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         EIO_ERROR,              /* lseek */
  34         EIO_ERROR,              /* read */
  35         EIO_ERROR,              /* write */
  36         EIO_ERROR,              /* readdir */
  37         EIO_ERROR,              /* select */
  38         EIO_ERROR,              /* ioctl */
  39         EIO_ERROR,              /* mmap */
  40         EIO_ERROR,              /* open */
  41         EIO_ERROR,              /* flush */
  42         EIO_ERROR,              /* release */
  43         EIO_ERROR,              /* fsync */
  44         EIO_ERROR,              /* fasync */
  45         EIO_ERROR,              /* check_media_change */
  46         EIO_ERROR               /* revalidate */
  47 };
  48
  49 struct inode_operations bad_inode_ops =
  50 {
  51         &bad_file_ops,          /* default file operations */
  52         EIO_ERROR,              /* create */
  53         EIO_ERROR,              /* lookup */
  54         EIO_ERROR,              /* link */
  55         EIO_ERROR,              /* unlink */
  56         EIO_ERROR,              /* symlink */
  57         EIO_ERROR,              /* mkdir */
  58         EIO_ERROR,              /* rmdir */
  59         EIO_ERROR,              /* mknod */
  60         EIO_ERROR,              /* rename */
  61         EIO_ERROR,              /* readlink */
  62         bad_follow_link,        /* follow_link */
  63         EIO_ERROR,              /* readpage */
  64         EIO_ERROR,              /* writepage */
  65         EIO_ERROR,              /* bmap */
  66         EIO_ERROR,              /* truncate */
  67         EIO_ERROR,              /* permission */
  68         EIO_ERROR,              /* smap */
  69         EIO_ERROR,              /* update_page */
  70         EIO_ERROR               /* revalidate */
  71 };
  72
  73
  74 /*
  75  * When a filesystem is unable to read an inode due to an I/O error in
  76  * its read_inode() function, it can call make_bad_inode() to return a
  77  * set of stubs which will return EIO errors as required.
  78  *
  79  * We only need to do limited initialisation: all other fields are
  80  * preinitialised to zero automatically.
  81  */
  82 void make_bad_inode(struct inode * inode)
  83 {
  84         inode->i_mode = S_IFREG;
  85         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
  86         inode->i_op = &bad_inode_ops;
  87 }
  88
  89 /*
  90  * This tests whether an inode has been flagged as bad. The test uses
  91  * &bad_inode_ops to cover the case of invalidated inodes as well as
  92  * those created by make_bad_inode() above.
  93  */
  94 int is_bad_inode(struct inode * inode)
  95 {
  96         return (inode->i_op == &bad_inode_ops);
  97 }