On Mon, Jun 12, 2017 at 05:29:39PM +0200, David Sterba wrote:
> We use btrfs_bioset for bios and ask to allocate the entire size of
> btrfs_io_bio from btrfs bio_alloc_bioset. The member 'bio' is
> initialized but the bytes from 0 to offset of 'bio' are left
> uninitialized. Although we initialize some of the members in our
> helpers, we should initialize the whole structures.
>
Reviewed-by: Liu Bo <bo.li....@oracle.com>
-liubo
> Signed-off-by: David Sterba <dste...@suse.com>
> ---
> fs/btrfs/extent_io.c | 30 ++++++++++++++----------------
> 1 file changed, 14 insertions(+), 16 deletions(-)
>
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 5037fd918f43..cbd0a9a1daa5 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -2654,22 +2654,28 @@ static void end_bio_extent_readpage(struct bio *bio)
> }
>
> /*
> + * Initialize the members up to but not including 'bio'. Use after
> allocating a
> + * new bio by bio_alloc_bioset as it does not initialize the bytes outside of
> + * 'bio' because use of __GFP_ZERO is not supported.
> + */
> +static inline void btrfs_io_bio_init(struct btrfs_io_bio *btrfs_bio)
> +{
> + memset(btrfs_bio, 0, offsetof(struct btrfs_io_bio, bio));
> +}
> +
> +/*
> * The following helpers allocate a bio. As it's backed by a bioset, it'll
> * never fail. We're returning a bio right now but you can call btrfs_io_bio
> * for the appropriate container_of magic
> */
> struct bio *btrfs_bio_alloc(struct block_device *bdev, u64 first_byte)
> {
> - struct btrfs_io_bio *btrfs_bio;
> struct bio *bio;
>
> bio = bio_alloc_bioset(GFP_NOFS, BIO_MAX_PAGES, btrfs_bioset);
> bio->bi_bdev = bdev;
> bio->bi_iter.bi_sector = first_byte >> 9;
> - btrfs_bio = btrfs_io_bio(bio);
> - btrfs_bio->csum = NULL;
> - btrfs_bio->csum_allocated = NULL;
> - btrfs_bio->end_io = NULL;
> + btrfs_io_bio_init(btrfs_io_bio(bio));
> return bio;
> }
>
> @@ -2681,24 +2687,18 @@ struct bio *btrfs_bio_clone(struct bio *bio)
> /* Bio allocation backed by a bioset does not fail */
> new = bio_clone_fast(bio, GFP_NOFS, btrfs_bioset);
> btrfs_bio = btrfs_io_bio(new);
> - btrfs_bio->csum = NULL;
> - btrfs_bio->csum_allocated = NULL;
> - btrfs_bio->end_io = NULL;
> + btrfs_io_bio_init(btrfs_bio);
> btrfs_bio->iter = bio->bi_iter;
> return new;
> }
>
> struct bio *btrfs_io_bio_alloc(gfp_t gfp_mask, unsigned int nr_iovecs)
> {
> - struct btrfs_io_bio *btrfs_bio;
> struct bio *bio;
>
> /* Bio allocation backed by a bioset does not fail */
> bio = bio_alloc_bioset(gfp_mask, nr_iovecs, btrfs_bioset);
> - btrfs_bio = btrfs_io_bio(bio);
> - btrfs_bio->csum = NULL;
> - btrfs_bio->csum_allocated = NULL;
> - btrfs_bio->end_io = NULL;
> + btrfs_io_bio_init(btrfs_io_bio(bio));
> return bio;
> }
>
> @@ -2712,9 +2712,7 @@ struct bio *btrfs_bio_clone_partial(struct bio *orig,
> int offset, int size)
> ASSERT(bio);
>
> btrfs_bio = btrfs_io_bio(bio);
> - btrfs_bio->csum = NULL;
> - btrfs_bio->csum_allocated = NULL;
> - btrfs_bio->end_io = NULL;
> + btrfs_io_bio_init(btrfs_bio);
>
> bio_trim(bio, offset >> 9, size >> 9);
> btrfs_bio->iter = bio->bi_iter;
> --
> 2.13.0
>
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