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>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0d9bfebdaa4c22cb012e73b15e2ab8818d1bb49e..711ce38543a10b9ce654af108711180bd59fc842 100644 (file)
--- 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);