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Commit | Line | Data |
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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> |
5a0e3ad6 | 38 | #include <linux/slab.h> |
1da177e4 | 39 | #include <asm/uaccess.h> |
642fb4d1 | 40 | #include "internal.h" |
1da177e4 | 41 | |
c3b1b1cb WF |
42 | #define RAMFS_DEFAULT_MODE 0755 |
43 | ||
ee9b6d61 | 44 | static const struct super_operations ramfs_ops; |
c5ef1c42 | 45 | static const struct inode_operations ramfs_dir_inode_operations; |
1da177e4 LT |
46 | |
47 | static struct backing_dev_info ramfs_backing_dev_info = { | |
d993831f | 48 | .name = "ramfs", |
1da177e4 | 49 | .ra_pages = 0, /* No readahead */ |
e4ad08fe | 50 | .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | |
1da177e4 LT |
51 | BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY | |
52 | BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP, | |
53 | }; | |
54 | ||
454abafe DM |
55 | struct inode *ramfs_get_inode(struct super_block *sb, |
56 | const struct inode *dir, int mode, dev_t dev) | |
1da177e4 LT |
57 | { |
58 | struct inode * inode = new_inode(sb); | |
59 | ||
60 | if (inode) { | |
85fe4025 | 61 | inode->i_ino = get_next_ino(); |
454abafe | 62 | inode_init_owner(inode, dir, mode); |
1da177e4 LT |
63 | inode->i_mapping->a_ops = &ramfs_aops; |
64 | inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info; | |
769848c0 | 65 | mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER); |
ba9ddf49 | 66 | mapping_set_unevictable(inode->i_mapping); |
1da177e4 LT |
67 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
68 | switch (mode & S_IFMT) { | |
69 | default: | |
70 | init_special_inode(inode, mode, dev); | |
71 | break; | |
72 | case S_IFREG: | |
73 | inode->i_op = &ramfs_file_inode_operations; | |
74 | inode->i_fop = &ramfs_file_operations; | |
75 | break; | |
76 | case S_IFDIR: | |
77 | inode->i_op = &ramfs_dir_inode_operations; | |
78 | inode->i_fop = &simple_dir_operations; | |
79 | ||
80 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
d8c76e6f | 81 | inc_nlink(inode); |
1da177e4 LT |
82 | break; |
83 | case S_IFLNK: | |
84 | inode->i_op = &page_symlink_inode_operations; | |
85 | break; | |
86 | } | |
87 | } | |
88 | return inode; | |
89 | } | |
90 | ||
91 | /* | |
92 | * File creation. Allocate an inode, and we're done.. | |
93 | */ | |
94 | /* SMP-safe */ | |
95 | static int | |
96 | ramfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) | |
97 | { | |
454abafe | 98 | struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev); |
1da177e4 LT |
99 | int error = -ENOSPC; |
100 | ||
101 | if (inode) { | |
1da177e4 LT |
102 | d_instantiate(dentry, inode); |
103 | dget(dentry); /* Extra count - pin the dentry in core */ | |
104 | error = 0; | |
8dde0509 | 105 | dir->i_mtime = dir->i_ctime = CURRENT_TIME; |
1da177e4 LT |
106 | } |
107 | return error; | |
108 | } | |
109 | ||
110 | static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode) | |
111 | { | |
112 | int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0); | |
113 | if (!retval) | |
d8c76e6f | 114 | inc_nlink(dir); |
1da177e4 LT |
115 | return retval; |
116 | } | |
117 | ||
118 | static int ramfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd) | |
119 | { | |
120 | return ramfs_mknod(dir, dentry, mode | S_IFREG, 0); | |
121 | } | |
122 | ||
123 | static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname) | |
124 | { | |
125 | struct inode *inode; | |
126 | int error = -ENOSPC; | |
127 | ||
454abafe | 128 | inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0); |
1da177e4 LT |
129 | if (inode) { |
130 | int l = strlen(symname)+1; | |
131 | error = page_symlink(inode, symname, l); | |
132 | if (!error) { | |
1da177e4 LT |
133 | d_instantiate(dentry, inode); |
134 | dget(dentry); | |
ecbd3a63 | 135 | dir->i_mtime = dir->i_ctime = CURRENT_TIME; |
1da177e4 LT |
136 | } else |
137 | iput(inode); | |
138 | } | |
139 | return error; | |
140 | } | |
141 | ||
c5ef1c42 | 142 | static const struct inode_operations ramfs_dir_inode_operations = { |
1da177e4 LT |
143 | .create = ramfs_create, |
144 | .lookup = simple_lookup, | |
145 | .link = simple_link, | |
146 | .unlink = simple_unlink, | |
147 | .symlink = ramfs_symlink, | |
148 | .mkdir = ramfs_mkdir, | |
149 | .rmdir = simple_rmdir, | |
150 | .mknod = ramfs_mknod, | |
151 | .rename = simple_rename, | |
152 | }; | |
153 | ||
ee9b6d61 | 154 | static const struct super_operations ramfs_ops = { |
1da177e4 LT |
155 | .statfs = simple_statfs, |
156 | .drop_inode = generic_delete_inode, | |
c3b1b1cb WF |
157 | .show_options = generic_show_options, |
158 | }; | |
159 | ||
160 | struct ramfs_mount_opts { | |
161 | umode_t mode; | |
162 | }; | |
163 | ||
164 | enum { | |
165 | Opt_mode, | |
166 | Opt_err | |
167 | }; | |
168 | ||
169 | static const match_table_t tokens = { | |
170 | {Opt_mode, "mode=%o"}, | |
171 | {Opt_err, NULL} | |
172 | }; | |
173 | ||
174 | struct ramfs_fs_info { | |
175 | struct ramfs_mount_opts mount_opts; | |
1da177e4 LT |
176 | }; |
177 | ||
c3b1b1cb WF |
178 | static int ramfs_parse_options(char *data, struct ramfs_mount_opts *opts) |
179 | { | |
180 | substring_t args[MAX_OPT_ARGS]; | |
181 | int option; | |
182 | int token; | |
183 | char *p; | |
184 | ||
185 | opts->mode = RAMFS_DEFAULT_MODE; | |
186 | ||
187 | while ((p = strsep(&data, ",")) != NULL) { | |
188 | if (!*p) | |
189 | continue; | |
190 | ||
191 | token = match_token(p, tokens, args); | |
192 | switch (token) { | |
193 | case Opt_mode: | |
194 | if (match_octal(&args[0], &option)) | |
195 | return -EINVAL; | |
196 | opts->mode = option & S_IALLUGO; | |
197 | break; | |
0a8eba9b MF |
198 | /* |
199 | * We might like to report bad mount options here; | |
200 | * but traditionally ramfs has ignored all mount options, | |
201 | * and as it is used as a !CONFIG_SHMEM simple substitute | |
202 | * for tmpfs, better continue to ignore other mount options. | |
203 | */ | |
c3b1b1cb WF |
204 | } |
205 | } | |
206 | ||
207 | return 0; | |
208 | } | |
209 | ||
da5e4ef7 | 210 | int ramfs_fill_super(struct super_block *sb, void *data, int silent) |
1da177e4 | 211 | { |
c3b1b1cb WF |
212 | struct ramfs_fs_info *fsi; |
213 | struct inode *inode = NULL; | |
214 | struct dentry *root; | |
215 | int err; | |
216 | ||
217 | save_mount_options(sb, data); | |
218 | ||
219 | fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL); | |
f8201abc | 220 | sb->s_fs_info = fsi; |
c3b1b1cb WF |
221 | if (!fsi) { |
222 | err = -ENOMEM; | |
223 | goto fail; | |
224 | } | |
c3b1b1cb WF |
225 | |
226 | err = ramfs_parse_options(data, &fsi->mount_opts); | |
227 | if (err) | |
228 | goto fail; | |
1da177e4 | 229 | |
f8201abc IM |
230 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
231 | sb->s_blocksize = PAGE_CACHE_SIZE; | |
232 | sb->s_blocksize_bits = PAGE_CACHE_SHIFT; | |
233 | sb->s_magic = RAMFS_MAGIC; | |
234 | sb->s_op = &ramfs_ops; | |
235 | sb->s_time_gran = 1; | |
236 | ||
454abafe | 237 | inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0); |
c3b1b1cb WF |
238 | if (!inode) { |
239 | err = -ENOMEM; | |
240 | goto fail; | |
241 | } | |
1da177e4 LT |
242 | |
243 | root = d_alloc_root(inode); | |
f8201abc | 244 | sb->s_root = root; |
1da177e4 | 245 | if (!root) { |
c3b1b1cb WF |
246 | err = -ENOMEM; |
247 | goto fail; | |
1da177e4 | 248 | } |
f8201abc | 249 | |
1da177e4 | 250 | return 0; |
c3b1b1cb WF |
251 | fail: |
252 | kfree(fsi); | |
f8201abc | 253 | sb->s_fs_info = NULL; |
c3b1b1cb WF |
254 | iput(inode); |
255 | return err; | |
1da177e4 LT |
256 | } |
257 | ||
3c26ff6e AV |
258 | struct dentry *ramfs_mount(struct file_system_type *fs_type, |
259 | int flags, const char *dev_name, void *data) | |
1da177e4 | 260 | { |
3c26ff6e | 261 | return mount_nodev(fs_type, flags, data, ramfs_fill_super); |
1da177e4 LT |
262 | } |
263 | ||
3c26ff6e AV |
264 | static struct dentry *rootfs_mount(struct file_system_type *fs_type, |
265 | int flags, const char *dev_name, void *data) | |
1da177e4 | 266 | { |
3c26ff6e | 267 | return mount_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super); |
1da177e4 LT |
268 | } |
269 | ||
c3b1b1cb WF |
270 | static void ramfs_kill_sb(struct super_block *sb) |
271 | { | |
272 | kfree(sb->s_fs_info); | |
273 | kill_litter_super(sb); | |
274 | } | |
275 | ||
1da177e4 LT |
276 | static struct file_system_type ramfs_fs_type = { |
277 | .name = "ramfs", | |
3c26ff6e | 278 | .mount = ramfs_mount, |
c3b1b1cb | 279 | .kill_sb = ramfs_kill_sb, |
1da177e4 LT |
280 | }; |
281 | static struct file_system_type rootfs_fs_type = { | |
282 | .name = "rootfs", | |
3c26ff6e | 283 | .mount = rootfs_mount, |
1da177e4 LT |
284 | .kill_sb = kill_litter_super, |
285 | }; | |
286 | ||
287 | static int __init init_ramfs_fs(void) | |
288 | { | |
289 | return register_filesystem(&ramfs_fs_type); | |
290 | } | |
291 | ||
292 | static void __exit exit_ramfs_fs(void) | |
293 | { | |
294 | unregister_filesystem(&ramfs_fs_type); | |
295 | } | |
296 | ||
297 | module_init(init_ramfs_fs) | |
298 | module_exit(exit_ramfs_fs) | |
299 | ||
300 | int __init init_rootfs(void) | |
301 | { | |
e0bf68dd PZ |
302 | int err; |
303 | ||
304 | err = bdi_init(&ramfs_backing_dev_info); | |
305 | if (err) | |
306 | return err; | |
307 | ||
308 | err = register_filesystem(&rootfs_fs_type); | |
309 | if (err) | |
310 | bdi_destroy(&ramfs_backing_dev_info); | |
311 | ||
312 | return err; | |
1da177e4 LT |
313 | } |
314 | ||
315 | MODULE_LICENSE("GPL"); |