This forces the bch layer to read the sector from the physical device
instead of using the cached values. It is necessary to call when the
device is updated from the different source than bch, for example
erased by the MTD ioctl command.
It also has to invalidate readahead buffer from FTL if option
CONFIG_DRVR_READAHEAD is set.
Signed-off-by: Michal Lenc <michallenc@seznam.cz>
d9270f9ea8