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