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Re: [fuse-devel] [PATCH 01/25] VFS: move attr_kill logic from notify_cha

To: jlayton@xxxxxxxxxx
Subject: Re: [fuse-devel] [PATCH 01/25] VFS: move attr_kill logic from notify_change into helper function
From: Miklos Szeredi <miklos@xxxxxxxxxx>
Date: Mon, 06 Aug 2007 19:43:46 +0200
Cc: linux-kernel@xxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, codalist@xxxxxxxxxxxxxxxxxxxxxxxx, cluster-devel@xxxxxxxxxx, jfs-discussion@xxxxxxxxxxxxxxxxxxxxx, mikulas@xxxxxxxxxxxxxxxxxxxxxxxx, zippel@xxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, joel.becker@xxxxxxxxxx, wli@xxxxxxxxxxxxxx, reiserfs-devel@xxxxxxxxxxxxxxx, dhowells@xxxxxxxxxx, fuse-devel@xxxxxxxxxxxxxxxxxxxxx, jffs-dev@xxxxxxxx, user-mode-linux-user@xxxxxxxxxxxxxxxxxxxxx, v9fs-developer@xxxxxxxxxxxxxxxxxxxxx, linux-ext4@xxxxxxxxxxxxxxx, linux-cifs-client@xxxxxxxxxxxxxxx, ocfs2-devel@xxxxxxxxxxxxxx, bfennema@xxxxxxxxxxxxxxxxxxxxxx
In-reply-to: <200708061354.l76Ds6sq002260@xxxxxxxxxxxxxxxxxxxx> (message from Jeff Layton on Mon, 6 Aug 2007 09:54:06 -0400)
References: <200708061354.l76Ds6sq002260@xxxxxxxxxxxxxxxxxxxx>
Sender: xfs-bounce@xxxxxxxxxxx
> Separate the handling of the local ia_valid bitmask from the one in
> attr->ia_valid. This allows us to hand off the actual handling of the
> ATTR_KILL_* flags to the .setattr i_op when one is defined.
> 
> notify_change still needs to process those flags for the local ia_valid
> variable, since it uses that to decide whether to return early, and to pass
> a (hopefully) appropriate bitmask to fsnotify_change.

I agree with this change and fuse will make use of it as well.

Maybe instead of unconditionally moving attr_kill_to_mode() inside
->setattr() it could be made conditional based on an inode flag
similarly to S_NOCMTIME.  Advantages:

 - no need to modify a lot of in-tree filesystems
 - no silent breakage of out-of-tree fs

Actually I think the new flag would be used by exacly the same
filesystems as S_NOCMTIME, so maybe it would make sense to rename
S_NOCMTIME to something more generic (S_NOATTRUPDATE or whatever) and
use that.

But that could still break out-of-tree fs, so a separate flag is
probably better.

Miklos


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