From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756826AbbAZR6i (ORCPT ); Mon, 26 Jan 2015 12:58:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:55530 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756230AbbAZR6g (ORCPT ); Mon, 26 Jan 2015 12:58:36 -0500 From: Jeff Moyer To: Ming Lei Cc: linux-kernel@vger.kernel.org, Dave Kleikamp , Jens Axboe , Zach Brown , Christoph Hellwig , Maxim Patlasov , Andrew Morton , Alexander Viro , Benjamin LaHaise Subject: Re: [PATCH v2 3/4] block: loop: introduce 'use_aio' sysfs file References: <1421163888-21452-1-git-send-email-ming.lei@canonical.com> <1421163888-21452-4-git-send-email-ming.lei@canonical.com> X-PGP-KeyID: 1F78E1B4 X-PGP-CertKey: F6FE 280D 8293 F72C 65FD 5A58 1FF8 A7CA 1F78 E1B4 X-PCLoadLetter: What the f**k does that mean? Date: Mon, 26 Jan 2015 12:57:53 -0500 In-Reply-To: <1421163888-21452-4-git-send-email-ming.lei@canonical.com> (Ming Lei's message of "Tue, 13 Jan 2015 23:44:47 +0800") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ming Lei writes: > So that users can control if kernel aio is used to submit I/O. How would a user know to choose aio or, um, /not/ aio? At the very least, documentation is required for this. I'd rather see the option disappear completely, though. Cheers, Jeff > > Signed-off-by: Ming Lei > --- > drivers/block/loop.c | 33 +++++++++++++++++++++++++++++++++ > drivers/block/loop.h | 1 + > 2 files changed, 34 insertions(+) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index d1f168b..47af456 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -659,6 +659,38 @@ static ssize_t loop_attr_partscan_show(struct loop_device *lo, char *buf) > return sprintf(buf, "%s\n", partscan ? "1" : "0"); > } > > +static ssize_t loop_attr_do_show_use_aio(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + struct gendisk *disk = dev_to_disk(dev); > + struct loop_device *lo = disk->private_data; > + > + return sprintf(buf, "%s\n", lo->use_aio ? "1" : "0"); > +} > + > +ssize_t loop_attr_do_store_use_aio(struct device *dev, > + struct device_attribute *attr, const char *buf, > + size_t count) > +{ > + struct gendisk *disk = dev_to_disk(dev); > + struct loop_device *lo = disk->private_data; > + int err; > + unsigned long v; > + > + err = kstrtoul(buf, 10, &v); > + if (err < 0) > + return err; > + if (v) > + lo->use_aio = true; > + else > + lo->use_aio = false; > + return count; > +} > + > +static struct device_attribute loop_attr_use_aio = > + __ATTR(use_aio, S_IRUGO | S_IWUSR, loop_attr_do_show_use_aio, > + loop_attr_do_store_use_aio); > + > LOOP_ATTR_RO(backing_file); > LOOP_ATTR_RO(offset); > LOOP_ATTR_RO(sizelimit); > @@ -671,6 +703,7 @@ static struct attribute *loop_attrs[] = { > &loop_attr_sizelimit.attr, > &loop_attr_autoclear.attr, > &loop_attr_partscan.attr, > + &loop_attr_use_aio.attr, > NULL, > }; > > diff --git a/drivers/block/loop.h b/drivers/block/loop.h > index 301c27f..15049e9 100644 > --- a/drivers/block/loop.h > +++ b/drivers/block/loop.h > @@ -57,6 +57,7 @@ struct loop_device { > struct list_head write_cmd_head; > struct work_struct write_work; > bool write_started; > + bool use_aio; > int lo_state; > struct mutex lo_ctl_mutex;