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store: simplify imagestore implementation
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simplify the imagestore implementation and use it as a first-class
store.  It reduces the amount of code to deal with an image store in
the driver (only overlay supports it at the moment).

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
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@giuseppe
giuseppe committed Dec 22, 2023
1 parent 1020ab6 commit 4f2c00e
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Showing 4 changed files with 132 additions and 177 deletions.
154 changes: 55 additions & 99 deletions drivers/overlay/overlay.go
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Original file line number Diff line number Diff line change
Expand Up @@ -309,16 +309,6 @@ func isNetworkFileSystem(fsMagic graphdriver.FsMagic) bool {
// If overlay filesystem is not supported on the host, a wrapped graphdriver.ErrNotSupported is returned as error.
// If an overlay filesystem is not supported over an existing filesystem then a wrapped graphdriver.ErrIncompatibleFS is returned.
func Init(home string, options graphdriver.Options) (graphdriver.Driver, error) {
// If custom --imagestore is selected never
// ditch the original graphRoot, instead add it as
// additionalImageStore so its images can still be
// read and used.
if options.ImageStore != "" {
graphRootAsAdditionalStore := fmt.Sprintf("AdditionalImageStore=%s", options.ImageStore)
options.DriverOptions = append(options.DriverOptions, graphRootAsAdditionalStore)
// complete base name with driver name included
options.ImageStore = filepath.Join(options.ImageStore, "overlay")
}
opts, err := parseOptions(options.DriverOptions)
if err != nil {
return nil, err
Expand Down Expand Up @@ -862,22 +852,15 @@ func (d *Driver) Status() [][2]string {
// Metadata returns meta data about the overlay driver such as
// LowerDir, UpperDir, WorkDir and MergeDir used to store data.
func (d *Driver) Metadata(id string) (map[string]string, error) {
dir, imagestore, _ := d.dir2(id)
dir := d.dir(id)
if _, err := os.Stat(dir); err != nil {
return nil, err
}
workDirBase := dir
if imagestore != "" {
if _, err := os.Stat(dir); err != nil {
return nil, err
}
workDirBase = imagestore
}

metadata := map[string]string{
"WorkDir": path.Join(workDirBase, "work"),
"MergedDir": path.Join(workDirBase, "merged"),
"UpperDir": path.Join(workDirBase, "diff"),
"WorkDir": path.Join(dir, "work"),
"MergedDir": path.Join(dir, "merged"),
"UpperDir": path.Join(dir, "diff"),
}

lowerDirs, err := d.getLowerDirs(id)
Expand Down Expand Up @@ -991,8 +974,10 @@ func (d *Driver) Create(id, parent string, opts *graphdriver.CreateOpts) (retErr
return d.create(id, parent, opts, true)
}

func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, disableQuota bool) (retErr error) {
dir, imageStore, _ := d.dir2(id)
func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, readOnly bool) (retErr error) {
dir, homedir, _ := d.dir2(id, readOnly)

disableQuota := readOnly

uidMaps := d.uidMaps
gidMaps := d.gidMaps
Expand All @@ -1003,7 +988,7 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, disable
}

// Make the link directory if it does not exist
if err := idtools.MkdirAllAs(path.Join(d.home, linkDir), 0o755, 0, 0); err != nil {
if err := idtools.MkdirAllAs(path.Join(homedir, linkDir), 0o755, 0, 0); err != nil {
return err
}

Expand All @@ -1020,20 +1005,8 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, disable
if err := idtools.MkdirAllAndChownNew(path.Dir(dir), 0o755, idPair); err != nil {
return err
}
workDirBase := dir
if imageStore != "" {
workDirBase = imageStore
if err := idtools.MkdirAllAndChownNew(path.Dir(imageStore), 0o755, idPair); err != nil {
return err
}
}
if parent != "" {
parentBase, parentImageStore, inAdditionalStore := d.dir2(parent)
// If parentBase path is additional image store, select the image contained in parentBase.
// See https://github.com/containers/podman/issues/19748
if parentImageStore != "" && !inAdditionalStore {
parentBase = parentImageStore
}
parentBase := d.dir(parent)
st, err := system.Stat(filepath.Join(parentBase, "diff"))
if err != nil {
return err
Expand All @@ -1054,23 +1027,13 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, disable
if err := idtools.MkdirAllAndChownNew(dir, 0o700, idPair); err != nil {
return err
}
if imageStore != "" {
if err := idtools.MkdirAllAndChownNew(imageStore, 0o700, idPair); err != nil {
return err
}
}

defer func() {
// Clean up on failure
if retErr != nil {
if err2 := os.RemoveAll(dir); err2 != nil {
logrus.Errorf("While recovering from a failure creating a layer, error deleting %#v: %v", dir, err2)
}
if imageStore != "" {
if err2 := os.RemoveAll(workDirBase); err2 != nil {
logrus.Errorf("While recovering from a failure creating a layer, error deleting %#v: %v", workDirBase, err2)
}
}
}
}()

Expand All @@ -1093,11 +1056,6 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, disable
if err := d.quotaCtl.SetQuota(dir, quota); err != nil {
return err
}
if imageStore != "" {
if err := d.quotaCtl.SetQuota(imageStore, quota); err != nil {
return err
}
}
}

perms := defaultPerms
Expand All @@ -1106,30 +1064,22 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, disable
}

if parent != "" {
parentBase, parentImageStore, inAdditionalStore := d.dir2(parent)
// If parentBase path is additional image store, select the image contained in parentBase.
// See https://github.com/containers/podman/issues/19748
if parentImageStore != "" && !inAdditionalStore {
parentBase = parentImageStore
}
parentBase := d.dir(parent)
st, err := system.Stat(filepath.Join(parentBase, "diff"))
if err != nil {
return err
}
perms = os.FileMode(st.Mode())
}

if err := idtools.MkdirAs(path.Join(workDirBase, "diff"), perms, rootUID, rootGID); err != nil {
if err := idtools.MkdirAs(path.Join(dir, "diff"), perms, rootUID, rootGID); err != nil {
return err
}

lid := generateID(idLength)

linkBase := path.Join("..", id, "diff")
if imageStore != "" {
linkBase = path.Join(imageStore, "diff")
}
if err := os.Symlink(linkBase, path.Join(d.home, linkDir, lid)); err != nil {
if err := os.Symlink(linkBase, path.Join(homedir, linkDir, lid)); err != nil {
return err
}

Expand All @@ -1138,10 +1088,10 @@ func (d *Driver) create(id, parent string, opts *graphdriver.CreateOpts, disable
return err
}

if err := idtools.MkdirAs(path.Join(workDirBase, "work"), 0o700, rootUID, rootGID); err != nil {
if err := idtools.MkdirAs(path.Join(dir, "work"), 0o700, rootUID, rootGID); err != nil {
return err
}
if err := idtools.MkdirAs(path.Join(workDirBase, "merged"), 0o700, rootUID, rootGID); err != nil {
if err := idtools.MkdirAs(path.Join(dir, "merged"), 0o700, rootUID, rootGID); err != nil {
return err
}

Expand Down Expand Up @@ -1223,26 +1173,39 @@ func (d *Driver) getLower(parent string) (string, error) {
}

func (d *Driver) dir(id string) string {
p, _, _ := d.dir2(id)
p, _, _ := d.dir2(id, false)
return p
}

func (d *Driver) dir2(id string) (string, string, bool) {
newpath := path.Join(d.home, id)
imageStore := ""
func (d *Driver) getAllImageStores() []string {
additionalImageStores := d.AdditionalImageStores()
if d.imageStore != "" {
imageStore = path.Join(d.imageStore, id)
additionalImageStores = append([]string{d.imageStore}, additionalImageStores...)
}
return additionalImageStores
}

func (d *Driver) dir2(id string, useImageStore bool) (string, string, bool) {
var homedir string

if useImageStore && d.imageStore != "" {
homedir = path.Join(d.imageStore, d.name)
} else {
homedir = d.home
}

newpath := path.Join(homedir, id)

if _, err := os.Stat(newpath); err != nil {
for _, p := range d.AdditionalImageStores() {
for _, p := range d.getAllImageStores() {
l := path.Join(p, d.name, id)
_, err = os.Stat(l)
if err == nil {
return l, imageStore, true
return l, homedir, true
}
}
}
return newpath, imageStore, false
return newpath, homedir, false
}

func (d *Driver) getLowerDirs(id string) ([]string, error) {
Expand Down Expand Up @@ -1452,14 +1415,11 @@ func (d *Driver) Get(id string, options graphdriver.MountOpts) (string, error) {
}

func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountOpts) (_ string, retErr error) {
dir, imageStore, inAdditionalStore := d.dir2(id)
dir, _, inAdditionalStore := d.dir2(id, false)
if _, err := os.Stat(dir); err != nil {
return "", err
}
workDirBase := dir
if imageStore != "" {
workDirBase = imageStore
}

readWrite := !inAdditionalStore

if !d.SupportsShifting() || options.DisableShifting {
Expand Down Expand Up @@ -1564,7 +1524,7 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
}()

composeFsLayers := []string{}
composeFsLayersDir := filepath.Join(workDirBase, "composefs-layers")
composeFsLayersDir := filepath.Join(dir, "composefs-layers")
maybeAddComposefsMount := func(lowerID string, i int, readWrite bool) (string, error) {
composefsBlob := d.getComposefsData(lowerID)
_, err = os.Stat(composefsBlob)
Expand Down Expand Up @@ -1598,7 +1558,7 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
return dest, nil
}

diffDir := path.Join(workDirBase, "diff")
diffDir := path.Join(dir, "diff")

if dest, err := maybeAddComposefsMount(id, 0, readWrite); err != nil {
return "", err
Expand All @@ -1616,7 +1576,7 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
lower := ""
newpath := path.Join(d.home, l)
if st, err := os.Stat(newpath); err != nil {
for _, p := range d.AdditionalImageStores() {
for _, p := range d.getAllImageStores() {
lower = path.Join(p, d.name, l)
if st2, err2 := os.Stat(lower); err2 == nil {
if !permsKnown {
Expand Down Expand Up @@ -1684,21 +1644,25 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
optsList = append(optsList, "metacopy=on", "redirect_dir=on")
}

if len(absLowers) == 0 {
absLowers = append(absLowers, path.Join(dir, "empty"))
}

// user namespace requires this to move a directory from lower to upper.
rootUID, rootGID, err := idtools.GetRootUIDGID(options.UidMaps, options.GidMaps)
if err != nil {
return "", err
}

if len(absLowers) == 0 {
empty := path.Join(dir, "empty")
if err := idtools.MkdirAs(empty, 0o700, rootUID, rootGID); err != nil {
return "", err
}
absLowers = append(absLowers, empty)
}

if err := idtools.MkdirAllAs(diffDir, perms, rootUID, rootGID); err != nil {
return "", err
}

mergedDir := path.Join(workDirBase, "merged")
mergedDir := path.Join(dir, "merged")
// Create the driver merged dir
if err := idtools.MkdirAs(mergedDir, 0o700, rootUID, rootGID); err != nil && !os.IsExist(err) {
return "", err
Expand All @@ -1716,7 +1680,7 @@ func (d *Driver) get(id string, disableShifting bool, options graphdriver.MountO
}
}()

workdir := path.Join(workDirBase, "work")
workdir := path.Join(dir, "work")

if d.options.mountProgram == "" && unshare.IsRootless() {
optsList = append(optsList, "userxattr")
Expand Down Expand Up @@ -2193,12 +2157,8 @@ func (d *Driver) getComposefsData(id string) string {
}

func (d *Driver) getDiffPath(id string) (string, error) {
dir, imagestore, _ := d.dir2(id)
base := dir
if imagestore != "" {
base = imagestore
}
return redirectDiffIfAdditionalLayer(path.Join(base, "diff"))
dir := d.dir(id)
return redirectDiffIfAdditionalLayer(path.Join(dir, "diff"))
}

func (d *Driver) getLowerDiffPaths(id string) ([]string, error) {
Expand Down Expand Up @@ -2289,12 +2249,8 @@ func (d *Driver) AdditionalImageStores() []string {
// by toContainer to those specified by toHost.
func (d *Driver) UpdateLayerIDMap(id string, toContainer, toHost *idtools.IDMappings, mountLabel string) error {
var err error
dir, imagestore, _ := d.dir2(id)
base := dir
if imagestore != "" {
base = imagestore
}
diffDir := filepath.Join(base, "diff")
dir := d.dir(id)
diffDir := filepath.Join(dir, "diff")

rootUID, rootGID := 0, 0
if toHost != nil {
Expand Down
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