There is memory leak as both caller function kmmpd() and callee
read_mmp_block() not releasing bh_check  (i.e buffer_head).
Given patch fixes this problem.

[ Additional changes suggested by Andreas Dilger -- TYT ]
Signed-off-by: NJadhav Vikram <vikramjadhavpucsd2007@gmail.com>
Signed-off-by: NTheodore Ts'o <tytso@mit.edu>