[2/2] block: delete bio_uninit

Commit Message

Shaohua Li July 12, 2017, 6 p.m. UTC

From: Shaohua Li <[e-mail]>

bio_uninit only calls bio_disassociate_task now. It's meaningless to
have a wrap.

Cc: Christoph Hellwig <[e-mail]>
Signed-off-by: Shaohua Li <[e-mail]>
---
 block/bio.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

Comments

Christoph Hellwig July 13, 2017, 7:45 a.m. UTC | #1

>  static void bio_free(struct bio *bio)
>  {
>  	struct bio_set *bs = bio->bi_pool;
>  	void *p;
>  
> -	bio_uninit(bio);
> +	bio_disassociate_task(bio);

As said in the last mail I think there is no point in having this call..

> @@ -294,7 +289,7 @@ void bio_reset(struct bio *bio)
>  {
>  	unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
>  
> -	bio_uninit(bio);
> +	bio_disassociate_task(bio);

.. and this one.  And I suspect it would make sense to have all these
changes in a single patch.

Shaohua Li July 13, 2017, 4:50 p.m. UTC | #2

On Thu, Jul 13, 2017 at 09:45:19AM +0200, Christoph Hellwig wrote:
> >  static void bio_free(struct bio *bio)
> >  {
> >  	struct bio_set *bs = bio->bi_pool;
> >  	void *p;
> >  
> > -	bio_uninit(bio);
> > +	bio_disassociate_task(bio);
> 
> As said in the last mail I think there is no point in having this call..

I'm hesitant to do this. bio_associate_blkcg/bio_associate_current can be
called in any time for a bio, so we not just attach cgroup info to info in bio
submit (maybe the bio_associate_blkcg/bio_associate_current callers do sumbit
always, but I didn't audit yet). The other reason is I'd like
blk_throtl_bio_endio is only called once for the whole bio not for splitted
bio, so this depends on bio_free to free cgroup info for chained bio which
always does bio_put.

> > @@ -294,7 +289,7 @@ void bio_reset(struct bio *bio)
> >  {
> >  	unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
> >  
> > -	bio_uninit(bio);
> > +	bio_disassociate_task(bio);
> 
> .. and this one.  And I suspect it would make sense to have all these
> changes in a single patch.

This one is likely ok, but again I didn't audit yet. I'm ok these changes are
in a single patch.

Thanks,
Shaohua

Christoph Hellwig July 13, 2017, 5:23 p.m. UTC | #3

On Thu, Jul 13, 2017 at 09:50:23AM -0700, Shaohua Li wrote:
> > As said in the last mail I think there is no point in having this call..
> 
> I'm hesitant to do this. bio_associate_blkcg/bio_associate_current can be
> called in any time for a bio, so we not just attach cgroup info to info in bio
> submit (maybe the bio_associate_blkcg/bio_associate_current callers do sumbit
> always, but I didn't audit yet).

bio_associate_current is only called from blk_throtl_assoc_bio, which
is only called from blk_throtl_bio, which is only called from
blkcg_bio_issue_check, which is only called from
generic_make_request_checks, which is only called from
generic_make_request, which at that point consumes the bio from the
callers perspective.

bio_associate_blkcg might be a different story, but then we should
treat both very differently.

> The other reason is I'd like
> blk_throtl_bio_endio is only called once for the whole bio not for splitted
> bio, so this depends on bio_free to free cgroup info for chained bio which
> always does bio_put.

Then we'll need to fix that.  We really should not require every
caller of bio_init to pair it with a new uninit call, which would be
a whole lot more work.

Patch

diff --git a/block/bio.c b/block/bio.c
index ce078fb..8773d1b 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -240,17 +240,12 @@  struct bio_vec *bvec_alloc(gfp_t gfp_mask, int nr, unsigned long *idx,
 	return bvl;
 }
 
-static void bio_uninit(struct bio *bio)
-{
-	bio_disassociate_task(bio);
-}
-
 static void bio_free(struct bio *bio)
 {
 	struct bio_set *bs = bio->bi_pool;
 	void *p;
 
-	bio_uninit(bio);
+	bio_disassociate_task(bio);
 
 	if (bs) {
 		bvec_free(bs->bvec_pool, bio->bi_io_vec, BVEC_POOL_IDX(bio));
@@ -294,7 +289,7 @@  void bio_reset(struct bio *bio)
 {
 	unsigned long flags = bio->bi_flags & (~0UL << BIO_RESET_BITS);
 
-	bio_uninit(bio);
+	bio_disassociate_task(bio);
 
 	memset(bio, 0, BIO_RESET_BYTES);
 	bio->bi_flags = flags;
@@ -1828,7 +1823,7 @@  void bio_endio(struct bio *bio)
 
 	blk_throtl_bio_endio(bio);
 	/* release cgroup info */
-	bio_uninit(bio);
+	bio_disassociate_task(bio);
 	if (bio->bi_end_io)
 		bio->bi_end_io(bio);
 }