lsfd: add shortcut for --file (or --inode) and --fs

[mjt0k]

lsof has a very useful feature, lsof /file/name to list processes which has this file open. An alternative with lsfd for this is to get the inode number and filesystem id of this file and use lsof -Q 'INODE == 4321 && MNTID == 123. This is just too clumsy for regular usage. This is what I'd suggest to have --inode. Note: it is not really -Q 'NAME == "/file/name"' - since the file might be open by more than single name in case it has multiple links, - this is why --file is different from --inode.

And another very useful shortcut is --fs /mntpt (or --mountpoint /mntpt) - to list all files open from the given filesystem (which should be equivalent to -Q 'MNTID == 123', I think).

[masatake]

I'll work on this item after #2531 is merged.

This one was in the checklists .

[masatake]

Like Wireshark, lsfd has two types of filters.

1. early filter, working in the gathering-data stage, and
2. display filter, working in the printing-result stage

-Q option is for specifying display filters.

--file, --inode, and maybe --fs can be implemented in the early filter.

Before implementing --inode, I must solve the btrfs-specific issue:

#2349 (comment)

[masatake]

#2349 was solved via #2803. I'll try to solve this issue.

[masatake]

@karelzak Could you assign me to this issue?