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qemu/block/backup.c
Wenchao Xia a589569f2f qapi: adjust existing defines 
In order to let event defines use existing types later, instead of
redefine new ones, some old type defines for spice and vnc are changed,
and BlockErrorAction is moved from block.h to qapi schema. Note that
BlockErrorAction is not merged with BlockdevOnError.

At this point, VncInfo is not made a child of VncBasicInfo, because
VncBasicInfo has mandatory fields where VncInfo makes them optional.

Signed-off-by: Wenchao Xia <wenchaoqemu@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
2014-06-23 11:01:25 -04:00

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/*
* QEMU backup
*
* Copyright (C) 2013 Proxmox Server Solutions
*
* Authors:
* Dietmar Maurer (dietmar@proxmox.com)
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include "trace.h"
#include "block/block.h"
#include "block/block_int.h"
#include "block/blockjob.h"
#include "qemu/ratelimit.h"
#define BACKUP_CLUSTER_BITS 16
#define BACKUP_CLUSTER_SIZE (1 << BACKUP_CLUSTER_BITS)
#define BACKUP_SECTORS_PER_CLUSTER (BACKUP_CLUSTER_SIZE / BDRV_SECTOR_SIZE)
#define SLICE_TIME 100000000ULL /* ns */
typedef struct CowRequest {
int64_t start;
int64_t end;
QLIST_ENTRY(CowRequest) list;
CoQueue wait_queue; /* coroutines blocked on this request */
} CowRequest;
typedef struct BackupBlockJob {
BlockJob common;
BlockDriverState *target;
MirrorSyncMode sync_mode;
RateLimit limit;
BlockdevOnError on_source_error;
BlockdevOnError on_target_error;
CoRwlock flush_rwlock;
uint64_t sectors_read;
HBitmap *bitmap;
QLIST_HEAD(, CowRequest) inflight_reqs;
} BackupBlockJob;
/* See if in-flight requests overlap and wait for them to complete */
static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
int64_t start,
int64_t end)
{
CowRequest *req;
bool retry;
do {
retry = false;
QLIST_FOREACH(req, &job->inflight_reqs, list) {
if (end > req->start && start < req->end) {
qemu_co_queue_wait(&req->wait_queue);
retry = true;
break;
}
}
} while (retry);
}
/* Keep track of an in-flight request */
static void cow_request_begin(CowRequest *req, BackupBlockJob *job,
int64_t start, int64_t end)
{
req->start = start;
req->end = end;
qemu_co_queue_init(&req->wait_queue);
QLIST_INSERT_HEAD(&job->inflight_reqs, req, list);
}
/* Forget about a completed request */
static void cow_request_end(CowRequest *req)
{
QLIST_REMOVE(req, list);
qemu_co_queue_restart_all(&req->wait_queue);
}
static int coroutine_fn backup_do_cow(BlockDriverState *bs,
int64_t sector_num, int nb_sectors,
bool *error_is_read)
{
BackupBlockJob *job = (BackupBlockJob *)bs->job;
CowRequest cow_request;
struct iovec iov;
QEMUIOVector bounce_qiov;
void *bounce_buffer = NULL;
int ret = 0;
int64_t start, end;
int n;
qemu_co_rwlock_rdlock(&job->flush_rwlock);
start = sector_num / BACKUP_SECTORS_PER_CLUSTER;
end = DIV_ROUND_UP(sector_num + nb_sectors, BACKUP_SECTORS_PER_CLUSTER);
trace_backup_do_cow_enter(job, start, sector_num, nb_sectors);
wait_for_overlapping_requests(job, start, end);
cow_request_begin(&cow_request, job, start, end);
for (; start < end; start++) {
if (hbitmap_get(job->bitmap, start)) {
trace_backup_do_cow_skip(job, start);
continue; /* already copied */
}
trace_backup_do_cow_process(job, start);
n = MIN(BACKUP_SECTORS_PER_CLUSTER,
job->common.len / BDRV_SECTOR_SIZE -
start * BACKUP_SECTORS_PER_CLUSTER);
if (!bounce_buffer) {
bounce_buffer = qemu_blockalign(bs, BACKUP_CLUSTER_SIZE);
}
iov.iov_base = bounce_buffer;
iov.iov_len = n * BDRV_SECTOR_SIZE;
qemu_iovec_init_external(&bounce_qiov, &iov, 1);
ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n,
&bounce_qiov);
if (ret < 0) {
trace_backup_do_cow_read_fail(job, start, ret);
if (error_is_read) {
*error_is_read = true;
}
goto out;
}
if (buffer_is_zero(iov.iov_base, iov.iov_len)) {
ret = bdrv_co_write_zeroes(job->target,
start * BACKUP_SECTORS_PER_CLUSTER,
n, BDRV_REQ_MAY_UNMAP);
} else {
ret = bdrv_co_writev(job->target,
start * BACKUP_SECTORS_PER_CLUSTER, n,
&bounce_qiov);
}
if (ret < 0) {
trace_backup_do_cow_write_fail(job, start, ret);
if (error_is_read) {
*error_is_read = false;
}
goto out;
}
hbitmap_set(job->bitmap, start, 1);
/* Publish progress, guest I/O counts as progress too. Note that the
* offset field is an opaque progress value, it is not a disk offset.
*/
job->sectors_read += n;
job->common.offset += n * BDRV_SECTOR_SIZE;
}
out:
if (bounce_buffer) {
qemu_vfree(bounce_buffer);
}
cow_request_end(&cow_request);
trace_backup_do_cow_return(job, sector_num, nb_sectors, ret);
qemu_co_rwlock_unlock(&job->flush_rwlock);
return ret;
}
static int coroutine_fn backup_before_write_notify(
NotifierWithReturn *notifier,
void *opaque)
{
BdrvTrackedRequest *req = opaque;
int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
return backup_do_cow(req->bs, sector_num, nb_sectors, NULL);
}
static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common);
if (speed < 0) {
error_set(errp, QERR_INVALID_PARAMETER, "speed");
return;
}
ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
}
static void backup_iostatus_reset(BlockJob *job)
{
BackupBlockJob *s = container_of(job, BackupBlockJob, common);
bdrv_iostatus_reset(s->target);
}
static const BlockJobDriver backup_job_driver = {
.instance_size = sizeof(BackupBlockJob),
.job_type = BLOCK_JOB_TYPE_BACKUP,
.set_speed = backup_set_speed,
.iostatus_reset = backup_iostatus_reset,
};
static BlockErrorAction backup_error_action(BackupBlockJob *job,
bool read, int error)
{
if (read) {
return block_job_error_action(&job->common, job->common.bs,
job->on_source_error, true, error);
} else {
return block_job_error_action(&job->common, job->target,
job->on_target_error, false, error);
}
}
static void coroutine_fn backup_run(void *opaque)
{
BackupBlockJob *job = opaque;
BlockDriverState *bs = job->common.bs;
BlockDriverState *target = job->target;
BlockdevOnError on_target_error = job->on_target_error;
NotifierWithReturn before_write = {
.notify = backup_before_write_notify,
};
int64_t start, end;
int ret = 0;
QLIST_INIT(&job->inflight_reqs);
qemu_co_rwlock_init(&job->flush_rwlock);
start = 0;
end = DIV_ROUND_UP(job->common.len / BDRV_SECTOR_SIZE,
BACKUP_SECTORS_PER_CLUSTER);
job->bitmap = hbitmap_alloc(end, 0);
bdrv_set_enable_write_cache(target, true);
bdrv_set_on_error(target, on_target_error, on_target_error);
bdrv_iostatus_enable(target);
bdrv_add_before_write_notifier(bs, &before_write);
if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
while (!block_job_is_cancelled(&job->common)) {
/* Yield until the job is cancelled. We just let our before_write
* notify callback service CoW requests. */
job->common.busy = false;
qemu_coroutine_yield();
job->common.busy = true;
}
} else {
/* Both FULL and TOP SYNC_MODE's require copying.. */
for (; start < end; start++) {
bool error_is_read;
if (block_job_is_cancelled(&job->common)) {
break;
}
/* we need to yield so that qemu_aio_flush() returns.
* (without, VM does not reboot)
*/
if (job->common.speed) {
uint64_t delay_ns = ratelimit_calculate_delay(
&job->limit, job->sectors_read);
job->sectors_read = 0;
block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns);
} else {
block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0);
}
if (block_job_is_cancelled(&job->common)) {
break;
}
if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
int i, n;
int alloced = 0;
/* Check to see if these blocks are already in the
* backing file. */
for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) {
/* bdrv_is_allocated() only returns true/false based
* on the first set of sectors it comes across that
* are are all in the same state.
* For that reason we must verify each sector in the
* backup cluster length. We end up copying more than
* needed but at some point that is always the case. */
alloced =
bdrv_is_allocated(bs,
start * BACKUP_SECTORS_PER_CLUSTER + i,
BACKUP_SECTORS_PER_CLUSTER - i, &n);
i += n;
if (alloced == 1) {
break;
}
}
/* If the above loop never found any sectors that are in
* the topmost image, skip this backup. */
if (alloced == 0) {
continue;
}
}
/* FULL sync mode we copy the whole drive. */
ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
BACKUP_SECTORS_PER_CLUSTER, &error_is_read);
if (ret < 0) {
/* Depending on error action, fail now or retry cluster */
BlockErrorAction action =
backup_error_action(job, error_is_read, -ret);
if (action == BLOCK_ERROR_ACTION_REPORT) {
break;
} else {
start--;
continue;
}
}
}
}
notifier_with_return_remove(&before_write);
/* wait until pending backup_do_cow() calls have completed */
qemu_co_rwlock_wrlock(&job->flush_rwlock);
qemu_co_rwlock_unlock(&job->flush_rwlock);
hbitmap_free(job->bitmap);
bdrv_iostatus_disable(target);
bdrv_unref(target);
block_job_completed(&job->common, ret);
}
void backup_start(BlockDriverState *bs, BlockDriverState *target,
int64_t speed, MirrorSyncMode sync_mode,
BlockdevOnError on_source_error,
BlockdevOnError on_target_error,
BlockDriverCompletionFunc *cb, void *opaque,
Error **errp)
{
int64_t len;
assert(bs);
assert(target);
assert(cb);
if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
!bdrv_iostatus_is_enabled(bs)) {
error_set(errp, QERR_INVALID_PARAMETER, "on-source-error");
return;
}
len = bdrv_getlength(bs);
if (len < 0) {
error_setg_errno(errp, -len, "unable to get length for '%s'",
bdrv_get_device_name(bs));
return;
}
BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed,
cb, opaque, errp);
if (!job) {
return;
}
job->on_source_error = on_source_error;
job->on_target_error = on_target_error;
job->target = target;
job->sync_mode = sync_mode;
job->common.len = len;
job->common.co = qemu_coroutine_create(backup_run);
qemu_coroutine_enter(job->common.co, job);
}
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