From: Alessio Balsini balsini@android.com
[ Upstream commit fdbe4eeeb1aac219b14f10c0ed31ae5d1123e9b8 ]
Enabling Direct I/O with loop devices helps reducing memory usage by avoiding double caching. 32 bit applications running on 64 bits systems are currently not able to request direct I/O because is missing from the lo_compat_ioctl.
This patch fixes the compatibility issue mentioned above by exporting LOOP_SET_DIRECT_IO as additional lo_compat_ioctl() entry. The input argument for this ioctl is a single long converted to a 1-bit boolean, so compatibility is preserved.
Cc: Jens Axboe axboe@kernel.dk Signed-off-by: Alessio Balsini balsini@android.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/block/loop.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1557,6 +1557,7 @@ static int lo_compat_ioctl(struct block_ arg = (unsigned long) compat_ptr(arg); case LOOP_SET_FD: case LOOP_CHANGE_FD: + case LOOP_SET_DIRECT_IO: err = lo_ioctl(bdev, mode, cmd, arg); break; default: