[svn-r5571] Purpose:

    Bug Fix (#709)/Code improvement.

Description:
    Allow chunks for chunked datasets to be cached when file is open for
    read-only access.

Platforms tested:
    IRIX64 6.5 (modi4) w/parallel

3 files changed, 12 insertions, 8 deletions

diff --git a/release_docs/RELEASE.txt b/release_docs/RELEASE.txt
index 5bf8427..9a6d09f 100644
--- a/release_docs/RELEASE.txt
+++ b/release_docs/RELEASE.txt
@@ -175,6 +175,8 @@ Documentation
 New Features
 ============
 
+    * Allow chunks in chunked datasets to be cached when file is opened for
+      read-only access (bug #709).  QAK - 2002/06/10
     * Added internal "small data" aggregation, which can reduce the number of
       actual I/O calls made, improving performance.  QAK - 2002/06/05
     * Improved internal metadata aggregation, which can reduce the number of
diff --git a/src/H5Distore.c b/src/H5Distore.c
index d966edd..03fd598 100644
--- a/src/H5Distore.c
+++ b/src/H5Distore.c
@@ -1875,11 +1875,12 @@ H5F_istore_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
         /*
-         * If MPIO is used, must bypass the chunk-cache scheme because other
-         * MPI processes could be writing to other elements in the same chunk.
+         * If MPIO is used and file can be written to, we must bypass the
+         * chunk-cache scheme because other MPI processes could be writing to
+         * other elements in the same chunk.
          * Do a direct write-through of only the elements requested.
          */
-            || IS_H5FD_MPIO(f)
+            || (IS_H5FD_MPIO(f) && (H5F_ACC_RDWR & f->shared->flags))
 #endif /* H5_HAVE_PARALLEL */
             ) {
             H5O_layout_t	l;	/* temporary layout */
@@ -2062,7 +2063,7 @@ H5F_istore_write(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
          * MPI processes could be writing to other elements in the same chunk.
          * Do a direct write-through of only the elements requested.
          */
-            || IS_H5FD_MPIO(f)
+            || (IS_H5FD_MPIO(f) && (H5F_ACC_RDWR & f->shared->flags))
 #endif /* H5_HAVE_PARALLEL */
             ) {
             H5O_layout_t	l;	/* temporary layout */
diff --git a/src/H5Fistore.c b/src/H5Fistore.c
index d966edd..03fd598 100644
--- a/src/H5Fistore.c
+++ b/src/H5Fistore.c
@@ -1875,11 +1875,12 @@ H5F_istore_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
         /*
-         * If MPIO is used, must bypass the chunk-cache scheme because other
-         * MPI processes could be writing to other elements in the same chunk.
+         * If MPIO is used and file can be written to, we must bypass the
+         * chunk-cache scheme because other MPI processes could be writing to
+         * other elements in the same chunk.
          * Do a direct write-through of only the elements requested.
          */
-            || IS_H5FD_MPIO(f)
+            || (IS_H5FD_MPIO(f) && (H5F_ACC_RDWR & f->shared->flags))
 #endif /* H5_HAVE_PARALLEL */
             ) {
             H5O_layout_t	l;	/* temporary layout */
@@ -2062,7 +2063,7 @@ H5F_istore_write(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
          * MPI processes could be writing to other elements in the same chunk.
          * Do a direct write-through of only the elements requested.
          */
-            || IS_H5FD_MPIO(f)
+            || (IS_H5FD_MPIO(f) && (H5F_ACC_RDWR & f->shared->flags))
 #endif /* H5_HAVE_PARALLEL */
             ) {
             H5O_layout_t	l;	/* temporary layout */