f1d79d33b8
dmsetup does not discard blocks when removing a thin device. The unused blocks are reused by the thin-pool, but will remain allocated in the underlying device indefinitely. For loop device backed thin-pools, this results in "lost" disk space in the underlying file system as the blocks remain allocated in the loop device's backing file. This change adds an option, discard_blocks, to the devmapper snapshotter which causes the snapshotter to issue blkdiscard ioctls on the thin device before removal. With this option enabled, loop device setups will see disk space return to the underlying filesystem immediately on exiting a container. Fixes #5691 Signed-off-by: Kern Walster <walster@amazon.com>
42 lines
1.2 KiB
Go
42 lines
1.2 KiB
Go
// +build linux
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package blkdiscard
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import "os/exec"
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// Version returns the output of "blkdiscard --version"
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func Version() (string, error) {
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return blkdiscard("--version")
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}
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// BlkDiscard discards all blocks of a device.
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// devicePath is expected to be a fully qualified path.
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// BlkDiscard expects the caller to verify that the device is not in use.
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func BlkDiscard(devicePath string) (string, error) {
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return blkdiscard(devicePath)
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}
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func blkdiscard(args ...string) (string, error) {
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output, err := exec.Command("blkdiscard", args...).CombinedOutput()
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if err != nil {
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return "", err
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}
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return string(output), nil
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}
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