bcachefs: Check for directories with no backpointers

It's legal for regular files to have missing backpointers (due to
hardlinks), and fsck should automatically add them, but for directories
this is an error that should be flagged.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

diff --git a/fs/bcachefs/fsck.c b/fs/bcachefs/fsck.c
index f0d6696c4df6162aeec3d47b8ac01c7aca6af995..d2aa6a5bc973e6ad744647a652a31cc335d1a158 100644 (file)
--- a/fs/bcachefs/fsck.c
+++ b/fs/bcachefs/fsck.c
@@ -1826,6 +1826,21 @@ static int check_dirent_inode_dirent(struct btree_trans *trans,
        if (inode_points_to_dirent(target, d))
                return 0;
 
+       if (!target->bi_dir &&
+           !target->bi_dir_offset) {
+               fsck_err_on(S_ISDIR(target->bi_mode),
+                           trans, inode_dir_missing_backpointer,
+                           "directory with missing backpointer\n%s",
+                           (bch2_bkey_val_to_text(&buf, c, d.s_c),
+                            prt_printf(&buf, "\n  "),
+                            bch2_inode_unpacked_to_text(&buf, target),
+                            buf.buf));
+
+               target->bi_dir          = d.k->p.inode;
+               target->bi_dir_offset   = d.k->p.offset;
+               return __bch2_fsck_write_inode(trans, target, target_snapshot);
+       }
+
        if (bch2_inode_should_have_bp(target) &&
            !fsck_err(trans, inode_wrong_backpointer,
                      "dirent points to inode that does not point back:\n  %s",
@@ -1835,13 +1850,6 @@ static int check_dirent_inode_dirent(struct btree_trans *trans,
                       buf.buf)))
                goto err;
 
-       if (!target->bi_dir &&
-           !target->bi_dir_offset) {
-               target->bi_dir          = d.k->p.inode;
-               target->bi_dir_offset   = d.k->p.offset;
-               return __bch2_fsck_write_inode(trans, target, target_snapshot);
-       }
-
        struct bkey_s_c_dirent bp_dirent = dirent_get_by_pos(trans, &bp_iter,
                              SPOS(target->bi_dir, target->bi_dir_offset, target_snapshot));
        ret = bkey_err(bp_dirent);

diff --git a/fs/bcachefs/sb-errors_format.h b/fs/bcachefs/sb-errors_format.h
index b4024870b65e88b0faad566df838957622122c62..fc3d31ed5975c8a7ee2d4ef60cb3cff577dac29a 100644 (file)
--- a/fs/bcachefs/sb-errors_format.h
+++ b/fs/bcachefs/sb-errors_format.h
@@ -219,6 +219,7 @@ enum bch_fsck_flags {
        x(inode_i_sectors_wrong,                                204,    FSCK_AUTOFIX)   \
        x(inode_dir_wrong_nlink,                                205,    FSCK_AUTOFIX)   \
        x(inode_dir_multiple_links,                             206,    FSCK_AUTOFIX)   \
+       x(inode_dir_missing_backpointer,                        284,    FSCK_AUTOFIX)   \
        x(inode_multiple_links_but_nlink_0,                     207,    FSCK_AUTOFIX)   \
        x(inode_wrong_backpointer,                              208,    FSCK_AUTOFIX)   \
        x(inode_wrong_nlink,                                    209,    FSCK_AUTOFIX)   \
@@ -295,7 +296,7 @@ enum bch_fsck_flags {
        x(accounting_key_replicas_devs_unsorted,                280,    FSCK_AUTOFIX)   \
        x(accounting_key_version_0,                             282,    FSCK_AUTOFIX)   \
        x(logged_op_but_clean,                                  283,    FSCK_AUTOFIX)   \
-       x(MAX,                                                  284,    0)
+       x(MAX,                                                  285,    0)
 
 enum bch_sb_error_id {
 #define x(t, n, ...) BCH_FSCK_ERR_##t = n,