linux-kernel - [PATCH v6 08/13] block: Add an explicit bio flag for bios that own their bvec

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Message-Id: <1345655050-28199-9-git-send-email-koverstreet@google.com>
Date:	Wed, 22 Aug 2012 10:04:05 -0700
From:	Kent Overstreet <koverstreet@...gle.com>
To:	linux-bcache@...r.kernel.org, linux-kernel@...r.kernel.org,
	dm-devel@...hat.com
Cc:	Kent Overstreet <koverstreet@...gle.com>, tj@...nel.org,
	vgoyal@...hat.com, mpatocka@...hat.com, bharrosh@...asas.com,
	Jens Axboe <axboe@...nel.dk>
Subject: [PATCH v6 08/13] block: Add an explicit bio flag for bios that own their bvec

This is for the new bio splitting code. When we split a bio, if the
split occured on a bvec boundry we reuse the bvec for the new bio. But
that means bio_free() can't free it, hence the explicit flag.

Signed-off-by: Kent Overstreet <koverstreet@...gle.com>
CC: Jens Axboe <axboe@...nel.dk>
Acked-by: Tejun Heo <tj@...nel.org>
---
 fs/bio.c                  | 4 +++-
 include/linux/bio.h       | 5 -----
 include/linux/blk_types.h | 1 +
 3 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/fs/bio.c b/fs/bio.c
index a82a3c7..b9c022c 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -246,7 +246,7 @@ void bio_free(struct bio *bio)
 		return;
 	}
 
-	if (bio_has_allocated_vec(bio))
+	if (bio_flagged(bio, BIO_OWNS_VEC))
 		bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
 
 	if (bio_integrity(bio))
@@ -365,6 +365,8 @@ retry:
 		bvl = bvec_alloc_bs(gfp_mask, nr_iovecs, &idx, bs);
 		if (unlikely(!bvl))
 			goto err_free;
+
+		bio->bi_flags |= 1 << BIO_OWNS_VEC;
 	} else if (nr_iovecs) {
 		bvl = bio->bi_inline_vecs;
 	}
diff --git a/include/linux/bio.h b/include/linux/bio.h
index ba5b52e..427d05a 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -84,11 +84,6 @@ static inline void *bio_data(struct bio *bio)
 	return NULL;
 }
 
-static inline int bio_has_allocated_vec(struct bio *bio)
-{
-	return bio->bi_io_vec && bio->bi_io_vec != bio->bi_inline_vecs;
-}
-
 /*
  * will die
  */
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index 045ebe0..c1878bd 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -117,6 +117,7 @@ struct bio {
  * BIO_POOL_IDX()
  */
 #define BIO_RESET_BITS	12
+#define BIO_OWNS_VEC	12	/* bio_free() should free bvec */
 
 #define bio_flagged(bio, flag)	((bio)->bi_flags & (1 << (flag)))
 
-- 
1.7.12

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