On Tue, Jun 27, 2017 at 02:24:42PM -0500, Eric Blake wrote: > We are gradually converting to byte-based interfaces, as they are > easier to reason about than sector-based. Change the internal > loop iteration of streaming to track by bytes instead of sectors > (although we are still guaranteed that we iterate by steps that > are sector-aligned). > > Signed-off-by: Eric Blake <ebl...@redhat.com> > Reviewed-by: John Snow <js...@redhat.com> >
Reviewed-by: Jeff Cody <jc...@redhat.com> > --- > v2: no change > --- > block/stream.c | 24 ++++++++++-------------- > 1 file changed, 10 insertions(+), 14 deletions(-) > > diff --git a/block/stream.c b/block/stream.c > index 746d525..2f9618b 100644 > --- a/block/stream.c > +++ b/block/stream.c > @@ -108,12 +108,11 @@ static void coroutine_fn stream_run(void *opaque) > BlockBackend *blk = s->common.blk; > BlockDriverState *bs = blk_bs(blk); > BlockDriverState *base = s->base; > - int64_t sector_num = 0; > - int64_t end = -1; > + int64_t offset = 0; > uint64_t delay_ns = 0; > int error = 0; > int ret = 0; > - int n = 0; > + int n = 0; /* sectors */ > void *buf; > > if (!bs->backing) { > @@ -126,7 +125,6 @@ static void coroutine_fn stream_run(void *opaque) > goto out; > } > > - end = s->common.len >> BDRV_SECTOR_BITS; > buf = qemu_blockalign(bs, STREAM_BUFFER_SIZE); > > /* Turn on copy-on-read for the whole block device so that guest read > @@ -138,7 +136,7 @@ static void coroutine_fn stream_run(void *opaque) > bdrv_enable_copy_on_read(bs); > } > > - for (sector_num = 0; sector_num < end; sector_num += n) { > + for ( ; offset < s->common.len; offset += n * BDRV_SECTOR_SIZE) { > bool copy; > > /* Note that even when no rate limit is applied we need to yield > @@ -151,28 +149,26 @@ static void coroutine_fn stream_run(void *opaque) > > copy = false; > > - ret = bdrv_is_allocated(bs, sector_num, > + ret = bdrv_is_allocated(bs, offset / BDRV_SECTOR_SIZE, > STREAM_BUFFER_SIZE / BDRV_SECTOR_SIZE, &n); > if (ret == 1) { > /* Allocated in the top, no need to copy. */ > } else if (ret >= 0) { > /* Copy if allocated in the intermediate images. Limit to the > - * known-unallocated area [sector_num, sector_num+n). */ > + * known-unallocated area [offset, offset+n*BDRV_SECTOR_SIZE). > */ > ret = bdrv_is_allocated_above(backing_bs(bs), base, > - sector_num, n, &n); > + offset / BDRV_SECTOR_SIZE, n, &n); > > /* Finish early if end of backing file has been reached */ > if (ret == 0 && n == 0) { > - n = end - sector_num; > + n = (s->common.len - offset) / BDRV_SECTOR_SIZE; > } > > copy = (ret == 1); > } > - trace_stream_one_iteration(s, sector_num * BDRV_SECTOR_SIZE, > - n * BDRV_SECTOR_SIZE, ret); > + trace_stream_one_iteration(s, offset, n * BDRV_SECTOR_SIZE, ret); > if (copy) { > - ret = stream_populate(blk, sector_num * BDRV_SECTOR_SIZE, > - n * BDRV_SECTOR_SIZE, buf); > + ret = stream_populate(blk, offset, n * BDRV_SECTOR_SIZE, buf); > } > if (ret < 0) { > BlockErrorAction action = > @@ -211,7 +207,7 @@ out: > /* Modify backing chain and close BDSes in main loop */ > data = g_malloc(sizeof(*data)); > data->ret = ret; > - data->reached_end = sector_num == end; > + data->reached_end = offset == s->common.len; > block_job_defer_to_main_loop(&s->common, stream_complete, data); > } > > -- > 2.9.4 >