btrfs-progs: inspect tree-stats: support to show a specified tree

tree-stats currently displays only some global trees and fs-tree 5. Add
support to show the stats of a specified tree.

Issue: #268
Signed-off-by: Chung-Chiang Cheng <cccheng@synology.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Documentation/btrfs-inspect-internal.rst

@@ -228,6 +228,9 @@ tree-stats [options] <device>
         -b
                 Print raw numbers in bytes.
 
+        -t <treeid>
+                Print stats only for the given treeid.
+
 EXIT STATUS
 -----------
 

cmds/inspect-tree-stats.c

@@ -35,6 +35,7 @@
 #include "common/help.h"
 #include "common/messages.h"
 #include "common/open-utils.h"
+#include "common/string-utils.h"
 #include "common/units.h"
 #include "cmds/commands.h"
 
@@ -441,6 +442,7 @@ static const char * const cmd_inspect_tree_stats_usage[] = {
 	"Print various stats for trees",
 	"",
 	OPTLINE("-b", "raw numbers in bytes"),
+	OPTLINE("-t <rootid>", "print only tree with the given rootid"),
 	NULL
 };
 
@@ -451,9 +453,10 @@ static int cmd_inspect_tree_stats(const struct cmd_struct *cmd,
 	struct btrfs_root *root;
 	int opt;
 	int ret = 0;
+	u64 tree_id = 0;
 
 	optind = 0;
-	while ((opt = getopt(argc, argv, "vb")) != -1) {
+	while ((opt = getopt(argc, argv, "vbt:")) != -1) {
 		switch (opt) {
 		case 'v':
 			verbose++;
@@ -461,6 +464,13 @@ static int cmd_inspect_tree_stats(const struct cmd_struct *cmd,
 		case 'b':
 			no_pretty = true;
 			break;
+		case 't':
+			tree_id = arg_strtou64(optarg);
+			if (!tree_id) {
+				error("unrecognized tree id: %s", optarg);
+				exit(1);
+			}
+			break;
 		default:
 			usage_unknown_option(cmd, argv);
 		}
@@ -485,6 +495,14 @@ static int cmd_inspect_tree_stats(const struct cmd_struct *cmd,
 		exit(1);
 	}
 
+	if (tree_id) {
+		pr_verbose(LOG_DEFAULT, "Calculating size of tree (%llu)\n", tree_id);
+		key.objectid = tree_id;
+		key.offset = (u64)-1;
+		ret = calc_root_size(root, &key, 1);
+		goto out;
+	}
+
 	pr_verbose(LOG_DEFAULT, "Calculating size of root tree\n");
 	key.objectid = BTRFS_ROOT_TREE_OBJECTID;
 	ret = calc_root_size(root, &key, 0);