4 * Copyright (c) 2013 Samsung Electronics Co. Ltd
5 * Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
6 * Sunghwan Yun, Sungjong Seo
8 * This program has been developed as a stackable file system based on
9 * the WrapFS which written by
11 * Copyright (c) 1998-2011 Erez Zadok
12 * Copyright (c) 2009 Shrikar Archak
13 * Copyright (c) 2003-2011 Stony Brook University
14 * Copyright (c) 2003-2011 The Research Foundation of SUNY
16 * This file is dual licensed. It may be redistributed and/or modified
17 * under the terms of the Apache 2.0 License OR version 2 of the GNU
18 * General Public License.
22 #include <linux/module.h>
23 #include <linux/types.h>
24 #include <linux/parser.h>
33 Opt_multiuser, // May need?
39 static const match_table_t sdcardfs_tokens = {
40 {Opt_fsuid, "fsuid=%u"},
41 {Opt_fsgid, "fsgid=%u"},
44 {Opt_lower_fs, "lower_fs=%s"},
45 {Opt_mask, "mask=%u"},
46 {Opt_userid, "userid=%d"},
47 {Opt_multiuser, "multiuser"},
48 {Opt_reserved_mb, "reserved_mb=%u"},
52 static int parse_options(struct super_block *sb, char *options, int silent,
53 int *debug, struct sdcardfs_mount_options *opts)
56 substring_t args[MAX_OPT_ARGS];
60 /* by default, we use AID_MEDIA_RW as uid, gid */
61 opts->fs_low_uid = AID_MEDIA_RW;
62 opts->fs_low_gid = AID_MEDIA_RW;
64 opts->multiuser = false;
67 /* by default, we use LOWER_FS_EXT4 as lower fs type */
68 opts->lower_fs = LOWER_FS_EXT4;
69 /* by default, 0MB is reserved */
70 opts->reserved_mb = 0;
77 while ((p = strsep(&options, ",")) != NULL) {
82 token = match_token(p, sdcardfs_tokens, args);
89 if (match_int(&args[0], &option))
91 opts->fs_low_uid = option;
94 if (match_int(&args[0], &option))
96 opts->fs_low_gid = option;
99 if (match_int(&args[0], &option))
104 if (match_int(&args[0], &option))
106 opts->fs_user_id = option;
109 if (match_int(&args[0], &option))
114 opts->multiuser = true;
117 string_option = match_strdup(&args[0]);
118 if (!strcmp("ext4", string_option)) {
119 opts->lower_fs = LOWER_FS_EXT4;
120 } else if (!strcmp("fat", string_option)) {
121 opts->lower_fs = LOWER_FS_FAT;
123 kfree(string_option);
126 kfree(string_option);
128 case Opt_reserved_mb:
129 if (match_int(&args[0], &option))
131 opts->reserved_mb = option;
137 printk( KERN_ERR "Unrecognized mount option \"%s\" "
138 "or missing value", p);
145 printk( KERN_INFO "sdcardfs : options - debug:%d\n", *debug);
146 printk( KERN_INFO "sdcardfs : options - uid:%d\n",
148 printk( KERN_INFO "sdcardfs : options - gid:%d\n",
157 * our custom d_alloc_root work-alike
159 * we can't use d_alloc_root if we want to use our own interpose function
160 * unchanged, so we simply call our own "fake" d_alloc_root
162 static struct dentry *sdcardfs_d_alloc_root(struct super_block *sb)
164 struct dentry *ret = NULL;
167 static const struct qstr name = {
172 ret = d_alloc(NULL, &name);
174 d_set_d_op(ret, &sdcardfs_ci_dops);
183 DEFINE_MUTEX(sdcardfs_super_list_lock);
184 LIST_HEAD(sdcardfs_super_list);
185 EXPORT_SYMBOL_GPL(sdcardfs_super_list_lock);
186 EXPORT_SYMBOL_GPL(sdcardfs_super_list);
189 * There is no need to lock the sdcardfs_super_info's rwsem as there is no
190 * way anyone can have a reference to the superblock at this point in time.
192 static int sdcardfs_read_super(struct super_block *sb, const char *dev_name,
193 void *raw_data, int silent)
197 struct super_block *lower_sb;
198 struct path lower_path;
199 struct sdcardfs_sb_info *sb_info;
202 printk(KERN_INFO "sdcardfs version 2.0\n");
206 "sdcardfs: read_super: missing dev_name argument\n");
211 printk(KERN_INFO "sdcardfs: dev_name -> %s\n", dev_name);
212 printk(KERN_INFO "sdcardfs: options -> %s\n", (char *)raw_data);
214 /* parse lower path */
215 err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
218 printk(KERN_ERR "sdcardfs: error accessing lower directory '%s'\n", dev_name);
222 /* allocate superblock private data */
223 sb->s_fs_info = kzalloc(sizeof(struct sdcardfs_sb_info), GFP_KERNEL);
224 if (!SDCARDFS_SB(sb)) {
225 printk(KERN_CRIT "sdcardfs: read_super: out of memory\n");
230 sb_info = sb->s_fs_info;
232 err = parse_options(sb, raw_data, silent, &debug, &sb_info->options);
234 printk(KERN_ERR "sdcardfs: invalid options\n");
238 /* set the lower superblock field of upper superblock */
239 lower_sb = lower_path.dentry->d_sb;
240 atomic_inc(&lower_sb->s_active);
241 sdcardfs_set_lower_super(sb, lower_sb);
243 /* inherit maxbytes from lower file system */
244 sb->s_maxbytes = lower_sb->s_maxbytes;
247 * Our c/m/atime granularity is 1 ns because we may stack on file
248 * systems whose granularity is as good.
252 sb->s_magic = SDCARDFS_SUPER_MAGIC;
253 sb->s_op = &sdcardfs_sops;
255 /* get a new inode and allocate our root dentry */
256 inode = sdcardfs_iget(sb, lower_path.dentry->d_inode, 0);
258 err = PTR_ERR(inode);
261 sb->s_root = d_make_root(inode);
266 d_set_d_op(sb->s_root, &sdcardfs_ci_dops);
268 /* link the upper and lower dentries */
269 sb->s_root->d_fsdata = NULL;
270 err = new_dentry_private_data(sb->s_root);
274 /* set the lower dentries for s_root */
275 sdcardfs_set_lower_path(sb->s_root, &lower_path);
278 * No need to call interpose because we already have a positive
279 * dentry, which was instantiated by d_make_root. Just need to
282 d_rehash(sb->s_root);
284 /* setup permission policy */
285 sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
286 mutex_lock(&sdcardfs_super_list_lock);
287 if(sb_info->options.multiuser) {
288 setup_derived_state(sb->s_root->d_inode, PERM_PRE_ROOT, sb_info->options.fs_user_id, AID_ROOT, false);
289 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
290 /*err = prepare_dir(sb_info->obbpath_s,
291 sb_info->options.fs_low_uid,
292 sb_info->options.fs_low_gid, 00755);*/
294 setup_derived_state(sb->s_root->d_inode, PERM_ROOT, sb_info->options.fs_low_uid, AID_ROOT, false);
295 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
297 fix_derived_permission(sb->s_root->d_inode);
299 list_add(&sb_info->list, &sdcardfs_super_list);
300 mutex_unlock(&sdcardfs_super_list_lock);
303 printk(KERN_INFO "sdcardfs: mounted on top of %s type %s\n",
304 dev_name, lower_sb->s_type->name);
305 goto out; /* all is well */
307 /* no longer needed: free_dentry_private_data(sb->s_root); */
313 /* drop refs we took earlier */
314 atomic_dec(&lower_sb->s_active);
316 kfree(SDCARDFS_SB(sb));
317 sb->s_fs_info = NULL;
319 path_put(&lower_path);
325 /* A feature which supports mount_nodev() with options */
326 static struct dentry *mount_nodev_with_options(struct file_system_type *fs_type,
327 int flags, const char *dev_name, void *data,
328 int (*fill_super)(struct super_block *, const char *, void *, int))
332 struct super_block *s = sget(fs_type, NULL, set_anon_super, flags, NULL);
339 error = fill_super(s, dev_name, data, flags & MS_SILENT ? 1 : 0);
341 deactivate_locked_super(s);
342 return ERR_PTR(error);
344 s->s_flags |= MS_ACTIVE;
345 return dget(s->s_root);
348 struct dentry *sdcardfs_mount(struct file_system_type *fs_type, int flags,
349 const char *dev_name, void *raw_data)
352 * dev_name is a lower_path_name,
353 * raw_data is a option string.
355 return mount_nodev_with_options(fs_type, flags, dev_name,
356 raw_data, sdcardfs_read_super);
359 void sdcardfs_kill_sb(struct super_block *sb) {
360 struct sdcardfs_sb_info *sbi;
361 if (sb->s_magic == SDCARDFS_SUPER_MAGIC) {
362 sbi = SDCARDFS_SB(sb);
363 mutex_lock(&sdcardfs_super_list_lock);
364 list_del(&sbi->list);
365 mutex_unlock(&sdcardfs_super_list_lock);
367 generic_shutdown_super(sb);
370 static struct file_system_type sdcardfs_fs_type = {
371 .owner = THIS_MODULE,
372 .name = SDCARDFS_NAME,
373 .mount = sdcardfs_mount,
374 .kill_sb = sdcardfs_kill_sb,
378 static int __init init_sdcardfs_fs(void)
382 pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
384 err = sdcardfs_init_inode_cache();
387 err = sdcardfs_init_dentry_cache();
390 err = packagelist_init();
393 err = register_filesystem(&sdcardfs_fs_type);
396 sdcardfs_destroy_inode_cache();
397 sdcardfs_destroy_dentry_cache();
403 static void __exit exit_sdcardfs_fs(void)
405 sdcardfs_destroy_inode_cache();
406 sdcardfs_destroy_dentry_cache();
408 unregister_filesystem(&sdcardfs_fs_type);
409 pr_info("Completed sdcardfs module unload\n");
412 MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
413 " (http://www.fsl.cs.sunysb.edu/)");
414 MODULE_DESCRIPTION("Wrapfs " SDCARDFS_VERSION
415 " (http://wrapfs.filesystems.org/)");
416 MODULE_LICENSE("GPL");
418 module_init(init_sdcardfs_fs);
419 module_exit(exit_sdcardfs_fs);