Re: fatfs write support

[Thomas Bushnell, BSG]

Marco Gerards <metgerards@student.han.nl> writes:

> -  When diskfs_cached_lookup is called, but it is not clear yet if the
>    directory is locked.  Because this is where the node is crated and
>    locked, it should know if it will be locked.  I propose to add the
>    flag that was discussed earlier to diskfs_cached_lookup.

Yes; I think this is necessary regardless.

> - Some RPCs can't be supported when "diskfs_metadata_in_directories"
>   is used.  Those calls should return EOPNOTSUP (right?).  An example
>   of this is "dir_link".

This is a limitation in fatfs; you should not assume that it is a
limitation in every diskfs_metadata_in_directories system.

As it happens, for dir_link in this case the correct error is EMLINK.
And you don't have to do anything special; fatfs should set
diskfs_link_max to 1, and all the right stuff will happen
automatically.  (And, it will have to implement dir_rename itself,
since the diskfs version of that routine can't function if
diskfs_link_max is 1, as the comments in <hurd/diskfs.h> indicate.)

Thomas