/* * 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. */ #include "qemu/osdep.h" #include "block/block_int.h" #include "qemu/coroutine.h" #include "block/write-threshold.h" #include "qemu/notify.h" #include "qapi-event.h" #include "qmp-commands.h" uint64_t bdrv_write_threshold_get(const BlockDriverState *bs) { return bs->write_threshold_offset; } bool bdrv_write_threshold_is_set(const BlockDriverState *bs) { return bs->write_threshold_offset > 0; } static void write_threshold_disable(BlockDriverState *bs) { if (bdrv_write_threshold_is_set(bs)) { notifier_with_return_remove(&bs->write_threshold_notifier); bs->write_threshold_offset = 0; } } uint64_t bdrv_write_threshold_exceeded(const BlockDriverState *bs, const BdrvTrackedRequest *req) { if (bdrv_write_threshold_is_set(bs)) { if (req->offset > bs->write_threshold_offset) { return (req->offset - bs->write_threshold_offset) + req->bytes; } if ((req->offset + req->bytes) > bs->write_threshold_offset) { return (req->offset + req->bytes) - bs->write_threshold_offset; } } return 0; } static int coroutine_fn before_write_notify(NotifierWithReturn *notifier, void *opaque) { BdrvTrackedRequest *req = opaque; BlockDriverState *bs = req->bs; uint64_t amount = 0; amount = bdrv_write_threshold_exceeded(bs, req); if (amount > 0) { qapi_event_send_block_write_threshold( bs->node_name, amount, bs->write_threshold_offset, &error_abort); /* autodisable to avoid flooding the monitor */ write_threshold_disable(bs); } return 0; /* should always let other notifiers run */ } static void write_threshold_register_notifier(BlockDriverState *bs) { bs->write_threshold_notifier.notify = before_write_notify; bdrv_add_before_write_notifier(bs, &bs->write_threshold_notifier); } static void write_threshold_update(BlockDriverState *bs, int64_t threshold_bytes) { bs->write_threshold_offset = threshold_bytes; } void bdrv_write_threshold_set(BlockDriverState *bs, uint64_t threshold_bytes) { if (bdrv_write_threshold_is_set(bs)) { if (threshold_bytes > 0) { write_threshold_update(bs, threshold_bytes); } else { write_threshold_disable(bs); } } else { if (threshold_bytes > 0) { /* avoid multiple registration */ write_threshold_register_notifier(bs); write_threshold_update(bs, threshold_bytes); } /* discard bogus disable request */ } } void qmp_block_set_write_threshold(const char *node_name, uint64_t threshold_bytes, Error **errp) { BlockDriverState *bs; AioContext *aio_context; bs = bdrv_find_node(node_name); if (!bs) { error_setg(errp, "Device '%s' not found", node_name); return; } aio_context = bdrv_get_aio_context(bs); aio_context_acquire(aio_context); bdrv_write_threshold_set(bs, threshold_bytes); aio_context_release(aio_context); }