1 files changed, 55 insertions, 0 deletions
diff --git a/libbcachefs/nocow_locking.h b/libbcachefs/nocow_locking.h
new file mode 100644
index 00000000..09ab85ac
--- /dev/null
+++ b/libbcachefs/nocow_locking.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHEFS_NOCOW_LOCKING_H
+#define _BCACHEFS_NOCOW_LOCKING_H
+
+#include "bcachefs_format.h"
+#include "two_state_shared_lock.h"
+
+#include <linux/siphash.h>
+
+#define BUCKET_NOCOW_LOCKS		(1U << 10)
+
+struct bucket_nocow_lock_table {
+	siphash_key_t			key;
+	two_state_lock_t		l[BUCKET_NOCOW_LOCKS];
+};
+
+#define BUCKET_NOCOW_LOCK_UPDATE	(1 << 0)
+
+static inline two_state_lock_t *bucket_nocow_lock(struct bucket_nocow_lock_table *t,
+						  struct bpos bucket)
+{
+	u64 dev_bucket = bucket.inode << 56 | bucket.offset;
+	unsigned h = siphash_1u64(dev_bucket, &t->key);
+
+	return t->l + (h & (BUCKET_NOCOW_LOCKS - 1));
+}
+
+static inline bool bch2_bucket_nocow_is_locked(struct bucket_nocow_lock_table *t,
+					       struct bpos bucket)
+{
+	two_state_lock_t *l = bucket_nocow_lock(t, bucket);
+
+	return atomic_long_read(&l->v) != 0;
+}
+
+static inline void bch2_bucket_nocow_unlock(struct bucket_nocow_lock_table *t,
+					    struct bpos bucket, int flags)
+{
+	two_state_lock_t *l = bucket_nocow_lock(t, bucket);
+
+	bch2_two_state_unlock(l, flags & BUCKET_NOCOW_LOCK_UPDATE);
+}
+
+void __bch2_bucket_nocow_lock(struct bucket_nocow_lock_table *, struct bpos, int);
+
+static inline void bch2_bucket_nocow_lock(struct bucket_nocow_lock_table *t,
+					  struct bpos bucket, int flags)
+{
+	two_state_lock_t *l = bucket_nocow_lock(t, bucket);
+
+	if (!bch2_two_state_trylock(l, flags & BUCKET_NOCOW_LOCK_UPDATE))
+		__bch2_bucket_nocow_lock(t, bucket, flags);
+}
+
+#endif /* _BCACHEFS_NOCOW_LOCKING_H */