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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> | |
522018a0 | 11 | #include <trace/events/fscache.h> |
80f94f29 DH |
12 | #include "internal.h" |
13 | ||
d1065b0a DH |
14 | /* |
15 | * Bring a cache online. | |
16 | */ | |
17 | int cachefiles_add_cache(struct cachefiles_cache *cache) | |
18 | { | |
19 | struct fscache_cache *cache_cookie; | |
20 | struct path path; | |
21 | struct kstatfs stats; | |
22 | struct dentry *graveyard, *cachedir, *root; | |
23 | const struct cred *saved_cred; | |
24 | int ret; | |
25 | ||
26 | _enter(""); | |
27 | ||
28 | cache_cookie = fscache_acquire_cache(cache->tag); | |
29 | if (IS_ERR(cache_cookie)) | |
30 | return PTR_ERR(cache_cookie); | |
31 | ||
32 | /* we want to work under the module's security ID */ | |
33 | ret = cachefiles_get_security_ID(cache); | |
34 | if (ret < 0) | |
35 | goto error_getsec; | |
36 | ||
37 | cachefiles_begin_secure(cache, &saved_cred); | |
38 | ||
39 | /* look up the directory at the root of the cache */ | |
40 | ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path); | |
41 | if (ret < 0) | |
42 | goto error_open_root; | |
43 | ||
44 | cache->mnt = path.mnt; | |
45 | root = path.dentry; | |
46 | ||
47 | ret = -EINVAL; | |
8834147f | 48 | if (is_idmapped_mnt(path.mnt)) { |
d1065b0a DH |
49 | pr_warn("File cache on idmapped mounts not supported"); |
50 | goto error_unsupported; | |
51 | } | |
52 | ||
14b9d090 DH |
53 | /* Check features of the backing filesystem: |
54 | * - Directories must support looking up and directory creation | |
66332131 | 55 | * - We create tmpfiles to handle invalidation |
14b9d090 DH |
56 | * - We use xattrs to store metadata |
57 | * - We need to be able to query the amount of space available | |
58 | * - We want to be able to sync the filesystem when stopping the cache | |
59 | * - We use DIO to/from pages, so the blocksize mustn't be too big. | |
60 | */ | |
d1065b0a DH |
61 | ret = -EOPNOTSUPP; |
62 | if (d_is_negative(root) || | |
63 | !d_backing_inode(root)->i_op->lookup || | |
64 | !d_backing_inode(root)->i_op->mkdir || | |
66332131 | 65 | !d_backing_inode(root)->i_op->tmpfile || |
d1065b0a DH |
66 | !(d_backing_inode(root)->i_opflags & IOP_XATTR) || |
67 | !root->d_sb->s_op->statfs || | |
68 | !root->d_sb->s_op->sync_fs || | |
69 | root->d_sb->s_blocksize > PAGE_SIZE) | |
70 | goto error_unsupported; | |
71 | ||
72 | ret = -EROFS; | |
73 | if (sb_rdonly(root->d_sb)) | |
74 | goto error_unsupported; | |
75 | ||
76 | /* determine the security of the on-disk cache as this governs | |
77 | * security ID of files we create */ | |
78 | ret = cachefiles_determine_cache_security(cache, root, &saved_cred); | |
79 | if (ret < 0) | |
80 | goto error_unsupported; | |
81 | ||
82 | /* get the cache size and blocksize */ | |
83 | ret = vfs_statfs(&path, &stats); | |
84 | if (ret < 0) | |
85 | goto error_unsupported; | |
86 | ||
87 | ret = -ERANGE; | |
88 | if (stats.f_bsize <= 0) | |
89 | goto error_unsupported; | |
90 | ||
91 | ret = -EOPNOTSUPP; | |
92 | if (stats.f_bsize > PAGE_SIZE) | |
93 | goto error_unsupported; | |
94 | ||
95 | cache->bsize = stats.f_bsize; | |
5638b067 | 96 | cache->bshift = ilog2(stats.f_bsize); |
d1065b0a DH |
97 | |
98 | _debug("blksize %u (shift %u)", | |
99 | cache->bsize, cache->bshift); | |
100 | ||
101 | _debug("size %llu, avail %llu", | |
102 | (unsigned long long) stats.f_blocks, | |
103 | (unsigned long long) stats.f_bavail); | |
104 | ||
105 | /* set up caching limits */ | |
106 | do_div(stats.f_files, 100); | |
107 | cache->fstop = stats.f_files * cache->fstop_percent; | |
108 | cache->fcull = stats.f_files * cache->fcull_percent; | |
109 | cache->frun = stats.f_files * cache->frun_percent; | |
110 | ||
111 | _debug("limits {%llu,%llu,%llu} files", | |
112 | (unsigned long long) cache->frun, | |
113 | (unsigned long long) cache->fcull, | |
114 | (unsigned long long) cache->fstop); | |
115 | ||
d1065b0a DH |
116 | do_div(stats.f_blocks, 100); |
117 | cache->bstop = stats.f_blocks * cache->bstop_percent; | |
118 | cache->bcull = stats.f_blocks * cache->bcull_percent; | |
119 | cache->brun = stats.f_blocks * cache->brun_percent; | |
120 | ||
121 | _debug("limits {%llu,%llu,%llu} blocks", | |
122 | (unsigned long long) cache->brun, | |
123 | (unsigned long long) cache->bcull, | |
124 | (unsigned long long) cache->bstop); | |
125 | ||
126 | /* get the cache directory and check its type */ | |
127 | cachedir = cachefiles_get_directory(cache, root, "cache", NULL); | |
128 | if (IS_ERR(cachedir)) { | |
129 | ret = PTR_ERR(cachedir); | |
130 | goto error_unsupported; | |
131 | } | |
132 | ||
133 | cache->store = cachedir; | |
134 | ||
135 | /* get the graveyard directory */ | |
136 | graveyard = cachefiles_get_directory(cache, root, "graveyard", NULL); | |
137 | if (IS_ERR(graveyard)) { | |
138 | ret = PTR_ERR(graveyard); | |
139 | goto error_unsupported; | |
140 | } | |
141 | ||
142 | cache->graveyard = graveyard; | |
143 | cache->cache = cache_cookie; | |
144 | ||
145 | ret = fscache_add_cache(cache_cookie, &cachefiles_cache_ops, cache); | |
146 | if (ret < 0) | |
147 | goto error_add_cache; | |
148 | ||
149 | /* done */ | |
150 | set_bit(CACHEFILES_READY, &cache->flags); | |
151 | dput(root); | |
152 | ||
153 | pr_info("File cache on %s registered\n", cache_cookie->name); | |
154 | ||
155 | /* check how much space the cache has */ | |
3929eca7 | 156 | cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check); |
d1065b0a DH |
157 | cachefiles_end_secure(cache, saved_cred); |
158 | _leave(" = 0 [%px]", cache->cache); | |
159 | return 0; | |
160 | ||
161 | error_add_cache: | |
162 | cachefiles_put_directory(cache->graveyard); | |
163 | cache->graveyard = NULL; | |
164 | error_unsupported: | |
165 | cachefiles_put_directory(cache->store); | |
166 | cache->store = NULL; | |
167 | mntput(cache->mnt); | |
168 | cache->mnt = NULL; | |
169 | dput(root); | |
170 | error_open_root: | |
171 | cachefiles_end_secure(cache, saved_cred); | |
e21a2f17 BL |
172 | put_cred(cache->cache_cred); |
173 | cache->cache_cred = NULL; | |
d1065b0a DH |
174 | error_getsec: |
175 | fscache_relinquish_cache(cache_cookie); | |
176 | cache->cache = NULL; | |
177 | pr_err("Failed to register: %d\n", ret); | |
178 | return ret; | |
179 | } | |
180 | ||
80f94f29 DH |
181 | /* |
182 | * See if we have space for a number of pages and/or a number of files in the | |
183 | * cache | |
184 | */ | |
185 | int cachefiles_has_space(struct cachefiles_cache *cache, | |
3929eca7 DH |
186 | unsigned fnr, unsigned bnr, |
187 | enum cachefiles_has_space_for reason) | |
80f94f29 DH |
188 | { |
189 | struct kstatfs stats; | |
190 | u64 b_avail, b_writing; | |
191 | int ret; | |
192 | ||
193 | struct path path = { | |
194 | .mnt = cache->mnt, | |
195 | .dentry = cache->mnt->mnt_root, | |
196 | }; | |
197 | ||
198 | //_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u", | |
199 | // (unsigned long long) cache->frun, | |
200 | // (unsigned long long) cache->fcull, | |
201 | // (unsigned long long) cache->fstop, | |
202 | // (unsigned long long) cache->brun, | |
203 | // (unsigned long long) cache->bcull, | |
204 | // (unsigned long long) cache->bstop, | |
205 | // fnr, bnr); | |
206 | ||
207 | /* find out how many pages of blockdev are available */ | |
208 | memset(&stats, 0, sizeof(stats)); | |
209 | ||
210 | ret = vfs_statfs(&path, &stats); | |
211 | if (ret < 0) { | |
212 | trace_cachefiles_vfs_error(NULL, d_inode(path.dentry), ret, | |
213 | cachefiles_trace_statfs_error); | |
214 | if (ret == -EIO) | |
215 | cachefiles_io_error(cache, "statfs failed"); | |
216 | _leave(" = %d", ret); | |
217 | return ret; | |
218 | } | |
219 | ||
5638b067 | 220 | b_avail = stats.f_bavail; |
80f94f29 DH |
221 | b_writing = atomic_long_read(&cache->b_writing); |
222 | if (b_avail > b_writing) | |
223 | b_avail -= b_writing; | |
224 | else | |
225 | b_avail = 0; | |
226 | ||
227 | //_debug("avail %llu,%llu", | |
228 | // (unsigned long long)stats.f_ffree, | |
229 | // (unsigned long long)b_avail); | |
230 | ||
231 | /* see if there is sufficient space */ | |
232 | if (stats.f_ffree > fnr) | |
233 | stats.f_ffree -= fnr; | |
234 | else | |
235 | stats.f_ffree = 0; | |
236 | ||
237 | if (b_avail > bnr) | |
238 | b_avail -= bnr; | |
239 | else | |
240 | b_avail = 0; | |
241 | ||
242 | ret = -ENOBUFS; | |
243 | if (stats.f_ffree < cache->fstop || | |
244 | b_avail < cache->bstop) | |
3929eca7 | 245 | goto stop_and_begin_cull; |
80f94f29 DH |
246 | |
247 | ret = 0; | |
248 | if (stats.f_ffree < cache->fcull || | |
249 | b_avail < cache->bcull) | |
250 | goto begin_cull; | |
251 | ||
252 | if (test_bit(CACHEFILES_CULLING, &cache->flags) && | |
253 | stats.f_ffree >= cache->frun && | |
254 | b_avail >= cache->brun && | |
255 | test_and_clear_bit(CACHEFILES_CULLING, &cache->flags) | |
256 | ) { | |
257 | _debug("cease culling"); | |
258 | cachefiles_state_changed(cache); | |
259 | } | |
260 | ||
261 | //_leave(" = 0"); | |
262 | return 0; | |
263 | ||
3929eca7 DH |
264 | stop_and_begin_cull: |
265 | switch (reason) { | |
266 | case cachefiles_has_space_for_write: | |
267 | fscache_count_no_write_space(); | |
268 | break; | |
269 | case cachefiles_has_space_for_create: | |
270 | fscache_count_no_create_space(); | |
271 | break; | |
272 | default: | |
273 | break; | |
274 | } | |
80f94f29 DH |
275 | begin_cull: |
276 | if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) { | |
277 | _debug("### CULL CACHE ###"); | |
278 | cachefiles_state_changed(cache); | |
279 | } | |
280 | ||
281 | _leave(" = %d", ret); | |
282 | return ret; | |
283 | } | |
d1065b0a | 284 | |
1f08c925 DH |
285 | /* |
286 | * Mark all the objects as being out of service and queue them all for cleanup. | |
287 | */ | |
288 | static void cachefiles_withdraw_objects(struct cachefiles_cache *cache) | |
289 | { | |
290 | struct cachefiles_object *object; | |
291 | unsigned int count = 0; | |
292 | ||
293 | _enter(""); | |
294 | ||
295 | spin_lock(&cache->object_list_lock); | |
296 | ||
297 | while (!list_empty(&cache->object_list)) { | |
298 | object = list_first_entry(&cache->object_list, | |
299 | struct cachefiles_object, cache_link); | |
300 | cachefiles_see_object(object, cachefiles_obj_see_withdrawal); | |
301 | list_del_init(&object->cache_link); | |
302 | fscache_withdraw_cookie(object->cookie); | |
303 | count++; | |
304 | if ((count & 63) == 0) { | |
305 | spin_unlock(&cache->object_list_lock); | |
306 | cond_resched(); | |
307 | spin_lock(&cache->object_list_lock); | |
308 | } | |
309 | } | |
310 | ||
311 | spin_unlock(&cache->object_list_lock); | |
312 | _leave(" [%u objs]", count); | |
313 | } | |
314 | ||
fe2140e2 | 315 | /* |
5d8f8057 BL |
316 | * Withdraw fscache volumes. |
317 | */ | |
318 | static void cachefiles_withdraw_fscache_volumes(struct cachefiles_cache *cache) | |
319 | { | |
320 | struct list_head *cur; | |
321 | struct cachefiles_volume *volume; | |
322 | struct fscache_volume *vcookie; | |
323 | ||
324 | _enter(""); | |
325 | retry: | |
326 | spin_lock(&cache->object_list_lock); | |
327 | list_for_each(cur, &cache->volumes) { | |
328 | volume = list_entry(cur, struct cachefiles_volume, cache_link); | |
329 | ||
330 | if (atomic_read(&volume->vcookie->n_accesses) == 0) | |
331 | continue; | |
332 | ||
333 | vcookie = fscache_try_get_volume(volume->vcookie, | |
334 | fscache_volume_get_withdraw); | |
335 | if (vcookie) { | |
336 | spin_unlock(&cache->object_list_lock); | |
337 | fscache_withdraw_volume(vcookie); | |
338 | fscache_put_volume(vcookie, fscache_volume_put_withdraw); | |
339 | goto retry; | |
340 | } | |
341 | } | |
342 | spin_unlock(&cache->object_list_lock); | |
343 | ||
344 | _leave(""); | |
345 | } | |
346 | ||
347 | /* | |
348 | * Withdraw cachefiles volumes. | |
fe2140e2 DH |
349 | */ |
350 | static void cachefiles_withdraw_volumes(struct cachefiles_cache *cache) | |
351 | { | |
352 | _enter(""); | |
353 | ||
354 | for (;;) { | |
522018a0 | 355 | struct fscache_volume *vcookie = NULL; |
fe2140e2 DH |
356 | struct cachefiles_volume *volume = NULL; |
357 | ||
358 | spin_lock(&cache->object_list_lock); | |
359 | if (!list_empty(&cache->volumes)) { | |
360 | volume = list_first_entry(&cache->volumes, | |
361 | struct cachefiles_volume, cache_link); | |
522018a0 BL |
362 | vcookie = fscache_try_get_volume(volume->vcookie, |
363 | fscache_volume_get_withdraw); | |
364 | if (!vcookie) { | |
365 | spin_unlock(&cache->object_list_lock); | |
366 | cpu_relax(); | |
367 | continue; | |
368 | } | |
fe2140e2 DH |
369 | list_del_init(&volume->cache_link); |
370 | } | |
371 | spin_unlock(&cache->object_list_lock); | |
372 | if (!volume) | |
373 | break; | |
374 | ||
375 | cachefiles_withdraw_volume(volume); | |
522018a0 | 376 | fscache_put_volume(vcookie, fscache_volume_put_withdraw); |
fe2140e2 DH |
377 | } |
378 | ||
379 | _leave(""); | |
380 | } | |
381 | ||
d1065b0a DH |
382 | /* |
383 | * Sync a cache to backing disk. | |
384 | */ | |
385 | static void cachefiles_sync_cache(struct cachefiles_cache *cache) | |
386 | { | |
387 | const struct cred *saved_cred; | |
388 | int ret; | |
389 | ||
390 | _enter("%s", cache->cache->name); | |
391 | ||
392 | /* make sure all pages pinned by operations on behalf of the netfs are | |
393 | * written to disc */ | |
394 | cachefiles_begin_secure(cache, &saved_cred); | |
395 | down_read(&cache->mnt->mnt_sb->s_umount); | |
396 | ret = sync_filesystem(cache->mnt->mnt_sb); | |
397 | up_read(&cache->mnt->mnt_sb->s_umount); | |
398 | cachefiles_end_secure(cache, saved_cred); | |
399 | ||
400 | if (ret == -EIO) | |
401 | cachefiles_io_error(cache, | |
402 | "Attempt to sync backing fs superblock returned error %d", | |
403 | ret); | |
404 | } | |
405 | ||
406 | /* | |
407 | * Withdraw cache objects. | |
408 | */ | |
409 | void cachefiles_withdraw_cache(struct cachefiles_cache *cache) | |
410 | { | |
411 | struct fscache_cache *fscache = cache->cache; | |
412 | ||
413 | pr_info("File cache on %s unregistering\n", fscache->name); | |
414 | ||
415 | fscache_withdraw_cache(fscache); | |
5d8f8057 | 416 | cachefiles_withdraw_fscache_volumes(cache); |
d1065b0a DH |
417 | |
418 | /* we now have to destroy all the active objects pertaining to this | |
419 | * cache - which we do by passing them off to thread pool to be | |
420 | * disposed of */ | |
1f08c925 | 421 | cachefiles_withdraw_objects(cache); |
d1065b0a DH |
422 | fscache_wait_for_objects(fscache); |
423 | ||
fe2140e2 | 424 | cachefiles_withdraw_volumes(cache); |
d1065b0a DH |
425 | cachefiles_sync_cache(cache); |
426 | cache->cache = NULL; | |
427 | fscache_relinquish_cache(fscache); | |
428 | } |