Re: [PATCH 4.4 4.9 4.14] loop: Add LOOP_SET_DIRECT_IO to compat ioctl

From: Sasha Levin
Date: Thu Oct 24 2019 - 20:18:09 EST

On Wed, Oct 23, 2019 at 06:17:36PM +0100, Alessio Balsini wrote:
[ 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

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@xxxxxxxxx>
Signed-off-by: Alessio Balsini <balsini@xxxxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

Queued up, thanks!