From fc4b8629c62fa238af29e0dc640f1c7490e89934 Mon Sep 17 00:00:00 2001 From: Giuseppe Scrivano Date: Mon, 25 Jun 2018 13:49:49 +0200 Subject: [PATCH] containers-storage: add new option .fuse_program When specified the mount of the overlay file system is delegated to the specified command instead of mounting it directly. Signed-off-by: Giuseppe Scrivano --- docs/containers-storage.conf.5.md | 4 ++++ drivers/overlay/overlay.go | 38 ++++++++++++++++++++++++------- 2 files changed, 34 insertions(+), 8 deletions(-) diff --git a/docs/containers-storage.conf.5.md b/docs/containers-storage.conf.5.md index 3c63cfe783..243228c13a 100644 --- a/docs/containers-storage.conf.5.md +++ b/docs/containers-storage.conf.5.md @@ -89,6 +89,10 @@ Tells driver to wipe device (directlvm_device) even if device already has a file Specifies the filesystem type to use for the base device. (default: xfs) +**fuse_program**="" + +Specifies the path to a custom FUSE program to use instead for mounting the file system. + **log_level**="" Sets the log level of devicemapper. diff --git a/drivers/overlay/overlay.go b/drivers/overlay/overlay.go index 6b5f6912f7..468c4393d7 100644 --- a/drivers/overlay/overlay.go +++ b/drivers/overlay/overlay.go @@ -84,6 +84,7 @@ type overlayOptions struct { overrideKernelCheck bool imageStores []string quota quota.Quota + fuseProgram string } // Driver contains information about the home directory and the list of active mounts that are created using this driver. @@ -147,11 +148,16 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap return nil, err } - supportsDType, err := supportsOverlay(home, fsMagic, rootUID, rootGID) - if err != nil { - os.Remove(filepath.Join(home, linkDir)) - os.Remove(home) - return nil, errors.Wrap(err, "kernel does not support overlay fs") + var supportsDType bool + if opts.fuseProgram != "" { + supportsDType = true + } else { + supportsDType, err = supportsOverlay(home, fsMagic, rootUID, rootGID) + if err != nil { + os.Remove(filepath.Join(home, linkDir)) + os.Remove(home) + return nil, errors.Wrap(err, "kernel does not support overlay fs") + } } if err := mount.MakePrivate(home); err != nil { @@ -227,6 +233,13 @@ func parseOptions(options []string) (*overlayOptions, error) { } o.imageStores = append(o.imageStores, store) } + case ".fuse_program", "overlay.fuse_program", "overlay2.fuse_program": + logrus.Debugf("overlay: fuse_program=%s", val) + _, err := os.Stat(val) + if err != nil { + return nil, fmt.Errorf("overlay: can't stat FUSE program %s: %v", val, err) + } + o.fuseProgram = val default: return nil, fmt.Errorf("overlay: Unknown option %s", key) } @@ -236,6 +249,7 @@ func parseOptions(options []string) (*overlayOptions, error) { func supportsOverlay(home string, homeMagic graphdriver.FsMagic, rootUID, rootGID int) (supportsDType bool, err error) { // We can try to modprobe overlay first + exec.Command("modprobe", "overlay").Run() layerDir, err := ioutil.TempDir(home, "compat") @@ -663,7 +677,7 @@ func (d *Driver) Get(id, mountLabel string) (_ string, retErr error) { // the page size. The mount syscall fails if the mount data cannot // fit within a page and relative links make the mount data much // smaller at the expense of requiring a fork exec to chroot. - if len(mountData) > pageSize { + if len(mountData) > pageSize || d.options.fuseProgram != "" { //FIXME: We need to figure out to get this to work with additional stores opts = fmt.Sprintf("lowerdir=%s,upperdir=%s,workdir=%s", strings.Join(relLowers, ":"), path.Join(id, "diff"), path.Join(id, "work")) mountData = label.FormatMountLabel(opts, mountLabel) @@ -671,8 +685,16 @@ func (d *Driver) Get(id, mountLabel string) (_ string, retErr error) { return "", fmt.Errorf("cannot mount layer, mount label too large %d", len(mountData)) } - mount = func(source string, target string, mType string, flags uintptr, label string) error { - return mountFrom(d.home, source, target, mType, flags, label) + if d.options.fuseProgram != "" { + mount = func(source string, target string, mType string, flags uintptr, label string) error { + cmdRootless := exec.Command(d.options.fuseProgram, "-o", label, target) + cmdRootless.Dir = d.home + return cmdRootless.Run() + } + } else { + mount = func(source string, target string, mType string, flags uintptr, label string) error { + return mountFrom(d.home, source, target, mType, flags, label) + } } mountTarget = path.Join(id, "merged") }