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kernel/linux-imx6_3.14.28/fs/jffs2/symlink.c 1.82 KB
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  /*
   * JFFS2 -- Journalling Flash File System, Version 2.
   *
   * Copyright © 2001-2007 Red Hat, Inc.
   *
   * Created by David Woodhouse <dwmw2@infradead.org>
   *
   * For licensing information, see the file 'LICENCE' in this directory.
   *
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/kernel.h>
  #include <linux/fs.h>
  #include <linux/namei.h>
  #include "nodelist.h"
  
  static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd);
  
  const struct inode_operations jffs2_symlink_inode_operations =
  {
  	.readlink =	generic_readlink,
  	.follow_link =	jffs2_follow_link,
  	.setattr =	jffs2_setattr,
  	.setxattr =	jffs2_setxattr,
  	.getxattr =	jffs2_getxattr,
  	.listxattr =	jffs2_listxattr,
  	.removexattr =	jffs2_removexattr
  };
  
  static void *jffs2_follow_link(struct dentry *dentry, struct nameidata *nd)
  {
  	struct jffs2_inode_info *f = JFFS2_INODE_INFO(dentry->d_inode);
  	char *p = (char *)f->target;
  
  	/*
  	 * We don't acquire the f->sem mutex here since the only data we
  	 * use is f->target.
  	 *
  	 * 1. If we are here the inode has already built and f->target has
  	 * to point to the target path.
  	 * 2. Nobody uses f->target (if the inode is symlink's inode). The
  	 * exception is inode freeing function which frees f->target. But
  	 * it can't be called while we are here and before VFS has
  	 * stopped using our f->target string which we provide by means of
  	 * nd_set_link() call.
  	 */
  
  	if (!p) {
  		pr_err("%s(): can't find symlink target
  ", __func__);
  		p = ERR_PTR(-EIO);
  	}
  	jffs2_dbg(1, "%s(): target path is '%s'
  ",
  		  __func__, (char *)f->target);
  
  	nd_set_link(nd, p);
  
  	/*
  	 * We will unlock the f->sem mutex but VFS will use the f->target string. This is safe
  	 * since the only way that may cause f->target to be changed is iput() operation.
  	 * But VFS will not use f->target after iput() has been called.
  	 */
  	return NULL;
  }