Commit 24f833cd authored by Peter Lieven's avatar Peter Lieven Committed by Stefan Hajnoczi
Browse files

qemu-img: round down request length to an aligned sector 



this patch shortens requests to end at an aligned sector so that
the next request starts aligned.

[Squashed Peter's fix for bdrv_get_info() failure discussed on the
mailing list.
--Stefan]

Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarPeter Lieven <pl@kamp.de>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent f2521c90

qemu-img.c

+24 −8
Original line number Diff line number Diff line
@@ -1129,8 +1129,7 @@ out3: 


static int img_convert(int argc, char **argv)

{

    int c, n, n1, bs_n, bs_i, compress, cluster_size,

        cluster_sectors, skip_create;

    int c, n, n1, bs_n, bs_i, compress, cluster_sectors, skip_create;

    int64_t ret = 0;

    int progress = 0, flags;

    const char *fmt, *out_fmt, *cache, *out_baseimg, *out_filename;
@@ -1424,19 +1423,23 @@ static int img_convert(int argc, char **argv) 
        }

    }



    if (compress) {

    cluster_sectors = 0;

    ret = bdrv_get_info(out_bs, &bdi);

    if (ret < 0) {

        if (compress) {

            error_report("could not get block driver info");

            goto out;

        }

        cluster_size = bdi.cluster_size;

        if (cluster_size <= 0 || cluster_size > bufsectors * BDRV_SECTOR_SIZE) {

    } else {

        cluster_sectors = bdi.cluster_size / BDRV_SECTOR_SIZE;

    }



    if (compress) {

        if (cluster_sectors <= 0 || cluster_sectors > bufsectors) {

            error_report("invalid cluster size");

            ret = -1;

            goto out;

        }

        cluster_sectors = cluster_size >> 9;

        sector_num = 0;



        nb_sectors = total_sectors;
@@ -1569,6 +1572,19 @@ static int img_convert(int argc, char **argv) 
            }



            n = MIN(nb_sectors, bufsectors);



            /* round down request length to an aligned sector, but

             * do not bother doing this on short requests. They happen

             * when we found an all-zero area, and the next sector to

             * write will not be sector_num + n. */

            if (cluster_sectors > 0 && n >= cluster_sectors) {

                int64_t next_aligned_sector = (sector_num + n);

                next_aligned_sector -= next_aligned_sector % cluster_sectors;

                if (sector_num + n > next_aligned_sector) {

                    n = next_aligned_sector - sector_num;

                }

            }



            n = MIN(n, bs_sectors - (sector_num - bs_offset));

            n1 = n;