msync: fix incorrect fstart calculation
msync: fix incorrect fstart calculation

Fix a regression caused by 7fc34a62ca44 ("mm/msync.c: sync only the
requested range in msync()").

xfstests generic/075 fail occured on ext4 data=journal mode because the
intended range was not syncing due to wrong fstart calculation.

Signed-off-by: Namjae Jeon <65d484aa1efdaf0ae258f87a04ed8ec8685cba3e@samsung.com>
Signed-off-by: Ashish Sangwan <3e1f6bc3f57a77fb276e7ac9018adc534c863417@samsung.com>
Reported-by: Eric Whitney <ba5ac80d1fb5812604686391b77cc69908a724fa@gmail.com>
Tested-by: Eric Whitney <ba5ac80d1fb5812604686391b77cc69908a724fa@gmail.com>
Acked-by: Matthew Wilcox <ed1245e46949b7b8f2bca25d41520ebc8aeefcf8@intel.com>
Reviewed-by: Lukas Czerner <6c9141d0e2318b390a8a6bf8ecd9f819d16f05b4@redhat.com>
Tested-by: Lukas Czerner <6c9141d0e2318b390a8a6bf8ecd9f819d16f05b4@redhat.com>
Reviewed-by: Theodore Ts'o <4ed386e0495d3e109932df055831d9ec2f824927@mit.edu>
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,KristFoundation/Programs,KristFoundation/Programs