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