btrfs scrub: bugfix: mirror_num off by one

Fix the mirror_num determination in scrub_stripe. The rest of the scrub code
did not use mirror_num for anything important and that error went unnoticed.
The nodatasum fixup patch of this set depends on a correct mirror_num.

Signed-off-by: Jan Schmidt <list.btrfs@jan-o-sch.net>

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index 221fd5c..59caf8f 100644 (file)
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -452,7 +452,7 @@ static void scrub_fixup(struct scrub_bio *sbio, int ix)
         * first find a good copy
         */
        for (i = 0; i < multi->num_stripes; ++i) {
-               if (i == sbio->spag[ix].mirror_num)
+               if (i + 1 == sbio->spag[ix].mirror_num)
                        continue;
 
                if (scrub_fixup_io(READ, multi->stripes[i].dev->bdev,
@@ -930,21 +930,21 @@ static noinline_for_stack int scrub_stripe(struct scrub_dev *sdev,
        if (map->type & BTRFS_BLOCK_GROUP_RAID0) {
                offset = map->stripe_len * num;
                increment = map->stripe_len * map->num_stripes;
-               mirror_num = 0;
+               mirror_num = 1;
        } else if (map->type & BTRFS_BLOCK_GROUP_RAID10) {
                int factor = map->num_stripes / map->sub_stripes;
                offset = map->stripe_len * (num / map->sub_stripes);
                increment = map->stripe_len * factor;
-               mirror_num = num % map->sub_stripes;
+               mirror_num = num % map->sub_stripes + 1;
        } else if (map->type & BTRFS_BLOCK_GROUP_RAID1) {
                increment = map->stripe_len;
-               mirror_num = num % map->num_stripes;
+               mirror_num = num % map->num_stripes + 1;
        } else if (map->type & BTRFS_BLOCK_GROUP_DUP) {
                increment = map->stripe_len;
-               mirror_num = num % map->num_stripes;
+               mirror_num = num % map->num_stripes + 1;
        } else {
                increment = map->stripe_len;
-               mirror_num = 0;
+               mirror_num = 1;
        }
 
        path = btrfs_alloc_path();