diff options
| -rw-r--r-- | block/copy-on-read.c | 56 | ||||
| -rw-r--r-- | block/copy-on-read.h | 32 |
2 files changed, 88 insertions, 0 deletions
diff --git a/block/copy-on-read.c b/block/copy-on-read.c index cb03e0f..618c4c4 100644 --- a/block/copy-on-read.c +++ b/block/copy-on-read.c @@ -23,11 +23,20 @@ #include "qemu/osdep.h" #include "block/block_int.h" #include "qemu/module.h" +#include "qapi/error.h" +#include "block/copy-on-read.h" + + +typedef struct BDRVStateCOR { + bool active; +} BDRVStateCOR; static int cor_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { + BDRVStateCOR *state = bs->opaque; + bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds, BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY, false, errp); @@ -42,6 +51,13 @@ static int cor_open(BlockDriverState *bs, QDict *options, int flags, ((BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP | BDRV_REQ_NO_FALLBACK) & bs->file->bs->supported_zero_flags); + state->active = true; + + /* + * We don't need to call bdrv_child_refresh_perms() now as the permissions + * will be updated later when the filter node gets its parent. + */ + return 0; } @@ -57,6 +73,17 @@ static void cor_child_perm(BlockDriverState *bs, BdrvChild *c, uint64_t perm, uint64_t shared, uint64_t *nperm, uint64_t *nshared) { + BDRVStateCOR *s = bs->opaque; + + if (!s->active) { + /* + * While the filter is being removed + */ + *nperm = 0; + *nshared = BLK_PERM_ALL; + return; + } + *nperm = perm & PERM_PASSTHROUGH; *nshared = (shared & PERM_PASSTHROUGH) | PERM_UNCHANGED; @@ -135,6 +162,7 @@ static void cor_lock_medium(BlockDriverState *bs, bool locked) static BlockDriver bdrv_copy_on_read = { .format_name = "copy-on-read", + .instance_size = sizeof(BDRVStateCOR), .bdrv_open = cor_open, .bdrv_child_perm = cor_child_perm, @@ -154,6 +182,34 @@ static BlockDriver bdrv_copy_on_read = { .is_filter = true, }; + +void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs) +{ + BdrvChild *child; + BlockDriverState *bs; + BDRVStateCOR *s = cor_filter_bs->opaque; + + child = bdrv_filter_child(cor_filter_bs); + if (!child) { + return; + } + bs = child->bs; + + /* Retain the BDS until we complete the graph change. */ + bdrv_ref(bs); + /* Hold a guest back from writing while permissions are being reset. */ + bdrv_drained_begin(bs); + /* Drop permissions before the graph change. */ + s->active = false; + bdrv_child_refresh_perms(cor_filter_bs, child, &error_abort); + bdrv_replace_node(cor_filter_bs, bs, &error_abort); + + bdrv_drained_end(bs); + bdrv_unref(bs); + bdrv_unref(cor_filter_bs); +} + + static void bdrv_copy_on_read_init(void) { bdrv_register(&bdrv_copy_on_read); diff --git a/block/copy-on-read.h b/block/copy-on-read.h new file mode 100644 index 0000000..7bf405d --- /dev/null +++ b/block/copy-on-read.h @@ -0,0 +1,32 @@ +/* + * Copy-on-read filter block driver + * + * The filter driver performs Copy-On-Read (COR) operations + * + * Copyright (c) 2018-2020 Virtuozzo International GmbH. + * + * Author: + * Andrey Shinkevich <andrey.shinkevich@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 BLOCK_COPY_ON_READ +#define BLOCK_COPY_ON_READ + +#include "block/block_int.h" + +void bdrv_cor_filter_drop(BlockDriverState *cor_filter_bs); + +#endif /* BLOCK_COPY_ON_READ */ |