bcachefs: Fix check_path() across subvolumes

Checking of directory structure across subvolumes was broken - we need
to look up the snapshot ID of the parent subvolume when crossing subvol
boundaries.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index 208bf6df82b5fcf2eefb75b47ff4f96d07487831..826a3577ee9318c115b1a7751eddf6b1e528af04 100644 (file)
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -1050,6 +1050,8 @@ static int inode_backpointer_exists(struct btree_trans *trans,
 {
        struct btree_iter iter;
        struct bkey_s_c k;
+       u32 target_subvol, target_snapshot;
+       u64 target_inum;
        int ret;
 
        bch2_trans_iter_init(trans, &iter, BTREE_ID_dirents,
@@ -1061,7 +1063,15 @@ static int inode_backpointer_exists(struct btree_trans *trans,
        if (k.k->type != KEY_TYPE_dirent)
                goto out;
 
-       ret = le64_to_cpu(bkey_s_c_to_dirent(k).v->d_inum) == inode->bi_inum;
+       ret = __bch2_dirent_read_target(trans, bkey_s_c_to_dirent(k),
+                                       &target_subvol,
+                                       &target_snapshot,
+                                       &target_inum,
+                                       true);
+       if (ret)
+               goto out;
+
+       ret = target_inum == inode->bi_inum;
 out:
        bch2_trans_iter_exit(trans, &iter);
        return ret;
@@ -1754,7 +1764,17 @@ static int check_path(struct btree_trans *trans,
        snapshot = snapshot_t(c, snapshot)->equiv;
        p->nr = 0;
 
-       while (inode->bi_inum != BCACHEFS_ROOT_INO) {
+       while (!(inode->bi_inum == BCACHEFS_ROOT_INO &&
+                inode->bi_subvol == BCACHEFS_ROOT_SUBVOL)) {
+               if (inode->bi_parent_subvol) {
+                       u64 inum;
+
+                       ret = subvol_lookup(trans, inode->bi_parent_subvol,
+                                           &snapshot, &inum);
+                       if (ret)
+                               break;
+               }
+
                ret = lockrestart_do(trans,
                        inode_backpointer_exists(trans, inode, snapshot));
                if (ret < 0)