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Commit f6e629bd authored by Toshi Kani's avatar Toshi Kani Committed by Mike Snitzer
Browse files

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: default avatarToshi 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: default avatarMike 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 = {