Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754036AbaJCSTZ (ORCPT ); Fri, 3 Oct 2014 14:19:25 -0400 Received: from kanga.kvack.org ([205.233.56.17]:44768 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751404AbaJCSTX (ORCPT ); Fri, 3 Oct 2014 14:19:23 -0400 Date: Fri, 3 Oct 2014 14:19:22 -0400 From: Benjamin LaHaise To: Kent Overstreet Cc: linux-kernel@vger.kernel.org, Zach Brown , Jeff Moyer , Jens Axboe , Slava Pestov Subject: Re: [PATCH] aio: Fix return code of io_submit() (RFC) Message-ID: <20141003181922.GZ17057@kvack.org> References: <1412359693-2535-1-git-send-email-kmo@daterainc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1412359693-2535-1-git-send-email-kmo@daterainc.com> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Kent, On Fri, Oct 03, 2014 at 11:08:13AM -0700, Kent Overstreet wrote: > io_submit() could return -EAGAIN on memory allocation failure when it should > really have been returning -ENOMEM. This could confuse applications (i.e. fio) > since -EAGAIN means "too many requests outstanding, wait until completions have > been reaped" and if the application actually was tracking outstanding > completions this wouldn't make a lot of sense. Wouldn't it be simpler to just return an ERR_PTR with the appropriate return code rather than move all that code around? -ben > NOTE: > > the man page seems to imply that the current behaviour (-EAGAIN on allocation > failure) has always been the case. I don't think it makes a lot of sense, but > this should probably be discussed more widely in case applications have somehow > come to rely on the current behaviour... > > Signed-off-by: Kent Overstreet > Cc: Benjamin LaHaise > Cc: Zach Brown > Cc: Jeff Moyer > Cc: Jens Axboe > Cc: Slava Pestov > --- > fs/aio.c | 26 +++++++++++++------------- > 1 file changed, 13 insertions(+), 13 deletions(-) > > diff --git a/fs/aio.c b/fs/aio.c > index 733750096b..556547044b 100644 > --- a/fs/aio.c > +++ b/fs/aio.c > @@ -933,23 +933,14 @@ static inline struct kiocb *aio_get_req(struct kioctx *ctx) > { > struct kiocb *req; > > - if (!get_reqs_available(ctx)) { > - user_refill_reqs_available(ctx); > - if (!get_reqs_available(ctx)) > - return NULL; > - } > - > req = kmem_cache_alloc(kiocb_cachep, GFP_KERNEL|__GFP_ZERO); > if (unlikely(!req)) > - goto out_put; > + return NULL; > > percpu_ref_get(&ctx->reqs); > > req->ki_ctx = ctx; > return req; > -out_put: > - put_reqs_available(ctx, 1); > - return NULL; > } > > static void kiocb_free(struct kiocb *req) > @@ -1489,9 +1480,17 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, > return -EINVAL; > } > > + if (!get_reqs_available(ctx)) { > + user_refill_reqs_available(ctx); > + if (!get_reqs_available(ctx)) > + return -EAGAIN; > + } > + > req = aio_get_req(ctx); > - if (unlikely(!req)) > - return -EAGAIN; > + if (unlikely(!req)) { > + ret = -ENOMEM; > + goto out_put; > + } > > req->ki_filp = fget(iocb->aio_fildes); > if (unlikely(!req->ki_filp)) { > @@ -1533,9 +1532,10 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, > > return 0; > out_put_req: > - put_reqs_available(ctx, 1); > percpu_ref_put(&ctx->reqs); > kiocb_free(req); > +out_put: > + put_reqs_available(ctx, 1); > return ret; > } > > -- > 2.1.1 -- "Thought is the essence of where you are now." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/