Re: [fuse-devel] unknown mount options

[Yue Li <yl...@pa...>]

hi Nikolaus,


On 2/4/17 8:34 PM, Nikolaus Rath wrote:
> On Feb 04 2017, Yue Li <yli-wUU9E3n5/m56...@pu...> wrote:
>> On 2/4/17 3:17 PM, Nikolaus Rath wrote:
>>> On Feb 02 2017, Yue Li <yli-wUU9E3n5/m56...@pu...> wrote:
>>>> I'm currently using the fuse compiled from the repository, and I'm
>>>> trying the options suggested in the release note:
>>>>
>>>> https://github.com/libfuse/libfuse/releases
>>>>
>>>> Here's command for mounting
>>>>
>>>>     sudo ./run  -omodules=subdir,subdir=/mnt/store ./mount -o allow_other
>>>> -o clone_fd -o writeback_cache
>>>>
>>>> And it gave the error
>>>>
>>>> fuse: unknown option(s): `-o writeback_cache'
>>>>
>>>> Similarly, the max_write option, async_dio and a few others also could
>>>> not be recognized. I'm using the passthrough.c example for the tests above.
>>>>
>>>> Is there any special function I need to call to use these options?
>>>> Thanks!
>>> These are (in general) not options that you can pass on the command line
>>> to the filesystem, but options that the filesystem can internally pass
>>> to libfuse.
>>>
>> Is there any example on passing these options? Or could you point to the
>> corresponding functions for doing this?
> That depends on the option. The recommended way to enable the writeback
> cache is to set a flag in your file system's init() handler, see
> eg. https://github.com/libfuse/libfuse/blob/master/test/test_write_cache.c#L46.
>
>
> Is the documentation at
> http://libfuse.github.io/doxygen/fuse__common_8h.html and
> http://libfuse.github.io/doxygen/fuse__lowlevel_8h.html not clear?

I'm following the documentations and example above to enable 
writeback_cache.

Currently I'm using the high level interfaces, and I did the following 
in the init function to enable writeback_cache and async_dio:

static void *myfs_init(struct fuse_conn_info *conn, struct fuse_config *cfg)
{
   (void) conn;
   cfg->use_ino = 1;
   conn -> want |= FUSE_CAP_WRITEBACK_CACHE;
   conn -> want |= FUSE_CAP_ASYNC_DIO;
   return NULL;
}

Is the above sufficient to turn on the options when using the high-level 
APIs?

Then I'm trying to see how can I set the sizes for write() and read(). 
In the your test code above, it seems you used fuse_opt_parse function 
to set the size for write()? Is there any other way to set this 
variable? Can I change member variables of conn to do so?

And how do we change the size of read() under async_dio?

Thanks for the help!

Best,

Yue