[libvirt] [PATCH] qemu: Added support L2 table cache for qcow2 disk.

[Peter Krempa]

On Tue, Jul 03, 2018 at 20:41:54 +0800, dujiancheng wrote:
> From: Dujiancheng <dujiancheng10 at gmail.com>
> 
> dujiancheng (1):
>   qemu: Added support L2 table cache for qcow2 disk.           
>         L2 table cache can be set by the new element diskCache.           
>         Use the following methods to set the L2 table cache           
>         and cache clean interval:           
>         <diskCache>             
>           <cache level='2'> 
>             <size unit='KiB'>10240</size>             
>           </cache>     
>           <clean interval='900'/>           
>         </diskCache>           


Since you insist on sending your own version rather than reusing the
better previously posted version, here are a few things this
patch is missing:

- capability which allows to check whether qemu supports the new
  features
- cache is a property of the image and not the disk, also it needs to be
  configurable for <backingStore> so that it's usable for the upcoming
  blockdev work
- the documentation does not explain how it's supposed to be used.
- the RNG schema indentation is wrong
- the formatter for the XML should not have any logic .. e.g.
  determining that only L2 cache is printed
- the code itself is rather strange and does not allow multiple cache
  levels although the data structure suggests so
- the name for the tests are wrong since this is not disk cache but
  image cache
- there are no checks whether a format supporting the l2 cache is used
  (qcow2 only)
- make syntax-check fails:

--- tests/qemuxml2argvdata/disk-cache.args	2018-07-03 15:29:18.386122485 +0200
+++ -	2018-07-03 15:30:36.263098059 +0200
@@ -22,7 +22,8 @@
 -no-acpi \
 -boot c \
 -usb \
--drive file=/tmp/data.img,format=raw,l2-cache-size=10240,cache-clean-interval=900,if=none,id=drive-virtio-disk0 \
+-drive file=/tmp/data.img,format=raw,l2-cache-size=10240,\
+cache-clean-interval=900,if=none,id=drive-virtio-disk0 \
 -device virtio-blk-pci,bus=pci.0,addr=0x3,drive=drive-virtio-disk0,\
 id=virtio-disk0 \
 -drive file=/tmp/logs.img,format=raw,if=none,id=drive-virtio-disk1 \
Incorrect line wrapping in tests/qemuxml2argvdata/disk-cache.args
Use test-wrap-argv.pl to wrap test data files

> Signed-off-by: dujiancheng <dujiancheng10 at gmail.com>

I think it was pointed out that we prefer real names...

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