127 lines
3.5 KiB
C
127 lines
3.5 KiB
C
/*
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* QEMU System Emulator block write threshold notification
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*
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* Copyright Red Hat, Inc. 2014
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*
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* Authors:
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* Francesco Romani <fromani@redhat.com>
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*
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* This work is licensed under the terms of the GNU LGPL, version 2 or later.
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* See the COPYING.LIB file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "block/block_int.h"
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#include "qemu/coroutine.h"
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#include "block/write-threshold.h"
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#include "qemu/notify.h"
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#include "qapi-event.h"
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#include "qmp-commands.h"
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uint64_t bdrv_write_threshold_get(const BlockDriverState *bs)
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{
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return bs->write_threshold_offset;
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}
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bool bdrv_write_threshold_is_set(const BlockDriverState *bs)
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{
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return bs->write_threshold_offset > 0;
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}
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static void write_threshold_disable(BlockDriverState *bs)
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{
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if (bdrv_write_threshold_is_set(bs)) {
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notifier_with_return_remove(&bs->write_threshold_notifier);
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bs->write_threshold_offset = 0;
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}
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}
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uint64_t bdrv_write_threshold_exceeded(const BlockDriverState *bs,
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const BdrvTrackedRequest *req)
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{
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if (bdrv_write_threshold_is_set(bs)) {
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if (req->offset > bs->write_threshold_offset) {
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return (req->offset - bs->write_threshold_offset) + req->bytes;
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}
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if ((req->offset + req->bytes) > bs->write_threshold_offset) {
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return (req->offset + req->bytes) - bs->write_threshold_offset;
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}
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}
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return 0;
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}
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static int coroutine_fn before_write_notify(NotifierWithReturn *notifier,
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void *opaque)
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{
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BdrvTrackedRequest *req = opaque;
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BlockDriverState *bs = req->bs;
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uint64_t amount = 0;
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amount = bdrv_write_threshold_exceeded(bs, req);
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if (amount > 0) {
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qapi_event_send_block_write_threshold(
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bs->node_name,
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amount,
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bs->write_threshold_offset,
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&error_abort);
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/* autodisable to avoid flooding the monitor */
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write_threshold_disable(bs);
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}
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return 0; /* should always let other notifiers run */
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}
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static void write_threshold_register_notifier(BlockDriverState *bs)
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{
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bs->write_threshold_notifier.notify = before_write_notify;
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notifier_with_return_list_add(&bs->before_write_notifiers,
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&bs->write_threshold_notifier);
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}
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static void write_threshold_update(BlockDriverState *bs,
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int64_t threshold_bytes)
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{
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bs->write_threshold_offset = threshold_bytes;
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}
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void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes)
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{
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if (bdrv_write_threshold_is_set(bs)) {
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if (threshold_bytes > 0) {
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write_threshold_update(bs, threshold_bytes);
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} else {
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write_threshold_disable(bs);
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}
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} else {
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if (threshold_bytes > 0) {
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/* avoid multiple registration */
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write_threshold_register_notifier(bs);
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write_threshold_update(bs, threshold_bytes);
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}
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/* discard bogus disable request */
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}
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}
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void qmp_block_set_write_threshold(const char *node_name,
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uint64_t threshold_bytes,
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Error **errp)
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{
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BlockDriverState *bs;
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AioContext *aio_context;
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bs = bdrv_find_node(node_name);
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if (!bs) {
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error_setg(errp, "Device '%s' not found", node_name);
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return;
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}
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aio_context = bdrv_get_aio_context(bs);
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aio_context_acquire(aio_context);
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bdrv_write_threshold_set(bs, threshold_bytes);
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aio_context_release(aio_context);
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}
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