fs/bad_inode.c

   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 struct dentry * bad_follow_link(struct dentry *dent, struct dentry *base, unsigned int follow)
  19 {
  20         dput(base);
  21         return dget(dent);
  22 }
  23
  24 static int return_EIO(void)
  25 {
  26         return -EIO;
  27 }
  28
  29 #define EIO_ERROR ((void *) (return_EIO))
  30
  31 static struct file_operations bad_file_ops =
  32 {
  33         llseek:         EIO_ERROR,
  34         read:           EIO_ERROR,
  35         write:          EIO_ERROR,
  36         readdir:        EIO_ERROR,
  37         poll:           EIO_ERROR,
  38         ioctl:          EIO_ERROR,
  39         mmap:           EIO_ERROR,
  40         open:           EIO_ERROR,
  41         flush:          EIO_ERROR,
  42         release:        EIO_ERROR,
  43         fsync:          EIO_ERROR,
  44         fasync:         EIO_ERROR,
  45         lock:           EIO_ERROR,
  46 };
  47
  48 struct inode_operations bad_inode_ops =
  49 {
  50         create:         EIO_ERROR,
  51         lookup:         EIO_ERROR,
  52         link:           EIO_ERROR,
  53         unlink:         EIO_ERROR,
  54         symlink:        EIO_ERROR,
  55         mkdir:          EIO_ERROR,
  56         rmdir:          EIO_ERROR,
  57         mknod:          EIO_ERROR,
  58         rename:         EIO_ERROR,
  59         readlink:       EIO_ERROR,
  60         follow_link:    bad_follow_link,
  61         truncate:       EIO_ERROR,
  62         permission:     EIO_ERROR,
  63         revalidate:     EIO_ERROR,
  64 };
  65
  66
  67 /*
  68  * When a filesystem is unable to read an inode due to an I/O error in
  69  * its read_inode() function, it can call make_bad_inode() to return a
  70  * set of stubs which will return EIO errors as required.
  71  *
  72  * We only need to do limited initialisation: all other fields are
  73  * preinitialised to zero automatically.
  74  */
  75 void make_bad_inode(struct inode * inode)
  76 {
  77         inode->i_mode = S_IFREG;
  78         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  79         inode->i_op = &bad_inode_ops;
  80         inode->i_fop = &bad_file_ops;
  81 }
  82
  83 /*
  84  * This tests whether an inode has been flagged as bad. The test uses
  85  * &bad_inode_ops to cover the case of invalidated inodes as well as
  86  * those created by make_bad_inode() above.
  87  */
  88 int is_bad_inode(struct inode * inode)
  89 {
  90         return (inode->i_op == &bad_inode_ops);
  91 }