diff mbox series

[PULL,17/54] qcow2: Switch qcow2_measure() to byte-based iteration

Message ID 20171006155422.10135-18-kwolf@redhat.com
State New
Headers show
Series [PULL,01/54] block: Typo fix in copy_on_readv() | expand

Commit Message

Kevin Wolf Oct. 6, 2017, 3:53 p.m. UTC 
From: Eric Blake <eblake@redhat.com>

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: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)
diff mbox series

Patch

diff --git a/block/qcow2.c b/block/qcow2.c
index 970006fc1d..b8da8ca105 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -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;
                 }
             }
         }