bcachefs: Check for unlinked, non-empty dirs in check_inode()

We want to check for this early so it can be reattached if necessary in
check_unreachable_inodes(); better than letting it be deleted and having
the children reattached, losing their filenames.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/fsck.c

@@ -1083,6 +1083,23 @@ static int check_inode(struct btree_trans *trans,
 		do_update = true;
 	}
 
+	if (S_ISDIR(u.bi_mode) && (u.bi_flags & BCH_INODE_unlinked)) {
+		/* Check for this early so that check_unreachable_inode() will reattach it */
+
+		ret = bch2_empty_dir_snapshot(trans, k.k->p.offset, 0, k.k->p.snapshot);
+		if (ret && ret != -BCH_ERR_ENOTEMPTY_dir_not_empty)
+			goto err;
+
+		fsck_err_on(ret, trans, inode_dir_unlinked_but_not_empty,
+			    "dir unlinked but not empty\n%s",
+			    (printbuf_reset(&buf),
+			     bch2_inode_unpacked_to_text(&buf, &u),
+			     buf.buf));
+		u.bi_flags &= ~BCH_INODE_unlinked;
+		do_update = true;
+		ret = 0;
+	}
+
 	if ((u.bi_flags & (BCH_INODE_i_size_dirty|BCH_INODE_unlinked)) &&
 	    bch2_key_has_snapshot_overwrites(trans, BTREE_ID_inodes, k.k->p)) {
 		struct bpos new_min_pos;

fs/bcachefs/sb-errors_format.h

@@ -221,6 +221,7 @@ enum bch_fsck_flags {
 	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_dir_unlinked_but_not_empty,			286,	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)	\
@@ -297,7 +298,7 @@ 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,							286,	0)
+	x(MAX,							287,	0)
 
 enum bch_sb_error_id {
 #define x(t, n, ...) BCH_FSCK_ERR_##t = n,