tree b3f82d7b0a6c34c4d449debd2d1d242bdbf84b56
parent bbdd304cf66fbf2b4b2d28418dc619d443635e83
author Martin K. Petersen <martin.petersen@oracle.com> 1305707855 +0200
committer Jens Axboe <jaxboe@fusionio.com> 1305707855 +0200

block: Fix discard topology stacking and reporting

In some cases we would end up stacking discard_zeroes_data incorrectly.
Fix this by enabling the feature by default for stacking drivers and
clearing it for low-level drivers. Incorporating a device that does not
support dzd will then cause the feature to be disabled in the stacking
driver.

Also ensure that the maximum discard value does not overflow when
exported in sysfs and return 0 in the alignment and dzd fields for
devices that don't support discard.

Reported-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>