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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* kiocb-using read/write
3 *
4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/mount.h>
9#include <linux/slab.h>
10#include <linux/file.h>
11#include <linux/uio.h>
12#include <linux/falloc.h>
13#include <linux/sched/mm.h>
14#include <trace/events/fscache.h>
15#include "internal.h"
16
17struct cachefiles_kiocb {
18 struct kiocb iocb;
19 refcount_t ki_refcnt;
20 loff_t start;
21 union {
22 size_t skipped;
23 size_t len;
24 };
25 struct cachefiles_object *object;
26 netfs_io_terminated_t term_func;
27 void *term_func_priv;
28 bool was_async;
29 unsigned int inval_counter; /* Copy of cookie->inval_counter */
30 u64 b_writing;
31};
32
33static inline void cachefiles_put_kiocb(struct cachefiles_kiocb *ki)
34{
35 if (refcount_dec_and_test(&ki->ki_refcnt)) {
36 cachefiles_put_object(ki->object, cachefiles_obj_put_ioreq);
37 fput(ki->iocb.ki_filp);
38 kfree(ki);
39 }
40}
41
42/*
43 * Handle completion of a read from the cache.
44 */
45static void cachefiles_read_complete(struct kiocb *iocb, long ret)
46{
47 struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
48 struct inode *inode = file_inode(ki->iocb.ki_filp);
49
50 _enter("%ld", ret);
51
52 if (ret < 0)
53 trace_cachefiles_io_error(ki->object, inode, ret,
54 cachefiles_trace_read_error);
55
56 if (ki->term_func) {
57 if (ret >= 0) {
58 if (ki->object->cookie->inval_counter == ki->inval_counter)
59 ki->skipped += ret;
60 else
61 ret = -ESTALE;
62 }
63
64 ki->term_func(ki->term_func_priv, ret, ki->was_async);
65 }
66
67 cachefiles_put_kiocb(ki);
68}
69
70/*
71 * Initiate a read from the cache.
72 */
73static int cachefiles_read(struct netfs_cache_resources *cres,
74 loff_t start_pos,
75 struct iov_iter *iter,
76 enum netfs_read_from_hole read_hole,
77 netfs_io_terminated_t term_func,
78 void *term_func_priv)
79{
80 struct cachefiles_object *object;
81 struct cachefiles_kiocb *ki;
82 struct file *file;
83 unsigned int old_nofs;
84 ssize_t ret = -ENOBUFS;
85 size_t len = iov_iter_count(iter), skipped = 0;
86
87 if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ))
88 goto presubmission_error;
89
90 fscache_count_read();
91 object = cachefiles_cres_object(cres);
92 file = cachefiles_cres_file(cres);
93
94 _enter("%pD,%li,%llx,%zx/%llx",
95 file, file_inode(file)->i_ino, start_pos, len,
96 i_size_read(file_inode(file)));
97
98 /* If the caller asked us to seek for data before doing the read, then
99 * we should do that now. If we find a gap, we fill it with zeros.
100 */
101 if (read_hole != NETFS_READ_HOLE_IGNORE) {
102 loff_t off = start_pos, off2;
103
104 off2 = cachefiles_inject_read_error();
105 if (off2 == 0)
106 off2 = vfs_llseek(file, off, SEEK_DATA);
107 if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO && off2 != -ENXIO) {
108 skipped = 0;
109 ret = off2;
110 goto presubmission_error;
111 }
112
113 if (off2 == -ENXIO || off2 >= start_pos + len) {
114 /* The region is beyond the EOF or there's no more data
115 * in the region, so clear the rest of the buffer and
116 * return success.
117 */
118 ret = -ENODATA;
119 if (read_hole == NETFS_READ_HOLE_FAIL)
120 goto presubmission_error;
121
122 iov_iter_zero(len, iter);
123 skipped = len;
124 ret = 0;
125 goto presubmission_error;
126 }
127
128 skipped = off2 - off;
129 iov_iter_zero(skipped, iter);
130 }
131
132 ret = -ENOMEM;
133 ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
134 if (!ki)
135 goto presubmission_error;
136
137 refcount_set(&ki->ki_refcnt, 2);
138 ki->iocb.ki_filp = file;
139 ki->iocb.ki_pos = start_pos + skipped;
140 ki->iocb.ki_flags = IOCB_DIRECT;
141 ki->iocb.ki_ioprio = get_current_ioprio();
142 ki->skipped = skipped;
143 ki->object = object;
144 ki->inval_counter = cres->inval_counter;
145 ki->term_func = term_func;
146 ki->term_func_priv = term_func_priv;
147 ki->was_async = true;
148
149 if (ki->term_func)
150 ki->iocb.ki_complete = cachefiles_read_complete;
151
152 get_file(ki->iocb.ki_filp);
153 cachefiles_grab_object(object, cachefiles_obj_get_ioreq);
154
155 trace_cachefiles_read(object, file_inode(file), ki->iocb.ki_pos, len - skipped);
156 old_nofs = memalloc_nofs_save();
157 ret = cachefiles_inject_read_error();
158 if (ret == 0)
159 ret = vfs_iocb_iter_read(file, &ki->iocb, iter);
160 memalloc_nofs_restore(old_nofs);
161 switch (ret) {
162 case -EIOCBQUEUED:
163 goto in_progress;
164
165 case -ERESTARTSYS:
166 case -ERESTARTNOINTR:
167 case -ERESTARTNOHAND:
168 case -ERESTART_RESTARTBLOCK:
169 /* There's no easy way to restart the syscall since other AIO's
170 * may be already running. Just fail this IO with EINTR.
171 */
172 ret = -EINTR;
173 fallthrough;
174 default:
175 ki->was_async = false;
176 cachefiles_read_complete(&ki->iocb, ret);
177 if (ret > 0)
178 ret = 0;
179 break;
180 }
181
182in_progress:
183 cachefiles_put_kiocb(ki);
184 _leave(" = %zd", ret);
185 return ret;
186
187presubmission_error:
188 if (term_func)
189 term_func(term_func_priv, ret < 0 ? ret : skipped, false);
190 return ret;
191}
192
193/*
194 * Query the occupancy of the cache in a region, returning where the next chunk
195 * of data starts and how long it is.
196 */
197static int cachefiles_query_occupancy(struct netfs_cache_resources *cres,
198 loff_t start, size_t len, size_t granularity,
199 loff_t *_data_start, size_t *_data_len)
200{
201 struct cachefiles_object *object;
202 struct file *file;
203 loff_t off, off2;
204
205 *_data_start = -1;
206 *_data_len = 0;
207
208 if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ))
209 return -ENOBUFS;
210
211 object = cachefiles_cres_object(cres);
212 file = cachefiles_cres_file(cres);
213 granularity = max_t(size_t, object->volume->cache->bsize, granularity);
214
215 _enter("%pD,%li,%llx,%zx/%llx",
216 file, file_inode(file)->i_ino, start, len,
217 i_size_read(file_inode(file)));
218
219 off = cachefiles_inject_read_error();
220 if (off == 0)
221 off = vfs_llseek(file, start, SEEK_DATA);
222 if (off == -ENXIO)
223 return -ENODATA; /* Beyond EOF */
224 if (off < 0 && off >= (loff_t)-MAX_ERRNO)
225 return -ENOBUFS; /* Error. */
226 if (round_up(off, granularity) >= start + len)
227 return -ENODATA; /* No data in range */
228
229 off2 = cachefiles_inject_read_error();
230 if (off2 == 0)
231 off2 = vfs_llseek(file, off, SEEK_HOLE);
232 if (off2 == -ENXIO)
233 return -ENODATA; /* Beyond EOF */
234 if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO)
235 return -ENOBUFS; /* Error. */
236
237 /* Round away partial blocks */
238 off = round_up(off, granularity);
239 off2 = round_down(off2, granularity);
240 if (off2 <= off)
241 return -ENODATA;
242
243 *_data_start = off;
244 if (off2 > start + len)
245 *_data_len = len;
246 else
247 *_data_len = off2 - off;
248 return 0;
249}
250
251/*
252 * Handle completion of a write to the cache.
253 */
254static void cachefiles_write_complete(struct kiocb *iocb, long ret)
255{
256 struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
257 struct cachefiles_object *object = ki->object;
258 struct inode *inode = file_inode(ki->iocb.ki_filp);
259
260 _enter("%ld", ret);
261
262 if (ki->was_async)
263 kiocb_end_write(iocb);
264
265 if (ret < 0)
266 trace_cachefiles_io_error(object, inode, ret,
267 cachefiles_trace_write_error);
268
269 atomic_long_sub(ki->b_writing, &object->volume->cache->b_writing);
270 set_bit(FSCACHE_COOKIE_HAVE_DATA, &object->cookie->flags);
271 if (ki->term_func)
272 ki->term_func(ki->term_func_priv, ret, ki->was_async);
273 cachefiles_put_kiocb(ki);
274}
275
276/*
277 * Initiate a write to the cache.
278 */
279int __cachefiles_write(struct cachefiles_object *object,
280 struct file *file,
281 loff_t start_pos,
282 struct iov_iter *iter,
283 netfs_io_terminated_t term_func,
284 void *term_func_priv)
285{
286 struct cachefiles_cache *cache;
287 struct cachefiles_kiocb *ki;
288 unsigned int old_nofs;
289 ssize_t ret;
290 size_t len = iov_iter_count(iter);
291
292 fscache_count_write();
293 cache = object->volume->cache;
294
295 _enter("%pD,%li,%llx,%zx/%llx",
296 file, file_inode(file)->i_ino, start_pos, len,
297 i_size_read(file_inode(file)));
298
299 ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
300 if (!ki) {
301 if (term_func)
302 term_func(term_func_priv, -ENOMEM, false);
303 return -ENOMEM;
304 }
305
306 refcount_set(&ki->ki_refcnt, 2);
307 ki->iocb.ki_filp = file;
308 ki->iocb.ki_pos = start_pos;
309 ki->iocb.ki_flags = IOCB_DIRECT | IOCB_WRITE;
310 ki->iocb.ki_ioprio = get_current_ioprio();
311 ki->object = object;
312 ki->start = start_pos;
313 ki->len = len;
314 ki->term_func = term_func;
315 ki->term_func_priv = term_func_priv;
316 ki->was_async = true;
317 ki->b_writing = (len + (1 << cache->bshift) - 1) >> cache->bshift;
318
319 if (ki->term_func)
320 ki->iocb.ki_complete = cachefiles_write_complete;
321 atomic_long_add(ki->b_writing, &cache->b_writing);
322
323 get_file(ki->iocb.ki_filp);
324 cachefiles_grab_object(object, cachefiles_obj_get_ioreq);
325
326 trace_cachefiles_write(object, file_inode(file), ki->iocb.ki_pos, len);
327 old_nofs = memalloc_nofs_save();
328 ret = cachefiles_inject_write_error();
329 if (ret == 0)
330 ret = vfs_iocb_iter_write(file, &ki->iocb, iter);
331 memalloc_nofs_restore(old_nofs);
332 switch (ret) {
333 case -EIOCBQUEUED:
334 goto in_progress;
335
336 case -ERESTARTSYS:
337 case -ERESTARTNOINTR:
338 case -ERESTARTNOHAND:
339 case -ERESTART_RESTARTBLOCK:
340 /* There's no easy way to restart the syscall since other AIO's
341 * may be already running. Just fail this IO with EINTR.
342 */
343 ret = -EINTR;
344 fallthrough;
345 default:
346 ki->was_async = false;
347 cachefiles_write_complete(&ki->iocb, ret);
348 if (ret > 0)
349 ret = 0;
350 break;
351 }
352
353in_progress:
354 cachefiles_put_kiocb(ki);
355 _leave(" = %zd", ret);
356 return ret;
357}
358
359static int cachefiles_write(struct netfs_cache_resources *cres,
360 loff_t start_pos,
361 struct iov_iter *iter,
362 netfs_io_terminated_t term_func,
363 void *term_func_priv)
364{
365 if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE)) {
366 if (term_func)
367 term_func(term_func_priv, -ENOBUFS, false);
368 return -ENOBUFS;
369 }
370
371 return __cachefiles_write(cachefiles_cres_object(cres),
372 cachefiles_cres_file(cres),
373 start_pos, iter,
374 term_func, term_func_priv);
375}
376
377static inline enum netfs_io_source
378cachefiles_do_prepare_read(struct netfs_cache_resources *cres,
379 loff_t start, size_t *_len, loff_t i_size,
380 unsigned long *_flags, ino_t netfs_ino)
381{
382 enum cachefiles_prepare_read_trace why;
383 struct cachefiles_object *object = NULL;
384 struct cachefiles_cache *cache;
385 struct fscache_cookie *cookie = fscache_cres_cookie(cres);
386 const struct cred *saved_cred;
387 struct file *file = cachefiles_cres_file(cres);
388 enum netfs_io_source ret = NETFS_DOWNLOAD_FROM_SERVER;
389 size_t len = *_len;
390 loff_t off, to;
391 ino_t ino = file ? file_inode(file)->i_ino : 0;
392 int rc;
393
394 _enter("%zx @%llx/%llx", len, start, i_size);
395
396 if (start >= i_size) {
397 ret = NETFS_FILL_WITH_ZEROES;
398 why = cachefiles_trace_read_after_eof;
399 goto out_no_object;
400 }
401
402 if (test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags)) {
403 __set_bit(NETFS_SREQ_COPY_TO_CACHE, _flags);
404 why = cachefiles_trace_read_no_data;
405 if (!test_bit(NETFS_SREQ_ONDEMAND, _flags))
406 goto out_no_object;
407 }
408
409 /* The object and the file may be being created in the background. */
410 if (!file) {
411 why = cachefiles_trace_read_no_file;
412 if (!fscache_wait_for_operation(cres, FSCACHE_WANT_READ))
413 goto out_no_object;
414 file = cachefiles_cres_file(cres);
415 if (!file)
416 goto out_no_object;
417 ino = file_inode(file)->i_ino;
418 }
419
420 object = cachefiles_cres_object(cres);
421 cache = object->volume->cache;
422 cachefiles_begin_secure(cache, &saved_cred);
423retry:
424 off = cachefiles_inject_read_error();
425 if (off == 0)
426 off = vfs_llseek(file, start, SEEK_DATA);
427 if (off < 0 && off >= (loff_t)-MAX_ERRNO) {
428 if (off == (loff_t)-ENXIO) {
429 why = cachefiles_trace_read_seek_nxio;
430 goto download_and_store;
431 }
432 trace_cachefiles_io_error(object, file_inode(file), off,
433 cachefiles_trace_seek_error);
434 why = cachefiles_trace_read_seek_error;
435 goto out;
436 }
437
438 if (off >= start + len) {
439 why = cachefiles_trace_read_found_hole;
440 goto download_and_store;
441 }
442
443 if (off > start) {
444 off = round_up(off, cache->bsize);
445 len = off - start;
446 *_len = len;
447 why = cachefiles_trace_read_found_part;
448 goto download_and_store;
449 }
450
451 to = cachefiles_inject_read_error();
452 if (to == 0)
453 to = vfs_llseek(file, start, SEEK_HOLE);
454 if (to < 0 && to >= (loff_t)-MAX_ERRNO) {
455 trace_cachefiles_io_error(object, file_inode(file), to,
456 cachefiles_trace_seek_error);
457 why = cachefiles_trace_read_seek_error;
458 goto out;
459 }
460
461 if (to < start + len) {
462 if (start + len >= i_size)
463 to = round_up(to, cache->bsize);
464 else
465 to = round_down(to, cache->bsize);
466 len = to - start;
467 *_len = len;
468 }
469
470 why = cachefiles_trace_read_have_data;
471 ret = NETFS_READ_FROM_CACHE;
472 goto out;
473
474download_and_store:
475 __set_bit(NETFS_SREQ_COPY_TO_CACHE, _flags);
476 if (test_bit(NETFS_SREQ_ONDEMAND, _flags)) {
477 rc = cachefiles_ondemand_read(object, start, len);
478 if (!rc) {
479 __clear_bit(NETFS_SREQ_ONDEMAND, _flags);
480 goto retry;
481 }
482 ret = NETFS_INVALID_READ;
483 }
484out:
485 cachefiles_end_secure(cache, saved_cred);
486out_no_object:
487 trace_cachefiles_prep_read(object, start, len, *_flags, ret, why, ino, netfs_ino);
488 return ret;
489}
490
491/*
492 * Prepare a read operation, shortening it to a cached/uncached
493 * boundary as appropriate.
494 */
495static enum netfs_io_source cachefiles_prepare_read(struct netfs_io_subrequest *subreq,
496 loff_t i_size)
497{
498 return cachefiles_do_prepare_read(&subreq->rreq->cache_resources,
499 subreq->start, &subreq->len, i_size,
500 &subreq->flags, subreq->rreq->inode->i_ino);
501}
502
503/*
504 * Prepare an on-demand read operation, shortening it to a cached/uncached
505 * boundary as appropriate.
506 */
507static enum netfs_io_source
508cachefiles_prepare_ondemand_read(struct netfs_cache_resources *cres,
509 loff_t start, size_t *_len, loff_t i_size,
510 unsigned long *_flags, ino_t ino)
511{
512 return cachefiles_do_prepare_read(cres, start, _len, i_size, _flags, ino);
513}
514
515/*
516 * Prepare for a write to occur.
517 */
518int __cachefiles_prepare_write(struct cachefiles_object *object,
519 struct file *file,
520 loff_t *_start, size_t *_len, size_t upper_len,
521 bool no_space_allocated_yet)
522{
523 struct cachefiles_cache *cache = object->volume->cache;
524 loff_t start = *_start, pos;
525 size_t len = *_len;
526 int ret;
527
528 /* Round to DIO size */
529 start = round_down(*_start, PAGE_SIZE);
530 if (start != *_start || *_len > upper_len) {
531 /* Probably asked to cache a streaming write written into the
532 * pagecache when the cookie was temporarily out of service to
533 * culling.
534 */
535 fscache_count_dio_misfit();
536 return -ENOBUFS;
537 }
538
539 *_len = round_up(len, PAGE_SIZE);
540
541 /* We need to work out whether there's sufficient disk space to perform
542 * the write - but we can skip that check if we have space already
543 * allocated.
544 */
545 if (no_space_allocated_yet)
546 goto check_space;
547
548 pos = cachefiles_inject_read_error();
549 if (pos == 0)
550 pos = vfs_llseek(file, start, SEEK_DATA);
551 if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
552 if (pos == -ENXIO)
553 goto check_space; /* Unallocated tail */
554 trace_cachefiles_io_error(object, file_inode(file), pos,
555 cachefiles_trace_seek_error);
556 return pos;
557 }
558 if ((u64)pos >= (u64)start + *_len)
559 goto check_space; /* Unallocated region */
560
561 /* We have a block that's at least partially filled - if we're low on
562 * space, we need to see if it's fully allocated. If it's not, we may
563 * want to cull it.
564 */
565 if (cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
566 cachefiles_has_space_check) == 0)
567 return 0; /* Enough space to simply overwrite the whole block */
568
569 pos = cachefiles_inject_read_error();
570 if (pos == 0)
571 pos = vfs_llseek(file, start, SEEK_HOLE);
572 if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
573 trace_cachefiles_io_error(object, file_inode(file), pos,
574 cachefiles_trace_seek_error);
575 return pos;
576 }
577 if ((u64)pos >= (u64)start + *_len)
578 return 0; /* Fully allocated */
579
580 /* Partially allocated, but insufficient space: cull. */
581 fscache_count_no_write_space();
582 ret = cachefiles_inject_remove_error();
583 if (ret == 0)
584 ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
585 start, *_len);
586 if (ret < 0) {
587 trace_cachefiles_io_error(object, file_inode(file), ret,
588 cachefiles_trace_fallocate_error);
589 cachefiles_io_error_obj(object,
590 "CacheFiles: fallocate failed (%d)\n", ret);
591 ret = -EIO;
592 }
593
594 return ret;
595
596check_space:
597 return cachefiles_has_space(cache, 0, *_len / PAGE_SIZE,
598 cachefiles_has_space_for_write);
599}
600
601static int cachefiles_prepare_write(struct netfs_cache_resources *cres,
602 loff_t *_start, size_t *_len, size_t upper_len,
603 loff_t i_size, bool no_space_allocated_yet)
604{
605 struct cachefiles_object *object = cachefiles_cres_object(cres);
606 struct cachefiles_cache *cache = object->volume->cache;
607 const struct cred *saved_cred;
608 int ret;
609
610 if (!cachefiles_cres_file(cres)) {
611 if (!fscache_wait_for_operation(cres, FSCACHE_WANT_WRITE))
612 return -ENOBUFS;
613 if (!cachefiles_cres_file(cres))
614 return -ENOBUFS;
615 }
616
617 cachefiles_begin_secure(cache, &saved_cred);
618 ret = __cachefiles_prepare_write(object, cachefiles_cres_file(cres),
619 _start, _len, upper_len,
620 no_space_allocated_yet);
621 cachefiles_end_secure(cache, saved_cred);
622 return ret;
623}
624
625/*
626 * Clean up an operation.
627 */
628static void cachefiles_end_operation(struct netfs_cache_resources *cres)
629{
630 struct file *file = cachefiles_cres_file(cres);
631
632 if (file)
633 fput(file);
634 fscache_end_cookie_access(fscache_cres_cookie(cres), fscache_access_io_end);
635}
636
637static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
638 .end_operation = cachefiles_end_operation,
639 .read = cachefiles_read,
640 .write = cachefiles_write,
641 .prepare_read = cachefiles_prepare_read,
642 .prepare_write = cachefiles_prepare_write,
643 .prepare_ondemand_read = cachefiles_prepare_ondemand_read,
644 .query_occupancy = cachefiles_query_occupancy,
645};
646
647/*
648 * Open the cache file when beginning a cache operation.
649 */
650bool cachefiles_begin_operation(struct netfs_cache_resources *cres,
651 enum fscache_want_state want_state)
652{
653 struct cachefiles_object *object = cachefiles_cres_object(cres);
654
655 if (!cachefiles_cres_file(cres)) {
656 cres->ops = &cachefiles_netfs_cache_ops;
657 if (object->file) {
658 spin_lock(&object->lock);
659 if (!cres->cache_priv2 && object->file)
660 cres->cache_priv2 = get_file(object->file);
661 spin_unlock(&object->lock);
662 }
663 }
664
665 if (!cachefiles_cres_file(cres) && want_state != FSCACHE_WANT_PARAMS) {
666 pr_err("failed to get cres->file\n");
667 return false;
668 }
669
670 return true;
671}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/* kiocb-using read/write
3 *
4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 */
7
8#include <linux/mount.h>
9#include <linux/slab.h>
10#include <linux/file.h>
11#include <linux/uio.h>
12#include <linux/sched/mm.h>
13#include <linux/netfs.h>
14#include "internal.h"
15
16struct cachefiles_kiocb {
17 struct kiocb iocb;
18 refcount_t ki_refcnt;
19 loff_t start;
20 union {
21 size_t skipped;
22 size_t len;
23 };
24 netfs_io_terminated_t term_func;
25 void *term_func_priv;
26 bool was_async;
27};
28
29static inline void cachefiles_put_kiocb(struct cachefiles_kiocb *ki)
30{
31 if (refcount_dec_and_test(&ki->ki_refcnt)) {
32 fput(ki->iocb.ki_filp);
33 kfree(ki);
34 }
35}
36
37/*
38 * Handle completion of a read from the cache.
39 */
40static void cachefiles_read_complete(struct kiocb *iocb, long ret, long ret2)
41{
42 struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
43
44 _enter("%ld,%ld", ret, ret2);
45
46 if (ki->term_func) {
47 if (ret >= 0)
48 ret += ki->skipped;
49 ki->term_func(ki->term_func_priv, ret, ki->was_async);
50 }
51
52 cachefiles_put_kiocb(ki);
53}
54
55/*
56 * Initiate a read from the cache.
57 */
58static int cachefiles_read(struct netfs_cache_resources *cres,
59 loff_t start_pos,
60 struct iov_iter *iter,
61 bool seek_data,
62 netfs_io_terminated_t term_func,
63 void *term_func_priv)
64{
65 struct cachefiles_kiocb *ki;
66 struct file *file = cres->cache_priv2;
67 unsigned int old_nofs;
68 ssize_t ret = -ENOBUFS;
69 size_t len = iov_iter_count(iter), skipped = 0;
70
71 _enter("%pD,%li,%llx,%zx/%llx",
72 file, file_inode(file)->i_ino, start_pos, len,
73 i_size_read(file->f_inode));
74
75 /* If the caller asked us to seek for data before doing the read, then
76 * we should do that now. If we find a gap, we fill it with zeros.
77 */
78 if (seek_data) {
79 loff_t off = start_pos, off2;
80
81 off2 = vfs_llseek(file, off, SEEK_DATA);
82 if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO && off2 != -ENXIO) {
83 skipped = 0;
84 ret = off2;
85 goto presubmission_error;
86 }
87
88 if (off2 == -ENXIO || off2 >= start_pos + len) {
89 /* The region is beyond the EOF or there's no more data
90 * in the region, so clear the rest of the buffer and
91 * return success.
92 */
93 iov_iter_zero(len, iter);
94 skipped = len;
95 ret = 0;
96 goto presubmission_error;
97 }
98
99 skipped = off2 - off;
100 iov_iter_zero(skipped, iter);
101 }
102
103 ret = -ENOBUFS;
104 ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
105 if (!ki)
106 goto presubmission_error;
107
108 refcount_set(&ki->ki_refcnt, 2);
109 ki->iocb.ki_filp = file;
110 ki->iocb.ki_pos = start_pos + skipped;
111 ki->iocb.ki_flags = IOCB_DIRECT;
112 ki->iocb.ki_hint = ki_hint_validate(file_write_hint(file));
113 ki->iocb.ki_ioprio = get_current_ioprio();
114 ki->skipped = skipped;
115 ki->term_func = term_func;
116 ki->term_func_priv = term_func_priv;
117 ki->was_async = true;
118
119 if (ki->term_func)
120 ki->iocb.ki_complete = cachefiles_read_complete;
121
122 get_file(ki->iocb.ki_filp);
123
124 old_nofs = memalloc_nofs_save();
125 ret = vfs_iocb_iter_read(file, &ki->iocb, iter);
126 memalloc_nofs_restore(old_nofs);
127 switch (ret) {
128 case -EIOCBQUEUED:
129 goto in_progress;
130
131 case -ERESTARTSYS:
132 case -ERESTARTNOINTR:
133 case -ERESTARTNOHAND:
134 case -ERESTART_RESTARTBLOCK:
135 /* There's no easy way to restart the syscall since other AIO's
136 * may be already running. Just fail this IO with EINTR.
137 */
138 ret = -EINTR;
139 fallthrough;
140 default:
141 ki->was_async = false;
142 cachefiles_read_complete(&ki->iocb, ret, 0);
143 if (ret > 0)
144 ret = 0;
145 break;
146 }
147
148in_progress:
149 cachefiles_put_kiocb(ki);
150 _leave(" = %zd", ret);
151 return ret;
152
153presubmission_error:
154 if (term_func)
155 term_func(term_func_priv, ret < 0 ? ret : skipped, false);
156 return ret;
157}
158
159/*
160 * Handle completion of a write to the cache.
161 */
162static void cachefiles_write_complete(struct kiocb *iocb, long ret, long ret2)
163{
164 struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
165 struct inode *inode = file_inode(ki->iocb.ki_filp);
166
167 _enter("%ld,%ld", ret, ret2);
168
169 /* Tell lockdep we inherited freeze protection from submission thread */
170 __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
171 __sb_end_write(inode->i_sb, SB_FREEZE_WRITE);
172
173 if (ki->term_func)
174 ki->term_func(ki->term_func_priv, ret, ki->was_async);
175
176 cachefiles_put_kiocb(ki);
177}
178
179/*
180 * Initiate a write to the cache.
181 */
182static int cachefiles_write(struct netfs_cache_resources *cres,
183 loff_t start_pos,
184 struct iov_iter *iter,
185 netfs_io_terminated_t term_func,
186 void *term_func_priv)
187{
188 struct cachefiles_kiocb *ki;
189 struct inode *inode;
190 struct file *file = cres->cache_priv2;
191 unsigned int old_nofs;
192 ssize_t ret = -ENOBUFS;
193 size_t len = iov_iter_count(iter);
194
195 _enter("%pD,%li,%llx,%zx/%llx",
196 file, file_inode(file)->i_ino, start_pos, len,
197 i_size_read(file->f_inode));
198
199 ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
200 if (!ki)
201 goto presubmission_error;
202
203 refcount_set(&ki->ki_refcnt, 2);
204 ki->iocb.ki_filp = file;
205 ki->iocb.ki_pos = start_pos;
206 ki->iocb.ki_flags = IOCB_DIRECT | IOCB_WRITE;
207 ki->iocb.ki_hint = ki_hint_validate(file_write_hint(file));
208 ki->iocb.ki_ioprio = get_current_ioprio();
209 ki->start = start_pos;
210 ki->len = len;
211 ki->term_func = term_func;
212 ki->term_func_priv = term_func_priv;
213 ki->was_async = true;
214
215 if (ki->term_func)
216 ki->iocb.ki_complete = cachefiles_write_complete;
217
218 /* Open-code file_start_write here to grab freeze protection, which
219 * will be released by another thread in aio_complete_rw(). Fool
220 * lockdep by telling it the lock got released so that it doesn't
221 * complain about the held lock when we return to userspace.
222 */
223 inode = file_inode(file);
224 __sb_start_write(inode->i_sb, SB_FREEZE_WRITE);
225 __sb_writers_release(inode->i_sb, SB_FREEZE_WRITE);
226
227 get_file(ki->iocb.ki_filp);
228
229 old_nofs = memalloc_nofs_save();
230 ret = vfs_iocb_iter_write(file, &ki->iocb, iter);
231 memalloc_nofs_restore(old_nofs);
232 switch (ret) {
233 case -EIOCBQUEUED:
234 goto in_progress;
235
236 case -ERESTARTSYS:
237 case -ERESTARTNOINTR:
238 case -ERESTARTNOHAND:
239 case -ERESTART_RESTARTBLOCK:
240 /* There's no easy way to restart the syscall since other AIO's
241 * may be already running. Just fail this IO with EINTR.
242 */
243 ret = -EINTR;
244 fallthrough;
245 default:
246 ki->was_async = false;
247 cachefiles_write_complete(&ki->iocb, ret, 0);
248 if (ret > 0)
249 ret = 0;
250 break;
251 }
252
253in_progress:
254 cachefiles_put_kiocb(ki);
255 _leave(" = %zd", ret);
256 return ret;
257
258presubmission_error:
259 if (term_func)
260 term_func(term_func_priv, -ENOMEM, false);
261 return -ENOMEM;
262}
263
264/*
265 * Prepare a read operation, shortening it to a cached/uncached
266 * boundary as appropriate.
267 */
268static enum netfs_read_source cachefiles_prepare_read(struct netfs_read_subrequest *subreq,
269 loff_t i_size)
270{
271 struct fscache_retrieval *op = subreq->rreq->cache_resources.cache_priv;
272 struct cachefiles_object *object;
273 struct cachefiles_cache *cache;
274 const struct cred *saved_cred;
275 struct file *file = subreq->rreq->cache_resources.cache_priv2;
276 loff_t off, to;
277
278 _enter("%zx @%llx/%llx", subreq->len, subreq->start, i_size);
279
280 object = container_of(op->op.object,
281 struct cachefiles_object, fscache);
282 cache = container_of(object->fscache.cache,
283 struct cachefiles_cache, cache);
284
285 if (!file)
286 goto cache_fail_nosec;
287
288 if (subreq->start >= i_size)
289 return NETFS_FILL_WITH_ZEROES;
290
291 cachefiles_begin_secure(cache, &saved_cred);
292
293 off = vfs_llseek(file, subreq->start, SEEK_DATA);
294 if (off < 0 && off >= (loff_t)-MAX_ERRNO) {
295 if (off == (loff_t)-ENXIO)
296 goto download_and_store;
297 goto cache_fail;
298 }
299
300 if (off >= subreq->start + subreq->len)
301 goto download_and_store;
302
303 if (off > subreq->start) {
304 off = round_up(off, cache->bsize);
305 subreq->len = off - subreq->start;
306 goto download_and_store;
307 }
308
309 to = vfs_llseek(file, subreq->start, SEEK_HOLE);
310 if (to < 0 && to >= (loff_t)-MAX_ERRNO)
311 goto cache_fail;
312
313 if (to < subreq->start + subreq->len) {
314 if (subreq->start + subreq->len >= i_size)
315 to = round_up(to, cache->bsize);
316 else
317 to = round_down(to, cache->bsize);
318 subreq->len = to - subreq->start;
319 }
320
321 cachefiles_end_secure(cache, saved_cred);
322 return NETFS_READ_FROM_CACHE;
323
324download_and_store:
325 if (cachefiles_has_space(cache, 0, (subreq->len + PAGE_SIZE - 1) / PAGE_SIZE) == 0)
326 __set_bit(NETFS_SREQ_WRITE_TO_CACHE, &subreq->flags);
327cache_fail:
328 cachefiles_end_secure(cache, saved_cred);
329cache_fail_nosec:
330 return NETFS_DOWNLOAD_FROM_SERVER;
331}
332
333/*
334 * Prepare for a write to occur.
335 */
336static int cachefiles_prepare_write(struct netfs_cache_resources *cres,
337 loff_t *_start, size_t *_len, loff_t i_size)
338{
339 loff_t start = *_start;
340 size_t len = *_len, down;
341
342 /* Round to DIO size */
343 down = start - round_down(start, PAGE_SIZE);
344 *_start = start - down;
345 *_len = round_up(down + len, PAGE_SIZE);
346 return 0;
347}
348
349/*
350 * Clean up an operation.
351 */
352static void cachefiles_end_operation(struct netfs_cache_resources *cres)
353{
354 struct fscache_retrieval *op = cres->cache_priv;
355 struct file *file = cres->cache_priv2;
356
357 _enter("");
358
359 if (file)
360 fput(file);
361 if (op) {
362 fscache_op_complete(&op->op, false);
363 fscache_put_retrieval(op);
364 }
365
366 _leave("");
367}
368
369static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
370 .end_operation = cachefiles_end_operation,
371 .read = cachefiles_read,
372 .write = cachefiles_write,
373 .prepare_read = cachefiles_prepare_read,
374 .prepare_write = cachefiles_prepare_write,
375};
376
377/*
378 * Open the cache file when beginning a cache operation.
379 */
380int cachefiles_begin_read_operation(struct netfs_read_request *rreq,
381 struct fscache_retrieval *op)
382{
383 struct cachefiles_object *object;
384 struct cachefiles_cache *cache;
385 struct path path;
386 struct file *file;
387
388 _enter("");
389
390 object = container_of(op->op.object,
391 struct cachefiles_object, fscache);
392 cache = container_of(object->fscache.cache,
393 struct cachefiles_cache, cache);
394
395 path.mnt = cache->mnt;
396 path.dentry = object->backer;
397 file = open_with_fake_path(&path, O_RDWR | O_LARGEFILE | O_DIRECT,
398 d_inode(object->backer), cache->cache_cred);
399 if (IS_ERR(file))
400 return PTR_ERR(file);
401 if (!S_ISREG(file_inode(file)->i_mode))
402 goto error_file;
403 if (unlikely(!file->f_op->read_iter) ||
404 unlikely(!file->f_op->write_iter)) {
405 pr_notice("Cache does not support read_iter and write_iter\n");
406 goto error_file;
407 }
408
409 fscache_get_retrieval(op);
410 rreq->cache_resources.cache_priv = op;
411 rreq->cache_resources.cache_priv2 = file;
412 rreq->cache_resources.ops = &cachefiles_netfs_cache_ops;
413 rreq->cookie_debug_id = object->fscache.debug_id;
414 _leave("");
415 return 0;
416
417error_file:
418 fput(file);
419 return -EIO;
420}