Restore aclmode and remove acltype on FreeBSD

This replaces the placeholder ZFS_PROP_PRIVATE with ZFS_PROP_ACLMODE,
matching what is done in the NFSv4 ACLs PR (openzfs#9709).

On FreeBSD we hide ZFS_PROP_ACLTYPE, while on Linux we hide
ZFS_PROP_ACLMODE.

The tests already assume this arrangement.

Signed-off-by: Ryan Moeller <ryan@iXsystems.com>

include/sys/fs/zfs.h

@@ -115,7 +115,7 @@ typedef enum {
 	ZFS_PROP_READONLY,
 	ZFS_PROP_ZONED,
 	ZFS_PROP_SNAPDIR,
-	ZFS_PROP_PRIVATE,		/* not exposed to user, temporary */
+	ZFS_PROP_ACLMODE,
 	ZFS_PROP_ACLINHERIT,
 	ZFS_PROP_CREATETXG,
 	ZFS_PROP_NAME,			/* not exposed to the user */

man/man8/zfsprops.8

@@ -37,7 +37,7 @@
 .\" Copyright 2018 Nexenta Systems, Inc.
 .\" Copyright 2019 Joyent, Inc.
 .\"
-.Dd June 30, 2019
+.Dd January 30, 2020
 .Dt ZFSPROPS 8
 .Os Linux
 .Sh NAME
@@ -599,8 +599,58 @@ accordance to the requested mode from the application.
 The
 .Sy aclinherit
 property does not apply to POSIX ACLs.
+.It Sy aclmode Ns = Ns Sy discard Ns | Ns Sy groupmask Ns | Ns Sy passthrough
+.Ns Sy restricted
+Controls how an
+.Tn ACL
+is modified during
+.Xr chmod 2 .
+This property is not visible on Linux yet.
+.Bl -tag -width "passthrough"
+.It Sy discard
+default, deletes all
+.Tn ACL
+entries that do not represent the mode of the file.
+.It Sy groupmask
+reduces permissions granted in all
+.Em ALLOW
+entried found in the
+.Tn ACL
+such that they are no greater than the group permissions specified by
+.Xr chmod 2 .
+.It Sy passthrough
+indicates that no changes are made to the
+.Tn ACL
+other than creating or updating the necessary
+.Tn ACL
+entries to represent the new mode of the file or directory.
+.It Sy restricted
+will cause the
+.Xr chmod 2
+operation to return an error when used on any file or directory which has
+a non-trivial
+.Tn ACL
+whose entries can not be represented by a mode.
+.Xr chmod 2
+is required to change the set user ID, set group ID, or sticky bits on a file
+or directory, as they do not have equivalent
+.Tn ACL
+entries.
+In order to use
+.Xr chmod 2
+on a file or directory with a non-trivial
+.Tn ACL
+when
+.Sy aclmode
+is set to
+.Sy restricted ,
+you must first remove all
+.Tn ACL
+entries which do not represent the current mode.
+.El
 .It Sy acltype Ns = Ns Sy off Ns | Ns Sy noacl Ns | Ns Sy posixacl
 Controls whether ACLs are enabled and if so what type of ACL to use.
+This property is not visible on FreeBSD yet.
 .Bl -tag -width "posixacl"
 .It Sy off
 default, when a file system has the

module/zcommon/zfs_prop.c

@@ -160,6 +160,14 @@ zfs_prop_init(void)
 		{ NULL }
 	};
 
+	static zprop_index_t acl_mode_table[] = {
+		{ "discard",	ZFS_ACL_DISCARD },
+		{ "groupmask",	ZFS_ACL_GROUPMASK },
+		{ "passthrough", ZFS_ACL_PASSTHROUGH },
+		{ "restricted",	ZFS_ACL_RESTRICTED },
+		{ NULL }
+	};
+
 	static zprop_index_t acltype_table[] = {
 		{ "off",	ZFS_ACLTYPE_OFF },
 		{ "disabled",	ZFS_ACLTYPE_OFF },
@@ -330,9 +338,16 @@ zfs_prop_init(void)
 	zprop_register_index(ZFS_PROP_SNAPDEV, "snapdev", ZFS_SNAPDEV_HIDDEN,
 	    PROP_INHERIT, ZFS_TYPE_FILESYSTEM | ZFS_TYPE_VOLUME,
 	    "hidden | visible", "SNAPDEV", snapdev_table);
+#ifdef __FreeBSD__
+	zprop_register_index(ZFS_PROP_ACLMODE, "aclmode", ZFS_ACL_DISCARD,
+	    PROP_INHERIT, ZFS_TYPE_FILESYSTEM,
+	    "discard | groupmask | passthrough | restricted", "ACLMODE",
+	    acl_mode_table);
+#else
 	zprop_register_index(ZFS_PROP_ACLTYPE, "acltype", ZFS_ACLTYPE_OFF,
 	    PROP_INHERIT, ZFS_TYPE_FILESYSTEM | ZFS_TYPE_SNAPSHOT,
 	    "noacl | posixacl", "ACLTYPE", acltype_table);
+#endif
 	zprop_register_index(ZFS_PROP_ACLINHERIT, "aclinherit",
 	    ZFS_ACL_RESTRICTED, PROP_INHERIT, ZFS_TYPE_FILESYSTEM,
 	    "discard | noallow | restricted | passthrough | passthrough-x",
@@ -602,9 +617,17 @@ zfs_prop_init(void)
 	 * that we don't have to change the values of the zfs_prop_t enum, or
 	 * have NULL pointers in the zfs_prop_table[].
 	 */
-	zprop_register_hidden(ZFS_PROP_PRIVATE, "priv_prop",
-	    PROP_TYPE_NUMBER, PROP_READONLY, ZFS_TYPE_FILESYSTEM,
-	    "PRIV_PROP");
+#ifdef __FreeBSD__
+	zprop_register_impl(ZFS_PROP_ACLTYPE, "acltype", PROP_TYPE_INDEX,
+	    ZFS_ACLTYPE_OFF, NULL, PROP_INHERIT,
+	    ZFS_TYPE_FILESYSTEM | ZFS_TYPE_SNAPSHOT,
+	    "noacl | posixacl", "ACLTYPE", B_FALSE, B_FALSE, acltype_table);
+#else
+	zprop_register_impl(ZFS_PROP_ACLMODE, "aclmode", PROP_TYPE_INDEX,
+	    ZFS_ACL_DISCARD, NULL, PROP_INHERIT, ZFS_TYPE_FILESYSTEM,
+	    "discard | groupmask | passthrough | restricted", "ACLMODE",
+	    B_FALSE, B_FALSE, acl_mode_table);
+#endif
 	zprop_register_hidden(ZFS_PROP_REMAPTXG, "remaptxg", PROP_TYPE_NUMBER,
 	    PROP_READONLY, ZFS_TYPE_DATASET, "REMAPTXG");