Btrfs: sort raid_map before adding tgtdev stripes

It can avoid complex calculation of real stripes in sort,
moreover, we can clean up code of sorting tgtdev_map because it
will be in order initially.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 8 insertions, 14 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0d9bfebdaa4c..711ce38543a1 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4876,18 +4876,17 @@ static inline int parity_smaller(u64 a, u64 b)
 }
 
 /* Bubble-sort the stripe set to put the parity/syndrome stripes last */
-static void sort_parity_stripes(struct btrfs_bio *bbio, u64 *raid_map)
+static void sort_parity_stripes(struct btrfs_bio *bbio, u64 *raid_map,
+                                int num_stripes)
 {
         struct btrfs_bio_stripe s;
-        int real_stripes = bbio->num_stripes - bbio->num_tgtdevs;
         int i;
         u64 l;
         int again = 1;
-        int m;
 
         while (again) {
                 again = 0;
-                for (i = 0; i < real_stripes - 1; i++) {
+                for (i = 0; i < num_stripes - 1; i++) {
                         if (parity_smaller(raid_map[i], raid_map[i+1])) {
                                 s = bbio->stripes[i];
                                 l = raid_map[i];
@@ -4896,13 +4895,6 @@ static void sort_parity_stripes(struct btrfs_bio *bbio, u64 *raid_map)
                                 bbio->stripes[i+1] = s;
                                 raid_map[i+1] = l;
 
-                                if (bbio->tgtdev_map) {
-                                        m = bbio->tgtdev_map[i];
-                                        bbio->tgtdev_map[i] =
-                                                        bbio->tgtdev_map[i + 1];
-                                        bbio->tgtdev_map[i + 1] = m;
-                                }
-
                                 again = 1;
                         }
                 }
@@ -5340,6 +5332,9 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
         if (rw & (REQ_WRITE | REQ_GET_READ_MIRRORS))
                 max_errors = btrfs_chunk_max_errors(map);
 
+        if (raid_map)
+                sort_parity_stripes(bbio, raid_map, num_stripes);
+
         tgtdev_indexes = 0;
         if (dev_replace_is_ongoing && (rw & (REQ_WRITE | REQ_DISCARD)) &&
             dev_replace->tgtdev != NULL) {
@@ -5443,10 +5438,9 @@ static int __btrfs_map_block(struct btrfs_fs_info *fs_info, int rw,
                 bbio->stripes[0].physical = physical_to_patch_in_first_stripe;
                 bbio->mirror_num = map->num_stripes + 1;
         }
-        if (raid_map) {
-                sort_parity_stripes(bbio, raid_map);
+
+        if (raid_map_ret)
                 *raid_map_ret = raid_map;
-        }
 out:
         if (dev_replace_is_ongoing)
                 btrfs_dev_replace_unlock(dev_replace);