From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [take2] Inotify: nested attributes support. Date: Wed, 26 Nov 2008 00:38:25 -0800 Message-ID: <20081126003825.2b9a92be.akpm@linux-foundation.org> References: <20081125194234.GA24449@ioremap.net> <20081125162434.4feacbbf.akpm@linux-foundation.org> <20081126074239.GA17525@ioremap.net> <20081126001538.4b1c7c99.akpm@linux-foundation.org> <20081126082936.GB17525@ioremap.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20081126082936.GB17525-i6C2adt8DTjR7s880joybQ@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Evgeniy Polyakov Cc: john-jueV0HHMeujJJrXXpGQQMAC/G2K4zDHf@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org, rlove-L7G0xEPcOZbYtjvyW6yDsg@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, pavel-AlSwsSmVLrQ@public.gmane.org, davidn-KzQzY1MbaKjAHznzqCTclw@public.gmane.org, Eric Paris List-Id: linux-api@vger.kernel.org On Wed, 26 Nov 2008 11:29:36 +0300 Evgeniy Polyakov wrote: > On Wed, Nov 26, 2008 at 12:15:38AM -0800, Andrew Morton (akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org) wrote: > > OK, so we have a super-duper framework which will allow us to add pids > > (and other things) to inotify messages. > > Yup :) > > > This still doesn't provide a reason for anyone to be interested in the > > code! Why do we want pids in inotify messages? > > I actually cared only about myself :) > I started the thread and implementation, because my application has to > differentiate IO made by itself and any IO made by system (another > users, crons, whatever else), inotify did not give me that info, so I > extended it. As of others: PID/TID may be used by watching applications > to reduce own load to not process own IO, things like beagle may show > who actually made changes into the file. hrm. Well this is the sort of information which reviewers want to know all about before looking at an implementation. > > And how does this work give that pids are (no longer) system-wide unique? > > It gets pids from the caller's task_struct (via current), so its data is > as unique as process calling getpid() or syscall(__NR_gettid). That means that the code delivers non-unique process identifiers to userspace. A client gets pid=42 but there are seven processes on the machine with that pid. Problem. -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html