2020-09-24 17:26:50 +02:00
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/*
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* Common block export infrastructure
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*
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* Copyright (c) 2012, 2020 Red Hat, Inc.
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*
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* Authors:
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* Paolo Bonzini <pbonzini@redhat.com>
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* Kevin Wolf <kwolf@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or
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* later. See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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2020-09-24 17:26:53 +02:00
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#include "block/block.h"
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#include "sysemu/block-backend.h"
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2020-09-24 17:26:50 +02:00
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#include "block/export.h"
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#include "block/nbd.h"
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#include "qapi/error.h"
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#include "qapi/qapi-commands-block-export.h"
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2020-09-24 17:27:04 +02:00
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#include "qemu/id.h"
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2020-09-24 17:26:50 +02:00
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static const BlockExportDriver *blk_exp_drivers[] = {
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&blk_exp_nbd,
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};
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2020-09-24 17:27:03 +02:00
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/* Only accessed from the main thread */
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static QLIST_HEAD(, BlockExport) block_exports =
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QLIST_HEAD_INITIALIZER(block_exports);
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2020-09-24 17:27:06 +02:00
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BlockExport *blk_exp_find(const char *id)
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2020-09-24 17:27:04 +02:00
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{
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BlockExport *exp;
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QLIST_FOREACH(exp, &block_exports, next) {
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if (strcmp(id, exp->id) == 0) {
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return exp;
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}
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}
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return NULL;
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}
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2020-09-24 17:26:50 +02:00
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static const BlockExportDriver *blk_exp_find_driver(BlockExportType type)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(blk_exp_drivers); i++) {
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if (blk_exp_drivers[i]->type == type) {
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return blk_exp_drivers[i];
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}
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}
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return NULL;
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}
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2020-09-24 17:26:53 +02:00
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BlockExport *blk_exp_add(BlockExportOptions *export, Error **errp)
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2020-09-24 17:26:50 +02:00
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{
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const BlockExportDriver *drv;
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2020-09-24 17:27:02 +02:00
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BlockExport *exp;
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int ret;
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2020-09-24 17:26:50 +02:00
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2020-09-24 17:27:04 +02:00
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if (!id_wellformed(export->id)) {
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error_setg(errp, "Invalid block export id");
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return NULL;
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}
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if (blk_exp_find(export->id)) {
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error_setg(errp, "Block export id '%s' is already in use", export->id);
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return NULL;
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}
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2020-09-24 17:26:50 +02:00
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drv = blk_exp_find_driver(export->type);
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if (!drv) {
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error_setg(errp, "No driver found for the requested export type");
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2020-09-24 17:26:53 +02:00
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return NULL;
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2020-09-24 17:26:50 +02:00
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}
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2020-09-24 17:27:02 +02:00
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assert(drv->instance_size >= sizeof(BlockExport));
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exp = g_malloc0(drv->instance_size);
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*exp = (BlockExport) {
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.drv = drv,
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.refcount = 1,
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2020-09-24 17:27:05 +02:00
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.user_owned = true,
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2020-09-24 17:27:04 +02:00
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.id = g_strdup(export->id),
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2020-09-24 17:27:02 +02:00
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};
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ret = drv->create(exp, export, errp);
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if (ret < 0) {
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2020-09-24 17:27:04 +02:00
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g_free(exp->id);
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2020-09-24 17:27:02 +02:00
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g_free(exp);
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return NULL;
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}
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2020-09-24 17:27:03 +02:00
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QLIST_INSERT_HEAD(&block_exports, exp, next);
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2020-09-24 17:27:02 +02:00
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return exp;
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2020-09-24 17:26:53 +02:00
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}
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2020-09-24 17:27:00 +02:00
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/* Callers must hold exp->ctx lock */
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2020-09-24 17:26:59 +02:00
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void blk_exp_ref(BlockExport *exp)
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{
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assert(exp->refcount > 0);
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exp->refcount++;
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}
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2020-09-24 17:27:03 +02:00
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/* Runs in the main thread */
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static void blk_exp_delete_bh(void *opaque)
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{
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BlockExport *exp = opaque;
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AioContext *aio_context = exp->ctx;
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aio_context_acquire(aio_context);
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assert(exp->refcount == 0);
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QLIST_REMOVE(exp, next);
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exp->drv->delete(exp);
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2020-09-24 17:27:04 +02:00
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g_free(exp->id);
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2020-09-24 17:27:03 +02:00
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g_free(exp);
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aio_context_release(aio_context);
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}
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2020-09-24 17:27:00 +02:00
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/* Callers must hold exp->ctx lock */
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2020-09-24 17:26:59 +02:00
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void blk_exp_unref(BlockExport *exp)
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{
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assert(exp->refcount > 0);
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if (--exp->refcount == 0) {
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2020-09-24 17:27:03 +02:00
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/* Touch the block_exports list only in the main thread */
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aio_bh_schedule_oneshot(qemu_get_aio_context(), blk_exp_delete_bh,
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exp);
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}
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}
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/*
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* Drops the user reference to the export and requests that all client
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* connections and other internally held references start to shut down. When
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* the function returns, there may still be active references while the export
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* is in the process of shutting down.
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*
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* Acquires exp->ctx internally. Callers must *not* hold the lock.
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*/
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void blk_exp_request_shutdown(BlockExport *exp)
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{
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AioContext *aio_context = exp->ctx;
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aio_context_acquire(aio_context);
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2020-09-24 17:27:06 +02:00
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/*
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* If the user doesn't own the export any more, it is already shutting
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* down. We must not call .request_shutdown and decrease the refcount a
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* second time.
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*/
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if (!exp->user_owned) {
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goto out;
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}
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2020-09-24 17:27:03 +02:00
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exp->drv->request_shutdown(exp);
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2020-09-24 17:27:05 +02:00
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assert(exp->user_owned);
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exp->user_owned = false;
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blk_exp_unref(exp);
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2020-09-24 17:27:06 +02:00
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out:
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2020-09-24 17:27:03 +02:00
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aio_context_release(aio_context);
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}
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/*
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* Returns whether a block export of the given type exists.
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* type == BLOCK_EXPORT_TYPE__MAX checks for an export of any type.
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*/
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static bool blk_exp_has_type(BlockExportType type)
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{
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BlockExport *exp;
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if (type == BLOCK_EXPORT_TYPE__MAX) {
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return !QLIST_EMPTY(&block_exports);
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}
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QLIST_FOREACH(exp, &block_exports, next) {
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if (exp->drv->type == type) {
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return true;
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}
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2020-09-24 17:26:59 +02:00
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}
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2020-09-24 17:27:03 +02:00
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return false;
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}
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/* type == BLOCK_EXPORT_TYPE__MAX for all types */
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void blk_exp_close_all_type(BlockExportType type)
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{
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BlockExport *exp, *next;
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assert(in_aio_context_home_thread(qemu_get_aio_context()));
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QLIST_FOREACH_SAFE(exp, &block_exports, next, next) {
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if (type != BLOCK_EXPORT_TYPE__MAX && exp->drv->type != type) {
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continue;
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}
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blk_exp_request_shutdown(exp);
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}
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AIO_WAIT_WHILE(NULL, blk_exp_has_type(type));
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}
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void blk_exp_close_all(void)
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{
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blk_exp_close_all_type(BLOCK_EXPORT_TYPE__MAX);
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2020-09-24 17:26:59 +02:00
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}
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2020-09-24 17:26:53 +02:00
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void qmp_block_export_add(BlockExportOptions *export, Error **errp)
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{
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blk_exp_add(export, errp);
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2020-09-24 17:26:50 +02:00
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}
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2020-09-24 17:27:06 +02:00
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void qmp_block_export_del(const char *id,
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bool has_mode, BlockExportRemoveMode mode,
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Error **errp)
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{
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ERRP_GUARD();
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BlockExport *exp;
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exp = blk_exp_find(id);
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if (exp == NULL) {
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error_setg(errp, "Export '%s' is not found", id);
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return;
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}
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if (!exp->user_owned) {
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error_setg(errp, "Export '%s' is already shutting down", id);
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return;
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}
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if (!has_mode) {
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mode = BLOCK_EXPORT_REMOVE_MODE_SAFE;
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}
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if (mode == BLOCK_EXPORT_REMOVE_MODE_SAFE && exp->refcount > 1) {
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error_setg(errp, "export '%s' still in use", exp->id);
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error_append_hint(errp, "Use mode='hard' to force client "
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"disconnect\n");
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return;
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}
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blk_exp_request_shutdown(exp);
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}
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