Expose dataset encryption status via fast stat path

In truenas_pylibzfs, we query list of encrypted datasets several times,
which is expensive. This commit exposes a public API zfs_is_encrypted()
to get encryption status from fast stat path without having to refresh
the properties.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Rob Norris <robn@despairlabs.com>
Signed-off-by: Ameer Hamza <ahamza@ixsystems.com>
Closes #17368

include/libzfs.h

@@ -591,6 +591,7 @@ _LIBZFS_H int zfs_crypto_attempt_load_keys(libzfs_handle_t *, const char *);
 _LIBZFS_H int zfs_crypto_load_key(zfs_handle_t *, boolean_t, const char *);
 _LIBZFS_H int zfs_crypto_unload_key(zfs_handle_t *);
 _LIBZFS_H int zfs_crypto_rewrap(zfs_handle_t *, nvlist_t *, boolean_t);
+_LIBZFS_H boolean_t zfs_is_encrypted(zfs_handle_t *);
 
 typedef struct zprop_list {
 	int		pl_prop;

include/sys/dmu.h

@@ -997,6 +997,11 @@ void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
 
 void dmu_object_dnsize_from_db(dmu_buf_t *db, int *dnsize);
 
+typedef enum {
+	DDS_FLAG_ENCRYPTED = (1<<0),
+	DDS_FLAG_HAS_ENCRYPTED = (1<<7),
+} dmu_objset_flag_t;
+
 typedef struct dmu_objset_stats {
 	uint64_t dds_num_clones; /* number of clones of this */
 	uint64_t dds_creation_txg;
@@ -1006,6 +1011,7 @@ typedef struct dmu_objset_stats {
 	uint8_t dds_inconsistent;
 	uint8_t dds_redacted;
 	char dds_origin[ZFS_MAX_DATASET_NAME_LEN];
+	uint8_t dds_flags; /* dmu_objset_flag_t */
 } dmu_objset_stats_t;
 
 /*

lib/libzfs/libzfs.abi

@@ -345,6 +345,7 @@
     <elf-symbol name='zfs_hold' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_hold_nvl' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_ioctl' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='zfs_is_encrypted' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_is_mounted' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_is_shared' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='zfs_isnumber' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
@@ -1925,6 +1926,9 @@
       <data-member access='public' layout-offset-in-bits='248'>
         <var-decl name='dds_origin' type-id='d1617432' visibility='default'/>
       </data-member>
+      <data-member access='public' layout-offset-in-bits='2296'>
+        <var-decl name='dds_flags' type-id='b96825af' visibility='default'/>
+      </data-member>
     </class-decl>
     <typedef-decl name='dmu_objset_stats_t' type-id='098f0221' id='b2c14f17'/>
     <enum-decl name='zfs_type_t' naming-typedef-id='2e45de5d' id='5d8f7321'>
@@ -3805,6 +3809,10 @@
       <parameter type-id='c19b74c3' name='inheritkey'/>
       <return type-id='95e97e5e'/>
     </function-decl>
+    <function-decl name='zfs_is_encrypted' mangled-name='zfs_is_encrypted' visibility='default' binding='global' size-in-bits='64' elf-symbol-id='zfs_is_encrypted'>
+      <parameter type-id='9200a744' name='zhp'/>
+      <return type-id='c19b74c3'/>
+    </function-decl>
     <function-decl name='zfs_error_aux' visibility='default' binding='global' size-in-bits='64'>
       <parameter type-id='b0382bb3'/>
       <parameter type-id='80f4b756'/>

lib/libzfs/libzfs_crypto.c

@@ -1818,3 +1818,14 @@ error:
 	zfs_error(zhp->zfs_hdl, EZFS_CRYPTOFAILED, errbuf);
 	return (ret);
 }
+
+boolean_t
+zfs_is_encrypted(zfs_handle_t *zhp)
+{
+	uint8_t flags = zhp->zfs_dmustats.dds_flags;
+
+	if (flags & DDS_FLAG_HAS_ENCRYPTED)
+		return ((flags & DDS_FLAG_ENCRYPTED) != 0);
+
+	return (zfs_prop_get_int(zhp, ZFS_PROP_ENCRYPTION) != ZIO_CRYPT_OFF);
+}

lib/libzfs_core/libzfs_core.abi

@@ -1461,6 +1461,9 @@
       <data-member access='public' layout-offset-in-bits='248'>
         <var-decl name='dds_origin' type-id='d1617432' visibility='default'/>
       </data-member>
+      <data-member access='public' layout-offset-in-bits='2296'>
+        <var-decl name='dds_flags' type-id='b96825af' visibility='default'/>
+      </data-member>
     </class-decl>
     <typedef-decl name='dmu_objset_stats_t' type-id='098f0221' id='b2c14f17'/>
     <enum-decl name='dmu_objset_type' id='6b1b19f9'>

module/zfs/dsl_dataset.c

@@ -2886,6 +2886,9 @@ dsl_dataset_fast_stat(dsl_dataset_t *ds, dmu_objset_stats_t *stat)
 	stat->dds_guid = dsl_get_guid(ds);
 	stat->dds_redacted = dsl_get_redacted(ds);
 	stat->dds_origin[0] = '\0';
+	stat->dds_flags = DDS_FLAG_HAS_ENCRYPTED;
+	if (ds->ds_dir->dd_crypto_obj != 0)
+		stat->dds_flags |= DDS_FLAG_ENCRYPTED;
 	if (ds->ds_is_snapshot) {
 		stat->dds_is_snapshot = B_TRUE;
 		stat->dds_num_clones = dsl_get_numclones(ds);