fs: Add FileSystem::get_block_device

features/filesystem/FileSystem.cpp

@@ -44,6 +44,11 @@ int FileSystem::mkdir(const char *path, mode_t mode)
     return -ENOSYS;
 }
 
+BlockDevice *FileSystem::get_block_device() const
+{
+    return NULL;
+}
+
 int FileSystem::file_sync(fs_file_t file)
 {
     return 0;

features/filesystem/FileSystem.h

@@ -99,6 +99,13 @@ class FileSystem : public FileSystemLike {
      */
     virtual int mkdir(const char *path, mode_t mode);
 
+    /** Get the underlying block device
+     *
+     *  @return         The underlying block device, or NULL if no block
+     *                  device has been mounted
+     */
+    virtual BlockDevice *get_block_device() const;
+
 protected:
     friend class File;
     friend class Dir;

features/filesystem/fat/FATFileSystem.cpp

@@ -293,6 +293,15 @@ int FATFileSystem::unmount()
     return fat_error_remap(res);
 }
 
+BlockDevice *FATFileSystem::get_block_device() const
+{
+    if (_id != -1) {
+        return _ffs[_id];
+    } else {
+        return NULL;
+    }
+}
+
 /* See http://elm-chan.org/fsw/ff/en/mkfs.html for details of f_mkfs() and
  * associated arguments. */
 int FATFileSystem::format(BlockDevice *bd, int allocation_unit) {

features/filesystem/fat/FATFileSystem.h

@@ -106,6 +106,13 @@ class FATFileSystem : public FileSystem {
      */
     virtual int mkdir(const char *path, mode_t mode);
 
+    /** Get the underlying block device
+     *
+     *  @return         The underlying block device, or NULL if no block
+     *                  device has been mounted
+     */
+    virtual BlockDevice *get_block_device() const;
+
 protected:
     /** Open a file on the filesystem
      *