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=== Description (from pull-request) ===
This PR changes the way that `genericVFSMigrateVolume` detects if a VM root device exists as a disk image in the instance's config filesystem (and needs to be excluded when rsyncing that volume to the target) or whether it exists as a block device outside of the filesystem's mount path.
This allows us to avoid a pre-mount of snapshot volumes, as previously it required thid to activate the volume in order to ascertain whether the root disk was a disk image or a block device.
From f57ba566ce6073ab40ddf129296bcb7dc1d74ffd Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parr...@canonical.com>
Date: Tue, 5 May 2020 15:55:25 +0100
Subject: [PATCH 1/2] lxd/storage/drivers/generic/vfs: Dont require access to
block device when excluding root image file from rsync in
genericVFSMigrateVolume
Signed-off-by: Thomas Parrott <thomas.parr...@canonical.com>
---
lxd/storage/drivers/generic_vfs.go | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/lxd/storage/drivers/generic_vfs.go
b/lxd/storage/drivers/generic_vfs.go
index eaee1fb6df..b08e691df7 100644
--- a/lxd/storage/drivers/generic_vfs.go
+++ b/lxd/storage/drivers/generic_vfs.go
@@ -144,20 +144,21 @@ func genericVFSMigrateVolume(d Driver, s *state.State,
vol Volume, conn io.ReadW
var rsyncArgs []string
- // For VM volumes, if the root volume disk path is a file image then
exclude it from being transferred via
- // rsync, it will be transferred later using a different method.
+ // For VM volumes, if the root volume disk path is a file image in the
volume's mount path then exclude it
+ // from being transferred via rsync during the filesystem volume
transfer, as it will be transferred later
+ // using a different method.
if vol.IsVMBlock() {
if volSrcArgs.MigrationType.FSType !=
migration.MigrationFSType_BLOCK_AND_RSYNC {
return ErrNotSupported
}
- path, err := d.GetVolumeDiskPath(vol)
+ diskPath, err := d.GetVolumeDiskPath(vol)
if err != nil {
return errors.Wrapf(err, "Error getting VM block volume
disk path")
}
- if !shared.IsBlockdevPath(path) {
- rsyncArgs = []string{"--exclude", filepath.Base(path)}
+ if strings.HasPrefix(diskPath, vol.MountPath()) {
+ rsyncArgs = []string{"--exclude",
filepath.Base(diskPath)}
}
} else if volSrcArgs.MigrationType.FSType !=
migration.MigrationFSType_RSYNC {
return ErrNotSupported
From ad18bd16e4882bd1308ba6de63dc6bede0fe6c44 Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parr...@canonical.com>
Date: Tue, 5 May 2020 16:16:50 +0100
Subject: [PATCH 2/2] lxd/storage/drivers/driver/zfs/volumes: Updates
MigrateVolume to avoid need to premount snapshot volume
This is now done inside genericVFSMigrateVolume and the block device doesn't
need to be accessible from the start for rsync exclusion see 47b8fa8cb
Signed-off-by: Thomas Parrott <thomas.parr...@canonical.com>
---
lxd/storage/drivers/driver_zfs_volumes.go | 18 ++----------------
1 file changed, 2 insertions(+), 16 deletions(-)
diff --git a/lxd/storage/drivers/driver_zfs_volumes.go
b/lxd/storage/drivers/driver_zfs_volumes.go
index b9f88d13d8..ea0a35ce3c 100644
--- a/lxd/storage/drivers/driver_zfs_volumes.go
+++ b/lxd/storage/drivers/driver_zfs_volumes.go
@@ -1182,10 +1182,8 @@ func (d *zfs) RenameVolume(vol Volume, newVolName
string, op *operations.Operati
func (d *zfs) MigrateVolume(vol Volume, conn io.ReadWriteCloser, volSrcArgs
*migration.VolumeSourceArgs, op *operations.Operation) error {
// Handle simple rsync and block_and_rsync through generic.
if volSrcArgs.MigrationType.FSType == migration.MigrationFSType_RSYNC
|| volSrcArgs.MigrationType.FSType == migration.MigrationFSType_BLOCK_AND_RSYNC
{
- // We need to mount the parent volume before calling
genericVFSMigrateVolume for two reasons.
- // 1. In order to get the block device disk path to read from
the device must be activated.
- // 2. If copying snapshots the parent volume must be activated
before the snapshot volume's block
- // device can be made visible.
+ // Before doing a generic volume migration, we need to ensure
volume (or snap volume parent) is
+ // activated to avoid issues activating the snapshot volume
device.
parent, _, _ :=
shared.InstanceGetParentAndSnapshotName(vol.Name())
parentVol := NewVolume(d, d.Name(), vol.volType,
vol.contentType, parent, vol.config, vol.poolConfig)
ourMount, err := d.MountVolume(parentVol, op)
@@ -1196,18 +1194,6 @@ func (d *zfs) MigrateVolume(vol Volume, conn
io.ReadWriteCloser, volSrcArgs *mig
defer d.UnmountVolume(parentVol, op)
}
- // In addition to above, if the volume we are sending is a
snapshot, we also need to mount that
- // so that genericVFSMigrateVolume can discover its block
device (same reason as 1. above).
- if vol.IsSnapshot() {
- ourMount, err = d.MountVolumeSnapshot(vol, op)
- if err != nil {
- return err
- }
- if ourMount {
- defer d.UnmountVolumeSnapshot(vol, op)
- }
- }
-
return genericVFSMigrateVolume(d, d.state, vol, conn,
volSrcArgs, op)
} else if volSrcArgs.MigrationType.FSType !=
migration.MigrationFSType_ZFS {
return ErrNotSupported
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