From b8816a43865822883ffc9b506e6243c7d986561a Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Fri, 4 Mar 2016 14:52:32 +0100 Subject: [PATCH] block: Make backing files always writeback First of all, we're generally not writing to backing files, but when we do, it's in the context of block jobs which know very well when to flush the image. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- block.c | 5 +++-- tests/qemu-iotests/142.out | 10 +++++----- 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/block.c b/block.c index c4dca31fb2..d050c4bb58 100644 --- a/block.c +++ b/block.c @@ -738,8 +738,9 @@ static void bdrv_backing_options(int *child_flags, QDict *child_options, { int flags = parent_flags; - /* The cache mode is inherited unmodified for backing files */ - qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_WB); + /* The cache mode is inherited unmodified for backing files; except WCE, + * which is only applied on the top level (BlockBackend) */ + qdict_set_default_str(child_options, BDRV_OPT_CACHE_WB, "on"); qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_DIRECT); qdict_copy_default(child_options, parent_options, BDRV_OPT_CACHE_NO_FLUSH); diff --git a/tests/qemu-iotests/142.out b/tests/qemu-iotests/142.out index b555d5a255..abe94c3320 100644 --- a/tests/qemu-iotests/142.out +++ b/tests/qemu-iotests/142.out @@ -62,7 +62,7 @@ cache.direct=on on backing-file cache.writeback=off on none0 Cache mode: writethrough Cache mode: writeback - Cache mode: writethrough + Cache mode: writeback Cache mode: writeback cache.writeback=off on file @@ -143,7 +143,7 @@ cache.writeback=off on none0 Cache mode: writethrough Cache mode: writethrough Cache mode: writeback - Cache mode: writethrough + Cache mode: writeback Cache mode: writeback cache.writeback=off on file @@ -302,7 +302,7 @@ cache.direct=on on backing-file cache.writeback=off on none0 Cache mode: writethrough, direct Cache mode: writeback, direct - Cache mode: writethrough, direct + Cache mode: writeback, direct Cache mode: writeback, direct cache.writeback=off on file @@ -383,7 +383,7 @@ cache.writeback=off on none0 Cache mode: writeback, direct Cache mode: writethrough Cache mode: writeback - Cache mode: writethrough + Cache mode: writeback Cache mode: writeback cache.writeback=off on file @@ -718,7 +718,7 @@ cache.direct=on on backing-file cache.writeback=off on none0 Cache mode: writethrough Cache mode: writeback - Cache mode: writethrough, direct + Cache mode: writeback, direct Cache mode: writeback, direct cache.writeback=off on file