LXR linux-bk/fs/bad

   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/time.h>
  12#include <linux/smp_lock.h>
  13
  14/*
  15 * The follow_link operation is special: it must behave as a no-op
  16 * so that a bad root inode can at least be unmounted. To do this
  17 * we must dput() the base and return the dentry with a dget().
  18 */
  19static int bad_follow_link(struct dentry *dent, struct nameidata *nd)
  20{
  21        return vfs_follow_link(nd, ERR_PTR(-EIO));
  22}
  23
  24static int return_EIO(void)
  25{
  26        return -EIO;
  27}
  28
  29#define EIO_ERROR ((void *) (return_EIO))
  30
  31static 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
  48struct 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        .getattr        = 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 
  76/**
  77 *      make_bad_inode - mark an inode bad due to an I/O error
  78 *      @inode: Inode to mark bad
  79 *
  80 *      When an inode cannot be read due to a media or remote network
  81 *      failure this function makes the inode "bad" and causes I/O operations
  82 *      on it to fail from this point on.
  83 */
  84 
  85void make_bad_inode(struct inode * inode) 
  86{
  87        inode->i_mode = S_IFREG;
  88        inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  89        inode->i_op = &bad_inode_ops;   
  90        inode->i_fop = &bad_file_ops;   
  91}
  92
  93/*
  94 * This tests whether an inode has been flagged as bad. The test uses
  95 * &bad_inode_ops to cover the case of invalidated inodes as well as
  96 * those created by make_bad_inode() above.
  97 */
  98 
  99/**
 100 *      is_bad_inode - is an inode errored
 101 *      @inode: inode to test
 102 *
 103 *      Returns true if the inode in question has been marked as bad.
 104 */
 105 
 106int is_bad_inode(struct inode * inode) 
 107{
 108        return (inode->i_op == &bad_inode_ops); 
 109}
 110