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qemu/include/block/write-threshold.h
Markus Armbruster ec150c7e09 include: Make headers more self-contained
Back in 2016, we discussed[1] rules for headers, and these were
generally liked:

1. Have a carefully curated header that's included everywhere first.  We
   got that already thanks to Peter: osdep.h.

2. Headers should normally include everything they need beyond osdep.h.
   If exceptions are needed for some reason, they must be documented in
   the header.  If all that's needed from a header is typedefs, put
   those into qemu/typedefs.h instead of including the header.

3. Cyclic inclusion is forbidden.

This patch gets include/ closer to obeying 2.

It's actually extracted from my "[RFC] Baby steps towards saner
headers" series[2], which demonstrates a possible path towards
checking 2 automatically.  It passes the RFC test there.

[1] Message-ID: <87h9g8j57d.fsf@blackfin.pond.sub.org>
    https://lists.nongnu.org/archive/html/qemu-devel/2016-03/msg03345.html
[2] Message-Id: <20190711122827.18970-1-armbru@redhat.com>
    https://lists.nongnu.org/archive/html/qemu-devel/2019-07/msg02715.html

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20190812052359.30071-2-armbru@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
2019-08-16 13:31:51 +02:00

63 lines
1.6 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);
#endif