From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id ABA99211EB2B9 for ; Mon, 10 Jun 2019 12:28:55 -0700 (PDT) Date: Mon, 10 Jun 2019 15:28:03 -0400 From: Mike Snitzer Subject: Re: [PATCH v11 4/7] dm: enable synchronous dax Message-ID: <20190610192803.GA29002@redhat.com> References: <20190610090730.8589-1-pagupta@redhat.com> <20190610090730.8589-5-pagupta@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190610090730.8589-5-pagupta@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Pankaj Gupta Cc: cohuck@redhat.com, jack@suse.cz, kvm@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, david@fromorbit.com, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, dm-devel@redhat.com, adilger.kernel@dilger.ca, zwisler@kernel.org, aarcange@redhat.com, jstaron@google.com, linux-nvdimm@lists.01.org, david@redhat.com, willy@infradead.org, hch@infradead.org, linux-acpi@vger.kernel.org, linux-ext4@vger.kernel.org, lenb@kernel.org, kilobyte@angband.pl, rdunlap@infradead.org, riel@surriel.com, yuval.shaia@oracle.com, stefanha@redhat.com, pbonzini@redhat.com, lcapitulino@redhat.com, kwolf@redhat.com, nilal@redhat.com, tytso@mit.edu, xiaoguangrong.eric@gmail.com, darrick.wong@oracle.com, rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, imammedo@redhat.com List-ID: On Mon, Jun 10 2019 at 5:07am -0400, Pankaj Gupta wrote: > This patch sets dax device 'DAXDEV_SYNC' flag if all the target > devices of device mapper support synchrononous DAX. If device > mapper consists of both synchronous and asynchronous dax devices, > we don't set 'DAXDEV_SYNC' flag. > > Signed-off-by: Pankaj Gupta > --- > drivers/md/dm-table.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > index 350cf0451456..c5160d846fe6 100644 > --- a/drivers/md/dm-table.c > +++ b/drivers/md/dm-table.c > @@ -890,10 +890,17 @@ static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev, > start, len); > } > > +static int device_synchronous(struct dm_target *ti, struct dm_dev *dev, > + sector_t start, sector_t len, void *data) > +{ > + return dax_synchronous(dev->dax_dev); > +} > + > bool dm_table_supports_dax(struct dm_table *t, int blocksize) > { > struct dm_target *ti; > unsigned i; > + bool dax_sync = true; > > /* Ensure that all targets support DAX. */ > for (i = 0; i < dm_table_get_num_targets(t); i++) { > @@ -906,7 +913,14 @@ bool dm_table_supports_dax(struct dm_table *t, int blocksize) > !ti->type->iterate_devices(ti, device_supports_dax, > &blocksize)) > return false; > + > + /* Check devices support synchronous DAX */ > + if (dax_sync && > + !ti->type->iterate_devices(ti, device_synchronous, NULL)) > + dax_sync = false; > } > + if (dax_sync) > + set_dax_synchronous(t->md->dax_dev); > > return true; > } > -- > 2.20.1 > dm_table_supports_dax() is called multiple times (from dm_table_set_restrictions and dm_table_determine_type). It is strange to have a getter have a side-effect of being a setter too. Overloading like this could get you in trouble in the future. Are you certain this is what you want? Or would it be better to refactor dm_table_supports_dax() to take an iterate_devices_fn arg and have callers pass the appropriate function? Then have dm_table_set_restrictions() caller do: if (dm_table_supports_dax(t, device_synchronous, NULL)) set_dax_synchronous(t->md->dax_dev); (NULL arg implies dm_table_supports_dax() refactoring would take a int *data pointer rather than int type). Mike _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm