loop: add ioctl for changing logical block size
This is a different approach from the first attempt in f2c6df7dbf9a
("loop: support 4k physical blocksize"). Rather than extending
LOOP_{GET,SET}_STATUS, add a separate ioctl just for setting the block
size.
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index e3f1900..ac106b2 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1047,6 +1047,7 @@
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 @@
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 @@
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;
}