[svn-r232] Problem: Parallel H5Fcreate failed if file doesnot exist. When the

file does not exist, the code tried to open the file with EXCL CREATE.
ROMIO cannot handle file-open with EXCL Create due to racing problem.
The first process creates the file which then fails all
other processes.

Solution: In the parallel code, turn on TRUNC mode to allow "late" open
calls to succeed too.  It is safe to force TRUNC mode since the file is
known non-existing at that point.  The MPIO implementation has to
provide the real solution.

Platform tested: O2K with ROMIO.

1 files changed, 13 insertions, 1 deletions

diff --git a/src/H5F.c b/src/H5F.c
index 7f83eb6..fd922a5 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -725,9 +725,21 @@ H5F_open(const H5F_low_class_t *type, const char *name, uintn flags,
             HRETURN_ERROR(H5E_FILE, H5E_BADVALUE, NULL,
                           "can't create file without write intent");
         }
+#ifdef HAVE_PARALLEL
+	/* ROMIO cannot handle file-open with EXCL Create due to racing problem */
+	/* The first process creates the file which then fails all */
+	/* other processes.  Turn on TRUNC bit here.  It does not matter */
+	/* since the file does not exist at this point. */
+        fd = H5F_low_open(type, name,
+                          H5F_ACC_WRITE | H5F_ACC_CREAT |
+			  (flags & H5F_ACC_TRUNC),
+                          &search);
+#else
         fd = H5F_low_open(type, name,
-                          H5F_ACC_WRITE | H5F_ACC_CREAT | H5F_ACC_EXCL,
+                          H5F_ACC_WRITE | H5F_ACC_CREAT |
+			  (flags & H5F_ACC_EXCL) | (flags & H5F_ACC_TRUNC),
                           &search);
+#endif /*HAVE_PARALLEL*/
         if (!fd) {
             HRETURN_ERROR(H5E_FILE, H5E_CANTCREATE, NULL,
                           "can't create file");