On Wed, May 09, 2012 at 11:08:34PM -0400, Kent Overstreet wrote:
> When you allocate a bio from a bio pool, to free it you have to know
> where it came from; this adds a flag which, if set, means bi_destructor
> is the pointer to the pool and bio_put() can do the right thing.
>
> This is used in bcache, so we can cleanly use per device bio pools.
Ok, that will explain BIO_HAS_POOL flag. Why to replace
bio_has_allocated_vec() with BIO_HAS_VEC flag?
Thanks
Vivek
>
> Signed-off-by: Kent Overstreet <koverstreet@xxxxxxxxxx>
> ---
> fs/bio.c | 9 +++++++--
> include/linux/blk_types.h | 2 ++
> 2 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/fs/bio.c b/fs/bio.c
> index a965b89..6a967fc 100644
> --- a/fs/bio.c
> +++ b/fs/bio.c
> @@ -235,7 +235,7 @@ void bio_free(struct bio *bio, struct bio_set *bs)
> {
> void *p;
>
> - 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))
> @@ -301,6 +301,7 @@ 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;
> @@ -417,7 +418,11 @@ void bio_put(struct bio *bio)
> */
> if (atomic_dec_and_test(&bio->bi_cnt)) {
> bio->bi_next = NULL;
> - bio->bi_destructor(bio);
> +
> + if (bio_flagged(bio, BIO_HAS_POOL))
> + bio_free(bio, (void *) bio->bi_destructor);
> + else
> + bio->bi_destructor(bio);
> }
> }
> EXPORT_SYMBOL(bio_put);
> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> index 4053cbd..a0be8b3 100644
> --- a/include/linux/blk_types.h
> +++ b/include/linux/blk_types.h
> @@ -95,6 +95,8 @@ 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_POOL 12 /* bi_destructor points to bio_pool */
> +#define BIO_HAS_VEC 13 /* bio_free() should free bvec */
> #define bio_flagged(bio, flag) ((bio)->bi_flags & (1 << (flag)))
>
> /*
> --
> 1.7.9.rc2
>
> --
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> https://www.redhat.com/mailman/listinfo/dm-devel
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