Btrfs: Tune stripe selection for raid1 and raid10

Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 57ab755..6d8dd44 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1509,17 +1509,17 @@ again:
        if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
                if (unplug_page || (rw & (1 << BIO_RW)))
                        num_stripes = map->num_stripes;
-               else if (mirror_num) {
+               else if (mirror_num)
                        stripe_index = mirror_num - 1;
-               } else {
-                       u64 orig_stripe_nr = stripe_nr;
-                       stripe_index = do_div(orig_stripe_nr, num_stripes);
-               }
+               else
+                       stripe_index = current->pid % map->num_stripes;
+
        } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
                if (rw & (1 << BIO_RW))
                        num_stripes = map->num_stripes;
                else if (mirror_num)
                        stripe_index = mirror_num - 1;
+
        } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
                int factor = map->num_stripes / map->sub_stripes;
 
@@ -1530,11 +1530,8 @@ again:
                        num_stripes = map->sub_stripes;
                else if (mirror_num)
                        stripe_index += mirror_num - 1;
-               else {
-                       u64 orig_stripe_nr = stripe_nr;
-                       stripe_index += do_div(orig_stripe_nr,
-                                              map->sub_stripes);
-               }
+               else
+                       stripe_index += current->pid % map->sub_stripes;
        } else {
                /*
                 * after this do_div call, stripe_nr is the number of stripes