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xemu/blockjob.c
sochin.jiang 4172a00373 fix: avoid an infinite loop or a dangling pointer problem in img_commit 
img_commit could fall into an infinite loop calling run_block_job() if
its blockjob fails on any I/O error, fix this already known problem.

Signed-off-by: sochin.jiang <sochin.jiang@huawei.com>
Message-id: 1497509253-28941-1-git-send-email-sochin.jiang@huawei.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-06-26 14:54:46 +02:00

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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 "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);
/*
* The block job API is composed of two categories of functions.
*
* The first includes functions used by the monitor. The monitor is
* peculiar in that it accesses the block job list with block_job_get, and
* therefore needs consistency across block_job_get and the actual operation
* (e.g. block_job_set_speed). The consistency is achieved with
* aio_context_acquire/release. These functions are declared in blockjob.h.
*
* The second includes functions used by the block job drivers and sometimes
* by the core block layer. These do not care about locking, because the
* whole coroutine runs under the AioContext lock, and are declared in
* blockjob_int.h.
*/
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;
}
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);
}
static void block_job_pause(BlockJob *job)
{
job->pause_count++;
}
static 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_ref(BlockJob *job)
{
++job->refcnt;
}
static void block_job_attached_aio_context(AioContext *new_context,
void *opaque);
static void block_job_detach_aio_context(void *opaque);
void block_job_unref(BlockJob *job)
{
if (--job->refcnt == 0) {
BlockDriverState *bs = blk_bs(job->blk);
bs->job = NULL;
block_job_remove_all_bdrv(job);
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_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);
}
static char *child_job_get_parent_desc(BdrvChild *c)
{
BlockJob *job = c->opaque;
return g_strdup_printf("%s job '%s'",
BlockJobType_lookup[job->driver->job_type],
job->id);
}
static const BdrvChildRole child_job = {
.get_parent_desc = child_job_get_parent_desc,
.stay_at_node = true,
};
static void block_job_drained_begin(void *opaque)
{
BlockJob *job = opaque;
block_job_pause(job);
}
static void block_job_drained_end(void *opaque)
{
BlockJob *job = opaque;
block_job_resume(job);
}
static const BlockDevOps block_job_dev_ops = {
.drained_begin = block_job_drained_begin,
.drained_end = block_job_drained_end,
};
void block_job_remove_all_bdrv(BlockJob *job)
{
GSList *l;
for (l = job->nodes; l; l = l->next) {
BdrvChild *c = l->data;
bdrv_op_unblock_all(c->bs, job->blocker);
bdrv_root_unref_child(c);
}
g_slist_free(job->nodes);
job->nodes = NULL;
}
int block_job_add_bdrv(BlockJob *job, const char *name, BlockDriverState *bs,
uint64_t perm, uint64_t shared_perm, Error **errp)
{
BdrvChild *c;
c = bdrv_root_attach_child(bs, name, &child_job, perm, shared_perm,
job, errp);
if (c == NULL) {
return -EPERM;
}
job->nodes = g_slist_prepend(job->nodes, c);
bdrv_ref(bs);
bdrv_op_block_all(bs, job->blocker);
return 0;
}
bool block_job_is_internal(BlockJob *job)
{
return (job->id == NULL);
}
static bool block_job_started(BlockJob *job)
{
return job->co;
}
/**
* All jobs must allow a pause point before entering their job proper. This
* ensures that jobs can be paused prior to being started, then resumed later.
*/
static void coroutine_fn block_job_co_entry(void *opaque)
{
BlockJob *job = opaque;
assert(job && job->driver && job->driver->start);
block_job_pause_point(job);
job->driver->start(job);
}
void block_job_start(BlockJob *job)
{
assert(job && !block_job_started(job) && job->paused &&
job->driver && job->driver->start);
job->co = qemu_coroutine_create(block_job_co_entry, job);
job->pause_count--;
job->busy = true;
job->paused = false;
bdrv_coroutine_enter(blk_bs(job->blk), job->co);
}
static void block_job_completed_single(BlockJob *job)
{
assert(job->completed);
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_cancel_async(BlockJob *job)
{
if (job->iostatus != BLOCK_DEVICE_IO_STATUS_OK) {
block_job_iostatus_reset(job);
}
if (job->user_paused) {
/* Do not call block_job_enter here, the caller will handle it. */
job->user_paused = false;
job->pause_count--;
}
job->cancelled = true;
}
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);
if (finish) {
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;
}
static void block_job_completed_txn_abort(BlockJob *job)
{
AioContext *ctx;
BlockJobTxn *txn = job->txn;
BlockJob *other_job;
if (txn->aborting) {
/*
* We are cancelled by another job, which will handle everything.
*/
return;
}
txn->aborting = true;
block_job_txn_ref(txn);
/* 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);
}
/* 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. */
QLIST_FOREACH(other_job, &txn->jobs, txn_list) {
if (other_job != job) {
block_job_cancel_async(other_job);
}
}
while (!QLIST_EMPTY(&txn->jobs)) {
other_job = QLIST_FIRST(&txn->jobs);
ctx = blk_get_aio_context(other_job->blk);
if (!other_job->completed) {
assert(other_job->cancelled);
block_job_finish_sync(other_job, NULL, NULL);
}
block_job_completed_single(other_job);
aio_context_release(ctx);
}
block_job_txn_unref(txn);
}
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_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_user_pause(BlockJob *job)
{
job->user_paused = true;
block_job_pause(job);
}
bool block_job_user_paused(BlockJob *job)
{
return job->user_paused;
}
void block_job_user_resume(BlockJob *job)
{
if (job && job->user_paused && job->pause_count > 0) {
block_job_iostatus_reset(job);
job->user_paused = false;
block_job_resume(job);
}
}
void block_job_cancel(BlockJob *job)
{
if (block_job_started(job)) {
block_job_cancel_async(job);
block_job_enter(job);
} else {
block_job_completed(job, -ECANCELED);
}
}
/* 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);
}
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);
}
/*
* API for block job drivers and the block layer. These functions are
* declared in blockjob_int.h.
*/
void *block_job_create(const char *job_id, const BlockJobDriver *driver,
BlockDriverState *bs, uint64_t perm,
uint64_t shared_perm, int64_t speed, int flags,
BlockCompletionFunc *cb, void *opaque, Error **errp)
{
BlockBackend *blk;
BlockJob *job;
int ret;
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(perm, shared_perm);
ret = blk_insert_bs(blk, bs, errp);
if (ret < 0) {
blk_unref(blk);
return NULL;
}
job = g_malloc0(driver->instance_size);
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;
error_setg(&job->blocker, "block device is in use by block job: %s",
BlockJobType_lookup[driver->job_type]);
block_job_add_bdrv(job, "main node", bs, 0, BLK_PERM_ALL, &error_abort);
bs->job = job;
blk_set_dev_ops(blk, &block_job_dev_ops, job);
bdrv_op_unblock(bs, BLOCK_OP_TYPE_DATAPLANE, job->blocker);
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;
}
void block_job_pause_all(void)
{
BlockJob *job = NULL;
while ((job = block_job_next(job))) {
AioContext *aio_context = blk_get_aio_context(job->blk);
aio_context_acquire(aio_context);
block_job_pause(job);
aio_context_release(aio_context);
}
}
void block_job_early_fail(BlockJob *job)
{
block_job_unref(job);
}
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);
}
}
static bool block_job_should_pause(BlockJob *job)
{
return job->pause_count > 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_all(void)
{
BlockJob *job = NULL;
while ((job = block_job_next(job))) {
AioContext *aio_context = blk_get_aio_context(job->blk);
aio_context_acquire(aio_context);
block_job_resume(job);
aio_context_release(aio_context);
}
}
void block_job_enter(BlockJob *job)
{
if (!block_job_started(job)) {
return;
}
if (job->deferred_to_main_loop) {
return;
}
if (!job->busy) {
bdrv_coroutine_enter(blk_bs(job->blk), job->co);
}
}
bool block_job_is_cancelled(BlockJob *job)
{
return job->cancelled;
}
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);
}
void block_job_iostatus_reset(BlockJob *job)
{
if (job->iostatus == BLOCK_DEVICE_IO_STATUS_OK) {
return;
}
assert(job->user_paused && job->pause_count > 0);
job->iostatus = BLOCK_DEVICE_IO_STATUS_OK;
}
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);
if (aio_context != data->aio_context) {
aio_context_acquire(aio_context);
}
data->fn(data->job, data->opaque);
if (aio_context != data->aio_context) {
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);
}
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