 | * | |
783 | * We take a ref against the page here (on behalf of its presence in the bio). | |
784 | * | |
785 | * The caller of this function is responsible for removing cur_page from the | |
786 | * dio, and for dropping the refcount which came from that presence. | |
787 | */ | |
ba253fbf AK |
788 | static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio, |
789 | struct buffer_head *map_bh) | |
1da177e4 LT |
790 | { |
791 | int ret = 0; | |
792 | ||
eb28be2b AK |
793 | if (sdio->bio) { |
794 | loff_t cur_offset = sdio->cur_page_fs_offset; | |
795 | loff_t bio_next_offset = sdio->logical_offset_in_bio + | |
4f024f37 | 796 | sdio->bio->bi_iter.bi_size; |
c2c6ca41 | 797 | |
1da177e4 | 798 | /* |
c2c6ca41 JB |
799 | * See whether this new request is contiguous with the old. |
800 | * | |
f0940cee NK |
801 | * Btrfs cannot handle having logically non-contiguous requests |
802 | * submitted. For example if you have | |
c2c6ca41 JB |
803 | * |
804 | * Logical: [0-4095][HOLE][8192-12287] | |
f0940cee | 805 | * Physical: [0-4095] [4096-8191] |
c2c6ca41 JB |
806 | * |
807 | * We cannot submit those pages together as one BIO. So if our | |
808 | * current logical offset in the file does not equal what would | |
809 | * be the next logical offset in the bio, submit the bio we | |
810 | * have. | |
1da177e4 | 811 | */ |
eb28be2b | 812 | if (sdio->final_block_in_bio != sdio->cur_page_block || |
c2c6ca41 | 813 | cur_offset != bio_next_offset) |
eb28be2b | 814 | dio_bio_submit(dio, sdio); |
1da177e4 LT |
815 | } |
816 | ||
eb28be2b | 817 | if (sdio->bio == NULL) { |
18772641 | 818 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 LT |
819 | if (ret) |
820 | goto out; | |
821 | } | |
822 | ||
eb28be2b AK |
823 | if (dio_bio_add_page(sdio) != 0) { |
824 | dio_bio_submit(dio, sdio); | |
18772641 | 825 | ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh); |
1da177e4 | 826 | if (ret == 0) { |
eb28be2b | 827 | ret = dio_bio_add_page(sdio); |
1da177e4 LT |
828 | BUG_ON(ret != 0); |
829 | } | |
830 | } | |
831 | out: | |
832 | return ret; | |
833 | } | |
834 | ||
835 | /* | |
836 | * An autonomous function to put a chunk of a page under deferred IO. | |
837 | * | |
838 | * The caller doesn't actually know (or care) whether this piece of page is in | |
839 | * a BIO, or is under IO or whatever. We just take care of all possible | |
840 | * situations here. The separation between the logic of do_direct_IO() and | |
841 | * that of submit_page_section() is important for clarity. Please don't break. | |
842 | * | |
843 | * The chunk of page starts on-disk at blocknr. | |
844 | * | |
845 | * We perform deferred IO, by recording the last-submitted page inside our | |
846 | * private part of the dio structure. If possible, we just expand the IO | |
847 | * across that page here. | |
848 | * | |
849 | * If that doesn't work out then we put the old page into the bio and add this | |
850 | * page to the dio instead. | |
851 | */ | |
ba253fbf | 852 | static inline int |
eb28be2b | 853 | submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page, |
18772641 AK |
854 | unsigned offset, unsigned len, sector_t blocknr, |
855 | struct buffer_head *map_bh) | |
1da177e4 LT |
856 | { |
857 | int ret = 0; | |
858 | ||
8a4c1e42 | 859 | if (dio->op == REQ_OP_WRITE) { |
98c4d57d AM |
860 | /* |
861 | * Read accounting is performed in submit_bio() | |
862 | */ | |
863 | task_io_account_write(len); | |
864 | } | |
865 | ||
1da177e4 LT |
866 | /* |
867 | * Can we just grow the current page's presence in the dio? | |
868 | */ | |
eb28be2b AK |
869 | if (sdio->cur_page == page && |
870 | sdio->cur_page_offset + sdio->cur_page_len == offset && | |
871 | sdio->cur_page_block + | |
872 | (sdio->cur_page_len >> sdio->blkbits) == blocknr) { | |
873 | sdio->cur_page_len += len; | |
1da177e4 LT |
874 | goto out; |
875 | } | |
876 | ||
877 | /* | |
878 | * If there's a deferred page already there then send it. | |
879 | */ | |
eb28be2b | 880 | if (sdio->cur_page) { |
18772641 | 881 | ret = dio_send_cur_page(dio, sdio, map_bh); |
09cbfeaf | 882 | put_page(sdio->cur_page); |
eb28be2b | 883 | sdio->cur_page = NULL; |
1da177e4 | 884 | if (ret) |
b1058b98 | 885 | return ret; |
1da177e4 LT |
886 | } |
887 | ||
09cbfeaf | 888 | get_page(page); /* It is in dio */ |
eb28be2b AK |
889 | sdio->cur_page = page; |
890 | sdio->cur_page_offset = offset; | |
891 | sdio->cur_page_len = len; | |
892 | sdio->cur_page_block = blocknr; | |
893 | sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits; | |
1da177e4 | 894 | out: |
b1058b98 JK |
895 | /* |
896 | * If sdio->boundary then we want to schedule the IO now to | |
897 | * avoid metadata seeks. | |
898 | */ | |
899 | if (sdio->boundary) { | |
900 | ret = dio_send_cur_page(dio, sdio, map_bh); | |
899f0429 AG |
901 | if (sdio->bio) |
902 | dio_bio_submit(dio, sdio); | |
09cbfeaf | 903 | put_page(sdio->cur_page); |
b1058b98 JK |
904 | sdio->cur_page = NULL; |
905 | } | |
1da177e4 LT |
906 | return ret; |
907 | } | |
908 | ||
1da177e4 LT |
909 | /* |
910 | * If we are not writing the entire block and get_block() allocated | |
911 | * the block for us, we need to fill-in the unused portion of the | |
912 | * block with zeros. This happens only if user-buffer, fileoffset or | |
913 | * io length is not filesystem block-size multiple. | |
914 | * | |
915 | * `end' is zero if we're doing the start of the IO, 1 at the end of the | |
916 | * IO. | |
917 | */ | |
ba253fbf AK |
918 | static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio, |
919 | int end, struct buffer_head *map_bh) | |
1da177e4 LT |
920 | { |
921 | unsigned dio_blocks_per_fs_block; | |
922 | unsigned this_chunk_blocks; /* In dio_blocks */ | |
923 | unsigned this_chunk_bytes; | |
924 | struct page *page; | |
925 | ||
eb28be2b | 926 | sdio->start_zero_done = 1; |
18772641 | 927 | if (!sdio->blkfactor || !buffer_new(map_bh)) |
1da177e4 LT |
928 | return; |
929 | ||
eb28be2b AK |
930 | dio_blocks_per_fs_block = 1 << sdio->blkfactor; |
931 | this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1); | |
1da177e4 LT |
932 | |
933 | if (!this_chunk_blocks) | |
934 | return; | |
935 | ||
936 | /* | |
937 | * We need to zero out part of an fs block. It is either at the | |
938 | * beginning or the end of the fs block. | |
939 | */ | |
940 | if (end) | |
941 | this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks; | |
942 | ||
eb28be2b | 943 | this_chunk_bytes = this_chunk_blocks << sdio->blkbits; |
1da177e4 | 944 | |
557ed1fa | 945 | page = ZERO_PAGE(0); |
eb28be2b | 946 | if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes, |
18772641 | 947 | sdio->next_block_for_io, map_bh)) |
1da177e4 LT |
948 | return; |
949 | ||
eb28be2b | 950 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 LT |
951 | } |
952 | ||
953 | /* | |
954 | * Walk the user pages, and the file, mapping blocks to disk and generating | |
955 | * a sequence of (page,offset,len,block) mappings. These mappings are injected | |
956 | * into submit_page_section(), which takes care of the next stage of submission | |
957 | * | |
958 | * Direct IO against a blockdev is different from a file. Because we can | |
959 | * happily perform page-sized but 512-byte aligned IOs. It is important that | |
960 | * blockdev IO be able to have fine alignment and large sizes. | |
961 | * | |
1d8fa7a2 | 962 | * So what we do is to permit the ->get_block function to populate bh.b_size |
1da177e4 LT |
963 | * with the size of IO which is permitted at this offset and this i_blkbits. |
964 | * | |
965 | * For best results, the blockdev should be set up with 512-byte i_blkbits and | |
1d8fa7a2 | 966 | * it should set b_size to PAGE_SIZE or more inside get_block(). This gives |
1da177e4 LT |
967 | * fine alignment but still allows this function to work in PAGE_SIZE units. |
968 | */ | |
18772641 AK |
969 | static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, |
970 | struct buffer_head *map_bh) | |
1da177e4 | 971 | { |
eb28be2b | 972 | const unsigned blkbits = sdio->blkbits; |
dd545b52 | 973 | const unsigned i_blkbits = blkbits + sdio->blkfactor; |
1da177e4 LT |
974 | int ret = 0; |
975 | ||
eb28be2b | 976 | while (sdio->block_in_file < sdio->final_block_in_request) { |
7b2c99d1 AV |
977 | struct page *page; |
978 | size_t from, to; | |
6fcc5420 BH |
979 | |
980 | page = dio_get_page(dio, sdio); | |
1da177e4 LT |
981 | if (IS_ERR(page)) { |
982 | ret = PTR_ERR(page); | |
983 | goto out; | |
984 | } | |
6fcc5420 BH |
985 | from = sdio->head ? 0 : sdio->from; |
986 | to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE; | |
987 | sdio->head++; | |
1da177e4 | 988 | |
7b2c99d1 | 989 | while (from < to) { |
1da177e4 LT |
990 | unsigned this_chunk_bytes; /* # of bytes mapped */ |
991 | unsigned this_chunk_blocks; /* # of blocks */ | |
992 | unsigned u; | |
993 | ||
eb28be2b | 994 | if (sdio->blocks_available == 0) { |
1da177e4 LT |
995 | /* |
996 | * Need to go and map some more disk | |
997 | */ | |
998 | unsigned long blkmask; | |
999 | unsigned long dio_remainder; | |
1000 | ||
18772641 | 1001 | ret = get_more_blocks(dio, sdio, map_bh); |
1da177e4 | 1002 | if (ret) { |
09cbfeaf | 1003 | put_page(page); |
1da177e4 LT |
1004 | goto out; |
1005 | } | |
1006 | if (!buffer_mapped(map_bh)) | |
1007 | goto do_holes; | |
1008 | ||
eb28be2b | 1009 | sdio->blocks_available = |
f734c89c | 1010 | map_bh->b_size >> blkbits; |
eb28be2b AK |
1011 | sdio->next_block_for_io = |
1012 | map_bh->b_blocknr << sdio->blkfactor; | |
f734c89c JK |
1013 | if (buffer_new(map_bh)) { |
1014 | clean_bdev_aliases( | |
1015 | map_bh->b_bdev, | |
1016 | map_bh->b_blocknr, | |
dd545b52 | 1017 | map_bh->b_size >> i_blkbits); |
f734c89c | 1018 | } |
1da177e4 | 1019 | |
eb28be2b | 1020 | if (!sdio->blkfactor) |
1da177e4 LT |
1021 | goto do_holes; |
1022 | ||
eb28be2b AK |
1023 | blkmask = (1 << sdio->blkfactor) - 1; |
1024 | dio_remainder = (sdio->block_in_file & blkmask); | |
1da177e4 LT |
1025 | |
1026 | /* | |
1027 | * If we are at the start of IO and that IO | |
1028 | * starts partway into a fs-block, | |
1029 | * dio_remainder will be non-zero. If the IO | |
1030 | * is a read then we can simply advance the IO | |
1031 | * cursor to the first block which is to be | |
1032 | * read. But if the IO is a write and the | |
1033 | * block was newly allocated we cannot do that; | |
1034 | * the start of the fs block must be zeroed out | |
1035 | * on-disk | |
1036 | */ | |
1037 | if (!buffer_new(map_bh)) | |
eb28be2b AK |
1038 | sdio->next_block_for_io += dio_remainder; |
1039 | sdio->blocks_available -= dio_remainder; | |
1da177e4 LT |
1040 | } |
1041 | do_holes: | |
1042 | /* Handle holes */ | |
1043 | if (!buffer_mapped(map_bh)) { | |
35dc8161 | 1044 | loff_t i_size_aligned; |
1da177e4 LT |
1045 | |
1046 | /* AKPM: eargh, -ENOTBLK is a hack */ | |
8a4c1e42 | 1047 | if (dio->op == REQ_OP_WRITE) { |
09cbfeaf | 1048 | put_page(page); |
1da177e4 LT |
1049 | return -ENOTBLK; |
1050 | } | |
1051 | ||
35dc8161 JM |
1052 | /* |
1053 | * Be sure to account for a partial block as the | |
1054 | * last block in the file | |
1055 | */ | |
1056 | i_size_aligned = ALIGN(i_size_read(dio->inode), | |
1057 | 1 << blkbits); | |
eb28be2b | 1058 | if (sdio->block_in_file >= |
35dc8161 | 1059 | i_size_aligned >> blkbits) { |
1da177e4 | 1060 | /* We hit eof */ |
09cbfeaf | 1061 | put_page(page); |
1da177e4 LT |
1062 | goto out; |
1063 | } | |
7b2c99d1 | 1064 | zero_user(page, from, 1 << blkbits); |
eb28be2b | 1065 | sdio->block_in_file++; |
7b2c99d1 | 1066 | from += 1 << blkbits; |
3320c60b | 1067 | dio->result += 1 << blkbits; |
1da177e4 LT |
1068 | goto next_block; |
1069 | } | |
1070 | ||
1071 | /* | |
1072 | * If we're performing IO which has an alignment which | |
1073 | * is finer than the underlying fs, go check to see if | |
1074 | * we must zero out the start of this block. | |
1075 | */ | |
eb28be2b | 1076 | if (unlikely(sdio->blkfactor && !sdio->start_zero_done)) |
18772641 | 1077 | dio_zero_block(dio, sdio, 0, map_bh); |
1da177e4 LT |
1078 | |
1079 | /* | |
1080 | * Work out, in this_chunk_blocks, how much disk we | |
1081 | * can add to this page | |
1082 | */ | |
eb28be2b | 1083 | this_chunk_blocks = sdio->blocks_available; |
7b2c99d1 | 1084 | u = (to - from) >> blkbits; |
1da177e4 LT |
1085 | if (this_chunk_blocks > u) |
1086 | this_chunk_blocks = u; | |
eb28be2b | 1087 | u = sdio->final_block_in_request - sdio->block_in_file; |
1da177e4 LT |
1088 | if (this_chunk_blocks > u) |
1089 | this_chunk_blocks = u; | |
1090 | this_chunk_bytes = this_chunk_blocks << blkbits; | |
1091 | BUG_ON(this_chunk_bytes == 0); | |
1092 | ||
092c8d46 JK |
1093 | if (this_chunk_blocks == sdio->blocks_available) |
1094 | sdio->boundary = buffer_boundary(map_bh); | |
eb28be2b | 1095 | ret = submit_page_section(dio, sdio, page, |
7b2c99d1 | 1096 | from, |
eb28be2b | 1097 | this_chunk_bytes, |
18772641 AK |
1098 | sdio->next_block_for_io, |
1099 | map_bh); | |
1da177e4 | 1100 | if (ret) { |
09cbfeaf | 1101 | put_page(page); |
1da177e4 LT |
1102 | goto out; |
1103 | } | |
eb28be2b | 1104 | sdio->next_block_for_io += this_chunk_blocks; |
1da177e4 | 1105 | |
eb28be2b | 1106 | sdio->block_in_file += this_chunk_blocks; |
7b2c99d1 AV |
1107 | from += this_chunk_bytes; |
1108 | dio->result += this_chunk_bytes; | |
eb28be2b | 1109 | sdio->blocks_available -= this_chunk_blocks; |
1da177e4 | 1110 | next_block: |
eb28be2b AK |
1111 | BUG_ON(sdio->block_in_file > sdio->final_block_in_request); |
1112 | if (sdio->block_in_file == sdio->final_block_in_request) | |
1da177e4 LT |
1113 | break; |
1114 | } | |
1115 | ||
1116 | /* Drop the ref which was taken in get_user_pages() */ | |
09cbfeaf | 1117 | put_page(page); |
1da177e4 LT |
1118 | } |
1119 | out: | |
1120 | return ret; | |
1121 | } | |
1122 | ||
847cc637 | 1123 | static inline int drop_refcount(struct dio *dio) |
1da177e4 | 1124 | { |
847cc637 | 1125 | int ret2; |
5eb6c7a2 | 1126 | unsigned long flags; |
1da177e4 | 1127 | |
8459d86a ZB |
1128 | /* |
1129 | * Sync will always be dropping the final ref and completing the | |
5eb6c7a2 ZB |
1130 | * operation. AIO can if it was a broken operation described above or |
1131 | * in fact if all the bios race to complete before we get here. In | |
1132 | * that case dio_complete() translates the EIOCBQUEUED into the proper | |
04b2fa9f | 1133 | * return code that the caller will hand to ->complete(). |
5eb6c7a2 ZB |
1134 | * |
1135 | * This is managed by the bio_lock instead of being an atomic_t so that | |
1136 | * completion paths can drop their ref and use the remaining count to | |
1137 | * decide to wake the submission path atomically. | |
8459d86a | 1138 | */ |
5eb6c7a2 ZB |
1139 | spin_lock_irqsave(&dio->bio_lock, flags); |
1140 | ret2 = --dio->refcount; | |
1141 | spin_unlock_irqrestore(&dio->bio_lock, flags); | |
847cc637 | 1142 | return ret2; |
1da177e4 LT |
1143 | } |
1144 | ||
eafdc7d1 CH |
1145 | /* |
1146 | * This is a library function for use by filesystem drivers. | |
1147 | * | |
1148 | * The locking rules are governed by the flags parameter: | |
1149 | * - if the flags value contains DIO_LOCKING we use a fancy locking | |
1150 | * scheme for dumb filesystems. | |
1151 | * For writes this function is called under i_mutex and returns with | |
1152 | * i_mutex held, for reads, i_mutex is not held on entry, but it is | |
1153 | * taken and dropped again before returning. | |
eafdc7d1 CH |
1154 | * - if the flags value does NOT contain DIO_LOCKING we don't use any |
1155 | * internal locking but rather rely on the filesystem to synchronize | |
1156 | * direct I/O reads/writes versus each other and truncate. | |
df2d6f26 CH |
1157 | * |
1158 | * To help with locking against truncate we incremented the i_dio_count | |
1159 | * counter before starting direct I/O, and decrement it once we are done. | |
1160 | * Truncate can wait for it to reach zero to provide exclusion. It is | |
1161 | * expected that filesystem provide exclusion between new direct I/O | |
1162 | * and truncates. For DIO_LOCKING filesystems this is done by i_mutex, | |
1163 | * but other filesystems need to take care of this on their own. | |
ba253fbf AK |
1164 | * |
1165 | * NOTE: if you pass "sdio" to anything by pointer make sure that function | |
1166 | * is always inlined. Otherwise gcc is unable to split the structure into | |
1167 | * individual fields and will generate much worse code. This is important | |
1168 | * for the whole file. | |
eafdc7d1 | 1169 | */ |
65dd2aa9 | 1170 | static inline ssize_t |
17f8c842 OS |
1171 | do_blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, |
1172 | struct block_device *bdev, struct iov_iter *iter, | |
c8b8e32d | 1173 | get_block_t get_block, dio_iodone_t end_io, |
17f8c842 | 1174 | dio_submit_t submit_io, int flags) |
1da177e4 | 1175 | { |
6aa7de05 | 1176 | unsigned i_blkbits = READ_ONCE(inode->i_blkbits); |
ab73857e | 1177 | unsigned blkbits = i_blkbits; |
1da177e4 LT |
1178 | unsigned blocksize_mask = (1 << blkbits) - 1; |
1179 | ssize_t retval = -EINVAL; | |
1c0ff0f1 | 1180 | const size_t count = iov_iter_count(iter); |
c8b8e32d | 1181 | loff_t offset = iocb->ki_pos; |
1c0ff0f1 | 1182 | const loff_t end = offset + count; |
1da177e4 | 1183 | struct dio *dio; |
eb28be2b | 1184 | struct dio_submit sdio = { 0, }; |
847cc637 | 1185 | struct buffer_head map_bh = { 0, }; |
647d1e4c | 1186 | struct blk_plug plug; |
886a3911 | 1187 | unsigned long align = offset | iov_iter_alignment(iter); |
1da177e4 | 1188 | |
65dd2aa9 AK |
1189 | /* |
1190 | * Avoid references to bdev if not absolutely needed to give | |
1191 | * the early prefetch in the caller enough time. | |
1192 | */ | |
1da177e4 | 1193 | |
886a3911 | 1194 | if (align & blocksize_mask) { |
1da177e4 | 1195 | if (bdev) |
65dd2aa9 | 1196 | blkbits = blksize_bits(bdev_logical_block_size(bdev)); |
1da177e4 | 1197 | blocksize_mask = (1 << blkbits) - 1; |
886a3911 | 1198 | if (align & blocksize_mask) |
1da177e4 LT |
1199 | goto out; |
1200 | } | |
1201 | ||
f9b5570d | 1202 | /* watch out for a 0 len io from a tricksy fs */ |
1c0ff0f1 | 1203 | if (iov_iter_rw(iter) == READ && !count) |
f9b5570d CH |
1204 | return 0; |
1205 | ||
6e8267f5 | 1206 | dio = kmem_cache_alloc(dio_cache, GFP_KERNEL); |
1da177e4 LT |
1207 | retval = -ENOMEM; |
1208 | if (!dio) | |
1209 | goto out; | |
23aee091 JM |
1210 | /* |
1211 | * Believe it or not, zeroing out the page array caused a .5% | |
1212 | * performance regression in a database benchmark. So, we take | |
1213 | * care to only zero out what's needed. | |
1214 | */ | |
1215 | memset(dio, 0, offsetof(struct dio, pages)); | |
1da177e4 | 1216 | |
5fe878ae CH |
1217 | dio->flags = flags; |
1218 | if (dio->flags & DIO_LOCKING) { | |
17f8c842 | 1219 | if (iov_iter_rw(iter) == READ) { |
5fe878ae CH |
1220 | struct address_space *mapping = |
1221 | iocb->ki_filp->f_mapping; | |
1da177e4 | 1222 | |
5fe878ae | 1223 | /* will be released by direct_io_worker */ |
5955102c | 1224 | inode_lock(inode); |
1da177e4 LT |
1225 | |
1226 | retval = filemap_write_and_wait_range(mapping, offset, | |
1227 | end - 1); | |
1228 | if (retval) { | |
5955102c | 1229 | inode_unlock(inode); |
6e8267f5 | 1230 | kmem_cache_free(dio_cache, dio); |
1da177e4 LT |
1231 | goto out; |
1232 | } | |
1da177e4 | 1233 | } |
1da177e4 LT |
1234 | } |
1235 | ||
74cedf9b JK |
1236 | /* Once we sampled i_size check for reads beyond EOF */ |
1237 | dio->i_size = i_size_read(inode); | |
1238 | if (iov_iter_rw(iter) == READ && offset >= dio->i_size) { | |
1239 | if (dio->flags & DIO_LOCKING) | |
5955102c | 1240 | inode_unlock(inode); |
74cedf9b | 1241 | kmem_cache_free(dio_cache, dio); |
2d4594ac | 1242 | retval = 0; |
74cedf9b JK |
1243 | goto out; |
1244 | } | |
1245 | ||
1da177e4 | 1246 | /* |
60392573 CH |
1247 | * For file extending writes updating i_size before data writeouts |
1248 | * complete can expose uninitialized blocks in dumb filesystems. | |
1249 | * In that case we need to wait for I/O completion even if asked | |
1250 | * for an asynchronous write. | |
1da177e4 | 1251 | */ |
60392573 CH |
1252 | if (is_sync_kiocb(iocb)) |
1253 | dio->is_async = false; | |
c8f4c36f | 1254 | else if (iov_iter_rw(iter) == WRITE && end > i_size_read(inode)) |
60392573 CH |
1255 | dio->is_async = false; |
1256 | else | |
1257 | dio->is_async = true; | |
1258 | ||
847cc637 | 1259 | dio->inode = inode; |
8a4c1e42 MC |
1260 | if (iov_iter_rw(iter) == WRITE) { |
1261 | dio->op = REQ_OP_WRITE; | |
70fd7614 | 1262 | dio->op_flags = REQ_SYNC | REQ_IDLE; |
03a07c92 GR |
1263 | if (iocb->ki_flags & IOCB_NOWAIT) |
1264 | dio->op_flags |= REQ_NOWAIT; | |
8a4c1e42 MC |
1265 | } else { |
1266 | dio->op = REQ_OP_READ; | |
1267 | } | |
02afc27f CH |
1268 | |
1269 | /* | |
1270 | * For AIO O_(D)SYNC writes we need to defer completions to a workqueue | |
1271 | * so that we can call ->fsync. | |
1272 | */ | |
332391a9 LC |
1273 | if (dio->is_async && iov_iter_rw(iter) == WRITE) { |
1274 | retval = 0; | |
d9c10e5b | 1275 | if (iocb->ki_flags & IOCB_DSYNC) |
332391a9 LC |
1276 | retval = dio_set_defer_completion(dio); |
1277 | else if (!dio->inode->i_sb->s_dio_done_wq) { | |
1278 | /* | |
1279 | * In case of AIO write racing with buffered read we | |
1280 | * need to defer completion. We can't decide this now, | |
1281 | * however the workqueue needs to be initialized here. | |
1282 | */ | |
1283 | retval = sb_init_dio_done_wq(dio->inode->i_sb); | |
1284 | } | |
02afc27f CH |
1285 | if (retval) { |
1286 | /* | |
1287 | * We grab i_mutex only for reads so we don't have | |
1288 | * to release it here | |
1289 | */ | |
1290 | kmem_cache_free(dio_cache, dio); | |
1291 | goto out; | |
1292 | } | |
1293 | } | |
1294 | ||
1295 | /* | |
1296 | * Will be decremented at I/O completion time. | |
1297 | */ | |
ce3077ee | 1298 | inode_dio_begin(inode); |
02afc27f CH |
1299 | |
1300 | retval = 0; | |
847cc637 | 1301 | sdio.blkbits = blkbits; |
ab73857e | 1302 | sdio.blkfactor = i_blkbits - blkbits; |
847cc637 AK |
1303 | sdio.block_in_file = offset >> blkbits; |
1304 | ||
1305 | sdio.get_block = get_block; | |
1306 | dio->end_io = end_io; | |
1307 | sdio.submit_io = submit_io; | |
1308 | sdio.final_block_in_bio = -1; | |
1309 | sdio.next_block_for_io = -1; | |
1310 | ||
1311 | dio->iocb = iocb; | |
847cc637 AK |
1312 | |
1313 | spin_lock_init(&dio->bio_lock); | |
1314 | dio->refcount = 1; | |
1315 | ||
00e23707 | 1316 | dio->should_dirty = iter_is_iovec(iter) && iov_iter_rw(iter) == READ; |
7b2c99d1 | 1317 | sdio.iter = iter; |
1c0ff0f1 | 1318 | sdio.final_block_in_request = end >> blkbits; |
7b2c99d1 | 1319 | |
847cc637 AK |
1320 | /* |
1321 | * In case of non-aligned buffers, we may need 2 more | |
1322 | * pages since we need to zero out first and last block. | |
1323 | */ | |
1324 | if (unlikely(sdio.blkfactor)) | |
1325 | sdio.pages_in_io = 2; | |
1326 | ||
f67da30c | 1327 | sdio.pages_in_io += iov_iter_npages(iter, INT_MAX); |
847cc637 | 1328 | |
647d1e4c FW |
1329 | blk_start_plug(&plug); |
1330 | ||
7b2c99d1 AV |
1331 | retval = do_direct_IO(dio, &sdio, &map_bh); |
1332 | if (retval) | |
1333 | dio_cleanup(dio, &sdio); | |
847cc637 AK |
1334 | |
1335 | if (retval == -ENOTBLK) { | |
1336 | /* | |
1337 | * The remaining part of the request will be | |
1338 | * be handled by buffered I/O when we return | |
1339 | */ | |
1340 | retval = 0; | |
1341 | } | |
1342 | /* | |
1343 | * There may be some unwritten disk at the end of a part-written | |
1344 | * fs-block-sized block. Go zero that now. | |
1345 | */ | |
1346 | dio_zero_block(dio, &sdio, 1, &map_bh); | |
1347 | ||
1348 | if (sdio.cur_page) { | |
1349 | ssize_t ret2; | |
1350 | ||
1351 | ret2 = dio_send_cur_page(dio, &sdio, &map_bh); | |
1352 | if (retval == 0) | |
1353 | retval = ret2; | |
09cbfeaf | 1354 | put_page(sdio.cur_page); |
847cc637 AK |
1355 | sdio.cur_page = NULL; |
1356 | } | |
1357 | if (sdio.bio) | |
1358 | dio_bio_submit(dio, &sdio); | |
1359 | ||
647d1e4c FW |
1360 | blk_finish_plug(&plug); |
1361 | ||
847cc637 AK |
1362 | /* |
1363 | * It is possible that, we return short IO due to end of file. | |
1364 | * In that case, we need to release all the pages we got hold on. | |
1365 | */ | |
1366 | dio_cleanup(dio, &sdio); | |
1367 | ||
1368 | /* | |
1369 | * All block lookups have been performed. For READ requests | |
1370 | * we can let i_mutex go now that its achieved its purpose | |
1371 | * of protecting us from looking up uninitialized blocks. | |
1372 | */ | |
17f8c842 | 1373 | if (iov_iter_rw(iter) == READ && (dio->flags & DIO_LOCKING)) |
5955102c | 1374 | inode_unlock(dio->inode); |
847cc637 AK |
1375 | |
1376 | /* | |
1377 | * The only time we want to leave bios in flight is when a successful | |
1378 | * partial aio read or full aio write have been setup. In that case | |
1379 | * bio completion will call aio_complete. The only time it's safe to | |
1380 | * call aio_complete is when we return -EIOCBQUEUED, so we key on that. | |
1381 | * This had *better* be the only place that raises -EIOCBQUEUED. | |
1382 | */ | |
1383 | BUG_ON(retval == -EIOCBQUEUED); | |
1384 | if (dio->is_async && retval == 0 && dio->result && | |
17f8c842 | 1385 | (iov_iter_rw(iter) == READ || dio->result == count)) |
847cc637 | 1386 | retval = -EIOCBQUEUED; |
af436472 | 1387 | else |
847cc637 AK |
1388 | dio_await_completion(dio); |
1389 | ||
1390 | if (drop_refcount(dio) == 0) { | |
ffe51f01 | 1391 | retval = dio_complete(dio, retval, DIO_COMPLETE_INVALIDATE); |
847cc637 AK |
1392 | } else |
1393 | BUG_ON(retval != -EIOCBQUEUED); | |
1da177e4 | 1394 | |
7bb46a67 | 1395 | out: |
1396 | return retval; | |
1397 | } | |
65dd2aa9 | 1398 | |
17f8c842 OS |
1399 | ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode, |
1400 | struct block_device *bdev, struct iov_iter *iter, | |
c8b8e32d | 1401 | get_block_t get_block, |
17f8c842 OS |
1402 | dio_iodone_t end_io, dio_submit_t submit_io, |
1403 | int flags) | |
65dd2aa9 AK |
1404 | { |
1405 | /* | |
1406 | * The block device state is needed in the end to finally | |
1407 | * submit everything. Since it's likely to be cache cold | |
1408 | * prefetch it here as first thing to hide some of the | |
1409 | * latency. | |
1410 | * | |
1411 | * Attempt to prefetch the pieces we likely need later. | |
1412 | */ | |
1413 | prefetch(&bdev->bd_disk->part_tbl); | |
1414 | prefetch(bdev->bd_queue); | |
1415 | prefetch((char *)bdev->bd_queue + SMP_CACHE_BYTES); | |
1416 | ||
c8b8e32d | 1417 | return do_blockdev_direct_IO(iocb, inode, bdev, iter, get_block, |
17f8c842 | 1418 | end_io, submit_io, flags); |
65dd2aa9 AK |
1419 | } |
1420 | ||
1da177e4 | 1421 | EXPORT_SYMBOL(__blockdev_direct_IO); |
6e8267f5 AK |
1422 | |
1423 | static __init int dio_init(void) | |
1424 | { | |
1425 | dio_cache = KMEM_CACHE(dio, SLAB_PANIC); | |
1426 | return 0; | |
1427 | } | |
1428 | module_init(dio_init) |