From ce8b8f9fe79b09fe6c1d207274b60fcb6a6e08a9 Mon Sep 17 00:00:00 2001 From: Andrey Drobyshev Date: Tue, 19 Sep 2023 19:57:59 +0300 Subject: qemu-img: rebase: use backing files' BlockBackend for buffer alignment Since commit bb1c05973cf ("qemu-img: Use qemu_blockalign"), buffers for the data read from the old and new backing files are aligned using BlockDriverState (or BlockBackend later on) referring to the target image. However, this isn't quite right, because buf_new is only being used for reading from the new backing, while buf_old is being used for both reading from the old backing and writing to the target. Let's take that into account and use more appropriate values as alignments. Signed-off-by: Andrey Drobyshev Message-ID: <20230919165804.439110-4-andrey.drobyshev@virtuozzo.com> Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- qemu-img.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'qemu-img.c') diff --git a/qemu-img.c b/qemu-img.c index 2b2a3a86ca..e61d996e0f 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3759,8 +3759,13 @@ static int img_rebase(int argc, char **argv) int64_t n; float local_progress = 0; - buf_old = blk_blockalign(blk, IO_BUF_SIZE); - buf_new = blk_blockalign(blk, IO_BUF_SIZE); + if (blk_old_backing && bdrv_opt_mem_align(blk_bs(blk_old_backing)) > + bdrv_opt_mem_align(blk_bs(blk))) { + buf_old = blk_blockalign(blk_old_backing, IO_BUF_SIZE); + } else { + buf_old = blk_blockalign(blk, IO_BUF_SIZE); + } + buf_new = blk_blockalign(blk_new_backing, IO_BUF_SIZE); size = blk_getlength(blk); if (size < 0) { -- cgit v1.2.3