Fail add tree node when requested major/minor is used.

Check for major/minor collision is added in _add_dev_to_dtree()
where we already read info by uuid,
so in the case of requesting major/minor it queries device-mapper
by major/minor for device availability.

Fixes https://bugzilla.redhat.com/show_bug.cgi?id=204992

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.02.44 - 
 ====================================
+  Check if requested major/minor pair is already used.
   Fix incorrect return value in help function.
   Fix vgrename using UUID in case there are VGs with the same name.
   Fix segfault when invalid field given in reporting commands.

lib/activate/dev_manager.c

@@ -93,7 +93,8 @@ static int _read_only_lv(struct logical_volume *lv)
  * Low level device-layer operations.
  */
 static struct dm_task *_setup_task(const char *name, const char *uuid,
-				   uint32_t *event_nr, int task)
+				   uint32_t *event_nr, int task,
+				   uint32_t major, uint32_t minor)
 {
 	struct dm_task *dmt;
 
@@ -109,12 +110,17 @@ static struct dm_task *_setup_task(const char *name, const char *uuid,
 	if (event_nr)
 		dm_task_set_event_nr(dmt, *event_nr);
 
+	if (major) {
+		dm_task_set_major(dmt, major);
+		dm_task_set_minor(dmt, minor);
+	}
+
 	return dmt;
 }
 
 static int _info_run(const char *name, const char *dlid, struct dm_info *info,
 		     uint32_t *read_ahead, int mknodes, int with_open_count,
-		     int with_read_ahead)
+		     int with_read_ahead, uint32_t major, uint32_t minor)
 {
 	int r = 0;
 	struct dm_task *dmt;
@@ -122,7 +128,7 @@ static int _info_run(const char *name, const char *dlid, struct dm_info *info,
 
 	dmtask = mknodes ? DM_DEVICE_MKNODES : DM_DEVICE_INFO;
 
-	if (!(dmt = _setup_task(name, dlid, 0, dmtask)))
+	if (!(dmt = _setup_task(name, dlid, 0, dmtask, major, minor)))
 		return_0;
 
 	if (!with_open_count)
@@ -206,23 +212,28 @@ static int _info(const char *name, const char *dlid, int mknodes,
 {
 	if (!mknodes && dlid && *dlid) {
 		if (_info_run(NULL, dlid, info, read_ahead, 0, with_open_count,
-			      with_read_ahead) &&
+			      with_read_ahead, 0, 0) &&
 	    	    info->exists)
 			return 1;
 		else if (_info_run(NULL, dlid + sizeof(UUID_PREFIX) - 1, info,
 				   read_ahead, 0, with_open_count,
-				   with_read_ahead) &&
+				   with_read_ahead, 0, 0) &&
 			 info->exists)
 			return 1;
 	}
 
 	if (name)
 		return _info_run(name, NULL, info, read_ahead, mknodes,
-				 with_open_count, with_read_ahead);
+				 with_open_count, with_read_ahead, 0, 0);
 
 	return 0;
 }
 
+static int _info_by_dev(uint32_t major, uint32_t minor, struct dm_info *info)
+{
+	return _info_run(NULL, NULL, info, NULL, 0, 0, 0, major, minor);
+}
+
 int dev_manager_info(struct dm_pool *mem, const char *name,
 		     const struct logical_volume *lv, int with_mknodes,
 		     int with_open_count, int with_read_ahead,
@@ -252,7 +263,7 @@ static int _status_run(const char *name, const char *uuid,
 	char *type = NULL;
 	char *params = NULL;
 
-	if (!(dmt = _setup_task(name, uuid, 0, DM_DEVICE_STATUS)))
+	if (!(dmt = _setup_task(name, uuid, 0, DM_DEVICE_STATUS, 0, 0)))
 		return_0;
 
 	if (!dm_task_no_open_count(dmt))
@@ -339,7 +350,7 @@ static int _percent_run(struct dev_manager *dm, const char *name,
 	*percent = -1;
 
 	if (!(dmt = _setup_task(name, dlid, event_nr,
-				wait ? DM_DEVICE_WAITEVENT : DM_DEVICE_STATUS)))
+				wait ? DM_DEVICE_WAITEVENT : DM_DEVICE_STATUS, 0, 0)))
 		return_0;
 
 	if (!dm_task_no_open_count(dmt))
@@ -610,7 +621,7 @@ static int _add_dev_to_dtree(struct dev_manager *dm, struct dm_tree *dtree,
 			       struct logical_volume *lv, const char *layer)
 {
 	char *dlid, *name;
-	struct dm_info info;
+	struct dm_info info, info2;
 
 	if (!(name = build_dm_name(dm->mem, lv->vg->name, lv->name, layer)))
 		return_0;
@@ -624,6 +635,27 @@ static int _add_dev_to_dtree(struct dev_manager *dm, struct dm_tree *dtree,
 		return 0;
 	}
 
+	/*
+	 * For top level volumes verify that existing device match
+	 * requested major/minor and that major/minor pair is available for use
+	 */
+	if (!layer && lv->major != -1 && lv->minor != -1) {
+		if (info.exists && (info.major != lv->major || info.minor != lv->minor)) {
+			log_error("Volume %s (%" PRIu32 ":%" PRIu32")"
+				  " differs from already active device "
+				  "(%" PRIu32 ":%" PRIu32")",
+				  lv->name, lv->major, lv->minor, info.major, info.minor);
+			return 0;
+		}
+		if (!info.exists && _info_by_dev(lv->major, lv->minor, &info2) &&
+		    info2.exists) {
+			log_error("The requested major:minor pair "
+				  "(%" PRIu32 ":%" PRIu32") is already used",
+				  lv->major, lv->minor);
+			return 0;
+		}
+	}
+
 	if (info.exists && !dm_tree_add_dev(dtree, info.major, info.minor)) {
 		log_error("Failed to add device (%" PRIu32 ":%" PRIu32") to dtree",
 			  info.major, info.minor);