ocfs2: Add a name indexed b-tree to directory inodes

This patch makes use of Ocfs2's flexible btree code to add an additional
tree to directory inodes. The new tree stores an array of small,
fixed-length records in each leaf block. Each record stores a hash value,
and pointer to a block in the traditional (unindexed) directory tree where a
dirent with the given name hash resides. Lookup exclusively uses this tree
to find dirents, thus providing us with constant time name lookups.

Some of the hashing code was copied from ext3. Unfortunately, it has lots of
unfixed checkpatch errors. I left that as-is so that tracking changes would
be easier.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Acked-by: Joel Becker <joel.becker@oracle.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 4eaf0e602bd0..53892d874ffc 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1918,6 +1918,12 @@ static int ocfs2_initialize_super(struct super_block *sb,
         bbits = le32_to_cpu(di->id2.i_super.s_blocksize_bits);
         sb->s_maxbytes = ocfs2_max_file_offset(bbits, cbits);
 
+        osb->osb_dx_mask = (1 << (cbits - bbits)) - 1;
+
+        for (i = 0; i < 3; i++)
+                osb->osb_dx_seed[i] = le32_to_cpu(di->id2.i_super.s_dx_seed[i]);
+        osb->osb_dx_seed[3] = le32_to_cpu(di->id2.i_super.s_uuid_hash);
+
         osb->sb = sb;
         /* Save off for ocfs2_rw_direct */
         osb->s_sectsize_bits = blksize_bits(sector_size);