ceph: add dir_layout to inode

Add a ceph_dir_layout to the inode, and calculate dentry hash values based
on the parent directory's specified dir_hash function.  This is needed
because the old default Linux dcache hash function is extremely week and
leads to a poor distribution of files among dir fragments.

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

1 files changed, 13 insertions, 3 deletions

diff --git a/include/linux/ceph/ceph_fs.h b/include/linux/ceph/ceph_fs.h
index c3c74aef289d..09dcc0c2ffd5 100644
--- a/include/linux/ceph/ceph_fs.h
+++ b/include/linux/ceph/ceph_fs.h
@@ -43,6 +43,10 @@
 #define CEPH_FEATURE_NOSRCADDR      (1<<1)
 #define CEPH_FEATURE_MONCLOCKCHECK  (1<<2)
 #define CEPH_FEATURE_FLOCK          (1<<3)
+#define CEPH_FEATURE_SUBSCRIBE2     (1<<4)
+#define CEPH_FEATURE_MONNAMES       (1<<5)
+#define CEPH_FEATURE_RECONNECT_SEQ  (1<<6)
+#define CEPH_FEATURE_DIRLAYOUTHASH  (1<<7)
 
 
 /*
@@ -55,10 +59,10 @@ struct ceph_file_layout {
         __le32 fl_stripe_count;    /* over this many objects */
         __le32 fl_object_size;     /* until objects are this big, then move to
                                       new objects */
-        __le32 fl_cas_hash;        /* 0 = none; 1 = sha256 */
+        __le32 fl_cas_hash;        /* UNUSED.  0 = none; 1 = sha256 */
 
         /* pg -> disk layout */
-        __le32 fl_object_stripe_unit;  /* for per-object parity, if any */
+        __le32 fl_object_stripe_unit;  /* UNUSED.  for per-object parity, if any */
 
         /* object -> pg layout */
         __le32 fl_pg_preferred; /* preferred primary for pg (-1 for none) */
@@ -69,6 +73,12 @@ struct ceph_file_layout {
 
 int ceph_file_layout_is_valid(const struct ceph_file_layout *layout);
 
+struct ceph_dir_layout {
+        __u8   dl_dir_hash;   /* see ceph_hash.h for ids */
+        __u8   dl_unused1;
+        __u16  dl_unused2;
+        __u32  dl_unused3;
+} __attribute__ ((packed));
 
 /* crypto algorithms */
 #define CEPH_CRYPTO_NONE 0x0
@@ -457,7 +467,7 @@ struct ceph_mds_reply_inode {
         struct ceph_timespec rctime;
         struct ceph_frag_tree_head fragtree;  /* (must be at end of struct) */
 } __attribute__ ((packed));
-/* followed by frag array, then symlink string, then xattr blob */
+/* followed by frag array, symlink string, dir layout, xattr blob */
 
 /* reply_lease follows dname, and reply_inode */
 struct ceph_mds_reply_lease {