Re: [PATCH 34/38] vfs: syscall: Add fsinfo() to query filesystem information [ver #10]
From: Al Viro <viro@ZenIV.linux.org.uk>
Date: 2018-07-31 05:55:00
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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...