bdrv_default_perms() can decide which permission profile to use based on the BdrvChildRole, so block drivers do not need to select it explicitly. The blkverify driver now no longer shares the WRITE permission for the image to verify. We thus have to adjust two places in test-block-iothread not to take it. (Note that in theory, blkverify should behave like quorum in this regard and share neither WRITE nor RESIZE for both of its children. In practice, it does not really matter, because blkverify is used only for debugging, so we might as well keep its permissions rather liberal.) Signed-off-by: Max Reitz <mreitz@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20200513110544.176672-30-mreitz@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
292 lines
8.7 KiB
C
292 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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const BdrvChildClass *child_class,
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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, child_class, 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_co_block_status = bdrv_co_block_status_from_backing,
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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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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, 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, backing_bs(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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