Ensure we do not double-lock the same volume in create

When making containers, we want to lock all named volumes we are
adding the container to, to ensure they aren't removed from under
us while we are working. Unfortunately, this code did not account
for a container having the same volume mounted in multiple places
so it could deadlock. Add a map to ensure that we don't lock the
same name more than once to resolve this.

Fixes #8221

Signed-off-by: Matthew Heon <matthew.heon@pm.me>
This commit is contained in:
Matthew Heon
2020-11-11 15:57:06 -05:00
parent dc58d4e285
commit 0f637e09da
3 changed files with 16 additions and 0 deletions

View File

@ -1503,6 +1503,7 @@ func (c *Container) mountStorage() (_ string, deferredErr error) {
// config.
// Returns the volume that was mounted.
func (c *Container) mountNamedVolume(v *ContainerNamedVolume, mountpoint string) (*Volume, error) {
logrus.Debugf("Going to mount named volume %s", v.Name)
vol, err := c.runtime.state.Volume(v.Name)
if err != nil {
return nil, errors.Wrapf(err, "error retrieving named volume %s for container %s", v.Name, c.ID())

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@ -345,8 +345,15 @@ func (r *Runtime) setupContainer(ctx context.Context, ctr *Container) (_ *Contai
// Lock all named volumes we are adding ourself to, to ensure we can't
// use a volume being removed.
volsLocked := make(map[string]bool)
for _, namedVol := range ctrNamedVolumes {
toLock := namedVol
// Ensure that we don't double-lock a named volume that is used
// more than once.
if volsLocked[namedVol.Name()] {
continue
}
volsLocked[namedVol.Name()] = true
toLock.lock.Lock()
defer toLock.lock.Unlock()
}

View File

@ -540,4 +540,12 @@ VOLUME /test/`
session = podmanTest.Podman([]string{"run", "--rm", "-v", fmt.Sprintf("%s:%s:O", mountPath, mountDest), "--mount", fmt.Sprintf("type=tmpfs,target=%s", mountDest), ALPINE})
Expect(session.ExitCode()).To(Not(Equal(0)))
})
It("same volume in multiple places does not deadlock", func() {
volName := "testVol1"
session := podmanTest.Podman([]string{"run", "-t", "-i", "-v", fmt.Sprintf("%s:/test1", volName), "-v", fmt.Sprintf("%s:/test2", volName), "--rm", ALPINE, "sh", "-c", "mount | grep /test"})
session.WaitWithDefaultTimeout()
Expect(session.ExitCode()).To(Equal(0))
Expect(len(session.OutputToStringArray())).To(Equal(2))
})
})