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 #ifndef BLOCK_WRITE_THRESHOLD_H 13 #define BLOCK_WRITE_THRESHOLD_H 14 15 #include "qemu-common.h" 16 17 /* 18 * bdrv_write_threshold_set: 19 * 20 * Set the write threshold for block devices, in bytes. 21 * Notify when a write exceeds the threshold, meaning the device 22 * is becoming full, so it can be transparently resized. 23 * To be used with thin-provisioned block devices. 24 * 25 * Use threshold_bytes == 0 to disable. 26 */ 27 void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes); 28 29 /* 30 * bdrv_write_threshold_get 31 * 32 * Get the configured write threshold, in bytes. 33 * Zero means no threshold configured. 34 */ 35 uint64_t bdrv_write_threshold_get(const BlockDriverState *bs); 36 37 /* 38 * bdrv_write_threshold_is_set 39 * 40 * Tell if a write threshold is set for a given BDS. 41 */ 42 bool bdrv_write_threshold_is_set(const BlockDriverState *bs); 43 44 /* 45 * bdrv_write_threshold_exceeded 46 * 47 * Return the extent of a write request that exceeded the threshold, 48 * or zero if the request is below the threshold. 49 * Return zero also if the threshold was not set. 50 * 51 * NOTE: here we assume the following holds for each request this code 52 * deals with: 53 * 54 * assert((req->offset + req->bytes) <= UINT64_MAX) 55 * 56 * Please not there is *not* an actual C assert(). 57 */ 58 uint64_t bdrv_write_threshold_exceeded(const BlockDriverState *bs, 59 const BdrvTrackedRequest *req); 60 61 #endif 62