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>
110 lines
2.9 KiB
Go
110 lines
2.9 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 devmapper
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import (
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"fmt"
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"os"
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"github.com/docker/go-units"
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"github.com/hashicorp/go-multierror"
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"github.com/pelletier/go-toml"
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"github.com/pkg/errors"
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)
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// Config represents device mapper configuration loaded from file.
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// Size units can be specified in human-readable string format (like "32KIB", "32GB", "32Tb")
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type Config struct {
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// Device snapshotter root directory for metadata
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RootPath string `toml:"root_path"`
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// Name for 'thin-pool' device to be used by snapshotter (without /dev/mapper/ prefix)
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PoolName string `toml:"pool_name"`
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// Defines how much space to allocate when creating base image for container
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BaseImageSize string `toml:"base_image_size"`
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BaseImageSizeBytes uint64 `toml:"-"`
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// Flag to async remove device using Cleanup() callback in snapshots GC
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AsyncRemove bool `toml:"async_remove"`
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// Whether to discard blocks when removing a thin device.
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DiscardBlocks bool `toml:"discard_blocks"`
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}
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// LoadConfig reads devmapper configuration file from disk in TOML format
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func LoadConfig(path string) (*Config, error) {
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if _, err := os.Stat(path); err != nil {
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if os.IsNotExist(err) {
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return nil, os.ErrNotExist
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}
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return nil, err
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}
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config := Config{}
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file, err := toml.LoadFile(path)
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if err != nil {
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return nil, errors.Wrapf(err, "failed to open devmapepr TOML: %s", path)
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}
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if err := file.Unmarshal(&config); err != nil {
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return nil, errors.Wrap(err, "failed to unmarshal devmapper TOML")
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}
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if err := config.parse(); err != nil {
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return nil, err
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}
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if err := config.Validate(); err != nil {
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return nil, err
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}
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return &config, nil
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}
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func (c *Config) parse() error {
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baseImageSize, err := units.RAMInBytes(c.BaseImageSize)
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if err != nil {
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return errors.Wrapf(err, "failed to parse base image size: '%s'", c.BaseImageSize)
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}
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c.BaseImageSizeBytes = uint64(baseImageSize)
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return nil
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}
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// Validate makes sure configuration fields are valid
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func (c *Config) Validate() error {
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var result *multierror.Error
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if c.PoolName == "" {
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result = multierror.Append(result, fmt.Errorf("pool_name is required"))
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}
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if c.RootPath == "" {
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result = multierror.Append(result, fmt.Errorf("root_path is required"))
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}
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if c.BaseImageSize == "" {
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result = multierror.Append(result, fmt.Errorf("base_image_size is required"))
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}
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return result.ErrorOrNil()
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}
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