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Re: [Qemu-devel] Qemu-img convert with -B


From: Brad Campbell
Subject: Re: [Qemu-devel] Qemu-img convert with -B
Date: Thu, 28 Apr 2011 17:38:17 +0800
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On 28/04/11 14:36, Kevin Wolf wrote:
Am 28.04.2011 04:06, schrieb Brad Campbell:
On 27/04/11 22:02, Brad Campbell wrote:
On 27/04/11 21:56, Kevin Wolf wrote:

When you don't have a backing file, leaving an cluster unallocated means
that it's zero. When you have a backing file, it could be anything. So
if qemu-img convert wanted to save this space, it would have to read
from the backing file and leave the cluster unallocated if it reads as
zero.

This is something that qemu-img doesn't do today.
This passes cursory testing, but I'm just wondering if this is along the
right lines?
I haven't checked all details, but it looks like what I would have done.
(Though something is wrong with your indentations, I suspect that the
patch wouldn't apply)


Odd, I generated it with git diff. Must have lost something in the copy & paste 
from the terminal.

I'm using tabs=spaces and a ts of 4 in vim. It seemed to fit in with the rest 
of the file.

@@ -939,9 +957,16 @@ out:
       free_option_parameters(create_options);
       free_option_parameters(param);
       qemu_free(buf);
+    if (buf3) {
+        qemu_free(buf3);
+    }
qemu_free (and the libc free, too) work just fine with NULL, so the
check isn't needed.

I ran some more tests on it and there are some small issues I need to fix up, but it does what it says on the tin.

Cheers for the feedback, I'll do some cleanups and prepare something for 
submission.

Regards,
Brad



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