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/bio.h>
13#include <linux/falloc.h>
14#include <linux/sched/mm.h>
15#include <trace/events/fscache.h>
16#include <trace/events/netfs.h>
17#include "internal.h"
18
19struct cachefiles_kiocb {
20 struct kiocb iocb;
21 refcount_t ki_refcnt;
22 loff_t start;
23 union {
24 size_t skipped;
25 size_t len;
26 };
27 struct cachefiles_object *object;
28 netfs_io_terminated_t term_func;
29 void *term_func_priv;
30 bool was_async;
31 unsigned int inval_counter; /* Copy of cookie->inval_counter */
32 u64 b_writing;
33};
34
35static inline void cachefiles_put_kiocb(struct cachefiles_kiocb *ki)
36{
37 if (refcount_dec_and_test(r: &ki->ki_refcnt)) {
38 cachefiles_put_object(object: ki->object, why: cachefiles_obj_put_ioreq);
39 fput(ki->iocb.ki_filp);
40 kfree(objp: ki);
41 }
42}
43
44/*
45 * Handle completion of a read from the cache.
46 */
47static void cachefiles_read_complete(struct kiocb *iocb, long ret)
48{
49 struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
50 struct inode *inode = file_inode(f: ki->iocb.ki_filp);
51
52 _enter("%ld", ret);
53
54 if (ret < 0)
55 trace_cachefiles_io_error(obj: ki->object, backer: inode, error: ret,
56 where: cachefiles_trace_read_error);
57
58 if (ki->term_func) {
59 if (ret >= 0) {
60 if (ki->object->cookie->inval_counter == ki->inval_counter)
61 ki->skipped += ret;
62 else
63 ret = -ESTALE;
64 }
65
66 ki->term_func(ki->term_func_priv, ret);
67 }
68
69 cachefiles_put_kiocb(ki);
70}
71
72/*
73 * Initiate a read from the cache.
74 */
75static int cachefiles_read(struct netfs_cache_resources *cres,
76 loff_t start_pos,
77 struct iov_iter *iter,
78 enum netfs_read_from_hole read_hole,
79 netfs_io_terminated_t term_func,
80 void *term_func_priv)
81{
82 struct cachefiles_object *object;
83 struct cachefiles_kiocb *ki;
84 struct file *file;
85 unsigned int old_nofs;
86 ssize_t ret = -ENOBUFS;
87 size_t len = iov_iter_count(i: iter), skipped = 0;
88
89 if (!fscache_wait_for_operation(cred: cres, state: FSCACHE_WANT_READ))
90 goto presubmission_error;
91
92 fscache_count_read();
93 object = cachefiles_cres_object(cres);
94 file = cachefiles_cres_file(cres);
95
96 _enter("%pD,%li,%llx,%zx/%llx",
97 file, file_inode(file)->i_ino, start_pos, len,
98 i_size_read(file_inode(file)));
99
100 /* If the caller asked us to seek for data before doing the read, then
101 * we should do that now. If we find a gap, we fill it with zeros.
102 */
103 if (read_hole != NETFS_READ_HOLE_IGNORE) {
104 loff_t off = start_pos, off2;
105
106 off2 = cachefiles_inject_read_error();
107 if (off2 == 0)
108 off2 = vfs_llseek(file, offset: off, SEEK_DATA);
109 if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO && off2 != -ENXIO) {
110 skipped = 0;
111 ret = off2;
112 goto presubmission_error;
113 }
114
115 if (off2 == -ENXIO || off2 >= start_pos + len) {
116 /* The region is beyond the EOF or there's no more data
117 * in the region, so clear the rest of the buffer and
118 * return success.
119 */
120 ret = -ENODATA;
121 if (read_hole == NETFS_READ_HOLE_FAIL)
122 goto presubmission_error;
123
124 iov_iter_zero(bytes: len, iter);
125 skipped = len;
126 ret = 0;
127 goto presubmission_error;
128 }
129
130 skipped = off2 - off;
131 iov_iter_zero(bytes: skipped, iter);
132 }
133
134 ret = -ENOMEM;
135 ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
136 if (!ki)
137 goto presubmission_error;
138
139 refcount_set(r: &ki->ki_refcnt, n: 2);
140 ki->iocb.ki_filp = file;
141 ki->iocb.ki_pos = start_pos + skipped;
142 ki->iocb.ki_flags = IOCB_DIRECT;
143 ki->iocb.ki_ioprio = get_current_ioprio();
144 ki->skipped = skipped;
145 ki->object = object;
146 ki->inval_counter = cres->inval_counter;
147 ki->term_func = term_func;
148 ki->term_func_priv = term_func_priv;
149 ki->was_async = true;
150
151 if (ki->term_func)
152 ki->iocb.ki_complete = cachefiles_read_complete;
153
154 get_file(f: ki->iocb.ki_filp);
155 cachefiles_grab_object(object, why: cachefiles_obj_get_ioreq);
156
157 trace_cachefiles_read(obj: object, backer: file_inode(f: file), start: ki->iocb.ki_pos, len: len - skipped);
158 old_nofs = memalloc_nofs_save();
159 ret = cachefiles_inject_read_error();
160 if (ret == 0)
161 ret = vfs_iocb_iter_read(file, iocb: &ki->iocb, iter);
162 memalloc_nofs_restore(flags: old_nofs);
163 switch (ret) {
164 case -EIOCBQUEUED:
165 goto in_progress;
166
167 case -ERESTARTSYS:
168 case -ERESTARTNOINTR:
169 case -ERESTARTNOHAND:
170 case -ERESTART_RESTARTBLOCK:
171 /* There's no easy way to restart the syscall since other AIO's
172 * may be already running. Just fail this IO with EINTR.
173 */
174 ret = -EINTR;
175 fallthrough;
176 default:
177 ki->was_async = false;
178 cachefiles_read_complete(iocb: &ki->iocb, ret);
179 if (ret > 0)
180 ret = 0;
181 break;
182 }
183
184in_progress:
185 cachefiles_put_kiocb(ki);
186 _leave(" = %zd", ret);
187 return ret;
188
189presubmission_error:
190 if (term_func)
191 term_func(term_func_priv, ret < 0 ? ret : skipped);
192 return ret;
193}
194
195/*
196 * Query the occupancy of the cache in a region, returning where the next chunk
197 * of data starts and how long it is.
198 */
199static int cachefiles_query_occupancy(struct netfs_cache_resources *cres,
200 loff_t start, size_t len, size_t granularity,
201 loff_t *_data_start, size_t *_data_len)
202{
203 struct cachefiles_object *object;
204 struct file *file;
205 loff_t off, off2;
206
207 *_data_start = -1;
208 *_data_len = 0;
209
210 if (!fscache_wait_for_operation(cred: cres, state: FSCACHE_WANT_READ))
211 return -ENOBUFS;
212
213 object = cachefiles_cres_object(cres);
214 file = cachefiles_cres_file(cres);
215 granularity = max_t(size_t, object->volume->cache->bsize, granularity);
216
217 _enter("%pD,%li,%llx,%zx/%llx",
218 file, file_inode(file)->i_ino, start, len,
219 i_size_read(file_inode(file)));
220
221 off = cachefiles_inject_read_error();
222 if (off == 0)
223 off = vfs_llseek(file, offset: start, SEEK_DATA);
224 if (off == -ENXIO)
225 return -ENODATA; /* Beyond EOF */
226 if (off < 0 && off >= (loff_t)-MAX_ERRNO)
227 return -ENOBUFS; /* Error. */
228 if (round_up(off, granularity) >= start + len)
229 return -ENODATA; /* No data in range */
230
231 off2 = cachefiles_inject_read_error();
232 if (off2 == 0)
233 off2 = vfs_llseek(file, offset: off, SEEK_HOLE);
234 if (off2 == -ENXIO)
235 return -ENODATA; /* Beyond EOF */
236 if (off2 < 0 && off2 >= (loff_t)-MAX_ERRNO)
237 return -ENOBUFS; /* Error. */
238
239 /* Round away partial blocks */
240 off = round_up(off, granularity);
241 off2 = round_down(off2, granularity);
242 if (off2 <= off)
243 return -ENODATA;
244
245 *_data_start = off;
246 if (off2 > start + len)
247 *_data_len = len;
248 else
249 *_data_len = off2 - off;
250 return 0;
251}
252
253/*
254 * Handle completion of a write to the cache.
255 */
256static void cachefiles_write_complete(struct kiocb *iocb, long ret)
257{
258 struct cachefiles_kiocb *ki = container_of(iocb, struct cachefiles_kiocb, iocb);
259 struct cachefiles_object *object = ki->object;
260 struct inode *inode = file_inode(f: ki->iocb.ki_filp);
261
262 _enter("%ld", ret);
263
264 if (ki->was_async)
265 kiocb_end_write(iocb);
266
267 if (ret < 0)
268 trace_cachefiles_io_error(obj: object, backer: inode, error: ret,
269 where: cachefiles_trace_write_error);
270
271 atomic_long_sub(i: ki->b_writing, v: &object->volume->cache->b_writing);
272 set_bit(FSCACHE_COOKIE_HAVE_DATA, addr: &object->cookie->flags);
273 if (ki->term_func)
274 ki->term_func(ki->term_func_priv, ret);
275 cachefiles_put_kiocb(ki);
276}
277
278/*
279 * Initiate a write to the cache.
280 */
281int __cachefiles_write(struct cachefiles_object *object,
282 struct file *file,
283 loff_t start_pos,
284 struct iov_iter *iter,
285 netfs_io_terminated_t term_func,
286 void *term_func_priv)
287{
288 struct cachefiles_cache *cache;
289 struct cachefiles_kiocb *ki;
290 unsigned int old_nofs;
291 ssize_t ret;
292 size_t len = iov_iter_count(i: iter);
293
294 fscache_count_write();
295 cache = object->volume->cache;
296
297 _enter("%pD,%li,%llx,%zx/%llx",
298 file, file_inode(file)->i_ino, start_pos, len,
299 i_size_read(file_inode(file)));
300
301 ki = kzalloc(sizeof(struct cachefiles_kiocb), GFP_KERNEL);
302 if (!ki) {
303 if (term_func)
304 term_func(term_func_priv, -ENOMEM);
305 return -ENOMEM;
306 }
307
308 refcount_set(r: &ki->ki_refcnt, n: 2);
309 ki->iocb.ki_filp = file;
310 ki->iocb.ki_pos = start_pos;
311 ki->iocb.ki_flags = IOCB_DIRECT | IOCB_WRITE;
312 ki->iocb.ki_ioprio = get_current_ioprio();
313 ki->object = object;
314 ki->start = start_pos;
315 ki->len = len;
316 ki->term_func = term_func;
317 ki->term_func_priv = term_func_priv;
318 ki->was_async = true;
319 ki->b_writing = (len + (1 << cache->bshift) - 1) >> cache->bshift;
320
321 if (ki->term_func)
322 ki->iocb.ki_complete = cachefiles_write_complete;
323 atomic_long_add(i: ki->b_writing, v: &cache->b_writing);
324
325 get_file(f: ki->iocb.ki_filp);
326 cachefiles_grab_object(object, why: cachefiles_obj_get_ioreq);
327
328 trace_cachefiles_write(obj: object, backer: file_inode(f: file), start: ki->iocb.ki_pos, len);
329 old_nofs = memalloc_nofs_save();
330 ret = cachefiles_inject_write_error();
331 if (ret == 0)
332 ret = vfs_iocb_iter_write(file, iocb: &ki->iocb, iter);
333 memalloc_nofs_restore(flags: old_nofs);
334 switch (ret) {
335 case -EIOCBQUEUED:
336 goto in_progress;
337
338 case -ERESTARTSYS:
339 case -ERESTARTNOINTR:
340 case -ERESTARTNOHAND:
341 case -ERESTART_RESTARTBLOCK:
342 /* There's no easy way to restart the syscall since other AIO's
343 * may be already running. Just fail this IO with EINTR.
344 */
345 ret = -EINTR;
346 fallthrough;
347 default:
348 ki->was_async = false;
349 cachefiles_write_complete(iocb: &ki->iocb, ret);
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(cred: cres, state: FSCACHE_WANT_WRITE)) {
366 if (term_func)
367 term_func(term_func_priv, -ENOBUFS);
368 trace_netfs_sreq(sreq: term_func_priv, what: netfs_sreq_trace_cache_nowrite);
369 return -ENOBUFS;
370 }
371
372 return __cachefiles_write(object: cachefiles_cres_object(cres),
373 file: cachefiles_cres_file(cres),
374 start_pos, iter,
375 term_func, term_func_priv);
376}
377
378static inline enum netfs_io_source
379cachefiles_do_prepare_read(struct netfs_cache_resources *cres,
380 loff_t start, size_t *_len, loff_t i_size,
381 unsigned long *_flags, ino_t netfs_ino)
382{
383 enum cachefiles_prepare_read_trace why;
384 struct cachefiles_object *object = NULL;
385 struct cachefiles_cache *cache;
386 struct fscache_cookie *cookie = fscache_cres_cookie(cres);
387 const struct cred *saved_cred;
388 struct file *file = cachefiles_cres_file(cres);
389 enum netfs_io_source ret = NETFS_DOWNLOAD_FROM_SERVER;
390 size_t len = *_len;
391 loff_t off, to;
392 ino_t ino = file ? file_inode(f: file)->i_ino : 0;
393 int rc;
394
395 _enter("%zx @%llx/%llx", len, start, i_size);
396
397 if (start >= i_size) {
398 ret = NETFS_FILL_WITH_ZEROES;
399 why = cachefiles_trace_read_after_eof;
400 goto out_no_object;
401 }
402
403 if (test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags)) {
404 __set_bit(NETFS_SREQ_COPY_TO_CACHE, _flags);
405 why = cachefiles_trace_read_no_data;
406 if (!test_bit(NETFS_SREQ_ONDEMAND, _flags))
407 goto out_no_object;
408 }
409
410 /* The object and the file may be being created in the background. */
411 if (!file) {
412 why = cachefiles_trace_read_no_file;
413 if (!fscache_wait_for_operation(cred: cres, state: FSCACHE_WANT_READ))
414 goto out_no_object;
415 file = cachefiles_cres_file(cres);
416 if (!file)
417 goto out_no_object;
418 ino = file_inode(f: file)->i_ino;
419 }
420
421 object = cachefiles_cres_object(cres);
422 cache = object->volume->cache;
423 cachefiles_begin_secure(cache, saved_cred: &saved_cred);
424retry:
425 off = cachefiles_inject_read_error();
426 if (off == 0)
427 off = vfs_llseek(file, offset: start, SEEK_DATA);
428 if (off < 0 && off >= (loff_t)-MAX_ERRNO) {
429 if (off == (loff_t)-ENXIO) {
430 why = cachefiles_trace_read_seek_nxio;
431 goto download_and_store;
432 }
433 trace_cachefiles_io_error(obj: object, backer: file_inode(f: file), error: off,
434 where: cachefiles_trace_seek_error);
435 why = cachefiles_trace_read_seek_error;
436 goto out;
437 }
438
439 if (off >= start + len) {
440 why = cachefiles_trace_read_found_hole;
441 goto download_and_store;
442 }
443
444 if (off > start) {
445 off = round_up(off, cache->bsize);
446 len = off - start;
447 *_len = len;
448 why = cachefiles_trace_read_found_part;
449 goto download_and_store;
450 }
451
452 to = cachefiles_inject_read_error();
453 if (to == 0)
454 to = vfs_llseek(file, offset: start, SEEK_HOLE);
455 if (to < 0 && to >= (loff_t)-MAX_ERRNO) {
456 trace_cachefiles_io_error(obj: object, backer: file_inode(f: file), error: to,
457 where: cachefiles_trace_seek_error);
458 why = cachefiles_trace_read_seek_error;
459 goto out;
460 }
461
462 if (to < start + len) {
463 if (start + len >= i_size)
464 to = round_up(to, cache->bsize);
465 else
466 to = round_down(to, cache->bsize);
467 len = to - start;
468 *_len = len;
469 }
470
471 why = cachefiles_trace_read_have_data;
472 ret = NETFS_READ_FROM_CACHE;
473 goto out;
474
475download_and_store:
476 __set_bit(NETFS_SREQ_COPY_TO_CACHE, _flags);
477 if (test_bit(NETFS_SREQ_ONDEMAND, _flags)) {
478 rc = cachefiles_ondemand_read(object, pos: start, len);
479 if (!rc) {
480 __clear_bit(NETFS_SREQ_ONDEMAND, _flags);
481 goto retry;
482 }
483 ret = NETFS_INVALID_READ;
484 }
485out:
486 cachefiles_end_secure(cache, saved_cred);
487out_no_object:
488 trace_cachefiles_prep_read(obj: object, start, len, flags: *_flags, source: ret, why, cache_inode: ino, netfs_inode: netfs_ino);
489 return ret;
490}
491
492/*
493 * Prepare a read operation, shortening it to a cached/uncached
494 * boundary as appropriate.
495 */
496static enum netfs_io_source cachefiles_prepare_read(struct netfs_io_subrequest *subreq,
497 unsigned long long i_size)
498{
499 return cachefiles_do_prepare_read(cres: &subreq->rreq->cache_resources,
500 start: subreq->start, len: &subreq->len, i_size,
501 flags: &subreq->flags, netfs_ino: subreq->rreq->inode->i_ino);
502}
503
504/*
505 * Prepare an on-demand read operation, shortening it to a cached/uncached
506 * boundary as appropriate.
507 */
508static enum netfs_io_source
509cachefiles_prepare_ondemand_read(struct netfs_cache_resources *cres,
510 loff_t start, size_t *_len, loff_t i_size,
511 unsigned long *_flags, ino_t ino)
512{
513 return cachefiles_do_prepare_read(cres, start, _len, i_size, _flags, netfs_ino: ino);
514}
515
516/*
517 * Prepare for a write to occur.
518 */
519int __cachefiles_prepare_write(struct cachefiles_object *object,
520 struct file *file,
521 loff_t *_start, size_t *_len, size_t upper_len,
522 bool no_space_allocated_yet)
523{
524 struct cachefiles_cache *cache = object->volume->cache;
525 loff_t start = *_start, pos;
526 size_t len = *_len;
527 int ret;
528
529 /* Round to DIO size */
530 start = round_down(*_start, PAGE_SIZE);
531 if (start != *_start || *_len > upper_len) {
532 /* Probably asked to cache a streaming write written into the
533 * pagecache when the cookie was temporarily out of service to
534 * culling.
535 */
536 fscache_count_dio_misfit();
537 return -ENOBUFS;
538 }
539
540 *_len = round_up(len, PAGE_SIZE);
541
542 /* We need to work out whether there's sufficient disk space to perform
543 * the write - but we can skip that check if we have space already
544 * allocated.
545 */
546 if (no_space_allocated_yet)
547 goto check_space;
548
549 pos = cachefiles_inject_read_error();
550 if (pos == 0)
551 pos = vfs_llseek(file, offset: start, SEEK_DATA);
552 if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
553 if (pos == -ENXIO)
554 goto check_space; /* Unallocated tail */
555 trace_cachefiles_io_error(obj: object, backer: file_inode(f: file), error: pos,
556 where: cachefiles_trace_seek_error);
557 return pos;
558 }
559 if ((u64)pos >= (u64)start + *_len)
560 goto check_space; /* Unallocated region */
561
562 /* We have a block that's at least partially filled - if we're low on
563 * space, we need to see if it's fully allocated. If it's not, we may
564 * want to cull it.
565 */
566 if (cachefiles_has_space(cache, fnr: 0, bnr: *_len / PAGE_SIZE,
567 reason: cachefiles_has_space_check) == 0)
568 return 0; /* Enough space to simply overwrite the whole block */
569
570 pos = cachefiles_inject_read_error();
571 if (pos == 0)
572 pos = vfs_llseek(file, offset: start, SEEK_HOLE);
573 if (pos < 0 && pos >= (loff_t)-MAX_ERRNO) {
574 trace_cachefiles_io_error(obj: object, backer: file_inode(f: file), error: pos,
575 where: cachefiles_trace_seek_error);
576 return pos;
577 }
578 if ((u64)pos >= (u64)start + *_len)
579 return 0; /* Fully allocated */
580
581 /* Partially allocated, but insufficient space: cull. */
582 fscache_count_no_write_space();
583 ret = cachefiles_inject_remove_error();
584 if (ret == 0)
585 ret = vfs_fallocate(file, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
586 offset: start, len: *_len);
587 if (ret < 0) {
588 trace_cachefiles_io_error(obj: object, backer: file_inode(f: file), error: ret,
589 where: cachefiles_trace_fallocate_error);
590 cachefiles_io_error_obj(object,
591 "CacheFiles: fallocate failed (%d)\n", ret);
592 ret = -EIO;
593 }
594
595 return ret;
596
597check_space:
598 return cachefiles_has_space(cache, fnr: 0, bnr: *_len / PAGE_SIZE,
599 reason: cachefiles_has_space_for_write);
600}
601
602static int cachefiles_prepare_write(struct netfs_cache_resources *cres,
603 loff_t *_start, size_t *_len, size_t upper_len,
604 loff_t i_size, bool no_space_allocated_yet)
605{
606 struct cachefiles_object *object = cachefiles_cres_object(cres);
607 struct cachefiles_cache *cache = object->volume->cache;
608 const struct cred *saved_cred;
609 int ret;
610
611 if (!cachefiles_cres_file(cres)) {
612 if (!fscache_wait_for_operation(cred: cres, state: FSCACHE_WANT_WRITE))
613 return -ENOBUFS;
614 if (!cachefiles_cres_file(cres))
615 return -ENOBUFS;
616 }
617
618 cachefiles_begin_secure(cache, saved_cred: &saved_cred);
619 ret = __cachefiles_prepare_write(object, file: cachefiles_cres_file(cres),
620 _start, _len, upper_len,
621 no_space_allocated_yet);
622 cachefiles_end_secure(cache, saved_cred);
623 return ret;
624}
625
626static void cachefiles_prepare_write_subreq(struct netfs_io_subrequest *subreq)
627{
628 struct netfs_io_request *wreq = subreq->rreq;
629 struct netfs_cache_resources *cres = &wreq->cache_resources;
630 struct netfs_io_stream *stream = &wreq->io_streams[subreq->stream_nr];
631
632 _enter("W=%x[%x] %llx", wreq->debug_id, subreq->debug_index, subreq->start);
633
634 stream->sreq_max_len = MAX_RW_COUNT;
635 stream->sreq_max_segs = BIO_MAX_VECS;
636
637 if (!cachefiles_cres_file(cres)) {
638 if (!fscache_wait_for_operation(cred: cres, state: FSCACHE_WANT_WRITE))
639 return netfs_prepare_write_failed(subreq);
640 if (!cachefiles_cres_file(cres))
641 return netfs_prepare_write_failed(subreq);
642 }
643}
644
645static void cachefiles_issue_write(struct netfs_io_subrequest *subreq)
646{
647 struct netfs_io_request *wreq = subreq->rreq;
648 struct netfs_cache_resources *cres = &wreq->cache_resources;
649 struct cachefiles_object *object = cachefiles_cres_object(cres);
650 struct cachefiles_cache *cache = object->volume->cache;
651 struct netfs_io_stream *stream = &wreq->io_streams[subreq->stream_nr];
652 const struct cred *saved_cred;
653 size_t off, pre, post, len = subreq->len;
654 loff_t start = subreq->start;
655 int ret;
656
657 _enter("W=%x[%x] %llx-%llx",
658 wreq->debug_id, subreq->debug_index, start, start + len - 1);
659
660 /* We need to start on the cache granularity boundary */
661 off = start & (CACHEFILES_DIO_BLOCK_SIZE - 1);
662 if (off) {
663 pre = CACHEFILES_DIO_BLOCK_SIZE - off;
664 if (pre >= len) {
665 fscache_count_dio_misfit();
666 netfs_write_subrequest_terminated(op: subreq, transferred_or_error: len);
667 return;
668 }
669 subreq->transferred += pre;
670 start += pre;
671 len -= pre;
672 iov_iter_advance(i: &subreq->io_iter, bytes: pre);
673 }
674
675 /* We also need to end on the cache granularity boundary */
676 if (start + len == wreq->i_size) {
677 size_t part = len % CACHEFILES_DIO_BLOCK_SIZE;
678 size_t need = CACHEFILES_DIO_BLOCK_SIZE - part;
679
680 if (part && stream->submit_extendable_to >= need) {
681 len += need;
682 subreq->len += need;
683 subreq->io_iter.count += need;
684 }
685 }
686
687 post = len & (CACHEFILES_DIO_BLOCK_SIZE - 1);
688 if (post) {
689 len -= post;
690 if (len == 0) {
691 fscache_count_dio_misfit();
692 netfs_write_subrequest_terminated(op: subreq, transferred_or_error: post);
693 return;
694 }
695 iov_iter_truncate(i: &subreq->io_iter, count: len);
696 }
697
698 trace_netfs_sreq(sreq: subreq, what: netfs_sreq_trace_cache_prepare);
699 cachefiles_begin_secure(cache, saved_cred: &saved_cred);
700 ret = __cachefiles_prepare_write(object, file: cachefiles_cres_file(cres),
701 start: &start, len: &len, upper_len: len, no_space_allocated_yet: true);
702 cachefiles_end_secure(cache, saved_cred);
703 if (ret < 0) {
704 netfs_write_subrequest_terminated(op: subreq, transferred_or_error: ret);
705 return;
706 }
707
708 trace_netfs_sreq(sreq: subreq, what: netfs_sreq_trace_cache_write);
709 cachefiles_write(cres: &subreq->rreq->cache_resources,
710 start_pos: subreq->start, iter: &subreq->io_iter,
711 term_func: netfs_write_subrequest_terminated, term_func_priv: subreq);
712}
713
714/*
715 * Clean up an operation.
716 */
717static void cachefiles_end_operation(struct netfs_cache_resources *cres)
718{
719 struct file *file = cachefiles_cres_file(cres);
720
721 if (file)
722 fput(file);
723 fscache_end_cookie_access(cookie: fscache_cres_cookie(cres), why: fscache_access_io_end);
724}
725
726static const struct netfs_cache_ops cachefiles_netfs_cache_ops = {
727 .end_operation = cachefiles_end_operation,
728 .read = cachefiles_read,
729 .write = cachefiles_write,
730 .issue_write = cachefiles_issue_write,
731 .prepare_read = cachefiles_prepare_read,
732 .prepare_write = cachefiles_prepare_write,
733 .prepare_write_subreq = cachefiles_prepare_write_subreq,
734 .prepare_ondemand_read = cachefiles_prepare_ondemand_read,
735 .query_occupancy = cachefiles_query_occupancy,
736};
737
738/*
739 * Open the cache file when beginning a cache operation.
740 */
741bool cachefiles_begin_operation(struct netfs_cache_resources *cres,
742 enum fscache_want_state want_state)
743{
744 struct cachefiles_object *object = cachefiles_cres_object(cres);
745
746 if (!cachefiles_cres_file(cres)) {
747 cres->ops = &cachefiles_netfs_cache_ops;
748 if (object->file) {
749 spin_lock(lock: &object->lock);
750 if (!cres->cache_priv2 && object->file)
751 cres->cache_priv2 = get_file(f: object->file);
752 spin_unlock(lock: &object->lock);
753 }
754 }
755
756 if (!cachefiles_cres_file(cres) && want_state != FSCACHE_WANT_PARAMS) {
757 pr_err("failed to get cres->file\n");
758 return false;
759 }
760
761 return true;
762}
763

source code of linux/fs/cachefiles/io.c