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 24 /* 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 27 */ 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)) 34 35 /** 36 * folio_start_fscache - Start an fscache write on a folio. 37 * @folio: The folio. 38 * 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. 41 */ 42 static inline void folio_start_fscache(struct folio *folio) 43 { 44 VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio); 45 folio_get(folio); 46 folio_set_private_2(folio); 47 } 48 49 /** 50 * folio_end_fscache - End an fscache write on a folio. 51 * @folio: The folio. 52 * 53 * Call this function after the folio has been written to the local cache. 54 * This will wake any sleepers waiting on this folio. 55 */ 56 static inline void folio_end_fscache(struct folio *folio) 57 { 58 folio_end_private_2(folio); 59 } 60 61 /** 62 * folio_wait_fscache - Wait for an fscache write on this folio to end. 63 * @folio: The folio. 64 * 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. 68 */ 69 static inline void folio_wait_fscache(struct folio *folio) 70 { 71 folio_wait_private_2(folio); 72 } 73 74 /** 75 * folio_wait_fscache_killable - Wait for an fscache write on this folio to end. 76 * @folio: The folio. 77 * 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. 82 * 83 * Return: 84 * - 0 if successful. 85 * - -EINTR if a fatal signal was encountered. 86 */ 87 static inline int folio_wait_fscache_killable(struct folio *folio) 88 { 89 return folio_wait_private_2_killable(folio); 90 } 91 92 static inline void set_page_fscache(struct page *page) 93 { 94 folio_start_fscache(page_folio(page)); 95 } 96 97 static inline void end_page_fscache(struct page *page) 98 { 99 folio_end_private_2(page_folio(page)); 100 } 101 102 static inline void wait_on_page_fscache(struct page *page) 103 { 104 folio_wait_private_2(page_folio(page)); 105 } 106 107 static inline int wait_on_page_fscache_killable(struct page *page) 108 { 109 return folio_wait_private_2_killable(page_folio(page)); 110 } 111 112 enum netfs_io_source { 113 NETFS_FILL_WITH_ZEROES, 114 NETFS_DOWNLOAD_FROM_SERVER, 115 NETFS_READ_FROM_CACHE, 116 NETFS_INVALID_READ, 117 } __mode(byte); 118 119 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error, 120 bool was_async); 121 122 /* 123 * Per-inode context. This wraps the VFS inode. 124 */ 125 struct netfs_inode { 126 struct inode inode; /* The VFS inode */ 127 const struct netfs_request_ops *ops; 128 #if IS_ENABLED(CONFIG_FSCACHE) 129 struct fscache_cookie *cache; 130 #endif 131 loff_t remote_i_size; /* Size of the remote file */ 132 }; 133 134 /* 135 * Resources required to do operations on a cache. 136 */ 137 struct netfs_cache_resources { 138 const struct netfs_cache_ops *ops; 139 void *cache_priv; 140 void *cache_priv2; 141 unsigned int debug_id; /* Cookie debug ID */ 142 unsigned int inval_counter; /* object->inval_counter at begin_op */ 143 }; 144 145 /* 146 * Descriptor for a single component subrequest. 147 */ 148 struct netfs_io_subrequest { 149 struct netfs_io_request *rreq; /* Supervising I/O request */ 150 struct list_head rreq_link; /* Link in rreq->subrequests */ 151 loff_t start; /* Where to start the I/O */ 152 size_t len; /* Size of the I/O */ 153 size_t transferred; /* Amount of data transferred */ 154 refcount_t ref; 155 short error; /* 0 or error that occurred */ 156 unsigned short debug_index; /* Index in list (for debugging output) */ 157 enum netfs_io_source source; /* Where to read from/write to */ 158 unsigned long flags; 159 #define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */ 160 #define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */ 161 #define NETFS_SREQ_SHORT_IO 2 /* Set if the I/O was short */ 162 #define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */ 163 #define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */ 164 #define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */ 165 }; 166 167 enum netfs_io_origin { 168 NETFS_READAHEAD, /* This read was triggered by readahead */ 169 NETFS_READPAGE, /* This read is a synchronous read */ 170 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */ 171 } __mode(byte); 172 173 /* 174 * Descriptor for an I/O helper request. This is used to make multiple I/O 175 * operations to a variety of data stores and then stitch the result together. 176 */ 177 struct netfs_io_request { 178 struct work_struct work; 179 struct inode *inode; /* The file being accessed */ 180 struct address_space *mapping; /* The mapping being accessed */ 181 struct netfs_cache_resources cache_resources; 182 struct list_head subrequests; /* Contributory I/O operations */ 183 void *netfs_priv; /* Private data for the netfs */ 184 unsigned int debug_id; 185 atomic_t nr_outstanding; /* Number of ops in progress */ 186 atomic_t nr_copy_ops; /* Number of copy-to-cache ops in progress */ 187 size_t submitted; /* Amount submitted for I/O so far */ 188 size_t len; /* Length of the request */ 189 short error; /* 0 or error that occurred */ 190 enum netfs_io_origin origin; /* Origin of the request */ 191 loff_t i_size; /* Size of the file */ 192 loff_t start; /* Start position */ 193 pgoff_t no_unlock_folio; /* Don't unlock this folio after read */ 194 refcount_t ref; 195 unsigned long flags; 196 #define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */ 197 #define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */ 198 #define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */ 199 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */ 200 #define NETFS_RREQ_FAILED 4 /* The request failed */ 201 #define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */ 202 const struct netfs_request_ops *netfs_ops; 203 }; 204 205 /* 206 * Operations the network filesystem can/must provide to the helpers. 207 */ 208 struct netfs_request_ops { 209 int (*init_request)(struct netfs_io_request *rreq, struct file *file); 210 void (*free_request)(struct netfs_io_request *rreq); 211 int (*begin_cache_operation)(struct netfs_io_request *rreq); 212 213 void (*expand_readahead)(struct netfs_io_request *rreq); 214 bool (*clamp_length)(struct netfs_io_subrequest *subreq); 215 void (*issue_read)(struct netfs_io_subrequest *subreq); 216 bool (*is_still_valid)(struct netfs_io_request *rreq); 217 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, 218 struct folio **foliop, void **_fsdata); 219 void (*done)(struct netfs_io_request *rreq); 220 }; 221 222 /* 223 * How to handle reading from a hole. 224 */ 225 enum netfs_read_from_hole { 226 NETFS_READ_HOLE_IGNORE, 227 NETFS_READ_HOLE_CLEAR, 228 NETFS_READ_HOLE_FAIL, 229 }; 230 231 /* 232 * Table of operations for access to a cache. This is obtained by 233 * rreq->ops->begin_cache_operation(). 234 */ 235 struct netfs_cache_ops { 236 /* End an operation */ 237 void (*end_operation)(struct netfs_cache_resources *cres); 238 239 /* Read data from the cache */ 240 int (*read)(struct netfs_cache_resources *cres, 241 loff_t start_pos, 242 struct iov_iter *iter, 243 enum netfs_read_from_hole read_hole, 244 netfs_io_terminated_t term_func, 245 void *term_func_priv); 246 247 /* Write data to the cache */ 248 int (*write)(struct netfs_cache_resources *cres, 249 loff_t start_pos, 250 struct iov_iter *iter, 251 netfs_io_terminated_t term_func, 252 void *term_func_priv); 253 254 /* Expand readahead request */ 255 void (*expand_readahead)(struct netfs_cache_resources *cres, 256 loff_t *_start, size_t *_len, loff_t i_size); 257 258 /* Prepare a read operation, shortening it to a cached/uncached 259 * boundary as appropriate. 260 */ 261 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq, 262 loff_t i_size); 263 264 /* Prepare a write operation, working out what part of the write we can 265 * actually do. 266 */ 267 int (*prepare_write)(struct netfs_cache_resources *cres, 268 loff_t *_start, size_t *_len, loff_t i_size, 269 bool no_space_allocated_yet); 270 271 /* Prepare an on-demand read operation, shortening it to a cached/uncached 272 * boundary as appropriate. 273 */ 274 enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres, 275 loff_t start, size_t *_len, 276 loff_t i_size, 277 unsigned long *_flags, ino_t ino); 278 279 /* Query the occupancy of the cache in a region, returning where the 280 * next chunk of data starts and how long it is. 281 */ 282 int (*query_occupancy)(struct netfs_cache_resources *cres, 283 loff_t start, size_t len, size_t granularity, 284 loff_t *_data_start, size_t *_data_len); 285 }; 286 287 struct readahead_control; 288 void netfs_readahead(struct readahead_control *); 289 int netfs_read_folio(struct file *, struct folio *); 290 int netfs_write_begin(struct netfs_inode *, struct file *, 291 struct address_space *, loff_t pos, unsigned int len, 292 struct folio **, void **fsdata); 293 294 void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool); 295 void netfs_get_subrequest(struct netfs_io_subrequest *subreq, 296 enum netfs_sreq_ref_trace what); 297 void netfs_put_subrequest(struct netfs_io_subrequest *subreq, 298 bool was_async, enum netfs_sreq_ref_trace what); 299 void netfs_stats_show(struct seq_file *); 300 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len, 301 struct iov_iter *new, 302 iov_iter_extraction_t extraction_flags); 303 struct sg_table; 304 ssize_t netfs_extract_iter_to_sg(struct iov_iter *iter, size_t len, 305 struct sg_table *sgtable, unsigned int sg_max, 306 iov_iter_extraction_t extraction_flags); 307 308 /** 309 * netfs_inode - Get the netfs inode context from the inode 310 * @inode: The inode to query 311 * 312 * Get the netfs lib inode context from the network filesystem's inode. The 313 * context struct is expected to directly follow on from the VFS inode struct. 314 */ 315 static inline struct netfs_inode *netfs_inode(struct inode *inode) 316 { 317 return container_of(inode, struct netfs_inode, inode); 318 } 319 320 /** 321 * netfs_inode_init - Initialise a netfslib inode context 322 * @ctx: The netfs inode to initialise 323 * @ops: The netfs's operations list 324 * 325 * Initialise the netfs library context struct. This is expected to follow on 326 * directly from the VFS inode struct. 327 */ 328 static inline void netfs_inode_init(struct netfs_inode *ctx, 329 const struct netfs_request_ops *ops) 330 { 331 ctx->ops = ops; 332 ctx->remote_i_size = i_size_read(&ctx->inode); 333 #if IS_ENABLED(CONFIG_FSCACHE) 334 ctx->cache = NULL; 335 #endif 336 } 337 338 /** 339 * netfs_resize_file - Note that a file got resized 340 * @ctx: The netfs inode being resized 341 * @new_i_size: The new file size 342 * 343 * Inform the netfs lib that a file got resized so that it can adjust its state. 344 */ 345 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size) 346 { 347 ctx->remote_i_size = new_i_size; 348 } 349 350 /** 351 * netfs_i_cookie - Get the cache cookie from the inode 352 * @ctx: The netfs inode to query 353 * 354 * Get the caching cookie (if enabled) from the network filesystem's inode. 355 */ 356 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx) 357 { 358 #if IS_ENABLED(CONFIG_FSCACHE) 359 return ctx->cache; 360 #else 361 return NULL; 362 #endif 363 } 364 365 #endif /* _LINUX_NETFS_H */ 366