Re: [PATCH] lightnvm: pblk: fix bio leak on large sized io

["Matias Bjørling" <mb@lightnvm.io>]

On 1/30/19 2:53 AM, 김찬솔 wrote:
> 
> Changes:
>   1. Function pblk_rw_io to get bio* as a reference
>   2. In pblk_rw_io bio_put call on read case removed
> 
> A fix to address issue where
>   1. pblk_make_rq calls pblk_rw_io passes bio* pointer as a value (0xA)
>   2. pblk_rw_io calls blk_queue_split passing bio* pointer as reference
>   3. In blk_queue_split, when there is a split, the original bio* (0xA)
>      is passed to generic_make_requests, and the newly allocated bio is
>      returned
>   4. If NVM_IO_DONE returned, pblk_make_rq calls bio_endio on the bio*,
>      that is not the one returned by blk_queue_split
>   5. As a result bio_endio is not called on the newly allocated bio.
> 
> Signed-off-by: chansol.kim <chansol.kim@samsung.com>
> ---
>   drivers/lightnvm/pblk-init.c | 22 ++++++++--------------
>   1 file changed, 8 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/lightnvm/pblk-init.c b/drivers/lightnvm/pblk-init.c
> index b57f764d..4efc929 100644
> --- a/drivers/lightnvm/pblk-init.c
> +++ b/drivers/lightnvm/pblk-init.c
> @@ -31,30 +31,24 @@ static DECLARE_RWSEM(pblk_lock);
>   struct bio_set pblk_bio_set;
>   
>   static int pblk_rw_io(struct request_queue *q, struct pblk *pblk,
> -			  struct bio *bio)
> +			  struct bio **bio)
>   {
> -	int ret;
> -
>   	/* Read requests must be <= 256kb due to NVMe's 64 bit completion bitmap
>   	 * constraint. Writes can be of arbitrary size.
>   	 */
> -	if (bio_data_dir(bio) == READ) {
> -		blk_queue_split(q, &bio);
> -		ret = pblk_submit_read(pblk, bio);
> -		if (ret == NVM_IO_DONE && bio_flagged(bio, BIO_CLONED))
> -			bio_put(bio);

Could we kill the NVM_DONE_IO check in the pblk_rw_io, that should 
achieve the same?

> -
> -		return ret;
> +	if (bio_data_dir(*bio) == READ) {
> +		blk_queue_split(q, bio);
> +		return pblk_submit_read(pblk, *bio);
>   	}
>   
>   	/* Prevent deadlock in the case of a modest LUN configuration and large
>   	 * user I/Os. Unless stalled, the rate limiter leaves at least 256KB
>   	 * available for user I/O.
>   	 */
> -	if (pblk_get_secs(bio) > pblk_rl_max_io(&pblk->rl))
> -		blk_queue_split(q, &bio);
> +	if (pblk_get_secs(*bio) > pblk_rl_max_io(&pblk->rl))
> +		blk_queue_split(q, bio);
>   
> -	return pblk_write_to_cache(pblk, bio, PBLK_IOTYPE_USER);
> +	return pblk_write_to_cache(pblk, *bio, PBLK_IOTYPE_USER);
>   }
>   
>   static blk_qc_t pblk_make_rq(struct request_queue *q, struct bio *bio)
> @@ -69,7 +63,7 @@ static blk_qc_t pblk_make_rq(struct request_queue *q, struct bio *bio)
>   		}
>   	}
>   
> -	switch (pblk_rw_io(q, pblk, bio)) {
> +	switch (pblk_rw_io(q, pblk, &bio)) {
>   	case NVM_IO_ERR:
>   		bio_io_error(bio);
>   		break;
>