From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [RFC PATCH 0/7] Non-blockling buffered fs read (page cache only) Date: Fri, 19 Sep 2014 04:23:55 -0700 Message-ID: <20140919112355.GB4639@infradead.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Milosz Tanski , linux-kernel@vger.kernel.org, Christoph Hellwig , linux-fsdevel@vger.kernel.org, linux-aio@kvack.org, Mel Gorman , Volker Lendecke , Tejun Heo , michael.kerrisk@gmail.com To: Jeff Moyer Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-aio@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Sep 15, 2014 at 05:58:44PM -0400, Jeff Moyer wrote: > I thought you were going to introduce a new flag instead of using > O_NONBLOCK for this. I dug up an old email that suggested that enabling > O_NONBLOCK for regular files (well, a device node in this case) broke a > cd ripping or burning application. I also found this old bugzilla, > which states that squid would fail to start, and that gqview was also > broken: > https://bugzilla.redhat.com/show_bug.cgi?id=136057 That is why we avoid looking a the per-open O_NONBLOCK flag, and only apply it per I/O. As mentioned in my last mail it's not quite as trivial but still fairly easy to also do that for writes. > I don't think O_NONBLOCK is the right flag. What you're really > specifying is a flag that prevents I/O in the read path, and nowhere > else. As such, I'd feel much better about this if we defined a new flag > (O_NONBLOCK_READ maybe? No, that's too verbose.). > > In summary, I like the idea, but I worry about overloading O_NONBLOCK. There's a fair argument we could use a different namespace for the per-I/O ops, and it seems like Miklos already implemented this for the next version. -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: aart@kvack.org