1 files changed, 143 insertions, 126 deletions

diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index de402fa915f..aecb15f8455 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -1,76 +1,83 @@
 /*
- * 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 <linux/mutex.h>
+#include <linux/security.h>
 
 #include "sysfs.h"
 
-static int object_depth(struct kobject * kobj)
+static int sysfs_do_create_link_sd(struct kernfs_node *parent,
+				   struct kobject *target_kobj,
+				   const char *name, int warn)
 {
-	struct kobject * p = kobj;
-	int depth = 0;
-	do { depth++; } while ((p = p->parent));
-	return depth;
-}
+	struct kernfs_node *kn, *target = NULL;
+
+	BUG_ON(!name || !parent);
+
+	/*
+	 * We don't own @target_kobj and it may be removed at any time.
+	 * Synchronize using sysfs_symlink_target_lock.  See
+	 * sysfs_remove_dir() for details.
+	 */
+	spin_lock(&sysfs_symlink_target_lock);
+	if (target_kobj->sd) {
+		target = target_kobj->sd;
+		kernfs_get(target);
+	}
+	spin_unlock(&sysfs_symlink_target_lock);
 
-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;
-}
+	if (!target)
+		return -ENOENT;
 
-static void fill_object_path(struct kobject * kobj, char * buffer, int length)
-{
-	struct kobject * p;
+	kn = kernfs_create_link(parent, name, target);
+	kernfs_put(target);
 
-	--length;
-	for (p = kobj; p; p = p->parent) {
-		int cur = strlen(kobject_name(p));
+	if (!IS_ERR(kn))
+		return 0;
 
-		/* back up enough to print this bus id with '/' */
-		length -= cur;
-		strncpy(buffer + length,kobject_name(p),cur);
-		*(buffer + --length) = '/';
-	}
+	if (warn && PTR_ERR(kn) == -EEXIST)
+		sysfs_warn_dup(parent, name);
+	return PTR_ERR(kn);
 }
 
-static int sysfs_add_link(struct dentry * parent, const char * name, struct kobject * target)
+/**
+ *	sysfs_create_link_sd - create symlink to a given object.
+ *	@kn:		directory we're creating the link in.
+ *	@target:	object we're pointing to.
+ *	@name:		name of the symlink.
+ */
+int sysfs_create_link_sd(struct kernfs_node *kn, struct kobject *target,
+			 const char *name)
 {
-	struct sysfs_dirent * parent_sd = parent->d_fsdata;
-	struct sysfs_symlink * sl;
-	int error = 0;
-
-	error = -ENOMEM;
-	sl = kmalloc(sizeof(*sl), GFP_KERNEL);
-	if (!sl)
-		goto exit1;
+	return sysfs_do_create_link_sd(kn, target, name, 1);
+}
 
-	sl->link_name = kmalloc(strlen(name) + 1, GFP_KERNEL);
-	if (!sl->link_name)
-		goto exit2;
+static int sysfs_do_create_link(struct kobject *kobj, struct kobject *target,
+				const char *name, int warn)
+{
+	struct kernfs_node *parent = NULL;
 
-	strcpy(sl->link_name, name);
-	sl->target_kobj = kobject_get(target);
+	if (!kobj)
+		parent = sysfs_root_kn;
+	else
+		parent = kobj->sd;
 
-	error = sysfs_make_dirent(parent_sd, NULL, sl, S_IFLNK|S_IRWXUGO,
-				SYSFS_KOBJ_LINK);
-	if (!error)
-		return 0;
+	if (!parent)
+		return -EFAULT;
 
-	kfree(sl->link_name);
-exit2:
-	kfree(sl);
-exit1:
-	return error;
+	return sysfs_do_create_link_sd(parent, target, name, warn);
 }
 
 /**
@@ -79,102 +86,112 @@ exit1:
  *	@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);
-
-	down(&dentry->d_inode->i_sem);
-	error = sysfs_add_link(dentry, name, target);
-	up(&dentry->d_inode->i_sem);
-	return error;
+	return sysfs_do_create_link(kobj, target, name, 1);
 }
+EXPORT_SYMBOL_GPL(sysfs_create_link);
 
+/**
+ *	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 sysfs_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.
+ *	sysfs_delete_link - remove symlink in object's directory.
  *	@kobj:	object we're acting for.
+ *	@targ:	object we're pointing to.
  *	@name:	name of the symlink to remove.
+ *
+ *	Unlike sysfs_remove_link sysfs_delete_link has enough information
+ *	to successfully delete symlinks in tagged directories.
  */
-
-void sysfs_remove_link(struct kobject * kobj, const char * name)
+void sysfs_delete_link(struct kobject *kobj, struct kobject *targ,
+			const char *name)
 {
-	sysfs_hash_and_remove(kobj->dentry,name);
+	const void *ns = NULL;
+
+	/*
+	 * We don't own @target and it may be removed at any time.
+	 * Synchronize using sysfs_symlink_target_lock.  See
+	 * sysfs_remove_dir() for details.
+	 */
+	spin_lock(&sysfs_symlink_target_lock);
+	if (targ->sd && kernfs_ns_enabled(kobj->sd))
+		ns = targ->sd->ns;
+	spin_unlock(&sysfs_symlink_target_lock);
+	kernfs_remove_by_name_ns(kobj->sd, name, ns);
 }
 
-static int sysfs_get_target_path(struct kobject * kobj, struct kobject * target,
-				 char *path)
+/**
+ *	sysfs_remove_link - remove symlink in object's directory.
+ *	@kobj:	object we're acting for.
+ *	@name:	name of the symlink to remove.
+ */
+void sysfs_remove_link(struct kobject *kobj, const char *name)
 {
-	char * s;
-	int depth, size;
+	struct kernfs_node *parent = NULL;
 
-	depth = object_depth(kobj);
-	size = object_path_length(target) + depth * 3 - 1;
-	if (size > PATH_MAX)
-		return -ENAMETOOLONG;
-
-	pr_debug("%s: depth = %d, size = %d\n", __FUNCTION__, depth, size);
-
-	for (s = path; depth--; s += 3)
-		strcpy(s,"../");
-
-	fill_object_path(target, path, size);
-	pr_debug("%s: path = '%s'\n", __FUNCTION__, path);
+	if (!kobj)
+		parent = sysfs_root_kn;
+	else
+		parent = kobj->sd;
 
-	return 0;
+	kernfs_remove_by_name(parent, name);
 }
+EXPORT_SYMBOL_GPL(sysfs_remove_link);
 
-static int sysfs_getlink(struct dentry *dentry, char * path)
+/**
+ *	sysfs_rename_link_ns - 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.
+ *	@new_ns: new namespace of the symlink.
+ *
+ *	A helper function for the common rename symlink idiom.
+ */
+int sysfs_rename_link_ns(struct kobject *kobj, struct kobject *targ,
+			 const char *old, const char *new, const void *new_ns)
 {
-	struct kobject *kobj, *target_kobj;
-	int error = 0;
+	struct kernfs_node *parent, *kn = NULL;
+	const void *old_ns = NULL;
+	int result;
 
-	kobj = sysfs_get_kobject(dentry->d_parent);
 	if (!kobj)
-		return -EINVAL;
+		parent = sysfs_root_kn;
+	else
+		parent = kobj->sd;
 
-	target_kobj = sysfs_get_kobject(dentry);
-	if (!target_kobj) {
-		kobject_put(kobj);
-		return -EINVAL;
-	}
+	if (targ->sd)
+		old_ns = targ->sd->ns;
 
-	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;
+	result = -ENOENT;
+	kn = kernfs_find_and_get_ns(parent, old, old_ns);
+	if (!kn)
+		goto out;
 
-}
+	result = -EINVAL;
+	if (kernfs_type(kn) != KERNFS_LINK)
+		goto out;
+	if (kn->symlink.target_kn->priv != targ)
+		goto out;
 
-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); 
-	nd_set_link(nd, error ? ERR_PTR(error) : (char *)page);
-	return NULL;
-}
+	result = kernfs_rename_ns(kn, parent, new, new_ns);
 
-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);
+out:
+	kernfs_put(kn);
+	return result;
 }
-
-struct inode_operations sysfs_symlink_inode_operations = {
-	.readlink = generic_readlink,
-	.follow_link = sysfs_follow_link,
-	.put_link = sysfs_put_link,
-};
-
-
-EXPORT_SYMBOL_GPL(sysfs_create_link);
-EXPORT_SYMBOL_GPL(sysfs_remove_link);
-
+EXPORT_SYMBOL_GPL(sysfs_rename_link_ns);