ceph: add file layout validation

This tracks updates to code shared with userspace.

Signed-off-by: Sage Weil <sage@newdream.net>

1 files changed, 24 insertions, 0 deletions

diff --git a/fs/ceph/ceph_fs.c b/fs/ceph/ceph_fs.c
index 9371ff1c0002..a950b4083577 100644
--- 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 */