Thread (1 message) 1 message, 1 author, 2012-05-18

Re: [PATCH 09/13] block: Add an explicit bio flag for bios that own their bvec

From: Boaz Harrosh <hidden>
Date: 2012-05-18 17:07:40
Also in: dm-devel, linux-fsdevel, lkml

On 05/18/2012 05:59 AM, koverstreet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org wrote:
quoted hunk
From: Kent Overstreet <redacted>

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 <redacted>
---
 fs/bio.c                  |    3 ++-
 include/linux/blk_types.h |    1 +
 2 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/fs/bio.c b/fs/bio.c
index ecc9088..3332800 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -234,7 +234,7 @@ void bio_free(struct bio *bio, struct bio_set *bs)
 {
 	void *p;
 
-	if (bio_has_allocated_vec(bio))
+	if (bio_flagged(bio, BIO_HAS_VEC))
 		bvec_free_bs(bs, bio->bi_io_vec, BIO_POOL_IDX(bio));
 
 	if (bio_integrity(bio))
@@ -305,6 +305,7 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, int nr_iovecs, struct bio_set *bs)
 			goto err_free;
 
 		nr_iovecs = bvec_nr_vecs(idx);
+		bio->bi_flags |= 1 << BIO_HAS_VEC;
 	}
 out_set:
 	bio->bi_flags |= idx << BIO_POOL_OFFSET;
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index bd9a610..10fca21 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -101,6 +101,7 @@ struct bio {
 #define BIO_FS_INTEGRITY 9	/* fs owns integrity data, not block layer */
 #define BIO_QUIET	10	/* Make BIO Quiet */
 #define BIO_MAPPED_INTEGRITY 11/* integrity metadata has been remapped */
+#define BIO_HAS_VEC	12	/* bio_free() should free bvec */

Just an English nit
BIO with out any VECs is when bi_max_vecs is zero. Id prefer a name that
denotes allocation or ownership.
BIO_OWN_VEC or BIO_ALLOC_VEC or BIO_DELETE_VEC

And one technical problem.

I would prefer to negate this bit. Zero is the default, set on
the exception. Safer and also more logical.

 BIO_NO_DELETE_VEC
 #define bio_flagged(bio, flag)	((bio)->bi_flags & (1 << (flag)))
 
 /*


Thanks
Boaz
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