Commit 1200e07f authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

block: don't use for-inside-for in bio_for_each_segment_all 



Commit 6dc4f100 ("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>
Reviewed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Reported-and-Tested-by: default avatarQu Wenruo <quwenruo.btrfs@gmx.com>
Fixes: 6dc4f100 ("block: allow bio_for_each_segment_all() to iterate over multi-page bvec")
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent 15ade5d2

include/linux/bio.h

+12 −8
Original line number Diff line number Diff line
@@ -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)

include/linux/bvec.h

+10 −4
Original line number Diff line number Diff line
@@ -145,18 +145,18 @@ 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->idx = 0;



	return &iter_all->bv;

}



static inline void mp_bvec_next_segment(const struct bio_vec *bvec,

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->done) {

		bv->bv_page = nth_page(bv->bv_page, 1);

		bv->bv_offset = 0;

	} else {
@@ -165,6 +165,12 @@ static inline void mp_bvec_next_segment(const struct bio_vec *bvec, 
	}

	bv->bv_len = min_t(unsigned int, PAGE_SIZE - bv->bv_offset,

			   bvec->bv_len - iter_all->done);

	iter_all->done += bv->bv_len;



	if (iter_all->done == bvec->bv_len) {

		iter_all->idx++;

		iter_all->done = 0;

	}

}



/*

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