1 files changed, 16 insertions, 0 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index 4910a36f516e..cd223190c4e9 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -575,6 +575,21 @@ ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos,
  * possibly a read which collects the result - which is stored in a
  * file-local buffer.
  */
+
+void simple_transaction_set(struct file *file, size_t n)
+{
+        struct simple_transaction_argresp *ar = file->private_data;
+
+        BUG_ON(n > SIMPLE_TRANSACTION_LIMIT);
+
+        /*
+         * The barrier ensures that ar->size will really remain zero until
+         * ar->data is ready for reading.
+         */
+        smp_mb();
+        ar->size = n;
+}
+
 char *simple_transaction_get(struct file *file, const char __user *buf, size_t size)
 {
         struct simple_transaction_argresp *ar;
@@ -820,6 +835,7 @@ EXPORT_SYMBOL(simple_sync_file);
 EXPORT_SYMBOL(simple_unlink);
 EXPORT_SYMBOL(simple_read_from_buffer);
 EXPORT_SYMBOL(memory_read_from_buffer);
+EXPORT_SYMBOL(simple_transaction_set);
 EXPORT_SYMBOL(simple_transaction_get);
 EXPORT_SYMBOL(simple_transaction_read);
 EXPORT_SYMBOL(simple_transaction_release);