Hi! I got head revision of yaffs from git, an try to install it to 
3.14.4 kernel source (on 3.8.4 it was compiled successfull). Kernel 
compilation fails on yaffs_attributes.c, yaffs_vfs.c with errors.
Main reasons are:
1) struct iattr and struct inode no longer used uid_t and guid_t types, 
but kuid_t kguid_t instead.
2) proc filesystem changes fucntion set: no "create_proc_entry" 
function, but "proc_create_data" instead; additionally  
yaffs_proc_write, yaffs_proc_read must be
   adapted to struct file_operations wrte read prototypes.
3) struct file_operations no longer have readdir, but iterate instead, 
so yaffs_readdir must be adapted to different parameters list and 
work-logic.

I try to correct this errors byself, so kernel compiled successfull. 
Result - many oops and BUG on filesystem mount. It seems differences 
between core versions more complicated than
i suppose, and cant be corrected without yaffs developers team help. I 
also try to replace "adapted" functions with empty dummy code, but no 
success, same bugs appears. Please help me to adapt yaffs source on 
newest kernel versions!
Thanks!