1. docker
  2. Commit f9c8fa305e1501d8056f8744cb193a720aab0e13
Browse code

Perform fsmagic detection on driver's home-dir if it exists

The fsmagic check was always performed on "data-root" (`/var/lib/docker`),
not on the storage-driver's home directory (e.g. `/var/lib/docker/<somedriver>`).

This caused detection to be done on the wrong filesystem in situations
where `/var/lib/docker/<somedriver>` was a mount, and a different
filesystem than `/var/lib/docker` itself.

This patch checks if the storage-driver's home directory exists, and only
falls back to `/var/lib/docker` if it doesn't exist.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Sebastiaan van Stijn authored on 2017/12/05 07:45:26
Showing 5 changed files
daemon/graphdriver/aufs/aufs.go
History View file @ f9c8fa3
... ... 
@@ -89,7 +89,16 @@ func Init(root string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
89 89 
 		return nil, graphdriver.ErrNotSupported
90 90 
 	}
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-	fsMagic, err := graphdriver.GetFSMagic(root)
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+	// Perform feature detection on /var/lib/docker/aufs if it's an existing directory.
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+	// This covers situations where /var/lib/docker/aufs is a mount, and on a different
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+	// filesystem than /var/lib/docker.
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+	// If the path does not exist, fall back to using /var/lib/docker for feature detection.
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+	testdir := root
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+	if _, err := os.Stat(testdir); os.IsNotExist(err) {
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+		testdir = filepath.Dir(testdir)
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+	}
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+
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+	fsMagic, err := graphdriver.GetFSMagic(testdir)
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 	if err != nil {
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 		return nil, err
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 	}
daemon/graphdriver/btrfs/btrfs.go
History View file @ f9c8fa3
... ... 
@@ -51,7 +51,16 @@ type btrfsOptions struct {
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 // An error is returned if BTRFS is not supported.
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 func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (graphdriver.Driver, error) {
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-	fsMagic, err := graphdriver.GetFSMagic(home)
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+	// Perform feature detection on /var/lib/docker/btrfs if it's an existing directory.
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+	// This covers situations where /var/lib/docker/btrfs is a mount, and on a different
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+	// filesystem than /var/lib/docker.
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+	// If the path does not exist, fall back to using /var/lib/docker for feature detection.
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+	testdir := home
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+	if _, err := os.Stat(testdir); os.IsNotExist(err) {
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+		testdir = filepath.Dir(testdir)
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+	}
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+
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+	fsMagic, err := graphdriver.GetFSMagic(testdir)
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 	if err != nil {
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 		return nil, err
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 	}
daemon/graphdriver/driver_linux.go
History View file @ f9c8fa3
... ... 
@@ -3,8 +3,6 @@
3 3 
 package graphdriver
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 import (
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-	"path/filepath"
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-
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 	"github.com/docker/docker/pkg/mount"
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 	"golang.org/x/sys/unix"
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 )
... ... 
@@ -82,7 +80,7 @@ var (
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 // GetFSMagic returns the filesystem id given the path.
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 func GetFSMagic(rootpath string) (FsMagic, error) {
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 	var buf unix.Statfs_t
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-	if err := unix.Statfs(filepath.Dir(rootpath), &buf); err != nil {
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+	if err := unix.Statfs(rootpath, &buf); err != nil {
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 		return 0, err
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 	}
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 	return FsMagic(buf.Type), nil
daemon/graphdriver/overlay/overlay.go
History View file @ f9c8fa3
... ... 
@@ -10,6 +10,7 @@ import (
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 	"os"
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 	"os/exec"
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 	"path"
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+	"path/filepath"
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 	"strconv"
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 	"github.com/docker/docker/daemon/graphdriver"
... ... 
@@ -119,7 +120,16 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
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 		return nil, graphdriver.ErrNotSupported
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 	}
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-	fsMagic, err := graphdriver.GetFSMagic(home)
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+	// Perform feature detection on /var/lib/docker/overlay if it's an existing directory.
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+	// This covers situations where /var/lib/docker/overlay is a mount, and on a different
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+	// filesystem than /var/lib/docker.
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+	// If the path does not exist, fall back to using /var/lib/docker for feature detection.
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+	testdir := home
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+	if _, err := os.Stat(testdir); os.IsNotExist(err) {
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+		testdir = filepath.Dir(testdir)
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+	}
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+
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+	fsMagic, err := graphdriver.GetFSMagic(testdir)
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 	if err != nil {
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 		return nil, err
125 134 
 	}
daemon/graphdriver/overlay2/overlay.go
History View file @ f9c8fa3
... ... 
@@ -136,7 +136,16 @@ func Init(home string, options []string, uidMaps, gidMaps []idtools.IDMap) (grap
136 136 
 		return nil, err
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 	}
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-	fsMagic, err := graphdriver.GetFSMagic(home)
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+	// Perform feature detection on /var/lib/docker/overlay2 if it's an existing directory.
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+	// This covers situations where /var/lib/docker/overlay2 is a mount, and on a different
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+	// filesystem than /var/lib/docker.
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+	// If the path does not exist, fall back to using /var/lib/docker for feature detection.
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+	testdir := home
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+	if _, err := os.Stat(testdir); os.IsNotExist(err) {
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+		testdir = filepath.Dir(testdir)
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+	}
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+
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+	fsMagic, err := graphdriver.GetFSMagic(testdir)
140 149 
 	if err != nil {
141 150 
 		return nil, err
142 151 
 	}