4 files changed, 51 insertions, 4 deletions

diff --git a/sbin/dump/dump.8 b/sbin/dump/dump.8
index 6759bda..a96995d 100644
--- a/sbin/dump/dump.8
+++ b/sbin/dump/dump.8
@@ -38,7 +38,7 @@
 .Nd file system backup
 .Sh SYNOPSIS
 .Nm
-.Op Fl 0123456789acLnSu
+.Op Fl 0123456789acLnrRSu
 .Op Fl B Ar records
 .Op Fl b Ar blocksize
 .Op Fl C Ar cachesize
@@ -258,6 +258,27 @@ notify all operators in the group
 .Dq operator
 by means similar to a
 .Xr wall 1 .
+.It Fl r
+Be rsync-friendly.
+Normally dump stores the date of the current
+and prior dump in numerous places throughout the dump.
+These scattered changes significantly slow down rsync or
+another incremental file transfer program when they are
+used to update a remote copy of a level 0 dump,
+since the date changes for each dump.
+This option sets both dates to the epoch, permitting
+rsync to be much more efficient when transferring a dump file.
+.It Fl R
+Be even more rsync-friendly.
+This option disables the storage of the actual inode access time
+(storing it instead as the inode's modified time).
+This option permits rsync to be even more efficient
+when transferring dumps generated from filesystems with numerous files
+which are not changing other than their access times.
+The
+.Fl R
+option also sets
+.Fl r .
 .It Fl S
 Display an estimate of the backup size and the number of
 tapes required, and exit without actually performing the dump.
diff --git a/sbin/dump/dump.h b/sbin/dump/dump.h
index d467668..73e2d01 100644
--- a/sbin/dump/dump.h
+++ b/sbin/dump/dump.h
@@ -75,6 +75,7 @@ int	etapes;		/* estimated number of tapes */
 int	nonodump;	/* if set, do not honor UF_NODUMP user flags */
 int	unlimited;	/* if set, write to end of medium */
 int	cachesize;	/* size of block cache in bytes */
+int	rsync_friendly;	/* be friendly with rsync */
 
 int	notify;		/* notify operator flag */
 int	blockswritten;	/* number of blocks written on current tape */
diff --git a/sbin/dump/main.c b/sbin/dump/main.c
index 827ffcc..63e4845 100644
--- a/sbin/dump/main.c
+++ b/sbin/dump/main.c
@@ -117,13 +117,14 @@ main(int argc, char *argv[])
 	if (TP_BSIZE / DEV_BSIZE == 0 || TP_BSIZE % DEV_BSIZE != 0)
 		quit("TP_BSIZE must be a multiple of DEV_BSIZE\n");
 	level = '0';
+	rsync_friendly = 0;
 
 	if (argc < 2)
 		usage();
 
 	obsolete(&argc, &argv);
 	while ((ch = getopt(argc, argv,
-	    "0123456789aB:b:C:cD:d:f:h:LnP:Ss:T:uWw")) != -1)
+	    "0123456789aB:b:C:cD:d:f:h:LnP:RrSs:T:uWw")) != -1)
 		switch (ch) {
 		/* dump level */
 		case '0': case '1': case '2': case '3': case '4':
@@ -189,6 +190,16 @@ main(int argc, char *argv[])
 			popenout = optarg;
 			break;
 
+		case 'r': /* store slightly less data to be friendly to rsync */
+			if (rsync_friendly < 1)
+				rsync_friendly = 1;
+			break;
+
+		case 'R': /* store even less data to be friendlier to rsync */
+			if (rsync_friendly < 2)
+				rsync_friendly = 2;
+			break;
+
 		case 'S':               /* exit after estimating # of tapes */
 			just_estimate = 1;
 			break;
@@ -236,6 +247,11 @@ main(int argc, char *argv[])
 		(void)fprintf(stderr, "\n");
 		exit(X_STARTUP);
 	}
+	if (rsync_friendly && (level>'0')) {
+		(void)fprintf(stderr, "%s %s\n", "rsync friendly options",
+		    "can be used only with level 0 dumps.");
+		exit(X_STARTUP);
+	}
 	if (Tflag && uflag) {
 	        (void)fprintf(stderr,
 		    "You cannot use the T and u flags together.\n");
@@ -384,7 +400,11 @@ main(int argc, char *argv[])
 	(void)gethostname(spcl.c_host, NAMELEN);
 	spcl.c_level = level - '0';
 	spcl.c_type = TS_TAPE;
-
+	if (rsync_friendly) {
+		/* don't store real dump times */
+		spcl.c_date = 0;
+		spcl.c_ddate = 0;
+	}
 	if (spcl.c_date == 0) {
 		tmsg = "the epoch\n";
 	} else {
@@ -393,7 +413,7 @@ main(int argc, char *argv[])
 	}
 	msg("Date of this level %c dump: %s", level, tmsg);
 
-	if (!Tflag)
+	if (!Tflag && (!rsync_friendly))
 	        getdumptime();		/* /etc/dumpdates snarfed */
 	if (spcl.c_ddate == 0) {
 		tmsg = "the epoch\n";
diff --git a/sbin/dump/traverse.c b/sbin/dump/traverse.c
index 211cfa6..f593244 100644
--- a/sbin/dump/traverse.c
+++ b/sbin/dump/traverse.c
@@ -842,6 +842,11 @@ writeheader(ino_t ino)
 {
 	int32_t sum, cnt, *lp;
 
+	if (rsync_friendly >= 2) {
+		/* don't track changes to access time */
+		spcl.c_atime = spcl.c_mtime;
+		spcl.c_atimensec = spcl.c_mtimensec;
+	}
 	spcl.c_inumber = ino;
 	spcl.c_magic = FS_UFS2_MAGIC;
 	spcl.c_checksum = 0;