On Wed, Apr 3, 2019 at 5:16 PM Johannes Thumshirn <jthumshirn@xxxxxxx> wrote:
>
> With the introduction of BIO_NO_PAGE_REF we've used up all available bits
> in bio::bi_flags.
>
> Convert the defines of the flags to an enum and add a BUILD_BUG_ON() call
> to make sure no-one adds a new one and thus overrides the BVEC_POOL_IDX
> causing crashes.
>
> Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
>
> ---
> This used to be part of my bio patchset but as it's a) not clear why we
> end up calling bio_put() on the on-stack bio and b) the needed prep patch
> for the fix introduces a regression, I've decided to sent this patch out
> as it's valid on it's own.
>
> I dropped Hannes' and Christoph's R-b though, as the context changed.
> ---
> block/bio.c | 3 +++
> include/linux/blk_types.h | 29 ++++++++++++++++-------------
> 2 files changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/block/bio.c b/block/bio.c
> index 8d516d508ae3..c2592c5d70b9 100644
> --- a/block/bio.c
> +++ b/block/bio.c
> @@ -2218,6 +2218,9 @@ static int __init init_bio(void)
> bio_slab_nr = 0;
> bio_slabs = kcalloc(bio_slab_max, sizeof(struct bio_slab),
> GFP_KERNEL);
> +
> + BUILD_BUG_ON(BIO_FLAG_LAST > BVEC_POOL_OFFSET);
> +
> if (!bio_slabs)
> panic("bio: can't allocate bios\n");
>
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 791fee35df88..be418275763c 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -215,21 +215,24 @@ struct bio {
> /*
> * bio flags
> */
> -#define BIO_NO_PAGE_REF 0 /* don't put release vec pages */
> -#define BIO_SEG_VALID 1 /* bi_phys_segments valid */
> -#define BIO_CLONED 2 /* doesn't own data */
> -#define BIO_BOUNCED 3 /* bio is a bounce bio */
> -#define BIO_USER_MAPPED 4 /* contains user pages */
> -#define BIO_NULL_MAPPED 5 /* contains invalid user pages */
> -#define BIO_QUIET 6 /* Make BIO Quiet */
> -#define BIO_CHAIN 7 /* chained bio, ->bi_remaining in effect */
> -#define BIO_REFFED 8 /* bio has elevated ->bi_cnt */
> -#define BIO_THROTTLED 9 /* This bio has already been subjected to
> +enum {
> + BIO_NO_PAGE_REF, /* don't put release vec pages */
> + BIO_SEG_VALID, /* bi_phys_segments valid */
> + BIO_CLONED, /* doesn't own data */
> + BIO_BOUNCED, /* bio is a bounce bio */
> + BIO_USER_MAPPED, /* contains user pages */
> + BIO_NULL_MAPPED, /* contains invalid user pages */
> + BIO_QUIET, /* Make BIO Quiet */
> + BIO_CHAIN, /* chained bio, ->bi_remaining in effect */
> + BIO_REFFED, /* bio has elevated ->bi_cnt */
> + BIO_THROTTLED, /* This bio has already been subjected to
> * throttling rules. Don't do it again. */
> -#define BIO_TRACE_COMPLETION 10 /* bio_endio() should trace the final completion
> + BIO_TRACE_COMPLETION, /* bio_endio() should trace the final completion
> * of this bio. */
> -#define BIO_QUEUE_ENTERED 11 /* can use blk_queue_enter_live() */
> -#define BIO_TRACKED 12 /* set if bio goes through the rq_qos path */
> + BIO_QUEUE_ENTERED, /* can use blk_queue_enter_live() */
> + BIO_TRACKED, /* set if bio goes through the rq_qos path */
> + BIO_FLAG_LAST
> +};
>
> /* See BVEC_POOL_OFFSET below before adding new flags */
Looks fine,
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
Thanks,
Ming Lei
