From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heinrich Schuchardt Subject: Re: [PATCH v2 1/1] ftruncate, truncate: create fanotify events Date: Tue, 11 Nov 2014 20:55:26 +0100 Message-ID: <546269AE.4050200@gmx.de> References: <20141007192330.GE30038@quack.suse.cz> <1414100107-3750-1-git-send-email-xypron.glpk@gmx.de> <20141110203029.GA8125@quack.suse.cz> <20141111073415.GA21776@infradead.org> <20141111110943.GD10456@quack.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: Eric Paris , Alexander Viro , OGAWA Hirofumi , Jeff Layton , "J. Bruce Fields" , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Jan Kara , Christoph Hellwig Return-path: In-Reply-To: <20141111110943.GD10456@quack.suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 11.11.2014 12:09, Jan Kara wrote: > On Mon 10-11-14 23:34:15, Christoph Hellwig wrote: >> On Mon, Nov 10, 2014 at 09:30:29PM +0100, Jan Kara wrote: >>> So what I somewhat dislike about this patch is that notify_change() is >>> sometimes called with dentry and sometimes with path. That way it's not >>> completely clear when fanotify events will be generated and when not. No. With my patch notify_change is still only called with dentry. It is only new function notify_change_path which will be called with a path. And this function will only be called from do_truncate up to now. >>> Sadly it isn't easy to provide struct path in all the places where we are >>> calling notify_change() so I'm not sure what would a better solution look >>> like either :( We only want to create FAN_MODIFY events for ATTR_SIZE. So only for these events we need a path. To my knowledge notify_change is called with ATTR_SIZE from do_truncate(), ecryptfs_truncate() and will be called with ATTR_SIZE from ovl_setattr() for a truncation. ecryptfs_dentry_to_lower_path() could be used in ecryptfs_truncate() to obtain a path. ovl_path_upper() could be used in ovl_setattr() to obtain a path. >> >> I suspect the right thing to do is to split out the truncate path >> from notify_change, as it's fairly different anyway. > Yeah, that would make sense. I wanted to say it's quite a lot of work to > change all the filesystems (where the separation of truncate path makes > sense as well IMHO) but actually it's possible to just do the separation at > the VFS level and still call ->setattr() fs callback for now. Heinrich will > you look into this? You seem to agree that struct path has to passed to do_truncate() and further to the notification layer. Currently do_truncate() calls notify_change() which does not accept a path argument. Here the size change is implemented as an attribute change. Furthermore time attributes are changed. What do you exactly mean by > just do the separation at the virtual file system level > and still call ->setattr() fs callback for now. Do you want to duplicate the logic of notify_change() to a new function notify_truncate() which will at least have to handle ATTR_SIZE, ATTR_FORCE, ATTR_KILL_SUID, ATTR_KILL_SGID, ATTR_FILE and time attributes? And from notify_truncate() call new function fsnotify_truncate() with a logic like fsnotify_modify() but accepting a path? This would result in a lot of code duplication. In which respect would such a patch be preferable? Best regards Heinrich Schuchardt