commit a5813077aac7865f69b7ee46a594f3705429f7cd
author Stefan Hajnoczi <stefanha@redhat.com> Thu Aug 22 11:29:03 2013 +0200
committer Stefan Hajnoczi <stefanha@redhat.com> Wed Sep 18 15:34:51 2013 +0200
tree 903e1d953b00ac44f65b6ef88c3d93bac0d26b4b
parent 975a0015ee380f49a3be744279a6a06ab97e960a

osdep: warn if open(O_DIRECT) on fails with EINVAL

Print a warning when opening a file O_DIRECT fails with EINVAL.  This
saves users a lot of time trying to figure out the EINVAL error, which
is typical when attempting to open a file O_DIRECT on Linux tmpfs.

Reported-by: Deepak C Shetty <deepakcs@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

util/osdep.c

diff --git a/util/osdep.c b/util/osdep.c
index 685c8ae..62072b4 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -207,6 +207,13 @@
     }
 #endif
 
+#ifdef O_DIRECT
+    if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) {
+        error_report("file system may not support O_DIRECT");
+        errno = EINVAL; /* in case it was clobbered */
+    }
+#endif /* O_DIRECT */
+
     return ret;
 }