This source file includes following definitions.
- ramfs_get_inode
- ramfs_mknod
- ramfs_mkdir
- ramfs_create
- ramfs_symlink
- ramfs_show_options
- ramfs_parse_param
- ramfs_fill_super
- ramfs_get_tree
- ramfs_free_fc
- ramfs_init_fs_context
- ramfs_kill_sb
- init_ramfs_fs
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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
43 struct ramfs_mount_opts {
44 umode_t mode;
45 };
46
47 struct ramfs_fs_info {
48 struct ramfs_mount_opts mount_opts;
49 };
50
51 #define RAMFS_DEFAULT_MODE 0755
52
53 static const struct super_operations ramfs_ops;
54 static const struct inode_operations ramfs_dir_inode_operations;
55
56 static 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
63 struct 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
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
101
102
103 static int
104 ramfs_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);
112 error = 0;
113 dir->i_mtime = dir->i_ctime = current_time(dir);
114 }
115 return error;
116 }
117
118 static 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
126 static 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
131 static 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
150 static 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
164
165 static 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
174 static const struct super_operations ramfs_ops = {
175 .statfs = simple_statfs,
176 .drop_inode = generic_delete_inode,
177 .show_options = ramfs_show_options,
178 };
179
180 enum ramfs_param {
181 Opt_mode,
182 };
183
184 static const struct fs_parameter_spec ramfs_param_specs[] = {
185 fsparam_u32oct("mode", Opt_mode),
186 {}
187 };
188
189 const struct fs_parameter_description ramfs_fs_parameters = {
190 .name = "ramfs",
191 .specs = ramfs_param_specs,
192 };
193
194 static int ramfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
195 {
196 struct fs_parse_result result;
197 struct ramfs_fs_info *fsi = fc->s_fs_info;
198 int opt;
199
200 opt = fs_parse(fc, &ramfs_fs_parameters, param, &result);
201 if (opt < 0) {
202
203
204
205
206
207
208 if (opt == -ENOPARAM)
209 opt = 0;
210 return opt;
211 }
212
213 switch (opt) {
214 case Opt_mode:
215 fsi->mount_opts.mode = result.uint_32 & S_IALLUGO;
216 break;
217 }
218
219 return 0;
220 }
221
222 static int ramfs_fill_super(struct super_block *sb, struct fs_context *fc)
223 {
224 struct ramfs_fs_info *fsi = sb->s_fs_info;
225 struct inode *inode;
226
227 sb->s_maxbytes = MAX_LFS_FILESIZE;
228 sb->s_blocksize = PAGE_SIZE;
229 sb->s_blocksize_bits = PAGE_SHIFT;
230 sb->s_magic = RAMFS_MAGIC;
231 sb->s_op = &ramfs_ops;
232 sb->s_time_gran = 1;
233
234 inode = ramfs_get_inode(sb, NULL, S_IFDIR | fsi->mount_opts.mode, 0);
235 sb->s_root = d_make_root(inode);
236 if (!sb->s_root)
237 return -ENOMEM;
238
239 return 0;
240 }
241
242 static int ramfs_get_tree(struct fs_context *fc)
243 {
244 return get_tree_nodev(fc, ramfs_fill_super);
245 }
246
247 static void ramfs_free_fc(struct fs_context *fc)
248 {
249 kfree(fc->s_fs_info);
250 }
251
252 static const struct fs_context_operations ramfs_context_ops = {
253 .free = ramfs_free_fc,
254 .parse_param = ramfs_parse_param,
255 .get_tree = ramfs_get_tree,
256 };
257
258 int ramfs_init_fs_context(struct fs_context *fc)
259 {
260 struct ramfs_fs_info *fsi;
261
262 fsi = kzalloc(sizeof(*fsi), GFP_KERNEL);
263 if (!fsi)
264 return -ENOMEM;
265
266 fsi->mount_opts.mode = RAMFS_DEFAULT_MODE;
267 fc->s_fs_info = fsi;
268 fc->ops = &ramfs_context_ops;
269 return 0;
270 }
271
272 static void ramfs_kill_sb(struct super_block *sb)
273 {
274 kfree(sb->s_fs_info);
275 kill_litter_super(sb);
276 }
277
278 static struct file_system_type ramfs_fs_type = {
279 .name = "ramfs",
280 .init_fs_context = ramfs_init_fs_context,
281 .parameters = &ramfs_fs_parameters,
282 .kill_sb = ramfs_kill_sb,
283 .fs_flags = FS_USERNS_MOUNT,
284 };
285
286 static int __init init_ramfs_fs(void)
287 {
288 return register_filesystem(&ramfs_fs_type);
289 }
290 fs_initcall(init_ramfs_fs);