bcache: Add bch_bkey_equal_header()

Checks if two keys have equivalent header fields.
(good enough for replacement or merging)

Used in bch_bkey_try_merge, and replacing a key
in the btree.
Signed-off-by: Nicholas Swenson <nks@daterainc.com>
Signed-off-by: Kent Overstreet <kmo@daterainc.com>

drivers/md/bcache/bset.c

@@ -788,12 +788,8 @@ bool bch_bkey_try_merge(struct btree_keys *b, struct bkey *l, struct bkey *r)
 	 * Assumes left and right are in order
 	 * Left and right must be exactly aligned
 	 */
-	if (KEY_U64s(l) != KEY_U64s(r) ||
-	    KEY_DELETED(l) != KEY_DELETED(r) ||
-	    KEY_CACHED(l) != KEY_CACHED(r) ||
-	    KEY_VERSION(l) != KEY_VERSION(r) ||
-	    KEY_CSUM(l) != KEY_CSUM(r) ||
-	    bkey_cmp(l, &START_KEY(r)))
+	if (!bch_bkey_equal_header(l, r) ||
+	     bkey_cmp(l, &START_KEY(r)))
 		return false;
 
 	return b->ops->key_merge(b, l, r);

drivers/md/bcache/bset.h

@@ -448,6 +448,14 @@ static inline void bch_bkey_to_text(struct btree_keys *b, char *buf,
 	return b->ops->key_to_text(buf, size, k);
 }
 
+static inline bool bch_bkey_equal_header(const struct bkey *l,
+					 const struct bkey *r)
+{
+	return (KEY_DIRTY(l) == KEY_DIRTY(r) &&
+		KEY_PTRS(l) == KEY_PTRS(r) &&
+		KEY_CSUM(l) == KEY_CSUM(l));
+}
+
 /* Keylists */
 
 struct keylist {

drivers/md/bcache/extents.c

@@ -372,8 +372,7 @@ static bool bch_extent_insert_fixup(struct btree_keys *b,
 			if (KEY_START(k) > KEY_START(insert) + sectors_found)
 				goto check_failed;
 
-			if (KEY_PTRS(k) != KEY_PTRS(replace_key) ||
-			    KEY_DIRTY(k) != KEY_DIRTY(replace_key))
+			if (!bch_bkey_equal_header(k, replace_key))
 				goto check_failed;
 
 			/* skip past gen */