Re: [PATCH 03/14] xfs: dynamically allocate btree scrub context structure

Chandan Babu R
2021-09-20T10:09:43Z

On 18 Sep 2021 at 06:59, Darrick J. Wong wrote:
> From: Darrick J. Wong <djwong@kernel.org>
>
> Reorganize struct xchk_btree so that we can dynamically size the context
> structure to fit the type of btree cursor that we have. This will
> enable us to use memory more efficiently once we start adding very tall
> btree types.

The changes look good to me from the perspective of functional correctness.

Reviewed-by: Chandan Babu R <chandan.babu@oracle.com>

>
> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> ---
> fs/xfs/scrub/btree.c | 38 +++++++++++++++++---------------------
> fs/xfs/scrub/btree.h | 16 +++++++++++++---
> 2 files changed, 30 insertions(+), 24 deletions(-)
>
>
> diff --git a/fs/xfs/scrub/btree.c b/fs/xfs/scrub/btree.c
> index 26dcb4691e31..7b7762ae22e5 100644
> --- a/fs/xfs/scrub/btree.c
> +++ b/fs/xfs/scrub/btree.c
> @@ -141,9 +141,10 @@ xchk_btree_rec(
> trace_xchk_btree_rec(bs->sc, cur, 0);
>
> /* If this isn't the first record, are they in order? */
> - if (!bs->firstrec && !cur->bc_ops->recs_inorder(cur, &bs->lastrec, rec))
> + if (bs->levels[0].has_lastkey &&
> + !cur->bc_ops->recs_inorder(cur, &bs->lastrec, rec))
> xchk_btree_set_corrupt(bs->sc, cur, 0);
> - bs->firstrec = false;
> + bs->levels[0].has_lastkey = true;
> memcpy(&bs->lastrec, rec, cur->bc_ops->rec_len);
>
> if (cur->bc_nlevels == 1)
> @@ -188,11 +189,11 @@ xchk_btree_key(
> trace_xchk_btree_key(bs->sc, cur, level);
>
> /* If this isn't the first key, are they in order? */
> - if (!bs->firstkey[level] &&
> - !cur->bc_ops->keys_inorder(cur, &bs->lastkey[level], key))
> + if (bs->levels[level].has_lastkey &&
> + !cur->bc_ops->keys_inorder(cur, &bs->levels[level].lastkey, key))
> xchk_btree_set_corrupt(bs->sc, cur, level);
> - bs->firstkey[level] = false;
> - memcpy(&bs->lastkey[level], key, cur->bc_ops->key_len);
> + bs->levels[level].has_lastkey = true;
> + memcpy(&bs->levels[level].lastkey, key, cur->bc_ops->key_len);
>
> if (level + 1 >= cur->bc_nlevels)
> return;
> @@ -632,38 +633,33 @@ xchk_btree(
> union xfs_btree_ptr *pp;
> union xfs_btree_rec *recp;
> struct xfs_btree_block *block;
> - int level;
> struct xfs_buf *bp;
> struct check_owner *co;
> struct check_owner *n;
> - int i;
> + size_t cur_sz;
> + int level;
> int error = 0;
>
> /*
> * Allocate the btree scrub context from the heap, because this
> - * structure can get rather large.
> + * structure can get rather large. Don't let a caller feed us a
> + * totally absurd size.
> */
> - bs = kmem_zalloc(sizeof(struct xchk_btree), KM_NOFS | KM_MAYFAIL);
> + cur_sz = xchk_btree_sizeof(cur->bc_nlevels);
> + if (cur_sz > PAGE_SIZE) {
> + xchk_btree_set_corrupt(sc, cur, 0);
> + return 0;
> + }
> + bs = kmem_zalloc(cur_sz, KM_NOFS | KM_MAYFAIL);
> if (!bs)
> return -ENOMEM;
> bs->cur = cur;
> bs->scrub_rec = scrub_fn;
> bs->oinfo = oinfo;
> - bs->firstrec = true;
> bs->private = private;
> bs->sc = sc;
> -
> - /* Initialize scrub state */
> - for (i = 0; i < XFS_BTREE_MAXLEVELS; i++)
> - bs->firstkey[i] = true;
> INIT_LIST_HEAD(&bs->to_check);
>
> - /* Don't try to check a tree with a height we can't handle. */
> - if (cur->bc_nlevels > XFS_BTREE_MAXLEVELS) {
> - xchk_btree_set_corrupt(sc, cur, 0);
> - goto out;
> - }
> -
> /*
> * Load the root of the btree. The helper function absorbs
> * error codes for us.
> diff --git a/fs/xfs/scrub/btree.h b/fs/xfs/scrub/btree.h
> index d5c0b0cbc505..7f8c54d8020e 100644
> --- a/fs/xfs/scrub/btree.h
> +++ b/fs/xfs/scrub/btree.h
> @@ -29,6 +29,11 @@ typedef int (*xchk_btree_rec_fn)(
> struct xchk_btree *bs,
> const union xfs_btree_rec *rec);
>
> +struct xchk_btree_levels {
> + union xfs_btree_key lastkey;
> + bool has_lastkey;
> +};
> +
> struct xchk_btree {
> /* caller-provided scrub state */
> struct xfs_scrub *sc;
> @@ -39,12 +44,17 @@ struct xchk_btree {
>
> /* internal scrub state */
> union xfs_btree_rec lastrec;
> - bool firstrec;
> - union xfs_btree_key lastkey[XFS_BTREE_MAXLEVELS];
> - bool firstkey[XFS_BTREE_MAXLEVELS];
> struct list_head to_check;
> + struct xchk_btree_levels levels[];
> };
>
> +static inline size_t
> +xchk_btree_sizeof(unsigned int levels)
> +{
> + return sizeof(struct xchk_btree) +
> + (levels * sizeof(struct xchk_btree_levels));
> +}
> +
> int xchk_btree(struct xfs_scrub *sc, struct xfs_btree_cur *cur,
> xchk_btree_rec_fn scrub_fn, const struct xfs_owner_info *oinfo,
> void *private);

--
chandan