f2fs: fix k3.0 merge by removing extra balance_fs and check

Change-Id: Icef3c6623a730d933071b7f600d758403fc64f16
fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers

Btrfs needs to be able to control how filemap_write_and_wait_range() is called
in fsync to make it less of a painful operation, so push down taking i_mutex and
the calling of filemap_write_and_wait() down into the ->fsync() handlers.  Some
file systems can drop taking the i_mutex altogether it seems, like ext3 and
ocfs2.  For correctness sake I just pushed everything down in all cases to make
sure that we keep the current behavior the same for everybody, and then each
individual fs maintainer can make up their mind about what to do from there.
Thanks,

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Conflicts:
	Documentation/filesystems/porting

Change-Id: I7697244cce355e6d443a39c5133a5c94f02e199b
f2fs: backport k3.0 re-add start/end params to f2fs_sync_file

Change-Id: I47df9dba3a37eae26d4d7bec9ed4700b14ea7f84
defconfig: otterx enable f2fs

Change-Id: I4cc836d67886968df890b0fca5110be0d892dbf2