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Date: Fri, 10 May 2019 21:23:17 -0400 (EDT) From: Pankaj Gupta <pagupta@...hat.com> To: Dan Williams <dan.j.williams@...el.com> Cc: cohuck@...hat.com, Jan Kara <jack@...e.cz>, KVM list <kvm@...r.kernel.org>, "Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, david <david@...morbit.com>, Qemu Developers <qemu-devel@...gnu.org>, virtualization@...ts.linux-foundation.org, Andreas Dilger <adilger.kernel@...ger.ca>, Ross Zwisler <zwisler@...nel.org>, Andrea Arcangeli <aarcange@...hat.com>, Dave Jiang <dave.jiang@...el.com>, jstaron@...gle.com, linux-nvdimm <linux-nvdimm@...ts.01.org>, Vishal L Verma <vishal.l.verma@...el.com>, David Hildenbrand <david@...hat.com>, Matthew Wilcox <willy@...radead.org>, Christoph Hellwig <hch@...radead.org>, Linux ACPI <linux-acpi@...r.kernel.org>, jmoyer <jmoyer@...hat.com>, linux-ext4 <linux-ext4@...r.kernel.org>, Len Brown <lenb@...nel.org>, Adam Borowski <kilobyte@...band.pl>, Rik van Riel <riel@...riel.com>, yuval shaia <yuval.shaia@...cle.com>, Stefan Hajnoczi <stefanha@...hat.com>, Paolo Bonzini <pbonzini@...hat.com>, lcapitulino@...hat.com, Kevin Wolf <kwolf@...hat.com>, Nitesh Narayan Lal <nilal@...hat.com>, Theodore Ts'o <tytso@....edu>, Xiao Guangrong <xiaoguangrong.eric@...il.com>, "Darrick J. Wong" <darrick.wong@...cle.com>, "Rafael J. Wysocki" <rjw@...ysocki.net>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, linux-xfs <linux-xfs@...r.kernel.org>, linux-fsdevel <linux-fsdevel@...r.kernel.org>, Igor Mammedov <imammedo@...hat.com> Subject: Re: [Qemu-devel] [PATCH v8 3/6] libnvdimm: add dax_dev sync flag > > > > > > > > This patch adds 'DAXDEV_SYNC' flag which is set > > > > for nd_region doing synchronous flush. This later > > > > is used to disable MAP_SYNC functionality for > > > > ext4 & xfs filesystem for devices don't support > > > > synchronous flush. > > > > > > > > Signed-off-by: Pankaj Gupta <pagupta@...hat.com> > > > > --- > > > > drivers/dax/bus.c | 2 +- > > > > drivers/dax/super.c | 13 ++++++++++++- > > > > drivers/md/dm.c | 3 ++- > > > > drivers/nvdimm/pmem.c | 5 ++++- > > > > drivers/nvdimm/region_devs.c | 7 +++++++ > > > > include/linux/dax.h | 8 ++++++-- > > > > include/linux/libnvdimm.h | 1 + > > > > 7 files changed, 33 insertions(+), 6 deletions(-) > > > [..] > > > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > > > > index 043f0761e4a0..ee007b75d9fd 100644 > > > > --- a/drivers/md/dm.c > > > > +++ b/drivers/md/dm.c > > > > @@ -1969,7 +1969,8 @@ static struct mapped_device *alloc_dev(int minor) > > > > sprintf(md->disk->disk_name, "dm-%d", minor); > > > > > > > > if (IS_ENABLED(CONFIG_DAX_DRIVER)) { > > > > - dax_dev = alloc_dax(md, md->disk->disk_name, > > > > &dm_dax_ops); > > > > + dax_dev = alloc_dax(md, md->disk->disk_name, > > > > &dm_dax_ops, > > > > + > > > > DAXDEV_F_SYNC); > > > > > > Apologies for not realizing this until now, but this is broken. > > > Imaging a device-mapper configuration composed of both 'async' > > > virtio-pmem and 'sync' pmem. The 'sync' flag needs to be unified > > > across all members. I would change this argument to '0' and then > > > arrange for it to be set at dm_table_supports_dax() time after > > > validating that all components support synchronous dax. > > > > o.k. Need to set 'DAXDEV_F_SYNC' flag after verifying all the target > > components support synchronous DAX. > > > > Just a question, If device mapper configuration have composed of both > > virtio-pmem or pmem devices, we want to configure device mapper for async > > flush? > > If it's composed of both then, yes, it needs to be async flush at the > device-mapper level. Otherwise MAP_SYNC will succeed and fail to > trigger fsync on the host file when necessary for the virtio-pmem > backed portion of the device-mapper device. o.k. Agree. Thanks you, Pankaj > >
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