* [PATCH V2] block: don't use for-inside-for in bio_for_each_segment_all
@ 2019-04-07 8:53 Ming Lei
2019-04-08 6:16 ` Christoph Hellwig
0 siblings, 1 reply; 5+ messages in thread
From: Ming Lei @ 2019-04-07 8:53 UTC (permalink / raw)
To: Jens Axboe
Cc: linux-block, Ming Lei, Qu Wenruo, linux-btrfs, linux-fsdevel,
Omar Sandoval, Christoph Hellwig
Commit 6dc4f100c175 ("block: allow bio_for_each_segment_all() to
iterate over multi-page bvec") changes bio_for_each_segment_all()
to use for-inside-for.
This way breaks all bio_for_each_segment_all() call with error out
branch via 'break', since now 'break' can only break from the inner
loop.
Fixes this issue by implementing bio_for_each_segment_all() via
single 'for' loop, and now the logic is very similar with normal
bvec iterator.
Cc: Qu Wenruo <quwenruo.btrfs@gmx.com>
Cc: linux-btrfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Reported-and-Tested-by: Qu Wenruo <quwenruo.btrfs@gmx.com>
Fixes: 6dc4f100c175 ("block: allow bio_for_each_segment_all() to iterate over multi-page bvec")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
include/linux/bio.h | 20 ++++++++++++--------
include/linux/bvec.h | 23 +++++++++++++++--------
2 files changed, 27 insertions(+), 16 deletions(-)
diff --git a/include/linux/bio.h b/include/linux/bio.h
index bb6090aa165d..9c583bf98ff9 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -120,19 +120,23 @@ static inline bool bio_full(struct bio *bio)
return bio->bi_vcnt >= bio->bi_max_vecs;
}
-#define mp_bvec_for_each_segment(bv, bvl, i, iter_all) \
- for (bv = bvec_init_iter_all(&iter_all); \
- (iter_all.done < (bvl)->bv_len) && \
- (mp_bvec_next_segment((bvl), &iter_all), 1); \
- iter_all.done += bv->bv_len, i += 1)
+static inline bool bio_next_segment(const struct bio *bio,
+ struct bvec_iter_all *iter)
+{
+ if (iter->idx >= bio->bi_vcnt)
+ return false;
+
+ bvec_advance(&bio->bi_io_vec[iter->idx], iter);
+ return true;
+}
/*
* drivers should _never_ use the all version - the bio may have been split
* before it got to the driver and the driver won't own all of it
*/
-#define bio_for_each_segment_all(bvl, bio, i, iter_all) \
- for (i = 0, iter_all.idx = 0; iter_all.idx < (bio)->bi_vcnt; iter_all.idx++) \
- mp_bvec_for_each_segment(bvl, &((bio)->bi_io_vec[iter_all.idx]), i, iter_all)
+#define bio_for_each_segment_all(bvl, bio, i, iter) \
+ for (i = 0, bvl = bvec_init_iter_all(&iter); \
+ bio_next_segment((bio), &iter); i++)
static inline void bio_advance_iter(struct bio *bio, struct bvec_iter *iter,
unsigned bytes)
diff --git a/include/linux/bvec.h b/include/linux/bvec.h
index f6275c4da13a..67eda310b643 100644
--- a/include/linux/bvec.h
+++ b/include/linux/bvec.h
@@ -47,8 +47,9 @@ struct bvec_iter {
struct bvec_iter_all {
struct bio_vec bv;
- int idx;
- unsigned done;
+ int idx; /* current index into bvec table */
+ unsigned bvec_done; /* number of bytes completed in
+ currnet bvec */
};
static inline struct page *bvec_nth_page(struct page *page, int idx)
@@ -145,18 +146,18 @@ static inline bool bvec_iter_advance(const struct bio_vec *bv,
static inline struct bio_vec *bvec_init_iter_all(struct bvec_iter_all *iter_all)
{
- iter_all->bv.bv_page = NULL;
- iter_all->done = 0;
+ iter_all->bvec_done = 0;
+ iter_all->idx = 0;
return &iter_all->bv;
}
-static inline void mp_bvec_next_segment(const struct bio_vec *bvec,
- struct bvec_iter_all *iter_all)
+static inline void bvec_advance(const struct bio_vec *bvec,
+ struct bvec_iter_all *iter_all)
{
struct bio_vec *bv = &iter_all->bv;
- if (bv->bv_page) {
+ if (iter_all->bvec_done) {
bv->bv_page = nth_page(bv->bv_page, 1);
bv->bv_offset = 0;
} else {
@@ -164,7 +165,13 @@ static inline void mp_bvec_next_segment(const struct bio_vec *bvec,
bv->bv_offset = bvec->bv_offset;
}
bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,
- bvec->bv_len - iter_all->done);
+ bvec->bv_len - iter_all->bvec_done);
+ iter_all->bvec_done += bv->bv_len;
+
+ if (iter_all->bvec_done == bvec->bv_len) {
+ iter_all->idx++;
+ iter_all->bvec_done = 0;
+ }
}
/*
--
2.9.5
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH V2] block: don't use for-inside-for in bio_for_each_segment_all
2019-04-07 8:53 [PATCH V2] block: don't use for-inside-for in bio_for_each_segment_all Ming Lei
@ 2019-04-08 6:16 ` Christoph Hellwig
2019-04-08 8:33 ` Christoph Hellwig
0 siblings, 1 reply; 5+ messages in thread
From: Christoph Hellwig @ 2019-04-08 6:16 UTC (permalink / raw)
To: Ming Lei
Cc: Jens Axboe, linux-block, Qu Wenruo, linux-btrfs, linux-fsdevel,
Omar Sandoval, Christoph Hellwig
Looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH V2] block: don't use for-inside-for in bio_for_each_segment_all
2019-04-08 6:16 ` Christoph Hellwig
@ 2019-04-08 8:33 ` Christoph Hellwig
2019-04-08 8:46 ` Ming Lei
0 siblings, 1 reply; 5+ messages in thread
From: Christoph Hellwig @ 2019-04-08 8:33 UTC (permalink / raw)
To: Ming Lei
Cc: Jens Axboe, linux-block, Qu Wenruo, linux-btrfs, linux-fsdevel,
Omar Sandoval, Christoph Hellwig
On Mon, Apr 08, 2019 at 08:16:04AM +0200, Christoph Hellwig wrote:
> Looks good:
>
> Reviewed-by: Christoph Hellwig <hch@lst.de>
Actually.. I just noticed the gratious done rename creates a (trivial)
conflict in a series I was about to submit for 5.2. Can you respin
it without the rename to make everyones life a littler easier?
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH V2] block: don't use for-inside-for in bio_for_each_segment_all
2019-04-08 8:33 ` Christoph Hellwig
@ 2019-04-08 8:46 ` Ming Lei
2019-04-08 10:47 ` Christoph Hellwig
0 siblings, 1 reply; 5+ messages in thread
From: Ming Lei @ 2019-04-08 8:46 UTC (permalink / raw)
To: Christoph Hellwig
Cc: Ming Lei, Jens Axboe, linux-block, Qu Wenruo, Btrfs BTRFS,
Linux FS Devel, Omar Sandoval
On Mon, Apr 8, 2019 at 4:34 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Mon, Apr 08, 2019 at 08:16:04AM +0200, Christoph Hellwig wrote:
> > Looks good:
> >
> > Reviewed-by: Christoph Hellwig <hch@lst.de>
>
> Actually.. I just noticed the gratious done rename creates a (trivial)
> conflict in a series I was about to submit for 5.2. Can you respin
> it without the rename to make everyones life a littler easier?
Yeah, no problem.
You mean the 'done->bvec_done' rename?
Thanks,
Ming Lei
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH V2] block: don't use for-inside-for in bio_for_each_segment_all
2019-04-08 8:46 ` Ming Lei
@ 2019-04-08 10:47 ` Christoph Hellwig
0 siblings, 0 replies; 5+ messages in thread
From: Christoph Hellwig @ 2019-04-08 10:47 UTC (permalink / raw)
To: Ming Lei
Cc: Christoph Hellwig, Ming Lei, Jens Axboe, linux-block, Qu Wenruo,
Btrfs BTRFS, Linux FS Devel, Omar Sandoval
On Mon, Apr 08, 2019 at 04:46:33PM +0800, Ming Lei wrote:
> > Actually.. I just noticed the gratious done rename creates a (trivial)
> > conflict in a series I was about to submit for 5.2. Can you respin
> > it without the rename to make everyones life a littler easier?
>
> Yeah, no problem.
>
> You mean the 'done->bvec_done' rename?
Yes.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-04-08 10:47 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-04-07 8:53 [PATCH V2] block: don't use for-inside-for in bio_for_each_segment_all Ming Lei
2019-04-08 6:16 ` Christoph Hellwig
2019-04-08 8:33 ` Christoph Hellwig
2019-04-08 8:46 ` Ming Lei
2019-04-08 10:47 ` Christoph Hellwig
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).