include/block/write-threshold.h

   1 /*
   2  * QEMU System Emulator block write threshold notification
   3  *
   4  * Copyright Red Hat, Inc. 2014
   5  *
   6  * Authors:
   7  *  Francesco Romani <fromani@redhat.com>
   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  */
  12
  13 #ifndef BLOCK_WRITE_THRESHOLD_H
  14 #define BLOCK_WRITE_THRESHOLD_H
  15
  16 #include "block/block_int.h"
  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