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/sys/dmu_recv.h

@@ -33,6 +33,8 @@
 #include <sys/dsl_bookmark.h>
 #include <sys/dsl_dataset.h>
 #include <sys/spa.h>
+#include <sys/objlist.h>
+#include <sys/dsl_bookmark.h>
 
 extern const char *recv_clone_name;
 
@@ -44,6 +46,7 @@ typedef struct dmu_recv_cookie {
 	const char *drc_tosnap;
 	boolean_t drc_newfs;
 	boolean_t drc_byteswap;
+	uint64_t drc_featureflags;
 	boolean_t drc_force;
 	boolean_t drc_resumable;
 	boolean_t drc_raw;
@@ -51,20 +54,37 @@ typedef struct dmu_recv_cookie {
 	boolean_t drc_spill;
 	struct avl_tree *drc_guid_to_ds_map;
 	nvlist_t *drc_keynvl;
-	zio_cksum_t drc_cksum;
 	uint64_t drc_fromsnapobj;
 	uint64_t drc_newsnapobj;
 	uint64_t drc_ivset_guid;
 	void *drc_owner;
 	cred_t *drc_cred;
+	nvlist_t *drc_begin_nvl;
+
+	objset_t *drc_os;
+	vnode_t *drc_vp; /* The vnode to read the stream from */
+	uint64_t drc_voff; /* The current offset in the stream */
+	uint64_t drc_bytes_read;
+	/*
+	 * A record that has had its payload read in, but hasn't yet been handed
+	 * off to the worker thread.
+	 */
+	struct receive_record_arg *drc_rrd;
+	/* A record that has had its header read in, but not its payload. */
+	struct receive_record_arg *drc_next_rrd;
+	zio_cksum_t drc_cksum;
+	zio_cksum_t drc_prev_cksum;
+	int drc_err;
+	/* Sorted list of objects not to issue prefetches for. */
+	objlist_t *drc_ignore_objlist;
 } dmu_recv_cookie_t;
 
-int dmu_recv_begin(char *tofs, char *tosnap,
-    struct dmu_replay_record *drr_begin, boolean_t force, boolean_t resumable,
-    nvlist_t *localprops, nvlist_t *hidden_args, char *origin,
-    dmu_recv_cookie_t *drc);
-int dmu_recv_stream(dmu_recv_cookie_t *drc, struct vnode *vp, offset_t *voffp,
-    int cleanup_fd, uint64_t *action_handlep);
+int dmu_recv_begin(char *tofs, char *tosnap, dmu_replay_record_t *drr_begin,
+    boolean_t force, boolean_t resumable, nvlist_t *localprops,
+    nvlist_t *hidden_args, char *origin, dmu_recv_cookie_t *drc,
+    vnode_t *vp, offset_t *voffp);
+int dmu_recv_stream(dmu_recv_cookie_t *drc, int cleanup_fd,
+    uint64_t *action_handlep, offset_t *voffp);
 int dmu_recv_end(dmu_recv_cookie_t *drc, void *owner);
 boolean_t dmu_objset_is_receiving(objset_t *os);