qemu/include/block/write-threshold.h
Vladimir Sementsov-Ogievskiy 94783301b8 block/write-threshold: don't use write notifiers
write-notifiers are used only for write-threshold. New code for such
purpose should create filters.

Let's better special-case write-threshold and drop write notifiers at
all. (Actually, write-threshold is special-cased anyway, as the only
user of write-notifiers)

So, create a new direct interface for bdrv_co_write_req_prepare() and
drop all write-notifier related logic from write-threshold.c.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210506090621.11848-2-vsementsov@virtuozzo.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
[mreitz: Adjusted comment as per Eric's suggestion]
Signed-off-by: Max Reitz <mreitz@redhat.com>
2021-05-14 16:14:10 +02:00

72 lines
2 KiB
C

/*
* QEMU System Emulator block write threshold notification
*
* Copyright Red Hat, Inc. 2014
*
* Authors:
* Francesco Romani <fromani@redhat.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*/
#ifndef BLOCK_WRITE_THRESHOLD_H
#define BLOCK_WRITE_THRESHOLD_H
#include "block/block_int.h"
/*
* bdrv_write_threshold_set:
*
* Set the write threshold for block devices, in bytes.
* Notify when a write exceeds the threshold, meaning the device
* is becoming full, so it can be transparently resized.
* To be used with thin-provisioned block devices.
*
* Use threshold_bytes == 0 to disable.
*/
void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes);
/*
* bdrv_write_threshold_get
*
* Get the configured write threshold, in bytes.
* Zero means no threshold configured.
*/
uint64_t bdrv_write_threshold_get(const BlockDriverState *bs);
/*
* bdrv_write_threshold_is_set
*
* Tell if a write threshold is set for a given BDS.
*/
bool bdrv_write_threshold_is_set(const BlockDriverState *bs);
/*
* bdrv_write_threshold_exceeded
*
* Return the extent of a write request that exceeded the threshold,
* or zero if the request is below the threshold.
* Return zero also if the threshold was not set.
*
* NOTE: here we assume the following holds for each request this code
* deals with:
*
* assert((req->offset + req->bytes) <= UINT64_MAX)
*
* Please not there is *not* an actual C assert().
*/
uint64_t bdrv_write_threshold_exceeded(const BlockDriverState *bs,
const BdrvTrackedRequest *req);
/*
* bdrv_write_threshold_check_write
*
* Check whether the specified request exceeds the write threshold.
* If so, send a corresponding event and disable write threshold checking.
*/
void bdrv_write_threshold_check_write(BlockDriverState *bs, int64_t offset,
int64_t bytes);
#endif