Commit f6e629bd authored Jun 28, 2016 by Toshi Kani Committed by Mike Snitzer Jul 20, 2016

dm snap: add fake origin_direct_access



dax-capable mapped-device is marked as DM_TYPE_DAX_BIO_BASED,
which supports both dax and bio-based operations.  dm-snap
needs to work with dax-capable device when bio-based operation
is used.

Add fake origin_direct_access() to origin device so that its
origin device is also marked as DM_TYPE_DAX_BIO_BASED for
dax-capable device.  This allows to extend target's DM table.
dm-snap works normally when bio-based operation is used.

dm-snap does not support dax operation, and mount with dax
option to a target device or snapshot device fails.

Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

parent beec25b4

drivers/md/dm-snap.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -2301,6 +2301,13 @@ static int origin_map(struct dm_target ti, struct bio bio)
		return do_origin(o->dev, bio);
		}

		static long origin_direct_access(struct dm_target *ti, sector_t sector,
		void __pmem *kaddr, pfn_t pfn, long size)
		{
		DMWARN("device does not support dax.");
		return -EIO;
		}

		/*
		* Set the target "max_io_len" field to the minimum of all the snapshots'
		* chunk sizes.
		@@ -2360,6 +2367,7 @@ static struct target_type origin_target = {
		.postsuspend = origin_postsuspend,
		.status = origin_status,
		.iterate_devices = origin_iterate_devices,
		.direct_access = origin_direct_access,
		};

		static struct target_type snapshot_target = {

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