btrfs: add ino_lookup example

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/fs/btrfs/ino_lookup/ino_lookup.c b/fs/btrfs/ino_lookup/ino_lookup.c
new file mode 100644
index 0000000..2233c9b
--- /dev/null
+++ b/fs/btrfs/ino_lookup/ino_lookup.c
@@ -0,0 +1,57 @@
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <linux/btrfs.h>
+#include <linux/btrfs_tree.h>
+#include <string.h>
+
+int main(int argc, char *argv[])
+{
+	if (argc < 3) {
+		fprintf(stderr, "usage: %s <mount point> <tree ID> <inode number | --tree-id>\n", argv[0]);
+		exit(EXIT_FAILURE);
+	}
+
+	const char *const path = argv[1];
+	unsigned long long treeid = strtoull(argv[2], NULL, 10);
+
+	unsigned long long ino;
+	if (strcmp(argv[3], "--tree-id") == 0) {
+		ino = BTRFS_FIRST_FREE_OBJECTID;
+		if (treeid > 0) {
+			printf("warning: the given tree ID value will be discarded.\n");
+		}
+		treeid = 0;
+	} else {
+		ino = strtoull(argv[3], NULL, 10);
+	}
+
+	int fd = open(path, O_RDONLY | O_DIRECTORY);
+	if (fd < 0) {
+		perror("open");
+		return 1;
+	}
+
+	// Check the README.md file on the args.
+	struct btrfs_ioctl_ino_lookup_args args;
+	memset(&args, 0, sizeof(args));
+	args.treeid = treeid;
+	args.objectid = ino;
+
+	if (ioctl(fd, BTRFS_IOC_INO_LOOKUP, &args) < 0) {
+		perror("BTRFS_IOC_INO_LOOKUP");
+		close(fd);
+		exit(EXIT_FAILURE);
+	}
+
+	printf("tree ID: %llu\n", args.treeid);
+	printf("inode: %llu\n", ino);
+	printf("path:  %s\n", args.name);
+
+	close(fd);
+	return 0;
+}