1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /* Network filesystem support services.
4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
9 * Documentation/filesystems/netfs_library.rst
11 * for a description of the network filesystem interface declared here.
14 #ifndef _LINUX_NETFS_H
15 #define _LINUX_NETFS_H
17 #include <linux/workqueue.h>
19 #include <linux/pagemap.h>
21 enum netfs_sreq_ref_trace;
24 * Overload PG_private_2 to give us PG_fscache - this is used to indicate that
25 * a page is currently backed by a local disk cache
27 #define folio_test_fscache(folio) folio_test_private_2(folio)
28 #define PageFsCache(page) PagePrivate2((page))
29 #define SetPageFsCache(page) SetPagePrivate2((page))
30 #define ClearPageFsCache(page) ClearPagePrivate2((page))
31 #define TestSetPageFsCache(page) TestSetPagePrivate2((page))
32 #define TestClearPageFsCache(page) TestClearPagePrivate2((page))
35 * folio_start_fscache - Start an fscache write on a folio.
38 * Call this function before writing a folio to a local cache. Starting a
39 * second write before the first one finishes is not allowed.
41 static inline void folio_start_fscache(struct folio *folio)
43 VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
45 folio_set_private_2(folio);
49 * folio_end_fscache - End an fscache write on a folio.
52 * Call this function after the folio has been written to the local cache.
53 * This will wake any sleepers waiting on this folio.
55 static inline void folio_end_fscache(struct folio *folio)
57 folio_end_private_2(folio);
61 * folio_wait_fscache - Wait for an fscache write on this folio to end.
64 * If this folio is currently being written to a local cache, wait for
65 * the write to finish. Another write may start after this one finishes,
66 * unless the caller holds the folio lock.
68 static inline void folio_wait_fscache(struct folio *folio)
70 folio_wait_private_2(folio);
74 * folio_wait_fscache_killable - Wait for an fscache write on this folio to end.
77 * If this folio is currently being written to a local cache, wait
78 * for the write to finish or for a fatal signal to be received.
79 * Another write may start after this one finishes, unless the caller
80 * holds the folio lock.
84 * - -EINTR if a fatal signal was encountered.
86 static inline int folio_wait_fscache_killable(struct folio *folio)
88 return folio_wait_private_2_killable(folio);
91 static inline void set_page_fscache(struct page *page)
93 folio_start_fscache(page_folio(page));
96 static inline void end_page_fscache(struct page *page)
98 folio_end_private_2(page_folio(page));
101 static inline void wait_on_page_fscache(struct page *page)
103 folio_wait_private_2(page_folio(page));
106 static inline int wait_on_page_fscache_killable(struct page *page)
108 return folio_wait_private_2_killable(page_folio(page));
111 enum netfs_io_source {
112 NETFS_FILL_WITH_ZEROES,
113 NETFS_DOWNLOAD_FROM_SERVER,
114 NETFS_READ_FROM_CACHE,
118 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
122 * Per-inode description. This must be directly after the inode struct.
124 struct netfs_i_context {
125 const struct netfs_request_ops *ops;
126 #if IS_ENABLED(CONFIG_FSCACHE)
127 struct fscache_cookie *cache;
129 loff_t remote_i_size; /* Size of the remote file */
133 * Resources required to do operations on a cache.
135 struct netfs_cache_resources {
136 const struct netfs_cache_ops *ops;
139 unsigned int debug_id; /* Cookie debug ID */
140 unsigned int inval_counter; /* object->inval_counter at begin_op */
144 * Descriptor for a single component subrequest.
146 struct netfs_io_subrequest {
147 struct netfs_io_request *rreq; /* Supervising I/O request */
148 struct list_head rreq_link; /* Link in rreq->subrequests */
149 loff_t start; /* Where to start the I/O */
150 size_t len; /* Size of the I/O */
151 size_t transferred; /* Amount of data transferred */
153 short error; /* 0 or error that occurred */
154 unsigned short debug_index; /* Index in list (for debugging output) */
155 enum netfs_io_source source; /* Where to read from/write to */
157 #define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */
158 #define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */
159 #define NETFS_SREQ_SHORT_IO 2 /* Set if the I/O was short */
160 #define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */
161 #define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */
164 enum netfs_io_origin {
165 NETFS_READAHEAD, /* This read was triggered by readahead */
166 NETFS_READPAGE, /* This read is a synchronous read */
167 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
171 * Descriptor for an I/O helper request. This is used to make multiple I/O
172 * operations to a variety of data stores and then stitch the result together.
174 struct netfs_io_request {
175 struct work_struct work;
176 struct inode *inode; /* The file being accessed */
177 struct address_space *mapping; /* The mapping being accessed */
178 struct netfs_cache_resources cache_resources;
179 struct list_head subrequests; /* Contributory I/O operations */
180 void *netfs_priv; /* Private data for the netfs */
181 unsigned int debug_id;
182 atomic_t nr_outstanding; /* Number of ops in progress */
183 atomic_t nr_copy_ops; /* Number of copy-to-cache ops in progress */
184 size_t submitted; /* Amount submitted for I/O so far */
185 size_t len; /* Length of the request */
186 short error; /* 0 or error that occurred */
187 enum netfs_io_origin origin; /* Origin of the request */
188 loff_t i_size; /* Size of the file */
189 loff_t start; /* Start position */
190 pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
193 #define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */
194 #define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */
195 #define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */
196 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */
197 #define NETFS_RREQ_FAILED 4 /* The request failed */
198 #define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */
199 const struct netfs_request_ops *netfs_ops;
203 * Operations the network filesystem can/must provide to the helpers.
205 struct netfs_request_ops {
206 int (*init_request)(struct netfs_io_request *rreq, struct file *file);
207 int (*begin_cache_operation)(struct netfs_io_request *rreq);
208 void (*expand_readahead)(struct netfs_io_request *rreq);
209 bool (*clamp_length)(struct netfs_io_subrequest *subreq);
210 void (*issue_read)(struct netfs_io_subrequest *subreq);
211 bool (*is_still_valid)(struct netfs_io_request *rreq);
212 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
213 struct folio *folio, void **_fsdata);
214 void (*done)(struct netfs_io_request *rreq);
215 void (*cleanup)(struct address_space *mapping, void *netfs_priv);
219 * How to handle reading from a hole.
221 enum netfs_read_from_hole {
222 NETFS_READ_HOLE_IGNORE,
223 NETFS_READ_HOLE_CLEAR,
224 NETFS_READ_HOLE_FAIL,
228 * Table of operations for access to a cache. This is obtained by
229 * rreq->ops->begin_cache_operation().
231 struct netfs_cache_ops {
232 /* End an operation */
233 void (*end_operation)(struct netfs_cache_resources *cres);
235 /* Read data from the cache */
236 int (*read)(struct netfs_cache_resources *cres,
238 struct iov_iter *iter,
239 enum netfs_read_from_hole read_hole,
240 netfs_io_terminated_t term_func,
241 void *term_func_priv);
243 /* Write data to the cache */
244 int (*write)(struct netfs_cache_resources *cres,
246 struct iov_iter *iter,
247 netfs_io_terminated_t term_func,
248 void *term_func_priv);
250 /* Expand readahead request */
251 void (*expand_readahead)(struct netfs_cache_resources *cres,
252 loff_t *_start, size_t *_len, loff_t i_size);
254 /* Prepare a read operation, shortening it to a cached/uncached
255 * boundary as appropriate.
257 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
260 /* Prepare a write operation, working out what part of the write we can
263 int (*prepare_write)(struct netfs_cache_resources *cres,
264 loff_t *_start, size_t *_len, loff_t i_size,
265 bool no_space_allocated_yet);
267 /* Query the occupancy of the cache in a region, returning where the
268 * next chunk of data starts and how long it is.
270 int (*query_occupancy)(struct netfs_cache_resources *cres,
271 loff_t start, size_t len, size_t granularity,
272 loff_t *_data_start, size_t *_data_len);
275 struct readahead_control;
276 extern void netfs_readahead(struct readahead_control *);
277 extern int netfs_readpage(struct file *, struct page *);
278 extern int netfs_write_begin(struct file *, struct address_space *,
279 loff_t, unsigned int, unsigned int, struct folio **,
282 extern void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool);
283 extern void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
284 enum netfs_sreq_ref_trace what);
285 extern void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
286 bool was_async, enum netfs_sreq_ref_trace what);
287 extern void netfs_stats_show(struct seq_file *);
290 * netfs_i_context - Get the netfs inode context from the inode
291 * @inode: The inode to query
293 * Get the netfs lib inode context from the network filesystem's inode. The
294 * context struct is expected to directly follow on from the VFS inode struct.
296 static inline struct netfs_i_context *netfs_i_context(struct inode *inode)
298 return (struct netfs_i_context *)(inode + 1);
302 * netfs_inode - Get the netfs inode from the inode context
303 * @ctx: The context to query
305 * Get the netfs inode from the netfs library's inode context. The VFS inode
306 * is expected to directly precede the context struct.
308 static inline struct inode *netfs_inode(struct netfs_i_context *ctx)
310 return ((struct inode *)ctx) - 1;
314 * netfs_i_context_init - Initialise a netfs lib context
315 * @inode: The inode with which the context is associated
316 * @ops: The netfs's operations list
318 * Initialise the netfs library context struct. This is expected to follow on
319 * directly from the VFS inode struct.
321 static inline void netfs_i_context_init(struct inode *inode,
322 const struct netfs_request_ops *ops)
324 struct netfs_i_context *ctx = netfs_i_context(inode);
326 memset(ctx, 0, sizeof(*ctx));
328 ctx->remote_i_size = i_size_read(inode);
332 * netfs_resize_file - Note that a file got resized
333 * @inode: The inode being resized
334 * @new_i_size: The new file size
336 * Inform the netfs lib that a file got resized so that it can adjust its state.
338 static inline void netfs_resize_file(struct inode *inode, loff_t new_i_size)
340 struct netfs_i_context *ctx = netfs_i_context(inode);
342 ctx->remote_i_size = new_i_size;
346 * netfs_i_cookie - Get the cache cookie from the inode
347 * @inode: The inode to query
349 * Get the caching cookie (if enabled) from the network filesystem's inode.
351 static inline struct fscache_cookie *netfs_i_cookie(struct inode *inode)
353 #if IS_ENABLED(CONFIG_FSCACHE)
354 struct netfs_i_context *ctx = netfs_i_context(inode);
361 #endif /* _LINUX_NETFS_H */