dm: support non power of two target max_io_len

Remove the restriction that limits a target's specified maximum incoming
I/O size to be a power of 2.

Rename this setting from 'split_io' to the less-ambiguous 'max_io_len'.
Change it from sector_t to uint32_t, which is plenty big enough, and
introduce a wrapper function dm_set_target_max_io_len() to set it.
Use sector_div() to process it now that it is not necessarily a power of 2.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/md/dm-raid1.c b/drivers/md/dm-raid1.c
index b58b7a33914a..819ccba65912 100644
--- a/drivers/md/dm-raid1.c
+++ b/drivers/md/dm-raid1.c
@@ -1081,7 +1081,11 @@ static int mirror_ctr(struct dm_target *ti, unsigned int argc, char **argv)
         }
 
         ti->private = ms;
-        ti->split_io = dm_rh_get_region_size(ms->rh);
+
+        r = dm_set_target_max_io_len(ti, dm_rh_get_region_size(ms->rh));
+        if (r)
+                goto err_free_context;
+
         ti->num_flush_requests = 1;
         ti->num_discard_requests = 1;
         ti->discard_zeroes_data_unsupported = 1;