ceph: add file layout validation

This tracks updates to code shared with userspace.
Signed-off-by: Sage Weil <sage@newdream.net>

fs/ceph/ceph_fs.c

@@ -3,6 +3,30 @@
  */
 #include "types.h"
 
+/*
+ * return true if @layout appears to be valid
+ */
+int ceph_file_layout_is_valid(const struct ceph_file_layout *layout)
+{
+	__u32 su = le32_to_cpu(layout->fl_stripe_unit);
+	__u32 sc = le32_to_cpu(layout->fl_stripe_count);
+	__u32 os = le32_to_cpu(layout->fl_object_size);
+
+	/* stripe unit, object size must be non-zero, 64k increment */
+	if (!su || (su & (CEPH_MIN_STRIPE_UNIT-1)))
+		return 0;
+	if (!os || (os & (CEPH_MIN_STRIPE_UNIT-1)))
+		return 0;
+	/* object size must be a multiple of stripe unit */
+	if (os < su || os % su)
+		return 0;
+	/* stripe count must be non-zero */
+	if (!sc)
+		return 0;
+	return 1;
+}
+
+
 int ceph_flags_to_mode(int flags)
 {
 #ifdef O_DIRECTORY  /* fixme */

fs/ceph/ceph_fs.h

@@ -72,7 +72,9 @@ struct ceph_file_layout {
 	__le32 fl_pg_pool;      /* namespace, crush ruleset, rep level */
 } __attribute__ ((packed));
 
+#define CEPH_MIN_STRIPE_UNIT 65536
 
+int ceph_file_layout_is_valid(const struct ceph_file_layout *layout);
 
 
 /*********************************************