[PATCH v3 41/49] xfs: convert to bio_for_each_segment_all_sp()

[PATCH v3 41/49] xfs: convert to bio_for_each_segment_all_sp()

[Ming Lei]

Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 fs/xfs/xfs_aops.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 6bf120bb1a17..94df43dcae0b 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -139,6 +139,7 @@ xfs_destroy_ioend(
 	for (bio = &ioend->io_inline_bio; bio; bio = next) {
 		struct bio_vec	*bvec;
 		int		i;
+		struct bvec_iter_all bia;
 
 		/*
 		 * For the last bio, bi_private points to the ioend, so we
@@ -150,7 +151,7 @@ xfs_destroy_ioend(
 			next = bio->bi_private;
 
 		/* walk each page on bio, ending page IO on them */
-		bio_for_each_segment_all(bvec, bio, i)
+		bio_for_each_segment_all_sp(bvec, bio, i, bia)
 			xfs_finish_page_writeback(inode, bvec, error);
 
 		bio_put(bio);
-- 
2.9.4

Re: [PATCH v3 41/49] xfs: convert to bio_for_each_segment_all_sp()

[Darrick J. Wong]

On Tue, Aug 08, 2017 at 04:45:40PM +0800, Ming Lei wrote:

Sure would be nice to have a changelog explaining why we're doing this.

> Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
> Cc: linux-xfs@vger.kernel.org
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>  fs/xfs/xfs_aops.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> index 6bf120bb1a17..94df43dcae0b 100644
> --- a/fs/xfs/xfs_aops.c
> +++ b/fs/xfs/xfs_aops.c
> @@ -139,6 +139,7 @@ xfs_destroy_ioend(
>  	for (bio = &ioend->io_inline_bio; bio; bio = next) {
>  		struct bio_vec	*bvec;
>  		int		i;
> +		struct bvec_iter_all bia;
>  
>  		/*
>  		 * For the last bio, bi_private points to the ioend, so we
> @@ -150,7 +151,7 @@ xfs_destroy_ioend(
>  			next = bio->bi_private;
>  
>  		/* walk each page on bio, ending page IO on them */
> -		bio_for_each_segment_all(bvec, bio, i)
> +		bio_for_each_segment_all_sp(bvec, bio, i, bia)

It's confusing that you're splitting the old bio_for_each_segment_all
into multipage and singlepage variants, but bio_for_each_segment_all
continues to exist?

Hmm, the new multipage variant aliases the name bio_for_each_segment_all,
so clearly the _all function's sematics have changed a bit, but its name
and signature haven't, which seems likely to trip up someone who didn't
notice the behavioral change.

Is it still valid to call bio_for_each_segment_all?  I get the feeling
from this patchset that you're really supposed to decide whether you
want one page at a time or more than one page at a time and choose _sp
or _mp?

(And, seeing how this was the only patch sent to this list, the chances
are higher of someone missing out on these subtle changes...)

--D

>  			xfs_finish_page_writeback(inode, bvec, error);
>  
>  		bio_put(bio);
> -- 
> 2.9.4
> 
> --
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Re: [PATCH v3 41/49] xfs: convert to bio_for_each_segment_all_sp()

[Ming Lei]

On Tue, Aug 08, 2017 at 09:32:32AM -0700, Darrick J. Wong wrote:
> On Tue, Aug 08, 2017 at 04:45:40PM +0800, Ming Lei wrote:
> 
> Sure would be nice to have a changelog explaining why we're doing this.
> 
> > Cc: "Darrick J. Wong" <darrick.wong@oracle.com>
> > Cc: linux-xfs@vger.kernel.org
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> >  fs/xfs/xfs_aops.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> > index 6bf120bb1a17..94df43dcae0b 100644
> > --- a/fs/xfs/xfs_aops.c
> > +++ b/fs/xfs/xfs_aops.c
> > @@ -139,6 +139,7 @@ xfs_destroy_ioend(
> >  	for (bio = &ioend->io_inline_bio; bio; bio = next) {
> >  		struct bio_vec	*bvec;
> >  		int		i;
> > +		struct bvec_iter_all bia;
> >  
> >  		/*
> >  		 * For the last bio, bi_private points to the ioend, so we
> > @@ -150,7 +151,7 @@ xfs_destroy_ioend(
> >  			next = bio->bi_private;
> >  
> >  		/* walk each page on bio, ending page IO on them */
> > -		bio_for_each_segment_all(bvec, bio, i)
> > +		bio_for_each_segment_all_sp(bvec, bio, i, bia)
> 
> It's confusing that you're splitting the old bio_for_each_segment_all
> into multipage and singlepage variants, but bio_for_each_segment_all
> continues to exist?

No, it shouldn't, will remove it in V4.

> 
> Hmm, the new multipage variant aliases the name bio_for_each_segment_all,
> so clearly the _all function's sematics have changed a bit, but its name
> and signature haven't, which seems likely to trip up someone who didn't
> notice the behavioral change.

bio_for_each_segment_all_mp() is introduced for providing previous
sematics of bio_for_each_segment_all(), and there is few cases in
which bvec table need to be updated.

> 
> Is it still valid to call bio_for_each_segment_all?  I get the feeling

No, bio_for_each_segment_all_mp() should be used instead. But my plan is
to rename bio_for_each_segment_all_mp() into bio_for_each_segment_all()
and bio_for_each_segment_all_sp() into bio_for_each_page() once this
patchset is merged.

> from this patchset that you're really supposed to decide whether you
> want one page at a time or more than one page at a time and choose _sp
> or _mp?

Yeah.

> 
> (And, seeing how this was the only patch sent to this list, the chances
> are higher of someone missing out on these subtle changes...)

OK, will CC you the cover letter next time.

-- 
Ming