Pankaj reports that starting with commit ad428cdb52 "dax: Check the
end of the block-device capacity with dax_direct_access()" device-mapper
no longer allows dax operation. This results from the stricter checks in
__bdev_dax_supported() that validate that the start and end of a
block-device map to the same 'pagemap' instance.
Teach the dax-core and device-mapper to validate the 'pagemap' on a
per-target basis. This is accomplished by refactoring the
bdev_dax_supported() internals into generic_fsdax_supported() which
takes a sector range to validate. Consequently generic_fsdax_supported()
is suitable to be used in a device-mapper ->iterate_devices() callback.
A new ->dax_supported() operation is added to allow composite devices to
split and route upper-level bdev_dax_supported() requests.
Fixes: ad428cdb52 ("dax: Check the end of the block-device...")
Cc: <[email protected]>
Cc: Ira Weiny <[email protected]>
Cc: Dave Jiang <[email protected]>
Cc: Keith Busch <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Vishal Verma <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reported-by: Pankaj Gupta <[email protected]>
Reviewed-by: Pankaj Gupta <[email protected]>
Tested-by: Pankaj Gupta <[email protected]>
Tested-by: Vaibhav Jain <[email protected]>
Reviewed-by: Mike Snitzer <[email protected]>
Signed-off-by: Dan Williams <[email protected]>
7bf7eac8d6