Linux kernel mirror (for testing)
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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * V9FS cache definitions.
4 *
5 * Copyright (C) 2009 by Abhishek Kulkarni <adkulkar@umail.iu.edu>
6 */
7
8#include <linux/jiffies.h>
9#include <linux/file.h>
10#include <linux/slab.h>
11#include <linux/stat.h>
12#include <linux/sched.h>
13#include <linux/fs.h>
14#include <net/9p/9p.h>
15
16#include "v9fs.h"
17#include "cache.h"
18
19#define CACHETAG_LEN 11
20
21struct fscache_netfs v9fs_cache_netfs = {
22 .name = "9p",
23 .version = 0,
24};
25
26/*
27 * v9fs_random_cachetag - Generate a random tag to be associated
28 * with a new cache session.
29 *
30 * The value of jiffies is used for a fairly randomly cache tag.
31 */
32
33static
34int v9fs_random_cachetag(struct v9fs_session_info *v9ses)
35{
36 v9ses->cachetag = kmalloc(CACHETAG_LEN, GFP_KERNEL);
37 if (!v9ses->cachetag)
38 return -ENOMEM;
39
40 return scnprintf(v9ses->cachetag, CACHETAG_LEN, "%lu", jiffies);
41}
42
43const struct fscache_cookie_def v9fs_cache_session_index_def = {
44 .name = "9P.session",
45 .type = FSCACHE_COOKIE_TYPE_INDEX,
46};
47
48void v9fs_cache_session_get_cookie(struct v9fs_session_info *v9ses)
49{
50 /* If no cache session tag was specified, we generate a random one. */
51 if (!v9ses->cachetag) {
52 if (v9fs_random_cachetag(v9ses) < 0) {
53 v9ses->fscache = NULL;
54 kfree(v9ses->cachetag);
55 v9ses->cachetag = NULL;
56 return;
57 }
58 }
59
60 v9ses->fscache = fscache_acquire_cookie(v9fs_cache_netfs.primary_index,
61 &v9fs_cache_session_index_def,
62 v9ses->cachetag,
63 strlen(v9ses->cachetag),
64 NULL, 0,
65 v9ses, 0, true);
66 p9_debug(P9_DEBUG_FSC, "session %p get cookie %p\n",
67 v9ses, v9ses->fscache);
68}
69
70void v9fs_cache_session_put_cookie(struct v9fs_session_info *v9ses)
71{
72 p9_debug(P9_DEBUG_FSC, "session %p put cookie %p\n",
73 v9ses, v9ses->fscache);
74 fscache_relinquish_cookie(v9ses->fscache, NULL, false);
75 v9ses->fscache = NULL;
76}
77
78static enum
79fscache_checkaux v9fs_cache_inode_check_aux(void *cookie_netfs_data,
80 const void *buffer,
81 uint16_t buflen,
82 loff_t object_size)
83{
84 const struct v9fs_inode *v9inode = cookie_netfs_data;
85
86 if (buflen != sizeof(v9inode->qid.version))
87 return FSCACHE_CHECKAUX_OBSOLETE;
88
89 if (memcmp(buffer, &v9inode->qid.version,
90 sizeof(v9inode->qid.version)))
91 return FSCACHE_CHECKAUX_OBSOLETE;
92
93 return FSCACHE_CHECKAUX_OKAY;
94}
95
96const struct fscache_cookie_def v9fs_cache_inode_index_def = {
97 .name = "9p.inode",
98 .type = FSCACHE_COOKIE_TYPE_DATAFILE,
99 .check_aux = v9fs_cache_inode_check_aux,
100};
101
102void v9fs_cache_inode_get_cookie(struct inode *inode)
103{
104 struct v9fs_inode *v9inode;
105 struct v9fs_session_info *v9ses;
106
107 if (!S_ISREG(inode->i_mode))
108 return;
109
110 v9inode = V9FS_I(inode);
111 if (v9inode->fscache)
112 return;
113
114 v9ses = v9fs_inode2v9ses(inode);
115 v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
116 &v9fs_cache_inode_index_def,
117 &v9inode->qid.path,
118 sizeof(v9inode->qid.path),
119 &v9inode->qid.version,
120 sizeof(v9inode->qid.version),
121 v9inode,
122 i_size_read(&v9inode->vfs_inode),
123 true);
124
125 p9_debug(P9_DEBUG_FSC, "inode %p get cookie %p\n",
126 inode, v9inode->fscache);
127}
128
129void v9fs_cache_inode_put_cookie(struct inode *inode)
130{
131 struct v9fs_inode *v9inode = V9FS_I(inode);
132
133 if (!v9inode->fscache)
134 return;
135 p9_debug(P9_DEBUG_FSC, "inode %p put cookie %p\n",
136 inode, v9inode->fscache);
137
138 fscache_relinquish_cookie(v9inode->fscache, &v9inode->qid.version,
139 false);
140 v9inode->fscache = NULL;
141}
142
143void v9fs_cache_inode_flush_cookie(struct inode *inode)
144{
145 struct v9fs_inode *v9inode = V9FS_I(inode);
146
147 if (!v9inode->fscache)
148 return;
149 p9_debug(P9_DEBUG_FSC, "inode %p flush cookie %p\n",
150 inode, v9inode->fscache);
151
152 fscache_relinquish_cookie(v9inode->fscache, NULL, true);
153 v9inode->fscache = NULL;
154}
155
156void v9fs_cache_inode_set_cookie(struct inode *inode, struct file *filp)
157{
158 struct v9fs_inode *v9inode = V9FS_I(inode);
159
160 if (!v9inode->fscache)
161 return;
162
163 mutex_lock(&v9inode->fscache_lock);
164
165 if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
166 v9fs_cache_inode_flush_cookie(inode);
167 else
168 v9fs_cache_inode_get_cookie(inode);
169
170 mutex_unlock(&v9inode->fscache_lock);
171}
172
173void v9fs_cache_inode_reset_cookie(struct inode *inode)
174{
175 struct v9fs_inode *v9inode = V9FS_I(inode);
176 struct v9fs_session_info *v9ses;
177 struct fscache_cookie *old;
178
179 if (!v9inode->fscache)
180 return;
181
182 old = v9inode->fscache;
183
184 mutex_lock(&v9inode->fscache_lock);
185 fscache_relinquish_cookie(v9inode->fscache, NULL, true);
186
187 v9ses = v9fs_inode2v9ses(inode);
188 v9inode->fscache = fscache_acquire_cookie(v9ses->fscache,
189 &v9fs_cache_inode_index_def,
190 &v9inode->qid.path,
191 sizeof(v9inode->qid.path),
192 &v9inode->qid.version,
193 sizeof(v9inode->qid.version),
194 v9inode,
195 i_size_read(&v9inode->vfs_inode),
196 true);
197 p9_debug(P9_DEBUG_FSC, "inode %p revalidating cookie old %p new %p\n",
198 inode, old, v9inode->fscache);
199
200 mutex_unlock(&v9inode->fscache_lock);
201}