direct-io: fix error-path crashes
direct-io: fix error-path crashes

Need to initialize map_bh.b_state to zero.  Otherwise, in case of a faulty
user-buffer its possible to go into dio_zero_block() and submit a page by
mistake - since it checks for buffer_new().

http://marc.info/?l=linux-kernel&m=118551339032528&w=2

akpm: Linus had a (better) patch to just do a kzalloc() in there, but it got
lost.  Probably this version is better for -stable anwyay.

Signed-off-by: Badari Pulavarty <a0471031ec5071754e15184cabeebf7217ef1fd9@us.ibm.com>
Acked-by: Joe Jin <f057b23ea7478423ae110c031964105cfff9b6e7@oracle.com>
Acked-by: Zach Brown <bdd5f2a410e3c75a25da3e38f76d719a18e93cd3@oracle.com>
Cc: gurudas pai <c21c0d03bc493950488c92eda4a45c164c2ba956@oracle.com>
Cc: <4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@kernel.org>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas