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>

4 files changed, 490 insertions, 93 deletions

diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c
index 47de64988b11..52df9125a79d 100644
--- a/fs/ocfs2/dir.c
+++ b/fs/ocfs2/dir.c
@@ -80,22 +80,36 @@ static int ocfs2_do_extend_dir(struct super_block *sb,
                                struct ocfs2_alloc_context *data_ac,
                                struct ocfs2_alloc_context *meta_ac,
                                struct buffer_head **new_bh);
+static int ocfs2_dir_indexed(struct inode *inode);
 
 /*
  * These are distinct checks because future versions of the file system will
  * want to have a trailing dirent structure independent of indexing.
  */
-static int ocfs2_dir_has_trailer(struct inode *dir)
+static int ocfs2_supports_dir_trailer(struct inode *dir)
 {
+        struct ocfs2_super *osb = OCFS2_SB(dir->i_sb);
+
         if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL)
                 return 0;
 
-        return ocfs2_meta_ecc(OCFS2_SB(dir->i_sb));
+        return ocfs2_meta_ecc(osb) || ocfs2_dir_indexed(dir);
 }
 
-static int ocfs2_supports_dir_trailer(struct ocfs2_super *osb)
+/*
+ * "new' here refers to the point at which we're creating a new
+ * directory via "mkdir()", but also when we're expanding an inline
+ * directory. In either case, we don't yet have the indexing bit set
+ * on the directory, so the standard checks will fail in when metaecc
+ * is turned off. Only directory-initialization type functions should
+ * use this then. Everything else wants ocfs2_supports_dir_trailer()
+ */
+static int ocfs2_new_dir_wants_trailer(struct inode *dir)
 {
-        return ocfs2_meta_ecc(osb);
+        struct ocfs2_super *osb = OCFS2_SB(dir->i_sb);
+
+        return ocfs2_meta_ecc(osb) ||
+                ocfs2_supports_indexed_dirs(osb);
 }
 
 static inline unsigned int ocfs2_dir_trailer_blk_off(struct super_block *sb)
@@ -127,7 +141,7 @@ static int ocfs2_skip_dir_trailer(struct inode *dir,
 {
         unsigned long toff = blklen - sizeof(struct ocfs2_dir_block_trailer);
 
-        if (!ocfs2_dir_has_trailer(dir))
+        if (!ocfs2_supports_dir_trailer(dir))
                 return 0;
 
         if (offset != toff)
@@ -137,7 +151,7 @@ static int ocfs2_skip_dir_trailer(struct inode *dir,
 }
 
 static void ocfs2_init_dir_trailer(struct inode *inode,
-                                   struct buffer_head *bh)
+                                   struct buffer_head *bh, u16 rec_len)
 {
         struct ocfs2_dir_block_trailer *trailer;
 
@@ -147,6 +161,42 @@ static void ocfs2_init_dir_trailer(struct inode *inode,
                         cpu_to_le16(sizeof(struct ocfs2_dir_block_trailer));
         trailer->db_parent_dinode = cpu_to_le64(OCFS2_I(inode)->ip_blkno);
         trailer->db_blkno = cpu_to_le64(bh->b_blocknr);
+        trailer->db_free_rec_len = cpu_to_le16(rec_len);
+}
+/*
+ * Link an unindexed block with a dir trailer structure into the index free
+ * list. This function will modify dirdata_bh, but assumes you've already
+ * passed it to the journal.
+ */
+static int ocfs2_dx_dir_link_trailer(struct inode *dir, handle_t *handle,
+                                     struct buffer_head *dx_root_bh,
+                                     struct buffer_head *dirdata_bh)
+{
+        int ret;
+        struct ocfs2_dx_root_block *dx_root;
+        struct ocfs2_dir_block_trailer *trailer;
+
+        ret = ocfs2_journal_access_dr(handle, dir, dx_root_bh,
+                                      OCFS2_JOURNAL_ACCESS_WRITE);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+        trailer = ocfs2_trailer_from_bh(dirdata_bh, dir->i_sb);
+        dx_root = (struct ocfs2_dx_root_block *)dx_root_bh->b_data;
+
+        trailer->db_free_next = dx_root->dr_free_blk;
+        dx_root->dr_free_blk = cpu_to_le64(dirdata_bh->b_blocknr);
+
+        ocfs2_journal_dirty(handle, dx_root_bh);
+
+out:
+        return ret;
+}
+
+static int ocfs2_free_list_at_root(struct ocfs2_dir_lookup_result *res)
+{
+        return res->dl_prev_leaf_bh == NULL;
 }
 
 void ocfs2_free_dir_lookup_result(struct ocfs2_dir_lookup_result *res)
@@ -154,6 +204,7 @@ void ocfs2_free_dir_lookup_result(struct ocfs2_dir_lookup_result *res)
         brelse(res->dl_dx_root_bh);
         brelse(res->dl_leaf_bh);
         brelse(res->dl_dx_leaf_bh);
+        brelse(res->dl_prev_leaf_bh);
 }
 
 static int ocfs2_dir_indexed(struct inode *inode)
@@ -484,7 +535,7 @@ static int ocfs2_read_dir_block(struct inode *inode, u64 v_block,
         }
 
         if (!(flags & OCFS2_BH_READAHEAD) &&
-            ocfs2_dir_has_trailer(inode)) {
+            ocfs2_supports_dir_trailer(inode)) {
                 rc = ocfs2_check_dir_trailer(inode, tmp);
                 if (rc) {
                         if (!*bh)
@@ -1150,6 +1201,47 @@ bail:
         return status;
 }
 
+static unsigned int ocfs2_figure_dirent_hole(struct ocfs2_dir_entry *de)
+{
+        unsigned int hole;
+
+        if (le64_to_cpu(de->inode) == 0)
+                hole = le16_to_cpu(de->rec_len);
+        else
+                hole = le16_to_cpu(de->rec_len) -
+                        OCFS2_DIR_REC_LEN(de->name_len);
+
+        return hole;
+}
+
+static int ocfs2_find_max_rec_len(struct super_block *sb,
+                                  struct buffer_head *dirblock_bh)
+{
+        int size, this_hole, largest_hole = 0;
+        char *trailer, *de_buf, *limit, *start = dirblock_bh->b_data;
+        struct ocfs2_dir_entry *de;
+
+        trailer = (char *)ocfs2_trailer_from_bh(dirblock_bh, sb);
+        size = ocfs2_dir_trailer_blk_off(sb);
+        limit = start + size;
+        de_buf = start;
+        de = (struct ocfs2_dir_entry *)de_buf;
+        do {
+                if (de_buf != trailer) {
+                        this_hole = ocfs2_figure_dirent_hole(de);
+                        if (this_hole > largest_hole)
+                                largest_hole = this_hole;
+                }
+
+                de_buf += le16_to_cpu(de->rec_len);
+                de = (struct ocfs2_dir_entry *)de_buf;
+        } while (de_buf < limit);
+
+        if (largest_hole >= OCFS2_DIR_MIN_REC_LEN)
+                return largest_hole;
+        return 0;
+}
+
 static void ocfs2_dx_list_remove_entry(struct ocfs2_dx_entry_list *entry_list,
                                        int index)
 {
@@ -1171,14 +1263,26 @@ clear:
 static int ocfs2_delete_entry_dx(handle_t *handle, struct inode *dir,
                                  struct ocfs2_dir_lookup_result *lookup)
 {
-        int ret, index;
+        int ret, index, max_rec_len, add_to_free_list = 0;
         struct buffer_head *dx_root_bh = lookup->dl_dx_root_bh;
         struct buffer_head *leaf_bh = lookup->dl_leaf_bh;
         struct ocfs2_dx_leaf *dx_leaf;
         struct ocfs2_dx_entry *dx_entry = lookup->dl_dx_entry;
+        struct ocfs2_dir_block_trailer *trailer;
         struct ocfs2_dx_root_block *dx_root;
         struct ocfs2_dx_entry_list *entry_list;
 
+        /*
+         * This function gets a bit messy because we might have to
+         * modify the root block, regardless of whether the indexed
+         * entries are stored inline.
+         */
+
+        /*
+         * *Only* set 'entry_list' here, based on where we're looking
+         * for the indexed entries. Later, we might still want to
+         * journal both blocks, based on free list state.
+         */
         dx_root = (struct ocfs2_dx_root_block *)dx_root_bh->b_data;
         if (ocfs2_dx_root_inline(dx_root)) {
                 entry_list = &dx_root->dr_entries;
@@ -1203,6 +1307,15 @@ static int ocfs2_delete_entry_dx(handle_t *handle, struct inode *dir,
         }
 
         /*
+         * We know that removal of this dirent will leave enough room
+         * for a new one, so add this block to the free list if it
+         * isn't already there.
+         */
+        trailer = ocfs2_trailer_from_bh(leaf_bh, dir->i_sb);
+        if (trailer->db_free_rec_len == 0)
+                add_to_free_list = 1;
+
+        /*
          * Add the block holding our index into the journal before
          * removing the unindexed entry. If we get an error return
          * from __ocfs2_delete_entry(), then it hasn't removed the
@@ -1212,14 +1325,16 @@ static int ocfs2_delete_entry_dx(handle_t *handle, struct inode *dir,
          * We're also careful to journal the root tree block here if
          * we're going to be adding to the start of the free list.
          */
-        if (ocfs2_dx_root_inline(dx_root)) {
+        if (add_to_free_list || ocfs2_dx_root_inline(dx_root)) {
                 ret = ocfs2_journal_access_dr(handle, dir, dx_root_bh,
                                               OCFS2_JOURNAL_ACCESS_WRITE);
                 if (ret) {
                         mlog_errno(ret);
                         goto out;
                 }
-        } else {
+        }
+
+        if (!ocfs2_dx_root_inline(dx_root)) {
                 ret = ocfs2_journal_access_dl(handle, dir,
                                               lookup->dl_dx_leaf_bh,
                                               OCFS2_JOURNAL_ACCESS_WRITE);
@@ -1239,6 +1354,17 @@ static int ocfs2_delete_entry_dx(handle_t *handle, struct inode *dir,
                 goto out;
         }
 
+        max_rec_len = ocfs2_find_max_rec_len(dir->i_sb, leaf_bh);
+        trailer->db_free_rec_len = cpu_to_le16(max_rec_len);
+        if (add_to_free_list) {
+                trailer->db_free_next = dx_root->dr_free_blk;
+                dx_root->dr_free_blk = cpu_to_le64(leaf_bh->b_blocknr);
+                ocfs2_journal_dirty(handle, dx_root_bh);
+        }
+
+        /* leaf_bh was journal_accessed for us in __ocfs2_delete_entry */
+        ocfs2_journal_dirty(handle, leaf_bh);
+
         ocfs2_dx_list_remove_entry(entry_list, index);
 
         if (ocfs2_dx_root_inline(dx_root))
@@ -1422,6 +1548,59 @@ static int ocfs2_dx_dir_insert(struct inode *dir, handle_t *handle,
                                           lookup->dl_dx_leaf_bh);
 }
 
+static void ocfs2_remove_block_from_free_list(struct inode *dir,
+                                       handle_t *handle,
+                                       struct ocfs2_dir_lookup_result *lookup)
+{
+        struct ocfs2_dir_block_trailer *trailer, *prev;
+        struct ocfs2_dx_root_block *dx_root;
+        struct buffer_head *bh;
+
+        trailer = ocfs2_trailer_from_bh(lookup->dl_leaf_bh, dir->i_sb);
+
+        if (ocfs2_free_list_at_root(lookup)) {
+                bh = lookup->dl_dx_root_bh;
+                dx_root = (struct ocfs2_dx_root_block *)bh->b_data;
+                dx_root->dr_free_blk = trailer->db_free_next;
+        } else {
+                bh = lookup->dl_prev_leaf_bh;
+                prev = ocfs2_trailer_from_bh(bh, dir->i_sb);
+                prev->db_free_next = trailer->db_free_next;
+        }
+
+        trailer->db_free_rec_len = cpu_to_le16(0);
+        trailer->db_free_next = cpu_to_le64(0);
+
+        ocfs2_journal_dirty(handle, bh);
+        ocfs2_journal_dirty(handle, lookup->dl_leaf_bh);
+}
+
+/*
+ * This expects that a journal write has been reserved on
+ * lookup->dl_prev_leaf_bh or lookup->dl_dx_root_bh
+ */
+static void ocfs2_recalc_free_list(struct inode *dir, handle_t *handle,
+                                   struct ocfs2_dir_lookup_result *lookup)
+{
+        int max_rec_len;
+        struct ocfs2_dir_block_trailer *trailer;
+
+        /* Walk dl_leaf_bh to figure out what the new free rec_len is. */
+        max_rec_len = ocfs2_find_max_rec_len(dir->i_sb, lookup->dl_leaf_bh);
+        if (max_rec_len) {
+                /*
+                 * There's still room in this block, so no need to remove it
+                 * from the free list. In this case, we just want to update
+                 * the rec len accounting.
+                 */
+                trailer = ocfs2_trailer_from_bh(lookup->dl_leaf_bh, dir->i_sb);
+                trailer->db_free_rec_len = cpu_to_le16(max_rec_len);
+                ocfs2_journal_dirty(handle, lookup->dl_leaf_bh);
+        } else {
+                ocfs2_remove_block_from_free_list(dir, handle, lookup);
+        }
+}
+
 /* we don't always have a dentry for what we want to add, so people
  * like orphan dir can call this instead.
  *
@@ -1450,7 +1629,31 @@ int __ocfs2_add_entry(handle_t *handle,
         if (!namelen)
                 return -EINVAL;
 
-        if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
+        if (ocfs2_dir_indexed(dir)) {
+                struct buffer_head *bh;
+
+                /*
+                 * An indexed dir may require that we update the free space
+                 * list. Reserve a write to the previous node in the list so
+                 * that we don't fail later.
+                 *
+                 * XXX: This can be either a dx_root_block, or an unindexed
+                 * directory tree leaf block.
+                 */
+                if (ocfs2_free_list_at_root(lookup)) {
+                        bh = lookup->dl_dx_root_bh;
+                        retval = ocfs2_journal_access_dr(handle, dir, bh,
+                                                 OCFS2_JOURNAL_ACCESS_WRITE);
+                } else {
+                        bh = lookup->dl_prev_leaf_bh;
+                        retval = ocfs2_journal_access_db(handle, dir, bh,
+                                                 OCFS2_JOURNAL_ACCESS_WRITE);
+                }
+                if (retval) {
+                        mlog_errno(retval);
+                        return retval;
+                }
+        } else if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
                 data_start = di->id2.i_data.id_data;
                 size = i_size_read(dir);
 
@@ -1533,6 +1736,9 @@ int __ocfs2_add_entry(handle_t *handle,
                         de->name_len = namelen;
                         memcpy(de->name, name, namelen);
 
+                        if (ocfs2_dir_indexed(dir))
+                                ocfs2_recalc_free_list(dir, handle, lookup);
+
                         dir->i_version++;
                         status = ocfs2_journal_dirty(handle, insert_bh);
                         retval = 0;
@@ -2056,7 +2262,7 @@ static int ocfs2_fill_new_dir_el(struct ocfs2_super *osb,
 
         mlog_entry_void();
 
-        if (ocfs2_supports_dir_trailer(osb))
+        if (ocfs2_new_dir_wants_trailer(inode))
                 size = ocfs2_dir_trailer_blk_off(parent->i_sb);
 
         status = ocfs2_do_extend_dir(osb->sb, handle, inode, fe_bh,
@@ -2077,8 +2283,19 @@ static int ocfs2_fill_new_dir_el(struct ocfs2_super *osb,
         memset(new_bh->b_data, 0, osb->sb->s_blocksize);
 
         de = ocfs2_fill_initial_dirents(inode, parent, new_bh->b_data, size);
-        if (ocfs2_supports_dir_trailer(osb))
-                ocfs2_init_dir_trailer(inode, new_bh);
+        if (ocfs2_new_dir_wants_trailer(inode)) {
+                int size = le16_to_cpu(de->rec_len);
+
+                /*
+                 * Figure out the size of the hole left over after
+                 * insertion of '.' and '..'. The trailer wants this
+                 * information.
+                 */
+                size -= OCFS2_DIR_REC_LEN(2);
+                size -= sizeof(struct ocfs2_dir_block_trailer);
+
+                ocfs2_init_dir_trailer(inode, new_bh, size);
+        }
 
         status = ocfs2_journal_dirty(handle, new_bh);
         if (status < 0) {
@@ -2110,6 +2327,7 @@ bail:
 static int ocfs2_dx_dir_attach_index(struct ocfs2_super *osb,
                                      handle_t *handle, struct inode *dir,
                                      struct buffer_head *di_bh,
+                                     struct buffer_head *dirdata_bh,
                                      struct ocfs2_alloc_context *meta_ac,
                                      int dx_inline,
                                      struct buffer_head **ret_dx_root_bh)
@@ -2121,6 +2339,8 @@ static int ocfs2_dx_dir_attach_index(struct ocfs2_super *osb,
         unsigned int num_bits;
         struct buffer_head *dx_root_bh = NULL;
         struct ocfs2_dx_root_block *dx_root;
+        struct ocfs2_dir_block_trailer *trailer =
+                ocfs2_trailer_from_bh(dirdata_bh, dir->i_sb);
 
         ret = ocfs2_claim_metadata(osb, handle, meta_ac, 1, &dr_suballoc_bit,
                                    &num_bits, &dr_blkno);
@@ -2155,6 +2375,10 @@ static int ocfs2_dx_dir_attach_index(struct ocfs2_super *osb,
         dx_root->dr_fs_generation = cpu_to_le32(osb->fs_generation);
         dx_root->dr_blkno = cpu_to_le64(dr_blkno);
         dx_root->dr_dir_blkno = cpu_to_le64(OCFS2_I(dir)->ip_blkno);
+        if (le16_to_cpu(trailer->db_free_rec_len))
+                dx_root->dr_free_blk = cpu_to_le64(dirdata_bh->b_blocknr);
+        else
+                dx_root->dr_free_blk = cpu_to_le64(0);
 
         if (dx_inline) {
                 dx_root->dr_flags |= OCFS2_DX_FLAG_INLINE;
@@ -2361,7 +2585,7 @@ static int ocfs2_fill_new_dir_dx(struct ocfs2_super *osb,
                 goto out;
         }
 
-        ret = ocfs2_dx_dir_attach_index(osb, handle, inode, di_bh,
+        ret = ocfs2_dx_dir_attach_index(osb, handle, inode, di_bh, leaf_bh,
                                         meta_ac, 1, &dx_root_bh);
         if (ret) {
                 mlog_errno(ret);
@@ -2371,6 +2595,7 @@ static int ocfs2_fill_new_dir_dx(struct ocfs2_super *osb,
         entry_list = &dx_root->dr_entries;
 
         /* Buffer has been journaled for us by ocfs2_dx_dir_attach_index */
+        ocfs2_dx_dir_name_hash(inode, ".", 1, &hinfo);
         ocfs2_dx_entry_list_insert(entry_list, &hinfo, leaf_bh->b_blocknr);
 
         ocfs2_dx_dir_name_hash(inode, "..", 2, &hinfo);
@@ -2446,7 +2671,8 @@ inc:
 out:
         return ret;
 }
- /*
+
+/*
  * XXX: This expects dx_root_bh to already be part of the transaction.
  */
 static void ocfs2_dx_dir_index_root_block(struct inode *dir,
@@ -2521,18 +2747,26 @@ static int ocfs2_new_dx_should_be_inline(struct inode *dir,
  * expansion from an inline directory to one with extents. The first dir block
  * in that case is taken from the inline data portion of the inode block.
  *
+ * This will also return the largest amount of contiguous space for a dirent
+ * in the block. That value is *not* necessarily the last dirent, even after
+ * expansion. The directory indexing code wants this value for free space
+ * accounting. We do this here since we're already walking the entire dir
+ * block.
+ *
  * We add the dir trailer if this filesystem wants it.
  */
-static void ocfs2_expand_last_dirent(char *start, unsigned int old_size,
-                                     struct super_block *sb)
+static unsigned int ocfs2_expand_last_dirent(char *start, unsigned int old_size,
+                                             struct inode *dir)
 {
+        struct super_block *sb = dir->i_sb;
         struct ocfs2_dir_entry *de;
         struct ocfs2_dir_entry *prev_de;
         char *de_buf, *limit;
         unsigned int new_size = sb->s_blocksize;
-        unsigned int bytes;
+        unsigned int bytes, this_hole;
+        unsigned int largest_hole = 0;
 
-        if (ocfs2_supports_dir_trailer(OCFS2_SB(sb)))
+        if (ocfs2_new_dir_wants_trailer(dir))
                 new_size = ocfs2_dir_trailer_blk_off(sb);
 
         bytes = new_size - old_size;
@@ -2541,12 +2775,26 @@ static void ocfs2_expand_last_dirent(char *start, unsigned int old_size,
         de_buf = start;
         de = (struct ocfs2_dir_entry *)de_buf;
         do {
+                this_hole = ocfs2_figure_dirent_hole(de);
+                if (this_hole > largest_hole)
+                        largest_hole = this_hole;
+
                 prev_de = de;
                 de_buf += le16_to_cpu(de->rec_len);
                 de = (struct ocfs2_dir_entry *)de_buf;
         } while (de_buf < limit);
 
         le16_add_cpu(&prev_de->rec_len, bytes);
+
+        /* We need to double check this after modification of the final
+         * dirent. */
+        this_hole = ocfs2_figure_dirent_hole(prev_de);
+        if (this_hole > largest_hole)
+                largest_hole = this_hole;
+
+        if (largest_hole >= OCFS2_DIR_MIN_REC_LEN)
+                return largest_hole;
+        return 0;
 }
 
 /*
@@ -2703,9 +2951,16 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
         memcpy(dirdata_bh->b_data, di->id2.i_data.id_data, i_size_read(dir));
         memset(dirdata_bh->b_data + i_size_read(dir), 0,
                sb->s_blocksize - i_size_read(dir));
-        ocfs2_expand_last_dirent(dirdata_bh->b_data, i_size_read(dir), sb);
-        if (ocfs2_supports_dir_trailer(osb))
-                ocfs2_init_dir_trailer(dir, dirdata_bh);
+        i = ocfs2_expand_last_dirent(dirdata_bh->b_data, i_size_read(dir), dir);
+        if (ocfs2_new_dir_wants_trailer(dir)) {
+                /*
+                 * Prepare the dir trailer up front. It will otherwise look
+                 * like a valid dirent. Even if inserting the index fails
+                 * (unlikely), then all we'll have done is given first dir
+                 * block a small amount of fragmentation.
+                 */
+                ocfs2_init_dir_trailer(dir, dirdata_bh, i);
+        }
 
         ret = ocfs2_journal_dirty(handle, dirdata_bh);
         if (ret) {
@@ -2781,7 +3036,7 @@ static int ocfs2_expand_inline_dir(struct inode *dir, struct buffer_head *di_bh,
 
         if (ocfs2_supports_indexed_dirs(osb)) {
                 ret = ocfs2_dx_dir_attach_index(osb, handle, dir, di_bh,
-                                                meta_ac, dx_inline,
+                                                dirdata_bh, meta_ac, dx_inline,
                                                 &dx_root_bh);
                 if (ret) {
                         mlog_errno(ret);
@@ -2933,6 +3188,8 @@ bail:
  * is to be turned into an extent based one. The size of the dirent to
  * insert might be larger than the space gained by growing to just one
  * block, so we may have to grow the inode by two blocks in that case.
+ *
+ * If the directory is already indexed, dx_root_bh must be provided.
  */
 static int ocfs2_extend_dir(struct ocfs2_super *osb,
                             struct inode *dir,
@@ -2953,10 +3210,17 @@ static int ocfs2_extend_dir(struct ocfs2_super *osb,
         struct ocfs2_dir_entry * de;
         struct super_block *sb = osb->sb;
         struct ocfs2_extent_tree et;
+        struct buffer_head *dx_root_bh = lookup->dl_dx_root_bh;
 
         mlog_entry_void();
 
         if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
+                /*
+                 * This would be a code error as an inline directory should
+                 * never have an index root.
+                 */
+                BUG_ON(dx_root_bh);
+
                 status = ocfs2_expand_inline_dir(dir, parent_fe_bh,
                                                  blocks_wanted, lookup,
                                                  &new_bh);
@@ -2965,6 +3229,10 @@ static int ocfs2_extend_dir(struct ocfs2_super *osb,
                         goto bail;
                 }
 
+                /* Expansion from inline to an indexed directory will
+                 * have given us this. */
+                dx_root_bh = lookup->dl_dx_root_bh;
+
                 if (blocks_wanted == 1) {
                         /*
                          * If the new dirent will fit inside the space
@@ -3028,6 +3296,10 @@ static int ocfs2_extend_dir(struct ocfs2_super *osb,
         }
 
 do_extend:
+        if (ocfs2_dir_indexed(dir))
+                credits++; /* For attaching the new dirent block to the
+                            * dx_root */
+
         down_write(&OCFS2_I(dir)->ip_alloc_sem);
         drop_alloc_sem = 1;
 
@@ -3058,9 +3330,19 @@ do_extend:
 
         de = (struct ocfs2_dir_entry *) new_bh->b_data;
         de->inode = 0;
-        if (ocfs2_dir_has_trailer(dir)) {
+        if (ocfs2_supports_dir_trailer(dir)) {
                 de->rec_len = cpu_to_le16(ocfs2_dir_trailer_blk_off(sb));
-                ocfs2_init_dir_trailer(dir, new_bh);
+
+                ocfs2_init_dir_trailer(dir, new_bh, le16_to_cpu(de->rec_len));
+
+                if (ocfs2_dir_indexed(dir)) {
+                        status = ocfs2_dx_dir_link_trailer(dir, handle,
+                                                           dx_root_bh, new_bh);
+                        if (status) {
+                                mlog_errno(status);
+                                goto bail;
+                        }
+                }
         } else {
                 de->rec_len = cpu_to_le16(sb->s_blocksize);
         }
@@ -3116,7 +3398,7 @@ static int ocfs2_find_dir_space_id(struct inode *dir, struct buffer_head *di_bh,
          * This calculates how many free bytes we'd have in block zero, should
          * this function force expansion to an extent tree.
          */
-        if (ocfs2_supports_dir_trailer(OCFS2_SB(sb)))
+        if (ocfs2_new_dir_wants_trailer(dir))
                 free_space = ocfs2_dir_trailer_blk_off(sb) - i_size_read(dir);
         else
                 free_space = dir->i_sb->s_blocksize - i_size_read(dir);
@@ -3647,6 +3929,127 @@ out:
         return ret;
 }
 
+static int ocfs2_find_dir_space_dx(struct ocfs2_super *osb, struct inode *dir,
+                                   struct buffer_head *di_bh,
+                                   struct buffer_head *dx_root_bh,
+                                   const char *name, int namelen,
+                                   struct ocfs2_dir_lookup_result *lookup)
+{
+        int ret, rebalanced = 0;
+        struct ocfs2_dx_root_block *dx_root;
+        struct buffer_head *dx_leaf_bh = NULL;
+        struct ocfs2_dx_leaf *dx_leaf;
+        u64 blkno;
+        u32 leaf_cpos;
+
+        dx_root = (struct ocfs2_dx_root_block *)dx_root_bh->b_data;
+
+restart_search:
+        ret = ocfs2_dx_dir_lookup(dir, &dx_root->dr_list, &lookup->dl_hinfo,
+                                  &leaf_cpos, &blkno);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_read_dx_leaf(dir, blkno, &dx_leaf_bh);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        dx_leaf = (struct ocfs2_dx_leaf *)dx_leaf_bh->b_data;
+
+        if (le16_to_cpu(dx_leaf->dl_list.de_num_used) >=
+            le16_to_cpu(dx_leaf->dl_list.de_count)) {
+                if (rebalanced) {
+                        /*
+                         * Rebalancing should have provided us with
+                         * space in an appropriate leaf.
+                         *
+                         * XXX: Is this an abnormal condition then?
+                         * Should we print a message here?
+                         */
+                        ret = -ENOSPC;
+                        goto out;
+                }
+
+                ret = ocfs2_dx_dir_rebalance(osb, dir, dx_root_bh, dx_leaf_bh,
+                                             &lookup->dl_hinfo, leaf_cpos,
+                                             blkno);
+                if (ret) {
+                        if (ret != -ENOSPC)
+                                mlog_errno(ret);
+                        goto out;
+                }
+
+                /*
+                 * Restart the lookup. The rebalance might have
+                 * changed which block our item fits into. Mark our
+                 * progress, so we only execute this once.
+                 */
+                brelse(dx_leaf_bh);
+                dx_leaf_bh = NULL;
+                rebalanced = 1;
+                goto restart_search;
+        }
+
+        lookup->dl_dx_leaf_bh = dx_leaf_bh;
+        dx_leaf_bh = NULL;
+
+out:
+        brelse(dx_leaf_bh);
+        return ret;
+}
+
+static int ocfs2_search_dx_free_list(struct inode *dir,
+                                     struct buffer_head *dx_root_bh,
+                                     int namelen,
+                                     struct ocfs2_dir_lookup_result *lookup)
+{
+        int ret = -ENOSPC;
+        struct buffer_head *leaf_bh = NULL, *prev_leaf_bh = NULL;
+        struct ocfs2_dir_block_trailer *db;
+        u64 next_block;
+        int rec_len = OCFS2_DIR_REC_LEN(namelen);
+        struct ocfs2_dx_root_block *dx_root;
+
+        dx_root = (struct ocfs2_dx_root_block *)dx_root_bh->b_data;
+        next_block = le64_to_cpu(dx_root->dr_free_blk);
+
+        while (next_block) {
+                brelse(prev_leaf_bh);
+                prev_leaf_bh = leaf_bh;
+                leaf_bh = NULL;
+
+                ret = ocfs2_read_dir_block_direct(dir, next_block, &leaf_bh);
+                if (ret) {
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                db = ocfs2_trailer_from_bh(leaf_bh, dir->i_sb);
+                if (rec_len <= le16_to_cpu(db->db_free_rec_len)) {
+                        lookup->dl_leaf_bh = leaf_bh;
+                        lookup->dl_prev_leaf_bh = prev_leaf_bh;
+                        leaf_bh = NULL;
+                        prev_leaf_bh = NULL;
+                        break;
+                }
+
+                next_block = le64_to_cpu(db->db_free_next);
+        }
+
+        if (!next_block)
+                ret = -ENOSPC;
+
+out:
+
+        brelse(leaf_bh);
+        brelse(prev_leaf_bh);
+        return ret;
+}
+
 static int ocfs2_expand_inline_dx_root(struct inode *dir,
                                        struct buffer_head *dx_root_bh)
 {
@@ -3779,19 +4182,18 @@ static int ocfs2_inline_dx_has_space(struct buffer_head *dx_root_bh)
         return 0;
 }
 
-static int ocfs2_find_dir_space_dx(struct ocfs2_super *osb, struct inode *dir,
-                                   struct buffer_head *di_bh, const char *name,
-                                   int namelen,
-                                   struct ocfs2_dir_lookup_result *lookup)
+static int ocfs2_prepare_dx_dir_for_insert(struct inode *dir,
+                                           struct buffer_head *di_bh,
+                                           const char *name,
+                                           int namelen,
+                                           struct ocfs2_dir_lookup_result *lookup)
 {
-        int ret, rebalanced = 0;
+        int ret, free_dx_root = 1;
+        struct ocfs2_super *osb = OCFS2_SB(dir->i_sb);
         struct buffer_head *dx_root_bh = NULL;
-        struct ocfs2_dx_root_block *dx_root;
-        struct buffer_head *dx_leaf_bh = NULL;
-        struct ocfs2_dx_leaf *dx_leaf;
+        struct buffer_head *leaf_bh = NULL;
         struct ocfs2_dinode *di = (struct ocfs2_dinode *)di_bh->b_data;
-        u64 blkno;
-        u32 leaf_cpos;
+        struct ocfs2_dx_root_block *dx_root;
 
         ret = ocfs2_read_dx_root(dir, di, &dx_root_bh);
         if (ret) {
@@ -3818,65 +4220,55 @@ static int ocfs2_find_dir_space_dx(struct ocfs2_super *osb, struct inode *dir,
                 }
         }
 
-restart_search:
-        ret = ocfs2_dx_dir_lookup(dir, &dx_root->dr_list, &lookup->dl_hinfo,
-                                  &leaf_cpos, &blkno);
+        /*
+         * Insert preparation for an indexed directory is split into two
+         * steps. The call to find_dir_space_dx reserves room in the index for
+         * an additional item. If we run out of space there, it's a real error
+         * we can't continue on.
+         */
+        ret = ocfs2_find_dir_space_dx(osb, dir, di_bh, dx_root_bh, name,
+                                      namelen, lookup);
         if (ret) {
                 mlog_errno(ret);
                 goto out;
         }
 
-        ret = ocfs2_read_dx_leaf(dir, blkno, &dx_leaf_bh);
-        if (ret) {
+search_el:
+        /*
+         * Next, we need to find space in the unindexed tree. This call
+         * searches using the free space linked list. If the unindexed tree
+         * lacks sufficient space, we'll expand it below. The expansion code
+         * is smart enough to add any new blocks to the free space list.
+         */
+        ret = ocfs2_search_dx_free_list(dir, dx_root_bh, namelen, lookup);
+        if (ret && ret != -ENOSPC) {
                 mlog_errno(ret);
                 goto out;
         }
 
-        dx_leaf = (struct ocfs2_dx_leaf *)dx_leaf_bh->b_data;
+        /* Do this up here - ocfs2_extend_dir might need the dx_root */
+        lookup->dl_dx_root_bh = dx_root_bh;
+        free_dx_root = 0;
 
-        if (le16_to_cpu(dx_leaf->dl_list.de_num_used) >=
-            le16_to_cpu(dx_leaf->dl_list.de_count)) {
-                if (rebalanced) {
-                        /*
-                         * Rebalancing should have provided us with
-                         * space in an appropriate leaf.
-                         *
-                         * XXX: Is this an abnormal condition then?
-                         * Should we print a message here?
-                         */
-                        ret = -ENOSPC;
-                        goto out;
-                }
+        if (ret == -ENOSPC) {
+                ret = ocfs2_extend_dir(osb, dir, di_bh, 1, lookup, &leaf_bh);
 
-                ret = ocfs2_dx_dir_rebalance(osb, dir, dx_root_bh, dx_leaf_bh,
-                                             &lookup->dl_hinfo, leaf_cpos,
-                                             blkno);
                 if (ret) {
-                        if (ret != -ENOSPC)
-                                mlog_errno(ret);
+                        mlog_errno(ret);
                         goto out;
                 }
 
                 /*
-                 * Restart the lookup. The rebalance might have
-                 * changed which block our item fits into. Mark our
-                 * progress, so we only execute this once.
+                 * We make the assumption here that new leaf blocks are added
+                 * to the front of our free list.
                  */
-                brelse(dx_leaf_bh);
-                dx_leaf_bh = NULL;
-                rebalanced = 1;
-                goto restart_search;
+                lookup->dl_prev_leaf_bh = NULL;
+                lookup->dl_leaf_bh = leaf_bh;
         }
 
-search_el:
-        lookup->dl_dx_leaf_bh = dx_leaf_bh;
-        dx_leaf_bh = NULL;
-        lookup->dl_dx_root_bh = dx_root_bh;
-        dx_root_bh = NULL;
-
 out:
-        brelse(dx_leaf_bh);
-        brelse(dx_root_bh);
+        if (free_dx_root)
+                brelse(dx_root_bh);
         return ret;
 }
 
@@ -3921,17 +4313,11 @@ int ocfs2_prepare_dir_for_insert(struct ocfs2_super *osb,
                 ocfs2_dx_dir_name_hash(dir, name, namelen, &lookup->dl_hinfo);
 
         if (ocfs2_dir_indexed(dir)) {
-                ret = ocfs2_find_dir_space_dx(osb, dir, parent_fe_bh, name,
-                                              namelen, lookup);
-                if (ret) {
+                ret = ocfs2_prepare_dx_dir_for_insert(dir, parent_fe_bh,
+                                                      name, namelen, lookup);
+                if (ret)
                         mlog_errno(ret);
-                        goto out;
-                }
-
-                /*
-                 * We intentionally fall through so that the unindexed
-                 * tree can also be prepared.
-                 */
+                goto out;
         }
 
         if (OCFS2_I(dir)->ip_dyn_features & OCFS2_INLINE_DATA_FL) {
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,
diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 5585dde91344..582e27e57f34 100644
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -385,8 +385,8 @@ static inline int ocfs2_remove_extent_credits(struct super_block *sb)
 }
 
 /* data block for new dir/symlink, 2 for bitmap updates (bitmap fe +
- * bitmap block for the new bit) */
-#define OCFS2_DIR_LINK_ADDITIONAL_CREDITS (1 + 2)
+ * bitmap block for the new bit) dx_root update for free list */
+#define OCFS2_DIR_LINK_ADDITIONAL_CREDITS (1 + 2 + 1)
 
 static inline int ocfs2_add_dir_index_credits(struct super_block *sb)
 {
@@ -420,19 +420,19 @@ static inline int ocfs2_mknod_credits(struct super_block *sb, int is_dir,
 #define OCFS2_SIMPLE_DIR_EXTEND_CREDITS (2)
 
 /* file update (nlink, etc) + directory mtime/ctime + dir entry block + quota
- * update on dir + index leaf */
+ * update on dir + index leaf + dx root update for free list */
 static inline int ocfs2_link_credits(struct super_block *sb)
 {
-        return 2*OCFS2_INODE_UPDATE_CREDITS + 2 +
+        return 2*OCFS2_INODE_UPDATE_CREDITS + 3 +
                ocfs2_quota_trans_credits(sb);
 }
 
 /* inode + dir inode (if we unlink a dir), + dir entry block + orphan
- * dir inode link + dir inode index leaf */
+ * dir inode link + dir inode index leaf + dir index root */
 static inline int ocfs2_unlink_credits(struct super_block *sb)
 {
         /* The quota update from ocfs2_link_credits is unused here... */
-        return 2 * OCFS2_INODE_UPDATE_CREDITS + 2 + ocfs2_link_credits(sb);
+        return 2 * OCFS2_INODE_UPDATE_CREDITS + 3 + ocfs2_link_credits(sb);
 }
 
 /* dinode + orphan dir dinode + inode alloc dinode + orphan dir entry +
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