Re: [Qemu-devel] [PATCH v2] qemu-img: let 'qemu-img convert' flush data

[Liu Yuan]

On 04/11/2012 11:01 PM, Paolo Bonzini wrote:

> bdrv_delete already does this.
> 
> Paolo


Ah yes. Thanks pointing out.

>From 459414f677f6449482f9cfcb7917ff0e242ad490 Mon Sep 17 00:00:00 2001
From: Liu Yuan <address@hidden>
Date: Wed, 11 Apr 2012 23:19:54 +0800
Subject: [PATCH v3] qemu-img: let 'qemu-img convert' flush data

The 'qemu-img convert -h' advertise that the default cache mode is
'writeback', while in fact it is 'unsafe'.

This patch 1) fix the help manual and 2) let bdrv_close() call bdrv_flush()

2) is needed because some backend storage doesn't have a self-flush
mechanism(for e.g., sheepdog), so we need to call bdrv_flush() to make
sure the image is really writen to the storage instead of hanging around
writeback cache forever.

Signed-off-by: Liu Yuan <address@hidden>
---
 block.c    |    1 +
 qemu-img.c |    4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/block.c b/block.c
index c0c90f0..1ee2bf0 100644
--- a/block.c
+++ b/block.c
@@ -812,6 +812,7 @@ unlink_and_fail:

 void bdrv_close(BlockDriverState *bs)
 {
+    bdrv_flush(bs);
     if (bs->drv) {
         if (bs->job) {
             block_job_cancel_sync(bs->job);
diff --git a/qemu-img.c b/qemu-img.c
index 6a61ca8..6e54db3 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -66,8 +66,8 @@ static void help(void)
            "  'filename' is a disk image filename\n"
            "  'fmt' is the disk image format. It is guessed
automatically in most cases\n"
            "  'cache' is the cache mode used to write the output disk
image, the valid\n"
-           "    options are: 'none', 'writeback' (default),
'writethrough', 'directsync'\n"
-           "    and 'unsafe'\n"
+           "    options are: 'none', 'writeback', 'writethrough',
'directsync'\n"
+           "    and 'unsafe' (default)\n"
            "  'size' is the disk image size in bytes. Optional suffixes\n"
            "    'k' or 'K' (kilobyte, 1024), 'M' (megabyte, 1024k), 'G'
(gigabyte, 1024M)\n"
            "    and T (terabyte, 1024G) are supported. 'b' is ignored.\n"
-- 
1.7.8.2