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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Andrew Morton8dde0502006-02-24 13:04:23 -080030#include <linux/time.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <linux/init.h>
32#include <linux/string.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070033#include <linux/backing-dev.h>
34#include <linux/ramfs.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040035#include <linux/sched.h>
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -070036#include <linux/parser.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070037#include <asm/uaccess.h>
David Howells642fb4d2006-01-06 00:11:41 -080038#include "internal.h"
Linus Torvalds1da177e2005-04-16 15:20:36 -070039
40/* some random number */
41#define RAMFS_MAGIC 0x858458f6
42
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -070043#define RAMFS_DEFAULT_MODE 0755
44
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -080045static const struct super_operations ramfs_ops;
Arjan van de Venc5ef1c42007-02-12 00:55:40 -080046static const struct inode_operations ramfs_dir_inode_operations;
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
48static struct backing_dev_info ramfs_backing_dev_info = {
49 .ra_pages = 0, /* No readahead */
Miklos Szeredie4ad08f2008-04-30 00:54:37 -070050 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK |
Linus Torvalds1da177e2005-04-16 15:20:36 -070051 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, int mode, dev_t dev)
56{
57 struct inode * inode = new_inode(sb);
58
59 if (inode) {
60 inode->i_mode = mode;
David Howells0785f4d2008-11-14 10:39:00 +110061 inode->i_uid = current_fsuid();
62 inode->i_gid = current_fsgid();
Linus Torvalds1da177e2005-04-16 15:20:36 -070063 inode->i_mapping->a_ops = &ramfs_aops;
64 inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
Mel Gorman769848c2007-07-17 04:03:05 -070065 mapping_set_gfp_mask(inode->i_mapping, GFP_HIGHUSER);
Lee Schermerhornba9ddf42008-10-18 20:26:42 -070066 mapping_set_unevictable(inode->i_mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -070067 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) */
Dave Hansend8c76e62006-09-30 23:29:04 -070081 inc_nlink(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -070082 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, mode, dev);
99 int error = -ENOSPC;
100
101 if (inode) {
102 if (dir->i_mode & S_ISGID) {
103 inode->i_gid = dir->i_gid;
104 if (S_ISDIR(mode))
105 inode->i_mode |= S_ISGID;
106 }
107 d_instantiate(dentry, inode);
108 dget(dentry); /* Extra count - pin the dentry in core */
109 error = 0;
Andrew Morton8dde0502006-02-24 13:04:23 -0800110 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111 }
112 return error;
113}
114
115static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
116{
117 int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);
118 if (!retval)
Dave Hansend8c76e62006-09-30 23:29:04 -0700119 inc_nlink(dir);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 return retval;
121}
122
123static int ramfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
124{
125 return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);
126}
127
128static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
129{
130 struct inode *inode;
131 int error = -ENOSPC;
132
133 inode = ramfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
134 if (inode) {
135 int l = strlen(symname)+1;
136 error = page_symlink(inode, symname, l);
137 if (!error) {
138 if (dir->i_mode & S_ISGID)
139 inode->i_gid = dir->i_gid;
140 d_instantiate(dentry, inode);
141 dget(dentry);
Peter Staubachecbd3a62006-03-06 15:42:56 -0800142 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143 } else
144 iput(inode);
145 }
146 return error;
147}
148
Arjan van de Venc5ef1c42007-02-12 00:55:40 -0800149static const struct inode_operations ramfs_dir_inode_operations = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 .create = ramfs_create,
151 .lookup = simple_lookup,
152 .link = simple_link,
153 .unlink = simple_unlink,
154 .symlink = ramfs_symlink,
155 .mkdir = ramfs_mkdir,
156 .rmdir = simple_rmdir,
157 .mknod = ramfs_mknod,
158 .rename = simple_rename,
159};
160
Josef 'Jeff' Sipekee9b6d62007-02-12 00:55:41 -0800161static const struct super_operations ramfs_ops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162 .statfs = simple_statfs,
163 .drop_inode = generic_delete_inode,
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700164 .show_options = generic_show_options,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165};
166
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700167struct ramfs_mount_opts {
168 umode_t mode;
169};
170
171enum {
172 Opt_mode,
173 Opt_err
174};
175
176static const match_table_t tokens = {
177 {Opt_mode, "mode=%o"},
178 {Opt_err, NULL}
179};
180
181struct ramfs_fs_info {
182 struct ramfs_mount_opts mount_opts;
183};
184
185static int ramfs_parse_options(char *data, struct ramfs_mount_opts *opts)
186{
187 substring_t args[MAX_OPT_ARGS];
188 int option;
189 int token;
190 char *p;
191
192 opts->mode = RAMFS_DEFAULT_MODE;
193
194 while ((p = strsep(&data, ",")) != NULL) {
195 if (!*p)
196 continue;
197
198 token = match_token(p, tokens, args);
199 switch (token) {
200 case Opt_mode:
201 if (match_octal(&args[0], &option))
202 return -EINVAL;
203 opts->mode = option & S_IALLUGO;
204 break;
205 default:
206 printk(KERN_ERR "ramfs: bad mount option: %s\n", p);
207 return -EINVAL;
208 }
209 }
210
211 return 0;
212}
213
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214static int ramfs_fill_super(struct super_block * sb, void * data, int silent)
215{
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700216 struct ramfs_fs_info *fsi;
217 struct inode *inode = NULL;
218 struct dentry *root;
219 int err;
220
221 save_mount_options(sb, data);
222
223 fsi = kzalloc(sizeof(struct ramfs_fs_info), GFP_KERNEL);
Ingo Molnarf8201ab2009-04-07 14:16:50 +0800224 sb->s_fs_info = fsi;
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700225 if (!fsi) {
226 err = -ENOMEM;
227 goto fail;
228 }
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700229
230 err = ramfs_parse_options(data, &fsi->mount_opts);
231 if (err)
232 goto fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233
Ingo Molnarf8201ab2009-04-07 14:16:50 +0800234 sb->s_maxbytes = MAX_LFS_FILESIZE;
235 sb->s_blocksize = PAGE_CACHE_SIZE;
236 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
237 sb->s_magic = RAMFS_MAGIC;
238 sb->s_op = &ramfs_ops;
239 sb->s_time_gran = 1;
240
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700241 inode = ramfs_get_inode(sb, S_IFDIR | fsi->mount_opts.mode, 0);
242 if (!inode) {
243 err = -ENOMEM;
244 goto fail;
245 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246
247 root = d_alloc_root(inode);
Ingo Molnarf8201ab2009-04-07 14:16:50 +0800248 sb->s_root = root;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 if (!root) {
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700250 err = -ENOMEM;
251 goto fail;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700252 }
Ingo Molnarf8201ab2009-04-07 14:16:50 +0800253
Linus Torvalds1da177e2005-04-16 15:20:36 -0700254 return 0;
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700255fail:
256 kfree(fsi);
Ingo Molnarf8201ab2009-04-07 14:16:50 +0800257 sb->s_fs_info = NULL;
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700258 iput(inode);
259 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260}
261
David Howells454e2392006-06-23 02:02:57 -0700262int ramfs_get_sb(struct file_system_type *fs_type,
263 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264{
David Howells454e2392006-06-23 02:02:57 -0700265 return get_sb_nodev(fs_type, flags, data, ramfs_fill_super, mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266}
267
David Howells454e2392006-06-23 02:02:57 -0700268static int rootfs_get_sb(struct file_system_type *fs_type,
269 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270{
David Howells454e2392006-06-23 02:02:57 -0700271 return get_sb_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super,
272 mnt);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273}
274
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700275static void ramfs_kill_sb(struct super_block *sb)
276{
277 kfree(sb->s_fs_info);
278 kill_litter_super(sb);
279}
280
Linus Torvalds1da177e2005-04-16 15:20:36 -0700281static struct file_system_type ramfs_fs_type = {
282 .name = "ramfs",
283 .get_sb = ramfs_get_sb,
Wu Fengguangc3b1b1c2009-03-31 15:24:34 -0700284 .kill_sb = ramfs_kill_sb,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285};
286static struct file_system_type rootfs_fs_type = {
287 .name = "rootfs",
288 .get_sb = rootfs_get_sb,
289 .kill_sb = kill_litter_super,
290};
291
292static int __init init_ramfs_fs(void)
293{
294 return register_filesystem(&ramfs_fs_type);
295}
296
297static void __exit exit_ramfs_fs(void)
298{
299 unregister_filesystem(&ramfs_fs_type);
300}
301
302module_init(init_ramfs_fs)
303module_exit(exit_ramfs_fs)
304
305int __init init_rootfs(void)
306{
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700307 int err;
308
309 err = bdi_init(&ramfs_backing_dev_info);
310 if (err)
311 return err;
312
313 err = register_filesystem(&rootfs_fs_type);
314 if (err)
315 bdi_destroy(&ramfs_backing_dev_info);
316
317 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318}
319
320MODULE_LICENSE("GPL");