From ba2ab2f2ca4150a7e314fbb19fa158bd8ddc36eb Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Thu, 24 Oct 2013 20:35:06 +0200 Subject: [PATCH] qcow2: Flush image after creation Opening the qcow2 image with BDRV_O_NO_FLUSH prevents any flushes during the image creation. This means that the image has not yet been flushed to disk when qemu-img create exits. This flush is delayed until the next operation on the image involving opening it without BDRV_O_NO_FLUSH and closing (or directly flushing) it. For large images and/or images with a small cluster size and preallocated metadata, this flush may take a significant amount of time and may occur unexpectedly. Reopening the image without BDRV_O_NO_FLUSH right before the end of qcow2_create2() results in hoisting the potentially costly flush into the image creation, which is expected to take some time (whereas successive image operations may be not). Signed-off-by: Max Reitz Reviewed-by: Eric Blake Reviewed-by: Benoit Canet Signed-off-by: Kevin Wolf --- block/qcow2.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/block/qcow2.c b/block/qcow2.c index 01269f9264..6e5d98dc48 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1584,6 +1584,16 @@ static int qcow2_create2(const char *filename, int64_t total_size, } } + bdrv_close(bs); + + /* Reopen the image without BDRV_O_NO_FLUSH to flush it before returning */ + ret = bdrv_open(bs, filename, NULL, + BDRV_O_RDWR | BDRV_O_CACHE_WB, drv, &local_err); + if (error_is_set(&local_err)) { + error_propagate(errp, local_err); + goto out; + } + ret = 0; out: bdrv_unref(bs); -- GitLab