1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
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
41struct ramfs_mount_opts {
42 umode_t mode;
43};
44
45struct ramfs_fs_info {
46 struct ramfs_mount_opts mount_opts;
47};
48
49#define RAMFS_DEFAULT_MODE 0755
50
51static const struct super_operations ramfs_ops;
52static const struct inode_operations ramfs_dir_inode_operations;
53
54static const struct address_space_operations ramfs_aops = {
55 .readpage = simple_readpage,
56 .write_begin = simple_write_begin,
57 .write_end = simple_write_end,
58 .set_page_dirty = __set_page_dirty_no_writeback,
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 mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
71 mapping_set_unevictable(inode->i_mapping);
72 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
73 switch (mode & S_IFMT) {
74 default:
75 init_special_inode(inode, mode, dev);
76 break;
77 case S_IFREG:
78 inode->i_op = &ramfs_file_inode_operations;
79 inode->i_fop = &ramfs_file_operations;
80 break;
81 case S_IFDIR:
82 inode->i_op = &ramfs_dir_inode_operations;
83 inode->i_fop = &simple_dir_operations;
84
85
86 inc_nlink(inode);
87 break;
88 case S_IFLNK:
89 inode->i_op = &page_symlink_inode_operations;
90 inode_nohighmem(inode);
91 break;
92 }
93 }
94 return inode;
95}
96
97
98
99
100
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);
110 error = 0;
111 dir->i_mtime = dir->i_ctime = current_time(dir);
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(dir);
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
160
161
162
163static int ramfs_show_options(struct seq_file *m, struct dentry *root)
164{
165 struct ramfs_fs_info *fsi = root->d_sb->s_fs_info;
166
167 if (fsi->mount_opts.mode != RAMFS_DEFAULT_MODE)
168 seq_printf(m, ",mode=%o", fsi->mount_opts.mode);
169 return 0;
170}
171
172static const struct super_operations ramfs_ops = {
173 .statfs = simple_statfs,
174 .drop_inode = generic_delete_inode,
175 .show_options = ramfs_show_options,
176};
177
178enum {
179 Opt_mode,
180 Opt_err
181};
182
183static const match_table_t tokens = {
184 {Opt_mode, "mode=%o"},
185 {Opt_err, NULL}
186};
187
188static int ramfs_parse_options(char *data, struct ramfs_mount_opts *opts)
189{
190 substring_t args[MAX_OPT_ARGS];
191 int option;
192 int token;
193 char *p;
194
195 opts->mode = RAMFS_DEFAULT_MODE;
196
197 while ((p = strsep(&data, ",")) != NULL) {
198 if (!*p)
199 continue;
200
201 token = match_token(p, tokens, args);
202 switch (token) {
203 case Opt_mode:
204 if (match_octal(&args[0], &option))
205 return -EINVAL;
206 opts->mode = option & S_IALLUGO;
207 break;
208
209
210
211
212
213
214 }
215 }
216
217 return 0;
218}
219
220int ramfs_fill_super(struct super_block *sb, void *data, int silent)
221{
222 struct ramfs_fs_info *fsi;
223 struct inode *inode;
224 int err;
225
226 fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
227 sb->s_fs_info = fsi;
228 if (!fsi)
229 return -ENOMEM;
230
231 err = ramfs_parse_options(data, &fsi->mount_opts);
232 if (err)
233 return err;
234
235 sb->s_maxbytes = MAX_LFS_FILESIZE;
236 sb->s_blocksize = PAGE_SIZE;
237 sb->s_blocksize_bits = PAGE_SHIFT;
238 sb->s_magic = RAMFS_MAGIC;
239 sb->s_op = &ramfs_ops;
240 sb->s_time_gran = 1;
241
242 inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
243 sb->s_root = d_make_root(inode);
244 if (!sb->s_root)
245 return -ENOMEM;
246
247 return 0;
248}
249
250struct dentry *ramfs_mount(struct file_system_type *fs_type,
251 int flags, const char *dev_name, void *data)
252{
253 return mount_nodev(fs_type, flags, data, ramfs_fill_super);
254}
255
256static void ramfs_kill_sb(struct super_block *sb)
257{
258 kfree(sb->s_fs_info);
259 kill_litter_super(sb);
260}
261
262static struct file_system_type ramfs_fs_type = {
263 .name = "ramfs",
264 .mount = ramfs_mount,
265 .kill_sb = ramfs_kill_sb,
266 .fs_flags = FS_USERNS_MOUNT,
267};
268
269int __init init_ramfs_fs(void)
270{
271 static unsigned long once;
272
273 if (test_and_set_bit(0, &once))
274 return 0;
275 return register_filesystem(&ramfs_fs_type);
276}
277fs_initcall(init_ramfs_fs);
278
