Experiments show, that copy_range is not always making things faster. So, to make experimentation simpler, let's add a parameter. Some more perf parameters will be added soon, so here is a new struct. For now, add new backup qmp parameter with x- prefix for the following reasons: - We are going to add more performance parameters, some will be related to the whole block-copy process, some only to background copying in backup (ignored for copy-before-write operations). - On the other hand, we are going to use block-copy interface in other block jobs, which will need performance options as well.. And it should be the same structure or at least somehow related. So, there are too much unclean things about how the interface and now we need the new options mostly for testing. Let's keep them experimental for a while. In do_backup_common() new x-perf parameter handled in a way to make further options addition simpler. We add use-copy-range with default=true, and we'll change the default in further patch, after moving backup to use block-copy. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Max Reitz <mreitz@redhat.com> Message-Id: <20210116214705.822267-2-vsementsov@virtuozzo.com> [mreitz: s/5\.2/6.0/] Signed-off-by: Max Reitz <mreitz@redhat.com>
291 lines
8.7 KiB
C
291 lines
8.7 KiB
C
/*
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* backup-top filter driver
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*
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* The driver performs Copy-Before-Write (CBW) operation: it is injected above
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* some node, and before each write it copies _old_ data to the target node.
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*
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* Copyright (c) 2018-2019 Virtuozzo International GmbH.
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*
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* Author:
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* Sementsov-Ogievskiy Vladimir <vsementsov@virtuozzo.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "qemu/osdep.h"
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#include "sysemu/block-backend.h"
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#include "qemu/cutils.h"
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#include "qapi/error.h"
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#include "block/block_int.h"
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#include "block/qdict.h"
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#include "block/block-copy.h"
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#include "block/backup-top.h"
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typedef struct BDRVBackupTopState {
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BlockCopyState *bcs;
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BdrvChild *target;
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bool active;
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int64_t cluster_size;
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} BDRVBackupTopState;
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static coroutine_fn int backup_top_co_preadv(
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BlockDriverState *bs, uint64_t offset, uint64_t bytes,
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QEMUIOVector *qiov, int flags)
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{
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return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags);
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}
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static coroutine_fn int backup_top_cbw(BlockDriverState *bs, uint64_t offset,
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uint64_t bytes, BdrvRequestFlags flags)
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{
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BDRVBackupTopState *s = bs->opaque;
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uint64_t off, end;
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if (flags & BDRV_REQ_WRITE_UNCHANGED) {
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return 0;
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}
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off = QEMU_ALIGN_DOWN(offset, s->cluster_size);
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end = QEMU_ALIGN_UP(offset + bytes, s->cluster_size);
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return block_copy(s->bcs, off, end - off, NULL);
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}
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static int coroutine_fn backup_top_co_pdiscard(BlockDriverState *bs,
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int64_t offset, int bytes)
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{
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int ret = backup_top_cbw(bs, offset, bytes, 0);
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if (ret < 0) {
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return ret;
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}
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return bdrv_co_pdiscard(bs->backing, offset, bytes);
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}
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static int coroutine_fn backup_top_co_pwrite_zeroes(BlockDriverState *bs,
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int64_t offset, int bytes, BdrvRequestFlags flags)
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{
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int ret = backup_top_cbw(bs, offset, bytes, flags);
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if (ret < 0) {
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return ret;
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}
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return bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags);
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}
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static coroutine_fn int backup_top_co_pwritev(BlockDriverState *bs,
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uint64_t offset,
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uint64_t bytes,
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QEMUIOVector *qiov, int flags)
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{
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int ret = backup_top_cbw(bs, offset, bytes, flags);
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if (ret < 0) {
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return ret;
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}
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return bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags);
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}
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static int coroutine_fn backup_top_co_flush(BlockDriverState *bs)
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{
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if (!bs->backing) {
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return 0;
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}
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return bdrv_co_flush(bs->backing->bs);
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}
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static void backup_top_refresh_filename(BlockDriverState *bs)
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{
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if (bs->backing == NULL) {
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/*
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* we can be here after failed bdrv_attach_child in
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* bdrv_set_backing_hd
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*/
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return;
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}
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pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
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bs->backing->bs->filename);
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}
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static void backup_top_child_perm(BlockDriverState *bs, BdrvChild *c,
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BdrvChildRole role,
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BlockReopenQueue *reopen_queue,
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uint64_t perm, uint64_t shared,
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uint64_t *nperm, uint64_t *nshared)
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{
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BDRVBackupTopState *s = bs->opaque;
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if (!s->active) {
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/*
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* The filter node may be in process of bdrv_append(), which firstly do
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* bdrv_set_backing_hd() and then bdrv_replace_node(). This means that
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* we can't unshare BLK_PERM_WRITE during bdrv_append() operation. So,
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* let's require nothing during bdrv_append() and refresh permissions
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* after it (see bdrv_backup_top_append()).
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*/
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*nperm = 0;
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*nshared = BLK_PERM_ALL;
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return;
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}
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if (!(role & BDRV_CHILD_FILTERED)) {
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/*
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* Target child
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*
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* Share write to target (child_file), to not interfere
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* with guest writes to its disk which may be in target backing chain.
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* Can't resize during a backup block job because we check the size
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* only upfront.
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*/
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*nshared = BLK_PERM_ALL & ~BLK_PERM_RESIZE;
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*nperm = BLK_PERM_WRITE;
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} else {
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/* Source child */
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bdrv_default_perms(bs, c, role, reopen_queue,
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perm, shared, nperm, nshared);
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if (perm & BLK_PERM_WRITE) {
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*nperm = *nperm | BLK_PERM_CONSISTENT_READ;
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}
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*nshared &= ~(BLK_PERM_WRITE | BLK_PERM_RESIZE);
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}
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}
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BlockDriver bdrv_backup_top_filter = {
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.format_name = "backup-top",
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.instance_size = sizeof(BDRVBackupTopState),
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.bdrv_co_preadv = backup_top_co_preadv,
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.bdrv_co_pwritev = backup_top_co_pwritev,
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.bdrv_co_pwrite_zeroes = backup_top_co_pwrite_zeroes,
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.bdrv_co_pdiscard = backup_top_co_pdiscard,
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.bdrv_co_flush = backup_top_co_flush,
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.bdrv_refresh_filename = backup_top_refresh_filename,
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.bdrv_child_perm = backup_top_child_perm,
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.is_filter = true,
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};
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BlockDriverState *bdrv_backup_top_append(BlockDriverState *source,
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BlockDriverState *target,
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const char *filter_node_name,
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uint64_t cluster_size,
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BackupPerf *perf,
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BdrvRequestFlags write_flags,
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BlockCopyState **bcs,
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Error **errp)
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{
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Error *local_err = NULL;
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BDRVBackupTopState *state;
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BlockDriverState *top;
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bool appended = false;
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assert(source->total_sectors == target->total_sectors);
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top = bdrv_new_open_driver(&bdrv_backup_top_filter, filter_node_name,
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BDRV_O_RDWR, errp);
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if (!top) {
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return NULL;
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}
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state = top->opaque;
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top->total_sectors = source->total_sectors;
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top->supported_write_flags = BDRV_REQ_WRITE_UNCHANGED |
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(BDRV_REQ_FUA & source->supported_write_flags);
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top->supported_zero_flags = BDRV_REQ_WRITE_UNCHANGED |
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((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) &
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source->supported_zero_flags);
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bdrv_ref(target);
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state->target = bdrv_attach_child(top, target, "target", &child_of_bds,
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BDRV_CHILD_DATA, errp);
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if (!state->target) {
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bdrv_unref(target);
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bdrv_unref(top);
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return NULL;
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}
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bdrv_drained_begin(source);
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bdrv_ref(top);
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bdrv_append(top, source, &local_err);
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if (local_err) {
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error_prepend(&local_err, "Cannot append backup-top filter: ");
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goto fail;
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}
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appended = true;
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/*
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* bdrv_append() finished successfully, now we can require permissions
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* we want.
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*/
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state->active = true;
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bdrv_child_refresh_perms(top, top->backing, &local_err);
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if (local_err) {
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error_prepend(&local_err,
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"Cannot set permissions for backup-top filter: ");
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goto fail;
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}
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state->cluster_size = cluster_size;
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state->bcs = block_copy_state_new(top->backing, state->target,
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cluster_size, perf->use_copy_range,
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write_flags, &local_err);
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if (local_err) {
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error_prepend(&local_err, "Cannot create block-copy-state: ");
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goto fail;
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}
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*bcs = state->bcs;
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bdrv_drained_end(source);
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return top;
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fail:
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if (appended) {
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state->active = false;
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bdrv_backup_top_drop(top);
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} else {
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bdrv_unref(top);
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}
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bdrv_drained_end(source);
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error_propagate(errp, local_err);
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return NULL;
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}
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void bdrv_backup_top_drop(BlockDriverState *bs)
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{
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BDRVBackupTopState *s = bs->opaque;
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bdrv_drained_begin(bs);
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block_copy_state_free(s->bcs);
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s->active = false;
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bdrv_child_refresh_perms(bs, bs->backing, &error_abort);
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bdrv_replace_node(bs, bs->backing->bs, &error_abort);
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bdrv_set_backing_hd(bs, NULL, &error_abort);
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bdrv_drained_end(bs);
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bdrv_unref(bs);
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}
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