Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/sysfs/Kconfig b/fs/sysfs/Kconfig
index b275601..b0fe1cc 100644
--- a/fs/sysfs/Kconfig
+++ b/fs/sysfs/Kconfig
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 config SYSFS
 	bool "sysfs file system support" if EXPERT
 	default y
diff --git a/fs/sysfs/Makefile b/fs/sysfs/Makefile
index 6eff6e1..0906b9e 100644
--- a/fs/sysfs/Makefile
+++ b/fs/sysfs/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
 #
 # Makefile for the sysfs virtual filesystem
 #
diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index feeae80..aa85f28 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -43,7 +43,8 @@
 	kuid_t uid;
 	kgid_t gid;
 
-	BUG_ON(!kobj);
+	if (WARN_ON(!kobj))
+		return -EINVAL;
 
 	if (kobj->parent)
 		parent = kobj->parent->sd;
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 0a7252a..130fc6f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -17,7 +17,6 @@
 #include <linux/seq_file.h>
 
 #include "sysfs.h"
-#include "../kernfs/kernfs-internal.h"
 
 /*
  * Determine ktype->sysfs_ops for the given kernfs_node.  This function
@@ -325,7 +324,8 @@
 	kuid_t uid;
 	kgid_t gid;
 
-	BUG_ON(!kobj || !kobj->sd || !attr);
+	if (WARN_ON(!kobj || !kobj->sd || !attr))
+		return -EINVAL;
 
 	kobject_get_ownership(kobj, &uid, &gid);
 	return sysfs_add_file_mode_ns(kobj->sd, attr, false, attr->mode,
@@ -334,7 +334,7 @@
 }
 EXPORT_SYMBOL_GPL(sysfs_create_file_ns);
 
-int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
+int sysfs_create_files(struct kobject *kobj, const struct attribute * const *ptr)
 {
 	int err = 0;
 	int i;
@@ -493,9 +493,10 @@
 	return ret;
 }
 
-void sysfs_remove_files(struct kobject *kobj, const struct attribute **ptr)
+void sysfs_remove_files(struct kobject *kobj, const struct attribute * const *ptr)
 {
 	int i;
+
 	for (i = 0; ptr[i]; i++)
 		sysfs_remove_file(kobj, ptr[i]);
 }
@@ -537,7 +538,8 @@
 	kuid_t uid;
 	kgid_t gid;
 
-	BUG_ON(!kobj || !kobj->sd || !attr);
+	if (WARN_ON(!kobj || !kobj->sd || !attr))
+		return -EINVAL;
 
 	kobject_get_ownership(kobj, &uid, &gid);
 	return sysfs_add_file_mode_ns(kobj->sd, &attr->attr, true,
diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 1eb2d63..d41c21f 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -112,7 +112,8 @@
 	kgid_t gid;
 	int error;
 
-	BUG_ON(!kobj || (!update && !kobj->sd));
+	if (WARN_ON(!kobj || (!update && !kobj->sd)))
+		return -EINVAL;
 
 	/* Updates may happen before the object has been instantiated */
 	if (unlikely(update && !kobj->sd))
@@ -174,6 +175,26 @@
 }
 EXPORT_SYMBOL_GPL(sysfs_create_group);
 
+static int internal_create_groups(struct kobject *kobj, int update,
+				  const struct attribute_group **groups)
+{
+	int error = 0;
+	int i;
+
+	if (!groups)
+		return 0;
+
+	for (i = 0; groups[i]; i++) {
+		error = internal_create_group(kobj, update, groups[i]);
+		if (error) {
+			while (--i >= 0)
+				sysfs_remove_group(kobj, groups[i]);
+			break;
+		}
+	}
+	return error;
+}
+
 /**
  * sysfs_create_groups - given a directory kobject, create a bunch of attribute groups
  * @kobj:	The kobject to create the group on
@@ -190,25 +211,29 @@
 int sysfs_create_groups(struct kobject *kobj,
 			const struct attribute_group **groups)
 {
-	int error = 0;
-	int i;
-
-	if (!groups)
-		return 0;
-
-	for (i = 0; groups[i]; i++) {
-		error = sysfs_create_group(kobj, groups[i]);
-		if (error) {
-			while (--i >= 0)
-				sysfs_remove_group(kobj, groups[i]);
-			break;
-		}
-	}
-	return error;
+	return internal_create_groups(kobj, 0, groups);
 }
 EXPORT_SYMBOL_GPL(sysfs_create_groups);
 
 /**
+ * sysfs_update_groups - given a directory kobject, create a bunch of attribute groups
+ * @kobj:	The kobject to update the group on
+ * @groups:	The attribute groups to update, NULL terminated
+ *
+ * This function update a bunch of attribute groups.  If an error occurs when
+ * updating a group, all previously updated groups will be removed together
+ * with already existing (not updated) attributes.
+ *
+ * Returns 0 on success or error code from sysfs_update_group on failure.
+ */
+int sysfs_update_groups(struct kobject *kobj,
+			const struct attribute_group **groups)
+{
+	return internal_create_groups(kobj, 1, groups);
+}
+EXPORT_SYMBOL_GPL(sysfs_update_groups);
+
+/**
  * sysfs_update_group - given a directory kobject, update an attribute group
  * @kobj:	The kobject to update the group on
  * @grp:	The attribute group to update
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 92682fc..db81cfb 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -13,34 +13,70 @@
 #include <linux/magic.h>
 #include <linux/mount.h>
 #include <linux/init.h>
+#include <linux/slab.h>
 #include <linux/user_namespace.h>
+#include <linux/fs_context.h>
+#include <net/net_namespace.h>
 
 #include "sysfs.h"
 
 static struct kernfs_root *sysfs_root;
 struct kernfs_node *sysfs_root_kn;
 
-static struct dentry *sysfs_mount(struct file_system_type *fs_type,
-	int flags, const char *dev_name, void *data)
+static int sysfs_get_tree(struct fs_context *fc)
 {
-	struct dentry *root;
-	void *ns;
-	bool new_sb = false;
+	struct kernfs_fs_context *kfc = fc->fs_private;
+	int ret;
 
-	if (!(flags & SB_KERNMOUNT)) {
+	ret = kernfs_get_tree(fc);
+	if (ret)
+		return ret;
+
+	if (kfc->new_sb_created)
+		fc->root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE;
+	return 0;
+}
+
+static void sysfs_fs_context_free(struct fs_context *fc)
+{
+	struct kernfs_fs_context *kfc = fc->fs_private;
+
+	if (kfc->ns_tag)
+		kobj_ns_drop(KOBJ_NS_TYPE_NET, kfc->ns_tag);
+	kernfs_free_fs_context(fc);
+	kfree(kfc);
+}
+
+static const struct fs_context_operations sysfs_fs_context_ops = {
+	.free		= sysfs_fs_context_free,
+	.get_tree	= sysfs_get_tree,
+};
+
+static int sysfs_init_fs_context(struct fs_context *fc)
+{
+	struct kernfs_fs_context *kfc;
+	struct net *netns;
+
+	if (!(fc->sb_flags & SB_KERNMOUNT)) {
 		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
-			return ERR_PTR(-EPERM);
+			return -EPERM;
 	}
 
-	ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
-	root = kernfs_mount_ns(fs_type, flags, sysfs_root,
-				SYSFS_MAGIC, &new_sb, ns);
-	if (!new_sb)
-		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
-	else if (!IS_ERR(root))
-		root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE;
+	kfc = kzalloc(sizeof(struct kernfs_fs_context), GFP_KERNEL);
+	if (!kfc)
+		return -ENOMEM;
 
-	return root;
+	kfc->ns_tag = netns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
+	kfc->root = sysfs_root;
+	kfc->magic = SYSFS_MAGIC;
+	fc->fs_private = kfc;
+	fc->ops = &sysfs_fs_context_ops;
+	if (netns) {
+		put_user_ns(fc->user_ns);
+		fc->user_ns = get_user_ns(netns->user_ns);
+	}
+	fc->global = true;
+	return 0;
 }
 
 static void sysfs_kill_sb(struct super_block *sb)
@@ -52,10 +88,10 @@
 }
 
 static struct file_system_type sysfs_fs_type = {
-	.name		= "sysfs",
-	.mount		= sysfs_mount,
-	.kill_sb	= sysfs_kill_sb,
-	.fs_flags	= FS_USERNS_MOUNT,
+	.name			= "sysfs",
+	.init_fs_context	= sysfs_init_fs_context,
+	.kill_sb		= sysfs_kill_sb,
+	.fs_flags		= FS_USERNS_MOUNT,
 };
 
 int __init sysfs_init(void)
diff --git a/fs/sysfs/symlink.c b/fs/sysfs/symlink.c
index 215c225..c4deecc 100644
--- a/fs/sysfs/symlink.c
+++ b/fs/sysfs/symlink.c
@@ -23,7 +23,8 @@
 {
 	struct kernfs_node *kn, *target = NULL;
 
-	BUG_ON(!name || !parent);
+	if (WARN_ON(!name || !parent))
+		return -EINVAL;
 
 	/*
 	 * We don't own @target_kobj and it may be removed at any time.