| Message ID | 20170830210542.2153-17-eblake@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | make dirty-bitmap byte-based | expand |
Am 30.08.2017 um 23:05 hat Eric Blake geschrieben: > Now that we have adjusted the majority of the calls this function > makes to be byte-based, it is easier to read the code if it makes > passes over the image using bytes rather than sectors. > > Signed-off-by: Eric Blake <eblake@redhat.com> > Reviewed-by: John Snow <jsnow@redhat.com> > Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > > --- > v5: no change > v4: new patch > --- > block/qcow2-bitmap.c | 26 +++++++++++--------------- > 1 file changed, 11 insertions(+), 15 deletions(-) > > diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c > index b807298484..63d845e35f 100644 > --- a/block/qcow2-bitmap.c > +++ b/block/qcow2-bitmap.c > @@ -1072,10 +1072,9 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs, > { > int ret; > BDRVQcow2State *s = bs->opaque; > - int64_t sector; > - uint64_t limit, sbc; > + int64_t offset; > + uint64_t limit; > uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap); > - uint64_t bm_sectors = DIV_ROUND_UP(bm_size, BDRV_SECTOR_SIZE); > const char *bm_name = bdrv_dirty_bitmap_name(bitmap); > uint8_t *buf = NULL; > BdrvDirtyBitmapIter *dbi; > @@ -1100,18 +1099,17 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs, > dbi = bdrv_dirty_iter_new(bitmap); > buf = g_malloc(s->cluster_size); > limit = bytes_covered_by_bitmap_cluster(s, bitmap); > - sbc = limit >> BDRV_SECTOR_BITS; > assert(DIV_ROUND_UP(bm_size, limit) == tb_size); > > - while ((sector = bdrv_dirty_iter_next(dbi) >> BDRV_SECTOR_BITS) != -1) { > - uint64_t cluster = sector / sbc; > + while ((offset = bdrv_dirty_iter_next(dbi)) != -1) { Don't you have to multiply both sides of the equation? This would be offset != -512, which points out that the previous patch to convert bdrv_dirty_iter_next() to byte-based gave it a really awkward interface. > + uint64_t cluster = offset / limit; > uint64_t end, write_size; > int64_t off; > > - sector = cluster * sbc; > - end = MIN(bm_sectors, sector + sbc); > - write_size = bdrv_dirty_bitmap_serialization_size(bitmap, > - sector * BDRV_SECTOR_SIZE, (end - sector) * BDRV_SECTOR_SIZE); > + offset = cluster * limit; You just had cluster = offset / limit, so in other words, align down offset? If so, this is how it should be written. Kevin
On 09/08/2017 08:27 AM, Kevin Wolf wrote: > Am 30.08.2017 um 23:05 hat Eric Blake geschrieben: >> Now that we have adjusted the majority of the calls this function >> makes to be byte-based, it is easier to read the code if it makes >> passes over the image using bytes rather than sectors. >> >> Signed-off-by: Eric Blake <eblake@redhat.com> >> Reviewed-by: John Snow <jsnow@redhat.com> >> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> >> >> >> - while ((sector = bdrv_dirty_iter_next(dbi) >> BDRV_SECTOR_BITS) != -1) { >> - uint64_t cluster = sector / sbc; >> + while ((offset = bdrv_dirty_iter_next(dbi)) != -1) { > > Don't you have to multiply both sides of the equation? This would be > offset != -512, which points out that the previous patch to convert > bdrv_dirty_iter_next() to byte-based gave it a really awkward interface. I think what I really need to do is change '!= -1' to '< 0', as that's much easier to reason about when scaling is present. > >> + uint64_t cluster = offset / limit; >> uint64_t end, write_size; >> int64_t off; >> >> - sector = cluster * sbc; >> - end = MIN(bm_sectors, sector + sbc); >> - write_size = bdrv_dirty_bitmap_serialization_size(bitmap, >> - sector * BDRV_SECTOR_SIZE, (end - sector) * BDRV_SECTOR_SIZE); >> + offset = cluster * limit; > > You just had cluster = offset / limit, so in other words, align down > offset? If so, this is how it should be written. Thanks for the close reviews; looks like I have enough things to do a respin.
Am 08.09.2017 um 16:09 hat Eric Blake geschrieben: > On 09/08/2017 08:27 AM, Kevin Wolf wrote: > > Am 30.08.2017 um 23:05 hat Eric Blake geschrieben: > >> Now that we have adjusted the majority of the calls this function > >> makes to be byte-based, it is easier to read the code if it makes > >> passes over the image using bytes rather than sectors. > >> > >> Signed-off-by: Eric Blake <eblake@redhat.com> > >> Reviewed-by: John Snow <jsnow@redhat.com> > >> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> > >> > > >> > >> - while ((sector = bdrv_dirty_iter_next(dbi) >> BDRV_SECTOR_BITS) != -1) { > >> - uint64_t cluster = sector / sbc; > >> + while ((offset = bdrv_dirty_iter_next(dbi)) != -1) { > > > > Don't you have to multiply both sides of the equation? This would be > > offset != -512, which points out that the previous patch to convert > > bdrv_dirty_iter_next() to byte-based gave it a really awkward interface. > > I think what I really need to do is change '!= -1' to '< 0', as that's > much easier to reason about when scaling is present. Hm, I think I would prefer a special case for -1 in bdrv_dirty_iter_next() so that it returns -1 after the last entry. Even if you check for < 0, -512 is still an odd return value to signal the end. Though I think after the final patch, we're back to -1 anyway, so it's not that important. Kevin
diff --git a/block/qcow2-bitmap.c b/block/qcow2-bitmap.c index b807298484..63d845e35f 100644 --- a/block/qcow2-bitmap.c +++ b/block/qcow2-bitmap.c @@ -1072,10 +1072,9 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs, { int ret; BDRVQcow2State *s = bs->opaque; - int64_t sector; - uint64_t limit, sbc; + int64_t offset; + uint64_t limit; uint64_t bm_size = bdrv_dirty_bitmap_size(bitmap); - uint64_t bm_sectors = DIV_ROUND_UP(bm_size, BDRV_SECTOR_SIZE); const char *bm_name = bdrv_dirty_bitmap_name(bitmap); uint8_t *buf = NULL; BdrvDirtyBitmapIter *dbi; @@ -1100,18 +1099,17 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs, dbi = bdrv_dirty_iter_new(bitmap); buf = g_malloc(s->cluster_size); limit = bytes_covered_by_bitmap_cluster(s, bitmap); - sbc = limit >> BDRV_SECTOR_BITS; assert(DIV_ROUND_UP(bm_size, limit) == tb_size); - while ((sector = bdrv_dirty_iter_next(dbi) >> BDRV_SECTOR_BITS) != -1) { - uint64_t cluster = sector / sbc; + while ((offset = bdrv_dirty_iter_next(dbi)) != -1) { + uint64_t cluster = offset / limit; uint64_t end, write_size; int64_t off; - sector = cluster * sbc; - end = MIN(bm_sectors, sector + sbc); - write_size = bdrv_dirty_bitmap_serialization_size(bitmap, - sector * BDRV_SECTOR_SIZE, (end - sector) * BDRV_SECTOR_SIZE); + offset = cluster * limit; + end = MIN(bm_size, offset + limit); + write_size = bdrv_dirty_bitmap_serialization_size(bitmap, offset, + end - offset); assert(write_size <= s->cluster_size); off = qcow2_alloc_clusters(bs, s->cluster_size); @@ -1123,9 +1121,7 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs, } tb[cluster] = off; - bdrv_dirty_bitmap_serialize_part(bitmap, buf, - sector * BDRV_SECTOR_SIZE, - (end - sector) * BDRV_SECTOR_SIZE); + bdrv_dirty_bitmap_serialize_part(bitmap, buf, offset, end - offset); if (write_size < s->cluster_size) { memset(buf + write_size, 0, s->cluster_size - write_size); } @@ -1143,11 +1139,11 @@ static uint64_t *store_bitmap_data(BlockDriverState *bs, goto fail; } - if (end >= bm_sectors) { + if (end >= bm_size) { break; } - bdrv_set_dirty_iter(dbi, end * BDRV_SECTOR_SIZE); + bdrv_set_dirty_iter(dbi, end); } *bitmap_table_size = tb_size;