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       1                 :            : /*
       2                 :            :  * JFFS2 -- Journalling Flash File System, Version 2.
       3                 :            :  *
       4                 :            :  * Copyright © 2001-2007 Red Hat, Inc.
       5                 :            :  *
       6                 :            :  * Created by David Woodhouse <dwmw2@infradead.org>
       7                 :            :  *
       8                 :            :  * For licensing information, see the file 'LICENCE' in this directory.
       9                 :            :  *
      10                 :            :  */
      11                 :            : 
      12                 :            : #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
      13                 :            : 
      14                 :            : #include <linux/kernel.h>
      15                 :            : #include <linux/fs.h>
      16                 :            : #include <linux/namei.h>
      17                 :            : #include "nodelist.h"
      18                 :            : 
      19                 :            : static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
      20                 :            : 
      21                 :            : const struct inode_operations jffs2_symlink_inode_operations =
      22                 :            : {
      23                 :            :         .readlink =     generic_readlink,
      24                 :            :         .follow_link =  jffs2_follow_link,
      25                 :            :         .setattr =      jffs2_setattr,
      26                 :            :         .setxattr =     jffs2_setxattr,
      27                 :            :         .getxattr =     jffs2_getxattr,
      28                 :            :         .listxattr =    jffs2_listxattr,
      29                 :            :         .removexattr =  jffs2_removexattr
      30                 :            : };
      31                 :            : 
      32                 :          0 : static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd)
      33                 :            : {
      34                 :          0 :         struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
      35                 :          0 :         char *p = (char *)f->target;
      36                 :            : 
      37                 :            :         /*
      38                 :            :          * We don't acquire the f->sem mutex here since the only data we
      39                 :            :          * use is f->target.
      40                 :            :          *
      41                 :            :          * 1. If we are here the inode has already built and f->target has
      42                 :            :          * to point to the target path.
      43                 :            :          * 2. Nobody uses f->target (if the inode is symlink's inode). The
      44                 :            :          * exception is inode freeing function which frees f->target. But
      45                 :            :          * it can't be called while we are here and before VFS has
      46                 :            :          * stopped using our f->target string which we provide by means of
      47                 :            :          * nd_set_link() call.
      48                 :            :          */
      49                 :            : 
      50         [ #  # ]:          0 :         if (!p) {
      51                 :          0 :                 pr_err("%s(): can't find symlink target\n", __func__);
      52                 :            :                 p = ERR_PTR(-EIO);
      53                 :            :         }
      54                 :            :         jffs2_dbg(1, "%s(): target path is '%s'\n",
      55                 :            :                   __func__, (char *)f->target);
      56                 :            : 
      57                 :            :         nd_set_link(nd, p);
      58                 :            : 
      59                 :            :         /*
      60                 :            :          * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe
      61                 :            :          * since the only way that may cause f->target to be changed is iput() operation.
      62                 :            :          * But VFS will not use f->target after iput() has been called.
      63                 :            :          */
      64                 :          0 :         return NULL;
      65                 :            : }
      66                 :            :