1 files changed, 35 insertions, 0 deletions
diff --git a/fs/bcachefs/bkey_on_stack.h b/fs/bcachefs/bkey_on_stack.h
new file mode 100644
index 000000000000..d4739038323f
--- /dev/null
+++ b/fs/bcachefs/bkey_on_stack.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BCACHEFS_BKEY_ON_STACK_H
+#define _BCACHEFS_BKEY_ON_STACK_H
+
+#include "bcachefs.h"
+
+struct bkey_on_stack {
+	struct bkey_i	*k;
+	u64		onstack[12];
+};
+
+static inline void bkey_on_stack_realloc(struct bkey_on_stack *s,
+					 struct bch_fs *c, unsigned u64s)
+{
+	if (s->k == (void *) s->onstack &&
+	    u64s > ARRAY_SIZE(s->onstack)) {
+		s->k = mempool_alloc(&c->large_bkey_pool, GFP_NOFS);
+		memcpy(s->k, s->onstack, sizeof(s->onstack));
+	}
+}
+
+static inline void bkey_on_stack_init(struct bkey_on_stack *s)
+{
+	s->k = (void *) s->onstack;
+}
+
+static inline void bkey_on_stack_exit(struct bkey_on_stack *s,
+				      struct bch_fs *c)
+{
+	if (s->k != (void *) s->onstack)
+		mempool_free(s->k, &c->large_bkey_pool);
+	s->k = NULL;
+}
+
+#endif /* _BCACHEFS_BKEY_ON_STACK_H */