diff options
| -rw-r--r-- | MAINTAINERS | 1 | ||||
| -rw-r--r-- | block/meson.build | 1 | ||||
| -rw-r--r-- | block/snapshot-access.c | 132 | ||||
| -rw-r--r-- | include/block/block_int-common.h | 6 | ||||
| -rw-r--r-- | qapi/block-core.json | 4 |
5 files changed, 143 insertions, 1 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 101eb50619..4f0cc1e448 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -2520,6 +2520,7 @@ F: block/reqlist.c F: include/block/reqlist.h F: block/copy-before-write.h F: block/copy-before-write.c +F: block/snapshot-access.c F: include/block/aio_task.h F: block/aio_task.c F: util/qemu-co-shared-resource.c diff --git a/block/meson.build b/block/meson.build index 553b8eddbc..0b2a60c99b 100644 --- a/block/meson.build +++ b/block/meson.build @@ -34,6 +34,7 @@ block_ss.add(files( 'raw-format.c', 'reqlist.c', 'snapshot.c', + 'snapshot-access.c', 'throttle-groups.c', 'throttle.c', 'vhdx-endian.c', diff --git a/block/snapshot-access.c b/block/snapshot-access.c new file mode 100644 index 0000000000..77b87c1946 --- /dev/null +++ b/block/snapshot-access.c @@ -0,0 +1,132 @@ +/* + * 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 coroutine_fn int +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 +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 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 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) +{ + bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds, + BDRV_CHILD_DATA | BDRV_CHILD_PRIMARY, + false, errp); + 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; +} + +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); diff --git a/include/block/block_int-common.h b/include/block/block_int-common.h index 4ba04d0cc6..8947abab76 100644 --- a/include/block/block_int-common.h +++ b/include/block/block_int-common.h @@ -606,6 +606,12 @@ struct BlockDriver { * in generic block-layer: no serializing, no alignment, no tracked * requests. So, block-driver that realizes these APIs is fully responsible * for synchronization between snapshot-access API and normal IO requests. + * + * TODO: To be able to support qcow2's internal snapshots, this API will + * need to be extended to: + * - be able to select a specific snapshot + * - receive the snapshot's actual length (which may differ from bs's + * length) */ int coroutine_fn (*bdrv_co_preadv_snapshot)(BlockDriverState *bs, int64_t offset, int64_t bytes, QEMUIOVector *qiov, size_t qiov_offset); diff --git a/qapi/block-core.json b/qapi/block-core.json index ffb7aea2a5..f13b5ff942 100644 --- a/qapi/block-core.json +++ b/qapi/block-core.json @@ -2914,13 +2914,14 @@ # @blkreplay: Since 4.2 # @compress: Since 5.0 # @copy-before-write: Since 6.2 +# @snapshot-access: Since 7.0 # # Since: 2.9 ## { 'enum': 'BlockdevDriver', 'data': [ 'blkdebug', 'blklogwrites', 'blkreplay', 'blkverify', 'bochs', 'cloop', 'compress', 'copy-before-write', 'copy-on-read', 'dmg', - 'file', 'ftp', 'ftps', 'gluster', + 'file', 'snapshot-access', 'ftp', 'ftps', 'gluster', {'name': 'host_cdrom', 'if': 'HAVE_HOST_BLOCK_DEVICE' }, {'name': 'host_device', 'if': 'HAVE_HOST_BLOCK_DEVICE' }, 'http', 'https', 'iscsi', @@ -4267,6 +4268,7 @@ 'rbd': 'BlockdevOptionsRbd', 'replication': { 'type': 'BlockdevOptionsReplication', 'if': 'CONFIG_REPLICATION' }, + 'snapshot-access': 'BlockdevOptionsGenericFormat', 'ssh': 'BlockdevOptionsSsh', 'throttle': 'BlockdevOptionsThrottle', 'vdi': 'BlockdevOptionsGenericFormat', |