btrfs: add helper to initialize the non-bio part of btrfs_io_bio
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.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index 5037fd9..cbd0a9a 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -2654,22 +2654,28 @@
}
/*
+ * 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 @@
/* 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 @@
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;