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, 67 insertions, 262 deletions

diff --git a/fs/bcachefs/backpointers.c b/fs/bcachefs/backpointers.c
index 9121fae0fd6c..a3a1ed6e5968 100644
--- a/fs/bcachefs/backpointers.c
+++ b/fs/bcachefs/backpointers.c
@@ -69,6 +69,10 @@ void bch2_backpointer_to_text(struct printbuf *out, const struct bch_backpointer
 
 void bch2_backpointer_k_to_text(struct printbuf *out, struct bch_fs *c, struct bkey_s_c k)
 {
+	prt_str(out, "bucket=");
+	bch2_bpos_to_text(out, bp_pos_to_bucket(c, k.k->p));
+	prt_str(out, " ");
+
 	bch2_backpointer_to_text(out, bkey_s_c_to_backpointer(k).v);
 }
 
@@ -81,117 +85,6 @@ void bch2_backpointer_swab(struct bkey_s k)
 	bch2_bpos_swab(&bp.v->pos);
 }
 
-#define BACKPOINTER_OFFSET_MAX	((1ULL << 40) - 1)
-
-static inline int backpointer_cmp(struct bch_backpointer l, struct bch_backpointer r)
-{
-	return cmp_int(l.bucket_offset, r.bucket_offset);
-}
-
-static int bch2_backpointer_del_by_offset(struct btree_trans *trans,
-					  struct bpos bucket,
-					  u64 bp_offset,
-					  struct bch_backpointer bp)
-{
-	struct bch_fs *c = trans->c;
-	struct btree_iter iter;
-	struct bkey_s_c k;
-	int ret;
-
-	if (bp_offset < BACKPOINTER_OFFSET_MAX) {
-		struct bch_backpointer *bps;
-		struct bkey_i_alloc_v4 *a;
-		unsigned i, nr;
-
-		bch2_trans_iter_init(trans, &iter, BTREE_ID_alloc,
-				     bucket,
-				     BTREE_ITER_INTENT|
-				     BTREE_ITER_SLOTS|
-				     BTREE_ITER_WITH_UPDATES);
-		k = bch2_btree_iter_peek_slot(&iter);
-		ret = bkey_err(k);
-		if (ret)
-			goto err;
-
-		if (k.k->type != KEY_TYPE_alloc_v4) {
-			ret = -ENOENT;
-			goto err;
-		}
-
-		a = bch2_alloc_to_v4_mut(trans, k);
-		ret = PTR_ERR_OR_ZERO(a);
-		if (ret)
-			goto err;
-		bps = alloc_v4_backpointers(&a->v);
-		nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
-
-		for (i = 0; i < nr; i++) {
-			if (bps[i].bucket_offset == bp_offset)
-				goto found;
-			if (bps[i].bucket_offset > bp_offset)
-				break;
-		}
-
-		ret = -ENOENT;
-		goto err;
-found:
-		if (memcmp(&bps[i], &bp, sizeof(bp))) {
-			ret = -ENOENT;
-			goto err;
-		}
-		array_remove_item(bps, nr, i);
-		SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
-		set_alloc_v4_u64s(a);
-		ret = bch2_trans_update(trans, &iter, &a->k_i, 0);
-	} else {
-		bp_offset -= BACKPOINTER_OFFSET_MAX;
-
-		bch2_trans_iter_init(trans, &iter, BTREE_ID_backpointers,
-				     bucket_pos_to_bp(c, bucket, bp_offset),
-				     BTREE_ITER_INTENT|
-				     BTREE_ITER_SLOTS|
-				     BTREE_ITER_WITH_UPDATES);
-		k = bch2_btree_iter_peek_slot(&iter);
-		ret = bkey_err(k);
-		if (ret)
-			goto err;
-
-		if (k.k->type != KEY_TYPE_backpointer ||
-		    memcmp(bkey_s_c_to_backpointer(k).v, &bp, sizeof(bp))) {
-			ret = -ENOENT;
-			goto err;
-		}
-
-		ret = bch2_btree_delete_at(trans, &iter, 0);
-	}
-err:
-	bch2_trans_iter_exit(trans, &iter);
-	return ret;
-}
-
-bool bch2_bucket_backpointer_del(struct btree_trans *trans,
-				 struct bkey_i_alloc_v4 *a,
-				 struct bch_backpointer bp)
-{
-	struct bch_backpointer *bps = alloc_v4_backpointers(&a->v);
-	unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v);
-
-	for (i = 0; i < nr; i++) {
-		int cmp = backpointer_cmp(bps[i], bp) ?:
-			memcmp(&bps[i], &bp, sizeof(bp));
-		if (!cmp) {
-			array_remove_item(bps, nr, i);
-			SET_BCH_ALLOC_V4_NR_BACKPOINTERS(&a->v, nr);
-			set_alloc_v4_u64s(a);
-			return true;
-		}
-		if (cmp >= 0)
-			break;
-	}
-
-	return false;
-}
-
 static noinline int backpointer_mod_err(struct btree_trans *trans,
 					struct bch_backpointer bp,
 					struct bkey_s_c bp_k,
@@ -245,7 +138,7 @@ static noinline int backpointer_mod_err(struct btree_trans *trans,
 }
 
 int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
-				struct bkey_i_alloc_v4 *a,
+				struct bpos bucket,
 				struct bch_backpointer bp,
 				struct bkey_s_c orig_k,
 				bool insert)
@@ -262,7 +155,7 @@ int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
 		return ret;
 
 	bkey_backpointer_init(&bp_k->k_i);
-	bp_k->k.p = bucket_pos_to_bp(c, a->k.p, bp.bucket_offset);
+	bp_k->k.p = bucket_pos_to_bp(c, bucket, bp.bucket_offset);
 	bp_k->v = bp;
 
 	if (!insert) {
@@ -271,7 +164,7 @@ int bch2_bucket_backpointer_mod_nowritebuffer(struct btree_trans *trans,
 	}
 
 	bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
-			     bucket_pos_to_bp(c, a->k.p, bp.bucket_offset),
+			     bp_k->k.p,
 			     BTREE_ITER_INTENT|
 			     BTREE_ITER_SLOTS|
 			     BTREE_ITER_WITH_UPDATES);
@@ -298,94 +191,62 @@ err:
 /*
  * Find the next backpointer >= *bp_offset:
  */
-int __bch2_get_next_backpointer(struct btree_trans *trans,
-				struct bpos bucket, int gen,
-				u64 *bp_offset,
-				struct bpos *bp_pos_ret,
-				struct bch_backpointer *dst,
-				unsigned iter_flags)
+int bch2_get_next_backpointer(struct btree_trans *trans,
+			      struct bpos bucket, int gen,
+			      struct bpos *bp_pos,
+			      struct bch_backpointer *bp,
+			      unsigned iter_flags)
 {
 	struct bch_fs *c = trans->c;
-	struct bpos bp_pos, bp_end_pos;
-	struct btree_iter alloc_iter, bp_iter = { NULL };
+	struct bpos bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
+	struct btree_iter alloc_iter = { NULL }, bp_iter = { NULL };
 	struct bkey_s_c k;
-	struct bkey_s_c_alloc_v4 a;
-	size_t i;
-	int ret;
-
-	if (*bp_offset == U64_MAX)
-		return 0;
-
-	bp_pos = bucket_pos_to_bp(c, bucket,
-				  max(*bp_offset, BACKPOINTER_OFFSET_MAX) - BACKPOINTER_OFFSET_MAX);
-	bp_end_pos = bucket_pos_to_bp(c, bpos_nosnap_successor(bucket), 0);
-
-	bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
-			     bucket, BTREE_ITER_CACHED);
-	k = bch2_btree_iter_peek_slot(&alloc_iter);
-	ret = bkey_err(k);
-	if (ret)
-		goto out;
-
-	if (k.k->type != KEY_TYPE_alloc_v4)
-		goto done;
+	int ret = 0;
 
-	a = bkey_s_c_to_alloc_v4(k);
-	if (gen >= 0 && a.v->gen != gen)
+	if (bpos_ge(*bp_pos, bp_end_pos))
 		goto done;
 
-	for (i = 0; i < BCH_ALLOC_V4_NR_BACKPOINTERS(a.v); i++) {
-		if (alloc_v4_backpointers_c(a.v)[i].bucket_offset < *bp_offset)
-			continue;
+	if (gen >= 0) {
+		bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc,
+				     bucket, BTREE_ITER_CACHED|iter_flags);
+		k = bch2_btree_iter_peek_slot(&alloc_iter);
+		ret = bkey_err(k);
+		if (ret)
+			goto out;
 
-		*dst = alloc_v4_backpointers_c(a.v)[i];
-		*bp_offset = dst->bucket_offset;
-		goto out;
+		if (k.k->type != KEY_TYPE_alloc_v4 ||
+		    bkey_s_c_to_alloc_v4(k).v->gen != gen)
+			goto done;
 	}
 
+	*bp_pos = bpos_max(*bp_pos, bucket_pos_to_bp(c, bucket, 0));
+
 	for_each_btree_key_norestart(trans, bp_iter, BTREE_ID_backpointers,
-				     bp_pos, 0, k, ret) {
+				     *bp_pos, iter_flags, k, ret) {
 		if (bpos_ge(k.k->p, bp_end_pos))
 			break;
 
-		if (k.k->type != KEY_TYPE_backpointer)
-			continue;
-
-		*dst = *bkey_s_c_to_backpointer(k).v;
-		*bp_offset = dst->bucket_offset + BACKPOINTER_OFFSET_MAX;
-		*bp_pos_ret = k.k->p;
+		*bp_pos = k.k->p;
+		*bp = *bkey_s_c_to_backpointer(k).v;
 		goto out;
 	}
 done:
-	*bp_offset = U64_MAX;
+	*bp_pos = SPOS_MAX;
 out:
 	bch2_trans_iter_exit(trans, &bp_iter);
 	bch2_trans_iter_exit(trans, &alloc_iter);
 	return ret;
 }
 
-int bch2_get_next_backpointer(struct btree_trans *trans,
-			      struct bpos bucket, int gen,
-			      u64 *bp_offset,
-			      struct bch_backpointer *dst,
-			      unsigned iter_flags)
-{
-	struct bpos bp_pos;
-
-	return __bch2_get_next_backpointer(trans, bucket, gen,
-					   bp_offset, &bp_pos,
-					   dst, iter_flags);
-}
-
 static void backpointer_not_found(struct btree_trans *trans,
-				  struct bpos bucket,
-				  u64 bp_offset,
+				  struct bpos bp_pos,
 				  struct bch_backpointer bp,
 				  struct bkey_s_c k,
 				  const char *thing_it_points_to)
 {
 	struct bch_fs *c = trans->c;
 	struct printbuf buf = PRINTBUF;
+	struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 
 	if (likely(!bch2_backpointers_no_use_write_buffer))
 		return;
@@ -396,14 +257,9 @@ static void backpointer_not_found(struct btree_trans *trans,
 	bch2_bpos_to_text(&buf, bucket);
 	prt_printf(&buf, "\n  ");
 
-	if (bp_offset >= BACKPOINTER_OFFSET_MAX) {
-		struct bpos bp_pos =
-			bucket_pos_to_bp(c, bucket,
-					bp_offset - BACKPOINTER_OFFSET_MAX);
-		prt_printf(&buf, "backpointer pos: ");
-		bch2_bpos_to_text(&buf, bp_pos);
-		prt_printf(&buf, "\n  ");
-	}
+	prt_printf(&buf, "backpointer pos: ");
+	bch2_bpos_to_text(&buf, bp_pos);
+	prt_printf(&buf, "\n  ");
 
 	bch2_backpointer_to_text(&buf, &bp);
 	prt_printf(&buf, "\n  ");
@@ -418,12 +274,12 @@ static void backpointer_not_found(struct btree_trans *trans,
 
 struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 					 struct btree_iter *iter,
-					 struct bpos bucket,
-					 u64 bp_offset,
+					 struct bpos bp_pos,
 					 struct bch_backpointer bp,
 					 unsigned iter_flags)
 {
 	struct bch_fs *c = trans->c;
+	struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 	struct bkey_s_c k;
 
 	bch2_trans_node_iter_init(trans, iter,
@@ -456,7 +312,7 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 			 * been written out yet - backpointer_get_node() checks for
 			 * this:
 			 */
-			b = bch2_backpointer_get_node(trans, iter, bucket, bp_offset, bp);
+			b = bch2_backpointer_get_node(trans, iter, bp_pos, bp);
 			if (!IS_ERR_OR_NULL(b))
 				return bkey_i_to_s_c(&b->key);
 
@@ -467,7 +323,7 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 			return bkey_s_c_null;
 		}
 
-		backpointer_not_found(trans, bucket, bp_offset, bp, k, "extent");
+		backpointer_not_found(trans, bp_pos, bp, k, "extent");
 	}
 
 	return bkey_s_c_null;
@@ -475,11 +331,11 @@ struct bkey_s_c bch2_backpointer_get_key(struct btree_trans *trans,
 
 struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 					struct btree_iter *iter,
-					struct bpos bucket,
-					u64 bp_offset,
+					struct bpos bp_pos,
 					struct bch_backpointer bp)
 {
 	struct bch_fs *c = trans->c;
+	struct bpos bucket = bp_pos_to_bucket(c, bp_pos);
 	struct btree *b;
 
 	BUG_ON(!bp.level);
@@ -502,7 +358,7 @@ struct btree *bch2_backpointer_get_node(struct btree_trans *trans,
 	if (b && btree_node_will_make_reachable(b)) {
 		b = ERR_PTR(-BCH_ERR_backpointer_to_overwritten_btree_node);
 	} else {
-		backpointer_not_found(trans, bucket, bp_offset, bp,
+		backpointer_not_found(trans, bp_pos, bp,
 				      bkey_i_to_s_c(&b->key), "btree node");
 		b = NULL;
 	}
@@ -571,7 +427,7 @@ struct bpos_level {
 };
 
 static int check_bp_exists(struct btree_trans *trans,
-			   struct bpos bucket_pos,
+			   struct bpos bucket,
 			   struct bch_backpointer bp,
 			   struct bkey_s_c orig_k,
 			   struct bpos bucket_start,
@@ -579,40 +435,20 @@ static int check_bp_exists(struct btree_trans *trans,
 			   struct bpos_level *last_flushed)
 {
 	struct bch_fs *c = trans->c;
-	struct btree_iter alloc_iter, bp_iter = { NULL };
+	struct btree_iter bp_iter = { NULL };
 	struct printbuf buf = PRINTBUF;
-	struct bkey_s_c alloc_k, bp_k;
+	struct bkey_s_c bp_k;
 	int ret;
 
-	if (bpos_lt(bucket_pos, bucket_start) ||
-	    bpos_gt(bucket_pos, bucket_end))
+	if (bpos_lt(bucket, bucket_start) ||
+	    bpos_gt(bucket, bucket_end))
 		return 0;
 
-	bch2_trans_iter_init(trans, &alloc_iter, BTREE_ID_alloc, bucket_pos, 0);
-	alloc_k = bch2_btree_iter_peek_slot(&alloc_iter);
-	ret = bkey_err(alloc_k);
-	if (ret)
-		goto err;
-
-	if (alloc_k.k->type == KEY_TYPE_alloc_v4) {
-		struct bkey_s_c_alloc_v4 a = bkey_s_c_to_alloc_v4(alloc_k);
-		const struct bch_backpointer *bps = alloc_v4_backpointers_c(a.v);
-		unsigned i, nr = BCH_ALLOC_V4_NR_BACKPOINTERS(a.v);
-
-		for (i = 0; i < nr; i++) {
-			int cmp = backpointer_cmp(bps[i], bp) ?:
-				memcmp(&bps[i], &bp, sizeof(bp));
-			if (!cmp)
-				goto out;
-			if (cmp >= 0)
-				break;
-		}
-	} else {
+	if (!bch2_dev_bucket_exists(c, bucket))
 		goto missing;
-	}
 
 	bch2_trans_iter_init(trans, &bp_iter, BTREE_ID_backpointers,
-			     bucket_pos_to_bp(c, bucket_pos, bp.bucket_offset),
+			     bucket_pos_to_bp(c, bucket, bp.bucket_offset),
 			     0);
 	bp_k = bch2_btree_iter_peek_slot(&bp_iter);
 	ret = bkey_err(bp_k);
@@ -636,11 +472,9 @@ out:
 err:
 fsck_err:
 	bch2_trans_iter_exit(trans, &bp_iter);
-	bch2_trans_iter_exit(trans, &alloc_iter);
 	printbuf_exit(&buf);
 	return ret;
 missing:
-
 	prt_printf(&buf, "missing backpointer for btree=%s l=%u ",
 	       bch2_btree_ids[bp.btree_id], bp.level);
 	bch2_bkey_val_to_text(&buf, c, orig_k);
@@ -649,12 +483,8 @@ missing:
 
 	if (c->sb.version < bcachefs_metadata_version_backpointers ||
 	    c->opts.reconstruct_alloc ||
-	    fsck_err(c, "%s", buf.buf)) {
-		struct bkey_i_alloc_v4 *a = bch2_alloc_to_v4_mut(trans, alloc_k);
-
-		ret   = PTR_ERR_OR_ZERO(a) ?:
-			bch2_bucket_backpointer_mod(trans, a, bp, orig_k, true);
-	}
+	    fsck_err(c, "%s", buf.buf))
+		ret = bch2_bucket_backpointer_mod(trans, bucket, bp, orig_k, true);
 
 	goto out;
 }
@@ -953,53 +783,40 @@ int bch2_check_extents_to_backpointers(struct bch_fs *c)
 }
 
 static int check_one_backpointer(struct btree_trans *trans,
-				 struct bpos bucket,
-				 u64 *bp_offset,
 				 struct bbpos start,
 				 struct bbpos end,
+				 struct bkey_s_c_backpointer bp,
 				 struct bpos *last_flushed_pos)
 {
 	struct bch_fs *c = trans->c;
 	struct btree_iter iter;
-	struct bch_backpointer bp;
-	struct bbpos pos;
-	struct bpos bp_pos;
+	struct bbpos pos = bp_to_bbpos(*bp.v);
 	struct bkey_s_c k;
 	struct printbuf buf = PRINTBUF;
 	int ret;
 
-	ret = __bch2_get_next_backpointer(trans, bucket, -1, bp_offset, &bp_pos, &bp, 0);
-	if (ret || *bp_offset == U64_MAX)
-		return ret;
-
-	pos = bp_to_bbpos(bp);
 	if (bbpos_cmp(pos, start) < 0 ||
 	    bbpos_cmp(pos, end) > 0)
 		return 0;
 
-	k = bch2_backpointer_get_key(trans, &iter, bucket, *bp_offset, bp, 0);
+	k = bch2_backpointer_get_key(trans, &iter, bp.k->p, *bp.v, 0);
 	ret = bkey_err(k);
 	if (ret == -BCH_ERR_backpointer_to_overwritten_btree_node)
 		return 0;
 	if (ret)
 		return ret;
 
-	if (!k.k && !bpos_eq(*last_flushed_pos, bp_pos)) {
-		*last_flushed_pos = bp_pos;
+	if (!k.k && !bpos_eq(*last_flushed_pos, bp.k->p)) {
+		*last_flushed_pos = bp.k->p;
 		ret = bch2_btree_write_buffer_flush_sync(trans) ?:
 			-BCH_ERR_transaction_restart_write_buffer_flush;
 		goto out;
 	}
 
 	if (fsck_err_on(!k.k, c,
-			"backpointer for %llu:%llu:%llu (btree pos %llu:%llu) points to missing extent\n  %s",
-			bucket.inode, bucket.offset, (u64) bp.bucket_offset,
-			bp_pos.inode, bp_pos.offset,
-			(bch2_backpointer_to_text(&buf, &bp), buf.buf))) {
-		ret = bch2_backpointer_del_by_offset(trans, bucket, *bp_offset, bp);
-		if (ret == -ENOENT)
-			bch_err(c, "backpointer at %llu not found", *bp_offset);
-	}
+			"backpointer for missing extent\n  %s",
+			(bch2_backpointer_k_to_text(&buf, c, bp.s_c), buf.buf)))
+		return bch2_btree_delete_at_buffered(trans, BTREE_ID_backpointers, bp.k->p);
 out:
 fsck_err:
 	bch2_trans_iter_exit(trans, &iter);
@@ -1014,25 +831,13 @@ static int bch2_check_backpointers_to_extents_pass(struct btree_trans *trans,
 	struct btree_iter iter;
 	struct bkey_s_c k;
 	struct bpos last_flushed_pos = SPOS_MAX;
-	int ret = 0;
 
-	for_each_btree_key(trans, iter, BTREE_ID_alloc, POS_MIN,
-			   BTREE_ITER_PREFETCH, k, ret) {
-		u64 bp_offset = 0;
-
-		while (!(ret = commit_do(trans, NULL, NULL,
-					 BTREE_INSERT_LAZY_RW|
-					 BTREE_INSERT_NOFAIL,
-				check_one_backpointer(trans, iter.pos, &bp_offset,
-						      start, end, &last_flushed_pos))) &&
-		       bp_offset < U64_MAX)
-			bp_offset++;
-
-		if (ret)
-			break;
-	}
-	bch2_trans_iter_exit(trans, &iter);
-	return ret < 0 ? ret : 0;
+	return for_each_btree_key_commit(trans, iter, BTREE_ID_backpointers,
+				  POS_MIN, BTREE_ITER_PREFETCH, k,
+				  NULL, NULL, BTREE_INSERT_LAZY_RW|BTREE_INSERT_NOFAIL,
+		check_one_backpointer(trans, start, end,
+				      bkey_s_c_to_backpointer(k),
+				      &last_flushed_pos));
 }
 
 int bch2_check_backpointers_to_extents(struct bch_fs *c)