-
-static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
- struct sysfs_dirent *target_sd, char *path)
-{
- struct sysfs_dirent *base, *sd;
- char *s = path;
- int len = 0;
-
- /* go up to the root, stop at the base */
- base = parent_sd;
- while (base->s_parent) {
- sd = target_sd->s_parent;
- while (sd->s_parent && base != sd)
- sd = sd->s_parent;
-
- if (base == sd)
- break;
-
- strcpy(s, "../");
- s += 3;
- base = base->s_parent;
- }
-
- /* determine end of target string for reverse fillup */
- sd = target_sd;
- while (sd->s_parent && sd != base) {
- len += strlen(sd->s_name) + 1;
- sd = sd->s_parent;
- }
-
- /* check limits */
- if (len < 2)
- return -EINVAL;
- len--;
- if ((s - path) + len > PATH_MAX)
- return -ENAMETOOLONG;
-
- /* reverse fillup of target string from target to base */
- sd = target_sd;
- while (sd->s_parent && sd != base) {
- int slen = strlen(sd->s_name);
-
- len -= slen;
- strncpy(s + len, sd->s_name, slen);
- if (len)
- s[--len] = '/';
-
- sd = sd->s_parent;
- }
-
- return 0;
-}
-
-static int sysfs_getlink(struct dentry *dentry, char *path)
-{
- struct sysfs_dirent *sd = dentry->d_fsdata;
- struct sysfs_dirent *parent_sd = sd->s_parent;
- struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
- int error;
-
- mutex_lock(&sysfs_mutex);
- error = sysfs_get_target_path(parent_sd, target_sd, path);
- mutex_unlock(&sysfs_mutex);
-
- return error;
-}
-
-static void *sysfs_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
- int error = -ENOMEM;
- unsigned long page = get_zeroed_page(GFP_KERNEL);
- if (page) {
- error = sysfs_getlink(dentry, (char *) page);
- if (error < 0)
- free_page((unsigned long)page);
- }
- nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
- return NULL;
-}
-
-static void sysfs_put_link(struct dentry *dentry, struct nameidata *nd,
- void *cookie)
-{
- char *page = nd_get_link(nd);
- if (!IS_ERR(page))
- free_page((unsigned long)page);
-}
-
-const struct inode_operations sysfs_symlink_inode_operations = {
- .setxattr = sysfs_setxattr,
- .readlink = generic_readlink,
- .follow_link = sysfs_follow_link,
- .put_link = sysfs_put_link,
- .setattr = sysfs_setattr,
- .getattr = sysfs_getattr,
- .permission = sysfs_permission,
-};