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-rw-r--r--drivers/md/dm.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 98866e725f25..f7eb3d2964f3 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1039,15 +1039,18 @@ static sector_t max_io_len(struct dm_target *ti, sector_t sector)
sector_t max_len;
/*
- * Does the target need to split even further?
- * - q->limits.chunk_sectors reflects ti->max_io_len so
- * blk_max_size_offset() provides required splitting.
- * - blk_max_size_offset() also respects q->limits.max_sectors
+ * Does the target need to split IO even further?
+ * - varied (per target) IO splitting is a tenet of DM; this
+ * explains why stacked chunk_sectors based splitting via
+ * blk_max_size_offset() isn't possible here. So pass in
+ * ti->max_io_len to override stacked chunk_sectors.
*/
- max_len = blk_max_size_offset(ti->table->md->queue,
- target_offset);
- if (len > max_len)
- len = max_len;
+ if (ti->max_io_len) {
+ max_len = blk_max_size_offset(ti->table->md->queue,
+ target_offset, ti->max_io_len);
+ if (len > max_len)
+ len = max_len;
+ }
return len;
}