Date: Thu, 24 May 2012 13:46:49 -0400
From: Vivek Goyal <vgoyal@redhat.com>
To: Kent Overstreet <koverstreet@google.com>
Cc: linux-kernel@vger.kernel.org, linux-bcache@vger.kernel.org,
        dm-devel@redhat.com, linux-fsdevel@vger.kernel.org, tj@kernel.org,
        axboe@kernel.dk, agk@redhat.com, neilb@suse.de,
        drbd-dev@lists.linbit.com, bharrosh@panasas.com, mpatocka@redhat.com,
        sage@newdream.net, yehuda@hq.newdream.net
Subject: Re: [PATCH v2 01/14] block: Generalized bio pool freeing
Message-ID: <20120524174649.GC27550@redhat.com>
References: <1337817771-25038-1-git-send-email-koverstreet@google.com>
 <1337817771-25038-2-git-send-email-koverstreet@google.com>
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On Wed, May 23, 2012 at 05:02:38PM -0700, Kent Overstreet wrote:
> With the old code, when you allocate a bio from a bio pool you have to
> implement your own destructor that knows how to find the bio pool the
> bio was originally allocated from.
> 
> This adds a new field to struct bio (bi_pool) and changes
> bio_alloc_bioset() to use it. This makes various bio destructors
> unnecessary, so they're then deleted.
> 

[..]
> @@ -419,7 +406,11 @@ void bio_put(struct bio *bio)
>  	 */
>  	if (atomic_dec_and_test(&bio->bi_cnt)) {
>  		bio->bi_next = NULL;
> -		bio->bi_destructor(bio);
> +
> +		if (bio->bi_pool)
> +			bio_free(bio, bio->bi_pool);
> +		else
> +			bio->bi_destructor(bio);

If you have removed all the users of bi_destructor, then I am wondering that
why are we retaining this field and trying to call into it when bio_pool
is not set?

Thanks
Vivek

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