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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>
This commit is contained in:
Toshi Kani 2016-06-28 13:37:16 -06:00 committed by Mike Snitzer
parent beec25b457
commit f6e629bd23
1 changed files with 8 additions and 0 deletions
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8
drivers/md/dm-snap.c
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@ -2301,6 +2301,13 @@ static int origin_map(struct dm_target *ti, struct bio *bio)
return do_origin(o->dev, 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' * Set the target "max_io_len" field to the minimum of all the snapshots'
* chunk sizes. * chunk sizes.
@ -2360,6 +2367,7 @@ static struct target_type origin_target = {
.postsuspend = origin_postsuspend, .postsuspend = origin_postsuspend,
.status = origin_status, .status = origin_status,
.iterate_devices = origin_iterate_devices, .iterate_devices = origin_iterate_devices,
.direct_access = origin_direct_access,
}; };
static struct target_type snapshot_target = { static struct target_type snapshot_target = {