fuse: add FUSE_AUTO_INVAL_DATA init flag

FUSE_AUTO_INVAL_DATA is provided to enable updated/auto cache
invalidation logic.
Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

fs/fuse/fuse_i.h

@@ -484,6 +484,9 @@ struct fuse_conn {
 	/** Is fallocate not implemented by fs? */
 	unsigned no_fallocate:1;
 
+	/** Use enhanced/automatic page cache invalidation. */
+	unsigned auto_inval_data:1;
+
 	/** The number of requests waiting for completion */
 	atomic_t num_waiting;
 

fs/fuse/inode.c

@@ -834,6 +834,8 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
 				fc->big_writes = 1;
 			if (arg->flags & FUSE_DONT_MASK)
 				fc->dont_mask = 1;
+			if (arg->flags & FUSE_AUTO_INVAL_DATA)
+				fc->auto_inval_data = 1;
 		} else {
 			ra_pages = fc->max_read / PAGE_CACHE_SIZE;
 			fc->no_lock = 1;
@@ -859,7 +861,7 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
 	arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
 	arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
 		FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
-		FUSE_FLOCK_LOCKS;
+		FUSE_FLOCK_LOCKS | FUSE_AUTO_INVAL_DATA;
 	req->in.h.opcode = FUSE_INIT;
 	req->in.numargs = 1;
 	req->in.args[0].size = sizeof(*arg);

include/linux/fuse.h

@@ -57,6 +57,9 @@
  *
  * 7.19
  *  - add FUSE_FALLOCATE
+ *
+ * 7.20
+ *  - add FUSE_AUTO_INVAL_DATA
  */
 
 #ifndef _LINUX_FUSE_H
@@ -88,7 +91,7 @@
 #define FUSE_KERNEL_VERSION 7
 
 /** Minor version number of this interface */
-#define FUSE_KERNEL_MINOR_VERSION 19
+#define FUSE_KERNEL_MINOR_VERSION 20
 
 /** The node ID of the root inode */
 #define FUSE_ROOT_ID 1
@@ -167,6 +170,7 @@ struct fuse_file_lock {
  * FUSE_EXPORT_SUPPORT: filesystem handles lookups of "." and ".."
  * FUSE_DONT_MASK: don't apply umask to file mode on create operations
  * FUSE_FLOCK_LOCKS: remote locking for BSD style file locks
+ * FUSE_AUTO_INVAL_DATA: automatically invalidate cached pages
  */
 #define FUSE_ASYNC_READ		(1 << 0)
 #define FUSE_POSIX_LOCKS	(1 << 1)
@@ -176,6 +180,7 @@ struct fuse_file_lock {
 #define FUSE_BIG_WRITES		(1 << 5)
 #define FUSE_DONT_MASK		(1 << 6)
 #define FUSE_FLOCK_LOCKS	(1 << 10)
+#define FUSE_AUTO_INVAL_DATA	(1 << 12)
 
 /**
  * CUSE INIT request/reply flags