trim: Target SCSI UNMAP command instead of WRITE SAME.

* The UNMAP command is theoretically much faster, as it can get many block
  ranges instead of just a single range.
* Furthermore, the ATA TRIM command resembles it much better.
* Therefore, fs_trim_data now gets an array of ranges, and we use SCSI UNMAP
  to trim.
* Updated BFS code to collect array ranges to fully support the new
  fs_trim_data possibilities.

headers/private/kernel/util/fs_trim_support.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2013, Axel Dörfler, [email protected].
+ * Distributed under the terms of the MIT license.
+ */
+#ifndef _FS_TRIM_SUPPORT_H
+#define _FS_TRIM_SUPPORT_H
+
+
+#include <Drivers.h>
+
+#include <kernel.h>
+
+
+static inline status_t
+copy_trim_data_from_user(void* buffer, size_t size, fs_trim_data*& _trimData)
+{
+	if (!IS_USER_ADDRESS(buffer))
+		return B_BAD_ADDRESS;
+
+	uint32 count;
+	if (user_memcpy(&count, buffer, sizeof(count)) != B_OK)
+		return B_BAD_ADDRESS;
+
+	size_t bytes = (count - 1) * sizeof(uint64) * 2 + sizeof(fs_trim_data);
+	if (bytes > size)
+		return B_BAD_VALUE;
+
+	void* trimBuffer = malloc(bytes);
+	if (trimBuffer == NULL)
+		return B_NO_MEMORY;
+
+	if (user_memcpy(trimBuffer, buffer, bytes) != B_OK)
+		return B_BAD_ADDRESS;
+
+	_trimData = (fs_trim_data*)trimBuffer;
+	return B_OK;
+}
+
+
+static inline status_t
+copy_trim_data_to_user(void* buffer, fs_trim_data* trimData)
+{
+	// Do not copy any ranges
+	return user_memcpy(buffer, trimData, sizeof(uint64) * 2);
+}
+
+
+#endif	// _FS_TRIM_SUPPORT_H