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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 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
53static struct backing_dev_info ramfs_backing_dev_info = {
54 .name = "ramfs",
55 .ra_pages = 0, /* No readahead */
56 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK |
57 BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
58 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,
59};
60
61struct inode *ramfs_get_inode(struct super_block *sb,
62 const struct inode *dir, umode_t mode, dev_t dev)
63{
64 struct inode * inode = new_inode(sb);
65
66 if (inode) {
67 inode->i_ino = get_next_ino();
68 inode_init_owner(inode, dir, mode);
69 inode->i_mapping->a_ops = &ramfs_aops;
70 inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
71 mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
72 mapping_set_unevictable(inode->i_mapping);
73 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
74 switch (mode & S_IFMT) {
75 default:
76 init_special_inode(inode, mode, dev);
77 break;
78 case S_IFREG:
79 inode->i_op = &ramfs_file_inode_operations;
80 inode->i_fop = &ramfs_file_operations;
81 break;
82 case S_IFDIR:
83 inode->i_op = &ramfs_dir_inode_operations;
84 inode->i_fop = &simple_dir_operations;
85
86 /* directory inodes start off with i_nlink == 2 (for "." entry) */
87 inc_nlink(inode);
88 break;
89 case S_IFLNK:
90 inode->i_op = &page_symlink_inode_operations;
91 break;
92 }
93 }
94 return inode;
95}
96
97/*
98 * File creation. Allocate an inode, and we're done..
99 */
100/* SMP-safe */
101static int
102ramfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
103{
104 struct inode * inode = ramfs_get_inode(dir->i_sb, dir, mode, dev);
105 int error = -ENOSPC;
106
107 if (inode) {
108 d_instantiate(dentry, inode);
109 dget(dentry); /* Extra count - pin the dentry in core */
110 error = 0;
111 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
112 }
113 return error;
114}
115
116static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, umode_t mode)
117{
118 int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);
119 if (!retval)
120 inc_nlink(dir);
121 return retval;
122}
123
124static int ramfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
125{
126 return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);
127}
128
129static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
130{
131 struct inode *inode;
132 int error = -ENOSPC;
133
134 inode = ramfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
135 if (inode) {
136 int l = strlen(symname)+1;
137 error = page_symlink(inode, symname, l);
138 if (!error) {
139 d_instantiate(dentry, inode);
140 dget(dentry);
141 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
142 } else
143 iput(inode);
144 }
145 return error;
146}
147
148static const struct inode_operations ramfs_dir_inode_operations = {
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
160static const struct super_operations ramfs_ops = {
161 .statfs = simple_statfs,
162 .drop_inode = generic_delete_inode,
163 .show_options = generic_show_options,
164};
165
166struct ramfs_mount_opts {
167 umode_t mode;
168};
169
170enum {
171 Opt_mode,
172 Opt_err
173};
174
175static const match_table_t tokens = {
176 {Opt_mode, "mode=%o"},
177 {Opt_err, NULL}
178};
179
180struct ramfs_fs_info {
181 struct ramfs_mount_opts mount_opts;
182};
183
184static 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;
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 */
210 }
211 }
212
213 return 0;
214}
215
216int ramfs_fill_super(struct super_block *sb, void *data, int silent)
217{
218 struct ramfs_fs_info *fsi;
219 struct inode *inode;
220 int err;
221
222 save_mount_options(sb, data);
223
224 fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
225 sb->s_fs_info = fsi;
226 if (!fsi)
227 return -ENOMEM;
228
229 err = ramfs_parse_options(data, &fsi->mount_opts);
230 if (err)
231 return err;
232
233 sb->s_maxbytes = MAX_LFS_FILESIZE;
234 sb->s_blocksize = PAGE_CACHE_SIZE;
235 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
236 sb->s_magic = RAMFS_MAGIC;
237 sb->s_op = &ramfs_ops;
238 sb->s_time_gran = 1;
239
240 inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
241 sb->s_root = d_make_root(inode);
242 if (!sb->s_root)
243 return -ENOMEM;
244
245 return 0;
246}
247
248struct dentry *ramfs_mount(struct file_system_type *fs_type,
249 int flags, const char *dev_name, void *data)
250{
251 return mount_nodev(fs_type, flags, data, ramfs_fill_super);
252}
253
254static void ramfs_kill_sb(struct super_block *sb)
255{
256 kfree(sb->s_fs_info);
257 kill_litter_super(sb);
258}
259
260static struct file_system_type ramfs_fs_type = {
261 .name = "ramfs",
262 .mount = ramfs_mount,
263 .kill_sb = ramfs_kill_sb,
264 .fs_flags = FS_USERNS_MOUNT,
265};
266
267int __init init_ramfs_fs(void)
268{
269 static unsigned long once;
270 int err;
271
272 if (test_and_set_bit(0, &once))
273 return 0;
274
275 err = bdi_init(&ramfs_backing_dev_info);
276 if (err)
277 return err;
278
279 err = register_filesystem(&ramfs_fs_type);
280 if (err)
281 bdi_destroy(&ramfs_backing_dev_info);
282
283 return err;
284}
285fs_initcall(init_ramfs_fs);
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}