Subject: Re: [RFC][PATCH] inotify 0.10.0
From: John McCutchan <ttb@tentacle.dhs.org>
To: Mike Waychison <Michael.Waychison@sun.com>
Cc: linux-kernel@vger.kernel.org, gamin-list@gnome.org, rml@ximian.com,
       viro@parcelfarce.linux.theplanet.co.uk, akpm@osdl.org, iggy@gentoo.org
In-Reply-To: <4159A187.3060402@sun.com>
References: <1096250524.18505.2.camel@vertex>  <4159A187.3060402@sun.com>
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Date: Tue, 28 Sep 2004 16:35:40 -0400
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On Tue, 2004-09-28 at 13:38, Mike Waychison wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> John McCutchan wrote:
> |
> | --Why Not dnotify and Why inotify (By Robert Love)--
> |
> 
> | * inotify has an event that says "the filesystem that the item you were
> |   watching is on was unmounted" (this is particularly cool).
> 
> | +++ linux/fs/super.c	2004-09-18 02:24:33.000000000 -0400
> | @@ -36,6 +36,7 @@
> |  #include <linux/writeback.h>		/* for the emergency remount stuff */
> |  #include <linux/idr.h>
> |  #include <asm/uaccess.h>
> | +#include <linux/inotify.h>
> |
> |
> |  void get_filesystem(struct file_system_type *fs);
> | @@ -204,6 +205,7 @@
> |
> |  	if (root) {
> |  		sb->s_root = NULL;
> | +		inotify_super_block_umount (sb);
> |  		shrink_dcache_parent(root);
> |  		shrink_dcache_anon(&sb->s_anon);
> |  		dput(root);
> 
> This doesn't seem right.  generic_shutdown_super is only called when the
> last instance of a super is released.  If a system were to have a
> filesystem mounted in two locations (for instance, by creating a new
> namespace), then the umount and ignore would not get propagated when one
> is unmounted.
> 
> How about an approach that somehow referenced vfsmounts (without having
> a reference count proper)?  That way you could queue messages in
> umount_tree and do_umount..

I was not aware of this subtlety. You are right, we should make sure
events are sent for every unmount, not just the last.

John
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