On Thu, May 10, 2012 at 2:32 PM, Vivek Goyal <vgoyal@xxxxxxxxxx> wrote:
> 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?
Using bio_has_allocated_vec() would mean the bvec would always be
freed if it wasn't a pointer to the inline vecs - my bio splitting
code will use the bvec from the original bio for the split if it's
splitting on a bvec boundary, in which case that's not what we want.
It means "bio owns its bvec".
>
> 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
>>
>> --
>> dm-devel mailing list
>> dm-devel@xxxxxxxxxx
>> https://www.redhat.com/mailman/listinfo/dm-devel
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