bug#19072: cp does not work with davfs2 (fuse) under GNU/Linux; coreutils-8.21

[Pádraig Brady]

On 16/11/14 10:22, Klaus-Jürgen Wolf wrote:
> With my cloud space provider, I have observed that copying to a davfs2
> mounted cloud space does only work if using tar, e.g.
> 
> tar -cf - sourcefile |tar -xf - -C clouddir
> 
> Doing the same (copying) with cp or mv results in the error messages:
> 
> cp: error writing ‘/home/kj/MyDrive/sourcefile’: Input/output error
> cp: failed to extend ‘/home/kj/MyDrive/sourcefile’: Input/output error
> 
> I suppose cp and mv use a file creation method not appropriate for this
> kind of device. Either coreutils should detect the device and use a method
> better suited, or coreutils should restrain to be plain and simple and make
> use of a simple method working everywhere. (IMHO)

You seem to be getting an EIO error from ftruncate().
That's used when creating sparse files which is automatically enabled
when the source file is sparse.

Does passing --sparse=never avoid the issue for you?

BTW it's surprising that EIO is returned by davfs2 rather than ENOSYS or 
ENOTSUP.
Conceivably if davfs2 did return one of those error codes, then cp could fall 
back
to writing zeros in this unusual case (though it doesn't do that now).

For confirmation of the issue, could you provide the output of this command:

  for i in truncate seek; do
    dd conv=notrunc count=0 seek=1 of=/home/kj/MyDrive/coreutils.test
  done

thanks,
Pádraig.