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1da177e4 LT |
1 | /* |
2 | * Resizable simple ram filesystem for Linux. | |
3 | * | |
4 | * Copyright (C) 2000 Linus Torvalds. | |
5 | * 2000 Transmeta Corp. | |
6 | * | |
7 | * Usage limits added by David Gibson, Linuxcare Australia. | |
8 | * This file is released under the GPL. | |
9 | */ | |
10 | ||
11 | /* | |
12 | * NOTE! This filesystem is probably most useful | |
13 | * not as a real filesystem, but as an example of | |
14 | * how virtual filesystems can be written. | |
15 | * | |
16 | * It doesn't get much simpler than this. Consider | |
17 | * that this file implements the full semantics of | |
18 | * a POSIX-compliant read-write filesystem. | |
19 | * | |
20 | * Note in particular how the filesystem does not | |
21 | * need to implement any data structures of its own | |
22 | * to keep track of the virtual data: using the VFS | |
23 | * caches is sufficient. | |
24 | */ | |
25 | ||
26 | #include <linux/module.h> | |
27 | #include <linux/fs.h> | |
28 | #include <linux/pagemap.h> | |
29 | #include <linux/highmem.h> | |
8dde0509 | 30 | #include <linux/time.h> |
1da177e4 LT |
31 | #include <linux/init.h> |
32 | #include <linux/string.h> | |
1da177e4 LT |
33 | #include <linux/backing-dev.h> |
34 | #include <linux/ramfs.h> | |
e8edc6e0 | 35 | #include <linux/sched.h> |
c3b1b1cb | 36 | #include <linux/parser.h> |
a7e3108c | 37 | #include <linux/magic.h> |
1da177e4 | 38 | #include <asm/uaccess.h> |
642fb4d1 | 39 | #include "internal.h" |
1da177e4 | 40 | |
c3b1b1cb WF |
41 | #define RAMFS_DEFAULT_MODE 0755 |
42 | ||
ee9b6d61 | 43 | static const struct super_operations ramfs_ops; |
c5ef1c42 | 44 | static const struct inode_operations ramfs_dir_inode_operations; |
1da177e4 LT |
45 | |
46 | static struct backing_dev_info ramfs_backing_dev_info = { | |
d993831f | 47 | .name = "ramfs", |
1da177e4 | 48 | .ra_pages = 0, /* No readahead */ |
e4ad08fe | 49 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | |
1da177e4 LT |
50 | BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY | |
51 | BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP, | |
52 | }; | |
53 | ||
54 | struct inode *ramfs_get_inode(struct super_block *sb, int mode, dev_t dev) | |
55 | { | |
56 | struct inode * inode = new_inode(sb); | |
57 | ||
58 | if (inode) { | |
59 | inode->i_mode = mode; | |
0785f4da DH |
60 | inode->i_uid = current_fsuid(); |
61 | inode->i_gid = current_fsgid(); | |
1da177e4 LT |
62 | inode->i_mapping->a_ops = &ramfs_aops; |
63 | inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info; | |
769848c0 | 64 | mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER); |
ba9ddf49 | 65 | mapping_set_unevictable(inode->i_mapping); |
1da177e4 LT |
66 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
67 | switch (mode & S_IFMT) { | |
68 | default: | |
69 | init_special_inode(inode, mode, dev); | |
70 | break; | |
71 | case S_IFREG: | |
72 | inode->i_op = &ramfs_file_inode_operations; | |
73 | inode->i_fop = &ramfs_file_operations; | |
74 | break; | |
75 | case S_IFDIR: | |
76 | inode->i_op = &ramfs_dir_inode_operations; | |
77 | inode->i_fop = &simple_dir_operations; | |
78 | ||
79 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
d8c76e6f | 80 | inc_nlink(inode); |
1da177e4 LT |
81 | break; |
82 | case S_IFLNK: | |
83 | inode->i_op = &page_symlink_inode_operations; | |
84 | break; | |
85 | } | |
86 | } | |
87 | return inode; | |
88 | } | |
89 | ||
90 | /* | |
91 | * File creation. Allocate an inode, and we're done.. | |
92 | */ | |
93 | /* SMP-safe */ | |
94 | static int | |
95 | ramfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) | |
96 | { | |
97 | struct inode * inode = ramfs_get_inode(dir->i_sb, mode, dev); | |
98 | int error = -ENOSPC; | |
99 | ||
100 | if (inode) { | |
101 | if (dir->i_mode & S_ISGID) { | |
102 | inode->i_gid = dir->i_gid; | |
103 | if (S_ISDIR(mode)) | |
104 | inode->i_mode |= S_ISGID; | |
105 | } | |
106 | d_instantiate(dentry, inode); | |
107 | dget(dentry); /* Extra count - pin the dentry in core */ | |
108 | error = 0; | |
8dde0509 | 109 | dir->i_mtime = dir->i_ctime = CURRENT_TIME; |
1da177e4 LT |
110 | } |
111 | return error; | |
112 | } | |
113 | ||
114 | static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode) | |
115 | { | |
116 | int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0); | |
117 | if (!retval) | |
d8c76e6f | 118 | inc_nlink(dir); |
1da177e4 LT |
119 | return retval; |
120 | } | |
121 | ||
122 | static int ramfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd) | |
123 | { | |
124 | return ramfs_mknod(dir, dentry, mode | S_IFREG, 0); | |
125 | } | |
126 | ||
127 | static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname) | |
128 | { | |
129 | struct inode *inode; | |
130 | int error = -ENOSPC; | |
131 | ||
132 | inode = ramfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); | |
133 | if (inode) { | |
134 | int l = strlen(symname)+1; | |
135 | error = page_symlink(inode, symname, l); | |
136 | if (!error) { | |
137 | if (dir->i_mode & S_ISGID) | |
138 | inode->i_gid = dir->i_gid; | |
139 | d_instantiate(dentry, inode); | |
140 | dget(dentry); | |
ecbd3a63 | 141 | dir->i_mtime = dir->i_ctime = CURRENT_TIME; |
1da177e4 LT |
142 | } else |
143 | iput(inode); | |
144 | } | |
145 | return error; | |
146 | } | |
147 | ||
c5ef1c42 | 148 | static const struct inode_operations ramfs_dir_inode_operations = { |
1da177e4 LT |
149 | .create = ramfs_create, |
150 | .lookup = simple_lookup, | |
151 | .link = simple_link, | |
152 | .unlink = simple_unlink, | |
153 | .symlink = ramfs_symlink, | |
154 | .mkdir = ramfs_mkdir, | |
155 | .rmdir = simple_rmdir, | |
156 | .mknod = ramfs_mknod, | |
157 | .rename = simple_rename, | |
158 | }; | |
159 | ||
ee9b6d61 | 160 | static const struct super_operations ramfs_ops = { |
1da177e4 LT |
161 | .statfs = simple_statfs, |
162 | .drop_inode = generic_delete_inode, | |
c3b1b1cb WF |
163 | .show_options = generic_show_options, |
164 | }; | |
165 | ||
166 | struct ramfs_mount_opts { | |
167 | umode_t mode; | |
168 | }; | |
169 | ||
170 | enum { | |
171 | Opt_mode, | |
172 | Opt_err | |
173 | }; | |
174 | ||
175 | static const match_table_t tokens = { | |
176 | {Opt_mode, "mode=%o"}, | |
177 | {Opt_err, NULL} | |
178 | }; | |
179 | ||
180 | struct ramfs_fs_info { | |
181 | struct ramfs_mount_opts mount_opts; | |
1da177e4 LT |
182 | }; |
183 | ||
c3b1b1cb WF |
184 | static int ramfs_parse_options(char *data, struct ramfs_mount_opts *opts) |
185 | { | |
186 | substring_t args[MAX_OPT_ARGS]; | |
187 | int option; | |
188 | int token; | |
189 | char *p; | |
190 | ||
191 | opts->mode = RAMFS_DEFAULT_MODE; | |
192 | ||
193 | while ((p = strsep(&data, ",")) != NULL) { | |
194 | if (!*p) | |
195 | continue; | |
196 | ||
197 | token = match_token(p, tokens, args); | |
198 | switch (token) { | |
199 | case Opt_mode: | |
200 | if (match_octal(&args[0], &option)) | |
201 | return -EINVAL; | |
202 | opts->mode = option & S_IALLUGO; | |
203 | break; | |
0a8eba9b MF |
204 | /* |
205 | * We might like to report bad mount options here; | |
206 | * but traditionally ramfs has ignored all mount options, | |
207 | * and as it is used as a !CONFIG_SHMEM simple substitute | |
208 | * for tmpfs, better continue to ignore other mount options. | |
209 | */ | |
c3b1b1cb WF |
210 | } |
211 | } | |
212 | ||
213 | return 0; | |
214 | } | |
215 | ||
1da177e4 LT |
216 | static int ramfs_fill_super(struct super_block * sb, void * data, int silent) |
217 | { | |
c3b1b1cb WF |
218 | struct ramfs_fs_info *fsi; |
219 | struct inode *inode = NULL; | |
220 | struct dentry *root; | |
221 | int err; | |
222 | ||
223 | save_mount_options(sb, data); | |
224 | ||
225 | fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL); | |
f8201abc | 226 | sb->s_fs_info = fsi; |
c3b1b1cb WF |
227 | if (!fsi) { |
228 | err = -ENOMEM; | |
229 | goto fail; | |
230 | } | |
c3b1b1cb WF |
231 | |
232 | err = ramfs_parse_options(data, &fsi->mount_opts); | |
233 | if (err) | |
234 | goto fail; | |
1da177e4 | 235 | |
f8201abc IM |
236 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
237 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
238 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
239 | sb->s_magic = RAMFS_MAGIC; | |
240 | sb->s_op = &ramfs_ops; | |
241 | sb->s_time_gran = 1; | |
242 | ||
c3b1b1cb WF |
243 | inode = ramfs_get_inode(sb, S_IFDIR | fsi->mount_opts.mode, 0); |
244 | if (!inode) { | |
245 | err = -ENOMEM; | |
246 | goto fail; | |
247 | } | |
1da177e4 LT |
248 | |
249 | root = d_alloc_root(inode); | |
f8201abc | 250 | sb->s_root = root; |
1da177e4 | 251 | if (!root) { |
c3b1b1cb WF |
252 | err = -ENOMEM; |
253 | goto fail; | |
1da177e4 | 254 | } |
f8201abc | 255 | |
1da177e4 | 256 | return 0; |
c3b1b1cb WF |
257 | fail: |
258 | kfree(fsi); | |
f8201abc | 259 | sb->s_fs_info = NULL; |
c3b1b1cb WF |
260 | iput(inode); |
261 | return err; | |
1da177e4 LT |
262 | } |
263 | ||
454e2398 DH |
264 | int ramfs_get_sb(struct file_system_type *fs_type, |
265 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) | |
1da177e4 | 266 | { |
454e2398 | 267 | return get_sb_nodev(fs_type, flags, data, ramfs_fill_super, mnt); |
1da177e4 LT |
268 | } |
269 | ||
454e2398 DH |
270 | static int rootfs_get_sb(struct file_system_type *fs_type, |
271 | int flags, const char *dev_name, void *data, struct vfsmount *mnt) | |
1da177e4 | 272 | { |
454e2398 DH |
273 | return get_sb_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super, |
274 | mnt); | |
1da177e4 LT |
275 | } |
276 | ||
c3b1b1cb WF |
277 | static void ramfs_kill_sb(struct super_block *sb) |
278 | { | |
279 | kfree(sb->s_fs_info); | |
280 | kill_litter_super(sb); | |
281 | } | |
282 | ||
1da177e4 LT |
283 | static struct file_system_type ramfs_fs_type = { |
284 | .name = "ramfs", | |
285 | .get_sb = ramfs_get_sb, | |
c3b1b1cb | 286 | .kill_sb = ramfs_kill_sb, |
1da177e4 LT |
287 | }; |
288 | static struct file_system_type rootfs_fs_type = { | |
289 | .name = "rootfs", | |
290 | .get_sb = rootfs_get_sb, | |
291 | .kill_sb = kill_litter_super, | |
292 | }; | |
293 | ||
294 | static int __init init_ramfs_fs(void) | |
295 | { | |
296 | return register_filesystem(&ramfs_fs_type); | |
297 | } | |
298 | ||
299 | static void __exit exit_ramfs_fs(void) | |
300 | { | |
301 | unregister_filesystem(&ramfs_fs_type); | |
302 | } | |
303 | ||
304 | module_init(init_ramfs_fs) | |
305 | module_exit(exit_ramfs_fs) | |
306 | ||
307 | int __init init_rootfs(void) | |
308 | { | |
e0bf68dd PZ |
309 | int err; |
310 | ||
311 | err = bdi_init(&ramfs_backing_dev_info); | |
312 | if (err) | |
313 | return err; | |
314 | ||
315 | err = register_filesystem(&rootfs_fs_type); | |
316 | if (err) | |
317 | bdi_destroy(&ramfs_backing_dev_info); | |
318 | ||
319 | return err; | |
1da177e4 LT |
320 | } |
321 | ||
322 | MODULE_LICENSE("GPL"); |