File-copy from v4.4.100

This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Please refer to that tree for all history prior to this point.

Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/include/linux/posix_acl_xattr.h b/include/linux/posix_acl_xattr.h
new file mode 100644
index 0000000..6f14ee2
--- /dev/null
+++ b/include/linux/posix_acl_xattr.h
@@ -0,0 +1,75 @@
+/*
+  File: linux/posix_acl_xattr.h
+
+  Extended attribute system call representation of Access Control Lists.
+
+  Copyright (C) 2000 by Andreas Gruenbacher <a.gruenbacher@computer.org>
+  Copyright (C) 2002 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com>
+ */
+#ifndef _POSIX_ACL_XATTR_H
+#define _POSIX_ACL_XATTR_H
+
+#include <linux/posix_acl.h>
+
+/* Extended attribute names */
+#define POSIX_ACL_XATTR_ACCESS	"system.posix_acl_access"
+#define POSIX_ACL_XATTR_DEFAULT	"system.posix_acl_default"
+
+/* Supported ACL a_version fields */
+#define POSIX_ACL_XATTR_VERSION	0x0002
+
+
+/* An undefined entry e_id value */
+#define ACL_UNDEFINED_ID	(-1)
+
+typedef struct {
+	__le16			e_tag;
+	__le16			e_perm;
+	__le32			e_id;
+} posix_acl_xattr_entry;
+
+typedef struct {
+	__le32			a_version;
+	posix_acl_xattr_entry	a_entries[0];
+} posix_acl_xattr_header;
+
+
+static inline size_t
+posix_acl_xattr_size(int count)
+{
+	return (sizeof(posix_acl_xattr_header) +
+		(count * sizeof(posix_acl_xattr_entry)));
+}
+
+static inline int
+posix_acl_xattr_count(size_t size)
+{
+	if (size < sizeof(posix_acl_xattr_header))
+		return -1;
+	size -= sizeof(posix_acl_xattr_header);
+	if (size % sizeof(posix_acl_xattr_entry))
+		return -1;
+	return size / sizeof(posix_acl_xattr_entry);
+}
+
+#ifdef CONFIG_FS_POSIX_ACL
+void posix_acl_fix_xattr_from_user(void *value, size_t size);
+void posix_acl_fix_xattr_to_user(void *value, size_t size);
+#else
+static inline void posix_acl_fix_xattr_from_user(void *value, size_t size)
+{
+}
+static inline void posix_acl_fix_xattr_to_user(void *value, size_t size)
+{
+}
+#endif
+
+struct posix_acl *posix_acl_from_xattr(struct user_namespace *user_ns, 
+				       const void *value, size_t size);
+int posix_acl_to_xattr(struct user_namespace *user_ns,
+		       const struct posix_acl *acl, void *buffer, size_t size);
+
+extern const struct xattr_handler posix_acl_access_xattr_handler;
+extern const struct xattr_handler posix_acl_default_xattr_handler;
+
+#endif	/* _POSIX_ACL_XATTR_H */