From 4ebe0617269113ec52a74d3dbb574a62ef6a0c83 Mon Sep 17 00:00:00 2001 From: Sam Eiderman Date: Thu, 23 May 2019 19:33:35 +0300 Subject: [PATCH] qemu-img: rebase: Reuse parent BlockDriverState In safe mode we open the entire chain, including the parent backing file of the rebased file. Do not open a new BlockBackend for the parent backing file, which saves opening the rest of the chain twice, which for long chains saves many "pricy" bdrv_open() calls. Permissions for blk_new() were copied from blk_new_open() when flags = 0. Reviewed-by: Karl Heubaum Reviewed-by: Eyal Moscovici Signed-off-by: Sagi Amit Co-developed-by: Sagi Amit Signed-off-by: Sam Eiderman Message-id: 20190523163337.4497-2-shmuel.eiderman@oracle.com Signed-off-by: Max Reitz --- qemu-img.c | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-) diff --git a/qemu-img.c b/qemu-img.c index 28fba1e7a7..9bd0bb1e47 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3309,29 +3309,18 @@ static int img_rebase(int argc, char **argv) /* For safe rebasing we need to compare old and new backing file */ if (!unsafe) { - char backing_name[PATH_MAX]; QDict *options = NULL; + BlockDriverState *base_bs = backing_bs(bs); - if (bs->backing) { - if (bs->backing_format[0] != '\0') { - options = qdict_new(); - qdict_put_str(options, "driver", bs->backing_format); - } - - if (force_share) { - if (!options) { - options = qdict_new(); - } - qdict_put_bool(options, BDRV_OPT_FORCE_SHARE, true); - } - bdrv_get_backing_filename(bs, backing_name, sizeof(backing_name)); - blk_old_backing = blk_new_open(backing_name, NULL, - options, src_flags, &local_err); - if (!blk_old_backing) { + if (base_bs) { + blk_old_backing = blk_new(BLK_PERM_CONSISTENT_READ, + BLK_PERM_ALL); + ret = blk_insert_bs(blk_old_backing, base_bs, + &local_err); + if (ret < 0) { error_reportf_err(local_err, - "Could not open old backing file '%s': ", - backing_name); - ret = -1; + "Could not reuse old backing file '%s': ", + base_bs->filename); goto out; } } else {