ocfs2: Introduce dir free space list

The only operation which doesn't get faster with directory indexing is
insert, which still has to walk the entire unindexed directory portion to
find a free block. This patch provides an improvement in directory insert
performance by maintaining a singly linked list of directory leaf blocks
which have space for additional dirents.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/ocfs2/dir.h b/fs/ocfs2/dir.h
index 07b0416cdd42..e683f3deb645 100644
--- a/fs/ocfs2/dir.h
+++ b/fs/ocfs2/dir.h
@@ -39,11 +39,19 @@ struct ocfs2_dir_lookup_result {
 
         struct buffer_head              *dl_dx_root_bh; /* Root of indexed
                                                          * tree */
+
         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 */
+
+        struct buffer_head              *dl_prev_leaf_bh;/* Previous entry in
+                                                          * dir free space
+                                                          * list. NULL if
+                                                          * previous entry is
+                                                          * dx root block. */
 };
+
 void ocfs2_free_dir_lookup_result(struct ocfs2_dir_lookup_result *res);
 
 int ocfs2_find_entry(const char *name, int namelen,