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Message-ID: <20140916211211.GG1205@quack.suse.cz> Date: Tue, 16 Sep 2014 23:12:11 +0200 From: Jan Kara <jack@...e.cz> To: Heinrich Schuchardt <xypron.debian@....de> Cc: Andrew Vagin <avagin@...allels.com>, Jan Kara <jack@...e.cz>, Al Viro <viro@...IV.linux.org.uk>, Andrey Vagin <avagin@...nvz.org>, linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, John McCutchan <john@...nmccutchan.com>, Robert Love <rlove@...ve.org>, Eric Paris <eparis@...isplace.org>, Cyrill Gorcunov <gorcunov@...nvz.org>, Pavel Emelyanov <xemul@...allels.com>, "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com> Subject: Re: [PATCH] fs: don't remove inotify watchers from alive inode-s On Sat 13-09-14 18:15:09, Heinrich Schuchardt wrote: > On Tue 09-09-14 02:27:12, Al Viro wrote: > http://lkml.org/lkml/2014/9/8/762 > > I agree that it changes user-visible ABI and I agree the behavior > > isn't really specified in the manpage. > > Shouldn't we start with putting the expected behavior into the > manpage before patching the code? I am missing a patch for > man7/inotify.7. Good idea. Thanks for bringing this up. And ideally we should write it down before settling for a solution to this problem. Because when thinking about it again, some details of the behavior are still vague. > On Mon, Sep 08, 2014 at 04:01:56PM +0400, Andrey Vagin wrote: > http://lkml.org/lkml/2014/9/8/219 > > > > fd = inotify_init1(IN_NONBLOCK); > > deleted = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0666); > > link(path, path_link); > > > > wd_deleted = inotify_add_watch(fd, path_link, IN_ALL_EVENTS); > > > > unlink(path); > > unlink(path_link); > > > > printf(" --- unlink\n"); > > read_evetns(fd); > > > > close(deleted); > > printf(" --- close\n"); > > read_evetns(fd); > > > > Without this patch: > > --- unlink > > 4 (IN_ATTRIB) > > 400 (IN_DELETE_SELF) > > 8000 (IN_IGNORED) > > --- close > > FAIL > > > > With this patch: > > --- unlink > > 4 (IN_ATTRIB) > > 400 (IN_DELETE_SELF) > > --- close > > 8 (IN_CLOSE_WRITE) > > 400 (IN_DELETE_SELF) > > 8000 (IN_IGNORED) > > PASS > > Shouldn't the second IN_DELETE_SELF occur before > --- close ? > Why is IN_CLOSE_WRITE created? So I would like events to be generated until the watched inode really gets deleted. This way simple (non-hardlinked) file behaves and that's what seems "natural". In this light generating IN_CLOSE_WRITE is what we want to do. Generation of IN_DELETE_SELF is less obvious I think. Do we want to generate IN_DELETE_SELF for each hardlink to the inode that gets removed? I don't think so (this actually would be too visible user API change IMHO). To match the single link case I think we want to generate IN_DELETE_SELF when the last link to the file is removed. But then generating it twice like we would do with the above patch is wrong... Opinions? Honza -- Jan Kara <jack@...e.cz> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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