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From 06400ebc136bf44f1fa423159fae9cc9a4f6839d Mon Sep 17 00:00:00 2001
From: Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 27 Oct 2011 09:12:04 +0200
Subject: [PATCH] migration: flush migration data to disk.
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This patch increases robustness when migrating to a file with
two little changes:

 (1) Before closing the migration file handle checks if it happens to be
     a regular file and if so it issues a fsync.  This way the data is
     flushed to disk before qemu sends the migration completed event.
 (2) It adds error checking.  In case either fsync or close syscall
     fails pass up the error (and fail migration).

[ v2: return -errno instead of -1 ]

Cc: Juan Quintela <quintela@redhat.com>
Cc: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
(cherry picked from commit aab2293687ee54a409f3fb53a1ab3595b595e0fb)

Signed-off-by: Bruce Rogers <brogers@suse.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 migration-fd.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/migration-fd.c b/migration-fd.c
index 66d51c1..f986bdf 100644
--- a/migration-fd.c
+++ b/migration-fd.c
@@ -42,10 +42,31 @@ static int fd_write(FdMigrationState *s, const void * buf, size_t size)
 
 static int fd_close(FdMigrationState *s)
 {
+    struct stat st;
+    int ret;
+
     DPRINTF("fd_close\n");
     if (s->fd != -1) {
-        close(s->fd);
+        ret = fstat(s->fd, &st);
+        if (ret == 0 && S_ISREG(st.st_mode)) {
+            /*
+             * If the file handle is a regular file make sure the
+             * data is flushed to disk before signaling success.
+             */
+            ret = fsync(s->fd);
+            if (ret != 0) {
+                ret = -errno;
+                perror("migration-fd: fsync");
+                return ret;
+            }
+        }
+        ret = close(s->fd);
         s->fd = -1;
+        if (ret != 0) {
+            ret = -errno;
+            perror("migration-fd: close");
+            return ret;
+        }
     }
     return 0;
 }
-- 
1.7.11.2