> @@ -441,6 +500,12 @@ static void do_loop_switch(struct loop_device *lo, > struct switch_request *p) > mapping->host->i_bdev->bd_block_size : PAGE_SIZE; > lo->old_gfp_mask = mapping_gfp_mask(mapping); > mapping_set_gfp_mask(mapping, lo->old_gfp_mask & ~(__GFP_IO|__GFP_FS)); > + > + lo->support_dio = mapping->a_ops && mapping->a_ops->direct_IO; > + if (lo->support_dio) > + lo->use_aio = true; > + else > + lo->use_aio = false;
We need an explicit userspace op-in for this. For one direct I/O can't handle sub-sector size access and people use the loop device as a workaround for that. Second this doesn't give anyone seeing negative results from aio a way to disable it easily. It think the best way is to require a setup time flag, but enable it to on in losetup versions that know about it. > @@ -761,6 +826,13 @@ static int loop_set_fd(struct loop_device *lo, fmode_t > mode, > if (!(lo_flags & LO_FLAGS_READ_ONLY) && file->f_op->fsync) > blk_queue_flush(lo->lo_queue, REQ_FLUSH); > > + /* use aio if it is possible */ > + lo->support_dio = mapping->a_ops && mapping->a_ops->direct_IO; > + if (lo->support_dio) > + lo->use_aio = true; > + else > + lo->use_aio = false; Please always factor out checks like this insted of duplicating them. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
