qemu/include/block/block-copy.h
Vladimir Sementsov-Ogievskiy 0fd05c8d80 qapi: blockdev-backup: add discard-source parameter
Add a parameter that enables discard-after-copy. That is mostly useful
in "push backup with fleecing" scheme, when source is snapshot-access
format driver node, based on copy-before-write filter snapshot-access
API:

[guest]      [snapshot-access] ~~ blockdev-backup ~~> [backup target]
   |            |
   | root       | file
   v            v
[copy-before-write]
   |             |
   | file        | target
   v             v
[active disk]   [temp.img]

In this case discard-after-copy does two things:

 - discard data in temp.img to save disk space
 - avoid further copy-before-write operation in discarded area

Note that we have to declare WRITE permission on source in
copy-before-write filter, for discard to work. Still we can't take it
unconditionally, as it will break normal backup from RO source. So, we
have to add a parameter and pass it thorough bdrv_open flags.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>
Tested-by: Fiona Ebner <f.ebner@proxmox.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20240313152822.626493-5-vsementsov@yandex-team.ru>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
2024-05-28 15:52:15 +03:00

104 lines
3.8 KiB
C

/*
* block_copy API
*
* Copyright (C) 2013 Proxmox Server Solutions
* Copyright (c) 2019 Virtuozzo International GmbH.
*
* Authors:
* Dietmar Maurer (dietmar@proxmox.com)
* Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef BLOCK_COPY_H
#define BLOCK_COPY_H
#include "block/block-common.h"
#include "qemu/progress_meter.h"
/* All APIs are thread-safe */
typedef void (*BlockCopyAsyncCallbackFunc)(void *opaque);
typedef struct BlockCopyState BlockCopyState;
typedef struct BlockCopyCallState BlockCopyCallState;
BlockCopyState *block_copy_state_new(BdrvChild *source, BdrvChild *target,
BlockDriverState *copy_bitmap_bs,
const BdrvDirtyBitmap *bitmap,
bool discard_source,
Error **errp);
/* Function should be called prior any actual copy request */
void block_copy_set_copy_opts(BlockCopyState *s, bool use_copy_range,
bool compress);
void block_copy_set_progress_meter(BlockCopyState *s, ProgressMeter *pm);
void block_copy_state_free(BlockCopyState *s);
void block_copy_reset(BlockCopyState *s, int64_t offset, int64_t bytes);
int64_t coroutine_fn GRAPH_RDLOCK
block_copy_reset_unallocated(BlockCopyState *s, int64_t offset, int64_t *count);
int coroutine_fn block_copy(BlockCopyState *s, int64_t offset, int64_t bytes,
bool ignore_ratelimit, uint64_t timeout_ns,
BlockCopyAsyncCallbackFunc cb,
void *cb_opaque);
/*
* Run block-copy in a coroutine, create corresponding BlockCopyCallState
* object and return pointer to it. Never returns NULL.
*
* Caller is responsible to call block_copy_call_free() to free
* BlockCopyCallState object.
*
* @max_workers means maximum of parallel coroutines to execute sub-requests,
* must be > 0.
*
* @max_chunk means maximum length for one IO operation. Zero means unlimited.
*/
BlockCopyCallState *block_copy_async(BlockCopyState *s,
int64_t offset, int64_t bytes,
int max_workers, int64_t max_chunk,
BlockCopyAsyncCallbackFunc cb,
void *cb_opaque);
/*
* Free finished BlockCopyCallState. Trying to free running
* block-copy will crash.
*/
void block_copy_call_free(BlockCopyCallState *call_state);
/*
* Note, that block-copy call is marked finished prior to calling
* the callback.
*/
bool block_copy_call_finished(BlockCopyCallState *call_state);
bool block_copy_call_succeeded(BlockCopyCallState *call_state);
bool block_copy_call_failed(BlockCopyCallState *call_state);
bool block_copy_call_cancelled(BlockCopyCallState *call_state);
int block_copy_call_status(BlockCopyCallState *call_state, bool *error_is_read);
void block_copy_set_speed(BlockCopyState *s, uint64_t speed);
void block_copy_kick(BlockCopyCallState *call_state);
/*
* Cancel running block-copy call.
*
* Cancel leaves block-copy state valid: dirty bits are correct and you may use
* cancel + <run block_copy with same parameters> to emulate pause/resume.
*
* Note also, that the cancel is async: it only marks block-copy call to be
* cancelled. So, the call may be cancelled (block_copy_call_cancelled() reports
* true) but not yet finished (block_copy_call_finished() reports false).
*/
void block_copy_call_cancel(BlockCopyCallState *call_state);
BdrvDirtyBitmap *block_copy_dirty_bitmap(BlockCopyState *s);
int64_t block_copy_cluster_size(BlockCopyState *s);
void block_copy_set_skip_unallocated(BlockCopyState *s, bool skip);
#endif /* BLOCK_COPY_H */