From 981fb5810aa3f68797ee6e261db338bd78857614 Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Fri, 20 Sep 2019 17:20:42 +0300 Subject: [PATCH] block/backup: fix max_transfer handling for copy_range Of course, QEMU_ALIGN_UP is a typo, it should be QEMU_ALIGN_DOWN, as we are trying to find aligned size which satisfy both source and target. Also, don't ignore too small max_transfer. In this case seems safer to disable copy_range. Fixes: 9ded4a0114968e Signed-off-by: Vladimir Sementsov-Ogievskiy Message-id: 20190920142056.12778-2-vsementsov@virtuozzo.com Signed-off-by: Max Reitz --- block/backup.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/block/backup.c b/block/backup.c index 763f0d7ff6..db20249063 100644 --- a/block/backup.c +++ b/block/backup.c @@ -741,12 +741,19 @@ BlockJob *backup_job_create(const char *job_id, BlockDriverState *bs, job->cluster_size = cluster_size; job->copy_bitmap = copy_bitmap; copy_bitmap = NULL; - job->use_copy_range = !compress; /* compression isn't supported for it */ job->copy_range_size = MIN_NON_ZERO(blk_get_max_transfer(job->common.blk), blk_get_max_transfer(job->target)); - job->copy_range_size = MAX(job->cluster_size, - QEMU_ALIGN_UP(job->copy_range_size, - job->cluster_size)); + job->copy_range_size = QEMU_ALIGN_DOWN(job->copy_range_size, + job->cluster_size); + /* + * Set use_copy_range, consider the following: + * 1. Compression is not supported for copy_range. + * 2. copy_range does not respect max_transfer (it's a TODO), so we factor + * that in here. If max_transfer is smaller than the job->cluster_size, + * we do not use copy_range (in that case it's zero after aligning down + * above). + */ + job->use_copy_range = !compress && job->copy_range_size > 0; /* Required permissions are already taken with target's blk_new() */ block_job_add_bdrv(&job->common, "target", target, 0, BLK_PERM_ALL,