diff --git a/block/Makefile.objs b/block/Makefile.objs index f06f1fa1ac9c..e394fe0b6ca2 100644 --- a/block/Makefile.objs +++ b/block/Makefile.objs @@ -42,6 +42,7 @@ block-obj-y += block-copy.o block-obj-y += crypto.o block-obj-y += aio_task.o +block-obj-y += backup-top.o common-obj-y += stream.o diff --git a/block/backup-top.c b/block/backup-top.c new file mode 100644 index 000000000000..75a315744d24 --- /dev/null +++ b/block/backup-top.c @@ -0,0 +1,281 @@ +/* + * backup-top filter driver + * + * The driver performs Copy-Before-Write (CBW) operation: it is injected above + * some node, and before each write it copies _old_ data to the target node. + * + * Copyright (c) 2018-2019 Virtuozzo International GmbH. + * + * Author: + * Sementsov-Ogievskiy Vladimir + * + * 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 . + */ + +#include "qemu/osdep.h" + +#include "sysemu/block-backend.h" +#include "qemu/cutils.h" +#include "qapi/error.h" +#include "block/block_int.h" +#include "block/qdict.h" +#include "block/block-copy.h" + +#include "block/backup-top.h" + +typedef struct BDRVBackupTopState { + BlockCopyState *bcs; + BdrvChild *target; + bool active; +} BDRVBackupTopState; + +static coroutine_fn int backup_top_co_preadv( + BlockDriverState *bs, uint64_t offset, uint64_t bytes, + QEMUIOVector *qiov, int flags) +{ + return bdrv_co_preadv(bs->backing, offset, bytes, qiov, flags); +} + +static coroutine_fn int backup_top_cbw(BlockDriverState *bs, uint64_t offset, + uint64_t bytes) +{ + /* + * Here we'd like to use block_copy(), but block-copy need to be moved to + * use BdrvChildren to correctly use it in backup-top filter. It's a TODO. + */ + + abort(); +} + +static int coroutine_fn backup_top_co_pdiscard(BlockDriverState *bs, + int64_t offset, int bytes) +{ + int ret = backup_top_cbw(bs, offset, bytes); + if (ret < 0) { + return ret; + } + + return bdrv_co_pdiscard(bs->backing, offset, bytes); +} + +static int coroutine_fn backup_top_co_pwrite_zeroes(BlockDriverState *bs, + int64_t offset, int bytes, BdrvRequestFlags flags) +{ + int ret = backup_top_cbw(bs, offset, bytes); + if (ret < 0) { + return ret; + } + + return bdrv_co_pwrite_zeroes(bs->backing, offset, bytes, flags); +} + +static coroutine_fn int backup_top_co_pwritev(BlockDriverState *bs, + uint64_t offset, + uint64_t bytes, + QEMUIOVector *qiov, int flags) +{ + if (!(flags & BDRV_REQ_WRITE_UNCHANGED)) { + int ret = backup_top_cbw(bs, offset, bytes); + if (ret < 0) { + return ret; + } + } + + return bdrv_co_pwritev(bs->backing, offset, bytes, qiov, flags); +} + +static int coroutine_fn backup_top_co_flush(BlockDriverState *bs) +{ + if (!bs->backing) { + return 0; + } + + return bdrv_co_flush(bs->backing->bs); +} + +static void backup_top_refresh_filename(BlockDriverState *bs) +{ + if (bs->backing == NULL) { + /* + * we can be here after failed bdrv_attach_child in + * bdrv_set_backing_hd + */ + return; + } + pstrcpy(bs->exact_filename, sizeof(bs->exact_filename), + bs->backing->bs->filename); +} + +static void backup_top_child_perm(BlockDriverState *bs, BdrvChild *c, + const BdrvChildRole *role, + BlockReopenQueue *reopen_queue, + uint64_t perm, uint64_t shared, + uint64_t *nperm, uint64_t *nshared) +{ + BDRVBackupTopState *s = bs->opaque; + + if (!s->active) { + /* + * The filter node may be in process of bdrv_append(), which firstly do + * bdrv_set_backing_hd() and then bdrv_replace_node(). This means that + * we can't unshare BLK_PERM_WRITE during bdrv_append() operation. So, + * let's require nothing during bdrv_append() and refresh permissions + * after it (see bdrv_backup_top_append()). + */ + *nperm = 0; + *nshared = BLK_PERM_ALL; + return; + } + + if (role == &child_file) { + /* + * Target child + * + * Share write to target (child_file), to not interfere + * with guest writes to its disk which may be in target backing chain. + */ + *nshared = BLK_PERM_ALL; + *nperm = BLK_PERM_WRITE; + } else { + /* Source child */ + bdrv_filter_default_perms(bs, c, role, reopen_queue, perm, shared, + nperm, nshared); + + if (perm & BLK_PERM_WRITE) { + *nperm = *nperm | BLK_PERM_CONSISTENT_READ; + } + *nshared &= ~BLK_PERM_WRITE; + } +} + +BlockDriver bdrv_backup_top_filter = { + .format_name = "backup-top", + .instance_size = sizeof(BDRVBackupTopState), + + .bdrv_co_preadv = backup_top_co_preadv, + .bdrv_co_pwritev = backup_top_co_pwritev, + .bdrv_co_pwrite_zeroes = backup_top_co_pwrite_zeroes, + .bdrv_co_pdiscard = backup_top_co_pdiscard, + .bdrv_co_flush = backup_top_co_flush, + + .bdrv_co_block_status = bdrv_co_block_status_from_backing, + + .bdrv_refresh_filename = backup_top_refresh_filename, + + .bdrv_child_perm = backup_top_child_perm, + + .is_filter = true, +}; + +BlockDriverState *bdrv_backup_top_append(BlockDriverState *source, + BlockDriverState *target, + const char *filter_node_name, + uint64_t cluster_size, + BdrvRequestFlags write_flags, + BlockCopyState **bcs, + Error **errp) +{ + Error *local_err = NULL; + BDRVBackupTopState *state; + BlockDriverState *top = bdrv_new_open_driver(&bdrv_backup_top_filter, + filter_node_name, + BDRV_O_RDWR, errp); + + if (!top) { + return NULL; + } + + top->total_sectors = source->total_sectors; + top->opaque = state = g_new0(BDRVBackupTopState, 1); + + bdrv_ref(target); + state->target = bdrv_attach_child(top, target, "target", &child_file, errp); + if (!state->target) { + bdrv_unref(target); + bdrv_unref(top); + return NULL; + } + + bdrv_drained_begin(source); + + bdrv_ref(top); + bdrv_append(top, source, &local_err); + if (local_err) { + error_prepend(&local_err, "Cannot append backup-top filter: "); + goto append_failed; + } + + /* + * bdrv_append() finished successfully, now we can require permissions + * we want. + */ + state->active = true; + bdrv_child_refresh_perms(top, top->backing, &local_err); + if (local_err) { + error_prepend(&local_err, + "Cannot set permissions for backup-top filter: "); + goto failed_after_append; + } + + /* + * TODO: Create block-copy-state here (which will utilize @cluster_size and + * @write_flags parameters which are unused now). For this, block-copy + * should be refactored to use BdrvChildren. + */ + state->bcs = NULL; + if (!state->bcs) { + error_setg(&local_err, "Cannot create block-copy-state"); + goto failed_after_append; + } + *bcs = state->bcs; + + bdrv_drained_end(source); + + return top; + +failed_after_append: + state->active = false; + bdrv_backup_top_drop(top); + +append_failed: + bdrv_drained_end(source); + bdrv_unref_child(top, state->target); + bdrv_unref(top); + error_propagate(errp, local_err); + + return NULL; +} + +void bdrv_backup_top_drop(BlockDriverState *bs) +{ + BDRVBackupTopState *s = bs->opaque; + AioContext *aio_context = bdrv_get_aio_context(bs); + + block_copy_state_free(s->bcs); + + aio_context_acquire(aio_context); + + bdrv_drained_begin(bs); + + s->active = false; + bdrv_child_refresh_perms(bs, bs->backing, &error_abort); + bdrv_replace_node(bs, backing_bs(bs), &error_abort); + bdrv_set_backing_hd(bs, NULL, &error_abort); + + bdrv_drained_end(bs); + + bdrv_unref(bs); + + aio_context_release(aio_context); +} diff --git a/block/backup-top.h b/block/backup-top.h new file mode 100644 index 000000000000..e5cabfa19709 --- /dev/null +++ b/block/backup-top.h @@ -0,0 +1,41 @@ +/* + * backup-top filter driver + * + * The driver performs Copy-Before-Write (CBW) operation: it is injected above + * some node, and before each write it copies _old_ data to the target node. + * + * Copyright (c) 2018-2019 Virtuozzo International GmbH. + * + * Author: + * Sementsov-Ogievskiy Vladimir + * + * 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 . + */ + +#ifndef BACKUP_TOP_H +#define BACKUP_TOP_H + +#include "block/block_int.h" +#include "block/block-copy.h" + +BlockDriverState *bdrv_backup_top_append(BlockDriverState *source, + BlockDriverState *target, + const char *filter_node_name, + uint64_t cluster_size, + BdrvRequestFlags write_flags, + BlockCopyState **bcs, + Error **errp); +void bdrv_backup_top_drop(BlockDriverState *bs); + +#endif /* BACKUP_TOP_H */