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xemu/blockjob.c
John Snow 5ccac6f186 blockjob: add block_job_start 
Instead of automatically starting jobs at creation time via backup_start
et al, we'd like to return a job object pointer that can be started
manually at later point in time.

For now, add the block_job_start mechanism and start the jobs
automatically as we have been doing, with conversions job-by-job coming
in later patches.

Of note: cancellation of unstarted jobs will perform all the normal
cleanup as if the job had started, particularly abort and clean. The
only difference is that we will not emit any events, because the job
never actually started.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1478587839-9834-5-git-send-email-jsnow@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
2016-11-14 22:47:34 -05:00

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/*
* QEMU System Emulator block driver
*
* Copyright (c) 2011 IBM Corp.
* Copyright (c) 2012 Red Hat, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu-common.h"
#include "trace.h"
#include "block/block.h"
#include "block/blockjob_int.h"
#include "block/block_int.h"
#include "sysemu/block-backend.h"
#include "qapi/qmp/qerror.h"
#include "qapi/qmp/qjson.h"
#include "qemu/coroutine.h"
#include "qemu/id.h"
#include "qmp-commands.h"
#include "qemu/timer.h"
#include "qapi-event.h"
static void block_job_event_cancelled(BlockJob *job);
static void block_job_event_completed(BlockJob *job, const char *msg);
/* Transactional group of block jobs */
struct BlockJobTxn {
/* Is this txn being cancelled? */
bool aborting;
/* List of jobs */
QLIST_HEAD(, BlockJob) jobs;
/* Reference count */
int refcnt;
};
static QLIST_HEAD(, BlockJob) block_jobs = QLIST_HEAD_INITIALIZER(block_jobs);
BlockJob *block_job_next(BlockJob *job)
{
if (!job) {
return QLIST_FIRST(&block_jobs);
}
return QLIST_NEXT(job, job_list);
}
BlockJob *block_job_get(const char *id)
{
BlockJob *job;
QLIST_FOREACH(job, &block_jobs, job_list) {
if (job->id && !strcmp(id, job->id)) {
return job;
}
}
return NULL;
}
static void block_job_attached_aio_context(AioContext *new_context,
void *opaque)
{
BlockJob *job = opaque;
if (job->driver->attached_aio_context) {
job->driver->attached_aio_context(job, new_context);
}
block_job_resume(job);
}
static void block_job_drain(BlockJob *job)
{
/* If job is !job->busy this kicks it into the next pause point. */
block_job_enter(job);
blk_drain(job->blk);
if (job->driver->drain) {
job->driver->drain(job);
}
}
static void block_job_detach_aio_context(void *opaque)
{
BlockJob *job = opaque;
/* In case the job terminates during aio_poll()... */
block_job_ref(job);
block_job_pause(job);
while (!job->paused && !job->completed) {
block_job_drain(job);
}
block_job_unref(job);
}
void block_job_add_bdrv(BlockJob *job, BlockDriverState *bs)
{
job->nodes = g_slist_prepend(job->nodes, bs);
bdrv_ref(bs);
bdrv_op_block_all(bs, job->blocker);
}
void *block_job_create(const char *job_id, const BlockJobDriver *driver,
BlockDriverState *bs, int64_t speed, int flags,
BlockCompletionFunc *cb, void *opaque, Error **errp)
{
BlockBackend *blk;
BlockJob *job;
if (bs->job) {
error_setg(errp, QERR_DEVICE_IN_USE, bdrv_get_device_name(bs));
return NULL;
}
if (job_id == NULL && !(flags & BLOCK_JOB_INTERNAL)) {
job_id = bdrv_get_device_name(bs);
if (!*job_id) {
error_setg(errp, "An explicit job ID is required for this node");
return NULL;
}
}
if (job_id) {
if (flags & BLOCK_JOB_INTERNAL) {
error_setg(errp, "Cannot specify job ID for internal block job");
return NULL;
}
if (!id_wellformed(job_id)) {
error_setg(errp, "Invalid job ID '%s'", job_id);
return NULL;
}
if (block_job_get(job_id)) {
error_setg(errp, "Job ID '%s' already in use", job_id);
return NULL;
}
}
blk = blk_new();
blk_insert_bs(blk, bs);
job = g_malloc0(driver->instance_size);
error_setg(&job->blocker, "block device is in use by block job: %s",
BlockJobType_lookup[driver->job_type]);
block_job_add_bdrv(job, bs);
bdrv_op_unblock(bs, BLOCK_OP_TYPE_DATAPLANE, job->blocker);
job->driver = driver;
job->id = g_strdup(job_id);
job->blk = blk;
job->cb = cb;
job->opaque = opaque;
job->busy = false;
job->paused = true;
job->pause_count = 1;
job->refcnt = 1;
bs->job = job;
QLIST_INSERT_HEAD(&block_jobs, job, job_list);
blk_add_aio_context_notifier(blk, block_job_attached_aio_context,
block_job_detach_aio_context, job);
/* Only set speed when necessary to avoid NotSupported error */
if (speed != 0) {
Error *local_err = NULL;
block_job_set_speed(job, speed, &local_err);
if (local_err) {
block_job_unref(job);
error_propagate(errp, local_err);
return NULL;
}
}
return job;
}
bool block_job_is_internal(BlockJob *job)
{
return (job->id == NULL);
}
static bool block_job_started(BlockJob *job)
{
return job->co;
}
void block_job_start(BlockJob *job)
{
assert(job && !block_job_started(job) && job->paused &&
!job->busy && job->driver->start);
job->co = qemu_coroutine_create(job->driver->start, job);
if (--job->pause_count == 0) {
job->paused = false;
job->busy = true;
qemu_coroutine_enter(job->co);
}
}
void block_job_ref(BlockJob *job)
{
++job->refcnt;
}
void block_job_unref(BlockJob *job)
{
if (--job->refcnt == 0) {
GSList *l;
BlockDriverState *bs = blk_bs(job->blk);
bs->job = NULL;
for (l = job->nodes; l; l = l->next) {
bs = l->data;
bdrv_op_unblock_all(bs, job->blocker);
bdrv_unref(bs);
}
g_slist_free(job->nodes);
blk_remove_aio_context_notifier(job->blk,
block_job_attached_aio_context,
block_job_detach_aio_context, job);
blk_unref(job->blk);
error_free(job->blocker);
g_free(job->id);
QLIST_REMOVE(job, job_list);
g_free(job);
}
}
static void block_job_completed_single(BlockJob *job)
{
if (!job->ret) {
if (job->driver->commit) {
job->driver->commit(job);
}
} else {
if (job->driver->abort) {
job->driver->abort(job);
}
}
if (job->driver->clean) {
job->driver->clean(job);
}
if (job->cb) {
job->cb(job->opaque, job->ret);
}
/* Emit events only if we actually started */
if (block_job_started(job)) {
if (block_job_is_cancelled(job)) {
block_job_event_cancelled(job);
} else {
const char *msg = NULL;
if (job->ret < 0) {
msg = strerror(-job->ret);
}
block_job_event_completed(job, msg);
}
}
if (job->txn) {
QLIST_REMOVE(job, txn_list);
block_job_txn_unref(job->txn);
}
block_job_unref(job);
}
static void block_job_completed_txn_abort(BlockJob *job)
{
AioContext *ctx;
BlockJobTxn *txn = job->txn;
BlockJob *other_job, *next;
if (txn->aborting) {
/*
* We are cancelled by another job, which will handle everything.
*/
return;
}
txn->aborting = true;
/* We are the first failed job. Cancel other jobs. */
QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
ctx = blk_get_aio_context(other_job->blk);
aio_context_acquire(ctx);
}
QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
if (other_job == job || other_job->completed) {
/* Other jobs are "effectively" cancelled by us, set the status for
* them; this job, however, may or may not be cancelled, depending
* on the caller, so leave it. */
if (other_job != job) {
other_job->cancelled = true;
}
continue;
}
block_job_cancel_sync(other_job);
assert(other_job->completed);
}
QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) {
ctx = blk_get_aio_context(other_job->blk);
block_job_completed_single(other_job);
aio_context_release(ctx);
}
}
static void block_job_completed_txn_success(BlockJob *job)
{
AioContext *ctx;
BlockJobTxn *txn = job->txn;
BlockJob *other_job, *next;
/*
* Successful completion, see if there are other running jobs in this
* txn.
*/
QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
if (!other_job->completed) {
return;
}
}
/* We are the last completed job, commit the transaction. */
QLIST_FOREACH_SAFE(other_job, &txn->jobs, txn_list, next) {
ctx = blk_get_aio_context(other_job->blk);
aio_context_acquire(ctx);
assert(other_job->ret == 0);
block_job_completed_single(other_job);
aio_context_release(ctx);
}
}
void block_job_completed(BlockJob *job, int ret)
{
assert(blk_bs(job->blk)->job == job);
assert(!job->completed);
job->completed = true;
job->ret = ret;
if (!job->txn) {
block_job_completed_single(job);
} else if (ret < 0 || block_job_is_cancelled(job)) {
block_job_completed_txn_abort(job);
} else {
block_job_completed_txn_success(job);
}
}
void block_job_set_speed(BlockJob *job, int64_t speed, Error **errp)
{
Error *local_err = NULL;
if (!job->driver->set_speed) {
error_setg(errp, QERR_UNSUPPORTED);
return;
}
job->driver->set_speed(job, speed, &local_err);
if (local_err) {
error_propagate(errp, local_err);
return;
}
job->speed = speed;
}
void block_job_complete(BlockJob *job, Error **errp)
{
/* Should not be reachable via external interface for internal jobs */
assert(job->id);
if (job->pause_count || job->cancelled ||
!block_job_started(job) || !job->driver->complete) {
error_setg(errp, "The active block job '%s' cannot be completed",
job->id);
return;
}
job->driver->complete(job, errp);
}
void block_job_pause(BlockJob *job)
{
job->pause_count++;
}
void block_job_user_pause(BlockJob *job)
{
job->user_paused = true;
block_job_pause(job);
}
static bool block_job_should_pause(BlockJob *job)
{
return job->pause_count > 0;
}
bool block_job_user_paused(BlockJob *job)
{
return job ? job->user_paused : 0;
}
void coroutine_fn block_job_pause_point(BlockJob *job)
{
assert(job && block_job_started(job));
if (!block_job_should_pause(job)) {
return;
}
if (block_job_is_cancelled(job)) {
return;
}
if (job->driver->pause) {
job->driver->pause(job);
}
if (block_job_should_pause(job) && !block_job_is_cancelled(job)) {
job->paused = true;
job->busy = false;
qemu_coroutine_yield(); /* wait for block_job_resume() */
job->busy = true;
job->paused = false;
}
if (job->driver->resume) {
job->driver->resume(job);
}
}
void block_job_resume(BlockJob *job)
{
assert(job->pause_count > 0);
job->pause_count--;
if (job->pause_count) {
return;
}
block_job_enter(job);
}
void block_job_user_resume(BlockJob *job)
{
if (job && job->user_paused && job->pause_count > 0) {
job->user_paused = false;
block_job_resume(job);
}
}
void block_job_enter(BlockJob *job)
{
if (job->co && !job->busy) {
qemu_coroutine_enter(job->co);
}
}
void block_job_cancel(BlockJob *job)
{
if (block_job_started(job)) {
job->cancelled = true;
block_job_iostatus_reset(job);
block_job_enter(job);
} else {
block_job_completed(job, -ECANCELED);
}
}
bool block_job_is_cancelled(BlockJob *job)
{
return job->cancelled;
}
void block_job_iostatus_reset(BlockJob *job)
{
job->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
if (job->driver->iostatus_reset) {
job->driver->iostatus_reset(job);
}
}
static int block_job_finish_sync(BlockJob *job,
void (*finish)(BlockJob *, Error **errp),
Error **errp)
{
Error *local_err = NULL;
int ret;
assert(blk_bs(job->blk)->job == job);
block_job_ref(job);
finish(job, &local_err);
if (local_err) {
error_propagate(errp, local_err);
block_job_unref(job);
return -EBUSY;
}
/* block_job_drain calls block_job_enter, and it should be enough to
* induce progress until the job completes or moves to the main thread.
*/
while (!job->deferred_to_main_loop && !job->completed) {
block_job_drain(job);
}
while (!job->completed) {
aio_poll(qemu_get_aio_context(), true);
}
ret = (job->cancelled && job->ret == 0) ? -ECANCELED : job->ret;
block_job_unref(job);
return ret;
}
/* A wrapper around block_job_cancel() taking an Error ** parameter so it may be
* used with block_job_finish_sync() without the need for (rather nasty)
* function pointer casts there. */
static void block_job_cancel_err(BlockJob *job, Error **errp)
{
block_job_cancel(job);
}
int block_job_cancel_sync(BlockJob *job)
{
return block_job_finish_sync(job, &block_job_cancel_err, NULL);
}
void block_job_cancel_sync_all(void)
{
BlockJob *job;
AioContext *aio_context;
while ((job = QLIST_FIRST(&block_jobs))) {
aio_context = blk_get_aio_context(job->blk);
aio_context_acquire(aio_context);
block_job_cancel_sync(job);
aio_context_release(aio_context);
}
}
int block_job_complete_sync(BlockJob *job, Error **errp)
{
return block_job_finish_sync(job, &block_job_complete, errp);
}
void block_job_sleep_ns(BlockJob *job, QEMUClockType type, int64_t ns)
{
assert(job->busy);
/* Check cancellation *before* setting busy = false, too! */
if (block_job_is_cancelled(job)) {
return;
}
job->busy = false;
if (!block_job_should_pause(job)) {
co_aio_sleep_ns(blk_get_aio_context(job->blk), type, ns);
}
job->busy = true;
block_job_pause_point(job);
}
void block_job_yield(BlockJob *job)
{
assert(job->busy);
/* Check cancellation *before* setting busy = false, too! */
if (block_job_is_cancelled(job)) {
return;
}
job->busy = false;
if (!block_job_should_pause(job)) {
qemu_coroutine_yield();
}
job->busy = true;
block_job_pause_point(job);
}
BlockJobInfo *block_job_query(BlockJob *job, Error **errp)
{
BlockJobInfo *info;
if (block_job_is_internal(job)) {
error_setg(errp, "Cannot query QEMU internal jobs");
return NULL;
}
info = g_new0(BlockJobInfo, 1);
info->type = g_strdup(BlockJobType_lookup[job->driver->job_type]);
info->device = g_strdup(job->id);
info->len = job->len;
info->busy = job->busy;
info->paused = job->pause_count > 0;
info->offset = job->offset;
info->speed = job->speed;
info->io_status = job->iostatus;
info->ready = job->ready;
return info;
}
static void block_job_iostatus_set_err(BlockJob *job, int error)
{
if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
job->iostatus = error == ENOSPC ? BLOCK_DEVICE_IO_STATUS_NOSPACE :
BLOCK_DEVICE_IO_STATUS_FAILED;
}
}
static void block_job_event_cancelled(BlockJob *job)
{
if (block_job_is_internal(job)) {
return;
}
qapi_event_send_block_job_cancelled(job->driver->job_type,
job->id,
job->len,
job->offset,
job->speed,
&error_abort);
}
static void block_job_event_completed(BlockJob *job, const char *msg)
{
if (block_job_is_internal(job)) {
return;
}
qapi_event_send_block_job_completed(job->driver->job_type,
job->id,
job->len,
job->offset,
job->speed,
!!msg,
msg,
&error_abort);
}
void block_job_event_ready(BlockJob *job)
{
job->ready = true;
if (block_job_is_internal(job)) {
return;
}
qapi_event_send_block_job_ready(job->driver->job_type,
job->id,
job->len,
job->offset,
job->speed, &error_abort);
}
BlockErrorAction block_job_error_action(BlockJob *job, BlockdevOnError on_err,
int is_read, int error)
{
BlockErrorAction action;
switch (on_err) {
case BLOCKDEV_ON_ERROR_ENOSPC:
case BLOCKDEV_ON_ERROR_AUTO:
action = (error == ENOSPC) ?
BLOCK_ERROR_ACTION_STOP : BLOCK_ERROR_ACTION_REPORT;
break;
case BLOCKDEV_ON_ERROR_STOP:
action = BLOCK_ERROR_ACTION_STOP;
break;
case BLOCKDEV_ON_ERROR_REPORT:
action = BLOCK_ERROR_ACTION_REPORT;
break;
case BLOCKDEV_ON_ERROR_IGNORE:
action = BLOCK_ERROR_ACTION_IGNORE;
break;
default:
abort();
}
if (!block_job_is_internal(job)) {
qapi_event_send_block_job_error(job->id,
is_read ? IO_OPERATION_TYPE_READ :
IO_OPERATION_TYPE_WRITE,
action, &error_abort);
}
if (action == BLOCK_ERROR_ACTION_STOP) {
/* make the pause user visible, which will be resumed from QMP. */
block_job_user_pause(job);
block_job_iostatus_set_err(job, error);
}
return action;
}
typedef struct {
BlockJob *job;
AioContext *aio_context;
BlockJobDeferToMainLoopFn *fn;
void *opaque;
} BlockJobDeferToMainLoopData;
static void block_job_defer_to_main_loop_bh(void *opaque)
{
BlockJobDeferToMainLoopData *data = opaque;
AioContext *aio_context;
/* Prevent race with block_job_defer_to_main_loop() */
aio_context_acquire(data->aio_context);
/* Fetch BDS AioContext again, in case it has changed */
aio_context = blk_get_aio_context(data->job->blk);
aio_context_acquire(aio_context);
data->job->deferred_to_main_loop = false;
data->fn(data->job, data->opaque);
aio_context_release(aio_context);
aio_context_release(data->aio_context);
g_free(data);
}
void block_job_defer_to_main_loop(BlockJob *job,
BlockJobDeferToMainLoopFn *fn,
void *opaque)
{
BlockJobDeferToMainLoopData *data = g_malloc(sizeof(*data));
data->job = job;
data->aio_context = blk_get_aio_context(job->blk);
data->fn = fn;
data->opaque = opaque;
job->deferred_to_main_loop = true;
aio_bh_schedule_oneshot(qemu_get_aio_context(),
block_job_defer_to_main_loop_bh, data);
}
BlockJobTxn *block_job_txn_new(void)
{
BlockJobTxn *txn = g_new0(BlockJobTxn, 1);
QLIST_INIT(&txn->jobs);
txn->refcnt = 1;
return txn;
}
static void block_job_txn_ref(BlockJobTxn *txn)
{
txn->refcnt++;
}
void block_job_txn_unref(BlockJobTxn *txn)
{
if (txn && --txn->refcnt == 0) {
g_free(txn);
}
}
void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job)
{
if (!txn) {
return;
}
assert(!job->txn);
job->txn = txn;
QLIST_INSERT_HEAD(&txn->jobs, job, txn_list);
block_job_txn_ref(txn);
}
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