Re: [PATCH 34/38] vfs: syscall: Add fsinfo() to query filesystem information [ver #10]

Al Viro
2018-07-31T04:16:47Z

On Fri, Jul 27, 2018 at 06:35:10PM +0100, David Howells wrote:
> params->request indicates the attribute/attributes to be queried. This can
> be one of:
>
> fsinfo_attr_statfs - statfs-style info
> fsinfo_attr_fsinfo - Information about fsinfo()
> fsinfo_attr_ids - Filesystem IDs
> fsinfo_attr_limits - Filesystem limits
> fsinfo_attr_supports - What's supported in statx(), IOC flags
> fsinfo_attr_capabilities - Filesystem capabilities
> fsinfo_attr_timestamp_info - Inode timestamp info
> fsinfo_attr_volume_id - Volume ID (string)
> fsinfo_attr_volume_uuid - Volume UUID
> fsinfo_attr_volume_name - Volume name (string)
> fsinfo_attr_cell_name - Cell name (string)
> fsinfo_attr_domain_name - Domain name (string)
> fsinfo_attr_realm_name - Realm name (string)
> fsinfo_attr_server_name - Name of the Nth server (string)
> fsinfo_attr_server_address - Mth address of the Nth server
> fsinfo_attr_parameter - Nth mount parameter (string)
> fsinfo_attr_source - Nth mount source name (string)
> fsinfo_attr_name_encoding - Filename encoding (string)
> fsinfo_attr_name_codepage - Filename codepage (string)
> fsinfo_attr_io_size - I/O size hints

Umm... What's so special about cell/volume/domain/realm? And
what do we do when a random filesystem gets added - should its
parameters go into catch-all pile (attr_parameter), or should they
get classes of their own?

For Cthulhu sake, who's going to maintain that enum in face of
random out-of-tree filesystems, each wanting a class or two its own?
We'd tried that with device numbers; ask hpa how well has that
worked and how much did he love the whole experience...