[Qemu-devel] [PATCH v7 11/20] dirty-bitmap: Change bdrv_dirty_iter_next() to report byte offset

[Eric Blake <eblake@redhat.com>]

Thanks to recent cleanups, most callers were scaling a return value
of sectors into bytes (the exception, in qcow2-bitmap, will be
converted to byte-based iteration later).  Update the interface to
do the scaling internally instead.

In qcow2-bitmap, the code was specifically checking for an error
to be -1; it is more robust to treat all negative values as an
error, but at the same time it is also easy enough to ensure we
return -1 (and not -512) on error.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v7: return -1, not -512; and fix qcow2-bitmap to check all negatives [Kevin]
v5-v6: no change
v4: rebase to persistent bitmap
v3: no change
v2: no change
---
 block/backup.c       | 2 +-
 block/dirty-bitmap.c | 3 ++-
 block/mirror.c       | 8 ++++----
 block/qcow2-bitmap.c | 2 +-
 4 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/block/backup.c b/block/backup.c
index ac9c018717..06ddbfd03d 100644
--- a/block/backup.c
+++ b/block/backup.c
@@ -375,7 +375,7 @@ static int coroutine_fn backup_run_incremental(BackupBlockJob *job)
     dbi = bdrv_dirty_iter_new(job->sync_bitmap);

     /* Find the next dirty sector(s) */
-    while ((offset = bdrv_dirty_iter_next(dbi) * BDRV_SECTOR_SIZE) >= 0) {
+    while ((offset = bdrv_dirty_iter_next(dbi)) >= 0) {
         cluster = offset / job->cluster_size;

         /* Fake progress updates for any clusters we skipped */
diff --git a/block/dirty-bitmap.c b/block/dirty-bitmap.c
index d50c46621d..49229fd501 100644
--- a/block/dirty-bitmap.c
+++ b/block/dirty-bitmap.c
@@ -508,7 +508,8 @@ void bdrv_dirty_iter_free(BdrvDirtyBitmapIter *iter)

 int64_t bdrv_dirty_iter_next(BdrvDirtyBitmapIter *iter)
 {
-    return hbitmap_iter_next(&iter->hbi);
+    int64_t ret = hbitmap_iter_next(&iter->hbi);
+    return ret < 0 ? -1 : ret * BDRV_SECTOR_SIZE;
 }

 /* Called within bdrv_dirty_bitmap_lock..unlock */
diff --git a/block/mirror.c b/block/mirror.c
index 0b063b3c20..77bf5aa3a4 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -336,10 +336,10 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
     int max_io_bytes = MAX(s->buf_size / MAX_IN_FLIGHT, MAX_IO_BYTES);

     bdrv_dirty_bitmap_lock(s->dirty_bitmap);
-    offset = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE;
+    offset = bdrv_dirty_iter_next(s->dbi);
     if (offset < 0) {
         bdrv_set_dirty_iter(s->dbi, 0);
-        offset = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE;
+        offset = bdrv_dirty_iter_next(s->dbi);
         trace_mirror_restart_iter(s, bdrv_get_dirty_count(s->dirty_bitmap) *
                                   BDRV_SECTOR_SIZE);
         assert(offset >= 0);
@@ -370,11 +370,11 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
             break;
         }

-        next_dirty = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE;
+        next_dirty = bdrv_dirty_iter_next(s->dbi);
         if (next_dirty > next_offset || next_dirty < 0) {
             /* The bitmap iterator's cache is stale, refresh it */
             bdrv_set_dirty_iter(s->dbi, next_offset);
-            next_dirty = bdrv_dirty_iter_next(s->dbi) * BDRV_SECTOR_SIZE;
+            next_dirty = bdrv_dirty_iter_next(s->dbi);
         }
         assert(next_dirty == next_offset);
         nb_chunks++;
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c
index 44329fc74f..b09010b1d3 100644
--- a/block/qcow2-bitmap.c
+++ b/block/qcow2-bitmap.c
@@ -1109,7 +1109,7 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs,
     sbc = limit >> BDRV_SECTOR_BITS;
     assert(DIV_ROUND_UP(bm_size, limit) == tb_size);

-    while ((sector = bdrv_dirty_iter_next(dbi)) != -1) {
+    while ((sector = bdrv_dirty_iter_next(dbi) >> BDRV_SECTOR_BITS) >= 0) {
         uint64_t cluster = sector / sbc;
         uint64_t end, write_size;
         int64_t off;
-- 
2.13.5