bcachefs: bch2_disk_accounting_mod2()

We're hitting some issues with uninitialized struct padding, flagged by
kmsan.

They appear to be falso positives, otherwise bch2_accounting_validate()
would have flagged them as "junk at end". But for now, we'll need to
initialize disk_accounting_pos with memset().

This adds a new helper, bch2_disk_accounting_mod2(), that initializes a
disk_accounting_pos and does the accounting mod all at once - so overall
things actually get slightly more ergonomic.

BCH_DISK_ACCOUNTING_replicas keys are left for now; KMSAN isn't warning
about them and they're a bit special.

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

Author: Kent Overstreet

fs/bcachefs/alloc_background.c

@@ -777,14 +777,12 @@ static inline int bch2_dev_data_type_accounting_mod(struct btree_trans *trans, s
 						    s64 delta_sectors,
 						    s64 delta_fragmented, unsigned flags)
 {
-	struct disk_accounting_pos acc = {
-		.type = BCH_DISK_ACCOUNTING_dev_data_type,
-		.dev_data_type.dev		= ca->dev_idx,
-		.dev_data_type.data_type	= data_type,
-	};
 	s64 d[3] = { delta_buckets, delta_sectors, delta_fragmented };
 
-	return bch2_disk_accounting_mod(trans, &acc, d, 3, flags & BTREE_TRIGGER_gc);
+	return bch2_disk_accounting_mod2(trans, flags & BTREE_TRIGGER_gc,
+					 d, dev_data_type,
+					 .dev		= ca->dev_idx,
+					 .data_type	= data_type);
 }
 
 int bch2_alloc_key_to_dev_counters(struct btree_trans *trans, struct bch_dev *ca,

fs/bcachefs/buckets.c

@@ -724,9 +724,7 @@ static int __trigger_extent(struct btree_trans *trans,
 		.replicas.nr_required	= 1,
 	};
 
-	struct disk_accounting_pos acct_compression_key = {
-		.type			= BCH_DISK_ACCOUNTING_compression,
-	};
+	unsigned cur_compression_type = 0;
 	u64 compression_acct[3] = { 1, 0, 0 };
 
 	bkey_for_each_ptr_decode(k.k, ptrs, p, entry) {
@@ -760,13 +758,13 @@ static int __trigger_extent(struct btree_trans *trans,
 			acc_replicas_key.replicas.nr_required = 0;
 		}
 
-		if (acct_compression_key.compression.type &&
-		    acct_compression_key.compression.type != p.crc.compression_type) {
+		if (cur_compression_type &&
+		    cur_compression_type != p.crc.compression_type) {
 			if (flags & BTREE_TRIGGER_overwrite)
 				bch2_u64s_neg(compression_acct, ARRAY_SIZE(compression_acct));
 
-			ret = bch2_disk_accounting_mod(trans, &acct_compression_key, compression_acct,
-						       ARRAY_SIZE(compression_acct), gc);
+			ret = bch2_disk_accounting_mod2(trans, gc, compression_acct,
+							compression, cur_compression_type);
 			if (ret)
 				return ret;
 
@@ -775,7 +773,7 @@ static int __trigger_extent(struct btree_trans *trans,
 			compression_acct[2] = 0;
 		}
 
-		acct_compression_key.compression.type = p.crc.compression_type;
+		cur_compression_type = p.crc.compression_type;
 		if (p.crc.compression_type) {
 			compression_acct[1] += p.crc.uncompressed_size;
 			compression_acct[2] += p.crc.compressed_size;
@@ -789,45 +787,34 @@ static int __trigger_extent(struct btree_trans *trans,
 	}
 
 	if (acc_replicas_key.replicas.nr_devs && !level && k.k->p.snapshot) {
-		struct disk_accounting_pos acc_snapshot_key = {
-			.type			= BCH_DISK_ACCOUNTING_snapshot,
-			.snapshot.id		= k.k->p.snapshot,
-		};
-		ret = bch2_disk_accounting_mod(trans, &acc_snapshot_key, replicas_sectors, 1, gc);
+		ret = bch2_disk_accounting_mod2_nr(trans, gc, replicas_sectors, 1, snapshot, k.k->p.snapshot);
 		if (ret)
 			return ret;
 	}
 
-	if (acct_compression_key.compression.type) {
+	if (cur_compression_type) {
 		if (flags & BTREE_TRIGGER_overwrite)
 			bch2_u64s_neg(compression_acct, ARRAY_SIZE(compression_acct));
 
-		ret = bch2_disk_accounting_mod(trans, &acct_compression_key, compression_acct,
-					       ARRAY_SIZE(compression_acct), gc);
+		ret = bch2_disk_accounting_mod2(trans, gc, compression_acct,
+						compression, cur_compression_type);
 		if (ret)
 			return ret;
 	}
 
 	if (level) {
-		struct disk_accounting_pos acc_btree_key = {
-			.type		= BCH_DISK_ACCOUNTING_btree,
-			.btree.id	= btree_id,
-		};
-		ret = bch2_disk_accounting_mod(trans, &acc_btree_key, replicas_sectors, 1, gc);
+		ret = bch2_disk_accounting_mod2_nr(trans, gc, replicas_sectors, 1, btree, btree_id);
 		if (ret)
 			return ret;
 	} else {
 		bool insert = !(flags & BTREE_TRIGGER_overwrite);
-		struct disk_accounting_pos acc_inum_key = {
-			.type		= BCH_DISK_ACCOUNTING_inum,
-			.inum.inum	= k.k->p.inode,
-		};
+
 		s64 v[3] = {
 			insert ? 1 : -1,
 			insert ? k.k->size : -((s64) k.k->size),
 			*replicas_sectors,
 		};
-		ret = bch2_disk_accounting_mod(trans, &acc_inum_key, v, ARRAY_SIZE(v), gc);
+		ret = bch2_disk_accounting_mod2(trans, gc, v, inum, k.k->p.inode);
 		if (ret)
 			return ret;
 	}
@@ -876,15 +863,15 @@ int bch2_trigger_extent(struct btree_trans *trans,
 		}
 
 		int need_rebalance_delta = 0;
-		s64 need_rebalance_sectors_delta = 0;
+		s64 need_rebalance_sectors_delta[1] = { 0 };
 
 		s64 s = bch2_bkey_sectors_need_rebalance(c, old);
 		need_rebalance_delta -= s != 0;
-		need_rebalance_sectors_delta -= s;
+		need_rebalance_sectors_delta[0] -= s;
 
 		s = bch2_bkey_sectors_need_rebalance(c, new.s_c);
 		need_rebalance_delta += s != 0;
-		need_rebalance_sectors_delta += s;
+		need_rebalance_sectors_delta[0] += s;
 
 		if ((flags & BTREE_TRIGGER_transactional) && need_rebalance_delta) {
 			int ret = bch2_btree_bit_mod_buffered(trans, BTREE_ID_rebalance_work,
@@ -893,12 +880,9 @@ int bch2_trigger_extent(struct btree_trans *trans,
 				return ret;
 		}
 
-		if (need_rebalance_sectors_delta) {
-			struct disk_accounting_pos acc = {
-				.type		= BCH_DISK_ACCOUNTING_rebalance_work,
-			};
-			int ret = bch2_disk_accounting_mod(trans, &acc, &need_rebalance_sectors_delta, 1,
-							   flags & BTREE_TRIGGER_gc);
+		if (need_rebalance_sectors_delta[0]) {
+			int ret = bch2_disk_accounting_mod2(trans, flags & BTREE_TRIGGER_gc,
+							    need_rebalance_sectors_delta, rebalance_work);
 			if (ret)
 				return ret;
 		}
@@ -914,17 +898,13 @@ static int __trigger_reservation(struct btree_trans *trans,
 			enum btree_iter_update_trigger_flags flags)
 {
 	if (flags & (BTREE_TRIGGER_transactional|BTREE_TRIGGER_gc)) {
-		s64 sectors = k.k->size;
+		s64 sectors[1] = { k.k->size };
 
 		if (flags & BTREE_TRIGGER_overwrite)
-			sectors = -sectors;
-
-		struct disk_accounting_pos acc = {
-			.type = BCH_DISK_ACCOUNTING_persistent_reserved,
-			.persistent_reserved.nr_replicas = bkey_s_c_to_reservation(k).v->nr_replicas,
-		};
+			sectors[0] = -sectors[0];
 
-		return bch2_disk_accounting_mod(trans, &acc, &sectors, 1, flags & BTREE_TRIGGER_gc);
+		return bch2_disk_accounting_mod2(trans, flags & BTREE_TRIGGER_gc, sectors,
+				persistent_reserved, bkey_s_c_to_reservation(k).v->nr_replicas);
 	}
 
 	return 0;

fs/bcachefs/disk_accounting.h

@@ -85,6 +85,24 @@ static inline struct bpos disk_accounting_pos_to_bpos(struct disk_accounting_pos
 
 int bch2_disk_accounting_mod(struct btree_trans *, struct disk_accounting_pos *,
 			     s64 *, unsigned, bool);
+
+#define disk_accounting_key_init(_k, _type, ...)			\
+do {									\
+	memset(&(_k), 0, sizeof(_k));					\
+	(_k).type	= BCH_DISK_ACCOUNTING_##_type;			\
+	(_k)._type	= (struct bch_acct_##_type) { __VA_ARGS__ };	\
+} while (0)
+
+#define bch2_disk_accounting_mod2_nr(_trans, _gc, _v, _nr, ...)		\
+({									\
+	struct disk_accounting_pos pos;					\
+	disk_accounting_key_init(pos, __VA_ARGS__);			\
+	bch2_disk_accounting_mod(trans, &pos, _v, _nr, _gc);		\
+})
+
+#define bch2_disk_accounting_mod2(_trans, _gc, _v, ...)			\
+	bch2_disk_accounting_mod2_nr(_trans, _gc, _v, ARRAY_SIZE(_v), __VA_ARGS__)
+
 int bch2_mod_dev_cached_sectors(struct btree_trans *, unsigned, s64, bool);
 
 int bch2_accounting_validate(struct bch_fs *, struct bkey_s_c,

fs/bcachefs/disk_accounting_format.h

@@ -113,14 +113,14 @@ enum disk_accounting_type {
 	BCH_DISK_ACCOUNTING_TYPE_NR,
 };
 
-struct bch_nr_inodes {
+struct bch_acct_nr_inodes {
 };
 
-struct bch_persistent_reserved {
+struct bch_acct_persistent_reserved {
 	__u8			nr_replicas;
 };
 
-struct bch_dev_data_type {
+struct bch_acct_dev_data_type {
 	__u8			dev;
 	__u8			data_type;
 };
@@ -149,10 +149,10 @@ struct disk_accounting_pos {
 	struct {
 		__u8				type;
 		union {
-		struct bch_nr_inodes		nr_inodes;
-		struct bch_persistent_reserved	persistent_reserved;
+		struct bch_acct_nr_inodes		nr_inodes;
+		struct bch_acct_persistent_reserved	persistent_reserved;
 		struct bch_replicas_entry_v1	replicas;
-		struct bch_dev_data_type	dev_data_type;
+		struct bch_acct_dev_data_type	dev_data_type;
 		struct bch_acct_compression	compression;
 		struct bch_acct_snapshot	snapshot;
 		struct bch_acct_btree		btree;

fs/bcachefs/inode.c

@@ -731,10 +731,9 @@ int bch2_trigger_inode(struct btree_trans *trans,
 		bkey_s_to_inode_v3(new).v->bi_journal_seq = cpu_to_le64(trans->journal_res.seq);
 	}
 
-	s64 nr = bkey_is_inode(new.k) - bkey_is_inode(old.k);
-	if ((flags & (BTREE_TRIGGER_transactional|BTREE_TRIGGER_gc)) && nr) {
-		struct disk_accounting_pos acc = { .type = BCH_DISK_ACCOUNTING_nr_inodes };
-		int ret = bch2_disk_accounting_mod(trans, &acc, &nr, 1, flags & BTREE_TRIGGER_gc);
+	s64 nr[1] = { bkey_is_inode(new.k) - bkey_is_inode(old.k) };
+	if ((flags & (BTREE_TRIGGER_transactional|BTREE_TRIGGER_gc)) && nr[0]) {
+		int ret = bch2_disk_accounting_mod2(trans, flags & BTREE_TRIGGER_gc, nr, nr_inodes);
 		if (ret)
 			return ret;
 	}

fs/bcachefs/super.c

@@ -1990,15 +1990,12 @@ int bch2_dev_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 	mutex_unlock(&c->sb_lock);
 
 	if (ca->mi.freespace_initialized) {
-		struct disk_accounting_pos acc = {
-			.type = BCH_DISK_ACCOUNTING_dev_data_type,
-			.dev_data_type.dev = ca->dev_idx,
-			.dev_data_type.data_type = BCH_DATA_free,
-		};
 		u64 v[3] = { nbuckets - old_nbuckets, 0, 0 };
 
 		ret   = bch2_trans_commit_do(ca->fs, NULL, NULL, 0,
-				bch2_disk_accounting_mod(trans, &acc, v, ARRAY_SIZE(v), false)) ?:
+				bch2_disk_accounting_mod2(trans, false, v, dev_data_type,
+							  .dev = ca->dev_idx,
+							  .data_type = BCH_DATA_free)) ?:
 			bch2_dev_freespace_init(c, ca, old_nbuckets, nbuckets);
 		if (ret)
 			goto err;