LXR linux-old/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/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 */
  18static int bad_follow_link(struct dentry *dent, struct nameidata *nd)
  19{
  20        return vfs_follow_link(nd, ERR_PTR(-EIO));
  21}
  22
  23static int return_EIO(void)
  24{
  25        return -EIO;
  26}
  27
  28#define EIO_ERROR ((void *) (return_EIO))
  29
  30static struct file_operations bad_file_ops =
  31{
  32        llseek:         EIO_ERROR,
  33        read:           EIO_ERROR,
  34        write:          EIO_ERROR,
  35        readdir:        EIO_ERROR,
  36        poll:           EIO_ERROR,
  37        ioctl:          EIO_ERROR,
  38        mmap:           EIO_ERROR,
  39        open:           EIO_ERROR,
  40        flush:          EIO_ERROR,
  41        release:        EIO_ERROR,
  42        fsync:          EIO_ERROR,
  43        fasync:         EIO_ERROR,
  44        lock:           EIO_ERROR,
  45};
  46
  47struct inode_operations bad_inode_ops =
  48{
  49        create:         EIO_ERROR,
  50        lookup:         EIO_ERROR,
  51        link:           EIO_ERROR,
  52        unlink:         EIO_ERROR,
  53        symlink:        EIO_ERROR,
  54        mkdir:          EIO_ERROR,
  55        rmdir:          EIO_ERROR,
  56        mknod:          EIO_ERROR,
  57        rename:         EIO_ERROR,
  58        readlink:       EIO_ERROR,
  59        follow_link:    bad_follow_link,
  60        truncate:       EIO_ERROR,
  61        permission:     EIO_ERROR,
  62        revalidate:     EIO_ERROR,
  63};
  64
  65
  66/*
  67 * When a filesystem is unable to read an inode due to an I/O error in
  68 * its read_inode() function, it can call make_bad_inode() to return a
  69 * set of stubs which will return EIO errors as required. 
  70 *
  71 * We only need to do limited initialisation: all other fields are
  72 * preinitialised to zero automatically.
  73 */
  74 
  75/**
  76 *      make_bad_inode - mark an inode bad due to an I/O error
  77 *      @inode: Inode to mark bad
  78 *
  79 *      When an inode cannot be read due to a media or remote network
  80 *      failure this function makes the inode "bad" and causes I/O operations
  81 *      on it to fail from this point on.
  82 */
  83 
  84void make_bad_inode(struct inode * inode) 
  85{
  86        inode->i_mode = S_IFREG;
  87        inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  88        inode->i_op = &bad_inode_ops;   
  89        inode->i_fop = &bad_file_ops;   
  90}
  91
  92/*
  93 * This tests whether an inode has been flagged as bad. The test uses
  94 * &bad_inode_ops to cover the case of invalidated inodes as well as
  95 * those created by make_bad_inode() above.
  96 */
  97 
  98/**
  99 *      is_bad_inode - is an inode errored
 100 *      @inode: inode to test
 101 *
 102 *      Returns true if the inode in question has been marked as bad.
 103 */
 104 
 105int is_bad_inode(struct inode * inode) 
 106{
 107        return (inode->i_op == &bad_inode_ops); 
 108}
 109