From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:38080 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752427AbeFZSR2 (ORCPT ); Tue, 26 Jun 2018 14:17:28 -0400 Date: Tue, 26 Jun 2018 14:17:26 -0400 From: Mike Snitzer To: Ross Zwisler Cc: Toshi Kani , dm-devel@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-xfs@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3 3/3] dm: prevent DAX mounts if not supported Message-ID: <20180626181726.GA6630@redhat.com> References: <20180626175932.8899-1-ross.zwisler@linux.intel.com> <20180626175932.8899-4-ross.zwisler@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180626175932.8899-4-ross.zwisler@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Jun 26 2018 at 1:59pm -0400, Ross Zwisler wrote: > Currently device_supports_dax() just checks to see if the QUEUE_FLAG_DAX > flag is set on the device's request queue to decide whether or not the > device supports filesystem DAX. Really we should be using > bdev_dax_supported() like filesystems do at mount time. This performs > other tests like checking to make sure the dax_direct_access() path works. > > Conditionally set QUEUE_FLAG_DAX on the DM device's request queue based on > whether all underlying devices support DAX. Now that bdev_dax_supported() > explicitly checks for this flag, this will ensure that filesystems built > upon DM devices will only be able to mount with DAX if all underlying > devices also support DAX. > > Signed-off-by: Ross Zwisler > Fixes: commit 545ed20e6df6 ("dm: add infrastructure for DAX support") > Cc: stable@vger.kernel.org > --- > drivers/md/dm-ioctl.c | 5 +++++ > drivers/md/dm-table.c | 7 +++---- > drivers/md/dm.c | 3 +-- > include/linux/device-mapper.h | 5 +++++ > 4 files changed, 14 insertions(+), 6 deletions(-) > > diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c > index b810ea77e6b1..0055bdbee5b1 100644 > --- a/drivers/md/dm-ioctl.c > +++ b/drivers/md/dm-ioctl.c > @@ -1350,6 +1350,11 @@ static int table_load(struct file *filp, struct dm_ioctl *param, size_t param_si > goto err_unlock_md_type; > } > > + if (dm_table_supports_dax(t)) > + blk_queue_flag_set(QUEUE_FLAG_DAX, md->queue); > + else > + blk_queue_flag_clear(QUEUE_FLAG_DAX, md->queue); > + > dm_unlock_md_type(md); > > /* stage inactive table */ This should occur in drivers/md/dm-table.c:dm_table_set_restrictions(). Which already has: if (dm_table_supports_dax(t)) blk_queue_flag_set(QUEUE_FLAG_DAX, q); So it just needs tweaking. > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > index 938766794c2e..c673b4a51fb2 100644 > --- a/drivers/md/dm-table.c > +++ b/drivers/md/dm-table.c > @@ -885,12 +885,10 @@ EXPORT_SYMBOL_GPL(dm_table_set_type); > static int device_supports_dax(struct dm_target *ti, struct dm_dev *dev, > sector_t start, sector_t len, void *data) > { > - struct request_queue *q = bdev_get_queue(dev->bdev); > - > - return q && blk_queue_dax(q); > + return bdev_dax_supported(dev->bdev, PAGE_SIZE); > } > > -static bool dm_table_supports_dax(struct dm_table *t) > +bool dm_table_supports_dax(struct dm_table *t) > { > struct dm_target *ti; > unsigned i; > @@ -909,6 +907,7 @@ static bool dm_table_supports_dax(struct dm_table *t) > > return true; > } > +EXPORT_SYMBOL_GPL(dm_table_supports_dax); > > static bool dm_table_does_not_support_partial_completion(struct dm_table *t); > Which would mean you don't need to export dm_table_supports_dax(). > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index e65429a29c06..bef5a3f243ed 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -1056,8 +1056,7 @@ static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff, > if (len < 1) > goto out; > nr_pages = min(len, nr_pages); > - if (ti->type->direct_access) > - ret = ti->type->direct_access(ti, pgoff, nr_pages, kaddr, pfn); > + ret = ti->type->direct_access(ti, pgoff, nr_pages, kaddr, pfn); > > out: > dm_put_live_table(md, srcu_idx); > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h > index 6fb0808e87c8..45ea9e1f9af9 100644 > --- a/include/linux/device-mapper.h > +++ b/include/linux/device-mapper.h > @@ -461,6 +461,11 @@ void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callback > */ > void dm_table_set_type(struct dm_table *t, enum dm_queue_mode type); > > +/* > + * Check to see if this target type and all table devices support DAX. > + */ > +bool dm_table_supports_dax(struct dm_table *t); > + > /* > * Finally call this to make the table ready for use. > */ Nor do you need to publish the dm_table_supports_dax() interface via include/linux/device-mapper.h