bcachefs: Rip out code for storing backpointers in alloc keys

We don't store backpointers in alloc keys anymore, since we gained the
btree write buffer.

This patch drops support for backpointers in alloc keys, and revs the on
disk format version so that we know a fsck is required.

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

1 files changed, 14 insertions, 20 deletions

diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index e5cbb4bce1ee..06032556d5c4 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -451,6 +451,8 @@ void __bch2_alloc_to_v4(struct bkey_s_c k, struct bch_alloc_v4 *out)
 
 		if (src < dst)
 			memset(src, 0, dst - src);
+
+		SET_BCH_ALLOC_V4_NR_BACKPOINTERS(out, 0);
 	} else {
 		struct bkey_alloc_unpacked u = bch2_alloc_unpack(k);
 
@@ -476,38 +478,26 @@ static noinline struct bkey_i_alloc_v4 *
 __bch2_alloc_to_v4_mut(struct btree_trans *trans, struct bkey_s_c k)
 {
 	struct bkey_i_alloc_v4 *ret;
+
+	ret = bch2_trans_kmalloc(trans, sizeof(struct bkey_i_alloc_v4));
+	if (IS_ERR(ret))
+		return ret;
+
 	if (k.k->type == KEY_TYPE_alloc_v4) {
-		struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(k);
-		unsigned bytes = sizeof(struct bkey_i_alloc_v4) +
-			BCH_ALLOC_V4_NR_BACKPOINTERS(a.v) *
-			sizeof(struct bch_backpointer);
 		void *src, *dst;
 
-		/*
-		 * Reserve space for one more backpointer here:
-		 * Not sketchy at doing it this way, nope...
-		 */
-		ret = bch2_trans_kmalloc(trans, bytes + sizeof(struct bch_backpointer));
-		if (IS_ERR(ret))
-			return ret;
-
 		bkey_reassemble(&ret->k_i, k);
 
 		src = alloc_v4_backpointers(&ret->v);
 		SET_BCH_ALLOC_V4_BACKPOINTERS_START(&ret->v, BCH_ALLOC_V4_U64s);
 		dst = alloc_v4_backpointers(&ret->v);
 
-		memmove(dst, src, BCH_ALLOC_V4_NR_BACKPOINTERS(&ret->v) *
-			sizeof(struct bch_backpointer));
 		if (src < dst)
 			memset(src, 0, dst - src);
+
+		SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&ret->v, 0);
 		set_alloc_v4_u64s(ret);
 	} else {
-		ret = bch2_trans_kmalloc(trans, sizeof(struct bkey_i_alloc_v4) +
-					 sizeof(struct bch_backpointer));
-		if (IS_ERR(ret))
-			return ret;
-
 		bkey_alloc_v4_init(&ret->k_i);
 		ret->k.p = k.k->p;
 		bch2_alloc_to_v4(k, &ret->v);
@@ -517,8 +507,12 @@ __bch2_alloc_to_v4_mut(struct btree_trans *trans, struct bkey_s_c k)
 
 static inline struct bkey_i_alloc_v4 *bch2_alloc_to_v4_mut_inlined(struct btree_trans *trans, struct bkey_s_c k)
 {
+	struct bkey_s_c_alloc_v4 a;
+
 	if (likely(k.k->type == KEY_TYPE_alloc_v4) &&
-	    BCH_ALLOC_V4_BACKPOINTERS_START(bkey_s_c_to_alloc_v4(k).v) == BCH_ALLOC_V4_U64s) {
+	    ((a = bkey_s_c_to_alloc_v4(k), true) &&
+	     BCH_ALLOC_V4_BACKPOINTERS_START(a.v) == BCH_ALLOC_V4_U64s &&
+	     BCH_ALLOC_V4_NR_BACKPOINTERS(a.v) == 0)) {
 		/*
 		 * Reserve space for one more backpointer here:
 		 * Not sketchy at doing it this way, nope...