Re: [Qemu-devel] [PATCHv7 0/5] block: add native support for NFS

[Peter Lieven <pl@kamp.de>]

On 29.01.2014 15:22, Peter Lieven wrote:
> On 29.01.2014 14:59, Stefan Hajnoczi wrote:
>> On Wed, Jan 29, 2014 at 09:50:20AM +0100, Peter Lieven wrote:
>>> This adds v6 of the NFS protocol driver + qemu-iotest adjustments.
>>>
>>> v6->v7:
>>>   - removed unsused and partially non-existing libnfs header file includes [Stefan]
>>>   - adjusted usage of qemu_opts_create_nofail [Stefan]
>>>   - removed patch to fix output of qemu-iotest 067
>>>   - only blacklist qemu-iotest 020 for NFS do not change proto from generic to file [Fam]
>> It compiles now but I can't create an image on my /home NFS export:
>>
>> $ ./qemu-img create -f qcow2 'nfs://127.0.0.1/home/stefanha/qemu/test-nfs.img?uid=1000&gid=1000' 8G
>> Formatting 'nfs://127.0.0.1/home/stefanha/qemu/test-nfs.img?uid=1000&gid=1000', fmt=qcow2 size=8589934592 encryption=off cluster_size=65536 lazy_refcounts=off
>> qemu-img: nfs://127.0.0.1/home/stefanha/qemu/test-nfs.img?uid=1000&gid=1000: Failed to create file: nfs_creat_async failed
>>
>> I added printfs to the code, block/nfs.c is mounting /home/stefanha/qemu
>> and tries to create the file /test-nfs.img.
>>
>> I'm using the Linux kernel NFS server.  Unfortunately I don't have more
>> time to debug this but I'd like to test this feature successfully before
>> merging it into QEMU.  Any ideas why libnfs refuses to create the file?
>> (It's failing in nfs_lookuppath_async() with "Path is empty".)
>>
>> Ronnie: libnfs clobbers the nfs->rpc error string so you cannot see the
>> detailed error message:
>>
>> In this case nfs_creat() clobbers the error with "Failed to create file:
>> nfs_creat_async failed".  In fact the message was "Out of memory: failed
>> to start parsing the path components" from nfs_creat_async(), but that's
>> clobbering the true error too.  It really should be "Path is empty" from
>> nfs_lookuppath_async().
> It seems the version in Ronnies repository got broken somewhere after
> my commit d43a8953f5. Can you try with:
>
> https://github.com/plieven/libnfs
Ronnie, commit fb6f3152 "Add support for chdir and getcwd" is bad.

Peter