fuse: add FUSE_CONN_FLAG_NO_INTERRUPT conn flag

fuse_set_conn_flag() collects the libfuse-side connection hints that are
not negotiated with the kernel. no_interrupt was the one such hint still
set only by direct field assignment.

Define FUSE_CONN_FLAG_NO_INTERRUPT alongside FUSE_CONN_FLAG_SINGLE_ISSUER
and map it onto conn->no_interrupt in the same switch, and convert the
example init() handlers to set it through the setter.

Signed-off-by: Bernd Schubert <bernd@bsbernd.com>

example/cuse.c

@@ -92,7 +92,7 @@ static void cusexmp_init(void *userdata, struct fuse_conn_info *conn)
 	(void)userdata;
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 }
 
 static void cusexmp_open(fuse_req_t req, struct fuse_file_info *fi)

example/hello_ll.c

@@ -65,7 +65,7 @@ static void hello_ll_init(void *userdata, struct fuse_conn_info *conn)
 	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_SINGLE_ISSUER);
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 
 	/* Test setting flags the old way */
 	conn->want = FUSE_CAP_ASYNC_READ;

example/hello_ll_uds.c

@@ -82,7 +82,7 @@ static void hello_ll_init(void *userdata, struct fuse_conn_info *conn)
 	(void)userdata;
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 }
 
 static void hello_ll_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)

example/notify_inval_entry.c

@@ -155,7 +155,7 @@ static void tfs_init(void *userdata, struct fuse_conn_info *conn) {
 	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_SINGLE_ISSUER);
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 }
 
 static void tfs_lookup(fuse_req_t req, fuse_ino_t parent,

example/notify_inval_inode.c

@@ -129,7 +129,7 @@ static void tfs_init(void *userdata, struct fuse_conn_info *conn) {
 	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_SINGLE_ISSUER);
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 }
 
 static void tfs_destroy(void *userarg)

example/notify_prune.c

@@ -140,7 +140,7 @@ static void tfs_init(void *userdata, struct fuse_conn_info *conn)
 	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_SINGLE_ISSUER);
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 }
 
 static void tfs_destroy(void *userarg)

example/notify_store_retrieve.c

@@ -138,7 +138,7 @@ static void tfs_init(void *userdata, struct fuse_conn_info *conn) {
 	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_SINGLE_ISSUER);
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 }
 
 static void tfs_lookup(fuse_req_t req, fuse_ino_t parent,

example/passthrough_hp.cc

@@ -249,7 +249,7 @@ static void sfs_init(void *userdata, fuse_conn_info *conn)
 	fuse_set_feature_flag(conn, FUSE_CAP_NO_EXPORT_SUPPORT);
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 
 	/* Try a large IO by default */
 	conn->max_write = 4 * 1024 * 1024;

example/passthrough_ll.c

@@ -184,7 +184,7 @@ static void lo_init(void *userdata,
 	}
 
 	/* Disable the receiving and processing of FUSE_INTERRUPT requests */
-	conn->no_interrupt = 1;
+	fuse_set_conn_flag(conn, FUSE_CONN_FLAG_NO_INTERRUPT);
 }
 
 static void lo_destroy(void *userdata)

include/fuse_common.h

@@ -1151,10 +1151,13 @@ void fuse_unset_feature_flag(struct fuse_conn_info *conn, uint64_t flag);
  */
 bool fuse_get_feature_flag(const struct fuse_conn_info *conn, uint64_t flag);
 
-/* The file system replies to requests from the same thread that received them,
- * allowing io-uring optimizations
+/**
+ * FUSE_CONN_FLAG_SINGLE_ISSUER: Reply from the same thread that received
+ *                               requests, which allows io-uring optimizations
+ * FUSE_CONN_FLAG_NO_INTERRUPT: Disable fuse interrupt handling and (libfuse overhead)
  */
 #define FUSE_CONN_FLAG_SINGLE_ISSUER (1u << 0)
+#define FUSE_CONN_FLAG_NO_INTERRUPT (1u << 1)
 
 /**
  * Set a libfuse connection flag (a FUSE_CONN_FLAG_* value). Unlike

lib/fuse_lowlevel.c

@@ -2706,6 +2706,9 @@ bool fuse_set_conn_flag(struct fuse_conn_info *conn, uint64_t flag)
 	case FUSE_CONN_FLAG_SINGLE_ISSUER:
 		conn->io_uring_single_issuer = 1;
 		return true;
+	case FUSE_CONN_FLAG_NO_INTERRUPT:
+		conn->no_interrupt = 1;
+		return true;
 	default:
 		return false;
 	}