Weirdness when writing to pseudofs file

[Johannes Lundberg]

On 5/22/19 10:51 AM, Konstantin Belousov wrote:
> On Wed, May 22, 2019 at 10:36:34AM -0700, Johannes Lundberg wrote:
>> Hi
>>
>> I'm fiddling with lindebugfs, which is based on pseudofs. When writing
>> to a file,
>>
>> this works: # echo  1 >> /path/to/file
>>
>> but this does not: # echo 1 > /path/to/file
>>
>> "Operation not supported." is returned before the pseudofs code is even
>> entered.
>>
>> Is this expected behavior? (if so, why?)
> Does the file exist ?
>
> Pseudofs does not implement VOP_CREATE(), which is reasonable.

Yes, it exists and my custom write function is receiving the call for
">>". (which is for example used by drm driver debugfs to do certain
things on demand by accepting write to a debugfs file)