Use fflush() before fsync() in rio.c.

Incremental flushing in rio.c is only used to avoid huge kernel buffers
synched to slow disks creating big latency spikes, so this fix has no
durability implications, however it is certainly more correct to make
sure that the FILE buffers are flushed to the kernel before calling
fsync on the file descriptor.

Thanks to Li Shao Kai for reporting this issue in the Redis mailing
list.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/rio.c b/src/rio.c
index 405e789e6..44f9b7a01 100644
--- a/src/rio.c
+++ b/src/rio.c
@@ -86,6 +86,7 @@ static size_t rioFileWrite(rio *r, const void *buf, size_t len) {
     if (r->io.file.autosync &&
         r->io.file.buffered >= r->io.file.autosync)
     {
+        fflush(r->io.file.fp);
         aof_fsync(fileno(r->io.file.fp));
         r->io.file.buffered = 0;
     }