ia64/linux-2.6.18-xen.hg

view fs/ramfs/inode.c @ 524:7f8b544237bf

netfront: Allow netfront in domain 0.

This is useful if your physical network device is in a utility domain.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Tue Apr 15 15:18:58 2008 +0100 (2008-04-15)
parents 831230e53067
children
line source
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 */
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 */
26 #include <linux/module.h>
27 #include <linux/fs.h>
28 #include <linux/pagemap.h>
29 #include <linux/highmem.h>
30 #include <linux/time.h>
31 #include <linux/init.h>
32 #include <linux/string.h>
33 #include <linux/smp_lock.h>
34 #include <linux/backing-dev.h>
35 #include <linux/ramfs.h>
37 #include <asm/uaccess.h>
38 #include "internal.h"
40 /* some random number */
41 #define RAMFS_MAGIC 0x858458f6
43 static struct super_operations ramfs_ops;
44 static struct inode_operations ramfs_dir_inode_operations;
46 static struct backing_dev_info ramfs_backing_dev_info = {
47 .ra_pages = 0, /* No readahead */
48 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK |
49 BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
50 BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP,
51 };
53 struct inode *ramfs_get_inode(struct super_block *sb, int mode, dev_t dev)
54 {
55 struct inode * inode = new_inode(sb);
57 if (inode) {
58 inode->i_mode = mode;
59 inode->i_uid = current->fsuid;
60 inode->i_gid = current->fsgid;
61 inode->i_blksize = PAGE_CACHE_SIZE;
62 inode->i_blocks = 0;
63 inode->i_mapping->a_ops = &ramfs_aops;
64 inode->i_mapping->backing_dev_info = &ramfs_backing_dev_info;
65 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
66 switch (mode & S_IFMT) {
67 default:
68 init_special_inode(inode, mode, dev);
69 break;
70 case S_IFREG:
71 inode->i_op = &ramfs_file_inode_operations;
72 inode->i_fop = &ramfs_file_operations;
73 break;
74 case S_IFDIR:
75 inode->i_op = &ramfs_dir_inode_operations;
76 inode->i_fop = &simple_dir_operations;
78 /* directory inodes start off with i_nlink == 2 (for "." entry) */
79 inode->i_nlink++;
80 break;
81 case S_IFLNK:
82 inode->i_op = &page_symlink_inode_operations;
83 break;
84 }
85 }
86 return inode;
87 }
89 /*
90 * File creation. Allocate an inode, and we're done..
91 */
92 /* SMP-safe */
93 static int
94 ramfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
95 {
96 struct inode * inode = ramfs_get_inode(dir->i_sb, mode, dev);
97 int error = -ENOSPC;
99 if (inode) {
100 if (dir->i_mode & S_ISGID) {
101 inode->i_gid = dir->i_gid;
102 if (S_ISDIR(mode))
103 inode->i_mode |= S_ISGID;
104 }
105 d_instantiate(dentry, inode);
106 dget(dentry); /* Extra count - pin the dentry in core */
107 error = 0;
108 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
109 }
110 return error;
111 }
113 static int ramfs_mkdir(struct inode * dir, struct dentry * dentry, int mode)
114 {
115 int retval = ramfs_mknod(dir, dentry, mode | S_IFDIR, 0);
116 if (!retval)
117 dir->i_nlink++;
118 return retval;
119 }
121 static int ramfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
122 {
123 return ramfs_mknod(dir, dentry, mode | S_IFREG, 0);
124 }
126 static int ramfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
127 {
128 struct inode *inode;
129 int error = -ENOSPC;
131 inode = ramfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
132 if (inode) {
133 int l = strlen(symname)+1;
134 error = page_symlink(inode, symname, l);
135 if (!error) {
136 if (dir->i_mode & S_ISGID)
137 inode->i_gid = dir->i_gid;
138 d_instantiate(dentry, inode);
139 dget(dentry);
140 dir->i_mtime = dir->i_ctime = CURRENT_TIME;
141 } else
142 iput(inode);
143 }
144 return error;
145 }
147 static struct inode_operations ramfs_dir_inode_operations = {
148 .create = ramfs_create,
149 .lookup = simple_lookup,
150 .link = simple_link,
151 .unlink = simple_unlink,
152 .symlink = ramfs_symlink,
153 .mkdir = ramfs_mkdir,
154 .rmdir = simple_rmdir,
155 .mknod = ramfs_mknod,
156 .rename = simple_rename,
157 };
159 static struct super_operations ramfs_ops = {
160 .statfs = simple_statfs,
161 .drop_inode = generic_delete_inode,
162 };
164 static int ramfs_fill_super(struct super_block * sb, void * data, int silent)
165 {
166 struct inode * inode;
167 struct dentry * root;
169 sb->s_maxbytes = MAX_LFS_FILESIZE;
170 sb->s_blocksize = PAGE_CACHE_SIZE;
171 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
172 sb->s_magic = RAMFS_MAGIC;
173 sb->s_op = &ramfs_ops;
174 sb->s_time_gran = 1;
175 inode = ramfs_get_inode(sb, S_IFDIR | 0755, 0);
176 if (!inode)
177 return -ENOMEM;
179 root = d_alloc_root(inode);
180 if (!root) {
181 iput(inode);
182 return -ENOMEM;
183 }
184 sb->s_root = root;
185 return 0;
186 }
188 int ramfs_get_sb(struct file_system_type *fs_type,
189 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
190 {
191 return get_sb_nodev(fs_type, flags, data, ramfs_fill_super, mnt);
192 }
194 static int rootfs_get_sb(struct file_system_type *fs_type,
195 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
196 {
197 return get_sb_nodev(fs_type, flags|MS_NOUSER, data, ramfs_fill_super,
198 mnt);
199 }
201 static struct file_system_type ramfs_fs_type = {
202 .name = "ramfs",
203 .get_sb = ramfs_get_sb,
204 .kill_sb = kill_litter_super,
205 };
206 static struct file_system_type rootfs_fs_type = {
207 .name = "rootfs",
208 .get_sb = rootfs_get_sb,
209 .kill_sb = kill_litter_super,
210 };
212 static int __init init_ramfs_fs(void)
213 {
214 return register_filesystem(&ramfs_fs_type);
215 }
217 static void __exit exit_ramfs_fs(void)
218 {
219 unregister_filesystem(&ramfs_fs_type);
220 }
222 module_init(init_ramfs_fs)
223 module_exit(exit_ramfs_fs)
225 int __init init_rootfs(void)
226 {
227 return register_filesystem(&rootfs_fs_type);
228 }
230 MODULE_LICENSE("GPL");