We've got a long-standing complaint that tools like lsof, when run on an NFS server, overlook opens and locks held by NFS clients. The information's all there, it's just a question of how to expose it. Easiest might be a single flat file like /proc/locks, but I've always hoped we could do something slightly more structured, using a subdirectory per NFS client. Jeff Layton looked into this several years ago. I don't remember if there was some particular issue or if he just got bogged down in VFS details. My concerns are that: - I'd like the format to be easily expandable. The option to create new files seems like it would help. - some of the data we'd like to expose may be kind of cumbersome include as a column in a text file. (I'm thinking of the NFSv4 client identifier, which the protocol allows to be up to 1K of binary data, even if most (all?) clients use shorter ascii identifiers.) I'm not sure I'd want to go as far as a sysfs-like one-value-per-file rule, which seems like overkill? In a little more detail, as starting point, I was considering naming each client directory with a small integer, and including files like: info: a text file with NFS protocol version ascii representation of client address krb5 principal if available clientid: NFSv4 client ID; file absent for NFSv2/3 clients. locks: list of locks, following something like the /proc/locks format. opens: list of file opens, with access bits, inode numbers, device number. Does that sound reasonable? Any other ideas? --b.
