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Re: [dm-devel] [PATCH v5 04/12] pktcdvd: Switch to bio_kmalloc()



Hello,

On Mon, Aug 06, 2012 at 03:08:33PM -0700, Kent Overstreet wrote:
> This is prep work for killing bi_destructor - previously, pktcdvd had
> its own pkt_bio_alloc which was basically duplication bio_kmalloc(),
> necessitating its own bi_destructor implementation.
> 
> v5: Un-reorder some functions, to make the patch easier to review
> 
> Signed-off-by: Kent Overstreet <koverstreet google com>

Please Cc: the maintainers.  Cc'ing Peter Osterlund and keeping the
whole body for him.

Generally looks good to me.  How is this tested?

Thanks.

> ---
>  drivers/block/pktcdvd.c |   67 +++++++++++-----------------------------------
>  1 files changed, 16 insertions(+), 51 deletions(-)
> 
> diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
> index ba66e44..ae55f08 100644
> --- a/drivers/block/pktcdvd.c
> +++ b/drivers/block/pktcdvd.c
> @@ -101,6 +101,8 @@ static struct dentry	*pkt_debugfs_root = NULL; /* /sys/kernel/debug/pktcdvd */
>  static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev);
>  static int pkt_remove_dev(dev_t pkt_dev);
>  static int pkt_seq_show(struct seq_file *m, void *p);
> +static void pkt_end_io_read(struct bio *bio, int err);
> +static void pkt_end_io_packet_write(struct bio *bio, int err);
>  
>  
>  
> @@ -522,38 +524,6 @@ static void pkt_bio_finished(struct pktcdvd_device *pd)
>  	}
>  }
>  
> -static void pkt_bio_destructor(struct bio *bio)
> -{
> -	kfree(bio->bi_io_vec);
> -	kfree(bio);
> -}
> -
> -static struct bio *pkt_bio_alloc(int nr_iovecs)
> -{
> -	struct bio_vec *bvl = NULL;
> -	struct bio *bio;
> -
> -	bio = kmalloc(sizeof(struct bio), GFP_KERNEL);
> -	if (!bio)
> -		goto no_bio;
> -	bio_init(bio);
> -
> -	bvl = kcalloc(nr_iovecs, sizeof(struct bio_vec), GFP_KERNEL);
> -	if (!bvl)
> -		goto no_bvl;
> -
> -	bio->bi_max_vecs = nr_iovecs;
> -	bio->bi_io_vec = bvl;
> -	bio->bi_destructor = pkt_bio_destructor;
> -
> -	return bio;
> -
> - no_bvl:
> -	kfree(bio);
> - no_bio:
> -	return NULL;
> -}
> -
>  /*
>   * Allocate a packet_data struct
>   */
> @@ -567,10 +537,13 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
>  		goto no_pkt;
>  
>  	pkt->frames = frames;
> -	pkt->w_bio = pkt_bio_alloc(frames);
> +	pkt->w_bio = bio_kmalloc(GFP_KERNEL, frames);
>  	if (!pkt->w_bio)
>  		goto no_bio;
>  
> +	pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
> +	pkt->w_bio->bi_private = pkt;
> +
>  	for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {
>  		pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
>  		if (!pkt->pages[i])
> @@ -581,9 +554,12 @@ static struct packet_data *pkt_alloc_packet_data(int frames)
>  	bio_list_init(&pkt->orig_bios);
>  
>  	for (i = 0; i < frames; i++) {
> -		struct bio *bio = pkt_bio_alloc(1);
> +		struct bio *bio = bio_kmalloc(GFP_KERNEL, 1);
>  		if (!bio)
>  			goto no_rd_bio;
> +
> +		bio->bi_end_io = pkt_end_io_read;
> +		bio->bi_private = pkt;
>  		pkt->r_bios[i] = bio;
>  	}
>  
> @@ -1111,21 +1087,15 @@ static void pkt_gather_data(struct pktcdvd_device *pd, struct packet_data *pkt)
>  	 * Schedule reads for missing parts of the packet.
>  	 */
>  	for (f = 0; f < pkt->frames; f++) {
> -		struct bio_vec *vec;
> -
>  		int p, offset;
> +
>  		if (written[f])
>  			continue;
> +
>  		bio = pkt->r_bios[f];
> -		vec = bio->bi_io_vec;
> -		bio_init(bio);
> -		bio->bi_max_vecs = 1;
> -		bio->bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);
> -		bio->bi_bdev = pd->bdev;
> -		bio->bi_end_io = pkt_end_io_read;
> -		bio->bi_private = pkt;
> -		bio->bi_io_vec = vec;
> -		bio->bi_destructor = pkt_bio_destructor;
> +		bio_reset(bio);
> +		bio->bi_sector	= pkt->sector + f * (CD_FRAMESIZE >> 9);
> +		bio->bi_bdev	= pd->bdev;
>  
>  		p = (f * CD_FRAMESIZE) / PAGE_SIZE;
>  		offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
> @@ -1418,14 +1388,9 @@ static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt)
>  	}
>  
>  	/* Start the write request */
> -	bio_init(pkt->w_bio);
> -	pkt->w_bio->bi_max_vecs = PACKET_MAX_SIZE;
> +	bio_reset(pkt->w_bio);
>  	pkt->w_bio->bi_sector = pkt->sector;
>  	pkt->w_bio->bi_bdev = pd->bdev;
> -	pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
> -	pkt->w_bio->bi_private = pkt;
> -	pkt->w_bio->bi_io_vec = bvec;
> -	pkt->w_bio->bi_destructor = pkt_bio_destructor;
>  	for (f = 0; f < pkt->frames; f++)
>  		if (!bio_add_page(pkt->w_bio, bvec[f].bv_page, CD_FRAMESIZE, bvec[f].bv_offset))
>  			BUG();
> -- 
> 1.7.7.3
> 

-- 
tejun


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