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/*
* snapshot_access block driver
*
* Copyright (c) 2022 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 "block/block_int.h"
static int coroutine_fn GRAPH_RDLOCK
snapshot_access_co_preadv_part(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
if (flags) {
return -ENOTSUP;
}
return bdrv_co_preadv_snapshot(bs->file, offset, bytes, qiov, qiov_offset);
}
static int coroutine_fn GRAPH_RDLOCK
snapshot_access_co_block_status(BlockDriverState *bs,
bool want_zero, int64_t offset,
int64_t bytes, int64_t *pnum,
int64_t *map, BlockDriverState **file)
{
return bdrv_co_snapshot_block_status(bs->file->bs, want_zero, offset,
bytes, pnum, map, file);
}
static int coroutine_fn GRAPH_RDLOCK
snapshot_access_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
{
return bdrv_co_pdiscard_snapshot(bs->file->bs, offset, bytes);
}
static int coroutine_fn
snapshot_access_co_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int64_t bytes,
BdrvRequestFlags flags)
{
return -ENOTSUP;
}
static coroutine_fn int
snapshot_access_co_pwritev_part(BlockDriverState *bs,
int64_t offset, int64_t bytes,
QEMUIOVector *qiov, size_t qiov_offset,
BdrvRequestFlags flags)
{
return -ENOTSUP;
}
static void GRAPH_RDLOCK snapshot_access_refresh_filename(BlockDriverState *bs)
{
pstrcpy(bs->exact_filename, sizeof(bs->exact_filename),
bs->file->bs->filename);
}
static int snapshot_access_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
BDRV_CHILD_DATA | BDRV_CHILD_PRIMARY,
false, errp);
GRAPH_RDLOCK_GUARD_MAINLOOP();
if (!bs->file) {
return -EINVAL;
}
bs->total_sectors = bs->file->bs->total_sectors;
return 0;
}
static void snapshot_access_child_perm(BlockDriverState *bs, BdrvChild *c,
BdrvChildRole role,
BlockReopenQueue *reopen_queue,
uint64_t perm, uint64_t shared,
uint64_t *nperm, uint64_t *nshared)
{
/*
* Currently, we don't need any permissions. If bs->file provides
* snapshot-access API, we can use it.
*/
*nperm = 0;
*nshared = BLK_PERM_ALL;
}
static BlockDriver bdrv_snapshot_access_drv = {
.format_name = "snapshot-access",
.bdrv_open = snapshot_access_open,
.bdrv_co_preadv_part = snapshot_access_co_preadv_part,
.bdrv_co_pwritev_part = snapshot_access_co_pwritev_part,
.bdrv_co_pwrite_zeroes = snapshot_access_co_pwrite_zeroes,
.bdrv_co_pdiscard = snapshot_access_co_pdiscard,
.bdrv_co_block_status = snapshot_access_co_block_status,
.bdrv_refresh_filename = snapshot_access_refresh_filename,
.bdrv_child_perm = snapshot_access_child_perm,
};
static void snapshot_access_init(void)
{
bdrv_register(&bdrv_snapshot_access_drv);
}
block_init(snapshot_access_init);
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