Commit ee5306d0 authored by Fam Zheng's avatar Fam Zheng Committed by Stefan Hajnoczi
Browse files

qemu-img: Convert with copy offloading 



The new blk_co_copy_range interface offers a more efficient way in the
case of network based storage. Make use of it to allow faster convert
operation.

Since copy offloading cannot do zero detection ('-S') and compression
(-c), only try it when these options are not used.

Signed-off-by: default avatarFam Zheng <famz@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
Message-id: 20180601092648.24614-11-famz@redhat.com
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent b5679fa4

qemu-img.c

+48 −2
Original line number Diff line number Diff line
@@ -1547,6 +1547,7 @@ typedef struct ImgConvertState { 
    bool compressed;

    bool target_has_backing;

    bool wr_in_order;

    bool copy_range;

    int min_sparse;

    size_t cluster_sectors;

    size_t buf_sectors;
@@ -1740,6 +1741,37 @@ static int coroutine_fn convert_co_write(ImgConvertState *s, int64_t sector_num, 
    return 0;

}



static int coroutine_fn convert_co_copy_range(ImgConvertState *s, int64_t sector_num,

                                              int nb_sectors)

{

    int n, ret;



    while (nb_sectors > 0) {

        BlockBackend *blk;

        int src_cur;

        int64_t bs_sectors, src_cur_offset;

        int64_t offset;



        convert_select_part(s, sector_num, &src_cur, &src_cur_offset);

        offset = (sector_num - src_cur_offset) << BDRV_SECTOR_BITS;

        blk = s->src[src_cur];

        bs_sectors = s->src_sectors[src_cur];



        n = MIN(nb_sectors, bs_sectors - (sector_num - src_cur_offset));



        ret = blk_co_copy_range(blk, offset, s->target,

                                sector_num << BDRV_SECTOR_BITS,

                                n << BDRV_SECTOR_BITS, 0);

        if (ret < 0) {

            return ret;

        }



        sector_num += n;

        nb_sectors -= n;

    }

    return 0;

}



static void coroutine_fn convert_co_do_copy(void *opaque)

{

    ImgConvertState *s = opaque;
@@ -1762,6 +1794,7 @@ static void coroutine_fn convert_co_do_copy(void *opaque) 
        int n;

        int64_t sector_num;

        enum ImgConvertBlockStatus status;

        bool copy_range;



        qemu_co_mutex_lock(&s->lock);

        if (s->ret != -EINPROGRESS || s->sector_num >= s->total_sectors) {
@@ -1791,7 +1824,9 @@ static void coroutine_fn convert_co_do_copy(void *opaque) 
                                        s->allocated_sectors, 0);

        }



        if (status == BLK_DATA) {

retry:

        copy_range = s->copy_range && s->status == BLK_DATA;

        if (status == BLK_DATA && !copy_range) {

            ret = convert_co_read(s, sector_num, n, buf);

            if (ret < 0) {

                error_report("error while reading sector %" PRId64
@@ -1813,7 +1848,15 @@ static void coroutine_fn convert_co_do_copy(void *opaque) 
        }



        if (s->ret == -EINPROGRESS) {

            if (copy_range) {

                ret = convert_co_copy_range(s, sector_num, n);

                if (ret) {

                    s->copy_range = false;

                    goto retry;

                }

            } else {

                ret = convert_co_write(s, sector_num, n, buf, status);

            }

            if (ret < 0) {

                error_report("error while writing sector %" PRId64

                             ": %s", sector_num, strerror(-ret));
@@ -1936,6 +1979,7 @@ static int img_convert(int argc, char **argv) 
    ImgConvertState s = (ImgConvertState) {

        /* Need at least 4k of zeros for sparse detection */

        .min_sparse         = 8,

        .copy_range         = true,

        .buf_sectors        = IO_BUF_SIZE / BDRV_SECTOR_SIZE,

        .wr_in_order        = true,

        .num_coroutines     = 8,
@@ -1976,6 +2020,7 @@ static int img_convert(int argc, char **argv) 
            break;

        case 'c':

            s.compressed = true;

            s.copy_range = false;

            break;

        case 'o':

            if (!is_valid_option_list(optarg)) {
@@ -2017,6 +2062,7 @@ static int img_convert(int argc, char **argv) 
            }



            s.min_sparse = sval / BDRV_SECTOR_SIZE;

            s.copy_range = false;

            break;

        }

        case 'p':