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 16 #include "qemu/typedefs.h" 17 #include "qemu-common.h" 18 19 /* 20 * bdrv_write_threshold_set: 21 * 22 * Set the write threshold for block devices, in bytes. 23 * Notify when a write exceeds the threshold, meaning the device 24 * is becoming full, so it can be transparently resized. 25 * To be used with thin-provisioned block devices. 26 * 27 * Use threshold_bytes == 0 to disable. 28 */ 29 void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes); 30 31 /* 32 * bdrv_write_threshold_get 33 * 34 * Get the configured write threshold, in bytes. 35 * Zero means no threshold configured. 36 */ 37 uint64_t bdrv_write_threshold_get(const BlockDriverState *bs); 38 39 /* 40 * bdrv_write_threshold_is_set 41 * 42 * Tell if a write threshold is set for a given BDS. 43 */ 44 bool bdrv_write_threshold_is_set(const BlockDriverState *bs); 45 46 /* 47 * bdrv_write_threshold_exceeded 48 * 49 * Return the extent of a write request that exceeded the threshold, 50 * or zero if the request is below the threshold. 51 * Return zero also if the threshold was not set. 52 * 53 * NOTE: here we assume the following holds for each request this code 54 * deals with: 55 * 56 * assert((req->offset + req->bytes) <= UINT64_MAX) 57 * 58 * Please not there is *not* an actual C assert(). 59 */ 60 uint64_t bdrv_write_threshold_exceeded(const BlockDriverState *bs, 61 const BdrvTrackedRequest *req); 62 63 #endif 64