[RFC PATCH] getting misc stats/attributes via xattr API

[Karel Zak]

On Tue, May 03, 2022 at 02:23:23PM +0200, Miklos Szeredi wrote:
> Examples:
> 
> $ getfattr -etext -n ":" .
> # file: .
> :="mnt:\000mntns:"
> 
> $ getfattr -etext -n ":mnt:" .
> # file: .
> :mnt:="info"
> 
> $ getfattr -etext -n ":mnt:info" .
> # file: .
> :mnt:info="21 1 254:0 / / rw,relatime - ext4 /dev/root rw\012"

Is there a way how to get mountinfo-like entry by mount ID for some
sub-tree? Something like:

 getfattr -etext -n ":mnt:info:21" /

The interface has to be consistent with some notification system (I
see your question about fsnotify/fanotify at linux-fsdevel) and mount
ID seems better than paths due to over-mounts, etc.

> $ getfattr -etext -n ":mntns:" .
> # file: .
> :mntns:="21:\00022:\00024:\00025:\00023:\00026:\00027:\00028:\00029:\00030:\00031:"
> 
> $ getfattr -etext -n ":mntns:28:" .
> # file: .
> :mntns:28:="info"

  Karel

-- 
 Karel Zak  <kzak at redhat.com>
 http://karelzak.blogspot.com