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#include <linux/rolling_buffer.h>
22
23enum netfs_sreq_ref_trace;
24typedef struct mempool_s mempool_t;
25struct folio_queue;
26
27/**
28 * folio_start_private_2 - Start an fscache write on a folio. [DEPRECATED]
29 * @folio: The folio.
30 *
31 * Call this function before writing a folio to a local cache. Starting a
32 * second write before the first one finishes is not allowed.
33 *
34 * Note that this should no longer be used.
35 */
36static inline void folio_start_private_2(struct folio *folio)
37{
38 VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
39 folio_get(folio);
40 folio_set_private_2(folio);
41}
42
43enum netfs_io_source {
44 NETFS_SOURCE_UNKNOWN,
45 NETFS_FILL_WITH_ZEROES,
46 NETFS_DOWNLOAD_FROM_SERVER,
47 NETFS_READ_FROM_CACHE,
48 NETFS_INVALID_READ,
49 NETFS_UPLOAD_TO_SERVER,
50 NETFS_WRITE_TO_CACHE,
51} __mode(byte);
52
53typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error);
54
55/*
56 * Per-inode context. This wraps the VFS inode.
57 */
58struct 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_MODIFIED_ATTR 3 /* Indicate change in mtime/ctime */
73#define NETFS_ICTX_SINGLE_NO_UPLOAD 4 /* Monolithic payload, cache but no upload */
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 */
81struct 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 */
90struct 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
98static inline bool netfs_is_folio_info(const void *priv)
99{
100 return (unsigned long)priv & NETFS_FOLIO_INFO;
101}
102
103static 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
110static inline struct netfs_folio *netfs_folio_info(struct folio *folio)
111{
112 return __netfs_folio_info(priv: folio_get_private(folio));
113}
114
115static 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 */
131struct 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 unsigned short error; /* Aggregate error for the stream */
147 enum netfs_io_source source; /* Where to read from/write to */
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 */
158struct 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 */
173struct 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 refcount_t ref;
182 short error; /* 0 or error that occurred */
183 unsigned short debug_index; /* Index in list (for debugging output) */
184 unsigned int nr_segs; /* Number of segs in io_iter */
185 u8 retry_count; /* The number of retries (0 on initial pass) */
186 enum netfs_io_source source; /* Where to read from/write to */
187 unsigned char stream_nr; /* I/O stream this belongs to */
188 unsigned long flags;
189#define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */
190#define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */
191#define NETFS_SREQ_MADE_PROGRESS 4 /* Set if we transferred at least some data */
192#define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */
193#define NETFS_SREQ_BOUNDARY 6 /* Set if ends on hard boundary (eg. ceph object) */
194#define NETFS_SREQ_HIT_EOF 7 /* Set if short due to EOF */
195#define NETFS_SREQ_IN_PROGRESS 8 /* Unlocked when the subrequest completes */
196#define NETFS_SREQ_NEED_RETRY 9 /* Set if the filesystem requests a retry */
197#define NETFS_SREQ_FAILED 10 /* Set if the subreq failed unretryably */
198};
199
200enum netfs_io_origin {
201 NETFS_READAHEAD, /* This read was triggered by readahead */
202 NETFS_READPAGE, /* This read is a synchronous read */
203 NETFS_READ_GAPS, /* This read is a synchronous read to fill gaps */
204 NETFS_READ_SINGLE, /* This read should be treated as a single object */
205 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
206 NETFS_UNBUFFERED_READ, /* This is an unbuffered read */
207 NETFS_DIO_READ, /* This is a direct I/O read */
208 NETFS_WRITEBACK, /* This write was triggered by writepages */
209 NETFS_WRITEBACK_SINGLE, /* This monolithic write was triggered by writepages */
210 NETFS_WRITETHROUGH, /* This write was made by netfs_perform_write() */
211 NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */
212 NETFS_DIO_WRITE, /* This is a direct I/O write */
213 NETFS_PGPRIV2_COPY_TO_CACHE, /* [DEPRECATED] This is writing read data to the cache */
214 nr__netfs_io_origin
215} __mode(byte);
216
217/*
218 * Descriptor for an I/O helper request. This is used to make multiple I/O
219 * operations to a variety of data stores and then stitch the result together.
220 */
221struct netfs_io_request {
222 union {
223 struct work_struct cleanup_work; /* Deferred cleanup work */
224 struct rcu_head rcu;
225 };
226 struct work_struct work; /* Result collector work */
227 struct inode *inode; /* The file being accessed */
228 struct address_space *mapping; /* The mapping being accessed */
229 struct kiocb *iocb; /* AIO completion vector */
230 struct netfs_cache_resources cache_resources;
231 struct netfs_io_request *copy_to_cache; /* Request to write just-read data to the cache */
232#ifdef CONFIG_PROC_FS
233 struct list_head proc_link; /* Link in netfs_iorequests */
234#endif
235 struct netfs_io_stream io_streams[2]; /* Streams of parallel I/O operations */
236#define NR_IO_STREAMS 2 //wreq->nr_io_streams
237 struct netfs_group *group; /* Writeback group being written back */
238 struct rolling_buffer buffer; /* Unencrypted buffer */
239#define NETFS_ROLLBUF_PUT_MARK ROLLBUF_MARK_1
240#define NETFS_ROLLBUF_PAGECACHE_MARK ROLLBUF_MARK_2
241 wait_queue_head_t waitq; /* Processor waiter */
242 void *netfs_priv; /* Private data for the netfs */
243 void *netfs_priv2; /* Private data for the netfs */
244 struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */
245 unsigned long long submitted; /* Amount submitted for I/O so far */
246 unsigned long long len; /* Length of the request */
247 size_t transferred; /* Amount to be indicated as transferred */
248 long error; /* 0 or error that occurred */
249 unsigned long long i_size; /* Size of the file */
250 unsigned long long start; /* Start position */
251 atomic64_t issued_to; /* Write issuer folio cursor */
252 unsigned long long collected_to; /* Point we've collected to */
253 unsigned long long cleaned_to; /* Position we've cleaned folios to */
254 unsigned long long abandon_to; /* Position to abandon folios to */
255 pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
256 unsigned int direct_bv_count; /* Number of elements in direct_bv[] */
257 unsigned int debug_id;
258 unsigned int rsize; /* Maximum read size (0 for none) */
259 unsigned int wsize; /* Maximum write size (0 for none) */
260 atomic_t subreq_counter; /* Next subreq->debug_index */
261 unsigned int nr_group_rel; /* Number of refs to release on ->group */
262 spinlock_t lock; /* Lock for queuing subreqs */
263 unsigned char front_folio_order; /* Order (size) of front folio */
264 enum netfs_io_origin origin; /* Origin of the request */
265 bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */
266 refcount_t ref;
267 unsigned long flags;
268#define NETFS_RREQ_OFFLOAD_COLLECTION 0 /* Offload collection to workqueue */
269#define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */
270#define NETFS_RREQ_FAILED 4 /* The request failed */
271#define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes (has ref) */
272#define NETFS_RREQ_FOLIO_COPY_TO_CACHE 6 /* Copy current folio to cache from read */
273#define NETFS_RREQ_UPLOAD_TO_SERVER 8 /* Need to write to the server */
274#define NETFS_RREQ_PAUSE 11 /* Pause subrequest generation */
275#define NETFS_RREQ_USE_IO_ITER 12 /* Use ->io_iter rather than ->i_pages */
276#define NETFS_RREQ_ALL_QUEUED 13 /* All subreqs are now queued */
277#define NETFS_RREQ_RETRYING 14 /* Set if we're in the retry path */
278#define NETFS_RREQ_SHORT_TRANSFER 15 /* Set if we have a short transfer */
279#define NETFS_RREQ_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark
280 * write to cache on read */
281 const struct netfs_request_ops *netfs_ops;
282 void (*cleanup)(struct netfs_io_request *req);
283};
284
285/*
286 * Operations the network filesystem can/must provide to the helpers.
287 */
288struct netfs_request_ops {
289 mempool_t *request_pool;
290 mempool_t *subrequest_pool;
291 int (*init_request)(struct netfs_io_request *rreq, struct file *file);
292 void (*free_request)(struct netfs_io_request *rreq);
293 void (*free_subrequest)(struct netfs_io_subrequest *rreq);
294
295 /* Read request handling */
296 void (*expand_readahead)(struct netfs_io_request *rreq);
297 int (*prepare_read)(struct netfs_io_subrequest *subreq);
298 void (*issue_read)(struct netfs_io_subrequest *subreq);
299 bool (*is_still_valid)(struct netfs_io_request *rreq);
300 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
301 struct folio **foliop, void **_fsdata);
302 void (*done)(struct netfs_io_request *rreq);
303
304 /* Modification handling */
305 void (*update_i_size)(struct inode *inode, loff_t i_size);
306 void (*post_modify)(struct inode *inode);
307
308 /* Write request handling */
309 void (*begin_writeback)(struct netfs_io_request *wreq);
310 void (*prepare_write)(struct netfs_io_subrequest *subreq);
311 void (*issue_write)(struct netfs_io_subrequest *subreq);
312 void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
313 void (*invalidate_cache)(struct netfs_io_request *wreq);
314};
315
316/*
317 * How to handle reading from a hole.
318 */
319enum netfs_read_from_hole {
320 NETFS_READ_HOLE_IGNORE,
321 NETFS_READ_HOLE_FAIL,
322};
323
324/*
325 * Table of operations for access to a cache.
326 */
327struct netfs_cache_ops {
328 /* End an operation */
329 void (*end_operation)(struct netfs_cache_resources *cres);
330
331 /* Read data from the cache */
332 int (*read)(struct netfs_cache_resources *cres,
333 loff_t start_pos,
334 struct iov_iter *iter,
335 enum netfs_read_from_hole read_hole,
336 netfs_io_terminated_t term_func,
337 void *term_func_priv);
338
339 /* Write data to the cache */
340 int (*write)(struct netfs_cache_resources *cres,
341 loff_t start_pos,
342 struct iov_iter *iter,
343 netfs_io_terminated_t term_func,
344 void *term_func_priv);
345
346 /* Write data to the cache from a netfs subrequest. */
347 void (*issue_write)(struct netfs_io_subrequest *subreq);
348
349 /* Expand readahead request */
350 void (*expand_readahead)(struct netfs_cache_resources *cres,
351 unsigned long long *_start,
352 unsigned long long *_len,
353 unsigned long long i_size);
354
355 /* Prepare a read operation, shortening it to a cached/uncached
356 * boundary as appropriate.
357 */
358 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
359 unsigned long long i_size);
360
361 /* Prepare a write subrequest, working out if we're allowed to do it
362 * and finding out the maximum amount of data to gather before
363 * attempting to submit. If we're not permitted to do it, the
364 * subrequest should be marked failed.
365 */
366 void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq);
367
368 /* Prepare a write operation, working out what part of the write we can
369 * actually do.
370 */
371 int (*prepare_write)(struct netfs_cache_resources *cres,
372 loff_t *_start, size_t *_len, size_t upper_len,
373 loff_t i_size, bool no_space_allocated_yet);
374
375 /* Prepare an on-demand read operation, shortening it to a cached/uncached
376 * boundary as appropriate.
377 */
378 enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
379 loff_t start, size_t *_len,
380 loff_t i_size,
381 unsigned long *_flags, ino_t ino);
382
383 /* Query the occupancy of the cache in a region, returning where the
384 * next chunk of data starts and how long it is.
385 */
386 int (*query_occupancy)(struct netfs_cache_resources *cres,
387 loff_t start, size_t len, size_t granularity,
388 loff_t *_data_start, size_t *_data_len);
389};
390
391/* High-level read API. */
392ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter);
393ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
394ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
395ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
396
397/* High-level write API */
398ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
399 struct netfs_group *netfs_group);
400ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
401 struct netfs_group *netfs_group);
402ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);
403ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
404 struct netfs_group *netfs_group);
405ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from);
406
407/* Single, monolithic object read/write API. */
408void netfs_single_mark_inode_dirty(struct inode *inode);
409ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter);
410int netfs_writeback_single(struct address_space *mapping,
411 struct writeback_control *wbc,
412 struct iov_iter *iter);
413
414/* Address operations API */
415struct readahead_control;
416void netfs_readahead(struct readahead_control *);
417int netfs_read_folio(struct file *, struct folio *);
418int netfs_write_begin(struct netfs_inode *, struct file *,
419 struct address_space *, loff_t pos, unsigned int len,
420 struct folio **, void **fsdata);
421int netfs_writepages(struct address_space *mapping,
422 struct writeback_control *wbc);
423bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio);
424int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);
425void netfs_clear_inode_writeback(struct inode *inode, const void *aux);
426void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
427bool netfs_release_folio(struct folio *folio, gfp_t gfp);
428
429/* VMA operations API. */
430vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
431
432/* (Sub)request management API. */
433void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq);
434void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq);
435void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
436 enum netfs_sreq_ref_trace what);
437void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
438 enum netfs_sreq_ref_trace what);
439ssize_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);
442size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
443 size_t max_size, size_t max_segs);
444void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq);
445void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error);
446void netfs_queue_write_request(struct netfs_io_subrequest *subreq);
447
448int netfs_start_io_read(struct inode *inode);
449void netfs_end_io_read(struct inode *inode);
450int netfs_start_io_write(struct inode *inode);
451void netfs_end_io_write(struct inode *inode);
452int netfs_start_io_direct(struct inode *inode);
453void netfs_end_io_direct(struct inode *inode);
454
455/* Miscellaneous APIs. */
456struct folio_queue *netfs_folioq_alloc(unsigned int rreq_id, gfp_t gfp,
457 unsigned int trace /*enum netfs_folioq_trace*/);
458void netfs_folioq_free(struct folio_queue *folioq,
459 unsigned int trace /*enum netfs_trace_folioq*/);
460
461/* Buffer wrangling helpers API. */
462int netfs_alloc_folioq_buffer(struct address_space *mapping,
463 struct folio_queue **_buffer,
464 size_t *_cur_size, ssize_t size, gfp_t gfp);
465void netfs_free_folioq_buffer(struct folio_queue *fq);
466
467/**
468 * netfs_inode - Get the netfs inode context from the inode
469 * @inode: The inode to query
470 *
471 * Get the netfs lib inode context from the network filesystem's inode. The
472 * context struct is expected to directly follow on from the VFS inode struct.
473 */
474static inline struct netfs_inode *netfs_inode(struct inode *inode)
475{
476 return container_of(inode, struct netfs_inode, inode);
477}
478
479/**
480 * netfs_inode_init - Initialise a netfslib inode context
481 * @ctx: The netfs inode to initialise
482 * @ops: The netfs's operations list
483 * @use_zero_point: True to use the zero_point read optimisation
484 *
485 * Initialise the netfs library context struct. This is expected to follow on
486 * directly from the VFS inode struct.
487 */
488static inline void netfs_inode_init(struct netfs_inode *ctx,
489 const struct netfs_request_ops *ops,
490 bool use_zero_point)
491{
492 ctx->ops = ops;
493 ctx->remote_i_size = i_size_read(inode: &ctx->inode);
494 ctx->zero_point = LLONG_MAX;
495 ctx->flags = 0;
496 atomic_set(v: &ctx->io_count, i: 0);
497#if IS_ENABLED(CONFIG_FSCACHE)
498 ctx->cache = NULL;
499#endif
500 mutex_init(&ctx->wb_lock);
501 /* ->releasepage() drives zero_point */
502 if (use_zero_point) {
503 ctx->zero_point = ctx->remote_i_size;
504 mapping_set_release_always(mapping: ctx->inode.i_mapping);
505 }
506}
507
508/**
509 * netfs_resize_file - Note that a file got resized
510 * @ctx: The netfs inode being resized
511 * @new_i_size: The new file size
512 * @changed_on_server: The change was applied to the server
513 *
514 * Inform the netfs lib that a file got resized so that it can adjust its state.
515 */
516static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size,
517 bool changed_on_server)
518{
519 if (changed_on_server)
520 ctx->remote_i_size = new_i_size;
521 if (new_i_size < ctx->zero_point)
522 ctx->zero_point = new_i_size;
523}
524
525/**
526 * netfs_i_cookie - Get the cache cookie from the inode
527 * @ctx: The netfs inode to query
528 *
529 * Get the caching cookie (if enabled) from the network filesystem's inode.
530 */
531static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
532{
533#if IS_ENABLED(CONFIG_FSCACHE)
534 return ctx->cache;
535#else
536 return NULL;
537#endif
538}
539
540/**
541 * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete
542 * @inode: The netfs inode to wait on
543 *
544 * Wait for outstanding I/O requests of any type to complete. This is intended
545 * to be called from inode eviction routines. This makes sure that any
546 * resources held by those requests are cleaned up before we let the inode get
547 * cleaned up.
548 */
549static inline void netfs_wait_for_outstanding_io(struct inode *inode)
550{
551 struct netfs_inode *ictx = netfs_inode(inode);
552
553 wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);
554}
555
556#endif /* _LINUX_NETFS_H */
557

source code of linux/include/linux/netfs.h

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