[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 ([email protected])
 *
 * 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 <linux/xattr.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) {
		pr_err("'bind' command doesn't take an argument\n");
		return -EINVAL;
	}

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

	/* don't permit already bound caches to be re-bound */
	if (test_bit(CACHEFILES_READY, &cache->flags)) {
		pr_err("Cache already bound\n");
		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 (d_is_negative(root) ||
	    !d_backing_inode(root)->i_op->lookup ||
	    !d_backing_inode(root)->i_op->mkdir ||
	    !(d_backing_inode(root)->i_opflags & IOP_XATTR) ||
	    !root->d_sb->s_op->statfs ||
	    !root->d_sb->s_op->sync_fs)
		goto error_unsupported;

	ret = -EROFS;
	if (sb_rdonly(root->d_sb))
		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, &fscache_fsdef_index,
			    &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);

	pr_info("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);
	pr_err("Failed to register: %d\n", 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)) {
		pr_info("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 ([email protected])
	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>
5d6c3191	23	#include <linux/xattr.h>
9ae326a6 DH	24	#include "internal.h"
	25
	26	static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
	27
	28	/*
	29	* bind a directory as a cache
	30	*/
	31	int cachefiles_daemon_bind(struct cachefiles_cache cache, char args)
	32	{
	33	_enter("{%u,%u,%u,%u,%u,%u},%s",
	34	cache->frun_percent,
	35	cache->fcull_percent,
	36	cache->fstop_percent,
	37	cache->brun_percent,
	38	cache->bcull_percent,
	39	cache->bstop_percent,
	40	args);
	41
	42	/* start by checking things over */
	43	ASSERT(cache->fstop_percent >= 0 &&
	44	cache->fstop_percent < cache->fcull_percent &&
	45	cache->fcull_percent < cache->frun_percent &&
	46	cache->frun_percent < 100);
	47
	48	ASSERT(cache->bstop_percent >= 0 &&
	49	cache->bstop_percent < cache->bcull_percent &&
	50	cache->bcull_percent < cache->brun_percent &&
	51	cache->brun_percent < 100);
	52
	53	if (*args) {
6ff66ac7	54	pr_err("'bind' command doesn't take an argument\n");
9ae326a6 DH	55	return -EINVAL;
	56	}
	57
	58	if (!cache->rootdirname) {
6ff66ac7	59	pr_err("No cache directory specified\n");
9ae326a6 DH	60	return -EINVAL;
	61	}
	62
	63	/* don't permit already bound caches to be re-bound */
	64	if (test_bit(CACHEFILES_READY, &cache->flags)) {
6ff66ac7	65	pr_err("Cache already bound\n");
9ae326a6 DH	66	return -EBUSY;
	67	}
	68
	69	/* make sure we have copies of the tag and dirname strings */
	70	if (!cache->tag) {
	71	/* the tag string is released by the fops->release()
	72	* function, so we don't release it on error here */
	73	cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
	74	if (!cache->tag)
	75	return -ENOMEM;
	76	}
	77
	78	/* add the cache */
	79	return cachefiles_daemon_add_cache(cache);
	80	}
	81
	82	/*
	83	* add a cache
	84	*/
	85	static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
	86	{
	87	struct cachefiles_object *fsdef;
b0446be4	88	struct path path;
9ae326a6 DH	89	struct kstatfs stats;
	90	struct dentry graveyard, cachedir, *root;
	91	const struct cred *saved_cred;
	92	int ret;
	93
	94	_enter("");
	95
	96	/* we want to work under the module's security ID */
	97	ret = cachefiles_get_security_ID(cache);
	98	if (ret < 0)
	99	return ret;
	100
	101	cachefiles_begin_secure(cache, &saved_cred);
	102
	103	/* allocate the root index object */
	104	ret = -ENOMEM;
	105
	106	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
	107	if (!fsdef)
	108	goto error_root_object;
	109
	110	ASSERTCMP(fsdef->backer, ==, NULL);
	111
	112	atomic_set(&fsdef->usage, 1);
	113	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;
	114
	115	_debug("- fsdef %p", fsdef);
	116
	117	/* look up the directory at the root of the cache */
b0446be4	118	ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
9ae326a6 DH	119	if (ret < 0)
	120	goto error_open_root;
	121
b0446be4 AV	122	cache->mnt = path.mnt;
b0446be4 AV	123	root = path.dentry;
9ae326a6 DH	124
	125	/* check parameters */
	126	ret = -EOPNOTSUPP;
466b77bc DH	127	if (d_is_negative(root) \|\|
	128	!d_backing_inode(root)->i_op->lookup \|\|
	129	!d_backing_inode(root)->i_op->mkdir \|\|
5d6c3191	130	!(d_backing_inode(root)->i_opflags & IOP_XATTR) \|\|
9ae326a6 DH	131	!root->d_sb->s_op->statfs \|\|
	132	!root->d_sb->s_op->sync_fs)
	133	goto error_unsupported;
	134
	135	ret = -EROFS;
bc98a42c	136	if (sb_rdonly(root->d_sb))
9ae326a6 DH	137	goto error_unsupported;
	138
	139	/* determine the security of the on-disk cache as this governs
	140	* security ID of files we create */
	141	ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
	142	if (ret < 0)
	143	goto error_unsupported;
	144
	145	/* get the cache size and blocksize */
ebabe9a9	146	ret = vfs_statfs(&path, &stats);
9ae326a6 DH	147	if (ret < 0)
	148	goto error_unsupported;
	149
	150	ret = -ERANGE;
	151	if (stats.f_bsize <= 0)
	152	goto error_unsupported;
	153
	154	ret = -EOPNOTSUPP;
	155	if (stats.f_bsize > PAGE_SIZE)
	156	goto error_unsupported;
	157
	158	cache->bsize = stats.f_bsize;
	159	cache->bshift = 0;
	160	if (stats.f_bsize < PAGE_SIZE)
	161	cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);
	162
	163	_debug("blksize %u (shift %u)",
	164	cache->bsize, cache->bshift);
	165
	166	_debug("size %llu, avail %llu",
	167	(unsigned long long) stats.f_blocks,
	168	(unsigned long long) stats.f_bavail);
	169
	170	/* set up caching limits */
	171	do_div(stats.f_files, 100);
	172	cache->fstop = stats.f_files * cache->fstop_percent;
	173	cache->fcull = stats.f_files * cache->fcull_percent;
	174	cache->frun = stats.f_files * cache->frun_percent;
	175
	176	_debug("limits {%llu,%llu,%llu} files",
	177	(unsigned long long) cache->frun,
	178	(unsigned long long) cache->fcull,
	179	(unsigned long long) cache->fstop);
	180
	181	stats.f_blocks >>= cache->bshift;
	182	do_div(stats.f_blocks, 100);
	183	cache->bstop = stats.f_blocks * cache->bstop_percent;
	184	cache->bcull = stats.f_blocks * cache->bcull_percent;
	185	cache->brun = stats.f_blocks * cache->brun_percent;
	186
	187	_debug("limits {%llu,%llu,%llu} blocks",
	188	(unsigned long long) cache->brun,
	189	(unsigned long long) cache->bcull,
	190	(unsigned long long) cache->bstop);
	191
	192	/* get the cache directory and check its type */
	193	cachedir = cachefiles_get_directory(cache, root, "cache");
	194	if (IS_ERR(cachedir)) {
	195	ret = PTR_ERR(cachedir);
	196	goto error_unsupported;
	197	}
	198
	199	fsdef->dentry = cachedir;
	200	fsdef->fscache.cookie = NULL;
	201
	202	ret = cachefiles_check_object_type(fsdef);
	203	if (ret < 0)
	204	goto error_unsupported;
	205
	206	/* get the graveyard directory */
	207	graveyard = cachefiles_get_directory(cache, root, "graveyard");
	208	if (IS_ERR(graveyard)) {
	209	ret = PTR_ERR(graveyard);
	210	goto error_unsupported;
211	}
212
213	cache->graveyard = graveyard;
214
215	/* publish the cache */
216	fscache_init_cache(&cache->cache,
217	&cachefiles_cache_ops,
218	"%s",
219	fsdef->dentry->d_sb->s_id);
220
f29507ce KKM	221	fscache_object_init(&fsdef->fscache, &fscache_fsdef_index,
f29507ce KKM	222	&cache->cache);
9ae326a6 DH	223
	224	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
	225	if (ret < 0)
	226	goto error_add_cache;
	227
	228	/* done */
	229	set_bit(CACHEFILES_READY, &cache->flags);
	230	dput(root);
	231
0227d6ab	232	pr_info("File cache on %s registered\n", cache->cache.identifier);
9ae326a6 DH	233
	234	/* check how much space the cache has */
	235	cachefiles_has_space(cache, 0, 0);
	236	cachefiles_end_secure(cache, saved_cred);
	237	return 0;
	238
	239	error_add_cache:
	240	dput(cache->graveyard);
	241	cache->graveyard = NULL;
	242	error_unsupported:
	243	mntput(cache->mnt);
	244	cache->mnt = NULL;
	245	dput(fsdef->dentry);
	246	fsdef->dentry = NULL;
	247	dput(root);
	248	error_open_root:
	249	kmem_cache_free(cachefiles_object_jar, fsdef);
	250	error_root_object:
	251	cachefiles_end_secure(cache, saved_cred);
6ff66ac7	252	pr_err("Failed to register: %d\n", ret);
9ae326a6 DH	253	return ret;
	254	}
	255
	256	/*
	257	* unbind a cache on fd release
	258	*/
	259	void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
	260	{
	261	_enter("");
	262
	263	if (test_bit(CACHEFILES_READY, &cache->flags)) {
0227d6ab	264	pr_info("File cache on %s unregistering\n",
4e1eb883	265	cache->cache.identifier);
9ae326a6 DH	266
	267	fscache_withdraw_cache(&cache->cache);
	268	}
	269
	270	dput(cache->graveyard);
	271	mntput(cache->mnt);
	272
	273	kfree(cache->rootdirname);
	274	kfree(cache->secctx);
	275	kfree(cache->tag);
	276
	277	_leave("");
	278	}