bcachefs: Kill bkey_type_successor

Previously, BTREE_ID_INODES was special - inodes were indexed by the
inode field, which meant the offset field of struct bpos wasn't used,
which led to special cases in e.g. the btree iterator code.

Now, inodes in the inodes btree are indexed by the offset field.

Also: prevously min_key was special for extents btrees, min_key for
extents would equal max_key for the previous node. Now, min_key =
bkey_successor() of the previous node, same as non extent btrees.

This means we can completely get rid of
btree_type_sucessor/predecessor.

Also make some improvements to the metadata IO validate/compat code.

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

1 files changed, 47 insertions, 0 deletions

diff --git a/fs/bcachefs/btree_io.h b/fs/bcachefs/btree_io.h
index a02e261c2eb2..fa996fdc5474 100644
--- a/fs/bcachefs/btree_io.h
+++ b/fs/bcachefs/btree_io.h
@@ -2,6 +2,7 @@
 #ifndef _BCACHEFS_BTREE_IO_H
 #define _BCACHEFS_BTREE_IO_H
 
+#include "bkey_methods.h"
 #include "bset.h"
 #include "btree_locking.h"
 #include "extents.h"
@@ -140,4 +141,50 @@ void bch2_btree_flush_all_writes(struct bch_fs *);
 void bch2_btree_verify_flushed(struct bch_fs *);
 ssize_t bch2_dirty_btree_nodes_print(struct bch_fs *, char *);
 
+static inline void compat_bformat(unsigned level, enum btree_id btree_id,
+				 unsigned version, unsigned big_endian,
+				 int write, struct bkey_format *f)
+{
+	if (version < bcachefs_metadata_version_inode_btree_change &&
+	    btree_id == BTREE_ID_INODES) {
+		swap(f->bits_per_field[BKEY_FIELD_INODE],
+		     f->bits_per_field[BKEY_FIELD_OFFSET]);
+		swap(f->field_offset[BKEY_FIELD_INODE],
+		     f->field_offset[BKEY_FIELD_OFFSET]);
+	}
+}
+
+static inline void compat_bpos(unsigned level, enum btree_id btree_id,
+			       unsigned version, unsigned big_endian,
+			       int write, struct bpos *p)
+{
+	if (big_endian != CPU_BIG_ENDIAN)
+		bch2_bpos_swab(p);
+
+	if (version < bcachefs_metadata_version_inode_btree_change &&
+	    btree_id == BTREE_ID_INODES)
+		swap(p->inode, p->offset);
+}
+
+static inline void compat_btree_node(unsigned level, enum btree_id btree_id,
+				     unsigned version, unsigned big_endian,
+				     int write,
+				     struct btree_node *bn)
+{
+	if (version < bcachefs_metadata_version_inode_btree_change &&
+	    btree_node_type_is_extents(btree_id) &&
+	    bkey_cmp(bn->min_key, POS_MIN) &&
+	    write)
+		bn->min_key = bkey_predecessor(bn->min_key);
+
+	compat_bpos(level, btree_id, version, big_endian, write, &bn->min_key);
+	compat_bpos(level, btree_id, version, big_endian, write, &bn->max_key);
+
+	if (version < bcachefs_metadata_version_inode_btree_change &&
+	    btree_node_type_is_extents(btree_id) &&
+	    bkey_cmp(bn->min_key, POS_MIN) &&
+	    !write)
+		bn->min_key = bkey_successor(bn->min_key);
+}
+
 #endif /* _BCACHEFS_BTREE_IO_H */