From 9b9f1ae7726c2ee0e7eda76cd519f7d4921a12d9 Mon Sep 17 00:00:00 2001
From: Peter Rajnoha <prajnoha@redhat.com>
Date: Fri, 12 Feb 2016 13:53:06 +0100
Subject: [PATCH] format: format_text: add pv_needs_rewrite to format_handler
 and implemention for format_text

---
 lib/format_text/format-text.c | 22 ++++++++++++++++++++++
 lib/metadata/metadata.h       |  9 +++++++++
 2 files changed, 31 insertions(+)

diff --git a/lib/format_text/format-text.c b/lib/format_text/format-text.c
index 72026581b..666357c95 100644
--- a/lib/format_text/format-text.c
+++ b/lib/format_text/format-text.c
@@ -1439,6 +1439,27 @@ static int _text_pv_write(const struct format_type *fmt, struct physical_volume
 	return 1;
 }
 
+static int _text_pv_needs_rewrite(const struct format_type *fmt, struct physical_volume *pv,
+				  int *needs_rewrite)
+{
+	struct lvmcache_info *info;
+	uint32_t ext_vsn;
+
+	*needs_rewrite = 0;
+
+	if (!(info = lvmcache_info_from_pvid((const char *)&pv->id, 0))) {
+		log_error("Failed to find cached info for PV %s.", pv_dev_name(pv));
+		return 0;
+	}
+
+	ext_vsn = lvmcache_ext_version(info);
+
+	if (ext_vsn < PV_HEADER_EXTENSION_VSN)
+		*needs_rewrite = 1;
+
+	return 1;
+}
+
 static int _add_raw(struct dm_list *raw_list, struct device_area *dev_area)
 {
 	struct raw_list *rl;
@@ -2384,6 +2405,7 @@ static struct format_handler _text_handler = {
 	.pv_remove_metadata_area = _text_pv_remove_metadata_area,
 	.pv_resize = _text_pv_resize,
 	.pv_write = _text_pv_write,
+	.pv_needs_rewrite = _text_pv_needs_rewrite,
 	.vg_setup = _text_vg_setup,
 	.lv_setup = _text_lv_setup,
 	.create_instance = _text_create_text_instance,
diff --git a/lib/metadata/metadata.h b/lib/metadata/metadata.h
index 3f5f5aeae..f2b62e477 100644
--- a/lib/metadata/metadata.h
+++ b/lib/metadata/metadata.h
@@ -302,6 +302,15 @@ struct format_handler {
 	int (*pv_write) (const struct format_type * fmt,
 			 struct physical_volume * pv);
 
+	/*
+	 * Check if PV needs rewriting. This is used to check whether there are any
+	 * format-specific changes  before actually writing the PV (by calling pv_write).
+	 * With this, we can call pv_write conditionally only if it's really needed.
+	 */
+	int (*pv_needs_rewrite) (const struct format_type *fmt,
+				 struct physical_volume *pv,
+				 int *needs_rewrite);
+
 	/*
 	 * Tweak an already filled out a lv eg, check there
 	 * aren't too many extents.