ext4: cleanup ext4_ext_grow_indepth code

Currently code make an impression what grow procedure is very complicated
and some mythical paths, blocks are involved. But in fact grow in depth
it relatively simple procedure:
 1) Just create new meta block and copy root data to that block.
 2) Convert root from extent to index if old depth == 0
 3) Update root block pointer

This patch does:
 - Reorganize code to make it more self explanatory
 - Do not pass path parameter to new_meta_block() in order to
   provoke allocation from inode's group because top-level block
   should site closer to it's inode, but not to leaf data block.

   [ This happens anyway, due to logic in mballoc; we should drop
     the path parameter from new_meta_block() entirely.  -- tytso ]

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 15 insertions, 26 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 2fc6cc0a51ca..385ebb435332 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -1050,16 +1050,14 @@ cleanup:
  */
 static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
                                  unsigned int flags,
-                                 struct ext4_ext_path *path,
                                  struct ext4_extent *newext)
 {
-        struct ext4_ext_path *curp = path;
         struct ext4_extent_header *neh;
         struct buffer_head *bh;
         ext4_fsblk_t newblock;
         int err = 0;
 
-        newblock = ext4_ext_new_meta_block(handle, inode, path,
+        newblock = ext4_ext_new_meta_block(handle, inode, NULL,
                 newext, &err, flags);
         if (newblock == 0)
                 return err;
@@ -1079,7 +1077,8 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
         }
 
         /* move top-level index/leaf into new block */
-        memmove(bh->b_data, curp->p_hdr, sizeof(EXT4_I(inode)->i_data));
+        memmove(bh->b_data, EXT4_I(inode)->i_data,
+                sizeof(EXT4_I(inode)->i_data));
 
         /* set size of new block */
         neh = ext_block_hdr(bh);
@@ -1097,32 +1096,23 @@ static int ext4_ext_grow_indepth(handle_t *handle, struct inode *inode,
         if (err)
                 goto out;
 
-        /* create index in new top-level index: num,max,pointer */
-        err = ext4_ext_get_access(handle, inode, curp);
-        if (err)
-                goto out;
-
-        curp->p_hdr->eh_magic = EXT4_EXT_MAGIC;
-        curp->p_hdr->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
-        curp->p_hdr->eh_entries = cpu_to_le16(1);
-        curp->p_idx = EXT_FIRST_INDEX(curp->p_hdr);
-
-        if (path[0].p_hdr->eh_depth)
-                curp->p_idx->ei_block =
-                        EXT_FIRST_INDEX(path[0].p_hdr)->ei_block;
-        else
-                curp->p_idx->ei_block =
-                        EXT_FIRST_EXTENT(path[0].p_hdr)->ee_block;
-        ext4_idx_store_pblock(curp->p_idx, newblock);
-
+        /* Update top-level index: num,max,pointer */
         neh = ext_inode_hdr(inode);
+        neh->eh_entries = cpu_to_le16(1);
+        ext4_idx_store_pblock(EXT_FIRST_INDEX(neh), newblock);
+        if (neh->eh_depth == 0) {
+                /* Root extent block becomes index block */
+                neh->eh_max = cpu_to_le16(ext4_ext_space_root_idx(inode, 0));
+                EXT_FIRST_INDEX(neh)->ei_block =
+                        EXT_FIRST_EXTENT(neh)->ee_block;
+        }
         ext_debug("new root: num %d(%d), lblock %d, ptr %llu\n",
                   le16_to_cpu(neh->eh_entries), le16_to_cpu(neh->eh_max),
                   le32_to_cpu(EXT_FIRST_INDEX(neh)->ei_block),
                   ext4_idx_pblock(EXT_FIRST_INDEX(neh)));
 
-        neh->eh_depth = cpu_to_le16(path->p_depth + 1);
-        err = ext4_ext_dirty(handle, inode, curp);
+        neh->eh_depth = cpu_to_le16(neh->eh_depth + 1);
+        ext4_mark_inode_dirty(handle, inode);
 out:
         brelse(bh);
 
@@ -1170,8 +1160,7 @@ repeat:
                         err = PTR_ERR(path);
         } else {
                 /* tree is full, time to grow in depth */
-                err = ext4_ext_grow_indepth(handle, inode, flags,
-                                            path, newext);
+                err = ext4_ext_grow_indepth(handle, inode, flags, newext);
                 if (err)
                         goto out;