btrfs-progs: dump-tree: let --tree understand name of the tree

For practical purposes teach -t about the human readable names of the
trees in addition to the numerical id. The name syntax is flexible.

Signed-off-by: David Sterba <dsterba@suse.com>

Documentation/btrfs-inspect-internal.asciidoc

@@ -46,7 +46,16 @@ print only the uuid tree information, empty output if the tree does not exist
 -b <block_num>::::
 print info of the specified block only
 -t <tree_id>::::
-print only the tree with the specified numerical ID
+print only the tree with the specified ID, where the ID can be numerical or
+common name in a flexible human readable form
++
+The tree id name recognition rules:
+[options="compact"]
+* case does not matter
+* the C source definition, eg. BTRFS_ROOT_TREE_OBJECTID
+* short forms without BTRFS_ prefix, without _TREE and _OBJECTID suffix, eg. ROOT_TREE, ROOT
+* convenience aliases, eg. DEVICE for the DEV tree, CHECKSUM for CSUM
+* unrecognized ID is an error
 
 *inode-resolve* [-v] <ino> <path>::
 (needs root privileges)

cmds-inspect-dump-tree.c

@@ -106,6 +106,72 @@ static void print_old_roots(struct btrfs_super_block *super)
 	}
 }
 
+/*
+ * Convert a tree name from various forms to the numerical id if possible
+ * Accepted forms:
+ * - case does not matter
+ * - same as the key name, BTRFS_ROOT_TREE_OBJECTID
+ * - dtto shortened, BTRFS_ROOT_TREE
+ * - dtto without prefix, ROOT_TREE
+ * - common name, ROOT, CHUNK, EXTENT, ...
+ * - dtto alias, DEVICE for DEV, CHECKSUM for CSUM
+ *
+ * Returns 0 if the tree id was not recognized.
+ */
+static u64 treeid_from_string(const char *str, const char **end)
+{
+	int match = 0;
+	int i;
+	u64 id;
+	static struct treename {
+		const char *name;
+		u64 id;
+	} tn[] = {
+		{ "ROOT", BTRFS_ROOT_TREE_OBJECTID },
+		{ "EXTENT", BTRFS_EXTENT_TREE_OBJECTID },
+		{ "CHUNK", BTRFS_CHUNK_TREE_OBJECTID },
+		{ "DEVICE", BTRFS_DEV_TREE_OBJECTID },
+		{ "DEV", BTRFS_DEV_TREE_OBJECTID },
+		{ "FS_TREE", BTRFS_FS_TREE_OBJECTID },
+		{ "CSUM", BTRFS_CSUM_TREE_OBJECTID },
+		{ "CHECKSUM", BTRFS_CSUM_TREE_OBJECTID },
+		{ "QUOTA", BTRFS_QUOTA_TREE_OBJECTID },
+		{ "UUID", BTRFS_UUID_TREE_OBJECTID },
+		{ "FREE_SPACE", BTRFS_FREE_SPACE_TREE_OBJECTID },
+		{ "TREE_LOG_FIXUP", BTRFS_TREE_LOG_FIXUP_OBJECTID },
+		{ "TREE_LOG", BTRFS_TREE_LOG_OBJECTID },
+		{ "TREE_RELOC", BTRFS_TREE_RELOC_OBJECTID },
+		{ "DATA_RELOC", BTRFS_DATA_RELOC_TREE_OBJECTID }
+	};
+
+	if (strncasecmp("BTRFS_", str, strlen("BTRFS_")) == 0)
+		str += strlen("BTRFS_");
+
+	for (i = 0; i < ARRAY_SIZE(tn); i++) {
+		int len = strlen(tn[i].name);
+
+		if (strncasecmp(tn[i].name, str, len) == 0) {
+			id = tn[i].id;
+			match = 1;
+			str += len;
+			break;
+		}
+	}
+
+	if (!match)
+		return 0;
+
+	if (strncasecmp("_TREE", str, strlen("_TREE")) == 0)
+		str += strlen("_TREE");
+
+	if (strncasecmp("_OBJECTID", str, strlen("_OBJECTID")) == 0)
+		str += strlen("_OBJECTID");
+
+	*end = str;
+
+	return id;
+}
+
 const char * const cmd_inspect_dump_tree_usage[] = {
 	"btrfs inspect-internal dump-tree [options] device",
 	"Dump tree structures from a given device",
@@ -120,7 +186,7 @@ const char * const cmd_inspect_dump_tree_usage[] = {
 	"-R|--backups           same as --roots plus print backup root info",
 	"-u|--uuid              print only the uuid tree",
 	"-b|--block <block_num> print info from the specified block only",
-	"-t|--tree <tree_id>    print only the tree with the given tree_id",
+	"-t|--tree <tree_id>    print only tree with the given id (string or number)",
 	NULL
 };
 
@@ -183,7 +249,24 @@ int cmd_inspect_dump_tree(int argc, char **argv)
 			block_only = arg_strtou64(optarg);
 			break;
 		case 't':
-			tree_id = arg_strtou64(optarg);
+			if (string_is_numerical(optarg)) {
+				tree_id = arg_strtou64(optarg);
+			} else {
+				const char *end = NULL;
+
+				tree_id = treeid_from_string(optarg, &end);
+
+				if (*end) {
+					error("unexpected tree id suffix of '%s': %s\n",
+							optarg, end);
+					exit(1);
+				}
+			}
+			if (!tree_id) {
+				error("unrecognized tree id: %s\n",
+						optarg);
+				exit(1);
+			}
 			break;
 		default:
 			usage(cmd_inspect_dump_tree_usage);