Btrfs: Simplify device selection for mirrored reads

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

1 files changed, 7 insertions, 16 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 460240706505..107fc74c3ab8 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1029,19 +1029,8 @@ again:
                 else if (mirror_num) {
                         stripe_index = mirror_num - 1;
                 } else {
-                        int i;
-                        u64 least = (u64)-1;
-                        struct btrfs_device *cur;
-
-                        for (i = 0; i < map->num_stripes; i++) {
-                                cur = map->stripes[i].dev;
-                                spin_lock(&cur->io_lock);
-                                if (cur->total_ios < least) {
-                                        least = cur->total_ios;
-                                        stripe_index = i;
-                                }
-                                spin_unlock(&cur->io_lock);
-                        }
+                        u64 orig_stripe_nr = stripe_nr;
+                        stripe_index = do_div(orig_stripe_nr, num_stripes);
                 }
         } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
                 if (rw & (1 << BIO_RW))
@@ -1050,7 +1039,6 @@ again:
                         stripe_index = mirror_num - 1;
         } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
                 int factor = map->num_stripes / map->sub_stripes;
-                int orig_stripe_nr = stripe_nr;
 
                 stripe_index = do_div(stripe_nr, factor);
                 stripe_index *= map->sub_stripes;
@@ -1059,8 +1047,11 @@ again:
                         num_stripes = map->sub_stripes;
                 else if (mirror_num)
                         stripe_index += mirror_num - 1;
-                else
-                        stripe_index += orig_stripe_nr % map->sub_stripes;
+                else {
+                        u64 orig_stripe_nr = stripe_nr;
+                        stripe_index += do_div(orig_stripe_nr,
+                                               map->sub_stripes);
+                }
         } else {
                 /*
                  * after this do_div call, stripe_nr is the number of stripes