Get subvolume mounting/unmounting working way better

1 files changed, 51 insertions, 0 deletions

diff --git a/cmd/btrfs-mount/fuseutil.go b/cmd/btrfs-mount/fuseutil.go
new file mode 100644
index 0000000..c89e4b2
--- /dev/null
+++ b/cmd/btrfs-mount/fuseutil.go
@@ -0,0 +1,51 @@
+package main
+
+import (
+	"context"
+	"sync/atomic"
+
+	"github.com/datawire/dlib/dcontext"
+	"github.com/datawire/dlib/dgroup"
+	"github.com/datawire/dlib/dlog"
+	"github.com/jacobsa/fuse"
+)
+
+func Mount(ctx context.Context, mountpoint string, server fuse.Server, cfg *fuse.MountConfig) error {
+	grp := dgroup.NewGroup(ctx, dgroup.GroupConfig{
+		// Allow mountHandle.Join() returning to cause the
+		// "unmount" goroutine to quit.
+		ShutdownOnNonError: true,
+	})
+	mounted := uint32(1)
+	grp.Go("unmount", func(ctx context.Context) error {
+		<-ctx.Done()
+		var err error
+		var gotNil bool
+		// Keep retrying, because the FS might be busy.
+		for atomic.LoadUint32(&mounted) != 0 {
+			if _err := fuse.Unmount(mountpoint); _err == nil {
+				gotNil = true
+			} else if !gotNil {
+				err = _err
+			}
+		}
+		if gotNil {
+			return nil
+		}
+		return err
+	})
+	grp.Go("mount", func(ctx context.Context) error {
+		defer atomic.StoreUint32(&mounted, 0)
+
+		cfg.OpContext = ctx
+		cfg.ErrorLogger = dlog.StdLogger(ctx, dlog.LogLevelError)
+		cfg.DebugLogger = dlog.StdLogger(ctx, dlog.LogLevelDebug)
+
+		mountHandle, err := fuse.Mount(mountpoint, server, cfg)
+		if err != nil {
+			return err
+		}
+		return mountHandle.Join(dcontext.HardContext(ctx))
+	})
+	return grp.Wait()
+}