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snapshots/devmapper: suspend a device to avoid data corruption

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According to https://github.com/torvalds/linux/blob/v5.7/Documentation/admin-guide/device-mapper/thin-provisioning.rst#internal-snapshots;

> If the origin device that you wish to snapshot is active, you
> must suspend it before creating the snapshot to avoid corruption.

However the devmapper snapshotter was not doing that.

Signed-off-by: Kazuyoshi Kato <katokazu@amazon.com>
This commit is contained in:
Kazuyoshi Kato 2020-07-06 15:30:09 -07:00
parent c763f3afc2
commit c383436af7
1 changed files with 17 additions and 0 deletions
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17
snapshots/devmapper/pool_device.go
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@ -306,6 +306,23 @@ func (p *PoolDevice) CreateSnapshotDevice(ctx context.Context, deviceName string
return metaErr
}
// The base device must be suspend before taking a snapshot to
// avoid corruption.
// https://github.com/torvalds/linux/blob/v5.7/Documentation/admin-guide/device-mapper/thin-provisioning.rst#internal-snapshots
if p.IsLoaded(deviceName) {
log.G(ctx).Debugf("suspending %q before taking its snapshot", deviceName)
suspendErr := p.SuspendDevice(ctx, deviceName)
if suspendErr != nil {
return suspendErr
}
defer func() {
err := p.ResumeDevice(ctx, deviceName)
if err != nil {
log.G(ctx).WithError(err).Errorf("failed to resume base device %q after taking its snapshot", baseInfo.Name)
}
}()
}
// Create thin device snapshot
devErr = p.createSnapshot(ctx, baseInfo, snapInfo)
if devErr != nil {