[RFC PATCH v4 01/36] fuse-bpf: Update fuse side uapi

[Daniel Rosenberg <drosen@google.com>]

Adds structures which will be used to inform fuse about what it is being
stacked on top of. Once filters are in place, error_in will inform the
post filter if the backing call returned an error.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
 include/uapi/linux/fuse.h | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index e7418d15fe39..0c0a9a8b5c26 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -654,6 +654,29 @@ struct fuse_entry_out {
 	struct fuse_attr attr;
 };
 
+#define FUSE_BPF_MAX_ENTRIES	2
+
+enum fuse_bpf_type {
+	FUSE_ENTRY_BACKING		= 1,
+	FUSE_ENTRY_BPF			= 2,
+	FUSE_ENTRY_REMOVE_BACKING	= 3,
+	FUSE_ENTRY_REMOVE_BPF		= 4,
+};
+
+#define BPF_FUSE_NAME_MAX 15
+
+struct fuse_bpf_entry_out {
+	uint32_t	entry_type;
+	uint32_t	unused;
+	union {
+		struct {
+			uint64_t unused2;
+			uint64_t fd;
+		};
+		char name[BPF_FUSE_NAME_MAX + 1];
+	};
+};
+
 struct fuse_forget_in {
 	uint64_t	nlookup;
 };
-- 
2.44.0.478.gd926399ef9-goog