Implement bookmark copying

This feature allows copying existing bookmarks using

    zfs bookmark fs#target fs#newbookmark

There are some niche use cases for such functionality,
e.g. when using bookmarks as markers for replication progress.

Copying redaction bookmarks produces a normal bookmark that
cannot be used for redacted send (we are not duplicating
the redaction object).

ZCP support for bookmarking (both creation and copying) will be
implemented in a separate patch based on this work.

Overview:

- Terminology:
    - source = existing snapshot or bookmark
    - new/bmark = new bookmark
- Implement bookmark copying in `dsl_bookmark.c`
  - create new bookmark node
  - copy source's `zbn_phys` to new's `zbn_phys`
  - zero-out redaction object id in copy
- Extend existing bookmark ioctl nvlist schema to accept
  bookmarks as sources
  - => `dsl_bookmark_create_nvl_validate` is authoritative
- use `dsl_dataset_is_before` check for both snapshot
  and bookmark sources
- Adjust CLI
  - refactor shortname expansion logic in `zfs_do_bookmark`
- Update man pages
  - warn about redaction bookmark handling
- Add test cases
  - CLI
  - pyyzfs libzfs_core bindings

Reviewed-by: Matt Ahrens <[email protected]>
Reviewed-by: Paul Dagnelie <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by: Christian Schwarz <[email protected]>
Closes #9571

1 files changed, 7 insertions, 23 deletions

diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index b2517d84f..7ef54a098 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -37,6 +37,7 @@
  * Copyright 2017 RackTop Systems.
  * Copyright (c) 2017 Open-E, Inc. All Rights Reserved.
  * Copyright (c) 2019 Datto Inc.
+ * Copyright (c) 2019, 2020 by Christian Schwarz. All rights reserved.
  */
 
 /*
@@ -3614,11 +3615,13 @@ zfs_ioc_destroy_snaps(const char *poolname, nvlist_t *innvl, nvlist_t *outnvl)
 }
 
 /*
- * Create bookmarks.  Bookmark names are of the form <fs>#<bmark>.
- * All bookmarks must be in the same pool.
+ * Create bookmarks. The bookmark names are of the form <fs>#<bmark>.
+ * All bookmarks and snapshots must be in the same pool.
+ * dsl_bookmark_create_nvl_validate describes the nvlist schema in more detail.
  *
  * innvl: {
- *     bookmark1 -> snapshot1, bookmark2 -> snapshot2
+ *     new_bookmark1 -> existing_snapshot,
+ *     new_bookmark2 -> existing_bookmark,
  * }
  *
  * outnvl: bookmark -> error code (int32)
@@ -3632,25 +3635,6 @@ static const zfs_ioc_key_t zfs_keys_bookmark[] = {
 static int
 zfs_ioc_bookmark(const char *poolname, nvlist_t *innvl, nvlist_t *outnvl)
 {
-	for (nvpair_t *pair = nvlist_next_nvpair(innvl, NULL);
-	    pair != NULL; pair = nvlist_next_nvpair(innvl, pair)) {
-		char *snap_name;
-
-		/*
-		 * Verify the snapshot argument.
-		 */
-		if (nvpair_value_string(pair, &snap_name) != 0)
-			return (SET_ERROR(EINVAL));
-
-
-		/* Verify that the keys (bookmarks) are unique */
-		for (nvpair_t *pair2 = nvlist_next_nvpair(innvl, pair);
-		    pair2 != NULL; pair2 = nvlist_next_nvpair(innvl, pair2)) {
-			if (strcmp(nvpair_name(pair), nvpair_name(pair2)) == 0)
-				return (SET_ERROR(EINVAL));
-		}
-	}
-
 	return (dsl_bookmark_create(innvl, outnvl));
 }
 
@@ -4164,7 +4148,7 @@ recursive_unmount(const char *fsname, void *arg)
  * snapname is the snapshot to redact.
  * innvl: {
  *     "bookname" -> (string)
- *         name of the redaction bookmark to generate
+ *         shortname of the redaction bookmark to generate
  *     "snapnv" -> (nvlist, values ignored)
  *         snapshots to redact snapname with respect to
  * }