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 23 enum netfs_sreq_ref_trace; 24 typedef struct mempool mempool_t; 25 struct 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 */ 36 static 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 43 enum 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 53 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error); 54 55 /* 56 * Per-inode context. This wraps the VFS inode. 57 */ 58 struct 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 list_head wb_queue; /* Queue of processes wanting to do writeback */ 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 spinlock_t lock; /* Lock covering wb_queue */ 69 atomic_t io_count; /* Number of outstanding reqs */ 70 unsigned long flags; 71 #define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */ 72 #define NETFS_ICTX_UNBUFFERED 1 /* I/O should not use the pagecache */ 73 #define NETFS_ICTX_WB_LOCK 2 /* Writeback serialisation lock */ 74 #define NETFS_ICTX_MODIFIED_ATTR 3 /* Indicate change in mtime/ctime */ 75 #define NETFS_ICTX_SINGLE_NO_UPLOAD 4 /* Monolithic payload, cache but no upload */ 76 }; 77 78 /* 79 * A netfs group - for instance a ceph snap. This is marked on dirty pages and 80 * pages marked with a group must be flushed before they can be written under 81 * the domain of another group. 82 */ 83 struct netfs_group { 84 refcount_t ref; 85 void (*free)(struct netfs_group *netfs_group); 86 }; 87 88 /* 89 * Information about a dirty page (attached only if necessary). 90 * folio->private 91 */ 92 struct netfs_folio { 93 struct netfs_group *netfs_group; /* Filesystem's grouping marker (or NULL). */ 94 unsigned int dirty_offset; /* Write-streaming dirty data offset */ 95 unsigned int dirty_len; /* Write-streaming dirty data length */ 96 }; 97 #define NETFS_FOLIO_INFO 0x1UL /* OR'd with folio->private. */ 98 #define NETFS_FOLIO_COPY_TO_CACHE ((struct netfs_group *)0x356UL) /* Write to the cache only */ 99 100 static inline bool netfs_is_folio_info(const void *priv) 101 { 102 return (unsigned long)priv & NETFS_FOLIO_INFO; 103 } 104 105 static inline struct netfs_folio *__netfs_folio_info(const void *priv) 106 { 107 if (netfs_is_folio_info(priv)) 108 return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO); 109 return NULL; 110 } 111 112 static inline struct netfs_folio *netfs_folio_info(struct folio *folio) 113 { 114 return __netfs_folio_info(folio_get_private(folio)); 115 } 116 117 static inline struct netfs_group *netfs_folio_group(struct folio *folio) 118 { 119 struct netfs_folio *finfo; 120 void *priv = folio_get_private(folio); 121 122 finfo = netfs_folio_info(folio); 123 if (finfo) 124 return finfo->netfs_group; 125 return priv; 126 } 127 128 /* 129 * Stream of I/O subrequests going to a particular destination, such as the 130 * server or the local cache. This is mainly intended for writing where we may 131 * have to write to multiple destinations concurrently. 132 */ 133 struct netfs_io_stream { 134 /* Submission tracking */ 135 struct netfs_io_subrequest *construct; /* Op being constructed */ 136 size_t sreq_max_len; /* Maximum size of a subrequest */ 137 unsigned int sreq_max_segs; /* 0 or max number of segments in an iterator */ 138 unsigned int submit_off; /* Folio offset we're submitting from */ 139 unsigned int submit_len; /* Amount of data left to submit */ 140 unsigned int submit_extendable_to; /* Amount I/O can be rounded up to */ 141 void (*prepare_write)(struct netfs_io_subrequest *subreq); 142 void (*issue_write)(struct netfs_io_subrequest *subreq); 143 /* Collection tracking */ 144 struct list_head subrequests; /* Contributory I/O operations */ 145 unsigned long long collected_to; /* Position we've collected results to */ 146 size_t transferred; /* The amount transferred from this stream */ 147 unsigned short error; /* Aggregate error for the stream */ 148 enum netfs_io_source source; /* Where to read from/write to */ 149 unsigned char stream_nr; /* Index of stream in parent table */ 150 bool avail; /* T if stream is available */ 151 bool active; /* T if stream is active */ 152 bool need_retry; /* T if this stream needs retrying */ 153 bool failed; /* T if this stream failed */ 154 bool transferred_valid; /* T is ->transferred is valid */ 155 }; 156 157 /* 158 * Resources required to do operations on a cache. 159 */ 160 struct netfs_cache_resources { 161 const struct netfs_cache_ops *ops; 162 void *cache_priv; 163 void *cache_priv2; 164 unsigned int debug_id; /* Cookie debug ID */ 165 unsigned int inval_counter; /* object->inval_counter at begin_op */ 166 }; 167 168 /* 169 * Descriptor for a single component subrequest. Each operation represents an 170 * individual read/write from/to a server, a cache, a journal, etc.. 171 * 172 * The buffer iterator is persistent for the life of the subrequest struct and 173 * the pages it points to can be relied on to exist for the duration. 174 */ 175 struct netfs_io_subrequest { 176 struct netfs_io_request *rreq; /* Supervising I/O request */ 177 struct work_struct work; 178 struct list_head rreq_link; /* Link in rreq->subrequests */ 179 struct iov_iter io_iter; /* Iterator for this subrequest */ 180 unsigned long long start; /* Where to start the I/O */ 181 size_t len; /* Size of the I/O */ 182 size_t transferred; /* Amount of data transferred */ 183 refcount_t ref; 184 short error; /* 0 or error that occurred */ 185 unsigned short debug_index; /* Index in list (for debugging output) */ 186 unsigned int nr_segs; /* Number of segs in io_iter */ 187 u8 retry_count; /* The number of retries (0 on initial pass) */ 188 enum netfs_io_source source; /* Where to read from/write to */ 189 unsigned char stream_nr; /* I/O stream this belongs to */ 190 unsigned long flags; 191 #define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */ 192 #define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */ 193 #define NETFS_SREQ_MADE_PROGRESS 4 /* Set if we transferred at least some data */ 194 #define NETFS_SREQ_BOUNDARY 6 /* Set if ends on hard boundary (eg. ceph object) */ 195 #define NETFS_SREQ_HIT_EOF 7 /* Set if short due to EOF */ 196 #define NETFS_SREQ_IN_PROGRESS 8 /* Unlocked when the subrequest completes */ 197 #define NETFS_SREQ_NEED_RETRY 9 /* Set if the filesystem requests a retry */ 198 #define NETFS_SREQ_FAILED 10 /* Set if the subreq failed unretryably */ 199 }; 200 201 enum netfs_io_origin { 202 NETFS_READAHEAD, /* This read was triggered by readahead */ 203 NETFS_READPAGE, /* This read is a synchronous read */ 204 NETFS_READ_GAPS, /* This read is a synchronous read to fill gaps */ 205 NETFS_READ_SINGLE, /* This read should be treated as a single object */ 206 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */ 207 NETFS_UNBUFFERED_READ, /* This is an unbuffered read */ 208 NETFS_DIO_READ, /* This is a direct I/O read */ 209 NETFS_WRITEBACK, /* This write was triggered by writepages */ 210 NETFS_WRITEBACK_SINGLE, /* This monolithic write was triggered by writepages */ 211 NETFS_WRITETHROUGH, /* This write was made by netfs_perform_write() */ 212 NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */ 213 NETFS_DIO_WRITE, /* This is a direct I/O write */ 214 NETFS_PGPRIV2_COPY_TO_CACHE, /* [DEPRECATED] This is writing read data to the cache */ 215 nr__netfs_io_origin 216 } __mode(byte); 217 218 /* 219 * Descriptor for an I/O helper request. This is used to make multiple I/O 220 * operations to a variety of data stores and then stitch the result together. 221 */ 222 struct netfs_io_request { 223 union { 224 struct work_struct cleanup_work; /* Deferred cleanup work */ 225 struct rcu_head rcu; 226 }; 227 struct work_struct work; /* Result collector work */ 228 struct inode *inode; /* The file being accessed */ 229 struct address_space *mapping; /* The mapping being accessed */ 230 struct kiocb *iocb; /* AIO completion vector */ 231 struct netfs_cache_resources cache_resources; 232 struct netfs_io_request *copy_to_cache; /* Request to write just-read data to the cache */ 233 #ifdef CONFIG_PROC_FS 234 struct list_head proc_link; /* Link in netfs_iorequests */ 235 #endif 236 struct netfs_io_stream io_streams[2]; /* Streams of parallel I/O operations */ 237 #define NR_IO_STREAMS 2 //wreq->nr_io_streams 238 struct netfs_group *group; /* Writeback group being written back */ 239 struct rolling_buffer buffer; /* Unencrypted buffer */ 240 #define NETFS_ROLLBUF_PUT_MARK ROLLBUF_MARK_1 241 #define NETFS_ROLLBUF_PAGECACHE_MARK ROLLBUF_MARK_2 242 wait_queue_head_t waitq; /* Processor waiter */ 243 void *netfs_priv; /* Private data for the netfs */ 244 void *netfs_priv2; /* Private data for the netfs */ 245 struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */ 246 unsigned long long submitted; /* Amount submitted for I/O so far */ 247 unsigned long long len; /* Length of the request */ 248 size_t transferred; /* Amount to be indicated as transferred */ 249 size_t progress_at; /* Report read progress when hit this much read */ 250 long error; /* 0 or error that occurred */ 251 unsigned long long i_size; /* Size of the file */ 252 unsigned long long start; /* Start position */ 253 atomic64_t issued_to; /* Write issuer folio cursor */ 254 unsigned long long collected_to; /* Point we've collected to */ 255 unsigned long long cleaned_to; /* Position we've cleaned folios to */ 256 unsigned long long abandon_to; /* Position to abandon folios to */ 257 const struct folio *no_unlock_folio; /* Don't unlock this folio after read */ 258 gfp_t gfp; /* GFP flags to use */ 259 unsigned int direct_bv_count; /* Number of elements in direct_bv[] */ 260 unsigned int debug_id; 261 unsigned int rsize; /* Maximum read size (0 for none) */ 262 unsigned int wsize; /* Maximum write size (0 for none) */ 263 atomic_t subreq_counter; /* Next subreq->debug_index */ 264 unsigned int nr_group_rel; /* Number of refs to release on ->group */ 265 spinlock_t lock; /* Lock for queuing subreqs */ 266 enum netfs_io_origin origin; /* Origin of the request */ 267 bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */ 268 refcount_t ref; 269 unsigned long flags; 270 #define NETFS_RREQ_IN_PROGRESS 0 /* Unlocked when the request completes (has ref) */ 271 #define NETFS_RREQ_ALL_QUEUED 1 /* All subreqs are now queued */ 272 #define NETFS_RREQ_PAUSE 2 /* Pause subrequest generation */ 273 #define NETFS_RREQ_FAILED 3 /* The request failed */ 274 #define NETFS_RREQ_RETRYING 4 /* Set if we're in the retry path */ 275 #define NETFS_RREQ_SHORT_TRANSFER 5 /* Set if we have a short transfer */ 276 #define NETFS_RREQ_OFFLOAD_COLLECTION 8 /* Offload collection to workqueue */ 277 #define NETFS_RREQ_NO_UNLOCK_FOLIO 9 /* Don't unlock no_unlock_folio on completion */ 278 #define NETFS_RREQ_CANCEL_CACHING 10 /* Set to cancel caching */ 279 #define NETFS_RREQ_UPLOAD_TO_SERVER 11 /* Need to write to the server */ 280 #define NETFS_RREQ_USE_IO_ITER 12 /* Use ->io_iter rather than ->i_pages */ 281 #define NETFS_RREQ_NEED_PUT_RA_REFS 17 /* Need to put the folio refs RA gave us */ 282 #define NETFS_RREQ_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark 283 * write to cache on read */ 284 const struct netfs_request_ops *netfs_ops; 285 }; 286 287 /* 288 * Operations the network filesystem can/must provide to the helpers. 289 */ 290 struct netfs_request_ops { 291 mempool_t *request_pool; 292 mempool_t *subrequest_pool; 293 int (*init_request)(struct netfs_io_request *rreq, struct file *file); 294 void (*free_request)(struct netfs_io_request *rreq); 295 void (*free_subrequest)(struct netfs_io_subrequest *rreq); 296 297 /* Read request handling */ 298 void (*expand_readahead)(struct netfs_io_request *rreq); 299 int (*prepare_read)(struct netfs_io_subrequest *subreq); 300 void (*issue_read)(struct netfs_io_subrequest *subreq); 301 bool (*is_still_valid)(struct netfs_io_request *rreq); 302 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, 303 struct folio **foliop, void **_fsdata); 304 void (*done)(struct netfs_io_request *rreq); 305 306 /* Modification handling */ 307 void (*update_i_size)(struct inode *inode, loff_t i_size); 308 void (*post_modify)(struct inode *inode); 309 310 /* Write request handling */ 311 void (*begin_writeback)(struct netfs_io_request *wreq); 312 void (*prepare_write)(struct netfs_io_subrequest *subreq); 313 void (*issue_write)(struct netfs_io_subrequest *subreq); 314 void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream); 315 void (*invalidate_cache)(struct netfs_io_request *wreq); 316 }; 317 318 /* 319 * How to handle reading from a hole. 320 */ 321 enum netfs_read_from_hole { 322 NETFS_READ_HOLE_IGNORE, 323 NETFS_READ_HOLE_FAIL, 324 }; 325 326 /* 327 * Table of operations for access to a cache. 328 */ 329 struct netfs_cache_ops { 330 /* End an operation */ 331 void (*end_operation)(struct netfs_cache_resources *cres); 332 333 /* Read data from the cache */ 334 int (*read)(struct netfs_cache_resources *cres, 335 loff_t start_pos, 336 struct iov_iter *iter, 337 enum netfs_read_from_hole read_hole, 338 netfs_io_terminated_t term_func, 339 void *term_func_priv); 340 341 /* Write data to the cache */ 342 int (*write)(struct netfs_cache_resources *cres, 343 loff_t start_pos, 344 struct iov_iter *iter, 345 netfs_io_terminated_t term_func, 346 void *term_func_priv); 347 348 /* Write data to the cache from a netfs subrequest. */ 349 void (*issue_write)(struct netfs_io_subrequest *subreq); 350 351 /* Expand readahead request */ 352 void (*expand_readahead)(struct netfs_cache_resources *cres, 353 unsigned long long *_start, 354 unsigned long long *_len, 355 unsigned long long i_size); 356 357 /* Prepare a read operation, shortening it to a cached/uncached 358 * boundary as appropriate. 359 */ 360 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq, 361 unsigned long long i_size); 362 363 /* Prepare a write subrequest, working out if we're allowed to do it 364 * and finding out the maximum amount of data to gather before 365 * attempting to submit. If we're not permitted to do it, the 366 * subrequest should be marked failed. 367 */ 368 void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq); 369 370 /* Prepare a write operation, working out what part of the write we can 371 * actually do. 372 */ 373 int (*prepare_write)(struct netfs_cache_resources *cres, 374 loff_t *_start, size_t *_len, size_t upper_len, 375 loff_t i_size, bool no_space_allocated_yet); 376 377 /* Query the occupancy of the cache in a region, returning where the 378 * next chunk of data starts and how long it is. 379 */ 380 int (*query_occupancy)(struct netfs_cache_resources *cres, 381 loff_t start, size_t len, size_t granularity, 382 loff_t *_data_start, size_t *_data_len); 383 }; 384 385 /* High-level read API. */ 386 ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter); 387 ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter); 388 ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter); 389 ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter); 390 391 /* High-level write API */ 392 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter, 393 struct netfs_group *netfs_group); 394 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from, 395 struct netfs_group *netfs_group); 396 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from); 397 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter, 398 struct netfs_group *netfs_group); 399 ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from); 400 void netfs_clear_stale_post_isize(struct inode *inode, uoff_t from, 401 uoff_t to); 402 403 /* Single, monolithic object read/write API. */ 404 void netfs_single_mark_inode_dirty(struct inode *inode); 405 ssize_t netfs_read_single(struct inode *inode, struct file *file, struct iov_iter *iter); 406 int netfs_writeback_single(struct address_space *mapping, 407 struct writeback_control *wbc, 408 struct iov_iter *iter); 409 410 /* Address operations API */ 411 struct readahead_control; 412 void netfs_readahead(struct readahead_control *); 413 int netfs_read_folio(struct file *, struct folio *); 414 int netfs_write_begin(struct netfs_inode *, struct file *, 415 struct address_space *, loff_t pos, unsigned int len, 416 struct folio **, void **fsdata); 417 int netfs_writepages(struct address_space *mapping, 418 struct writeback_control *wbc); 419 bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio); 420 int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc); 421 void netfs_clear_inode_writeback(struct inode *inode, const void *aux); 422 void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length); 423 bool netfs_release_folio(struct folio *folio, gfp_t gfp); 424 425 /* VMA operations API. */ 426 vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group); 427 428 /* (Sub)request management API. */ 429 void netfs_read_subreq_progress(struct netfs_io_subrequest *subreq); 430 void netfs_read_subreq_terminated(struct netfs_io_subrequest *subreq); 431 void netfs_get_subrequest(struct netfs_io_subrequest *subreq, 432 enum netfs_sreq_ref_trace what); 433 void netfs_put_subrequest(struct netfs_io_subrequest *subreq, 434 enum netfs_sreq_ref_trace what); 435 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len, 436 struct iov_iter *new, 437 iov_iter_extraction_t extraction_flags); 438 size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset, 439 size_t max_size, size_t max_segs); 440 void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq); 441 void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error); 442 443 int netfs_start_io_read(struct inode *inode); 444 void netfs_end_io_read(struct inode *inode); 445 int netfs_start_io_write(struct inode *inode); 446 void netfs_end_io_write(struct inode *inode); 447 int netfs_start_io_direct(struct inode *inode); 448 void netfs_end_io_direct(struct inode *inode); 449 450 /* Miscellaneous APIs. */ 451 struct folio_queue *netfs_folioq_alloc(unsigned int rreq_id, gfp_t gfp, 452 unsigned int trace /*enum netfs_folioq_trace*/); 453 void netfs_folioq_free(struct folio_queue *folioq, 454 unsigned int trace /*enum netfs_trace_folioq*/); 455 456 /* Buffer wrangling helpers API. */ 457 int netfs_alloc_folioq_buffer(struct address_space *mapping, 458 struct folio_queue **_buffer, 459 size_t *_cur_size, ssize_t size, gfp_t gfp); 460 void netfs_free_folioq_buffer(struct folio_queue *fq); 461 462 /* Writeback exclusion API. */ 463 bool netfs_wb_begin(struct netfs_inode *ictx, bool nowait); 464 void netfs_wb_end(struct netfs_inode *ictx); 465 466 /** 467 * netfs_inode - Get the netfs inode context from the inode 468 * @inode: The inode to query 469 * 470 * Get the netfs lib inode context from the network filesystem's inode. The 471 * context struct is expected to directly follow on from the VFS inode struct. 472 */ 473 static inline struct netfs_inode *netfs_inode(struct inode *inode) 474 { 475 return container_of(inode, struct netfs_inode, inode); 476 } 477 478 /** 479 * netfs_read_remote_i_size - Read remote_i_size safely 480 * @inode: The inode to access 481 * 482 * Read remote_i_size safely without the potential for tearing on 32-bit 483 * arches. 484 * 485 * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the 486 * i_size_read/write must be atomic with respect to the local cpu (unlike with 487 * preempt disabled), but they don't need to be atomic with respect to other 488 * cpus like in true SMP (so they need either to either locally disable irq 489 * around the read or for example on x86 they can be still implemented as a 490 * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit 491 * archs it makes no difference if preempt is enabled or not. 492 */ 493 static inline unsigned long long netfs_read_remote_i_size(const struct inode *inode) 494 { 495 const struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode); 496 unsigned long long remote_i_size; 497 498 #if BITS_PER_LONG==32 && defined(CONFIG_SMP) 499 unsigned int seq; 500 501 do { 502 seq = read_seqcount_begin(&inode->i_size_seqcount); 503 remote_i_size = ictx->_remote_i_size; 504 } while (read_seqcount_retry(&inode->i_size_seqcount, seq)); 505 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) 506 preempt_disable(); 507 remote_i_size = ictx->_remote_i_size; 508 preempt_enable(); 509 #else 510 /* Pairs with smp_store_release() in netfs_write_remote_i_size() */ 511 remote_i_size = smp_load_acquire(&ictx->_remote_i_size); 512 #endif 513 return remote_i_size; 514 } 515 516 /* 517 * netfs_write_remote_i_size - Set remote_i_size safely 518 * @inode: The inode to access 519 * @remote_i_size: The new value for the size of the file on the server 520 * 521 * Set remote_i_size safely without the potential for tearing on 32-bit arches. 522 * 523 * Context: The caller must hold inode->i_lock. 524 * 525 * NOTE: unlike netfs_read_remote_i_size(), netfs_write_remote_i_size() does 526 * need locking around it (normally i_rwsem), otherwise on 32bit/SMP an update 527 * of i_size_seqcount can be lost, resulting in subsequent i_size_read() calls 528 * spinning forever. 529 */ 530 static inline void netfs_write_remote_i_size(struct inode *inode, 531 unsigned long long remote_i_size) 532 { 533 struct netfs_inode *ictx = netfs_inode(inode); 534 535 #if BITS_PER_LONG==32 && defined(CONFIG_SMP) 536 write_seqcount_begin(&inode->i_size_seqcount); 537 ictx->_remote_i_size = remote_i_size; 538 write_seqcount_end(&inode->i_size_seqcount); 539 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) 540 preempt_disable(); 541 ictx->_remote_i_size = remote_i_size; 542 preempt_enable(); 543 #else 544 /* 545 * Pairs with smp_load_acquire() in netfs_read_remote_i_size() to 546 * ensure changes related to inode size (such as page contents) are 547 * visible before we see the changed inode size. 548 */ 549 smp_store_release(&ictx->_remote_i_size, remote_i_size); 550 #endif 551 } 552 553 /** 554 * netfs_read_zero_point - Read zero_point safely 555 * @inode: The inode to access 556 * 557 * Read zero_point safely without the potential for tearing on 32-bit 558 * arches. 559 * 560 * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the 561 * i_size_read/write must be atomic with respect to the local cpu (unlike with 562 * preempt disabled), but they don't need to be atomic with respect to other 563 * cpus like in true SMP (so they need either to either locally disable irq 564 * around the read or for example on x86 they can be still implemented as a 565 * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit 566 * archs it makes no difference if preempt is enabled or not. 567 */ 568 static inline unsigned long long netfs_read_zero_point(const struct inode *inode) 569 { 570 struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode); 571 unsigned long long zero_point; 572 573 #if BITS_PER_LONG==32 && defined(CONFIG_SMP) 574 unsigned int seq; 575 576 do { 577 seq = read_seqcount_begin(&inode->i_size_seqcount); 578 zero_point = ictx->_zero_point; 579 } while (read_seqcount_retry(&inode->i_size_seqcount, seq)); 580 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) 581 preempt_disable(); 582 zero_point = ictx->_zero_point; 583 preempt_enable(); 584 #else 585 /* Pairs with smp_store_release() in netfs_write_zero_point() */ 586 zero_point = smp_load_acquire(&ictx->_zero_point); 587 #endif 588 return zero_point; 589 } 590 591 /* 592 * netfs_write_zero_point - Set zero_point safely 593 * @inode: The inode to access 594 * @zero_point: The new value for the point beyond which the server has no data 595 * 596 * Set zero_point safely without the potential for tearing on 32-bit arches. 597 * 598 * Context: The caller must hold inode->i_lock. 599 * 600 * NOTE: unlike netfs_read_zero_point(), netfs_write_zero_point() does need 601 * locking around it (normally i_rwsem), otherwise on 32bit/SMP an update of 602 * i_size_seqcount can be lost, resulting in subsequent read calls spinning 603 * forever. 604 */ 605 static inline void netfs_write_zero_point(struct inode *inode, 606 unsigned long long zero_point) 607 { 608 struct netfs_inode *ictx = netfs_inode(inode); 609 610 #if BITS_PER_LONG==32 && defined(CONFIG_SMP) 611 write_seqcount_begin(&inode->i_size_seqcount); 612 ictx->_zero_point = zero_point; 613 write_seqcount_end(&inode->i_size_seqcount); 614 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) 615 preempt_disable(); 616 ictx->_zero_point = zero_point; 617 preempt_enable(); 618 #else 619 /* 620 * Pairs with smp_load_acquire() in netfs_read_zero_point() to 621 * ensure changes related to inode size (such as page contents) are 622 * visible before we see the changed inode size. 623 */ 624 smp_store_release(&ictx->_zero_point, zero_point); 625 #endif 626 } 627 628 /** 629 * netfs_read_sizes - Read remote_i_size and zero_point safely 630 * @inode: The inode to access 631 * @i_size: Where to return the local file size. 632 * @remote_i_size: Where to return the size of the file on the server 633 * @zero_point: Where to return the the point beyond which the server has no data 634 * 635 * Read remote_i_size and zero_point safely without the potential for tearing 636 * on 32-bit arches. 637 * 638 * NOTE: in a 32bit arch with a preemptable kernel and an UP compile the 639 * i_size_read/write must be atomic with respect to the local cpu (unlike with 640 * preempt disabled), but they don't need to be atomic with respect to other 641 * cpus like in true SMP (so they need either to either locally disable irq 642 * around the read or for example on x86 they can be still implemented as a 643 * cmpxchg8b without the need of the lock prefix). For SMP compiles and 64bit 644 * archs it makes no difference if preempt is enabled or not. 645 */ 646 static inline void netfs_read_sizes(const struct inode *inode, 647 unsigned long long *i_size, 648 unsigned long long *remote_i_size, 649 unsigned long long *zero_point) 650 { 651 const struct netfs_inode *ictx = container_of(inode, struct netfs_inode, inode); 652 #if BITS_PER_LONG==32 && defined(CONFIG_SMP) 653 unsigned int seq; 654 655 do { 656 seq = read_seqcount_begin(&inode->i_size_seqcount); 657 *i_size = inode->i_size; 658 *remote_i_size = ictx->_remote_i_size; 659 *zero_point = ictx->_zero_point; 660 } while (read_seqcount_retry(&inode->i_size_seqcount, seq)); 661 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) 662 preempt_disable(); 663 *i_size = inode->i_size; 664 *remote_i_size = ictx->_remote_i_size; 665 *zero_point = ictx->_zero_point; 666 preempt_enable(); 667 #else 668 /* Pairs with smp_store_release() in i_size_write() */ 669 *i_size = smp_load_acquire(&inode->i_size); 670 /* Pairs with smp_store_release() in netfs_write_remote_i_size() */ 671 *remote_i_size = smp_load_acquire(&ictx->_remote_i_size); 672 /* Pairs with smp_store_release() in netfs_write_zero_point() */ 673 *zero_point = smp_load_acquire(&ictx->_zero_point); 674 #endif 675 } 676 677 /* 678 * netfs_write_sizes - Set i_size, remote_i_size and zero_point safely 679 * @inode: The inode to access 680 * @i_size: The new value for the local size of the file 681 * @remote_i_size: The new value for the size of the file on the server 682 * @zero_point: The new value for the point beyond which the server has no data 683 * 684 * Set both remote_i_size and zero_point safely without the potential for 685 * tearing on 32-bit arches. 686 * 687 * Context: The caller must hold inode->i_lock. 688 * 689 * NOTE: unlike netfs_read_zero_point(), netfs_write_zero_point() does need 690 * locking around it (normally i_rwsem), otherwise on 32bit/SMP an update of 691 * i_size_seqcount can be lost, resulting in subsequent read calls spinning 692 * forever. 693 */ 694 static inline void netfs_write_sizes(struct inode *inode, 695 unsigned long long i_size, 696 unsigned long long remote_i_size, 697 unsigned long long zero_point) 698 { 699 struct netfs_inode *ictx = netfs_inode(inode); 700 701 #if BITS_PER_LONG==32 && defined(CONFIG_SMP) 702 write_seqcount_begin(&inode->i_size_seqcount); 703 inode->i_size = i_size; 704 ictx->_remote_i_size = remote_i_size; 705 ictx->_zero_point = zero_point; 706 write_seqcount_end(&inode->i_size_seqcount); 707 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) 708 preempt_disable(); 709 inode->i_size = i_size; 710 ictx->_remote_i_size = remote_i_size; 711 ictx->_zero_point = zero_point; 712 preempt_enable(); 713 #else 714 /* 715 * Pairs with smp_load_acquire() in i_size_read(), 716 * netfs_read_remote_i_size() and netfs_read_zero_point() to ensure 717 * changes related to inode size (such as page contents) are visible 718 * before we see the changed inode size. 719 */ 720 smp_store_release(&inode->i_size, i_size); 721 smp_store_release(&ictx->_remote_i_size, remote_i_size); 722 smp_store_release(&ictx->_zero_point, zero_point); 723 #endif 724 } 725 726 /** 727 * netfs_inode_init - Initialise a netfslib inode context 728 * @ctx: The netfs inode to initialise 729 * @ops: The netfs's operations list 730 * @use_zero_point: True to use the zero_point read optimisation 731 * 732 * Initialise the netfs library context struct. This is expected to follow on 733 * directly from the VFS inode struct. 734 */ 735 static inline void netfs_inode_init(struct netfs_inode *ctx, 736 const struct netfs_request_ops *ops, 737 bool use_zero_point) 738 { 739 ctx->ops = ops; 740 ctx->_remote_i_size = i_size_read(&ctx->inode); 741 ctx->_zero_point = LLONG_MAX; 742 ctx->flags = 0; 743 atomic_set(&ctx->io_count, 0); 744 #if IS_ENABLED(CONFIG_FSCACHE) 745 ctx->cache = NULL; 746 #endif 747 INIT_LIST_HEAD(&ctx->wb_queue); 748 spin_lock_init(&ctx->lock); 749 /* ->releasepage() drives zero_point */ 750 if (use_zero_point) { 751 ctx->_zero_point = ctx->_remote_i_size; 752 mapping_set_release_always(ctx->inode.i_mapping); 753 } 754 } 755 756 /** 757 * netfs_resize_file - Note that a file got resized 758 * @ictx: The netfs inode being resized 759 * @new_i_size: The new file size 760 * @changed_on_server: The change was applied to the server 761 * 762 * Inform the netfs lib that a file got resized so that it can adjust its state. 763 */ 764 static inline void netfs_resize_file(struct netfs_inode *ictx, 765 unsigned long long new_i_size, 766 bool changed_on_server) 767 { 768 #if BITS_PER_LONG==32 && defined(CONFIG_SMP) 769 struct inode *inode = &ictx->inode; 770 771 preempt_disable(); 772 write_seqcount_begin(&inode->i_size_seqcount); 773 if (changed_on_server) 774 ictx->_remote_i_size = new_i_size; 775 if (new_i_size < ictx->_zero_point) 776 ictx->_zero_point = new_i_size; 777 write_seqcount_end(&inode->i_size_seqcount); 778 preempt_enable(); 779 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION) 780 preempt_disable(); 781 if (changed_on_server) 782 ictx->_remote_i_size = new_i_size; 783 if (new_i_size < ictx->_zero_point) 784 ictx->_zero_point = new_i_size; 785 preempt_enable(); 786 #else 787 /* 788 * Pairs with smp_load_acquire() in netfs_read_remote_i_size and 789 * netfs_read_zero_point() to ensure changes related to inode size 790 * (such as page contents) are visible before we see the changed inode 791 * size. 792 */ 793 if (changed_on_server) 794 smp_store_release(&ictx->_remote_i_size, new_i_size); 795 if (new_i_size < ictx->_zero_point) 796 smp_store_release(&ictx->_zero_point, new_i_size); 797 #endif 798 } 799 800 /** 801 * netfs_i_cookie - Get the cache cookie from the inode 802 * @ctx: The netfs inode to query 803 * 804 * Get the caching cookie (if enabled) from the network filesystem's inode. 805 */ 806 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx) 807 { 808 #if IS_ENABLED(CONFIG_FSCACHE) 809 return ctx->cache; 810 #else 811 return NULL; 812 #endif 813 } 814 815 /** 816 * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete 817 * @inode: The netfs inode to wait on 818 * 819 * Wait for outstanding I/O requests of any type to complete. This is intended 820 * to be called from inode eviction routines. This makes sure that any 821 * resources held by those requests are cleaned up before we let the inode get 822 * cleaned up. 823 */ 824 static inline void netfs_wait_for_outstanding_io(struct inode *inode) 825 { 826 struct netfs_inode *ictx = netfs_inode(inode); 827 828 wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0); 829 } 830 831 #endif /* _LINUX_NETFS_H */ 832