Merge pull request containerd#8511 from dmcgowan/blockfile-snapshotter

Add blockfile snapshotter

cmd/containerd/builtins/builtins_linux.go

@@ -20,6 +20,7 @@ import (
 	_ "github.com/containerd/containerd/metrics/cgroups"
 	_ "github.com/containerd/containerd/metrics/cgroups/v2"
 	_ "github.com/containerd/containerd/runtime/v2/runc/options"
+	_ "github.com/containerd/containerd/snapshots/blockfile/plugin"
 	_ "github.com/containerd/containerd/snapshots/native/plugin"
 	_ "github.com/containerd/containerd/snapshots/overlay/plugin"
 )

cmd/containerd/builtins/builtins_unix.go

@@ -19,5 +19,6 @@
 package builtins
 
 import (
+	_ "github.com/containerd/containerd/snapshots/blockfile/plugin"
 	_ "github.com/containerd/containerd/snapshots/native/plugin"
 )

docs/snapshotters/README.md

@@ -10,10 +10,13 @@ Generic:
 - `overlayfs` (default): OverlayFS. This driver is akin to Docker/Moby's "overlay2" storage driver, but containerd's implementation is not called "overlay2".
 - `native`: Native file copying driver. Akin to Docker/Moby's "vfs" driver.
 
+Block-based:
+- `blockfile`: A driver using raw block files for each snapshot. Block files are copied from a parent or base empty block file. Mounting requires a virtual machine or support for loopback mounts.
+- `devmapper`: ext4/xfs device mapper. See [`devmapper.md`](./devmapper.md).
+
 Filesystem-specific:
 - `btrfs`: btrfs. Needs the plugin root (`/var/lib/containerd/io.containerd.snapshotter.v1.btrfs`) to be mounted as btrfs.
 - `zfs`: ZFS. Needs the plugin root (`/var/lib/containerd/io.containerd.snapshotter.v1.zfs`) to be mounted as ZFS. See also https://github.com/containerd/zfs .
-- `devmapper`: ext4/xfs device mapper. See [`devmapper.md`](./devmapper.md).
 
 [Deprecated](https://github.com/containerd/containerd/blob/main/RELEASES.md#deprecated-features):
 - `aufs`: AUFS. Deprecated since containerd 1.5. Removed in containerd 2.0. See also https://github.com/containerd/aufs .