ocfs2: __ocfs2_mknod_locked should return error when ocfs2_create_new_inode_locks...

ocfs2: __ocfs2_mknod_locked should return error when ocfs2_create_new_inode_locks() failed

When ocfs2_create_new_inode_locks() return error, inode open lock may
not be obtainted for this inode.  So other nodes can remove this file
and free dinode when inode still remain in memory on this node, which is
not correct and may trigger BUG.  So __ocfs2_mknod_locked should return
error when ocfs2_create_new_inode_locks() failed.

              Node_1                              Node_2
create fileA, call ocfs2_mknod()
  -> ocfs2_get_init_inode(), allocate inodeA
  -> ocfs2_claim_new_inode(), claim dinode(dinodeA)
  -> call ocfs2_create_new_inode_locks(),
     create open lock failed, return error
  -> __ocfs2_mknod_locked return success

                                                unlink fileA
                                                try open lock succeed,
                                                and free dinodeA

create another file, call ocfs2_mknod()
  -> ocfs2_get_init_inode(), allocate inodeB
  -> ocfs2_claim_new_inode(), as Node_2 had freed dinodeA,
     so claim dinodeA and update generation for dinodeA

call __ocfs2_drop_dl_inodes()->ocfs2_delete_inode()
to free inodeA, and finally triggers BUG
on(inode->i_generation != le32_to_cpu(fe->i_generation))
in function ocfs2_inode_lock_update().

Signed-off-by: joyce.xue <xuejiufei@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>