The following pull request was submitted through Github.
It can be accessed and reviewed at: https://github.com/lxc/lxd/pull/7160
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=== Description (from pull-request) ===
- Fixes migration from ZFS storage pools.
- Improves error reporting back to user and avoids hangs when an error occurs.
From 95193963ff710234baee7553b24d6d43dd550250 Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parr...@canonical.com>
Date: Wed, 8 Apr 2020 16:56:54 +0100
Subject: [PATCH 1/4] lxd/storage/drivers/generic/vfs: Log when creating
snapshots
Helpful when dir driver takes a long time creating snapshot.
Signed-off-by: Thomas Parrott <thomas.parr...@canonical.com>
---
lxd/storage/drivers/generic_vfs.go | 2 ++
1 file changed, 2 insertions(+)
diff --git a/lxd/storage/drivers/generic_vfs.go
b/lxd/storage/drivers/generic_vfs.go
index 56cdd9564b..88d81e8720 100644
--- a/lxd/storage/drivers/generic_vfs.go
+++ b/lxd/storage/drivers/generic_vfs.go
@@ -361,6 +361,7 @@ func genericVFSCreateVolumeFromMigration(d Driver,
initVolume func(vol Volume) (
}
// Create the snapshot itself.
+ d.Logger().Debug("Creating snapshot",
log.Ctx{"volName": snapVol.Name()})
err = d.CreateVolumeSnapshot(snapVol, op)
if err != nil {
return err
@@ -860,6 +861,7 @@ func genericVFSCopyVolume(d Driver, initVolume func(vol
Volume) (func(), error),
snapVol := NewVolume(d, d.Name(), vol.volType,
vol.contentType, fullSnapName, vol.config, vol.poolConfig)
// Create the snapshot itself.
+ d.Logger().Debug("Creating snapshot",
log.Ctx{"volName": snapVol.Name()})
err = d.CreateVolumeSnapshot(snapVol, op)
if err != nil {
return err
From 81bf97b9220eebca8915a40f6ae7f68d7521a90e Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parr...@canonical.com>
Date: Wed, 8 Apr 2020 18:17:16 +0100
Subject: [PATCH 2/4] lxd/storage/drivers/driver/zfs/volumes: Fix migrating VM
block volumes in MigrateVolume
Signed-off-by: Thomas Parrott <thomas.parr...@canonical.com>
---
lxd/storage/drivers/driver_zfs_volumes.go | 26 +++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/lxd/storage/drivers/driver_zfs_volumes.go
b/lxd/storage/drivers/driver_zfs_volumes.go
index e1e11fdddc..c2b7ed1996 100644
--- a/lxd/storage/drivers/driver_zfs_volumes.go
+++ b/lxd/storage/drivers/driver_zfs_volumes.go
@@ -1121,6 +1121,32 @@ 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.
+ 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)
+ if err != nil {
+ return err
+ }
+ if ourMount {
+ 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
From 4639ebf9fc73522537cf57094de17be5def76105 Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parr...@canonical.com>
Date: Wed, 8 Apr 2020 18:17:52 +0100
Subject: [PATCH 3/4] lxd/storage/memorypipe: Adds context support for
cancellation
Signed-off-by: Thomas Parrott <thomas.parr...@canonical.com>
---
lxd/storage/memorypipe/memory_pipe.go | 44 ++++++++++++++++++++-------
1 file changed, 33 insertions(+), 11 deletions(-)
diff --git a/lxd/storage/memorypipe/memory_pipe.go
b/lxd/storage/memorypipe/memory_pipe.go
index 79a1b03c6e..d8628816b3 100644
--- a/lxd/storage/memorypipe/memory_pipe.go
+++ b/lxd/storage/memorypipe/memory_pipe.go
@@ -1,6 +1,8 @@
package memorypipe
import (
+ "context"
+ "fmt"
"io"
)
@@ -21,17 +23,22 @@ type msg struct {
// connection to be used for multiple sessions.
type pipe struct {
ch chan msg
+ ctx context.Context
otherEnd *pipe
}
// Read reads from the pipe into p. Returns number of bytes read and any
errors.
func (p *pipe) Read(b []byte) (int, error) {
- msg := <-p.ch
- if msg.err == io.EOF {
- return -1, msg.err
+ select {
+ case msg := <-p.ch:
+ if msg.err == io.EOF {
+ return -1, msg.err
+ }
+ n := copy(b, msg.data)
+ return n, msg.err
+ case <-p.ctx.Done():
+ return -1, fmt.Errorf("Context done")
}
- n := copy(b, msg.data)
- return n, msg.err
}
// Write writes to the pipe from p. Returns number of bytes written and any
errors.
@@ -40,8 +47,13 @@ func (p *pipe) Write(b []byte) (int, error) {
data: append(b[:0:0], b...), // Create copy of b in case it is
modified externally.
err: nil,
}
- p.otherEnd.ch <- msg // Send msg to the other side's Read function.
- return len(msg.data), msg.err
+
+ select {
+ case p.otherEnd.ch <- msg: // Sent msg to the other side's Read
function.
+ return len(msg.data), msg.err
+ case <-p.ctx.Done():
+ return -1, fmt.Errorf("Context done")
+ }
}
// Close is unusual in that it doesn't actually close the pipe. Instead it
sends an io.EOF error
@@ -49,23 +61,33 @@ func (p *pipe) Write(b []byte) (int, error) {
// Each call to Close will indicate to the other side that a session has
ended, whilst allowing the
// reuse of a single persistent pipe for multiple sessions.
func (p *pipe) Close() error {
- p.otherEnd.ch <- msg{
+ msg := msg{
data: nil,
err: io.EOF, // Indicates to the other side's Read function
that session has ended.
}
+
+ select {
+ case p.otherEnd.ch <- msg: // Sent msg to the other side's Read
function.
+ return nil
+ case <-p.ctx.Done():
+ return fmt.Errorf("Context done")
+ }
+
return nil
}
// NewPipePair returns a pair of io.ReadWriterCloser pipes that are connected
together such that
// writes to one will appear as reads on the other and vice versa. Calling
Close() on one end will
// indicate to the other end that the session has ended.
-func NewPipePair() (io.ReadWriteCloser, io.ReadWriteCloser) {
+func NewPipePair(ctx context.Context) (io.ReadWriteCloser, io.ReadWriteCloser)
{
aEnd := &pipe{
- ch: make(chan msg, bufferSize),
+ ch: make(chan msg, bufferSize),
+ ctx: ctx,
}
bEnd := &pipe{
- ch: make(chan msg, bufferSize),
+ ch: make(chan msg, bufferSize),
+ ctx: ctx,
}
aEnd.otherEnd = bEnd
From d2a58f17e570e76517a74204cffd45dcb3d73c0e Mon Sep 17 00:00:00 2001
From: Thomas Parrott <thomas.parr...@canonical.com>
Date: Wed, 8 Apr 2020 18:18:14 +0100
Subject: [PATCH 4/4] lxd/storage/backend/lxd: memorypipe cancellation usage
Signed-off-by: Thomas Parrott <thomas.parr...@canonical.com>
---
lxd/storage/backend_lxd.go | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/lxd/storage/backend_lxd.go b/lxd/storage/backend_lxd.go
index 4621290a7f..06db8dd65a 100644
--- a/lxd/storage/backend_lxd.go
+++ b/lxd/storage/backend_lxd.go
@@ -1,6 +1,7 @@
package storage
import (
+ "context"
"fmt"
"io"
"os"
@@ -679,8 +680,10 @@ func (b *lxdBackend) CreateInstanceFromCopy(inst
instance.Instance, src instance
}
}
+ ctx, cancel := context.WithCancel(context.Background())
+
// Use in-memory pipe pair to simulate a connection between the
sender and receiver.
- aEnd, bEnd := memorypipe.NewPipePair()
+ aEnd, bEnd := memorypipe.NewPipePair(ctx)
// Negotiate the migration type to use.
offeredTypes := srcPool.MigrationTypes(contentType, false)
@@ -701,6 +704,7 @@ func (b *lxdBackend) CreateInstanceFromCopy(inst
instance.Instance, src instance
TrackProgress: true, // Do use a progress
tracker on sender.
}, op)
+ cancel()
aEndErrCh <- err
}()
@@ -712,6 +716,7 @@ func (b *lxdBackend) CreateInstanceFromCopy(inst
instance.Instance, src instance
TrackProgress: false, // Do not use a progress
tracker on receiver.
}, op)
+ cancel()
bEndErrCh <- err
}()
@@ -820,8 +825,10 @@ func (b *lxdBackend) RefreshInstance(inst
instance.Instance, src instance.Instan
snapshotNames = append(snapshotNames, snapShotName)
}
+ ctx, cancel := context.WithCancel(context.Background())
+
// Use in-memory pipe pair to simulate a connection between the
sender and receiver.
- aEnd, bEnd := memorypipe.NewPipePair()
+ aEnd, bEnd := memorypipe.NewPipePair(ctx)
// Negotiate the migration type to use.
offeredTypes := srcPool.MigrationTypes(contentType, true)
@@ -842,6 +849,7 @@ func (b *lxdBackend) RefreshInstance(inst
instance.Instance, src instance.Instan
TrackProgress: true, // Do use a progress
tracker on sender.
}, op)
+ cancel()
aEndErrCh <- err
}()
@@ -854,6 +862,7 @@ func (b *lxdBackend) RefreshInstance(inst
instance.Instance, src instance.Instan
TrackProgress: false, // Do not use a progress
tracker on receiver.
}, op)
+ cancel()
bEndErrCh <- err
}()
@@ -2261,8 +2270,10 @@ func (b *lxdBackend)
CreateCustomVolumeFromCopy(projectName string, volName stri
// to negotiate a common transfer method between pool types.
logger.Debug("CreateCustomVolumeFromCopy cross-pool mode detected")
+ ctx, cancel := context.WithCancel(context.Background())
+
// Use in-memory pipe pair to simulate a connection between the sender
and receiver.
- aEnd, bEnd := memorypipe.NewPipePair()
+ aEnd, bEnd := memorypipe.NewPipePair(ctx)
// Negotiate the migration type to use.
offeredTypes := srcPool.MigrationTypes(drivers.ContentTypeFS, false)
@@ -2283,6 +2294,7 @@ func (b *lxdBackend)
CreateCustomVolumeFromCopy(projectName string, volName stri
TrackProgress: true, // Do use a progress tracker on
sender.
}, op)
+ cancel()
aEndErrCh <- err
}()
@@ -2297,6 +2309,7 @@ func (b *lxdBackend)
CreateCustomVolumeFromCopy(projectName string, volName stri
}, op)
+ cancel()
bEndErrCh <- err
}()
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