For dm devices, kpartx uses an UUID check at partition removal
to make sure it only deletes partitions it previously created.
Non-DM parent devices such as loop devices don't generally have
a UUID.
Introduce a "fake" UUID for these devices to make sure kpartx
deletes only devices it had created previously. Otherwise kpartx
might e.g. delete LVM LVs that are inside a device it is trying
to delete partitions for. It seems to be wiser to make sure the
user delete these manually before running "kpartx -d".
With the fake UUID in place, we can re-introduce the UUID check
for non-DM device that was removed in the earlier patch
"kpartx: dm_remove_partmaps: support non-dm devices".
This disables also deletion of partition mappings created
by earlier versions of kpartx. If kpartx has been updated after
partition mappings were created, the "-f" flag can be used
to force delting these partitions, too.
Signed-off-by: Martin Wilck <mwilck@xxxxxxxx>
---
kpartx/devmapper.c | 2 +-
kpartx/kpartx.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/kpartx/devmapper.c b/kpartx/devmapper.c
index b714ba4e..4ab58ce9 100644
--- a/kpartx/devmapper.c
+++ b/kpartx/devmapper.c
@@ -511,7 +511,7 @@ do_foreach_partmaps (const char * mapname, const char *uuid,
/*
* skip if uuids don't match
*/
- if (is_dmdev && uuid && dm_compare_uuid(uuid, names->name)) {
+ if (uuid && dm_compare_uuid(uuid, names->name)) {
if (rd->verbose)
printf("%s: is not a kpartx partition. Not removing\n",
names->name);
diff --git a/kpartx/kpartx.c b/kpartx/kpartx.c
index ea728b42..587c3dfe 100644
--- a/kpartx/kpartx.c
+++ b/kpartx/kpartx.c
@@ -60,6 +60,31 @@ struct pt {
int ptct = 0;
int udev_sync = 0;
+/*
+ * UUID format for partitions created on non-DM devices
+ * ${UUID_PREFIX}devnode_${MAJOR}:${MINOR}_${NONDM_UUID_SUFFIX}"
+ * where ${UUID_PREFIX} is "part${PARTNO}-" (see devmapper.c).
+ *
+ * The suffix should be sufficiently unique to avoid incidental conflicts;
+ * the value below is a base64-encoded random number.
+ * The UUID format shouldn't be changed between kpartx releases.
+ */
+#define NONDM_UUID_PREFIX "devnode"
+#define NONDM_UUID_SUFFIX "Wh5pYvM"
+
+static char *
+nondm_create_uuid(dev_t devt)
+{
+#define NONDM_UUID_BUFLEN (34 + sizeof(NONDM_UUID_PREFIX) + \
+ sizeof(NONDM_UUID_SUFFIX))
+ static char uuid_buf[NONDM_UUID_BUFLEN];
+ snprintf(uuid_buf, sizeof(uuid_buf), "%s_%u:%u_%s",
+ NONDM_UUID_PREFIX, major(devt), minor(devt),
+ NONDM_UUID_SUFFIX);
+ uuid_buf[NONDM_UUID_BUFLEN-1] = '\0';
+ return uuid_buf;
+}
+
static void
addpts(char *t, ptreader f)
{
@@ -360,6 +385,15 @@ main(int argc, char **argv){
uuid = dm_mapuuid(mapname);
}
+ /*
+ * We are called for a non-DM device.
+ * Make up a fake UUID for the device, unless "-d -f" is given.
+ * This allows deletion of partitions created with older kpartx
+ * versions which didn't use the fake UUID during creation.
+ */
+ if (!uuid && !(what == DELETE && force_devmap))
+ uuid = nondm_create_uuid(buf.st_rdev);
+
if (!mapname)
mapname = device + off;
--
2.12.2
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