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, 4 insertions, 1 deletions

diff --git a/fs/ocfs2/ocfs2_fs.h b/fs/ocfs2/ocfs2_fs.h
index 1d1c54ea5bc4..d549b1799a61 100644
--- a/fs/ocfs2/ocfs2_fs.h
+++ b/fs/ocfs2/ocfs2_fs.h
@@ -416,6 +416,7 @@ static struct ocfs2_system_inode_info ocfs2_system_inodes[NUM_SYSTEM_INODES] = {
 #define OCFS2_DIR_REC_LEN(name_len)     (((name_len) + OCFS2_DIR_MEMBER_LEN + \
                                           OCFS2_DIR_ROUND) & \
                                          ~OCFS2_DIR_ROUND)
+#define OCFS2_DIR_MIN_REC_LEN   OCFS2_DIR_REC_LEN(1)
 
 #define OCFS2_LINK_MAX          32000
 
@@ -842,7 +843,9 @@ struct ocfs2_dx_root_block {
         __le16          dr_reserved1;
         __le64          dr_dir_blkno;           /* Pointer to parent inode */
         __le64          dr_reserved2;
-        __le64          dr_reserved3[16];
+        __le64          dr_free_blk;            /* Pointer to head of free
+                                                 * unindexed block list. */
+        __le64          dr_reserved3[15];
         union {
                 struct ocfs2_extent_list dr_list; /* Keep this aligned to 128
                                                    * bits for maximum space