dm thin: update discard_granularity to reflect the thin-pool blocksize

DM thinp already checks whether the discard_granularity of the data
device is a factor of the thin-pool block size.  But when using the
dm-thin-pool's discard passdown support, DM thinp was not selecting the
max of the underlying data device's discard_granularity and the
thin-pool's block size.

Update set_discard_limits() to set discard_granularity to the max of
these values.  This enables blkdev_issue_discard() to properly align the
discards that are sent to the DM thin device on a full block boundary.
As such each discard will now cover an entire DM thin-pool block and the
block will be reclaimed.

Reported-by: Zdenek Kabelac <[email protected]>
Signed-off-by: Lukas Czerner <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>
Cc: [email protected]

0 files changed, 0 insertions, 0 deletions