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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/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 <asm/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 struct backing_dev_info ramfs_backing_dev_info = {
47 .name = "ramfs",
48 .ra_pages = 0, /* No readahead */
49 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK |
50 BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
51 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,
52};
53
54struct inode *ramfs_get_inode(struct super_block *sb,
55 const struct inode *dir, umode_t mode, dev_t dev)
56{
57 struct inode * inode = new_inode(sb);
58
59 if (inode) {
60 inode->i_ino = get_next_ino();
61 inode_init_owner(inode, dir, mode);
62 inode->i_mapping->a_ops = &ramfs_aops;
63 inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
64 mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
65 mapping_set_unevictable(inode->i_mapping);
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) */
80 inc_nlink(inode);
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 */
94static int
95ramfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
96{
97 struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev);
98 int error = -ENOSPC;
99
100 if (inode) {
101 d_instantiate(dentry, inode);
102 dget(dentry); /* Extra count - pin the dentry in core */
103 error = 0;
104 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
105 }
106 return error;
107}
108
109static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
110{
111 int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);
112 if (!retval)
113 inc_nlink(dir);
114 return retval;
115}
116
117static int ramfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, struct nameidata *nd)
118{
119 return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);
120}
121
122static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
123{
124 struct inode *inode;
125 int error = -ENOSPC;
126
127 inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
128 if (inode) {
129 int l = strlen(symname)+1;
130 error = page_symlink(inode, symname, l);
131 if (!error) {
132 d_instantiate(dentry, inode);
133 dget(dentry);
134 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
135 } else
136 iput(inode);
137 }
138 return error;
139}
140
141static const struct inode_operations ramfs_dir_inode_operations = {
142 .create = ramfs_create,
143 .lookup = simple_lookup,
144 .link = simple_link,
145 .unlink = simple_unlink,
146 .symlink = ramfs_symlink,
147 .mkdir = ramfs_mkdir,
148 .rmdir = simple_rmdir,
149 .mknod = ramfs_mknod,
150 .rename = simple_rename,
151};
152
153static const struct super_operations ramfs_ops = {
154 .statfs = simple_statfs,
155 .drop_inode = generic_delete_inode,
156 .show_options = generic_show_options,
157};
158
159struct ramfs_mount_opts {
160 umode_t mode;
161};
162
163enum {
164 Opt_mode,
165 Opt_err
166};
167
168static const match_table_t tokens = {
169 {Opt_mode, "mode=%o"},
170 {Opt_err, NULL}
171};
172
173struct ramfs_fs_info {
174 struct ramfs_mount_opts mount_opts;
175};
176
177static int ramfs_parse_options(char *data, struct ramfs_mount_opts *opts)
178{
179 substring_t args[MAX_OPT_ARGS];
180 int option;
181 int token;
182 char *p;
183
184 opts->mode = RAMFS_DEFAULT_MODE;
185
186 while ((p = strsep(&data, ",")) != NULL) {
187 if (!*p)
188 continue;
189
190 token = match_token(p, tokens, args);
191 switch (token) {
192 case Opt_mode:
193 if (match_octal(&args[0], &option))
194 return -EINVAL;
195 opts->mode = option & S_IALLUGO;
196 break;
197 /*
198 * We might like to report bad mount options here;
199 * but traditionally ramfs has ignored all mount options,
200 * and as it is used as a !CONFIG_SHMEM simple substitute
201 * for tmpfs, better continue to ignore other mount options.
202 */
203 }
204 }
205
206 return 0;
207}
208
209int ramfs_fill_super(struct super_block *sb, void *data, int silent)
210{
211 struct ramfs_fs_info *fsi;
212 struct inode *inode;
213 int err;
214
215 save_mount_options(sb, data);
216
217 fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
218 sb->s_fs_info = fsi;
219 if (!fsi)
220 return -ENOMEM;
221
222 err = ramfs_parse_options(data, &fsi->mount_opts);
223 if (err)
224 return err;
225
226 sb->s_maxbytes = MAX_LFS_FILESIZE;
227 sb->s_blocksize = PAGE_CACHE_SIZE;
228 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
229 sb->s_magic = RAMFS_MAGIC;
230 sb->s_op = &ramfs_ops;
231 sb->s_time_gran = 1;
232
233 inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
234 sb->s_root = d_make_root(inode);
235 if (!sb->s_root)
236 return -ENOMEM;
237
238 return 0;
239}
240
241struct dentry *ramfs_mount(struct file_system_type *fs_type,
242 int flags, const char *dev_name, void *data)
243{
244 return mount_nodev(fs_type, flags, data, ramfs_fill_super);
245}
246
247static struct dentry *rootfs_mount(struct file_system_type *fs_type,
248 int flags, const char *dev_name, void *data)
249{
250 return mount_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super);
251}
252
253static void ramfs_kill_sb(struct super_block *sb)
254{
255 kfree(sb->s_fs_info);
256 kill_litter_super(sb);
257}
258
259static struct file_system_type ramfs_fs_type = {
260 .name = "ramfs",
261 .mount = ramfs_mount,
262 .kill_sb = ramfs_kill_sb,
263};
264static struct file_system_type rootfs_fs_type = {
265 .name = "rootfs",
266 .mount = rootfs_mount,
267 .kill_sb = kill_litter_super,
268};
269
270static int __init init_ramfs_fs(void)
271{
272 return register_filesystem(&ramfs_fs_type);
273}
274module_init(init_ramfs_fs)
275
276int __init init_rootfs(void)
277{
278 int err;
279
280 err = bdi_init(&ramfs_backing_dev_info);
281 if (err)
282 return err;
283
284 err = register_filesystem(&rootfs_fs_type);
285 if (err)
286 bdi_destroy(&ramfs_backing_dev_info);
287
288 return err;
289}
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 <linux/fs_context.h>
40#include <linux/fs_parser.h>
41#include "internal.h"
42
43struct ramfs_mount_opts {
44 umode_t mode;
45};
46
47struct ramfs_fs_info {
48 struct ramfs_mount_opts mount_opts;
49};
50
51#define RAMFS_DEFAULT_MODE 0755
52
53static const struct super_operations ramfs_ops;
54static const struct inode_operations ramfs_dir_inode_operations;
55
56static const struct address_space_operations ramfs_aops = {
57 .readpage = simple_readpage,
58 .write_begin = simple_write_begin,
59 .write_end = simple_write_end,
60 .set_page_dirty = __set_page_dirty_no_writeback,
61};
62
63struct inode *ramfs_get_inode(struct super_block *sb,
64 const struct inode *dir, umode_t mode, dev_t dev)
65{
66 struct inode * inode = new_inode(sb);
67
68 if (inode) {
69 inode->i_ino = get_next_ino();
70 inode_init_owner(inode, dir, mode);
71 inode->i_mapping->a_ops = &ramfs_aops;
72 mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
73 mapping_set_unevictable(inode->i_mapping);
74 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
75 switch (mode & S_IFMT) {
76 default:
77 init_special_inode(inode, mode, dev);
78 break;
79 case S_IFREG:
80 inode->i_op = &ramfs_file_inode_operations;
81 inode->i_fop = &ramfs_file_operations;
82 break;
83 case S_IFDIR:
84 inode->i_op = &ramfs_dir_inode_operations;
85 inode->i_fop = &simple_dir_operations;
86
87 /* directory inodes start off with i_nlink == 2 (for "." entry) */
88 inc_nlink(inode);
89 break;
90 case S_IFLNK:
91 inode->i_op = &page_symlink_inode_operations;
92 inode_nohighmem(inode);
93 break;
94 }
95 }
96 return inode;
97}
98
99/*
100 * File creation. Allocate an inode, and we're done..
101 */
102/* SMP-safe */
103static int
104ramfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
105{
106 struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev);
107 int error = -ENOSPC;
108
109 if (inode) {
110 d_instantiate(dentry, inode);
111 dget(dentry); /* Extra count - pin the dentry in core */
112 error = 0;
113 dir->i_mtime = dir->i_ctime = current_time(dir);
114 }
115 return error;
116}
117
118static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
119{
120 int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);
121 if (!retval)
122 inc_nlink(dir);
123 return retval;
124}
125
126static int ramfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
127{
128 return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);
129}
130
131static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
132{
133 struct inode *inode;
134 int error = -ENOSPC;
135
136 inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
137 if (inode) {
138 int l = strlen(symname)+1;
139 error = page_symlink(inode, symname, l);
140 if (!error) {
141 d_instantiate(dentry, inode);
142 dget(dentry);
143 dir->i_mtime = dir->i_ctime = current_time(dir);
144 } else
145 iput(inode);
146 }
147 return error;
148}
149
150static const struct inode_operations ramfs_dir_inode_operations = {
151 .create = ramfs_create,
152 .lookup = simple_lookup,
153 .link = simple_link,
154 .unlink = simple_unlink,
155 .symlink = ramfs_symlink,
156 .mkdir = ramfs_mkdir,
157 .rmdir = simple_rmdir,
158 .mknod = ramfs_mknod,
159 .rename = simple_rename,
160};
161
162/*
163 * Display the mount options in /proc/mounts.
164 */
165static int ramfs_show_options(struct seq_file *m, struct dentry *root)
166{
167 struct ramfs_fs_info *fsi = root->d_sb->s_fs_info;
168
169 if (fsi->mount_opts.mode != RAMFS_DEFAULT_MODE)
170 seq_printf(m, ",mode=%o", fsi->mount_opts.mode);
171 return 0;
172}
173
174static const struct super_operations ramfs_ops = {
175 .statfs = simple_statfs,
176 .drop_inode = generic_delete_inode,
177 .show_options = ramfs_show_options,
178};
179
180enum ramfs_param {
181 Opt_mode,
182};
183
184const struct fs_parameter_spec ramfs_fs_parameters[] = {
185 fsparam_u32oct("mode", Opt_mode),
186 {}
187};
188
189static int ramfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
190{
191 struct fs_parse_result result;
192 struct ramfs_fs_info *fsi = fc->s_fs_info;
193 int opt;
194
195 opt = fs_parse(fc, ramfs_fs_parameters, param, &result);
196 if (opt < 0) {
197 /*
198 * We might like to report bad mount options here;
199 * but traditionally ramfs has ignored all mount options,
200 * and as it is used as a !CONFIG_SHMEM simple substitute
201 * for tmpfs, better continue to ignore other mount options.
202 */
203 if (opt == -ENOPARAM)
204 opt = 0;
205 return opt;
206 }
207
208 switch (opt) {
209 case Opt_mode:
210 fsi->mount_opts.mode = result.uint_32 & S_IALLUGO;
211 break;
212 }
213
214 return 0;
215}
216
217static int ramfs_fill_super(struct super_block *sb, struct fs_context *fc)
218{
219 struct ramfs_fs_info *fsi = sb->s_fs_info;
220 struct inode *inode;
221
222 sb->s_maxbytes = MAX_LFS_FILESIZE;
223 sb->s_blocksize = PAGE_SIZE;
224 sb->s_blocksize_bits = PAGE_SHIFT;
225 sb->s_magic = RAMFS_MAGIC;
226 sb->s_op = &ramfs_ops;
227 sb->s_time_gran = 1;
228
229 inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
230 sb->s_root = d_make_root(inode);
231 if (!sb->s_root)
232 return -ENOMEM;
233
234 return 0;
235}
236
237static int ramfs_get_tree(struct fs_context *fc)
238{
239 return get_tree_nodev(fc, ramfs_fill_super);
240}
241
242static void ramfs_free_fc(struct fs_context *fc)
243{
244 kfree(fc->s_fs_info);
245}
246
247static const struct fs_context_operations ramfs_context_ops = {
248 .free = ramfs_free_fc,
249 .parse_param = ramfs_parse_param,
250 .get_tree = ramfs_get_tree,
251};
252
253int ramfs_init_fs_context(struct fs_context *fc)
254{
255 struct ramfs_fs_info *fsi;
256
257 fsi = kzalloc(sizeof(*fsi), GFP_KERNEL);
258 if (!fsi)
259 return -ENOMEM;
260
261 fsi->mount_opts.mode = RAMFS_DEFAULT_MODE;
262 fc->s_fs_info = fsi;
263 fc->ops = &ramfs_context_ops;
264 return 0;
265}
266
267static void ramfs_kill_sb(struct super_block *sb)
268{
269 kfree(sb->s_fs_info);
270 kill_litter_super(sb);
271}
272
273static struct file_system_type ramfs_fs_type = {
274 .name = "ramfs",
275 .init_fs_context = ramfs_init_fs_context,
276 .parameters = ramfs_fs_parameters,
277 .kill_sb = ramfs_kill_sb,
278 .fs_flags = FS_USERNS_MOUNT,
279};
280
281static int __init init_ramfs_fs(void)
282{
283 return register_filesystem(&ramfs_fs_type);
284}
285fs_initcall(init_ramfs_fs);