From 19c865437a8c661045e61389dd6953047e2b9c82 Mon Sep 17 00:00:00 2001
From: Alasdair Kergon <agk@redhat.com>
Date: Wed, 7 Nov 2007 16:33:12 +0000
Subject: [PATCH] Prevent lvconvert -s from using same LV as origin and
 snapshot.

---
 WHATS_NEW                     | 1 +
 lib/metadata/merge.c          | 9 +++++++++
 lib/metadata/snapshot_manip.c | 5 +++++
 tools/lvconvert.c             | 6 ++++++
 4 files changed, 21 insertions(+)

diff --git a/WHATS_NEW b/WHATS_NEW
index 58fe520c4..e140b773e 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.29 -
 ==================================
+  Prevent lvconvert -s from using same LV as origin and snapshot.
   Fix human-readable output of odd numbers of sectors.
   Add pv_mda_free and vg_mda_free fields to reports for raw text format.
   Add LVM2 version to 'Generated by' comment in metadata.
diff --git a/lib/metadata/merge.c b/lib/metadata/merge.c
index 8b65fad14..eb88ad73c 100644
--- a/lib/metadata/merge.c
+++ b/lib/metadata/merge.c
@@ -119,6 +119,15 @@ int check_lv_segments(struct logical_volume *lv, int complete_vg)
 			}
 		}
 
+		if (seg_is_snapshot(seg)) {
+			if (seg->cow && seg->cow == seg->origin) {
+				log_error("LV %s: segment %u has same LV %s for "
+					  "both origin and snapshot",
+					  lv->name, seg_count, seg->cow->name);
+				r = 0;
+			}
+		}
+
 		for (s = 0; s < seg->area_count; s++) {
 			if (seg_type(seg, s) == AREA_UNASSIGNED) {
 				log_error("LV %s: segment %u has unassigned "
diff --git a/lib/metadata/snapshot_manip.c b/lib/metadata/snapshot_manip.c
index 9e84a2a05..aab85ef70 100644
--- a/lib/metadata/snapshot_manip.c
+++ b/lib/metadata/snapshot_manip.c
@@ -63,6 +63,11 @@ int vg_add_snapshot(const char *name, struct logical_volume *origin,
 		return 0;
 	}
 
+	if (cow == origin) {
+		log_error("Snapshot and origin LVs must differ.");
+		return 0;
+	}
+
 	if (!(snap = lv_create_empty(name ? name : "snapshot%d",
 				     lvid, LVM_READ | LVM_WRITE | VISIBLE_LV,
 				     ALLOC_INHERIT, 1, origin->vg))) {
diff --git a/tools/lvconvert.c b/tools/lvconvert.c
index 2864ea8e3..293f49b13 100644
--- a/tools/lvconvert.c
+++ b/tools/lvconvert.c
@@ -495,6 +495,12 @@ static int lvconvert_snapshot(struct cmd_context *cmd,
 		return 0;
 	}
 
+	if (org == lv) {
+		log_error("Unable to use \"%s\" as both snapshot and origin.",
+			  lv->name);
+		return 0;
+	}
+
 	if (org->status & (LOCKED|PVMOVE) || lv_is_cow(org)) {
 		log_error("Unable to create a snapshot of a %s LV.",
 			  org->status & LOCKED ? "locked" :