fs: implement zephyr fs api for virtiofs

This commit implements zephyr filesystem operations for virtiofs

Signed-off-by: Jakub Michalski <jmichalski@antmicro.com>
Signed-off-by: Filip Kokosinski <fkokosinski@antmicro.com>

Author: jmichalski-ant

include/zephyr/fs/fs.h

@@ -61,6 +61,9 @@ enum {
 	/** Identifier for in-tree Ext2 file system. */
 	FS_EXT2,
 
+	/** Identifier for in-tree Virtiofs file system. */
+	FS_VIRTIOFS,
+
 	/** Base identifier for external file systems. */
 	FS_TYPE_EXTERNAL_BASE,
 };

include/zephyr/fs/fs_interface.h

@@ -50,6 +50,10 @@ extern "C" {
 #define MAX_FILE_NAME 255
 #endif
 
+#if !defined(MAX_FILE_NAME) && defined(CONFIG_FILE_SYSTEM_VIRTIOFS)
+#define MAX_FILE_NAME 255
+#endif
+
 #if !defined(MAX_FILE_NAME) /* filesystem selection */
 /* Use standard 8.3 when no filesystem is explicitly selected */
 #define MAX_FILE_NAME 12

include/zephyr/fs/virtiofs.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (c) 2025 Antmicro <www.antmicro.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifndef ZEPHYR_INCLUDE_FS_VIRTIOFS_H_
+#define ZEPHYR_INCLUDE_FS_VIRTIOFS_H_
+
+#include <stdint.h>
+
+struct virtiofs_fs_data {
+	uint32_t max_write;
+};
+
+#endif /* ZEPHYR_INCLUDE_FS_VIRTIOFS_H_ */

subsys/fs/virtiofs/CMakeLists.txt

@@ -7,6 +7,7 @@ target_include_directories(VIRTIOFS INTERFACE ${CMAKE_CURRENT_SOURCE_DIR})
 zephyr_library()
 zephyr_library_sources(
   virtiofs.c
+  virtiofs_zfs.c
   fuse.c
 )