1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Network filesystem support services.
3 *
4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
6 *
7 * See:
8 *
9 * Documentation/filesystems/netfs_library.rst
10 *
11 * for a description of the network filesystem interface declared here.
12 */
13
14 #ifndef _LINUX_NETFS_H
15 #define _LINUX_NETFS_H
16
17 #include <linux/workqueue.h>
18 #include <linux/fs.h>
19 #include <linux/pagemap.h>
20 #include <linux/uio.h>
21
22 enum netfs_sreq_ref_trace;
23 typedef struct mempool_s mempool_t;
24
25 /**
26 * folio_start_private_2 - Start an fscache write on a folio. [DEPRECATED]
27 * @folio: The folio.
28 *
29 * Call this function before writing a folio to a local cache. Starting a
30 * second write before the first one finishes is not allowed.
31 *
32 * Note that this should no longer be used.
33 */
folio_start_private_2(struct folio * folio)34 static inline void folio_start_private_2(struct folio *folio)
35 {
36 VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
37 folio_get(folio);
38 folio_set_private_2(folio);
39 }
40
41 enum netfs_io_source {
42 NETFS_SOURCE_UNKNOWN,
43 NETFS_FILL_WITH_ZEROES,
44 NETFS_DOWNLOAD_FROM_SERVER,
45 NETFS_READ_FROM_CACHE,
46 NETFS_INVALID_READ,
47 NETFS_UPLOAD_TO_SERVER,
48 NETFS_WRITE_TO_CACHE,
49 NETFS_INVALID_WRITE,
50 } __mode(byte);
51
52 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
53 bool was_async);
54
55 /*
56 * Per-inode context. This wraps the VFS inode.
57 */
58 struct netfs_inode {
59 struct inode inode; /* The VFS inode */
60 const struct netfs_request_ops *ops;
61 #if IS_ENABLED(CONFIG_FSCACHE)
62 struct fscache_cookie *cache;
63 #endif
64 struct mutex wb_lock; /* Writeback serialisation */
65 loff_t remote_i_size; /* Size of the remote file */
66 loff_t zero_point; /* Size after which we assume there's no data
67 * on the server */
68 atomic_t io_count; /* Number of outstanding reqs */
69 unsigned long flags;
70 #define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */
71 #define NETFS_ICTX_UNBUFFERED 1 /* I/O should not use the pagecache */
72 #define NETFS_ICTX_WRITETHROUGH 2 /* Write-through caching */
73 #define NETFS_ICTX_MODIFIED_ATTR 3 /* Indicate change in mtime/ctime */
74 };
75
76 /*
77 * A netfs group - for instance a ceph snap. This is marked on dirty pages and
78 * pages marked with a group must be flushed before they can be written under
79 * the domain of another group.
80 */
81 struct netfs_group {
82 refcount_t ref;
83 void (*free)(struct netfs_group *netfs_group);
84 };
85
86 /*
87 * Information about a dirty page (attached only if necessary).
88 * folio->private
89 */
90 struct netfs_folio {
91 struct netfs_group *netfs_group; /* Filesystem's grouping marker (or NULL). */
92 unsigned int dirty_offset; /* Write-streaming dirty data offset */
93 unsigned int dirty_len; /* Write-streaming dirty data length */
94 };
95 #define NETFS_FOLIO_INFO 0x1UL /* OR'd with folio->private. */
96 #define NETFS_FOLIO_COPY_TO_CACHE ((struct netfs_group *)0x356UL) /* Write to the cache only */
97
netfs_is_folio_info(const void * priv)98 static inline bool netfs_is_folio_info(const void *priv)
99 {
100 return (unsigned long)priv & NETFS_FOLIO_INFO;
101 }
102
__netfs_folio_info(const void * priv)103 static inline struct netfs_folio *__netfs_folio_info(const void *priv)
104 {
105 if (netfs_is_folio_info(priv))
106 return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO);
107 return NULL;
108 }
109
netfs_folio_info(struct folio * folio)110 static inline struct netfs_folio *netfs_folio_info(struct folio *folio)
111 {
112 return __netfs_folio_info(folio_get_private(folio));
113 }
114
netfs_folio_group(struct folio * folio)115 static inline struct netfs_group *netfs_folio_group(struct folio *folio)
116 {
117 struct netfs_folio *finfo;
118 void *priv = folio_get_private(folio);
119
120 finfo = netfs_folio_info(folio);
121 if (finfo)
122 return finfo->netfs_group;
123 return priv;
124 }
125
126 /*
127 * Stream of I/O subrequests going to a particular destination, such as the
128 * server or the local cache. This is mainly intended for writing where we may
129 * have to write to multiple destinations concurrently.
130 */
131 struct netfs_io_stream {
132 /* Submission tracking */
133 struct netfs_io_subrequest *construct; /* Op being constructed */
134 size_t sreq_max_len; /* Maximum size of a subrequest */
135 unsigned int sreq_max_segs; /* 0 or max number of segments in an iterator */
136 unsigned int submit_off; /* Folio offset we're submitting from */
137 unsigned int submit_len; /* Amount of data left to submit */
138 unsigned int submit_extendable_to; /* Amount I/O can be rounded up to */
139 void (*prepare_write)(struct netfs_io_subrequest *subreq);
140 void (*issue_write)(struct netfs_io_subrequest *subreq);
141 /* Collection tracking */
142 struct list_head subrequests; /* Contributory I/O operations */
143 struct netfs_io_subrequest *front; /* Op being collected */
144 unsigned long long collected_to; /* Position we've collected results to */
145 size_t transferred; /* The amount transferred from this stream */
146 enum netfs_io_source source; /* Where to read from/write to */
147 unsigned short error; /* Aggregate error for the stream */
148 unsigned char stream_nr; /* Index of stream in parent table */
149 bool avail; /* T if stream is available */
150 bool active; /* T if stream is active */
151 bool need_retry; /* T if this stream needs retrying */
152 bool failed; /* T if this stream failed */
153 };
154
155 /*
156 * Resources required to do operations on a cache.
157 */
158 struct netfs_cache_resources {
159 const struct netfs_cache_ops *ops;
160 void *cache_priv;
161 void *cache_priv2;
162 unsigned int debug_id; /* Cookie debug ID */
163 unsigned int inval_counter; /* object->inval_counter at begin_op */
164 };
165
166 /*
167 * Descriptor for a single component subrequest. Each operation represents an
168 * individual read/write from/to a server, a cache, a journal, etc..
169 *
170 * The buffer iterator is persistent for the life of the subrequest struct and
171 * the pages it points to can be relied on to exist for the duration.
172 */
173 struct netfs_io_subrequest {
174 struct netfs_io_request *rreq; /* Supervising I/O request */
175 struct work_struct work;
176 struct list_head rreq_link; /* Link in rreq->subrequests */
177 struct iov_iter io_iter; /* Iterator for this subrequest */
178 unsigned long long start; /* Where to start the I/O */
179 size_t len; /* Size of the I/O */
180 size_t transferred; /* Amount of data transferred */
181 size_t consumed; /* Amount of read data consumed */
182 size_t prev_donated; /* Amount of data donated from previous subreq */
183 size_t next_donated; /* Amount of data donated from next subreq */
184 refcount_t ref;
185 short error; /* 0 or error that occurred */
186 unsigned short debug_index; /* Index in list (for debugging output) */
187 unsigned int nr_segs; /* Number of segs in io_iter */
188 u8 retry_count; /* The number of retries (0 on initial pass) */
189 enum netfs_io_source source; /* Where to read from/write to */
190 unsigned char stream_nr; /* I/O stream this belongs to */
191 unsigned char curr_folioq_slot; /* Folio currently being read */
192 unsigned char curr_folio_order; /* Order of folio */
193 struct folio_queue *curr_folioq; /* Queue segment in which current folio resides */
194 unsigned long flags;
195 #define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */
196 #define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */
197 #define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */
198 #define NETFS_SREQ_MADE_PROGRESS 4 /* Set if we transferred at least some data */
199 #define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */
200 #define NETFS_SREQ_BOUNDARY 6 /* Set if ends on hard boundary (eg. ceph object) */
201 #define NETFS_SREQ_HIT_EOF 7 /* Set if short due to EOF */
202 #define NETFS_SREQ_IN_PROGRESS 8 /* Unlocked when the subrequest completes */
203 #define NETFS_SREQ_NEED_RETRY 9 /* Set if the filesystem requests a retry */
204 #define NETFS_SREQ_FAILED 10 /* Set if the subreq failed unretryably */
205 };
206
207 enum netfs_io_origin {
208 NETFS_READAHEAD, /* This read was triggered by readahead */
209 NETFS_READPAGE, /* This read is a synchronous read */
210 NETFS_READ_GAPS, /* This read is a synchronous read to fill gaps */
211 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
212 NETFS_DIO_READ, /* This is a direct I/O read */
213 NETFS_WRITEBACK, /* This write was triggered by writepages */
214 NETFS_WRITETHROUGH, /* This write was made by netfs_perform_write() */
215 NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */
216 NETFS_DIO_WRITE, /* This is a direct I/O write */
217 NETFS_PGPRIV2_COPY_TO_CACHE, /* [DEPRECATED] This is writing read data to the cache */
218 nr__netfs_io_origin
219 } __mode(byte);
220
221 /*
222 * Descriptor for an I/O helper request. This is used to make multiple I/O
223 * operations to a variety of data stores and then stitch the result together.
224 */
225 struct netfs_io_request {
226 union {
227 struct work_struct work;
228 struct rcu_head rcu;
229 };
230 struct inode *inode; /* The file being accessed */
231 struct address_space *mapping; /* The mapping being accessed */
232 struct kiocb *iocb; /* AIO completion vector */
233 struct netfs_cache_resources cache_resources;
234 struct readahead_control *ractl; /* Readahead descriptor */
235 struct list_head proc_link; /* Link in netfs_iorequests */
236 struct list_head subrequests; /* Contributory I/O operations */
237 struct netfs_io_stream io_streams[2]; /* Streams of parallel I/O operations */
238 #define NR_IO_STREAMS 2 //wreq->nr_io_streams
239 struct netfs_group *group; /* Writeback group being written back */
240 struct folio_queue *buffer; /* Head of I/O buffer */
241 struct folio_queue *buffer_tail; /* Tail of I/O buffer */
242 struct iov_iter iter; /* Unencrypted-side iterator */
243 struct iov_iter io_iter; /* I/O (Encrypted-side) iterator */
244 void *netfs_priv; /* Private data for the netfs */
245 void *netfs_priv2; /* Private data for the netfs */
246 struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */
247 unsigned int direct_bv_count; /* Number of elements in direct_bv[] */
248 unsigned int debug_id;
249 unsigned int rsize; /* Maximum read size (0 for none) */
250 unsigned int wsize; /* Maximum write size (0 for none) */
251 atomic_t subreq_counter; /* Next subreq->debug_index */
252 unsigned int nr_group_rel; /* Number of refs to release on ->group */
253 spinlock_t lock; /* Lock for queuing subreqs */
254 atomic_t nr_outstanding; /* Number of ops in progress */
255 unsigned long long submitted; /* Amount submitted for I/O so far */
256 unsigned long long len; /* Length of the request */
257 size_t transferred; /* Amount to be indicated as transferred */
258 long error; /* 0 or error that occurred */
259 enum netfs_io_origin origin; /* Origin of the request */
260 bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */
261 u8 buffer_head_slot; /* First slot in ->buffer */
262 u8 buffer_tail_slot; /* Next slot in ->buffer_tail */
263 unsigned long long i_size; /* Size of the file */
264 unsigned long long start; /* Start position */
265 atomic64_t issued_to; /* Write issuer folio cursor */
266 unsigned long long collected_to; /* Point we've collected to */
267 unsigned long long cleaned_to; /* Position we've cleaned folios to */
268 pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
269 size_t prev_donated; /* Fallback for subreq->prev_donated */
270 refcount_t ref;
271 unsigned long flags;
272 #define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */
273 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */
274 #define NETFS_RREQ_FAILED 4 /* The request failed */
275 #define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */
276 #define NETFS_RREQ_UPLOAD_TO_SERVER 8 /* Need to write to the server */
277 #define NETFS_RREQ_NONBLOCK 9 /* Don't block if possible (O_NONBLOCK) */
278 #define NETFS_RREQ_BLOCKED 10 /* We blocked */
279 #define NETFS_RREQ_PAUSE 11 /* Pause subrequest generation */
280 #define NETFS_RREQ_USE_IO_ITER 12 /* Use ->io_iter rather than ->i_pages */
281 #define NETFS_RREQ_ALL_QUEUED 13 /* All subreqs are now queued */
282 #define NETFS_RREQ_NEED_RETRY 14 /* Need to try retrying */
283 #define NETFS_RREQ_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark
284 * write to cache on read */
285 const struct netfs_request_ops *netfs_ops;
286 void (*cleanup)(struct netfs_io_request *req);
287 };
288
289 /*
290 * Operations the network filesystem can/must provide to the helpers.
291 */
292 struct netfs_request_ops {
293 mempool_t *request_pool;
294 mempool_t *subrequest_pool;
295 int (*init_request)(struct netfs_io_request *rreq, struct file *file);
296 void (*free_request)(struct netfs_io_request *rreq);
297 void (*free_subrequest)(struct netfs_io_subrequest *rreq);
298
299 /* Read request handling */
300 void (*expand_readahead)(struct netfs_io_request *rreq);
301 int (*prepare_read)(struct netfs_io_subrequest *subreq);
302 void (*issue_read)(struct netfs_io_subrequest *subreq);
303 bool (*is_still_valid)(struct netfs_io_request *rreq);
304 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
305 struct folio **foliop, void **_fsdata);
306 void (*done)(struct netfs_io_request *rreq);
307
308 /* Modification handling */
309 void (*update_i_size)(struct inode *inode, loff_t i_size);
310 void (*post_modify)(struct inode *inode);
311
312 /* Write request handling */
313 void (*begin_writeback)(struct netfs_io_request *wreq);
314 void (*prepare_write)(struct netfs_io_subrequest *subreq);
315 void (*issue_write)(struct netfs_io_subrequest *subreq);
316 void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
317 void (*invalidate_cache)(struct netfs_io_request *wreq);
318 };
319
320 /*
321 * How to handle reading from a hole.
322 */
323 enum netfs_read_from_hole {
324 NETFS_READ_HOLE_IGNORE,
325 NETFS_READ_HOLE_CLEAR,
326 NETFS_READ_HOLE_FAIL,
327 };
328
329 /*
330 * Table of operations for access to a cache.
331 */
332 struct netfs_cache_ops {
333 /* End an operation */
334 void (*end_operation)(struct netfs_cache_resources *cres);
335
336 /* Read data from the cache */
337 int (*read)(struct netfs_cache_resources *cres,
338 loff_t start_pos,
339 struct iov_iter *iter,
340 enum netfs_read_from_hole read_hole,
341 netfs_io_terminated_t term_func,
342 void *term_func_priv);
343
344 /* Write data to the cache */
345 int (*write)(struct netfs_cache_resources *cres,
346 loff_t start_pos,
347 struct iov_iter *iter,
348 netfs_io_terminated_t term_func,
349 void *term_func_priv);
350
351 /* Write data to the cache from a netfs subrequest. */
352 void (*issue_write)(struct netfs_io_subrequest *subreq);
353
354 /* Expand readahead request */
355 void (*expand_readahead)(struct netfs_cache_resources *cres,
356 unsigned long long *_start,
357 unsigned long long *_len,
358 unsigned long long i_size);
359
360 /* Prepare a read operation, shortening it to a cached/uncached
361 * boundary as appropriate.
362 */
363 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
364 unsigned long long i_size);
365
366 /* Prepare a write subrequest, working out if we're allowed to do it
367 * and finding out the maximum amount of data to gather before
368 * attempting to submit. If we're not permitted to do it, the
369 * subrequest should be marked failed.
370 */
371 void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq);
372
373 /* Prepare a write operation, working out what part of the write we can
374 * actually do.
375 */
376 int (*prepare_write)(struct netfs_cache_resources *cres,
377 loff_t *_start, size_t *_len, size_t upper_len,
378 loff_t i_size, bool no_space_allocated_yet);
379
380 /* Prepare an on-demand read operation, shortening it to a cached/uncached
381 * boundary as appropriate.
382 */
383 enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
384 loff_t start, size_t *_len,
385 loff_t i_size,
386 unsigned long *_flags, ino_t ino);
387
388 /* Query the occupancy of the cache in a region, returning where the
389 * next chunk of data starts and how long it is.
390 */
391 int (*query_occupancy)(struct netfs_cache_resources *cres,
392 loff_t start, size_t len, size_t granularity,
393 loff_t *_data_start, size_t *_data_len);
394 };
395
396 /* High-level read API. */
397 ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter);
398 ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
399 ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
400 ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
401
402 /* High-level write API */
403 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
404 struct netfs_group *netfs_group);
405 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
406 struct netfs_group *netfs_group);
407 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);
408 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
409 struct netfs_group *netfs_group);
410 ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from);
411
412 /* Address operations API */
413 struct readahead_control;
414 void netfs_readahead(struct readahead_control *);
415 int netfs_read_folio(struct file *, struct folio *);
416 int netfs_write_begin(struct netfs_inode *, struct file *,
417 struct address_space *, loff_t pos, unsigned int len,
418 struct folio **, void **fsdata);
419 int netfs_writepages(struct address_space *mapping,
420 struct writeback_control *wbc);
421 bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio);
422 int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);
423 void netfs_clear_inode_writeback(struct inode *inode, const void *aux);
424 void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
425 bool netfs_release_folio(struct folio *folio, gfp_t gfp);
426
427 /* VMA operations API. */
428 vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
429
430 /* (Sub)request management API. */
431 void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq,
432 bool was_async);
433 void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq,
434 int error, bool was_async);
435 void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
436 enum netfs_sreq_ref_trace what);
437 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
438 bool was_async, enum netfs_sreq_ref_trace what);
439 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
440 struct iov_iter *new,
441 iov_iter_extraction_t extraction_flags);
442 size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
443 size_t max_size, size_t max_segs);
444 void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq);
445 void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
446 bool was_async);
447 void netfs_queue_write_request(struct netfs_io_subrequest *subreq);
448
449 int netfs_start_io_read(struct inode *inode);
450 void netfs_end_io_read(struct inode *inode);
451 int netfs_start_io_write(struct inode *inode);
452 void netfs_end_io_write(struct inode *inode);
453 int netfs_start_io_direct(struct inode *inode);
454 void netfs_end_io_direct(struct inode *inode);
455
456 /**
457 * netfs_inode - Get the netfs inode context from the inode
458 * @inode: The inode to query
459 *
460 * Get the netfs lib inode context from the network filesystem's inode. The
461 * context struct is expected to directly follow on from the VFS inode struct.
462 */
netfs_inode(struct inode * inode)463 static inline struct netfs_inode *netfs_inode(struct inode *inode)
464 {
465 return container_of(inode, struct netfs_inode, inode);
466 }
467
468 /**
469 * netfs_inode_init - Initialise a netfslib inode context
470 * @ctx: The netfs inode to initialise
471 * @ops: The netfs's operations list
472 * @use_zero_point: True to use the zero_point read optimisation
473 *
474 * Initialise the netfs library context struct. This is expected to follow on
475 * directly from the VFS inode struct.
476 */
netfs_inode_init(struct netfs_inode * ctx,const struct netfs_request_ops * ops,bool use_zero_point)477 static inline void netfs_inode_init(struct netfs_inode *ctx,
478 const struct netfs_request_ops *ops,
479 bool use_zero_point)
480 {
481 ctx->ops = ops;
482 ctx->remote_i_size = i_size_read(&ctx->inode);
483 ctx->zero_point = LLONG_MAX;
484 ctx->flags = 0;
485 atomic_set(&ctx->io_count, 0);
486 #if IS_ENABLED(CONFIG_FSCACHE)
487 ctx->cache = NULL;
488 #endif
489 mutex_init(&ctx->wb_lock);
490 /* ->releasepage() drives zero_point */
491 if (use_zero_point) {
492 ctx->zero_point = ctx->remote_i_size;
493 mapping_set_release_always(ctx->inode.i_mapping);
494 }
495 }
496
497 /**
498 * netfs_resize_file - Note that a file got resized
499 * @ctx: The netfs inode being resized
500 * @new_i_size: The new file size
501 * @changed_on_server: The change was applied to the server
502 *
503 * Inform the netfs lib that a file got resized so that it can adjust its state.
504 */
netfs_resize_file(struct netfs_inode * ctx,loff_t new_i_size,bool changed_on_server)505 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size,
506 bool changed_on_server)
507 {
508 if (changed_on_server)
509 ctx->remote_i_size = new_i_size;
510 if (new_i_size < ctx->zero_point)
511 ctx->zero_point = new_i_size;
512 }
513
514 /**
515 * netfs_i_cookie - Get the cache cookie from the inode
516 * @ctx: The netfs inode to query
517 *
518 * Get the caching cookie (if enabled) from the network filesystem's inode.
519 */
netfs_i_cookie(struct netfs_inode * ctx)520 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
521 {
522 #if IS_ENABLED(CONFIG_FSCACHE)
523 return ctx->cache;
524 #else
525 return NULL;
526 #endif
527 }
528
529 /**
530 * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete
531 * @inode: The netfs inode to wait on
532 *
533 * Wait for outstanding I/O requests of any type to complete. This is intended
534 * to be called from inode eviction routines. This makes sure that any
535 * resources held by those requests are cleaned up before we let the inode get
536 * cleaned up.
537 */
netfs_wait_for_outstanding_io(struct inode * inode)538 static inline void netfs_wait_for_outstanding_io(struct inode *inode)
539 {
540 struct netfs_inode *ictx = netfs_inode(inode);
541
542 wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);
543 }
544
545 #endif /* _LINUX_NETFS_H */
546