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>
20 #include <linux/uio.h>
22 enum netfs_sreq_ref_trace;
25 * Overload PG_private_2 to give us PG_fscache - this is used to indicate that
26 * a page is currently backed by a local disk cache
28 #define folio_test_fscache(folio) folio_test_private_2(folio)
29 #define PageFsCache(page) PagePrivate2((page))
30 #define SetPageFsCache(page) SetPagePrivate2((page))
31 #define ClearPageFsCache(page) ClearPagePrivate2((page))
32 #define TestSetPageFsCache(page) TestSetPagePrivate2((page))
33 #define TestClearPageFsCache(page) TestClearPagePrivate2((page))
36 * folio_start_fscache - Start an fscache write on a folio.
39 * Call this function before writing a folio to a local cache. Starting a
40 * second write before the first one finishes is not allowed.
42 static inline void folio_start_fscache(struct folio *folio)
44 VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
46 folio_set_private_2(folio);
50 * folio_end_fscache - End an fscache write on a folio.
53 * Call this function after the folio has been written to the local cache.
54 * This will wake any sleepers waiting on this folio.
56 static inline void folio_end_fscache(struct folio *folio)
58 folio_end_private_2(folio);
62 * folio_wait_fscache - Wait for an fscache write on this folio to end.
65 * If this folio is currently being written to a local cache, wait for
66 * the write to finish. Another write may start after this one finishes,
67 * unless the caller holds the folio lock.
69 static inline void folio_wait_fscache(struct folio *folio)
71 folio_wait_private_2(folio);
75 * folio_wait_fscache_killable - Wait for an fscache write on this folio to end.
78 * If this folio is currently being written to a local cache, wait
79 * for the write to finish or for a fatal signal to be received.
80 * Another write may start after this one finishes, unless the caller
81 * holds the folio lock.
85 * - -EINTR if a fatal signal was encountered.
87 static inline int folio_wait_fscache_killable(struct folio *folio)
89 return folio_wait_private_2_killable(folio);
92 static inline void set_page_fscache(struct page *page)
94 folio_start_fscache(page_folio(page));
97 static inline void end_page_fscache(struct page *page)
99 folio_end_private_2(page_folio(page));
102 static inline void wait_on_page_fscache(struct page *page)
104 folio_wait_private_2(page_folio(page));
107 static inline int wait_on_page_fscache_killable(struct page *page)
109 return folio_wait_private_2_killable(page_folio(page));
112 /* Marks used on xarray-based buffers */
113 #define NETFS_BUF_PUT_MARK XA_MARK_0 /* - Page needs putting */
114 #define NETFS_BUF_PAGECACHE_MARK XA_MARK_1 /* - Page needs wb/dirty flag wrangling */
116 enum netfs_io_source {
117 NETFS_FILL_WITH_ZEROES,
118 NETFS_DOWNLOAD_FROM_SERVER,
119 NETFS_READ_FROM_CACHE,
123 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
127 * Per-inode context. This wraps the VFS inode.
130 struct inode inode; /* The VFS inode */
131 const struct netfs_request_ops *ops;
132 #if IS_ENABLED(CONFIG_FSCACHE)
133 struct fscache_cookie *cache;
135 loff_t remote_i_size; /* Size of the remote file */
137 #define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */
141 * Resources required to do operations on a cache.
143 struct netfs_cache_resources {
144 const struct netfs_cache_ops *ops;
147 unsigned int debug_id; /* Cookie debug ID */
148 unsigned int inval_counter; /* object->inval_counter at begin_op */
152 * Descriptor for a single component subrequest.
154 struct netfs_io_subrequest {
155 struct netfs_io_request *rreq; /* Supervising I/O request */
156 struct list_head rreq_link; /* Link in rreq->subrequests */
157 struct iov_iter io_iter; /* Iterator for this subrequest */
158 loff_t start; /* Where to start the I/O */
159 size_t len; /* Size of the I/O */
160 size_t transferred; /* Amount of data transferred */
162 short error; /* 0 or error that occurred */
163 unsigned short debug_index; /* Index in list (for debugging output) */
164 unsigned int max_nr_segs; /* 0 or max number of segments in an iterator */
165 enum netfs_io_source source; /* Where to read from/write to */
167 #define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */
168 #define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */
169 #define NETFS_SREQ_SHORT_IO 2 /* Set if the I/O was short */
170 #define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */
171 #define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */
172 #define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */
175 enum netfs_io_origin {
176 NETFS_READAHEAD, /* This read was triggered by readahead */
177 NETFS_READPAGE, /* This read is a synchronous read */
178 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
182 * Descriptor for an I/O helper request. This is used to make multiple I/O
183 * operations to a variety of data stores and then stitch the result together.
185 struct netfs_io_request {
187 struct work_struct work;
190 struct inode *inode; /* The file being accessed */
191 struct address_space *mapping; /* The mapping being accessed */
192 struct netfs_cache_resources cache_resources;
193 struct list_head proc_link; /* Link in netfs_iorequests */
194 struct list_head subrequests; /* Contributory I/O operations */
195 struct iov_iter iter; /* Unencrypted-side iterator */
196 struct iov_iter io_iter; /* I/O (Encrypted-side) iterator */
197 void *netfs_priv; /* Private data for the netfs */
198 struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */
199 unsigned int direct_bv_count; /* Number of elements in direct_bv[] */
200 unsigned int debug_id;
201 atomic_t nr_outstanding; /* Number of ops in progress */
202 atomic_t nr_copy_ops; /* Number of copy-to-cache ops in progress */
203 size_t submitted; /* Amount submitted for I/O so far */
204 size_t len; /* Length of the request */
205 short error; /* 0 or error that occurred */
206 enum netfs_io_origin origin; /* Origin of the request */
207 bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */
208 loff_t i_size; /* Size of the file */
209 loff_t start; /* Start position */
210 pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
213 #define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */
214 #define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */
215 #define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */
216 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */
217 #define NETFS_RREQ_FAILED 4 /* The request failed */
218 #define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */
219 const struct netfs_request_ops *netfs_ops;
223 * Operations the network filesystem can/must provide to the helpers.
225 struct netfs_request_ops {
226 unsigned int io_request_size; /* Alloc size for netfs_io_request struct */
227 unsigned int io_subrequest_size; /* Alloc size for netfs_io_subrequest struct */
228 int (*init_request)(struct netfs_io_request *rreq, struct file *file);
229 void (*free_request)(struct netfs_io_request *rreq);
230 void (*free_subrequest)(struct netfs_io_subrequest *rreq);
232 void (*expand_readahead)(struct netfs_io_request *rreq);
233 bool (*clamp_length)(struct netfs_io_subrequest *subreq);
234 void (*issue_read)(struct netfs_io_subrequest *subreq);
235 bool (*is_still_valid)(struct netfs_io_request *rreq);
236 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
237 struct folio **foliop, void **_fsdata);
238 void (*done)(struct netfs_io_request *rreq);
242 * How to handle reading from a hole.
244 enum netfs_read_from_hole {
245 NETFS_READ_HOLE_IGNORE,
246 NETFS_READ_HOLE_CLEAR,
247 NETFS_READ_HOLE_FAIL,
251 * Table of operations for access to a cache.
253 struct netfs_cache_ops {
254 /* End an operation */
255 void (*end_operation)(struct netfs_cache_resources *cres);
257 /* Read data from the cache */
258 int (*read)(struct netfs_cache_resources *cres,
260 struct iov_iter *iter,
261 enum netfs_read_from_hole read_hole,
262 netfs_io_terminated_t term_func,
263 void *term_func_priv);
265 /* Write data to the cache */
266 int (*write)(struct netfs_cache_resources *cres,
268 struct iov_iter *iter,
269 netfs_io_terminated_t term_func,
270 void *term_func_priv);
272 /* Expand readahead request */
273 void (*expand_readahead)(struct netfs_cache_resources *cres,
274 loff_t *_start, size_t *_len, loff_t i_size);
276 /* Prepare a read operation, shortening it to a cached/uncached
277 * boundary as appropriate.
279 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
282 /* Prepare a write operation, working out what part of the write we can
285 int (*prepare_write)(struct netfs_cache_resources *cres,
286 loff_t *_start, size_t *_len, loff_t i_size,
287 bool no_space_allocated_yet);
289 /* Prepare an on-demand read operation, shortening it to a cached/uncached
290 * boundary as appropriate.
292 enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
293 loff_t start, size_t *_len,
295 unsigned long *_flags, ino_t ino);
297 /* Query the occupancy of the cache in a region, returning where the
298 * next chunk of data starts and how long it is.
300 int (*query_occupancy)(struct netfs_cache_resources *cres,
301 loff_t start, size_t len, size_t granularity,
302 loff_t *_data_start, size_t *_data_len);
305 struct readahead_control;
306 void netfs_readahead(struct readahead_control *);
307 int netfs_read_folio(struct file *, struct folio *);
308 int netfs_write_begin(struct netfs_inode *, struct file *,
309 struct address_space *, loff_t pos, unsigned int len,
310 struct folio **, void **fsdata);
311 bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio);
312 int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);
313 void netfs_clear_inode_writeback(struct inode *inode, const void *aux);
314 void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
315 bool netfs_release_folio(struct folio *folio, gfp_t gfp);
317 void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool);
318 void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
319 enum netfs_sreq_ref_trace what);
320 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
321 bool was_async, enum netfs_sreq_ref_trace what);
322 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
323 struct iov_iter *new,
324 iov_iter_extraction_t extraction_flags);
325 size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
326 size_t max_size, size_t max_segs);
328 int netfs_start_io_read(struct inode *inode);
329 void netfs_end_io_read(struct inode *inode);
330 int netfs_start_io_write(struct inode *inode);
331 void netfs_end_io_write(struct inode *inode);
332 int netfs_start_io_direct(struct inode *inode);
333 void netfs_end_io_direct(struct inode *inode);
336 * netfs_inode - Get the netfs inode context from the inode
337 * @inode: The inode to query
339 * Get the netfs lib inode context from the network filesystem's inode. The
340 * context struct is expected to directly follow on from the VFS inode struct.
342 static inline struct netfs_inode *netfs_inode(struct inode *inode)
344 return container_of(inode, struct netfs_inode, inode);
348 * netfs_inode_init - Initialise a netfslib inode context
349 * @ctx: The netfs inode to initialise
350 * @ops: The netfs's operations list
352 * Initialise the netfs library context struct. This is expected to follow on
353 * directly from the VFS inode struct.
355 static inline void netfs_inode_init(struct netfs_inode *ctx,
356 const struct netfs_request_ops *ops)
359 ctx->remote_i_size = i_size_read(&ctx->inode);
361 #if IS_ENABLED(CONFIG_FSCACHE)
367 * netfs_resize_file - Note that a file got resized
368 * @ctx: The netfs inode being resized
369 * @new_i_size: The new file size
371 * Inform the netfs lib that a file got resized so that it can adjust its state.
373 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size)
375 ctx->remote_i_size = new_i_size;
379 * netfs_i_cookie - Get the cache cookie from the inode
380 * @ctx: The netfs inode to query
382 * Get the caching cookie (if enabled) from the network filesystem's inode.
384 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
386 #if IS_ENABLED(CONFIG_FSCACHE)
393 #endif /* _LINUX_NETFS_H */