From fef66e67a0004cd0bfa27c23dd37b2eb1552b963 Mon Sep 17 00:00:00 2001
From: Turbo Fredriksson <turbo@bayour.com>
Date: Fri, 5 Sep 2014 23:29:36 +0200
Subject: [PATCH] 2668: turbo/issue-2666 - Allow for "zfs receive" to skip
 existing snapshots by adding the option "-s" to zfs receive.

Signed-off-by: Turbo Fredriksson <turbo@bayour.com>

Closes: #2666
---
 cmd/zfs/zfs_main.c           | 11 +++++++----
 include/libzfs.h             |  3 +++
 lib/libzfs/libzfs_sendrecv.c | 16 ++++++++++++++--
 man/man8/zfs.8               |  8 ++++----
 4 files changed, 28 insertions(+), 10 deletions(-)

diff --git a/cmd/zfs/zfs_main.c b/cmd/zfs/zfs_main.c
index 5ba31139a504..bb06755a36ef 100644
--- a/cmd/zfs/zfs_main.c
+++ b/cmd/zfs/zfs_main.c
@@ -247,9 +247,9 @@ get_usage(zfs_help_t idx)
 	case HELP_PROMOTE:
 		return (gettext("\tpromote <clone-filesystem>\n"));
 	case HELP_RECEIVE:
-		return (gettext("\treceive [-vnFu] <filesystem|volume|"
+		return (gettext("\treceive [-vnFus] <filesystem|volume|"
 		"snapshot>\n"
-		"\treceive [-vnFu] [-d | -e] <filesystem>\n"));
+		"\treceive [-vnFus] [-d | -e] <filesystem>\n"));
 	case HELP_RENAME:
 		return (gettext("\trename [-f] <filesystem|volume|snapshot> "
 		    "<filesystem|volume|snapshot>\n"
@@ -3853,7 +3853,7 @@ zfs_do_send(int argc, char **argv)
 }
 
 /*
- * zfs receive [-vnFu] [-d | -e] <fs@snap>
+ * zfs receive [-vnFus] [-d | -e] <fs@snap>
  *
  * Restore a backup stream from stdin.
  */
@@ -3864,8 +3864,11 @@ zfs_do_receive(int argc, char **argv)
 	recvflags_t flags = { 0 };
 
 	/* check options */
-	while ((c = getopt(argc, argv, ":denuvF")) != -1) {
+	while ((c = getopt(argc, argv, ":denuvFs")) != -1) {
 		switch (c) {
+		case 's':
+			flags.skip = B_TRUE;
+			break;
 		case 'd':
 			flags.isprefix = B_TRUE;
 			break;
diff --git a/include/libzfs.h b/include/libzfs.h
index 86578d8ad82d..c0eea4a2f7af 100644
--- a/include/libzfs.h
+++ b/include/libzfs.h
@@ -674,6 +674,9 @@ typedef struct recvflags {
 
 	/* do not mount file systems as they are extracted (private) */
 	boolean_t nomount;
+
+	/* skip existing snapshots */
+	boolean_t skip;
 } recvflags_t;
 
 extern int zfs_receive(libzfs_handle_t *, const char *, recvflags_t *,
diff --git a/lib/libzfs/libzfs_sendrecv.c b/lib/libzfs/libzfs_sendrecv.c
index 70870f766fbf..a691c52c7a24 100644
--- a/lib/libzfs/libzfs_sendrecv.c
+++ b/lib/libzfs/libzfs_sendrecv.c
@@ -2862,13 +2862,14 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 		zfs_handle_t *zhp;
 
 		/*
-		 * Destination fs exists.  Therefore this should either
+		 * Destination fs exists (and we have not been asked to
+		 * skip existing snapshots). Therefore this should either
 		 * be an incremental, or the stream specifies a new fs
 		 * (full stream or clone) and they want us to blow it
 		 * away (and have therefore specified -F and removed any
 		 * snapshots).
 		 */
-		if (stream_wantsnewfs) {
+		if (stream_wantsnewfs && !flags->skip) {
 			if (!flags->force) {
 				zcmd_free_nvlists(&zc);
 				zfs_error_aux(hdl, dgettext(TEXT_DOMAIN,
@@ -2956,6 +2957,17 @@ zfs_receive_one(libzfs_handle_t *hdl, int infd, const char *tosnap,
 	zc.zc_begin_record = drr_noswap->drr_u.drr_begin;
 	zc.zc_cookie = infd;
 	zc.zc_guid = flags->force;
+
+	if (zfs_dataset_exists(hdl, zc.zc_value, ZFS_TYPE_SNAPSHOT) &&
+	    flags->skip) {
+		(void) printf("skipping snapshot %s - %s already exists\n",
+				drrb->drr_toname, zc.zc_value);
+		(void) fflush(stdout);
+
+		zcmd_free_nvlists(&zc);
+		return (recv_skip(hdl, infd, flags->byteswap));
+	}
+
 	if (flags->verbose) {
 		(void) printf("%s %s stream of %s into %s\n",
 		    flags->dryrun ? "would receive" : "receiving",
diff --git a/man/man8/zfs.8 b/man/man8/zfs.8
index 69200fc49be3..b376ecfbab19 100644
--- a/man/man8/zfs.8
+++ b/man/man8/zfs.8
@@ -184,12 +184,12 @@ zfs \- configures ZFS file systems
 
 .LP
 .nf
-\fBzfs\fR \fBreceive | recv\fR [\fB-vnFu\fR] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR
+\fBzfs\fR \fBreceive | recv\fR [\fB-vnFus\fR] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR
 .fi
 
 .LP
 .nf
-\fBzfs\fR \fBreceive | recv\fR [\fB-vnFu\fR] [\fB-d\fR|\fB-e\fR] \fIfilesystem\fR
+\fBzfs\fR \fBreceive | recv\fR [\fB-vnFus\fR] [\fB-d\fR|\fB-e\fR] \fIfilesystem\fR
 .fi
 
 .LP
@@ -3059,11 +3059,11 @@ then the receiving system must have that feature enabled as well. See
 .ne 2
 .mk
 .na
-\fB\fBzfs receive\fR [\fB-vnFu\fR] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR\fR
+\fB\fBzfs receive\fR [\fB-vnFus\fR] \fIfilesystem\fR|\fIvolume\fR|\fIsnapshot\fR\fR
 .ad
 .br
 .na
-\fB\fBzfs receive\fR [\fB-vnFu\fR] [\fB-d\fR|\fB-e\fR] \fIfilesystem\fR\fR
+\fB\fBzfs receive\fR [\fB-vnFus\fR] [\fB-d\fR|\fB-e\fR] \fIfilesystem\fR\fR
 .ad
 .sp .6
 .RS 4n