zfs list: Allow more fields in ZFS_ITER_SIMPLE mode

If the fields to be listed and sorted by are constrained to those
populated by dsl_dataset_fast_stat(), then zfs list is much faster,
as it does not need to open each objset and reads its properties.

A previous optimization by Pawel Dawidek
(0cee24064a79f9c01fc4521543c37acea538405f) took advantage
of this to make listing snapshot names sorted only by name much faster.

However, it was limited to `-o name -s name`, this work extends this
optimization to work with:
  - name
  - guid
  - createtxg
  - numclones
  - inconsistent
  - redacted
  - origin
and could be further extended to any other properties supported by
dsl_dataset_fast_stat() or similar, that do not require extra locking
or reading from disk.

This was committed before (9a9e2e343dfa2af28bf7910de77ae73aa006de62),
but was reverted due to a regression when used with an older kernel.

If the kernel does not populate zc->zc_objset_stats, we now fallback
to getting the properties via the slower interface, to avoid problems
with newer userland and older kernels.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Allan Jude <[email protected]>
Closes #14110

1 files changed, 15 insertions, 7 deletions

diff --git a/include/libzfs.h b/include/libzfs.h
index 2806d1f7c..e56374922 100644
--- a/include/libzfs.h
+++ b/include/libzfs.h
@@ -646,19 +646,27 @@ _LIBZFS_H void zprop_print_one_property(const char *, zprop_get_cbdata_t *,
 /*
  * Iterator functions.
  */
+#define	ZFS_ITER_RECURSE		(1 << 0)
+#define	ZFS_ITER_ARGS_CAN_BE_PATHS	(1 << 1)
+#define	ZFS_ITER_PROP_LISTSNAPS		(1 << 2)
+#define	ZFS_ITER_DEPTH_LIMIT		(1 << 3)
+#define	ZFS_ITER_RECVD_PROPS		(1 << 4)
+#define	ZFS_ITER_LITERAL_PROPS		(1 << 5)
+#define	ZFS_ITER_SIMPLE			(1 << 6)
+
 typedef int (*zfs_iter_f)(zfs_handle_t *, void *);
 _LIBZFS_H int zfs_iter_root(libzfs_handle_t *, zfs_iter_f, void *);
-_LIBZFS_H int zfs_iter_children(zfs_handle_t *, zfs_iter_f, void *);
-_LIBZFS_H int zfs_iter_dependents(zfs_handle_t *, boolean_t, zfs_iter_f,
+_LIBZFS_H int zfs_iter_children(zfs_handle_t *, int, zfs_iter_f, void *);
+_LIBZFS_H int zfs_iter_dependents(zfs_handle_t *, int, boolean_t, zfs_iter_f,
     void *);
-_LIBZFS_H int zfs_iter_filesystems(zfs_handle_t *, zfs_iter_f, void *);
-_LIBZFS_H int zfs_iter_snapshots(zfs_handle_t *, boolean_t, zfs_iter_f, void *,
+_LIBZFS_H int zfs_iter_filesystems(zfs_handle_t *, int, zfs_iter_f, void *);
+_LIBZFS_H int zfs_iter_snapshots(zfs_handle_t *, int, zfs_iter_f, void *,
     uint64_t, uint64_t);
-_LIBZFS_H int zfs_iter_snapshots_sorted(zfs_handle_t *, zfs_iter_f, void *,
+_LIBZFS_H int zfs_iter_snapshots_sorted(zfs_handle_t *, int, zfs_iter_f, void *,
     uint64_t, uint64_t);
-_LIBZFS_H int zfs_iter_snapspec(zfs_handle_t *, const char *, zfs_iter_f,
+_LIBZFS_H int zfs_iter_snapspec(zfs_handle_t *, int, const char *, zfs_iter_f,
     void *);
-_LIBZFS_H int zfs_iter_bookmarks(zfs_handle_t *, zfs_iter_f, void *);
+_LIBZFS_H int zfs_iter_bookmarks(zfs_handle_t *, int, zfs_iter_f, void *);
 _LIBZFS_H int zfs_iter_mounted(zfs_handle_t *, zfs_iter_f, void *);
 
 typedef struct get_all_cb {