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, 18 insertions, 3 deletions

diff --git a/fs/ocfs2/dir.h b/fs/ocfs2/dir.h
index 505d3af9bba5..d273aaef2ec2 100644
--- a/fs/ocfs2/dir.h
+++ b/fs/ocfs2/dir.h
@@ -26,9 +26,21 @@
 #ifndef OCFS2_DIR_H
 #define OCFS2_DIR_H
 
+struct ocfs2_dx_hinfo {
+        u32     major_hash;
+        u32     minor_hash;
+};
+
 struct ocfs2_dir_lookup_result {
-        struct buffer_head              *dl_leaf_bh;
-        struct ocfs2_dir_entry          *dl_entry;
+        struct buffer_head              *dl_leaf_bh;    /* Unindexed leaf
+                                                         * block */
+        struct ocfs2_dir_entry          *dl_entry;      /* Target dirent in
+                                                         * unindexed leaf */
+
+        struct buffer_head              *dl_dx_leaf_bh; /* Indexed leaf block */
+        struct ocfs2_dx_entry           *dl_dx_entry;   /* Target dx_entry in
+                                                         * indexed leaf */
+        struct ocfs2_dx_hinfo           dl_hinfo;       /* Name hash results */
 };
 void ocfs2_free_dir_lookup_result(struct ocfs2_dir_lookup_result *res);
 
@@ -85,7 +97,10 @@ int ocfs2_fill_new_dir(struct ocfs2_super *osb,
                        struct inode *parent,
                        struct inode *inode,
                        struct buffer_head *fe_bh,
-                       struct ocfs2_alloc_context *data_ac);
+                       struct ocfs2_alloc_context *data_ac,
+                       struct ocfs2_alloc_context *meta_ac);
+
+int ocfs2_dx_dir_truncate(struct inode *dir, struct buffer_head *di_bh);
 
 struct ocfs2_dir_block_trailer *ocfs2_dir_trailer_from_size(int blocksize,
                                                             void *data);