2.1.11-6.3-compat-idmapped-mount-api-changes.patch

From ecd3ef2b3171e7ce507fd0ad653597d00eab0228 Mon Sep 17 00:00:00 2001
From: Spotlight <spotlight@joscomputing.space>
Date: Wed, 26 Apr 2023 12:56:38 -0500
Subject: [PATCH] Backport "Support idmapped mount for kernel 6.3"

---
 config/kernel-acl.m4                         | 34 ++++++--
 config/kernel-generic_fillattr.m4            | 33 +++++--
 config/kernel-inode-create.m4                | 41 +++++++--
 config/kernel-inode-getattr.m4               | 63 ++++++++++----
 config/kernel-inode-permission.m4            | 35 ++++++--
 config/kernel-inode-setattr.m4               | 87 +++++++++++++++++++
 config/kernel-is_owner_or_cap.m4             | 25 +++++-
 config/kernel-mkdir.m4                       | 55 +++++++++---
 config/kernel-mknod.m4                       | 34 +++++++-
 config/kernel-rename.m4                      | 59 ++++++++++---
 config/kernel-setattr-prepare.m4             | 44 +++++++---
 config/kernel-symlink.m4                     | 33 +++++--
 config/kernel-tmpfile.m4                     | 33 +++++--
 config/kernel-xattr-handler.m4               | 91 +++++++++++++-------
 config/kernel.m4                             |  6 +-
 include/os/freebsd/spl/sys/types.h           |  2 +-
 include/os/freebsd/zfs/sys/zfs_vnops_os.h    | 10 +--
 include/os/linux/kernel/linux/vfs_compat.h   | 21 ++++-
 include/os/linux/kernel/linux/xattr_compat.h | 17 +++-
 include/os/linux/spl/sys/cred.h              | 30 ++++---
 include/os/linux/spl/sys/types.h             | 15 +++-
 include/os/linux/zfs/sys/policy.h            |  6 +-
 include/os/linux/zfs/sys/zfs_vnops_os.h      | 15 ++--
 include/os/linux/zfs/sys/zpl.h               | 13 ++-
 include/sys/zfs_acl.h                        | 12 +--
 module/os/freebsd/zfs/zfs_acl.c              | 10 +--
 module/os/freebsd/zfs/zfs_vnops_os.c         | 10 +--
 module/os/linux/spl/spl-cred.c               | 12 +++
 module/os/linux/zfs/policy.c                 | 13 +--
 module/os/linux/zfs/zfs_acl.c                | 37 ++++----
 module/os/linux/zfs/zfs_dir.c                |  4 +-
 module/os/linux/zfs/zfs_ioctl_os.c           |  4 +
 module/os/linux/zfs/zfs_vnops_os.c           | 35 ++++----
 module/os/linux/zfs/zfs_znode.c              |  2 +-
 module/os/linux/zfs/zpl_ctldir.c             | 61 ++++++++++---
 module/os/linux/zfs/zpl_file.c               | 10 +--
 module/os/linux/zfs/zpl_inode.c              | 79 ++++++++++++-----
 module/os/linux/zfs/zpl_xattr.c              | 25 +++---
 module/zfs/zfs_replay.c                      | 14 +--
 module/zfs/zfs_vnops.c                       |  4 +-
 40 files changed, 848 insertions(+), 286 deletions(-)
 create mode 100644 config/kernel-inode-setattr.m4

diff --git a/config/kernel-acl.m4 b/config/kernel-acl.m4
index 6e92da97d0f..be08c3c6072 100644
--- a/config/kernel-acl.m4
+++ b/config/kernel-acl.m4
@@ -236,7 +236,22 @@ dnl #
 dnl # 6.2 API change,
 dnl # set_acl() second paramter changed to a struct dentry *
 dnl #
+dnl # 6.3 API change,
+dnl # set_acl() first parameter changed to struct mnt_idmap *
+dnl #
 AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_OPERATIONS_SET_ACL], [
+	ZFS_LINUX_TEST_SRC([inode_operations_set_acl_mnt_idmap_dentry], [
+		#include <linux/fs.h>
+
+		int set_acl_fn(struct mnt_idmap *idmap,
+		    struct dentry *dent, struct posix_acl *acl,
+		    int type) { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.set_acl = set_acl_fn,
+		};
+	],[])
 	ZFS_LINUX_TEST_SRC([inode_operations_set_acl_userns_dentry], [
 		#include <linux/fs.h>
 
@@ -281,17 +296,24 @@ AC_DEFUN([ZFS_AC_KERNEL_INODE_OPERATIONS_SET_ACL], [
 		AC_DEFINE(HAVE_SET_ACL, 1, [iops->set_acl() exists])
 		AC_DEFINE(HAVE_SET_ACL_USERNS, 1, [iops->set_acl() takes 4 args])
 	],[
-		ZFS_LINUX_TEST_RESULT([inode_operations_set_acl_userns_dentry], [
+		ZFS_LINUX_TEST_RESULT([inode_operations_set_acl_mnt_idmap_dentry], [
 			AC_MSG_RESULT(yes)
 			AC_DEFINE(HAVE_SET_ACL, 1, [iops->set_acl() exists])
-			AC_DEFINE(HAVE_SET_ACL_USERNS_DENTRY_ARG2, 1,
-			    [iops->set_acl() takes 4 args, arg2 is struct dentry *])
+			AC_DEFINE(HAVE_SET_ACL_IDMAP_DENTRY, 1,
+			    [iops->set_acl() takes 4 args, arg1 is struct mnt_idmap *])
 		],[
-			ZFS_LINUX_TEST_RESULT([inode_operations_set_acl], [
+			ZFS_LINUX_TEST_RESULT([inode_operations_set_acl_userns_dentry], [
 				AC_MSG_RESULT(yes)
-				AC_DEFINE(HAVE_SET_ACL, 1, [iops->set_acl() exists, takes 3 args])
+				AC_DEFINE(HAVE_SET_ACL, 1, [iops->set_acl() exists])
+				AC_DEFINE(HAVE_SET_ACL_USERNS_DENTRY_ARG2, 1,
+				    [iops->set_acl() takes 4 args, arg2 is struct dentry *])
 			],[
-				ZFS_LINUX_REQUIRE_API([i_op->set_acl()], [3.14])
+				ZFS_LINUX_TEST_RESULT([inode_operations_set_acl], [
+					AC_MSG_RESULT(yes)
+					AC_DEFINE(HAVE_SET_ACL, 1, [iops->set_acl() exists, takes 3 args])
+				],[
+					ZFS_LINUX_REQUIRE_API([i_op->set_acl()], [3.14])
+				])
 			])
 		])
 	])
diff --git a/config/kernel-generic_fillattr.m4 b/config/kernel-generic_fillattr.m4
index 0acd5d53103..02dee4d4c00 100644
--- a/config/kernel-generic_fillattr.m4
+++ b/config/kernel-generic_fillattr.m4
@@ -4,7 +4,10 @@ dnl #
 dnl # generic_fillattr in linux/fs.h now requires a struct user_namespace*
 dnl # as the first arg, to support idmapped mounts.
 dnl #
-AC_DEFUN([ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR_USERNS], [
+dnl # 6.3 API
+dnl # generic_fillattr() now takes struct mnt_idmap* as the first argument
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR], [
 	ZFS_LINUX_TEST_SRC([generic_fillattr_userns], [
 		#include <linux/fs.h>
 	],[
@@ -13,16 +16,32 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR_USERNS], [
 		struct kstat *k = NULL;
 		generic_fillattr(userns, in, k);
 	])
+
+	ZFS_LINUX_TEST_SRC([generic_fillattr_mnt_idmap], [
+		#include <linux/fs.h>
+	],[
+		struct mnt_idmap *idmap = NULL;
+		struct inode *in = NULL;
+		struct kstat *k = NULL;
+		generic_fillattr(idmap, in, k);
+	])
 ])
 
-AC_DEFUN([ZFS_AC_KERNEL_GENERIC_FILLATTR_USERNS], [
-	AC_MSG_CHECKING([whether generic_fillattr requires struct user_namespace*])
-	ZFS_LINUX_TEST_RESULT([generic_fillattr_userns], [
+AC_DEFUN([ZFS_AC_KERNEL_GENERIC_FILLATTR], [
+	AC_MSG_CHECKING([whether generic_fillattr requires struct mnt_idmap*])
+	ZFS_LINUX_TEST_RESULT([generic_fillattr_mnt_idmap], [
 		AC_MSG_RESULT([yes])
-		AC_DEFINE(HAVE_GENERIC_FILLATTR_USERNS, 1,
-		    [generic_fillattr requires struct user_namespace*])
+		AC_DEFINE(HAVE_GENERIC_FILLATTR_IDMAP, 1,
+		    [generic_fillattr requires struct mnt_idmap*])
 	],[
-		AC_MSG_RESULT([no])
+		AC_MSG_CHECKING([whether generic_fillattr requires struct user_namespace*])
+		ZFS_LINUX_TEST_RESULT([generic_fillattr_userns], [
+			AC_MSG_RESULT([yes])
+			AC_DEFINE(HAVE_GENERIC_FILLATTR_USERNS, 1,
+			    [generic_fillattr requires struct user_namespace*])
+		],[
+			AC_MSG_RESULT([no])
+		])
 	])
 ])
 
diff --git a/config/kernel-inode-create.m4 b/config/kernel-inode-create.m4
index a6ea11fb61b..9e9e4318097 100644
--- a/config/kernel-inode-create.m4
+++ b/config/kernel-inode-create.m4
@@ -1,4 +1,22 @@
 AC_DEFUN([ZFS_AC_KERNEL_SRC_CREATE], [
+	dnl #
+	dnl # 6.3 API change
+	dnl # The first arg is changed to struct mnt_idmap *
+	dnl #
+	ZFS_LINUX_TEST_SRC([create_mnt_idmap], [
+		#include <linux/fs.h>
+		#include <linux/sched.h>
+
+		int inode_create(struct mnt_idmap *idmap,
+		    struct inode *inode ,struct dentry *dentry,
+		    umode_t umode, bool flag) { return 0; }
+
+		static const struct inode_operations
+			iops __attribute__ ((unused)) = {
+			.create         = inode_create,
+		};
+	],[])
+
 	dnl #
 	dnl # 5.12 API change that added the struct user_namespace* arg
 	dnl # to the front of this function type's arg list.
@@ -35,19 +53,28 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_CREATE], [
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_CREATE], [
-	AC_MSG_CHECKING([whether iops->create() takes struct user_namespace*])
-	ZFS_LINUX_TEST_RESULT([create_userns], [
+	AC_MSG_CHECKING([whether iops->create() takes struct mnt_idmap*])
+	ZFS_LINUX_TEST_RESULT([create_mnt_idmap], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_IOPS_CREATE_USERNS, 1,
-		   [iops->create() takes struct user_namespace*])
+		AC_DEFINE(HAVE_IOPS_CREATE_IDMAP, 1,
+		   [iops->create() takes struct mnt_idmap*])
 	],[
 		AC_MSG_RESULT(no)
 
-		AC_MSG_CHECKING([whether iops->create() passes flags])
-		ZFS_LINUX_TEST_RESULT([create_flags], [
+		AC_MSG_CHECKING([whether iops->create() takes struct user_namespace*])
+		ZFS_LINUX_TEST_RESULT([create_userns], [
 			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_IOPS_CREATE_USERNS, 1,
+			   [iops->create() takes struct user_namespace*])
 		],[
-			ZFS_LINUX_TEST_ERROR([iops->create()])
+			AC_MSG_RESULT(no)
+
+			AC_MSG_CHECKING([whether iops->create() passes flags])
+			ZFS_LINUX_TEST_RESULT([create_flags], [
+				AC_MSG_RESULT(yes)
+			],[
+				ZFS_LINUX_TEST_ERROR([iops->create()])
+			])
 		])
 	])
 ])
diff --git a/config/kernel-inode-getattr.m4 b/config/kernel-inode-getattr.m4
index f62e82f5230..c8bfb07862a 100644
--- a/config/kernel-inode-getattr.m4
+++ b/config/kernel-inode-getattr.m4
@@ -1,4 +1,24 @@
 AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_GETATTR], [
+	dnl #
+	dnl # Linux 6.3 API
+	dnl # The first arg of getattr I/O operations handler type
+	dnl # is changed to struct mnt_idmap*
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_operations_getattr_mnt_idmap], [
+		#include <linux/fs.h>
+
+		int test_getattr(
+		    struct mnt_idmap *idmap,
+		    const struct path *p, struct kstat *k,
+		    u32 request_mask, unsigned int query_flags)
+		    { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.getattr = test_getattr,
+		};
+	],[])
+
 	dnl #
 	dnl # Linux 5.12 API
 	dnl # The getattr I/O operations handler type was extended to require
@@ -55,37 +75,48 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_GETATTR], [
 
 AC_DEFUN([ZFS_AC_KERNEL_INODE_GETATTR], [
 	dnl #
-	dnl # Kernel 5.12 test
+	dnl # Kernel 6.3 test
 	dnl #
-	AC_MSG_CHECKING([whether iops->getattr() takes user_namespace])
-	ZFS_LINUX_TEST_RESULT([inode_operations_getattr_userns], [
+	AC_MSG_CHECKING([whether iops->getattr() takes mnt_idmap])
+	ZFS_LINUX_TEST_RESULT([inode_operations_getattr_mnt_idmap], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_USERNS_IOPS_GETATTR, 1,
-		    [iops->getattr() takes struct user_namespace*])
+		AC_DEFINE(HAVE_IDMAP_IOPS_GETATTR, 1,
+		    [iops->getattr() takes struct mnt_idmap*])
 	],[
 		AC_MSG_RESULT(no)
-
 		dnl #
-		dnl # Kernel 4.11 test
+		dnl # Kernel 5.12 test
 		dnl #
-		AC_MSG_CHECKING([whether iops->getattr() takes a path])
-		ZFS_LINUX_TEST_RESULT([inode_operations_getattr_path], [
+		AC_MSG_CHECKING([whether iops->getattr() takes user_namespace])
+		ZFS_LINUX_TEST_RESULT([inode_operations_getattr_userns], [
 			AC_MSG_RESULT(yes)
-			AC_DEFINE(HAVE_PATH_IOPS_GETATTR, 1,
-				[iops->getattr() takes a path])
+			AC_DEFINE(HAVE_USERNS_IOPS_GETATTR, 1,
+			    [iops->getattr() takes struct user_namespace*])
 		],[
 			AC_MSG_RESULT(no)
 
 			dnl #
-			dnl # Kernel < 4.11 test
+			dnl # Kernel 4.11 test
 			dnl #
-			AC_MSG_CHECKING([whether iops->getattr() takes a vfsmount])
-			ZFS_LINUX_TEST_RESULT([inode_operations_getattr_vfsmount], [
+			AC_MSG_CHECKING([whether iops->getattr() takes a path])
+			ZFS_LINUX_TEST_RESULT([inode_operations_getattr_path], [
 				AC_MSG_RESULT(yes)
-				AC_DEFINE(HAVE_VFSMOUNT_IOPS_GETATTR, 1,
-					[iops->getattr() takes a vfsmount])
+				AC_DEFINE(HAVE_PATH_IOPS_GETATTR, 1,
+					[iops->getattr() takes a path])
 			],[
 				AC_MSG_RESULT(no)
+
+				dnl #
+				dnl # Kernel < 4.11 test
+				dnl #
+				AC_MSG_CHECKING([whether iops->getattr() takes a vfsmount])
+				ZFS_LINUX_TEST_RESULT([inode_operations_getattr_vfsmount], [
+					AC_MSG_RESULT(yes)
+					AC_DEFINE(HAVE_VFSMOUNT_IOPS_GETATTR, 1,
+						[iops->getattr() takes a vfsmount])
+				],[
+					AC_MSG_RESULT(no)
+				])
 			])
 		])
 	])
diff --git a/config/kernel-inode-permission.m4 b/config/kernel-inode-permission.m4
index ba9ff5d43d4..01d23635b0c 100644
--- a/config/kernel-inode-permission.m4
+++ b/config/kernel-inode-permission.m4
@@ -1,4 +1,22 @@
 AC_DEFUN([ZFS_AC_KERNEL_SRC_PERMISSION], [
+	dnl #
+	dnl # 6.3 API change
+	dnl # iops->permission() now takes struct mnt_idmap*
+	dnl # as its first arg
+	dnl #
+	ZFS_LINUX_TEST_SRC([permission_mnt_idmap], [
+		#include <linux/fs.h>
+		#include <linux/sched.h>
+
+		int inode_permission(struct mnt_idmap *idmap,
+		    struct inode *inode, int mask) { return 0; }
+
+		static const struct inode_operations
+			iops __attribute__ ((unused)) = {
+			.permission             = inode_permission,
+		};
+	],[])
+
 	dnl #
 	dnl # 5.12 API change that added the struct user_namespace* arg
 	dnl # to the front of this function type's arg list.
@@ -18,12 +36,19 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_PERMISSION], [
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_PERMISSION], [
-	AC_MSG_CHECKING([whether iops->permission() takes struct user_namespace*])
-	ZFS_LINUX_TEST_RESULT([permission_userns], [
+	AC_MSG_CHECKING([whether iops->permission() takes struct mnt_idmap*])
+	ZFS_LINUX_TEST_RESULT([permission_mnt_idmap], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_IOPS_PERMISSION_USERNS, 1,
-		   [iops->permission() takes struct user_namespace*])
+		AC_DEFINE(HAVE_IOPS_PERMISSION_IDMAP, 1,
+		   [iops->permission() takes struct mnt_idmap*])
 	],[
-		AC_MSG_RESULT(no)
+		AC_MSG_CHECKING([whether iops->permission() takes struct user_namespace*])
+		ZFS_LINUX_TEST_RESULT([permission_userns], [
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_IOPS_PERMISSION_USERNS, 1,
+			   [iops->permission() takes struct user_namespace*])
+		],[
+			AC_MSG_RESULT(no)
+		])
 	])
 ])
diff --git a/config/kernel-inode-setattr.m4 b/config/kernel-inode-setattr.m4
new file mode 100644
index 00000000000..45755b4eb27
--- /dev/null
+++ b/config/kernel-inode-setattr.m4
@@ -0,0 +1,87 @@
+AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_SETATTR], [
+	dnl #
+	dnl # Linux 6.3 API
+	dnl # The first arg of setattr I/O operations handler type
+	dnl # is changed to struct mnt_idmap*
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_operations_setattr_mnt_idmap], [
+		#include <linux/fs.h>
+
+		int test_setattr(
+		    struct mnt_idmap *idmap,
+		    struct dentry *de, struct iattr *ia)
+		    { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.setattr = test_setattr,
+		};
+	],[])
+
+	dnl #
+	dnl # Linux 5.12 API
+	dnl # The setattr I/O operations handler type was extended to require
+	dnl # a struct user_namespace* as its first arg, to support idmapped
+	dnl # mounts.
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_operations_setattr_userns], [
+		#include <linux/fs.h>
+
+		int test_setattr(
+		    struct user_namespace *userns,
+		    struct dentry *de, struct iattr *ia)
+		    { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.setattr = test_setattr,
+		};
+	],[])
+
+	ZFS_LINUX_TEST_SRC([inode_operations_setattr], [
+		#include <linux/fs.h>
+
+		int test_setattr(
+		    struct dentry *de, struct iattr *ia)
+		    { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.setattr = test_setattr,
+		};
+	],[])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_INODE_SETATTR], [
+	dnl #
+	dnl # Kernel 6.3 test
+	dnl #
+	AC_MSG_CHECKING([whether iops->setattr() takes mnt_idmap])
+	ZFS_LINUX_TEST_RESULT([inode_operations_setattr_mnt_idmap], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_IDMAP_IOPS_SETATTR, 1,
+		    [iops->setattr() takes struct mnt_idmap*])
+	],[
+		AC_MSG_RESULT(no)
+		dnl #
+		dnl # Kernel 5.12 test
+		dnl #
+		AC_MSG_CHECKING([whether iops->setattr() takes user_namespace])
+		ZFS_LINUX_TEST_RESULT([inode_operations_setattr_userns], [
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_USERNS_IOPS_SETATTR, 1,
+			    [iops->setattr() takes struct user_namespace*])
+		],[
+			AC_MSG_RESULT(no)
+
+			AC_MSG_CHECKING([whether iops->setattr() exists])
+			ZFS_LINUX_TEST_RESULT([inode_operations_setattr], [
+				AC_MSG_RESULT(yes)
+				AC_DEFINE(HAVE_IOPS_SETATTR, 1,
+					[iops->setattr() exists])
+			],[
+				AC_MSG_RESULT(no)
+			])
+		])
+	])
+])
diff --git a/config/kernel-is_owner_or_cap.m4 b/config/kernel-is_owner_or_cap.m4
index a90cf3da641..4e9c002b77f 100644
--- a/config/kernel-is_owner_or_cap.m4
+++ b/config/kernel-is_owner_or_cap.m4
@@ -16,12 +16,20 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_OWNER_OR_CAPABLE], [
 		(void) inode_owner_or_capable(ip);
 	])
 
-	ZFS_LINUX_TEST_SRC([inode_owner_or_capable_idmapped], [
+	ZFS_LINUX_TEST_SRC([inode_owner_or_capable_userns], [
 		#include <linux/fs.h>
 	],[
 		struct inode *ip = NULL;
 		(void) inode_owner_or_capable(&init_user_ns, ip);
 	])
+
+	ZFS_LINUX_TEST_SRC([inode_owner_or_capable_mnt_idmap], [
+		#include <linux/fs.h>
+		#include <linux/mnt_idmapping.h>
+	],[
+		struct inode *ip = NULL;
+		(void) inode_owner_or_capable(&nop_mnt_idmap, ip);
+	])
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_INODE_OWNER_OR_CAPABLE], [
@@ -35,12 +43,21 @@ AC_DEFUN([ZFS_AC_KERNEL_INODE_OWNER_OR_CAPABLE], [
 
 		AC_MSG_CHECKING(
 		    [whether inode_owner_or_capable() takes user_ns])
-		ZFS_LINUX_TEST_RESULT([inode_owner_or_capable_idmapped], [
+		ZFS_LINUX_TEST_RESULT([inode_owner_or_capable_userns], [
 			AC_MSG_RESULT(yes)
-			AC_DEFINE(HAVE_INODE_OWNER_OR_CAPABLE_IDMAPPED, 1,
+			AC_DEFINE(HAVE_INODE_OWNER_OR_CAPABLE_USERNS, 1,
 			    [inode_owner_or_capable() takes user_ns])
 		],[
-			ZFS_LINUX_TEST_ERROR([capability])
+			AC_MSG_RESULT(no)
+			AC_MSG_CHECKING(
+			    [whether inode_owner_or_capable() takes mnt_idmap])
+			ZFS_LINUX_TEST_RESULT([inode_owner_or_capable_mnt_idmap], [
+				AC_MSG_RESULT(yes)
+				AC_DEFINE(HAVE_INODE_OWNER_OR_CAPABLE_IDMAP, 1,
+				    [inode_owner_or_capable() takes mnt_idmap])
+			], [
+				ZFS_LINUX_TEST_ERROR([capability])
+			])
 		])
 	])
 ])
diff --git a/config/kernel-mkdir.m4 b/config/kernel-mkdir.m4
index 6667ed04fa4..7407a791b84 100644
--- a/config/kernel-mkdir.m4
+++ b/config/kernel-mkdir.m4
@@ -2,6 +2,22 @@ dnl #
 dnl # Supported mkdir() interfaces checked newest to oldest.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_SRC_MKDIR], [
+	dnl #
+	dnl # 6.3 API change
+	dnl # mkdir() takes struct mnt_idmap * as the first arg
+	dnl #
+	ZFS_LINUX_TEST_SRC([mkdir_mnt_idmap], [
+		#include <linux/fs.h>
+
+		int mkdir(struct mnt_idmap *idmap,
+			struct inode *inode, struct dentry *dentry,
+			umode_t umode) { return 0; }
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.mkdir = mkdir,
+		};
+	],[])
+
 	dnl #
 	dnl # 5.12 API change
 	dnl # The struct user_namespace arg was added as the first argument to
@@ -43,25 +59,36 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_MKDIR], [
 
 AC_DEFUN([ZFS_AC_KERNEL_MKDIR], [
 	dnl #
-	dnl # 5.12 API change
-	dnl # The struct user_namespace arg was added as the first argument to
-	dnl # mkdir() of the iops structure.
+	dnl # 6.3 API change
+	dnl # mkdir() takes struct mnt_idmap * as the first arg
 	dnl #
-	AC_MSG_CHECKING([whether iops->mkdir() takes struct user_namespace*])
-	ZFS_LINUX_TEST_RESULT([mkdir_user_namespace], [
+	AC_MSG_CHECKING([whether iops->mkdir() takes struct mnt_idmap*])
+	ZFS_LINUX_TEST_RESULT([mkdir_mnt_idmap], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_IOPS_MKDIR_USERNS, 1,
-		    [iops->mkdir() takes struct user_namespace*])
+		AC_DEFINE(HAVE_IOPS_MKDIR_IDMAP, 1,
+		    [iops->mkdir() takes struct mnt_idmap*])
 	],[
-		AC_MSG_RESULT(no)
-
-		AC_MSG_CHECKING([whether iops->mkdir() takes umode_t])
-		ZFS_LINUX_TEST_RESULT([inode_operations_mkdir], [
+		dnl #
+		dnl # 5.12 API change
+		dnl # The struct user_namespace arg was added as the first argument to
+		dnl # mkdir() of the iops structure.
+		dnl #
+		AC_MSG_CHECKING([whether iops->mkdir() takes struct user_namespace*])
+		ZFS_LINUX_TEST_RESULT([mkdir_user_namespace], [
 			AC_MSG_RESULT(yes)
-			AC_DEFINE(HAVE_MKDIR_UMODE_T, 1,
-			    [iops->mkdir() takes umode_t])
+			AC_DEFINE(HAVE_IOPS_MKDIR_USERNS, 1,
+			    [iops->mkdir() takes struct user_namespace*])
 		],[
-			ZFS_LINUX_TEST_ERROR([mkdir()])
+			AC_MSG_RESULT(no)
+
+			AC_MSG_CHECKING([whether iops->mkdir() takes umode_t])
+			ZFS_LINUX_TEST_RESULT([inode_operations_mkdir], [
+				AC_MSG_RESULT(yes)
+				AC_DEFINE(HAVE_MKDIR_UMODE_T, 1,
+				    [iops->mkdir() takes umode_t])
+			],[
+				ZFS_LINUX_TEST_ERROR([mkdir()])
+			])
 		])
 	])
 ])
diff --git a/config/kernel-mknod.m4 b/config/kernel-mknod.m4
index ffe45106003..1494ec1ae4d 100644
--- a/config/kernel-mknod.m4
+++ b/config/kernel-mknod.m4
@@ -1,4 +1,22 @@
 AC_DEFUN([ZFS_AC_KERNEL_SRC_MKNOD], [
+	dnl #
+	dnl # 6.3 API change
+	dnl # The first arg is now struct mnt_idmap*
+	dnl #
+	ZFS_LINUX_TEST_SRC([mknod_mnt_idmap], [
+		#include <linux/fs.h>
+		#include <linux/sched.h>
+
+		int tmp_mknod(struct mnt_idmap *idmap,
+		    struct inode *inode ,struct dentry *dentry,
+		    umode_t u, dev_t d) { return 0; }
+
+		static const struct inode_operations
+			iops __attribute__ ((unused)) = {
+			.mknod          = tmp_mknod,
+		};
+	],[])
+
 	dnl #
 	dnl # 5.12 API change that added the struct user_namespace* arg
 	dnl # to the front of this function type's arg list.
@@ -19,12 +37,20 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_MKNOD], [
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_MKNOD], [
-	AC_MSG_CHECKING([whether iops->mknod() takes struct user_namespace*])
-	ZFS_LINUX_TEST_RESULT([mknod_userns], [
+	AC_MSG_CHECKING([whether iops->mknod() takes struct mnt_idmap*])
+	ZFS_LINUX_TEST_RESULT([mknod_mnt_idmap], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_IOPS_MKNOD_USERNS, 1,
-		    [iops->mknod() takes struct user_namespace*])
+		AC_DEFINE(HAVE_IOPS_MKNOD_IDMAP, 1,
+		    [iops->mknod() takes struct mnt_idmap*])
 	],[
 		AC_MSG_RESULT(no)
+		AC_MSG_CHECKING([whether iops->mknod() takes struct user_namespace*])
+		ZFS_LINUX_TEST_RESULT([mknod_userns], [
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_IOPS_MKNOD_USERNS, 1,
+			    [iops->mknod() takes struct user_namespace*])
+		],[
+			AC_MSG_RESULT(no)
+		])
 	])
 ])
diff --git a/config/kernel-rename.m4 b/config/kernel-rename.m4
index 302db43f574..06a9791bc8d 100644
--- a/config/kernel-rename.m4
+++ b/config/kernel-rename.m4
@@ -33,24 +33,63 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_RENAME], [
 			.rename = rename_fn,
 		};
 	],[])
+
+	dnl #
+	dnl # 6.3 API change - the first arg is now struct mnt_idmap*
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_operations_rename_mnt_idmap], [
+		#include <linux/fs.h>
+		int rename_fn(struct mnt_idmap *idmap, struct inode *sip,
+			struct dentry *sdp, struct inode *tip, struct dentry *tdp,
+			unsigned int flags) { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.rename = rename_fn,
+		};
+	],[])
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_RENAME], [
-	AC_MSG_CHECKING([whether iops->rename() takes struct user_namespace*])
-	ZFS_LINUX_TEST_RESULT([inode_operations_rename_userns], [
+	AC_MSG_CHECKING([whether iops->rename() takes struct mnt_idmap*])
+	ZFS_LINUX_TEST_RESULT([inode_operations_rename_mnt_idmap], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_IOPS_RENAME_USERNS, 1,
-		    [iops->rename() takes struct user_namespace*])
+		AC_DEFINE(HAVE_IOPS_RENAME_IDMAP, 1,
+		    [iops->rename() takes struct mnt_idmap*])
 	],[
-		AC_MSG_RESULT(no)
-
-		AC_MSG_CHECKING([whether iop->rename() wants flags])
-		ZFS_LINUX_TEST_RESULT([inode_operations_rename_flags], [
+		AC_MSG_CHECKING([whether iops->rename() takes struct user_namespace*])
+		ZFS_LINUX_TEST_RESULT([inode_operations_rename_userns], [
 			AC_MSG_RESULT(yes)
-			AC_DEFINE(HAVE_RENAME_WANTS_FLAGS, 1,
-				[iops->rename() wants flags])
+			AC_DEFINE(HAVE_IOPS_RENAME_USERNS, 1,
+			    [iops->rename() takes struct user_namespace*])
 		],[
 			AC_MSG_RESULT(no)
+
+			AC_MSG_CHECKING([whether iops->rename2() exists])
+			ZFS_LINUX_TEST_RESULT([inode_operations_rename2], [
+				AC_MSG_RESULT(yes)
+				AC_DEFINE(HAVE_RENAME2, 1, [iops->rename2() exists])
+			],[
+				AC_MSG_RESULT(no)
+
+				AC_MSG_CHECKING([whether iops->rename() wants flags])
+				ZFS_LINUX_TEST_RESULT([inode_operations_rename_flags], [
+					AC_MSG_RESULT(yes)
+					AC_DEFINE(HAVE_RENAME_WANTS_FLAGS, 1,
+						[iops->rename() wants flags])
+				],[
+					AC_MSG_RESULT(no)
+
+					AC_MSG_CHECKING([whether struct inode_operations_wrapper takes .rename2()])
+					ZFS_LINUX_TEST_RESULT([dir_inode_operations_wrapper_rename2], [
+						AC_MSG_RESULT(yes)
+						AC_DEFINE(HAVE_RENAME2_OPERATIONS_WRAPPER, 1,
+							[struct inode_operations_wrapper takes .rename2()])
+					],[
+						AC_MSG_RESULT(no)
+					])
+				])
+			])
 		])
 	])
 ])
diff --git a/config/kernel-setattr-prepare.m4 b/config/kernel-setattr-prepare.m4
index 24245aa5344..e02d6263e9c 100644
--- a/config/kernel-setattr-prepare.m4
+++ b/config/kernel-setattr-prepare.m4
@@ -27,26 +27,48 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_SETATTR_PREPARE], [
 		int error __attribute__ ((unused)) =
 			setattr_prepare(userns, dentry, attr);
 	])
+
+	dnl #
+	dnl # 6.3 API change
+	dnl # The first arg of setattr_prepare() is changed to struct mnt_idmap*
+	dnl #
+	ZFS_LINUX_TEST_SRC([setattr_prepare_mnt_idmap], [
+		#include <linux/fs.h>
+	], [
+		struct dentry *dentry = NULL;
+		struct iattr *attr = NULL;
+		struct mnt_idmap *idmap = NULL;
+		int error __attribute__ ((unused)) =
+			setattr_prepare(idmap, dentry, attr);
+	])
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_SETATTR_PREPARE], [
-	AC_MSG_CHECKING([whether setattr_prepare() is available and accepts struct user_namespace*])
-	ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare_userns],
+	AC_MSG_CHECKING([whether setattr_prepare() is available and accepts struct mnt_idmap*])
+	ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare_mnt_idmap],
 	    [setattr_prepare], [fs/attr.c], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_SETATTR_PREPARE_USERNS, 1,
-		    [setattr_prepare() accepts user_namespace])
+		AC_DEFINE(HAVE_SETATTR_PREPARE_IDMAP, 1,
+		    [setattr_prepare() accepts mnt_idmap])
 	], [
-		AC_MSG_RESULT(no)
-
-		AC_MSG_CHECKING([whether setattr_prepare() is available, doesn't accept user_namespace])
-		ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare],
-			[setattr_prepare], [fs/attr.c], [
+		AC_MSG_CHECKING([whether setattr_prepare() is available and accepts struct user_namespace*])
+		ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare_userns],
+		    [setattr_prepare], [fs/attr.c], [
 			AC_MSG_RESULT(yes)
-			AC_DEFINE(HAVE_SETATTR_PREPARE_NO_USERNS, 1,
-				[setattr_prepare() is available, doesn't accept user_namespace])
+			AC_DEFINE(HAVE_SETATTR_PREPARE_USERNS, 1,
+			    [setattr_prepare() accepts user_namespace])
 		], [
 			AC_MSG_RESULT(no)
+
+			AC_MSG_CHECKING([whether setattr_prepare() is available, doesn't accept user_namespace])
+			ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare],
+				[setattr_prepare], [fs/attr.c], [
+				AC_MSG_RESULT(yes)
+				AC_DEFINE(HAVE_SETATTR_PREPARE_NO_USERNS, 1,
+					[setattr_prepare() is available, doesn't accept user_namespace])
+			], [
+				AC_MSG_RESULT(no)
+			])
 		])
 	])
 ])
diff --git a/config/kernel-symlink.m4 b/config/kernel-symlink.m4
index d90366d04b7..a0333ed66a7 100644
--- a/config/kernel-symlink.m4
+++ b/config/kernel-symlink.m4
@@ -1,4 +1,20 @@
 AC_DEFUN([ZFS_AC_KERNEL_SRC_SYMLINK], [
+	dnl #
+	dnl # 6.3 API change that changed the first arg
+	dnl # to struct mnt_idmap*
+	dnl #
+	ZFS_LINUX_TEST_SRC([symlink_mnt_idmap], [
+		#include <linux/fs.h>
+		#include <linux/sched.h>
+		int tmp_symlink(struct mnt_idmap *idmap,
+		    struct inode *inode ,struct dentry *dentry,
+		    const char *path) { return 0; }
+
+		static const struct inode_operations
+			iops __attribute__ ((unused)) = {
+			.symlink                = tmp_symlink,
+		};
+	],[])
 	dnl #
 	dnl # 5.12 API change that added the struct user_namespace* arg
 	dnl # to the front of this function type's arg list.
@@ -19,12 +35,19 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_SYMLINK], [
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_SYMLINK], [
-	AC_MSG_CHECKING([whether iops->symlink() takes struct user_namespace*])
-	ZFS_LINUX_TEST_RESULT([symlink_userns], [
+	AC_MSG_CHECKING([whether iops->symlink() takes struct mnt_idmap*])
+	ZFS_LINUX_TEST_RESULT([symlink_mnt_idmap], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_IOPS_SYMLINK_USERNS, 1,
-		    [iops->symlink() takes struct user_namespace*])
+		AC_DEFINE(HAVE_IOPS_SYMLINK_IDMAP, 1,
+		    [iops->symlink() takes struct mnt_idmap*])
 	],[
-		AC_MSG_RESULT(no)
+		AC_MSG_CHECKING([whether iops->symlink() takes struct user_namespace*])
+		ZFS_LINUX_TEST_RESULT([symlink_userns], [
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_IOPS_SYMLINK_USERNS, 1,
+			    [iops->symlink() takes struct user_namespace*])
+		],[
+			AC_MSG_RESULT(no)
+		])
 	])
 ])
diff --git a/config/kernel-tmpfile.m4 b/config/kernel-tmpfile.m4
index 0e1deb3612f..cc18b8f65a8 100644
--- a/config/kernel-tmpfile.m4
+++ b/config/kernel-tmpfile.m4
@@ -4,6 +4,19 @@ dnl # Add support for i_op->tmpfile
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_SRC_TMPFILE], [
 	dnl #
+	dnl # 6.3 API change
+	dnl # The first arg is now struct mnt_idmap * 
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_operations_tmpfile_mnt_idmap], [
+		#include <linux/fs.h>
+		int tmpfile(struct mnt_idmap *idmap,
+		    struct inode *inode, struct file *file,
+		    umode_t mode) { return 0; }
+		static struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.tmpfile = tmpfile,
+		};
+	],[])
 	dnl # 6.1 API change
 	dnl # use struct file instead of struct dentry
 	dnl #
@@ -44,23 +57,29 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_TMPFILE], [
 
 AC_DEFUN([ZFS_AC_KERNEL_TMPFILE], [
 	AC_MSG_CHECKING([whether i_op->tmpfile() exists])
-	ZFS_LINUX_TEST_RESULT([inode_operations_tmpfile], [
+	ZFS_LINUX_TEST_RESULT([inode_operations_tmpfile_mnt_idmap], [
 		AC_MSG_RESULT(yes)
 		AC_DEFINE(HAVE_TMPFILE, 1, [i_op->tmpfile() exists])
-		AC_DEFINE(HAVE_TMPFILE_USERNS, 1, [i_op->tmpfile() has userns])
-	],[
-		ZFS_LINUX_TEST_RESULT([inode_operations_tmpfile_dentry_userns], [
+		AC_DEFINE(HAVE_TMPFILE_IDMAP, 1, [i_op->tmpfile() has mnt_idmap])
+	], [
+		ZFS_LINUX_TEST_RESULT([inode_operations_tmpfile], [
 			AC_MSG_RESULT(yes)
 			AC_DEFINE(HAVE_TMPFILE, 1, [i_op->tmpfile() exists])
 			AC_DEFINE(HAVE_TMPFILE_USERNS, 1, [i_op->tmpfile() has userns])
-			AC_DEFINE(HAVE_TMPFILE_DENTRY, 1, [i_op->tmpfile() uses old dentry signature])
 		],[
-			ZFS_LINUX_TEST_RESULT([inode_operations_tmpfile_dentry], [
+			ZFS_LINUX_TEST_RESULT([inode_operations_tmpfile_dentry_userns], [
 				AC_MSG_RESULT(yes)
 				AC_DEFINE(HAVE_TMPFILE, 1, [i_op->tmpfile() exists])
+				AC_DEFINE(HAVE_TMPFILE_USERNS, 1, [i_op->tmpfile() has userns])
 				AC_DEFINE(HAVE_TMPFILE_DENTRY, 1, [i_op->tmpfile() uses old dentry signature])
 			],[
-				ZFS_LINUX_REQUIRE_API([i_op->tmpfile()], [3.11])
+				ZFS_LINUX_TEST_RESULT([inode_operations_tmpfile_dentry], [
+					AC_MSG_RESULT(yes)
+					AC_DEFINE(HAVE_TMPFILE, 1, [i_op->tmpfile() exists])
+					AC_DEFINE(HAVE_TMPFILE_DENTRY, 1, [i_op->tmpfile() uses old dentry signature])
+				],[
+					ZFS_LINUX_REQUIRE_API([i_op->tmpfile()], [3.11])
+				])
 			])
 		])
 	])
diff --git a/config/kernel-xattr-handler.m4 b/config/kernel-xattr-handler.m4
index b6cbfa15500..6b8a08dbcc8 100644
--- a/config/kernel-xattr-handler.m4
+++ b/config/kernel-xattr-handler.m4
@@ -179,6 +179,21 @@ dnl #
 dnl # Supported xattr handler set() interfaces checked newest to oldest.
 dnl #
 AC_DEFUN([ZFS_AC_KERNEL_SRC_XATTR_HANDLER_SET], [
+	ZFS_LINUX_TEST_SRC([xattr_handler_set_mnt_idmap], [
+		#include <linux/xattr.h>
+
+		int set(const struct xattr_handler *handler,
+			struct mnt_idmap *idmap,
+			struct dentry *dentry, struct inode *inode,
+			const char *name, const void *buffer,
+			size_t size, int flags)
+			{ return 0; }
+		static const struct xattr_handler
+			xops __attribute__ ((unused)) = {
+			.set = set,
+		};
+	],[])
+
 	ZFS_LINUX_TEST_SRC([xattr_handler_set_userns], [
 		#include <linux/xattr.h>
 
@@ -240,53 +255,63 @@ AC_DEFUN([ZFS_AC_KERNEL_XATTR_HANDLER_SET], [
 	dnl # The xattr_handler->set() callback was changed to 8 arguments, and
 	dnl # struct user_namespace* was inserted as arg #2
 	dnl #
-	AC_MSG_CHECKING([whether xattr_handler->set() wants dentry, inode, and user_namespace])
-	ZFS_LINUX_TEST_RESULT([xattr_handler_set_userns], [
+	dnl # 6.3 API change,
+	dnl # The xattr_handler->set() callback 2nd arg is now struct mnt_idmap *
+	dnl #
+	AC_MSG_CHECKING([whether xattr_handler->set() wants dentry, inode, and mnt_idmap])
+	ZFS_LINUX_TEST_RESULT([xattr_handler_set_mnt_idmap], [
 		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_XATTR_SET_USERNS, 1,
-		    [xattr_handler->set() takes user_namespace])
-	],[
-		dnl #
-		dnl # 4.7 API change,
-		dnl # The xattr_handler->set() callback was changed to take both
-		dnl # dentry and inode.
-		dnl #
-		AC_MSG_RESULT(no)
-		AC_MSG_CHECKING([whether xattr_handler->set() wants dentry and inode])
-		ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry_inode], [
+		AC_DEFINE(HAVE_XATTR_SET_IDMAP, 1,
+		    [xattr_handler->set() takes mnt_idmap])
+	], [
+		AC_MSG_CHECKING([whether xattr_handler->set() wants dentry, inode, and user_namespace])
+		ZFS_LINUX_TEST_RESULT([xattr_handler_set_userns], [
 			AC_MSG_RESULT(yes)
-			AC_DEFINE(HAVE_XATTR_SET_DENTRY_INODE, 1,
-			    [xattr_handler->set() wants both dentry and inode])
+			AC_DEFINE(HAVE_XATTR_SET_USERNS, 1,
+			    [xattr_handler->set() takes user_namespace])
 		],[
 			dnl #
-			dnl # 4.4 API change,
-			dnl # The xattr_handler->set() callback was changed to take a
-			dnl # xattr_handler, and handler_flags argument was removed and
-			dnl # should be accessed by handler->flags.
+			dnl # 4.7 API change,
+			dnl # The xattr_handler->set() callback was changed to take both
+			dnl # dentry and inode.
 			dnl #
 			AC_MSG_RESULT(no)
-			AC_MSG_CHECKING(
-			    [whether xattr_handler->set() wants xattr_handler])
-			ZFS_LINUX_TEST_RESULT([xattr_handler_set_xattr_handler], [
+			AC_MSG_CHECKING([whether xattr_handler->set() wants dentry and inode])
+			ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry_inode], [
 				AC_MSG_RESULT(yes)
-				AC_DEFINE(HAVE_XATTR_SET_HANDLER, 1,
-				    [xattr_handler->set() wants xattr_handler])
+				AC_DEFINE(HAVE_XATTR_SET_DENTRY_INODE, 1,
+				    [xattr_handler->set() wants both dentry and inode])
 			],[
 				dnl #
-				dnl # 2.6.33 API change,
-				dnl # The xattr_handler->set() callback was changed
-				dnl # to take a dentry instead of an inode, and a
-				dnl # handler_flags argument was added.
+				dnl # 4.4 API change,
+				dnl # The xattr_handler->set() callback was changed to take a
+				dnl # xattr_handler, and handler_flags argument was removed and
+				dnl # should be accessed by handler->flags.
 				dnl #
 				AC_MSG_RESULT(no)
 				AC_MSG_CHECKING(
-				    [whether xattr_handler->set() wants dentry])
-				ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry], [
+				    [whether xattr_handler->set() wants xattr_handler])
+				ZFS_LINUX_TEST_RESULT([xattr_handler_set_xattr_handler], [
 					AC_MSG_RESULT(yes)
-					AC_DEFINE(HAVE_XATTR_SET_DENTRY, 1,
-					    [xattr_handler->set() wants dentry])
+					AC_DEFINE(HAVE_XATTR_SET_HANDLER, 1,
+					    [xattr_handler->set() wants xattr_handler])
 				],[
-					ZFS_LINUX_TEST_ERROR([xattr set()])
+					dnl #
+					dnl # 2.6.33 API change,
+					dnl # The xattr_handler->set() callback was changed
+					dnl # to take a dentry instead of an inode, and a
+					dnl # handler_flags argument was added.
+					dnl #
+					AC_MSG_RESULT(no)
+					AC_MSG_CHECKING(
+					    [whether xattr_handler->set() wants dentry])
+					ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry], [
+						AC_MSG_RESULT(yes)
+						AC_DEFINE(HAVE_XATTR_SET_DENTRY, 1,
+						    [xattr_handler->set() wants dentry])
+					],[
+						ZFS_LINUX_TEST_ERROR([xattr set()])
+					])
 				])
 			])
 		])
diff --git a/config/kernel.m4 b/config/kernel.m4
index 1998b831e96..b376a151694 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -69,6 +69,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_INODE_OWNER_OR_CAPABLE
 	ZFS_AC_KERNEL_SRC_XATTR
 	ZFS_AC_KERNEL_SRC_ACL
+	ZFS_AC_KERNEL_SRC_INODE_SETATTR
 	ZFS_AC_KERNEL_SRC_INODE_GETATTR
 	ZFS_AC_KERNEL_SRC_INODE_SET_FLAGS
 	ZFS_AC_KERNEL_SRC_INODE_SET_IVERSION
@@ -131,7 +132,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_KSTRTOUL
 	ZFS_AC_KERNEL_SRC_PERCPU
 	ZFS_AC_KERNEL_SRC_CPU_HOTPLUG
-	ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR_USERNS
+	ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR
 	ZFS_AC_KERNEL_SRC_MKNOD
 	ZFS_AC_KERNEL_SRC_SYMLINK
 	ZFS_AC_KERNEL_SRC_BIO_MAX_SEGS
@@ -189,6 +190,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_INODE_OWNER_OR_CAPABLE
 	ZFS_AC_KERNEL_XATTR
 	ZFS_AC_KERNEL_ACL
+	ZFS_AC_KERNEL_INODE_SETATTR
 	ZFS_AC_KERNEL_INODE_GETATTR
 	ZFS_AC_KERNEL_INODE_SET_FLAGS
 	ZFS_AC_KERNEL_INODE_SET_IVERSION
@@ -251,7 +253,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_KSTRTOUL
 	ZFS_AC_KERNEL_PERCPU
 	ZFS_AC_KERNEL_CPU_HOTPLUG
-	ZFS_AC_KERNEL_GENERIC_FILLATTR_USERNS
+	ZFS_AC_KERNEL_GENERIC_FILLATTR
 	ZFS_AC_KERNEL_MKNOD
 	ZFS_AC_KERNEL_SYMLINK
 	ZFS_AC_KERNEL_BIO_MAX_SEGS
diff --git a/include/os/freebsd/spl/sys/types.h b/include/os/freebsd/spl/sys/types.h
index 6557c840feb..bbb81f9f840 100644
--- a/include/os/freebsd/spl/sys/types.h
+++ b/include/os/freebsd/spl/sys/types.h
@@ -104,7 +104,7 @@ typedef	u_longlong_t	len_t;
 
 typedef	longlong_t	diskaddr_t;
 
-typedef void		zuserns_t;
+typedef void		zidmap_t;
 
 #include <sys/debug.h>
 #endif	/* !_OPENSOLARIS_SYS_TYPES_H_ */
diff --git a/include/os/freebsd/zfs/sys/zfs_vnops_os.h b/include/os/freebsd/zfs/sys/zfs_vnops_os.h
index 460aecd2e70..b79cccfcf35 100644
--- a/include/os/freebsd/zfs/sys/zfs_vnops_os.h
+++ b/include/os/freebsd/zfs/sys/zfs_vnops_os.h
@@ -35,22 +35,22 @@ int dmu_read_pages(objset_t *os, uint64_t object, vm_page_t *ma, int count,
     int *rbehind, int *rahead, int last_size);
 extern int zfs_remove(znode_t *dzp, const char *name, cred_t *cr, int flags);
 extern int zfs_mkdir(znode_t *dzp, const char *dirname, vattr_t *vap,
-    znode_t **zpp, cred_t *cr, int flags, vsecattr_t *vsecp, zuserns_t *mnt_ns);
+    znode_t **zpp, cred_t *cr, int flags, vsecattr_t *vsecp, zidmap_t *mnt_ns);
 extern int zfs_rmdir(znode_t *dzp, const char *name, znode_t *cwd,
     cred_t *cr, int flags);
 extern int zfs_setattr(znode_t *zp, vattr_t *vap, int flag, cred_t *cr,
-    zuserns_t *mnt_ns);
+    zidmap_t *mnt_ns);
 extern int zfs_rename(znode_t *sdzp, const char *snm, znode_t *tdzp,
-    const char *tnm, cred_t *cr, int flags, zuserns_t *mnt_ns);
+    const char *tnm, cred_t *cr, int flags, zidmap_t *mnt_ns);
 extern int zfs_symlink(znode_t *dzp, const char *name, vattr_t *vap,
-    const char *link, znode_t **zpp, cred_t *cr, int flags, zuserns_t *mnt_ns);
+    const char *link, znode_t **zpp, cred_t *cr, int flags, zidmap_t *mnt_ns);
 extern int zfs_link(znode_t *tdzp, znode_t *sp,
     const char *name, cred_t *cr, int flags);
 extern int zfs_space(znode_t *zp, int cmd, struct flock *bfp, int flag,
     offset_t offset, cred_t *cr);
 extern int zfs_create(znode_t *dzp, const char *name, vattr_t *vap, int excl,
     int mode, znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp,
-    zuserns_t *mnt_ns);
+    zidmap_t *mnt_ns);
 extern int zfs_setsecattr(znode_t *zp, vsecattr_t *vsecp, int flag,
     cred_t *cr);
 extern int zfs_write_simple(znode_t *zp, const void *data, size_t len,
diff --git a/include/os/linux/kernel/linux/vfs_compat.h b/include/os/linux/kernel/linux/vfs_compat.h
index 91e908598fb..e82bbf755d5 100644
--- a/include/os/linux/kernel/linux/vfs_compat.h
+++ b/include/os/linux/kernel/linux/vfs_compat.h
@@ -344,7 +344,8 @@ static inline void zfs_gid_write(struct inode *ip, gid_t gid)
  * 4.9 API change
  */
 #if !(defined(HAVE_SETATTR_PREPARE_NO_USERNS) || \
-    defined(HAVE_SETATTR_PREPARE_USERNS))
+    defined(HAVE_SETATTR_PREPARE_USERNS) || \
+    defined(HAVE_SETATTR_PREPARE_IDMAP))
 static inline int
 setattr_prepare(struct dentry *dentry, struct iattr *ia)
 {
@@ -399,6 +400,15 @@ func(struct user_namespace *user_ns, const struct path *path,	\
 	return (func##_impl(user_ns, path, stat, request_mask, \
 	    query_flags));	\
 }
+#elif defined(HAVE_IDMAP_IOPS_GETATTR)
+#define	ZPL_GETATTR_WRAPPER(func)					\
+static int								\
+func(struct mnt_idmap *user_ns, const struct path *path,	\
+    struct kstat *stat, u32 request_mask, unsigned int query_flags)	\
+{									\
+	return (func##_impl(user_ns, path, stat, request_mask,	\
+	    query_flags));	\
+}
 #else
 #error
 #endif
@@ -450,8 +460,15 @@ zpl_is_32bit_api(void)
  * 5.12 API change
  * To support id-mapped mounts, generic_fillattr() was modified to
  * accept a new struct user_namespace* as its first arg.
+ *
+ * 6.3 API change
+ * generic_fillattr() first arg is changed to struct mnt_idmap *
+ *
  */
-#ifdef HAVE_GENERIC_FILLATTR_USERNS
+#ifdef HAVE_GENERIC_FILLATTR_IDMAP
+#define	zpl_generic_fillattr(idmap, ip, sp)	\
+    generic_fillattr(idmap, ip, sp)
+#elif defined(HAVE_GENERIC_FILLATTR_USERNS)
 #define	zpl_generic_fillattr(user_ns, ip, sp)	\
     generic_fillattr(user_ns, ip, sp)
 #else
diff --git a/include/os/linux/kernel/linux/xattr_compat.h b/include/os/linux/kernel/linux/xattr_compat.h
index 83763c64a14..700454c26de 100644
--- a/include/os/linux/kernel/linux/xattr_compat.h
+++ b/include/os/linux/kernel/linux/xattr_compat.h
@@ -133,13 +133,28 @@ fn(const struct xattr_handler *handler, struct dentry *dentry,		\
 #error "Unsupported kernel"
 #endif
 
+/*
+ * 6.3 API change,
+ * The xattr_handler->set() callback was changed to take the
+ * struct mnt_idmap* as the first arg, to support idmapped
+ * mounts.
+ */
+#if defined(HAVE_XATTR_SET_IDMAP)
+#define	ZPL_XATTR_SET_WRAPPER(fn)					\
+static int								\
+fn(const struct xattr_handler *handler, struct mnt_idmap *user_ns,	\
+    struct dentry *dentry, struct inode *inode, const char *name,	\
+    const void *buffer, size_t size, int flags)	\
+{									\
+	return (__ ## fn(user_ns, inode, name, buffer, size, flags));	\
+}
 /*
  * 5.12 API change,
  * The xattr_handler->set() callback was changed to take the
  * struct user_namespace* as the first arg, to support idmapped
  * mounts.
  */
-#if defined(HAVE_XATTR_SET_USERNS)
+#elif defined(HAVE_XATTR_SET_USERNS)
 #define	ZPL_XATTR_SET_WRAPPER(fn)					\
 static int								\
 fn(const struct xattr_handler *handler, struct user_namespace *user_ns, \
diff --git a/include/os/linux/spl/sys/cred.h b/include/os/linux/spl/sys/cred.h
index 75ad400d312..7fd5f644863 100644
--- a/include/os/linux/spl/sys/cred.h
+++ b/include/os/linux/spl/sys/cred.h
@@ -48,6 +48,8 @@ extern struct task_struct init_task;
 #define	SGID_TO_KGID(x)		(KGIDT_INIT(x))
 #define	KGIDP_TO_SGIDP(x)	(&(x)->val)
 
+extern zidmap_t *zfs_get_init_idmap(void);
+
 /* Check if the user ns is the initial one */
 static inline boolean_t
 zfs_is_init_userns(struct user_namespace *user_ns)
@@ -74,36 +76,39 @@ static inline boolean_t zfs_no_idmapping(struct user_namespace *mnt_userns,
 	return (zfs_is_init_userns(mnt_userns) || mnt_userns == fs_userns);
 }
 
-static inline uid_t zfs_uid_to_vfsuid(struct user_namespace *mnt_userns,
+static inline uid_t zfs_uid_to_vfsuid(zidmap_t *mnt_userns,
     struct user_namespace *fs_userns, uid_t uid)
 {
-	if (zfs_no_idmapping(mnt_userns, fs_userns))
+	struct user_namespace *owner = idmap_owner(mnt_userns);
+	if (zfs_no_idmapping(owner, fs_userns))
 		return (uid);
 	if (!zfs_is_init_userns(fs_userns))
 		uid = from_kuid(fs_userns, KUIDT_INIT(uid));
 	if (uid == (uid_t)-1)
 		return (uid);
-	return (__kuid_val(make_kuid(mnt_userns, uid)));
+	return (__kuid_val(make_kuid(owner, uid)));
 }
 
-static inline gid_t zfs_gid_to_vfsgid(struct user_namespace *mnt_userns,
+static inline gid_t zfs_gid_to_vfsgid(zidmap_t *mnt_userns,
     struct user_namespace *fs_userns, gid_t gid)
 {
-	if (zfs_no_idmapping(mnt_userns, fs_userns))
+	struct user_namespace *owner = idmap_owner(mnt_userns);
+	if (zfs_no_idmapping(owner, fs_userns))
 		return (gid);
 	if (!zfs_is_init_userns(fs_userns))
 		gid = from_kgid(fs_userns, KGIDT_INIT(gid));
 	if (gid == (gid_t)-1)
 		return (gid);
-	return (__kgid_val(make_kgid(mnt_userns, gid)));
+	return (__kgid_val(make_kgid(owner, gid)));
 }
 
-static inline uid_t zfs_vfsuid_to_uid(struct user_namespace *mnt_userns,
+static inline uid_t zfs_vfsuid_to_uid(zidmap_t *mnt_userns,
     struct user_namespace *fs_userns, uid_t uid)
 {
-	if (zfs_no_idmapping(mnt_userns, fs_userns))
+	struct user_namespace *owner = idmap_owner(mnt_userns);
+	if (zfs_no_idmapping(owner, fs_userns))
 		return (uid);
-	uid = from_kuid(mnt_userns, KUIDT_INIT(uid));
+	uid = from_kuid(owner, KUIDT_INIT(uid));
 	if (uid == (uid_t)-1)
 		return (uid);
 	if (zfs_is_init_userns(fs_userns))
@@ -111,12 +116,13 @@ static inline uid_t zfs_vfsuid_to_uid(struct user_namespace *mnt_userns,
 	return (__kuid_val(make_kuid(fs_userns, uid)));
 }
 
-static inline gid_t zfs_vfsgid_to_gid(struct user_namespace *mnt_userns,
+static inline gid_t zfs_vfsgid_to_gid(zidmap_t *mnt_userns,
     struct user_namespace *fs_userns, gid_t gid)
 {
-	if (zfs_no_idmapping(mnt_userns, fs_userns))
+	struct user_namespace *owner = idmap_owner(mnt_userns);
+	if (zfs_no_idmapping(owner, fs_userns))
 		return (gid);
-	gid = from_kgid(mnt_userns, KGIDT_INIT(gid));
+	gid = from_kgid(owner, KGIDT_INIT(gid));
 	if (gid == (gid_t)-1)
 		return (gid);
 	if (zfs_is_init_userns(fs_userns))
diff --git a/include/os/linux/spl/sys/types.h b/include/os/linux/spl/sys/types.h
index cae1bbddf10..a7666187ec2 100644
--- a/include/os/linux/spl/sys/types.h
+++ b/include/os/linux/spl/sys/types.h
@@ -55,6 +55,19 @@ typedef int			major_t;
 typedef int			minor_t;
 
 struct user_namespace;
-typedef struct user_namespace	zuserns_t;
+#ifdef HAVE_IOPS_CREATE_IDMAP
+#include <linux/refcount.h>
+struct mnt_idmap {
+	struct user_namespace *owner;
+	refcount_t count;
+};
+typedef struct mnt_idmap	zidmap_t;
+#define	idmap_owner(p)	(((struct mnt_idmap *)p)->owner)
+#else
+typedef struct user_namespace	zidmap_t;
+#define	idmap_owner(p)	((struct user_namespace *)p)
+#endif
+
+extern zidmap_t *zfs_init_idmap;
 
 #endif	/* _SPL_TYPES_H */
diff --git a/include/os/linux/zfs/sys/policy.h b/include/os/linux/zfs/sys/policy.h
index 7548804b9ee..ab352fd30cb 100644
--- a/include/os/linux/zfs/sys/policy.h
+++ b/include/os/linux/zfs/sys/policy.h
@@ -47,14 +47,14 @@ int secpolicy_vnode_create_gid(const cred_t *);
 int secpolicy_vnode_remove(const cred_t *);
 int secpolicy_vnode_setdac(const cred_t *, uid_t);
 int secpolicy_vnode_setid_retain(struct znode *, const cred_t *, boolean_t);
-int secpolicy_vnode_setids_setgids(const cred_t *, gid_t, zuserns_t *,
-    zuserns_t *);
+int secpolicy_vnode_setids_setgids(const cred_t *, gid_t, zidmap_t *,
+    struct user_namespace *);
 int secpolicy_zinject(const cred_t *);
 int secpolicy_zfs(const cred_t *);
 int secpolicy_zfs_proc(const cred_t *, proc_t *);
 void secpolicy_setid_clear(vattr_t *, cred_t *);
 int secpolicy_setid_setsticky_clear(struct inode *, vattr_t *,
-    const vattr_t *, cred_t *, zuserns_t *, zuserns_t *);
+    const vattr_t *, cred_t *, zidmap_t *, struct user_namespace *);
 int secpolicy_xvattr(xvattr_t *, uid_t, cred_t *, mode_t);
 int secpolicy_vnode_setattr(cred_t *, struct inode *, struct vattr *,
     const struct vattr *, int, int (void *, int, cred_t *), void *);
diff --git a/include/os/linux/zfs/sys/zfs_vnops_os.h b/include/os/linux/zfs/sys/zfs_vnops_os.h
index fcb32308562..941eb93e97f 100644
--- a/include/os/linux/zfs/sys/zfs_vnops_os.h
+++ b/include/os/linux/zfs/sys/zfs_vnops_os.h
@@ -46,24 +46,23 @@ extern int zfs_lookup(znode_t *dzp, char *nm, znode_t **zpp, int flags,
     cred_t *cr, int *direntflags, pathname_t *realpnp);
 extern int zfs_create(znode_t *dzp, char *name, vattr_t *vap, int excl,
     int mode, znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp,
-    zuserns_t *mnt_ns);
+    zidmap_t *mnt_ns);
 extern int zfs_tmpfile(struct inode *dip, vattr_t *vapzfs, int excl,
     int mode, struct inode **ipp, cred_t *cr, int flag, vsecattr_t *vsecp,
-    zuserns_t *mnt_ns);
+    zidmap_t *mnt_ns);
 extern int zfs_remove(znode_t *dzp, char *name, cred_t *cr, int flags);
 extern int zfs_mkdir(znode_t *dzp, char *dirname, vattr_t *vap,
-    znode_t **zpp, cred_t *cr, int flags, vsecattr_t *vsecp, zuserns_t *mnt_ns);
+    znode_t **zpp, cred_t *cr, int flags, vsecattr_t *vsecp, zidmap_t *mnt_ns);
 extern int zfs_rmdir(znode_t *dzp, char *name, znode_t *cwd,
     cred_t *cr, int flags);
 extern int zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr);
-extern int zfs_getattr_fast(struct user_namespace *, struct inode *ip,
-	struct kstat *sp);
+extern int zfs_getattr_fast(zidmap_t *, struct inode *ip, struct kstat *sp);
 extern int zfs_setattr(znode_t *zp, vattr_t *vap, int flag, cred_t *cr,
-    zuserns_t *mnt_ns);
+    zidmap_t *mnt_ns);
 extern int zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp,
-    char *tnm, cred_t *cr, int flags, zuserns_t *mnt_ns);
+    char *tnm, cred_t *cr, int flags, zidmap_t *mnt_ns);
 extern int zfs_symlink(znode_t *dzp, char *name, vattr_t *vap,
-    char *link, znode_t **zpp, cred_t *cr, int flags, zuserns_t *mnt_ns);
+    char *link, znode_t **zpp, cred_t *cr, int flags, zidmap_t *mnt_ns);
 extern int zfs_readlink(struct inode *ip, zfs_uio_t *uio, cred_t *cr);
 extern int zfs_link(znode_t *tdzp, znode_t *szp,
     char *name, cred_t *cr, int flags);
diff --git a/include/os/linux/zfs/sys/zpl.h b/include/os/linux/zfs/sys/zpl.h
index 703e335c28a..795b9b4f4ce 100644
--- a/include/os/linux/zfs/sys/zpl.h
+++ b/include/os/linux/zfs/sys/zpl.h
@@ -39,7 +39,7 @@
 
 /* zpl_inode.c */
 extern void zpl_vap_init(vattr_t *vap, struct inode *dir,
-    umode_t mode, cred_t *cr, zuserns_t *mnt_ns);
+    umode_t mode, cred_t *cr, zidmap_t *mnt_ns);
 
 extern const struct inode_operations zpl_inode_operations;
 extern const struct inode_operations zpl_dir_inode_operations;
@@ -64,7 +64,10 @@ extern int zpl_xattr_security_init(struct inode *ip, struct inode *dip,
     const struct qstr *qstr);
 #if defined(CONFIG_FS_POSIX_ACL)
 #if defined(HAVE_SET_ACL)
-#if defined(HAVE_SET_ACL_USERNS)
+#if defined(HAVE_SET_ACL_IDMAP_DENTRY)
+extern int zpl_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
+    struct posix_acl *acl, int type);
+#elif defined(HAVE_SET_ACL_USERNS)
 extern int zpl_set_acl(struct user_namespace *userns, struct inode *ip,
     struct posix_acl *acl, int type);
 #elif defined(HAVE_SET_ACL_USERNS_DENTRY_ARG2)
@@ -186,13 +189,15 @@ zpl_dir_emit_dots(struct file *file, zpl_dir_context_t *ctx)
 
 #if defined(HAVE_INODE_OWNER_OR_CAPABLE)
 #define	zpl_inode_owner_or_capable(ns, ip)	inode_owner_or_capable(ip)
-#elif defined(HAVE_INODE_OWNER_OR_CAPABLE_IDMAPPED)
+#elif defined(HAVE_INODE_OWNER_OR_CAPABLE_USERNS)
 #define	zpl_inode_owner_or_capable(ns, ip)	inode_owner_or_capable(ns, ip)
+#elif defined(HAVE_INODE_OWNER_OR_CAPABLE_IDMAP)
+#define	zpl_inode_owner_or_capable(idmap, ip) inode_owner_or_capable(idmap, ip)
 #else
 #error "Unsupported kernel"
 #endif
 
-#ifdef HAVE_SETATTR_PREPARE_USERNS
+#if defined(HAVE_SETATTR_PREPARE_USERNS) || defined(HAVE_SETATTR_PREPARE_IDMAP)
 #define	zpl_setattr_prepare(ns, dentry, ia)	setattr_prepare(ns, dentry, ia)
 #else
 /*
diff --git a/include/sys/zfs_acl.h b/include/sys/zfs_acl.h
index 93a1f7f6172..55af29cc000 100644
--- a/include/sys/zfs_acl.h
+++ b/include/sys/zfs_acl.h
@@ -206,7 +206,7 @@ struct zfsvfs;
 
 #ifdef _KERNEL
 int zfs_acl_ids_create(struct znode *, int, vattr_t *,
-    cred_t *, vsecattr_t *, zfs_acl_ids_t *, zuserns_t *);
+    cred_t *, vsecattr_t *, zfs_acl_ids_t *, zidmap_t *);
 void zfs_acl_ids_free(zfs_acl_ids_t *);
 boolean_t zfs_acl_ids_overquota(struct zfsvfs *, zfs_acl_ids_t *, uint64_t);
 int zfs_getacl(struct znode *, vsecattr_t *, boolean_t, cred_t *);
@@ -216,15 +216,15 @@ void zfs_oldace_byteswap(ace_t *, int);
 void zfs_ace_byteswap(void *, size_t, boolean_t);
 extern boolean_t zfs_has_access(struct znode *zp, cred_t *cr);
 extern int zfs_zaccess(struct znode *, int, int, boolean_t, cred_t *,
-    zuserns_t *);
+    zidmap_t *);
 int zfs_fastaccesschk_execute(struct znode *, cred_t *);
-extern int zfs_zaccess_rwx(struct znode *, mode_t, int, cred_t *, zuserns_t *);
-extern int zfs_zaccess_unix(struct znode *, mode_t, cred_t *);
+extern int zfs_zaccess_rwx(struct znode *, mode_t, int, cred_t *, zidmap_t *);
+extern int zfs_zaccess_unix(void *, int, cred_t *);
 extern int zfs_acl_access(struct znode *, int, cred_t *);
 int zfs_acl_chmod_setattr(struct znode *, zfs_acl_t **, uint64_t);
-int zfs_zaccess_delete(struct znode *, struct znode *, cred_t *, zuserns_t *);
+int zfs_zaccess_delete(struct znode *, struct znode *, cred_t *, zidmap_t *);
 int zfs_zaccess_rename(struct znode *, struct znode *,
-    struct znode *, struct znode *, cred_t *cr, zuserns_t *mnt_ns);
+    struct znode *, struct znode *, cred_t *cr, zidmap_t *mnt_ns);
 void zfs_acl_free(zfs_acl_t *);
 int zfs_vsec_2_aclp(struct zfsvfs *, umode_t, vsecattr_t *, cred_t *,
     struct zfs_fuid_info **, zfs_acl_t **);
diff --git a/module/os/freebsd/zfs/zfs_acl.c b/module/os/freebsd/zfs/zfs_acl.c
index ca50f442a07..060bf143136 100644
--- a/module/os/freebsd/zfs/zfs_acl.c
+++ b/module/os/freebsd/zfs/zfs_acl.c
@@ -1618,7 +1618,7 @@ zfs_acl_inherit(zfsvfs_t *zfsvfs, vtype_t vtype, zfs_acl_t *paclp,
  */
 int
 zfs_acl_ids_create(znode_t *dzp, int flag, vattr_t *vap, cred_t *cr,
-    vsecattr_t *vsecp, zfs_acl_ids_t *acl_ids, zuserns_t *mnt_ns)
+    vsecattr_t *vsecp, zfs_acl_ids_t *acl_ids, zidmap_t *mnt_ns)
 {
 	int		error;
 	zfsvfs_t	*zfsvfs = dzp->z_zfsvfs;
@@ -2341,7 +2341,7 @@ zfs_fastaccesschk_execute(znode_t *zdp, cred_t *cr)
  */
 int
 zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr,
-    zuserns_t *mnt_ns)
+    zidmap_t *mnt_ns)
 {
 	uint32_t	working_mode;
 	int		error;
@@ -2472,7 +2472,7 @@ zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr,
  */
 int
 zfs_zaccess_rwx(znode_t *zp, mode_t mode, int flags, cred_t *cr,
-    zuserns_t *mnt_ns)
+    zidmap_t *mnt_ns)
 {
 	return (zfs_zaccess(zp, zfs_unix_to_v4(mode >> 6), flags, B_FALSE, cr,
 	    mnt_ns));
@@ -2542,7 +2542,7 @@ zfs_delete_final_check(znode_t *zp, znode_t *dzp,
  *
  */
 int
-zfs_zaccess_delete(znode_t *dzp, znode_t *zp, cred_t *cr, zuserns_t *mnt_ns)
+zfs_zaccess_delete(znode_t *dzp, znode_t *zp, cred_t *cr, zidmap_t *mnt_ns)
 {
 	uint32_t dzp_working_mode = 0;
 	uint32_t zp_working_mode = 0;
@@ -2629,7 +2629,7 @@ zfs_zaccess_delete(znode_t *dzp, znode_t *zp, cred_t *cr, zuserns_t *mnt_ns)
 
 int
 zfs_zaccess_rename(znode_t *sdzp, znode_t *szp, znode_t *tdzp,
-    znode_t *tzp, cred_t *cr, zuserns_t *mnt_ns)
+    znode_t *tzp, cred_t *cr, zidmap_t *mnt_ns)
 {
 	int add_perm;
 	int error;
diff --git a/module/os/freebsd/zfs/zfs_vnops_os.c b/module/os/freebsd/zfs/zfs_vnops_os.c
index 0b7bbbdc52b..145ad4680b2 100644
--- a/module/os/freebsd/zfs/zfs_vnops_os.c
+++ b/module/os/freebsd/zfs/zfs_vnops_os.c
@@ -1062,7 +1062,7 @@ zfs_lookup(vnode_t *dvp, const char *nm, vnode_t **vpp,
 /* ARGSUSED */
 int
 zfs_create(znode_t *dzp, const char *name, vattr_t *vap, int excl, int mode,
-    znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp, zuserns_t *mnt_ns)
+    znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp, zidmap_t *mnt_ns)
 {
 	znode_t		*zp;
 	zfsvfs_t	*zfsvfs = dzp->z_zfsvfs;
@@ -1413,7 +1413,7 @@ zfs_remove(znode_t *dzp, const char *name, cred_t *cr, int flags)
 /*ARGSUSED*/
 int
 zfs_mkdir(znode_t *dzp, const char *dirname, vattr_t *vap, znode_t **zpp,
-    cred_t *cr, int flags, vsecattr_t *vsecp, zuserns_t *mnt_ns)
+    cred_t *cr, int flags, vsecattr_t *vsecp, zidmap_t *mnt_ns)
 {
 	znode_t		*zp;
 	zfsvfs_t	*zfsvfs = dzp->z_zfsvfs;
@@ -2224,7 +2224,7 @@ zfs_getattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr)
  */
 /* ARGSUSED */
 int
-zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr, zuserns_t *mnt_ns)
+zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr, zidmap_t *mnt_ns)
 {
 	vnode_t		*vp = ZTOV(zp);
 	zfsvfs_t	*zfsvfs = zp->z_zfsvfs;
@@ -3478,7 +3478,7 @@ zfs_do_rename_impl(vnode_t *sdvp, vnode_t **svpp, struct componentname *scnp,
 
 int
 zfs_rename(znode_t *sdzp, const char *sname, znode_t *tdzp, const char *tname,
-    cred_t *cr, int flags, zuserns_t *mnt_ns)
+    cred_t *cr, int flags, zidmap_t *mnt_ns)
 {
 	struct componentname scn, tcn;
 	vnode_t *sdvp, *tdvp;
@@ -3533,7 +3533,7 @@ zfs_rename(znode_t *sdzp, const char *sname, znode_t *tdzp, const char *tname,
 /*ARGSUSED*/
 int
 zfs_symlink(znode_t *dzp, const char *name, vattr_t *vap,
-    const char *link, znode_t **zpp, cred_t *cr, int flags, zuserns_t *mnt_ns)
+    const char *link, znode_t **zpp, cred_t *cr, int flags, zidmap_t *mnt_ns)
 {
 	znode_t		*zp;
 	dmu_tx_t	*tx;
diff --git a/module/os/linux/spl/spl-cred.c b/module/os/linux/spl/spl-cred.c
index f81b9540a63..d407fc66b2d 100644
--- a/module/os/linux/spl/spl-cred.c
+++ b/module/os/linux/spl/spl-cred.c
@@ -145,6 +145,18 @@ crgetgid(const cred_t *cr)
 	return (KGID_TO_SGID(cr->fsgid));
 }
 
+/* Return the initial user ns or nop_mnt_idmap */
+zidmap_t *
+zfs_get_init_idmap(void)
+{
+#ifdef HAVE_IOPS_CREATE_IDMAP
+	return ((zidmap_t *)&nop_mnt_idmap);
+#else
+	return ((zidmap_t *)&init_user_ns);
+#endif
+}
+
+EXPORT_SYMBOL(zfs_get_init_idmap);
 EXPORT_SYMBOL(crhold);
 EXPORT_SYMBOL(crfree);
 EXPORT_SYMBOL(crgetuid);
diff --git a/module/os/linux/zfs/policy.c b/module/os/linux/zfs/policy.c
index e879ec32c20..cc831bbb339 100644
--- a/module/os/linux/zfs/policy.c
+++ b/module/os/linux/zfs/policy.c
@@ -124,7 +124,7 @@ secpolicy_vnode_any_access(const cred_t *cr, struct inode *ip, uid_t owner)
 	if (crgetuid(cr) == owner)
 		return (0);
 
-	if (zpl_inode_owner_or_capable(kcred->user_ns, ip))
+	if (zpl_inode_owner_or_capable(zfs_init_idmap, ip))
 		return (0);
 
 #if defined(CONFIG_USER_NS)
@@ -214,8 +214,8 @@ secpolicy_vnode_setid_retain(struct znode *zp __maybe_unused, const cred_t *cr,
  * Determine that subject can set the file setgid flag.
  */
 int
-secpolicy_vnode_setids_setgids(const cred_t *cr, gid_t gid, zuserns_t *mnt_ns,
-    zuserns_t *fs_ns)
+secpolicy_vnode_setids_setgids(const cred_t *cr, gid_t gid, zidmap_t *mnt_ns,
+    struct user_namespace *fs_ns)
 {
 	gid = zfs_gid_to_vfsgid(mnt_ns, fs_ns, gid);
 #if defined(CONFIG_USER_NS)
@@ -286,8 +286,8 @@ secpolicy_setid_clear(vattr_t *vap, cred_t *cr)
  * Determine that subject can set the file setid flags.
  */
 static int
-secpolicy_vnode_setid_modify(const cred_t *cr, uid_t owner, zuserns_t *mnt_ns,
-    zuserns_t *fs_ns)
+secpolicy_vnode_setid_modify(const cred_t *cr, uid_t owner, zidmap_t *mnt_ns,
+    struct user_namespace *fs_ns)
 {
 	owner = zfs_uid_to_vfsuid(mnt_ns, fs_ns, owner);
 
@@ -315,7 +315,8 @@ secpolicy_vnode_stky_modify(const cred_t *cr)
 
 int
 secpolicy_setid_setsticky_clear(struct inode *ip, vattr_t *vap,
-    const vattr_t *ovap, cred_t *cr, zuserns_t *mnt_ns, zuserns_t *fs_ns)
+    const vattr_t *ovap, cred_t *cr, zidmap_t *mnt_ns,
+    struct user_namespace *fs_ns)
 {
 	int error;
 
diff --git a/module/os/linux/zfs/zfs_acl.c b/module/os/linux/zfs/zfs_acl.c
index 3d31da6e35b..7014ccd22a3 100644
--- a/module/os/linux/zfs/zfs_acl.c
+++ b/module/os/linux/zfs/zfs_acl.c
@@ -1801,7 +1801,7 @@ zfs_acl_inherit(zfsvfs_t *zfsvfs, umode_t va_mode, zfs_acl_t *paclp,
  */
 int
 zfs_acl_ids_create(znode_t *dzp, int flag, vattr_t *vap, cred_t *cr,
-    vsecattr_t *vsecp, zfs_acl_ids_t *acl_ids, zuserns_t *mnt_ns)
+    vsecattr_t *vsecp, zfs_acl_ids_t *acl_ids, zidmap_t *mnt_ns)
 {
 	int		error;
 	zfsvfs_t	*zfsvfs = ZTOZSB(dzp);
@@ -1980,7 +1980,7 @@ zfs_getacl(znode_t *zp, vsecattr_t *vsecp, boolean_t skipaclchk, cred_t *cr)
 		return (SET_ERROR(ENOSYS));
 
 	if ((error = zfs_zaccess(zp, ACE_READ_ACL, 0, skipaclchk, cr,
-	    kcred->user_ns)))
+	    zfs_init_idmap)))
 		return (error);
 
 	mutex_enter(&zp->z_acl_lock);
@@ -2140,7 +2140,7 @@ zfs_setacl(znode_t *zp, vsecattr_t *vsecp, boolean_t skipaclchk, cred_t *cr)
 		return (SET_ERROR(EPERM));
 
 	if ((error = zfs_zaccess(zp, ACE_WRITE_ACL, 0, skipaclchk, cr,
-	    kcred->user_ns)))
+	    zfs_init_idmap)))
 		return (error);
 
 	error = zfs_vsec_2_aclp(zfsvfs, ZTOI(zp)->i_mode, vsecp, cr, &fuidp,
@@ -2286,7 +2286,7 @@ zfs_zaccess_dataset_check(znode_t *zp, uint32_t v4_mode)
  */
 static int
 zfs_zaccess_aces_check(znode_t *zp, uint32_t *working_mode,
-    boolean_t anyaccess, cred_t *cr, zuserns_t *mnt_ns)
+    boolean_t anyaccess, cred_t *cr, zidmap_t *mnt_ns)
 {
 	zfsvfs_t	*zfsvfs = ZTOZSB(zp);
 	zfs_acl_t	*aclp;
@@ -2420,7 +2420,7 @@ zfs_has_access(znode_t *zp, cred_t *cr)
 	uint32_t have = ACE_ALL_PERMS;
 
 	if (zfs_zaccess_aces_check(zp, &have, B_TRUE, cr,
-	    kcred->user_ns) != 0) {
+	    zfs_init_idmap) != 0) {
 		uid_t owner;
 
 		owner = zfs_fuid_map_id(ZTOZSB(zp),
@@ -2451,9 +2451,9 @@ zfs_has_access(znode_t *zp, cred_t *cr)
  */
 static int
 zfs_zaccess_trivial(znode_t *zp, uint32_t *working_mode, cred_t *cr,
-    zuserns_t *mnt_ns)
+    zidmap_t *mnt_ns)
 {
-	int err, mask;
+	int err, mask = 0;
 	int unmapped = 0;
 
 	ASSERT(zp->z_pflags & ZFS_ACL_TRIVIAL);
@@ -2464,11 +2464,10 @@ zfs_zaccess_trivial(znode_t *zp, uint32_t *working_mode, cred_t *cr,
 		return (unmapped ? SET_ERROR(EPERM) : 0);
 	}
 
-#if defined(HAVE_IOPS_PERMISSION_USERNS)
+#if (defined(HAVE_IOPS_PERMISSION_USERNS) || \
+	defined(HAVE_IOPS_PERMISSION_IDMAP))
 	if (mnt_ns)
 		err = generic_permission(mnt_ns, ZTOI(zp), mask);
-	else
-		err = generic_permission(cr->user_ns, ZTOI(zp), mask);
 #else
 	err = generic_permission(ZTOI(zp), mask);
 #endif
@@ -2483,7 +2482,7 @@ zfs_zaccess_trivial(znode_t *zp, uint32_t *working_mode, cred_t *cr,
 
 static int
 zfs_zaccess_common(znode_t *zp, uint32_t v4_mode, uint32_t *working_mode,
-    boolean_t *check_privs, boolean_t skipaclchk, cred_t *cr, zuserns_t *mnt_ns)
+    boolean_t *check_privs, boolean_t skipaclchk, cred_t *cr, zidmap_t *mnt_ns)
 {
 	zfsvfs_t *zfsvfs = ZTOZSB(zp);
 	int err;
@@ -2540,7 +2539,7 @@ zfs_zaccess_common(znode_t *zp, uint32_t v4_mode, uint32_t *working_mode,
 
 static int
 zfs_zaccess_append(znode_t *zp, uint32_t *working_mode, boolean_t *check_privs,
-    cred_t *cr, zuserns_t *mnt_ns)
+    cred_t *cr, zidmap_t *mnt_ns)
 {
 	if (*working_mode != ACE_WRITE_DATA)
 		return (SET_ERROR(EACCES));
@@ -2613,7 +2612,7 @@ zfs_fastaccesschk_execute(znode_t *zdp, cred_t *cr)
 	DTRACE_PROBE(zfs__fastpath__execute__access__miss);
 	ZFS_ENTER(ZTOZSB(zdp));
 	error = zfs_zaccess(zdp, ACE_EXECUTE, 0, B_FALSE, cr,
-	    kcred->user_ns);
+	    zfs_init_idmap);
 	ZFS_EXIT(ZTOZSB(zdp));
 	return (error);
 }
@@ -2626,7 +2625,7 @@ zfs_fastaccesschk_execute(znode_t *zdp, cred_t *cr)
  */
 int
 zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr,
-    zuserns_t *mnt_ns)
+    zidmap_t *mnt_ns)
 {
 	uint32_t	working_mode;
 	int		error;
@@ -2776,7 +2775,7 @@ zfs_zaccess(znode_t *zp, int mode, int flags, boolean_t skipaclchk, cred_t *cr,
  */
 int
 zfs_zaccess_rwx(znode_t *zp, mode_t mode, int flags, cred_t *cr,
-    zuserns_t *mnt_ns)
+    zidmap_t *mnt_ns)
 {
 	return (zfs_zaccess(zp, zfs_unix_to_v4(mode >> 6), flags, B_FALSE, cr,
 	    mnt_ns));
@@ -2786,11 +2785,11 @@ zfs_zaccess_rwx(znode_t *zp, mode_t mode, int flags, cred_t *cr,
  * Access function for secpolicy_vnode_setattr
  */
 int
-zfs_zaccess_unix(znode_t *zp, mode_t mode, cred_t *cr)
+zfs_zaccess_unix(void *zp, int mode, cred_t *cr)
 {
 	int v4_mode = zfs_unix_to_v4(mode >> 6);
 
-	return (zfs_zaccess(zp, v4_mode, 0, B_FALSE, cr, kcred->user_ns));
+	return (zfs_zaccess(zp, v4_mode, 0, B_FALSE, cr, zfs_init_idmap));
 }
 
 /* See zfs_zaccess_delete() */
@@ -2867,7 +2866,7 @@ int zfs_write_implies_delete_child = 1;
  * zfs_write_implies_delete_child
  */
 int
-zfs_zaccess_delete(znode_t *dzp, znode_t *zp, cred_t *cr, zuserns_t *mnt_ns)
+zfs_zaccess_delete(znode_t *dzp, znode_t *zp, cred_t *cr, zidmap_t *mnt_ns)
 {
 	uint32_t wanted_dirperms;
 	uint32_t dzp_working_mode = 0;
@@ -2998,7 +2997,7 @@ zfs_zaccess_delete(znode_t *dzp, znode_t *zp, cred_t *cr, zuserns_t *mnt_ns)
 
 int
 zfs_zaccess_rename(znode_t *sdzp, znode_t *szp, znode_t *tdzp,
-    znode_t *tzp, cred_t *cr, zuserns_t *mnt_ns)
+    znode_t *tzp, cred_t *cr, zidmap_t *mnt_ns)
 {
 	int add_perm;
 	int error;
diff --git a/module/os/linux/zfs/zfs_dir.c b/module/os/linux/zfs/zfs_dir.c
index 8c65c33628d..353e8805a8c 100644
--- a/module/os/linux/zfs/zfs_dir.c
+++ b/module/os/linux/zfs/zfs_dir.c
@@ -1067,7 +1067,7 @@ zfs_make_xattrdir(znode_t *zp, vattr_t *vap, znode_t **xzpp, cred_t *cr)
 	*xzpp = NULL;
 
 	if ((error = zfs_acl_ids_create(zp, IS_XATTR, vap, cr, NULL,
-	    &acl_ids, kcred->user_ns)) != 0)
+	    &acl_ids, zfs_init_idmap)) != 0)
 		return (error);
 	if (zfs_acl_ids_overquota(zfsvfs, &acl_ids, zp->z_projid)) {
 		zfs_acl_ids_free(&acl_ids);
@@ -1216,7 +1216,7 @@ zfs_sticky_remove_access(znode_t *zdp, znode_t *zp, cred_t *cr)
 
 	if ((uid = crgetuid(cr)) == downer || uid == fowner ||
 	    zfs_zaccess(zp, ACE_WRITE_DATA, 0, B_FALSE, cr,
-	    kcred->user_ns) == 0)
+	    zfs_init_idmap) == 0)
 		return (0);
 	else
 		return (secpolicy_vnode_remove(cr));
diff --git a/module/os/linux/zfs/zfs_ioctl_os.c b/module/os/linux/zfs/zfs_ioctl_os.c
index d70b31f9f10..5634a2514ae 100644
--- a/module/os/linux/zfs/zfs_ioctl_os.c
+++ b/module/os/linux/zfs/zfs_ioctl_os.c
@@ -290,6 +290,8 @@ zfsdev_detach(void)
 #define	ZFS_DEBUG_STR	""
 #endif
 
+zidmap_t *zfs_init_idmap;
+
 static int __init
 openzfs_init(void)
 {
@@ -313,6 +315,8 @@ openzfs_init(void)
 	printk(KERN_NOTICE "ZFS: Posix ACLs disabled by kernel\n");
 #endif /* CONFIG_FS_POSIX_ACL */
 
+	zfs_init_idmap = (zidmap_t *)zfs_get_init_idmap();
+
 	return (0);
 }
 
diff --git a/module/os/linux/zfs/zfs_vnops_os.c b/module/os/linux/zfs/zfs_vnops_os.c
index 23f3d140cf5..f8240ab7682 100644
--- a/module/os/linux/zfs/zfs_vnops_os.c
+++ b/module/os/linux/zfs/zfs_vnops_os.c
@@ -501,7 +501,7 @@ zfs_lookup(znode_t *zdp, char *nm, znode_t **zpp, int flags, cred_t *cr,
 		 */
 
 		if ((error = zfs_zaccess(*zpp, ACE_EXECUTE, 0,
-		    B_TRUE, cr, kcred->user_ns))) {
+		    B_TRUE, cr, zfs_init_idmap))) {
 			zrele(*zpp);
 			*zpp = NULL;
 		}
@@ -520,7 +520,7 @@ zfs_lookup(znode_t *zdp, char *nm, znode_t **zpp, int flags, cred_t *cr,
 	 */
 
 	if ((error = zfs_zaccess(zdp, ACE_EXECUTE, 0, B_FALSE, cr,
-	    kcred->user_ns))) {
+	    zfs_init_idmap))) {
 		ZFS_EXIT(zfsvfs);
 		return (error);
 	}
@@ -567,7 +567,7 @@ zfs_lookup(znode_t *zdp, char *nm, znode_t **zpp, int flags, cred_t *cr,
 int
 zfs_create(znode_t *dzp, char *name, vattr_t *vap, int excl,
     int mode, znode_t **zpp, cred_t *cr, int flag, vsecattr_t *vsecp,
-    zuserns_t *mnt_ns)
+    zidmap_t *mnt_ns)
 {
 	znode_t		*zp;
 	zfsvfs_t	*zfsvfs = ZTOZSB(dzp);
@@ -817,7 +817,7 @@ zfs_create(znode_t *dzp, char *name, vattr_t *vap, int excl,
 int
 zfs_tmpfile(struct inode *dip, vattr_t *vap, int excl,
     int mode, struct inode **ipp, cred_t *cr, int flag, vsecattr_t *vsecp,
-    zuserns_t *mnt_ns)
+    zidmap_t *mnt_ns)
 {
 	znode_t		*zp = NULL, *dzp = ITOZ(dip);
 	zfsvfs_t	*zfsvfs = ITOZSB(dip);
@@ -1002,7 +1002,7 @@ zfs_remove(znode_t *dzp, char *name, cred_t *cr, int flags)
 		return (error);
 	}
 
-	if ((error = zfs_zaccess_delete(dzp, zp, cr, kcred->user_ns))) {
+	if ((error = zfs_zaccess_delete(dzp, zp, cr, zfs_init_idmap))) {
 		goto out;
 	}
 
@@ -1196,7 +1196,7 @@ zfs_remove(znode_t *dzp, char *name, cred_t *cr, int flags)
 /*ARGSUSED*/
 int
 zfs_mkdir(znode_t *dzp, char *dirname, vattr_t *vap, znode_t **zpp,
-    cred_t *cr, int flags, vsecattr_t *vsecp, zuserns_t *mnt_ns)
+    cred_t *cr, int flags, vsecattr_t *vsecp, zidmap_t *mnt_ns)
 {
 	znode_t		*zp;
 	zfsvfs_t	*zfsvfs = ZTOZSB(dzp);
@@ -1418,7 +1418,7 @@ zfs_rmdir(znode_t *dzp, char *name, znode_t *cwd, cred_t *cr,
 		return (error);
 	}
 
-	if ((error = zfs_zaccess_delete(dzp, zp, cr, kcred->user_ns))) {
+	if ((error = zfs_zaccess_delete(dzp, zp, cr, zfs_init_idmap))) {
 		goto out;
 	}
 
@@ -1671,8 +1671,7 @@ zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr)
  */
 /* ARGSUSED */
 int
-zfs_getattr_fast(struct user_namespace *user_ns, struct inode *ip,
-    struct kstat *sp)
+zfs_getattr_fast(zidmap_t *user_ns, struct inode *ip, struct kstat *sp)
 {
 	znode_t *zp = ITOZ(ip);
 	zfsvfs_t *zfsvfs = ITOZSB(ip);
@@ -1860,7 +1859,7 @@ zfs_setattr_dir(znode_t *dzp)
  */
 /* ARGSUSED */
 int
-zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr, zuserns_t *mnt_ns)
+zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr, zidmap_t *mnt_ns)
 {
 	struct inode	*ip;
 	zfsvfs_t	*zfsvfs = ZTOZSB(zp);
@@ -2057,10 +2056,10 @@ zfs_setattr(znode_t *zp, vattr_t *vap, int flags, cred_t *cr, zuserns_t *mnt_ns)
 		 * Take ownership or chgrp to group we are a member of
 		 */
 
-		uid = zfs_uid_to_vfsuid((struct user_namespace *)mnt_ns,
-		    zfs_i_user_ns(ip), vap->va_uid);
-		gid = zfs_gid_to_vfsgid((struct user_namespace *)mnt_ns,
-		    zfs_i_user_ns(ip), vap->va_gid);
+		uid = zfs_uid_to_vfsuid(mnt_ns, zfs_i_user_ns(ip),
+		    vap->va_uid);
+		gid = zfs_gid_to_vfsgid(mnt_ns, zfs_i_user_ns(ip),
+		    vap->va_gid);
 		take_owner = (mask & ATTR_UID) && (uid == crgetuid(cr));
 		take_group = (mask & ATTR_GID) &&
 		    zfs_groupmember(zfsvfs, gid, cr);
@@ -2698,7 +2697,7 @@ zfs_rename_lock(znode_t *szp, znode_t *tdzp, znode_t *sdzp, zfs_zlock_t **zlpp)
 /*ARGSUSED*/
 int
 zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp, char *tnm,
-    cred_t *cr, int flags, zuserns_t *mnt_ns)
+    cred_t *cr, int flags, zidmap_t *mnt_ns)
 {
 	znode_t		*szp, *tzp;
 	zfsvfs_t	*zfsvfs = ZTOZSB(sdzp);
@@ -3067,7 +3066,7 @@ zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp, char *tnm,
 /*ARGSUSED*/
 int
 zfs_symlink(znode_t *dzp, char *name, vattr_t *vap, char *link,
-    znode_t **zpp, cred_t *cr, int flags, zuserns_t *mnt_ns)
+    znode_t **zpp, cred_t *cr, int flags, zidmap_t *mnt_ns)
 {
 	znode_t		*zp;
 	zfs_dirlock_t	*dl;
@@ -3373,7 +3372,7 @@ zfs_link(znode_t *tdzp, znode_t *szp, char *name, cred_t *cr,
 	}
 
 	if ((error = zfs_zaccess(tdzp, ACE_ADD_FILE, 0, B_FALSE, cr,
-	    kcred->user_ns))) {
+	    zfs_init_idmap))) {
 		ZFS_EXIT(zfsvfs);
 		return (error);
 	}
@@ -3962,7 +3961,7 @@ zfs_space(znode_t *zp, int cmd, flock64_t *bfp, int flag,
 	 * operates directly on inodes, so we need to check access rights.
 	 */
 	if ((error = zfs_zaccess(zp, ACE_WRITE_DATA, 0, B_FALSE, cr,
-	    kcred->user_ns))) {
+	    zfs_init_idmap))) {
 		ZFS_EXIT(zfsvfs);
 		return (error);
 	}
diff --git a/module/os/linux/zfs/zfs_znode.c b/module/os/linux/zfs/zfs_znode.c
index 5e820587388..4a1c6525aca 100644
--- a/module/os/linux/zfs/zfs_znode.c
+++ b/module/os/linux/zfs/zfs_znode.c
@@ -1947,7 +1947,7 @@ zfs_create_fs(objset_t *os, cred_t *cr, nvlist_t *zplprops, dmu_tx_t *tx)
 	}
 
 	VERIFY(0 == zfs_acl_ids_create(rootzp, IS_ROOT_NODE, &vattr,
-	    cr, NULL, &acl_ids, kcred->user_ns));
+	    cr, NULL, &acl_ids, zfs_init_idmap));
 	zfs_mknode(rootzp, &vattr, tx, cr, IS_ROOT_NODE, &zp, &acl_ids);
 	ASSERT3P(zp, ==, rootzp);
 	error = zap_add(os, moid, ZFS_ROOT_OBJ, 8, 1, &rootzp->z_id, tx);
diff --git a/module/os/linux/zfs/zpl_ctldir.c b/module/os/linux/zfs/zpl_ctldir.c
index e4f191ba051..1e1c35ed157 100644
--- a/module/os/linux/zfs/zpl_ctldir.c
+++ b/module/os/linux/zfs/zpl_ctldir.c
@@ -101,7 +101,11 @@ zpl_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
  */
 /* ARGSUSED */
 static int
-#ifdef HAVE_USERNS_IOPS_GETATTR
+#ifdef HAVE_IDMAP_IOPS_GETATTR
+zpl_root_getattr_impl(struct mnt_idmap *user_ns,
+    const struct path *path, struct kstat *stat, u32 request_mask,
+    unsigned int query_flags)
+#elif defined(HAVE_USERNS_IOPS_GETATTR)
 zpl_root_getattr_impl(struct user_namespace *user_ns,
     const struct path *path, struct kstat *stat, u32 request_mask,
     unsigned int query_flags)
@@ -112,8 +116,14 @@ zpl_root_getattr_impl(const struct path *path, struct kstat *stat,
 {
 	struct inode *ip = path->dentry->d_inode;
 
-#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
+#if (defined(HAVE_USERNS_IOPS_GETATTR) || defined(HAVE_IDMAP_IOPS_GETATTR))
+#ifdef HAVE_GENERIC_FILLATTR_USERNS
 	generic_fillattr(user_ns, ip, stat);
+#elif defined(HAVE_GENERIC_FILLATTR_IDMAP)
+	generic_fillattr(user_ns, ip, stat);
+#else
+	(void) user_ns;
+#endif
 #else
 	generic_fillattr(ip, stat);
 #endif
@@ -304,6 +314,10 @@ static int
 zpl_snapdir_rename2(struct user_namespace *user_ns, struct inode *sdip,
     struct dentry *sdentry, struct inode *tdip, struct dentry *tdentry,
     unsigned int flags)
+#elif defined(HAVE_IOPS_RENAME_IDMAP)
+zpl_snapdir_rename2(struct mnt_idmap *user_ns, struct inode *sdip,
+    struct dentry *sdentry, struct inode *tdip, struct dentry *tdentry,
+    unsigned int flags)
 #else
 zpl_snapdir_rename2(struct inode *sdip, struct dentry *sdentry,
     struct inode *tdip, struct dentry *tdentry, unsigned int flags)
@@ -325,7 +339,9 @@ zpl_snapdir_rename2(struct inode *sdip, struct dentry *sdentry,
 	return (error);
 }
 
-#if !defined(HAVE_RENAME_WANTS_FLAGS) && !defined(HAVE_IOPS_RENAME_USERNS)
+#if (!defined(HAVE_RENAME_WANTS_FLAGS) && \
+	!defined(HAVE_IOPS_RENAME_USERNS) && \
+	!defined(HAVE_IOPS_RENAME_IDMAP))
 static int
 zpl_snapdir_rename(struct inode *sdip, struct dentry *sdentry,
     struct inode *tdip, struct dentry *tdentry)
@@ -352,6 +368,9 @@ static int
 #ifdef HAVE_IOPS_MKDIR_USERNS
 zpl_snapdir_mkdir(struct user_namespace *user_ns, struct inode *dip,
     struct dentry *dentry, umode_t mode)
+#elif defined(HAVE_IOPS_MKDIR_IDMAP)
+zpl_snapdir_mkdir(struct mnt_idmap *user_ns, struct inode *dip,
+    struct dentry *dentry, umode_t mode)
 #else
 zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
 #endif
@@ -363,10 +382,10 @@ zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
 
 	crhold(cr);
 	vap = kmem_zalloc(sizeof (vattr_t), KM_SLEEP);
-#ifdef HAVE_IOPS_MKDIR_USERNS
+#if (defined(HAVE_IOPS_MKDIR_USERNS) || defined(HAVE_IOPS_MKDIR_IDMAP))
 	zpl_vap_init(vap, dip, mode | S_IFDIR, cr, user_ns);
 #else
-	zpl_vap_init(vap, dip, mode | S_IFDIR, cr, kcred->user_ns);
+	zpl_vap_init(vap, dip, mode | S_IFDIR, cr, zfs_init_idmap);
 #endif
 
 	error = -zfsctl_snapdir_mkdir(dip, dname(dentry), vap, &ip, cr, 0);
@@ -388,7 +407,11 @@ zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
  */
 /* ARGSUSED */
 static int
-#ifdef HAVE_USERNS_IOPS_GETATTR
+#ifdef HAVE_IDMAP_IOPS_GETATTR
+zpl_snapdir_getattr_impl(struct mnt_idmap *user_ns,
+    const struct path *path, struct kstat *stat, u32 request_mask,
+    unsigned int query_flags)
+#elif defined(HAVE_USERNS_IOPS_GETATTR)
 zpl_snapdir_getattr_impl(struct user_namespace *user_ns,
     const struct path *path, struct kstat *stat, u32 request_mask,
     unsigned int query_flags)
@@ -401,8 +424,14 @@ zpl_snapdir_getattr_impl(const struct path *path, struct kstat *stat,
 	zfsvfs_t *zfsvfs = ITOZSB(ip);
 
 	ZPL_ENTER(zfsvfs);
-#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
+#if (defined(HAVE_USERNS_IOPS_GETATTR) || defined(HAVE_IDMAP_IOPS_GETATTR))
+#ifdef HAVE_GENERIC_FILLATTR_USERNS
+	generic_fillattr(user_ns, ip, stat);
+#elif defined(HAVE_GENERIC_FILLATTR_IDMAP)
 	generic_fillattr(user_ns, ip, stat);
+#else
+	(void) user_ns;
+#endif
 #else
 	generic_fillattr(ip, stat);
 #endif
@@ -443,7 +472,9 @@ const struct file_operations zpl_fops_snapdir = {
 const struct inode_operations zpl_ops_snapdir = {
 	.lookup		= zpl_snapdir_lookup,
 	.getattr	= zpl_snapdir_getattr,
-#if defined(HAVE_RENAME_WANTS_FLAGS) || defined(HAVE_IOPS_RENAME_USERNS)
+#if (defined(HAVE_RENAME_WANTS_FLAGS) || \
+	defined(HAVE_IOPS_RENAME_USERNS) || \
+	defined(HAVE_IOPS_RENAME_IDMAP))
 	.rename		= zpl_snapdir_rename2,
 #else
 	.rename		= zpl_snapdir_rename,
@@ -534,6 +565,10 @@ static int
 zpl_shares_getattr_impl(struct user_namespace *user_ns,
     const struct path *path, struct kstat *stat, u32 request_mask,
     unsigned int query_flags)
+#elif defined(HAVE_IDMAP_IOPS_GETATTR)
+zpl_shares_getattr_impl(struct mnt_idmap *user_ns,
+    const struct path *path, struct kstat *stat, u32 request_mask,
+    unsigned int query_flags)
 #else
 zpl_shares_getattr_impl(const struct path *path, struct kstat *stat,
     u32 request_mask, unsigned int query_flags)
@@ -547,8 +582,14 @@ zpl_shares_getattr_impl(const struct path *path, struct kstat *stat,
 	ZPL_ENTER(zfsvfs);
 
 	if (zfsvfs->z_shares_dir == 0) {
-#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
+#if (defined(HAVE_USERNS_IOPS_GETATTR) || defined(HAVE_IDMAP_IOPS_GETATTR))
+#ifdef HAVE_GENERIC_FILLATTR_USERNS
+		generic_fillattr(user_ns, path->dentry->d_inode, stat);
+#elif defined(HAVE_GENERIC_FILLATTR_IDMAP)
 		generic_fillattr(user_ns, path->dentry->d_inode, stat);
+#else
+		(void) user_ns;
+#endif
 #else
 		generic_fillattr(path->dentry->d_inode, stat);
 #endif
@@ -560,7 +601,7 @@ zpl_shares_getattr_impl(const struct path *path, struct kstat *stat,
 
 	error = -zfs_zget(zfsvfs, zfsvfs->z_shares_dir, &dzp);
 	if (error == 0) {
-#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
+#if (defined(HAVE_USERNS_IOPS_GETATTR) || defined(HAVE_IDMAP_IOPS_GETATTR))
 		error = -zfs_getattr_fast(user_ns, ZTOI(dzp), stat);
 #else
 		error = -zfs_getattr_fast(kcred->user_ns, ZTOI(dzp), stat);
diff --git a/module/os/linux/zfs/zpl_file.c b/module/os/linux/zfs/zpl_file.c
index 4ad30efd3ec..f124599393f 100644
--- a/module/os/linux/zfs/zpl_file.c
+++ b/module/os/linux/zfs/zpl_file.c
@@ -924,7 +924,7 @@ __zpl_ioctl_setflags(struct inode *ip, uint32_t ioctl_flags, xvattr_t *xva)
 	    !capable(CAP_LINUX_IMMUTABLE))
 		return (-EPERM);
 
-	if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
+	if (!zpl_inode_owner_or_capable(zfs_init_idmap, ip))
 		return (-EACCES);
 
 	xva_init(xva);
@@ -971,7 +971,7 @@ zpl_ioctl_setflags(struct file *filp, void __user *arg)
 
 	crhold(cr);
 	cookie = spl_fstrans_mark();
-	err = -zfs_setattr(ITOZ(ip), (vattr_t *)&xva, 0, cr, kcred->user_ns);
+	err = -zfs_setattr(ITOZ(ip), (vattr_t *)&xva, 0, cr, zfs_init_idmap);
 	spl_fstrans_unmark(cookie);
 	crfree(cr);
 
@@ -1019,7 +1019,7 @@ zpl_ioctl_setxattr(struct file *filp, void __user *arg)
 
 	crhold(cr);
 	cookie = spl_fstrans_mark();
-	err = -zfs_setattr(ITOZ(ip), (vattr_t *)&xva, 0, cr, kcred->user_ns);
+	err = -zfs_setattr(ITOZ(ip), (vattr_t *)&xva, 0, cr, zfs_init_idmap);
 	spl_fstrans_unmark(cookie);
 	crfree(cr);
 
@@ -1054,7 +1054,7 @@ __zpl_ioctl_setdosflags(struct inode *ip, uint64_t ioctl_flags, xvattr_t *xva)
 	    !capable(CAP_LINUX_IMMUTABLE))
 		return (-EPERM);
 
-	if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
+	if (!zpl_inode_owner_or_capable(zfs_init_idmap, ip))
 		return (-EACCES);
 
 	xva_init(xva);
@@ -1107,7 +1107,7 @@ zpl_ioctl_setdosflags(struct file *filp, void __user *arg)
 
 	crhold(cr);
 	cookie = spl_fstrans_mark();
-	err = -zfs_setattr(ITOZ(ip), (vattr_t *)&xva, 0, cr, kcred->user_ns);
+	err = -zfs_setattr(ITOZ(ip), (vattr_t *)&xva, 0, cr, zfs_init_idmap);
 	spl_fstrans_unmark(cookie);
 	crfree(cr);
 
diff --git a/module/os/linux/zfs/zpl_inode.c b/module/os/linux/zfs/zpl_inode.c
index ea659d9618a..01bcfc19f2b 100644
--- a/module/os/linux/zfs/zpl_inode.c
+++ b/module/os/linux/zfs/zpl_inode.c
@@ -112,12 +112,12 @@ zpl_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags)
 
 void
 zpl_vap_init(vattr_t *vap, struct inode *dir, umode_t mode, cred_t *cr,
-    zuserns_t *mnt_ns)
+    zidmap_t *mnt_ns)
 {
 	vap->va_mask = ATTR_MODE;
 	vap->va_mode = mode;
 
-	vap->va_uid = zfs_vfsuid_to_uid((struct user_namespace *)mnt_ns,
+	vap->va_uid = zfs_vfsuid_to_uid(mnt_ns,
 	    zfs_i_user_ns(dir), crgetuid(cr));
 
 	if (dir && dir->i_mode & S_ISGID) {
@@ -125,7 +125,7 @@ zpl_vap_init(vattr_t *vap, struct inode *dir, umode_t mode, cred_t *cr,
 		if (S_ISDIR(mode))
 			vap->va_mode |= S_ISGID;
 	} else {
-		vap->va_gid = zfs_vfsgid_to_gid((struct user_namespace *)mnt_ns,
+		vap->va_gid = zfs_vfsgid_to_gid(mnt_ns,
 		    zfs_i_user_ns(dir), crgetgid(cr));
 	}
 }
@@ -134,6 +134,9 @@ static int
 #ifdef HAVE_IOPS_CREATE_USERNS
 zpl_create(struct user_namespace *user_ns, struct inode *dir,
     struct dentry *dentry, umode_t mode, bool flag)
+#elif defined(HAVE_IOPS_CREATE_IDMAP)
+zpl_create(struct mnt_idmap *user_ns, struct inode *dir,
+    struct dentry *dentry, umode_t mode, bool flag)
 #else
 zpl_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool flag)
 #endif
@@ -143,8 +146,8 @@ zpl_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool flag)
 	vattr_t *vap;
 	int error;
 	fstrans_cookie_t cookie;
-#ifndef HAVE_IOPS_CREATE_USERNS
-	zuserns_t *user_ns = kcred->user_ns;
+#if !(defined(HAVE_IOPS_CREATE_USERNS) || defined(HAVE_IOPS_CREATE_IDMAP))
+	zidmap_t *user_ns = kcred->user_ns;
 #endif
 
 	crhold(cr);
@@ -180,6 +183,9 @@ static int
 #ifdef HAVE_IOPS_MKNOD_USERNS
 zpl_mknod(struct user_namespace *user_ns, struct inode *dir,
     struct dentry *dentry, umode_t mode,
+#elif defined(HAVE_IOPS_MKNOD_IDMAP)
+zpl_mknod(struct mnt_idmap *user_ns, struct inode *dir,
+    struct dentry *dentry, umode_t mode,
 #else
 zpl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 #endif
@@ -190,8 +196,8 @@ zpl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 	vattr_t *vap;
 	int error;
 	fstrans_cookie_t cookie;
-#ifndef HAVE_IOPS_MKNOD_USERNS
-	zuserns_t *user_ns = kcred->user_ns;
+#if !(defined(HAVE_IOPS_MKNOD_USERNS) || defined(HAVE_IOPS_MKNOD_IDMAP))
+	zidmap_t *user_ns = kcred->user_ns;
 #endif
 
 	/*
@@ -233,7 +239,10 @@ zpl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
 
 #ifdef HAVE_TMPFILE
 static int
-#ifndef HAVE_TMPFILE_DENTRY
+#ifdef HAVE_TMPFILE_IDMAP
+zpl_tmpfile(struct mnt_idmap *userns, struct inode *dir,
+    struct file *file, umode_t mode)
+#elif !defined(HAVE_TMPFILE_DENTRY)
 zpl_tmpfile(struct user_namespace *userns, struct inode *dir,
     struct file *file, umode_t mode)
 #else
@@ -250,8 +259,8 @@ zpl_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 	vattr_t *vap;
 	int error;
 	fstrans_cookie_t cookie;
-#ifndef HAVE_TMPFILE_USERNS
-	zuserns_t *userns = kcred->user_ns;
+#if !(defined(HAVE_TMPFILE_USERNS) || defined(HAVE_TMPFILE_IDMAP))
+	zidmap_t *userns = kcred->user_ns;
 #endif
 
 	crhold(cr);
@@ -329,6 +338,9 @@ static int
 #ifdef HAVE_IOPS_MKDIR_USERNS
 zpl_mkdir(struct user_namespace *user_ns, struct inode *dir,
     struct dentry *dentry, umode_t mode)
+#elif defined(HAVE_IOPS_MKDIR_IDMAP)
+zpl_mkdir(struct mnt_idmap *user_ns, struct inode *dir,
+    struct dentry *dentry, umode_t mode)
 #else
 zpl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 #endif
@@ -338,8 +350,8 @@ zpl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 	znode_t *zp;
 	int error;
 	fstrans_cookie_t cookie;
-#ifndef HAVE_IOPS_MKDIR_USERNS
-	zuserns_t *user_ns = kcred->user_ns;
+#if !(defined(HAVE_IOPS_MKDIR_USERNS) || defined(HAVE_IOPS_MKDIR_IDMAP))
+	zidmap_t *user_ns = kcred->user_ns;
 #endif
 
 	crhold(cr);
@@ -402,6 +414,10 @@ static int
 zpl_getattr_impl(struct user_namespace *user_ns,
     const struct path *path, struct kstat *stat, u32 request_mask,
     unsigned int query_flags)
+#elif defined(HAVE_IDMAP_IOPS_GETATTR)
+zpl_getattr_impl(struct mnt_idmap *user_ns,
+    const struct path *path, struct kstat *stat, u32 request_mask,
+    unsigned int query_flags)
 #else
 zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
     unsigned int query_flags)
@@ -418,7 +434,7 @@ zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
 	 * XXX query_flags currently ignored.
 	 */
 
-#ifdef HAVE_USERNS_IOPS_GETATTR
+#if (defined(HAVE_USERNS_IOPS_GETATTR) || defined(HAVE_IDMAP_IOPS_GETATTR))
 	error = -zfs_getattr_fast(user_ns, ip, stat);
 #else
 	error = -zfs_getattr_fast(kcred->user_ns, ip, stat);
@@ -457,9 +473,12 @@ zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
 ZPL_GETATTR_WRAPPER(zpl_getattr);
 
 static int
-#ifdef HAVE_SETATTR_PREPARE_USERNS
+#ifdef HAVE_USERNS_IOPS_SETATTR
 zpl_setattr(struct user_namespace *user_ns, struct dentry *dentry,
     struct iattr *ia)
+#elif defined(HAVE_IDMAP_IOPS_SETATTR)
+zpl_setattr(struct mnt_idmap *user_ns, struct dentry *dentry,
+    struct iattr *ia)
 #else
 zpl_setattr(struct dentry *dentry, struct iattr *ia)
 #endif
@@ -472,8 +491,10 @@ zpl_setattr(struct dentry *dentry, struct iattr *ia)
 
 #ifdef HAVE_SETATTR_PREPARE_USERNS
 	error = zpl_setattr_prepare(user_ns, dentry, ia);
+#elif defined(HAVE_SETATTR_PREPARE_IDMAP)
+	error = zpl_setattr_prepare(user_ns, dentry, ia);
 #else
-	error = zpl_setattr_prepare(kcred->user_ns, dentry, ia);
+	error = zpl_setattr_prepare(zfs_init_idmap, dentry, ia);
 #endif
 	if (error)
 		return (error);
@@ -505,10 +526,12 @@ zpl_setattr(struct dentry *dentry, struct iattr *ia)
 		ip->i_atime = zpl_inode_timestamp_truncate(ia->ia_atime, ip);
 
 	cookie = spl_fstrans_mark();
-#ifdef HAVE_SETATTR_PREPARE_USERNS
+#ifdef HAVE_USERNS_IOPS_SETATTR
+	error = -zfs_setattr(ITOZ(ip), vap, 0, cr, user_ns);
+#elif defined(HAVE_IDMAP_IOPS_SETATTR)
 	error = -zfs_setattr(ITOZ(ip), vap, 0, cr, user_ns);
 #else
-	error = -zfs_setattr(ITOZ(ip), vap, 0, cr, kcred->user_ns);
+	error = -zfs_setattr(ITOZ(ip), vap, 0, cr, zfs_init_idmap);
 #endif
 	if (!error && (ia->ia_valid & ATTR_MODE))
 		error = zpl_chmod_acl(ip);
@@ -526,6 +549,10 @@ static int
 zpl_rename2(struct user_namespace *user_ns, struct inode *sdip,
     struct dentry *sdentry, struct inode *tdip, struct dentry *tdentry,
     unsigned int flags)
+#elif defined(HAVE_IOPS_RENAME_IDMAP)
+zpl_rename2(struct mnt_idmap *user_ns, struct inode *sdip,
+    struct dentry *sdentry, struct inode *tdip, struct dentry *tdentry,
+    unsigned int flags)
 #else
 zpl_rename2(struct inode *sdip, struct dentry *sdentry,
     struct inode *tdip, struct dentry *tdentry, unsigned int flags)
@@ -534,8 +561,8 @@ zpl_rename2(struct inode *sdip, struct dentry *sdentry,
 	cred_t *cr = CRED();
 	int error;
 	fstrans_cookie_t cookie;
-#ifndef HAVE_IOPS_RENAME_USERNS
-	zuserns_t *user_ns = kcred->user_ns;
+#if !(defined(HAVE_IOPS_RENAME_USERNS) || defined(HAVE_IOPS_RENAME_IDMAP))
+	zidmap_t *user_ns = kcred->user_ns;
 #endif
 
 	/* We don't have renameat2(2) support */
@@ -553,7 +580,10 @@ zpl_rename2(struct inode *sdip, struct dentry *sdentry,
 	return (error);
 }
 
-#if !defined(HAVE_RENAME_WANTS_FLAGS) && !defined(HAVE_IOPS_RENAME_USERNS)
+#if !defined(HAVE_IOPS_RENAME_USERNS) && \
+	!defined(HAVE_RENAME_WANTS_FLAGS) && \
+	!defined(HAVE_RENAME2) && \
+	!defined(HAVE_IOPS_RENAME_IDMAP)
 static int
 zpl_rename(struct inode *sdip, struct dentry *sdentry,
     struct inode *tdip, struct dentry *tdentry)
@@ -566,6 +596,9 @@ static int
 #ifdef HAVE_IOPS_SYMLINK_USERNS
 zpl_symlink(struct user_namespace *user_ns, struct inode *dir,
     struct dentry *dentry, const char *name)
+#elif defined(HAVE_IOPS_SYMLINK_IDMAP)
+zpl_symlink(struct mnt_idmap *user_ns, struct inode *dir,
+    struct dentry *dentry, const char *name)
 #else
 zpl_symlink(struct inode *dir, struct dentry *dentry, const char *name)
 #endif
@@ -575,8 +608,8 @@ zpl_symlink(struct inode *dir, struct dentry *dentry, const char *name)
 	znode_t *zp;
 	int error;
 	fstrans_cookie_t cookie;
-#ifndef HAVE_IOPS_SYMLINK_USERNS
-	zuserns_t *user_ns = kcred->user_ns;
+#if !(defined(HAVE_IOPS_SYMLINK_USERNS) || defined(HAVE_IOPS_SYMLINK_IDMAP))
+	zidmap_t *user_ns = kcred->user_ns;
 #endif
 
 	crhold(cr);
@@ -787,6 +820,8 @@ const struct inode_operations zpl_dir_inode_operations = {
 	.mknod		= zpl_mknod,
 #if defined(HAVE_RENAME_WANTS_FLAGS) || defined(HAVE_IOPS_RENAME_USERNS)
 	.rename		= zpl_rename2,
+#elif defined(HAVE_IOPS_RENAME_IDMAP)
+	.rename		= zpl_rename2,
 #else
 	.rename		= zpl_rename,
 #endif
diff --git a/module/os/linux/zfs/zpl_xattr.c b/module/os/linux/zfs/zpl_xattr.c
index b377651bad4..bffc86b3006 100644
--- a/module/os/linux/zfs/zpl_xattr.c
+++ b/module/os/linux/zfs/zpl_xattr.c
@@ -496,7 +496,7 @@ zpl_xattr_set_dir(struct inode *ip, const char *name, const void *value,
 		vap->va_gid = crgetgid(cr);
 
 		error = -zfs_create(dxzp, (char *)name, vap, 0, 0644, &xzp,
-		    cr, 0, NULL, kcred->user_ns);
+		    cr, ATTR_NOACLCHECK, NULL, zfs_init_idmap);
 		if (error)
 			goto out;
 	}
@@ -725,7 +725,7 @@ __zpl_xattr_user_get(struct inode *ip, const char *name,
 ZPL_XATTR_GET_WRAPPER(zpl_xattr_user_get);
 
 static int
-__zpl_xattr_user_set(struct user_namespace *user_ns,
+__zpl_xattr_user_set(zidmap_t *user_ns,
     struct inode *ip, const char *name,
     const void *value, size_t size, int flags)
 {
@@ -796,7 +796,7 @@ __zpl_xattr_trusted_get(struct inode *ip, const char *name,
 ZPL_XATTR_GET_WRAPPER(zpl_xattr_trusted_get);
 
 static int
-__zpl_xattr_trusted_set(struct user_namespace *user_ns,
+__zpl_xattr_trusted_set(zidmap_t *user_ns,
     struct inode *ip, const char *name,
     const void *value, size_t size, int flags)
 {
@@ -867,7 +867,7 @@ __zpl_xattr_security_get(struct inode *ip, const char *name,
 ZPL_XATTR_GET_WRAPPER(zpl_xattr_security_get);
 
 static int
-__zpl_xattr_security_set(struct user_namespace *user_ns,
+__zpl_xattr_security_set(zidmap_t *user_ns,
     struct inode *ip, const char *name,
     const void *value, size_t size, int flags)
 {
@@ -1010,6 +1010,9 @@ int
 #ifdef HAVE_SET_ACL_USERNS
 zpl_set_acl(struct user_namespace *userns, struct inode *ip,
     struct posix_acl *acl, int type)
+#elif defined(HAVE_SET_ACL_IDMAP_DENTRY)
+zpl_set_acl(struct mnt_idmap *userns, struct dentry *dentry,
+    struct posix_acl *acl, int type)
 #elif defined(HAVE_SET_ACL_USERNS_DENTRY_ARG2)
 zpl_set_acl(struct user_namespace *userns, struct dentry *dentry,
     struct posix_acl *acl, int type)
@@ -1019,6 +1022,8 @@ zpl_set_acl(struct inode *ip, struct posix_acl *acl, int type)
 {
 #ifdef HAVE_SET_ACL_USERNS_DENTRY_ARG2
 	return (zpl_set_acl_impl(d_inode(dentry), acl, type));
+#elif defined(HAVE_SET_ACL_IDMAP_DENTRY)
+	return (zpl_set_acl_impl(d_inode(dentry), acl, type));
 #else
 	return (zpl_set_acl_impl(ip, acl, type));
 #endif /* HAVE_SET_ACL_USERNS_DENTRY_ARG2 */
@@ -1262,7 +1267,7 @@ __zpl_xattr_acl_get_default(struct inode *ip, const char *name,
 ZPL_XATTR_GET_WRAPPER(zpl_xattr_acl_get_default);
 
 static int
-__zpl_xattr_acl_set_access(struct user_namespace *mnt_ns,
+__zpl_xattr_acl_set_access(zidmap_t *mnt_ns,
     struct inode *ip, const char *name,
     const void *value, size_t size, int flags)
 {
@@ -1277,12 +1282,12 @@ __zpl_xattr_acl_set_access(struct user_namespace *mnt_ns,
 	if (ITOZSB(ip)->z_acl_type != ZFS_ACLTYPE_POSIX)
 		return (-EOPNOTSUPP);
 
-#if defined(HAVE_XATTR_SET_USERNS)
+#if defined(HAVE_XATTR_SET_USERNS) || defined(HAVE_XATTR_SET_IDMAP)
 	if (!zpl_inode_owner_or_capable(mnt_ns, ip))
 		return (-EPERM);
 #else
 	(void) mnt_ns;
-	if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
+	if (!zpl_inode_owner_or_capable(zfs_init_idmap, ip))
 		return (-EPERM);
 #endif
 
@@ -1308,7 +1313,7 @@ __zpl_xattr_acl_set_access(struct user_namespace *mnt_ns,
 ZPL_XATTR_SET_WRAPPER(zpl_xattr_acl_set_access);
 
 static int
-__zpl_xattr_acl_set_default(struct user_namespace *mnt_ns,
+__zpl_xattr_acl_set_default(zidmap_t *mnt_ns,
     struct inode *ip, const char *name,
     const void *value, size_t size, int flags)
 {
@@ -1323,12 +1328,12 @@ __zpl_xattr_acl_set_default(struct user_namespace *mnt_ns,
 	if (ITOZSB(ip)->z_acl_type != ZFS_ACLTYPE_POSIX)
 		return (-EOPNOTSUPP);
 
-#if defined(HAVE_XATTR_SET_USERNS)
+#if defined(HAVE_XATTR_SET_USERNS) || defined(HAVE_XATTR_SET_IDMAP)
 	if (!zpl_inode_owner_or_capable(mnt_ns, ip))
 		return (-EPERM);
 #else
 	(void) mnt_ns;
-	if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
+	if (!zpl_inode_owner_or_capable(zfs_init_idmap, ip))
 		return (-EPERM);
 #endif
 
diff --git a/module/zfs/zfs_replay.c b/module/zfs/zfs_replay.c
index 755bbc6cd98..db5aefbe104 100644
--- a/module/zfs/zfs_replay.c
+++ b/module/zfs/zfs_replay.c
@@ -386,7 +386,7 @@ zfs_replay_create_acl(void *arg1, void *arg2, boolean_t byteswap)
 
 #if defined(__linux__)
 		error = zfs_create(dzp, name, &xva.xva_vattr,
-		    0, 0, &zp, kcred, vflg, &vsec, kcred->user_ns);
+		    0, 0, &zp, kcred, vflg, &vsec, zfs_init_idmap);
 #else
 		error = zfs_create(dzp, name, &xva.xva_vattr,
 		    0, 0, &zp, kcred, vflg, &vsec, NULL);
@@ -421,7 +421,7 @@ zfs_replay_create_acl(void *arg1, void *arg2, boolean_t byteswap)
 		}
 #if defined(__linux__)
 		error = zfs_mkdir(dzp, name, &xva.xva_vattr,
-		    &zp, kcred, vflg, &vsec, kcred->user_ns);
+		    &zp, kcred, vflg, &vsec, zfs_init_idmap);
 #else
 		error = zfs_mkdir(dzp, name, &xva.xva_vattr,
 		    &zp, kcred, vflg, &vsec, NULL);
@@ -536,7 +536,7 @@ zfs_replay_create(void *arg1, void *arg2, boolean_t byteswap)
 
 #if defined(__linux__)
 		error = zfs_create(dzp, name, &xva.xva_vattr,
-		    0, 0, &zp, kcred, vflg, NULL, kcred->user_ns);
+		    0, 0, &zp, kcred, vflg, NULL, zfs_init_idmap);
 #else
 		error = zfs_create(dzp, name, &xva.xva_vattr,
 		    0, 0, &zp, kcred, vflg, NULL, NULL);
@@ -558,7 +558,7 @@ zfs_replay_create(void *arg1, void *arg2, boolean_t byteswap)
 
 #if defined(__linux__)
 		error = zfs_mkdir(dzp, name, &xva.xva_vattr,
-		    &zp, kcred, vflg, NULL, kcred->user_ns);
+		    &zp, kcred, vflg, NULL, zfs_init_idmap);
 #else
 		error = zfs_mkdir(dzp, name, &xva.xva_vattr,
 		    &zp, kcred, vflg, NULL, NULL);
@@ -573,7 +573,7 @@ zfs_replay_create(void *arg1, void *arg2, boolean_t byteswap)
 		link = name + strlen(name) + 1;
 #if defined(__linux__)
 		error = zfs_symlink(dzp, name, &xva.xva_vattr,
-		    link, &zp, kcred, vflg, kcred->user_ns);
+		    link, &zp, kcred, vflg, zfs_init_idmap);
 #else
 		error = zfs_symlink(dzp, name, &xva.xva_vattr,
 		    link, &zp, kcred, vflg, NULL);
@@ -691,7 +691,7 @@ zfs_replay_rename(void *arg1, void *arg2, boolean_t byteswap)
 
 #if defined(__linux__)
 	error = zfs_rename(sdzp, sname, tdzp, tname, kcred, vflg,
-	    kcred->user_ns);
+	    zfs_init_idmap);
 #else
 	error = zfs_rename(sdzp, sname, tdzp, tname, kcred, vflg,
 	    NULL);
@@ -890,7 +890,7 @@ zfs_replay_setattr(void *arg1, void *arg2, boolean_t byteswap)
 	    lr->lr_uid, lr->lr_gid);
 
 #if defined(__linux__)
-	error = zfs_setattr(zp, vap, 0, kcred, kcred->user_ns);
+	error = zfs_setattr(zp, vap, 0, kcred, zfs_init_idmap);
 #else
 	error = zfs_setattr(zp, vap, 0, kcred, NULL);
 #endif
diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index 2b6d35282a0..7590a985266 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -167,14 +167,14 @@ zfs_access(znode_t *zp, int mode, int flag, cred_t *cr)
 	if (flag & V_ACE_MASK)
 #if defined(__linux__)
 		error = zfs_zaccess(zp, mode, flag, B_FALSE, cr,
-		    kcred->user_ns);
+		    zfs_init_idmap);
 #else
 		error = zfs_zaccess(zp, mode, flag, B_FALSE, cr,
 		    NULL);
 #endif
 	else
 #if defined(__linux__)
-		error = zfs_zaccess_rwx(zp, mode, flag, cr, kcred->user_ns);
+		error = zfs_zaccess_rwx(zp, mode, flag, cr, zfs_init_idmap);
 #else
 		error = zfs_zaccess_rwx(zp, mode, flag, cr, NULL);
 #endif