block: introduce backup-top filter driver
Backup-top filter caches write operations and does copy-before-write operations. The driver will be used in backup instead of write-notifiers. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-id: 20191001131409.14202-5-vsementsov@virtuozzo.com Reviewed-by: Max Reitz <mreitz@redhat.com> Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Vladimir Sementsov-Ogievskiy
Max Reitz
parent
0f4b02b73e
commit
7df7868b96
@ -42,6 +42,7 @@ block-obj-y += block-copy.o
|
||||
block-obj-y += crypto.o
|
||||
|
||||
block-obj-y += aio_task.o
|
||||
block-obj-y += backup-top.o
|
||||
|
||||
common-obj-y += stream.o
|
||||
|
||||
|
||||
281
block/backup-top.c
Normal file
281
block/backup-top.c
Normal file
@ -0,0 +1,281 @@
|
||||
/*
|
||||
* backup-top filter driver
|
||||
*
|
||||
* The driver performs Copy-Before-Write (CBW) operation: it is injected above
|
||||
* some node, and before each write it copies _old_ data to the target node.
|
||||
*
|
||||
* Copyright (c) 2018-2019 Virtuozzo International GmbH.
|
||||
*
|
||||
* Author:
|
||||
* Sementsov-Ogievskiy Vladimir <vsementsov@virtuozzo.com>
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify
|
||||
* it under the terms of the GNU General Public License as published by
|
||||
* the Free Software Foundation; either version 2 of the License, or
|
||||
* (at your option) any later version.
|
||||
*
|
||||
* This program is distributed in the hope that it will be useful,
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
* GNU General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU General Public License
|
||||
* along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
||||
|
||||
#include "qemu/osdep.h"
|
||||
|
||||
#include "sysemu/block-backend.h"
|
||||
#include "qemu/cutils.h"
|
||||
#include "qapi/error.h"
|
||||
#include "block/block_int.h"
|
||||
#include "block/qdict.h"
|
||||
#include "block/block-copy.h"
|
||||
|
||||
#include "block/backup-top.h"
|
||||
|
||||
typedef struct BDRVBackupTopState {
|
||||
BlockCopyState *bcs;
|
||||
BdrvChild *target;
|
||||
bool active;
|
||||
} BDRVBackupTopState;
|
||||
|
||||
static coroutine_fn int backup_top_co_preadv(
|
||||
BlockDriverState *bs, uint64_t offset, uint64_t bytes,
|
||||
QEMUIOVector *qiov, int flags)
|
||||
{
|
||||
return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
|
||||
}
|
||||
|
||||
static coroutine_fn int backup_top_cbw(BlockDriverState *bs, uint64_t offset,
|
||||
uint64_t bytes)
|
||||
{
|
||||
/*
|
||||
* Here we'd like to use block_copy(), but block-copy need to be moved to
|
||||
* use BdrvChildren to correctly use it in backup-top filter. It's a TODO.
|
||||
*/
|
||||
|
||||
abort();
|
||||
}
|
||||
|
||||
static int coroutine_fn backup_top_co_pdiscard(BlockDriverState *bs,
|
||||
int64_t offset, int bytes)
|
||||
{
|
||||
int ret = backup_top_cbw(bs, offset, bytes);
|
||||
if (ret < 0) {
|
||||
return ret;
|
||||
}
|
||||
|
||||
return bdrv_co_pdiscard(bs->backing, offset, bytes);
|
||||
}
|
||||
|
||||
static int coroutine_fn backup_top_co_pwrite_zeroes(BlockDriverState *bs,
|
||||
int64_t offset, int bytes, BdrvRequestFlags flags)
|
||||
{
|
||||
int ret = backup_top_cbw(bs, offset, bytes);
|
||||
if (ret < 0) {
|
||||
return ret;
|
||||
}
|
||||
|
||||
return bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags);
|
||||
}
|
||||
|
||||
static coroutine_fn int backup_top_co_pwritev(BlockDriverState *bs,
|
||||
uint64_t offset,
|
||||
uint64_t bytes,
|
||||
QEMUIOVector *qiov, int flags)
|
||||
{
|
||||
if (!(flags & BDRV_REQ_WRITE_UNCHANGED)) {
|
||||
int ret = backup_top_cbw(bs, offset, bytes);
|
||||
if (ret < 0) {
|
||||
return ret;
|
||||
}
|
||||
}
|
||||
|
||||
return bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags);
|
||||
}
|
||||
|
||||
static int coroutine_fn backup_top_co_flush(BlockDriverState *bs)
|
||||
{
|
||||
if (!bs->backing) {
|
||||
return 0;
|
||||
}
|
||||
|
||||
return bdrv_co_flush(bs->backing->bs);
|
||||
}
|
||||
|
||||
static void backup_top_refresh_filename(BlockDriverState *bs)
|
||||
{
|
||||
if (bs->backing == NULL) {
|
||||
/*
|
||||
* we can be here after failed bdrv_attach_child in
|
||||
* bdrv_set_backing_hd
|
||||
*/
|
||||
return;
|
||||
}
|
||||
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
|
||||
bs->backing->bs->filename);
|
||||
}
|
||||
|
||||
static void backup_top_child_perm(BlockDriverState *bs, BdrvChild *c,
|
||||
const BdrvChildRole *role,
|
||||
BlockReopenQueue *reopen_queue,
|
||||
uint64_t perm, uint64_t shared,
|
||||
uint64_t *nperm, uint64_t *nshared)
|
||||
{
|
||||
BDRVBackupTopState *s = bs->opaque;
|
||||
|
||||
if (!s->active) {
|
||||
/*
|
||||
* The filter node may be in process of bdrv_append(), which firstly do
|
||||
* bdrv_set_backing_hd() and then bdrv_replace_node(). This means that
|
||||
* we can't unshare BLK_PERM_WRITE during bdrv_append() operation. So,
|
||||
* let's require nothing during bdrv_append() and refresh permissions
|
||||
* after it (see bdrv_backup_top_append()).
|
||||
*/
|
||||
*nperm = 0;
|
||||
*nshared = BLK_PERM_ALL;
|
||||
return;
|
||||
}
|
||||
|
||||
if (role == &child_file) {
|
||||
/*
|
||||
* Target child
|
||||
*
|
||||
* Share write to target (child_file), to not interfere
|
||||
* with guest writes to its disk which may be in target backing chain.
|
||||
*/
|
||||
*nshared = BLK_PERM_ALL;
|
||||
*nperm = BLK_PERM_WRITE;
|
||||
} else {
|
||||
/* Source child */
|
||||
bdrv_filter_default_perms(bs, c, role, reopen_queue, perm, shared,
|
||||
nperm, nshared);
|
||||
|
||||
if (perm & BLK_PERM_WRITE) {
|
||||
*nperm = *nperm | BLK_PERM_CONSISTENT_READ;
|
||||
}
|
||||
*nshared &= ~BLK_PERM_WRITE;
|
||||
}
|
||||
}
|
||||
|
||||
BlockDriver bdrv_backup_top_filter = {
|
||||
.format_name = "backup-top",
|
||||
.instance_size = sizeof(BDRVBackupTopState),
|
||||
|
||||
.bdrv_co_preadv = backup_top_co_preadv,
|
||||
.bdrv_co_pwritev = backup_top_co_pwritev,
|
||||
.bdrv_co_pwrite_zeroes = backup_top_co_pwrite_zeroes,
|
||||
.bdrv_co_pdiscard = backup_top_co_pdiscard,
|
||||
.bdrv_co_flush = backup_top_co_flush,
|
||||
|
||||
.bdrv_co_block_status = bdrv_co_block_status_from_backing,
|
||||
|
||||
.bdrv_refresh_filename = backup_top_refresh_filename,
|
||||
|
||||
.bdrv_child_perm = backup_top_child_perm,
|
||||
|
||||
.is_filter = true,
|
||||
};
|
||||
|
||||
BlockDriverState *bdrv_backup_top_append(BlockDriverState *source,
|
||||
BlockDriverState *target,
|
||||
const char *filter_node_name,
|
||||
uint64_t cluster_size,
|
||||
BdrvRequestFlags write_flags,
|
||||
BlockCopyState **bcs,
|
||||
Error **errp)
|
||||
{
|
||||
Error *local_err = NULL;
|
||||
BDRVBackupTopState *state;
|
||||
BlockDriverState *top = bdrv_new_open_driver(&bdrv_backup_top_filter,
|
||||
filter_node_name,
|
||||
BDRV_O_RDWR, errp);
|
||||
|
||||
if (!top) {
|
||||
return NULL;
|
||||
}
|
||||
|
||||
top->total_sectors = source->total_sectors;
|
||||
top->opaque = state = g_new0(BDRVBackupTopState, 1);
|
||||
|
||||
bdrv_ref(target);
|
||||
state->target = bdrv_attach_child(top, target, "target", &child_file, errp);
|
||||
if (!state->target) {
|
||||
bdrv_unref(target);
|
||||
bdrv_unref(top);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
bdrv_drained_begin(source);
|
||||
|
||||
bdrv_ref(top);
|
||||
bdrv_append(top, source, &local_err);
|
||||
if (local_err) {
|
||||
error_prepend(&local_err, "Cannot append backup-top filter: ");
|
||||
goto append_failed;
|
||||
}
|
||||
|
||||
/*
|
||||
* bdrv_append() finished successfully, now we can require permissions
|
||||
* we want.
|
||||
*/
|
||||
state->active = true;
|
||||
bdrv_child_refresh_perms(top, top->backing, &local_err);
|
||||
if (local_err) {
|
||||
error_prepend(&local_err,
|
||||
"Cannot set permissions for backup-top filter: ");
|
||||
goto failed_after_append;
|
||||
}
|
||||
|
||||
/*
|
||||
* TODO: Create block-copy-state here (which will utilize @cluster_size and
|
||||
* @write_flags parameters which are unused now). For this, block-copy
|
||||
* should be refactored to use BdrvChildren.
|
||||
*/
|
||||
state->bcs = NULL;
|
||||
if (!state->bcs) {
|
||||
error_setg(&local_err, "Cannot create block-copy-state");
|
||||
goto failed_after_append;
|
||||
}
|
||||
*bcs = state->bcs;
|
||||
|
||||
bdrv_drained_end(source);
|
||||
|
||||
return top;
|
||||
|
||||
failed_after_append:
|
||||
state->active = false;
|
||||
bdrv_backup_top_drop(top);
|
||||
|
||||
append_failed:
|
||||
bdrv_drained_end(source);
|
||||
bdrv_unref_child(top, state->target);
|
||||
bdrv_unref(top);
|
||||
error_propagate(errp, local_err);
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
void bdrv_backup_top_drop(BlockDriverState *bs)
|
||||
{
|
||||
BDRVBackupTopState *s = bs->opaque;
|
||||
AioContext *aio_context = bdrv_get_aio_context(bs);
|
||||
|
||||
block_copy_state_free(s->bcs);
|
||||
|
||||
aio_context_acquire(aio_context);
|
||||
|
||||
bdrv_drained_begin(bs);
|
||||
|
||||
s->active = false;
|
||||
bdrv_child_refresh_perms(bs, bs->backing, &error_abort);
|
||||
bdrv_replace_node(bs, backing_bs(bs), &error_abort);
|
||||
bdrv_set_backing_hd(bs, NULL, &error_abort);
|
||||
|
||||
bdrv_drained_end(bs);
|
||||
|
||||
bdrv_unref(bs);
|
||||
|
||||
aio_context_release(aio_context);
|
||||
}
|
||||
41
block/backup-top.h
Normal file
41
block/backup-top.h
Normal file
@ -0,0 +1,41 @@
|
||||
/*
|
||||
* backup-top filter driver
|
||||
*
|
||||
* The driver performs Copy-Before-Write (CBW) operation: it is injected above
|
||||
* some node, and before each write it copies _old_ data to the target node.
|
||||
*
|
||||
* Copyright (c) 2018-2019 Virtuozzo International GmbH.
|
||||
*
|
||||
* Author:
|
||||
* Sementsov-Ogievskiy Vladimir <vsementsov@virtuozzo.com>
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or modify
|
||||
* it under the terms of the GNU General Public License as published by
|
||||
* the Free Software Foundation; either version 2 of the License, or
|
||||
* (at your option) any later version.
|
||||
*
|
||||
* This program is distributed in the hope that it will be useful,
|
||||
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||||
* GNU General Public License for more details.
|
||||
*
|
||||
* You should have received a copy of the GNU General Public License
|
||||
* along with this program. If not, see <http://www.gnu.org/licenses/>.
|
||||
*/
|
||||
|
||||
#ifndef BACKUP_TOP_H
|
||||
#define BACKUP_TOP_H
|
||||
|
||||
#include "block/block_int.h"
|
||||
#include "block/block-copy.h"
|
||||
|
||||
BlockDriverState *bdrv_backup_top_append(BlockDriverState *source,
|
||||
BlockDriverState *target,
|
||||
const char *filter_node_name,
|
||||
uint64_t cluster_size,
|
||||
BdrvRequestFlags write_flags,
|
||||
BlockCopyState **bcs,
|
||||
Error **errp);
|
||||
void bdrv_backup_top_drop(BlockDriverState *bs);
|
||||
|
||||
#endif /* BACKUP_TOP_H */
|
||||
Loading…
Reference in New Issue
Block a user