On 05/24/2012 03:02 AM, Kent Overstreet wrote:
> This is for the new bio splitting code. When we split a bio, if the
> split occured on a bvec boundry we reuse the bvec for the new bio. But
> that means bio_free() can't free it, hence the explicit flag.
>
How do you insure that the original bio which owns the
bvec is not freed before the split-out bio.
Perhaps calling code needs to make sure by taking an extra
ref on the original bio, or something. If so a big fat comment
at bio_split is do.
And I understand you did not like my suggestion of negating
the meaning of the flag, so the default is zero?
Please say why?
Thanks
Boaz
> Signed-off-by: Kent Overstreet <koverstreet@xxxxxxxxxx>
> Change-Id: I040f6b501088e882a9f013d6b6e730ff04e9c1da
> ---
> fs/bio.c | 3 ++-
> include/linux/bio.h | 5 -----
> include/linux/blk_types.h | 1 +
> 3 files changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/fs/bio.c b/fs/bio.c
> index fc4a168..24b1d1c 100644
> --- a/fs/bio.c
> +++ b/fs/bio.c
> @@ -241,7 +241,7 @@ void bio_free(struct bio *bio, struct bio_set *bs)
> return;
> }
>
> - if (bio_has_allocated_vec(bio))
> + if (bio_flagged(bio, BIO_HAS_VEC))
> bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
>
> if (bio_integrity(bio))
> @@ -312,6 +312,7 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
> goto err_free;
>
> nr_iovecs = bvec_nr_vecs(idx);
> + bio->bi_flags |= 1 << BIO_HAS_VEC;
> }
> out_set:
> bio->bi_flags |= idx << BIO_POOL_OFFSET;
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 35f7c4d..8dd8cae 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -84,11 +84,6 @@ static inline void *bio_data(struct bio *bio)
> return NULL;
> }
>
> -static inline int bio_has_allocated_vec(struct bio *bio)
> -{
> - return bio->bi_io_vec && bio->bi_io_vec != bio->bi_inline_vecs;
> -}
> -
> /*
> * will die
> */
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index b6ddbf1..ab2252d 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -101,6 +101,7 @@ struct bio {
> #define BIO_FS_INTEGRITY 9 /* fs owns integrity data, not block layer */
> #define BIO_QUIET 10 /* Make BIO Quiet */
> #define BIO_MAPPED_INTEGRITY 11/* integrity metadata has been remapped */
> +#define BIO_HAS_VEC 12 /* bio_free() should free bvec */
> #define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
>
> /*
--
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