[deliverable/linux.git] / fs / cachefiles / bind.c

/* Bind and unbind a cache from the filesystem backing it
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/statfs.h>
#include <linux/ctype.h>
#include "internal.h"

static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);

/*
 * bind a directory as a cache
 */
int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
{
	_enter("{%u,%u,%u,%u,%u,%u},%s",
	       cache->frun_percent,
	       cache->fcull_percent,
	       cache->fstop_percent,
	       cache->brun_percent,
	       cache->bcull_percent,
	       cache->bstop_percent,
	       args);

	/* start by checking things over */
	ASSERT(cache->fstop_percent >= 0 &&
	       cache->fstop_percent < cache->fcull_percent &&
	       cache->fcull_percent < cache->frun_percent &&
	       cache->frun_percent  < 100);

	ASSERT(cache->bstop_percent >= 0 &&
	       cache->bstop_percent < cache->bcull_percent &&
	       cache->bcull_percent < cache->brun_percent &&
	       cache->brun_percent  < 100);

	if (*args) {
		kerror("'bind' command doesn't take an argument");
		return -EINVAL;
	}

	if (!cache->rootdirname) {
		kerror("No cache directory specified");
		return -EINVAL;
	}

	/* don't permit already bound caches to be re-bound */
	if (test_bit(CACHEFILES_READY, &cache->flags)) {
		kerror("Cache already bound");
		return -EBUSY;
	}

	/* make sure we have copies of the tag and dirname strings */
	if (!cache->tag) {
		/* the tag string is released by the fops->release()
		 * function, so we don't release it on error here */
		cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
		if (!cache->tag)
			return -ENOMEM;
	}

	/* add the cache */
	return cachefiles_daemon_add_cache(cache);
}

/*
 * add a cache
 */
static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
{
	struct cachefiles_object *fsdef;
	struct path path;
	struct kstatfs stats;
	struct dentry *graveyard, *cachedir, *root;
	const struct cred *saved_cred;
	int ret;

	_enter("");

	/* we want to work under the module's security ID */
	ret = cachefiles_get_security_ID(cache);
	if (ret < 0)
		return ret;

	cachefiles_begin_secure(cache, &saved_cred);

	/* allocate the root index object */
	ret = -ENOMEM;

	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
	if (!fsdef)
		goto error_root_object;

	ASSERTCMP(fsdef->backer, ==, NULL);

	atomic_set(&fsdef->usage, 1);
	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;

	_debug("- fsdef %p", fsdef);

	/* look up the directory at the root of the cache */
	ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
	if (ret < 0)
		goto error_open_root;

	cache->mnt = path.mnt;
	root = path.dentry;

	/* check parameters */
	ret = -EOPNOTSUPP;
	if (!root->d_inode ||
	    !root->d_inode->i_op ||
	    !root->d_inode->i_op->lookup ||
	    !root->d_inode->i_op->mkdir ||
	    !root->d_inode->i_op->setxattr ||
	    !root->d_inode->i_op->getxattr ||
	    !root->d_sb->s_op ||
	    !root->d_sb->s_op->statfs ||
	    !root->d_sb->s_op->sync_fs)
		goto error_unsupported;

	ret = -EROFS;
	if (root->d_sb->s_flags & MS_RDONLY)
		goto error_unsupported;

	/* determine the security of the on-disk cache as this governs
	 * security ID of files we create */
	ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
	if (ret < 0)
		goto error_unsupported;

	/* get the cache size and blocksize */
	ret = vfs_statfs(&path, &stats);
	if (ret < 0)
		goto error_unsupported;

	ret = -ERANGE;
	if (stats.f_bsize <= 0)
		goto error_unsupported;

	ret = -EOPNOTSUPP;
	if (stats.f_bsize > PAGE_SIZE)
		goto error_unsupported;

	cache->bsize = stats.f_bsize;
	cache->bshift = 0;
	if (stats.f_bsize < PAGE_SIZE)
		cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);

	_debug("blksize %u (shift %u)",
	       cache->bsize, cache->bshift);

	_debug("size %llu, avail %llu",
	       (unsigned long long) stats.f_blocks,
	       (unsigned long long) stats.f_bavail);

	/* set up caching limits */
	do_div(stats.f_files, 100);
	cache->fstop = stats.f_files * cache->fstop_percent;
	cache->fcull = stats.f_files * cache->fcull_percent;
	cache->frun  = stats.f_files * cache->frun_percent;

	_debug("limits {%llu,%llu,%llu} files",
	       (unsigned long long) cache->frun,
	       (unsigned long long) cache->fcull,
	       (unsigned long long) cache->fstop);

	stats.f_blocks >>= cache->bshift;
	do_div(stats.f_blocks, 100);
	cache->bstop = stats.f_blocks * cache->bstop_percent;
	cache->bcull = stats.f_blocks * cache->bcull_percent;
	cache->brun  = stats.f_blocks * cache->brun_percent;

	_debug("limits {%llu,%llu,%llu} blocks",
	       (unsigned long long) cache->brun,
	       (unsigned long long) cache->bcull,
	       (unsigned long long) cache->bstop);

	/* get the cache directory and check its type */
	cachedir = cachefiles_get_directory(cache, root, "cache");
	if (IS_ERR(cachedir)) {
		ret = PTR_ERR(cachedir);
		goto error_unsupported;
	}

	fsdef->dentry = cachedir;
	fsdef->fscache.cookie = NULL;

	ret = cachefiles_check_object_type(fsdef);
	if (ret < 0)
		goto error_unsupported;

	/* get the graveyard directory */
	graveyard = cachefiles_get_directory(cache, root, "graveyard");
	if (IS_ERR(graveyard)) {
		ret = PTR_ERR(graveyard);
		goto error_unsupported;
	}

	cache->graveyard = graveyard;

	/* publish the cache */
	fscache_init_cache(&cache->cache,
			   &cachefiles_cache_ops,
			   "%s",
			   fsdef->dentry->d_sb->s_id);

	fscache_object_init(&fsdef->fscache, NULL, &cache->cache);

	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
	if (ret < 0)
		goto error_add_cache;

	/* done */
	set_bit(CACHEFILES_READY, &cache->flags);
	dput(root);

	printk(KERN_INFO "CacheFiles:"
	       " File cache on %s registered\n",
	       cache->cache.identifier);

	/* check how much space the cache has */
	cachefiles_has_space(cache, 0, 0);
	cachefiles_end_secure(cache, saved_cred);
	return 0;

error_add_cache:
	dput(cache->graveyard);
	cache->graveyard = NULL;
error_unsupported:
	mntput(cache->mnt);
	cache->mnt = NULL;
	dput(fsdef->dentry);
	fsdef->dentry = NULL;
	dput(root);
error_open_root:
	kmem_cache_free(cachefiles_object_jar, fsdef);
error_root_object:
	cachefiles_end_secure(cache, saved_cred);
	kerror("Failed to register: %d", ret);
	return ret;
}

/*
 * unbind a cache on fd release
 */
void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
{
	_enter("");

	if (test_bit(CACHEFILES_READY, &cache->flags)) {
		printk(KERN_INFO "CacheFiles:"
		       " File cache on %s unregistering\n",
		       cache->cache.identifier);

		fscache_withdraw_cache(&cache->cache);
	}

	dput(cache->graveyard);
	mntput(cache->mnt);

	kfree(cache->rootdirname);
	kfree(cache->secctx);
	kfree(cache->tag);

	_leave("");
}
Commit	Line	Data
9ae326a6 DH	1	/* Bind and unbind a cache from the filesystem backing it
	2	*
	3	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public Licence
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the Licence, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/init.h>
	14	#include <linux/sched.h>
	15	#include <linux/completion.h>
	16	#include <linux/slab.h>
	17	#include <linux/fs.h>
	18	#include <linux/file.h>
	19	#include <linux/namei.h>
	20	#include <linux/mount.h>
	21	#include <linux/statfs.h>
	22	#include <linux/ctype.h>
	23	#include "internal.h"
	24
	25	static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
	26
	27	/*
	28	* bind a directory as a cache
	29	*/
	30	int cachefiles_daemon_bind(struct cachefiles_cache cache, char args)
	31	{
	32	_enter("{%u,%u,%u,%u,%u,%u},%s",
	33	cache->frun_percent,
	34	cache->fcull_percent,
	35	cache->fstop_percent,
	36	cache->brun_percent,
	37	cache->bcull_percent,
	38	cache->bstop_percent,
	39	args);
	40
	41	/* start by checking things over */
	42	ASSERT(cache->fstop_percent >= 0 &&
	43	cache->fstop_percent < cache->fcull_percent &&
	44	cache->fcull_percent < cache->frun_percent &&
	45	cache->frun_percent < 100);
	46
	47	ASSERT(cache->bstop_percent >= 0 &&
	48	cache->bstop_percent < cache->bcull_percent &&
	49	cache->bcull_percent < cache->brun_percent &&
	50	cache->brun_percent < 100);
	51
	52	if (*args) {
	53	kerror("'bind' command doesn't take an argument");
	54	return -EINVAL;
	55	}
	56
	57	if (!cache->rootdirname) {
	58	kerror("No cache directory specified");
	59	return -EINVAL;
	60	}
	61
	62	/* don't permit already bound caches to be re-bound */
	63	if (test_bit(CACHEFILES_READY, &cache->flags)) {
	64	kerror("Cache already bound");
65	return -EBUSY;
66	}
67
68	/* make sure we have copies of the tag and dirname strings */
69	if (!cache->tag) {
70	/* the tag string is released by the fops->release()
71	* function, so we don't release it on error here */
72	cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
73	if (!cache->tag)
74	return -ENOMEM;
75	}
76
77	/* add the cache */
78	return cachefiles_daemon_add_cache(cache);
79	}
80
81	/*
82	* add a cache
83	*/
84	static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
85	{
86	struct cachefiles_object *fsdef;
b0446be4	87	struct path path;
9ae326a6 DH	88	struct kstatfs stats;
	89	struct dentry graveyard, cachedir, *root;
	90	const struct cred *saved_cred;
	91	int ret;
	92
	93	_enter("");
	94
	95	/* we want to work under the module's security ID */
	96	ret = cachefiles_get_security_ID(cache);
	97	if (ret < 0)
	98	return ret;
	99
	100	cachefiles_begin_secure(cache, &saved_cred);
	101
	102	/* allocate the root index object */
	103	ret = -ENOMEM;
	104
	105	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
	106	if (!fsdef)
	107	goto error_root_object;
	108
	109	ASSERTCMP(fsdef->backer, ==, NULL);
	110
	111	atomic_set(&fsdef->usage, 1);
	112	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;
	113
	114	_debug("- fsdef %p", fsdef);
	115
	116	/* look up the directory at the root of the cache */
b0446be4	117	ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
9ae326a6 DH	118	if (ret < 0)
	119	goto error_open_root;
	120
b0446be4 AV	121	cache->mnt = path.mnt;
b0446be4 AV	122	root = path.dentry;
9ae326a6 DH	123
	124	/* check parameters */
	125	ret = -EOPNOTSUPP;
	126	if (!root->d_inode \|\|
	127	!root->d_inode->i_op \|\|
	128	!root->d_inode->i_op->lookup \|\|
	129	!root->d_inode->i_op->mkdir \|\|
	130	!root->d_inode->i_op->setxattr \|\|
	131	!root->d_inode->i_op->getxattr \|\|
9ae326a6 DH	132	!root->d_sb->s_op \|\|
	133	!root->d_sb->s_op->statfs \|\|
	134	!root->d_sb->s_op->sync_fs)
	135	goto error_unsupported;
	136
	137	ret = -EROFS;
	138	if (root->d_sb->s_flags & MS_RDONLY)
	139	goto error_unsupported;
	140
	141	/* determine the security of the on-disk cache as this governs
	142	* security ID of files we create */
	143	ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
	144	if (ret < 0)
	145	goto error_unsupported;
	146
	147	/* get the cache size and blocksize */
ebabe9a9	148	ret = vfs_statfs(&path, &stats);
9ae326a6 DH	149	if (ret < 0)
	150	goto error_unsupported;
	151
	152	ret = -ERANGE;
	153	if (stats.f_bsize <= 0)
	154	goto error_unsupported;
	155
	156	ret = -EOPNOTSUPP;
	157	if (stats.f_bsize > PAGE_SIZE)
	158	goto error_unsupported;
	159
	160	cache->bsize = stats.f_bsize;
	161	cache->bshift = 0;
	162	if (stats.f_bsize < PAGE_SIZE)
	163	cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);
	164
	165	_debug("blksize %u (shift %u)",
	166	cache->bsize, cache->bshift);
	167
	168	_debug("size %llu, avail %llu",
	169	(unsigned long long) stats.f_blocks,
	170	(unsigned long long) stats.f_bavail);
	171
	172	/* set up caching limits */
	173	do_div(stats.f_files, 100);
	174	cache->fstop = stats.f_files * cache->fstop_percent;
	175	cache->fcull = stats.f_files * cache->fcull_percent;
	176	cache->frun = stats.f_files * cache->frun_percent;
	177
	178	_debug("limits {%llu,%llu,%llu} files",
	179	(unsigned long long) cache->frun,
	180	(unsigned long long) cache->fcull,
	181	(unsigned long long) cache->fstop);
	182
	183	stats.f_blocks >>= cache->bshift;
	184	do_div(stats.f_blocks, 100);
	185	cache->bstop = stats.f_blocks * cache->bstop_percent;
	186	cache->bcull = stats.f_blocks * cache->bcull_percent;
	187	cache->brun = stats.f_blocks * cache->brun_percent;
	188
	189	_debug("limits {%llu,%llu,%llu} blocks",
	190	(unsigned long long) cache->brun,
	191	(unsigned long long) cache->bcull,
	192	(unsigned long long) cache->bstop);
	193
	194	/* get the cache directory and check its type */
	195	cachedir = cachefiles_get_directory(cache, root, "cache");
	196	if (IS_ERR(cachedir)) {
	197	ret = PTR_ERR(cachedir);
	198	goto error_unsupported;
	199	}
	200
	201	fsdef->dentry = cachedir;
	202	fsdef->fscache.cookie = NULL;
	203
	204	ret = cachefiles_check_object_type(fsdef);
	205	if (ret < 0)
	206	goto error_unsupported;
	207
	208	/* get the graveyard directory */
	209	graveyard = cachefiles_get_directory(cache, root, "graveyard");
	210	if (IS_ERR(graveyard)) {
	211	ret = PTR_ERR(graveyard);
	212	goto error_unsupported;
213	}
214
215	cache->graveyard = graveyard;
216
217	/* publish the cache */
218	fscache_init_cache(&cache->cache,
219	&cachefiles_cache_ops,
220	"%s",
221	fsdef->dentry->d_sb->s_id);
222
223	fscache_object_init(&fsdef->fscache, NULL, &cache->cache);
224
225	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
226	if (ret < 0)
227	goto error_add_cache;
228
229	/* done */
230	set_bit(CACHEFILES_READY, &cache->flags);
231	dput(root);
232
233	printk(KERN_INFO "CacheFiles:"
234	" File cache on %s registered\n",
235	cache->cache.identifier);
236
237	/* check how much space the cache has */
238	cachefiles_has_space(cache, 0, 0);
239	cachefiles_end_secure(cache, saved_cred);
240	return 0;
241
242	error_add_cache:
243	dput(cache->graveyard);
244	cache->graveyard = NULL;
245	error_unsupported:
246	mntput(cache->mnt);
247	cache->mnt = NULL;
248	dput(fsdef->dentry);
249	fsdef->dentry = NULL;
250	dput(root);
251	error_open_root:
252	kmem_cache_free(cachefiles_object_jar, fsdef);
253	error_root_object:
254	cachefiles_end_secure(cache, saved_cred);
255	kerror("Failed to register: %d", ret);
256	return ret;
257	}
258
259	/*
260	* unbind a cache on fd release
261	*/
262	void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
263	{
264	_enter("");
265
266	if (test_bit(CACHEFILES_READY, &cache->flags)) {
267	printk(KERN_INFO "CacheFiles:"
268	" File cache on %s unregistering\n",
269	cache->cache.identifier);
270
271	fscache_withdraw_cache(&cache->cache);
272	}
273
274	dput(cache->graveyard);
275	mntput(cache->mnt);
276
277	kfree(cache->rootdirname);
278	kfree(cache->secctx);
279	kfree(cache->tag);
280
281	_leave("");
282	}