[qemu.git] / include / block / write-threshold.h

/*
 * QEMU System Emulator block write threshold notification
 *
 * Copyright Red Hat, Inc. 2014
 *
 * Authors:
 *  Francesco Romani <[email protected]>
 *
 * 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);

#endif
Commit	Line	Data
e2462113 FR	1	/*
	2	* QEMU System Emulator block write threshold notification
	3	*
	4	* Copyright Red Hat, Inc. 2014
	5	*
	6	* Authors:
	7	* Francesco Romani <[email protected]>
	8	*
	9	* This work is licensed under the terms of the GNU LGPL, version 2 or later.
	10	* See the COPYING.LIB file in the top-level directory.
	11	*/
ec150c7e	12
e2462113 FR	13	#ifndef BLOCK_WRITE_THRESHOLD_H
	14	#define BLOCK_WRITE_THRESHOLD_H
	15
ec150c7e	16	#include "block/block_int.h"
e2462113 FR	17
	18	/*
	19	* bdrv_write_threshold_set:
	20	*
	21	* Set the write threshold for block devices, in bytes.
	22	* Notify when a write exceeds the threshold, meaning the device
	23	* is becoming full, so it can be transparently resized.
	24	* To be used with thin-provisioned block devices.
	25	*
	26	* Use threshold_bytes == 0 to disable.
	27	*/
	28	void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes);
	29
	30	/*
	31	* bdrv_write_threshold_get
	32	*
	33	* Get the configured write threshold, in bytes.
	34	* Zero means no threshold configured.
	35	*/
	36	uint64_t bdrv_write_threshold_get(const BlockDriverState *bs);
	37
	38	/*
	39	* bdrv_write_threshold_is_set
	40	*
	41	* Tell if a write threshold is set for a given BDS.
	42	*/
	43	bool bdrv_write_threshold_is_set(const BlockDriverState *bs);
	44
	45	/*
	46	* bdrv_write_threshold_exceeded
	47	*
	48	* Return the extent of a write request that exceeded the threshold,
	49	* or zero if the request is below the threshold.
	50	* Return zero also if the threshold was not set.
	51	*
	52	* NOTE: here we assume the following holds for each request this code
	53	* deals with:
	54	*
	55	* assert((req->offset + req->bytes) <= UINT64_MAX)
	56	*
	57	* Please not there is not an actual C assert().
	58	*/
	59	uint64_t bdrv_write_threshold_exceeded(const BlockDriverState *bs,
	60	const BdrvTrackedRequest *req);
	61
	62	#endif