md: add proper merge_bvec handling to RAID0 and Linear.
These personalities currently set a max request size of one page
when any member device has a merge_bvec_fn because they don't
bother to call that function.
This causes extra works in splitting and combining requests.
So make the extra effort to call the merge_bvec_fn when it exists
so that we end up with larger requests out the bottom.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid0.h b/drivers/md/raid0.h
index 0884bba..05539d9 100644
--- a/drivers/md/raid0.h
+++ b/drivers/md/raid0.h
@@ -4,13 +4,16 @@
struct strip_zone {
sector_t zone_end; /* Start of the next zone (in sectors) */
sector_t dev_start; /* Zone offset in real dev (in sectors) */
- int nb_dev; /* # of devices attached to the zone */
+ int nb_dev; /* # of devices attached to the zone */
};
struct r0conf {
- struct strip_zone *strip_zone;
- struct md_rdev **devlist; /* lists of rdevs, pointed to by strip_zone->dev */
- int nr_strip_zones;
+ struct strip_zone *strip_zone;
+ struct md_rdev **devlist; /* lists of rdevs, pointed to
+ * by strip_zone->dev */
+ int nr_strip_zones;
+ int has_merge_bvec; /* at least one member has
+ * a merge_bvec_fn */
};
#endif