xfs: support in-memory btrees

Adapt the generic btree cursor code to be able to create a btree whose
buffers come from a (presumably in-memory) buftarg with a header block
that's specific to in-memory btrees.  We'll connect this to other parts
of online scrub in the next patches.

Note that in-memory btrees always have a block size matching the system
memory page size for efficiency reasons.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

1 files changed, 87 insertions, 0 deletions

diff --git a/fs/xfs/libxfs/xfs_btree_mem.h b/fs/xfs/libxfs/xfs_btree_mem.h
new file mode 100644
index 000000000000..6ca9ea64a9a4
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_btree_mem.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 Oracle.  All Rights Reserved.
+ * Author: Darrick J. Wong <djwong@kernel.org>
+ */
+#ifndef __XFS_BTREE_MEM_H__
+#define __XFS_BTREE_MEM_H__
+
+struct xfbtree;
+
+#ifdef CONFIG_XFS_IN_MEMORY_BTREE
+unsigned int xfs_btree_mem_head_nlevels(struct xfs_buf *head_bp);
+
+struct xfs_buftarg *xfbtree_target(struct xfbtree *xfbtree);
+int xfbtree_check_ptr(struct xfs_btree_cur *cur,
+		const union xfs_btree_ptr *ptr, int index, int level);
+xfs_daddr_t xfbtree_ptr_to_daddr(struct xfs_btree_cur *cur,
+		const union xfs_btree_ptr *ptr);
+void xfbtree_buf_to_ptr(struct xfs_btree_cur *cur, struct xfs_buf *bp,
+		union xfs_btree_ptr *ptr);
+
+unsigned int xfbtree_bbsize(void);
+
+void xfbtree_set_root(struct xfs_btree_cur *cur,
+		const union xfs_btree_ptr *ptr, int inc);
+void xfbtree_init_ptr_from_cur(struct xfs_btree_cur *cur,
+		union xfs_btree_ptr *ptr);
+struct xfs_btree_cur *xfbtree_dup_cursor(struct xfs_btree_cur *cur);
+bool xfbtree_verify_xfileoff(struct xfs_btree_cur *cur,
+		unsigned long long xfoff);
+xfs_failaddr_t xfbtree_check_block_owner(struct xfs_btree_cur *cur,
+		struct xfs_btree_block *block);
+unsigned long long xfbtree_owner(struct xfs_btree_cur *cur);
+xfs_failaddr_t xfbtree_lblock_verify(struct xfs_buf *bp, unsigned int max_recs);
+xfs_failaddr_t xfbtree_sblock_verify(struct xfs_buf *bp, unsigned int max_recs);
+unsigned long long xfbtree_buf_to_xfoff(struct xfs_btree_cur *cur,
+		struct xfs_buf *bp);
+#else
+static inline unsigned int xfs_btree_mem_head_nlevels(struct xfs_buf *head_bp)
+{
+	return 0;
+}
+
+static inline struct xfs_buftarg *
+xfbtree_target(struct xfbtree *xfbtree)
+{
+	return NULL;
+}
+
+static inline int
+xfbtree_check_ptr(struct xfs_btree_cur *cur, const union xfs_btree_ptr *ptr,
+		  int index, int level)
+{
+	return 0;
+}
+
+static inline xfs_daddr_t
+xfbtree_ptr_to_daddr(struct xfs_btree_cur *cur, const union xfs_btree_ptr *ptr)
+{
+	return 0;
+}
+
+static inline void
+xfbtree_buf_to_ptr(
+	struct xfs_btree_cur	*cur,
+	struct xfs_buf		*bp,
+	union xfs_btree_ptr	*ptr)
+{
+	memset(ptr, 0xFF, sizeof(*ptr));
+}
+
+static inline unsigned int xfbtree_bbsize(void)
+{
+	return 0;
+}
+
+#define xfbtree_set_root			NULL
+#define xfbtree_init_ptr_from_cur		NULL
+#define xfbtree_dup_cursor			NULL
+#define xfbtree_verify_xfileoff(cur, xfoff)	(false)
+#define xfbtree_check_block_owner(cur, block)	NULL
+#define xfbtree_owner(cur)			(0ULL)
+#define xfbtree_buf_to_xfoff(cur, bp)		(-1)
+
+#endif /* CONFIG_XFS_IN_MEMORY_BTREE */
+
+#endif /* __XFS_BTREE_MEM_H__ */