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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 | ||
3d3c9504 DH |
17 | #include <linux/workqueue.h> |
18 | #include <linux/fs.h> | |
b533a83f DH |
19 | #include <linux/pagemap.h> |
20 | ||
21 | /* | |
22 | * Overload PG_private_2 to give us PG_fscache - this is used to indicate that | |
23 | * a page is currently backed by a local disk cache | |
24 | */ | |
25 | #define PageFsCache(page) PagePrivate2((page)) | |
26 | #define SetPageFsCache(page) SetPagePrivate2((page)) | |
27 | #define ClearPageFsCache(page) ClearPagePrivate2((page)) | |
28 | #define TestSetPageFsCache(page) TestSetPagePrivate2((page)) | |
29 | #define TestClearPageFsCache(page) TestClearPagePrivate2((page)) | |
30 | ||
99bff93c DH |
31 | /** |
32 | * set_page_fscache - Set PG_fscache on a page and take a ref | |
33 | * @page: The page. | |
34 | * | |
35 | * Set the PG_fscache (PG_private_2) flag on a page and take the reference | |
36 | * needed for the VM to handle its lifetime correctly. This sets the flag and | |
37 | * takes the reference unconditionally, so care must be taken not to set the | |
38 | * flag again if it's already set. | |
39 | */ | |
40 | static inline void set_page_fscache(struct page *page) | |
41 | { | |
42 | set_page_private_2(page); | |
43 | } | |
44 | ||
45 | /** | |
46 | * end_page_fscache - Clear PG_fscache and release any waiters | |
47 | * @page: The page | |
48 | * | |
49 | * Clear the PG_fscache (PG_private_2) bit on a page and wake up any sleepers | |
50 | * waiting for this. The page ref held for PG_private_2 being set is released. | |
51 | * | |
52 | * This is, for example, used when a netfs page is being written to a local | |
53 | * disk cache, thereby allowing writes to the cache for the same page to be | |
54 | * serialised. | |
55 | */ | |
56 | static inline void end_page_fscache(struct page *page) | |
57 | { | |
58 | end_page_private_2(page); | |
59 | } | |
60 | ||
61 | /** | |
62 | * wait_on_page_fscache - Wait for PG_fscache to be cleared on a page | |
63 | * @page: The page to wait on | |
64 | * | |
65 | * Wait for PG_fscache (aka PG_private_2) to be cleared on a page. | |
66 | */ | |
67 | static inline void wait_on_page_fscache(struct page *page) | |
68 | { | |
69 | wait_on_page_private_2(page); | |
70 | } | |
71 | ||
72 | /** | |
73 | * wait_on_page_fscache_killable - Wait for PG_fscache to be cleared on a page | |
74 | * @page: The page to wait on | |
75 | * | |
76 | * Wait for PG_fscache (aka PG_private_2) to be cleared on a page or until a | |
77 | * fatal signal is received by the calling task. | |
78 | * | |
79 | * Return: | |
80 | * - 0 if successful. | |
81 | * - -EINTR if a fatal signal was encountered. | |
82 | */ | |
83 | static inline int wait_on_page_fscache_killable(struct page *page) | |
84 | { | |
85 | return wait_on_page_private_2_killable(page); | |
86 | } | |
87 | ||
3d3c9504 DH |
88 | enum netfs_read_source { |
89 | NETFS_FILL_WITH_ZEROES, | |
90 | NETFS_DOWNLOAD_FROM_SERVER, | |
91 | NETFS_READ_FROM_CACHE, | |
92 | NETFS_INVALID_READ, | |
93 | } __mode(byte); | |
94 | ||
726218fd DH |
95 | typedef void (*netfs_io_terminated_t)(void *priv, ssize_t transferred_or_error, |
96 | bool was_async); | |
97 | ||
98 | /* | |
99 | * Resources required to do operations on a cache. | |
100 | */ | |
101 | struct netfs_cache_resources { | |
102 | const struct netfs_cache_ops *ops; | |
103 | void *cache_priv; | |
104 | void *cache_priv2; | |
105 | }; | |
106 | ||
3d3c9504 DH |
107 | /* |
108 | * Descriptor for a single component subrequest. | |
109 | */ | |
110 | struct netfs_read_subrequest { | |
111 | struct netfs_read_request *rreq; /* Supervising read request */ | |
112 | struct list_head rreq_link; /* Link in rreq->subrequests */ | |
113 | loff_t start; /* Where to start the I/O */ | |
114 | size_t len; /* Size of the I/O */ | |
115 | size_t transferred; /* Amount of data transferred */ | |
116 | refcount_t usage; | |
117 | short error; /* 0 or error that occurred */ | |
118 | unsigned short debug_index; /* Index in list (for debugging output) */ | |
119 | enum netfs_read_source source; /* Where to read from */ | |
120 | unsigned long flags; | |
121 | #define NETFS_SREQ_WRITE_TO_CACHE 0 /* Set if should write to cache */ | |
122 | #define NETFS_SREQ_CLEAR_TAIL 1 /* Set if the rest of the read should be cleared */ | |
123 | #define NETFS_SREQ_SHORT_READ 2 /* Set if there was a short read from the cache */ | |
124 | #define NETFS_SREQ_SEEK_DATA_READ 3 /* Set if ->read() should SEEK_DATA first */ | |
125 | #define NETFS_SREQ_NO_PROGRESS 4 /* Set if we didn't manage to read any data */ | |
126 | }; | |
127 | ||
128 | /* | |
129 | * Descriptor for a read helper request. This is used to make multiple I/O | |
130 | * requests on a variety of sources and then stitch the result together. | |
131 | */ | |
132 | struct netfs_read_request { | |
133 | struct work_struct work; | |
134 | struct inode *inode; /* The file being accessed */ | |
135 | struct address_space *mapping; /* The mapping being accessed */ | |
726218fd | 136 | struct netfs_cache_resources cache_resources; |
3d3c9504 DH |
137 | struct list_head subrequests; /* Requests to fetch I/O from disk or net */ |
138 | void *netfs_priv; /* Private data for the netfs */ | |
139 | unsigned int debug_id; | |
77b4d2c6 | 140 | unsigned int cookie_debug_id; |
3d3c9504 | 141 | atomic_t nr_rd_ops; /* Number of read ops in progress */ |
726218fd | 142 | atomic_t nr_wr_ops; /* Number of write ops in progress */ |
3d3c9504 DH |
143 | size_t submitted; /* Amount submitted for I/O so far */ |
144 | size_t len; /* Length of the request */ | |
145 | short error; /* 0 or error that occurred */ | |
146 | loff_t i_size; /* Size of the file */ | |
147 | loff_t start; /* Start position */ | |
148 | pgoff_t no_unlock_page; /* Don't unlock this page after read */ | |
149 | refcount_t usage; | |
150 | unsigned long flags; | |
151 | #define NETFS_RREQ_INCOMPLETE_IO 0 /* Some ioreqs terminated short or with error */ | |
152 | #define NETFS_RREQ_WRITE_TO_CACHE 1 /* Need to write to the cache */ | |
153 | #define NETFS_RREQ_NO_UNLOCK_PAGE 2 /* Don't unlock no_unlock_page on completion */ | |
154 | #define NETFS_RREQ_DONT_UNLOCK_PAGES 3 /* Don't unlock the pages on completion */ | |
155 | #define NETFS_RREQ_FAILED 4 /* The request failed */ | |
156 | #define NETFS_RREQ_IN_PROGRESS 5 /* Unlocked when the request completes */ | |
157 | const struct netfs_read_request_ops *netfs_ops; | |
158 | }; | |
159 | ||
160 | /* | |
161 | * Operations the network filesystem can/must provide to the helpers. | |
162 | */ | |
163 | struct netfs_read_request_ops { | |
e1b1240c | 164 | bool (*is_cache_enabled)(struct inode *inode); |
3d3c9504 | 165 | void (*init_rreq)(struct netfs_read_request *rreq, struct file *file); |
726218fd | 166 | int (*begin_cache_operation)(struct netfs_read_request *rreq); |
3d3c9504 DH |
167 | void (*expand_readahead)(struct netfs_read_request *rreq); |
168 | bool (*clamp_length)(struct netfs_read_subrequest *subreq); | |
169 | void (*issue_op)(struct netfs_read_subrequest *subreq); | |
170 | bool (*is_still_valid)(struct netfs_read_request *rreq); | |
e1b1240c DH |
171 | int (*check_write_begin)(struct file *file, loff_t pos, unsigned len, |
172 | struct page *page, void **_fsdata); | |
3d3c9504 DH |
173 | void (*done)(struct netfs_read_request *rreq); |
174 | void (*cleanup)(struct address_space *mapping, void *netfs_priv); | |
175 | }; | |
176 | ||
726218fd DH |
177 | /* |
178 | * Table of operations for access to a cache. This is obtained by | |
179 | * rreq->ops->begin_cache_operation(). | |
180 | */ | |
181 | struct netfs_cache_ops { | |
182 | /* End an operation */ | |
183 | void (*end_operation)(struct netfs_cache_resources *cres); | |
184 | ||
185 | /* Read data from the cache */ | |
186 | int (*read)(struct netfs_cache_resources *cres, | |
187 | loff_t start_pos, | |
188 | struct iov_iter *iter, | |
189 | bool seek_data, | |
190 | netfs_io_terminated_t term_func, | |
191 | void *term_func_priv); | |
192 | ||
193 | /* Write data to the cache */ | |
194 | int (*write)(struct netfs_cache_resources *cres, | |
195 | loff_t start_pos, | |
196 | struct iov_iter *iter, | |
197 | netfs_io_terminated_t term_func, | |
198 | void *term_func_priv); | |
199 | ||
200 | /* Expand readahead request */ | |
201 | void (*expand_readahead)(struct netfs_cache_resources *cres, | |
202 | loff_t *_start, size_t *_len, loff_t i_size); | |
203 | ||
204 | /* Prepare a read operation, shortening it to a cached/uncached | |
205 | * boundary as appropriate. | |
206 | */ | |
207 | enum netfs_read_source (*prepare_read)(struct netfs_read_subrequest *subreq, | |
208 | loff_t i_size); | |
209 | ||
210 | /* Prepare a write operation, working out what part of the write we can | |
211 | * actually do. | |
212 | */ | |
213 | int (*prepare_write)(struct netfs_cache_resources *cres, | |
214 | loff_t *_start, size_t *_len, loff_t i_size); | |
215 | }; | |
216 | ||
3d3c9504 DH |
217 | struct readahead_control; |
218 | extern void netfs_readahead(struct readahead_control *, | |
219 | const struct netfs_read_request_ops *, | |
220 | void *); | |
221 | extern int netfs_readpage(struct file *, | |
222 | struct page *, | |
223 | const struct netfs_read_request_ops *, | |
224 | void *); | |
e1b1240c DH |
225 | extern int netfs_write_begin(struct file *, struct address_space *, |
226 | loff_t, unsigned int, unsigned int, struct page **, | |
227 | void **, | |
228 | const struct netfs_read_request_ops *, | |
229 | void *); | |
3d3c9504 DH |
230 | |
231 | extern void netfs_subreq_terminated(struct netfs_read_subrequest *, ssize_t, bool); | |
289af54c | 232 | extern void netfs_stats_show(struct seq_file *); |
3d3c9504 | 233 | |
b533a83f | 234 | #endif /* _LINUX_NETFS_H */ |