Re: + loop-preallocate-eight-loop-devices.patch added to -mm tree

From: Al Viro
Date: Mon May 21 2007 - 20:19:01 EST


On Mon, May 21, 2007 at 03:00:55PM -0700, akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> + if (register_blkdev(LOOP_MAJOR, "loop"))
> + return -EIO;
> + blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
> + THIS_MODULE, loop_probe, NULL, NULL);
> +
> + for (i = 0; i < nr; i++) {
> + if (!loop_init_one(i))
> + goto err;
> + }
> +
> + printk(KERN_INFO "loop: module loaded\n");
> + return 0;
> +err:
> + loop_exit();

This isn't good. You *can't* fail once a single disk has been registered.
Anyone could've opened it by now.

IOW, you need to
* register region *after* you are past the point of no return
* either not fail on failing loop_init_one() here, or separate
allocations and actual add_disk().
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