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>
diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index c17bd6f..07a7501 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -266,6 +266,15 @@
return n;
}
+int os_sync_file(int fd)
+{
+ int n = fsync(fd);
+
+ if (n < 0)
+ return -errno;
+ return n;
+}
+
int os_file_size(const char *file, unsigned long long *size_out)
{
struct uml_stat buf;