Implement Redacted Send/Receive

Redacted send/receive allows users to send subsets of their data to 
a target system. One possible use case for this feature is to not 
transmit sensitive information to a data warehousing, test/dev, or 
analytics environment. Another is to save space by not replicating 
unimportant data within a given dataset, for example in backup tools 
like zrepl.

Redacted send/receive is a three-stage process. First, a clone (or 
clones) is made of the snapshot to be sent to the target. In this 
clone (or clones), all unnecessary or unwanted data is removed or
modified. This clone is then snapshotted to create the "redaction 
snapshot" (or snapshots). Second, the new zfs redact command is used 
to create a redaction bookmark. The redaction bookmark stores the 
list of blocks in a snapshot that were modified by the redaction 
snapshot(s). Finally, the redaction bookmark is passed as a parameter 
to zfs send. When sending to the snapshot that was redacted, the
redaction bookmark is used to filter out blocks that contain sensitive 
or unwanted information, and those blocks are not included in the send 
stream.  When sending from the redaction bookmark, the blocks it 
contains are considered as candidate blocks in addition to those 
blocks in the destination snapshot that were modified since the 
creation_txg of the redaction bookmark.  This step is necessary to 
allow the target to rehydrate data in the case where some blocks are 
accidentally or unnecessarily modified in the redaction snapshot.

The changes to bookmarks to enable fast space estimation involve 
adding deadlists to bookmarks. There is also logic to manage the 
life cycles of these deadlists.

The new size estimation process operates in cases where previously 
an accurate estimate could not be provided. In those cases, a send 
is performed where no data blocks are read, reducing the runtime 
significantly and providing a byte-accurate size estimate.

Reviewed-by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Prashanth Sreenivasa <pks@delphix.com>
Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: George Wilson <george.wilson@delphix.com>
Reviewed-by: Chris Williamson <chris.williamson@delphix.com>
Reviewed-by: Pavel Zhakarov <pavel.zakharov@delphix.com>
Reviewed-by: Sebastien Roy <sebastien.roy@delphix.com>
Reviewed-by: Prakash Surya <prakash.surya@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes #7958

include/libzfs_core.h

@@ -20,7 +20,7 @@
  */
 
 /*
- * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
+ * Copyright (c) 2012, 2018 by Delphix. All rights reserved.
  * Copyright (c) 2017 Datto Inc.
  * Copyright 2017 RackTop Systems.
  * Copyright (c) 2017 Open-E, Inc. All Rights Reserved.
@@ -58,6 +58,7 @@ int lzc_promote(const char *, char *, int);
 int lzc_destroy_snaps(nvlist_t *, boolean_t, nvlist_t **);
 int lzc_bookmark(nvlist_t *, nvlist_t **);
 int lzc_get_bookmarks(const char *, nvlist_t *, nvlist_t **);
+int lzc_get_bookmark_props(const char *, nvlist_t **);
 int lzc_destroy_bookmarks(nvlist_t *, nvlist_t **);
 int lzc_load_key(const char *, boolean_t, uint8_t *, uint_t);
 int lzc_unload_key(const char *);
@@ -66,6 +67,7 @@ int lzc_initialize(const char *, pool_initialize_func_t, nvlist_t *,
     nvlist_t **);
 int lzc_trim(const char *, pool_trim_func_t, uint64_t, boolean_t,
     nvlist_t *, nvlist_t **);
+int lzc_redact(const char *, const char *, nvlist_t *);
 
 int lzc_snaprange_space(const char *, const char *, uint64_t *);
 
@@ -87,6 +89,10 @@ int lzc_send_space(const char *, const char *, enum lzc_send_flags, uint64_t *);
 
 struct dmu_replay_record;
 
+int lzc_send_redacted(const char *, const char *, int, enum lzc_send_flags,
+    const char *);
+int lzc_send_resume_redacted(const char *, const char *, int,
+    enum lzc_send_flags, uint64_t, uint64_t, const char *);
 int lzc_receive(const char *, nvlist_t *, const char *, boolean_t, boolean_t,
     int);
 int lzc_receive_resumable(const char *, nvlist_t *, const char *, boolean_t,
@@ -100,6 +106,11 @@ int lzc_receive_with_cmdprops(const char *, nvlist_t *, nvlist_t *,
     uint8_t *, uint_t, const char *, boolean_t, boolean_t, boolean_t, int,
     const struct dmu_replay_record *, int, uint64_t *, uint64_t *,
     uint64_t *, nvlist_t **);
+int lzc_send_space(const char *, const char *, enum lzc_send_flags, uint64_t *);
+int lzc_send_space_resume_redacted(const char *, const char *,
+    enum lzc_send_flags, uint64_t, uint64_t, uint64_t, const char *,
+    int, uint64_t *);
+uint64_t lzc_send_progress(int);
 
 boolean_t lzc_exists(const char *);