Create zap for root vdev

And add it to the AVZ, this is not backwards compatible with older pools
due to an assertion in spa_sync() that verifies the number of ZAPs of
all vdevs matches the number of ZAPs in the AVZ.

Granted, the assertion only applies to #DEBUG builds - still, a feature
flag is introduced to avoid the assertion, com.klarasystems:vdev_zaps_v2

Notably, this allows to get/set properties on the root vdev:

    % zpool set user:prop=value <pool> root-0

Before this commit, it was already possible to get/set properties on
top-level vdevs with the syntax <type>-<vdev_id> (e.g. mirror-0):

    % zpool set user:prop=value <pool> mirror-0

This syntax also applies to the root vdev as it is is of type 'root'
with a vdev_id of 0, root-0. The keyword 'root' as an alias for
'root-0'.

The following tests have been added:

    - zpool get all properties from root vdev
    - zpool set a property on root vdev
    - verify root vdev ZAP is created

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Rob Wing <[email protected]>
Sponsored-by: Seagate Technology
Submitted-by: Klara, Inc.
Closes #14405

1 files changed, 1 insertions, 0 deletions

diff --git a/include/sys/fs/zfs.h b/include/sys/fs/zfs.h
index 25babd4ea..0734ff122 100644
--- a/include/sys/fs/zfs.h
+++ b/include/sys/fs/zfs.h
@@ -816,6 +816,7 @@ typedef struct zpool_load_policy {
 #define	ZPOOL_CONFIG_FEATURES_FOR_READ	"features_for_read"
 #define	ZPOOL_CONFIG_FEATURE_STATS	"feature_stats"	/* not stored on disk */
 #define	ZPOOL_CONFIG_ERRATA		"errata"	/* not stored on disk */
+#define	ZPOOL_CONFIG_VDEV_ROOT_ZAP	"com.klarasystems:vdev_zap_root"
 #define	ZPOOL_CONFIG_VDEV_TOP_ZAP	"com.delphix:vdev_zap_top"
 #define	ZPOOL_CONFIG_VDEV_LEAF_ZAP	"com.delphix:vdev_zap_leaf"
 #define	ZPOOL_CONFIG_HAS_PER_VDEV_ZAPS	"com.delphix:has_per_vdev_zaps"