During BKL removal in 2.6.38, conversion of files from in-ICB format to normal
format got broken. We call ->writepage with i_data_sem held but udf_get_block()
also acquires i_data_sem thus creating A-A deadlock.

We fix the problem by dropping i_data_sem before calling ->writepage() which is
safe since i_mutex still protects us against any changes in the file. Also fix
pagelock - i_data_sem lock inversion in udf_expand_file_adinicb() by dropping
i_data_sem before calling find_or_create_page().

CC: stable@kernel.org
Reported-by: NMatthias Matiak <netzpython@mail-on.us>
Tested-by: NMatthias Matiak <netzpython@mail-on.us>
Reviewed-by: NNamjae Jeon <linkinjeon@gmail.com>
Signed-off-by: NJan Kara <jack@suse.cz>