From bb875bb9e4a5ae9ac1e1924efa9242ed625844a6 Mon Sep 17 00:00:00 2001
From: Alasdair Kergon <agk@redhat.com>
Date: Thu, 18 Sep 2008 18:34:53 +0000
Subject: [PATCH] Only resume devices in dm_tree_preload_children if size
 changes.

---
 WHATS_NEW_DM                |  7 ++++---
 libdm/ioctl/libdm-iface.c   | 11 +++++++++++
 libdm/ioctl/libdm-targets.h |  2 ++
 libdm/libdm-deptree.c       | 17 +++++++++++++----
 4 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/WHATS_NEW_DM b/WHATS_NEW_DM
index 7c9daeeec..6a443c13e 100644
--- a/WHATS_NEW_DM
+++ b/WHATS_NEW_DM
@@ -1,7 +1,8 @@
-Version 1.02.28 - 
-================================
+Version 1.02.28 - 18th September 2008
+=====================================
+  Only resume devices in dm_tree_preload_children if size changes.
   Extend deptree buffers so the largest possible device numbers fit.
-  Added generation of the versioned libdevmapper-event.so for LVM's test
+  Generate versioned libdevmapper-event.so.
   Underline longer report help text headings.
 
 Version 1.02.27 - 25th June 2008
diff --git a/libdm/ioctl/libdm-iface.c b/libdm/ioctl/libdm-iface.c
index fb54665cd..7366f08b1 100644
--- a/libdm/ioctl/libdm-iface.c
+++ b/libdm/ioctl/libdm-iface.c
@@ -1501,6 +1501,11 @@ static int _create_and_load_v4(struct dm_task *dmt)
 	return r;
 }
 
+uint64_t dm_task_get_existing_table_size(struct dm_task *dmt)
+{
+	return dmt->existing_table_size;
+}
+
 static int _reload_with_suppression_v4(struct dm_task *dmt)
 {
 	struct dm_task *task;
@@ -1534,6 +1539,12 @@ static int _reload_with_suppression_v4(struct dm_task *dmt)
 		return r;
 	}
 
+	/* Store existing table size */
+	t2 = task->head;
+	while (t2 && t2->next)
+		t2 = t2->next;
+	dmt->existing_table_size = t2 ? t2->start + t2->length : 0;
+
 	if ((task->dmi.v4->flags & DM_READONLY_FLAG) ? 1 : 0 != dmt->read_only)
 		goto no_match;
 
diff --git a/libdm/ioctl/libdm-targets.h b/libdm/ioctl/libdm-targets.h
index 3caa8dd6a..1bb9ce176 100644
--- a/libdm/ioctl/libdm-targets.h
+++ b/libdm/ioctl/libdm-targets.h
@@ -58,6 +58,7 @@ struct dm_task {
 	int no_open_count;
 	int skip_lockfs;
 	int suppress_identical_reload;
+	uint64_t existing_table_size;
 
 	char *uuid;
 };
@@ -69,5 +70,6 @@ struct cmd_data {
 };
 
 int dm_check_version(void);
+uint64_t dm_task_get_existing_table_size(struct dm_task *dmt);
 
 #endif
diff --git a/libdm/libdm-deptree.c b/libdm/libdm-deptree.c
index 8c4797d9e..d687d8fa5 100644
--- a/libdm/libdm-deptree.c
+++ b/libdm/libdm-deptree.c
@@ -99,6 +99,7 @@ struct load_properties {
 	uint32_t read_ahead_flags;
 
 	unsigned segment_count;
+	unsigned size_changed;
 	struct list segs;
 
 	const char *new_name;
@@ -603,6 +604,7 @@ struct dm_tree_node *dm_tree_add_new_dev(struct dm_tree *dtree,
 		dnode->props.major = major;
 		dnode->props.minor = minor;
 		dnode->props.new_name = NULL;
+		dnode->props.size_changed = 0;
 	} else if (strcmp(name, dnode->name)) {
 		/* Do we need to rename node? */
 		if (!(dnode->props.new_name = dm_pool_strdup(dtree->mem, name))) {
@@ -1494,6 +1496,13 @@ static int _load_node(struct dm_tree_node *dnode)
 		if (r && !dnode->info.inactive_table)
 			log_verbose("Suppressed %s identical table reload.",
 				    dnode->name);
+
+		if ((dnode->props.size_changed =
+		     (dm_task_get_existing_table_size(dmt) == seg_start) ? 0 : 1))
+			log_debug("Table size changed from %" PRIu64 " to %"
+				  PRIu64 " for %s",
+				  dm_task_get_existing_table_size(dmt),
+				  seg_start, dnode->name);
 	}
 
 	dnode->props.segment_count = 0;
@@ -1505,8 +1514,8 @@ out:
 }
 
 int dm_tree_preload_children(struct dm_tree_node *dnode,
-				 const char *uuid_prefix,
-				 size_t uuid_prefix_len)
+			     const char *uuid_prefix,
+			     size_t uuid_prefix_len)
 {
 	void *handle = NULL;
 	struct dm_tree_node *child;
@@ -1541,8 +1550,8 @@ int dm_tree_preload_children(struct dm_tree_node *dnode,
 			}
 		}
 
-		/* Resume device immediately if it has parents */
-		if (!dm_tree_node_num_children(child, 1))
+		/* Resume device immediately if it has parents and its size changed */
+		if (!dm_tree_node_num_children(child, 1) || !dnode->props.size_changed)
 			continue;
 
 		if (!child->info.inactive_table && !child->info.suspended)