diff --git a/libc/kernel/common/linux/backing-dev.h b/libc/kernel/common/linux/backing-dev.h
new file mode 100644
index 0000000..4996d2c
--- /dev/null
+++ b/libc/kernel/common/linux/backing-dev.h
@@ -0,0 +1,53 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef _LINUX_BACKING_DEV_H
+#define _LINUX_BACKING_DEV_H
+
+#include <asm/atomic.h>
+
+enum bdi_state {
+ BDI_pdflush,
+ BDI_write_congested,
+ BDI_read_congested,
+ BDI_unused,
+};
+
+typedef int (congested_fn)(void *, int);
+
+struct backing_dev_info {
+ unsigned long ra_pages;
+ unsigned long state;
+ unsigned int capabilities;
+ congested_fn *congested_fn;
+ void *congested_data;
+ void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
+ void *unplug_io_data;
+};
+
+#define BDI_CAP_NO_ACCT_DIRTY 0x00000001  
+#define BDI_CAP_NO_WRITEBACK 0x00000002  
+#define BDI_CAP_MAP_COPY 0x00000004  
+#define BDI_CAP_MAP_DIRECT 0x00000008  
+#define BDI_CAP_READ_MAP 0x00000010  
+#define BDI_CAP_WRITE_MAP 0x00000020  
+#define BDI_CAP_EXEC_MAP 0x00000040  
+#define BDI_CAP_VMFLAGS   (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
+
+#if defined(VM_MAYREAD) && BDI_CAP_READ_MAP != (VM_MAYREAD || BDI_CAP_WRITE_MAP != (VM_MAYWRITE || BDI_CAP_EXEC_MAP != VM_MAYEXEC))
+#error please change backing_dev_info::capabilities flags
+#endif
+
+#define bdi_cap_writeback_dirty(bdi)   (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))
+#define bdi_cap_account_dirty(bdi)   (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))
+#define mapping_cap_writeback_dirty(mapping)   bdi_cap_writeback_dirty((mapping)->backing_dev_info)
+#define mapping_cap_account_dirty(mapping)   bdi_cap_account_dirty((mapping)->backing_dev_info)
+#endif