From: Jeff Dike COWed devices can't handle more than 32 (64 on x86_64) sectors in one request due to the size of the bitmap being carried around in the io_thread_req. Enforce that by telling the block layer not to put too many sectors in requests to COWed devices. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- arch/um/drivers/ubd_kern.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -712,6 +712,8 @@ static int ubd_add(int n, char **error_o ubd_dev->queue->queuedata = ubd_dev; blk_queue_max_hw_segments(ubd_dev->queue, MAX_SG); + if(ubd_dev->cow.file != NULL) + blk_queue_max_sectors(ubd_dev->queue, 8 * sizeof(long)); err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]); if(err){ *error_out = "Failed to register device"; -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/