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80f94f29 DH |
1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* Manage high-level VFS aspects of a cache. | |
3 | * | |
4 | * Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
6 | */ | |
7 | ||
8 | #include <linux/slab.h> | |
9 | #include <linux/statfs.h> | |
10 | #include <linux/namei.h> | |
11 | #include "internal.h" | |
12 | ||
d1065b0a DH |
13 | /* |
14 | * Bring a cache online. | |
15 | */ | |
16 | int cachefiles_add_cache(struct cachefiles_cache *cache) | |
17 | { | |
18 | struct fscache_cache *cache_cookie; | |
19 | struct path path; | |
20 | struct kstatfs stats; | |
21 | struct dentry *graveyard, *cachedir, *root; | |
22 | const struct cred *saved_cred; | |
23 | int ret; | |
24 | ||
25 | _enter(""); | |
26 | ||
27 | cache_cookie = fscache_acquire_cache(cache->tag); | |
28 | if (IS_ERR(cache_cookie)) | |
29 | return PTR_ERR(cache_cookie); | |
30 | ||
31 | /* we want to work under the module's security ID */ | |
32 | ret = cachefiles_get_security_ID(cache); | |
33 | if (ret < 0) | |
34 | goto error_getsec; | |
35 | ||
36 | cachefiles_begin_secure(cache, &saved_cred); | |
37 | ||
38 | /* look up the directory at the root of the cache */ | |
39 | ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path); | |
40 | if (ret < 0) | |
41 | goto error_open_root; | |
42 | ||
43 | cache->mnt = path.mnt; | |
44 | root = path.dentry; | |
45 | ||
46 | ret = -EINVAL; | |
8834147f | 47 | if (is_idmapped_mnt(path.mnt)) { |
d1065b0a DH |
48 | pr_warn("File cache on idmapped mounts not supported"); |
49 | goto error_unsupported; | |
50 | } | |
51 | ||
14b9d090 DH |
52 | /* Check features of the backing filesystem: |
53 | * - Directories must support looking up and directory creation | |
66332131 | 54 | * - We create tmpfiles to handle invalidation |
14b9d090 DH |
55 | * - We use xattrs to store metadata |
56 | * - We need to be able to query the amount of space available | |
57 | * - We want to be able to sync the filesystem when stopping the cache | |
58 | * - We use DIO to/from pages, so the blocksize mustn't be too big. | |
59 | */ | |
d1065b0a DH |
60 | ret = -EOPNOTSUPP; |
61 | if (d_is_negative(root) || | |
62 | !d_backing_inode(root)->i_op->lookup || | |
63 | !d_backing_inode(root)->i_op->mkdir || | |
66332131 | 64 | !d_backing_inode(root)->i_op->tmpfile || |
d1065b0a DH |
65 | !(d_backing_inode(root)->i_opflags & IOP_XATTR) || |
66 | !root->d_sb->s_op->statfs || | |
67 | !root->d_sb->s_op->sync_fs || | |
68 | root->d_sb->s_blocksize > PAGE_SIZE) | |
69 | goto error_unsupported; | |
70 | ||
71 | ret = -EROFS; | |
72 | if (sb_rdonly(root->d_sb)) | |
73 | goto error_unsupported; | |
74 | ||
75 | /* determine the security of the on-disk cache as this governs | |
76 | * security ID of files we create */ | |
77 | ret = cachefiles_determine_cache_security(cache, root, &saved_cred); | |
78 | if (ret < 0) | |
79 | goto error_unsupported; | |
80 | ||
81 | /* get the cache size and blocksize */ | |
82 | ret = vfs_statfs(&path, &stats); | |
83 | if (ret < 0) | |
84 | goto error_unsupported; | |
85 | ||
86 | ret = -ERANGE; | |
87 | if (stats.f_bsize <= 0) | |
88 | goto error_unsupported; | |
89 | ||
90 | ret = -EOPNOTSUPP; | |
91 | if (stats.f_bsize > PAGE_SIZE) | |
92 | goto error_unsupported; | |
93 | ||
94 | cache->bsize = stats.f_bsize; | |
5638b067 | 95 | cache->bshift = ilog2(stats.f_bsize); |
d1065b0a DH |
96 | |
97 | _debug("blksize %u (shift %u)", | |
98 | cache->bsize, cache->bshift); | |
99 | ||
100 | _debug("size %llu, avail %llu", | |
101 | (unsigned long long) stats.f_blocks, | |
102 | (unsigned long long) stats.f_bavail); | |
103 | ||
104 | /* set up caching limits */ | |
105 | do_div(stats.f_files, 100); | |
106 | cache->fstop = stats.f_files * cache->fstop_percent; | |
107 | cache->fcull = stats.f_files * cache->fcull_percent; | |
108 | cache->frun = stats.f_files * cache->frun_percent; | |
109 | ||
110 | _debug("limits {%llu,%llu,%llu} files", | |
111 | (unsigned long long) cache->frun, | |
112 | (unsigned long long) cache->fcull, | |
113 | (unsigned long long) cache->fstop); | |
114 | ||
d1065b0a DH |
115 | do_div(stats.f_blocks, 100); |
116 | cache->bstop = stats.f_blocks * cache->bstop_percent; | |
117 | cache->bcull = stats.f_blocks * cache->bcull_percent; | |
118 | cache->brun = stats.f_blocks * cache->brun_percent; | |
119 | ||
120 | _debug("limits {%llu,%llu,%llu} blocks", | |
121 | (unsigned long long) cache->brun, | |
122 | (unsigned long long) cache->bcull, | |
123 | (unsigned long long) cache->bstop); | |
124 | ||
125 | /* get the cache directory and check its type */ | |
126 | cachedir = cachefiles_get_directory(cache, root, "cache", NULL); | |
127 | if (IS_ERR(cachedir)) { | |
128 | ret = PTR_ERR(cachedir); | |
129 | goto error_unsupported; | |
130 | } | |
131 | ||
132 | cache->store = cachedir; | |
133 | ||
134 | /* get the graveyard directory */ | |
135 | graveyard = cachefiles_get_directory(cache, root, "graveyard", NULL); | |
136 | if (IS_ERR(graveyard)) { | |
137 | ret = PTR_ERR(graveyard); | |
138 | goto error_unsupported; | |
139 | } | |
140 | ||
141 | cache->graveyard = graveyard; | |
142 | cache->cache = cache_cookie; | |
143 | ||
144 | ret = fscache_add_cache(cache_cookie, &cachefiles_cache_ops, cache); | |
145 | if (ret < 0) | |
146 | goto error_add_cache; | |
147 | ||
148 | /* done */ | |
149 | set_bit(CACHEFILES_READY, &cache->flags); | |
150 | dput(root); | |
151 | ||
152 | pr_info("File cache on %s registered\n", cache_cookie->name); | |
153 | ||
154 | /* check how much space the cache has */ | |
3929eca7 | 155 | cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check); |
d1065b0a DH |
156 | cachefiles_end_secure(cache, saved_cred); |
157 | _leave(" = 0 [%px]", cache->cache); | |
158 | return 0; | |
159 | ||
160 | error_add_cache: | |
161 | cachefiles_put_directory(cache->graveyard); | |
162 | cache->graveyard = NULL; | |
163 | error_unsupported: | |
164 | cachefiles_put_directory(cache->store); | |
165 | cache->store = NULL; | |
166 | mntput(cache->mnt); | |
167 | cache->mnt = NULL; | |
168 | dput(root); | |
169 | error_open_root: | |
170 | cachefiles_end_secure(cache, saved_cred); | |
171 | error_getsec: | |
172 | fscache_relinquish_cache(cache_cookie); | |
173 | cache->cache = NULL; | |
174 | pr_err("Failed to register: %d\n", ret); | |
175 | return ret; | |
176 | } | |
177 | ||
80f94f29 DH |
178 | /* |
179 | * See if we have space for a number of pages and/or a number of files in the | |
180 | * cache | |
181 | */ | |
182 | int cachefiles_has_space(struct cachefiles_cache *cache, | |
3929eca7 DH |
183 | unsigned fnr, unsigned bnr, |
184 | enum cachefiles_has_space_for reason) | |
80f94f29 DH |
185 | { |
186 | struct kstatfs stats; | |
187 | u64 b_avail, b_writing; | |
188 | int ret; | |
189 | ||
190 | struct path path = { | |
191 | .mnt = cache->mnt, | |
192 | .dentry = cache->mnt->mnt_root, | |
193 | }; | |
194 | ||
195 | //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u", | |
196 | // (unsigned long long) cache->frun, | |
197 | // (unsigned long long) cache->fcull, | |
198 | // (unsigned long long) cache->fstop, | |
199 | // (unsigned long long) cache->brun, | |
200 | // (unsigned long long) cache->bcull, | |
201 | // (unsigned long long) cache->bstop, | |
202 | // fnr, bnr); | |
203 | ||
204 | /* find out how many pages of blockdev are available */ | |
205 | memset(&stats, 0, sizeof(stats)); | |
206 | ||
207 | ret = vfs_statfs(&path, &stats); | |
208 | if (ret < 0) { | |
209 | trace_cachefiles_vfs_error(NULL, d_inode(path.dentry), ret, | |
210 | cachefiles_trace_statfs_error); | |
211 | if (ret == -EIO) | |
212 | cachefiles_io_error(cache, "statfs failed"); | |
213 | _leave(" = %d", ret); | |
214 | return ret; | |
215 | } | |
216 | ||
5638b067 | 217 | b_avail = stats.f_bavail; |
80f94f29 DH |
218 | b_writing = atomic_long_read(&cache->b_writing); |
219 | if (b_avail > b_writing) | |
220 | b_avail -= b_writing; | |
221 | else | |
222 | b_avail = 0; | |
223 | ||
224 | //_debug("avail %llu,%llu", | |
225 | // (unsigned long long)stats.f_ffree, | |
226 | // (unsigned long long)b_avail); | |
227 | ||
228 | /* see if there is sufficient space */ | |
229 | if (stats.f_ffree > fnr) | |
230 | stats.f_ffree -= fnr; | |
231 | else | |
232 | stats.f_ffree = 0; | |
233 | ||
234 | if (b_avail > bnr) | |
235 | b_avail -= bnr; | |
236 | else | |
237 | b_avail = 0; | |
238 | ||
239 | ret = -ENOBUFS; | |
240 | if (stats.f_ffree < cache->fstop || | |
241 | b_avail < cache->bstop) | |
3929eca7 | 242 | goto stop_and_begin_cull; |
80f94f29 DH |
243 | |
244 | ret = 0; | |
245 | if (stats.f_ffree < cache->fcull || | |
246 | b_avail < cache->bcull) | |
247 | goto begin_cull; | |
248 | ||
249 | if (test_bit(CACHEFILES_CULLING, &cache->flags) && | |
250 | stats.f_ffree >= cache->frun && | |
251 | b_avail >= cache->brun && | |
252 | test_and_clear_bit(CACHEFILES_CULLING, &cache->flags) | |
253 | ) { | |
254 | _debug("cease culling"); | |
255 | cachefiles_state_changed(cache); | |
256 | } | |
257 | ||
258 | //_leave(" = 0"); | |
259 | return 0; | |
260 | ||
3929eca7 DH |
261 | stop_and_begin_cull: |
262 | switch (reason) { | |
263 | case cachefiles_has_space_for_write: | |
264 | fscache_count_no_write_space(); | |
265 | break; | |
266 | case cachefiles_has_space_for_create: | |
267 | fscache_count_no_create_space(); | |
268 | break; | |
269 | default: | |
270 | break; | |
271 | } | |
80f94f29 DH |
272 | begin_cull: |
273 | if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) { | |
274 | _debug("### CULL CACHE ###"); | |
275 | cachefiles_state_changed(cache); | |
276 | } | |
277 | ||
278 | _leave(" = %d", ret); | |
279 | return ret; | |
280 | } | |
d1065b0a | 281 | |
1f08c925 DH |
282 | /* |
283 | * Mark all the objects as being out of service and queue them all for cleanup. | |
284 | */ | |
285 | static void cachefiles_withdraw_objects(struct cachefiles_cache *cache) | |
286 | { | |
287 | struct cachefiles_object *object; | |
288 | unsigned int count = 0; | |
289 | ||
290 | _enter(""); | |
291 | ||
292 | spin_lock(&cache->object_list_lock); | |
293 | ||
294 | while (!list_empty(&cache->object_list)) { | |
295 | object = list_first_entry(&cache->object_list, | |
296 | struct cachefiles_object, cache_link); | |
297 | cachefiles_see_object(object, cachefiles_obj_see_withdrawal); | |
298 | list_del_init(&object->cache_link); | |
299 | fscache_withdraw_cookie(object->cookie); | |
300 | count++; | |
301 | if ((count & 63) == 0) { | |
302 | spin_unlock(&cache->object_list_lock); | |
303 | cond_resched(); | |
304 | spin_lock(&cache->object_list_lock); | |
305 | } | |
306 | } | |
307 | ||
308 | spin_unlock(&cache->object_list_lock); | |
309 | _leave(" [%u objs]", count); | |
310 | } | |
311 | ||
fe2140e2 DH |
312 | /* |
313 | * Withdraw volumes. | |
314 | */ | |
315 | static void cachefiles_withdraw_volumes(struct cachefiles_cache *cache) | |
316 | { | |
317 | _enter(""); | |
318 | ||
319 | for (;;) { | |
320 | struct cachefiles_volume *volume = NULL; | |
321 | ||
322 | spin_lock(&cache->object_list_lock); | |
323 | if (!list_empty(&cache->volumes)) { | |
324 | volume = list_first_entry(&cache->volumes, | |
325 | struct cachefiles_volume, cache_link); | |
326 | list_del_init(&volume->cache_link); | |
327 | } | |
328 | spin_unlock(&cache->object_list_lock); | |
329 | if (!volume) | |
330 | break; | |
331 | ||
332 | cachefiles_withdraw_volume(volume); | |
333 | } | |
334 | ||
335 | _leave(""); | |
336 | } | |
337 | ||
d1065b0a DH |
338 | /* |
339 | * Sync a cache to backing disk. | |
340 | */ | |
341 | static void cachefiles_sync_cache(struct cachefiles_cache *cache) | |
342 | { | |
343 | const struct cred *saved_cred; | |
344 | int ret; | |
345 | ||
346 | _enter("%s", cache->cache->name); | |
347 | ||
348 | /* make sure all pages pinned by operations on behalf of the netfs are | |
349 | * written to disc */ | |
350 | cachefiles_begin_secure(cache, &saved_cred); | |
351 | down_read(&cache->mnt->mnt_sb->s_umount); | |
352 | ret = sync_filesystem(cache->mnt->mnt_sb); | |
353 | up_read(&cache->mnt->mnt_sb->s_umount); | |
354 | cachefiles_end_secure(cache, saved_cred); | |
355 | ||
356 | if (ret == -EIO) | |
357 | cachefiles_io_error(cache, | |
358 | "Attempt to sync backing fs superblock returned error %d", | |
359 | ret); | |
360 | } | |
361 | ||
362 | /* | |
363 | * Withdraw cache objects. | |
364 | */ | |
365 | void cachefiles_withdraw_cache(struct cachefiles_cache *cache) | |
366 | { | |
367 | struct fscache_cache *fscache = cache->cache; | |
368 | ||
369 | pr_info("File cache on %s unregistering\n", fscache->name); | |
370 | ||
371 | fscache_withdraw_cache(fscache); | |
372 | ||
373 | /* we now have to destroy all the active objects pertaining to this | |
374 | * cache - which we do by passing them off to thread pool to be | |
375 | * disposed of */ | |
1f08c925 | 376 | cachefiles_withdraw_objects(cache); |
d1065b0a DH |
377 | fscache_wait_for_objects(fscache); |
378 | ||
fe2140e2 | 379 | cachefiles_withdraw_volumes(cache); |
d1065b0a DH |
380 | cachefiles_sync_cache(cache); |
381 | cache->cache = NULL; | |
382 | fscache_relinquish_cache(fscache); | |
383 | } |