/*
- * 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/gfp.h>
+#include <linux/mount.h>
#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/namei.h>
+#include <linux/mutex.h>
+#include <linux/security.h>
#include "sysfs.h"
-static int object_depth(struct kobject * kobj)
+static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
+ const char *name, int warn)
{
- struct kobject * p = kobj;
- int depth = 0;
- do { depth++; } while ((p = p->parent));
- return depth;
-}
+ struct sysfs_dirent *parent_sd = NULL;
+ struct sysfs_dirent *target_sd = NULL;
+ struct sysfs_dirent *sd = NULL;
+ struct sysfs_addrm_cxt acxt;
+ int error;
-static int object_path_length(struct kobject * kobj)
-{
- struct kobject * p = kobj;
- int length = 1;
- do {
- length += strlen(kobject_name(p)) + 1;
- p = p->parent;
- } while (p);
- return length;
-}
+ BUG_ON(!name);
-static void fill_object_path(struct kobject * kobj, char * buffer, int length)
-{
- struct kobject * p;
+ if (!kobj)
+ parent_sd = &sysfs_root;
+ else
+ parent_sd = kobj->sd;
+
+ error = -EFAULT;
+ if (!parent_sd)
+ goto out_put;
+
+ /* target->sd can go away beneath us but is protected with
+ * sysfs_assoc_lock. Fetch target_sd from it.
+ */
+ spin_lock(&sysfs_assoc_lock);
+ if (target->sd)
+ target_sd = sysfs_get(target->sd);
+ spin_unlock(&sysfs_assoc_lock);
+
+ error = -ENOENT;
+ if (!target_sd)
+ goto out_put;
+
+ error = -ENOMEM;
+ sd = sysfs_new_dirent(name, S_IFLNK|S_IRWXUGO, SYSFS_KOBJ_LINK);
+ if (!sd)
+ goto out_put;
- --length;
- for (p = kobj; p; p = p->parent) {
- int cur = strlen(kobject_name(p));
+ sd->s_symlink.target_sd = target_sd;
+ target_sd = NULL; /* reference is now owned by the symlink */
- /* back up enough to print this bus id with '/' */
- length -= cur;
- strncpy(buffer + length,kobject_name(p),cur);
- *(buffer + --length) = '/';
- }
-}
+ 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);
-static int sysfs_add_link(struct dentry * parent, const char * name, struct kobject * target)
-{
- struct sysfs_dirent * parent_sd = parent->d_fsdata;
- struct sysfs_symlink * sl;
- int error = 0;
+ if (error)
+ goto out_put;
- error = -ENOMEM;
- sl = kmalloc(sizeof(*sl), GFP_KERNEL);
- if (!sl)
- goto exit1;
-
- sl->link_name = kmalloc(strlen(name) + 1, GFP_KERNEL);
- if (!sl->link_name)
- goto exit2;
-
- strcpy(sl->link_name, name);
- sl->target_kobj = kobject_get(target);
-
- error = sysfs_make_dirent(parent_sd, NULL, sl, S_IFLNK|S_IRWXUGO,
- SYSFS_KOBJ_LINK);
- if (!error)
- return 0;
-
- kfree(sl->link_name);
-exit2:
- kfree(sl);
-exit1:
+ return 0;
+
+ out_put:
+ sysfs_put(target_sd);
+ sysfs_put(sd);
return error;
}
* @target: object we're pointing to.
* @name: name of the symlink.
*/
-int sysfs_create_link(struct kobject * kobj, struct kobject * target, const char * name)
+int sysfs_create_link(struct kobject *kobj, struct kobject *target,
+ const char *name)
{
- struct dentry * dentry = kobj->dentry;
- int error = 0;
-
- BUG_ON(!kobj || !kobj->dentry || !name);
-
- mutex_lock(&dentry->d_inode->i_mutex);
- error = sysfs_add_link(dentry, name, target);
- mutex_unlock(&dentry->d_inode->i_mutex);
- return error;
+ 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->dentry,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);
+}
+
+/**
+ * sysfs_rename_link - rename symlink in object's directory.
+ * @kobj: object we're acting for.
+ * @targ: object we're pointing to.
+ * @old: previous name of the symlink.
+ * @new: new name of the symlink.
+ *
+ * A helper function for the common rename symlink idiom.
+ */
+int sysfs_rename_link(struct kobject *kobj, struct kobject *targ,
+ const char *old, const char *new)
+{
+ struct sysfs_dirent *parent_sd, *sd = NULL;
+ int result;
+
+ if (!kobj)
+ parent_sd = &sysfs_root;
+ else
+ parent_sd = kobj->sd;
+
+ result = -ENOENT;
+ sd = sysfs_get_dirent(parent_sd, old);
+ if (!sd)
+ goto out;
+
+ result = -EINVAL;
+ if (sysfs_type(sd) != SYSFS_KOBJ_LINK)
+ goto out;
+ if (sd->s_symlink.target_sd->s_dir.kobj != targ)
+ goto out;
+
+ result = sysfs_rename(sd, parent_sd, new);
+
+out:
+ sysfs_put(sd);
+ return result;
}
-static int sysfs_get_target_path(struct kobject * kobj, struct kobject * target,
- 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(kobj);
- size = object_path_length(target) + 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, path, size);
- pr_debug("%s: path = '%s'\n", __FUNCTION__, path);
+ sd = sd->s_parent;
+ }
return 0;
}
static int sysfs_getlink(struct dentry *dentry, char * path)
{
- struct kobject *kobj, *target_kobj;
- int error = 0;
+ 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;
- kobj = sysfs_get_kobject(dentry->d_parent);
- if (!kobj)
- return -EINVAL;
+ mutex_lock(&sysfs_mutex);
+ error = sysfs_get_target_path(parent_sd, target_sd, path);
+ mutex_unlock(&sysfs_mutex);
- target_kobj = sysfs_get_kobject(dentry);
- if (!target_kobj) {
- kobject_put(kobj);
- return -EINVAL;
- }
-
- down_read(&sysfs_rename_sem);
- error = sysfs_get_target_path(kobj, target_kobj, path);
- up_read(&sysfs_rename_sem);
-
- kobject_put(kobj);
- kobject_put(target_kobj);
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)
+ 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;
}
free_page((unsigned long)page);
}
-struct inode_operations sysfs_symlink_inode_operations = {
- .readlink = generic_readlink,
- .follow_link = sysfs_follow_link,
- .put_link = sysfs_put_link,
+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,
};
EXPORT_SYMBOL_GPL(sysfs_create_link);
EXPORT_SYMBOL_GPL(sysfs_remove_link);
+EXPORT_SYMBOL_GPL(sysfs_rename_link);
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff