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077b1f83 DM |
1 | /* |
2 | * Cleancache frontend | |
3 | * | |
4 | * This code provides the generic "frontend" layer to call a matching | |
5 | * "backend" driver implementation of cleancache. See | |
6 | * Documentation/vm/cleancache.txt for more information. | |
7 | * | |
8 | * Copyright (C) 2009-2010 Oracle Corp. All rights reserved. | |
9 | * Author: Dan Magenheimer | |
10 | * | |
11 | * This work is licensed under the terms of the GNU GPL, version 2. | |
12 | */ | |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/fs.h> | |
16 | #include <linux/exportfs.h> | |
17 | #include <linux/mm.h> | |
417fc2ca | 18 | #include <linux/debugfs.h> |
077b1f83 DM |
19 | #include <linux/cleancache.h> |
20 | ||
21 | /* | |
22 | * This global enablement flag may be read thousands of times per second | |
3167760f | 23 | * by cleancache_get/put/invalidate even on systems where cleancache_ops |
077b1f83 DM |
24 | * is not claimed (e.g. cleancache is config'ed on but remains |
25 | * disabled), so is preferred to the slower alternative: a function | |
26 | * call that checks a non-global. | |
27 | */ | |
072611ed | 28 | int cleancache_enabled __read_mostly; |
077b1f83 DM |
29 | EXPORT_SYMBOL(cleancache_enabled); |
30 | ||
31 | /* | |
32 | * cleancache_ops is set by cleancache_ops_register to contain the pointers | |
33 | * to the cleancache "backend" implementation functions. | |
34 | */ | |
072611ed | 35 | static struct cleancache_ops cleancache_ops __read_mostly; |
077b1f83 | 36 | |
417fc2ca DM |
37 | /* |
38 | * Counters available via /sys/kernel/debug/frontswap (if debugfs is | |
39 | * properly configured. These are for information only so are not protected | |
40 | * against increment races. | |
41 | */ | |
42 | static u64 cleancache_succ_gets; | |
43 | static u64 cleancache_failed_gets; | |
44 | static u64 cleancache_puts; | |
45 | static u64 cleancache_invalidates; | |
077b1f83 DM |
46 | |
47 | /* | |
48 | * register operations for cleancache, returning previous thus allowing | |
49 | * detection of multiple backends and possible nesting | |
50 | */ | |
51 | struct cleancache_ops cleancache_register_ops(struct cleancache_ops *ops) | |
52 | { | |
53 | struct cleancache_ops old = cleancache_ops; | |
54 | ||
55 | cleancache_ops = *ops; | |
56 | cleancache_enabled = 1; | |
57 | return old; | |
58 | } | |
59 | EXPORT_SYMBOL(cleancache_register_ops); | |
60 | ||
61 | /* Called by a cleancache-enabled filesystem at time of mount */ | |
62 | void __cleancache_init_fs(struct super_block *sb) | |
63 | { | |
64 | sb->cleancache_poolid = (*cleancache_ops.init_fs)(PAGE_SIZE); | |
65 | } | |
66 | EXPORT_SYMBOL(__cleancache_init_fs); | |
67 | ||
68 | /* Called by a cleancache-enabled clustered filesystem at time of mount */ | |
69 | void __cleancache_init_shared_fs(char *uuid, struct super_block *sb) | |
70 | { | |
71 | sb->cleancache_poolid = | |
72 | (*cleancache_ops.init_shared_fs)(uuid, PAGE_SIZE); | |
73 | } | |
74 | EXPORT_SYMBOL(__cleancache_init_shared_fs); | |
75 | ||
76 | /* | |
77 | * If the filesystem uses exportable filehandles, use the filehandle as | |
78 | * the key, else use the inode number. | |
79 | */ | |
80 | static int cleancache_get_key(struct inode *inode, | |
81 | struct cleancache_filekey *key) | |
82 | { | |
83 | int (*fhfn)(struct dentry *, __u32 *fh, int *, int); | |
84 | int len = 0, maxlen = CLEANCACHE_KEY_MAX; | |
85 | struct super_block *sb = inode->i_sb; | |
86 | ||
87 | key->u.ino = inode->i_ino; | |
88 | if (sb->s_export_op != NULL) { | |
89 | fhfn = sb->s_export_op->encode_fh; | |
90 | if (fhfn) { | |
91 | struct dentry d; | |
92 | d.d_inode = inode; | |
93 | len = (*fhfn)(&d, &key->u.fh[0], &maxlen, 0); | |
94 | if (len <= 0 || len == 255) | |
95 | return -1; | |
96 | if (maxlen > CLEANCACHE_KEY_MAX) | |
97 | return -1; | |
98 | } | |
99 | } | |
100 | return 0; | |
101 | } | |
102 | ||
103 | /* | |
104 | * "Get" data from cleancache associated with the poolid/inode/index | |
105 | * that were specified when the data was put to cleanache and, if | |
106 | * successful, use it to fill the specified page with data and return 0. | |
107 | * The pageframe is unchanged and returns -1 if the get fails. | |
108 | * Page must be locked by caller. | |
109 | */ | |
110 | int __cleancache_get_page(struct page *page) | |
111 | { | |
112 | int ret = -1; | |
113 | int pool_id; | |
114 | struct cleancache_filekey key = { .u.key = { 0 } }; | |
115 | ||
116 | VM_BUG_ON(!PageLocked(page)); | |
117 | pool_id = page->mapping->host->i_sb->cleancache_poolid; | |
118 | if (pool_id < 0) | |
119 | goto out; | |
120 | ||
121 | if (cleancache_get_key(page->mapping->host, &key) < 0) | |
122 | goto out; | |
123 | ||
124 | ret = (*cleancache_ops.get_page)(pool_id, key, page->index, page); | |
125 | if (ret == 0) | |
126 | cleancache_succ_gets++; | |
127 | else | |
128 | cleancache_failed_gets++; | |
129 | out: | |
130 | return ret; | |
131 | } | |
132 | EXPORT_SYMBOL(__cleancache_get_page); | |
133 | ||
134 | /* | |
135 | * "Put" data from a page to cleancache and associate it with the | |
136 | * (previously-obtained per-filesystem) poolid and the page's, | |
137 | * inode and page index. Page must be locked. Note that a put_page | |
138 | * always "succeeds", though a subsequent get_page may succeed or fail. | |
139 | */ | |
140 | void __cleancache_put_page(struct page *page) | |
141 | { | |
142 | int pool_id; | |
143 | struct cleancache_filekey key = { .u.key = { 0 } }; | |
144 | ||
145 | VM_BUG_ON(!PageLocked(page)); | |
146 | pool_id = page->mapping->host->i_sb->cleancache_poolid; | |
147 | if (pool_id >= 0 && | |
148 | cleancache_get_key(page->mapping->host, &key) >= 0) { | |
149 | (*cleancache_ops.put_page)(pool_id, key, page->index, page); | |
150 | cleancache_puts++; | |
151 | } | |
152 | } | |
153 | EXPORT_SYMBOL(__cleancache_put_page); | |
154 | ||
155 | /* | |
3167760f | 156 | * Invalidate any data from cleancache associated with the poolid and the |
077b1f83 DM |
157 | * page's inode and page index so that a subsequent "get" will fail. |
158 | */ | |
3167760f DM |
159 | void __cleancache_invalidate_page(struct address_space *mapping, |
160 | struct page *page) | |
077b1f83 DM |
161 | { |
162 | /* careful... page->mapping is NULL sometimes when this is called */ | |
163 | int pool_id = mapping->host->i_sb->cleancache_poolid; | |
164 | struct cleancache_filekey key = { .u.key = { 0 } }; | |
165 | ||
166 | if (pool_id >= 0) { | |
167 | VM_BUG_ON(!PageLocked(page)); | |
168 | if (cleancache_get_key(mapping->host, &key) >= 0) { | |
91c6cc9b DM |
169 | (*cleancache_ops.invalidate_page)(pool_id, |
170 | key, page->index); | |
417fc2ca | 171 | cleancache_invalidates++; |
077b1f83 DM |
172 | } |
173 | } | |
174 | } | |
3167760f | 175 | EXPORT_SYMBOL(__cleancache_invalidate_page); |
077b1f83 DM |
176 | |
177 | /* | |
3167760f | 178 | * Invalidate all data from cleancache associated with the poolid and the |
077b1f83 DM |
179 | * mappings's inode so that all subsequent gets to this poolid/inode |
180 | * will fail. | |
181 | */ | |
3167760f | 182 | void __cleancache_invalidate_inode(struct address_space *mapping) |
077b1f83 DM |
183 | { |
184 | int pool_id = mapping->host->i_sb->cleancache_poolid; | |
185 | struct cleancache_filekey key = { .u.key = { 0 } }; | |
186 | ||
187 | if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0) | |
91c6cc9b | 188 | (*cleancache_ops.invalidate_inode)(pool_id, key); |
077b1f83 | 189 | } |
3167760f | 190 | EXPORT_SYMBOL(__cleancache_invalidate_inode); |
077b1f83 DM |
191 | |
192 | /* | |
193 | * Called by any cleancache-enabled filesystem at time of unmount; | |
194 | * note that pool_id is surrendered and may be reutrned by a subsequent | |
195 | * cleancache_init_fs or cleancache_init_shared_fs | |
196 | */ | |
3167760f | 197 | void __cleancache_invalidate_fs(struct super_block *sb) |
077b1f83 DM |
198 | { |
199 | if (sb->cleancache_poolid >= 0) { | |
200 | int old_poolid = sb->cleancache_poolid; | |
201 | sb->cleancache_poolid = -1; | |
91c6cc9b | 202 | (*cleancache_ops.invalidate_fs)(old_poolid); |
077b1f83 DM |
203 | } |
204 | } | |
3167760f | 205 | EXPORT_SYMBOL(__cleancache_invalidate_fs); |
077b1f83 | 206 | |
077b1f83 DM |
207 | static int __init init_cleancache(void) |
208 | { | |
417fc2ca DM |
209 | #ifdef CONFIG_DEBUG_FS |
210 | struct dentry *root = debugfs_create_dir("cleancache", NULL); | |
211 | if (root == NULL) | |
212 | return -ENXIO; | |
213 | debugfs_create_u64("succ_gets", S_IRUGO, root, &cleancache_succ_gets); | |
214 | debugfs_create_u64("failed_gets", S_IRUGO, | |
215 | root, &cleancache_failed_gets); | |
216 | debugfs_create_u64("puts", S_IRUGO, root, &cleancache_puts); | |
217 | debugfs_create_u64("invalidates", S_IRUGO, | |
218 | root, &cleancache_invalidates); | |
219 | #endif | |
077b1f83 DM |
220 | return 0; |
221 | } | |
222 | module_init(init_cleancache) |