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aufs: apply dirperm1 by default if supported

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Automatically detect support for aufs `dirperm1` option and apply it.
`dirperm1` tells aufs to check the permission bits of the directory on the
topmost branch and ignore the permission bits on all lower branches.
It can be used to fix aufs' permission bug (i.e., upper layer having
broader mask than the lower layer).

More information about the bug can be found at https://github.com/docker/docker/issues/783
`dirperm1` man page is at: http://aufs.sourceforge.net/aufs3/man.html

Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com>
(cherry picked from commit 281abd2c8a)

Docker-DCO-1.1-Signed-off-by: Jessie Frazelle <jess@docker.com> (github: jfrazelle)
This commit is contained in:
Daniel, Dao Quang Minh
2015-03-30 12:02:48 -07:00
committed by Jessica Frazelle
parent 10425e83f2
commit af9dab70f8
1 changed files with 44 additions and 2 deletions
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daemon/graphdriver/aufs/aufs.go
+44 -2
View File
@@ -23,6 +23,7 @@ package aufs
import (
"bufio"
"fmt"
"io/ioutil"
"os"
"os/exec"
"path"
@@ -47,6 +48,9 @@ var (
graphdriver.FsMagicAufs,
}
backingFs = "<unknown>"
enableDirpermLock sync.Once
enableDirperm bool
)
func init() {
@@ -423,7 +427,11 @@ func (a *Driver) aufsMount(ro []string, rw, target, mountLabel string) (err erro
// Mount options are clipped to page size(4096 bytes). If there are more
// layers then these are remounted individually using append.
b := make([]byte, syscall.Getpagesize()-len(mountLabel)-54) // room for xino & mountLabel
offset := 54
if useDirperm() {
offset += len("dirperm1")
}
b := make([]byte, syscall.Getpagesize()-len(mountLabel)-offset) // room for xino & mountLabel
bp := copy(b, fmt.Sprintf("br:%s=rw", rw))
firstMount := true
@@ -447,7 +455,11 @@ func (a *Driver) aufsMount(ro []string, rw, target, mountLabel string) (err erro
}
if firstMount {
data := label.FormatMountLabel(fmt.Sprintf("%s,dio,xino=/dev/shm/aufs.xino", string(b[:bp])), mountLabel)
opts := "dio,xino=/dev/shm/aufs.xino"
if useDirperm() {
opts += ",dirperm1"
}
data := label.FormatMountLabel(fmt.Sprintf("%s,%s", string(b[:bp]), opts), mountLabel)
if err = mount("none", target, "aufs", 0, data); err != nil {
return
}
@@ -461,3 +473,33 @@ func (a *Driver) aufsMount(ro []string, rw, target, mountLabel string) (err erro
return
}
// useDirperm checks dirperm1 mount option can be used with the current
// version of aufs.
func useDirperm() bool {
enableDirpermLock.Do(func() {
base, err := ioutil.TempDir("", "docker-aufs-base")
if err != nil {
log.Errorf("error checking dirperm1: %v", err)
return
}
defer os.RemoveAll(base)
union, err := ioutil.TempDir("", "docker-aufs-union")
if err != nil {
log.Errorf("error checking dirperm1: %v", err)
return
}
defer os.RemoveAll(union)
opts := fmt.Sprintf("br:%s,dirperm1,xino=/dev/shm/aufs.xino", base)
if err := mount("none", union, "aufs", 0, opts); err != nil {
return
}
enableDirperm = true
if err := Unmount(union); err != nil {
log.Errorf("error checking dirperm1: failed to unmount %v", err)
}
})
return enableDirperm
}