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 21 enum netfs_sreq_ref_trace; 22 23 /* 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 26 */ 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)) 33 34 /** 35 * folio_start_fscache - Start an fscache write on a folio. 36 * @folio: The folio. 37 * 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. 40 */ 41 static inline void folio_start_fscache(struct folio *folio) 42 { 43 VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio); 44 folio_get(folio); 45 folio_set_private_2(folio); 46 } 47 48 /** 49 * folio_end_fscache - End an fscache write on a folio. 50 * @folio: The folio. 51 * 52 * Call this function after the folio has been written to the local cache. 53 * This will wake any sleepers waiting on this folio. 54 */ 55 static inline void folio_end_fscache(struct folio *folio) 56 { 57 folio_end_private_2(folio); 58 } 59 60 /** 61 * folio_wait_fscache - Wait for an fscache write on this folio to end. 62 * @folio: The folio. 63 * 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. 67 */ 68 static inline void folio_wait_fscache(struct folio *folio) 69 { 70 folio_wait_private_2(folio); 71 } 72 73 /** 74 * folio_wait_fscache_killable - Wait for an fscache write on this folio to end. 75 * @folio: The folio. 76 * 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. 81 * 82 * Return: 83 * - 0 if successful. 84 * - -EINTR if a fatal signal was encountered. 85 */ 86 static inline int folio_wait_fscache_killable(struct folio *folio) 87 { 88 return folio_wait_private_2_killable(folio); 89 } 90 91 static inline void set_page_fscache(struct page *page) 92 { 93 folio_start_fscache(page_folio(page)); 94 } 95 96 static inline void end_page_fscache(struct page *page) 97 { 98 folio_end_private_2(page_folio(page)); 99 } 100 101 static inline void wait_on_page_fscache(struct page *page) 102 { 103 folio_wait_private_2(page_folio(page)); 104 } 105 106 static inline int wait_on_page_fscache_killable(struct page *page) 107 { 108 return folio_wait_private_2_killable(page_folio(page)); 109 } 110 111 enum netfs_io_source { 112 NETFS_FILL_WITH_ZEROES, 113 NETFS_DOWNLOAD_FROM_SERVER, 114 NETFS_READ_FROM_CACHE, 115 NETFS_INVALID_READ, 116 } __mode(byte); 117 118 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error, 119 bool was_async); 120 121 /* 122 * Per-inode context. This wraps the VFS inode. 123 */ 124 struct netfs_inode { 125 struct inode inode; /* The VFS inode */ 126 const struct netfs_request_ops *ops; 127 #if IS_ENABLED(CONFIG_FSCACHE) 128 struct fscache_cookie *cache; 129 #endif 130 loff_t remote_i_size; /* Size of the remote file */ 131 }; 132 133 /* 134 * Resources required to do operations on a cache. 135 */ 136 struct netfs_cache_resources { 137 const struct netfs_cache_ops *ops; 138 void *cache_priv; 139 void *cache_priv2; 140 unsigned int debug_id; /* Cookie debug ID */ 141 unsigned int inval_counter; /* object->inval_counter at begin_op */ 142 }; 143 144 /* 145 * Descriptor for a single component subrequest. 146 */ 147 struct netfs_io_subrequest { 148 struct netfs_io_request *rreq; /* Supervising I/O request */ 149 struct list_head rreq_link; /* Link in rreq->subrequests */ 150 loff_t start; /* Where to start the I/O */ 151 size_t len; /* Size of the I/O */ 152 size_t transferred; /* Amount of data transferred */ 153 refcount_t ref; 154 short error; /* 0 or error that occurred */ 155 unsigned short debug_index; /* Index in list (for debugging output) */ 156 enum netfs_io_source source; /* Where to read from/write to */ 157 unsigned long flags; 158 #define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */ 159 #define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */ 160 #define NETFS_SREQ_SHORT_IO 2 /* Set if the I/O was short */ 161 #define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */ 162 #define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */ 163 #define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */ 164 }; 165 166 enum netfs_io_origin { 167 NETFS_READAHEAD, /* This read was triggered by readahead */ 168 NETFS_READPAGE, /* This read is a synchronous read */ 169 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */ 170 } __mode(byte); 171 172 /* 173 * Descriptor for an I/O helper request. This is used to make multiple I/O 174 * operations to a variety of data stores and then stitch the result together. 175 */ 176 struct netfs_io_request { 177 struct work_struct work; 178 struct inode *inode; /* The file being accessed */ 179 struct address_space *mapping; /* The mapping being accessed */ 180 struct netfs_cache_resources cache_resources; 181 struct list_head subrequests; /* Contributory I/O operations */ 182 void *netfs_priv; /* Private data for the netfs */ 183 unsigned int debug_id; 184 atomic_t nr_outstanding; /* Number of ops in progress */ 185 atomic_t nr_copy_ops; /* Number of copy-to-cache ops in progress */ 186 size_t submitted; /* Amount submitted for I/O so far */ 187 size_t len; /* Length of the request */ 188 short error; /* 0 or error that occurred */ 189 enum netfs_io_origin origin; /* Origin of the request */ 190 loff_t i_size; /* Size of the file */ 191 loff_t start; /* Start position */ 192 pgoff_t no_unlock_folio; /* Don't unlock this folio after read */ 193 refcount_t ref; 194 unsigned long flags; 195 #define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */ 196 #define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */ 197 #define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */ 198 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */ 199 #define NETFS_RREQ_FAILED 4 /* The request failed */ 200 #define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */ 201 const struct netfs_request_ops *netfs_ops; 202 }; 203 204 /* 205 * Operations the network filesystem can/must provide to the helpers. 206 */ 207 struct netfs_request_ops { 208 int (*init_request)(struct netfs_io_request *rreq, struct file *file); 209 void (*free_request)(struct netfs_io_request *rreq); 210 int (*begin_cache_operation)(struct netfs_io_request *rreq); 211 212 void (*expand_readahead)(struct netfs_io_request *rreq); 213 bool (*clamp_length)(struct netfs_io_subrequest *subreq); 214 void (*issue_read)(struct netfs_io_subrequest *subreq); 215 bool (*is_still_valid)(struct netfs_io_request *rreq); 216 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, 217 struct folio **foliop, void **_fsdata); 218 void (*done)(struct netfs_io_request *rreq); 219 }; 220 221 /* 222 * How to handle reading from a hole. 223 */ 224 enum netfs_read_from_hole { 225 NETFS_READ_HOLE_IGNORE, 226 NETFS_READ_HOLE_CLEAR, 227 NETFS_READ_HOLE_FAIL, 228 }; 229 230 /* 231 * Table of operations for access to a cache. This is obtained by 232 * rreq->ops->begin_cache_operation(). 233 */ 234 struct netfs_cache_ops { 235 /* End an operation */ 236 void (*end_operation)(struct netfs_cache_resources *cres); 237 238 /* Read data from the cache */ 239 int (*read)(struct netfs_cache_resources *cres, 240 loff_t start_pos, 241 struct iov_iter *iter, 242 enum netfs_read_from_hole read_hole, 243 netfs_io_terminated_t term_func, 244 void *term_func_priv); 245 246 /* Write data to the cache */ 247 int (*write)(struct netfs_cache_resources *cres, 248 loff_t start_pos, 249 struct iov_iter *iter, 250 netfs_io_terminated_t term_func, 251 void *term_func_priv); 252 253 /* Expand readahead request */ 254 void (*expand_readahead)(struct netfs_cache_resources *cres, 255 loff_t *_start, size_t *_len, loff_t i_size); 256 257 /* Prepare a read operation, shortening it to a cached/uncached 258 * boundary as appropriate. 259 */ 260 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq, 261 loff_t i_size); 262 263 /* Prepare a write operation, working out what part of the write we can 264 * actually do. 265 */ 266 int (*prepare_write)(struct netfs_cache_resources *cres, 267 loff_t *_start, size_t *_len, loff_t i_size, 268 bool no_space_allocated_yet); 269 270 /* Prepare an on-demand read operation, shortening it to a cached/uncached 271 * boundary as appropriate. 272 */ 273 enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres, 274 loff_t start, size_t *_len, 275 loff_t i_size, 276 unsigned long *_flags, ino_t ino); 277 278 /* Query the occupancy of the cache in a region, returning where the 279 * next chunk of data starts and how long it is. 280 */ 281 int (*query_occupancy)(struct netfs_cache_resources *cres, 282 loff_t start, size_t len, size_t granularity, 283 loff_t *_data_start, size_t *_data_len); 284 }; 285 286 struct readahead_control; 287 void netfs_readahead(struct readahead_control *); 288 int netfs_read_folio(struct file *, struct folio *); 289 int netfs_write_begin(struct netfs_inode *, struct file *, 290 struct address_space *, loff_t pos, unsigned int len, 291 struct folio **, void **fsdata); 292 293 void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool); 294 void netfs_get_subrequest(struct netfs_io_subrequest *subreq, 295 enum netfs_sreq_ref_trace what); 296 void netfs_put_subrequest(struct netfs_io_subrequest *subreq, 297 bool was_async, enum netfs_sreq_ref_trace what); 298 void netfs_stats_show(struct seq_file *); 299 300 /** 301 * netfs_inode - Get the netfs inode context from the inode 302 * @inode: The inode to query 303 * 304 * Get the netfs lib inode context from the network filesystem's inode. The 305 * context struct is expected to directly follow on from the VFS inode struct. 306 */ 307 static inline struct netfs_inode *netfs_inode(struct inode *inode) 308 { 309 return container_of(inode, struct netfs_inode, inode); 310 } 311 312 /** 313 * netfs_inode_init - Initialise a netfslib inode context 314 * @ctx: The netfs inode to initialise 315 * @ops: The netfs's operations list 316 * 317 * Initialise the netfs library context struct. This is expected to follow on 318 * directly from the VFS inode struct. 319 */ 320 static inline void netfs_inode_init(struct netfs_inode *ctx, 321 const struct netfs_request_ops *ops) 322 { 323 ctx->ops = ops; 324 ctx->remote_i_size = i_size_read(&ctx->inode); 325 #if IS_ENABLED(CONFIG_FSCACHE) 326 ctx->cache = NULL; 327 #endif 328 } 329 330 /** 331 * netfs_resize_file - Note that a file got resized 332 * @ctx: The netfs inode being resized 333 * @new_i_size: The new file size 334 * 335 * Inform the netfs lib that a file got resized so that it can adjust its state. 336 */ 337 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size) 338 { 339 ctx->remote_i_size = new_i_size; 340 } 341 342 /** 343 * netfs_i_cookie - Get the cache cookie from the inode 344 * @ctx: The netfs inode to query 345 * 346 * Get the caching cookie (if enabled) from the network filesystem's inode. 347 */ 348 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx) 349 { 350 #if IS_ENABLED(CONFIG_FSCACHE) 351 return ctx->cache; 352 #else 353 return NULL; 354 #endif 355 } 356 357 #endif /* _LINUX_NETFS_H */ 358