From 5081181b5d89886389758cd42adc9b8251da327d Mon Sep 17 00:00:00 2001
From: Alasdair Kergon <agk@redhat.com>
Date: Fri, 9 Sep 2011 01:15:18 +0000
Subject: [PATCH] Append z to lv_attr if new blocks will be zeroed.

---
 lib/metadata/lv.c         | 10 +++++++++-
 lib/metadata/metadata.h   |  2 +-
 lib/metadata/thin_manip.c |  2 +-
 man/lvs.8.in              |  2 ++
 4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/lib/metadata/lv.c b/lib/metadata/lv.c
index 322727ebf..8434e45c7 100644
--- a/lib/metadata/lv.c
+++ b/lib/metadata/lv.c
@@ -308,9 +308,10 @@ char *lv_attr_dup(struct dm_pool *mem, const struct logical_volume *lv)
 {
 	percent_t snap_percent;
 	struct lvinfo info;
+	struct lv_segment *seg;
 	char *repstr;
 
-	if (!(repstr = dm_pool_zalloc(mem, 8))) {
+	if (!(repstr = dm_pool_zalloc(mem, 9))) {
 		log_error("dm_pool_alloc failed");
 		return 0;
 	}
@@ -405,6 +406,13 @@ char *lv_attr_dup(struct dm_pool *mem, const struct logical_volume *lv)
 	else
 		repstr[6] = '-';
 
+	if ((lv_is_thin_volume(lv) && (seg = first_seg(lv)) && seg->pool_lv && (seg = first_seg(seg->pool_lv))) ||
+	    (lv_is_thin_pool(lv) && (seg = first_seg(lv))) &&
+	    seg->zero_new_blocks)
+		repstr[7] = 'z';
+	else
+		repstr[7] = '-';
+
 out:
 	return repstr;
 }
diff --git a/lib/metadata/metadata.h b/lib/metadata/metadata.h
index 87e260477..e984ba83d 100644
--- a/lib/metadata/metadata.h
+++ b/lib/metadata/metadata.h
@@ -372,7 +372,7 @@ struct pv_list *find_pv_in_pv_list(const struct dm_list *pl,
 struct lv_segment *find_seg_by_le(const struct logical_volume *lv, uint32_t le);
 
 /* Find pool LV segment given a thin pool data or metadata segment. */
-struct lv_segment *find_pool_seg(struct lv_segment *seg);
+struct lv_segment *find_pool_seg(const struct lv_segment *seg);
 
 /*
  * Remove a dev_dir if present.
diff --git a/lib/metadata/thin_manip.c b/lib/metadata/thin_manip.c
index e8bf48c3d..2412db6c3 100644
--- a/lib/metadata/thin_manip.c
+++ b/lib/metadata/thin_manip.c
@@ -61,7 +61,7 @@ int detach_pool_lv(struct lv_segment *seg)
 	return remove_seg_from_segs_using_this_lv(seg->pool_lv, seg);
 }
 
-struct lv_segment *find_pool_seg(struct lv_segment *seg)
+struct lv_segment *find_pool_seg(const struct lv_segment *seg)
 {
         struct lv_segment *pool_seg;
 
diff --git a/man/lvs.8.in b/man/lvs.8.in
index 7ed72703b..cc4970939 100644
--- a/man/lvs.8.in
+++ b/man/lvs.8.in
@@ -94,6 +94,8 @@ for example, mirror images, mirror logs as well as mirrors themselves appear as
 equivalents using the md raid kernel driver all appear as (r).
 Snapshots using the original device-mapper driver appear as (s); whereas
 snapshots of thin volumes using the new thin provisioning driver appear as (t).
+.IP 8 3
+Newly-allocated data blocks are overwritten with blocks of (z)eroes before use.
 .RE
 .TP
 .I \-\-segments
-- 
2.43.5