root/fs/jffs2/symlink.c

DEFINITIONS

1. jffs2_follow_link

/*
 * 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.
 *
 */

#include <linux/kernel.h>
#include <linux/slab.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,
        .permission =   jffs2_permission,
        .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) {
                printk(KERN_ERR "jffs2_follow_link(): can't find symlink target\n");
                p = ERR_PTR(-EIO);
        }
        D1(printk(KERN_DEBUG "jffs2_follow_link(): target path is '%s'\n", (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;
}