posix: set default stripe count

This commit fixes a bug that occurs when the dataset directory is
using the default striping count. In this case the ioctl may return
lmm_stripe_count = 0. Since hio assumes a stripe count >= 1 this was
triggering a problem when setting up the shared memory segment. To be
safe always set the default to 1 (or larger if writing shared files).

Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>

src/builtin-posix_component.c

@@ -236,6 +236,13 @@ static int builtin_posix_module_dataset_open (struct hio_module_t *module, hio_d
   }
 
   if (fs_attr->fs_flags & HIO_FS_SUPPORTS_STRIPING) {
+    if (HIO_SET_ELEMENT_UNIQUE == dataset->ds_mode) {
+      /* set defaults striping count */
+      fs_attr->fs_scount = 1;
+    } else {
+      fs_attr->fs_scount = max (1, (unsigned) ((float) fs_attr->fs_smax_count * 0.9));
+    }
+
     hioi_config_add (context, &dataset->ds_object, &fs_attr->fs_scount,
                      "stripe_count", HIO_CONFIG_TYPE_UINT32, NULL, "Stripe count for all dataset "
                      "data files", 0);

src/hio_dataset_shared.c

@@ -74,7 +74,7 @@ int hioi_dataset_buffer_flush (hio_dataset_t dataset) {
 
 int hioi_dataset_shared_init (hio_dataset_t dataset) {
   hio_context_t context = hioi_object_context (&dataset->ds_object);
-  int stripes = dataset->ds_fsattr.fs_scount;
+  int stripes = max (1, dataset->ds_fsattr.fs_scount);
   size_t ds_buffer_size = 512 * 1024;
   size_t control_block_size;
   MPI_Win shared_win;
@@ -109,7 +109,7 @@ int hioi_dataset_shared_init (hio_dataset_t dataset) {
     pthread_mutexattr_setpshared (&mutex_attr, PTHREAD_PROCESS_SHARED);
 
     /* fixme - not sure this is the right way to ensure stripe 0 mutex gets init'd */
-    for (int i = 0 ; i < max(1, stripes) ; ++i) {
+    for (int i = 0 ; i < stripes ; ++i) {
       pthread_mutex_init (&dataset->ds_shared_control->s_stripes[i].s_mutex, &mutex_attr);
       atomic_init (&dataset->ds_shared_control->s_stripes[i].s_index, 0);
     }

src/hio_fs.c

@@ -218,7 +218,7 @@ static int hioi_fs_query_lustre (const char *path, hio_fs_attr_t *fs_attr) {
     }
   }
 
-  fs_attr->fs_scount = lum->lmm_stripe_count;
+  fs_attr->fs_scount = lum->lmm_stripe_count ? lum->lmm_stripe_count : 1;
   fs_attr->fs_ssize  = lum->lmm_stripe_size;
 
   switch (lum->lmm_pattern) {
@@ -276,6 +276,10 @@ int hioi_fs_query (hio_context_t context, const char *path, hio_fs_attr_t *fs_at
     fs_attr->fs_btotal  = fsinfo.f_blocks;
     fs_attr->fs_bsize   = fsinfo.f_bsize;
 
+    /* set some reasonable defaults for striping parameters */
+    fs_attr->fs_scount = 1;
+    fs_attr->fs_ssize = fs_attr->fs_bsize;
+
     /* get filesytem specific data */
     switch (fsinfo.f_type) {
 #if defined(LL_SUPER_MAGIC)