Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
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>
- Loading branch information
Showing
3 changed files
with
323 additions
and
0 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -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); | ||
} |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -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 */ |