fsnotify & sysfs

fsnotify & sysfs

[Rodolfo Giometti]

Hello,

I know that a sysfs file may be pollable but I'm asking to myself how
it could be difficult adding notifying support also.

Maybe adding a call to the fsnotify subsystem within the
sysfs_notify() function as follow can do the trick?

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index da3fefe..afee69f 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -484,8 +486,10 @@ void sysfs_notify(struct kobject *k, const char
*dir, const
                sd = sysfs_find_dirent(sd, NULL, dir);
        if (sd && attr)
                sd = sysfs_find_dirent(sd, NULL, attr);
-       if (sd)
+       if (sd) {
                sysfs_notify_dirent(sd);
+               fsnotify_change(dentry, ATTR_SIZE);
+       }
 
        mutex_unlock(&sysfs_mutex);
 }

However my problem is how to get the struct dentry pointer needed by
fsnotify_change() related to the struct sysfs_dirent pointer passed to
sysfs_notify(). :(

Can you please give me any advice about to solve it?

Another question: in file linux/fs/sysfs/file.c I see:

   #include <linux/fsnotify.h>

but none of its functions are called into file.c... maybe it's a
mistake?

Thanks in advance,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail: giometti@enneenne.com
Linux Device Driver                          giometti@linux.it
Embedded Systems                     phone:  +39 349 2432127
UNIX programming                     skype:  rodolfo.giometti
Freelance ICT Italia - Consulente ICT Italia - www.consulenti-ict.it

Re: fsnotify & sysfs

[Greg KH]

On Sun, Dec 12, 2010 at 01:42:47PM +0100, Rodolfo Giometti wrote:
> Hello,
> 
> I know that a sysfs file may be pollable but I'm asking to myself how
> it could be difficult adding notifying support also.
> 
> Maybe adding a call to the fsnotify subsystem within the
> sysfs_notify() function as follow can do the trick?

Perhaps, does that work?

> However my problem is how to get the struct dentry pointer needed by
> fsnotify_change() related to the struct sysfs_dirent pointer passed to
> sysfs_notify(). :(

Yup, that's a problem :(

> Can you please give me any advice about to solve it?
> 
> Another question: in file linux/fs/sysfs/file.c I see:
> 
>    #include <linux/fsnotify.h>
> 
> but none of its functions are called into file.c... maybe it's a
> mistake?

Possibly, but look at the patch that added that line, perhaps it was put
there for a reason.

thanks,

greg k-h