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>
 18#include <linux/debugfs.h>
 19#include <linux/cleancache.h>
 20
 21/*
 22 * cleancache_ops is set by cleancache_register_ops to contain the pointers
 23 * to the cleancache "backend" implementation functions.
 
 
 
 24 */
 25static const struct cleancache_ops *cleancache_ops __read_mostly;
 
 26
 27/*
 28 * Counters available via /sys/kernel/debug/cleancache (if debugfs is
 29 * properly configured.  These are for information only so are not protected
 30 * against increment races.
 31 */
 32static u64 cleancache_succ_gets;
 33static u64 cleancache_failed_gets;
 34static u64 cleancache_puts;
 35static u64 cleancache_invalidates;
 36
 37static void cleancache_register_ops_sb(struct super_block *sb, void *unused)
 38{
 39	switch (sb->cleancache_poolid) {
 40	case CLEANCACHE_NO_BACKEND:
 41		__cleancache_init_fs(sb);
 42		break;
 43	case CLEANCACHE_NO_BACKEND_SHARED:
 44		__cleancache_init_shared_fs(sb);
 45		break;
 46	}
 47}
 48
 49/*
 50 * Register operations for cleancache. Returns 0 on success.
 
 51 */
 52int cleancache_register_ops(const struct cleancache_ops *ops)
 53{
 54	if (cmpxchg(&cleancache_ops, NULL, ops))
 55		return -EBUSY;
 56
 57	/*
 58	 * A cleancache backend can be built as a module and hence loaded after
 59	 * a cleancache enabled filesystem has called cleancache_init_fs. To
 60	 * handle such a scenario, here we call ->init_fs or ->init_shared_fs
 61	 * for each active super block. To differentiate between local and
 62	 * shared filesystems, we temporarily initialize sb->cleancache_poolid
 63	 * to CLEANCACHE_NO_BACKEND or CLEANCACHE_NO_BACKEND_SHARED
 64	 * respectively in case there is no backend registered at the time
 65	 * cleancache_init_fs or cleancache_init_shared_fs is called.
 66	 *
 67	 * Since filesystems can be mounted concurrently with cleancache
 68	 * backend registration, we have to be careful to guarantee that all
 69	 * cleancache enabled filesystems that has been mounted by the time
 70	 * cleancache_register_ops is called has got and all mounted later will
 71	 * get cleancache_poolid. This is assured by the following statements
 72	 * tied together:
 73	 *
 74	 * a) iterate_supers skips only those super blocks that has started
 75	 *    ->kill_sb
 76	 *
 77	 * b) if iterate_supers encounters a super block that has not finished
 78	 *    ->mount yet, it waits until it is finished
 79	 *
 80	 * c) cleancache_init_fs is called from ->mount and
 81	 *    cleancache_invalidate_fs is called from ->kill_sb
 82	 *
 83	 * d) we call iterate_supers after cleancache_ops has been set
 84	 *
 85	 * From a) it follows that if iterate_supers skips a super block, then
 86	 * either the super block is already dead, in which case we do not need
 87	 * to bother initializing cleancache for it, or it was mounted after we
 88	 * initiated iterate_supers. In the latter case, it must have seen
 89	 * cleancache_ops set according to d) and initialized cleancache from
 90	 * ->mount by itself according to c). This proves that we call
 91	 * ->init_fs at least once for each active super block.
 92	 *
 93	 * From b) and c) it follows that if iterate_supers encounters a super
 94	 * block that has already started ->init_fs, it will wait until ->mount
 95	 * and hence ->init_fs has finished, then check cleancache_poolid, see
 96	 * that it has already been set and therefore do nothing. This proves
 97	 * that we call ->init_fs no more than once for each super block.
 98	 *
 99	 * Combined together, the last two paragraphs prove the function
100	 * correctness.
101	 *
102	 * Note that various cleancache callbacks may proceed before this
103	 * function is called or even concurrently with it, but since
104	 * CLEANCACHE_NO_BACKEND is negative, they will all result in a noop
105	 * until the corresponding ->init_fs has been actually called and
106	 * cleancache_ops has been set.
107	 */
108	iterate_supers(cleancache_register_ops_sb, NULL);
109	return 0;
110}
111EXPORT_SYMBOL(cleancache_register_ops);
112
113/* Called by a cleancache-enabled filesystem at time of mount */
114void __cleancache_init_fs(struct super_block *sb)
115{
116	int pool_id = CLEANCACHE_NO_BACKEND;
117
118	if (cleancache_ops) {
119		pool_id = cleancache_ops->init_fs(PAGE_SIZE);
120		if (pool_id < 0)
121			pool_id = CLEANCACHE_NO_POOL;
122	}
123	sb->cleancache_poolid = pool_id;
124}
125EXPORT_SYMBOL(__cleancache_init_fs);
126
127/* Called by a cleancache-enabled clustered filesystem at time of mount */
128void __cleancache_init_shared_fs(struct super_block *sb)
129{
130	int pool_id = CLEANCACHE_NO_BACKEND_SHARED;
131
132	if (cleancache_ops) {
133		pool_id = cleancache_ops->init_shared_fs(sb->s_uuid, PAGE_SIZE);
134		if (pool_id < 0)
135			pool_id = CLEANCACHE_NO_POOL;
136	}
137	sb->cleancache_poolid = pool_id;
138}
139EXPORT_SYMBOL(__cleancache_init_shared_fs);
140
141/*
142 * If the filesystem uses exportable filehandles, use the filehandle as
143 * the key, else use the inode number.
144 */
145static int cleancache_get_key(struct inode *inode,
146			      struct cleancache_filekey *key)
147{
148	int (*fhfn)(struct inode *, __u32 *fh, int *, struct inode *);
149	int len = 0, maxlen = CLEANCACHE_KEY_MAX;
150	struct super_block *sb = inode->i_sb;
151
152	key->u.ino = inode->i_ino;
153	if (sb->s_export_op != NULL) {
154		fhfn = sb->s_export_op->encode_fh;
155		if  (fhfn) {
156			len = (*fhfn)(inode, &key->u.fh[0], &maxlen, NULL);
157			if (len <= FILEID_ROOT || len == FILEID_INVALID)
 
 
158				return -1;
159			if (maxlen > CLEANCACHE_KEY_MAX)
160				return -1;
161		}
162	}
163	return 0;
164}
165
166/*
167 * "Get" data from cleancache associated with the poolid/inode/index
168 * that were specified when the data was put to cleanache and, if
169 * successful, use it to fill the specified page with data and return 0.
170 * The pageframe is unchanged and returns -1 if the get fails.
171 * Page must be locked by caller.
172 *
173 * The function has two checks before any action is taken - whether
174 * a backend is registered and whether the sb->cleancache_poolid
175 * is correct.
176 */
177int __cleancache_get_page(struct page *page)
178{
179	int ret = -1;
180	int pool_id;
181	struct cleancache_filekey key = { .u.key = { 0 } };
182
183	if (!cleancache_ops) {
184		cleancache_failed_gets++;
185		goto out;
186	}
187
188	VM_BUG_ON_PAGE(!PageLocked(page), page);
189	pool_id = page->mapping->host->i_sb->cleancache_poolid;
190	if (pool_id < 0)
191		goto out;
192
193	if (cleancache_get_key(page->mapping->host, &key) < 0)
194		goto out;
195
196	ret = cleancache_ops->get_page(pool_id, key, page->index, page);
197	if (ret == 0)
198		cleancache_succ_gets++;
199	else
200		cleancache_failed_gets++;
201out:
202	return ret;
203}
204EXPORT_SYMBOL(__cleancache_get_page);
205
206/*
207 * "Put" data from a page to cleancache and associate it with the
208 * (previously-obtained per-filesystem) poolid and the page's,
209 * inode and page index.  Page must be locked.  Note that a put_page
210 * always "succeeds", though a subsequent get_page may succeed or fail.
211 *
212 * The function has two checks before any action is taken - whether
213 * a backend is registered and whether the sb->cleancache_poolid
214 * is correct.
215 */
216void __cleancache_put_page(struct page *page)
217{
218	int pool_id;
219	struct cleancache_filekey key = { .u.key = { 0 } };
220
221	if (!cleancache_ops) {
222		cleancache_puts++;
223		return;
224	}
225
226	VM_BUG_ON_PAGE(!PageLocked(page), page);
227	pool_id = page->mapping->host->i_sb->cleancache_poolid;
228	if (pool_id >= 0 &&
229		cleancache_get_key(page->mapping->host, &key) >= 0) {
230		cleancache_ops->put_page(pool_id, key, page->index, page);
231		cleancache_puts++;
232	}
233}
234EXPORT_SYMBOL(__cleancache_put_page);
235
236/*
237 * Invalidate any data from cleancache associated with the poolid and the
238 * page's inode and page index so that a subsequent "get" will fail.
239 *
240 * The function has two checks before any action is taken - whether
241 * a backend is registered and whether the sb->cleancache_poolid
242 * is correct.
243 */
244void __cleancache_invalidate_page(struct address_space *mapping,
245					struct page *page)
246{
247	/* careful... page->mapping is NULL sometimes when this is called */
248	int pool_id = mapping->host->i_sb->cleancache_poolid;
249	struct cleancache_filekey key = { .u.key = { 0 } };
250
251	if (!cleancache_ops)
252		return;
253
254	if (pool_id >= 0) {
255		VM_BUG_ON_PAGE(!PageLocked(page), page);
256		if (cleancache_get_key(mapping->host, &key) >= 0) {
257			cleancache_ops->invalidate_page(pool_id,
258					key, page->index);
259			cleancache_invalidates++;
260		}
261	}
262}
263EXPORT_SYMBOL(__cleancache_invalidate_page);
264
265/*
266 * Invalidate all data from cleancache associated with the poolid and the
267 * mappings's inode so that all subsequent gets to this poolid/inode
268 * will fail.
269 *
270 * The function has two checks before any action is taken - whether
271 * a backend is registered and whether the sb->cleancache_poolid
272 * is correct.
273 */
274void __cleancache_invalidate_inode(struct address_space *mapping)
275{
276	int pool_id = mapping->host->i_sb->cleancache_poolid;
277	struct cleancache_filekey key = { .u.key = { 0 } };
278
279	if (!cleancache_ops)
280		return;
281
282	if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0)
283		cleancache_ops->invalidate_inode(pool_id, key);
284}
285EXPORT_SYMBOL(__cleancache_invalidate_inode);
286
287/*
288 * Called by any cleancache-enabled filesystem at time of unmount;
289 * note that pool_id is surrendered and may be returned by a subsequent
290 * cleancache_init_fs or cleancache_init_shared_fs.
291 */
292void __cleancache_invalidate_fs(struct super_block *sb)
293{
294	int pool_id;
 
 
 
 
 
 
295
296	pool_id = sb->cleancache_poolid;
297	sb->cleancache_poolid = CLEANCACHE_NO_POOL;
298
299	if (cleancache_ops && pool_id >= 0)
300		cleancache_ops->invalidate_fs(pool_id);
301}
302EXPORT_SYMBOL(__cleancache_invalidate_fs);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
303
304static int __init init_cleancache(void)
305{
306#ifdef CONFIG_DEBUG_FS
307	struct dentry *root = debugfs_create_dir("cleancache", NULL);
308	if (root == NULL)
309		return -ENXIO;
310	debugfs_create_u64("succ_gets", S_IRUGO, root, &cleancache_succ_gets);
311	debugfs_create_u64("failed_gets", S_IRUGO,
312				root, &cleancache_failed_gets);
313	debugfs_create_u64("puts", S_IRUGO, root, &cleancache_puts);
314	debugfs_create_u64("invalidates", S_IRUGO,
315				root, &cleancache_invalidates);
316#endif
317	return 0;
318}
319module_init(init_cleancache)

  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>
 
 18#include <linux/cleancache.h>
 19
 20/*
 21 * This global enablement flag may be read thousands of times per second
 22 * by cleancache_get/put/flush even on systems where cleancache_ops
 23 * is not claimed (e.g. cleancache is config'ed on but remains
 24 * disabled), so is preferred to the slower alternative: a function
 25 * call that checks a non-global.
 26 */
 27int cleancache_enabled;
 28EXPORT_SYMBOL(cleancache_enabled);
 29
 30/*
 31 * cleancache_ops is set by cleancache_ops_register to contain the pointers
 32 * to the cleancache "backend" implementation functions.
 
 33 */
 34static struct cleancache_ops cleancache_ops;
 
 
 
 35
 36/* useful stats available in /sys/kernel/mm/cleancache */
 37static unsigned long cleancache_succ_gets;
 38static unsigned long cleancache_failed_gets;
 39static unsigned long cleancache_puts;
 40static unsigned long cleancache_flushes;
 
 
 
 
 
 
 41
 42/*
 43 * register operations for cleancache, returning previous thus allowing
 44 * detection of multiple backends and possible nesting
 45 */
 46struct cleancache_ops cleancache_register_ops(struct cleancache_ops *ops)
 47{
 48	struct cleancache_ops old = cleancache_ops;
 
 49
 50	cleancache_ops = *ops;
 51	cleancache_enabled = 1;
 52	return old;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 53}
 54EXPORT_SYMBOL(cleancache_register_ops);
 55
 56/* Called by a cleancache-enabled filesystem at time of mount */
 57void __cleancache_init_fs(struct super_block *sb)
 58{
 59	sb->cleancache_poolid = (*cleancache_ops.init_fs)(PAGE_SIZE);
 
 
 
 
 
 
 
 60}
 61EXPORT_SYMBOL(__cleancache_init_fs);
 62
 63/* Called by a cleancache-enabled clustered filesystem at time of mount */
 64void __cleancache_init_shared_fs(char *uuid, struct super_block *sb)
 65{
 66	sb->cleancache_poolid =
 67		(*cleancache_ops.init_shared_fs)(uuid, PAGE_SIZE);
 
 
 
 
 
 
 68}
 69EXPORT_SYMBOL(__cleancache_init_shared_fs);
 70
 71/*
 72 * If the filesystem uses exportable filehandles, use the filehandle as
 73 * the key, else use the inode number.
 74 */
 75static int cleancache_get_key(struct inode *inode,
 76			      struct cleancache_filekey *key)
 77{
 78	int (*fhfn)(struct dentry *, __u32 *fh, int *, int);
 79	int len = 0, maxlen = CLEANCACHE_KEY_MAX;
 80	struct super_block *sb = inode->i_sb;
 81
 82	key->u.ino = inode->i_ino;
 83	if (sb->s_export_op != NULL) {
 84		fhfn = sb->s_export_op->encode_fh;
 85		if  (fhfn) {
 86			struct dentry d;
 87			d.d_inode = inode;
 88			len = (*fhfn)(&d, &key->u.fh[0], &maxlen, 0);
 89			if (len <= 0 || len == 255)
 90				return -1;
 91			if (maxlen > CLEANCACHE_KEY_MAX)
 92				return -1;
 93		}
 94	}
 95	return 0;
 96}
 97
 98/*
 99 * "Get" data from cleancache associated with the poolid/inode/index
100 * that were specified when the data was put to cleanache and, if
101 * successful, use it to fill the specified page with data and return 0.
102 * The pageframe is unchanged and returns -1 if the get fails.
103 * Page must be locked by caller.
 
 
 
 
104 */
105int __cleancache_get_page(struct page *page)
106{
107	int ret = -1;
108	int pool_id;
109	struct cleancache_filekey key = { .u.key = { 0 } };
110
111	VM_BUG_ON(!PageLocked(page));
 
 
 
 
 
112	pool_id = page->mapping->host->i_sb->cleancache_poolid;
113	if (pool_id < 0)
114		goto out;
115
116	if (cleancache_get_key(page->mapping->host, &key) < 0)
117		goto out;
118
119	ret = (*cleancache_ops.get_page)(pool_id, key, page->index, page);
120	if (ret == 0)
121		cleancache_succ_gets++;
122	else
123		cleancache_failed_gets++;
124out:
125	return ret;
126}
127EXPORT_SYMBOL(__cleancache_get_page);
128
129/*
130 * "Put" data from a page to cleancache and associate it with the
131 * (previously-obtained per-filesystem) poolid and the page's,
132 * inode and page index.  Page must be locked.  Note that a put_page
133 * always "succeeds", though a subsequent get_page may succeed or fail.
 
 
 
 
134 */
135void __cleancache_put_page(struct page *page)
136{
137	int pool_id;
138	struct cleancache_filekey key = { .u.key = { 0 } };
139
140	VM_BUG_ON(!PageLocked(page));
 
 
 
 
 
141	pool_id = page->mapping->host->i_sb->cleancache_poolid;
142	if (pool_id >= 0 &&
143	      cleancache_get_key(page->mapping->host, &key) >= 0) {
144		(*cleancache_ops.put_page)(pool_id, key, page->index, page);
145		cleancache_puts++;
146	}
147}
148EXPORT_SYMBOL(__cleancache_put_page);
149
150/*
151 * Flush any data from cleancache associated with the poolid and the
152 * page's inode and page index so that a subsequent "get" will fail.
 
 
 
 
153 */
154void __cleancache_flush_page(struct address_space *mapping, struct page *page)
 
155{
156	/* careful... page->mapping is NULL sometimes when this is called */
157	int pool_id = mapping->host->i_sb->cleancache_poolid;
158	struct cleancache_filekey key = { .u.key = { 0 } };
159
 
 
 
160	if (pool_id >= 0) {
161		VM_BUG_ON(!PageLocked(page));
162		if (cleancache_get_key(mapping->host, &key) >= 0) {
163			(*cleancache_ops.flush_page)(pool_id, key, page->index);
164			cleancache_flushes++;
 
165		}
166	}
167}
168EXPORT_SYMBOL(__cleancache_flush_page);
169
170/*
171 * Flush all data from cleancache associated with the poolid and the
172 * mappings's inode so that all subsequent gets to this poolid/inode
173 * will fail.
 
 
 
 
174 */
175void __cleancache_flush_inode(struct address_space *mapping)
176{
177	int pool_id = mapping->host->i_sb->cleancache_poolid;
178	struct cleancache_filekey key = { .u.key = { 0 } };
179
 
 
 
180	if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0)
181		(*cleancache_ops.flush_inode)(pool_id, key);
182}
183EXPORT_SYMBOL(__cleancache_flush_inode);
184
185/*
186 * Called by any cleancache-enabled filesystem at time of unmount;
187 * note that pool_id is surrendered and may be reutrned by a subsequent
188 * cleancache_init_fs or cleancache_init_shared_fs
189 */
190void __cleancache_flush_fs(struct super_block *sb)
191{
192	if (sb->cleancache_poolid >= 0) {
193		int old_poolid = sb->cleancache_poolid;
194		sb->cleancache_poolid = -1;
195		(*cleancache_ops.flush_fs)(old_poolid);
196	}
197}
198EXPORT_SYMBOL(__cleancache_flush_fs);
199
200#ifdef CONFIG_SYSFS
 
201
202/* see Documentation/ABI/xxx/sysfs-kernel-mm-cleancache */
203
204#define CLEANCACHE_SYSFS_RO(_name) \
205	static ssize_t cleancache_##_name##_show(struct kobject *kobj, \
206				struct kobj_attribute *attr, char *buf) \
207	{ \
208		return sprintf(buf, "%lu\n", cleancache_##_name); \
209	} \
210	static struct kobj_attribute cleancache_##_name##_attr = { \
211		.attr = { .name = __stringify(_name), .mode = 0444 }, \
212		.show = cleancache_##_name##_show, \
213	}
214
215CLEANCACHE_SYSFS_RO(succ_gets);
216CLEANCACHE_SYSFS_RO(failed_gets);
217CLEANCACHE_SYSFS_RO(puts);
218CLEANCACHE_SYSFS_RO(flushes);
219
220static struct attribute *cleancache_attrs[] = {
221	&cleancache_succ_gets_attr.attr,
222	&cleancache_failed_gets_attr.attr,
223	&cleancache_puts_attr.attr,
224	&cleancache_flushes_attr.attr,
225	NULL,
226};
227
228static struct attribute_group cleancache_attr_group = {
229	.attrs = cleancache_attrs,
230	.name = "cleancache",
231};
232
233#endif /* CONFIG_SYSFS */
234
235static int __init init_cleancache(void)
236{
237#ifdef CONFIG_SYSFS
238	int err;
239
240	err = sysfs_create_group(mm_kobj, &cleancache_attr_group);
241#endif /* CONFIG_SYSFS */
 
 
 
 
 
 
242	return 0;
243}
244module_init(init_cleancache)