[XFS] add helpers for addressing entities inside a btree block
Add new helpers in xfs_btree.c to find the record, key and block pointer
entries inside a btree block. To implement this genericly the
->get_maxrecs methods and two new xfs_btree_ops entries for the key and
record sizes are used. Also add a big comment describing how the
addressing inside a btree block works.
Note that these helpers are unused until users are introduced in the next
patches and this patch will thus cause some harmless compiler warnings.
SGI-PV: 985583
SGI-Modid: xfs-linux-melb:xfs-kern:32189a
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Bill O'Donnell <billodo@sgi.com>
Signed-off-by: David Chinner <david@fromorbit.com>
diff --git a/fs/xfs/xfs_btree.h b/fs/xfs/xfs_btree.h
index 5398cd0..593f82b 100644
--- a/fs/xfs/xfs_btree.h
+++ b/fs/xfs/xfs_btree.h
@@ -180,6 +180,10 @@
#define XFS_BTREE_MAXLEVELS 8 /* max of all btrees */
struct xfs_btree_ops {
+ /* size of the key and record structures */
+ size_t key_len;
+ size_t rec_len;
+
/* cursor operations */
struct xfs_btree_cur *(*dup_cursor)(struct xfs_btree_cur *);
@@ -497,6 +501,15 @@
int lev, /* level in btree */
struct xfs_buf *bp); /* new buffer to set */
+
+/*
+ * Helpers.
+ */
+static inline int xfs_btree_get_level(struct xfs_btree_block *block)
+{
+ return be16_to_cpu(block->bb_level);
+}
+
#endif /* __KERNEL__ */