libbe(3): Add a destroy option for removing the origin

Currently origin snapshots are left behind when a BE is destroyed, whether
it was an auto-created snapshot or explicitly specified via, for example,
`bectl create -e be@mysnap ...`.

Removing it automatically could be argued as a POLA violation in some
circumstances, so provide a flag to be_destroy for it. An accompanying
option will be added to bectl(8) to utilize this.

Some minor style/consistency nits in the affected areas also addressed.

Reported by:	Shawn Webb
MFC after:	1 week

2 files changed, 24 insertions, 7 deletions

diff --git a/lib/libbe/be.c b/lib/libbe/be.c
index b07e791805b6..cf13e9fec9bd 100644
--- a/lib/libbe/be.c
+++ b/lib/libbe/be.c
@@ -203,13 +203,14 @@ be_destroy_cb(zfs_handle_t *zfs_hdl, void *data)
 int
 be_destroy(libbe_handle_t *lbh, const char *name, int options)
 {
+	char origin[BE_MAXPATHLEN], path[BE_MAXPATHLEN];
 	zfs_handle_t *fs;
-	char path[BE_MAXPATHLEN];
 	char *p;
 	int err, force, mounted;
 
 	p = path;
 	force = options & BE_DESTROY_FORCE;
+	*origin = '\0';
 
 	be_root_concat(lbh, name, path);
 
@@ -222,17 +223,21 @@ be_destroy(libbe_handle_t *lbh, const char *name, int options)
 			return (set_error(lbh, BE_ERR_DESTROYACT));
 
 		fs = zfs_open(lbh->lzh, p, ZFS_TYPE_FILESYSTEM);
+		if (fs == NULL)
+			return (set_error(lbh, BE_ERR_ZFSOPEN));
+		if ((options & BE_DESTROY_ORIGIN) != 0 &&
+		    zfs_prop_get(fs, ZFS_PROP_ORIGIN, origin, sizeof(origin),
+		    NULL, NULL, 0, 1) != 0)
+			return (set_error(lbh, BE_ERR_NOORIGIN));
 	} else {
-
 		if (!zfs_dataset_exists(lbh->lzh, path, ZFS_TYPE_SNAPSHOT))
 			return (set_error(lbh, BE_ERR_NOENT));
 
 		fs = zfs_open(lbh->lzh, p, ZFS_TYPE_SNAPSHOT);
+		if (fs == NULL)
+			return (set_error(lbh, BE_ERR_ZFSOPEN));
 	}
 
-	if (fs == NULL)
-		return (set_error(lbh, BE_ERR_ZFSOPEN));
-
 	/* Check if mounted, unmount if force is specified */
 	if ((mounted = zfs_is_mounted(fs, NULL)) != 0) {
 		if (force)
@@ -248,6 +253,17 @@ be_destroy(libbe_handle_t *lbh, const char *name, int options)
 		return (set_error(lbh, BE_ERR_UNKNOWN));
 	}
 
+	if (*origin != '\0') {
+		fs = zfs_open(lbh->lzh, origin, ZFS_TYPE_SNAPSHOT);
+		if (fs == NULL)
+			return (set_error(lbh, BE_ERR_ZFSOPEN));
+		err = zfs_destroy(fs, false);
+		if (err == EBUSY)
+			return (set_error(lbh, BE_ERR_DESTROYMNT));
+		else if (err != 0)
+			return (set_error(lbh, BE_ERR_UNKNOWN));
+	}
+
 	return (0);
 }
 
diff --git a/lib/libbe/be.h b/lib/libbe/be.h
index 265ce263cf55..dcf336d7423c 100644
--- a/lib/libbe/be.h
+++ b/lib/libbe/be.h
@@ -93,7 +93,8 @@ int be_rename(libbe_handle_t *, const char *, const char *);
 /* Bootenv removal functions */
 
 typedef enum {
-	BE_DESTROY_FORCE = 1 << 0,
+	BE_DESTROY_FORCE	= 1 << 0,
+	BE_DESTROY_ORIGIN	= 1 << 1,
 } be_destroy_opt_t;
 
 int be_destroy(libbe_handle_t *, const char *, int);
@@ -102,7 +103,7 @@ int be_destroy(libbe_handle_t *, const char *, int);
 
 typedef enum {
 	BE_MNT_FORCE		= 1 << 0,
-		BE_MNT_DEEP	= 1 << 1,
+	BE_MNT_DEEP		= 1 << 1,
 } be_mount_opt_t;
 
 int be_mount(libbe_handle_t *, char *, char *, int, char *);