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Subject[PATCH] fuse: reserve byteswapped init opcodes
virtio fs tunnels fuse over a virtio channel.  One issue is two sides
might be speaking different endian-ness. To detects this,
host side looks at the opcode value in the FUSE_INIT command.
Works fine at the moment but might fail if a future version
of fuse will use such an opcode for initialization.
Let's reserve this opcode so we remember and don't do this.

Same for CUSE_INIT.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
include/uapi/linux/fuse.h | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index 2971d29a42e4..f042e63f4aa0 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -425,6 +425,10 @@ enum fuse_opcode {

/* CUSE specific operations */
CUSE_INIT = 4096,
+
+ /* Reserved opcodes: helpful to detect structure endian-ness */
+ FUSE_INIT_BSWAP_RESERVED = 26 << 24,
+ CUSE_INIT_BSWAP_RESERVED = 16 << 16,
};

enum fuse_notify_code {
--
MST
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