ceph: add file layout validation

[safe/jmp/linux-2.6] / fs / ceph / ceph_fs.c

diff --git a/fs/ceph/ceph_fs.c b/fs/ceph/ceph_fs.c
index 9371ff1..a950b40 100644 (file)
--- a/fs/ceph/ceph_fs.c
+++ b/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 */