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11#include <linux/cred.h>
12#include <linux/file.h>
13#include <linux/poll.h>
14#include <linux/sched.h>
15#include <linux/init.h>
16#include <linux/fs.h>
17#include <linux/mount.h>
18#include <linux/module.h>
19#include <linux/kernel.h>
20#include <linux/magic.h>
21#include <linux/anon_inodes.h>
22
23#include <linux/uaccess.h>
24
25static struct vfsmount *anon_inode_mnt __read_mostly;
26static struct inode *anon_inode_inode;
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31static char *anon_inodefs_dname(struct dentry *dentry, char *buffer, int buflen)
32{
33 return dynamic_dname(dentry, buffer, buflen, "anon_inode:%s",
34 dentry->d_name.name);
35}
36
37static const struct dentry_operations anon_inodefs_dentry_operations = {
38 .d_dname = anon_inodefs_dname,
39};
40
41static struct dentry *anon_inodefs_mount(struct file_system_type *fs_type,
42 int flags, const char *dev_name, void *data)
43{
44 return mount_pseudo(fs_type, "anon_inode:", NULL,
45 &anon_inodefs_dentry_operations, ANON_INODE_FS_MAGIC);
46}
47
48static struct file_system_type anon_inode_fs_type = {
49 .name = "anon_inodefs",
50 .mount = anon_inodefs_mount,
51 .kill_sb = kill_anon_super,
52};
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70struct file *anon_inode_getfile(const char *name,
71 const struct file_operations *fops,
72 void *priv, int flags)
73{
74 struct qstr this;
75 struct path path;
76 struct file *file;
77
78 if (IS_ERR(anon_inode_inode))
79 return ERR_PTR(-ENODEV);
80
81 if (fops->owner && !try_module_get(fops->owner))
82 return ERR_PTR(-ENOENT);
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88 file = ERR_PTR(-ENOMEM);
89 this.name = name;
90 this.len = strlen(name);
91 this.hash = 0;
92 path.dentry = d_alloc_pseudo(anon_inode_mnt->mnt_sb, &this);
93 if (!path.dentry)
94 goto err_module;
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96 path.mnt = mntget(anon_inode_mnt);
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101 ihold(anon_inode_inode);
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103 d_instantiate(path.dentry, anon_inode_inode);
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105 file = alloc_file(&path, OPEN_FMODE(flags), fops);
106 if (IS_ERR(file))
107 goto err_dput;
108 file->f_mapping = anon_inode_inode->i_mapping;
109
110 file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
111 file->private_data = priv;
112
113 return file;
114
115err_dput:
116 path_put(&path);
117err_module:
118 module_put(fops->owner);
119 return file;
120}
121EXPORT_SYMBOL_GPL(anon_inode_getfile);
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139int anon_inode_getfd(const char *name, const struct file_operations *fops,
140 void *priv, int flags)
141{
142 int error, fd;
143 struct file *file;
144
145 error = get_unused_fd_flags(flags);
146 if (error < 0)
147 return error;
148 fd = error;
149
150 file = anon_inode_getfile(name, fops, priv, flags);
151 if (IS_ERR(file)) {
152 error = PTR_ERR(file);
153 goto err_put_unused_fd;
154 }
155 fd_install(fd, file);
156
157 return fd;
158
159err_put_unused_fd:
160 put_unused_fd(fd);
161 return error;
162}
163EXPORT_SYMBOL_GPL(anon_inode_getfd);
164
165static int __init anon_inode_init(void)
166{
167 anon_inode_mnt = kern_mount(&anon_inode_fs_type);
168 if (IS_ERR(anon_inode_mnt))
169 panic("anon_inode_init() kernel mount failed (%ld)\n", PTR_ERR(anon_inode_mnt));
170
171 anon_inode_inode = alloc_anon_inode(anon_inode_mnt->mnt_sb);
172 if (IS_ERR(anon_inode_inode))
173 panic("anon_inode_init() inode allocation failed (%ld)\n", PTR_ERR(anon_inode_inode));
174
175 return 0;
176}
177
178fs_initcall(anon_inode_init);
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