xfs: repair problems in CoW forks

Try to repair errors that we see in file CoW forks so that we don't do
stupid things like remap garbage into a file.  There's not a lot we can
do with the COW fork -- the ondisk metadata record only that the COW
staging extents are owned by the refcount btree, which effectively means
that we can't reconstruct this incore structure from scratch.

Actually, this is even worse -- we can't touch written extents, because
those map space that are actively under writeback, and there's not much
to do with delalloc reservations.  Hence we can only detect crosslinked
unwritten extents and fix them by punching out the problematic parts and
replacing them with delalloc extents.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 37 insertions, 0 deletions

diff --git a/fs/xfs/scrub/off_bitmap.h b/fs/xfs/scrub/off_bitmap.h
new file mode 100644
index 000000000000..0d3f9e6c1aad
--- /dev/null
+++ b/fs/xfs/scrub/off_bitmap.h
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2022-2023 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_SCRUB_OFF_BITMAP_H__
+#define __XFS_SCRUB_OFF_BITMAP_H__
+
+/* Bitmaps, but for type-checked for xfs_fileoff_t */
+
+struct xoff_bitmap {
+	struct xbitmap64	offbitmap;
+};
+
+static inline void xoff_bitmap_init(struct xoff_bitmap *bitmap)
+{
+	xbitmap64_init(&bitmap->offbitmap);
+}
+
+static inline void xoff_bitmap_destroy(struct xoff_bitmap *bitmap)
+{
+	xbitmap64_destroy(&bitmap->offbitmap);
+}
+
+static inline int xoff_bitmap_set(struct xoff_bitmap *bitmap,
+		xfs_fileoff_t off, xfs_filblks_t len)
+{
+	return xbitmap64_set(&bitmap->offbitmap, off, len);
+}
+
+static inline int xoff_bitmap_walk(struct xoff_bitmap *bitmap,
+		xbitmap64_walk_fn fn, void *priv)
+{
+	return xbitmap64_walk(&bitmap->offbitmap, fn, priv);
+}
+
+#endif	/* __XFS_SCRUB_OFF_BITMAP_H__ */