From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: aio openat Re: [PATCH 07/13] aio: enabled thread based async fsync Date: Sat, 19 Mar 2016 19:03:25 -0700 Message-ID: References: <20160120195957.GV6033@dastard> <20160120204449.GC12249@kvack.org> <20160120214546.GX6033@dastard> <20160123043922.GF6033@dastard> <20160314171737.GK17923@kvack.org> <20160320012610.GX17997@ZenIV.linux.org.uk> <20160320015511.GZ17997@ZenIV.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <20160320015511.GZ17997@ZenIV.linux.org.uk> Sender: owner-linux-aio@kvack.org To: Al Viro Cc: Benjamin LaHaise , Dave Chinner , Andrew Morton , linux-fsdevel , Linux API , Linux Kernel Mailing List , linux-aio@kvack.org, linux-mm List-Id: linux-api@vger.kernel.org On Sat, Mar 19, 2016 at 6:55 PM, Al Viro wrote: > > What would make unlazy_walk() fail? And if it succeeds, you are not > in RCU mode anymore *without* restarting from scratch... I don't see your point. You don't want to be in RCU mode any more. You want to either succeed or fail with ECHILD/ESTALE. Then, in the failure case, you go to the thread. What I meant by restarting was the restart that do_filp_open() does, and there it just restarts with "op->lookup_flags", which has RCU_LOOKUP still set, so it would just try to do the RCU lookup again. But I actually notice now that Ben actually disabled that restart if LOOKUP_RCU was set, so that ends up not even happening. Anyway, I'm not saying it's polished and pretty. I think the changes to do_filp_open() are a bit silly, and the code should just use path_openat() directly. Possibly using a new helper (ie perhaps just introduce a "rcu_filp_openat()" thing). But from a design perspective, I think this all looks fine. Linus -- 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