kotovalexarian-likes-github/moby--moby
1
0
Fork 0
mirror of https://github.com/moby/moby.git synced 2022-11-09 12:21:53 -05:00
Code Releases Activity

aufs: remove mntL

Browse source 
Commit 5cd62852fa added a lock around call to unix.Mount() to
avoid the race in aufs kernel code related to xino file creation
and removal. While this is going to be fixed in the kernel, we still
need to support the current aufs, so some kind of fix is required.

A think a better fix (rather than a lock) is to add a random suffix
to the file name (note it is and was a separate file per mount,
never mind the same file name -- the file is created/opened and
removed instantly, so each mount deals with its own file).

With the suffix added, the possibility to hit the race is extremely
low, and we don't have to do any locking.

Note we don't add any more characters, instead we're replacing
`xino` with four random characters in the 0-9a-z range.

See also: https://sourceforge.net/p/aufs/mailman/message/36674769/

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin 2019-05-23 11:56:59 -07:00
parent dbd06522bd
commit e2989c4d48
1 changed files with 5 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
daemon/graphdriver/aufs/aufs.go
View file

@ -28,10 +28,12 @@ import (
"fmt"
"io"
"io/ioutil"
"math/rand"
"os"
"os/exec"
"path"
"path/filepath"
"strconv"
"strings"
"sync"
"time"
@ -80,7 +82,6 @@ type Driver struct {
pathCache map[string]string
naiveDiff graphdriver.DiffDriver
locker *locker.Locker
mntL sync.Mutex
}
// Init returns a new AUFS driver.
@ -618,14 +619,14 @@ func (a *Driver) aufsMount(ro []string, rw, target, mountLabel string) (err erro
bp += copy(b[bp:], layer)
}
opts := "dio,xino=/dev/shm/aufs.xino"
// random 4 characters in the 0-9a-z range (e.g. "g6dz")
rnd := strconv.FormatInt(int64(1e9+rand.Uint32()%1e9), 36)[1:5]
opts := "dio,xino=/dev/shm/aufs." + rnd
if useDirperm() {
opts += ",dirperm1"
}
data := label.FormatMountLabel(fmt.Sprintf("%s,%s", string(b[:bp]), opts), mountLabel)
a.mntL.Lock()
err = unix.Mount("none", target, "aufs", 0, data)
a.mntL.Unlock()
if err != nil {
err = errors.Wrap(err, "mount target="+target+" data="+data)
return
@ -641,9 +642,7 @@ func (a *Driver) aufsMount(ro []string, rw, target, mountLabel string) (err erro
bp += copy(b[bp:], layer)
}
data := label.FormatMountLabel(string(b[:bp]), mountLabel)
a.mntL.Lock()
err = unix.Mount("none", target, "aufs", unix.MS_REMOUNT, data)
a.mntL.Unlock()
if err != nil {
err = errors.Wrap(err, "mount target="+target+" flags=MS_REMOUNT data="+data)
return