rbd.cc: fix error handling

Fix undead code. Get error code from write_fd() before check
the result against < 0.

CID 1019550 Logically dead code (CWE-561)

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>

diff --git a/src/rbd.cc b/src/rbd.cc
index 79860c2d772e2d0e89fcd00f8a927f76be02b567..3e586bd4dcbab0eb12b9251fc640821cde5c777f 100644 (file)
--- a/src/rbd.cc
+++ b/src/rbd.cc
@@ -1141,7 +1141,7 @@ static int do_export_diff(librbd::Image& image, const char *fromsnapname,
     __u8 tag = 'e';
     bufferlist bl;
     ::encode(tag, bl);
-    bl.write_fd(fd);
+    r = bl.write_fd(fd);
     if (r < 0)
       return r;
   }