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 typedef struct mempool_s mempool_t;
24
25 /**
26 * folio_start_private_2 - Start an fscache write on a folio. [DEPRECATED]
27 * @folio: The folio.
28 *
29 * Call this function before writing a folio to a local cache. Starting a
30 * second write before the first one finishes is not allowed.
31 *
32 * Note that this should no longer be used.
33 */
34 static inline void folio_start_private_2(struct folio *folio)
35 {
36 VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
37 folio_get(folio);
38 folio_set_private_2(folio);
39 }
40
41 /* Marks used on xarray-based buffers */
42 #define NETFS_BUF_PUT_MARK XA_MARK_0 /* - Page needs putting */
43 #define NETFS_BUF_PAGECACHE_MARK XA_MARK_1 /* - Page needs wb/dirty flag wrangling */
44
45 enum netfs_io_source {
46 NETFS_FILL_WITH_ZEROES,
47 NETFS_DOWNLOAD_FROM_SERVER,
48 NETFS_READ_FROM_CACHE,
49 NETFS_INVALID_READ,
50 NETFS_UPLOAD_TO_SERVER,
51 NETFS_WRITE_TO_CACHE,
52 NETFS_INVALID_WRITE,
53 } __mode(byte);
54
55 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
56 bool was_async);
57
58 /*
59 * Per-inode context. This wraps the VFS inode.
60 */
61 struct netfs_inode {
62 struct inode inode; /* The VFS inode */
63 const struct netfs_request_ops *ops;
64 #if IS_ENABLED(CONFIG_FSCACHE)
65 struct fscache_cookie *cache;
66 #endif
67 struct mutex wb_lock; /* Writeback serialisation */
68 loff_t remote_i_size; /* Size of the remote file */
69 loff_t zero_point; /* Size after which we assume there's no data
70 * on the server */
71 atomic_t io_count; /* Number of outstanding reqs */
72 unsigned long flags;
73 #define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */
74 #define NETFS_ICTX_UNBUFFERED 1 /* I/O should not use the pagecache */
75 #define NETFS_ICTX_WRITETHROUGH 2 /* Write-through caching */
76 #define NETFS_ICTX_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark
77 * write to cache on read */
78 };
79
80 /*
81 * A netfs group - for instance a ceph snap. This is marked on dirty pages and
82 * pages marked with a group must be flushed before they can be written under
83 * the domain of another group.
84 */
85 struct netfs_group {
86 refcount_t ref;
87 void (*free)(struct netfs_group *netfs_group);
88 };
89
90 /*
91 * Information about a dirty page (attached only if necessary).
92 * folio->private
93 */
94 struct netfs_folio {
95 struct netfs_group *netfs_group; /* Filesystem's grouping marker (or NULL). */
96 unsigned int dirty_offset; /* Write-streaming dirty data offset */
97 unsigned int dirty_len; /* Write-streaming dirty data length */
98 };
99 #define NETFS_FOLIO_INFO 0x1UL /* OR'd with folio->private. */
100 #define NETFS_FOLIO_COPY_TO_CACHE ((struct netfs_group *)0x356UL) /* Write to the cache only */
101
102 static inline bool netfs_is_folio_info(const void *priv)
103 {
104 return (unsigned long)priv & NETFS_FOLIO_INFO;
105 }
106
107 static inline struct netfs_folio *__netfs_folio_info(const void *priv)
108 {
109 if (netfs_is_folio_info(priv))
110 return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO);
111 return NULL;
112 }
113
114 static inline struct netfs_folio *netfs_folio_info(struct folio *folio)
115 {
116 return __netfs_folio_info(folio_get_private(folio));
117 }
118
119 static inline struct netfs_group *netfs_folio_group(struct folio *folio)
120 {
121 struct netfs_folio *finfo;
122 void *priv = folio_get_private(folio);
123
124 finfo = netfs_folio_info(folio);
125 if (finfo)
126 return finfo->netfs_group;
127 return priv;
128 }
129
130 /*
131 * Stream of I/O subrequests going to a particular destination, such as the
132 * server or the local cache. This is mainly intended for writing where we may
133 * have to write to multiple destinations concurrently.
134 */
135 struct netfs_io_stream {
136 /* Submission tracking */
137 struct netfs_io_subrequest *construct; /* Op being constructed */
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_max_len; /* 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 struct netfs_io_subrequest *front; /* Op being collected */
146 unsigned long long collected_to; /* Position we've collected results to */
147 size_t transferred; /* The amount transferred from this stream */
148 enum netfs_io_source source; /* Where to read from/write to */
149 unsigned short error; /* Aggregate error for the stream */
150 unsigned char stream_nr; /* Index of stream in parent table */
151 bool avail; /* T if stream is available */
152 bool active; /* T if stream is active */
153 bool need_retry; /* T if this stream needs retrying */
154 bool failed; /* T if this stream failed */
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 max_len; /* Maximum size of the I/O */
182 size_t len; /* Size of the I/O */
183 size_t transferred; /* Amount of data transferred */
184 refcount_t ref;
185 short error; /* 0 or error that occurred */
186 unsigned short debug_index; /* Index in list (for debugging output) */
187 unsigned int nr_segs; /* Number of segs in io_iter */
188 unsigned int max_nr_segs; /* 0 or max number of segments in an iterator */
189 enum netfs_io_source source; /* Where to read from/write to */
190 unsigned char stream_nr; /* I/O stream this belongs to */
191 unsigned long flags;
192 #define NETFS_SREQ_COPY_TO_CACHE 0 /* Set if should copy the data to the cache */
193 #define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */
194 #define NETFS_SREQ_SHORT_IO 2 /* Set if the I/O was short */
195 #define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */
196 #define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */
197 #define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */
198 #define NETFS_SREQ_BOUNDARY 6 /* Set if ends on hard boundary (eg. ceph object) */
199 #define NETFS_SREQ_IN_PROGRESS 8 /* Unlocked when the subrequest completes */
200 #define NETFS_SREQ_NEED_RETRY 9 /* Set if the filesystem requests a retry */
201 #define NETFS_SREQ_RETRYING 10 /* Set if we're retrying */
202 #define NETFS_SREQ_FAILED 11 /* Set if the subreq failed unretryably */
203 };
204
205 enum netfs_io_origin {
206 NETFS_READAHEAD, /* This read was triggered by readahead */
207 NETFS_READPAGE, /* This read is a synchronous read */
208 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
209 NETFS_COPY_TO_CACHE, /* This write is to copy a read to the cache */
210 NETFS_WRITEBACK, /* This 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_READ, /* This is a direct I/O read */
214 NETFS_DIO_WRITE, /* This is a direct I/O write */
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 work;
225 struct rcu_head rcu;
226 };
227 struct inode *inode; /* The file being accessed */
228 struct address_space *mapping; /* The mapping being accessed */
229 struct kiocb *iocb; /* AIO completion vector */
230 struct netfs_cache_resources cache_resources;
231 struct list_head proc_link; /* Link in netfs_iorequests */
232 struct list_head subrequests; /* Contributory I/O operations */
233 struct netfs_io_stream io_streams[2]; /* Streams of parallel I/O operations */
234 #define NR_IO_STREAMS 2 //wreq->nr_io_streams
235 struct netfs_group *group; /* Writeback group being written back */
236 struct iov_iter iter; /* Unencrypted-side iterator */
237 struct iov_iter io_iter; /* I/O (Encrypted-side) iterator */
238 void *netfs_priv; /* Private data for the netfs */
239 void *netfs_priv2; /* Private data for the netfs */
240 struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */
241 unsigned int direct_bv_count; /* Number of elements in direct_bv[] */
242 unsigned int debug_id;
243 unsigned int rsize; /* Maximum read size (0 for none) */
244 unsigned int wsize; /* Maximum write size (0 for none) */
245 atomic_t subreq_counter; /* Next subreq->debug_index */
246 unsigned int nr_group_rel; /* Number of refs to release on ->group */
247 spinlock_t lock; /* Lock for queuing subreqs */
248 atomic_t nr_outstanding; /* Number of ops in progress */
249 atomic_t nr_copy_ops; /* Number of copy-to-cache ops in progress */
250 size_t upper_len; /* Length can be extended to here */
251 unsigned long long submitted; /* Amount submitted for I/O so far */
252 unsigned long long len; /* Length of the request */
253 size_t transferred; /* Amount to be indicated as transferred */
254 short error; /* 0 or error that occurred */
255 enum netfs_io_origin origin; /* Origin of the request */
256 bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */
257 unsigned long long i_size; /* Size of the file */
258 unsigned long long start; /* Start position */
259 atomic64_t issued_to; /* Write issuer folio cursor */
260 unsigned long long contiguity; /* Tracking for gaps in the writeback sequence */
261 unsigned long long collected_to; /* Point we've collected to */
262 unsigned long long cleaned_to; /* Position we've cleaned folios to */
263 pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
264 refcount_t ref;
265 unsigned long flags;
266 #define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */
267 #define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */
268 #define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */
269 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */
270 #define NETFS_RREQ_FAILED 4 /* The request failed */
271 #define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */
272 #define NETFS_RREQ_WRITE_TO_CACHE 7 /* Need to write to the cache */
273 #define NETFS_RREQ_UPLOAD_TO_SERVER 8 /* Need to write to the server */
274 #define NETFS_RREQ_NONBLOCK 9 /* Don't block if possible (O_NONBLOCK) */
275 #define NETFS_RREQ_BLOCKED 10 /* We blocked */
276 #define NETFS_RREQ_PAUSE 11 /* Pause subrequest generation */
277 #define NETFS_RREQ_USE_IO_ITER 12 /* Use ->io_iter rather than ->i_pages */
278 #define NETFS_RREQ_ALL_QUEUED 13 /* All subreqs are now queued */
279 #define NETFS_RREQ_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark
280 * write to cache on read */
281 const struct netfs_request_ops *netfs_ops;
282 void (*cleanup)(struct netfs_io_request *req);
283 };
284
285 /*
286 * Operations the network filesystem can/must provide to the helpers.
287 */
288 struct netfs_request_ops {
289 mempool_t *request_pool;
290 mempool_t *subrequest_pool;
291 int (*init_request)(struct netfs_io_request *rreq, struct file *file);
292 void (*free_request)(struct netfs_io_request *rreq);
293 void (*free_subrequest)(struct netfs_io_subrequest *rreq);
294
295 /* Read request handling */
296 void (*expand_readahead)(struct netfs_io_request *rreq);
297 bool (*clamp_length)(struct netfs_io_subrequest *subreq);
298 void (*issue_read)(struct netfs_io_subrequest *subreq);
299 bool (*is_still_valid)(struct netfs_io_request *rreq);
300 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
301 struct folio **foliop, void **_fsdata);
302 void (*done)(struct netfs_io_request *rreq);
303
304 /* Modification handling */
305 void (*update_i_size)(struct inode *inode, loff_t i_size);
306 void (*post_modify)(struct inode *inode);
307
308 /* Write request handling */
309 void (*begin_writeback)(struct netfs_io_request *wreq);
310 void (*prepare_write)(struct netfs_io_subrequest *subreq);
311 void (*issue_write)(struct netfs_io_subrequest *subreq);
312 void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
313 void (*invalidate_cache)(struct netfs_io_request *wreq);
314 };
315
316 /*
317 * How to handle reading from a hole.
318 */
319 enum netfs_read_from_hole {
320 NETFS_READ_HOLE_IGNORE,
321 NETFS_READ_HOLE_CLEAR,
322 NETFS_READ_HOLE_FAIL,
323 };
324
325 /*
326 * Table of operations for access to a cache.
327 */
328 struct netfs_cache_ops {
329 /* End an operation */
330 void (*end_operation)(struct netfs_cache_resources *cres);
331
332 /* Read data from the cache */
333 int (*read)(struct netfs_cache_resources *cres,
334 loff_t start_pos,
335 struct iov_iter *iter,
336 enum netfs_read_from_hole read_hole,
337 netfs_io_terminated_t term_func,
338 void *term_func_priv);
339
340 /* Write data to the cache */
341 int (*write)(struct netfs_cache_resources *cres,
342 loff_t start_pos,
343 struct iov_iter *iter,
344 netfs_io_terminated_t term_func,
345 void *term_func_priv);
346
347 /* Write data to the cache from a netfs subrequest. */
348 void (*issue_write)(struct netfs_io_subrequest *subreq);
349
350 /* Expand readahead request */
351 void (*expand_readahead)(struct netfs_cache_resources *cres,
352 unsigned long long *_start,
353 unsigned long long *_len,
354 unsigned long long i_size);
355
356 /* Prepare a read operation, shortening it to a cached/uncached
357 * boundary as appropriate.
358 */
359 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
360 unsigned long long i_size);
361
362 /* Prepare a write subrequest, working out if we're allowed to do it
363 * and finding out the maximum amount of data to gather before
364 * attempting to submit. If we're not permitted to do it, the
365 * subrequest should be marked failed.
366 */
367 void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq);
368
369 /* Prepare a write operation, working out what part of the write we can
370 * actually do.
371 */
372 int (*prepare_write)(struct netfs_cache_resources *cres,
373 loff_t *_start, size_t *_len, size_t upper_len,
374 loff_t i_size, bool no_space_allocated_yet);
375
376 /* Prepare an on-demand read operation, shortening it to a cached/uncached
377 * boundary as appropriate.
378 */
379 enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
380 loff_t start, size_t *_len,
381 loff_t i_size,
382 unsigned long *_flags, ino_t ino);
383
384 /* Query the occupancy of the cache in a region, returning where the
385 * next chunk of data starts and how long it is.
386 */
387 int (*query_occupancy)(struct netfs_cache_resources *cres,
388 loff_t start, size_t len, size_t granularity,
389 loff_t *_data_start, size_t *_data_len);
390 };
391
392 /* High-level read API. */
393 ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter);
394 ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
395 ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
396 ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
397
398 /* High-level write API */
399 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
400 struct netfs_group *netfs_group);
401 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
402 struct netfs_group *netfs_group);
403 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);
404 ssize_t netfs_unbuffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *iter,
405 struct netfs_group *netfs_group);
406 ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from);
407
408 /* Address operations API */
409 struct readahead_control;
410 void netfs_readahead(struct readahead_control *);
411 int netfs_read_folio(struct file *, struct folio *);
412 int netfs_write_begin(struct netfs_inode *, struct file *,
413 struct address_space *, loff_t pos, unsigned int len,
414 struct folio **, void **fsdata);
415 int netfs_writepages(struct address_space *mapping,
416 struct writeback_control *wbc);
417 bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio);
418 int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);
419 void netfs_clear_inode_writeback(struct inode *inode, const void *aux);
420 void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
421 bool netfs_release_folio(struct folio *folio, gfp_t gfp);
422
423 /* VMA operations API. */
424 vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
425
426 /* (Sub)request management API. */
427 void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool);
428 void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
429 enum netfs_sreq_ref_trace what);
430 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
431 bool was_async, enum netfs_sreq_ref_trace what);
432 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
433 struct iov_iter *new,
434 iov_iter_extraction_t extraction_flags);
435 size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
436 size_t max_size, size_t max_segs);
437 void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq);
438 void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
439 bool was_async);
440 void netfs_queue_write_request(struct netfs_io_subrequest *subreq);
441
442 int netfs_start_io_read(struct inode *inode);
443 void netfs_end_io_read(struct inode *inode);
444 int netfs_start_io_write(struct inode *inode);
445 void netfs_end_io_write(struct inode *inode);
446 int netfs_start_io_direct(struct inode *inode);
447 void netfs_end_io_direct(struct inode *inode);
448
449 /**
450 * netfs_inode - Get the netfs inode context from the inode
451 * @inode: The inode to query
452 *
453 * Get the netfs lib inode context from the network filesystem's inode. The
454 * context struct is expected to directly follow on from the VFS inode struct.
455 */
456 static inline struct netfs_inode *netfs_inode(struct inode *inode)
457 {
458 return container_of(inode, struct netfs_inode, inode);
459 }
460
461 /**
462 * netfs_inode_init - Initialise a netfslib inode context
463 * @ctx: The netfs inode to initialise
464 * @ops: The netfs's operations list
465 * @use_zero_point: True to use the zero_point read optimisation
466 *
467 * Initialise the netfs library context struct. This is expected to follow on
468 * directly from the VFS inode struct.
469 */
470 static inline void netfs_inode_init(struct netfs_inode *ctx,
471 const struct netfs_request_ops *ops,
472 bool use_zero_point)
473 {
474 ctx->ops = ops;
475 ctx->remote_i_size = i_size_read(&ctx->inode);
476 ctx->zero_point = LLONG_MAX;
477 ctx->flags = 0;
478 atomic_set(&ctx->io_count, 0);
479 #if IS_ENABLED(CONFIG_FSCACHE)
480 ctx->cache = NULL;
481 #endif
482 mutex_init(&ctx->wb_lock);
483 /* ->releasepage() drives zero_point */
484 if (use_zero_point) {
485 ctx->zero_point = ctx->remote_i_size;
486 mapping_set_release_always(ctx->inode.i_mapping);
487 }
488 }
489
490 /**
491 * netfs_resize_file - Note that a file got resized
492 * @ctx: The netfs inode being resized
493 * @new_i_size: The new file size
494 * @changed_on_server: The change was applied to the server
495 *
496 * Inform the netfs lib that a file got resized so that it can adjust its state.
497 */
498 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size,
499 bool changed_on_server)
500 {
501 if (changed_on_server)
502 ctx->remote_i_size = new_i_size;
503 if (new_i_size < ctx->zero_point)
504 ctx->zero_point = new_i_size;
505 }
506
507 /**
508 * netfs_i_cookie - Get the cache cookie from the inode
509 * @ctx: The netfs inode to query
510 *
511 * Get the caching cookie (if enabled) from the network filesystem's inode.
512 */
513 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
514 {
515 #if IS_ENABLED(CONFIG_FSCACHE)
516 return ctx->cache;
517 #else
518 return NULL;
519 #endif
520 }
521
522 /**
523 * netfs_wait_for_outstanding_io - Wait for outstanding I/O to complete
524 * @inode: The netfs inode to wait on
525 *
526 * Wait for outstanding I/O requests of any type to complete. This is intended
527 * to be called from inode eviction routines. This makes sure that any
528 * resources held by those requests are cleaned up before we let the inode get
529 * cleaned up.
530 */
531 static inline void netfs_wait_for_outstanding_io(struct inode *inode)
532 {
533 struct netfs_inode *ictx = netfs_inode(inode);
534
535 wait_var_event(&ictx->io_count, atomic_read(&ictx->io_count) == 0);
536 }
537
538 #endif /* _LINUX_NETFS_H */
539
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