btrfs-progs: btrfstune: rework change_uuid

Change the change_uuid():
1) Remove new_chunk_tree_uuid parameter
   As chunk_tree_uuid is only internal used, no need to manual specify it.
   Use random generated UUID instead.

2) Don't use heap allocated memory for fs_info->new_fsid/chunk_tree_id.
   It's easy to forgot free or double free heap memory.
   Use stack memory instead.
   (In fact, I forgot to free them in previous patchset)

3) Print destination fsid.
   As now it's possible to change fsid to random uuid, it's better to print
   it out.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

1 files changed, 29 insertions, 34 deletions

diff --git a/btrfstune.c b/btrfstune.c
index 7b8090ab..36d7a009 100644
--- a/btrfstune.c
+++ b/btrfstune.c
@@ -293,36 +293,30 @@ static int change_fsid_done(struct btrfs_fs_info *fs_info)
 	return write_all_supers(fs_info->tree_root);
 }
 
-static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid,
-		       const char *new_chunk_uuid)
+/*
+ * Change fsid of a given fs.
+ *
+ * If new_fsid_str is not given, use a random generated UUID.
+ */
+static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid_str)
 {
+	uuid_t new_fsid;
+	uuid_t new_chunk_id;
+	char uuid_buf[BTRFS_UUID_UNPARSED_SIZE];
 	int ret = 0;
 
 	/* caller should do extra check on passed uuid */
-	if (new_fsid) {
-		/* allocated mem will be freed at close_ctree() */
-		fs_info->new_fsid = malloc(BTRFS_FSID_SIZE);
-		if (!fs_info->new_fsid) {
-			ret = -ENOMEM;
-			goto out;
-		}
-		ret = uuid_parse(new_fsid, fs_info->new_fsid);
-		if (ret < 0)
-			goto out;
-	}
+	if (new_fsid_str)
+		uuid_parse(new_fsid_str, new_fsid);
+	else
+		uuid_generate(new_fsid);
 
-	if (new_chunk_uuid) {
-		/* allocated mem will be freed at close_ctree() */
-		fs_info->new_chunk_tree_uuid = malloc(BTRFS_UUID_SIZE);
-		if (!fs_info->new_chunk_tree_uuid) {
-			ret = -ENOMEM;
-			goto out;
-		}
-		ret = uuid_parse(new_chunk_uuid, fs_info->new_chunk_tree_uuid);
-		if (ret < 0)
-			goto out;
-	}
+	uuid_generate(new_chunk_id);
+	fs_info->new_fsid = new_fsid;
+	fs_info->new_chunk_tree_uuid = new_chunk_id;
 
+	uuid_unparse_upper(new_fsid, uuid_buf);
+	printf("Changing fsid to %s\n", uuid_buf);
 	/* Now we can begin fsid change */
 	ret = change_fsid_prepare(fs_info);
 	if (ret < 0)
@@ -342,19 +336,20 @@ static int change_uuid(struct btrfs_fs_info *fs_info, const char *new_fsid,
 		goto out;
 	}
 
-	/* Last, change fsid in super, only fsid change needs this */
-	if (new_fsid) {
-		memcpy(fs_info->fs_devices->fsid, fs_info->new_fsid,
-		       BTRFS_FSID_SIZE);
-		memcpy(fs_info->super_copy->fsid, fs_info->new_fsid,
-		       BTRFS_FSID_SIZE);
-		ret = write_all_supers(fs_info->tree_root);
-		if (ret < 0)
-			goto out;
-	}
+	/* Last, change fsid in super */
+	memcpy(fs_info->fs_devices->fsid, fs_info->new_fsid,
+	       BTRFS_FSID_SIZE);
+	memcpy(fs_info->super_copy->fsid, fs_info->new_fsid,
+	       BTRFS_FSID_SIZE);
+	ret = write_all_supers(fs_info->tree_root);
+	if (ret < 0)
+		goto out;
 
 	/* Now fsid change is done */
 	ret = change_fsid_done(fs_info);
+	fs_info->new_fsid = NULL;
+	fs_info->new_chunk_tree_uuid = NULL;
+	printf("Fsid changed to %s\n", uuid_buf);
 out:
 	return ret;
 }