1 // SPDX-License-Identifier: GPL-2.0-only 1 // SPDX-License-Identifier: GPL-2.0-only
2 /* 2 /*
3 * fs/direct-io.c 3 * fs/direct-io.c
4 * 4 *
5 * Copyright (C) 2002, Linus Torvalds. 5 * Copyright (C) 2002, Linus Torvalds.
6 * 6 *
7 * O_DIRECT 7 * O_DIRECT
8 * 8 *
9 * 04Jul2002 Andrew Morton 9 * 04Jul2002 Andrew Morton
10 * Initial version 10 * Initial version
11 * 11Sep2002 janetinc@us.ibm.com 11 * 11Sep2002 janetinc@us.ibm.com
12 * added readv/writev support. 12 * added readv/writev support.
13 * 29Oct2002 Andrew Morton 13 * 29Oct2002 Andrew Morton
14 * rewrote bio_add_page() support 14 * rewrote bio_add_page() support.
15 * 30Oct2002 pbadari@us.ibm.com 15 * 30Oct2002 pbadari@us.ibm.com
16 * added support for non-aligned 16 * added support for non-aligned IO.
17 * 06Nov2002 pbadari@us.ibm.com 17 * 06Nov2002 pbadari@us.ibm.com
18 * added asynchronous IO support. 18 * added asynchronous IO support.
19 * 21Jul2003 nathans@sgi.com 19 * 21Jul2003 nathans@sgi.com
20 * added IO completion notifier. 20 * added IO completion notifier.
21 */ 21 */
22 22
23 #include <linux/kernel.h> 23 #include <linux/kernel.h>
24 #include <linux/module.h> 24 #include <linux/module.h>
25 #include <linux/types.h> 25 #include <linux/types.h>
26 #include <linux/fs.h> 26 #include <linux/fs.h>
27 #include <linux/mm.h> 27 #include <linux/mm.h>
28 #include <linux/slab.h> 28 #include <linux/slab.h>
29 #include <linux/highmem.h> 29 #include <linux/highmem.h>
30 #include <linux/pagemap.h> 30 #include <linux/pagemap.h>
31 #include <linux/task_io_accounting_ops.h> 31 #include <linux/task_io_accounting_ops.h>
32 #include <linux/bio.h> 32 #include <linux/bio.h>
33 #include <linux/wait.h> 33 #include <linux/wait.h>
34 #include <linux/err.h> 34 #include <linux/err.h>
35 #include <linux/blkdev.h> 35 #include <linux/blkdev.h>
36 #include <linux/buffer_head.h> 36 #include <linux/buffer_head.h>
37 #include <linux/rwsem.h> 37 #include <linux/rwsem.h>
38 #include <linux/uio.h> 38 #include <linux/uio.h>
39 #include <linux/atomic.h> 39 #include <linux/atomic.h>
>> 40 #include <linux/prefetch.h>
40 41
41 #include "internal.h" 42 #include "internal.h"
42 43
43 /* 44 /*
44 * How many user pages to map in one call to i !! 45 * How many user pages to map in one call to get_user_pages(). This determines
45 * determines the size of a structure in the s !! 46 * the size of a structure in the slab cache
46 */ 47 */
47 #define DIO_PAGES 64 48 #define DIO_PAGES 64
48 49
49 /* 50 /*
50 * Flags for dio_complete() 51 * Flags for dio_complete()
51 */ 52 */
52 #define DIO_COMPLETE_ASYNC 0x01 53 #define DIO_COMPLETE_ASYNC 0x01 /* This is async IO */
53 #define DIO_COMPLETE_INVALIDATE 0x02 54 #define DIO_COMPLETE_INVALIDATE 0x02 /* Can invalidate pages */
54 55
55 /* 56 /*
56 * This code generally works in units of "dio_ 57 * This code generally works in units of "dio_blocks". A dio_block is
57 * somewhere between the hard sector size and 58 * somewhere between the hard sector size and the filesystem block size. it
58 * is determined on a per-invocation basis. 59 * is determined on a per-invocation basis. When talking to the filesystem
59 * we need to convert dio_blocks to fs_blocks 60 * we need to convert dio_blocks to fs_blocks by scaling the dio_block quantity
60 * down by dio->blkfactor. Similarly, fs-bloc 61 * down by dio->blkfactor. Similarly, fs-blocksize quantities are converted
61 * to bio_block quantities by shifting left by 62 * to bio_block quantities by shifting left by blkfactor.
62 * 63 *
63 * If blkfactor is zero then the user's reques 64 * If blkfactor is zero then the user's request was aligned to the filesystem's
64 * blocksize. 65 * blocksize.
65 */ 66 */
66 67
67 /* dio_state only used in the submission path 68 /* dio_state only used in the submission path */
68 69
69 struct dio_submit { 70 struct dio_submit {
70 struct bio *bio; /* bio 71 struct bio *bio; /* bio under assembly */
71 unsigned blkbits; /* doe 72 unsigned blkbits; /* doesn't change */
72 unsigned blkfactor; /* Whe 73 unsigned blkfactor; /* When we're using an alignment which
73 is 74 is finer than the filesystem's soft
74 blo 75 blocksize, this specifies how much
75 fin 76 finer. blkfactor=2 means 1/4-block
76 ali 77 alignment. Does not change */
77 unsigned start_zero_done; /* fla 78 unsigned start_zero_done; /* flag: sub-blocksize zeroing has
78 bee 79 been performed at the start of a
79 wri 80 write */
80 int pages_in_io; /* app 81 int pages_in_io; /* approximate total IO pages */
81 sector_t block_in_file; /* Cur 82 sector_t block_in_file; /* Current offset into the underlying
82 fil 83 file in dio_block units. */
83 unsigned blocks_available; /* At 84 unsigned blocks_available; /* At block_in_file. changes */
84 int reap_counter; /* rat 85 int reap_counter; /* rate limit reaping */
85 sector_t final_block_in_request;/* doe 86 sector_t final_block_in_request;/* doesn't change */
86 int boundary; /* pre 87 int boundary; /* prev block is at a boundary */
87 get_block_t *get_block; /* blo 88 get_block_t *get_block; /* block mapping function */
>> 89 dio_submit_t *submit_io; /* IO submition function */
88 90
89 loff_t logical_offset_in_bio; /* cur 91 loff_t logical_offset_in_bio; /* current first logical block in bio */
90 sector_t final_block_in_bio; /* cur 92 sector_t final_block_in_bio; /* current final block in bio + 1 */
91 sector_t next_block_for_io; /* nex 93 sector_t next_block_for_io; /* next block to be put under IO,
92 in 94 in dio_blocks units */
93 95
94 /* 96 /*
95 * Deferred addition of a page to the 97 * Deferred addition of a page to the dio. These variables are
96 * private to dio_send_cur_page(), sub 98 * private to dio_send_cur_page(), submit_page_section() and
97 * dio_bio_add_page(). 99 * dio_bio_add_page().
98 */ 100 */
99 struct page *cur_page; /* The 101 struct page *cur_page; /* The page */
100 unsigned cur_page_offset; /* Off 102 unsigned cur_page_offset; /* Offset into it, in bytes */
101 unsigned cur_page_len; /* Nr 103 unsigned cur_page_len; /* Nr of bytes at cur_page_offset */
102 sector_t cur_page_block; /* Whe 104 sector_t cur_page_block; /* Where it starts */
103 loff_t cur_page_fs_offset; /* Off 105 loff_t cur_page_fs_offset; /* Offset in file */
104 106
105 struct iov_iter *iter; 107 struct iov_iter *iter;
106 /* 108 /*
107 * Page queue. These variables belong 109 * Page queue. These variables belong to dio_refill_pages() and
108 * dio_get_page(). 110 * dio_get_page().
109 */ 111 */
110 unsigned head; /* nex 112 unsigned head; /* next page to process */
111 unsigned tail; /* las 113 unsigned tail; /* last valid page + 1 */
112 size_t from, to; 114 size_t from, to;
113 }; 115 };
114 116
115 /* dio_state communicated between submission p 117 /* dio_state communicated between submission path and end_io */
116 struct dio { 118 struct dio {
117 int flags; /* doe 119 int flags; /* doesn't change */
118 blk_opf_t opf; /* req 120 blk_opf_t opf; /* request operation type and flags */
119 struct gendisk *bio_disk; 121 struct gendisk *bio_disk;
120 struct inode *inode; 122 struct inode *inode;
121 loff_t i_size; /* i_s 123 loff_t i_size; /* i_size when submitted */
122 dio_iodone_t *end_io; /* IO 124 dio_iodone_t *end_io; /* IO completion function */
123 bool is_pinned; /* T i <<
124 125
125 void *private; /* cop 126 void *private; /* copy from map_bh.b_private */
126 127
127 /* BIO completion state */ 128 /* BIO completion state */
128 spinlock_t bio_lock; /* pro 129 spinlock_t bio_lock; /* protects BIO fields below */
129 int page_errors; /* err !! 130 int page_errors; /* errno from get_user_pages() */
130 int is_async; /* is 131 int is_async; /* is IO async ? */
131 bool defer_completion; /* def 132 bool defer_completion; /* defer AIO completion to workqueue? */
132 bool should_dirty; /* if 133 bool should_dirty; /* if pages should be dirtied */
133 int io_error; /* IO 134 int io_error; /* IO error in completion path */
134 unsigned long refcount; /* dir 135 unsigned long refcount; /* direct_io_worker() and bios */
135 struct bio *bio_list; /* sin 136 struct bio *bio_list; /* singly linked via bi_private */
136 struct task_struct *waiter; /* wai 137 struct task_struct *waiter; /* waiting task (NULL if none) */
137 138
138 /* AIO related stuff */ 139 /* AIO related stuff */
139 struct kiocb *iocb; /* kio 140 struct kiocb *iocb; /* kiocb */
140 ssize_t result; /* IO 141 ssize_t result; /* IO result */
141 142
142 /* 143 /*
143 * pages[] (and any fields placed afte 144 * pages[] (and any fields placed after it) are not zeroed out at
144 * allocation time. Don't add new fie 145 * allocation time. Don't add new fields after pages[] unless you
145 * wish that they not be zeroed. 146 * wish that they not be zeroed.
146 */ 147 */
147 union { 148 union {
148 struct page *pages[DIO_PAGES]; 149 struct page *pages[DIO_PAGES]; /* page buffer */
149 struct work_struct complete_wo 150 struct work_struct complete_work;/* deferred AIO completion */
150 }; 151 };
151 } ____cacheline_aligned_in_smp; 152 } ____cacheline_aligned_in_smp;
152 153
153 static struct kmem_cache *dio_cache __ro_after !! 154 static struct kmem_cache *dio_cache __read_mostly;
154 155
155 /* 156 /*
156 * How many pages are in the queue? 157 * How many pages are in the queue?
157 */ 158 */
158 static inline unsigned dio_pages_present(struc 159 static inline unsigned dio_pages_present(struct dio_submit *sdio)
159 { 160 {
160 return sdio->tail - sdio->head; 161 return sdio->tail - sdio->head;
161 } 162 }
162 163
163 /* 164 /*
164 * Go grab and pin some userspace pages. Typ 165 * Go grab and pin some userspace pages. Typically we'll get 64 at a time.
165 */ 166 */
166 static inline int dio_refill_pages(struct dio 167 static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio)
167 { 168 {
168 struct page **pages = dio->pages; <<
169 const enum req_op dio_op = dio->opf & 169 const enum req_op dio_op = dio->opf & REQ_OP_MASK;
170 ssize_t ret; 170 ssize_t ret;
171 171
172 ret = iov_iter_extract_pages(sdio->ite !! 172 ret = iov_iter_get_pages2(sdio->iter, dio->pages, LONG_MAX, DIO_PAGES,
173 DIO_PAGES !! 173 &sdio->from);
174 174
175 if (ret < 0 && sdio->blocks_available 175 if (ret < 0 && sdio->blocks_available && dio_op == REQ_OP_WRITE) {
>> 176 struct page *page = ZERO_PAGE(0);
176 /* 177 /*
177 * A memory fault, but the fil 178 * A memory fault, but the filesystem has some outstanding
178 * mapped blocks. We need to 179 * mapped blocks. We need to use those blocks up to avoid
179 * leaking stale data in the f 180 * leaking stale data in the file.
180 */ 181 */
181 if (dio->page_errors == 0) 182 if (dio->page_errors == 0)
182 dio->page_errors = ret 183 dio->page_errors = ret;
183 dio->pages[0] = ZERO_PAGE(0); !! 184 get_page(page);
>> 185 dio->pages[0] = page;
184 sdio->head = 0; 186 sdio->head = 0;
185 sdio->tail = 1; 187 sdio->tail = 1;
186 sdio->from = 0; 188 sdio->from = 0;
187 sdio->to = PAGE_SIZE; 189 sdio->to = PAGE_SIZE;
188 return 0; 190 return 0;
189 } 191 }
190 192
191 if (ret >= 0) { 193 if (ret >= 0) {
192 ret += sdio->from; 194 ret += sdio->from;
193 sdio->head = 0; 195 sdio->head = 0;
194 sdio->tail = (ret + PAGE_SIZE 196 sdio->tail = (ret + PAGE_SIZE - 1) / PAGE_SIZE;
195 sdio->to = ((ret - 1) & (PAGE_ 197 sdio->to = ((ret - 1) & (PAGE_SIZE - 1)) + 1;
196 return 0; 198 return 0;
197 } 199 }
198 return ret; 200 return ret;
199 } 201 }
200 202
201 /* 203 /*
202 * Get another userspace page. Returns an ERR 204 * Get another userspace page. Returns an ERR_PTR on error. Pages are
203 * buffered inside the dio so that we can call !! 205 * buffered inside the dio so that we can call get_user_pages() against a
204 * against a decent number of pages, less freq !! 206 * decent number of pages, less frequently. To provide nicer use of the
205 * the L1 cache. !! 207 * L1 cache.
206 */ 208 */
207 static inline struct page *dio_get_page(struct 209 static inline struct page *dio_get_page(struct dio *dio,
208 struct 210 struct dio_submit *sdio)
209 { 211 {
210 if (dio_pages_present(sdio) == 0) { 212 if (dio_pages_present(sdio) == 0) {
211 int ret; 213 int ret;
212 214
213 ret = dio_refill_pages(dio, sd 215 ret = dio_refill_pages(dio, sdio);
214 if (ret) 216 if (ret)
215 return ERR_PTR(ret); 217 return ERR_PTR(ret);
216 BUG_ON(dio_pages_present(sdio) 218 BUG_ON(dio_pages_present(sdio) == 0);
217 } 219 }
218 return dio->pages[sdio->head]; 220 return dio->pages[sdio->head];
219 } 221 }
220 222
221 static void dio_pin_page(struct dio *dio, stru <<
222 { <<
223 if (dio->is_pinned) <<
224 folio_add_pin(page_folio(page) <<
225 } <<
226 <<
227 static void dio_unpin_page(struct dio *dio, st <<
228 { <<
229 if (dio->is_pinned) <<
230 unpin_user_page(page); <<
231 } <<
232 <<
233 /* 223 /*
234 * dio_complete() - called when all DIO BIO I/ 224 * dio_complete() - called when all DIO BIO I/O has been completed
235 * 225 *
236 * This drops i_dio_count, lets interested par 226 * This drops i_dio_count, lets interested parties know that a DIO operation
237 * has completed, and calculates the resulting 227 * has completed, and calculates the resulting return code for the operation.
238 * 228 *
239 * It lets the filesystem know if it registere 229 * It lets the filesystem know if it registered an interest earlier via
240 * get_block. Pass the private field of the m 230 * get_block. Pass the private field of the map buffer_head so that
241 * filesystems can use it to hold additional s 231 * filesystems can use it to hold additional state between get_block calls and
242 * dio_complete. 232 * dio_complete.
243 */ 233 */
244 static ssize_t dio_complete(struct dio *dio, s 234 static ssize_t dio_complete(struct dio *dio, ssize_t ret, unsigned int flags)
245 { 235 {
246 const enum req_op dio_op = dio->opf & 236 const enum req_op dio_op = dio->opf & REQ_OP_MASK;
247 loff_t offset = dio->iocb->ki_pos; 237 loff_t offset = dio->iocb->ki_pos;
248 ssize_t transferred = 0; 238 ssize_t transferred = 0;
249 int err; 239 int err;
250 240
251 /* 241 /*
252 * AIO submission can race with bio co 242 * AIO submission can race with bio completion to get here while
253 * expecting to have the last io compl 243 * expecting to have the last io completed by bio completion.
254 * In that case -EIOCBQUEUED is in fac 244 * In that case -EIOCBQUEUED is in fact not an error we want
255 * to preserve through this call. 245 * to preserve through this call.
256 */ 246 */
257 if (ret == -EIOCBQUEUED) 247 if (ret == -EIOCBQUEUED)
258 ret = 0; 248 ret = 0;
259 249
260 if (dio->result) { 250 if (dio->result) {
261 transferred = dio->result; 251 transferred = dio->result;
262 252
263 /* Check for short read case * 253 /* Check for short read case */
264 if (dio_op == REQ_OP_READ && 254 if (dio_op == REQ_OP_READ &&
265 ((offset + transferred) > 255 ((offset + transferred) > dio->i_size))
266 transferred = dio->i_s 256 transferred = dio->i_size - offset;
267 /* ignore EFAULT if some IO ha 257 /* ignore EFAULT if some IO has been done */
268 if (unlikely(ret == -EFAULT) & 258 if (unlikely(ret == -EFAULT) && transferred)
269 ret = 0; 259 ret = 0;
270 } 260 }
271 261
272 if (ret == 0) 262 if (ret == 0)
273 ret = dio->page_errors; 263 ret = dio->page_errors;
274 if (ret == 0) 264 if (ret == 0)
275 ret = dio->io_error; 265 ret = dio->io_error;
276 if (ret == 0) 266 if (ret == 0)
277 ret = transferred; 267 ret = transferred;
278 268
279 if (dio->end_io) { 269 if (dio->end_io) {
280 // XXX: ki_pos?? 270 // XXX: ki_pos??
281 err = dio->end_io(dio->iocb, o 271 err = dio->end_io(dio->iocb, offset, ret, dio->private);
282 if (err) 272 if (err)
283 ret = err; 273 ret = err;
284 } 274 }
285 275
286 /* 276 /*
287 * Try again to invalidate clean pages 277 * Try again to invalidate clean pages which might have been cached by
288 * non-direct readahead, or faulted in 278 * non-direct readahead, or faulted in by get_user_pages() if the source
289 * of the write was an mmap'ed region 279 * of the write was an mmap'ed region of the file we're writing. Either
290 * one is a pretty crazy thing to do, 280 * one is a pretty crazy thing to do, so we don't support it 100%. If
291 * this invalidation fails, tough, the 281 * this invalidation fails, tough, the write still worked...
292 * 282 *
293 * And this page cache invalidation ha 283 * And this page cache invalidation has to be after dio->end_io(), as
294 * some filesystems convert unwritten 284 * some filesystems convert unwritten extents to real allocations in
295 * end_io() when necessary, otherwise 285 * end_io() when necessary, otherwise a racing buffer read would cache
296 * zeros from unwritten extents. 286 * zeros from unwritten extents.
297 */ 287 */
298 if (flags & DIO_COMPLETE_INVALIDATE && 288 if (flags & DIO_COMPLETE_INVALIDATE &&
299 ret > 0 && dio_op == REQ_OP_WRITE) !! 289 ret > 0 && dio_op == REQ_OP_WRITE &&
300 kiocb_invalidate_post_direct_w !! 290 dio->inode->i_mapping->nrpages) {
>> 291 err = invalidate_inode_pages2_range(dio->inode->i_mapping,
>> 292 offset >> PAGE_SHIFT,
>> 293 (offset + ret - 1) >> PAGE_SHIFT);
>> 294 if (err)
>> 295 dio_warn_stale_pagecache(dio->iocb->ki_filp);
>> 296 }
301 297
302 inode_dio_end(dio->inode); 298 inode_dio_end(dio->inode);
303 299
304 if (flags & DIO_COMPLETE_ASYNC) { 300 if (flags & DIO_COMPLETE_ASYNC) {
305 /* 301 /*
306 * generic_write_sync expects 302 * generic_write_sync expects ki_pos to have been updated
307 * already, but the submission 303 * already, but the submission path only does this for
308 * synchronous I/O. 304 * synchronous I/O.
309 */ 305 */
310 dio->iocb->ki_pos += transferr 306 dio->iocb->ki_pos += transferred;
311 307
312 if (ret > 0 && dio_op == REQ_O 308 if (ret > 0 && dio_op == REQ_OP_WRITE)
313 ret = generic_write_sy 309 ret = generic_write_sync(dio->iocb, ret);
314 dio->iocb->ki_complete(dio->io 310 dio->iocb->ki_complete(dio->iocb, ret);
315 } 311 }
316 312
317 kmem_cache_free(dio_cache, dio); 313 kmem_cache_free(dio_cache, dio);
318 return ret; 314 return ret;
319 } 315 }
320 316
321 static void dio_aio_complete_work(struct work_ 317 static void dio_aio_complete_work(struct work_struct *work)
322 { 318 {
323 struct dio *dio = container_of(work, s 319 struct dio *dio = container_of(work, struct dio, complete_work);
324 320
325 dio_complete(dio, 0, DIO_COMPLETE_ASYN 321 dio_complete(dio, 0, DIO_COMPLETE_ASYNC | DIO_COMPLETE_INVALIDATE);
326 } 322 }
327 323
328 static blk_status_t dio_bio_complete(struct di 324 static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio);
329 325
330 /* 326 /*
331 * Asynchronous IO callback. 327 * Asynchronous IO callback.
332 */ 328 */
333 static void dio_bio_end_aio(struct bio *bio) 329 static void dio_bio_end_aio(struct bio *bio)
334 { 330 {
335 struct dio *dio = bio->bi_private; 331 struct dio *dio = bio->bi_private;
336 const enum req_op dio_op = dio->opf & 332 const enum req_op dio_op = dio->opf & REQ_OP_MASK;
337 unsigned long remaining; 333 unsigned long remaining;
338 unsigned long flags; 334 unsigned long flags;
339 bool defer_completion = false; 335 bool defer_completion = false;
340 336
341 /* cleanup the bio */ 337 /* cleanup the bio */
342 dio_bio_complete(dio, bio); 338 dio_bio_complete(dio, bio);
343 339
344 spin_lock_irqsave(&dio->bio_lock, flag 340 spin_lock_irqsave(&dio->bio_lock, flags);
345 remaining = --dio->refcount; 341 remaining = --dio->refcount;
346 if (remaining == 1 && dio->waiter) 342 if (remaining == 1 && dio->waiter)
347 wake_up_process(dio->waiter); 343 wake_up_process(dio->waiter);
348 spin_unlock_irqrestore(&dio->bio_lock, 344 spin_unlock_irqrestore(&dio->bio_lock, flags);
349 345
350 if (remaining == 0) { 346 if (remaining == 0) {
351 /* 347 /*
352 * Defer completion when defer 348 * Defer completion when defer_completion is set or
353 * when the inode has pages ma 349 * when the inode has pages mapped and this is AIO write.
354 * We need to invalidate those 350 * We need to invalidate those pages because there is a
355 * chance they contain stale d 351 * chance they contain stale data in the case buffered IO
356 * went in between AIO submiss 352 * went in between AIO submission and completion into the
357 * same region. 353 * same region.
358 */ 354 */
359 if (dio->result) 355 if (dio->result)
360 defer_completion = dio 356 defer_completion = dio->defer_completion ||
361 (di 357 (dio_op == REQ_OP_WRITE &&
362 di 358 dio->inode->i_mapping->nrpages);
363 if (defer_completion) { 359 if (defer_completion) {
364 INIT_WORK(&dio->comple 360 INIT_WORK(&dio->complete_work, dio_aio_complete_work);
365 queue_work(dio->inode- 361 queue_work(dio->inode->i_sb->s_dio_done_wq,
366 &dio->compl 362 &dio->complete_work);
367 } else { 363 } else {
368 dio_complete(dio, 0, D 364 dio_complete(dio, 0, DIO_COMPLETE_ASYNC);
369 } 365 }
370 } 366 }
371 } 367 }
372 368
373 /* 369 /*
374 * The BIO completion handler simply queues th 370 * The BIO completion handler simply queues the BIO up for the process-context
375 * handler. 371 * handler.
376 * 372 *
377 * During I/O bi_private points at the dio. A 373 * During I/O bi_private points at the dio. After I/O, bi_private is used to
378 * implement a singly-linked list of completed 374 * implement a singly-linked list of completed BIOs, at dio->bio_list.
379 */ 375 */
380 static void dio_bio_end_io(struct bio *bio) 376 static void dio_bio_end_io(struct bio *bio)
381 { 377 {
382 struct dio *dio = bio->bi_private; 378 struct dio *dio = bio->bi_private;
383 unsigned long flags; 379 unsigned long flags;
384 380
385 spin_lock_irqsave(&dio->bio_lock, flag 381 spin_lock_irqsave(&dio->bio_lock, flags);
386 bio->bi_private = dio->bio_list; 382 bio->bi_private = dio->bio_list;
387 dio->bio_list = bio; 383 dio->bio_list = bio;
388 if (--dio->refcount == 1 && dio->waite 384 if (--dio->refcount == 1 && dio->waiter)
389 wake_up_process(dio->waiter); 385 wake_up_process(dio->waiter);
390 spin_unlock_irqrestore(&dio->bio_lock, 386 spin_unlock_irqrestore(&dio->bio_lock, flags);
391 } 387 }
392 388
393 static inline void 389 static inline void
394 dio_bio_alloc(struct dio *dio, struct dio_subm 390 dio_bio_alloc(struct dio *dio, struct dio_submit *sdio,
395 struct block_device *bdev, 391 struct block_device *bdev,
396 sector_t first_sector, int nr_ve 392 sector_t first_sector, int nr_vecs)
397 { 393 {
398 struct bio *bio; 394 struct bio *bio;
399 395
400 /* 396 /*
401 * bio_alloc() is guaranteed to return 397 * bio_alloc() is guaranteed to return a bio when allowed to sleep and
402 * we request a valid number of vector 398 * we request a valid number of vectors.
403 */ 399 */
404 bio = bio_alloc(bdev, nr_vecs, dio->op 400 bio = bio_alloc(bdev, nr_vecs, dio->opf, GFP_KERNEL);
405 bio->bi_iter.bi_sector = first_sector; 401 bio->bi_iter.bi_sector = first_sector;
406 if (dio->is_async) 402 if (dio->is_async)
407 bio->bi_end_io = dio_bio_end_a 403 bio->bi_end_io = dio_bio_end_aio;
408 else 404 else
409 bio->bi_end_io = dio_bio_end_i 405 bio->bi_end_io = dio_bio_end_io;
410 if (dio->is_pinned) <<
411 bio_set_flag(bio, BIO_PAGE_PIN <<
412 bio->bi_write_hint = file_inode(dio->i <<
413 <<
414 sdio->bio = bio; 406 sdio->bio = bio;
415 sdio->logical_offset_in_bio = sdio->cu 407 sdio->logical_offset_in_bio = sdio->cur_page_fs_offset;
416 } 408 }
417 409
418 /* 410 /*
419 * In the AIO read case we speculatively dirty 411 * In the AIO read case we speculatively dirty the pages before starting IO.
420 * During IO completion, any of these pages wh 412 * During IO completion, any of these pages which happen to have been written
421 * back will be redirtied by bio_check_pages_d 413 * back will be redirtied by bio_check_pages_dirty().
422 * 414 *
423 * bios hold a dio reference between submit_bi 415 * bios hold a dio reference between submit_bio and ->end_io.
424 */ 416 */
425 static inline void dio_bio_submit(struct dio * 417 static inline void dio_bio_submit(struct dio *dio, struct dio_submit *sdio)
426 { 418 {
427 const enum req_op dio_op = dio->opf & 419 const enum req_op dio_op = dio->opf & REQ_OP_MASK;
428 struct bio *bio = sdio->bio; 420 struct bio *bio = sdio->bio;
429 unsigned long flags; 421 unsigned long flags;
430 422
431 bio->bi_private = dio; 423 bio->bi_private = dio;
>> 424 /* don't account direct I/O as memory stall */
>> 425 bio_clear_flag(bio, BIO_WORKINGSET);
432 426
433 spin_lock_irqsave(&dio->bio_lock, flag 427 spin_lock_irqsave(&dio->bio_lock, flags);
434 dio->refcount++; 428 dio->refcount++;
435 spin_unlock_irqrestore(&dio->bio_lock, 429 spin_unlock_irqrestore(&dio->bio_lock, flags);
436 430
437 if (dio->is_async && dio_op == REQ_OP_ 431 if (dio->is_async && dio_op == REQ_OP_READ && dio->should_dirty)
438 bio_set_pages_dirty(bio); 432 bio_set_pages_dirty(bio);
439 433
440 dio->bio_disk = bio->bi_bdev->bd_disk; 434 dio->bio_disk = bio->bi_bdev->bd_disk;
441 435
442 submit_bio(bio); !! 436 if (sdio->submit_io)
>> 437 sdio->submit_io(bio, dio->inode, sdio->logical_offset_in_bio);
>> 438 else
>> 439 submit_bio(bio);
443 440
444 sdio->bio = NULL; 441 sdio->bio = NULL;
445 sdio->boundary = 0; 442 sdio->boundary = 0;
446 sdio->logical_offset_in_bio = 0; 443 sdio->logical_offset_in_bio = 0;
447 } 444 }
448 445
449 /* 446 /*
450 * Release any resources in case of a failure 447 * Release any resources in case of a failure
451 */ 448 */
452 static inline void dio_cleanup(struct dio *dio 449 static inline void dio_cleanup(struct dio *dio, struct dio_submit *sdio)
453 { 450 {
454 if (dio->is_pinned) !! 451 while (sdio->head < sdio->tail)
455 unpin_user_pages(dio->pages + !! 452 put_page(dio->pages[sdio->head++]);
456 sdio->tail - <<
457 sdio->head = sdio->tail; <<
458 } 453 }
459 454
460 /* 455 /*
461 * Wait for the next BIO to complete. Remove 456 * Wait for the next BIO to complete. Remove it and return it. NULL is
462 * returned once all BIOs have been completed. 457 * returned once all BIOs have been completed. This must only be called once
463 * all bios have been issued so that dio->refc 458 * all bios have been issued so that dio->refcount can only decrease. This
464 * requires that the caller hold a reference o 459 * requires that the caller hold a reference on the dio.
465 */ 460 */
466 static struct bio *dio_await_one(struct dio *d 461 static struct bio *dio_await_one(struct dio *dio)
467 { 462 {
468 unsigned long flags; 463 unsigned long flags;
469 struct bio *bio = NULL; 464 struct bio *bio = NULL;
470 465
471 spin_lock_irqsave(&dio->bio_lock, flag 466 spin_lock_irqsave(&dio->bio_lock, flags);
472 467
473 /* 468 /*
474 * Wait as long as the list is empty a 469 * Wait as long as the list is empty and there are bios in flight. bio
475 * completion drops the count, maybe a 470 * completion drops the count, maybe adds to the list, and wakes while
476 * holding the bio_lock so we don't ne 471 * holding the bio_lock so we don't need set_current_state()'s barrier
477 * and can call it after testing our c 472 * and can call it after testing our condition.
478 */ 473 */
479 while (dio->refcount > 1 && dio->bio_l 474 while (dio->refcount > 1 && dio->bio_list == NULL) {
480 __set_current_state(TASK_UNINT 475 __set_current_state(TASK_UNINTERRUPTIBLE);
481 dio->waiter = current; 476 dio->waiter = current;
482 spin_unlock_irqrestore(&dio->b 477 spin_unlock_irqrestore(&dio->bio_lock, flags);
483 blk_io_schedule(); 478 blk_io_schedule();
484 /* wake up sets us TASK_RUNNIN 479 /* wake up sets us TASK_RUNNING */
485 spin_lock_irqsave(&dio->bio_lo 480 spin_lock_irqsave(&dio->bio_lock, flags);
486 dio->waiter = NULL; 481 dio->waiter = NULL;
487 } 482 }
488 if (dio->bio_list) { 483 if (dio->bio_list) {
489 bio = dio->bio_list; 484 bio = dio->bio_list;
490 dio->bio_list = bio->bi_privat 485 dio->bio_list = bio->bi_private;
491 } 486 }
492 spin_unlock_irqrestore(&dio->bio_lock, 487 spin_unlock_irqrestore(&dio->bio_lock, flags);
493 return bio; 488 return bio;
494 } 489 }
495 490
496 /* 491 /*
497 * Process one completed BIO. No locks are he 492 * Process one completed BIO. No locks are held.
498 */ 493 */
499 static blk_status_t dio_bio_complete(struct di 494 static blk_status_t dio_bio_complete(struct dio *dio, struct bio *bio)
500 { 495 {
501 blk_status_t err = bio->bi_status; 496 blk_status_t err = bio->bi_status;
502 const enum req_op dio_op = dio->opf & 497 const enum req_op dio_op = dio->opf & REQ_OP_MASK;
503 bool should_dirty = dio_op == REQ_OP_R 498 bool should_dirty = dio_op == REQ_OP_READ && dio->should_dirty;
504 499
505 if (err) { 500 if (err) {
506 if (err == BLK_STS_AGAIN && (b 501 if (err == BLK_STS_AGAIN && (bio->bi_opf & REQ_NOWAIT))
507 dio->io_error = -EAGAI 502 dio->io_error = -EAGAIN;
508 else 503 else
509 dio->io_error = -EIO; 504 dio->io_error = -EIO;
510 } 505 }
511 506
512 if (dio->is_async && should_dirty) { 507 if (dio->is_async && should_dirty) {
513 bio_check_pages_dirty(bio); 508 bio_check_pages_dirty(bio); /* transfers ownership */
514 } else { 509 } else {
515 bio_release_pages(bio, should_ 510 bio_release_pages(bio, should_dirty);
516 bio_put(bio); 511 bio_put(bio);
517 } 512 }
518 return err; 513 return err;
519 } 514 }
520 515
521 /* 516 /*
522 * Wait on and process all in-flight BIOs. Th 517 * Wait on and process all in-flight BIOs. This must only be called once
523 * all bios have been issued so that the refco 518 * all bios have been issued so that the refcount can only decrease.
524 * This just waits for all bios to make it thr 519 * This just waits for all bios to make it through dio_bio_complete. IO
525 * errors are propagated through dio->io_error 520 * errors are propagated through dio->io_error and should be propagated via
526 * dio_complete(). 521 * dio_complete().
527 */ 522 */
528 static void dio_await_completion(struct dio *d 523 static void dio_await_completion(struct dio *dio)
529 { 524 {
530 struct bio *bio; 525 struct bio *bio;
531 do { 526 do {
532 bio = dio_await_one(dio); 527 bio = dio_await_one(dio);
533 if (bio) 528 if (bio)
534 dio_bio_complete(dio, 529 dio_bio_complete(dio, bio);
535 } while (bio); 530 } while (bio);
536 } 531 }
537 532
538 /* 533 /*
539 * A really large O_DIRECT read or write can g 534 * A really large O_DIRECT read or write can generate a lot of BIOs. So
540 * to keep the memory consumption sane we peri 535 * to keep the memory consumption sane we periodically reap any completed BIOs
541 * during the BIO generation phase. 536 * during the BIO generation phase.
542 * 537 *
543 * This also helps to limit the peak amount of 538 * This also helps to limit the peak amount of pinned userspace memory.
544 */ 539 */
545 static inline int dio_bio_reap(struct dio *dio 540 static inline int dio_bio_reap(struct dio *dio, struct dio_submit *sdio)
546 { 541 {
547 int ret = 0; 542 int ret = 0;
548 543
549 if (sdio->reap_counter++ >= 64) { 544 if (sdio->reap_counter++ >= 64) {
550 while (dio->bio_list) { 545 while (dio->bio_list) {
551 unsigned long flags; 546 unsigned long flags;
552 struct bio *bio; 547 struct bio *bio;
553 int ret2; 548 int ret2;
554 549
555 spin_lock_irqsave(&dio 550 spin_lock_irqsave(&dio->bio_lock, flags);
556 bio = dio->bio_list; 551 bio = dio->bio_list;
557 dio->bio_list = bio->b 552 dio->bio_list = bio->bi_private;
558 spin_unlock_irqrestore 553 spin_unlock_irqrestore(&dio->bio_lock, flags);
559 ret2 = blk_status_to_e 554 ret2 = blk_status_to_errno(dio_bio_complete(dio, bio));
560 if (ret == 0) 555 if (ret == 0)
561 ret = ret2; 556 ret = ret2;
562 } 557 }
563 sdio->reap_counter = 0; 558 sdio->reap_counter = 0;
564 } 559 }
565 return ret; 560 return ret;
566 } 561 }
567 562
>> 563 /*
>> 564 * Create workqueue for deferred direct IO completions. We allocate the
>> 565 * workqueue when it's first needed. This avoids creating workqueue for
>> 566 * filesystems that don't need it and also allows us to create the workqueue
>> 567 * late enough so the we can include s_id in the name of the workqueue.
>> 568 */
>> 569 int sb_init_dio_done_wq(struct super_block *sb)
>> 570 {
>> 571 struct workqueue_struct *old;
>> 572 struct workqueue_struct *wq = alloc_workqueue("dio/%s",
>> 573 WQ_MEM_RECLAIM, 0,
>> 574 sb->s_id);
>> 575 if (!wq)
>> 576 return -ENOMEM;
>> 577 /*
>> 578 * This has to be atomic as more DIOs can race to create the workqueue
>> 579 */
>> 580 old = cmpxchg(&sb->s_dio_done_wq, NULL, wq);
>> 581 /* Someone created workqueue before us? Free ours... */
>> 582 if (old)
>> 583 destroy_workqueue(wq);
>> 584 return 0;
>> 585 }
>> 586
568 static int dio_set_defer_completion(struct dio 587 static int dio_set_defer_completion(struct dio *dio)
569 { 588 {
570 struct super_block *sb = dio->inode->i 589 struct super_block *sb = dio->inode->i_sb;
571 590
572 if (dio->defer_completion) 591 if (dio->defer_completion)
573 return 0; 592 return 0;
574 dio->defer_completion = true; 593 dio->defer_completion = true;
575 if (!sb->s_dio_done_wq) 594 if (!sb->s_dio_done_wq)
576 return sb_init_dio_done_wq(sb) 595 return sb_init_dio_done_wq(sb);
577 return 0; 596 return 0;
578 } 597 }
579 598
580 /* 599 /*
581 * Call into the fs to map some more disk bloc 600 * Call into the fs to map some more disk blocks. We record the current number
582 * of available blocks at sdio->blocks_availab 601 * of available blocks at sdio->blocks_available. These are in units of the
583 * fs blocksize, i_blocksize(inode). 602 * fs blocksize, i_blocksize(inode).
584 * 603 *
585 * The fs is allowed to map lots of blocks at 604 * The fs is allowed to map lots of blocks at once. If it wants to do that,
586 * it uses the passed inode-relative block num 605 * it uses the passed inode-relative block number as the file offset, as usual.
587 * 606 *
588 * get_block() is passed the number of i_blkbi 607 * get_block() is passed the number of i_blkbits-sized blocks which direct_io
589 * has remaining to do. The fs should not map 608 * has remaining to do. The fs should not map more than this number of blocks.
590 * 609 *
591 * If the fs has mapped a lot of blocks, it sh 610 * If the fs has mapped a lot of blocks, it should populate bh->b_size to
592 * indicate how much contiguous disk space has 611 * indicate how much contiguous disk space has been made available at
593 * bh->b_blocknr. 612 * bh->b_blocknr.
594 * 613 *
595 * If *any* of the mapped blocks are new, then 614 * If *any* of the mapped blocks are new, then the fs must set buffer_new().
596 * This isn't very efficient... 615 * This isn't very efficient...
597 * 616 *
598 * In the case of filesystem holes: the fs may 617 * In the case of filesystem holes: the fs may return an arbitrarily-large
599 * hole by returning an appropriate value in b 618 * hole by returning an appropriate value in b_size and by clearing
600 * buffer_mapped(). However the direct-io cod 619 * buffer_mapped(). However the direct-io code will only process holes one
601 * block at a time - it will repeatedly call g 620 * block at a time - it will repeatedly call get_block() as it walks the hole.
602 */ 621 */
603 static int get_more_blocks(struct dio *dio, st 622 static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
604 struct buffer_head 623 struct buffer_head *map_bh)
605 { 624 {
606 const enum req_op dio_op = dio->opf & 625 const enum req_op dio_op = dio->opf & REQ_OP_MASK;
607 int ret; 626 int ret;
608 sector_t fs_startblk; /* Into file, 627 sector_t fs_startblk; /* Into file, in filesystem-sized blocks */
609 sector_t fs_endblk; /* Into file, 628 sector_t fs_endblk; /* Into file, in filesystem-sized blocks */
610 unsigned long fs_count; /* Number of f 629 unsigned long fs_count; /* Number of filesystem-sized blocks */
611 int create; 630 int create;
612 unsigned int i_blkbits = sdio->blkbits 631 unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor;
613 loff_t i_size; 632 loff_t i_size;
614 633
615 /* 634 /*
616 * If there was a memory error and we' 635 * If there was a memory error and we've overwritten all the
617 * mapped blocks then we can now retur 636 * mapped blocks then we can now return that memory error
618 */ 637 */
619 ret = dio->page_errors; 638 ret = dio->page_errors;
620 if (ret == 0) { 639 if (ret == 0) {
621 BUG_ON(sdio->block_in_file >= 640 BUG_ON(sdio->block_in_file >= sdio->final_block_in_request);
622 fs_startblk = sdio->block_in_f 641 fs_startblk = sdio->block_in_file >> sdio->blkfactor;
623 fs_endblk = (sdio->final_block 642 fs_endblk = (sdio->final_block_in_request - 1) >>
624 sdio-> 643 sdio->blkfactor;
625 fs_count = fs_endblk - fs_star 644 fs_count = fs_endblk - fs_startblk + 1;
626 645
627 map_bh->b_state = 0; 646 map_bh->b_state = 0;
628 map_bh->b_size = fs_count << i 647 map_bh->b_size = fs_count << i_blkbits;
629 648
630 /* 649 /*
631 * For writes that could fill 650 * For writes that could fill holes inside i_size on a
632 * DIO_SKIP_HOLES filesystem w 651 * DIO_SKIP_HOLES filesystem we forbid block creations: only
633 * overwrites are permitted. W 652 * overwrites are permitted. We will return early to the caller
634 * once we see an unmapped buf 653 * once we see an unmapped buffer head returned, and the caller
635 * will fall back to buffered 654 * will fall back to buffered I/O.
636 * 655 *
637 * Otherwise the decision is l 656 * Otherwise the decision is left to the get_blocks method,
638 * which may decide to handle 657 * which may decide to handle it or also return an unmapped
639 * buffer head. 658 * buffer head.
640 */ 659 */
641 create = dio_op == REQ_OP_WRIT 660 create = dio_op == REQ_OP_WRITE;
642 if (dio->flags & DIO_SKIP_HOLE 661 if (dio->flags & DIO_SKIP_HOLES) {
643 i_size = i_size_read(d 662 i_size = i_size_read(dio->inode);
644 if (i_size && fs_start 663 if (i_size && fs_startblk <= (i_size - 1) >> i_blkbits)
645 create = 0; 664 create = 0;
646 } 665 }
647 666
648 ret = (*sdio->get_block)(dio-> 667 ret = (*sdio->get_block)(dio->inode, fs_startblk,
649 668 map_bh, create);
650 669
651 /* Store for completion */ 670 /* Store for completion */
652 dio->private = map_bh->b_priva 671 dio->private = map_bh->b_private;
653 672
654 if (ret == 0 && buffer_defer_c 673 if (ret == 0 && buffer_defer_completion(map_bh))
655 ret = dio_set_defer_co 674 ret = dio_set_defer_completion(dio);
656 } 675 }
657 return ret; 676 return ret;
658 } 677 }
659 678
660 /* 679 /*
661 * There is no bio. Make one now. 680 * There is no bio. Make one now.
662 */ 681 */
663 static inline int dio_new_bio(struct dio *dio, 682 static inline int dio_new_bio(struct dio *dio, struct dio_submit *sdio,
664 sector_t start_sector, struct 683 sector_t start_sector, struct buffer_head *map_bh)
665 { 684 {
666 sector_t sector; 685 sector_t sector;
667 int ret, nr_pages; 686 int ret, nr_pages;
668 687
669 ret = dio_bio_reap(dio, sdio); 688 ret = dio_bio_reap(dio, sdio);
670 if (ret) 689 if (ret)
671 goto out; 690 goto out;
672 sector = start_sector << (sdio->blkbit 691 sector = start_sector << (sdio->blkbits - 9);
673 nr_pages = bio_max_segs(sdio->pages_in 692 nr_pages = bio_max_segs(sdio->pages_in_io);
674 BUG_ON(nr_pages <= 0); 693 BUG_ON(nr_pages <= 0);
675 dio_bio_alloc(dio, sdio, map_bh->b_bde 694 dio_bio_alloc(dio, sdio, map_bh->b_bdev, sector, nr_pages);
676 sdio->boundary = 0; 695 sdio->boundary = 0;
677 out: 696 out:
678 return ret; 697 return ret;
679 } 698 }
680 699
681 /* 700 /*
682 * Attempt to put the current chunk of 'cur_pa 701 * Attempt to put the current chunk of 'cur_page' into the current BIO. If
683 * that was successful then update final_block 702 * that was successful then update final_block_in_bio and take a ref against
684 * the just-added page. 703 * the just-added page.
685 * 704 *
686 * Return zero on success. Non-zero means the 705 * Return zero on success. Non-zero means the caller needs to start a new BIO.
687 */ 706 */
688 static inline int dio_bio_add_page(struct dio !! 707 static inline int dio_bio_add_page(struct dio_submit *sdio)
689 { 708 {
690 int ret; 709 int ret;
691 710
692 ret = bio_add_page(sdio->bio, sdio->cu 711 ret = bio_add_page(sdio->bio, sdio->cur_page,
693 sdio->cur_page_len, sd 712 sdio->cur_page_len, sdio->cur_page_offset);
694 if (ret == sdio->cur_page_len) { 713 if (ret == sdio->cur_page_len) {
695 /* 714 /*
696 * Decrement count only, if we 715 * Decrement count only, if we are done with this page
697 */ 716 */
698 if ((sdio->cur_page_len + sdio 717 if ((sdio->cur_page_len + sdio->cur_page_offset) == PAGE_SIZE)
699 sdio->pages_in_io--; 718 sdio->pages_in_io--;
700 dio_pin_page(dio, sdio->cur_pa !! 719 get_page(sdio->cur_page);
701 sdio->final_block_in_bio = sdi 720 sdio->final_block_in_bio = sdio->cur_page_block +
702 (sdio->cur_page_len >> 721 (sdio->cur_page_len >> sdio->blkbits);
703 ret = 0; 722 ret = 0;
704 } else { 723 } else {
705 ret = 1; 724 ret = 1;
706 } 725 }
707 return ret; 726 return ret;
708 } 727 }
709 728
710 /* 729 /*
711 * Put cur_page under IO. The section of cur_ 730 * Put cur_page under IO. The section of cur_page which is described by
712 * cur_page_offset,cur_page_len is put into a 731 * cur_page_offset,cur_page_len is put into a BIO. The section of cur_page
713 * starts on-disk at cur_page_block. 732 * starts on-disk at cur_page_block.
714 * 733 *
715 * We take a ref against the page here (on beh 734 * We take a ref against the page here (on behalf of its presence in the bio).
716 * 735 *
717 * The caller of this function is responsible 736 * The caller of this function is responsible for removing cur_page from the
718 * dio, and for dropping the refcount which ca 737 * dio, and for dropping the refcount which came from that presence.
719 */ 738 */
720 static inline int dio_send_cur_page(struct dio 739 static inline int dio_send_cur_page(struct dio *dio, struct dio_submit *sdio,
721 struct buffer_head *map_bh) 740 struct buffer_head *map_bh)
722 { 741 {
723 int ret = 0; 742 int ret = 0;
724 743
725 if (sdio->bio) { 744 if (sdio->bio) {
726 loff_t cur_offset = sdio->cur_ 745 loff_t cur_offset = sdio->cur_page_fs_offset;
727 loff_t bio_next_offset = sdio- 746 loff_t bio_next_offset = sdio->logical_offset_in_bio +
728 sdio->bio->bi_iter.bi_ 747 sdio->bio->bi_iter.bi_size;
729 748
730 /* 749 /*
731 * See whether this new reques 750 * See whether this new request is contiguous with the old.
732 * 751 *
733 * Btrfs cannot handle having 752 * Btrfs cannot handle having logically non-contiguous requests
734 * submitted. For example if 753 * submitted. For example if you have
735 * 754 *
736 * Logical: [0-4095][HOLE][81 755 * Logical: [0-4095][HOLE][8192-12287]
737 * Physical: [0-4095] [40 756 * Physical: [0-4095] [4096-8191]
738 * 757 *
739 * We cannot submit those page 758 * We cannot submit those pages together as one BIO. So if our
740 * current logical offset in t 759 * current logical offset in the file does not equal what would
741 * be the next logical offset 760 * be the next logical offset in the bio, submit the bio we
742 * have. 761 * have.
743 */ 762 */
744 if (sdio->final_block_in_bio ! 763 if (sdio->final_block_in_bio != sdio->cur_page_block ||
745 cur_offset != bio_next_off 764 cur_offset != bio_next_offset)
746 dio_bio_submit(dio, sd 765 dio_bio_submit(dio, sdio);
747 } 766 }
748 767
749 if (sdio->bio == NULL) { 768 if (sdio->bio == NULL) {
750 ret = dio_new_bio(dio, sdio, s 769 ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
751 if (ret) 770 if (ret)
752 goto out; 771 goto out;
753 } 772 }
754 773
755 if (dio_bio_add_page(dio, sdio) != 0) !! 774 if (dio_bio_add_page(sdio) != 0) {
756 dio_bio_submit(dio, sdio); 775 dio_bio_submit(dio, sdio);
757 ret = dio_new_bio(dio, sdio, s 776 ret = dio_new_bio(dio, sdio, sdio->cur_page_block, map_bh);
758 if (ret == 0) { 777 if (ret == 0) {
759 ret = dio_bio_add_page !! 778 ret = dio_bio_add_page(sdio);
760 BUG_ON(ret != 0); 779 BUG_ON(ret != 0);
761 } 780 }
762 } 781 }
763 out: 782 out:
764 return ret; 783 return ret;
765 } 784 }
766 785
767 /* 786 /*
768 * An autonomous function to put a chunk of a 787 * An autonomous function to put a chunk of a page under deferred IO.
769 * 788 *
770 * The caller doesn't actually know (or care) 789 * The caller doesn't actually know (or care) whether this piece of page is in
771 * a BIO, or is under IO or whatever. We just 790 * a BIO, or is under IO or whatever. We just take care of all possible
772 * situations here. The separation between th 791 * situations here. The separation between the logic of do_direct_IO() and
773 * that of submit_page_section() is important 792 * that of submit_page_section() is important for clarity. Please don't break.
774 * 793 *
775 * The chunk of page starts on-disk at blocknr 794 * The chunk of page starts on-disk at blocknr.
776 * 795 *
777 * We perform deferred IO, by recording the la 796 * We perform deferred IO, by recording the last-submitted page inside our
778 * private part of the dio structure. If poss 797 * private part of the dio structure. If possible, we just expand the IO
779 * across that page here. 798 * across that page here.
780 * 799 *
781 * If that doesn't work out then we put the ol 800 * If that doesn't work out then we put the old page into the bio and add this
782 * page to the dio instead. 801 * page to the dio instead.
783 */ 802 */
784 static inline int 803 static inline int
785 submit_page_section(struct dio *dio, struct di 804 submit_page_section(struct dio *dio, struct dio_submit *sdio, struct page *page,
786 unsigned offset, unsigned 805 unsigned offset, unsigned len, sector_t blocknr,
787 struct buffer_head *map_bh 806 struct buffer_head *map_bh)
788 { 807 {
789 const enum req_op dio_op = dio->opf & 808 const enum req_op dio_op = dio->opf & REQ_OP_MASK;
790 int ret = 0; 809 int ret = 0;
791 int boundary = sdio->boundary; /* dio 810 int boundary = sdio->boundary; /* dio_send_cur_page may clear it */
792 811
793 if (dio_op == REQ_OP_WRITE) { 812 if (dio_op == REQ_OP_WRITE) {
794 /* 813 /*
795 * Read accounting is performe 814 * Read accounting is performed in submit_bio()
796 */ 815 */
797 task_io_account_write(len); 816 task_io_account_write(len);
798 } 817 }
799 818
800 /* 819 /*
801 * Can we just grow the current page's 820 * Can we just grow the current page's presence in the dio?
802 */ 821 */
803 if (sdio->cur_page == page && 822 if (sdio->cur_page == page &&
804 sdio->cur_page_offset + sdio->cur_ 823 sdio->cur_page_offset + sdio->cur_page_len == offset &&
805 sdio->cur_page_block + 824 sdio->cur_page_block +
806 (sdio->cur_page_len >> sdio->blkbi 825 (sdio->cur_page_len >> sdio->blkbits) == blocknr) {
807 sdio->cur_page_len += len; 826 sdio->cur_page_len += len;
808 goto out; 827 goto out;
809 } 828 }
810 829
811 /* 830 /*
812 * If there's a deferred page already 831 * If there's a deferred page already there then send it.
813 */ 832 */
814 if (sdio->cur_page) { 833 if (sdio->cur_page) {
815 ret = dio_send_cur_page(dio, s 834 ret = dio_send_cur_page(dio, sdio, map_bh);
816 dio_unpin_page(dio, sdio->cur_ !! 835 put_page(sdio->cur_page);
817 sdio->cur_page = NULL; 836 sdio->cur_page = NULL;
818 if (ret) 837 if (ret)
819 return ret; 838 return ret;
820 } 839 }
821 840
822 dio_pin_page(dio, page); !! 841 get_page(page); /* It is in dio */
823 sdio->cur_page = page; 842 sdio->cur_page = page;
824 sdio->cur_page_offset = offset; 843 sdio->cur_page_offset = offset;
825 sdio->cur_page_len = len; 844 sdio->cur_page_len = len;
826 sdio->cur_page_block = blocknr; 845 sdio->cur_page_block = blocknr;
827 sdio->cur_page_fs_offset = sdio->block 846 sdio->cur_page_fs_offset = sdio->block_in_file << sdio->blkbits;
828 out: 847 out:
829 /* 848 /*
830 * If boundary then we want to schedul 849 * If boundary then we want to schedule the IO now to
831 * avoid metadata seeks. 850 * avoid metadata seeks.
832 */ 851 */
833 if (boundary) { 852 if (boundary) {
834 ret = dio_send_cur_page(dio, s 853 ret = dio_send_cur_page(dio, sdio, map_bh);
835 if (sdio->bio) 854 if (sdio->bio)
836 dio_bio_submit(dio, sd 855 dio_bio_submit(dio, sdio);
837 dio_unpin_page(dio, sdio->cur_ !! 856 put_page(sdio->cur_page);
838 sdio->cur_page = NULL; 857 sdio->cur_page = NULL;
839 } 858 }
840 return ret; 859 return ret;
841 } 860 }
842 861
843 /* 862 /*
844 * If we are not writing the entire block and 863 * If we are not writing the entire block and get_block() allocated
845 * the block for us, we need to fill-in the un 864 * the block for us, we need to fill-in the unused portion of the
846 * block with zeros. This happens only if user 865 * block with zeros. This happens only if user-buffer, fileoffset or
847 * io length is not filesystem block-size mult 866 * io length is not filesystem block-size multiple.
848 * 867 *
849 * `end' is zero if we're doing the start of t 868 * `end' is zero if we're doing the start of the IO, 1 at the end of the
850 * IO. 869 * IO.
851 */ 870 */
852 static inline void dio_zero_block(struct dio * 871 static inline void dio_zero_block(struct dio *dio, struct dio_submit *sdio,
853 int end, struct buffer_head *m 872 int end, struct buffer_head *map_bh)
854 { 873 {
855 unsigned dio_blocks_per_fs_block; 874 unsigned dio_blocks_per_fs_block;
856 unsigned this_chunk_blocks; /* In 875 unsigned this_chunk_blocks; /* In dio_blocks */
857 unsigned this_chunk_bytes; 876 unsigned this_chunk_bytes;
858 struct page *page; 877 struct page *page;
859 878
860 sdio->start_zero_done = 1; 879 sdio->start_zero_done = 1;
861 if (!sdio->blkfactor || !buffer_new(ma 880 if (!sdio->blkfactor || !buffer_new(map_bh))
862 return; 881 return;
863 882
864 dio_blocks_per_fs_block = 1 << sdio->b 883 dio_blocks_per_fs_block = 1 << sdio->blkfactor;
865 this_chunk_blocks = sdio->block_in_fil 884 this_chunk_blocks = sdio->block_in_file & (dio_blocks_per_fs_block - 1);
866 885
867 if (!this_chunk_blocks) 886 if (!this_chunk_blocks)
868 return; 887 return;
869 888
870 /* 889 /*
871 * We need to zero out part of an fs b 890 * We need to zero out part of an fs block. It is either at the
872 * beginning or the end of the fs bloc 891 * beginning or the end of the fs block.
873 */ 892 */
874 if (end) 893 if (end)
875 this_chunk_blocks = dio_blocks 894 this_chunk_blocks = dio_blocks_per_fs_block - this_chunk_blocks;
876 895
877 this_chunk_bytes = this_chunk_blocks < 896 this_chunk_bytes = this_chunk_blocks << sdio->blkbits;
878 897
879 page = ZERO_PAGE(0); 898 page = ZERO_PAGE(0);
880 if (submit_page_section(dio, sdio, pag 899 if (submit_page_section(dio, sdio, page, 0, this_chunk_bytes,
881 sdio->next_blo 900 sdio->next_block_for_io, map_bh))
882 return; 901 return;
883 902
884 sdio->next_block_for_io += this_chunk_ 903 sdio->next_block_for_io += this_chunk_blocks;
885 } 904 }
886 905
887 /* 906 /*
888 * Walk the user pages, and the file, mapping 907 * Walk the user pages, and the file, mapping blocks to disk and generating
889 * a sequence of (page,offset,len,block) mappi 908 * a sequence of (page,offset,len,block) mappings. These mappings are injected
890 * into submit_page_section(), which takes car 909 * into submit_page_section(), which takes care of the next stage of submission
891 * 910 *
892 * Direct IO against a blockdev is different f 911 * Direct IO against a blockdev is different from a file. Because we can
893 * happily perform page-sized but 512-byte ali 912 * happily perform page-sized but 512-byte aligned IOs. It is important that
894 * blockdev IO be able to have fine alignment 913 * blockdev IO be able to have fine alignment and large sizes.
895 * 914 *
896 * So what we do is to permit the ->get_block 915 * So what we do is to permit the ->get_block function to populate bh.b_size
897 * with the size of IO which is permitted at t 916 * with the size of IO which is permitted at this offset and this i_blkbits.
898 * 917 *
899 * For best results, the blockdev should be se 918 * For best results, the blockdev should be set up with 512-byte i_blkbits and
900 * it should set b_size to PAGE_SIZE or more i 919 * it should set b_size to PAGE_SIZE or more inside get_block(). This gives
901 * fine alignment but still allows this functi 920 * fine alignment but still allows this function to work in PAGE_SIZE units.
902 */ 921 */
903 static int do_direct_IO(struct dio *dio, struc 922 static int do_direct_IO(struct dio *dio, struct dio_submit *sdio,
904 struct buffer_head *ma 923 struct buffer_head *map_bh)
905 { 924 {
906 const enum req_op dio_op = dio->opf & 925 const enum req_op dio_op = dio->opf & REQ_OP_MASK;
907 const unsigned blkbits = sdio->blkbits 926 const unsigned blkbits = sdio->blkbits;
908 const unsigned i_blkbits = blkbits + s 927 const unsigned i_blkbits = blkbits + sdio->blkfactor;
909 int ret = 0; 928 int ret = 0;
910 929
911 while (sdio->block_in_file < sdio->fin 930 while (sdio->block_in_file < sdio->final_block_in_request) {
912 struct page *page; 931 struct page *page;
913 size_t from, to; 932 size_t from, to;
914 933
915 page = dio_get_page(dio, sdio) 934 page = dio_get_page(dio, sdio);
916 if (IS_ERR(page)) { 935 if (IS_ERR(page)) {
917 ret = PTR_ERR(page); 936 ret = PTR_ERR(page);
918 goto out; 937 goto out;
919 } 938 }
920 from = sdio->head ? 0 : sdio-> 939 from = sdio->head ? 0 : sdio->from;
921 to = (sdio->head == sdio->tail 940 to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE;
922 sdio->head++; 941 sdio->head++;
923 942
924 while (from < to) { 943 while (from < to) {
925 unsigned this_chunk_by 944 unsigned this_chunk_bytes; /* # of bytes mapped */
926 unsigned this_chunk_bl 945 unsigned this_chunk_blocks; /* # of blocks */
927 unsigned u; 946 unsigned u;
928 947
929 if (sdio->blocks_avail 948 if (sdio->blocks_available == 0) {
930 /* 949 /*
931 * Need to go 950 * Need to go and map some more disk
932 */ 951 */
933 unsigned long 952 unsigned long blkmask;
934 unsigned long 953 unsigned long dio_remainder;
935 954
936 ret = get_more 955 ret = get_more_blocks(dio, sdio, map_bh);
937 if (ret) { 956 if (ret) {
938 dio_un !! 957 put_page(page);
939 goto o 958 goto out;
940 } 959 }
941 if (!buffer_ma 960 if (!buffer_mapped(map_bh))
942 goto d 961 goto do_holes;
943 962
944 sdio->blocks_a 963 sdio->blocks_available =
945 964 map_bh->b_size >> blkbits;
946 sdio->next_blo 965 sdio->next_block_for_io =
947 map_bh 966 map_bh->b_blocknr << sdio->blkfactor;
948 if (buffer_new 967 if (buffer_new(map_bh)) {
949 clean_ 968 clean_bdev_aliases(
950 969 map_bh->b_bdev,
951 970 map_bh->b_blocknr,
952 971 map_bh->b_size >> i_blkbits);
953 } 972 }
954 973
955 if (!sdio->blk 974 if (!sdio->blkfactor)
956 goto d 975 goto do_holes;
957 976
958 blkmask = (1 < 977 blkmask = (1 << sdio->blkfactor) - 1;
959 dio_remainder 978 dio_remainder = (sdio->block_in_file & blkmask);
960 979
961 /* 980 /*
962 * If we are a 981 * If we are at the start of IO and that IO
963 * starts part 982 * starts partway into a fs-block,
964 * dio_remaind 983 * dio_remainder will be non-zero. If the IO
965 * is a read t 984 * is a read then we can simply advance the IO
966 * cursor to t 985 * cursor to the first block which is to be
967 * read. But 986 * read. But if the IO is a write and the
968 * block was n 987 * block was newly allocated we cannot do that;
969 * the start o 988 * the start of the fs block must be zeroed out
970 * on-disk 989 * on-disk
971 */ 990 */
972 if (!buffer_ne 991 if (!buffer_new(map_bh))
973 sdio-> 992 sdio->next_block_for_io += dio_remainder;
974 sdio->blocks_a 993 sdio->blocks_available -= dio_remainder;
975 } 994 }
976 do_holes: 995 do_holes:
977 /* Handle holes */ 996 /* Handle holes */
978 if (!buffer_mapped(map 997 if (!buffer_mapped(map_bh)) {
979 loff_t i_size_ 998 loff_t i_size_aligned;
980 999
981 /* AKPM: eargh 1000 /* AKPM: eargh, -ENOTBLK is a hack */
982 if (dio_op == 1001 if (dio_op == REQ_OP_WRITE) {
983 dio_un !! 1002 put_page(page);
984 return 1003 return -ENOTBLK;
985 } 1004 }
986 1005
987 /* 1006 /*
988 * Be sure to 1007 * Be sure to account for a partial block as the
989 * last block 1008 * last block in the file
990 */ 1009 */
991 i_size_aligned 1010 i_size_aligned = ALIGN(i_size_read(dio->inode),
992 1011 1 << blkbits);
993 if (sdio->bloc 1012 if (sdio->block_in_file >=
994 1013 i_size_aligned >> blkbits) {
995 /* We 1014 /* We hit eof */
996 dio_un !! 1015 put_page(page);
997 goto o 1016 goto out;
998 } 1017 }
999 zero_user(page 1018 zero_user(page, from, 1 << blkbits);
1000 sdio->block_i 1019 sdio->block_in_file++;
1001 from += 1 << 1020 from += 1 << blkbits;
1002 dio->result + 1021 dio->result += 1 << blkbits;
1003 goto next_blo 1022 goto next_block;
1004 } 1023 }
1005 1024
1006 /* 1025 /*
1007 * If we're performin 1026 * If we're performing IO which has an alignment which
1008 * is finer than the 1027 * is finer than the underlying fs, go check to see if
1009 * we must zero out t 1028 * we must zero out the start of this block.
1010 */ 1029 */
1011 if (unlikely(sdio->bl 1030 if (unlikely(sdio->blkfactor && !sdio->start_zero_done))
1012 dio_zero_bloc 1031 dio_zero_block(dio, sdio, 0, map_bh);
1013 1032
1014 /* 1033 /*
1015 * Work out, in this_ 1034 * Work out, in this_chunk_blocks, how much disk we
1016 * can add to this pa 1035 * can add to this page
1017 */ 1036 */
1018 this_chunk_blocks = s 1037 this_chunk_blocks = sdio->blocks_available;
1019 u = (to - from) >> bl 1038 u = (to - from) >> blkbits;
1020 if (this_chunk_blocks 1039 if (this_chunk_blocks > u)
1021 this_chunk_bl 1040 this_chunk_blocks = u;
1022 u = sdio->final_block 1041 u = sdio->final_block_in_request - sdio->block_in_file;
1023 if (this_chunk_blocks 1042 if (this_chunk_blocks > u)
1024 this_chunk_bl 1043 this_chunk_blocks = u;
1025 this_chunk_bytes = th 1044 this_chunk_bytes = this_chunk_blocks << blkbits;
1026 BUG_ON(this_chunk_byt 1045 BUG_ON(this_chunk_bytes == 0);
1027 1046
1028 if (this_chunk_blocks 1047 if (this_chunk_blocks == sdio->blocks_available)
1029 sdio->boundar 1048 sdio->boundary = buffer_boundary(map_bh);
1030 ret = submit_page_sec 1049 ret = submit_page_section(dio, sdio, page,
1031 1050 from,
1032 1051 this_chunk_bytes,
1033 1052 sdio->next_block_for_io,
1034 1053 map_bh);
1035 if (ret) { 1054 if (ret) {
1036 dio_unpin_pag !! 1055 put_page(page);
1037 goto out; 1056 goto out;
1038 } 1057 }
1039 sdio->next_block_for_ 1058 sdio->next_block_for_io += this_chunk_blocks;
1040 1059
1041 sdio->block_in_file + 1060 sdio->block_in_file += this_chunk_blocks;
1042 from += this_chunk_by 1061 from += this_chunk_bytes;
1043 dio->result += this_c 1062 dio->result += this_chunk_bytes;
1044 sdio->blocks_availabl 1063 sdio->blocks_available -= this_chunk_blocks;
1045 next_block: 1064 next_block:
1046 BUG_ON(sdio->block_in 1065 BUG_ON(sdio->block_in_file > sdio->final_block_in_request);
1047 if (sdio->block_in_fi 1066 if (sdio->block_in_file == sdio->final_block_in_request)
1048 break; 1067 break;
1049 } 1068 }
1050 1069
1051 /* Drop the pin which was tak !! 1070 /* Drop the ref which was taken in get_user_pages() */
1052 dio_unpin_page(dio, page); !! 1071 put_page(page);
1053 } 1072 }
1054 out: 1073 out:
1055 return ret; 1074 return ret;
1056 } 1075 }
1057 1076
1058 static inline int drop_refcount(struct dio *d 1077 static inline int drop_refcount(struct dio *dio)
1059 { 1078 {
1060 int ret2; 1079 int ret2;
1061 unsigned long flags; 1080 unsigned long flags;
1062 1081
1063 /* 1082 /*
1064 * Sync will always be dropping the f 1083 * Sync will always be dropping the final ref and completing the
1065 * operation. AIO can if it was a br 1084 * operation. AIO can if it was a broken operation described above or
1066 * in fact if all the bios race to co 1085 * in fact if all the bios race to complete before we get here. In
1067 * that case dio_complete() translate 1086 * that case dio_complete() translates the EIOCBQUEUED into the proper
1068 * return code that the caller will h 1087 * return code that the caller will hand to ->complete().
1069 * 1088 *
1070 * This is managed by the bio_lock in 1089 * This is managed by the bio_lock instead of being an atomic_t so that
1071 * completion paths can drop their re 1090 * completion paths can drop their ref and use the remaining count to
1072 * decide to wake the submission path 1091 * decide to wake the submission path atomically.
1073 */ 1092 */
1074 spin_lock_irqsave(&dio->bio_lock, fla 1093 spin_lock_irqsave(&dio->bio_lock, flags);
1075 ret2 = --dio->refcount; 1094 ret2 = --dio->refcount;
1076 spin_unlock_irqrestore(&dio->bio_lock 1095 spin_unlock_irqrestore(&dio->bio_lock, flags);
1077 return ret2; 1096 return ret2;
1078 } 1097 }
1079 1098
1080 /* 1099 /*
1081 * This is a library function for use by file 1100 * This is a library function for use by filesystem drivers.
1082 * 1101 *
1083 * The locking rules are governed by the flag 1102 * The locking rules are governed by the flags parameter:
1084 * - if the flags value contains DIO_LOCKING 1103 * - if the flags value contains DIO_LOCKING we use a fancy locking
1085 * scheme for dumb filesystems. 1104 * scheme for dumb filesystems.
1086 * For writes this function is called unde 1105 * For writes this function is called under i_mutex and returns with
1087 * i_mutex held, for reads, i_mutex is not 1106 * i_mutex held, for reads, i_mutex is not held on entry, but it is
1088 * taken and dropped again before returnin 1107 * taken and dropped again before returning.
1089 * - if the flags value does NOT contain DIO 1108 * - if the flags value does NOT contain DIO_LOCKING we don't use any
1090 * internal locking but rather rely on the 1109 * internal locking but rather rely on the filesystem to synchronize
1091 * direct I/O reads/writes versus each oth 1110 * direct I/O reads/writes versus each other and truncate.
1092 * 1111 *
1093 * To help with locking against truncate we i 1112 * To help with locking against truncate we incremented the i_dio_count
1094 * counter before starting direct I/O, and de 1113 * counter before starting direct I/O, and decrement it once we are done.
1095 * Truncate can wait for it to reach zero to 1114 * Truncate can wait for it to reach zero to provide exclusion. It is
1096 * expected that filesystem provide exclusion 1115 * expected that filesystem provide exclusion between new direct I/O
1097 * and truncates. For DIO_LOCKING filesystem 1116 * and truncates. For DIO_LOCKING filesystems this is done by i_mutex,
1098 * but other filesystems need to take care of 1117 * but other filesystems need to take care of this on their own.
1099 * 1118 *
1100 * NOTE: if you pass "sdio" to anything by po 1119 * NOTE: if you pass "sdio" to anything by pointer make sure that function
1101 * is always inlined. Otherwise gcc is unable 1120 * is always inlined. Otherwise gcc is unable to split the structure into
1102 * individual fields and will generate much w 1121 * individual fields and will generate much worse code. This is important
1103 * for the whole file. 1122 * for the whole file.
1104 */ 1123 */
1105 ssize_t __blockdev_direct_IO(struct kiocb *io 1124 ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
1106 struct block_device *bdev, st 1125 struct block_device *bdev, struct iov_iter *iter,
1107 get_block_t get_block, dio_io 1126 get_block_t get_block, dio_iodone_t end_io,
1108 int flags) !! 1127 dio_submit_t submit_io, int flags)
1109 { 1128 {
1110 unsigned i_blkbits = READ_ONCE(inode- 1129 unsigned i_blkbits = READ_ONCE(inode->i_blkbits);
1111 unsigned blkbits = i_blkbits; 1130 unsigned blkbits = i_blkbits;
1112 unsigned blocksize_mask = (1 << blkbi 1131 unsigned blocksize_mask = (1 << blkbits) - 1;
1113 ssize_t retval = -EINVAL; 1132 ssize_t retval = -EINVAL;
1114 const size_t count = iov_iter_count(i 1133 const size_t count = iov_iter_count(iter);
1115 loff_t offset = iocb->ki_pos; 1134 loff_t offset = iocb->ki_pos;
1116 const loff_t end = offset + count; 1135 const loff_t end = offset + count;
1117 struct dio *dio; 1136 struct dio *dio;
1118 struct dio_submit sdio = { NULL, }; !! 1137 struct dio_submit sdio = { 0, };
1119 struct buffer_head map_bh = { 0, }; 1138 struct buffer_head map_bh = { 0, };
1120 struct blk_plug plug; 1139 struct blk_plug plug;
1121 unsigned long align = offset | iov_it 1140 unsigned long align = offset | iov_iter_alignment(iter);
1122 1141
>> 1142 /*
>> 1143 * Avoid references to bdev if not absolutely needed to give
>> 1144 * the early prefetch in the caller enough time.
>> 1145 */
>> 1146
1123 /* watch out for a 0 len io from a tr 1147 /* watch out for a 0 len io from a tricksy fs */
1124 if (iov_iter_rw(iter) == READ && !cou 1148 if (iov_iter_rw(iter) == READ && !count)
1125 return 0; 1149 return 0;
1126 1150
1127 dio = kmem_cache_alloc(dio_cache, GFP 1151 dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
1128 if (!dio) 1152 if (!dio)
1129 return -ENOMEM; 1153 return -ENOMEM;
1130 /* 1154 /*
1131 * Believe it or not, zeroing out the 1155 * Believe it or not, zeroing out the page array caused a .5%
1132 * performance regression in a databa 1156 * performance regression in a database benchmark. So, we take
1133 * care to only zero out what's neede 1157 * care to only zero out what's needed.
1134 */ 1158 */
1135 memset(dio, 0, offsetof(struct dio, p 1159 memset(dio, 0, offsetof(struct dio, pages));
1136 1160
1137 dio->flags = flags; 1161 dio->flags = flags;
1138 if (dio->flags & DIO_LOCKING && iov_i 1162 if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) {
1139 /* will be released by direct 1163 /* will be released by direct_io_worker */
1140 inode_lock(inode); 1164 inode_lock(inode);
1141 } 1165 }
1142 dio->is_pinned = iov_iter_extract_wil <<
1143 1166
1144 /* Once we sampled i_size check for r 1167 /* Once we sampled i_size check for reads beyond EOF */
1145 dio->i_size = i_size_read(inode); 1168 dio->i_size = i_size_read(inode);
1146 if (iov_iter_rw(iter) == READ && offs 1169 if (iov_iter_rw(iter) == READ && offset >= dio->i_size) {
1147 retval = 0; 1170 retval = 0;
1148 goto fail_dio; 1171 goto fail_dio;
1149 } 1172 }
1150 1173
1151 if (align & blocksize_mask) { 1174 if (align & blocksize_mask) {
1152 if (bdev) 1175 if (bdev)
1153 blkbits = blksize_bit 1176 blkbits = blksize_bits(bdev_logical_block_size(bdev));
1154 blocksize_mask = (1 << blkbit 1177 blocksize_mask = (1 << blkbits) - 1;
1155 if (align & blocksize_mask) 1178 if (align & blocksize_mask)
1156 goto fail_dio; 1179 goto fail_dio;
1157 } 1180 }
1158 1181
1159 if (dio->flags & DIO_LOCKING && iov_i 1182 if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ) {
1160 struct address_space *mapping 1183 struct address_space *mapping = iocb->ki_filp->f_mapping;
1161 1184
1162 retval = filemap_write_and_wa 1185 retval = filemap_write_and_wait_range(mapping, offset, end - 1);
1163 if (retval) 1186 if (retval)
1164 goto fail_dio; 1187 goto fail_dio;
1165 } 1188 }
1166 1189
1167 /* 1190 /*
1168 * For file extending writes updating 1191 * For file extending writes updating i_size before data writeouts
1169 * complete can expose uninitialized 1192 * complete can expose uninitialized blocks in dumb filesystems.
1170 * In that case we need to wait for I 1193 * In that case we need to wait for I/O completion even if asked
1171 * for an asynchronous write. 1194 * for an asynchronous write.
1172 */ 1195 */
1173 if (is_sync_kiocb(iocb)) 1196 if (is_sync_kiocb(iocb))
1174 dio->is_async = false; 1197 dio->is_async = false;
1175 else if (iov_iter_rw(iter) == WRITE & 1198 else if (iov_iter_rw(iter) == WRITE && end > i_size_read(inode))
1176 dio->is_async = false; 1199 dio->is_async = false;
1177 else 1200 else
1178 dio->is_async = true; 1201 dio->is_async = true;
1179 1202
1180 dio->inode = inode; 1203 dio->inode = inode;
1181 if (iov_iter_rw(iter) == WRITE) { 1204 if (iov_iter_rw(iter) == WRITE) {
1182 dio->opf = REQ_OP_WRITE | REQ 1205 dio->opf = REQ_OP_WRITE | REQ_SYNC | REQ_IDLE;
1183 if (iocb->ki_flags & IOCB_NOW 1206 if (iocb->ki_flags & IOCB_NOWAIT)
1184 dio->opf |= REQ_NOWAI 1207 dio->opf |= REQ_NOWAIT;
1185 } else { 1208 } else {
1186 dio->opf = REQ_OP_READ; 1209 dio->opf = REQ_OP_READ;
1187 } 1210 }
1188 1211
1189 /* 1212 /*
1190 * For AIO O_(D)SYNC writes we need t 1213 * For AIO O_(D)SYNC writes we need to defer completions to a workqueue
1191 * so that we can call ->fsync. 1214 * so that we can call ->fsync.
1192 */ 1215 */
1193 if (dio->is_async && iov_iter_rw(iter 1216 if (dio->is_async && iov_iter_rw(iter) == WRITE) {
1194 retval = 0; 1217 retval = 0;
1195 if (iocb_is_dsync(iocb)) 1218 if (iocb_is_dsync(iocb))
1196 retval = dio_set_defe 1219 retval = dio_set_defer_completion(dio);
1197 else if (!dio->inode->i_sb->s 1220 else if (!dio->inode->i_sb->s_dio_done_wq) {
1198 /* 1221 /*
1199 * In case of AIO wri 1222 * In case of AIO write racing with buffered read we
1200 * need to defer comp 1223 * need to defer completion. We can't decide this now,
1201 * however the workqu 1224 * however the workqueue needs to be initialized here.
1202 */ 1225 */
1203 retval = sb_init_dio_ 1226 retval = sb_init_dio_done_wq(dio->inode->i_sb);
1204 } 1227 }
1205 if (retval) 1228 if (retval)
1206 goto fail_dio; 1229 goto fail_dio;
1207 } 1230 }
1208 1231
1209 /* 1232 /*
1210 * Will be decremented at I/O complet 1233 * Will be decremented at I/O completion time.
1211 */ 1234 */
1212 inode_dio_begin(inode); 1235 inode_dio_begin(inode);
1213 1236
>> 1237 retval = 0;
1214 sdio.blkbits = blkbits; 1238 sdio.blkbits = blkbits;
1215 sdio.blkfactor = i_blkbits - blkbits; 1239 sdio.blkfactor = i_blkbits - blkbits;
1216 sdio.block_in_file = offset >> blkbit 1240 sdio.block_in_file = offset >> blkbits;
1217 1241
1218 sdio.get_block = get_block; 1242 sdio.get_block = get_block;
1219 dio->end_io = end_io; 1243 dio->end_io = end_io;
>> 1244 sdio.submit_io = submit_io;
1220 sdio.final_block_in_bio = -1; 1245 sdio.final_block_in_bio = -1;
1221 sdio.next_block_for_io = -1; 1246 sdio.next_block_for_io = -1;
1222 1247
1223 dio->iocb = iocb; 1248 dio->iocb = iocb;
1224 1249
1225 spin_lock_init(&dio->bio_lock); 1250 spin_lock_init(&dio->bio_lock);
1226 dio->refcount = 1; 1251 dio->refcount = 1;
1227 1252
1228 dio->should_dirty = user_backed_iter( 1253 dio->should_dirty = user_backed_iter(iter) && iov_iter_rw(iter) == READ;
1229 sdio.iter = iter; 1254 sdio.iter = iter;
1230 sdio.final_block_in_request = end >> 1255 sdio.final_block_in_request = end >> blkbits;
1231 1256
1232 /* 1257 /*
1233 * In case of non-aligned buffers, we 1258 * In case of non-aligned buffers, we may need 2 more
1234 * pages since we need to zero out fi 1259 * pages since we need to zero out first and last block.
1235 */ 1260 */
1236 if (unlikely(sdio.blkfactor)) 1261 if (unlikely(sdio.blkfactor))
1237 sdio.pages_in_io = 2; 1262 sdio.pages_in_io = 2;
1238 1263
1239 sdio.pages_in_io += iov_iter_npages(i 1264 sdio.pages_in_io += iov_iter_npages(iter, INT_MAX);
1240 1265
1241 blk_start_plug(&plug); 1266 blk_start_plug(&plug);
1242 1267
1243 retval = do_direct_IO(dio, &sdio, &ma 1268 retval = do_direct_IO(dio, &sdio, &map_bh);
1244 if (retval) 1269 if (retval)
1245 dio_cleanup(dio, &sdio); 1270 dio_cleanup(dio, &sdio);
1246 1271
1247 if (retval == -ENOTBLK) { 1272 if (retval == -ENOTBLK) {
1248 /* 1273 /*
1249 * The remaining part of the 1274 * The remaining part of the request will be
1250 * handled by buffered I/O wh 1275 * handled by buffered I/O when we return
1251 */ 1276 */
1252 retval = 0; 1277 retval = 0;
1253 } 1278 }
1254 /* 1279 /*
1255 * There may be some unwritten disk a 1280 * There may be some unwritten disk at the end of a part-written
1256 * fs-block-sized block. Go zero tha 1281 * fs-block-sized block. Go zero that now.
1257 */ 1282 */
1258 dio_zero_block(dio, &sdio, 1, &map_bh 1283 dio_zero_block(dio, &sdio, 1, &map_bh);
1259 1284
1260 if (sdio.cur_page) { 1285 if (sdio.cur_page) {
1261 ssize_t ret2; 1286 ssize_t ret2;
1262 1287
1263 ret2 = dio_send_cur_page(dio, 1288 ret2 = dio_send_cur_page(dio, &sdio, &map_bh);
1264 if (retval == 0) 1289 if (retval == 0)
1265 retval = ret2; 1290 retval = ret2;
1266 dio_unpin_page(dio, sdio.cur_ !! 1291 put_page(sdio.cur_page);
1267 sdio.cur_page = NULL; 1292 sdio.cur_page = NULL;
1268 } 1293 }
1269 if (sdio.bio) 1294 if (sdio.bio)
1270 dio_bio_submit(dio, &sdio); 1295 dio_bio_submit(dio, &sdio);
1271 1296
1272 blk_finish_plug(&plug); 1297 blk_finish_plug(&plug);
1273 1298
1274 /* 1299 /*
1275 * It is possible that, we return sho 1300 * It is possible that, we return short IO due to end of file.
1276 * In that case, we need to release a 1301 * In that case, we need to release all the pages we got hold on.
1277 */ 1302 */
1278 dio_cleanup(dio, &sdio); 1303 dio_cleanup(dio, &sdio);
1279 1304
1280 /* 1305 /*
1281 * All block lookups have been perfor 1306 * All block lookups have been performed. For READ requests
1282 * we can let i_mutex go now that its 1307 * we can let i_mutex go now that its achieved its purpose
1283 * of protecting us from looking up u 1308 * of protecting us from looking up uninitialized blocks.
1284 */ 1309 */
1285 if (iov_iter_rw(iter) == READ && (dio 1310 if (iov_iter_rw(iter) == READ && (dio->flags & DIO_LOCKING))
1286 inode_unlock(dio->inode); 1311 inode_unlock(dio->inode);
1287 1312
1288 /* 1313 /*
1289 * The only time we want to leave bio 1314 * The only time we want to leave bios in flight is when a successful
1290 * partial aio read or full aio write 1315 * partial aio read or full aio write have been setup. In that case
1291 * bio completion will call aio_compl 1316 * bio completion will call aio_complete. The only time it's safe to
1292 * call aio_complete is when we retur 1317 * call aio_complete is when we return -EIOCBQUEUED, so we key on that.
1293 * This had *better* be the only plac 1318 * This had *better* be the only place that raises -EIOCBQUEUED.
1294 */ 1319 */
1295 BUG_ON(retval == -EIOCBQUEUED); 1320 BUG_ON(retval == -EIOCBQUEUED);
1296 if (dio->is_async && retval == 0 && d 1321 if (dio->is_async && retval == 0 && dio->result &&
1297 (iov_iter_rw(iter) == READ || dio 1322 (iov_iter_rw(iter) == READ || dio->result == count))
1298 retval = -EIOCBQUEUED; 1323 retval = -EIOCBQUEUED;
1299 else 1324 else
1300 dio_await_completion(dio); 1325 dio_await_completion(dio);
1301 1326
1302 if (drop_refcount(dio) == 0) { 1327 if (drop_refcount(dio) == 0) {
1303 retval = dio_complete(dio, re 1328 retval = dio_complete(dio, retval, DIO_COMPLETE_INVALIDATE);
1304 } else 1329 } else
1305 BUG_ON(retval != -EIOCBQUEUED 1330 BUG_ON(retval != -EIOCBQUEUED);
1306 1331
1307 return retval; 1332 return retval;
1308 1333
1309 fail_dio: 1334 fail_dio:
1310 if (dio->flags & DIO_LOCKING && iov_i 1335 if (dio->flags & DIO_LOCKING && iov_iter_rw(iter) == READ)
1311 inode_unlock(inode); 1336 inode_unlock(inode);
1312 1337
1313 kmem_cache_free(dio_cache, dio); 1338 kmem_cache_free(dio_cache, dio);
1314 return retval; 1339 return retval;
1315 } 1340 }
1316 EXPORT_SYMBOL(__blockdev_direct_IO); 1341 EXPORT_SYMBOL(__blockdev_direct_IO);
1317 1342
1318 static __init int dio_init(void) 1343 static __init int dio_init(void)
1319 { 1344 {
1320 dio_cache = KMEM_CACHE(dio, SLAB_PANI 1345 dio_cache = KMEM_CACHE(dio, SLAB_PANIC);
1321 return 0; 1346 return 0;
1322 } 1347 }
1323 module_init(dio_init) 1348 module_init(dio_init)
1324 1349
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