[PATCH 3/3] fuse: Add map_alignment for setup/remove mapping

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

This new FUSE_INIT field communicates the alignment constraint for
FUSE_SETUPMAPPING/FUSE_REMOVEMAPPING and allows the daemon to
constrain the addresses and file offsets chosen by the kernel.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 include/uapi/linux/fuse.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index f14eeb5cfc14..65c2136d112e 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -134,6 +134,7 @@
  *  7.31
  *  - add FUSE_WRITE_KILL_PRIV flag
  *  - add FUSE_SETUPMAPPING and FUSE_REMOVEMAPPING
+ *  - add map_alignment to fuse_init_out
  */
 
 #ifndef _LINUX_FUSE_H
@@ -275,6 +276,9 @@ struct fuse_file_lock {
  * FUSE_CACHE_SYMLINKS: cache READLINK responses
  * FUSE_NO_OPENDIR_SUPPORT: kernel supports zero-message opendir
  * FUSE_EXPLICIT_INVAL_DATA: only invalidate cached pages on explicit request
+ * FUSE_MAP_ALIGNMENT: init_out.map_alignment contains log2(byte alignment) for
+ *                     foffset and moffset fields in struct
+ *                     fuse_setupmapping_in and fuse_removemapping_one.
  */
 #define FUSE_ASYNC_READ		(1 << 0)
 #define FUSE_POSIX_LOCKS	(1 << 1)
@@ -302,6 +306,8 @@ struct fuse_file_lock {
 #define FUSE_CACHE_SYMLINKS	(1 << 23)
 #define FUSE_NO_OPENDIR_SUPPORT (1 << 24)
 #define FUSE_EXPLICIT_INVAL_DATA (1 << 25)
+#define FUSE_MAP_ALIGNMENT	(1 << 26)
+
 
 /**
  * CUSE INIT request/reply flags
@@ -655,7 +661,7 @@ struct fuse_init_out {
 	uint32_t	max_write;
 	uint32_t	time_gran;
 	uint16_t	max_pages;
-	uint16_t	padding;
+	uint16_t	map_alignment;
 	uint32_t	unused[8];
 };
 
-- 
2.21.0