Re: [dm-devel] [PATCH] dm thin metadata: clarify __open_device functionality and fix callers

[Joe Thornber <thornber redhat com>]

On Mon, Jan 09, 2012 at 03:33:08PM -0500, Mike Snitzer wrote:
> The __open_device() error path of __create_thin() and __create_snap()
> will call __close_device() even if td was not initialized by
> __open_device().
>
> Clearly define what callers should expect from __open_device()'s
> return.
>
> Also, remove redundant 'td->changed = 1' in __create_thin() --
> __open_device() with create=1 will have set td->changed on successful
> return.

Hi Mike,

This looks like a code review patch, and as such I ACK it.

I don't think it changes any behaviour though.  Both create_thin and
create_snapshot hold a mutex when they run, and the first thing they
do is check for the existence of the device.

        r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
                            &key, &details_le);
        if (!r)
                return -EEXIST;

I don't think there's a race on creation?

We need to focus on reproducing Kabi's issue.

- Joe