Commit b85ee453 authored by Eric Blake's avatar Eric Blake Committed by Kevin Wolf
Browse files

qcow2: Switch qcow2_measure() to byte-based iteration 



This is new code, but it is easier to read if it makes passes over
the image using bytes rather than sectors (and will get easier in
the future when bdrv_get_block_status is converted to byte-based).

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarJohn Snow <jsnow@redhat.com>
Reviewed-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarFam Zheng <famz@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 23ca459a

block/qcow2.c

+10 −12
Original line number Diff line number Diff line
@@ -3673,20 +3673,19 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs, 
             */

            required = virtual_size;

        } else {

            int cluster_sectors = cluster_size / BDRV_SECTOR_SIZE;

            int64_t sector_num;

            int64_t offset;

            int pnum = 0;



            for (sector_num = 0;

                 sector_num < ssize / BDRV_SECTOR_SIZE;

                 sector_num += pnum) {

                int nb_sectors = MIN(ssize / BDRV_SECTOR_SIZE - sector_num,

                                     BDRV_REQUEST_MAX_SECTORS);

            for (offset = 0; offset < ssize;

                 offset += pnum * BDRV_SECTOR_SIZE) {

                int nb_sectors = MIN(ssize - offset,

                                     BDRV_REQUEST_MAX_BYTES) / BDRV_SECTOR_SIZE;

                BlockDriverState *file;

                int64_t ret;



                ret = bdrv_get_block_status_above(in_bs, NULL,

                                                  sector_num, nb_sectors,

                                                  offset >> BDRV_SECTOR_BITS,

                                                  nb_sectors,

                                                  &pnum, &file);

                if (ret < 0) {

                    error_setg_errno(&local_err, -ret,
@@ -3699,12 +3698,11 @@ static BlockMeasureInfo *qcow2_measure(QemuOpts *opts, BlockDriverState *in_bs, 
                } else if ((ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED)) ==

                           (BDRV_BLOCK_DATA | BDRV_BLOCK_ALLOCATED)) {

                    /* Extend pnum to end of cluster for next iteration */

                    pnum = ROUND_UP(sector_num + pnum, cluster_sectors) -

                           sector_num;

                    pnum = (ROUND_UP(offset + pnum * BDRV_SECTOR_SIZE,

                                 cluster_size) - offset) >> BDRV_SECTOR_BITS;



                    /* Count clusters we've seen */

                    required += (sector_num % cluster_sectors + pnum) *

                                BDRV_SECTOR_SIZE;

                    required += offset % cluster_size + pnum * BDRV_SECTOR_SIZE;

                }

            }

        }