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Commit 89e4fdec authored by Omar Sandoval's avatar Omar Sandoval Committed by Jens Axboe
Browse files

loop: add ioctl for changing logical block size 



This is a different approach from the first attempt in f2c6df7d
("loop: support 4k physical blocksize"). Rather than extending
LOOP_{GET,SET}_STATUS, add a separate ioctl just for setting the block
size.

Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
Signed-off-by: default avatarOmar Sandoval <osandov@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 6c6b6f28

drivers/block/loop.c

+24 −0
Original line number Diff line number Diff line
@@ -1047,6 +1047,7 @@ static int loop_clr_fd(struct loop_device *lo) 
	memset(lo->lo_encrypt_key, 0, LO_KEY_SIZE);

	memset(lo->lo_crypt_name, 0, LO_NAME_SIZE);

	memset(lo->lo_file_name, 0, LO_NAME_SIZE);

	blk_queue_logical_block_size(lo->lo_queue, 512);

	if (bdev) {

		bdput(bdev);

		invalidate_bdev(bdev);
@@ -1330,6 +1331,24 @@ static int loop_set_dio(struct loop_device *lo, unsigned long arg) 
	return error;

}



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

{

	if (lo->lo_state != Lo_bound)

		return -ENXIO;



	if (arg < 512 || arg > PAGE_SIZE || !is_power_of_2(arg))

		return -EINVAL;



	blk_mq_freeze_queue(lo->lo_queue);



	blk_queue_logical_block_size(lo->lo_queue, arg);

	loop_update_dio(lo);



	blk_mq_unfreeze_queue(lo->lo_queue);



	return 0;

}



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

	unsigned int cmd, unsigned long arg)

{
@@ -1378,6 +1397,11 @@ static int lo_ioctl(struct block_device *bdev, fmode_t mode, 
		if ((mode & FMODE_WRITE) || capable(CAP_SYS_ADMIN))

			err = loop_set_dio(lo, arg);

		break;

	case LOOP_SET_BLOCK_SIZE:

		err = -EPERM;

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

			err = loop_set_block_size(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
@@ -88,6 +88,7 @@ struct loop_info64 { 
#define LOOP_CHANGE_FD		0x4C06

#define LOOP_SET_CAPACITY	0x4C07

#define LOOP_SET_DIRECT_IO	0x4C08

#define LOOP_SET_BLOCK_SIZE	0x4C09



/* /dev/loop-control interface */

#define LOOP_CTL_ADD		0x4C80