[mirror_qemu.git] / block / backup.c

/*
 * 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 "qapi/qmp/qerror.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;
    /* bitmap for sync=incremental */
    BdrvDirtyBitmap *sync_bitmap;
    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,
                                      bool is_write_notifier)
{
    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);

        if (is_write_notifier) {
            ret = bdrv_co_no_copy_on_readv(bs,
                                           start * BACKUP_SECTORS_PER_CLUSTER,
                                           n, &bounce_qiov);
        } else {
            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, true);
}

static void backup_set_speed(BlockJob *job, int64_t speed, Error **errp)
{
    BackupBlockJob *s = container_of(job, BackupBlockJob, common);

    if (speed < 0) {
        error_setg(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);
    }
}

typedef struct {
    int ret;
} BackupCompleteData;

static void backup_complete(BlockJob *job, void *opaque)
{
    BackupBlockJob *s = container_of(job, BackupBlockJob, common);
    BackupCompleteData *data = opaque;

    bdrv_unref(s->target);

    block_job_completed(job, data->ret);
    g_free(data);
}

static bool coroutine_fn yield_and_check(BackupBlockJob *job)
{
    if (block_job_is_cancelled(&job->common)) {
        return true;
    }

    /* we need to yield so that bdrv_drain_all() 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)) {
        return true;
    }

    return false;
}

static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
{
    bool error_is_read;
    int ret = 0;
    int clusters_per_iter;
    uint32_t granularity;
    int64_t sector;
    int64_t cluster;
    int64_t end;
    int64_t last_cluster = -1;
    BlockDriverState *bs = job->common.bs;
    HBitmapIter hbi;

    granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
    clusters_per_iter = MAX((granularity / BACKUP_CLUSTER_SIZE), 1);
    bdrv_dirty_iter_init(job->sync_bitmap, &hbi);

    /* Find the next dirty sector(s) */
    while ((sector = hbitmap_iter_next(&hbi)) != -1) {
        cluster = sector / BACKUP_SECTORS_PER_CLUSTER;

        /* Fake progress updates for any clusters we skipped */
        if (cluster != last_cluster + 1) {
            job->common.offset += ((cluster - last_cluster - 1) *
                                   BACKUP_CLUSTER_SIZE);
        }

        for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
            do {
                if (yield_and_check(job)) {
                    return ret;
                }
                ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
                                    BACKUP_SECTORS_PER_CLUSTER, &error_is_read,
                                    false);
                if ((ret < 0) &&
                    backup_error_action(job, error_is_read, -ret) ==
                    BLOCK_ERROR_ACTION_REPORT) {
                    return ret;
                }
            } while (ret < 0);
        }

        /* If the bitmap granularity is smaller than the backup granularity,
         * we need to advance the iterator pointer to the next cluster. */
        if (granularity < BACKUP_CLUSTER_SIZE) {
            bdrv_set_dirty_iter(&hbi, cluster * BACKUP_SECTORS_PER_CLUSTER);
        }

        last_cluster = cluster - 1;
    }

    /* Play some final catchup with the progress meter */
    end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
    if (last_cluster + 1 < end) {
        job->common.offset += ((end - last_cluster - 1) * BACKUP_CLUSTER_SIZE);
    }

    return ret;
}

static void coroutine_fn backup_run(void *opaque)
{
    BackupBlockJob *job = opaque;
    BackupCompleteData *data;
    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, BACKUP_CLUSTER_SIZE);

    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 if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
        ret = backup_run_incremental(job);
    } else {
        /* Both FULL and TOP SYNC_MODE's require copying.. */
        for (; start < end; start++) {
            bool error_is_read;
            if (yield_and_check(job)) {
                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 || n == 0) {
                        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, false);
            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);

    if (job->sync_bitmap) {
        BdrvDirtyBitmap *bm;
        if (ret < 0 || block_job_is_cancelled(&job->common)) {
            /* Merge the successor back into the parent, delete nothing. */
            bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL);
            assert(bm);
        } else {
            /* Everything is fine, delete this bitmap and install the backup. */
            bm = bdrv_dirty_bitmap_abdicate(bs, job->sync_bitmap, NULL);
            assert(bm);
        }
    }
    hbitmap_free(job->bitmap);

    bdrv_iostatus_disable(target);
    bdrv_op_unblock_all(target, job->common.blocker);

    data = g_malloc(sizeof(*data));
    data->ret = ret;
    block_job_defer_to_main_loop(&job->common, backup_complete, data);
}

void backup_start(BlockDriverState *bs, BlockDriverState *target,
                  int64_t speed, MirrorSyncMode sync_mode,
                  BdrvDirtyBitmap *sync_bitmap,
                  BlockdevOnError on_source_error,
                  BlockdevOnError on_target_error,
                  BlockCompletionFunc *cb, void *opaque,
                  Error **errp)
{
    int64_t len;

    assert(bs);
    assert(target);
    assert(cb);

    if (bs == target) {
        error_setg(errp, "Source and target cannot be the same");
        return;
    }

    if ((on_source_error == BLOCKDEV_ON_ERROR_STOP ||
         on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
        !bdrv_iostatus_is_enabled(bs)) {
        error_setg(errp, QERR_INVALID_PARAMETER, "on-source-error");
        return;
    }

    if (!bdrv_is_inserted(bs)) {
        error_setg(errp, "Device is not inserted: %s",
                   bdrv_get_device_name(bs));
        return;
    }

    if (!bdrv_is_inserted(target)) {
        error_setg(errp, "Device is not inserted: %s",
                   bdrv_get_device_name(target));
        return;
    }

    if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
        return;
    }

    if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
        return;
    }

    if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
        if (!sync_bitmap) {
            error_setg(errp, "must provide a valid bitmap name for "
                             "\"incremental\" sync mode");
            return;
        }

        /* Create a new bitmap, and freeze/disable this one. */
        if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) {
            return;
        }
    } else if (sync_bitmap) {
        error_setg(errp,
                   "a sync_bitmap was provided to backup_run, "
                   "but received an incompatible sync_mode (%s)",
                   MirrorSyncMode_lookup[sync_mode]);
        return;
    }

    len = bdrv_getlength(bs);
    if (len < 0) {
        error_setg_errno(errp, -len, "unable to get length for '%s'",
                         bdrv_get_device_name(bs));
        goto error;
    }

    BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed,
                                           cb, opaque, errp);
    if (!job) {
        goto error;
    }

    bdrv_op_block_all(target, job->common.blocker);

    job->on_source_error = on_source_error;
    job->on_target_error = on_target_error;
    job->target = target;
    job->sync_mode = sync_mode;
    job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
                       sync_bitmap : NULL;
    job->common.len = len;
    job->common.co = qemu_coroutine_create(backup_run);
    qemu_coroutine_enter(job->common.co, job);
    return;

 error:
    if (sync_bitmap) {
        bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
    }
}
Commit	Line	Data
98d2c6f2 DM	1	/*
	2	* QEMU backup
	3	*
	4	* Copyright (C) 2013 Proxmox Server Solutions
	5	*
	6	* Authors:
	7	* Dietmar Maurer (dietmar@proxmox.com)
	8	*
	9	* This work is licensed under the terms of the GNU GPL, version 2 or later.
	10	* See the COPYING file in the top-level directory.
	11	*
	12	*/
	13
	14	#include <stdio.h>
	15	#include <errno.h>
	16	#include <unistd.h>
	17
	18	#include "trace.h"
	19	#include "block/block.h"
	20	#include "block/block_int.h"
	21	#include "block/blockjob.h"
cc7a8ea7	22	#include "qapi/qmp/qerror.h"
98d2c6f2 DM	23	#include "qemu/ratelimit.h"
	24
	25	#define BACKUP_CLUSTER_BITS 16
	26	#define BACKUP_CLUSTER_SIZE (1 << BACKUP_CLUSTER_BITS)
	27	#define BACKUP_SECTORS_PER_CLUSTER (BACKUP_CLUSTER_SIZE / BDRV_SECTOR_SIZE)
	28
	29	#define SLICE_TIME 100000000ULL /* ns */
	30
	31	typedef struct CowRequest {
	32	int64_t start;
	33	int64_t end;
	34	QLIST_ENTRY(CowRequest) list;
	35	CoQueue wait_queue; /* coroutines blocked on this request */
	36	} CowRequest;
	37
	38	typedef struct BackupBlockJob {
	39	BlockJob common;
	40	BlockDriverState *target;
4b80ab2b	41	/* bitmap for sync=incremental */
d58d8453	42	BdrvDirtyBitmap *sync_bitmap;
fc5d3f84	43	MirrorSyncMode sync_mode;
98d2c6f2 DM	44	RateLimit limit;
	45	BlockdevOnError on_source_error;
	46	BlockdevOnError on_target_error;
	47	CoRwlock flush_rwlock;
	48	uint64_t sectors_read;
	49	HBitmap *bitmap;
	50	QLIST_HEAD(, CowRequest) inflight_reqs;
	51	} BackupBlockJob;
	52
	53	/* See if in-flight requests overlap and wait for them to complete */
	54	static void coroutine_fn wait_for_overlapping_requests(BackupBlockJob *job,
	55	int64_t start,
	56	int64_t end)
	57	{
	58	CowRequest *req;
	59	bool retry;
	60
	61	do {
	62	retry = false;
	63	QLIST_FOREACH(req, &job->inflight_reqs, list) {
	64	if (end > req->start && start < req->end) {
	65	qemu_co_queue_wait(&req->wait_queue);
	66	retry = true;
	67	break;
	68	}
	69	}
	70	} while (retry);
	71	}
	72
	73	/* Keep track of an in-flight request */
	74	static void cow_request_begin(CowRequest req, BackupBlockJob job,
	75	int64_t start, int64_t end)
	76	{
	77	req->start = start;
	78	req->end = end;
	79	qemu_co_queue_init(&req->wait_queue);
	80	QLIST_INSERT_HEAD(&job->inflight_reqs, req, list);
	81	}
	82
	83	/* Forget about a completed request */
	84	static void cow_request_end(CowRequest *req)
	85	{
	86	QLIST_REMOVE(req, list);
	87	qemu_co_queue_restart_all(&req->wait_queue);
	88	}
	89
	90	static int coroutine_fn backup_do_cow(BlockDriverState *bs,
	91	int64_t sector_num, int nb_sectors,
06c3916b WC	92	bool *error_is_read,
06c3916b WC	93	bool is_write_notifier)
98d2c6f2 DM	94	{
	95	BackupBlockJob job = (BackupBlockJob )bs->job;
	96	CowRequest cow_request;
	97	struct iovec iov;
	98	QEMUIOVector bounce_qiov;
	99	void *bounce_buffer = NULL;
	100	int ret = 0;
	101	int64_t start, end;
	102	int n;
	103
	104	qemu_co_rwlock_rdlock(&job->flush_rwlock);
	105
	106	start = sector_num / BACKUP_SECTORS_PER_CLUSTER;
	107	end = DIV_ROUND_UP(sector_num + nb_sectors, BACKUP_SECTORS_PER_CLUSTER);
	108
	109	trace_backup_do_cow_enter(job, start, sector_num, nb_sectors);
	110
	111	wait_for_overlapping_requests(job, start, end);
	112	cow_request_begin(&cow_request, job, start, end);
	113
	114	for (; start < end; start++) {
	115	if (hbitmap_get(job->bitmap, start)) {
	116	trace_backup_do_cow_skip(job, start);
	117	continue; /* already copied */
	118	}
	119
	120	trace_backup_do_cow_process(job, start);
	121
	122	n = MIN(BACKUP_SECTORS_PER_CLUSTER,
	123	job->common.len / BDRV_SECTOR_SIZE -
	124	start * BACKUP_SECTORS_PER_CLUSTER);
	125
	126	if (!bounce_buffer) {
	127	bounce_buffer = qemu_blockalign(bs, BACKUP_CLUSTER_SIZE);
	128	}
	129	iov.iov_base = bounce_buffer;
	130	iov.iov_len = n * BDRV_SECTOR_SIZE;
	131	qemu_iovec_init_external(&bounce_qiov, &iov, 1);
	132
06c3916b WC	133	if (is_write_notifier) {
	134	ret = bdrv_co_no_copy_on_readv(bs,
	135	start * BACKUP_SECTORS_PER_CLUSTER,
	136	n, &bounce_qiov);
	137	} else {
	138	ret = bdrv_co_readv(bs, start * BACKUP_SECTORS_PER_CLUSTER, n,
	139	&bounce_qiov);
	140	}
98d2c6f2 DM	141	if (ret < 0) {
	142	trace_backup_do_cow_read_fail(job, start, ret);
	143	if (error_is_read) {
	144	*error_is_read = true;
	145	}
	146	goto out;
	147	}
	148
	149	if (buffer_is_zero(iov.iov_base, iov.iov_len)) {
	150	ret = bdrv_co_write_zeroes(job->target,
aa7bfbff	151	start * BACKUP_SECTORS_PER_CLUSTER,
d32f35cb	152	n, BDRV_REQ_MAY_UNMAP);
98d2c6f2 DM	153	} else {
	154	ret = bdrv_co_writev(job->target,
	155	start * BACKUP_SECTORS_PER_CLUSTER, n,
	156	&bounce_qiov);
	157	}
	158	if (ret < 0) {
	159	trace_backup_do_cow_write_fail(job, start, ret);
	160	if (error_is_read) {
	161	*error_is_read = false;
	162	}
	163	goto out;
	164	}
	165
	166	hbitmap_set(job->bitmap, start, 1);
	167
	168	/* Publish progress, guest I/O counts as progress too. Note that the
	169	* offset field is an opaque progress value, it is not a disk offset.
	170	*/
	171	job->sectors_read += n;
	172	job->common.offset += n * BDRV_SECTOR_SIZE;
	173	}
	174
	175	out:
	176	if (bounce_buffer) {
	177	qemu_vfree(bounce_buffer);
	178	}
	179
	180	cow_request_end(&cow_request);
	181
	182	trace_backup_do_cow_return(job, sector_num, nb_sectors, ret);
	183
	184	qemu_co_rwlock_unlock(&job->flush_rwlock);
	185
	186	return ret;
	187	}
	188
	189	static int coroutine_fn backup_before_write_notify(
	190	NotifierWithReturn *notifier,
	191	void *opaque)
	192	{
	193	BdrvTrackedRequest *req = opaque;
793ed47a KW	194	int64_t sector_num = req->offset >> BDRV_SECTOR_BITS;
793ed47a KW	195	int nb_sectors = req->bytes >> BDRV_SECTOR_BITS;
98d2c6f2	196
793ed47a KW	197	assert((req->offset & (BDRV_SECTOR_SIZE - 1)) == 0);
	198	assert((req->bytes & (BDRV_SECTOR_SIZE - 1)) == 0);
	199
06c3916b	200	return backup_do_cow(req->bs, sector_num, nb_sectors, NULL, true);
98d2c6f2 DM	201	}
	202
	203	static void backup_set_speed(BlockJob job, int64_t speed, Error *errp)
	204	{
	205	BackupBlockJob *s = container_of(job, BackupBlockJob, common);
	206
	207	if (speed < 0) {
c6bd8c70	208	error_setg(errp, QERR_INVALID_PARAMETER, "speed");
98d2c6f2 DM	209	return;
	210	}
	211	ratelimit_set_speed(&s->limit, speed / BDRV_SECTOR_SIZE, SLICE_TIME);
	212	}
	213
	214	static void backup_iostatus_reset(BlockJob *job)
	215	{
	216	BackupBlockJob *s = container_of(job, BackupBlockJob, common);
	217
	218	bdrv_iostatus_reset(s->target);
	219	}
	220
3fc4b10a	221	static const BlockJobDriver backup_job_driver = {
98d2c6f2	222	.instance_size = sizeof(BackupBlockJob),
79e14bf7	223	.job_type = BLOCK_JOB_TYPE_BACKUP,
98d2c6f2 DM	224	.set_speed = backup_set_speed,
	225	.iostatus_reset = backup_iostatus_reset,
	226	};
	227
	228	static BlockErrorAction backup_error_action(BackupBlockJob *job,
	229	bool read, int error)
	230	{
	231	if (read) {
	232	return block_job_error_action(&job->common, job->common.bs,
	233	job->on_source_error, true, error);
	234	} else {
	235	return block_job_error_action(&job->common, job->target,
	236	job->on_target_error, false, error);
	237	}
	238	}
	239
761731b1 SH	240	typedef struct {
	241	int ret;
	242	} BackupCompleteData;
	243
	244	static void backup_complete(BlockJob job, void opaque)
	245	{
	246	BackupBlockJob *s = container_of(job, BackupBlockJob, common);
	247	BackupCompleteData *data = opaque;
	248
	249	bdrv_unref(s->target);
	250
	251	block_job_completed(job, data->ret);
	252	g_free(data);
	253	}
	254
d58d8453 JS	255	static bool coroutine_fn yield_and_check(BackupBlockJob *job)
	256	{
	257	if (block_job_is_cancelled(&job->common)) {
	258	return true;
	259	}
	260
	261	/* we need to yield so that bdrv_drain_all() returns.
	262	* (without, VM does not reboot)
	263	*/
	264	if (job->common.speed) {
	265	uint64_t delay_ns = ratelimit_calculate_delay(&job->limit,
	266	job->sectors_read);
	267	job->sectors_read = 0;
	268	block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, delay_ns);
	269	} else {
	270	block_job_sleep_ns(&job->common, QEMU_CLOCK_REALTIME, 0);
	271	}
	272
	273	if (block_job_is_cancelled(&job->common)) {
	274	return true;
	275	}
	276
	277	return false;
	278	}
	279
	280	static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
	281	{
	282	bool error_is_read;
	283	int ret = 0;
	284	int clusters_per_iter;
	285	uint32_t granularity;
	286	int64_t sector;
	287	int64_t cluster;
	288	int64_t end;
	289	int64_t last_cluster = -1;
	290	BlockDriverState *bs = job->common.bs;
	291	HBitmapIter hbi;
	292
	293	granularity = bdrv_dirty_bitmap_granularity(job->sync_bitmap);
	294	clusters_per_iter = MAX((granularity / BACKUP_CLUSTER_SIZE), 1);
20dca810	295	bdrv_dirty_iter_init(job->sync_bitmap, &hbi);
d58d8453 JS	296
	297	/* Find the next dirty sector(s) */
	298	while ((sector = hbitmap_iter_next(&hbi)) != -1) {
	299	cluster = sector / BACKUP_SECTORS_PER_CLUSTER;
	300
	301	/* Fake progress updates for any clusters we skipped */
	302	if (cluster != last_cluster + 1) {
	303	job->common.offset += ((cluster - last_cluster - 1) *
	304	BACKUP_CLUSTER_SIZE);
	305	}
	306
	307	for (end = cluster + clusters_per_iter; cluster < end; cluster++) {
	308	do {
	309	if (yield_and_check(job)) {
	310	return ret;
	311	}
	312	ret = backup_do_cow(bs, cluster * BACKUP_SECTORS_PER_CLUSTER,
06c3916b WC	313	BACKUP_SECTORS_PER_CLUSTER, &error_is_read,
06c3916b WC	314	false);
d58d8453 JS	315	if ((ret < 0) &&
	316	backup_error_action(job, error_is_read, -ret) ==
	317	BLOCK_ERROR_ACTION_REPORT) {
	318	return ret;
	319	}
	320	} while (ret < 0);
	321	}
	322
	323	/* If the bitmap granularity is smaller than the backup granularity,
	324	* we need to advance the iterator pointer to the next cluster. */
	325	if (granularity < BACKUP_CLUSTER_SIZE) {
	326	bdrv_set_dirty_iter(&hbi, cluster * BACKUP_SECTORS_PER_CLUSTER);
	327	}
	328
	329	last_cluster = cluster - 1;
	330	}
	331
	332	/* Play some final catchup with the progress meter */
	333	end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
	334	if (last_cluster + 1 < end) {
	335	job->common.offset += ((end - last_cluster - 1) * BACKUP_CLUSTER_SIZE);
	336	}
	337
	338	return ret;
	339	}
	340
98d2c6f2 DM	341	static void coroutine_fn backup_run(void *opaque)
	342	{
	343	BackupBlockJob *job = opaque;
761731b1	344	BackupCompleteData *data;
98d2c6f2 DM	345	BlockDriverState *bs = job->common.bs;
	346	BlockDriverState *target = job->target;
	347	BlockdevOnError on_target_error = job->on_target_error;
	348	NotifierWithReturn before_write = {
	349	.notify = backup_before_write_notify,
	350	};
	351	int64_t start, end;
	352	int ret = 0;
	353
	354	QLIST_INIT(&job->inflight_reqs);
	355	qemu_co_rwlock_init(&job->flush_rwlock);
	356
	357	start = 0;
d58d8453	358	end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE);
98d2c6f2 DM	359
	360	job->bitmap = hbitmap_alloc(end, 0);
	361
	362	bdrv_set_enable_write_cache(target, true);
	363	bdrv_set_on_error(target, on_target_error, on_target_error);
	364	bdrv_iostatus_enable(target);
	365
	366	bdrv_add_before_write_notifier(bs, &before_write);
	367
fc5d3f84 IM	368	if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
	369	while (!block_job_is_cancelled(&job->common)) {
	370	/* Yield until the job is cancelled. We just let our before_write
	371	* notify callback service CoW requests. */
	372	job->common.busy = false;
	373	qemu_coroutine_yield();
	374	job->common.busy = true;
98d2c6f2	375	}
4b80ab2b	376	} else if (job->sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
d58d8453	377	ret = backup_run_incremental(job);
fc5d3f84 IM	378	} else {
	379	/* Both FULL and TOP SYNC_MODE's require copying.. */
	380	for (; start < end; start++) {
	381	bool error_is_read;
d58d8453	382	if (yield_and_check(job)) {
98d2c6f2	383	break;
fc5d3f84 IM	384	}
	385
	386	if (job->sync_mode == MIRROR_SYNC_MODE_TOP) {
	387	int i, n;
	388	int alloced = 0;
	389
	390	/* Check to see if these blocks are already in the
	391	* backing file. */
	392
	393	for (i = 0; i < BACKUP_SECTORS_PER_CLUSTER;) {
bdad13b9	394	/* bdrv_is_allocated() only returns true/false based
4c293dc6	395	* on the first set of sectors it comes across that
fc5d3f84 IM	396	* are are all in the same state.
	397	* For that reason we must verify each sector in the
	398	* backup cluster length. We end up copying more than
	399	* needed but at some point that is always the case. */
	400	alloced =
bdad13b9	401	bdrv_is_allocated(bs,
fc5d3f84 IM	402	start * BACKUP_SECTORS_PER_CLUSTER + i,
	403	BACKUP_SECTORS_PER_CLUSTER - i, &n);
	404	i += n;
	405
d40593dd	406	if (alloced == 1 \|\| n == 0) {
fc5d3f84 IM	407	break;
	408	}
	409	}
	410
	411	/* If the above loop never found any sectors that are in
	412	* the topmost image, skip this backup. */
	413	if (alloced == 0) {
	414	continue;
	415	}
	416	}
	417	/* FULL sync mode we copy the whole drive. */
	418	ret = backup_do_cow(bs, start * BACKUP_SECTORS_PER_CLUSTER,
06c3916b	419	BACKUP_SECTORS_PER_CLUSTER, &error_is_read, false);
fc5d3f84 IM	420	if (ret < 0) {
	421	/* Depending on error action, fail now or retry cluster */
	422	BlockErrorAction action =
	423	backup_error_action(job, error_is_read, -ret);
a589569f	424	if (action == BLOCK_ERROR_ACTION_REPORT) {
fc5d3f84 IM	425	break;
	426	} else {
	427	start--;
	428	continue;
	429	}
98d2c6f2 DM	430	}
	431	}
	432	}
	433
	434	notifier_with_return_remove(&before_write);
	435
	436	/* wait until pending backup_do_cow() calls have completed */
	437	qemu_co_rwlock_wrlock(&job->flush_rwlock);
	438	qemu_co_rwlock_unlock(&job->flush_rwlock);
	439
d58d8453 JS	440	if (job->sync_bitmap) {
d58d8453 JS	441	BdrvDirtyBitmap *bm;
17d9716d	442	if (ret < 0 \|\| block_job_is_cancelled(&job->common)) {
d58d8453 JS	443	/* Merge the successor back into the parent, delete nothing. */
	444	bm = bdrv_reclaim_dirty_bitmap(bs, job->sync_bitmap, NULL);
	445	assert(bm);
	446	} else {
	447	/* Everything is fine, delete this bitmap and install the backup. */
	448	bm = bdrv_dirty_bitmap_abdicate(bs, job->sync_bitmap, NULL);
	449	assert(bm);
	450	}
	451	}
98d2c6f2 DM	452	hbitmap_free(job->bitmap);
	453
	454	bdrv_iostatus_disable(target);
c29c1dd3	455	bdrv_op_unblock_all(target, job->common.blocker);
98d2c6f2	456
761731b1 SH	457	data = g_malloc(sizeof(*data));
	458	data->ret = ret;
	459	block_job_defer_to_main_loop(&job->common, backup_complete, data);
98d2c6f2 DM	460	}
	461
	462	void backup_start(BlockDriverState bs, BlockDriverState target,
fc5d3f84	463	int64_t speed, MirrorSyncMode sync_mode,
d58d8453	464	BdrvDirtyBitmap *sync_bitmap,
98d2c6f2 DM	465	BlockdevOnError on_source_error,
98d2c6f2 DM	466	BlockdevOnError on_target_error,
097310b5	467	BlockCompletionFunc cb, void opaque,
98d2c6f2 DM	468	Error **errp)
	469	{
	470	int64_t len;
	471
	472	assert(bs);
	473	assert(target);
	474	assert(cb);
	475
c29c1dd3 FZ	476	if (bs == target) {
	477	error_setg(errp, "Source and target cannot be the same");
	478	return;
	479	}
	480
98d2c6f2 DM	481	if ((on_source_error == BLOCKDEV_ON_ERROR_STOP \|\|
	482	on_source_error == BLOCKDEV_ON_ERROR_ENOSPC) &&
	483	!bdrv_iostatus_is_enabled(bs)) {
c6bd8c70	484	error_setg(errp, QERR_INVALID_PARAMETER, "on-source-error");
98d2c6f2 DM	485	return;
	486	}
	487
c29c1dd3 FZ	488	if (!bdrv_is_inserted(bs)) {
	489	error_setg(errp, "Device is not inserted: %s",
	490	bdrv_get_device_name(bs));
	491	return;
	492	}
	493
	494	if (!bdrv_is_inserted(target)) {
	495	error_setg(errp, "Device is not inserted: %s",
	496	bdrv_get_device_name(target));
	497	return;
	498	}
	499
	500	if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_BACKUP_SOURCE, errp)) {
	501	return;
	502	}
	503
	504	if (bdrv_op_is_blocked(target, BLOCK_OP_TYPE_BACKUP_TARGET, errp)) {
	505	return;
	506	}
	507
4b80ab2b	508	if (sync_mode == MIRROR_SYNC_MODE_INCREMENTAL) {
d58d8453 JS	509	if (!sync_bitmap) {
d58d8453 JS	510	error_setg(errp, "must provide a valid bitmap name for "
4b80ab2b	511	"\"incremental\" sync mode");
d58d8453 JS	512	return;
	513	}
	514
	515	/* Create a new bitmap, and freeze/disable this one. */
	516	if (bdrv_dirty_bitmap_create_successor(bs, sync_bitmap, errp) < 0) {
	517	return;
	518	}
	519	} else if (sync_bitmap) {
	520	error_setg(errp,
	521	"a sync_bitmap was provided to backup_run, "
	522	"but received an incompatible sync_mode (%s)",
	523	MirrorSyncMode_lookup[sync_mode]);
	524	return;
	525	}
	526
98d2c6f2 DM	527	len = bdrv_getlength(bs);
	528	if (len < 0) {
	529	error_setg_errno(errp, -len, "unable to get length for '%s'",
	530	bdrv_get_device_name(bs));
d58d8453	531	goto error;
98d2c6f2 DM	532	}
98d2c6f2 DM	533
3fc4b10a	534	BackupBlockJob *job = block_job_create(&backup_job_driver, bs, speed,
98d2c6f2 DM	535	cb, opaque, errp);
98d2c6f2 DM	536	if (!job) {
d58d8453	537	goto error;
98d2c6f2 DM	538	}
98d2c6f2 DM	539
c29c1dd3 FZ	540	bdrv_op_block_all(target, job->common.blocker);
c29c1dd3 FZ	541
98d2c6f2 DM	542	job->on_source_error = on_source_error;
	543	job->on_target_error = on_target_error;
	544	job->target = target;
fc5d3f84	545	job->sync_mode = sync_mode;
4b80ab2b	546	job->sync_bitmap = sync_mode == MIRROR_SYNC_MODE_INCREMENTAL ?
d58d8453	547	sync_bitmap : NULL;
98d2c6f2 DM	548	job->common.len = len;
	549	job->common.co = qemu_coroutine_create(backup_run);
	550	qemu_coroutine_enter(job->common.co, job);
d58d8453 JS	551	return;
	552
	553	error:
	554	if (sync_bitmap) {
	555	bdrv_reclaim_dirty_bitmap(bs, sync_bitmap, NULL);
	556	}
98d2c6f2	557	}