Hi Kent
When you change the semantics of an exported function, rename that
function. There may be external modules that use __bio_clone and this
change could silently introduce bugs in them.
Otherwise, the patchset looks fine.
Mikulas
On Mon, 6 Aug 2012, Kent Overstreet wrote:
> bcache creates large bios internally, and then splits them according to
> the device requirements before it sends them down. If a lower level
> device tries to clone the bio, and the original bio had more than
> BIO_MAX_PAGES, the clone will fail unecessarily.
>
> We can fix this by only cloning the bio vecs that are actually in use.
>
> Signed-off-by: Kent Overstreet <koverstreet@xxxxxxxxxx>
> ---
> drivers/block/rbd.c | 2 +-
> drivers/md/dm.c | 5 ++---
> fs/bio.c | 13 +++++++------
> 3 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index 692cf05..21edfe5 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -714,7 +714,7 @@ static struct bio *bio_chain_clone(struct bio **old, struct bio **next,
> }
>
> while (old_chain && (total < len)) {
> - tmp = bio_kmalloc(gfpmask, old_chain->bi_max_vecs);
> + tmp = bio_kmalloc(gfpmask, bio_segments(old_chain));
> if (!tmp)
> goto err_out;
>
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index 3f3c26e..193fb19 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1057,11 +1057,10 @@ static struct bio *clone_bio(struct bio *bio, sector_t sector,
> {
> struct bio *clone;
>
> - clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
> + clone = bio_alloc_bioset(GFP_NOIO, bv_count, bs);
> __bio_clone(clone, bio);
> clone->bi_sector = sector;
> - clone->bi_idx = idx;
> - clone->bi_vcnt = idx + bv_count;
> + clone->bi_vcnt = bv_count;
> clone->bi_size = to_bytes(len);
> clone->bi_flags &= ~(1 << BIO_SEG_VALID);
>
> diff --git a/fs/bio.c b/fs/bio.c
> index 38ad026..631c67e 100644
> --- a/fs/bio.c
> +++ b/fs/bio.c
> @@ -449,8 +449,9 @@ EXPORT_SYMBOL(bio_phys_segments);
> */
> void __bio_clone(struct bio *bio, struct bio *bio_src)
> {
> - memcpy(bio->bi_io_vec, bio_src->bi_io_vec,
> - bio_src->bi_max_vecs * sizeof(struct bio_vec));
> + memcpy(bio->bi_io_vec,
> + bio_iovec(bio_src),
> + bio_segments(bio_src) * sizeof(struct bio_vec));
>
> /*
> * most users will be overriding ->bi_bdev with a new target,
> @@ -459,10 +460,10 @@ void __bio_clone(struct bio *bio, struct bio *bio_src)
> bio->bi_sector = bio_src->bi_sector;
> bio->bi_bdev = bio_src->bi_bdev;
> bio->bi_flags |= 1 << BIO_CLONED;
> + bio->bi_flags &= ~(1 << BIO_SEG_VALID);
> bio->bi_rw = bio_src->bi_rw;
> - bio->bi_vcnt = bio_src->bi_vcnt;
> + bio->bi_vcnt = bio_segments(bio_src);
> bio->bi_size = bio_src->bi_size;
> - bio->bi_idx = bio_src->bi_idx;
> }
> EXPORT_SYMBOL(__bio_clone);
>
> @@ -477,7 +478,7 @@ EXPORT_SYMBOL(__bio_clone);
> struct bio *bio_clone_bioset(struct bio *bio, gfp_t gfp_mask,
> struct bio_set *bs)
> {
> - struct bio *b = bio_alloc_bioset(gfp_mask, bio->bi_max_vecs, bs);
> + struct bio *b = bio_alloc_bioset(gfp_mask, bio_segments(bio), bs);
>
> if (!b)
> return NULL;
> @@ -507,7 +508,7 @@ EXPORT_SYMBOL(bio_clone);
>
> struct bio *bio_clone_kmalloc(struct bio *bio, gfp_t gfp_mask)
> {
> - struct bio *b = bio_kmalloc(gfp_mask, bio->bi_max_vecs);
> + struct bio *b = bio_kmalloc(gfp_mask, bio_segments(bio));
>
> if (!b)
> return NULL;
> --
> 1.7.7.3
>
> --
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> https://www.redhat.com/mailman/listinfo/dm-devel
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