From 805f11a0d515658106bfbfadceff0eb30bd90ad2 Mon Sep 17 00:00:00 2001
From: Richard Weinberger <richard@nod.at>
Date: Sun, 18 Aug 2013 13:30:06 +0200
Subject: um: ubd: Add REQ_FLUSH suppport

UML's block device driver does not support write barriers,
to support this this patch adds REQ_FLUSH suppport.
Every time the block layer sends a REQ_FLUSH we fsync() now
our backing file to guarantee data consistency.

Reported-and-tested-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 arch/um/include/shared/os.h | 1 +
 1 file changed, 1 insertion(+)

(limited to 'arch/um/include')

diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index c70a234a3f8c..e98303925cc5 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -141,6 +141,7 @@ extern int os_seek_file(int fd, unsigned long long offset);
 extern int os_open_file(const char *file, struct openflags flags, int mode);
 extern int os_read_file(int fd, void *buf, int len);
 extern int os_write_file(int fd, const void *buf, int count);
+extern int os_sync_file(int fd);
 extern int os_file_size(const char *file, unsigned long long *size_out);
 extern int os_file_modtime(const char *file, unsigned long *modtime);
 extern int os_pipe(int *fd, int stream, int close_on_exec);
-- 
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