Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ab1cb278 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: loop: introduce ioctl command of LOOP_SET_DIRECT_IO 



If loop block is mounted via 'mount -o loop', it isn't easy
to pass file descriptor opened as O_DIRECT, so this patch
introduces a new command to support direct IO for this case.

Cc: linux-api@vger.kernel.org
Signed-off-by: default avatarMing Lei <ming.lei@canonical.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent 2e5ab5f3

drivers/block/loop.c

+19 −0
Original line number Diff line number Diff line
@@ -1228,6 +1228,20 @@ static int loop_set_capacity(struct loop_device *lo, struct block_device *bdev) 
	return figure_loop_size(lo, lo->lo_offset, lo->lo_sizelimit);

}



static int loop_set_dio(struct loop_device *lo, unsigned long arg)

{

	int error = -ENXIO;

	if (lo->lo_state != Lo_bound)

		goto out;



	__loop_update_dio(lo, !!arg);

	if (lo->use_dio == !!arg)

		return 0;

	error = -EINVAL;

 out:

	return error;

}



static int lo_ioctl(struct block_device *bdev, fmode_t mode,

	unsigned int cmd, unsigned long arg)

{
@@ -1271,6 +1285,11 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, 
		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))

			err = loop_set_capacity(lo, bdev);

		break;

	case LOOP_SET_DIRECT_IO:

		err = -EPERM;

		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))

			err = loop_set_dio(lo, arg);

		break;

	default:

		err = lo->ioctl ? lo->ioctl(lo, cmd, arg) : -EINVAL;

	}

include/uapi/linux/loop.h

+1 −0
Original line number Diff line number Diff line
@@ -87,6 +87,7 @@ struct loop_info64 { 
#define LOOP_GET_STATUS64	0x4C05

#define LOOP_CHANGE_FD		0x4C06

#define LOOP_SET_CAPACITY	0x4C07

#define LOOP_SET_DIRECT_IO	0x4C08



/* /dev/loop-control interface */

#define LOOP_CTL_ADD		0x4C80