1 /*
2 * linux/fs/bad_inode.c
3 *
4 * Copyright (C) 1997, Stephen Tweedie
5 *
6 * Provide stub functions for unreadable inodes
7 */
8
9 #include <linux/fs.h>
10 #include <linux/stat.h>
11 #include <linux/sched.h>
12
13 /*
14 * The follow_link operation is special: it must behave as a no-op
15 * so that a bad root inode can at least be unmounted. To do this
16 * we must dput() the base and return the dentry with a dget().
17 */
18 static int bad_follow_link(struct dentry *dent, struct nameidata *nd)
19 {
20 dput(nd->dentry);
21 nd->dentry = dget(dent);
22 return 0;
23 }
24
25 static int return_EIO(void)
26 {
27 return -EIO;
28 }
29
30 #define EIO_ERROR ((void *) (return_EIO))
31
32 static struct file_operations bad_file_ops =
33 {
34 llseek: EIO_ERROR,
35 read: EIO_ERROR,
36 write: EIO_ERROR,
37 readdir: EIO_ERROR,
38 poll: EIO_ERROR,
39 ioctl: EIO_ERROR,
40 mmap: EIO_ERROR,
41 open: EIO_ERROR,
42 flush: EIO_ERROR,
43 release: EIO_ERROR,
44 fsync: EIO_ERROR,
45 fasync: EIO_ERROR,
46 lock: EIO_ERROR,
47 };
48
49 struct inode_operations bad_inode_ops =
50 {
51 create: EIO_ERROR,
52 lookup: EIO_ERROR,
53 link: EIO_ERROR,
54 unlink: EIO_ERROR,
55 symlink: EIO_ERROR,
56 mkdir: EIO_ERROR,
57 rmdir: EIO_ERROR,
58 mknod: EIO_ERROR,
59 rename: EIO_ERROR,
60 readlink: EIO_ERROR,
61 follow_link: bad_follow_link,
62 truncate: EIO_ERROR,
63 permission: EIO_ERROR,
64 revalidate: EIO_ERROR,
65 };
66
67
68 /*
69 * When a filesystem is unable to read an inode due to an I/O error in
70 * its read_inode() function, it can call make_bad_inode() to return a
71 * set of stubs which will return EIO errors as required.
72 *
73 * We only need to do limited initialisation: all other fields are
74 * preinitialised to zero automatically.
75 */
76
77 /**
78 * make_bad_inode - mark an inode bad due to an I/O error
79 * @inode: Inode to mark bad
80 *
81 * When an inode cannot be read due to a media or remote network
82 * failure this function makes the inode "bad" and causes I/O operations
83 * on it to fail from this point on.
84 */
85
86 void make_bad_inode(struct inode * inode)
87 {
88 inode->i_mode = S_IFREG;
89 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
90 inode->i_op = &bad_inode_ops;
91 inode->i_fop = &bad_file_ops;
92 }
93
94 /*
95 * This tests whether an inode has been flagged as bad. The test uses
96 * &bad_inode_ops to cover the case of invalidated inodes as well as
97 * those created by make_bad_inode() above.
98 */
99
100 /**
101 * is_bad_inode - is an inode errored
102 * @inode: inode to test
103 *
104 * Returns true if the inode in question has been marked as bad.
105 */
106
107 int is_bad_inode(struct inode * inode)
108 {
109 return (inode->i_op == &bad_inode_ops);
110 }
111
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