[1/4] btrfs-progs: get_fsid_fd() for getting fsid using fd

Commit Message

Goldwyn Rodrigues Aug. 3, 2020, 8:30 p.m. UTC

From: Goldwyn Rodrigues <[e-mail]>

Add a function get_fsid_fd() to use an open file fd to get the
fsid of the mounted filesystem.

Signed-off-by: Goldwyn Rodrigues <[e-mail]>
---
 common/utils.c | 30 ++++++++++++++++--------------
 common/utils.h |  1 +
 2 files changed, 17 insertions(+), 14 deletions(-)

Patch

diff --git a/common/utils.c b/common/utils.c
index 9742c2e1..dbe1e806 100644
--- a/common/utils.c
+++ b/common/utils.c
@@ -1097,32 +1097,34 @@  out:
 	return ret;
 }
 
+int get_fsid_fd(int fd, u8 *fsid)
+{
+	int ret;
+	struct btrfs_ioctl_fs_info_args args;
+
+	ret = ioctl(fd, BTRFS_IOC_FS_INFO, &args);
+	if (ret < 0)
+		return -errno;
+
+	memcpy(fsid, args.fsid, BTRFS_FSID_SIZE);
+	return 0;
+}
+
 int get_fsid(const char *path, u8 *fsid, int silent)
 {
 	int ret;
 	int fd;
-	struct btrfs_ioctl_fs_info_args args;
 
 	fd = open(path, O_RDONLY);
 	if (fd < 0) {
-		ret = -errno;
 		if (!silent)
 			error("failed to open %s: %m", path);
-		goto out;
-	}
-
-	ret = ioctl(fd, BTRFS_IOC_FS_INFO, &args);
-	if (ret < 0) {
-		ret = -errno;
-		goto out;
+		return -errno;
 	}
 
-	memcpy(fsid, args.fsid, BTRFS_FSID_SIZE);
-	ret = 0;
+	ret = get_fsid_fd(fd, fsid);
+	close(fd);
 
-out:
-	if (fd != -1)
-		close(fd);
 	return ret;
 }
 
diff --git a/common/utils.h b/common/utils.h
index 43e7f471..e34bb5a4 100644
--- a/common/utils.h
+++ b/common/utils.h
@@ -75,6 +75,7 @@  void close_file_or_dir(int fd, DIR *dirstream);
 int get_fs_info(const char *path, struct btrfs_ioctl_fs_info_args *fi_args,
 		struct btrfs_ioctl_dev_info_args **di_ret);
 int get_fsid(const char *path, u8 *fsid, int silent);
+int get_fsid_fd(int fd, u8 *fsid);
 
 int get_label(const char *btrfs_dev, char *label);
 int set_label(const char *btrfs_dev, const char *label);