Re: [fuse-devel] mmap not working with fuse 2.6.0rc3

[Miklos S. <mi...@sz...>]

> Hello, I'm developing a filesystem based on the provided fusexmp.c so
> it has the real filesystem as backend.
> I'm making some tests and it seems to work for the most part but one
> test implies installing a debian package through that filesystem. When
> I executed the corresponding apt-get install I got the following
> output:
>=20
> Leyendo lista de paquetes... =C2=A1Error!
> E: No pude hacer mmap de 12582912 bytes - mmap (19 No such device)
> W: Unable to munmap
> E: No se pudieron analizar o abrir las listas de paquetes o el archivo
> de estado.
>=20
> Basically it fails because it cannot make a mmap of 12582912 bytes.
> I have the filesystem mounted with -o allow_other,use_ino but I've
> tried without use_ino too and the result it's the same.
> Is there something I can do? I have read that FUSE does not support
> all kind of mmaps.

That's right.  It could be that apt-get uses a writable shared
mapping, which is not supported by fuse.

The other possibility is that you are setting the 'direct_io' flag in
open, or using the 'direct_io' mount option, in which case mmap is not
supported at all.

Miklos