1 files changed, 50 insertions, 0 deletions
diff --git a/src/udev/udev-builtin-btrfs.c b/src/udev/udev-builtin-btrfs.c
new file mode 100644
index 0000000..9b12aeb
--- /dev/null
+++ b/src/udev/udev-builtin-btrfs.c
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <fcntl.h>
+#include <linux/btrfs.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+
+#include "device-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "string-util.h"
+#include "strxcpyx.h"
+#include "udev-builtin.h"
+
+static int builtin_btrfs(UdevEvent *event, int argc, char *argv[], bool test) {
+        sd_device *dev = ASSERT_PTR(ASSERT_PTR(event)->dev);
+        struct btrfs_ioctl_vol_args args = {};
+        _cleanup_close_ int fd = -EBADF;
+        int r;
+
+        if (argc != 3 || !streq(argv[1], "ready"))
+                return log_device_error_errno(dev, SYNTHETIC_ERRNO(EINVAL), "Invalid arguments");
+
+        fd = open("/dev/btrfs-control", O_RDWR|O_CLOEXEC|O_NOCTTY);
+        if (fd < 0) {
+                if (ERRNO_IS_DEVICE_ABSENT(errno)) {
+                        /* Driver not installed? Then we aren't ready. This is useful in initrds that lack
+                         * btrfs.ko. After the host transition (where btrfs.ko will hopefully become
+                         * available) the device can be retriggered and will then be considered ready. */
+                        udev_builtin_add_property(dev, test, "ID_BTRFS_READY", "0");
+                        return 0;
+                }
+
+                return log_device_debug_errno(dev, errno, "Failed to open /dev/btrfs-control: %m");
+        }
+
+        strscpy(args.name, sizeof(args.name), argv[2]);
+        r = ioctl(fd, BTRFS_IOC_DEVICES_READY, &args);
+        if (r < 0)
+                return log_device_debug_errno(dev, errno, "Failed to call BTRFS_IOC_DEVICES_READY: %m");
+
+        udev_builtin_add_property(dev, test, "ID_BTRFS_READY", one_zero(r == 0));
+        return 0;
+}
+
+const UdevBuiltin udev_builtin_btrfs = {
+        .name = "btrfs",
+        .cmd = builtin_btrfs,
+        .help = "btrfs volume management",
+};