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;
23 typedef struct mempool_s mempool_t;
26 * folio_start_private_2 - Start an fscache write on a folio. [DEPRECATED]
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.
32 * Note that this should no longer be used.
34 static inline void folio_start_private_2(struct folio *folio)
36 VM_BUG_ON_FOLIO(folio_test_private_2(folio), folio);
38 folio_set_private_2(folio);
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 */
45 enum netfs_io_source {
46 NETFS_FILL_WITH_ZEROES,
47 NETFS_DOWNLOAD_FROM_SERVER,
48 NETFS_READ_FROM_CACHE,
50 NETFS_UPLOAD_TO_SERVER,
55 typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error,
59 * Per-inode context. This wraps the VFS 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;
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
72 #define NETFS_ICTX_ODIRECT 0 /* The file has DIO in progress */
73 #define NETFS_ICTX_UNBUFFERED 1 /* I/O should not use the pagecache */
74 #define NETFS_ICTX_WRITETHROUGH 2 /* Write-through caching */
75 #define NETFS_ICTX_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark
76 * write to cache on read */
80 * A netfs group - for instance a ceph snap. This is marked on dirty pages and
81 * pages marked with a group must be flushed before they can be written under
82 * the domain of another group.
86 void (*free)(struct netfs_group *netfs_group);
90 * Information about a dirty page (attached only if necessary).
94 struct netfs_group *netfs_group; /* Filesystem's grouping marker (or NULL). */
95 unsigned int dirty_offset; /* Write-streaming dirty data offset */
96 unsigned int dirty_len; /* Write-streaming dirty data length */
98 #define NETFS_FOLIO_INFO 0x1UL /* OR'd with folio->private. */
99 #define NETFS_FOLIO_COPY_TO_CACHE ((struct netfs_group *)0x356UL) /* Write to the cache only */
101 static inline bool netfs_is_folio_info(const void *priv)
103 return (unsigned long)priv & NETFS_FOLIO_INFO;
106 static inline struct netfs_folio *__netfs_folio_info(const void *priv)
108 if (netfs_is_folio_info(priv))
109 return (struct netfs_folio *)((unsigned long)priv & ~NETFS_FOLIO_INFO);
113 static inline struct netfs_folio *netfs_folio_info(struct folio *folio)
115 return __netfs_folio_info(folio_get_private(folio));
118 static inline struct netfs_group *netfs_folio_group(struct folio *folio)
120 struct netfs_folio *finfo;
121 void *priv = folio_get_private(folio);
123 finfo = netfs_folio_info(folio);
125 return finfo->netfs_group;
130 * Stream of I/O subrequests going to a particular destination, such as the
131 * server or the local cache. This is mainly intended for writing where we may
132 * have to write to multiple destinations concurrently.
134 struct netfs_io_stream {
135 /* Submission tracking */
136 struct netfs_io_subrequest *construct; /* Op being constructed */
137 unsigned int submit_off; /* Folio offset we're submitting from */
138 unsigned int submit_len; /* Amount of data left to submit */
139 unsigned int submit_max_len; /* Amount I/O can be rounded up to */
140 void (*prepare_write)(struct netfs_io_subrequest *subreq);
141 void (*issue_write)(struct netfs_io_subrequest *subreq);
142 /* Collection tracking */
143 struct list_head subrequests; /* Contributory I/O operations */
144 struct netfs_io_subrequest *front; /* Op being collected */
145 unsigned long long collected_to; /* Position we've collected results to */
146 size_t transferred; /* The amount transferred from this stream */
147 enum netfs_io_source source; /* Where to read from/write to */
148 unsigned short error; /* Aggregate error for the stream */
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 */
157 * Resources required to do operations on a cache.
159 struct netfs_cache_resources {
160 const struct netfs_cache_ops *ops;
163 unsigned int debug_id; /* Cookie debug ID */
164 unsigned int inval_counter; /* object->inval_counter at begin_op */
168 * Descriptor for a single component subrequest. Each operation represents an
169 * individual read/write from/to a server, a cache, a journal, etc..
171 * The buffer iterator is persistent for the life of the subrequest struct and
172 * the pages it points to can be relied on to exist for the duration.
174 struct netfs_io_subrequest {
175 struct netfs_io_request *rreq; /* Supervising I/O request */
176 struct work_struct work;
177 struct list_head rreq_link; /* Link in rreq->subrequests */
178 struct iov_iter io_iter; /* Iterator for this subrequest */
179 unsigned long long start; /* Where to start the I/O */
180 size_t max_len; /* Maximum size of the I/O */
181 size_t len; /* Size of the I/O */
182 size_t transferred; /* Amount of data transferred */
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 unsigned int max_nr_segs; /* 0 or max number of segments in an iterator */
188 enum netfs_io_source source; /* Where to read from/write to */
189 unsigned char stream_nr; /* I/O stream this belongs to */
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_SHORT_IO 2 /* Set if the I/O was short */
194 #define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */
195 #define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */
196 #define NETFS_SREQ_ONDEMAND 5 /* Set if it's from on-demand read mode */
197 #define NETFS_SREQ_BOUNDARY 6 /* Set if ends on hard boundary (eg. ceph object) */
198 #define NETFS_SREQ_IN_PROGRESS 8 /* Unlocked when the subrequest completes */
199 #define NETFS_SREQ_NEED_RETRY 9 /* Set if the filesystem requests a retry */
200 #define NETFS_SREQ_RETRYING 10 /* Set if we're retrying */
201 #define NETFS_SREQ_FAILED 11 /* Set if the subreq failed unretryably */
204 enum netfs_io_origin {
205 NETFS_READAHEAD, /* This read was triggered by readahead */
206 NETFS_READPAGE, /* This read is a synchronous read */
207 NETFS_READ_FOR_WRITE, /* This read is to prepare a write */
208 NETFS_COPY_TO_CACHE, /* This write is to copy a read to the cache */
209 NETFS_WRITEBACK, /* This write was triggered by writepages */
210 NETFS_WRITETHROUGH, /* This write was made by netfs_perform_write() */
211 NETFS_UNBUFFERED_WRITE, /* This is an unbuffered write */
212 NETFS_DIO_READ, /* This is a direct I/O read */
213 NETFS_DIO_WRITE, /* This is a direct I/O write */
218 * Descriptor for an I/O helper request. This is used to make multiple I/O
219 * operations to a variety of data stores and then stitch the result together.
221 struct netfs_io_request {
223 struct work_struct work;
226 struct inode *inode; /* The file being accessed */
227 struct address_space *mapping; /* The mapping being accessed */
228 struct kiocb *iocb; /* AIO completion vector */
229 struct netfs_cache_resources cache_resources;
230 struct list_head proc_link; /* Link in netfs_iorequests */
231 struct list_head subrequests; /* Contributory I/O operations */
232 struct netfs_io_stream io_streams[2]; /* Streams of parallel I/O operations */
233 #define NR_IO_STREAMS 2 //wreq->nr_io_streams
234 struct netfs_group *group; /* Writeback group being written back */
235 struct iov_iter iter; /* Unencrypted-side iterator */
236 struct iov_iter io_iter; /* I/O (Encrypted-side) iterator */
237 void *netfs_priv; /* Private data for the netfs */
238 void *netfs_priv2; /* Private data for the netfs */
239 struct bio_vec *direct_bv; /* DIO buffer list (when handling iovec-iter) */
240 unsigned int direct_bv_count; /* Number of elements in direct_bv[] */
241 unsigned int debug_id;
242 unsigned int rsize; /* Maximum read size (0 for none) */
243 unsigned int wsize; /* Maximum write size (0 for none) */
244 atomic_t subreq_counter; /* Next subreq->debug_index */
245 unsigned int nr_group_rel; /* Number of refs to release on ->group */
246 spinlock_t lock; /* Lock for queuing subreqs */
247 atomic_t nr_outstanding; /* Number of ops in progress */
248 atomic_t nr_copy_ops; /* Number of copy-to-cache ops in progress */
249 size_t upper_len; /* Length can be extended to here */
250 unsigned long long submitted; /* Amount submitted for I/O so far */
251 unsigned long long len; /* Length of the request */
252 size_t transferred; /* Amount to be indicated as transferred */
253 short error; /* 0 or error that occurred */
254 enum netfs_io_origin origin; /* Origin of the request */
255 bool direct_bv_unpin; /* T if direct_bv[] must be unpinned */
256 unsigned long long i_size; /* Size of the file */
257 unsigned long long start; /* Start position */
258 atomic64_t issued_to; /* Write issuer folio cursor */
259 unsigned long long contiguity; /* Tracking for gaps in the writeback sequence */
260 unsigned long long collected_to; /* Point we've collected to */
261 unsigned long long cleaned_to; /* Position we've cleaned folios to */
262 pgoff_t no_unlock_folio; /* Don't unlock this folio after read */
265 #define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */
266 #define NETFS_RREQ_COPY_TO_CACHE 1 /* Need to write to the cache */
267 #define NETFS_RREQ_NO_UNLOCK_FOLIO 2 /* Don't unlock no_unlock_folio on completion */
268 #define NETFS_RREQ_DONT_UNLOCK_FOLIOS 3 /* Don't unlock the folios on completion */
269 #define NETFS_RREQ_FAILED 4 /* The request failed */
270 #define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */
271 #define NETFS_RREQ_WRITE_TO_CACHE 7 /* Need to write to the cache */
272 #define NETFS_RREQ_UPLOAD_TO_SERVER 8 /* Need to write to the server */
273 #define NETFS_RREQ_NONBLOCK 9 /* Don't block if possible (O_NONBLOCK) */
274 #define NETFS_RREQ_BLOCKED 10 /* We blocked */
275 #define NETFS_RREQ_PAUSE 11 /* Pause subrequest generation */
276 #define NETFS_RREQ_USE_IO_ITER 12 /* Use ->io_iter rather than ->i_pages */
277 #define NETFS_RREQ_ALL_QUEUED 13 /* All subreqs are now queued */
278 #define NETFS_RREQ_USE_PGPRIV2 31 /* [DEPRECATED] Use PG_private_2 to mark
279 * write to cache on read */
280 const struct netfs_request_ops *netfs_ops;
281 void (*cleanup)(struct netfs_io_request *req);
285 * Operations the network filesystem can/must provide to the helpers.
287 struct netfs_request_ops {
288 mempool_t *request_pool;
289 mempool_t *subrequest_pool;
290 int (*init_request)(struct netfs_io_request *rreq, struct file *file);
291 void (*free_request)(struct netfs_io_request *rreq);
292 void (*free_subrequest)(struct netfs_io_subrequest *rreq);
294 /* Read request handling */
295 void (*expand_readahead)(struct netfs_io_request *rreq);
296 bool (*clamp_length)(struct netfs_io_subrequest *subreq);
297 void (*issue_read)(struct netfs_io_subrequest *subreq);
298 bool (*is_still_valid)(struct netfs_io_request *rreq);
299 int (*check_write_begin)(struct file *file, loff_t pos, unsigned len,
300 struct folio **foliop, void **_fsdata);
301 void (*done)(struct netfs_io_request *rreq);
303 /* Modification handling */
304 void (*update_i_size)(struct inode *inode, loff_t i_size);
305 void (*post_modify)(struct inode *inode);
307 /* Write request handling */
308 void (*begin_writeback)(struct netfs_io_request *wreq);
309 void (*prepare_write)(struct netfs_io_subrequest *subreq);
310 void (*issue_write)(struct netfs_io_subrequest *subreq);
311 void (*retry_request)(struct netfs_io_request *wreq, struct netfs_io_stream *stream);
312 void (*invalidate_cache)(struct netfs_io_request *wreq);
316 * How to handle reading from a hole.
318 enum netfs_read_from_hole {
319 NETFS_READ_HOLE_IGNORE,
320 NETFS_READ_HOLE_CLEAR,
321 NETFS_READ_HOLE_FAIL,
325 * Table of operations for access to a cache.
327 struct netfs_cache_ops {
328 /* End an operation */
329 void (*end_operation)(struct netfs_cache_resources *cres);
331 /* Read data from the cache */
332 int (*read)(struct netfs_cache_resources *cres,
334 struct iov_iter *iter,
335 enum netfs_read_from_hole read_hole,
336 netfs_io_terminated_t term_func,
337 void *term_func_priv);
339 /* Write data to the cache */
340 int (*write)(struct netfs_cache_resources *cres,
342 struct iov_iter *iter,
343 netfs_io_terminated_t term_func,
344 void *term_func_priv);
346 /* Write data to the cache from a netfs subrequest. */
347 void (*issue_write)(struct netfs_io_subrequest *subreq);
349 /* Expand readahead request */
350 void (*expand_readahead)(struct netfs_cache_resources *cres,
351 unsigned long long *_start,
352 unsigned long long *_len,
353 unsigned long long i_size);
355 /* Prepare a read operation, shortening it to a cached/uncached
356 * boundary as appropriate.
358 enum netfs_io_source (*prepare_read)(struct netfs_io_subrequest *subreq,
359 unsigned long long i_size);
361 /* Prepare a write subrequest, working out if we're allowed to do it
362 * and finding out the maximum amount of data to gather before
363 * attempting to submit. If we're not permitted to do it, the
364 * subrequest should be marked failed.
366 void (*prepare_write_subreq)(struct netfs_io_subrequest *subreq);
368 /* Prepare a write operation, working out what part of the write we can
371 int (*prepare_write)(struct netfs_cache_resources *cres,
372 loff_t *_start, size_t *_len, size_t upper_len,
373 loff_t i_size, bool no_space_allocated_yet);
375 /* Prepare an on-demand read operation, shortening it to a cached/uncached
376 * boundary as appropriate.
378 enum netfs_io_source (*prepare_ondemand_read)(struct netfs_cache_resources *cres,
379 loff_t start, size_t *_len,
381 unsigned long *_flags, ino_t ino);
383 /* Query the occupancy of the cache in a region, returning where the
384 * next chunk of data starts and how long it is.
386 int (*query_occupancy)(struct netfs_cache_resources *cres,
387 loff_t start, size_t len, size_t granularity,
388 loff_t *_data_start, size_t *_data_len);
391 /* High-level read API. */
392 ssize_t netfs_unbuffered_read_iter_locked(struct kiocb *iocb, struct iov_iter *iter);
393 ssize_t netfs_unbuffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
394 ssize_t netfs_buffered_read_iter(struct kiocb *iocb, struct iov_iter *iter);
395 ssize_t netfs_file_read_iter(struct kiocb *iocb, struct iov_iter *iter);
397 /* High-level write API */
398 ssize_t netfs_perform_write(struct kiocb *iocb, struct iov_iter *iter,
399 struct netfs_group *netfs_group);
400 ssize_t netfs_buffered_write_iter_locked(struct kiocb *iocb, struct iov_iter *from,
401 struct netfs_group *netfs_group);
402 ssize_t netfs_unbuffered_write_iter(struct kiocb *iocb, struct iov_iter *from);
403 ssize_t netfs_file_write_iter(struct kiocb *iocb, struct iov_iter *from);
405 /* Address operations API */
406 struct readahead_control;
407 void netfs_readahead(struct readahead_control *);
408 int netfs_read_folio(struct file *, struct folio *);
409 int netfs_write_begin(struct netfs_inode *, struct file *,
410 struct address_space *, loff_t pos, unsigned int len,
411 struct folio **, void **fsdata);
412 int netfs_writepages(struct address_space *mapping,
413 struct writeback_control *wbc);
414 bool netfs_dirty_folio(struct address_space *mapping, struct folio *folio);
415 int netfs_unpin_writeback(struct inode *inode, struct writeback_control *wbc);
416 void netfs_clear_inode_writeback(struct inode *inode, const void *aux);
417 void netfs_invalidate_folio(struct folio *folio, size_t offset, size_t length);
418 bool netfs_release_folio(struct folio *folio, gfp_t gfp);
420 /* VMA operations API. */
421 vm_fault_t netfs_page_mkwrite(struct vm_fault *vmf, struct netfs_group *netfs_group);
423 /* (Sub)request management API. */
424 void netfs_subreq_terminated(struct netfs_io_subrequest *, ssize_t, bool);
425 void netfs_get_subrequest(struct netfs_io_subrequest *subreq,
426 enum netfs_sreq_ref_trace what);
427 void netfs_put_subrequest(struct netfs_io_subrequest *subreq,
428 bool was_async, enum netfs_sreq_ref_trace what);
429 ssize_t netfs_extract_user_iter(struct iov_iter *orig, size_t orig_len,
430 struct iov_iter *new,
431 iov_iter_extraction_t extraction_flags);
432 size_t netfs_limit_iter(const struct iov_iter *iter, size_t start_offset,
433 size_t max_size, size_t max_segs);
434 void netfs_prepare_write_failed(struct netfs_io_subrequest *subreq);
435 void netfs_write_subrequest_terminated(void *_op, ssize_t transferred_or_error,
437 void netfs_queue_write_request(struct netfs_io_subrequest *subreq);
439 int netfs_start_io_read(struct inode *inode);
440 void netfs_end_io_read(struct inode *inode);
441 int netfs_start_io_write(struct inode *inode);
442 void netfs_end_io_write(struct inode *inode);
443 int netfs_start_io_direct(struct inode *inode);
444 void netfs_end_io_direct(struct inode *inode);
447 * netfs_inode - Get the netfs inode context from the inode
448 * @inode: The inode to query
450 * Get the netfs lib inode context from the network filesystem's inode. The
451 * context struct is expected to directly follow on from the VFS inode struct.
453 static inline struct netfs_inode *netfs_inode(struct inode *inode)
455 return container_of(inode, struct netfs_inode, inode);
459 * netfs_inode_init - Initialise a netfslib inode context
460 * @ctx: The netfs inode to initialise
461 * @ops: The netfs's operations list
462 * @use_zero_point: True to use the zero_point read optimisation
464 * Initialise the netfs library context struct. This is expected to follow on
465 * directly from the VFS inode struct.
467 static inline void netfs_inode_init(struct netfs_inode *ctx,
468 const struct netfs_request_ops *ops,
472 ctx->remote_i_size = i_size_read(&ctx->inode);
473 ctx->zero_point = LLONG_MAX;
475 #if IS_ENABLED(CONFIG_FSCACHE)
478 mutex_init(&ctx->wb_lock);
479 /* ->releasepage() drives zero_point */
480 if (use_zero_point) {
481 ctx->zero_point = ctx->remote_i_size;
482 mapping_set_release_always(ctx->inode.i_mapping);
487 * netfs_resize_file - Note that a file got resized
488 * @ctx: The netfs inode being resized
489 * @new_i_size: The new file size
490 * @changed_on_server: The change was applied to the server
492 * Inform the netfs lib that a file got resized so that it can adjust its state.
494 static inline void netfs_resize_file(struct netfs_inode *ctx, loff_t new_i_size,
495 bool changed_on_server)
497 if (changed_on_server)
498 ctx->remote_i_size = new_i_size;
499 if (new_i_size < ctx->zero_point)
500 ctx->zero_point = new_i_size;
504 * netfs_i_cookie - Get the cache cookie from the inode
505 * @ctx: The netfs inode to query
507 * Get the caching cookie (if enabled) from the network filesystem's inode.
509 static inline struct fscache_cookie *netfs_i_cookie(struct netfs_inode *ctx)
511 #if IS_ENABLED(CONFIG_FSCACHE)
518 #endif /* _LINUX_NETFS_H */