From fc0932fdcfc3e5cafa3641e361b681c07f639812 Mon Sep 17 00:00:00 2001 From: Fam Zheng Date: Wed, 3 May 2017 00:35:53 +0800 Subject: [PATCH] block: Reuse bs as backing hd for drive-backup sync=none Opening the backing image for the second time is bad, especially here when it is also in use as the active image as the source. The drive-backup job itself doesn't read from target->backing for COW, instead it gets data from the write notifier, so it's not a big problem. However, exporting the target to NBD etc. won't work, because of the likely stale metadata cache. Use BDRV_O_NO_BACKING in this case and manually set up the backing BdrvChild. Cc: qemu-stable@nongnu.org Signed-off-by: Fam Zheng Signed-off-by: Kevin Wolf --- blockdev.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/blockdev.c b/blockdev.c index 0b38c3df71..0d3773bcb8 100644 --- a/blockdev.c +++ b/blockdev.c @@ -3151,6 +3151,7 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, Error *local_err = NULL; int flags; int64_t size; + bool set_backing_hd = false; if (!backup->has_speed) { backup->speed = 0; @@ -3201,6 +3202,8 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, } if (backup->sync == MIRROR_SYNC_MODE_NONE) { source = bs; + flags |= BDRV_O_NO_BACKING; + set_backing_hd = true; } size = bdrv_getlength(bs); @@ -3227,7 +3230,9 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, } if (backup->format) { - options = qdict_new(); + if (!options) { + options = qdict_new(); + } qdict_put_str(options, "driver", backup->format); } @@ -3238,6 +3243,14 @@ static BlockJob *do_drive_backup(DriveBackup *backup, BlockJobTxn *txn, bdrv_set_aio_context(target_bs, aio_context); + if (set_backing_hd) { + bdrv_set_backing_hd(target_bs, source, &local_err); + if (local_err) { + bdrv_unref(target_bs); + goto out; + } + } + if (backup->has_bitmap) { bmap = bdrv_find_dirty_bitmap(bs, backup->bitmap); if (!bmap) {