Kernel: Implement SYS_SYNC and add sync executable to userspace

You can (and have to) manually sync disk after writes to it.

kernel/include/kernel/Device/Device.h

@@ -13,6 +13,7 @@ namespace Kernel
 
 		virtual bool is_device() const override { return true; }
 		virtual bool is_partition() const { return false; }
+		virtual bool is_storage_device() const { return false; }
 
 		virtual dev_t rdev() const override = 0;
 

kernel/include/kernel/FS/DevFS/FileSystem.h

@@ -15,6 +15,7 @@ namespace Kernel
 		void initialize_device_updater();
 
 		void add_device(BAN::StringView path, BAN::RefPtr<RamInode>);
+		void for_each_device(const BAN::Function<BAN::Iteration(Device*)>& callback);
 
 		dev_t get_next_dev();
 

kernel/include/kernel/FS/RamFS/FileSystem.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <BAN/HashMap.h>
+#include <BAN/Iteration.h>
 #include <kernel/FS/FileSystem.h>
 #include <kernel/SpinLock.h>
 
@@ -25,7 +26,7 @@ namespace Kernel
 		blksize_t blksize() const { return m_blksize; }
 		ino_t next_ino() { return m_next_ino++; }
 
-		void for_each_inode(void (*callback)(BAN::RefPtr<RamInode>));
+		void for_each_inode(const BAN::Function<BAN::Iteration(BAN::RefPtr<RamInode>)>& callback);
 
 	protected:
 		RamFileSystem(size_t size)

kernel/include/kernel/Process.h

@@ -109,6 +109,8 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_fstatat(int fd, const char* path, struct stat* buf, int flag);
 		BAN::ErrorOr<long> sys_stat(const char* path, struct stat* buf, int flag);
 
+		BAN::ErrorOr<long> sys_sync();
+
 		BAN::ErrorOr<void> mount(BAN::StringView source, BAN::StringView target);
 
 		BAN::ErrorOr<long> sys_read_dir_entries(int fd, DirectoryEntryList* buffer, size_t buffer_size);

kernel/include/kernel/Storage/StorageDevice.h

@@ -77,6 +77,7 @@ namespace Kernel
 		const BAN::Vector<Partition*>& partitions() const { return m_partitions; }
 
 		BAN::ErrorOr<void> sync_disk_cache();
+		virtual bool is_storage_device() const override { return true; }
 
 	protected:
 		virtual BAN::ErrorOr<void> read_sectors_impl(uint64_t lba, uint8_t sector_count, uint8_t* buffer) = 0;