MFV r289312: 2605 want to resume interrupted zfs send

Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed by: Xin Li <delphij@freebsd.org>
Reviewed by: Arne Jansen <sensille@gmx.net>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Matthew Ahrens <mahrens@delphix.com>

illumos/illumos-gate@9c3fd1216fa7fb02cfbc78a2518a686d54b48ab8

For more info, see:
 - slides http://www.slideshare.net/MatthewAhrens/openzfs-send-and-receive
 - video https://www.youtube.com/watch?v=iY44jPMvxog
 - manpage changes (for zfs resume -s and zfs send -t)
 - upcoming talk at the OpenZFS Developer Summit

The TL;DR is:
Use "zfs receive -s" to save the partially received state on failure.
On failure, get the receive token with "zfs get receive_resume_token <fs>"
Resume the send with "zfs send -t <token_value>"

Relnotes:	yes

1 files changed, 50 insertions, 19 deletions

diff --git a/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.c b/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.c
index 5ba660d..69d332a 100644
--- a/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.c
+++ b/cddl/contrib/opensolaris/lib/libzfs_core/common/libzfs_core.c
@@ -515,6 +515,13 @@ int
 lzc_send(const char *snapname, const char *from, int fd,
     enum lzc_send_flags flags)
 {
+	return (lzc_send_resume(snapname, from, fd, flags, 0, 0));
+}
+
+int
+lzc_send_resume(const char *snapname, const char *from, int fd,
+    enum lzc_send_flags flags, uint64_t resumeobj, uint64_t resumeoff)
+{
 	nvlist_t *args;
 	int err;
 
@@ -526,6 +533,10 @@ lzc_send(const char *snapname, const char *from, int fd,
 		fnvlist_add_boolean(args, "largeblockok");
 	if (flags & LZC_SEND_FLAG_EMBED_DATA)
 		fnvlist_add_boolean(args, "embedok");
+	if (resumeobj != 0 || resumeoff != 0) {
+		fnvlist_add_uint64(args, "resume_object", resumeobj);
+		fnvlist_add_uint64(args, "resume_offset", resumeoff);
+	}
 	err = lzc_ioctl(ZFS_IOC_SEND_NEW, snapname, args, NULL);
 	nvlist_free(args);
 	return (err);
@@ -583,22 +594,9 @@ recv_read(int fd, void *buf, int ilen)
 	return (0);
 }
 
-/*
- * The simplest receive case: receive from the specified fd, creating the
- * specified snapshot.  Apply the specified properties a "received" properties
- * (which can be overridden by locally-set properties).  If the stream is a
- * clone, its origin snapshot must be specified by 'origin'.  The 'force'
- * flag will cause the target filesystem to be rolled back or destroyed if
- * necessary to receive.
- *
- * Return 0 on success or an errno on failure.
- *
- * Note: this interface does not work on dedup'd streams
- * (those with DMU_BACKUP_FEATURE_DEDUP).
- */
-int
-lzc_receive(const char *snapname, nvlist_t *props, const char *origin,
-    boolean_t force, int fd)
+static int
+lzc_receive_impl(const char *snapname, nvlist_t *props, const char *origin,
+    boolean_t force, boolean_t resumable, int fd)
 {
 	/*
 	 * The receive ioctl is still legacy, so we need to construct our own
@@ -608,7 +606,6 @@ lzc_receive(const char *snapname, nvlist_t *props, const char *origin,
 	char *atp;
 	char *packed = NULL;
 	size_t size;
-	dmu_replay_record_t drr;
 	int error;
 
 	ASSERT3S(g_refcount, >, 0);
@@ -644,10 +641,9 @@ lzc_receive(const char *snapname, nvlist_t *props, const char *origin,
 		(void) strlcpy(zc.zc_string, origin, sizeof (zc.zc_string));
 
 	/* zc_begin_record is non-byteswapped BEGIN record */
-	error = recv_read(fd, &drr, sizeof (drr));
+	error = recv_read(fd, &zc.zc_begin_record, sizeof (zc.zc_begin_record));
 	if (error != 0)
 		goto out;
-	zc.zc_begin_record = drr.drr_u.drr_begin;
 
 	/* zc_cookie is fd to read from */
 	zc.zc_cookie = fd;
@@ -655,6 +651,8 @@ lzc_receive(const char *snapname, nvlist_t *props, const char *origin,
 	/* zc guid is force flag */
 	zc.zc_guid = force;
 
+	zc.zc_resumable = resumable;
+
 	/* zc_cleanup_fd is unused */
 	zc.zc_cleanup_fd = -1;
 
@@ -670,6 +668,39 @@ out:
 }
 
 /*
+ * The simplest receive case: receive from the specified fd, creating the
+ * specified snapshot.  Apply the specified properties as "received" properties
+ * (which can be overridden by locally-set properties).  If the stream is a
+ * clone, its origin snapshot must be specified by 'origin'.  The 'force'
+ * flag will cause the target filesystem to be rolled back or destroyed if
+ * necessary to receive.
+ *
+ * Return 0 on success or an errno on failure.
+ *
+ * Note: this interface does not work on dedup'd streams
+ * (those with DMU_BACKUP_FEATURE_DEDUP).
+ */
+int
+lzc_receive(const char *snapname, nvlist_t *props, const char *origin,
+    boolean_t force, int fd)
+{
+	return (lzc_receive_impl(snapname, props, origin, force, B_FALSE, fd));
+}
+
+/*
+ * Like lzc_receive, but if the receive fails due to premature stream
+ * termination, the intermediate state will be preserved on disk.  In this
+ * case, ECKSUM will be returned.  The receive may subsequently be resumed
+ * with a resuming send stream generated by lzc_send_resume().
+ */
+int
+lzc_receive_resumable(const char *snapname, nvlist_t *props, const char *origin,
+    boolean_t force, int fd)
+{
+	return (lzc_receive_impl(snapname, props, origin, force, B_TRUE, fd));
+}
+
+/*
  * Roll back this filesystem or volume to its most recent snapshot.
  * If snapnamebuf is not NULL, it will be filled in with the name
  * of the most recent snapshot.