[linux-2.6-block.git] / fs / cachefiles / bind.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* 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)
 */

#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
b4d0d230	1	// SPDX-License-Identifier: GPL-2.0-or-later
9ae326a6 DH	2	/* Bind and unbind a cache from the filesystem backing it
	3	*
	4	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	5	* Written by David Howells (dhowells@redhat.com)
9ae326a6 DH	6	*/
	7
	8	#include <linux/module.h>
	9	#include <linux/init.h>
	10	#include <linux/sched.h>
	11	#include <linux/completion.h>
	12	#include <linux/slab.h>
	13	#include <linux/fs.h>
	14	#include <linux/file.h>
	15	#include <linux/namei.h>
	16	#include <linux/mount.h>
	17	#include <linux/statfs.h>
	18	#include <linux/ctype.h>
5d6c3191	19	#include <linux/xattr.h>
9ae326a6 DH	20	#include "internal.h"
	21
	22	static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);
	23
	24	/*
	25	* bind a directory as a cache
	26	*/
	27	int cachefiles_daemon_bind(struct cachefiles_cache cache, char args)
	28	{
	29	_enter("{%u,%u,%u,%u,%u,%u},%s",
	30	cache->frun_percent,
	31	cache->fcull_percent,
	32	cache->fstop_percent,
	33	cache->brun_percent,
	34	cache->bcull_percent,
	35	cache->bstop_percent,
	36	args);
	37
	38	/* start by checking things over */
	39	ASSERT(cache->fstop_percent >= 0 &&
	40	cache->fstop_percent < cache->fcull_percent &&
	41	cache->fcull_percent < cache->frun_percent &&
	42	cache->frun_percent < 100);
	43
	44	ASSERT(cache->bstop_percent >= 0 &&
	45	cache->bstop_percent < cache->bcull_percent &&
	46	cache->bcull_percent < cache->brun_percent &&
	47	cache->brun_percent < 100);
	48
	49	if (*args) {
6ff66ac7	50	pr_err("'bind' command doesn't take an argument\n");
9ae326a6 DH	51	return -EINVAL;
	52	}
	53
	54	if (!cache->rootdirname) {
6ff66ac7	55	pr_err("No cache directory specified\n");
9ae326a6 DH	56	return -EINVAL;
	57	}
	58
	59	/* don't permit already bound caches to be re-bound */
	60	if (test_bit(CACHEFILES_READY, &cache->flags)) {
6ff66ac7	61	pr_err("Cache already bound\n");
9ae326a6 DH	62	return -EBUSY;
	63	}
	64
	65	/* make sure we have copies of the tag and dirname strings */
	66	if (!cache->tag) {
	67	/* the tag string is released by the fops->release()
	68	* function, so we don't release it on error here */
	69	cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
	70	if (!cache->tag)
	71	return -ENOMEM;
	72	}
	73
	74	/* add the cache */
	75	return cachefiles_daemon_add_cache(cache);
	76	}
	77
	78	/*
	79	* add a cache
	80	*/
	81	static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
	82	{
	83	struct cachefiles_object *fsdef;
b0446be4	84	struct path path;
9ae326a6 DH	85	struct kstatfs stats;
	86	struct dentry graveyard, cachedir, *root;
	87	const struct cred *saved_cred;
	88	int ret;
	89
	90	_enter("");
	91
	92	/* we want to work under the module's security ID */
	93	ret = cachefiles_get_security_ID(cache);
	94	if (ret < 0)
	95	return ret;
	96
	97	cachefiles_begin_secure(cache, &saved_cred);
	98
	99	/* allocate the root index object */
	100	ret = -ENOMEM;
	101
	102	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
	103	if (!fsdef)
	104	goto error_root_object;
	105
	106	ASSERTCMP(fsdef->backer, ==, NULL);
	107
	108	atomic_set(&fsdef->usage, 1);
	109	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;
	110
	111	_debug("- fsdef %p", fsdef);
	112
	113	/* look up the directory at the root of the cache */
b0446be4	114	ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
9ae326a6 DH	115	if (ret < 0)
	116	goto error_open_root;
	117
b0446be4 AV	118	cache->mnt = path.mnt;
b0446be4 AV	119	root = path.dentry;
9ae326a6 DH	120
	121	/* check parameters */
	122	ret = -EOPNOTSUPP;
466b77bc DH	123	if (d_is_negative(root) \|\|
	124	!d_backing_inode(root)->i_op->lookup \|\|
	125	!d_backing_inode(root)->i_op->mkdir \|\|
5d6c3191	126	!(d_backing_inode(root)->i_opflags & IOP_XATTR) \|\|
9ae326a6 DH	127	!root->d_sb->s_op->statfs \|\|
	128	!root->d_sb->s_op->sync_fs)
	129	goto error_unsupported;
	130
	131	ret = -EROFS;
bc98a42c	132	if (sb_rdonly(root->d_sb))
9ae326a6 DH	133	goto error_unsupported;
	134
	135	/* determine the security of the on-disk cache as this governs
	136	* security ID of files we create */
	137	ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
	138	if (ret < 0)
	139	goto error_unsupported;
	140
	141	/* get the cache size and blocksize */
ebabe9a9	142	ret = vfs_statfs(&path, &stats);
9ae326a6 DH	143	if (ret < 0)
	144	goto error_unsupported;
	145
	146	ret = -ERANGE;
	147	if (stats.f_bsize <= 0)
	148	goto error_unsupported;
	149
	150	ret = -EOPNOTSUPP;
	151	if (stats.f_bsize > PAGE_SIZE)
	152	goto error_unsupported;
	153
	154	cache->bsize = stats.f_bsize;
	155	cache->bshift = 0;
	156	if (stats.f_bsize < PAGE_SIZE)
	157	cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);
	158
	159	_debug("blksize %u (shift %u)",
	160	cache->bsize, cache->bshift);
	161
	162	_debug("size %llu, avail %llu",
	163	(unsigned long long) stats.f_blocks,
	164	(unsigned long long) stats.f_bavail);
	165
	166	/* set up caching limits */
	167	do_div(stats.f_files, 100);
	168	cache->fstop = stats.f_files * cache->fstop_percent;
	169	cache->fcull = stats.f_files * cache->fcull_percent;
	170	cache->frun = stats.f_files * cache->frun_percent;
	171
	172	_debug("limits {%llu,%llu,%llu} files",
	173	(unsigned long long) cache->frun,
	174	(unsigned long long) cache->fcull,
	175	(unsigned long long) cache->fstop);
	176
	177	stats.f_blocks >>= cache->bshift;
	178	do_div(stats.f_blocks, 100);
	179	cache->bstop = stats.f_blocks * cache->bstop_percent;
	180	cache->bcull = stats.f_blocks * cache->bcull_percent;
	181	cache->brun = stats.f_blocks * cache->brun_percent;
	182
	183	_debug("limits {%llu,%llu,%llu} blocks",
	184	(unsigned long long) cache->brun,
	185	(unsigned long long) cache->bcull,
	186	(unsigned long long) cache->bstop);
	187
	188	/* get the cache directory and check its type */
	189	cachedir = cachefiles_get_directory(cache, root, "cache");
	190	if (IS_ERR(cachedir)) {
	191	ret = PTR_ERR(cachedir);
	192	goto error_unsupported;
	193	}
	194
	195	fsdef->dentry = cachedir;
	196	fsdef->fscache.cookie = NULL;
	197
	198	ret = cachefiles_check_object_type(fsdef);
	199	if (ret < 0)
	200	goto error_unsupported;
	201
	202	/* get the graveyard directory */
	203	graveyard = cachefiles_get_directory(cache, root, "graveyard");
	204	if (IS_ERR(graveyard)) {
	205	ret = PTR_ERR(graveyard);
	206	goto error_unsupported;
207	}
208
209	cache->graveyard = graveyard;
210
211	/* publish the cache */
212	fscache_init_cache(&cache->cache,
213	&cachefiles_cache_ops,
214	"%s",
215	fsdef->dentry->d_sb->s_id);
216
f29507ce KKM	217	fscache_object_init(&fsdef->fscache, &fscache_fsdef_index,
f29507ce KKM	218	&cache->cache);
9ae326a6 DH	219
	220	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
	221	if (ret < 0)
	222	goto error_add_cache;
	223
	224	/* done */
	225	set_bit(CACHEFILES_READY, &cache->flags);
	226	dput(root);
	227
0227d6ab	228	pr_info("File cache on %s registered\n", cache->cache.identifier);
9ae326a6 DH	229
	230	/* check how much space the cache has */
	231	cachefiles_has_space(cache, 0, 0);
	232	cachefiles_end_secure(cache, saved_cred);
	233	return 0;
	234
	235	error_add_cache:
	236	dput(cache->graveyard);
	237	cache->graveyard = NULL;
	238	error_unsupported:
	239	mntput(cache->mnt);
	240	cache->mnt = NULL;
	241	dput(fsdef->dentry);
	242	fsdef->dentry = NULL;
	243	dput(root);
	244	error_open_root:
	245	kmem_cache_free(cachefiles_object_jar, fsdef);
	246	error_root_object:
	247	cachefiles_end_secure(cache, saved_cred);
6ff66ac7	248	pr_err("Failed to register: %d\n", ret);
9ae326a6 DH	249	return ret;
	250	}
	251
	252	/*
	253	* unbind a cache on fd release
	254	*/
	255	void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
	256	{
	257	_enter("");
	258
	259	if (test_bit(CACHEFILES_READY, &cache->flags)) {
0227d6ab	260	pr_info("File cache on %s unregistering\n",
4e1eb883	261	cache->cache.identifier);
9ae326a6 DH	262
	263	fscache_withdraw_cache(&cache->cache);
	264	}
	265
	266	dput(cache->graveyard);
	267	mntput(cache->mnt);
	268
	269	kfree(cache->rootdirname);
	270	kfree(cache->secctx);
	271	kfree(cache->tag);
	272
	273	_leave("");
	274	}