From 4603dcf36b07230277474c6db76d76a128edaa5a Mon Sep 17 00:00:00 2001
From: Jacob Malevich <jam@daterainc.com>
Date: Fri, 14 Nov 2014 11:24:02 -0800
Subject: [PATCH] Option for returning only the uuid of the dev when doing a
 query-dev

Change-Id: Ia055da0516bc7baac836642fa1405b77adfc5139
Signed-off-by: Jacob Malevich <jam@daterainc.com>
---
 bcache.c    | 14 +++++++++++++-
 bcache.h    |  2 +-
 bcacheadm.c |  8 +++++---
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/bcache.c b/bcache.c
index 6ba5fad7..4b9c66c4 100644
--- a/bcache.c
+++ b/bcache.c
@@ -718,6 +718,12 @@ static void print_encode(char *in)
 			printf("%%%x", *pos);
 }
 
+static void show_uuid_only(struct cache_sb *sb) {
+	char uuid[40];
+	uuid_unparse(sb->uuid.b, uuid);
+	printf("%s\n", uuid);
+}
+
 static void show_super_common(struct cache_sb *sb, bool force_csum)
 {
 	char uuid[40];
@@ -864,7 +870,8 @@ void show_super_cache(struct cache_sb *sb, bool force_csum)
 	show_cache_member(sb, sb->nr_this_dev);
 }
 
-struct cache_sb *query_dev(char *dev, bool force_csum, bool print_sb)
+struct cache_sb *query_dev(char *dev, bool force_csum,
+		bool print_sb, bool uuid_only)
 {
 	struct cache_sb sb_stack, *sb = &sb_stack;
 	size_t bytes = sizeof(*sb);
@@ -890,6 +897,11 @@ struct cache_sb *query_dev(char *dev, bool force_csum, bool print_sb)
 		}
 	}
 
+	if(uuid_only) {
+		show_uuid_only(sb);
+		return sb;
+	}
+
 	if(print_sb) {
 		if (!SB_IS_BDEV(sb))
 			show_super_cache(sb, force_csum);
diff --git a/bcache.h b/bcache.h
index 3a551d1e..e10c73c7 100644
--- a/bcache.h
+++ b/bcache.h
@@ -57,7 +57,7 @@ long strtoul_or_die(const char *, size_t, const char *);
 void show_super_backingdev(struct cache_sb *, bool);
 void show_super_cache(struct cache_sb *, bool);
 
-struct cache_sb *query_dev(char *, bool, bool);
+struct cache_sb *query_dev(char *, bool, bool, bool);
 int list_cachesets(char *, bool);
 char *parse_array_to_list(char *const *);
 int register_bcache();
diff --git a/bcacheadm.c b/bcacheadm.c
index 76e53941..76ad0c6b 100644
--- a/bcacheadm.c
+++ b/bcacheadm.c
@@ -77,8 +77,9 @@ char *data_replicas = 0;
 char *tier = 0;
 
 
-/* super-show globals */
+/* query-dev globals */
 bool force_csum = false;
+bool uuid_only = false;
 
 /* probe globals */
 bool udev = false;
@@ -199,6 +200,7 @@ static NihOption bcache_register_options[] = {
 
 static NihOption query_devs_options[] = {
 	{'f', "force_csum", N_("force_csum"), NULL, NULL, &force_csum, NULL},
+	{'u', "uuid-only", N_("only print out the uuid for the devices, not the whole superblock"), NULL, NULL, &uuid_only, NULL},
 	NIH_OPTION_LAST
 };
 
@@ -363,7 +365,7 @@ int bcache_query_devs (NihCommand *command, char *const *args)
 
 
 	for (i = 0; args[i] != NULL; i++)
-		query_dev(args[i], force_csum, true);
+		query_dev(args[i], force_csum, true, uuid_only);
 }
 
 int bcache_status (NihCommand *command, char *const *args)
@@ -373,7 +375,7 @@ int bcache_status (NihCommand *command, char *const *args)
 	char *dev0 = NULL, *dev1 = NULL;
 
 	for (i = 0; args[i] != NULL; i++) {
-		struct cache_sb *sb = query_dev(args[i], false, false);
+		struct cache_sb *sb = query_dev(args[i], false, false, false);
 		struct cache_member *m = ((struct cache_member *) sb->d) +
 			sb->nr_this_dev;
 		long long unsigned cache_tier = CACHE_TIER(m);