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devmapper: Enable skip_block_zeroing

This makes the device mapper not zero out blocks allocated on the
thinp device. This is safe in our use case, as we access the device
via a filesystem that doesn't leak any uninitialized data to userspace.

This partially helps with https://github.com/dotcloud/docker/issues/3280
and should generally improve preformance on the devicemapper backend.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)

Alexander Larsson authored on 2014/02/09 15:25:34
Showing 1 changed files

graphdriver/devmapper/devmapper.go

History View file @ 695719b

@@ -324,7 +324,7 @@ func createPool(poolName string, dataFile, metadataFile *osFile) error {
 		return fmt.Errorf("Can't get data size")
 	}
 
-	params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768"
+	params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768 1 skip_block_zeroing"
 	if err := task.AddTarget(0, size/512, "thin-pool", params); err != nil {
 		return fmt.Errorf("Can't add target")
 	}

...	...	@@ -324,7 +324,7 @@ func createPool(poolName string, dataFile, metadataFile *osFile) error {
324	324	return fmt.Errorf("Can't get data size")
325	325	}
326	326
327		- params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768"
	327	+ params := metadataFile.Name() + " " + dataFile.Name() + " 128 32768 1 skip_block_zeroing"
328	328	if err := task.AddTarget(0, size/512, "thin-pool", params); err != nil {
329	329	return fmt.Errorf("Can't add target")
330	330	}