/*
- * symlink.c - operations for sysfs symlinks.
+ * fs/sysfs/symlink.c - sysfs symlink implementation
+ *
+ * Copyright (c) 2001-3 Patrick Mochel
+ * Copyright (c) 2007 SUSE Linux Products GmbH
+ * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
+ *
+ * This file is released under the GPLv2.
+ *
+ * Please see Documentation/filesystems/sysfs.txt for more information.
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/namei.h>
-#include <asm/semaphore.h>
+#include <linux/mutex.h>
#include "sysfs.h"
-static int object_depth(struct sysfs_dirent *sd)
-{
- int depth = 0;
-
- for (; sd->s_parent; sd = sd->s_parent)
- depth++;
-
- return depth;
-}
-
-static int object_path_length(struct sysfs_dirent * sd)
-{
- int length = 1;
-
- for (; sd->s_parent; sd = sd->s_parent)
- length += strlen(sd->s_name) + 1;
-
- return length;
-}
-
-static void fill_object_path(struct sysfs_dirent *sd, char *buffer, int length)
-{
- --length;
- for (; sd->s_parent; sd = sd->s_parent) {
- int cur = strlen(sd->s_name);
-
- /* back up enough to print this bus id with '/' */
- length -= cur;
- strncpy(buffer + length, sd->s_name, cur);
- *(buffer + --length) = '/';
- }
-}
-
-/**
- * sysfs_create_link - create symlink between two objects.
- * @kobj: object whose directory we're creating the link in.
- * @target: object we're pointing to.
- * @name: name of the symlink.
- */
-int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name)
+static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
+ const char *name, int warn)
{
struct sysfs_dirent *parent_sd = NULL;
struct sysfs_dirent *target_sd = NULL;
BUG_ON(!name);
- if (!kobj) {
- if (sysfs_mount && sysfs_mount->mnt_sb)
- parent_sd = sysfs_mount->mnt_sb->s_root->d_fsdata;
- } else
+ if (!kobj)
+ parent_sd = &sysfs_root;
+ else
parent_sd = kobj->sd;
error = -EFAULT;
if (!sd)
goto out_put;
- sd->s_elem.symlink.target_sd = target_sd;
+ sd->s_symlink.target_sd = target_sd;
target_sd = NULL; /* reference is now owned by the symlink */
sysfs_addrm_start(&acxt, parent_sd);
+ if (warn)
+ error = sysfs_add_one(&acxt, sd);
+ else
+ error = __sysfs_add_one(&acxt, sd);
+ sysfs_addrm_finish(&acxt);
- if (!sysfs_find_dirent(parent_sd, name)) {
- sysfs_add_one(&acxt, sd);
- sysfs_link_sibling(sd);
- }
-
- if (!sysfs_addrm_finish(&acxt)) {
- error = -EEXIST;
+ if (error)
goto out_put;
- }
return 0;
return error;
}
+/**
+ * sysfs_create_link - create symlink between two objects.
+ * @kobj: object whose directory we're creating the link in.
+ * @target: object we're pointing to.
+ * @name: name of the symlink.
+ */
+int sysfs_create_link(struct kobject *kobj, struct kobject *target,
+ const char *name)
+{
+ return sysfs_do_create_link(kobj, target, name, 1);
+}
+
+/**
+ * sysfs_create_link_nowarn - create symlink between two objects.
+ * @kobj: object whose directory we're creating the link in.
+ * @target: object we're pointing to.
+ * @name: name of the symlink.
+ *
+ * This function does the same as sysf_create_link(), but it
+ * doesn't warn if the link already exists.
+ */
+int sysfs_create_link_nowarn(struct kobject *kobj, struct kobject *target,
+ const char *name)
+{
+ return sysfs_do_create_link(kobj, target, name, 0);
+}
/**
* sysfs_remove_link - remove symlink in object's directory.
void sysfs_remove_link(struct kobject * kobj, const char * name)
{
- sysfs_hash_and_remove(kobj->sd, name);
+ struct sysfs_dirent *parent_sd = NULL;
+
+ if (!kobj)
+ parent_sd = &sysfs_root;
+ else
+ parent_sd = kobj->sd;
+
+ sysfs_hash_and_remove(parent_sd, name);
}
-static int sysfs_get_target_path(struct sysfs_dirent * parent_sd,
- struct sysfs_dirent * target_sd, char *path)
+static int sysfs_get_target_path(struct sysfs_dirent *parent_sd,
+ struct sysfs_dirent *target_sd, char *path)
{
- char * s;
- int depth, size;
+ 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;
+ }
- depth = object_depth(parent_sd);
- size = object_path_length(target_sd) + depth * 3 - 1;
- if (size > PATH_MAX)
+ /* 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;
- pr_debug("%s: depth = %d, size = %d\n", __FUNCTION__, depth, size);
+ /* reverse fillup of target string from target to base */
+ sd = target_sd;
+ while (sd->s_parent && sd != base) {
+ int slen = strlen(sd->s_name);
- for (s = path; depth--; s += 3)
- strcpy(s,"../");
+ len -= slen;
+ strncpy(s + len, sd->s_name, slen);
+ if (len)
+ s[--len] = '/';
- fill_object_path(target_sd, path, size);
- pr_debug("%s: path = '%s'\n", __FUNCTION__, path);
+ sd = sd->s_parent;
+ }
return 0;
}
{
struct sysfs_dirent *sd = dentry->d_fsdata;
struct sysfs_dirent *parent_sd = sd->s_parent;
- struct sysfs_dirent *target_sd = sd->s_elem.symlink.target_sd;
+ struct sysfs_dirent *target_sd = sd->s_symlink.target_sd;
int error;
mutex_lock(&sysfs_mutex);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff