Re: [Qemu-block] block/nfs: Fine grained runtime options in nfs

[Ashijeet Acharya]

On Fri, Oct 14, 2016 at 9:16 PM, Stefan Hajnoczi  wrote:
> On Mon, Oct 10, 2016 at 10:39:30AM +0530, Ashijeet Acharya wrote:
>> Hi all,
>>
>> I was working on trying to add blockdev-add compatibility for the nfs
>> block driver but before that runtime options need to be separated into
>> various options rather than just a simple "filename" option.
>>
>> I have added the following until now:
>> a) host
>> b) port (not sure about this one, do we just use a default port number?)
>> c) export
>> d) path (path to the file)
>>
>> I have matched these with the URI but still let me know if i have
>> missed anyone :)
>>
>> Now, in order to parse the uri for different runtime options, I have
>> made two new functions nfs_parse_filename() and nfs_parse_uri() which
>> is pretty similar to the way how other network block drivers do it.
>>
>> Currently we parse the uri in a nfs_client_open() function which takes
>> 'const char *filename' as one of its parameters but I dont think
>> that's the right way anymore because we pass 'qemu_opt_get(opts,
>> "filename")' which is invalid due to no runtime option named
>> "filename" available anymore. Right?
>>
>> While parsing uri we check for the query parameters inside a 'for
>> loop', so I have moved that too inside
>>
>> nfs_parse_uri(const char *filename, QDict *options, Error **errp)
>>
>> but the problem is there is no struct NFSClient parameter here, so I
>> cannot fill up its important fields while parsing the query
>> parameters. I cannot do the same inside nfs_client_open() because I no
>> longer parse the uri over there.OR CAN I? A completely different
>> approach will work too :)
>>
>> I can attach a pastebin link containing a raw patch if you want to get
>> a clear view but I am afraid it doesn't compile at the moment due to
>> the problems mentioned above.
>
> Please post the code and annotate the relevant places where you are
> stuck.

I have solved the issues I was facing earlier (thanks to Max!).
One more relatively easy question though, will we include @port as an
option in runtime_opts while converting NFS to use several
runtime_opts? The reason I ask this because the uri syntax for NFS in
QEMU looks like this:

   nfs:[?param=value[=value2[&...]]]

At the moment my runtime_opts looks like this:

static QemuOptsList runtime_opts = {
.name = "nfs",
.head = QTAILQ_HEAD_INITIALIZER(runtime_opts.head),
.desc = {
{
.name = "host",
.type = QEMU_OPT_STRING,
.help = "Host to connect to",
},
{
.name = "export",
.type = QEMU_OPT_STRING,
.help = "Name of the NFS export to open",
},
{
.name = "path",
.type = QEMU_OPT_STRING,
.help = "Path of the image on the host",
},
{
.name = "uid",
.type = QEMU_OPT_NUMBER,
.help = "UID value to use when talking to the server",
},
{
.name = "gid",
.type = QEMU_OPT_NUMBER,
.help = "GID value to use when talking to the server",
},
{
.name = "tcp-syncnt",
.type = QEMU_OPT_NUMBER,
.help = "Number of SYNs to send during the session establish",
},
{
.name = "readahead",
.type = QEMU_OPT_NUMBER,
.help = "Set the readahead size in bytes",
},
{
.name = "pagecache",
.type = QEMU_OPT_NUMBER,
.help = "Set the pagecache size in bytes",
},
{
.name = "debug",
.type = QEMU_OPT_NUMBER,
.help = "Set the NFS debug level (max 2)",
},
{ /* end of list */ }
},
};

Any comment on including several query params of the uri in
runtime_opts will be helpful too.

Ashijeet

> Stefan

Re: [Qemu-block] block/nfs: Fine grained runtime options in nfs

[Stefan Hajnoczi]

On Mon, Oct 10, 2016 at 10:39:30AM +0530, Ashijeet Acharya wrote:
> Hi all,
> 
> I was working on trying to add blockdev-add compatibility for the nfs
> block driver but before that runtime options need to be separated into
> various options rather than just a simple "filename" option.
> 
> I have added the following until now:
> a) host
> b) port (not sure about this one, do we just use a default port number?)
> c) export
> d) path (path to the file)
> 
> I have matched these with the URI but still let me know if i have
> missed anyone :)
> 
> Now, in order to parse the uri for different runtime options, I have
> made two new functions nfs_parse_filename() and nfs_parse_uri() which
> is pretty similar to the way how other network block drivers do it.
> 
> Currently we parse the uri in a nfs_client_open() function which takes
> 'const char *filename' as one of its parameters but I dont think
> that's the right way anymore because we pass 'qemu_opt_get(opts,
> "filename")' which is invalid due to no runtime option named
> "filename" available anymore. Right?
> 
> While parsing uri we check for the query parameters inside a 'for
> loop', so I have moved that too inside
> 
> nfs_parse_uri(const char *filename, QDict *options, Error **errp)
> 
> but the problem is there is no struct NFSClient parameter here, so I
> cannot fill up its important fields while parsing the query
> parameters. I cannot do the same inside nfs_client_open() because I no
> longer parse the uri over there.OR CAN I? A completely different
> approach will work too :)
> 
> I can attach a pastebin link containing a raw patch if you want to get
> a clear view but I am afraid it doesn't compile at the moment due to
> the problems mentioned above.

Please post the code and annotate the relevant places where you are
stuck.

Stefan


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[Qemu-block] block/nfs: Fine grained runtime options in nfs

[Ashijeet Acharya]

Hi all,

I was working on trying to add blockdev-add compatibility for the nfs
block driver but before that runtime options need to be separated into
various options rather than just a simple "filename" option.

I have added the following until now:
a) host
b) port (not sure about this one, do we just use a default port number?)
c) export
d) path (path to the file)

I have matched these with the URI but still let me know if i have
missed anyone :)

Now, in order to parse the uri for different runtime options, I have
made two new functions nfs_parse_filename() and nfs_parse_uri() which
is pretty similar to the way how other network block drivers do it.

Currently we parse the uri in a nfs_client_open() function which takes
'const char *filename' as one of its parameters but I dont think
that's the right way anymore because we pass 'qemu_opt_get(opts,
"filename")' which is invalid due to no runtime option named
"filename" available anymore. Right?

While parsing uri we check for the query parameters inside a 'for
loop', so I have moved that too inside

nfs_parse_uri(const char *filename, QDict *options, Error **errp)

but the problem is there is no struct NFSClient parameter here, so I
cannot fill up its important fields while parsing the query
parameters. I cannot do the same inside nfs_client_open() because I no
longer parse the uri over there.OR CAN I? A completely different
approach will work too :)

I can attach a pastebin link containing a raw patch if you want to get
a clear view but I am afraid it doesn't compile at the moment due to
the problems mentioned above.

Any help will be appreciated.

Thanks for reading
Ashijeet