From: Alex Tomas <bzzz@tmi.comex.ru>

ext3_get_inode_loc() read inode's block only if:

  1) this inode has no copy in memory
  2) inode's block has another valid inode(s)

this optimization allows to avoid needless I/O in two cases:

1) just allocated inode is first valid in the inode's block

2) kernel wants to write inode, but buffer in which inode
   belongs to gets freed by VM