diff --git a/config/kernel-bio_max_segs.m4 b/config/kernel-bio_max_segs.m4
new file mode 100644
index 00000000000..a90d75455c1
--- /dev/null
+++ b/config/kernel-bio_max_segs.m4
@@ -0,0 +1,23 @@
+dnl #
+dnl # 5.12 API change removes BIO_MAX_PAGES in favor of bio_max_segs()
+dnl # which will handle the logic of setting the upper-bound to a
+dnl # BIO_MAX_PAGES, internally.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_BIO_MAX_SEGS], [
+	ZFS_LINUX_TEST_SRC([bio_max_segs], [
+		#include <linux/bio.h>
+	],[
+		bio_max_segs(1);
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_BIO_MAX_SEGS], [
+	AC_MSG_CHECKING([whether bio_max_segs() exists])
+	ZFS_LINUX_TEST_RESULT([bio_max_segs], [
+		AC_MSG_RESULT(yes)
+
+		AC_DEFINE([HAVE_BIO_MAX_SEGS], 1, [bio_max_segs() is implemented])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
diff --git a/config/kernel-generic_fillattr.m4 b/config/kernel-generic_fillattr.m4
new file mode 100644
index 00000000000..50c8031305b
--- /dev/null
+++ b/config/kernel-generic_fillattr.m4
@@ -0,0 +1,28 @@
+dnl #
+dnl # 5.12 API
+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], [
+	ZFS_LINUX_TEST_SRC([generic_fillattr_userns], [
+		#include <linux/fs.h>
+	],[
+		struct user_namespace *userns = NULL;
+		struct inode *in = NULL;
+		struct kstat *k = NULL;
+		generic_fillattr(userns, in, k);
+	])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_GENERIC_FILLATTR_USERNS], [
+	AC_MSG_CHECKING([whether generic_fillattr requres 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 9f28bcbd4f7..a6ea11fb61b 100644
--- a/config/kernel-inode-create.m4
+++ b/config/kernel-inode-create.m4
@@ -1,7 +1,25 @@
-dnl #
-dnl # 3.6 API change
-dnl #
-AC_DEFUN([ZFS_AC_KERNEL_SRC_CREATE_FLAGS], [
+AC_DEFUN([ZFS_AC_KERNEL_SRC_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.
+	dnl #
+	ZFS_LINUX_TEST_SRC([create_userns], [
+		#include <linux/fs.h>
+		#include <linux/sched.h>
+
+		int inode_create(struct user_namespace *userns,
+		    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 # 3.6 API change
+	dnl #
 	ZFS_LINUX_TEST_SRC([create_flags], [
 		#include <linux/fs.h>
 		#include <linux/sched.h>
@@ -16,11 +34,20 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_CREATE_FLAGS], [
 	],[])
 ])
 
-AC_DEFUN([ZFS_AC_KERNEL_CREATE_FLAGS], [
-	AC_MSG_CHECKING([whether iops->create() passes flags])
-	ZFS_LINUX_TEST_RESULT([create_flags], [
+AC_DEFUN([ZFS_AC_KERNEL_CREATE], [
+	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 48391d66f8b..f62e82f5230 100644
--- a/config/kernel-inode-getattr.m4
+++ b/config/kernel-inode-getattr.m4
@@ -1,8 +1,29 @@
-dnl #
-dnl # Linux 4.11 API
-dnl # See torvalds/linux@a528d35
-dnl #
 AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_GETATTR], [
+	dnl #
+	dnl # Linux 5.12 API
+	dnl # The getattr 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_getattr_userns], [
+		#include <linux/fs.h>
+
+		int test_getattr(
+			struct user_namespace *userns,
+		    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 4.11 API
+	dnl # See torvalds/linux@a528d35
+	dnl #
 	ZFS_LINUX_TEST_SRC([inode_operations_getattr_path], [
 		#include <linux/fs.h>
 
@@ -33,21 +54,39 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_GETATTR], [
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_INODE_GETATTR], [
-	AC_MSG_CHECKING([whether iops->getattr() takes a path])
-	ZFS_LINUX_TEST_RESULT([inode_operations_getattr_path], [
+	dnl #
+	dnl # Kernel 5.12 test
+	dnl #
+	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)
 
-		AC_MSG_CHECKING([whether iops->getattr() takes a vfsmount])
-		ZFS_LINUX_TEST_RESULT([inode_operations_getattr_vfsmount], [
+		dnl #
+		dnl # Kernel 4.11 test
+		dnl #
+		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-is_owner_or_cap.m4 b/config/kernel-is_owner_or_cap.m4
index 3df6163da27..3c3c6ad2240 100644
--- a/config/kernel-is_owner_or_cap.m4
+++ b/config/kernel-is_owner_or_cap.m4
@@ -11,13 +11,32 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_INODE_OWNER_OR_CAPABLE], [
 		struct inode *ip = NULL;
 		(void) inode_owner_or_capable(ip);
 	])
+
+	ZFS_LINUX_TEST_SRC([inode_owner_or_capable_idmapped], [
+		#include <linux/fs.h>
+	],[
+		struct inode *ip = NULL;
+		(void) inode_owner_or_capable(&init_user_ns, ip);
+	])
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_INODE_OWNER_OR_CAPABLE], [
 	AC_MSG_CHECKING([whether inode_owner_or_capable() exists])
 	ZFS_LINUX_TEST_RESULT([inode_owner_or_capable], [
 		AC_MSG_RESULT(yes)
-	],[
-		ZFS_LINUX_TEST_ERROR([capability])
+		AC_DEFINE(HAVE_INODE_OWNER_OR_CAPABLE, 1,
+		    [inode_owner_or_capable() exists])
+	], [
+		AC_MSG_RESULT(no)
+
+		AC_MSG_CHECKING(
+		    [whether inode_owner_or_capable() takes user_ns])
+		ZFS_LINUX_TEST_RESULT([inode_owner_or_capable_idmapped], [
+			AC_MSG_RESULT(yes)
+			AC_DEFINE(HAVE_INODE_OWNER_OR_CAPABLE_IDMAPPED, 1,
+			    [inode_owner_or_capable() takes user_ns])
+		],[
+			ZFS_LINUX_TEST_ERROR([capability])
+		])
 	])
 ])
diff --git a/config/kernel-mkdir-umode-t.m4 b/config/kernel-mkdir-umode-t.m4
deleted file mode 100644
index 19599670df3..00000000000
--- a/config/kernel-mkdir-umode-t.m4
+++ /dev/null
@@ -1,32 +0,0 @@
-dnl #
-dnl # 3.3 API change
-dnl # The VFS .create, .mkdir and .mknod callbacks were updated to take a
-dnl # umode_t type rather than an int.  The expectation is that any backport
-dnl # would also change all three prototypes.  However, if it turns out that
-dnl # some distribution doesn't backport the whole thing this could be
-dnl # broken apart into three separate checks.
-dnl #
-AC_DEFUN([ZFS_AC_KERNEL_SRC_MKDIR_UMODE_T], [
-	ZFS_LINUX_TEST_SRC([inode_operations_mkdir], [
-		#include <linux/fs.h>
-
-		int mkdir(struct inode *inode, struct dentry *dentry,
-		    umode_t umode) { return 0; }
-
-		static const struct inode_operations
-		    iops __attribute__ ((unused)) = {
-			.mkdir = mkdir,
-		};
-	],[])
-])
-
-AC_DEFUN([ZFS_AC_KERNEL_MKDIR_UMODE_T], [
-	AC_MSG_CHECKING([whether iops->create()/mkdir()/mknod() take umode_t])
-	ZFS_LINUX_TEST_RESULT([inode_operations_mkdir], [
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_MKDIR_UMODE_T, 1,
-		    [iops->create()/mkdir()/mknod() take umode_t])
-	],[
-		ZFS_LINUX_TEST_ERROR([mkdir()])
-	])
-])
diff --git a/config/kernel-mkdir.m4 b/config/kernel-mkdir.m4
new file mode 100644
index 00000000000..a162bcd880f
--- /dev/null
+++ b/config/kernel-mkdir.m4
@@ -0,0 +1,65 @@
+dnl #
+dnl # Supported mkdir() interfaces checked newest to oldest.
+dnl #
+AC_DEFUN([ZFS_AC_KERNEL_SRC_MKDIR], [
+	dnl #
+	dnl # 5.12 API change
+	dnl # The struct user_namespace arg was added as the first argument to
+	dnl # mkdir()
+	dnl #
+	ZFS_LINUX_TEST_SRC([mkdir_user_namespace], [
+		#include <linux/fs.h>
+
+		int mkdir(struct user_namespace *userns,
+			struct inode *inode, struct dentry *dentry,
+		    umode_t umode) { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.mkdir = mkdir,
+		};
+	],[])
+
+	dnl #
+	dnl # 3.3 API change
+	dnl # The VFS .create, .mkdir and .mknod callbacks were updated to take a
+	dnl # umode_t type rather than an int.  The expectation is that any backport
+	dnl # would also change all three prototypes.  However, if it turns out that
+	dnl # some distribution doesn't backport the whole thing this could be
+	dnl # broken apart into three separate checks.
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_operations_mkdir], [
+		#include <linux/fs.h>
+
+		int mkdir(struct inode *inode, struct dentry *dentry,
+		    umode_t umode) { return 0; }
+
+		static const struct inode_operations
+		    iops __attribute__ ((unused)) = {
+			.mkdir = 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 #
+	AC_MSG_CHECKING([whether iops->mkdir() takes struct user_namespace*])
+	ZFS_LINUX_TEST_RESULT([mkdir_user_namespace], [
+		AC_MSG_RESULT(yes)
+		AC_DEFINE(HAVE_IOPS_MKDIR_USERNS, 1,
+		    [iops->mkdir() takes struct user_namespace*])
+	],[
+		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
new file mode 100644
index 00000000000..ffe45106003
--- /dev/null
+++ b/config/kernel-mknod.m4
@@ -0,0 +1,30 @@
+AC_DEFUN([ZFS_AC_KERNEL_SRC_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.
+	dnl #
+	ZFS_LINUX_TEST_SRC([mknod_userns], [
+		#include <linux/fs.h>
+		#include <linux/sched.h>
+
+		int tmp_mknod(struct user_namespace *userns,
+		    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,
+		};
+	],[])
+])
+
+AC_DEFUN([ZFS_AC_KERNEL_MKNOD], [
+	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 f707391539d..31d199f33bb 100644
--- a/config/kernel-rename.m4
+++ b/config/kernel-rename.m4
@@ -1,10 +1,10 @@
-dnl #
-dnl # 4.9 API change,
-dnl # iops->rename2() merged into iops->rename(), and iops->rename() now wants
-dnl # flags.
-dnl #
-AC_DEFUN([ZFS_AC_KERNEL_SRC_RENAME_WANTS_FLAGS], [
-	ZFS_LINUX_TEST_SRC([inode_operations_rename], [
+AC_DEFUN([ZFS_AC_KERNEL_SRC_RENAME], [
+	dnl #
+	dnl # 4.9 API change,
+	dnl # iops->rename2() merged into iops->rename(), and iops->rename() now wants
+	dnl # flags.
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_operations_rename_flags], [
 		#include <linux/fs.h>
 		int rename_fn(struct inode *sip, struct dentry *sdp,
 			struct inode *tip, struct dentry *tdp,
@@ -15,15 +15,41 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_RENAME_WANTS_FLAGS], [
 			.rename = rename_fn,
 		};
 	],[])
+
+	dnl #
+	dnl # 5.12 API change,
+	dnl #
+	dnl # Linux 5.12 introduced passing struct user_namespace* as the first argument
+	dnl # of the rename() and other inode_operations members.
+	dnl #
+	ZFS_LINUX_TEST_SRC([inode_operations_rename_userns], [
+		#include <linux/fs.h>
+		int rename_fn(struct user_namespace *user_ns, 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_WANTS_FLAGS], [
-	AC_MSG_CHECKING([whether iops->rename() wants flags])
-	ZFS_LINUX_TEST_RESULT([inode_operations_rename], [
+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_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)
+
+		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)
+		])
 	])
 ])
diff --git a/config/kernel-setattr-prepare.m4 b/config/kernel-setattr-prepare.m4
index 45408c45c69..24245aa5344 100644
--- a/config/kernel-setattr-prepare.m4
+++ b/config/kernel-setattr-prepare.m4
@@ -1,27 +1,52 @@
-dnl #
-dnl # 4.9 API change
-dnl # The inode_change_ok() function has been renamed setattr_prepare()
-dnl # and updated to take a dentry rather than an inode.
-dnl #
 AC_DEFUN([ZFS_AC_KERNEL_SRC_SETATTR_PREPARE], [
+	dnl #
+	dnl # 4.9 API change
+	dnl # The inode_change_ok() function has been renamed setattr_prepare()
+	dnl # and updated to take a dentry rather than an inode.
+	dnl #
 	ZFS_LINUX_TEST_SRC([setattr_prepare], [
 		#include <linux/fs.h>
 	], [
 		struct dentry *dentry = NULL;
 		struct iattr *attr = NULL;
 		int error __attribute__ ((unused)) =
-		    setattr_prepare(dentry, attr);
+			setattr_prepare(dentry, attr);
+	])
+
+	dnl #
+	dnl # 5.12 API change
+	dnl # The setattr_prepare() function has been changed to accept a new argument
+	dnl # for struct user_namespace*
+	dnl #
+	ZFS_LINUX_TEST_SRC([setattr_prepare_userns], [
+		#include <linux/fs.h>
+	], [
+		struct dentry *dentry = NULL;
+		struct iattr *attr = NULL;
+		struct user_namespace *userns = NULL;
+		int error __attribute__ ((unused)) =
+			setattr_prepare(userns, dentry, attr);
 	])
 ])
 
 AC_DEFUN([ZFS_AC_KERNEL_SETATTR_PREPARE], [
-	AC_MSG_CHECKING([whether setattr_prepare() is available])
-	ZFS_LINUX_TEST_RESULT_SYMBOL([setattr_prepare],
+	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, 1,
-		    [setattr_prepare() is available])
+		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
new file mode 100644
index 00000000000..d90366d04b7
--- /dev/null
+++ b/config/kernel-symlink.m4
@@ -0,0 +1,30 @@
+AC_DEFUN([ZFS_AC_KERNEL_SRC_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.
+	dnl #
+	ZFS_LINUX_TEST_SRC([symlink_userns], [
+		#include <linux/fs.h>
+		#include <linux/sched.h>
+
+		int tmp_symlink(struct user_namespace *userns,
+		    struct inode *inode ,struct dentry *dentry,
+		    const char *path) { return 0; }
+
+		static const struct inode_operations
+			iops __attribute__ ((unused)) = {
+			.symlink		= tmp_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_RESULT(yes)
+		AC_DEFINE(HAVE_IOPS_SYMLINK_USERNS, 1,
+		    [iops->symlink() takes struct user_namespace*])
+	],[
+		AC_MSG_RESULT(no)
+	])
+])
diff --git a/config/kernel-xattr-handler.m4 b/config/kernel-xattr-handler.m4
index 137bf4a8aff..00b1e74a9cc 100644
--- a/config/kernel-xattr-handler.m4
+++ b/config/kernel-xattr-handler.m4
@@ -152,6 +152,21 @@ 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_userns], [
+		#include <linux/xattr.h>
+
+		int set(const struct xattr_handler *handler,
+			struct user_namespace *mnt_userns,
+			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_dentry_inode], [
 		#include <linux/xattr.h>
 
@@ -194,45 +209,58 @@ AC_DEFUN([ZFS_AC_KERNEL_SRC_XATTR_HANDLER_SET], [
 
 AC_DEFUN([ZFS_AC_KERNEL_XATTR_HANDLER_SET], [
 	dnl #
-	dnl # 4.7 API change,
-	dnl # The xattr_handler->set() callback was changed to take both
-	dnl # dentry and inode.
+	dnl # 5.12 API change,
+	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 and inode])
-	ZFS_LINUX_TEST_RESULT([xattr_handler_set_dentry_inode], [
+	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 55620b3daa8..b8d53490a4a 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -79,9 +79,9 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_EVICT_INODE
 	ZFS_AC_KERNEL_SRC_DIRTY_INODE
 	ZFS_AC_KERNEL_SRC_SHRINKER
-	ZFS_AC_KERNEL_SRC_MKDIR_UMODE_T
+	ZFS_AC_KERNEL_SRC_MKDIR
 	ZFS_AC_KERNEL_SRC_LOOKUP_FLAGS
-	ZFS_AC_KERNEL_SRC_CREATE_FLAGS
+	ZFS_AC_KERNEL_SRC_CREATE
 	ZFS_AC_KERNEL_SRC_GET_LINK
 	ZFS_AC_KERNEL_SRC_PUT_LINK
 	ZFS_AC_KERNEL_SRC_TMPFILE
@@ -115,7 +115,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_KUIDGID_T
 	ZFS_AC_KERNEL_SRC_KUID_HELPERS
 	ZFS_AC_KERNEL_SRC_MODULE_PARAM_CALL_CONST
-	ZFS_AC_KERNEL_SRC_RENAME_WANTS_FLAGS
+	ZFS_AC_KERNEL_SRC_RENAME
 	ZFS_AC_KERNEL_SRC_CURRENT_TIME
 	ZFS_AC_KERNEL_SRC_USERNS_CAPABILITIES
 	ZFS_AC_KERNEL_SRC_IN_COMPAT_SYSCALL
@@ -124,6 +124,10 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_SRC], [
 	ZFS_AC_KERNEL_SRC_TOTALHIGH_PAGES
 	ZFS_AC_KERNEL_SRC_KSTRTOUL
 	ZFS_AC_KERNEL_SRC_PERCPU
+	ZFS_AC_KERNEL_SRC_GENERIC_FILLATTR_USERNS
+	ZFS_AC_KERNEL_SRC_MKNOD
+	ZFS_AC_KERNEL_SRC_SYMLINK
+	ZFS_AC_KERNEL_SRC_BIO_MAX_SEGS
 
 	AC_MSG_CHECKING([for available kernel interfaces])
 	ZFS_LINUX_TEST_COMPILE_ALL([kabi])
@@ -176,9 +180,9 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_EVICT_INODE
 	ZFS_AC_KERNEL_DIRTY_INODE
 	ZFS_AC_KERNEL_SHRINKER
-	ZFS_AC_KERNEL_MKDIR_UMODE_T
+	ZFS_AC_KERNEL_MKDIR
 	ZFS_AC_KERNEL_LOOKUP_FLAGS
-	ZFS_AC_KERNEL_CREATE_FLAGS
+	ZFS_AC_KERNEL_CREATE
 	ZFS_AC_KERNEL_GET_LINK
 	ZFS_AC_KERNEL_PUT_LINK
 	ZFS_AC_KERNEL_TMPFILE
@@ -212,7 +216,7 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_KUIDGID_T
 	ZFS_AC_KERNEL_KUID_HELPERS
 	ZFS_AC_KERNEL_MODULE_PARAM_CALL_CONST
-	ZFS_AC_KERNEL_RENAME_WANTS_FLAGS
+	ZFS_AC_KERNEL_RENAME
 	ZFS_AC_KERNEL_CURRENT_TIME
 	ZFS_AC_KERNEL_USERNS_CAPABILITIES
 	ZFS_AC_KERNEL_IN_COMPAT_SYSCALL
@@ -221,6 +225,10 @@ AC_DEFUN([ZFS_AC_KERNEL_TEST_RESULT], [
 	ZFS_AC_KERNEL_TOTALHIGH_PAGES
 	ZFS_AC_KERNEL_KSTRTOUL
 	ZFS_AC_KERNEL_PERCPU
+	ZFS_AC_KERNEL_GENERIC_FILLATTR_USERNS
+	ZFS_AC_KERNEL_MKNOD
+	ZFS_AC_KERNEL_SYMLINK
+	ZFS_AC_KERNEL_BIO_MAX_SEGS
 ])
 
 dnl #
diff --git a/include/os/linux/kernel/linux/vfs_compat.h b/include/os/linux/kernel/linux/vfs_compat.h
index c35e80d31cd..91e908598fb 100644
--- a/include/os/linux/kernel/linux/vfs_compat.h
+++ b/include/os/linux/kernel/linux/vfs_compat.h
@@ -343,7 +343,8 @@ static inline void zfs_gid_write(struct inode *ip, gid_t gid)
 /*
  * 4.9 API change
  */
-#ifndef HAVE_SETATTR_PREPARE
+#if !(defined(HAVE_SETATTR_PREPARE_NO_USERNS) || \
+    defined(HAVE_SETATTR_PREPARE_USERNS))
 static inline int
 setattr_prepare(struct dentry *dentry, struct iattr *ia)
 {
@@ -389,6 +390,15 @@ func(const struct path *path, struct kstat *stat, u32 request_mask,	\
 {									\
 	return (func##_impl(path, stat, request_mask, query_flags));	\
 }
+#elif defined(HAVE_USERNS_IOPS_GETATTR)
+#define	ZPL_GETATTR_WRAPPER(func)					\
+static int								\
+func(struct user_namespace *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
@@ -436,4 +446,16 @@ zpl_is_32bit_api(void)
 #endif
 }
 
+/*
+ * 5.12 API change
+ * To support id-mapped mounts, generic_fillattr() was modified to
+ * accept a new struct user_namespace* as its first arg.
+ */
+#ifdef HAVE_GENERIC_FILLATTR_USERNS
+#define	zpl_generic_fillattr(user_ns, ip, sp)	\
+    generic_fillattr(user_ns, ip, sp)
+#else
+#define	zpl_generic_fillattr(user_ns, ip, sp)	generic_fillattr(ip, sp)
+#endif
+
 #endif /* _ZFS_VFS_H */
diff --git a/include/os/linux/kernel/linux/xattr_compat.h b/include/os/linux/kernel/linux/xattr_compat.h
index 8348e99198a..54690727eab 100644
--- a/include/os/linux/kernel/linux/xattr_compat.h
+++ b/include/os/linux/kernel/linux/xattr_compat.h
@@ -119,12 +119,27 @@ fn(struct dentry *dentry, const char *name, void *buffer, size_t size,	\
 #error "Unsupported kernel"
 #endif
 
+/*
+ * 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)
+#define	ZPL_XATTR_SET_WRAPPER(fn)					\
+static int								\
+fn(const struct xattr_handler *handler, struct user_namespace *user_ns, \
+    struct dentry *dentry, struct inode *inode, const char *name,	\
+    const void *buffer, size_t size, int flags)	\
+{									\
+	return (__ ## fn(inode, name, buffer, size, flags));		\
+}
 /*
  * 4.7 API change,
  * The xattr_handler->set() callback was changed to take a both dentry and
  * inode, because the dentry might not be attached to an inode yet.
  */
-#if defined(HAVE_XATTR_SET_DENTRY_INODE)
+#elif defined(HAVE_XATTR_SET_DENTRY_INODE)
 #define	ZPL_XATTR_SET_WRAPPER(fn)					\
 static int								\
 fn(const struct xattr_handler *handler, struct dentry *dentry,		\
diff --git a/include/os/linux/zfs/sys/zfs_vnops_os.h b/include/os/linux/zfs/sys/zfs_vnops_os.h
index 1c9cdf7bf8f..ba83f5dd83d 100644
--- a/include/os/linux/zfs/sys/zfs_vnops_os.h
+++ b/include/os/linux/zfs/sys/zfs_vnops_os.h
@@ -56,7 +56,8 @@ extern int zfs_mkdir(znode_t *dzp, char *dirname, vattr_t *vap,
 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 inode *ip, struct kstat *sp);
+extern int zfs_getattr_fast(struct user_namespace *, struct inode *ip,
+	struct kstat *sp);
 extern int zfs_setattr(znode_t *zp, vattr_t *vap, int flag, cred_t *cr);
 extern int zfs_rename(znode_t *sdzp, char *snm, znode_t *tdzp,
     char *tnm, cred_t *cr, int flags);
diff --git a/include/os/linux/zfs/sys/zpl.h b/include/os/linux/zfs/sys/zpl.h
index b0bb9c29c0b..21825d1f378 100644
--- a/include/os/linux/zfs/sys/zpl.h
+++ b/include/os/linux/zfs/sys/zpl.h
@@ -171,4 +171,22 @@ zpl_dir_emit_dots(struct file *file, zpl_dir_context_t *ctx)
 	timespec_trunc(ts, (ip)->i_sb->s_time_gran)
 #endif
 
+#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)
+#define	zpl_inode_owner_or_capable(ns, ip)	inode_owner_or_capable(ns, ip)
+#else
+#error "Unsupported kernel"
+#endif
+
+#ifdef HAVE_SETATTR_PREPARE_USERNS
+#define	zpl_setattr_prepare(ns, dentry, ia)	setattr_prepare(ns, dentry, ia)
+#else
+/*
+ * Use kernel-provided version, or our own from
+ * linux/vfs_compat.h
+ */
+#define	zpl_setattr_prepare(ns, dentry, ia)	setattr_prepare(dentry, ia)
+#endif
+
 #endif	/* _SYS_ZPL_H */
diff --git a/module/os/linux/zfs/policy.c b/module/os/linux/zfs/policy.c
index 8780d7f6c70..bbccb2e572d 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 (crgetfsuid(cr) == owner)
 		return (0);
 
-	if (inode_owner_or_capable(ip))
+	if (zpl_inode_owner_or_capable(kcred->user_ns, ip))
 		return (0);
 
 #if defined(CONFIG_USER_NS)
diff --git a/module/os/linux/zfs/vdev_disk.c b/module/os/linux/zfs/vdev_disk.c
index 08c33313407..aaaf4105979 100644
--- a/module/os/linux/zfs/vdev_disk.c
+++ b/module/os/linux/zfs/vdev_disk.c
@@ -593,9 +593,14 @@ __vdev_disk_physio(struct block_device *bdev, zio_t *zio,
 		}
 
 		/* bio_alloc() with __GFP_WAIT never returns NULL */
+#ifdef HAVE_BIO_MAX_SEGS
+		dr->dr_bio[i] = bio_alloc(GFP_NOIO, bio_max_segs(
+		    abd_nr_pages_off(zio->io_abd, bio_size, abd_offset)));
+#else
 		dr->dr_bio[i] = bio_alloc(GFP_NOIO,
 		    MIN(abd_nr_pages_off(zio->io_abd, bio_size, abd_offset),
 		    BIO_MAX_PAGES));
+#endif
 		if (unlikely(dr->dr_bio[i] == NULL)) {
 			vdev_disk_dio_free(dr);
 			return (SET_ERROR(ENOMEM));
diff --git a/module/os/linux/zfs/zfs_vnops_os.c b/module/os/linux/zfs/zfs_vnops_os.c
index 7484d651c1f..ce0701763fd 100644
--- a/module/os/linux/zfs/zfs_vnops_os.c
+++ b/module/os/linux/zfs/zfs_vnops_os.c
@@ -1907,7 +1907,8 @@ zfs_readdir(struct inode *ip, zpl_dir_context_t *ctx, cred_t *cr)
  */
 /* ARGSUSED */
 int
-zfs_getattr_fast(struct inode *ip, struct kstat *sp)
+zfs_getattr_fast(struct user_namespace *user_ns, struct inode *ip,
+    struct kstat *sp)
 {
 	znode_t *zp = ITOZ(ip);
 	zfsvfs_t *zfsvfs = ITOZSB(ip);
@@ -1919,7 +1920,7 @@ zfs_getattr_fast(struct inode *ip, struct kstat *sp)
 
 	mutex_enter(&zp->z_lock);
 
-	generic_fillattr(ip, sp);
+	zpl_generic_fillattr(user_ns, ip, sp);
 	/*
 	 * +1 link count for root inode with visible '.zfs' directory.
 	 */
diff --git a/module/os/linux/zfs/zpl_ctldir.c b/module/os/linux/zfs/zpl_ctldir.c
index e6420f19ed8..9b526afd000 100644
--- a/module/os/linux/zfs/zpl_ctldir.c
+++ b/module/os/linux/zfs/zpl_ctldir.c
@@ -101,12 +101,22 @@ zpl_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
  */
 /* ARGSUSED */
 static int
+#ifdef 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)
+#else
 zpl_root_getattr_impl(const struct path *path, struct kstat *stat,
     u32 request_mask, unsigned int query_flags)
+#endif
 {
 	struct inode *ip = path->dentry->d_inode;
 
+#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
+	generic_fillattr(user_ns, ip, stat);
+#else
 	generic_fillattr(ip, stat);
+#endif
 	stat->atime = current_time(ip);
 
 	return (0);
@@ -290,8 +300,14 @@ zpl_snapdir_readdir(struct file *filp, void *dirent, filldir_t filldir)
 #endif /* !HAVE_VFS_ITERATE && !HAVE_VFS_ITERATE_SHARED */
 
 static int
+#ifdef HAVE_IOPS_RENAME_USERNS
+zpl_snapdir_rename2(struct user_namespace *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)
+#endif
 {
 	cred_t *cr = CRED();
 	int error;
@@ -309,7 +325,7 @@ zpl_snapdir_rename2(struct inode *sdip, struct dentry *sdentry,
 	return (error);
 }
 
-#ifndef HAVE_RENAME_WANTS_FLAGS
+#if !defined(HAVE_RENAME_WANTS_FLAGS) && !defined(HAVE_IOPS_RENAME_USERNS)
 static int
 zpl_snapdir_rename(struct inode *sdip, struct dentry *sdentry,
     struct inode *tdip, struct dentry *tdentry)
@@ -333,7 +349,12 @@ zpl_snapdir_rmdir(struct inode *dip, struct dentry *dentry)
 }
 
 static int
+#ifdef HAVE_IOPS_MKDIR_USERNS
+zpl_snapdir_mkdir(struct user_namespace *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
 {
 	cred_t *cr = CRED();
 	vattr_t *vap;
@@ -363,14 +384,24 @@ zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, umode_t mode)
  */
 /* ARGSUSED */
 static int
+#ifdef 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)
+#else
 zpl_snapdir_getattr_impl(const struct path *path, struct kstat *stat,
     u32 request_mask, unsigned int query_flags)
+#endif
 {
 	struct inode *ip = path->dentry->d_inode;
 	zfsvfs_t *zfsvfs = ITOZSB(ip);
 
 	ZPL_ENTER(zfsvfs);
+#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
+	generic_fillattr(user_ns, ip, stat);
+#else
 	generic_fillattr(ip, stat);
+#endif
 
 	stat->nlink = stat->size = 2;
 	stat->ctime = stat->mtime = dmu_objset_snap_cmtime(zfsvfs->z_os);
@@ -408,7 +439,7 @@ const struct file_operations zpl_fops_snapdir = {
 const struct inode_operations zpl_ops_snapdir = {
 	.lookup		= zpl_snapdir_lookup,
 	.getattr	= zpl_snapdir_getattr,
-#ifdef HAVE_RENAME_WANTS_FLAGS
+#if defined(HAVE_RENAME_WANTS_FLAGS) || defined(HAVE_IOPS_RENAME_USERNS)
 	.rename		= zpl_snapdir_rename2,
 #else
 	.rename		= zpl_snapdir_rename,
@@ -495,8 +526,14 @@ zpl_shares_readdir(struct file *filp, void *dirent, filldir_t filldir)
 
 /* ARGSUSED */
 static int
+#ifdef HAVE_USERNS_IOPS_GETATTR
+zpl_shares_getattr_impl(struct user_namespace *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)
+#endif
 {
 	struct inode *ip = path->dentry->d_inode;
 	zfsvfs_t *zfsvfs = ITOZSB(ip);
@@ -506,7 +543,11 @@ 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)
+		generic_fillattr(user_ns, path->dentry->d_inode, stat);
+#else
 		generic_fillattr(path->dentry->d_inode, stat);
+#endif
 		stat->nlink = stat->size = 2;
 		stat->atime = current_time(ip);
 		ZPL_EXIT(zfsvfs);
@@ -515,7 +556,11 @@ zpl_shares_getattr_impl(const struct path *path, struct kstat *stat,
 
 	error = -zfs_zget(zfsvfs, zfsvfs->z_shares_dir, &dzp);
 	if (error == 0) {
-		error = -zfs_getattr_fast(ZTOI(dzp), stat);
+#if defined(HAVE_GENERIC_FILLATTR_USERNS) && defined(HAVE_USERNS_IOPS_GETATTR)
+		error = -zfs_getattr_fast(user_ns, ZTOI(dzp), stat);
+#else
+		error = -zfs_getattr_fast(kcred->user_ns, ZTOI(dzp), stat);
+#endif
 		iput(ZTOI(dzp));
 	}
 
diff --git a/module/os/linux/zfs/zpl_file.c b/module/os/linux/zfs/zpl_file.c
index 80762f9669b..08bf97ff338 100644
--- a/module/os/linux/zfs/zpl_file.c
+++ b/module/os/linux/zfs/zpl_file.c
@@ -869,7 +869,7 @@ __zpl_ioctl_setflags(struct inode *ip, uint32_t ioctl_flags, xvattr_t *xva)
 	    !capable(CAP_LINUX_IMMUTABLE))
 		return (-EACCES);
 
-	if (!inode_owner_or_capable(ip))
+	if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
 		return (-EACCES);
 
 	xva_init(xva);
diff --git a/module/os/linux/zfs/zpl_inode.c b/module/os/linux/zfs/zpl_inode.c
index f336fbb1272..364b9fbef24 100644
--- a/module/os/linux/zfs/zpl_inode.c
+++ b/module/os/linux/zfs/zpl_inode.c
@@ -128,7 +128,12 @@ zpl_vap_init(vattr_t *vap, struct inode *dir, umode_t mode, cred_t *cr)
 }
 
 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)
+#else
 zpl_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool flag)
+#endif
 {
 	cred_t *cr = CRED();
 	znode_t *zp;
@@ -163,7 +168,12 @@ zpl_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool flag)
 }
 
 static int
+#ifdef HAVE_IOPS_MKNOD_USERNS
+zpl_mknod(struct user_namespace *user_ns, struct inode *dir,
+    struct dentry *dentry, umode_t mode,
+#else
 zpl_mknod(struct inode *dir, struct dentry *dentry, umode_t mode,
+#endif
     dev_t rdev)
 {
 	cred_t *cr = CRED();
@@ -278,7 +288,12 @@ zpl_unlink(struct inode *dir, struct dentry *dentry)
 }
 
 static int
+#ifdef HAVE_IOPS_MKDIR_USERNS
+zpl_mkdir(struct user_namespace *user_ns, struct inode *dir,
+    struct dentry *dentry, umode_t mode)
+#else
 zpl_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
+#endif
 {
 	cred_t *cr = CRED();
 	vattr_t *vap;
@@ -338,8 +353,14 @@ zpl_rmdir(struct inode *dir, struct dentry *dentry)
 }
 
 static int
+#ifdef HAVE_USERNS_IOPS_GETATTR
+zpl_getattr_impl(struct user_namespace *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)
+#endif
 {
 	int error;
 	fstrans_cookie_t cookie;
@@ -350,7 +371,11 @@ zpl_getattr_impl(const struct path *path, struct kstat *stat, u32 request_mask,
 	 * XXX request_mask and query_flags currently ignored.
 	 */
 
-	error = -zfs_getattr_fast(path->dentry->d_inode, stat);
+#ifdef HAVE_USERNS_IOPS_GETATTR
+	error = -zfs_getattr_fast(user_ns, path->dentry->d_inode, stat);
+#else
+	error = -zfs_getattr_fast(kcred->user_ns, path->dentry->d_inode, stat);
+#endif
 	spl_fstrans_unmark(cookie);
 	ASSERT3S(error, <=, 0);
 
@@ -359,7 +384,12 @@ 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
+zpl_setattr(struct user_namespace *user_ns, struct dentry *dentry,
+    struct iattr *ia)
+#else
 zpl_setattr(struct dentry *dentry, struct iattr *ia)
+#endif
 {
 	struct inode *ip = dentry->d_inode;
 	cred_t *cr = CRED();
@@ -367,7 +397,7 @@ zpl_setattr(struct dentry *dentry, struct iattr *ia)
 	int error;
 	fstrans_cookie_t cookie;
 
-	error = setattr_prepare(dentry, ia);
+	error = zpl_setattr_prepare(kcred->user_ns, dentry, ia);
 	if (error)
 		return (error);
 
@@ -399,8 +429,14 @@ zpl_setattr(struct dentry *dentry, struct iattr *ia)
 }
 
 static int
+#ifdef HAVE_IOPS_RENAME_USERNS
+zpl_rename2(struct user_namespace *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)
+#endif
 {
 	cred_t *cr = CRED();
 	int error;
@@ -421,7 +457,7 @@ zpl_rename2(struct inode *sdip, struct dentry *sdentry,
 	return (error);
 }
 
-#ifndef HAVE_RENAME_WANTS_FLAGS
+#if !defined(HAVE_RENAME_WANTS_FLAGS) && !defined(HAVE_IOPS_RENAME_USERNS)
 static int
 zpl_rename(struct inode *sdip, struct dentry *sdentry,
     struct inode *tdip, struct dentry *tdentry)
@@ -431,7 +467,12 @@ zpl_rename(struct inode *sdip, struct dentry *sdentry,
 #endif
 
 static int
+#ifdef HAVE_IOPS_SYMLINK_USERNS
+zpl_symlink(struct user_namespace *user_ns, struct inode *dir,
+    struct dentry *dentry, const char *name)
+#else
 zpl_symlink(struct inode *dir, struct dentry *dentry, const char *name)
+#endif
 {
 	cred_t *cr = CRED();
 	vattr_t *vap;
@@ -677,7 +718,7 @@ const struct inode_operations zpl_dir_inode_operations = {
 	.mkdir		= zpl_mkdir,
 	.rmdir		= zpl_rmdir,
 	.mknod		= zpl_mknod,
-#ifdef HAVE_RENAME_WANTS_FLAGS
+#if defined(HAVE_RENAME_WANTS_FLAGS) || defined(HAVE_IOPS_RENAME_USERNS)
 	.rename		= zpl_rename2,
 #else
 	.rename		= zpl_rename,
diff --git a/module/os/linux/zfs/zpl_xattr.c b/module/os/linux/zfs/zpl_xattr.c
index 1ec3dae2bb8..5e35f90df85 100644
--- a/module/os/linux/zfs/zpl_xattr.c
+++ b/module/os/linux/zfs/zpl_xattr.c
@@ -1233,7 +1233,7 @@ __zpl_xattr_acl_set_access(struct inode *ip, const char *name,
 	if (ITOZSB(ip)->z_acl_type != ZFS_ACLTYPE_POSIX)
 		return (-EOPNOTSUPP);
 
-	if (!inode_owner_or_capable(ip))
+	if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
 		return (-EPERM);
 
 	if (value) {
@@ -1273,7 +1273,7 @@ __zpl_xattr_acl_set_default(struct inode *ip, const char *name,
 	if (ITOZSB(ip)->z_acl_type != ZFS_ACLTYPE_POSIX)
 		return (-EOPNOTSUPP);
 
-	if (!inode_owner_or_capable(ip))
+	if (!zpl_inode_owner_or_capable(kcred->user_ns, ip))
 		return (-EPERM);
 
 	if (value) {