[CRIU] [PATCH 03/18] fsnotify: Extend protobuf format to keep notification type and specific parameters

[Cyrill Gorcunov]

On Mon, Jan 14, 2013 at 01:12:14PM +0400, Pavel Emelyanov wrote:
> On 01/11/2013 08:58 PM, Cyrill Gorcunov wrote:
> > 
> > fanotify requires additional parameters to be stored so we need
> > to extend protobuf
> > 
> >  - each file entry will have a @type of the notification it hosts
> > 
> >  - additional parameters for fanotify_init call (global flags
> >    and event flags) will be stored in optional @faglob entry
> > 
> >  - the watch descriptor (or mark in terms of kernel) now host
> >    the @type of the notification it represent and mark flags
> >    @mflags needed for fanotify objects (initially I've been
> >    reusing @wd field for that but Pavel pointed that better
> >    to not create mess in a sake of saving couple of bytes
> >    in image)
> > 
> > Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
> > ---
> >  protobuf/fsnotify.proto | 24 ++++++++++++++++++++++++
> >  1 file changed, 24 insertions(+)
> > 
> 
> > +/*
> > + * There are a couple of tricks implied to distinguish if fsnotify
> > + * marks set on inode or mount point: the mount points do not
> > + * have i_ino, ignored_mask, f_handle, the mount points
> > + * have @type set to FANOTIFY. wd for inotify points to real
> > + * file descriptor number.
> > + */
> 
> I don't understand this comment. Please, describe how each field below
> is used for inotify and fanotify wd-s.
> 
> message inotify_wd_entry {
>         required uint32         id              = 1;
>         required uint64         i_ino           = 2;
>         required uint32         mask            = 3;
>         required uint32         ignored_mask    = 4;
>         required uint32         s_dev           = 5;
>         required uint32         wd              = 6;
>         required fh_entry       f_handle        = 7;
> +	optional fsnotify_type	type		= 8;
> +	optional uint32		mflags		= 9;
> }

inotify uses
------------
	id, i_ino, mask, ignored_mask, s_dev, wd, f_handle

fanotify uses
-------------
	on inodes
	---------
	id, i_ino, mask, ignored_mask, f_handle, mflags

	on mount points
	---------------
	id, i_ino = 0, f_handle = 0, mask, ignored_mask, s_dev, mflags

@type is set to either FSNOTIFY_TYPE__INOTIFY or FSNOTIFY_TYPE__FANOTIFY